HomeMy WebLinkAbout2026-014 Design Criteria Manual UpdateDecember 19, 2025 Report No. 2026-014
INFORMAL STAFF REPORT
TO MAYOR AND CITY COUNCIL
SUBJECT:
Provide information regarding the purpose of the City’s Design Criteria Manual (DCM), the
process by which it is updated, and some notable changes proposed in the DCM update coming to
City Council for consideration on January 13, 2026.
BACKGROUND:
There are several governing documents within the City of Denton which lay out rules and criteria
on how development is to be planned, designed, and constructed. The Denton Development Code
(DDC) is the primary planning document and lays out policies and procedures for zoning and
subdivision regulations. Once a project receives initial approval for development, the developers
will begin doing a detailed engineering design. The DCM is a technical engineering document
which establishes appropriate design methods and provides required criteria for infrastructure
constructed within the City.
Periodic updates to the DCM are required to keep pace with modern development practices,
emerging technologies, and regulatory changes. In July 2024, the Solid Waste and Recycling
Criteria Manual, Stormwater Design Criteria Manual, Transportation Design Criteria Manual,
Water and Wastewater Criteria Manual, and the Streetlight Design Criteria were updated to
combine the five manuals into a single document, formatted to be uniform and consistent with the
DDC. Following this significant update to the design document, Staff is proposing some additional
updates to increase options for development within the City while ensuring all public infrastructure
is designed and constructed to a high quality.
Due to the significant impact the DCM updates have on both private development and City capital
projects, these proposed updates have been accompanied by a significant public outreach and
internal coordination effort. In September 2025, notice that revisions to the DCM were beginning
was sent out to the development community. There was also a series of internal meetings, which
included representatives from all departments, to review the current DCM, discuss suggested
changes, and make a recommendation for modifications. This draft update was posted online in
October 2025 for public review with a link to provide comments. Proposed updates were also
presented and discussed across various venues, including developer town hall and professional
engineering organizational meetings. In addition to these outreach efforts, the proposed updates
were presented to the Planning and Zoning Commission, the Public Utility Board, and the Mobility
Committee. Updates are scheduled for a public hearing and adoption on January 13, 2026, with an
effective date of February 1, 2026.
DISCUSSION:
Notable updates to each section of the DCM are discussed below:
Solid Waste
December 19, 2025 Report No. 2026-014
There are limited proposed updates to the Solid Waste section of the DCM. The only notable
change is the inclusion of additional guidance for the design of side-load enclosures for use in
situations where site constraints will not accommodate typical front-load enclosures.
Stormwater Design
Under the stormwater design section of the DCM, staff is proposing to add polypropylene as an
acceptable material for pipe in the public stormwater collection system. Currently, the only
permissible material is a reinforced concrete pipe and staff have received multiple comments to
investigate alternative materials. Staff conducted an investigation over approximately a year into
alternative materials and consulted multiple vendors, met with other municipalities to discuss their
experiences, and observed active construction using polypropylene pipe. Following this
investigation, staff are confident that polypropylene pipe is a material with many appropriate
applications within the public stormwater collection system and will allow for greater flexibility
in development and lower costs in city projects while still maintaining high-quality public
infrastructure.
Another significant proposed update to the stormwater design section is the requirement to remove
suspended solids (sediment) from drainage runoff before the stormwater exits the site. The 2024
DCM included this practice only as a recommendation rather than a requirement. Staff is proposing
to make this a requirement which would only apply to runoff from impervious surfaces and
developments disturbing more than one acre. Removing this sediment from stormwater before it
enters the public collection system has several benefits, including reducing the maintenance cost
and frequency of cleaning required in the downstream public stormwater system. This change also
aligns the City with regional NCTCOG guidance and EPA regulations currently effective in other
states, and anticipated to become effective in Texas in the future. This change would also benefit
development by allowing greater flexibility in how storm water quality may be addressed and
could result in smaller detention basins and therefore larger developable area.
Water/Wastewater
Many of the proposed changes to the water/wastewater section of the criteria manual are centered
around reorganization of the existing requirements for improved readability and information
organization. Some additional criteria proposed in this update would require geotechnical
investigations and cathodic protection of metal pipes. This is due to the potential of corrosive soils
within the City, which can greatly shorten the lifespan of metal pipe if the hazardous soils are not
identified and cathodic protection is not provided. The updated regulations include additional lift
station design criteria are being proposed to improve planning, emergency provisions, and station
monitoring.
Transportation
Several notable changes are also being proposed to the transportation section of the manual.
Additional guidance on traffic calming measures is proposed to clarify which measures are
appropriate, such as chicanes, and establish the necessary coordination with emergency services.
New restrictions on perpendicular and angled street parking are proposed, as these parking
configurations can potentially be less safe than parallel parking. Updates are also proposed to
establish a new street classification - ‘Major Collector’ and update the roadway geometry standards
December 19, 2025 Report No. 2026-014
accordingly. All updates to the transportation criteria align with the City of Denton's Vision Zero
best practices and objectives for enhancing road safety. These updates prioritize the safety of all
road users by emphasizing the design of transportation facilities to reduce crashes and improve
safety for cyclists, pedestrians, micromobility users, and those using mobility-on-demand services,
while ensuring full compliance with the Americans with Disabilities Act (ADA).
Streetlights
Minimal updates are proposed in the streetlight section of the design criteria manual. The inclusion
of a new streetlight pole style is being proposed, along with guidance to clarify the process for
requesting the addition or removal of street lighting in an area.
Environmentally Sensitive Areas
A new section dedicated to environmentally sensitive areas is proposed in these updates. This
section is a consolidation of institutional knowledge meant to clarify the process of how
environmentally sensitive areas are to be identified, assessed, and preserved or restored.
ATTACHMENTS:
Proposed Design Criteria Manual – redline copy
Proposed Design Criteria Manual – clean copy
STAFF CONTACT:
Mike Linder
Senior Engineer – Engineering
Mike.Linder@cityofdenton.com
(940)-349-8942
PARTICIPATING DEPARTMENTS: Engineering
STAFF TIME TO COMPLETE REPORT: 4 hours
Design Criteria Manual
Published: July January 20264
Design Criteria Manuals i
Published: Januaryuly 20264
Table of Contents
Section 1: Introduction........................................................................................... 1
1.1 Title and Effective Date ....................................................................................................... 1
1.2 Purpose ................................................................................................................................. 1
1.3 Organization ......................................................................................................................... 1
Section 2: Abbreviations and Definitions ............................................................ 2
2.1 Abbreviations ....................................................................................................................... 2
2.2 Definitions ............................................................................................................................. 6
Section 3: Solid Waste Design Criteria ............................................................... 20
3.1 Overview ............................................................................................................................. 20
3.2 Design Standards ............................................................................................................... 20
3.2.1 General ............................................................................................................................................................................................ 20
3.2.2 Container Enclosure and Storage Space Dimensional Requirements .................................................................. 21
3.2.3 Container Enclosure Design Requirements...................................................................................................................... 23
3.2.4 Enclosure Access, Placement, Ingress, and Egress Requirements .......................................................................... 23
3.2.5 Alleyway Access ........................................................................................................................................................................... 25
Section 4: Stormwater Design Criteria ............................................................... 27
4.1 Overview ............................................................................................................................. 27
4.1.0 Organization ................................................................................................................................................................................. 27
4.2 Design Focus ....................................................................................................................... 28
4.3 Design Storms.................................................................................................................... 28
4.4 Hydrologic Methods .......................................................................................................... 29
4.4.1 Types of Hydrologic Methods ............................................................................................................................................... 29
4.4.2 Rainfall Estimation ...................................................................................................................................................................... 30
4.5 Acceptable Downstream Conditions for Open Channels and Floodplains ................... 30
4.5.1 Downstream Assessments ....................................................................................................................................................... 30
4.5.2 Adverse Impacts .......................................................................................................................................................................... 31
4.5.3 Stormwater Diversions .............................................................................................................................................................. 32
4.5.4 Streambank Protection ............................................................................................................................................................. 32
4.5.5 Flood Mitigation .......................................................................................................................................................................... 33
4.6 Stormwater System Design ............................................................................................... 34
4.6.1 Introduction ................................................................................................................................................................................... 34
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits ...................................................................................... 34
4.6.3 Open Channels ............................................................................................................................................................................. 49
4.7 Culverts................................................................................................................................ 53
4.7.1 Design Frequency ....................................................................................................................................................................... 53
4.7.2 Design Criteria .............................................................................................................................................................................. 53
4.7.3 Driveway Culverts........................................................................................................................................................................ 54
4.8 Bridges................................................................................................................................. 55
4.8.1 Design Frequency ....................................................................................................................................................................... 55
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4.8.2 Design Criteria .............................................................................................................................................................................. 55
4.8.3 Other Criteria ................................................................................................................................................................................ 56
4.9 Detention Facilities ............................................................................................................ 56
4.9.1 Design Requirements ................................................................................................................................................................ 56
4.9.2 Design Criteria for Above Grade Detention Facilities .................................................................................................. 56
4.9.3 Design Criteria for Underground Detention Facilities ................................................................................................. 58
4.9.4 Design Criteria for Parking Lot Detention ........................................................................................................................ 59
4.9.5 Design Criteria for Pumped Detention .............................................................................................................................. 60
4.9.6 Outlet Structures for Detention Facilities ......................................................................................................................... 60
4.10 Energy Dissipation ............................................................................................................. 63
4.10.1 Design Frequency ....................................................................................................................................................................... 63
4.10.2 Design Criteria .............................................................................................................................................................................. 63
4.10.3 Recommended Energy Dissipater for outlet protection............................................................................................. 63
4.11 Floodplain ........................................................................................................................... 63
4.11.1 Floodplain Development Criteria ......................................................................................................................................... 63
4.11.2 Procedures for Floodplain Alteration ................................................................................................................................. 67
4.11.3 Fully Developed Water Surface Elevation Calculations ............................................................................................... 68
4.11.4 Floodplain Alteration Guidelines .......................................................................................................................................... 68
4.12 Drainage and Floodplain Easements ................................................................................ 69
4.12.1 General ............................................................................................................................................................................................ 69
4.12.2 Storm Drain Easements ............................................................................................................................................................ 69
4.12.3 Channel Access ............................................................................................................................................................................ 70
4.12.4 Detention Facilities Easements .............................................................................................................................................. 71
4.12.5 Post-Construction Water Quality Control Structure Easements ............................................................................. 71
4.12.6 Fences .............................................................................................................................................................................................. 71
4.13 Water Quality...................................................................................................................... 71
4.13.1 Water Quality Protection Volume ........................................................................................................................................ 71
4.13.2 Water Quality Hotspots ............................................................................................................................................................ 72
4.13.3 Required Stormwater Facility Maintenance Agreements ........................................................................................... 72
4.13.4 Construction Erosion and Sediment Control Requirements ..................................................................................... 73
4.14 Stormwater Facility Maintenance Agreements .............................................................. 81
4.14.1 Maintenance Agreements ....................................................................................................................................................... 81
4.14.2 Private Maintenance (SWFMA Required) .......................................................................................................................... 81
4.14.3 Maintenance Agreement Requirements ........................................................................................................................... 82
Section 5: Transportation Design Criteria ......................................................... 84
5.1 Overview ............................................................................................................................. 84
5.1.1 Organization ................................................................................................................................................................................. 84
5.2 Mobility Framework ........................................................................................................... 85
5.2.1 Roadway Classification ............................................................................................................................................................. 85
5.2.2 Auxiliary Roadway Classifications ......................................................................................................................................... 87
5.3 Roadway Design ................................................................................................................. 88
5.3.1 Design Controls ........................................................................................................................................................................... 88
5.3.2 Street Sections.............................................................................................................................................................................. 89
5.4 Intersection Design ............................................................................................................ 91
5.4.1 Geometry ........................................................................................................................................................................................ 91
5.4.2 Visibility Standards ..................................................................................................................................................................... 92
5.4.3 Vertical Curve Standards .......................................................................................................................................................... 93
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5.4.4 Turn Lane Requirements .......................................................................................................................................................... 94
5.4.5 Intersection Detail for Collectors and Arterials .............................................................................................................. 97
5.4.6 Intersection Spacing .................................................................................................................................................................. 98
5.4.7 Roundabouts ................................................................................................................................................................................ 98
5.5 Auxiliary Roadway Design ................................................................................................. 99
5.5.1 Alleys ................................................................................................................................................................................................ 99
5.5.2 Drives ............................................................................................................................................................................................... 99
5.5.3 Cul-de-sacs .................................................................................................................................................................................. 108
5.5.4 Supplementary Design Elements ....................................................................................................................................... 111
5.6 Access Management ........................................................................................................ 116
5.6.1 Purpose and Goals.................................................................................................................................................................... 116
5.6.2 Access Standards....................................................................................................................................................................... 116
5.6.3 Fire Apparatus Access Roads ............................................................................................................................................... 119
5.7 Bike and Pedestrian Facility Design ............................................................................... 121
5.7.1 Mobility Plan Component ..................................................................................................................................................... 121
5.7.2 Accessibility Standards ........................................................................................................................................................... 121
5.7.3 Geometric Standards ............................................................................................................................................................... 121
5.7.4 Intersection .................................................................................................................................................................................. 122
5.7.5 Signage and Pavement Markings ...................................................................................................................................... 123
5.7.6 Amenities ...................................................................................................................................................................................... 123
5.8 Transit Facility Design ...................................................................................................... 125
5.8.1 General .......................................................................................................................................................................................... 125
5.8.2 Bus Stop Placement ................................................................................................................................................................. 126
5.8.3 Bus Stop Amenities .................................................................................................................................................................. 127
5.8.4 Bus Stop Signage and Markings ......................................................................................................................................... 127
5.9 Traffic Impact Analysis Guidelines ................................................................................. 127
5.9.1 General .......................................................................................................................................................................................... 127
5.9.2 Preliminary Trip Generation Assessment ........................................................................................................................ 128
5.9.3 When is a TIA required? ......................................................................................................................................................... 128
5.9.4 TIA Requirements ...................................................................................................................................................................... 129
5.9.5 Submission and Review Procedures ........................................................................ Error! Bookmark not defined.
5.9.6 Safety Assessment .................................................................................................................................................................... 136
5.9.7 Bike/Ped TIA ................................................................................................................................................................................ 138
5.10 Pavement Design Standard ............................................................................................. 141
5.10.1 Streets ............................................................................................................................................................................................ 141
5.10.2 Drive Approach .......................................................................................................................................................................... 141
5.11 Complete and Context-Sensitive Streets ....................................................................... 141
Section 6: Water and Wastewater Design Criteria ......................................... 143
6.1 Overview ........................................................................................................................... 143
6.2 Water Design Guidelines ................................................................................................. 144
6.2.1 Water Main Separation from Wastewater Mains ............................................... Error! Bookmark not defined.
6.2.2 Size of Water Distribution Mains ........................................................................................................................................ 144
6.2.3 Depth of Cover for Water Mains ........................................................................................................................................ 149
6.2.4 Pipe and Fittings ........................................................................................................................................................................ 149
6.2.5 Meters and Meters Cans/Vaults ......................................................................................................................................... 155
6.2.6 Water Main Horizontal and Vertical Alignment .................................................. Error! Bookmark not defined.
6.2.7 Highway Crossings ................................................................................................................................................................... 165
6.2.8 Railroad Crossings .................................................................................................................................................................... 165
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6.2.9 Creek Crossings ......................................................................................................................................................................... 165
6.2.10 Tunneling, Boring, Jacking and Casing ................................................................... Error! Bookmark not defined.
6.2.11 Elevated Crossings .................................................................................................................................................................... 165
6.2.12 Underground Utility Crossing ..................................................................................... Error! Bookmark not defined.
6.2.13 Fence or Wall Crossings ................................................................................................ Error! Bookmark not defined.
6.2.14 Existing Water Main Replacement ..................................................................................................................................... 166
6.2.15 Methods of Connection ................................................................................................ Error! Bookmark not defined.
6.2.16 Valves .................................................................................................................................... Error! Bookmark not defined.
6.2.17 Dead-End Mains ............................................................................................................... Error! Bookmark not defined.
6.2.18 Fire Hydrant Locations and Coverage ..................................................................... Error! Bookmark not defined.
6.2.19 Requirements for Abandoning Water Mains ....................................................... Error! Bookmark not defined.
6.2.20 Flushing and Disinfection ............................................................................................. Error! Bookmark not defined.
6.3 Wastewater Design Guidelines ....................................................................................... 168
6.3.1 Estimated Wastewater Flows................................................................................................................................................ 168
6.3.2 Separation between Water and Wastewater Collection Facilities ............... Error! Bookmark not defined.
6.3.3 Size and Slope of Sewers ....................................................................................................................................................... 169
6.3.4 Sewer Main Depth .................................................................................................................................................................... 171
6.3.5 Recommended Cover .............................................................................................................................................................. 171
6.3.6 Sewer Alignment .............................................................................................................. Error! Bookmark not defined.
6.3.7 Sewer Laterals ............................................................................................................................................................................. 171
6.3.8 Gravity and Force Main Sewer Pipe Material ................................................................................................................ 172
6.3.9 Sewer Pipe Embedment ......................................................................................................................................................... 173
6.3.10 Manholes ...................................................................................................................................................................................... 173
6.3.11 Highway Crossings ................................................................................................................................................................... 175
6.3.12 Railroad Crossings .................................................................................................................................................................... 175
6.3.13 Tunneling, Borings, Jacking, and Casing ................................................................ Error! Bookmark not defined.
6.3.14 Underground Utility Crossings ............................................................................................................................................ 174
6.3.15 Fence or Wall Crossings ................................................................................................ Error! Bookmark not defined.
6.3.16 Creek Crossings ................................................................................................................ Error! Bookmark not defined.
6.3.17 Siphons ................................................................................................................................. Error! Bookmark not defined.
6.3.18 Abandonment of Sewer Mains ............................................................................................................................................ 176
6.3.19 Abandonment of Manholes.................................................................................................................................................. 176
6.3.20 Lift Stations .................................................................................................................................................................................. 177
6.3.21 Low-Pressure or Alternative Collection Systems ......................................................................................................... 184
6.3.22 On-Site Sewage Facilities ....................................................................................................................................................... 184
6.3.23 Grease Traps / Grit Traps ....................................................................................................................................................... 185
6.3.24 Inspections Required ............................................................................................................................................................... 190
6.4 Construction Plans ........................................................................................................... 191
6.4.1 General .......................................................................................................................................................................................... 191
6.4.2 Responsibility .............................................................................................................................................................................. 191
6.4.3 Format............................................................................................................................................................................................ 191
6.4.4 Plan Requirements.................................................................................................................................................................... 191
Section 7: Streetlight Design Criteria ............................................................... 193
7.1 Overview ........................................................................................................................... 193
7.1.1 Applicability ................................................................................................................................................................................. 193
7.1.2 Organization ............................................................................................................................................................................... 193
7.2 Requirements .................................................................................................................... 194
7.2.1 General .......................................................................................................................................................................................... 194
7.2.2 Roadway Lighting Requirements ....................................................................................................................................... 194
7.2.3 Installation Requirements ...................................................................................................................................................... 199
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7.2.4 Construction Requirements .................................................................................................................................................. 206
7.3 Developer and DME Responsibilities ............................................................................. 206
7.3.1 Highways and Streets (except local residential streets with speed ≤ 30 mph) .............................................. 206
7.3.2 Local Residential Streets (with speed limits ≤ 30mph) ............................................................................................. 207
7.3.3 Streetlighting in Non-DME-Served Areas ...................................................................................................................... 208
7.3.4 Customer/Citizen Requests for addition/removal of Streetlighting .................................................................... 208
Section 8: Design Deviations .................................... Error! Bookmark not defined.
8.1 Overview ................................................................................... Error! Bookmark not defined.
8.1.1 General ................................................................................................................................. Error! Bookmark not defined.
8.2 Design Deviation Procedure ................................................... Error! Bookmark not defined.
8.3 Revocation of an Approved Design Deviation ...................... Error! Bookmark not defined.
Appendix A: Example Stormwater Facility Checklists .................................... 218
Appendix B: Design Deviation Request Form ................................................. 224
Appendix C: Poles and Luminaires - Standard Lighting Fixtures ................. 228
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Section 1: Introduction
1.1 Title and Effective Date
1.1.1 This document is the Design Criteria Manual of the City of Denton, Texas. It shall be officially known
and cited as the “Denton Design Criteria Manual,” and is referred to internally in this document as “this
DCM” and “this Manual.”
1.1.2 This DCM shall become effective on JanuaryJuly 1, 20264.
1.2 Purpose
The purpose of the Denton Design Criteria Manual (DCM) is to provide minimum, non-exhaustive guidelines
for the design and construction of solid waste, stormwater, transportation, water and wastewater, and
streetlight infrastructure within the City of Denton, Texas and its extraterritorial jurisdictions. The criteria
established in this Manual have been developed from a review of various applicable publications, regulatory
requirements, and City of Denton offices which oversee the design, construction and maintenance of the
facilities.
These guidelines are to be used by design engineers in the City of Denton Capital Projects and Engineering
Departmentivision, consulting engineers employed by the City, and engineers of subdivision and land
development infrastructure projects proposed for construction and acceptance by the City, within the City
and its extraterritorial jurisdictions.
Along with this Manual, the Denton Development Code (DDC) and relevant submittal checklists should be
consulted for additional criteria. The criteria established in this Manual do not supersede the criteria
contained in the DDC. In the case of conflict among this Manual, City of Denton Standard Details, or other
cited regulations and standards, the more stringent requirement shall apply.
This DCM is not intended to be an all-inclusive design document for all circumstances and conditions. The
DDC and City of Denton Code of Ordinances must be consulted for possible impacts to the proposed
design. The Federal Government, the State of Texas, NCTCOG, Denton County, Denton County Transit
Authority (DCTA), and other related organizations and resources should be consulted for additional criteria,
as may be deemed necessary.
1.3 Organization
In addition to the design criteria established in this DCM, guidance is also provided for design deviations
from the required design criteria. The contents of this Manual are categorized into sections shown below:
A. Section 1: Introduction
B. Section 2: Abbreviations and Definitions
C. Section 3: Solid Waste Design
D. Section 4: Stormwater Design
E. Section 5: Transportation Design
F. Section 6: Water and Wastewater Design
G. Section 7: Streetlight Design Criteria
H. Section 8: Design Deviations
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Section 2: Abbreviations and Definitions
2.1 Abbreviations
AASHTO American Association of State Highway and Transportation Officials
ADA Americans with Disabilities Act
APBP Association of Pedestrian and Bicycle Professionals
ASTM American Society for Testing and Materials
AWSC All-Way Stop Control
AWWA American Water Works Association
BFE Base Flood Elevation
BFR Barrier Free Ramp
BOC Back of Curb
BMP Best Management Practices
CCN Certificate of Convenience and Necessity
cfs cubic feet per second
CLOMR Conditional Letter of Map Revision
COA Condominium Owner’s Association
CP Cathodic Protection
cu. ft. cubic feet
cu. in. cubic inches
DCAD Denton Central Appraisal District
DCM Design Criteria Manual
DCTA Denton County Transit Authority
DDC Denton Development Code
DFW Dallas-Fort Worth Metroplex
DIP Ductile-Iron Pipe
DRP Development Review Process
DSA Down Stream Assessment
EOL End-of-Line
ESA Environmentally Sensitive Area
ft. foot or feet
FEMA Federal Emergency Management Agency
FFE Finished Floor Elevation
Section 2: Abbreviations and Definitions
2.1 Abbreviations
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FHWA Federal Highway Administration
FIRM Federal Insurance Rate Map
FIS Flood Insurance Study
FM Farm to Market
fps feet per second
FSE Food Service Establishment
gal. gallon(s)
GPCD gallons per capita per day
GPD gallons per day
GPM gallons per minute
GPS Global Positioning System
HDPE High Density Polyethylene
HEC-HMS Hydrologic Engineering Center’s Hydrologic Modeling System
HEC-RAS Hydrologic Engineering Center's River Analysis System
HGI Hydromechanical Grease Interceptor
HGL Hydraulic Grade Line
HOA Home Owners’ Association
IBC International Building Code
ID Inner Diameter
IFC International Fire Code
IH Interstate Highway
in. inch(es)
IPC International Plumbing Code
ITE Institute of Transportation Engineers
iSWMTM Integrated Stormwater Management
kg. kilogram(s)
lb. pound or pounds
LOMR Letter of Map Revision
LOS Level-of-Service
MEP Mechanical, Electrical, and Plumbing
MGD Million Gallons per Day
mL milli-liter(s)
mph miles per hour
Section 2: Abbreviations and Definitions
2.1 Abbreviations
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NAVD North American Vertical Datum
NCHRP National Cooperative Highway Research Program Report
NCTCOG North Central Texas Council of Governments
NFIP National Flood Insurance Program
NFPA National Fire Protection Association
NGVD National Geodetic Vertical Datum
NOAA National Oceanic and Atmospheric Administration
PE Professional Engineer
PHT Peak-Hour Trips
PMF Probable Maximum Flood
PMP Probable Maximum Precipitation
POA Property Owners’ Association
POTW Publicly Owned Treatment Works
PROWAG Public Rights of Way Accessibility Guidelines
psi pounds per square inch
PUCT Public Utilities Commission of Texas
PUE Public Utility Easement
PVC Polyvinyl Chloride
PZC Planning and Zoning Commission
RCP Reinforced Concrete Pipe
ROW Right-of-Way
RPBA Reduced Pressure Backflow Assembly
SCADA Supervisory Control and Data Acquisition
SCS Soil Conservation Service
SDR Standard Dimension Ratio
SFE Single-Family Equivalent
SETP-PD Safety End Treatment Plan – Parallel Drainage
SFHA Special Flood Hazard Area
SH State Highway
sq. ft. square feet
sq. mi. square mile(s)
SWFMA Stormwater Facility Maintenance Agreement or Maintenance Agreement
TAC Texas Administrative Code
Section 2: Abbreviations and Definitions
2.1 Abbreviations
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TAS Texas Accessibility Standards
TCEQ Texas Commission on Environmental Quality
TDLR Texas Department of Licensing and Registration
TGA Trip Generation Assessment
TIA Traffic Impact Analysis
TMUTCD Texas Manual on Uniform Traffic Control Devices
TSS Total Suspended Solids
TxDOT Texas Department of Transportation
U.S. United States of America
USACE United States Army Corps of Engineers
USGS United States Geological Survey
VPD Vehicle-trips per day
WOTUS Waters of the United Stated of America
WMP Water Master Plan
WSEL Water Ssurface Eelevation
w.s.f.u. Water-Supply Fixture-Unit(s)
ZOI Zone of Influence
Section 2: Abbreviations and Definitions
2.2 Definitions
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2.2 Definitions
20-Year Horizon
The estimated traffic volume for the study area based on a 20-year growth period.
100-year Event
Event (rainfall or flood) that has a 1% chance of being equaled or exceeded in any given year.
Abutment
A wall supporting the end of a bridge or span and sustaining the pressure of the bordering earth.
Applicant
Any firm, entity, partnership, company, public utility company, or individual that submits a formal request
or application.
Apron
A floor or lining of concrete, timber, or other suitable material at the toe of a dam, entrance or discharge
side of a spillway, a chute, or other discharge structure, to protect the waterway from erosion from falling
water or turbulent flow.
Area of Special Flood Hazard
The area designated as subject to flooding from the 1% chance flood on the flood insurance rate map. For
purposes of these criteria, the term "special flood hazard area" is synonymous in meaning with the phrase
"area of special flood hazard" and may be ref erred to as "SFHA".
Backwater
The rise of the water level upstream due to an obstruction or constriction in the channel.
Backwater Curve
The term applied to the longitudinal profile of the water surface in an open channel when flow is steady but
non-uniform.
Baffles
Deflector vanes, guides, grids, gratings, or similar devices constructed or placed in flowing water, to: (1)
check or effect a more uniform distribution of velocities; (2) absorb energy; (3) divert, guide, or agitate the
stormwater flow; and (4) check eddy currents.
Baffle Chute
A drop structure in a channel with baffles for energy dissipation to permit the lowering of the hydraulic
energy gradient in a short distance to accommodate topography.
Base Flood Elevation
The elevation shown on the Flood Insurance Rate Map (FIRM) and found in the accompanying Flood
Insurance Study (FIS) for Zones A, AE, AH, A1-30, AR, V1-30, or VE that indicates the water surface elevation
resulting from the flood that has a 1% chance of equaling or exceeding that level in any given year.
Section 2: Abbreviations and Definitions
2.2 Definitions
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Calibration
Process of checking, adjusting, or standardizing operating characteristics of instruments and model
appurtenances on a physical model or coefficients in a mathematical model. The process of evaluating the
scale readings of an instrument in terms of the physical quantity to be measured.
Carrier Pipe
A pipe used to carry stormwater, water, or wastewater, as opposed to an exterior protective casing pipe.
Casing Pipe
An exterior protective pipe that encases a carrier pipe for various types of crossings, including roadways,
creeks, and railroads. Also known as encasement pipe.
Channel
A man-made drainageway or watercourse, generally constructed to straighten a stream or increase its
capacity.
Channel Roughness
Irregularities in channel configuration which attenuate the flow of water and dissipate its energy.
Chute
An inclined conduit or structure used for conveying water to a lower level.
City’s Engineer
A Professional Engineer, licensed by the State of Texas, who is the subject matter expert of the relevant
topic of discussion, and employed by the City of Denton.
Conduit
Any open or closed structure for conveying flowing water.
Corner Clip
ROW dedication at intersection corners to provide sufficient room for intersection visibility, pedestrian
access, and other street facilities.
Critical Flow
The state of flow for a given discharge at which the specific energy is a minimum with respect to the bottom
of the conduit. The Froude Number is equal to 1.0 for critical flow conditions.
Crown
The highest point on a transverse section of conduit or the highest point of a roadway cross-section.
Culvert
Large pipe or other conduit through which a small stream passes under a road or street.
Curb
A vertical or sloping structure located along the edge of a roadway, normally constructed integrally with
the gutter, which strengthens and protects the pavement edge and clearly defines the pavement edge to
vehicle operators.
Section 2: Abbreviations and Definitions
2.2 Definitions
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Dam
A barrier constructed across a watercourse for the purpose of creating a reservoir or diverting water from a
conduit or channel.
Degradation
The progressive general lowering of a stream channel by erosion, other than that caused by a constriction.
Department Reviewer
A member of a City of Denton department, designated by the Department Director, with subject matter
expertise related to the Design Criteria Manual who is designated as being responsible for the review of
design deviation requests.
Depression Storage
Collection and storage of rainfall in natural depressions after exceeding infiltration capacity of the soil.
Design Storm or Flood
The storm or flood which is used as the basis for design.
Detention
The storage of storm runoff for a controlled release during or immediately following the design storm.
1. Off-site detention - A detention pond located outside the boundary of the area it serves.
2. On-site detention - A detention pond which is located within and serves only a specific site or
subdivision.
3. Regional detention - Detention facilities provided to control excess runoff based on a watershed -wide
hydrologic analysis.
Development
Any man-made change to improved or unimproved real estate, including but not limited to, buildings or
other structures, paving, drainage, or utilities. Development activities include: subdivision of land;
construction or alteration of structures, roads, parking, fences, pools, signs, temporary uses, utilities, and
other facilities; installation of septic systems; grading; excavation, mining or drilling operations; deposit of
refuse, debris, or fill materials; and clearing of natural vegetative cover (with the exception of agricultural
activities as defined and as permitted). Routine repair and maintenance activities are exempted.
Development Project Facilitation
Division within the City of Denton that assists developers move projects through the City’s various
development review process and authorized to process the review of design deviation requests.
Drop Structures
A sloping or vertical section of a channel designed to reduce the elevation of flowing water without
increasing its velocity.
Energy Dissipaters
Engineered devices such as riprap aprons or concrete baffles placed at the outlet of storm water conveyance
systems for the purpose of reducing the velocity, energy and turbulence of the discharged flow.
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Entrance Head
The head required to cause flow into a conduit or other structure; it includes both entrance loss and velocity
head.
Entrance Loss
Head lost in eddies or friction at the inlet to a conduit, headwall or structure.
Existing Traffic
Existing traffic conditions based on the most recent traffic counts. Existing traffic conditions do not include
the traffic created or associated with the development.
Flash Flood
A flood of short duration with a relatively high peak rate of flow, usually resulting from a high intensity
rainfall over a small area.
Flood Control
The elimination or reduction of flood losses by the construction of flood storage reservoirs, channel
improvements, dikes and levees, by-pass channels, or other engineering works.
Flood Hazard Area
Area subject to flooding by 1% chance floods.
Flood Management or Flood Hazard Mitigation
Any program or activity designed to reduce damages from flooding, including stream erosion.
Floodplain
The area that is subject to flooding from the 1% chance flood. The floodplain includes the regulatory
floodway and floodway fringe.
Floodway
The channel and adjacent lands of a watercourse that must be reserved in order to discharge the base flood
without increasing the water surface elevation more than the regulatory designated height.
Floodway Fringe
The area located within the floodplain and outside the floodway.
Freeboard
The distance between the normal operating level and the top of the side of an open conduit left to allow
for wave action, floating debris, or any other condition or emergency without overtopping the structure.
Frequency (of storms, floods)
Average recurrence interval of events, over long periods of time. Mathematically, frequency is the reciprocal
of the exceedance probability.
Froude Number
A flow parameter, which is a measure of the extent to which gravitational action affects the flow. A Froude
number greater than one (1) indicates supercritical flow and a value less than 1 subcritical flow. The simplest
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form of the Froude number is given by the following equation:
F = V / (g D)0.5 [Eqn. 2.1]
Where: V = Velocity
g = the acceleration due to gravity (32.2 ft/s2)
D = depth
Fully Developed Conditions
A description of hydrologic conditions in a watershed, if the watershed has been completely built out based
on the zoning and future land use maps of the City. If there is no designated future land use, the runoff
coefficient will be assumed to be (0.6) for purposes of determining fully developed water surface elevations.
This term is interchangeable with the term “Ultimate Developed Conditions”. This is not to be confused
with a Developed Floodplain as defined in Subchapter 9.2 of the DDC, which refers to the character of the
streambed itself.
Gabion
A wire container filled with rock and used in the construction of dams, retaining walls, and protection against
erosion.
Grade
1. The inclination or slope of a channel, canal, conduit, etc., or natural ground surface, usually expressed
in terms of the percentage of number of units of vertical rise (or fall) per unit of horizontal distance.
2. The elevation of the invert of the bottom of a conduit, canal, culvert, sewer, etc.
3. The finished surface of a canal bed, road bed, top of an embankment, or bottom of excavation.
Gutter
A generally shallow waterway adjacent to a curb used to convey stormwater.
Headwater
1. The upper reaches of a stream near its sources;
2. The region where ground waters emerge to form a surface stream;
3. The water upstream from a structure.
Hydraulic Control
The hydraulic characteristic which determines the stage-discharge relationship in a conduit. The control is
usually critical depth, tailwater depth, or uniform depth.
Hydraulic Grade Line
A line representing the pressure head available at any given point within the system.
Hydraulic Gradient
A hydraulic profile of the piezometric level of the water, representing the sum of the depth of flow and the
pressure head. In open channel flow, it is the water surface.
Hydraulic Jump
The hydraulic jump is an abrupt rise in the water surface which occurs in an open channel when water
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flowing at supercritical velocity is retarded by water flowing at subcritical velocity. The transition through
the jump results in a marked loss of energy, evidenced by turbulence of the flow within the area of the
jump. The hydraulic jump is sometimes used as a means of energy dissipation.
Hydraulics
A branch of science that deals with practical applications of the mechanics of water movement.
Hydrograph
A graph showing stage, flow, velocity, or other property of water versus time at a given point on a stream
or conduit. Examples include: Dimensionless Unit hydrograph, Unit Hydrograph.
Hydrology
The science dealing with the properties, distribution, and circulation of water on and below the Earth’s
surface and in the atmosphere.
Hyetograph
A histogram or graph of rainfall intensity versus time of storm.
Impervious
A term applied to a material through which water cannot pass or passes with great difficulty.
Infiltration
1. The entering of water through the interstices or pores of a soil or other porous medium.
2. The entrance of water from the ground into a sewer or drain through breaks, defective joints, or porous
walls.
3. The absorption of water by the soil, either as it falls as precipitation, or from a stream flowing over the
surface.
Inlet
Inlets are drainage structures used to collect surface water through grate or curb openings and convey it to
storm drains or direct outlet to culverts.
Inlets used for the drainage of roadway surfaces can be divided into four major classes:
1. Grate Inlets – These inlets include grate inlets consisting of an opening in the gutter covered by one or
more grates, and slotted inlets consisting of a pipe cut along the longitudinal axis with a grate or spacer
bars to form slot openings.
2. Curb-Opening Inlets – These inlets are vertical openings in the curb covered by a top slab.
3. Combination Inlets – These inlets usually consist of both a curb-opening inlet and a grate inlet placed
in a side-by-side configuration, but the curb opening may be located upstream of the grate.
4. Drop Inlet (Y-Inlet) -A storm drain intake structure typically located in unpaved areas. The inlet may
extend above the ground level with openings on one or more sides of the inlet or it may be flush with
the ground with a grated cover.
Intensity
As applied to rainfall, a rate usually expressed in inches per hour.
Interception
As applied to hydrology, refers to the process by which precipitation is caught and held by foliage, twigs,
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and branches of trees, shrubs and buildings, never reaching the surface of the ground, and then lost by
evaporation.
Invert
The floor, bottom, or lowest portion of the internal cross-section of a conduit.
Lag Time
The time difference between two occurrences such as between rainfall and runoff or pumping of a well and
effect on the stream. See Time of Concentration.
Level of Service
A qualitative measure of traffic flow and congestion, representing quality of service. It describes operational
conditions within a traffic stream, generally described in terms of such factors as speed and travel time,
freedom to maneuver, traffic interruptions, comfort and convenience, and safety.
Lining
Impervious material such as concrete, clay, grass, plastic, puddled earth, etc., placed on the sides and bottom
of a ditch, channel, and reservoir to prevent or reduce seepage of water through the sides and bottom
and/or to prevent erosion.
Lip
A small wall on the downstream end of an apron to break the flow from the apron.
Major Stream
Waterways with a contributing drainage area of one square mile or more.
Manning’s Coefficient
The coefficient of roughness used in Manning’s Equation for flow in open channels.
Manning’s Equation
A uniform flow equation used to relate velocity, hydraulic radius and the energy gradient slope.
Median
The portion of a divided roadway separating the opposing traffic flows. A median may be traversable or
non-traversable.
Median Opening
An opening in a non-traversable median that allows accessing or crossing the opposing traffic lanes.
Minimum building elevation
The elevation to which new and substantially improved structures within the floodway or within 200 feet of
the floodplain or SFHA are required to be elevated or floodproofed. This elevation would be equal 18 inches
above the 100-year water surface elevation based on fully developed conditions or 30 inches above the BFE
as indicated in the flood insurance study or, if the BFE is unavailable, 30 inches above the 100-year flood
elevation based on current development watershed conditions.
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Model
Mathematical systems analysis by computer, applied to evaluate rainfall-runoff relationships; simulate
watershed characteristics, predict flood and reservoir routings, or use other aspects of planning.
Nappe
The sheet or curtain of water overflowing a weir or dam. When freely overflowing any given structure, it has
a well-defined upper and lower surface.
Open Channel
A conduit in which water flows with a free surface.
Orifice
1. An opening with closed perimeter, and of regular form in a plate, wall, or partition through which water
may flow.
2. The end of a small tube, such as a Pilot tube, piezometer, etc.
Peak Flow (Peak Rate of Runoff)
The maximum rate of runoff during a given runoff event.
Percolation
To pass through a permeable substance such as ground water flowing through an aquifer.
Permeability
The property of a material which permits movement of water through it when saturated and actuated by
hydrostatic pressure.
Pervious
Applied to a material through which water passes relatively freely.
Pilot Channel
A constructed pathway that guides base streamflow or runoff along a specified route through a drainage
facility or drainage feature.
Porosity
1. An index of the void characteristics of a soil or stratum as pertaining to percolation; degree of
perviousness.
2. The ratio, usually expressed as a percentage, of (a) the volume of the interstices in a given quantity of
material, to (b) the total volume of the material.
Positive Overflow
When the inlets do not function properly, or when the design capacity of the conduit is exceeded, the excess
flow must be conveyed overland along a paved course. This could mean along a street or alley but could
require a concrete flume and the dedication of special drainage easements on private property.
Post-development
The condition of the given site and drainage area after the anticipated development has taken place.
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Precipitation
Any moisture that falls from the atmosphere, including snow, sleet, rain and hail.
Pre-development
The condition of the given site and drainage area prior to development.
Probable Maximum Flood
The flood that may be expected from the most severe combination of critical meteorological and hydrologic
conditions that are reasonably possible in the region.
Probable Maximum Precipitation
The critical depth-duration-area rainfall relationship for a given area during the seasons of the year which
would result from a storm containing the most critical meteorological conditions considered probable of
occurring.
Projected Growth Rate
The estimated growth rate per year for the study area based upon the average growth in the previous 5 -
year period along arterials in the vicinity of the proposed project.
Proposed Site Traffic Volumes
The number of vehicles per day and per hour projected to be generated by the development.
Rainfall Duration
The length of time over which a single rainfall event occurs.
Rainfall Frequency
The average recurrence interval of rainfall events.
Rainfall Intensity
The rate of accumulation of rainfall, usually in inches or millimeters per hour.
Rational Formula
A traditional method of computing peak flow using intensity of the storm rainfall.
Reach
Any length of river or channel. Usually used to refer to sections which are uniform with respect to discharge,
depth, area or slope, or sections between gaging stations.
Recurrence Interval
The average interval of time within which a given event will be equaled or exceeded once. For an annual
series (as opposed to a partial duration series) the probability of occurrence in anyone year is the inverse of
the recurrence interval. Thus, a flood having a recurrence interval of 100 years has a 1% probability of being
equaled or exceeded in any one year.
Regulatory Floodway
The channel of a river or other watercourse and the adjacent land areas that must be reserved in order to
discharge the base flood without cumulatively increasing the water surface elevation more than a
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designated height.
Retention
The storage of a portion or all of the storm runoff for purposes of permanent use of the retained water.
Retention facilities are similar to detention facilities with the main difference being that all of the storm
runoff will not be released to the downstream drainage network.
Return Period
See Recurrence Interval
Reynold’s Number (Re)
A flow parameter which is a measure of the viscous effects on the flow. Typically defined as shown in the
equation below:
Re = (V. D) / v [Eqn. 2.2]
Where: V = Velocity
D = Depth
v = kinematic viscosity of the fluid
Riprap (Revetment)
Forms of bank protection, usually using rock or concrete.
Routing
Routing is a technique used to predict the temporal and spatial variations of a flood wave as it traverses a
river reach or reservoir. Generally, routing technique may be classified into two categories - hydrologic
routing and hydraulic routing.
Right-of-Way
A designated section of a street, sidewalk, alley, waterway or utility easement and/or related facilities, that
is dedicated for municipal usage.
Right-of-Way Width
The shortest horizontal distance between the lines which delineate the right -of-way of a street.
Runoff
That part of the precipitation which reaches a stream, drain, sewer, etc., directly or indirectly.
1. Direct Runoff - The total amount of surface runoff and subsurface storm runoff which reaches stream
channels.
2. Overland Runoff - Water flowing over the land surface before it reaches a definite stream channel or
body of water.
Runoff Coefficient
A decimal number used in the Rational Formula which defines the runoff characteristics of the drainage
area under consideration. It may be applied to an entire drainage basin as a composite representation or it
may be applied to a small individual area such as one residential lot.
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Runoff Total
The total volume of flow from a drainage area for a definite period of time such as a day, month, or a year,
or it may be for the duration of a particular storm.
Scour
The erosive action of running water in streams or channels in excavating and carrying away material from
the bed and banks.
SCS Runoff Curve Number
Index number used by the National Resource Conservation Service, formerly the Soil Conservation Service,
as a measure of the tendency of rainfall to run off into streams rather than evaporate or infiltrate.
Sediment
Material of soil and rock origin transported, carried, or deposited by water.
Sedimentation Basin
A sediment control basin required to catch runoff from common drainage areas with 10 acres or more
disturbed at one time during any phase of development that dewaters from the surface unless infeasible.
Sidewalk
A paved area within the street ROW or sidewalk easement specifically designed for pedestrians and/or
bicyclists.
Sight Distance
The distance visible to the driver of a passenger vehicle measured along the normal travel path of a roadway
from a designated location and to a specified height above the roadway when the view is unobstructed by
traffic.
Slope, Critical
The slope or grade of a channel that is exactly equal to the loss of head per foot resulting from flow at a
depth that will give uniform flow at critical depth; the minimum slope of a conduit which will produce critical
flow.
Slope, Friction
The friction head or loss per unit length of channel or conduit. For uniform flow the friction slope coincides
with the energy gradient, but where a distinction is made between energy losses due to bends, expansions,
impacts, etc., a distinction must also be made between the friction scope and the energy gradient. The
friction slope is equal to the bed or surface slope only for uniform flow in uniform open channels.
Soffit
In a stormwater pipe, the uppermost point of the interior of the pipe wall. The crown is the uppermost point
on the outside of the pipe wall.
Spillway
A waterway in or about a dam or other hydraulic structure, for the overflow of excess water.
Section 2: Abbreviations and Definitions
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Standard Details
A collection of uniform detail drawings of structures or devices adopted as standard construction details by
the City of Denton.
Steady Flow
Open channel flow is said to be steady if the depth of flow does not change or if it can be assumed to be
constant during the time interval of consideration.
Stormwater Facility Maintenance Agreement or Maintenance Agreement
A legal agreement between the City of Denton and a property owner, including HOAs and POAs, for
perpetual maintenance of a structural BMP.
Stream
A natural drainageway that conveys stormwater, may also be referred to as a creek. References to a stream
or creek in this Manual refer to the entire stormwater carrying component of the stream to the limits of the
floodplain, not just to the streambed.
Stilling Basin
Pool of water conventionally used, as part of a drop structure or other structure, to dissipate energy.
Stopping Sight Distance
The distance required by a driver of a vehicle, traveling at a given speed, to bring the vehicle to a stop after
an object on the roadway becomes visible. It includes the distance traveled during driver perception time,
reaction time, and the vehicle braking distance.
Storage Length
The portion of an auxiliary lane required to store the number of vehicles expected to accumulate in the lane
during an average peak period.
Storm Hydrology
The branch of hydrology that concentrates on the calculation of runoff from storm rainfall.
Stormwater Management
The control of storm runoff on-site or on small streams, by means of land use restrictions, detention storage,
erosion control, and/or drainage measures.
Stormwater Model
Mathematical representation of a stormwater network.
Study area
The boundaries of the assessment area as determined by the City’s Engineer.
Subcritical Flow
The Froude Number is less than 1.0 for subcritical flow conditions.
Supercritical Flow
The Froude Number is greater than 1.0 for supercritical flow conditions.
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Tailwater
The depth of flow in the stream directly downstream of a drainage facility.
Time of Concentration
The estimated time in minutes required for runoff to flow from the most remote section of the drainage
area to the point at which the flow is to be determined.
Total Head Line (Energy Line)
A line representing the energy in flowing water. The elevation of the energy line is equal to the elevation of
the flow line plus the depth plus the velocity head plus the pressure head.
Traffic Queue
Vehicles within a storage queue awaiting traffic movement in a single lane, within one traffic signal cycle.
Trash Rack
Racks, gratings, or mesh designed so as to prevent leaves and rubbish from plugging the outlets from a
dam or detention basin.
Trip Distribution
An estimate of the spatial pattern of trips or other flows between given sets of origins and destination pairs.
Trip distribution models connect the trip origins and destination, estimated by the trip generation models
to create estimated trips based on the Base year and Buildout years (24 hour counts or turning movement
counts). Different trip distribution models are developed for each of the trip purposes for which trip
generation has been estimated.
Trunk Line
The main line of a storm drain system extending from manhole to manhole or from manhole to outlet
structure.
TxDOT Highways
State-operated highways that include Farm to Market (FM) roadways, State Highways (SH), Interstate
Highway (IH), IH Frontage Roads, and United States (US) Highways.
Uniform Channel
A channel with a constant cross-section and roughness.
Uniform Flow
Open channel flow is said to be uniform if the depth of flow is the same at every section of the channel.
Unit Hydrograph
The direct runoff hydrograph resulting from one inch of precipitation excess distributed uniformly over a
watershed for a specified duration.
Valley Storage
Refers to the water storage capacity of a stream and is a volume that is measured below the base flood
elevation. Restrictions on loss of valley storage refer to compensation for the loss of storage caused by fill
below the base flood elevation.
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Velocity Head
The energy per unit weight of water due to its velocity (v). The velocity head also represents the vertical
distance water must fall freely under gravity to reach its velocity (v). The velocity head can be computed
from the following equation:
Velocity Head = v2 / 2 g [Eqn. 2.3]
Where: v = velocity
g = acceleration due to gravity (32.2 ft/s2)
Water Year
The water year commonly used in the United States is the period from October 1 to September 30 of the
following calendar year.
Watershed
The area contributing storm runoff to a stream or drainage system. Other terms are drainage area, drainage
basin and catchment area.
Zone of Influence
A point downstream where the increased discharge from a proposed development results in 0.00’ increase
in flood elevation.
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Section 3: Solid Waste Design Criteria
3.1 Overview
The purpose of Section 3 - Solid Waste Design Criteria of this DCM is to provide basic criteria and standards
for the development and maintenance of solid waste and recycling container enclosures.
The Solid Waste Design Criteria established in this Manual shall apply as set forth in:
A. City of Denton Code of Ordinances – Chapter 24,
B. DDC Subchapter 7, Section 7.2 – Applicability, and
C. DDC Subchapter 7, Section 7.12 – Solid Waste and Recycling Design Standards.
The City Code of Ordinances states that the City of Denton shall be the exclusive provider of solid waste
collection and disposal services within the City Limits including, but not limited to, services provided for
preconstruction activities, construction activities, and residential, multifamily, and commercial activities.
All contractors and sub-contractorssubcontractors should call City of Denton Customer Service (940-349-
8700) to initiate service. Third-party solid waste providers may not be used for any on-site solid waste
services within the City Limits.
3.2 Design Standards
3.2.1 General
A. Nonresidential on-site solid waste and recycling container enclosures shall be located on each
platted lot of non-residential property and shall be constructed and maintained by the property
owner or developer and made available for use by the City of Denton Solid Waste Department or
commercial recycling service provider.
B. Nonresidential on-site solid waste and recycling container enclosures shall be available for the
storage of all municipal solid waste and recyclables generated for each platted property. The City
reserves the ability to determine whether any parcel or area (fFor example, Downtown Square, strip
centers, multifamily residential, etc.) must have shared container service or an alternative service.
Container enclosures shall be of adequate size to contain all solid wastes, liquid wastes, and
recyclables generated on the property, including, but not limited to, municipal solid waste,
recyclables, grease and oils, process by-products and wastes, hazardous waste, medical waste, and
any special wastes, contained in accordance with Chapter 24, City of Denton Code of Ordinances.
C. The container enclosures shall meet the Container Enclosure and Storage Space Dimensional
Requirements prescribed in Section 3.2.2 of this Manual, as well as Chapter 469 of the Texas
Government Code, as amended.
D. New nonresidential uses of 999 square feet (“sq. ft.") or less will be evaluated by City staff to
determine the applicability of constructing an enclosure. Trash and recycling carts may be
appropriate, thereby eliminating the need for the construction of an enclosure.
E. Cart storage may be utilized on property converted from a residential to non-residential use if the
converted property is a structure of less than 2,500 gross sq. ft., has a waste generation rate
applicable for cart service, and is in an area where commercial cart service is available.
F. Proposed future building expansion (evaluated at 50% or more of the current square footage) and
Section 3: Solid Waste Design Criteria
3.2 Design Standards
3.2.2 Container Enclosure and Storage Space Dimensional Requirements
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phased development shall be considered in site design with regards to sizing, location(s), and
access of future solid waste and recyclables container enclosures. Solid waste and recycling areas
necessary for future building expansion shall be available , but need not be utilized, nor container
enclosures constructed, until future building expansion occurs.
G. Containers for solid waste and recycling service shall be screened from the public right-of-way
(“ROW”) and from adjacent property owners.
H. Proper construction of the container enclosures shall be completed prior to final approval of the
development or property by the City’s Solid Waste Department.
I. Container enclosure designs shall be consistent with the engineering drawings and specifications
shown in the Solid Waste and Recycling Container Enclosure Construction Drawings in the City of
Denton Standard Details.
3.2.2 Container Enclosure and Storage Space Dimensional Requirements
A. All single front-load commercial container enclosures shall have inside walls with dimensions
measuring a minimum of 13 feet wide and 11.5 feet deep. The rRear face of the bollard must be
three (3) feet from the rear of the enclosure and the front of the bollard must be eight (8) feet from
the front of the enclosure, leaving six (6) inches of space equal to the size of the bollard. Only solid
waste and recycling containers are allowed in the enclosures. Other storage containers such as
grease and oil receptacles, and other items shall be stored and located in a different enclosure.
These enclosures shall be located where they will not impede the service of the solid waste and/or
recycling containers.
B. All dual front-load commercial container enclosures shall have inside walls with dimensions
measuring 26 feet wide and 11.5 feet deep. The rRear face of the bollard must be three (3) feet
from the rear of the enclosure and the front of the bollard must be eight (8) feet from the front of
the enclosure, leaving six (6) inches of space equal to the size of the bollard. Only solid waste and
recycling containers are allowed in the enclosures. Other storage containers such as grease and oil
receptacles, and other items shall be stored and located in a different enclosure. These enclosures
shall be located where they will not impede the service of the solid waste and/or recycling
containers.
C. For extremextreme cases and with department director aprovalapprovalIn the rare case where it is
not possible to fit typical front-load enclosures as required above, a design deviation request may
be submitted to the City’s Solid Waste Department for the consideration of the following two
alternatives: citations 1. and 2. are available for consideration. These two options are not included
in Table 3.2can be considered.
1. SAll single side-load commercial container enclosures shall havehaving inside walls with
dimensions measuring a minimum of 10 feet wide and eight (8) feet deep. The Rear face of
the bollard must be one (1) foot from the rear of the enclosure, and the front of the bollard
must be 6 feet 6 inches6.5 feet from the front of the enclosure, leaving six (6) inches of space
equal to the size of the bollard. Only solid waste and recycling containers are allowed in the
enclosures.
DAll dual side- load commercial container enclosures shall havehaving inside walls with
dimensions measuring 20 feet wide and eight (8) feet deep. The Rear face of the bollard must
be one (1) foot from the rear of the enclosure, and the front of the bollard must be 6 feet, 6
inches6.5 feet from the front of the enclosure, leaving six (6) inches of space equal to the size
Section 3: Solid Waste Design Criteria
3.2 Design Standards
3.2.2 Container Enclosure and Storage Space Dimensional Requirements
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of the bollard. Only solid waste and recycling containers are allowed in the enclosures.
1.2.
B.D. All roll-off compactor enclosures shall have inside walls with dimensions measuring a minimum
of 16 feet wide. The depth of the inside walls must accommodate the compactor size selected.
C.E. The City of Denton Standard Details contain the required construction specifications for container
enclosures and storage spaces.
D.F. All developments shall be required to install container enclosures as specified in Table 3.2-A .
E.G. Nonresidential uses which that are not required to meet the above storage space and enclosure
requirements, will be reviewed for adequate solid waste and recyclables enclosures based on site -
specific information and the following Solid Waste and Recycling Design Factors:
1. Type of business;
2. Waste generation potential;
3. Waste generation of similar businesses;
4. Square footage of the development and structures;
5. Number of floors;
6. Location of the business;
7. Hours of business operation;
8. Business site plan; and
9. Phased development and future use plans.
Table 3.2-A: Minimum Container Enclosure Requirements
Development Use Required Enclosure(s) or Container(s)
RESIDENTIAL
Single-family Residential curbside cart pick-up Townhomes – 4 units orand fewer
RESIDENTIAL - MULTIFAMILY
5 – 48 units 2 front-load containers enclosed
49 – 64 units 3 front-load containers enclosed
65 – 200 units
1 compactor and 1 front-load container for recycling
or
4 front-load containers enclosed
200+ units 1 compactor and 1 front-load containers enclosed
GENERAL COMMERCIAL
1 – 15,000 sq. ft. 2 front-load containers enclosed
15,001 – 50,000 sq. ft. 3 front-load containers enclosed
50,001 – 200,000 sq. ft.
1 compactor and 1 front-load container for recycling
or
4 front-load containers enclosed
Over 200,000 sq. ft. 1 compactor and 1 front-load container enclosed
Section 3: Solid Waste Design Criteria
3.2 Design Standards
3.2.4 Container Enclosure Design Requirements
Design Criteria Manuals 23
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Notes:
[1] For industrial/warehouse development, container(s) do not require enclosures, but container(s) must be screened from public view.
3.2.3 Container Enclosure Design Requirements
A. Materials used for container enclosure construction shall be compatible with the architecture and
appearance of the main building and may include the following materials:
1. Concrete Block – Tinted, colored, painted, or with textured facing;
2. Concrete – Poured or tilt wall construction;
3. Brick - Double brick thickness minimum;
4. Stone;
5. Metal;
6. Wood;
7. Vinyl;
8. Composite Material; or
9. Any combination of materials 1-8.
B. Front-load and side-load commercial enclosures shall have walls constructed to a minimum height
of six (6) feet, or as tall as required to conceal the container. Compactor enclosure walls must be a
minimum height of eight (8) feet, in order to conceal the compactor and mechanical equipment.
C. Gates shall be required when the interior of the enclosure is visible from the public ROW or when
it is visible from the lot of an adjacent property owner.
D. Personal access side gates are recommended as a feature of all gated enclosures. These gates
should be fitted with emergency egress strike bars.
3.2.4 Enclosure Access, Placement, Ingress, and Egress Requirements
A. The required number of enclosures will be determined based on the type and size of the
development.
B. Dumpster enclosures must be angled no more than 30 degrees from the center line of the solid
waste collection vehicle route.
C. There must be 50 feet or more of unobstructed truck access in front of each container.
D. For safety purposes, solid waste collection vehicles will not back up more than 100 feet after
servicing a container and will not make any turns while backing up.
E. Turn Radii Requirements: The turn radii must be a minimum of 30 feet for any intersection to
accommodate occasional turning trucks for weekly pick-up.
F. The collection vehicle will travel through a site once without backtracking. For an example of a
typical solid waste collection route, take note of the Typical Solid Waste Collection Route Schematic
shown in Figure 3.1 below.
G. Container enclosures shall not be located in a fire lanefire apparatus access roads, public ROW,
public utility easements, or sidewalk areas.
Section 3: Solid Waste Design Criteria
3.2 Design Standards
3.2.4 Enclosure Access, Placement, Ingress, and Egress Requirements
Design Criteria Manuals 24
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H. No solid waste container enclosure shall be located within the required front yard or protrude in
front of any buildings along the designated lot frontage.
I. Parking spaces shall begin after the enclosure gates open. No obstructions permitted around
enclosure or gate openings equivalent to the length of the gate.
J. The location of container enclosures may not cause the obstruction of traffic for excessive lengths
of time while being serviced.
K. The solid waste service truck shall be on the property owner’s property during service operations,
if the site design permits.
L. Ingress and egress routes shall be designed to facilitate exiting the property in a forward driving
direction for all interstate and state roads, arterial streets, and collector streets with four lanes. See
the Backing Clearance Schematic in Figure 3.2 below.
M. Utility wires and structure overhangs should have a minimum height clearance of 20 feet along the
ingress and egress route. No utility wires shall extend over the enclosure approach and service area.
N. Container enclosures shall be located a minimum of 30 feet away from any storm drain or drainage
flow areas. Where site configuration allows, container enclosures shall also be placed downslope of
any storm drain.
Figure 3.1 Typical Solid Waste Collection Route Schematic
Section 3: Solid Waste Design Criteria
3.2 Design Standards
3.2.5 Alleyway Access
Design Criteria Manuals 25
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Figure 3.2 Backing Clearance Schematic
3.2.5 Alleyway Access
An alley (residential or commercial) is a private street designed to provide fire and solid waste collection
access to the rear of or side of a lot. Dead -ends are not permitted in alleys. Alleys used for solid waste
collection must comply with the Transportation Design Criteria in Section 5 of this Manual. Alleyway access
must comply with the following criteria:
A. Design Factors:
1. Turn Radius;
2. Street Widths;
3. Horizontal and Vertical Clearances;
4. Pavement; and
5. Multifamily Units
B. Turn Radii Requirements: Texas Department of Transportation (TxDOT) recommends, via AASHTO,
that the turn radii be a minimum of 30 feet for alley-to-alley intersections with occasional turning
trucks for weekly trash pick-up per TCEQ regulations. Turn radii must be sufficient for side-load
residential collection vehicles to navigate alleyways lined with trash and recycle carts on both sides.
See Figure 3.3 below.
C. Alley Width Requirements: Alleys must be paved and a minimum of 15-ft. wide. Additionally, alleys
must be wide enough to accommodate carts, to allow vehicles to safely service carts, and to comply
with the Transportation Design Criteria in Section 5 of this Manual.
D. Horizontal and Vertical Clearance Requirements: Balconies, landscaping, or other elements shall
not encroach into approved horizontal or vertical clearances for vehicle travel, backing, loading, or
other operations along any alley.
1. The horizontal operating travel clearance must be 20 feet.
Section 3: Solid Waste Design Criteria
3.2 Design Standards
3.2.5 Alleyway Access
Design Criteria Manuals 26
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2. The vertical operating travel clearance must be 15 feet.
E. Pavement Requirements: Pavement must be built to standards that allow two (2) 33-ton vehicles to
travel down all alleys twice each service day. Alternatively, a responsible party, HOA, or POA must
provide a waiver recorded with the property for potential damage caused over time by normal
hauler operations.
F. Multifamily Unit Requirements: Any attached residential arrangement of five (5) or more dwelling
units per lot will fall under the Commercial Business Category as defined by City of Denton Code
of Ordinances 24-2 Definitions (Commercial), which requires a solid waste and recycling storage
facility (container enclosure). See the Site Plan Criteria for Municipal Solid Waste & Recyclables
Storage & Enclosure Requirements in the City of Denton Standard Details.
Figure 3.3 Solid Waste Collection Vehicle Turn Radius Schematic
Design Criteria Manuals 27
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Section 4: Stormwater Design Criteria
4.1 Overview
The purpose of Section 4 - Stormwater Design Criteria of this DCM is to establish standard principles and
practices for the design and construction of storm drainage systems, to implement the policies set forth in
the DDC and the City of Denton Code of Ordinances, Subpart B, Chapter 30 (Denton Flood Prevention and
Protection Ordinance) within the City of Denton, Texas and its extraterritorial jurisdictions.
The following documents govern the design and construction of stormwater drainage systems:
A. City of Denton Code of Ordinances, Chapter 30, Flood Prevention and Protection;
B. DDC Subchapter 7.4 – Environmentally Sensitive Areas;
C. DDC Subchapter 7.5 – Drainage Standards;
D. iSWMTM Planning Technical Manual Document;
E. iSWMTM Water Quality Technical Manual Document;
F. iSWMTM Hydrology Technical Manual Document;
G. iswmTM Hydraulics Technical Manual Document;
H. iSWMTM Site Development Controls Technical Manual Document;
I. iSWMTM Construction Controls Technical Manual Document;
J. iSWMTM Construction Control Standard Details Technical Manual Document; and
K. iSWMTM Landscape Technical Manual Document.
The design factors, formulae, graphs, and procedures specified in this document are intended for use as
minimum engineering criteria for the design of drainage systems with regards to the quantity, rate of flow,
method of collection, storage, conveyance, detention, and disposal of storm water. Responsibility for
actual design remains with the design engineer. Users of this Manual should be knowledgeable and
experienced in the theory and application of drainage engineering.
The stormwater criteria contained in this Manual supersede any design criteria contained in the iSWMTM
Planning, Water Quality, Hydraulics, and Hydrology Technical Manual Documents. The stormwater design
criteria contained in this Manual do not supersede the criteria contained in the DDC or Chapter 30 of the
City of Denton Code of Ordinances. Any revisions to the DDC or Chapter 30 of the City of Denton Code of
Ordinances shall supersede the criteria in this Manual. In case of any conflict, the more stringent
requirement shall apply.
The requirements of this Manual shall apply to all public facilities and to private facilities when the
performance of such private facility has an effect on the public interest, health, or welfare.
4.1.0 Organization
Section 4 - Stormwater Design Criteria is categorized as follows:
A. Overview
B. Design Focus
Section 4: Stormwater Design Criteria
4.2 Design Focus
4.1.0 Organization
Design Criteria Manuals 28
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C. Design Storms
D. Hydrologic Methods
E. Acceptable Downstream Conditions for Open Channels and Floodplains
F. Stormwater System Design
G. Culverts
H. Bridges
I. Detention Facilities
J. Energy Dissipation
K. Floodplain
L. Drainage and Floodplain Easements
M. Water Quality
N. Stormwater Facility Maintenance Agreements
4.2 Design Focus
The design criteria for stormwater management primarily focus on:
4.2.1 Streambank Protection - Regulate discharge from the site to minimize downstream bank and
channel erosion;
4.2.2 Flood Mitigation and Conveyance - Control runoff within and from the site to minimize flood risk
to people and properties for the conveyance storm and the 1% chance storm; and
4.2.3 Water Quality - Reduce pollutants from stormwater by either infiltrating the water quality volume,
or removing 80% of total suspended solids (TSS) from any “Water Quality” storm event discharge.
4.3 Design Storms
Design is typically based on four (4) storm events, as detailed in Table 4.3-A.
Table 4.3-A: Design Storm Events
Storm Event Name Storm Event Description
“Water Quality” Criteria based on a volume of 1.5 inches of rainfall, not storm frequency
“Streambank Protection” 1-year, 24-hour storm event
“Conveyance” 25-year, 24-hour storm event
“Flood Mitigation” 100-year, 24-hour storm event
Notes:
[1] Throughout the manual, the storms will be referred to by their storm event names.
Drainage facilities shall be designed utilizing the “Flood Mitigation” storm event. Replacement or
modification of existing drainage facilities shall not reduce capacity , but such facility replacements or
modifications may be designed according to the requirements of the specific project and may utilize the
“Conveyance” storm as the design storm event, through an approved design deviation request.
Section 4: Stormwater Design Criteria
4.4 Hydrologic Methods
4.4.1 Types of Hydrologic Methods
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4.4 Hydrologic Methods
4.4.1 Types of Hydrologic Methods
The following empirical hydrologic methods support hydrologic site analysis for the design methods and
procedures included in this Manual:
A. Rational Method;
B. SCS Unit Hydrograph Method;
C. Modified Rational Method;
D. Snyder’s Unit Hydrograph Method; and
E. USGS & TxDOT Regression Equations
Table 4.4-A lists the hydrologic methods and the circumstances when they may be used in various analysis
and design applications. Table 4.4-B provides some additional constraints on the use of several methods.
Table 4.4-A: Applications of the Hydrologic Methods
Method Rational
Method SCS Method Modified
Rational
Snyder’s
Unit
Hydrograph
Method
USGS &
TxDOT
Equations
Streambank Protection Volume (SPV) ✓ ✓
Flood Mitigation Discharge (Qf) ✓ ✓ ✓
Storage Facilities ✓ ✓ ✓
Outlet Structures ✓ ✓
Gutter Flow and Inlets ✓ ✓
Storm Drain Pipes ✓ ✓ ✓
Culverts ✓ ✓ ✓ ✓
Bridges ✓ ✓
Small Ditches ✓ ✓ ✓
Open Channels ✓ ✓ ✓ ✓
Section 4: Stormwater Design Criteria
4.5 Acceptable Downstream Conditions for Open Channels and Floodplains
4.5.1 Rainfall Estimation
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Table 4.4-B: Constraints on Using Hydrologic Methods
Method Size Limitations 1 Used for Estimating
Rational 2 0 – 100 acres Peak flows and design of small site or subdivision storm sewer systems.
Modified Rational 3 0 – 200 acres Runoff volumes for storage design.
Unit Hydrograph (SCS) 4 Any Size Peak flows and hydrographs for all design applications.
Unit Hydrograph (Snyder’s) 5 1 acre and larger Peak flows and hydrographs for all design applications.
TxDOT Regression Equations 6 10 – 100 sq. mi. Peak flows for rural design applications.
USGS Regression Equations 6 3 – 40 sq. mi. Peak flows for urban design applications.
Notes:
[1] Size limitation refers to the drainage basin for the stormwater management facility (e.g., culvert, inlet).
[2] Acceptable for small, highly impervious drainage areas, such as parking lots and roadways draining into inlets and gutters.
[3] Used for conceptualizing; the engineer of record must use iSWM™ Hydrology Technical Manual Document when using this method.
[4] Refers to SCS routing methodology included in many readily-available programs (such as HEC-HMS or HEC-1) which utilize it.
[5] Refers to Snyder’s methodology included in many readily-available programs (such as HEC-HMS or HEC-1) which utilize it.
[6] The USGS and TxDOT equations should not be used when there are significant storage areas within the drainage basin or where other
drainage characteristics indicate general regression equations are not appropriate.
4.4.2 Rainfall Estimation
Rainfall intensities, provided in Table 5.3 of the iSWMTM Hydrology Technical Manual, are based on Atlas 14
and shall be used for all hydrologic analysis within Denton County.
4.5 Acceptable Downstream Conditions for Open Channels and
Floodplains
Storm water discharge from a development shall not cause adverse impacts to adjacent, upstream, or
downstream properties or facilities. The design of a storm drain facility must account for the offsite flows
that are routed through the development, flows generated by the development, and the impacts of the
development and the drainage system on downstream facilities.
4.5.1 Downstream Assessments
The downstream impacts of development must be carefully evaluated for the two (2) focus areas of
Streambank Protection and Flood Mitigation (See Section 4.2 of this Manual). The purpose of the
downstream assessment is to protect downstream properties from increased flooding and downstream
channels from increased erosion potential due to upstream development. The importance of the
downstream assessment is particularly evident for larger sites or developments that have the potential to
dramatically impact downstream areas. The cumulative effect of smaller sites, however, can be just as
dramatic and, as such, following the Focus Areas is just as important for the smaller sites as it is for the
larger sites.
A downstream assessment will be required for all developments which alter flow patterns or increase the
amount of impervious surface and do not limit the peak discharge to pre-development conditions at each
outfall from their site. The assessment shall extend from the outfall of a proposed development to a point
downstream where there is no calculated increase in WSEL (water surface elevation) or mean velocity within
the receiving stream or storm drainage system. The City shall be consulted to obtain records and maps
related to the National Flood Insurance Program (NFIP) and the availability of Flood Insurance Studies (FIS)
Section 4: Stormwater Design Criteria
4.5 Acceptable Downstream Conditions for Open Channels and Floodplains
4.5.2 Adverse Impacts
Design Criteria Manuals 31
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and Flood Insurance Rate Maps (FIRMs) which will be helpful in this assessment. The assessment must
include the following properties:
A. Hydrologic analysis of the pre- and post-development on-site conditions.
B. Drainage path that defines extent of the analysis.
C. Capacity analysis of all existing constraint points along the drainage path, such as existing
floodplain developments, underground storm drainage systems culverts, bridges, tributary
confluences, or channels.
D. Offsite undeveloped areas are considered as “full y developed” for both the pre- and post-
development analyses.
E. Evaluation of peak discharges and velocities for three (3) 24-hour storm events:
1. “Streambank protection” storm
2. “Conveyance” storm
3. “Flood Mitigation” storm
F. Separate analysis for each major outfall from the proposed development .
Once the analysis is complete, the designer must answer the following questions at each determined
junction downstream:
A. Are the post-development discharges greater than the pre-development discharges?
B. Are the post-development velocities greater than the pre-development velocities?
C. Are the post-development velocities greater than the velocities allowed for the receiving system?
D. Are there any increases in post-development flood heights above the pre-development flood
heights?
These questions shall be answered for each of the three (3) storm events. The answers to these questions
will determine the necessity, type, and size of non-structural and structural controls to be placed on-site or
downstream of the proposed development.
Section 2.0 of the iSWMTM Hydrology Technical Manual, as amended, gives additional guidance on
calculating the discharges and velocities, as well as determining the downstream extent of the assessment.
4.5.2 Adverse Impacts
Downstream Assessments shall evaluate the capacity of the downstream system within the Zone of Influence
(ZOI). If the downstream system has less than fully developed capacity, the study shall demonstrate the
development will produce no adverse impacts during the one (1), 25, and 100-year storm events. No adverse
impacts may include, but are not limited to:
A. No new or increased flooding of existing structures;
B. Zero increases (0.00’) in water surface elevations unless contained within the banks of an existing
channel including 1-ft. freeboard. Dry lane requirements set forth in Section 4.6.2 shall also be met;
C. Increasing channel velocity is prohibited where existing velocities are erosive. Any increase in
channel velocity in other areas must remain below the maximum allowable velocity as defined in
Table 4.6-E;
D. No increases in downstream discharges caused by the proposed development that, in combination
with off-site discharges, exceeds the existing capacity of the downstream storm drainage system;
E. The Downstream Assessment shall extend to a point downstream, known as the ZOI, where the
proposed development creates no adverse impacts. The ZOI will be defined by a detailed hydrologic
and hydraulic modeling analysis. The City’s Engineer may require analysis beyond the ZOI
Section 4: Stormwater Design Criteria
4.5 Acceptable Downstream Conditions for Open Channels and Floodplains
4.5.4 Stormwater Diversions
Design Criteria Manuals 32
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established by the Engineer of Record based on the criteria above and known flooding issues. ZOI
does not automatically end based the rule of thumb known as the "10% rule"; and
F. If the subject development is part of a larger development, the Downstream Assessment must
include the larger development, and the ZOI shall be determined based on the entire property.
4.5.3 Stormwater Diversions
Diversion of storm water away from the natural watercourse or existing discharge points will not be allowed,
except within the property boundaries controlled by the developer under the following conditions:
A. The storm water is returned to its natural flowing watercourse prior to leaving the developer's
property, or
B. A timing analysis of the existing and diverted hydrograph must be performed to confirm that the
peak flow rate has not been increased at the point that it reenters the watercourse, as a result of
the diversion. The City’s Engineer may require additional downstream analysis if there are known
downstream flooding or volume-sensitive areas.
4.5.4 Streambank Protection
There are two (2) options by which a developer can provide adequate streambank protection downstream
of a proposed development. The first step is to perform the required downstream assessment as described
earlier in Section 4.5.1 of this Manual. If it is determined that the proposed project does not exceed
acceptable downstream velocities or the downstream conditions are improved to adequately handle the
increased velocity, then no additional streambank protection is required. If the downstream assessment
shows that the velocities are within acceptable limits, then no streambank protection is required. Acceptable
limits for velocity control are provided in Table 4.6-D and Table 4.6-E of this Manual. If existing stream
velocities exceed the maximum allowable velocities, then no increase in velocities will be permitted. If the
downstream assessment shows an increase in velocity beyond the acceptable limits, then on-site or
downstream improvements are required for streambank protection, easements or right -of-entry
agreements will need to be obtained in accordance with Section 4.12 of this Manual, and one of the two
options below must be utilized for streambank protection.
Option 1: Reinforce/Stabilize Downstream Conditions
If the increased velocities are greater than the allowable velocity of the downstream receiving system, then
the developer must reinforce/stabilize the downstream conveyance system. The proposed modifications
must be designed so that the downstream system is protected from the post-development velocities. The
developer must provide supporting calculations and/or documentation that the downstream velocities do
not exceed the allowable range once the downstream modifications are installed.
Allowable bank protection methods include stone riprap, gabions, and bio -engineered methods. Sections
3.2 and 4.0 of the iSWMTM Hydraulics Technical Manual give design guidance for designing stone riprap for
open channels, culvert outfall protection, riprap aprons for erosion protection at outfalls, and riprap basins
for energy dissipation.
If the downstream receiving system is designated as an Environmentally Sensitive Area (ESA) this option
may not be a viable option. See Section 7.4 of the DDC for more information about the various types of
ESAs, permitted encroachments, and processes for assessing and modifying ESAs.
Option 2: Install Stormwater Controls to Maintain Existing Downstream Conditions
The developer must use on-site controls to keep downstream post-development discharges at or below
Section 4: Stormwater Design Criteria
4.5 Acceptable Downstream Conditions for Open Channels and Floodplains
4.5.5 Flood Mitigation
Design Criteria Manuals 33
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allowable velocity limits. The developer must provide supporting calculations and/or documentation that
the on-site controls will be designed such that downstream velocities for the three (3) storm events
(“Streambank Protection”, “Conveyance”, and “Flood Mitigation”) are within an allowable range once the
controls are installed.
4.5.5 Flood Mitigation
A. Introduction
Flood analysis is based on the “Flood Mitigation” storm event (see Table 4.3-A). The intent of the
flood mitigation criteria is to provide for public safety; minimize on-site and downstream flood
impacts from the “Flood Mitigation” storm event; maintain the boundaries of the mapped 100-year
floodplain; and protect the physical integrity of the on-site stormwater controls and the
downstream stormwater and flood mitigation facilities.
Flood mitigation must be provided for on-site conveyance systems, as well as downstream outfalls
as described in the following sections.
B. Flood Mitigation Design Options
There are three (3) options by which a developer may address downstream flood mitigation as
discussed below. When on-site or downstream modifications are required for downstream flood
mitigation, easements or right-of-entry agreements will need to be obtained.
The developer will provide all supporting calculations and/or documentation to show that the
existing downstream conveyance system has capacity (Qf) to safely pass the fully-developed flood
mitigation storm discharge.
Option 1: Provide or Document Adequate Downstream Conveyance Systems
When the downstream receiving system does not have adequate capacity, then the developer
shall provide modifications to the off-site, downstream conveyance system. If this option is
chosen, the proposed modifications must be designed to adequately convey the full build-out
stormwater peak discharges for the “Flood Mitigation” storm event. The modifications must also
extend to the point at which the discharge from the proposed development no longer has an
impact on the receiving stream or storm drainage system.
The developer must provide supporting calculations and/or documentation that the
downstream peak discharges are safely conveyed by the proposed system, without endangering
downstream properties, structures, bridges, roadways, or other facilities, and no increase in
water surface elevation.
Option 2: Install Stormwater Controls to Maintain Existing Downstream Conditions
When the downstream receiving system does not have adequate capacity, then the developer
shall provide stormwater controls to reduce downstream flood impacts. These controls include
on-site controls such as detention, regional controls, and, as a last resort, local flood protection
such as levees, floodwalls, floodproofing, etc.
The developer must provide supporting calculations and/or documentation for each existing
discharge point indicating that the controls will be designed and constructed so that there is no
increase in downstream peak discharges or water surface elevations due to development.
Option 3: In lieu of a Downstream Assessment, Maintain Existing On-Site Runoff Conditions
Lastly with Option 3, on-site controls shall be used to maintain the pre-development peak
discharges for each existing discharge point from the site. The developer must provide
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Introduction
Design Criteria Manuals 34
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supporting calculations and/or documentation that the on-site controls will be designed and
constructed to maintain on-site existing conditions.
It is important to note that Option 3 may not require a downstream assessment. It is a detention-
based approach to addressing downstream flood mitigation after the application of the
integrated site design practices. However, a downstream assessment may be required for sites
adjacent to or near streams in which delayed release of flows from detention facilities could
potentially increase the peak flow in the stream due to coincident peaks. This assessment of the
impact of coincident peaks is required for all sites with a contributing drainage area greater than
or equal to 10% of the stream drainage area at the subject discharge point.
4.6 Stormwater System Design
4.6.1 Introduction
Stormwater system design is an integral component of both site and overall stormwater management
design. Good drainage design must strive to maintain compatibility and minimize interference with existing
drainage patterns; control flooding of property, structures, and roadways for design flood events; and
minimize the potential environmental impacts of stormwater runoff.
Stormwater collection systems must be designed to provide adequate surface drainage while at the same
time meeting other stormwater management goals such as water quality, streambank protection, habitat
protection, and flood mitigation. Fully developed watershed conditions shall be used for determining runoff
for the “Flood Mitigation” storm event.
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
A. Introduction
This section is intended to provide criteria and guidance for the design of on-site flood mitigation
system components including:
1. Street and roadway gutters;
2. Stormwater inlets;
3. Storm drainpipe systems; and
4. Parking lot sheet flow.
B. Streets and ROW
1. Design Criteria
a. Flow spread limits for curbed streets are shown in Table 4.6-A below.
b. Inverted crown sections are permitted only in alleys.
c. Street crowns shall be reduced for approximately 100 feet on each side of the valley
gutters. No valley gutters will be permitted across collectors or arterials.
d. For non-curbed streets the “Flood Mitigation” storm event shall be contained within
paralleling roadside ditches, within the public ROW (Figure 4. 1 below).
e. Roadside ditches shall be designed to carry the “Flood Mitigation” runoff below the
roadway elevation.
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
Design Criteria Manuals 35
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f. Streets or alleys adjacent to an open channel shall have the edge of the pavement
designed with a minimum elevation of one (1) foot above the “Flood Mitigation”
elevation or as directed by the City’s Engineer.
g. Where additional hydraulic capacity is required on the street, the proposed street
gradient must be increased, or curb inlets and storm sewers installed to remove a
portion of the flow.
h. The maximum concentrated flow directed into the street (from a driveway or flume, etc.)
is three (3) cubic feet per second (cfs).
2. Flow Spread Limits
a. Inlets shall be spaced so that the spread of flow in the street for the “Flood Mitigation”
storm shall not exceed the guidelines listed below in Table 4.6-A, as measured from the
gutter or face of the curb:
Table 4.6-A: Flow Spread Limits
Street Classification Allowable Encroachment
Collectors one travel lane remains open
Arterials one travel lane in each direction remains open
Residential Streets curb depth
b. The allowable drainage flow across street intersections for the “Flood Mitigation” storm
event shall be as shown in Table 4.6-B as follows:
Table 4.6-B: Permissible Flow Across Street Intersections
Street Classification Cross-Flow
Arterial Street (divided and undivided) None
Non-Residential Collector Street None
Residential Street and Residential Collector Gutter Flow of 2 inches or less
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
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Figure 4.1 Water Spread Limits for Non-Curbed Roadways
3. Minimum Street or Alley Elevations
No lowering of the standard height of street crown shall be allowed for the purposes of
obtaining additional hydraulic capacity. Street crowns shall be in accordance with the City of
Denton Standard Details.
C. Drainage Related Minimum Elevations
1. For lots in the influence of a sag area and a positive overflow, the finished floor elevation
(FFE) will be at least one (1) foot above the sag area top of the curb, or one (1) foot above
the possible maximum pool elevation when the positive overflow is functioning, whichever
elevation is higher.
2. New and substantially improved structures within the floodplain or within 200 feet of the
floodplain or SFHA must have their finished floor elevated to the minimum building elevation
as defined in the City’s Chapter 30 Flood Prevention and Protection Ordinance.
3. In all other areas, the minimum FFE shall be a minimum of one (1) foot above the street curb,
edge of alley, or rear property line (at the midpoint of the lot), whichever is lower.
D. Storm Inlet Design
1. Permissible Types of Inlet
a. Drop Inlets (Y-inlet) – Drop inlets are sump inlets which are not located along the curb
line of a roadway.
b. Grate Inlets – The use of grate inlets is not allowed on public drainage systems unless
through an approved design deviation request. If allowed, the inlet opening shall be
designed twice as large as the calculated opening to compensate for clogging. Grate
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
Design Criteria Manuals 37
Published: July January 20264 Go to Table of Contents
inlets may be used on private systems.
c. Curb Inlets – Curb inlets may be located at roadway low points (sumps) or on grade at
such points as to meet the water spread limitations and cross-flow depth requirements.
Curb inlets may be one of the following:
i. Recessed curb inlet – Recessed curb inlets are curb inlets constructed such that the
front of the inlet is two (2) feet behind the normal face of curb and the depression
does not extend into the traffic lanes.
ii. Standard curb inlet – Standard curb inlets are curb inlets that are in line with the
roadway curb.
iii. Type 2 curb inlet – Type 2 curb inlets are standard curb inlets where the inlet box
is located underneath the outer roadway lane instead of behind the curb. They are
only to be utilized in situations where there is insufficient parkway area or an
encumbered parkway area for a standard curb inlet.
2. Design Criteria
a. Public curb inlet size shall be 10, 15, or 20 feet. Maximum length of inlet at any one (1)
curb location shall be 20 feet on each side of the street. Inlets will be placed only in
straight sections of curb and at least 10 5 feet from any curb return. Inlets required in
cul-de-sacs are the only exceptions to the straight curb section requirement. Curb inlets
are not allowed in intersection or curb returns.
b. Recessed inlets will be required on arterial and non-residential collector streets.
c. The maximum inlet opening shall be six (6) inches. Openings larger than six (6) inches
shall require approval through a design deviation request and shall contain a bar or
other form of restraint.
d. Inlets shall be located in the following locations:
i. At low points;
ii. Upstream of pavement crown transitions at intersections (or the developer may
identify flow patterns and depths to show these inlets are not needed); and
iii. Where street flow spread limits or permissible intersection depths are exceeded.
e. Where possible, inlets at intersections shall be located on the street with the lesser
classification or on alleys.
f. A bypass of no more than 510% of the inlet capacity will be allowed for the “Flood
Mitigation” storm event.
g. To prevent water flowing across the street for the “Flood Mitigation” storm event, water
flowing in gutters of arterials should be picked up prior to reaching super -elevated
sections.
h. In super-elevated sections of divided arterials, inlets placed against the center medians
shall have no gutter depressions. Interior gutter flow (flow along the median) shall be
intercepted at the point of superelevation transition to prevent street cross-flow.
i. At bridges with curbed approaches, water should be intercepted before flowing onto
the bridge to prevent icing during cold weather.
j. New inlets shall not be constructed within a sidewalk orf other pedestrian path.
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
Design Criteria Manuals 38
Published: July January 20264 Go to Table of Contents
k. The use of recessed inlets shall only be allowed where they do not adversely impact the
access or functionality of existing utility facilities.
l. Design and location of inlets shall take into consideration pedestrian and bicycle traffic.
m. The use of slotted drains is discouraged except in instances where there is no alternative.
Any use of slotted drains requires approval through a design deviation request. If used,
the manufacturer’s design guidelines should be followed.
n. Depressed inlets are recommended on continuous grades that exceed 1%, although
their use in traffic lanes should be avoided whenever possible.
o. A redundant, flanking inlet is required wherever a sag point or low point inlet is
identifiedidentified, and no positive overflow path is provided. The redundant inlet shall
have the same size as the sag or low point inlet but will not be considered in the
hydraulic capacity calculations. The redundant inlet shall have a maximum inlet
elevation of six (6) inches above the sag or low point inlet elevation to ensure ponding
does not overtop the curb.
3. Inlet Computations
a. Sump Inlets and Drop Inlets
Curb inlets and drop inlets in a sump or low point can be considered to function as a
rectangular broad-crested weir with a coefficient of discharge of 3.06. The capacity shall
be based on the following weir equation:
Q / L or Q / P = 3.06 H3/2 [Eqn. 4.1]
Where: Q = Capacity of curb opening inlet or capacity of drop inlet (cfs)
H = Head at the inlet (feet)
L = Length of curb opening inlet (feet); or
P = Length of portion of perimeter of inlet opening, through which
water enters the drop inlet (feet)
Inlets should be located such that the inlet openings do not become submerged. In
some cases where this is not possible and the inlet operates under completely
submerged conditions, the orifice equation [Eqn. 4.2] should be used to compute the
inlet capacity, rather than the weir formula [Eqn. 4.1]. The capacity of a completely
submerged inlet shall be based on the following orifice equation:
Q = 4.84 A H1/2 [Eqn. 4.2]
Where: A = Area of inlet opening
The curves shown in Figure 4.2 and Figure 4.3 provide for direct solution of the above
equations.
In order to facilitate the computations required in determining the various hydraulic
properties for curb inlets and drop inlets in sump conditions, Figure 4.4 Computation
Sheet has been prepared.
Column 1 Inlet number and designation.
Column 2 Total flow in cfs to inlet. For inlets other than the first inlet in a system,
flow is the sum of runoff from the contributing area plus carry-over
flow from inlet or inlets upstream.
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
Design Criteria Manuals 39
Published: July January 20264 Go to Table of Contents
Column 3 Assumed length of inlet opening or perimeter in feet.
Column 4 Total area of inlet opening based on assumed inlet opening length
and opening height.
Column 5 Discharge per unit foot of inlet opening. Column 2 divided by Column
3.
Column 6 Computed head at inlet for weir flow conditions based on Figures 4.2
or 4.3 or the following equation:
H = (q / 3)2/3 [Eqn. 4.3]
Column 7 Computed head at inlet for orifice flow conditions (submerged inlet)
based on Figures 4.2 or 4.3 or the following equation:
H = [(Q / A) / 4.82]2 [Eqn. 4.4]
Column 8 Maximum allowable head at sump inlet. This value is determined from
topographic conditions at the sump inlet site.
Column 9 Width of spread of water for curb inlets in sump.
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
Design Criteria Manuals 40
Published: July January 20264 Go to Table of Contents
Figure 4.2 Capacity of Grate Inlet in Sump
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
Design Criteria Manuals 41
Published: July January 20264 Go to Table of Contents
Figure 4.3 Capacity of Drop Inlets and Curb Inlets in Sumps
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
Design Criteria Manuals 42
Published: July January 20264 Go to Table of Contents
Figure 4.4 Computation Sheet for Curb Inlets and Drop Inlets in Sumps
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
Design Criteria Manuals 43
Published: July January 20264 Go to Table of Contents
b. Inlets on Grade
The capacity of a curb inlet on grade will be based on the following equation:
Q / Lo = 0.7 [1 / yo] [(H)5/2 - (a)5/2] [Eqn. 4.5]
Where: Q = Discharge into inlet (cfs)
Lo = Length of inlet opening (feet)
a = Gutter depression (feet)
yo = Depth of flow in approach gutter (feet)
H = a + yo
The curve shown in Figure 4.6 provides for the direct solution of the above equation
when the value of yo is known. The curve shown in Figure 4.7 provides for the
determination of the ratio of the intercepted flow by the inlet to the total flow in the
gutter.
In order to facilitate the computations required in determining the various hydraulic
properties for curb inlets on grade, Figure 4.5 shows Computation Sheet prepared.
Column 1 Inlet Type and number.
Column 2 Location of inlet by station number.
Column 3 Drainage Area designation of area entering between the previous pick
up point and the inlet being designed.
Column 4 Peak Discharge (Qp) from area of Column 3.
Column 5 Carry-over flow (q) which has been passed by the last preceding inlet
to the inlet under consideration.
Column 6 Total gutter flow (Qo) in cfs. For inlets other than the first inlet in the
system, total gutter flow is the sum of the runoff from the contributing
area plus carry-over flow from the inlet or inlets upstream. Column 4
plus Column 5.
Column 7 Reciprocal of the pavement cross slope for pavements with straight
crown slopes.
Column 8 Reciprocal of the pavement cross slope (Z) divided by the pavement
roughness coefficient (n).
Column 9 Slope of approach gutter (So) in feet per feet.
Column 10 Depth of gutter flow "yo" in approach gutter direct from Manning’s
equation for triangular gutters:
yo = 1.245 (Q 3/8)[n3/8/ S3/16] [1 / Z]3/8 [Eqn. 4.6]
Column 11 Spread of water (Sp) or width of ponding in the gutter measured from
the face of curb. Column 7 times Column 10.
Column 12 Width of street and height of parabolic crown.
Column 13 Slope of approach gutter (So) in feet per feet.
Column 14 Depth of gutter flow " yo " in approach gutter.
Column 15 Spread of water (Sp) or width of ponding in the gutter
measured from face of curb.
Column 16 Discharge (Q) in cfs which will be intercepted by an inlet one (1) foot
in length for a given depth of flow in the approach gutter (yo).
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
Design Criteria Manuals 44
Published: July January 20264 Go to Table of Contents
Determined from Figure 4.6 or from the solution of the following
equation:
Q / Lo = 0.7 [1 / yo] [(H)5/2 - (a)5/2] [Eqn. 4.7]
Column 17 Length of inlet (Lo) in feet which is necessary to intercept a given
discharge Qo. Column 6 divided by Column 16.
Column 18 Actual length (L) in feet of inlet which is to be provided.
Column 19 Ratio of the length of inlet provided (L), to the length of the inlet
required for 100% interception (Lo). Column 18 divided by Column 17.
Column 20 Percentage of discharge intercepted by the inlet in question
determined from Figure 4.7 using the values determined in Column 19
and Column 10 or Column 14.
Column 21 Discharge (Q) in cfs which the inlet in question actually intercepts.
Column 6 times Column 20.
Column 22 Carry-over flow (q) is the amount of water which passes any inlet, and
is the difference between the total flow (Qo) of Column 6 and the
intercepted flow (Q) of Column 21.
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
Design Criteria Manuals 45
Published: July January 20264 Go to Table of Contents
Figure 4.5 Computation Sheet for Curb Inlets On Grade
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
Design Criteria Manuals 46
Published: July January 20264 Go to Table of Contents
Figure 4.6 Capacity for Inlets On Grade
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
Design Criteria Manuals 47
Published: July January 20264 Go to Table of Contents
Figure 4.7 Ratio of Intercepted Flow to Total Flow for Inlet On Grade
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
Design Criteria Manuals 48
Published: July January 20264 Go to Table of Contents
E. Storm Drain Pipe Design
1. Design Frequency
Pipe Design: “Flood Mitigation” storm event.
2. Design Criteria
a. Storm drain systems capable of conveying the “Flood Mitigation” storm event are
required when water spread, intersection cross-flow, and lot-to-lot drainage flow limits
are exceeded, or when the minimum time of concentration shown in Table 1.5 of the
iSWM™ Hydrology Technical Manual Document are reached. Closed pipe systems are
required for discharges up to and including 300 cfs in public systems.
b. Pipe material in a public storm drain system or in public ROW shall be reinforced
concrete for all pipe sizes, or Polypropylene for sizes up to 60” inches, with appropriate
bedding and class type depending on cover.
c. Proposed storm drains may discharge into existing watercourses. See Section 1.2.10 of
the iSWM™ Hydraulics Technical Manual Document for guidance related to the Tailwater
elevation to be used for hydraulic grade line calculations.
d. The maximum hydraulic gradient shall not produce a velocity that exceeds 15 fps. Table
4.6-C shows the desirable velocities for most storm drainage design. Storm drains shall
be designed to have a minimum mean velocity flowing full at 2.5 fps.
Table 4.6-C: Desirable Velocity in Storm Drains
Description Max. Desirable Velocity (fps)
Culverts (All types) 15
Inlet laterals No Limit
Collectors (≤ 24 inches) 15
Mains (> 24 inches) 12
e. The minimum desirable physical slope shall be 0.5% or the slope that will produce a
velocity of 2.5 fps as required for the “Streambank Protection” storm event when the
culvert is flowing partially full, whichever is greater.
f. The potential hydraulic grade line elevation shall not exceed ground elevation or the
gutter flow line, whichever is lowest.
g. Access junction boxes are required along straight runs of closed conduits, with a
maximum spacing of 500 feet for all pipe and box sizes.
g.h. A minimum of 24 inches” of vertical separation shall be maintained between storm
sewer conduits and any other utility. If it is not possible to provide 24” inches of vertical
separation, the design must be approved through a dDesign dDeviation rRequest and
shall not provide separation less than 6 inches" and must provide a concrete cap
between the crossing utility line.
h.i. Junction Boxes shall also be located at:
i. any point where three (3) or more drainage conduits (laterals or trunk lines) come
together;
ii. any point where a trunk line size changes;
iii. grade changes;
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.3 Open Channels
Design Criteria Manuals 49
Published: July January 20264 Go to Table of Contents
iv. the upstream end of the storm drain system;
v. Bends greater than 45 degrees;
vi. Pipe junctions greater than 45 degrees; and
vii. At the connection point between public and private storm sewer pipes or boxes. If
this connection point is in the public ROW, pipe materials on the private system
must meet public storm drain system materials requirements. If the connection
point is on private property, then the public portion of the system must be
contained in an easement.
i.j. Inlets will not be allowed to serve as a junction box, except through an approved design
deviation request. Where inlets are permitted to serve as a junction box, the width of
the inlet, at a minimum, shall be doubled in size. Storm drain systems parallel to the
street will not be permitted to run directly through inlets.
j.k. Bends without junction boxes shall be limited to 45 degrees or less.
k. Pipe junctions without junction boxes shall be limited to 45 degrees or less.
l. The minimum storm drain pipe diameter shall be 18 inches.
m. Pipe diameters shall not decrease downstream.
n. Laterals shall be connected to trunk lines using a junction box or manufactured wye
connections. Cut-in or punch-in connections to trunk linespipes are prohibited.
o. All cut-in or punch-in connections to precast inlets, junction boxes, box culverts, etc. will
require a concrete collar to be poured around the connection.
p. Vertical or horizontal curves/deflections in the conduit will not be permitted.
F. Parking Lot Design
Parking lots shall be designed for the “Flood Mitigation” storm not to exceed top of curb with a
maximum depth at low points of one (1) foot. The “Flood Mitigation” storm shall be contained on-
site or within dedicated easements. The portion of the parking lot detaining water during the “Flood
Mitigation” storm may be considered as part of the detention calculation for the site.
4.6.3 Open Channels
A. Design Frequency
1. Open channels, including all natural or improved channels, swales, and ditches shall be
designed for the “Flood Mitigation” storm event.
B. Design Criteria
1. Depending on velocities (See Table 4.6-E), constructed or improved channels shall be
designed with either an earthen channel or a 10-ft. minimum concrete pilot channel section
and appropriate side slope protection up to the “Streambank Protection” storm event
elevation, as described in Section 4.3.
2. All channels with contributing drainage basins larger than one (1) square mile (sq. mi.) shall
remain in their natural condition.
3. Channels with a contributing drainage area of less than one (1) sq. mi. shall remain in their
natural condition if they are identified as being within an ESA by the current City of Denton
ESA map. Channels not identified as being within an ESA may be channelized, with the
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.3 Open Channels
Design Criteria Manuals 50
Published: July January 20264 Go to Table of Contents
channelization method being determined by analysis of the erosive velocities.
4. All improved channels shall be designed to carry the flood mitigation flow and shall have
one (1) foot of freeboard as illustrated in Figure 4.8. Freeboard requirements at bends in all
improved channels shall be the greater of the following:
a. One (1) foot; or
b. 10% of the flow depth
5. At a minimum, channels that require concrete lining shall be lined up to an elevation of the
water surface resulting from the “Flood Mitigation” storm event.
6. Concrete lining of a stream channel is adding fill material into Waters of the United States
(WOTUS) and must comply with Section 404 of the Clean Water Act, and all requirements
outlined in DDC Section 7.4. Provide either proof of mitigation or letter of permission from
the United States Army Corps of Engineers (USACE).
7. Unlined improved channels that contain bends may be required to be armored if maximum
permissible velocities are exceeded.
8. Unlined improved channels shall have side slopes no steeper than 4H:1V and concrete-lined
channels shall have side slopes no steeper than 2H:1V.
9. The minimum grade allowed on any channel, outfall channel, or ditch shall be three-tenths
(3/10) foot per 100 feet for concrete-lined channels and five-tenths (5/10) foot per 100 feet
for grass-lined channels.
10. Geotechnical investigations will be required for open channel designs to determine the type
of soils present and allowable velocities shown in Table 4.6-D and Table 4.6-E.
11. For vegetative channels, flow velocities within the channel shall not exceed the maximum
permissible velocities given in Table 4.6-D and Table 4.6-E.
12. An evaluation of streambank stabilization shall be included in the design of open channel
improvements for areas upstream and downstream of the proposed improvement. Where
indicated by the analysis, stabilization of the offsite bank areas shall be included in the
proposed design.
13. HEC-RAS, or similarly capable software approved by the City’s Engineer, shall be used to
confirm the water surface profiles in open channels.
14. The final design of artificial open channels shall be consistent with the velocity limitations for
the selected channel lining. Maximum velocity values for selected lining categories are
presented in Table 4.6-D below.
15. If relocation of a stream channel is unavoidable, fill material into WOTUS must comply with
Section 404 of the Clean Water Act, and all requirements outlined in DDC Section 7.4 .
Provide either proof of mitigation or letter of permission from the United States Army Corps
of Engineers (USACE).
The design of stable rock riprap lining depends on the intersection of the velocity (local boundary
shear) and the size and gradation of the riprap material. More information on calculating acceptable
riprap velocity limits is available in Section 3.2.7 of the iSWM™ Hydraulics Technical Manual
Document.
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.3 Open Channels
Design Criteria Manuals 51
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Table 4.6-D: Roughness Coefficients (Manning’s n) and
Allowable Velocities for Natural Channels
Channel Description Manning’s
n
Max. Permissible
Channel Velocity
(fps)
MINOR NATURAL STREAMS
Fairly regular section
1. Some grass weeds 0.030 3 to 6
2. Dense growth of weeds, depth of flow materially greater than weed height 0.035 3 to 6
3. Some weeds, light brush on banks 0.035 3 to 6
4. Some weeds, heavy brush on banks 0.050 3 to 6
5. Some weeds, dense willows on banks 0.060 3 to 6
- For trees within channels with branches submerged at high stage, increase values by 0.010
- Irregular section with pools, slight channel meander, increase above values by 0.010
Floodplain - Pasture
1. Short grass 0.030 3 to 6
2. Tall grass 0.035 3 to 6
Floodplain – Cultivated Areas
1. No crop 0.030 3 to 6
2. Mature row crops 0.035 3 to 6
3. Mature field crops 0.040 3 to 6
Floodplain – Uncleared
1. Heavy weeds scattered brush 0.050 3 to 6
2. Wooded 0.120 3 to 6
MAJOR NATURAL STREAMS
Roughness coefficient is usually less than for minor streams of similar description on
account of less effective resistance offered by irregular banks or vegetation on banks.
Values of ‘n’ for larger streams of mostly regular sections , with no boulders or brush
0.028 to
0.060 3 to 6
UNLINED VEGETATED CHANNELS
Clays (Bermuda Glass) 0.035 5 to 6
Sandy and Silty Soils (Bermuda Glass) 0.035 3 to 5
UNLINED NON-VEGETATED CHANNELS
Sandy Soils 0.030 1.5 to 2.5
Silts 0.030 0.7 to 1.5
Sandy Silts 0.030 2.5 to 3.0
Clays 0.030 3.0 to 5.0
Coarse Gravels 0.030 5.0 to 6.0
Shale 0.030 6.0 to 10.0
Rock 0.025 15
Notes:
[1] For natural channels with specific vegetation type, refer to Table 4.6-E for more detailed velocity control.
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.3 Open Channels
Design Criteria Manuals 52
Published: July January 20264 Go to Table of Contents
Table 4.6-E: Maximum Velocities for Vegetative Channel Linings
Vegetation Type Slope Range 1
(%)
Max. Velocity 2
(fps)
Bermuda Grass 0 – 5 6
Bahia - 4
Tall fescue grass mixtures 3 0 – 10 4
Kentucky bluegrass 0 – 5 6
Buffalo grass 4 5 – 10
> 10
5
4
Grass mixture 4 0 – 5
5 – 10
4
3
Sericea lespedeza, Weeping lovegrass, Alfalfa 0 – 5 3
Annuals 5 0 – 5 3
Sod - 4
Lapped Sod - 5
Notes:
[1] Do not use on slopes steeper than 10% except for side-slope in combination channel.
[2] Use velocities exceeding 5 fps only where good stands can be maintained.
[3] Mixtures of Tall Fescue, Bahia, and/or Bermuda.
[4] Buffalo Grass and Grass Mixture will be required over other vegetation types where the maximum velocity is not exceeded.
[5] Annuals – used on mild slopes or as temporary protection until permanent covers are established.
Source: Manual for Erosion and Sediment Control in Georgia, 1996.
Figure 4.8 Freeboard Requirements and Channel Section Illustrations
Section 4: Stormwater Design Criteria
4.7 Culverts
4.7.2 Design Frequency
Design Criteria Manuals 53
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C. Channel Drop Structures
1. Sloping channel drops are permitted and are required to have a maximum slope of 4H:1V.
Vertical channel drops are not permitted.
2. The flow velocities in the channel upstream and downstream of the drop structure need to
satisfy the permissible velocities allowed for channels (Table 4.6-D). The velocities shall be
checked for flows produced by the “Streambank Protection” and “Flood Mitigation” storm
events.
3. An apron shall be constructed immediately upstream of the chute or stilling basin to protect
against the increasing velocities and turbulence which result as the water approaches the
drop structure. The apron shall extend at least five (5) feet upstream of the point where flow
becomes supercritical. In no case shall the length of the upstream apron be less than 10 feet.
4. An apron shall be constructed immediately downstream of the chute or stilling basin to
protect against erosion due to the occurrence of the hydraulic jump. The apron shall extend
a minimum of 10 feet beyond the anticipated location of the jump.
5. The design of drop structures is based on the height of the drop, the normal depths upstream
and downstream of the drop structure, and discharge.
6. When used, channel drop structures shall be located near bridges or culverts, as directed by
the City’s Engineer.
7. The location of the hydraulic jump should be determined based on the upstream and
downstream flow depths, and channel slopes.
8. The length of the hydraulic jump should be calculated to determine the length of the
downstream apron required to prevent erosion.
4.7 Culverts
Culverts are cross drainage facilities that transport runoff under roadways or other improved areas.
4.7.1 Design Frequency
A. Culverts shall be designed for the “Flood Mitigation” storm.
B. The “Flood Mitigation” storm shall be routed through all culverts to ensure building structures (e.g.,
houses, commercial buildings) are not flooded and damage does not occur to a highway or adjacent
property for this design event.
4.7.2 Design Criteria
A. Design Considerations
1. Roadway type;
2. Tailwater or depth of flow;
3. Structures, and property subject to flooding;
4. Emergency access; and
5. Road replacement costs.
Section 4: Stormwater Design Criteria
4.7 Culverts
4.7.3 Driveway Culverts
Design Criteria Manuals 54
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B. Velocity Limitations
1. The maximum velocity shall be consistent with channel stability requirements at the culvert
outlet.
2. The maximum allowable velocity is 15 fps, but outlet protection shall be provided where
discharge velocities will cause erosion conditions.
3. To ensure self-cleaning during partial depth flow, a minimum velocity of 2.5 fps is required
for the “Streambank Protection” storm when the culvert is flowing partially full.
C. Headwater Limitations
1. The allowable headwater is the depth of water that can be ponded at the upstream end of
the culvert during the “Flood Mitigation” storm event. The allowable headwater will be limited
by both of the following constraints or conditions:
a. The headwater must not damage upstream property.
b. The culvert headwater plus 12 inches of freeboard shall not exceed (i) top of curb or (ii)
pavement for the low point of the road over the culvert, whichever is lower.
D. Tailwater Considerations
1. If the culvert outlet is operating with a free outfall, the critical depth and equivalent hydraulic
grade line shall be determined.
2. For culverts that discharge to an open channel, the stage-discharge curve for the channel
must be determined. See Section 2.1.4 of the iSWM™ Hydraulics Technical Manual on
methods to determine a stage-discharge curve.
3. If an upstream culvert outlet is located near a downstream culvert inlet, the headwater
elevation of the downstream culvert will establish the design tailwater depth for the upstream
culvert.
4. If the culvert discharges to a lake, pond, or other major water body, the expected “Flood
Mitigation” storm event of the water body will establish the culvert tailwater.
E. Other Criteria
1. Culvert skews shall not exceed 30 degrees, as measured from a line perpendicular to the
roadway centerline, without approval.
2. Erosion, sediment control, and velocity dissipation shall be designed in accordance with
Section 4.0 of the iSWM™ Hydraulics Technical Manual Document.
3. Where applicable, culverts must comply with DDC Section 7.4 regarding Environmentally
Sensitive Areas.
4.7.3 Driveway Culverts
Driveway culverts are only permitted in non-curbed roadway sections. All driveway culvert construction shall
be inspected by the City during construction. All driveway culverts shall meet the following requirements:
A. All new driveway culverts must be designed to convey flows from a “Flood Mitigation” storm.
Replacement driveway culverts shall be designed to convey the maximum reasonable discharge
based on the existing ditch dimensions adjacent to the culvert.
B. Culverts shall have a minimum pipe diameter of 18 inches.
Section 4: Stormwater Design Criteria
4.8 Bridges
4.8.2 Design Frequency
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C. Acceptable culvert material shall be Reinforced Concrete Pipe (RCP) with a diameter of 18 to 42
inches. The RCP must be designated Class III at a minimum.
D. Box culverts shall have a minimum height of 24 inches. Culverts under City streets used for
entrances to a subdivision shall be made of approved classes of reinforced concrete pipe or box.
E. The top of pipe elevation must be below the adjacent roadway edge of pavement elevation.
F. Pipe culverts shall utilize a safety end treatment conforming to the most current version of the
TxDOT standard detail Safety End Treatment Plan – Parallel Drainage (SETP-PD) with the slope of
the riprap being 6H:1V.
G. A driveway approach may utilize a low-water crossing in lieu of a driveway culvert, if all of the
following conditions are met:
1. The lowest elevation of the proposed crossing can be no more than eight (8) inches below
the road edge elevation.
2. The proposed low-water crossing cannot create a ponding effect on the upstream ditch (i.e.,
ditch flow line must be equal to or higher than the crossing).
3. Minimum cross slope for the crossing of 1.5%.
4. Low-water crossing shall be constructed of concrete adhering to the City of Denton Standard
Details.
5. Toe walls on each side of the crossing shall be extended at least 15 inches below grade to
prevent undercutting.
H. Culvert Slope requirements:
1. Culvert slope must provide positive drainage.
2. Culvert slope shall be set as shown on the approved subdivision construction plans.
3. Minimum slope shall be 0.3%.
I. Ditch Slope Requirements
1. The ditch shall be graded upstream and downstream as far as necessary to provide positive
drainage with no areas of standing water.
2. Minimum earthen slope is 0.5%.
3. Minimum concrete slope is 0.3% for 2-ft. concrete pilot channels, if 0.5% earthen slope is
unobtainable.
4.8 Bridges
4.8.1 Design Frequency
A. “Flood Mitigation” storm must be used for all bridges.
4.8.2 Design Criteria
A. A freeboard of two (2) feet shall be maintained between the computed design water surface and
the low chord of all bridges.
Section 4: Stormwater Design Criteria
4.9 Detention Facilities
4.9.2 Other Criteria
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B. Design guidance is provided in Section 3.4 of the iSWM™ Hydraulics Technical Manual Document.
4.8.3 Other Criteria
A. Where applicable, bridges must comply with DDC Section 7.4 regarding Environmentally Sensitive
Areas.
4.9 Detention Facilities
4.9.1 Design Requirements
A. Detention facilities shall be designed for the four storms (“Water Quality”, “Streambank Protection”,
“Conveyance”, and “Flood Mitigation” ) for the critical storm duration that results in the maximum
(or near maximum) peak flow.
B. Dry detention basins must be sized to temporarily store the volume of runoff required to provide
flood protection up to the “Flood Mitigation” storm.
C. Routing calculations must be used to demonstrate that the storage volume and outlet structure
configuration comply with Section 4.5.5 of this Manual.
D. A calculation summary shall be provided on construction plans as shown in the computation sheet
in Figure 4.9 or its equivalent. Stage-storage-discharge values shall be tabulated and flow
calculations for discharge structures shall be shown on the construction plans. Detention design
shall follow iSWM™ guidelines. It is the responsibility of the Engineer of Record to use appropriate
methodologies presented in iSWM™ based on specific basin characteristics. Detailed calculations
and a design narrative shall be provided for review in a supplemental report that is referenced on
the construction plans. In general, the narrative shall provide basic design information, such as the
hydrologic method applied, design assumptions, pre- and post-development site conditions,
downstream constraints, environmental considerations, and design software version used, if
applicable.
E. Storage and dam safety design may be subject to the requirements of the Texas Dam Safety
Program based on the volume, dam height, and level of hazard. Earthen embankments six (6) feet
in height or greater shall be designed per the TCEQ guidelines for dam safety (See Texas
Administrative Code, Title 30, Part 1, Chapter 299 Dams and Reservoirs for current dam safety
criteria).
F. An Operation and Maintenance Manual must be submitted with the civil engineering plans for all
private detention basins. Private detention basins shall be inspected by Public Works Inspection to
ensure compliance with the design standards required by Section 7.5.3.F. of the DDC. Inspection
fees will apply.
4.9.2 Design Criteria for Above Grade Detention Facilities
A. Grading Standards for Above Grade Detention Facilities:
1. Vegetated channel slopes shall not exceed 4H:1V slope. Concrete-lined embankment slopes
shall not exceed 2H:1V slope. Vertical walls may be allowed but must be structurally designed
to account for inundation of the base and drawdown upon pond draining and must have a
6-ft. high security fence at the top.
Section 4: Stormwater Design Criteria
4.9 Detention Facilities
4.9.2 Design Criteria for Above Grade Detention Facilities
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2. The side slope for any excavated detention basin, which is not in rock, shall not exceed a
4H:1V slope.
3. Bottom slopes of detention facilities should not be less than 1%.
4. Armored slopes shall be no steeper than 2H:1V.
5. The embankment crown width shall be determined based on a geotechnical investigation of
the detention facility site. The minimum width of the embankment crown shall be 12 feet.
6. Earthen embankments used to impound detention water must have a non-permeable core
and shall be based on a geotechnical investigation of the site. The geotechnical investigation
shall be performed by a Professional Engineer (PE), licensed by the State of Texas, and shall
include at a minimum the type of material on-site (or other material to be used in the
embankment), moisture content, liquid limit, plasticity index, and required compaction.
7. A Concrete pilot channel with a minimum width of 10 feet, and a minimum slope of 0.5%
shall be constructed at the bottom of the detention pond. Privately maintained ponds shall
have a concrete pilot channel with a minimum width of six (6) feet.
8. Private Detention Basins shall be designed with 10-ft. wide unobstructed maintenance
access around the entire perimeter of the pond.
9. Public Detention Basins shall be designed with 20-ft. wide unobstructed maintenance access
around the entire perimeter of the pond.
10. Where deemed necessary by the City’s Engineer, security fencing with a minimum height of
six (6) feet shall encompass the detention storage area if the velocity, depth, or slopes create
a potentially dangerous condition. The fence shall be designed to allow access for
maintenance and so as not to restrict stormwater flow into or out of the detention basin. A
maintenance equipment access ramp shall be provided for all detention facilities. The slope
of the ramp shall not exceed 6H:1V and the minimum width shall be 12 feet.
B. Emergency Spillway, Overflow Path, and Freeboard:
1. A freeboard of one (1) foot will be required between the “Flood Mitigation” storm water
surface elevation and top of bank.
2. An emergency spillway shall be provided at the flood mitigation maximum storage elevation
with sufficient capacity to convey “Flood Mitigation” storm inflow rates with six (6) inches of
freeboard. This is the peak of the inflow hydrograph coming into the pond and must not
account for attenuation effects of the pond. Spillway requirements must also meet all
appropriate State and Federal criteria.
3. An emergency overflow path, free of structures or obstructions, must be provided to convey
the spillway design discharge to a downstream ROW or drainageway with adequate capacity
for the discharge. No impediments to flow are allowed within the emergency overflow path
(E.g., fences, trees, parking areas, or buildings). If a fence around a detention facility is needed
to restrict access, the bottom of the fence must be elevated to provide a minimum of one
foot of freeboard above the emergency overflow WSEL where the fence crosses the spillway.
Nevertheless, fences across spillways should be avoided whenever possible. Even if the fence
is elevated to the freeboard elevation, there is still the potential for the fence to catch debris
floating on the water surface.
4. An emergency spillway must be constructed of concrete.
Section 4: Stormwater Design Criteria
4.9 Detention Facilities
4.9.3 Design Criteria for Underground Detention Facilities
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5. Design calculations shall be provided for all spillways and outlet structures.
C. Landscaping Requirements:
1. All detention basins shall be designed with plantings that minimize erosion based on
expected inundation frequencies. Design guidance is provided in the iSWM™ Landscape
Technical Manual Document.
D. Multiple Use Guidance
Limited recreational equipment (such as picnic tables or playground equipment) and trees may be
permitted in private detention facilities with the following restrictions:
1. User access must be provided at a maximum 10% slope in at least two (2) locations, or one
(1) location that comprises not less than 20% of the perimeter of the facility.
2. No recreational equipment is permitted in any portion of the facility that lies more than 18
inches below the flood mitigation water surface elevation level of the facility.
3. Recreational structures including, but not limited to, picnic tables and playground
equipment, must be rust-resistant and anchored to the ground.
4. Mulch, wood chips, gravel, or rubberized pellets are not permitted within a detention facility
due to the likelihood of their floating into the outlet structure.
5. Trees, shrubs, and other woody vegetation will not be permitted in the embankment of any
detention facility or in the maintenance access area around such a facility.
6. A maximum of one (1) isolated tree per 5,600 sq. ft. may be permitted in the recreational
area of the pond. A trash rack must be used to prevent clogging of the outlet structure. No
bark mulch may be used around trees.
E. Retaining Walls
1. Any freestanding retaining wall used to detain water must be designed by a structural
engineer to withstand the expected hydraulic forces when the detention area is filled to
capacity. These walls must be constructed using reinforced concrete.
2. Any inlet or pipe connections to retaining walls must be designed with a reinforced concrete
headwall. The height of this headwall shall match the height of the adjacent retaining wall.
The most recent TxDOT details for concrete headwalls shall be used to determine other
headwall dimensions and reinforced schedule.
4.9.3 Design Criteria for Underground Detention Facilities
Underground detention is highly discouraged because of the potential for deferred maintenance, the
difficult and potentially hazardous nature of access for maintenance, and issues related to anaerobic
conditions and pollutant mobility from devices that retain water between events. In any instance where
underground detention is contemplated, thorough consideration must be given to the concerns described
above to ensure ongoing inspection, maintenance, and functionality. Care should be taken to address
material selection for underground detention due to the potential for adverse soil conditions to inhibit the
system from functioning properly. A geotechnical engineer shall be consulted to ensure soil and other
conditions are appropriate for the selected detention material.
A. Underground detention facilities shall be designed with reinforced concrete and have a minimum
pipe diameter of 30 inches to allow for safe access and maintenance of the facility.
Section 4: Stormwater Design Criteria
4.9 Detention Facilities
4.9.4 Design Criteria for Parking Lot Detention
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B. If an underground vault has multiple chambers, access openings with a maximum spacing of 500
feet must be provided for each chamber.
C. Underground facilities must be located to enable safe access for maintenance and minimize
disruption of aboveground uses during maintenance. Access openings shall not be placed in areas
that are routinely used for parking.
D. Easements must be provided for all underground detention facilities. If underground detention
facilities are bound by private property, the easements must include an additional four (4) feet from
the perimeter of the facilities.
E. Underground detention and water quality facilities are prohibited underneath buildings, walls, or
other structures.
F. Every SWFMA involving underground detention and water quality facilities must include inspection
and maintenance requirements to be performed quarterly and following any rainfall event of 0.5
inches or more. The inspection and maintenance frequency may be reduced after five (5) years of
operation, if the owner demonstrates that a lesser frequency is appropriate.
G. A surface emergency overflow path, free of obstructions, must be provided for all underground
detention facilities. The emergency overflow path must have sufficient capacity to convey the “Flood
Mitigation” storm inflow rates to the underground detention facility. This is the peak of the inflow
hydrograph coming into the underground detention facility, and must not account for any
attenuation effects from the facility. The criteria for emergency overflow paths for surface detention
facilities denoted in Section 4.9.2 above also apply to underground detention facilities.
H. Outlets from underground detention must consist of a pipe that can convey 120% of the 100 -year
outflow, with a minimum diameter of 12 inches. The invert of the outlet pipe must be at the lowest
point in the detention facility to ensure that it fully drains.
I. Underground detention facilities shall be sloped to drain at a minimum floor slope of one (1) %
percent.
4.9.4 Design Criteria for Parking Lot Detention
Parking lot detention may be allowed if the following minimum criteria are met:
A. Use of parking lot surface area as detention is permitted, but only up to the lowest curb elevation
of the parking lot.
B. The maximum ponding depth for the 100-year storm must be no more than 12 inches at the
deepest point.
C. The outlet must be designed to minimize modifications that affect detention functions. The
applicant must evaluate potential future resurfacing activities for impacts to detention volumes and
release rates.
D. Ponding water in frequently used portions of parking lots must be avoided. At least two signs are
required for all parking lot detention areas. The signs must have a minimum area of 1.5 sq.uare feet.
and contain the following message:
WARNING
This area is a detention basin and is subject to periodic
flooding to a depth of (provide design depth).
Section 4: Stormwater Design Criteria
4.9 Detention Facilities
4.9.6 Design Criteria for Pumped Detention
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Sign materials, geometry, and location must be submitted to Development Facilitation and
approved by the City’s Engineer.
4.9.5 Design Criteria for Pumped Detention
A. A detention facility may not rely on a pump or other mechanical equipment to drain water during
a design storm.
4.9.6 Outlet Structures for Detention Facilities
A. Design Frequency
1. “Water Quality” storm
2. “Streambank Protection” storm
3. “Conveyance” storm
4. “Flood Mitigation” storm
B. Design Criteria
1. Outlet structures shall be designed in accordance with sSection 2.2 of the iSWMTM Hydraulics
Technical Manual. For water quality, refer to Section 2.2.3 for design of extended detention
outlets.
2. The required storage volumes for “Water Quality”, “Streambank Protection”, “Conveyance”,
and “Flood Mitigation” storm events must be estimated.
3. If a detention facility includes extended detention, refer to Section 2.2.3 of the iSWMTM
Hydraulics Technical Manual for design requirements.
4. All outlet orifices must be adequately protected from clogging and designed to ensure that
people and large animals are kept out of confined outlet areas. Refer to Sections 2.2.5-
Extended Detention Outlet Protection and 2.2.6-Trash Racks and Safety Grates of the iSWMTM
Hydraulics Technical Manual section 2.2.5 Extended Detention Outlet Protection and section
2.2.6 Trash Racks and Safety Grates for design guidance.
5. Any top orifice on an outlet riser must be designed with a grate to prevent fall injuries.
2.6. Outlet velocities shall be within the maximum allowable range based on channel material, as
shown in Table 4.6-D and Table 4.6-E.
3.7. Outlet protection and energy dissipation facilities must be designed to avoid erosion
problems downstream from outlet devices and emergency spillway(s).
4.8. Buoyancy calculations must be performed for the outlet structure and footing to ensure the
outlet structure will not float. Flotation will occur when the weight of the structure is less
than or equal to the buoyant force exerted by the water.
5.9. Any outflow structure that conveys water through an embankment in a conduit shall be
reinforced concrete designed to support the external loads. The conduit shall be able to
withstand the internal hydraulic pressure without leakage under full external load or
settlement and must convey water at the design velocity without damage to the interior
surface of the conduit.
Section 4: Stormwater Design Criteria
4.9 Detention Facilities
4.9.6 Outlet Structures for Detention Facilities
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6. The minimum pipe size and box size shall meet the requirements as shown below in Table
4.9-A. These minimum sizes apply even when used in conjunction with weirs or other flow
control devices and must be accessible for maintenance.
Table 4.9-A: Outlet Pipe and Box Size
Discharge Pipe Length Minimum Pipe Size Minimum Box Size
100 feet or less 18 inches 2-ft. x 2-ft.
Greater than 100 feet 36 inches 3-ft. x 3-ft.
7.10. The minimum opening of an inlet shall be six (6) inches in diameter or a 6-in. by 6-in. square.
Smaller inlet openings may be used with a junction box and properly sized outlet structure.
8. Inlet openings less than one (1) sq. ft. in area shall be designed with trash racks to protect
from clogging. The face of the trash rack should extend a minimum of six (6) inches from the
face of the inlet opening.
9.1. Any top orifice on an outlet riser must be designed with a grate to prevent fall injuries.
10.11. A concrete headwall and wingwalls shall be constructed at the outlet pipe opening.
Orientation of the wingwalls will be governed by site specific conditions. Headwalls and
wingwalls shall be designed to TxDOT standards.
11. Design guidance is in Section 2.2 of the iSWM™ Hydraulics Technical Manual.
Section 4: Stormwater Design Criteria
4.9 Detention Facilities
4.9.6 Outlet Structures for Detention Facilities
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Figure 4.9 Computation Sheet for Detention Pond Design
Section 4: Stormwater Design Criteria
4.10 Energy Dissipation
4.11.1 Design Frequency
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4.10 Energy Dissipation
All drainage system outlets, whether for closed conduits, culverts, bridges, open channels, or storage
facilities, shall provide energy dissipation when necessary to protect the receiving drainage element from
erosion.
4.10.1 Design Frequency
A. “Flood Mitigation” storm
4.10.2 Design Criteria
A. Erosion problems at culvert, pipe and engineered channel outlets are common. Determination of
the flow conditions, scour potential, and channel erosion resistance shall be standard procedure for
all designs.
B. Energy dissipaters shall be employed whenever the velocity of flows leaving a stormwater
management facility exceeds the erosion velocity of the downstream area channel system.
C. Energy dissipater designs will vary based on discharge specifics and tailwater conditions.
D. Outlet structures shall provide uniform redistribution or spreading of the flow without excessive
separation and turbulence.
4.10.3 Recommended Energy Dissipater for outlet protection
A. Concrete or grouted rock riprap apron
B. Riprap outlet basins
C. Baffled outlets
D. Grade Control Structures
Design guidance is provided in Section 4.0 of the iSWMTM Hydraulics Technical Manual.
4.11 Floodplain
4.11.1 Floodplain Development Criteria
A. Floodplain alterations shall be allowed only if all the following criteria are met:
1. An approved Floodplain Development Permit must be issued by the City before any
development is done within the floodplain.
2. Flood studies shall include flows generated for existing conditions and fully-developed
conditions for the 10, 50, 100, and 500-year storm events.
3. Alterations shall not increase the 100-year fully-developed water surface elevation on other
properties.
4. Alterations to the regulatory Floodway shall not increase the 100-year fully-developed water
surface elevation at any point.
5. Alterations shall be in compliance with Federal Emergency Management Agency (FEMA)
guidelines.
Section 4: Stormwater Design Criteria
4.11 Floodplain
4.11.1 Floodplain Development Criteria
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6. Alterations of the floodplain shall meet the requirements of Section 4.5 of this Manual.
7. Alterations shall result in no loss of valley storage for a Major Creek, as defined by the DDC,
and a 15% maximum loss of valley storage for any other tributary for any reach, except at
bridge and culvert crossings where it can be proven that there are no detrimental effects
upstream or downstream.
8. Alteration of floodplain areas shall not cause any additional expense, including maintenance,
related to any current or projected public improvements.
9. The floodplain shall be altered only to the extent permitted by equal conveyance on both
sides of the natural channel, as defined by the USACE in a HEC-RAS analysis. The right of
equal conveyance applies to all owners and uses, including greenbelt, park areas, and
recreational areas. Owners may relinquish their right to equal conveyance by providing a
written agreement to the City’s Engineer.
10. A grading permit and/or construction plan approval shall be required to perform any grading
activities on site.
11. The toe of any fill shall parallel the natural direction of the flow.
12. Floodplain alterations shall incorporate and consider other City planning documents and
ordinances such as the Tree Preservation Ordinance (Section 7.7.4 – DDC), , the Subdivision
Ordinance (Subchapter 8 – DDC), and the Floodplain Prevention and Protection Ordinance
(Chapter 30 – City of Denton, Code of Ordinances).
13. Unless a pre-existing model is in place, USACE’s HEC-HMS and HEC-RAS shall be used. A
request to use another type of hydrologic or hydraulic model must be submitted for approval
through a design deviation request. The Modified Puls method shall be used for flood
routing information to ensure that the cumulative effects of the reduction in floodplain
storage of floodwater will not cause downstream or upstream increases in water surface
elevations and erosive velocities. If the Modified Puls method is not feasible, a request to use
another type of flood routing method must be submitted for approval through a design
deviation request.
B. The engineer of record is responsible for providing documentation of the relevant USACE approved
permits prior to beginning modification of the floodplain and prior to causing any impacts to
WOTUS. If applicable, the engineer of record is also responsible for providing a signed and sealed
statement detailing why such permits are unnecessary.
C. Verification of Floodplain Alterations:
1. The owner and/or developer shall furnish, at their expense, to Development Services
sufficient engineering information to confirm that the minimum FFEs proposed meet the
requirements of the Flood Prevention Ordinance.
2. Construction plans will not be released for construction within areas subject to a Conditional
Letter of Map Revision (CLOMR) or amendment until such plans are accepted by
Development Services and FEMA.
3. Letters of Map Revision (LOMR) applications shall be submitted to Development Services (i)
no later than 60-days from the City’s final acceptance of the construction and (ii) prior to
submittal to FEMA.
4. All submittals to FEMA shall be submitted to Development Services prior to submittal to
Section 4: Stormwater Design Criteria
4.11 Floodplain
4.11.1 Floodplain Development Criteria
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FEMA. A copy of all responses to FEMA comments shall be submitted to the City.
D. Development within the floodplain which does not result in any change to the topography, the
amount or location of impervious area, or any change in the characteristics of the floodplain cross -
section, such as underground utility construction, may not require a flood study, CLOMR, LOMR, or
DSA unless requested by the City.
The following decision charts are intended to consolidate the floodplain development criteria in the City of
Denton. They reference information found in the DDC Subchapters 7.4 and 7.5, the Code of the City of
Denton, Texas, Chapter 30, and this Manual. They are not an exhaustive list of criteria and are only to be
used as guidance as to the information provided in the above-referenced documents. Criteria in those
documents supersedes the decision charts.
Figure 4.10 Flood Study Decision Chart
Section 4: Stormwater Design Criteria
4.11 Floodplain
4.11.1 Floodplain Development Criteria
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Figure 4.11 Summarized Floodplain Development Procedure
Section 4: Stormwater Design Criteria
4.11 Floodplain
4.11.2 Procedures for Floodplain Alteration
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4.11.2 Procedures for Floodplain Alteration
Floodplain development is permitted when it complies with all requirements of the DDC, Flood Prevention
Ordinance, and this Manual. The following are the engineering criteria for such requests.
Developments which impact designated FEMA flood plains in the City (Zones AE, A, and X shaded) shall
submit minimum data required by FEMA, indicated on the City’s CLOMR submittal checklist, and/or
indicated in this Manual to FEMA for conditional approval. The Conditional Letter of Map Revision (CLOMR)
shall be submitted to the City prior to approval of any Zoning Compliance Plan. Approval of CLOMR from
FEMA will be required prior to acceptance of Civil Engineering Plans.
A. A written description of the scope of the proposed project and the methodology used to analyze
the project’s effects.
B. Hydraulic backwater models for 10, 50, 100, and 500-year floods for the following:
1. Duplicate of the effective FIS model. The model must include:
a. Existing conditions (effective FIS model including cross-sections through the project
site. All cross-sections should reflect conditions prior to construction of the project); and
b. Proposed conditions (existing conditions model reflecting the proposed project).
C. Floodway hydraulic backwater models of the following:
1. Duplicate effective;
2. Existing condition; and
3. Proposed conditions.
D. In all the above hydraulic models, the following rules will apply:
1. The hydraulic parameters, such as bridge loss coefficients, “n” values, etc., used in the
effective FIS models will only be changed where obvious errors or changes have taken place
and must be documented;
2. The computed water surface elevation profiles must converge with the existing profiles; and
3. Information should be shown on a map of suitable scale and topographic definition to
provide reasonable accuracy.
E. A copy of the FIRM with the project area indicated.
F. Topographic mapping of the entire area covered by the proposed condition model, indicating the
locations of all cross-sections used in the hydraulic model and delineating the proposed 100-year
flood plain boundary.
G. Topographic mapping of the entire area covered by the proposed conditions model, indicating the
locations of all cross-sections used in the hydraulic model and delineating:
1. The proposed 100-year and 500-year floodplain boundaries; and
2. The proposed floodway boundary.
H. Projects must comply with the requirements of 44 C.F.R. § 60.3(d)(2).
I. Upon completion of the proposed project, “as-built” and final LOMR plans certified by a
Professional EngineerPE licensed by the State of Texas shall be submitted to the City for review and
subsequent transmittal to FEMA. FEMA requires that individual legal notices be sent to all affected
property owners when development (cut or fill) occurs in the regulatory floodway that would cause
Section 4: Stormwater Design Criteria
4.11 Floodplain
4.11.4 Fully Developed Water Surface Elevation Calculations
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any rise in the 100-year FIS water surface elevation. Public notice in the official community
newspaper is required for proposed modifications to the regulatory floodway.
J. All items should be labeled for easy cross-referencing to the hydraulic model and summary data.
K. FEMA may have questions regarding the project. The engineer of record must address all of FEMA’s
comments. It is not anticipated, but if revisions to the development are required by FEMA, the
developer is responsible for making the changes.
4.11.3 Fully Developed Water Surface Elevation Calculations
A. The following hydraulic data should be submitted to the City, preferably using the USACE HEC-RAS
program to compute the channel’s water surface elevation. The data should be submitted
electronically as part of the CLOMR, LOMR, or flood study submittal.
1. Duplicate of the effective City fully developed backwater model or as developed by
developer or property owner and approved by the City.
2. Modified existing condition backwater model – this model should include pre-development
cross-sections through the project site obtained from field surveys or updated topographic
information.
3. Proposed condition reflecting the development’s impact on the flood plain area.
4. Water surface elevation and velocity summary tables tabulating the results of the above
analysis.
5. Topographic map at a suitable scale with cross-sections that delineates the existing and
proposed 1% chance (100-year) fully developed flood plain and shows the area being
developed.
6. Analysis of the existing and proposed valley storage conditions of the area.
7. Documentation from the USACE determining if a 404 permit is required for the project.
4.11.4 Floodplain Alteration Guidelines
A. Side Slopes
1. To ensure maximum accessibility to the floodplain for maintenance and other purposes, and
to lessen the probability of slope erosion during periods of high water, maximum slopes of
filled area shall usually not exceed 4H:1V. Grass cover is required for all cut and fill slopes
unless other armoring is required. Concrete riprap or an approved equal erosion protection
measure is required on slopes steeper than 4H:1V. Vertical walls, terracing and other slope
treatments will be considered only as:
a. Part of a landscaping plan submission, and
b. If no unbalancing of stream flow results.
B. Vegetation/Landscaping
1. Engineering plan submission shall include plans for:
a. Erosion control of cut and fill slopes;
b. Restoration of excavated areas; and
c. Tree protection in and below fill areas.
Section 4: Stormwater Design Criteria
4.12 Drainage and Floodplain Easements
4.12.2 General
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2. Landscaping should incorporate natural materials (earth, stone, and wood) on cut or fill
slopes wherever possible.
3. Applicant shall show in the plan the general nature and extent of existing vegetation on the
tract, the location of trees in accordance with the requirements of the tree survey required
by Section 7.7.4.E of the DDC, the areas which will be preserved, altered, or removed as a
result of the proposed alterations.
4. Locations and construction details should be provided, showing how trees will be preserved
in areas which will be altered by filling or paving within the drip line of those trees.
5. Applicant shall also submit plans showing location, type, and size of new plant materials and
other landscape features planned for altered flood plain areas.
4.12 Drainage and Floodplain Easements
4.12.1 General
A. Drainage and floodplain easements shall be provided for all open natural streams or manmade
drainage facilities. Easements shall encompass all areas lower than a ground elevation defined as
being the highest of the following:
1. 15 feet outside the calculated fully developed water surface elevation and associated flood
boundary based on a design storm whose frequency is 100 years. All contributing watersheds
are to be treated as fully developed for purposes of calculating the water surface elevation.
2. The top of the high bank plus a minimum of 20 feet, if higher than stated in A.1. above.
3. Existing natural banks with a slope steeper than 4H:1V shall have the easement line no closer
than the intersection of a 4H:1V line extending from the toe of the slope to the proposed
grade at the top of the bank, plus an additional 15 feet.
4. Additional access area may be required according to the Section 4.12.2 below.
4.12.2 Storm Drain Easements
A. Above Ground Systems
Where an access road is required adjacent to a channel, an additional easement area of a minimum
width of 15 feet shall be provided. The maximum cross slope shall be 2%. All access roads adjacent
to improved channels shall be located within the drainage easement.
1. No structures, pavement, landscaping, or other above-ground man-made improvement shall
be placed in a drainage easement, except where the easement is a public or private open
space or park. Any such improvement within a drainage easement must be approved through
a design deviation request.
B. Closed Systems
1. Easements for closed drainage systems shall meet the following minimum standards as
shown below in Table 4.12-A.
Section 4: Stormwater Design Criteria
4.12 Drainage and Floodplain Easements
4.12.3 Channel Access
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Table 4.12-A: Easement Requirements for Closed Drainage
Systems
Pipe or Box Size Minimum Easement Width (feet)
36 inches and under 16
42 to 54 inches 20
60 to 66 inches 25
72 inches and above 30
2. Utilities such as water and sanitary sewer lines may share a portion of a drainage easement,
containing an underground enclosed drainage system where an additional easement width
for a minimum of 10 feet is added to create a public drainage and utility easement. No
utilities shall be located in any lined channel, pipe, or box in such a way as to interfere with
flow capacity or maintenance of or access to the channel, pipe or box.
3. A drainage easement shall be provided for the area within a required outfall channel or ditch
to the point where the flowline “day lights” on natural grade or matches existing topography.
4. To provide for maintenance, a drainage easement shall be provided at least 25 feet beyond
any outfall headwall.
5. No structures, pavement, landscaping, or other above-ground man-made improvement shall
be placed in a drainage easement containing a closed drainage facility.
4.12.3 Channel Access
A. Access areas and ramps shall be provided for all publicly maintained channels to allow for
maintenance of the channels. These access areas and ramps shall be contained within a drainage
easement. Access areas shall have a width of at least 12 feet, a minimum cross slope of 2%, and a
maximum cross slope of 5%.
B. Access easements shall be provided from the public ROW to the access area, if the access area is
not directly connected to the public ROW. Access easements shall remain free of obstacles that
block the use of the easement, including ungated fencing across the easement.
C. A concrete drive approach serving the access easement must be available and free of obstructions.
Any sidewalk crossing the access easement must be constructed using a residential street cross -
section, or otherwise designed to accommodate vehicle loads so that equipment may use the
access easement without damaging the sidewalk.
D. Access to all improved earthen channels shall be provided by one (1) of the following methods,
depending on the size and depth of the channel:
1. A clear access area must be provided on one side of the improved earthen channel along
the full length of the channel; or
2. If the channel is deeper than 4 feet or has a top width greater than 25 feet, an access area
must be provided on both sides along the full length of the channel. Access areas shall have
a width of at least 15 feet, a minimum cross slope of 2%, and a maximum cross slope of 5%.
E. All lined channels, and earthen channels with concrete pilot channels shall have a minimum bottom
width of ten (10) feet and shall be provided with concrete access ramps. Concrete access ramps
Section 4: Stormwater Design Criteria
4.13 Water Quality
4.13.1 Detention Facilities Easements
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shall have a minimum width of 12 feet, maximum slope of 6H:1V, and maximum cross slope of 5%.
All access roads shall be located within a dedicated easement. Access road pavement cross-sections
shall conform to the standards of the concrete residential street cross-section detail located in the
City of Denton Standard Details.
4.12.4 Detention Facilities Easements
A. Detention facility easements must encompass the entirety of the detention facility plus any required
maintenance access areas adjacent or leading to the facility.
B. All detention maintenance access easements must be connected to a public ROW, be a minimum
of 10 feet wide, and be free of obstructions which could prevent personnel and equipment from
accessing the detention facility.
4.12.5 Post-Construction Water Quality Control Structure Easements
A. All post-construction structural stormwater control structures must be located within an inspection
access easement. The intent of this easement is to allow City staff to access and inspect the control
structure to ensure it is being maintained in accordance with the SWFMA. This easement must be
connected to a public ROW, be a minimum of five (5) feet wide, and be free of obstructions which
could prevent City staff from accessing the control structure.
4.12.6 Fences
A. Fences in drainage easements are prohibited by the DDC, except as specifically provided for below.
1. Fences may crossin drainage easements that contain an underground stormwater system
may containprovided the fence is constructed with any type of non-masonry fence material
and if the fence is constructed with knock-out panels to facilitate maintenance.
2. Fences in drainage easements that contain overland flow may cross the easement if the fence
is constructed with wrought iron (pickets and rails), pipe, or pipe and cable. Fence height,
minimum picket spacing, and maximum ground clearance spacing shall be governed by
appropriate child safety measures.
3. No fences are allowed across inlet or outlet structures of drainage detention facilities. Fences
are permitted around the detention facility if they do not block or inhibit the flow conveyance
of the detention facility.
4. No fencing is allowed across easements which share water or wastewater facilities with the
drainage facility.
B. Fences in the floodplain are prohibited.
4.13 Water Quality
4.13.1 Water Quality Protection Volume
It is recommended required that all developments sites disturbing a land area larger than (1) one (1) acre
or part of a common plan of development disturbing a land area greater than (1) one (1) acre with one (1)
acre or more of disturbed land treat their stormwater runoff either through extended detention and/or
include site development controls necessary to remove 80% of the total suspended solids (TSS) from the
Section 4: Stormwater Design Criteria
4.13 Water Quality
4.13.3 Water Quality Hotspots
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water quality protection volume (WQV). See the iSWM™ Water Quality Protection Technical Manual for
information regarding the design of this WQV and appropriate discharge design. See the iSWMTM Site
Development Controls Technical Manual for information regarding structural stormwater controls and their
ability to remove pollutants in stormwater runoff to protect water quality. Any combination of structural
stormwater controls may be used to achieve the required recommended 80% TSS removal from all runoff
from impervious surfaces on the site. Any proposed proprietary treatment devices must be certified by
either the New Jersey Department of Environmental Protection (NJDEP), the Washington Sstate Technology
Assessment Protocol – Ecology (TAPE) program, or the Technology Acceptance Reciprocity Partnership
(TARP).
The percent TSS removal (%TSS) that is achieved on a site can be calculated using equation 4.8 below. This
equation is an area-weighted TSS reduction equation that accounts for the TSS reduction attributable to
each stormwater treatment best management practice (BMP) that is utilized on the site.
%𝑺𝑺𝑺= 𝚺𝒏 𝟎( 𝑺𝑺𝑺𝟎𝑨𝟎+ 𝑺𝑺𝑺𝟎𝑨𝟎+ … +𝑺𝑺𝑺𝒏𝑨𝒏)
𝚺𝒏𝟎 ( 𝑨𝟎+ 𝑨𝟎+ … +𝑨𝒏) [Eqn. 4.8]
Where: TSSn = TSS removal percentage for each structural BMP located on-site (%);
An = the area draining to each BMP (acres).
When two or more BMPs are used in series (stormwater discharges from one BMP into another), a different
calculation is necessary. This scenario is called a treatment train. Stormwater discharging from the upper
most BMP will be considerably “cleaner” than the influent, meaning TSS particle sizes will be much smaller.
Pollutant removal rates for BMPs used in a treatment train are not additive. To calculate the total % TSS
removal for a treatment train comprised of two or more structural BMPs, the following equation should be
used.
𝑺𝑺𝑺𝒕𝒓𝒂𝒊𝒏=𝑨+𝑨− 𝑨 ×𝑨
𝟎𝟎𝟎 [Eqn. 4.9]
Where: TSStrain = total TSS removal for treatment train (%);
A = % TSS removal of the first (upstream) BMP
B = % TSS removal of the second (downstream) BMP
4.13.2 Water Quality Hotspots
Not all structural stormwater controls are appropriate for receiving runoff from hotspots. Hotspots are land
uses or activities which produce higher concentrations of trace metals, hydrocarbons, or other priority
pollutants. Examples of hotspots might include gas stations, convenience stores, marinas, public works
storage areas, garbage transfer facilities, material storage sites, vehicle service and maintenance areas,
commercial nurseries, vehicle washing/steam cleaning sites, landfills, construction sites, industrial sites,
industrial rooftops, auto salvage or recycling facilities, and dog parks. Only appropriate structural
stormwater controls identified in the iSWMTM Site Development Controls Technical Manual may be used for
receiving hotspot runoff.
Facilities that discharge stormwater associated with industrial activity permitted under TCEQ Multi-Sector
General Permit (TXR050000) may incorporate WQv requirements into point source discharge control
requirements.
4.13.3 Required Stormwater Facility Maintenance Agreements
All private post-construction structural stormwater controls shall require a SWFMA in accordance with
Section 4.14 of this manual.
Section 4: Stormwater Design Criteria
4.13 Water Quality
4.13.4 Construction Erosion and Sediment Control Requirements
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4.13.4 Construction Erosion and Sediment Control Requirements
The criteria established in this Manual provide basic guidance for the design of erosion and sediment
control plans within the City of Denton. However, full responsibility and liability for proper design
remains with the designer. Users of this Manual should be knowledgeable and experienced in the
theory and application of best management practices (BMPs) for erosion and sediment control plans.
All land-disturbing activities must include provisions for erosion and sediment control in accordance with :
• DDC Subchapter 7.3: Land-Disturbing Activities
• DDC Subchapter 7.4: Environmentally Sensitive Areas
• The City of Denton Site Design Criteria Manual
• The City of Denton Construction Criteria Manual
• iSWM™ Criteria Manual for Site Development and Construction
• iSWM™ Technical Manual Planning Documents; and
• Public Works Construction Standards North Central Texas, Amended Fifth Edition (2023)
Other design criteria may be warranted from applicable resources. The Federal Government, the State of
Texas, NCTCOG, Denton County, Denton County Transit Authority (DCTA) and other related organizations
and resources shall be consulted for additional criteria as may be deemed necessary. Along with this Design
Manual, the DDC shall be consulted for additional guidance. The criteria established in this Manual do not
supersede the policies contained in the DDC. Any revision to the DDC supersedes the criteria in this Manual.
All land-disturbing activities must include provisions for erosion and sediment control in accordance with
Section 7.3 (Land-Disturbing Activities) of the DDC, the iSWM™ Water Quality Technical Manual, the iSWM™
Construction Controls Technical Manual, and the iSWM™ Site Development Technical Manual.
A. Erosion Control Plans
The purpose of the Erosion Control Plan is to reduce erosion, retain sedimentation and, to the
greatest extent, prevent off-site drainage during land-disturbing and construction activities. It does
this by assessing the site’s erosion potential to determine structural controls and site management
practices, also known as Best Management Practices (BMPs).
1. General Erosion Control Plan Requirements
All erosion control plan must contain the following:
a. A narrative description of the project, total acreage of the parcel, total acreage to be
disturbed, the construction sequence, the potential sources of erosion and
sedimentation, BMPs, their maintenance, and inspection procedures.
b. A list of BMPs that will be implemented during each phase of construction, such as
preservation of existing vegetation, stockpile management, silt fencing, outlet
protection, runoff interception, vegetated buffers, etc.
c. A sequence of construction of the development site, including stripping and clearing;
rough grading; construction of utilities, infrastructure, and buildings; and final grading
and landscaping. Sequencing shall identify the expected date on which clearing will
begin, the estimated duration of exposure of cleared areas, areas of clearing, installation
of temporary erosion and sediment control measures, and establishment of permanent
vegetation.
Section 4: Stormwater Design Criteria
4.13 Water Quality
4.13.4 Construction Erosion and Sediment Control Requirements
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d. Description of on-site spoils and borrow areas, including handling and disposal of
borrow materials, as well as size, depth of fill and revegetation procedures.
e. Descriptions of on-site and adjacent critical areas
f. Description of vegetative temporary and permanent stabilization practices
i. Areas within the limits of construction (LOC) that will require temporary
stabilization
ii. Seeding mixtures and rates, types of sod, method of seedbed preparation,
expected seeding dates, type and rate of lime and fertilizer application, and kind
and quantity of mulching for both temporary and permanent vegetative control
measures
iii. Specific limits on the time frame between initial exposure of soils by construction
activity to the temporary or final stabilization of those surfaces
iv. Schedule for converting temporary controls to permanent functions (e.g. basins)
g. Drawings and specifications of structural controls and site management practices, with
supporting calculations and assumptions
2. Phased Erosion Control Plans
Two-phased erosion control plans are required for non-linear projects with land-disturbing
activities totaling five (5) acres or greater. Plans must be shown on separate sheets, and must
also depict both existing and proposed contours.For projects with earthwork construction
totaling five (5) acres or more, a two-phased erosion control plan is required for all non-
linear projects. Each phase must be provided as a drawing on a separate plan sheet. Drawings
should address the transition between phases.
a. Phase 1 – Initial Land Disturbance: this phase must utilize sediment and erosion controls
prior to initial land disturbing activities and include structural controls that address low
point runoff.This drawing shows BMPs to be installed prior to general clearing of the
site. It should also show the existing contours, adjacent streets, ROW, easements and
property lines. Do not show final contours on this drawing.
i. Show the BMPs selected for the following:
a) Downslope perimeter controls
b) Side-slope controls as needed per site conditions
c) Controls that will intercept runoff
d) Access barriers for areas to remain undisturbed, such as ESA and tree
protection fencing
ii. Must show structures to be demolished and trees to be removed
iii. If installing sediment-trapping impoundments, such as sediment basins or
interceptor swales, they must be shown on this phase as they are installed at the
initiation of grading.
b. Phase 2 – Construction and Individual Lot Phase with Behind Curb ControlsStabilization:
This phase shows BMPs required during the rest of grading and construction, such as
inlet protection. It must also include BMPs appropriate for final stabilization; seeding,
sodding, flatwork, etc.
Section 4: Stormwater Design Criteria
4.13 Water Quality
4.13.4 Construction Erosion and Sediment Control Requirements
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Individual Lot Phase: For single-family residential developments, the Phase 2 plan will
also show behind-the-curb controls, such as silt fencing, ground cover, and stabilized
construction entrances.
3. For projects with earthwork construction totaling less than five (5) acres, phased erosion
control plans are not required; the erosion control plan may be shown on a single sheet with
the following:
a. Show existing contours
b. Show final contours
c. Show direction of flow during grading operations with arrows
d. Show areas to be permanently stabilized.this phase must require sediment and erosion
controls during the installation of public/private infrastructure and include any controls
to remain in place from Phase 1.
a. Behind the curb controls shall be installed upon the completion of street segments and
must be included in Phase 2.
B. Mass-Graded Drainage Area Map
Drainage area maps (DAMs) and calculations are required for all three (3) phases of development,
as detailed below and shown in Figure 4.12. In addition to an existing conditions drainage area map
(DAM) and proposed conditions DAM, sites with earthwork construction ten (10) acres or greater
must provide a mass-graded DAM showing interim contours and temporary drainage conditions
created by earthwork construction and soil-leveling activities.
1. General Mass-Graded Drainage Area Map Requirements
a. Show the delineation and contributing drainage area of temporary basins;
i. Temporary basins can only flow to existing features; do not show features from the
proposed drainage area map.
b. Show and label contours created by earthwork construction. Do not show precise
grades such as building footprints, lot lines, or finished floor elevations.
c. Show the direction of flow for each temporary basin using arrows.
d. Show the locations of any existing basins.
e. Show the locations of any temporary sediment-trapping impoundments, such as
sediment basins or traps, or interceptor swales (optional).
2. For Sites with Ten (10) Acres or More Common Drainage
a. Show and label the locations of any sediment-trapping impoundments, such as
sediment basins or traps, or interceptor swales.
b. Calculations for each phase shall utilize a two (2)-year, 24-hour storm for the design of
any hydraulic component of the erosion control plan including sediment basins, swales,
channels, berm height, weir length, or any other outlet or conveyance structure required
by the plan.
c. The DAM requirements for each Phase of development are as follows:
a. Phase 1: Existing Conditions DAM – existing contours and flow arrows reflecting pre-
development conditions.
b. Phase 2: Mass Graded DAM – interim contours and flow arrows reflecting mass graded
Section 4: Stormwater Design Criteria
4.13 Water Quality
4.13.4 Construction Erosion and Sediment Control Requirements
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conditions prior to the public/private infrastructure installation stage.
c. Phase 3: Proposed Conditions DAM – proposed contours and flow arrows reflecting
post-construction, stabilized conditions.
C. Sediment Basins
A sedimentation basin or similar sediment-trapping impoundment is required where 10 or more
acres drain to a common area during any phase of development. Where other sediment-trapping
devices are used, such as interceptor swales, the below requirements apply.
1. Sediment basins and other detention structures must provide storage volume for the runoff
from a 2-year, 24-hour storm. Calculations must be included with the erosion control plan.
2. Sediment basin(s) or impoundments must provide at least 3,600 cubic feet (cu. ft.) of storage
per acre drained until final stabilization of the contributing drainage area.
3. Sedimentation basins or impoundments must be designed by a PE licensed in Texas or a
Certified Professional in Erosion and Sediment Control (CPESC).
1.4. Sediment basins must be able to control and treat runoff within site boundaries; they should
be installed as close as possible to the disturbed area or sediment source as possible. capable
of controlling runoff at the site. Existing detention or retention ponds at the site may not be
appropriate, as determined by City review staff.
2.5. Sediment basins must be designed, constructed, and maintained to minimize mosquito
breeding habitats by minimizing the creation of standing water. Outlet structures shall be
designed to provide a minimum dewatering time of 36 hours and a maximum dewatering
time of 72 hours.
3.6. When discharging from sedimentation basins and impoundments, the permittee shallplan
must utilize outlet structures that withdraw water from the surface. If this is infeasible, a
reason must be provided to City review staff during planning.
D. VegetationVegetative stabilization is required for all permanent and temporary channels and
basins. Plant selection guidance is provided in the iSWM™ Landscape Technical Manual.
1. Criteria for Stabilization
You are required to stabilize exposed portions of your site in accordance with DDC § 7.3.5.E,
the TXR150000 CGP, the NPDES CGP, and federal “C&D Rule” permit requirements as found
in 40 CFR 450.21. To be considered adequately stabilized, you must meet the criteria below
depending on the type of cover you are using, either vegetative or non -vegetative:
a. Vegetative Stabilization: If you are vegetatively stabilizing any exposed portion of your
site through the use of seed or planted vegetation, you must provide established
uniform vegetation (e.g., evenly distributed without large bare areas), which provides
70 percent or more of the density of coverage that was provided by vegetation prior to
commencing earth-disturbing activities.
i. Immediately after seeding or planting the area to be vegetatively stabilized, to the
extent necessary to prevent erosion on the seeded or planted area, you must select,
design, and install non-vegetative erosion controls that provide cover (e.g., mulch,
rolled erosion control products) to the area while vegetation is becoming
established.
ii. For final stabilization, vegetative cover must be perennial
Section 4: Stormwater Design Criteria
4.13 Water Quality
4.13.4 Construction Erosion and Sediment Control Requirements
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b. Deadline to Initiate Stabilization: You must initiate soil stabilization measures
immediately whenever earth-disturbing activities have permanently or temporarily
ceased on any portion of the site.
i. The term “immediately” means as soon as practicable, but no later than the end of
the next workday, following the day when the earth-disturbing activities have
temporarily or permanently ceased.
ii. Earth-disturbing activities have temporarily ceased when clearing, grading, and
excavation within any area of the site that will not include permanent structures
will not resume (i.e., the land will be idle) for a period of 14 or more calendar days,
but such activities will resume in the future.
iii. The City closely adheres to the EPA’s Construction General Permit and will consider
any of the following types of activities to constitute the initiation of stabilization.
a) prepping the soil for vegetative or non-vegetative stabilization;
b) applying mulch or other non-vegetative product to the exposed area;
c) seeding or planting the exposed area;
d) starting any of the three activities stated just above on a portion of the area
to be stabilized, but not on the entire area; and
e) finalizing arrangements to have stabilization product fully installed in
compliance with the applicable deadline for completing stabilization
c. Deadline to Complete Stabilization Activities. As soon as practicable, but no later than
14 calendar days after the initiation of soil stabilization measures, you are required to
have completed:
i. All activities necessary to initially seed or plant the area to be stabilized.
ii. You are required to have stabilized the exposed portions of your site prior to
terminating permit coverage. You must submit your notice of termination (NOT)
within 30 calendar days of completing earth-disturbing activities at your site.
2. Vegetative stabilization is required for all permanent and temporary channels and basins.
Plant selection guidance is provided in the iSWM™ Landscape Technical Manual.
3. The erosion control plan must demonstrate reasonable preservation of trees and understory
and that the following criteria is demonstrated in selection of trees to be preserved or
removed:
a. Proximity of the trees critical root zone or drip line to proposed grading activity.
b. Permanent tree protection methods are employed to protect the preserved tree from
damage where the trees critical root zone may be impacted.
c. Other measures have been employed, including site design that improves the chances
for tree survival.
d. Temporary tree protection methods are adequately employed.
e. Construction methods for utility service to the site are used that allow protection and
preservation of additional trees, such as, tunneling under the critical root zone, tree
walls, or tree wells.
f. Utility trenching activities are indicated on the plan.
E. Structural Controls and Site Management Practices
Section 4: Stormwater Design Criteria
4.13 Water Quality
4.13.4 Construction Erosion and Sediment Control Requirements
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1. Erosion and sediment control BMP design criteria shall adhere to the most current version
of the iSWM™ Construction Controls Technical Manual, unless one of the following
exceptions applies:
a. Linear projects may follow TxDOT standards; or
b. Proprietary erosion or sediment control devices may be utilized when:
i. Independent performance data is provided to prove a demonstrated capability of
meeting a stormwater management efficiency equivalent to iSWM™ methods; and
ii. Supplementary data for systems or devices, such as instruction manuals and
specification sheets, are provided and are demonstrated to be appropriate for use
in North Central Texas site conditions, as determined by Environmental Services
and Sustainability (ESS) department staff.
2. The City has restrictions on certain structural controls:
a. Curb inlet protection requires ESS approval to be used on active City streets
i. Organic filter tube curb inlet protection is prohibited
ii. Block and gravel filter curb inlet protection is prohibited
iii. Curb rock sock on-grade curb inlet protection is prohibited
F. Procedures During Construction
The Watershed Protection Division of the Environmental Services & Sustainability Department is
primarily responsible for the inspection and enforcement of erosion and sedimentation control
requirements on site developments and subdivisions. The City will m onitor compliance with plan
requirements and judge the effectiveness of the controls during different stages of construction
and before and after significant rainfall. The criteria and procedures contained in this section closely
adhere to DDC § 7.3.4-6, the TXR150000 CGP, the NPDES CGP, and federal permit requirements as
found in 40 CFR 122.26 & 123.25.
1. Criteria for Approvals Required Prior to the Commencement of Land-Disturbing Activities
a. The project must have a valid, current city development permit or site plan.
b. The developer, owner, or otherwise delegated applicant shall complete the appropriate
survey(s)
i. Applicants requiring a demolition permit must complete the Demolition Survey
ii. Applicants requiring all other permits must complete the Construction Survey
c. The applicant shall provide approved site plans and specifications for the development
permit. For plans to be accepted, the locations and dimensions of all temporary and
permanent erosion and sediment controls must be depicted. Specifications must
include the maintenance routines, and schedules for installation and removal of
controls, through all phases of construction.
d. If the project requires a Stormwater Pollution Prevention Plan (SWPPP), the plan must
be reviewed for completeness by City staff.
i. The SWPPP must show consistency with City-approved plans (i.e. civil engineering
plans and zoning compliance plans)
Section 4: Stormwater Design Criteria
4.13 Water Quality
4.13.4 Construction Erosion and Sediment Control Requirements
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e. Projects disturbing five (5) or more acres must submit a Notice of Intent to the City; or
when the project is part of a common plan of development with disturbed acreage
totaling five acres or more.
f. Construction Site Notice (CSN)
i. Executed CSN(s) are included in the SWPPP.
ii. CSN(s) are posted publicly in locations near the site entrance, where they can be
viewed by the general public.
2. Compliance Inspection by the City
a. The project must pass an initial inspection for approval of permits and/or Notice to
Proceed.
i. The project must be in substantial compliance with the approved plans and
specifications (ESCP) for the development permit
ii. Controls must be installed in all required areas, such as:
a) Perimeter controls
b) Stabilized construction exit
c) Protection of existing inlets
iii. Clearing for the installation of erosion control devices shall not exceed a width of
eight (8) feet and must not encroach into the dripline or critical root zone of any
tree to be protected.
b. The project will be routinely inspected during all phases of development to determine
the compliance or non-compliance of a project's temporary erosion and sedimentation
controls.
i. Erosion and sediment controls must be installed for current development phase.
ii. Sediment basins (when required) must be installed at the initiation of grading at
the associated drainage area; the deadline for installation is seven days after
initiation.
iii. Vegetative temporary stabilization measures must demonstrate consistent
progress toward stabilization. See previous section for criteria.
iv. Permanent stabilization must be initiated within 48 hours of completion of
construction activities on areas of the site and completed for project prior to
issuance of final Certificate of Occupancy.
v. Vegetative stabilization must demonstrate consistent progress toward 70% density
of perennial vegetative cover.
3. Reinspection
a. Reinspection is conducted for sites that are out of compliance.
i. Standard timeframe for corrections is seven (7) business days.
ii. Enforcement may be escalated if there are impacts to offsite property or waterways.
iii. A reinspection fee may be assessed.
b. Reinspection with Notice of Violation (NOV) will be issued for continued stormwater
non-compliance affecting stormwater, with reinspection fee assessed.
Section 4: Stormwater Design Criteria
4.13 Water Quality
4.13.4 Construction Erosion and Sediment Control Requirements
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c. Reinspection with Stop Work Order (SWO) – Escalation issued for continued non-
compliance affecting stormwater through failed erosion and sediment controls.
Reinspection fee assessed.
i. Effective until deficiencies are corrected.
ii. Erosion and sediment control failures which threaten life or property may result in
SWO without prior reinspection or NOV.
d. Reinspection Fees
i. Applicability – applies only to reinspection due to failure to comply with site
stormwater quality requirements.
ii. Amount – As established in the Water and Wastewater Rate Book.
iii. Time of Payment – Payment is due per standard City of Denton utility billing dates.
Erosion and sediment control BMP design criteria shall adhere to the most current
version of the iSWM™ Construction Controls Technical Manual, unless one of the
following exceptions applies:
Linear projects may follow TxDOT standards; or
Proprietary erosion or sediment control devices may be utilized when:
Independent performance data is provided to prove a demonstrated capability of
meeting a stormwater management efficiency equivalent to iSWM™ methods; and
Supplementary data for systems or devices, such as instruction manuals and
specification sheets, are provided and are demonstrated to be appropriate for use in
North Central Texas site conditions, as determined by City review staff.
Filter Tube Curb Inlet Protection and Rock Sock Curb Inlet Protection methods are
prohibited.
Wire Weir Curb Inlet Protection is not allowed on active City streets unless approved by
City Watershed Protection.
Section 4: Stormwater Design Criteria
4.14 Stormwater Facility Maintenance Agreements
4.14.2 Maintenance Agreements
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Figure 4.12 Drainage area map examples required for the three (3) development phases
4.14 Stormwater Facility Maintenance Agreements
4.14.1 Maintenance Agreements
All drainage improvements constructed within a development and any existing or natural drainage systems
shall require a maintenance agreement that identifies responsible parties for maintenance. The maintenance
agreement shall be written such that it remains in force upon sale of transfer of the property.
As part of the Operations and Maintenance Plan submittal, a SWFMA must be prepared by the engineer of
record for each stormwater control that will not be wholly maintained by the City. This agreement must
outline preventive maintenance tasks and major repairs, identify the schedule for each task, assign clear
roles to affected parties, and provide a maintenance checklist to guide future owners, including an annual
self-inspection to be provided to the City. Multiple stormwater controls may be contained within a single
Stormwater Facility Maintenance Agreement. When areas are identified for detention that also ser ve other
purposes for the development (e.g. parking lots, loading docks) the requirement for a SWFMA may be
waived.
4.14.2 Private Maintenance (SWFMA Required)
A. Private drainage facilities include those drainage improvements which are located on private
Section 4: Stormwater Design Criteria
4.14 Stormwater Facility Maintenance Agreements
4.14.3 Maintenance Agreement Requirements
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property and which serve the needs of private development.
B. Private drainage facilities may also include detention or retention ponds, dams, and retaining walls
intended to direct or contain runoff. Such facilities must be designed in accordance with sound
engineering practices and reviewed and inspected by the City.
C. All SWFMA exhibits shall be reviewed and approved by the City with the civil engineering plans.
The agreement for perpetual maintenance of private drainage facilities shall be executed with the
City during per-construction. This agreement shall run with the land and can be tied to commercial
property or to an owner’s association, but not to individual residential lots.
D. The SWFMA shall provide the City with access to all private drainage facilities.
4.14.3 Maintenance Agreement Requirements
Details of the SWFMA must be set forth in a series of exhibits:
A. Exhibit A Legal Description - This includes the Metes and Bounds, a Surveyor’s Drawing of the area
occupied by the facility, and a copy of the preliminary or recorded plat containing the facility.
B. Exhibit B Design Plan and Specifications - These are summary documents intended for the use of
future owners in conducting routine maintenance, inspections, and repairs. The documents include:
1. Design Data and Calculations - This can be in the form of a letter or statement from the
engineer of record which summarizes critical design calculations related to the functionality
of the facility, such as storage volume or TSS removal, and attests to the facility conforming
to applicable iSWM standards;
2. Schematic Plan - This should be prepared by the engineer of record from construction
drawings to show the general layout of the facility. Major features requiring regular or special
maintenance should be shown and labeled in general terms understandable to a layman. A
profile should be given showing critical elevations that control the function and capacity of
the facility, and one or more cross-sections should be provided to indicate the general
grading of the facility. A typical example of a schematic plan for a simple detention basin is
shown in Figure 4.13 below; and
3. Landscaping - Vegetation should be shown consistent with the accepted Landscape Plan,
either on the Schematic Plan or as a separate drawing.
C. Exhibit C Operations and Maintenance Plan - Specific maintenance tasks should be defined for each
element of the facility. Maintenance tasks specific to the facility should be described in simple terms
consistent with terminology contained in the Schematic and Landscape plans. An inspection and
maintenance frequency should be established for each task.
D. Exhibit D Maintenance Checklist - A checklist consistent with the Operations and Maintenance Plan
shall be provided for the use of future owners in performing routine and special maintenance tasks.
This list should describe work required and frequency in language that is easy to understand and
specific for the facility to be maintained. This form will be completed by the Owner and submitted
to the City annually as part of a regular self -inspection program. See Appendix A for an example
checklist for preparing a SWFMA for a simple detention basin.
Additional facility maintenance guidance for several types of stormwater controls is provided in the iSWM
Technical Manual. The engineer of record must certify that the construction has been completed in
accordance with the general plans and Schematic Plan. After approval of construction by the City, the
Section 4: Stormwater Design Criteria
4.14 Stormwater Facility Maintenance Agreements
4.14.3 Maintenance Agreement Requirements
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engineer of record is expected to provide guidance to the owner’s representative in implementing the
accepted maintenance program and to co-sign the first annual inspection after the construction.
Figure 4.12 Simple Detention Basin Plan Schematic
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Section 5: Transportation Design Criteria
5.1 Overview
The purpose of Section 5 – Transportation Design Criteria is to provide minimum guidelines for the design
and construction of transportation infrastructure within the City of Denton, Texas and its extraterritorial
jurisdictions using the complete street and context-sensitive solution approach. The goal is to create safer,
more livable places that are consistent with their social, environmental and economic values.
It is the responsibility of the design engineer to ensure the final design of transportation infrastructure are
in conformance with the most recently adopted versions of the following documents:
A. City of Denton Mobility Plan;,
B. City of Denton Code of Ordinances, Chapter 18 – Motor Vehicles and Traffic, and Chapter 25 –
Streets, Sidewalks and Public Places;,
C. The North Central Texas Council of Governments (NCTCOG) Public Works Construction Standards,;
D. DDC Subchapter 7.8 – Access and Circulation;,
D.
E. DDC Subchapter 7.9 – Parking and Loading;,
E.F. DDC Subchapter 8.3 – Subdivision Design,;
F.G. Americans with Disabilities Act (ADA) Standards for Accessible Design;,
G.H. Public Right-of-Way Accessibility Guidelines (PROWAG);,
H.I. The International Fire Code (IFC);,
I.J. this Manual,; and
J.K. relevant TxDOT, USDOT, NCHRP, FHWA, and AASHTO publications.
The criteria established in this Manual provide basic guidance for the design of transportation systems
within the City of Denton. However, full responsibility and liability for proper design remains with the
design engineer. Users of this Manual should be knowledgeable and experienced in the theory and
application of transportation engineering.
Other design criteria may be warranted from applicable resources. The Federal Government, the State of
Texas, NCTCOG, Denton County, Denton County Transit Authority (DCTA) and other related organizations
and resources shall be consulted for additional criteria as may be deemed necessary. Along with this Design
Manual, the DDC shall be consulted for additional guidance. The criteria established in this Manual do not
supersede the policies contained in the DDC. Any revision to the DDC supersedes the criteria in this Manual.
5.1.1 Organization
Section 5 - Transportation Design Criteria is organized as follows:
A. Overview
B. Mobility Framework
C. Roadway Design
Section 5: Transportation Design Criteria
5.2 Mobility Framework
5.2.1 Roadway Functional Classifications
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D. Intersection Design
E. Auxiliary Roadway Design
F. Access Management
G. Bike and Pedestrian Facility Design
H. Transit Facility Design
I. Traffic Impact Analysis Guidelines
J. Pavement Design Standard
K. Complete and Context-Sensitive Streets
5.2 Mobility Framework
The City of Denton Mobility Plan should be reviewed relative to any proposed development.
It should be noted that the City of Denton Mobility Plan is a living document and is periodically updated to
reflect the changes in the characteristics of anticipated traffic flow within the City.
5.2.1 Roadway Functional Classifications
The City of Denton Mobility Plan provides definitions for the street classifications. These street classifications
apply to developments and/or street improvements within the City of Denton and are to be used for design
purposes. These classifications were established in the Thoroughfare Plan based upon expected fully
developed traffic volumes.The City of Denton uses the following roadway functional classifications in
guiding developments and street improvements within its jurisdiction. They are to be used in conjunction
with other Ccity of Denton documents, as well as Complete Streets, Vision Zero, and Context- Sensitive
Design considerations. These classifications were established in the Thoroughfare Plan based upon
expected fully developed traffic volumes.
A. Freeway
Freeways are streets that are intended to move large volumes of traffic through and around the
City and are typically maintained by the TxDOT. These street types are to have limited access as
defined in Section 5.6 Access Management section of this Manual.
Freeways in the region typically have high design speeds and have on‐ and off‐ ramps to control
access. In urban areas, these freeways have adjacent frontage roads that provide access to adjacent
business that may front onto the corridor.Freeways are high-capacity roadways intended to move
large volumes of traffic through the region, into, and out of the City of Denton. They are typically
managed and maintained by external agencies such as the Texas Department of Transportation
(TxDOT) and may include tolled or non-tolled facilities. Freeways are limited-access facilities as
defined in Section 5.6 (Access Management) of this Manual.
These facilities are designed as multi-lane, high-speed roadways with on- and off-ramps to control
access and support long-distance regional and interstate travel. In urban areas, freeways are often
accompanied by frontage roads that provide access to adjacent properties and businesses.
This Manual does not prescribe specific design standards for freeways, as their planning, design,
and construction fall under the jurisdiction of TxDOT or other applicable agencies.
Section 5: Transportation Design Criteria
5.2 Mobility Framework
5.2.1 Roadway Functional Classifications
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B. Primary Arterial
Arterial streets are streets that serve major routes into and through the City of Denton. They are
often multi-lane thoroughfares that generally include a landscaped median. Arterial streets are
shown on the City Mobility Plan. These street types are to have limited access as defined in Section
5.6 Access Management section of this Manual.
Primary arterials provide regional connectivity between different areas of Denton County and the
DFW region. The design of arterial can vary depending on the surrounding land use and
development. In urban areas, arterials may have wider sidewalks with smaller building setbacks,
while suburban areas may have limited sidewalks with a larger buffer between the edge of the street
and the building fronts. Refer to City of Denton Standard Details T112A and T112C for typical cross-
section requirements and design guidance.
C. Secondary Arterial
Secondary arterials provide shorter connections and carry less traffic. Secondary arterials are still
significant to vehicular travel as they serve trips of moderate length and provide more land access.
They have a greater role in balancing local land access with moving people and goods. Typically,
they have lower travel speeds and traffic volumes than Primary arterials. They also tend to be limited
in width by the built environment that they serve and often have the greatest need for
accommodation of high levels of use for all travel modes. Refer to City of Denton Standard Details
T110A and T110C for typical cross-section requirements and design guidance.
D. Major Collector Street
A major collector is a roadway that collects and distributes traffic between collector streets/ local
streets and arterial roads, supporting moderate traffic volumes. It typically accommodates 2–4 lanes
and operates at lower speeds. Major collectors balance mobility and access, featuring wider lanes,
occasional medians, and turn lanes to improve flow. These roads often include sidewalks, bike lanes,
or shared-use paths, making them suitable for moderate-distance trips between neighborhoods,
schools, and commercial areas. Refer to City of Denton Standard Details T113A-T1135A and T113C-
T1153C for typical cross-section requirements and design guidance.
D.E. Collectors Street
A collector street is a street that collects associated traffic from residential streets, rural streets,
commercial streets, or industrial streets as designated on the City Mobility Plan.
Collectors in the City of Denton provide local land access and traffic circulation from residential
neighborhoods to arterials or/ major collectors. They typically experience lower traffic volumes and
have lower design speeds. Collector classifications include the following:
1. Commercial Collector – Provides circulation between commercial developments and the arterial
or /major collector system. Refer to City of Denton Standard Details T108A and T108C for cross-
section requirements and design guidance.
Residential Collector – Functions as a residential street but is designed to accommodate higher
traffic volumes and wider pavement widths than standard residential streets. Parking may be
permitted depending on the context and adjacent land uses. Refer to City of Denton Standard
Details T107A and T107C for cross-section requirements and design guidance.
E.F. Local Streets
Section 5: Transportation Design Criteria
5.2 Mobility Framework
5.2.2 Auxiliary Roadway Classifications
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A local street is a public street that provides access to adjacent property and are usually contained
within the neighborhood. These streets have low speeds and low volumes associated with them.
Local streets may be further classified into the following two (2) types:
1. Residential Street – A residential street is a public street associated with residential
development within an urban environment. The residential street may require parking or
prohibit parking, accommodate on-street parking, dependent on use the context and
adjacent land uses. Refer to City of Denton Standard Details T105A and T105C for cross-
section requirements and design guidance.
2. Rural or/ Suburban Residential Street – A rural street is a public street that connects rural
communities. Refer to City of Denton Standard Details T106A and T106C for cross-section
requirements and design guidance.
Existing or new industrial developments on local streets shall consult with the City’s Engineer.
5.2.2 Auxiliary Roadway Classifications
Roadways that cannot be classified as thoroughfare, are grouped together as auxiliary roadways and are
classified here as follows:
A. Alleys
An alley (residential or commercial) is designed to provide access to the rear of or side of a lot
including solid waste and fire access. These pathways are narrower than standard streets, usually
measuring 20 feet wide public ROW right-of-way, and are not intended for through traffic but rather
for serving adjacent properties. Alleys will be required for residential streets prohibiting on-street
parking. Alleys are required in non-residential zoning districts where necessary to provide for
adequate access for service vehicles, off-street loading or unloading, access for emergency vehicles,
fire access or similar reasons consistent with the intent of the DDC.
B. Drives
A drive is an unobstructed paved area providing vehicular access from a street to a developed
property. Drives can be classified as follows:
1. Driveway - A driveway is located entirely on private property. It is only for a single-family or
a duplex property. It connects a drive approach to a garage, carport, parking pad or the like.
2. Drive Aisle - A drive aisle is located entirely on private property. It is for every other condition
other than for a single-family or a duplex property. It connects a drive approach to an area(s)
that is to be accessed on the site such as, but not limited to: parking space(s); loading dock(s);
loading area(s) (marked or implied - for passengers and/or goods); porte-cochere(s), and/or
the like. It can also be a fire lanefire apparatus access road (in and of itself or in conjunction
with other access use[s]). It can also be an access to an adjoining property (in and of itself
or in conjunction with other access use[s]).
3. Drive Approach - A drive approach connects a street (city, public or private) or highway
(TxDOT) with a drive aisle. Some features of the drive approach may extend into and be a
part of the driveway or drive aisle. The drive approach is measured from the face of the
roadway curb to the end of the curb return radius on the private property. The following
provides the types of drive approaches considered within this Manual:
a. Single-family residential: A drive approach to a single-family residential lot or one lot
duplex.
Section 5: Transportation Design Criteria
5.3 Roadway Design
5.3.1 Design Controls
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b. Multifamily residential: A drive approach to a multifamily lot such as triplexes,
fourplexes, and multi-complexes. The drive approach can be either the main entrance
approach or the secondary entrance approach. Each type has specific design
requirements.
c. Commercial: A drive approach to a commercial development. The drive approach can
be either the main entrance approach or the secondary entrance approach. Each type
has specific design requirements.
d. Industrial: A drive approach to an industrial development. The drive approach can be
either the main entrance approach or the secondary entrance approach. Each type has
specific design requirements.
e. Mixed-use approach: A drive approach that is a mixed-use development shall consider
the more stringent criteria for the approach design.
4. Flag Drives - A flag drive is a private road within a private access easement, which may serve
up to three (3) residential dwelling units. Flag drives shall have direct access to a public street
other than an alley. They shall not, however, provide direct access to an arterial street.
C. Cul-De-Sacs, Dead-End Street, and Hammerhead Turnarounds
A Cul-De-Sac is a dead-end street that has a fire-accessible turnaround at the end of the street. A
half Cul-De-Sac is a street bend at 90±5 degrees for residential and collector streets. Dead-end
streets and cul-de-sac should be avoided if possible to enhance street connectivity.A cul-de-sac is
a form of dead-end street that terminates with a circular or bulb-shaped turnaround, designed to
accommodate fire apparatus and
ther large vehicles for safe and efficient maneuvering.
A half cul-de-sac incorporates a 90° ± 5° bend, typically applied to residential or residential collector
streets, and provides limited turnaround capability. In contrast, traditional dead-end streets share
similar geometric characteristics with cul-de-sacs but terminate abruptly without a defined
turnaround, restricting emergency access and vehicular circulation.
Hammerhead turnarounds are configured in a T-shaped or L-shaped layout at the end of a dead-
end street, providing adequate space for large vehicles to complete a three-point turn. This option
is commonly applied in constrained sites where a full cul-de-sac is not feasible.
To support overall street connectivity and circulation, the use of cul-de-sacs, dead-end streets and
hammerhead turnarounds should be minimized whenever practicable avoided if possible. For
detailed design guidance, refer to Section 5.5.3 (Cul-de-Sac) and Section 5.5.4 (Hammerhead
Turnarounds) of this manual.
5.3 Roadway Design
5.3.1 Design Controls
Traffic volumes and speed are necessary for the design of roadways, and assist with the planning and design
of ROW, number of lanes, turn-lanes, need of intersections, and bicycle and pedestrian facilities. Guidance
on these design controls will be discussed at the pre-design meeting.
Section 5: Transportation Design Criteria
5.3 Roadway Design
5.3.2 Street Sections
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5.3.2 Street Sections
Street section standards are provided for arterial, collector, and local streets in Table 5.3-A below. Refer to
the City of Denton Standard Details for cross-section details. Options for street sections are dependent
upon treatment utilization within the street section. Besides defined lanes , other treatments that can be
utilized within the street sections include on-street parking, bike lanes, multi-use paths, and transit facilities.
The intent is to provide options in order to develop a “complete street” with “context-sensitive” design; See
Section 5.11 of this Manual. ROW requirements may vary at intersections based upon turning movement
requirements.
In general, street grades shall follow the natural contour of the property and be below the existing grade
so that the parkway drains towards the street. Excessive cuts and fills solely for the purpose of balancing
earthwork are not permitted.
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Table 5.3-A : Geometric Roadway Standards
Criteria
Roadway Classification
FREEWAY PRIMARY
ARTERIAL
SECONDARY
ARTERIAL
SECONDARY
ARTERIAL
(ONE-WAY)
MAJOR
COLLECTOR
COMMERCIAL
COLLECTOR
RESIDENTIAL
COLLECTOR RESIDENTIAL
RURAL OR
SUBURBAN
RESIDENTIAL
ALLEY [6,7]
No. of Lanes [1]
As per
TxDOT
standards
6 4 2-3 3-4 3 2-3 2 2 2
Min. ROW [10] 135’ 110’ Refer to note
[12]65’ 110’ 65’ 65’ 55’ 65’ 20’
Pavement Width [2] (BOC to BOC) 84’ 62’ Refer to note
[12]35’ 48’-72’ 39’ 39’ 33’ 21’ [5] 15’ [5]
Median Width 14’ 14’ NA 0’-14’ NA NA NA NA NA
Parkway Width 25.5’ 24’ Refer to note
[12]15’ 18’-31’ 13’ 13’ 11’ 20’ NA
Min. Center Line Radius [3] 750’ 575’ 575’ 575’ 575’ 400’ 200’ 200’ 100’
Min. Horizontal Curve Separation 100’ 100’ 100’ 100’ 100’ 100’ NA NA NA
Min. Grade (%) 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5
Max. Grade [4] (%) 7 7 7 7 7 7 10 10 8
Design Speed (MPH) 40-45 35-40 30-35 30-35 30-35 30 30 30 10-15
On-street Parking Prohibited Prohibited Permitted [8] Prohibited [9] Prohibited Permitted [8] Permitted [8] Prohibited Prohibited
Notes:
[1] The number of travel lanes is dependent upon TIA and/or the City’s Engineer’s requirements.
[2] See , Table 5.4- G, and Table 5.4- H for additional ROW requirements at intersections with turn lanes.
[3] The mMinimum center line radius is based on the cross slope of -2% (no superelevation).
[4] The maximum grade within 60 feet of an intersection measured from the intersection curb is 2% or less.
[5] Measurement is edge-of-pavement to edge-of-pavement.
[6] If an alley is to be used for waste collection, it must meet all alleyway access requirements shown in Section 3: Solid Waste Design Criteria of this Manual.
[7] If an alley is intended to provide fire apparatus access, it must meet the design requirements of Section 5.6.3- Fire Apparatus Access Roads of this Manual.
[8] Parking is allowed unless otherwise prohibited by ordinance or by signs installed by the city.
[9] Parking is prohibited unless otherwise allowed by ordinance or by the City’s Engineer, in which case only parallel parking is permitted.
[10] The developer shall dedicate from one-half of the required ROWright-of-way, measured from the centerline of the existing street alignment, up to the full width of the required ROWright-of-way for City-
maintained facilities, in accordance with the City of Denton Mobility Plan.
[11] A 20-ft wide public utility easement is required along the property frontage where the property abuts a TxDOT-maintained roadway.
[12] The applicable standards, cross-sections, and design requirements shall be determined in coordination with the City Transportation Departmentivision.
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Table 5.3-A: Geometric Roadway Standards
Roadway Classification No. of
Lanes 1
Min.
ROW
(feet)
Min.
B-B
Width 2
(feet)
Min.
Center Line
Radius 3
(feet)
Min.
Horizontal
Curve
Separation
(feet)
Min.
Grade
(%)
Max.
Grade 4
(%)
Freeway As per TxDOT standards
Primary Arterial 6 135 104 750 100 0.5 7
Primary Arterial – Modified 6 135 88 750 100 0.5 7
Secondary Arterial 4 110 80 575 100 0.5 7
Secondary Arterial – Modified 4 110 67 575 100 0.5 7
Collector – Commercial 2 65 39 575 100 0.5 7
Collector – Residential 2 65 39 400 100 0.5 7
Local – Residential 2 55 33 200 0 0.5 10
Local – Rural 2 65 25 5 200 0 0.5 10
Local – Alley 6 1 20 15 5 100 0 0.5 8
Notes:
[1] Number of travel lanes dependent upon TIA and/or City’s Engineer’s requirements.
[2] See Table 5.4-D, Table 5.4-E, and Table 5.4-F for additional ROW requirements at intersections with turn lanes.
[3] Minimum center line radius based on cross slope of -2% (no super elevation).
[4] Maximum grade within 60 feet of an intersection measured from the intersection curb is 2% or less.
[5] Measurement is edge-of-pavement to edge-of-pavement.
[6] If an alley is to be used for waste collection, then it must meet all alleyway access requirements shown in Section 3: Solid Waste Design
Criteria of this Manual.
5.4 Intersection Design
Several components of intersection design are addressed in this section. These standards are to work in
concert with the Traffic Impact Analysis (TIA) requirements of this Manual. Additionally, the Pedestrian and
Bicycle Facility Design, Transit Facility Design, and the City of Denton Standard drawings for accessibility
should be reviewed for additional design requirements.
5.4.1 Geometry
A. Street intersections should be designed to be perpendicular; see tolerances shown in Table 5.4-A
below. All streets shall be aligned with any existing streets by continuation of the centerline thereof.
B. The staggering of street alignment resulting in “T” intersections shall leave a minimum distance of
150 feet between the curb faces centerlines of residential streets, and 200 feet between the curb
faces centerline of collector streets.
C. Table 5.4-A and Figure 5.1 below provide requirements for ROW corner clips and curb return radius
at intersections. These standards provide minimum vision clearance areas without consideration
to stopping sight distance. Additional sight clearance evaluation should be performed as necessary,
as per Section 5.4.3 below.
Section 5: Transportation Design Criteria
5.4 Intersection Design
5.4.2 Visibility Standards
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Figure 5.1 Minimum Vision Clearance
Table 5.4-A: Intersection Geometry
Intersection Classification Intersection Angle
(degrees)
ROW
Corner Clip 1 (feet)
Curb Return
Radius (feet)
Arterial - Arterial 90±5 30 30
Collector - Arterial 90±5 20 30
Collector - Collector 90±5 15 30
Residential Street - Arterial 90±5 15 30
Residential Street - Collector 90±10 15 20
Residential Street - Residential Street 90±10 10 20
Flag Drive - Collector 90±10 5 20
Flag Drive - Residential Street 90±15 5 10
Alley - Collector 90±10 10 30
Alley - Residential Street 90±10 15 30
Alley - Alley 90±10 25 30
Notes:
[1] Shall apply to all corners of the intersection.
[2] Fences must provide a 5-ft. corner clip adjacent to driveways.
[3] Curb Return Radius is for single lane design. Multi-lane and special considerations for truck-turning radius require turn radius
analysis, as required by the City’s Engineer.
[4] Major Collector shall follow the arterial street standard.
5.4.2 Visibility Standards
Table 5.4-B and Figure 5.2 below shall be used to evaluate the required unobstructed view for motorists at
intersections, which are based upon the design speed approaching the intersection. Design speeds are
based upon the roadway classification. The values shown in the table are minimum standards. Within the
sight line area, no obstruction shall be allowed that will obstruct the view of motorists. A sight visibility
easement shall be dedicated to protect and maintain sight visibility.
A. Table 5.4-B below is based upon passenger car right turn and left turn from stop. Where truck
traffic warrants additional sight distance, refer to AASHTO Geometric Design of Highways and
Streets for single-unit truck and combination truck design requirements, Case B1 and Case B2.
B. Refer to AASHTO Geometric Design of Highways and Streets for multi-lane considerations and
other design considerations that may apply for Cases “A” through “F”.
C. Lines of sight distance at all intersections shall be clear at an elevation between two (2) feet and
Section 5: Transportation Design Criteria
5.4 Intersection Design
5.4.3 Vertical Curve Standards
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nine (9) feet above the nearest gutter elevation.
Figure 5.2 Visibility Standards
Table 5.4-B: Visibility Standards
Design Speed
(mph)
Intersection Sight Distance
Near Side (feet)
Intersection Sight Distance
FarNear Side (feet)
30 290 335
35 335 390
40 385 445
45 430 500
Notes:
[1] Driveways accessing roadways shall use above table to satisfy intersection visibility compliance.
5.4.3 Vertical Curve Standards
Vertical curves are required when two (2) street grades intersect at a point of vertical intersection greater
than 1%. Minimum vertical lengths for both crests or sags shall be defined by the design speed for the
street and the associated stopping sight distance, as well as the minimum K value. Table 5.4-C below shows
the minimum K value for various design speeds.
Table 5.4-C: Minimum ‘K’ Values for Vertical Curves
Design Speed
(mph)
Stopping Sight
Distance (feet)
Crest Vertical Curve
(K Min)
SAG Vertical Curve
(K Min)
30 200 19 37
35 250 29 49
40 305 44 64
45 360 61 79
Notes:
[1] Source: AASHTO Geometric Design of Highways and Streets ‘US Greenbook’.
Section 5: Transportation Design Criteria
5.4 Intersection Design
5.4.4 Turn Lane Requirements
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Vertical curve lengths can be calculated as shown in Equation 5.1 below:
L = KA [Eqn. 5.1]
Where: L = Vertical Curve Length
A = Algebraic Difference in Grade
A. No vertical curve required for “A” equal to or less than 1.0%
B. Minimum spacing between successive vertical curves shall be 50 feet for residential, and 100 feet
for collectors and arterials.
C. Resultant vertical curve grade shall be no less than 0.3% for concrete pavement, and no less than
0.5% for asphalt pavement.
D. For drainage purposes, 50-ft. vertical curves are required when “A” is greater than 1.0% and less
than or equal to 1.2%. Otherwise minimum vertical curve length is 100 feet.
5.4.4 Turn Lane Requirements
Turning lane requirements shall be based upon the following requirements and/or the requirements of the
City’s Engineer, and the tables within this section.
A. Left-Turn Lane Warrants
When designing an intersection that provides direct or indirect access to the proposed
development, left-turn lanes should be provided at driveways and street intersections along major
arterial and collector roads, wherever left turns are permitted. Traffic-volume-based guidelines for
where left-turn lanes should be provided are presented in :
Tables 5.4-D (for four-lane roadways) and
Table 5.4-E for (two-lane roadways) below.
Table 5.4-D below provides criteria which warrant left-turn lanes. Figure 5.3 below provides
guidance on left-turn lane requirements.
Conditions for requesting a left-turn lane include large truck volume, high crash history, limited
sight distance, and significant delay for motorists to make the turn, as determined by the City’s
Engineer.
Table 5.4-D: Left-Turn Warrants for Four-Lane Roadways [1]
Source: AASHTO A Policy on Geometric Design of Highways and Streets
Left-Turn Lane Peak-
Hour Volume
(veh/hr)
Three-Leg Intersection,
Arterial/Collector Volume
(vehicles per hour per lane)
that Warrants a Left-Turn Lane
Three-Leg Intersection, Major-Road
Peak-Hour Volume (veh/hr/ln) that
Warrants a Left-Turn Lane
Four-Leg Intersection,
Arterial/Collector Volume
(vehicles per hour per lane)
that Warrants a Left-Turn Lane
Four-Leg Intersection, Major-Road
Peak-Hour Volume (veh/hr/ln) that
Warrants a Left-Turn Lane
5 450 50
10 300 50
15 250 50
Section 5: Transportation Design Criteria
5.4 Intersection Design
5.4.4 Turn Lane Requirements
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20 200 50
25 200 50
30 150 50
35 150 50
40 150 50
45 150 <50
50 or More 100 <50
Notes:
[1] These guidelines apply where the major road is uncontrolled, and the minor -road approaches are stop- or yield-controlled. Both the
left-turn peak-hour volume and the major-road volume warrants should be met as shown in Figure 5.X.
[2] Major road volume shall be calculated as the total traffic volume from both approaches of the major roadway, divided by t he total
number of through lanes on those approaches.
Table 5.4-E: Left-Turn Warrants for Two-Lane Roadways [1]
Source: AASHTO A Policy on Geometric Design of Highways and Streets
Left-Turn Lane Peak-
Hour Volume (veh/hr)
Three-Leg Intersection, Major-Road Peak-
Hour Volume (veh/hr/ln) that Warrants a
Left-Turn Lane
Four-Leg Intersection, Major-Road Peak-
Hour Volume (veh/hr/ln) that Warrants a
Left-Turn Lane
5 200 150
10 100 50
15 100 50
20 or more 50 < 50
Notes:
[1] These guidelines apply where the major road is uncontrolled, and the minor-road approaches are stop- or yield-controlled. Both the left-
turn peak-hour volume and the major-road volume warrants should be met.
[2] Major road volume shall be calculated as the total traffic volume from both approaches of the major roadway, divided by t he total number
of through lanes on those approaches.
[3] Bypass lanes warrant analysis at three-leg rural intersections shall follow the TxDOT Roadway Design Manual.
Table 5.4-D: Left-Turn Warrants for Urban and Suburban Roadways
Left – Turn Lane
Peak Hour Volume
(vehicles per hour)
Three-Leg Intersection,
Arterial/Collector Volume
(vehicles per hour per lane)
that Warrants a Left-Turn Lane
Four-Leg Intersection,
Arterial/Collector Volume
(vehicles per hour per lane)
that Warrants a Left-Turn Lane
5 450 50
10 300 50
15 250 50
20 200 50
25 200 50
30 150 50
35 150 50
40 150 50
45 150 <50
Section 5: Transportation Design Criteria
5.4 Intersection Design
5.4.4 Turn Lane Requirements
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50 or More 100 <50
Figure 5.3 below guides the left-turn lane requirements design plan. Conditions for requesting a
left-turn lane include large truck volume, high crash history, limited sight distance, and significant
delay for motorists to make the turn, as determined by the City’s Engineer. Further discussion and
examples of left-turn lane guidance can be found in AASHTO's Policy on Geometric Design of
Highways and Streets.
Figure 5.3 Left-Turn Lane
B. Right-Turn Lane Warrants
When designing an intersection that provides direct or indirect access to the proposed
development, right-turn lanes should be provided along major arterial and collector roads at
driveways when the right turns are permitted and satisfy the following criteria. Table 5.4- GE below
provides criteria which warrant right-turn lanes. Figure 5.4 below provides guidance on right-turn
lane requirements.
Table 5.4- G: Right-Turn Warrants for Urban and Suburban Roadways
Roadway Classification Speed Limit (mph) Volume (Vehicles per Hour)
Arterial / Collector 45 or greater 50 or more
Arterial / Collector Less than 45 60 or more
Figure 5.4 Right-Turn Lane
Conditions for requesting an exclusive right-turn lane when right-turn traffic volume projections
Section 5: Transportation Design Criteria
5.4 Intersection Design
5.4.5 Intersection Detail for Collectors and Arterials
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are less than indicated in Table 5.4- GE, include the following, as determined by the City’s Engineer:
1. Large volume of truck traffic,
2. High crash history,
3. Roadways with limited sight distance, or
4. Heavier than normal peak flow movements on the main roadway.
C. Turn Lane Geometry
When a turn lane is required, Table 5.4- H F below shall be used as the minimum criteria for the
turn lane geometry. Additional consideration shall be given for unique traffic movements such as
excessive tractor trailer utilization, extended length transport vehicle movement, etc. See Section
5.4.5 see Section 5.4.5 below for additional geometry standards for Collectors and Arterials.
Table 5.4- HF: Minimum Turn Lane Geometry
Intersection Type
Lane
Width
(feet)
Minimum
Storage
Length
(feet)
Minimum Taper
(feet)
Additional
ROW
Required
(feet)
LEFT
TURN
RIGHT
TURN
Residential Collector 11 100 100 100 15
Major/Commercial/Industrial
Collector 11 150 100 150 15
Secondary Arterial 11 150 100 200 15
Primary Arterial 11 200 100 200 15
Notes:
[1] Required turn lane storage may be greater depending upon the TIA.
[2] The Pedestrian Path shall be taken into account for access across the median by utilizing a leave-out or ramp in
accordance with accessibility standards described in this manual.
[3] Cross slope of median openings or turn bays shall not be more than 2% or less than 1%.
[4] On TxDOT Roadways, TxDOT Roadway Design Manual standards shall supersede City of Denton Standards.
[5] Taper Radius shall be 200 feet minimum.
[6] Additional ROW required per turn lane bay, if ROW is not sufficient.
5.4.5 Intersection Detail for Collectors and Arterials
Figure 5.5 below provides median location details and specific turn lane radius requirements. Also refer to
median details shown in the City of Denton Standard Details.
Section 5: Transportation Design Criteria
5.4 Intersection Design
5.4.7 Intersection Spacing
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Figure 5.5 Intersection Detail for Collectors and Arterials
Notes:
1. For collector and arterial streets, A = 15 feet minimum.
2. Depending upon traffic flow requirements, the right turn may require a hooded right turn.
5.4.6 Intersection Spacing
Standards for intersection spacing are outlined below in Table 5.4- I. G.
Table 5.4-I: -G: Minimum Intersection Spacing 1
Roadway
Classification Alley Flag Drive Residential Collector Arterial
Alley 100 feet N/A 100 feet 100 feet N/A
Flag drive N/A N/A 75 feet 75 feet N/A
Residential 100 feet 75 feet 200 feet 2 200 feet 2 400 feet
Collector 100 feet 75 feet 200 feet 2 200 feet 2 400 feet
Arterial N/A N/A 400 feet 400 feet 1200 feet
Notes:
[1] Spacing will be measured between face of the curbs.
[2] 100-ft. minimum to the first intersection for entrances to subdivisions off of an arterial, where lots back up to the arterial.
5.4.7 Roundabouts
Roundabouts are circular intersections that create counter-clockwise traffic movements around a central
island, with entering traffic yielding to circulating traffic.
The design of a roundabout shall be in compliance with the Intersection Control Evaluation provided by the
FHWA. Normally, each roundabout will be unique in some way, as such a standard roundabout is not
included in this Manual. Also, the various analyses and design considerations involved in roundabout
design are beyond the scope of this Manual.
A. The following resources shall be used when designing a roundabout:
Section 5: Transportation Design Criteria
5.5 Auxiliary Roadway Design
5.5.2 Alleys
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1. TxDOT Roadway Design Manual
2.
3. NCHRP Report 1043: Guide for Roundabouts (2023)
2.
4. TxDOT Auxiliary Lane requirements for right turn lane
5.3. Federal Highway Administration Roundabouts, An Information Guide
6.4. Federal Highway Administration Roundabouts, Technical Summary
B. In addition to the resources provided above, the roundabout design shall include the following
design review process with the City’s Engineer and City Staff:
1. Have a Pre-Application Conference on the project, which will include a separate meeting with
the City’s Engineer for proposed roundabout design considerations;
2. Have a Traffic Impact Analysis (TIA) review meeting with the City’s Engineer. See section on
TIA requirements;
3. Develop Preliminary layout of roundabout considering TIA and Pre-Development meetings;
4. Preliminary Design review meeting with the City’s Engineer;
5. Develop roundabout design based up comments from the City’s Engineer; and
6. Submit roundabout design through the Development Review Process (DRP).
5.5 Auxiliary Roadway Design
5.5.1 Alleys
A. Alleys shall have at least two (2) direct access points to public streets and are subject to the block
length criteria included in this Manual.
B. Alleys shall be a minimum of 15 feet wide, with edges sloping towards the centerline at 3% slope.
C. No drainage infrastructure will be allowed within the alley ROW. Alleys shall be designed to convey
all runoff along the surface of the pavement.
D. Alleys that are intended to provide fire apparatus access must meet the design requirements of
Section 5.6.3-Fire Apparatus Access Roads Section 5.6.3-Fire Apparatus Access Roads of this
Manual.
E. Refer to City of Denton Standard Detail T103C for further details.
5.5.2 Drives
The design criteria for drives detailed in this section should be utilized in conjunction with the standards
outlined in DDC 8.3 (Lot Planning). The following standards generally apply to all developments. However,
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5.5 Auxiliary Roadway Design
5.5.2 Drives
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there may be unique situations for which these standards may be impractical. In these situations, the City’s
Engineer will work with the developer to develop a mutually agreeable solution. In the event that a mutually
agreeable solution is not reached, the developer may apply to the Planning and Zoning Commission for
consideration of the issue.
A. Drive Approach Standards
Table 5.5-A: Drive Approach Dimensions
Development Type 1 Drive Approach Widths Radius
MIN. WIDTH
(FEET)
MAX. WIDTH 2
(FEET) (FEET)
Residential – Single-family or Duplex 12 20 5 3
Residential – Multifamily 24 38 10 to 20
Commercial or Industrial 4 30 38 20 to 25
Notes:
[1] Driveways on TxDOT roadways - driveway width and curb radius shall meet TxDOT Roadway Design Manual
standards.
[2] Refer to Figures 5.6 through 5.10.
[3] If the drive approach is part of the fire apparatus access road, refer to Section 5.6.3 of this manual.
[42] Maximum drive approach width is a function of traffic volume.
[53] Add five (5) feet to maximum radius for significant truck traffic.
[64] For shared drive approaches, no lot shall contain less than nine (9) feet of the drive approach and driveway or
drive aisle (as may apply). Drive approach shall be centered on lot line, such that maximum drive approach
width equals 30 feet.
1. Residential
a. One (1) single-family or one (1) duplex residential lot accessing a collector may be
permitted to have one (1) full-width or circular drive approach (Figure 5.6 below), when
alleys are not practical.
b. Two (2) adjacent single-family or two (2) adjacent duplex residential lots accessing a
collector may be permitted to have one (1) shared full-width or circular drive approach,
when alleys are not practical.
c. Three (3) or more contiguous single-family or three (3) or more contiguous duplex
residential lots accessing a collector will be required to enter the collector by an alley,
flag drive, or residential street.
d. One (1) single-family or one (1) duplex residential lot accessing an arterial, will be
required to have an on-site facility, allowing entrance into the arterial in a forward
manner.
e. For homes with a 3-car garage or greater, where the garage door is street-facing and
less than 40 feet from the back of curb, the maximum drive approach width shall be 30
feet.
Section 5: Transportation Design Criteria
5.5 Auxiliary Roadway Design
5.5.2 Drives
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Figure 5.6 Residential Circular Drives
2. Commercial
a. All stop bar markings and stop signs when used shall be on private property, as well as
upstream of any pedestrian facility crossing the drive approach and/or drive aisle.
b. All signs and markings should be consistent with TMUTCD.
c. Drive approaches with significant truck traffic may install surmountable curb with
textured and colored pavement in the parkway, with a depth equal to or greater than
the drive approach pavement requirement.
d. Ingress/Egress Lanes
i. Single Lane Egress/Ingress (Figure 5.7) - The outbound (towards the street) lane
shall be a minimum of 12 feet wide; if the width of the driveway is greater than 30
feet, then the inbound (onto the site) lane shall be a minimum of 18 feet wide.
Figure 5.7 Drive Approach: Single Lane Egress/Ingress
ii. Dual Lane Egress, Single Lane Ingress (Figure 5.8) - The outbound lanes shall be 10
feet wide; if the width of the driveway is greater than 30 feet, then outbound lanes
shall remain 10 feet wide while the width of the inbound lane shall be increased.
Section 5: Transportation Design Criteria
5.5 Auxiliary Roadway Design
5.5.2 Drives
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Figure 5.8 Drive Approach – Dual Lane Egress, Single Lane Ingress
iii. Multiple Lane Egress/Ingress (Figure 5.9) - Only allowed when dual left-turn lanes
into the site or opposing street/driveway has two (2) or more lanes, of which two
(2) are designated as being through lanes.
a) Each of the two (2) outbound and inbound lanes shall be 10 to 12 feet wide.
b) Median shall accommodate any pedestrian facility across the drive approach
and/or drive aisle, as projected from both sides thereof.
Figure 5.9 Drive Approach – Multiple Lane Egress/Ingress
iv. Right-in or Right-out Egress/Ingress - The minimum width of the drive
approach/drive aisle prior to the island, each lane (inbound and outbound) at the
island, and the applicable radii shall be determined by the engineer of record,
based on expected vehicle type(s), as well as an auto-turn analysis provided to the
City’s Engineer for review and approval as part of the Civil Engineering Plan
submittal.
a) Median/island shall accommodate any pedestrian facility across the drive
approach and/or drive aisle as projected from both sides thereof.
b) For “one way in” or “one way out” driveways, the geometry shall be as shown
in Figure 5.10 below for the respective side.
c) Through a Design Deviation request, the minimum drive approach width may
be reduced based upon acceptable turning radius for emergency vehicles, and
determination that truck traffic requiring the larger width will not occur.
Section 5: Transportation Design Criteria
5.5 Auxiliary Roadway Design
5.5.2 Drives
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d) When the right in/right out drive approach is part of the fire apparatus access
road, the minimum width of each drive shall be 24 feet.
Figure 5.10 Drive Approach – Right in or Right out Egress/Ingress
v. With the exception of multi-lane egress/ingress (shown in Figure 5.9), drive
approaches with a median installed in lieu of the double-yellow marking, may
exceed the maximum drive approach width by the width of the median only.
v.vi. Right-in/right-out driveways along TxDOT frontage roads may be designed
without a porkchop unless the driveway is in close proximity to exit and entrance
ramps. A regular driveway approach with one-way signs is acceptable
B. Drive Approach Spacing
1. Same side of the street
Drive approach spacing shown in Table 5.5-B below applies to drive approaches on the same
side of the street, and is measured between the nearest edges of each drive approach, along
the back of curb, not including the radius.
Table 5.5-B: Minimum Drive Approach Spacing
Roadway Classification Min. Spacing 1 (feet)
Primary Arterial 200 2
Secondary Arterial 150 2
Major Collector/Collector 100 3
Residential Street 4 5010
Flag Drive 10
Alley 10
Notes:
[1] Driveways on TxDOT roadways must meet the minimum spacing in the TxDOT Access Management
Manual, Table 2‑2.
[2] A Mmaximum of two (2) drive approaches permitted. If a seco2nd point of access is required by
Ccity Ffire Code officialdivision, it must be remote, meaning driveways are spaced no less than half
the diagonal of the maximum overall dimension of the lot.
[32] If permitted; drive approaches are not permitted on arterial streets, unless otherwise allowed
according to Section 5.6 of this Manual.
Section 5: Transportation Design Criteria
5.5 Auxiliary Roadway Design
5.5.2 Drives
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[43] If permitted; refer to Section 5.6 of this Manual for permitted access.
[54] For a T-intersection on residential streets, the drive approach shall be offset farthest from the
intersection.
[6] Single-family driveways on residential streets require a minimum spacing of 10 ft.
2. Near Intersections
Drive Approach spacing shown in Table 5.5-C below applies to drive approaches near
intersections, andintersections and is measured between the face of the curb of the
intersecting street and the nearest edge (face of curb) of the drive approach not including
the drive approach radius; see Figure 5.11 below.
Figure 5.11 Drive Approach Spacing at Intersections
Table 5.5-C: Minimum Drive Approach Spacing at Intersections
Intersection Type Approaching the Intersection Departing the Intersection
Arterial - Arterial 1 150 feet on both streets 200 feet on both streets
Collector - Arterial 1 75 feet on collector, 150 feet on arterial 100 feet on collector, 200 feet on arterial
Collector - Collector 75 feet on both streets 100 feet on both streets
Residential - Arterial 1 50 feet on residential, 150 feet on arterial 50 feet on residential, 200 feet on arterial
Residential - Collector 50 feet on residential, 75 on feet collector 50 feet on residential, 100 feet on collector
Residential - Residential 2 50 feet on both streets 50 feet on both streets
Flag Drive - Collector 1 20 feet on flag drive, 75 feet on collector 20 feet on flag drive, 100 feet on collector
Flag Drive - Residential 1 20 feet on flag drive, 50 feet on residential 20 feet on flag drive, 50 feet on residential
Alley - Collector 1 20 feet on alley, 75 feet on collector 20 feet on alley, 100 feet on collector
Alley - Residential 1 20 feet on alley, 50 feet on residential 20 feet on alley, 50 feet on residential
Alley - Alley 10 feet on both alleys 10 feet on both alleys
Notes:
[1] If permitted by the City’s Engineer.
[2] Driveways across T-intersections on residential streets are exempt.
Section 5: Transportation Design Criteria
5.5 Auxiliary Roadway Design
5.5.2 Drives
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3. Offset and relative to median openings (See Figures 5.12 and 5.13 below)
a. For collector streets, drive approaches that do not align across the street from each
other must be offset by a minimum of 75 feet between nearest tangent-edge to nearest
tangent-edge.
b. For arterial streets without medians, drive approaches must align across the street from
each other, and must be approved by the City’s Engineer. When this is not physically
possible or practical as determined by the City’s Engineer, drive approaches that do not
align must be offset across the street from each other by a minimum of 150 feet
between nearest tangent-edge to nearest tangent-edge.
c. For arterial streets with medians, drive approaches must align with existing or proposed
median openings. Where this is not possible or practical as determined by the City ’s
Engineer, drive approaches must be placed as far away from the existing or proposed
median opening as is reasonably possible.
Figure 5.12 Drive Approach Near Turning Movements
Figure 5.13 Drive Approach Near Turning Movements
C. Drive Approach Grades
1. Minimum Drive Approach Slope:
Section 5: Transportation Design Criteria
5.5 Auxiliary Roadway Design
5.5.2 Drives
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The minimum drive approach slope shall be determined by:
S = (6 + [0.02 x W x 12]) / (W x 12) [Eqn. 5.2]
Where: W = the width of the parkway in feet as shown on the City of Denton
Standard Details.
2. Maximum Drive Approach Slope: Unless otherwise approved by the City’s Engineer through
a design deviation request (Section 8), the maximum drive approach slope shall be 12%.
3. Difference in Drive Approach Grade: Driveway profiles shall not have a grade difference
greater than 5%, without constructing a vertical curve. A minimum K-value of 4 is
recommended for driveways accommodating low ground clearance or long wheelbase
vehicles.
4. Sidewalks in Drive Approach: Maximum sidewalk cross slope within the limits of the drive
approach shall be 2%.
5. Sidewalk Easement Requirement: Where the parkway width is insufficient to provide
appropriate drive approach slope, a sidewalk easement will be required, equal to the balance
of the sidewalk width needed outside the ROW plus two (2) feet. The additional two (2) feet
requirement is for sidewalk installation and maintenance. The balance of the sidewalk width
needed is based upon using the minimum drive approach slope calculated in Section
5.5.2.C.1 above. See Figure 5.14 below as well as City of Denton Standard Details.
6. Driveway/Drive Aisle Consideration: The drive approach slope from the bottom of the gutter
to the nearest edge of the sidewalk (within the limits of the ROW) shall not exceed the
driveway/drive aisle slope beginning at the furthermost edge of the sidewalk. Also, it shall
not be less than the minimum slope, nor be greater than the maximum slope as noted herein.
Figure 5.14 Sidewalk Easement to meet Drive Approach Slope
D. Driveway Throat Length Requirements
1. Minimum throat length requirements are shown in Table 5.5-D below. Note that throat
length requirement applies to both edges of the drive approach.
2. All drive approaches that access an arterial shall be classified as a primary drive approach. If
no drive approaches access an arterial, then the drive approach expected to receive the most
traffic is considered to be the primary drive approach.
Section 5: Transportation Design Criteria
5.5 Auxiliary Roadway Design
5.5.2 Drives
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3. The throat length is measured between the first parking space or drive aisle and the curb
line, whichever is closer to the curb line.
4. Parking lots with 10 or less parking spaces may use a minimum throat length of 10 feet for
drive approaches accessing a residential or collector street.
4.5. For gated entries, a minimum storage of 100’ storag feete must be provided from the travel
lane face of the curb with an area for turnaround.
5.6. A Qqueuing analysis shall be required for gated entrances and drive-throughs.
Table 5.5-D: Minimum Throat Length
No. of Parking Spaces Min. Throat Length for
Primary Drive Aisle (feet)
Min. Throat Length for
Secondary Drive Aisle (feet)
0 to 100 20 20
101 to 250 40 20
251 to 500 60 40
501 to 1000 80 60
1001 and above Queuing Analysis Required Queuing Analysis Required
E. Driveway Separation
Driveways shall be separated in accordance with Table 5.5-B to ensure that all driveways are
separated by sufficient distance so as to avoid interfering with the safe movement of traffic. In
interpreting and applying the separation requirements, the following shall apply:
1. The separation requirements shall be determined in reference to any proposed or existing
driveways on or off the property. Where applied to a property, which is located adjacent to
an undeveloped tract, the separation requirements shall account for the placement of future
driveways on the adjacent undeveloped property.
2. The minimum separation specified may be reduced for currently developed property, if the
amount of street frontage for the property is insufficient to allow for one (1) driveway access
that would have the necessary separation from an existing driveway on adjacent property,
and joint access with adjacent properties is not physically possible, as determined by the
City’s Engineer. If a reduction in the minimum separation specified is allowed, the separation
shall be reduced only to the degree necessary to allow for the single driveway.
F. Corner Clearance Standards
Corner clearance standards shall be applied in accordance with AASHTO “Green book” to ensure
that the traffic movements from driveways do not unduly conflict with the movement of traffic on
intersecting public streets. In interpreting and applying the corner clearance standards, the
following shall apply:
1. A reduced requirement may only be used if absolutely necessary to provide driveway access
to property where no other means of access meeting the corner clearance requirement is
reasonably possible, and joint access with adjacent properties is not physically possible as
determined by the City’s Engineer. If a reduction in the minimum corner clearance specified
is allowed, the corner clearance shall be reduced only to the degree necessary to allow for
the single driveway.
Section 5: Transportation Design Criteria
5.5 Auxiliary Roadway Design
5.5.3 Cul-de-sacs
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2. The specified distances shall be measured at the ROW line from the edge of the driveway
nearest the intersecting street to the ROW line of the intersecting street. Where ROW corner
clips exist or are proposed, the specified distance shall be measured from the edge of the
driveway nearest the intersecting street and the end of the corner clip nearest to the subject
driveway.
G. Modifications to Existing Drives
Existing non-compliant drives may be modified to comply with criteria set forth in this Manual, but
may not be modified in a way that increases the non-compliance with this Manual.
H. TxDOT Drives
All drives connecting to TxDOT roadways shall meet all required TxDOT standards, in addition to
meeting City of Denton standards when applicable.
5.5.3 Cul-de-sacs
A. Geometrical Standards
1. Maximum length of a Cul-de-sac shall be 600 feet measured from the centerline of the
intersecting street to the Cul-de-sac radius point, and perpendicular to the intersecting street
centerline.
2. Minimum length of a Cul-de-sac shall meet Fire Code requirements.
3. Residential Cul-de-sacs shall not have more than 29 residential lots.
4. The center radius of the Cul-de-sac shall be a minimum of 50 feet for residential
developments, and 60 feet for commercial and industrial developments measured from the
center point to the face of curb or edge of pavement where there is no curb.
5. The Cul-de-sac return radius shall be 30 feet.
6. Cul-de-sac minimum street grades shall be as shown below in Figure 5.15 and Figure 5.16
below for downward gradient and upward gradient, respectively.
Section 5: Transportation Design Criteria
5.5 Auxiliary Roadway Design
5.5.3 Cul-de-sacs
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Figure 5.15 Cul-de-sac Minimum Slope - Downward Gradient
Figure 5.16 Cul-de-sac Minimum Slope - Upward Gradient
B. Offset Cul-de-sacs
1. Offset Cul-de-sacs shall have the same radius and return radius as the standard Cul-de-sac.
2. The length of the offset Cul-de-sac shall be measured from the centerline of the intersecting
street to the Cul-de-sac radius point, perpendicular to the intersecting street centerline.
Section 5: Transportation Design Criteria
5.5 Auxiliary Roadway Design
5.5.4 Hammerhead Turnarounds
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C. Temporary Turn-Around
1. A temporary turn-around shall be limited to approved phase developments where the street
will be extended in the future.
2. A temporary turn-around shall meet the requirements of a standard Cul-de-sac for radius
and return radius size.
3. The length of street associated with the turn-around shall not be any greater than 600 feet
nor less than Fire Code requirements.
4. If the length of street will be greater than 600 feet, then the next block length of street and
intersecting streets shall be constructed in order to provide looped traffic flow for emergency
vehicles.
5. The turn-around section shall be constructed to the same structural section as the street
section less curb and gutter requirements, unless drainage requirements warrant curb and
gutter.
5.5.4 Hammerhead Turnarounds
F. A hammerhead turnaround is a T-shaped roadway design provided at the end of a dead-end street
or fire lane to allow vehicles, especially emergency vehicles, to turn around efficiently. Hammerhead
turnarounds are typically used w
G. ere a full cul-de-sac is not feasible due to site constraints or where minimal right-of-way is available.
H. Design Requirements
A. The legs of the hammerhead (forming the “T” shape) should be at least 60 feet in length, measured
from the centerline of the intersecting roadway.
B. The turnaround must be constructed to support heavy vehicles and meet anyall width and corner
radius standards required for emergency access.
C. No parking or obstructions are allowed within the hammerhead area to ensure full access for
emergency vehicles.
Hammerhead turnarounds may also be used for temporary access when full cul-de-sacs
cannot be constructed, but permanent installations should meet all city standards for surface,
signage, and access restrictions.
Figure 5.17 Hammerhead Turnarounds
Section 5: Transportation Design Criteria
5.5 Auxiliary Roadway Design
5.5.5 Supplementary Design Elements
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Figure 5.17 Hammerhead Turnarounds
Design Requirements
Hammerhead turnarounds provide a safe and practical alternative to cul-de-sacs in constrained
residential developments, while maintaining compliance with fire and emergency vehicle
regulations.
5.5.5 Supplementary Design Elements
A. Signage and Sstriping
Signage and pavement markings shall be as shown in the Texas Manual on Uniform Traffic Control
Devices (TMUTCD).
New subdivisions must include STOP signs on minor street app
roaches and All-Way STOP control (AWSC) where long stretches of Residential, Collector,
and Arterial intersections. (Determined by the reviewer or City’s Engineer)
1. . The Ccity’s Traffic Engineer must approve AWSC signs.
2. Midblock crossings are discouraged; where it’s inevitable, it must have LED- Crosswalk Signs,
Ped warning, Ped crossing signs, Rectangular Rapid-Flashing Beacons (RRFBs), Pedestrian
Hybrid Beacons (PHBs), or other active crossing signs as directed by the City’s Traffic
Eengineer.
3. Crosswalk Markings - Continental style – Two (2) feet’ wide by , 10' feet long white
thermoplastic
a. Crosswalks shall only be installed if there are Barrier-Free Ramps (BFRs) on both ends
of the road.
b. Crosswalks are required only on Collectors and above, not on residential, local streets,
or alleys.
6.4. ‘STOP’ Bars -– 24 inches" white thermoplastic located 2 inches' from the crosswalk or aligned
with ‘STOP’ signs.
B. On-street Parking
Consistent with the requirements of Public Rights of Way Accessibility Guidelines (PROWAG), the
following Americans with Disabilities Act (ADA) on-street parking requirements shall be followed:
1. General
a. On-street parking is permitted for residential and residential collector streets, unless
prohibited by the City’s Engineer.
b. On-street parking should be parallel, while angled and perpendicular parking requires
approval from the City’s Engineer.
a.
b.c. On-street parking for proposed commercial/industrial collectors or arterials is not
allowed. Where on-street parking is designated, one (1) on-street parking space for
each single-family unit on a block is required on the frontage street within that block.
c.d. Areas in front of a driveway, within five (5) feet of a driveway, within 20 feet of a street
intersection, or within 15 feet of a fire hydrant shall not be counted toward the required
Section 5: Transportation Design Criteria
5.5 Auxiliary Roadway Design
5.5.5 Supplementary Design Elements
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on-street parking.
2. Parallel Parking
a. For parallel parking spaces where the adjacent sidewalk or available ROW is more than
14 feet wide, an access aisle must be provided at street level for the entire length of
each accessible parallel parking space.
b. The access aisle must be a minimum of five (5) feet wide and connect to a pedestrian
access route.
c. The access aisle must not encroach on the vehicular travel lane and must comply with
the technical requirements for surfaces.
d. In alterations where the street or sidewalk adjacent to the parking spaces is not altered,
an access aisle is not required, provided the parking spaces are located at the end of
the block face.
e. Where the adjacent sidewalk or available ROW is less than or equal to 14 feet wide, an
access aisle is not required, but accessible parallel parking spaces must be located at
the end of the block face.
Figure 5.187 shows the acceptable parking configuration for on-street parallel parking.
Figure 5.18 Parallel Parking
3. Perpendicular and Angled Parking
a. For perpendicular and angled parking spaces, an access aisle must be provided at street
level for the entire length of each accessible perpendicular or angled parking space.
b. The access aisle must be a minimum of eight (8) feet wide to accommodate vans with
lifts and connect to a pedestrian access route.
c. Two (2) accessible parking spaces are permitted to share a common access aisle.
d. The access aisle must be marked to discourage parking in the aisle and comply with the
technical requirements for surfaces.
Figures 5.198 through 5.221 show the acceptable parking configurations for on-street
angled parking.
Section 5: Transportation Design Criteria
5.5 Auxiliary Roadway Design
5.5.5 Supplementary Design Elements
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Figure 5.19 Angled Parking – 30 degrees
Figure 5.20 Angled Parking - 45 degrees
Figure 5.21 Angled Parking - 60 degrees
Section 5: Transportation Design Criteria
5.5 Auxiliary Roadway Design
5.5.5 Supplementary Design Elements
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Figure 5.22 Angled Parking - 90 degrees
4. Curb Ramps and Blended Transitions
a. Curb ramps and blended transitions must connect the access aisle serving each
accessible on-street parking space to the pedestrian access route.
b. Curb ramps are not permitted within the access aisle.
c. Parking spaces at the end of block face can be served by curb ramps or blended
transitions at the pedestrian street crossing.
d. Detectable warning surfaces are not required on curb ramps and blended transitions
that connect the access aisle to the sidewalk, including where the sidewalk is at the same
level as the parking spaces, unless the curb ramps and blended transitions also serve
pedestrian street crossings.
5. Other
a. Wheel stops will be required to prevent vehicle overhang into adjacent property, ROW,
structures, landscaping or sidewalk (applicable to ‘**’ shown on above figures).
b. Parking spaces may be reduced to 16.5 feet in length if a two (2) feet overhang is
provided.
c. All standard parking space striping shall be white in color.
d. On-street motorcycle parking space is half the size of a vehicle parking space.
C. Median Openings
Median openings for collectors and arterials shall be as designated by the City’s Engineer. Median
opening allowance shall primarily consider the safety and effective flow of traffic within the collector
or arterial street, then secondarily consider the effective movement of traffic to and from the
development. Whether a median opening is allowed will solely be up to the City’s Engineer.
When a development is allowed to have a median opening, it shall be provided in accordance with
the following criteria:
1. The width of a median opening shall be 60 feet.
2. Median openings shall center on the intersecting drive.
3. Median openings shall be a minimum of 400 feet apart, measured from nose-to-nose of
medians.
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5.5 Auxiliary Roadway Design
5.5.5 Supplementary Design Elements
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4. Whenever a median opening is constructed, the associated left-turn lane serving the
development must be constructed at the same time. In the event that there is an existing
intersecting street on the opposite side of the street, the new development constructing the
median opening shall be required to install both left-turn lanes.
5. Patterned and colored median noses shall be constructed as shown on the City of Denton
Standard Details.
5.6. For any proposed median opening on TxDOT-maintained facilities, the standards outlined in
the TxDOT Roadway Design Manual shall be followed.
D. Traffic Calming
Traffic calming with respect to speed-control devices are not permitted on public ROW. Speed humps on
private property are prohibited unless approved by City Fire Code official, and shall comply with IFC
standards.
Appropriate signage and pavement markings are to be provided along with all traffic calming devices.
Additional ROW may need to be dedicated in order to accomplish adequate traffic calming.
A separate permit is required for the installation of speed control devices located in a fire lane. These devices
shall be constructed of durable rubberized material, molded plastic or of concrete.
1. General Policy
a. Traffic calming measures intended to control vehicle speeds within the public right-of-
way (ROW) are generally not permitted.
b. Exceptions may be considered in critical areas where documented overspeeding
presents a safety hazard - —such as in front of schools, hospitals, parks, or other
pedestrian-sensitive environments.
c. Any installation within the public ROW must be supported by an engineering study that
documents operating speeds exceeding the posted limit and must receive approval by
the City Fire Code Official, ensuring compliance with the most current provisions of the
International Fire Code (IFC) adopted by the City.
2. Prohibited vs. Conditional Devices
a. Prohibited Devices:
Speed humps, bumps, and other similar vertical deflection devices are prohibited
on both public ROW and private property fire lanesfire apparatus access roads.
i.
These devices have been shown to delay emergency response times by
approximately 10 seconds per device and have been associated with damage to
fire and EMS vehicle frames as well as injuries to emergency personnel during
response operations. For these reasons, they are not permitted within the City.
b. Conditional Devices:
i. Speed cushions or segmented devices designed to allow emergency vehicle
clearance may be considered on private property only. These devices require City
Fire Code Official approval and must conform to current IFC standards and
applicable AASHTO/ITE traffic calming guidance.
ii. Horizontal traffic calming devices (including but not limited to chokers, chicanes,
traffic circles, and similar geometric modifications) may be considered on a case -
Section 5: Transportation Design Criteria
5.6 Access Management
5.6.2 Purpose and Goals
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by-case basis within both public ROW and private property; however, their
implementation must be reviewed and approved by both the City ’s Engineer and
the City Fire DepartmentCode Official to verify that such devices do not impede
emergency vehicle access, turning radii, or overall response times.
3. Design & Installation Standards
a. All traffic calming devices must include signage and pavement markings in compliance
with the most recent MUTCD (TexasT MUTCD edition, where applicable).
b. Additional Right‑of‑WayROW dedication may be required to accommodate traffic
calming devices while maintaining minimum lane widths, drainage, and pedestrian or
/bicycle access.
c. Devices must be constructed of durable materials (e.g., pre‑molded rubber, modular
plastic, or reinforced concrete) to ensure long‑term performance and maintain
emergency response accessibility.
4. Permitting Requirements
A separate permit is required to install any speed control device within a designated fire
lanefire apparatus access road.
5.6 Access Management
5.6.1 Purpose and Goals
The purpose of the access management plan is to promote the health, safety, and general welfare of the
present and future residents of the city through managing traffic flow and promoting traffic safety.
In planning and designing access for proposed developments, the following documents should be utilized
in conjunction with this section:
A. DDC Section 7.8.9 – Driveways and Access
B. DDC Section 7.8.10 – Cross-Access Between Abutting Developments
C. TxDOT Access Management Manual (if the proposed access is onconnects TxDOT-maintained
facilities)
D. TxDOT Roadway Design Manual (if the proposed access is onconnects TxDOT-maintained facilities)
These standards collectively ensure safe, efficient, and coordinated access within the Ccity’s roadway
network.
5.6.2 Access Standards
A. Compliance
1. No person shall construct, reconstruct, replace, relocate, alter, enlarge, improve or perform
any work on or make use of any driveway for any property within the City or its extraterritorial
jurisdiction, except in accordance with the Access Management standards provided in this
Manual or the TxDOT Access Management Manual, when applicable.
Section 5: Transportation Design Criteria
5.6 Access Management
5.6.2 Access Standards
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2. All driveways shall be designed, installed, located, and constructed in accordance with the
approved specifications, plans, conditions, and requirements of the permit issued for the
property, and the requirements of this Manual.
3. No certificate of occupancy shall be issued for any building on any property for which a
permit is required, until the construction, improvements, alterations or other work covered
by the permit is completed in accordance with the permit issued, the requirements of this
Manual, or the provisions of any other applicable ordinance.
4. Where no building permit was required in connection with the requested permit, no driveway
on the property for which the permit was issued shall be used until and unless the work is
completed in accordance with the permit, and this Manual.
B. Access to Freeways
Access to freeways shall only be provided at entrance ramps. Access to frontage roads may be
provided in accordance with the standards for access to arterial streets set forth in this Manual, with
the following exceptions:
No access is allowed in areas where TxDOT owns the Control of Access. Such Control of Access
may be found on current TxDOT ROW maps.
No access is allowed within a paved gore area or 250 feet past painted gore of an exit ramp.
Similarly, no access is allowed within a paved gore area or 200 feet upstream of the painted gore
of an entrance ramp.
Direct access from private property to freeway main lanes is prohibited. A; access is provided
exclusively at designated interchanges and ramps. Access to adjacent frontage roads must comply
with the TxDOT Access Management Manual and are , subject to the following provisions:
1. Control of Access:
Access is prohibited in areas where the Texas Department of Transportation (TxDOT) has
established Control of Access.
Control of Access areas are documented on current TxDOT right-of-way (ROW) maps.
2. Direct Ramp Access:
a. Ramps with Frontage Roads: Direct access from adjacent properties or streets is strictly
prohibited for the entire length of the ramp.
b. Interstate Ramps without Frontage Roads or Interstate Interchange Connectors: Direct
access is prohibited along the full length of the ramp or connector in accordance with
23 CFR 625.3 and 625.4.
c. Non-Interstate Facilities without Frontage Roads: Direct access is strongly discouraged.
If allowed, the location must be determined based on spacing criteria and procedures
outlined in this Manual and the TxDOT Access Management Manual.
3. Frontage Road Considerations:
Direct access to frontage roads is prohibited in the vicinity of ramp connections to ensure
safe merging, weaving, and adequate acceleration and deceleration of vehicles.
4. Ramp Proximity Restrictions:
a. Exit Ramps: No access shall be permitted within the paved gore area or within 250 feet
downstream of the painted gore of an exit ramp.
Section 5: Transportation Design Criteria
5.6 Access Management
5.6.2 Access Standards
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b. Entrance Ramps: No access shall be permitted within the paved gore area or within 200
feet upstream of the painted gore of an entrance ramp.
c. For further guidance, refer to the TxDOT Roadway Design Manual.
5. Design Considerations:
The spacing of interchanges and ramps shall provide adequate distance for entering and
exiting vehicles to safely accelerate, decelerate, and weave, consistent with TxDOT design
standards.
C. Access to Arterial Streets
Access to an arterial street shall not be permitted unless there is no other reasonable means of
providing safe access to the property. Unless designated as a freeway, all TxDOT Highways shall
be considered arterials. Additionally, the geometric, hydraulic, and pavement designs of all access
driveways to TxDOT roadways must be reviewed by TxDOT to ensure compliance with their
standards.
1. No development shall be allowed access to an arterial street if property excluded from the
development could have been used to provide reasonable access to a lesser classified street,
or if the property has been previously subdivided in violation of state law or the DDC and if
access could have been provided to a lesser street except for such unapproved subdivision
of the property.
2. Existing commercial or industrial lots created prior to adoption of the DDC by legal
subdivision procedures with exclusive frontage on an arterial street may take access to the
arterial in accordance with the access standards in this Manual.
3. Existing single-family and duplex lots created prior to adoption of the DDC by legal
subdivision procedures with exclusive frontage on an arterial street may be developed with
a circular drive. Such drives shall be designed and constructed in accordance with standards
for circular drives provided in this Manual.
4. When drives access to an arterial street is the only reasonable means of providing safe and
adequate access to the property as determined by the City’s Engineer, the drive design,
number of drives, location and construction shall be in accordance with this Manual.
5. Drives on an arterial shall align with existing median openings, other driveways, and "T"
intersections, or be offset in accordance with this Manual.
D. Access to Collector Streets
1. Access to collector streets for commercial, office, or industrial development is required and
shall be designed and constructed in accordance with the standards provided in this Manual.
2. Single-family or duplex lots shall not be designed such that there is no other means of access
other than a collector street.
3. Existing single-family and duplex lots developed prior to approval of the DDC with exclusive
frontage on a collector street and no alley may be developed with a circular drive. Such
drives shall be designed and constructed in accordance with the standards for circular drives
provided in this Manual.
4. Drives on a collector street shall align with existing driveways and 'T' intersections on the
Section 5: Transportation Design Criteria
5.6 Access Management
5.6.3 Fire Apparatus Access Roads
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opposite side of the street, or shall be offset in accordance with this Manual.
5.4.
5.6.3 Fire Apparatus Access Roads
A. Design Standards
1. Prior to construction, the design of the fire lane shall be submitted to the Fire officials for
review and approval.
2. Fire apparatus roads shall have an unobstructed width of not less than 24 feet and
unobstructed vertical clearance of not less than 14 feet. These are minimums and may be
increased where they are inadequate for fire or rescue operations.
3. Fire lanes shall be constructed to meet the City of Denton's Engineering Standards for a
concrete pavement cross-section of a residential street.
4. Fire lane grade shall be no greater than 10%.
5. Fire lanes shall be located so that access to all points of the building served is a maximum of
150 feet, as measured by hose lay. This can be increased to 300 feet, for a building fully
equipped with an approved automatic fire suppression system and with the fire code official’s
approval.
The design of all fire apparatus access roads and fire lanes shall be submitted to the Fire Department
for
review and shall approval prior to construction. No fire lane shallnot be constructed without prior
authorization from the City Fire Code Official.
1. Fire apparatus access roads shall be constructed in accordance with the City of Denton
standards for the concrete pavement cross-section of a residential street.
2. They shall be designed for all-weather use and capable of supporting fire apparatus with a
load rating of up to 75,000 pounds.
6.3. Width, and Clearance, and Setback
a. MMinimum unobstructed width of : 24 feet for buildings up to 30 feet in height, and 26
feet for buildings over 30 feet in height.
b. Width increases to 26 feet for buildings over 30 feet in height.
c.b. MiMinimum vertical clearance of 1: 14 feet.
7. SetbackThese minimums may be increased where fire or rescue operations require additional
clearance.
8. Setback from Building:
d.c. from the building face shall be a minimumMinimum of 15 feet and , maximum of 30
feet from the building face.
9.4. Fire apparatus access roads must have a Turning Radius:minimum inside turning radius of 25
feet, and a minimum outside turning radius of 45 feet.
e. Minimum inside turning radius: 25 feet.
f. Exceptions:
Section 5: Transportation Design Criteria
5.6 Access Management
5.6.3 Fire Apparatus Access Roads
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a. Driveways less than 24 feet wide may have a : minimum 28 feet inside turning radius of
28 feet.
b. Driveways wider than 26 feet may have a : minimum 20 feet inside turning radius of 20
feet.
a. Minimum outside turning radius: 45 feet.
10. Construction Standards
b. Fire lanes shall be constructed in accordance with the City of Denton Engineering
Standards for the concrete pavement cross-section of a residential street.
c. All fire lanes shall be designed for all-weather use and capable of supporting fire
apparatus with a load rating of up to 75,000 pounds.
11. Grade
12.5. Maximum grade for fire lanes apparatus access roads shall not exceed 10%.
13.6. Proximity to Buildings
Fire lanes apparatus access roads shall be located so that all parts of the building are
accessible within 150 feet, measured along the hose lay from the lane.
For buildings fully equipped with an approved automatic fire suppression system, this
distance may be increased to 300 feet upon approval of the City Fire Code Official.
14. Dead-End Lanes:
15. Mmust provide an IFC-approved turnaround if the dead-end exceeds 150 feet in length (IFC
Appendix D).
16.7. Refer to Sections 5.5.3 and 5.5.4 of this manual for further details regarding turnarounds.
17. Traffic ControlCalming:
18. - No speed bumps or similar traffic control calming devices shall be installedare permitted
in fire lanes apparatus access roads (IFC 503.4.1).
19.8.
B. Modification of Existing Fire LanesApparatus Access Roads
Modification of existing fire apparatus access roadslanes MUST be approved by the Fire Marshal's
Office.
C. Turning Radius
A 24-ft. wide fire lane will require a minimum of a 25-ft. inside turning radius or as approved by a
Fire Code Official.
D.C. Marking
1. Striping
Fire apparatus access roads shall be marked by painting 6-in. wide red traffic lines at the its
boundaries of the fire lane, as indicated on the plat. The words "NO PARKING FIRE LANE" or
"FIRE LANE NO PARKING" shall be four (4) inches high.
2. Signage
Section 5: Transportation Design Criteria
5.7 Bike and Pedestrian Facility Design
5.7.3 Mobility Plan Component
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Signs shall read "NO PARKING FIRE LANE" or "FIRE LANE NO PARKING" and shall be 12 -in.
wide and 18-in. high. Signs shall be painted on a white background with letters and borders
in red, using not less than 2-in. high lettering. Signs shall be permanently affixed to a
stationary post, and the bottom of the sign shall be six (6) feet and six (6) inches or 6'-6"
above finished grade. Signs shall not be spaced more than 50 feet apart. Signs may be
installed on permanent buildings or walls, as approved by the Fire Marshal.
5.7 Bike and Pedestrian Facility Design
The user should be aware of and utilize the DDC Section 7.8.11 Pedestrian and Bicycle Circulation, in
conjunction with this section for the design of bike and pedestrian facilities.
5.7.1 Mobility Plan Component
The City of Denton Mobility Plan includes a pedestrian and bicycle component, which should be reviewed,
relative to any proposed transportation improvement.
It should be noted that the City of Denton Mobility Plan is a living document and is periodically updated to
reflect the changes in the characteristics of anticipated traffic flow within the City.
5.7.2 Accessibility Standards
The City of Denton considers sidewalks to be accessible routes according to Section 4.3 of Texas
Accessibility Standards (TAS) and considers a public sidewalk a “facility”. Sidewalks, landings, ramps, and
flares shall comply with the most recently adopted TAS, ADA, PROWAG, and FHWA standards. Also,
sidewalks, landings, ramps, and flares are subject to the requirements of the Texas Department of Licensing
and Registration (TDLR) for inspection purposes. Prior to construction of sidewalks, the Engineer of Record
must show proof of TDLR review and approval for accessibility, if the total cost of the public improvements
will exceed $50,000.00. Compliance with the regulations shall be the responsibility of the Engineer of Record
for the project. Refer to the City of Denton Standard Details for additional requirements.
5.7.3 Geometric Standards
Table 5.7-A shows the standard width of sidewalks and bike lanes for the various roadway classifications.
Refer to the City of Denton Standard Details for the locations of sidewalks and bike lanes within the street
ROW. The Denton Mobility Plan should be reviewed for any planned bicycle and pedestrian facilities that
may exceed those called for by the standard details. Any portion of the proposed facility extending past the
ROW shall be contained within a pedestrian access easement. The recorded easement shall extend two (2)
feet beyond the edge of the facility.
Table 5.7-A: Bike and Sidewalk Requirements
Roadway Classification Min. Sidewalk Width 1 Min. Bike Lane Width 1
Freeway N/A
Arterials – Primary and Secondary 5 10
Major Collector 8 10
Collector – Commercial and Residential 85 10
Local – Residential 5 N/A
Section 5: Transportation Design Criteria
5.7 Bike and Pedestrian Facility Design
5.7.4 Intersection
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Local – Rural N/A N/A
Local – Alley N/A N/A
Notes:
[1] Refer to the City of Denton Standard Details street cross-sections for specific bike and pedestrian recommendations. A minimum 5-ft.
wide sidewalk on one side of the street, and a 10-ft. wide bicycle/pedestrian facility on the other side of street will be required.
[2] Sidewalks must be at least 6 inches away from the ROW line.
[3] Sidewalks must have green space/parkway between sidewalk and street curb per Ccity Standard Details.
[4] If sidewalks are provided at the back of the curb, then the minimum width must be 6 feet’.
[5] Inlet covers cannot be part of the sidewalk.
[6] Existing sidewalks that do not comply with, even in good condition and ADA and City/Mobility Plan standards should be upgraded -
compliant, must be widened to meet current Ccity//Momobility Pplan and ADA requirementsstandards.
[7] For sidewalks or other pedestrian facilities proposed in a TxDOT ROWright-of-way, a TxDOT permit will be required to do any work.
A. On Bridges
Sidewalks on bridges shall be a minimum width of six (6) feet or wider, as required by the street
classification. All street bridges shall have sidewalks on both sides of the bridge. Dependent upon
vehicular and pedestrian traffic considerations, a parapet wall may be required to separate the
sidewalk from the travel lane. Parapet walls shall be constructed to TxDOT standards. A pedestrian
bridge rail shall be constructed on the outside of the bridge to protect sidewalk traffic. Both bridge
rails and parapet walls shall meet accessibility standards.
B. On Drainage Crossings
Sidewalk at drainage crossings shall be a minimum width of six (6) feet or wider as required by the
street classification. Sidewalk railing shall be provided to protect the sidewalk traffic from the
outside edge of the drainage crossing. Dependent upon vehicular and pedestrian traffic
considerations, a parapet wall may be required to separate the sidewalk from the travel lane.
Parapet walls shall be constructed to TxDOT standards. Railing and parapet walls shall meet
accessibility standards.
C. Adjacent to Screen Walls
A minimum additional sidewalk width of two (2) feet shall be required beyond the standard width
of sidewalk, for sidewalks adjacent to screen walls.
D. Adjacent to Retaining Walls
A minimum greenspace width of five (5) feet between the sidewalk and the edge of a retaining wall
shall be required, for sidewalks adjacent to retaining walls.
5.7.4 Intersection
A. Curb Ramps
The continuation of accessible routes through intersections shall use approved curb ramps that
meet accessibility standards. Refer to the City of Denton Standard Details for curb ramps at
intersections. Crosswalks through the intersections shall meet accessibility standards.
The following provisions further define requirements for sidewalk connections, proposed barrier-
free ramps (BFRs), and receiving barrier-free rampsBFRs to ensure continuity, safety, and full
accessibility throughout the intersection.
1. Sidewalk Connections: Sidewalks connecting to existing barrier-free ramps (BFRs) at
intersections must be fully ADA-compliant.
2. Proposed Barrier-Free Ramps: Proposed BFRs at project corners must be aligned with
existing or planned BFRs on the opposite corners. Plans shall illustrate the full intersection
Section 5: Transportation Design Criteria
5.7 Bike and Pedestrian Facility Design
5.7.6 Signage and Pavement Markings
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layout, including all ramps and crosswalks.
Receiving Barrier-Free Ramps: For safety, accessibility, and route continuity, aA receiving BFR
is required in accordance with PROWAG (Public Rights-of-Way Accessibility Guidelines)
standards for all new construction and alterations to existing facilities. If no receiving ramp
exists on the opposite side of the intersection, a new receiving ramp with an appropriate
landing must be constructed, regardless of whether a sidewalk is present. Any exceptions
from this requirement must be approved by the City’s Engineer.
3.
B. Bike Lanes
Bike lanes at intersections shall consider other traffic movements and facilities such as turn lane
movements, transit facilities, parking, and stop bar locations. The current Urban Intersection Design
Guide by TxDOT can be used for bike lane design at intersections. The bike lane design at
intersections requires the approval of the City’s Engineer.
5.7.5 Signage and Pavement Markings
Signage and pavement markings shall be as shown on the TMUTCD Marking & Sign Drawings, and in
accordance with the accessibility standards.
A. Crosswalks
Continental type-high visibility crosswalk markings are to be provided in all uncontrolled street
crossings, school crossings, downtown areas, or as directed by the City’s Engineer.
B. Bike Lane
Traffic control devices such as vertical flex posts, green pavement markings, and wayfinding signage
may be required to enhance the proposed bicycle facility, as directed by the City’s Engineer. For
additional guidance, refer to Section 5.5.5.-A of this manual.
5.7.6 Amenities
A. Bike Parking
1. Refer to Bicycle Parking Guideline 2nd Edition by the Association of Pedestrian and Bicycle
Professionals (APBP) for general guidelines and resources.
2. All bicycle parking facilities/devices shall be constructed to meet commercial grade structural
standards.
3. Location Standard:
a. Bicycle parking must be on the same lot as the princip ale use.
b. Bicycle parking must be located in highly visible and well-lit areas.
c. Bicycle parking must not interfere with accessible paths of travel or accessible parking
as required by the accessibility standards.
d. Bicycle parking must be located within 50 feet of a main building entrance. In multiple
building locations, bicycle parking must be distributed in a manner that serves all
entrances.
4. Layout and Design:
Section 5: Transportation Design Criteria
5.7 Bike and Pedestrian Facility Design
5.7.6 Amenities
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a. Bicycle rack design:
i. Support the bicycle in at least two (2) places.
ii. Enable the frame and at least one (1) wheel to be secured.
iii. Designed to accommodate “U” shape locking devices.
iv. Installed to the manufacturer’s specifications.
v. Each bike rack must be designed to accommodate at least two (2) bikes.
vi. Each bike rack space should providebe a minimum of two (2) feet in width and six
(6) feet in length.
b. Bicycle Parking Space
i. Concrete pad built to City of Denton sidewalk standards.
ii. Must provide clearance of at least two (2) feet from closest wall.
iii. Must provide clearance of at least three (3) feet between bike racks.
iv. Must not interfere with pedestrian pathway.
A 4-foot aisle is needed behind or beside bike racks for comfortable parking and removal, especially
in multi-rack setupsIn addition to selecting an appropriate bicycle rack type, the overall layout of
bicycle parking areas shall be designed to ensure safe, efficient, and accessible use. Minimum
recommended dimensions for bicycle rack areas are provided in the APBP Bicycle Parking
Guidelines, as shown in Figure 5.23. (see Figure 5.23). For larger bicycle parking areas with high
turnover rates, multiple access points are recommended to facilitate user circulation and reduce
congestion. Where feasible, bicycle parking areas should be oriented and designed to provide
protection from weather elements, enhancing both usability and longevity of the racks.
B. Benches
All benches shall be constructed to meet commercial- grade structural standards. Benches shall be
secured to prevent displacement. Benches shall not project into any accessible route or alter an
accessible route such that it will not meet the accessible route standards.
In addition to selecting an appropriate bicycle rack type, the overall layout of bicycle parking areas
shall be designed to ensure safe, efficient, and accessible use. Minimum recommended dimensions
for bicycle rack areas are provided in the APBP Bicycle Parking Guidelines (see Figure 5.23). For
larger bicycle parking areas with high turnover rates, multiple access points are recommended to
facilitate user circulation and reduce congestion. Where feasible, bicycle parking areas should be
oriented and designed to provide protection from weather elements, enhancing both usability and
longevity of the racks.
Section 5: Transportation Design Criteria
5.8 Transit Facility Design
5.8.1 General
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Figure 5.23 Illustration. APBP-recommended design dimensions for bicycle rack areas.
C. Lighting and Enclosures
Lighting standards and above-ground enclosures shall not extend into any accessible route or alter
an accessible route such that it will not meet the accessible route standards.
Figure 5.23 APBP-recommended design dimensions for bicycle rack areasFigure 5.23 Illustration
5.8 Transit Facility Design
5.8.1 General
Bus stops shall meet at a minimum the design standards of the Denton County Transit Authority (DCTA),
and the accessibility standards of TAS, PROWAG, and ADA. Figure 5.242 show a general layout of a bus stop
Section 5: Transportation Design Criteria
5.8 Transit Facility Design
5.8.2 Bus Stop Placement
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at an intersection. Bus stops shall be located on the departing side of a street intersection. The use of a pull-
out lane may be considered where the specific site conditions warrant such an arrangement. The
determination of the appropriateness of a pull -out lane shall rest with the City’s Engineer.
Figure 5.24 Standard Bus Stop Location at Unsignalized Intersection
Note: For signalized intersections an Approach Side Bus Stop is preferred
5.8.2 Bus Stop Placement
Bus stop placement should consider the need for the bus stop, traffic operation concerns, and passenger
accessibility. A bus stop should be placed within an area that allows bus stop amenities to be located in the
public ROW and where the ingress and egress of the bus does not overly impede the flow of traffic. The
warrant for a bus stop shall be as required by the City of Denton in conjunction with DCTA. Elements to
consider for bus stop placement include the following:
A. ADA and PROWAG compliance of all elements, including pedestrian routes, shelters, signing, etc .
B. Within Public ROW, or a dedicated access easement.
C. Proximity to major trip generators such as malls, student housing areas, retail commercial zones,
park and rides, destination areas, etc.
D. Pedestrian facilities such as sidewalks or multi-use paths, marked cross walks, space provisions for
accessibility standards, and curb ramps should be available at the location for a proposed bus stop.
E. Convenient passenger transfers to other routes.
F. Open and visible location for personal security and passenger visibility.
G. Acceptable street illumination or proposed street illumination with placement.
H. Ability to have restrictive parking in bus zone.
I. Adequate space for bus zone.
Section 5: Transportation Design Criteria
5.9 Traffic Impact Analysis Guidelines
5.9.1 Bus Stop Amenities
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J. Gentle street grades at bus zone.
K. Return to traffic without overly hindering traffic flow.
L. No interference from driveways.
5.8.3 Bus Stop Amenities
The following are bus stop amenities that shall be considered during the process of design:
A. Accessibility compliant loading area. All bus stops shall have accessibility compliant loading and
offloading area. This area shall be integral to the sidewalk pathway, bench area, and shelter area, if
provided. The loading area shall be constructed of reinforced concrete with the same thickness as
the adjacent sidewalk.
B. Bench and trash receptacle may be warranted based upon Table 5.8-A. Bench and trash receptacle
type and installation shall be as required by the City of Denton.
C. A shelter may be warranted based upon Table 5.8-A The shelter type and installation shall be as
required by the City of Denton and DCTA. Shelters shall provide space to meet accessibility
standards.
D. Illumination shall be provided if illumination is not provided at the street corner adjacent to the bus
stop, or if in the opinion of the City’s Engineer the existing illumination is inadequate.
E. Bus stops that accumulate 10 points or more may be considered for shelter placement. Bus stops
that accumulate six (6) points or greater may warrant a bench and trash receptacle.
Table 5.8-A: Bus Stop Amenities Warrant
Points Condition
6 points 25 people per day boarding
4 points Special needs, i.e., Senior Center, Medical Complex, libraries, high accessibility
standard usage such as group residences
4 points High use location, i.e., Student housing area, schools, hospitals, mall
2 points Request for improvements by citizens, i.e., multiple requests over a one-year time
6 points 15 people per day or greater boarding
4 points Adjacent to an arterial roadway
5.8.4 Bus Stop Signage and Markings
Bus stop signage and markings shall be according to the City of Denton and DCTA. Signage shall include a
“No Parking Zone” sign and a DCTA bus stop sign.
5.9 Traffic Impact Analysis Guidelines
5.9.1 General
The purpose of the traffic impact analysis (TIA) is to assess the impacts of development on the existing
roadway system within the study area of the development and to assess the traffic flow needs within the
development. The thoroughfare component of the Mobility Plan and the City of Denton traffic model
Section 5: Transportation Design Criteria
5.9 Traffic Impact Analysis Guidelines
5.9.3 Preliminary Trip Generation Assessment
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establishes the base conditions for assessing the impacts. The current traffic model and the assessment is
based on a Level of Service D according to the current Highway Capacity Manual. The TIA shall be signed
and sealed by a licensed PE in a PE Licensed by the State of Texas, and shall be valid for a period of 3 years,
unless there is a significant change in the plans or surrounding conditions, as determined by City’s Engineer.
5.9.2 Preliminary Trip Generation Assessment
All developments are required to prepare a Preliminary Trip Generation Assessment for their proposed
projects. The need for a TIA shall be determined by the City’s Engineer based upon the information included
in the Preliminary Trip Generation Assessment and the criteria in Section 5.9.3 below.
A trip generation assessment shall be required for all proposed developments. Developers Applicants shall
submit the City-adopted Trip Generation Assessment Worksheet (“TGA Worksheet”) as part of Traffic
Scoping submittal process. Refer to City’s TIA Scoping Checklist. The TGA Worksheet must reflect
unadjusted trip generation projections for the proposed development, prepared in accordance with the
following resources and methodologies:
A. Trip forecasts shall be based on the most recent edition of the Institute of Transportation Engineers
(ITE) Trip Generation Manual. Applicants Developers shall utilize conservative trip estimates,
specifically values falling between the Average Rate and Fitted Curve Equation, where both are
provided.
B. If an appropriate ITE Land Use Code is not available, applicants may submit empirical trip generation
data from comparable facilities of similar size and function within the Dallas–Fort Worth
metropolitan area. Supporting documentation must include a detailed description of the data
collection methodology, a demonstration of land use comparability, a description of site conditions,
and verification of data reliability. If alternative data sources are used, applicants must provide
justification and supporting documentation. All alternative data sources are subject to review and
approval by the City’s Engineer.
The City’s Engineer shall evaluate the TGA Worksheet, in combination with the thresholds and criteria
specified in Section 5.9.3, to determine whether a Traffic Impact Analysis (TIA) is required for the proposed
development.
5.9.3 When is a TIA required?
Based on the preliminary trip generation assessment TGA Worksheet for the proposed project, unless
otherwise directed by the City ‘s Engineer, a TIA will be required for the following conditions:
A. Development will generate equal to or more than 50100 Peak-Hour Trips (PHT).
B. Development will generate equal to or more than 1,000 vehicle trips per day (VPD).
C. Project area to be developed is equal to or more than 100 acres.
D. Changes or alterations to the City Thoroughfare plan based on the Mobility Plan will be requested.
E. Access is taken from a TxDOT roadway, subject to both City and TxDOT TIA requirements.
F. Zoning changes that will negatively increase estimated traffic volumes above the current zoning
estimated traffic volumes.
G. Access is taken from an existing roadway with current traffic flow congestion based upon observed
conditions.
Section 5: Transportation Design Criteria
5.9 Traffic Impact Analysis Guidelines
5.9.4 TIA Category and Study Area ScopingRequirements
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H. Development plus recently approved or pending development projects which have not been
constructed located adjacent to the site and/or in proximity to the site, meet the above vehicular
trip criteria or acreage criteria as determined by the City’s Engineer.
I. If access is taken from a TxDOT roadway, check TxDOT TIA requirements.
5.9.4 TIA Category and Study Area ScopingRequirements
TIA Study Criteria
Table 5.9-A shows the number of analysis periods and study area limits for the TIA. Prior to developing the TIA, a
Preliminary Trip Generation Assessment shall be developed and reviewed with the City ’s Engineer, to verify the number
of analysis periods and the study area requirements.
If a TIA is warranted for a development under the conditions outlined in Section 5.9.3, the applicant shall
prepare and submit a TIA Scoping Memorandum in accordance with the City’s most recently adopted TIA
Scoping Checkl
st. The scoping process ensures consistency, transparency, and effective coordination between the applicant
and the City. A TIA will not be accepted for review without an approved TIA Scoping Memorandum.
The TIA Scoping Memorandum shall:
Establish the appropriate level of analysis for the proposed development (following Table 5.9 -A);
Define study area boundaries and identify required intersections and roadway segments (following
Table 5.9-A);
Identify traffic data collection requirements and study periods (following Table 5.9 -A); and
Confirm the methodologies, assumptions, and evaluation tools to be applied in the study.
Table 5.9-A shows the number of analysis periods and study area limits for the TIAs.
Table 5.9-A: Criteria for Study Requirements
Analysis
Category
Site Trips
Generated at
Full Build-Out
TIA Analysis Periods 1 Minimum Study Area 3
I >50-99 total
peak hour
driveway trips
1. Existing year
2. Opening year 2
1. All site access drives
II 100‐500 total
peak hour trips
1. Existing year
2. Opening year 2
3. Five years after opening
1. All site access drives
2. All signalized intersections and/or major
unsignalized intersections within ½-mile
to 1 mile of site boundary, depending on
total peak hour trips
Section 5: Transportation Design Criteria
5.9 Traffic Impact Analysis Guidelines
5.9.5 TIA Submittal RequirementsScoping and Report
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III >500 total
peak
hour trips
1. Existing year
2. Opening year of each
phase
3. Five years after initial
opening
4. Twenty years after final
opening with full build‐out
1. All site access drives
2. All signalized intersections and/or major
unsignalized intersections within 1-½
miles of site boundary and/or major
intersections along access routes to/from
regional corridors
Notes:
[1] Analysis periods shall include build and no‑build scenarios. Assume full occupancy when each phase opens.
[2] Assume full build‑out.
[3] For certain projects, the City may require an enlarged study area. Land uses within the study area should include recently
approved or pending development adjacent to the site and/or in proximity to the site.
Refer to the City of Denton TIA Scoping Checklist for further details.
5.9.5 TIA Submittal RequirementsScoping and Report
A. TIA Scoping
If a TIA is warranted for a development under the conditions outlined in Section 5.9.3, the
developers shall prepare and submit a TIA Scoping Memorandum in accordance with the City’s
most recently adopted TIA Scoping Checklist. The scoping process ensures consistency,
transparency, and effective coordination between the developers and the City. A TIA will not be
accepted for review without an approved TIA Scoping Memorandum.
The TIA Scoping Memorandum shall:
1. Establish the appropriate level of analysis for the proposed development (from Table 5.9-A);
2. Define study area boundaries and identify required intersections and roadway segments
(following Table 5.9-A);
3. Identify traffic data collection requirements and study periods (following Table 5.9 -A); and
4. Confirm the methodologies, assumptions, and evaluation tools to be applied in the study.
Refer to the City of Denton TIA Scoping Checklist for further details.
B. TIA Report
TIAs shall be prepared in accordance with the City of Denton TIA checklist, the approved TIA traffic
scoping, the Denton Development Code (DDC), and TxDOT standards, as applicable. At a minimum,
TIA reports shall address the following:
1. Project Description and Existing Conditions – Summarize the proposed development (land
use, size, location, phasing) and document existing roadway characteristics, intersection
control, traffic volumes, and any planned improvements within the defined study area.
2. Trip Generation, Distribution, and Future Conditions – Estimate trips per Section 5.9.2
methodology, assign them to the network, and evaluate traffic operations with and without
the project, considering background growth and approved developments.
3. Operational and Access Analysis – Assess performance of key intersections and roadway
segments (LOS, delay, v/c, queues), driveway spacing and sight distance, and internal
circulation. School developments shall include a Traffic Management Plan.
4. Multimodal and Safety Considerations – Identify pedestrian, bicycle, and transit impacts
along with any safety deficiencies.
Section 5: Transportation Design Criteria
5.9 Traffic Impact Analysis Guidelines
5.9.5 TIA Submittal RequirementsScoping and Report
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5. Mitigation Strategy and Commitments – Identify operational or safety issues resulting from
the proposed development and recommend appropriate mitigation, such as turn lanes,
signal adjustments, intersection or geometric modifications, access management strategies,
or multimodal enhancements. Proposed improvements should be clearly categorized by
timing and responsibility, distinguishing between those required at opening day and those
that may be phased or coordinated with other developments or agencies. Recommendations
must form a practical implementation plan demonstrating how anticipated impacts will be
effectively addressed.
The City’s Engineer reserves the right to request additional data, analyses, or scenarios based on
project scope or site-specific conditions. Refer to the City of Denton TIA Checklist for detailed
formatting and submittal requirements.Specific Requirements of the TIA Report
TIA Report must comply with this section, Denton Development Code (DDC), and TxDOT Standards
where applicable, and include but not limited to the following elements:
Cover page including the following: Name of the development; city- assigned project number;
contact information of the developer, owner, applicant, and engineer; and date of preparation
(updated with each review).
Traffic Scope – Approved TIA scoping# TSCXX-YYYY must be included in the Appendix of the report.
Any changes from approved scope must be discussed with the city and documented before TIA is
submitted.
Table of Contents – Include List of Figures, Tables and Appendices.
Executive Summary of the report, including project address, existing zoning and any proposed
changes, existing site conditions, proposed development including size & access, general
assumptions, traffic analysis summary and recommended mitigation measures
Introduction that describes the development project and its proposed phasing, description of the
surrounding land uses, and traffic generating modes.
Mobility Plan & City/TxDOT roadway construction projects.
List if roadways adjacent to the development are in city’s mobility plan, include classification, ROW,
pavement & sidewalk requirements (refer to 2024 Standard details)
Indicate if any roadways are in City’s Capital Improvement Program (CIP) or have a TxDOT
design/construction project.
Identify any improvements to the roadway sections per DDC 7.8.7.B
Traffic Exhibits - include the following exhibits in the TIA:
Site Location map showing all study intersections, site driveways, traffic control at study
intersections
Conceptual site plan – Include street names, all proposed driveway approaches
Existing lane usage and traffic control at all study intersections
Map showing location of all background projects assumed in the TIA (when applicable)
Traffic Volumes Exhibits (must show roadway link volumes)
Existing Traffic Volumes
No-Build/Background Traffic Volumes
Trip Distribution to include distribution from all external links and at site driveways
Site Generated Traffic Volumes – Include Site Trip Generation Table in the exhibit
Section 5: Transportation Design Criteria
5.9 Traffic Impact Analysis Guidelines
5.9.5 TIA Submittal RequirementsScoping and Report
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Build/Total Traffic Volumes
Proposed lane usage & Traffic Control at all study intersections (show mitigation in different
color/legend)
Trip Generation – Provide a trip generation table using the latest edition of Institute of
Transportation Engineers (ITE) Trip Generation Manual (use conservative trips between average rate
and fitted curve). See example below:
Include Daily Trip Generation for each use at full build-out. If development intends to include
phasing, Provide trip generation for each phase and overall development combined.
AM and PM (and Weekend if necessary) Peak Hour Trip Generation for each use at full build-out
Summary table and backup tables for calculation methods
Trip Distribution and Assignment
a. Include methodology
b. Show all external ink distribution
c. For Entrance/Exit from the development
d. For boundary streets within study area
Existing and Projected Traffic Volumes
a. Average Daily
b. Peak Hourly AM and PM
c. Weekend Peak Hours (specifically for Religious facilities, Major Shopping Centers and Special
Generators)
d. All traffic volume exhibits must include roadway link volumes
Traffic Study Elements
a. Intersection Capacity/Level of Service Evaluation for AM and PM Peak Hours
Identify all thoroughfares, driveways, intersections, and individual movements that do not meet
LOS D.
Identify mitigation for movements where site traffic is deteriorating beyond LOS D. For intersections
that are at LOS E/F in the background condition, mitigation must be identified to maintain or
improve Volume to Capacity ratio and delay to background condition.
Improvements to mitigate background condition’s LOS E/F cannot be assumed unless there are
committed projects by City or TxDOT.
b. Roadway Link Capacity Analysis
c. Parking Demand Analysis (if proposing alternative parking standards per DDC 7.9.5)
Section 5: Transportation Design Criteria
5.9 Traffic Impact Analysis Guidelines
5.9.5 TIA Submittal RequirementsScoping and Report
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Site Access Evaluation (Include applicable tables and exhibits)
Driveway approach standards & spacing per city or TxDOT standards when applicable,
Sight distance evaluation,
Median Access evaluation or TxDOT standards when applicable.
Turn Lane Warrants/Requirement
Turn Lane Geometry (storage and taper requirements), or TxDOT standards when applicable
Signal Warrant Analysis as needed for the study intersections or determined by the City of Denton
Engineer or designee.
Queue Analysis for all drive-through facilities and Gated Entries.
Bicycle and Pedestrian Infrastructure Evaluation
Per City Mobility Plan & Roadway classification – Include required width details.
Bicycle Paths/Routes and Trail Connection Assessment
Safety Assessment – Evaluation of Historic Crash Data.
Traffic Management Plan (TMP) for school development or expansion
Conclusions and Recommendations - The report shall include the findings from above sections and
include recommended mitigation measures that are the responsibility of the proposed
development.
Dependent upon the site characteristics, the City’s Engineer may require additional information to
be included in the TIA.
At a minimum the TIA report will include the following items:
Introduction that describes the project and traffic generating modes.
Traffic Analysis Map:
Existing and Proposed Land use within Study Area.
Study Area Boundary.
Existing and Proposed Roadways.
Designation of Traffic movement elements.
Thoroughfare Plan Elements within Study Area
Trip Generation Calculations as per the most recent ITE Trip Generation Manual:
Daily and Peak Hourly Trip Generation for fully developed project conditions. Include both AM and
PM Peak Hours. Provide Summary table and backup tables for calculation methods.
Discount assumptions based upon City’s Engineer’s approval.
Trip Distribution and Assignment Tables and Figures:
For Entrance/Exit from the development.
For boundary streets within study area.
Existing and Projected Traffic Volumes for Study based upon Table 5.9-A above:
Average Daily.
Peak Hourly AM and PM.
Additional Traffic Volume Data Provided by the City’s Engineer.
Traffic Volume Analysis:
Section 5: Transportation Design Criteria
5.9 Traffic Impact Analysis Guidelines
5.9.6 School Traffic Management Plan
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Level of Service Evaluation for AM and PM Peak Hours.
Turn Lane Evaluation for project site and study area. The extent of evaluation to be determined by
the City’s Engineer.
Signalization Evaluation for project site and study area. The extent of the evaluation to be
determined by the City’s Engineer.
Identification of all thoroughfares, driveways, intersections, and individual movements that do not
meet LOS-D.
Recommendations:
Proposed recommendations to mitigate impacts to transportation system within the study area.
Document Requirements: The following provides a general outline for the TIA report:
Executive Summary
Introduction
Purpose
Methodology
Existing and Proposed Land Use
Site Traffic Generation
Existing and Proposed Traffic Flow
Transportation System
Transportation Volumes
Traffic Analysis
Level of Service Evaluation
Turning Movement Evaluation
Signalization Evaluation
Active Transportation Impact Evaluation
Bicycle Paths/Routes and Trail Connection Assessment
Pedestrian Impact Analysis
Safety Assessment
Mitigation
Conclusions and Recommendations
Additional Requirements
Dependent upon the site characteristics, the City’s Engineer may require additional information to
be included in the TIA.
5.9.6 School Traffic Management Plan
A. Purpose
Schools generate atypical traffic conditions that require special consideration. They produce higher-
than-usual vehicular traffic, concentrated traffic loads at specific times, and a mix of different vehicle
types. Consequently, traffic management should be given the highest priority when evaluating new
school sites, upgrading existing sites, or reviewing ongoing school operations.
A School Traffic Management Plan (TMP) is a site-specific plan that addresses the school campus
Section 5: Transportation Design Criteria
5.9 Traffic Impact Analysis Guidelines
5.9.6 School Traffic Management Plan
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and adjacent street network. It
provides guidelines to coordinate traffic circulation during school peak hours, ensuring that all
road users are safely and efficiently guided through the site while maintaining the performance of
the roadway and minimizing impacts on surrounding properties.
D.B. Applicability
A TMP is required for:
1. Any new school development; or
2. Developments that are expected to significantly impact traffic operations at an existing
school.
The TMP must be prepared and submitted as part of the TIA to demonstrate that traffic conditions
at school access points have been adequately evaluated and mitigated.
E.C. TMP Preparation and Certification
1. The TMP shall be prepared by a licensed Professional Engineer (PE) in the State of Texas with
expertise in transportation and traffic engineering, preferably certified as a Professional
Traffic Operations Engineer (PTOE).
2. Field observations of both morning drop-off and afternoon pick-up periods shall form the
basis of the TMP.
3. The TMP must be signed, stamped, and dated by the licensed PE and include a statement
confirming that it was developed with input from individuals familiar with the site’s traffic
characteristics, including contact information for the approving school administration official.
4. The TMP should be prepared in a format suitable for distribution to parents, students, and
school staff.
F.D.TMP Content Requirements
The TMP shall include, at a minimum, the following elements:
1. Site and Roadway Description
a. Location of the school site and description of adjacent roadways.
b. All points of vehicular and pedestrian access (ingress and egress).
2. TMP Exhibit
a. Scaled site diagram showing building footprints, curbs, pavement markings, parking
areas, and designated student drop-off and pick-up locations.
b. Aerial images are not acceptable due to replication challenges.
3. Traffic Operations
a. Summary table indicating school schedule, student enrollment by grade, maximum
vehicular accumulation, on-site storage capacity, and surplus during dismissal periods
or at designated loading zones.
b. On-site traffic circulation plan, including any temporary traffic control devices.
c. Proposed coordination system for student drop-off and pick-up (e.g., passenger
identification, separation of transportation modes, and staggered arrival/dismissal
times).
Section 5: Transportation Design Criteria
5.9 Traffic Impact Analysis Guidelines
5.9.8 Safety Assessment
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4. Staffing and Supervision
a. Number and location of school staff assisting with loading/unloading students, with
roles and responsibilities clearly defined.
b. Number and location of adult crossing guards or off-duty law enforcement personnel.
5. Pedestrian and Bicycle Considerations
a. Identification of pedestrian routes up to 0.5 miles from all school access points.
b. Strategies to encourage walking and biking.
6. Parking and Parent Communication
a. Parking management strategies for on-site and nearby public areas.
b. Communication plan to inform and engage parents, students, staff, and neighbors
regarding the TMP.
7. Additional Considerations (if applicable)
a. School bus loading and unloading operations.
b. Methodology for projected maximum vehicular accumulation.
c. Traffic control plan showing signage on public rights-of-way.
8. High-Speed Roadway Considerations
8. : For schools adjacent to roadways with posted speed limits of 35 mph or greater, the TMP
shall include:
a. Turning movement counts at all major intersections adjacent to the school.
Stopping and intersection sight distances at all school driveway approaches.
d.b.
5.9.55.9.7 Safety Assessment
Consistent with the recently adopted Mobility Plan, safety is the number one priority for the City of Denton
and as such, all new developments will be required to conduct a safety assessment as part of their TIA. The
safety assessment will include a review of safety for all road users (vehicles, pedestrians and bicycles) within
the project site as well as along existing public ROWs in the vicinity of the project. The assessment will
include a review of the following:
A. Within the project site (Site Circulation).
B. All new intersections including project driveways.
C. Evaluation of Historic Crash Data at all existing intersections and roadways are included in the TIA.
5.9.8 Queue Analysis for Drive Through Facilities
A review of proposed drive through operations must be included in the TIA. The evaluation must include:
A. Illustration of proposed operations (i.e. access points and queue formation).
B. Anticipated maximum demand/queue (preferably based on observations of other existing sites with
similar characteristics or using service rate queue analysis).
C. Maximum queuing capacity on-site.
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5.9 Traffic Impact Analysis Guidelines
5.9.9 TIA Submission and Review Procedures
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D. Mitigation plan (Exhibit showing site plan) for if/when traffic ever exceeds design capacity to
prevent queues blocking sidewalks or travel lanes of adjacent roads. The plan needs to show how
the operator would have to manage longer queues without compromising safety (e.g. double
queue, cones, pavement markings, signs, etc.). The plan needs to be signed by the traffic engineer
whom the City would contact if/when needed to resolve back up problems once the tenant is in
operations - —same as the traffic study.
E. The following information must also be included:
1. Peak hour turning movements at intersections with driveway during AM & PM peak hours
of adjacent street.
2. Average Daily Traffic on abutting street.
3. Show adjacent street traffic lane configuration, dedicated turning lanes, traffic control.
9.4. Site plan showing all dimensions of all driveways, sidewalks, crosswalks.
5.9.6 TIA Submission and Review Procedures
5.9.7 A Preliminary Trip Generation Assessment of the proposed development shall
be conducted to determine the TIA requirements such as limits of study area, need
and type of turning movement evaluation, need for signalization evaluation,
discount assumptions that can apply, and criteria to be used. Sufficient base
information shall be submitted to the City’s Engineer in order to provide proper
guidance on TIA requirements for the report. Subsequent to the submittal of the
preliminary trip generation assessment, a meeting with the City’s Engineer should
be scheduled to discuss the specific requirements for the TIA.
5.9.8 Upon completion of the TIA report, two (2) copies of the report shall be
submitted to the City’s Engineer for review.
5.9.9 After a TIA is approved and if the development proposed land use and/ or
proposed traffic generation characteristics change, the TIA shall be updated and re-
submitted to the City for approval.
A. Trip Generation Assessment
The Trip Generation Assessment, as described in Section 5.9.2 of this Manual, must be completed
and submitted as Part A of Traffic Scoping submission to see if a TIA is required.
B. TIA Scoping (TSC) Memorandum
1. If a TIA is required (as determined in the Trip GenerationTGA worksheet), or clearly warranted
under conditions in Section 5.9.3, TIA Scoping must be submitted following the direction
provided in section 5.9.4, 5.9.5.A & the cCity’s TIA Scoping Checklist Past B section.
2. The TIA scope must be reviewed and approved by the City prior to TIA application submittal.
B.C. TIA Report Submission
TIA Report Submission must follow Section 5.9.5.B and the City’s TIA checklist.
Upon completion of the TIA, two (2) copies of the report shall be submitted to the City’s Engineer
Section 5: Transportation Design Criteria
5.9 Traffic Impact Analysis Guidelines
1.1.1 Bike/Ped TIA
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for review.
D. TIA Updates
If the development’s proposed land use or traffic generation characteristics change after TIA
approval, the TIA must be updated and resubmitted to the City for approval.
All existing intersections included in the TIA.
5.9.9 Bike/Ped TIA
All projects are expected to achieve the minimum acceptable LOS standard for onsite and off -site bicycle
and pedestrian facilities. Pedestrian and bike facility demand shall be identified and related items for
discussion should include:
A. School routing plans per the TMUTCD between the project and all schools within ½-mile of the
project boundary.
B. The demand for pedestrian and bike facilities to serve high pedestrian activity areas within the land
use.
C. The need for links of bicycle or pedestrian facilities to neighboring land uses or attractions (trails,
etc.) within ¼-mile (or greater if applicable to unique pedestrian-oriented destinations) of the
project site.
D. Existing and proposed sidewalk width, separation from traffic, and space available for trees, transit
stops (if any), or other related elements (if any).
E. Geometric improvements and recommended traffic control devices to accommodate pedestrians
and bicyclists.
F. Existing and proposed pedestrian and bike facilities shall be evaluated for compliance with the
following elements:
1. Directness. Walking distance to destinations like transit stops, schools, parks, and commercial
or activity areas should be direct. Measurement of directness is the ratio of the actual
distance to a destination via a sidewalk or pathway divided by the minimum distance
characterized by a grid street system.
2. Continuity. The sidewalk/ walkway system should be complete, without gaps. The pedestrian
corridor should be integrated with the activities along the corridor and should provide
continuous access to destinations.
3. Street Crossings. Safety and comfort is essential while crossing streets, intersections and mid-
block crossings. Factors that affect the LOS include: number of lanes to cross, crossing delay
for pedestrians, signal indication, cross-walks, lighting, raised medians, visibility, curb ramps,
pedestrian buttons, convenience, comfort, and security.
4. Visual Interest and Amenity. Pedestrians enjoy visually appealing environments that are
compatible with local architecture and include street lighting, fountains, and benches.
5. Security. Pedestrians should be visible to motorists, separated from motor vehicles and
bicycles, and under adequate street lighting.
6. Surface Condition. Pedestrian facilities should be free from obstructions, cracks, and
interruptions.
Section 5: Transportation Design Criteria
5.9 Traffic Impact Analysis Guidelines
1.1.1 Bike/Ped TIA
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The pedestrian Level of Service for the facility/corridor linking these destinations to the project site
will be based on the directness, continuity, types of street crossings, walkway surface condition,
visual interest/amenity, and security of the selected route(s), as shown in Table 5.9-B below.
Table 5.9-B: Bike/Ped TIA Criteria
Quality
Indicators A B C F
Security
Well used, good
lighting
levels and unobstructed
lines of sight
Unobstructed lines
of sight, good
lighting levels
Sidewalk configuration
and parked cars present
sight problems,
moderate lighting
Major pedestrian
visibility problems,
streetscape is
pedestrian intolerant
Directness
(Sidewalk Distance/
Minimum Distance)
< 1.4 1.4 - 1.8 1.8 - 2.2 > 2.2
Continuity
Quality, continuous
pedestrian networks
that are physically
separated from street
and built to current
standards
Continuous sidewalk
network on both sides
of the street. May not
be built to current
standards
Sidewalk network
where there may not be
sidewalks on both side
of the street or there
are minor interruptions
in connectivity
Breakdown in
pedestrian network to
where each pedestrian
chooses a different
route
Section 5: Transportation Design Criteria
5.9 Traffic Impact Analysis Guidelines
1.1.1 Bike/Ped TIA
Design Criteria Manuals 140
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Street Crossings
(Signalized
Intersections)
3 or fewer lanes to
cross, clear indications
(striping, etc.), well-
marked crosswalks,
good lighting, standard
curb ramps, automatic
pedestrian signal,
pedestrian amenities,
unobstructed views
4 or 5 lanes to cross,
clear indications, well-
marked crosswalks,
pedestrian refuge area,
standard curb ramps,
pedestrian amenities,
standard curb ramps,
unobstructed views
6 or more lanes to
cross, clear indications,
well-marked crosswalks,
pedestrian refuge area,
standard curb ramps,
pedestrian amenities,
unobstructed view
Missing 5 elements of
A, 4 elements of B, and
2 elements of C
Street Crossings
(Unsignalized
Intersections)
Well-marked cross
walks, good lighting
levels, standard curb
ramps, street character
suggests pedestrian
crossing, unobstructed
views
Missing 1 element of A Missing 2 elements of A Missing 3 or more
elements of A
Visual Appeal and
Pedestrian Amenities
Visually appealing and
compatible with local
architecture and artist
themes, wide sidewalks,
window shopping,
pedestrian lighting,
trees and street
furniture
Wide sidewalks, visual
clarity, some street
furniture and
landscaping
Functionally operational
with less importance
placed on visual appeal
Design ignores
pedestrian with
negative metal image,
intimidating
Surface Condition
Smooth asphalt or
concrete with few
breaks or cracks
Relatively smooth
asphalt or concrete with
frequent breaks or
cracks
Rougher, broken
surface such as older
concrete or
cobblestone
Difficult, unpaved
terrain such as hiking
trails
Table 5.9-C below can be used to identify the pedestrian destinations within ¼-mile (½ mile for schools) of
the project boundary.
Table 5.9-C: Bike/Ped Destination Identification
DESTINATION ORIGIN (project land use) RECREATION RESIDENTIAL INSTITUTION OFFICE/
BUSINESS COMMERCIAL INDUSTRIAL OTHER
(SPECIFY)
RECREATION
RESIDENTIAL
INSTITUTION (SCHOOL,
CHURCH, CIVIC)
OFFICE/BUSINESS
COMMERCIAL
INDUSTRIAL
OTHER
(SPECIFY)
Section 5: Transportation Design Criteria
5.10 Pavement Design Standard
5.10.2 Streets
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5.10 Pavement Design Standard
5.10.1 Streets
The minimum pavement section requirements for each classification of roadway are contained within the
City of Denton Standard Details for pavement cross-sections.
A. A geotechnical report shall be prepared that documents the existing soil characteristics of the
proposed roadway subgrade for any proposed street improvements. Soil testing shall be performed
whenever the soil characteristics change or every 500 feet, whichever is less. The report shall include
recommendations for the type and treatment level of subgrade stabilization based upon ultimate
traffic conditions.
B. Flex-base may be used as an option for subgrade treatment. Depth of flex-base required shall be
based upon the geotechnical report for the street improvements based upon ultimate traffic
conditions.
C. Alternative pavement sections may be proposed only if supported by a geotechnical report that
provides sufficient evidence to demonstrate that the alternate section shall meet the ultimate traffic
loading requirements.
5.10.2 Drive Approach
Refer to the City of Denton Standard Details for drive approach section requirements.
5.11 Complete and Context-Sensitive Streets
Complete streets are transportation facilities that are planned, designed, operated and maintained to
provide safe mobility for all users (including bicyclists, pedestrians, transit vehicles, truckers and motorists)
appropriate to the function and context of the facility. Context-sensitive solutions formulate a complete
street design considering contextual applications. Contextual applications can be of geographical nature
such as Urban Core, General Urban, Suburban, University Core and other typical service areas that require
unique components to address the overall transportation facilities.
Within the geometric standards are options that relate to developing a complete street that accounts for
all transportation facilities within the context of the associate area. Connectivity and context -sensitive
solutions are essential to meeting the goals of the standards. Refer to the City of Denton Standard Details
for cross-section details, and the pedestrian and bicycle components of the 2022 Mobility Plan for planned
facilities, or as required by the City of Denton during development review.
BIKE LANES – Bike lanes shall be six (6) feet wide unless otherwise approved by the City’s Engineer. Buffered
or separated bike lanes are generally preferred to increase level of comfort in the bicycle facility.
OFF-STREET MULTI-USE PATH – Some development areas will warrant the use of off-street multi-use
paths for pedestrian and bicycle traffic connectivity to other facilities as identified by the City of Denton.
Multi-use paths shall be 10 feet wide, unless otherwise approved by the City’s Engineer.
TRANSIT – Bus stop locations may be required by the City of Denton for connectivity of the transit system.
See Section 5.8 of this Manual for details.
Section 5: Transportation Design Criteria
5.11 Complete and Context-Sensitive Streets
5.10.2 Drive Approach
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MEDIAN VS. CONTINOUS LEFT TURN LANE – Selection of a median or continuous left turn lane shall be
based upon the TIA, connectivity, adjacent uses, and other factors required by the City’s Engineer. Medians
shall be 24 feet back of curb to back of curb, unless otherwise approved by the City’s Engineer. Continuous
left turn lanes shall be 11 feet wide.
MODIFICATIONS TO STANDARDS – Modifications to the standards may have to be considered in some
instances based upon context-sensitive use. An example of context-sensitive use which may require the
standards to be modified is a roadway corridor restriction that creates limitations that cannot be altered.
An example of a roadway corridor restrictions would be existing infrastructure and/or buildings that must
remain. Another example is infill development. Modifications to the standards based upon context-sensitive
use shall be at the sole discretion of the City’s Engineer.
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Section 6: Water and Wastewater Design
Criteria
6.1 Overview
The purpose of Section 6 - Water and Wastewater Design Criteria is to provide minimum, non-exhaustive
guidelines criteria for the design and construction of water distribution and wastewater collection systems
within the City of Denton, Texas and its extraterritorial jurisdictions.
Section 6: Water and Wastewater Design Criteria is organized as follows:
A. Overview
B. Water Distribution System Design Guidelines
C. Wastewater Design GuidelinesWastewater Collection System Design
D. Construction Plans
It is the responsibility of the design engineer to ensure the final design of water distribution and wastewater
collection systems are in conformance with the most recently adopted versions of the following documents:
A. Texas Administrative Code (TAC) Title 30, Part 1, TCEQ – Ch. 290;
B. Texas Administrative Code (TAC) Title 30, Part 1, TCEQ – Ch. 217;
C. Texas Administrative Code (TAC) Title 16, Part 2, PUCT – Ch. 24;
D. City of Denton Code of Ordinances and the DDC;
E. The City of Denton’s Standard Details and Standard Specifications for Construction;
F. City of Denton Water Distribution System Master Plan ;
G. City of Denton Wastewater Master Plan;
H. American Water Works Association (AWWA) Standards;
I. The International Building Code (IBC);
J. The International Plumbing Code (IPC);
K. The International Fire Code (IFC); and
L. This Manual.
The criteria established in Section 6 of this Manual provide basic guidance for the design of water and
wastewater systems. However, full responsibility and liability for proper design remains with the design
engineer. Users of this Manual should be knowledgeable and experienced in the theory and application of
water and wastewater engineering. If criteria established in Section 6 overlap with state statutes, rules, or
regulations, the more stringent requirement shall apply. The criteria established in this Section do not
supersede the criteria contained in the DDC. In the case of conflict between this Section, City of Denton
Standard Details, or other cited City regulations and standards, the more stringent requirement shall apply.
The Director General Manager of Water Utilities and Street Operations reserves the right to require
extended review, direct the design, location specifications and details of vertical water utility infrastructure,
and large horizontal infrastructure including, but not limited to, water treatment plants (WTPs), elevated
Section 6: Water and Wastewater Design Criteria
6.2 Water Design CriteriaGuidelines
6.2.1 Organization
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storage tanks (ESTs), booster pump stations, water transmission mains over 16 inches in diameter or greater,
wastewater reclamation plants, peak flow detention facilities, sewer lift stations and sewer interceptors over
12 inches in diameter. The Director General Manager of Water Utilities and Street Operations reserves the
right to deny proposals at his or hertheir discretion.
6.1.1 Organization
Section 6 - Water and Wastewater Design Criteria is organized as follows:
A. Overview
B. Water Design Criteria
C. Wastewater Design Criteria
D. Construction Plans
6.2 Water Design CriteriaGuidelines
6.2.1 Size of Water Distribution MainsDistribution System Extensions
A. General
Water mains shall be sized to meet the calculated water demand, fire flow protection requirements,
and to conform to the City of Denton’s Water Distribution System Master Plan (Water Master Plan
or WMP). All residential, commercial, industrial, and any other development connecting to the
City’s water distribution system shall use the following guidelines:
1. The design engineer shall obtain the record drawing water maps from the Capital
Improvement Projects & Engineering Division and use the following criteria, based on the
City’s WMP, for sizing the water lines.
a. Average daily demand in gallons per capita per day = 160 GPCD
b. Maximum daily demand / Average daily demand = 2.0
c. Peak hour demand / Maximum daily demand = 1.5
d. For Single-Family Residential – Use 3.2 people/unit
e. For Multifamily Residential – Use 2.5 people/unit
f. Refer to 30 TAC § 290.45 (d)(1) Table A - Non-community water systems
2. Water distribution systems extensions shall be provide d with sufficient number of
connections to the City’s existing water system, and integrating existing main extensions to
the development (including dead-end mains) from adjacent properties to the system
extension, for the demand of the proposed extension and shall be extended to neighboring
properties for subsequent system extensions. System extensions shall be of sufficient size to
furnish adequate domestic, irrigation, and fire protection water supply for fire protection to
all lots within the development and conform to the City WMP. Every new water system
extension shall include two (2) or more connections to the existing City water system when
feasible, to ensure an adequate and reliable water supply in the event of a water main break
or routine system maintenance. The City may require two (2) or more meter connections,
particularly for large and/or densely developed lotslarger developments. Good engineering
Section 6: Water and Wastewater Design Criteria
6.2 Water Design CriteriaGuidelines
6.2.1 Size of Water Distribution MainsDistribution System Extensions
Design Criteria Manuals 145
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judgement is required to ensure reliability is considered in the design of all proposed water
systems
3. Sites that require an irrigation meter shall have two separate service line connections onto
the main: one for the domestic meter, the other for the irrigation meter.
4. Water pipe shall be a minimum of eight (8) inches in diameter. The standard pipe sizes that
shall be used for water main lines are 8-in., 12-in., 16-in., 20-in., 24-in., 30-in., 36-in., and 42-
in. pipes. Pipe sizes of 6-in., 10-in., 14-in., 18-in., 21-in., and 33-in. are considered non-
standard by the City and shall not be used for water main lines. A 6-in. pipe may be used for
fire hydrant connections.
5.3. Every development shall provide adequate water capacity for fire protection purposes. Fire
flow capacity requirements are in addition to daily demand requirements. The procedure for
determining fire flow requirements for buildings or portions of buildings shall be in
accordance with the version of the IFC adopted by the City. For any platted lot where the
end use is not defined, the standards in Table 6.2-A shall apply
4. The cost for modeling a project’s impact with the City’s distribution system model will be the
responsibility of the developer and paid to the City.
B. Distribution System Operational Limits
The City observes the following operational limits for the distribution system under normal usage:
1. Maximum Vvelocity for proposed mains (greater than 16 inches): 3 fps, with up to 5 fps on
case-by-case basis
2. Maximum velocity for proposed mains (less than or equal to 16 inches or less) under non-
fire flow conditions: 5 fps
3. Maximum velocity for mains (12 inches or less) 12” and smaller under maximum day demand
+ fire flow scenario: 10 fps
2.4. Maximum head loss (less than or equal to 12 inches or less): 5 feet per 1,000 feet
3.5. Maximum head loss (greater than or equal to 16 inches or more): 3 feet per 1,000 feet
4.6. Hazen-Williams Roughness Coefficient (C): 130
Proposed impacts to the City’s system determined to, or likely to, cause (through hydraulic
modeling or other analysis) these limits to be exceeded, are prohibited without additional
improvements to the public system so the system can be operated within these parameters to allow
proper operation of the system.
Table 6.2-A: Water Capacity for Fire Flow
Area GPM
One (1) and two (2) family dwellings - less than 3,600 sq. ft. 1,000
Buildings other than one (1) and two (2) family dwellings - less than 3,600 sq. ft. 1,500
Medium-intensity commercial and light industrial 3,000
Section 6: Water and Wastewater Design Criteria
6.2 Water Design CriteriaGuidelines
6.2.1 Size of Water Distribution MainsDistribution System Extensions
Design Criteria Manuals 146
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High-intensity commercial and industrial 4,000
Notes:
[1] All fire flows to be calculated with 20 psi residual pressures.
[2] In addition to the fire flow requirements specified above, all developments shall provide adequate water capacity
to satisfy the greater of: (a) Peak Hour demand for the Peak Day, or (b) Average Hour demand plus fire flow for the
Peak Day.
[3] Special exceptions to the above standards may be made by the City’s Engineer for unique situations.
C. Public Fire Hydrants
Fire flow requirements shall be in accordance with the IFC as adopted by the City of Denton or
Denton County, as appropriate.
D. Private Fire Mains
In addition to the requirements of Section 6.2.12.B of this Manual above, private fire protection
water mains shall be installed in accordance with NFPA 24 and 2021 the adopted IFC requirements.
Private fire protection mains and associated hydrants shall be permitted by the Fire Marshal’s Office
with jurisdiction over the area.
E. Fire Flow Tests
Fire flow tests are normally requested by the design engineer, the Mechanical, Electrical and
Plumbing (MEP) engineer, and other engineers to determine available water system capacity at or
near the point of interest. If a fire flow test on the existing water system is necessary, contact the
Water Distribution Metering Department at FireFlowTesting@cityofdenton.com (940) 349-8456
directly.
F. Pressure Planes
The City of Denton’s Water Distribution System is divided into several water pressure planes to
ensure even water-pressure gradients. Prior to the design of connection points between a
proposed main and any existing main, the design engineer shall investigate and determine if the
proposed water main crosses the boundary between different pressure planes.
Even though physical connections of water pipes exist between pressure planes, they are designed
with valves which are closed at the boundary points so that each pressure planes is isolated.
Proposed mains that approach pressure planes boundaries shall be designed to loop within their
designated pressure planes and with no or minimum lengths of dead-end mains.
Connections between pressure planes must be approved by the General Manager of Water Utilities
and Street Operations City’s Engineer and may require pressure-reducing valve stations. The design
engineer can determine the pressure planes boundaries by consulting the record drawings which
show the designated closed valves between pressure planes and by contacting Water Utilities. See
Figure 6.1 below for the 2025 Water System Pressure Plane Map.
The Central pressure plane operates at a Hydraulic Grade Line (HGL) of 826 feet and includes service
elevations between 540 feet and 700 feet. It is recommended that any areas above 700 feet be
served from the West pressure plane, if possible. An alternative to connecting new development to
the higher-pressure plane includes grading sites to be below 700 feet. Areas at elevations below
600 feet may experience high pressure. Individual Pressure Reduction Valves (PRVs) may be needed
to maintain an acceptable pressure range.
Eastern pressure planes (i.e. East and Southeast) have a HGL of 745 feet are supplied from the
Central pressure plan by reducing pressure via system pressure-reduction valves. Service elevations
for the eastern pressure planes range from 515 feet and 615 feet.
The West pressure plane operates at an HGL of 900 feet at the Northwest EST, 905 feet at the
Section 6: Water and Wastewater Design Criteria
6.2 Water Design CriteriaGuidelines
6.2.1 Size of Water Distribution MainsDistribution System Extensions
Design Criteria Manuals 147
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Southwest EST and includes service elevations between 670 feet and 770 feet. The boundary
between the West and Central pressure plane generally follows the 670-foot contour. Any areas at
elevations greater than 770 feet will not be able to be served by the existing distribution system
due to low static pressures. Areas near the suction side of the Southwest Boost Pump Station should
be served from the West pressure plane due to the decreased residual pressure in the Central
pressure plane in this area.
Section 6: Water and Wastewater Design Criteria
6.2 Water Design CriteriaGuidelines
6.2.1 Size of Water Distribution MainsDistribution System Extensions
Design Criteria Manuals 148
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Figure 6.1 2025 Water Master Plan Pressure Plane Map
Section 6: Water and Wastewater Design Criteria
6.2 Water Design CriteriaGuidelines
6.2.4 Water Main Horizontal and Vertical Alignment
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6.2.2 Water Main Horizontal and Vertical Alignment
The following guidelines should be followed by the design engineer in placement of water lines:
A. In existing streets, water lines shall be placed in the pavement four (4) feet from back of curb. For
new residential development, water lines shall be placed on the north and east sides of the streets,
where possible, four (4) feet from back of curb. See the City of Denton Standard Details.
B. All water lines shall be laid as straight as possible. Avoid excessive number of high points and low
points between cross street connections, as they trap air pockets. See Section 6.2.6.B of this Manual
for placement of air release valves.
C. Minimum radius of curvature and maximum deflection angle of pipe joints are restricted to the
manufacturer’s recommendation, after which, horizontal or vertical bends are required. Deflection
of pipe shall only be permitted through joint deflection; no bending of pipe is allowed.
D. Vertical bends shall be no greater than 45 degrees.
E. Except for transverse pipe crossings, no other utility shall be installed over, under or within five (5)
feet horizontally of a water line.
F. There shall be at least two (2) feet of vertical separation between a water line and any utility or
storm drain crossing it.
G. Water lines shall not be located closer than 10 feet to any building or structure, or located where
the excavation of which could place the stability of another structure in jeopardy.
H. Where distribution mains run parallel to transmission mains 16 inches or larger, a non-standard
cross-section detail will need to be coordinated with the Water Utility and accommodate the ROW
width, gravity and pressurized wastewater mains, reuse water mains and storm drainage mains.
E.I. The WMP is a guide for transmission main alignment and subject to formal and informal updates.
6.2.26.2.3 Depth of Cover for Water Mains
The following table shall govern depth of cover for water main installations:
Table 6.2-B: Minimum Depth of Cover for Water Mains
Pipe Size From Surface to Top of Pipe
UNDER UNPAVED AREAS UNDER PROPOSED OR EXISTING PAVEMENT
12-in. and smaller 5 feet 42 inches
16-in. - 5 feet
16-in. and larger 6 feet -
20-in. and larger - 6 feet
Notes:
[1] Additional depth of cover shall be required for low-lying areas where future drainage improvements are anticipated.
6.2.36.2.4 Pipe and Fittings
A. Specifying the appropriate pipe material is the responsibility of the design engineer, based on the
analysis of specific site and loading conditions, and pressure requirements. The minimum
requirements in this Section are based on pipe size only, and in no way relieve the design engineer
Section 6: Water and Wastewater Design Criteria
6.2 Water Design CriteriaGuidelines
6.2.4 Pipe and Fittings
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of the responsibility of specifying the pipe material applicable to the specific project. Pipe gasket
material shall be that recommended by the manufacturer for the specified pipe. Special attention
shall be given by the design engineer for unique pipe fitting and pipe assembly situations.
B. Water pipe shall be a minimum of eight (8) inches in diameter. The standard pipe sizes that shall
be used for water main lines are 8-in., 12-in., 16-in., 20-in., 24-in., 30-in., 36-in., and 42-in. pipes.
Pipe sizes of 6-in., 10-in., 14-in., 18-in., 21-in., and 33-in. are considered non-standard by the City
and may not be used for water main lines. A 6-in. pipe may be used for fire hydrant connections.
A.C. Water mains 16 inches” and greater in diameter shall have preplanned points of connection of no
less than 12 inches in” diameter for distribution extensions. Tees with branch valves shall be used
for preplanned connections.
B.D. See Table 6.2-C below for the City’s minimum pipe materials, fittings, polywrap, thrust restraint, and
embedment requirements, as a function of pipe size.
C.E. All fittings for pipe sizes less than 30 inches in diameter, including vertical and horizontal bends,
shall have concrete thrust blocking. See City of Denton Standard Details.
F. All vertical and horizontal fittings and valves shall require restrained joints in addition to concrete
thrust blocking. The joint restraints shall be designed as though there is no concrete thrust blocking,
and the concrete thrust blocking shall be designed as though there are no joint restraints. Flanged
tees should be used to secure all branch valves to fittings. Table 6.2-C below includes the minimum
lengths of pipe to be restrained for 8 -inch and 12-inch PVC water mains. For water lines greater
than 12 inches in diameter, additional restrained joints may need to be installed beyond the fitting
(i.e., may need to be installed on several pipe joints on each side of the fitting), depending on the
required restrained length calculated. Restrained length calculations shall be i ncluded in the lay
schedule in the material submittal package and shall use approved methods of joint restraint. See
City of Denton Standard Details, specific product listings and Table 6.2-C below.
G. Geot Technical reports detailing soil conditions, that may affect the design, operation , or
maintenance of water infrastructure are required. Corresponding corrosion protection systems are
to be provided for Ductile Iron and Concrete Steel Cylindermetallic pipe materials including reports
detailing the operation and maintenance of the corrosion protection systems. Corrosion system
design reports must be included with record drawings.
Table 6.2-C: Restraint Lengths for Fittings and Bends
Pipe Size
(inches)
Plugs, Tees, and
Valves 1 Bends 1
90° 45° 22.5° 11.25°
8 88 ft 33 ft 14 ft 7 ft 4 ft
12 126 ft 45 ft 19 ft 9 ft 5 ft
Notes:
[1] Length to be restrained on each side of the bend or fitting. Assumptions: 1.5 safety factor, SP soil type, Type 4 trench.
Section 6: Water and Wastewater Design Criteria
6.2 Water Design CriteriaGuidelines
6.2.4 Pipe and Fittings
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Table 6.2-D: Minimum Requirements for Pipe and Fittings
Pipe Size and Material Ductile Iron
Fittings
Polywrap
(Pipe &
Fittings)Corrosio
n Protection
Thrust Restraint Embedment
8-IN. TO 12-IN.
PVC
(AWWA C900, DR – 14)
Mechanical
joint;
Compact or
Full-Body
8-mil V-Bio
Enhanced Polywrap
(fitting only)
Wedge-action mechanical joint
restraint glands, at fittings.
See drawings U201,
U202, U203A,
U203C in
City of Denton
Standard Details
16-IN. TO 20-IN.
Ductile Iron,
AWWA C151,
Special Thickness Class 52,
push-on-joints
(where unrestrained;
e.g.: American Flex-Ring
joint)
Mechanical
joint;
Full-Body
8-mil V-Bio
Enhanced Polywrap
(inner layer), plus 4-
mil cross-linked
(outer layer) Bonded
joint and Cathodic
Protection (CP)
System required
Wedge-action mechanical joint
restraint glands, at fittings.
Boltless Restrained connections
(Example: American Flex-Ring
joint), at several pipe joints
either side of each fitting,
depending on the required
restrained length calculated.
See drawings U201,
U202, U203A,
U203C in
City of Denton
Standard Details
Reinforced Concrete Steel
Cylinder,
AWWA C303 Bar Wrapped
N/A Bonded joint and
Cathodic Protection
(CP) System required
Full Circle Welded Joints
required for thrust restraint
Contact Water
Utilities Dept.
24-IN.
Ductile Iron,
AWWA C151, Special
Thickness Class 52,
push-on joints
(where unrestrained;
e.g.: American Flex-Ring
joint)
Mechanical
joint;
Full-Body
8-mil V-Bio
Enhanced Polywrap
(inner layer), plus 4-
mil cross-linked
(outer layer) Bonded
joint and Cathodic
Protection (CP)
System required
Wedge-action mechanical joint
restraint glands, at fittings.
Boltless Restrained connections
(Example: American Flex-Ring
joint), at several pipe joints
either side of each fitting,
depending on the required
restrained length calculated.
Crushed Stone
Reinforced Concrete Steel
Cylinder,
AWWA C303 Bar Wrapped
N/A Bonded joint and
Cathodic Protection
(CP) System required
Full Circle Welded Joints
required for thrust restraint.
Contact Water
Utilities Dept.
30-IN. AND LARGER
Ductile Iron,
Pressure Class 350;
push-on joints
(where unrestrained; e.g.:
American Flex-Ring joint)
Mechanical
joint;
Full-Body
8-mil V-Bio
Enhanced Polywrap
(inner layer), plus 4-
mil cross-linked
(outer layer) Bonded
joint and Cathodic
Protection (CP)
System required
Wedge-action mechanical joint
restraint glands, at fittings.
Boltless Restrained connections
(Example: American Flex-Ring
joint), at several pipe joints
either side of each fitting,
depending on the required
restrained length calculated.
Crushed Stone
Reinforced Concrete Steel
Cylinder,
AWWA C303 Bar Wrapped
N/A Bonded joint and
Cathodic Protection
(CP) System required
Full Circle Welded Joints
required for thrust restraint.
Contact Water
Utilities Dept.
Section 6: Water and Wastewater Design Criteria
6.2 Water Design CriteriaGuidelines
6.2.5 Connections
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6.2.46.2.5 Connections
A. Methods of Connection
1. Tapping Sleeve and Valve
Tapping sleeves with tapping valves shall be used whenever possible for connections to
existing mains to avoid interruption of water services. See Figure 3.1 in Drawing PIAZ13 of
the City of Denton Standard Details.
a. As per AWWA C223, size-on-size taps are allowed up to 12 inches (e.g.: 12-in. x 12-in.)
b. Taps on pipes 16 inches and larger must be approved in writing in advance by the City’s
Engineer after demonstrating the demand is greater than the availability from the
distribution existing system. Taps to mains 16 inches and greater must be a minimum
of 12 inches and utilize an isolation valve of the same size as the tap. Extensions may be
reduced by fittings after the tapping valve. See Figure 3.2 in Drawing PIAZ13 of the City
of Denton Standard Details.
c. Connections to fire hydrant leads on existing mains 16 inches and larger may be allowed
on a case-by-case basis after consultation and written approval by the City’s Engineer.
d. All water service lines, two (2) inches and smaller, require taps as per City of Denton
Standard Details.
2. Cut-in Connection
Cut-in connections are only allowed to existing mains larger than 12 inches, where a size -
on-size connection is needed. See Figure 3.4 in Drawing PIAZ14 of the City of Denton
Standard Details.
3. Main Extensions
A new valve shall be installed at the point of connection for water main extensions. This will
facilitate the testing and chlorination of the new main prior to its placement into service. See
Figure 3.5 in Drawing PIAZ14 the City of Denton Standard Details.
Note that the developer is responsible for all surface rehabilitation associated with
connecting to the City’s Water Utilities. Surface rehabilitation must match existing site
conditions or better.
B. Flushing and Disinfection
Refer to all current City specifications and TCEQ requirements for Flushing and Disinfection.
Prior to making permanent connections to the distribution system, water distribution mains, valves, and
appurtenances shall be adequately flushed and disinfected in accordance with the most current revision to
AWWA C651, and bacteriological testing shall be completed to meet the standards established by the Water
Utilities Department and 30 TAC Chapter 290. Additionally, heavily chlorinated water shall be flushed from
all segments of the newly constructed mains before final connections are made.
Before commencement of construction of water distribution infrastructure, the contractor or engineer shall
submit a flushing and disinfection plan for review by the Department of Water Utilities. At a minimum the
plan shall describe:
A. Flushing procedures;
Section 6: Water and Wastewater Design Criteria
6.2 Water Design CriteriaGuidelines
6.2.6 Valves
Design Criteria Manuals 153
Published: July January 20264 Go to Table of Contents
B. Hydraulic calculations to demonstrate adequate flushing velocities, or demonstrate conformance
with the conditions outlined in AWWA C651 Table 3;
C. The method of chlorination;
D. Bacteriological sampling plan;
E. Dechlorinating procedures (Refer to AWWA C655); and
F. Disposal of chlorinated water and methods used to ensure discharges to surface waters or storm
sewer systems do not exceed 0.1 mg/L total chlorine.
6.2.56.2.6 Valves
A. Isolation Valves
1. Location
Isolation valves shall be provided to allow for the proper operation and maintenance of the
water distribution system, and to ensure water quality can be maintained for each individual
water customer connected to the system.
The location of valves needs to properly address the ability of the Department of Water
Utilities to remove a water line from service to perform necessary repairs, while critically
minimizing the interruption of service for fire protection and to customers. Isolation of any
given section of water line should generally be able to be accomplished by closure of the
least number of valves, as would generally be expected under good engineering design
practices and utility engineering standards. The Department of Water Utilities reserves the
right to require changes to proposed designs to satisfy these objectives.
The design engineer shall place valves on proposed water mains so they may be easily
located in the future by operations and maintenance crews.
The following guidelines should be used by the design engineer in placement of isolation
valves on proposed water mains:
a. Two (2) valves are to be installed at every main branch tee location, one (1) flanged to
the branch of the tee and the other a mechanical joint connection on one (1) of the two
(2) runs of the tee. See Figure 3.6 in Drawing PIAZ15 of the City of Denton Standard
Details. Three (3) valves are to be installed at every cross location, each a mechanical
joint connection.
b. Valves for line sizes 12 inches in diameter or less should not be spaced any farther apart
than 1,000 feet. For city blocks that are longer than 1,000 feet between street
intersections, placement of a valve will be required between street intersections.
c. Valves should be generally located so that no more than four (4) valves are required to
isolate a section of main. See Figure 3.7 in Drawing PIAZ15 of the City of Denton
Standard Details. For mains larger than 12 inches in diameter, valve spacing and
placement shall be subject to alternate criteria approved by the City’s Engineer.
d. All fire hydrant leads must be designed with a valve that is flanged to the main line. See
Drawings W401A and W401B of the City of Denton Standard Details.
2. Specifications
Section 6: Water and Wastewater Design Criteria
6.2 Water Design CriteriaGuidelines
6.2.6 Valves
Design Criteria Manuals 154
Published: July January 20264 Go to Table of Contents
Refer to Table 6.2-L and Standard Specifications 33 14 20 Resilient Seated (Wedge) Gate
Valves and 33 14 21 AWWA Rubber-Seated Butterfly Valves.
Table 6.2-E: Isolation Valve Requirements
Size 4-in. to 12-in. 16-in. to 20-in. 24-in. 30-in. 36-in. or larger
Type Gate Valve
(AWWA C509
resilient-seat)
Gate Valve
(AWWA C515
resilient-seat)
Gate Valve
(AWWA C515
resilient-seat)
Gate Valve
(AWWA C515
resilient-seat)
Gate Valve
(AWWA C515 resilient-
seat) or butterfly, to be
determined by City on a
case-by-case basis
Orientation Vertical Vertical Vertical Vertical or horizontal;
to be determined
by City on a
case-by-case basis
Vertical or horizontal; to
be determined by City
on a
case-by-case basis
Gear
Operator
Required
No No Yes Yes Yes
Vault
Required
No No Yes Yes Yes
Bypass
Required
No No No Yes Yes
3. Details
Refer to Drawings W104, W105, W106A, W106B, and W601 of the City of Denton Standard
Details.
B. Air Release Valves and Air/Vacuum-Air Release Valves
For water mains less than 16 inches in diameter in certain situations where the topography,
remoteness, or some other hydraulic factor necessitates it, air release valves are required at local
high points to facilitate automatic release of accumulated air.
For water mains 16 inches and larger, the City requires air/vacuum-air release valves at local high
points to facilitate automatic release of accumulated air and to facilitate automatic prevention of
vacuum conditions within the line. See Drawings W801 and W802 of the City Standard Details.
Manholes shall not be placed in sidewalks, pedestrian ramps, driveway approaches, or in the bottom
or on the slopes of a drainage channel or drainage structure. Manholes shall be kept a minimum of
40 feet from any railroad track.
C. Pressure Reduction Valves and Pressure Sustaining Valves
Public pressure reduction valves and pressure sustaining valves are to be coordinated with and
written approval obtained from the City’s Engineer in consultation with the Field Operations
division. Valves shall be located where they are accessible to City staff and located in a vault sized
for the valve assemblies and staff access in unpaved areas of ROW and/or PUE. PUEs shall be sized
considering the size of the vaults, depth of the water main, and site constraints, including, but not
limited to, highways, creeks, railroads, existing and proposed structures, ingress and egress
availability, topography, and ESAs.
D. Blowoff Valve Assemblies
Section 6: Water and Wastewater Design Criteria
6.2 Water Design CriteriaGuidelines
6.2.9 Dead-End Mains
Design Criteria Manuals 155
Published: July January 20264 Go to Table of Contents
Water mains 16 inches and larger shall be equipped with blowoff valve assemblies sized to facilitate
three (3) fps scouring velocities within the main, flushing and draining of the water main for
maintenance. Assemblies are to be located at low points where sediment can accumulate and to
ensure complete drainage of the main to allow for repairs to be completed on empty mains.
The discharge piping of the blowoff assembly must direct flushed water towards drainage
infrastructure without causing flooding. Erosion prevention must be included in the design of the
assembly and direction of discharged water. The location of the assemblies must be in a public
ROW or utility easement in an unpaved area large enough for operation of the assembly.
6.2.66.2.7 Dead-End Mains
A. Dead-end main situations should be avoided whenever possible, except for main extensions to
neighboring property for future extension.
G.B. In lieu of dead-end mains, the design should loop through public ROW or a dedicated public utility
easement (with adequate assurance of access and fencing prohibited) to another nearby water main
using the same size pipe.
H.C. If a dead-end main situation is unavoidable, it shall be designed so that it may be periodically
flushed of stagnant water by locating a fire hydrant or other flushing device near the main’s end
and past the last service connection. See City of Denton Standard Detail W603.
6.2.76.2.8 Fire Hydrant Locations and Coverage
A. The design engineer should locate fire hydrants as close as possible to street intersections, but
outside of the curb radius. This positioning of fire hydrants provides coverage along several streets.
When spacing requirements necessitate the installation of fire hydrants between street
intersections, they should be placed at the projection of lot lines between property owners. For
main replacement projects in established neighborhoods, fire hydrants should be designed as close
as possible to the old fire hydrant location, provided coverage is adequate. Neighborhood
residents are familiar with the fire hydrant being at that location and normally expect a replacement
fire hydrant to be placed at the same location. Fire hydrants are not to be installed closer than nine
(9) feet to any wastewater main, manhole, or appurtenance.
B. Fire hydrant spacing shall comply with the 2021 IFC Appendix C Fire Hydrant Locations and
Distribution, and be easily accessible by City staff and First Responders. See City of Denton Standard
Details W401A and 401B, and Standard Specifications 33 14 40 Fire Hydrants. Fire hydrants shall be
placed at a maximum of 500 feet apart in single-family residential areas and a maximum of 300 feet
apart in all other areas, unless a closer spacing is required by the IFC.
6.2.86.2.9 Meters and Meters Cans/Vaults
The City allows the following water meters, depending on the volume and nature of the customer flow
demands:
Table 6.2-F: Allowable Water Meters
Service
Size Meter Size Type AWWA Standard
1-in. ⅝-in. x ¾-in. Positive Displacement AWWA C700
Section 6: Water and Wastewater Design Criteria
6.2 Water Design CriteriaGuidelines
6.2.9 Meters and Meters Cans/Vaults
Design Criteria Manuals 156
Published: July January 20264 Go to Table of Contents
1-in. ¾-in. x ¾-in. Positive Displacement AWWA C700
1-in. 1-in. Positive Displacement AWWA C700
2-in. 1½-in. Positive Displacement AWWA C700
2-in. 2-in. Positive Displacement AWWA C700
4-in. 3-in. Tru/Flo Compound See City Standard
Specification 33 14 18
4-in. 4-in. Tru/Flo Compound See City Standard
Specification 33 14 18
6-in. 6-in. Tru/Flo Compound See City Standard
Specification 33 14 18
6-in. 6-in. Protectus III Fire Service
(Shall be used for combination of domestic and fire service) Compound See City Standard
Specification 33 14 18
8-in. 8-in. Protectus III Fire Service
(Shall be used for combination of domestic and fire service) Compound See City Standard
Specification 33 14 18
Notes:
[1] Turbine meters shall be allowed for irrigation meters; not for domestic meters.
[2] Venturi meters shall be allowed when recommended by City Water Utilities based on Single-Family Equivalent calculations.
[3] Fire hydrant meters shall only be used for non-potable purposes.
[4] Vaults are required for all meters greater than two (2) inches.
[5] See Section 6.2.9.D for Furnishing and Installing meters.
[6] Non-standard sized water services are not allowed. Refer to the water service connection drawings on the City of Denton Standard
Details.
[7] Sites that require an irrigation meter shall have two (2) separate service line connections onto the main; one (1) for the domestic
meter, and the other for the irrigation meter.
A. Number of Meters
One (1) meter is required for each residential, commercial, or industrial service connection, in
accordance with the Code of the City of Denton, Texas, Chapter 26, Article I, Sec. 26-9. An apartment
building, condominium, manufactured housing community, or mobile home park may be
considered a single commercial facility for the purpose of this section. The City’s standard policy is
that only one (1) meter for domestic use will be furnished to each lot. Exceptions to that policy are:
1. Multifamily, Ccommercial, industrial, or institutional sites shall have a separate irrigation
meter from the domestic meter with a separate service line to the distribution main;
2. Multifamily developments with greater than 200 units shall be required to have two (2)
domestic meters for redundancy and reliability of water service, where each meter is located
on a different water main or separated by an inline valve. Note that Fire Code may require
redundant (secondary) fire suppression connections;
3. Multi-building sites where the configuration or size of the site makes a single meter location
impractical or infeasible;
4. Institutional Group I-2 Facilities as per IBC Sec. 308.3 and IPC Sec. 609; and
5. Submetering by the property owner to tenants of multifamily developments with a minimum
of five (5) units per building (or by condominium associations to member) shall be done at
the owner’s expense, with privately purchased and maintained meters, and in accordance
with the Public Utilities Commission 16 TAC Chapter 24 Subchapter I, as amended.
B. Sizing
In commercial and industrial projects, the design engineer shall consult with the owner or the MEP
engineer to identify proposed sizes and locations for domestic water meters, fire sprinkler
connections, and irrigation meters.
Section 6: Water and Wastewater Design Criteria
6.2 Water Design CriteriaGuidelines
6.2.9 Meters and Meters Cans/Vaults
Design Criteria Manuals 157
Published: July January 20264 Go to Table of Contents
During Building Permit review, the City evaluates adequacy of meter size using Table E201.1,
“Minimum Size of Water Meters, Mains and Distribution Piping Based on Water Supply Fixture Unit
Values (w.s.f.u.)” of the version of the International Plumbing Code (IPC) as adopted by the City
(copy included herein as Table 6.2-G). The City’s Building Permit Plans Review uses the version of
the International Residential Code as adopted by the City, Table P2903.6, “Water-Supply Fixture-
Unit Values for Various Plumbing Fixture and Fixture Groups” (See Table 6.2-H) to estimate w.s.f.u.
To facilitate review of the proposed meter size, the design engineer shall submit a tabulation of
w.s.f.u.; a sample tabulation is provided herein in Table 6.2-J.
Contact the Water Utilities Department regarding criteria for sizing fire-rated master meters.
For commercial or industrial sites that utilize large amounts of water in their production process,
the developer shall provide estimated peak daily demand. Meter to be sized to 1.25 times (1.25x)
the peak daily demand.
The total service units for multifamily apartment projects with eight (8) or more units shall be
determined by multiplying the total number of bedrooms in the multifamily apartment project by
0.26 Single-Family Equivalents (SFEs).
Table 6.2-G: Minimum Size of Water Meters, Mains, and Distribution Piping
based on water-supply fixture-unit (w.s.f.u) values
Meter and
Service Pipe
(inches)
Distribution
Pipe
(inches)
Maximum Development Length (feet)
PRESSURE RANGE 30 TO 39 PSI 250 300 400 500
3/4 1/21 2.5 2 1.5 1.5 1 1 0.5 0.5 0 0
3/4 3/4 9.5 7.5 6 5.5 4 3.5 3 2.5 2 1.5
3/4 1 32 25 20 16.5 11 9 7.8 6.5 5.5 4.5
1 1 32 32 27 21 13.5 10 8 7 5.5 5
Section 6: Water and Wastewater Design Criteria
6.2 Water Design CriteriaGuidelines
6.2.9 Meters and Meters Cans/Vaults
Design Criteria Manuals 158
Published: July January 20264 Go to Table of Contents
Table 6.2-G: Minimum Size of Water Meters, Mains, and Distribution Piping
based on water-supply fixture-unit (w.s.f.u) values
3/4 1-1/4 17 13 10.5
1 1-1/4 80 80 70 61 45 34 27 22 16 12
1-1/2 1-1/4 80 80 80 75 54 40 31 25 17.5 13
1 1-1/2 87 87 87 87 84 73 64 56 45 36
1-1/2 1-1/2 151 151 151 151 117 92 79 69 54 43
2 1-1/2 151 151 151 151 128 99 83 72 56 45
1 2 87 87 87 87 87 87 87 87 87 86
1-1/2 2 275 275 275 275 258 223 196 174 144 122
2 2 365 365 365 365 318 266 229 201 160 134
2 2-1/2 533 533 533 533 533 495 448 409 353 311
PRESSURE RANGE 40 TO 49 PSI 40 60 80 100 150 200 250 300 400 500
3/4 1/21 3 2.5 2 1.5 1.5 1 1 0.5 0.5 0.5
3/4 3/4 9.5 9.5 8.5 7 5.5 4.5 3.5 3 2.5 2
3/4 1 32 32 32 26 18 13.5 10.5 9 7.5 6
1 1 32 32 32 32 21 15 11.5 9.5 7.5 6.5
3/4 1-1/4 32 32 32 32 32 32 32 27 21 16.5
1 1-1/4 80 80 80 80 65 52 42 35 26 20
1-1/2 1-1/4 80 80 80 80 75 59 48 39 28 21
1 1-1/2 87 87 87 87 87 87 87 78 65 55
1-1/2 1-1/2 151 151 151 151 151 130 109 93 75 63
2 1-1/2 151 151 151 151 151 139 115 98 77 64
1 2 87 87 87 87 87 87 87 87 87 87
1-1/2 2 275 275 275 275 275 275 264 238 198 169
2 2 365 365 365 365 365 349 304 270 220 185
2 2-1/2 533 533 533 533 533 533 533 528 456 403
PRESSURE RANGE 50 TO 60 PSI 40 60 80 100 150 200 250 300 400 500
3/4 1/21 3 3 2.5 2 1.5 1 1 1 0.5 0.5
3/4 3/4 9.5 9.5 9.5 8.5 6.5 5 4.5 4 3 2.5
3/4 1 32 32 32 32 25 18.5 14.5 12 9.5 8
1 1 32 32 32 32 30 22 16.5 13 10 8
3/4 1-1/4 32 32 32 32 32 32 32 32 29 24
1 1-1/4 80 80 80 80 80 68 57 48 35 28
1-1/2 1-1/4 80 80 80 80 80 75 63 53 39 29
1 1-1/2 87 87 87 87 87 87 87 87 82 70
1-1/2 1-1/2 151 151 151 151 151 151 139 120 94 79
2 1-1/2 151 151 151 151 151 151 146 126 97 81
1 2 87 87 87 87 87 87 87 87 87 87
Meter and
Service Pipe
(inches)
Distribution
Pipe
(inches)
Maximum Development Length (feet)
1-1/2 2 275 275 275 275 275 275 275 275 247 213
2 2 365 365 365 365 365 365 365 329 272 232
2 2-1/2 533 533 533 533 533 533 533 533 533 486
PRESSURE RANGE OVER 60 PSI 40 60 80 100 150 200 250 300 400 500
3/4 1/21 3 3 3 2.5 2 1.5 1.5 1 1 0.5
Section 6: Water and Wastewater Design Criteria
6.2 Water Design CriteriaGuidelines
6.2.9 Meters and Meters Cans/Vaults
Design Criteria Manuals 159
Published: July January 20264 Go to Table of Contents
Table 6.2-G: Minimum Size of Water Meters, Mains, and Distribution Piping
based on water-supply fixture-unit (w.s.f.u) values
3/4 3/4 9.5 9.5 9.5 9.5 7.5 6 5 4.5 3.5 3
3/4 1 .5 15.5 11.5 9.5
1 1 32 32 32 32 32 28 28 17 12 9.5
3/4 1-1/4 32 32 32 32 32 32 32 32 32 30
1 1-1/4 80 80 80 80 80 80 69 60 46 36
1-1/2 1-1/4 80 80 80 80 80 80 76 65 50 38
1 1-1/2 87 87 87 87 87 87 87 87 87 84
1-1/2 1-1/2 151 151 151 151 151 151 151 144 114 94
2 1-1/2 151 151 151 151 151 151 151 151 118 97
1 2 87 87 87 87 87 87 87 87 87 87
1-1/2 2 275 275 275 275 275 275 275 275 275 252
2 2 365 368 368 368 368 368 368 368 318 273
2 2-1/2 533 533 533 533 533 533 533 533 533 533
Notes:
[1] Minimum size of building supply is ¾-in. pipe.
[2] User shall follow the most recently adopted code; above table was the most recent version at the time of publication of t his Manual.
Source: 2021 International Plumbing Code – Table E201.1
Table 6.2-H: Water-supply fixture-unit (w.s.f.u) values for Various Plumbing
fixtures and Fixture Groups
Type of Fixtures or Group of Fixtures Load in w.s.f.u. values
HOT COLD COMBINED
Bathtub (with/without overhead shower head) 1.0 1.0 1.4
Clothes washer 1.0 1.0 1.4
Dishwasher 1.4 — 1.4
Full-bath group with bathtub (with/without shower head) or shower stall 1.5 2.7 3.6
Half-bath group (water closet and lavatory) 0.5 2.5 2.6
Section 6: Water and Wastewater Design Criteria
6.2 Water Design CriteriaGuidelines
6.2.9 Meters and Meters Cans/Vaults
Design Criteria Manuals 160
Published: July January 20264 Go to Table of Contents
Table 6.2-H: Water-supply fixture-unit (w.s.f.u) values for Various Plumbing
fixtures and Fixture Groups
Hose bibb (sillcock)1 — 2.5 2.5
Kitchen group (dishwasher and sink with/without garbage grinder) 1.9 1.0 2.5
Kitchen sink 1.0 1.0 1.4
Laundry group (clothes washer standpipe and laundry tub) 1.8 1.8 2.5
Laundry tub 1.0 1.0 1.4
Lavatory 0.5 0.5 0.7
Shower stall 1.0 1.0 1.4
Water closet (tank type) — 2.2 2.2
Notes:
[1] The fixture unit value 2.5 assumes a flow demand of 2.5 GPM, such as for an individual lawn sprinkler device. If a hose bibb/sill cock
will be required to furnish a greater flow, the equivalent fixture-unit value may be obtained from this table or Table P2903.6(1).
[2] Supply loads in the building water-distribution system shall be determined by total load on the pipe being sized, in terms of w.s.f.u.,
as shown in Table P2903.6, and gallons per minute (GPM) flow rates [Ssee Table P2903.6(1)]. For fixtures not listed, choose a w.s.f.u.
value of a fixture with similar flow characteristics.
[3] For SI units: 1 GPM = 3.785 Liters per minute (L/m).
[4] User shall follow the most recently adopted code. The above table was the most recent version at the time of publication of this
Manual.
Source: 2021 International Residential Code – Table P2903.6
Table 6.2-I: Load Values assigned to Fixtures 1
Fixture Occupancy Type of Supply
Control Load in w.s.f.u values
COLD HOT COMBINED
Bathroom group Private Flush tank 2.7 1.5 3.6
Bathroom group Private Flushometer-valve 6.0 3.0 8.0
Section 6: Water and Wastewater Design Criteria
6.2 Water Design CriteriaGuidelines
6.2.9 Meters and Meters Cans/Vaults
Design Criteria Manuals 161
Published: July January 20264 Go to Table of Contents
Table 6.2-I: Load Values assigned to Fixtures 1
Bathtub Private Faucet 1.0 1.0 1.4
Bathtub Public Faucet 3.0 3.0 4.0
Bidet Private Faucet 1.5 1.5 2.0
Combination fixture Private Faucet 2.25 2.25 3.0
Dishwashing machine Private Automatic — 1.4 1.4
Drinking fountain Offices, etc. ⅜-in. valve 0.25 — 0.25
Kitchen sink Private Faucet 1.0 1.0 1.4
Kitchen sink Hotel, restaurant Faucet 3.0 3.0 4.0
Laundry trays (1 to 3) Private Faucet 1.0 1.0 1.4
Lavatory Private Faucet 0.5 0.5 0.7
Lavatory Public Faucet 1.5 1.5 2.0
Service sink Offices, etc. Faucet 2.25 2.25 3.0
Shower head Public Mixing valve 3.0 3.0 4.0
Shower head Private Mixing valve 1.0 1.0 1.4
Urinal Public 1-in. flushometer-valve 10.0 — 10.0
Urinal Public ¾-in. flushometer-valve 5.0 — 5.0
Urinal Public Flush tank 3.0 — 3.0
Washing machine (8-lb.) Private Automatic 1.0 1.0 1.4
Washing machine (8-lb.) Public Automatic 2.25 2.25 3.0
Washing machine (15-lb.) Public Automatic 3.0 3.0 4.0
Water closet Private Flushometer valve 6.0 — 6.0
Water closet Private Flush tank 2.2 — 2.2
Water closet Public Flushometer valve 10.0 — 10.0
Water closet Public Flush tank 5.0 — 5.0
Water closet Public or private Flushometer tank 2.0 — 2.0
Notes:
[1] For fixtures not listed, loads should be assumed by comparing the fixture to one listed using water in similar quantities and at similar
rates. The assigned loads for fixtures with both hot and cold water supplies are given for separate hot and cold water loads and for
total load. The separate hot and cold water loads are three-fourths of the total load for the fixture in each case.
[3] For SI units: 1 inch = 25.4 mm, 1 pound = 0.454 kg.
[4] User shall follow the most recently adopted code. The above table was the most recent version at the time of publication of this
Manual.
Source: 2021 International Plumbing Code – Table E103.3(2)
Table 6.2-J: Sample w.s.f.u Tabulation
Fixture Quantity
Load Values,
in Total w.s.f.u
(each)
Total
Fixture Units
Water Closet (Public; Flush Valve) 9 10.0 90
Water Closet (Public; Flush Tank) 3 5.0 15
Urinal (Public; ¾-in. Flush Valve) 5 5.0 25
Section 6: Water and Wastewater Design Criteria
6.2 Water Design CriteriaGuidelines
6.2.9 Meters and Meters Cans/Vaults
Design Criteria Manuals 162
Published: July January 20264 Go to Table of Contents
Table 6.2-J: Sample w.s.f.u Tabulation
Lavatory (Public) 10 2.0 20
Kitchen Sink (Hotel, Restaurant) 2 4.0 8
Service Sink 1 3.0 3
Shower Head (Private) 1 1.4 1.4
Total 162.4
Table 6.2-K: Land Use and Service Units/SFE Equivalencies
Meter Type Meter Size Typical Land Use
Single-Family
Equivalents
(SFEs)
Positive Displacement ⅝-in. x ¾-in. Residential – Single-Family
(Building less than 1,300 sq. ft. per lot size less than 6,000 sq. ft.) 0.5
Positive Displacement ⅝-in. x ¾-in. Residential – Single-Family 1.0
Positive Displacement ¾-in. x ¾-in. Residential / Commercial 1.5
Positive Displacement 1-in. Residential / Commercial 2.5
Positive Displacement 1½-in. Commercial 5.0
Positive Displacement 2-in. Commercial 8.0
Compound 3-in. Commercial / Industrial 22.5
Compound 4-in. Commercial / Industrial 50.0
Notes:
[1] The total service units for multifamily apartment projects with eight (8) or more units shall be determined by multiplying the total
number of bedrooms in the multifamily apartment project by 0.26 Single-Family Equivalents (SFEs).
Source: City of Denton Approved Meter Manufacturer’s Specifications;
City of Denton Code of Ordinances Section 26-218 - Water and Wastewater Facilities - Exhibit F
C. Location
Water meters and meter cans and vaults shall be placed within a City ROW, Public Utility Easement
or Public Water Easement. Placement shall also satisfy the following requirements:
1. Located as close as possible to the public water main;
2. Easily accessible to City of Denton employees; and
3. Located in an unpaved area that does not conflict with vehicular or pedestrian traffic.
D. Furnishing and Installing
All meters two (2) inches and smaller, shall be furnished and installed by City Water Utilities for fees
per the current Fee Schedule. All meter assemblies three (3) inches and larger and their associated
vaults, shall be furnished and installed by Contractor at their expense and inspected by Public Works
Inspection and City Water Utilities.
E. Details
Details of the meter can assemblies for meter sizes two (2) inches and smaller are shown in the City
of Denton Standard Details.
Details of the meter vault assemblies for meter sizes three (3) inches and larger are shown in the
City of Denton Standard Details.
Section 6: Water and Wastewater Design Criteria
6.2 Water Design CriteriaGuidelines
6.2.10 Underground Utility Crossing
Design Criteria Manuals 163
Published: July January 20264 Go to Table of Contents
F. Backflow Prevention
Note that this section of the DCM, 6.2.59.(F)-Backflow Prevention will be superseded and void upon
the adoption of a formal City Ordinance governing backflow prevention assembly requirements..
Backflow Prevention Assemblies are required in accordance with the International Plumbing Code,
2021 IFC, 30 TAC § 290.44. Backflow Prevention Assemblies must be utilized as follows:.:
1. At each dedicated fire line connection. A flanged fire line valve shall be required to connect
to the tee located on the main line and a fire line valve shall be required outside the
downstream side of the vault or ROW line whichever applies;
2. After each meter of any site served by redundant domestic meters;
3. At facilities supporting Recreational Vehicle (RV) connections for the purpose of flushing
waste tanks;
4. At all services outside City limits, in accordance with 30 TAC § 290.47(f)); and
5. At all properties that have an auxiliary water source. These properties must protect
connections to the public water system using a reduced pressure backflow assembly (RPBA).
Backflow prevention devices shall be placed at the ROW or an easement line adjacent to the
connection to the public water system.
6.2.96.2.10 Underground Utility Crossing
Water mains shall be separated from wastewater mains as set forth in 30 TAC § 290.44(e) - Location of
Waterlines, as amended.
Where water mains are laid under or over another buried utility line or underground facility (i.e., storm drain,
culvert boxes, franchise utilities, etc.), special requirements may be necessary for the protection of the water
main. Table 6.2-L provides requirements for different crossing situations. This table is not a replacement for
separation requirements for sewer and water lines as governed by 30 TAC §§ 217.53 and 290.44, respectively.
Table 6.2-L: Utility Crossing Requirements
Water Utility Crossing Utility Line Size (in.) Separation
(feet) Special Requirement
New/existing Water Under < 24 ≥ 2 None
New/existing Sewer Under < 24 ≥ 2 None
New/existing Water Under 24 to 42 ≥ 2 None
New/existing Sewer Under 24 to 42 ≥ 2 None
Section 6: Water and Wastewater Design Criteria
6.2 Water Design CriteriaGuidelines
6.2.11 Fence or Wall Crossings
Design Criteria Manuals 164
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Table 6.2-L: Utility Crossing Requirements
New Water Under > 42 ≥ 2 Encased in 150±psi pressure class pipe
Existing Water Under > 42 ≥ 2 Encased in split steel casing
New Sewer Under > 42 ≥ 2 Encased in 150±psi pressure class pipe
Existing Sewer Under > 42 ≥ 2 Encased in split steel casing
New Water Under ≥ 10 ≥ 2 Cased in steel pipe
Existing Water Under ≥ 10 ≥ 2 Cased in split steel pipe
New Sewer Under ≥ 10 ≥ 2 Cased in steel pipe
Existing Sewer Under ≥ 10 ≥ 2 Cased in split steel pipe
New/existing Water Over < 24 ≥ 2 None
New/existing Sewer Over < 24 ≥ 2 None
New/existing Water Over ≥ 24 ≥ 2 None
New/existing Sewer Over ≥ 24 ≥ 2 None
A. To minimize crossing impacts, crossings must be perpendicular, if possible.
B. Utility crossings with less than two (2) feet of separation require a design deviation request (which
will include special requirements) after providing a thorough analysis detailing physical and
economic factors involved.
C. Pursuant to the Code of the City of Denton, Texas, Chapter 25, Article II, Sec. 25-80-Facility Size
and Locations, all ROW user facilities are required to maintain a minimum separation of 24 inches
from all City utility system facilities. If a ROW user may encounter a hardship due to this
requirement, the ROW user may request a design deviation as detailed in Section 8 of this Manual.
D. Split-steel casing shall follow sizing requirements of pressure-rated casing.
E. See City Standard Specification Section 33 05 07 Steel Casing Pipe.
F. Casing spacers shall be placed not more than five (5) feet apart.
G. Encasement shall be extended a minimum of three (3) feet beyond the edge of the utility or facility
to be crossed. Water mains that cross utility lines in private easements must adhere to the
requirements of the easement owner, as well as those listed above.
6.2.106.2.11 Fence or Wall Crossings
A. Water mains should be routed to avoid entering private property. In circumstances where it is
impractical to avoid doing so, provisions are required to allow City staff to inspect, maintain , and
repair its infrastructure. Water mains crossing fences will require a design deviation request as per
Section 8 of this Manual, to be reviewed by the City’s Engineer, after thorough consideration of the
physical and economic factors involved. Design deviations may require additional provisions
beyond this Manual.
B. Water mains crossing under privacy fencing (wood, chain -link, or plastic) shall not require any
special protection.
C. Water mains crossing under other types of fencing will require the fence to be constructed of easily
removable panels or have gates that can be removed from the easement.
D. Water mains may not cross under retaining walls.
Section 6: Water and Wastewater Design Criteria
6.2 Water Design CriteriaGuidelines
6.2.16 Highway Non-City Road Crossings
Design Criteria Manuals 165
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E. There must be at least two (2) feet of vertical separation between a water line and any utility or
storm drain crossing it.
6.2.116.2.12 Highway Non-City Road Crossings
Crossings of State or County-controlled roads shall require the review and approval of the appropriate
regulatory agency after consultation with the City’s Engineer regarding crossing location. Crossings shall
meet the requirements provided by the controlling agency and by the City of Denton Standards. In the
event of different requirement levels for the same item, the more stringent standard shall apply. Crossing
locations must be easily and directly accessible on each side of the highwaysuch roads. Additional access
easements and installation of all-weather road surface may be required. The City of Denton shall have final
say in the location, criteria and standards of highway crossings considering access, maintenance and repairs.
6.2.126.2.13 Railroad Crossings
The design engineer shall, prior to the design of any railroad crossing, contact the appropriate railroad
company and regulatory agency to determine if there are any special requirements. Crossings shall be
discussed with and must be approved in writing by the City’s Engineer . In the event the City of Denton
Design Criteria are more stringent than those of the Railroad Company or regulatory agency, the City’s
standards shall apply. Crossing locations must be easily and directly accessible on each side of the railroad.
Additional access easements and installation of all-weather road surface may be required. The City of
Denton shall have final say in the location, criteria and standards of railraodrailroad crossings considering
access, maintenance and repairs.
6.2.136.2.14 Creek Crossings
Where a water main is laid under any flowing stream or semi-permanent body of water, such as a marsh or
pond, or an identified ESA (See DDC 7.4) the water main shall be installed in a separate watertight
encasement pipe, with valves on each side of the crossing to allow for the isolation and testing of that
portion of the water main to determine if there are any leaks , and to facilitate future repairs after
consultation with the City’s Engineer.
A primary consideration in the design of creek crossings is the prevention of soil erosion in the areas of
trench backfill. The design engineer shall determine the need and limits of any special embedment , and
determine and specify the limits for specialized backfills. Crossing locations must be easily and directly
accessible on each side of the creek. Additional access easements and installation of all-weather road
surface may be required. The City of Denton shall have final say in the location, criteria and standards of
creek crossings considering access, maintenance and repairs.
6.2.146.2.15 Elevated Crossings
Elevated crossings are not permitted for water mains except for special cases approved by the City’s
Engineer. Design requirements for approved elevated crossings shall be tailored to the specific project
characteristics.
6.2.156.2.16 Tunneling, Boring, Jacking and Casing
Tunneling, boring, jacking and casing are methods used for water line placement under restrictive
conditions when open-cut construction is not allowed. Only straight pipe alignments for both horizontal
and vertical alignment are allowed.
Section 6: Water and Wastewater Design Criteria
6.2 Water Design CriteriaGuidelines
6.2.17 Existing Water Main Replacement
Design Criteria Manuals 166
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Design engineers should consider the location, size, and depth of boring, tunnelling, and receiving pits
when choosing the beginning and ending stations for boring or tunnelling. A typical bore pit is between 35
and 40 feet in length to accommodate the boring machine and one (1) joint of pipe. Width of the bore pit
can vary depending on the depth and size of pipe, with the narrowest width being approximately 15 feet.
Tunnelling pits can vary greatly in size depending on the depth and size of the tunnel to be excavated.
Additional size and spacing requirements may be required as outlined in DDC 7.4 when working adjacent
to confirmed ESAs. The preferred location for the bore or tunnel pit is the lower elevation end of the bore
or tunnel; allowing any groundwater and/or boring slurry to drain from the tunnel into the bore or tunnel
pit. The water can then be removed by pumping.
A. Steel casing pipe, where required for open-cut or other than open-cut installation, shall conform
to the City Standard Specification 33 05 07 Steel Casing Pipe, and be subject to the following
guidelines:
1. Within Railroad ROW – the casing pipe size shall be sufficient to accommodate the outside
diameter (OD) of the carrier pipe bell of at least one City standard size greater than what is
required (See 6.2.4.B). Additionally, the casing pipe size must accommodate any external joint
restraint fittings required to restrain the carrier pipe. The annular space between the carrier
pipe and casing pipe shall not be grouted.
2. All other situations – the casing pipe size shall be sufficient to accommodate the OD of the
carrier pipe bell plus an additional four (4) inches of clear space. The carrier pipe shall be
restrained through grout applied to the annular space between the casing and carrier pipe
so external pipe restraints are not required.
B. Carrier pipes through casing shall be restrained as follows:
1. Segmented PVC and DIP shall be restrained with either external restraint fittings applied to
push-on bell and spigot pipe or by utilizing manufactured restrained joint pipe.
2. HDPE shall be restrained through fused joints.
3. Concrete steel cylinder pipe shall be restrained through welded joints.
All carrier pipes shall be supported with approved spacers and casing end seals. Refer to City of Denton
Standard Detail U208A and the current City approved Materials Submittal List.
Large diameter (48 inches or greater) or long length bores or tunnels (200 feet or greater) may require
tunnel liner plate instead of steel casing. These situations shall require design calculations to identify the
type and gage of tunnel liner plate to be utilized per Specification 33 05 08 Tunnel Liner Plate.
6.2.166.2.17 Existing Water Main Replacement
A. Whenever an existing main is to be replaced by a new main, use the following guidelines for
alignment and design:
1. The new line should be located as near as possible to the existing line; while allowing the
existing line to remain in service, until the new line is ready to be put into service.
2. If the existing line is in or next to a roadway, the new line should be placed under existing
pavement, not behind the curb in the parkway area.
3. The new line should be designed to utilize the existing metering locations where possible.
B. The size of the new line should match the size of the existing line. If the existing line is a non -
Section 6: Water and Wastewater Design Criteria
6.2 Water Design CriteriaGuidelines
6.2.19 Requirements for Abandoning Water Mains
Design Criteria Manuals 167
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standard size (i.e., 6-in. or 10-in.) then the new line should be sized for the next larger standard size.
The design engineer shall perform field investigations to determine pavement condition over the
existing main. The pavement may have been patched due to breaks in the existing main over the
years. Based on field investigations, the design engineer shall include additional quantities for
pavement replacement, if necessary.
6.2.176.2.18 Requirements for Abandoning Water Mains
The design engineer should note the limits and appropriate conditions for the abandoning of existing water
mains which are to be replaced by the construction of any proposed water mains.
The design engineer should also make allowances in the design to provide for the existing and proposed
mains to be in service simultaneously, until all customer services are transferred from the old main to the
new main with minimum interruption of service. If the construction of a proposed main necessitates the
abandoning of the existing main prior to the new main’s placement into service, th en provisions for a
temporary water main with services must be addressed by the design.
A. Typically, abandoned lines may be left in place with only the ends being plugged with grout
or concrete. However, the City may require special abandonment actions including, but not
limited to, filling the abandoned water main with grout, removal and prope r disposal of all
above ground appurtenances, and removal and proper disposal of the abandoned
pipe.Replacement Mains
On occasions when connecting to an existing main, it may be desirable to have an additional valve
on the existing main. In this situation, the design engineer should consider using a cut-in
connection with a tee and valve being cut into the existing main. See Figure 3.4 in Drawing PIAZ14
of the City of Denton Standard Details.
B. Extension Mains
A new valve shall be installed at the point of connection for water main extensions. This will
facilitate the testing and chlorination of the new main prior to its placement into service. See Figure
3.5 in Drawing PIAZ14 the City of Denton Standard Details.
C. Fire Hydrants
A new valve shall be installed at the point of connection for water main extensions. This will facilitate
the testing and chlorination of the new main prior to its placement into service. See Figure 3.5 in
Drawing PIAZ14 the City of Denton Standard Details.
6.2.19 Water Treatment Plants, Ground Storage Tanks, Elevated Storage TanksESTs,
Pressure Tanks, and Booster Pump Stations
If new public water treatment plants (WTPs), ground storage tanks (GSTs), elevated storage tanks (ESTs),
pressure tanks and/or Booster Pump Stations are needed to support a development, the design shall be
directed by the Water Utility considering the needs of the development and the Water Utility System.
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design GuidelinesCriteria
6.3.1 Estimated Wastewater Flows
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6.3 Wastewater Design GuidelinesCriteria
6.3.1 Estimated Wastewater Flows
For sewers in new developments, sewer lines and lift stations shall be designed to accommodate the
projected buildout flows from all residential, commercial, industrial, or institutional sources upstream of the
proposed sewer improvement. Figure: 30 TAC § 217.32(a)(3) Table B.1. - Design Organic Loadings and Flows
for a New Wastewater Treatment Facility (Ssee excerpted information in Table 6.3-A) shall be used as a
guide to generate wastewater flows. However, minimum flow capacity for sizing of sewers for peak flow
condition shall not be less than the results of the following calculation procedures:
A. Delineate the wastewater drainage area that will drain into the sewer main or lift station. Include
all upstream offsite areas.
B. For the development site, use the following design parameters:
1. Table 6.3-A to generate the wastewater loading by type of use.
2. 3.2 capita per lot for single-family.
3. 2.5 capita per unit for multifamily.
4. Apply a 4.0 multiplier to the average daily flow to determine the peak flow.
C. For undeveloped upstream areas, use the following design parameters:
1. 4 lots per acre.
2. 3.2 capita per lot.
3. Average daily flow of 90 GPCD.
4. Apply a 4.0 multiplier to the average daily flow to determine the peak flow.
D. For developed residential upstream areas, use the following design parameters:
1. Count number of single-family lots.
2. Obtain number of multifamily units (available through DCAD)
3. 3.2 capita per lot for single-family.
4. 2.5 capita per unit for multifamily.
5. Average daily flow of 90 GPCD
6. Apply a 4.0 multiplier to the average daily flow to determine the peak flow
E. For developed non-residential upstream areas, use the following design parameters:
1. Average daily flow of 1,500 GPD per acre.
2. Apply a 4.0 multiplier to the average daily flow to determine the peak flow.
For replacement of existing sewers and construction of parallel sewers for additional capacity, wastewater
flow data may be provided by the City from data generated by City sewershed computer models. The cost
for modeling a project’s impact with the City’s collection system model will be the responsibility of the
developer and paid to the City.
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design GuidelinesCriteria
6.3.2 Size and Slope of Sewers
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Proposed impacts to the City’s system determined to, or likely to, cause (through hydraulic modeling or
other analysis) these limits to be exceeded, are prohibited without additional improvements to the public
system to address the capacity deficiencyso the system can be operated within these parameters.
Table 6.3-A: Design Flows for a New Wastewater Treatment Facility
Source Remarks Daily Wastewater Flow
(Gal. per person)1
Municipality Residential 75 - 100
Subdivision Residential 75 - 100
Trailer Park 2 (Transient) 2½ Persons per Trailer 50 - 60
Mobile Home Park 2 3 Persons per Trailer 50 - 75
School Cafeteria & Showers
Cafeteria/ No Showers
20
15
Recreational Parks Overnight User
Day User
30
5
Office Building or Factory Facility must be designed for the largest shift 20
Hotel/Motel Per Bed 50 - 75
Restaurant Per Meal 7 - 10
Restaurant with bar or cocktail lounge Per Meal 9 - 12
Hospital Per Bed 200
Nursing Home Per Bed 75 - 100
Alternative Collection Systems, e.g., septic tanks Per Capita 75
Notes:
[1] City of Denton requires usage of the highest number of the TCEQ ranges.
[2] At the time of updating this Manual, the TCEQ is evaluating criteria for tiny homes, and should be consulted as appropriate.
Source: TCEQ Rules - 30 TAC §217.32(a)(3), Table B.1
6.3.2 Size and Slope of Sewers
After the design engineer has determined the wastewater flows per Section 6.3.1 of this Manual, the sewer
size can be determined using the following criteria. However, no sewer, other than service laterals and force
mains, shall be less than eight (8) inches in diameter.
The size and grade of the proposed sewer shall be evaluated using Manning’s formula
V= 1.49/n (R) 0.67 (S) 0.50 [Eqn. 6.1]
Where: V = velocity (in fps)
n = Manning’s coefficient of roughness; minimum 0.013
R = hydraulic radius (feet)
S = slope of energy grade line (feet per foot)
Proposed sewers shall be designed with slopes sufficient for velocity of three (3.0) fps, with a minimum
required velocity of two (2.0) fps. The minimum acceptable Manning’s “n” factor for design shall be 0.013,
which takes into consideration the slime, grit and grease layers that will affect hydraulics or hinder flow as
the pipe matures. The sewer pipe grades shown in Table 6.3-B are based on an “n” value of 0.013 and are
the minimum acceptable slope for sewer lines.
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design GuidelinesCriteria
6.3.3 Sewer Alignment
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Table 6.3-B: Minimum and Maximum Pipe Slopes
Size of Pipe - ID
(inches)
Minimum Slope
(%)
Maximum Slope
(%)
Capacity Flowing Full at
Min. Slope (MGD)
8 0.335 8.40 0.45
10 0.25 6.23 0.71
12 0.20 4.88 1.03
15 0.15 3.62 1.62
18 0.115 2.83 2.25
21 0.095 2.30 3.07
24 0.08 1.93 4.14
7 0.07 1.65 4.91
30 0.06 1.43 6.23
33 0.055 1.26 7.66
36 0.045 1.12 9.17
The capacity of the sewer pipe flowing full shall be computed by the following equation:
C = 0.299/n (D) 2.67 (S) 0.50 [Eqn. 6.2]
Where: C = capacity (million gallons per day-MGD)
n = Manning’s coefficient of roughness; minimum 0.013
D = inside diameter (feet)
S = slope of the energy grade line (feet per foot)
Sewer mains shall be designed to convey peak flow at no more than 80% of full pipe capacity at system
buildout.
A. High Velocity Protection
Where velocities greater than 10 fps will occur when a pipe flows full, based on Manning’s Equation
and an “n” value of 0.013, restrained joint pipe or external restraint systems must be utilized.
6.3.3 Sewer Alignment
Design engineers shall be guided by the following in the alignment of wastewater lines:
A. Collection system extensions must follow topographical depressions and extend to the upstream
drainage shed, considering storm drainage improvements. Crossing into other drainage sheds
require written approval from City’s Engineer;
A.B. For new construction in areas not served, sewer mains shall be laid straight between manholes. No
horizontal or vertical bends are allowed between manholes;
B.C. Avoid shifting mains from one side of the ROW to the other side of the ROW between street
intersections;
C.D. Where the bypass of existing flows is feasible, it is recommended that replacement mains be
constructed horizontally in the same trench; and
E. Except for pipe crossings, no franchise utility shall be installed within five (5) feet of a sewer main;
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design GuidelinesCriteria
1.1.1 Sewer Main Depth and Recommended Cover
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and
D.F. Vertically parallel wastewater mains require written approval from the City’s Engineer. Details
regarding main access must be planned out including but not limited to the dedicated of easements
or City ROW to ensure ability to access the mains, calculation s and details showing distances from
the main that other utilities may not be placed to preserve ability to access ..
E.
6.3.4 Sewer Main Depth and Recommended Cover
A. Minimum depth for the design of sewer mains shall be determined by providing a 2% grade for the
lateral from the center of the house or building to the center of the proposed main and including
an additional two (2) feet drop. Therefore, for a house 100 feet from the proposed sewer main, the
designed depth of the main shall be at least four (4) feet below the FFE of the house since:
2 feet + (2% of 100 feet) = 4 feet [Eqn. 6.3]
The lateral also must have at least two (2) feet of cover at its shallowest point. The design engineer
is responsible for ensuring sufficient depth and grade is maintained to serve all building sites in the
sewer shed.
B. The maximum depth of sewer mains is 30 feet.Recommended cover for all sewer mains is four (4)
feet to six (6) feet. Minimum cover shall be three (3) feet and six (6) inches or 3-½ feet. Any main
approved via a Design Deviation to have less than minimum cover shall be encased in Class “B”
embedment per City Standard Specifications. See Drawing U204 of the City of Denton Standard
Details.
When establishing depth for proposed wastewater mains, design engineers shall consider the
impact of proposed water and drainage improvements especially on service laterals that cross those
improvements to connect to the wastewater main.
The maximum depth of sewer mains is 30 feet.
C.
6.3.5 Recommended Cover
Recommended cover for all sewer mains is four (4) feet to six (6) feet. Minimum cover shall be three (3)
feet and six (6) inches or 3-½ feet. Any main approved to have less than minimum cover shall be encased
in Class “B” embedment per City Standard Specifications. See Drawing U204 of the City of Denton Standard
Details.
When establishing depth for proposed wastewater mains, design engineers shall consider the impact of
proposed water and drainage improvements especially on service laterals that cross those improvements
to connect to the wastewater main.
6.3.6 Sewer Laterals
A. Water Utilities, Field Operations, or Engineering and Planning staff reserve the right to permit utility-
supervised connections to the collection system by non-City staff. Note that the developer will be
responsible for all surface rehabilitation associated with connecting to the City’s Water Utilities.
Surface rehabilitation must match existing site conditions or better.
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design GuidelinesCriteria
6.3.5 Gravity and Force Main Sewer Pipe Material
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B. Laterals may not serve more than one (1) lot.
C. Minimum lateral sizes from the sewer main to the public cleanout are:
1. 4-in. minimum for single-family
2. 6-in. minimum for residential duplex, triplex, and quadplex
3. 6-in. minimum for local retail, light commercial, apartment, manufacturing and industrial
D. Single-way clean-outs shall be provided on laterals at the public easement or ROW line. Double-
way cleanouts are not allowed. See Drawings S403 and S404 of the City of Denton Standard Details.
E. Manholes shall be provided for lateral connections when the lateral pipe diameter is equal to the
main sewer pipe diameter or if the lateral is eight (8) inches in diameter or larger.
F. Laterals shall be constructed to the property line and shall be located at a point five (5) feet
downstream from the center of the lot on unimproved property. For improved property, design
engineers should use technical judgement in lateral placement.
G. Preferred grade for lateral construction within the ROW/PUE is 2%. Laterals within ROW/PUE shall
not be designed with less than 1% grade.
6.3.76.3.5 Gravity and Force Main Sewer Pipe Material
Gravity and Force Main sewer pipe shall meet the following criteria unless special circumstances require an
alternative and is approved by the City’s Engineer. Slope of grade across cover shall be a maximum of 4H:1V.
Table 6.3-C: Minimum and Maximum Pipe Slopes
Pipe Diameter Application Pipe Material
8-in. to 12-in. Gravity PVC – ASTM D3034, SDR 26; HDPE – ASTM D3350, DR-17
15-in. Gravity PVC – ASTM D3034, SDR 26
18-in. to 24-in. Gravity PVC – ASTM F 679, PS115; Fiberglass Reinforced Plastic – ASTM D3262
6-in. to 60-in. Force Main HDPE – ASTM D3350, DR-13.5;
DIP – AWWA C150/C151, CL52 or PC 350, epoxy interior lining
A. For gravity sewer pipe sizes over 24 inches in diameter, design calculations and pipe selection shall
be submitted by the development design engineer for review. Approvals will be provided on a
project specific basis.
B. Force main sewer pipe shall be designed to meet the working and surge pressure requirements of
the specific application. Design calculations and pipe selection shall be submitted by the
development design engineer for review.
C. Different pipe materials shall not be mixed between manholes. If it is anticipated that a mixing of
materials will occur, the design engineer shall design a manhole at the point of transition of pipe
materials. For previously placed stub-out of a material other than PVC pipe, design engineer shall
add a note to the plans calling for removal of the stub-out or change the material of the proposed
pipe for that section of pipe between manholes.
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design GuidelinesCriteria
6.3.7 Sewer Pipe Embedment
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6.3.86.3.6 Sewer Pipe Embedment
The types of embedment and backfill for sewer mains are shown in Drawings U201, U202, U203A , and
U203C of the City of Denton Standard Details. Embedment requirements shall be based on sewer mains
under proposed pavement, unpaved areas and existing pavement.
6.3.96.3.7 Manholes
Manholes constructed on existing or proposed sewer lines shall be sized as follows:
Table 6.3-D: Manhole Sizing
Pipe Diameter Manhole Diameter
8-in. to 12-in. 4.0 feet (For depths greater than 12 feet, use 5.0 feet)
15-in. to 27-in. 5.0 feet
30-in. to 36-in. 6.0 feet
Notes:
[1] Special manholes shall be designed for mains larger than 36-in. diameter pipe.
The types of manholes allowed by the City are shown in Drawings S101, S102, S103 , and S107B of the City
of Denton Standard Details. Additionally, connections to manholes must comply with City Standard
Specifications.
Generally, manholes shall be stationed on the main run, and where known, the stations of the side mains
should also be indicated. When connecting a proposed main to an existing main at a manhole, the
connection shall have the top inside elevation of the outfall main level with the top inside elevation of the
proposed main. Connections to brick manholes are prohibited.
At the discretion of Water Utilities, Field Operations, or Planning and Engineering Departmentivision staff,
manholes with known deficiencies will be required to be replaced.
Manholes deeper than 20 feet must be of monolithic construction, such as FRP.Glass-fiber Reinforced
Polyester.
A. Manhole Locations
Manholes shall be provided at the following locations to facilitate maintenance, cleaning, and
inspection:
1. At the location of lateral connections that are 8-in. diameter or larger;
2. At 500 feet intervals on sewer mains 15-in. diameter or smaller; at 800 feet internals on mains
18-in. diameter through 30-in. diameter; at 1,000 feet intervals on mains 36-in. diameter
through 48-in. diameter; and at 2,000 feet intervals for 54-in. diameter and larger;
3. At all locations where pipe diameter or pipe material changes;
4. At all locations where the horizontal or vertical alignment of the sewer main changes;
5. At the ends of all mains with service connections. Two main upstream ends may not be
combined in one manhole;
6. At the end of any pipe segment at least 150 feet long;
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design GuidelinesCriteria
6.3.10 Sewer Laterals
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7. At the end of every end-of-line (EOL);
8. Sewer service laterals are to be connected to the sewer main line and not into a manhole
unless it is a size-on-size connection;
9. Manholes shall not be placed in sidewalks, pedestrian ramps, driveway approaches, or in the
bottom or on the slopes of a drainage channel or drainage structure;
10. At a minimum of 40 feet from any railroad track; and
11. Separation of utilities around manholes shall be a minimum distance of five (5) feet , to allow
for maintenance and repair.
6.3.8 Sewer Laterals
B. Water Utilities, Field Operations, or Engineering and Planning staff reserve the right to permit utility-
supervised connections to the collection system by non-City staff. Note that the developer will be
responsible for all surface rehabilitation associated with connecting to the City’s Water Utilities.
Surface rehabilitation must match existing site conditions or better.
C. Laterals may not serve more than one (1) lot.
D. Minimum lateral sizes from the sewer main to the public cleanout are as follows:
1. For single-family: four (4) inches
2. For residential duplex, triplex, and quadplex: six (6) inches
3. For local retail, light commercial, apartment, manufacturing and industrial: six (6) inches.
E. Single-way clean-outs shall be provided on laterals at the public easement or ROW line. Double-
way cleanouts are not allowed. See Drawings S403 and S404 of the City of Denton Standard Details.
F. Manholes shall be provided for lateral connections when the lateral pipe diameter is equal to the
main sewer pipe diameter or if the lateral is eight (8) inches in diameter or larger.
G. Laterals shall be constructed to the property line and shall be located at a point five (5) feet
downstream from the center of the lot on unimproved property. For improved property, design
engineers should use technical judgement in lateral placement.
B.H. Preferred grade for lateral construction within the ROW/PUE is 2%. Laterals within ROW/PUE shall
not be designed with less than 1% grade.
6.3.106.3.9 Underground Utility Crossings
Wastewater mains and manholes shall be separated from water mains as set forth in 30 TAC §217.53 (d) -
Separation Distances and 30 TAC §290.44 - Water Distribution.
The requirements of Section 6.2.10 of this Manual shall govern the crossing of underground utility lines by
wastewater mains.
6.3.10 Fence or Wall Crossings
The requirements of Section 6.2.11 of this Manual shall govern the crossing of fences or walls by wastewater
mains.
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6.3.11 Non-City RoadHighway Crossings
Crossings of State or County-controlled roads shall require the review and approval of the appropriate
regulatory agency after consultation with the City’s Engineer regarding crossing location. Crossings shall
meet the requirements provided by the controlling agency and by the City of Denton Standards. In the
event of different requirement levels for the same item, the more stringent standard shall apply. Crossing
locations must be easily and directly accessible on each side of the highwaysuch roads. Additional access
easements and installation of all-weather road surface may be required. The City of Denton shall have final
say in the location, criteria and standards of highway crossings considering access, maintenance and
repairs.Crossings of State or County-controlled roads shall require the review and approval of the
appropriate regulatory agency. Crossings shall meet the requirements made by the controlling agency and
by City of Denton Standards. In the event of different requirement levels for the same item, the more
stringent standard shall apply.
6.3.12 Railroad Crossings
The design engineer shall, prior to the design of any railroad crossing, contact the appropriate railroad
company and regulatory agency to determine if there are any special requirements. Crossings shall be
discussed with must be approved in writing by the City’s Engineer. In the event the City of Denton Design
Criteria are more stringent than those of the Railroad Company or regulatory agency, the City’s standards
shall apply. Crossing locations must be easily and directly accessible on each side of the railroad. Additional
access easements and installation of all-weather road surface may be required. The City of Denton shall
have final say in the location, criteria, and standards of railroad crossings considering access, maintenance,
and repairs.The design engineer shall, prior to the design of any railroad crossing, contact the appropriate
railroad company and regulatory agency and determine if there are any special requirements. In the event
City of Denton Design Criteria are more stringent than those of the Railroad Company or regulatory agency,
the City’s standards shall apply.
6.3.13 Creek Crossings
When a sewer main crosses a creek or channel, the design engineer must evaluate the condition of the
creek bed and ensure erosion control is provided. Backfill material and minimum construction criteria are
shown in the City of Denton Standard Details S701 and S702. These criteria include creek bed soil and
condition, as well as presence of exposed rock. When working in these areas, minimize storage of soil,
materials, and equipment near floodways and waterways. Crossing locations must be easily and directly
accessible on each side of the creek. Additional access easements and installation of all-weather road
surface may be required. The City of Denton shall have final say in the location, criteria, and standards of
creek crossings considering access, maintenance and repairs.
A. Siphons
For creek or channel crossings where a Low-Water Channel Crossing is not feasible, design of an
inverted siphon crossing is permissible when approved by the City’s Engineer through a design
deviation request. Inverted siphons shall not have less than two (2) barrels, with a minimum pipe
size of eight (8) inches, and shall be provided with necessary appurtenances for convenient flushing
and maintenance. Access structures are required at each end of the siphon, with adequate
clearance for maintenance and cleaning purposes. Bank and channel stabilization may be required
to protect the crossing lines and casing of the carrier pipe may be required to meet environmental
or other restrictions. Siphon locations must be easily accessible on each side of the creek by heavy
equipment for maintenance. Additional access easements and installation of all-weather road
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surface may be required. The City of Denton shall have final say in the location, criteria, and
standards of creek crossings considering access, maintenance, and repairs.
6.3.14 Tunneling, Borings, Jacking, and Casing
Tunneling, boring, jacking and casing are methods used for sewer line placement under restrictive
conditions when open cut construction is not allowed. Only straight pipe alignments for both horizontal
and vertical alignments are allowed.
Design engineers should consider the location, size and depth of boring and receiving pits when
choosing the beginning and ending stations for boring. A typical bore pit is between 35 and 40 feet in
length to accommodate the boring machine and one joint of pipe. Width of the bore pit can vary
depending on the depth and size of pipe, with the narrowest width being approximately 15 feet. The
preferred location for the bore pit is the lower elevation end of the bore; allowing any groundwater
and/or boring slurry to drain from the tunnel into the bore pit. The water can then be removed by
pumping.
Steel casing pipe, where required for open-cut or other than open-cut installation, shall conform to City
Standard Specification 33 05 07 Steel Casing Pipe, and have an ID large enough to accommodate a
carrier pipe of at least two (2) standard sizes above the pipe being installed.
Force mains through casings tunnels and bores shall follow the same requirements as are laid out for water
mains in Section 6.2.16Error! Reference source not found. of this Manual.
6.3.146.3.15 Abandonment of Sewer Mains
A. The design engineer should note the limits and appropriate conditions for the abandoning of
existing wastewater mains which are to be replaced by the construction of any proposed
wastewater mains.
B. The design engineer should also make allowances in the design to provide for the existing and
proposed mains to be in service simultaneously until all customer services are transferred from the
old main to the new main with minimum interruption of service. If the construction of a proposed
main necessitates the abandoning of the existing main prior to the new main’s placement into
service, then provisions for a temporary wastewater main with services must be addressed by the
design.
C. Typically, abandoned lines may be left in place with only the ends being plugged with grout or
concrete. However, the City may require special abandonment actions including, but not limited to,
filling the abandoned wastewater main with grout, removal and proper disposal of all above ground
appurtenances, and removal and proper disposal of the abandoned pipe. In situations where a
manhole is being left in service even though one (1) or more lines into the manhole are being
abandoned, the abandoned line shall be cut and plugged outside of the manhole. However, if the
City determines that the pavement is in good condition the City may allow the abandoned line to
be plugged from inside of the manhole.
6.3.156.3.16 Abandonment of Manholes
If a manhole as well as the sewer main is to be abandoned, the method described in Abandonment of
Sewer Mains, above, along with the minimum guidelines shown in Drawing S105 of the City Standard
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Details, shall be used.
6.3.166.3.17 Lift Stations
The need to construct a lift station should be determined only after a thorough analysis of the physical and
economic factors involved. A Preliminary Engineering Report is required, which lists all factors and adheres
to current state regulations. The City reserves the right to review each proposal and determine whether
there is enough merit to justify a lift station. Any lift station located in the City of Denton CCN must adhere
to these requirements.
A. Preliminary Design Submittal
A preliminary design submittal is required for each lift station proposed. The submittal shall include
a written report and a map prepared by a Professional Engineer, licensed by the State of Texas.
1. The plans submitted shall contain the following information, at a minimum:
a. Be to scale, with the scale indicated;
b. A north arrow;
c. A location map;
d. Delineation of the boundary of the proposed development;
e. Delineation of the boundary of the sewershed in which the development lies ;
f. The area in acres of the development;
g. The area in acres of the sewershed contributing to the lift station;
h. The proposed land use or uses for the development;
i. The proposed land use or uses for the sewer basin;
j. The proposed lift station site, along with the GPS coordinates;
k. The proposed force main routing and size;
l. Delineation of the 100-year flood plain and ESAs;
m. Location and size of the existing collection system at the tie-in point;
n. Contour lines (2-ft. intervals);
o. Show how storm drainage is taken off site; and
p. Property lines.
2. The written report shall include the following information:
a. A general narrative about the proposed development and the circumstances that
warrant a lift station, including a phasing plan detailing the utilization and station
limitations from initial flow to buildout;;
b. Influent hydraulic calculations showing:
i. Area in acres of the sewer basin and the development;
ii. The area of each proposed land use for the development and for the projected
land use(s) for the basin;
iii. The design flow for the basin and the development;
iv. The peak flow for the basin and the development;
v. Elevation of the proposed lift station site; and
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vi. The elevation of the proposed discharge point of the force main.
c. Preliminary wet well volume calculations;
d. Preliminary force main size;
e. Cost estimates for proposed lift station(s) and force main(s), and cost estimates for a
gravity line in lieu of the lift station if possible;
f. Ground water levels included in a comprehensive geotechnical report for the in
proposed site areas; and
g. A copy of the summary transmittal letter to TCEQ showing agency approval of proposed
plans.
B. Site Layout
1. Station Siting:
The following are the minimum criteria for station sites:
a. The station shall be protected from the 100-year flood and shall be accessible during a
100-year flood;
b. The station should be located as remotely as possible from populated areas. The entire
station site shall be completely enclosed with an 8-ft. high, opaque concrete or masonry
wall, with an opaque sliding gate with a minimum width of 16 feet on track flush with
the ground. All shall be of an architectural style and colors blending with the
development architecture, as approved by the city;
c. The lift station site shall be large enough to allow the construction of the lift station to
serve the upstream basin(s), and its replacement while maintaining active service
without a bypass;.
b.d. The station site must have verified radio communication ability with the City’s central
Supervisory Control and Data Acquisition (SCADA) antenna location;
c.e. The station shall have a minimum 16-ft. wide drive approach and be accessible by City
of Denton service trucks, without requiring vehicles to turn after entering the drive
approach to the station;
d.f. The station will include an approved odor-control system;
e.g. The station site and its access shall be dedicated as a separate lot to the City, as City
property;
f.h. The station site cannot be located within the boundaries of any private entity intended
to regulate property including, but not limited to, HOAs, COAs, and POAs;
g.i. The station site shall be located so it may serve as much as the entire sewer basin as
possible. This may require the station to be located off -site of the development. When
it is required that the station serve a larger area than the proposed development, the
developer may enter into a pro-rata contract with the City to be reimbursed the cost of
excess capacity as other developments tie to the system; and
h.j. The on-site generator must have an unobstructed 36 -in. buffer on all sides and be
accessible by City service vehicles.
2. Wet Well/ Dry Well Arrangement
a. Orientation shall consider the routing of incoming sewers and force main;
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b. Orientation shall allow at least a 2-ton vehicle to directly access the wet well or the dry
well, forwards and backwards or larger vehicle as appropriate;
c. Wet wells and dry wells shall be separate structuresd by at least a water and gas tight
wall with separate entrances separated from each other by earth;
d. Wet wells shall have sloped bottoms to avoid excess sludge deposits;
e. The wet well shall have a lockable aluminum door with an aluminum frame and safety
grating. The minimum opening size shall be 4-ft. x 6-ft. with two (2) doors large enough
to adequately maintain the wet well. Door and frame shall be Bilco Type K, KD or an
approved equal;
f. The dry well or valve vault shall have a lockable aluminum door with an aluminum frame
and safety grating. The minimum opening size shall be 2-ft. x 3-ft. or large enough to
adequately maintain the dry well or meter vault. Door and frame shall be Bilco Type K,
KD or an approved equal;
g. The wet wells, dry wells, manholes, valve vaults and meter vaults, including decks, shall
all be cast-in-place concrete only. No other materials are acceptable. See City Standard
Specification 33 05 64 Concrete Wet wells, Valve Vaults, and Appurtenances for Lift
Stations;
h. The coating for the wet well exterior and interior walls shall be coated as specified in
Specification 33 05 64 Concrete Wet wells, Valve Vaults, and Appurtenances for Lift
Stations;Table 6.3-E and 6.3-F below, respectively;
i. The wet well shall be hydrostatically tested to the top of the wet well for 48 hours prior
to placing the lift station into service. Only losses due to evaporation will be acceptable;
and
j. Provisions shall be made to remove water from the dry well, valve vault or meter vault
without allowing gas or water from the wet well into these structures.
3. Exterior Walls (below grade, to be backfilled)
Table 6.3-E: Exterior Wall Coating
Surface Preparation Coating System
Clean and Dry Tnemec Series 46H-413 Polyamide Epoxy – Coal Tar
8 – 10 mils in two coats for a total of 13.0 to 20.0 dry mils
4. Interior Walls (Thick Film System)
Table 6.3-F: Interior Wall Coating
Surface Preparation Coating System
PRIMER FINISH
Brush-off Blast Cleaning Tnemec Series 218 Mortarclad ¼-in. Tnemec Series 436 Perma-Shield
100 – 125 dry mils
Notes:
[1] In addition to this coating system, the lining products listed in Drawing S101 of the City of Denton Standard Details
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Table 6.3-F: Interior Wall Coating
and Standard Specification 33 01 40 Liners for Sanitary Sewer Structures are acceptable.
5.3. Site Access
a. Access will be provided by concrete entrance and pad for aesthetics and ease of
maintenance. an all-weather surface of flex-base or better from a public street to the
station site;
b. Access shall be functional during a 100-year flood. The road surface shall be above the
water level caused by a 100-year return period storm;
c. Every station more than 100 feet from a public street requires a turn -around adjacent
to the lift station, sized large enough to accommodate a City service truck with
generator;
d. The equipment rack shall not obstruct vehicle access to the wet well or the dry well; the
location must be approved during the review process. It shall be placed at an easily
accessible elevation and include a canopy; and
e. Site inside the fence shall be an all-weather surface, such as ¾-in. crushed rock or flex-
base.
6.4. Passive Ventilation
a. Passive ventilation shall be screened to prevent insect access to the wet well or any
vaults where ventilation is required. Minimum diameter of air vents shall be four (4)
inches. Vent outlet shall be at least one (1) foot above the 100-year flood elevation. The
passive ventilation system must be sized to vent at a rate equal to the maximum
pumping rate of a lift station, but not to exceed 600 fpm through a vent pipe.
C. Hydraulic Design
For influent flow, the preliminary design report shall include the design flow and the peak flow for
the development and the sewer basin. The design flow shall be calculated in accordance with TCEQ
rules. Refer to Section 6.3.1 - Estimated Wastewater Flows herein for peak flow calculations.
1. Pump Capacity
a. Firm pumping capacity is the pumping capacity of the station with the largest pump out
of service.
b. The firm pumping capacity shall be greater than the peak flow for the entire sewer basin.
If the sewer basin is significantly larger than the proposed development and it is not
feasible to design for this flow, the firm pumping capacity may be designed to handle
a portion of the basin with approval from the City’s Engineer.
c. The pump curves shall be selected so the pumps will run near the best efficiency point
during normal operating conditions. The selected curves shall also be such that the
pumps do not approach shut-off head when they are running simultaneously.
d. System head curves, pump curves and head calculations shall be submitted.
Calculations and pump curves at both minimum (all pumps off) and maximum (last
normal operating pump on) static heads, for a C value of both 100 and 140, must be
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provided for each pump and for the combination of pumps with modified pump curves.
2. Wet Well Volume
a. Wet well volume for a submersible pump station is the volume contained above the top
of the motor, or as specified by the pump manufacturer, to the bottom of the influent
pipe. TCEQ Rule §217.60(b)(4) (d) A gravity pipe discharging to a wet well must be
located so that the invert elevation is above the liquid level of a pump's "ON" setting.
b. Wet well volume for all other non-submersible pump stations is the volume contained
in an area from a minimum of two (2) feet above or distance at which vortexing does
not occur above the top of the intake of the pump.
c. High level alarm elevation shall be a minimum of 48 inches below the top of the wet
well or 48 inches below the flow line elevation of the lowest influent pipe, whichever
elevation is lower. Wet well volume shall be calculated by the following method:
T = V/(D – Q) + V/Q [Eqn. 6.4]
Where: T = Total time between successive pump starts in minutes (operating cycle)
D = Rated pump capacity (in GPM)
V = Storage volume between lead pump on and pump off elevations (in
gallons)
Q = Inflow to wet well (in GPM)
Note: The operation cycle ‘T’ shall not be less than 10 minutes for Average Flow and not
more than 60 minutes for Minimum Flow conditions.
d. Per TCEQ Rules, 30 TAC § 217.63:
i. Systems for preventing the discharge of wastewater must operate for a duration at
least equal to the longest power outage on record for the past 60 months, or at
least 20 minutes, whichever is longer. The design must be based on peak flows,
inflow, and infiltration. If the longest power outage on record for the past 60
consecutive months is greater than 48 hours and generators will be used to provide
backup power, then the owner must have a contract in place that guarantees fuel
supply during an emergency. The owner must also have sufficient storage capacity
at the wastewater treatment facility for the fuel required for the duration of the
emergency.
ii. For calculation purposes, the owner must assume that the lift station wet well is
full to the pump activation level when the power outage period begins.
3. Force Main Capacity
a. Force main capacity shall be sized to meet the capacity of the entire sewer basin. The
force main may be designed to handle a portion of the basin with approval from the
City’s Engineer.
b. The minimum force main size shall be four (4) inches in diameter, except for Grinder
Pump lift stations.
c. The minimum recommended velocity is three (3) fps, and the velocity shall not be less
than two (2) fps when only the smallest pump is in operation.
d. The maximum velocity through a force main shall not be more than six (6) fps and will
require confirmation per 30 TAC §217.67 that the pipeline will not fail.
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D. Pumps
Pump specifications are listed in the City of Denton Specification 33 25 02 Sewage Pumps.
Substitutions or deviations from the list of acceptable pumps requires the approval of the City’s
Engineer. The number of pumps must comply with 30 TAC § 217.61(e). If pumps are to have a
variable capacity, Variable Frequency Drives (VFDs) are to be specified. Stations requiring three
pumps must be equipped with VFDs on at least two of the pumps.
E. Mechanical
1. Force Mains
a. Force mains shall be laid to City of Denton Standard Specifications.
b. Plans shall include plan and profile for the force main, including valves every 2 ,000 feet
per 30 TAC § 217.67.
i. Valves must be resilient wedge gate valves and conform to the Section 33 14 20
Resilient Seated (Wedge) Gate Valves of the City of Denton Standard
Specifications;
ii. Valves must be in a manhole and conform to Section 6.3.10 of this criteria manual
and Section 33 05 61 Cast-In-Place Concrete Manholes of the City Standard
Specifications; and
iii. The force main shall have an isolation valve immediately downstream of the flow
meter vault.
2. Lift Station Interior Piping
a. Piping inside the lift station shall be ductile iron meeting AWWA C-150 and C-151. All
fittings shall be ductile iron meeting AWWA C-110 or C-150. Interior of the pipe and
fittings shall be lined with American Polybond Plus, which consists of a primer layer of
5 mils thick fusion bonded epoxy and 55 mils thick of modified DuPont Fusabond
Polyethylene, or approved equal.
b. All nut and bolt assemblies potentially exposed to sewer gases inside the wet well shall
be ASTM 316 stainless steel.
3. Isolation Valves
a. Each pump shall have one (1) isolation valve downstream of the pump, in a separate
vault.
b. Isolation valves shall be resilient seat gate valves or plug valves meeting the City of
Denton Standard Construction Specifications.
4. Check Valves
a. Check valves shall be controlled closing swing check valves with a lever arm or a ball
check. There must be at least 15 feet of vertical head downstream in order to use a ball
check valve.
b. A check valve shall be located upstream of the isolation valve in a separate vault.
c. All nuts and bolts shall be stainless steel.
5. Air Release / Vacuum Valves
a. Air release valves of a type suitable for wastewater service shall be installed along the
force main where the force main would be prone to trapped air.
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b. The type of valve shall be air release or a combination of air release and vacuum breaker
(Ssee Drawing S803 on Sheet 6 of the City Standard Details). The design engineer shall
determine the type and location, subject to approval of the City’s Engineer.
c. Calculations for valve type and valve sizing shall be provided to the City.
d. Locations of the air release/vacuum valves shall be shown on the plan and profile sheets
for the force main.
e. Isolation valves for air release valves that are three (3) inches or smaller shall be all
bronze or brass. Isolation valves four (4) inches or larger shall meet City of Denton
Standard Construction Specification for resilient seat gate valve. The first fitting placed
into the force main shall be a brass corporate valve (male corporate fitting).
f. Air release valves shall be fitted with blow off valves, quick disconnect coupling and
hose to permit back flushing after installation without dismantling the valve.
e. Air release valves along the force main outside of the lift station site must be located in
a vault as shown in Standard Details.
g.f. Air release valves within the lift station valve vault shall have air vents plumbed to the
vault drain.
6. Generators
a. On-site generators shall be installed to serve as the source of back-up power for lift
stations. They must be sized for 125% of the largest pump motor, plus 100% of the
additional pump motors and other loads.
b. Generators shall be mounted on a concrete foundation designed to handle the weight
of the generator.
c. Generators shall be use diesel for fuel unless explicit written permission is granted to
use an a different fuel.
d. Electrical receptacles for a mobile load bank shall be provided in the electrical design.
e. Generators rated for 3500KWw or more shall be provided with a permanent load bank
situated to adequate dissipate the heat generated on the lift station site.
f. Generators shall be furnished with sound attenuation appropriate for the location.
7. Hoists
Station designs that exceed or are likely to exceed the lifting capabilities of the existing City
Water Reclamation service trucks are to provide permanent onsite hoists rated for the lifting
of the heaviest assembly in the wet well, considering rag accumulation.
F. Electrical, Instrumentation, and Supervisory Control and Data Acquisition (SCADA)
Requirements
1. In accordance with the Lift Station Instrumentation and Control Panel Build Agreement, the
contractor building the lift station is required to utilize a pre-approved vendor from the City's
current list to perform the specified Instrumentation and Controls (I&C) and SCADA work.
The selection of the vendor for a specific project will be made during the pre-construction
phase and will be based on vendor availability and project requirementsThe City of Denton
Water Reclamation Department performs the build and install of SCADA and telemetry
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packages. Developers should request the packet and the City of Denton will provide a bill
of materials for this service..
2. Provide a radio pathway study showing line of sight from the lift station to the receiver at
Pecan Creek Water Reclamation Plant.
3. Sites equipped with Variable Frequency Drives (VFDs) shall provide a climate-controlled
building for housing all electrical and electronic equipment.
7.4. Adequate lighting of the lift station wet well, valve vault, pump control equipment, electrical
and instrumentation equipment shall be included with the station design. All lighting
provided should be LED lighting.
6.3.176.3.18 Low-Pressure or Alternative Collection Systems
Low pressure collection systems may be allowed with specific approval by the City’s Engineer.
6.3.19 Wastewater Treatment Plants, And Peak Flow Detention Facilities
If wastewater treatment plants or peak flow detention facilities are needed to support a development, the
design shall be directed by the Water Utility considering the needs of the development and the Wastewater
Utility System.
6.3.186.3.20 On-Site Sewage Facilities
A. General
Planning, design and operation of on-site sewage facilities within the City of Denton must comply
with the current 30 TAC Ch. 285 for On-Site Sewage Facilities, as amended. The property owner
proposing to use an on-site sewage facility shall comply with the criteria listed in this Section, and
Section 7.6.16 of the City of Denton DDC, as amended.
B. Permits Required
Any owner of a residential, commercial, or institutional building who utilizes an on-site sewage
facility is required to secure a permit from the City of Denton to construct, alter, repair, or extend
an on-site sewage facility regardless of the size of the lot or tract of land. Contact the Environmental
Services Departmentivision at the Pecan Creek Water Reclamation Plant for details on permit fees
and maintenance requirements.
C. Site Evaluations
A Professional Engineer or a professional sanitarian, licensed by the State of Texas, must perform
site evaluations.
D. Planning Requirements
A Professional Engineer or a professional sanitarian, licensed by the State of Texas, must prepare
on-site sewage facility plans.
E. On-Site Sewage Facility Land Use Requirements
Lots or tracts of land where an on-site sewage facility is proposed must have the following minimum
area size.
1. A minimum of one (1) acre when a public water system serves the tract or lot; and
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2. A minimum of two (2) acres when a private water well is located on the tract or lot.
6.3.196.3.21 Pretreatment Device: Grease TrapsInterceptors / Grit Traps / Oil
Separators
A. General
Planning, design, and operation of grease traps pretreatment devices within the City of Denton
must comply with the most current City of Denton Plumbing Code, Chapter 28; Article VII; Section
286-56, as amended. The property owner proposing to use and operate a grease trap shall comply
with the criteria listed in this Section and abide by required responsibilities outlined in City of
Denton Code of Ordinances Chapter 26; Article XII – Liquid Waste.
Definitions can be found in the City of Denton Code of Ordinance, Chapter 26, Article XII, Section
26-306 and Chapter 26, Article V, Section 26-154.
B. Device RequiredApplicability
Any user of the publicly owned treatment works (POTW), as defined by Section 26-1543, and
meeting the definition of “food service facilities” or “facilities which perform washing, cleaning, or
servicing of automobiles, trucks, buses or similar equipmentgenerator,” as defined by Section 26-
306, shall be required to install a grease trap interceptor or grit trappretreatment device in
accordance with locally adopted plumbing codes as amended. Food service establishments shall
not share grease interceptors unless specifically authorized by the City’s Engineer.
These requirements are applicable to all commercial food service establishments, including those
that are undergoing:
1. New construction
2. Interior remodeling to accommodate expansion or operational modifications
3. Changes of ownership/occupancy
4. Facilities which fail to meet limitations outlined in article V, Chapter 26 of the Code of the
City of Denton, Texas
5. DWhen discharges which may cause blockages in the wastewater collection system
Unless otherwise approved in writing by the City, all fixtures, equipment, and drain lines located in
the food preparation, alcohol service, clean-up, and food service areas of a food service
establishment shall be connected to a grease interceptor. Fixtures required to connect to a grease
Interceptor shall include but are not limited to pot sinks, pre‐rinse sinks, hand sinks, prep sinks,
dishwashers, soup kettles, braising pans, wok ranges, mop sinks, floor sinks, floor drains, and
wastewater generated from exhaust fan hood cleaning operations.
C. Sample Port RequiredGrease Interceptor Requirements
Any pretreatment device must have a sample port allowing for the instantaneous grab sampling of
the effluent of the device. The sample port must be solely representative of the process wastewater
and sanitary tie-ins must be done down-stream of the sampling port. The proposed sampling port
must allow for a wide-mouthed 250-mL amber glass bottle to be submerged / partially submerged
into the effluent.
Unless otherwise approved in writing by the City, all fixtures, equipment, and drain lines located in
the food preparation, alcohol service, clean-up, and food service areas of a food service
establishment shall be connected to a grease interceptor. Fixtures required to connect to a grease
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design GuidelinesCriteria
6.3.21 Pretreatment Device: Grease TrapsInterceptors / Grit Traps / Oil Separators
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Interceptor shall include but are not limited to pot sinks, pre‐rinse sinks, hand sinks, prep sinks,
dishwashers, soup kettles, braising pans, wok ranges, mop sinks, floor sinks, floor drains, and
wastewater generated from exhaust fan hood cleaning operations.
D.C. Review Required
Plumbing plans for new facilities must be prepared by a plumber or a Professional Engineer,
licensed by the State of Texas, and submitted as a part of the development process. These plans
must show the fixtures draining into the pretreatment device. Plans must also include the flow-
through rating of the pretreatment device as well as the grease or solids retention capacity. Plans
must also show and, the location of the down-stream sampling port. Plumbing plans for existing
facilities must be submitted when applying for a certificate of occupancy. These plans must show
the fixtures draining into the pretreatment device and indicate the flow through rating and grease
and solids capacity of the pretreatment device.
D. Construction/Installation
All permitting, construction, and inspection activities must be completed in accordance with the
City of Denton Plumbing Code Chapter 28. Additionally, the following specifications must be
incorporated into grease trappretreatment device design.
1. The grease interceptor shall be constructed with a minimum of two baffles. Each manhole
access shall behave minimum 20-in.” diameter clear opening.
2. Grease trapsPretreatment devices are to be installed at a minimum distance of 10 fteet. from
sinks and dishwashers to allow for adequate cooling of the wastewater. Water temperatures
must be less than 120 degrees prior to entering grease trapthe pretreatment device.
3. Pretreatment devices shall be constructed of a material that is compatible with the type of
waste generated by the Facility and treated by the device.
3. All grease bearing waste streams should be routed through an appropriate grease
trap/interceptor, including: three-compartment sinks, pot/pan sinks, soup kettles, hand-
washing sinks, automatic dishwashers, mop sinks and floor drains.
4.
5. Any pretreatment device must have a sample port allowing for the instantaneous grab
sampling of the effluent of the device. The sample port must be solely representative of the
process wastewater and sanitary tie-ins must be done down-stream of the sampling port.
The proposed sampling port must allow for a wide-mouthed 250-mL amber glass bottle to
be submerged or partially submerged into the effluent. Interior, above-ground
hydromechanical grease interceptors with a liquid capacity of 100 gallons or less may install
a sample spigot with a ball valve in leu of a sample port due to space constraints with Ccity
approval. The sample spigot must be solely representative of the process wastewater and
sanitary tie-ins must be done down-stream of the sample spigot. Sample wells will have a
minimum 12”-in. diameter access cover. Mechanical Traps and Interceptors that are installed
above ground must be equipped with an influent flow regulator and an effluent valve
assembly that allows for sample collection.
Unless otherwise approved in writing by the City’s Engineer, all fixtures, equipment, and drain lines
located in the food preparation, alcohol service, clean-up, and food service areas of a food service
establishment shall be connected to a grease interceptor. Fixtures required to connect to a grease
Interceptor shall include but are not limited to pot sinks, pre‐rinse sinks, hand sinks, prep sinks,
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design GuidelinesCriteria
6.3.21 Pretreatment Device: Grease TrapsInterceptors / Grit Traps / Oil Separators
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dishwashers, soup kettles, braising pans, wok ranges, mop sinks, floor sinks, floor drains, and
wastewater generated from exhaust fan hood cleaning operations.
E. Grease Interceptor Sizing Requirements
Sizing methods described herein are intended as guidance in determining grease trap/interceptor
sizes that will afford the City’s sanitary sewer system a minimum degree of protection against grease
and other obstructing materials. Sizing determinations are based on operational data provided by
business owners or their contractors. In approving a customer’s plumbing or grease interceptor
design, the City does not accept liability for the failure of a system to adequately treat wastewater
to achieve effluent quality requirements specified under City of Denton Code of Ordinance Chapter
26. It is the responsibility of the wastewater generator and/or contractors to insure the appropriate
level of treatment necessary for compliance with environmental and wastewater regulations.
1. DefinitionsGravity Grease Interceptors (GGI) shall meet the requirements of ASME A112.14.6
and IAPMO/ANSI Z1001. The required capacity of gravity grease interceptors shall be
determined by multiplying the peak drain flow into the interceptor in GPM by a retention
time of 30 minutes as required by the International Plumbing Code.
a. Heavy Food Preparation: Any area in which foods are prepared utilizing a grill, griddle,
deep-fat fryer, commercial type ovens, and/or any similar food preparation equipment;
or any area subject to flooding type of wet cleaning procedures due to the cutting or
processing of meat, poultry, fish or pork; or any facility subject to rinsing preparation
equipment that is exposed to dairy products. Heavy food preparation includes, but is
not limited to, cafeterias, coffee shops, fast food restaurants, full service restaurants;
pizza preparation, donut preparation, and meat and fish markets, etc.
b. Light Food Preparation: Any area in which foods are prepared exclusive of the use of
fryers, grills or similar equipment. Light food preparation is usually limited to the
preparation of hot dogs, sandwiches, salads or other similar foods and fountain-type
cold drinks. Light food preparation includes, but is not limited to, sandwich shops,
limited-menu concession stands, etc.
c. No Food Preparation: Any area in which foods are provided pre-wrapped, from an
approved source, with microwave oven type heating being the maximum handling
involved. No food preparation is limited to pre-packaged sandwiches or similar foods,
candies and containerized beverages.
2. Grease Trap Design CriteriaHydromechanical Grease Interceptors (HGI) shall be designed and
tested in accordance with ASME A112.14.3 and/or CSA B481.1. Sizing shall be in accordance
with HGI Sizing and Selection, as shown in the following two-step process:
a. Step 1: Size by Flow Rate
The minimum flow rate for HGIs may be calculated by either using pipe diameter or
fixture volume using either a one-minute or two-minute drainage period. Use a one-
minute drainage period when the interceptor will be installed inside of the building and
has indirectly connected fixtures. When the interceptor will be installed outside of the
building, use a two-minute drainage period.
i. Fixture Volume Sizing
Use the following formula for sizing fixtures by volume with a 75% fill factor:
Fixture Capacity Gallons = [ (L x W x H ) / 231 ] x 0.75 [Eqn. 6.5]
Note that,
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design GuidelinesCriteria
6.3.21 Pretreatment Device: Grease TrapsInterceptors / Grit Traps / Oil Separators
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Fixture Capacity Gallons x 1 = one-minute drainage period (GPM)
Fixture Capacity Gallons x 0.5 = two-minute drainage period (GPM)
Example calculations are shown below for a three-compartment sink with each
compartment dimensions being 18 x 24 x 12 inches:
18 x 24 x 12 = 5184 cubic inches (in3)cu. in.
5184 / 231 = 22.44 fixture capacity gallons
22.44 x 3 = 67.3 total fixture capacity gallons (three bowls)
67.3 x 0.75 = 50.4 total fixture capacity after loading factor (75%)
50.4 x 1 = 50 GPM one-minute drainage period
50.4 x 0.5 = 25 GPM two-minute drainage period
To determine the minimum required flow rate for the HGI, calculate the capacity
of each fixture that will be connected and add the volumes together and use the
appropriate drainage period. An appropriate HGI must be certified to meet the
minimum flow rate as calculated.
b. Step 2: Calculate Grease Capacity
Once the minimum flow rate has been established as detailed in Step 1, the minimum
grease storage capacity for the HGI required for the desired pump-out frequency is
calculated as follows:
Grease Capacity Needed = Meals per day x GPV x DPC [Eqn. 6.6]
Where: GPV = Grease Production Values (See FSE Values in Table 6.3E below)
DPC = Days per Pumpout Cycle [Recommended 90 days]
Table 6.3-E: Typical Grease Productions Values for Ttypical FSEs
Menu w/o Fryer,
No Flatware
w/o Fryer,
Flatware
w/ Fryer,
No Flatware
w/ Fryer,
Flatware
Bakery 0.035 0.0455 0.035 0.0455
Bar - Drinks Only 0.005 0.0065 0.025 0.0325
Bar and Grille 0.035 0.0455 0.035 0.0455
BBQ 0.035 0.0455 0.035 0.0455
Buffet 0.035 0.0455 0.035 0.0455
Burger Joint 0.025 0.0325 0.035 0.0455
Cafeteria - Full Serve 0.035 0.0455 0.035 0.0455
Cafeteria - Heat & Serve 0.025 0.0325 0.035 0.0455
Chinese 0.035 0.0455 0.035 0.0455
Coffee Shop 0.005 0.0065 0.025 0.0325
Continental breakfast 0.005 0.0065 0.025 0.0325
Convenience Store 0.005 0.0065 0.025 0.0325
Deli 0.005 0.0065 0.025 0.0325
Donut Shop 0.005 0.0065 0.035 0.0455
Don't know yet 0.035 0.0455 0.035 0.0455
Family Restaurant 0.035 0.0455 0.035 0.0455
Fast Food - Limited Prep 0.025 0.0325 0.025 0.0325
Fast Food - Full Prep 0.035 0.0455 0.035 0.0455
Fried Chicken 0.035 0.0455 0.035 0.0455
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design GuidelinesCriteria
6.3.21 Pretreatment Device: Grease TrapsInterceptors / Grit Traps / Oil Separators
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Table 6.3-E: Typical Grease Productions Values for Ttypical FSEs
Greek 0.035 0.0455 0.035 0.0455
Grocery Store 0.035 0.0455 0.035 0.0455
Ice Cream/Yogurt/Smoothies 0.005 0.0065 0.025 0.0325
Indian 0.035 0.0455 0.035 0.0455
Italian 0.035 0.0455 0.035 0.0455
Mexican 0.035 0.0455 0.035 0.0455
Pizza Restaurant 0.025 0.0325 0.035 0.0455
Pizza Carryout 0.005 0.0065 0.025 0.0325
Multi-unit dwelling 0.005 0.0065 0.025 0.0325
Salads / Healthy Bowls 0.025 0.0325 0.025 0.0325
Sandwich Shop 0.005 0.0065 0.025 0.0325
Seafood 0.035 0.0455 0.035 0.0455
Snack Bar 0.005 0.0065 0.025 0.0325
Steak House 0.035 0.0455 0.035 0.0455
Sushi 0.005 0.0065 0.025 0.0325
Notes:
[1] To determine the correct grease factor, select the menu type, then the correct column for whether there is a fryer and whethe r the
establishment uses disposable or washable plates, glasses, knives, forks, and spoons (flatware).
[2] FSEs that are not open every day, may calculate the number of days open in a 90-day period and use that to calculate the total
amount of grease capacity required and must submit calculation for review.
Source: Brown Grease Supply Study, 2011, Kennedy/Jenks Consultants.
Example calculations are shown below for a Fast Food – Full Prep, with fryer, with
disposable flatware, serving 300 meals per day:
Grease factor from Table 6.3E = 0.035 pounds per meal
Meals per day = 300
Days between pump-outs = 90
Grease Capacity Needed = 0.035 x 300 x 90 = 945 pounds
The correctly sized and selected grease interceptor will have the minimum flow rate determined in
Step 1 and the grease storage capacity calculated in Step 2. Grease interceptors certified to meet
the minimum requirements of ASME A112.14.3 or CSA B481.1 shall have the flow rates and
minimum grease storage capacities as listed in Table 6.3-F below:
Table 6.3-F: Minimum Grease Storage Capacity for
Grease Interceptors
HGI Flow Rate
(GPM?)
Minimum Grease Storage Capacity[1]
(lbs.)
20 40
25 50
35 70
50 100
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design GuidelinesCriteria
6.3.22 Inspections Required
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Table 6.3-F: Minimum Grease Storage Capacity for
Grease Interceptors
75 150
100 200
Notes:
[1] Minimum grease capacity as required by ASME A112.14.3, PDI G101 and CSA B481.
Grease interceptors claiming grease capacities exceeding the minimum requirements in Table 6.3-
F, shall be reviewed and approved by the City when the manufacturer can demonstrate by third-
party test reports, including the incremental test data, that the interceptor(s) has the capacity
claimed. Upon approval from the City, the grease interceptors proven grease storage capacity may
be used in selecting the sizes and required number of units to satisfy the requirements of the two-
step sizing method in Section 6.3.21.E.2 of this Manual.
F. Laundries
Commercial lLaundries, laundromats, and dry cleaners shall be equipped with an interceptor to
reduce the quantity of lint and silt that enter the collection system. The system must be of adequate
size and design to allow for cool-down of wastewater so that separation can be more readily
achieved. The interceptor must be installed with a wire basket or similar device, removable for
cleaning, that prevents passage into the drainage system of solids ½- inch (12.7 mm) or larger in
size, string, rags, buttons, or other materials detrimental to the public sewerage system.
G. Car Washes
Where automobiles are washed (including detail shops utilizing hand-wash practices), separators
shall have a minimum capacity of 1000 gallons for the first bay, with an additional 500 gallons of
capacity for every other bay.
H. Automotive Repair Facilities (Garages and Service Stations)
Where automobiles are serviced, greased, or repaired or where gasoline is dispensed, oil or water
separators shall have a minimum capacity of 500 gallons for the first 1000 sq. ft. of area to be
drained, plus 250 gallons for each additional 1000 sq. ft. of area to be drained into the separator.
Table 6.3-G: Grease Trap Design Criteria1
Classification Seating Capacity2 > 50 Seating Capacity2 < 50
Heavy Food Preparation 750-gal. gravity grease interceptor 250-gal. grease interceptor
Light Food Preparation 250-gal. gravity grease interceptor 20 GPM flow-through rating or
40-lb. retention capacity
No Food Preparation No interceptor required
Notes:
[1] Or the minimum size established by the currently adopted International Plumbing Code; whichever is more stringent.
[2] Seating Capacity is measured using locally adopted Maximum Floor Area Allowances per Occupant, found in the
currently adopted version of the International Building Code.
6.3.206.3.22 Inspections Required
New installations or existing pretreatment devices must be inspected by the City of Denton Pretreatment
Section 6: Water and Wastewater Design Criteria
6.4 Construction Plans
6.4.4 General
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Program prior to the issuance of a Certificate of Occupancy for new businesses.
6.4 Construction Plans
6.4.1 General
Before any public works construction relative to a development may begin, City staff will verify the
construction plans have been approved. Construction may not begin until the construction plans have been
approved, all materials used for public improvements have been submitted and approved, all fees (including
review and inspection fees) have been paid, all necessary agreements and bonds have been provided, and
a Pre-Construction Conference has been held by the City.
6.4.2 Responsibility
The sealing engineer is responsible for the accuracy, completeness, and conformance of the submitted plans
to City standards. The purpose of the City review is to ensure conformance to City policies and standards.
The City review is limited to facts as presented on the plans submitted. The City has no project engineering
design or quality control review responsibility. The engineer of record certifying the plans is responsible for
the accuracy and completeness of the plan documents. The City reserves the ri ght to require plan
corrections to fit actual field conditions or meet City standards requirements, which are found to be contrary
to or omitted from the plans.
6.4.3 Format
Construction plans shall be digitally drawn on 24-in. x 36-in. size sheets with borders of 22-in. x 34-in., so
half-size reproduced plans will be to half-scale fitting 11-in. x 17-in. sheets. Each sheet shall be legible when
reduced to half-size. Digital copies of the plans shall also be provided.
6.4.4 Plan Requirements
Construction Plans must contain, as a minimum, information listed in the following sections before they can
be approved:
A. General
North arrow, scale, date, and mean sea level elevations of all improvements, based on North
America Vertical Datum 1988 (NAVD 88). Only NAVD 88 shall be used for plan elevations; no
assumed or NGVD 29 elevations. Plans shall be drawn with a horizontal scale of one (1) inch equals
40 feet as a minimum, and appropriate corresponding vertical scale. The plans shall provide a
reference to the elevation benchmark or monument used in the development of the plans. Show
all crossings of existing and proposed underground utilities. Plans shall account for future changes
in topography. The construction plans shall be signed and sealed by a Professional Engineer,
licensed by the State of Texas, prior to bidding the project for construction.
B. Water Systems
Plan sheets must show the horizontal alignment of the proposed water system within street ROWs
and easements, with horizontal control points for location of the ROWs and easements and for
location of the water system within the ROWs and easements. Sizing of pipe, valves, fittings and
appurtenances must be shown on the plan view. All valves, fittings, fire hydrants, and other
appurtenances must be stationed and given GPS coordinates (with an accuracy of ± six (6) inches)
Section 6: Water and Wastewater Design Criteria
6.4 Construction Plans
6.4.4 Plan Requirements
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based on the City of Denton’s grid coordinate system. Profile views of water mains 12 inches or
larger must shall be provided showing proposed grade, pipe material, casing pipe size and thickness
(if any), and the location, elevation and size of any underground conduit or facility to be crossed.
Deflections (if any) must be shown on the plan and profile views, as applicable, with stationing and
the degree of deflection. Approved design deviations (if any) from City Standard Details must be
provided. Show all service lines up to and including the meter can/vault. Service lines do not need
to be stationed or have GPS coordinates. Adequate detail of other planned and existing
improvements shall be shown to indicate planned crossings of utilities, storm drains, and
stormwater facilities and potential conflict points.
C. Sanitary Sewer Systems
Plan sheets must show the horizontal alignment of the proposed sanitary sewer system within street
ROWs and easements, with horizontal control points for location of the ROWs and easements and
for location of the sanitary sewer system within the ROWs and easements. Sizing of pipe, manholes,
fittings and appurtenances must be shown on the plan view. Manhole rim elevations, and pipe “IN”
and “OUT” elevations must be shown. All manholes, fittings, and other appurtenances must be
stationed and given GPS coordinates (with an accuracy of ± six (6) inches). based on the City of
Denton’s grid coordinate system. Every sanitary sewer line shall be profiled. Profile views shall show
proposed grade, pipe material, casing pipe size and thickness (if any), manhole information, and
the location, elevation and size of any underground conduit or facility to be crossed. Approved
design deviations (if any) from City Standard Details must be provided. The plan view shall include
arrows indicating direction of flow in pipe. Show all service lines to and including the public
cleanout. Service lines do not need to be stationed or have GPS coordinates. Adequate detail of
other planned and existing improvements shall be shown to indicate planned crossings of utilities,
storm drains, and stormwater facilities and potential conflict points.
D. Grading
For situations involving proposed grading over existing water or sanitary sewer systems, provide a
grading plan and profile showing the existing and proposed topography in 2-ft. contours. The
grading plan shall consist of contours and spot elevations with water directional arrows to define
the flow patterns.
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Section 7: Streetlight Design Criteria
7.1 Overview
The purpose of Section 7 – Streetlight Design Criteria is to assist developers and engineers in creating an
aesthetic, consistent, and safe lighting plan for our streets, sidewalks, and neighborhoods. This section
outlines the process for design, review, and approval of new lighting projects, as well as criteria for
modernizing existing lighting infrastructure. Streetlights are usually owned by Denton Municipal Electric
(DME) which is a part of the City of Denton (the City), however they may be installed, operated, and
maintained by DME, other electric utilities, or private owners depending on the location. This section of the
DCM has been created to help navigate the process for selecting, permitting, placing, and maintaining
streetlighting throughout the city. This manual does not apply to security, area, pathway, private, or other
lighting not associated with a public road.
This manual cannot cover all the situations that might be encountered, required, or requested in the
construction and installation of streetlighting. Any apparent discrepancy, omission, error, or requirement
necessitating further explanation or interpretation should be referred to DME Engineering (940-349-7117
or 940-349-4173) for further clarification.
The goal of the criteria laid out in this Section 7 is to implement the following guiding principles into the
application of street designs in the City of Denton:
A. Enhance safety of the community for pedestrians and drivers alike
B. Conserve energy by prioritizing efficient lighting design
C. Minimize impact to the environment including light pollution
D. Minimize impact to neighborhoods and residences by reducing light trespass
E. Provide for a uniform and aesthetic look throughout the city
F. Be fiscally responsible through effective application of design principles
7.1.1 Applicability
The existing streetlight installations throughout the City of Denton have been accepted as is at the time of
approval of this manual. Retro-active replacements and upgrades solely for the purpose of bringing existing
lighting up to the standards of this manual are not required. This manual is intended to apply to all new
projects in the City beginning July 1, 2024. (This means the project has been approved/permitted by
Development Services on or after July 1, 2024).
7.1.2 Organization
Section 7 – Streetlight Design Criteria is organized as follows:
A. Overview
B. Requirements
C. Developer & DME Responsibilities
Section 7: Streetlight Design Criteria
7.2 Requirements
7.2.2 General
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7.2 Requirements
7.2.1 General
The City adheres to the guidance of ANSI RP-8 Recommended Practice for Design and Maintenance of
Roadway and Parking Facility Lighting for all highways and streets except for local residential streets with
speed limits of 30 mph or less. ANSI RP-8 acknowledges that vehicle headlights may provide adequate
illumination for slower speeds when the driver has sufficient time for reaction and stopping. As per ANSI
RP-8, Section 11.6.3.1 – ‘When Residential Street Lighting May Not be Needed’, for local residential streets
(e.g., within a residential development) with speed limits of 30 mph or less, street lighting shall be placed
no more than 250 feet apart. A photometric (lighting) study will be required for all new installations except
for local residential streets with speed limits of 30 mph or less.
These standards shall apply to all new streetlight installations, upgrades, replacements, and conversions
from the date of the adoption of these standards onward.
Easement, ROWright-of-way, and permitting regulations that are not listed in this manual still apply to
streetlights. The developer is responsible for knowing and adhering to any laws and regulations governing
development and construction relating to the work being done.
Developers are responsible for the design, materials, and installation costs of all streetlighting on public
streets within and adjacent to their project. See the Developer and DME Responsibilities Section of this
manual for more specific descriptions of responsibilities. DME will only energize new streetlights after the
installation has been approved by DME. For most lighting installations, following energization, DME will
accept ownership and maintenance of streetlights unless the lighting is located o n a private drive (i.e. the
City has not taken ownership of the street / streetlights) or the lighting is non-standard and will not be
owned or maintained by DME.
Streetlights are not normally metered. The City (or customer in certain cases) is charged a monthly usage
and maintenance fee per light according to the Denton Municipal Utility Rates Manual. This does not apply
to private drives and other private properties where the developer or customer chooses to install lighting
other than the standard Ccity approved options. In such cases, DME will provide a metered service point
only and the customer will be responsible for all installation, maintenance, and fees associated with the
lighting installation in accordance with applicable Ccity codes, ordinances, and utility service standards for
the life of the installation.
City streets and street projects will not be considered complete until adequate streetlighting has been
installed, approved, and energized. For example, for the streets in a new development to be accepted by
and turned over to the City, street lighting must be complete.
7.2.2 Roadway Lighting Requirements
A. Roadway Designations
To determine the proper lighting for a roadway, it is important to determine what type of vehicle
and pedestrian traffic the roadway is meant to accommodate. Roadways may be classed into
several different categories based on these two variables. The lighting requirements are then
applied to provide adequate lighting to mitigate the risks of collision by a vehicle with another
object, vehicle, or pedestrian.
Roadways may be classified as highways and freeways, arterials, collectors, and local roads. In this
section of the DCM, local roads may also refer to auxiliary roadways such as alleys, drives, dead-
ends, and cul-de-sacs. Local roads may be residential streets (providing direct access to homes) or
other local roads providing access to businesses and connecting larger roads together. Local roads
Section 7: Streetlight Design Criteria
7.2 Requirements
7.2.2 Roadway Lighting Requirements
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generally have speed limits of 30 mph or less, while highways, arterials, and collectors will have
higher speed limits. Local roads are further broken down into residential and non-residential streets
in portions of this section to allow flexibility in managing light levels in residential neighborhoods.
Specific road classification and design information may be found in Section 5 – Transportation
Design Criteria of this DCM.
B. Lighting Evaluations and Design
For streetlighting of highways and streets, except local residential streets with speed limits of 30 mph
or less, lighting shall be designed per ANSI RP-8. A photometric (lighting) study will be required
for these new installations. ANSI RP-8 requires that a pedestrian activity classification be made to
determine the required lighting levels. See ANSI RP-8 for further guidance on pedestrian activity
classification and streetlighting design requirements. Additional information may also be found in
the TxDOT Highway Illumination Manual, and AASHTO GL-7, “Roadway Lighting Design Guide”. All
designs adhering to ANSI RP-8 standards shall be verified and documented using appropriate
lighting design software. A licensed Professional Engineer in the state of Texas shall stamp all
lighting designs before each submittal.
For all local residential streets with speed limits of 30 mph or less, street lighting shall be installed at
intersections, cul-de-sacs, and no more than 250 feet apart for the remainder of the street. Lighting
may be installed along one side of the street, both sides in parallel, both sides alternating, or in the
median. Separation distances should be measured along the centerline of the street. Additional
lighting may need to be considered if there are obstacles or road geometries that cutoff some of
the light. See the Sample Local Residential Streetlighting Layout shown below in Figure 7.1.
When designing or adding streetlights to existing roadways and/or neighborhoods, consideration
should be given to the style and placement of any existing fixtures. New streetlighting shall be
chosen from the available styles that most closely matches the style of the existing lighting in the
area. Historic poles are only approved for specific applications and areas designated as historic
districts or within the Downtown Implementation Plan area.
Section 7: Streetlight Design Criteria
7.2 Requirements
7.2.2 Roadway Lighting Requirements
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Figure 7.1 Sample Local Residential Street Lighting Layout
(Lights are shown at intersections, cul-de-sacs, and mid-block
when spacing between lights exceeds 250 feet)
C. Intersection and Crosswalks
Intersections have a much higher number of potential conflict points as vehicles and pedestrians
are permitted to cross through normal lanes of traffic. Therefore, additional care is needed when
planning intersection lighting. ANSI RP-8 should be used to design lighting at intersections for
larger, busier streets as stated previously. See Figure 7.2 shown below.
Because of the additional safety concerns for vehicles, cyclists, and pedestrians at crosswalks and
intersections, the following examples (taken from ANSI RP-8) are provided to assist streetlight
design for local streets. While not strictly required, they should be considered as good lighting
practice for these types of locations.
Section 7: Streetlight Design Criteria
7.2 Requirements
7.2.2 Roadway Lighting Requirements
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Figure 7.2 Typical Lighting Schematic for Intersections
D. Roundabouts and Traffic Circles
Like intersections, roundabouts and traffic circles have a higher number of potential conflict points
than normal streets. ANSI RP-8 should be used to design lighting at traffic circles and roundabouts
of larger streets. For local streets, an example of round-about lighting design considerations is
shown below. Some locations may not require as much lighting as shown depending on the size
of the traffic circle. See Figure 7.3 shown below.
Section 7: Streetlight Design Criteria
7.2 Requirements
7.2.2 Roadway Lighting Requirements
Design Criteria Manuals 198
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Figure 7.3 Roundabout Lighting Placement Schematic
E. Railroad Crossings
Railroad crossings are slightly different than normal intersections and require lighting adjustments
accordingly. It is of course, vitally important that drivers are able to see a train that is crossing, and
conversely, that the train engineer has a clear picture of any obstructions while approaching an
intersection. Street lighting at railroad crossings should therefore illuminate the intersection while
not causing glare for the drivers or train engineer. The following figure illustrates the recommended
lighting placement for a railroad crossing. See Figure 7.4 shown below.
Section 7: Streetlight Design Criteria
7.2 Requirements
7.2.3 Installation Requirements
Design Criteria Manuals 199
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Figure 7.4 Railroad Crossing Schematic
7.2.3 Installation Requirements
A. Placement
1. Highways and Streets (except for local residential streets with speed limits of 30 mph or less)
Installation should follow TxDOT recommendations in the TxDOT Highway Illumination
Manual. Where TxDOT requirements do not apply, the streetlight system shall be installed
in the ROWright-of-way or within public utility easements and poles should be placed
approximately 2.5 feet back from curbs and 10 feet back from edge of paving for uncurbed
roads or, where there is sidewalk abutting the curb, approximately 1 foot behind the
sidewalk. Deviations of more than 1 foot in either direction from these requirements must
be approved by DME Engineering.
2. Local Residential Streets (speed limits of 30 mph or less)
The streetlight system shall be installed in the ROWright-of-way or within public utility
easements. Poles should be placed approximately 2 feet back from the curb of 10 feet from
un-curbed pavement. If a sidewalk abuts the curb, then the pole should be placed
approximately 1 foot behind the sidewalk. In a residential neighborhood, streetlights should
be placed within 5 feet of common property lines (e.g. between neighbors).
B. Vertical and Horizontal Clearance
New streetlights should not interfere with existing structures or rights-of-way, including sidewalks,
nor should the placement preclude the ability to perform maintenance on the pole in a safe manner.
See National Electric Safety Code (NESC) Ssection 234 for specific clearances required for overhead
Section 7: Streetlight Design Criteria
7.2 Requirements
7.2.3 Installation Requirements
Design Criteria Manuals 200
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electric installations. The exception to this requirement is when streetlight arms are mounted
directly to wooden distribution poles.
Proposed trees should be located at least 25 feet from any streetlight location. When installing
new lights in a location with existing trees, consideration should be given to the age and maturity
of the tree and whether it will interfere with the light when it is fully grown. DME will be responsible
for tree trimming around streetlights to preserve the integrity of streetlighting as needed.
Median-mounted poles should be installed at least 20 feet back from an intersection to minimize
the number of vehicle-streetlight collisions due to vehicles and trucks turning too sharply at the
intersection.
In areas predominantly served by overhead electric powerlines, streetlights are usually installed by
attaching streetlight arms to existing wood distribution poles. Care should be given when planning
for lighting in these areas as overhead lines pose a conflict when placing new lighting poles.
Clearances must be maintained for safety. Redesign/relocation of existing overhead power lines
just to accommodate lighting is costly and time consuming. Utilizing existing wood pole locations
and installations on the opposite side of the street are two ideas for additional placement options
in these areas.
C. Approved Fixtures and Materials
The approved streetlight components for each class of roadway are listed below in Tables 7.2-A
and 7.2-B.
Section 7: Streetlight Design Criteria
7.2 Requirements
7.2.3 Installation Requirements
Design Criteria Manuals 201
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Table 7.2-A: Approved Luminaires and Hardware by Location
ROADWAY
CLASSIFICATION
ROADWAY CLASSIFICATION
HIGHWAYS AND
FREEWAYS
(UNLESS OTHERWISE
SPECIFIED BY TXDOT)
ARTERIALS AND LARGE
COLLECTORS ALTERNATE ARTERIALS
AND COLLECTORS
COLLECTORS AND
LOCAL STREETS
EXISTING
RESIDENTIAL
LOCAL STREETS
(ALSO USED IN
HISTORIC
DISTRICTS)
NEW
RESIDENTIAL
LOCAL STREETS
(≤ 30 MPH)
Make Signify Lumec RFL Signify Lumec RFM Gardco Optiform M Signify Lumec RFM Hadco Gardco
Model
RFL-241W112LED-
4K-G2-R2M-UNV-
DMG-ML-RCD7-
API-GY3
RFM-160W48LED-
4K-G2-R2M-UNV-
DMG-ML-RCD7-
API-GY3
OPF-M-A10-840-
2TM-MAR-UNV-
TR7-DGY
RFM-85W24LED-
3K-G2-R2M-UNV-
DMG-ML-RCD7-
API-GY3
C-1891P
RL34AANN2A
SNR7WA3
NNNNSP1
OPF-S-P05-
730-T2M-
AR1-UNV-
SP2-TR7
Wattage 241W LED 160W LED 112W LED 85W LED 69W LED 66W LED
Lumens 30,188 19,489 20,357 8,753 7,734 11,253
Color
Temperature 4000k 4000K 4000K 3000K 3000K 3000K
Light Distribution
Type Type II Type II Type II Type II N/A Light II
Voltage 120 – 277V or
347 – 480V
120 – 277V or
347 – 480V 120-277V 120 – 277V or
347 – 480V 120 - 277V 120 – 277V
B-U-G Rating B4-U0-G4 B3-U0-G3 B3-U0-G3 B3-U0-G3 B2-U5-G4 B2-U0-G2
Pole Type Steel, white
concrete, or wood
Steel, white
concrete, or wood Dark Gray Steel Steel, white
concrete, or wood
Residential -
Concrete
aggregate
Historic – Cast
Aluminum
Steel, square,
gray
Globe Type N/A N/A N/A N/A
Hadco, RL34
Acrylic
Victorian
N/A
Arm Type
8-ft. metal
(specs depend on
pole type)
8-ft. metal
(specs depend on
pole type)
8-foot metal
8-ft. metal
(specs depend on
pole type)
N/A Std-mount, no
arm
Section 7: Streetlight Design Criteria
7.2 Requirements
7.2.3 Installation Requirements
Design Criteria Manuals 202
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Table 7.2-B: Approved Pole Types by Location
Part Information Part Description
Highway
and
Freeway 1
Arterial
and
Large
Collector
Collector
and
Local
Street
Existing
Res.
Local
Street
Historic
District 2
New
Res.
Local
Street 3
POLE TYPE – WOOD DISTRIBUTION
N/A
Wood pole.
Various heights, but standard id 35 feet.
DME warehouse item.
Direct buried. Overhead electric service.
Yes Yes Yes Yes No No
Arm - Shakespeare
#OPAR-8-H
8-ft. curved aluminum arm.
DME warehouse item. - - - - - -
POLE TYPE – WHITE CONCRETE
Lonestar #351101 35-ft. Concrete pole, white color.
Single or double arm available.
DME warehouse item.
Direct buried. Underground electric service.
Yes Yes Yes Yes No No
Arm - Curlee
#2009032TG-Flat Base
8-ft. flat aluminum arm.
DME warehouse item. - - - - - -
POLE TYPE – CONCRETE AGGREGATE
Lonestar #20004-SJB
(Waterford Series)
20-ft. Concrete aggregate pole.
Post-top luminaire configuration.
Direct buried. Underground electric service.
Legacy – replacement and maintenance only
No No No Yes No No
POLE TYPE – ANTIQUE ALUMINUM
Acuity #PX-CP18-12-
F4-AB3/133T3-ANBK
12-ft. antique, decorative aluminum pole.
Post-top luminaire configuration.
Requires concrete foundation. Underground service.
No No Yes2 Yes2 Yes2 No
POLE TYPE – EMBEDDED STEEL
(Single Arm)
KW Industries
RTSU35-9.0-11-
RAL7043-18S-GS-E
35-foot round steel pole, gray color (RAL7043).
Single arm, direct buried pole. Underground electric service.
Arm included with pole.
Pairs with Gardco Optiform M luminaire.
Yes Yes Yes No No No
(Double Arm)
KW Industries
RTSU35-9.0-11-
RAL7043-28S-GS-E
For use in medians.
35-foot round steel pole, gray color (RAL7043).
Double arm, direct buried pole.
Underground electric service.
Arm included with pole.
Pairs with Gardco Optiform M luminaire.
Yes Yes No No No No
Section 7: Streetlight Design Criteria
7.2 Requirements
7.2.3 Installation Requirements
Design Criteria Manuals 203
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Part Information Part Description
Highway
and
Freeway 1
Arterial
and
Large
Collector
Collector
and
Local
Street
Existing
Res.
Local
Street
Historic
District 2
New
Res.
Local
Street 3
POLE TYPE – BREAK-AWAY STEEL4
(Single Arm)
KW Industries
RTSU35-9.0-11-
RAL7043-18S-GS-
BSC-1.00-SKT
Foundation 30” x 96”
Concrete
35-foot round steel pole, gray color (RAL7043).
Single arm, breakaway base mounted on a poured concrete
foundation.
Underground electric service.
Arm included with pole.
Pairs with Gardco Optiform M luminaire.
Contact DME for poured concrete foundation standards.
Yes4 Yes4 No No No No
Double Arm (Single
Arm)
KW Industries
RTSU35-9.0-11-
RAL7043-28S-GS-
BSC-1.00-SKT
Foundation 30” x 96”
Concrete
For use in medians. 35-foot round steel pole, gray color
(RAL7043). Double arm, breakaway base mounted on a poured
concrete foundation.
Underground electric service.
Arm included with pole.
Pairs with Gardco Optiform M luminaire.
Contact DME for poured concrete foundation standards.
Yes4 Yes4 No No No No
POLE TYPE – BRIDGE-MOUNT STEEL STEEL5
(Single Arm)
KW Industries
RTSU35-9.0-11-
RAL7043-28S-GS-
ATB1-17
Foundation TXDOT
Bridge
For use in medians. 35-foot round steel pole, gray color
(RAL7043). Double arm, breakaway base mounted on a concrete
bridge foundation.
Underground electric service.
Arm included with pole.
Pairs with Gardco Optiform M luminaire.
Yes Yes No No No No
POLE TYPE - STEEL
(Single Arm) KW
Industries RTSU35-8-
11-Gray-18S-N
35-ft. round steel pole, gray color.
Single or double arm available.
Used for TxDOT designed streetlighting.
Yes4 Yes4 No No No No (Double Arm) KW
Industries RTSU35-8-
11-Gray-28S-N
Part numbers may vary slightly depending on application.
Not stocked by DME – custom order item.
Breakaway bases with concrete foundations may be required for
certain installations and bridges.
Direct burial available also. Underground electric service
Arm(s) – N/A Arms are included with pole when ordering. - - - - - -
Breakaway base – N/A Breakaway base included with pole when ordering. - - - - - -
Section 7: Streetlight Design Criteria
7.2 Requirements
7.2.3 Installation Requirements
Design Criteria Manuals 204
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Part Information Part Description
Highway
and
Freeway 1
Arterial
and
Large
Collector
Collector
and
Local
Street
Existing
Res.
Local
Street
Historic
District 2
New
Res.
Local
Street 3
POLE TYPE – STEEL RESIDENTIAL
KW Ind., Part# SSP20-
4-11-DGY GARDCO-
DM10-BC
Foundation 24” x 72”
Concrete
20-ft., dark gray (RAL7043), 4-in. square steel pole.
Drilled for single-luminaire with std standard mounting pattern.
Underground service.
Pairs with Gardco Optiform S luminaire.
Contact DME for poured concrete foundation standards.Includes
3-in. by5-in. handhole and 8-in. bolt circle base pattern. Requires
concrete foundation. Underground service.
No No No No No Yes
Notes:
[1] Unless, otherwise specified by TxDOT.
[2] Historic streetlighting is only available for use in designated historic districts.
[3] Speed limits of 30 mph or less.
[4] Steel streetlight poles are only used for highways and roadways where TxDOT or City-approved plans require placement of break-away bases or non-standard mounting heights.
Section 7: Streetlight Design Criteria
7.2 Requirements
7.2.3 Installation Requirements
Design Criteria Manuals 205
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D. Historic Lighting
Historic lighting is a modern light fixture with a decorative pole and fixture that give the lighting
the look of early 20th century lighting. Historic lighting has been approved for use only in the
designated historic districts of Denton. All requests for historic lighting within these districts must
be submitted to DME Engineering for design and approval. Historic lighting is not approved for
installations outside of the historic districts. The requesting organization, developer, or agency shall
be responsible for all costs related to the design and installation of historic streetlights.
E. Control System
All new streetlighting in the DME service area shall have a control node installed which, at a
minimum, will turn the light on and off according to ambient light conditions (photocell control)
and shall be compatible with the CityTouch lighting control system. See Table 7.2-C shown below.
Where street lighting is installed by the developer, DME shall provide and install control nodes at
the developer’s expense. DME will commission the control nodes into the CityTouch program.
Where streetlighting is served by other electric utilities than DME, DME does not require or install
control nodes.
Table 7.2-C: CityTouch-compatible control node models
Model Number Voltage (V) Use Function
LLC7290 120 – 277 Cobra head lights Photocell controller
LLC7294 347 – 480 High-voltage cobra head lights Photocell controller
LLC7291 120 - 277 Post-top lights Astro-clock
(GPS location-based timers)
F. Dimming and Light Trespass
The City adheres to ANSI RP-8 lighting levels for all streets except local residential streets with speed
limits of 30 mph or less. Lighting that has been designed to ANSI RP-8 cannot be dimmed without
diminishing the lighting level which, by definition, no longer meets the RP-8 standard. Thus, all
streetlighting that is not in residential neighborhoods with speed limits of 30 mph or less will be
maintained at full brightness.
On local residential streets with speed limits of 30 mph or less, the streetlights may be dimmed by
resident request at specific locations due to light pollution concerns by residents. DME will dim
residential streetlights down as low as 60%.
The City also reserves the right to install house side shields (available only on cobrahead lights) and
make other reasonable modifications to the luminaires to minimize impacts to the residents at the
DME’s discretion.
G. Migratory Birds and Other Flying Species
DME will dim residential streetlights down as low as 50% during select animal migration or activity
periods as specified by the City Environmental Services & Sustainability Department.
Section 7: Streetlight Design Criteria
7.3 Developer and DME Responsibilities
7.3.1 Construction Requirements
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H. International Dark Sky Association
DME installs and maintains two types of streetlight luminaires (light fixtures), post-top and
cobrahead. The cobrahead light fixtures are endorsed by the International Dark Sky Associate (IDA)
which makes recommendations on lighting with minimal up-light. The existing post-top lighting
fixtures are not IDA endorsed, however an acceptable IDA approved alternate is being considered
for all residential streets with speeds less than 30 mph.
7.2.4 Construction Requirements
Streetlight construction (e.g. conduit, wiring, etc.) shall follow the DME Standard Construction Drawings,
stated below:
A. DSL-ARM
B. DSL-STD
C. DSL-12A
D. DSL-20C (Legacy)
E. DSL-35C
F. DSL-20S
G. DSL-35SE
H. DSL-35SE2
I. DSL-35SBK
J. DSL-35SBK2
E.K. DSL-35SBD
Conduit runs should not exceed 700 feet between pulling locations. When bends total 180 degrees conduit
runs should be limited to 500 feet or less. No run of conduit should have more than 360 degrees of total
bend between pulling points.
The total length of a single lighting circuit at 120V should be less than 1,000 feet, the total length of a single
lighting circuit at 240V should be less than 2,000 feet, and the total length of a circuit at 480V should be
less than 4,000 feet unless circuit design and loading has been validated by engineering.
Additional design information may be found in the TxDOT Highway Illumination Manual.
7.3 Developer and DME Responsibilities
7.3.1 Highways and Streets (except local residential streets with speed ≤ 30 mph)
Developer is responsible for streetlighting design that meets the requirements of ANSI RP -8 for the
appropriate roadway characteristics. A photometric (lighting) study shall be required. The final design must
be approved and stamped by a PE licensed in the State of Texas licensed professional engineer. Final design
must also be approved by DME Engineering.
Lighting levels, placement, and compliance with ANSI RP-8 must be verified and documented with lighting
design software. At a minimum, documentation shall be provided to DME Engineering showing:
A. Street geometry (width, number of lanes, median size)
Section 7: Streetlight Design Criteria
7.3 Developer and DME Responsibilities
7.3.2 Local Residential Streets (with speed limits ≤ 30mph)
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B. Street classifications (arterial, collector, etc.)
C. Pedestrian activity classification
D. Criteria levels applied (illuminance vs. luminance method, and levels)
E. Lighting placements (median, side, parallel, staggered)
F. Maximum separation distance*
As an alternative to displaying the maximum separation distance as stated in 7.3.1.F above, a layout drawing
of the project may be provided with calculation grid values and/or light level isolines indicating that the
installation meets the applicable requirements.
For TxDOT projects, the design contractor will provide specific lighting requirements, if any. The design
package should dictate where lighting should be placed and what types of poles and fixtures should be
used.
For City initiated projects, the City’s Engineer or their contractor will design the street lighting and submit
to DME Engineering for approval. Once approved, the city’s contractor will perform all civil work, and pull
wiring and install streetlights and poles. DME will provide service point s as needed. DME will also install
and commission control nodes for interconnection with CityTouch.
A monthly maintenance, repair, and usage fee will be charged to the City thereafter for all streetlights on
public streets per current DME rates.
7.3.2 Local Residential Streets (with speed limits ≤ 30mph)
The Developer (or DME if DME is responsible for the given project) is responsible for the design and layout
of streetlights at all intersections, cul-de-sacs, and no more than 250 feet between. DME Engineering shall
approve the final design. Once the project is approved and permitted, the Developer is responsible for
providing all civil work including grading, trenching, installation of conduit and pull-boxes, etc.
DME is responsible for installation of wire, streetlights and poles, and service points. DME will charge an
initial installation cost to the developer based on the number of lights.
A monthly maintenance, repair, and usage fee will be charged to The City thereafter for all streetlights on
public streets per current DME rates.
For City initiated projects, the City’s Engineer or their contractor will design the street lighting and submit
to DME for approval. Once approved, the city’s contractor will perform all civil work, and pull wiring and
install streetlights and poles. DME will provide service points as needed. DME will also install and
commission control nodes for interconnection with CityTouch.
For private streets and drives (where the City of Denton does not take ownership of the roadway or
streetlights), one of the following will occur:
A. If non-standard lights are installed, DME will provide a metered service point. Developer is
responsible for installation of entire streetlighting system. Designated customer (individual, HOA,
etc.) will be responsible for monthly power costs and all maintenance. OR
B. If standard DME lighting is installed, Developer is responsible for all civil work (grading, trenching,
installation of conduit, etc.) and installation of poles and streetlights. DME will pull wires and
connect the lights at the Developer’s expense. Designated customer (individual, HOA, etc.) will be
responsible the monthly streetlight power and maintenance rates. OR
C. Exceptions to this rule must be agreed upon by all parties in a formal agreement.
Section 7: Streetlight Design Criteria
7.3 Developer and DME Responsibilities
7.3.4 Streetlighting in Non-DME-Served Areas
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7.3.3 Streetlighting in Non-DME-Served Areas
Standard streetlights have been approved by the City as listed in the General Requirements section of this
manual. Electric utilities other than DME may or may not be able to provide the same luminaires. Non -
standard lights will not be maintained by DME or the City. DME will provide, install, maintain, and repair
standard the City streetlights at the Developer’s expense. The electric service provider will charge the City
according to the rates agreed upon between the City and the electric service provider.
For streets in non-DME service territories, Developer should coordinate with the electric utility, DME, and
the City at the earliest stage of development to determine and agree upon the following:
A. Developer, City/DME, and Customer responsibilities
B. Service points and project design
C. Mode of disconnect for safe maintenance (e.g. in-line fuses, etc.)
D. Mode of billing (metered usage, monthly rate, etc.)
E. Designated customer/developer responsible for fees
F. Other concerns as applicable
7.3.4 Customer/Citizen Requests for addition/removal of Streetlighting
When additional/modified/decreased lighting is requested by a customer, DME will perform an analysis of
the lighting to determine if the modifications would provide added safety, visibility, and aesthetic value to
a location. Light intrusion, cost, and feasibility will also be considered. At DME’s discretion, lighting may
be added or modified to bring the streetlighting closer in line with this manual or meet other specific
concerns.
In coordination with the City’s Environmental Services & Sustainability Department, DME may dim
streetlights in residential areas to no lower than 50% brightness.Streetlights managed by DME are funded
through the City’s Capital Improvement Projects (CIP) process. As concerns are identified and provided to
DME via citizen comments, staff input, and/or City Council direction the requests are directed to DME
Engineering for technical evaluation. The technical evaluation is to determine if the modifications would
provide added safety and visibility according to national and local standards and ordinances. Light
pollution/intrusion, cost, feasibility, and aesthetic value are also considered. At the conclusion of the
technical evaluation, DME Engineering submits a recommendation for or against inclusion of the project in
the CIP.
DME will maintain the list of all requested modifications and prioritize those that have been recommended
for inclusion within the upcoming CIP. Some or all of the highest priority projects will be programmed into
the upcoming budget based on availability of funds.
Requests for dimming will be considered in residential areas, and in coordination with the City’s
Environmental Services & Sustainability Department, DME may dim streetlights in residential developments
to no lower than 50% brightness. Cobrahead streetlights along other local, collector, and arterial streets
may not be dimmed due to safety and regulatory requirements.
Section 7: Streetlight Design Criteria
7.3 Developer and DME Responsibilities
7.3.4 Customer/Citizen Requests for addition/removal of Streetlighting
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Section 8: Environmentally Sensitive Areas
Design Criteria
8.1 Overview
The purpose of Section 8 - Environmentally Sensitive Areas (ESAs) Design Criteria is to provide the technical
design criteria needed to achieve compliance with DDC Subchapter 7, Section 7.4. The goal is to provide
basic guidance for implementing certain components of ESA plans, such as ESA Field Assessments. While
the intent of this section is to assist applicants and developers with ESA requirements, full responsibility and
liability for proper design and compliance with DDC Section § 7.4 remains with the developer or applicant.
Users of this Manual should be knowledgeable and experienced in environmental surveys, inventorying and
restoration (See the basic requirements for a qualified person in this section).
This section does not provide complete guidance for Alternative ESA Plans, as those plans are developed
through a discretionary zoning process, due to special circumstances or conditions that apply to the parcel
for which the deviation is sought. The Alternative ESA Plan procedure is described in DDC Section § 2.8.4.
The following documents govern the design criteria in this section and in the event of a conflict between
any of these documents, the following order of precedence applies:
A. The Denton Development Code;
B. Floodplain Development Checklist;
C. ESA Field Assessment Checklist;
D. Alternative Environmentally Sensitive Area Checklist;
E. The iSWM Landscape Technical Manual; and
F. The National Wetland Plant List.
8.2 ESA Identification
8.2.1 The Official ESA Map
A. To locate potential ESAs, the applicant shall use the City of Denton’s Official ESA Map.
B. The legend in the Official ESA Map displays the types of ESAs and their designations.
1. The City recognizes four types of ESAs, as detailed further in Appendix D of this Manual:
a. Cross Timbers Upland Habitat;
b. Water Related Habitat;
c. Riparian Buffer ESA; and
d. Floodplain ESA.
2. ESAs can have one of two following designations
a. Designation Confirmed
ESA assessments expire after 24 months or if the natural conditions of the ESA have
been significantly altered; the applicant shall check the date that the assessment was
approved to ensure that the current designation is correct
Section 8: Environmentally Sensitive Areas Design Criteria
8.3 ESA Field Assessments
8.3.3 ESA Field Assessor Qualifications
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b. Not Assessed or Assessment Expired
C. Areas determined to be ESAs during field assessments are added to the Official ESA Map.
D. Areas determined not to be ESAs during field assessments may potentially be removed from the
Official ESA Map.
E. Because ESA criteria applies to all land and development, it may be necessary to perform ESA Field
Assessments in areas not identified on the Official ESA Map. This could be due to site conditions or
current aerial photography (among other reasons). Field assessments are required when there is
reasonable evidence that ESAs, as depicted on the Official ESA Map, may not be accurate. ESA field
assessments that require map adjustment shall supersede the Official ESA Map in determining what
areas of a proposed development are subject to the requirements of Section 7.4 (Environmentally
Sensitive Areas) of the DDC.
8.3 ESA Field Assessments
8.3.1 ESA Field Assessor Qualifications
ESA features shall be identified during the ESA Field Assessment by a qualified person . Minimum
requirements to be considered a qualified person are:
A. Have a bachelor’s degree in ecology or similar field of study; or
B. Be a certified/trained wetland scientist; or
C. Have similar qualifications in plant identification, soil classification, and hydrology.
1. The City accepts professional licenses and certifications such as Professional Wetland
Scientist (PWS), Wetland Professional in Training (WPIT), and continuing professional
education courses from applicable programs.
8.3.2 ESA Forms
All ESA submittals shall utilize the City’s Assessment Forms:
A. Cross Timbers Upland Habitat Assessment Form
B. Floodplain ESA Assessment Form
C. Riparian Buffer ESA Assessment Form
D. Water-Related Habitat Assessment Form
8.3.3 ESA Field
ESA Field Assessments shall contain, at a minimum:
A. Assessor qualifications;
B. Comprehensive reports appropriate for each ESA type and feature assessed, pursuant to the ESA
Assessment Form for each type of ESA present on the project;
C. A project narrative with details of the assessment, including, but not limited to:
1. A brief description of the project’s nature
Section 8: Environmentally Sensitive Areas Design Criteria
8.4 ESA Preservation Requirements
8.3.3 ESA Field
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2. Descriptions and locations for ESAs identified on the Official ESA Map
3. Descriptions and locations of any ESAs determined to be present
a. Include detailed reasoning as to why ESA features were identified
b. Include colored photographs as supporting evidence
4. Location and boundaries of areas misidentified as ESAs by the City’s Official ESA Map
a. Include detailed reasoning as to why the Official ESA Map is incorrect
b. Include colored photographs as supporting evidence
D. Shapefiles identifying both confirmed ESAs, and ESA locations that should be removed. The
following geographic information shall be used:
1. Geographic Coordinate System: GCS North American 1983
2. Datum: D North American 1983
3. Prime Meridian: Greenwich
4. Projected Coordinate System: NAD 1983 State Plane Texas North Central FIPS 4202 Feet
5. Projection: Lambert Conformal Conic
E. A site map or series of maps, that delineate the boundaries and types of ESAs as indicated on the
Official City of Denton ESA Map; and
F. A site map that delineates the boundaries and types of ESAs that were assessed; this may differ
from the Official ESA Map.
1. Indicate the reach of each assessment and locations of photographs taken on a map; this
may be its own map.
8.4 ESA Preservation Requirements
Where ESAs are identified, whether through field assessments or an existing, confirmed designation, ESA
protection must be installed.
A. ESA protection shall consist of safety or other protective fencing established at the perimeter of
any ESAs. Where a protected tree that qualifies for preservation is located near the ESA perimeter,
protective fencing shall be extended to encompass the tree within ESA boundaries. Where ESA
protective fencing has been extended to encompass preserved trees, it shall be installed at the
dripline of the tree’s dripline.
B. Land-clearing to allow for the installation of ESA protection fencing shall occur upslope of the
ESA perimeter (that is, on the outside perimeter), and shall not exceed a width of four feet. It shall
not encroach into the dripline or critical root zone of any tree to be protected.
C. Protective fencing should be a minimum of four (4) feet in height and consist of plastic safety
fencing or other approved fencing material. Protective fencing shall be supported by posts with a
maximum spacing of eight (8) feet.
D. Protective fencing shall be placed downslope of any perimeter controls for erosion and
sedimentation.
Section 8: Environmentally Sensitive Areas Design Criteria
8.4 ESA Preservation Requirements
8.4.1 ESA Inspections
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8.4.1 ESA Inspections
A. Initial Inspections
1. An initial inspection shall must be conducted prior to: approval of permits, issuance of a
Notice-to-Proceed, or any commencement of land disturbing activities. commencing land-
disturbing activities for the approval of permits or issuance of a Notice-to-Proceed.
2. ESA protective fencing shall be inspected against corresponding site plans for proper
placement and installation.
B. Routine Inspections
1. To ensure compliance with ESA criteria, ESA inspections shall be conducted after land-
disturbing activities have commenced to ensure compliance with ESA criteria, and may be
conducted during all phases of development, including:
a. Cut and fill;
b. Demolition;
c. Clearing and grading;
d. Grubbing;
e. Stockpiling;
f. Installation of utility infrastructure;
g. Construction; and
h. Vertical building.
2. Routine inspection items shall include maintenance, repair, and replacement of ESA
protective fencing. Damaged ESA fencing shall be repaired or removed and replaced during
all phases of development until final inspection.
3. During development, access to the ESA shall be prohibited and the ESA shall be preserved
in its original state.
4. The disposal of any waste material into the ESA is prohibited.
5. Siltation or sedimentation to the ESA is prohibited; any that occurs shall and must be
addressed in a timely manner.
a. Siltation or sedimentation impacting up to 0.10 acres of any ESA must be removed by
hand or equivalent method, as approved by the City.
b. Siltation or sedimentation impacting 0.10 acres or more of any ESA must be addressed
through an Alternative ESA Plan.
6. The permanent loss of any native vegetation or other ESA features is prohibited:
a. Native vegetation loss impacting up to 0.10 acres of any ESA or the loss of up to two
(2) trees, shall be replaced in-kind.
b. Native vegetation loss impacting 0.10 acres or more of any ESA , or the loss of three (3)
trees or more, must be addressed through an Alternative ESA Plan .
a. If the loss of any native vegetation or ESA feature affects up to 0.10 acres of any ESA :
i. The ESA must be returned to its previous state through in-situ restoration; and
ii. A restoration plan shall be provided
Section 8: Environmentally Sensitive Areas Design Criteria
8.5 Restoration Plans for Permitted Uses and Activities
8.5.2 Restoration Plan Requirements
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These requirements apply when development activities result in the loss of two (2) or
less trees protected as per Section 8.4.A of this Manual.
b. If the loss of any native vegetation or ESA feature affects 0.10 acres or more of any ESA,
the developer may be required to initiate one (1) of the following compliance activities,
based on the extent of damage to the ESA(s) and staff discretion:
i. Cease all development activities and provide a restoration plan to the City for
approval; or
ii. Cease all development activities and pursue mitigation through an Alternative ESA
Plan.
These requirements apply when development activities result in the loss of three (3) or
more trees protected as per Section 8.4.A of this Manual.
8.5 Restoration Plans for Permitted Uses and Activities
8.5.1 Restoration Plan Requirements
Permitted uses and activities for each ESA are described in DDC Sections §§ 7.4.6-7.4.8. For permitted uses
and activities, the applicant shall provide a restoration plan which, at a minimum, includes:
A. Locations and descriptions of any areas within the ESA that will require restoration ;
B. Locations and descriptions of temporary stabilization measures;
C. Descriptions of restoration activities including, but not limited to:
1. Erosion minimization;
2. Native plant restoration;
3. Invasive vegetation removal, etc.
D. Schedule or timeline for restoration activities; and
E. Descriptions and locations of permanent seed mixes and/or plantings.
8.5.2 Restoration Activities and Alternative ESA Plan Mitigation
This subsection applies to approved Restoration Plans and, and mitigation for Alternative ESA Plans.
A. Restoration and/or mitigation shall be initiated immediately whenever development activities have
permanently or temporarily ceased within the ESA.
1. Development activities have permanently ceased when land-disturbing activities within the
ESA have been completed.
2. In the context of this provision, “immediately” means as soon as practicable, but no later than
the end of the next workday, following the day when development activities have temporarily
or permanently ceased.
B. Alternative ESA Plan Mitigation, unless alternatively specified in the approved plan, shall also be
initiated immediately whenever development activities have permanently or temporarily ceased
within the ESA.
1. Mitigation for disturbed ESAs, by area, must be one-to-one by ESA type.
Section 8: Environmentally Sensitive Areas Design Criteria
8.5 Restoration Plans for Permitted Uses and Activities
8.5.2 Restoration Activities and Alternative ESA Plan Mitigation
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C. Restoration and/or mitigation shall be completed prior to close-out or issuance of final Certificate
of Occupancy.
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Section 9: Design Deviations
9.1 Overview
9.1.1 General
All developments within the City and its extraterrestrial jurisdictions shall conform to the design criteria
established in this DCM. In the event that a development cannot comply with the design criteria established,
a design deviation process is used to evaluate, document, and approve proposed alternative methods.
Any deviation from the required design criteria for design of facilities outlined in this DCM must be
submitted as a design deviation request to the City’s Engineer and Department Reviewer, prior to
incorporating it into the final design of a project.
9.2 Design Deviation Procedure
9.2.1 Request for Design Deviation Submittal and Processing
A. All design deviation requests must be submitted as a formal request to Development Project
Facilitation using the ‘Request for Design Deviation Form’ included in Appendix B, along with
supporting documentation.
1. The ‘Request for Design Deviation Form’ shall be filled out completely with exception of the
portions noted as “For Use by City”.
2. Supporting documentation shall include:
a. All pertinent information on the facilities involved or to be involved. The specific portion
of this DCM, policies, or design standard(s) for which a design deviation is sought;
b. Description(s) of all other design alternatives which the applicant has evaluated in
attempts to comply with the design criteria prior to the request for design deviation;
and
c. A statement that provides justification for the requested design deviation and how it is
the necessary and optimal solution when compared with reasonable alternatives for the
scenario presented.
3. Design deviation requests that do not contain the required Request for Design Deviation
Form and supporting documentation are incomplete and will not be reviewed.
B. The request and supporting documentation shall be submitted concurrently with Civil Engineering
Plans, Zoning Compliance Plans, Planned Development, or Specific Use Permit submittal.
9.2.2 Criteria for Granting of Design Deviation
A. The review of a design deviation request by the City’s Engineer and Department Reviewer shall
assess whether the request:
1. Clearly demonstrates an exceptional hardship which prevents the design criteria from being
met. This hardship cannot be solely self-imposed and should be based upon physical
characteristics of the property, environmental conditions, or existing conditions created by
surrounding development;
Section 9: Design Deviations
9.3 Revocation of an Approved Design Deviation
9.1.1 General
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2. Is not detrimental to the public welfare;
3. Does not adversely impact the operations of the system or the public facility in question;
4. Is supported by a signed and sealed engineering analysis performed by a PE Llicensed
Professional Engineer in the State of Texas, if requested by the Engineering Department; and
5. Shall not be solely to mitigate a financial hardship.
B. The decision of the City’s Engineer and Department Reviewer is guided by the criteria for approval,
but is ultimately discretionary based on their engineering judgment and professional experience.
C. All approved design deviation requests shall be signed by the City’s Engineer and Department
Reviewer, before implementation.
D. The decision of the City’s Engineer and Department Reviewer to grant a design deviation shall not
relieve the applicant’s Engineer of the professional obligation and responsibility to ensure any
approved alternatives to the use of the material, design, or method of construction are fit for the
intended purposes of the facilities at issue.
E. If a design deviation request is denied by the City’s Engineer and Department Reviewer, the
applicant may consider reviewing alternatives and resubmitting the application with more
information as is deemed necessary, for re-evaluation by the City’s Engineer and Department
Reviewer.
9.3 Revocation of an Approved Design Deviation
9.3.1 Applicability and Procedure
A. An approved design deviation request may be revoked by the City’s Engineer and Department
Reviewer, if:
1. The supporting documentation that the City’s Engineer and Department Reviewer used to
review and approve the design deviation request is materially altered or updated. Any
individual or entity that receives an approved design deviation request must provide the
City’s Engineer and Department Reviewer with any change in plans or conditions to the
project that affect the requested deviation as soon as practicable after any such change
occurs. Failure to provide these updates may result in design deviation revocation by the
City.
2. The applicant is shown to have provided inaccurate or incomplete information during review
of the design deviation request.
3. The City determines there is a failure to comply with any term, condition, or requirement
applicable to a design deviation;
B. A decision to revoke a design deviation is effective immediately. Notice of the decision shall be
communicated to the applicant.
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Appendix A: Example Stormwater Facility Checklists
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INSPECTION CHECKLIST FOR SIMPLE DETENTION BASIN
Facility Name: Facility Agreement Number:
Basin/Pond Number: Inspected By: Date:
Type of Inspection: Annual , Quarterly , Monthly , Routine , or Storm Event , (# days since event )
Basin Conditions:
1. Is there standing water or wet spots? Yes No Comments
2. Does sides or bottom show signs of erosion, settling, cracking, etc? Yes No Comments
3. Does dam or emergency spillway show signs of erosion, settling,
cracking, or other problems Yes No Comments _____________________________________
4. Is there evidence of animal burrowing in dam? Yes No Comments
5. Is there evidence of changes in shape or volume of basin? Yes No Comments
6. Do vegetated areas need mowing? Yes No Comments
7. Are there trees or woody growth in dam? Yes No Comments
8. Are there areas that need to be re-vegetated? Yes No Comments
9. Is there any accumulation of silt, trash, debris or litter in the basin? Yes No Comments
10. Are there any other basin maintenance activities needed? Yes No Comments
Structural Components:
1. Are pipes, channels, trash racks, etc. free of obstructions? Yes No Comments
2. Are pipes, spillway or trash racks in need of repair? Yes No Comments
3. Is the low flow or trickle channel in need of repair? Yes No Comments
4. Is the outfall channel in need of repair? Yes No Comments
5. Are there any other structural maintenance activities needed? Yes No Comments
Plan for correcting deficiencies: Signature:
Date:
Owner’s Representative
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ENGINEER’S CHECKLIST FOR STORMWATER
FACILITY MAINTENANCE AGREEMENT
Please attach additional sheets as necessary for comments and descriptions. Fit all sheets to 8½” x 11”.
ORGANIZATION INFORMATION
1. Company (Applicant) Address:
2. Contact’s Information:
Contact Name
Mailing Address
Telephone
Number(s) Email
3. Execution Information:
Signatory’s Name
Mailing Address
Telephone Number(s)
Email
4. Property Location:
(Note: If the property has not been addressed, please enter the legal description)
5. Associated Plat Numbers:
(Note: if request is related to multiple plat applications, please list each individually)
6. Associated Building Permit Numbers:
(Note: if request is related to multiple permits, please list each individually)
AGREEMENT & ATTACHMENT INSTRUCTIONS
If the property owner is a corporation, the agreement must be signed by a person who is duly authorized to bind the corporation including, but not limited to, a
President or Vice President. . If a partnership, the agreement must be signed by the managing partner. If the applicant is a sole proprietor, he/she signs the
agreement on behalf of him or herself. Additionally, for corporations and partnerships, a copy of the Articles of Incorporation, showing signature authority
for whoever signs the agreement must also be submitted (Note: Applicants may also submit a board resolution or power of attorney authorizing an agent
or assign to sign on behalf of the property owner. The agreement must be completely filled out and three copies submitted to the Planning and Development
Department. Signatures on all three agreement drafts must be original and notarized. Lastly, please submit a copy of the deed for the noted property.
NOTE: Agreement and all attachments should be submitted on 8 ½” x 11”.
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Yes No N/A Comments/Descriptions Page 2 of 3
1. Legal Agreement – Standard agreement form provided by
the City.
2. Exhibit “A” - Legal Description (Attached)
A. Metes and Bounds.
B. Surveyor’s Drawing, with seal affixed and marked as
“Drainage Easement”.
C. Preliminary Plat.
3. Exhibit “B” - Design Plan and Specifications (Attached)
A. Design Calculations – in accordance with iSWM.
B. Schematic Plan (See Example Detention Plan Schematic)-
prepared in accordance with approved construction plans:
• Plan View showing critical structural elements .
• Critical structural elements are clearly labeled in layman terms.
• Profile including a longitudinal section showing all critical
structural elements with elevations.
• Cross-sections as needed to show size and general grading.
NOTE: All Schematics should be submitted on 8 ½” x 11”.
C. Landscaping shown per approved Landscape Plans.
4. Exhibit “C” - Operations and Maintenance Plan (Attached)
A. Routine Maintenance Specifications:
1. Mowing as needed to control weeds and woody plants.
2. Trash removal from critical structural elements.
3. Additional maintenance.
B. Non-routine Maintenance Activities:
1. Bank repair and stabilization.
2. Re-vegetation - required when 30% or more of area is
unprotected.
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Yes No N/A Comments/Descriptions Page 3 of 3
3. Sediment removal from the detention/retention facility when:
• Detention basin – when water depth is reduced 25%
or more, or basin does not drain within 72 hours.
• Retention pond – when water depth is 4’ or less.
• Sediment traps/forebay – when depth is reduced by 50% or more.
4. Structural repair/replacemen t for all damaged or deteriorated
structures, trickle channel, trash rack, etc.
5. Mechanical equipment repairs.
6. Other maintenance Activities.
5. Exhibit “D” - Maintenance Checklist *
A. Covers ordinary needs, in layman terms.
B. Structural components labeled consistent with Schematic Plan.
*See attached Inspection Checklist for Detention Basin
NOTE: All Exhibits should be submitted on 8 ½” x 11”.
I certify that this Storm water Facility Maintenance Agreement, checklist, required attachments, and additional comments, was
prepared under m y responsible supervision and that the information presented on this checklist and attachments is correct to
the best of m y k nowledge. I also understand that an acceptance of this plan b y the City does not waive any City standards or
requirements unless a specific waiver request has been submitted and approved.
(seal)
Signed Date _
Print Name:
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Appendix B: Design Deviation Request Form
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Note: Request the fillable Deviation Request form from your Facilitator.
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Appendix C: Poles and Luminaires - Standard
Lighting Fixtures
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Figure C.1: Residential Lighting – 20-ft. concrete aggregate pole woth post-top luminaire
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Figure C.2: General Street Lighting – Wood (distribution) pole with single-mast arm
and cobra head luminaire
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Figure C.3: General Street Lighting – 35-ft. white concrete pole with single or double-mast arms
and cobra head luminaire
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Figure C.4: Historic District Lighting – 12-ft. concrete aggregate pole woth post-top luminaire
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Figure C.5: Alternate General Streetlighting – 35-ft. dark gray steel pole with single or double mast
arms and new cobra head luminaire.
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Appendix D: Types of Environmentally
Sensitive Areas
The City of Denton has identified four distinct ESAs - Floodplains, Riparian Buffers, Water-Related Habitat,
and Cross Timbers Upland Habitat. Native plants associated with each ESA are listed below. A complete list
of Native Plants is included in Appendix E.
A. Floodplain ESAs exist on the terraced banks surrounding waterways where the land is subject to
flooding. The City of Denton uses the most current FEMA Flood Insurance Rate Map (FIRM) to
define boundaries of protected Floodplain ESAs. Areas designated as 1% Annual Chance Floodplain,
labeled on the FIRM as Zone A or Zone AE, would be classified according to existing conditions as
developed or undeveloped floodplains. Areas identified as undeveloped floodplains become
protected Floodplain ESAs. Floodplain ESA habitat is often an extension of the more sensitive
Riparian Buffer. Typical Floodplain ESA habitat is dominated by tree species that can tolerate
intermittent flood events.
B. Riparian Buffer ESAs are adjacent to bodies of water such as wetlands, streams, rivers, ponds and
lakes. A healthy functioning Riparian Buffer will have a mix of woody and herbaceous plants.
Streams, creeks, and rivers are classified by their duration of flow; there are three types:
1. Perennials flow continuously except during severe drought.
2. Intermittent flow only for a portion of the year seasonally or after rainfall.
3. Ephemerals only flow in direct response to rainfall and will often be dry.
C. Water-Related Habitat ESAs are split into four categories: wetlands, bottomland hardwood forests,
springs, and deepwater habitats. These areas are typically found in low-lying areas near bodies of
water but can also be isolated low-lying areas that meet characteristics of water-related habitats.
These characteristics will likely include hydric soils, signs of hydrology, and hydrophytic vegetation.
1. Wetlands can be isolated or adjacent and will have all three wetland indicators present: hydric
soils, hydrology, and hydrophytic vegetation. Adjacent wetlands are connected to a
jurisdictional water body, such as a lake or river, and are subject to federal regulation under
the Clean Water Act; isolated wetlands are not connected to surface water bodies and are
regulated at the state or city level.
a. An area shall be classified as a wetland if it meets the Army Corps of Engineers three
parameter technical criteria as outlined in the Corps of Engineers 1987 Wetlands
Delineation Manual (Section D. Routine Determinations).
b. The recommended routine method assumes sufficient hydrology and hydric soils if the
area in question has over 50% vegetative cover of hydrophytic (facultative-wet and/or
obligate as listed in the National Wetland Plant List (NWPL), Great Plains Region, and a
clearly defined boundary between the hydrophytic and upland plant communities.
c. Permitted water quality ponds, roadside ditches, and ponds fed by wells or other
sources of artificial hydrology are not considered wetlands.
d. The Wetlands Classification System (WCS) includes five major Systems: Marine,
Estuarine, Riverine, Lacustrine, and Palustrine. The first four include both wetlands and
deepwater habitats, but the Palustrine only includes wetland habitats. In North Central
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Texas, the predominant wetland types are Riverine, Lacustrine and Palustrine, and are
detailed in Table 9-A below.
Table D-1: Predominant Wetland Types of North Central Texas
Wetland Type Major Characteristics
Riverine Wetlands and deepwater habitats within a stream or river channel; includes
oxbow lakes and sloughs; periodically influenced by flooding
Lacustrine Wetlands and deepwater habitats associated with large lakes and reservoirs;
situated in basins that lack significant tree or shrub cover
Palustrine All non-tidal wetlands dominated by trees, shrubs, or persistent plants;
includes Bottomland hardwood forests, which is the most widespread type of
wetland in Texas and includes trees like pecan, sugarberry, and black willow.
2. Bottomland Hardwood Forest ESAs consist of deciduous forested wetlands and river
bottoms. Denton defines this habitat as areas containing at least 50 percent of native trees
and understory vegetation typically found in a bottomland hardwood forest.
3. Springs are points of natural groundwater discharge that produce flow, a pool of water, or
maintain hydrophytic plant communities (refer to Facultative-wet or Obligate plant species
as listed in the in the National Wetland Plant List (NWPL), Great Plains Region. Physical
indicators include pooling of water, hydrophytic plants, or the presence of a water temperate
gradient in a creek or pool.
4. Deepwater habitats are permanently flooded lands lying below the deepwater boundaries of
wetlands. Deepwater habitats include environments where surface water is permanent and
often deep, so that water, rather than air, is the principal medium within which the dominant
organisms live, whether or not they are rooted in, or attached to, the substrate. As in
wetlands, the dominant plants are hydrophytic.
Wetlands and deepwater habitats are defined separately because traditionally the term wetlands
has not included deep, permanent water; however, both must be considered an ecological
approach to classification. The boundary between wetland and deepwater habitats in the riverine
and lacustrine systems lies at a depth of 2 meters (6.6 feet) below water; however, if emergent,
shrubs or trees grow beyond this depth, their deep-water edge is the boundary.
D. Cross Timber Upland Habitat ESA are deciduous forest interspersed with prairie grasses. It can be
split into four vegetative sub-regions. The predominate sub-region found in Denton, TX is the
Eastern Cross Timbers. The Eastern Cross Timbers is dominated by Post Oaks and Blackjack Oaks.
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Appendix E: Native Plants for ESAs
Table E-1: Native Plants List – Canopy Trees
Common Name Botanical Name
Red maple Acer rubrum
Texas buckeye Aesculus arguta
Pecan Carya illinoiensis
Texas hickory (Black hickory) Carya texana
Net-leaf hackberry Celtis reticulata
Desert willow Chilopsis linearis
White ash Fraxinus americana
Green ash Fraxinus pennsylvanica
Texas ash Fraxinus texensis
Black walnut Juglans nigra
Ashe juniper (Mountain cedar) Juniperus ashei
Eastern red cedar Juniperus virginiana
Sweetgum Liquidambar styraciflua
Texas red oak Quercus buckleyi
Escarpment live oak Quercus fusiformis
Bur oak Quercus macrocarpa
Blackjack oak Quercus marilandica
Chinquapin oak Quercus muehlenbergii
Shumard oak (Red oak) Quercus shumardii
Bigelow oak Quercus sinuata var. breviloba
Post oak Quercus stellata
Live oak Quercus virginiana
Black willow Salix nigra
Western soapberry Sapindus saponaria var.drummondii
Chittamwood (Gum bumelia) Sideroxylon lanuginosum
Winged elm Ulmus alata
American elm Ulmus americana
Cedar elm Ulmus crassifolia
Slippery elm Ulmus rubra
Prickly ash (Texas hercules club) Zanthoxylum hirsutum
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Table E-2: Native Plants List – Small Trees and Shrubs
Common Name Botanical Name
White buckeye (Texas buckeye) Aesculus arguta
Common beebush (Whitebrush) Aloysia gratissima
Indigobush (False Indigo) Amorpha fruticosa
Roosevelt-weed Baccharis neglecta
Argarita (Mahonia) Berberis trifoliolata
American beautyberry Callicarpa americana
Buttonbush Cephalanthus occidentalis
Eastern redbud Cercis canadensis
Texas redbud Cercis canadensis var. texensis
Roughleaf dogwood Cornus drummondii
Downy hawthorn Crataegus mollis
Greenhawthorn Crataegus reverchoni
Common persimmon Diospyros virginiana
46 Elbowbush Forestiera pubescens
Carolina buckthorn Frangula caroliniana (Rhamnus caroliniana)
Possum-haw Ilex decidua
Yaupon Holly Ilex vomitoria
Texas Walnut (Nogalito, Little walnut) Juglans microcarpa
Mock orange Philadepphus pubescens
Chickasaw plum Prunus angustifolia
Oklahoma plum (Sand plum) Prunus gracilis
Mexican plum Prunus mexicana
Hog plum Prunus rivularis
Hoptree Ptelea trifoliata var. mollis
Flameleaf sumac Rhus copallinum
Smooth sumac Rhus glabra
Buffalo currant Ribes aureum
White prairie rose Rosa foliolosa
Elderberry Sambucus nigra var. canadensis
Eve`s necklace Sophora affinis
Coralberry Symphoricarpos orbiculatus
Mexican buckeye (Texas buckeye) Ungnadia speciosa
Farkleberry Vaccinium arboreum
Rusty blackhaw Viburnum rufidulum
Arkansas yucca Yucca arkansana
Lotebush Ziziphus obtusifolia
Peppervine Ampelopsis arborea
Heartleaf ampelopsis Ampelopsis cordata
Pipevine Aristolochia tomentosa
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Table E-2: Native Plants List – Small Trees and Shrubs
Common Name Botanical Name
Rattan vine Berchemia scandens
Trumpet vine Campsis radicans
Ballonvine Cardiospermum halicacabum
Cowitch (Ivy-treevine, sorrelvine) Cissus incisa
Old-man's-beard Clematis drummondii
Bluebill (Leather-flower) Clematis pitcheri
Carolina snailseed Cocculus carolinus
Sharp-pod morning glory Ipomoea cordatotriloba var. cardatrtriloba
Cotton morning glory Ipomoea cordatotriloba var. torreyana
Coral honeysuckle Lonicera sempervirens
Virginia creeper Parthenocissus quinquefolia
Blackberry Rubus oklahomus
47 Dewberry Rubus trivialis
Greenbriar Smilax bona-nox
Bristly greenbriar Smilax tamnoides
Summer grape Vitis aestivalis
Mustang grape Vitis mustangensis
Riverbank grape Vitis riparia
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Table E-3: Native Plants List – Grasses
Common Name Botanical Name
Elliott's bentgrass (Annual tickle grass) Agrostis elliottiana
winter bentgrass (Tickle grass) Agrostis hyemalis
Big bluestem Andropogon gerardii
Bushy bluestem Andropogon glomeratus
Splitbeard bluestem Andropogon ternarius
Broomsedge bluestem Andropogon virginicus
Oilfield threeawn (Prairie threeawn) Aristida oligantha
Purple threeawn Aristida purpurea
Silver bluestem Bothriochloa laguroides
Sideoats grama Bouteloua curtipendula
Blue grama Bouteloua gracilis
Hairy grama Bouteloua hirsuta
Texas grama Bouteloua rigidiseta
Red grama Bouteloua trifida
Erect brachyelytrum Brachyelytrum erectum
Downy brome Bromus pubescens
Buffalograss Buchloe dactyloides
Broadleaf woodoats (Inland sea-oats) Chasmanthium latifolium
Hooded windmillgrass (Crowfoot grass) Chloris cucullata
Short-spike windmillgrass Chloris subdolichostachya
Tumble windmillgrass Chloris verticillata
Feather finger grass (Showy chloris) Chloris virgata
Carolina jointtail Coelorachis cylindrica
Fall witchgrass Digitaria cognata
American barnyard grass Echinochloa muricata
Canada wildrye Elymus canadensis
Virginia wildrye Elymus virginicus
Gummy lovegrass Eragrostis curtipedicellata
Big-top lovegrass Eragrostis hirsuta
Plains lovegrass Eragrostis intermidia
Spreading lovegrass Eragrostis pectinata
Creeping lovegrass Eragrostis reptans
Poverty droopseed Sporobolus vaginiflorus
White tridens Tridens albescens
Purpletop (redtop, purpletop tridens) Tridens flavus
Longspike tridens Tridens strictus
Eastern gammagrass Tripsacum dactyloides
Prairie trisetum Trisetum interruptum
Browntop signalgrass (Hurrah grass) Urochloa fasciculata
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Table E-3: Native Plants List – Grasses
Common Name Botanical Name
Broadleaf signalgrass Urochloa platyphylla
Texas panicum (Texas signalgrass) Urochloa texana
Common sixweeksgrass Vulpia octoflora
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Table E-4: Native Plants List – Herbaceous Wetland
Common Name Botanical Name
Ear-leaf ammannia Ammannia auriculata
Purple ammannia (Toothcup) Ammannia coccinea
Water-hyssop Bacopa monnieri
Disk water-hyssop Bacopa rotundifolia
Texas bergia (waterwort) Bergia texana
Caric sedge (Benjamin's sedge) Carex bushii
Davis' Caric sedge Carex davisii
Heavy-fruit caric sedge Carex gravida
Few-flower caric sedge Carex hyalina
Foxtail caric sedge Carex vulpinoidea
Taper-leaf flat sedge Cyperus acuminatus
Yellow flat sedge Cyperus flavescnes
Slender flat sedge Cyperus lupulinus
Fragrant flat sedge Cyperus odoratus
Bent-awn flat sedge Cyperus reflexus
One-flower flat sedge Cyperus retroflexus
Sedge Cyperus setigerus
Burhead (Erect burhead) Echinodorus berteroi
Creeping burhead Echinodorus cordifolius
Needle spikerush Eleocharis acicularis
Spikerush Eleocharis geniculata
Spikerush Eleocharis monteicensis
Large-spike spikerush Eleocharis palustris
Dwarf spikerush Eleocharis parvula
Square-stem spikerush Eleocharis quadrangulata
Horsetail (Scouring-rush) Equisetum hyemale
Fimbristylis Fimbristylis puberula
Umbrella sedge Fuirena simplex
Bladderpod (Bagpod) Glottidium vesicarium
Blue mud plantain Heteranthera limosa
Water-pennywort Hydrocotyle umbellata
Dudley's rush Juncus dudleyi
Common rush (Soft rush) Juncus effusus
Ring-seed rush Juncus filipendulus
Inland rush Juncus interior
Grassleaf rush Juncus marginatus
Torrey's rush Juncus torreyi
Water willow Justicia americana
Slender-leaf flat sedge Kyllinga pumila
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Table E-4: Native Plants List – Herbaceous Wetland
Common Name Botanical Name
Frogfruit (Lance-leaf frogfruit) Lippia lanceolata
Frogfruit (Turkey tangle) Lippia nodiflora
Seedbox (Rattlebox) Ludwigia alternifolia
Primrose-willow Ludwigia decurrens
Creeping seedbox (Torrey's seedbox) Ludwigia glandulosa
Water primrose Ludwigia prploides
Floating water primrose (Creeping primrose) Ludwigia repens
Water horehound (American bugleweed) Lycopus americanus
Lance-leaf loosestrife Lythrum alatum
California loosestrife Lythrum californicum
Prostrate water-hyssop Mecardonia procumbens
Lax hornpod Mitreola petiolata
Water pepper (Swamp smartweed) Polygonum hydropiperoides
Pink smartweed Polygonum pensylvanicum
Water smartweed Polygonum punctatum
Pleat-leaf knotweed Polygonum tenue
Pickerelweed Pontederia cordata
Star-rush white-top sedge (Umbrella grass) Rhynchospora colorata
Toothcup Rotala remosior
Common arrowhead (Duck potato, Wapato) Sagittaria latifolia
Delta arrowhead Sagittaria platyphylla
Lizard's tail Saururus cernuus
Giant bulrush Schoenoplectus californicus
Three-square bulrush (American bulrush) Schoenoplectus pungens
Soft-stem bulrush (Great bulrush) Schoenoplectus tabernaemontani
Rattlebush Sesbania drummondii
Southern cattail Typha domingensis
Common cattail Typha latifolia
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Table E-5: Native Plants List – Aquatic Plants
Common Name Botanical Name
Larger waterwort Callitriche heterophylla
Coontail Ceratophyllum demersum
Water stargrass Heteranthera dubia
Umbrella water-pennywort Hydrocotyle umbellata
Lesser duckweed Lemna aequinoctialis
Southern naiad Najas guadalupensis
Lotus Nelumbo lutea
Spatterdock (Cow lily, Yellow pond lily) Nuphar advena
White water-lily Nymphaea odorata
Water-thread pondweed Potamogeton diversifolia
Long-leaf pondweed Potamogeton nodosus
Baby pondweed Potamogeton pusillus
Sago pondweed Stuckenia pectinatus
Cone-spur bladderwort Utricularia gibba
Wild celery (Eel grass) Vallisneria americana
Common poolmat (horned pondweed) Zannichelia palustrus
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Table E-6: Native Plants List – Ferns
Common Name Botanical Name
Engelmann's Adder's tongue Ophioglossum engelmannii
Adder's tongue Ophioglossum vulgatum
Purple cliff-brake Pellaea atropurpurea
Common woodsia Woodsia obtusa
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Table E-7: Native Plants List – Cacti
Common Name Botanical Name
Pinapple cactus Coryphantha sulcata
Pincushion cactus Coryphantha vivipara
Plains nipple cactus Escobaria missouriensis
Eastern prickly-pear Opuntia humifusa
Plains prickly-pear Opuntia macrorhiza
Brown-spine prickly-pear Opuntia phaeacantha var. major
Green-flower cholla (Jumping cactus) Opuntia tunicata
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Table E-8: Native Plants List – Forbs (Wildflowers)
Common Name Botanical Name
Prairie acacia Acacia angustissima
Hop hornbeam Acalypha ostryifolia
Virginia copperleaf Acalypha virginica
Western yarrow Achillea millefolium
Wild onion (Meadow garlic) Allium canadense
Prairie onion Allium drummondii
Blue star (Texas slimpod) Amsonia ciliata
Ble star (Willow slimpod) Amsonia tabernaemontana
Blue funnel lily Androstephium coeruleum
Tenpetal anemone Anemone berlandieri
Carolina anemone Anemone caroliniana
Western rock-jasmine Anrdosac occidentalis
Pussytoes anemone Antennaria parlinii
Arkansas lazy daisy Aphanostpehus skirrhobasis
Prairie dogbane (Indian-hemp) Apocynum cannabinum
Green-dragon (Jack-in-the-pulpit) Arisaema dracontium
Indian plantain Arnoglossum plantagineum (Cacalia plantaginea)
Antelope-horns (trailing milkweed) Asclepias asperula
Butterfly milkweed Asclepias tuberosa
Green-flower milkweed Asclepias viridiflora
Green milkweed Asclepias viridis
Drummond's aster Aster drummondii
Heath aster Aster ericoides
Aromatic aster Aster oblongifolius
Late purple aster Aster patens var. gracilis
Silky aster Aster pratensis
Saltmarsh aster Aster subulatus
Bent-pod milk-vetch Astragalus distortus
Slim-pod milk-vetch Astragalus leptocarpus
Lotus milk-vetch Astragalus lotiflorus
Western daisy Astranthium intefrifolium
Plains wild indigo Baptisia bracteata
Green wild indigo Baptisia sphaerocarpa
Texas green-eyes Berlandiera betonicifolia (B. texana)
Prairie Bishop's weed Biflora americana
Scarlet spiderling Boerhavia diffusa
Erect spiderling Boerhavia erecta
Plains kuhnia (False boneset) Brickellia eupatorioides var. corymbulosa
Plains winecup (Plains poppy-mallow) Callirhoe alcaeoides
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Table E-8: Native Plants List – Forbs (Wildflowers)
Common Name Botanical Name
Winecup (Purple poppy-mallow) Callirhoe involucrata
Palmleaf poppy-mallow (Finger poppy-
mallow) Callirhoe pedata (C. digitata)
Sundrops (Squarebud day primrose) Calylophus berlandieri
Yellow sundrops (yellow eveving-primrose) Calylophus serrulatus
Horseherb (Prostrate lawnflower) Calyptocarpus vialis
Wild hyacinth Camassia scilloides
Indian paintbrush Castilleja indivisa
Redroot (Jersey tea) Ceanothus herbaceus
Basketflower Centaurea americana
Mountain pink Centaurium beyrichii
Lady Bird's centaury Centaurium texense
Short-stalked chickweed Cerastium brachypodum
Nodding chickweed Cerastium nutans
Wild cherry Chaerophyllum tainturieri
Common least daily Chaetopappa asteroides
Partridge pea Chameachrista fasciculata (Cassia fasciculata)
Sensitive pea Chameachrista nicitans (Cassia nictitans)
Pit-seed goosefoot Chenopodium berlandieri
Thick-leaf goosefoot Chenopodium pratericola
Soft golden aster (Camphorweed) Chrysopsis pilosa
Tall thistle Cirsium altissimum
Bull thistle Cirsium horridulum
Texas thistle Cirsium texanum
Violet collinsia Collinsia voilacea
Erect dayflower Commelina erecta
Texas bindweed Convolvulus equitans
Horseweed Conyza canadensis
Rain-lily Cooperia drummondii
Lance Coreopsis Coreopsis lanceolata
Plains coreopsis Coreopsis tinctoria
Rock coreopsis Coreopsis wrightii
Mealy fumewort Corydalis crystallina
Scratch daisy Croptilon hookerianum
Woolly croton Croton capitatus
Tropic croton Croton glandulosus
One-seeded croton Croton monanthogynous
Texas croton Croton texensis
Buffalo gourd Cucubita foetidissima
Texas Gourd Cucurbita texana
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Table E-8: Native Plants List – Forbs (Wildflowers)
Common Name Botanical Name
Winged pigweed Cycloloma atriplicifolium
Showy prairie clover Dalae compacta
Golden dalea Dalea aurea
White prairie clover Dalea candida var candida
Bigtop dalea Dalea enneandra
Round-head dalea (White prairie clover) Dalea multiflora
Angels Trumpet (Indian apple) Datura wrightii
Rattlesnake-weed Daucus pusillus
Prairie larkspur Delphinium carolinianum var. virescens
Tansy mustard Descurainia pinnata
Illinois bundleflower Desmanthus illinoensis
Prairie bundleflower Desmanthus leptolobus
Panicled tick-clover Desmodium paniculatum
Sessile tick-clover Desmodium sessilifolium
Tweedy's tick-clover Desmodium tweedyi
Pony foot Dichondra carolinensis
Woolly cotton-flower Dimorphocarpa wislizenii
Rough buttonweed Diodia teres
Low silverbush (Low wild mercury) Ditaxis humilis
Shooting star Dodecatheon meadia
Wedge-leaf draba (Whitlow-wort) Draba cuneifolia
Broad-pod draba Draba platycarpa
Carolina draba Draba reptans
Clasping coneflower Dracopis amplexicaulis
Snake Herb Dyschoriste linearis
Blacksamson Echinacea angustifolia
Purple coneflower Echinacea atrorubens
Yarva de tajo (Pieplant) Eclipta prostrata
Englemann daisy Englemannia peristenia (E. pinnatifida)
Basin fleabane Erigeron geiseri
Philadelphia fleabane Erigeron philadelphicus
Annual wild buckwheat Eriogonum annuum
Longleaf wild buckwheat Eriogonum longifolium
Heart-sepal wild buckwheat Eriogonum multiflorum
Prairie fleabane Eriogonum strigosus
Texas stork's bill Erodium texanum
Brushy eryngo Eryngium diffusum
Hooker's enyngo Eryngium hookeri
Leavenworth eryngo Eryngium leavenworthii
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Table E-8: Native Plants List – Forbs (Wildflowers)
Common Name Botanical Name
Rattlesnake master (Button snakeroot) Eryngium yuccifolium
Western wallflower Erysimum capitatum
Tall thoroughwort Eupatorium altissimum
Blue mist flower Eupatorium coelestinum
Late-flowering boneset Eupatorium serotinum
Snow-on-the-prairie Euphorbia bicolor
Fire-on-the-mountain Euphorbia cyanthophora
Tootherd spurge Euphorbia dentata
Snow-on-the-mountain Euphorbia marginata
Weak spurge Euphorbia tetrapoda
Texas spreadwing Eurytaenia texana
Bluebells Eustoma russellianum (E. grandiflorum)
Big-head pygmycudweed Evax prolifera
Spring pygmycudweed Evax verna
Shaggy dwarf morning-glory Evolvulus nuttallianus
Silver dwarf morning-glory Evolvulus sericeus
Florida snake cotton Froelichia floridana
Prairie gaillardia (Lanceleaf gaillardia) Gaillardia aestivalis
Indian blanket Gaillardia pulchella
Fragrant gaillardia Gaillardia sauvis
Woods bedstraw (Wild licorice) Galium circaezans
Hairy bedstraw Galium pilosum
Plains gaura Gaura brachycarpa
Sweet gaura (Beeblossom) Gaura drummondii
Velvetweed (Lizard-tail gaura) Gaura parviflora
Wavy-leaf gaura (Wavyleaf beeblossom) Gaura sinuata
Wild honeysuckle Gaura suffulta
Crane's bill (Carolina geranium) Geranium carolinianum
White avens Geum canadense
Dakota vervain Glandularia bipinnatifida (Verbena bipinnatifida)
Rose vervain Glandularia canadensis (Verbena canadensis)
Bladderpod (Bagpod) Glottidium vesicarium
Lonestar gumweed (Little-head gumweed) Grindelia adenodonta
Narrow-leaf gumweed Grindelia lanceolata
Prairie bluets Hedyotis nigricans
Common sunflower Helianthus annuus
Texas blueweed (Blue-weed sunflower) Helianthus cilaris
Maximilian Sunflower Helianthus maximiliani
India heliotrope (turnsole) Heliotropium indicum
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Table E-8: Native Plants List – Forbs (Wildflowers)
Common Name Botanical Name
Pasture heliotrope Heliotropium tenellum
Bladdermallow (Net-Vein herissantia) Herissantia crispa
Gray golden-aster Heterotheca canescens
Camphorweed Heterotheca subaxillaris
Hawkweed Hieracium gronovii
Nodding green violet Hybanthus verticillatus
Carolina wooly-white (Old-plainsman) Hymenopappus acabiosaeus
Old-plainsman (Woolly-white) Hymenopappus artemisifolius
Spotted St. John's wort Hypericum punctatum
Scarlet pea Indigofera miniata
Standing cypress Ipomopsis rubra
Sumpweed (Marsh-elder) Iva annua
Warty calrop Kallstroemia parviflora
Trailing ratany Krameria lanceolata
Virginia dwarfdandelion Krigia virginica
Wright's dwarfdandelion Krigia wrightii
Wild lettuce Lactuca canadensis
Western wild lettuce Lactuca ludoviciana
Narrow-leaf pinweed Lechea tenuifolia
Virginia pepperweed Lepidium virginicum
Hairy bush-clover Lespedeza hirta
Trailing bush-clover Lespedeza procumbens
Tall bush-clover Lespedeza stuevei
Slender lepedeza Lespedeza virginicum
White bladderpod Lesquerella gracilis
Narrow-leaf conobea Leucospora multifida
Tall gayfeather (Tall blazing star) Liatris aspera
Pink-scale gayfeather (Handsome blazing
star) Liatris elegans
Narrow-leaf gayfeather Liatris mucronata
Prairie blazing star (Kansas gayfeather) Liatris pynchostachya
Smooth gayfeather (Scaly blazing star) Liatris squarrosa var. glabrata
Arkansas dogshade Limnosciadium pinnatum
False pimpernel Lindernia dubia
Texas yellow star Lindheimera taxana
Small meadow flax Linum pratense
Stiffstem flax Linum rigidum
Puccoon (Carolina gromwell) Lithospermum caroliniense
Narrowleaf gromwell (Narrowleaf puccoon) Lithospermum incisum
Cardinal flower Lobelia cardinalis
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Table E-8: Native Plants List – Forbs (Wildflowers)
Common Name Botanical Name
Carrot-leaf lomatium Lomatium foeniculaceum
Deervetch (Prairie trefoil) Lotus purshianus (L. unifoliolatus)
Texas bluebonnet Lupinus texensis
Texas skeleton plant Lygodesmia texana
Turks Cap (Wax mallow) Malvaviscus arboreus v. drummondii
Barbara's buttons (Puffballs) Marshallia caespitosa
Creeping cucumber Melothria pendula
Stickleaf (Chickenthief) Mentzelia oilgosperma
White four-o'clock Mirabilis albida
Giant four-o'clock Mirabilis gigantea
Narrow-leaf four-o'clock Mirabilis linearis
Wild four-o'clock Mirabilis nyctaginea
Carolina bristlemallow Modiola caroliniana
Lemon mint (Lemon beebalm) Monarda citriodora
Basil beebalm Monarda clinopodioides
Wild bergamont Monarda fistulosa
Spotted beebalm Monarda punctata
Poverty-weed Monolepis nuttalliana
Spring forget-me-not Myosotis macrosperma
Southern forget-me-not Myosotis verna
tiny mousetail Myosurus minimus
Prairie celestial Nemastylis geminiflora
Yellow puff Neptunia lutea
Crow poison (False garlic) Nothoscordum bivalve
Texas toad-flax Nuttallanthus texanus
Scarlet muskflower Nyctaginia capitata
Cutleaf evening primrose Oenothera laciniata
Four-point evening primrose Oenothera rhombipetala
Spack evening primrose Oenothera spachiana
Showy evening primrose Oenothera speciosa
Stemless evening primrose Oenothera triloba
Soft-hair marbleseed Onosmodium bejariense
Aniseroot Osmorhiza longistylis
Common yellow oxalis Oxalis stricta
Violet woodsorrel Oxalis vioacea
Prairie groundsel Packera plattensis (Senecio plattensis)
Small palafoxia Palafoxia callosa
Rose palafoxia Palafoxia rosea
Passionflower Passiflora incarnata
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Table E-8: Native Plants List – Forbs (Wildflowers)
Common Name Botanical Name
Tall-bread scurf-pea Pediomelum cuspidata (Psoralea cuspidata)
Rock scurf-pea Pediomelum reverchonii (Psoralea reverchonii)
Round-leaf scurf-pea Pediomelum rhombifolium
Foxglove Penstemon cobaea
Beardtongue Penstemon laxiflorus
Blue curls Phacelia congesta
Annual phlox (Pride-of-Texas) Phlox drummondii var. mcallisterii
Prairie Phlox Phlox pilosa
Drummond's leaf-flower Phyllanthus abnormis
Knotweed leaf-slower Phyllanthus polygonoides
Cut-leaf ground-cherry Physalis angulata
Beach ground-cherry Physalis cinerascens
Downy groundcherry (Husk tomato) Physalis pubescens
Finger flase dragonhead Physostegia digitalis
Beautiful false dragonhead Physostegia pulchella
Obedient Plant Physostegia virginiana var. praemorse
Pokeweed Phytolacca americana
Bracted plantain (Bottlebrush plantain) Plantago aristata
Prairie plantain (Slender plantain) Plantago elongata
Slender plantago (Slim-spike plantago) Plantago heterophylla
Bristle-bracted plantain Plantago patagonica
Red-seed plantain (Tallow-weed) Plantago rhodosperma
Pale-seed plantain Plantago virginica
Purple pluchea (Marsh fleabane) Pluchea odorata
Clammyweed Polansia dodecandra
White milkwort Polygala alba
Pink milkwort (Procession flower) Polygala incarnata
Pleat-leaf knotweed Polygonum tenue
Juniper-leaf Polypremum procumbens
Prairie parsley Polytaenia nuttallii
Common selfheaf (Heal-all) Prunella vulgaris var. lanceolata
Edible scurf-pea Psoralea hypogaeum var. subulatum
Wild alfalfa (Slim-leaf scurf-pea) Psoralea tenuiflora
Mock bishop's weed Ptilimnium nuttallii
False dandelion (Carolina desert-chickory) Pyrrhopappus carolinianus
Texas dandelion (Smallflower desert-
chickory) Pyrrhopappus pauciflorus
Mexican hat (Upright prairie coneflower) Ratibida columnifera
Pigeonberry (Rougeplant) Rivina humilis
Blackeyed Susan Rudbeckia hirta
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Table E-8: Native Plants List – Forbs (Wildflowers)
Common Name Botanical Name
Low ruellia Ruellia humilis
Pale dock Rumex altissimus
Heart-wing sorrel Rumex hastatulus
Meadow pink Sabatia campestris
Buckley's sabatia Sabatia formosa
Trailing pearlwort Sagina decumbens
Blue sage Salvia azurea
Tropical sage Salvia coccinea
Engelmann's sage Salvia engelmannii
Mealycup sage Salvia farinacea
Texas sage Salvia texana
Thin-leaf brookweed Samolus valerandi
Black snakeroot Sanicula canadensis
Catclaw sensitive briar Schrankia nuttallii (Mimosa nutallii)
Roemer sensitive briar Schrankia roemeriana (Mimosa roemeriana)
Small scullcap Scutellaria parvula
Wright's skullcap Scutellaria wrightii
Yellow stonecrop Sedum nuttallianum
Texas groundsel Senecio ampullaceus
Cofee-bean Sesbania herbacea (S. macrocarpa)
Rock cress Sibara virginica
Bur cucumber Sicyos angulatus
Spreading fanpetal Sida abutifolia
Prickly fanpetals Sida spinosa
Sleepy catchfly Silene antirrhina
Widow's frill Silene stellata
Compassplant Silphium laciniatum
Sword-leaf blue-eyed grass Sisyrinchium chilense
Dotted blue-eyed grass Sisyrinchium pruinosum (S. langloisii)
American nightshade Solanum ptychenthum (Solanum americanum)
Common goldenrod Solidago canadensis
Tall goldenrod Solidago gigantea
Stiff goldenrod Solidago rigida
Elm-leaf goldenrod Solidago ulmifolia
Forked scaleseed Spermolepis divaricata
beggar's-lice (Bristly scaleseed) Spermolepis echinata
Spreading scaleseed Spermolepis inermis
Slender ladies' tresses Spiranthes lacera
Mousesear Stachys crenata
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Table E-8: Native Plants List – Forbs (Wildflowers)
Common Name Botanical Name
False gaura Stenosiphon linifolius
Smooth jewelflower (Smooth twistflower) Streptanthus hyacinthoides
Trailing wild bean Strophostyles helvola
Smooth-seed wild bean Strophostyles leiosperma
Sunbright (Prairie flameflower) Talinum parviflorum
Goat's rue (Virginia tephrosia) Tephrosia virginiana
Sawtooth nerveray Tetragonotheca ludoviciana
Fineleaf four-nerve daisy Tetraneuris linearifolia (Hymenoxys linearifolia)
Wood sage Teucrium canadense
Greenthread Thelesperma filifolium
Small Bristle-leaf (Tiny Tim) Thymophylla tenuiloba
Ohis spiderwort Tradescantia ohioensis
Tharp's spiderwort Tradescantia tharpii
Peanut clover Trifolium polymorphum
Venus' looking glass Triodanis holzingeri
Slender-leaved Venus looking-glass Triodanis leptocarpa
Hen and Chickens Triodanis perfoliata
Beaked cornsalad Valerianella radiata
Wood's cornsalad Valerianella woodsiana
Bracted vervain Verbana bractaeta
Texas vervain Verbena halei
Hoary vervain Verbena stricta
White vervain Verbena urticifolia
Gulf vervain (Course vervain) Verbena xutha
Cowpen daisy (Golden crownbeard) Verbesina encelioides
White Crownbeard (Frostweed, Iceplant) Verbesina virginica
Western ironweed Vernonia baldwinii
Purslane speedwell (Neckweed) Veronica peregrina
Blue violet Viola palmata
Common blue violet Viola sororia
Carolina violet Viola villosa
Prairie brazoria Warnockia scutellarioides
Orange zexmenia Wedelia texana (Zexmenia hispida)
Texas sleepy daisy Xanthisma texanum
Design Criteria Manual
Published: January 2026
Design Criteria Manuals i
Published: January 2026
Table of Contents
Section 1: Introduction........................................................................................... 1
1.1 Title and Effective Date ....................................................................................................... 1
1.2 Purpose ................................................................................................................................. 1
1.3 Organization ......................................................................................................................... 1
Section 2: Abbreviations and Definitions ............................................................ 2
2.1 Abbreviations ....................................................................................................................... 2
2.2 Definitions ............................................................................................................................. 6
Section 3: Solid Waste Design Criteria ............................................................... 20
3.1 Overview ............................................................................................................................. 20
3.2 Design Standards ............................................................................................................... 20
3.2.1 General ............................................................................................................................................................................................ 20
3.2.2 Container Enclosure and Storage Space Dimensional Requirements .................................................................. 21
3.2.3 Container Enclosure Design Requirements...................................................................................................................... 23
3.2.4 Enclosure Access, Placement, Ingress, and Egress Requirements .......................................................................... 23
3.2.5 Alleyway Access ........................................................................................................................................................................... 25
Section 4: Stormwater Design Criteria ............................................................... 27
4.1 Overview ............................................................................................................................. 27
4.1.0 Organization ................................................................................................................................................................................. 27
4.2 Design Focus ....................................................................................................................... 28
4.3 Design Storms.................................................................................................................... 28
4.4 Hydrologic Methods .......................................................................................................... 29
4.4.1 Types of Hydrologic Methods ............................................................................................................................................... 29
4.4.2 Rainfall Estimation ...................................................................................................................................................................... 30
4.5 Acceptable Downstream Conditions for Open Channels and Floodplains ................... 30
4.5.1 Downstream Assessments ....................................................................................................................................................... 30
4.5.2 Adverse Impacts .......................................................................................................................................................................... 31
4.5.3 Stormwater Diversions .............................................................................................................................................................. 32
4.5.4 Streambank Protection ............................................................................................................................................................. 32
4.5.5 Flood Mitigation .......................................................................................................................................................................... 33
4.6 Stormwater System Design ............................................................................................... 34
4.6.1 Introduction ................................................................................................................................................................................... 34
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits ...................................................................................... 34
4.6.3 Open Channels ............................................................................................................................................................................. 49
4.7 Culverts................................................................................................................................ 53
4.7.1 Design Frequency ....................................................................................................................................................................... 53
4.7.2 Design Criteria .............................................................................................................................................................................. 53
4.7.3 Driveway Culverts........................................................................................................................................................................ 54
4.8 Bridges................................................................................................................................. 55
4.8.1 Design Frequency ....................................................................................................................................................................... 55
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4.8.2 Design Criteria .............................................................................................................................................................................. 55
4.8.3 Other Criteria ................................................................................................................................................................................ 56
4.9 Detention Facilities ............................................................................................................ 56
4.9.1 Design Requirements ................................................................................................................................................................ 56
4.9.2 Design Criteria for Above Grade Detention Facilities .................................................................................................. 56
4.9.3 Design Criteria for Underground Detention Facilities ................................................................................................. 58
4.9.4 Design Criteria for Parking Lot Detention ........................................................................................................................ 59
4.9.5 Design Criteria for Pumped Detention .............................................................................................................................. 60
4.9.6 Outlet Structures for Detention Facilities ......................................................................................................................... 60
4.10 Energy Dissipation ............................................................................................................. 63
4.10.1 Design Frequency ....................................................................................................................................................................... 63
4.10.2 Design Criteria .............................................................................................................................................................................. 63
4.10.3 Recommended Energy Dissipater for outlet protection............................................................................................. 63
4.11 Floodplain ........................................................................................................................... 63
4.11.1 Floodplain Development Criteria ......................................................................................................................................... 63
4.11.2 Procedures for Floodplain Alteration ................................................................................................................................. 67
4.11.3 Fully Developed Water Surface Elevation Calculations ............................................................................................... 68
4.11.4 Floodplain Alteration Guidelines .......................................................................................................................................... 68
4.12 Drainage and Floodplain Easements ................................................................................ 69
4.12.1 General ............................................................................................................................................................................................ 69
4.12.2 Storm Drain Easements ............................................................................................................................................................ 69
4.12.3 Channel Access ............................................................................................................................................................................ 70
4.12.4 Detention Facilities Easements .............................................................................................................................................. 71
4.12.5 Post-Construction Water Quality Control Structure Easements ............................................................................. 71
4.12.6 Fences .............................................................................................................................................................................................. 71
4.13 Water Quality...................................................................................................................... 71
4.13.1 Water Quality Protection Volume ........................................................................................................................................ 71
4.13.2 Water Quality Hotspots ............................................................................................................................................................ 72
4.13.3 Required Stormwater Facility Maintenance Agreements ........................................................................................... 72
4.13.4 Construction Erosion and Sediment Control Requirements ..................................................................................... 73
4.14 Stormwater Facility Maintenance Agreements .............................................................. 79
4.14.1 Maintenance Agreements ....................................................................................................................................................... 79
4.14.2 Private Maintenance (SWFMA Required) .......................................................................................................................... 79
4.14.3 Maintenance Agreement Requirements ........................................................................................................................... 80
Section 5: Transportation Design Criteria ......................................................... 82
5.1 Overview ............................................................................................................................. 82
5.1.1 Organization ................................................................................................................................................................................. 82
5.2 Mobility Framework ........................................................................................................... 83
5.2.1 Roadway Functional Classifications ..................................................................................................................................... 83
5.2.2 Auxiliary Roadway Classifications ......................................................................................................................................... 85
5.3 Roadway Design ................................................................................................................. 86
5.3.1 Design Controls ........................................................................................................................................................................... 86
5.3.2 Street Sections.............................................................................................................................................................................. 86
5.4 Intersection Design ............................................................................................................ 88
5.4.1 Geometry ........................................................................................................................................................................................ 88
5.4.2 Visibility Standards ..................................................................................................................................................................... 89
5.4.3 Vertical Curve Standards .......................................................................................................................................................... 90
5.4.4 Turn Lane Requirements .......................................................................................................................................................... 90
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5.4.5 Intersection Detail for Collectors and Arterials .............................................................................................................. 93
5.4.6 Intersection Spacing .................................................................................................................................................................. 94
5.4.7 Roundabouts ................................................................................................................................................................................ 94
5.5 Auxiliary Roadway Design ................................................................................................. 95
5.5.1 Alleys ................................................................................................................................................................................................ 95
5.5.2 Drives ............................................................................................................................................................................................... 95
5.5.3 Cul-de-sacs .................................................................................................................................................................................. 104
5.5.4 Hammerhead Turnarounds ................................................................................................................................................... 105
5.5.5 Supplementary Design Elements ....................................................................................................................................... 106
5.6 Access Management ........................................................................................................ 111
5.6.1 Purpose and Goals.................................................................................................................................................................... 111
5.6.2 Access Standards....................................................................................................................................................................... 111
5.6.3 Fire Apparatus Access Roads ............................................................................................................................................... 113
5.7 Bike and Pedestrian Facility Design ............................................................................... 114
5.7.1 Mobility Plan Component ..................................................................................................................................................... 114
5.7.2 Accessibility Standards ........................................................................................................................................................... 114
5.7.3 Geometric Standards ............................................................................................................................................................... 115
5.7.4 Intersection .................................................................................................................................................................................. 116
5.7.5 Signage and Pavement Markings ...................................................................................................................................... 116
5.7.6 Amenities ...................................................................................................................................................................................... 116
5.8 Transit Facility Design ...................................................................................................... 118
5.8.1 General .......................................................................................................................................................................................... 118
5.8.2 Bus Stop Placement ................................................................................................................................................................. 119
5.8.3 Bus Stop Amenities .................................................................................................................................................................. 119
5.8.4 Bus Stop Signage and Markings ......................................................................................................................................... 120
5.9 Traffic Impact Analysis Guidelines ................................................................................. 120
5.9.1 General .......................................................................................................................................................................................... 120
5.9.2 Trip Generation Assessment ................................................................................................................................................. 120
5.9.3 When is a TIA required? ......................................................................................................................................................... 121
5.9.4 TIA Category and Study Area ............................................................................................................................................... 121
5.9.5 TIA Scoping and Report ......................................................................................................................................................... 122
5.9.6 School Traffic Management Plan ....................................................................................................................................... 123
5.9.7 Safety Assessment .................................................................................................................................................................... 124
5.9.8 Queue Analysis for Drive Through Facilities .................................................................................................................. 125
5.9.9 TIA Submission and Review Procedures ......................................................................................................................... 125
5.10 Pavement Design Standard ............................................................................................. 125
5.10.1 Streets ............................................................................................................................................................................................ 125
5.10.2 Drive Approach .......................................................................................................................................................................... 126
5.11 Complete and Context-Sensitive Streets ....................................................................... 126
Section 6: Water and Wastewater Design Criteria ......................................... 128
6.1 Overview ........................................................................................................................... 128
6.1.1 Organization ............................................................................................................................................................................... 128
6.2 Water Design Criteria ...................................................................................................... 129
6.2.1 Distribution System Extensions ........................................................................................................................................... 129
6.2.2 Water Main Horizontal and Vertical Alignment ........................................................................................................... 133
6.2.3 Depth of Cover for Water Mains ........................................................................................................................................ 133
6.2.4 Pipe and Fittings ........................................................................................................................................................................ 133
6.2.5 Connections................................................................................................................................................................................. 136
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6.2.6 Valves ............................................................................................................................................................................................. 136
6.2.7 Dead-End Mains ........................................................................................................................................................................ 138
6.2.8 Fire Hydrant Locations and Coverage .............................................................................................................................. 139
6.2.9 Meters and Meters Cans/Vaults ......................................................................................................................................... 139
6.2.10 Underground Utility Crossing .............................................................................................................................................. 146
6.2.11 Fence or Wall Crossings ......................................................................................................................................................... 147
6.2.12 Non-City Road Crossings ...................................................................................................................................................... 148
6.2.13 Railroad Crossings .................................................................................................................................................................... 148
6.2.14 Creek Crossings ......................................................................................................................................................................... 148
6.2.15 Elevated Crossings .................................................................................................................................................................... 148
6.2.16 Tunneling, Boring, Jacking and Casing ............................................................................................................................ 149
6.2.17 Existing Water Main Replacement ..................................................................................................................................... 149
6.2.18 Requirements for Abandoning Water Mains ................................................................................................................ 150
6.2.19 Water Treatment Plants, Ground Storage Tanks, ESTs, Pressure Tanks, and Booster Pump Stations .. 150
6.3 Wastewater Design Criteria ............................................................................................. 150
6.3.1 Estimated Wastewater Flows................................................................................................................................................ 150
6.3.2 Size and Slope of Sewers ....................................................................................................................................................... 152
6.3.3 Sewer Alignment ....................................................................................................................................................................... 153
6.3.4 Sewer Main Depth and Recommended Cover ............................................................................................................. 153
6.3.5 Gravity and Force Main Sewer Pipe Material ................................................................................................................ 154
6.3.6 Sewer Pipe Embedment ......................................................................................................................................................... 154
6.3.7 Manholes ...................................................................................................................................................................................... 154
6.3.8 Sewer Laterals ............................................................................................................................................................................. 155
6.3.9 Underground Utility Crossings ............................................................................................................................................ 156
6.3.10 Fence or Wall Crossings ......................................................................................................................................................... 156
6.3.11 Non-City Road Crossings ...................................................................................................................................................... 156
6.3.12 Railroad Crossings .................................................................................................................................................................... 156
6.3.13 Creek Crossings ......................................................................................................................................................................... 157
6.3.14 Tunneling, Borings, Jacking, and Casing ......................................................................................................................... 157
6.3.15 Abandonment of Sewer Mains ............................................................................................................................................ 157
6.3.16 Abandonment of Manholes.................................................................................................................................................. 158
6.3.17 Lift Stations .................................................................................................................................................................................. 158
6.3.18 Low-Pressure or Alternative Collection Systems ......................................................................................................... 164
6.3.19 Wastewater Treatment Plants, And Peak Flow Detention Facilities ..................................................................... 164
6.3.20 On-Site Sewage Facilities ....................................................................................................................................................... 164
6.3.21 Pretreatment Device: Grease Interceptors / Grit Traps / Oil Separators ............................................................ 165
6.3.22 Inspections Required ............................................................................................................................................................... 170
6.4 Construction Plans ........................................................................................................... 170
6.4.1 General .......................................................................................................................................................................................... 170
6.4.2 Responsibility .............................................................................................................................................................................. 170
6.4.3 Format............................................................................................................................................................................................ 170
6.4.4 Plan Requirements.................................................................................................................................................................... 170
Section 7: Streetlight Design Criteria ............................................................... 172
7.1 Overview ........................................................................................................................... 172
7.1.1 Applicability ................................................................................................................................................................................. 172
7.1.2 Organization ............................................................................................................................................................................... 172
7.2 Requirements .................................................................................................................... 173
7.2.1 General .......................................................................................................................................................................................... 173
7.2.2 Roadway Lighting Requirements ....................................................................................................................................... 173
7.2.3 Installation Requirements ...................................................................................................................................................... 178
7.2.4 Construction Requirements .................................................................................................................................................. 184
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7.3 Developer and DME Responsibilities ............................................................................. 184
7.3.1 Highways and Streets (except local residential streets with speed ≤ 30 mph) .............................................. 184
7.3.2 Local Residential Streets (with speed limits ≤ 30mph) ............................................................................................. 185
7.3.3 Streetlighting in Non-DME-Served Areas ...................................................................................................................... 186
7.3.4 Customer/Citizen Requests for addition/removal of Streetlighting .................................................................... 186
Section 8: Environmentally Sensitive Areas Design Criteria ......................... 187
8.1 Overview ........................................................................................................................... 187
8.2 ESA Identification ............................................................................................................. 187
8.2.1 The Official ESA Map ............................................................................................................................................................... 187
8.3 ESA Field Assessments ..................................................................................................... 188
8.3.1 ESA Field Assessor .................................................................................................................................................................... 188
8.3.2 ESA Forms .................................................................................................................................................................................... 188
8.3.3 ESA Field ....................................................................................................................................................................................... 188
8.4 ESA Preservation Requirements ..................................................................................... 189
8.4.1 ESA Inspections .......................................................................................................................................................................... 189
8.5 Restoration Plans for Permitted Uses and Activities .................................................... 191
8.5.1 Restoration Plan Requirements........................................................................................................................................... 191
8.5.2 Restoration Activities and Alternative ESA Plan Mitigation .................................................................................... 191
Section 9: Design Deviations ............................................................................. 192
9.1 Overview ........................................................................................................................... 192
9.1.1 General .......................................................................................................................................................................................... 192
9.2 Design Deviation Procedure ........................................................................................... 192
9.3 Revocation of an Approved Design Deviation .............................................................. 193
Appendix A: Example Stormwater Facility Checklists .................................... 194
Appendix B: Design Deviation Request Form ................................................. 200
Appendix C: Poles and Luminaires - Standard Lighting Fixtures ................. 204
Appendix D: Types of Environmentally Sensitive Areas ................................ 210
Appendix E: Native Plants for ESAs .................................................................. 212
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Section 1: Introduction
1.1 Title and Effective Date
1.1.1 This document is the Design Criteria Manual of the City of Denton, Texas. It shall be officially known
and cited as the “Denton Design Criteria Manual,” and is referred to internally in this document as “this
DCM” and “this Manual.”
1.1.2 This DCM shall become effective on January 1, 2026.
1.2 Purpose
The purpose of the Denton Design Criteria Manual is to provide minimum, non-exhaustive guidelines for
the design and construction of solid waste, stormwater, transportation, water and wastewater, and
streetlight infrastructure within the City of Denton, Texas and its extraterritorial jurisdictions. The criteria
established in this Manual have been developed from a review of various applicable publications, regulatory
requirements, and City of Denton offices which oversee the design, construction and maintenance of the
facilities.
These guidelines are to be used by design engineers in the City of Denton Capital Projects and Engineering
Department, consulting engineers employed by the City, and engineers of subdivision and land
development infrastructure projects proposed for construction and acceptance by the City, within the City
and its extraterritorial jurisdictions.
Along with this Manual, the Denton Development Code (DDC) and relevant submittal checklists should be
consulted for additional criteria. The criteria established in this Manual do not supersede the criteria
contained in the DDC. In the case of conflict among this Manual, City of Denton Standard Details, or other
cited regulations and standards, the more stringent requirement shall apply.
This DCM is not intended to be an all-inclusive design document for all circumstances and conditions. The
DDC and City of Denton Code of Ordinances must be consulted for possible impacts to the proposed
design. The Federal Government, the State of Texas, NCTCOG, Denton County, Denton County Transit
Authority (DCTA), and other related organizations and resources should be consulted for additional criteria,
as may be deemed necessary.
1.3 Organization
In addition to the design criteria established in this DCM, guidance is also provided for design deviations
from the required design criteria. The contents of this Manual are categorized into sections shown below:
A. Section 1: Introduction
B. Section 2: Abbreviations and Definitions
C. Section 3: Solid Waste Design
D. Section 4: Stormwater Design
E. Section 5: Transportation Design
F. Section 6: Water and Wastewater Design
G. Section 7: Streetlight Design Criteria
H. Section 8: Design Deviations
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Section 2: Abbreviations and Definitions
2.1 Abbreviations
AASHTO American Association of State Highway and Transportation Officials
ADA Americans with Disabilities Act
APBP Association of Pedestrian and Bicycle Professionals
ASTM American Society for Testing and Materials
AWSC All-Way Stop Control
AWWA American Water Works Association
BFE Base Flood Elevation
BFR Barrier Free Ramp
BOC Back of Curb
BMP Best Management Practices
CCN Certificate of Convenience and Necessity
cfs cubic feet per second
CLOMR Conditional Letter of Map Revision
COA Condominium Owner’s Association
CP Cathodic Protection
cu. ft. cubic feet
cu. in. cubic inches
DCAD Denton Central Appraisal District
DCM Design Criteria Manual
DCTA Denton County Transit Authority
DDC Denton Development Code
DFW Dallas-Fort Worth Metroplex
DIP Ductile-Iron Pipe
DRP Development Review Process
DSA Down Stream Assessment
EOL End-of-Line
ESA Environmentally Sensitive Area
ft. foot or feet
FEMA Federal Emergency Management Agency
FFE Finished Floor Elevation
Section 2: Abbreviations and Definitions
2.1 Abbreviations
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FHWA Federal Highway Administration
FIRM Federal Insurance Rate Map
FIS Flood Insurance Study
FM Farm to Market
fps feet per second
FSE Food Service Establishment
gal. gallon(s)
GPCD gallons per capita per day
GPD gallons per day
GPM gallons per minute
GPS Global Positioning System
HDPE High Density Polyethylene
HEC-HMS Hydrologic Engineering Center’s Hydrologic Modeling System
HEC-RAS Hydrologic Engineering Center's River Analysis System
HGI Hydromechanical Grease Interceptor
HGL Hydraulic Grade Line
HOA Home Owners’ Association
IBC International Building Code
ID Inner Diameter
IFC International Fire Code
IH Interstate Highway
in. inch(es)
IPC International Plumbing Code
ITE Institute of Transportation Engineers
iSWMTM Integrated Stormwater Management
kg. kilogram(s)
lb. pound or pounds
LOMR Letter of Map Revision
LOS Level-of-Service
MEP Mechanical, Electrical, and Plumbing
MGD Million Gallons per Day
mL milli-liter(s)
mph miles per hour
Section 2: Abbreviations and Definitions
2.1 Abbreviations
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NAVD North American Vertical Datum
NCHRP National Cooperative Highway Research Program Report
NCTCOG North Central Texas Council of Governments
NFIP National Flood Insurance Program
NFPA National Fire Protection Association
NGVD National Geodetic Vertical Datum
NOAA National Oceanic and Atmospheric Administration
PHT Peak-Hour Trips
PMF Probable Maximum Flood
PMP Probable Maximum Precipitation
POA Property Owners’ Association
POTW Publicly Owned Treatment Works
PROWAG Public Rights of Way Accessibility Guidelines
psi pounds per square inch
PUCT Public Utilities Commission of Texas
PUE Public Utility Easement
PVC Polyvinyl Chloride
PZC Planning and Zoning Commission
RCP Reinforced Concrete Pipe
ROW Right-of-Way
RPBA Reduced Pressure Backflow Assembly
SCADA Supervisory Control and Data Acquisition
SCS Soil Conservation Service
SDR Standard Dimension Ratio
SFE Single-Family Equivalent
SETP-PD Safety End Treatment Plan – Parallel Drainage
SFHA Special Flood Hazard Area
SH State Highway
sq. ft. square feet
sq. mi. square mile(s)
SWFMA Stormwater Facility Maintenance Agreement or Maintenance Agreement
TAC Texas Administrative Code
TAS Texas Accessibility Standards
Section 2: Abbreviations and Definitions
2.1 Abbreviations
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TCEQ Texas Commission on Environmental Quality
TDLR Texas Department of Licensing and Registration
TGA Trip Generation Assessment
TIA Traffic Impact Analysis
TMUTCD Texas Manual on Uniform Traffic Control Devices
TSS Total Suspended Solids
TxDOT Texas Department of Transportation
U.S. United States of America
USACE United States Army Corps of Engineers
USGS United States Geological Survey
VPD Vehicle-trips per day
WOTUS Waters of the United Stated of America
WMP Water Master Plan
WSEL Water Surface Elevation
w.s.f.u. Water-Supply Fixture-Unit(s)
ZOI Zone of Influence
Section 2: Abbreviations and Definitions
2.2 Definitions
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2.2 Definitions
20-Year Horizon
The estimated traffic volume for the study area based on a 20 -year growth period.
100-year Event
Event (rainfall or flood) that has a 1% chance of being equaled or exceeded in any given year.
Abutment
A wall supporting the end of a bridge or span and sustaining the pressure of the bordering earth.
Applicant
Any firm, entity, partnership, company, public utility company, or individual that submits a formal request
or application.
Apron
A floor or lining of concrete, timber, or other suitable material at the toe of a dam, entrance or discharge
side of a spillway, a chute, or other discharge structure, to protect the waterway from erosion from falling
water or turbulent flow.
Area of Special Flood Hazard
The area designated as subject to flooding from the 1% chance flood on the flood insurance rate map. For
purposes of these criteria, the term "special flood hazard area" is synonymous in meaning with the phrase
"area of special flood hazard" and may be ref erred to as "SFHA".
Backwater
The rise of the water level upstream due to an obstruction or constriction in the channel.
Backwater Curve
The term applied to the longitudinal profile of the water surface in an open channel when flow is steady but
non-uniform.
Baffles
Deflector vanes, guides, grids, gratings, or similar devices constructed or placed in flowing water, to: (1)
check or effect a more uniform distribution of velocities; (2) absorb energy; (3) divert, guide, or agitate the
stormwater flow; and (4) check eddy currents.
Baffle Chute
A drop structure in a channel with baffles for energy dissipation to permit the lowering of the hydraulic
energy gradient in a short distance to accommodate topography.
Base Flood Elevation
The elevation shown on the Flood Insurance Rate Map (FIRM) and found in the accompanying Flood
Insurance Study (FIS) for Zones A, AE, AH, A1-30, AR, V1-30, or VE that indicates the water surface elevation
resulting from the flood that has a 1% chance of equaling or exceeding that level in any given year.
Section 2: Abbreviations and Definitions
2.2 Definitions
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Calibration
Process of checking, adjusting, or standardizing operating characteristics of instruments and model
appurtenances on a physical model or coefficients in a mathematical model. The process of evaluating the
scale readings of an instrument in terms of the physical quantity to be measured.
Carrier Pipe
A pipe used to carry stormwater, water, or wastewater, as opposed to an exterior protective casing pipe.
Casing Pipe
An exterior protective pipe that encases a carrier pipe for various types of crossings, including roadways,
creeks, and railroads. Also known as encasement pipe.
Channel
A man-made drainageway or watercourse, generally constructed to straighten a stream or increase its
capacity.
Channel Roughness
Irregularities in channel configuration which attenuate the flow of water and dissipate its energy.
Chute
An inclined conduit or structure used for conveying water to a lower level.
City’s Engineer
A Professional Engineer, licensed by the State of Texas, who is the subject matter expert of the relevant
topic of discussion, and employed by the City of Denton.
Conduit
Any open or closed structure for conveying flowing water.
Corner Clip
ROW dedication at intersection corners to provide sufficient room for intersection visibility, pedestrian
access, and other street facilities.
Critical Flow
The state of flow for a given discharge at which the specific energy is a minimum with respect to the bottom
of the conduit. The Froude Number is equal to 1.0 for critical flow conditions.
Crown
The highest point on a transverse section of conduit or the highest point of a roadway cross-section.
Culvert
Large pipe or other conduit through which a small stream passes under a road or street.
Curb
A vertical or sloping structure located along the edge of a roadway, normally constructed integrally with
the gutter, which strengthens and protects the pavement edge and clearly defines the pavement edge to
vehicle operators.
Section 2: Abbreviations and Definitions
2.2 Definitions
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Dam
A barrier constructed across a watercourse for the purpose of creating a reservoir or diverting water from a
conduit or channel.
Degradation
The progressive general lowering of a stream channel by erosion, other than that caused by a constriction.
Department Reviewer
A member of a City of Denton department, designated by the Department Director, with subject matter
expertise related to the Design Criteria Manual who is designated as being responsible for the review of
design deviation requests.
Depression Storage
Collection and storage of rainfall in natural depressions after exceeding infiltration capacity of the soil.
Design Storm or Flood
The storm or flood which is used as the basis for design.
Detention
The storage of storm runoff for a controlled release during or immediately following the design storm.
1. Off-site detention - A detention pond located outside the boundary of the area it serves.
2. On-site detention - A detention pond which is located within and serves only a specific site or
subdivision.
3. Regional detention - Detention facilities provided to control excess runoff based on a watershed -wide
hydrologic analysis.
Development
Any man-made change to improved or unimproved real estate, including but not limited to, buildings or
other structures, paving, drainage, or utilities. Development activities include: subdivision of land;
construction or alteration of structures, roads, parking, fences, pools, signs, temporary uses, utilities, and
other facilities; installation of septic systems; grading; excavation, mining or drilling operations; deposit of
refuse, debris, or fill materials; and clearing of natural vegetative cover (with the exception of agricultural
activities as defined and as permitted). Routine repair and maintenance activities are exempted.
Development Project Facilitation
Division within the City of Denton that assists developers move projects through the City’s various
development review process and authorized to process the review of design deviation requests.
Drop Structures
A sloping or vertical section of a channel designed to reduce the elevation of flowing water without
increasing its velocity.
Energy Dissipaters
Engineered devices such as riprap aprons or concrete baffles placed at the outlet of stormwater conveyance
systems for the purpose of reducing the velocity, energy and turbulence of the discharged flow.
Section 2: Abbreviations and Definitions
2.2 Definitions
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Entrance Head
The head required to cause flow into a conduit or other structure; it includes both entrance loss and velocity
head.
Entrance Loss
Head lost in eddies or friction at the inlet to a conduit, headwall or structure.
Existing Traffic
Existing traffic conditions based on the most recent traffic counts. Existing traffic conditions do not include
the traffic created or associated with the development.
Flash Flood
A flood of short duration with a relatively high peak rate of flow, usually resulting from a high intensity
rainfall over a small area.
Flood Control
The elimination or reduction of flood losses by the construction of flood storage reservoirs, channel
improvements, dikes and levees, by-pass channels, or other engineering works.
Flood Hazard Area
Area subject to flooding by 1% chance floods.
Flood Management or Flood Hazard Mitigation
Any program or activity designed to reduce damages from flooding, including stream erosion.
Floodplain
The area that is subject to flooding from the 1% chance flood. The floodplain includes the regulatory
floodway and floodway fringe.
Floodway
The channel and adjacent lands of a watercourse that must be reserved in order to discharge the base flood
without increasing the water surface elevation more than the regulatory designated height.
Floodway Fringe
The area located within the floodplain and outside the floodway.
Freeboard
The distance between the normal operating level and the top of the side of an open conduit left to allow
for wave action, floating debris, or any other condition or emergency without overtopping the structure.
Frequency (of storms, floods)
Average recurrence interval of events, over long periods of time. Mathematically, frequency is the reciprocal
of the exceedance probability.
Froude Number
A flow parameter, which is a measure of the extent to which gravitational action affects the flow. A Froude
number greater than one (1) indicates supercritical flow and a value less than 1 subcritical flow. The simplest
Section 2: Abbreviations and Definitions
2.2 Definitions
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form of the Froude number is given by the following equation:
F = V / (g D)0.5 [Eqn. 2.1]
Where: V = Velocity
g = the acceleration due to gravity (32.2 ft/s2)
D = depth
Fully Developed Conditions
A description of hydrologic conditions in a watershed, if the watershed has been completely built out based
on the zoning and future land use maps of the City. If there is no designated future land use, the runoff
coefficient will be assumed to be (0.6) for purposes of determining fully developed water surface elevations.
This term is interchangeable with the term “Ultimate Developed Conditions”. This is not to be confused
with a Developed Floodplain as defined in Subchapter 9.2 of the DDC, which refers to the character of the
streambed itself.
Gabion
A wire container filled with rock and used in the construction of dams, retaining walls, and protection against
erosion.
Grade
1. The inclination or slope of a channel, canal, conduit, etc., or natural ground surface, usually expressed
in terms of the percentage of number of units of vertical rise (or fall) per unit of horizontal distance.
2. The elevation of the invert of the bottom of a conduit, canal, culvert, sewer, etc.
3. The finished surface of a canal bed, road bed, top of an embankment, or bottom of excavation.
Gutter
A generally shallow waterway adjacent to a curb used to convey stormwater.
Headwater
1. The upper reaches of a stream near its sources;
2. The region where ground waters emerge to form a surface stream;
3. The water upstream from a structure.
Hydraulic Control
The hydraulic characteristic which determines the stage-discharge relationship in a conduit. The control is
usually critical depth, tailwater depth, or uniform depth.
Hydraulic Grade Line
A line representing the pressure head available at any given point within the system.
Hydraulic Gradient
A hydraulic profile of the piezometric level of the water, representing the sum of the depth of flow and the
pressure head. In open channel flow, it is the water surface.
Hydraulic Jump
The hydraulic jump is an abrupt rise in the water surface which occurs in an open channel when water
Section 2: Abbreviations and Definitions
2.2 Definitions
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flowing at supercritical velocity is retarded by water flowing at subcritical velocity. The transition through
the jump results in a marked loss of energy, evidenced by turbulence of the flow within the area of the
jump. The hydraulic jump is sometimes used as a means of energy dissipation.
Hydraulics
A branch of science that deals with practical applications of the mechanics of water movement.
Hydrograph
A graph showing stage, flow, velocity, or other property of water versus time at a given point on a stream
or conduit. Examples include: Dimensionless Unit hydrograph, Unit Hydrograph.
Hydrology
The science dealing with the properties, distribution, and circulation of water on and below the Earth’s
surface and in the atmosphere.
Hyetograph
A histogram or graph of rainfall intensity versus time of storm.
Impervious
A term applied to a material through which water cannot pass or passes with great difficulty.
Infiltration
1. The entering of water through the interstices or pores of a soil or other porous medium.
2. The entrance of water from the ground into a sewer or drain through breaks, defective joints, or porous
walls.
3. The absorption of water by the soil, either as it falls as precipitation, or from a stream flowing over the
surface.
Inlet
Inlets are drainage structures used to collect surface water through grate or curb openings and convey it to
storm drains or direct outlet to culverts.
Inlets used for the drainage of roadway surfaces can be divided into four major classes:
1. Grate Inlets – These inlets include grate inlets consisting of an opening in the gutter covered by one or
more grates, and slotted inlets consisting of a pipe cut along the longitudinal axis with a grate or spacer
bars to form slot openings.
2. Curb-Opening Inlets – These inlets are vertical openings in the curb covered by a top slab.
3. Combination Inlets – These inlets usually consist of both a curb-opening inlet and a grate inlet placed
in a side-by-side configuration, but the curb opening may be located upstream of the grate.
4. Drop Inlet (Y-Inlet) -A storm drain intake structure typically located in unpaved areas. The inlet may
extend above the ground level with openings on one or more sides of the inlet or it may be flush with
the ground with a grated cover.
Intensity
As applied to rainfall, a rate usually expressed in inches per hour.
Interception
As applied to hydrology, refers to the process by which precipitation is caught and held by foliage, twigs,
Section 2: Abbreviations and Definitions
2.2 Definitions
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and branches of trees, shrubs and buildings, never reaching the surface of the ground, and then lost by
evaporation.
Invert
The floor, bottom, or lowest portion of the internal cross-section of a conduit.
Lag Time
The time difference between two occurrences such as between rainfall and runoff or pumping of a well and
effect on the stream. See Time of Concentration.
Level of Service
A qualitative measure of traffic flow and congestion, representing quality of service. It describes operational
conditions within a traffic stream, generally described in terms of such factors as speed and travel time,
freedom to maneuver, traffic interruptions, comfort and convenience, and safety.
Lining
Impervious material such as concrete, clay, grass, plastic, puddled earth, etc., placed on the sides and bottom
of a ditch, channel, and reservoir to prevent or reduce seepage of water through the sides and bottom
and/or to prevent erosion.
Lip
A small wall on the downstream end of an apron to break the flow from the apron.
Major Stream
Waterways with a contributing drainage area of one square mile or more.
Manning’s Coefficient
The coefficient of roughness used in Manning’s Equation for flow in open channels.
Manning’s Equation
A uniform flow equation used to relate velocity, hydraulic radius and the energy gradient slope.
Median
The portion of a divided roadway separating the opposing traffic flows. A median may be traversable or
non-traversable.
Median Opening
An opening in a non-traversable median that allows accessing or crossing the opposing traffic lanes.
Minimum building elevation
The elevation to which new and substantially improved structures within the floodway or within 200 feet of
the floodplain or SFHA are required to be elevated or floodproofed. This elevation would be equal 18 inches
above the 100-year water surface elevation based on fully developed conditions or 30 inches above the BFE
as indicated in the flood insurance study or, if the BFE is unavailable, 30 inches above the 100-year flood
elevation based on current development watershed conditions.
Section 2: Abbreviations and Definitions
2.2 Definitions
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Model
Mathematical systems analysis by computer, applied to evaluate rainfall-runoff relationships; simulate
watershed characteristics, predict flood and reservoir routings, or use other aspects of planning.
Nappe
The sheet or curtain of water overflowing a weir or dam. When freely overflowing any given structure, it has
a well-defined upper and lower surface.
Open Channel
A conduit in which water flows with a free surface.
Orifice
1. An opening with closed perimeter, and of regular form in a plate, wall, or partition through which water
may flow.
2. The end of a small tube, such as a Pilot tube, piezometer, etc.
Peak Flow (Peak Rate of Runoff)
The maximum rate of runoff during a given runoff event.
Percolation
To pass through a permeable substance such as ground water flowing through an aquifer.
Permeability
The property of a material which permits movement of water through it when saturated and actuated by
hydrostatic pressure.
Pervious
Applied to a material through which water passes relatively freely.
Pilot Channel
A constructed pathway that guides base streamflow or runoff along a specified route through a drainage
facility or drainage feature.
Porosity
1. An index of the void characteristics of a soil or stratum as pertaining to percolation; degree of
perviousness.
2. The ratio, usually expressed as a percentage, of (a) the volume of the interstices in a given quantity of
material, to (b) the total volume of the material.
Positive Overflow
When the inlets do not function properly, or when the design capacity of the conduit is exceeded, the excess
flow must be conveyed overland along a paved course. This could mean along a street or alley but could
require a concrete flume and the dedication of special drainage easements on private property.
Post-development
The condition of the given site and drainage area after the anticipated development has taken place.
Section 2: Abbreviations and Definitions
2.2 Definitions
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Precipitation
Any moisture that falls from the atmosphere, including snow, sleet, rain and hail.
Pre-development
The condition of the given site and drainage area prior to development.
Probable Maximum Flood
The flood that may be expected from the most severe combination of critical meteorological and hydrologic
conditions that are reasonably possible in the region.
Probable Maximum Precipitation
The critical depth-duration-area rainfall relationship for a given area during the seasons of the year which
would result from a storm containing the most critical meteorological conditions considered probable of
occurring.
Projected Growth Rate
The estimated growth rate per year for the study area based upon the average growth in the previous 5 -
year period along arterials in the vicinity of the proposed project.
Proposed Site Traffic Volumes
The number of vehicles per day and per hour projected to be generated by the development.
Rainfall Duration
The length of time over which a single rainfall event occurs.
Rainfall Frequency
The average recurrence interval of rainfall events.
Rainfall Intensity
The rate of accumulation of rainfall, usually in inches or millimeters per hour.
Rational Formula
A traditional method of computing peak flow using intensity of the storm rainfall.
Reach
Any length of river or channel. Usually used to refer to sections which are uniform with respect to discharge,
depth, area or slope, or sections between gaging stations.
Recurrence Interval
The average interval of time within which a given event will be equaled or exceeded once. For an annual
series (as opposed to a partial duration series) the probability of occurrence in anyone year is the inverse of
the recurrence interval. Thus, a flood having a recurrence interval of 100 years has a 1% probability of being
equaled or exceeded in any one year.
Regulatory Floodway
The channel of a river or other watercourse and the adjacent land areas that must be reserved in order to
discharge the base flood without cumulatively increasing the water surface elevation more than a
Section 2: Abbreviations and Definitions
2.2 Definitions
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designated height.
Retention
The storage of a portion or all of the storm runoff for purposes of permanent use of the retained water.
Retention facilities are similar to detention facilities with the main difference being that all of the storm
runoff will not be released to the downstream drainage network.
Return Period
See Recurrence Interval
Reynold’s Number (Re)
A flow parameter which is a measure of the viscous effects on the flow. Typically defined as shown in the
equation below:
Re = (V. D) / v [Eqn. 2.2]
Where: V = Velocity
D = Depth
v = kinematic viscosity of the fluid
Riprap (Revetment)
Forms of bank protection, usually using rock or concrete.
Routing
Routing is a technique used to predict the temporal and spatial variations of a flood wave as it traverses a
river reach or reservoir. Generally, routing technique may be classified into two categories - hydrologic
routing and hydraulic routing.
Right-of-Way
A designated section of a street, sidewalk, alley, waterway or utility easement and/or related facilities, that
is dedicated for municipal usage.
Right-of-Way Width
The shortest horizontal distance between the lines which delineate the right-of-way of a street.
Runoff
That part of the precipitation which reaches a stream, drain, sewer, etc., directly or indirectly.
1. Direct Runoff - The total amount of surface runoff and subsurface storm runoff which reaches stream
channels.
2. Overland Runoff - Water flowing over the land surface before it reaches a definite stream channel or
body of water.
Runoff Coefficient
A decimal number used in the Rational Formula which defines the runoff characteristics of the drainage
area under consideration. It may be applied to an entire drainage basin as a composite representation or it
may be applied to a small individual area such as one residential lot.
Section 2: Abbreviations and Definitions
2.2 Definitions
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Runoff Total
The total volume of flow from a drainage area for a definite period of time such as a day, month, or a year,
or it may be for the duration of a particular storm.
Scour
The erosive action of running water in streams or channels in excavating and carrying away material from
the bed and banks.
SCS Runoff Curve Number
Index number used by the National Resource Conservation Service, formerly the Soil Conservation Service,
as a measure of the tendency of rainfall to run off into streams rather than evaporate or infiltrate.
Sediment
Material of soil and rock origin transported, carried, or deposited by water.
Sedimentation Basin
A sediment control basin required to catch runoff from common drainage areas with 10 acres or more
disturbed at one time during any phase of development that dewaters from the surface unless infeasible.
Sidewalk
A paved area within the street ROW or sidewalk easement specifically designed for pedestrians and/or
bicyclists.
Sight Distance
The distance visible to the driver of a passenger vehicle measured along the normal travel path of a roadway
from a designated location and to a specified height above the roadway when the view is unobstructed by
traffic.
Slope, Critical
The slope or grade of a channel that is exactly equal to the loss of head per foot resulting from flow at a
depth that will give uniform flow at critical depth; the minimum slope of a conduit which will produce critical
flow.
Slope, Friction
The friction head or loss per unit length of channel or conduit. For uniform flow the friction slope coincides
with the energy gradient, but where a distinction is made between energy losses due to bends, expansions,
impacts, etc., a distinction must also be made between the friction scope and the energy gradient. The
friction slope is equal to the bed or surface slope only for uniform flow in uniform open channels.
Soffit
In a stormwater pipe, the uppermost point of the interior of the pipe wall. The crown is the uppermost point
on the outside of the pipe wall.
Spillway
A waterway in or about a dam or other hydraulic structure, for the overflow of excess water.
Section 2: Abbreviations and Definitions
2.2 Definitions
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Standard Details
A collection of uniform detail drawings of structures or devices adopted as standard construction details by
the City of Denton.
Steady Flow
Open channel flow is said to be steady if the depth of flow does not change or if it can be assumed to be
constant during the time interval of consideration.
Stormwater Facility Maintenance Agreement or Maintenance Agreement
A legal agreement between the City of Denton and a property owner, including HOAs and POAs, for
perpetual maintenance of a structural BMP.
Stream
A natural drainageway that conveys stormwater, may also be referred to as a creek. References to a stream
or creek in this Manual refer to the entire stormwater carrying component of the stream to the limits of the
floodplain, not just to the streambed.
Stilling Basin
Pool of water conventionally used, as part of a drop structure or other structure, to dissipate energy.
Stopping Sight Distance
The distance required by a driver of a vehicle, traveling at a given speed, to bring the vehicle to a stop after
an object on the roadway becomes visible. It includes the distance traveled during driver perception time,
reaction time, and the vehicle braking distance.
Storage Length
The portion of an auxiliary lane required to store the number of vehicles expected to accumulate in the lane
during an average peak period.
Storm Hydrology
The branch of hydrology that concentrates on the calculation of runoff from storm rainfall.
Stormwater Management
The control of storm runoff on-site or on small streams, by means of land use restrictions, detention storage,
erosion control, and/or drainage measures.
Stormwater Model
Mathematical representation of a stormwater network.
Study area
The boundaries of the assessment area as determined by the City’s Engineer.
Subcritical Flow
The Froude Number is less than 1.0 for subcritical flow conditions.
Supercritical Flow
The Froude Number is greater than 1.0 for supercritical flow conditions.
Section 2: Abbreviations and Definitions
2.2 Definitions
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Tailwater
The depth of flow in the stream directly downstream of a drainage facility.
Time of Concentration
The estimated time in minutes required for runoff to flow from the most remote section of the drainage
area to the point at which the flow is to be determined.
Total Head Line (Energy Line)
A line representing the energy in flowing water. The elevation of the energy line is equal to the elevation of
the flow line plus the depth plus the velocity head plus the pressure head.
Traffic Queue
Vehicles within a storage queue awaiting traffic movement in a single lane, within one traffic signal cycle.
Trash Rack
Racks, gratings, or mesh designed so as to prevent leaves and rubbish from plugging the outlets from a
dam or detention basin.
Trip Distribution
An estimate of the spatial pattern of trips or other flows between given sets of origins and destination pairs.
Trip distribution models connect the trip origins and destination, estimated by the trip generation models
to create estimated trips based on the Base year and Buildout years (24 hour counts or turning movement
counts). Different trip distribution models are developed for each of the trip purposes for which trip
generation has been estimated.
Trunk Line
The main line of a storm drain system extending from manhole to manhole or from manhole to outlet
structure.
TxDOT Highways
State-operated highways that include Farm to Market (FM) roadways, State Highways (SH), Interstate
Highway (IH), IH Frontage Roads, and United States (US) Highways.
Uniform Channel
A channel with a constant cross-section and roughness.
Uniform Flow
Open channel flow is said to be uniform if the depth of flow is the same at every section of the channel.
Unit Hydrograph
The direct runoff hydrograph resulting from one inch of precipitation excess distributed uniformly over a
watershed for a specified duration.
Valley Storage
Refers to the water storage capacity of a stream and is a volume that is measured below the base flood
elevation. Restrictions on loss of valley storage refer to compensation for the loss of storage caused by fill
below the base flood elevation.
Section 2: Abbreviations and Definitions
2.2 Definitions
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Velocity Head
The energy per unit weight of water due to its velocity (v). The velocity head also represents the vertical
distance water must fall freely under gravity to reach its velocity (v). The velocity head can be computed
from the following equation:
Velocity Head = v2 / 2 g [Eqn. 2.3]
Where: v = velocity
g = acceleration due to gravity (32.2 ft/s2)
Water Year
The water year commonly used in the United States is the period from October 1 to September 30 of the
following calendar year.
Watershed
The area contributing storm runoff to a stream or drainage system. Other terms are drainage area, drainage
basin and catchment area.
Zone of Influence
A point downstream where the increased discharge from a proposed development results in 0.00’ increase
in flood elevation.
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Section 3: Solid Waste Design Criteria
3.1 Overview
The purpose of Section 3 - Solid Waste Design Criteria of this DCM is to provide basic criteria and standards
for the development and maintenance of solid waste and recycling container enclosures.
The Solid Waste Design Criteria established in this Manual shall apply as set forth in:
A. City of Denton Code of Ordinances – Chapter 24,
B. DDC Subchapter 7, Section 7.2 – Applicability, and
C. DDC Subchapter 7, Section 7.12 – Solid Waste and Recycling Design Standards.
The City Code of Ordinances states that the City of Denton shall be the exclusive provider of solid waste
collection and disposal services within the City Limits including, but not limited to, services provided for
preconstruction activities, construction activities, and residential, multifamily, and commercial activities. All
contractors and subcontractors should call City of Denton Customer Service (940-349-8700) to initiate
service. Third-party solid waste providers may not be used for any on-site solid waste services within the
City Limits.
3.2 Design Standards
3.2.1 General
A. Nonresidential on-site solid waste and recycling container enclosures shall be located on each
platted lot of non-residential property and shall be constructed and maintained by the property
owner or developer and made available for use by the City of Denton Solid Waste Department or
commercial recycling service provider.
B. Nonresidential on-site solid waste and recycling container enclosures shall be available for the
storage of all municipal solid waste and recyclables generated for each platted property. The City
reserves the ability to determine whether any parcel or area (for example, Downtown Square, strip
centers, multifamily residential, etc.) must have shared container service or an alternative service.
Container enclosures shall be of adequate size to contain all solid wastes, liquid wastes, and
recyclables generated on the property, including, but not limited to, municipal solid waste,
recyclables, grease and oils, process by-products and wastes, hazardous waste, medical waste, and
any special wastes, contained in accordance with Chapter 24, City of Denton Code of Ordinances.
C. The container enclosures shall meet the Container Enclosure and Storage Space Dimensional
Requirements prescribed in Section 3.2.2 of this Manual, as well as Chapter 469 of the Texas
Government Code, as amended.
D. New nonresidential uses of 999 square feet (sq. ft.) or less will be evaluated by City staff to
determine the applicability of constructing an enclosure. Trash and recycling carts may be
appropriate, thereby eliminating the need for the construction of an enclosure.
E. Cart storage may be utilized on property converted from a residential to non-residential use if the
converted property is a structure of less than 2,500 gross sq. ft., has a waste generation rate
applicable for cart service, and is in an area where commercial cart service is available.
F. Proposed future building expansion (evaluated at 50% or more of the current square footage) and
Section 3: Solid Waste Design Criteria
3.2 Design Standards
3.2.2 Container Enclosure and Storage Space Dimensional Requirements
Design Criteria Manuals 21
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phased development shall be considered in site design with regard to sizing, location(s), and access
of future solid waste and recyclables container enclosures. Solid waste and recycling areas necessary
for future building expansion shall be available, but need not be utilized, nor container enclosures
constructed, until future building expansion occurs.
G. Containers for solid waste and recycling service shall be screened from the public right-of-way
(ROW) and from adjacent property owners.
H. Proper construction of the container enclosures shall be completed prior to final approval of the
development or property by the City’s Solid Waste Department.
I. Container enclosure designs shall be consistent with the engineering drawings and specifications
shown in the Solid Waste and Recycling Container Enclosure Construction Drawings in the City of
Denton Standard Details.
3.2.2 Container Enclosure and Storage Space Dimensional Requirements
A. All single front-load commercial container enclosures shall have inside walls with dimensions
measuring a minimum of 13 feet wide and 11.5 feet deep. The rear face of the bollard must be
three (3) feet from the rear of the enclosure and the front of the bollard must be eight (8) feet from
the front of the enclosure, leaving six (6) inches of space equal to the size of the bollard. Only solid
waste and recycling containers are allowed in the enclosures. Other storage containers such as
grease and oil receptacles, and other items shall be stored and located in a different enclosure.
These enclosures shall be located where they will not impede the service of the solid waste and/or
recycling containers.
B. All dual front-load commercial container enclosures shall have inside walls with dimensions
measuring 26 feet wide and 11.5 feet deep. The rear face of the bollard must be three (3) feet from
the rear of the enclosure and the front of the bollard must be eight (8) feet from the front of the
enclosure, leaving six (6) inches of space equal to the size of the bollard. Only solid waste and
recycling containers are allowed in the enclosures. Other storage containers such as grease and oil
receptacles, and other items shall be stored and located in a different enclosure. These enclosures
shall be located where they will not impede the service of the solid waste and/or recycling
containers.
C. In the rare case where it is not possible to fit typical front-load enclosures as required above, a
design deviation request may be submitted to the City’s Solid Waste Department for the
consideration of the following two alternatives:
1. Single side-load commercial container enclosures having inside walls with dimensions
measuring a minimum of 10 feet wide and eight (8) feet deep. The rear face of the bollard
must be one (1) foot from the rear of the enclosure, and the front of the bollard must be 6.5
feet from the front of the enclosure, leaving six (6) inches of space equal to the size of the
bollard. Only solid waste and recycling containers are allowed in the enclosures.
2. Dual side-load commercial container enclosures having inside walls with dimensions
measuring 20 feet wide and eight (8) feet deep. The rear face of the bollard must be one (1)
foot from the rear of the enclosure, and the front of the bollard must be 6.5 feet from the
front of the enclosure, leaving six (6) inches of space equal to the size of the bollard. Only
solid waste and recycling containers are allowed in the enclosures.
D. All roll-off compactor enclosures shall have inside walls with dimensions measuring a minimum of
16 feet wide. The depth of the inside walls must accommodate the compactor size selected.
Section 3: Solid Waste Design Criteria
3.2 Design Standards
3.2.2 Container Enclosure and Storage Space Dimensional Requirements
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E. The City of Denton Standard Details contain the required construction specifications for container
enclosures and storage spaces.
F. All developments shall be required to install container enclosures as specified in Table 3.2-A .
G. Nonresidential uses that are not required to meet the above storage space and enclosure
requirements, will be reviewed for adequate solid waste and recyclables enclosures based on site -
specific information and the following Solid Waste and Recycling Design Factors:
1. Type of business;
2. Waste generation potential;
3. Waste generation of similar businesses;
4. Square footage of the development and structures;
5. Number of floors;
6. Location of the business;
7. Hours of business operation;
8. Business site plan; and
9. Phased development and future use plans.
Table 3.2-A: Minimum Container Enclosure Requirements
Development Use Required Enclosure(s) or Container(s)
RESIDENTIAL
Single-family Residential curbside cart pick-up Townhomes – 4 units or fewer
RESIDENTIAL - MULTIFAMILY
5 – 48 units 2 front-load containers enclosed
49 – 64 units 3 front-load containers enclosed
65 – 200 units
1 compactor and 1 front-load container for recycling
or
4 front-load containers enclosed
200+ units 1 compactor and 1 front-load container enclosed
GENERAL COMMERCIAL
1 – 15,000 sq. ft. 2 front-load containers enclosed
15,001 – 50,000 sq. ft. 3 front-load containers enclosed
50,001 – 200,000 sq. ft.
1 compactor and 1 front-load container for recycling
or
4 front-load containers enclosed
Over 200,000 sq. ft. 1 compactor and 1 front-load container enclosed
Notes:
[1] For industrial/warehouse development, container(s) do not require enclosures, but container(s) must be screened from public view.
Section 3: Solid Waste Design Criteria
3.2 Design Standards
3.2.4 Container Enclosure Design Requirements
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3.2.3 Container Enclosure Design Requirements
A. Materials used for container enclosure construction shall be compatible with the architecture and
appearance of the main building and may include the following materials:
1. Concrete Block – Tinted, colored, painted, or with textured facing;
2. Concrete – Poured or tilt wall construction;
3. Brick - Double brick thickness minimum;
4. Stone;
5. Metal;
6. Wood;
7. Vinyl;
8. Composite Material; or
9. Any combination of materials 1-8.
B. Front-load and side-load commercial enclosures shall have walls constructed to a minimum height
of six (6) feet, or as tall as required to conceal the container. Compactor enclosure walls must be a
minimum height of eight (8) feet, in order to conceal the compactor and mechanical equipment.
C. Gates shall be required when the interior of the enclosure is visible from the public ROW or when
it is visible from the lot of an adjacent property owner.
D. Personal access side gates are recommended as a feature of all gated enclosures. These gates
should be fitted with emergency egress strike bars.
3.2.4 Enclosure Access, Placement, Ingress, and Egress Requirements
A. The required number of enclosures will be determined based on the type and size of the
development.
B. Dumpster enclosures must be angled no more than 30 degrees from the center line of the solid
waste collection vehicle route.
C. There must be 50 feet or more of unobstructed truck access in front of each container.
D. For safety purposes, solid waste collection vehicles will not back up more than 100 feet after
servicing a container and will not make any turns while backing up.
E. Turn Radii Requirements: The turn radii must be a minimum of 30 feet for any intersection to
accommodate occasional turning trucks for weekly pick-up.
F. The collection vehicle will travel through a site once without backtracking. For an example of a
typical solid waste collection route, take note of the Typical Solid Waste Collection Route Schematic
shown in Figure 3.1 below.
G. Container enclosures shall not be located in fire apparatus access roads, public ROW, public utility
easements, or sidewalk areas.
H. No solid waste container enclosure shall be located within the required front yard or protrude in
front of any buildings along the designated lot frontage.
Section 3: Solid Waste Design Criteria
3.2 Design Standards
3.2.4 Enclosure Access, Placement, Ingress, and Egress Requirements
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I. Parking spaces shall begin after the enclosure gates open. No obstructions permitted around
enclosure or gate openings equivalent to the length of the gate.
J. The location of container enclosures may not cause the obstruction of traffic for excessive lengths
of time while being serviced.
K. The solid waste service truck shall be on the property owner’s property during service operations,
if the site design permits.
L. Ingress and egress routes shall be designed to facilitate exiting the property in a forward driving
direction for all interstate and state roads, arterial streets, and collector streets with four lanes. See
the Backing Clearance Schematic in Figure 3.2 below.
M. Utility wires and structure overhangs should have a minimum height clearance of 20 feet along the
ingress and egress route. No utility wires shall extend over the enclosure approach and service area.
N. Container enclosures shall be located a minimum of 30 feet away from any storm drain or drainage
flow areas. Where site configuration allows, container enclosures shall also be placed downslope of
any storm drain.
Figure 3.1 Typical Solid Waste Collection Route Schematic
Section 3: Solid Waste Design Criteria
3.2 Design Standards
3.2.5 Alleyway Access
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Figure 3.2 Backing Clearance Schematic
3.2.5 Alleyway Access
An alley (residential or commercial) is a private street designed to provide fire and solid waste collection
access to the rear or side of a lot. Dead ends are not permitted in alleys. Alleys used for solid waste collection
must comply with the Transportation Design Criteria in Section 5 of this Manual. Alleyway access must
comply with the following criteria:
A. Design Factors:
1. Turn Radius;
2. Street Widths;
3. Horizontal and Vertical Clearances;
4. Pavement; and
5. Multifamily Units
B. Turn Radii Requirements: Texas Department of Transportation (TxDOT) recommends, via AASHTO,
that the turn radii be a minimum of 30 feet for alley-to-alley intersections with occasional turning
trucks for weekly trash pick-up per TCEQ regulations. Turn radii must be sufficient for side-load
residential collection vehicles to navigate alleyways lined with trash and recycle carts on both sides.
See Figure 3.3 below.
C. Alley Width Requirements: Alleys must be paved and a minimum of 15-ft. wide. Additionally, alleys
must be wide enough to accommodate carts, to allow vehicles to safely service carts, and to comply
with the Transportation Design Criteria in Section 5 of this Manual.
D. Horizontal and Vertical Clearance Requirements: Balconies, landscaping, or other elements shall not
encroach into approved horizontal or vertical clearances for vehicle travel, backing, loading, or other
operations along any alley.
1. The horizontal operating travel clearance must be 20 feet.
2. The vertical operating travel clearance must be 15 feet.
Section 3: Solid Waste Design Criteria
3.2 Design Standards
3.2.5 Alleyway Access
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E. Pavement Requirements: Pavement must be built to standards that allow two (2) 33-ton vehicles to
travel down all alleys twice each service day. Alternatively, a responsible party, HOA, or POA must
provide a waiver recorded with the property for potential damage caused over time by normal
hauler operations.
F. Multifamily Unit Requirements: Any attached residential arrangement of five (5) or more dwelling
units per lot will fall under the Commercial Business Category as defined by City of Denton Code
of Ordinances 24-2 Definitions (Commercial), which requires a solid waste and recycling storage
facility (container enclosure). See the Site Plan Criteria for Municipal Solid Waste & Recyclables
Storage & Enclosure Requirements in the City of Denton Standard Details.
Figure 3.3 Solid Waste Collection Vehicle Turn Radius Schematic
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Section 4: Stormwater Design Criteria
4.1 Overview
The purpose of Section 4 - Stormwater Design Criteria of this DCM is to establish standard principles and
practices for the design and construction of storm drainage systems, to implement the policies set forth in
the DDC and the City of Denton Code of Ordinances, Subpart B, Chapter 30 (Denton Flood Prevention and
Protection Ordinance) within the City of Denton, Texas and its extraterritorial jurisdictions.
The following documents govern the design and construction of stormwater drainage systems:
A. City of Denton Code of Ordinances, Chapter 30, Flood Prevention and Protection;
B. DDC Subchapter 7.4 – Environmentally Sensitive Areas;
C. DDC Subchapter 7.5 – Drainage Standards;
D. iSWMTM Planning Technical Manual Document;
E. iSWMTM Water Quality Technical Manual Document;
F. iSWMTM Hydrology Technical Manual Document;
G. iswmTM Hydraulics Technical Manual Document;
H. iSWMTM Site Development Controls Technical Manual Document;
I. iSWMTM Construction Controls Technical Manual Document;
J. iSWMTM Construction Control Standard Details Technical Manual Document; and
K. iSWMTM Landscape Technical Manual Document.
The design factors, formulae, graphs, and procedures specified in this document are intended for use as
minimum engineering criteria for the design of drainage systems with regards to the quantity, rate of flow,
method of collection, storage, conveyance, detention, and disposal of stormwater. Responsibility for
actual design remains with the design engineer. Users of this Manual should be knowledgeable and
experienced in the theory and application of drainage engineering.
The stormwater criteria contained in this Manual supersede any design criteria contained in the iSWMTM
Planning, Water Quality, Hydraulics, and Hydrology Technical Manual Documents. The stormwater design
criteria contained in this Manual do not supersede the criteria contained in the DDC or Chapter 30 of the
City of Denton Code of Ordinances. Any revisions to the DDC or Chapter 30 of the City of Denton Code of
Ordinances shall supersede the criteria in this Manual. In case of any conflict, the more stringent
requirement shall apply.
The requirements of this Manual shall apply to all public facilities and to private facilities when the
performance of such private facility has an effect on the public interest, health, or welfare.
4.1.0 Organization
Section 4 - Stormwater Design Criteria is categorized as follows:
A. Overview
B. Design Focus
Section 4: Stormwater Design Criteria
4.2 Design Focus
4.1.0 Organization
Design Criteria Manuals 28
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C. Design Storms
D. Hydrologic Methods
E. Acceptable Downstream Conditions for Open Channels and Floodplains
F. Stormwater System Design
G. Culverts
H. Bridges
I. Detention Facilities
J. Energy Dissipation
K. Floodplain
L. Drainage and Floodplain Easements
M. Water Quality
N. Stormwater Facility Maintenance Agreements
4.2 Design Focus
The design criteria for stormwater management primarily focus on:
4.2.1 Streambank Protection - Regulate discharge from the site to minimize downstream bank and
channel erosion;
4.2.2 Flood Mitigation and Conveyance - Control runoff within and from the site to minimize flood risk
to people and properties for the conveyance storm and the 1% chance storm; and
4.2.3 Water Quality - Reduce pollutants from stormwater by either infiltrating the water quality volume,
or removing 80% of total suspended solids (TSS) from any “Water Quality” storm event discharge.
4.3 Design Storms
Design is typically based on four (4) storm events, as detailed in Table 4.3-A.
Table 4.3-A: Design Storm Events
Storm Event Name Storm Event Description
“Water Quality” Criteria based on a volume of 1.5 inches of rainfall, not storm frequency
“Streambank Protection” 1-year, 24-hour storm event
“Conveyance” 25-year, 24-hour storm event
“Flood Mitigation” 100-year, 24-hour storm event
Notes:
[1] Throughout the manual, the storms will be referred to by their storm event names.
Drainage facilities shall be designed utilizing the “Flood Mitigation” storm event. Replacement or
modification of existing drainage facilities shall not reduce capacity , but such facility replacements or
modifications may be designed according to the requirements of the specific project and may utilize the
“Conveyance” storm as the design storm event, through an approved design deviation request.
Section 4: Stormwater Design Criteria
4.4 Hydrologic Methods
4.4.1 Types of Hydrologic Methods
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4.4 Hydrologic Methods
4.4.1 Types of Hydrologic Methods
The following empirical hydrologic methods support hydrologic site analysis for the design methods and
procedures included in this Manual:
A. Rational Method;
B. SCS Unit Hydrograph Method;
C. Modified Rational Method;
D. Snyder’s Unit Hydrograph Method; and
E. USGS & TxDOT Regression Equations
Table 4.4-A lists the hydrologic methods and the circumstances when they may be used in various analysis
and design applications. Table 4.4-B provides some additional constraints on the use of several methods.
Table 4.4-A: Applications of the Hydrologic Methods
Method Rational
Method SCS Method Modified
Rational
Snyder’s
Unit
Hydrograph
Method
USGS &
TxDOT
Equations
Streambank Protection Volume (SPV) ✓ ✓
Flood Mitigation Discharge (Qf) ✓ ✓ ✓
Storage Facilities ✓ ✓ ✓
Outlet Structures ✓ ✓
Gutter Flow and Inlets ✓ ✓
Storm Drain Pipes ✓ ✓ ✓
Culverts ✓ ✓ ✓ ✓
Bridges ✓ ✓
Small Ditches ✓ ✓ ✓
Open Channels ✓ ✓ ✓ ✓
Section 4: Stormwater Design Criteria
4.5 Acceptable Downstream Conditions for Open Channels and Floodplains
4.5.1 Rainfall Estimation
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Table 4.4-B: Constraints on Using Hydrologic Methods
Method Size Limitations 1 Used for Estimating
Rational 2 0 – 100 acres Peak flows and design of small site or subdivision storm sewer systems.
Modified Rational 3 0 – 200 acres Runoff volumes for storage design.
Unit Hydrograph (SCS) 4 Any Size Peak flows and hydrographs for all design applications.
Unit Hydrograph (Snyder’s) 5 1 acre and larger Peak flows and hydrographs for all design applications.
TxDOT Regression Equations 6 10 – 100 sq. mi. Peak flows for rural design applications.
USGS Regression Equations 6 3 – 40 sq. mi. Peak flows for urban design applications.
Notes:
[1] Size limitation refers to the drainage basin for the stormwater management facility (e.g., culvert, inlet).
[2] Acceptable for small, highly impervious drainage areas, such as parking lots and roadways draining into inlets and gutters.
[3] Used for conceptualizing; the engineer of record must use iSWM™ Hydrology Technical Manual Document when using this method.
[4] Refers to SCS routing methodology included in many readily-available programs (such as HEC-HMS or HEC-1) which utilize it.
[5] Refers to Snyder’s methodology included in many readily-available programs (such as HEC-HMS or HEC-1) which utilize it.
[6] The USGS and TxDOT equations should not be used when there are significant storage areas within the drainage basin or where other
drainage characteristics indicate general regression equations are not appropriate.
4.4.2 Rainfall Estimation
Rainfall intensities, provided in Table 5.3 of the iSWMTM Hydrology Technical Manual, are based on Atlas 14
and shall be used for all hydrologic analysis within Denton County.
4.5 Acceptable Downstream Conditions for Open Channels and
Floodplains
Stormwater discharge from a development shall not cause adverse impacts to adjacent, upstream, or
downstream properties or facilities. The design of a storm drain facility must account for the offsite flows
that are routed through the development, flows generated by the development, and the impacts of the
development and the drainage system on downstream facilities.
4.5.1 Downstream Assessments
The downstream impacts of development must be carefully evaluated for the two (2) focus areas of
Streambank Protection and Flood Mitigation (See Section 4.2 of this Manual). The purpose of the
downstream assessment is to protect downstream properties from increased flooding and downstream
channels from increased erosion potential due to upstream development. The importance of the
downstream assessment is particularly evident for larger sites or developments that have the potential to
dramatically impact downstream areas. The cumulative effect of smaller sites, however, can be just as
dramatic and, as such, following the Focus Areas is just as important for the smaller sites as it is for the
larger sites.
A downstream assessment will be required for all developments which alter flow patterns or increase the
amount of impervious surface and do not limit the peak discharge to pre-development conditions at each
outfall from their site. The assessment shall extend from the outfall of a proposed development to a point
downstream where there is no calculated increase in WSEL (water surface elevation) or mean velocity within
the receiving stream or storm drainage system. The City shall be consulted to obtain records and maps
related to the National Flood Insurance Program (NFIP) and the availability of Flood Insurance Studies (FIS)
Section 4: Stormwater Design Criteria
4.5 Acceptable Downstream Conditions for Open Channels and Floodplains
4.5.2 Adverse Impacts
Design Criteria Manuals 31
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and Flood Insurance Rate Maps (FIRMs) which will be helpful in this assessment. The assessment must
include the following properties:
A. Hydrologic analysis of the pre- and post-development on-site conditions.
B. Drainage path that defines extent of the analysis.
C. Capacity analysis of all existing constraint points along the drainage path, such as existing
floodplain developments, underground storm drainage systems culverts, bridges, tributary
confluences, or channels.
D. Offsite undeveloped areas are considered as “full y developed” for both the pre- and post-
development analyses.
E. Evaluation of peak discharges and velocities for three (3) 24-hour storm events:
1. “Streambank protection” storm
2. “Conveyance” storm
3. “Flood Mitigation” storm
F. Separate analysis for each major outfall from the proposed development .
Once the analysis is complete, the designer must answer the following questions at each determined
junction downstream:
A. Are the post-development discharges greater than the pre-development discharges?
B. Are the post-development velocities greater than the pre-development velocities?
C. Are the post-development velocities greater than the velocities allowed for the receiving system?
D. Are there any increases in post-development flood heights above the pre-development flood
heights?
These questions shall be answered for each of the three (3) storm events. The answers to these questions
will determine the necessity, type, and size of non-structural and structural controls to be placed on-site or
downstream of the proposed development.
Section 2.0 of the iSWMTM Hydrology Technical Manual, as amended, gives additional guidance on
calculating the discharges and velocities, as well as determining the downstream extent of the assessment.
4.5.2 Adverse Impacts
Downstream Assessments shall evaluate the capacity of the downstream system within the Zone of Influence
(ZOI). If the downstream system has less than fully developed capacity, the study shall demonstrate the
development will produce no adverse impacts during the one (1), 25, and 100-year storm events. No adverse
impacts may include, but are not limited to:
A. No new or increased flooding of existing structures;
B. Zero increases (0.00’) in water surface elevations unless contained within the banks of an existing
channel including 1-ft. freeboard. Dry lane requirements set forth in Section 4.6.2 shall also be met;
C. Increasing channel velocity is prohibited where existing velocities are erosive. Any increase in
channel velocity in other areas must remain below the maximum allowable velocity as defined in
Table 4.6-E;
D. No increases in downstream discharges caused by the proposed development that, in combination
with off-site discharges, exceeds the existing capacity of the downstream storm drainage system;
E. The Downstream Assessment shall extend to a point downstream, known as the ZOI, where the
proposed development creates no adverse impacts. The ZOI will be defined by a detailed hydrologic
and hydraulic modeling analysis. The City’s Engineer may require analysis beyond the ZOI
Section 4: Stormwater Design Criteria
4.5 Acceptable Downstream Conditions for Open Channels and Floodplains
4.5.4 Stormwater Diversions
Design Criteria Manuals 32
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established by the Engineer of Record based on the criteria above and known flooding issues. ZOI
does not automatically end based the rule of thumb known as the "10% rule"; and
F. If the subject development is part of a larger development, the Downstream Assessment must
include the larger development, and the ZOI shall be determined based on the entire property.
4.5.3 Stormwater Diversions
Diversion of stormwater away from the natural watercourse or existing discharge points will not be allowed,
except within the property boundaries controlled by the developer under the following conditions:
A. The stormwater is returned to its natural flowing watercourse prior to leaving the developer's
property, or
B. A timing analysis of the existing and diverted hydrograph must be performed to confirm that the
peak flow rate has not been increased at the point that it reenters the watercourse, as a result of
the diversion. The City’s Engineer may require additional downstream analysis if there are known
downstream flooding or volume-sensitive areas.
4.5.4 Streambank Protection
There are two (2) options by which a developer can provide adequate streambank protection downstream
of a proposed development. The first step is to perform the required downstream assessment as described
earlier in Section 4.5.1 of this Manual. If it is determined that the proposed project does not exceed
acceptable downstream velocities or the downstream conditions are improved to adequately handle the
increased velocity, then no additional streambank protection is required. If the downstream a ssessment
shows that the velocities are within acceptable limits, then no streambank protection is required. Acceptable
limits for velocity control are provided in Table 4.6-D and Table 4.6-E of this Manual. If existing stream
velocities exceed the maximum allowable velocities, then no increase in velocities will be permitted. If the
downstream assessment shows an increase in velocity beyond the acceptable limits, then on-site or
downstream improvements are required for streambank protection, easements or right -of-entry
agreements will need to be obtained in accordance with Section 4.12 of this Manual, and one of the two
options below must be utilized for streambank protection.
Option 1: Reinforce/Stabilize Downstream Conditions
If the increased velocities are greater than the allowable velocity of the downstream receiving system, then
the developer must reinforce/stabilize the downstream conveyance system. The proposed modifications
must be designed so that the downstream system is protected from the post-development velocities. The
developer must provide supporting calculations and/or documentation that the downstream velocities do
not exceed the allowable range once the downstream modifications are installed.
Allowable bank protection methods include stone riprap, gabions, and bio -engineered methods. Sections
3.2 and 4.0 of the iSWMTM Hydraulics Technical Manual give design guidance for designing stone riprap for
open channels, culvert outfall protection, riprap aprons for erosion protection at outfalls, and riprap basins
for energy dissipation.
If the downstream receiving system is designated as an Environmentally Sensitive Area (ESA) this option
may not be viable. See Section 7.4 of the DDC for more information about the various types of ESAs,
permitted encroachments, and processes for assessing and modifying ESAs.
Option 2: Install Stormwater Controls to Maintain Existing Downstream Conditions
The developer must use on-site controls to keep downstream post-development discharges at or below
Section 4: Stormwater Design Criteria
4.5 Acceptable Downstream Conditions for Open Channels and Floodplains
4.5.5 Flood Mitigation
Design Criteria Manuals 33
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allowable velocity limits. The developer must provide supporting calculations and/or documentation that
the on-site controls will be designed such that downstream velocities for the three (3) storm events
(“Streambank Protection”, “Conveyance”, and “Flood Mitigation”) are within an allowable range once the
controls are installed.
4.5.5 Flood Mitigation
A. Introduction
Flood analysis is based on the “Flood Mitigation” storm event (see Table 4.3-A). The intent of the
flood mitigation criteria is to provide for public safety; minimize on-site and downstream flood
impacts from the “Flood Mitigation” storm event; maintain the boundaries of the mapped 100-year
floodplain; and protect the physical integrity of the on-site stormwater controls and the
downstream stormwater and flood mitigation facilities.
Flood mitigation must be provided for on-site conveyance systems, as well as downstream outfalls
as described in the following sections.
B. Flood Mitigation Design Options
There are three (3) options by which a developer may address downstream flood mitigation as
discussed below. When on-site or downstream modifications are required for downstream flood
mitigation, easements or right-of-entry agreements will need to be obtained.
The developer will provide all supporting calculations and/or documentation to show that the
existing downstream conveyance system has capacity (Qf) to safely pass the fully-developed flood
mitigation storm discharge.
Option 1: Provide or Document Adequate Downstream Conveyance Systems
When the downstream receiving system does not have adequate capacity, then the developer
shall provide modifications to the off-site, downstream conveyance system. If this option is
chosen, the proposed modifications must be designed to adequately convey the full build-out
stormwater peak discharges for the “Flood Mitigation” storm event. The modifications must also
extend to the point at which the discharge from the proposed development no longer has an
impact on the receiving stream or storm drainage system.
The developer must provide supporting calculations and/or documentation that the
downstream peak discharges are safely conveyed by the proposed system, without endangering
downstream properties, structures, bridges, roadways, or other facilities, and no increase in
water surface elevation.
Option 2: Install Stormwater Controls to Maintain Existing Downstream Conditions
When the downstream receiving system does not have adequate capacity, then the developer
shall provide stormwater controls to reduce downstream flood impacts. These controls include
on-site controls such as detention, regional controls, and, as a last resort, local flood protection
such as levees, floodwalls, floodproofing, etc.
The developer must provide supporting calculations and/or documentation for each existing
discharge point indicating that the controls will be designed and constructed so that there is no
increase in downstream peak discharges or water surface elevations due to development.
Option 3: In lieu of a Downstream Assessment, Maintain Existing On-Site Runoff Conditions
Lastly with Option 3, on-site controls shall be used to maintain the pre-development peak
discharges for each existing discharge point from the site. The developer must provide
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Introduction
Design Criteria Manuals 34
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supporting calculations and/or documentation that the on-site controls will be designed and
constructed to maintain on-site existing conditions.
It is important to note that Option 3 may not require a downstream assessment. It is a detention-
based approach to addressing downstream flood mitigation after the application of the
integrated site design practices. However, a downstream assessment may b e required for sites
adjacent to or near streams in which delayed release of flows from detention facilities could
potentially increase the peak flow in the stream due to coincident peaks. This assessment of the
impact of coincident peaks is required for all sites with a contributing drainage area greater than
or equal to 10% of the stream drainage area at the subject discharge point.
4.6 Stormwater System Design
4.6.1 Introduction
Stormwater system design is an integral component of both site and overall stormwater management
design. Good drainage design must strive to maintain compatibility and minimize interference with existing
drainage patterns; control flooding of property, structures, and roadways for design flood events; and
minimize the potential environmental impacts of stormwater runoff.
Stormwater collection systems must be designed to provide adequate surface drainage while at the same
time meeting other stormwater management goals such as water quality, streambank protection, habitat
protection, and flood mitigation. Fully developed watershed conditions shall be used for determining runoff
for the “Flood Mitigation” storm event.
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
A. Introduction
This section is intended to provide criteria and guidance for the design of on-site flood mitigation
system components including:
1. Street and roadway gutters;
2. Stormwater inlets;
3. Storm drainpipe systems; and
4. Parking lot sheet flow.
B. Streets and ROW
1. Design Criteria
a. Flow spread limits for curbed streets are shown in Table 4.6-A below.
b. Inverted crown sections are permitted only in alleys.
c. Street crowns shall be reduced for approximately 100 feet on each side of the valley
gutters. No valley gutters will be permitted across collectors or arterials.
d. For non-curbed streets the “Flood Mitigation” storm event shall be contained within
paralleling roadside ditches, within the public ROW (Figure 4. 1 below).
e. Roadside ditches shall be designed to carry the “Flood Mitigation” runoff below the
roadway elevation.
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
Design Criteria Manuals 35
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f. Streets or alleys adjacent to an open channel shall have the edge of the pavement
designed with a minimum elevation of one (1) foot above the “Flood Mitigation”
elevation or as directed by the City’s Engineer.
g. Where additional hydraulic capacity is required on the street, the proposed street
gradient must be increased, or curb inlets and storm sewers installed to remove a
portion of the flow.
h. The maximum concentrated flow directed into the street (from a driveway or flume, etc.)
is three (3) cubic feet per second (cfs).
2. Flow Spread Limits
a. Inlets shall be spaced so that the spread of flow in the street for the “Flood Mitigation”
storm shall not exceed the guidelines listed below in Table 4.6-A, as measured from the
gutter or face of the curb:
Table 4.6-A: Flow Spread Limits
Street Classification Allowable Encroachment
Collectors one travel lane remains open
Arterials one travel lane in each direction remains open
Residential Streets curb depth
b. The allowable drainage flow across street intersections for the “Flood Mitigation” storm
event shall be as shown in Table 4.6-B as follows:
Table 4.6-B: Permissible Flow Across Street Intersections
Street Classification Cross-Flow
Arterial Street (divided and undivided) None
Non-Residential Collector Street None
Residential Street and Residential Collector Gutter Flow of 2 inches or less
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
Design Criteria Manuals 36
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Figure 4.1 Water Spread Limits for Non-Curbed Roadways
3. Minimum Street or Alley Elevations
No lowering of the standard height of street crown shall be allowed for the purposes of
obtaining additional hydraulic capacity. Street crowns shall be in accordance with the City of
Denton Standard Details.
C. Drainage Related Minimum Elevations
1. For lots in the influence of a sag area and a positive overflow, the finished floor elevation
(FFE) will be at least one (1) foot above the sag area top of the curb, or one (1) foot above
the possible maximum pool elevation when the positive overflow is functioning, whichever
elevation is higher.
2. New and substantially improved structures within the floodplain or within 200 feet of the
floodplain or SFHA must have their finished floor elevated to the minimum building elevation
as defined in the City’s Chapter 30 Flood Prevention and Protection Ordinance.
3. In all other areas, the minimum FFE shall be a minimum of one (1) foot above the street curb,
edge of alley, or rear property line (at the midpoint of the lot), whichever is lower.
D. Storm Inlet Design
1. Permissible Types of Inlet
a. Drop Inlets (Y-inlet) – Drop inlets are sump inlets which are not located along the curb
line of a roadway.
b. Grate Inlets – The use of grate inlets is not allowed on public drainage systems unless
through an approved design deviation request. If allowed, the inlet opening shall be
designed twice as large as the calculated opening to compensate for clogging. Grate
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
Design Criteria Manuals 37
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inlets may be used on private systems.
c. Curb Inlets – Curb inlets may be located at roadway low points (sumps) or on grade at
such points as to meet the water spread limitations and cross-flow depth requirements.
Curb inlets may be one of the following:
i. Recessed curb inlet – Recessed curb inlets are curb inlets constructed such that the
front of the inlet is two (2) feet behind the normal face of curb and the depression
does not extend into the traffic lanes.
ii. Standard curb inlet – Standard curb inlets are curb inlets that are in line with the
roadway curb.
iii. Type 2 curb inlet – Type 2 curb inlets are standard curb inlets where the inlet box
is located underneath the outer roadway lane instead of behind the curb. They are
only to be utilized in situations where there is insufficient parkway area or an
encumbered parkway area for a standard curb inlet.
2. Design Criteria
a. Public curb inlet size shall be 10, 15, or 20 feet. Maximum length of inlet at any one (1)
curb location shall be 20 feet on each side of the street. Inlets will be placed only in
straight sections of curb and at least 5 feet from any curb return. Inlets required in cul-
de-sacs are the only exceptions to the straight curb section requirement. Curb inlets are
not allowed in intersection or curb returns.
b. Recessed inlets will be required on arterial and non-residential collector streets.
c. The maximum inlet opening shall be six (6) inches. Openings larger than six (6) inches
shall require approval through a design deviation request and shall contain a bar or
other form of restraint.
d. Inlets shall be located in the following locations:
i. At low points;
ii. Upstream of pavement crown transitions at intersections (or the developer may
identify flow patterns and depths to show these inlets are not needed); and
iii. Where street flow spread limits or permissible intersection depths are exceeded.
e. Where possible, inlets at intersections shall be located on the street with the lesser
classification or on alleys.
f. A bypass of no more than 10% of the inlet capacity will be allowed for the “Flood
Mitigation” storm event.
g. To prevent water flowing across the street for the “Flood Mitigation” storm event, water
flowing in gutters of arterials should be picked up prior to reaching super -elevated
sections.
h. In super-elevated sections of divided arterials, inlets placed against the center medians
shall have no gutter depressions. Interior gutter flow (flow along the median) shall be
intercepted at the point of superelevation transition to prevent street cross-flow.
i. At bridges with curbed approaches, water should be intercepted before flowing onto
the bridge to prevent icing during cold weather.
j. New inlets shall not be constructed within a sidewalk or other pedestrian path.
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
Design Criteria Manuals 38
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k. The use of recessed inlets shall only be allowed where they do not adversely impact the
access or functionality of existing utility facilities.
l. Design and location of inlets shall take into consideration pedestrian and bicycle traffic.
m. The use of slotted drains is discouraged except in instances where there is no alternative.
Any use of slotted drains requires approval through a design deviation request. If used,
the manufacturer’s design guidelines should be followed.
n. Depressed inlets are recommended on continuous grades that exceed 1%, although
their use in traffic lanes should be avoided whenever possible.
o. A redundant, flanking inlet is required wherever a sag point or low point inlet is
identified, and no positive overflow path is provided. The redundant inlet shall have the
same size as the sag or low point inlet but will not be considered in the hydraulic
capacity calculations. The redundant inlet shall have a maximum inlet elevation of six (6)
inches above the sag or low point inlet elevation to ensure ponding does not overtop
the curb.
3. Inlet Computations
a. Sump Inlets and Drop Inlets
Curb inlets and drop inlets in a sump or low point can be considered to function as a
rectangular broad-crested weir with a coefficient of discharge of 3.06. The capacity shall
be based on the following weir equation:
Q / L or Q / P = 3.06 H3/2 [Eqn. 4.1]
Where: Q = Capacity of curb opening inlet or capacity of drop inlet (cfs)
H = Head at the inlet (feet)
L = Length of curb opening inlet (feet); or
P = Length of portion of perimeter of inlet opening, through which
water enters the drop inlet (feet)
Inlets should be located such that the inlet openings do not become submerged. In
some cases where this is not possible and the inlet operates under completely
submerged conditions, the orifice equation [Eqn. 4.2] should be used to compute the
inlet capacity, rather than the weir formula [Eqn. 4.1]. The capacity of a completely
submerged inlet shall be based on the following orifice equation:
Q = 4.84 A H1/2 [Eqn. 4.2]
Where: A = Area of inlet opening
The curves shown in Figure 4.2 and Figure 4.3 provide for direct solution of the above
equations.
In order to facilitate the computations required in determining the various hydraulic
properties for curb inlets and drop inlets in sump conditions, Figure 4.4 Computation
Sheet has been prepared.
Column 1 Inlet number and designation.
Column 2 Total flow in cfs to inlet. For inlets other than the first inlet in a system,
flow is the sum of runoff from the contributing area plus carry-over
flow from inlet or inlets upstream.
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
Design Criteria Manuals 39
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Column 3 Assumed length of inlet opening or perimeter in feet.
Column 4 Total area of inlet opening based on assumed inlet opening length
and opening height.
Column 5 Discharge per unit foot of inlet opening. Column 2 divided by Column
3.
Column 6 Computed head at inlet for weir flow conditions based on Figures 4.2
or 4.3 or the following equation:
H = (q / 3)2/3 [Eqn. 4.3]
Column 7 Computed head at inlet for orifice flow conditions (submerged inlet)
based on Figures 4.2 or 4.3 or the following equation:
H = [(Q / A) / 4.82]2 [Eqn. 4.4]
Column 8 Maximum allowable head at sump inlet. This value is determined from
topographic conditions at the sump inlet site.
Column 9 Width of spread of water for curb inlets in sump.
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
Design Criteria Manuals 40
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Figure 4.2 Capacity of Grate Inlet in Sump
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
Design Criteria Manuals 41
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Figure 4.3 Capacity of Drop Inlets and Curb Inlets in Sumps
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
Design Criteria Manuals 42
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Figure 4.4 Computation Sheet for Curb Inlets and Drop Inlets in Sumps
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
Design Criteria Manuals 43
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b. Inlets on Grade
The capacity of a curb inlet on grade will be based on the following equation:
Q / Lo = 0.7 [1 / yo] [(H)5/2 - (a)5/2] [Eqn. 4.5]
Where: Q = Discharge into inlet (cfs)
Lo = Length of inlet opening (feet)
a = Gutter depression (feet)
yo = Depth of flow in approach gutter (feet)
H = a + yo
The curve shown in Figure 4.6 provides for the direct solution of the above equation
when the value of yo is known. The curve shown in Figure 4.7 provides for the
determination of the ratio of the intercepted flow by the inlet to the total flow in the
gutter.
In order to facilitate the computations required in determining the various hydraulic
properties for curb inlets on grade, Figure 4.5 shows Computation Sheet prepared.
Column 1 Inlet Type and number.
Column 2 Location of inlet by station number.
Column 3 Drainage Area designation of area entering between the previous pick
up point and the inlet being designed.
Column 4 Peak Discharge (Qp) from area of Column 3.
Column 5 Carry-over flow (q) which has been passed by the last preceding inlet
to the inlet under consideration.
Column 6 Total gutter flow (Qo) in cfs. For inlets other than the first inlet in the
system, total gutter flow is the sum of the runoff from the contributing
area plus carry-over flow from the inlet or inlets upstream. Column 4
plus Column 5.
Column 7 Reciprocal of the pavement cross slope for pavements with straight
crown slopes.
Column 8 Reciprocal of the pavement cross slope (Z) divided by the pavement
roughness coefficient (n).
Column 9 Slope of approach gutter (So) in feet per feet.
Column 10 Depth of gutter flow "yo" in approach gutter direct from Manning’s
equation for triangular gutters:
yo = 1.245 (Q 3/8)[n3/8/ S3/16] [1 / Z]3/8 [Eqn. 4.6]
Column 11 Spread of water (Sp) or width of ponding in the gutter measured from
the face of curb. Column 7 times Column 10.
Column 12 Width of street and height of parabolic crown.
Column 13 Slope of approach gutter (So) in feet per feet.
Column 14 Depth of gutter flow " yo " in approach gutter.
Column 15 Spread of water (Sp) or width of ponding in the gutter
measured from face of curb.
Column 16 Discharge (Q) in cfs which will be intercepted by an inlet one (1) foot
in length for a given depth of flow in the approach gutter (yo).
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
Design Criteria Manuals 44
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Determined from Figure 4.6 or from the solution of the following
equation:
Q / Lo = 0.7 [1 / yo] [(H)5/2 - (a)5/2] [Eqn. 4.7]
Column 17 Length of inlet (Lo) in feet which is necessary to intercept a given
discharge Qo. Column 6 divided by Column 16.
Column 18 Actual length (L) in feet of inlet which is to be provided.
Column 19 Ratio of the length of inlet provided (L), to the length of the inlet
required for 100% interception (Lo). Column 18 divided by Column 17.
Column 20 Percentage of discharge intercepted by the inlet in question
determined from Figure 4.7 using the values determined in Column 19
and Column 10 or Column 14.
Column 21 Discharge (Q) in cfs which the inlet in question actually intercepts.
Column 6 times Column 20.
Column 22 Carry-over flow (q) is the amount of water which passes any inlet, and
is the difference between the total flow (Qo) of Column 6 and the
intercepted flow (Q) of Column 21.
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
Design Criteria Manuals 45
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Figure 4.5 Computation Sheet for Curb Inlets On Grade
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
Design Criteria Manuals 46
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Figure 4.6 Capacity for Inlets On Grade
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
Design Criteria Manuals 47
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Figure 4.7 Ratio of Intercepted Flow to Total Flow for Inlet On Grade
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.2 Hydraulic Design Criteria for Streets and Closed Conduits
Design Criteria Manuals 48
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E. Storm Drain Pipe Design
1. Design Frequency
Pipe Design: “Flood Mitigation” storm event.
2. Design Criteria
a. Storm drain systems capable of conveying the “Flood Mitigation” storm event are
required when water spread, intersection cross-flow, and lot-to-lot drainage flow limits
are exceeded, or when the minimum time of concentration shown in Table 1.5 of the
iSWM™ Hydrology Technical Manual Document are reached. Closed pipe systems are
required for discharges up to and including 300 cfs in public systems.
b. Pipe material in a public storm drain system or in public ROW shall be reinforced
concrete for all pipe sizes, or Polypropylene for sizes up to 60 inches, with appropriate
bedding and class type depending on cover.
c. Proposed storm drains may discharge into existing watercourses. See Section 1.2.10 of
the iSWM™ Hydraulics Technical Manual Document for guidance related to the Tailwater
elevation to be used for hydraulic grade line calculations.
d. The maximum hydraulic gradient shall not produce a velocity that exceeds 15 fps. Table
4.6-C shows the desirable velocities for most storm drainage design. Storm drains shall
be designed to have a minimum mean velocity flowing full at 2.5 fps.
Table 4.6-C: Desirable Velocity in Storm Drains
Description Max. Desirable Velocity (fps)
Culverts (All types) 15
Inlet laterals No Limit
Collectors (≤ 24 inches) 15
Mains (> 24 inches) 12
e. The minimum desirable physical slope shall be 0.5% or the slope that will produce a
velocity of 2.5 fps as required for the “Streambank Protection” storm event when the
culvert is flowing partially full, whichever is greater.
f. The potential hydraulic grade line elevation shall not exceed ground elevation or the
gutter flow line, whichever is lowest.
g. Access junction boxes are required along straight runs of closed conduits, with a
maximum spacing of 500 feet for all pipe and box sizes.
h. A minimum of 24 inches of vertical separation shall be maintained between storm sewer
conduits and any other utility. If it is not possible to provide 24 inches of vertical
separation, the design must be approved through a design deviation request and shall
not provide separation less than 6 inches and must provide a concrete cap between the
crossing utility line.
i. Junction Boxes shall also be located at:
i. any point where three (3) or more drainage conduits (laterals or trunk lines) come
together;
ii. any point where a trunk line size changes;
iii. grade changes;
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.3 Open Channels
Design Criteria Manuals 49
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iv. the upstream end of the storm drain system;
v. Bends greater than 45 degrees;
vi. Pipe junctions greater than 45 degrees; and
vii. At the connection point between public and private storm sewer pipes or boxes. If
this connection point is in the public ROW, pipe materials on the private system
must meet public storm drain system materials requirements. If the connection
point is on private property, then the public portion of the system must be
contained in an easement.
j. Inlets will not be allowed to serve as a junction box, except through an approved design
deviation request. Where inlets are permitted to serve as a junction box, the width of
the inlet, at a minimum, shall be doubled in size. Storm drain systems parallel to the
street will not be permitted to run directly through inlets.
k. Bends without junction boxes shall be limited to 45 degrees or less.
l. The minimum storm drain pipe diameter shall be 18 inches.
m. Pipe diameters shall not decrease downstream.
n. Laterals shall be connected to trunk lines using a junction box or manufactured wye
connections. Cut-in or punch-in connections to pipes are prohibited.
o. All cut-in or punch-in connections to precast inlets, junction boxes, box culverts, etc. will
require a concrete collar to be poured around the connection.
p. Vertical or horizontal curves/deflections in the conduit will not be permitted.
F. Parking Lot Design
Parking lots shall be designed for the “Flood Mitigation” storm not to exceed top of curb with a
maximum depth at low points of one (1) foot. The “Flood Mitigation” storm shall be contained on-
site or within dedicated easements. The portion of the parking lot detaining water during the “Flood
Mitigation” storm may be considered as part of the detention calculation for the site.
4.6.3 Open Channels
A. Design Frequency
1. Open channels, including all natural or improved channels, swales, and ditches shall be
designed for the “Flood Mitigation” storm event.
B. Design Criteria
1. Depending on velocities (See Table 4.6-E), constructed or improved channels shall be
designed with either an earthen channel or a 10-ft. minimum concrete pilot channel section
and appropriate side slope protection up to the “Streambank Protection” storm event
elevation, as described in Section 4.3.
2. All channels with contributing drainage basins larger than one (1) square mile (sq. mi.) shall
remain in their natural condition.
3. Channels with a contributing drainage area of less than one (1) sq. mi. shall remain in their
natural condition if they are identified as being within an ESA by the current City of Denton
ESA map. Channels not identified as being within an ESA may be channelized, with the
channelization method being determined by analysis of the erosive velocities.
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.3 Open Channels
Design Criteria Manuals 50
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4. All improved channels shall be designed to carry the flood mitigation flow and shall have
one (1) foot of freeboard as illustrated in Figure 4.8. Freeboard requirements at bends in all
improved channels shall be the greater of the following:
a. One (1) foot; or
b. 10% of the flow depth
5. At a minimum, channels that require concrete lining shall be lined up to an elevation of the
water surface resulting from the “Flood Mitigation” storm event.
6. Concrete lining of a stream channel is adding fill material into Waters of the United States
(WOTUS) and must comply with Section 404 of the Clean Water Act, and all requirements
outlined in DDC Section 7.4. Provide either proof of mitigation or letter of permission from
the United States Army Corps of Engineers (USACE).
7. Unlined improved channels that contain bends may be required to be armored if maximum
permissible velocities are exceeded.
8. Unlined improved channels shall have side slopes no steeper than 4H:1V and concrete-lined
channels shall have side slopes no steeper than 2H:1V.
9. The minimum grade allowed on any channel, outfall channel, or ditch shall be three-tenths
(3/10) foot per 100 feet for concrete-lined channels and five-tenths (5/10) foot per 100 feet
for grass-lined channels.
10. Geotechnical investigations will be required for open channel designs to determine the type
of soils present and allowable velocities shown in Table 4.6-D and Table 4.6-E.
11. For vegetative channels, flow velocities within the channel shall not exceed the maximum
permissible velocities given in Table 4.6-D and Table 4.6-E.
12. An evaluation of streambank stabilization shall be included in the design of open channel
improvements for areas upstream and downstream of the proposed improvement. Where
indicated by the analysis, stabilization of the offsite bank areas shall be included in the
proposed design.
13. HEC-RAS, or similarly capable software approved by the City’s Engineer, shall be used to
confirm the water surface profiles in open channels.
14. The final design of artificial open channels shall be consistent with the velocity limitations for
the selected channel lining. Maximum velocity values for selected lining categories are
presented in Table 4.6-D below.
15. If relocation of a stream channel is unavoidable, fill material into WOTUS must comply with
Section 404 of the Clean Water Act, and all requirements outlined in DDC Section 7.4. Provide
either proof of mitigation or letter of permission from the United States Army Corps of
Engineers (USACE).
The design of stable rock riprap lining depends on the intersection of the velocity (local boundary
shear) and the size and gradation of the riprap material. More information on calculating acceptable
riprap velocity limits is available in Section 3.2.7 of the iSWM™ Hydraulics Technical Manual
Document.
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.3 Open Channels
Design Criteria Manuals 51
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Table 4.6-D: Roughness Coefficients (Manning’s n) and
Allowable Velocities for Natural Channels
Channel Description Manning’s
n
Max. Permissible
Channel Velocity
(fps)
MINOR NATURAL STREAMS
Fairly regular section
1. Some grass weeds 0.030 3 to 6
2. Dense growth of weeds, depth of flow materially greater than weed height 0.035 3 to 6
3. Some weeds, light brush on banks 0.035 3 to 6
4. Some weeds, heavy brush on banks 0.050 3 to 6
5. Some weeds, dense willows on banks 0.060 3 to 6
- For trees within channels with branches submerged at high stage, increase values by 0.010
- Irregular section with pools, slight channel meander, increase above values by 0.010
Floodplain - Pasture
1. Short grass 0.030 3 to 6
2. Tall grass 0.035 3 to 6
Floodplain – Cultivated Areas
1. No crop 0.030 3 to 6
2. Mature row crops 0.035 3 to 6
3. Mature field crops 0.040 3 to 6
Floodplain – Uncleared
1. Heavy weeds scattered brush 0.050 3 to 6
2. Wooded 0.120 3 to 6
MAJOR NATURAL STREAMS
Roughness coefficient is usually less than for minor streams of similar description on
account of less effective resistance offered by irregular banks or vegetation on banks.
Values of ‘n’ for larger streams of mostly regular sections , with no boulders or brush
0.028 to
0.060 3 to 6
UNLINED VEGETATED CHANNELS
Clays (Bermuda Glass) 0.035 5 to 6
Sandy and Silty Soils (Bermuda Glass) 0.035 3 to 5
UNLINED NON-VEGETATED CHANNELS
Sandy Soils 0.030 1.5 to 2.5
Silts 0.030 0.7 to 1.5
Sandy Silts 0.030 2.5 to 3.0
Clays 0.030 3.0 to 5.0
Coarse Gravels 0.030 5.0 to 6.0
Shale 0.030 6.0 to 10.0
Rock 0.025 15
Notes:
[1] For natural channels with specific vegetation type, refer to Table 4.6-E for more detailed velocity control.
Section 4: Stormwater Design Criteria
4.6 Stormwater System Design
4.6.3 Open Channels
Design Criteria Manuals 52
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Table 4.6-E: Maximum Velocities for Vegetative Channel Linings
Vegetation Type Slope Range 1
(%)
Max. Velocity 2
(fps)
Bermuda Grass 0 – 5 6
Bahia - 4
Tall fescue grass mixtures 3 0 – 10 4
Kentucky bluegrass 0 – 5 6
Buffalo grass 4 5 – 10
> 10
5
4
Grass mixture 4 0 – 5
5 – 10
4
3
Sericea lespedeza, Weeping lovegrass, Alfalfa 0 – 5 3
Annuals 5 0 – 5 3
Sod - 4
Lapped Sod - 5
Notes:
[1] Do not use on slopes steeper than 10% except for side-slope in combination channel.
[2] Use velocities exceeding 5 fps only where good stands can be maintained.
[3] Mixtures of Tall Fescue, Bahia, and/or Bermuda.
[4] Buffalo Grass and Grass Mixture will be required over other vegetation types where the maximum velocity is not exceeded.
[5] Annuals – used on mild slopes or as temporary protection until permanent covers are established.
Source: Manual for Erosion and Sediment Control in Georgia, 1996.
Figure 4.8 Freeboard Requirements and Channel Section Illustrations
Section 4: Stormwater Design Criteria
4.7 Culverts
4.7.2 Design Frequency
Design Criteria Manuals 53
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C. Channel Drop Structures
1. Sloping channel drops are permitted and are required to have a maximum slope of 4H:1V.
Vertical channel drops are not permitted.
2. The flow velocities in the channel upstream and downstream of the drop structure need to
satisfy the permissible velocities allowed for channels (Table 4.6-D). The velocities shall be
checked for flows produced by the “Streambank Protection” and “Flood Mitigation” storm
events.
3. An apron shall be constructed immediately upstream of the chute or stilling basin to protect
against the increasing velocities and turbulence which result as the water approaches the
drop structure. The apron shall extend at least five (5) feet upstream of the point where flow
becomes supercritical. In no case shall the length of the upstream apron be less than 10 feet.
4. An apron shall be constructed immediately downstream of the chute or stilling basin to
protect against erosion due to the occurrence of the hydraulic jump. The apron shall extend
a minimum of 10 feet beyond the anticipated location of the jump.
5. The design of drop structures is based on the height of the drop, the normal depths upstream
and downstream of the drop structure, and discharge.
6. When used, channel drop structures shall be located near bridges or culverts, as directed by
the City’s Engineer.
7. The location of the hydraulic jump should be determined based on the upstream and
downstream flow depths, and channel slopes.
8. The length of the hydraulic jump should be calculated to determine the length of the
downstream apron required to prevent erosion.
4.7 Culverts
Culverts are cross drainage facilities that transport runoff under roadways or other improved areas.
4.7.1 Design Frequency
A. Culverts shall be designed for the “Flood Mitigation” storm.
B. The “Flood Mitigation” storm shall be routed through all culverts to ensure building structures (e.g.,
houses, commercial buildings) are not flooded and damage does not occur to a highway or adjacent
property for this design event.
4.7.2 Design Criteria
A. Design Considerations
1. Roadway type;
2. Tailwater or depth of flow;
3. Structures, and property subject to flooding;
4. Emergency access; and
5. Road replacement costs.
Section 4: Stormwater Design Criteria
4.7 Culverts
4.7.3 Driveway Culverts
Design Criteria Manuals 54
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B. Velocity Limitations
1. The maximum velocity shall be consistent with channel stability requirements at the culvert
outlet.
2. The maximum allowable velocity is 15 fps, but outlet protection shall be provided where
discharge velocities will cause erosion conditions.
3. To ensure self-cleaning during partial depth flow, a minimum velocity of 2.5 fps is required
for the “Streambank Protection” storm when the culvert is flowing partially full.
C. Headwater Limitations
1. The allowable headwater is the depth of water that can be ponded at the upstream end of
the culvert during the “Flood Mitigation” storm event. The allowable headwater will be limited
by both of the following constraints or conditions:
a. The headwater must not damage upstream property.
b. The culvert headwater plus 12 inches of freeboard shall not exceed (i) top of curb or (ii)
pavement for the low point of the road over the culvert, whichever is lower.
D. Tailwater Considerations
1. If the culvert outlet is operating with a free outfall, the critical depth and equivalent hydraulic
grade line shall be determined.
2. For culverts that discharge to an open channel, the stage-discharge curve for the channel
must be determined. See Section 2.1.4 of the iSWM™ Hydraulics Technical Manual on
methods to determine a stage-discharge curve.
3. If an upstream culvert outlet is located near a downstream culvert inlet, the headwater
elevation of the downstream culvert will establish the design tailwater depth for the upstream
culvert.
4. If the culvert discharges to a lake, pond, or other major water body, the expected “Flood
Mitigation” storm event of the water body will establish the culvert tailwater.
E. Other Criteria
1. Culvert skews shall not exceed 30 degrees, as measured from a line perpendicular to the
roadway centerline, without approval.
2. Erosion, sediment control, and velocity dissipation shall be designed in accordance with
Section 4.0 of the iSWM™ Hydraulics Technical Manual Document.
3. Where applicable, culverts must comply with DDC Section 7.4 regarding Environmentally
Sensitive Areas.
4.7.3 Driveway Culverts
Driveway culverts are only permitted in non-curbed roadway sections. All driveway culvert construction shall
be inspected by the City during construction. All driveway culverts shall meet the following requirements:
A. All new driveway culverts must be designed to convey flows from a “Flood Mitigation” storm.
Replacement driveway culverts shall be designed to convey the maximum reasonable discharge
based on the existing ditch dimensions adjacent to the culvert.
B. Culverts shall have a minimum pipe diameter of 18 inches.
Section 4: Stormwater Design Criteria
4.8 Bridges
4.8.2 Design Frequency
Design Criteria Manuals 55
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C. Acceptable culvert material shall be Reinforced Concrete Pipe (RCP) with a diameter of 18 to 42
inches. The RCP must be designated Class III at a minimum.
D. Box culverts shall have a minimum height of 24 inches. Culverts under City streets used for
entrances to a subdivision shall be made of approved classes of reinforced concrete pipe or box.
E. The top of pipe elevation must be below the adjacent roadway edge of pavement elevation.
F. Pipe culverts shall utilize a safety end treatment conforming to the most current version of the
TxDOT standard detail Safety End Treatment Plan – Parallel Drainage (SETP-PD) with the slope of
the riprap being 6H:1V.
G. A driveway approach may utilize a low-water crossing in lieu of a driveway culvert, if all of the
following conditions are met:
1. The lowest elevation of the proposed crossing can be no more than eight (8) inches below
the road edge elevation.
2. The proposed low-water crossing cannot create a ponding effect on the upstream ditch (i.e.,
ditch flow line must be equal to or higher than the crossing).
3. Minimum cross slope for the crossing of 1.5%.
4. Low-water crossing shall be constructed of concrete adhering to the City of Denton Standard
Details.
5. Toe walls on each side of the crossing shall be extended at least 15 inches below grade to
prevent undercutting.
H. Culvert Slope requirements:
1. Culvert slope must provide positive drainage.
2. Culvert slope shall be set as shown on the approved subdivision construction plans.
3. Minimum slope shall be 0.3%.
I. Ditch Slope Requirements
1. The ditch shall be graded upstream and downstream as far as necessary to provide positive
drainage with no areas of standing water.
2. Minimum earthen slope is 0.5%.
3. Minimum concrete slope is 0.3% for 2-ft. concrete pilot channels, if 0.5% earthen slope is
unobtainable.
4.8 Bridges
4.8.1 Design Frequency
A. “Flood Mitigation” storm must be used for all bridges.
4.8.2 Design Criteria
A. A freeboard of two (2) feet shall be maintained between the computed design water surface and
the low chord of all bridges.
Section 4: Stormwater Design Criteria
4.9 Detention Facilities
4.9.2 Other Criteria
Design Criteria Manuals 56
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B. Design guidance is provided in Section 3.4 of the iSWM™ Hydraulics Technical Manual Document.
4.8.3 Other Criteria
A. Where applicable, bridges must comply with DDC Section 7.4 regarding Environmentally Sensitive
Areas.
4.9 Detention Facilities
4.9.1 Design Requirements
A. Detention facilities shall be designed for the four storms (“Water Quality”, “Streambank Protection”,
“Conveyance”, and “Flood Mitigation”) for the critical storm duration that results in the maximum
(or near maximum) peak flow.
B. Dry detention basins must be sized to temporarily store the volume of runoff required to provide
flood protection up to the “Flood Mitigation” storm.
C. Routing calculations must be used to demonstrate that the storage volume and outlet structure
configuration comply with Section 4.5.5 of this Manual.
D. A calculation summary shall be provided on construction plans as shown in the computation sheet
in Figure 4.9 or its equivalent. Stage-storage-discharge values shall be tabulated and flow
calculations for discharge structures shall be shown on the construction plans. Detention design
shall follow iSWM™ guidelines. It is the responsibility of the Engineer of Record to use appropriate
methodologies presented in iSWM™ based on specific basin characteristics. Detailed calculations
and a design narrative shall be provided for review in a supplemental report that is referenced on
the construction plans. In general, the narrative shall provide basic design information, such as the
hydrologic method applied, design assumptions, pre- and post-development site conditions,
downstream constraints, environmental considerations, and design software version used, if
applicable.
E. Storage and dam safety design may be subject to the requirements of the Texas Dam Safety
Program based on the volume, dam height, and level of hazard. Earthen embankments six (6) feet
in height or greater shall be designed per the TCEQ guidelines for dam safety (See Texas
Administrative Code, Title 30, Part 1, Chapter 299 Dams and Reservoirs for current dam safety
criteria).
F. An Operation and Maintenance Manual must be submitted with the civil engineering plans for all
private detention basins. Private detention basins shall be inspected by Public Works Inspection to
ensure compliance with the design standards required by Section 7.5.3.F. of the DDC. Inspection
fees will apply.
4.9.2 Design Criteria for Above Grade Detention Facilities
A. Grading Standards for Above Grade Detention Facilities:
1. Vegetated channel slopes shall not exceed 4H:1V slope. Concrete-lined embankment slopes
shall not exceed 2H:1V slope. Vertical walls may be allowed but must be structurally designed
to account for inundation of the base and drawdown upon pond draining and must have a
6-ft. high security fence at the top.
Section 4: Stormwater Design Criteria
4.9 Detention Facilities
4.9.2 Design Criteria for Above Grade Detention Facilities
Design Criteria Manuals 57
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2. The side slope for any excavated detention basin, which is not in rock, shall not exceed a
4H:1V slope.
3. Bottom slopes of detention facilities should not be less than 1%.
4. Armored slopes shall be no steeper than 2H:1V.
5. The embankment crown width shall be determined based on a geotechnical investigation of
the detention facility site. The minimum width of the embankment crown shall be 12 feet.
6. Earthen embankments used to impound detention water must have a non-permeable core
and shall be based on a geotechnical investigation of the site. The geotechnical investigation
shall be performed by a Professional Engineer (PE), licensed by the State of Texas, and shall
include at a minimum the type of material on-site (or other material to be used in the
embankment), moisture content, liquid limit, plasticity index, and required compaction.
7. A Concrete pilot channel with a minimum width of 10 feet, and a minimum slope of 0.5%
shall be constructed at the bottom of the detention pond. Privately maintained ponds shall
have a concrete pilot channel with a minimum width of six (6) feet.
8. Private Detention Basins shall be designed with 10-ft. wide unobstructed maintenance access
around the entire perimeter of the pond.
9. Public Detention Basins shall be designed with 20-ft. wide unobstructed maintenance access
around the entire perimeter of the pond.
10. Where deemed necessary by the City’s Engineer, security fencing with a minimum height of
six (6) feet shall encompass the detention storage area if the velocity, depth, or slopes create
a potentially dangerous condition. The fence shall be designed to allow access for
maintenance and so as not to restrict stormwater flow into or out of the detention basin. A
maintenance equipment access ramp shall be provided for all detention facilities. The slope
of the ramp shall not exceed 6H:1V and the minimum width shall be 12 feet.
B. Emergency Spillway, Overflow Path, and Freeboard:
1. A freeboard of one (1) foot will be required between the “Flood Mitigation” stormwater
surface elevation and top of bank.
2. An emergency spillway shall be provided at the flood mitigation maximum storage elevation
with sufficient capacity to convey “Flood Mitigation” storm inflow rates with six (6) inches of
freeboard. This is the peak of the inflow hydrograph coming into the pond and must not
account for attenuation effects of the pond. Spillway requirements must also meet all
appropriate State and Federal criteria.
3. An emergency overflow path, free of structures or obstructions, must be provided to convey
the spillway design discharge to a downstream ROW or drainageway with adequate capacity
for the discharge. No impediments to flow are allowed within the emergency overflow path
(E.g., fences, trees, parking areas, or buildings). If a fence around a detention facility is needed
to restrict access, the bottom of the fence must be elevated to provide a minimum of one
foot of freeboard above the emergency overflow WSEL where the fence crosses the spillway.
Nevertheless, fences across spillways should be avoided whenever possible. Even if the fence
is elevated to the freeboard elevation, there is still the potential for the fence to catch debris
floating on the water surface.
4. An emergency spillway must be constructed of concrete.
Section 4: Stormwater Design Criteria
4.9 Detention Facilities
4.9.3 Design Criteria for Underground Detention Facilities
Design Criteria Manuals 58
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5. Design calculations shall be provided for all spillways and outlet structures.
C. Landscaping Requirements:
1. All detention basins shall be designed with plantings that minimize erosion based on
expected inundation frequencies. Design guidance is provided in the iSWM™ Landscape
Technical Manual Document.
D. Multiple Use Guidance
Limited recreational equipment (such as picnic tables or playground equipment) and trees may be
permitted in private detention facilities with the following restrictions:
1. User access must be provided at a maximum 10% slope in at least two (2) locations, or one
(1) location that comprises not less than 20% of the perimeter of the facility.
2. No recreational equipment is permitted in any portion of the facility that lies more than 18
inches below the flood mitigation water surface elevation level of the facility.
3. Recreational structures including, but not limited to, picnic tables and playground
equipment, must be rust-resistant and anchored to the ground.
4. Mulch, wood chips, gravel, or rubberized pellets are not permitted within a detention facility
due to the likelihood of their floating into the outlet structure.
5. Trees, shrubs, and other woody vegetation will not be permitted in the embankment of any
detention facility or in the maintenance access area around such a facility.
6. A maximum of one (1) isolated tree per 5,600 sq. ft. may be permitted in the recreational
area of the pond. A trash rack must be used to prevent clogging of the outlet structure. No
bark mulch may be used around trees.
E. Retaining Walls
1. Any freestanding retaining wall used to detain water must be designed by a structural
engineer to withstand the expected hydraulic forces when the detention area is filled to
capacity. These walls must be constructed using reinforced concrete.
2. Any inlet or pipe connections to retaining walls must be designed with a reinforced concrete
headwall. The height of this headwall shall match the height of the adjacent retaining wall.
The most recent TxDOT details for concrete headwalls shall be used to determine other
headwall dimensions and reinforced schedule.
4.9.3 Design Criteria for Underground Detention Facilities
Underground detention is highly discouraged because of the potential for deferred maintenance, the
difficult and potentially hazardous nature of access for maintenance, and issues related to anaerobic
conditions and pollutant mobility from devices that retain water between events. In any instance where
underground detention is contemplated, thorough consideration must be given to the concerns described
above to ensure ongoing inspection, maintenance, and functionality. Care should be taken to address
material selection for underground detention due to the potential for adverse soil conditions to inhibit the
system from functioning properly. A geotechnical engineer shall be consulted to ensure soil and other
conditions are appropriate for the selected detention material.
A. Underground detention facilities shall be designed with reinforced concrete and have a minimum
pipe diameter of 30 inches to allow for safe access and maintenance of the facility.
Section 4: Stormwater Design Criteria
4.9 Detention Facilities
4.9.4 Design Criteria for Parking Lot Detention
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B. If an underground vault has multiple chambers, access openings with a maximum spacing of 500
feet must be provided for each chamber.
C. Underground facilities must be located to enable safe access for maintenance and minimize
disruption of aboveground uses during maintenance. Access openings shall not be placed in areas
that are routinely used for parking.
D. Easements must be provided for all underground detention facilities. If underground detention
facilities are bound by private property, the easements must include an additional four (4) feet from
the perimeter of the facilities.
E. Underground detention and water quality facilities are prohibited underneath buildings, walls, or
other structures.
F. Every SWFMA involving underground detention and water quality facilities must include inspection
and maintenance requirements to be performed quarterly and following any rainfall event of 0.5
inches or more. The inspection and maintenance frequency may be reduced after five (5) years of
operation, if the owner demonstrates that a lesser frequency is appropriate.
G. A surface emergency overflow path, free of obstructions, must be provided for all underground
detention facilities. The emergency overflow path must have sufficient capacity to convey the “Flood
Mitigation” storm inflow rates to the underground detention facility. This is the peak of the inflow
hydrograph coming into the underground detention facility, and must not account for any
attenuation effects from the facility. The criteria for emergency overflow paths for surface detention
facilities denoted in Section 4.9.2 above also apply to underground detention facilities.
H. Outlets from underground detention must consist of a pipe that can convey 120% of the 100 -year
outflow, with a minimum diameter of 12 inches. The invert of the outlet pipe must be at the lowest
point in the detention facility to ensure that it fully drains.
I. Underground detention facilities shall be sloped to drain at a minimum floor slope of one (1) %.
4.9.4 Design Criteria for Parking Lot Detention
Parking lot detention may be allowed if the following minimum criteria are met:
A. Use of parking lot surface area as detention is permitted, but only up to the lowest curb elevation
of the parking lot.
B. The maximum ponding depth for the 100-year storm must be no more than 12 inches at the
deepest point.
C. The outlet must be designed to minimize modifications that affect detention functions. The
applicant must evaluate potential future resurfacing activities for impacts to detention volumes and
release rates.
D. Ponding water in frequently used portions of parking lots must be avoided. At least two signs are
required for all parking lot detention areas. The signs must have a minimum area of 1.5 sq . ft. and
contain the following message:
WARNING
This area is a detention basin and is subject to periodic
flooding to a depth of (provide design depth).
Section 4: Stormwater Design Criteria
4.9 Detention Facilities
4.9.6 Design Criteria for Pumped Detention
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Sign materials, geometry, and location must be submitted to Development Facilitation and
approved by the City’s Engineer.
4.9.5 Design Criteria for Pumped Detention
A. A detention facility may not rely on a pump or other mechanical equipment to drain water during
a design storm.
4.9.6 Outlet Structures for Detention Facilities
A. Design Frequency
1. “Water Quality” storm
2. “Streambank Protection” storm
3. “Conveyance” storm
4. “Flood Mitigation” storm
B. Design Criteria
1. Outlet structures shall be designed in accordance with Section 2.2 of the iSWMTM Hydraulics
Technical Manual. For water quality, refer to Section 2.2.3 for design of extended detention
outlets.
2. The required storage volumes for “Water Quality”, “Streambank Protection”, “Conveyance”,
and “Flood Mitigation” storm events must be estimated.
3. If a detention facility includes extended detention, refer to Section 2.2.3 of the iSWMTM
Hydraulics Technical Manual for design requirements.
4. All outlet orifices must be adequately protected from clogging and designed to ensure that
people and large animals are kept out of confined outlet areas. Refer to Sections 2.2.5-
Extended Detention Outlet Protection and 2.2.6-Trash Racks and Safety Grates of the iSWMTM
Hydraulics Technical Manual for design guidance.
5. Any top orifice on an outlet riser must be designed with a grate to prevent fall injuries.
6. Outlet velocities shall be within the maximum allowable range based on channel material, as
shown in Table 4.6-D and Table 4.6-E.
7. Outlet protection and energy dissipation facilities must be designed to avoid erosion
problems downstream from outlet devices and emergency spillway(s).
8. Buoyancy calculations must be performed for the outlet structure and footing to ensure the
outlet structure will not float. Flotation will occur when the weight of the structure is less
than or equal to the buoyant force exerted by the water.
9. Any outflow structure that conveys water through an embankment in a conduit shall be
reinforced concrete designed to support the external loads. The conduit shall be able to
withstand the internal hydraulic pressure without leakage under full external load or
settlement and must convey water at the design velocity without damage to the interior
surface of the conduit.
10. The minimum opening of an inlet shall be six (6) inches in diameter or a 6-in. by 6-in. square.
Smaller inlet openings may be used with a junction box and properly sized outlet structure.
Section 4: Stormwater Design Criteria
4.9 Detention Facilities
4.9.6 Outlet Structures for Detention Facilities
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11. A concrete headwall and wingwalls shall be constructed at the outlet pipe opening.
Orientation of the wingwalls will be governed by site specific conditions. Headwalls and
wingwalls shall be designed to TxDOT standards.
Section 4: Stormwater Design Criteria
4.9 Detention Facilities
4.9.6 Outlet Structures for Detention Facilities
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Figure 4.9 Computation Sheet for Detention Pond Design
Section 4: Stormwater Design Criteria
4.10 Energy Dissipation
4.11.1 Design Frequency
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4.10 Energy Dissipation
All drainage system outlets, whether for closed conduits, culverts, bridges, open channels, or storage
facilities, shall provide energy dissipation when necessary to protect the receiving drainage element from
erosion.
4.10.1 Design Frequency
A. “Flood Mitigation” storm
4.10.2 Design Criteria
A. Erosion problems at culvert, pipe and engineered channel outlets are common. Determination of
the flow conditions, scour potential, and channel erosion resistance shall be standard procedure for
all designs.
B. Energy dissipaters shall be employed whenever the velocity of flows leaving a stormwater
management facility exceeds the erosion velocity of the downstream area channel system.
C. Energy dissipater designs will vary based on discharge specifics and tailwater conditions.
D. Outlet structures shall provide uniform redistribution or spreading of the flow without excessive
separation and turbulence.
4.10.3 Recommended Energy Dissipater for outlet protection
A. Concrete or grouted rock riprap apron
B. Riprap outlet basins
C. Baffled outlets
D. Grade Control Structures
Design guidance is provided in Section 4.0 of the iSWMTM Hydraulics Technical Manual.
4.11 Floodplain
4.11.1 Floodplain Development Criteria
A. Floodplain alterations shall be allowed only if all the following criteria are met:
1. An approved Floodplain Development Permit must be issued by the City before any
development is done within the floodplain.
2. Flood studies shall include flows generated for existing conditions and fully-developed
conditions for the 10, 50, 100, and 500-year storm events.
3. Alterations shall not increase the 100-year fully-developed water surface elevation on other
properties.
4. Alterations to the regulatory Floodway shall not increase the 100-year fully-developed water
surface elevation at any point.
5. Alterations shall be in compliance with Federal Emergency Management Agency (FEMA)
guidelines.
Section 4: Stormwater Design Criteria
4.11 Floodplain
4.11.1 Floodplain Development Criteria
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6. Alterations of the floodplain shall meet the requirements of Section 4.5 of this Manual.
7. Alterations shall result in no loss of valley storage for a Major Creek, as defined by the DDC,
and a 15% maximum loss of valley storage for any other tributary for any reach, except at
bridge and culvert crossings where it can be proven that there are no detrimental effects
upstream or downstream.
8. Alteration of floodplain areas shall not cause any additional expense, including maintenance,
related to any current or projected public improvements.
9. The floodplain shall be altered only to the extent permitted by equal conveyance on both
sides of the natural channel, as defined by the USACE in a HEC-RAS analysis. The right of
equal conveyance applies to all owners and uses, including greenbelt, park areas, and
recreational areas. Owners may relinquish their right to equal conveyance by providing a
written agreement to the City’s Engineer.
10. A grading permit and/or construction plan approval shall be required to perform any grading
activities on site.
11. The toe of any fill shall parallel the natural direction of the flow.
12. Floodplain alterations shall incorporate and consider other City planning documents and
ordinances such as the Tree Preservation Ordinance (Section 7.7.4 – DDC), the Subdivision
Ordinance (Subchapter 8 – DDC), and the Floodplain Prevention and Protection Ordinance
(Chapter 30 – City of Denton, Code of Ordinances).
13. Unless a pre-existing model is in place, USACE’s HEC-HMS and HEC-RAS shall be used. A
request to use another type of hydrologic or hydraulic model must be submitted for approval
through a design deviation request. The Modified Puls method shall be used for flood
routing information to ensure that the cumulative effects of the reduction in floodplain
storage of floodwater will not cause downstream or upstream increases in water surface
elevations and erosive velocities. If the Modified Puls method is not feasible, a request to use
another type of flood routing method must be submitted for approval through a design
deviation request.
B. The engineer of record is responsible for providing documentation of the relevant USACE approved
permits prior to beginning modification of the floodplain and prior to causing any impacts to
WOTUS. If applicable, the engineer of record is also responsible for providing a signed and sealed
statement detailing why such permits are unnecessary.
C. Verification of Floodplain Alterations:
1. The owner and/or developer shall furnish, at their expense, to Development Services
sufficient engineering information to confirm that the minimum FFEs proposed meet the
requirements of the Flood Prevention Ordinance.
2. Construction plans will not be released for construction within areas subject to a Conditional
Letter of Map Revision (CLOMR) or amendment until such plans are accepted by
Development Services and FEMA.
3. Letters of Map Revision (LOMR) applications shall be submitted to Development Services (i)
no later than 60-days from the City’s final acceptance of the construction and (ii) prior to
submittal to FEMA.
4. All submittals to FEMA shall be submitted to Development Services prior to submittal to
Section 4: Stormwater Design Criteria
4.11 Floodplain
4.11.1 Floodplain Development Criteria
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FEMA. A copy of all responses to FEMA comments shall be submitted to the City.
D. Development within the floodplain which does not result in any change to the topography, the
amount or location of impervious area, or any change in the characteristics of the floodplain cross -
section, such as underground utility construction, may not require a flood study, CLOMR, LOMR, or
DSA unless requested by the City.
The following decision charts are intended to consolidate the floodplain development criteria in the City of
Denton. They reference information found in the DDC Subchapters 7.4 and 7.5, the Code of the City of
Denton, Texas, Chapter 30, and this Manual. They are not an exhaustive list of criteria and are only to be
used as guidance as to the information provided in the above-referenced documents. Criteria in those
documents supersedes the decision charts.
Figure 4.10 Flood Study Decision Chart
Section 4: Stormwater Design Criteria
4.11 Floodplain
4.11.1 Floodplain Development Criteria
Design Criteria Manuals 66
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Figure 4.11 Summarized Floodplain Development Procedure
Section 4: Stormwater Design Criteria
4.11 Floodplain
4.11.2 Procedures for Floodplain Alteration
Design Criteria Manuals 67
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4.11.2 Procedures for Floodplain Alteration
Floodplain development is permitted when it complies with all requirements of the DDC, Flood Prevention
Ordinance, and this Manual. The following are the engineering criteria for such requests.
Developments which impact designated FEMA flood plains in the City (Zones AE, A, and X shaded) shall
submit minimum data required by FEMA, indicated on the City’s CLOMR submittal checklist, and/or
indicated in this Manual to FEMA for conditional approval. The Conditional Letter of Map Revision (CLOMR)
shall be submitted to the City prior to approval of any Zoning Compliance Plan. Approval of CLOMR from
FEMA will be required prior to acceptance of Civil Engineering Plans.
A. A written description of the scope of the proposed project and the methodology used to analyze
the project’s effects.
B. Hydraulic backwater models for 10, 50, 100, and 500-year floods for the following:
1. Duplicate of the effective FIS model. The model must include:
a. Existing conditions (effective FIS model including cross-sections through the project
site. All cross-sections should reflect conditions prior to construction of the project); and
b. Proposed conditions (existing conditions model reflecting the proposed project).
C. Floodway hydraulic backwater models of the following:
1. Duplicate effective;
2. Existing condition; and
3. Proposed conditions.
D. In all the above hydraulic models, the following rules will apply:
1. The hydraulic parameters, such as bridge loss coefficients, “n” values, etc., used in the
effective FIS models will only be changed where obvious errors or changes have taken place
and must be documented;
2. The computed water surface elevation profiles must converge with the existing profiles; and
3. Information should be shown on a map of suitable scale and topographic definition to
provide reasonable accuracy.
E. A copy of the FIRM with the project area indicated.
F. Topographic mapping of the entire area covered by the proposed condition model, indicating the
locations of all cross-sections used in the hydraulic model and delineating the proposed 100-year
flood plain boundary.
G. Topographic mapping of the entire area covered by the proposed conditions model, indicating the
locations of all cross-sections used in the hydraulic model and delineating:
1. The proposed 100-year and 500-year floodplain boundaries; and
2. The proposed floodway boundary.
H. Projects must comply with the requirements of 44 C.F.R. § 60.3(d)(2).
I. Upon completion of the proposed project, “as-built” and final LOMR plans certified by a PE licensed
by the State of Texas shall be submitted to the City for review and subsequent transmittal to FEMA.
FEMA requires that individual legal notices be sent to all affected property owners when
development (cut or fill) occurs in the regulatory floodway that would cause any rise in the 100-
Section 4: Stormwater Design Criteria
4.11 Floodplain
4.11.4 Fully Developed Water Surface Elevation Calculations
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year FIS water surface elevation. Public notice in the official community newspaper is required for
proposed modifications to the regulatory floodway.
J. All items should be labeled for easy cross-referencing to the hydraulic model and summary data.
K. FEMA may have questions regarding the project. The engineer of record must address all of FEMA’s
comments. It is not anticipated, but if revisions to the development are required by FEMA, the
developer is responsible for making the changes.
4.11.3 Fully Developed Water Surface Elevation Calculations
A. The following hydraulic data should be submitted to the City, preferably using the USACE HEC-RAS
program to compute the channel’s water surface elevation. The data should be submitted
electronically as part of the CLOMR, LOMR, or flood study submittal.
1. Duplicate of the effective City fully developed backwater model or as developed by
developer or property owner and approved by the City.
2. Modified existing condition backwater model – this model should include pre-development
cross-sections through the project site obtained from field surveys or updated topographic
information.
3. Proposed condition reflecting the development’s impact on the flood plain area.
4. Water surface elevation and velocity summary tables tabulating the results of the above
analysis.
5. Topographic map at a suitable scale with cross-sections that delineates the existing and
proposed 1% chance (100-year) fully developed flood plain and shows the area being
developed.
6. Analysis of the existing and proposed valley storage conditions of the area.
7. Documentation from the USACE determining if a 404 permit is required for the project.
4.11.4 Floodplain Alteration Guidelines
A. Side Slopes
1. To ensure maximum accessibility to the floodplain for maintenance and other purposes, and
to lessen the probability of slope erosion during periods of high water, maximum slopes of
filled area shall usually not exceed 4H:1V. Grass cover is required for all cut and fill slopes
unless other armoring is required. Concrete riprap or an approved equal erosion protection
measure is required on slopes steeper than 4H:1V. Vertical walls, terracing and other slope
treatments will be considered only as:
a. Part of a landscaping plan submission, and
b. If no unbalancing of stream flow results.
B. Vegetation/Landscaping
1. Engineering plan submission shall include plans for:
a. Erosion control of cut and fill slopes;
b. Restoration of excavated areas; and
c. Tree protection in and below fill areas.
Section 4: Stormwater Design Criteria
4.12 Drainage and Floodplain Easements
4.12.2 General
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2. Landscaping should incorporate natural materials (earth, stone, and wood) on cut or fill
slopes wherever possible.
3. Applicant shall show in the plan the general nature and extent of existing vegetation on the
tract, the location of trees in accordance with the requirements of the tree survey required
by Section 7.7.4.E of the DDC, the areas which will be preserved, altered, or removed as a
result of the proposed alterations.
4. Locations and construction details should be provided, showing how trees will be preserved
in areas which will be altered by filling or paving within the drip line of those trees.
5. Applicant shall also submit plans showing location, type, and size of new plant materials and
other landscape features planned for altered flood plain areas.
4.12 Drainage and Floodplain Easements
4.12.1 General
A. Drainage and floodplain easements shall be provided for all open natural streams or manmade
drainage facilities. Easements shall encompass all areas lower than a ground elevation defined as
being the highest of the following:
1. 15 feet outside the calculated fully developed water surface elevation and associated flood
boundary based on a design storm whose frequency is 100 years. All contributing watersheds
are to be treated as fully developed for purposes of calculating the water surface elevation.
2. The top of the high bank plus a minimum of 20 feet, if higher than stated in A.1. above.
3. Existing natural banks with a slope steeper than 4H:1V shall have the easement line no closer
than the intersection of a 4H:1V line extending from the toe of the slope to the proposed
grade at the top of the bank, plus an additional 15 feet.
4. Additional access area may be required according to Section 4.12.2 below.
4.12.2 Storm Drain Easements
A. Above Ground Systems
Where an access road is required adjacent to a channel, an additional easement area of a minimum
width of 15 feet shall be provided. The maximum cross slope shall be 2%. All access roads adjacent
to improved channels shall be located within the drainage easement.
1. No structures, pavement, landscaping, or other above-ground man-made improvement shall
be placed in a drainage easement, except where the easement is a public or private open
space or park. Any such improvement within a drainage easement must be approved through
a design deviation request.
B. Closed Systems
1. Easements for closed drainage systems shall meet the following minimum standards as
shown below in Table 4.12-A.
Section 4: Stormwater Design Criteria
4.12 Drainage and Floodplain Easements
4.12.3 Channel Access
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Table 4.12-A: Easement Requirements for Closed Drainage
Systems
Pipe or Box Size Minimum Easement Width (feet)
36 inches and under 16
42 to 54 inches 20
60 to 66 inches 25
72 inches and above 30
2. Utilities such as water and sanitary sewer lines may share a portion of a drainage easement,
containing an underground enclosed drainage system where an additional easement width
for a minimum of 10 feet is added to create a public drainage and utility easement. No
utilities shall be located in any lined channel, pipe, or box in such a way as to interfere with
flow capacity or maintenance of or access to the channel, pipe or box.
3. A drainage easement shall be provided for the area within a required outfall channel or ditch
to the point where the flowline “day lights” on natural grade or matches existing topography.
4. To provide for maintenance, a drainage easement shall be provided at least 25 feet beyond
any outfall headwall.
5. No structures, pavement, landscaping, or other above-ground man-made improvement shall
be placed in a drainage easement containing a closed drainage facility.
4.12.3 Channel Access
A. Access areas and ramps shall be provided for all publicly maintained channels to allow for
maintenance of the channels. These access areas and ramps shall be contained within a drainage
easement. Access areas shall have a width of at least 12 feet, a minimum cross slope of 2%, and a
maximum cross slope of 5%.
B. Access easements shall be provided from the public ROW to the access area, if the access area is
not directly connected to the public ROW. Access easements shall remain free of obstacles that
block the use of the easement, including ungated fencing across the easement.
C. A concrete drive approach serving the access easement must be available and free of obstructions.
Any sidewalk crossing the access easement must be constructed using a residential street cross -
section, or otherwise designed to accommodate vehicle loads so that equipment may use the
access easement without damaging the sidewalk.
D. Access to all improved earthen channels shall be provided by one (1) of the following methods,
depending on the size and depth of the channel:
1. A clear access area must be provided on one side of the improved earthen channel along
the full length of the channel; or
2. If the channel is deeper than 4 feet or has a top width greater than 25 feet, an access area
must be provided on both sides along the full length of the channel. Access areas shall have
a width of at least 15 feet, a minimum cross slope of 2%, and a maximum cross slope of 5%.
E. All lined channels, and earthen channels with concrete pilot channels shall have a minimum bottom
width of ten (10) feet and shall be provided with concrete access ramps. Concrete access ramps
Section 4: Stormwater Design Criteria
4.13 Water Quality
4.13.1 Detention Facilities Easements
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shall have a minimum width of 12 feet, maximum slope of 6H:1V, and maximum cross slope of 5%.
All access roads shall be located within a dedicated easement. Access road pavement cross-sections
shall conform to the standards of the concrete residential street cross-section detail located in the
City of Denton Standard Details.
4.12.4 Detention Facilities Easements
A. Detention facility easements must encompass the entirety of the detention facility plus any required
maintenance access areas adjacent or leading to the facility.
B. All detention maintenance access easements must be connected to a public ROW, be a minimum
of 10 feet wide, and be free of obstructions which could prevent personnel and equipment from
accessing the detention facility.
4.12.5 Post-Construction Water Quality Control Structure Easements
A. All post-construction structural stormwater control structures must be located within an inspection
access easement. The intent of this easement is to allow City staff to access and inspect the control
structure to ensure it is being maintained in accordance with the SWFMA. This easement must be
connected to a public ROW, be a minimum of five (5) feet wide, and be free of obstructions which
could prevent City staff from accessing the control structure.
4.12.6 Fences
A. Fences in drainage easements are prohibited by the DDC, except as specifically provided for below.
1. Fences may cross drainage easements that contain an underground stormwater system
provided the fence is constructed with any type of non-masonry material and the fence is
constructed with knock-out panels to facilitate maintenance.
2. Fences in drainage easements that contain overland flow may cross the easement if the fence
is constructed with wrought iron (pickets and rails), pipe, or pipe and cable. Fence height,
minimum picket spacing, and maximum ground clearance spacing shall be governed by
appropriate child safety measures.
3. No fences are allowed across inlet or outlet structures of drainage detention facilities. Fences
are permitted around the detention facility if they do not block or inhibit the flow conveyance
of the detention facility.
4. No fencing is allowed across easements which share water or wastewater facilities with the
drainage facility.
B. Fences in the floodplain are prohibited.
4.13 Water Quality
4.13.1 Water Quality Protection Volume
It is required that all development sites disturbing a land area larger than one (1) acre or part of a common
plan of development disturbing a land area greater than one (1) acre treat their stormwater runoff either
through extended detention and/or include site development controls necessary to remove 80% of the TSS
from the water quality protection volume (WQV). See the iSWM™ Water Quality Protection Technical Manual
Section 4: Stormwater Design Criteria
4.13 Water Quality
4.13.3 Water Quality Hotspots
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for information regarding the design of this WQV and appropriate discharge design. See the iSWMTM Site
Development Controls Technical Manual for information regarding structural stormwater controls and their
ability to remove pollutants in stormwater runoff to protect water quality. Any combination of structural
stormwater controls may be used to achieve the required 80% TSS removal from all runoff from impervious
surfaces on the site. Any proposed proprietary treatment devices must be certified by either the New Jersey
Department of Environmental Protection (NJDEP), the Washington State Technology Assessment Protocol
– Ecology (TAPE) program, or the Technology Acceptance Reciprocity Partnership (TARP).
The percent TSS removal (%TSS) that is achieved on a site can be calculated using equation 4.8 below. This
equation is an area-weighted TSS reduction equation that accounts for the TSS reduction attributable to
each stormwater treatment best management practice (BMP) that is utilized on the site.
%𝑺𝑺𝑺= 𝚺𝒏 𝟎( 𝑺𝑺𝑺𝟎𝑨𝟎+ 𝑺𝑺𝑺𝟎𝑨𝟎+ … +𝑺𝑺𝑺𝒏𝑨𝒏)
𝚺𝒏𝟎 ( 𝑨𝟎+ 𝑨𝟎+ … +𝑨𝒏) [Eqn. 4.8]
Where: TSSn = TSS removal percentage for each structural BMP located on-site (%);
An = the area draining to each BMP (acres).
When two or more BMPs are used in series (stormwater discharges from one BMP into another), a different
calculation is necessary. This scenario is called a treatment train. Stormwater discharging from the upper
most BMP will be considerably “cleaner” than the influent, meaning TSS particle sizes will be much smaller.
Pollutant removal rates for BMPs used in a treatment train are not additive. To calculate the total % TSS
removal for a treatment train comprised of two or more structural BMPs, the following equation should be
used.
𝑺𝑺𝑺𝒕𝒓𝒂𝒊𝒏=𝑨+𝑨− 𝑨 ×𝑨
𝟎𝟎𝟎 [Eqn. 4.9]
Where: TSStrain = total TSS removal for treatment train (%);
A = % TSS removal of the first (upstream) BMP
B = % TSS removal of the second (downstream) BMP
4.13.2 Water Quality Hotspots
Not all structural stormwater controls are appropriate for receiving runoff from hotspots. Hotspots are land
uses or activities which produce higher concentrations of trace metals, hydrocarbons, or other priority
pollutants. Examples of hotspots might include gas stations, convenience stores, marinas, public works
storage areas, garbage transfer facilities, material storage sites, vehicle service and maintenance areas,
commercial nurseries, vehicle washing/steam cleaning sites, landfills, construction sites, industrial sites,
industrial rooftops, auto salvage or recycling facilities, and dog parks. Only appropriate structural
stormwater controls identified in the iSWMTM Site Development Controls Technical Manual may be used for
receiving hotspot runoff.
Facilities that discharge stormwater associated with industrial activity permitted under TCEQ Multi-Sector
General Permit (TXR050000) may incorporate WQv requirements into point source discharge control
requirements.
4.13.3 Required Stormwater Facility Maintenance Agreements
All private post-construction structural stormwater controls shall require a SWFMA in accordance with
Section 4.14 of this manual.
Section 4: Stormwater Design Criteria
4.13 Water Quality
4.13.4 Construction Erosion and Sediment Control Requirements
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4.13.4 Construction Erosion and Sediment Control Requirements
The criteria established in this Manual provide basic guidance for the design of erosion and sediment
control plans within the City of Denton. However, full responsibility and liability for proper design
remains with the designer. Users of this Manual should be knowledgeable and experienced in the
theory and application of best management practices (BMPs) for erosion and sediment control plans.
All land-disturbing activities must include provisions for erosion and sediment control in accordance with :
• DDC Subchapter 7.3: Land-Disturbing Activities
• DDC Subchapter 7.4: Environmentally Sensitive Areas
• The City of Denton Site Design Criteria Manual
• The City of Denton Construction Criteria Manual
• iSWM™ Criteria Manual for Site Development and Construction
• iSWM™ Technical Manual Planning Documents; and
• Public Works Construction Standards North Central Texas, Amended Fifth Edition (2023)
Other design criteria may be warranted from applicable resources. The Federal Government, the State of
Texas, NCTCOG, Denton County, Denton County Transit Authority (DCTA) and other related organizations
and resources shall be consulted for additional criteria as may be deemed necessary. Along with this Design
Manual, the DDC shall be consulted for additional guidance. The criteria established in this Manual do not
supersede the policies contained in the DDC. Any revision to the DDC supersedes the criteria in this Manual.
A. Erosion Control Plans
The purpose of the Erosion Control Plan is to reduce erosion, retain sedimentation and, to the
greatest extent, prevent off-site drainage during land-disturbing and construction activities. It does
this by assessing the site’s erosion potential to determine structural controls and site management
practices, also known as Best Management Practices (BMPs).
1. General Erosion Control Plan Requirements
The erosion control plan must contain the following:
a. A narrative description of the project, total acreage of the parcel, total acreage to be
disturbed, the construction sequence, the potential sources of erosion and
sedimentation, BMPs, their maintenance, and inspection procedures.
b. A list of BMPs that will be implemented during each phase of construction, such as
preservation of existing vegetation, stockpile management, silt fencing, outlet
protection, runoff interception, vegetated buffers, etc.
c. A sequence of construction of the development site, including stripping and clearing;
rough grading; construction of utilities, infrastructure, and buildings; and final grading
and landscaping. Sequencing shall identify the expected date on which clearing will
begin, the estimated duration of exposure of cleared areas, areas of clearing, installation
of temporary erosion and sediment control measures, and establishment of permanent
vegetation.
d. Description of on-site spoils and borrow areas, including handling and disposal of
borrow materials, as well as size, depth of fill and revegetation procedures.
e. Descriptions of on-site and adjacent critical areas
Section 4: Stormwater Design Criteria
4.13 Water Quality
4.13.4 Construction Erosion and Sediment Control Requirements
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f. Description of vegetative temporary and permanent stabilization practices
i. Areas within the limits of construction (LOC) that will require temporary
stabilization
ii. Seeding mixtures and rates, types of sod, method of seedbed preparation,
expected seeding dates, type and rate of lime and fertilizer application, and kind
and quantity of mulching for both temporary and permanent vegetative control
measures
iii. Specific limits on the time frame between initial exposure of soils by construction
activity to the temporary or final stabilization of those surfaces
iv. Schedule for converting temporary controls to permanent functions (e.g. basins)
g. Drawings and specifications of structural controls and site management practices, with
supporting calculations and assumptions
2. Phased Erosion Control Plans
For projects with earthwork construction totaling five (5) acres or more, a two-phased erosion
control plan is required for all non-linear projects. Each phase must be provided as a drawing
on a separate plan sheet. Drawings should address the transition between phases.
a. Phase 1 – Initial Land Disturbance: This drawing shows BMPs to be installed prior to
general clearing of the site. It should also show the existing contours, adjacent streets,
ROW, easements and property lines. Do not show final contours on this drawing.
i. Show the BMPs selected for the following:
a) Downslope perimeter controls
b) Side-slope controls as needed per site conditions
c) Controls that will intercept runoff
d) Access barriers for areas to remain undisturbed, such as ESA and tree
protection fencing
ii. Must show structures to be demolished and trees to be removed
iii. If installing sediment-trapping impoundments, such as sediment basins or
interceptor swales, they must be shown on this phase as they are installed at the
initiation of grading.
b. Phase 2 – Construction and Stabilization: This phase shows BMPs required during the
rest of grading and construction, such as inlet protection. It must also include BMPs
appropriate for final stabilization; seeding, sodding, flatwork, etc.
Individual Lot Phase: For single-family residential developments, the Phase 2 plan will
also show behind-the-curb controls, such as silt fencing, ground cover, and stabilized
construction entrances.
3. For projects with earthwork construction totaling less than five (5) acres, phased erosion
control plans are not required; the erosion control plan may be shown on a single sheet with
the following:
a. Show existing contours ;
b. Show final contours;
c. Show direction of flow during grading operations with arrows;
d. Show areas to be permanently stabilized.
Section 4: Stormwater Design Criteria
4.13 Water Quality
4.13.4 Construction Erosion and Sediment Control Requirements
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B. Mass-Graded Drainage Area Map
In addition to an existing conditions drainage area map (DAM) and proposed conditions DAM, sites
with earthwork construction ten (10) acres or greater must provide a mass-graded DAM showing
interim contours and temporary drainage conditions created by earthwork construction and soil-
leveling activities.
1. General Mass-Graded Drainage Area Map Requirements
a. Show the delineation and contributing drainage area of temporary basins;
i. Temporary basins can only flow to existing features; do not show features from the
proposed drainage area map.
b. Show and label contours created by earthwork construction. Do not show precise
grades such as building footprints, lot lines, or finished floor elevations.
c. Show the direction of flow for each temporary basin using arrows.
d. Show the locations of any temporary sediment-trapping impoundments, such as
sediment basins or traps, or interceptor swales (optional).
2. For Sites with Ten (10) Acres or More Common Drainage
a. Show and label the locations of any sediment-trapping impoundments, such as
sediment basins or traps, or interceptor swales.
C. Sediment Basins
A sedimentation basin or similar sediment-trapping impoundment is required where 10 or more
acres drain to a common area during any phase of development. Where other sediment-trapping
devices are used, such as interceptor swales, the below requirements apply.
1. Sediment basins and other detention structures must provide storage volume for the runoff
from a 2-year, 24-hour storm. Calculations must be included with the erosion control plan.
2. Sediment basin(s) or impoundments must provide at least 3,600 cubic feet (cu. ft.) of storage
per acre drained until final stabilization of the contributing drainage area.
3. Sedimentation basins or impoundments must be designed by a PE licensed in Texas or a
Certified Professional in Erosion and Sediment Control (CPESC)
4. Sediment basins must be able to control and treat runoff within site boundaries; they should
be installed as close as possible to the disturbed area or sediment source as possible. Existing
detention or retention ponds at the site may not be appropriate, as determined by City
review staff.
5. Sediment basins must be designed, constructed, and maintained to minimize mosquito
breeding habitats by minimizing the creation of standing water. Outlet structures shall be
designed to provide a minimum dewatering time of 36 hours and a maximum dewatering
time of 72 hours.
6. When discharging from sedimentation basins and impoundments, the plan must utilize
outlet structures that withdraw water from the surface. If this is infeasible, a reason must be
provided to City review staff during planning.
D. Vegetation
1. Criteria for Stabilization
Section 4: Stormwater Design Criteria
4.13 Water Quality
4.13.4 Construction Erosion and Sediment Control Requirements
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You are required to stabilize exposed portions of your site in accordance with DDC § 7.3.5.E,
the TXR150000 CGP, the NPDES CGP, and federal “C&D Rule” permit requirements as found
in 40 CFR 450.21. To be considered adequately stabilized, you must meet the criteria below
depending on the type of cover you are using, either vegetative or non -vegetative:
a. Vegetative Stabilization: If you are vegetatively stabilizing any exposed portion of your
site through the use of seed or planted vegetation, you must provide established
uniform vegetation (e.g., evenly distributed without large bare areas), which provides
70 percent or more of the density of coverage that was provided by vegetation prior to
commencing earth-disturbing activities.
i. Immediately after seeding or planting the area to be vegetatively stabilized, to the
extent necessary to prevent erosion on the seeded or planted area, you must select,
design, and install non-vegetative erosion controls that provide cover (e.g., mulch,
rolled erosion control products) to the area while vegetation is becoming
established.
ii. For final stabilization, vegetative cover must be perennial
b. Deadline to Initiate Stabilization: You must initiate soil stabilization measures
immediately whenever earth-disturbing activities have permanently or temporarily
ceased on any portion of the site.
i. The term “immediately” means as soon as practicable, but no later than the end of
the next workday, following the day when the earth-disturbing activities have
temporarily or permanently ceased.
ii. Earth-disturbing activities have temporarily ceased when clearing, grading, and
excavation within any area of the site that will not include permanent structures
will not resume (i.e., the land will be idle) for a period of 14 or more calendar days,
but such activities will resume in the future.
iii. The City closely adheres to the EPA’s Construction General Permit and will consider
any of the following types of activities to constitute the initiation of stabilization.
a) prepping the soil for vegetative or non-vegetative stabilization;
b) applying mulch or other non-vegetative product to the exposed area;
c) seeding or planting the exposed area;
d) starting any of the three activities stated just above on a portion of the area
to be stabilized, but not on the entire area; and
e) finalizing arrangements to have stabilization product fully installed in
compliance with the applicable deadline for completing stabilization
c. Deadline to Complete Stabilization Activities. As soon as practicable, but no later than
14 calendar days after the initiation of soil stabilization measures, you are required to
have completed:
i. All activities necessary to initially seed or plant the area to be stabilized.
ii. You are required to have stabilized the exposed portions of your site prior to
terminating permit coverage. You must submit your notice of termination (NOT)
within 30 calendar days of completing earth-disturbing activities at your site.
2. Vegetative stabilization is required for all permanent and temporary channels and basins.
Plant selection guidance is provided in the iSWM™ Landscape Technical Manual.
3. The erosion control plan must demonstrate reasonable preservation of trees and understory
Section 4: Stormwater Design Criteria
4.13 Water Quality
4.13.4 Construction Erosion and Sediment Control Requirements
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and that the following criteria is demonstrated in selection of trees to be preserved or
removed:
a. Proximity of the trees critical root zone or drip line to proposed grading activity.
b. Permanent tree protection methods are employed to protect the preserved tree from
damage where the trees critical root zone may be impacted.
c. Other measures have been employed, including site design that improves the chances
for tree survival.
d. Temporary tree protection methods are adequately employed.
e. Construction methods for utility service to the site are used that allow protection and
preservation of additional trees, such as, tunneling under the critical root zone, tree
walls, or tree wells.
f. Utility trenching activities are indicated on the plan.
E. Structural Controls and Site Management Practices
1. Erosion and sediment control BMP design criteria shall adhere to the most current version
of the iSWM™ Construction Controls Technical Manual, unless one of the following
exceptions applies:
a. Linear projects may follow TxDOT standards; or
b. Proprietary erosion or sediment control devices may be utilized when:
i. Independent performance data is provided to prove a demonstrated capability of
meeting a stormwater management efficiency equivalent to iSWM™ methods; and
ii. Supplementary data for systems or devices, such as instruction manuals and
specification sheets, are provided and are demonstrated to be appropriate for use
in North Central Texas site conditions, as determined by Environmental Services
and Sustainability (ESS) department staff.
2. The City has restrictions on certain structural controls:
a. Curb inlet protection requires ESS approval to be used on active City streets
i. Organic filter tube curb inlet protection is prohibited
ii. Block and gravel filter curb inlet protection is prohibited
iii. Curb rock sock on-grade curb inlet protection is prohibited
F. Procedures During Construction
The Watershed Protection Division of the Environmental Services & Sustainability Department is
primarily responsible for the inspection and enforcement of erosion and sedimentation control
requirements on site developments and subdivisions. The City will m onitor compliance with plan
requirements and judge the effectiveness of the controls during different stages of construction
and before and after significant rainfall. The criteria and procedures contained in this section closely
adhere to DDC § 7.3.4-6, the TXR150000 CGP, the NPDES CGP, and federal permit requirements as
found in 40 CFR 122.26 & 123.25.
1. Criteria for Approvals Required Prior to the Commencement of Land-Disturbing Activities
a. The project must have a valid, current city development permit or site plan.
Section 4: Stormwater Design Criteria
4.13 Water Quality
4.13.4 Construction Erosion and Sediment Control Requirements
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b. The developer, owner, or otherwise delegated applicant shall complete the appropriate
survey(s)
i. Applicants requiring a demolition permit must complete the Demolition Survey
ii. Applicants requiring all other permits must complete the Construction Survey
c. The applicant shall provide approved site plans and specifications for the development
permit. For plans to be accepted, the locations and dimensions of all temporary and
permanent erosion and sediment controls must be depicted. Specifications must
include the maintenance routines, and schedules for installation and removal of
controls, through all phases of construction.
d. If the project requires a Stormwater Pollution Prevention Plan (SWPPP), the plan must
be reviewed for completeness by City staff.
i. The SWPPP must show consistency with City-approved plans (i.e. civil engineering
plans and zoning compliance plans)
e. Projects disturbing five (5) or more acres must submit a Notice of Intent to the City; or
when the project is part of a common plan of development with disturbed acreage
totaling five acres or more.
f. Construction Site Notice (CSN)
i. Executed CSN(s) are included in the SWPPP.
ii. CSN(s) are posted publicly in locations near the site entrance, where they can be
viewed by the general public.
2. Compliance Inspection by the City
a. The project must pass an initial inspection for approval of permits and/or Notice to
Proceed.
i. The project must be in substantial compliance with the approved plans and
specifications (ESCP) for the development permit
ii. Controls must be installed in all required areas, such as:
a) Perimeter controls
b) Stabilized construction exit
c) Protection of existing inlets
iii. Clearing for the installation of erosion control devices shall not exceed a width of
eight (8) feet and must not encroach into the dripline or critical root zone of any
tree to be protected.
b. The project will be routinely inspected during all phases of development to determine
the compliance or non-compliance of a project's temporary erosion and sedimentation
controls.
i. Erosion and sediment controls must be installed for current development phase.
ii. Sediment basins (when required) must be installed at the initiation of grading at
the associated drainage area; the deadline for installation is seven days after
initiation.
iii. Vegetative temporary stabilization measures must demonstrate consistent
progress toward stabilization. See previous section for criteria.
Section 4: Stormwater Design Criteria
4.14 Stormwater Facility Maintenance Agreements
4.14.2 Maintenance Agreements
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iv. Permanent stabilization must be initiated within 48 hours of completion of
construction activities on areas of the site and completed for project prior to
issuance of final Certificate of Occupancy.
v. Vegetative stabilization must demonstrate consistent progress toward 70% density
of perennial vegetative cover.
3. Reinspection
a. Reinspection is conducted for sites that are out of compliance.
i. Standard timeframe for corrections is seven (7) business days.
ii. Enforcement may be escalated if there are impacts to offsite property or waterways.
iii. A reinspection fee may be assessed.
b. Reinspection with Notice of Violation (NOV) will be issued for continued stormwater
non-compliance affecting stormwater, with reinspection fee assessed.
c. Reinspection with Stop Work Order (SWO) – Escalation issued for continued non-
compliance affecting stormwater through failed erosion and sediment controls.
Reinspection fee assessed.
i. Effective until deficiencies are corrected.
ii. Erosion and sediment control failures which threaten life or property may result in
SWO without prior reinspection or NOV.
d. Reinspection Fees
i. Applicability – applies only to reinspection due to failure to comply with site
stormwater quality requirements.
ii. Amount – As established in the Water and Wastewater Rate Book.
iii. Time of Payment – Payment is due per standard City of Denton utility billing dates.
4.14 Stormwater Facility Maintenance Agreements
4.14.1 Maintenance Agreements
All drainage improvements constructed within a development and any existing or natural drainage systems
shall require a maintenance agreement that identifies responsible parties for maintenance. The maintenance
agreement shall be written such that it remains in force upon sale of transfer of the property.
As part of the Operations and Maintenance Plan submittal, a SWFMA must be prepared by the engineer of
record for each stormwater control that will not be wholly maintained by the City. This agreement must
outline preventive maintenance tasks and major repairs, identify the schedule for each task, assign clear
roles to affected parties, and provide a maintenance checklist to guide future owners, including an annual
self-inspection to be provided to the City. Multiple stormwater controls may be contained within a single
Stormwater Facility Maintenance Agreement. When areas are identified for detention that also serve other
purposes for the development (e.g. parking lots, loading docks) the requirement for a SWFMA may be
waived.
4.14.2 Private Maintenance (SWFMA Required)
A. Private drainage facilities include those drainage improvements which are located on private
property and which serve the needs of private development.
Section 4: Stormwater Design Criteria
4.14 Stormwater Facility Maintenance Agreements
4.14.3 Maintenance Agreement Requirements
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B. Private drainage facilities may also include detention or retention ponds, dams, and retaining walls
intended to direct or contain runoff. Such facilities must be designed in accordance with sound
engineering practices and reviewed and inspected by the City.
C. All SWFMA exhibits shall be reviewed and approved by the City with the civil engineering plans.
The agreement for perpetual maintenance of private drainage facilities shall be executed with the
City during per-construction. This agreement shall run with the land and can be tied to commercial
property or to an owner’s association, but not to individual residential lots.
D. The SWFMA shall provide the City with access to all private drainage facilities.
4.14.3 Maintenance Agreement Requirements
Details of the SWFMA must be set forth in a series of exhibits:
A. Exhibit A Legal Description - This includes the Metes and Bounds, a Surveyor’s Drawing of the area
occupied by the facility, and a copy of the preliminary or recorded plat containing the facility.
B. Exhibit B Design Plan and Specifications - These are summary documents intended for the use of
future owners in conducting routine maintenance, inspections, and repairs. The documents include:
1. Design Data and Calculations - This can be in the form of a letter or statement from the
engineer of record which summarizes critical design calculations related to the functionality
of the facility, such as storage volume or TSS removal, and attests to the facility conforming
to applicable iSWM standards;
2. Schematic Plan - This should be prepared by the engineer of record from construction
drawings to show the general layout of the facility. Major features requiring regular or special
maintenance should be shown and labeled in general terms understandable to a layman. A
profile should be given showing critical elevations that control the function and capacity of
the facility, and one or more cross-sections should be provided to indicate the general
grading of the facility. A typical example of a schematic plan for a simple detention basin is
shown in Figure 4.13 below; and
3. Landscaping - Vegetation should be shown consistent with the accepted Landscape Plan,
either on the Schematic Plan or as a separate drawing.
C. Exhibit C Operations and Maintenance Plan - Specific maintenance tasks should be defined for each
element of the facility. Maintenance tasks specific to the facility should be described in simple terms
consistent with terminology contained in the Schematic and Landscape plans. An inspection and
maintenance frequency should be established for each task.
D. Exhibit D Maintenance Checklist - A checklist consistent with the Operations and Maintenance Plan
shall be provided for the use of future owners in performing routine and special maintenance tasks.
This list should describe work required and frequency in language that is easy to understand and
specific for the facility to be maintained. This form will be completed by the Owner and submitted
to the City annually as part of a regular self -inspection program. See Appendix A for an example
checklist for preparing a SWFMA for a simple detention basin.
Additional facility maintenance guidance for several types of stormwater controls is provided in the iSWM
Technical Manual. The engineer of record must certify that the construction has been completed in
accordance with the general plans and Schematic Plan. After approval of construction by the City, the
engineer of record is expected to provide guidance to the owner’s representative in implementing the
accepted maintenance program and to co-sign the first annual inspection after the construction.
Section 4: Stormwater Design Criteria
4.14 Stormwater Facility Maintenance Agreements
4.14.3 Maintenance Agreement Requirements
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Figure 4.12 Simple Detention Basin Plan Schematic
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Section 5: Transportation Design Criteria
5.1 Overview
The purpose of Section 5 – Transportation Design Criteria is to provide minimum guidelines for the design
and construction of transportation infrastructure within the City of Denton, Texas and its extraterritorial
jurisdictions using the complete street and context-sensitive solution approach. The goal is to create safer,
more livable places that are consistent with their social, environmental and economic values.
It is the responsibility of the design engineer to ensure the final design of transportation infrastructure are
in conformance with the most recently adopted versions of the following documents:
A. City of Denton Mobility Plan;
B. City of Denton Code of Ordinances, Chapter 18 – Motor Vehicles and Traffic, and Chapter 25 –
Streets, Sidewalks and Public Places;
C. The North Central Texas Council of Governments (NCTCOG) Public Works Construction Standards;
D. DDC Subchapter 7.8 – Access and Circulation;
E. DDC Subchapter 7.9 – Parking and Loading;
F. DDC Subchapter 8.3 – Subdivision Design;
G. Americans with Disabilities Act (ADA) Standards for Accessible Design;
H. Public Right-of-Way Accessibility Guidelines (PROWAG);
I. The International Fire Code (IFC);
J. this Manual; and
K. relevant TxDOT, USDOT, NCHRP, FHWA, and AASHTO publications.
The criteria established in this Manual provide basic guidance for the design of transportation systems
within the City of Denton. However, full responsibility and liability for proper design remains with the
design engineer. Users of this Manual should be knowledgeable and experienced in the theory and
application of transportation engineering.
Other design criteria may be warranted from applicable resources. The Federal Government, the State of
Texas, NCTCOG, Denton County, Denton County Transit Authority (DCTA) and other related organizations
and resources shall be consulted for additional criteria as may be deemed necessary. Along with this Design
Manual, the DDC shall be consulted for additional guidance. The criteria established in this Manual do not
supersede the policies contained in the DDC. Any revision to the DDC supersedes the criteria in this Manual.
5.1.1 Organization
Section 5 - Transportation Design Criteria is organized as follows:
A. Overview
B. Mobility Framework
C. Roadway Design
D. Intersection Design
Section 5: Transportation Design Criteria
5.2 Mobility Framework
5.2.1 Roadway Functional Classifications
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E. Auxiliary Roadway Design
F. Access Management
G. Bike and Pedestrian Facility Design
H. Transit Facility Design
I. Traffic Impact Analysis Guidelines
J. Pavement Design Standard
K. Complete and Context-Sensitive Streets
5.2 Mobility Framework
The City of Denton Mobility Plan should be reviewed relative to any proposed development.
It should be noted that the City of Denton Mobility Plan is a living document and is periodically updated to
reflect the changes in the characteristics of anticipated traffic flow within the City.
5.2.1 Roadway Functional Classifications
The City of Denton uses the following roadway functional classifications in guiding developments and street
improvements within its jurisdiction. They are to be used in conjunction with other City of Denton
documents, as well as Complete Streets, Vision Zero, and Context-Sensitive Design considerations. These
classifications were established in the Thoroughfare Plan based upon expected fully developed traffic
volumes.
A. Freeway
Freeways are high-capacity roadways intended to move large volumes of traffic through the region,
into, and out of the City of Denton. They are typically managed and maintained by external agencies
such as TxDOT and may include tolled or non-tolled facilities. Freeways are limited-access facilities
as defined in Section 5.6 Access Management of this Manual.
These facilities are designed as multi-lane, high-speed roadways with on- and off-ramps to control
access and support long-distance regional and interstate travel. In urban areas, freeways are often
accompanied by frontage roads that provide access to adjacent properties and businesses.
This Manual does not prescribe specific design standards for freeways, as their planning, design,
and construction fall under the jurisdiction of TxDOT or other applicable agencies.
B. Primary Arterial
Arterial streets are streets that serve major routes into and through the City of Denton. They are
often multi-lane thoroughfares that generally include a landscaped median. Arterial streets are
shown on the City Mobility Plan. These street types are to have limited access as defined in Section
5.6 Access Management section of this Manual.
Primary arterials provide regional connectivity between different areas of Denton County and the
DFW region. The design of arterial can vary depending on the surrounding land use and
development. In urban areas, arterials may have wider sidewalks with smaller building setbacks,
while suburban areas may have limited sidewalks with a larger buffer between the edge of the street
and the building fronts. Refer to City of Denton Standard Details T112A and T112C for typical cross-
section requirements and design guidance.
Section 5: Transportation Design Criteria
5.2 Mobility Framework
5.2.1 Roadway Functional Classifications
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C. Secondary Arterial
Secondary arterials provide shorter connections and carry less traffic. Secondary arterials are still
significant to vehicular travel as they serve trips of moderate length and provide more land access.
They have a greater role in balancing local land access with moving people and goods. Typically,
they have lower travel speeds and traffic volumes than Primary arterials. They also tend to be limited
in width by the built environment that they serve and often have the greatest need for
accommodation of high levels of use for all travel modes. Refer to City of Denton Standard Details
T110A and T110C for typical cross-section requirements and design guidance.
D. Major Collector Street
A major collector is a roadway that collects and distributes traffic between collector streets/ local
streets and arterial roads, supporting moderate traffic volumes. It typically accommodates 2–4 lanes
and operates at lower speeds. Major collectors balance mobility and access, featuring wider lanes,
occasional medians, and turn lanes to improve flow. These roads often include sidewalks, bike lanes,
or shared-use paths, making them suitable for moderate-distance trips between neighborhoods,
schools, and commercial areas. Refer to City of Denton Standard Details T113A-T115A and T113C-
T115C for typical cross-section requirements and design guidance.
E. Collector Street
A collector street is a street that collects associated traffic from residential streets, rural streets,
commercial streets, or industrial streets as designated on the City Mobility Plan.
Collectors in the City of Denton provide local land access and traffic circulation from residential
neighborhoods to arterials or major collectors. They typically experience lower traffic volumes and
have lower design speeds. Collector classifications include the following:
1. Commercial Collector – Provides circulation between commercial developments and the arterial
or major collector system. Refer to City of Denton Standard Details T108A and T108C for cross-
section requirements and design guidance.
2. Residential Collector – Functions as a residential street but is designed to accommodate higher
traffic volumes and wider pavement widths than standard residential streets. Parking may be
permitted depending on the context and adjacent land uses. Refer to City of Denton Standard
Details T107A and T107C for cross-section requirements and design guidance.
F. Local Streets
A local street is a public street that provides access to adjacent property and are usually contained
within the neighborhood. These streets have low speeds and low volumes associated with them.
Local streets may be further classified into the following two (2) types:
1. Residential Street – A residential street is a public street associated with residential
development within an urban environment. The residential street may accommodate on-
street parking, dependent on the context and adjacent land uses. Refer to City of Denton
Standard Details T105A and T105C for cross-section requirements and design guidance.
2. Rural or Suburban Residential Street – A rural street is a public street that connects rural
communities. Refer to City of Denton Standard Details T106A and T106C for cross-section
requirements and design guidance.
Existing or new industrial developments on local streets shall consult with the City’s Engineer.
Section 5: Transportation Design Criteria
5.2 Mobility Framework
5.2.2 Auxiliary Roadway Classifications
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5.2.2 Auxiliary Roadway Classifications
Roadways that cannot be classified as thoroughfare, are grouped together as auxiliary roadways and are
classified here as follows:
A. Alleys
An alley (residential or commercial) is designed to provide access to the rear of or side of a lot
including solid waste and fire access. These pathways are narrower than standard streets, usually
measuring 20 feet wide public ROW and are not intended for through traffic but rather for serving
adjacent properties. Alleys will be required for residential streets prohibiting on-street parking.
Alleys are required in non-residential zoning districts where necessary to provide for adequate
access for service vehicles, off-street loading or unloading, access for emergency vehicles, fire
access or similar reasons consistent with the intent of the DDC.
B. Drives
A drive is an unobstructed paved area providing vehicular access from a street to a developed
property. Drives can be classified as follows:
1. Driveway - A driveway is located entirely on private property. It is only for a single-family or
a duplex property. It connects a drive approach to a garage, carport, parking pad or the like.
2. Drive Aisle - A drive aisle is located entirely on private property. It is for every other condition
other than for a single-family or a duplex property. It connects a drive approach to an area(s)
that is to be accessed on the site such as, but not limited to: parking space(s); loading dock(s);
loading area(s) (marked or implied - for passengers and/or goods); porte-cochere(s), and/or
the like. It can also be a fire apparatus access road (in and of itself or in conjunction with
other access use[s]). It can also be an access to an adjoining property (in and of itself or in
conjunction with other access use[s]).
3. Drive Approach - A drive approach connects a street (city, public or private) or highway
(TxDOT) with a drive aisle. Some features of the drive approach may extend into and be a
part of the driveway or drive aisle. The drive approach is measured from the face of the
roadway curb to the end of the curb return radius on the private property. The following
provides the types of drive approaches considered within this Manual:
a. Single-family residential: A drive approach to a single-family residential lot or one lot
duplex.
b. Multifamily residential: A drive approach to a multifamily lot such as triplexes,
fourplexes, and multi-complexes. The drive approach can be either the main entrance
approach or the secondary entrance approach. Each type has specific design
requirements.
c. Commercial: A drive approach to a commercial development. The drive approach can
be either the main entrance approach or the secondary entrance approach. Each type
has specific design requirements.
d. Industrial: A drive approach to an industrial development. The drive approach can be
either the main entrance approach or the secondary entrance approach. Each type has
specific design requirements.
e. Mixed-use approach: A drive approach that is a mixed-use development shall consider
the more stringent criteria for the approach design.
Section 5: Transportation Design Criteria
5.3 Roadway Design
5.3.2 Design Controls
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4. Flag Drives - A flag drive is a private road within a private access easement, which may serve
up to three (3) residential dwelling units. Flag drives shall have direct access to a public street
other than an alley. They shall not, however, provide direct access to an arterial street.
C. Cul-De-Sacs, Dead-End Street, and Hammerhead Turnarounds
A cul-de-sac is a form of dead-end street that terminates with a circular or bulb-shaped turnaround,
designed to accommodate fire apparatus and large vehicles for safe and efficient maneuvering.
A half cul-de-sac incorporates a 90° ± 5° bend, typically applied to residential or residential collector
streets, and provides limited turnaround capability. In contrast, traditional dead-end streets share
similar geometric characteristics with cul-de-sacs but terminate abruptly without a defined
turnaround, restricting emergency access and vehicular circulation.
Hammerhead turnarounds are configured in a T-shaped or L-shaped layout at the end of a dead-
end street, providing adequate space for large vehicles to complete a three-point turn. This option
is commonly applied in constrained sites where a full cul-de-sac is not feasible.
To support overall street connectivity and circulation, the use of cul-de-sacs, dead-end streets and
hammerhead turnarounds should be avoided if possible.
5.3 Roadway Design
5.3.1 Design Controls
Traffic volumes and speed are necessary for the design of roadways, and assist with the planning and design
of ROW, number of lanes, turn-lanes, need of intersections, and bicycle and pedestrian facilities. Guidance
on these design controls will be discussed at the pre-design meeting.
5.3.2 Street Sections
Street section standards are provided for arterial, collector, and local streets in Table 5.3-A below. Refer to
the City of Denton Standard Details for cross-section details. Options for street sections are dependent
upon treatment utilization within the street section. Besides defined lanes, other treatments that can be
utilized within the street sections include on-street parking, bike lanes, multi-use paths, and transit facilities.
The intent is to provide options in order to develop a “complete street” with “context-sensitive” design; See
Section 5.11 of this Manual. ROW requirements may vary at intersections based upon turning movement
requirements.
In general, street grades shall follow the natural contour of the property and be below the existing grade
so that the parkway drains towards the street. Excessive cuts and fills solely for the purpose of balancing
earthwork are not permitted.
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Table 5.3-A : Geometric Roadway Standards
Criteria
Roadway Classification
FREEWAY PRIMARY
ARTERIAL
SECONDARY
ARTERIAL
SECONDARY
ARTERIAL
(ONE-WAY)
MAJOR
COLLECTOR
COMMERCIAL
COLLECTOR
RESIDENTIAL
COLLECTOR RESIDENTIAL
RURAL OR
SUBURBAN
RESIDENTIAL
ALLEY [6,7]
No. of Lanes [1]
As per
TxDOT
standards
6 4 2-3 3-4 3 2-3 2 2 2
Min. ROW [10] 135’ 110’ 65’ 110’ 65’ 65’ 55’ 65’ 20’
Pavement Width [2] (BOC to BOC) 84’ 62’ 35’ 48’-72’ 39’ 39’ 33’ 21’ [5] 15’ [5]
Median Width 14’ 14’ NA 0’-14’ NA NA NA NA NA
Parkway Width 25.5’ 24’ 15’ 18’-31’ 13’ 13’ 11’ 20’ NA
Min. Center Line Radius [3] 750’ 575’ 575’ 575’ 575’ 400’ 200’ 200’ 100’
Min. Horizontal Curve Separation 100’ 100’ 100’ 100’ 100’ 100’ NA NA NA
Min. Grade (%) 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5
Max. Grade [4] (%) 7 7 7 7 7 7 10 10 8
Design Speed (MPH) 40-45 35-40 30-35 30-35 30-35 30 30 30 10-15
On-street Parking Prohibited Prohibited Permitted [8] Prohibited [9] Prohibited Permitted [8] Permitted [8] Prohibited Prohibited
Notes:
[1] The number of travel lanes is dependent upon TIA and/or the City’s Engineer’s requirements.
[2] See Table 5.4-D, Table 5.4-E, Table 5.4-F, and Table 5.4-G, for additional ROW requirements at intersections with turn lanes.
[3] The minimum center line radius is based on the cross slope of -2% (no superelevation).
[4] The maximum grade within 60 feet of an intersection measured from the intersection curb is 2% or less.
[5] Measurement is edge-of-pavement to edge-of-pavement.
[6] If an alley is to be used for waste collection, it must meet all alleyway access requirements shown in Section 3: Solid Waste Design Criteria of this Manual.
[7] If an alley is intended to provide fire apparatus access, it must meet the design requirements of Section 5.6.3- Fire Apparatus Access Roads of this Manual.
[8] Parking is allowed unless otherwise prohibited by ordinance or by signs installed by the city.
[9] Parking is prohibited unless otherwise allowed by ordinance or by the City’s Engineer, in which case only parallel parking is permitted.
[10] The developer shall dedicate from one-half of the required ROW, measured from the centerline of the existing street alignment, up to the full width of the required ROW for City-maintained facilities, in
accordance with the City of Denton Mobility Plan.
[11] A 20-ft wide public utility easement is required along the property frontage where the property abuts a TxDOT-maintained roadway.
[12] The applicable standards, cross-sections, and design requirements shall be determined in coordination with the City Transportation Department.
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5.4 Intersection Design
Several components of intersection design are addressed in this section. These standards are to work in
concert with the Traffic Impact Analysis (TIA) requirements of this Manual. Additionally, the Pedestrian and
Bicycle Facility Design, Transit Facility Design, and the City of Denton Standard drawings for accessibility
should be reviewed for additional design requirements.
5.4.1 Geometry
A. Street intersections should be designed to be perpendicular; see tolerances shown in Table 5.4-A
below. All streets shall be aligned with any existing streets by continuation of the centerline thereof.
B. The staggering of street alignment resulting in “T” intersections shall leave a minimum distance of
150 feet between the curb faces of residential streets, and 200 feet between the curb faces of
collector streets.
C. Table 5.4-A and Figure 5.1 below provide requirements for ROW corner clips and curb return radius
at intersections. These standards provide minimum vision clearance areas without consideration to
stopping sight distance. Additional sight clearance evaluation should be performed as necessary,
as per Section 5.4.3 below.
Figure 5.1 Minimum Vision Clearance
Table 5.4-A: Intersection Geometry
Intersection Classification Intersection Angle
(degrees)
ROW
Corner Clip 1 (feet)
Curb Return
Radius (feet)
Arterial - Arterial 90±5 30 30
Collector - Arterial 90±5 20 30
Collector - Collector 90±5 15 30
Residential Street - Arterial 90±5 15 30
Residential Street - Collector 90±10 15 20
Residential Street - Residential Street 90±10 10 20
Flag Drive - Collector 90±10 5 20
Flag Drive - Residential Street 90±15 5 10
Alley - Collector 90±10 10 30
Alley - Residential Street 90±10 15 30
Alley - Alley 90±10 25 30
Section 5: Transportation Design Criteria
5.4 Intersection Design
5.4.2 Visibility Standards
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Notes:
[1] Shall apply to all corners of the intersection.
[2] Fences must provide a 5-ft. corner clip adjacent to driveways.
[3] Curb Return Radius is for single lane design. Multi-lane and special considerations for truck-turning radius require turn radius
analysis, as required by the City’s Engineer.
[4] Major Collector shall follow the arterial street standard.
5.4.2 Visibility Standards
Table 5.4-B and Figure 5.2 below shall be used to evaluate the required unobstructed view for motorists at
intersections, which are based upon the design speed approaching the intersection. Design speeds are
based upon the roadway classification. The values shown in the table are minimum standards. Within the
sight line area, no obstruction shall be allowed that will obstruct the view of motorists. A sight visibility
easement shall be dedicated to protect and maintain sight visibility.
A. Table 5.4-B below is based upon passenger car right turn and left turn from stop. Where truck
traffic warrants additional sight distance, refer to AASHTO Geometric Design of Highways and
Streets for single-unit truck and combination truck design requirements, Case B1 and Case B2.
B. Refer to AASHTO Geometric Design of Highways and Streets for multi-lane considerations and
other design considerations that may apply for Cases “A” through “F”.
C. Lines of sight distance at all intersections shall be clear at an elevation between two (2) feet and
nine (9) feet above the nearest gutter elevation.
Figure 5.2 Visibility Standards
Table 5.4-B: Visibility Standards
Design Speed
(mph)
Intersection Sight Distance
Near Side (feet)
Intersection Sight Distance Far
Side (feet)
30 290 335
35 335 390
40 385 445
45 430 500
Notes:
[1] Driveways accessing roadways shall use above table to satisfy intersection visibility compliance.
Section 5: Transportation Design Criteria
5.4 Intersection Design
5.4.4 Vertical Curve Standards
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5.4.3 Vertical Curve Standards
Vertical curves are required when two (2) street grades intersect at a point of vertical intersection greater
than 1%. Minimum vertical lengths for both crests or sags shall be defined by the design speed for the
street and the associated stopping sight distance, as well as the minimum K value. Table 5.4-C below shows
the minimum K value for various design speeds.
Table 5.4-C: Minimum ‘K’ Values for Vertical Curves
Design Speed
(mph)
Stopping Sight
Distance (feet)
Crest Vertical Curve
(K Min)
SAG Vertical Curve
(K Min)
30 200 19 37
35 250 29 49
40 305 44 64
45 360 61 79
Notes:
[1] Source: AASHTO Geometric Design of Highways and Streets ‘US Greenbook’.
Vertical curve lengths can be calculated as shown in Equation 5.1 below:
L = KA [Eqn. 5.1]
Where: L = Vertical Curve Length
A = Algebraic Difference in Grade
A. No vertical curve required for “A” equal to or less than 1.0%
B. Minimum spacing between successive vertical curves shall be 50 feet for residential, and 100 feet
for collectors and arterials.
C. Resultant vertical curve grade shall be no less than 0.3% for concrete pavement, and no less than
0.5% for asphalt pavement.
D. For drainage purposes, 50-ft. vertical curves are required when “A” is greater than 1.0% and less
than or equal to 1.2%. Otherwise minimum vertical curve length is 100 feet.
5.4.4 Turn Lane Requirements
Turning lane requirements shall be based upon the following requirements and/or the requirements of the
City’s Engineer, and the tables within this section.
A. Left-Turn Lane Warrants
When designing an intersection that provides direct or indirect access to the proposed
development, left-turn lanes should be provided at driveways and street intersections along major
arterial and collector roads, wherever left turns are permitted. Traffic-volume-based guidelines for
where left-turn lanes should be provided are presented in Tables 5.4-D (four-lane roadways) and
5.4-E (two-lane roadways) below.
Section 5: Transportation Design Criteria
5.4 Intersection Design
5.4.4 Turn Lane Requirements
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Table 5.4-D: Left-Turn Warrants for Four-Lane Roadways [1]
Source: AASHTO A Policy on Geometric Design of Highways and Streets
Left-Turn Lane Peak-
Hour Volume
(veh/hr)
Three-Leg Intersection, Major-Road
Peak-Hour Volume (veh/hr/ln) that
Warrants a Left-Turn Lane
Four-Leg Intersection, Major-Road
Peak-Hour Volume (veh/hr/ln) that
Warrants a Left-Turn Lane
5 450 50
10 300 50
15 250 50
20 200 50
25 200 50
30 150 50
35 150 50
40 150 50
45 150 <50
50 or More 100 <50
Notes:
[1] These guidelines apply where the major road is uncontrolled, and the minor -road approaches are stop- or yield-controlled. Both the
left-turn peak-hour volume and the major-road volume warrants should be met as shown in Figure 5.X.
[2] Major road volume shall be calculated as the total traffic volume from both approaches of the major roadway, divided by t he total
number of through lanes on those approaches.
Table 5.4-E: Left-Turn Warrants for Two-Lane Roadways [1]
Source: AASHTO A Policy on Geometric Design of Highways and Streets
Left-Turn Lane Peak-
Hour Volume (veh/hr)
Three-Leg Intersection, Major-Road Peak-
Hour Volume (veh/hr/ln) that Warrants a
Left-Turn Lane
Four-Leg Intersection, Major-Road Peak-
Hour Volume (veh/hr/ln) that Warrants a
Left-Turn Lane
5 200 150
10 100 50
15 100 50
20 or more 50 < 50
Notes:
[1] These guidelines apply where the major road is uncontrolled, and the minor-road approaches are stop- or yield-controlled. Both the left-
turn peak-hour volume and the major-road volume warrants should be met.
[2] Major road volume shall be calculated as the total traffic volume from both approaches of the major roadway, divided by t he total number
of through lanes on those approaches.
[3] Bypass lanes warrant analysis at three-leg rural intersections shall follow the TxDOT Roadway Design Manual.
Figure 5.3 below guides the left-turn lane design plan. Conditions for requesting a left-turn lane
include large truck volume, high crash history, limited sight distance, and significant delay for
motorists to make the turn, as determined by the City’s Engineer. Further discussion and examples
of left-turn lane guidance can be found in AASHTO's Policy on Geometric Design of Highways and
Streets.
Section 5: Transportation Design Criteria
5.4 Intersection Design
5.4.4 Turn Lane Requirements
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Figure 5.3 Left-Turn Lane
B. Right-Turn Lane Warrants
When designing an intersection that provides direct or indirect access to the proposed
development, right-turn lanes should be provided along major arterial and collector roads at
driveways when the right turns are permitted and satisfy the following criteria. Table 5.4- G below
provides criteria which warrant right-turn lanes. Figure 5.4 below provides guidance on right-turn
lane requirements.
Table 5.4-F: Right-Turn Warrants for Urban and Suburban Roadways
Roadway Classification Speed Limit (mph) Volume (Vehicles per Hour)
Arterial / Collector 45 or greater 50 or more
Arterial / Collector Less than 45 60 or more
Figure 5.4 Right-Turn Lane
Conditions for requesting an exclusive right-turn lane when right-turn traffic volume projections
are less than indicated in Table 5.4- G, include the following, as determined by the City’s Engineer:
1. Large volume of truck traffic,
2. High crash history,
3. Roadways with limited sight distance, or
4. Heavier than normal peak flow movements on the main roadway.
C. Turn Lane Geometry
When a turn lane is required, Table 5.4- H below shall be used as the minimum criteria for the turn
Section 5: Transportation Design Criteria
5.4 Intersection Design
5.4.5 Intersection Detail for Collectors and Arterials
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lane geometry. Additional consideration shall be given for unique traffic movements such as
excessive tractor trailer utilization, extended length transport vehicle movement, etc. See Section
5.4.5 below for additional geometry standards for Collectors and Arterials.
Table 5.4-G: Minimum Turn Lane Geometry
Intersection Type
Lane
Width
(feet)
Minimum
Storage
Length
(feet)
Minimum Taper
(feet)
Additional
ROW
Required
(feet)
LEFT
TURN
RIGHT
TURN
Residential Collector 11 100 100 100 15
Major/Commercial/Industrial
Collector 11 150 100 150 15
Secondary Arterial 11 150 100 200 15
Primary Arterial 11 200 100 200 15
Notes:
[1] Required turn lane storage may be greater depending upon the TIA.
[2] The Pedestrian Path shall be taken into account for access across the median by utilizing a leave-out or ramp in
accordance with accessibility standards described in this manual.
[3] Cross slope of median openings or turn bays shall not be more than 2% or less than 1%.
[4] On TxDOT Roadways, TxDOT Roadway Design Manual standards shall supersede City of Denton Standards.
[5] Taper Radius shall be 200 feet minimum.
[6] Additional ROW required per turn lane bay, if ROW is not sufficient.
5.4.5 Intersection Detail for Collectors and Arterials
Figure 5.5 below provides median location details and specific turn lane radius requirements. Also refer to
median details shown in the City of Denton Standard Details.
Figure 5.5 Intersection Detail for Collectors and Arterials
Notes:
1. For collector and arterial streets, A = 15 feet minimum.
2. Depending upon traffic flow requirements, the right turn may require a hooded right turn.
Section 5: Transportation Design Criteria
5.4 Intersection Design
5.4.7 Intersection Spacing
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5.4.6 Intersection Spacing
Standards for intersection spacing are outlined below in Table 5.4- H.
Table 5.4-H: Minimum Intersection Spacing 1
Roadway
Classification Alley Flag Drive Residential Collector Arterial
Alley 100 feet N/A 100 feet 100 feet N/A
Flag drive N/A N/A 75 feet 75 feet N/A
Residential 100 feet 75 feet 200 feet 2 200 feet 2 400 feet
Collector 100 feet 75 feet 200 feet 2 200 feet 2 400 feet
Arterial N/A N/A 400 feet 400 feet 1200 feet
Notes:
[1] Spacing will be measured between face of the curbs.
[2] 100-ft. minimum to the first intersection for entrances to subdivisions off of an arterial, where lots back up to the arterial.
5.4.7 Roundabouts
Roundabouts are circular intersections that create counter-clockwise traffic movements around a central
island, with entering traffic yielding to circulating traffic.
The design of a roundabout shall be in compliance with the Intersection Control Evaluation provided by the
FHWA. Normally, each roundabout will be unique in some way, as such a standard roundabout is not
included in this Manual. Also, the various analyses and design considerations involved in roundabout
design are beyond the scope of this Manual.
A. The following resources shall be used when designing a roundabout:
1. TxDOT Roadway Design Manual
2. NCHRP Report 1043: Guide for Roundabouts (2023)
3. Federal Highway Administration Roundabouts, An Information Guide
4. Federal Highway Administration Roundabouts, Technical Summary
B. In addition to the resources provided above, the roundabout design shall include the following
design review process with the City’s Engineer and City Staff:
1. Have a Pre-Application Conference on the project, which will include a separate meeting with
the City’s Engineer for proposed roundabout design considerations;
2. Have a Traffic Impact Analysis (TIA) review meeting with the City’s Engineer. See section on
TIA requirements;
3. Develop Preliminary layout of roundabout considering TIA and Pre-Development meetings;
4. Preliminary Design review meeting with the City’s Engineer;
5. Develop roundabout design based up comments from the City’s Engineer; and
6. Submit roundabout design through the Development Review Process (DRP).
Section 5: Transportation Design Criteria
5.5 Auxiliary Roadway Design
5.5.2 Alleys
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5.5 Auxiliary Roadway Design
5.5.1 Alleys
A. Alleys shall have at least two (2) direct access points to public streets and are subject to the block
length criteria included in this Manual.
B. Alleys shall be a minimum of 15 feet wide, with edges sloping towards the centerline at 3% slope.
C. No drainage infrastructure will be allowed within the alley ROW. Alleys shall be designed to convey
all runoff along the surface of the pavement.
D. Alleys that are intended to provide fire apparatus access must meet the design requirements of
Section 5.6.3-Fire Apparatus Access Roads of this Manual.
E. Refer to City of Denton Standard Detail T103C for further details.
5.5.2 Drives
The design criteria for drives detailed in this section should be utilized in conjunction with the standards
outlined in DDC 8.3 (Lot Planning). The following standards generally apply to all developments. However,
there may be unique situations for which these standards may be impractical. In these situations, the City’s
Engineer will work with the developer to develop a mutually agreeable solution. In the event that a mutually
agreeable solution is not reached, the developer may apply to the Planning and Zoning Commission for
consideration of the issue.
A. Drive Approach Standards
Table 5.5-A: Drive Approach Dimensions
Development Type 1 Drive Approach Widths Radius
MIN. WIDTH
(FEET)
MAX. WIDTH 2
(FEET) (FEET)
Residential – Single-family or Duplex 12 20 5 3
Residential – Multifamily 24 38 10 to 20
Commercial or Industrial 4 30 38 20 to 25
Notes:
[1] Driveways on TxDOT roadways - driveway width and curb radius shall meet TxDOT Roadway Design Manual
standards.
[2] Refer to Figures 5.6 through 5.10.
[3] If the drive approach is part of the fire apparatus access road, refer to Section 5.6.3 of this manual.
[4] Maximum drive approach width is a function of traffic volume.
[5] Add five (5) feet to maximum radius for significant truck traffic.
[6] For shared drive approaches, no lot shall contain less than nine (9) feet of the drive approach and driveway or
drive aisle (as may apply). Drive approach shall be centered on lot line, such that maximum drive approach
width equals 30 feet.
1. Residential
a. One (1) single-family or one (1) duplex residential lot accessing a collector may be
permitted to have one (1) full-width or circular drive approach (Figure 5.6 below), when
alleys are not practical.
b. Two (2) adjacent single-family or two (2) adjacent duplex residential lots accessing a
Section 5: Transportation Design Criteria
5.5 Auxiliary Roadway Design
5.5.2 Drives
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collector may be permitted to have one (1) shared full-width or circular drive approach,
when alleys are not practical.
c. Three (3) or more contiguous single-family or three (3) or more contiguous duplex
residential lots accessing a collector will be required to enter the collector by an alley,
flag drive, or residential street.
d. One (1) single-family or one (1) duplex residential lot accessing an arterial, will be
required to have an on-site facility, allowing entrance into the arterial in a forward
manner.
e. For homes with a 3-car garage or greater, where the garage door is street-facing and
less than 40 feet from the back of curb, the maximum drive approach width shall be 30
feet.
Figure 5.6 Residential Circular Drives
2. Commercial
a. All stop bar markings and stop signs when used shall be on private property, as well as
upstream of any pedestrian facility crossing the drive approach and/or drive aisle.
b. All signs and markings should be consistent with TMUTCD.
c. Drive approaches with significant truck traffic may install surmountable curb with
textured and colored pavement in the parkway, with a depth equal to or greater than
the drive approach pavement requirement.
d. Ingress/Egress Lanes
i. Single Lane Egress/Ingress (Figure 5.7) - The outbound (towards the street) lane
shall be a minimum of 12 feet wide; if the width of the driveway is greater than 30
feet, then the inbound (onto the site) lane shall be a minimum of 18 feet wide.
Section 5: Transportation Design Criteria
5.5 Auxiliary Roadway Design
5.5.2 Drives
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Figure 5.7 Drive Approach: Single Lane Egress/Ingress
ii. Dual Lane Egress, Single Lane Ingress (Figure 5.8) - The outbound lanes shall be 10
feet wide; if the width of the driveway is greater than 30 feet, then outbound lanes
shall remain 10 feet wide while the width of the inbound lane shall be increased.
Figure 5.8 Drive Approach – Dual Lane Egress, Single Lane Ingress
iii. Multiple Lane Egress/Ingress (Figure 5.9) - Only allowed when dual left-turn lanes
into the site or opposing street/driveway has two (2) or more lanes, of which two
(2) are designated as being through lanes.
a) Each of the two (2) outbound and inbound lanes shall be 10 to 12 feet wide.
b) Median shall accommodate any pedestrian facility across the drive approach
and/or drive aisle, as projected from both sides thereof.
Section 5: Transportation Design Criteria
5.5 Auxiliary Roadway Design
5.5.2 Drives
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Figure 5.9 Drive Approach – Multiple Lane Egress/Ingress
iv. Right-in or Right-out Egress/Ingress - The minimum width of the drive
approach/drive aisle prior to the island, each lane (inbound and outbound) at the
island, and the applicable radii shall be determined by the engineer of record,
based on expected vehicle type(s), as well as an auto-turn analysis provided to the
City’s Engineer for review and approval as part of the Civil Engineering Plan
submittal.
a) Median/island shall accommodate any pedestrian facility across the drive
approach and/or drive aisle as projected from both sides thereof.
b) For “one way in” or “one way out” driveways, the geometry shall be as shown
in Figure 5.10 below for the respective side.
c) Through a Design Deviation request, the minimum drive approach width may
be reduced based upon acceptable turning radius for emergency vehicles, and
determination that truck traffic requiring the larger width will not occur.
d) When the right in/right out drive approach is part of the fire apparatus access
road, the minimum width of each drive shall be 24 feet.
Figure 5.10 Drive Approach – Right in or Right out Egress/Ingress
v. With the exception of multi-lane egress/ingress (shown in Figure 5.9), drive
approaches with a median installed in lieu of the double-yellow marking, may
exceed the maximum drive approach width by the width of the median only.
Section 5: Transportation Design Criteria
5.5 Auxiliary Roadway Design
5.5.2 Drives
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vi. Right-in/right-out driveways along TxDOT frontage roads may be designed
without a porkchop unless the driveway is in close proximity to exit and entrance
ramps. A regular driveway approach with one-way signs is acceptable
B. Drive Approach Spacing
1. Same side of the street
Drive approach spacing shown in Table 5.5-B below applies to drive approaches on the same
side of the street, and is measured between the nearest edges of each drive approach, along
the back of curb, not including the radius.
Table 5.5-B: Minimum Drive Approach Spacing
Roadway Classification Min. Spacing 1 (feet)
Primary Arterial 200 2
Secondary Arterial 150 2
Major Collector/Collector 100 3
Residential Street 4 50
Flag Drive 10
Alley 10
Notes:
[1] Driveways on TxDOT roadways must meet the minimum spacing in the TxDOT Access Management
Manual, Table 2‑2.
[2] A maximum of two (2) drive approaches permitted. If a second point of access is required by City
Fire Code official, it must be remote, meaning driveways are spaced no less than half the diagonal
of the maximum overall dimension of the lot.
[3] If permitted; drive approaches are not permitted on arterial streets, unless otherwise allowed
according to Section 5.6 of this Manual.
[4] If permitted; refer to Section 5.6 of this Manual for permitted access.
[5] For a T-intersection on residential streets, the drive approach shall be offset farthest from the
intersection.
[6] Single-family driveways on residential streets require a minimum spacing of 10 ft.
2. Near Intersections
Drive Approach spacing shown in Table 5.5-C below applies to drive approaches near
intersections and is measured between the face of the curb of the intersecting street and the
nearest edge (face of curb) of the drive approach not including the drive approach radius;
see Figure 5.11 below.
Section 5: Transportation Design Criteria
5.5 Auxiliary Roadway Design
5.5.2 Drives
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Figure 5.11 Drive Approach Spacing at Intersections
Table 5.5-C: Minimum Drive Approach Spacing at Intersections
Intersection Type Approaching the Intersection Departing the Intersection
Arterial - Arterial 1 150 feet on both streets 200 feet on both streets
Collector - Arterial 1 75 feet on collector, 150 feet on arterial 100 feet on collector, 200 feet on arterial
Collector - Collector 75 feet on both streets 100 feet on both streets
Residential - Arterial 1 50 feet on residential, 150 feet on arterial 50 feet on residential, 200 feet on arterial
Residential - Collector 50 feet on residential, 75 on feet collector 50 feet on residential, 100 feet on collector
Residential - Residential 2 50 feet on both streets 50 feet on both streets
Flag Drive - Collector 1 20 feet on flag drive, 75 feet on collector 20 feet on flag drive, 100 feet on collector
Flag Drive - Residential 1 20 feet on flag drive, 50 feet on residential 20 feet on flag drive, 50 feet on residential
Alley - Collector 1 20 feet on alley, 75 feet on collector 20 feet on alley, 100 feet on collector
Alley - Residential 1 20 feet on alley, 50 feet on residential 20 feet on alley, 50 feet on residential
Alley - Alley 10 feet on both alleys 10 feet on both alleys
Notes:
[1] If permitted by the City’s Engineer.
[2] Driveways across T-intersections on residential streets are exempt.
3. Offset and relative to median openings (See Figures 5.12 and 5.13 below)
a. For collector streets, drive approaches that do not align across the street from each
other must be offset by a minimum of 75 feet between nearest tangent-edge to nearest
tangent-edge.
b. For arterial streets without medians, drive approaches must align across the street from
each other, and must be approved by the City’s Engineer. When this is not physically
possible or practical as determined by the City’s Engineer, drive approaches that do not
align must be offset across the street from each other by a minimum of 150 feet
between nearest tangent-edge to nearest tangent-edge.
c. For arterial streets with medians, drive approaches must align with existing or proposed
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5.5.2 Drives
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median openings. Where this is not possible or practical as determined by the City ’s
Engineer, drive approaches must be placed as far away from the existing or proposed
median opening as is reasonably possible.
Figure 5.12 Drive Approach Near Turning Movements
Figure 5.13 Drive Approach Near Turning Movements
C. Drive Approach Grades
1. Minimum Drive Approach Slope:
The minimum drive approach slope shall be determined by:
S = (6 + [0.02 x W x 12]) / (W x 12) [Eqn. 5.2]
Where: W = the width of the parkway in feet as shown on the City of Denton
Standard Details.
2. Maximum Drive Approach Slope: Unless otherwise approved by the City’s Engineer through
a design deviation request (Section 9), the maximum drive approach slope shall be 12%.
3. Difference in Drive Approach Grade: Driveway profiles shall not have a grade difference
greater than 5%, without constructing a vertical curve. A minimum K-value of 4 is
recommended for driveways accommodating low ground clearance or long wheelbase
vehicles.
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5.5.2 Drives
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4. Sidewalks in Drive Approach: Maximum sidewalk cross slope within the limits of the drive
approach shall be 2%.
5. Sidewalk Easement Requirement: Where the parkway width is insufficient to provide
appropriate drive approach slope, a sidewalk easement will be required, equal to the balance
of the sidewalk width needed outside the ROW plus two (2) feet. The additional two (2) feet
requirement is for sidewalk installation and maintenance. The balance of the sidewalk width
needed is based upon using the minimum drive approach slope calculated in Section
5.5.2.C.1 above. See Figure 5.14 below as well as City of Denton Standard Details.
6. Driveway/Drive Aisle Consideration: The drive approach slope from the bottom of the gutter
to the nearest edge of the sidewalk (within the limits of the ROW) shall not exceed the
driveway/drive aisle slope beginning at the furthermost edge of the sidewalk. Also, it shall
not be less than the minimum slope, nor be greater than the maximum slope as noted herein.
Figure 5.14 Sidewalk Easement to meet Drive Approach Slope
D. Driveway Throat Length Requirements
1. Minimum throat length requirements are shown in Table 5.5-D below. Note that throat
length requirement applies to both edges of the drive approach.
2. All drive approaches that access an arterial shall be classified as a primary drive approach. If
no drive approaches access an arterial, then the drive approach expected to receive the most
traffic is considered to be the primary drive approach.
3. The throat length is measured between the first parking space or drive aisle and the curb
line, whichever is closer to the curb line.
4. Parking lots with 10 or less parking spaces may use a minimum throat length of 10 feet for
drive approaches accessing a residential or collector street.
5. For gated entries, a minimum storage of 100 feet must be provided from the travel lane face
of the curb with an area for turnaround.
6. A queuing analysis shall be required for gated entrances and drive-throughs.
Section 5: Transportation Design Criteria
5.5 Auxiliary Roadway Design
5.5.2 Drives
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Table 5.5-D: Minimum Throat Length
No. of Parking Spaces Min. Throat Length for
Primary Drive Aisle (feet)
Min. Throat Length for
Secondary Drive Aisle (feet)
0 to 100 20 20
101 to 250 40 20
251 to 500 60 40
501 to 1000 80 60
1001 and above Queuing Analysis Required Queuing Analysis Required
E. Driveway Separation
Driveways shall be separated in accordance with Table 5.5-B to ensure that all driveways are
separated by sufficient distance so as to avoid interfering with the safe movement of traffic. In
interpreting and applying the separation requirements, the following shall apply:
1. The separation requirements shall be determined in reference to any proposed or existing
driveways on or off the property. Where applied to a property, which is located adjacent to
an undeveloped tract, the separation requirements shall account for the placement of future
driveways on the adjacent undeveloped property.
2. The minimum separation specified may be reduced for currently developed property, if the
amount of street frontage for the property is insufficient to allow for one (1) driveway access
that would have the necessary separation from an existing driveway on adjacent property,
and joint access with adjacent properties is not physically possible, as determined by the
City’s Engineer. If a reduction in the minimum separation specified is allowed, the separation
shall be reduced only to the degree necessary to allow for the single driveway.
F. Corner Clearance Standards
Corner clearance standards shall be applied in accordance with AASHTO “Green book” to ensure
that the traffic movements from driveways do not unduly conflict with the movement of traffic on
intersecting public streets. In interpreting and applying the corner clearance standards, the
following shall apply:
1. A reduced requirement may only be used if absolutely necessary to provide driveway access
to property where no other means of access meeting the corner clearance requirement is
reasonably possible, and joint access with adjacent properties is not physically possible as
determined by the City’s Engineer. If a reduction in the minimum corner clearance specified
is allowed, the corner clearance shall be reduced only to the degree necessary to allow for
the single driveway.
2. The specified distances shall be measured at the ROW line from the edge of the driveway
nearest the intersecting street to the ROW line of the intersecting street. Where ROW corner
clips exist or are proposed, the specified distance shall be measured from the edge of the
driveway nearest the intersecting street and the end of the corner clip nearest to the subject
driveway.
G. Modifications to Existing Drives
Existing non-compliant drives may be modified to comply with criteria set forth in this Manual, but
may not be modified in a way that increases the non-compliance with this Manual.
Section 5: Transportation Design Criteria
5.5 Auxiliary Roadway Design
5.5.3 Cul-de-sacs
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H. TxDOT Drives
All drives connecting to TxDOT roadways shall meet all required TxDOT standards, in addition to
meeting City of Denton standards when applicable.
5.5.3 Cul-de-sacs
A. Geometrical Standards
1. Maximum length of a Cul-de-sac shall be 600 feet measured from the centerline of the
intersecting street to the Cul-de-sac radius point, and perpendicular to the intersecting street
centerline.
2. Minimum length of a Cul-de-sac shall meet Fire Code requirements.
3. Residential Cul-de-sacs shall not have more than 29 residential lots.
4. The center radius of the Cul-de-sac shall be a minimum of 50 feet for residential
developments, and 60 feet for commercial and industrial developments measured from the
center point to the face of curb or edge of pavement where there is no curb.
5. The Cul-de-sac return radius shall be 30 feet.
6. Cul-de-sac minimum street grades shall be as shown below in Figure 5.15 and Figure 5.16
below for downward gradient and upward gradient, respectively.
Figure 5.15 Cul-de-sac Minimum Slope - Downward Gradient
Section 5: Transportation Design Criteria
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5.5.4 Hammerhead Turnarounds
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Figure 5.16 Cul-de-sac Minimum Slope - Upward Gradient
B. Offset Cul-de-sacs
1. Offset Cul-de-sacs shall have the same radius and return radius as the standard Cul-de-sac.
2. The length of the offset Cul-de-sac shall be measured from the centerline of the intersecting
street to the Cul-de-sac radius point, perpendicular to the intersecting street centerline.
C. Temporary Turn-Around
1. A temporary turn-around shall be limited to approved phase developments where the street
will be extended in the future.
2. A temporary turn-around shall meet the requirements of a standard Cul-de-sac for radius
and return radius size.
3. The length of street associated with the turn-around shall not be any greater than 600 feet
nor less than Fire Code requirements.
4. If the length of street will be greater than 600 feet, then the next block length of street and
intersecting streets shall be constructed in order to provide looped traffic flow for emergency
vehicles.
5. The turn-around section shall be constructed to the same structural section as the street
section less curb and gutter requirements, unless drainage requirements warrant curb and
gutter.
5.5.4 Hammerhead Turnarounds
A. The legs of the hammerhead (forming the “T” shape) should be at least 60 feet in length, measured
from the centerline of the intersecting roadway.
B. The turnaround must be constructed to support heavy vehicles and meet all width and corner radius
Section 5: Transportation Design Criteria
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5.5.5 Supplementary Design Elements
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standards required for emergency access.
C. No parking or obstructions are allowed within the hammerhead area to ensure full access for
emergency vehicles.
Figure 5.17 Hammerhead Turnarounds
5.5.5 Supplementary Design Elements
A. Signage and Striping
Signage and pavement markings shall be as shown in the Texas Manual on Uniform Traffic Control
Devices (TMUTCD).
1. New subdivisions must include STOP signs on minor street approaches and All-Way STOP
control (AWSC) where long stretches of Residential, Collector, and Arterial intersections.
(Determined by the reviewer or City’s Engineer) . The City’s Engineer must approve AWSC
signs.
2. Midblock crossings are discouraged; where it’s inevitable, it must have LED- Crosswalk Signs,
Ped warning, Ped crossing signs, Rectangular Rapid-Flashing Beacons (RRFBs), Pedestrian
Hybrid Beacons (PHBs), or other active crossing signs as directed by the City’s Engineer.
3. Crosswalk Markings - Continental style – Two (2) feet wide by 10 feet long white
thermoplastic
a. Crosswalks shall only be installed if there are Barrier-Free Ramps (BFRs) on both ends
of the road.
b. Crosswalks are required only on Collectors and above, not on residential, local streets,
or alleys.
4. ‘STOP’ Bars – 24 inches white thermoplastic located 2 inches from the crosswalk or aligned
with ‘STOP’ signs.
B. On-street Parking
Consistent with the requirements of Public Rights of Way Accessibility Guidelines (PROWAG), the
following Americans with Disabilities Act (ADA) on-street parking requirements shall be followed:
1. General
a. On-street parking is permitted for residential and residential collector streets, unless
prohibited by the City’s Engineer.
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b. On-street parking should be parallel, while angled and perpendicular parking requires
approval from the City’s Engineer.
c. On-street parking for proposed commercial/industrial collectors or arterials is not
allowed. Where on-street parking is designated, one (1) on-street parking space for
each single-family unit on a block is required on the frontage street within that block.
d. Areas in front of a driveway, within five (5) feet of a driveway, within 20 feet of a street
intersection, or within 15 feet of a fire hydrant shall not be counted toward the required
on-street parking.
2. Parallel Parking
a. For parallel parking spaces where the adjacent sidewalk or available ROW is more than
14 feet wide, an access aisle must be provided at street level for the entire length of
each accessible parallel parking space.
b. The access aisle must be a minimum of five (5) feet wide and connect to a pedestrian
access route.
c. The access aisle must not encroach on the vehicular travel lane and must comply with
the technical requirements for surfaces.
d. In alterations where the street or sidewalk adjacent to the parking spaces is not altered,
an access aisle is not required, provided the parking spaces are located at the end of
the block face.
e. Where the adjacent sidewalk or available ROW is less than or equal to 14 feet wide, an
access aisle is not required, but accessible parallel parking spaces must be located at
the end of the block face.
Figure 5.18 shows the acceptable parking configuration for on-street parallel parking.
Figure 5.18 Parallel Parking
3. Perpendicular and Angled Parking
a. For perpendicular and angled parking spaces, an access aisle must be provided at street
level for the entire length of each accessible perpendicular or angled parking space.
b. The access aisle must be a minimum of eight (8) feet wide to accommodate vans with
lifts and connect to a pedestrian access route.
c. Two (2) accessible parking spaces are permitted to share a common access aisle.
d. The access aisle must be marked to discourage parking in the aisle and comply with the
technical requirements for surfaces.
Figures 5.19 through 5.22 show the acceptable parking configurations for on-street
angled parking.
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5.5 Auxiliary Roadway Design
5.5.5 Supplementary Design Elements
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Figure 5.19 Angled Parking – 30 degrees
Figure 5.20 Angled Parking - 45 degrees
Figure 5.21 Angled Parking - 60 degrees
Section 5: Transportation Design Criteria
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5.5.5 Supplementary Design Elements
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Figure 5.22 Angled Parking - 90 degrees
4. Curb Ramps and Blended Transitions
a. Curb ramps and blended transitions must connect the access aisle serving each
accessible on-street parking space to the pedestrian access route.
b. Curb ramps are not permitted within the access aisle.
c. Parking spaces at the end of block face can be served by curb ramps or blended
transitions at the pedestrian street crossing.
d. Detectable warning surfaces are not required on curb ramps and blended transitions
that connect the access aisle to the sidewalk, including where the sidewalk is at the same
level as the parking spaces, unless the curb ramps and blended transitions also serve
pedestrian street crossings.
5. Other
a. Wheel stops will be required to prevent vehicle overhang into adjacent property, ROW,
structures, landscaping or sidewalk (applicable to ‘**’ shown on above figures).
b. Parking spaces may be reduced to 16.5 feet in length if a two (2) feet overhang is
provided.
c. All standard parking space striping shall be white in color.
d. On-street motorcycle parking space is half the size of a vehicle parking space.
C. Median Openings
Median openings for collectors and arterials shall be as designated by the City’s Engineer. Median
opening allowance shall primarily consider the safety and effective flow of traffic within the collector
or arterial street, then secondarily consider the effective movement of traffic to and from the
development. Whether a median opening is allowed will solely be up to the City’s Engineer.
When a development is allowed to have a median opening, it shall be provided in accordance with
the following criteria:
1. The width of a median opening shall be 60 feet.
2. Median openings shall center on the intersecting drive.
3. Median openings shall be a minimum of 400 feet apart, measured from nose-to-nose of
medians.
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5.5.5 Supplementary Design Elements
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4. Whenever a median opening is constructed, the associated left-turn lane serving the
development must be constructed at the same time. In the event that there is an existing
intersecting street on the opposite side of the street, the new development constructing the
median opening shall be required to install both left-turn lanes.
5. Patterned and colored median noses shall be constructed as shown on the City of Denton
Standard Details.
6. For any proposed median opening on TxDOT-maintained facilities, the standards outlined in
the TxDOT Roadway Design Manual shall be followed.
D. Traffic Calming
1. General Policy
a. Traffic calming measures intended to control vehicle speeds within the public ROW are
generally not permitted.
b. Exceptions may be considered in critical areas where documented overspeeding
presents a safety hazard - such as in front of schools, hospitals, parks, or other
pedestrian-sensitive environments.
c. Any installation within the public ROW must be supported by an engineering study that
documents operating speeds exceeding the posted limit and must receive approval by
the City Fire Code Official, ensuring compliance with the most current provisions of the
IFC adopted by the City.
2. Prohibited vs. Conditional Devices
a. Prohibited Devices:
i. Speed humps, bumps, and other similar vertical deflection devices are prohibited
on both public ROW and private property fire apparatus access roads.
These devices have been shown to delay emergency response times by
approximately 10 seconds per device and have been associated with damage to
fire and EMS vehicle frames as well as injuries to emergency personnel during
response operations. For these reasons, they are not permitted within the City.
b. Conditional Devices:
i. Speed cushions or segmented devices designed to allow emergency vehicle
clearance may be considered on private property only. These devices require City
Fire Code Official approval and must conform to current IFC standards and
applicable AASHTO/ITE traffic calming guidance.
ii. Horizontal traffic calming devices (including but not limited to chokers, chicanes,
traffic circles, and similar geometric modifications) may be considered on a case -
by-case basis within both public ROW and private property; however, their
implementation must be reviewed and approved by both the City’s Engineer and
the City Fire Code Official.
3. Design & Installation Standards
a. All traffic calming devices must include signage and pavement markings in compliance
with the most recent TMUTCD edition, where applicable.
b. Additional ROW dedication may be required to accommodate traffic calming devices
while maintaining minimum lane widths, drainage, and pedestrian or bicycle access.
Section 5: Transportation Design Criteria
5.6 Access Management
5.6.2 Purpose and Goals
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c. Devices must be constructed of durable materials (e.g., pre‑molded rubber, modular
plastic, or reinforced concrete) to ensure long‑term performance and maintain
emergency response accessibility.
4. Permitting Requirements
A separate permit is required to install any speed control device within a designated fire
apparatus access road.
5.6 Access Management
5.6.1 Purpose and Goals
The purpose of the access management plan is to promote the health, safety, and general welfare of the
present and future residents of the city through managing traffic flow and promoting traffic safety. In
planning and designing access for proposed developments, the following documents should be utilized in
conjunction with this section:
A. DDC Section 7.8.9 – Driveways and Access
B. DDC Section 7.8.10 – Cross-Access Between Abutting Developments
C. TxDOT Access Management Manual (if proposed access connects TxDOT-maintained facilities)
D. TxDOT Roadway Design Manual (if proposed access connects TxDOT-maintained facilities)
These standards collectively ensure safe, efficient, and coordinated access within the City’s roadway
network.
5.6.2 Access Standards
A. Compliance
1. No person shall construct, reconstruct, replace, relocate, alter, enlarge, improve or perform
any work on or make use of any driveway for any property within the City or its extraterritorial
jurisdiction, except in accordance with the Access Management standards provided in this
Manual or the TxDOT Access Management Manual, when applicable.
2. All driveways shall be designed, installed, located, and constructed in accordance with the
approved specifications, plans, conditions, and requirements of the permit issued for the
property, and the requirements of this Manual.
3. No certificate of occupancy shall be issued for any building on any property for which a
permit is required, until the construction, improvements, alterations or other work covered
by the permit is completed in accordance with the permit issued, the requirements of this
Manual, or the provisions of any other applicable ordinance.
4. Where no building permit was required in connection with the requested permit, no driveway
on the property for which the permit was issued shall be used until and unless the work is
completed in accordance with the permit, and this Manual.
B. Access to Freeways
Direct access from private property to freeway main lanes is prohibited. Access is provided
exclusively at designated interchanges and ramps. Access to adjacent frontage roads must comply
with the TxDOT Access Management Manual and are subject to the following provisions:
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5.6.2 Access Standards
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1. Control of Access:
Access is prohibited in areas where TxDOT has established Control of Access. Control of
Access areas are documented on current TxDOT ROW maps.
2. Direct Ramp Access:
a. Ramps with Frontage Roads: Direct access from adjacent properties or streets is strictly
prohibited for the entire length of the ramp.
b. Interstate Ramps without Frontage Roads or Interstate Interchange Connectors: Direct
access is prohibited along the full length of the ramp or connector in accordance with
23 CFR 625.3 and 625.4.
c. Non-Interstate Facilities without Frontage Roads: Direct access is strongly discouraged.
If allowed, the location must be determined based on spacing criteria and procedures
outlined in this Manual and the TxDOT Access Management Manual.
3. Frontage Road Considerations:
Direct access to frontage roads is prohibited in the vicinity of ramp connections to ensure
safe merging, weaving, and adequate acceleration and deceleration of vehicles.
4. Ramp Proximity Restrictions:
a. Exit Ramps: No access shall be permitted within the paved gore area or within 250 feet
downstream of the painted gore of an exit ramp.
b. Entrance Ramps: No access shall be permitted within the paved gore area or within 200
feet upstream of the painted gore of an entrance ramp.
c. For further guidance, refer to the TxDOT Roadway Design Manual.
5. Design Considerations:
The spacing of interchanges and ramps shall provide adequate distance for entering and
exiting vehicles to safely accelerate, decelerate, and weave, consistent with TxDOT design
standards.
C. Access to Arterial Streets
Access to an arterial street shall not be permitted unless there is no other reasonable means of
providing safe access to the property. Unless designated as a freeway, all TxDOT Highways shall
be considered arterials. Additionally, the geometric, hydraulic, and pavement designs of all access
driveways to TxDOT roadways must be reviewed by TxDOT to ensure compliance with their
standards.
1. No development shall be allowed access to an arterial street if property excluded from the
development could have been used to provide reasonable access to a lesser classified street,
or if the property has been previously subdivided in violation of state law or the DDC and if
access could have been provided to a lesser street except for such unapproved subdivision
of the property.
2. Existing commercial or industrial lots created prior to adoption of the DDC by legal
subdivision procedures with exclusive frontage on an arterial street may take access to the
arterial in accordance with the access standards in this Manual.
3. Existing single-family and duplex lots created prior to adoption of the DDC by legal
subdivision procedures with exclusive frontage on an arterial street may be developed with
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5.6.3 Fire Apparatus Access Roads
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a circular drive. Such drives shall be designed and constructed in accordance with standards
for circular drives provided in this Manual.
4. When drives access to an arterial street is the only reasonable means of providing safe and
adequate access to the property as determined by the City’s Engineer, the drive design,
number of drives, location and construction shall be in accordance with this Manual.
5. Drives on an arterial shall align with existing median openings, other driveways, and "T"
intersections, or be offset in accordance with this Manual.
D. Access to Collector Streets
1. Access to collector streets for commercial, office, or industrial development is required and
shall be designed and constructed in accordance with the standards provided in this Manual.
2. Single-family or duplex lots shall not be designed such that there is no other means of access
other than a collector street.
3. Existing single-family and duplex lots developed prior to approval of the DDC with exclusive
frontage on a collector street and no alley may be developed with a circular drive. Such
drives shall be designed and constructed in accordance with the standards for circular drives
provided in this Manual.
4. Drives on a collector street shall align with existing driveways and 'T' intersections on the
opposite side of the street, or shall be offset in accordance with this Manual.
5.6.3 Fire Apparatus Access Roads
A. Design Standards
The design of all fire apparatus access roads shall be submitted to the Fire Department for review
and shall not be constructed without prior authorization from the City Fire Code Official.
1. Fire apparatus access roads shall be constructed in accordance with the City of Denton
standards for the concrete pavement cross-section of a residential street.
2. They shall be designed for all-weather use and capable of supporting fire apparatus with a
load rating of up to 75,000 pounds.
3. Width, Clearance, and Setback
a. Minimum unobstructed width of 24 feet for buildings up to 30 feet in height, and 26
feet for buildings over 30 feet in height.
b. Minimum vertical clearance of 14 feet.
c. Setback from the building face shall be a minimum of 15 feet and maximum of 30 feet.
4. Fire apparatus access roads must have a minimum inside turning radius of 25 feet, and a
minimum outside turning radius of 45 feet.
a. Driveways less than 24 feet wide may have a minimum inside turning radius of 28 feet.
b. Driveways wider than 26 feet may have a minimum inside turning radius of 20 feet.
5. Maximum grade for fire apparatus access roads shall not exceed 10%.
6. Proximity to Buildings
Fire apparatus access roads shall be located so that all parts of the building are accessible
within 150 feet, measured along the hose lay from the lane.
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5.7 Bike and Pedestrian Facility Design
5.7.2 Mobility Plan Component
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For buildings fully equipped with an approved automatic fire suppression system, this
distance may be increased to 300 feet upon approval of the City Fire Code Official.
7. Dead-End Lanes must provide an IFC-approved turnaround if the dead-end exceeds 150 feet
in length (IFC Appendix D). Refer to Sections 5.5.3 and 5.5.4 of this manual for further details
regarding turnarounds.
8. Traffic Calming - No speed bumps or similar traffic calming devices are permitted in fire
apparatus access roads (IFC 503.4.1).
B. Modification of Existing Fire Apparatus Access Roads
Modification of existing fire apparatus access roads MUST be approved by the Fire Marshal's Office.
C. Marking
1. Striping
Fire apparatus access roads shall be marked by painting 6-in. wide red traffic lines at its
boundaries, as indicated on the plat. The words "NO PARKING FIRE LANE" or "FIRE LANE NO
PARKING" shall be four (4) inches high.
2. Signage
Signs shall read "NO PARKING FIRE LANE" or "FIRE LANE NO PARKING" and shall be 12 -in.
wide and 18-in. high. Signs shall be painted on a white background with letters and borders
in red, using not less than 2-in. high lettering. Signs shall be permanently affixed to a
stationary post, and the bottom of the sign shall be six (6) feet and six (6) inches or 6'-6"
above finished grade. Signs shall not be spaced more than 50 feet apart. Signs may be
installed on permanent buildings or walls, as approved by the Fire Marshal.
5.7 Bike and Pedestrian Facility Design
The user should be aware of and utilize the DDC Section 7.8.11 Pedestrian and Bicycle Circulation, in
conjunction with this section for the design of bike and pedestrian facilities.
5.7.1 Mobility Plan Component
The City of Denton Mobility Plan includes a pedestrian and bicycle component, which should be reviewed,
relative to any proposed transportation improvement.
It should be noted that the City of Denton Mobility Plan is a living document and is periodically updated to
reflect the changes in the characteristics of anticipated traffic flow within the City.
5.7.2 Accessibility Standards
The City of Denton considers sidewalks to be accessible routes according to Section 4.3 of Texas
Accessibility Standards (TAS) and considers a public sidewalk a “facility”. Sidewalks, landings, ramps, and
flares shall comply with the most recently adopted TAS, ADA, PROWAG, and FHWA standards. Also,
sidewalks, landings, ramps, and flares are subject to the requirements of the Texas Department of Licensing
and Registration (TDLR) for inspection purposes. Prior to construction of sidewalks, the Engineer of Record
must show proof of TDLR review and approval for accessibility, if the total cost of the public improvements
will exceed $50,000.00. Compliance with the regulations shall be the responsibility of the Engineer of Record
for the project. Refer to the City of Denton Standard Details for additional requirements.
Section 5: Transportation Design Criteria
5.7 Bike and Pedestrian Facility Design
5.7.3 Geometric Standards
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5.7.3 Geometric Standards
Table 5.7-A shows the standard width of sidewalks and bike lanes for the various roadway classifications.
Refer to the City of Denton Standard Details for the locations of sidewalks and bike lanes within the street
ROW. The Denton Mobility Plan should be reviewed for any planned bicycle and pedestrian facilities that
may exceed those called for by the standard details. Any portion of the proposed facility extending past the
ROW shall be contained within a pedestrian access easement. The recorded easement sh all extend two (2)
feet beyond the edge of the facility.
Table 5.7-A: Bike and Sidewalk Requirements
Roadway Classification Min. Sidewalk Width 1 Min. Bike Lane Width 1
Freeway N/A
Arterials – Primary and Secondary 5 10
Major Collector 8 10
Collector – Commercial and Residential 8 10
Local – Residential 5 N/A
Local – Rural N/A N/A
Local – Alley N/A N/A
Notes:
[1] Refer to the City of Denton Standard Details street cross-sections for specific bike and pedestrian recommendations.
[2] Sidewalks must be at least 6 inches away from the ROW line.
[3] Sidewalks must have green space/parkway between sidewalk and street curb per City Standard Details.
[4] If sidewalks are provided at the back of the curb, then the minimum width must be 6 feet.
[5] Inlet covers cannot be part of the sidewalk.
[6] Existing sidewalks that do not comply with ADA and City/Mobility Plan standards should be upgraded to meet current City, Mobility
Plan and ADA requirements.
[7] For sidewalks or other pedestrian facilities proposed in a TxDOT ROW, a TxDOT permit will be required to do any work.
A. On Bridges
Sidewalks on bridges shall be a minimum width of six (6) feet or wider, as required by the street
classification. All street bridges shall have sidewalks on both sides of the bridge. Dependent upon
vehicular and pedestrian traffic considerations, a parapet wall may be required to separate the
sidewalk from the travel lane. Parapet walls shall be constructed to TxDOT standards. A pedestrian
bridge rail shall be constructed on the outside of the bridge to protect sidewalk traffic. Both bridge
rails and parapet walls shall meet accessibility standards.
B. On Drainage Crossings
Sidewalk at drainage crossings shall be a minimum width of six (6) feet or wider as required by the
street classification. Sidewalk railing shall be provided to protect the sidewalk traffic from the
outside edge of the drainage crossing. Dependent upon vehicular and pedestrian traffic
considerations, a parapet wall may be required to separate the sidewalk from the travel lane.
Parapet walls shall be constructed to TxDOT standards. Railing and parapet walls shall meet
accessibility standards.
C. Adjacent to Screen Walls
A minimum additional sidewalk width of two (2) feet shall be required beyond the standard width
of sidewalk, for sidewalks adjacent to screen walls.
Section 5: Transportation Design Criteria
5.7 Bike and Pedestrian Facility Design
5.7.6 Intersection
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D. Adjacent to Retaining Walls
A minimum greenspace width of five (5) feet between the sidewalk and the edge of a retaining wall
shall be required, for sidewalks adjacent to retaining walls.
5.7.4 Intersection
A. Curb Ramps
The continuation of accessible routes through intersections shall use approved curb ramps that
meet accessibility standards. Refer to the City of Denton Standard Details for curb ramps at
intersections. Crosswalks through the intersections shall meet accessibility standards.
The following provisions further define requirements for sidewalk connections, proposed barrier-
free ramps (BFRs), and receiving BFRs to ensure continuity, safety, and full accessibility throughout
the intersection.
1. Sidewalks connecting to existing BFRs at intersections must be fully ADA-compliant.
2. Proposed BFRs at project corners must be aligned with existing or planned BFRs on the
opposite corners. Plans shall illustrate the full intersection layout, including all ramps and
crosswalks.
3. A receiving BFR is required in accordance with PROWAG standards for all new construction
and alterations to existing facilities. If no receiving ramp exists on the opposite side of the
intersection, a new receiving ramp with an appropriate landing must be constructed,
regardless of whether a sidewalk is present. Any exceptions from this requirement must be
approved by the City’s Engineer.
B. Bike Lanes
Bike lanes at intersections shall consider other traffic movements and facilities such as turn lane
movements, transit facilities, parking, and stop bar locations. The current Urban Intersection Design
Guide by TxDOT can be used for bike lane design at intersections. The bike lane design at
intersections requires the approval of the City’s Engineer.
5.7.5 Signage and Pavement Markings
Signage and pavement markings shall be as shown on the TMUTCD Marking & Sign Drawings, and in
accordance with the accessibility standards.
A. Crosswalks
Continental type-high visibility crosswalk markings are to be provided in all uncontrolled street
crossings, school crossings, downtown areas, or as directed by the City’s Engineer.
B. Bike Lane
Traffic control devices such as vertical flex posts, green pavement markings, and wayfinding signage
may be required to enhance the proposed bicycle facility, as directed by the City’s Engineer. For
additional guidance, refer to Section 5.5.5.A of this manual.
5.7.6 Amenities
A. Bike Parking
1. Refer to Bicycle Parking Guideline 2nd Edition by the Association of Pedestrian and Bicycle
Professionals (APBP) for general guidelines and resources.
Section 5: Transportation Design Criteria
5.7 Bike and Pedestrian Facility Design
5.7.6 Amenities
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2. All bicycle parking facilities/devices shall be constructed to meet commercial grade structural
standards.
3. Location Standard:
a. Bicycle parking must be on the same lot as the principal use.
b. Bicycle parking must be located in highly visible and well-lit areas.
c. Bicycle parking must not interfere with accessible paths of travel or accessible parking
as required by the accessibility standards.
d. Bicycle parking must be located within 50 feet of a main building entrance. In multiple
building locations, bicycle parking must be distributed in a manner that serves all
entrances.
4. Layout and Design:
a. Bicycle rack design:
i. Support the bicycle in at least two (2) places.
ii. Enable the frame and at least one (1) wheel to be secured.
iii. Designed to accommodate “U” shape locking devices.
iv. Installed to the manufacturer’s specifications.
v. Each bike rack must be designed to accommodate at least two (2) bikes.
vi. Each bike rack space should be a minimum of two (2) feet in width and six (6) feet
in length.
b. Bicycle Parking Space
i. Concrete pad built to City of Denton sidewalk standards.
ii. Must provide clearance of at least two (2) feet from closest wall.
iii. Must provide clearance of at least three (3) feet between bike racks.
iv. Must not interfere with pedestrian pathway.
In addition to selecting an appropriate bicycle rack type, the overall layout of bicycle parking areas
shall be designed to ensure safe, efficient, and accessible use. Minimum recommended dimensions
for bicycle rack areas are provided in the APBP Bicycle Parking Guidelines, as shown in Figure 5.23.
For larger bicycle parking areas with high turnover rates, multiple access points are recommended
to facilitate user circulation and reduce congestion. Where feasible, bicycle parking areas should be
oriented and designed to provide protection from weather elements, enhancing both usability and
longevity of the racks.
B. Benches
All benches shall be constructed to meet commercial-grade structural standards. Benches shall be
secured to prevent displacement. Benches shall not project into any accessible route or alter an
accessible route such that it will not meet the accessible route standards.
C. Lighting and Enclosures
Lighting standards and above-ground enclosures shall not extend into any accessible route or alter
an accessible route such that it will not meet the accessible route standards.
Section 5: Transportation Design Criteria
5.8 Transit Facility Design
5.8.1 General
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Figure 5.23 APBP-recommended design dimensions for bicycle rack areas
5.8 Transit Facility Design
5.8.1 General
Bus stops shall meet at a minimum the design standards of the Denton County Transit Authority (DCTA),
and the accessibility standards of TAS, PROWAG, and ADA. Figure 5.24 show a general layout of a bus stop
at an intersection. Bus stops shall be located on the departing side of a street intersection. The use of a pull-
out lane may be considered where the specific site conditions warrant such an arrangement. The
determination of the appropriateness of a pull -out lane shall rest with the City’s Engineer.
Figure 5.24 Standard Bus Stop Location at Unsignalized Intersection
Note: For signalized intersections an Approach Side Bus Stop is preferred
Section 5: Transportation Design Criteria
5.8 Transit Facility Design
5.8.3 Bus Stop Placement
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5.8.2 Bus Stop Placement
Bus stop placement should consider the need for the bus stop, traffic operation concerns, and passenger
accessibility. A bus stop should be placed within an area that allows bus stop amenities to be located in the
public ROW and where the ingress and egress of the bus does not overly impede the flow of traffic. The
warrant for a bus stop shall be as required by the City of Denton in conjunction with DCTA. Elements to
consider for bus stop placement include the following:
A. ADA and PROWAG compliance of all elements, including pedestrian routes, shelters, signing, etc .
B. Within Public ROW, or a dedicated access easement.
C. Proximity to major trip generators such as malls, student housing areas, retail commercial zones,
park and rides, destination areas, etc.
D. Pedestrian facilities such as sidewalks or multi-use paths, marked cross walks, space provisions for
accessibility standards, and curb ramps should be available at the location for a proposed bus stop.
E. Convenient passenger transfers to other routes.
F. Open and visible location for personal security and passenger visibility.
G. Acceptable street illumination or proposed street illumination with placement.
H. Ability to have restrictive parking in bus zone.
I. Adequate space for bus zone.
J. Gentle street grades at bus zone.
K. Return to traffic without overly hindering traffic flow.
L. No interference from driveways.
5.8.3 Bus Stop Amenities
The following are bus stop amenities that shall be considered during the process of design:
A. Accessibility compliant loading area. All bus stops shall have accessibility compliant loading and
offloading area. This area shall be integral to the sidewalk pathway, bench area, and shelter area, if
provided. The loading area shall be constructed of reinforced concrete with the same thickness as
the adjacent sidewalk.
B. Bench and trash receptacle may be warranted based upon Table 5.8-A. Bench and trash receptacle
type and installation shall be as required by the City of Denton.
C. A shelter may be warranted based upon Table 5.8-A The shelter type and installation shall be as
required by the City of Denton and DCTA. Shelters shall provide space to meet accessibility
standards.
D. Illumination shall be provided if illumination is not provided at the street corner adjacent to the bus
stop, or if in the opinion of the City’s Engineer the existing illumination is inadequate.
E. Bus stops that accumulate 10 points or more may be considered for shelter placement. Bus stops
that accumulate six (6) points or greater may warrant a bench and trash receptacle.
Section 5: Transportation Design Criteria
5.9 Traffic Impact Analysis Guidelines
5.9.2 Bus Stop Signage and Markings
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Table 5.8-A: Bus Stop Amenities Warrant
Points Condition
6 points 25 people per day boarding
4 points Special needs, i.e., Senior Center, Medical Complex, libraries, high accessibility
standard usage such as group residences
4 points High use location, i.e., Student housing area, schools, hospitals, mall
2 points Request for improvements by citizens, i.e., multiple requests over a one-year time
6 points 15 people per day or greater boarding
4 points Adjacent to an arterial roadway
5.8.4 Bus Stop Signage and Markings
Bus stop signage and markings shall be according to the City of Denton and DCTA. Signage shall include a
“No Parking Zone” sign and a DCTA bus stop sign.
5.9 Traffic Impact Analysis Guidelines
5.9.1 General
The purpose of the traffic impact analysis (TIA) is to assess the impacts of development on the existing
roadway system within the study area of the development and to assess the traffic flow needs within the
development. The thoroughfare component of the Mobility Plan and the City of Denton traffic model
establishes the base conditions for assessing the impacts. The current traffic model and the assessment is
based on a Level of Service D according to the current Highway Capacity Manual. The TIA shall be signed
and sealed by a licensed PE in the State of Texas, and shall be valid for a period of 3 years, unless there is a
significant change in the plans or surrounding conditions, as determined by City’s Engineer.
5.9.2 Trip Generation Assessment
A trip generation assessment shall be required for all proposed developments. Developers shall submit the
City-adopted Trip Generation Assessment Worksheet (“TGA Worksheet”) as part of Traffic Scoping submittal
process. Refer to City’s TIA Scoping Checklist. The TGA Worksheet must reflect unadjusted trip generation
projections for the proposed development, prepared in accordance with the following resources and
methodologies:
A. Trip forecasts shall be based on the most recent edition of the ITE Trip Generation Manual.
Developers shall utilize conservative trip estimates, specifically values falling between the Average
Rate and Fitted Curve Equation, where both are provided.
B. If an appropriate ITE Land Use Code is not available, applicants may submit empirical trip generation
data from comparable facilities of similar size and function within the Dallas–Fort Worth
metropolitan area. Supporting documentation must include a detailed description of the data
collection methodology, a demonstration of land use comparability, a description of site conditions,
and verification of data reliability. If alternative data sources are used, applicants must provide
justification and supporting documentation. All alternative data sources are subject to review and
approval by the City’s Engineer.
The City’s Engineer shall evaluate the TGA Worksheet, in combination with the thresholds and criteria
Section 5: Transportation Design Criteria
5.9 Traffic Impact Analysis Guidelines
5.9.4 When is a TIA required?
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specified in Section 5.9.3, to determine whether a TIA is required for the proposed development.
5.9.3 When is a TIA required?
Based on the TGA Worksheet for the proposed project, unless otherwise directed by the City ‘s Engineer, a
TIA will be required for the following conditions:
A. Development will generate equal to or more than 50 Peak-Hour Trips (PHT).
B. Development will generate equal to or more than 1,000 vehicle trips per day (VPD).
C. Project area to be developed is equal to or more than 100 acres.
D. Changes or alterations to the City Thoroughfare plan based on the Mobility Plan will be requested.
E. Access is taken from a TxDOT roadway, subject to both City and TxDOT TIA requirements.
F. Zoning changes that will negatively increase estimated traffic volumes above the current zoning
estimated traffic volumes.
G. Access is taken from an existing roadway with current traffic flow congestion based upon observed
conditions.
H. Development plus recently approved or pending development projects which have not been
constructed located adjacent to the site and/or in proximity to the site, meet the above vehicular
trip criteria or acreage criteria as determined by the City’s Engineer.
5.9.4 TIA Category and Study Area
Table 5.9-A shows the number of analysis periods and study area limits for TIAs.
Table 5.9-A: Criteria for Study Requirements
Analysis
Category
Site Trips
Generated at
Full Build-Out
TIA Analysis Periods 1 Minimum Study Area 3
I 50-99 total
peak hour trips
1. Existing year
2. Opening year 2
1. All site access drives
II 100‐500 total
peak hour trips
1. Existing year
2. Opening year 2
3. Five years after opening
1. All site access drives
2. All signalized intersections and/or major
unsignalized intersections within ½-mile
to 1 mile of site boundary, depending on
total peak hour trips
III >500 total
peak hour trips
1. Existing year
2. Opening year of each
phase
3. Five years after initial
opening
4. Twenty years after final
opening with full build‐out
1. All site access drives
2. All signalized intersections and/or major
unsignalized intersections within 1-½
miles of site boundary and/or major
intersections along access routes to/from
regional corridors
Notes:
[1] Analysis periods shall include build and no‑build scenarios. Assume full occupancy when each phase opens.
[2] Assume full build‑out.
[3] For certain projects, the City may require an enlarged study area. Land uses within the study area should include recently
approved or pending development adjacent to the site and/or in proximity to the site.
Section 5: Transportation Design Criteria
5.9 Traffic Impact Analysis Guidelines
5.9.5 TIA Scoping and Report
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5.9.5 TIA Scoping and Report
A. TIA Scoping
If a TIA is warranted for a development under the conditions outlined in Section 5.9.3, the
developers shall prepare and submit a TIA Scoping Memorandum in accordance with the City’s
most recently adopted TIA Scoping Checklist. The scoping process ensures consistency,
transparency, and effective coordination between the developers and the City. A TIA will not be
accepted for review without an approved TIA Scoping Memorandum.
The TIA Scoping Memorandum shall:
1. Establish the appropriate level of analysis for the proposed development (from Table 5.9-A);
2. Define study area boundaries and identify required intersections and roadway segments
(following Table 5.9-A);
3. Identify traffic data collection requirements and study periods (following Table 5.9 -A); and
4. Confirm the methodologies, assumptions, and evaluation tools to be applied in the study.
Refer to the City of Denton TIA Scoping Checklist for further details.
B. TIA Report
TIAs shall be prepared in accordance with the City of Denton TIA checklist, the approved TIA traffic
scoping, the Denton Development Code (DDC), and TxDOT standards, as applicable. At a minimum,
TIA reports shall address the following:
1. Project Description and Existing Conditions – Summarize the proposed development (land
use, size, location, phasing) and document existing roadway characteristics, intersection
control, traffic volumes, and any planned improvements within the defined study area.
2. Trip Generation, Distribution, and Future Conditions – Estimate trips per Section 5.9.2
methodology, assign them to the network, and evaluate traffic operations with and without
the project, considering background growth and approved developments.
3. Operational and Access Analysis – Assess performance of key intersections and roadway
segments (LOS, delay, v/c, queues), driveway spacing and sight distance, and internal
circulation. School developments shall include a Traffic Management Plan.
4. Multimodal and Safety Considerations – Identify pedestrian, bicycle, and transit impacts
along with any safety deficiencies.
5. Mitigation Strategy and Commitments – Identify operational or safety issues resulting from
the proposed development and recommend appropriate mitigation, such as turn lanes,
signal adjustments, intersection or geometric modifications, access management strategies,
or multimodal enhancements. Proposed improvements should be clearly categorized by
timing and responsibility, distinguishing between those required at opening day and those
that may be phased or coordinated with other developments or agencies. Recommendations
must form a practical implementation plan demonstrating how anticipated impacts will be
effectively addressed.
The City’s Engineer reserves the right to request additional data, analyses, or scenarios based on
project scope or site-specific conditions. Refer to the City of Denton TIA Checklist for detailed
formatting and submittal requirements.
Section 5: Transportation Design Criteria
5.9 Traffic Impact Analysis Guidelines
5.9.6 School Traffic Management Plan
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5.9.6 School Traffic Management Plan
A. Purpose
Schools generate atypical traffic conditions that require special consideration. They produce higher-
than-usual vehicular traffic, concentrated traffic loads at specific times, and a mix of different vehicle
types. Consequently, traffic management should be given the highest priority when evaluating new
school sites, upgrading existing sites, or reviewing ongoing school operations.
A School Traffic Management Plan (TMP) is a site-specific plan that addresses the school campus
and adjacent street network. It provides guidelines to coordinate traffic circulation during school
peak hours, ensuring that all road users are safely and efficiently guided through the site while
maintaining the performance of the roadway and minimizing impacts on surrounding properties.
B. Applicability
A TMP is required for:
1. Any new school development; or
2. Developments that are expected to significantly impact traffic operations at an existing
school.
The TMP must be prepared and submitted as part of the TIA to demonstrate that traffic conditions
at school access points have been adequately evaluated and mitigated.
C. TMP Preparation and Certification
1. The TMP shall be prepared by a licensed PE in the State of Texas with expertise in
transportation and traffic engineering, preferably certified as a Professional Traffic
Operations Engineer (PTOE).
2. Field observations of both morning drop-off and afternoon pick-up periods shall form the
basis of the TMP.
3. The TMP must be signed, stamped, and dated by the licensed PE and include a statement
confirming that it was developed with input from individuals familiar with the site’s traffic
characteristics, including contact information for the approving school administration official.
4. The TMP should be prepared in a format suitable for distribution to parents, students, and
school staff.
D. TMP Content Requirements
The TMP shall include, at a minimum, the following elements:
1. Site and Roadway Description
a. Location of the school site and description of adjacent roadways.
b. All points of vehicular and pedestrian access (ingress and egress).
2. TMP Exhibit
a. Scaled site diagram showing building footprints, curbs, pavement markings, parking
areas, and designated student drop-off and pick-up locations.
b. Aerial images are not acceptable due to replication challenges.
Section 5: Transportation Design Criteria
5.9 Traffic Impact Analysis Guidelines
5.9.7 Safety Assessment
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3. Traffic Operations
a. Summary table indicating school schedule, student enrollment by grade, maximum
vehicular accumulation, on-site storage capacity, and surplus during dismissal periods
or at designated loading zones.
b. On-site traffic circulation plan, including any temporary traffic control devices.
c. Proposed coordination system for student drop-off and pick-up (e.g., passenger
identification, separation of transportation modes, and staggered arrival/dismissal
times).
4. Staffing and Supervision
a. Number and location of school staff assisting with loading/unloading students, with
roles and responsibilities clearly defined.
b. Number and location of adult crossing guards or off-duty law enforcement personnel.
5. Pedestrian and Bicycle Considerations
a. Identification of pedestrian routes up to 0.5 miles from all school access points.
b. Strategies to encourage walking and biking.
6. Parking and Parent Communication
a. Parking management strategies for on-site and nearby public areas.
b. Communication plan to inform and engage parents, students, staff, and neighbors
regarding the TMP.
7. Additional Considerations (if applicable)
a. School bus loading and unloading operations.
b. Methodology for projected maximum vehicular accumulation.
c. Traffic control plan showing signage on public rights-of-way.
8. High-Speed Roadway Considerations: For schools adjacent to roadways with posted speed
limits of 35 mph or greater, the TMP shall include:
a. Turning movement counts at all major intersections adjacent to the school.
b. Stopping and intersection sight distances at all school driveway approaches.
5.9.7 Safety Assessment
Consistent with the recently adopted Mobility Plan, safety is the number one priority for the City of Denton
and as such, all new developments will be required to conduct a safety assessment as part of their TIA. The
safety assessment will include a review of safety for all road users (vehicles, pedestrians and bicycles) within
the project site as well as along existing public ROWs in the vicinity of the project. The assessment will
include a review of the following:
A. Within the project site (Site Circulation).
B. All new intersections including project driveways.
C. Evaluation of Historic Crash Data at all existing intersections and roadways included in the TIA.
Section 5: Transportation Design Criteria
5.10 Pavement Design Standard
5.10.1 Queue Analysis for Drive Through Facilities
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5.9.8 Queue Analysis for Drive Through Facilities
A review of proposed drive through operations must be included in the TIA. The evaluation must include:
A. Illustration of proposed operations (i.e. access points and queue formation).
B. Anticipated maximum demand/queue (preferably based on observations of other existing sites with
similar characteristics or using service rate queue analysis).
C. Maximum queuing capacity on-site.
D. Mitigation plan (Exhibit showing site plan) for if/when traffic ever exceeds design capacity to
prevent queues blocking sidewalks or travel lanes of adjacent roads. The plan needs to show how
the operator would have to manage longer queues without compromising safety (e.g. double
queue, cones, pavement markings, signs, etc.). The plan needs to be signed by the traffic engineer
whom the City would contact if/when needed to resolve back up problems once the tenant is in
operations - same as the traffic study.
E. The following information must also be included:
1. Peak hour turning movements at intersections with driveway during AM & PM peak hours
of adjacent street.
2. Average Daily Traffic on abutting street.
3. Show adjacent street traffic lane configuration, dedicated turning lanes, traffic control.
4. Site plan showing all dimensions of all driveways, sidewalks, crosswalks.
5.9.9 TIA Submission and Review Procedures
A. Trip Generation Assessment
The Trip Generation Assessment, as described in Section 5.9.2 of this Manual, must be completed
and submitted as Part A of Traffic Scoping submission to see if a TIA is required.
B. TIA Scoping
1. If a TIA is required (as determined in the TGA worksheet), or clearly warranted under
conditions in Section 5.9.3, TIA Scoping must be submitted following the direction provided
in section 5.9.4, 5.9.5.A & the City’s TIA Scoping Checklist Past B section.
2. The TIA scope must be reviewed and approved by the City prior to TIA application submittal.
C. TIA Report Submission
TIA Report Submission must follow Section 5.9.5.B and the City’s TIA checklist.
D. TIA Updates
If the development’s proposed land use or traffic generation characteristics change after TIA
approval, the TIA must be updated and resubmitted to the City for approval.
5.10 Pavement Design Standard
5.10.1 Streets
The minimum pavement section requirements for each classification of roadway are contained within the
City of Denton Standard Details for pavement cross-sections.
Section 5: Transportation Design Criteria
5.11 Complete and Context-Sensitive Streets
5.10.2 Drive Approach
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A. A geotechnical report shall be prepared that documents the existing soil characteristics of the
proposed roadway subgrade for any proposed street improvements. Soil testing shall be performed
whenever the soil characteristics change or every 500 feet, whichever is less. The report shall include
recommendations for the type and treatment level of subgrade stabilization based upon ultimate
traffic conditions.
B. Flex-base may be used as an option for subgrade treatment. Depth of flex-base required shall be
based upon the geotechnical report for the street improvements based upon ultimate traffic
conditions.
C. Alternative pavement sections may be proposed only if supported by a geotechnical report that
provides sufficient evidence to demonstrate that the alternate section shall meet the ultimate traffic
loading requirements.
5.10.2 Drive Approach
Refer to the City of Denton Standard Details for drive approach section requirements.
5.11 Complete and Context-Sensitive Streets
Complete streets are transportation facilities that are planned, designed, operated and maintained to
provide safe mobility for all users (including bicyclists, pedestrians, transit vehicles, truckers and motorists)
appropriate to the function and context of the facility. Context-sensitive solutions formulate a complete
street design considering contextual applications. Contextual applications can be of geographical nature
such as Urban Core, General Urban, Suburban, University Core and other typical service areas that require
unique components to address the overall transportation facilities.
Within the geometric standards are options that relate to developing a complete street that accounts for
all transportation facilities within the context of the associate area. Connectivity and context -sensitive
solutions are essential to meeting the goals of the standards. Refer to the City of Denton Standard Details
for cross-section details, and the pedestrian and bicycle components of the 2022 Mobility Plan for planned
facilities, or as required by the City of Denton during development review.
BIKE LANES – Bike lanes shall be six (6) feet wide unless otherwise approved by the City’s Engineer. Buffered
or separated bike lanes are generally preferred to increase level of comfort in the bicycle facility.
OFF-STREET MULTI-USE PATH – Some development areas will warrant the use of off-street multi-use
paths for pedestrian and bicycle traffic connectivity to other facilities as identified by the City of Denton.
Multi-use paths shall be 10 feet wide, unless otherwise approved by the City’s Engineer.
TRANSIT – Bus stop locations may be required by the City of Denton for connectivity of the transit system.
See Section 5.8 of this Manual for details.
MEDIAN VS. CONTINOUS LEFT TURN LANE – Selection of a median or continuous left turn lane shall be
based upon the TIA, connectivity, adjacent uses, and other factors required by the City’s Engineer. Medians
shall be 24 feet back of curb to back of curb, unless otherwise approved by the City’s Engineer. Continuous
left turn lanes shall be 11 feet wide.
MODIFICATIONS TO STANDARDS – Modifications to the standards may have to be considered in some
instances based upon context-sensitive use. An example of context-sensitive use which may require the
standards to be modified is a roadway corridor restriction that creates limitations that cannot be altered.
An example of a roadway corridor restrictions would be existing infrastructure and/or buildings that must
Section 5: Transportation Design Criteria
5.11 Complete and Context-Sensitive Streets
5.10.2 Drive Approach
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remain. Another example is infill development. Modifications to the standards based upon context-sensitive
use shall be at the sole discretion of the City’s Engineer.
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Section 6: Water and Wastewater Design
Criteria
6.1 Overview
The purpose of Section 6 - Water and Wastewater Design Criteria is to provide minimum, non-exhaustive
criteria for the design and construction of water distribution and wastewater collection systems within the
City of Denton, Texas and its extraterritorial jurisdictions.
It is the responsibility of the design engineer to ensure the final design of water distribution and wastewater
collection systems are in conformance with the most recently adopted versions of the following documents:
A. Texas Administrative Code (TAC) Title 30, Part 1, TCEQ – Ch. 290;
B. Texas Administrative Code (TAC) Title 30, Part 1, TCEQ – Ch. 217;
C. Texas Administrative Code (TAC) Title 16, Part 2, PUCT – Ch. 24;
D. City of Denton Code of Ordinances and the DDC;
E. The City of Denton’s Standard Details and Standard Specifications for Construction;
F. City of Denton Water Distribution System Master Plan ;
G. City of Denton Wastewater Master Plan;
H. American Water Works Association (AWWA) Standards;
I. The International Building Code (IBC);
J. The International Plumbing Code (IPC);
K. The International Fire Code (IFC); and
L. This Manual.
The criteria established in Section 6 of this Manual provide basic guidance for the design of water and
wastewater systems. However, full responsibility and liability for proper design remains with the design
engineer. Users of this Manual should be knowledgeable and experienced in the theory and application of
water and wastewater engineering. If criteria established in Section 6 overlap with state statutes, rules, or
regulations, the more stringent requirement shall apply. The criteria established in this Section do not
supersede the criteria contained in the DDC. In the case of conflict between this Section, City of Denton
Standard Details, or other cited City regulations and standards, the more stringent requirement shall apply.
The General Manager of Water Utilities and Street Operations reserves the right to require extended review,
direct the design, location specifications and details of vertical water utility infrastructure, and large
horizontal infrastructure including, but not limited to, water treatment plants (WTPs), elevated storage tanks
(ESTs), booster pump stations, water mains 16 inches in diameter or greater, wastewater reclamation plants,
peak flow detention facilities, sewer lift stations and sewer interceptors over 12 inches in diameter. The
General Manager of Water Utilities and Street Operations reserves the right to deny proposals at their
discretion.
6.1.1 Organization
Section 6 - Water and Wastewater Design Criteria is organized as follows:
Section 6: Water and Wastewater Design Criteria
6.2 Water Design Criteria
6.2.1 Distribution System Extensions
Design Criteria Manuals 129
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A. Overview
B. Water Design Criteria
C. Wastewater Design Criteria
D. Construction Plans
6.2 Water Design Criteria
6.2.1 Distribution System Extensions
A. General
Water mains shall be sized to meet the calculated water demand, fire flow protection requirements,
and to conform to the City of Denton’s Water Distribution System Master Plan (Water Master Plan
or WMP). All residential, commercial, industrial, and any other development connecting to the
City’s water distribution system shall use the following guidelines:
1. The design engineer shall obtain the record drawing water maps from the Capital
Improvement Projects & Engineering Division and use the following criteria, based on the
City’s WMP, for sizing the water lines.
a. Average daily demand in gallons per capita per day = 160 GPCD
b. Maximum daily demand / Average daily demand = 2.0
c. Peak hour demand / Maximum daily demand = 1.5
d. For Single-Family Residential – Use 3.2 people/unit
e. For Multifamily Residential – Use 2.5 people/unit
f. Refer to 30 TAC § 290.45 (d)(1) Table A - Non-community water systems
2. Water distribution systems extensions shall provide sufficient connections to the City’s
existing water system, integrating existing main extensions to the development (including
dead-end mains) from adjacent properties to the system extension, for the demand of the
proposed extension and shall be extended to neighboring properties for subsequent system
extensions. System extensions shall be of sufficient size to furnish adequate domestic,
irrigation, and fire protection water supply to all lots within the development and conform
to the City WMP. Every new water system extension shall include two (2) or more connections
to the existing City water system when feasible, to ensure an adequate and reliable water
supply in the event of a water main break or routine system maintenance. The City may
require two (2) or more meter connections, particularly for large and/or densely developed
lots. Good engineering judgement is required to ensure reliability is considered in the design
of all proposed water systems
3. Every development shall provide adequate water capacity for fire protection purposes. Fire
flow capacity requirements are in addition to daily demand requirements. The procedure for
determining fire flow requirements for buildings or portions of buildings shall be in
accordance with the version of the IFC adopted by the City. For any platted lot where the
end use is not defined, the standards in Table 6.2-A shall apply
4. The cost for modeling a project’s impact with the City’s distribution system model will be the
responsibility of the developer and paid to the City.
Section 6: Water and Wastewater Design Criteria
6.2 Water Design Criteria
6.2.1 Distribution System Extensions
Design Criteria Manuals 130
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B. Distribution System Operational Limits
The City observes the following operational limits for the distribution system under normal usage:
1. Maximum velocity for mains (greater than 16 inches): 3 fps, with up to 5 fps on case-by-case
basis
2. Maximum velocity for mains (16 inches or less) under non-fire flow conditions: 5 fps
3. Maximum velocity for mains (12 inches or less) under maximum day demand + fire flow
scenario: 10 fps
4. Maximum head loss (12 inches or less): 5 feet per 1,000 feet
5. Maximum head loss (16 inches or more): 3 feet per 1,000 feet
6. Hazen-Williams Roughness Coefficient (C): 130
Proposed impacts to the City’s system determined to, or likely to, cause (through hydraulic
modeling or other analysis) these limits to be exceeded, are prohibited without additional
improvements to the public system to allow proper operation of the system.
Table 6.2-A: Water Capacity for Fire Flow
Area GPM
One (1) and two (2) family dwellings - less than 3,600 sq. ft. 1,000
Buildings other than one (1) and two (2) family dwellings - less than 3,600 sq. ft. 1,500
Medium-intensity commercial and light industrial 3,000
High-intensity commercial and industrial 4,000
Notes:
[1] All fire flows to be calculated with 20 psi residual pressures.
[2] In addition to the fire flow requirements specified above, all developments shall provide adequate water capacity
to satisfy the greater of: (a) Peak Hour demand for the Peak Day, or (b) Average Hour demand plus fire flow for the
Peak Day.
[3] Special exceptions to the above standards may be made by the City’s Engineer for unique situations.
C. Public Fire Hydrants
Fire flow requirements shall be in accordance with the IFC as adopted by the City of Denton or
Denton County, as appropriate.
D. Private Fire Mains
In addition to the requirements of Section 6.2.1.B of this Manual above, private fire protection water
mains shall be installed in accordance with NFPA 24 and the adopted IFC requirements. Private fire
protection mains and associated hydrants shall be permitted by the Fire Marshal’s Office with
jurisdiction.
E. Fire Flow Tests
Fire flow tests are normally requested by the design engineer, the Mechanical, Electrical and
Plumbing (MEP) engineer, and other engineers to determine available water system capacity at or
near the point of interest. If a fire flow test on the existing water system is necessary, contact Water
Distribution at FireFlowTesting@cityofdenton.com.
F. Pressure Planes
The City of Denton’s Water Distribution System is divided into several water pressure planes to
Section 6: Water and Wastewater Design Criteria
6.2 Water Design Criteria
6.2.1 Distribution System Extensions
Design Criteria Manuals 131
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ensure even water-pressure gradients. Prior to the design of connection points between a
proposed main and any existing main, the design engineer shall investigate and determine if the
proposed water main crosses the boundary between different pressure planes.
Even though physical connections of water pipes exist between pressure planes, they are designed
with valves which are closed at the boundary points so that each pressure planes is isolated.
Proposed mains that approach pressure planes boundaries shall be designed to loop within their
designated pressure planes and with no or minimum lengths of dead-end mains.
Connections between pressure planes must be approved by the City’s Engineer and may require
pressure-reducing valve stations. The design engineer can determine the pressure planes
boundaries by consulting the record drawings which show the designated closed valves between
pressure planes and by contacting Water Utilities. See Figure 6.1 below for the 2025 Water System
Pressure Plane Map.
The Central pressure plane operates at a Hydraulic Grade Line (HGL) of 826 feet and includes service
elevations between 540 feet and 700 feet. It is recommended that any areas above 700 feet be
served from the West pressure plane, if possible. An alternative to connecting new development to
the higher-pressure plane includes grading sites to be below 700 feet. Areas at elevations below
600 feet may experience high pressure. Individual Pressure Reduction Valves (PRVs) may be needed
to maintain an acceptable pressure range.
Eastern pressure planes (i.e. East and Southeast) have a HGL of 745 feet are supplied from the
Central pressure plan by reducing pressure via system pressure-reduction valves. Service elevations
for the eastern pressure planes range from 515 feet and 615 feet.
The West pressure plane operates at an HGL of 900 feet at the Northwest EST, 905 feet at the
Southwest EST and includes service elevations between 670 feet and 770 feet. The boundary
between the West and Central pressure plane generally follows the 670-foot contour. Any areas at
elevations greater than 770 feet will not be able to be served by the existing distribution system
due to low static pressures. Areas near the suction side of the Southwest Boost Pump Station should
be served from the West pressure plane due to the decreased residual pressure in the Central
pressure plane in this area.
Section 6: Water and Wastewater Design Criteria
6.2 Water Design Criteria
6.2.1 Distribution System Extensions
Design Criteria Manuals 132
Published: January 2026 Go to Table of Contents
Figure 6.1 2025 Water Master Plan Pressure Plane Map
Section 6: Water and Wastewater Design Criteria
6.2 Water Design Criteria
6.2.4 Water Main Horizontal and Vertical Alignment
Design Criteria Manuals 133
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6.2.2 Water Main Horizontal and Vertical Alignment
The following guidelines should be followed by the design engineer in placement of water lines:
A. In existing streets, water lines shall be placed in the pavement four (4) feet from back of curb. For
new residential development, water lines shall be placed on the north and east sides of the streets,
where possible, four (4) feet from back of curb. See the City of Denton Standard Details.
B. All water lines shall be laid as straight as possible. Avoid excessive number of high points and low
points between cross street connections, as they trap air pockets. See Section 6.2.6.B of this Manual
for placement of air release valves.
C. Minimum radius of curvature and maximum deflection angle of pipe joints are restricted to the
manufacturer’s recommendation, after which, horizontal or vertical bends are required. Deflection
of pipe shall only be permitted through joint deflection; no bending of pipe is allowed.
D. Vertical bends shall be no greater than 45 degrees.
E. Except for transverse pipe crossings, no other utility shall be installed over, under or within five (5)
feet horizontally of a water line.
F. There shall be at least two (2) feet of vertical separation between a water line and any utility or
storm drain crossing it.
G. Water lines shall not be located closer than 10 feet to any building or structure, or located where
the excavation of which could place the stability of another structure in jeopardy.
H. Where distribution mains run parallel to transmission mains 16 inches or larger, a non-standard
cross-section detail will need to be coordinated with the Water Utility and accommodate the ROW
width, gravity and pressurized wastewater mains, reuse water mains and storm drainage mains.
I. The WMP is a guide for transmission main alignment and subject to formal and informal updates.
6.2.3 Depth of Cover for Water Mains
The following table shall govern depth of cover for water main installations:
Table 6.2-B: Minimum Depth of Cover for Water Mains
Pipe Size From Surface to Top of Pipe
UNDER UNPAVED AREAS UNDER PROPOSED OR EXISTING PAVEMENT
12-in. and smaller 5 feet 42 inches
16-in. - 5 feet
16-in. and larger 6 feet -
20-in. and larger - 6 feet
Notes:
[1] Additional depth of cover shall be required for low-lying areas where future drainage improvements are anticipated.
6.2.4 Pipe and Fittings
A. Specifying the appropriate pipe material is the responsibility of the design engineer, based on the
analysis of specific site and loading conditions, and pressure requirements. The minimum
requirements in this Section are based on pipe size only, and in no way relieve the design engineer
Section 6: Water and Wastewater Design Criteria
6.2 Water Design Criteria
6.2.4 Pipe and Fittings
Design Criteria Manuals 134
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of the responsibility of specifying the pipe material applicable to the specific project. Pipe gasket
material shall be that recommended by the manufacturer for the specified pipe. Special attention
shall be given by the design engineer for unique pipe fitting and pipe assembly situations.
B. Water pipe shall be a minimum of eight (8) inches in diameter. The standard pipe sizes that shall
be used for water main lines are 8-in., 12-in., 16-in., 20-in., 24-in., 30-in., 36-in., and 42-in. pipes.
Pipe sizes of 6-in., 10-in., 14-in., 18-in., 21-in., and 33-in. are considered non-standard by the City
and may not be used for water main lines. A 6-in. pipe may be used for fire hydrant connections.
C. Water mains 16 inches and greater in diameter shall have preplanned points of connection of no
less than 12 inches in diameter for distribution extensions. Tees with branch valves shall be used
for preplanned connections.
D. See Table 6.2-C below for the City’s minimum pipe materials, fittings, polywrap, thrust restraint, and
embedment requirements, as a function of pipe size.
E. All fittings for pipe sizes less than 30 inches in diameter, including vertical and horizontal bends,
shall have concrete thrust blocking. See City of Denton Standard Details.
F. All vertical and horizontal fittings and valves shall require restrained joints in addition to concrete
thrust blocking. The joint restraints shall be designed as though there is no concrete thrust blocking,
and the concrete thrust blocking shall be designed as though there are no joint restraints. Flanged
tees should be used to secure all branch valves to fittings. Table 6.2-C below includes the minimum
lengths of pipe to be restrained for 8 -inch and 12-inch PVC water mains. For water lines greater
than 12 inches in diameter, additional restrained joints may need to be installed beyond the fitting
(i.e., may need to be installed on several pipe joints on each side of the fitting), depending on the
required restrained length calculated. Restrained length calculations shall be i ncluded in the lay
schedule in the material submittal package and shall use approved methods of joint restraint. See
City of Denton Standard Details, specific product listings and Table 6.2-C below.
G. Geotechnical reports detailing soil conditions, that may affect the design, operation , or
maintenance of water infrastructure are required. Corresponding corrosion protection systems are
to be provided for metallic pipe materials including reports detailing the operation and
maintenance of the corrosion protection systems. Corrosion system design reports must be
included with record drawings.
Table 6.2-C: Restraint Lengths for Fittings and Bends
Pipe Size
(inches)
Plugs, Tees, and
Valves 1 Bends 1
90° 45° 22.5° 11.25°
8 88 ft 33 ft 14 ft 7 ft 4 ft
12 126 ft 45 ft 19 ft 9 ft 5 ft
Notes:
[1] Length to be restrained on each side of the bend or fitting. Assumptions: 1.5 safety factor, SP soil type, Type 4 trench.
Section 6: Water and Wastewater Design Criteria
6.2 Water Design Criteria
6.2.4 Pipe and Fittings
Design Criteria Manuals 135
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Table 6.2-D: Minimum Requirements for Pipe and Fittings
Pipe Size and Material Ductile Iron
Fittings
Corrosion
Protection Thrust Restraint Embedment
8-IN. TO 12-IN.
PVC
(AWWA C900, DR – 14)
Mechanical
joint;
Compact or
Full-Body
8-mil V-Bio
Enhanced Polywrap
(fitting only)
Wedge-action mechanical joint
restraint glands, at fittings.
See drawings U201,
U202, U203A,
U203C in
City of Denton
Standard Details
16-IN. TO 20-IN.
Ductile Iron,
AWWA C151,
Special Thickness Class 52,
push-on-joints
(where unrestrained;
e.g.: American Flex-Ring
joint)
Mechanical
joint;
Full-Body
8-mil V-Bio
Enhanced Polywrap
(inner layer), plus 4-
mil cross-linked
(outer layer) Bonded
joint and Cathodic
Protection (CP)
System required
Wedge-action mechanical joint
restraint glands, at fittings.
Boltless Restrained connections
(Example: American Flex-Ring
joint), at several pipe joints
either side of each fitting,
depending on the required
restrained length calculated.
See drawings U201,
U202, U203A,
U203C in
City of Denton
Standard Details
Reinforced Concrete Steel
Cylinder,
AWWA C303 Bar Wrapped
N/A Bonded joint and
Cathodic Protection
(CP) System required
Full Circle Welded Joints
required for thrust restraint
Contact Water
Utilities Dept.
24-IN.
Ductile Iron,
AWWA C151, Special
Thickness Class 52,
push-on joints
(where unrestrained;
e.g.: American Flex-Ring
joint)
Mechanical
joint;
Full-Body
8-mil V-Bio
Enhanced Polywrap
(inner layer), plus 4-
mil cross-linked
(outer layer) Bonded
joint and Cathodic
Protection (CP)
System required
Wedge-action mechanical joint
restraint glands, at fittings.
Boltless Restrained connections
(Example: American Flex-Ring
joint), at several pipe joints
either side of each fitting,
depending on the required
restrained length calculated.
Crushed Stone
Reinforced Concrete Steel
Cylinder,
AWWA C303 Bar Wrapped
N/A Bonded joint and
Cathodic Protection
(CP) System required
Full Circle Welded Joints
required for thrust restraint.
Contact Water
Utilities Dept.
30-IN. AND LARGER
Ductile Iron,
Pressure Class 350;
push-on joints
(where unrestrained; e.g.:
American Flex-Ring joint)
Mechanical
joint;
Full-Body
8-mil V-Bio
Enhanced Polywrap
(inner layer), plus 4-
mil cross-linked
(outer layer) Bonded
joint and Cathodic
Protection (CP)
System required
Wedge-action mechanical joint
restraint glands, at fittings.
Boltless Restrained connections
(Example: American Flex-Ring
joint), at several pipe joints
either side of each fitting,
depending on the required
restrained length calculated.
Crushed Stone
Reinforced Concrete Steel
Cylinder,
AWWA C303 Bar Wrapped
N/A Bonded joint and
Cathodic Protection
(CP) System required
Full Circle Welded Joints
required for thrust restraint.
Contact Water
Utilities Dept.
Section 6: Water and Wastewater Design Criteria
6.2 Water Design Criteria
6.2.6 Connections
Design Criteria Manuals 136
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6.2.5 Connections
A. Methods of Connection
1. Tapping Sleeve and Valve
Tapping sleeves with tapping valves shall be used whenever possible for connections to
existing mains to avoid interruption of water services. See Figure 3.1 in Drawing PIAZ13 of
the City of Denton Standard Details.
a. As per AWWA C223, size-on-size taps are allowed up to 12 inches (e.g.: 12-in. x 12-in.)
b. Taps on pipes 16 inches and larger must be approved in writing in advance by the City’s
Engineer after demonstrating the demand is greater than the availability from the
distribution existing system. Taps to mains 16 inches and greater must be a minimum
of 12 inches and utilize an isolation valve of the same size as the tap. Extensions may be
reduced by fittings after the tapping valve. See Figure 3.2 in Drawing PIAZ13 of the City
of Denton Standard Details.
c. Connections to fire hydrant leads on existing mains 16 inches and larger may be allowed
on a case-by-case basis after consultation and written approval by the City’s Engineer.
d. All water service lines, two (2) inches and smaller, require taps as per City of Denton
Standard Details.
2. Cut-in Connection
Cut-in connections are only allowed to existing mains larger than 12 inches, where a size -
on-size connection is needed. See Figure 3.4 in Drawing PIAZ14 of the City of Denton
Standard Details.
3. Main Extensions
A new valve shall be installed at the point of connection for water main extensions. This will
facilitate the testing and chlorination of the new main prior to its placement into service. See
Figure 3.5 in Drawing PIAZ14 the City of Denton Standard Details.
Note that the developer is responsible for all surface rehabilitation associated with
connecting to the City’s Water Utilities. Surface rehabilitation must match existing site
conditions or better.
B. Flushing and Disinfection
Refer to all current City specifications and TCEQ requirements for Flushing and Disinfection.
6.2.6 Valves
A. Isolation Valves
1. Location
Isolation valves shall be provided to allow for the proper operation and maintenance of the
water distribution system, and to ensure water quality can be maintained for each individual
water customer connected to the system.
The location of valves needs to properly address the ability of the Department of Water
Utilities to remove a water line from service to perform necessary repairs, while critically
minimizing the interruption of service for fire protection and to customers. Isolation of any
given section of water line should generally be able to be accomplished by closure of the
Section 6: Water and Wastewater Design Criteria
6.2 Water Design Criteria
6.2.6 Valves
Design Criteria Manuals 137
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least number of valves, as would generally be expected under good engineering design
practices and utility engineering standards. The Department of Water Utilities reserves the
right to require changes to proposed designs to satisfy these objectives.
The design engineer shall place valves on proposed water mains so they may be easily
located in the future by operations and maintenance crews.
The following guidelines should be used by the design engineer in placement of isolation
valves on proposed water mains:
a. Two (2) valves are to be installed at every main branch tee location, one (1) flanged to
the branch of the tee and the other a mechanical joint connection on one (1) of the two
(2) runs of the tee. See Figure 3.6 in Drawing PIAZ15 of the City of Denton Standard
Details. Three (3) valves are to be installed at every cross location, each a mechanical
joint connection.
b. Valves for line sizes 12 inches in diameter or less should not be spaced any farther apart
than 1,000 feet. For city blocks that are longer than 1,000 feet between street
intersections, placement of a valve will be required between street intersections.
c. Valves should be generally located so that no more than four (4) valves are required to
isolate a section of main. See Figure 3.7 in Drawing PIAZ15 of the City of Denton
Standard Details. For mains larger than 12 inches in diameter, valve spacing and
placement shall be subject to alternate criteria approved by the City’s Engineer.
d. All fire hydrant leads must be designed with a valve that is flanged to the main line. See
Drawings W401A and W401B of the City of Denton Standard Details.
2. Specifications
Refer to Table 6.2-L and Standard Specifications 33 14 20 Resilient Seated (Wedge) Gate
Valves and 33 14 21 AWWA Rubber-Seated Butterfly Valves.
Table 6.2-E: Isolation Valve Requirements
Size 4-in. to 12-in. 16-in. to 20-in. 24-in. 30-in. 36-in. or larger
Type Gate Valve
(AWWA C509
resilient-seat)
Gate Valve
(AWWA C515
resilient-seat)
Gate Valve
(AWWA C515
resilient-seat)
Gate Valve
(AWWA C515
resilient-seat)
Gate Valve
(AWWA C515 resilient-
seat) or butterfly, to be
determined by City on a
case-by-case basis
Orientation Vertical Vertical Vertical Vertical or horizontal;
to be determined
by City on a
case-by-case basis
Vertical or horizontal; to
be determined by City
on a
case-by-case basis
Gear
Operator
Required
No No Yes Yes Yes
Vault
Required
No No Yes Yes Yes
Bypass
Required
No No No Yes Yes
Section 6: Water and Wastewater Design Criteria
6.2 Water Design Criteria
6.2.7 Dead-End Mains
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3. Details
Refer to Drawings W104, W105, W106A, W106B, and W601 of the City of Denton Standard
Details.
B. Air Release Valves and Air/Vacuum-Air Release Valves
For water mains less than 16 inches in diameter in certain situations where the topography,
remoteness, or some other hydraulic factor necessitates it, air release valves are required at local
high points to facilitate automatic release of accumulated air.
For water mains 16 inches and larger, the City requires air/vacuum-air release valves at local high
points to facilitate automatic release of accumulated air and to facilitate automatic prevention of
vacuum conditions within the line. See Drawings W801 and W802 of the City Standard Details.
Manholes shall not be placed in sidewalks, pedestrian ramps, driveway approaches, or in the bottom
or on the slopes of a drainage channel or drainage structure. Manholes shall be kept a minimum of
40 feet from any railroad track.
C. Pressure Reduction Valves and Pressure Sustaining Valves
Public pressure reduction valves and pressure sustaining valves are to be coordinated with and
written approval obtained from the City’s Engineer in consultation with the Field Operations
division. Valves shall be located where they are accessible to City staff and located in a vault sized
for the valve assemblies and staff access in unpaved areas of ROW and/or PUE. PUEs shall be sized
considering the size of the vaults, depth of the water main, and site constraints, including, but not
limited to, highways, creeks, railroads, existing and proposed structures, ingress and egress
availability, topography, and ESAs.
D. Blowoff Valve Assemblies
Water mains 16 inches and larger shall be equipped with blowoff valve assemblies sized to facilitate
three (3) fps scouring velocities within the main, flushing and draining of the water main for
maintenance. Assemblies are to be located at low points where sediment can accumulate and to
ensure complete drainage of the main to allow for repairs to be completed on empty mains.
The discharge piping of the blowoff assembly must direct flushed water towards drainage
infrastructure without causing flooding. Erosion prevention must be included in the design of the
assembly and direction of discharged water. The location of the assemblies must be in a public
ROW or utility easement in an unpaved area large enough for operation of the assembly.
6.2.7 Dead-End Mains
A. Dead-end main situations should be avoided whenever possible, except for main extensions to
neighboring property for future extension.
B. In lieu of dead-end mains, the design should loop through public ROW or a dedicated public utility
easement (with adequate assurance of access and fencing prohibited) to another nearby water main
using the same size pipe.
C. If a dead-end main situation is unavoidable, it shall be designed so that it may be periodically
flushed of stagnant water by locating a fire hydrant or other flushing device near the main’s end
and past the last service connection. See City of Denton Standard Detail W603.
Section 6: Water and Wastewater Design Criteria
6.2 Water Design Criteria
6.2.9 Fire Hydrant Locations and Coverage
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6.2.8 Fire Hydrant Locations and Coverage
A. The design engineer should locate fire hydrants as close as possible to street intersections, but
outside of the curb radius. This positioning of fire hydrants provides coverage along several streets.
When spacing requirements necessitate the installation of fire hydrants between street
intersections, they should be placed at the projection of lot lines between property owners. For
main replacement projects in established neighborhoods, fire hydrants should be designed as close
as possible to the old fire hydrant location, provided coverage is adequate. Neighborhood
residents are familiar with the fire hydrant being at that location and normally expect a replacement
fire hydrant to be placed at the same location. Fire hydrants are not to be installed closer than nine
(9) feet to any wastewater main, manhole, or appurtenance.
B. Fire hydrant spacing shall comply with the 2021 IFC Appendix C Fire Hydrant Locations and
Distribution, and be easily accessible by City staff and First Responders. See City of Denton Standard
Details W401A and 401B, and Standard Specifications 33 14 40 Fire Hydrants. Fire hydrants shall be
placed at a maximum of 500 feet apart in single-family residential areas and a maximum of 300 feet
apart in all other areas, unless a closer spacing is required by the IFC.
6.2.9 Meters and Meters Cans/Vaults
The City allows the following water meters, depending on the volume and nature of the customer flow
demands:
Table 6.2-F: Allowable Water Meters
Service
Size Meter Size Type AWWA Standard
1-in. ⅝-in. x ¾-in. Positive Displacement AWWA C700
1-in. ¾-in. x ¾-in. Positive Displacement AWWA C700
1-in. 1-in. Positive Displacement AWWA C700
2-in. 1½-in. Positive Displacement AWWA C700
2-in. 2-in. Positive Displacement AWWA C700
4-in. 3-in. Tru/Flo Compound See City Standard
Specification 33 14 18
4-in. 4-in. Tru/Flo Compound See City Standard
Specification 33 14 18
6-in. 6-in. Tru/Flo Compound See City Standard
Specification 33 14 18
6-in. 6-in. Protectus III Fire Service
(Shall be used for combination of domestic and fire service) Compound See City Standard
Specification 33 14 18
8-in. 8-in. Protectus III Fire Service
(Shall be used for combination of domestic and fire service) Compound See City Standard
Specification 33 14 18
Notes:
[1] Turbine meters shall be allowed for irrigation meters; not for domestic meters.
[2] Venturi meters shall be allowed when recommended by City Water Utilities based on Single-Family Equivalent calculations.
[3] Fire hydrant meters shall only be used for non-potable purposes.
[4] Vaults are required for all meters greater than two (2) inches.
[5] See Section 6.2.9.D for Furnishing and Installing meters.
[6] Non-standard sized water services are not allowed. Refer to the water service connection drawings on the City of Denton Standard
Details.
[7] Sites that require an irrigation meter shall have two (2) separate service line connections onto the main; one (1) for the domestic
meter, and the other for the irrigation meter.
Section 6: Water and Wastewater Design Criteria
6.2 Water Design Criteria
6.2.9 Meters and Meters Cans/Vaults
Design Criteria Manuals 140
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A. Number of Meters
One (1) meter is required for each residential, commercial, or industrial service connection, in
accordance with the Code of the City of Denton, Texas, Chapter 26, Article I, Sec. 26-9. An apartment
building, condominium, manufactured housing community, or mobile home park may be
considered a single commercial facility for the purpose of this section. The City’s standard policy is
that only one (1) meter for domestic use will be furnished to each lot. Exceptions to that policy are:
1. Multifamily, commercial, industrial, or institutional sites shall have a separate irrigation meter
from the domestic meter with a separate service line to the distribution main;
2. Multifamily developments with greater than 200 units shall be required to have two (2)
domestic meters for redundancy and reliability of water service, where each meter is located
on a different water main or separated by an inline valve. Note that Fire Code may require
redundant (secondary) fire suppression connections;
3. Multi-building sites where the configuration or size of the site makes a single meter location
impractical or infeasible;
4. Institutional Group I-2 Facilities as per IBC Sec. 308.3 and IPC Sec. 609; and
5. Submetering by the property owner to tenants of multifamily developments with a minimum
of five (5) units per building (or by condominium associations to member) shall be done at
the owner’s expense, with privately purchased and maintained meters, and in accordance
with the Public Utilities Commission 16 TAC Chapter 24 Subchapter I, as amended.
B. Sizing
In commercial and industrial projects, the design engineer shall consult with the owner or the MEP
engineer to identify proposed sizes and locations for domestic water meters, fire sprinkler
connections, and irrigation meters.
During Building Permit review, the City evaluates adequacy of meter size using Table E201.1,
“Minimum Size of Water Meters, Mains and Distribution Piping Based on Water Supply Fixture Unit
Values (w.s.f.u.)” of the version of the International Plumbing Code (IPC) as adopted by the City
(copy included herein as Table 6.2-G). The City’s Building Permit Plans Review uses the version of
the International Residential Code as adopted by the City, Table P2903.6, “Water-Supply Fixture-
Unit Values for Various Plumbing Fixture and Fixture Groups” (See Table 6.2-H) to estimate w.s.f.u.
To facilitate review of the proposed meter size, the design engineer shall submit a tabulation of
w.s.f.u.; a sample tabulation is provided herein in Table 6.2-J.
Contact the Water Utilities Department regarding criteria for sizing fire-rated master meters.
For commercial or industrial sites that utilize large amounts of water in their production process,
the developer shall provide estimated peak daily demand. Meter to be sized to 1.25 times (1.25x)
the peak daily demand.
The total service units for multifamily apartment projects with eight (8) or more units shall be
determined by multiplying the total number of bedrooms in the multifamily apartment project by
0.26 Single-Family Equivalents (SFEs).
Section 6: Water and Wastewater Design Criteria
6.2 Water Design Criteria
6.2.9 Meters and Meters Cans/Vaults
Design Criteria Manuals 141
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Table 6.2-G: Minimum Size of Water Meters, Mains, and Distribution Piping
based on water-supply fixture-unit (w.s.f.u) values
Meter and
Service Pipe
(inches)
Distribution
Pipe
(inches)
Maximum Development Length (feet)
PRESSURE RANGE 30 TO 39 PSI 250 300 400 500
3/4 1/21 2.5 2 1.5 1.5 1 1 0.5 0.5 0 0
3/4 3/4 9.5 7.5 6 5.5 4 3.5 3 2.5 2 1.5
3/4 1 32 25 20 16.5 11 9 7.8 6.5 5.5 4.5
1 1 32 32 27 21 13.5 10 8 7 5.5 5
3/4 1-1/4 32 32 32 32 30 24 20 17 13 10.5
1 1-1/4 80 80 70 61 45 34 27 22 16 12
1-1/2 1-1/4 80 80 80 75 54 40 31 25 17.5 13
1 1-1/2 87 87 87 87 84 73 64 56 45 36
1-1/2 1-1/2 151 151 151 151 117 92 79 69 54 43
2 1-1/2 151 151 151 151 128 99 83 72 56 45
1 2 87 87 87 87 87 87 87 87 87 86
1-1/2 2 275 275 275 275 258 223 196 174 144 122
2 2 365 365 365 365 318 266 229 201 160 134
2 2-1/2 533 533 533 533 533 495 448 409 353 311
PRESSURE RANGE 40 TO 49 PSI 40 60 80 100 150 200 250 300 400 500
3/4 1/21 3 2.5 2 1.5 1.5 1 1 0.5 0.5 0.5
3/4 3/4 9.5 9.5 8.5 7 5.5 4.5 3.5 3 2.5 2
3/4 1 32 32 32 26 18 13.5 10.5 9 7.5 6
1 1 32 32 32 32 21 15 11.5 9.5 7.5 6.5
3/4 1-1/4 32 32 32 32 32 32 32 27 21 16.5
1 1-1/4 80 80 80 80 65 52 42 35 26 20
1-1/2 1-1/4 80 80 80 80 75 59 48 39 28 21
1 1-1/2 87 87 87 87 87 87 87 78 65 55
1-1/2 1-1/2 151 151 151 151 151 130 109 93 75 63
2 1-1/2 151 151 151 151 151 139 115 98 77 64
1 2 87 87 87 87 87 87 87 87 87 87
1-1/2 2 275 275 275 275 275 275 264 238 198 169
2 2 365 365 365 365 365 349 304 270 220 185
2 2-1/2 533 533 533 533 533 533 533 528 456 403
PRESSURE RANGE 50 TO 60 PSI 40 60 80 100 150 200 250 300 400 500
3/4 1/21 3 3 2.5 2 1.5 1 1 1 0.5 0.5
3/4 3/4 9.5 9.5 9.5 8.5 6.5 5 4.5 4 3 2.5
3/4 1 32 32 32 32 25 18.5 14.5 12 9.5 8
1 1 32 32 32 32 30 22 16.5 13 10 8
3/4 1-1/4 32 32 32 32 32 32 32 32 29 24
1 1-1/4 80 80 80 80 80 68 57 48 35 28
1-1/2 1-1/4 80 80 80 80 80 75 63 53 39 29
1 1-1/2 87 87 87 87 87 87 87 87 82 70
1-1/2 1-1/2 151 151 151 151 151 151 139 120 94 79
2 1-1/2 151 151 151 151 151 151 146 126 97 81
1 2 87 87 87 87 87 87 87 87 87 87
Section 6: Water and Wastewater Design Criteria
6.2 Water Design Criteria
6.2.9 Meters and Meters Cans/Vaults
Design Criteria Manuals 142
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Table 6.2-G: Minimum Size of Water Meters, Mains, and Distribution Piping
based on water-supply fixture-unit (w.s.f.u) values
Meter and
Service Pipe
(inches)
Distribution
Pipe
(inches)
Maximum Development Length (feet)
1-1/2 2 275 275 275 247 213
2 2 365 365 365 365 365 365 365 329 272 232
2 2-1/2 533 533 533 533 533 533 533 533 533 486
PRESSURE RANGE OVER 60 PSI 40 60 80 100 150 200 250 300 400 500
3/4 1/21 3 3 3 2.5 2 1.5 1.5 1 1 0.5
3/4 3/4 9.5 9.5 9.5 9.5 7.5 6 5 4.5 3.5 3
3/4 1 32 32 32 32 32 24 19.5 15.5 11.5 9.5
1 1 32 32 32 32 32 28 28 17 12 9.5
3/4 1-1/4 32 32 32 32 32 32 32 32 32 30
1 1-1/4 80 80 80 80 80 80 69 60 46 36
1-1/2 1-1/4 80 80 80 80 80 80 76 65 50 38
1 1-1/2 87 87 87 87 87 87 87 87 87 84
1-1/2 1-1/2 151 151 151 151 151 151 151 144 114 94
2 1-1/2 151 151 151 151 151 151 151 151 118 97
1 2 87 87 87 87 87 87 87 87 87 87
1-1/2 2 275 275 275 275 275 275 275 275 275 252
2 2 365 368 368 368 368 368 368 368 318 273
2 2-1/2 533 533 533 533 533 533 533 533 533 533
Notes:
[1] Minimum size of building supply is ¾-in. pipe.
[2] User shall follow the most recently adopted code; above table was the most recent version at the time of publication of t his Manual.
Source: 2021 International Plumbing Code – Table E201.1
Section 6: Water and Wastewater Design Criteria
6.2 Water Design Criteria
6.2.9 Meters and Meters Cans/Vaults
Design Criteria Manuals 143
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Table 6.2-H: Water-supply fixture-unit (w.s.f.u) values for Various Plumbing
fixtures and Fixture Groups
Type of Fixtures or Group of Fixtures Load in w.s.f.u. values
HOT COLD COMBINED
Bathtub (with/without overhead shower head) 1.0 1.0 1.4
Clothes washer 1.0 1.0 1.4
Dishwasher 1.4 — 1.4
Full-bath group with bathtub (with/without shower head) or shower stall 1.5 2.7 3.6
Half-bath group (water closet and lavatory) 0.5 2.5 2.6
Hose bibb (sillcock)1 — 2.5 2.5
Kitchen group (dishwasher and sink with/without garbage grinder) 1.9 1.0 2.5
Kitchen sink 1.0 1.0 1.4
Laundry group (clothes washer standpipe and laundry tub) 1.8 1.8 2.5
Laundry tub 1.0 1.0 1.4
Lavatory 0.5 0.5 0.7
Shower stall 1.0 1.0 1.4
Water closet (tank type) — 2.2 2.2
Notes:
[1] The fixture unit value 2.5 assumes a flow demand of 2.5 GPM, such as for an individual lawn sprinkler device. If a hose bibb/sill cock
will be required to furnish a greater flow, the equivalent fixture-unit value may be obtained from this table or Table P2903.6(1).
[2] Supply loads in the building water-distribution system shall be determined by total load on the pipe being sized, in terms of w.s.f.u.,
as shown in Table P2903.6, and gallons per minute (GPM) flow rates [See Table P2903.6(1)]. For fixtures not listed, choose a w.s.f.u.
value of a fixture with similar flow characteristics.
[3] For SI units: 1 GPM = 3.785 Liters per minute (L/m).
[4] User shall follow the most recently adopted code. The above table was the most recent version at the time of publication of this
Manual.
Source: 2021 International Residential Code – Table P2903.6
Section 6: Water and Wastewater Design Criteria
6.2 Water Design Criteria
6.2.9 Meters and Meters Cans/Vaults
Design Criteria Manuals 144
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Table 6.2-I: Load Values assigned to Fixtures 1
Fixture Occupancy Type of Supply
Control Load in w.s.f.u values
COLD HOT COMBINED
Bathroom group Private Flush tank 2.7 1.5 3.6
Bathroom group Private Flushometer-valve 6.0 3.0 8.0
Bathtub Private Faucet 1.0 1.0 1.4
Bathtub Public Faucet 3.0 3.0 4.0
Bidet Private Faucet 1.5 1.5 2.0
Combination fixture Private Faucet 2.25 2.25 3.0
Dishwashing machine Private Automatic — 1.4 1.4
Drinking fountain Offices, etc. ⅜-in. valve 0.25 — 0.25
Kitchen sink Private Faucet 1.0 1.0 1.4
Kitchen sink Hotel, restaurant Faucet 3.0 3.0 4.0
Laundry trays (1 to 3) Private Faucet 1.0 1.0 1.4
Lavatory Private Faucet 0.5 0.5 0.7
Lavatory Public Faucet 1.5 1.5 2.0
Service sink Offices, etc. Faucet 2.25 2.25 3.0
Shower head Public Mixing valve 3.0 3.0 4.0
Shower head Private Mixing valve 1.0 1.0 1.4
Urinal Public 1-in. flushometer-valve 10.0 — 10.0
Urinal Public ¾-in. flushometer-valve 5.0 — 5.0
Urinal Public Flush tank 3.0 — 3.0
Washing machine (8-lb.) Private Automatic 1.0 1.0 1.4
Washing machine (8-lb.) Public Automatic 2.25 2.25 3.0
Washing machine (15-lb.) Public Automatic 3.0 3.0 4.0
Water closet Private Flushometer valve 6.0 — 6.0
Water closet Private Flush tank 2.2 — 2.2
Water closet Public Flushometer valve 10.0 — 10.0
Water closet Public Flush tank 5.0 — 5.0
Water closet Public or private Flushometer tank 2.0 — 2.0
Notes:
[1] For fixtures not listed, loads should be assumed by comparing the fixture to one listed using water in similar quantities and at similar
rates. The assigned loads for fixtures with both hot and cold water supplies are given for separate hot and cold water loads and for
total load. The separate hot and cold water loads are three-fourths of the total load for the fixture in each case.
[3] For SI units: 1 inch = 25.4 mm, 1 pound = 0.454 kg.
[4] User shall follow the most recently adopted code. The above table was the most recent version at the time of publication of this
Manual.
Source: 2021 International Plumbing Code – Table E103.3(2)
Section 6: Water and Wastewater Design Criteria
6.2 Water Design Criteria
6.2.9 Meters and Meters Cans/Vaults
Design Criteria Manuals 145
Published: January 2026 Go to Table of Contents
Table 6.2-J: Sample w.s.f.u Tabulation
Fixture Quantity
Load Values,
in Total w.s.f.u
(each)
Total
Fixture Units
Water Closet (Public; Flush Valve) 9 10.0 90
Water Closet (Public; Flush Tank) 3 5.0 15
Urinal (Public; ¾-in. Flush Valve) 5 5.0 25
Lavatory (Public) 10 2.0 20
Kitchen Sink (Hotel, Restaurant) 2 4.0 8
Service Sink 1 3.0 3
Shower Head (Private) 1 1.4 1.4
Total 162.4
Table 6.2-K: Land Use and Service Units/SFE Equivalencies
Meter Type Meter Size Typical Land Use
Single-Family
Equivalents
(SFEs)
Positive Displacement ⅝-in. x ¾-in. Residential – Single-Family
(Building less than 1,300 sq. ft. per lot size less than 6,000 sq. ft.) 0.5
Positive Displacement ⅝-in. x ¾-in. Residential – Single-Family 1.0
Positive Displacement ¾-in. x ¾-in. Residential / Commercial 1.5
Positive Displacement 1-in. Residential / Commercial 2.5
Positive Displacement 1½-in. Commercial 5.0
Positive Displacement 2-in. Commercial 8.0
Compound 3-in. Commercial / Industrial 22.5
Compound 4-in. Commercial / Industrial 50.0
Notes:
Source: City of Denton Approved Meter Manufacturer’s Specifications;
City of Denton Code of Ordinances Section 26-218 - Water and Wastewater Facilities - Exhibit F
C. Location
Water meters and meter cans and vaults shall be placed within a City ROW, Public Utility Easement
or Public Water Easement. Placement shall also satisfy the following requirements:
1. Located as close as possible to the public water main;
2. Easily accessible to City of Denton employees; and
3. Located in an unpaved area that does not conflict with vehicular or pedestrian traffic.
D. Furnishing and Installing
All meters two (2) inches and smaller, shall be furnished and installed by City Water Utilities for fees
per the current Fee Schedule. All meter assemblies three (3) inches and larger and their associated
vaults, shall be furnished and installed by Contractor at their expense and inspected by Public Works
Inspection and City Water Utilities.
E. Details
Details of the meter can assemblies for meter sizes two (2) inches and smaller are shown in the City
Section 6: Water and Wastewater Design Criteria
6.2 Water Design Criteria
6.2.10 Underground Utility Crossing
Design Criteria Manuals 146
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of Denton Standard Details.
Details of the meter vault assemblies for meter sizes three (3) inches and larger are shown in the
City of Denton Standard Details.
F. Backflow Prevention
Note that this section of the DCM, 6.2.9.F-Backflow Prevention will be superseded and void upon
the adoption of a formal City Ordinance governing backflow prevention assembly requirements.
Backflow Prevention Assemblies are required in accordance with the International Plumbing Code,
2021 IFC, 30 TAC § 290.44. Backflow Prevention Assemblies must be utilized as follows:
1. At each dedicated fire line connection. A flanged fire line valve shall be required to connect
to the tee located on the main line and a fire line valve shall be required outside the
downstream side of the vault or ROW line whichever applies;
2. After each meter of any site served by redundant domestic meters;
3. At facilities supporting Recreational Vehicle (RV) connections for the purpose of flushing
waste tanks;
4. At all services outside City limits, in accordance with 30 TAC § 290.47(f)); and
5. At all properties that have an auxiliary water source. These properties must protect
connections to the public water system using a reduced pressure backflow assembly (RPBA).
Backflow prevention devices shall be placed at the ROW or an easement line adjacent to the
connection to the public water system.
6.2.10 Underground Utility Crossing
Water mains shall be separated from wastewater mains as set forth in 30 TAC § 290.44(e) - Location of
Waterlines, as amended.
Where water mains are laid under or over another buried utility line or underground facility (i.e., storm drain,
culvert boxes, franchise utilities, etc.), special requirements may be necessary for the protection of the water
main. Table 6.2-L provides requirements for different crossing situations. This table is not a replacement for
separation requirements for sewer and water lines as governed by 30 TAC §§ 217.53 and 290.44, respectively.
Section 6: Water and Wastewater Design Criteria
6.2 Water Design Criteria
6.2.11 Fence or Wall Crossings
Design Criteria Manuals 147
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Table 6.2-L: Utility Crossing Requirements
Water Utility Crossing Utility Line Size (in.) Separation
(feet) Special Requirement
New/existing Water Under < 24 ≥ 2 None
New/existing Sewer Under < 24 ≥ 2 None
New/existing Water Under 24 to 42 ≥ 2 None
New/existing Sewer Under 24 to 42 ≥ 2 None
New Water Under > 42 ≥ 2 Encased in 150±psi pressure class pipe
Existing Water Under > 42 ≥ 2 Encased in split steel casing
New Sewer Under > 42 ≥ 2 Encased in 150±psi pressure class pipe
Existing Sewer Under > 42 ≥ 2 Encased in split steel casing
New Water Under ≥ 10 ≥ 2 Cased in steel pipe
Existing Water Under ≥ 10 ≥ 2 Cased in split steel pipe
New Sewer Under ≥ 10 ≥ 2 Cased in steel pipe
Existing Sewer Under ≥ 10 ≥ 2 Cased in split steel pipe
New/existing Water Over < 24 ≥ 2 None
New/existing Sewer Over < 24 ≥ 2 None
New/existing Water Over ≥ 24 ≥ 2 None
New/existing Sewer Over ≥ 24 ≥ 2 None
A. To minimize crossing impacts, crossings must be perpendicular, if possible.
B. Utility crossings with less than two (2) feet of separation require a design deviation request (which
will include special requirements) after providing a thorough analysis detailing physical and
economic factors involved.
C. Pursuant to the Code of the City of Denton, Texas, Chapter 25, Article II, Sec. 25-80-Facility Size and
Locations, all ROW user facilities are required to maintain a minimum separation of 24 inches from
all City utility system facilities. If a ROW user may encounter a hardship due to this requirement, the
ROW user may request a design deviation as detailed in Section 9 of this Manual.
D. Split-steel casing shall follow sizing requirements of pressure-rated casing.
E. See City Standard Specification Section 33 05 07 Steel Casing Pipe.
F. Casing spacers shall be placed not more than five (5) feet apart.
G. Encasement shall be extended a minimum of three (3) feet beyond the edge of the utility or facility
to be crossed. Water mains that cross utility lines in private easements must adhere to the
requirements of the easement owner, as well as those listed above.
6.2.11 Fence or Wall Crossings
A. Water mains should be routed to avoid entering private property. In circumstances where it is
impractical to avoid doing so, provisions are required to allow City staff to inspect, maintain , and
repair its infrastructure. Water mains crossing fences will require a design deviation request as per
Section 9 of this Manual, to be reviewed by the City’s Engineer, after thorough consideration of the
physical and economic factors involved. Design deviations may require additional provisions
beyond this Manual.
B. Water mains crossing under privacy fencing (wood, chain -link, or plastic) shall not require any
Section 6: Water and Wastewater Design Criteria
6.2 Water Design Criteria
6.2.15 Non-City Road Crossings
Design Criteria Manuals 148
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special protection.
C. Water mains crossing under other types of fencing will require the fence to be constructed of easily
removable panels or have gates that can be removed from the easement.
D. Water mains may not cross under retaining walls.
E. There must be at least two (2) feet of vertical separation between a water line and any utility or
storm drain crossing it.
6.2.12 Non-City Road Crossings
Crossings of State or County-controlled roads shall require the review and approval of the appropriate
regulatory agency after consultation with the City’s Engineer regarding crossing location. Crossings shall
meet the requirements provided by the controlling agency and by the City of Denton Standards. In the
event of different requirement levels for the same item, the more stringent standard shall apply. Crossing
locations must be easily and directly accessible on each side of such roads. Additional access easements
and installation of all-weather road surface may be required. The City of Denton shall have final say in the
location, criteria and standards of highway crossings considering access, maintenance and repairs.
6.2.13 Railroad Crossings
The design engineer shall, prior to the design of any railroad crossing, contact the appropriate railroad
company and regulatory agency to determine if there are any special requirements. Crossings shall be
discussed with and must be approved in writing by the City’s Engineer . In the event the City of Denton
Design Criteria are more stringent than those of the Railroad Company or regulatory agency, the City’s
standards shall apply. Crossing locations must be easily and directly accessible on each side of the railroad.
Additional access easements and installation of all-weather road surface may be required. The City of
Denton shall have final say in the location, criteria and standards of railroad crossings considering access,
maintenance and repairs.
6.2.14 Creek Crossings
Where a water main is laid under any flowing stream or semi-permanent body of water, such as a marsh or
pond, or an identified ESA (See DDC 7.4) the water main shall be installed in a separate watertight
encasement pipe, with valves on each side of the crossing to allow for the isolation and testing of that
portion of the water main to determine if there are any leaks , and to facilitate future repairs after
consultation with the City’s Engineer.
A primary consideration in the design of creek crossings is the prevention of soil erosion in the areas of
trench backfill. The design engineer shall determine the need and limits of any special embedment , and
determine and specify the limits for specialized backfills. Crossing locations must be easily and directly
accessible on each side of the creek. Additional access easements and installation of all-weather road
surface may be required. The City of Denton shall have final say in the location, criteria and standards of
creek crossings considering access, maintenance and repairs.
6.2.15 Elevated Crossings
Elevated crossings are not permitted for water mains except for special cases approved by the City’s
Engineer. Design requirements for approved elevated crossings shall be tailored to the specific project
characteristics.
Section 6: Water and Wastewater Design Criteria
6.2 Water Design Criteria
6.2.17 Tunneling, Boring, Jacking and Casing
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6.2.16 Tunneling, Boring, Jacking and Casing
Tunneling, boring, jacking and casing are methods used for water line placement under restrictive
conditions when open-cut construction is not allowed. Only straight pipe alignments for both horizontal
and vertical alignment are allowed.
Design engineers should consider the location, size, and depth of boring, tunnelling, and receiving pits
when choosing the beginning and ending stations for boring or tunnelling. A typical bore pit is between 35
and 40 feet in length to accommodate the boring machine and one (1) joint of pipe. Width of the bore pit
can vary depending on the depth and size of pipe, with the narrowest width being approximately 15 feet.
Tunnelling pits can vary greatly in size depending on the depth and size of the tunnel to be excavated.
Additional size and spacing requirements may be required as outlined in DDC 7.4 when working adjacent
to confirmed ESAs. The preferred location for the bore or tunnel pit is the lower elevation end of the bore
or tunnel; allowing any groundwater and/or boring slurry to drain from the tunnel into the bore or tunnel
pit. The water can then be removed by pumping.
A. Steel casing pipe, where required for open-cut or other than open-cut installation, shall conform to
City Standard Specification 33 05 07 Steel Casing Pipe, and be subject to the following guidelines:
1. Within Railroad ROW – the casing pipe size shall be sufficient to accommodate the outside
diameter (OD) of the carrier pipe bell of at least one City standard size greater than what is
required (See 6.2.4.B). Additionally, the casing pipe size must accommodate any external joint
restraint fittings required to restrain the carrier pipe. The annular space between the carrier
pipe and casing pipe shall not be grouted.
2. All other situations – the casing pipe size shall be sufficient to accommodate the OD of the
carrier pipe bell plus an additional four (4) inches of clear space. The carrier pipe shall be
restrained through grout applied to the annular space between the casing and carrier pipe
so external pipe restraints are not required.
B. Carrier pipes through casing shall be restrained as follows:
1. Segmented PVC and DIP shall be restrained with either external restraint fittings applied to
push-on bell and spigot pipe or by utilizing manufactured restrained joint pipe.
2. HDPE shall be restrained through fused joints.
3. Concrete steel cylinder pipe shall be restrained through welded joints.
All carrier pipes shall be supported with approved spacers and casing end seals. Refer to City of Denton
Standard Detail U208A and the current City approved Materials Submittal List.
Large diameter (48 inches or greater) or long length bores or tunnels (200 feet or greater) may require
tunnel liner plate instead of steel casing. These situations shall require design calculations to identify the
type and gage of tunnel liner plate to be utilized per Specification 33 05 08 Tunnel Liner Plate.
6.2.17 Existing Water Main Replacement
A. Whenever an existing main is to be replaced by a new main, use the following guidelines for
alignment and design:
1. The new line should be located as near as possible to the existing line; while allowing the
existing line to remain in service, until the new line is ready to be put into service.
2. If the existing line is in or next to a roadway, the new line should be placed under existing
pavement, not behind the curb in the parkway area.
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design Criteria
6.3.1 Requirements for Abandoning Water Mains
Design Criteria Manuals 150
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3. The new line should be designed to utilize the existing metering locations where possible.
B. The size of the new line should match the size of the existing line. If the existing line is a non -
standard size (i.e., 6-in. or 10-in.) then the new line should be sized for the next larger standard size.
The design engineer shall perform field investigations to determine pavement condition over the
existing main. The pavement may have been patched due to breaks in the existing main over the
years. Based on field investigations, the design engineer shall include additional quantities for
pavement replacement, if necessary.
6.2.18 Requirements for Abandoning Water Mains
The design engineer should note the limits and appropriate conditions for the abandoning of existing water
mains which are to be replaced by the construction of any proposed water mains.
The design engineer should also make allowances in the design to provide for the existing and proposed
mains to be in service simultaneously, until all customer services are transferred from the old main to the
new main with minimum interruption of service. If the construction of a proposed main necessitates the
abandoning of the existing main prior to the new main’s placement into service, th en provisions for a
temporary water main with services must be addressed by the design.
6.2.19 Water Treatment Plants, Ground Storage Tanks, ESTs, Pressure Tanks, and
Booster Pump Stations
If new public water treatment plants (WTPs), ground storage tanks (GSTs), ESTs, pressure tanks and/or
Booster Pump Stations are needed to support a development, the design shall be directed by the Water
Utility considering the needs of the development and the Water Utility System.
6.3 Wastewater Design Criteria
6.3.1 Estimated Wastewater Flows
For sewers in new developments, sewer lines and lift stations shall be designed to accommodate the
projected buildout flows from all residential, commercial, industrial, or institutional sources upstream of the
proposed sewer improvement. Figure: 30 TAC § 217.32(a)(3) Table B.1. - Design Organic Loadings and Flows
for a New Wastewater Treatment Facility (See excerpted information in Table 6.3-A) shall be used as a guide
to generate wastewater flows. However, minimum flow capacity for sizing of sewers for peak flow condition
shall not be less than the results of the following calculation procedures:
A. Delineate the wastewater drainage area that will drain into the sewer main or lift station. Include
all upstream offsite areas.
B. For the development site, use the following design parameters:
1. Table 6.3-A to generate the wastewater loading by type of use.
2. 3.2 capita per lot for single-family.
3. 2.5 capita per unit for multifamily.
4. Apply a 4.0 multiplier to the average daily flow to determine the peak flow.
C. For undeveloped upstream areas, use the following design parameters:
1. 4 lots per acre.
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design Criteria
6.3.1 Estimated Wastewater Flows
Design Criteria Manuals 151
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2. 3.2 capita per lot.
3. Average daily flow of 90 GPCD.
4. Apply a 4.0 multiplier to the average daily flow to determine the peak flow.
D. For developed residential upstream areas, use the following design parameters:
1. Count number of single-family lots.
2. Obtain number of multifamily units (available through DCAD)
3. 3.2 capita per lot for single-family.
4. 2.5 capita per unit for multifamily.
5. Average daily flow of 90 GPCD
6. Apply a 4.0 multiplier to the average daily flow to determine the peak flow
E. For developed non-residential upstream areas, use the following design parameters:
1. Average daily flow of 1,500 GPD per acre.
2. Apply a 4.0 multiplier to the average daily flow to determine the peak flow.
For replacement of existing sewers and construction of parallel sewers for additional capacity, wastewater
flow data may be provided by the City from data generated by City sewershed computer models. The cost
for modeling a project’s impact with the City’s collection system model will be the responsibility of the
developer and paid to the City.
Proposed impacts to the City’s system determined to, or likely to, cause (through hydraulic modeling or
other analysis) these limits to be exceeded, are prohibited without additional improvements to the public
system to address the capacity deficiency.
Table 6.3-A: Design Flows for a New Wastewater Treatment Facility
Source Remarks Daily Wastewater Flow
(Gal. per person)1
Municipality Residential 75 - 100
Subdivision Residential 75 - 100
Trailer Park 2 (Transient) 2½ Persons per Trailer 50 - 60
Mobile Home Park 2 3 Persons per Trailer 50 - 75
School Cafeteria & Showers
Cafeteria/ No Showers
20
15
Recreational Parks Overnight User
Day User
30
5
Office Building or Factory Facility must be designed for the largest shift 20
Hotel/Motel Per Bed 50 - 75
Restaurant Per Meal 7 - 10
Restaurant with bar or cocktail lounge Per Meal 9 - 12
Hospital Per Bed 200
Nursing Home Per Bed 75 - 100
Alternative Collection Systems, e.g., septic tanks Per Capita 75
Notes:
[1] City of Denton requires usage of the highest number of the TCEQ ranges.
[2] At the time of updating this Manual, the TCEQ is evaluating criteria for tiny homes, and should be consulted as appropriate.
Source: TCEQ Rules - 30 TAC §217.32(a)(3), Table B.1
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design Criteria
6.3.2 Size and Slope of Sewers
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6.3.2 Size and Slope of Sewers
After the design engineer has determined the wastewater flows per Section 6.3.1 of this Manual, the sewer
size can be determined using the following criteria. However, no sewer, other than service laterals and force
mains, shall be less than eight (8) inches in diameter.
The size and grade of the proposed sewer shall be evaluated using Manning’s formula
V= 1.49/n (R) 0.67 (S) 0.50 [Eqn. 6.1]
Where: V = velocity (in fps)
n = Manning’s coefficient of roughness; minimum 0.013
R = hydraulic radius (feet)
S = slope of energy grade line (feet per foot)
Proposed sewers shall be designed with slopes sufficient for velocity of three (3.0) fps, with a minimum
required velocity of two (2.0) fps. The minimum acceptable Manning’s “n” factor for design shall be 0.013,
which takes into consideration the slime, grit and grease layers that will affect hydraulics or hinder flow as
the pipe matures. The sewer pipe grades shown in Table 6.3-B are based on an “n” value of 0.013 and are
the minimum acceptable slope for sewer lines.
Table 6.3-B: Minimum and Maximum Pipe Slopes
Size of Pipe - ID
(inches)
Minimum Slope
(%)
Maximum Slope
(%)
Capacity Flowing Full at
Min. Slope (MGD)
8 0.335 8.40 0.45
10 0.25 6.23 0.71
12 0.20 4.88 1.03
15 0.15 3.62 1.62
18 0.115 2.83 2.25
21 0.095 2.30 3.07
24 0.08 1.93 4.14
7 0.07 1.65 4.91
30 0.06 1.43 6.23
33 0.055 1.26 7.66
36 0.045 1.12 9.17
The capacity of the sewer pipe flowing full shall be computed by the following equation:
C = 0.299/n (D) 2.67 (S) 0.50 [Eqn. 6.2]
Where: C = capacity (million gallons per day-MGD)
n = Manning’s coefficient of roughness; minimum 0.013
D = inside diameter (feet)
S = slope of the energy grade line (feet per foot)
Sewer mains shall be designed to convey peak flow at no more than 80% of full pipe capacity at system
buildout.
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design Criteria
6.3.4 Sewer Alignment
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A. High Velocity Protection
Where velocities greater than 10 fps will occur when a pipe flows full, based on Manning’s Equation
and an “n” value of 0.013, restrained joint pipe or external restraint systems must be utilized.
6.3.3 Sewer Alignment
Design engineers shall be guided by the following in the alignment of wastewater lines:
A. Collection system extensions must follow topographical depressions and extend to the upstream
drainage shed, considering storm drainage improvements. Crossing into other drainage sheds
require written approval from City’s Engineer;
B. For new construction in areas not served, sewer mains shall be laid straight between manholes. No
horizontal or vertical bends are allowed between manholes;
C. Avoid shifting mains from one side of the ROW to the other side of the ROW between street
intersections;
D. Where the bypass of existing flows is feasible, it is recommended that replacement mains be
constructed horizontally in the same trench;
E. Except for pipe crossings, no franchise utility shall be installed within five (5) feet of a sewer main;
and
F. Vertically parallel wastewater mains require written approval from the City’s Engineer. Details
regarding main access must be planned out including but not limited to the dedicated of easements
or City ROW to ensure ability to access the mains, calculation s and details showing distances from
the main that other utilities may not be placed to preserve ability to access .
6.3.4 Sewer Main Depth and Recommended Cover
A. Minimum depth for the design of sewer mains shall be determined by providing a 2% grade for the
lateral from the center of the house or building to the center of the proposed main and including
an additional two (2) feet drop. Therefore, for a house 100 feet from the proposed sewer main, the
designed depth of the main shall be at least four (4) feet below the FFE of the house since:
2 feet + (2% of 100 feet) = 4 feet [Eqn. 6.3]
The lateral also must have at least two (2) feet of cover at its shallowest point. The design engineer
is responsible for ensuring sufficient depth and grade is maintained to serve all building sites in the
sewer shed.
B. Recommended cover for all sewer mains is four (4) feet to six (6) feet. Minimum cover shall be
three (3) feet and six (6) inches or 3-½ feet. Any main approved via a Design Deviation to have less
than minimum cover shall be encased in Class “B” embedment per City Standard Specifications.
See Drawing U204 of the City of Denton Standard Details.
When establishing depth for proposed wastewater mains, design engineers shall consider the
impact of proposed water and drainage improvements especially on service laterals that cross those
improvements to connect to the wastewater main.
C. The maximum depth of sewer mains is 30 feet.
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design Criteria
6.3.7 Gravity and Force Main Sewer Pipe Material
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6.3.5 Gravity and Force Main Sewer Pipe Material
Gravity and Force Main sewer pipe shall meet the following criteria unless special circumstances require an
alternative and is approved by the City’s Engineer. Slope of grade across cover shall be a maximum of 4H:1V.
Table 6.3-C: Minimum and Maximum Pipe Slopes
Pipe Diameter Application Pipe Material
8-in. to 12-in. Gravity PVC – ASTM D3034, SDR 26; HDPE – ASTM D3350, DR-17
15-in. Gravity PVC – ASTM D3034, SDR 26
18-in. to 24-in. Gravity PVC – ASTM F 679, PS115; Fiberglass Reinforced Plastic – ASTM D3262
6-in. to 60-in. Force Main HDPE – ASTM D3350, DR-13.5;
DIP – AWWA C150/C151, CL52 or PC 350,
A. For gravity sewer pipe sizes over 24 inches in diameter, design calculations and pipe selection shall
be submitted by the development design engineer for review. Approvals will be provided on a
project specific basis.
B. Force main sewer pipe shall be designed to meet the working and surge pressure requirements of
the specific application. Design calculations and pipe selection shall be submitted by the
development design engineer for review.
C. Different pipe materials shall not be mixed between manholes. If it is anticipated that a mixing of
materials will occur, the design engineer shall design a manhole at the point of transition of pipe
materials. For previously placed stub-out of a material other than PVC pipe, design engineer shall
add a note to the plans calling for removal of the stub-out or change the material of the proposed
pipe for that section of pipe between manholes.
6.3.6 Sewer Pipe Embedment
The types of embedment and backfill for sewer mains are shown in Drawings U201, U202, U203A , and
U203C of the City of Denton Standard Details. Embedment requirements shall be based on sewer mains
under proposed pavement, unpaved areas and existing pavement.
6.3.7 Manholes
Manholes constructed on existing or proposed sewer lines shall be sized as follows:
Table 6.3-D: Manhole Sizing
Pipe Diameter Manhole Diameter
8-in. to 12-in. 4.0 feet (For depths greater than 12 feet, use 5.0 feet)
15-in. to 27-in. 5.0 feet
30-in. to 36-in. 6.0 feet
Notes:
[1] Special manholes shall be designed for mains larger than 36-in. diameter pipe.
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design Criteria
6.3.8 Sewer Laterals
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The types of manholes allowed by the City are shown in Drawings S101, S102, S103 , and S107B of the City
of Denton Standard Details. Additionally, connections to manholes must comply with City Standard
Specifications.
Generally, manholes shall be stationed on the main run, and where known, the stations of the side mains
should also be indicated. When connecting a proposed main to an existing main at a manhole, the
connection shall have the top inside elevation of the outfall main level with the top inside elevation of the
proposed main. Connections to brick manholes are prohibited.
At the discretion of Water Utilities, Field Operations, or Planning and Engineering Department staff,
manholes with known deficiencies will be required to be replaced.
Manholes deeper than 20 feet must be of monolithic construction, such as Glass-fiber Reinforced Polyester.
A. Manhole Locations
Manholes shall be provided at the following locations to facilitate maintenance, cleaning, and
inspection:
1. At the location of lateral connections that are 8-in. diameter or larger;
2. At 500 feet intervals on sewer mains 15-in. diameter or smaller; at 800 feet internals on mains
18-in. diameter through 30-in. diameter; at 1,000 feet intervals on mains 36-in. diameter
through 48-in. diameter; and at 2,000 feet intervals for 54-in. diameter and larger;
3. At all locations where pipe diameter or pipe material changes;
4. At all locations where the horizontal or vertical alignment of the sewer main changes;
5. At the ends of all mains with service connections. Two main upstream ends may not be
combined in one manhole;
6. At the end of any pipe segment at least 150 feet long;
7. At the end of every end-of-line (EOL);
8. Sewer service laterals are to be connected to the sewer main line and not into a manhole
unless it is a size-on-size connection;
9. Manholes shall not be placed in sidewalks, pedestrian ramps, driveway approaches, or in the
bottom or on the slopes of a drainage channel or drainage structure;
10. At a minimum of 40 feet from any railroad track; and
11. Separation of utilities around manholes shall be a minimum distance of five (5) feet , to allow
for maintenance and repair.
6.3.8 Sewer Laterals
A. Water Utilities, Field Operations, or Engineering and Planning staff reserve the right to permit utility-
supervised connections to the collection system by non-City staff. Note that the developer will be
responsible for all surface rehabilitation associated with connecting to the City’s Water Utilities.
Surface rehabilitation must match existing site conditions or better.
B. Laterals may not serve more than one (1) lot.
C. Minimum lateral sizes from the sewer main to the public cleanout are as follows:
1. For single-family: four (4) inches
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design Criteria
6.3.12 Underground Utility Crossings
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2. For residential duplex, triplex, and quadplex: six (6) inches
3. For local retail, light commercial, apartment, manufacturing and industrial: six (6) inches
D. Single-way clean-outs shall be provided on laterals at the public easement or ROW line. Double-
way cleanouts are not allowed. See Drawings S403 and S404 of the City of Denton Standard Details.
E. Manholes shall be provided for lateral connections when the lateral pipe diameter is equal to the
main sewer pipe diameter or if the lateral is eight (8) inches in diameter or larger.
F. Laterals shall be constructed to the property line and shall be located at a point five (5) feet
downstream from the center of the lot on unimproved property. For improved property, design
engineers should use technical judgement in lateral placement.
G. Preferred grade for lateral construction within the ROW/PUE is 2%. Laterals within ROW/PUE shall
not be designed with less than 1% grade.
6.3.9 Underground Utility Crossings
Wastewater mains and manholes shall be separated from water mains as set forth in 30 TAC §217.53 (d) -
Separation Distances and 30 TAC §290.44 - Water Distribution.
The requirements of Section 6.2.10 of this Manual shall govern the crossing of underground utility lines by
wastewater mains.
6.3.10 Fence or Wall Crossings
The requirements of Section 6.2.11 of this Manual shall govern the crossing of fences or walls by wastewater
mains.
6.3.11 Non-City Road Crossings
Crossings of State or County-controlled roads shall require the review and approval of the appropriate
regulatory agency after consultation with the City’s Engineer regarding crossing location. Crossings shall
meet the requirements provided by the controlling agency and by the City of Denton Standards. In the
event of different requirement levels for the same item, the more stringent standard shall apply. Crossing
locations must be easily and directly accessible on each side of such roads. Additional access easements
and installation of all-weather road surface may be required. The City of Denton shall have final say in the
location, criteria and standards of highway crossings considering access, maintenance and repairs.
6.3.12 Railroad Crossings
The design engineer shall, prior to the design of any railroad crossing, contact the appropriate railroad
company and regulatory agency to determine if there are any special requirements. Crossings shall be
discussed with must be approved in writing by the City’s Engineer. In the event the City of Denton Design
Criteria are more stringent than those of the Railroad Company or regulatory agency, the City’s standards
shall apply. Crossing locations must be easily and directly accessible on each side of the railroad. Additional
access easements and installation of all-weather road surface may be required. The City of Denton shall
have final say in the location, criteria, and standards of railroad crossings considering access, maintenance,
and repairs.
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design Criteria
6.3.15 Creek Crossings
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6.3.13 Creek Crossings
When a sewer main crosses a creek or channel, the design engineer must evaluate the condition of the
creek bed and ensure erosion control is provided. Backfill material and minimum construction criteria are
shown in the City of Denton Standard Details S701 and S702. These criteria include creek bed soil and
condition, as well as presence of exposed rock. When working in these areas, minimize storage of soil,
materials, and equipment near floodways and waterways. Crossing locations must be easily and directly
accessible on each side of the creek. Additional access easements and installation of all-weather road
surface may be required. The City of Denton shall have final say in the location, criteria, and standards of
creek crossings considering access, maintenance and repairs.
A. Siphons
For creek or channel crossings where a Low-Water Channel Crossing is not feasible, design of an
inverted siphon crossing is permissible when approved by the City’s Engineer through a design
deviation request. Inverted siphons shall not have less than two (2) barrels, with a minimum pipe
size of eight (8) inches, and shall be provided with necessary appurtenances for convenient flushing
and maintenance. Access structures are required at each end of the siphon, with adequate
clearance for maintenance and cleaning purposes. Bank and channel stabilization may be required
to protect the crossing lines and casing of the carrier pipe may be required to meet environmental
or other restrictions. Siphon locations must be easily accessible on each side of the creek by heavy
equipment for maintenance. Additional access easements and installation of all-weather road
surface may be required. The City of Denton shall have final say in the location, criteria, and
standards of creek crossings considering access, maintenance, and repairs.
6.3.14 Tunneling, Borings, Jacking, and Casing
Force main tunnels and bores shall follow the same requirements as are laid out for water mains in Section
6.2.16 of this Manual.
6.3.15 Abandonment of Sewer Mains
A. The design engineer should note the limits and appropriate conditions for the abandoning of
existing wastewater mains which are to be replaced by the construction of any proposed
wastewater mains.
B. The design engineer should also make allowances in the design to provide for the existing and
proposed mains to be in service simultaneously until all customer services are transferred from the
old main to the new main with minimum interruption of service. If the construction of a proposed
main necessitates the abandoning of the existing main prior to the new main’s placement into
service, then provisions for a temporary wastewater main with services must be addressed by the
design.
C. Typically, abandoned lines may be left in place with only the ends being plugged with grout or
concrete. However, the City may require special abandonment actions including, but not limited to,
filling the abandoned wastewater main with grout, removal and proper disposal of all above ground
appurtenances, and removal and proper disposal of the abandoned pipe. In situations where a
manhole is being left in service even though one (1) or more lines into the manhole are being
abandoned, the abandoned line shall be cut and plugged outside of the manhole. However, if the
City determines that the pavement is in good condition the City may allow the abandoned line to
be plugged from inside of the manhole.
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design Criteria
6.3.17 Abandonment of Manholes
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6.3.16 Abandonment of Manholes
If a manhole as well as the sewer main is to be abandoned, the method described in Abandonment of
Sewer Mains, above, along with the minimum guidelines shown in Drawing S105 of the City Standard
Details, shall be used.
6.3.17 Lift Stations
The need to construct a lift station should be determined only after a thorough analysis of the physical and
economic factors involved. A Preliminary Engineering Report is required, which lists all factors and adheres
to current state regulations. The City reserves the right to review each proposal and determine whether
there is enough merit to justify a lift station. Any lift station located in the City of Denton CCN must adhere
to these requirements.
A. Preliminary Design Submittal
A preliminary design submittal is required for each lift station proposed. The submittal shall include
a written report and a map prepared by a PE licensed by the State of Texas.
1. The plans submitted shall contain the following information, at a minimum:
a. Be to scale, with the scale indicated;
b. A north arrow;
c. A location map;
d. Delineation of the boundary of the proposed development;
e. Delineation of the boundary of the sewershed in which the development lies ;
f. The area in acres of the development;
g. The area in acres of the sewershed contributing to the lift station;
h. The proposed land use or uses for the development;
i. The proposed land use or uses for the sewer basin;
j. The proposed lift station site, along with the GPS coordinates;
k. The proposed force main routing and size;
l. Delineation of the 100-year flood plain and ESAs;
m. Location and size of the existing collection system at the tie-in point;
n. Contour lines (2-ft. intervals);
o. Show how storm drainage is taken off site; and
p. Property lines.
2. The written report shall include the following information:
a. A general narrative about the proposed development and the circumstances that
warrant a lift station, including a phasing plan detailing the utilization and station
limitations from initial flow to buildout;
b. Influent hydraulic calculations showing:
i. Area in acres of the sewer basin and the development;
ii. The area of each proposed land use for the development and for the projected
land use(s) for the basin;
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design Criteria
6.3.17 Lift Stations
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iii. The design flow for the basin and the development;
iv. The peak flow for the basin and the development;
v. Elevation of the proposed lift station site; and
vi. The elevation of the proposed discharge point of the force main.
c. Preliminary wet well volume calculations;
d. Preliminary force main size;
e. Cost estimates for proposed lift station(s) and force main(s), and cost estimates for a
gravity line in lieu of the lift station if possible;
f. Ground water levels included in a comprehensive geotechnical report for the proposed
site areas; and
g. A copy of the summary transmittal letter to TCEQ showing agency approval of proposed
plans.
B. Site Layout
1. Station Siting:
The following are the minimum criteria for station sites:
a. The station shall be protected from the 100-year flood and shall be accessible during a
100-year flood;
b. The station should be located as remotely as possible from populated areas. The entire
station site shall be completely enclosed with an 8-ft. high, opaque concrete or masonry
wall, with an opaque sliding gate with a minimum width of 16 feet on track flush with
the ground. All shall be of an architectural style and colors blending with the
development architecture, as approved by the city;
c. The lift station site shall be large enough to allow the construction of the lift station to
serve the upstream basin(s), and its replacement while maintaining active service
without a bypass;
d. The station site must have verified radio communication ability with the City’s central
Supervisory Control and Data Acquisition (SCADA) antenna location;
e. The station shall have a minimum 16-ft. wide drive approach and be accessible by City
of Denton service trucks, without requiring vehicles to turn after entering the drive
approach to the station;
f. The station will include an approved odor-control system;
g. The station site and its access shall be dedicated as a separate lot to the City, as City
property;
h. The station site cannot be located within the boundaries of any private entity intended
to regulate property including, but not limited to, HOAs, COAs, and POAs;
i. The station site shall be located so it may serve as much as the entire sewer basin as
possible. This may require the station to be located off -site of the development. When
it is required that the station serve a larger area than the proposed development, the
developer may enter into a pro-rata contract with the City to be reimbursed the cost of
excess capacity as other developments tie to the system; and
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design Criteria
6.3.17 Lift Stations
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j. The on-site generator must have an unobstructed 36 -in. buffer on all sides and be
accessible by City service vehicles.
2. Wet Well/ Dry Well Arrangement
a. Orientation shall consider the routing of incoming sewers and force main;
b. Orientation shall allow at least a 2-ton vehicle to directly access the wet well or the dry
well, forwards and backwards or larger vehicle as appropriate;
c. Wet wells and dry wells shall be separate structures;
d. Wet wells shall have sloped bottoms to avoid excess sludge deposits;
e. The wet well shall have a lockable aluminum door with an aluminum frame and safety
grating. The minimum opening size shall be 4-ft. x 6-ft. with two (2) doors large enough
to adequately maintain the wet well. Door and frame shall be Bilco Type K, KD or an
approved equal;
f. The dry well or valve vault shall have a lockable aluminum door with an aluminum frame
and safety grating. The minimum opening size shall be 2-ft. x 3-ft. or large enough to
adequately maintain the dry well or meter vault. Door and frame shall be Bilco Type K,
KD or an approved equal;
g. The wet wells, dry wells, manholes, valve vaults and meter vaults, including decks, shall
all be cast-in-place concrete only. No other materials are acceptable. See City Standard
Specification 33 05 64 Concrete Wet wells, Valve Vaults, and Appurtenances for Lift
Stations;
h. The coating for the wet well exterior and interior walls shall be coated as specified in
Specification 33 05 64 Concrete Wet wells, Valve Vaults, and Appurtenances for Lift
Stations;
i. The wet well shall be hydrostatically tested to the top of the wet well for 48 hours prior
to placing the lift station into service. Only losses due to evaporation will be acceptable;
and
j. Provisions shall be made to remove water from the dry well, valve vault or without
allowing gas or water from the wet well into these structures.
3. Site Access
a. Access will be provided by concrete entrance and pad for aesthetics and ease of
maintenance;
b. Access shall be functional during a 100-year flood. The road surface shall be above the
water level caused by a 100-year return period storm;
c. Every station more than 100 feet from a public street requires a turn -around adjacent
to the lift station, sized large enough to accommodate a City service truck with
generator;
d. The equipment rack shall not obstruct vehicle access to the wet well or the dry well; the
location must be approved during the review process. It shall be placed at an easily
accessible elevation and include a canopy; and
e. Site inside the fence shall be an all-weather surface, such as ¾-in. crushed rock or flex-
base.
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design Criteria
6.3.17 Lift Stations
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4. Passive Ventilation
a. Passive ventilation shall be screened to prevent insect access to the wet well or any
vaults where ventilation is required. Minimum diameter of air vents shall be four (4)
inches. Vent outlet shall be at least one (1) foot above the 100-year flood elevation. The
passive ventilation system must be sized to vent at a rate equal to the maximum
pumping rate of a lift station, but not to exceed 600 fpm through a vent pipe.
C. Hydraulic Design
For influent flow, the preliminary design report shall include the design flow and the peak flow for
the development and the sewer basin. The design flow shall be calculated in accordance with TCEQ
rules. Refer to Section 6.3.1 - Estimated Wastewater Flows herein for peak flow calculations.
1. Pump Capacity
a. Firm pumping capacity is the pumping capacity of the station with the largest pump out
of service.
b. The firm pumping capacity shall be greater than the peak flow for the entire sewer basin.
If the sewer basin is significantly larger than the proposed development and it is not
feasible to design for this flow, the firm pumping capacity may be designed to handle
a portion of the basin with approval from the City’s Engineer.
c. The pump curves shall be selected so the pumps will run near the best efficiency point
during normal operating conditions. The selected curves shall also be such that the
pumps do not approach shut-off head when they are running simultaneously.
d. System head curves, pump curves and head calculations shall be submitted.
Calculations and pump curves at both minimum (all pumps off) and maximum (last
normal operating pump on) static heads, for a C value of both 100 and 140, must be
provided for each pump and for the combination of pumps with modified pump curves.
2. Wet Well Volume
a. Wet well volume for a submersible pump station is the volume contained above the top
of the motor, or as specified by the pump manufacturer, to the bottom of the influent
pipe. TCEQ Rule §217.60(b)(4) (d) A gravity pipe discharging to a wet well must be
located so that the invert elevation is above the liquid level of a pump's "ON" setting.
b. Wet well volume for all other non-submersible pump stations is the volume contained
in an area from a minimum of two (2) feet above or distance at which vortexing does
not occur above the top of the intake of the pump.
c. High level alarm elevation shall be a minimum of 48 inches below the top of the wet
well or 48 inches below the flow line elevation of the lowest influent pipe, whichever
elevation is lower. Wet well volume shall be calculated by the following method:
T = V/(D – Q) + V/Q [Eqn. 6.4]
Where: T = Total time between successive pump starts in minutes (operating cycle)
D = Rated pump capacity (in GPM)
V = Storage volume between lead pump on and pump off elevations (in
gallons)
Q = Inflow to wet well (in GPM)
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design Criteria
6.3.17 Lift Stations
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Note: The operation cycle ‘T’ shall not be less than 10 minutes for Average Flow and not
more than 60 minutes for Minimum Flow conditions.
d. Per TCEQ Rules, 30 TAC § 217.63:
i. Systems for preventing the discharge of wastewater must operate for a duration at
least equal to the longest power outage on record for the past 60 months, or at
least 20 minutes, whichever is longer. The design must be based on peak flows,
inflow, and infiltration. If the longest power outage on record for the past 60
consecutive months is greater than 48 hours and generators will be used to provide
backup power, then the owner must have a contract in place that guarantees fuel
supply during an emergency. The owner must also have sufficient storage capacity
at the wastewater treatment facility for the fuel required for the duration of the
emergency.
ii. For calculation purposes, the owner must assume that the lift station wet well is
full to the pump activation level when the power outage period begins.
3. Force Main Capacity
a. Force main capacity shall be sized to meet the capacity of the entire sewer basin. The
force main may be designed to handle a portion of the basin with approval from the
City’s Engineer.
b. The minimum force main size shall be four (4) inches in diameter, except for Grinder
Pump lift stations.
c. The minimum recommended velocity is three (3) fps, and the velocity shall not be less
than two (2) fps when only the smallest pump is in operation.
d. The maximum velocity through a force main shall not be more than six (6) fps and will
require confirmation per 30 TAC §217.67 that the pipeline will not fail.
D. Pumps
Pump specifications are listed in the City of Denton Specification 33 25 02 Sewage Pumps.
Substitutions or deviations from the list of acceptable pumps require the approval of the City’s
Engineer. The number of pumps must comply with 30 TAC § 217.61(e). If pumps are to have a
variable capacity, Variable Frequency Drives (VFDs) are to be specified. Stations requiring three
pumps must be equipped with VFDs on at least two of the pumps.
E. Mechanical
1. Force Mains
a. Force mains shall be laid to City of Denton Standard Specifications.
b. Plans shall include plan and profile for the force main, including valves every 2 ,000 feet
per 30 TAC § 217.67.
i. Valves must be resilient wedge gate valves and conform to the Section 33 14 20
Resilient Seated (Wedge) Gate Valves of the City of Denton Standard
Specifications;
ii. Valves must be in a manhole and conform to Section 6.3.10 of this criteria manual
and Section 33 05 61 Cast-In-Place Concrete Manholes of the City Standard
Specifications; and
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design Criteria
6.3.17 Lift Stations
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iii. The force main shall have an isolation valve immediately downstream of the flow
meter vault.
2. Lift Station Interior Piping
a. Piping inside the lift station shall be ductile iron meeting AWWA C-150 and C-151. All
fittings shall be ductile iron meeting AWWA C-110 or C-150. Interior of the pipe and
fittings shall be lined with American Polybond Plus, which consists of a primer layer of
5 mils thick fusion bonded epoxy and 55 mils thick of modified DuPont Fusabond
Polyethylene, or approved equal.
b. All nut and bolt assemblies potentially exposed to sewer gases shall be ASTM 316
stainless steel.
3. Isolation Valves
a. Each pump shall have one (1) isolation valve downstream of the pump, in a separate
vault.
b. Isolation valves shall be resilient seat gate valves or plug valves meeting the City of
Denton Standard Construction Specifications.
4. Check Valves
a. Check valves shall be controlled closing swing check valves with a lever arm or a ball
check. There must be at least 15 feet of vertical head downstream in order to use a ball
check valve.
b. A check valve shall be located upstream of the isolation valve in a separate vault.
c. All nuts and bolts shall be stainless steel.
5. Air Release / Vacuum Valves
a. Air release valves of a type suitable for wastewater service shall be installed along the
force main where the force main would be prone to trapped air.
b. The type of valve shall be a combination of air release and vacuum breaker (See Drawing
S803 on Sheet 6 of the City Standard Details). The design engineer shall determine the
type and location, subject to approval of the City’s Engineer.
c. Calculations for valve type and valve sizing shall be provided to the City.
d. Locations of the air release/vacuum valves shall be shown on the plan and profile sheets
for the force main.
e. Air release valves along the force main outside of the lift station site must be located in
a vault as shown in Standard Details.
f. Air release valves within the lift station valve vault shall have air vents plumbed to the
vault drain.
6. Generators
a. On-site generators shall be installed to serve as the source of back-up power for lift
stations. They must be sized for 125% of the largest pump motor, plus 100% of the
additional pump motors and other loads.
b. Generators shall be mounted on a concrete foundation designed to handle the weight
of the generator.
c. Generators shall use diesel for fuel unless explicit written permission is granted to use a
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design Criteria
6.3.20 Low-Pressure or Alternative Collection Systems
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different fuel.
d. Electrical receptacles for a mobile load bank shall be provided in the electrical design.
e. Generators rated for 500KW or more shall be provided with a permanent load bank
situated to adequate dissipate the heat generated on the lift station site.
f. Generators shall be furnished with sound attenuation appropriate for the location.
7. Hoists
Station designs that exceed or are likely to exceed the lifting capabilities of the existing City
Water Reclamation service trucks are to provide permanent onsite hoists rated for the lifting
of the heaviest assembly in the wet well, considering rag accumulation.
F. Electrical, Instrumentation, and Supervisory Control and Data Acquisition (SCADA)
Requirements
1. In accordance with the Lift Station Instrumentation and Control Panel Build Agreement, the
contractor building the lift station is required to utilize a pre-approved vendor from the City's
current list to perform the specified Instrumentation and Controls (I&C) and SCADA work.
The selection of the vendor for a specific project will be made during the pre-construction
phase and will be based on vendor availability and project requirements.
2. Provide a radio pathway study showing line of sight from the lift station to the receiver at
Pecan Creek Water Reclamation Plant.
3. Sites equipped with Variable Frequency Drives (VFDs) shall provide a climate-controlled
building for housing all electrical and electronic equipment.
4. Adequate lighting of the lift station wet well, valve vault, pump control equipment, electrical
and instrumentation equipment shall be included with the station design. All lighting
provided should be LED lighting.
6.3.18 Low-Pressure or Alternative Collection Systems
Low pressure collection systems may be allowed with specific approval by the City’s Engineer.
6.3.19 Wastewater Treatment Plants, And Peak Flow Detention Facilities
If wastewater treatment plants or peak flow detention facilities are needed to support a development, the
design shall be directed by the Water Utility considering the needs of the development and the Wastewater
Utility System.
6.3.20 On-Site Sewage Facilities
A. General
Planning, design and operation of on-site sewage facilities within the City of Denton must comply
with the current 30 TAC Ch. 285 for On-Site Sewage Facilities, as amended. The property owner
proposing to use an on-site sewage facility shall comply with the criteria listed in this Section, and
Section 7.6.16 of the City of Denton DDC, as amended.
B. Permits Required
Any owner of a residential, commercial, or institutional building who utilizes an on-site sewage
facility is required to secure a permit from the City of Denton to construct, alter, repair, or extend
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design Criteria
6.3.21 Pretreatment Device: Grease Interceptors / Grit Traps / Oil Separators
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an on-site sewage facility regardless of the size of the lot or tract of land. Contact the Environmental
Services Department at the Pecan Creek Water Reclamation Plant for details on permit fees and
maintenance requirements.
C. Site Evaluations
A PE or a professional sanitarian, licensed by the State of Texas, must perform site evaluations.
D. Planning Requirements
A PE or a professional sanitarian, licensed by the State of Texas, must prepare on-site sewage facility
plans.
E. On-Site Sewage Facility Land Use Requirements
Lots or tracts of land where an on-site sewage facility is proposed must have the following minimum
area size.
1. A minimum of one (1) acre when a public water system serves the tract or lot; and
2. A minimum of two (2) acres when a private water well is located on the tract or lot.
6.3.21 Pretreatment Device: Grease Interceptors / Grit Traps / Oil Separators
A. General
Planning, design, and operation of pretreatment devices within the City of Denton must comply
with the most current City of Denton Plumbing Code, Chapter 28; Article VII; Section 28-56, as
amended. The property owner proposing to use and operate a grease trap shall comply with the
criteria listed in this Section and abide by required responsibilities outlined in City of Denton Code
of Ordinances Chapter 26; Article XII – Liquid Waste.
Definitions can be found in the City of Denton Code of Ordinance, Chapter 26, Article XII, Section
26-306 and Chapter 26, Article V, Section 26-154.
B. Applicability
Any user of the publicly owned treatment works (POTW), as defined by Section 26-154, and meeting
the definition of “generator,” as defined by Section 26-306, shall be required to install a
pretreatment device in accordance with locally adopted plumbing codes as amended. Food service
establishments shall not share grease interceptors unless specifically authorized by the City’s
Engineer.
These requirements are applicable to all commercial food service establishments, including those
undergoing:
1. New construction
2. Interior remodeling to accommodate expansion or operational modifications
3. Changes of ownership/occupancy
4. Failures to meet limitations outlined in article V, Chapter 26 of the Code of the City of Denton,
Texas
5. Discharges which may cause blockages in the wastewater collection system
C. Review Required
Plumbing plans for new facilities must be prepared by a plumber or a PE, licensed by the State of
Texas, and submitted as a part of the development process. These plans must show the fixtures
draining into the pretreatment device. Plans must also include the flow-through rating of the
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design Criteria
6.3.21 Pretreatment Device: Grease Interceptors / Grit Traps / Oil Separators
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pretreatment device as well as the grease or solids retention capacity and, the location of the down-
stream sampling port. Plumbing plans for existing facilities must be submitted when applying for a
certificate of occupancy. These plans must show the fixtures draining into the pretreatment device
and indicate the flow through rating and grease and solids capacity of the pretreatment device.
D. Construction/Installation
All permitting, construction, and inspection activities must be completed in accordance with the
City of Denton Plumbing Code Chapter 28. Additionally, the following specifications must be
incorporated into pretreatment device design.
1. Each manhole access shall have minimum 20-in. diameter clear opening.
2. Pretreatment devices are to be installed at a minimum distance of 10 feet from sinks and
dishwashers to allow for adequate cooling of the wastewater. Water temperatures must be
less than 120 degrees prior to entering the pretreatment device.
3. Pretreatment devices shall be constructed of a material that is compatible with the type of
waste generated by the Facility and treated by the device.
4. All grease bearing waste streams should be routed through an appropriate grease
trap/interceptor, including: three-compartment sinks, pot/pan sinks, soup kettles, hand-
washing sinks, automatic dishwashers, mop sinks and floor drains.
5. Any pretreatment device must have a sample port allowing for the instantaneous grab
sampling of the effluent of the device. The sample port must be solely representative of the
process wastewater and sanitary tie-ins must be done down-stream of the sampling port.
The proposed sampling port must allow for a wide-mouthed 250-mL amber glass bottle to
be submerged or partially submerged into the effluent. Interior, above-ground
hydromechanical grease interceptors with a liquid capacity of 100 gallons or less may install
a sample spigot with a ball valve in leu of a sample port due to space constraints with City
approval. The sample spigot must be solely representative of the process wastewater and
sanitary tie-ins must be done down-stream of the sample spigot. Sample wells will have a
minimum 12-in. diameter access cover. Mechanical Traps and Interceptors that are installed
above ground must be equipped with an influent flow regulator and an effluent valve
assembly that allows for sample collection.
Unless otherwise approved in writing by the City’s Engineer, all fixtures, equipment, and drain lines
located in the food preparation, alcohol service, clean-up, and food service areas of a food service
establishment shall be connected to a grease interceptor. Fixtures required to connect to a grease
Interceptor shall include but are not limited to pot sinks, pre‐rinse sinks, hand sinks, prep sinks,
dishwashers, soup kettles, braising pans, wok ranges, mop sinks, floor sinks, floor drains, and
wastewater generated from exhaust fan hood cleaning operations.
E. Grease Interceptor Sizing Requirements
Sizing methods described herein are intended as guidance in determining grease trap/interceptor
sizes that will afford the City’s sanitary sewer system a minimum degree of protection against grease
and other obstructing materials. Sizing determinations are based on operational data provided by
business owners or their contractors. In approving a customer’s plumbing or grease interceptor
design, the City does not accept liability for the failure of a system to adequately treat wastewater
to achieve effluent quality requirements specified under City of Denton Code of Ordinance Chapter
26. It is the responsibility of the wastewater generator and/or contractors to insure the appropriate
level of treatment necessary for compliance with environmental and wastewater regulations.
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design Criteria
6.3.21 Pretreatment Device: Grease Interceptors / Grit Traps / Oil Separators
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1. Gravity Grease Interceptors (GGI) shall meet the requirements of ASME A112.14.6 and
IAPMO/ANSI Z1001. The required capacity of gravity grease interceptors shall be determined
by multiplying the peak drain flow into the interceptor in GPM by a retention time of 30
minutes as required by the International Plumbing Code.
2. Hydromechanical Grease Interceptors (HGI) shall be designed and tested in accordance with
ASME A112.14.3 and/or CSA B481.1. Sizing shall be in accordance with HGI Sizing and
Selection, as shown in the following two-step process:
a. Step 1: Size by Flow Rate
The minimum flow rate for HGIs may be calculated by either using pipe diameter or
fixture volume using either a one-minute or two-minute drainage period. Use a one-
minute drainage period when the interceptor will be installed inside of the building and
has indirectly connected fixtures. When the interceptor will be installed outside of the
building, use a two-minute drainage period.
i. Fixture Volume Sizing
Use the following formula for sizing fixtures by volume with a 75% fill factor:
Fixture Capacity Gallons = [ (L x W x H ) / 231 ] x 0.75 [Eqn. 6.5]
Note that,
Fixture Capacity Gallons x 1 = one-minute drainage period (GPM)
Fixture Capacity Gallons x 0.5 = two-minute drainage period (GPM)
Example calculations are shown below for a three-compartment sink with each
compartment dimensions being 18 x 24 x 12 inches:
18 x 24 x 12 = 5184 cu. in.
5184 / 231 = 22.44 fixture capacity gallons
22.44 x 3 = 67.3 total fixture capacity gallons (three bowls)
67.3 x 0.75 = 50.4 total fixture capacity after loading factor (75%)
50.4 x 1 = 50 GPM one-minute drainage period
50.4 x 0.5 = 25 GPM two-minute drainage period
To determine the minimum required flow rate for the HGI, calculate the capacity
of each fixture that will be connected and add the volumes together and use the
appropriate drainage period. An appropriate HGI must be certified to meet the
minimum flow rate as calculated.
b. Step 2: Calculate Grease Capacity
Once the minimum flow rate has been established as detailed in Step 1, the minimum
grease storage capacity for the HGI required for the desired pump-out frequency is
calculated as follows:
Grease Capacity Needed = Meals per day x GPV x DPC [Eqn. 6.6]
Where: GPV = Grease Production Values (See Table 6.3E below)
DPC = Days per Pumpout Cycle [Recommended 90 days]
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design Criteria
6.3.21 Pretreatment Device: Grease Interceptors / Grit Traps / Oil Separators
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Table 6.3-E: Grease Productions Values for Typical FSEs
Menu w/o Fryer,
No Flatware
w/o Fryer,
Flatware
w/ Fryer,
No Flatware
w/ Fryer,
Flatware
Bakery 0.035 0.0455 0.035 0.0455
Bar - Drinks Only 0.005 0.0065 0.025 0.0325
Bar and Grille 0.035 0.0455 0.035 0.0455
BBQ 0.035 0.0455 0.035 0.0455
Buffet 0.035 0.0455 0.035 0.0455
Burger Joint 0.025 0.0325 0.035 0.0455
Cafeteria - Full Serve 0.035 0.0455 0.035 0.0455
Cafeteria - Heat & Serve 0.025 0.0325 0.035 0.0455
Chinese 0.035 0.0455 0.035 0.0455
Coffee Shop 0.005 0.0065 0.025 0.0325
Continental breakfast 0.005 0.0065 0.025 0.0325
Convenience Store 0.005 0.0065 0.025 0.0325
Deli 0.005 0.0065 0.025 0.0325
Donut Shop 0.005 0.0065 0.035 0.0455
Don't know yet 0.035 0.0455 0.035 0.0455
Family Restaurant 0.035 0.0455 0.035 0.0455
Fast Food - Limited Prep 0.025 0.0325 0.025 0.0325
Fast Food - Full Prep 0.035 0.0455 0.035 0.0455
Fried Chicken 0.035 0.0455 0.035 0.0455
Greek 0.035 0.0455 0.035 0.0455
Grocery Store 0.035 0.0455 0.035 0.0455
Ice Cream/Yogurt/Smoothies 0.005 0.0065 0.025 0.0325
Indian 0.035 0.0455 0.035 0.0455
Italian 0.035 0.0455 0.035 0.0455
Mexican 0.035 0.0455 0.035 0.0455
Pizza Restaurant 0.025 0.0325 0.035 0.0455
Pizza Carryout 0.005 0.0065 0.025 0.0325
Multi-unit dwelling 0.005 0.0065 0.025 0.0325
Salads / Healthy Bowls 0.025 0.0325 0.025 0.0325
Sandwich Shop 0.005 0.0065 0.025 0.0325
Seafood 0.035 0.0455 0.035 0.0455
Snack Bar 0.005 0.0065 0.025 0.0325
Steak House 0.035 0.0455 0.035 0.0455
Sushi 0.005 0.0065 0.025 0.0325
Notes:
[1] To determine the correct grease factor, select the menu type, then the correct column for whether there is a fryer and whethe r the
establishment uses disposable or washable plates, glasses, knives, forks, and spoons (flatware).
[2] FSEs that are not open every day, may calculate the number of days open in a 90-day period and use that to calculate the total
amount of grease capacity required and must submit calculation for review.
Source: Brown Grease Supply Study, 2011, Kennedy/Jenks Consultants.
Section 6: Water and Wastewater Design Criteria
6.3 Wastewater Design Criteria
6.3.21 Pretreatment Device: Grease Interceptors / Grit Traps / Oil Separators
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Example calculations are shown below for a Fast Food – Full Prep, with fryer, with
disposable flatware, serving 300 meals per day:
Grease factor from Table 6.3E = 0.035 pounds per meal
Meals per day = 300
Days between pump-outs = 90
Grease Capacity Needed = 0.035 x 300 x 90 = 945 pounds
The correctly sized and selected grease interceptor will have the minimum flow rate determined in
Step 1 and the grease storage capacity calculated in Step 2. Grease interceptors certified to meet
the minimum requirements of ASME A112.14.3 or CSA B481.1 shall have the flow rates and
minimum grease storage capacities as listed in Table 6.3-F below:
Table 6.3-F: Minimum Grease Storage Capacity for
Grease Interceptors
HGI Flow Rate
(GPM)
Minimum Grease Storage Capacity[1]
(lbs.)
20 40
25 50
35 70
50 100
75 150
100 200
Notes:
[1] Minimum grease capacity as required by ASME A112.14.3, PDI G101 and CSA B481.
Grease interceptors claiming grease capacities exceeding the minimum requirements in Table 6.3-
F, shall be reviewed and approved by the City when the manufacturer can demonstrate by third-
party test reports, including the incremental test data, that the interceptor(s) has the capacity
claimed. Upon approval from the City, the grease interceptors proven grease storage capacity may
be used in selecting the sizes and required number of units to satisfy the requirements of the two-
step sizing method in Section 6.3.21.E.2 of this Manual.
F. Laundries
Commercial laundries, laundromats, and dry cleaners shall be equipped with an interceptor to
reduce the quantity of lint and silt that enter the collection system. The system must be of adequate
size and design to allow for cool-down of wastewater so that separation can be more readily
achieved. The interceptor must be installed with a wire basket or similar device, removable for
cleaning, that prevents passage into the drainage system of solids ½-inch (12.7 mm) or larger in
size, string, rags, buttons, or other materials detrimental to the public sewerage system.
G. Car Washes
Where automobiles are washed (including detail shops utilizing hand-wash practices), separators
shall have a minimum capacity of 1000 gallons for the first bay, with an additional 500 gallons of
capacity for every other bay.
H. Automotive Repair Facilities (Garages and Service Stations)
Where automobiles are serviced, greased, or repaired or where gasoline is dispensed, oil or water
separators shall have a minimum capacity of 500 gallons for the first 1000 sq. ft. of area to be
drained, plus 250 gallons for each additional 1000 sq. ft. of area to be drained into the separator.
Section 6: Water and Wastewater Design Criteria
6.4 Construction Plans
6.4.4 Inspections Required
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6.3.22 Inspections Required
New installations or existing pretreatment devices must be inspected by the City of Denton Pretreatment
Program prior to the issuance of a Certificate of Occupancy for new businesses.
6.4 Construction Plans
6.4.1 General
Before any public works construction relative to a development may begin, City staff will verify the
construction plans have been approved. Construction may not begin until the construction plans have been
approved, all materials used for public improvements have been submitted and approved, all fees (including
review and inspection fees) have been paid, all necessary agreements and bonds have been provided, and
a Pre-Construction Conference has been held by the City.
6.4.2 Responsibility
The sealing engineer is responsible for the accuracy, completeness, and conformance of the submitted plans
to City standards. The purpose of the City review is to ensure conformance to City policies and standards.
The City review is limited to facts as presented on the plans submitted. The City has no project engineering
design or quality control review responsibility. The engineer of record certifying the plans is responsible for
the accuracy and completeness of the plan documents. The City reserves the ri ght to require plan
corrections to fit actual field conditions or meet City standards requirements, which are found to be contrary
to or omitted from the plans.
6.4.3 Format
Construction plans shall be digitally drawn on 24-in. x 36-in. size sheets with borders of 22-in. x 34-in., so
half-size reproduced plans will be to half-scale fitting 11-in. x 17-in. sheets. Each sheet shall be legible when
reduced to half-size. Digital copies of the plans shall also be provided.
6.4.4 Plan Requirements
Construction Plans must contain, as a minimum, information listed in the following sections before they can
be approved:
A. General
North arrow, scale, date, and mean sea level elevations of all improvements, based on North
America Vertical Datum 1988 (NAVD 88). Only NAVD 88 shall be used for plan elevations; no
assumed or NGVD 29 elevations. Plans shall be drawn with a horizontal scale of one (1) inch equals
40 feet as a minimum, and appropriate corresponding vertical scale. The plans shall provide a
reference to the elevation benchmark or monument used in the development of the plans. Show
all crossings of existing and proposed underground utilities. Plans shall account for future changes
in topography. The construction plans shall be signed and sealed by a PE licensed by the State of
Texas, prior to bidding the project for construction.
B. Water Systems
Plan sheets must show the horizontal alignment of the proposed water system within street ROWs
and easements, with horizontal control points for location of the ROWs and easements and for
Section 6: Water and Wastewater Design Criteria
6.4 Construction Plans
6.4.4 Plan Requirements
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location of the water system within the ROWs and easements. Sizing of pipe, valves, fittings and
appurtenances must be shown on the plan view. All valves, fittings, fire hydrants, and other
appurtenances must be stationed and given GPS coordinates (with an accuracy of ± six (6) inches)
based on the City of Denton’s grid coordinate system. Profile views of water mains shall be provided
showing proposed grade, pipe material, casing pipe size and thickness (if any), and the location,
elevation and size of any underground conduit or facility to be crossed. Deflections (if any) must be
shown on the plan and profile views, as applicable, with stationing and the degree of deflection.
Approved design deviations (if any) from City Standard Details must be provided. Show all service
lines up to and including the meter can/vault. Service lines do not need to be stationed or have
GPS coordinates. Adequate detail of other planned and existing improvements shall be shown to
indicate planned crossings of utilities, storm drains, and stormwater facilities and potential conflict
points.
C. Sanitary Sewer Systems
Plan sheets must show the horizontal alignment of the proposed sanitary sewer system within street
ROWs and easements, with horizontal control points for location of the ROWs and easements and
for location of the sanitary sewer system within the ROWs and easements. Sizing of pipe, manholes,
fittings and appurtenances must be shown on the plan view. Manhole rim elevations, and pipe “IN”
and “OUT” elevations must be shown. All manholes, fittings, and other appurtenances must be
stationed and given GPS coordinates (with an accuracy of ± six (6) inches). based on the City of
Denton’s grid coordinate system. Every sanitary sewer line shall be profiled. Profile views shall show
proposed grade, pipe material, casing pipe size and thickness (if any), manhole information, and
the location, elevation and size of any underground conduit or facility to be crossed. Approved
design deviations (if any) from City Standard Details must be provided. The plan view shall include
arrows indicating direction of flow in pipe. Show all service lines to and including the public
cleanout. Service lines do not need to be stationed or have GPS coordinates. Adequate detail of
other planned and existing improvements shall be shown to indicate planned crossings of utilities,
storm drains, and stormwater facilities and potential conflict points.
D. Grading
For situations involving proposed grading over existing water or sanitary sewer systems, provide a
grading plan and profile showing the existing and proposed topography in 2-ft. contours. The
grading plan shall consist of contours and spot elevations with water directional arrows to define
the flow patterns.
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Section 7: Streetlight Design Criteria
7.1 Overview
The purpose of Section 7 – Streetlight Design Criteria is to assist developers and engineers in creating an
aesthetic, consistent, and safe lighting plan for our streets, sidewalks, and neighborhoods. This section
outlines the process for design, review, and approval of new lighting projects, as well as criteria for
modernizing existing lighting infrastructure. Streetlights are usually owned by Denton Municipal Electric
(DME) which is a part of the City of Denton (the City), however they may be installed, operated, and
maintained by DME, other electric utilities, or private owners depending on the location. This section of the
DCM has been created to help navigate the process for selecting, permitting, placing, and maintaining
streetlighting throughout the city. This manual does not apply to security, area, pathway, private, or other
lighting not associated with a public road.
This manual cannot cover all the situations that might be encountered, required, or requested in the
construction and installation of streetlighting. Any apparent discrepancy, omission, error, or requirement
necessitating further explanation or interpretation should be referred to DME Engineering (940-349-7117
or 940-349-4173) for further clarification.
The goal of the criteria laid out in this Section 7 is to implement the following guiding principles into the
application of street designs in the City of Denton:
A. Enhance safety of the community for pedestrians and drivers alike
B. Conserve energy by prioritizing efficient lighting design
C. Minimize impact to the environment including light pollution
D. Minimize impact to neighborhoods and residences by reducing light trespass
E. Provide for a uniform and aesthetic look throughout the city
F. Be fiscally responsible through effective application of design principles
7.1.1 Applicability
The existing streetlight installations throughout the City of Denton have been accepted as is at the time of
approval of this manual. Retro-active replacements and upgrades solely for the purpose of bringing existing
lighting up to the standards of this manual are not required. This manual is intended to apply to all new
projects in the City beginning July 1, 2024. (This means the project has been approved/permitted by
Development Services on or after July 1, 2024).
7.1.2 Organization
Section 7 – Streetlight Design Criteria is organized as follows:
A. Overview
B. Requirements
C. Developer & DME Responsibilities
Section 7: Streetlight Design Criteria
7.2 Requirements
7.2.2 General
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7.2 Requirements
7.2.1 General
The City adheres to the guidance of ANSI RP-8 Recommended Practice for Design and Maintenance of
Roadway and Parking Facility Lighting for all highways and streets except for local residential streets with
speed limits of 30 mph or less. ANSI RP-8 acknowledges that vehicle headlights may provide adequate
illumination for slower speeds when the driver has sufficient time for reaction and stopping. As per ANSI
RP-8, Section 11.6.3.1 – ‘When Residential Street Lighting May Not be Needed’, for local residential streets
(e.g., within a residential development) with speed limits of 30 mph or less, street lighting shall be placed
no more than 250 feet apart. A photometric (lighting) study will be required for all new installations except
for local residential streets with speed limits of 30 mph or less.
These standards shall apply to all new streetlight installations, upgrades, replacements, and conversions
from the date of the adoption of these standards onward.
Easement, ROW, and permitting regulations that are not listed in this manual still apply to streetlights. The
developer is responsible for knowing and adhering to any laws and regulations governing development
and construction relating to the work being done.
Developers are responsible for the design, materials, and installation costs of all streetlighting on public
streets within and adjacent to their project. See the Developer and DME Responsibilities Section of this
manual for more specific descriptions of responsibilities. DME will only energize new streetlights after the
installation has been approved by DME. For most lighting installations, following energization, DME will
accept ownership and maintenance of streetlights unless the lighting is located o n a private drive (i.e. the
City has not taken ownership of the street / streetlights) or the lighting is non-standard and will not be
owned or maintained by DME.
Streetlights are not normally metered. The City (or customer in certain cases) is charged a monthly usage
and maintenance fee per light according to the Denton Municipal Utility Rates Manual. This does not apply
to private drives and other private properties where the developer or customer chooses to install lighting
other than the standard city approved options. In such cases, DME will provide a metered service point
only and the customer will be responsible for all installation, maintenance, and fees associated with the
lighting installation in accordance with applicable city codes, ordinances, and utility service standards for
the life of the installation.
City streets and street projects will not be considered complete until adequate streetlighting has been
installed, approved, and energized. For example, for the streets in a new development to be accepted by
and turned over to the City, street lighting must be complete.
7.2.2 Roadway Lighting Requirements
A. Roadway Designations
To determine the proper lighting for a roadway, it is important to determine what type of vehicle
and pedestrian traffic the roadway is meant to accommodate. Roadways may be classed into
several different categories based on these two variables. The lighting requirements are then
applied to provide adequate lighting to mitigate the risks of collision by a vehicle with another
object, vehicle, or pedestrian.
Roadways may be classified as highways and freeways, arterials, collectors, and local roads. In this
section of the DCM, local roads may also refer to auxiliary roadways such as alleys, drives, dead-
ends, and cul-de-sacs. Local roads may be residential streets (providing direct access to homes) or
other local roads providing access to businesses and connecting larger roads together. Local roads
Section 7: Streetlight Design Criteria
7.2 Requirements
7.2.2 Roadway Lighting Requirements
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generally have speed limits of 30 mph or less, while highways, arterials, and collectors will have
higher speed limits. Local roads are further broken down into residential and non-residential streets
in portions of this section to allow flexibility in managing light levels in residential neighborhoods.
Specific road classification and design information may be found in Section 5 – Transportation
Design Criteria of this DCM.
B. Lighting Evaluations and Design
For streetlighting of highways and streets, except local residential streets with speed limits of 30 mph
or less, lighting shall be designed per ANSI RP-8. A photometric (lighting) study will be required
for these new installations. ANSI RP-8 requires that a pedestrian activity classification be made to
determine the required lighting levels. See ANSI RP-8 for further guidance on pedestrian activity
classification and streetlighting design requirements. Additional information may also be found in
the TxDOT Highway Illumination Manual, and AASHTO GL-7, “Roadway Lighting Design Guide”. All
designs adhering to ANSI RP-8 standards shall be verified and documented using appropriate
lighting design software. A licensed PE in the state of Texas shall stamp all lighting designs before
each submittal.
For all local residential streets with speed limits of 30 mph or less, street lighting shall be installed at
intersections, cul-de-sacs, and no more than 250 feet apart for the remainder of the street. Lighting
may be installed along one side of the street, both sides in parallel, both sides alternating, or in the
median. Separation distances should be measured along the centerline of the street. Additional
lighting may need to be considered if there are obstacles or road geometries that cutoff some of
the light. See the Sample Local Residential Streetlighting Layout shown below in Figure 7.1.
When designing or adding streetlights to existing roadways and/or neighborhoods, consideration
should be given to the style and placement of any existing fixtures. New streetlighting shall be
chosen from the available styles that most closely matches the style of the existing lighting in the
area. Historic poles are only approved for specific applications and areas designated as historic
districts or within the Downtown Implementation Plan area.
Section 7: Streetlight Design Criteria
7.2 Requirements
7.2.2 Roadway Lighting Requirements
Design Criteria Manuals 175
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Figure 7.1 Sample Local Residential Street Lighting Layout
(Lights are shown at intersections, cul-de-sacs, and mid-block
when spacing between lights exceeds 250 feet)
C. Intersection and Crosswalks
Intersections have a much higher number of potential conflict points as vehicles and pedestrians
are permitted to cross through normal lanes of traffic. Therefore, additional care is needed when
planning intersection lighting. ANSI RP-8 should be used to design lighting at intersections for
larger, busier streets as stated previously. See Figure 7.2 shown below.
Because of the additional safety concerns for vehicles, cyclists, and pedestrians at crosswalks and
intersections, the following examples (taken from ANSI RP-8) are provided to assist streetlight
design for local streets. While not strictly required, they should be considered as good lighting
practice for these types of locations.
Section 7: Streetlight Design Criteria
7.2 Requirements
7.2.2 Roadway Lighting Requirements
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Figure 7.2 Typical Lighting Schematic for Intersections
D. Roundabouts and Traffic Circles
Like intersections, roundabouts and traffic circles have a higher number of potential conflict points
than normal streets. ANSI RP-8 should be used to design lighting at traffic circles and roundabouts
of larger streets. For local streets, an example of round-about lighting design considerations is
shown below. Some locations may not require as much lighting as shown depending on the size
of the traffic circle. See Figure 7.3 shown below.
Section 7: Streetlight Design Criteria
7.2 Requirements
7.2.2 Roadway Lighting Requirements
Design Criteria Manuals 177
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Figure 7.3 Roundabout Lighting Placement Schematic
E. Railroad Crossings
Railroad crossings are slightly different than normal intersections and require lighting adjustments
accordingly. It is of course, vitally important that drivers are able to see a train that is crossing, and
conversely, that the train engineer has a clear picture of any obstructions while approaching an
intersection. Street lighting at railroad crossings should therefore illuminate the intersection while
not causing glare for the drivers or train engineer. The following figure illustrates the recommended
lighting placement for a railroad crossing. See Figure 7.4 shown below.
Section 7: Streetlight Design Criteria
7.2 Requirements
7.2.3 Installation Requirements
Design Criteria Manuals 178
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Figure 7.4 Railroad Crossing Schematic
7.2.3 Installation Requirements
A. Placement
1. Highways and Streets (except for local residential streets with speed limits of 30 mph or less)
Installation should follow TxDOT recommendations in the TxDOT Highway Illumination
Manual. Where TxDOT requirements do not apply, the streetlight system shall be installed
in the ROW or within public utility easements and poles should be placed approximately 2.5
feet back from curbs and 10 feet back from edge of paving for uncurbed roads or, where
there is sidewalk abutting the curb, approximately 1 foot behind the sidewalk. Deviations of
more than 1 foot in either direction from these requirements must be approved by DME
Engineering.
2. Local Residential Streets (speed limits of 30 mph or less)
The streetlight system shall be installed in the ROW or within public utility easements. Poles
should be placed approximately 2 feet back from the curb of 10 feet from un -curbed
pavement. If a sidewalk abuts the curb, then the pole should be placed approximately 1 foot
behind the sidewalk. In a residential neighborhood, streetlights should be placed within 5
feet of common property lines (e.g. between neighbors).
B. Vertical and Horizontal Clearance
New streetlights should not interfere with existing structures or rights-of-way, including sidewalks,
nor should the placement preclude the ability to perform maintenance on the pole in a safe manner.
See National Electric Safety Code (NESC) Section 234 for specific clearances required for overhead
Section 7: Streetlight Design Criteria
7.2 Requirements
7.2.3 Installation Requirements
Design Criteria Manuals 179
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electric installations. The exception to this requirement is when streetlight arms are mounted
directly to wooden distribution poles.
Proposed trees should be located at least 25 feet from any streetlight location. When installing
new lights in a location with existing trees, consideration should be given to the age and maturity
of the tree and whether it will interfere with the light when it is fully grown. DME will be responsible
for tree trimming around streetlights to preserve the integrity of streetlighting as needed.
Median-mounted poles should be installed at least 20 feet back from an intersection to minimize
the number of vehicle-streetlight collisions due to vehicles and trucks turning too sharply at the
intersection.
In areas predominantly served by overhead electric powerlines, streetlights are usually installed by
attaching streetlight arms to existing wood distribution poles. Care should be given when planning
for lighting in these areas as overhead lines pose a conflict when placing new lighting poles.
Clearances must be maintained for safety. Redesign/relocation of existing overhead power lines
just to accommodate lighting is costly and time consuming. Utilizing existing wood pole locations
and installations on the opposite side of the street are two ideas for additional placement options
in these areas.
C. Approved Fixtures and Materials
The approved streetlight components for each class of roadway are listed below in Tables 7.2-A
and 7.2-B.
Section 7: Streetlight Design Criteria
7.2 Requirements
7.2.3 Installation Requirements
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Table 7.2-A: Approved Luminaires and Hardware by Location
ROADWAY CLASSIFICATION
HIGHWAYS AND
FREEWAYS
(UNLESS OTHERWISE
SPECIFIED BY TXDOT)
ARTERIALS AND LARGE
COLLECTORS ALTERNATE ARTERIALS
AND COLLECTORS
COLLECTORS AND
LOCAL STREETS
EXISTING
RESIDENTIAL
LOCAL STREETS
(ALSO USED IN
HISTORIC
DISTRICTS)
NEW
RESIDENTIAL
LOCAL STREETS
(≤ 30 MPH)
Make Signify Lumec RFL Signify Lumec RFM Gardco Optiform M Signify Lumec RFM Hadco Gardco
Model
RFL-241W112LED-
4K-G2-R2M-UNV-
DMG-ML-RCD7-
API-GY3
RFM-160W48LED-
4K-G2-R2M-UNV-
DMG-ML-RCD7-
API-GY3
OPF-M-A10-840-
2TM-MAR-UNV-
TR7-DGY
RFM-85W24LED-
3K-G2-R2M-UNV-
DMG-ML-RCD7-
API-GY3
C-1891P
RL34AANN2A
SNR7WA3
NNNNSP1
OPF-S-P05-
730-T2M-
AR1-UNV-
SP2-TR7
Wattage 241W LED 160W LED 112W LED 85W LED 69W LED 66W LED
Lumens 30,188 19,489 20,357 8,753 7,734 11,253
Color
Temperature 4000k 4000K 4000K 3000K 3000K 3000K
Light Distribution
Type Type II Type II Type II Type II N/A Light II
Voltage 120 – 277V or
347 – 480V
120 – 277V or
347 – 480V 120-277V 120 – 277V or
347 – 480V 120 - 277V 120 – 277V
B-U-G Rating B4-U0-G4 B3-U0-G3 B3-U0-G3 B3-U0-G3 B2-U5-G4 B2-U0-G2
Pole Type Steel, white
concrete, or wood
Steel, white
concrete, or wood Dark Gray Steel Steel, white
concrete, or wood
Residential -
Concrete
aggregate
Historic – Cast
Aluminum
Steel, square,
gray
Globe Type N/A N/A N/A N/A
Hadco, RL34
Acrylic
Victorian
N/A
Arm Type
8-ft. metal
(specs depend on
pole type)
8-ft. metal
(specs depend on
pole type)
8-foot metal
8-ft. metal
(specs depend on
pole type)
N/A Std-mount, no
arm
Section 7: Streetlight Design Criteria
7.2 Requirements
7.2.3 Installation Requirements
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Table 7.2-B: Approved Pole Types by Location
Part Information Part Description
Highway
and
Freeway 1
Arterial
and
Large
Collector
Collector
and
Local
Street
Existing
Res.
Local
Street
Historic
District 2
New
Res.
Local
Street 3
POLE TYPE – WOOD DISTRIBUTION
N/A
Wood pole.
Various heights, but standard id 35 feet.
DME warehouse item.
Direct buried. Overhead electric service.
Yes Yes Yes Yes No No
Arm - Shakespeare
#OPAR-8-H
8-ft. curved aluminum arm.
- - - - - -
POLE TYPE – WHITE CONCRETE
Lonestar #351101 35-ft. Concrete pole, white color.
Single or double arm available.
DME warehouse item.
Direct buried. Underground electric service.
Yes Yes Yes Yes No No
Arm - Curlee
#2009032TG-Flat Base
8-ft. flat aluminum arm.
- - - - - -
POLE TYPE – CONCRETE AGGREGATE
Lonestar #20004-SJB
(Waterford Series)
20-ft. Concrete aggregate pole.
Post-top luminaire configuration.
Direct buried. Underground electric service.
Legacy – replacement and maintenance only
No No No Yes No No
POLE TYPE – ANTIQUE ALUMINUM
Acuity #PX-CP18-12-
F4-AB3/133T3-ANBK
12-ft. antique, decorative aluminum pole.
Post-top luminaire configuration.
Requires concrete foundation. Underground service.
No No Yes2 Yes2 Yes2 No
POLE TYPE – EMBEDDED STEEL
(Single Arm)
KW Industries
RTSU35-9.0-11-
RAL7043-18S-GS-E
35-foot round steel pole, gray color (RAL7043).
Single arm, direct buried pole. Underground electric service.
Arm included with pole.
Pairs with Gardco Optiform M luminaire.
Yes Yes Yes No No No
(Double Arm)
KW Industries
RTSU35-9.0-11-
RAL7043-28S-GS-E
For use in medians.
35-foot round steel pole, gray color (RAL7043).
Double arm, direct buried pole.
Underground electric service.
Arm included with pole.
Pairs with Gardco Optiform M luminaire.
Yes Yes No No No No
Section 7: Streetlight Design Criteria
7.2 Requirements
7.2.3 Installation Requirements
Design Criteria Manuals 182
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Part Information Part Description
Highway
and
Freeway 1
Arterial
and
Large
Collector
Collector
and
Local
Street
Existing
Res.
Local
Street
Historic
District 2
New
Res.
Local
Street 3
POLE TYPE – BREAK-AWAY STEEL4
(Single Arm)
KW Industries
RTSU35-9.0-11-
RAL7043-18S-GS-
BSC-1.00-SKT
Foundation 30” x 96”
Concrete
35-foot round steel pole, gray color (RAL7043).
Single arm, breakaway base mounted on a poured concrete
foundation.
Underground electric service.
Arm included with pole.
Pairs with Gardco Optiform M luminaire.
Contact DME for poured concrete foundation standards.
Yes4 Yes4 No No No No
Double Arm (Single
Arm)
KW Industries
RTSU35-9.0-11-
RAL7043-28S-GS-
BSC-1.00-SKT
Foundation 30” x 96”
Concrete
For use in medians. 35-foot round steel pole, gray color
(RAL7043). Double arm, breakaway base mounted on a poured
concrete foundation.
Underground electric service.
Arm included with pole.
Pairs with Gardco Optiform M luminaire.
Contact DME for poured concrete foundation standards.
Yes4 Yes4 No No No No
POLE TYPE – BRIDGE-MOUNT STEEL STEEL5
(Single Arm)
KW Industries
RTSU35-9.0-11-
RAL7043-28S-GS-
ATB1-17
Foundation TXDOT
Bridge
For use in medians. 35-foot round steel pole, gray color
(RAL7043). Double arm, breakaway base mounted on a concrete
bridge foundation.
Underground electric service.
Arm included with pole.
Pairs with Gardco Optiform M luminaire.
Yes Yes No No No No
POLE TYPE – STEEL RESIDENTIAL
KW Ind., Part# SSP20-
4-11-DGY GARDCO-
DM10-BC
Foundation 24” x 72”
Concrete
20-ft., dark gray (RAL7043), 4-in. square steel pole.
Drilled for single-luminaire with standard mounting pattern.
Underground service.
Pairs with Gardco Optiform S luminaire.
Contact DME for poured concrete foundation standards.
No No No No No Yes
Notes:
[1] Unless, otherwise specified by TxDOT.
[2] Historic streetlighting is only available for use in designated historic districts.
[3] Speed limits of 30 mph or less.
[4] Steel streetlight poles are only used for highways and roadways where TxDOT or City-approved plans require placement of break-away bases or non-standard mounting heights.
Section 7: Streetlight Design Criteria
7.2 Requirements
7.2.3 Installation Requirements
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D. Historic Lighting
Historic lighting is a modern light fixture with a decorative pole and fixture that give the lighting
the look of early 20th century lighting. Historic lighting has been approved for use only in the
designated historic districts of Denton. All requests for historic lighting within these districts must
be submitted to DME Engineering for design and approval. Historic lighting is not approved for
installations outside of the historic districts. The requesting organization, developer, or agency shall
be responsible for all costs related to the design and installation of historic streetlights.
E. Control System
All new streetlighting in the DME service area shall have a control node installed which, at a
minimum, will turn the light on and off according to ambient light conditions (photocell control)
and shall be compatible with the CityTouch lighting control system. See Table 7.2-C shown below.
Where street lighting is installed by the developer, DME shall provide and install control nodes at
the developer’s expense. DME will commission the control nodes into the CityTouch program.
Where streetlighting is served by other electric utilities than DME, DME does not require or install
control nodes.
Table 7.2-C: CityTouch-compatible control node models
Model Number Voltage (V) Use Function
LLC7290 120 – 277 Cobra head lights Photocell controller
LLC7294 347 – 480 High-voltage cobra head lights Photocell controller
LLC7291 120 - 277 Post-top lights Astro-clock
(GPS location-based timers)
F. Dimming and Light Trespass
The City adheres to ANSI RP-8 lighting levels for all streets except local residential streets with speed
limits of 30 mph or less. Lighting that has been designed to ANSI RP-8 cannot be dimmed without
diminishing the lighting level which, by definition, no longer meets the RP-8 standard. Thus, all
streetlighting that is not in residential neighborhoods with speed limits of 30 mph or less will be
maintained at full brightness.
On local residential streets with speed limits of 30 mph or less, the streetlights may be dimmed by
resident request at specific locations due to light pollution concerns by residents. DME will dim
residential streetlights down as low as 60%.
The City also reserves the right to install house side shields (available only on cobrahead lights) and
make other reasonable modifications to the luminaires to minimize impacts to the residents at the
DME’s discretion.
G. Migratory Birds and Other Flying Species
DME will dim residential streetlights down as low as 50% during select animal migration or activity
periods as specified by the City Environmental Services & Sustainability Department.
Section 7: Streetlight Design Criteria
7.3 Developer and DME Responsibilities
7.3.1 Construction Requirements
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H. International Dark Sky Association
DME installs and maintains two types of streetlight luminaires (light fixtures), post-top and
cobrahead. The cobrahead light fixtures are endorsed by the International Dark Sky Associate (IDA)
which makes recommendations on lighting with minimal up-light. The existing post-top lighting
fixtures are not IDA endorsed, however an acceptable IDA approved alternate is being considered
for all residential streets with speeds less than 30 mph.
7.2.4 Construction Requirements
Streetlight construction (e.g. conduit, wiring, etc.) shall follow the DME Standard Construction Drawings,
stated below:
A. DSL-ARM
B. DSL-STD
C. DSL-12A
D. DSL-20C (Legacy)
E. DSL-35C
F. DSL-20S
G. DSL-35SE
H. DSL-35SE2
I. DSL-35SBK
J. DSL-35SBK2
K. DSL-35SBD
Conduit runs should not exceed 700 feet between pulling locations. When bends total 180 degrees conduit
runs should be limited to 500 feet or less. No run of conduit should have more than 360 degrees of total
bend between pulling points.
The total length of a single lighting circuit at 120V should be less than 1,000 feet, the total length of a single
lighting circuit at 240V should be less than 2,000 feet, and the total length of a circuit at 480V should be
less than 4,000 feet unless circuit design and loading has been validated by engineering.
Additional design information may be found in the TxDOT Highway Illumination Manual.
7.3 Developer and DME Responsibilities
7.3.1 Highways and Streets (except local residential streets with speed ≤ 30 mph)
Developer is responsible for streetlighting design that meets the requirements of ANSI RP -8 for the
appropriate roadway characteristics. A photometric (lighting) study shall be required. The final design must
be approved and stamped by a PE licensed in the State of Texas. Final design must also be approved by
DME Engineering.
Lighting levels, placement, and compliance with ANSI RP-8 must be verified and documented with lighting
design software. At a minimum, documentation shall be provided to DME Engineering showing:
A. Street geometry (width, number of lanes, median size)
Section 7: Streetlight Design Criteria
7.3 Developer and DME Responsibilities
7.3.2 Local Residential Streets (with speed limits ≤ 30mph)
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B. Street classifications (arterial, collector, etc.)
C. Pedestrian activity classification
D. Criteria levels applied (illuminance vs. luminance method, and levels)
E. Lighting placements (median, side, parallel, staggered)
F. Maximum separation distance*
As an alternative to displaying the maximum separation distance as stated in 7.3.1.F above, a layout drawing
of the project may be provided with calculation grid values and/or light level isolines indicating that the
installation meets the applicable requirements.
For TxDOT projects, the design contractor will provide specific lighting requirements, if any. The design
package should dictate where lighting should be placed and what types of poles and fixtures should be
used.
For City initiated projects, the City’s Engineer or their contractor will design the street lighting and submit
to DME Engineering for approval. Once approved, the city’s contractor will perform all civil work, and pull
wiring and install streetlights and poles. DME will provide service point s as needed. DME will also install
and commission control nodes for interconnection with CityTouch.
A monthly maintenance, repair, and usage fee will be charged to the City thereafter for all streetlights on
public streets per current DME rates.
7.3.2 Local Residential Streets (with speed limits ≤ 30mph)
The Developer (or DME if DME is responsible for the given project) is responsible for the design and layout
of streetlights at all intersections, cul-de-sacs, and no more than 250 feet between. DME Engineering shall
approve the final design. Once the project is approved and permitted, the Developer is responsible for
providing all civil work including grading, trenching, installation of conduit and pull-boxes, etc.
DME is responsible for installation of wire, streetlights and poles, and service points. DME will charge an
initial installation cost to the developer based on the number of lights.
A monthly maintenance, repair, and usage fee will be charged to The City thereafter for all streetlights on
public streets per current DME rates.
For City initiated projects, the City’s Engineer or their contractor will design the street lighting and submit
to DME for approval. Once approved, the city’s contractor will perform all civil work, and pull wiring and
install streetlights and poles. DME will provide service points as needed. DME will also install and
commission control nodes for interconnection with CityTouch.
For private streets and drives (where the City of Denton does not take ownership of the roadway or
streetlights), one of the following will occur:
A. If non-standard lights are installed, DME will provide a metered service point. Developer is
responsible for installation of entire streetlighting system. Designated customer (individual, HOA,
etc.) will be responsible for monthly power costs and all maintenance. OR
B. If standard DME lighting is installed, Developer is responsible for all civil work (grading, trenching,
installation of conduit, etc.) and installation of poles and streetlights. DME will pull wires and
connect the lights at the Developer’s expense. Designated customer (individual, HOA, etc.) will be
responsible the monthly streetlight power and maintenance rates. OR
C. Exceptions to this rule must be agreed upon by all parties in a formal agreement.
Section 7: Streetlight Design Criteria
7.3 Developer and DME Responsibilities
7.3.4 Streetlighting in Non-DME-Served Areas
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7.3.3 Streetlighting in Non-DME-Served Areas
Standard streetlights have been approved by the City as listed in the General Requirements section of this
manual. Electric utilities other than DME may or may not be able to provide the same luminaires. Non -
standard lights will not be maintained by DME or the City. DME will provide, install, maintain, and repair
standard the City streetlights at the Developer’s expense. The electric service provider will charge the City
according to the rates agreed upon between the City and the electric service provider.
For streets in non-DME service territories, Developer should coordinate with the electric utility, DME, and
the City at the earliest stage of development to determine and agree upon the following:
A. Developer, City/DME, and Customer responsibilities
B. Service points and project design
C. Mode of disconnect for safe maintenance (e.g. in-line fuses, etc.)
D. Mode of billing (metered usage, monthly rate, etc.)
E. Designated customer/developer responsible for fees
F. Other concerns as applicable
7.3.4 Customer/Citizen Requests for addition/removal of Streetlighting
Streetlights managed by DME are funded through the City’s Capital Improvement Projects (CIP) process.
As concerns are identified and provided to DME via citizen comments, staff input, and/or City Council
direction the requests are directed to DME Engineering for technical evaluation. The technical evaluation
is to determine if the modifications would provide added safety and visibility according to national and
local standards and ordinances. Light pollution/intrusion, cost, feasibility, and aesthetic value are also
considered. At the conclusion of the technical evaluation, DME Engineering submits a recommendation for
or against inclusion of the project in the CIP.
DME will maintain the list of all requested modifications and prioritize those that have been recommended
for inclusion within the upcoming CIP. Some or all of the highest priority projects will be programmed into
the upcoming budget based on availability of funds.
Requests for dimming will be considered in residential areas, and in coordination with the City’s
Environmental Services & Sustainability Department, DME may dim streetlights in residential developments
to no lower than 50% brightness. Cobrahead streetlights along other local, collector, and arterial streets
may not be dimmed due to safety and regulatory requirements.
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Section 8: Environmentally Sensitive Areas
Design Criteria
8.1 Overview
The purpose of Section 8 - Environmentally Sensitive Areas (ESAs) Design Criteria is to provide the technical
design criteria needed to achieve compliance with DDC Subchapter 7, Section 7.4. The goal is to provide
basic guidance for implementing certain components of ESA plans, such as ESA Field Assessments. While
the intent of this section is to assist applicants and developers with ESA requirements, full responsibility and
liability for proper design and compliance with DDC Section § 7.4 remains with the developer or applicant.
Users of this Manual should be knowledgeable and experienced in environmental surveys, inventorying and
restoration (See the basic requirements for a qualified person in this section).
This section does not provide complete guidance for Alternative ESA Plans, as those plans are developed
through a discretionary zoning process, due to special circumstances or conditions that apply to the parcel
for which the deviation is sought. The Alternative ESA Plan procedure is described in DDC Section § 2.8.4.
The following documents govern the design criteria in this section and in the event of a conflict between
any of these documents, the following order of precedence applies:
A. The Denton Development Code;
B. Floodplain Development Checklist;
C. ESA Field Assessment Checklist;
D. Alternative Environmentally Sensitive Area Checklist;
E. The iSWM Landscape Technical Manual; and
F. The National Wetland Plant List.
8.2 ESA Identification
8.2.1 The Official ESA Map
A. To locate potential ESAs, the applicant shall use the City of Denton’s Official ESA Map.
B. The legend in the Official ESA Map displays the types of ESAs and their designations.
1. The City recognizes four types of ESAs, as detailed further in Appendix D of this Manual:
a. Cross Timbers Upland Habitat;
b. Water Related Habitat;
c. Riparian Buffer ESA; and
d. Floodplain ESA.
2. ESAs can have one of two following designations
a. Designation Confirmed
ESA assessments expire after 24 months or if the natural conditions of the ESA have
been significantly altered; the applicant shall check the date that the assessment was
approved to ensure that the current designation is correct
Section 8: Environmentally Sensitive Areas Design Criteria
8.3 ESA Field Assessments
8.3.3 ESA Field Assessor
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b. Not Assessed or Assessment Expired
C. Areas determined to be ESAs during field assessments are added to the Official ESA Map.
D. Areas determined not to be ESAs during field assessments may potentially be removed from the
Official ESA Map.
E. Field assessments are required when there is reasonable evidence that ESAs, as depicted on the
Official ESA Map, may not be accurate. ESA field assessments that require map adjustment shall
supersede the Official ESA Map in determining what areas of a prop osed development are subject
to the requirements of Section 7.4 (Environmentally Sensitive Areas) of the DDC.
8.3 ESA Field Assessments
8.3.1 ESA Field Assessor
ESA features shall be identified during the ESA Field Assessment by a qualified person . Minimum
requirements to be considered a qualified person are:
A. Have a bachelor’s degree in ecology or similar field of study;
B. Be a certified/trained wetland scientist; or
C. Have similar qualifications in plant identification, soil classification, and hydrology.
1. The City accepts professional licenses and certifications such as Professional Wetland
Scientist (PWS), Wetland Professional in Training (WPIT), and continuing professional
education courses from applicable programs.
8.3.2 ESA Forms
All ESA submittals shall utilize the City’s Assessment Forms:
A. Cross Timbers Upland Habitat Assessment Form
B. Floodplain ESA Assessment Form
C. Riparian Buffer ESA Assessment Form
D. Water-Related Habitat Assessment Form
8.3.3 ESA Field
ESA Field Assessments shall contain, at a minimum:
A. Assessor qualifications;
B. Comprehensive reports for each ESA type and feature assessed, pursuant to the ESA Assessment
Form for each type of ESA present on the project;
C. A project narrative with details of the assessment, including, but not limited to:
1. A brief description of the project’s nature
2. Descriptions and locations for ESAs identified on the Official ESA Map
3. Descriptions and locations of any ESAs determined to be present
a. Include detailed reasoning as to why ESA features were identified
Section 8: Environmentally Sensitive Areas Design Criteria
8.4 ESA Preservation Requirements
8.4.1 ESA Inspections
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b. Include colored photographs as supporting evidence
4. Location and boundaries of areas misidentified as ESAs by the City’s Official ESA Map
a. Include detailed reasoning as to why the Official ESA Map is incorrect
b. Include colored photographs as supporting evidence
D. Shapefiles identifying both confirmed ESAs, and ESA locations that should be removed. The
following geographic information shall be used:
1. Geographic Coordinate System: GCS North American 1983
2. Datum: D North American 1983
3. Prime Meridian: Greenwich
4. Projected Coordinate System: NAD 1983 State Plane Texas North Central FIPS 4202 Feet
5. Projection: Lambert Conformal Conic
E. A site map or series of maps, that delineate the boundaries and types of ESAs as indicated on the
Official City of Denton ESA Map; and
F. A site map that delineates the boundaries and types of ESAs that were assessed; this may differ
from the Official ESA Map.
1. Indicate the reach of each assessment and locations of photographs taken on a map; this
may be its own map.
8.4 ESA Preservation Requirements
Where ESAs are identified, whether through field assessments or an existing, confirmed designation, ESA
protection must be installed.
A. ESA protection shall consist of safety or other protective fencing established at the perimeter of
any ESAs. Where a tree that qualifies for preservation is located near the ESA perimeter, protective
fencing shall be extended to encompass the tree within ESA boundaries. Where ESA protective
fencing has been extended to encompass preserved trees, it shall be installed at the tree’s dripline.
B. Land-clearing to allow for the installation of ESA protection fencing shall occur upslope of the
ESA perimeter (that is, on the outside perimeter), and shall not exceed a width of four feet. It shall
not encroach into the dripline of any tree to be protected.
C. Protective fencing should be a minimum of four (4) feet in height and consist of plastic safety
fencing or other approved fencing material. Protective fencing shall be supported by posts with a
maximum spacing of eight (8) feet.
D. Protective fencing shall be placed downslope of any perimeter controls for erosion and
sedimentation.
8.4.1 ESA Inspections
A. Initial Inspections
1. An initial inspection shall be conducted prior to: approval of permits, issuance of a Notice-
to-Proceed, or any commencement of land disturbing activities.
2. ESA protective fencing shall be inspected against corresponding site plans for proper
Section 8: Environmentally Sensitive Areas Design Criteria
8.4 ESA Preservation Requirements
8.4.1 ESA Inspections
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placement and installation.
B. Routine Inspections
1. To ensure compliance with ESA criteria, ESA inspections shall be conducted after land-
disturbing activities have commenced, and may be conducted during all phases of
development, including:
a. Cut and fill;
b. Demolition;
c. Clearing and grading;
d. Grubbing;
e. Stockpiling;
f. Installation of utility infrastructure;
g. Construction; and
h. Vertical building.
2. Routine inspection items shall include maintenance, repair, and replacement of ESA
protective fencing. Damaged ESA fencing shall be repaired or removed and replaced during
all phases of development until final inspection.
3. During development, access to the ESA shall be prohibited and the ESA shall be preserved
in its original state.
4. The disposal of any waste material into the ESA is prohibited.
5. Siltation or sedimentation to the ESA is prohibited and must be addressed in a timely manner.
a. Siltation or sedimentation impacting up to 0.10 acres of any ESA must be removed by
hand or equivalent method, as approved by the City.
b. Siltation or sedimentation impacting 0.10 acres or more of any ESA must be addressed
through an Alternative ESA Plan.
6. The permanent loss of any native vegetation or other ESA features is prohibited.
a. If the loss of any native vegetation or ESA feature affects up to 0.10 acres of any ESA :
i. The ESA must be returned to its previous state through in-situ restoration; and
ii. A restoration plan shall be provided.
These requirements apply when development activities result in the loss of two (2) or
less trees, protected as per Section 8.4.A of this Manual.
b. If the loss of any native vegetation or ESA feature affects 0.10 acres or more of any ESA,
the developer may be required to initiate one (1) of the following compliance activities,
based on the extent of damage to the ESA(s) and staff discretion:
i. Cease all development activities and provide a restoration plan to the City for
approval; or
ii. Cease all development activities and pursue mitigation through an Alternative ESA
Plan.
These requirements apply when development activities result in the loss of three (3) or
more tree protected as per Section 8.4.A of this Manual.
Section 8: Environmentally Sensitive Areas Design Criteria
8.5 Restoration Plans for Permitted Uses and Activities
8.5.2 Restoration Plan Requirements
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8.5 Restoration Plans for Permitted Uses and Activities
8.5.1 Restoration Plan Requirements
Permitted uses and activities for each ESA are described in DDC Sections §§ 7.4.6-7.4.8. For permitted uses
and activities, the applicant shall provide a restoration plan which, at a minimum, includes:
A. Locations and descriptions of any areas within the ESA that will require restoration ;
B. Locations and descriptions of temporary stabilization measures;
C. Descriptions of restoration activities including, but not limited to:
1. Erosion minimization;
2. Native plant restoration;
3. Invasive vegetation removal, etc.
D. Schedule or timeline for restoration activities; and
E. Descriptions and locations of permanent seed mixes and/or plantings.
8.5.2 Restoration Activities and Alternative ESA Plan Mitigation
This subsection applies to approved Restoration Plans and mitigation for Alternative ESA Plans.
A. Restoration shall be initiated immediately whenever development activities have permanently or
temporarily ceased within the ESA, or as otherwise specified in the schedule set by the Restoration
Plan.
1. Development activities have permanently ceased when land-disturbing activities within the
ESA have been completed.
2. In the context of this provision, “immediately” means as soon as practicable, but no later than
the end of the next workday, following the day when development activities have temporarily
or permanently ceased.
B. Alternative ESA Plan Mitigation, unless alternatively specified in the approved plan, shall also be
initiated immediately whenever development activities have permanently or temporarily ceased
within the ESA
1. Mitigation for disturbed ESAs, by area, must be one-to-one by ESA type.
C. Restoration and/or mitigation shall be completed prior to close-out or issuance of final Certificate
of Occupancy.
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Section 9: Design Deviations
9.1 Overview
9.1.1 General
All developments within the City and its extraterrestrial jurisdictions shall conform to the design criteria
established in this DCM. In the event that a development cannot comply with the design criteria established,
a design deviation process is used to evaluate, document, and approve proposed alternative methods.
Any deviation from the required design criteria for design of facilities outlined in this DCM must be
submitted as a design deviation request to the City’s Engineer and Department Reviewer, prior to
incorporating it into the final design of a project.
9.2 Design Deviation Procedure
9.2.1 Request for Design Deviation Submittal and Processing
A. All design deviation requests must be submitted as a formal request to Development Project
Facilitation using the ‘Request for Design Deviation Form’ included in Appendix B, along with
supporting documentation.
1. The ‘Request for Design Deviation Form’ shall be filled out completely with exception of the
portions noted as “For Use by City”.
2. Supporting documentation shall include:
a. All pertinent information on the facilities involved or to be involved. The specific portion
of this DCM, policies, or design standard(s) for which a design deviation is sought;
b. Description(s) of all other design alternatives which the applicant has evaluated in
attempts to comply with the design criteria prior to the request for design deviation;
and
c. A statement that provides justification for the requested design deviation and how it is
the necessary and optimal solution when compared with reasonable alternatives for the
scenario presented.
3. Design deviation requests that do not contain the required Request for Design Deviation
Form and supporting documentation are incomplete and will not be reviewed.
B. The request and supporting documentation shall be submitted concurrently with Civil Engineering
Plans, Zoning Compliance Plans, Planned Development, or Specific Use Permit submittal.
9.2.2 Criteria for Granting of Design Deviation
A. The review of a design deviation request by the City’s Engineer and Department Reviewer shall
assess whether the request:
1. Clearly demonstrates an exceptional hardship which prevents the design criteria from being
met. This hardship cannot be solely self-imposed and should be based upon physical
characteristics of the property, environmental conditions, or existing conditions created by
surrounding development;
Section 9: Design Deviations
9.3 Revocation of an Approved Design Deviation
9.1.1 General
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2. Is not detrimental to the public welfare;
3. Does not adversely impact the operations of the system or the public facility in question;
4. Is supported by a signed and sealed engineering analysis performed by a PE licensed in the
State of Texas, if requested by the Engineering Department; and
5. Shall not be solely to mitigate a financial hardship.
B. The decision of the City’s Engineer and Department Reviewer is guided by the criteria for approval,
but is ultimately discretionary based on their engineering judgment and professional experience.
C. All approved design deviation requests shall be signed by the City’s Engineer and Department
Reviewer, before implementation.
D. The decision of the City’s Engineer and Department Reviewer to grant a design deviation shall not
relieve the applicant’s Engineer of the professional obligation and responsibility to ensure any
approved alternatives to the use of the material, design, or method of construction are fit for the
intended purposes of the facilities at issue.
E. If a design deviation request is denied by the City’s Engineer and Department Reviewer, the
applicant may consider reviewing alternatives and resubmitting the application with more
information as is deemed necessary, for re-evaluation by the City’s Engineer and Department
Reviewer.
9.3 Revocation of an Approved Design Deviation
9.3.1 Applicability and Procedure
A. An approved design deviation request may be revoked by the City’s Engineer and Department
Reviewer, if:
1. The supporting documentation that the City’s Engineer and Department Reviewer used to
review and approve the design deviation request is materially altered or updated. Any
individual or entity that receives an approved design deviation request must provide the
City’s Engineer and Department Reviewer with any change in plans or conditions to the
project that affect the requested deviation as soon as practicable after any such change
occurs. Failure to provide these updates may result in design deviation revocation by the
City.
2. The applicant is shown to have provided inaccurate or incomplete information during review
of the design deviation request.
3. The City determines there is a failure to comply with any term, condition, or requirement
applicable to a design deviation;
B. A decision to revoke a design deviation is effective immediately. Notice of the decision shall be
communicated to the applicant.
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Appendix A: Example Stormwater Facility Checklists
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INSPECTION CHECKLIST FOR SIMPLE DETENTION BASIN
Facility Name: Facility Agreement Number:
Basin/Pond Number: Inspected By: Date:
Type of Inspection: Annual , Quarterly , Monthly , Routine , or Storm Event , (# days since event )
Basin Conditions:
1. Is there standing water or wet spots? Yes No Comments
2. Does sides or bottom show signs of erosion, settling, cracking, etc? Yes No Comments
3. Does dam or emergency spillway show signs of erosion, settling,
cracking, or other problems Yes No Comments _____________________________________
4. Is there evidence of animal burrowing in dam? Yes No Comments
5. Is there evidence of changes in shape or volume of basin? Yes No Comments
6. Do vegetated areas need mowing? Yes No Comments
7. Are there trees or woody growth in dam? Yes No Comments
8. Are there areas that need to be re-vegetated? Yes No Comments
9. Is there any accumulation of silt, trash, debris or litter in the basin? Yes No Comments
10. Are there any other basin maintenance activities needed? Yes No Comments
Structural Components:
1. Are pipes, channels, trash racks, etc. free of obstructions? Yes No Comments
2. Are pipes, spillway or trash racks in need of repair? Yes No Comments
3. Is the low flow or trickle channel in need of repair? Yes No Comments
4. Is the outfall channel in need of repair? Yes No Comments
5. Are there any other structural maintenance activities needed? Yes No Comments
Plan for correcting deficiencies: Signature:
Date:
Owner’s Representative
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ENGINEER’S CHECKLIST FOR STORMWATER
FACILITY MAINTENANCE AGREEMENT
Please attach additional sheets as necessary for comments and descriptions. Fit all sheets to 8½” x 11”.
ORGANIZATION INFORMATION
1. Company (Applicant) Address:
2. Contact’s Information:
Contact Name
Mailing Address
Telephone
Number(s) Email
3. Execution Information:
Signatory’s Name
Mailing Address
Telephone Number(s)
Email
4. Property Location:
(Note: If the property has not been addressed, please enter the legal description)
5. Associated Plat Numbers:
(Note: if request is related to multiple plat applications, please list each individually)
6. Associated Building Permit Numbers:
(Note: if request is related to multiple permits, please list each individually)
AGREEMENT & ATTACHMENT INSTRUCTIONS
If the property owner is a corporation, the agreement must be signed by a person who is duly authorized to bind the corporation including, but not limited to, a
President or Vice President. . If a partnership, the agreement must be signed by the managing partner. If the applicant is a sole proprietor, he/she signs the
agreement on behalf of him or herself. Additionally, for corporations and partnerships, a copy of the Articles of Incorporation, showing signature authority
for whoever signs the agreement must also be submitted (Note: Applicants may also submit a board resolution or power of attorney authorizing an agent
or assign to sign on behalf of the property owner. The agreement must be completely filled out and three copies submitted to the Planning and Development
Department. Signatures on all three agreement drafts must be original and notarized. Lastly, please submit a copy of the deed for the noted property.
NOTE: Agreement and all attachments should be submitted on 8 ½” x 11”.
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Yes No N/A Comments/Descriptions Page 2 of 3
1. Legal Agreement – Standard agreement form provided by
the City.
2. Exhibit “A” - Legal Description (Attached)
A. Metes and Bounds.
B. Surveyor’s Drawing, with seal affixed and marked as
“Drainage Easement”.
C. Preliminary Plat.
3. Exhibit “B” - Design Plan and Specifications (Attached)
A. Design Calculations – in accordance with iSWM.
B. Schematic Plan (See Example Detention Plan Schematic)-
prepared in accordance with approved construction plans:
• Plan View showing critical structural elements .
• Critical structural elements are clearly labeled in layman terms.
• Profile including a longitudinal section showing all critical
structural elements with elevations.
• Cross-sections as needed to show size and general grading.
NOTE: All Schematics should be submitted on 8 ½” x 11”.
C. Landscaping shown per approved Landscape Plans.
4. Exhibit “C” - Operations and Maintenance Plan (Attached)
A. Routine Maintenance Specifications:
1. Mowing as needed to control weeds and woody plants.
2. Trash removal from critical structural elements.
3. Additional maintenance.
B. Non-routine Maintenance Activities:
1. Bank repair and stabilization.
2. Re-vegetation - required when 30% or more of area is
unprotected.
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Yes No N/A Comments/Descriptions Page 3 of 3
3. Sediment removal from the detention/retention facility when:
• Detention basin – when water depth is reduced 25%
or more, or basin does not drain within 72 hours.
• Retention pond – when water depth is 4’ or less.
• Sediment traps/forebay – when depth is reduced by 50% or more.
4. Structural repair/replacemen t for all damaged or deteriorated
structures, trickle channel, trash rack, etc.
5. Mechanical equipment repairs.
6. Other maintenance Activities.
5. Exhibit “D” - Maintenance Checklist *
A. Covers ordinary needs, in layman terms.
B. Structural components labeled consistent with Schematic Plan.
*See attached Inspection Checklist for Detention Basin
NOTE: All Exhibits should be submitted on 8 ½” x 11”.
I certify that this Storm water Facility Maintenance Agreement, checklist, required attachments, and additional comments, was
prepared under m y responsible supervision and that the information presented on this checklist and attachments is correct to
the best of m y k nowledge. I also understand that an acceptance of this plan b y the City does not waive any City standards or
requirements unless a specific waiver request has been submitted and approved.
(seal)
Signed Date _
Print Name:
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Appendix B: Design Deviation Request Form
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Note: Request the fillable Deviation Request form from your Facilitator.
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Appendix C: Poles and Luminaires - Standard
Lighting Fixtures
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Figure C.1: Residential Lighting – 20-ft. concrete aggregate pole woth post-top luminaire
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Figure C.2: General Street Lighting – Wood (distribution) pole with single-mast arm
and cobra head luminaire
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Figure C.3: General Street Lighting – 35-ft. white concrete pole with single or double-mast arms
and cobra head luminaire
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Figure C.4: Historic District Lighting – 12-ft. concrete aggregate pole woth post-top luminaire
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Figure C.5: Alternate General Streetlighting – 35-ft. dark gray steel pole with single or double mast
arms and new cobra head luminaire.
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Appendix D: Types of Environmentally
Sensitive Areas
The City of Denton has identified four distinct ESAs - Floodplains, Riparian Buffers, Water-Related Habitat,
and Cross Timbers Upland Habitat. Native plants associated with each ESA are listed below. A complete list
of Native Plants is included in Appendix E.
A. Floodplain ESAs exist on the terraced banks surrounding waterways where the land is subject to
flooding. The City of Denton uses the most current FEMA Flood Insurance Rate Map (FIRM) to
define boundaries of protected Floodplain ESAs. Areas designated as 1% Annual Chance Floodplain,
labeled on the FIRM as Zone A or Zone AE, would be classified according to existing conditions as
developed or undeveloped floodplains. Areas identified as undeveloped floodplains become
protected Floodplain ESAs. Floodplain ESA habitat is often an extension of the more sensitive
Riparian Buffer. Typical Floodplain ESA habitat is dominated by tree species that can tolerate
intermittent flood events.
B. Riparian Buffer ESAs are adjacent to bodies of water such as wetlands, streams, rivers, ponds and
lakes. A healthy functioning Riparian Buffer will have a mix of woody and herbaceous plants.
Streams, creeks, and rivers are classified by their duration of flow; there are three types:
1. Perennials flow continuously except during severe drought.
2. Intermittent flow only for a portion of the year seasonally or after rainfall.
3. Ephemerals only flow in direct response to rainfall and will often be dry.
C. Water-Related Habitat ESAs are split into four categories: wetlands, bottomland hardwood forests,
springs, and deepwater habitats. These areas are typically found in low-lying areas near bodies of
water but can also be isolated low-lying areas that meet characteristics of water-related habitats.
These characteristics will likely include hydric soils, signs of hydrology, and hydrophytic vegetation.
1. Wetlands can be isolated or adjacent and will have all three wetland indicators present: hydric
soils, hydrology, and hydrophytic vegetation. Adjacent wetlands are connected to a
jurisdictional water body, such as a lake or river, and are subject to federal regulation under
the Clean Water Act; isolated wetlands are not connected to surface water bodies and are
regulated at the state or city level.
a. An area shall be classified as a wetland if it meets the Army Corps of Engineers three
parameter technical criteria as outlined in the Corps of Engineers 1987 Wetlands
Delineation Manual (Section D. Routine Determinations).
b. The recommended routine method assumes sufficient hydrology and hydric soils if the
area in question has over 50% vegetative cover of hydrophytic (facultative-wet and/or
obligate as listed in the National Wetland Plant List (NWPL), Great Plains Region, and a
clearly defined boundary between the hydrophytic and upland plant communities.
c. Permitted water quality ponds, roadside ditches, and ponds fed by wells or other
sources of artificial hydrology are not considered wetlands.
d. The Wetlands Classification System (WCS) includes five major Systems: Marine,
Estuarine, Riverine, Lacustrine, and Palustrine. The first four include both wetlands and
deepwater habitats, but the Palustrine only includes wetland habitats. In North Central
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Texas, the predominant wetland types are Riverine, Lacustrine and Palustrine , and are
detailed in Table 9-A below.
Table D-1: Predominant Wetland Types of North Central Texas
Wetland Type Major Characteristics
Riverine Wetlands and deepwater habitats within a stream or river channel; includes
oxbow lakes and sloughs; periodically influenced by flooding
Lacustrine Wetlands and deepwater habitats associated with large lakes and reservoirs;
situated in basins that lack significant tree or shrub cover
Palustrine All non-tidal wetlands dominated by trees, shrubs, or persistent plants;
includes Bottomland hardwood forests, which is the most widespread type of
wetland in Texas and includes trees like pecan, sugarberry, and black willow.
2. Bottomland Hardwood Forest ESAs consist of deciduous forested wetlands and river
bottoms. Denton defines this habitat as areas containing at least 50 percent of native trees
and understory vegetation typically found in a bottomland hardwood forest.
3. Springs are points of natural groundwater discharge that produce flow, a pool of water, or
maintain hydrophytic plant communities (refer to Facultative-wet or Obligate plant species
as listed in the in the National Wetland Plant List (NWPL), Great Plains Region. Physical
indicators include pooling of water, hydrophytic plants, or the presence of a water temperate
gradient in a creek or pool.
4. Deepwater habitats are permanently flooded lands lying below the deepwater boundaries of
wetlands. Deepwater habitats include environments where surface water is permanent and
often deep, so that water, rather than air, is the principal medium within which the dominant
organisms live, whether or not they are rooted in, or attached to, the substrate. As in
wetlands, the dominant plants are hydrophytic.
Wetlands and deepwater habitats are defined separately because traditionally the term wetlands
has not included deep, permanent water; however, both must be considered an ecological
approach to classification. The boundary between wetland and deepwater habitats in the riverine
and lacustrine systems lies at a depth of 2 meters (6.6 feet) below water; however, if emergent,
shrubs or trees grow beyond this depth, their deep-water edge is the boundary.
D. Cross Timber Upland Habitat ESA are deciduous forest interspersed with prairie grasses. It can be
split into four vegetative sub-regions. The predominate sub-region found in Denton, TX is the
Eastern Cross Timbers. The Eastern Cross Timbers is dominated by Post Oaks and Blackjack Oaks.
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Appendix E: Native Plants for ESAs
Table E-1: Native Plants List – Canopy Trees
Common Name Botanical Name
Red maple Acer rubrum
Texas buckeye Aesculus arguta
Pecan Carya illinoiensis
Texas hickory (Black hickory) Carya texana
Net-leaf hackberry Celtis reticulata
Desert willow Chilopsis linearis
White ash Fraxinus americana
Green ash Fraxinus pennsylvanica
Texas ash Fraxinus texensis
Black walnut Juglans nigra
Ashe juniper (Mountain cedar) Juniperus ashei
Eastern red cedar Juniperus virginiana
Sweetgum Liquidambar styraciflua
Texas red oak Quercus buckleyi
Escarpment live oak Quercus fusiformis
Bur oak Quercus macrocarpa
Blackjack oak Quercus marilandica
Chinquapin oak Quercus muehlenbergii
Shumard oak (Red oak) Quercus shumardii
Bigelow oak Quercus sinuata var. breviloba
Post oak Quercus stellata
Live oak Quercus virginiana
Black willow Salix nigra
Western soapberry Sapindus saponaria var.drummondii
Chittamwood (Gum bumelia) Sideroxylon lanuginosum
Winged elm Ulmus alata
American elm Ulmus americana
Cedar elm Ulmus crassifolia
Slippery elm Ulmus rubra
Prickly ash (Texas hercules club) Zanthoxylum hirsutum
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Table E-2: Native Plants List – Small Trees and Shrubs
Common Name Botanical Name
White buckeye (Texas buckeye) Aesculus arguta
Common beebush (Whitebrush) Aloysia gratissima
Indigobush (False Indigo) Amorpha fruticosa
Roosevelt-weed Baccharis neglecta
Argarita (Mahonia) Berberis trifoliolata
American beautyberry Callicarpa americana
Buttonbush Cephalanthus occidentalis
Eastern redbud Cercis canadensis
Texas redbud Cercis canadensis var. texensis
Roughleaf dogwood Cornus drummondii
Downy hawthorn Crataegus mollis
Greenhawthorn Crataegus reverchoni
Common persimmon Diospyros virginiana
46 Elbowbush Forestiera pubescens
Carolina buckthorn Frangula caroliniana (Rhamnus caroliniana)
Possum-haw Ilex decidua
Yaupon Holly Ilex vomitoria
Texas Walnut (Nogalito, Little walnut) Juglans microcarpa
Mock orange Philadepphus pubescens
Chickasaw plum Prunus angustifolia
Oklahoma plum (Sand plum) Prunus gracilis
Mexican plum Prunus mexicana
Hog plum Prunus rivularis
Hoptree Ptelea trifoliata var. mollis
Flameleaf sumac Rhus copallinum
Smooth sumac Rhus glabra
Buffalo currant Ribes aureum
White prairie rose Rosa foliolosa
Elderberry Sambucus nigra var. canadensis
Eve`s necklace Sophora affinis
Coralberry Symphoricarpos orbiculatus
Mexican buckeye (Texas buckeye) Ungnadia speciosa
Farkleberry Vaccinium arboreum
Rusty blackhaw Viburnum rufidulum
Arkansas yucca Yucca arkansana
Lotebush Ziziphus obtusifolia
Peppervine Ampelopsis arborea
Heartleaf ampelopsis Ampelopsis cordata
Pipevine Aristolochia tomentosa
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Table E-2: Native Plants List – Small Trees and Shrubs
Common Name Botanical Name
Rattan vine Berchemia scandens
Trumpet vine Campsis radicans
Ballonvine Cardiospermum halicacabum
Cowitch (Ivy-treevine, sorrelvine) Cissus incisa
Old-man's-beard Clematis drummondii
Bluebill (Leather-flower) Clematis pitcheri
Carolina snailseed Cocculus carolinus
Sharp-pod morning glory Ipomoea cordatotriloba var. cardatrtriloba
Cotton morning glory Ipomoea cordatotriloba var. torreyana
Coral honeysuckle Lonicera sempervirens
Virginia creeper Parthenocissus quinquefolia
Blackberry Rubus oklahomus
47 Dewberry Rubus trivialis
Greenbriar Smilax bona-nox
Bristly greenbriar Smilax tamnoides
Summer grape Vitis aestivalis
Mustang grape Vitis mustangensis
Riverbank grape Vitis riparia
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Table E-3: Native Plants List – Grasses
Common Name Botanical Name
Elliott's bentgrass (Annual tickle grass) Agrostis elliottiana
winter bentgrass (Tickle grass) Agrostis hyemalis
Big bluestem Andropogon gerardii
Bushy bluestem Andropogon glomeratus
Splitbeard bluestem Andropogon ternarius
Broomsedge bluestem Andropogon virginicus
Oilfield threeawn (Prairie threeawn) Aristida oligantha
Purple threeawn Aristida purpurea
Silver bluestem Bothriochloa laguroides
Sideoats grama Bouteloua curtipendula
Blue grama Bouteloua gracilis
Hairy grama Bouteloua hirsuta
Texas grama Bouteloua rigidiseta
Red grama Bouteloua trifida
Erect brachyelytrum Brachyelytrum erectum
Downy brome Bromus pubescens
Buffalograss Buchloe dactyloides
Broadleaf woodoats (Inland sea-oats) Chasmanthium latifolium
Hooded windmillgrass (Crowfoot grass) Chloris cucullata
Short-spike windmillgrass Chloris subdolichostachya
Tumble windmillgrass Chloris verticillata
Feather finger grass (Showy chloris) Chloris virgata
Carolina jointtail Coelorachis cylindrica
Fall witchgrass Digitaria cognata
American barnyard grass Echinochloa muricata
Canada wildrye Elymus canadensis
Virginia wildrye Elymus virginicus
Gummy lovegrass Eragrostis curtipedicellata
Big-top lovegrass Eragrostis hirsuta
Plains lovegrass Eragrostis intermidia
Spreading lovegrass Eragrostis pectinata
Creeping lovegrass Eragrostis reptans
Poverty droopseed Sporobolus vaginiflorus
White tridens Tridens albescens
Purpletop (redtop, purpletop tridens) Tridens flavus
Longspike tridens Tridens strictus
Eastern gammagrass Tripsacum dactyloides
Prairie trisetum Trisetum interruptum
Browntop signalgrass (Hurrah grass) Urochloa fasciculata
Design Criteria Manuals 216
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Table E-3: Native Plants List – Grasses
Common Name Botanical Name
Broadleaf signalgrass Urochloa platyphylla
Texas panicum (Texas signalgrass) Urochloa texana
Common sixweeksgrass Vulpia octoflora
Design Criteria Manuals 217
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Table E-4: Native Plants List – Herbaceous Wetland
Common Name Botanical Name
Ear-leaf ammannia Ammannia auriculata
Purple ammannia (Toothcup) Ammannia coccinea
Water-hyssop Bacopa monnieri
Disk water-hyssop Bacopa rotundifolia
Texas bergia (waterwort) Bergia texana
Caric sedge (Benjamin's sedge) Carex bushii
Davis' Caric sedge Carex davisii
Heavy-fruit caric sedge Carex gravida
Few-flower caric sedge Carex hyalina
Foxtail caric sedge Carex vulpinoidea
Taper-leaf flat sedge Cyperus acuminatus
Yellow flat sedge Cyperus flavescnes
Slender flat sedge Cyperus lupulinus
Fragrant flat sedge Cyperus odoratus
Bent-awn flat sedge Cyperus reflexus
One-flower flat sedge Cyperus retroflexus
Sedge Cyperus setigerus
Burhead (Erect burhead) Echinodorus berteroi
Creeping burhead Echinodorus cordifolius
Needle spikerush Eleocharis acicularis
Spikerush Eleocharis geniculata
Spikerush Eleocharis monteicensis
Large-spike spikerush Eleocharis palustris
Dwarf spikerush Eleocharis parvula
Square-stem spikerush Eleocharis quadrangulata
Horsetail (Scouring-rush) Equisetum hyemale
Fimbristylis Fimbristylis puberula
Umbrella sedge Fuirena simplex
Bladderpod (Bagpod) Glottidium vesicarium
Blue mud plantain Heteranthera limosa
Water-pennywort Hydrocotyle umbellata
Dudley's rush Juncus dudleyi
Common rush (Soft rush) Juncus effusus
Ring-seed rush Juncus filipendulus
Inland rush Juncus interior
Grassleaf rush Juncus marginatus
Torrey's rush Juncus torreyi
Water willow Justicia americana
Slender-leaf flat sedge Kyllinga pumila
Design Criteria Manuals 218
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Table E-4: Native Plants List – Herbaceous Wetland
Common Name Botanical Name
Frogfruit (Lance-leaf frogfruit) Lippia lanceolata
Frogfruit (Turkey tangle) Lippia nodiflora
Seedbox (Rattlebox) Ludwigia alternifolia
Primrose-willow Ludwigia decurrens
Creeping seedbox (Torrey's seedbox) Ludwigia glandulosa
Water primrose Ludwigia prploides
Floating water primrose (Creeping primrose) Ludwigia repens
Water horehound (American bugleweed) Lycopus americanus
Lance-leaf loosestrife Lythrum alatum
California loosestrife Lythrum californicum
Prostrate water-hyssop Mecardonia procumbens
Lax hornpod Mitreola petiolata
Water pepper (Swamp smartweed) Polygonum hydropiperoides
Pink smartweed Polygonum pensylvanicum
Water smartweed Polygonum punctatum
Pleat-leaf knotweed Polygonum tenue
Pickerelweed Pontederia cordata
Star-rush white-top sedge (Umbrella grass) Rhynchospora colorata
Toothcup Rotala remosior
Common arrowhead (Duck potato, Wapato) Sagittaria latifolia
Delta arrowhead Sagittaria platyphylla
Lizard's tail Saururus cernuus
Giant bulrush Schoenoplectus californicus
Three-square bulrush (American bulrush) Schoenoplectus pungens
Soft-stem bulrush (Great bulrush) Schoenoplectus tabernaemontani
Rattlebush Sesbania drummondii
Southern cattail Typha domingensis
Common cattail Typha latifolia
Design Criteria Manuals 219
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Table E-5: Native Plants List – Aquatic Plants
Common Name Botanical Name
Larger waterwort Callitriche heterophylla
Coontail Ceratophyllum demersum
Water stargrass Heteranthera dubia
Umbrella water-pennywort Hydrocotyle umbellata
Lesser duckweed Lemna aequinoctialis
Southern naiad Najas guadalupensis
Lotus Nelumbo lutea
Spatterdock (Cow lily, Yellow pond lily) Nuphar advena
White water-lily Nymphaea odorata
Water-thread pondweed Potamogeton diversifolia
Long-leaf pondweed Potamogeton nodosus
Baby pondweed Potamogeton pusillus
Sago pondweed Stuckenia pectinatus
Cone-spur bladderwort Utricularia gibba
Wild celery (Eel grass) Vallisneria americana
Common poolmat (horned pondweed) Zannichelia palustrus
Design Criteria Manuals 220
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Table E-6: Native Plants List – Ferns
Common Name Botanical Name
Engelmann's Adder's tongue Ophioglossum engelmannii
Adder's tongue Ophioglossum vulgatum
Purple cliff-brake Pellaea atropurpurea
Common woodsia Woodsia obtusa
Design Criteria Manuals 221
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Table E-7: Native Plants List – Cacti
Common Name Botanical Name
Pinapple cactus Coryphantha sulcata
Pincushion cactus Coryphantha vivipara
Plains nipple cactus Escobaria missouriensis
Eastern prickly-pear Opuntia humifusa
Plains prickly-pear Opuntia macrorhiza
Brown-spine prickly-pear Opuntia phaeacantha var. major
Green-flower cholla (Jumping cactus) Opuntia tunicata
Design Criteria Manuals 222
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Table E-8: Native Plants List – Forbs (Wildflowers)
Common Name Botanical Name
Prairie acacia Acacia angustissima
Hop hornbeam Acalypha ostryifolia
Virginia copperleaf Acalypha virginica
Western yarrow Achillea millefolium
Wild onion (Meadow garlic) Allium canadense
Prairie onion Allium drummondii
Blue star (Texas slimpod) Amsonia ciliata
Ble star (Willow slimpod) Amsonia tabernaemontana
Blue funnel lily Androstephium coeruleum
Tenpetal anemone Anemone berlandieri
Carolina anemone Anemone caroliniana
Western rock-jasmine Anrdosac occidentalis
Pussytoes anemone Antennaria parlinii
Arkansas lazy daisy Aphanostpehus skirrhobasis
Prairie dogbane (Indian-hemp) Apocynum cannabinum
Green-dragon (Jack-in-the-pulpit) Arisaema dracontium
Indian plantain Arnoglossum plantagineum (Cacalia plantaginea)
Antelope-horns (trailing milkweed) Asclepias asperula
Butterfly milkweed Asclepias tuberosa
Green-flower milkweed Asclepias viridiflora
Green milkweed Asclepias viridis
Drummond's aster Aster drummondii
Heath aster Aster ericoides
Aromatic aster Aster oblongifolius
Late purple aster Aster patens var. gracilis
Silky aster Aster pratensis
Saltmarsh aster Aster subulatus
Bent-pod milk-vetch Astragalus distortus
Slim-pod milk-vetch Astragalus leptocarpus
Lotus milk-vetch Astragalus lotiflorus
Western daisy Astranthium intefrifolium
Plains wild indigo Baptisia bracteata
Green wild indigo Baptisia sphaerocarpa
Texas green-eyes Berlandiera betonicifolia (B. texana)
Prairie Bishop's weed Biflora americana
Scarlet spiderling Boerhavia diffusa
Erect spiderling Boerhavia erecta
Plains kuhnia (False boneset) Brickellia eupatorioides var. corymbulosa
Plains winecup (Plains poppy-mallow) Callirhoe alcaeoides
Design Criteria Manuals 223
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Table E-8: Native Plants List – Forbs (Wildflowers)
Common Name Botanical Name
Winecup (Purple poppy-mallow) Callirhoe involucrata
Palmleaf poppy-mallow (Finger poppy-
mallow) Callirhoe pedata (C. digitata)
Sundrops (Squarebud day primrose) Calylophus berlandieri
Yellow sundrops (yellow eveving-primrose) Calylophus serrulatus
Horseherb (Prostrate lawnflower) Calyptocarpus vialis
Wild hyacinth Camassia scilloides
Indian paintbrush Castilleja indivisa
Redroot (Jersey tea) Ceanothus herbaceus
Basketflower Centaurea americana
Mountain pink Centaurium beyrichii
Lady Bird's centaury Centaurium texense
Short-stalked chickweed Cerastium brachypodum
Nodding chickweed Cerastium nutans
Wild cherry Chaerophyllum tainturieri
Common least daily Chaetopappa asteroides
Partridge pea Chameachrista fasciculata (Cassia fasciculata)
Sensitive pea Chameachrista nicitans (Cassia nictitans)
Pit-seed goosefoot Chenopodium berlandieri
Thick-leaf goosefoot Chenopodium pratericola
Soft golden aster (Camphorweed) Chrysopsis pilosa
Tall thistle Cirsium altissimum
Bull thistle Cirsium horridulum
Texas thistle Cirsium texanum
Violet collinsia Collinsia voilacea
Erect dayflower Commelina erecta
Texas bindweed Convolvulus equitans
Horseweed Conyza canadensis
Rain-lily Cooperia drummondii
Lance Coreopsis Coreopsis lanceolata
Plains coreopsis Coreopsis tinctoria
Rock coreopsis Coreopsis wrightii
Mealy fumewort Corydalis crystallina
Scratch daisy Croptilon hookerianum
Woolly croton Croton capitatus
Tropic croton Croton glandulosus
One-seeded croton Croton monanthogynous
Texas croton Croton texensis
Buffalo gourd Cucubita foetidissima
Texas Gourd Cucurbita texana
Design Criteria Manuals 224
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Table E-8: Native Plants List – Forbs (Wildflowers)
Common Name Botanical Name
Winged pigweed Cycloloma atriplicifolium
Showy prairie clover Dalae compacta
Golden dalea Dalea aurea
White prairie clover Dalea candida var candida
Bigtop dalea Dalea enneandra
Round-head dalea (White prairie clover) Dalea multiflora
Angels Trumpet (Indian apple) Datura wrightii
Rattlesnake-weed Daucus pusillus
Prairie larkspur Delphinium carolinianum var. virescens
Tansy mustard Descurainia pinnata
Illinois bundleflower Desmanthus illinoensis
Prairie bundleflower Desmanthus leptolobus
Panicled tick-clover Desmodium paniculatum
Sessile tick-clover Desmodium sessilifolium
Tweedy's tick-clover Desmodium tweedyi
Pony foot Dichondra carolinensis
Woolly cotton-flower Dimorphocarpa wislizenii
Rough buttonweed Diodia teres
Low silverbush (Low wild mercury) Ditaxis humilis
Shooting star Dodecatheon meadia
Wedge-leaf draba (Whitlow-wort) Draba cuneifolia
Broad-pod draba Draba platycarpa
Carolina draba Draba reptans
Clasping coneflower Dracopis amplexicaulis
Snake Herb Dyschoriste linearis
Blacksamson Echinacea angustifolia
Purple coneflower Echinacea atrorubens
Yarva de tajo (Pieplant) Eclipta prostrata
Englemann daisy Englemannia peristenia (E. pinnatifida)
Basin fleabane Erigeron geiseri
Philadelphia fleabane Erigeron philadelphicus
Annual wild buckwheat Eriogonum annuum
Longleaf wild buckwheat Eriogonum longifolium
Heart-sepal wild buckwheat Eriogonum multiflorum
Prairie fleabane Eriogonum strigosus
Texas stork's bill Erodium texanum
Brushy eryngo Eryngium diffusum
Hooker's enyngo Eryngium hookeri
Leavenworth eryngo Eryngium leavenworthii
Design Criteria Manuals 225
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Table E-8: Native Plants List – Forbs (Wildflowers)
Common Name Botanical Name
Rattlesnake master (Button snakeroot) Eryngium yuccifolium
Western wallflower Erysimum capitatum
Tall thoroughwort Eupatorium altissimum
Blue mist flower Eupatorium coelestinum
Late-flowering boneset Eupatorium serotinum
Snow-on-the-prairie Euphorbia bicolor
Fire-on-the-mountain Euphorbia cyanthophora
Tootherd spurge Euphorbia dentata
Snow-on-the-mountain Euphorbia marginata
Weak spurge Euphorbia tetrapoda
Texas spreadwing Eurytaenia texana
Bluebells Eustoma russellianum (E. grandiflorum)
Big-head pygmycudweed Evax prolifera
Spring pygmycudweed Evax verna
Shaggy dwarf morning-glory Evolvulus nuttallianus
Silver dwarf morning-glory Evolvulus sericeus
Florida snake cotton Froelichia floridana
Prairie gaillardia (Lanceleaf gaillardia) Gaillardia aestivalis
Indian blanket Gaillardia pulchella
Fragrant gaillardia Gaillardia sauvis
Woods bedstraw (Wild licorice) Galium circaezans
Hairy bedstraw Galium pilosum
Plains gaura Gaura brachycarpa
Sweet gaura (Beeblossom) Gaura drummondii
Velvetweed (Lizard-tail gaura) Gaura parviflora
Wavy-leaf gaura (Wavyleaf beeblossom) Gaura sinuata
Wild honeysuckle Gaura suffulta
Crane's bill (Carolina geranium) Geranium carolinianum
White avens Geum canadense
Dakota vervain Glandularia bipinnatifida (Verbena bipinnatifida)
Rose vervain Glandularia canadensis (Verbena canadensis)
Bladderpod (Bagpod) Glottidium vesicarium
Lonestar gumweed (Little-head gumweed) Grindelia adenodonta
Narrow-leaf gumweed Grindelia lanceolata
Prairie bluets Hedyotis nigricans
Common sunflower Helianthus annuus
Texas blueweed (Blue-weed sunflower) Helianthus cilaris
Maximilian Sunflower Helianthus maximiliani
India heliotrope (turnsole) Heliotropium indicum
Design Criteria Manuals 226
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Table E-8: Native Plants List – Forbs (Wildflowers)
Common Name Botanical Name
Pasture heliotrope Heliotropium tenellum
Bladdermallow (Net-Vein herissantia) Herissantia crispa
Gray golden-aster Heterotheca canescens
Camphorweed Heterotheca subaxillaris
Hawkweed Hieracium gronovii
Nodding green violet Hybanthus verticillatus
Carolina wooly-white (Old-plainsman) Hymenopappus acabiosaeus
Old-plainsman (Woolly-white) Hymenopappus artemisifolius
Spotted St. John's wort Hypericum punctatum
Scarlet pea Indigofera miniata
Standing cypress Ipomopsis rubra
Sumpweed (Marsh-elder) Iva annua
Warty calrop Kallstroemia parviflora
Trailing ratany Krameria lanceolata
Virginia dwarfdandelion Krigia virginica
Wright's dwarfdandelion Krigia wrightii
Wild lettuce Lactuca canadensis
Western wild lettuce Lactuca ludoviciana
Narrow-leaf pinweed Lechea tenuifolia
Virginia pepperweed Lepidium virginicum
Hairy bush-clover Lespedeza hirta
Trailing bush-clover Lespedeza procumbens
Tall bush-clover Lespedeza stuevei
Slender lepedeza Lespedeza virginicum
White bladderpod Lesquerella gracilis
Narrow-leaf conobea Leucospora multifida
Tall gayfeather (Tall blazing star) Liatris aspera
Pink-scale gayfeather (Handsome blazing
star) Liatris elegans
Narrow-leaf gayfeather Liatris mucronata
Prairie blazing star (Kansas gayfeather) Liatris pynchostachya
Smooth gayfeather (Scaly blazing star) Liatris squarrosa var. glabrata
Arkansas dogshade Limnosciadium pinnatum
False pimpernel Lindernia dubia
Texas yellow star Lindheimera taxana
Small meadow flax Linum pratense
Stiffstem flax Linum rigidum
Puccoon (Carolina gromwell) Lithospermum caroliniense
Narrowleaf gromwell (Narrowleaf puccoon) Lithospermum incisum
Cardinal flower Lobelia cardinalis
Design Criteria Manuals 227
Published: January 2026 Go to Table of Contents
Table E-8: Native Plants List – Forbs (Wildflowers)
Common Name Botanical Name
Carrot-leaf lomatium Lomatium foeniculaceum
Deervetch (Prairie trefoil) Lotus purshianus (L. unifoliolatus)
Texas bluebonnet Lupinus texensis
Texas skeleton plant Lygodesmia texana
Turks Cap (Wax mallow) Malvaviscus arboreus v. drummondii
Barbara's buttons (Puffballs) Marshallia caespitosa
Creeping cucumber Melothria pendula
Stickleaf (Chickenthief) Mentzelia oilgosperma
White four-o'clock Mirabilis albida
Giant four-o'clock Mirabilis gigantea
Narrow-leaf four-o'clock Mirabilis linearis
Wild four-o'clock Mirabilis nyctaginea
Carolina bristlemallow Modiola caroliniana
Lemon mint (Lemon beebalm) Monarda citriodora
Basil beebalm Monarda clinopodioides
Wild bergamont Monarda fistulosa
Spotted beebalm Monarda punctata
Poverty-weed Monolepis nuttalliana
Spring forget-me-not Myosotis macrosperma
Southern forget-me-not Myosotis verna
tiny mousetail Myosurus minimus
Prairie celestial Nemastylis geminiflora
Yellow puff Neptunia lutea
Crow poison (False garlic) Nothoscordum bivalve
Texas toad-flax Nuttallanthus texanus
Scarlet muskflower Nyctaginia capitata
Cutleaf evening primrose Oenothera laciniata
Four-point evening primrose Oenothera rhombipetala
Spack evening primrose Oenothera spachiana
Showy evening primrose Oenothera speciosa
Stemless evening primrose Oenothera triloba
Soft-hair marbleseed Onosmodium bejariense
Aniseroot Osmorhiza longistylis
Common yellow oxalis Oxalis stricta
Violet woodsorrel Oxalis vioacea
Prairie groundsel Packera plattensis (Senecio plattensis)
Small palafoxia Palafoxia callosa
Rose palafoxia Palafoxia rosea
Passionflower Passiflora incarnata
Design Criteria Manuals 228
Published: January 2026 Go to Table of Contents
Table E-8: Native Plants List – Forbs (Wildflowers)
Common Name Botanical Name
Tall-bread scurf-pea Pediomelum cuspidata (Psoralea cuspidata)
Rock scurf-pea Pediomelum reverchonii (Psoralea reverchonii)
Round-leaf scurf-pea Pediomelum rhombifolium
Foxglove Penstemon cobaea
Beardtongue Penstemon laxiflorus
Blue curls Phacelia congesta
Annual phlox (Pride-of-Texas) Phlox drummondii var. mcallisterii
Prairie Phlox Phlox pilosa
Drummond's leaf-flower Phyllanthus abnormis
Knotweed leaf-slower Phyllanthus polygonoides
Cut-leaf ground-cherry Physalis angulata
Beach ground-cherry Physalis cinerascens
Downy groundcherry (Husk tomato) Physalis pubescens
Finger flase dragonhead Physostegia digitalis
Beautiful false dragonhead Physostegia pulchella
Obedient Plant Physostegia virginiana var. praemorse
Pokeweed Phytolacca americana
Bracted plantain (Bottlebrush plantain) Plantago aristata
Prairie plantain (Slender plantain) Plantago elongata
Slender plantago (Slim-spike plantago) Plantago heterophylla
Bristle-bracted plantain Plantago patagonica
Red-seed plantain (Tallow-weed) Plantago rhodosperma
Pale-seed plantain Plantago virginica
Purple pluchea (Marsh fleabane) Pluchea odorata
Clammyweed Polansia dodecandra
White milkwort Polygala alba
Pink milkwort (Procession flower) Polygala incarnata
Pleat-leaf knotweed Polygonum tenue
Juniper-leaf Polypremum procumbens
Prairie parsley Polytaenia nuttallii
Common selfheaf (Heal-all) Prunella vulgaris var. lanceolata
Edible scurf-pea Psoralea hypogaeum var. subulatum
Wild alfalfa (Slim-leaf scurf-pea) Psoralea tenuiflora
Mock bishop's weed Ptilimnium nuttallii
False dandelion (Carolina desert-chickory) Pyrrhopappus carolinianus
Texas dandelion (Smallflower desert-
chickory) Pyrrhopappus pauciflorus
Mexican hat (Upright prairie coneflower) Ratibida columnifera
Pigeonberry (Rougeplant) Rivina humilis
Blackeyed Susan Rudbeckia hirta
Design Criteria Manuals 229
Published: January 2026 Go to Table of Contents
Table E-8: Native Plants List – Forbs (Wildflowers)
Common Name Botanical Name
Low ruellia Ruellia humilis
Pale dock Rumex altissimus
Heart-wing sorrel Rumex hastatulus
Meadow pink Sabatia campestris
Buckley's sabatia Sabatia formosa
Trailing pearlwort Sagina decumbens
Blue sage Salvia azurea
Tropical sage Salvia coccinea
Engelmann's sage Salvia engelmannii
Mealycup sage Salvia farinacea
Texas sage Salvia texana
Thin-leaf brookweed Samolus valerandi
Black snakeroot Sanicula canadensis
Catclaw sensitive briar Schrankia nuttallii (Mimosa nutallii)
Roemer sensitive briar Schrankia roemeriana (Mimosa roemeriana)
Small scullcap Scutellaria parvula
Wright's skullcap Scutellaria wrightii
Yellow stonecrop Sedum nuttallianum
Texas groundsel Senecio ampullaceus
Cofee-bean Sesbania herbacea (S. macrocarpa)
Rock cress Sibara virginica
Bur cucumber Sicyos angulatus
Spreading fanpetal Sida abutifolia
Prickly fanpetals Sida spinosa
Sleepy catchfly Silene antirrhina
Widow's frill Silene stellata
Compassplant Silphium laciniatum
Sword-leaf blue-eyed grass Sisyrinchium chilense
Dotted blue-eyed grass Sisyrinchium pruinosum (S. langloisii)
American nightshade Solanum ptychenthum (Solanum americanum)
Common goldenrod Solidago canadensis
Tall goldenrod Solidago gigantea
Stiff goldenrod Solidago rigida
Elm-leaf goldenrod Solidago ulmifolia
Forked scaleseed Spermolepis divaricata
beggar's-lice (Bristly scaleseed) Spermolepis echinata
Spreading scaleseed Spermolepis inermis
Slender ladies' tresses Spiranthes lacera
Mousesear Stachys crenata
Design Criteria Manuals 230
Published: January 2026 Go to Table of Contents
Table E-8: Native Plants List – Forbs (Wildflowers)
Common Name Botanical Name
False gaura Stenosiphon linifolius
Smooth jewelflower (Smooth twistflower) Streptanthus hyacinthoides
Trailing wild bean Strophostyles helvola
Smooth-seed wild bean Strophostyles leiosperma
Sunbright (Prairie flameflower) Talinum parviflorum
Goat's rue (Virginia tephrosia) Tephrosia virginiana
Sawtooth nerveray Tetragonotheca ludoviciana
Fineleaf four-nerve daisy Tetraneuris linearifolia (Hymenoxys linearifolia)
Wood sage Teucrium canadense
Greenthread Thelesperma filifolium
Small Bristle-leaf (Tiny Tim) Thymophylla tenuiloba
Ohis spiderwort Tradescantia ohioensis
Tharp's spiderwort Tradescantia tharpii
Peanut clover Trifolium polymorphum
Venus' looking glass Triodanis holzingeri
Slender-leaved Venus looking-glass Triodanis leptocarpa
Hen and Chickens Triodanis perfoliata
Beaked cornsalad Valerianella radiata
Wood's cornsalad Valerianella woodsiana
Bracted vervain Verbana bractaeta
Texas vervain Verbena halei
Hoary vervain Verbena stricta
White vervain Verbena urticifolia
Gulf vervain (Course vervain) Verbena xutha
Cowpen daisy (Golden crownbeard) Verbesina encelioides
White Crownbeard (Frostweed, Iceplant) Verbesina virginica
Western ironweed Vernonia baldwinii
Purslane speedwell (Neckweed) Veronica peregrina
Blue violet Viola palmata
Common blue violet Viola sororia
Carolina violet Viola villosa
Prairie brazoria Warnockia scutellarioides
Orange zexmenia Wedelia texana (Zexmenia hispida)
Texas sleepy daisy Xanthisma texanum