2019-119 Robson Ranch Wastewater DiversionDate: June 7, 2019 Report No. 2019-119
INFORMAL STAFF REPORT TO MAYOR AND CITY COUNCIL SUBJECT: During the Wastewater Budget presentation on June 4, 2019, Mayor Pro Tem Hudspeth asked
for additional information concerning diversion of wastewater from the Robson Ranch Water
Reclamation Plant to the Denton wastewater collection system.
BACKGROUND:
The Robson Ranch development wastewater flows are currently treated at the Robson Ranch
Water Reclamation Plant (RRWRP). This plant provides wastewater treatment service only to
the Robson Ranch development, and currently has capacity to treat 375,000 gallons of average
daily flow. To serve the fully developed condition of Robson Ranch the plant will need to have
capacity to treat 1.6 million gallons of average daily flow.
In July 2015, Robson developers, the Denton City Manager, the Assistant City Manager -
Utilities, and wastewater staff met and reached an understanding to explore abandonment of the
RRWRP and pumping all wastewater flows from Robson Ranch to the Denton wastewater
collection system. This approach was considered positive for both the Robson development and
the City. In the future, Denton will need to construct a wastewater treatment plant in the Hickory
Creek sewer basin as the basin population continues to grow. When considering this future need,
it would be impractical and costly to continue to run a small plant in the same sewer basin.
There will be improved economies of scale for capital, operational, and maintenance costs
gained from the future larger treatment facility.
With the above understanding in place, staff worked on a Development Agreement with Robson
developers. As part of this agreement, Denton would secure the necessary offsite easements, and
design and construct the wastewater diversion facilities. Robson would pay $4 million for the
wastewater diversion project. Upon completion of the diversion project, Robson will begin
paying wastewater impact fees and would not be required to further expand the treatment
capacity of the RRWRP. The RRWRP would then be decommissioned and converted into a
pump station. In accordance with the Agreement, homes within Robson Ranch are required to
pay impact fees and Robson Developers will receive an impact fee credit of $1,000 for the first
1,000 homes, for a total of $1,000,000 for funding the wastewater diversion infrastructure.
Denton staff engaged Hillwood (representing Petrus Investment, L.P.) to acquire an easement
that passes through the Hunter Ranch property owned by Petrus Investment, L.P.. Staff worked
with Hillwood on an agreement and easement documents to memorialize the acquisition of the
easement in Hunter Ranch. As part of providing the easement through Hunter Ranch for a
Date: June 7, 2019 Report No. 2019-119
nominal charge of $20, the City agreed to provide Hunter Ranch capacity for at least 800 single
family equivalent in the gravity main that would run through the Hunter Ranch property. Hunter
Ranch will pay impact fees for all connections at the prevailing rate at the time of connection to
the Denton wastewater system.
Summary:
Robson Agreement
Cost Benefit Denton Cost
Wastewater Diversion
Project (Pumping
Option)
$4 Million* Avoid cost of additional plant
expansion and permit
requirements and impact fee
credit.
$0
*estimated cost to complete pumping option
Petrus / Hillwood Agreement
Cost Benefit Denton Cost
Dedication of Easement Land Cost 800 SFE Wastewater Capacity* $20
*Impact fees will be paid
Denton Savings with Wastewater Diversion Project instead of 1.6 MGD plant
Plant option Wastewater Diversion Project Difference
Annual O&M Costs $895,000 $65,000 Annual: $830,000
20 Year O&M Costs $17,900,000 $1,300,000 20yr: $16,600,000
The essence of the agreement for Denton is that the operation and maintenance of a remote
wastewater treatment plant is more expensive than maintaining a pump station in Robson Ranch.
In addition, Robson Ranch will begin paying wastewater impact fees that will help cover the cost
of providing conveyance and treatment costs for the diverted Robson flows. Hunter Ranch is
provided capacity in this system, which will help provide wastewater services as Hunter Ranch
starts. In summary, the agreement provides benefits to all parties involved.
DISCUSSION:
These Wastewater Services Agreements with Hillwood and Robson Ranch were approved by
City Council on March 26, 2019.
ATTACHMENT(S): None
STAFF CONTACT:
Date: June 7, 2019 Report No. 2019-119
Kenneth Banks. General Manager of Utilities (940) 349-7165
Kenneth.Banks@cityofdenton.com