2019-086 Particulate Matter MonitoringDate: April 26, 2019 Report No. 2019-086
INFORMAL STAFF REPORT
TO MAYOR AND CITY COUNCIL
SUBJECT:
Provide information about particulate matter (PM) monitoring results for gas wells Payne #1 and
#2.
EXECUTIVE SUMMARY:
During the April 16 Council public hearing for the Windsor Drive Apartments specific use permit
(S18-0008i) the monitoring results for particulate matter 10 microns and 2.5 microns (PM10 and
PM2.5) for gas wells Payne #1 and #2 obtained on July 20, 2018 were brought up by Mr. Ed Soph
as evidence of PM emissions generated by the nearby gas wells that, in his opinion, would affect
future residents of the proposed development.
City staff have researched the PM monitoring history upwind and downwind for those two wells
as well as the regional conditions for PM in the air during July 2018. The memo from Modern
Geoscience explaining the monitoring results and the context in which those results should be
interpreted that was emailed to the Council last Monday contained a typo on the graphic displayed
on page 2. A corrected memo is attached.
BACKGROUND:
Denton gas well monitoring program is designed with the goal of obtaining accurate,
representative, and defensible monitoring data of the gas wells activity in the city, and it gives
monitoring priority to those well sites closer to protected (or sensitive) land uses. “High” priority
wells are those that are less than 300 feet from sensitive uses, “Moderate” priority sites are those
that are greater than 300 to 1000 feet, and “Low” priority are those that are greater than 1,000
feet. Well sites Payne #1 and #2 are classified as High priority and are monitored twice every
year by Modern Geoscience contractor and twice by the city gas well inspector. Air quality
parameters are measured at the fenceline boundary of the well sites, upwind (ambient air coming
into the well site) and downwind (ambient air leaving the site) with the idea that differences
between the monitoring readings would indicate potential pollutant contributions by the well
sites. Standard monitoring and sampling protocols supported by TCEQ, EPA, and the gas well
industry are used.
The attached memo from Modern Geoscience provides some general information of what PM is
and how is measured, the monitoring history of well sites Payne #1 and #2, the most recent
results for the April 2019 inspections, and clarifications for Mr. Soph statements.
Please let me know if I can provide any additional information.
CONCLUSION:
This IRS has been provided for informational purposes.
ATTACHMENT(S):
April 18, 2019 Modern Geoscience Memorandum
Date: April 26, 2019 Report No. 2019-086
STAFF CONTACT:
Deborah Viera
Assistant Director of Environmental Services
940.349.7162
Deborah.Viera@cityofdenton.com
PROJECT 19003 | APRIL 18, 2019 | PAGE 1
WWW.MODERNGEOSCIENCES.COM
DATE April 18, 2019
PROJECT 19003
ATTN Ms. Deborah Viera, AICP, CFM
Assistant Director
Environmental Services
City of Denton
901A Texas Street
Denton, Texas
SUBJECT Technical Memorandum – Clarification Concerning Particulate Matter Data
Padsite Nos. 13 and 14 (Payne 1 and 2 Padsites)
Denton, Denton County, Texas
Dear Ms. Viera:
Modern Geosciences, LLC (Modern) is pleased to provide this Technical Memorandum to the City of Denton (City)
providing responses to concerns expressed during the April 16, 2019 City Council meeting and consideration of a
Specific Use Permit (SUP) for a mixed-use development near the above-referenced padsites. Since the concerns
centered on a discussion of particulate matter, Modern has included a brief discussion of particulate matter prior
to providing responses to the specific concerns raised.
BACKGROUND ON PARTICULATE MATTER
Particulate Matter (PM) can come in many sizes and shapes and can be made up of hundreds of different
chemicals/minerals. Some are emitted directly from a source, such as construction sites, unpaved roads, fields,
smokestacks or fires; however, most particles form in the atmosphere as a result of complex reactions of
chemicals such as sulfur dioxide and nitrogen oxides, which are common pollutants emitted from power plants,
industrial businesses and automobiles. PM will contain microscopic solids and/or liquid droplets that are so small
that they can be inhaled and potentially cause health problems. According to the United States Environmental
Protection Agency (EPA), particles less than 10 micrometers (microns) in diameter (PM10) pose the greatest risk.
Fine particles smaller than 2.5 microns (PM2.5) are of particular concern as this fraction can travel far distances
and remain in the air for days or weeks and are more readily absorbed into the body. Additionally, PM2.5 is the
most common cause of reduced visibility (haze) in urban areas. A size comparison of PM particles is provided
below.
PROJECT 19003 | APRIL 18, 2019 | PAGE 2
WWW.MODERNGEOSCIENCES.COM
Particulate Matter Size Reference (EPA 2014)
RESPONSE TO COMMENTS
The discussion of concerns during the recent council meeting included the use of data collected by Modern as
part of our ongoing padsite inspection program in support of the City. Specific comments noted in the meeting
by a resident and direct responses to each are included below for informational and clarification purposes.
Comment No. 1: The resident presented to council a “total” Particulate Matter (PM) result of 157
µg/m3 using data from two of Modern’s July 2018 Padsite Inspection reports for Padsite Nos. 13 and
14 (Payne Nos. 1 and 2).
Response: This approach is incorrect in two different ways. The first is that adding two readings from
two different sites would be equivalent to taking the temperature at two different properties and
adding them. For example, it may be 80°F at my home and 88°F at my office, but the combined
temperatures of 168°F does not represent an expected temperature at either location. The second
misunderstanding is that PM10 can be added to PM2.5. In this case, PM10 is by definition already
inclusive of PM2.5 since this measurement is a summation of ALL particulate 10 microns or less.
PROJECT 19003 | APRIL 18, 2019 | PAGE 3
WWW.MODERNGEOSCIENCES.COM
Comment No. 2: The resident presented to council a World Health Organization (WHO) 24-Hour Mean
comparison for PM2.5 and PM10 of 25 µg/m3 and 50 µg/m3.
Response: While the initial screening employed by Modern during our inspections is the observation
of any significant increase above an expected background level or upwind sample, there is a National
Ambient Air Quality Standard (NAAQS) for PM2.5 (35 µg/m3) and PM10 (150 µg/m3) established by the
EPA utilized for our reporting effort. These criteria are presented in our reports with a description of
how the NAAQS is applied and how Modern utilizes PM as an indicator for other potential concerns.
As our data represents a short 10 to 20-minute snapshot in time, it is important to also note that much
more extensive monitoring is required to directly compare against a 24-hour mean. This is also further
described in Modern’s reports.
While the resident is correct to note the individual PM2.5 and PM10 results observed were slightly
elevated from typical ambient levels during the July 2018 monitoring, to attach the generation of the
PM to the padsites in question is not supported by the data since the background levels across the
entire region were elevated (discussion below) and the upwind and downwind monitoring (discussion
below) performed by Modern are nearly identical.
Comment No. 3 The resident continued, noting “these are only two wells out of the 315 located within
the city limits. What are the cumulative effects of the particulate matter emissions of all those other
wells on our air and on our health? How will the particulate matter from Payne Well No. 1 and 2 affect
the health of the residents living in the proposed apartments?”
Response: Modern agrees with the resident’s concern for how PM can affect the health of our
community. To the resident’s point, this is why this parameter is one of many we evaluate during our
padsite inspections. However, in this case, we need to dive a little deeper into the data to understand
why the PM results in question are background in nature and not related to padsite operations at the
time of our inspection.
Evaluating Upwind and Downwind: As part of the City’s inspection program, Modern always includes
an evaluation of both upwind (conditions coming to a site) and downwind (conditions leaving a site)
to aid our understanding of potential contribution from a given padsite. Below are the up and
downwind summaries for both padsites from the event referenced.
PADSITE NO. 13 (PAYNE NO. 2): FROM MODERN’S JULY 2018 PADSITE INSPECTION REPORT
Fenceline Screening Criteria:
Yes No N/A Upwind Observations: Downwind Observations:
PID > 100 ppbv (0.1 ppmv)? <1 ppbv <1 ppbv
Radiation > 20 µR/hr? <15 µR/hr <15 µR/hr
H2S > 80 ppbv (0.08 ppmv)? <5 ppbv <5 ppbv
Methane > 500 ppmv? <5 ppmv <5 ppmv
PM2.5 > 35 µg/m3? 23.27 µg/m3 22.81 µg/m3
PM10 > 150 µg/m3? 63.61 µg/m3 64.45 µg/m3
PROJECT 19003 | APRIL 18, 2019 | PAGE 4
WWW.MODERNGEOSCIENCES.COM
The differences between upwind and downwind conditions for PM2.5 and PM10 are -2% and 1.3%,
respectively and not suggestive of significant contribution from the padsite during the time of our
inspection.
PADSITE NO. 14 (PAYNE NO. 1): FROM MODERN’S JULY 2018 PADSITE INSPECTION REPORT
Fenceline Screening Criteria: Yes No N/A Upwind Observations: Downwind Observations:
PID > 100 ppbv (0.1 ppmv)? <1 ppbv <1 ppbv
Radiation > 20 µR/hr? <15 µR/hr <15 µR/hr
H2S > 80 ppbv (0.08 ppmv)? <5 ppbv <5 ppbv
Methane > 500 ppmv? <5 ppmv <5 ppmv
PM2.5 > 35 µg/m3? 21.17 µg/m3 21.56 µg/m3
PM10 > 150 µg/m3? 47.47 µg/m3 47.77 µg/m3
The differences between upwind and downwind conditions for PM2.5 and PM10 are 1.8% and 0.6%,
respectively and not suggestive of significant contribution from the padsite during the time of our
inspection.
Understanding Background Conditions: Anytime you are evaluating air quality data, it is important to
understand the ambient conditions expected for a given area. In this case, there is a regional
reference that can be utilized in the Texas Commission on Environmental Quality (TCEQ) Continuous
Ambient Monitoring Station (CAMS) No. 56, located at the Denton Airport approximately two (2) miles
southwest of the padsites in question. While CAMS No. 56 does not collect PM10 data, it does collect
hourly PM2.5 data. During the month of July in 2018, PM2.5 ranged up to an hourly average of 39.1
µg/m3. Unfortunately, the TCEQ’s data set does not include July 20th specifically, but a look at the
available data sets confirm this part of the year encountered several days where elevated PM appears
to have been occurring due to conditions unrelated to the padsite.
An additional reference that could be utilized is CAMS No. 60 at Dallas/Hinton which is roughly 34
miles southeast of the padsites in question and also collects hourly PM2.5 data. It should be noted this
CAMS is within a city that does not have oil or gas wells. CAMS No. 60 encountered a maximum PM2.5
of 50.4 µg/m3 in July 2018 and on July 20, 2018 had a maximum of 34.4 µg/m3 and 24-hour average
of 18.5 µg/m3.
Based on the available background data, the observed PM data appears consistent with a regional
range of values seen across Denton and Dallas in July 2018.
Continued Inspection: As noted within our padsite inspection reports, we understand our data
represents only the period of time we are given access to the padsites. However, Denton has
incorporated different inspection requirements within its program based on the padsite’s proximity
to sensitive receptors like the nearby residential area. In this case, Modern’s inspection of Padsite
No. 14 (Payne No. 1) in 2017 led to its priority being elevated from Moderate to High which brings
with it additional fenceline monitoring parameters and a higher frequency of inspection (twice
annually). One way to address the concerns raised by the resident is to continue a risk-based
PROJECT 19003 | APRIL 18, 2019 | PAGE 5
WWW.MODERNGEOSCIENCES.COM
inspection program that ensures the City receives the necessary data needed to make informed
decisions.
As a result, on the continued inspection program, Modern can add some additional information
concerning PM monitoring results at these padsites from other events. Below are the fenceline data
from Modern’s first 2018 inspection event and from our forthcoming April 2019 reports for reference.
PADSITE NO. 13 (PAYNE NO. 2): FROM MODERN’S FEBRUARY 2018 PADSITE INSPECTION REPORT
Fenceline Screening Criteria: Yes No N/A Upwind Observations: Downwind Observations:
PID > 100 ppbv (0.1 ppmv)? <1 ppbv <1 ppbv
Radiation > 20 µR/hr? <15 µR/hr <15 µR/hr
H2S > 80 ppbv (0.08 ppmv)? <5 ppbv <5 ppbv
Methane > 500 ppmv? <5 ppmv <5 ppmv
PM2.5 > 35 µg/m3? 3.22 µg/m3 3.57 µg/m3
PM10 > 150 µg/m3? 13.7 µg/m3 16.5 µg/m3
PADSITE NO. 13 (PAYNE NO. 2): FROM MODERN’S FORTHCOMING APRIL 2019 PADSITE INSPECTION REPORT
Fenceline Screening Criteria:
Yes No N/A Upwind Observations: Downwind Observations:
PID > 100 ppbv (0.1 ppmv)? <1 ppbv <1 ppbv
Radiation > 20 µR/hr? <15 µR/hr <15 µR/hr
H2S > 80 ppbv (0.08 ppmv)? <5 ppbv <5 ppbv
Methane > 500 ppmv? <5 ppmv <5 ppmv
PM2.5 > 35 µg/m3? 6.51 µg/m3 6.54 µg/m3
PM10 > 150 µg/m3? 21.31 µg/m3 19.54 µg/m3
PADSITE NO. 14 (PAYNE NO. 1): FROM MODERN’S FEBRUARY 2018 PADSITE INSPECTION REPORT
Fenceline Screening Criteria: Yes No N/A Upwind Observations: Downwind Observations:
PID > 100 ppbv (0.1 ppmv)? <1 ppbv <1 ppbv
Radiation > 20 µR/hr? <15 µR/hr <15 µR/hr
H2S > 80 ppbv (0.08 ppmv)? <5 ppbv <5 ppbv
Methane > 500 ppmv? <5 ppmv <5 ppmv
As a Moderate padsite, PM was not initially evaluated.
PADSITE NO. 14 (PAYNE NO. 1): FROM MODERN’S FORTHCOMING APRIL 2019 PADSITE INSPECTION REPORT
Fenceline Screening Criteria:
Yes No N/A Upwind Observations: Downwind Observations:
PID > 100 ppbv (0.1 ppmv)? <1 ppbv <1 ppbv
Radiation > 20 µR/hr? <15 µR/hr <15 µR/hr
H2S > 80 ppbv (0.08 ppmv)? <5 ppbv <5 ppbv
Methane > 500 ppmv? <5 ppmv <5 ppmv
PM2.5 > 35 µg/m3? 6.38 µg/m3 6.39 µg/m3
PM10 > 150 µg/m3? 22.09 µg/m3 21.32 µg/m3
PROJECT 19003 | APRIL 18, 2019 | PAGE 6
WWW.MODERNGEOSCIENCES.COM
As recorded in the fenceline data above, the fenceline monitoring recorded during preceding and
following inspections did not encounter elevated readings or conditions suggestive significant
impact to off-site properties was occurring. Modern did observe elevated ambient PM levels during
the July 2018 event, but this was demonstrated to be associated with a regional event and not
padsite operations. However, it is important to note that leaks from separators and aboveground
storage tanks were identified by Modern during our inspection efforts. Following communication
of these action items, each was reportedly addressed by the operator.
It is Modern’s opinion that the optimum approach to minimizing the potential that an oil or gas padsite impact a
neighboring property is to have a comprehensive inspection program that effectively identifies leaking equipment
and/or fenceline concerns early and communicates these to an operator in a manner that results in corrective
action. Better data leads to better decisions.
CLOSING
We appreciate the opportunity to assist the City in a discussion of air quality. If we can help in any other manner
or participate in future meetings, please let us know. Should you have comments or questions concerning this
letter, please contact the undersigned at your convenience.
Respectfully submitted,
Kenneth S. Tramm, PhD, PG, CHMM
SENIOR PROJECT MANAGER
MODERN GEOSCIENCES
TEXAS REGISTERED GEOSCIENCE FIRM 50411
TEXAS REGISTERED ENGINEERING FIRM F-16201
TCEQ RCAS NO. 0000167