DERR-2024-004369

195 North 1950 West
Mailing Address: P.O. Box 144840 Salt Lake City, UT 84114-4840
Telephone [phone] ) 359-8853 [phone]
www.deq.utah.gov
Printed on 100% recycled paper
State of Utah

SPENCER J. COX
Governor

DEIDRE HENDERSON
Lieutenant Governor
Department of
Environmental Quality

Kimberly D. Shelley
Executive Director

DIVISION OF ENVIRONMENTAL
RESPONSE AND REMEDIATION

Brent H. Everett
Director
ERRC-028-24

February 22, 2024

Kristopher Benson
Senior Environmental Compliance Coordinator
Dominion Energy Services, Inc.
120 Tredegar Street
Richmond, Virginia 23219

RE: Response to Comments on Semi-Annual Sampling: October 2023 Monitoring Event
Questar Gas Salt Lake Operations Center

Dear Mr. Benson:

The Utah Department of Environmental Quality, Division of Environmental Response and
Remediation (DERR) has reviewed the Semi-Annual Sampling: October 2023 Monitoring Event
following the response to comments received on January 26, 2024. The DERR has no additional
comments and concurs with finalizing the document. However, the DERR suggests confirming with
the contracted laboratory that method detection limits are below the Maximum Contaminant Levels
for all analytes prior to future sampling events.

If you have any questions, please contact me at [phone].

Sincerely,

Kelsey Robinson, Project Manager
Division of Environmental Response and Remediation

KR/lg

Dominion Energy Services, Inc.
1140 W 200
Salt Lake City, UT, 84104
DominionEnergy.com
BY ELECTRONIC MAIL
Utah Department of Environmental Quality
Division of Environmental Response and Remediation
195 North 1950 West
Salt Lake City, UT, 84114

RE: Questar Gas Company
Response to Comments on October 2023 Semi-Annual Sampling Report
Salt Lake Operations Center
Ms. Robinson,

Questar Gas Company, dba Dominion Energy Utah (Questar), is providing this response
to the comments issued by the Utah Department of Environmental Quality, Division of
Environmental Response and Remediation (DERR) on January 3, 2024 regarding the
October 2023 semi-annual groundwater sampling report for Questar’s Salt Lake City
Operations Center. A revised report is attached incorporating updates specifically
addressed by DERR. Additional discussion is provided below.

Comment 1: Page 7, Section 2. Sampling Results, Table 1 Analytical Methods Used:
This table indicates that USEPA Method 8260 B is to be used for volatile organic
compounds (VOCs) and that USEPA Method 8070C is to be used for semi-volatile
organic compounds (SVOCs). However, the analytical data report from Chemtech-Ford
Laboratories shows that VOCs were analyzed per EPA Method 8260D/5030B and that
SVOCs were analyzed per EPA Method 8270E/3511. Please confirm if the method that
was used by the laboratory is the appropriate method for this site and update the table
accordingly.

Response:Chemtech-Ford Laboratories has confirmed that EPA Method 8260D/5030B
and EPA Method 8270E/3511 are appropriate analytical methods to analyze for VOCs
and SVOCs and are the most current iterations of the methodology. Table 1 has been
updated to reflect the specific analytical methods used.

Comment 2: Page 7, Section 2. Sampling Results, Paragraph 2, Sentence 1: This
sentence indicates field readings that were conducted during sampling. However, there is
Questar Gas Company Response to DERR Comments

Page 2

no mention of turbidity being measured. Given that turbidity was measured in each well
prior to sampling (as shown on well development/purge forms from Appendix B), the
DERR recommends including this within this section of the report.
Response:Section 2 of the report has been revised accordingly.
3. Pages 7 and 8, Section 2. Sampling Results: Table 2-4 indicates that all analytes for
VOCs and SVOCs were below reported detection limits. Please confirm that the minimum
reporting limits that are listed in the laboratory data set are also below the USEPA
Maximum Contaminant Levels (MCLs).
Response:Minimum reporting limits for the following analytes were above USEPA MCLs
for the October 2023 sample set: atrazine, benzo-a-pyrene, 1,2 dibromo-3-chlorpropane,
bis(2-ethylhexyl)phthalate, hexachlorobenzene, pentachlorophenol. Historical analytical
results demonstrate that these compounds, with the exception of atrazine, are not present
at the site in concentrations greater than USEPA MCLs.
Atrazine was first reported in April 2023 when Questar’s contractor began utilizing
Chemtech Ford laboratories to analyze samples collected during semi-annual
groundwater sampling events at the Salt Lake City Operations Center. Neither the April
2023 nor the October 2023 sample sets reported detectable concentrations of atrazine.
Atrazine is an herbicide and, consistent with laboratory results, should not be present at
the Salt Lake City Operations Center.

Minimum reporting limits for all other analytes in the October 2023 sample set are below
applicable USEPA MCLs.

4. Page 9, Section 2.1 Groundwater Level Measurements, Table 5 Piezometer
Groundwater Measurements: SWP 4 listed in this table is shown to have measured
water level depth and elevation. However, on page 16, the Water Level Data Summary in
Appendix B indicates that SWP 4 was ‘paved over’ and shows no recorded
measurements. Please confirm which information is accurate and adjust the table
accordingly.

Response: SWP 4 had been covered by a parking lot repaving project occurring at the
facility and was inaccessible during ERM’s October 24th sampling event. The Piezometer
was uncovered and accessed on November 1st by Questar; water levels were measured
at that time and provided to ERM. Section 2.1 of the report has been updated to
incorporate these details. No damage to SWP 4 occurred.

5. Page 14, Appendix B, Well Development/Purge Form MW-12: Information from this
form indicates that the well was sampled before turbidity stabilized. The DERR
recommends including this condition within the text of the report for this sample.
Additionally, please expand upon any implications this may have as it relates to the
Questar Gas Company Response to DERR Comments
Page 3
integrity of the sample results, given that the turbidity was above 50 nephelometric units
(NTU) and is outside of EPA guidance.
Response:Elevated turbidity measurements are common in Utah in shallow wells
installed in valley fill deposits (fluvial or lacustrine deposits). MW-12 will be assessed to
determine if redeveloping the well will reduce turbidity measurements in the future. All
other parameters had stabilized by the time the sample was collected; reported analytical
results are consistent with historical values and are considered usable. Section 2 of the
report has been updated to describe this condition.
Questar appreciates DERR’s thorough and thoughtful review of this report. If you have
any additional questions please contact Kris Benson at 801-349-6950 or
[e-mail].
Sincerely,
Gordon Murdock
Director, Energy Safety and Environmental
Dominion Energy
Semi-Annual
Sampling Report
October 2023
PREPARED FOR
Questar Gas Company, d/b/a,
Dominion Energy Utah
DATE
January 2024
REFERENCE
0684096
CLIENT: Questar Gas Company, d/b/a, Dominion Energy Utah
PROJECT NO: 0684096 DATE: 17 January 2024
SIGNATURE PAGE
Dominion Energy Semi-Annual Sampling Report
October 2023
0684096
Gregory Wheeler
Partner
Jennifer Hazeldine
Project Manager
Environmental Resources Management, Inc.
250 East 200 South
Floor 16
Salt Lake City, UT 84111
T [phone]
© Copyright 2024 by The ERM International Group Limited and/or its affiliates (‘ERM’). All Rights Reserved.
No part of this work may be reproduced or transmitted in any form or by any means, without prior written permission of ERM.
DOMINION ENERGY SEMI-ANNUAL SAMPLING REPORT
CLIENT: Questar Gas Company, d/b/a, Dominion Energy Utah
PROJECT NO: 0684096 DATE: 17 January 2024 Page i
CONTENTS
1. BACKGROUND 1
1.1 SITE HISTORY 1
1.2 SITE LOCATION 1
2. SAMPLING RESULTS 2
2.1 GROUNDWATER LEVEL MEASUREMENTS 4
APPENDIX A SITE MAP
APPENDIX B GROUNDWATER PURGING AND SAMPLING LOGS AND GROUNDWATER
MEASUREMENTS
APPENDIX C LABORATORY REPORT
APPENDIX D EMAIL COMMUNICATION

LIST OF TABLES
TABLE 1 ANALYTICAL METHODS USED 2
TABLE 2 RESULTS FOR MONITORING WELL OMW-6 3
TABLE 3 RESULTS FOR MONITORING WELL MW-12 3
TABLE 4 RESULTS FOR MONITORING WELL M10 3
TABLE 5 PIEZOMETER GROUNDWATER MEASUREMENTS 4

ACRONYMS AND ABBREVIATIONS
Acronyms Description
°C degrees Celsius
°F degrees Fahrenheit
µs/cm microsiemens per centimeter
ERM Environmental Resources Management, Inc.
Operations
Center
Salt Lake Operations Center
QGC Questar Gas Company, d/b/a, Dominion Energy Utah
SVOC semi-volatile organic compound
USEPA United States Environmental Protection Agency
VOC volatile organic compound
DOMINION ENERGY SEMI-ANNUAL SAMPLING REPORT BACKGROUND
CLIENT: Questar Gas Company, d/b/a, Dominion Energy Utah
PROJECT NO: 0684096 DATE: 17 January 2024 Page 1
1. BACKGROUND
Environmental Resources Management, Inc. (ERM) was commissioned by Questar Gas Company,
d/b/a, Dominion Energy Utah (QGC) to conduct groundwater sampling at the Salt Lake Operations
Center (Operations Center). This report summarizes the activities conducted and the associated
findings from this work.
1.1 SITE HISTORY
The QGC Operations Center is presently located at the site of a former coal gasification facility
that operated between 1908 and 1929. In response to the discovery of organic residues at the
Operations Center site, QGC (formerly the Mountain Fuel Supply Company) initiated a Phase I
Preliminary Investigation in 1985. Results of this investigation indicated the presence of coal
gasification residuals, including polycyclic aromatic hydrocarbons and volatile aromatic compounds
in the soil beneath the Operations Center. Groundwater was found to contain polycyclic aromatic
hydrocarbons, volatile aromatics, and, in some cases, phenol compounds.
A remedy was developed and implemented based on the results of the Phase I and Phase II
investigations, including performing semi-annual groundwater monitoring of upgradient and
downgradient wells.
1.2 SITE LOCATION
The original Operations Center was located west of Salt Lake City's central business district at 100
South Street and 1000 West Street. The site was approximately 5 acres, bounded on the east by
1000 West Street, on the south by the vacated 100 South Street right-of-way, on the west by
1100 West Street, and on the north by the Union Pacific Railroad line. This parcel has
approximately the same boundaries as the property on which the prior owner (Utah Gas and Coke
Company) conducted synthetic gas production by coal gasification prior to 1930. The Operations
Center is currently surrounded by urban land use, with heavy industrial uses to the west;
commercial development to the north; and mixed residential, commercial, and light industrial uses
to the east and south.
QGC also owns or has the right to use:
• A small storage yard north of the Operations Center and the recently abandoned Union Pacific
Railroad line.
• A records storage building, vehicle fueling station, and parking lot to the west across historic
Eleventh West.
• An office building and vehicle maintenance shop to the southwest.
• A parking lot and storage area south of the vacated 100 South Street.
Additionally, there is a network of railroad lines that transverse the area north of the Operations
Center along historic South Temple. The Salt Lake City Corporation storm drain, constructed in
2012, travels in an east-to-west direction and is located between Questar's north fence line and
the small storage yard.
DOMINION ENERGY SEMI-ANNUAL SAMPLING REPORT SAMPLING RESULTS
CLIENT: Questar Gas Company, d/b/a, Dominion Energy Utah
PROJECT NO: 0684096 DATE: 17 January 2024 Page 2
ERM has included a site map as Appendix A for reference.
2. SAMPLING RESULTS
ERM collected groundwater samples from monitoring wells OMW-6, MW-12, and M10 on 24
October 2023. A peristaltic pump with disposable tubing was used to purge approximately 2
gallons of water from each well to collect samples. The disposable tubing was replaced after usage
at each well. ERM used low flow groundwater purging and sampling methodologies to collect
representative samples from the wells’ screened interval.
ERM measured field readings for temperature, pH, conductivity, redox potential, turbidity, and
dissolved oxygen during purging using a YSI Model ProDSS multi-parameter water quality meter,
which was calibrated in accordance with the manufacturer’s specifications. A QGC representative
collected and processed the purged liquids. ERM has provided groundwater purging and sampling
logs as Appendix B.
Chemtech-Ford Laboratory, a Utah-certified environmental laboratory, analyzed the groundwater
samples using appropriate methods for the site.
TABLE 1 ANALYTICAL METHODS USED
Parameter Analytical Method
Volatile organic compounds (VOCs) USEPA Method 8260D/5030B
Semi-volatile organic compounds (SVOCs) USEPA Method 8270E/3511
USEPA = United States Environmental Protection Agency
The groundwater conditions are from the last reading during the low-flow purging for the sample
collection. ERM has included the laboratory analytical report as Appendix C.
DOMINION ENERGY SEMI-ANNUAL SAMPLING REPORT SAMPLING RESULTS
CLIENT: Questar Gas Company, d/b/a, Dominion Energy Utah
PROJECT NO: 0684096 DATE: 17 January 2024 Page 3
TABLE 2 RESULTS FOR MONITORING WELL OMW-6
Parameter Results
VOCs Each analyte was below the laboratory Minimum Reporting Limit.
SVOCs Each analyte was below the laboratory Minimum Reporting Limit.
Appearance Clear, no color
Groundwater Conditions
pH 6.61
Temperature (°C) 17.3
Electrical Conductance (µs/cm) 1,559
°C = degrees Celsius
µs/cm = microsiemens per centimeter
TABLE 3 RESULTS FOR MONITORING WELL MW-12
Parameter Results
VOCs Each analyte was below the laboratory Minimum Reporting Limit.
SVOCs Each analyte was below the laboratory Minimum Reporting Limit.
Groundwater Conditions
Appearance Clear, no color
pH 7.01
Temperature (°C) 17.7
Electrical Conductance (µs/cm) 1,528
TABLE 4 RESULTS FOR MONITORING WELL M10
Parameter Results
VOCs Each analyte was below the laboratory Minimum Reporting Limit.
SVOCs Each analyte was below the laboratory Minimum Reporting Limit.
Groundwater Conditions
Appearance Clear, no color
pH 7.3
Temperature (°C) 16.6
Electrical Conductance (µs/cm) 2,051
DOMINION ENERGY SEMI-ANNUAL SAMPLING REPORT SAMPLING RESULTS
CLIENT: Questar Gas Company, d/b/a, Dominion Energy Utah
PROJECT NO: 0684096 DATE: 17 January 2024 Page 4
2.1 GROUNDWATER LEVEL MEASUREMENTS
ERM measured the water level in each piezometer on 24 October 2023, and the groundwater
elevations appear to have dropped since the previous measurements on 11 April 2023. Further, on
the day of well sampling and water level measurements, we discovered Piezometer SWP-4 had
been paved over during a parking lot re-paving project, and was therefore not accessible. On 1
November 2023, QGC personnel uncovered Piezometer SWP-4 and measured water levels, as well
as water levels in Peizometer SWP-3 for reference. QGC then provided the water level
measurements to ERM via email correspondence. Please refer to Appendix B for current in field
measurements and Appendix D for email communication between ERM and QGC.
TABLE 5 PIEZOMETER GROUNDWATER MEASUREMENTS
Piezometer Reference Elevation
(feet mean sea level)
Static Water Level
(feet below
reference point)
Water Elevation
(feet mean sea
level)
SWP 1 inside wall 4,220.74 7.15 4,213.59
SWP 2 outside wall 4,220.31 6.2 4,214.11
SWP 3 inside wall 4,219.03 5.52 4,213.51
SWP 4 outside wall 4,220.12 0.95 4,219.17
SWP 5 inside wall 4,220.67 7.25 4,213.42
SWP 6 outside wall 4,220.66 8.9 4,211.76
APPENDIX A SITE MAP

APPENDIX B GROUNDWATER PURGING AND SAMPLING
LOGS AND GROUNDWATER
MEASUREMENTS

APPENDIX C LABORATORY REPORT

APPENDIX D EMAIL COMMUNICATION

From:[e-mail]
To:Jennifer Hazeldine
Cc:Nicholas Aldrich; Joshua Pisciotti
Subject:RE: Groundwater Sampling 10/24
Date:Wednesday, November 1, 2023 2:59:43 PM
Attachments:image001.png
WARNING: The sender of this email could not be validated and may not match the person in the "From" field.
EXTERNAL MESSAGE
Hello All, as a follow up from the paved over piezometer (SWP-4) from the sampling event. We were
able to locate and dig out the piezo to get groundwater measurements today. I also got a
measurement from SWP at the same time. Hopefully this helps to be able to complete your report.
Let me know if there are any questions.
SWP-3: 5.52 below top of casing
SWP-4: 0.95 below top of casing
Thanks,
Kristopher Benson
Sr. Environmental Compliance Coordinator
Dominion Energy Services, Inc.
C: 801-349-6950 O: 801-324-3426
From: Jennifer Hazeldine <[e-mail]>
Sent: Thursday, October 19, 2023 4:05 PM
To: Kris Benson (Services - 6) <[e-mail]>
Cc: Nicholas Aldrich <[e-mail]>; Joshua Pisciotti <[e-mail]>
Subject: [EXTERNAL] Groundwater Sampling 10/24
CAUTION! This message was NOT SENT from DOMINION ENERGY
Are you expecting this message to your DE email? Suspicious? Use PhishAlarm to report the message. Open a
browser and type in the name of the trusted website instead of clicking on links. DO NOT click links or open
attachments until you verify with the sender using a known-good phone number. Never provide your DE
password.
Hi Kris,
Just confirming Tuesday, the 24th for groundwater sampling. Nick will arrive onsite, tentatively
about 9:00 AM.

Nick,
Please reach out to Kris at 801-349-6950 prior to heading to the site so he will know when to expect
you as he will need to meet you at the gate.

Thank you,
Jen

Jennifer Hazeldine
Managing Consultant, Scientist
She/Her/Hers

Salt Lake City erm.com
307-575-1139

This e-mail and any attachments may contain proprietary, confidential and/or privileged information. No confidentiality or privilege is
waived or lost by any transmission errors. This communication is intended solely for the intended recipient, and if you are not the
intended recipient, please notify the sender immediately, delete it from your system and do not copy, distribute, disclose, or otherwise act
upon any part of this email communication or its attachments. To find out how the ERM Group manages personal data please review our
Privacy Policy
CONFIDENTIALITY NOTICE: This electronic message contains information which may be
legally confidential and or privileged and does not in any case represent a firm ENERGY
COMMODITY bid or offer relating thereto which binds the sender without an additional
express written confirmation to that effect. The information is intended solely for the
individual or entity named above and access by anyone else is unauthorized. If you are not the
intended recipient, any disclosure, copying, distribution, or use of the contents of this
information is prohibited and may be unlawful. If you have received this electronic
transmission in error, please reply immediately to the sender that you have received the
message in error, and delete it. Thank you.

ERM HAS OVER 160 OFFICES ACROSS THE FOLLOWING
COUNTRIES AND TERRITORIES WORLDWIDE

Argentina
Australia
Belgium
Brazil
Canada
China
Colombia
France
Germany
Ghana
Guyana
Hong Kong
India
Indonesia
Ireland
Italy
Japan
Kazakhstan
Kenya
Malaysia
Mexico
Mozambique
The Netherlands
New Zealand
Peru
Poland
Portugal
Puerto Rico
Romania
Senegal
Singapore
South Africa
South Korea
Spain
Switzerland
Taiwan
Tanzania
Thailand
UAE
UK
US
Vietnam
ERM’s Salt Lake City Office
250 East 200 South
Floor 16
Salt Lake City, UT 84111

T [phone]

www.erm.com