DERR-2024-008339

Dominion Energy Services, Inc.
120 Tredegar Street, Richmond, VA 23219
DominionEnergy.com

VIA EMAIL

May 9, 2024

Kelsey Robinson
Environmental Scientist
Utah Department of Environmental Quality
Division of Environmental Response and Remediation
168 North 1950 West
Salt Lake City, Utah 84116

RE: Environmental Covenant Questar Gas Salt Lake Operations Center –
North Shop Paving Project

Dear Ms. Robinson:

Questar Gas Company (Questar), d/b/a as Dominion Energy Utah (DEU), is providing a
30-day notification to the Division of Environmental Response and Remediation (DERR)
to conduct excavation activities within the Salt Lake Operations Center Environmental
Covenant boundaries. The excavations will take place as part of a paving project. An
overview of the Environmental Covenant boundaries is provided in Figure 1, and planned
ground disturbance areas are shown in Figure 2. Project details are provided herein.

The paving effort will include the paving of an approximately 20-foot wide strip of land
along the north property boundary. This area is being paved in order to limit the amount of
storm water infiltration into groundwater within the slurry wall. For the majority of the
proposed paved area vegetation will be removed with minimal ground disturbance,
approximately 6-inches of road base will be placed and compacted, and 3-inches of asphalt
will then be laid. In order to match the pavement height to the sidewalk to the east,
approximately 1-foot of material will be excavated up to 100 feet west of the eastern
boundary. Following excavation, 6-inces of road base will be placed and compacted, and
3-inches of asphalt will be laid. The entire proposed pavement area is over the top of the
slurry wall, which is anticipated to be at least 18-inches below the surface. Excavations for
paving will not exceed 12-inches and if the slurry wall is encountered during ground
disturbance activities, work will be stopped and alternative installation options will be
determined as to not disturb the slurry wall. The proposed repaving area is shown on Figure
2.

A DEU Environmental Compliance Coordinator (ECC) will lead a Health Hazard Advisory
Kelsey Robinson
May 9, 2024
Page 2 of 4

(HHA) meeting with all involved personnel to review the property’s history and potential
health hazards for the day’s tasks prior to any work requiring ground disturbance. All
project personnel will be required to attend the HHA meeting and verify that they
understand the information provided. The ECC will remain onsite for the duration of the
ground disturbing work to perform continuous environmental monitoring and to ensure the
slurry wall is not encountered. The ECC will visually inspect excavated soils for signs of
contamination (odor, staining, discoloration, indication of free product or residuals) and
conduct atmospheric monitoring with a field-calibrated photoionization detector (PID), as
necessary. If any contaminated soils are encountered, they will be isolated, characterized,
and managed for appropriate off-site disposal.

The ECC will stop work if Action Levels specified in the Environmental, Health, Safety
and Site Management Plan (2.50 parts per million-volt) are exceeded. Work will re-
commence following the implementation of exposure controls and reduction in exposure
to contaminants in the breathing zone to below prescribed Action Levels. Upon completion
of the work, DEU will submit a report to UDEQ to provide information related to any
impacted materials encountered, laboratory analytical results, and waste generation and
disposal.

DEU anticipates that subsurface work will not exceed 12-inches below ground surface.
Excavation activities will be completed by DEU and overseen by a DEU representative as
described above. If encountered, DEU intends to manage impacted soil for off-site
disposal.

If you have any questions or concerns related to this notice, please contact me at 307-371-
0966 or [e-mail].

Sincerely,

Adam Plonsky
Manager, BU Environmental Compliance

Kelsey Robinson
May 9, 2024
Page 3 of 4

Figure 1 – Salt Lake City Operations Center Overview Map

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May 9, 2024
Page 4 of 4

Figure 2 – Proposed Ground Disturbance Area