DERR-2024-009851

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Enbridge Gas
1140 West 200 South
Salt Lake City, Utah 84104
United States
VIA EMAIL

August 13, 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 –
2024 North Shop Paving and Concrete Pad for Sign Completion

Dear Ms. Robinson:

Questar Gas Company (Questar) is submitting this letter as final notice of completion for two
projects occurring within the boundaries of the environmental covenant associated with Questar’s
Salt Lake Operations Center (Figure 1). Project descriptions and work summaries are provided
herein. Please note that effective June 1st, 2024 Enbridge, Inc. purchased Questar from Dominion
Energy. As a result, Questar Gas Company is now doing business as Enbridge Gas Utah (EGU).

On April 16, 2024, EGU provided a letter notification to DERR of its intent to install a concrete
pad for a sign; DERR provided approval on April 17, 2024. The ground disturbance for the
concrete pad was 4-feet by 1.5-feet and approximately 6-inches deep and was completed July 11,
2024. EGU personnel did not monitor the ground disturbance activities; however, based on
multiple previous excavations in this area to greater depths, no impacted soil was expected.
Discussions with the contractor following the installation confirmed no visual or olfactory
indicators of impacted soil were observed.

On May 10, 2024, EGU provided a letter notification to DERR regarding the need to complete a
paving project on the northeast corner of the property; DERR approval was received on May 13,
2024. The ground disturbance activities for the paving project were on conducted on July 22, 2024.
The area that was to be paved was graded, where approximately 3-4 inches of material was
removed. Following the removal of soil, approximately 4-6 inches of an import road base material
was placed and compacted before the area was paved with asphalt. EGU personnel monitored the
ground disturbing activities for visual or olfactory indicators of coal gasification residuals, as well
as for total organic volatiles (TOV) using a photoionization detector (PID). Figure 2 identifies
where the sign concrete pad was installed and the area that was paved. No suspected impacted
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materials were encountered.

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, Environmental

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Figure 1 – Questar Gas Co. Salt Lake Operations Center Overview

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Figure 2 – Concrete Pad for Sign Location and Paving Project Location