DERR-2025-001635

Rockwell Solutions, Inc., 718 E. Bridger Lane, Elk Ridge, UT 84651 801-361-2930 [e-mail]
1

Rockwell Solutions, Inc.
718 E Bridger Lane
Elk Ridge, UT 84651
[phone]
March 3, 2025

Mark Smith
Triple Stop Chevron
1034 West Gentile Street
Layton, Utah 84041

RE: Groundwater Monitoring (NUB-28)
Triple Stop Chevron, 1034 West Gentile Street, Layton, Utah 84041
Facility ID #3000500; Release NUB

Dear Mr. Smith:

Rockwell Solutions, Inc. submits this work plan and budget to collect groundwater samples at the
above-referenced site. PST Fund payment claims will reference this work plan and specific tasks
itemized below.

INTRODUCTION

On February 14, 2019, Layton City reported petroleum odors in the basement of a home near the
intersection of Gentile and Angel streets. This prompted an investigation initiated by the Utah
Department of Environmental Quality (UDEQ). On February 16, two other homeowners reported
gasoline vapors in their basements. Some of the residents voluntarily left their homes until abatement
actions were initiated. To mitigate vapor intrusion for the several residences, ATC, an environmental
contractor to the Utah Division of Environmental Response and Remediation (DERR), installed vapor
mitigation blower systems at three of the homes in an effort to abate vapor concentrations around the
homes.

After several years of remediation and groundwater monitoring, it appears that no further action will be
required. All dissolved hydrocarbon concentrations collected on January 14, 2025, were below Initial
Screening Levels. The purpose of this work plan is to confirm that hydrocarbon concentrations are
below

SCOPE OF WORK

Groundwater Monitoring
Groundwater samples will be collected from the following twenty-three monitoring wells which have
had detectable concentrations over the last three to four years:

Work Plan NUB-28, Groundwater Monitoring, Triple Stop Chevron, Layton, Utah. 3000500
Rockwell Solutions, Inc., 718 E. Bridger Lane, Elk Ridge, UT 84651 801-361-2930 [e-mail]
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MW-1 MW-13 MW-23 MW-31 MW-41 MW-45
MW-2 MW-18 MW-24 MW-32 MW-42 EW-3
MW-4 MW-19 MW-27 MW-35 MW-43 EW-4
MW-10 MW-21 MW-29 MW-40 MW-44

The groundwater monitoring event will include measuring the depth to groundwater and groundwater
sampling. The sampling will be conducted following standard decontamination, sample collection,
and sample preparation/preservation protocol. Samples will be analyzed for methyl-tert-butyl-ether
(MTBE), benzene, toluene, ethyl benzene, total xylenes, and naphthalene (MBTEXN) and total
petroleum hydrocarbons-gasoline range organics (TPH-GRO) using EPA Method 8260 and TPH-
diesel range organics (TPH-DRO). A Utah Certified Laboratory will conduct all analyses.

Report
A Groundwater Monitoring Report (GMR) will be prepared after the sampling event. The GMR will
include a groundwater elevation contour map and, if present above ISLs, benzene and TPH-GRO
isoconcentration maps.

KEY PERSONNEL

Senior Geologist, Project Manager, Field Technician: David Hansen

COST ESTIMATE

Rockwell Solutions, Inc. estimates the cost to complete the work as described in this work plan is
approximately $6,342.43. A detailed cost breakdown is presented in Table 1. The estimated budget
will require adjustment if the scope of services identified herein is modified.

Thank you for the opportunity to work with you on this project. If you have any questions or concerns,
please feel free to contact me at your convenience.

Sincerely,

David Hansen
Rockwell Solutions, Inc.
Certified UST Consultant CC130

cc: Kevin Beery, DERR
Task 1 - Work Plan Development
LABOR
Hours Title Code Description Rate Total
1 Prepare Work Plan and Budget 760.00$ 760.00$
Total Task 1 760.00$
Task 2 - Groundwater Monitoring Event
LABOR
Hours Title Code Description Rate Total
1 Professional Geologist 102 Senior Management 147.00$ 147.00$
2 Field Scientist 104 field prep and cleanup 101.00$ 202.00$
18 Field Scientist 104 groundwater and travel 101.00$ 1,818.00$
2 Field Technician 106 data compilation 73.00$ 146.00$
4 Project Manager 103 report preparation 118.00$ 472.00$
2 PST Specialist 108 PST Claims 78.00$ 156.00$
1 Clerical 109 Office Mgmt., Project Assistance 62.00$ 62.00$
Subtotal 3,003.00$
OTHER DIRECT COSTS
Item Quantity Unit Rate Total
429 miles 0.67$ 287.43$
water level indicator 2 days 25.00$ 50.00$
sampling supplies 2 days 25.00$ 50.00$
traffic control 2 days 15.00$ 30.00$
bailers 23 each 9.00$ 207.00$
laboratory analysis (8260, 8015) 23 each 85.00$ 1,955.00$
Subtotal 2,579.43$
Total Task 2 5,582.43$
6,342.43$ Total Work Plan
Groundwater Monitoring
Table 1
Triple Stop Chevron, 1034 W Gentile St., Layton, Utah
Budget for Workplan NUB-28
Facility ID# 3000500
mileage to/from site and lab
Rockwell Solutions, Inc.
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