DERR-2024-006415

Underwood Environmental Consulting, Inc.
9475 N. Silver Creek Road  Park City, Utah 84098  Phone [phone]  Fax [phone]

March 22, 2024

Mr. Hong-Lei Tao
Department of Environmental Quality
Division of Environmental Response and Remediation
P.O. Box 144840
Salt Lake City, Utah 84114-4840

Re: Corrective Action Plan Summary Letter
Western Petroleum Inc. / Naples Bulk Plant
1521 South 1500 East, Naples, Utah
Facility ID# 9000171, Release Site KMX

Introduction

This outline presents the Corrective Action Plan (CAP) for Release Site KMX at Western Petroleum,
Inc. in Naples, Utah (project site) (Figure 1). Release site KMX consisted of two underground storage
tanks (USTs) (500-gallon unleaded gasoline and diesel day tanks) located within the containment area of
a former bulk plant housing several above ground storage tanks (ASTs) and two loading racks. The
USTs were removed in 1998 while the ASTs were removed in 2007. The CAP summary Letter has
been prepared on behalf of 1521 South 1500, LLC by Underwood Environmental Consulting, Inc.
(UEC). The general scope for the CAP is to perform limited over-excavation of petroleum hydrocarbon-
impacted soil and transporting that soil to either the Uintah County landfill or the East Carbon
Development Company (ECDC) landfill. The handling of contaminated groundwater pumped from the
excavation, if any, is uncertain at this time, although re-injection back to an open excavation under
permit-by-rule is preferable.

Background

The project site is located in Uintah County, Utah southeast of the intersection of 1500 East and U.S.
highway 40 in Naples, Utah (Figure 1). Adjacent properties include Pilot Thomas Logistics, LLC (Pilot)
to the west and south, a petroleum products storage and wholesale business. Fuel dispensers and
product lines at the Pilot property are located upgradient of the project site and have had documented
petroleum releases to the environment. Based on the timing of tank removals at the project site and
discovery of petroleum release(s) upgradient (2013), it is reasonable to conclude that contamination
from upgradient source(s) has overprinted subsurface contamination from release site KMX. The
existing Western Petroleum warehouse was constructed following excavation of hydrocarbon impacted
soil from the area of the building footprint (2007).

CAP Summary Letter
Western Petroleum Inc. / Naples Bulk Plant, Naples, UT
Facility ID# 9000171, Release Site KMX

Underwood Environmental Consulting, Inc.
2
Environmental sample results and UEC observations during monitoring well installation identified
hydrocarbon impacts to native soil to 12 feet below grade in some locations. The water table is
approximately 9 feet below grade. Free product was observed in monitoring wells during the last
groundwater monitoring event (2018). Hydrocarbon impacts to vadose zone soils are likely at the
former location of the UST-AST containment area.

Following approval of the CAP and completion of the public notification process, a work plan and bids
for the excavation work and site restoration would be procured. Release site KMX was determined
previously to be 100% eligible for cost reimbursement from the Utah Petroleum Storage Tank Fund
(PST Fund).

Corrective Action Alternatives

The following corrective action alternatives were considered (Figure 2):

1) Option 1 – Over-excavation of overburden and hydrocarbon-impacted soil from estimated
release KMX footprint (~9,500 CY), including de-watering, if necessary. Disposal of ~3,000
CY soil at Uintah County Class I landfill or ECDC landfill, with reuse of ~6,000 CY of
material for backfilling. Disposition of groundwater unknown.
2) Option 2 – Limited over-excavation of hydrocarbon-impacted soil from vadose zone at
former UST-AST containment area (~1,200 CY). No groundwater pumping or handling.
Long-term natural attenuation.
3) Option 3 – Permeable bio-wall, or “funnel and gate”, either upgradient of former UST-AST
containment area or downgradient along eastern property line.
4) Option 4 – High vacuum extraction with emphasis on free product recovery.

Selected Corrective Action Rationale

The general consensus for corrective action at the project site favors Option 2 (limited over-excavation
of hydrocarbon impacted soil from vadose zone at the former UST-AST containment area) (Figure 2).
The corrective action selection was based on the following considerations:

1) Upgradient source(s): Hydrocarbon impacts from release KMX in the subsurface are likely
overprinted by hydrocarbon contamination from upgradient source(s).
2) Contaminants of concern: Total petroleum hydrocarbons (TPH) as gasoline and diesel,
benzene, toluene, ethylbenzene, xylenes.
3) Depth to groundwater: Approximately 9 feet below grade (2018).
4) Depth of hydrocarbon impacts: Approximately 4-12 feet below grade at former UST-AST
containment area. Approximately 7-10 feet below grade upgradient and approximately 9-12
feet below grade downgradient.
5) Site lithology: Native soil includes clay, silt, sand, gravel, and cobbles. Cobbles are most
prevalent at approximately 9 feet below grade. Site conditions are generally not favorable
for remedial methodologies, such as SVE, air sparging, dual-phase high vacuum extraction
(option 4), or other.
6) Per Tri-County Health Dept., the Uintah County landfill facility requires soil be “dry” for
acceptance at the facility. Implies no direct load and haul.
CAP Summary Letter
Western Petroleum Inc. / Naples Bulk Plant, Naples, UT
Facility ID# 9000171, Release Site KMX

Underwood Environmental Consulting, Inc.
3
7) Disposition of groundwater pumped from excavation or wells: Considerable uncertainty,
although re-injection of treated groundwater to open excavation preferable.

The following permits and approvals are anticipated to be obtained for this work:

1) DERR work plan approval(s),
2) Tri-County Health Dept. (soil disposal at Uintah Co. landfill), or ECDC waste profile.
3) DWQ permit-by-rule for treated groundwater discharge back to excavation, if necessary.
4) DAQ? Landfarming to dry out soil prior to disposal at Uintah co. landfill.

Upon approval of this CAP Summary Letter, a Public Notice would be prepared for approval and
distribution. A bid document for the remedial work would also be prepared and bids solicited.

Respectfully,
James A. McReel, P.G.
Certified UST Consultant #CC-0044

Attachments: Figure 1 Site Map

cc: Mr. Mark Caldwell, 1521 South 1500 East, LLC
CAP Options
FIGURE 2
Funnel & Gate - Option 3
Proposed Excavation - Option 1
Proposed Excavation - Option 2
Groundwater Flow Direction
(April 28, 2015)
Proposed Excavation Area
Option 1
Funnel & Gate
Option 3
Hi-Vac Extraction
Option 4
Proposed Excavation Area
Option 2
Sanitary Sewer
Telephone Lines
Natural Gas
Water Line
Property Line
Buried Power Line
Buried Propane Line
MW-5
SB-21
MW-9
Destroyed Monitoring Well
(10/7/00)
Release NCE Soil Boring
(January 2014)
UST Closure Samples
(June 1998)
Irrigation Monitoring Well (6/11/14)
Monitoring Well (8/18/11)
MW-2
SS4
WS4
MW-17 Monitoring Well (4/6-7/15)
Monitoring Well (Pangean
Installed 2014)
GW-1
DP-1 Soil Boring (4/7/15)
Soil Boring (Pangean 7/15/14) SB-1
3/19/2024
?
Sewer Manhole
Sewer
Manhole
Western Petroleum Building/
Warehouse
Former Naples
Truck Stop
Canopy
AST’s and Containment
AST’s and
Containment
AST’s and Containment
1500 South
16
2
5

E
a
s
t
Former Warehouse
Quonset Hut
Former Shop
Former StorageFormer Storage
Fo
r
m
e
r

O
f
fi
c
e
Former USTs
(see inset map)
Pond
Fo
r
m
e
r

AS
T
s
a
n
d

C
o
n
t
a
i
n
m
e
n
t
Propane Tank
Former 4,000 Gallon
Used Oil UST
Pilot Logistics Fueling Area
Pilot Logistics Fueling Area
Truck Loading Rack
Approximate Locations
of 2007 Pacific West
Excavations
SB-20
SB-21
SB-22
SB-23
SB-31
SB-24
SB-17
SB-16
SB-15
SB-14
SB-18
SB-25
SB-26
SB-27
MW-12
MW-10
MW-7
MW-9
MW-13
MW-14
MW-15
MW-6
MW-3
MW-2
MW-1
MW-5
MW-11
MW-8
MW-4
MW-16
MW-18
MW-19
MW-20
MW-17
MW-21
DP-1
DP-2
GW-1
GW-2
GW-3
GW-4
GW-5
GW-7
GW-6
GW-8
GW-9
GW-10
SB-1
SS3
WS3
SS4
WS4Product Line Trenches
(to former ASTs)
Communication Line Trench
(to former card reader)
February 2013 - Discovery
of Gasoline Product Line
Failure/Release
Naples Bulk Plant
1521 S. 1500 E.
Naples, UT 84078
Facility ID# 9000171
Release Code: KMX
NORTH
approx. scale in feet
00 35 70 140105
LEGEND
Original Drawing 11” X 17”, Adjust Scale Accordingly