DERR-2024-009389

Underwood Environmental Consulting, Inc.
1

July 31, 2024

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

Re: Soil Vapor Sampling Plan
Former Calvinco Co. (Intermountain Lock)
3106 South Main Street
South Salt Lake, Utah
Facility ID #4000124, Release Site OBL

Dear Mr. Crim,

Based on previous correspondence, two temporary soil vapor sampling points located outside the building
footprint itself are proposed. One would be placed near MW-5 and the other near MW-7 (Figure 1). Each
sampling point would be emplaced through the 8” thick concrete slab a few feet from the actual monitoring wells.
Vapor pins® would be installed by a qualified drilling subcontractor. Vapor samples would subsequently be
collected from the subsurface using summa cans. Air sampling protocol outlined in the DERR PST
Environmental Media Sampling Handbook (June 1, 2021) would be followed. The vapor samples would be
analyzed using EPA method TO-15 for MTBE, BTEXN, and TPH gas (C5-C12). The vapor pins® would be
removed and the drill holes patched immediately after sampling.

The analytical results of vapor sampling would be compared with June 2015 Utah DERR RBCA commercial
sub-slab guidance, or other pertinent guidance. A brief letter report would be prepared and transmitted to
stakeholders. A rendering of the ground floor of the IML building is attached as Figure 2.

Respectfully,
Underwood Environmental Consulting, Inc.
L. Earl Underwood, P.G.
Sr. Geologist, CC-0018

enclosures: Figure 1 - Soil Vapor Sampling Plan
Figure 2 – Ground Floor Rendering

LEGEND
approx. scale in feet
one inch ~ 30 feet
00 3015
Former Calvinco Co.
(Intermountain Lock)
3106 South Main St.
South Salt Lake, Utah
Facility ID # 4000124
Release Site OBL
NORTH
W
SD
Natural Gas
Water Line
G
W
S
(Utility Locations Approximate)
Power or Unknown
SD Storm Drain
CommunicationsC
P
Sanitary Sewer
U
GG
C
S
U
P
SD
SD
C
W
C C
U
S
S
SD
P
U
U
Ma
i
n

S
t
r
e
e
t
Angelo Avenue
Intermountain Lock Security Supply
Closed-in-Place
Diesel UST
Gr
a
c
e

M
a
r
y

M
a
n
o
r
FIGURE 17/31/2024
MW-2
Monitoring Well
B-1
Soil Boring
Soil Boring (Western Geologic, 2021b)
GP-01
91.17 Groundwater Elev. (ft)
9
1
Groundwater Contour Line
(contour interval = 0.1 ft)
Groundwater
Flow Direction
Soil Vapor Sampling
Plan (July 2024)
B-2
B-1
GP-01
GP-02GP-03
GP-04
GP-05
MW-3 MW-1
MW-2
MW-4 MW-6
MW-5
MW-7
V
V
V
Proposed Soil Vapor Sample Point
LEGEND
approx. scale in feet
one inch ~ 30 feet
00 3015
Former Calvinco Co.
(Intermountain Lock)
3106 South Main St.
South Salt Lake, Utah
Facility ID # 4000124
Release Site OBL
NORTH
W
SD
Natural Gas
Water Line
G
W
S
(Utility Locations Approximate)
Power or Unknown
SD Storm Drain
CommunicationsC
P
Sanitary Sewer
U
GG
C
S
U
P
SD
SD
C
W
C C
U
S
S
SD
P
U
U
Ma
i
n

S
t
r
e
e
t
Angelo Avenue
Intermountain Lock
Security Supply
Closed-in-Place
Diesel UST
Gr
a
c
e

M
a
r
y

M
a
n
o
r
W ARE
H
O
U
S
E
SHO
W
R
O
O
M
ST AIRS
SHI
P
P
I
N
G

/
REC
E
I
V
I
N
G
P ARK
I
N
G

G
A
R
A
G
E
FIGURE 27/31/2024
MW-2
Monitoring Well
B-1
Soil Boring
Soil Boring (Western Geologic, 2021b)
GP-01
91.17 Groundwater Elev. (ft)
9
1
Groundwater Contour Line
(contour interval = 0.1 ft)
Groundwater
Flow Direction
GROUND FLOOR
RENDERING
B-2
B-1
GP-01
GP-02GP-03
GP-04
GP-05
MW-3 MW-1
MW-2
MW-4 MW-6
MW-5
MW-7
V
V
V
Proposed Soil Vapor Sample Point