DSHW-2024-005123

WASATCH ENVIRONMENTAL, INC.
ENVIRONMENTAL SCIENCE AND ENGINEERING

2410 WEST CALIFORNIA AVENUE
SALT LAKE CITY, UTAH 84104
PHONE [phone]
FAX [phone]
e-mail: [e-mail]
www.wasatch-environmental.com

ADDITONAL INVESTIGATION WORK PLAN
ARMS TECHNOLOGY MACHINE SHOP
2779 WEST DIRECTORS ROW
SALT LAKE CITY, UTAH

PROJECT NO. 2619-003C

PREPARED FOR:

MR. DOUG HANSEN
UTAH DEPARTMENT OF ENVIRONMENTAL QUALITY
DIVISION OF WASTE MANAGEMENT AND RADIATION CONTROL
195 NORTH 1950 WEST, 2ND FLOOR
P.O. BOX 144880
SALT LAKE CITY, UTAH 84114-4880

PREPARED BY:

WASATCH ENVIRONMENTAL, INC.
2410 WEST CALIFORNIA AVE
SALT LAKE CITY, UTAH 84104
801-972-8400
FAX: [phone]

MARCH 6, 2024
Arms Technology Machine Shop
Additional Investigation Work Plan Project No. 2619-003C
Wasatch Environmental, Inc. Page 1

TABLE OF CONTENTS

Section Page No.
1. INTRODUCTION AND OBJECTIVES ............................................................................................. 2
2. SITE BACKGROUND ...................................................................................................................... 2
3. SITE INVESTIGATION ACTIVITIES ................................................................................................ 4
3.1 Groundwater Monitoring Well Installation, Development, Surveying, and Sampling ......... 4
3.2 Off-Site Groundwater Sampling .......................................................................................... 5
3.3 Indoor Air Sampling............................................................................................................. 5
4. SAMPLING METHODOLOGY ......................................................................................................... 5
4.1 Groundwater Monitoring Well Installation, Development, Surveying, and Sampling ......... 5
4.2 Off-Site Groundwater Sampling .......................................................................................... 6
4.3 Indoor Air Sampling............................................................................................................. 7
5. REPORTING .................................................................................................................................... 7

FIGURES

Figure 1 – Site Location Map
Figure 2 – Historical and Proposed Sample Location Map

Arms Technology Machine Shop
Additional Investigation Work Plan Project No. 2619-003C
Wasatch Environmental, Inc. Page 2
ADDITIONAL INVESTIGATION WORK PLAN
ARMS TECHNOLOGY MACHINE SHOP
2779 WEST DIRECTORS ROW
SALT LAKE CITY, UTAH

1. INTRODUCTION AND OBJECTIVES

In accordance with the Utah Division of Waste Management and Radiation Control (DWMRC) request, we
have prepared this work plan for conducting investigative activities at the Arms Technology machine shop
(Site), owned by ATI Corporation, located at 2779 West Directors Row in Salt Lake City, Utah. See
Figure 1 for a Site Location Map. This work plan has been prepared to evaluate groundwater flow
direction, evaluate volatile organic compound (VOC) and semi-volatile organic compound (SVOC)
impacts to groundwater at the Site, and evaluate indoor air at the Site.

The objectives of this work plan are to:

 Install, develop, survey, and sample groundwater monitoring wells at the Site to evaluate the
groundwater flow direction, evaluate on-Site VOC and SVOC impacts to groundwater, and
evaluate the potential for VOC impacts to be migrating onto the Site from an off-Site source; and

 Collect indoor air samples to evaluate the potential for VOC impacts to on-Site commercial
workers.

This work plan describes the sampling and analytical procedures that will be used for sampling to be
performed during investigation activities at the Site.

2. SITE BACKGROUND

Wasatch completed a Phase I Environmental Site Assessment (ESA) dated September 21, 2023, for the
Site on behalf of Buchalter (the legal representative for the potential purchaser). This report identified the
following recognized environmental conditions (RECs) and recommended additional investigation be
completed:

 There is a potential for releases to the Site from the long-term use of the sump near the
southwest corner of the Site.

 There is a potential for releases to the Site from the long-term use of chemicals, lubricants, and
oils on the Site.

The Client requested that investigations be completed to evaluate the identified RECs.

On October 24, 2023, Wasatch completed four soil borings (GP-1 through GP-4) at the Site. Wasatch
advanced borings GP-1, GP-2, and GP-3 in the areas hydraulically downgradient of the building to
evaluate for impacts migrating away from the building, and boring GP-4 was advanced adjacent to the
sump to evaluate for potential releases in this area. Additionally, Wasatch collected six sub-slab soil gas
samples (SG-1 through SG-6) from beneath the on-Site building.

Based on the data collected Wasatch concluded the following:

 The suspected source area soil sample collected from boring GP-4 did not exhibit analyte
concentrations that exceeded their applicable United States Environmental Protection Agency
(U.S. EPA) Regional Screening Level (RSL) for Residential or Industrial Soil, except for arsenic.
Based on Wasatch’s experience the detected arsenic concentration is within the typical
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background range of 20 to 30 mg/kg for this area. Therefore, it is Wasatch’s opinion that the
detected concentration of arsenic in soil is representative of background concentrations and is not
considered to be a release.

 Chloroform was detected in all soil gas samples at concentrations ranging from 1.2 micrograms
per cubic meter (µg/m3) to 18 µg/m3. Chloroform is a common laboratory contaminant and is also
a breakdown compound of chlorine which is commonly observed in soil gas samples due to the
use of municipal water for irrigation or from leaking municipal water pipes in the area. Chloroform
is not considered to be a constituent of concern resulting from the suspected release of
chlorinated solvents, petroleum hydrocarbons, or metals at the Site.

 Soil gas samples SG-4 and SG-5 exhibited trichloroethene (TCE) concentrations that exceed the
applicable U.S. EPA Vapor Intrusion Screening Level (VISL) Residential and Commercial Target
Sub-Slab and Near-Source Soil Gas Concentrations (TSSGCs). The TCE concentrations in soil
gas indicate a release of TCE has likely occurred near soil gas samples SG-4 and SG-5. These
samples were collected near the sand trap and the former paint booth features which may be the
release point(s). Given the detected TCE in soil gas concentrations, there is a potential that the
rate of vapor intrusion into the building may result in TCE indoor air concentrations that exceed
the U.S. EPA RSL for Industrial Air.

 The arsenic concentrations detected in groundwater exceed the U.S. EPA MCL; however, these
concentrations are below the Utah Division of Water Quality (DWQ) Water Quality Standards
(GQS) for arsenic. Given the elevated background concentrations of arsenic in soil, it is
Wasatch’s opinion that the arsenic concentrations detected in groundwater are within the typical
background concentration range for this area. No other metals were detected at concentrations
that exceed their applicable U.S. EPA Maximum Contaminant Levels (MCLs).

 TCE was detected in all groundwater samples analyzed for volatile organic compounds (VOCs) at
concentrations ranging from 12.3 micrograms per liter (µg/L) to 75.4 µg/L. These concentrations
exceed the U.S. EPA MCL for TCE. These samples were collected hydraulically downgradient of
the on-Site building. Based on these data, it appears that a release of TCE may have originated
from the on-Site building.

 Based on the data obtained from boring GP-4, it does not appear that a release from the sump
has occurred.

 Given the totality of the data, it appears that a release of TCE has occurred at the Site and may
be located near the sand trap/paint booth features. Wasatch recommended that this release be
reported to the Utah Department of Environmental Quality (DEQ). Wasatch also recommended
that additional investigation be completed to define the nature and extent of these impacts.

On January 4, 2024, Wasatch completed eight additional borings (GP-5 through GP-12) at the Site to
further evaluate the on-Site VOC impacts to soil and groundwater. Based on the data Wasatch
concluded the following:

 Several soil samples were collected above the water table in suspected source areas. Low
concentrations of TCE were detected in the GP-11 (at 5 feet bgs) and GP-12 (at 6 feet bgs)
borings above the water table. This indicates that a minor surface release has likely occurred in
this area. However, these detected TCE concentrations are below the U.S. EPA RSL for
Residential and Industrial Soil and the U.S. EPA Protection of Groundwater Soil Screening Level
(PGWSSL).

 No chlorinated solvents (including TCE and cis-1,2-dichloroethene [CIS]) were detected at
concentrations exceeding their applicable U.S. EPA RSLs for Residential or Industrial Soil in the
soil samples collected. However, soil samples GP-9-10, GP-10-10, GP-10-15, GP-11-10, GP-11-
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15, and GP-12-12 (all collected at or below the water table) exhibited TCE concentrations that
exceed the U.S. EPA PGWSSL. This indicates there are soil impacts below the water table at
sufficient concentrations to result in impacts to groundwater at concentrations that exceed the
U.S. EPA MCL.

 TCE was detected in all groundwater samples at concentrations ranging from 4.88 to 47.3 µg/L.
These concentrations exceed the U.S. EPA MCL for TCE, except for groundwater sample GP-7-
17 (4.88 µg/L). Additionally, TCE is the only VOC that has been detected at a concentration
above the U.S. EPA MCL. Based on the groundwater data, TCE impacts to groundwater appear
to be present across the Site.

 Based on the totality of the groundwater data, TCE was detected along the northern, western,
eastern, and southern boundaries of the Site. This indicates that TCE impacts may be migrating
onto the Site, as the local groundwater flow direction is unknown but was assumed to be to the
north or northwest.

 Groundwater sample GP-11 exhibited the highest TCE concentration detected under the building.
Given this and that TCE was detected in the soil above the water table in this boring, it is
Wasatch’s opinion that this area likely represents a minor TCE source area under the building.
Groundwater monitoring wells should be installed to verify the groundwater flow direction.

 One groundwater sample (GP-9-30) was collected from a depth of 30 feet bgs. TCE was
detected at a concentration of 20.1 µg/L, which exceeds the U.S. EPA MCL. This indicates that
TCE impacts have migrated to at least 30 feet bgs at the Site.

 Given the totality of the data, it appears that a release of TCE has occurred at the Site and may
be located near the sand trap/paint booth features. Additionally, it appears that TCE impacts are
migrating onto the Site from an off-Site source, likely resulting in co-mingled plumes. Wasatch
recommends that this release be reported to the Utah DEQ. Wasatch also recommends that
additional investigation be completed to define the nature and extent of these impacts under the
guidance of the Utah DEQ.

Wasatch submitted a DWMRC application to enter into regulatory oversight with the Utah DWRMC on
February 20, 2024. The Site was accepted into the DWMRC Corrective Action program. DWMRC
requested that additional environmental investigations be completed.

3. SITE INVESTIGATION ACTIVITIES

3.1 Groundwater Monitoring Well Installation, Development, Surveying, and Sampling

Groundwater monitoring wells will be installed at the Site to evaluate VOC and SVOC impacts to
groundwater at the Site and to evaluate the potential for VOC and SVOC impacts that may be migrating
onto the Site from an off-Site source. The monitoring wells will be installed using the direct-push drilling
methods. Soil core samples would be continuously collected from 5-foot long by 1.5-inch diameter
discrete interval push samplers equipped with disposable polybutyrate liners. Soil samples would be
collected continuously and field logged by an experienced geologist. The field logging would include a
description of color, moisture content, consistency, odor, staining, and soil type based on the Unified Soil
Classification System and screened in the field with a photoionization detector (PID).

Monitoring well construction will consist of a 2.0-inch inner diameter (I.D.) polyvinyl chloride (PVC) well
with a 10-foot screen to a depth of approximately 15 to 20 feet below ground surface. The monitoring
wells will be developed to remove fines from the well screen prior to sampling using a pump or a
disposable polyethylene bailer.

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In order to determine groundwater flow direction at the facility, top-of-casing elevations will be surveyed
by Wasatch personnel using traditional survey equipment at each monitoring well location to within 0.01-
foot. Wasatch will obtain groundwater elevation measurements from each monitoring well using an
electronic water level probe. The probe will be decontaminated between each monitoring well with a
phosphate-free soap, rinsed with potable water, and then rinsed with de-ionized water. Based on the
measurements obtained, Wasatch will construct a potentiometric surface elevation contour map to
determine groundwater flow direction.

3.2 Off-Site Groundwater Sampling

Wasatch will request that two soil borings be completed on the adjoining west, assumed hydraulically
upgradient, property. Groundwater samples will be collected from these borings to evaluate VOC and
SVOC impacts to groundwater that may be migrating onto the Site from an off-Site source. The borings
will be installed using the direct-push drilling methods. Soil core samples would be continuously collected
from 5-foot long by 1.5-inch diameter discrete interval push samplers equipped with disposable
polybutyrate liners. Soil samples would be collected continuously and field logged by an experienced
geologist. The field logging would include a description of color, moisture content, consistency, odor,
staining, and soil type based on the Unified Soil Classification System and screened in the field with a
PID.

3.3 Indoor Air Sampling

To evaluate the potential risk to indoor air for commercial workers, Wasatch will collect indoor air samples
within the on-Site building.

To evaluate current background VOC concentrations present in ambient air in the vicinity of the Site so
that comparisons can be made to indoor air concentrations present at the on-Site building, Wasatch will
collect an outdoor air sample from the roof or an upwind area of the building.

4. SAMPLING METHODOLOGY

4.1 Groundwater Monitoring Well Installation, Development, Surveying, and Sampling

Chlorinated solvents have been identified at concentrations exceeding its U.S. EPA MCL within the
groundwater beneath the Site. Additionally, DWMRC requested that SVOC groundwater samples be
collected at the Site. Therefore, Wasatch proposes installing five monitoring wells to achieve the stated
objectives. The monitoring wells will be installed using the direct-push drill rig (GeoProbe 7822 or
equivalent), using hollow-stem auger or direct-push drilling techniques. Wasatch proposes installing the
following monitoring wells as depicted in Figure 2.

Each well will be installed to a depth ranging between 15 and 20 feet below ground surface (bgs)
depending on measured depth to groundwater. Each well will be completed with 10 feet of 2-inch 0.010-
slot schedule 40 polyvinyl chloride (PVC) wells screen with 2-inch PVC well casing attached to the top of
the well screen and extending to approximately 0.5 feet bgs. 10/20 silica sand will be placed as a filter
pack material around the screen interval and extending at least 2 feet above the top of the screen
interval. Bentonite chips will be placed from the top of the filter pack material up to ground surface and
hydrated to form a well seal. Each well will be completed with a flush-mount surface completion
consisting of an 8-inch steel well vault cemented in place.

Once each well is installed, each well will be properly developed using over pumping well development
techniques. A minimum of five well casing volumes of groundwater will be evacuated from each well;
however, additional volume will be removed to sufficiently remove additional fines from the wells based
on Wasatch’s discretion. All evacuated groundwater will be placed within a steel 55-gallon drum(s)
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labeled as pending analysis to facilitate proper disposal. All soil cuttings will also be placed within a steel
55-gallon drum and labeled as pending analysis to facilitate proper disposal.

In order to determine groundwater flow direction at the Site, top-of-casing elevations will be surveyed by
Wasatch personnel using traditional survey equipment at each monitoring well location to within 0.01-foot.
Wasatch will survey the top-of-casing of each well and reference them to a relative datum of 100.00 feet.
Wasatch will obtain groundwater elevation measurements from each monitoring well using an electronic
water level probe. The probe will be decontaminated between each monitoring well with a phosphate-
free soap, rinsed with potable water, and then rinsed with de-ionized water. Based on the measurements
obtained, Wasatch will construct a potentiometric surface elevation contour map to determine
groundwater flow direction.

The monitoring wells will be sampled using low-flow sampling techniques. Monitoring well sampling will
involve inserting ¼-inch outside diameter, low-density polyethylene tubing into the newly installed
monitoring well. The tubing will be run through a peristaltic pump, then to a flow cell to which a multi-
parameter AquaTroll 500 meter will be attached, and finally to a 5-gallon bucket to collect the purge
water. The initial water level would be measured in the monitoring well only and recorded prior to the
initiation of pumping. Once pumping is initiated, water levels, pumping rate, cumulative volume purged,
water temperature, specific conductivity, pH, oxygen reduction potential (ORP), dissolved oxygen (DO),
and turbidity will be recorded at three to five-minute intervals until either stabilization is achieved or the
monitoring well pumps dry. Pumping rates will be maintained at rates of 50 to 200 milliliters per minute to
minimize drawdown. Stabilization is defined as three consecutive measurement intervals where
temperature and specific conductivity were +/- 3%, pH was +/- 0.1, DO was +/-10% (or less than 0.5
mg/L), and turbidity was +/- 10% (or less than 5 nephelometric turbidity units [NTUs]). If the monitoring
well pumps dry, it will be allowed to recharge to a minimum of at least 90% of its static water level prior to
sampling. After stabilization is achieved, the tubing would be disconnected from the flow cell and the
groundwater sample would be dispensed into appropriate laboratory prepared containers.

Groundwater samples would be collected into appropriate containers with gloved hands and transported
under chain-of-custody, in an iced cooler to Chemtech-Ford Laboratories (CF) for analysis of VOCs using
U.S. EPA Method 8260D and SVOCs using U.S. EPA Method 8270E.

4.2 Off-Site Groundwater Sampling

These borings will be installed using the direct-push drilling methods. Soil core samples would be
continuously collected from 5-foot long by 1.5-inch diameter discrete interval push samplers equipped
with disposable polybutyrate liners. Soil samples would be collected continuously and field logged by an
experienced geologist. The field logging would include a description of color, moisture content,
consistency, odor, staining, and soil type based on the Unified Soil Classification System and screened in
the field with a PID.

Subsequent to the borings, a stainless-steel temporary well screen will be placed within the groundwater
to collect a groundwater sample. Groundwater would be purged from the boring in an attempt to reduce
the turbidity of the groundwater sample.

Groundwater samples would be collected into appropriate containers with gloved hands and transported
under chain-of-custody, in an iced cooler to CF for analysis of VOCs using U.S. EPA Method 8260D and
SVOCs using U.S. EPA Method 8270E.

Given that the adjoining west property owners may reject our request to collect groundwater samples
from their property. These borings may not be collected. Wasatch will provide proof of acceptance or
rejection of our request to sample the adjoining west property.

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4.3 Indoor Air Sampling

To evaluate potential soil vapor intrusion impacts in the on-Site building, Wasatch would collect six indoor
air samples, four within the warehouse/manufacturing area (IA-1 through IA-4) on the ground floor level
and two in the office areas (IA-5 and IA-6), and one outdoor air sample (OA-1) to be used as a
background sample. Proposed sample locations are shown in Figure 2.

Prior to collecting any indoor or outdoor air samples, Wasatch would complete a chemical inventory of the
interior of the building space at the Site. This would be done to verify that no products within the structure
contain any chemicals of concern. If products are found that contain the same chemicals of concern we
will be analyzing for, those products will be removed from the building for at least 7 days prior to
sampling. This will be completed to reduce the potential for false positives within the indoor air samples.
Wasatch would also interview the appropriate personnel to ascertain if potential activities within the
beginning have been conducted that may result in false positives (i.e. recent remodeling, floor stripping,
etc.)

The technique for collecting the indoor/outdoor air samples would begin by checking for a vacuum in each
6-liter Summa canister supplied by the laboratory. The initial vacuum would be recorded on the chain-of-
custody form. A 6-liter Summa canister would then be placed at an appropriate height for each sample
location. The sampling location height will generally be placed at breathing space height. A sample
regulator with a flow restrictor would be provided by the laboratory. A sample regulator would be
attached to each 6-liter Summa canister. The vacuum gauge on the flow restrictor would be monitored,
with decreasing vacuum indicating that ambient indoor air is being collected into the sample canister. The
samples would be collected for approximately 8 hours to represent a standard work day. The final
vacuums would be recorded on the chain-of-custody form provided. The valve on each Summa canister
would then be closed, the sample regulator would be removed, and a brass cap tightened to the inlets of
the Summa canisters. The Summa canisters would be labeled with the appropriate sample location, as
well as initial and final vacuum reading. Chain-of-custody documentation would be completed and the
samples would be delivered to Pace for the analysis of the standard list of VOCs using U.S. EPA Method
TO-15.

The laboratory will use level 3 quality assurance/quality control (QA/QC) reporting. A Data Validation
Report will be completed by an independent third-party for the groundwater, indoor air, and outdoor air
sample samples.

5. REPORTING

All data generated during the sampling will be documented in a final report. This report will include the
following:
 Narrative text,

 Data tables,

 Boring/well construction logs,

 Applicable maps,

 Chain of custody forms,

 Laboratory analytical results, and

 Third-party data validation report.

The results of the sampling and analysis will be summarized in the report. Data will be presented in table
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format. Conclusions based on the data as well as field observations will be included in the report. After
the laboratory data have been received, and reviewed, the report will be completed and submitted to ATI
Corporation prior to submission to the Utah DWMRC.

Sincerely,

WASATCH ENVIRONMENTAL, INC.

Blake Downey, P.G.
Vice President and Senior Project Hydrogeologist

Distribution: (1) Electronic - Addressee
(1) Electronic – Scott Farber (ATI Corporation)

The use or reuse of this information is restricted to the referenced document unless otherwise authorized.
Wasatch Environmental Copyright 2006
ARMS TECHNOLOGY MACHINE SHOP WEI 2619-003C
Figure 1 Site Location Map
Approximate
Location of Site
The use or reuse of this information is restricted to the referenced document unless otherwise authorized.
Wasatch Environmental Copyright 2006
ARMS TECHNOLOGY MACHINE SHOP WEI 2619-003C
Historical and Proposed Sample Location Map Figure 2
Directors Row
Cell Tower
Compressor
Compressor
Filter House
Filter HouseCoolant Drain Sump
Transformer
Closed-loop heated parking area
Shed w/ Drums
Floor drain
Capped
floor drain
Paint Booth
Coolant
Totes
Previous Boring Location
Previous Soil Gas Sample Location
Approximate Location of Site
SG-1
SG-3
SG-4
SG-2 SG-5
SG-6
GP-2
GP-1
GP-3
GP-4
Proposed Indoor/Outdoor Air Sample Location
LEGEND
GP-10GP-9 GP-5
GP-12
GP-11
GP-8
GP-7
GP-6
Fence
Sand Trap
w/ Discharge
Electrical Line
Proposed Monitoring Well Location
MW-3
MW-1
MW-2
MW-5
MW-4
IA-3
OA-1 IA-1
IA-2
IA-6IA-5
IA-4
Scale: 1-inch equals
approximately 54 feet
Assumed Groundwater
Flow Direction
Proposed Off-Site Soil Boring
GP-13
GP-14