DERR-2024-009402

Office of Land and Emergency Management
Office of Superfund Remediation and
Technology Innovation

FINAL

OPTIMIZATION REVIEW
WASATCH CHEMICAL CO. (LOT 6) SUPERFUND SITE
SALT LAKE CITY, UTAH

FINAL TECHNICAL MEMORANDUM
May 21, 2024

EPA Region 5 START V Contract
Document Tracking Number 1631c

www.clu-in.org/optimization | www.epa.gov/superfund/cleanup/postconstruction/optimize.htm
www.epa.gov/aboutepa/about-office-land-and-emergency-management

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
i
NOTICE AND DISCLAIMER
Work described herein was performed by Tetra Tech, Inc. (Tetra Tech) for the U.S.
Environmental Protection Agency (EPA). This final document was developed for EPA under the
Region 5 Superfund Technical Assessment and Response Team (START) V contract number
68HE0519D0005, under Task Order 68HE0520F0031, Task Order Line Item Number 0001BD001.
This optimization review is an independent study funded by EPA that focuses on opportunities
for optimization as related to protectiveness, cost-effectiveness, site closure, technical
improvements, and efficient use of resources at the Wasatch Chemical Co. (Lot 6) Superfund
Site in Salt Lake City, Utah. Detailed consideration of EPA policy was not part of the scope of
work for this review. This technical memorandum does not impose legally binding
requirements, confer legal rights, impose legal obligations, implement any statutory or
regulatory provisions, or change or substitute for any statutory or regulatory provisions.
Mention of trade names or commercial products does not constitute endorsement or
recommendation for use.
Recommendations are based on an independent evaluation of existing site information,
represent the technical views of the optimization review team, and are intended to help the
site team identify opportunities for improvements in the current site remediation strategy.
These recommendations do not constitute requirements for future action; rather, they are
provided for consideration by EPA and other site stakeholders including the Utah Department
of Environmental Quality (Utah DEQ).
While certain recommendations may provide specific details to consider during
implementation, these recommendations are not meant to supersede other, more
comprehensive, planning documents such as work plans, sampling plans, and quality assurance
project plans (QAPP); nor are they intended to override applicable or relevant and appropriate
requirements (ARAR). Further analysis of recommendations, including review of EPA policy may
be needed before implementation.

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
ii
PREFACE
This technical memorandum was prepared as part of the National Strategy to Expand
Superfund Optimization Practices from Site Assessment to Site Completion implemented by the
U.S. Environmental Protection Agency (EPA) Office of Land and Emergency Management, Office
of Superfund Remediation and Technology Innovation (OSRTI)1. The project contact is as
follows:
Organization Key Contact Contact Information
United States
Environmental
Protection
Agency (EPA)
Kirby Biggs

National
Optimization
Program Manager
EPA Office of Land and Emergency Management
Office of Superfund Remediation and Technology Innovation
Technology Innovation and Field Services Division
1200 Pennsylvania Ave., NW (5203P)
Washington, DC 20460
[e-mail]
Phone: [phone]

1 EPA. 2012. Memorandum: Transmittal of the National Strategy to Expand Superfund Optimization Practices from Site
Assessment to Site Completion. From: James. E. Woolford, Director Office of Superfund Remediation and Technology Innovation
(OSRTI). To: Superfund National Policy Managers (Regions 1 – 10). Office of Solid Waste and Emergency Response (OSWER)
9200.3-75. September 28.

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
iii
ACRONYMS AND ABBREVIATIONS
μg/L micrograms per liter
μg/kg micrograms per kilogram
μg/m3 micrograms per cubic meter
1,1-DCE 1,1-dichloroethene
2,4-D 2,4-dichlorophenoxyacetic acid
amsl above mean sea level
ARAR applicable or relevant and appropriate requirements
ARD Assessment and Remediation Division
BSHW Utah Bureau of Solid and Hazardous Waste
BTEX benzene, toluene, ethylbenzene, xylenes
bgs below ground surface
cis-1,2-DCE cis-1,2-dichloroethene
CERCLA Comprehensive Environmental Response, Cleanup and Liability Act
cm/sec centimeters per second
COC contaminant of concern
COVID-19 coronavirus disease 2019
CPT cone penetrometer testing
CSM conceptual site model
CVOC chlorinated volatile organic compound
DCE dichloroethene
DERR Division of Environmental Response and Remediation
DNAPL dense non-aqueous phase liquid
DPT direct-push technology
ELCR excess lifetime cancer risk
EPA U.S. Environmental Protection Agency
ERD enhanced reductive dechlorination
ESD Explanation of Significant Differences
FS feasibility study
FFS focused feasibility study

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
iv
ft feet; foot
ft/day feet per day
ft/yr feet per year
ft2/day square feet per day
HDPE high-density polyethylene
HI hazard index
HQ Headquarters
HRSC high-resolution site characterization
IA indoor air
IC institutional control
ISCO in-situ chemical oxidation
ISV in-situ vitrification
kg kilograms
MCL Maximum Contaminant Level
mg/kg milligrams per kilogram
mg/L milligrams per liter
Mgal/day million gallons per day
MIP membrane interface probe
MNA monitored natural attenuation
NYDS North Yard Drain System
NPL National Priorities List
OU operable unit
O&M operations and maintenance
PCE tetrachloroethene
PCP pentachlorophenol
POTW Publicly Owned Treatment Works
PRP potentially responsible party
PVC polyvinyl chloride
RAO remedial action objective
RI remedial investigation
ROD Record of Decision

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
v
RSL regional screening level
SS sub-slab or sub-floor
SSL soil screening level
SSDS sub-slab depressurization system
SVOV semi-volatile organic compounds
TCE trichloroethene
TCL target compound list
TPH total petroleum hydrocarbon
trans-1,2-DCE trans-1,2-dichloroethene
UDEQ Utah Department of Environmental Quality
UDWR Utah Division of Water Rights
UPDES Utah Pollution Discharge Elimination System
VC vinyl chloride
VI vapor intrusion
VIMS vapor intrusion mitigation system
VISL vapor intrusion screening level
VOC volatile organic compound

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
vi
TABLE OF CONTENTS
Section Page
NOTICE AND DISCLAIMER .................................................................................................................I
PREFACE ...........................................................................................................................................II
ACRONYMS AND ABBREVIATIONS ................................................................................................. III
TABLE OF CONTENTS...................................................................................................................... VI
1.0 INTRODUCTION AND OBJECTIVES ......................................................................................... 1
2.0 OPTIMIZATION REVIEW TEAM AND APPROACH ................................................................... 2
3.0 INFORMATION REVIEWED ..................................................................................................... 3
4.0 SITE BACKGROUND AND UNDERSTANDING .......................................................................... 5
4.1 Site Location and Key Site Features .............................................................................. 5
4.2 Climate .......................................................................................................................... 5
4.3 Geology, Hydrogeology and Groundwater Use ............................................................ 6
Regional Geology and Hydrogeology ................................................................ 6
Site Geology ...................................................................................................... 6
Site Hydrogeology ............................................................................................. 7
Groundwater Use .............................................................................................. 8
4.4 Regulatory History, Decision Documents and Cleanup Levels ..................................... 9
Remedial Investigation, ROD, and Remedial Action ....................................... 10
Additional Shallow Groundwater Investigations ............................................ 13
Deeper Groundwater Investigations ............................................................... 13
Additional Shallow Soil Focused Investigations .............................................. 14
Indoor Air Investigations ................................................................................. 14
North Yard Drain Replacement ....................................................................... 15
Institutional Controls (IC) ................................................................................ 15
Five-Year Reviews ............................................................................................ 16
4.5 Overview of Contaminant Distribution ....................................................................... 17
Soil Contamination .......................................................................................... 17
Soil Vapor Contamination ............................................................................... 18
Groundwater Contamination .......................................................................... 19
5.0 FINDINGS .............................................................................................................................. 22
5.1 Soil Contamination ...................................................................................................... 22
5.2 Extent of Shallow Groundwater Contamination/700 West Ditch .............................. 22
5.3 Conceptual Site Model ................................................................................................ 23
5.4 Remedial Objectives, Timeframes and Contaminant Sources ................................... 23
5.5 Soil Vapor/Vapor Intrusion ......................................................................................... 24

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
vii
5.6 Annual Remedy Operations, Maintenance and Monitoring Costs ............................. 25
5.7 Alternative Remedial Approaches .............................................................................. 26
5.8 Resource Use and Efficiency ....................................................................................... 26
6.0 RECOMMENDATIONS .......................................................................................................... 27
6.1 Recommendations to Improve the Remedy’s Ability to Achieve Protectiveness
Goals ........................................................................................................................... 27
Additional Source Area Identification and Characterization .......................... 27
Additional Evaluation of the Vapor Intrusion Pathway .................................. 28
Sampling of 700W Ditch ................................................................................. 29
6.2 Recommendations to Improve Cost-Effectiveness..................................................... 30
6.3 Recommendations for Technical Improvement ......................................................... 30
6.4 Recommendations for Site Completion (Remedy Approach Moving Forward) ......... 30
6.5 Recommendations for Conservation of Resources .................................................... 32
6.6 Estimated Costs and Savings ....................................................................................... 32

TABLES
Table 1: Optimization Review Team ............................................................................................... 2
Table 2: Optimization Review Contributors.................................................................................... 2
Table 3: Chronology of Site Cleanup Events and Activities ............................................................ 9
Table 4: Estimated Annual Remediation and Monitoring Costs ................................................... 25
Table 5: Summary of Estimated Costs and Savings ...................................................................... 32

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
viii
ATTACHMENTS
Attachment A: Select Figures from Site Documents
Figure A-1: Site Location Map
Figure A-2: Site Property and Institutional Controls
Figure A-3: Groundwater Monitoring Network
Figure A-4: Cross Section Soil/Sediment Classification Cross Section A-A’
Figure A-5: Shallow Groundwater Elevations – April 2022
Figure A-6: Deeper Zone 1 Groundwater Elevations – April 2022
Figure A-7: Focused Shallow Soil Investigation Area – May 2013
Figure A-8: Focused Shallow Soil Investigation Boring Locations and Results Relative to
Screening Levels – May 2013
Figure A-9: Tetrachloroethene Detected in Shallow Groundwater – April and May 2022
Figure A-10: Trichloroethene Detected in Shallow Groundwater – April and May 2022
Figure A-11: 1,1-Dichloroethene Detected in Shallow Groundwater – April and May 2022
Figure A-12: Vinyl Chloride Detected in Shallow Groundwater – April and May 2022
Figure A-13: Pentachlorophenol Detected in Shallow Groundwater – April and May 2022
Figure A-14: Shallow Groundwater Stability Evaluation Results
Figure A-15: Vinyl Chloride Concentration Trends at Select Wells – 2016-2022

Attachment B: Select Tables from Site Documents
Table B-1: Soil and Sludge Indicator COCs and Action Levels
Table B-2: Groundwater COC Action Levels
Table B-3: Focused Shallow Soil Investigation Results – 2013
Table B-4: Groundwater Monitoring Results – April-May 2022
Table B-5: Concentrations in Wells with Exceedances of MCLs – 2017-2021

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
1
1.0 INTRODUCTION AND OBJECTIVES
This technical memorandum provides the findings and recommendations of an independent
optimization review of remedial activities at the Wasatch Chemical Co. Superfund Site, located
in Salt Lake City, Utah. Figure A-1 in Attachment A shows the site location.
Findings and recommendations are based on the optimization review team’s review of site
documents and data and information obtained from interviews and conversations with the site
team through project conference calls, emails, and written correspondence.
U.S. Environmental Protection Agency (EPA) Region 8 requested this independent optimization
review of site-wide groundwater contamination and current remediation systems to obtain
recommendations on:
• Identification of a path forward for an effective and efficient remedy; and
• Development of a site completion strategy.
An additional objective of this optimization review was to review the conceptual site model
(CSM) in the context of progress toward remedial goals, based on historical and recent data;
and, if necessary, refine the CSM to support future decisions regarding further investigative or
remedial activity. The purpose of the review of the CSM is to ensure it is current and a valid tool
to support site management decisions, regardless of whether or not updating the CSM or
additional work are ultimately warranted.
Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
2
2.0 OPTIMIZATION REVIEW TEAM AND APPROACH
The optimization review team included independent, third-party technical personnel from Tetra
Tech who collaborated with representatives of EPA Headquarters (HQ), Office of Land and
Emergency Management (OLEM), Office of Superfund Remediation and Technology Innovation
(OSRTI), EPA Region 8, and the Utah Department of Environmental Quality (Utah DEQ). Table 1
lists the members of the optimization review team.
Table 1: Optimization Review Team
Name Organization Title
Kirby Biggs EPA OLEM OSRTI TIFSD National Optimization Program Manager
Vanessa Van Note EPA OLEM OSRTI TIFSD Environmental Engineer
Amanda Van Epps EPA OLEM OSRTI ARD CPCMB Environmental Engineer
Jody Edwards, P.G. Tetra Tech, Inc. Principal Hydrogeologist; Program Manager
Chit Christian Tetra Tech, Inc. Environmental Engineer
Guy Montfort, P.G. Tetra Tech, Inc. Principal Hydrogeologist
Peter Rich, P.E. Tetra Tech, Inc. Principal Engineer
Jen Johnson Tetra Tech, Inc. Project Coordinator
Notes: EPA = U.S. Environmental Protection Agency; OLEM = Office of Land and Emergency Management; OSRTI = Office of
Superfund Remediation Technology Innovation; ARD = Assessment and Remediation Division; CPCMB = Construction and Post-
Construction Management Branch; P.E. Professional Engineer; P.G. = Professional Geologist
On January 12, 2023, representatives from EPA, Utah DEQ, Dominion Energy, Stantec, and Tetra
Tech convened a conference call to exchange information and address preliminary questions
from the optimization review team. Attendees included the optimization review team and
individuals identified in Table 2.
Table 2: Optimization Review Contributors
Name Organization Title
Angela Zachman EPA Region 8 Remedial Project Manager
Christina Progess EPA Region 8 Section Chief, Group B Remedial Branch
Ian Bowen EPA Region 8 Hydrogeologist / Regional Optimization Liaison
Tony Howes Utah DEQ Project Manager
Kris Benson Dominion Energy Environmental Compliance Coordinator
Donald Hintz Dominion Energy Geological / Environmental Consultant
Tina Maniatis Dominion Energy Manager, Gas Distribution Environmental Compliance
Gordon Murdock Dominion Energy Director of Safety and Environmental Compliance
Adam Plonsky Dominion Energy Environmental Compliance Manager
Dennis Slade Dominion Energy Manager, Corporate Waste Hazardous Materials and
Remediation
Stacey Arens Stantec Technical Expert, Chemical Environmental Engineer
Susan Eyzaguirre Stantec Project Manager
Notes: EPA = U.S. Environmental Protection Agency; Utah DEQ = Utah Department of Environmental Quality

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
3
3.0 INFORMATION REVIEWED
The optimization review team reviewed the following site-related and regulatory guidance
documents as part of this optimization review:
• Entrada Industries Inc., 1996. Monthly Progress Report No. 42. March 5.
• Harding Lawson Associates, 1996. Construction Completion Report, Remedial
Action/Remedial Design – Soils, Wasatch Chemical Site, Salt Lake City, Utah. January 15.
• MWH, Technical Memorandum for Wellfield Operation Modification, Wasatch Chemical
Site, Salt Lake City, Utah.
• MWH, 2003. Wasatch Chemical Site Progress Report No. 79. July 10.
• MWH, 2008. Wasatch Chemical Site Progress Report No. 89. July 18.
• MWH, 2009. Wasatch Chemical Site Groundwater Flow and Contaminant Transport
Modeling Report. October.
• MWH, 2010. Wasatch Chemical Site, Draft Groundwater Remediation Focused Feasibility
Study Report. February.
• MWH, 2012. Memorandum – Wasatch Chemical Site Technical Memorandum – Final
Groundwater Monitoring Well Installation Documentation. February 8.
• MWH, 2013. Email Correspondence – Wasatch – Deeper GW Inv Update No. 6.
September 5.
• MWH-Stantec, 2017a. Final Deeper Groundwater Monitoring Well Installation and
Sampling Plan. Wasatch Chemical Site. February 21.
• MWH-Stantec. 2017b. Human Health Risk Assessment for Shallow Soils in the Focused
Investigation Area at the Wasatch Chemical Site, Salt Lake City, Utah. August 28.
• National Weather Service, 2023. Salt Lake City Climate Book. On-Line Resource at
https://www.weather.gov/media/slc/ClimateBook. June.
• Questar InfoComm, 2008. Letter – Wasatch Chemical Site, Revision of Record of Decision
/ Consent Decree to Change Permanent Remedy and Update Documents. August 27.
• Questar InfoComm, 2016. Focused Shallow Soil and Deeper Groundwater Investigation
and Sentry Well Installation Report. November.
• Questar InfoComm. 2018. Wasatch Chemical Site – Final Indoor Air Investigation
Summary Report. January.
• Stantec, 2017. Deeper Monitoring Well Installation and Initial Groundwater Sampling
Report. November 30.
• Stantec, 2022a. Final Indoor Air Sampling Summary Report, Wasatch Chemical Site.
February.
• Stantec, 2022b. Questar InfoComm Responses to U.S. Environmental Protection Agency
Comments on Wasatch Chemical Site Draft Indoor Air Sampling Report, April 2020.
February 1.

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
4
• Stantec, 2022c. Wasatch Chemical Site Progress Report No. 116. February 28.
• Stantec, 2022d. Wasatch Chemical Site Progress Report No. 117. October.
• U.S. District Court for the District of Utah Central Division, 1991. Consent Decree.
November 22.
• U.S. Environmental Protection Agency (EPA), 1991. Record of Decision, Wasatch
Chemical Site, Salt Lake City, Utah. March 29.
• EPA, 1995. Explanation of Significant Differences, Wasatch Chemical Co. (Lot 6).
November 30.
• EPA, 2002. Second Five-Year Review Report for Wasatch Chemical Site, Salt Lake City,
Utah. September.
• EPA, 2007. Third Five-Year Review Report for Wasatch Chemical National Priority List
Site, Salt Lake City, Utah. September.
• EPA, 2012. Fourth Five-Year Review Report for Wasatch Chemical Co. (Lot 6),
UTD000716399, Salt Lake City, Utah. September.
• EPA, 2017. Fifth Five-Year Review Report for Wasatch Chemical Co. (Lot 6) Superfund
Site, Salt Lake County, Utah. September.
• EPA, 2018. Comments on the Human Health Risk Assessment for Shallow Soils in the
Focused Investigation Area at the Wasatch Chemical Site, Salt Lake City, Utah – Agency
Comments. Correspondence from Sam Garcia, Remedial Project Manager, to Scott
Basset, Questar Corporation, February 20.
• EPA, 2022. Sixth Five-Year Review Report for Wasatch Chemical Co. (Lot 6) Superfund
Site, Salt Lake County, Utah. August.
• Utah Division of Water Rights, 2023. Online Database of Water Well Logs. Well
Information (www.waterrights.utah.gov/wellinfo).

Based on a preliminary review of available public scientific papers and the documents and data
provided, the optimization review team determined those listed above were most pertinent to
this optimization review effort.

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
5
4.0 SITE BACKGROUND AND UNDERSTANDING
This section summarizes site background information and the optimization review team’s
general understanding of the site. Section 5.0 provides additional details regarding some of
these items.
4.1 SITE LOCATION AND KEY SITE FEATURES
As shown on Figure A-1 in Attachment A, the former Wasatch Chemical (Wasatch) Site is
located near the intersection of 700 West Street and 2100 South Street in an industrial area of
Salt Lake City in Salt Lake County, Utah. The site lies to the west of Interstate I-15. The site area
is located between a rail line on the east and north; W2100S on the south, and a drainage ditch
(the 700W Ditch) followed by S700W on the west. As shown on Figure A-2 in Attachment A, the
approximately 18-acre site includes property owned by Questar InfoComm, Inc. (Questar) and
portions of adjacent properties. Intsel Steel West (formerly Steelco), a metals service and
distribution company, owns property on the north side of the site including the Intsel Steel
West office building and the Intsel Steel West warehouse. Peterson Plumbing Supply currently
owns the southern portion of the site including the Peterson Plumbing warehouse and former
KEPCO+ building. The nearest residential area is located approximately 0.25-mile northwest of
the site.
The site is located in the Great Salt Lake Valley area of the Great Basin approximately 5.5 miles
west of the west front of the Wasatch Range and 12 to13 miles east of the eastern side of the
Great Salt Lake. The site lies at an approximate surface elevation of 4,225 feet (ft) above mean
sea level (amsl). The site’s topography is flat, with an elevation variance of less than a few feet.
Most surface drainage flows westward toward the 700W Ditch that connects to other industrial
drainageways, with ultimate discharge to the Jordan River and Great Salt Lake.
From 1957 to 1971, Wasatch Chemical Company used the area to warehouse, produce, and
package industrial chemical products. From the 1970s to 1992, site operations included
blending and packaging of pesticides, herbicides, fertilizers, industrial chemicals, and cleaners.
The company also discharged wastewater into on-site tanks and evaporation ponds; and, onto
the ground. Tanks of xylene, toluene, hydrochloric acid, and chlorine (part of the “original tank
farm”) were located just north and west of MW-33D (immediately north of the eastern portion
of the current Peterson Plumbing Supply warehouse). Later, after the tank farm was removed,
this area was used as a “drum filling or drum handling area.” Additionally, a historic process
drain line, which conveyed chemical process wastes to the former evaporation pond, extended
south to north along the east side of the Peterson Plumbing Supply warehouse and a septic
tank and leach lines were located in the vicinity of the former evaporation pond (EPA 1991).
4.2 CLIMATE
The climate of Salt Lake City is continental, with cold winters and hot summers. Annual
precipitation in the Salt Lake City area ranges from approximately 18.5 inches to 25 inches and

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
6
is generally highest in the eastern districts of the city, at the foot of the mountains, and
decreases westward (National Weather Service 2023).
4.3 GEOLOGY, HYDROGEOLOGY AND GROUNDWATER USE
This section summarizes the optimization review team’s understanding of regional geology and
hydrogeology, site geology, site hydrogeology, and groundwater use.
Regional Geology and Hydrogeology
The Salt Lake Valley is a deep alluvial basin from which surface water and groundwater drain
towards the Jordan River and Great Salt Lake (located west and northwest of the site). The
valley contains up to 4,000 ft of saturated Quaternary-age basin-fill material composed of
primarily lacustrine and deltaic deposits, with some interbedded alluvial fan deposits along the
flanking mountain range fronts. The valley fill materials are primarily interbedded layers of clay,
silt, sand, and some gravel. Finer-grained sediments dominate the low-lying areas in the center
and northern portions of the valley. (MWH-Stantec 2017a).
In a regional context, the valley’s groundwater system is divided into three primary
hydrogeologic units: (1) a shallow unconfined aquifer; (2) a shallow confining zone; and (3) a
primary confined regional deep aquifer (portions of which are used for industrial and municipal
water supplies throughout the valley). The shallow unconfined aquifer is typically present in the
upper 50 ft of the basin-fill deposits, and due to low yields and poor water quality, is typically
not used for drinking water or other beneficial uses. The primary confined regional deep aquifer
is used for water production across the valley and ranges in thickness from approximately 850
to over 2,000 ft, with thickening toward the center of the valley. Between the shallow
unconfined aquifer and the primary confined aquifer are low permeability confining layers
consisting of clays, silts, and fine sands that collectively function as a confining bed but may
contain some thin saturated zones depending on location (Stantec 2017).
Local surface water bodies and the regional deep aquifer are generally recharged primarily by
runoff from snowmelt from the higher elevations of the Wasatch Range. The primary, confined,
regional deep aquifer is recharged along the base of the Wasatch Mountains where the
coarser-grained materials are closer to the surface. Groundwater in this zone generally flows
west toward the center of the valley. Regional sources of recharge to the shallow aquifer
include horizontal groundwater flow from upgradient areas to the east and southeast, and
upward leakage from the underlying confining unit (EPA 2022; Stantec 2017, 2022c, 2022d).
Site Geology
Site geology has been investigated through the installation of groundwater monitoring wells
and advancement of soil borings. The current monitoring well network is shown on Figure A-3
in Attachment A. Figure A-4 in Attachment A provides a cross section which shows the various
geologic units at the site.
The soil/sediments at the site consist mainly of silty and clayey sands, silty clay and clay, and
interbedded sand and silt layers that extend from the ground surface to at least 160 ft below

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
7
ground surface (bgs), as observed during deeper drilling activities conducted in 2011 and 2017,
and cone penetrometer testing (CPT) conducted in 2013 and 2014 within the focused
investigation area. The finest-grained material, consisting of clays and interbedded clays, were
identified primarily between depths of approximately 15 and 80 ft bgs. A limited amount of
coarser-grained material, such as silty sands and fine sands, was identified at depths between
approximately 80 and 90 ft bgs; these are underlain by interbedded clays, silts, and thinner
layers of fine sand. The deep monitoring wells at the site are completed in relatively higher
permeability deposits within the confining bed above the primary confined aquifer of the Salt
Lake Valley. Evidence of coarser-grained sequences representative of the deep primary
confined aquifer have not been observed in borings completed to date at the site (EPA 2022;
Stantec 2017, 2022c, 2022d).
Site Hydrogeology
The site is located in the central area of the valley, where horizontal hydraulic gradients are
very low and groundwater flows upward from the primary confined aquifer, through the
confining zone, and into the shallow unconfined aquifer. This water ultimately discharges into
the Jordan River or wetlands at the land surface (from which the water evaporates). The
horizontal component of groundwater flow through these units generally moves west-
northwest, towards the Jordan River and Great Salt Lake (MWH-Stantec 2017a).
Groundwater is typically encountered in the shallow unconfined aquifer at depths ranging from
2 to 6 ft bgs, with higher groundwater elevations observed in the spring and lower groundwater
elevations observed in the fall. The bottom of the shallow unconfined aquifer is defined at
approximately 25 to 26 ft bgs on site. Shallow groundwater flow at the site is generally to the
west-northwest. Based on measurements completed during routine monitoring, the horizontal
gradient within the shallow aquifer is approximately 0.002 and the flow velocity ranges from
approximately 7 to 10 ft per year, assuming an effective porosity value of 0.25 (typical for silty
sand), and hydraulic conductivity (K) of 2 to 3 ft per day (MWH 2009). CPT dissipation pressure
tests conducted during a focused investigation from 2013-2014 and groundwater elevations
observed in deeper monitoring wells installed in July 2017 indicate that groundwater below the
shallow unconfined aquifer is under positive (artesian) pressure.
Local sources of recharge to the shallow aquifer in the vicinity of the site include infiltration of
precipitation and irrigation over unpaved areas and inflow from the 700 West Ditch when
hydraulic conditions are conducive. Results of groundwater elevation monitoring of the nearby
shallow monitoring wells indicate that the ditch varies between being a gaining or losing water
body relative to the shallow aquifer, depending on seasonal fluctuations (EPA 2022; Stantec
2022d).
The original CSM focused on the shallow aquifer with the assumption of confining material
beneath (MWH 2010). Subsequent hydrogeologic investigations completed between 2010 and
2017 identified five different groundwater zones (based on depth) within the shallow aquifer,
as shown in Figure A-4 in Attachment A and described below (Stantec 2022c):

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
8
• Shallow Groundwater Zone (Shallow Zone): Monitoring wells, piezometers, and
extraction trenches are completed to depths up to approximately 25 ft bgs in this zone.
The majority of monitoring points at the site are completed in this zone and have been
monitored since 1995. This zone reportedly consists primarily of silty and sandy clays
with occasional interbedded sand layers or lenses that are not laterally continuous
across the site. (Stantec 2022c);
• Deeper Groundwater Zone 1 (Deeper Zone 1): Monitoring wells are completed to
depths between 45 and 56 ft bgs. Monitoring points completed in this zone include
wells MW-31D, MW-32D and MW-33D installed in 2011. (Stantec 2022c);
• Deeper Groundwater Zone 2 (Deeper Zone 2): Monitoring wells are completed to
depths between 88 and 91 ft bgs. Monitoring points completed in this zone include
wells MW-35D2, MW-36D2 and MW-37D2 installed in 2017 (Stantec 2022c);
• Deeper Groundwater Zone 3 (Deeper Zone 3): One monitoring well, MW-38D3, was
completed in this zone to a depth of 128 ft bgs in 2017 (Stantec 2022c); and
• Deeper Groundwater Zone 4 (Deeper Zone 4): One monitoring well, MW-39D4, was
completed in this zone to a depth of 157.8 ft bgs in 2017 (Stantec 2022c).
Although Deeper Groundwater Zones 1-4 at the site contain saturated sediments (in some
cases interbedded), these zones have been interpreted to be within the regional “confining
zone” that separates the shallow/unconfined aquifer from the primary regional deep aquifer
used for water supplies. No on-site monitoring wells are identified as being screened in the
primary regional deep aquifer; the depth to the regional deep aquifer on-site is therefore
presumed to be greater than 160 ft bgs; however, this has not been confirmed.
Figures A-5 and A-6 in Attachment A present groundwater elevations in the shallow zone and
Deeper Zone 1, respectively, in April 2022. The depicted flow in the shallow zone was to the
west/northwest in areas east of the 700W Ditch, and eastward (toward the ditch) in the area
immediately west of the ditch. Flow in Deeper Zone 1 was to the northwest.
Groundwater Use
Available water supply well logs in the Utah Division of Water Rights on-line water well log
database indicate that production wells in the area are generally greater than 150 ft deep (Utah
Division of Water Rights [UDWR]) 2023). The shallow, unconfined aquifer is typically limited to
the upper 50 ft of the basin-fill deposits, and due to low yields and poor water quality, is
typically not used for drinking water purposes although there is the potential for use in the
future (EPA 2022). The deep aquifer underlying the site is used for the region’s water supply
across the valley and ranges in thickness from approximately 850 ft to over 2,000 ft and
thickens toward the center of the valley. The depth to the deep aquifer on-site is unknown but
is reportedly greater than 160 ft (Stantec 2017; 2022d).
Businesses at the site connect to, and receive water from, the public water system, which is
operated by the Salt Lake City Department of Public Utilities. The nearest residential area is

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
9
located approximately 0.25 miles northwest of the site. Review of the State of Utah’s on-line
water well log database indicates records for numerous water supply wells in the area. The
reported depths of these wells generally appear to correlate with the reported depths of the
deep, regional confined aquifer or the lower portion of the confining zone. The shallowest well
in the near-site vicinity noted within the UDWR database (UDWR ID#57-1444) is located
approximately 1,200 ft west of the site along S900W and is reportedly 157 ft deep. Several
wells closer to the site are located directly to the northwest, across route S700W from the site,
and extract water from sand and gravel at depths between 200 and 400 ft bgs. The current
status and use of the wells represented in the on-line UDWR database is unknown; however,
the logs in the database appear to indicate that the wells were originally installed for use by
private residences and as commercial and industrial facilities (UDWR 2023).
4.4 REGULATORY HISTORY, DECISION DOCUMENTS AND CLEANUP LEVELS
Contamination at the site was brought to the attention of regulatory agencies in the mid-1980s.
The Utah Bureau of Solid and Hazardous Waste (BSHW) completed a preliminary site
assessment and site investigation in 1984. BSHW and EPA led more field investigations of
groundwater, surface water, soils and sediments in 1985 and 1986. In June 1986, in
cooperation with BSHW, an EPA emergency removal action removed approximately 50 drums,
cylinders, and other containers of chemical waste from the site and provided temporary on-site
storage of several drums containing dioxin waste.
EPA proposed listing the site on the National Priorities List (NPL) in 1987 and the site was added
to the NPL in February 1991. Site potentially responsible parties (PRP) conducted the Remedial
Investigation (RI) in 1988-89 and an endangerment assessment in 1990. In August 1990, the
PRPs completed a Feasibility Study (FS) for both soil and groundwater remediation alternatives
(HLA 1990a). The Record of Decision (ROD) (EPA 1991) and a Consent Decree (U.S. District Court
1991) were completed and signed in 1991. Based on data collected after the ROD was signed,
EPA prepared an Explanation of Significant Differences (ESD) in November 1995 to document an
extension of the site boundary based on additional groundwater delineation and deletion of a
site paving requirement.
Table 3 provides a summary of key site remediation history milestones and dates for the site.
Table 3: Chronology of Site Cleanup Events and Activities
Date Event/Activity
1986 U.S. Environmental Protection Agency (EPA) Site Inspection for Removal Action
1988-1989 EPA Remedial Investigation (RI)
1990 Feasibility Study (FS) completed
1991 ROD and Consent Decree; Site added to NPL
1991-1995 Source areas and soils remediated; Groundwater remediation initiated
1997 First 5-Year Review
2002 Second 5-Year Review
2003 Operation of the groundwater remediation system discontinued to assess viability of
monitored natural attenuation (MNA); MNA subsequently implemented
2004 – 2006 Enhanced in-situ bioremediation pilot test

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
10
Date Event/Activity
2007 Third 5-Year Review; vapor intrusion (VI) identified as a potential risk
2010 Draft Focused Feasibility Study (FFS) for groundwater remediation in shallow zone
2011 Additional deep well MW-33D installed
2012 Fourth 5-Year Review; initial indoor air sampling
2013 Focused shallow soil investigation
2015 Second indoor air sampling event
2016 Additional deep groundwater investigation
2017 Fifth 5-Year Review; Shallow Soil Human Health Risk Assessment (HHRA); third indoor
air sampling event (including sub-slab sampling)
2019 Fourth indoor air sampling event
2021 North Yard Storm Sewer Drain replaced
2022 Sixth 5-Year Review; Indoor Air Investigation Report prepared
1995-2022 Groundwater Monitoring continued

Indicator chemicals, representing the most prevalent, mobile, persistent, and toxic compounds
at the site, are identified in the ROD for sludges, soils, and shallow groundwater (for compliance
monitoring). Groundwater deeper than approximately 25 ft bgs and vapor intrusion (VI) into
on-site commercial-use buildings were not identified as potential concerns in the ROD;
however, these were subsequently investigated between 2007 and present. The site continues
to be federally regulated under CERCLA. The site consists of one operable unit (OU), which
includes contaminated soil and groundwater.
The following subsections provide a summary of key investigation and remedial activities at the
site.
Remedial Investigation, ROD, and Remedial Action
Media investigated at the site includes waste (sludge and liquid), soil, sediment, surface water,
groundwater, and air. For each medium, except air, samples were collected and analyzed for
volatile organic compounds (VOC), semi-volatile organic compounds (SVOC), herbicides,
pesticides, dioxins/furans, and metals. Air samples were analyzed for VOCs only. The
endangerment assessment selected 12 indicator chemicals and identified risks to three
potential receptor populations: off-site residents, off-site workers, and on-site workers.
Primary exposure pathways identified included incidental ingestion of soil, dermal contact with
soil, and inhalation of fugitive dust. The PRPs and EPA made subsequent calculations to
evaluate potential risks associated with future on-site worker exposures, residential exposures,
and acute exposures; based on site hydrogeology, EPA and UDEQ identified the potential for
future human exposure to contaminated groundwater.
Primary indicator chemicals included VOCs and SVOCs, pesticides, and dioxins and furans for
most of the site. However, a total petroleum hydrocarbon (TPH) standard was used to delineate
and remediate an area of petroleum hydrocarbon-impacted soil in the southeastern part of the
site (to the north and northeast of what is now the Peterson Plumbing Supply warehouse).

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
11
Remedial action objectives (RAOs) identified in the ROD include:
• Control present and future risks posed by direct contact with and ingestion of soils,
sludges, and groundwater.
• Control the migration of contaminants from soils and sludges to groundwater.
• Prevent future human exposure to residual contamination in soils and dioxin removal
wastes.
The remedy selected for the site in the ROD (EPA 1991) and ESD (EPA 1995) included:
• Excavation of all soils containing indicator chemicals above action levels and sludges
from the yard and process drain systems and the septic system;
• Excavation and landfarming of about 1,000 cubic yards of hydrocarbon-contaminated
soils;
• Consolidation of these contaminated materials and dioxin removal wastes in the former
evaporation pond, covered by a layer of clean soil;
• Treatment of staged soils, sludges and dioxin removal wastes by thermal destruction of
indicator chemicals through in-situ vitrification (ISV);
• Extraction of contaminated groundwater on site until Maximum Contaminant Levels
(MCL) are met and treatment, to the extent necessary, of extracted groundwater by air
stripping to meet publicly owned treatment works or Utah pollution discharge
elimination system standards;
• Disposal of any residuals remaining from the treatment of groundwater at a hazardous
material disposal facility off site; and
• As an extra precautionary measure, implementation of institutional controls (IC) such as
deed restrictions, denial of well permits or acquisition of water rights, as practicable and
to the extent allowable by law (EPA 2022).
The cleanup levels (action levels) for soils and sludges established by the ROD and ESD were
based on direct contact risk. The ROD did not establish soil action levels for protection of
groundwater from leaching of contaminants from soil to groundwater. Table B-1 and B-2 in
Attachment B list the ROD action levels for site cleanup.
In 2004, 2,4-dichlorophenoxyacetic acid (2,4-D) was removed from the site groundwater
contaminant of concern (COC) list because this COC had not been detected in several rounds of
sampling. Vinyl chloride (VC), a degradation product of trichloroethene (TCE), was added as a
monitoring parameter, and is included in the list of current analytes for groundwater
monitoring.
The PRP implemented the remedial action (RA) specified in the ROD in four stages, as follows
(EPA 2022):

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
12
• Remedial Stage 1 included excavation and landfarming of hydrocarbon-contaminated
material from the area immediately north of what is now the Peterson Plumbing Supply
warehouse. Excavation activities were performed from October 1992 to April 1993 and
removed approximately 1,000 cubic yards of hydrocarbon-contaminated material and
treated the soil in a landfarm containment cell in the south-central area of the site.
Excavations reportedly extended to 2 ft below the water table. Treated soil that met the
TPH action level was used as backfill. Soils still exceeding the TPH action level after
treatment were placed in an on-site evaporation pond with soil, sludges, and debris
from other parts of the site for ISV treatment. The PRP completed the landfarming
portion of Remedial Stage 1 in 1994 (Harding Lawson Associates 1996; EPA 2022).
• Remedial Stage 2 involved excavation and/or consolidation of contaminated debris,
soils, and sludges from various locations around the site; dioxin removal waste; and the
contents in the former evaporation pond for treatment by ISV. The residual soils from
the landfarming RA in excess of TPH action levels were also placed on top of these
contaminated materials. Soils were presumably excavated if they were above industrial
exposure-based action levels specified in the ROD. The depth of the excavations was
reportedly 2 ft below the water table. The ISV treated approximately 5,200 tons of
material “primarily by thermal destruction” to the industrial exposure, risk-based action
levels specified in the ROD. ISV was completed in 1996. EPA and UDEQ determined that
remedial activities had attained performance standards for soils, sludges, and dioxin
removal wastes and issued a Construction Completion Report for the soils remedy in
January 1996 (Harding Lawson Associates 1996; EPA 2022).
• Remedial Stages 3 and 4 included groundwater extraction and treatment and a
groundwater pilot study of alternative remedies, respectively. Groundwater extraction
and treatment (Remedial Stage 3) started in 1995. The groundwater extraction system
eventually included (1) eight extraction wells (EX-01, EX-04, EX-05, EX-07, EX-08, EX-09,
MW-20 and MW-21) located throughout the site, and (2) two extraction trenches – ES-
01 (near well EX-01 and the Peterson Plumbing Supply warehouse) and EX-11 (west and
directly downgradient from the former evaporation pond/ISV area). Extracted
groundwater was treated by air stripping to meet Publicly Owned Treatment Works
(POTW) or Utah Pollution Discharge Elimination System (UPDES) standards (EPA 2017,
2022; Stantec 2022c, 2022d).
In July 2001, 11 monitoring and extraction wells were abandoned with EPA and UDEQ approval.
In October 2001, the PRP proposed a modification to the groundwater extraction scheme to
pump only from two extraction trenches, EX-11 and ES-01. Capture zone analysis modeling
evaluated the minimum pumping rates needed at these two locations to ensure hydraulic
containment of groundwater contaminants. EPA approved the two-location pumping scenario
in December 2001, and the modification was implemented later that month.
The ROD specified that groundwater be extracted until action levels are achieved; however, the
ROD acknowledged that it may not always be possible to reach MCLs or proposed MCLs
through (what was then) “currently available technology.” The ROD stated that the extraction

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
13
system’s performance standards and the remedy may be reevaluated by EPA and UDEQ if
contaminant levels ceased to decline and remained at levels above the performance standards.
The Consent Decree presents a detailed process of how groundwater treatment performance
standards for the site may be waived or modified based on technical impracticability. The
remedial goals for groundwater remain MCLs, as specified in the ROD. Accordingly, EPA
approved shutting the pump-and-treat system down in a letter dated October 23, 2002, and in
a January 9, 2003 letter approved Questar's Monitored Natural Attenuation Work Plan. EPA did
not approve MNA as a remedy, but did approve implementation of a "well-defined monitoring
program" to "ascertain the effect natural attenuation has on improving the water quality at the
Site."
Additional Shallow Groundwater Investigations
In 2004, in an effort to accelerate the degradation of chlorinated VOCs in groundwater at the
site, EPA approved an enhanced in-situ bioremediation pilot study. Results from the pilot tests
conducted from 2004-2006 indicated substantial mass reduction of the COCs in areas of
relatively higher permeability sands, but limited impact in areas where lower permeability silts
and clays were more prevalent (EPA 2022).
In 2010, the PRP completed a Draft Groundwater Remediation Focused Feasibility Study (FFS)
to identify goals, objectives, and remediation alternatives based on the pilot study results
(MWH 2010). The FFS evaluated five alternatives to potentially enhance the reduction of
contaminant mass and shorten remedial timeframes; no action; resumption of extraction and
treatment; enhanced reductive dechlorination (ERD)/biological treatment; MNA, and electrical
resistance heating (ERH). The comparison of alternatives assumed that active source treatment
(ERD and ERH) would cover a relatively large area. Based on technical feasibility, cost, and
comparison of remedial timeframes, the FFS concluded that MNA was the preferred alternative
moving forward.
MNA and monitoring of the shallow aquifer are ongoing. Shallow groundwater is sampled semi-
annually and analyzed for COCs, geochemical, and MNA indicator parameters.
Shallow groundwater data for MW-30 (installed in 2011 and located on the downgradient
[western] edge of the site), indicated an additional sentry well was needed to monitor potential
dissolved phase contaminant migration. The PRP installed a new shallow sentry well (MW-34)
outside the western site boundary and west of the 700W Ditch in June 2013. The well is 20 ft
deep and completed with a 10-foot screen in the shallow groundwater zone. The PRP has since
collected and analyzed samples from MW-34 over nineteen monitoring events between 2013
and 2022. Analytical results for all chlorinated VOC COCs were at concentrations below MCLs
indicating that shallow groundwater contamination did not migrate west of the 700W Ditch
(EPA 2022).
Deeper Groundwater Investigations
In October 2011, three deeper monitoring wells were installed in the southeastern part of the
site. The wells were installed into what is now identified as Deeper Zone 1 to determine
whether deeper groundwater (from 25 to 160 ft bgs) was affected by site contaminants. A

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
14
focused deeper groundwater investigation performed in 2013/2014 using CPT within
approximately 300 ft of MW-33D collected hydrogeologic data, geotechnical field data, and
chemical analytical samples from depths ranging from 15 to 60 ft bgs (MWH-Stantec 2017).
COCs were detected in groundwater at concentrations above MCLs both north and west of
MW-33D. In 2017, five deeper monitoring wells were installed in Deeper Zones D2, D3 and D4
(see Figure A-4 in Attachment A) at depths ranging from 88 to 158 ft bgs. To date,
concentrations of VOCs and pentachlorophenol (PCP) in groundwater from these five wells
have been below MCLs (EPA 2022).
Additional Shallow Soil Focused Investigations
In October 2011, shallow subsurface soil and deeper groundwater contamination was detected
during installation of MW-33D. In 2013, the PRP’s contractor collected 91 shallow soil samples
in the immediate area around MW-33D. Borings were advanced using direct-push technology
(DPT) with soil samples collected above the groundwater table and approximately 1 foot into
the saturated zone using a dual tube sampling system. VOC samples were collected using En
Core® samplers2 (Questar Info COMM 2016). Figures A-7 and A-8 in Attachment A present the
soil boring locations and summarize and compare the soil analytical results to current EPA
regional screening levels (RSL). The target risk 10-6 cancer/hazard index [HI] of 1 noncancer for
industrial soil was exceeded for tetrachloroethylene (PCE), TCE, ethylbenzene, xylenes, or PCP
in samples collected from 17 of 53 boring locations in the 1.6-acre area. These 17 borings were
located within a 0.25-acre area around the east side, and to the north, of the Peterson
Plumbing Supply warehouse (MWH-Stantec 2017a).
In 2017, the PRP completed a HHRA to assess the risk posed to potential future underground
utility workers from chemicals detected in shallow soil and groundwater in the focused
investigation area. Results of the HHRA indicated that residual concentrations of contaminants
in soil in the focused investigation area did not pose an unacceptable human health risk
because exposures were limited by existing ICs (MWH-Stantec 2017b).
In its technical review comments on the HHRA, EPA noted that although no groundwater-based
industrial soil screening levels (SSL) (soil concentration limits based on potential for leaching to
groundwater) were available, the detected contaminant concentrations of TCE and several
other COCs in soil exceeded residential risk-based, and MCL-based, SSLs (EPA 2018). These
sample locations were primarily at, and to the northwest of, monitoring well MW-33D.
Indoor Air Investigations
In response to the third FYR Report (EPA 2008), the PRP submitted an environmental covenant
to the Utah DEQ that requires a risk evaluation related to contaminant VI before the approval
of any new building permits on the property. Since the filing of the environmental covenant,
VOCs have been detected in the shallow groundwater near occupied commercial buildings on
site. In 2012, the PRP began indoor air sampling at the three occupied buildings on site to
assess the potential for VI and potential risk to workers. Indoor air sampling was conducted in

2 https://envirotechonline.com/products/encore-sampler

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
15
2012, 2015, 2017, and 2019 at the Intsel West Office, the former KEPCO+ office building, and
the Peterson Plumbing Supply warehouse shown in Figure A-1 in Attachment A. These
sampling efforts also included a single sub-floor/sub-slab vapor sample, collected inside the
Peterson Plumbing Supply warehouse in 2017. Sub-slab vapor samples have not been collected
since 2019 (Questar InfoComm 2018; Stantec 2022a).
Data from four indoor air sampling events were used to assess the potential for VI and evaluate
potential unacceptable health risk to indoor workers. The results of the air sampling events are
discussed in more detail in Section 4.5.2.
A 2022 Air Sampling Report (Stantec 2022a) summarized the 2019 air data, recommended
indoor air sampling once every 5 years in the Peterson Plumbing Supply warehouse, and the
KEPCO+ and Intsel buildings, and included the following conclusions:
• “The cumulative noncancer hazard estimates for current/future industrial workers
exposed to VOCs detected in indoor air inside the three buildings are below EPA’s
acceptable HI of 1.
• The cumulative cancer risk for current/future industrial workers exposed to VOCs
detected in indoor air inside the Instel West Office building, KEPCO+ building, and
Peterson Plumbing warehouse space, and Peterson Plumbing office are within the
target risk management range of 1 x 10-6 to 1 x 10-4”.
North Yard Drain Replacement
The North Yard Drain System (NYDS) collects stormwater from approximately 3 acres of paved
area near Peterson Plumbing Supply and the former KEPCO+ building and discharges it into the
Salt Lake City stormwater management system at the 700W Ditch. The NYDS was replaced in
2021 to prevent infiltration of contaminated groundwater into Salt Lake City’s stormwater
collection system. The construction work included abandonment of the original NYDS; and
installation of high-density polyethylene (HDPE) piping and utility access holes, an oil/water
separator, a new collection sump with pump equipment; and new polyvinyl chloride (PVC)
discharge conveyance line (Stantec 2022c).
Institutional Controls (IC)
ICs have been implemented at the site to protect human health. The 1991 ROD (EPA 1991)
required implementation of ICs, such as deed restrictions, denial of well permits, or acquisition
of water rights, as practicable and to the extent allowable by law. The current environmental
covenant, which was entered between Questar, EPA, and UDEQ was recorded January 14,
2009, includes ICs that vary by parcel to restrict land use, require notification of building
demolition, and implement the diversion (use) of contaminated groundwater.
Figure A-2 in Attachment A presents a summary of the parcels and applicable ICs for each.
Physical access to the site is restricted through fencing and signage. Use of groundwater is
restricted by the UDWR for most of the parcels including the areas around and downgradient
from the former evaporation pond and the additional shallow soil investigation area. The

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
16
UDWR will advise Questar if any petitions are submitted to divert groundwater from beneath
any of the parcels comprising the site. The parcels comprising the main former chemical
manufacturing and handling areas (approximately the southern half of the site with the
exception of the parcels adjacent to the rail line on the east) are also subject to disturbance
restrictions. The current environmental covenant also includes provisions to address potential
VI into any proposed new buildings on most of the parcels on the site. Risks from indoor air VI
are to be assessed for any newly constructed occupied structure on the property. If indoor air
VI is determined to pose a significant risk, the risk must be mitigated. If a risk assessment is not
conducted, a passive vapor intrusion mitigation system (VIMS) will be required for any newly
constructed, occupied structures on the site. EPA is determining whether additional ICs are
necessary for parcels above the groundwater plume.
Five-Year Reviews
EPA has completed six (6) FYRs for this site. The 6th FYR, completed in August 2022, concluded
that the soil remedy is functioning as intended by the ROD (EPA 1991) and ESD (EPA 1995) (EPA
2022). EPA and UDEQ determined that remedial activities had attained performance standards
for soils, sludges, and dioxin removal wastes.
The 6th FYR (EPA 2022) concluded that the groundwater remedy is not functioning as intended
by the decision documents. Groundwater extraction and treatment was conducted from 1995
to 2003. Groundwater concentrations remain above MCLs in shallow groundwater on site. The
6th FYR concluded that overall groundwater conditions at the site had not demonstrated a
meaningful improvement since the 5th FYR (EPA 2017).
The 6th FYR (EPA 2022) found that current land use restrictions and groundwater ICs required as
part of the selected remedy were functioning. An environmental covenant preventing
disturbance is in place for the portions of the site owned by Questar InfoComm, Inc. and
Peterson Plumbing Supply; which includes all of the site with the exception of the northern
portion occupied by Intsel Steel. Other ICs addressing groundwater use limitations and VI
monitoring are in place for the remainder of the site. As previously discussed, groundwater use
is restricted for most of the parcels within or adjacent to the plume. Groundwater use at
remaining parcels is controlled by a permit process that sends a warning email notification to
UDEQ-Division of Environmental Response and Remediation (DERR) and EPA if there is a well
permit or groundwater use application for the site. The 6th FYR (EPA 2022) found that no
permits had been filed in the 5 prior years and that EPA was still determining whether
additional ICs were necessary for parcels located above the groundwater plume.
The 6th FYR (EPA 2022) also found that several changes occurred related to the human health-
based toxicity data for COCs at the site since the 5th FYR (EPA 2017). The original soil action
levels for TCE and dioxins exceeded EPA’s acceptable cancer risk range and/or noncancer HI of
1 for industrial use. For the ISV area, the treatment action level exceeded the RSL for industrial
land use. During the RA, soils were reportedly excavated to 2 ft below the water table to
“ensure the removal of all contamination.” Clean fill was reportedly placed on the evaporation
pond before ISV treatment and clean fill was later applied to grade the area. In-place ICs

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
17
restricted disturbance of the soil. Based on these considerations, the 6th FYR (EPA 2022)
concluded that the soil removal areas remained protective for industrial uses.
The 6th FYR (EPA 2022) discussed the potential for ongoing leaching of residual soil
contamination to groundwater. The 6th FYR (EPA 2022) stated that because these soils could
continue to function as a source of groundwater contamination, EPA was evaluating whether
additional soil activities may be beneficial to the groundwater remedy.
The 6th FYR (EPA 2022) also concluded that indoor air VI risks were within acceptable risk ranges
based on monitoring completed through 2019. As previously discussed, ICs are in place that
require VI monitoring and risk assessment; or presumptive mitigation in lieu of sampling, for
new construction at the site (EPA 2022).
4.5 OVERVIEW OF CONTAMINANT DISTRIBUTION
This section summarizes information regarding the locations and concentrations of
contaminants in site media, based on the results of investigations discussed previously.
Soil Contamination
The ROD’s soil excavation and treatment action levels (EPA 1991) (for example 103,000
micrograms per kilogram [μg/kg] for TCE and 22,000 μg/kg for PCE) were based on direct-
contact risk under an industrial exposure scenario. The action level for the excavation and
landfarming of shallow soils from the area immediately north and northeast of the building
(now occupied by Peterson Plumbing Supply) was 100 mg/kg of TPH and treated soils that met
this standard were backfilled into the excavation. The depth of excavation was reportedly to 2
feet below the uppermost water table.
Table B-1 in Attachment B summarizes the results of soil sampling and analyses conducted
subsequent to the RI and RA 2011-2013. Sample locations are shown in Figures A-7 and A-8 in
Attachment A. During the 2011 installation of well MW-33D near the northeast corner of the
Peterson Plumbing Supply warehouse, PCE (3,100,000 μg/kg) and TCE (78,000 μg/kg), which are
also COCs in groundwater, were detected in soil samples from just above the water table. Other
constituents (that are not groundwater COCs) were also detected in the soil samples, including
ethylbenzene, toluene, and xylenes (MWH-Stantec 2017b).
The shallow soil investigation conducted in 2013 evaluated the extent of contamination in a
1.6-acre area around the north and east sides of the Peterson Plumbing Supply warehouse
(Questar InfoComm 2016; MWH-Stantec 2017b). Sample depths typically ranged between 1.4
and 4.4 ft bgs. As shown on Table B-1 in Attachment B, detected concentrations of chlorinated
volatile organic compounds (CVOC) in soil were highest in samples from borings DPSS-14 on the
east side of the building (TCE at 25,000 μg/kg); and DPSS-24 (PCE at 5,700 μg/kg and TCE at
4,500 μg/kg) and DPSS-26 (PCE at 690,000 μg/kg) located north of the building northwest of
MW-33D. A subsequent risk assessment completed in 2017 indicated that constituents
exceeded industrial soil RSLs based on a 10-6 (cancer) risk and/or noncancer HI of 1, at 17 of
the 53 locations. Based on a target risk level of 10-4, one constituent at one location exceeded

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
18
the industrial soil RSLs. VOCs exceeding RSLs at one or more locations included PCE, TCE,
ethylbenzene, xylenes, and PCP (MWH-Stantec 2017a).
Soil Vapor Contamination
Soil vapor data for the site consist primarily of four rounds of indoor air sampling data, and one
sub-slab sample collected in conjunction with the third indoor air sampling event (Questar
InfoComm 2018; 2022a). Indoor air sampling was conducted in 2012, 2015, 2017, and 2019 at
the Intsel West Office, the former KEPCO+ office building, and the Peterson Plumbing Supply
warehouse shown in Figure A-1 in Attachment A. Results and conclusions for each sampling
event are briefly summarized below.
• March 2012. Indoor air samples were analyzed for TCE, dichloroethene (DCE) isomers,
and VC, and the CVOCs were not detected.
• December 2015. The analyte list for indoor air was expanded to include the 25 VOCs
previously detected in soil within 100 ft of the Peterson Plumbing Supply warehouse
during the 2013 focused shallow soil investigation. A site-specific human health risk
evaluation (HHRE) concluded that VOC concentrations in indoor air were acceptable,
except for naphthalene which was detected inside the Peterson Plumbing Supply office
space.
• February 2017. Indoor air samples were collected to assess risk to human health, and a
sub-floor vapor sample was collected beneath the Peterson Plumbing Supply office
space to assess whether interior sources or sub-floor vapors may be a potential source
for VOCs detected inside the office space. Site-related VOCs were detected in the sub-
floor vapor sample, including TCE at 46 micrograms per cubic meter (µg/m3) in air,
exceeding the generic target sub-slab vapor concentration of 15.9 µg/m3 and the indoor
air vapor intrusion screening level (VISL) of 0.478 µg/m3. However, based on the indoor
air sample data, the HHRE found no unacceptable risk to human health inside the office
space.
• July – August 2019. This fourth sampling event was conducted to provide additional
data and confirm the continued absence of unacceptable human health risks from
indoor air VI, and provide data to evaluate seasonal variability. The analyte list was
reduced from 25 to 16 analytes most likely to pose a risk to human health based on
historical air sampling and HHRE results. Data indicated that there were no
unacceptable human health risks from indoor air VI.
In summary, limited sub-slab vapor sampling and analysis indicated the presence of soil vapor
contamination including groundwater COCs beneath the Peterson Plumbing Supply warehouse;
however, indoor air sampling data and the HHRE indicated that contaminant concentrations in
indoor air were within acceptable ranges (Stantec 2022a), except for naphthalene during the
December 2015 sampling event. The source of the naphthalene in indoor air may have been
outdoor air, interior sources or vapor intrusion.

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
19
Groundwater Contamination
Groundwater contamination is present in the shallow aquifer, which is generally limited to the
upper 26 ft of the subsurface at the site, and the upper 50 ft regionally.
Shallow groundwater has been monitored across the site since 1995 (quarterly through 2000
and semiannually beginning in 2001). As of 2022, the shallow groundwater monitoring program
included 17 shallow sampling locations, nine that are monitored semiannually and eight that
are monitored annually. Eight deeper monitoring wells screened in Deeper Zones 1-4 are
sampled once every 2 years.
Groundwater samples are analyzed for the indicator chemicals specified in the 1991 ROD (PCE,
TCE, 1,1-dichloroethene [1,1-DCE], and PCP) and degradation products of CVOCs (cis-1,2-
dichloroethene [cis-1,2-DCE] and trans-1,2-dichloroethene [trans1,2-DCE] and VC). 2,4-D was
removed from the required monitoring list of COCs, and VC and other potential degradation
products were added to support evaluations of MNA effectiveness. Routine monitored
groundwater parameters do not presently include benzene, toluene, ethylbenzene, xylenes
(BTEX) compounds or naphthalene which were detected in shallow soils in 2013.
Based on groundwater monitoring data from 2017-2022, the shallow groundwater COC plume
extends across approximately the middle (on a north-south line) third of the site, covering an
area of about 7 to 8 acres as shown in Figure A-12 in Attachment A for VC. The contaminated
area extends approximately from the north side of the Peterson Plumbing Supply warehouse
northward to the vicinity of monitoring well MW-21 on the Instel area; and from near the
vicinity of the former evaporation ponds/ISV area on the east, westward to the western site
boundary. Groundwater contamination does not appear to be migrating to the area west of the
700W Ditch, based on monitoring data from wells west of the ditch. The distribution of
contaminants in light of the apparent westward groundwater flow direction suggests multiple
source areas (Stantec 2022c, 2022d).
Table B-4 in Attachment B summarizes groundwater analytical data from the spring 2022 event
(Stantec 2022d). Table B-5 in Attachment B summarizes CVOC exceedances in the shallow
groundwater zone for the period 2017-2021. Figures A-9 through A-15 in Attachment A
summarize results for various COCs and the assessment of plume stability. Groundwater COCs
and/or breakdown product concentrations are typically highest at locations of the former
extraction trench (EX-11) located directly west and downgradient from the former evaporation
pond/ISV area and former extraction wells EX-02 and EX-05. The last round of groundwater
analytical data reviewed (April 2022) indicated no detections of PCE. The maximum detection of
TCE was 19 µg/L in former extraction well EX-02; other TCE detections across the site were less
than 1 µg/L. The maximum VC concentration was detected in the sample from former
extraction well EX-11 at 460 µg/L; cis-1,2-DCE and trans-1,2-DCE were detected at 280 and 150
µg/L, respectively in this same sample. The April 2022 data (Stantec 2022d) indicates shallow
groundwater contamination extending to near the western site boundary (in the vicinity of the
property line). In well MW-30 (located just inside the western/downgradient property line), cis-
1,2-DCE and trans-1,2-DCE were detected in the sample at 84 and 1.7 µg/L, respectively; and VC
was detected at 26 µg/L. At MW-6, also located near the western property line and to the north

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
20
of well MW-30, cis-1,2-DCE and trans-1,2-DCE were detected in the groundwater sample at 34
and 8.5 µg/L, respectively; and VC was detected at 1.5 µg/L (Stantec 2022d).
Off-site locations that are monitored during semi-annual sampling events include monitoring
wells PZ-1, MW-24A, MW-25, and MW-34 which are west of the 700W Ditch. COCs have not
been detected or detected only sporadically (at trace concentrations orders of magnitude
below the MCLs), at these locations. The shallow groundwater elevations measured in
conjunction with the sampling event indicated flow toward the ditch from both the east (site)
and west sides of the ditch (Stantec 2022d).
Geochemical parameters are also analyzed during each groundwater sampling event. Recent
progress reports concluded that based on data for pH, oxidation-reduction potential (ORP),
nitrate, and ferrous iron, conditions were favorable for MNA through anaerobic reductive
dechlorination in site shallow groundwater (Stantec 2022c, 2022d).
The deeper groundwater investigation in 2016-2017 included installation of several deeper
groundwater monitoring wells near the shallow soil investigation area (near existing well MW-
34D). Deeper groundwater wells are sampled every other year, during even-numbered years.
Therefore, the eight deeper monitoring wells were last sampled during the spring of 2022.
Although trace levels of site COCs have been detected in Deeper Zone 1, COCs have not been
detected in Deeper Zones 2, 3 or 4, which are within the deeper portions of the confining unit
that separates the shallow unconfined aquifer from the deeper regional aquifer used for water
supplies.
Groundwater monitoring progress reports state that the shallow groundwater plumes are
stable at the site (see Figure A-14 in Attachment A) (Stantec 2022d). Statistical analyses
conducted by Stantec (2022d) for data collected through April 2022 indicated remaining
concentrations of the groundwater COCs (indicator chemicals established in the ROD [EPA
1991] plus VC) across the site are stable at concentrations either below or above MCLs. Results
of site groundwater monitoring have generally indicated decreasing concentrations of PCE and
TCE over time at most of the monitored locations, although at some locations (for example,
former extraction well EX-02), TCE and cis-1,2-DCE concentrations have remained relatively
consistent since 2018. The most recent progress reports reviewed for the site conclude that
based on shallow groundwater data, natural attenuation is occurring at the site and has
contributed to the reduction of PCE, TCE, cis- and trans-1,2-DCE, and 1,1-DCE concentrations
and to overall shallow groundwater plume stability. However, as shown on Figure A-15 in
Attachment A, VC concentrations have remained relatively high and consistent since the 2016-
2017 period, with concentrations in samples from former extraction well EX-11 ranging
between 260 and 510 µg/L with no consistent increasing or decreasing trend (Stantec 2022d).
In each of the three sampling locations with highest concentrations of COCs and/or degradation
products, the total CVOC concentrations (PCE, TCE, cis-1,2-DCE, trans-1,2-DCE and 1,1-DCE, and
VC) and PCP concentrations from 2016-2022 were generally as follows:
• EX-02 – total CVOCs approximately 250 – 400 µg/L; PCP detected at 1–10 µg/L;
• EX-05 – total CVOCs approximately 200 – 400 µg/L; PCP not detected; and

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
21
• EX-11 – total CVOCs approximately 175 – 1,000 µg/L; PCP not detected.
Decreases in concentrations; and thus mass, of PCE, TCE, 1,1-DCE and PCP in shallow
groundwater between 2005 and 2017 indicate that natural attenuation has occurred at the site.
However, although concentrations and mass of PCE and TCE have decreased, concentrations of
VC in some wells have not consistently exhibited a continued downward trend in recent years.
Based on this observation, the progress reports have concluded that achieving the MCL-based
goals within reasonable timeframes may not be achievable and that concentrations may have
reached asymptotic values (Stantec 2022d).

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
22
5.0 FINDINGS
Based on its review of the provided site documentation relative to these goals, the optimization
review team developed findings relative to the following specific items:
• Soil contamination;
• Extent of groundwater contamination;
• CSM;
• Progress toward remedial goals for groundwater and remedial timeframes;
• Soil vapor/VI;
• Annual remedy costs;
• Alternative remedial approaches; and
• Resource use and efficiency.
These findings are presented in the following subsections.
5.1 SOIL CONTAMINATION
The 2013 focused shallow soil investigation (Questar InfoComm 2016) confirmed the presence
of contaminants remaining in site soils at concentrations above industrial soil RSLs based on a
10-6 cancer risk HI of I noncancer risk in an industrial exposure scenario. A subsequent HHRA
indicated that no unacceptable direct contact risk existed at the site from these contaminated
soils under current site controls and industrial use scenarios. However, the concentrations of
some COCs exceeded MCL-based SSLs for soil-to-groundwater leaching, indicating a possibility
that contaminated soil may be acting as an ongoing source of contamination to groundwater.
Based on the 2013 focused shallow soil investigation, vadose zone soil contamination likely
remains in the area north and east of the former Peterson Plumbing Supply warehouse.
Furthermore, the ROD (EPA 1991) did not require soil remediation to the levels represented by
the SSLs; and only required excavation of soil to 2 ft below the water table; therefore, residual
soil contamination at concentrations that may represent a leaching concern may be present in
other areas of the site, in the vadose zone as well as in the saturated zone.
5.2 EXTENT OF SHALLOW GROUNDWATER CONTAMINATION/700 WEST DITCH
Monitoring data reviewed for the shallow groundwater monitoring network indicate that VOC
concentrations exceed the site cleanup goals in monitoring wells near the
western/downgradient site boundary. The monitoring locations west (downgradient) of the site
and the 700 West Ditch (which runs along the western site boundary) do not contain
concentrations of site COCs above MCLs. Based on the data collected to date (which includes
both contaminant concentration and piezometric data for the monitoring wells) contaminant
migration appears to be controlled either through discharge to the 700 West Ditch where COCs
move from groundwater to surface water (during gaining conditions), or head boundary, where
migration to the west is stopped by higher hydraulic head caused by the 700 West Ditch (during
losing conditions), depending on the season.

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
23
5.3 CONCEPTUAL SITE MODEL
There does not appear to be an existing CSM that includes the possibility of residual soil
contamination acting as an ongoing source to portions of the groundwater contaminant plume
and contributing to the risk of VI in site structures. Also, the potential that contamination is
migrating to and/or being controlled by hydraulic interaction between the shallow aquifer and
the 700 West Ditch does not appear to be accounted for in a comprehensive, updated CSM. For
these reasons, the site team’s estimates of the original and remaining contaminant mass,
plume stability, remedial timeframes, source locations, plume stability and viable remedial
approaches may not reflect accurate scenarios.
Soil remedial goals based on protection of groundwater were not a component of the original
soil remedy in the ROD (EPA 1991), instead soil remediation goals in the ROD, and SSLs used in
more recent evaluations, have been based on direct contact-based SSLs under an industrial use
scenario. However, achieving MCLs for site COCs in groundwater is a goal stated in the ROD
(EPA 1991), and as noted in EPA’s comments on the 2017 HHRA, COCs were still present in site
soils at concentrations that significantly exceed typical MCL-based SSLs.
Also, as previously discussed, progress reports and FYR reports reviewed indicate that the
plume is stable and not migrating off the property as significant concentrations of groundwater
COCs have not been detected in monitoring wells located off-property to the west. However,
the 700 West Ditch, which is not within the property, may be limiting the migration through
hydraulic interaction with the aquifer and acting as a discharge boundary, where COCs move
from groundwater to surface water, or head boundary, where migration to the west is stopped
by higher hydraulic head caused by the 700 West Ditch, depending on the season. Because the
potential for discharge of groundwater contamination to the ditch does not appear to have
been evaluated through sampling for COCs, it is unknown if the downgradient limit/extent of
contamination (and thus the site boundary) extend beyond the property.
5.4 REMEDIAL OBJECTIVES, TIMEFRAMES AND CONTAMINANT SOURCES
Based on groundwater flow and contaminant transport modeling completed in 2008-2009
(MWH 2009) to support the evaluation of MNA, the FFS (MWH 2010) estimated that TCE and
1,1-DCE plumes would attenuate to below MCLs in approximately 24 and 10 years, respectively.
The modeling predicted that VC would be the most persistent contaminant and remain above
its MCL for 44 years, thus controlling the overall groundwater remediation time frame for MNA.
Since that time, persistence of COCs within and at the downgradient edge of the VOC plume
indicates that while past remedial efforts (including MNA) made significant progress in reducing
contaminant mass within the groundwater plume prior to 2012, the estimated remedial
timeframes will likely not be achieved, at least for VC. The most recent progress report and 6th
FYR (EPA 2022) also indicate that additional progress toward the objective of restoring
contaminated groundwater to its potential future uses has been minimal in recent years.
As discussed in Section 5.1, estimates of remedial timeframes do not incorporate information
gathered subsequent to the RI that indicates concentrated areas of contaminant source mass
remain in shallow soils in the area north of the Peterson Plumbing Supply warehouse (EPA

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
24
2022; Stantec 2022c, 2022d). In addition, the distribution of groundwater COCs downgradient
from this area and downgradient from the former evaporation pond suggests that additional
source areas or “hot spots” in the vadose zone and within fine-grained materials in saturated
soils may remain at the site.
Shallow soil investigations completed in the vicinity of well MW-33D and the Peterson Plumbing
Supply warehouse between 2011 and 2013 indicated the presence of significant concentrations
of residual groundwater COCs and non-COCs in soil within the vadose zone. Groundwater COCs
also detected in soil samples included PCE, TCE and VC (and other CVOC degradation products).
Non-COC (BTEX) compounds detected in groundwater were also detected at relatively high
concentrations in many soil samples. Although a subsequent HHRA (MWH-Stantec 2017b)
concluded that there was no unacceptable risk, the concentrations detected and shallow
reported depth to groundwater indicate a potential that soils in this area may be acting as an
ongoing source of COCs to site groundwater. The maximum detected concentrations of VOCs in
soil are significantly above MCL-based SSLs for groundwater protection. Furthermore, the
remedial goals followed for the soil remediation completed in the 1990s were significantly
higher than leaching SSLs based on MCLs; and thus, potentially allowed leachable residual
concentrations of soil contaminants to remain around and below the excavated areas, and
within the former evaporation pond area.
The highest concentrations of total CVOCs detected in site groundwater monitoring events
have typically been detected in extraction trench EX-11, which appears to be located directly
downgradient of the former evaporation pond/ISV area. While the parent compounds PCE and
TCE are present at low concentrations, daughter products 1,2-DCE and VC have accumulated.
Daughter product persistence suggests a continuing sorbed-phase at equilibrium with CVOCs in
groundwater. Thus, shallow soil contamination (sorbed phase) in source areas (“hot spots”) is
likely contributing to the persistent groundwater contamination in the shallow aquifer. The
potential impact of additional action to accelerate degradation in such areas has not been fully
evaluated. Accordingly, it is not known how much alternative or supplemental approaches to
MNA could shorten shallow groundwater restoration timeframes.
5.5 SOIL VAPOR/VAPOR INTRUSION
While the risk of indoor air VI in structures at the site has been evaluated through four sampling
events between 2012 and 2019 and has not indicated VI-related risk exceeding
commercial/industrial exposure scenarios on-site, the potential relationship of the identified
residual soil contamination near the Peterson Plumbing Supply warehouse to VI concerns has
not been fully evaluated. Specifically, sub-slab sampling was limited to a single sample
associated with a location distant from the known shallow soil and groundwater contamination
during the 2017 sampling event. Sub-slab samples are typically collected in conjunction with
indoor air samples to provide additional context to support conclusions regarding the sources
of contamination detected in indoor air sampling and to ensure that the indoor air samples are
collected in appropriate locations.

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
25
5.6 ANNUAL REMEDY OPERATIONS, MAINTENANCE AND MONITORING COSTS
The site team provided a general estimate of typical annual operations and maintenance
(O&M) and monitoring costs. Table 4 provides a summary of the total estimated, typical annual
remediation, monitoring and reporting costs, based on current cost information provided by
the site team and the professional judgment of the optimization review team. Unit rates
included in the “Assumptions” column are estimates provided by the optimization review team.
Table 4: Estimated Annual Remediation and Monitoring Costs
Cost Category Estimated
Annual Cost Assumptions
Groundwater
Sampling Labor, Field
Costs, Laboratory
Analysis, Data
Evaluation and
Reporting
$40,000
• Based on data provided by site team and optimization
review team estimates.
• Two events annually; one event with 17 shallow wells
sampled and one event with 9 wells sampled (26 wells total
annually).
• Eight deeper wells sampled biannually; $1,000 per well,
analysis for site constituents of concern (COC) and
geochemical/monitored natural attenuation (MNA)
parameters.
• Routine data evaluation reporting.
Vapor Intrusion
Monitoring (per
event) and Reporting
$2,000
• Estimated by optimization review team.
• Assumes 10 indoor air sampling locations approximately
every 5-years proposed by site team.
Routine Property
Maintenance and
Security
$20,000 • Provided by site team.
Reimbursement of
Oversight Costs $20,000 • Provided by site team.
• Includes state and federal oversight costs.
Other Miscellaneous
Costs $100,000
• Provided by site team.
• No further information available.
• Presumed to include additional non-routine data collection,
evaluation, and reporting.
Project Management
and Reporting $100,000
• Provided by site team.
• Presumed to include routine project coordination,
management, meetings and routine groundwater
monitoring data management and reporting, and annual
reports.
TOTAL ESTIMATED
COST $282,000

MNA requires no utilities, material, or other consumable costs beyond those associated with
field team mobilization and sampling efforts for sample collection, sample shipment, laboratory
analysis, and reporting. Despite MNA being a passive technology, the reported cost data
indicate that ongoing site O&M and remedial costs are significant. Based on the information
provided by the site team, the bulk of the annual site costs appear to be associated with
Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
26
groundwater sampling and analysis, project management, detailed data evaluation and
reporting, and “miscellaneous” costs which are assumed to be for non-routine site studies and
site maintenance activities.
5.7 ALTERNATIVE REMEDIAL APPROACHES
The site team has previously evaluated alternative remedial approaches. The original remedy
included groundwater extraction and treatment, which was later amended to MNA. The FFS
(MWH 2010) evaluated several other approaches including ERH and ERD. Based on the scale
and required spacing of injection and/or heating locations, it concluded that MNA was the
preferred remedial method. However, alternative remedial approaches targeted toward source
control in more limited areas may warrant reconsideration depending on the results of the
additional source characterization recommended in Section 6.1.1.
5.8 RESOURCE USE AND EFFICIENCY
Resource use at this site is currently considered negligible. The site groundwater extraction and
treatment system has not operated since the early 2000s and there are currently no other
active remediation activities occurring at the site that require resources such as power or
water. Resource use at the site is limited to consumable sampling supplies and minimal
amounts of fuel associated with vehicles used in site sampling and maintenance activities
(semi-annual groundwater monitoring and periodic VI monitoring in site buildings). Future
resource use could potentially increase should alternative or supplemental remedial or risk
reduction activities be implemented, such as the addition of sub-slab depressurization systems
(SSDS) to mitigate potential VI in site buildings.

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
27
6.0 RECOMMENDATIONS
This section provides recommendations based on the optimization review team’s independent
review, and is organized into the following categories:
• Protectiveness;
• Cost-effectiveness;
• Technical improvement;
• Site completion; and
• Conservation of resources.
These recommendations are not enforceable and do not constitute requirements for future
action, rather they are provided for consideration by the EPA Region and other site
stakeholders. While the recommendations may provide some details to consider during
implementation, the recommendations are not meant to replace other, more comprehensive,
planning documents such as work plans, sampling plans and quality assurance project plans
(QAPP).
6.1 RECOMMENDATIONS TO IMPROVE THE REMEDY’S ABILITY TO ACHIEVE
PROTECTIVENESS GOALS
The following sections present recommendations related to achieving the protectiveness goals
established for the site.
Additional Source Area Identification and Characterization
The presence of VOC-contaminated soils in the areas north and east of the Peterson Plumbing
Supply warehouse, high concentrations of VOCs in groundwater directly downgradient from the
former evaporation pond/ISV area, and the use of industrial direct-contact or TPH-based action
levels in the ROD, suggest a potential that soil contamination may remain in parts of the site at
concentrations high enough to leach contaminants to groundwater. Based on these
considerations, the optimization review team recommends additional investigation to identify
and characterize potential source areas or “hot spots.”
The optimization review team recommends that the additional investigation consider, but not
necessarily be limited to, evaluation of soils in both the vadose and saturated zones and
shallow groundwater for concentrations of CVOCs. A recommended approach would be a high-
resolution site characterization (HRSC) effort using a vertical profiling technology such as a
membrane interface probe (MIP) to conduct continuous profiling of the subsurface for
chlorinated VOCs and hydrocarbons to the bottom of the shallow groundwater zone
(approximately 25 ft bgs). The effort would be conducted on transects across the plume
(oriented perpendicular to the apparent groundwater flow direction). Used with multiple
detectors (photoionization detector [PID], flame ionization detector [FID], and halogen specific
detector [XSD]), the MIP would provide real-time data identifying the presence and relative
concentrations of hydrocarbons and chlorinated VOCs in the soil and groundwater; however, it

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
28
would not yield analyte-specific results or concentrations. For this reason, a confirmatory
boring program is also recommended using a DPT rig to collect soil and groundwater samples
from multiple horizons within the upper/shallow aquifer at locations where the MIP data
indicate the presence of significant concentrations of VOCs in soil and/or groundwater. Soil and
groundwater sampling from multiple horizons is recommended based on the apparent
heterogeneity and interbedding of fine and relatively coarser grained materials within the
shallow aquifer. For estimating purposes, 5 samples per boring are assumed. The investigation
would include both field screening of soils for VOCs and off-site laboratory analysis of soils and
groundwater.
Costs for the MIP investigation are estimated to be approximately $85,000. This assumes use of
a DPT rig for 10 days and completion of four MIP vertical profile borings to 25 ft bgs per day, for
a total of 40 MIP profiles. Depending on the MIP field services provider, the results for each of
the three detectors may be provided in a set of 3-dimensional visualization files. Costs assume a
brief field sampling plan (and health and safety plan (HASP) update if needed), with agency
review / concurrence of proposed MIP locations; and a brief letter report with the MIP data/
logs attached.
Confirmatory soil and groundwater sampling efforts are estimated to cost approximately
$80,000; comprised of:
• $50,000 for borings at $5,000 per day for 10 days assuming that four borings would be
completed per day to a maximum depth of 25 ft bgs for a total of 40 borings.
• $30,000 for sample analyses, data tabulation and reporting based on analysis of up to
200 total samples, based on a total of 5 soil or groundwater samples collected from
each of 40 borings.
The HRSC would include a work plan, mobilization, field labor, field supplies, shipping, drilling
and analytical subcontractors, data evaluation and reporting. Based on this, the total estimated
cost for additional source area identification and characterization would be approximately
$165,000,000. This cost may or may not include a set of 3-dimensional visualization files for the
three detectors, depending on the MIP field services provider.
Data gathered by the investigation would be used to develop/support estimates of the
amounts, locations, and depths of residual contaminant source material, and to determine if
alternative or supplemental approaches to MNA may potentially decrease the estimated
remedial timeframes to achieve the remediation goal of restoring contaminated groundwater
to its potential future uses.
Additional Evaluation of the Vapor Intrusion Pathway
As discussed in Sections 4 and 5, shallow soil sampling completed in 2013 indicated relatively
high concentrations of VOCs (including groundwater COCs and additional non-COC compounds)
in site soils near the Peterson Plumbing Supply warehouse. Indoor air samples have been
collected in four events between 2012 and 2019; and contaminants were detected during
multiple events, although at concentrations that did not represent unacceptable risk. The 2022

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
29
Indoor Air Investigation report (Stantec 2022a) recommended that additional indoor air
sampling be completed at 5-year intervals. Sub-slab vapor sampling has been limited to a single
event (2017) and included only one sample location, distant from the known high
concentrations of VOCs in soils within the Peterson Plumbing Supply warehouse. TCE was
detected at 46 µg/m3 in the sample, exceeding the generic target sub-slab vapor concentration
of 15.9 µg/m3 and the indoor air VISL. Given the high concentrations of groundwater VOCs also
present in site soils adjacent to the building, the shallow water table, and potential ongoing
leaching of contaminants from the shallow soils into shallow groundwater moving beneath the
Peterson Plumbing Supply warehouse, there may be a high VI potential for this structure.
Furthermore, because there are likely VOC sources inside the building, not all indoor air
exceedances may be a result of VI. This may be further complicated by the size and
compartmentalization of the structure.
For these reasons, the optimization review team recommends collection of sub-slab vapor
samples and collocated indoor air samples during the next round of VI monitoring (presumably
no later than 2024 based on the proposed 5-year VI monitoring intervals), following a sampling
design based on the structure’s size and layout as specified in applicable guidance3. This
recommendation assumes that 10 sub-slab vapor samples be collected in conjunction with the
next planned round of indoor air sampling. This effort is estimated to cost approximately
$15,000 (maximum of $1,500 per sample), including a brief work plan, mobilization, labor and
equipment for sub-slab sampling point installation, sampling costs, laboratory analytical costs,
data evaluation, and reporting. The appropriate number and locations of sub-slab samples is
highly dependent on the layout, number, and sizes of rooms with slabs on-grade, and the
degree of compartmentalization within these structures. For these reasons, the exact number
of samples cannot be determined at this time and may be more, or less, than the assumed 10
samples. If sub-slab vapor sampling results indicate a significant potential risk, additional
monitoring and/or installation of a VIMS may be warranted to mitigate risk and maintain
protectiveness of workers in the building.
Sampling of 700W Ditch
Current assumptions regarding plume stability are based on comparison of data from the
westernmost on-property monitoring wells, and monitoring wells located off the property to
the west of the 700W ditch. However, the existing CSM, and the potentiometric surface maps
for the shallow aquifer zone, suggest that contaminants may be entering the ditch during
periods when groundwater is discharging to the 700W Ditch (gaining conditions). The
optimization review team recommends that the volume of this discharge and contaminant
concentrations be characterized when flow in the ditch is not dominated by stormwater runoff
(that is, during periods of groundwater discharge from the shallow aquifer to the ditch). This
effort would gauge hydraulic head in the ditch and site monitoring wells to confirm gaining or
losing conditions, and sample surface water in the ditch at three locations (upstream, at the
site, and downstream) on two occasions with sample analysis for CVOCs. The estimated cost for

3 EPA 2015. Technical Guide for Assessing and Mitigating the Vapor Intrusion Pathway from Subsurface Vapor Sources to Indoor
Air. https://www.epa.gov/vaporintrusion/technical-guide-assessing-and-mitigating-vapor-intrusion-pathway-subsurface-vapor

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
30
this effort (including a brief work plan, mobilization, labor, field supplies, shipping, laboratory
analysis, data evaluation and reporting) is $15,000.
6.2 RECOMMENDATIONS TO IMPROVE COST-EFFECTIVENESS
Current costs associated with site remediation are primarily limited to routine groundwater
sampling and reporting, and non-routine additional sampling, data analysis, and reporting. For
this reason, there appears to be limited potential to improve cost-effectiveness implementing
the current monitoring program unless the remedial timeframes can be reduced. This may be
possible through targeted supplemental source control; however, additional characterization
would be necessary to effectively evaluate the potential for supplemental source control to
enhance the overall cost-effectiveness by reducing the remedial timeframes (see Section 6.4).
The optimization review team recommends that the site team reduce reporting frequency (full
report with figures, tables, trends analysis) from semiannual to annual with a brief summary
memorandum for the 2nd half (9 shallow wells) sampling. This reduction in scope is estimated
to save at least $10,000 per year.
The optimization review team also recommends that project management and miscellaneous
costs be evaluated for possible further cost reduction opportunities. However, the details of
these expenses are not known so specific cost savings recommendations cannot be provided at
this time.
6.3 RECOMMENDATIONS FOR TECHNICAL IMPROVEMENT
Additional source characterization and evaluation of discharges to the 700W Ditch, would
potentially improve the accuracy of estimated timeframes to achieve remedial goals through
MNA and/or supplemental contaminant source control. Depending on the results of such
efforts it is possible that the effectiveness of the remedy may be technically improved by
implementing supplemental source control measures. These recommendations have been
discussed previously. No further specific recommendations for technical improvement of the
remedy were determined by the optimization review team.
6.4 RECOMMENDATIONS FOR SITE COMPLETION (REMEDY APPROACH MOVING
FORWARD)
The site team faces challenges similar to those at many other sites where shallow sources and
CVOC plumes are in heterogeneous (with low permeability materials) hydrogeology.
Restoration of these types of plumes and conditions has proven to require much greater
timeframes than original remedy designers typically estimated.
Updating the CSM through performance of additional investigations is recommended to
address:
• The potential that ongoing leaching of contaminants from site soils in the former
evaporation pond/ISV area, the 2013 shallow soil investigation area, or other areas
where soils containing site COCs were left in place during the original RAs, remain an
active source of COCs feeding the groundwater contaminant plume;

Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
31
• The potential off-property migration of contaminants to the 700W Ditch; and
• The potential that VI may impact on-site structures.
The persistence of COCs (including VC) in groundwater at the western property boundary
suggests that an updated CSM would better support assumptions regarding site risk, estimated
timeframes to achieve the groundwater remedial goals (MCLs) and the feasibility of reducing
those timeframes by alternative and/or supplemental remedial scenarios. It is recommended
that the CSM consider VI potential at the Peterson Plumbing Supply warehouse (addressed in
Section 6.1.2) and potential migration of contaminants to, and within, the 700W Ditch (as
discussed in Section 6.1.3).
The ongoing presence of groundwater COCs at concentrations exceeding the MCL-based action
levels may be exacerbated by the presence of residual source areas of vadose zone
contaminant mass in soils, and/or hot spots within fine-grained materials in the saturated zone.
The original remedy for soil focused on direct contact under an industrial use scenario, rather
than the potential for leaching of contamination to groundwater. The presence of known
residual soil contamination in the area north and east of the Peterson Plumbing Supply
warehouse, and the possibility of other areas of vadose and saturated zone contamination
acting as ongoing sources and/or “hot spots” could be (1) preventing further reduction of COCs
to concentrations at, or closer to, the MCL-based goals for the shallow aquifer restoration and
(2) increasing the timeframe necessary to reach restoration. Consideration of supplemental
targeted remedial activities would be highly dependent on an updated CSM addressing the
possibility that site COCs may be leaching from contaminated vadose zone soils or from “hot
spots” within the saturated zone. The need for supplemental VI-related remedial alternatives
(such as SSDS) may also be impacted by the possibility that contaminated groundwater moving
beneath or adjacent to the Peterson Plumbing Supply warehouse could result in future
unacceptable VI risk to workers in that building. However, no significant VI potential has been
determined to date, as sub-slab sampling has been limited to one sample collected in 2017.
Effectively updating the CSM to address potential residual sources would require additional site
source area characterization (as recommended in Section 6.1.1) to effectively evaluate the
need, feasibility, scale, cost, and cost effectiveness of various alternative/supplemental
remedial approaches.
The optimization review team believes that additional investigation to identify and characterize
potential source areas and/or “hot spots” in the areas where significant concentrations of VOCs
were detected in soil (in the vicinity of monitoring well MW-33D and nearby locations from the
2013 investigation and, in the vicinity of the former evaporation pond/ISV area) could
potentially identify areas that would benefit from targeted source control.
If additional source areas are identified, supplemental source control may potentially reduce
leaching of contaminants to groundwater and accelerate natural attenuation. Potential
remedial alternatives for source control could include, but are not limited, to removal and/or
in-situ shallow soil mixing with an oxidant, depending on the depth and hydrogeologic
characteristics of the zone considered for targeted treatment. Any potential additional source
Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
32
treatment would have to be conducted in a manner that is consistent with environmental
covenants/ICs that are in place for the site.
Costs for investigation actions included in this section are provided in Section 6.1. Costs for any
source removal or treatment actions that would result from the actions in Section 6.1.1 and
any additional VI related sampling or VIMS based on the actions in Section 6.1.2 cannot be
estimated at this time.
6.5 RECOMMENDATIONS FOR CONSERVATION OF RESOURCES
As previously discussed, current resource use at this site appears to be minimal. The
optimization review team has no specific recommendations at this time for conservation of
resources.
6.6 ESTIMATED COSTS AND SAVINGS
Table 5 summarizes estimated costs and potential savings associations with the optimization
review team’s recommendations. Note that because the potential effectiveness and scale of
supplemental or alternative source control measures cannot be determined until additional
source characterization is conducted, specific recommendations and costs for these activities
are not included.
Table 5: Summary of Estimated Costs and Savings
Recommendation(s) # Sub-Recommendation Estimated
Costs
Estimated
Savings
6.1 - Recommendations to
Improve the Remedy’s
Ability to Achieve
Protectiveness Goals
6.1.1 Additional Source Area
Identification and Characterization $165,000 Unknown
6.1.2 Additional Evaluation of the Vapor
Intrusion Pathway $15,000 None
6.1.3 Sampling / Evaluation of Discharge;
700 W. Ditch $15,000 None
6.2 - Recommendations to Improve
Cost-Effectiveness
Reduction of Groundwater
Reporting None $10,000
per year
6.3 - Recommendations for
Technical Improvement
Contingent on outcome of
Recommendation 6.1.1 Not Estimated
6.4 - Recommendations for Site
Completion (Remedy Approach
Moving Forward)
Contingent on outcome of
Recommendation 6.1.1 Not Estimated
Notes: NA = not applicable
Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
ATTACHMENT A :
Selected Figures from Site Documents
Figure 1: Site Vicinity Map
Figure A-1: Site Location Map
3
Source: Figure 1. Site Vicinity Map From U.S. Environmental Protection Agency, 2022. Sixth Five-Year Review Report for Wasatch Chemical Co.
(Lot 6) Superfund Site, Salt Lake County, Utah. August.
Figure 2: Institutional Control Map
9
Source: Figure 2. Institutional Control Map From U.S. Environmental Protection Agency, 2022. Sixth Five-Year Review Report for Wasatch
Chemical Co. (Lot 6) Superfund Site, Salt Lake County, Utah. August.
Figure A-2: Site Property and Institutional Controls
,"'-,
EXPLANATION
� Shallow monitoring well
(lo 25 feet bgs)
B Shallow extraction trench
discharge sump
(lo 25 feet bgs)
� Shallow extraction well
(lo 25 feet bgs)
V Shallow piezometer
(lo 25 feet bgs)
@ Deeper monitoring well
Zone 1 (45 to 56 feet bgs)
-$-Deeper monitoring well
Zone 2 (88 to 91 feet bgs) .. Deeper monitoring well
Zone 3 (128 feet bgs)
♦Deeper monitoring well
Zone 4 (157.8 feet bgs)
0 Shallow monitoring points
sampled April and May
2022
0 Deeper monitoring points
sampled April and May
2022
D Buildings included in the
2012-2019 indoor air
sampling program
2013 deeper groundwater
and shallow soil focused
investigation area
Area of shallow soils with
concentrations above
� USEPA regional screening
levels (for target cancer
risk of 1 x10·5 and hazard
index of 1)
bgs Below ground surface
OUEST�R lnfoComm
Figure A-3: Groundwater Monitoring Network
Source: Figure 1. April and May 2022 Groundwater Monitoring Network and 2013 Focused Investigation Area From Stantec, 2022d. Wasatch Chemical Site
Progress Report No. 117. October.
0 50 100
Feet
AA
A'A'
EX 07
PZ 5
EX 01 ES 01DP-CPT-012
DP-CPT-007
DP-CPT-013
DP-CPT-010
DP-CPT-008 DP-CPT-009
DP-CPT-005DP-CPT-003
DP-CPT-002MW-39D4
DP-CPT-001
DP-CPT-004
MW 35D2
MW 36D2
DP-CPT-011
MW 33D
EX 07
PZ 5
EX 01 ES 01DP-CPT-012
DP-CPT-007
DP-CPT-013
DP-CPT-010
DP-CPT-008 DP-CPT-009
DP-CPT-005DP-CPT-003
DP-CPT-002MW-39D4
DP-CPT-001
DP-CPT-004
MW 35D2
MW 36D2
DP-CPT-011
MW 33D
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
170
0
A A'
MW
-
3
5
D
2
DP
-
C
P
T
-
0
1
2
226'
DP
-
C
P
T
-
0
1
3
DP
-
C
P
T
-
0
1
1
MW
-
3
9
D
4
DP
-
C
P
T
-
0
0
2
MW
-
3
3
D
DP
-
C
P
T
-
0
0
7
?
?
?
?
?
Shallow Groundwater Zone
Deeper Groundwater Zone 1
Deeper Groundwater Zone 2
Deeper Groundwater
Zone 3
Deeper Groundwater
Zone 4
0
0
20
25
Horizontal Scale in Feet
VERTICAL EXAGGERATION .8 TIMES
WASATCH CHEMICAL SITE
SOIL/SEDIMENT CLASSIFICATION
CROSS SECTION A-A'
Figure 2
C:
\
D
a
t
a
\
M
W
H
\
Q
u
e
s
t
a
r
\
W
a
s
a
t
c
h

C
h
e
m
i
c
a
l
\
P
R
O
G
R
E
S
S

R
E
P
O
R
T
_
N
o
1
0
8
\
F
I
G
U
R
E
S
\
F
i
g

2
_
S
o
i
l
_
S
e
d

C
l
a
s
s
i
f
i
c
a
t
i
o
n

C
r
o
s
s

S
e
c

A
_
A
_
1
8
J
a
n
2
0
1
8
.
a
i
18

J
a
n

2
0
1
8
DR
A
W
N

B
Y

D
.

S
e
v
e
r
s
o
n
Sand
Silt
Clay/sensitive fines
Interbedded sand
Interbedded silt
Interbedded clay/sensitive fines
Interbedded silt/clay
Interbedded clay/silt
Fine sand/sand
Interbedded silt/fine sand/clay
Screened interval
Figure A-4: Cross Section Soil/Sediment Classification Cross Section A-A’
Source: Figure 2. Solid/Sediment Classification Cross Section A-A' From Stantec, 2022d. Wasatch Chemical Site Progress Report No. 117. October.
,
EXPLANATION
♦Shallow monitoring well
(to 25 feet bgs)
Shallow extraction trenchB discharge sump
(to 25 feet bgs)
� Shallow extraction well
(to 25 feet bgs)
V Shallow piezometer
(to 25 feet bgs)
� Deeper monitoring well
Zone 1 (45 to 56 feet bgs)
-$-Deeper monitoring well
Zone 2 (88 to 91 feet bgs)... Deeper monitoring well
Zone 3 (128 feet bgs)
♦Deeper monitoring well
Zone 4 (157.8 feet bgs)
��-Groundwater contours
0,'J.i (dashed where inferred)
(4226.20) Groundwater level elevation
(feet above mean sea level)
bgs Below ground surface
NA Not Available
1) Shallow monitoring wells, piezo­meters, extraction wells, andtrenches are less than 25 feetdeep.
2) Groundwater levels measured on April 25, 2022 for all locations except ES 01which was measured on April 26, 2022. All locations were measured prior to groundwater sampling.
3)700 West Ditch surface water elevationwas measured on April 25, 2022.
OUEST.I.R lnfoComm
WASATCH CHEMICAL SITE
SHALLOW GROUNDWATER
ELEVATIONS
April 2022
Figure 3
Figure A-5: Shallow Groundwater Elevations – April 2022
Source: Figure 3. Shallow Groundwater Elevations April 2022 From Stantec, 2022d. Wasatch Chemical Site Progress Report No. 117. October.
EXPLANATION
♦ Shallow monitoring well
(lo 25 feet bgs)
B Shallow extraction trench
discharge sump
(to 25 feet bgs)
� Shallow extraction well
(to 25 feet bgs)
V Shallow piezometer
(to 25 feet bgs)
@ Deeper monitoring well .Zone 1 (45 to 56 feet bgs)
-t Deeper monitoring well
Zone 2 (88 to 91 feet bgs)
.... Deeper monitoring well
Zone 3 (128 feet bgs)
♦Deeper monitoring well
Zone 4 (157.8 feet bgs)
"',,,. Groundwater contours ,.,1,1 ., bi.. ( dashed where inferred)
r4227_67) Groundwater level elevation
(feet above mean sea level)
bgs Below ground surface
NOTES:
1) Groundwater level data collected
April 25, 2022 prior to
groundwater sampling.
2)Zone 1 deeper wells are
completed to depths between
48 and 56 feet bgs.
3)Contours based on groundwater level
elevations measured in wells
MW 31 D, MW 320, and MW 330
screened 38-48, 46-56, and 35-45
feet bgs, respectively.
OUESTPR
lnfoComm
WASATCH CHEMICAL SITE
GROUNDWATER ELEVATIONS
FOR ZONE 1 DEEPER WELLS
April 2022
Figure 4
Figure A-6: Deeper Zone 1 Groundwater Elevations – April 2022
Source: Figure 4. Groundwater Elevations For Zone 1 Deeper Wells April 2022 From Stantec, 2022d. Wasatch Chemical Site Progress Report No. 117. October.
I---------------------------------------------------------------
EXPLANATION
*Shallow monitoring well
location
(V
1
Deeper monitoring well
location
H Extraction trench
discharge sump location
H Shallow extraction well
location
i V Shallow piezometer
location
□Buildings of potential
Deeper groundwater and
shallow soil investigation
area
m Area of shallow soils with
concentrations above
USEPA regional screening
levels (for target cancer
risk of 1x10-6 and hazard
index of 1)
Grayed symbols denote locations
used for shallow groundwater
level monitoring only
Groundwater
Treatment
System
Building
i
:
i
■
>.exo2'-
HgSa—%■ 1 ' %Z5V ■
I!1—' mMS
I * 1
*8 1
-"
SHALLOW
SOILS ABOVE
USEPA
SCREENING
LEVELS
JF.
-vh
1
2 i
■£&« ill
s
EX 01
MW 33D, \
FOCUSED
INVESTIGATION
AREA
' ‘tt1...' :>■A ■
EX 08 J ?
‘ =4liJ|A j
f.■?*.-I ]
a--’ :
*§ ■ ■-*
MW 234--
\
■te
^ || f* '
5 " •.If «■ -(f ’*r. * * *
h W* _ i ' ■«
i_.___________________________*-..i
M W**•tr f*
%s ■
Er'-;' r" ’■
\a| r< >■
2100 South Street
Stantec Fict
0 250
__________
Quest* n
InfoComm
WASATCH CHEMICAL. SITE
SITE MAP AND FOCUSED SHALLOW
SOIL INVESTIGATION AREA
Figure 1
Figure A-7: Focused Shallow Soil Investigation Area – May 2013
______________________
Source: Figure 1. Site Map And Focused Shallow Soil Investigation Area From MWH-Stantec. 2017. Human Health Risk Assessment for Shallow Soils in the
Focused Investigation Area at the Wasatch Chemical Site, Salt Lake City, Utah. August 28.
FILE: C:\Data\MWH\Questar\Wasatch Chemical\Human Health Risk Assessment\FIGURES\Fig 2_Focused Shallow Soil Invest Boring Locs and Results_21Apr2017.mxd 21 Apr 2017 DRAWN BY D. Severson
WASATCH CHEMICAL SITE
MAY 2013 FOCUSED SHALLOW SOIL
INVESTIGATION BORING LOCATIONS AND
RESULTS RELATIVE TO SCREENING LEVELS
Figure 2
Figure A-8: Focused Shallow Soil Investigation Boring Locations and Results Relative to Screening Levels – May 2013
Source: Figure 2. May 2013 Focused Shallow Soil Investigation Boring Locations and Results Relative to Screening Levels From ource: Figure 1. Site Map And Focused Shallow Soil Investigation Area
From MWH-Stantec. 2017. Human Health Risk Assessment for Shallow Soils in the Focused Investigation Area at the Wasatch Chemical Site, Salt Lake City, Utah. August 28.
" 0 £ (li].ffl) Tetrachloroethene::, <( concentration (µg/1)
"'� Monitoring well location "'0
� Extraction trench c,; B 1 discharge sump location ., Cl � Extraction well location
1:; V Piezometer location a. ., r-.: t: µg/1 Micrograms per liter 0 a. "a:: "MCL Maximum contaminant level "� 0, � PCE Tetrachloroethene ,:: t: NOTES: 0 a. " 1)Samples collected April 26 througha:: "" May 3, 2022.� 0, � 2) lsoconcentration contours are not 0 shown because PCE was nota:: 0.. detected above its MCL of 5 µg/I.,::I
<o ::': 3) 0 0 "' "'S,l :::;
: @ --1!I .. I I =t I E'X09
(!:3MD �
OUEST�R lnfoComm
WASATCH CHEMICAL SITE
TETRACHLOROETHENE DETECTED IN
SHALLOW GROUNDWATER
April and May 2022
Figure 5
Figure A-9: Tetrachloroethene Detected in Shallow Groundwater – April and May 2022
Source: Figure 5. TetraChloroethene Detected in Shallow Groundwater April and May 2022 From Stantec, 2022d. Wasatch Chemical Site Progress Report No. 117. October.
� Trichloroethene \ concentration contour (µg/1)
(dashed where inferred)
(25)Trichloroethene" concentration (µg/1)0 £ ::, <( � Monitoring well location
"'Extraction trench "'B 0 discharge sump location � c,; 1 � Extraction well location ., Cl
V Piezometer location
1:; "-µg/1 Micrograms per liter ., r-.: t: MCL Maximum contaminant level 0 "-"a:: " T Trace concentration " � 0, � TCE Trichloroethene ,:: t: 0 NOTES: "-" a:: " 1) Samples collected April 26 through " �May 3, 2022. 0, � 2) lsoconcentration contours are shown0 a:: for concentrations above the TCE0.. ,::I MCL of5 µg/1. <o ::': 0 3) 0 "'"'S,l :::;
: @ --1 ! I.. I I =t I E�09
(0.�1 T)�
OUEST�R lnfoComm
WASATCH CHEMICAL SITE
TRICHLOROETHENE DETECTED IN
SHALLOW GROUNDWATER
April and May, 2022
Figure 6
Figure A-10: Trichloroethene Detected in Shallow Groundwater – April and May 2022
Source: Figure 6. TetraChloroethene Detected in Shallow Groundwater April and May 2022 From Stantec, 2022d. Wasatch Chemical Site Progress Report No. 117. October.
Vitrified
Soil
Intsel Steel West
Office
Groundwater Treatment
System Building
SITE
BOUNDARY
Peterson
Plumbing Supply
MW 33D
MW 35D2
MW 36D2
MW 37D2
MW 39D4 MW 38D3
(<1.0)
MW 25
2100 South Street
Intsel Steel West
Warehouse
PZ 5
PZ 04
MW 22
EX 01
WP 02
MW 21
MW 32D
MW 31D
MW 02
PZ 3
PZ 1
MW 34
MW 30
MW 23
MW 20
MW 06
EX 11
EX 09
EX 08
EX 07
EX 05
EX 04
EX 02
ES 01
MW 24A
(1.4)
(4.5)
(6.4)
(4.7)
(3.0)
(3.3)
(<1.0)
(<1.0)
(<1.0)(<1.0)
(<1.0)
(<1.0)
(1.2)
(0.13 T)
(0.84 T)
(0.12 T)
0 250
Feet
WASATCH CHEMICAL SITE
1,1-DICHLOROETHENE DETECTED IN
SHALLOW GROUNDWATER
Figure 7
April and May 2022
1,1-Dichloroethene
concentration (µg/l)
Monitoring well location
Extraction trench
discharge sump location
Extraction well location
Piezometer location
EXPLANATION
NOTES:
Samples collected April 26 through
May 3, 2022.
Isoconcentration contours are not
shown because 1,1-DCE was not
detected above its MCL of 7µg/l.
Grayed symbols are locations not
included in monitoring network.
1)
2)
3)
(14)
µg/l
1,1-DCE
MCL
T
Micrograms per liter
1,1-Dichloroethene
Maximum contaminant level
Trace concentration
KEPCO+
Office
Figure A-11: 1,1-Dichloroethene Detected in Shallow Groundwater – April and May 2022
Source: Figure 7. 1, 1-Dichloroethene Detected in Shallow Groundwater April and May 2022 From Stantec, 2022d. Wasatch Chemical Site Progress Report No. 117. October.
� Vinyl chloride
\ concentration contour (µg/1)
(dashed where inferred)
(6.5) Vinyl chloride
concentration (µg/1)
� Monitoring well location
B Extraction trench " discharge sump location 0 £ ::, <( � Extraction well location
"'"'V Piezometer location 0
� c,; µg/1 Micrograms per liter 1., Cl D Sample diluted
1:; J-Value estimated, biased lowa. ., r-.: t: MCL Maximum contaminant level 0 a. " a:: T Trace concentration " "� 0, 0 cl: vc Vinyl chloride
,:: t: NOTES: 0 a. � 1)Samples collected April 26 through:;J � May 3, 2022.l 2) lsoconcentration contours are shown 0 a:: for concentrations above the VG0.. ,::I MCL of 2 µgit.
<o ::': 3)Grayed symbols are locations not 0 0 included in monitoring network. "'"'S,l :::;
OUEST�R lnfoComm
WASATCH CHEMICAL SITE
VINYL CHLORIDE DETECTED IN
SHALLOW GROUNDWATER
April and May 2022
Figure 8
Figure A-12: Vinyl Chloride Detected in Shallow Groundwater – April and May 2022
Source: Figure 8. Vinyl Chloride Detected in Shallow Groundwater April and May 2022 From Stantec, 2022d. Wasatch Chemical Site Progress Report No. 117. October.
Vitrified
Soil
Intsel Steel West
Office
Groundwater Treatment
System Building
SITE
BOUNDARY
Peterson
Plumbing Supply
MW 30
MW 33D
MW 35D2
MW 36D2
MW 37D2
MW 39D4 MW 38D3
1.0
2100 South Street
Intsel Steel West
Warehouse
PZ 5
PZ 1
PZ 3
EX 11
(<0.50)
MW 20
PZ 04
MW 22
MW 23
EX 01
EX 08
(0.14 T)
WP 02
EX 02
(8.3 D)
EX 07
(<0.50)
EX 04
MW 21
EX 05
EX 09
MW 06
MW 24A
MW 32D
MW 31D
ES 01
(<0.50)
MW 02
MW 25
MW 34
0 250
Feet
WASATCH CHEMICAL SITE
PENTACHLOROPHENOL DETECTED IN
SHALLOW GROUNDWATER
Figure 9
April and May 2022
NOTES:
Samples collected April 26-28, 2022.
Isoconcentration contours are shown
for concentrations above the PCP
MCL of 1 µg/l.
Grayed symbols are locations not
included in monitoring network.
1)
2)
3)
KEPCO+
Office
EXPLANATION
Pentachlorophenol
concentration contour (µg/l)
(dashed where inferred)
Pentachlorophenol
concentration (µg/l)
Monitoring well location
Extraction trench
discharge sump location
Extraction well location
Piezometer location
µg/l
D
J+
MCL
PCP
T
(<0.5)
Micrograms per liter
Sample diluted
Data are estimated due to
associated quality control data
Maximum contaminant level
Pentachlorophenol
Trace concentration
Figure A-13: Pentachlorophenol Detected in Shallow Groundwater – April and May 2022
Source: Figure 9. Pentachlorophenol Detected in Shallow Groundwater April and May 2022 From Stantec, 2022d. Wasatch Chemical Site Progress Report No. 117. October.
Vitrified
Soil
MW 06
MW 35D2
MW 36D2
MW 38D3 MW 39D4
MW 37D2
2100 South Street
PZ 5
PZ 1
PZ 3
EX 11
MW 20
PZ 04
MW 22
MW 23
EX 01
WP 02
EX 02
EX 07
MW 25
MW 14
EX 04
MW 21
EX 05
EX 09
MW 30
MW 33D
MW 24A
MW 32D
MW 31D
ES 01
MW 34
MW 02
EX 08
EXPLANATION
Shallow monitoring well
Shallow extraction trench
discharge sump
Shallow extraction well
Shallow piezometer
Deeper monitoring well
WASATCH CHEMICAL SITE
SHALLOW GROUNDWATER
STABILITY EVALUATION RESULTS
FOR MONITORING LOCATIONS WITH
COCs STATISTICALLY ABOVE MCLs
April and May 2022
Figure 10
µg/l
COC
ID
MCL
PCE
1,1-DCE
PCP
VC
0 250
Feet
EX 11
VC
MW 20
VC
EX 02
TCE
VC
PCP
MW 30
VC
SITE
BOUNDARY
Micrograms per liter
Constituent of concern
Identification
Maximum contaminant level
Tetrachloroethene
1-1-Dichloroethene
Pentachlorophenol
Vinyl chloride
Statistically above MCL with
no trend(b)
TCE shallow groundwater
plume MCL (5 µg/l) footprint(a)
VC shallow groundwater
plume MCL (2 µg/l) footprint(a)
PCP shallow groundwater
plume MCL (1 µg/l) footprint(a)
Plume footprints were drawn based on
April/May 2022 data.
The eight most recent data points
were used to evaluate statistically
significant COC concentrations.
Stability evaluation results are shown
only for those data sets that were
deemed statistically above the MCL.
NOTES:
(a)
(b)
WELL ID
STABLE
VC
EX 05
1,1-DCE
Figure A-14: Shallow Groundwater Stability Evaluation Results
Source: Figure 10. Shallow Groundwater Stability Evaluation Results For Monitoring Locations With COCs Statistically Above MCLs April and May 2022 From U.S.
Environmental Protection Agency, 2022. Sixth Five-Year Review Report for Wasatch Chemical Co. (Lot 6) Superfund Site, Salt Lake County, Utah. August.
2 0 _Tre.!!d '!!_ 99�: � _ · Slope: 0
1.5-
1.0-
0.5-
VinylChloride(µg/1) - EX-08 VinylChloride(µg/1) - EX-09
1.5-
1.0-
0.5-
-------•
0.0-, 0--0-0 - - --0--o- - - -o 0.0-- --o-
2016
800-
600-
400-•• ---
200-•
O _Tre.!!d '!!_ 99�: � _
Slope: 30.77
I 2016
I I I I I I 2018 2020 2022 2016 2018 2020
VinylChloride(µg/1) -EX-11 VinylChloride(µg/1) - MW-06
------
I 2018
•
-­... ----
I 2020
• ----• --
I 2022
2 O _Tre.!!d '!!_ 99�: � _ · Slope: 0.1671
1.5-
• 1.0---. ---.--------
0.5-
0.0-
I I 2019 2020
Date
•
0 Non-Detect at 1/2 Method Detection Limit (MDL) Best-Fit Line and 99% Confidence Band - · MCL
I 2021
I 2022
• • -------
I 2022
Figure A-15: Vinyl Chloride Concentration Trends at Select Wells – 2016-2022
Source: Vinyl Chloride Concentration Trends at Select Wells, 2016-2022 From Stantec, 2022d. Wasatch Chemical Site Progress Report No. 117. October.
Wasatch Chemical Co. (Lot 6) Superfund Site Final Optimization Review Technical Memorandum
Salt Lake City, Utah EPA Region 5 START V Contract: Document Tracking Number 1631c
ATTACHMENT B :
Selected Tables from Site Documents
Table B-1. Soil and Sludge Indicator COCs and Action Levels
Table 1: Soil and Sludge Indicator COCs and Action Levels
Source: Table 1. Soil and Sludge Indicator COCs and Action Levels From US EPA. Draft Sixth Five-Year Review Report
for Wasatch Chemical Co. (Lot 6) Superfund Site, Lake County, Utah.
Soil and Sludge
COC
ROD Action
Levela (µg/kg)
Trichloroethylene (TCE) 103,000
Tetrachloroethylene (PCE) 22,000
Hexachlorobenzene 7,000
4,4-Dichlorodiphenyldichloroethane (DDD) 26,000
4,4-Dichlorodiphenyldichloroethylene (DDE) 19,000
4,4-Dichlorodiphenyltrichloroethane (DDT) 19,000
Alpha-chlordane 7,000
Gamma-chlordane 7,000
Heptachlor 2,000
Tetrachlorodibenzo-p-dioxin (TCDD) (total) 20
Notes:
Source: Table 5.2 of the 1991 ROD (pdf page 23).
a. Action levels are health-based for industrial use (1991 ROD pdf
page 5).
µg/kg = micrograms per kilogram
Table B-2. Groundwater COC Action Levels
Table 2: Groundwater COC Action Levels
Groundwater
COC
ROD Action
Levela (μg/L)
VOCs
PCE 5
TCE 5
1,1-Dichloroethylene (1,1-DCE) 7
SVOCs
Pentachlorophenol (PCP) 1
Herbicides and Pesticides
2,4-Dichlorophenoxyacetic acid (2,4-D) 70
Notes:
Source: Table 5.4 of the 1991 ROD.
a. Action levels are based on drinking water regulations under the
Safe Drinking Water Act, MCLs.
μg/L = micrograms per liter
Source: Table 2. Groundwater COC Action Levels From US EPA. Draft Sixth Five-Year Review Report for
Wasatch Chemical Co. (Lot 6) Superfund Site, Lake County, Utah.
TABLE A-l
FOCUSED SHALLOW SOIL INVESTIGATION ANALYTICAL RESULTS - MAY 2013
WASATCH CHEMICAL SITE, SALT LAKE CITY, UTAH
(Page I of 4)
Location Identification MW-33D(h)DPSS-01 DPSS-01 DPSS-02 DPSS-02 DPSS-03
Field Sample Identification MW-33D-3.5 DPSS-01-1.7 DPSS-01-3.2 DPSS-02-3.4 DPSS-02-4.9 DPSS-03-1
Date Collected 10/12/2011 5/6/2013 5/6/2013 5/6/2013 5/6/2013 5/6/2013
Sample Depth (ft)3.5 1.7 3.2 3.4 4.9 1.1
Depth to Saturated Zone (ft)4.0 2.0 2.0 2.0 2.0 2.3
Maximum Depth of Recovered Soil<d) (ft)3.4 3.4 5.0 5.0 5.0 5.0
Industrial Soil
Screening levels,a>
(»gAg)
DPSS-03 DPSS-04 DPSS-04 DPSS-05 DPSS-05 DPSS-06 DPSS-06 DPSS-07 DPSS-08
DPSS-03-3.4 DPSS-04-3.4 DPSS-04-4.9 DPSS-05-1.1 DPSS-05-2.1 DPSS-06-3.4 DPSS-06-5.0 DPSS-07-2.2 DPSS-08-2.
5/6/2013 5/6/2013 5/6/2013 5/6/2013 5/6/2013 5/6/2013 5/6/2013 5/6/2013 5/6/2013
3.4 3.4 4.9 1.1 2.1 3.1 5.0 2.2 2.4
2.3 3.2 3.2 2.2 2.2 2.2 2.2 >3.0 2.3
5.0 5.0 5.0 3.5 3.5 5.0 5.0 3.0 2.5
DPSS-09 DPSS-10 DPSS-11 DPSS-11 DPSS-12 DPSS-12 DPSS-13 DPSS-13 DPSS-14
DPSS-09-2.0 DPSS-10-2.2 DPSS-11-0.5 DPSS-11-1.9 DPSS-12-1.0 DPSS-12-2.0 DPSS-13-1.0 DPSS-13-2.9 DPSS-14-1.0
5/6/2013 5/6/2013 5/6/2013 5/6/2013 5/6/2013 5/6/2013 5/6/2013 5/6/2013 5/6/2013
2.0 2.2 0.5 1.9 1.0 2.0 1.0 2.9 1.0
>2.0 >2.5 2.0 2.0 1.4 1.4 2.8 2.8 2.8
2.5 2.5 2.0 2.0 3.3 3.3 3.0 3.0 3.0
Photo-ionization Detector Reading (ppm)
Volatile Organic Compounds (pg/kg)
1.1.1 -T richloroethane
1.1 -Dichloroethane
1,1 -Dichloroethene
1.2.4- Tnmethylbenzene
1,2-Dichloroethane
1.3.5- Trimethylbenzene (Mesitylene)
2-Chlorotoluene
Acetone
Benzene
Carbon disulfide
Chloroethane
Chloroform
c is-1,2-Dichloroethene
Ethylbenzene
Isopropylbenzene (Cumene)
Methyl ethyl ketone (2-Butanone)
Methylene chloride
n-Propylbenzene
Naphthalene
m,p-Xylene (Sum of isomers)
o-Xylene (1,2-Dimethylbenzene)
Total Xylene (Sum of all 3 isomers/0
Tetrachloroethene (PCE)
Toluene
Trichloroethene (TCE)
Vinyl chloride
Herbicides (pg/kg)
2,4 DB
2.4.5- T (Trichlorophenoxyacetic acid)
2,4-D (Dichlorophenoxyacetic acid)
Dalapon
Dicamba
Dichloroprop
Dinoseb
Pentachlorophenol
Silvex (2,4,5-TP)
NA 15,000 0 605 0 18 0 0 168 128 0 4
36.000,000 4,000 TD <6.60 <1,200 D <6.60 <5.50 <4.60 <6.10 4.2 T <120,000 D <4.20 <7.40
16,000 <6,400 D <6 60 <1,200 D <6.60 <5 50 <4.60 16 <6.40 <120,000 D <4 20 <7.40
1,000.000 <6,400 D <6.60 <1,200D <6.60 <5.50 <4 60 <6 10 <6.40 <120,000 D <4.20 <7.40
240.000 na <6.60 620 TD <6 60 <5.50 <4.60 2 T <6.40 <120,000 D <4.20 <7 40
2,000 <6,400 D <6.60 <1,200 D <6.60 <5.50 <4.60 <6.10 <6.40 <120,000 D <4.20 <7.40
12.000,000 na <6 60 1,300 D <6.60 <5.50 <4.60 2.3 T <6.40 <120,000 D <4 20 <7.40
23.000,000 na <6.60 <1,200 D <6 60 <5.50 <4.60
<6.10 <6.40 <120,000 D <4.20 <7.40
670,000,000 13,000 2.2 TUB <1,200 DUJ <6.60 UJ <5.50 7.1 UB 70 UB <6.40 <120,000 DUJ <4.20 UJ 3.2 TUBJ
5.100 <6,400 D <6.60 <1,200 D <6.60 <5.50 <4.60 <6.10 <6.40 <120,000 D <4.20 <7.40
3,500,000 6,400 2.7 T <1,200 D <6.60 2.3 T <4.60 1.9 T <6.40 <120,000 D <4.20 <7.40
NE <6,400 D <6.60 <1,200 D <6.60 <5.50 <4 60 <6.10 <6.40 <120,000 D <4.20 <7.40
1,400 <6,400 D <6.60 <1,200 D <6 60 <5.50 <4 60 <6.10 <6.40 <120,000 D <4.20 <7 40
2,300.000 37,000 D 39 <1,200 D 40 5.1 T <4.60 <6.10 <6.40
<120,000 D <4.20 <7 40
25,000 1,400,000 D <6.60 8,400 D <6.60 14 <4 60 14 <6.40 110,000 TD <4.20 <7.40
9,900,000 na <6.60 4300 D <6.60 <5.50 <4.60 3.2 T <6.40 <120,000 D <4.20 <7.40
190,000.000 <13,000 D <6.60 <1,200 D <6.60 <5.50 <4 60 17 <6.40 <120,000 D <4.20 <7.40
1.000.000 <6,400 D <6.60 <1,200 D <6.60 <5.50 <4.60 <6.10 <6.40
<120,000 D <4.20 <7.40
NE na <6.60 3,400 D <6.60 <5.50 <4.60 2 T <6.40 <120,000 D <4.20 <7.40
17,000 <6,400 D <6.60 410 TD <6.60 <5 50 <4.60 <6 10 <6.40 <120,000 D <4.20 <7.40
NE 12,000,000 D <13 49,000 D 2.6 T 210 1.9 T 24 5.6 T 940,000 D <8.40 23 T
2.800,000 4,000,000 D <6.60 22,000 D <6.60 85 <4.60 58 2.1 T 360,000 D <4.20 <7 40
2,500.000 16,000,000 0 71,000 2.6 295 1.9 82 7.7 1,300,000 nc 2.3
100,000 3,100,000 D 7.1 610 TD 220 26 5.3 <6.10 87 <120,000 D 21 <7.40
47,000,000 610,000 D <6 60 <1,200 D <6.60 3.8 T <4.60 11 <6,40 47,000 TD <4.20 <7.40
6.000 78,000 D 4 T <1,200 D 14 <5.50 <4.60 2 T 35 <120,000 D 2.8 T <7.40
1,700 <6,400 D <6.60 <1,200 D <6 60 <5.50 <4 60 <6.10 <6.40 <120,000 D <4.20 <7.40
6,600.000 na <43 <43 UJ 1ST <35 <41 <41 <44 <45 11 TJ <36
8.200.000 na <8.70 <8 70 UJ <8.40 <7.10 <8 40 <8.30 <8 90 52 J <7.70 UJ <7.30
9,700.000 na <43 <43 UJ <42 <35 <41 <41 <44 <45 UJ <38 UJ <36
25,000,000 na 390 J 61 J 49 110 45 50 130 52 J 19 TJ 19 T
25,000,000 na <8.70 <8 70 UJ <8.40 <7.10 <8.40 <8.30 <8.90 <9.10 <7.70 UJ <7.30
NE na <43 <43 UJ <42 <35 <41 <41 <44 <45 <38 UJ <36
820,000 na <8.70 UJ <8.70 UJ <8 40 <7.10 <8 40 8.2 T <8 90 <9.10 7.9 J <7.30
4,000 1,200 <4 30 UJ 6.2 J <4.20 <3 50 14 <4.10 <4.40 <4.50 13 J <3.60
6,600,000 na <8.70 <8.70 UJ <8.40 <7.10 <8.40 <8.30 <8.90 <9.10 <7.70 UJ <7.30
0 158 na 100 4,141 159 na na 0 0 0 18 5
<5.60 <56,000 D <5.20 63,000 D <75,000 D <9,700 D <500 D 34 52 <9.80 <7.50 <460 D <4.60
<5 60 <56,000 D <5.20 <49,000 D <75,000 D <9,700 D <500 D 9.2 16 T <9.80 <7.50 <460 D <4 60
<5.60 <56,000 D <5.20 <49,000 D <75,000 D <9,700 D <500 DUJ <6 <17 <9.80 <7.50 <460 DUJ <4 60
<5.60 <56,000 D <5.20 <49,000 D <75,000 D <9,700 D <500 D <6 <17 <9.80 <7.50 <460 D <4.60
<5 60 <56,000 D <5.20 <49,000 D <75,000 D <9,700 D <500 D 2.9 T 16 T <9.80 <7.50 <460 D <4.60
<5 60 <56,000 D <5.20 <49,000 D <75,000 D <9,700 D <500 D <6 <17 <9 80 <7.50 <460 D <4 60
<560 <56,000 D <5.20 <49,000 D <75,000 D <9,700 D <500 D <6 <17 <9.80 <7.50 <460 D <4 60
<5.60 UJ <56,000 DUJ <5.20 <49,000 DUJ <75,000 DUJ <9,700 DUJ 2,800 DUBJ <6 UJ 40 UB 21 UB 2.5 TUB <460 DUJ 1.9 TUB
<5.60 <56,000 D <5.20 <49,000 D <75,000 D <9,700 D <500 D <6 <17 <9.80 <7.50 <460 D <4 60
<5 60 <56,000 D <5.20 <49,000 D <75,000 D <9,700 D <500 DUJ <6 <17 <9.80 <7.50 <460 DUJ <4 60
<5.60 <56,000 D <5.20 <49,000 D <75,000 D <9,700 D <500 DUJ <6 <17 <9.80 <7.50 <460 DUJ <4.60
<5.60 <56,000 D <5.20 <49,000 D <75,000 D <9,700 D <500 D <6 <17 <9.80 <7.50 <460 D <4.60
<5.60 <56,000 D <5.20 <49,000 D <75,000 D <9,700 D <500 D <6 <17 <9.80 <7.50 <460 D <4.60
<5.60 41,000 TD 2.1 T 270,000 D 520,000 D 85,000 D 490 TD 2.3 T <17 <9.80 <7.50 520 D <4.60
<5 60 <56,000 D <5.20 22,000 TD 34,000 TD 10,000 D <500 D <6 <17 <9 80 <7 50 180 TD <4 60
<5.60 <56,000 D <5.20 <49,000 D <75,000 D <9,700 D <500 D <6 <17 <9.80 <7.50 <460 D <4 60
<5.60 <56,000 D <5.20 <49,000 D <75,000 D <9,700 D <500 D <6 <17 <9.80 <7.50 <460 D <4.60
<5.60 <56,000 D <5.20 16,000 TD <75,000 D 3,700 TD <500 D <6 <17 <9.80 <7.50 <460 D <4.60
<5 60 <56,000 D <5.20 <49,000 D <75,000 D <9,700 D <500 D <6 <17 <9.80 <7.50 <460 D <4 60
<11 280,000 D 14 1,700,000 D 2,400,000 D 470,000 D 3,000 DJ 54 <34 <20 <15 2,500 DJ 3.4 T
<5.60 98,000 D 5.2 700,000 D 960,000 D 230,000 D 1300 D 32 <17 <9.80 <7.50 150 TD 2.1 T
nc 378,000 19.2 2,400,000 3,360.000 700,000 4,200 86 nc nc nc 2,650 5.5
17 <56,000 D 2.5 T <49,000 D <75,000 D <9,700 D <500 D <6
<17 <9.80 <7.50 <460 D <4.60
<560 <56,000 D 7 680,000 D 93,000 D 43,000 D <500 D <6 <17 <9 80 <7.50 <460 D <4 60
2 T <56,000 D 1.7 T <49,000 D <75,000 D <9,700 D <500 D 16 <17 <9.80 <7.50 <460 D 3.9 T
<5.60 <56,000 D <5.20 <49,000 D <75,000 D <9,700 D <500 DUJ <6 <17 <9.80 <7.50 <460 DUJ <4.60
26 T 1,000 77 250,000 590 <52 1,900 19 T 310 <39 <45 <34 <38
9.7 J <8.20 <7.80 <8.40 <10 <11 13 J <7.70 53 J <7.90 <9.20 4.6 TJ 21
<44 28 T <38 <41 <50 <52 UJ <34 <38 <45 18 T <45 <34 <38
<44 <40 <38 <41 <50 <52 <34 42 <45 21 T 26 T <34 <38
<9 <8.20 <7.80 <8.40 <10 <11 <7 <7.70 <9.10 <7.90 <9.20 <6.90 <7.70
<44 <40 <38 <41 <50 <52 <34 <38 <45 89 <45 <34 16 T
<9 47 <7.80 <8.40 <10 <11 170 <7.70 <9.10 <7.90 <9.20 <6.90 <7.70
130 J 200 J 40 J 8,500 J <5 38 J <3.40 94 J 50 J <3.90 <4.50 4.2 J 4.5
<9 <8.20 <7.80 <8.40 <10 760 <7 <7.70 <9.10 <7.90 <9.20 <6.90 <7.70
(,) May 2015 EPA Regions 3,6, and 9 Limiting Industrial Soil Regional Screening Levels (carcinogenic target risk of 1 O'6 or noncancer with hazard index of 1, whichever is lower) Reference: www.epa.gov/region9/superfund/prg
<b> The focused shallow soil investigation was designed to assess the extent of shallow soil contamination discovered at MW-33D during drilling operations in October 2011, shallow soil analytical results for MW-33D are included here for reference
(c) Total xylene was calculated by summing laboratory results for m,p-xylene and o-xylene, data recorded below reporting limits (i.e., <9,700) were excluded from the summation.
(d) Borings were typically advanced to a depth of 5 feet, though recovered core samples often did not include the lower soil section due to soft or loose soils slipping out of the sampling sleeve
Analyte not detected, however, the reporting limit is greater than the industrial soil screening level (due to necessary sample dilution).
Constituent detected above the industrial soil screening level.
Hg/kg
mg/1
Bold
D
E
J
M
micrograms per kilogram MCL
milligrams per liter na
Bolded result indicates positively identified compound. nc
Not scheduled NE
Sample dilution required for analysis, reported values reflect the dilution. R
Data are estimated Result exceeded calibration range; no dilution was analyzed. T
Data are estimated due to associated quality control data. UB
Possible matrix effect UJ
Maximum contaminant level
not analyzed
not calculated
not established
Associated quality control did not meet acceptance criteria.
Analyte was positively identified but the reported concentration is estimated; reported concentration is less than the reporting limit, but greater than the method detection limit
Analyte considered not detected based on associated blank data.
Potential low bias, possible false negative.
NA - not applicable
ppm - parts per million
Table B-3. 2013 Focused Shallow Soil Investigation Results
Source: Table A-1. Focused Shallow Soil Investigation Analytical Results - May 2013 Wasatch Chemical Site, Salt Lake City, Utah From MWH-Stantec. 2017. Human Health Risk Assessment for Shallow Soils in the Focused Investigation Area at the Wasatch Chemical Site, Salt
Lake City, Utah. August 28.
TABLE A-l
FOCUSED SHALLOW SOIL INVESTIGATION ANALYTICAL RESULTS - MAY 2013
WASATCH CHEMICAL SITE, SALT LAKE CITY, UTAH
(Page 2 of 4)
Location Identification DPSS-14 DPSS-15 DPSS-15 DPSS-16 DPSS-16 DPSS-17 DPSS-17 DPSS-18 DPSS-18 DPSS-19 DPSS-19 DPSS-20 DPSS-20 DPSS-21 DPSS-21 DPSS-22 DPSS-22
DPSS-23 DPSS-23 DPSS-24 DPSS-24 DPSS-25 DPSS-26 DPSS-26
Field Sample Identification DPSS-14-2.9 DPSS-15-2.0 DPSS-15-3.0 DPSS-16-2.0 DPSS-16-5.0 DPSS-17-2.4 DPSS-17-4.4 DPSS-18-1.6 DPSS-18-3.3 DPSS-19-0.8 DPSS-19-3.0 DPSS-20-2.2 DPSS-20-4.5 DPSS-21-0.8 DPSS-21-4.0 DPSS-22-1.7 DPSS-22-3.8 DPSS-23-2.4 DPSS-23-3.3 DPSS-24-1.7 DPSS-24-2.8 DPSS-25-3.0 DPSS-26.2.1 DPSS-26-3.8
Date Collected 5/6/2013 5/6/2013 5/6/2013 5/6/2013 5/6/2013 5/8/2013 5/8/2013 5/8/2013 5/8/2013 5/8/2013 5/8/2013 5/8/2013 5/8/2013 5/8/2013 5/8/2013 5/8/2013 5/8/2013 5/8/2013 5/8/2013 5/8/2013 5/8/2013 5/8/2013 5/8/2013 5/8/2013
Sample Depth (ft)2.9 2.0 3.0 2.0 5.0 2.4 4.4 1.6 3.3 0.8 3.0 2.2 4.5 0.8 4.0 1.7 3.8 2.4 3.3 1.7 2.8 3.0 2.1 3.8
Depth to Saturated Zone (ft)2.8 2.0 2.0 4.4 4.4 3.8 3.8 2.7 2.7 3.8 3.8 3.7 3.7 3.8 3.8 3.7 3.7 3.9 3.9 >2.9 >2.9 2.5 2.2 2.2
Maximum Depth of Recovered Soil(a) (b) (c) (d) (ft)3.5 3.5 3.5 8.0 8.0 4.5 4.5 3.5 3.5 3.5 3.5 5.0 5.0 4.0 4.0 4.0 4.0 4.0 4.0 3.0 3.0 3.0 4.5 4.5
Industrial Soil
Screening Le\'els(a)
Photo-ionization Detector Reading (ppm)
( Vg/kg)
NA 1,609 3 569 0 3 0 0 0 0 0 0 0 0 0 0 0 364 1 14 6 147 0 17 380
Volatile Organic Compounds (pg/kg)
1,1,1 -Tr ichloroethane 36,000,000 <67,000 D <5.40 <350,000 D <5.90 <970 D <5.80 <5.10 <8.30 <9.20 <5.60 <8.40 <6.60 <10 <6.80
2.6 T <5.90 <13,000 D <6.30 <230 D <5.60 <1,800 D 3.3 T 86 <180,000 D
1,1 -Dichloroethane 16,000 <67,000 D <5.40 <350,000 D <5.90 <970 D <5.80 <5.10
<8.30 <9.20 <5.60 <8.40 <6.60 <10 <6.80 2.6 T <5.90 <13,000 D <6.30 <230 D <5.60 <1,800 D <5.50 14 <180,000 D
1,1 -Dichloroethene 1,000,000 <67,000 D <5.40 <350,000 D <5.90 <970 D <5.80 <5.10 <8.30 <9.20 <5.60 <8.40 <6.60 <10 <6.80 <8.30
<5.90 <13,000 D <630 <230 D <5.60 <1,800 D <5.50 <6.30 <180,000 D
1,2,4-Trimethylbenzene 240,000 <67,000 D <5.40 <350,000 D <5.90 <970 D <5.80 <5.10 <8.30 <9.20 <5.60 <8.40 <6.60 <10 <6.80 <8.30 <5.90 <13,000 D <6 30 <230 D <5.60 <1,800 D <5.50 <6.30 <180,000 D
1,2-Dichloroethane 2,000 <67,000 D <5.40 <350,000 D <5.90 <970 D <5.80 <5.10 <8.30 <9.20 <5.60 <8.40 <6.60 <10 <6.80 <8.30 <5.90 <13,000 D <6,30 <230 D <5.60 <1,800 D <5.50 <6.30 <180,000 D
1,3,5-Trimethylbenzene (Mesitylene)12,000,000 <67,000 D <5.40 <350,000 D <5.90 <970 D <5.80 <5.10 <8.30 <9.20 <5.60 <8.40 <6.60 <10 <6,80 <8.30 <5.90 <13,000 D <6 30 <230 D <5.60 <1,800 D <5.50 <6.30 <180,000 D
2-Chlorotoluene 23,000,000 <67,000 D <5.40 <350,000 D <5.90 <970 D <5.80 <5.10 <8.30 <9.20 <5.60 <8.40 <6.60 <10 <6.80 <8.30 <5.90 <13,000 D <6.30 <230 D <5.60 <1,800 D <5.50 <6.30 <180,000 D
Acetone 670,000,000 <67,000 D <5.40 UJ <350,000 DUJ 55 UBJ <970 D 1.8 T 5.7 <8.30 81 <5.60 56 67 95 <6.80 4.2 T 7.1 <13,000 DUJ 2.2 TJ <230 DUJ 10 <1,800 DUJ 2.6 T 4.7 T <180,000 DUJ
Benzene 5,100 <67,000 D <5.40 <350,000 D <5.90 <970 D <5.80 <5.10 <8.30 <9.20 <5.60 <8.40 <6.60 <10 <6.80 <8.30 <5.90 <13,000 D <6.30 <230 D <5.60 <1,800 D <5.50 <6.30 <180,000 D
Carbon disulfide 3,500,000 <67,000 D <5.40 <350,000 D <5.90 <970 D <5.80 <5.10 <8.30 <9.20 <5.60 <8.40 <6.60 <10 <6.80 <8.30 <5.90 <13,000 D <6 30 <230 D <5.60 <1,800 D <5.50 2.5 T <180,000 D
Chloroethane NE <67,000 D <5.40 <350,000 D <5.90 <970 D <5.80 <5.10 <8.30 <9.20 <5.60 <8.40 <6.60 <10 <6.80 <8.30 <5.90 <13,000 D <6.30 <230 D <5.60 <1,800 D <5.50 <6.30 <180,000 D
Chloroform 1,400 <67,000 D <5.40 <350,000 D <5.90 <970 D <5.80 <5.10 <8.30 <9.20 <5.60 <8.40 <6.60 <10 <6.80 24 <5.90 <13,000 D <6.30 <230 D <5.60 <1,800 D <5.50 3.5 T <180,000 D
cis-l,2-Dichloroethene 2,300,000 <67,000 D 1.6 T <350,000 D <5.90 <970 D <5.80 1.5 T <8.30 <9.20 <5.60 <8.40 <6.60 4.3 T <6.80 <8.30 <5.90 <13,000 D 92 620 D 6.9 2,600 D 6.8 120 <180,000 D
Ethylbenzene 25,000 280,000 D <5.40 1,200,000 D 7.6 5,700 D <5.80 <5.10 <8.30 <9.20 <5.60 <8.40 <6.60 <10 <6.80 <8.30 <5.90 33,000 D <6.30 250 D <5.60 6,500 D 7 4.6 T 260,000 D
Isopropylbenzene (Cumene)9,900,000 <67,000 D <5.40 <350,000 D <5.90 310 TD <5.80 <5.10 <8.30 <9.20 <5.60 <8.40 <6.60 <10 <6.80 <8.30 <5.90 <13,000 D <6.30 <230 D <5.60 <1,800 D <5.50 <6.30 <180,000 D
Methyl ethyl ketone (2-Butanone)190,000,000 <67,000 D <5.40 <350,000 D 2.3 T <970 D <5.80 <5.10 <8.30 16 <5.60 9.1 14 17 <6.80 <8.30 <5.90 <13,000 D <6.30 <230 D <5.60 <1,800 D <5.50 <6.30 <180,000 D
Methylene chloride 1,000,000 <67,000 D <5.40 <350,000 D <5.90 <970 D <5.80 <5.10 <8.30 <9.20 <5.60 <8.40 <6.60 <10 <6.80 <8.30 <5.90 <13,000 D <6.30 <230 D <5.60 <1,800 D <5.50 <6.30 <180,000 D
n-Propylbenzene NE <67,000 D <5.40 <350,000 D <5.90 <970 D <5.80 <5.10 <8.30 <9.20 <5.60 <8.40 <6.60 <10 <6.80 <8.30 <5.90 <13,000 D <6.30 <230 D <5.60 <1,800 D <5.50 <6.30 <180,000 D
Naphthalene 17,000 <67,000 D <5.40 <350,000 D <5.90 <970 D <5.80
<5.10 <8.30 <9.20 <5.60 <8.40 4.2 T <10 <6.80 <8.30 UJ <5.90 UJ <13,000 D <6.30 UJ <230 D <5.60 UJ <1,800 D <5.50 UJ <6.30 UJ <180,000 D
m,p-Xylene (Sum of isomers)NE 1,400,000 D <11 6,000,000 D 50 20,000 D <12 <10 <17 <18 <11 <17 <13 <20 <14 <17 <12 280,000 D 2.7 T 670 D 5.9 T 34,000 D 49 73 3,700,000 D
o-Xylene (1,2-Dimethylbenzene)2,800,000 500,000 D <5.40 2,300,000 D 59 8,900 D <5.80 <5.10 <8.30 <9.20 <5.60 <8.40 <6.60 <10 <6.80 <8.30 <5.90 92,000 D <6.30 380 D 2.5 T 14,000 D 33 27 1,400,000 D
Total Xylene (Sum of all 3 isomers)c)2,500,000 1,900,000 nc 8,300,000 109 28,900 nc nc nc nc nc nc nc nc nc nc nc 372,000 2,7 1,050 8.4 48,000 82 100 3,700,000
Tetrachloroethene (PCE)100,000 <67,000 D <5.40
<350,000 D 21 <970 D 11 <5.10 <8.30 <9.20 <5.60 <8.40 <6.60 <10 <6.80 <8.30 <5.90 <13,000 D 340 100 TD 29 5,700 D 20 150 690,000 D
Toluene 47,000,000 150,000 D <5.40 1,600,000 D 12 4,800 D <5.80 <5.10 <8.30 <9.20 <5.60
<8.40 <6.60 <10 <6.80 <8.30 <5.90 79,000 D <630 <230 D <5.60 7,500 D 8.8 2.7 T 200,000 D
Trichloroethene (TCE)6,000 25,000 TD <5.40 <350,000 D 15 <970 D <5.80 <5.10 <8.30 <9.20 <5.60 <8.40 <6.60 <10 <6.80 <8.30 <5.90 <13,000 D 50 <230 D 10 4,500 D 8.8 150 <180,000 D
Vinyl chloride 1,700 <67,000 D <5.40 <350,000 D <5.90 <970 D <5.80 <5.10 <8.30 <9.20 <5.60 <8.40 <6.60 <10 <6.80 <8.30 <5.90 <13,000 D <6.30 <230 D <5.60 <1,800 D <5.50 7.5 <180,000 D
Herbicides (pg/kg)
2,4 DB 6,600,000 2,200 <36 430 <40 <58 <37 <41 <390 D <53 <39 <53 <41 <46 <38 <470 D <38 <630 D <370 D 18 T <36 77 J 21 T <42 2,300 DJ
2,4,5-T (Trichlorophenoxyacetic acid)8,200,000 <9.40 <7.40
<9 <8.10 <12 45 J 8.2 TJ <79 D 34 J <7.90 <11 23 J 190 J <7.80 <95 D <7.80 97 TDJ <76 D <7.70 <7.40 75 J 4.1 TJ <8.40 <88 D
2,4-D (Dichlorophenoxyacetic acid)9,700,000 <46 <36 <44 <40 <58 <37 <41 <390 D <53 <39 <53 <41 <46 <38 <470 DUJ <38 <630 DUJ <370 D <38 <36 <48 UJ <41 <42 <430 DUJ
Dalapon 25,000,000 37 T 17 T <44 <40 39 T 24 T 18 T <390 D 31 T <39 28 T <41 <46 <38 <470 D 35 T <630 D <370 D 24 T 24 T 43 TJ 29 T <42 <430 D
Dicamba 25,000,000 <9.40 <7.40 <9 <8.10 <12 <7.40 <8.30 <79 D <11 <7.90 <11 <8.40 <9.30 <7.80 <95 D <7.80 <130 D <76 D <7.70 <7.40 <9.80 <8.30 <8.40 <88 D
Dichloroprop NE 85 12 T 62 <40 <58 15 T <41 <390 D <53 <39 <53 <41 <46 <38 <470 D <38 <630 D <370 D <38 <36 <48 <41 <42 <430 D
Dinoseb 820,000 95 <7.40 <9 <8.10 <12 <7.40 <8.30 <79 D 27 <7.90 10 T <8.40 30 <7.80 <95 D <7.80 <130 D <76 D <7.70 <7.40 <9.80 87 J <8.40 <88 D
Pentachlorophenol 4,000 <4.60 3.5 T <4.40 <4 <5.80 3.6 T <4.10 <39 D 59 73 66 8 5.6 <3.80 220 DJ 3.7 TJ 6,200 DJ <37 D 17 J 17 J 230 J 250 J 7.1 J 3,000 DJ
Silvex (2,4,5-TP)6,600,000 <9.40 <7.40
<9 <8.10 36 <7.40 <8.30 <79 D <11 <7.90 <11 <8.40 <9.30 <7.80 <95 D <7.80 <130 D <76 D <7.70 <7.40 60 J <8.30 <8.40 <88 D
(a) May 2015 EPA Regions 3, 6, and 9 Limiting Industrial Soil Regional Screening Levels (carcinogenic target risk of Kf6 or noncancer witih hazard index of 1, whichever is lower). Reference: www.epa.gov/region9/superfund/prg
(b) The focused shallow soil investigation was designed to assess the extent of shallow soil contamination discovered at MW-33D during drilling operations in October 2011; shallow soil analytical results for MW-33D are included here for re
(c) (e) Total xylene was calculated by summing laboratory results for m,p-xylene and o-xylene; data recorded below reporting limits (i.e., <9,700) were excluded from the summation.
(d)
Analyte not detected; however, the reporting limit is greater than the industrial soil screening level (due to nece
Concentration detected above the industrial soil screening level
Ug/kg gg/kg micrograms per kilogram MCL Maximum contaminant level
mg/1 mg/1 milligrams per liter na not analyzed
Bold Bold Bolded result indicates positively identified compound.nc not calculated
--Not scheduled NE not established
D D Sample dilution required for analysis; reported values reflect the dilution.R Associated quality control did not meet acceptance criteria.
E E Data are estimated. Result exceeded calibration range, no dilution was analyzed.T Analyte was positively identified but the reported concentration is estimated, reported concentration is less than the reporting limit, but greater than the method detection limit.
J J Data are estimated due to associated quality control data.UB Analyte considered not detected based on associated blank data.
M M Possible matrix effect UJ Potential low bias, possible false negative.
NA - not applicable
ppm - parts per million
Table B-3. 2013 Focused Shallow Soil Investigation Results
Source: Table A-1. Focused Shallow Soil Investigation Analytical Results - May 2013 Wasatch Chemical Site, Salt Lake City, Utah From MWH-Stantec. 2017. Human Health Risk Assessment for Shallow Soils in the Focused Investigation Area at the Wasatch Chemical Site, Salt
Lake City, Utah. August 28.
TABLE A-l
FOCUSED SHALLOW SOIL INVESTIGATION ANALYTICAL RESULTS - MAY 2013
WASATCH CHEMICAL SITE, SALT LAKE CITY, UTAH
(Page 3 of 4)
Location Identification DPSS-27 DPSS-27 DPSS-28 DPSS-28 DPSS-29 DPSS-30 DPSS-30 DPSS-31 DPSS-31
DPSS-32 DPSS-32 DPSS-33 DPSS-33 DPSS-34 DPSS-34 DPSS-35 DPSS-35 DPSS-36 DPSS-37 DPSS-38 DPSS-38 DPSS-39 DPSS-40 DPSS-40
Field Sample Identification DPSS-27-4.1 DPSS-27-6.5 DPSS-28-5.5 DPSS-28-9.8 DPSS-29-3.2 DPSS-30-2.0 DPSS-30-4.0 DPSS-31-2.8 DPSS-31-3.7 DPSS-32-1.4 DPSS-32-2.0 DPSS-33-2.2 DPSS-33-3.5 DPSS-34-1.6 DPSS-34-2.2 DPSS-35-1.6 DPSS-35-3.3
DPSS-36-3.4 DPSS-37-1.8 DPSS-38-2.2 DPSS-38-4.0 DPSS-39-1.2 DPSS-40-1.7 DPSS-40-2.6
Date Collected 5/8/2013 5/8/2013 5/8/2013 5/8/2013 5/10/2013 5/10/2013 5/10/2013 5/10/2013 5/10/2013 5/10/2013 5/10/2013 5/10/2013 5/10/2013 5/10/2013 5/10/2013 5/10/2013 5/10/2013 5/10/2013 5/10/2013 5/10/2013 5/10/2013 5/10/2013 5/20/2013 5/20/2013
Sample Depth (ft)4.1 6.5 5.5 9.8 3.2 2.0 4.0 2.8 3.7 1.4 2.0 2.2 3.5 1.6 2.2 1.6 3.3 3.4 1.8 2.2 4.0 1.2 1.7 2.6
Depth to Saturated Zone (ft)2.2 2.2 2.2 2.2 2.3 2.0 2.0 2.4 2.4 2.0 2.0 2.4 2.4 3.0 3.0 2.2 2.2 2.7 2.1 2.2 2.2 2.5 2.0 2.0
Maximum Depth of Recovered Soil<d) (ft)10.0 10.0 10.0 10.0 3.5 4.5 4.5 4 4 2.0 2.0 3.5 3.5 4.0 4.0 3.8 3.8 3.5 3.5 4.3 4.3 3.0 3.5 3.5
Industrial Soil
Screening Lei'els(a>
(Mgrtg)
Photo-ionization Detector Reading (ppm)
Volatile Organic Compounds (pg/kg)
1,1,1 -Trichloroethane
1.1- Dichloroethane
1.1- Dichloroethene
1.2.4- Trimethylbenzene
1.2- Dichloroethane
1.3.5- Trimethylbenzene (Mesitylene)
2-Chlorotoluene
Acetone
Benzene
Carbon disulfide
Chloroethane
Chloroform
cis-1,2-Dichloroethene
Ethylbenzene
Isopropylbenzene (Cumene)
Methyl ethyl ketone (2-Butanone)
Methylene chloride
n-Propylbenzene
Naphthalene
m,p-Xylene (Sum of isomers)
o-Xylene (1,2-Dimethylbenzene)
Total Xylene (Sum of all 3 isomers )* (b) (c)
Tetrachloroethene (PCE)
Toluene
Trichloroethene (TCE)
Vinyl chloride
Herbicides (pg/kg)
2,4 DB
2.4.5- T (Trichlorophenoxyacetic acid)
2,4-D (Dichlorophenoxyacetic acid)
Dalapon
Dicamba
Dichloroprop
Dinoseb
Pentachlorophenol
Silvex (2,4,5-TP)
NA 88 1,058 935 63 21 3 793 0 1 16 2,062
36,000.000 21 <5,600 D 49,000 TD <930 D <11,000 D 3.6 T <130,000 D <6.60 <6.30 <1,200 D <300,000 D
16,000 4.9 T <5,600 D <140,000 D <930 D <11,000 D 2.6 T <130,000 D <6.60 <6.30 <1,200 D <300,000 D
1,000,000 <5.80 <5,600 D <140,000 D <930 D <11,000 D <6.70 <130,000 D <6.60 <6.30 <1,200 D <300,000 D
240,000 <5.80 <5,600 D <140,000 D <930 D <11,000 D <6.70 <130,000 D <6.60 <6.30 <1,200 D <300,000 D
2,000 <5.80 <5,600 D <140,000 D <930 D <11,000 D <6.70 <130,000 D <6.60 <6.30 <1,200 D <300,000 D
12,000,000 <5.80 <5,600 D <140,000 D <930 D <11,000 D <670 <130,000 D <6 60 <6.30 <1,200 D <300,000 D
23,000,000 <5.80 <5,600 D <140,000 D <930 D <11,000 D <670 <130,000 D <6.60 <6.30 <1,200 D <300,000 D
670.000,000 2.9 T <5,600 DUJ <140,000 DUJ <930 DUJ <11,000 DUJ 2.5 T <130,000 DUJ 5.9 T 6.7 <1,200 DUJ <300,000 DUJ
5,100 <5.80 <5,600 D <140,000 D <930 D <11,000 D <6.70 <130,000 D <6.60 <6.30 <1,200 D <300,000 D
3,500,000 <5.80 <5,600 D <140,000 D <930 D <11,000 D <6 70 <130,000 D <6 60 <6.30 <1,200 D <300,000 D
NE <5.80 <5,600 D <140,000 D <930 D <11,000 D <6.70 <130,000 D <6.60 <6.30 <1,200 D <300,000 D
1,400 <5.80 <5,600 D <140,000 D <930 D <11,000 D <6.70 <130,000 D <6.60 <630 <1,200 D <300,000 D
2,300,000 73 <5,600 D <140,000 D <930 D <11,000 D 16 <130,000 D <6 60 <630 <1,200 D <300,000 D
25,000 <5.80 15,000 D 450,000 D 3,000 D 19,000 D <6.70 75,000 TD <6 60 21 3,300 D 4,200,000 D
9,900,000 <5.80 <5,600 D <140,000 D <930 D 3,400 TD <6 70 <130,000 D <6 60 2.9 T <1,200 D 230,000 TD
190,000,000 <5.80 <5,600 D <140,000 D <930 D <11,000 D <6.70 <130,000 D <6.60 <6.30 <1,200 D <300,000 D
1,000,000 <5.80 <5,600 D <140,000 D <930 D <11,000 D <6.70 <130,000 D <6.60 <6.30 <1,200 D 120,000 TD
NE <5.80 <5,600 D <140,000 D <930 D <11,000 D <6.70 <130,000 D <6 60 1.9 T <1,200 D 120,000 TD
17,000 <5 80 UJ <5,600 D <140,000 D <930 D <11,000 D <6 70 <130,000 D <6 60 <6.30 <1,200 D <300,000 D
NE 3 T 82,000 D 2,500,000 D 14,000 D 110,000 D 2.1 T 1,000,000 D <13 130 15,000 D 18,000,000 D
2,800,000 4.3 T 31,000 D 920,000 D 5,800 D 51,000 D <6.70 410,000 D <6.60 55 6,700 D 7,500,000 D
2,500,000 7.3 113,000.0 3,420,000 19,800 161,000 9 1,410,000 nc 185 21,700 25,500,000
100,000 98 2,800 TD 67,000 TD 300 TD <11,000 D 9.3
60,000 TD 3.5 T 3.4 T <1,200 D <300,000 D
47,000,000 <5.80 10,000 I)380,000 D 7,200 D <11,000 D <6 70 <130,000 D <6 60 <6.30 <1,200 D 540,000 D
6,000 61 <5,600 D <140,000 D <930 D <11,000 D 3.5 T <130,000 D 3.1 T <6 30 <1,200 D <300,000 D
1,700 <5.80 <5,600 D <140,000 D <930 D <11,000 D <6.70 <130,000 D <6.60 <6.30 <1,200 D <300,000 D
6,600,000 <420 D 220 <40 210 J <400 D 22 T 390 240 160 300 <630 D
8,200,000 <85 D <830 93 J <7.50 <81 D 16 J <8 80 <9.30 <8.30 <7.40 <130 D
9,700.000 <420 D 46 98 J 42 J <400 DUJ <40 <43 <46 <41 20 T <630 D
25,000,000 <420 D 55 <40 48 J <400 D <40 <43 <46 <41 <37 <630 D
25,000,000 <85 D 55 J <8.20 18 J <81 D <8 <8.80 <9.30 <8.30 39 J <130 D
NE <420 D <41 <40 <37 <400 D <40 <43 <46 <41 <37 <630 D
820,000 350 DJ <8.30 <8 20 240 J <81 D <8 <8 80 <9.30 <8.30 88 J <130 D
4,000 360 DJ 800 J 19,000 J 820 J 73 DJ 2.4 TJ 60 J 1.1 TJ 3 TJ <3.70 31 TDJ
6,600,000 <85 D <8.30 <8 20 <7.50 <81 D <8 <8.80 <9.30 <830 25 1,600 D
0 0 0 0 2 49 2 0 0 125 0 1 10
340 5.7 T <5.60 27 <6 <140,000 D <58,000 D <5.90 <6 <200,000 D <6.30 <4.60 <1,400 D
190 180 <5.60 21 2.1 T <140,000 D <58,000 D <5.90 <6 <200,000 D <6 30 2 T <1,400 DUJ
7.4 T <18 <5.60 <6.90 <6 <140,000 D <58,000 D <5.90 <6 <200,000 D <6.30 <4.60 <1,400 DUJ
<8 50 <18 <5.60 <6.90 <6 <140,000 D <58,000 D <5.90 <6 <200,000 D <6.30 <4.60 <1,400 D
<8 50 <18 <5.60 <6.90 <6 <140,000 D <58,000 D <5.90 <6 <200,000 D <6.30
<4 60 UJ <1,400 D
<8.50 <18 <5.60 <6.90
<6 <140,000 D <58,000 D <5.90 <6 <200,000 D <630 1.4 T 530 TD
<8.50 <18 <5.60 <6.90 <6 <140,000 D 18,000 TD <5.90 <6 <200,000 D <6.30 1.4 T <1,400 D
<8 50 19 29 14 34 <140,000 DUJ <58,000 DUJ <5.90 3 T <200,000 DUJ 2 T 16 J <1,400 D
<8.50 <18 <5.60 <6 90 <6 <140,000 D <58,000 D <5.90 <6 <200,000 D <6.30 <4 60 <1,400 DUJ
<8.50 <18 <5.60 <6 90 <6 <140,000 D <58,000 D <5.90 <6 <200,000 D <6.30 <4.60 <1,400 DUJ
<8 50 13 T <5.60 <6.90 <6 <140,000 D <58,000 D <5 90 <6 <200,000 D <6.30 <4.60 <1,400 DUJ
9.9 <18 <5.60 <6.90 <6 <140,000 D <58,000 D <5.90 <6 <200,000 D <6 30 <4 60 <1,400 D
120 <18 <5.60 21 22 <140,000 D <58,000 D 5.6 T 3.4 T <200,000 D <6.30 3.6 T <1,400 D
<8 50 <18 <5.60 <6.90 <6 540,000 D 48,000 TD <5.90 <6 470,000 D <6.30 35 7,000 DJ
<8.50 <18 <5.60 <6.90 <6 <140,000 D <58,000 D <5.90 <6 <200,000 D <6 30 1.7 T 730 TD
<8 50 <18 <5.60 <6.90 8 <140,000 D <58,000 D <5.90 <6 <200,000 D <6.30 2.8 T <1,400 D
<8 50 <18 1.7 T <6.90 <6 <140,000 D <58,000 D <5.90 <6 <200,000 D <6.30 <4 60 <1,400 D
<8.50 <18 <5.60 <6 90 <6 <140,000 D <58,000 D <5.90 <6 <200,000 D <6.30 <4.60 640 TD
<8.50 <18 <5.60 <6.90 <6 <140,000 D <58,000 D <5.90 <6 <200,000 D <6.30 <4.60 UJ <1,400 D
<17 <36 <11 23 T 4.7 T 5,200,000 D 610,000 D 5.9 T 5.8 T 2,400,000 D 2.9 T 6.8 T 39,000 D
<8 50 <18 <5.60 <6.90 3.9 T 1,800,000 D 230,000 D 2.8 T 2.9 T 830,000 D <6.30 4.6 12,000 D
nc nc nc 2.3 8.6 7,000,000 840,000 8.7 8 7 3,230,000 2.9 114 51,0000
190 <18 2.9 T 130 11 88,000 TD <58,000 D 70 24 810,000 D 6.5 <4 60 <1,400 D
<8.50 <18 <5.60 <6.90 2.4 T 950,000 D 190,000 D 2.2 T 2.3 T 620,000 D <6.30 2.2 T <1,400 D
98 <18 3.6 T 120 59 <140,000 D <58,000 D 24 27 <200,000 D 3.4 T <4 60 <1,400 D
<8 50 <18 <5.60 5.8 T <6 <140,000 D <58,000 D <5.90 <6 <200,000 D <6.30 1.4 TJ <1,400 DUJ
210 TD <53 180 46 380 <440 D <420 D 93 <40 <490 D 420 110 <400 DUJ
<100 D <11 <7.50 <9.20 8.2 TJ <88 D 510 DJ 8.4 J <8.10 <99 D 4.7 TJ <7.60 48 TDJ
<520 D <53 <37 <46 <43 <440 D <420 D 59 <40 <490 D <36 <38 1,500 DJ
<520 D <53 <37 <46 <43 <440 D <420 D <40 <40 <490 D <36 <38 <400 D
<100 D <11 <7.50 18 J <8 80 <88 D <86 D <8.10 <8.10 <99 D <7.40 <7 60 <82 D
<520 D <53 <37 <46 <43 <440 D <420 D 380 <40 <490 D <36 <38 <400 D
440 DJ 55 J 11 J 26 J 19 J <88 D 6,700 DJ 26 J <8 10 290 DJ <7.40 <7.60 <82 D
380 DJ 6 J <3.70 25 J 4.3 J 1,000 DJ 28,000 DJ 27 J 19 J 1,300 DJ 29 J 30 T 2,200 DJ
<100 D <11 <7.50 <9.20 <8.80 <88 D <86 D <8.10 <8 10 <99 D <7.40 <7 60 <82 D
Mg/kg
mg/1
Bold
D
E
J
M
(,) May 2015 EPA Regions 3,6, and 9 Limiting Industrial Soil Regional Screening Levels (carcinogenic target risk of 10-6 or noncancer with hazard index of 1, whichever is lower) Reference www epa gov/region9/superfund/prg
(b) The focused shallow soil investigation was designed to assess the extent of shallow soil contamination discovered at MW-33D during drilling operations in October 2011, shallow soil analytical results for MW-33D are included here for re
(c) Total xylene was calculated by summing laboratory results for m,p-xylene and o-xylene, data recorded below reporting limits (i e , <9,700) were excluded from the summation
Analyte not detected; however, the reporting limit is greater than the industrial soil screening level (due to necc
Concentration detected above the industrial soil screening level
pg/kg micrograms per kilogram
mg/1 milligrams per liter
Bold Bolded result indicates positively identified compound
- Not scheduled
D Sample dilution required for analysis, reported values reflect the dilution.
E Data are estimated Result exceeded calibration range, no dilution was analyzed.
J Data are estimated due to associated quality control data.
M Possible matrix effect
MCL Maximum contaminant level NA - not applicable
na not analyzed ppm - parts per million
nc not calculated
NE not established
R Associated quality control did not meet acceptance criteria.
T Analyte was positively identified but the reported concentration is estimated; reported concentration is less than the reporting limit, but greater than the method detection limit
UB Analyte considered not detected based on associated blank data.
UJ Potential low bias, possible false negative
Table B-3. 2013 Focused Shallow Soil Investigation Results
Source: Table A-1. Focused Shallow Soil Investigation Analytical Results - May 2013 Wasatch Chemical Site, Salt Lake City, Utah From MWH-Stantec. 2017. Human Health Risk Assessment for Shallow Soils in the Focused Investigation Area at the Wasatch Chemical Site, Salt
Lake City, Utah. August 28.
Location Identification DPSS-41 DPSS-41 DPSS-42 DPSS-43 DPSS-43 DPSS-44 DPSS-45 DPSS-45 DPSS-46 DPSS-46 DPSS-47 DPSS-47 DPSS-48 DPSS-49 DPSS-49
DPSS-50 DPSS-51 DPSS-52 DPSS-53 DPSS-53
Field Sample Identification DPSS-41-1.6 DPSS-41-2.0 DPSS-42-1.9 DPSS-43-0.8 DPSS-43-2.7 DPSS-44-1.2 DPSS-45-1.6 DPSS-45-3.0 DPSS-46-1.3 DPSS-46-2.2 DPSS-47-2.4 DPSS-47-4.0 DPSS-48-3.6 DPSS-49-1.5 DPSS-49-3.2 DPSS-50-3.4 DPSS-51-2.1 DPSS-52-2.3 DPSS-53-2.3 DPSS-53-3.1
Date Collected 5/20/2013 5/20/2013 5/20/2013 5/20/2013 5/20/2013 5/20/2013 5/20/2013 5/20/2013 5/20/2013 5/20/2013 5/20/2013 5/20/2013 5/22/2013 5/22/2013 5/22/2013 5/22/2013 5/22/2013 5/22/2013 5/22/2013 5/22/2013
Sample Depth (ft)1.6 2.0 1.9 0.8 2.7 1.2 1.6 3.0 1.3 2.2 2.4 4.0 3.6 1.5 3.2 3.4 2.1 2.3 2.3 3.1
Depth to Saturated Zone (ft)1.7 1.7 2.2 23 2.3 2.5 1.8 1.8 2.5 2.5 2.3 2.3 3.5 3.0 3.0 3.7 2.0 2.2 2.2 2.2
Maximum Depth of Recovered Soil<d)(ft)2.0 2.0 3.2 3.0 3.0
2.7 3.5 3.5 2.5 2.5 4.5 4.5 5.0 3.2 3.2 4.0 2.8 3.5 3.8 3.8
Industrial Soil
Screening Levels,a>
(Mg/kg)
Photo-ionization Detector Reading (ppm)NA 0 0 0 0 0 0 1 150 4 257 10 1,394 0 0 26 0 0 0 0 0
Volatile Organic Compounds (pg/kg)
1,1,1 -T richloroethane 36,000.000 <5.50 <9.50 <4.60 <4.40 9.9 <240 D 5.1 T <3,800 D <12 <6,600 D 5.3 T <57,000 D <4.40 <5.60 <720 D <6.40 <14 <7.10 <8.20 <10
1,1-Dichloroethane 16,000 <5.50 23 <4.60 <4.40 31 <240 D 2.7 T <3,800 D <12 <6,600 D 9.1 T <57,000 D <4.40 <5.60 <720 D <6.40 7.8 T <7.10 <8 20 <10
1,1-Dichloroethene 1,000,000 <5.50 <9.50 <4.60 <4.40 <7.20 <240 D <5 80 <3,800 D <12 <6,600 D <9.70 <57,000 D <4.40 <5.60 <720 D <6.40 <14 <7.10 <8.20 <10
1,2,4-Tn methy Ibenzene 240,000 <5 50 <9.50 UJ <4.60 <4.40 6.5 TJ <240 D <5.80 <3,800 D 5.8 TJ <6,600 D <9.70 <57,000 D <4.40 <5.60 UJ <720 D <6.40 UJ <14 UJ <7.10 <8.20 UJ <10 UJ
1,2-Dichloroethane 2,000 <5.50 UJ <9.50 UJ <4 60 UJ <4 40 UJ <7.20 UJ <240 D <5.80 <3,800 D <12 <6,600 D <9 70 <57,000 D <4.40 <5.60 <720 D <6.40 5.6 T <7.10 <8.20 <10
1,3,5-Tnmethylbenzene (Mesitylene)12,000,000 <5.50 4.2 TJ <4 60 <4.40 <7.20 UJ <240 D <5 80 <3,800 D 11 TJ <6,600 D <9.70 <57,000 D <4.40 <5.60 UJ <720 D <6 40 UJ <14 UJ <7.10 <8.20 UJ <10 UJ
2-Chlorotoluene 23,000,000 <5.50 <9.50 UJ <4 60 <4.40 18 J <240 D <5.80 <3,800 D <12 UJ <6,600 D <9.70 <57,000 D <4.40 <5.60 UJ <720 D <6.40 UJ <14 UJ <7.10 <8.20 UJ <10 UJ
Acetone 670.000,000 <5.50 UJ 6.7 TJ 6.9 J <4.40 UJ 26 J <240 D 2.3 T <3,800 DUJ 170 <6,600 DUJ 2.9 TJ <57,000 DUJ 4.3 TJ <5.60 <720 DUJ <6.40 91 <7.10 <8.20
<10
Benzene 5,100 <5.50 <9.50 <4.60 <4.40 4.3 T <240 D <5.80 <3,800 D <12 <6,600 D <9.70 <57,000 D <4.40 <5.60 <720 D <6.40 <14 <7.10 <8.20 <10
Carbon disulfide 3,500,000 <5.50 <9.50 <4.60 <4.40 <7.20 <240 D 3.3 T <3,800 D 4.4 T <6,600 D <9.70 <57,000 D <4.40 <5 60 <720 D <6.40 <14 <7.10 <8 20 <10
Chloroethane NE <5.50 <9.50 <4.60 <4.40 <7.20 <240 D <5.80 <3,800 D <12 <6,600 D <9.70 <57,000 D <4.40 <5.60 <720 D <6.40 <14 <7.10 <8.20 <10
Chloroform 1,400 <5.50 <9.50 <4.60 <4.40 <7.20 <240 D <5.80 <3,800 D <12 <6,600 D <9.70 <57,000 D <4.40 <5.60 <720 D <6.40 <14 <7.10 <8.20 <10
cis-l,2-Dichloroethene 2,300,000 <5.50 15 <4 60 <4.40 18 <240 D 9.7 <3,800 D <12 <6,600 D 31 <57,000 D <4.40 <5.60 <720 D <6.40 8.1 T <7.10 <8.20 33
Ethylbenzene 25,000 <5.50 17 <4.60 <4.40 <7.20 UJ <240 D <5.80
4,700 D 30 27,000 D <9.70 140,000 D <4.40 <5.60 <720 D <6.40 <14 UJ <7.10 <8.20
<10 UJ
Isopropylbenzene (Cumene)9,900,000 <5.50 3.7 T <4.60 <4.40 17 J <240 D <5.80 1,100 TD 110 8,000 D <9.70 17,000 TD <4.40 <5 60 <720 D <6.40 <14 UJ <7.10 <8.20 <10 UJ
Methyl ethyl ketone (2-Butanone)190,000,000 <5.50 <9.50 <4.60 <4.40 7.6 <240 D <5.80 <3,800 D 31 <6,600 D <9.70 <57,000 D <4.40 <5.60 <720 D <6.40 25 <7.10 <8.20 <10
Methylene chloride 1,000,000 <5.50 <9.50 <4.60 <4.40 <7.20 <240 D <5.80 <3,800 D <12 <6,600 D <9.70 <57,000 D <4.40 <5.60 <720 D <6.40 <14 <7.10 <8.20 <10
n-Propylbenzene NE <5.50 <9.50 UJ <4.60 <4.40 2.3 TJ <240 D <5.80
<3,800 D 36 J 6,600 D <9.70 <57,000 D <4.40 <5.60 UJ <720 D <6.40 UJ <14 UJ <7.10 <8.20 UJ <10 UJ
Naphthalene 17,000 <5.50 UJ 5.3 TJ <4.60 UJ <4 40 UJ <7.20 UJ <240 D <5.80 <3,800 D <12 UJ <6,600 D <9.70 <57,000 D <4.40 <5.60 UJ <720 D <6.40 UJ <14 UJ <7.10 <8.20 UJ <10 UJ
m,p-Xy!ene (Sum of isomers)NE <11 110 <9.20 <8.70 8.2 TJ <480 D <12 66,000 D 26 110,000 D 28 1,200,000 D <8.90 <11 <1,400 D <13 <28 UJ <14 <16 <21 UJ
o-Xylene (1,2-Dimethylbenzene)2,800,000 <5.50 80 <4.60 <4.40 6.1 TJ <240 D <5.80 25,000 D <12 33,000 D 14 540,000 D <4 40 <5.60 <720 D <6.40 <14 UJ <7.10 <8.20 <10 UJ
Total Xylene (Sum of all 3 isomers)(c>2,500,000 nc 190 nc nc 14.3 nc nc 91,000 38 143,000 42 1,740,000 nc nc nc nc nc nc nc nc
Tetrachloroethene (PCE)100,000 4.7 T 14 <4.60 <4.40 18 J 370 D 6.9 <3,800 D <12 <6,600 D 12 34,000 TDJ <4 40 57 3.000 D <6 40 <14 UJ <7.10 30 210 J
Toluene 47,000,000 <5.50 8 T <4 60 <4.40 8.1 J <240 D <5 80 3,500 TD 5.2 T <6,600 D <9 70 40,000 TD <4.40 <5 60 <720 D <6 40 <14 UJ <7.10 <8 20 <10 UJ
Tnchloroethene (TCE)6,000 <5.50 13 <4.60 <4.40 34 140 TD 3.8 T <3,800 D 10 T <6,600 D 16 <57,000 D <4.40 3 T 310 TD <6.40 17 <7 10 3.1 T 82
Vinyl chloride 1,700 <5.50 UJ <9.50 UJ <4 60 UJ <4.40 UJ 2.6 TJ <240 D <5.80 <3,800 D <12 <6,600 D <9.70 <57,000 D <4 40 <5.60 <720 D <6.40 <14 <7.10 <8.20 <10
Herbicides (pg/kg)
2,4 DB 6,600,000 110 23 T <39 <350 D <390 DUJ 2,700 D 33 TJ 780 DJ <62 <44 65 140 <40 11,000 D 250 <410 D <70 30 T <410 D <59
2,4,5-T (Tnchlorophenoxyacetic acid)8,200,000 <7.80 <11 3 T <71 D <79 DUJ <74 D <8.80 230 DJ 17 <8.90 7.3 T 24 J <8.20 <84 D 23 J <83 D 10 TJ <10 <83 D <12
2,4-D (Dichlorophenoxvacetic acid)9,700,000 <38 <56 <39 <350 D <390 DUJ <370 D <44 <470 D 78 <44 28 T 90 <40 <410 D 34 T <410 D <70 <49 <410 D <59
Dalapon 25.000.000 <38 <56 <39 <350 D <390 DUJ <370 D <44
<470 D 630 380 <49 <43 <40 <410 D <63 <410 D <70 <49 <410 D <59
Dicamba 25,000,000 <7.80 <11 <8 <71 D <79 DUJ <74 D <880 <96 D <13 UJ 51 J <10 UJ <8 70 UJ <8.20 <84 D <13 <83 D <14 <10 <83 D <12
Dichloroprop NE <38 <56 <39 <350 D <390 DUJ <370 D <44 <470 D <62 57 <49 <43 <40 <410 D <63 <410 D <70 <49 <410 D <59
Dinoseb 820,000 <7.80 <11 <8 <71 D <79 DUJ <74 D <8 80 <96 D <13 <8.90 52 <8.70 <8.20 <84 D 65 <83 D <14 9.5 T <83 D <12
Pentachlorophenol 4,000 35 T 150 T <130 <1,200 D <1,300 DUJ 140 TD <150 20,000 DJ 38 T <150 16 T 570 <130 430 TD 89 T 27 TD <230 85 T <1,400 D 16 T
Silvex (2,4,5-TP)6.600,000 <7.80 <11 <8 <71 D <79 DUJ <74 D <8 80 330 DJ <13 <8.90 <10 11 <8 20 <84 D <13 <83 D <14 <10 <83 D <12
May 2015 EPA Regions 3,6, and 9 Limiting Industrial Soil Regional Screening Levels (carcinogenic target risk of 10"6 or noncancer with hazard index of 1, whichever is lower) Reference www.epa.gov/region9/superfund/prg
<b) The focused shallow soil investigation was designed to assess the extent of shallow soil contamination discovered at MW-33D during drilling operations in October 2011; shallow soil analytical results for MW-33D are included here for re
tc) Total xylene was calculated by summing laboratory results for m,p-xylene and o-xylene, data recorded below reporting limits (i.e., <9,700) were excluded from the summation.
«•)
Analyte not detected; however, the reporting limit is greater than the industrial soil screening level (due to nece
Concentration detected above the industrial soil screening level
Mg/kg Ug/kg micrograms per kilogram MCL Maximum contaminant level
mg/1 mg/I milligrams per liter na not analyzed
Bold Bold Bolded result indicates positively identified compound nc not calculated
-_Not scheduled NE not established
D D Sample dilution required for analysis, reported values reflect the dilution.R Associated quality control did not meet acceptance criteria
E E Data are estimated. Result exceeded calibration range, no dilution was analyzed.T Analyte was positively identified but the reported concentration is estimated, reported concentration is less than the reporting limit, but greater than the method detection limit
J J Data are estimated due to associated quality control data UB Analyte considered not detected based on associated blank data
M M Possible matrix effect UJ Potential low bias, possible false negative
Table B-3. 2013 Focused Shallow Soil Investigation Results
TABLE A-l
FOCUSED SHALLOW SOIL INVESTIGATION ANALYTICAL RESULTS - MAY 2013
WASATCH CHEMICAL SITE, SALT LAKE CITY, UTAH
(Page 4 of 4)
Source: Table A-1. Focused Shallow Soil Investigation Analytical Results - May 2013 Wasatch Chemical Site, Salt Lake City, Utah From MWH-Stantec. 2017. Human Health Risk Assessment for Shallow Soils in the Focused Investigation Area at the Wasatch Chemical Site, Salt
Lake City, Utah. August 28.
Sample Identification ES-01(b)EX-02(b)EX-04 EX-05 EX-07(b)EX-08(b)EX-09(b)EX-11(b)MW-06 MW-20(b)MW-23(b)MW-24A MW-25 MW-30 MW-34 PZ-1 PZ-3 Biodegradation
Date Collected 4/26/2022 4/26/2022 4/26/2022 4/26/2022 4/27/2022 4/28/2022 4/27/2022 4/27/2022 5/2/2022 5/3/2022 5/3/2022 5/3/2022 4/28/2022 4/27/2022 5/2/2022 5/3/2022 4/28/2022 Indicator
Analyte/ Parameter (Units)
Volatile Organic Compounds (µg/l)Analytical Method
Tetrachloroethene (PCE)5 SW8260B 0.16 T <1.0 <1.0 <1.0 1.6 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 na
Trichloroethene (TCE)5 SW8260B 7.1 19 <1.0 0.24 T 3.1 <1.0 0.11 T 0.74 T 0.17 T 0.36 T <1.0 <1.0 <1.0 1.0 0.19 T <1.0 <1.0 detection
1,1-Dichloroethene (1,1-DCE)7 SW8260B 0.12 T 3.3 0.84 T 6.4 0.13 T <1.0 1.2 4.5 3.0 1.4 <1.0 <1.0 <1.0 4.7 <1.0 <1.0 <1.0 detection
cis-1,2-Dichloroethene (cis-1,2-DCE)70 SW8260B 7 180 D 22 110 D 7.3 <1.0 25 280 D 34 J+24 <1.0 <1.0 <1.0 84 1.1 <1.0 <1.0 detection
trans-1,2-Dichloroethene (trans-1,2-DCE)100 SW8260B 0.53 T 9.0 5.7 94 0.53 T <1.0 6.3 150 D 8.5 15 <1.0 <1.0 <1.0 1.7 0.40 T <1.0 <1.0 detection
Vinyl Chloride (VC)2 SW8260B 3.0 46 <1.0 3.1 1.4 <1.0 0.17 T 460 D 1.5 12 <1.0 <1.0 <1.0 26 J-<1.0 <1.0 <1.0 detection
Pesticides (µg/l)
Pentachlorophenol (PCP)1 SW8151A <0.5 8.3 D ----<0.5 0.14 T --<0.5 ------------------na
Geochemical Parameters
pH (standard units)na field measurement 6.71 6.77 6.86 6.88 7.09 7.35 7.02 7.07 6.98 6.95 7.11 6.96 7.00 6.76 6.86 6.82 6.96 5 to 9(c)
Oxidation-Reduction Potential (mV)na field measurement -119.2 -60.2 -44.2 21.4 -129.6 82.7 -25.1 -152.4 -37.5 -12.6 -99.7 -108.9 -13.9 -22.6 -40.3 -52.5 -65.5 <50(c)
Dissolved Oxygen (mg/l)na field measurement 0.55 0.82 0.44 0.52 0.77 0.89 0.88 0.88 0.22 0.09 0.40 0.51 0.29 1.04 0.12 0.56 0.95 <0.5(c)
Nitrate (mg/l)10 E300.0 <0.1 0.178 1.47 <0.1 1.19 9.82 D 0.231 <0.1 <0.1 1.13 J <0.1 D,UJ <0.1 UJ <0.1 <0.1 <0.1 <0.1 UJ <0.1 <1(c)
Nitrite (mg/l)1 E300.0 <0.2 D <0.5 D <0.5 D <0.5 D <0.5 D <1 D <0.5 D <2 D <0.5 D < 1 D <2 D,UJ <0.1 UJ <0.2 D <2 D <0.1 <0.1 UJ <0.2 D >1
Iron II (mg/l)(a)na Hach 8146 3.32 2.98 0.46 0.1 0.48 0.97 0.97 0.52 2.86 2.11 0.86 3.27 0.32 1.99 1.10 1.45 2.13 >1(c)
Sulfate (mg/l)na E300.0 24.2 D 826 D 465 D 908 D 85.8 D 500 D 884 D 1110 D 692 D 637 D 496 D 52.6 D 379 D 865 D 366 D 279 D 2190 D <20(c)
Sulfide, total (mg/l)na E376.2 0.422 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 0.0497 T <0.1 <0.1 0.0640 T 0.0502 T 0.0654 T 0.0550 T 0.182 0.0156 T 0.0916 T >1(c)
(a)Iron II was measured in the field using Hach kits; Samples > 3.00 mg/l exceed the maximum reading of the Hach Kit.
(b)Scheduled to be sampled annually, during spring rounds only.
(c) From Technical Protocol for Evaluating Natural Attenuation of Chlorinated Solvents in Groundwater , USEPA, 1998.
(d) This chemical is a designated "indicator chemical" for the Site. The "most prevalent, mobile, persistent, and toxic compounds" found at the Site during remedial investigation activities in the late 1980s were selected and presented in the Site Record of Decision (USEPA, 1991) as Site indicator chemicals.
Laboratory results highlighted in yellow are greater than the analyte's MCL.
--Not analyzed
na Not applicable
NS Not sampled
MCL Regulatory drinking water maximum contaminant level
mV millivolt
µg/l micrograms per liter
mg/l milligrams per liter
Bold Geochemical parameters shown in bold indicate conditions are conducive to biodegradation of chlorinated compounds.
D Sample dilution required for analysis; reported values reflect the dilution.
J+Value was estimated due to associated quality control data, biased high. The surrogate percent recovery associated with the analysis was greater than the upper control limit.
J-Value was estimated due to associated quality control data, biased low.
J Result is estimated due to associated quality control data.
T Analyte was positively identified but the reported concentration is estimated; reported concentration is less than the reporting limit, but greater than the method detection limit.
UJ Potential low bias, possible false negative.
MCL Purpose and/or Interpretation
Indicator chemical(d)
Analytical Results Natural Attenuation Assessment
Indicator chemical(d)
Optimal range for reductive pathway
Reductive pathway possible
Reductive pathway possible
Reductive pathway possible
Evidence of nitrate reduction
Reductive pathway possible
At higher concentrations may compete with reductive pathway
Evidence of sulfate reduction
Indicator chemical(d); degradation product of PCE
Indicator chemical(d); degradation product of TCE
Degradation product of TCE
Degradation product of TCE
Degradation product of DCEs
Table B-4. Groundwater Monitoring Results – April-May 2022
TABLE 4
SHALLOW GROUNDWATER SAMPLING RESULTS AND NATURAL ATTENUATION INDICATORS
APRIL AND MAY 2022
WASATCH CHEMICAL SITE, SALT LAKE CITY, UTAH
Source: Table 4. Shallow Groundwater Sampling Results and Natural Attenuation Indicators April and May 2022 Wasatch Chemical Site, Salt Lake City, Utah From Stantec, 2022d. Wasatch Chemical Site Progress Report No. 117. October.
Notes
Sample Identification MW-31D MW-32D MW-33D
Screened Interval (feet bgs)38 - 48 46 - 56 35 - 45
Date Collected 5/2/2022 4/28/2022 5/2/2022
Analyte/ Parameter (Units)
Volatile Organic Compounds (µg/l)Analytical Method
Tetrachloroethene (PCE)5 SW8260B <1.0 <1.0 <1.0 Indicator chemical(b)
Trichloroethene (TCE)5 SW8260B <1.0 <1.0 <1.0 Indicator chemical(b)
1,1-Dichloroethene (1,1-DCE)7 SW8260B <1.0 <1.0 <1.0 Indicator chemical(b)
cis-1,2-Dichloroethene (cis-1,2-DCE)70 SW8260B <1.0 <1.0 0.91 T
trans-1,2-Dichloroethene (trans-1,2-DCE)100 SW8260B <1.0 <1.0 <1.0
Vinyl Chloride (VC)2 SW8260B <1.0 <1.0 0.31 T
Geochemical Parameters
pH (standard units)na field measurement 7.75 7.36 7.66
Oxidation-Reduction Potential (mV)na field measurement -24.6 -85.3 -47.9
Dissolved Oxygen (mg/l)na field measurement 0.41 0.31 0.30
Iron II (mg/l)(a)na Hach 8146 0.06 0.07 0.23
(a)Iron II was measured in the field using Hach kits.
bgs below ground surface
MCL Regulatory drinking water maximum contaminant level
mg/l milligrams per liter
mV millivolt
T
µg/l micrograms per liter
MCL
Analytical Results
(b)This chemical is a designated "indicator chemical" for the Site. The "most prevalent, mobile, persistent, and toxic compounds" found at the Site during remedial
investigation activities in the late 1980s were selected and presented in the Site Record of Decision (USEPA, 1991) as Site indicator chemicals.
Analyte was positively identified but the reported concentration is estimated; reported concentration is less than the reporting limit, but greater than the
method detection limit.
Table B-4. Groundwater Monitoring Results – April-May 2022
TABLE 5
DEEPER GROUNDWATER ZONE 1 SAMPLING RESULTS
APRIL AND MAY 2022
WASATCH CHEMICAL SITE, SALT LAKE CITY, UTAH
Source: Table 5. Deeper Groundwater Zone 1 Sampling Results April and May 2022 Wasatch Chemical Site, Salt Lake City, Utah From Stantec, 2022d. Wasatch Chemical Site Progress
Report No. 117. October.
TABLE 6
GROUNDWATER SAMPLING RESULTS FOR WELLS COMPLETED IN DEEPER ZONES 2, 3 AND 4
APRIL AND MAY 2022
WASATCH CHEMICAL SITE, SALT LAKE CITY, UTAH
Notes
Sample Identification MW-35D2 MW-36D2 MW-37D2 MW-38D3 MW-39D4
Screened Interval (feet bgs) 81 - 91 80 - 90 78 - 88 118 - 128 147.8 - 157.8
Groundwater Zone Deeper Zone 2 Deeper Zone 2 Deeper Zone 2 Deeper Zone 3 Deeper Zone 4
Date Collected 4/29/2022 4/29/2022 4/29/2022 4/29/2022 4/29/2022
Analyte/ Parameter (Units)
Volatile Organic Compounds (µg/l)Analytical Method
Tetrachloroethene (PCE)5 SW8260B <1.0 <1.0 <1.0 <1.0 <1.0 Indicator chemical(b)
Trichloroethene (TCE)5 SW8260B <1.0 <1.0 <1.0 <1.0 <1.0 Indicator chemical(b)
1,1-Dichloroethene (1,1-DCE)7 SW8260B <1.0 <1.0 <1.0 <1.0 <1.0 Indicator chemical(b)
cis-1,2-Dichloroethene (cis-1,2-DCE)70 SW8260B <1.0 <1.0 <1.0 <1.0 <1.0
trans-1,2-Dichloroethene (trans-1,2-DCE)100 SW8260B <1.0 <1.0 <1.0 <1.0 <1.0
Vinyl Chloride (VC)2 SW8260B <1.0 <1.0 <1.0 <1.0 <1.0
Geochemical Parameters
pH (standard units)na field measurement 7.96 6.99 7.94 6.77 7.73
Oxidation-Reduction Potential (mV)na field measurement -191.1 -121.9 -146.1 -70.1 -45.5
Dissolved Oxygen (mg/l)na field measurement 0.90 0.13 0.12 0.13 0.26
Iron II (mg/l)(a)na Hach 8146 0.10 0.30 0.05 0.04 0.16
(a)Iron II was measured in the field using Hach kits.
MCL Regulatory drinking water maximum contaminant level
bgs below ground surface
µg/l micrograms per liter
mg/l milligrams per liter
mV millivolt
(b)The "most prevalent, mobile, persistent, and toxic compounds" found at the Site during remedial investigation activities in the late 1980s were selected and presented in the Site Record of Decision (USEPA, 1991) as
Site indicator chemicals.
MCL
Analytical Results
Table B-4. Groundwater Monitoring Results – April-May 2022
Source: Table 6. Groundwater Sampling Results For Wells Completed in Deeper Zones 2, 3 and 4 April and May 2022 Wasatch Chemical Site, Salt Lake City, Utah From Stantec, 2022d. Wasatch
Chemical Site Progress Report No. 117. October.
Monitoring
Location Constituent of Concern
Drinking
Water MCL
(µg/l)
Mean
(µg/l)
Standard
Deviation
(µg/l)
Upper
Confidence
Limit(a)
Lower
Confidence
Limit(a)
Exceeds
MCL(b)Trend(c)Indication Recommendation
EX-02 Pentachlorophenol (μg/L)1 5.35 3.04 7.89 2.81 Yes No Stability Evaluate Alternate Performance Standard or Approach(d)
EX-02 Trichloroethene (μg/L)5 53.0 60.4 160 11.0 Yes No Stability Evaluate Alternate Performance Standard or Approach(d)
EX-02 Vinyl Chloride (μg/L)2 66.0 25.9 87.6 44.4 Yes No Stability Evaluate Alternate Performance Standard or Approach(d)
EX-05 1,1-Dichloroethene (μg/L)7 9.16 1.55 10.5 7.87 Yes No Stability Evaluate Alternate Performance Standard or Approach(d)
EX-05 Vinyl Chloride (μg/L)2 4.83 1.63 6.18 3.47 Yes No Stability Evaluate Alternate Performance Standard or Approach(d)
EX-11 Vinyl Chloride (μg/L)2 360 138 476 245 Yes No Stability Evaluate Alternate Performance Standard or Approach(d)
MW-20 Vinyl Chloride (μg/L)2 6.75 2.80 9.09 4.41 Yes No Stability Evaluate Alternate Performance Standard or Approach(d)
MW-30 Vinyl Chloride (μg/L)2 43.1 15.1 55.7 30.5 Yes No Stability Evaluate Alternate Performance Standard or Approach(d)
Note: Analyses conducted for the eight most recent data points; refer to Appendix C for more detailed results and plots.
(a) Confidence limits determined using a 95% confidence level, in accordance with USEPA guidance (USEPA, 2009).
(b) For nontrending data sets, MCL exceedances were determined by comparing the lower confidence limit to the MCL; for trending data sets, the lower limit of the confidence band was compared to the MCL.
(c) Presence of significant trend determined using Mann-Kendall method, with 99% confidence level as indicated in the Site Consent Decree (U.S. District Court, 1991).
(d) Alternate Performance Standards are defined in the Site Consent Decree (U.S. District Court, 1991).
µg/l micrograms per liter
MCL maximum contaminant level
NA not applicable
1,1-DCE 1,1-dichloroethene
PCP pentachlorophenol
TCE trichloroethene
VC vinyl chloride
TABLE 7
SHALLOW GROUNDWATER STATISTICAL ANALYSIS RESULTS
FOR APRIL AND MAY 2022
DATA SETS DETERMINED TO BE STATISTICALLY ABOVE MCLs
Table B-4. Groundwater Monitoring Results – April-May 2022
Source: Table 7. Shallow Groundwater Statistical Analysis Results for April and May 2022 Data Sets Determined To Be Statistically Above MCLs From Stantec, 2022d.
Wasatch Chemical Site Progress Report No. 117. October.
14
COC
1991
ROD
Action
Levels
(µg/L)
Well Apr-17 Nov-17 Apr-18 Nov-18 May-19 Nov-19 April
2020b
November
2020c Apr-21 Nov-21
PCE 5 EX-02 0.59 T not
analyzed
29 not
analyzed
<1.0 not
analyzed
<1.0 not
analyzed
<1.0 not
analyzed
TCE 5
ES-01 20 not
analyzed
6.5 not
analyzed
42 not
analyzed
20 not
analyzed
0.66 not
analyzed
EX-02 160 J not
analyzed
26 not
analyzed
15 not
analyzed
31 not
analyzed
11 not
analyzed
EX-07 5.2 not
analyzed
5.8 not
analyzed
3.2 not
analyzed
4.1 not
analyzed
1.8 not
analyzed
EX-11 40 not
analyzed
26 not
analyzed
23J not
analyzed
15 not
analyzed
0.58T not
analyzed
1,1-DCE 7
EX-05 10 9.3 13 9.8 12 8.7 9.5 8.6 9.2 9.1
EX-11 12 not
analyzed
14 not
analyzed
5.9 not
analyzed
7.7 not
analyzed
5.9 not
analyzed
Vinyl
chloride --a
ES-01 8.6 not
analyzed
3.3 not
analyzed
19 not
analyzed
8.4 not
analyzed
0.31T not
analyzed
EX-02 72 not
analyzed
120 D not
analyzed
62 not
analyzed
60 D not
analyzed
39 not
analyzed
EX-05 5.8 4.2 7.7 6.2 7.6 4.6 5.7 4.1 4.6 2.7
EX-07 0.45 T not
analyzed
2.5 not
analyzed
1.1 not
analyzed
2.6 not
analyzed
2.6 not
analyzed
EX-11 340 D not
analyzed
510 D not
analyzed
260 D not
analyzed
400 D not
analyzed
490 D not
analyzed
MW-20 5.2 not
analyzed
5.8 not
analyzed
8.8 not
analyzed
8.1 not
analyzed
4.8 not
analyzed
MW-30 41 62 D 42 D 57 J 33 42 J 8.1 67 D 53 D 25
PCP 1
ES-01 1.6 not
analyzed
<0.50 not
analyzed
2 not
analyzed
<0.50 not
analyzed
<0.50 not
analyzed
EX-02 1.6 not
analyzed
2.4 D not
analyzed
2.8 D not
analyzed
6.4 D not
analyzed
10 DJ not
analyzed
Table B-5. Concentrations in Wells with Exceedances of MCLs 2017-2021
Table 7: Concentrations in wells with exceedances of MCLs in Shallow Groundwater, 2017 to 2021
Source:Table 7. Concentrations in wells with exceedances of MCLs in Shallow Groundwater, 2017 to 2021 From U.S. Environmental Protection Agency, 2022. Sixth Five-Year Review Report
for Wasatch Chemical Co. (Lot 6) Superfund Site, Salt Lake County, Utah. August.