Fifth Five-year Review Report for Kerr-Mcgee Chemical Corp. (soda Springs Plant) Superfund Site Caribou County Idaho


FIFTH five-year review report for

KERR-MCGEE CHEMICAL CORP. (SODA SPRINGS PLANT) SUPERFUND SITE

CARIBOU COUNTY, IDAHO



SEPTEMBER 2022

Prepared by
U.S. Environmental Protection Agency
Region 10
Seattle, Washington

CALVIN
TERADA

Digitally signed by

CALVIN TERADA
Date: 2022.09.10
21:12:39 -07'00'

10 September 2022

Calvin J. Terada, Division Director

Date

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Table of Contents

LIST 01 ABBREVIATIONS & ACRONYMS	3

I.	INTRODUCTION	5

Site Background	5

FIVE-YEAR REVIEW SUMMARY FORM	8

II.	RESPONSE ACTION SUMMARY	8

Basis for Taking Action	8

Response Actions	9

Status of Implementation	11

Systems Operations/Operation and Maintenance (O&M)	17

III.	PROGRESS SINCE THE PREVIOUS REVIEW	18

IV.	FIVE-YEAR REVIEW PROCESS	22

Community Notification, Community Involvement and Site Interviews	22

Data Review	24

Site Inspection	28

V.	TECHNICAL ASSESSMENT	29

QUESTION A: Is the remedy functioning as intended by the decision documents?	29

QUESTION B: Are the exposure assumptions, toxicity data, cleanup levels and RAOs used at the
time of the remedy selection still valid?	30

QUESTION C: Has any other information come to light that could call into question the
protectiveness of the remedy?	31

VI.	ISSUES/RECOMMENDATIONS	31

OTHER FINDING	32

VII.	PROTECTIVENESS STATEMENT	32

VIII.	NEXT REVIEW	32

APPENDIX A - REFERENCE LIST	A-l

APPENDIX B - SITE CHRONOLOGY	B-l

APPENDIX C - SITE BACKGROUND - WASTE AND WATER MANAGEMENT FEATURES.. C-l

APPENDIX D - SITE MAPS	D-l

APPENDIX E - PRESS NOTICE	E-l

APPENDIX F - INTERVIEW FORMS	1-1

APPENDIX G - SITE INSPECTION CHECKLIST	G-l

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APPENDIX II - SITE INSPECTION PHOTOS	Il-I

APPENDIX I - DATA REVIEW FIGURES AND TABLES	1-1

APPENDIX J - TRENDS IN COC CONCENTRATIONS IN GROUNDWATER	J-l

Tables

Table 1: Groundwater COC PSLs	10

Table 2: Summary of Planned ICs	15

Table 3: Protectiveness Determination/Statement from the 2017 FYR	19

Table 4: Status of Recommendations from the 2017 FYR	20

Table 5: Effect of Changes in Toxicity Values on ROD Cleanup Goal	31

Table B-l: Site Chronology	B-l

Table 1-1: 2021 Groundwater Monitoring Results	1-8

Table 1-2: 2021 Surface Water Monitoring Results	1-17

Figures

Figure 1: Site Vicinity Map	7

Figure 2: Detailed Site Map	14

Figure 3: Groundwater Plume Map	16

Figure D-l: Geologic Faults	D-l

Figure D-2: TCRA Removal Boundaries and Volumes	D-2

Figure D-3: Site Features and Historic Source Areas of Concern	D-3

Figure 1-1: LTM Groundwater and Surface Water Monitoring Network	1-1

Figure 1-2: 2021 Groundwater Elevations and Potentiometric Contours	1-2

Figure 1-3: October 2021 Arsenic Concentrations	1-3

Figure 1-4: October 2021 Lithium Concentrations	1-4

Figure 1-5: October 2021 Manganese Concentrations	1-5

Figure 1-6: October 2021 Molybdenum Plume	1-6

Figure 1-7: October 2021 Vanadium Plume	1-7

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LIST OF ABBREVIATIONS & ACRONYMS

AOC

Area of Concern

BHHRA

Baseline Human Health Risk Assessment

CERCLA

Comprehensive Environmental Response, Compensation, and Liability Act

CFR

Code of Federal Regulations

CMT

Continuous Multichannel Tubing

COC

Contaminant of Concern

COPC

Contaminant of Potential Concern

DRO

Diesel Range Organics

EPA

United States Environmental Protection Agency

FFS

Focused Feasibility Study

FIAB

Former Industrial Area Boundary

FYR

Five-Year Review

IC

Institutional Control

ICP

Institutional Control Plan

IDEQ

Idaho Department of Environmental Quality

IDWR

Idaho Department of Water Resources

KMCC

Kerr-McGee Chemical Corporation

LTM

Long-Term Monitoring

MAP

Magnesium Ammonia Phosphate

MCL

Maximum Contaminant Level

mg/kg

milligrams per kilogram

Hg/L

micrograms per liter

NCP

National Contingency Plan

NPL

National Priorities List

O&M

Operation and Maintenance

OU

Operable Unit

PRP

Potentially Responsible Party

PSL

Project Screening Level

RAO

Remedial Action Objective

RBPS

Risk-Based Performance Standard

RI/FS

Remedial Investigation/Feasibility Study

ROD

Record of Decision

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RPM

Remedial Project Manager

RSL

Regional Screening Level

SLERA

Screening-Level Ecological Risk Assessment

SRI

Supplemental Remedial Investigation

TBP

Tributyl Phosphate

TCRA

Time-Critical Removal Action

TDS

Total Dissolved Solids

TPH

Total Petroleum Hydrocarbons

UU/UE

Unlimited Use and Unrestricted Exposure

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I. INTRODUCTION

The purpose of a five-year review (FYR) is to evaluate the implementation and performance of a remedy
to determine if the remedy is and will continue to be protective of human health and the environment.
The methods, findings and conclusions of reviews are documented in FYR reports such as this one. In
addition, FYR reports identify issues found during the review, if any, and document recommendations to
address them.

The U.S. Environmental Protection Agency is preparing this FYR pursuant to the Comprehensive
Environmental Response, Compensation, and Liability Act (CERCLA) Section 121, consistent with the
National Contingency Plan (NCP) (40 Code of Federal Regulations (CFR) Section 300.430(f)(4)(ii)) and
considering EPA policy.

This is the fifth FYR for the Kerr-McGee Chemical Corp. (Soda Springs Plant) Superfund site (the Site).
The triggering action for this statutory review is the completion date of the previous FYR. The FYR has
been prepared because hazardous substances, pollutants or contaminants remain at the Site above levels
that allow for unlimited use and unrestricted exposure (UU/UE). The Site consists of one operable unit
(OU), which is addressed in this FYR.

The EPA remedial project manager (RPM) Zoe Lipowski led the FYR. Participants included Stan
Christensen from Idaho Department of Environmental Quality (IDEQ) and Johnny Zimmerman-Ward
and Alison Cattani from EPA support contractor Skeo. The environmental trust responsible for the
cleanup, Greenfield Environmental Multistate Trust, LLC (Multistate Trust), was notified of the
initiation of the FYR. The review began on 11/15/2021. Refer to Appendix A for additional resources
and to Appendix B for the Site's chronology of events.

Site Background

The Site is located about 1.5 miles north of the city of Soda Springs in Caribou County, Idaho, and
consists of approximately 547 acres of land on the east side of State Route 34 (Figure 1). Chemical
manufacturing began at the Site in 1963 and continued until 2009. From 1963 to 1999, Kerr-McGee
Chemical Corporation (KMCC) operated a vanadium production plant, generated liquid industrial
wastes, and stored them in unlined on-site ponds. The unlined holding ponds leaked chemicals into
groundwater beneath the Site. Site operations and waste disposal practices contaminated groundwater
beneath and downgradient of the Site. Secondary by-products such as fertilizer and cathode materials for
rechargeable batteries were also produced between 1997 and 2009. In 2005, KMCC created Tronox Inc.
(Tronox), a corporate "shell" company, and transferred the Site (and hundreds of other contaminated
sites) without the funds required for cleanup. KMCC then sold the most valuable oil and gas assets to
Anadarko Petroleum Corporation (Anadarko). Unable to pay for cleanup of the KMCC sites, Tronox
filed for bankruptcy in 2009. The U.S. Bankruptcy Court approved a Settlement Agreement in 2011 that
established several trusts, including the Multistate Trust, with limited funds to address only the most
pressing environmental actions. A federal lawsuit against Anadarko for fraudulent conveyance led to a
2015 court-approved settlement. Under the Anadarko Litigation Settlement, the Site received additional
funds which allowed the Multistate Trust to implement several environmental actions at the site. The
Multistate Trust has been responsible for implementing environmental investigations and actions since
2011.

The former industrial area of the Site covers about 180 acres in the northern part of the Site and is
currently unused. This area of the Site is fenced and consists of capped waste areas (West Waste
Repository, East Waste Repository, and the East Calcine Repository), monitoring wells, erosion control
measures and wastewater tanks. Historic waste features and buildings have been removed during
remedial actions (Figure 2). The remaining areas of the former industrial area are used for agriculture or

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remain undeveloped as scrub-shrub habitat. The former industrial area of the Site is bordered on the
south and southeast by agricultural cropland owned by the Multistate Trust and on the west by the
Monsanto Corporation phosphate processing plant across State Route 34.1 Monsanto Corporation also
owns the property to the north and northeast of the former industrial area. A fertilizer packaging facility
called the Evergreen facility is located southwest of the Site.

The Site is located within Idaho's Bear River Basin. The Site lies in a valley at approximately 6,000 feet
above sea level. The valley is bordered by northwest trending mountain ranges reaching about 8,000 feet
above sea level. Natural springs are important hydrologic features of the basin and emerge to the ground
surface at several locations as a result of discharge from the underlying groundwater aquifer. Formation
Spring Creek is north of the Site and emanates from Formation Spring. Ledger Creek is a partially
ephemeral creek originating from several springs located east of the Site that traverses the southeastern
portion of the Site and eventually discharges into the Bear River to the south. The Ledger Creek
drainage south of the Site is a marshy wetland with various seeps and springs, indicating that shallow
groundwater discharges to the drainage in that area. Finch Spring is a particularly important surface
water feature and is one of several seeps and springs located south of the Site. There is a hydraulic
connection between the Site and Finch Spring, as evidenced by historical surface water sample results
with elevated site contaminant concentrations, indicating groundwater beneath the Site is a source of
water that discharges in and near Finch Spring. Further south, Big Spring flows into Big Spring Creek
and the Bear River; this spring has also shown detections of some site contaminants, indicating
migration from the Site and/or other industrial or waste disposal locations to the spring.

The principal regional groundwater formation is the Blackfoot Basalt aquifer, which consists of an upper
unconfined surficial aquifer in the upper basalt flows and scoria layers, and a semi-confined multi-
layered carbonate-rich aquifer in the lower basalt flows and scoria cones. Groundwater at the Site occurs
predominantly as an interconnected fracture system throughout the Blackfoot Basalt, with depths to
groundwater beneath the Site generally ranging from 25 to 65 feet below ground surface. A limited area
of saturated alluvium occurs on the eastern portion of the Site. Groundwater flow and associated
contaminant transport from the Site is to the south-southwest and is controlled by north-south oriented
faults (Figure D-l in Appendix D). Past volcanic activity and its lingering geothermal activity has
caused numerous springs and seeps where groundwater daylights in the Soda Springs region. As a result,
groundwater flowing underneath the Site discharges to seeps, springs, and surface water bodies located
within the Finch Creek, Little Springs Creek, and Big Springs Creek drainages.

The municipal water supply for the city of Soda Springs comes from springs located near the Site.
Formation Spring is located northeast of the Site and is upgradient, and Upper and Lower Ledger
Springs are located to the south and downgradient of the Site (Figure 1-1). The municipal water supply
springs are sampled as part of the Site's Long-Term Monitoring (LTM) program. The city water supply
is not impacted by the Site's contamination and multiple lines of evidence indicate that the water supply
will not be impacted if nearby groundwater pumping conditions change. There are also private domestic
wells in use near the Site. In 2014, Monsanto and the Multistate Trust conducted a domestic well survey
and water quality sampling event, which found no contamination in excess of screening levels is being
consumed. The Multistate Trust is in the process of conducting another well survey for inclusion in a
Petition for Area of Drilling Concern to the Idaho Department of Water Resources (IDWR), expected
Summer 2022.

1 The Monsanto Chemical Co. (Soda Springs Plant) is a Superfund Site. Site profile page located here:
https://www.epa.gov/superfund/monsanto-soda-springs.

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Approximate Site Boundary
Waste Repository

Former Industrial Plant
Boundary

X Spring Location

Kerr-McGee Chemical Corp.

(Soda Springs Plant) Superfund Site

City of Soda Springs, Caribou County, Idaho

Disclaimer: This map and any boundary lines within the map are
approximate and subject to change. The map is not a survey. The map Is for
informational purposes only regarding the EPA's response actions at the
Site. Sources: Esri. HERE. Garmin. SafeGraph, GeoTechnologies, Inc.
METl/NASA. USGS. Bureau of Land Management, EPA. NFS. USDA.
Maxar. the 2017 FYR Report, the 2019 LTM Sampling and Analysis Plan
and the 2019 O&M Plan.

7

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FIVE-YEAR REVIEW SUMMARY FORM

SITE IDENTIFICATION

Site Name: Kerr-McGee Chemical Corp. (Soda Springs Plant)

EPA ID: IDD041310707

Region: 10

State: Idaho

City/County: Soda Springs/Caribou

NPL Status: Final

Multiple OUs?

No

Lead agency: EPA

Has the Site achieved construction completion?

Yes

REVIEW STATUS

Author name: Zoe Lipowski, with additional support provided by Skeo

Author affiliation: EPA Region 10

Review period: 11/15/2021 - 9/25/2022

Date of site inspection: 4/26/2022

Type of review: Statutory

Review number: 5

Triggering action date: 9/25/2017

Due date (fiveyears after triggering action date): 9/25/2022

II. RESPONSE ACTION SUMMARY
Basis for Taking Action

Due to significant uncontrolled releases of contaminated process water to groundwater in 1981 and
1989, EPA added the Site to the National Priorities List (NPL) on October 4, 1989. Under EPA's
oversight, KMCC conducted site characterization activities from 1991 through 1994. In 1995, KMCC
completed a Remedial Investigation and Feasibility Study (RI/FS).

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Based on the 1995 RI/FS and associated risk assessment, the primary sources of the groundwater
contamination were the leaching of industrial wastewaters from unlined ponds, predominantly the
Scrubber Pond, S-X Pond, and the East Calcine Repository into groundwater (Figure 2 shows these
former unlined ponds). The primary pathway of concern at the Site was potential human ingestion of
groundwater. Human health risk was also associated with incidental ingestion of or direct contact with
roaster reject material, known to have high vanadium concentrations. The 1995 Record of Decision
(ROD) designated arsenic, manganese, molybdenum, vanadium, tributyl phosphate (TBP) and total
petroleum hydrocarbons (TPH) as the contaminants of concern (COCs) in groundwater. Human health
risks were not identified based on direct contact with surface water.

The 1995 ecological risk assessment did not find substantial ecological receptor risks from the Site.
Subsequent to the baseline ecological risk assessment, KMCC evaluated potential impacts to Finch
Pond, located one mile from the Site. Finch Pond sediments were sampled in 1995 to evaluate whether
molybdenum or vanadium have accumulated in sediments, resulting in potential increased risk to
waterfowl and other water birds via the food chain pathway. Based on the results, EPA determined that
the likelihood of significant ecological effects was low and no impacts were identified.

Response Actions

EPA signed the ROD for the Site on September 28, 1995, and amended it on July 13, 2000.

The 1995 ROD designated the remedial action objectives (RAOs) for the Site. The 2000 ROD
Amendment did not change the RAOs. The RAOs include the following:

• Prevent the transport of COCs from facility sources to groundwater; transport may result in COC
concentrations in groundwater exceeding risk-based concentrations (RBCs) or Maximum
Contaminant Levels (MCLs) for drinking water.

• Prevent ingestion by humans of groundwater containing COCs that have concentrations
exceeding RBCs or MCLs.

• Prevent transport of COCs from groundwater to surface water in concentrations that may result
in exceedances of RBCs or MCLs in the receiving surface water body.

• Prevent the ingestion/direct contact with the roaster rej ect area material having vanadium
concentrations in excess of 14,000 milligrams per kilogram (mg/kg).

• Prevent the transport of COCs from the active calcine tailings area to the surrounding soils in
amounts that exceed the 95 percent upper threshold limit (UTL) concentration of the background
soils.

The ultimate goal of the remedial action is to restore groundwater impacted by site sources to meet all
RBCs for COCs (other than arsenic) and the MCL for arsenic. The MCL (for arsenic) and the RBCS (for
all other COCs) are the established site-specific project screening levels (PSLs) for COCs at the Site
(Table 1).

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Table 1: Groundwater COC PSLs

Groundwater COC

1995 ROD PSL (jig/L)a

Vanadium

260

Molybdenum

180

Tributyl Phosphate

180

Total Petroleum Hydrocarbons

730

Manganese

180

Arsenic

50b

Notes:

a. Except for arsenic, the PSLs are risk-based concentrations established at the
time of the 1995 ROD to correspond to a hazard quotient of 1 for non-
carcinogens and a 1 x 10"6 level for carcinogenic risks.

b. National Primary Drinking Water Regulations MCL at the time of the ROD,
however the current Arsenic MCL is 10 ng/L.

Hg/L - micrograms per liter

The 1995 ROD included the following remedy components:

• Elimination of uncontrolled liquid discharges from the Site by replacing unlined ponds with
lined ponds.

• Excavation and reuse/recycling of buried calcine tailings (by using calcine to manufacture
fertilizer on site for an eight-year period).

• Excavation and disposal of S-X Pond and Scrubber Pond solids into lined ponds on site.

• In-place capping of windblown calcine and roaster reject material.

• Semiannual groundwater monitoring to determine the effectiveness of source control.

• Establishment of institutional controls (deed restrictions, limited site access, well restrictions
and/or wellhead protection) in affected areas downgradient of the former industrial area to
prevent ingestion of groundwater for as long as the groundwater exceeds the risk-based
concentrations.

The 1995 ROD contained a provision whereby the remedy and/or performance standards are to be re-
evaluated should contaminant levels in groundwater cease to decline and/or remain constant at levels
higher than the remediation goal over some portion of the plume. This provision was not changed in the
2000 ROD Amendment.

As part of the overall site strategy, although not part of the selected remedy, KMCC developed a waste
minimization/treatment plan to eliminate liquid discharges to groundwater from the facility within two
years. The plan included the following:

• Construction of new lined ponds to contain the main source of groundwater contamination (S-X
raffinate that discharged to leaking unlined ponds).

• Construction and operation of a phosphoric acid plant to consume scrubber water and calcine
tailings to produce phosphoric acid, ammoniated phosphate, and gypsum fertilizers as
marketable products.

EPA signed a ROD Amendment on July 13, 2000. Instead of reusing calcine tailings and roaster reject
materials for use as fertilizer, the ROD Amendment called for containment of these materials. The
fertilizer process did not prove successful and the capping alternative for this waste material (which was

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included in the FS) was subsequently selected as part of the remedy for the Site. The final selected
remedy included capping of the calcine, roaster reject and rejected (off-specification) fertilizer. The
amended remedy also called for establishing institutional controls to restrict land use to ensure the
capped area will not be disturbed.

On September 22, 2016, EPA approved a change in the sampling frequency for the Site from semi-
annual to annual in accordance with an EPA memorandum documenting a non-significant change to the
ROD. Historical data demonstrated that long-term data trends were still evident with an annual
monitoring frequency.

EPA signed an Action Memorandum on January 22, 2018, for the Time-Critical Removal Action of the
10-Acre Pond. The potential release of water and sediment from the 10-Acre Pond represented a
significant potential exposure risk to human health and the environment.

Status of Implementation

EPA and KMCC entered into a Consent Decree on August 21, 1997, in which KMCC agreed to
implement the remedies specified in the 1995 ROD.

Remedial actions taken as part of the implementation of the 1995 ROD and the 2000 ROD Amendment
are summarized below (Figure 2). Appendix C provides additional information about the historic source
areas and remedial components created as part of the remedial actions.

• Reclamation of the S-X Pond after the solids were moved to an on-site, double-lined and capped
landfill (West Waste Repository)2 and the liquids were moved to two lined ponds (East and West
5-Acre Ponds) (1996).

• Construction of the additional double-lined, 10-Acre Pond (1997).

• Installation of a baghouse system to eliminate the wet-scrubber and process water discharge,
reclamation of the Scrubber Pond after moving the solids to the West Waste Repository and
moving liquids to two lined ponds (East and West 5-Acre Ponds) (1997).

• Installation of a cap at the East Calcine Repository over the windblown calcine, roaster reject,
reject fertilizer and active calcine tailings (2001).

• Reclamation of the East and West 5-Acre Ponds with contents placed in the 10-Acre Pond
(2004).

• Consolidation and off-site disposal of residual waste from the manufacturing plants (2015-2016).

Although not required by the 1995 ROD or 2000 ROD Amendment, the vanadium plant and fertilizer
plants were demolished in 2002 and 2003, respectively.

The initial remedial activities resulted in consistent and substantial decrease in groundwater
contamination. By about 2007, the rate of improvement began to slow. Groundwater COC concentration
trend graphs are provided in Appendix J. In 2009, Tronox filed for bankruptcy. In 2011, ownership and
environmental liabilities were transferred to the Multistate Trust. The majority of the funding to perform
additional activities at the Site was not available until 2015 and 2016 when money from the Anadarko
Litigation Settlement resulted in additional funding for remediation. Since receiving funding, the
Multistate Trust, under oversight of EPA and in consultation with IDEQ, conducted additional site
investigations as summarized below.

2 This landfill has also been referred to as the "RCRA Landfill" in various site documents. There is no RCRA permit for the
Site; however, the term "RCRA Landfill" has historically been used because this waste repository was reportedly designed
and constructed to meet RCRA Subtitle D design standards. This area is currently referred to as the West Waste Repository.

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Supplemental Remedial Investigation (SRI)

The Multistate Trust conducted the SRI in several phases from 2015 through 2018, including a Phase I
SRI, a Phase II SRI and the 2018 SRI. The Site was divided into separate and distinct exposure areas:
on-Site (Industrial area and Lower Field) and off-Site (b) (6) Property, Soda Springs (groundwater
only), Big Spring Creek, Ledger Creek, and Unnamed Stream). The Multistate Trust summarized the
results in the 2019 SRI Report. The SRI was performed to fill identified data gaps and to achieve the
following objectives:

•	Phase I SRI - investigate and characterize possible additional sources of site-related COCs
within the former facility and augment and expand the existing groundwater monitoring well
network.

•	Phase II SRI - further investigate sources of site-related COCs, expand the existing monitoring
well network to better define groundwater gradients, physical and anthropogenic effects on area
groundwater, and the extent of contamination, and investigate city of Soda Springs water supply
sources for potential site-related COC impacts.

•	2018 SRI - further characterize the nature and extent of primary site-related contamination
(residual waste) and secondary site-related contamination (COCs transported by leaching or
infiltration of waste liquids from former unlined ponds and ditches).

The current monitoring well network is shown on Figure 1-1. The original monitoring well network
(wells KM-1 through KM-13 and KM-15 through KM-19) was installed in 1991-1992; additional KM-
series wells were installed as part of the Phase I SRI (KM-21 through KM-33, installed in 2015) and
Phase II SRI (KM-34 through KM-48, installed in 2016-2017). The 2018 SRI included installation of 48
continuous multichannel tubing (CMT) wells, with each well containing multiple ports targeting
groundwater at specific depths. The CMT well network was installed along multiple transects within and
downgradient of the Site, including a background well; the Former Industrial Area Boundary (FIAB)
Western Edge transect; the AOC-1 transect; the FIAB transect; the Evergreen transect; the East 6th
Street North transect; the East Hooper Avenue transect; and the Bear River / Big Spring area (Figure 1-1
in Appendix I).

In 2018 and 2019, the Multistate Trust implemented the 10-Acre Pond Time-Critical Removal Action
(TCRA), which included removal of all liquid, sludge, liner, security fencing and snow fencing from the
10-Acre Pond area.3 The construction of a new waste repository was an integral component of the 10-
Acre Pond TCRA. Excavation of calcine from the West Calcine Repository was integrated into the 10-
Acre Pond TCRA for source removal, for mixing with and drying of liquids and sludges from the 10-
Acre Pond, and for the calcine material to serve as a cushion base layer for construction/demolition
waste to be placed in the repository. A new lined repository (East Waste Repository) was constructed to
contain the waste materials from the 10-Acre Pond TCRA, the demolition debris from site buildings,
and materials from the removal of the West Calcine Repository/S-X Pond, North and South Industrial
Landfills and South Scrap Areas. The TCRA removal areas are shown in Figure D-2 in Appendix D.
These activities were conducted to remove known primary sources of contaminants, with the objective
of minimizing the site-related COCs leaching to groundwater. The Multistate Trust conducted
confirmation sampling and the results were compared to EPA's Regional Screening Levels (RSLs) for
residential soils (390 mg/kg). The results were less than EPA's residential RSLs. Concentrations in

3 KMCC constructed the 10-Acre Pond in 1997 to contain liquids and solids from vanadium processing and vanadium
production wastes from closure of former unlined process ponds at the Site. Although the 10-Acre Pond was lined, there was
a concern that the existing liner was reaching its functional life expectancy.

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surface soil confirmation samples were greater than the protection of groundwater screening levels.
Regrading of the surface topography of the former industrial area of the Site was also completed in 2019
to direct drainage and surface water runoff away from the source areas.

The SRI Report was issued in 2019, and included the following primary conclusions:

• Molybdenum and vanadium are the only two site-derived, persistent COCs in groundwater that
have migrated vertically and laterally in groundwater downgradient of the Site.

• Arsenic and manganese were historically mobilized via reductive dissolution due to site
operations involving organic compounds. As the organic compounds have degraded and
conditions have become more oxidizing over time, both arsenic and manganese have become
less mobile, and concentrations have decreased in groundwater.

• Lithium was added as a contaminant of potential concern (COPC). Although site activities
increased concentrations of lithium in groundwater beneath the Site, the lack of correlation
between off-site elevated lithium and off-site elevated molybdenum and vanadium suggests off-
site exceedances are not site-related and instead may be naturally occurring.

• Two distinct molybdenum and vanadium groundwater plume cores emanate from the Site
(Figure 3), largely due to historical releases from three areas of concern (AOCs; Figure 2):
AOC-1, AOC-2, and AOC-3.

• Near-surface primary waste (pond residuals and calcine) and secondary waste (shallow
subsurface overburden) are the most significant sources responsible for COC leaching to
groundwater. These waste materials were removed to a significant extent as part of site
demolition activities and the 10-Acre Pond TCRA. Along with site regrading activities to
minimize infiltration, these actions are expected to substantially reduce COC concentrations in
groundwater over time. The estimated time to reach cleanup levels for molybdenum is up to 50
years less in the zone between the FIAB Transect and the Evergreen Transect, and approximately
12 years less at the East 6th North Street Transect compared to pre-TCRA Site conditions.

• The city of Soda Springs water supply is not currently affected by site-related COCs and is not
expected to be impacted in the future due to preferential plume flow paths and physical barriers
to plume migration from the Site to the water supply springs (Figure 1-1).

• Other non-site-related sources potentially contribute to groundwater impacts downgradient from
the Site.

LTM Program

As part of the remedy, long-term groundwater monitoring at the Site has been conducted to assess the
effectiveness of source control in achieving groundwater performance standards. Monitoring of water
levels and water quality in monitoring wells and selected springs was conducted by Tronox in 1995 and
then on a semi-annual basis through 2010, as required by the 1995 ROD. Following the establishment of
the Multistate Trust, groundwater monitoring occurred on a semi-annual basis from 2011 to 2015. In
2016, EPA approved a change in the sampling frequency for the Site from semi-annual to annual in
accordance with an EPA memorandum documenting a non-significant change to the ROD. Long-term
groundwater and surface water monitoring has continued at the Site on an annual or semi-annual basis.

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Disclaimer: This map and any boundary lines within the map are
approximate and subject to change The map is not a survey. The map Is
for informational purposes only regarding the EPA's response actions at
the Site. Sources: Earthstar Geographies, Maxar, the 2017 FYR Report,
the 2019 SRI Report and the 2019 LTM Sampling and Analysis Plan

Kerr-McGee Chemical Corp. Superfund Site (Soda Springs Plant)

City of Soda Springs, Caribou County, Idaho

Last Modified. 5/2/2022

Figure 2: Detailed Site Map

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"Boiler Slowdown,
Pond (Reclaimed),

East Calcine
Repository

VanadiumcRlant

,_k y y.x xl ..
(Demolished)

10-Acre Pond
(Reclaimed)

West Calcine
Repository
(Reclaimed)

I :S-XtRdndy
(Reclaimed)

Limestone Settling
and'storm wa terj
'Ponds (Reclaimed)

P>;6crobtie^l°p?y|
Reclaimed)'^

South Industrial
Landfill Area
(Reclaimed)

14

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Institutional Control (IC) Review

The ROD requires institutional controls such as deed restrictions, access restrictions, well restrictions
and/or wellhead protection to prevent human ingestion of contaminated groundwater and wells from
being developed as sources of drinking water within the area of contamination. Additionally,
institutional controls are required in the ROD Amendment to prohibit activities on the capped area that
could result in an unacceptable exposure to the COCs.

The Multistate Trust is planning to implement an on-site institutional control in the form of a deed
notice after the upcoming FFS and ROD Amendment are finalized. This deed notice will restrict land
and groundwater use and prohibit activities on the capped areas. In the meantime, the Multistate Trust
owns the Site and no sale or lease is permitted without approval by EPA and IDEQ. Portions of the Site
are fenced and access is restricted.

Groundwater is not used as drinking water at the Site. The Multistate Trust, EPA, IDEQ and the IDWR
are in the process of preparing a Petition for Area of Drilling Concern to prohibit the installation of
drinking water wells in the area of off-site groundwater contamination. The petition will be submitted to
IDWR for its review and consideration. In the meantime, the Multistate Trust has conducted a domestic
well survey and no private wells have been identified within the area of groundwater contamination.
Furthermore, the Multistate Trust has confirmed through communications with the city that clean water
provided by the city to its residents, and to select locations outside of city limits, is available to all
properties that are located geographically within the area of site-related groundwater contamination.
Lastly, the Multistate Trust added the city water supply to the ongoing LTM program to confirm that the
water supply is not impacted by site contamination. See Table 2 for a summary of the planned
institutional controls.

Table 2: Summary of Planned ICs

Media, Engineered
Controls and Areas
That Do Not
Support UU/UE
Based on Current
Conditions

ICs
Needed

ICs Called
for in the
Decision
Documents

Impacted
Parcels

IC
Objective

IC Instrument Planned

Soil

Yes

Site Parcels

Prevent disturbance
of the capped areas.

Deed Notice (planned for
9/25/2025)

On-Site Groundwater

Yes

Site Parcels

Prevent dermal
contact with and
ingestion of,
contaminated
groundwater.

Deed Notice (planned for
9/25/2025)

Off-Site
Groundwater

Yes

Area with
contaminated
groundwater
(see Figure 3)

Prevent ingestion of
contaminated
groundwater and
wells from being
developed as sources
of drinking water
within the area of
contamination

Petition for Area of
Drilling Concern (planned
for 9/25/2025)

-------
Figure 3: Groundwater Plume Mai

West Waste
Repository

East Waste
Repository

East Calcine
Repository

I	I Approximate Site Boundary

I	 Parcel Boundary

I I Waste Repository

Typical Extent of Vanadium
f__ ! Concentrations Greater than
RSL (86 (jg/L)

Typical Extent of Molybdenum
Concentrations Greater than
RSL (100 ng/L)

Kerr-McGee Chemical Corp.

(Soda Springs Plant) Superfund Site

City of Soda Springs, Caribou County, Idaho

I	1	1

0	1,000	2,000 Feet

Disclaimer This map and any boundary lines within the map are
approximate and subject to change. The map is not a survey. The map
Is for informational purposes only regarding the EPA's response actions
at the Site. Sources: Earth star Geographies, Maxarthe 2017 FYR
Report, the 2019 O&M Plan, the 2019 Long Term Monitoring Plan and
the Caribou County Parcel Viewer.

16

-------
Systems Operations/Operation and Maintenance (O&M)

The Multistate Trust conducts site O&M under the 2019 O&M Plan (superseding previous iterations
from 2017 and 2018). The objectives of the O&M Plan specify the following actions:

• Conduct O&M for site remedy features.

• Maintain site security.

• Complete miscellaneous site maintenance.

• Manage fire risk for the Site.

• Define the means of reporting site O&M activities.

Routine O&M started in 1996. O&M of the Site includes inspections of the following:

• West Waste Repository.

• East W aste Repository.

• East Calcine Repository/Scrubber Pond Area.

• Monitoring Well Network.

• Wastewater Tanks.

Site inspections include inspecting the capped waste areas, fencing, signage, erosion control measures,
groundwater monitoring wells and wastewater storage tanks. Periodic pumping of sumps to address
water accumulation in the East and West Waste Repositories is also performed. The water is stored in
on-site wastewater storage tanks for subsequent off-Site disposal. Outside of normal O&M activities,
there have not been any issues noted in the previous five years.

West Waste Repository

The West Waste Repository includes a primary and secondary bottom liner, leachate collection system
and engineered cover. The multi-layer cap is vegetated and the area is surrounded by a 6-foot chain-link
fence. Maintenance includes monthly visual inspection of the cap, monthly depth to water measurement
in the landfill sump, yearly water removal from the sump and monthly visual inspection of the signage,
fencing and locks.

East Waste Repository

The East Waste Repository includes a primary and secondary bottom liner, leachate collection system,
gas migration system and a primary and secondary liner cover system. The multi-layer cap is vegetated
and the area is surrounded by a 6-foot chain-link fence. Maintenance includes monthly visual inspection
of the cap, monthly depth to water measurement in the landfill sump, yearly water removal from the
sump and monthly visual inspection of the signage, fencing and locks.

East Calcine Repository/Scrubber Pond Area

The East Calcine Repository is capped with a flexible membrane cover and geocomposite liner, subsoil
and vegetated topsoil. This area also includes the Scrubber Pond area. The East Calcine
Repository/Scrubber Pond area is surrounded by a 6-foot chain-link fence. Maintenance includes
monthly visual inspection of the cap and monthly visual inspection of the signage, fencing and locks.

Monitoring Well Network

Maintenance for all site monitoring wells includes quarterly visual inspection for damage or evidence of
tampering. Per the O&M Plan, any damaged monitoring wells are reported on the regular inspection
checklist and the Contract Project Manager is notified immediately to arrange for the wells to be
repaired.

-------
Inspection and maintenance of the groundwater monitoring well network is an element of site O&M.

In 2016, the sampling frequency for the Site was reduced from semi-annual to annual in accordance with
an EPA memorandum documenting a non-significant change to the ROD. Long-term groundwater and
surface water monitoring has continued at the Site on an annual or semi-annual basis since this change.
Details of the surface water and groundwater monitoring program for the Site are presented in the 2019
Groundwater and Surface Water LTM Sampling and Analysis Plan for the Site, and updated through
annual surface water and groundwater monitoring reports.

Other Site Features

Monthly inspections are also conducted of the four wastewater storage tanks, fencing, gates, signs and
remaining buildings on site.

III. PROGRESS SINCE THE PREVIOUS REVIEW

This section includes the protectiveness determination and statement from the previous FYR as well as
the recommendations from the previous FYR and the status of those recommendations (Table 3 and 4,
respectively).

18

-------
Table 3: Protectiveness Determination/Statement from the 2017 FYR

ou#

Protectiveness
Determination

Protectiveness Statement

Sitewide

Not Protective

The remedy for the Kerr-McGee Chemical Corporation (KMCC) Site is
currently not protective because of the following issues:

•	Potential ecological risks may exist from the migration of the COC
plume beyond the current Site boundary and potential presence of
high concentration source material located within the 10-Acre
Pond could affect groundwater quality and ecological receptors.

•	Institutional Controls have not been established or implemented
for locations downgradient of the industrial facility where COCs
exceed MCLs or risk-based groundwater performance standards
(including Trust owned properties). Plumes of COCs generated
from the Site have migrated significantly beyond the IC-controlled
property boundary onto private and city owned land into the town
of Soda Springs, contributing to the non-protective status of the
remedy.

•	Nature and extent of groundwater plumes of site-related COCs are
not well defined, and the monitoring well network is not adequate
to provide necessary information. In addition, groundwater and
surface water monitoring trends indicate the performance standard
will not be met in the foreseeable future.

The following actions need to be taken in order to ensure protectiveness:

•	Finalize the draft screening level assessment, including the
identification of additional data gaps and characterize the nature of
the source material in the 10-Acre Pond. Evaluate pond contents
for COC concentration and distribution. Assess its potential as a
source of groundwater contamination, including data from
downgradient monitoring wells, and evaluate whether COC
concentrations could be high enough to pose an unacceptable risk
to ecological receptors such as, ducks, geese, and local terrestrial
birds.

•	Develop an ICP [Institutional Control Plan] and implement
institutional controls governing groundwater use at locations
downgradient of the industrial facility where COCs are known to
exceed MCLs or risk-based groundwater performance standards.

•	Finalize the multi-phased supplemental remedial investigation,
including the identification of additional data gaps and evaluate
whether additional remedial actions are needed.

19

-------
Table 4: Status of Recommendations from the 2017 FYR

ou#

Issue

Recommendations

Current
Status

Current
Implementation
Status Description

Completion

Date (if
applicable)

Sitewide

Potential

Finalize the draft

Completed

In 2018, the 10-Acre

3/11/2020



ecological risks

screening level



Pond was removed





may exist from

assessment,



via a TCRA. In





the migration of

including the



2020, the Multi state





the COC plume

identification of



Trust finalized the





beyond the

additional data gaps



BHHRA and the





current Site

and characterize the



SLERA. The SRI did





boundary and

nature of the source



not identify any





potential presence

material in the 10-



reason to change the





of high

Acre Pond.



original conclusion





concentration

Evaluate pond



that there was no





source material

contents for COC



unacceptable risk to





located within the

concentration and



ecological receptors.





10-Acre Pond

distribution. Assess









could affect

its potential as an









groundwater

active source for









quality and

groundwater









ecological

contamination









receptors.

(including data











from downgradient











monitoring wells),











and evaluate











whether COC











concentrations











could be high











enough to pose an











unacceptable risk to











ecological receptors











(such as, ducks,











geese, and local











terrestrial birds).







20

-------
Table 4: Status of Recommendations from the 2017 FYR







Current
Status

Current

Completion

ou#

Issue

Recommendations

Implementation

Date (if







Status Description

applicable)

Sitewide

Institutional

Develop an ICP and

Ongoing

The Multi state Trust

Not



Controls have not

implement



will implement on-

applicable



been established

institutional



site institutional





or implemented

controls governing



controls after the





for locations

groundwater use at



upcoming ROD





downgradient of

locations



Amendment. With





the industrial

downgradient of the



regard to off-site





facility where

industrial facility



institutional controls,





COCs exceed

where COCs are



the Multistate Trust,





MCLs or risk-

known to exceed



EPA, IDEQ and





based

MCLs or risk-based



IDWR are in the





groundwater

groundwater



process of preparing





performance

performance



a Petition for Area of





standards

standards.



Drilling Concern to





(including Trust





prohibit installation





owned





of drinking water





properties).





wells in the area of





Plumes of COCs





off-site groundwater





generated from





contamination. An





the Site appear to





institutional control





have migrated





plan (such as an





significantly





ICIAP) will be





beyond theIC





developed to ensure





controlled





the effectiveness of





property





ICs in the long term.





boundary onto











private and city











owned land into











the town of Soda











Springs.









21

-------
Table 4: Status of Recommendations from the 2017 FYR

ou#

Issue

Recommendations

Current
Status

Current
Implementation
Status Description

Completion

Date (if
applicable)

Sitewide

Nature and extent

Finalize the multi-

Completed

The Multistate Trust

11/21/2019

of groundwater

phased

finalized the SRI

plumes of site-

supplemental

process with the

related COCs are

remedial

publication of the

not well defined,

investigation,

2019 SRI Report. In

and the

including the

2021, the Multistate

monitoring well

identification of

Trust submitted a

network is not

additional data gaps

draft FFS to EPA

adequate to

and evaluate

and IDEQ.

provide necessary

whether additional

information. In

remedial actions are

addition,

needed.

groundwater and

surface water

monitoring trends

indicate that

performance

standards will not

be met in the

foreseeable

future.

IV. FIVE-YEAR REVIEW PROCESS

Community Notification. Community Involvement and Site Interviews

A public notice was made available by newspaper postings in the Caribou County Sun, on December 16,
2021, and in the Idaho State Journal, on December 19, 2021, (Appendix E) that the FYR was underway
and invited the public to submit any comments to EPA. The results of the review and the report will be
made available at the Site's information repository (Soda Springs Public Library located at 149 South
Main Street, Soda Springs, ID 83276).

During the FYR process, interviews were conducted to document any perceived problems or successes
with the remedy that has been implemented to date. The interviews are summarized below. The
interview forms are provided in Appendix F.

The Multistate Trust participated in an interview and provided an overview of the extensive site
characterization work as well as remedial work that has occurred during this FYR period. The Multistate
Trust believes they have had a positive impact on the local community through local hiring, building
demolition and building donation, maintaining a fire break on-site to mitigate wildfire risk and ongoing
weed management at the Site. In addition, the Multistate Trust has facilitated beneficial reuse for some
areas of the Site including farming and leasing of several buildings on-site for storage (outside any area
of contamination). The Multistate Trust indicated that there is no current risk to human health since all
properties located in the vicinity of the groundwater contamination are on city water and the city water

-------
supply is sampled annually. The Multistate Trust works closely with the local government and
community stakeholders. Some community members have expressed frustration with the timeframe for
cleanup and would like to see the Site reused by a major industrial employer. The Multistate Trust also
acknowledged the support and leadership provided by EPA and IDEQ, which allowed the Site to
progress with the SRI and FFS process while concurrently implementing the TCRA, building
demolition, repository construction and site regrading.

Scott Rigby, O&M contractor for the Multistate Trust, stated that a lot has been accomplished at the Site
and the work has been done well and in a timely manner. Mr. Rigby reported that the Site is inspected
several times per week for security reasons and there have been no obvious issues.

Joel Gerhart, remedial action contractor for the Multistate Trust, indicated that cleanup progress during
the previous five years has been good. Historic and recent source removal activities should reduce the
groundwater exceedances; however, more monitoring is needed to further evaluate the degree of
reduction. Mr. Gerhart believes the current monitoring network and program is complete and resulting
dataset robust without collecting extraneous data. He believes that several more years of monitoring data
are needed to assess the effects of source removal.

Stan Christensen, IDEQ, reports a positive impression of the project. Mr. Christensen indicated that the
current remedy has not been adequate to remove and contain contamination. Groundwater impacts still
remain and areas off site are impacted by groundwater contamination. Mr. Christensen reported two
residents who inquired about contamination on their property. A resident with a groundwater well was
concerned it might be contaminated from the groundwater plume. Another property northeast of the Site
was concerned about soil contamination. In both instances, testing was conducted and no soil or
groundwater exceedances above the cleanup goals were found.

Bryce Somsen, Caribou County Commissioner, stated that he is well informed on the Site's activities
and remedial progress. Mr. Somsen indicated that the local paper, the Caribou County Sun, would be the
best way to provide information to the community and he would like to see some more information on
what types of reuse options would be appropriate for the Site. Mr. Somsen is specifically interested in a
solar farm as a reuse option at the Site.

Eric Hobson, Caribou County Director of Public Safety, stated that he is aware of the Site and is updated
and well informed on the Site's activities and remedial progress. The county is not aware of any local
regulations or changes in projected land use that would impact the Site. Mr. Hobson expressed concern
for reuse of the Site since a landfill was left on site.

Mitch Hart, Soda Springs City Council President, stated that he is aware of the Site and is well
informed. He expressed appreciation for the fact sheets, which are helpful for the local community. Mr.
Hart recommends using the Caribou County Sun, the local newspaper, to distribute information. Mr.

Hart indicated there have been no problems with unusual or unexpected activities at the Site. Mr. Hart
would like public outreach to continue on a regular basis and would like to see the Site put into
productive use as soon as possible.

A local resident, (b) (6) , indicated he is aware of

the Site and the history of remedial activities at the Site. He would also like the Site to be reused and
redeveloped as soon as possible. He stated that some residents are concerned about the water supply
wells and contamination. This resident suggested a summer public meeting to provide information. This
resident also supported putting information in the local newspaper.

Another local resident stated that he has a private well and has dealt with issues relating to a metallic
taste. He has done some sampling in the past but there is a lag time with getting results. EPA will work

-------
with this resident to determine if this well should be sampled. This resident feels that the Multistate
Trust has done a good job and has been aggressive with the cleanup activities in the previous five years.
This resident also indicated that the local newspaper is the best way to communicate with the
community. This resident would like to see more technical information pertaining to the Site. In terms of
reuse, Kelly Park near the Site is an attraction for hiking and skiing. Portions of the Site could be used
for open space.

Data Review

During this FYR period, the Multistate Trust collected additional data for the SRI and the FFS.

Appendix A lists the reports that were reviewed as part of this FYR. In addition to the SRI and FFS, the
Multistate Trust also conducted LTM, collecting groundwater and surface water data. The SRI findings
and the LTM data are summarized below.

SRI Findings

Data collected as part of the SRI included the following:

• Groundwater data from 48 multi-level wells to assess nature and extent of groundwater
contamination.

• Soil data from 27 soil borings.

• Surface water, sediment and fish tissue data from off-site water bodies to fill data gaps for
human health and ecological risk assessments.

The key results from the SRI were presented in the 2019 SRI Report and the 2019 FFS Data Collection
Technical Memorandum. Overall, the SRI found that groundwater is the major exposure pathway for
site COCs. Molybdenum and vanadium are the primary COCs mobilizing off-site above site PSLs. The
migration of other COCs (arsenic, manganese, lithium, TBP and TPH) is limited and concentrations of
metals outside the site boundary are likely naturally occurring. The SRI results also indicated there are
other potential sources of COCs beyond the site boundary (former Evergreen facility and the Monsanto
site). The SRI also concluded that the molybdenum and vanadium groundwater plumes were fully
delineated and the city of Soda Springs water supply sources are not impacted currently or anticipated to
be in the future (Figure 1-1).

Historical migration of groundwater COCs was reduced through remedial actions required in the
decision documents and the recent 10-Acre Pond TCRA. Remaining groundwater COCs are primarily
the result of leaching from residual materials; however, the SRI Report indicated that most of this mass
has been removed and groundwater quality is expected to improve though it may take over 120 years.

The Multistate Trust identified several primary pathways for groundwater plume migration along north-
south trending faults and associated fracture systems. This information was utilized in evaluating
potential remedial measures during the FFS process and will aid in the selection of a modified remedy in
a ROD Amendment.

Annual LTM

In response to recommendations made in the 2019 SRI Report, the LTM program was updated in 2019.
The groundwater and surface water monitoring networks are shown on Figure 1-1 in Appendix I.

Groundwater quality monitoring locations are sampled for arsenic, manganese, molybdenum, vanadium,
lithium, selenium, major cations and anions, total dissolved solids (TDS) and field parameters. A subset
of wells is sampled for the TBP and TPH-Diesel Range Organics (DRO). The monitoring well network
includes wells installed prior to the 1995 ROD and wells installed as part of the Phase I, Phase II and

-------
2018 SRIs. The 2018 SRI included installation of CMT wells, with each well containing multiple ports
targeting groundwater at specific depths.

Surface water locations selected for LTM water quality sampling include all six city water supply
locations (Spring A, Spring 1 [Lower Ledger], Spring 2, Spring 4, Spring 5 [Upper Ledger] and
Formation Spring) and four additional locations (Spring 3, Big Spring, Finch Spring and Kelly Pond).
Surface water locations are sampled for inorganic compounds, major cations, major anions, TDS and
field parameters. Metals and major cations are analyzed on the total (unfiltered) fraction for surface
water.

For this FYR, EPA reviewed the 2017, 2018, 2019, 2020 and 2021 Annual LTM Reports; this Data
Review focuses on the most recent report from 2021. LTM activities in 2021 consisted of an annual
spring/summer primary monitoring event conducted in June and a supplemental fall monitoring event
conducted in September and October. Figure 1-1 in Appendix I shows the groundwater and surface water
monitoring locations.

Prior to groundwater quality sampling activities, the Multistate Trust collected groundwater level
measurements at all locations during both the June and October 2021 events. The June 2021
groundwater level data was used to develop the most recent potentiometric map (Figure 1-2 in Appendix
I). This map includes concurrently collected Monsanto groundwater elevation data. The surface water
and spring elevations are also shown on the map due to the hydraulic connection between shallow
groundwater and surface water in the site area.

The south-southwest groundwater flow direction is depicted with flow arrows on Figure 1-2 and is
supported by the overall geometry of the site-related molybdenum and vanadium groundwater plumes,
indicated by the LTM data and by the evaluations presented in the 2019 SRI Report.

In 2021, based on input from EPA and IDEQ, the Multistate Trust added supplemental monitoring well
locations to allow for additional data evaluation. Table 1-1 in Appendix I provides the groundwater COC
concentrations in June and September-October 2021. The 2021 Annual Report provided figures showing
the lateral distribution of arsenic, lithium, manganese, molybdenum and vanadium in groundwater for
the 2021 LTM events, with groundwater plume maps presented for the primary site-related constituents
mobilizing off-site (molybdenum and vanadium). These figures are included as Figures 1-3 through 1-7
in Appendix I. In general, groundwater monitoring results are consistent with what was observed during
the SRI.

Arsenic

As shown in Table 1-1 and Figure 1-3, arsenic concentrations in October 2021 ranged from below
detection to 73.7 micrograms per liter (|ig/L) (in on-site well KM-08). During both 2021 LTM events,
exceedances of the arsenic PSL (50 ug/L) and MCL (10 |ig/L) were confined to on-site wells except for
off-site well KM-48 (MCL exceedance). As presented in the 2019 SRI Report, the off-site arsenic
exceedance observed at KM-48 is not believed to be site-related. Historical site operations mobilized
naturally occurring arsenic based on a change in redox state to more reducing conditions. Redox
conditions are becoming less reducing (more oxidizing) over time, thereby decreasing the mobility of
arsenic in groundwater. As a result, arsenic concentrations have declined significantly in groundwater
underlying the Site.

As reported in the 2021 Annual Report (Appendix J), arsenic concentration trends in groundwater are
largely stable or slightly decreasing, with no significant long-term trends indicated. Exceptions include
relatively significant decreases in wells T2-240-02 and -03, where arsenic concentrations have decreased
below the 10 [ig/L MCL since the initial sampling event in 2018. The highest concentration on-site well

-------
(T2-202-01) currently shows a decreasing arsenic trend, though T2-202-01 is still well above the
Arsenic MCL (120 ug/L in June 2021).

Lithium

Lithium was identified as a COPC during the 2019 SRI. Concentrations in 2021 have remained
consistent with previous observations. Lithium concentrations in October 2021 ranged from 6.2 to 1,900
|ig/L (background screening level is 131 |ig/L), with the highest concentration observed in on-site well
KM-8 (Table 1-1). Figure 1-4 shows the spatial distribution of lithium in groundwater. As reported in the
2019 SRI Report, due to the lack of correlation between off-site lithium and the primary site-related
COCs molybdenum and vanadium, the off-site lithium is primarily attributed to naturally-occurring
sources. Sampling for lithium began recently so there are no long-term trends for lithium.

Manganese

As shown in Table 1-1 and Figure 1-5, manganese concentrations in October 2021 ranged from below
detection to 3,010 |ig/L (in on-site well FFS-1). Exceedances of the manganese PSL (180 |ig/L) and
RSL (430 |ig/L) occur in both on-site and off-site wells. Manganese is commonly found in aquifer
solids, with the solubility and mobility of manganese directly related to groundwater redox conditions.
Historical Site operations mobilized naturally occurring manganese based on a change in redox
conditions in the vadose and saturated zones. Redox conditions have become more oxic over time,
thereby reducing the mobility of manganese in groundwater. As a result, manganese concentrations in
groundwater have declined significantly and should continue to decrease over time as organic
compounds released from the Site naturally degrade.

The manganese trend plots provided in the 2021 Annual Report (Appendix J) show mostly decreasing or
stable trends. Decreasing manganese concentrations can be indicative of increasingly oxidizing
groundwater conditions. Additional LTM data will allow for further evaluation of the decreasing
manganese concentration trends.

Molybdenum

Molybdenum is one of the two primary COCs migrating from on-site source areas to downgradient areas
off-site. Maximum molybdenum concentrations continue to be observed in on-site well KM-8 (26,500
|ig/L in October 2021). The molybdenum plume originates at the Site and extends south and southwest
into Soda Springs. Exceedances of the molybdenum PSL (180 |ig/L) and RSL (100 |ig/L) were reported
in groundwater as far south as well T2-238 (214 |ig/L in June 2021 and 230 |ig/L in October 2021).
Surface water sampling location Big Spring, near well T2-238, also slightly exceeded the molybdenum
RSL in June 2021 (101 |ig/L).

The general areal extent of the molybdenum plume is consistent with historical plume maps from the
previous LTM reports and the 2019 SRI Report. Figure 1-6 in Appendix I shows three distinct source
areas where molybdenum concentrations exceed 1,000 |ig/L. These areas are within or downgradient of
the three AOCs evaluated in the 2019 SRI Report.

The long-term molybdenum trends for wells with a longer period of record are generally characterized
with steep decreases during the initial monitoring events followed by a gradual shift to slightly
decreasing or stable. Overall, these wells are currently either at or near minimum concentrations for the
period of record. For the new wells installed during the SRI, trends are less clear. Additional LTM data
will allow for further evaluation of molybdenum trends.

-------
Vanadium

Vanadium is the other primary COC mobilized from the Site to downgradient off-site areas. The
maximum vanadium concentrations continue to be observed in on-site well T2-204-01 (213,000 |ig/L in
October 2021) located near AOC-1. The vanadium plume exceeding the RSL originates beneath the Site
and extends off-site to the south and southwest similar to the molybdenum plume. The highest vanadium
concentrations on site are observed near the former vanadium plant. Exceedances of the PSL (260 |ig/L)
and the RSL (86 |ig/L) extend to East Hooper Avenue. The vanadium plume does not extend as far
downgradient as the molybdenum plume likely due to significant natural attenuation via adsorption to
iron oxides within the aquifer, as opposed to molybdenum which behaves more conservatively (i.e.,
concentration decreases attributable largely to dilution and dispersion effects). The attenuation of
molybdenum and vanadium is discussed in more detail in both the 2019 SRI Report and in the draft FFS
Report.

The vanadium concentration trends are generally more variable with a mixture of increasing, decreasing
and stable trends. Vanadium concentration trend graphs are provided in Appendix J.

TBP and TPH

In accordance with the LTM Sampling and Analysis Plan, TBP and TPH-DRO were analyzed at a
limited number of groundwater sampling locations in 2021, focusing on wells at the downgradient
property boundary and wells that have previously shown detectable TBP concentrations. TBP was
detected above the PSL (180 |ig/L) in two wells in June 2021 and one well in October 2021, both of
which are located on site.

TPH-DRO was not detected above the PSL (730 |ig/L) in 2021. In 2020, the maximum TPH-DRO
concentrations occurred in on-site wells KM-8 in June (1,170 |ig/L) and T2-204-01 in October 2020
(1,020 |ig/L and 1,030 |ig/L in the sample-duplicate pair). In 2021, the maximum TPH-DRO
concentrations occurred in on-site well T2-217-02 (631 |ig/L in June and 622 |ig/L in October).

Surface Water

Surface water quality sampling was conducted at 11 locations in June and October 2021. (Spring A,
Spring 1 [Lower Ledger], Spring 2, Spring 4, Spring 5 [Upper Ledger] and Formation Spring, Spring 3,
Big Spring, Finch Spring, and Kelly Pond). Surface water monitoring locations are shown on Figure 1-1
in Appendix I. In addition to the 10 sites designated in the LTM SAP, one surface water location added
to the monitoring schedule during the October 2019 LTM event (Evergreen) was also sampled in June
2021. The Evergreen site was dry in October 2021 and no sample was collected.

Concentrations of total arsenic, manganese, molybdenum, vanadium and lithium in 2021 LTM surface
water samples are presented in Table 1-2 in Appendix I. Results for total molybdenum and vanadium in
surface water are also shown on the groundwater plume maps (Figures 1-6 and 1-7 in Appendix I). As
described in Table 1-2 in Appendix I, six of the surface water sampling locations are drinking water
sources for the city of Soda Springs (Spring A, Lower Ledger, Upper Ledger, Spring 2, Spring 4 and
Formation Spring). As observed during previous LTM events, concentrations of all COCs in June and
October 2021 were well below applicable drinking water screening levels (PSLs/RSLs/MCLs) at the six
drinking water source locations, with the primary site-related constituents showing concentrations
ranging from 1.3 to 1.6 (j,g/L for molybdenum and 0.52 to 1.1 [ig/L for vanadium (Table 1-2 in
Appendix I).

The non-drinking water sites sampled as part of LTM activities (Spring 3, Big Spring, Finch Spring,
Kelly Pond and Evergreen) also had COC concentrations below PSLs and MCL/RSLs in 2021, with the
exception of molybdenum at Big Spring in June 2021. The Evergreen site also shows molybdenum

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concentrations above background (83.5 |xg/L in 2021), but slightly below the RSL (100 |J.g/L). The 2021
molybdenum and vanadium concentrations at the Big Spring, Finch Spring and Evergreen sites are all
consistent with the spatial distribution of these contaminants observed in groundwater (Figures 1-6 and I-
7 in Appendix I), suggesting that these springs are surface discharge points for groundwater.

These surface water sampling locations were also evaluated as part of the 2020 SLERA. The results
indicated that no ecological risks were associated with the Site that require further evaluation or action.

As observed during past monitoring events, Kelly Pond molybdenum concentrations in 2021 (12.6 to
41.7 ng/L) were lower than Finch Spring, Big Spring and Evergreen, but higher than the other
spring/surface water sites. Vanadium concentrations in Kelly Pond (2 to 13 |J.g/L) were also lower than
Evergreen and Finch Spring, but slightly higher than other spring/surface water sites. Kelly Pond is in
the same drainage area and downstream of Finch Spring.

Molybdenum and vanadium trend plots show concentrations have been consistently below the PSLs and
RSLs at all sites except Big Spring, Finch Spring and Evergreen. The 2021 molybdenum and vanadium
concentrations at Evergreen were the minimum values observed to date at this location. Big Spring
molybdenum concentrations have stabilized near the RSL in the previous three years and vanadium
concentrations have been typically low at this location. Finch Spring concentrations have been
consistently decreasing and vanadium and molybdenum concentrations are well below PSLs and RSLs.

Site Inspection

The site inspection took place on 4/26/2022. Participants included: Zoe Lipowski, EPA RPM, Stan
Christensen and Nick Nielsen, IDEQ, Lars Peterson, Multistate Trust, and Alison Cattani and Johnny
Zimmerman-Ward from EPA's support contractor Skeo. The purpose of the inspection was to assess the
protectiveness of the remedy. The site inspection checklist and photos are included in Appendix G and
H, respectively.

Site inspection participants met at the office building located in the former industrial area of the Site.
The Site is secure with a locked gate. Mr. Peterson indicated there have not been any issues with
trespassing or unauthorized access on the Site. Participants observed earth-moving activities north of the
Site along Trail Creek Road. Mr. Peterson indicated Monsanto is building a railroad spur line in this
area. Participants inspected the fenced waste repositories including the West Waste Repository, East
Waste Repository and the East Calcine Repository. Participants observed several areas that had been
recently reseeded with native grasses. These areas correspond to the areas that were reclaimed as part of
the TCRA. Participants then inspected the former 10-Acre Pond which was well vegetated. The recently
completed drainage improvements were also observed. The inspection participants also observed the
agricultural areas directly south of the former industrial area. All monitoring wells were in good
condition and locked.

Site inspection participants then visited several surface water locations including the Formation Spring,
Evergreen Spring and the Upper and Lower Ledger Springs. Except for the Evergreen Spring, all surface
water was flowing. While water was present at the Evergreen Spring, it was not flowing and appeared
stagnant. This spring is located directly next to the operating Evergreen facility. During the inspection,
there were no issues observed that would impact future or current protectiveness.

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V. TECHNICAL ASSESSMENT

QUESTION A: Is the remedy functioning as intended by the decision documents?

Question A Summary:

No, the remedy is not functioning as intended by the 1995 ROD and the 2000 ROD Amendment. The
goal of the remedy was to restore impacted groundwater to meet PSLs by removal of site sources.
Remedial actions from 1997 through 2004 included reclamation of several wastewater ponds, creation of
on-site repositories, storage of contaminated material in lined ponds, and capping contaminated soils.
While initial results indicated groundwater concentrations were decreasing, the rate of decrease slowed
and additional investigations were needed to determine why concentrations were not reducing to the
PSLs. Starting in 2015 and 2016, the Multistate Trust, under oversight of EPA and in consultation with
IDEQ, completed site investigation activities and studies to fully characterize the extent of
contamination in support of the development of an FFS and ROD Amendment. Concurrently with these
investigation activities, the Multistate Trust also performed removal actions to reduce risk to human
health and the environment and remove a large amount of source material that was resulting in impacts
to groundwater on and off-site. There are currently two plumes (vanadium and molybdenum) extending
off-site and groundwater concentrations are well above PSLs. Molybdenum concentrations in the 2021
LTM groundwater samples ranged from 0.18 [ig/L to 26,500 (j,g/L in 2021. Altogether, 36% of the
molybdenum results obtained in 2021 exceeded the 180 (j,g/L PSL. The 2021 LTM data for vanadium
indicate a wide range of concentrations, from <0.27 [ig/L to 250,000 (j,g/L. The 260 [ig/L vanadium PSL
was exceeded in 29% of the samples. The Multistate Trust submitted a draft FFS to EPA and IDEQ in
2021 and anticipates it will be finalized in 2022. EPA will then select an amended remedy for the Site in
a ROD Amendment.

As part of the site investigation activities, the Multistate Trust determined that the city of Soda Springs
water supply is not currently impacted by site-related COCs and is not expected to be impacted in the
future due to preferential plume flow paths and physical barriers to plume migration from the Site to the
water supply springs. A 2014 domestic well survey confirmed that private wells are not currently
impacted by the Site. The Multistate Trust is in the process of conducting another well survey. This will
be completed in 2022.

The Multistate Trust is conducting O&M for the Site under the 2019 O&M Plan. Site inspections
include inspecting the capped waste areas and cover crops, fencing, signage, erosion control measures,
groundwater monitoring wells and wastewater storage tanks. Periodic pumping of sumps to address
water accumulation in the East and West Waste Repositories is also performed. During this FYR period,
all required O&M has been conducted and documented in monthly reports.

Institutional controls are not yet in place. On-site institutional controls are planned and will be
implemented after the ROD Amendment is issued. The Multistate Trust owns the property and any land
use change must be approved by EPA and IDEQ. Off-site groundwater institutional controls are also
planned in the form of a Petition for Area of Drilling Concern through IDWR. Based on information
obtained from the 2019 SRI Report, BHHRA and SLERA, there is no current human health or
environmental exposure to contamination on or off-site. The Multistate Trust has conducted a domestic
well survey and no private wells have been identified within the area of groundwater contamination and
has confirmed through communications with the city that clean water provided by the city to its
residents, and to select locations outside of city limits, is available to all properties that are located
geographically within the area of site-related groundwater contamination.

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QUESTION B: Are the exposure assumptions, toxicity data, cleanup levels and RAOs used at the time
of the remedy selection still valid?

Question B Summary:

No.

Since the ROD was issued, EPA has revised the MCL for arsenic from 50 |ig/L to a more stringent 10
|ig/L, therefore the ROD cleanup goal is no longer valid and needs to be updated. In addition, the
toxicity information has changed for manganese, TPH (evaluated as JP-5), tributyl phosphate, and
vanadium. The noncancer toxicity values for manganese and tributyl phosphate are higher than the
values used at the time of remedy selection. This means that acceptable exposure concentrations to
manganese and tributyl phosphate would be higher than those established on the ROD, and by definition
the ROD cleanup goals for these COCs remain protective. Noncancer toxicity values for vanadium are
lower, acceptable exposure concentrations associated would be lower than established in the ROD. EPA
substantially revised the toxicity assessments for total petroleum hydrocarbon fractions in 2009. TPH
characterized as JP-5 is evaluated using toxicity data for the TPH midrange aromatic fraction,
Additionally, EPA has established a cancer slope factor for tributyl phosphate based on its toxicity,
rather than radiological risk.

In addition to changes in toxicity values, EPA has substantially revised the way it evaluates dermal and
inhalation exposures, and has revised its recommended exposure parameters for these pathways. To
assess the effect of these changes and whether the ROD cleanup values remain protective, they were
compared to the most recent (May 2022) tapwater RSLs, which represent acceptable concentrations for
household use. The RSLs also incorporate updated toxicity values, and updated guidance for assessing
dermal and inhalation exposures. Where the ROD cleanup goal is based on a noncancer health effect, the
noncancer hazard quotient (HQ) is calculated as the ratio of the cleanup goal and the current RSL based
on a noncancer endpoint. Where the cleanup goal is based on a cancer risk, that can be calculated at the
ratio of the cleanup goal and the RSL based on a 1 x 10"6 cancer risk, as shown in the following
equations:

ROD cleanup goal - noncancer

HQ =

RSL noncancer

, , , ROD cleanup goal - cancer ,

Risk = £-2 xlO

RSL cancer

The results of this analysis are shown in Table 5. The cleanup goals for tributyl phosphate and vanadium
are within EPA's acceptable risk range, and the cleanup goal remains protective. The estimated HQ for
TPH using the toxicity value for JP-5 is evidence that the ROD cleanup goal may no longer be
protective. However more information is needed regarding the composition of TPH in groundwater at
the site to make a more definitive determination. This will be done through the upcoming remedy
decision process.

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Table 5: Effect of Changes in Toxicity Values on ROD Cleanup Goal

coc

ROD Cleanup Goal
(Hg/L)

RSL

Basis

Hazard Quotient/
Cancer Risk3

TPH (as JP-5)

730

5.5

nc

133

Tributyl Phosphate

180

5.2

ca

3.E-05

Vanadium

260

86

nc

3

a - values in scientific notation represent estimated cancer risk
nc - non-cancer
ca - cancer

QUESTION C : Has any other information come to light that could call into question the protectiveness
of the remedy?

No other information has come to light that could call into question the protectiveness of the remedy.

VI. ISSUES/RECOMMENDATIONS

Issues/Recommendations

OU(s) without Issues/Recommendations Identified in the FYR:

None

Issues and Recommendations Identified in the FYR:

OU(s):

Sitewide

Issue Category: Remedy Performance

Issue: The current groundwater remedy is not functioning as intended by the
1995 ROD and the 2000 ROD Amendment and cleanup levels are no longer
valid. Additional monitoring activities and evaluations have been conducted
during this FYR period to support the selection of an amended remedy.

Recommendation: Finalize the FFS, select a proposed remedy, identify
protective cleanup levels and issue the ROD Amendment to document the
updated remedy and implement.

Affect Current
Protectiveness

Affect Future
Protectiveness

Party
Responsible

Oversight Party

Milestone Date

No

Yes

EPA

EPA

9/25/2024

31

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OU(s):

Sitewide

Issue Category: Institutional Controls

Issue: Institutional controls are not yet in place for land use and groundwater.

Recommendation: Implement institutional controls.

Affect Current
Protectiveness

Affect Future
Protectiveness

Party
Responsible

Oversight Party

Milestone Date

No

Yes

Multistate Trust

EPA

9/25/2025

OTHER FINDING

One additional recommendation was identified during the FYR. This recommendation does not affect
current and/or future protectiveness.

• Consider providing Site updates in the local newspaper, the Caribou County Sun.
VII. PROTECTIVENESS STATEMENT

Sitewide Protectiveness Statement

Protectiveness Determination:

Short-term Protective

Protectiveness Statement:

The remedy currently protects human health and the environment because there is no exposure to
contaminated groundwater or soil. However, in order for the remedy to be protective in the long-term,
the following actions need to be taken: finalize the FFS and issue the ROD Amendment to document
and implement the updated remedy and institutional controls.

VIII. NEXT REVIEW

The next FYR Report for the Kerr-McGee Chemical Corp. (Soda Springs Plant) Superfund site is
required five years from the completion date of this review.

32

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APPENDIX A - REFERENCE LIST

2018 Groundwater and Surface Water Long-Term Monitoring Report Kerr-McGee Chemical Corp. -
Soda Springs Plant Superfund Site Soda Springs, Caribou County, Idaho. Prepared by Hydrometrics,
Inc. May 2019.

2019 Groundwater and Surface Water Long-Term Monitoring Report Kerr-McGee Chemical Corp. -
Soda Springs Plant Superfund Site Soda Springs, Caribou County, Idaho. Prepared by Hydrometrics,
Inc. July 2020.

2020 Groundwater and Surface Water Long-Term Monitoring Report Kerr-McGee Chemical Corp. -
Soda Springs Plant Superfund Site Soda Springs, Caribou County, Idaho. Prepared by Hydrometrics,
Inc. April 2021.

10-Acre Pond TCRA, Final After Action Report, Kerr-McGee Chemical Corp. Soda Springs Plant
Superfund Site, Soda Springs, Caribou County, Idaho. Prepared by Pioneer Technical Services, Inc.
April 2019.

10-Acre Pond TCRA, Final After Action Report Addendum, Kerr-McGee Chemical Corp. Soda Springs
Plant Superfund Site, Soda Springs, Caribou County, Idaho. Prepared by Pioneer Technical Services,
Inc. October 2019.

Action Memorandum for a Time-Critical Removal Action for the 10-Acre Pond at the Kerr-McGee
Chemical Corp. Soda Springs Plant Superfund Site, Soda Springs, Caribou County, Idaho. EPA Region
10. January 2018.

Annual Comprehensive Report of Groundwater and Surface Water Quality, 2017 Monitoring, Kerr-
McGee Chemical Corporation - Soda Springs Plant Superfund Site, Soda Springs, Idaho. Prepared by
Tetra Tech, Inc. May 2018.

Baseline Human Health Risk Assessment, Volume I, Kerr-McGee Chemical Corp. - Soda Springs Plant
Superfund Site, Soda Springs, Idaho. Prepared by Hydrometrics, Inc. and TRC. June 2020.

December 2020 Monthly Progress Report Kerr-McGee Chemical Corp. - Soda Springs Plant Superfund
Site, Soda Springs, Idaho. Prepared by Multistate Trust. January 2021.

Evaluation of Anticipated Impacts of 10-Acre Pond Time Critical Removal Action Kerr-McGee
Chemical Corp. - Soda Springs Plant Superfund Site Soda Springs, Idaho. Prepared by Haley &

Aldrich. July 2021.

Final Groundwater and Surface Water Sampling and Analysis Plan, Kerr-McGee Chemical Corporation
Soda Springs Superfund Site, Soda Springs, Idaho. Prepared by Tetra Tech, Inc. October 2017.

First FYR Report for Kerr-McGee Chemical Corp. (Soda Springs) Superfund Site, Caribou County,
Idaho. EPA Region 10. August 2002.

Fourth FYR Report for Kerr-McGee Chemical Corp. (Soda Springs) Superfund Site, Caribou County,
Idaho. Prepared by CH2M. September 2017.

Groundwater and Surface Water Long-Term Monitoring Sampling and Analysis Plan, Kerr-McGee
Chemical Corporation Soda Springs Plant Superfund Site, Soda Springs, Idaho. Prepared by
Hydrometrics, Inc. September 2019.

A-l

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Investigations of Molybdenum in Groundwater and Surface Water at Former Tronox/Kerr-McGee
Facility, Soda Springs, Idaho. EPA Region 10. June 2017.

Investigations of Selenium in Groundwater and Surface Water at the Monsanto/P4 Soda Springs Plant
Soda Springs, Idaho. EPA Region 10. June 2017.

July 2021 Monthly Progress Report Kerr-McGee Chemical Corp. - Soda Springs Plant Superfund Site,
Soda Springs, Idaho. Prepared by Multistate Trust. August 2021.

June 2020 Monthly Progress Report Kerr-McGee Chemical Corp. - Soda Springs Plant Superfund Site,
Soda Springs, Idaho. Prepared by Multistate Trust. July 2020.

Monitored Natural Attenuation Evaluation Kerr McGee Chemical Corp. - Soda Springs Plant Superfund
Site Soda Springs, Idaho. Prepared by Hydrometrics, Inc. July 23, 2021.

October 2021 Monthly Progress Report Kerr-McGee Chemical Corp. - Soda Springs Plant Superfund
Site, Soda Springs, Idaho. Prepared by Multistate Trust. November 2021.

Operations and Maintenance Plan, Version 1.0, Kerr-McGee Chemical Corporation, Soda Springs Plant
Superfund Site. Prepared by Hydrometrics, Inc. February 2018.

Operations and Maintenance Plan, Version 2.0, Tronox/Kerr-McGee Chemical Corporation, Soda
Springs Plant Superfund Site. Prepared by Hydrometrics, Inc. June 2019.

Record of Decision Amendment, Kerr-McGee Chemical Corp. (Soda Springs Plant), EPA ID:
IDD041310707, OU1. EPA Region 10. July 13, 2000.

Record of Decision, Kerr-McGee Chemical Corp. (Soda Springs Plant), EPA ID: IDD041310707, OU1.
EPA Region 10. September 28, 1995.

Results of Supplemental Data Collection in Support of Focused Feasibility Study Kerr-McGee Chemical
Corp. - Soda Springs Plant Superfund Site Soda Springs, Idaho. Prepared by Haley & Aldrich, Inc.
October 2019.

Screening-Level Ecological Risk Assessment, Kerr-McGee Chemical Corp. - Soda Springs Plant
Superfund Site. Prepared by Hydrometrics Inc. and TRC. March 2020.

Second FYR Report for Kerr-McGee Chemical Corp. (Soda Springs) Superfund Site, Caribou County,
Idaho. Prepared by US Army Corps of Engineers. September 2007.

Supplemental Remedial Investigation Phase I Summary and Phase II Work Plan, Former Tronox/Kerr-
McGee Chemical Corporation Superfund Site, Soda Springs, Idaho. Prepared by Tetra Tech, Inc. August
2016.

Supplemental Remedial Investigation Report, Kerr-McGee Chemical Corp. Soda Springs Plant
Superfund Site, Soda Springs, Idaho. Prepared by Haley & Aldrich. November 2019.

Third FYR Report for Kerr-McGee Chemical Corp. (Soda Springs) Superfund Site, Caribou County,
Idaho. Prepared by CH2MHILL. September 2012.

A-2

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APPENDIX B - SITE CHRONOLOGY
Table B-l: Site Chronology

Event

Date

KMCC operated a vanadium production facility

1963 - 1999

Significant uncontrolled releases of contaminated process water to
groundwater from the unlined ponds

1981 and 1989

EPA placed the Site on the NPL

October 4, 1989

KMCC conducted the RI

1991 - 1994

KMCC completed the FS and EPA issued the ROD

1995

KMCC reclaimed the S-X Pond, moved solids to the West Waste
Repository, moved liquids to East and West 5-Acre Ponds

1996

EPA and KMCC entered into a Consent Decree in which KMCC agreed
to implement the remedies specified in the 1995 ROD.

August 21, 1997

KMCC constructed the 10-Acre Pond

1997

KMCC closed the Scrubber Pond after moving solids to the West Waste
Repository and moving liquids to the East and West 5-Acre Ponds

1997

EPA issued the ROD Amendment

2000

KMCC installed a cap on the East Calcine Repository

2001

KMCC demolished the Vanadium Plant

2002

EPA issued the first FYR

2002

KMCC demolished the Fertilizer Plant

2003

KMCC reclaimed the East and West 5-Acre Ponds and placed contents in
the 10-Acre Pond

2004

KMCC purchased an adjacent property to the southwest

2004

KMCC created Tronox

2005

EPA issued the second FYR

2007

Tronox filed for bankruptcy

2009

Bankruptcy court approved a settlement agreement with the U.S.
government, 24 state governments, Tronox, and others that established
several trusts, including the Multistate Trust

2011

EPA issued the third FYR

2012

The Multistate Trust installed 13 additional monitoring wells on-site as
part of the Phase I SRI

2015

The Multistate Trust consolidated and disposed off-site (or recycled)
more than 2 million pounds of residual waste

2015-2016

B-l

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Event

Date

The Multistate Trust installed additional on-site and off-site monitoring
wells during the Phase II SRI

2016-2017

EPA issued the fourth FYR

2017

The Multistate Trust implemented the 10-Acre Pond TCRA

2018

The Multistate Trust finalized the SRI

2019

The Multistate Trust finalized the BHHRA and SLERA

2020

The Multistate Trust submitted a draft FFS to EPA and IDEQ

2021

B-2

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APPENDIX C - SITE BACKGROUND - WASTE AND WATER MANAGEMENT

FEATURES

The 2019 SRI Report provided the following description of the waste and water management features
that were contributing contaminants to soil and groundwater.

Solid waste management at the Site historically utilized unlined waste dumps located in the south and
eastern parts of the Site. An engineered, lined landfill was constructed in 1997 in the northern part of the
Site. Water management at the Site evolved over time to accommodate multiple metallurgical upgrades
and multiphase chemical refinement processes and consisted of conveying and storing large volumes of
water. Sixteen surface water ponds, both lined and unlined, were used for settlement, solvent extraction
raffinate, tailings storage, product storage and stormwater retention (Figure D-3 in Appendix D).

West Calcine Repository (Feature 1)

The West Calcine Repository was the first tailings impoundment pond used in the leaching refinement
circuit. Calcine tailings from the operation were impounded west of the plant for the first 10 years of
facility history (1963 to 1973). This area was covered with topsoil and seeded with native grasses in
1973 as a fugitive dust control measure. The calcine tailings were then shifted to bermed ponds on the
eastern side of the Site. This area was not addressed by the ROD because it was believed impacts to the
environment from this area were minimal.

East Calcine Repository (Feature 2)

The East Calcine Repository was a part of the leaching refinement circuit, which functioned as an
unlined active tailings repository from 1973 to 1999. This area was one of three waste areas recognized
by the ROD as a primary source of COCs to groundwater and was a target for remedial design/remedial
action activity. Remedial activities involved partial removal of calcine tailings for resource recovery
operations (1999 to 2000) and placement of an engineered cap (geotextile) over the repository (2001) for
containment. Subsoil and topsoil from the agricultural cropland area on the north side of the Site
(Feature 17) was used in construction of the East Calcine Repository cap. An infiltration gallery was
constructed in 2002 on the north side of the area to capture precipitation runoff from the cap. Another
infiltration gallery was completed in 2004 on the south side of the cap after periodic standing water was
observed at the southwestern corner of the East Calcine Repository near the former Scrubber Pond
(Feature 3). A snow fence was erected along the south side of the facility after snowdrifts on the cap and
increased percolation through the cap were observed.

West Waste Repository (Feature 11)

The selected remedy for groundwater in the 1995 ROD included elimination of solid COC-generating
waste sources, including excavation of solids from the S-X Pond (Feature 7) and Scrubber Pond (Feature
3) into an on-Site repository - the West Waste Repository. During November 1996, S-X Pond sediments
and some underlying soils were scraped to the south end of the pond, covered with plastic and allowed
to dry, and consolidated in place. Scrubber Pond solids were worked into windrows and piles to
accelerate drying. Roughly 13,000 cubic yards of material was removed from the S-X and Scrubber
Pond. A landfill was constructed in 1997 in accordance with Resource Conservation and Recovery Act
Subtitle D requirements for earth construction, primary and secondary liner requirements, leachate
collection and cover design. Repository construction and dig/haul activities took place between July 28
and October 10, 1997. Installation of a geosynthetic clay liner, flexible membrane liner, geocomposite
and native soil protective layer, sump, and ramp occurred between August 16 and August 29, 1997.
Placement of the cover cap occurred between September and October 1997.

C-l

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South Industrial Landfill Area (Feature 12)

The South Industrial Landfill was used from 1967 through 1973. Solid wastes were placed in the
landfill, including wood, paper, office trash and cleaned process equipment. The South Industrial
Landfill was closed in 1973, and trash and other refuse were thereafter disposed in the local landfill. The
south industrial landfill area was also used as a staging area and decontamination pad during
construction of the West Waste Repository in 1997.

North Industrial Landfill (Feature 13)

The North Industrial Landfill, located north of the 10-Acre Pond, was used for disposal of construction
debris associated with the dismantling of the Vanadium Plant, which ceased operations in 1997.
Information documenting the landfill contents has not been found; however, the North Industrial
Landfill represented a source of exposed materials likely containing COCs in solid form. Much of the
material was buried and residual chemicals in soil are likely present in and beneath the landfill contents.

Scrubber Pond (Feature 3)

The Scrubber Pond was a part of the conversion circuit, receiving excess water residuals and particulates
from emission control scrubbers designed to remove dust and particulate matter from the roaster stack.
The unlined pond operated from 1975 to 1997. At maximum throughput, the pond received roughly 210
gallons per minute and transported an estimated 300 tons per year of scrubber residuals. The Scrubber
Pond was taken out of service in 1997 and reclaimed in 1998 by excavation and encapsulation of
primary waste material in the engineered West Waste Repository (Feature 11) and backfilled with native
sediments. The Scrubber Pond was one of three primary sources of COCs to groundwater at the Site, as
recognized in the 1995 ROD.

Boiler Slowdown Pond (Feature 4)

Roaster scrubber solids were impounded in the Boiler Blowdown Pond for the first 10 years of
operation. The Boiler Blowdown Pond served as an unlined retention basin for the mineralized water
derived from water softening activities when the new Scrubber Pond was constructed in 1973. The
Boiler Blowdown Pond was abandoned in 1992, covered with native soils and seeded with native
grasses. The Boiler Blowdown Pond was listed as a possible source area for primary sources (water/soil)
because sediments were left in place during pond closure activities and these sediments were potential
sources to groundwater.

Magnesium Ammonia Phosphate Ponds (Feature 5)

The Magnesium Ammonia Phosphate (MAP) Ponds were a series of three unlined product-holding
ponds that operated as a part of the packaging circuit from 1963 to 1993. MAP is a fertilizer and was the
first by-product refined during the purification step. MAP was flushed to the ponds at an average rate of
5 gallons per minute. Manufacturing practices changed in 1993 in ways that rendered the MAP Ponds
redundant. The ponds were subsequently abandoned by excavating the remaining MAP, selling the
MAP as fertilizer and reclaiming the pond to grade with a native soil cap.

Limestone Settling and Stormwater Ponds (Feature 6)

The Limestone Settling and Stormwater Ponds were a series of five ponds constructed as part of the S-X
circuit that underwent the most changes over time. These ponds were managed in sequence on the
upstream end of the S-X Pond for limestone settlement. The three original ponds were unlined, ranged in
size from 500,000 gallons to 1,000,000 gallons and operated from 1973 to 1989.

Two uncontrolled waste releases were recorded due to integrity failures from these ponds:

C-2

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• September 1989: 650,000 gallons of S-X raffinate was lost to the vadose zone.

• November 1989: 100,000 gallons of S-X raffinate was lost to the vadose zone.

In response to these containment failures, a fourth settling pond lined with a high-density polyethylene
liner was constructed with a capacity of 750,000 gallons. A fifth lined pond was constructed in 1993
with a capacity of 750,000 gallons and was used for settlement and stormwater retention. The fourth and
fifth ponds were installed on top of the original pond locations and remained in use until plant closure in
1998. These two ponds were reclaimed in 2003 by excavating and removing the liners and placing waste
in the 10-Acre Pond. Underlying native soil within the vadose zone was not removed and represented a
potential secondary source of groundwater contamination.

S-X Pond (Feature 7)

The S-X Pond was an unlined 4.5-million-gallon impoundment that operated from 1963 to 1997 as part
of the S-X circuit of the refinement step. The S-X Pond recorded the largest uncontrolled waste release
because of containment failure in April 1983, where 2.5 million gallons of S-X raffinate was lost to the
vadose zone. The pond was reconstructed and enlarged in response to this release from its 4.2-million
gallon capacity to accommodate 5.5 million gallons of raffinate solution. Operation of the S-X Pond
ended in 1995 and was reclaimed in 1997 by excavating sediments, which were relocated to the West
Waste Repository (Feature 11). The S-X Pond was one of three primary sources of COCs to
groundwater recognized in the 1995 ROD.

10-Acre Pond (Feature 8)

The 10-Acre Pond was constructed with a double liner in 1997 with a sump on the south end for leak
detection between the primary and secondary liners. The pond was used as a replacement for the S-X
Pond and to contain liquids and solids from vanadium processing. The pond served as a repository for
the waste from the Limestone Settling and Stormwater Ponds in 2003, and for the waste removed from
the East and West 5-Acre Ponds in 2004. Uncertainty regarding the integrity of the liner beneath the 10-
Acre Pond resulted in the pond being considered as a potential source of groundwater and contaminant
recharge to the aquifer, and was identified as a potential source of COCs to groundwater during the third
FYR.

East and West 5-Acre Ponds (Features 9 and 10, respectively)

The double-lined East and West 5-Acre Ponds were constructed in 1996 in conjunction with the 10-Acre
Pond as a replacement for the S-X Pond, and as part of eliminating uncontrolled liquid discharges
required in the 1995 ROD. These ponds were constructed by recompacting native silty clay soils
overlain with two high-density polyethylene liners separated by a geonet layer. The East and West 5-
Acre Ponds were used to store wastewaters from the vanadium process. The two ponds were closed in
2004 by relocating the water and sediments to the 10-Acre Pond. The liners were rolled, moved to the
northeast corner of the West 5-Acre Pond basin, compacted, covered with reinforced plastic and
weighted down with sandbags.

C-3

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APPENDIX D - SITE MAPS

KERR-MCGEE CHEMICAL CORP.

SODA SPRINGS PLAMT SUPERFUND SITE

	SOOA SPRINGS, IDAHO	

Figure 3-5

STUDY AREA CORE HOLES
AND EXPLORATORY DRILLING
LOCATIONS

^O.J'CT IVfti- e- I REVISIONS
3*TE OCT2Q19 CHbCWa* AK ~|	

HALEY & ALDRICH

Figure D-l: Geologic Faults4

Sb*

/

.,/ 1

i 2l '	;

EXPLANATION

** Type 1 - Coie Hote Willi CMT Multilevel Well
Typo 2 - Core Hole with CMT Multilevel Wall
• Type 3 - Source Area Core Hole

Historical Groundwater, Seep, or Spring Sampling Location

Geologic Fault, U = Up Thrown. D = Down Thrown (Haley & Aldiich, 2018)

	Geologic Fault 
-------
Figure D-2: TCRA Removal Boundaries and Volumes5

TCRA Removal Areas and Volume Summary Table

Calculated Rem oval
Volume In Cubic
Yard*

EXPLANATION

2018 SRi Owe Holei

Type 1 - Cot? rJfi vMrii CMTM..ltllft.=l VVeli
-V T>pe? Cnm • wewrhCMTfeUWeyeiwell
~ r>pc 3 - Soiree Area Core hole
Phasj i/ll SRI Son Sbfings

Phase i S3H nr.ri'o
® Phase soil Uanng

~ Fee. jed Fessibiity Study W6II
CM t Multilevel VVBl1 1 rarreect
ITMicvat'Jin Crv-sa=

_| tj 53LA
Fl B'

NOTES

1 Aerial Imagery source: Es"

3 G) Nil

H) in-AP

n So.fh SrrapA/ea

|	 /.] Stockpile Area

Figure 4-1

TCRA REMOVAL BOUNDARIES
SHOWING REMOVAL VOLUMES
BY AREA

5Source: 2021 TCRA Effectiveness Evaluation

D-2

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Figure D-3: Site Features and Historic Source Areas of Concern6

SITE FEATURE

NAME

1 Wi::a (Rixilurirxl)

2

East! Calotte Repuiiiluiy

3

3i;i u::tiw Puntl (f3«;l;irriKd)

4

Bciikft Bk:»,'jii.vvn Pmxl {Rccluirncfli}

5

fuViP Puiid:; (Rrx:fcjrnixJj

S

limestone SotHinrj and SSomT/itjIrir Pcxiris fRnr.lairrod)

7

S-X Pern (Reclamed)

8

tO-.Ac ns Pond ^^ctamed)

&

Ea&1 G-Acre Pone (Reclamed)

10

Wc« 5-Ajttc nord (Reclaimed*

11

Wok Waste Repository

12

South Industrial Landfll Area (Reclaimed)

13

North Industrial LwicKil (Reclaimed)

11

Vanadium Plant Qismanifed)

lb

i-eniizerpiera i^iamanceai

16

Water Suppy Well (Abandoned)

17

Ciopltrid (Soil C. p Buiru/i Ai«u)

13

RaJ Spur Aiai

IS

Fiy IIK't Calcine £ I id Roaster Reject fiieu (Recldiried)

20

Lii liesluue SloiAplK1 (Rpinuwitl)

21

FartiphtisplouK OieCI(*!*_;e Ai«a (Rtii/kjiiritKS)

22

ChwrifcsalSlniai^s EtiikliiT|.Ciik;iiii! De:t\ul-< n

HALEY & ALDRICH

Source: 2019 SRI Report

D-3

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APPENDIX E - PRESS NOTICE

&EPA

United States
Environmental Protection
Agsney

Cleanup Review Starting for
Kerr-McGee Chemical Corporation
(Soda Springs, ID)

Public Input Welcome

Fifth Five-Year Review: The U.S. Environmental Protection Agency (EPA) is conducting
its fifth regular Five-Year Review of the remedy for the Kerr-McGee Chemical
Corporation (Soda Springs Plant} Superfund Site in Soda Springs, Idaho. Five-Year
Reviews help to ensure ihe selected cleanup actions protect human health and the
environment effectively.

The approximately 547-acre Site is in a rural area about 1-5 miles north of Soda
Springs, Idaho. It is surrounded by agricultural land to the south, east, and north, and
by the P4 Production Plant to the west. From 19G3 to 1999, operators of a vanadium
production plant generated liquid industrial wastes and stored them, on site in ponds,
The unlined ponds leaked chemicals into the groundwater beneath the Site. Work and
waste disposal practices at the Site caused contamination in the groundwater and
surface water. EPA selected a long-term cleanup remedy in the Site's 1995 Record of
Decision (updated in 2000), Cleanup efforts included placement of contaminated
sediment from the three unlined waste ponds in a landfill on site, capping of calcine
tailings, natural attenuation of groundwater contaminants, groundwater monitoring,
and institutional controls (such as deed restrictions or signage),

Remedy construction took place trorn 1997 to 2001 and groundwater monitoring is
ongoing. Additional remedial actions are being evaluated as par) of a Focused
Feasibility Study. The Greenfield Environmental Multistate Trust, LLC leads site
investigation and cleanup activities. EPA provides oversight, in consultation with the
Idaho Department of Environmental Quality,

Do you have information on how the remedy is working? If so, EPA wants to hear
from you by February 28, 2022. EPA invites community participation in the Five-Year
Review process to evaluate cleanup efforts and to ensure it remains protective of
human health and the environment. Community members who have questions about
the Site or who would like to participate in a community interview, are asked to please
contact the following EPA remedial project managers (RPMs):

•	Conor Neal at (206) 553-0603 or n g a I. con or jg) ep a. go v

•	Zoe Lipowski at (206) 553-0526 or iipowski.zoe@epa.gov

For More Information: Visit the Site's local document repository, Soda Springs Public
Library, located at 149 South Main Street in Soda Springs, Idaho 83276, or visit EPA's
website at www.epa.KOv/superfund/kerr mcgee-soda-sprines,

December 16, 2021 in Caribou County Sun

E-l

-------
Cleanup Review Starting for
Kerr-McGee Chemical Corporation
(Soda Springs, ID)

Ertnfonfmfltal Prdettvon

Public Input Welcome

*>EPA

Fifth Five-Year Review: The U S Environmental Protection
Agency {EPA) is conducting its fifth regular Five-Year Review of
the remedy for the Keu-McGee Chemical Corporation (Soda
Springs Piani) Superfund Site in Soda Springs, Idaho. Five-Year
Reviews help to ensure the selected cleanup actions protect
human health and the? environment effectively
The approximately 547-octe Site is in a rural area about
1.5 miles north of Sodo Springs, kJaho It Is surrounded by
agricultural land to the south, east, and north, and by the
P4 Production Plant to Ihe west. From 1963 to 1999, operators
of o vanadium production plant generated liquid Industrial
wastes and stored them on site In ponds The untined ponds
leaked chemicals into the groundwater beneath the Site. Work
and waste disposal practices at the Site caused contamination
in the groundwater and surface water. EPA selected a
long-term cleanup remedy in the Site's 1995 Record of Decision
(updated in 2000), Cleanup efforts included placement
of contaminated sediment from the three unlined waste
ponds m a landfill on site, capping of calcine failings, natural
attenuation of groundwater contaminants, groundwater
monitoring, and Institutional controls (such as deed restrictions
or signage).

Remedy construction toot? place from 1997 to 2001 and
groundwater monitoring is ongoing. Additional remedial
actions are bemg evaluated as part of a Focused Feasibility
Study The Greenfield Enviionmental Multistate Trust. LLC
leads site investigation and cleanup activities. EPA provides
oversight, in consultation with Ihe Idaho Department of

Environmental Quality.	

Do you have information on how the remedy is working?

If so, EPA wants to hear from you by February 28, 2022.
EPA invites community participation in the five-Year Review
process to evaluate cleanup efforts and to ensure it remains
protective of human health and the environment Community
members who have questions about the Site or who would
like to participate m a community interview, are asked to
please contact the following EPA remedial project managers
(RPMs):

*	Conor Meal at (206) 553-0603 or neat-conorfe'epa .aov

•	Zoe LipOwsSa at (206) 553-0526 or liQQW.sk! zoe^epa.qov

For More Information; Visit the Site's local document
repository. Soda Springs Public Library, located at
149 South Main Street in Soda Springs. Idaho 83276,
or visit EPA's website at

www.ep a .go v /superfund /kerr-mcqee-soda-sp rings,

December 19, 2021 in Idaho State Journal

E-2

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APPENDIX F - INTERVIEW FORMS

KERR-MCGEE (SODA SPRINGS, ID) SUPERFUND SITE
FIVE-YEAR REVIEW INTERVIEW FORM

Site Name: Kerr-McGee (Soda Springs, ID) Superfund Site

EPA ID: IDD041310707

Interviewer name:

Interviewer affiliation:

Subject name: Lars Peterson

Subject affiliation: Multistate Trust

Subject contact information: LP@g-etg.com. 480-319-3638

Interview date: 2/28/2022

Interview time:

Interview location:

Interview format (circle one): In Person Phone Mail Email Other:

Interview category: Multistate Trust

1. What is your overall impression of the remedial activities at the Site?

Initial remedial activities selected in the 1995 Record of Decision (ROD) and implemented
by 1997 were followed by a sustained period of approximately ten years of consistent and
substantial declines in Site-related contamination. By about 2007, the rate of improvement of
Site conditions began to slow in some areas, and it was determined that additional evaluation
of the cause for the slowed improvement was warranted. In 2009, however, the owner of the
Site at that time, Tronox Incorporated (Tronox), filed for bankruptcy; therefore additional
investigation and cleanup actions around the time of the Tronox bankruptcy were limited.

Under a bankruptcy settlement approved by the U.S. Bankruptcy Court for the Southern
District of New York and effective as of February 11, 2011, Tronox resolved its
environmental liabilities with the EPA, and ownership of the Site, as well as limited funding
to maintain it, was transferred to the Multistate Environmental Response Trust (Multistate
Trust). The majority of funding to perform additional remedial activities at the Site after the
bankruptcy was not available until 2015 and 2016 when litigation against another party,
Anadarko, resulted in additional funding for remediation.

With the support, leadership, and under the oversight of the U.S. Environmental Protection
Agency (EPA) and the Idaho Department of Environmental Quality (IDEQ), since the receipt
of Anadarko funds in 2015 and 2016, the Multistate Trust has completed a significant
amount of site investigation and remedial action activities on parallel paths. The following
site investigations and studies have been designed and implemented to fully characterize the
nature and extent of contamination and to support EPA issuance of a ROD Amendment:
• Supplemental Remedial Investigations (SRIs, 2015 - 2020) have covered extensive
on- and off-Site sampling and fieldwork, including installation of 76 groundwater
monitoring wells (using innovative, continuous multichannel tubing wells installed in
"transects"), drilling over 10,000 feet of soil borings, and collecting 1,167
groundwater, surface water, soil, and other samples, and updating the conceptual site
model;

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•	An LPA-approved Baseline ilunian Health Risk Assessment was completed (20 17
2020). encompassing preparation of a Conceptual Site Model and Exposure Scenarios
and Assumplions Report, and Pathway Analysis Report:

•	An HPA-approved Screening Level Keologioal Risk Assessment was completed
(2017 2020). encompassing a habitat survey and Problem Formulation Report:

» Ongoing Focused Feasibility Study (ITS) activities have been completed to evaluate
options for modifying improving the existing lemedy. which have included
preparation and implementation of a Data Collection Work Plan (2018) for laboratory
testing, bench-scale testing, and field-scale pilot testing lor various redox
manipulation methods to identify options for addressing impacts of subsurface
geochemistry on the mobility and migration of metals: a Monitored Natural
Attenuation (M\A) Evaluation to assess the suitability of NINA in conjunction with
the remedial actions implemented to date by the Multistats Trust. The Draft FFS
Report was .submitted for FI'A review in 2021:

•	An e\alualion of the anticipated effects ofthe 10-Aere Pond Time-Critical Removal
Action (TCRA) was completed (2020 2021) using multiple Site-specific variables
to model forecast future groundwater concentrations to evaluate whether additional
remedial actions, if any. may be warranted and or the circumstances under which
additional active remediation may be warranted in the future: and

» The addition ofthe City of Soda Springs (City) water supply to the ongoing long-term
monitoring (LTM) program to confirm that the City water supply is not impacted by
Site contamination.

Concurrent with the above-described activities, the Muilistatc Trust has also performed
extensive remedial actions to reduce risk to human health and the environment, and
proaetively lake actions to improve environmental conditions, including:

•	Building Demolition and Donation 1.7 dilapidated buildings w ere demolished and 1
building was dismantled and donated to the City to improve delineation of
contamination and support ongoing groundwater monitoring operations, support more
comprehensive source removal, and improve the value ol'lhe Site because ofthe
extremely deteriorated condition of most ofthe buildings:

» The 10-Acre Pond TCRA. which entailed removal and disposal of 1.25 million

gallons of highly contaminated liquid that had been stored in an impoundment with a
deteriorating liner. 34.542 cubic yards of pond solids, and 18.302 cubic yards of
underlying soils (completed on an expedited schedule in conjunction w ith the
additional actions described here):

•	Source area removal actions, which included excavation and placement of nearly
400.000 cubic yards of w aste (including the 10-Acre Pond TCRA w aste materials
described above) in a newly constructed on-Site repository : construction of a new on-
Site lined repository (with a leachatc collection system) to house the excavated
materials from the 10-Acre Pond TCRA and the source area removal (which not onh
remov ed calcine source material but also realized cost savings of more than S2.0
million by both utilizing sandy calcine waste as a repository cushion material and
applying 10-acre pond liquids as dust control within the waste repository during
construction): and

F-2

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•	Regrading the Silo to direct surface water runoff away from residual source areas
(located at depths that exceed excavation limits) that, if not redirected, could continue
leaching of residual contamination to groundwater.

2.	What have been the effects of this Site on the surrounding community, if any"'

Whenever possible, Site-related activities are managed in a way lo facilitate positive effects
on the surrounding community. Several examples include:

•	Through focus on local hiring and investing in the community, work conducted at
and or for the Site has produced an estimated 20 temporary local and regional jobs:

•	During the building demolition project in 201X. the Multistate Trust dismantled and
donated a ±4.800 square-foot building to the City for its future use:

•	The Multistate Trust has worked with the City and Caribou County fire departments
to design, construct, and maintain a lire break on-Site to protect the surrounding
community from the risk of spreading wildfire.

•	Weed management is conducted on an on-going basis to prevent the spread of
nuisance weeds from negatively impacting surrounding land, including nearby
agricultural fields.

in addition, one of the goals of the Multistate Trust is to facilitate the beneficial reuse of the
Site. Sexeral examples of work to accomplish this which benefits the community include:

•	Approximately 278 acres of the Site (in an area not impacted by Site-related
contamination) are leased for fanning to a local resident farmer.

•	Three on-Site buildings are leased to a local family for storage use (also in an area not
impacted b> Site-related contamination).

•	The Multistate Trust communicates regularly with the City Council and the l our
Countv Alliance of Southeastern Idaho lo identify and evaluate prospective
companies looking lo site a business, and or to respond to inquiries of businesses
considering the properly for reuse.

With respect to Site-related contamination that has migrated off-Site, the F.PA-approved Risk
Assessment concluded that risk to human health is only present in the in pothetical case of
contaminated groundwater being used for domestic purposes 1 Sowever. all properties located
in the vicinity of the Site-related groundwater contamination are provided clean water for
domestic use by the City, and based on a well survey of the area, no domestic wells are
believed to exist in the area of contaminated groundwater. In addition, the Multistate Trust
samples the City water supply on an annual basis to ensure Site-related contamination is not
present in City water

3.	What is your assessment of the current perlormance of the remedy in place at the Site''

As noted in response to Question 1 above, the original remedy resulted in a sustained period
of approximately ten years of consistent and substantial declines in Site-related
contamination. While those declines have diminished in certain areas, other areas continue to
exhibit these decreasing trends, for example. Big Spring, located south of the Site has
exhibited a steady decreasing molybdenum concentration that has reduced from 500

F-3

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micrograms per liter (ug l .) in 1997 to approximately 100 ug 1. in 2021, w hich is equal to the
F P.\ threshold for sale tap water.

Removal ol the 10-Acre Pond as a Time-Critical Removal Action in 2018. along w ith the
waste excavation, building demolition, and Site regrading that was performed in conjunction
with the 10-Acre Pond TCRA resulted in a significant amount of Site cleanup being
accomplished under a compressed schedule (in parallel w ith the preparation of the ITS
Report and the track to complete a ROD Amendment). These activities resulted in the
cleanup of 1.25 million gallons of highly contaminated liquid and placement of nearly
400.000 cubic yards of contaminated soils and pond solids in a newly constructed on-Site
repository. Groundwater modeling conducted since that lime has demonstrated that the 10-
Acre Pond TCRA and associated remedial actions have accelerated the time to cleanup by up
to 50 years in some areas of the Site. As such, the completion of these activities since the last
Five-Year Review represents a very notable improvement in the remedy and the Site
conditions.

Finally, the Draft FFS Report was prepared in 2021 to evaluate what additional remedial
actions are appropriate for the Site, and the Final IT'S Report is anticipated to be approved by

EPA in 2022.

4, Are you aw are of any complaints or inquiries regarding reuse of the Site, environmental
issues, or the remedial action from residents since implementation of the cleanup?

The Mullistale Trust works closely w ith the local government and community stakeholders
by meeting frequently w ith representatives from the City to provide updates on Site
activities; hosting Site lours and eohosting an open house event with FT'A and IDF.Q:
participating in various community events: and meeting with Bayer (formerly Monsanto),
which operates a manufacturing plant in close proximity to the Site. During recent meetings
w ith the City Council, the Viultistate Trust has discussed opportunities for Site re-use
identified by council members, and the Multistate Trust has followed up on these
opportunities as appropriate. In approximately 2016 and 201 7, the Mayor of the City at the
time. Mayor Jim Smith, expressed his view that the Site should be host to a major industrial
employer, such as a company that would supply full-time employment to dozens of local
residents Former Mayor Smith and some City Council members have also voiced their
frustration regarding the length of time needed for Site cleanup, and disappointment that the
Site cleanup is not yet complete.

Inquiries related to such environmental issues have included:

•	In 201 8, an adjacent landowner expressed a concern thai windblown dust had moved
Site contamination onto his agricultural field. The Multistate Trust worked directly
with the landowner, and implemented a comprehensive soil sampling program to
evaluate the concern. No Site-related contamination was found on the adjacent
property.

*	In March 2020, a local properly owner reported to TDF.Q (hat their domestic well

w ater had a bad taste or change of laste. and inquired w hether this could have been
caused by Site-related contamination entering the resident's well. 'ITie Multistate

F-4

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Trust w orked with IDEQ to compile relevant information, including historical sample
results from the subject well and other nearby wells and the groundwater How
direction in the area. IDEQ communicated to the property owner that they did not
believe Site-related contamination would have migrated to their property or well and
advised the property owner that they could sample their well w ater to confirm. The
owner collected a sample and I hen reported to IDEQ in May 2020 that the
concentrations were all low and had actually decreased since the last time the well
was sampled. No further action w as necessary.

5.	Are you getting information from the EPA and IDEQ during the Super fund cleanup process'1

Yes. The Multistate Trust works very closely w ith EPA and IDEQ for all matters related to
the Site, holding regular meetings typically at least monthly, and often more freijuenlly.
Meetings with EPA and 1 DEC) also regularly include communitv stakeholders, such as the
City Council (typically 1-2 meetings per year), and public meetings or open houses. The
Multistate Trust also works w ith EPA and IDEQ to help ensure information related to the
Superfund cleanup process is being made av ailable to the community, for example:

•	fact sheets are regularly prepared and distributed. Most recently, a Site Overview fact
sheet was jointly prepared in January 2022 by the EPA. IDEQ, and Multistate Trust.
A mailing list was procured, and fact sheets were mailed out to more than 2.400
residents and businesses in the Soda Springs area.

•	The Multistate Trust website for ihe Site is being finalized and is expected to go live
in March 2022 (htlns: sodaspnn^.iu'ccnlieldenvironmcnlai.cons'). The website will
include general information, materials, and links to resources in order to give the
public easy access to information about the Site and to improve community
awareness of the Site and our investigations, remediation, and reuse planning.

•	The Community Involvement Plan is being updated in earl}' 2022 alter public
interviews are completed in the spring.

6.	Are you comfortable w ith the status of the institutional controls at the Site\> 1 knot, what are
the associated outstanding issues?

On-Sile and off-Site institutional controls for the Site are discussed separately below:

A form of on-Site institutional control is m place due to the fact that the property is owned by
the Multistate Trust, and no sale or lease of the property is permitted without approval by the
beneficiaries of the Multistate Trust, including the f'nited States (with EPA acting lead
agency) and the State of Idaho (with IDEQ acting as non-lead agency). A traditional
institutional control in the form of a deed notice is anticipated after the forthcoming ROD
Amendment is completed. The deed notice for on-Site land use restrictions is anticipated to
include: (1) restriction to commercial industrial land uses, and (2) groundwater use
restrictions in accordance with commercial industrial use of groundwater. The EPA-approved
Human Health Risk Assessment and the Draft EES Report both propose Preliminary
Groundwater Cleanup Eevels. l or the on-Site commercial industrial worker, vanadium at
lev els above 930 ug E is the only contaminant of concern (COC ) that would present an

F-5

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unacceptable risk to human health (presuming commercial industrial exposure). Based on
this information, the institutional control anticipated for on-Site groundwater use restriction
is to prevent commercial 'industrial use of groundwater exhibiting vanadium at levels above
930 iig I,. However, formal establishment of this institutional control is not expected to be
completed until after the ROD Amendment is finalized, because the final appro\ed industrial
cleanup level established in the ROD Amendment may not exactly match the cleanup level
currently proposed. In the meantime, the institutional control that already exists through
ownership of the Site in a trust, with properly sale and re-usc mailers subject to f.PA and
IDKQ approval, should remain protective.

With regard io off-Site institutional controls, based on ongoing discussions with KPA. IDKQ
and the Idaho Department of Waler Resources (IDWR). the Multistate Trust is in the process
of preparing a Petition for Area of Drilling Concern (ADC) lo prohibit the installation of
drinking water wells in the area of off-Site groundwater contamination. The petition will be
submitted to IDWR for its review and consideration. Establishment of the ADC would In-
dependent on several factors, including IDWR evaluation of the petition and public feedback
should IDWR choose to present the ADC for public consideration. Based on meetings with
KPA and 1DKQ. the ADC appears to be the best form of oil-Site institutional control
a\ailable lor use. It should also be noted lhat a domestic well survey has been completed, and
based on review of publicly available information and alter community outreach including
direct mailings and door-to-door knocking, no private wells have been identified within the
area of Site-related groundwater contamination (excluding monitoring wells), furthermore,
the Multistate Trust has also confirmed through communications with the City thai clean
water provided by the City to its resident and lo select locations outside of city limits is
available lo all properties lhat are located geographically within the area of Site-related
groundwater contamination. As such, if a previously unidentified private drinking water well
would be discovered wilhin the area of Site-related groundwater contamination,
abandonment of the w ell and use of clean city w ater as an alternative w ould likely be a
reasonable option lo eliminate the risk of potential domestic use of contaminated
groundwater.

7. Do y ou have any comments, suggestions or recommendations regarding the management or
operation of the Site's remedy ?

The Multistate Trust would like to aeknow ledge the support and leadership pro\ ided by KPA
and IDKQ in the planning, approval, and implementation of the 10-Aere Pond TCRA and
associated waste excavation, building demolition, repository construction, and Site regrading.
These considerable endeavors were undertaken concurrently with the ongoing SRI and FFS
process. By approving work to respond to the potential risks posed by the 10-Aere Pond in a
time-critical fashion, a very significant amount of Site cleanup was achieved in a short period
of lime. As noted above, the 10-Acre Pond TCRA reduced cleanup time by as much as 50
years in some areas of the Site. While the SRI was appro\ed in 2020. the FFS Report is
expected to be approved in 2022. and the ROD Amendment will be completed soon
thereafter, it is acknowledged thai the linear process of Superfund cleanup does typically take
many years. In this case, the Superfund process for the Site is slill advancing, while at the
same lime the decision to address certain Site risks in 2018 in a time-critical manner was a

F-6

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remarkable success story in making very rapid progress tow ards cleaning up a Superlund
sile.

8, Do you consent lo have your name included along with your responses lo this questionnaire
in the FYR report?

Yes.

F-7

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KERR-MCGEE (SODA SPRINGS, ID) SUPERFUND SITE
FIVE-YEAR REVIEW INTERVIEW FORM

Site Name: Kcrr-McGcc (Soda Springs, ID) Supcrfuml Site

EPA ID: IDD041310707







Interviewer name:



1 n t e r'v i ewe r a H1 li a (i 0 n:



—< /

Subject name: 3 Cp"ff L 1 "i 1



Subject affiliation:



J , J

Subject contact information:







Interview date:



Interview time:



Interview location:







Interview format (circle one): In Person

Phone Mail Email

Other:

Interview category: O&M Contractor







1.	What is your overall impression of the project, including cleanup, maintenance and reuse
activities (as appropriate)?

2.	What is your assessment of the current performance of the remedy in place at the Site?

3.	What are the findings from the monitoring data? What are the key trends in contaminant
levels that are being documented over time at the Site?

4.	Is there a continuous on-site O&M presence? If so, please describe staff responsibilities and
activities. Alternatively, please describe staff responsibilities and the frequency of site
inspections and activities if there is not a continuous on-site O&M presence.

5.	Have there been any significant changes in site O&M requirements, maintenance schedules
or sampling routines since start-up or in the last five years? If so, do they affect the
protect!veness or effectiveness of the remedy? Please describe changes and impacts,

6.	Have there been unexpected O&M difficulties or costs at the Site since start-up or in the last
five years? If so, please provide details.

7.	Have there been opportunities to optimize O&M activities or sampling efforts? Please
describe changes and any resulting or desired cost savings or improved efficiencies.

8.	Do you have any comments, suggestions or recommendations regarding O&M activities and
schedules at the Site?

9.	Is there anything specific about the Site that you hear about often, especially from any
community members you may encounter? Are there worries, concerns, fears or questions
about the contents of the Site?

10.	Do you consent to have your name included along with your responses to this questionnaire
in the FYR report?

F-8

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1 - There has been a lot accomplished towards the cleanup of this site in my opinion. The work has
been done right and in a timely manner. Many upgrades have been implemented.

2 - The path towards a remedy seems straight, many steps in the right direction.

3	-1 am not involved in monitoring site data and have no input on this question.

4	- There is currently no continuous on-site O&M presence. The site is inspected several times a week
to make sure the site remains secure and that there are no obvious issues. The site is thoroughly
inspected once per month for erosion, weeds, leachate level measurements and leachate pumping
when needed.

5 - Yes, most of the buildings were demolished at the site eliminating fire hazards and ongoing
maintenance of the structures.

6-No

7 - None at this time.

8 - This site is being well taken care, monthly audits, weekly checks, site maintenance when needed,
fence repairs when needed and spraying.

9 - Nothing on worries or fears from the community, more good comments on how people are
impressed with site cleanup actions.

10 - Yes

F-9

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KERR-MCGEE (SODA SPRINGS, ID) SUPERFUND SITE
FIVE-YEAR REVIEW INTERVIEW FORM

Site Name: Kerr-McGee (Soda Springs, ID) Superfund Site

EPA ID: IDD041310707

Interviewer name: Johnny Zimmerman-Ward

Interviewer affiliation: Skeo

Subject name: Joel L Gerhart, P.E.

Subject affiliation: Gerhart Engineering,
LLC

Interview date: February 24, 2022

Interview time: 11:00 AM MST

Interview location: Subject completed interview form as an individual

Interview format (circle one): In Person

Phone

Mail

Email

Other:

Interview category: O&M Contractor

1.	What is your overall impression of the project, including cleanup, maintenance and reuse activities
(as appropriate)?

•	Cleanup progress during the last five years has been particularly good. Demolition of the
buildings, removal of the 10-Acre Pond, removal of the west calcine tailings, removal of several
small on-Site landfills, construction of the new on-Site repository, and site regrading reduced
direct contact risks and should benefit groundwater in time. Regular site inspections and general
maintenance of the 2 remaining buildings and facilities have adequately stabilized the site to
support on-going monitoring, maintenance, and investigation activities. Demolition of the other
Site buildings and removal and replacement of the failing gas, electric, and water services to the
Site reduced physical hazards and created a better starting point for potential Site redevelopment
activities.

2.	What is your assessment of the current performance of the remedy in place at the Site?

•	Source elimination activities completed in the 1990s resulted in significantly lower COC
concentrations in on- and off-Site groundwater. However, groundwater still exceeds applicable
standards or certain risk exposure scenarios both on- and off-Site. Ongoing contributions from
primary on-Site source materials such as the west calcine tailings (recently removed during the
10-Acre Pond Time Critical Removal Action [TCRA]) and from secondary source materials in
the vadose and saturated zones related to historical site operations (not accessible for removal)
appear to be contributing to the ongoing exceedances. Removal of the west calcine primary
source material and site regrading should reduce the ongoing contributions, but more monitoring
is needed to assess the degree of reduction achieved.

3.	What are the findings from the monitoring data? What are the key trends in contaminant levels that
are being documented over time at the Site?

•	Long-term trends show large reductions in concentrations throughout most of the Site and at
most off-Site locations related to the liquid source elimination. More monitoring data are needed
after the TCRA activities to prove and assess any changes in long-term trends.

4.	Is there a continuous on-site O&M presence? If so, please describe staff responsibilities and
activities. Alternatively, please describe staff responsibilities and the frequency of site inspections
and activities if there is not a continuous on-site O&M presence.

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•	I am not adequately familiar with the exact schedule for on-Site O&M activities to provide an
answer.

5.	Have there been any significant changes in site O&M requirements, maintenance schedules or
sampling routines since start-up or in the last five years? If so, do they affect the protectiveness or
effectiveness of the remedy? Please describe changes and impacts.

•	The O&M plan has been updated and approved by EPA (Environmental Protection Agency) and
IDEQ (Idaho Department of Environmental Quality). The high-resolution monitor well network
implemented through the Supplemental Remedial Investigation (SRI) activities combined with
expansion of the sampling parameters and twice annual sampling is an excellent means to detect
changes in the plumes that may affect potential receptors.

6.	Have there been unexpected O&M difficulties or costs at the Site since start-up or in the last five
years? If so, please provide details.

•	The Site buildings and utilities were in a severely dilapidated condition prior to Site Demolition
making the Site inspection and maintenance activities difficult and dangerous. Removal of the
buildings, decommissioning of the failing utilities, and replacing utilities significantly improved
the safety and operability of the Site. Site access is still challenging during winter months.

7.	Have there been opportunities to optimize O&M activities or sampling efforts? Please describe
changes and any resulting or desired cost savings or improved efficiencies.

•	The monitoring plan has been changed several times in the past 5 years. Certain wells and
sampling ports that are no longer needed have been eliminated from the monitoring program.
Parameters have been added as needed to support various analyses associated with the ongoing
Focused Feasibility Study (FFS). The monitoring well network and monitoring program supply a
very complete and robust dataset for these analyses without collecting extraneous or unnecessary
data.

8.	Do you have any comments, suggestions or recommendations regarding O&M activities and
schedules at the Site?

•	At least a few more years of monitoring data are needed to show trends and assess the effects of
the source removal and regrading conducted as part of the 10-Acre Pond TCRA.

9.	Is there anything specific about the Site that you hear about often, especially from any community
members you may encounter? Are there worries, concerns, fears or questions about the contents of
the Site?

•	The community often expresses a desire to see the Site redeveloped to create jobs and increase
economic opportunities. Local officials also express concerns related to fire safety, mowing, and
fire breaks at the Site. Since the facility is no longer in operation and fire concerns are
commensurately reduced, it may be beneficial to minimize mowing to allow native vegetation to
develop to enhance habitat, reduce erosion, and further minimize infiltration at the Site. Several
community members have commented that the Site looks much better after the Site demolition
and west calcine removal activities, and removal of the buildings has eliminated a potentially
dangerous attractive nuisance.

10.	Do you consent to have your name included along with your responses to this questionnaire in the
FYR report?

•	Yes

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KERR-MCGEE (SODA SPRINGS, ID) SUPERFUND SITE



FIVE-YEAR REVIEW INTERVIEW FORM



Site Name: Kerr-McGee (Soda Springs, ID) Superfund Site

EPA ID: IDD041310707

Interviewer name:

Interviewer affiliation:

Subject name: Stan Christensen

Subject affiliation: IDEQ

Interview date: February 18, 2022

Interview time:

Interview location: 2:20 pm MST

Interview format (circle one): In Person Phone Mail Email

Other:

Interview category: State Agency

1.	What is your overall impression of the project, including cleanup, maintenance and reuse activities
(as appropriate)?

•	I have a very positive impression of this project. I feel the Trust has installed a very robust
groundwater monitoring system that provides a great synopsis of site conditions and the extent of
the impacted plumes. The Trust has been very aggressive in removing remaining source
materials and in cleaning up the site in general. They removed old dumping areas from the site,
calcine material and the 10 acre pond. They also removed most of the buildings and donated the
structure from one building to the city of Soda Springs.

2.	What is your assessment of the current performance of the remedy in place at the Site?

•	Much has been done to improve conditions at the site. Unfortunately groundwater impacts still
remain. The Trust is working on an FFS report which will detail further remedial actions. The
contaminated plumes have dwindled in size but they still are quite large and impact areas off-site
and within the city of Soda Springs. The current remedy has not been adequate to remove and
contain the contamination over the years it has been in place.

3.	Are you aware of any complaints or inquiries regarding site-related environmental issues or remedial
activities from residents in the past five years?

•	There was inquiry from one resident, who has a private groundwater well on his property that he
had concerns might be impacted from the site contamination. Tests showed no impact. This was
in the spring of 2020. Another property northeast of the site also inquired for soil impacts.
Testing was conducted as part of the SRI report. I believe no impacts were found.

4.	Has your office conducted any site-related activities or communications in the past five years? If so,
please describe the purpose and results of these activities.

•	I handled communication with the resident on his well concerns. I have attended yearly update
meetings with city officials and a public meeting held in 2017.

5.	Are you aware of any changes to state laws that might affect the protectiveness of the Site's remedy?

•	No I am not aware of any state law changes that could affect protectiveness of the site remedy.

6.	Are you comfortable with the status of the institutional controls at the Site? If not, what are the
associated outstanding issues?

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•	I am comfortable with the ICs at the site.

7.	Are you aware of any changes in projected land use(s) at the Site?

•	No I am not aware of any projected land uses at the site.

8.	How would you describe the community's relationship with EPA and the IDEQ during the
Superfund cleanup process?

•	I believe the relationship between the agencies and community is very good.

9.	Do you have any comments, suggestions or recommendations regarding the management or
operation of the Site's remedy?

•	I do not. I believe the TCRA in 2017-2018 did a lot to improve the site conditions. The
monitoring network is excellent and the FFS will hold more details and suggestions to proceed
further with cleaning the groundwater contamination emanating from the site.

10.	Do you consent to have your name included along with your responses to this questionnaire in the
FYR report?

•	Yes.

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KERR-MCGEE (SODA SPRINGS, ID) SUPERFUND SITE
FIVE-YEAR REVIEW INTERVIEW FORM

Site Name: Kerr-McGee (Soda Springs, ID) Superfund Site

EPA ID: IDD041310707

Interviewer name: Meshach Padilla

Interviewer affiliation: EPA

Subject name: Bryce Somsen

Subject affiliation: Caribou County
Commissioner

Interview date: March 25, 2022

Interview time: 8:00PM MT

Interview location: Phone

Interview format (circle one): In Person

Phone

Mail

Email

Other:

Interview category: Local Government

1.	Are you aware of the former environmental issues at the Site and the cleanup activities that have
taken place to date?

•	Yes, ever since it started.

2.	Do you feel well-informed regarding the Site's activities and remedial progress? If not, how might
EPA convey site-related information in the future?

•	Yes, informed enough. Perfect amount.

3.	Have there been any problems with unusual or unexpected activities at the Site, such as emergency
response, vandalism or trespassing?

•	Not that I am aware of.

4.	Are you aware of any changes to state laws or local regulations that might affect the protectiveness
of the Site's remedy?

•	No, I am not.

5.	Are you aware of any changes in projected land use(s) at the Site?

•	No, I am not. County has been trying to promote solar energy by suggesting a solar farm on the
former site. County has reached out to solar companies about creating a solar farm, but no
response from company.

6.	Has EPA kept involved parties and surrounding neighbors informed of activities at the Site?

•	How can EPA best provide site-related information in the future? Yes, through the local
newspaper (Caribou County Sun). It's been a while since EPA has provided updates, maybe
provide some more information.

•	EPA should provide recommendations on how to use the land. Provide information on what
can/cannot be done on the site. Provide way to contact someone through the EPA for more
information.

•	County Commissioner's use social media extensively to share information.

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7.	Has the community been receiving sufficient technical information from EPA? Has this information
been clear and easy-to-understand? If not, describe the areas where you believe the community may
need assistance understanding and responding to information about the Site?

•	I don't know. Probably. Everyone knows about last remedial actions. People only need general
information and images/visuals. Most people understand what's going on.

8.	How would you describe the community's relationship with EPA and your organization during the
Superfund cleanup process? I don't know.

•	Good really. Soda Springs is mining community. When you mention EPA in some places, they
spit on the ground, but there's no problems at all. EPA is done above what was expected. NOTE:
CIC had to inform/remind the interviewee that the current remedial actions were not fully
effective, that's why we're doing CIP interviews. Interviewee was surprised and CIC offered to
re-send the current factsheet and told them that they could email/call CIC for any additional
questions.

9.	Do you have any comments, suggestions or recommendations regarding the project?

•	No. Solar farms would be perfect after the remediation is done. Interested to see if a solar farm
would cause any disturbance to the remediation.

10.	Do you consent to have your name included along with your responses to this questionnaire in the
FYR report?

•	Sure.

11.	Is there anyone else who you would suggest we should talk to?

•	No, not really.

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KERR-MCGEE (SODA SPRINGS, ID) SUPERFUND SITE
FIVE-YEAR REVIEW INTERVIEW FORM

Site Name: Kerr-McGee (Soda Springs, ID) Superfund Site

EPA ID: IDD041310707

Interviewer name: Meshach Padilla

Interviewer affiliation: EPA

Subject name: Eric Hobson

Subject affiliation: Caribou County
Director of Public Safety

Interview date: March 11, 2022

Interview time: 11:00AM EST

Interview location: Phone

Interview format (circle one): In Person

Phone

Mail

Email

Other:

Interview category: Local Government

Mr. Hobson indicated he reviewed the provided fact sheet and read through the information on the
website prior to the call.

1.	Are you aware of the former environmental issues at the Site and the cleanup activities that have
taken place to date?

•	When they started to do the remediation, we met with Greenfield team and they provided
us information and kept us updated on the process.

•	Yes, one of the guys that works for me used to work out there for many years. I have
been familiar with the process with the vanadium extraction. Our community has
multiple Superfund sites, so we are used to and familiar with them through our LAPC
process. We were informed of the cleanup plan and the stages involved, as well as the
overall process. We are periodically updated on the progress, which is helpful and keeps
us informed.

2.	Do you feel well-informed regarding the Site's activities and remedial progress? If not, how
might EPA convey site-related information in the future?

•	Yes. On the county side, they came to talk to us for staging meetings. Because we have
industry in the area, we have a very active LAPC and they report to LAPC. It has worked
out great. They provide very regular updates through a phone call or email updates. We
had large amounts of input both on the city and county sides.

•	I feel like the way information is shared now is the best way to do it. We have heard
about doing it more digitally and on social media, but I don't prefer to share it on social
media due to comments and it sometimes gets disrupted with misinformation. You could
possibly reach more people with social media, but it could run like wildfire and
comments have to be turned off as people argue. We have had public hearings, flyers,
local paper notices, local county and city meetings and that seems to be the best way to
share the direct and targeted information about the Site.

3.	Have there been any problems with unusual or unexpected activities at the Site, such as
emergency response, vandalism or trespassing?

•	None that I know of. Would defer to sheriff for definitive answer. We haven't had to
respond to the Site, and in past had an emergency response plan with Terratech.

F-16

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4.	Are you aware of any changes to state laws or local regulations that might affect the
protectiveness of the Site's remedy?

•	None that I'm aware of, but we don't necessarily follow the IDEQ and EPA regulations.
Locally, we don't have any local rules, ordinances or laws that regulate the industries.
We have a great relationship with the local facilities and they usually go through the
correct permitting processes as needed.

5.	Are you aware of any changes in projected land use(s) at the Site?

•	Not aware of any, but I know the goal is to reuse the Site. There were a lot of little talks
about what to do with the Site. We know they left the landfill onsite and wonder how that
is taken into account during reuse. We heard they had considered a new rail spur on site,
but it didn't end up happening.

6.	Has EPA kept involved parties and surrounding neighbors informed of activities at the Site?
How can EPA best provide site-related information in the future?

•	We were kept informed through fliers and public meetings. I know that they talked about
talking to neighbors of the Site, but not sure if they actually spoke to neighboring
residents/farms.

•	Best way to provide site-related information is through the weekly local paper and
presenting at a local, public meeting (city council or county commission).

•	Meshach: how would the community respond to a virtual meeting option?

Likely more receptive to a virtual meeting since we all know what zoom is now
and have worked remotely for two years. I think you get more people coming to a
public meeting in person, and is the best method, but anyone that works in any
form of business would be comfortable with virtual.

•	Meshach: what is internet availability in the area?

It is a bit hit or miss. We have two local options in town, and outside of town we
have some other options. Most folks have internet access, even if it's a hotspot on
their phone.

7.	Has the community been receiving sufficient technical information from EPA? Has this
information been clear and easy-to-understand? If not, describe the areas where you believe the
community may need assistance understanding and responding to information about the Site?

•	I think it has been great information. It's not the most technical information but it's
geared to the people reading it. I like that every time a flyer goes out or we go to a
meeting, in comes the poster board with maps and figures, which is helpful. The visuals
help the community to understand what is going on at the Site. The fact sheet was very
informative and explained what was going on at the Site.

8.	How would you describe the community's relationship with EPA and your organization during
the Superfund cleanup process?

•	Pretty good, we have multiple sites here, and most of the population works at one of the
facilities. Most people are used to them here. Locally I don't think we have problems
with communication with EPA. There are a few folks who do not care for the government
and may not understand roles of the involved entities. Once the purpose is explained
and/or clarified, people will understand since they are familiar with the remediation
happening at the sites.

9.	Do you have any comments, suggestions or recommendations regarding the project?

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•	One thing I thought that was weird about the proj ect (please note I'm not a site manager,
engineer, chemist, etc.) is how they left the landfill on the Site. If you leave the landfill,
does it make it harder to reuse the Site? You would think you would want that gone.

10.	Do you consent to have your name included along with your responses to this questionnaire in
the FYR report?

•	Yes.

11.	Is there anyone else we should talk to?

•	From the city: Mitch Hart and city manager

F-18

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KERR-MCGEE (SODA SPRINGS, ID) SUPERFUND SITE
FIVE-YEAR REVIEW INTERVIEW FORM
Site Name: Kerr-McGee (Soda Springs, ID) Superfund Site

EPA ID: IDD041310707

Interviewer name: Meshach Padilla, with
support by Laura Knudsen

Subject name: Mitch Hart

Interview date: March 8, 2022
Interview location: Phone

Interviewer affiliation: EPA

Subject affiliation: Soda Springs City
Council President

Interview time: 1:30PM EST

Interview format (circle one): In Person Phone Mail Email Other:
Written response also provided by email on February 25, 2022.

Interview category: Local Government

Refer to February 25, 2022 written response for additional information.

1.	Are you aware of the former environmental issues at the Site and the cleanup activities that have
taken place to date?

•	Yes - see written response.

2.	Do you feel well-informed regarding the Site's activities and remedial progress? If not, how
might EPA convey site-related information in the future?

•	Yes, I am well informed. As a city leader, I have more latitude and have received more
information than a regular citizen. Until the Trust took over, there was sporadic information
shared; information is now more readily available. They have generously responded to
requests and provided tours of the Site. The previous Mayor raised concerns about risk of fire
with grass and weed control and the Trust was very responsive. The latest fact sheet was
helpful to reiterate the work the Trust has been doing. It parallels some other fact sheets that
have come out about other phosphate mines under CERCLA. Fact sheets going forward is
encouraged and would be helpful for the community. I would advise using the Caribou
County Sun to channel information to the community. The community loves to read the
paper and it's well read in the broader community. Mailers and newspaper would be great
way to share information.

3.	Have there been any problems with unusual or unexpected activities at the Site, such as
emergency response, vandalism or trespassing?

•	Not aware of any. If it was a problem, I would probably hear about it. What is unique about
the Site is that it's in the county, but abuts the city limits, so we are definitely neighbors.

4.	Are you aware of any changes to state laws or local regulations that might affect the
protectiveness of the Site's remedy?

•	None seen.

5.	Are you aware of any changes in projected land use(s) at the Site?

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•	It's county land, but there is a buffer zone outside city limits that the city and county try to
collaborate and cooperate on. Even though county planning and zoning ordinances apply, the
city's zoning ordinance influence what goes on in that area. The Site is within the area of city
impact. Should be aware of where the county is going and how the city's plan influences the
county's. They are going through a public outreach process and the county is targeting later
this year to adopt their comprehensive plan. The city will piggyback off of that. There will be
more pressure on how the county addresses zoning. Potential redevelopment on portions of
the Site, which will possibly be influenced by the forthcoming comprehensive plan.

6.	Has EPA kept involved parties and surrounding neighbors informed of activities at the Site?

How can EPA best provide site-related information in the future?

•	I commend the Trust and regulatory agencies for sending the fact sheet out. I have heard the
Trust may have an open house, maybe in the summer. If those are well advertised, you'll get
ok attendance; maybe dozens, not hundreds. But interested parties will come out if it's well
advertised.

•	Meshach: how would virtual meetings be received.

i. Face to face is better because you can offer refreshments, which will further
entice participants. Virtual might not provide you an avenue to get more people to
participate. But you could do both. We do both at city council meetings.

•	There is some perception that email is old school, and other social media is more acceptable.
With the next generation, email might not be best way to communicate.

•	Laura: can you please suggest good events or places to share information

i.	Booth at the county fair (first full week in August)

ii.	4th of July - booths to share information (population doubles for this holiday)

7.	Has the community been receiving sufficient technical information from EPA? Has this

information been clear and easy-to-understand? If not, describe the areas where you believe the

community may need assistance understanding and responding to information about the Site?

•	Yes, and continue to build on what you have already done.

8.	How would you describe the community's relationship with EPA and your organization during

the Superfund cleanup process?

•	As resources wane, public outreach goes by the wayside. Would encourage EPA to have
more outreach on a regular basis. This has gone and will go a long way to be consistent with
that.

•	Laura: do you like the Trust's involvement.

i. Yes, it's helpful, let's take advantage of what postal service and other forums
allow for broad communication. Every 6 months or once a year, a fact sheet or
mass mailer would be easy and fairly low cost.

•	Meshach: is there anything that could be changed/added to the fact sheet?

i. The indication that we're getting is that it's very likely that an MNA approach
will be a significant part of the next remedy, which may be another 40 years to
see how cooperative mother nature is going to be. Is there some way to turn those
lemons into lemonade and look at the feasibility of redeveloping a portion of the
Site. Light industrial possibly or commercial development or intermodal hub; all
of the infrastructure is there. Can we take advantage of the economical potential at

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the site sooner rather than later? There are a lot of plusses in or around the site to
help guide the redevelopment.

9.	Do you have any comments, suggestions or recommendations regarding the project?

•	None beyond what has already been provided and is in written response.

10.	Do you consent to have your name included along with your responses to this questionnaire in
the FYR report?

•	Yes.

11.	Is there anyone else who you would suggest we should talk to?

•	County commissioners

•	Other city officials

•	Reach out if you need additional contacts.

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KERR-MCGEE (SODA SPRINGS, ID) SUPERFUND SITE
FIVE-YEAR REVIEW INTERVIEW FORM
Site Name: Kerr-McGee (Soda Springs, ID) Superfund Site

EPA ID: IDD041310707

Interviewer name: Laura Knudsen, with
support by Meshach Padilla

Subject name: Resident (Name Redacted)

Interview date: March 8, 2022

Interview location: Phone

Interview format (circle one): In Person

Interview category: Resident

Interviewer affiliation: EPA

Subject affiliation: Redacted
Interview time: 11AM EDT

Phone Mail Email Other:

1.	What do you know about the former environmental issues at the Site and the cleanup activities
that have taken place to date?

•	I know why the plant was there in the first place, when Kerr-McGee shut down, they ended
up hiring some operators back then at our facility. I believe a fertilizer entity was attempting
to use some of the waste to use as marketable fertilizer, but that didn't pan out. That may
have led to some of the contamination. I understand the site pretty well and was aware of
ROD in 1995 and cleanup efforts that kicked off 2000 and remembers when the plants were
demolished. I knew one of the environmental people that helped with initial capping. At the
time, community assumed that was going to fix it up and wouldn't be concerns. But FYRs
would point out things weren't progressing. Too many FYRs took place before the issue was
addressed. Bankruptcy obviously complicated things. Because of	, I
knew every time they wanted to drill a well in 2014 or 2015, had to punch wells throughout
city to try and track the plume. They got rid of tailings pond and put bulk of waste that
couldn't be removed in the "sarcophagus". From what I have gathered, things have been
proceeding better with the later work that was done past couple years as compared to 2001-
2004. I'm glad to see it's working. Back when (b) (®) , it appeared in some
projections that the Site couldn't be used as Brownfields facility to do something else out
there for 10-20 years. The infrastructure is there; it has rail, gas, electricity, and water. There
needs to be a way to get interested parties to find something worthwhile to put out there.
While I'm glad they recognized still contamination taking place, I hate to see that taken out
of a productive use for another couple of decades. Reuse and redevelopment is an interest at
the site. It's the ideal spot for something. People looking at it may be apprehensive because
of potential liability. Would really like to see it repurposed sooner than 20 years.

2.	What is your overall impression of the project, including cleanup, and maintenance activities (as
appropriate)?

•	I knew a lot of people who worked on it, some of the contractors do work for us. A lot of
work is done in the summer and we'd ask about it and they said it seemed they were doing a
thorough job. And after touring it seemed like they were doing what they were supposed to
do to address the plume. Looking back with 2020 hindsight, it took 15-20 years to figure out
it wasn't doing what it was supposed to do. The tailings pond sitting out there was
presumably causing some issues.

•	Laura: Do others feel similarly?

F-22

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•	I'm probably more cognizant of the site. The rest of the community asks if it's
contaminating the water supply. Water supply wells sit to north and south of the
site. Obviously concern about water source being contaminated. We've been
told there are no issues. Sometimes people don't believe what the government
tells them. That does happen. But the general community was more concerned
about how it's affecting the water. And they said don't drill a well within city
limits and use for cooking.

3.	What have been the effects of this Site on the surrounding community, if any?

•	In general, I think there is some hesitation (not necessarily apprehension), but a bit of
apprehension that people read the documents and it says the public water is safe, but then it
talks about the groundwater and surface water and you get a perception for some that it's
continuing to contaminate and no one is doing anything for the community. It does exist
within certain members of the community, not prevalent. They are concerned about being
next door and being negatively impacted because of it. That is the general perception of
some. And that broad paintbrush affects perception of other facilities, like the one where I
work. We do have a housing shortage here. Even before that, folks that work at facilities here
live in other places because they indicated they don't want to live near a Superfund site. Not
everyone says that, but some think that.

•	Laura: Has anyone mentioned the mailing of the fact sheet?

•	Haven't heard anything, but during the winter in Soda Springs people don't get
together for much more than basketball games, and that doesn't usually come up
since the focus is on the games. EPA could set up a summer public meeting.
Won't get hundreds of people, but could get 20-30 people who are curious and
want to have a better understanding of what's going on.

4.	Have there been any problems with unusual or unexpected activities at the Site, such as

emergency response, vandalism, or trespassing?

•	I don't believe there has been any. It's outside of the city limits, so county sheriff would deal
with that. I'm not aware of any.

5.	Do you and others you know in the community feel well-informed regarding the Site's activities

and remedial progress? If not, how might EPA convey site-related information in the future?

•	Laura: can you talk about EPA being a trusted source in the community? For example, the
water issue and not trusting the government.

•	For various reasons, regulations coming from farm service agency, or USD A, or
other agencies, but people, in their minds, think it's EPA coming after them. I
don't think every citizen in Soda Springs feels that way, but generically, various
farmers have dealt with chemicals and they blame the EPA. Perception is
reality.

•	I feel well informed because (b) (6)	. Most in community have a basic
understanding that yes, they made something out there, it contaminated the water and the
EPA and others are trying to clean it up. State has a new rule that county and cities need a
comprehensive plan for growth, housing, etc., including hazardous or unsafe areas within
your city or county. City updated theirs to mention industrial sites adjacent to the city that
have contamination and plan indicates the city works with them to expedite cleanup. That
comprehensive plan included an online poll of what do people want to see in the plan; they
had to use leading questions. But they got at least a hundred people to respond.

6.	How do you receive information regarding any aspects of the project?

•	Do you use social media? If so, which kinds of social media?

•	Do you get information through a computer, smart phone, word of mouth or other?

F-23

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• What newspapers, websites, TV, or radio stations do you normally use?

•	City has a Facebook page, Community 41 1 or something, (b) (6)

1 think the county has a Facebook
page, I know EPA has a website. And the Trust is working on a new one. Social media is
good way to share information. The local paper, Caribou County Sun - I think everyone
reads that and you've included info there in the past. No real local radio station. The
Pocatello TV stations broadcast over here, so if people have over the air antenna or on
streaming, might be seen on local news if shared. Not everyone reads the mailers, and if it's
an envelope that says EPA, they may not take the time to open it and it may go directly in the
trash. A 6x9 mailer, postcard with info directly seen when they get the mail, might have more
people reading it. A lot of information is shared by word of mouth. Didn't get much email
communication, usually read in the Sun or see it on Facebook is what gets people to ask
questions or come out to attend something.

An online survey might be useful. Don't make it too long. If you have the right
questions, people could bang through it in 3-5 minutes, might get good feedback. End
with a blank box to allow other questions.

Has the community been receiving sufficient technical information from EPA? Has this
information been clear and easy-to-understand? If not, describe the areas where you believe the
community may need assistance understanding and responding to information about the Site?

•	Probably adequate for the general product. Anything more complex and people might not
understand. Would be helpful to give people information about water quality.

Do you have any comments, questions, suggestions or recommendations regarding any aspects
of the project?

•	Let's get it back to productive use sooner rather than later.

Is there anyone else who you would recommend that we speak with as we continue with the
Five-Year Review and the Community Involvement Plan for the Kerr-McGee Chemical Corp.
(Soda Springs Plant) Superfund Site?

•	(Names Redacted)

May we follow-up with you if we have any clarifying questions as we review the information
you have provided to us today?

•	Yes, no problem.

F-24

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Kerr-McGee (Soda Springs, ID) SUPERFUND SITE
FIVE-YEAR REVIEW INTERVIEW FORM

Site Name: Kerr-McGee (Soda Springs, ID) Superfund Site

EPA ID: IDD041310707

Interviewer name: Meshach Padilla

Interviewer affiliation: EPA

Subject name: Resident (Name Redacted)

Subject affiliation: Redacted

Interview date: March 17, 2022

Interview time: 1:00PM EDT

Interview location: Phone

Interview format (circle one): In Person Phone Mail Email Other:

Interview category: Resident

May have a potential conflict. I live within cily limits, oil the south end. I have a domestic well,
tasted a metallic taste a week ago Sunday (b) (6)	(north of us). He also has a metallic taste - ran

samples up to a lab in Pocatello - high E. coli and coliform. But does not explain the metallic taste. We
had them run some heavy metals and other contaminants. We are within the molybdenum plume. New
cows across the street could explain ecoli. We are hauling water now. We had this metallic taste two
years ago as well but there was some lag time with getting results.

1.	What do you know about the former environmental issues at the Site and the cleanup activities
that have taken place to date?

•	I have reviewed the fact sheet that was sent out. Some of my background is the land just
below Kerr-McGee (Kelly Park, used to be Finch Ranch), (b) (6)

I am familiar with Kerr-McGee quite a bit that date way back (b) (6)

I am likely more familiar than some about the Superfund background.

2.	What is your overall impression of the project, including cleanup, and maintenance activities (as
appropriate)?

•	They got in gear a few years ago. It was stagnated until recently. Initially when they first
proposed the cleanup, there were a couple of us opposed to the type of cleanup they were
doing. They were going to line some of the materials and we were concerned that it wasn't a
permanent fix. We were told it was the best science at the time, and we countered that
hauling it away to a hazardous waste landfill would have been more thorough. That is water
under the bridge, there seems to be quite a lag between then and five years ago. Greenfield
Trust got more involved recently and have done a pretty good job. I am pleased that they
have been very aggressive over the last approximately 5 years.

3.	What have been the effects of this Site on the surrounding community, if any?

•	I think a cloud hanging over it that it's a Superfund site. We had all of the old buildings (now
gone) that was an ugly eyesore. We're still dealing with the plumes. They will have to
address with what to do with the land. The bigger thing was that Soda Springs as a
community didn't want to get labeled as a Superfund Site as it has a really bad connotation to
it. It affected us as well as the neighboring industrial facilities (Behr, Monsanto, etc.). And
we have found the plume has migrated further south. Which is a concern with the private
wells in the area; it becomes a public health issue. Monsanto was pro community and pro
environment. They had more money they could spend on cleanup and environment and

F-25

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looking good, but were concerned they were going to get a black eye because of the
Superfund site.

4.	Have there been any problems with unusual or unexpected activities at the Site, such as
emergency response, vandalism, or trespassing?

•	No. I used to walk my dog in the area daily and haven't seen anything. Taking the buildings
down and cleaning up was an excellent idea.

5.	How do you receive information regarding any aspects of the project?

•	Basically from what the agencies send me, whether the Trust or DEQ and sometimes EPA
(not a heavy hitter in this). I have a couple good sources locally that I can talk to that work or
consult in industry, they are helpful with Superfund cleanup. They help fill me in if I have
questions. EPA has come down before and held public meetings that I have attended. They
have been extremely candid once the meeting is over. I ask if there is a health issue and they
say no. I tend to agree with the findings I've seen before. I get the news releases or flyers. I
used that to rewrite a story in the paper in case it gets thrown away at various homes.

•	Do you use social media? If so, which kinds of social media?

a. I don't use social media or the internet. I know it's popular, but most is hateful
and inaccurate and I refuse to participate.

•	Do you get information through a computer, smart phone, word of mouth or other?

a. I do take emails.

•	What newspapers, websites, TV, or radio stations do you normally use?

a. There is not much of a radio station here, but I will plug the newspaper: Caribou
County Sun. Circulation is 2,600. We have a solid readership. 1,300 are
subscribers. There is a certain amount of trust in the community, if we don't talk
politics.

6.	Are you aware of any changes in land use?

•	I can't address the hazardous material that remains, but you are right next to Kelly Park,
which is a great attraction for hiking, skiing, etc. It would be great to consider hiking trails,
foot paths (not motorized vehicles), maybe bike trails, dog park, tie into the Kelly Park
pathways to Kerr-McGee and work over to the Formation Springs view area (to the north and
east of Kerr-McGee). Could be great for locals and visitors. Use the open space so you won't
be disturbing the caps. Would need a trust set up for maintenance. Industry may create
additional, unwanted problems. May want to deed it to the city or the conservancy.

7.	Do you and others you know in the community feel well-informed regarding the Site's activities
and remedial progress? If not, how might EPA convey site-related information in the future?

•	I do, but I am more involved in general. Some community can be confused by the plumes.
People are generally comfortable that it doesn't get into the city water. There are sometimes
fugitive dust issue, but it's being addressed by remedial actions.

•	Occasionally you could have a short meeting at city council - have an EPA spokesperson
update them. Not all night long - just a short 10-15 minute update to talk about where things
are and what has happened and what will happen. Could also be from DEQ. I am a firm
believer in being up front with people. We are used to mining and industry and if there is a
problem, we need to know. What bothers us is what we have missed, but it's the nature of the
beast. We can handle it.

8.	Has the community been receiving sufficient technical information from EPA? Has this
information been clear and easy-to-understand? If not, describe the areas where you believe the
community may need assistance understanding and responding to information about the Site?

•	I think so, I think the mailer was very good. The problem you have is attention spans
anymore. It can't be much more than a text or you might lose people. Those that care and pay

F-26

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attention, like industry engineers, environmental people, there are the ones that need a bit
more information. They can assimilate more hardcore stuff that others may skip over. Not
everyone may have an interest in the more technical information but some of us do. Which is
why updating city council would be good.

Meshach: any updates we should make to the fact sheet?

I like to see the list of things, more on the science end of it personally. But needs
to be written for an average reader, which the flyer did well. Having details on
more technical data is helpful for some of us and people may want to know what
the levels are and how they compare.

9.	Do you have any comments, questions, suggestions or recommendations regarding any aspects
of the project?

•	Great to reuse the land as mentioned above so it's not just sitting there.

10.	Is there anyone else who you would recommend that we speak with as we continue with the
Five-Year Review and the Community Involvement Plan for the Kerr-McGee Chemical Corp.
(Soda Springs Plant) Superfund Site?

•	City Council President Mitch Hart

i. Community has faith in him, and the council, and he is honest. He handles bad
news and takes care of it. A good solid source to keep informed.

11.	May we follow-up with you if we have any clarifying questions as we review the information
you have provided to us today?

•	Absolutely.

F-27

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APPENDIX G - SITE INSPECTION CHECKLIST

FIVE-YEAR REVIEW SITE INSPECTION CHECKLIST



I. SITE INFORMATION

Site Name: Kerr-McGee Chemical Corp. (Soda
Springs Plant) Superfund Site

Date of Inspection: 4/26/2022

Location and Region: Soda Springs, Idaho Region
10

EPA ID: IDD041310707

Agency, Office or Company Leading the Five-Year
Review: EPA

Weather/Temperature: 50s, windv

Remedy Includes: (Check all that apply)



Rl Landfill cover/containment

1 1 Monitored natural attenuation

153 Access controls

1 I Groundwater containment

153 Institutional controls

1 1 Vertical barrier walls

1 I Groundwater pump and treatment



1 1 Surface water collection and treatment



153 Other: Groundwater monitoring



Attachments: ^ Inspection team roster attached

1 1 Site map attached

II. INTERVIEWS (check all that apply)

1. O&M Site Manager Joel Gerhart P.E.

02/24/2022

Name

Title Date

Interviewed 1 1 at site 1 1 at office 1 1 bv phone Phone:

Problems, suggestions 1 1 Report attached:



2. O&M Staff Scott Rigbv

02/18/2022

Name

Title Date

Interviewed 1 1 at site 1 1 at office 1 1 bv phone Phone:

Problems/suggestions 1 1 Report attached:



3. Local Regulatory Authorities and Response Agencies (i.e., state and tribal offices, emergency
response office, police department, office of public health or environmental health, zoning office,
recorder of deeds, or other city and county offices). Fill in all that apply.

Agencv IDEO



Contact Stan Christensen

02/18/2022

Name Title Date Phone No.

Problems/suggestions 1 1 Report attached:



G-l

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Agency Caribou County Commissioner







Contact Brvce Somsen

03/25/2022





Name Title

Date

Phone No.



Problems/sueeestions 1 1 Report attached:







Agency Caribou County







Contact Eric Hobson Director of

Public Safety

Name

Title

03/11/2022
Date

Phone No.



Problems/sueeestions 1 1 Report attached:







Aeencv Soda Serines City Council







Contact Mitch Hart Council

President

Name

Title

03/08/2022
Date

Phone No.



Problems/sueeestions 1 1 Report attached:







Aeencv







Contact







Name Title

Date

Phone No.



Problems/sueeestions 1 1 Report attached:





4.

Other Interviews (optional) 1 1 Report attached:





Lars Peterson, Multistate Trust

Residents

IH. ON-SITE DOCUMENTS AND RECORDS VERIFIED (check all that apply)

1.

O&M Documents







1^1 O&M manual ^ Readily available

Rl Up to date

~ n/a



1^1 As-built drawings ^ Readily available

1X1 Up to date

~ n/a



1^1 Maintenance logs ^ Readily available

1X1 Up to date

~ n/a



Remarks:





2.

Site-Specific Health and Safety Plan ^ Readily available

^ Up to date Q N/A



1^1 Contingency plan/emergency response plan ^ Readily available

^ Up to date |	| N/A



Remarks:





3.

O&M and OSHA Training Records ^ Readily available

Up to date Q N/A



Remarks:





G-2

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4.

Permits and Service Agreements

1 1 Air discharge permit
1 1 Effluent discharge
1 I Waste disposal, POTW
1 1 Other permits:

Remarks:

1 1 Readily available Q Up to date
1 1 Readily available Q Up to date
1 I Readily available Q Up to date
1 I Readily available Q Up to date

[XI N/A
[XI N/A
[XI N/A
[XI N/A

5.

Gas Generation Records

Remarks:

1 1 Readily available Q Up to date

[XI N/A

6.

Settlement Monument Records

Remarks:

1 I Readily available Q Up to date

[XI N/A

7.

Groundwater Monitoring Records

Remarks:

153 Readily available ^ Up to date

~ n/a

8.

Leachate Extraction Records

Remarks:

Rl Readily available Up to date

~ n/a

9.

Discharge Compliance Records

I~1 Air Q Readily available Q Up to date ^ N/A
|~1 Water (effluent) Q Readily available Q Up to date ^ N/A
Remarks:

10.

Daily Access/Security Logs

Remarks:

153 Readily available Up to date

~ n/a

IV. O&M COSTS

1.

O&M Organization

1 1 State in-house
1 1 PRP in-house
1 1 Federal facility in-house

n

1 1 Contractor for state

153 Contractor for Multistate Trust

1 1 Contractor for Federal facility



2.

O&M Cost Records

1 1 Readily available Q Up to date
153 Funding mechanism/agreement in place Q Unavailable
Original O&M cost estimate: 1 1 Breakdown attached

Total annual cost by year for review period if available
From: To: 1 1 Breakdown attached
Date Date Total cost

From: To: 1 1 Breakdown attached
Date Date Total cost



G-3

-------
From:		To:				~ Breakdown attached

Date	Date	Total cost

From:		To:				~ Breakdown attached

Date	Date	Total cost

From:		To:				~ Breakdown attached

Date	Date	Total cost

3. Unanticipated or Unusually High O&M Costs during Review Period

Describe costs and reasons: 	

V. ACCESS AND INSTITUTIONAL CONTROLS El Applicable ~ N/A

A. Fencing

1.	Fencing Damaged	~ Location shown on site map 153 Gates secured I I N/A

Remarks:

B. Other Access Restrictions

1. Signs and Other Security Measures	~ Location shown on site map ^ N/A

Remarks:	

C. Institutional Controls (ICs)

1. Implementation and Enforcement

Site conditions imply ICs not properly implemented	~ Yes ~ No E| N/A

Site conditions imply ICs not being fully enforced	~ Yes ~ No N/A

Type of monitoring (e.g., self-reporting, drive by):	

Frequency:	

Responsible party/agency:
Contact 	

Name Title

Date

Phone no.

Reporting is up to date

1 1 Yes

~ No

[El N/A

Reports are verified by the lead agency

1 1 Yes

~ No

[XI n/a

Specific requirements in deed or decision documents have been met

1 1 Yes

~ No

[XI n/a

Violations have been reported

1 1 Yes

~ No

El N/A

Other problems or suggestions: ~ Report attached

2. Adequacy	~ ICs are adequate	^ ICs are inadequate	~ N/A

Remarks: Institutional controls are not vet inplace, however the Multistate Trust owns all of the Site
property. Institutional controls for groundwater and land use are planned and will be implemented after
the ROD Amendment is issued.

D. General

1. Vandalism/Trespassing ~ Location shown on site map ^ No vandalism evident
Remarks:	

G-4

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2.

Land Use Changes On Site ^ N/A

Remarks:



3.

Land Use Changes Off Site | | N/A





Remarks: Monsanto is building a new rail spur north of the Site along Trail Creek Road and recently



purshcased the (former) (b) (6) Property adjacent to the northeast.



VI. GENERAL SITE CONDITIONS

A.

Roads Kl Applicable | | N/A



1.

Roads Damaged Q Location shown on site map ^ Roads adequate Q N/A



Remarks:



B.

Other Site Conditions





Remarks: Several buildings are located onsite and are in good condition. The fencing surrounding the



waste areas of the Site is also in good condition.





VII. LANDFILL COVERS ^Applicable

~ n/a

A.

Landfill Surface



1

Settlement (low spots) Q Location shown on site map

153 Settlement not evident



Area extent:

Depth:



Remarks:



2

Cracks Q Location shown on site map

Cracking not evident



Lengths: Widths:

Depths:



Remarks:



3

Erosion Q Location shown on site map

53 Erosion not evident



Area extent:

Depth:



Remarks:



4

Holes Q Location shown on site map

53 Holes not evident



Area extent:

Depth:



Remarks:



5

Vegetative Cover ^ Grass

53 Cover properly established



1 1 No signs of stress Q Trees/shrubs (indicate size and locations on a diagram)



Remarks:



6

Alternative Cover (e.g., armored rock, concrete)
Remarks:

M N/A

7

Bulges Location shown on site map

53 Bulges not evident



Area extent:

Height:



Remarks:



8. Wet A re as/Water Damage ^ Wet areas/water damage not evident

G-5

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1 1 Wet areas 1 1 Location shown on site map Area extent:



1 1 Ponding 1 1 Location shown on site map Area extent:



1 1 Seeps 1 1 Location shown on site map Area extent:



1 1 Soft subgrade 1 1 Location shown on site map Area extent:



Remarks:



9

Slope Instability Q Slides Q Location shown on site map



1^1 No evidence of slope instability





Area extent:





Remarks:



B.

Benches Q Applicable ^ N/A





(Horizontally constructed mounds of earth placed across a steep landfill side slope to interrupt the slope in
order to slow down the velocity of surface runoff and intercept and convey the runoff to a lined channel.)

C.

Letdown Channels Q Applicable ^ N/A





(Channel lined with erosion control mats, riprap, grout bags or gabions that descend down the steep side
slope of the cover and will allow the runoff water collected by the benches to move off of the landfill
cover without creating erosion gullies.)

D.

Cover Penetrations ^ Applicable Q N/A



1

Gas Vents Q Active ^ Passive



1 1 Properly secured/locked Q Functioning Q Routinely sampled

1 1 Good condition



1 1 Evidence of leakage at penetration Q Needs maintenance

~ n/a



Remarks: Installed in the East Waste Repository due to the moisture. Off-gassing is not expected to



occur since the waste material is not volatile.



2

Gas Monitoring Probes





1 1 Properly secured/locked Q Functioning Q Routinely sampled

1 1 Good condition



1 1 Evidence of leakage at penetration Q Needs maintenance

M N/A



Remarks:



3

Monitoring Wells (within surface area of landfill)





1 1 Properly secured/locked Q Functioning Q Routinely sampled

1 1 Good condition



1 1 Evidence of leakage at penetration Q Needs maintenance

[21 N/A



Remarks:



4

Extraction Wells Leachate





1 1 Properly secured/locked Q Functioning Q Routinely sampled

1 1 Good condition



1 1 Evidence of leakage at penetration Q Needs maintenance

[21 N/A



Remarks: Sump



5

Settlement Monuments Q Located Q Routinely surveyed
Remarks:

[2| N/A

E.

Gas Collection and Treatment I I Applicable 153 N/A



G-6

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F.

Cover Drainage Layer ^ Applicable Q N/A



1

Outlet Pipes Inspected ^ Functioning
Remarks:

~ n/a

2

Outlet Rock Inspected Q Functioning
Remarks:

13 N/A

G.

Detention/Sedimentation Ponds Applicable

N/A

H. Retaining Walls fl Applicable [>3 N/A

I. Perimeter Ditches/Off-Site Discharge ^ Applicable

~ n/a

1.

Siltation Q Location shown on site map

15^1 Siltation not evident



Area extent:

Depth:



Remarks:



2.

Vegetative Growth Q Location shown on site map
1 1 Vegetation does not impede flow

IEI N/A



Area extent:

Type:



Remarks:



3.

Erosion Q Location shown on site map

15^1 Erosion not evident



Area extent:

Depth:



Remarks:



4.

Discharge Structure Q Functioning
Remarks:

[XI n/a



VIH. VERTICAL BARRIER WALLS

I"! Applicable 153 N/A

IX. GROUNDWATER/SURFACE WATER REMEDIES ~ Applicable N/A

X. OTHER REMEDIES

If there are remedies applied at the site and not covered above, attach an inspection sheet describing the physical
nature and condition of any facility associated with the remedy. An example would be soil vapor extraction.

XI. OVERALL OBSERVATIONS

A.

Implementation of the Remedy





Describe issues and observations relating to whether the remedy is effective and functioning as designed.
Begin with a brief statement of what the remedy is designed to accomplish (e.g., to contain contaminant
plume, minimize infiltration and gas emissions).



The goal of the implemented remedv was to restore impacted groundwater to meet PSLs. Remedial
activities from 1997 through 2004 included reclamation of several ponds, creation of on-site repositories
and lined ponds and capping. Starting in 2015 and 2016. the Multistate Trust, under oversight of EPA and



in consultation with IDEO. completed site investigation activities and studies to fully characterize the
extent of contamination in support of the development of an FFS and ROD Amendment. Concurrently
with these investigation activities, the Multistate Trust also performed removal actions to reduce risk to
human health and the environment and removed a large amount of source material that was resulting in
impacts to groundwater on and off-site. There are currently two plumes (vanadium and molybdenum)
extending off-site and groundwater concentrations are well above PSLs. The Multistate Trust submitted a
draft FFS to EPA and IDEO in 2021 and anticipates it will be finalized in 2022. EPA will then select an

G-7

-------
amended remedy for the Site in a ROD Amendment.

B.

Adequacy of O&M



Describe issues and observations related to the implementation and scope of O&M procedures. In
particular, discuss their relationship to the current and long-term protectiveness of the remedy.



O&M is adeauate and no issues were observed.

C.

Early Indicators of Potential Remedy Problems



Describe issues and observations such as unexpected changes in the cost or scope of O&M or a high
frequency of unscheduled repairs that suggest that the protectiveness of the remedy may be compromised
in the future.



None.

D.

Opportunities for Optimization



Describe possible opportunities for optimization in monitoring tasks or the operation of the remedy.



None.

Inspection Roster:

Zoe Lipowski, EPA RPM

Stan Christensen, IDEQ

Nick Nielsen, IDEQ

Lars Peterson, Multi state Trust

Alison Cattani, Skeo

Johnny Zimmerman-Ward, Skeo

G-8

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APPENDIX H - SITE INSPECTION PHOTOS

Signage at entrance

Vegetated surface of the East Waste Repository

-------
Surface of the East Waste Repository with East Calcine Area in background

Fencing along the East Waste Repository boundary

H-2

-------
Former 10-Acre Pond, looking north

East Calcine Area/Scrubber Pond Area with Monsanto facility in background

H-3

-------
Monitoring well KM-8

H-4

-------
Evergreen seep surface water sampling location

H-5

-------
APPENDIX I - DATA REVIEW FIGURES AND TABLES7

Figure 1-1: LTM Groundwater and Surface Water Monitoring Network

-------
Figure 1-2: 2021 Groundwater Elevations and Potentiometric Contours

-------
Figure 1-3: October 2021 Arsenic Concentrations

EXPLANATION

Arsenic Concentration (M9"-)

o

<1

•

1 - 10 {< EPA MCL)



10-50 (> EPA MCL)

•

» 50 (> ROD PSL)

FIAB West
Transect

E 6th North Transect

M0.MS4NT0

October 2021 Arsenic

1-3

-------
1-4

-------
Figure 1-5: October 2021 Manganese Concentrations

EXPLANATION

Manganese Concentration (mq^L)

e

<50

•

50 - 180 (< ROD PSL)



180-430 (> ROD PSL)

•

> 430 (> EPA Tapwater RSL)

MOTES:

CMT = continuous multichannel tubing

SRI = Supplemental Remedial Investigation

RSL = EPA Tapwater Regional Screening Level

PSL = Project Screening Level

ROD - EPA Record of Decision

FIAB = Former Industrial Area Boundary

2019 aerial imagery from

National Agricultural Imagery Program

(NAIP).

CMT well values are
maximum observed at all depths.

Groundwater concentrations are dissolved;
surface water concentrations are total.

AOC-1
Transect

Former Industrial Area
Boundary (FIAB) Transect

MOJISANTO

HOOPER ROAD

October 2021 Manganese

1-5

-------
Figure 1-6: October 2021 Molybdenum Plume

iteiiKil

1-6

-------
Figure 1-7: October 2021 Vanadium Plume

1-7

-------
Table 1-1: 2021 Groundwater Monitoring Results





















Total Petroleum























Hydrocarbons -









Arsenic

Lithium

Manganese

Molybdenum

Vanadium

Diesel Range

Tri butyl





QC Sample

(Dissolved)

(Dissolved)

(Dissolved)

(Dissolved)

(Dissolved)

Organics

Phosphate

Location

Date

Type

P«A



Pg/L



PgA



PgA



Pg/L



mg/L



Pg/L



KM-1

6/10/2021



0.6



7.5



0.22

U

10.5



59.6











KM-2

6/10/2021



7.5



74.4



33



526



3590











KM-4

6/8/2021



3.8



48.5



27.9



534



2140











KM-6

6/9/2021



2.9



423



101



464



3190











KM-7

6/8/2021



3.6



14



180



451



2880











KM-8

6/14/2021



48.5



1780



2950



26300



14300



0.535



140



KM-8

6/14/2021

Duplicate

46.9



1650



2900



24100



13100



0.593



160



KM-9

6/14/2021



0.83



12.9



4.7



76.4



237



0.506







KM-10

6/10/2021



0.19

J

6.6



0.22

U

2.9



4.4











KM-12

6/16/2021



0.76



30.2



24.6



139



266











KM-15

6/15/2021



1.7



37.5



32.7



239



866











KM-16

6/9/2021



2.9



41,8



64.9



462



2230











KM-17

6/9/2021



0.7

U

15.5



10.2



280



87.7











KM-18

6/14/2021



1.3



34



27.5



214



619











KM-21

6/9/2021



0.29

J

6.9



0.22

U

8



25.6











KM-22

6/11/2021



0.77



7.7



0.22

U

12.9



216











KM-24

6/8/2021



5.6



30.9



102



422



15100



0.0859

J+





KM-25

6/10/2021



0.14

u

6.2



0.22

u

2.1



1











KM-28

6/10/2021



1



36.6



9.3



116



303











KM-29

6/8/2021



3.9



17.4



6.5



214



2200











KM-29

6/8/2021

Duplicate

3.5



15.9



5.8



195



1990











KM-30

6/9/2021



1.7



643



63.4



168



1980











KM-31

6/9/2021



0.7

u

6.7



1.1

u

1.9

J

1.3

U









KM-35

6/8/2021



0.43

J

8.2



0.24

J

5.8



53











KM-36

6/9/2021



0.7

u

6.9



1.1

u

6.8



1.3

U









KM-37

6/16/2021



0.38

J

10.7



0.5

u

1.5



1.4











KM-38

6/10/2021



0.36

J

10.8



0.22

u

9.5



1.2











KM-43

6/11/2021



0.38

J

11.3



0.4

J

162



3.5











KM-43

6/11/2021

Duplicate

0.41

J

11.5



0.42

J

166



3.4











KM-44

6/8/2021



133



23.9



2.5



398



7970











KM-45

6/16/2021



0.26

J

15.5



0.22

u

160



1.1











KM-45

6/16/2021

Duplicate

0.25

J

153



0.22

u

158



1.1











KM-47

6/11/2021



0.55



94.5



1110



0.31

J

0.27

U









KM-48

6/16/2021



19



145



572



0.53



0.28

J









Tl-101-01

5/27/2021



1.4



15.1



0.84



39.4

J

388

J-









Tl-101-02

6/14/2021



1



15.6

J

0.22

u

41.8



339











Tl-101-03

6/15/2021



0.74



10.8



0.73



19.6



170











Tl-101-04

6/15/2021



0.85



10.5



1.8



19.6



157











1-8

-------




















Total Petroleum

























Hydrocarbons -











Arsenic

Lithium

Manganese

Molybdenum

Vanadium

Diesel Range

Tri butyl





QC Sample

(Dissolved)

(Dissolved)

(Dissolved)

(Dissolved)

(Dissolved)

Organics

Phosphate

Location

Date

Type

Hg/L



Hg/L



Hg/L



Hg/L



Hg/L



mg/L



Hg/L



Tl-101-05

6/15/2021



0.66



10



0.32

j

13.8



140











Tl-101-06

5/27/2021



0.73



9



6



26.6



6.3











Tl-102-01

6/9/2021



2.4



21.5



39.4



238



1490











Tl-102-02

6/10/2021



2.1



22.8



39.4



251



987











Tl-102-03

6/10/2021



5.1



40.1



173



80.1



0.96

J









Tl-102-04

6/10/2021



1.2



19.4



162



26.7



0.27

U









Tl-102-05

6/9/2021



0.73



22.7



68.6



3.9



3.5











Tl-102-06

6/9/2021



0.2

J

20.8



15.5



3.3



1.3











Tl-104-01

WELL DRY NO SAMPLE





























Tl-104-02

WELL DRY NO SAMPLE





























Tl-104-03

5/25/2021



1.7



22.9



402



5.9



0.58

J

0.0511



0.31

U

Tl-104-04

6/7/2021



2.9



27.7



544



8.3



0.75

J









Tl-104-05

WELL DRY NO SAMPLE





























Tl-104-06

5/27/2021



7.1



35.2



61.4



34.9



0.27

u









Tl-105-01

5/26/2021



1.6

J

30.1



15.7



265



595



0.0526

U

0.32

U

Tl-105-02

5/25/2021



1.7

J

35.5



14.5



289



573











Tl-105-03

5/25/2021



1.2



27.5

J

4.8



397



ISO



0.037

J

0.31

U

Tl-105-04

5/25/2021



1.4

U

28.6



241



3.6

J

2.7

u









Tl-105-05

5/25/2021



0.76



32.6



243



2.2



0.27

u

0.0392

J

0.31

U

Tl-105-06

5/26/2021



2.7



54.2



158



1.1



0.27

u









Tl-106-01

5/25/2021



0.91



13



11.1



128



94.9











Tl-106-02

5/25/2021



0.86



12.3



203



158



37.8



0.048

J

0.32

U

Tl-106-03

5/25/2021



1.4

U

13.7



4.4

J

144



68











Tl-106-03

5/25/2021

Duplicate

1.4

U

13.4



4.4

J

142



67.1











Tl-106-04

5/25/2021



0.46

J

12.4



116



8.7



2.9



0.0437

J

0.31

U

Tl-106-05

5/25/2021



1.4

U

13.5



101



42.6



2.7

u









Tl-101-01

WELL DRY NO SAMPLE





























Tl-107-02

5/26/2021



1.4

U

9.1



15.6



61.3



12.8



0.0619



0.31

U

Tl-107-03

5/26/2021



0.72



10.6



3.5



89.9



65.2











Tl-107-04

6/14/2021



0.84



13.6



1.6



130



128



0.0603

J

0.31

U

Tl-107-04

6/14/2021

Duplicate

0.84



13.4



1.5



131



127



0.152

J

0.31

U

Tl-107-05

5/26/2021



1.1



12.4



9.8



115



102











Tl-107-06

5/26/2021



0.79



12.3



8



125



98.5











Tl-107-07

5/26/2021



1.4

U

18.6



2.2

U

253



164



0.0477

U

0.3

U

Tl-108-0'1

5/27/2021



0.41

J

9.3



6.6



95.2



17.5











Tl-108-02

6/10/2021



1.2



10.3



226



137



4.5











Tl-108-03

5/27/2021



0.7



9.4



1.2



2.6



1.3











Tl-108-04

5/27/2021



1.2



30



105



12.3



0.27

u









1-9

-------




















Total Petroleum























Hydrocarbons -









Arsenic

Lithium

Manganese

Molybdenum

Vanadium

Diesel Range

Tri butyl





QC Sample

(Dissolved)

(Dissolved)

(Dissolved)

(Dissolved)

(Dissolved)

Organ ics

Phosphate

Location

Date

Type

PgA



Pg/L



Pg/L



pg/L



Pg/L



mg/L



Hg/L



Tl-108-05

5/27/2021



0.49

J

27.2



0.33

J

20.8



2.1











Tl-108-06

WELL DRY NO SAMPLE





























11-109-01

5/24/2021



0.25

J

6.3



0.28

J

1.8



1.2











Tl-109-02

5/24/2021



0.38

J

6.4



0.44

J

2.1



0.85

J









Tl-109-03

5/24/2021



0.33

J

7.4



0.38

J

1.6



0.95

J









Tl-109-04

5/24/2021



2

J

29.9



185



6.9



2.7

U









Tl-109-05

6/10/2021



0.83



48.5



81.4



2.2



0.27

U









Tl-109-06

WELL DRY NO SAMPLE





























Tl-109-07

WELL DRY NO SAMPLE





























T2-201-01

5/28/2021



0.52



7.4



0.39

J

10.5



103











T2-201-04

6/7/2021



0.59



7.8



0.43

J

7.7



89.7











T2-202-01

6/8/2021



120



246



436



9710



53900



0.161

J+





T2-202-05

6/8/2021



0.34

J

12.6



52.8



2.4



1.8











T2-203-01

6/8/2021



14.8



80.5



89.3



2530



1010











T2-203-01

6/8/2021

Duplicate

14.8



72.8



86.7



2550



956











T2-203-06

6/8/2021



3



14



28.1



176



3500











T2-204-01

6/9/2021



35.2



88.8



2400



3090



250000



0.297



0.31

U

T2-204-02

6/8/2021



0.86

J

8.4



181



231



186











T2-204-05

6/8/2021



1-8

J

20



125



57.6



2-1

J









T2-205-02

6/8/2021



0.7



10.4



72.4



122



92



0.0593

J+





T2-206-01

6/8/2021



1.4

J

30.6



60.2



231



721











T2-206-01

6/8/2021

Duplicate

1.4

J

30.9



59.9



233



730











T2-206-04

6/8/2021



0.7

U

8.3



1.1

U

34.3



62.7











T2-207-02

6/9/2021



2.3

J

66.9



39



398



547











T2-207-04

6/8/2021



0.7

U

7.4



1.1

U

25.8



19.3











T2-208-01

6/7/2021



1



13.7



1.1

u

34.9



294











T2-208-02

5/25/2021



1.4

U

12



10.7



68.2



223











T2-208-03

5/27/2021



0.89



10.1



1.3



45.6



167











T2-208-04

5/27/2021



0.8



9.3



1



32.1



158











T2-208-05

5/27/2021



0.73



9.3



1



38.2



134











T2-209-01

5/27/2021



5.4



168



1550



1650



1940











T2-209-02

5/27/2021



4.8



256



284



8200



1660











T2-209-03

6/14/2021



2.8

J

281



2530



12900



56.8







4



T2-209-04

5/27/2021



1.4



18.5



164



451



142











T2-209-05

5/27/2021



0.84



9.5



4.5



25.2



23.2











T2-209-06

5/28/2021



0.64



8.2



0.68



12.6



62.1











T2-210-01

6/9/2021



3.5



61



46.7



471



2490











T2-210-02

5/28/2021



3.5



43.4



28.9



457



2420











I-10

-------
















Total Petroleum



















Hydrocarbons -









Arsenic

Lithium

Manganese

Molybdenum

Vanadium

Diesel Range

Tri butyl





QC Sample

(Dissolved)

(Dissolved)

(Dissolved)

(Dissolved)

(Dissolved)

Organ ics

Phosphate

Location

Date

Type

Hg/L



Hg/L



Hg/L



Hg/L



M€/L



mg/L



Hg/L



T2-210-03

5/28/2021



2



47.4



977



883



116











T2-210-04

6/9/2021



1.6

J

21.6



2.4

J

162



914



0.0304

J





T2-210-04

6/9/2021

Duplicate

1.5

J

20.4



2.2

J

154



873



0.03

J





T2-210-05

6/9/2021



2.1



20.8



7.2



154



676











T2-210-06

5/28/2021



0.9



10.3



4



43.6

J

159











T2-211-01

6/14/2021



3.4



44.9



67.6



727



1730











T2-211-02

6/11/2021



3.4



41,7



19.1



444



2040











T2-211-03

6/14/2021



0.76



24.1



34.8



59.7



117











T2-211-04

6/14/2021



0.57



35.1



316



7.8



0.27

U









T2-211-05

6/14/2021



1.2



70.9



69.5



15.7



0.59

J









T2-211-06

WELL DRY NO SAMPLE





























T2-212-01

6/9/2021



1.3

J

10.9



73.2



134



4.8

J

0.0286

J





T2-212-02

6/9/2021



1.3



13.3



119



18.2



4.7

J









T2-212-03

6/9/2021



0.85



12.6



638



9.9



2.6

J









T2-212-04

6/9/2021



1.6



11.2



54.1



42.2



186











T2-212-05

6/9/2021



0.9



16.1



0.67



72.8



251











T2-212-06

6/9/2021



0.97



15



17.7



58.3



49.2











T2-213-01

6/11/2021



1.7



17.1



11.7



161



1090











T2-213-02

6/10/2021



1.8



16.4



20.3



187



1000











T2-213-03

6/15/2021



4.7



9.1



422



36.9



1.7











T2-213-04

6/10/2021



1.8



16.2



26.1



187



1030











T2-213-05

6/11/2021



1.7



16.1



4.6



206



943











T2-213-05

6/11/2021

Duplicate

1.7



16.9



4.4



211



966











T2-214-01

6/11/2021



1.3



16.2



12.3



152



593











T2-214-02

6/10/2021



1



14.1



17



307



191











T2-214-03

6/10/2021



1



10.1



59.9



207



9.1











T2-214-04

6/11/2021



1.3



15.1



127



212



2.7











T2-214-05

6/10/2021



1



18.6



130



5.7



2.9











T2-214-06

6/16/2021



0.51



10.7



0.75



62.7



19.7











T2-215-01

6/9/2021



7



114



345



1710



3490











T2-215-02

6/10/2021



1.2



28.6



14.9



435



223











T2-215-02

6/10/2021

Duplicate

1.1



28.5



15.5



441



227











T2-215-03

6/10/2021



0.72



20.7



4.3



246



118











T2-215-04

6/10/2021



0.56



16.1



28.1



276



63.2











T2-215-05

6/10/2021



0.67



9.4



0.54



33.3



124











T2-216-01

6/8/2021



6.3



465



44.6



7290



641



0.148

J+





T2-216-02

6/8/2021



0.39

J

23.5



79.4



2050



6.6











T2-216-03

6/8/2021



0.58



33.6



334



537



6.4











1-11

-------






















Total Petroleum

























Hydrocarbons -









Arsenic

Lithium

Manganese

Molybdenum

Vanadium

Diesel Range

Tri butyl





QC Sample

(Dissolved)

(Dissolved)

(Dissolved)

(Dissolved)

(Dissolved)

Organ ics

Phosphate

Location

Date

Type

Hg/L



Ug/L



Hg/L



Hg/L



Hg/L



mg/L



Hg/L



T2-216-04

6/8/2021



0.25

J

6.1



0.22

U

3.4



1.4











T2-216-05

6/8/2021



0.49

J

5.9



031

J

2.9



1.8











T2-217-01

WELL DRV NO SAMPLE





























T2-217-02

6/9/2021



4.3



548



1160



7560



12.7



0.631



570



T2-217-02

6/9/2021

Duplicate

4.3



581



1190



7200



13.1



0.609



760



T2-217-03

6/9/2021



0.35

J

7.1



19.3



5.2



2











T2-217-04

6/9/2021



0.26

J

6.3



0.25

J

2



1.1











T2-217-05

6/9/2021



0.33

J

7.2



6.8



2.7



0.78

J









T2-219-01

6/10/2021



0.38

J

60,6



20.9



400



2.5











T2-219-02

6/10/2021



0.24

J

6.7



0.34

J

1.7



0.95

J









T2-219-02

6/10/2021

Duplicate

0.25

J

6.4



2.2

J

1.7



0.94

J









T2-219-03

6/9/2021



0.26

J

6.8



0.36

J

2.1



1.3











T2-219-04

6/10/2021



0.3

J

6.4



2.2

J

2.8



1











T2-219-05

6/11/2021



1.3



8.2



101



4.9



1.1











T2-220-01

6/9/2021



0.41

J

6.7



0.92



2.9



1











T2-227-03

WELL DRY NO SAMPLE





























T2-227-04

6/15/2021



1.4



20.4



108



322



99.1











T2-228-03

5/26/2021



1.5



21.9



15.6



271



154











T2-228-05

5/26/2021



1.4

U

15.4



21.4



392



2.8

J





0.31

U

T2-229-02

6/15/2021



1.1



15.9



4.4



148



110











T2-229-06

6/15/2021



0.66



16.9



10.4



83.3



5.2











T2-230-02

6/9/2021



2.3



201



179



9.9



0.27

U









T2-231-02

6/14/2021



1.3



16.8



93.7



50.2



3.3



0.0901

J





T2-232-03

5/24/2021



5.3

J

207



278



8.2

J

5.3

U









T2-233-01

6/14/2021



1.4



19.7



153



148



18.5











T2-233-01

6/14/2021

Duplicate

1.6



20.2



146



136



16.4











T2-233-04

6/14/2021



1.7



23



320



260



4.2











T2-233-07

6/14/2021



1.9



70.3



40.3



91.2



2.3











T2-234-01

6/14/2021



0.73



15.2



0.24

J

84.1



5.9











T2-234-03

6/14/2021



0.88



15.4



22.5



176



27.8











T2-234-03

6/14/2021

Duplicate

0.87



15.1



22.6



174



27.7











T2-234-06

6/14/2021



1.3



19.5



349



214



8.8











T2-235-02

5/24/2021



1.4

U

11.9



2.2

u

79



3.8

J









T2-235-05

5/24/2021



1.4

u

15.1



20.7



139



3.8

J









T2-236-04

5/24/2021



1.4

u

13.6



5

u

47.1



2.7

U









T2-238-02

6/15/2021



0.32

J

13



35



208



2











T2-238-02

6/15/2021

Duplicate

0.29

J

12.4



33.2



195



1.9











T2-238-05

6/15/2021



0.53



14.3



6.2



214



1.9

































Total Petroleum

























Hydrocarbons -









Arsenic

Lithium

Manganese

Molybdenum

Vanadium

Diesel Range

Tri butyl





QC Sample

(Dissolved)

(Dissolved)

(Dissolved)

(Dissolved)

(Dissolved)

Organ ics

Phosphate

Location

Date

Type

Mg/L



pg/L



pg/L



pg/L



Pg/L



mg/L



Ug/L



T2-240-02

6/15/2021



7.1



38.4



866



25.9



0.28

J









T2-240-03

6/15/2021



8



89.1



231



58



0.27

U









T2-240-03

6/15/2021

Duplicate

8.1



88.5



232



58.6



0.27

U









T2-240-07

6/15/2021



1.4



72.5



66.5



9.1



0.27

U









T2-242-01

6/11/2021



0.92



15.4



1.2



34.9



349











T2-242-03

6/14/2021



1.2



12.4



161



40.2



178











T2-242-06

6/14/2021



0.64



7.5



2.5



7.9



68.1











T2-243-01

6/14/2021



0.92



18.8

J

5.8



35.6



357











T2-243-03

6/11/2021



2.5



11.7



28.3



21.9



184











T2-244-02

5/25/2021



1.4

U

14



2.2

U

26.1



312











T2-244-04

5/25/2021



1.4

U

9



2.2

U

23.4



105











T2-245-01

5/24/2021



1.4

U

8.4



2.2

U

15.1



227











T2-245-01

5/24/2021

Duplicate

1.4

U

8.2



2.2

U

14.6



224











T2-245-04

5/24/2021



1.6

J

12.7



42



11.2



29.9











1-12

-------


















Total Petroleum





















Hydrocarbons -









Arsenic

Lithium

Manganese

Molybdenum

Vanadium

Diesel Range

Tri butyl





QC Sample

(Dissolved)

(Dissolved)

(Dissolved)

(Dissolved)

(Dissolved)

Organics

Phosphate

Location

Date

Type

Hg/L



W?/L



Hg/L



W5/L



Hg/L



mg/L



Hg/L



KM-1

9/30/2021



0.5

J

7.9



0.31

J

9



44.9











KM-2

10/4/2021



7.2



72.2



30.7



514



2980











KM-2

10/4/2021

Duplicate

7.6



76.3



32.2



538



3140











KM-4

9/30/2021



2.9



41.9



16.8



500



1330











KM-6

9/29/2021



3.1



44.6



97.7



441



2930











KM-7

9/29/2021



5



15.6



246



633



4140











KM-8

10/4/2021



73.7



1900



2470



26500



21200



0.504

J

0.29

U

KM-9

10/4/2021



1



15



6.3



88.2



261



0.47

J





KM-10

10/6/2021



0.21

J

7.4



0.5

U

2.9



5.4











KM-12

10/4/2021



1.2



33.3



21.6



170



448











KM-15

10/5/2021



1.9



43.5



36.4



250



891











KM-16

10/4/2021



2.6



37.2



50.2



384



1850











KM-16

10/4/2021

Duplicate

2.7



37.7



51



390



1880











KM-17

10/1/2021



0.25

J

14



5.1



238



35.9











KM-18

10/5/2021



1.3



33.3



27.1



200



594











KM-21

9/29/2021



0.31

J

6.7



0.2

U

6.8



24











KM-22

10/5/2021



0.75



8.1



0.5

U

12.8



226











KM-24

9/29/2021



7.3



38.9

J

158



765



22000



0.146







KM-25

9/29/2021



0.15

J

6.6



0.2

U

2.1



0.97

J









KM-28

10/4/2021



1.2



35.6



11.1



121



299











KM-29

9/29/2021



3.6



16.5



5.6



200



2000











KM-30

10/1/2021



1.6



52



55.9



115



1570











KM-31

10/1/2021



0.18

J

7.3

J

0.2

U

2



1.2











KM-35

10/5/2021



0.43

J

7.6



0.2

U

5.9



57.1











KM-36

10/5/2021



0.2

J

6.2



0.5

U

6.8



1.1











KM-37

10/5/2021



0.45

J

10.1



0.5

U

1.6



1.3











KM-38

10/6/2021



0.4

J

12.2



0.2

U

9.4



1.2











KM-43

10/5/2021



0.44

J

13.1



0.54



176



4.1











KM-44

9/28/2021



14.1



24.8

J

2.8



378



8360











KM-45

10/5/2021



0.32

J

14.2



0.5

U

157



1.1











KM-45

10/5/2021

Duplicate

0.3

J

13.9



0.55

J+

155



1











KM-47

10/6/2021



0.5



109



1230



0.18

J

0.16

U









KM-48

10/6/2021



25



141



576



0.56



0.17

J









1-13

-------


















Total Petroleum























Hydrocarbons -











Arsenic

Lithium

Mangan ese

Molybdenum

Vanadium

Diesel Range

Tri butyl





QC Sample

(Dissolved)

(Dissolved)

(Dissolved)

(Dissolved)

(Disso

ved)

Organics

Phosphate

Location

Date

Type

Pg/L



Pg/L



Pg/L



Pg/L



Pg/L



mg/L



Pg/L



Tl-101-01

9/30/2021



1.1



15.5



0.6



35.1



374











Tl-101-05

9/30/2021



0.57



9.9



0.3

J

15.8



159











Tl-101-06

9/30/2021



0.68



12.8



6.1



29.3



3.9











Tl-102-01

9/29/2021



2.4



21.1



95.3



224



1270











Tl-104-03

10/5/2021



1.5



23



407



5.9



0.46

J

0.0246

U

0.29

U

Tl-105-01

10/4/2021



1.6



31.8



14.5



288

J+

623



0.0246

UJ

0.3

U

Tl-105-03

10/4/2021



1.2



31.5



7.9



421



1S3



0.0459

J

0.31

U

Tl-105-05

10/5/2021



0.85



37.5



214



2.8



0.23

J

0.0335

J

0.28

U

Tl-106-01

10/4/2021



0.91



12.6



11.2



138



97.7











Tl-106-02

10/4/2021



0.78



14.8



161



177



46.9



0.0246

UJ

0.29

U

Tl-106-02

10/4/2021

Duplicate

0.96



12.9



192



206



55



0.0246

UJ

0.29

U

Tl-106-04

10/4/2021



0.37

J

13.4



119



11.5



3.7



0.032

J

0.29

U

Tl-107-02

10/4/2021



0.39

J

8.6



2.6



70.6



14



0.0246

UJ

0.3

U

Tl-107-04

10/4/2021



0.86



13.6



1.5



142



129



0.0246

UJ

0.3

U

Tl-107-04

10/4/2021

Duplicate

0.86



12.5



1.6



143



132



0.0246

UJ

0.3

U

Tl-107-07

10/4/2021



1.4



18.9



1



289

J+

177



0.0246

UJ

0.3

U

Tl-108-01

9/30/2021



0.42

J

9.5



2



97.7



19.6











Tl-108-03

9/30/2021



0.68



11.1



3.2



2.8



1.3











Tl-109-01

9/30/2021



0.22

J

6.6



0.43

J

2.1



1.4











T2-201-01

9/28/2021



1.2



8.7



0.64



15.7



143











T2-201-04

9/28/2021



0.55



7.8



0.98



7.6



97.2











T2-202-01

WELL DRY NO SAMPLE





























T2-202-05

9/28/2021



0.34

J

10.3



29



2

J

3











T2-203-01

9/28/2021



15



75.1



97.8



2270



836











T2-203-01

9/28/2021

Duplicate

14.4



70.2



95.4



2450



891











T2-203-06

9/28/2021



3.2



13.9



184



183



3250











T2-204-01

9/28/2021



40.7



108



2720



3560



213000



0.277



0.36

U

T2-204-02

9/28/2021



0.96



8



155



228



196











T2-204-05

9/28/2021



1.3



14.7



92.6



36



1.9











T2-205-02

9/29/2021



0.82



9.5



65.2



115



112



0.044

J





T2-206-01

9/28/2021



1.5



34.1



57.1



209



648











T2-206-04

9/28/2021



0.33

J

8.8



0.72



33.4



59.6











T2-207-02

9/27/2021



2.5



65.5



35.9



381



549











T2-207-04

9/27/2021



0.27

J

7.6



0.5

U

22.3

J

18.1











1-14

-------
















Total Petroleum



















Hydrocarbons -









Arsenic

Lithium

Manganese

Molybdenum

Vanadium

Diesel Range

Tri butyl





QC Sample

(Dissolved)

(Dissolved)

(Dissolved)

(Dissolved)

(Dissolved)

Organics

Phosphate

Location

Date

Type

Pg/L



Pg/L



Pg/L



Pg/L



Pg/L



mg/L



Pg/L



T2-208-01

9/29/2021



0.94



12.9



0.2

U

29.2



296











T2-208-05

9/30/2021



0.85



10



26.4



36.6



141











T2-209-01

9/28/2021



4.7



137



1290



1080



1750











T2-209-01

9/28/2021

Duplicate

4.6



138



1340



1120



1870











T2-209-02

9/28/2021



4.4



223



205



7070



1790











T2-209-03

9/28/2021



3.3



275



2270



13600



82.8







2.4



T2-209-04

9/28/2021



1.7



16.1



181



446



114











T2-209-05

9/28/2021



0.95



10.3



3.2



28.5



28.9











T2-209-06

9/28/2021



0.69



7.9



1.2



12.8



64.6











T2-210-01

9/29/2021



3.1



54.4



41.5



432



2400











T2-210-03

9/29/2021



1.9



40.3



851



718



92.4











T2-210-04

9/29/2021



1.6



21.1



2.3



148



868



0.0246

U





T2-210-05

9/29/2021



1.9



17.9



6.3



133



610











T2-211-01

9/29/2021



3.2



38.2



57.8



624



1650











T2-211-03

9/29/2021



0.77



23



2.8



55.8



121











T2-212-01

10/4/2021



1.3



11.3



79



126



4.8



0.0246

UJ





T2-212-03

9/30/2021



0.67



11.5



402



10.3



2.7











T2-212-05

9/30/2021



0.94



17



0.27

J

75.3



275











T2-213-01

9/29/2021



1.8



18.6



13.9



190



1170











T2-213-03

9/29/2021



4.6



8.4



425



37.3



3.5











T2-213-05

9/29/2021



1.7



15.7



4.8



209



930











T2-213-05

9/29/2021

Duplicate

1.7



15.9



4.6



212



947











T2-214-01

9/29/2021



1.3



15.6



11.4



146



572











T2-214-02

9/29/2021



1



13.8



13.7



288



195











T2-214-05

9/29/2021



0.95



18.1



126



5.4



2.7











T2-215-01

9/29/2021



6.7



105



335



1430



3170











T2-215-05

9/29/2021



0.49

J

8.5



0.2

U

32.8



127











T2-216-01

10/4/2021



6.6



478



59.5



6500



685



0.232

J





T2-216-04

9/30/2021



0.26

J

7



0.2

U

3.3



1.7











T2-216-04

9/30/2021

Duplicate

0.24

J

7.7



0.2

U

3.2



1.6











T2-217-01

WELL DRY NO SAMPLE





























12-217-02

9/29/2021



4.3



784



946



5420



20.2



0.622



790



T2-217-03

9/29/2021



035

J

6.6



12.4



4.5



1.7











T2-219-01

9/29/2021



0.36

J

50



20.1



360



2.7











T2-219-03

9/29/2021



0.15

J

6.3



0.43

J

2.1



1.3











T2-220-01

9/28/2021



0.26

J

6.5



0.75



2.4



1











T2-227-03

10/5/2021



1.8



24.9



4.8



286



272











T2-227-04

10/5/2021



1.4



20.7

J

87.8



299



130











1-15

-------


















Total Petroleum





















Hydrocarbons -









Arsenic

Lithium

Manganese

Molybdenum

Vanadium

Diesel Range

Tri butyl





QC Sample

(Dissolved)

(Dissolved)

(Dissolved)

(Dissolved)

(Dissolved)

Organ ics

Phosphate

Location

Date

Type

Hg/L



Pg/L



Pg/L



Pg/L



Pg/L



mg/L



Hg/L



T2-228-03

10/4/2021



1.5



23.1

J

15

J

244



160











T2-22S-05

10/5/2021



0.81



13.8



19.6



448



3







0.28

U

T2-229-02

10/4/2021



1.1



15



4



143



100











T2-229-06

10/4/2021



0.76



17.1



11.1



86.6



5.3











72-230-02

9/30/2021



1.8



209



199



11.1



0.16

U









T2-230-02

9/30/2021

Duplicate

1.9



212



201



10.9



0.16

U









T2-231-02

10/4/2021



1.3



13.9



65



49.8



3.5



0.0377

J





T2-232-03

10/1/2021



5.4



181



273



7.7



0.22

J









T2-233-01

10/1/2021



2.1



15.7



130



96.1



14.8











T2-233-04

10/1/2021



1.6



21.5

J

268



238



5.4











T2-233-04

10/1/2021

Duplicate

1.6



21.3

J

279



233



5.6











T2-233-07

10/4/2021



1.7



70.7



37.1

J

84.4



2.4











T2-234-01

9/30/2021



0.84



16.4



0.94



91



11.3











T2-234-03

9/30/2021



0.84



14.6



22.7



205



34.5











T2-234-06

10/1/2021



1.6



22.5

J

374



192



6











T2-235-02

9/30/2021



0.4

J

11.5



1.3



81.2



4











T2-235-05

10/4/2021



0.5



14.6



18.5



157



4.3











T2-236-04

10/4/2021



0.51



13.9



1.7

J+

50.2



1.7











T2-238-02

10/1/2021



0.38

J

13.8



37.5



228



2.2











T2-238-05

10/1/2021



0.4

J

13.5



5.4



230



2.1











T2-240-02

10/5/2021



7



37.6



803



23.3



0.16

U









T2-240-03

10/5/2021



9.2



98.3



271



62.3



0.16

u









T2-240-03

10/5/2021

Duplicate

8.9



96.3



266



60



0.16

u









T2-240-07

10/5/2021



1.6



86



76



9.7



0.16

u









T2-242-01

9/30/2021



0.88



14.2



0.76



29.5



308











T2-242-03

9/30/2021



0.92



12.4



165



41.4



219











T2-242-06

9/30/2021



0.53



8.6



1.4



8.6



79.9











T2-243-01

9/30/2021



0.89



19.6



2.6



35.9



369











T2-243-03

9/29/2021



2.6



11.3



17.2



21.5



191





























Total Petroleum





















Hydrocarbons -









Arsenic

Lithium

Manganese

Molybdenum

Vanadium

Diesel Range

Tributyl





QC Sample

(Dissolved)

(Dissolved)

(Dissolved)

(Dissolved)

(Dissolved)

Organ ics

Phosphate

Location

Date

Type

Pg/L



Pg/L



pg/L



Pg/L



Pg/L



mg/L



Pg/L



T2-244-02

9/27/2021



0.86



14.7



0.5

U

24



315











T2-244-04

9/30/2021



1.2



8.4



0.9



25.8



119











T2-245-01

9/27/2021



0.8



7.7



0.5

u

14.4



223











T2-245-04

9/28/2021



1.6



12.7



29.2



11



32.9











FFS-1

9/30/2021



9.7



152



2770



869



189











FFS-1

9/30/2021

Duplicate

10.1



165



3010



877



200











FFS-2

9/30/2021



2.4



86.6



345



677



1910











FFS-3

9/30/2021



3



128



355



1010



3850











PSL
MCL/RSL

























50



IMA



180



180



260



0.730



180



10



40



430



100



86



0.100



5.2



NOTES: J = result qualified as estimated

J- = result qualified as estimated with potential low bias
J«- - result qualified as estimated with potential high bias
U - not detected above the associated value
PSL - piojecl screening level

MCL/RSL = EPA primary maximum contaminant level (MCL) foi arsenic; or lapwater Regional Screening level (RSL) for other constituents
Green shading indicates exceedance of lower criterion (PSL or MCL/RSL)

Yellow shading indicates exceedance of both PSL and MCL/RSL

1-16

-------
Table 1-2: 2021 Surface Water Monitoring Results

Location

City of Soda Springs
Drinking Water
Source

Sample Date

QC Sample
Type

Arsenic (Total)

Lithium (Total)

Manganese
(Total)

Molybdenum
(Total)

Vanadium
(Total)

Hg/L



Hg/l



Mg/L



M-g/i-



Hg/L































Big Spring

No

6/15/2021



0.56



12.1



0.64



101



3.4



Evergreen SW

No

6/15/2021



0.52



12.1



2.1



83.5



59.5



Finch Spring

No

6/15/2021



0.33

J

12.7



0.43

J

76.6



27.5



Finch Spring

No

6/15/2021

Duplicate

0.31

J

12.9



0.35

J

75.1



27.4



Formation Spring

Yes

6/15/2021



0.25

J

6.8



0.24

J

1.4



0.52

J

Kelly Pond

No

6/15/2021



0.28

J

14.8



5.8



41.7



13



Lower Ledger

Yes

6/15/2021



0.15

J

5.9



0.22

u

1.3



0.95

J

Spring 2

Yes

6/15/2021



0.14

U

6.1



0.22

u

1.5



1



Spring 3

No

6/15/2021



0.14

U

6



0.22

u

1.5



0.97

J

Spring 4

Yes

6/15/2021



0.14

U

6



11.2



1.5



0.95

J

Spring A

Yes

6/15/2021



0.21

J

6.4



0.83



1.3



1



Upper Ledger

Yes

6/15/2021



0.14

u

6.1



0.32

J

1.6



0.92

J

Upper Ledger

Yes

6/15/2021

Duplicate

0.14

u

6.2



0.35

J

1.6



0.93

J





























Big Spring 3

No

10/6/2021



0.61



13.3



2.1



99.4



3.7



Evergreen SW

No

DRY NO SAMPLE





















Finch Spring

No

10/5/2021



0.28

J

11.2



0.23

J

50.3



8



Finch Spring

No

10/5/2021

Duplicate

0.29

J

12.1



0.21

J

54



8.8



Formation Spring

Yes

10/5/2021



0.29

J

7.2



0.2

u

1.3



0.56

J

Kelly Pond

No

10/5/2021



0.24

J

16.2



2.5



12.6



2



Lower Ledger

Yes

10/5/2021



0.18

J

6.5



0.2

U

1.4



0.94

J

Spring 2

Yes

10/5/2021



0.17

J

6.6



0.2

U

1.5



1.1



Spring 3

No

10/5/2021



0.16

J

6.3



0.2

U

1.5



0.95

J

Spring 4

Yes

10/5/2021



0.17

J

6.7



0.2

u

1.6



1



Spring A

Yes

10/5/2021



0.22

J

6.7



0.2

U

1.3



1



Spring A

Yes

10/5/2021

Duplicate

0.23

J

6.9



0.2

U

1.3



0.98

J

Upper Ledger

Yes

10/5/2021



0.15

J

7.1



0.2

u

1.6



0.98

J







PSL

50



NA



180



180



260



MCL/RSL

10



40



430



100



86



NOTES: J = estimated concentration
U - not detected
PSL - project screening level

MCL/RSL - EPA primary maximum contaminant level (MCL) for arsenic; or tapwater Regional Screening Level (RSL) for other constituents
Green shading inoicates exceedance of lower criterion (PSL or MCL/RSL)

Yellow shading indicates exceedance of both PSL and MCL/RSL

1-17

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