Eastern_Shawnee_-_TCGW_Apr_2025_Final_-_Copy_0002.pdf

FINAL

GROUNDWATER SAMPLING REPORT

JUNE 2025

TUBA CITY HEADQUARTERS OU-1, OU-2, and OU-3

TUBA CITY, AZ

Prepared For:

Bureau of Indian Affairs Navajo Regional Office

301 W Hill Street Gallup, NM 87301

Prepared by:

Eastern Shawnee Professional Services

6400 Glenwood, Suite 320 Overland Park, KS 66202

PROJECT NO. 1012-01

June 2025

Table of Contents

1 Introduction

1.1 Purpose

2 Background

2.1 Site Description

2.2 Previous Investigations

2.3 Geology

2.4 Hydrogeology

3 Field Work

3.1 Groundwater Sampling

3.2 Inaccessible or Non-Functional Wells

4 Groundwater Sampling Analytical Results

4.1 Analytical Results

4.1.1 Gasoline Range Organics

4.1.2 Diesel Range Organics

4.1.3 Oil Range Organics

4.1.4 Benzene, Toluene, Ethylbenzene and Xylenes (BTEX)

4.1.5 Methyl tert-butyl ether (MTBE)

4.1.6 Polycyclic Aromatic Hydrocarbons (PAHs)

4.2 Field Parameter Measurements

4.3 Analysis Summary

5 Summary 6 Recommendations

Figures

Figure 1 Site Location Figure 2 Well Locations Figure 3 Groundwater Flow Figure 4 Wells Sampled Figure 5 Wells Not Sampled Figure 6 Groundwater Analytical Results – Exceedances

Tables

Table 1 Summary of Analytical Results Table 2 Groundwater Elevation Data

Appendices

Appendix A Pace Analytical Laboratory Report Appendix B Field Forms Appendix C Photo Log

Acronyms and Abbreviations

ADEQ Arizona Department of Environmental Quality AST above ground storage tank BIA Bureau of Indian Affairs bgs below ground surface BTEX benzene, toluene, ethylbenzene and xylenes COC contaminants of concern CSM conceptual site model DPT direct push technologies DRO diesel range organics EPA Environnemental Protection Agency ESPS Eastern Shawnee Professional Services ft feet GRO gasoline range organics LHC liquid-phase hydrocarbons MCL maximum contaminant level ms matrix spike msd matrix spike duplicate MTBE methyl tert-butyl ether NNEPA Navajo Nation Environmental Protection Agency Pace Pace Analytical PAH polycyclic aromatic hydrocarbons PID MiniRAE 2000 photoionization sensor PPE personal protective equipment ORO oil range organics OU operable unit RSL regional screening level TPH total petroleum hydrocarbons Ug/l micrograms per liter USEPA United States Environmental Protection Agency UST underground storage tank VOC volatile organic compounds WP work plan

Final GW Sampling Report – June 2025

Tuba City, Arizona

1 INTRODUCTION

Bureau of Indian Affairs (BIA) Navajo Regional Office (NRO) has contracted Eastern Shawnee Professional Services, LLC (ESPS) to perform Three (3)- Year Groundwater Monitoring in Tuba City, AZ, at three Operation Units (OUs) located around the Tuba City Headquarters. All work was completed under Contract Number 140A0924P0050 and in accordance with the previously approved Work Plan (WP). This Semi-Annual Groundwater Sampling Report details all site activities, work performed, and analytical results of the investigation.

1.1 Purpose

The purpose of this effort was to assess the depth to groundwater and determine the presence or absence of free-phase petroleum hydrocarbons in existing monitoring wells. Additionally, representative groundwater samples were collected from these wells for analysis of petroleum-related hydrocarbons and key natural attenuation monitoring parameters. Following these activities, the intent of the contract effort is to evaluate changes in contaminant plume concentrations at monitoring well locations using historical analytical data and to provide actionable recommendations regarding the necessity of additional remedial actions.

2 BACKGROUND

2.1 Site Description

The Navajo Nation requested continued groundwater monitoring at the Tuba City Headquarters OUs. Tuba City Headquarters is split into three OUs (the site) (Figure 1), the former Tuba City Motors Property (OU-1), the former Heating Plant Property (OU-2), and the Department of Transportation (DOT) Maintenance Yard (OU-3). The site is located in Tuba City, Arizona bordered by Birch Ave to the north, Edgewater Dr. to the south, and with Oak Street and Pine Street bisecting the OUs.

2.2 Previous Investigations

In 1999, a boiler explosion at the plant in OU-2 damaged underground oil supply lines, leading to an unknown quantity of heating oil being released into the subsurface According to a Feasibility Study conducted in 2000 by Geotechnical and Environmental Consultants, Inc.

(GEC), OU-2 formerly utilized heating oil stored in two 50,000-gallon above-ground storage tanks (ASTs). Initial remediation efforts involved the installation of 39 groundwater monitoring wells and 11 extraction wells in the OU-2 area. Subsequent investigations expanded to include OU-1, associated with historical petroleum hydrocarbon releases from a former underground storage tank (UST), and OU-3, due to potential contamination from exterior drum storage and ASTs (GEC, 2000).

In 2018, Envirotech, Inc. was contracted to address petroleum hydrocarbon-contaminated soils in OU-2 and OU-3. Excavation and disposal activities removed approximately 6,440 cubic yards of overburden soil and 2,808 CY of petroleum-contaminated soil from OU-3. Contaminated materials were disposed of at designated facilities. Additionally, a bioremediation injection system was installed in OU-2 and OU-3, with gravel backfill to facilitate future treatment.

Asbestos-containing materials discovered during excavation resulted in temporary work cessation. Despite these measures, residual contamination remained in specific inaccessible areas, as highlighted in a 2019 sampling event (Envirotech, 2018).

At OU-2, approximately 7,000 gallons of liquid-phase hydrocarbons (LHC) and dissolved-phase petroleum products were recovered during remedial actions. A groundwater monitoring report by TerraNext, Inc. in 2011 revealed LHC presence in monitoring well MW-20 and detectable petroleum hydrocarbons in downgradient areas. Site-wide assessments from 2018 suggested multiple petroleum releases had occurred across OU-1, OU-2, and OU-3. Concentrations of benzene, toluene, ethylbenzene, and xylenes (BTEX) slightly exceeded the U.S. Environmental Protection Agency's (EPA) Regional Screening Levels (RSLs) for groundwater ingestion, indicating ongoing contamination (TerraNext, 2011).

Further remediation in 2015-2016 removed approximately 7,500 cubic yards of petroleum-impacted soil from OU-2 and 1,760 CY from OU-1. Excavation reached bedrock interfaces, with backfilling using processed gravel and non-impacted soils. Perforated piping systems were installed to allow for future bioamendment fluid injections. However, residual impacts persisted at the base of the excavation and inaccessible areas, such as beneath utility lines and buildings.

Injection events conducted in 2017 introduced a Custom Blend Nitrate (CBN) fertilizer solution and hydrocarbon-degrading consortia to accelerate bioremediation. These activities were documented in detailed reports by Wells (2017b, 2017d).

Despite significant remediation efforts, contamination remains a concern across the operable units. Persistent petroleum hydrocarbons and localized residual impacts require ongoing monitoring and potential further action. The integration of bioremediation systems and strategic excavation has provided a foundation for addressing subsurface contamination while emphasizing the need for continued site assessment and adaptive remediation strategies to meet EPA standards and protect groundwater resources (Wells, 2017d). All wells previously installed for the monitoring efforts are identified on Figure 2.

2.3 Geology

Tuba City is located on the Colorado Plateau, a geologically diverse region characterized by sedimentary rock formations, mesas, and broad valleys. The area's geology is dominated by sedimentary deposits from the Triassic and Jurassic periods, including the Chinle Formation and the Navajo Sandstone. The Chinle Formation, known for its vibrant red and purple strata, consists primarily of siltstone, mudstone, and sandstone, deposited in fluvial and lacustrine environments approximately 200 million years ago (Blakey & Ranney, 2018). Overlying this is the Navajo Sandstone, a prominent aeolian deposit that forms sweeping cross-bedded structures, indicative of ancient desert dune environments. These layers document the history of dramatic environmental shifts, from wet, riverine systems to arid desert landscapes.

2.4 Hydrogeology

The hydrogeology of Tuba City is influenced by the underlying sedimentary formations, which serve as aquifers and confining layers. The Navajo Sandstone is a significant aquifer, known for its high permeability and capacity to store and transmit groundwater. Below this, the Chinle Formation which often acts as a confining layer due to its lower permeability, particularly in mudstone-dominated intervals (Wilson et al., 1980). Groundwater flow in the region generally follows the topographic gradient, moving from higher elevations toward lower-lying areas.

However, groundwater availability is limited by the arid climate, which results in low recharge rates. Figure 3 shows the groundwater elevation and flow of the site and surrounding area.

Measured groundwater elevation and estimated top of casing elevations based on historical data are identified in Table 2.

3 FIELD WORK

All field activities associated with this groundwater sampling event at the three Tuba City OUs are detailed in the following section. ESPS personnel mobilized to the site on 07 April 2025. All sampling was conducted from April 07 through April 10 . ESPS was provided a list of previously sampled monitoring wells located within the OU footprint by the BIA. During the previous December 2024 sampling event ESPS personnel conducted site reconnaissance to locate all wells and, determine if each well was in good working order and able to be sampled.

All wells that could be located and were sampleable during the December 2024 event were also sampled during this event (Figure 4). Two additional wells were sampled during this sampling event that were not able to be sampled during the previous sampling event. Damaged wells or wells which were not located are shown in Figure 5. Samples were collected from 40 wells. In total 40 parent samples along with associated field quality control (QC) samples, 4 duplicate samples, and 3 matrix spike/matrix spike duplicate (ms/msd) samples, were collected.

Sampling protocol followed standard procedures identified in the Final Work Plan documents.

Sampling Methods

Samples were collected and submitted to Pace Analytical (Pace) for analysis. Pace is located at 12065 Lebanon Road in Mount Juliet, Tennessee. Groundwater samples were analyzed in the laboratory for the following contaminates: GRO, DRO, ORO, BTEX, MTBE, and PAHs.

Laboratory analytical reports can be found in Appendix A of this report.

A summary of groundwater sample analytical results is available in the attached Table 1. All field forms including Field Groundwater Sampling forms, Monitoring Well Inspection forms, Site Safety Tailgate Meeting forms, and calibration forms can be found in Appendix B.

3.1 Groundwater Sampling

Prior to well sampling setup, a MiniRAE 3000 photoionization sensor (PID) was utilized to detect any volatile organic compounds (VOCs). The PID was held into the well casing immediately following the removal of the well cap (if present) to analyze for VOCs emitting from the groundwater. PID readings were recorded on Field Groundwater Sampling Forms. At each well, the depth of groundwater as well as the total depth of the well was measured using a Heron Oil Water Interface Meter prior to sampling, due to known free-product petroleum in wells. The oil water interface meter uses optical refraction and electrical conductance to determine product and water interfaces. A continuous light and tone indicate a non-conductive product (Oil). Water is indicated by intermittent signals. After each well, the probe was decontaminated with Alconox. Depth to water and depth of well data can be found in the attached Table 2.

40 monitoring wells were sampled using a peristaltic pump and in accordance with EPA Low- Flow (Minimal Drawdown) Ground-Water Sampling Procedures. Groundwater was sampled using a peristaltic pump with disposable polyethylene tubing and a flow through cell. Purge water passed through the flow through cell for measurement of groundwater parameters, conductivity, pH, temperature, dissolved oxygen, and oxygen reduction potential, using a YSI

Matrix Number of Samples Collected Analytical Group Analytical Methods

Groundwater

40 parent 4 duplicates Gasoline Range Organics (GRO) 8015D/GRO

40 parent 4 duplicates

Diesel Range Organics (DRO); Oil Range Organics (ORO) 8015D

40 parent 4 duplicates 3 ms/msd

Benzene, Toluene, Ethylbenzene and Xylenes (BTEX);

Methyl tert-butyl ether (MTBE)

8015AZ/8260B

40 parent 4 duplicates

Polycyclic aromatic hydrocarbons (PAHs) 8270C-SIM

556-4 MPS ProDSS-4M Sonde (YSI). Measurements of groundwater parameters were collected every 5 minutes until parameters had stabilized. Groundwater is considered stabilized when pH values are within ±0.1 pH unit, conductivity and temperature readings are within ±10 percent, and dissolved oxygen levels are within ±0.3 milligrams per liter, for 3 consecutive readings.

Parameter readings from the YSI for each 5-minute interval were logged on groundwater sampling forms. Copies of the field sampling forms are included in Appendix B.

Once stabilized, final parameter readings were logged, and groundwater samples were collected in laboratory supplied sample bottles. Samples were collected from the disposable tubing and not from the flow through cell. Samples were labeled and immediately placed on ice in a cooler in preparation for shipping to Pace Analytical located in Mt Juliet, Tennessee. All samples were shipped via priority overnight delivery to Pace.

3.2 Inaccessible or Non-Functional Wells

Twenty-seven wells could not be sampled during this field event. Photos of the wells are included in Appendix C of this report.

• The following wells could not be located: MW-215, MW-216, MW-311, MW-201, MW-

218, , MW-220, MW-222, MW-308, MW-34, MW-212, MW-234, MW-RMF-1, MW-RMF-5

and New Well.

• The following wells were not sampled due to damage to the well: MW-312, MW-20, MW- 24, MW-33, MW-209, MW-210, MW-213, MW-233, MW-236, MW-237, MW-238, and

MW-RMF-2.

• MW-227 could not be sampled due to floating non-aqueous phase liquid (NAPL) in the well.

4 GROUNDWATER SAMPLING ANALYTICAL RESULTS

Analytical groundwater results are compared to Navajo Nation Environmental Protection Agency (NNEPA) Water Cleanup Standards, USEPA MCL for tap water, and ADEQ Tier 1 Water Cleanup Standards. Laboratory analytical results are provided in Table 1 in the Tables section of this report. Figure 6 shows all wells with at least one regulatory limit exceedance.

4.1 Analytical Results

4.1.1 Gasoline Range Organics

GRO analysis was performed on all samples collected from the Tuba City OUs. NNEPA Water Cleanup Standards, USEPA MCL for tap water, and ADEQ Tier 1 Water Cleanup Standards do not have regulatory limits for GRO in groundwater. GRO concentrations range from non-detect to 305 micrograms per liter (ug/L).

4.1.2 Diesel Range Organics

DRO analysis was performed on all samples collected from the Tuba City OUs. NNEPA Water Cleanup Standards, USEPA MCL for tap water, and ADEQ Tier 1 Water Cleanup Standards do not have regulatory limits for DRO in groundwater. DRO concentrations range from non-detect to 6,650 ug/L.

4.1.3 Oil Range Organics

ORO analysis was performed on all samples collected from the Tuba City OUs. NNEPA Water Cleanup Standards, USEPA MCL for tap water, and ADEQ Tier 1 Water Cleanup Standards do not have regulatory limits for ORO in groundwater. ORO concentrations range from non-detect to 1,080 ug/L.

4.1.4 Benzene, Toluene, Ethylbenzene and Xylenes (BTEX)

BTEX analysis was performed on all samples collected from the Tuba City OUs. Analytical results showed zero exceedances for all samples. Benzene, Toluene, and Total Xylenes were not detected in any sample, while Ethylbenzene was detected in 4 of the 40 samples.

Concentrations did not exceed any of the three regulatory limits for the project, with concentrations ranging from 1.21 ug/l to 8.31 ug/l.

4.1.5 Methyl tert-butyl ether (MTBE)

MTBE analysis was performed on all samples collected from the Tuba City OUs. MTBE was detected in 1 of the 40 samples. The concentration of MTBE at MW-1 exceeded the NNEPA Water Cleanup Standard with a concentration of 6.25 ug/L.

4.1.6 Polycyclic Aromatic Hydrocarbons (PAHs)

PAH analysis was performed on all samples collected from the Tuba City OUs.

Benzo(a)anthracene, Benzo(a)pyrene, Benzo(b)fluoranthene, Benzo(g,h,i) perylene, Benzo(k)fluoranthene, Chrysene, Dibenz(a,h)anthracene, Flrouranthene and Indeo(1,2,3-cd)pyrene were not detected in any of the 40 samples.

Concentrations of Anthracene range from non-detect to 0.207 ug/L, with detections in 1 of the 40 samples. No samples exceeded the regulatory limits for this project.

Concentrations of Acenaphthene range from non-detect to 2.14 ug/L, with detections in 11 of the 40 samples. No samples exceeded the regulatory limits for this project.

Concentrations of Acenaphthylene range from non-detect to 0.357 ug/L, with detections in 1 of the 40 samples. No samples exceeded the regulatory limits for this project.

Concentrations of Fluorene range from non-detect to 7.26 ug/L, with detections in 11 of the 40 samples. No samples exceeded the regulatory limits for this project.

Concentrations of Naphthalene range from non-detect to 53.5 ug/L, with detections in 10 of the 40 samples. No samples exceeded the regulatory limits for this project.

Concentrations of Phenanthrene range from non-detect to 5.2 ug/L, with detections in 9 of the 40 samples. Sample exceedances could not be quantified because regularity limits for Phenanthrene are not established for either the NNEPA Water Cleanup Standard, USEPA MCL, or ADEQ Tier 1 Water Cleanup Standard.

Concentrations of Pyrene range from non-detect to 0.748 ug/L, with detections in 10 of the 40 samples. No samples exceeded the regulatory limits for this project.

4.2 Field Parameter Measurements

Field groundwater parameter measurements were collected prior to the collection of each groundwater sample using the flow-through cell and YSI. Groundwater parameters were recorded at the start of water purging and at 5-minute increments prior to sample collection.

Final parameters were recorded immediately before sample collection. Field groundwater parameters are presented in Appendix B on the Groundwater Sampling Forms.

4.3 Analysis Summary

Of the 40 wells sampled, 1 well had a concentration of various analytes that exceeded the regulatory limits, either the NNEPA Water Cleanup Standard, USEPA MCL, or ADEQ Tier 1 Water Cleanup Standard. Samples collected from well MW-1 exceeded regulatory limits for Methyl tert-butyl ether. The sample exceedance occurred from the monitoring well located in OU-2. OU-2 also had the highest concentrations of DRO, and ORO from all samples, the highest concentration of GRO was collected from OU-1. A summary of all the sample with the only concentration that exceeded the regulatory limit is presented in the table below.

Analytical Results Above Regulatory Limits

Groundwater Analytical Results - Exceedances

Sample Area Sample ID

Regulatory Limits

(ug/L) Result (ug/L)

OU-2 TC-MW-1-

04092025 Methyl tert-butyl ether

NNEPA: 2.6

6.25

USEPA MCL: NL

ADEQ Tier 1 Water Cleanup Standards:

NL

Notes:

ADEQ: Arizona Department of Environmental Quality MTBE – Methyl tert-butyl ether NNEPA: Navajo Nation Environmental Protection Agency NL: not listed ug/l – micrograms pers liter USEPA: United States Environmental Protection Agency

5 SUMMARY

ESPS conducted groundwater sampling at three OUs located around the BIA Navajo Nation Tuba City Headquarters. All sampling was conducted from April 7 through April 10 following the procedures outlined in the BIA approved WP. Groundwater samples were collected from 40 wells, along with associated field QC samples.

Groundwater samples were sent to Pace Analytical in Mount Juliet, Tennessee and analyzed in the laboratory for the following contaminates: GRO, DRO, ORO, BTEX, MTBE, and PAHs.

Groundwater stabilization parameters (pH, dissolved oxygen, oxidation reduction potential, and temperature) were recorded at five-minute intervals until the well was within stabilization parameters.

Of the 40 parent samples, 1 sample had an exceedance for 1 analyte: MW-1 exceeded the NNEPA Water Cleanup Standard for MTBE; The sample with a contaminate exceedance was collected from OU-2. Of the three OUs, OU-2 samples had the highest concentration of DRO and ORO. OU-1 had the highest concentration of GRO. NNEPA Water Cleanup Standards, USEPA MCLs, and ADEQ Tier 1 Water Cleanup Standards are not listed for GRO, DRO, or

ORO.

6 RECOMMENDATIONS

ESPS recommends abandoning the damaged wells MW-312, MW-20, MW-24, MW-33, MW- 209, MW-210, MW-213, MW-233, MW-236, MW-237, MW-238, and MW-RMF-2.

Although hydrocarbons do not have MCLs, NNEPA WCS, or an ADEQ Tier 1 contamination levels, hydrocarbons will naturally attenuate into chemicals with known contaminant levels for EPA, NNEPA, and ADEQ. It is evident based on the analytical data and physical observation of

NAPL there is a hydrocarbon plume in the OUs. To further determine the extent and depth of the hydrocarbon plume and understand the characteristics of the lithology and hydrogeology, ESPS recommends a full site characterization using high resolution conceptual site model (CSM) technology. CSM technologies include direct sensing data such as a combination of laser-induced fluorescence; membrane interface probe; and hydraulic profiling tool.

This in-situ data can create 3D models of the subsurface using lithologic data from boring logs along with analytical results from soil and groundwater samples. By synthesizing this information into an interactive database visualization tool, the spatial distribution of contaminants can be clearly displayed within the hydrogeologic framework. This approach provides valuable insights into the interactions between various subsurface media and provides scale-appropriate measurements for the effective management of the contaminated site and assist in determining the best remedial options for the contaminated groundwater.

ESPS recommends using the Ultra Violet Optical Screening Tool (UVOST®) and Frozen Core methods. The UVOST and Frozen Core methods significantly enhance the ability to delineate the extent and depth of hydrocarbon plumes by offering complementary approaches to detect and visualize NAPLs, especially those containing PAHs. UVOST employs laser-induced fluorescence (LIF) technology to detect PAHs in the subsurface by emitting ultraviolet laser pulses that excite PAH molecules, which then fluoresce and emit light of longer wavelengths.

This emitted fluorescence is captured and analyzed to determine the presence, type, and concentration of hydrocarbons. Because this method is highly sensitive to LNAPLs, particularly those present in free-phase or residual saturation, it allows for precise detection even below the water table, bypassing limitations associated with dissolved or vapor phase hydrocarbons.

Moreover, UVOST provides real-time, high-resolution data as it is deployed via direct push drilling methods, allowing for continuous vertical profiling. This real-time data includes waveforms and cluster plots that help distinguish between different types of NAPLs (like gasoline, diesel, or kerosene) and eliminate false positives. This capability is crucial in sites with multiple hydrocarbon sources or where background fluorescence from natural materials could lead to misinterpretation. The ability to rapidly collect dense datasets along vertical transects improves the accuracy of conceptual site models and informs targeted remedial actions. It also facilitates effective lateral and vertical delineation of hydrocarbon impacts, reducing the need for extensive confirmatory soil sampling.

The Frozen Core method complements UVOST by providing visual confirmation and physical evidence of NAPL presence in subsurface soils. By freezing the soil cores, this technique prevents volatilization of hydrocarbons and preserves their in-situ appearance. The cores are then photographed under both white and ultraviolet light in a controlled environment, revealing features that are otherwise difficult to detect, such as light staining or stratified NAPL impacts.

These visual records assist in interpreting UVOST data, selecting accurate subsample locations for laboratory confirmation, and understanding lithological influences on contaminant distribution. The high-resolution photographs also provide a valuable archival reference that supports long-term site monitoring and regulatory documentation.

Together, UVOST and Frozen Core methods offer a robust, integrated approach to characterizing hydrocarbon plumes. While UVOST delivers continuous, quantitative in-situ fluorescence data that distinguishes hydrocarbon types and concentrations with depth, Frozen Core imaging validates these findings with physical samples, enhancing interpretability and confidence. When used in combination, these technologies allow for a clearer, more accurate mapping of hydrocarbon plumes in three dimensions, improving remediation planning, reducing uncertainty, and ultimately accelerating site closure efforts.

References

Blakey, R. C., & Ranney, W. (2018). Ancient Landscapes of the Colorado Plateau. Grand Canyon Association.

Eastern Shawnee Professional Services. (2024). Final Work Plan Three-Year Groundwater Monitoring Tuba City, AZ.

Envirotech, Inc. (2018). Remedial Excavation Report

Geotechnical and Environmental Consultants, Inc. (2000). Feasibility Study Report.

TerraNext, Inc. (2011). Groundwater Monitoring Report.

Wells. (2017b). Bio-injection Program at Operable Units OU-1 and OU-2, Tuba City, Arizona.

Wells. (2017d). Soil Excavation Report.

Wilson, E. D., Moore, R. T., & Cooper, J. R. (1980). Geologic Map of Arizona. Arizona Geological Survey.

Figures

Source: USGS Moenkopi, Tuba City, Moenave, Moenave SE, AZ 7.5 Minute Topo Quad, 1969

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Figure 1

Tuba City Arizona

Site Location Map

Date: 11/6/2024 Drawn By: Susmita Shrestha Project No: 103Z9700

Grand Canyon National Park

Kaibab National Forest

0 1,000 2,000

Feet

Site Location

M a in S t

First Presbyterian

Church

Birch Ave

O a k S t

P in e S t

O a k S t

P in e S t

Dollar General Market

BIA Heating Plant (OU2)

BIA Road Maintenence Facility (OU3)

Tuba City Motor

Company

(OU1)

Source: ESRI, ArcGIS Online, World Imagery, 2021

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Figure 2

Tuba City Arizona

Site Plan Operable Units 1, 2, and 3

Date: 11/6/2024 Drawn By: Susmita Shrestha Project No: 103Z9700

89A

Grand Canyon National Park

Kaibab National Forest

0 100 200

Feet

Legend

Operable Unit (OU) Boundary

BIA Heating Plant (OU2)

BIA Road Maintenence Facility (OU3)

Tuba City Motor

Company

(OU1)

MW-24

NA

MW-33

NA

MW-34

NA

MW-20

NA

MW-218

NA

MW-238

NA

MW-210

NA

MW-212

NA

MW-209

NA

MW-213

NA

MW-237

NA

MW-215

NA

MW-236

NA

MW-234

NA

MW-233

NA

MW-222

NA

MW-227

NA

MW-220

NA

MW-308

NA

MW-201

NA

MW-312

NA

MW-311

NA

MW-216

NA

RMF-MW-2

NA

RMF-MW-5

NA

MW-1

4935.96

MW-8

4932.83

MW-26

4933.54

MW-19

4934.65

MW-15

4936.03

MW-306

4934.8

MW-12

4936.69

MW-32

4939.36

MW-28

4938.56

MW-232

4934.11

MW-231

4936.06

MW-305

4934.29

MW-214

4933.56

MW-235

4934.89

MW-229

Unknown

MW-230

4932.95

MW-228

4934.27

MW-226

4935.02

MW-225

4935.13

MW-208

4935.22

MW-310

4935.37

MW-309

4935.38

MW-204

4936.76

MW-203

4937.25

MW-307

4935.42

MW-223

4935.26

MW-202

4937.11

MW-224

4935.55

MW-205

4938.17

MW-219

4936.59

MW-206

4937.82

MW-207

4937.62

MW-304

4936.49

MW-303

4936.63

MW-302

4936.86

RMF-MW-4

4931.97

RMF-MW-7

4931.56

RMF-MW-1

NA

MW-301

4937.3

MW-211

4933.82

MW-239

4933.52

Approximate Groundwater Flow Direction April 2025

Figure 3

89A

Grand Canyon National Park

0 60 120

Feet

Tuba City Arizona

Date: 5/7/2025 Drawn By: Susmita Shrestha Project No: 103Z9700

Legend

Damaged Wells

NAPL Present

Not Located

Well Sampled

Operable Unit (OU) Boundary

Groundwater Elevation Contour

Approximate Groundwater Flow Direction

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Source: ESRI, ArcGIS Online, World Imagery, 2021

4931.56 Groundwater Elevation in Feet Above

Mean Sea Level

Notes:

The following monitoring wells were not used to generate contours:

MW-8, and RMF-MW-4

Birch Ave a in S t M a in

S t

First Presbyterian

Church

M a in S t

Birch Ave Birch Ave

O a k S t

O a k S t

P in e S t P in e

S t

O a k S t

P in e S tDollar General Market

Birch Ave

S p ru c e S t

BIA Heating Plant (OU2)

BIA Road Maintenence Facility (OU3)

Tuba City Motor

Company

(OU1)

MW-1

MW-8

MW-26MW-19

MW-15

MW-12

MW-32

MW-28

MW-232MW-231

MW-305

MW-211

MW-239

MW-214

MW-306

MW-235

MW-229

MW-230

MW-228

MW-226MW-225MW-208

MW-310

MW-309

MW-204

MW-203 MW-307 MW-223

MW-202 MW-224

MW-205

MW-219

MW-206

MW-207

MW-304

MW-303

MW-302

MW-301

RMF-MW-4

RMF-MW-7

Source: ESRI, ArcGIS Online, World Imagery, 2021

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Figure 4

Tuba City Arizona

Wells Sampled

Date: 4/29/2025 Drawn By: Susmita Shrestha Project No: 103Z9700

89A

Grand Canyon National Park

0 100 200

Feet

Legend

Sampled Wells

Operable Unit (OU) Boundary

Birch Ave a in S t M a in

S t

M a in S t

First Presbyterian

Church

M a in S t

Birch Ave Birch Ave

O a k S t

O a k S t

P in e S t P in e

S t

O a k S t

P in e S tDollar General Market

BIA Heating Plant (OU2)

BIA Road Maintenence Facility (OU3)

Tuba City Motor

Company

(OU1)

MW-24

MW-33

MW-34

MW-20

MW-218

MW-238

MW-210

MW-212MW-209

MW-213

MW-237

MW-215

MW-236

MW-234

MW-233

MW-222

MW-227

MW-220

MW-308

MW-201

MW-312

MW-311

MW-216

RMF-MW-2

RMF-MW-1

RMF-MW-5

Source: ESRI, ArcGIS Online, World Imagery, 2024

X

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\P ro je ct s\ a p rx \T u b a

C ity

.a p rx

Figure 5

Tuba City Arizona

Wells Not Sampled

Date: 4/29/2025 Drawn By: Susmita Shrestha Project No: 103Z9700

89A

Grand Canyon National Park

0 100 200

Feet

Legend

Damaged Wells

NAPL Present

Not Located

Operable Unit (OU) Boundary

89A

Grand Canyon National Park

0 100 200

Feet

BIA Heating Plant (OU2)

BIA Road Maintenence Facility (OU3)

Tuba City Motor

Company

(OU1)

Figure 6

Tuba City Arizona

Groundwater Analytical Results Exceedances

Date: 5/7/2025 Drawn By: Susmita Shrestha Project No: 103Z9700

Legend

Sampled Wells

Estimated Extent of Exceeding Concentrations

Operable Unit (OU) Boundary

MW-26

Notes:

Highlighted indicates concentration exceeding NNEPA standard, US EPA MCL, and/or ADEQ Tier 1 standards Bold cells indicate analyte detected at concentration listed Screening levels calculated using the US EPA Regional Screening Level calculator with a THQ of 1.0 ADEQ: Arizona Department of Environmental Quality D: duplicate sample MCL: maximum concentration limit NL: No Limit ND: Not Detected THQ: Target Health Quotient ug/L: micrograms per liter US EPA: United States Environmental Protection Agency

MW-301

MW-203

MW-228

MW-229

MW-204

C

X \P

\9

\P ro je ct s\ a p rx

\T u b a

C ity .a p rx

Source: ESRI, ArcGIS Online, World Imagery, 2021

MW-28

MW-219

Analyte Result

GRO 279

ORO 173

Acenaphthene 0.104 Fluorene 0.0984

TC-MW-219-04102025

Tables

Table 1 Summary of Analytical Results

G as ol in e R an ge

O rg an ic s (G

R O

D ie se l R an ge

O rg an ic s (D

R O

O il

R an ge O rg an ic s

(O R

O

Be nz en e

To lu en e

Et hy lb en ze ne

To ta l X yl en es

M et hy l t er t-b ut yl e th er

An th ra ce ne

Ac en ap ht he ne

Ac en ap ht hy le ne

Be nz o( a) an th ra ce ne

Be nz o( a) py re ne

Be nz o( b) flu or an th en e

Be nz o( g, h, i)p er yl en e

Be nz o( k) flu or an th en e

C hr ys en e

D ib en z( a, h) an th ra ce ne

Fl ou ra nt he ne

Fl uo re ne

In de o( 1, 2, 3-cd )p yr en e

N ap ht ha le ne

Ph en an th re ne

Py re ne

NL NL NL 5 1000 700 10000 2.6 300 70 NL 0.0012 0.00012 0.0012 NL 0.0038 0.0038 0.005 20 50 0.0012 140 NL 20

NL NL NL 5 1000 700 10000 NL NL NL NL NL 0.2 NL NL NL NL NL NL NL NL NL NL NL

NL NL NL 10 1000 700 10000 NL 2100 420 NL 0.005 0.2 0.0050 NL 0.005 0.005 0.005 280 280 0.05 140 NL 20

Sample Area Sample ID Sample

Date Sample

Type ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L

TC-MW-32-04082025 4/8/2025 N ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND TC-MW-303-04082025 4/8/2025 N 305 166 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND 0.469 ND ND TC-MW-301-04082025 4/8/2025 N ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND

TC-MW-301-04082025-D 4/8/2025 D ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND TC-MW-302-04082025 4/8/2025 N 107 133 ND ND ND 5.14 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND 0.665 ND ND TC-MW-304-04082025 4/8/2025 N ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND

TC-MW-28-040825 4/8/2025 N ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND TC-MW-305-04072025 4/7/2025 N ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND TC-MW-12-04092025 4/9/2025 N ND ND 410 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND TC-MW-207-04092025 4/9/2025 N 172 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND

TC-MW-207-04092025-D 4/9/2025 D 175 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND TC-MW-206-04092025 4/9/2025 N 180 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND TC-MW-205-04092025 4/9/2025 N ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND

TC-MW-8-04092025 4/9/2025 N ND 395 1,030 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND TC-MW-202-04092025 4/9/2025 N ND ND 444 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND

TC-MW-1-04092025 4/9/2025 N ND 3,950 674 ND ND 8.31 ND 6.25 ND 0.382 ND ND ND ND ND ND ND ND ND 0.789 ND 53.5 0.112 ND TC-MW-224-04092025 4/9/2025 N ND 1,700 551 ND ND 1.21 ND ND ND 1.89 0.23 ND ND ND ND ND ND ND ND 3.45 ND 5.03 1.66 0.206 TC-MW-307-04092025 4/9/2025 N 128 6,650 1,080 ND ND ND ND ND ND 2.14 0.357 ND ND ND ND ND ND ND ND 7.26 ND 50.8 5.2 0.656 TC-MW-204-04092025 4/9/2025 N ND ND 288 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND TC-MW-203-04092025 4/9/2025 N ND ND 154 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND

TC-MW-203-04092025-D 4/9/2025 D ND ND 145 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND TC-MW-223-04092025 4/9/2025 N ND 1,520 783 ND ND ND ND ND ND 0.371 ND ND ND ND ND ND ND ND ND 0.776 ND 2.8 1.08 0.153 TC-MW-226-04102025 4/10/2025 N ND ND 188 ND ND ND ND ND ND 0.0583 ND ND ND ND ND ND ND ND ND ND ND ND ND 0.475 TC-MW-225-04102025* 4/10/2025 N ND 1,150 557 ND ND ND ND ND 0.207 1.66 ND ND ND ND ND ND ND ND ND 1.29 ND ND 1.43 0.748 TC-MW-208-04102025 4/10/2025 N ND 756 331 ND ND ND ND ND ND 1.37 ND ND ND ND ND ND ND ND ND 4.49 ND ND 0.961 0.0609 TC-MW-310-04092025 4/9/2025 N ND ND 376 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND 0.066 TC-MW-309-04092025 4/9/2025 N ND 282 614 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND 0.0646 ND 0.352 ND 0.157 TC-MW-229-04102025 4/10/2025 N ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND TC-MW-228-04102025 4/10/2025 N ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND TC-MW-235-04082025 4/8/2025 N ND 468 514 ND ND ND ND ND ND 0.0967 ND ND ND ND ND ND ND ND ND 0.273 ND ND 0.16 ND TC-MW-219-04102025 4/10/2025 N 279 ND 173 ND ND ND ND ND ND 0.104 ND ND ND ND ND ND ND ND ND 0.0984 ND ND ND ND TC-MW-239-04082025 4/8/2025 N ND 1,370 187 ND ND 1.23 ND ND ND 1.080 ND ND ND ND ND ND ND ND ND 1.64 ND 1.820 1.270 ND TC-MW-26-04/07/2025 4/7/2025 N ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND TC-MW-230-04072025 4/7/2025 N ND 245 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND 0.0769

TC-MW-230-04072025-D 4/7/2025 D ND 228 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND 0.103 TC-RWF-MW-7-04072025 4/7/2025 N ND 150 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND

TC-MW-19-04082025 4/8/2025 N ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND TC-MW-232-04082025 4/8/2025 N ND 102 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND TC-MW-231-04082025 4/8/2025 N ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND

TC-RWF-MW-4-04072025 4/7/2025 N ND 145 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND TC-MW-306-04072025 4/7/2025 N ND 124 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND 0.757 ND ND TC-MW-214-04072025 4/7/2025 N ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND TC-MW-211-04072025 4/7/2025 N ND 556 ND ND ND ND ND ND ND 1.26 ND ND ND ND ND ND ND ND ND 1.89 ND 0.629 1.7 ND TC-MW-15-04082025 4/8/2025 N ND 158 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND

Notes:

Highlighted cell indicates concentration exceeding NNEPA standard, US EPA MCL, and/or ADEQ Tier 1 standards Bold cells indicate analyte detected at concentreation listed Screening levels calculated using the US EPA Regional Screening Level calculator with a THQ of 1.0 ADEQ: Arizona Department of Environmental Quality D: duplicate sample MCL: maximum concentration limit N: normal field sample ND: Not Detected THQ: Target Health Quotient ug/L: micrograms per liter US EPA: United States Environmental Protection Agency

* Sample TC-MW-225-041025 was mislabled in the field as MW-222. This sample was collected from MW-225, MW-222 does not exist.

OU-2

OU-3

ADEQ Tier 1 Water Cleanup Standards

Navajo Nation EPA Water Cleanup Standards

Analyte

US EPA MCL

OU-1

SEE NOTES AT END OF TABLE

TABLE 1 : SUMMARY OF GROUNDWATER MONITORING DATA

BUREAU OF INDIAN AFFAIRS OPERABLE UNITS OU-1, OU-2, AND OU-3

Tuba City, Coconino County Arizona

BIA Contract No.140A0924P0050 ESPS Project No.: 1012-01

Well No. Casing Elevation

Well Depth (ft bTOC)

DTW

(12/2024)

WTE

(12/2024)

Well Depth (ft bTOC)

DTW

(04/2025)

WTE

(04/2025)

Well Depth (ft bTOC)

DTW

(x/xxxx)

WTE

(x/xxxx)

Well Depth (ft bTOC)

DTW

(x/xxxx)

WTE

(x/xxxx)

Well Depth (ft bTOC)

DTW

(x/xxxx)

MW-1 4942.82 10.28 8.42 4934.40 9.37 6.86 4935.96

RMF-MW-1b 4941.62 NA NA NA NA NA NA

RMF-MW-2a 4941.62 NA NA NA NA NA NA

RMF-MW-4 4940.31 14.42 9.46 4930.85 14.51 8.34 4931.97

RMF-MW-5b 4942.80 NA NA NA NA NA NA

RMF-MW-7 4941.46 14.04 10.70 4930.76 13.98 9.90 4931.56

MW-8 4939.58 9.32 8.32 4931.26 9.21 6.75 4932.83

MW-12 4943.22 9.89 8.38 4934.84 9.18 6.53 4936.69

MW-15 4944.24 9.96 9.51 4934.73 9.92 8.21 4936.03

MW-19 4943.13 15.17 9.55 4933.58 15.18 8.48 4934.65

MW-20a 4939.40 NA NA NA NA NA NA

MW-24a 4940.43 NA NA NA NA NA NA

MW-26 4943.36 14.83 10.72 4932.64 14.53 9.82 4933.54

MW-28d 4946.67 NA NA NA 9.79 8.11 4938.56

MW-32 4946.75 9.84 8.50 4938.25 9.60 7.39 4939.36

MW-33a 4941.08 NA NA NA NA NA NA

MW-34b 4939.91 NA NA NA NA NA NA

MW-201b 4942.90 NA NA NA NA NA NA

MW-202 4943.16 10.78 7.33 4935.83 10.76 6.05 4937.11

MW-203 4942.15 11.90 6.15 4936.00 11.88 4.90 4937.25

MW-204 4942.30 10.92 6.85 4935.45 10.88 5.54 4936.76

MW-205 4942.63 11.80 6.24 4936.39 11.25 4.46 4938.17

MW-206 4942.18 11.21 6.39 4935.79 11.10 4.36 4937.82

MW-207 4942.82 10.76 6.48 4936.34 10.78 5.20 4937.62

MW-208 4942.55 10.24 8.82 4933.73 10.22 7.33 4935.22

MW-209a 4941.54 NA NA NA NA NA NA

MW-210a 4941.57 NA NA NA NA NA NA

MW-211 4941.38 17.73 8.71 4932.67 17.68 7.56 4933.82

MW-212b 4941.33 NA NA NA NA NA NA

MW-213a 4941.60 NA NA NA NA NA NA

MW-214 4940.49 14.25 8.05 4932.44 14.28 6.93 4933.56

MW-215b 4940.20 NA NA NA NA NA NA

MW-216b 4940.49 NA NA NA NA NA NA

MW-218b 4942.07 NA NA NA NA NA NA

a. Damaged Well

b. Not Located

c. NAPL Present

d. Low Groundwater

e. Well found during most recent event

TABLE 1 : SUMMARY OF GROUNDWATER MONITORING DATA

BUREAU OF INDIAN AFFAIRS OPERABLE UNITS OU-1, OU-2, AND OU-3

Tuba City, Coconino County Arizona

BIA Contract No.140A0924P0050 ESPS Project No.: 1012-01

Well No. Casing Elevation

Well Depth (ft bTOC)

DTW

(12/2024)

WTE

(12/2024)

Well Depth (ft bTOC)

DTW

(04/2025)

WTE

(04/2025)

Well Depth (ft bTOC)

DTW

(x/xxxx)

WTE

(x/xxxx)

Well Depth (ft bTOC)

DTW

(x/xxxx)

WTE

(x/xxxx)

Well Depth (ft bTOC)

DTW

(x/xxxx)

MW-219be 4941.41 NA NA NA 10.71 4.82 4936.59

MW-220b 4939.03 NA NA NA NA NA NA

MW-222b 4938.76 NA NA NA NA NA NA

MW-223 4942.89 11.54 9.70 4933.19 11.54 7.63 4935.26

MW-224 4945.68 15.00 11.50 4934.18 14.99 10.13 4935.55

MW-225 4945.87 14.36 12.37 4933.50 14.33 10.74 4935.13

MW-226 4944.76 17.02 11.02 4933.74 16.99 9.74 4935.02

MW-227c 4944.40 NA NA NA NA NA NA

MW-228 4939.23 11.65 6.06 4933.17 11.59 4.96 4934.27

MW-229 Unknown 7.98 6.62 Unknown 7.78 5.66 Unknown

MW-230 4942.60 14.41 10.20 4932.40 15.33 9.65 4932.95

MW-231 4947.26 20.04 12.43 4934.83 20.12 11.20 4936.06

MW-232 4945.86 18.50 12.35 4933.51 18.47 11.75 4934.11

MW-233a Unknown NA NA NA NA NA NA

MW-234b 4939.49 NA NA NA NA NA NA

MW-235 4940.82 11.48 2.25 4938.57 11.51 5.93 4934.89

MW-236a 4940.76 NA NA NA NA NA NA

MW-237a 4940.38 NA NA NA NA NA NA

MW-238a 4939.85 NA NA NA NA NA NA

MW-239 4941.30 11.61 9.71 4931.59 11.58 7.78 4933.52

MW-301 4945.20 12.53 8.88 4936.32 12.52 7.90 4937.30

MW-302 4943.70 11.95 8.08 4935.62 12.03 6.84 4936.86

MW-303 4945.20 12.43 9.60 4935.60 12.46 8.57 4936.63

MW-304 4942.90 14.73 7.39 4935.51 14.76 6.41 4936.49

MW-305 4942.70 12.80 9.34 4933.36 12.81 8.41 4934.29

MW-306 4941.80 13.98 8.20 4933.60 13.96 7.00 4934.80

MW-307 4941.85 10.21 7.40 4934.45 10.34 6.43 4935.42

MW-308b 4941.90 NA NA NA NA NA NA

MW-309 4941.00 12.20 6.59 4934.41 12.06 5.62 4935.38

MW-310 4940.84 12.97 6.42 4934.42 12.86 5.47 4935.37

MW-311b 4944.82 NA NA NA NA NA NA

MW-312a 4941.47 NA NA NA NA NA NA

NEW WELLb Unknown NA NA NA NA NA NA

a. Damaged Well

b. Not Located

c. NAPL Present

d. Low Groundwater

e. Well found during most recent event

APPENDIX A

Pace Analytical Laboratory

Reports

ANALYTICAL REPORT

Apri l 18 , 2025

Eastern Shawnee Professional Services

Sample Delivery Group: L1845646

Samples Received: 04/09/2025

Project Number:

Description: Tuba City

Report To: Megan Perez-Utter

6400 Glenwood Street

Suite 320

Overland Park, KS 66202

Entire Report Reviewed By:

Apri l 18 , 2025

[Preliminary Report]

Jeff Carr Pro ject Manager

Results relate only to the items tested or calibrated and are reported as rounded values. This test report shall not be reproduced, except in full, without written approval of the laboratory. Where applicable, sampling conducted by Pace Analytical National is performed per guidance provided in laboratory standard operating procedures ENV-SOP-MTJL-0067 and ENV-SOP-MTJL-0068. Where sampling conducted by the customer, results relate to the accuracy of the information provided, and as the samples are received.

Pace Analytical National 12065 Lebanon Rd Mount Ju l ie t , TN 37122 615 -758-5858 800-767-5859 mydata .pace labs .com

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Apri l 18 , 2025

Jeff Carr Pro ject Manager

ACCOUNT: PROJECT: SDG: DATE/TIME: PAGE:

Eastern Shawnee Professional Services L1845646 04/18/25 15:20 1 of 28 https://mydata.pacelabs.com mailto:megan.perezutter@easternshawneecompanies.com?subject=Pace Analytical National SDG: L1845646&body=Email regarding SDG: L1845646 mailto:jeffrey.carr@pacelabs.com?subject=Pace Analytical National SDG: L1845646&body=Email regarding SDG: L1845646 https://mydata.pacelabs.com mailto:jeffrey.carr@pacelabs.com?subject=Pace Analytical National SDG: L1845646&body=Email regarding SDG: L1845646

TABLE OF CONTENTS

Cp: Cover Page 1

Tc: Table of Contents 2

Ss: Sample Summary 3

Cn: Case Narrative 5

Sr: Sample Results 6

TC-RWF-MW-4-040725 L1845646-01 6

TC-MW-305-040725 L1845646-02 7

TC-MW-211-040725 L1845646-03 8

TC-MW-214-040725 L1845646-04 9

TC-MW-306-040725 L1845646-05 10

TC-RWF-7-040725 L1845646-06 11

TC-MW-26-040725 L1845646-07 12

TC-MW-230-040725 L1845646-08 13

TRIP BLANK L1845646-09 14

TC-MW-230-040725-D L1845646-10 15

Qc: Quality Control Summary 16

Volatile Organic Compounds (GC) by Method 8015D/GRO 16

Volatile Organic Compounds (GC/MS) by Method 8260B 18

Semi-Volatile Organic Compounds (GC) by Method 8015D 19

Semi Volatile Organic Compounds (GC/MS) by Method 8270C-SIM 20

Gl: Glossary of Terms 25

Al: Accreditations & Locations 26

Sc: Sample Chain of Custody 27

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SAMPLE SUMMARY

Collected by Collected date/time Received date/time

TC-RWF-MW-4-040725 L1845646-01 GW Summer Manning 04/07/25 10:45 04/09/25 09:00

Method Batch Dilution Preparation Analysis Analyst Location date/time date/time

Volatile Organic Compounds (GC) by Method 8015D/GRO WG2490556 1 04/15/25 00:29 04/15/25 00:29 CDD Mt. Juliet, TN

Volatile Organic Compounds (GC/MS) by Method 8260B WG2488728 1 04/12/25 06:19 04/12/25 06:19 JBE Mt. Juliet, TN

Semi-Volatile Organic Compounds (GC) by Method 8015D WG2488072 1 04/11/25 16:54 04/12/25 05:21 KDB Mt. Juliet, TN

Semi Volatile Organic Compounds (GC/MS) by Method 8270C-SIM WG2487363 1 04/11/25 06:53 04/11/25 21:11 VDR Mt. Juliet, TN

Collected by Collected date/time Received date/time

TC-MW-305-040725 L1845646-02 GW Summer Manning 04/07/25 12:05 04/09/25 09:00

Method Batch Dilution Preparation Analysis Analyst Location date/time date/time

Volatile Organic Compounds (GC) by Method 8015D/GRO WG2490556 1 04/15/25 01:02 04/15/25 01:02 CDD Mt. Juliet, TN

Volatile Organic Compounds (GC/MS) by Method 8260B WG2488728 1 04/12/25 06:40 04/12/25 06:40 JBE Mt. Juliet, TN

Semi-Volatile Organic Compounds (GC) by Method 8015D WG2488072 1 04/11/25 16:54 04/12/25 05:41 KDB Mt. Juliet, TN

Semi Volatile Organic Compounds (GC/MS) by Method 8270C-SIM WG2487363 1 04/11/25 06:53 04/11/25 21:30 VDR Mt. Juliet, TN

Collected by Collected date/time Received date/time

TC-MW-211-040725 L1845646-03 GW Summer Manning 04/07/25 13:00 04/09/25 09:00

Method Batch Dilution Preparation Analysis Analyst Location date/time date/time

Volatile Organic Compounds (GC) by Method 8015D/GRO WG2490556 1 04/15/25 01:25 04/15/25 01:25 CDD Mt. Juliet, TN

Volatile Organic Compounds (GC/MS) by Method 8260B WG2488728 1 04/12/25 07:02 04/12/25 07:02 JBE Mt. Juliet, TN

Semi-Volatile Organic Compounds (GC) by Method 8015D WG2488072 1 04/11/25 16:54 04/12/25 06:01 KDB Mt. Juliet, TN

Semi Volatile Organic Compounds (GC/MS) by Method 8270C-SIM WG2487363 1 04/11/25 06:53 04/11/25 21:50 VDR Mt. Juliet, TN

Collected by Collected date/time Received date/time

TC-MW-214-040725 L1845646-04 GW Summer Manning 04/07/25 14:00 04/09/25 09:00

Method Batch Dilution Preparation Analysis Analyst Location date/time date/time

Volatile Organic Compounds (GC) by Method 8015D/GRO WG2490556 1 04/15/25 01:48 04/15/25 01:48 CDD Mt. Juliet, TN

Volatile Organic Compounds (GC/MS) by Method 8260B WG2488728 1 04/12/25 07:23 04/12/25 07:23 JBE Mt. Juliet, TN

Semi-Volatile Organic Compounds (GC) by Method 8015D WG2488072 1 04/11/25 16:54 04/12/25 06:22 KDB Mt. Juliet, TN

Semi Volatile Organic Compounds (GC/MS) by Method 8270C-SIM WG2487363 1 04/11/25 06:53 04/11/25 22:09 VDR Mt. Juliet, TN

Collected by Collected date/time Received date/time

TC-MW-306-040725 L1845646-05 GW Summer Manning 04/07/25 14:43 04/09/25 09:00

Method Batch Dilution Preparation Analysis Analyst Location date/time date/time

Volatile Organic Compounds (GC) by Method 8015D/GRO WG2490556 1 04/15/25 02:11 04/15/25 02:11 CDD Mt. Juliet, TN

Volatile Organic Compounds (GC/MS) by Method 8260B WG2488728 1 04/12/25 07:44 04/12/25 07:44 JBE Mt. Juliet, TN

Semi-Volatile Organic Compounds (GC) by Method 8015D WG2488072 1 04/11/25 16:54 04/12/25 06:42 KDB Mt. Juliet, TN

Semi Volatile Organic Compounds (GC/MS) by Method 8270C-SIM WG2487364 1 04/11/25 07:35 04/12/25 00:11 ALM Mt. Juliet, TN

Collected by Collected date/time Received date/time

TC-RWF-7-040725 L1845646-06 GW Summer Manning 04/07/25 16:10 04/09/25 09:00

Method Batch Dilution Preparation Analysis Analyst Location date/time date/time

Volatile Organic Compounds (GC) by Method 8015D/GRO WG2492082 1 04/17/25 11:06 04/17/25 11:06 DWR Mt. Juliet, TN

Volatile Organic Compounds (GC/MS) by Method 8260B WG2488728 1 04/12/25 08:06 04/12/25 08:06 JBE Mt. Juliet, TN

Semi-Volatile Organic Compounds (GC) by Method 8015D WG2488072 1 04/11/25 16:54 04/12/25 01:40 KDB Mt. Juliet, TN

Semi Volatile Organic Compounds (GC/MS) by Method 8270C-SIM WG2487364 1 04/11/25 07:35 04/11/25 17:39 JDJ Mt. Juliet, TN

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SAMPLE SUMMARY

Collected by Collected date/time Received date/time

TC-MW-26-040725 L1845646-07 GW Summer Manning 04/07/25 17:05 04/09/25 09:00

Method Batch Dilution Preparation Analysis Analyst Location date/time date/time

Volatile Organic Compounds (GC) by Method 8015D/GRO WG2490556 1 04/15/25 02:57 04/15/25 02:57 CDD Mt. Juliet, TN

Volatile Organic Compounds (GC/MS) by Method 8260B WG2488728 1 04/12/25 08:27 04/12/25 08:27 JBE Mt. Juliet, TN

Semi-Volatile Organic Compounds (GC) by Method 8015D WG2488072 1 04/11/25 16:54 04/12/25 07:02 KDB Mt. Juliet, TN

Semi Volatile Organic Compounds (GC/MS) by Method 8270C-SIM WG2487364 1 04/11/25 07:35 04/12/25 00:31 ALM Mt. Juliet, TN

Collected by Collected date/time Received date/time

TC-MW-230-040725 L1845646-08 GW Summer Manning 04/07/25 17:54 04/09/25 09:00

Method Batch Dilution Preparation Analysis Analyst Location date/time date/time

Volatile Organic Compounds (GC) by Method 8015D/GRO WG2490556 1 04/15/25 03:21 04/15/25 03:21 CDD Mt. Juliet, TN

Volatile Organic Compounds (GC/MS) by Method 8260B WG2488728 1 04/12/25 08:49 04/12/25 08:49 JBE Mt. Juliet, TN

Semi-Volatile Organic Compounds (GC) by Method 8015D WG2488072 1 04/11/25 16:54 04/12/25 07:22 KDB Mt. Juliet, TN

Semi Volatile Organic Compounds (GC/MS) by Method 8270C-SIM WG2487364 1 04/11/25 07:35 04/12/25 00:51 ALM Mt. Juliet, TN

Collected by Collected date/time Received date/time

TRIP BLANK L1845646-09 GW Summer Manning 04/08/25 08:00 04/09/25 09:00

Method Batch Dilution Preparation Analysis Analyst Location date/time date/time

Volatile Organic Compounds (GC/MS) by Method 8260B WG2488728 1 04/12/25 05:57 04/12/25 05:57 JBE Mt. Juliet, TN

Collected by Collected date/time Received date/time

TC-MW-230-040725-D L1845646-10 GW Summer Manning 04/07/25 17:54 04/09/25 09:00

Method Batch Dilution Preparation Analysis Analyst…