FINAL

Site Inspection Report 

Camp Navajo,

Bellemont, Arizona

Site Inspection for Perfluorooctanoic acid (PFOA), 

Perfluorooctanesulfonic acid (PFOS), Perfluorohexanesulfonic 

acid (PFHxS), Perfluorononanoic acid (PFNA), 

Hexafluoropropylene oxide dimer acid (HFPO-DA), and 

Perfluorobutanesulfonic acid (PFBS) at ARNG Installations, 

Nationwide

June 2023

Prepared for:

Army National Guard Bureau

111 S. George Mason Drive

Arlington, VA 22204

UNCLASSIFIED
 

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Table of Contents

Executive Summary ..............................................................................................................ES-1

1. Introduction ..................................................................................................................1-1

1.1 Project Authorization .............................................................................................1-1

1.2 SI Purpose ............................................................................................................1-1

2. Facility Background ......................................................................................................2-1

2.1 Facility Location and Description...........................................................................2-1

2.2 Facility Environmental Setting ...............................................................................2-1

2.2.1 Geology ......................................................................................................2-2

2.2.2 Hydrogeology..............................................................................................2-2

2.2.3 Hydrology....................................................................................................2-3

2.2.4 Climate........................................................................................................2-3

2.2.5 Current and Future Land Use......................................................................2-3

2.2.6 Sensitive Habitat and Threatened/ Endangered Species.............................2-4

2.3 History of PFAS Use..............................................................................................2-4

2.4 Other PFAS Investigations ....................................................................................2-5

3. Summary of Areas of Interest .......................................................................................3-1

3.1 AOI 1 Former Building 209....................................................................................3-1

3.2 AOI 2 Former Building LR200 ...............................................................................3-1

3.3 AOI 3 Building 2 ....................................................................................................3-1

3.4 AOI 4 WWTP Holding Ponds and Effluent Reuse Site...........................................3-2

3.5 AOI 5 NAAD-40.....................................................................................................3-2

3.6 AOI 6 North and South Holding Ponds ..................................................................3-2

4. Project Data Quality Objectives ....................................................................................4-1

4.1 Problem Statement ...............................................................................................4-1

4.2 Information Inputs .................................................................................................4-1

4.3 Study Boundaries..................................................................................................4-1

4.4 Analytical Approach...............................................................................................4-1

4.5 Data Usability Assessment....................................................................................4-2

5. Site Inspection Activities ...............................................................................................5-1

5.1 Pre-Investigation Activities.....................................................................................5-1

5.1.1 Technical Project Planning ..........................................................................5-1

5.1.2 Utility Clearance..........................................................................................5-2

5.1.3 Source Water and Sampling Equipment Acceptability .................................5-2

5.2 Soil Borings and Soil Sampling .............................................................................5-2

5.3 Groundwater Grab Sampling.................................................................................5-3

5.4 Spring Sampling....................................................................................................5-4

5.5 Surface Water and Sediment Sampling.................................................................5-4

5.6 Water Level Measurements...................................................................................5-5

5.7 Investigation-Derived Waste..................................................................................5-5

5.8 Laboratory Analytical Methods ..............................................................................5-5

5.9 Deviations from SI QAPP Addendum ....................................................................5-6

6. Site Inspection Results .................................................................................................6-1

6.1 Screening Levels...................................................................................................6-1

6.2 Soil Physicochemical Analyses .............................................................................6-2
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6.3 AOI 1.....................................................................................................................6-2

6.3.1 AOI 1 Soil Analytical Results .......................................................................6-2

6.3.2 AOI 1 Groundwater Analytical Results.........................................................6-2

6.3.3 AOI 1 Conclusions ......................................................................................6-3

6.4 AOI 2.....................................................................................................................6-3

6.4.1 AOI 2 Soil Analytical Results .......................................................................6-3

6.4.2 AOI 2 Conclusions ......................................................................................6-3

6.5 AOI 3.....................................................................................................................6-3

6.5.1 AOI 3 Soil Analytical Results .......................................................................6-3

6.5.2 AOI 3 Groundwater Analytical Results.........................................................6-4

6.5.3 AOI 3 Conclusions ......................................................................................6-4

6.6 AOI 4.....................................................................................................................6-4

6.6.1 AOI 4 Soil Analytical Results .......................................................................6-4

6.6.2 AOI 4 Conclusions ......................................................................................6-4

6.7 AOI 5.....................................................................................................................6-4

6.7.1 AOI 5 Groundwater Analytical Results.........................................................6-5

6.7.2 AOI 5 Conclusions ......................................................................................6-5

6.8 AOI 6.....................................................................................................................6-5

6.8.1 AOI 6 Soil Analytical Results .......................................................................6-5

6.8.2 AOI 6 Groundwater Analytical Results.........................................................6-6

6.8.3 AOI 6 Conclusions ......................................................................................6-6

6.9 Atherton Lake........................................................................................................6-6

6.9.1 Atherton Lake Surface Water Analytical Results..........................................6-6

6.9.2 Atherton Lake Sediment Analytical Results .................................................6-6

6.9.3 Atherton Lake Conclusions .........................................................................6-6

7. Exposure Pathways......................................................................................................7-1

7.1 Soil Exposure Pathway .........................................................................................7-1

7.1.1 AOI 1...........................................................................................................7-1

7.1.2 AOI 2...........................................................................................................7-2

7.1.3 AOI 3...........................................................................................................7-2

7.1.4 AOI 4...........................................................................................................7-2

7.1.5 AOI 5...........................................................................................................7-2

7.1.6 AOI 6...........................................................................................................7-3

7.2 Groundwater Exposure Pathway...........................................................................7-3

7.2.1 AOI 1, AOI 3, and AOI 6 ..............................................................................7-3

7.2.2 AOI 2 and 4.................................................................................................7-3

7.2.3 AOI 5...........................................................................................................7-3

7.3 Surface Water and Sediment Exposure Pathway ..................................................7-4

7.3.1 AOI 1...........................................................................................................7-4

7.3.2 AOI 2...........................................................................................................7-4

7.3.3 AOI 3...........................................................................................................7-4

7.3.4 AOI 4...........................................................................................................7-5

7.3.5 AOI 5...........................................................................................................7-5

7.3.6 AOI 6...........................................................................................................7-5

8. Summary and Outcome................................................................................................8-1

8.1 SI Activities............................................................................................................8-1
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8.2 Outcome ...............................................................................................................8-1

9. References...................................................................................................................9-1
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Appendices

Appendix A Data Usability Assessment and Validation Reports

Appendix B Field Documentation

B1. Log of Daily Notice of Field Activities

B2. Sampling Forms

B3. Field Change Request Forms

B4. Nonconformance and Corrective Action Reports

B5. Investigation-Derived Waste Polygons

Appendix C Photographic Log

Appendix D TPP Meeting Minutes

Appendix E Boring Logs

Appendix F Analytical Results

Appendix G Laboratory Reports

Figures

Figure 2-1 Facility Location

Figure 2-2 Facility Topography

Figure 2-3 Groundwater Features

Figure 2-4 Well Network

Figure 2-5 Surface Water Features

Figure 3-1 Areas of Interest

Figure 5-1 Site Inspection Sample Locations

Figure 5-2 Site Inspection Sample Locations – AOI 1, AOI 3, AOI 6

Figure 5-2A Site Inspection Sample Locations – AOI 1, AOI 3, AOI 6 Zoom

Figure 5-3 Site Inspection Sample Locations – AOI 2 and AOI 4

Figure 5-4 Site Inspection Sample Locations – AOI 5

Figure 6-1 PFOA Detections in Soil - AOI 1, AOI 3, AOI 6

Figure 6-2 PFOA Detections in Soil - AOI 2 and AOI 4

Figure 6-3 PFOS Detections in Soil - AOI 1, AOI 3, AOI 6

Figure 6-4 PFOS Detections in Soil - AOI 2 and AOI 4

Figure 6-5 PFBS Detections in Soil – AOI 1, AOI 3, AOI 6

Figure 6-6 PFBS Detections in Soil – AOI 2 and AOI 4

Figure 6-7 PFHxS Detections in Soil – AOI 1, AOI 3, AOI 6

Figure 6-8 PFHxS Detections in Soil – AOI 2 and AOI 4

Figure 6-9 PFNA Detections in Soil – AOI 1, AOI 3, AOI 6

Figure 6-10 PFNA Detections in Soil – AOI 2 and AOI 4

Figure 6-11 PFOA, PFOS, and PFBS Detections in Groundwater

Figure 6-12 PFHxS and PFNA Detections in Groundwater

Figure 6-13 PFOA, PFOS, and PFBS Detections in Surface Water

Figure 6-14 PFHxS and PFNA Detections in Surface Water

Figure 6-15 PFOA, PFOS, and PFBS Detections in Sediment

Figure 6-16 PFHxS and PFNA Detections in Sediment

Figure 7-1 Conceptual Site Model, AOI 1

Figure 7-2 Conceptual Site Model, AOI 2

Figure 7-3 Conceptual Site Model, AOI 3

Figure 7-4 Conceptual Site Model, AOI 4

Figure 7-5 Conceptual Site Model, AOI 5

Figure 7-6 Conceptual Site Model, AOI 6
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Tables

Table ES-1 Screening Levels (Soil and Groundwater)

Table ES-2 Summary of Site Inspection Findings and Recommendations

Table 2-1 July 2022 PFOA, PFOS, PFHxS, PFNA, and PFBS Sampling Results

Table 5-1 Site Inspection Samples by Medium

Table 5-2 Soil Boring Depths, Well Screen Intervals, and Groundwater Elevations

Table 6-1 Screening Levels (Soil and Groundwater)

Table 6-2 PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Surface Soil

Table 6-3 PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Shallow Subsurface Soil

Table 6-4 PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Deep Subsurface Soil

Table 6-5 PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Groundwater

Table 6-6 PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Sediment

Table 6-7 PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Surface Water

Table 8-1 Summary of Site Inspection Findings and Recommendations
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Acronyms and Abbreviations

% percent

°C degrees Celsius

°F degrees Fahrenheit

μg/kg micrograms per kilogram

ADEQ Arizona Department of Environmental Quality

ADWR Arizona Department of Water Resources

AECOM AECOM Technical Services, Inc.

AFFF aqueous film-forming foam

AOI Area of Interest

ARNG Army National Guard

AZARNG Arizona Army National Guard

AZDEMA Arizona Department of Emergency and Military Affairs

bgs below ground surface 

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act 

CoC chain of custody

CSM conceptual site model 

DA Department of the Army

DESCOM Army Depot System Command

DoD Department of Defense

DO dissolved oxygen

DQO data quality objective

DUA data usability assessment

ELAP Environmental Laboratory Accreditation Program

EM Engineer Manual

ERB equipment rinsate blank

FedEx Federal Express

gpd gallons per day

gpm gallons per minute

HDPE high-density polyethylene 

HFPO-DA hexafluoropropylene oxide dimer acid

HSA hollow stem auger 

IDW investigation-derived waste

ITRC Interstate Technology Regulatory Council

LC/MS/MS liquid chromatography with tandem mass spectrometry

MIL-SPEC military specification

NADA Navajo Army Depot

NELAP National Environmental Laboratory Accreditation Program

ng/L nanograms per liter

NOD Navajo Ordnance Depot

ORP oxidation-reduction potential

OSD Office of the Secretary of Defense

PA Preliminary Assessment

PFAS per- and polyfluoroalkyl substances
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PFBS perfluorobutanesulfonic acid

PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

PID photoionization detector

PQAPP Programmatic UFP-QAPP

QA quality assurance 

QAPP Quality Assurance Project Plan

QC quality control

QSM Quality Systems Manual

RI Remedial Investigation

SI Site Inspection

SL screening level

TOC total organic carbon

TPP Technical Project Planning

UFP Uniform Federal Policy

US United States

USACE United States Army Corps of Engineers

USCS Unified Soil Classification System

USEPA United States Environmental Protection Agency

USFWS United States Fish and Wildlife Service 

WWTP wastewater treatment plant
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Executive Summary

The Army National Guard (ARNG) G-9 is performing Preliminary Assessments (PAs) and Site 

Inspections (SIs) on the current or potential historical use of per- and polyfluoroalkyl substances 

(PFAS) with a focus on the six compounds presented in the memorandum from the Office of the 

Secretary of Defense (OSD) dated 6 July 2022 (Assistant Secretary of Defense, 2022). The six 

compounds listed in the OSD memorandum include perfluorooctanesulfonic acid (PFOS), 

perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorohexanesulfonic acid 

(PFHxS), hexafluoropropylene oxide dimer acid (HFPO-DA)1

, and perfluorobutanesulfonic acid 

(PFBS). These compounds are collectively referred to as “relevant compounds” throughout the 

document and the applicable screening levels (SLs) are provided in Table ES-1. 

The PA identified six Areas of Interest (AOIs) where PFAS-containing materials may have been 

used, stored, disposed, or released historically (see Table ES-2 for AOI locations). The objective 

of the SI is to identify whether there has been a release to the environment from the AOIs identified 

in the PA and determine whether further investigation is warranted, a removal action is required 

to address immediate threats, or no further action is required based on screening levels (SLs) for 

relevant compounds. This SI was completed at Camp Navajo in Bellemont Arizona and 

determined further evaluation under the Comprehensive Environmental Response, 

Compensation, and Liability Act (CERCLA) is warranted for AOI 1, AOI 3, AOI 5, and AOI 6; no 

further evaluation is warranted at AOI 2 and AOI 4 at this time. Camp Navajo will also be referred 

to as the “facility” throughout this document. 

Camp Navajo is located in north-central Arizona, 12 miles west of Flagstaff, 17 miles east of 

Williams, and adjacent to the industrial community of Bellemont. The facility comprises 28,473 

acres along Interstate 40. The installation comprises 28,473 acres and is used to support the 

installation’s munitions storage mission and support of various training missions (Arizona ARNG

[AZARNG], 2020).

The PA identified six AOIs for investigation during the SI phase. SI sampling results from the six

AOIs were compared to OSD SLs. Table ES-2 summarizes the SI results for each AOI. Based on 

the results of this SI, further evaluation under CERCLA is warranted in a Remedial Investigation

(RI) for AOI 1, AOI 3, AOI 5, and AOI 6; no further evaluation is warranted at AOI 2 and AOI 4 at 

this time. 

1 Of the six PFAS compounds presented in the 6 July 2022 OSD memorandum, HFPO-DA (commonly referred to as GenX) was not 

included as an analyte at the time of this SI. Based on the conceptual site model (CSM) developed during the PA and revised based 

on SI findings, the presence of HFPO-DA is not anticipated at the facility because HFPO-DA is generally not a component of military 

specification (MIL-SPEC) aqueous film forming foam (AFFF) and based on its history including distribution limitations that restricted 

use of GenX, it is generally not a component of other products the military used. In addition, it is unlikely that GenX would be an 

individual chemical of concern in the absence of other PFAS. 
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Table ES-1: Screening Levels (Soil and Groundwater) 

Analyteb

Residential

(Soil)

(μg/kg)a 

0-2 feet bgs

Industrial/ Commercial 

Composite Worker

(Soil)

(μg/kg)a 

2-15 feet bgs

Tap Water

(Groundwater)

(ng/L)a

PFOA 19 250 6

PFOS 13 160 4 

PFBS 1,900 25,000 601 

PFHxS 130 1,600 39

PFNA 19 250 6

Notes:

bgs = below ground surface; μg/kg = micrograms per kilogram; ng/L = nanograms per liter

a.) Assistant Secretary of Defense, 2022. Risk Based Screening Levels in Groundwater and Soil using United States Environmental Protection 

Agency’s (USEPA’s) Regional Screening Level Calculator. Hazard Quotient (HQ) = 0.1. 6 July 2022. 

b.) Of the six PFAS compounds presented in the 6 July 2022 OSD memorandum, HFPO-DA (commonly referred to as GenX) was not included 

as an analyte at the time of this SI. Based on the CSM developed during the PA and revised based on SI findings, the presence of HFPODA is not anticipated at the facility because HFPO-DA is generally not a component of MIL-SPEC AFFF and based on its history including 

distribution limitations that restricted use of GenX, it is generally not a component of other products the military used. In addition, it is 

unlikely that GenX would be an individual chemical of concern in the absence of other PFAS. 

Table ES-2: Summary of Site Inspection Findings and Recommendations

AOI Potential 

Release Area

Soil –

Source Area

Groundwater –

Source Area Future Action

1 Former Building 

209 Proceed to RI 

2 Former Building 

LR200 N/A No further 

action

3 Building 2 Proceed to RI

4 

WWTP Holding 

Ponds and 

Effluent Reuse 

Site

N/A No further 

action

5 NAAD-40 N/A Proceed to RI

6 North and South 

Holding Ponds Proceed to RI

Legend:

N/A = not applicable 

= detected; exceedance of the screening levels

= detected; no exceedance of the screening levels

= not detected
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1. Introduction

1.1 Project Authorization

The Army National Guard (ARNG) G-9 is the lead agency in performing Preliminary Assessments 

(PAs) and Site Inspections (SIs) on the current or potential historical use of per- and 

polyfluoroalkyl substances (PFAS) with a focus on the six compounds presented in the 

memorandum from the Office of the Secretary of Defense (OSD) dated 6 July 2022 (Assistant 

Secretary of Defense, 2022). The six compounds listed in the OSD memorandum will be referred 

to as “relevant compounds” throughout this document and include perfluorooctanoic acid (PFOA), 

perfluorooctanesulfonic acid (PFOS), perfluorohexanesulfonic acid (PFHxS), perfluorononanoic 

acid (PFNA), hexafluoropropylene oxide dimer acid (HFPO-DA)1

, and perfluorobutanesulfonic 

acid (PFBS) at ARNG facilities nationwide. The ARNG performed this SI at Camp Navajo in 

Bellemont, Arizona. Camp Navajo is also referred to as the “facility” throughout this document. 

The SI project elements were performed in compliance with Comprehensive Environmental 

Response, Compensation, and Liability Act (CERCLA; United States [US] Environmental 

Protection Agency [USEPA], 1980), as amended, the National Oil and Hazardous Substances 

Pollution Contingency Plan (40 Code of Federal Regulations Part 300; USEPA, 1994), and in 

compliance with US Department of the Army (DA) requirements and guidance for field 

investigations. 

1.2 SI Purpose

A PA was performed at Camp Navajo (AECOM Technical Services, Inc. [AECOM], 2020) that

identified six Areas of Interest (AOIs) where PFAS-containing materials may have been used, 

stored, disposed, or released historically. The objective of the SI is to identify whether there has 

been a release to the environment from the AOIs identified in the PA and determine whether 

further investigation is warranted, a removal action is required to address immediate threats, or 

no further action is required based on screening levels (SLs) for the relevant compounds. 

1 Of the six PFAS compounds presented in the 6 July 2022 OSD memorandum, HFPO-DA (commonly referred to as GenX) was not 

included as an analyte at the time of this SI. Based on the conceptual site model (CSM) developed during the PA and revised based 

on SI findings, the presence of HFPO-DA is not anticipated at the facility because HFPO-DA is generally not a component of military 

specification (MIL-SPEC) aqueous film forming foam (AFFF) and based on its history including distribution limitations that restricted 

use of GenX, it is generally not a component of other products the military used. In addition, it is unlikely that GenX would be an 

individual chemical of concern in the absence of other PFAS. 
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2. Facility Background 

2.1 Facility Location and Description

Camp Navajo is located in north-central Arizona, 12 miles west of Flagstaff, 17 miles east of 

Williams, and adjacent to the industrial community of Bellemont located along Interstate 40 

(Figure 2-1). The facility is located in a topographic basin of the San Francisco Plateau within 

south-central Coconino County, between the Coconino and Kaibab National Forests. The 

installation comprises 28,473 acres and is used to support the installation’s munitions storage 

mission and support of various training missions (Arizona ARNG [AZARNG], 2020).

Prior to military use, the land currently occupied by Camp Navajo was used for homesteading, 

ranching, and logging. Lands for the installation were purchased from private landowners and 

lands that were transferred from the Kaibab and Coconino National Forests. These lands were 

combined to form the Navajo Ordnance Depot (NOD) in 1942. Initial construction at the facility

was completed in 1943 (AZARNG, 2020).

In 1945, NOD’s mission was expanded to include a prisoner-of-war camp that continued until the 

end of World War II. Storage of chemical warfare service ammunition, explosives, and other 

ammunition continued throughout this time. In 1967, the NOD was designated a Defense Supply 

Agency Depot; in 1971, it was renamed the Navajo Army Depot Activity (NADA) and placed under 

the command of the Pueblo Army Depot. In 1982, the AZARNG assumed operational control of 

NADA and performed the Army Depot System Command’s (DESCOM) mission of receipt, 

storage, shipping, maintenance, and disposal of munitions to enhance the training of AZARNG 

units. In 1988, NADA was closed as a federally funded and controlled installation under the Base 

Realignment and Closure Act but continued through 1992 to store ammunition using funding 

provided by DESCOM, while the AZARNG used the installation as a training facility. In 1993, the 

installation was renamed Camp Navajo (AZARNG, 2020). 

2.2 Facility Environmental Setting

The facility is located near the southern edge of the Colorado Plateau physiographic province, at 

an elevation of approximately 7,050 feet (Figure 2-2). The southern Colorado Plateau is elevated 

relative to surrounding areas. The plateau surface regionally slopes gently upward to the 

southwest, reflecting the general dip of the carbonate strata. Twelve (12) miles south of 

Bellemont, the plateau abruptly ends at the Mogollon Rim, a steep south-facing escarpment with 

up to 2,500 feet of relief (Wilkinson, 2000).

Bellemont lies within the northernmost extent of the Verde River watershed, which drains a portion 

of central Arizona. The Verde River lies below the Mogollon Rim in the Verde Valley; it is fed by 

tributaries whose canyons deeply incise the Rim and whose sub-watersheds extend up on to the 

plateau. Oak Creek, West Fork, and Sycamore Canyons reach to within a few miles of the 

southern boundary of Camp Navajo. Perennial springs in the canyon bottoms drain the plateau 

subsurface, resulting in water levels as deep as 1,500 feet to 1,700 feet in the regional aquifers. 

The upper portions of the sub-watersheds are ephemeral and only flow in response to significant 

storm or snowmelt events (Wilkinson, 2000).

The seeps and springs in the town of Bellemont issue from volcanic rocks, and the majority of 

them occur at the lithologic contact between the Wild Bill Hill basalt flow and the underlying Camp 

Navajo clay. Most springs are ephemeral, but a few are perennial during most years (Wilkinson, 

2000). The springs and karst in the Bellemont area indicate a significant amount of precipitation 

infiltrates into the subsurface. The majority of terrain consists of permeable cinders, lava, and 

carbonate rocks, with only a thin residuum of unconsolidated sediments and poorly developed 

soil. However, only a small portion of the volcanic terrain has associated springs. No springs issue 
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from the carbonate rocks, which suggests that a significant amount of the infiltrate percolates 

downward to recharge the regional aquifers. 

2.2.1 Geology

Camp Navajo is located along the southern edge of the Colorado Plateau, where volcanic units 

of the San Francisco volcanic field sit above sedimentary rock units of Paleozoic, Mesozoic, and 

Tertiary age. The Colorado Plateau is bordered by the Transition Zone to the south and is

separated by the physiographic boundary of the Mogollon Rim approximately 6 miles to the south 

of Camp Navajo. Multiple volcanic features are present in, and around, Camp Navajo. The 

majority of igneous units at Camp Navajo are basaltic flows that originated from the numerous 

vents distributed over most of the installation (Weston, 2018a). 

A unit consisting of predominantly silt and clay with distinct sand layers has been mapped in the 

northern and central portions of Camp Navajo and is informally known as the Camp Navajo Clay. 

Individual sand layers are present to a depth of approximately 20 feet below ground surface (bgs). 

The sand units are thin and yield limited amounts of water. Variable amounts of gravel or artificial 

material are present at the surface and shallow depths due to backfill and construction activities 

during the development of Camp Navajo. The Camp Navajo Clay extends to an approximate 

depth of 55 feet bgs and is underlain by gravel deposits and basalt flows (Weston, 2018a). In the 

northwestern side of Camp Navajo, Pleistocene basalt overlays the clay layer, creating natural 

springs further discussed in Section 2.2.2. 

Structurally, the northeasterly-striking Bellemont Fault bisects Camp Navajo (Figure 2-3) and has 

been mapped as a single fault plane in much of this area (Wilkinson, 2000). Various other faults 

exist in the subsurface at Camp Navajo, including the Dunham Fault Zone, which cuts east to 

west across the northern portion of Camp Navajo (Thorstenson & Beard, 1998). 

During the SI, sandy clay was observed as the dominant lithology of the unconsolidated 

sediments below Camp Navajo. The borings were completed at depths between 6 and 40 feet 

bgs. Many of the logs also reported varying percentages of gravel and cobble, with a large 

percentage consisting of vesicular basalt. These results and facility observations are consistent 

with the reported depositional environment of the region. Boring logs are presented in Appendix 

E. 

2.2.2 Hydrogeology

The regional aquifer, composed of units including the Kaibab Formation, the Coconino Sandstone, 

and the Schnebly Hill/Supai Formations, has a highly variable water table ranging from 100 feet 

to over 2,000 feet bgs (Weston, 2018a).

In the Camp Navajo area, the depth to water in the regional aquifer is 1,500 to 1,700 feet bgs (US 

Army Corps of Engineers [USACE], 2015). Localized, shallow saturated zones of perched 

groundwater are found within the vicinity of Camp Navajo at typical depths of 10 to 20 feet bgs

(Weston, 2018b). Regional groundwater in the vicinity of Camp Navajo flows to the north (Weston, 

2018b) as seen in Figure 2-3. 

According to data obtained directly from the Arizona Department of Emergency and Military Affairs 

(AZDEMA) and Arizona Department of Water Resources (ADWR), there are monitoring wells and 

potable water wells on the installation and to the north of Camp Navajo. Additionally, there are 

approximately 200 wells within one mile of the installation’s boundary (Figure 2-4) (ADWR, 2019). 

Well depths outside of the Camp Navajo boundary range from 12 feet bgs to 2,801 feet bgs, and 

pumping rates range from 3 gallons per minute (gpm) to 250 gpm. The majority of wells outside 

the Camp Navajo boundary are listed as exempt or non-exempt. The State of Arizona describes 
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exempt wells as small, non-irrigation wells typically used to provide water for domestic purposes, 

and non-exempt wells as a well drilled within an Active Management Area pursuant to different 

groundwater rights. There are 707 wells (domestic, commercial, and industrial) within a 4-mile 

radius of the facility, 140 of which are downgradient (Figure 2-4).

Sources of potable water at Camp Navajo include the CN-2 well, Spring 1, Spring 2, Spring 3/3A, 

and Reservoir 1, which is fed by the springs (Figure 2-3). The springs are fed by shallow perched 

groundwater from the Wild Bill Hill basalt. This shallow groundwater is generally recharged via 

precipitation, flows from north to the south, and discharges at the springs. The facility has the 

ability to pull water from Reservoir 1. Water is stored primarily at the water tower, which has a 

capacity of 500,000 gallons, in addition to three man-made raw-water resources that can store an 

additional 20.8 million gallons (Jacobs, 2017). The maximum potable water available to the 

installation is 246,000 gallons per day (gpd); this includes domestic requirements of 150 gpd per 

person and enough to supply the fire suppression systems. 

2.2.3 Hydrology 

Camp Navajo is within the Verde River watershed, which consists of approximately 6,624 square 

miles of land (Arizona Department of Environmental Quality [ADEQ], 2019). Volunteer Wash is 

the main surface water drainage channel and has incised Volunteer Canyon in the southern 

portion of Camp Navajo as it flows to the south and eventually intersects Sycamore Canyon 

(USACE, 2015). Volunteer Wash and its tributaries are intermittent and only flow following heavy 

rainstorms or periods of snowmelt. Regional watersheds and surface drainage features within the 

vicinity of Camp Navajo are presented in Figure 2-5. 

Surface water on the facility is limited. There are no permanent, naturally occurring streams or 

lakes at Camp Navajo; however, there are several wetland areas, intermittent streams, natural 

springs, three perennially spring-fed man-made ponds, and earthen holding ponds. Most surface 

water does not leave the installation due to interruptions in surface flow, such as water tanks and 

sinkholes, that detain runoff (AZARNG, 2020).

All surface water runoff west of the Bellemont Fault (Figure 2-5) drains toward the ephemeral 

Atherton Lake, which overflows into two adjacent sinkholes. Sheet runoff from other areas drains 

towards the southeastern corner of the installation and eventually into the Volunteer Wash 

channel, which follows the Bellemont Fault (Wilkinson, 2000). All surface drainage paths at Camp 

Navajo eventually lead to infiltration or exit towards Volunteer Canyon to the south. 

2.2.4 Climate 

The climate of north-central Arizona is semiarid, and characterized by cold winters, mild summers, 

and low humidity. The majority of days and nights are clear to partly cloudy. Prevailing wind 

direction is south-southwest. The mean temperature is 45.6 degrees Fahrenheit (°F), with 

extreme temperatures up to at least 97 °F and down to at least -30 °F. Average annual 

precipitation is 22 inches, with the majority occurring from December to March and from July to 

September. Snowfall typically occurs between October and May, with average annual snowfalls 

of 102 inches. Some winters have recorded as little as 12 inches of total snow. Due to the dryness 

of the climate, evaporation causes a loss of 60 inches of water per year from exposed surfaces 

(AZARNG, 2020).

2.2.5 Current and Future Land Use

The Camp Navajo mission is “To operate a training site and storage facility at Bellemont, Arizona” 

(AZARNG, 2020). Camp Navajo supports this dual mission of training and storage and provides 

training to all military branches (training and reserve). Camp Navajo has 2.3 million square feet 
Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 2-4

of storage and provides capacity to both the Navy and Air Force (Jacobs, 2017). The facility is 

anticipated to remain used for military training and munitions storage in the future. Camp Navajo 

can be divided into four areas based on use:

• The Cantonment Area includes headquarters, training sites, the Field Maintenance Shop, 

and a warehouse area.

• The Limited Area stores various commodities and predominantly munitions. 

• The historic Open Burn/Open Detonation Area, used for demilitarization of munitions, is now 

referred to as the Post-Closure Permit Area.

• The fourth area is the Buffer Area, which was designed to provide safe distances between 

storage facilities and off-post land and is now used primarily for training.

2.2.6 Sensitive Habitat and Threatened/ Endangered Species 

The following amphibians, birds, fishes, insects, plants, mammals, reptiles, and snails are 

federally endangered, threatened, proposed, and/ or are listed as candidate species in Coconino 

County, Arizona (US Fish and Wildlife Service [USFWS], 2022). 

• Amphibians: Chiricahua Leopard Frog, Rana chiricahuensis (threatened)

• Birds: California Condor, Gymnogyps californianus (endangered); Mexican Spotted Owl, 

Strix occidentalis lucida (threatened); Southwestern Willow Flycatcher, Empidonax traillii 

extimus (endangered); Yellow-billed Cuckoo, Coccyzus americanus (threatened)

• Fishes: Apache Trout, Oncorhynchus apache (threatened); Gila Chub, Gila intermedia

(endangered); Gila Trout, Oncorhynchus gilae (threatened); Humpback Chub, Gila cypha

(threatened); Little Colorado Spinedace, Lepidomeda vittata (threatened); Loach Minnow, 

Tiaroga cobitis (endangered); Razorback Sucker, Xyrauchen texanus (endangered); 

Spikedace, Meda fulgida (endangered); Virgin River Chub, Gila seminuda (robusta)

(endangered)

• Insects: Monarch Butterfly, Danaus plexippus (candidate)

• Plants: Brady Pincushion Cactus, Pediocactus bradyi (endangered); Fickeisen Plains 

Cactus, Pediocactus peeblesianus fickeiseniae (endangered); Navajo Sedge, Carex 

specuicola (threatened); Peebles Navajo Cactus, Pediocactus peeblesianus ssp. 

peeblesianus (endangered); San Francisco Peaks Ragwort, Packera franciscana

(threatened); Sentry Milk-vetch, Astragalus cremnophylax var. cremnophylax (endangered); 

Siler Pincushion Cactus, Pediocactus (Echinocactus,Utahia) sileri (threatened); Ute ladies'-

tresses, Spiranthes diluvialis (threatened); Welsh's Milkweed, Asclepias welshii (threatened)

• Mammals: Black-footed Ferret, Mustela nigripes (endangered); Mexican Wolf, Canis lupus 

baileyi (endangered)

• Reptiles: Narrow-headed Gartersnake, Thamnophis rufipunctatus (threatened); Northern 

Mexican Gartersnake, Thamnophis eques megalops (threatened)

2.3 History of PFAS Use

Six potential release areas were identified at Camp Navajo during the PA, where AFFF may have 

been used or historically released (AECOM, 2020). Between 1994 and 2003, AFFF was used to 

extinguish intentional burns at two different buildings. Additionally, Camp Navajo operated two fire 

stations where potential releases occurred from washing firetrucks that carried AFFF, flushing out 
Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 2-5

lines used for AFFF discharge at other locations, and storage of AFFF. Secondary releases could 

have occurred via transport of impacted surface water and sediment, discharge of impacted water 

from Camp Navajo’s wastewater treatment plant (WWTP), and disposal of impacted WWTP 

sludge at the onsite landfill. From these secondary sources, releases could have migrated to 

groundwater and impacted the regional aquifer. The potential release areas were identified in six

AOIs based on preliminary data and assumed groundwater flow directions. A description of each 

AOI is presented in Section 3. 

2.4 Other PFAS Investigations

Since 2017 PFAS potable water source sampling has been performed under the direction of the 

AZARNG at Camp Navajo. Samples have been collected from Spring 1, Spring 2/3,Spring 3, and 

potable well CN-2 (pre-treatment and post-treatment). The last round of sampling was performed 

in July 2022, and the results for PFOA, PFOS, PFHxS, PFNA, and PFBS are reported in the Table 

2-1. Results indicated that detectable concentrations of PFOA, PFOS, PFHxS, and PFBS existed 

in the drinking water supplies. 

Table 2-1: July 2022 PFOA, PFOS, PFHxS, PFNA, and PFBS Sampling Results

Sample ID Date PFOA (ng/L) PFOS (ng/L) PFHxS (ng/L) PFNA (ng/L) PFBS (ng/L)

Spring 1

4/12/2017 3.21 J 13.7 14.3 ND 3.44 J

3/5/2018 2.7 16 NA NA NA

6/7/2018 2.8 14 NA NA NA

9/17/2018 2.1 19 NA NA NA

12/4/2018 2.3 25 NA NA NA

3/28/2019 7.1 17 NA NA NA

3/31/2020 1.9 10 11 ND (<1.8) 2.4

3/23/2022 2.09 17.6 15.8 ND (<2.00) 3.52

6/29/2022 ND (<1.72) 44.6 23.3 ND (<1.72) 16.8

Spring 2/3

4/12/2017 1.64 J 17.1 ND ND 3.61 J

3/5/2018 ND (<2.5) 63 NA NA NA

6/7/2018 ND (<2.5) 12 NA NA NA

9/17/2018 ND (<2.0) 16 NA NA NA

12/4/2018 2.5 30 NA NA NA

3/28/2019 3.3 28 NA NA NA

3/31/2020 1.8 56 17 ND (<1.7) 3.4

3/23/2022 1.75 30.1 26 ND (<1.69) 22.5

6/29/2022 ND (<1.76) 34.9 25.2 ND (<1.76) 9.62

Spring 3

4/12/2017 0.774 J 11.6 8.13 ND 2.14 J

3/5/2018 ND (<2.7) 12 NA NA NA

6/7/2018 ND (<2.5) 16 NA NA NA

9/17/2018 ND (<2.0) 16 NA NA NA

12/4/2018 ND (<2.0) 23 NA NA NA

3/28/2019 ND (<2.0) 19 NA NA NA

3/31/2020 1.5 J 16 12 ND (<1.8) 3.4

3/23/2022 ND (<1.72) 23.3 18.2 ND (<1.72) 37.3
Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 2-6

6/29/2022 ND (<1.77) 28.5 26.1 ND (<1.77) 9.49

Pre-treatment

4/12/2017 ND ND ND ND ND 

3/28/2019 7 17 NA NA NA

9/25/2019 ND (<2.0) ND (<2.0) NA NA NA

12/29/2019 ND (<2.0) ND (<2.0) NA NA NA

3/31/2020 ND (<1.9) ND (<1.9) ND (<1.9) ND (<1.9) ND (<1.9)

11/9/2021 ND (<1.6) ND (<1.6) ND (<1.6) ND (<1.6) ND (<1.6)

3/23/2022 ND (<1.68) 30.2 20.2 ND (<1.68) 24.2

6/29/2022 1.84 29.6 22 ND (<1.79) 13.9

Post-treatment

4/12/2017 3.80 J 14.1 15.6 ND 4.50 J

3/28/2019 6.9 18 NA NA NA

9/25/2019 2.4 13 NA NA NA

12/29/2019 3.3 16 NA NA NA

3/31/2020 2.4 11 11 ND (<1.8) 2.6

3/23/2022 2.26 23.8 22.3 ND (<1.85) 25.5

6/29/2022 ND (<1.81) 21.9 22.1 ND (<1.81) 10.7

Notes: 

NA = not analyzed

ND = not detected above the limit of quantitation

ng/L = nanograms per liter 

1. Pre-treatment is a sample taken directly from the CN-2 well head.
CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

AB

8/16/2022

8/16/2022

PROJECT Site Investigation at Camp Navajo, AZ

1:633,600

8/16/2022 ­ Figure 2-1 PM CM 8/16/2022

12420 Milestone Center Drive

Germantown, MD 20876

Facility Location

Base Map: USGS The National Map: National

Boundaries Dataset, 3DEP Elevation Program,

^_

0 5 10 20

Miles

Legend

Facility Boundary

Camp Navajo

AECOM 2-7
CLIENT

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ARNG

GIS BY

CHK BY

MS

AB

8/16/2022

8/16/2022

PROJECT Site Investigation at Camp Navajo, AZ

1:95,040

8/16/2022 ­ Figure 2-2 PM CM 8/16/2022

12420 Milestone Center Drive

Germantown, MD 20876

Site Topography

Base Map: Copyright:© 2013 National Geographic

Society, i-cubed

0 0.75 1.5 3

Miles

Legend

Facility Boundary

AECOM 2-8
Volunteer Wash

Rogers Lake

South Sink

Atherton Lake

Reservoir Number One

Spring 2

Spring 1 Spring 3A

Spring 3

JD

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as h

Volunte er Was h

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Sy camor eCreek

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Water Body

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Pipeline

Inferred Groundwater Flow

Direction

Geology

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Holocene to Middle Pliocene

Basaltic Rocks

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Basaltic Rocks

Permian Sedimentary Rocks

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Groundwater Features

Figure 2-3 12420 Milestone Center Drive ­ Germantown, MD 20876

CLIENT

REVISED

SCALE

9/7/2022 MS

AB

9/7/2022

9/7/2022

ARNG

GIS BY

CHK BY

PROJECT Site Investigation at Camp Navajo, AZ

PM CM 9/7/2022

1:190,080

Base Map: National Agricultural Imagery Program, 2017. Source: Esri, Maxar, Earthstar

Geographics, and the GIS User Community

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Figure 2-4 12420 Milestone Center Drive ­ Germantown, MD 20876

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Base Map: National Agricultural Imagery Program, 2017. Source: Esri, Maxar, Earthstar

Geographics, and the GIS User Community

Exempt wells are typically used for potable purposes. Non-exempt wells

typically provide higher volumes of water for irrigation or other purposes.

AECOM 2-10
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Figure 2-5 12420 Milestone Center Drive ­ Germantown, MD 20876

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AECOM 2-11
AECOM 2-12

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Site Inspection Report

Camp Navajo, Bellemont, Arizona
Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 3-1

3. Summary of Areas of Interest

The PA evaluated areas where PFAS-containing materials may have been used, stored, 

disposed, or released historically. Based on the PA findings, six potential release areas were 

identified at Camp Navajo and grouped into six AOIs (AECOM, 2020). The potential release areas 

are shown on Figure 3-1. 

3.1 AOI 1 Former Building 209

AOI 1 is the Former Building 209, former fire station, which is located in the 200 Area in the 

northern portion of the facility. According to interviews conducted during the PA site visit and aerial 

photographs, Building 209 was demolished between 2000 – 2003. No information was obtained 

about the operation of the fire station at Building 209; however, it is likely that similar operations 

took place at Building 209 that had taken place at Building 2 during its operation as a fire station. 

These activities may have included washing firetrucks that carried AFFF, flushing out lines used 

for AFFF discharge at other locations, and storage of AFFF. It was reported that AFFF was most 

likely used during the intentional burn of Building 209. The amount of AFFF used during this 

training exercise is unknown. A Macy Firetruck was used for installation firefighting activities and 

was likely used to extinguish the Building 209 fire. Camp Navajo’s Macy Firetruck had a 600-

gallon water tank and a 60-gallon foam tank. 

3.2 AOI 2 Former Building LR200

AOI 2 is the Former Building LR200, which is located in the northern portion of the facility in the 

storage area. Building LR200 was used as a lunchroom prior to being demolished by intentional 

burn. An unknown quantity of AFFF was likely used to suppress the fire. The exact date of the fire 

training exercise that demolished the building is not known; however, Camp Navajo personnel 

recall the training exercise. The Former Building LR200 area is currently used as a storage field 

for construction materials. To the northeast of LR200 is the South Sink which is a large, but 

inactive sinkhole. There is an ephemeral stream which flows towards the South Sink and is a flow 

path from LR200. Most sinks in the area have fractured bedrock and colluvium in the walls and 

bottom. 

3.3 AOI 3 Building 2

AOI 3 is Building 2, former fire station, which is located in the Cantonment Area in the northern 

portion of the facility. Building 2 was constructed in 1942 and was used as a fire station after 

Building 209 was destroyed. The use of Building 2 as a fire station continued until approximately 

2012, when the new fire station was constructed. Firetrucks and hose lines were flushed, rinsed, 

and washed outside of Building 2 in the parking lot. No staining or residue were observed within 

the Building 2 area during the PA site visit. According to interviewees, AFFF was stored inside the 

fire station and was used in a Macy Firetruck, which was parked at the station. 

It is likely that residual AFFF entered two storm drains in the parking lot. According to aerial 

imagery, in 2007 Building 2 had about 50-foot wide swaths of bare earth along the southern and 

eastern edges of its footprint. Those areas of bare earth were located directly adjacent to paved 

roads and the parking lot.
Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 3-2

3.4 AOI 4 WWTP Holding Ponds and Effluent Reuse Site

AOI 4 is the WWTP Holding Ponds and Effluent Reuse Area, which are located in the northern 

portion of the facility to the south of the WWTP. This AOI is a secondary potential release area. It 

is believed that AFFF released from the 200 Area during fire station maintenance activities entered 

abandoned storm drains and sewer lines leading to the WWTP. As a result, PFAS-contaminated 

effluent may have been discharged to the WWTP Holding Ponds. The currently used WWTP 

Holding Pond Aerial imagery suggests the old ponds were in use through 2007 and that the new 

pond was constructed between 1992 – 2003. Aerial imagery suggests the new pond began to 

receive effluent at least as early as 2005. The holding ponds are earthen areas where water is 

held to infiltrate and evaporate.

3.5 AOI 5 NAAD-40

AOI 5 is NAAD-40, the former sanitary landfill, which is located in the northern portion of the 

facility. This AOI is a secondary potential release area. The landfill accepted sludge from the 

WWTP, which may have been impacted by AFFF releases in the 200 Area and Cantonment Area. 

The NAAD-40 landfill is unlined; therefore, leaching of PFAS-containing material from WWTP 

sludge in the landfill to the water table may have occurred. The 2015 Five Year Review identifies 

a perched water table below AOI 5 (USACE, 2015). This shallow aquifer is potentially hydraulically 

connected to shallow aquifers off the facility that feed private potable wells. To take a conservative 

approach, this shallow aquifer may also be in communication with the deep regional aquifer. This 

shallow aquifer is potentially hydraulically connected to the springs (Springs 1, 2, and 3/3A).

3.6 AOI 6 North and South Holding Ponds

AOI 6 comprises the North and South Holding Ponds located in the Cantonment Area in the 

northern portion of the facility. Both holding ponds are ephemeral and receive storm water runoff 

from the Cantonment Area, specifically Building 2, where AFFF discharges have occurred. 

The Cantonment Area Holding Ponds are located at a lower elevation than the Cantonment Area, 

and they drain further east toward a creek and eventually south toward Volunteer Wash. Due to 

the documented presence and discharge of AFFF at Building 2, there is a possible pathway from 

the storm drains at Building 2 to the Cantonment Area Holding Ponds, and subsequently off the 

facility. 
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­ Figure 3-1

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1:14,400

Area of Interest

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Areas of Interest

12420 Milestone Center Drive

Germantown, MD 20876

AECOM 3-3
AECOM 3-4

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Site Inspection Report

Camp Navajo, Bellemont, Arizona
Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 4-1

4. Project Data Quality Objectives

As identified during the Data Quality Objective (DQO) process and outlined in the SI Quality 

Assurance Project Plan (QAPP) Addendum (AECOM, 2021a), the objective of the SI is to identify 

whether there has been a release to the environment at the AOIs identified in the PA. For each 

AOI, ARNG determines if further investigation is warranted, a removal action is required to 

address immediate threats, or whether no further action is warranted. This SI evaluated 

groundwater and soil for presence or absence of relevant compounds at each of the sampled 

AOIs.

4.1 Problem Statement

ARNG will recommend an AOI for Remedial Investigation (RI) if related soil and groundwater 

samples have concentrations of the relevant compounds above the OSD risk-based SLs. The 

SLs are presented in Section 6.1 of this report. 

4.2 Information Inputs

Primary information inputs included:

• The PA for Camp Navajo (AECOM, 2020); 

• Analytical data collected under direction of the ARNG from Camp Navajo’s drinking water 

system. 

• Analytical data from groundwater, surface water, sediment, and soil samples collected as 

part of this SI in accordance with the site-specific Uniform Federal Policy (UFP)-QAPP 

Addendum (AECOM, 2021a); and

• This includes the compliance sampling performed by the AZARNG of the potable 

water sources at Camp Navajo. It should be noted that this data has undergone Level 

2 data validation by the laboratory, but has not undergone any additional external 

validation. 

• Field data collected during the SI, including groundwater elevation and water quality 

parameters measured at the time of sampling. 

4.3 Study Boundaries

The scope of the SI was bounded by the property limits of the facility (Figure 2-2). Off-facility sampling 

was not included in the scope of this SI. If future off-facility sampling is required, the proper 

stakeholders will be notified, and necessary rights of entry will be obtained by ARNG with property 

owner(s). Temporal boundaries were limited to the spring season, which was the earliest available 

time field resources were available to complete the study. 

4.4 Analytical Approach

Samples were analyzed by Pace Analytical Gulf Coast, accredited under the Department of 

Defense (DoD) Environmental Laboratory Accreditation Program (ELAP; Accreditation Number 

74960) and the National Environmental Laboratory Accreditation Program (NELAP; Certificate

Number 01955). Data were compared to applicable SLs within this document and decision rules 

as defined in the SI QAPP Addendum (AECOM, 2021a). 
Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 4-2

4.5 Data Usability Assessment

The Data Usability Assessment (DUA), which is provided in Appendix A, is an evaluation at the 

conclusion of data collection activities that uses the results of both data verification and validation 

in the context of the overall project decisions or objectives. Using both quantitative and qualitative 

methods, the assessment determines whether project execution and the resulting data have met 

installation-specific DQOs. Both sampling and analytical activities are considered to assess 

whether the collected data are of the right type, quality, and quantity to support the decisionmaking (DoD, 2019a; DoD, 2019b; USEPA, 2017). 

Based on the DUA, the environmental data collected during the SI were found to be acceptable 

and usable for this SI evaluation with the qualifications documented in the DUA and its associated 

data validation reports. These data are of sufficient quality to meet the objectives and 

requirements of the SI QAPP Addendum (AECOM, 2021a). 

It should be noted that the water collected from these the AOI 5 existing monitoring wells was 

collected below the well screen (stagnant water) and are not low-flow samples representative of 

formation water. Under normal circumstances, these samples would not used for decision making 

purposes; however, in lieu of not collecting samples and having no data, the samples were 

collected and consider acceptable (for screening purposes only) to determine presence or 

absence of PFAS
Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 5-1

5. Site Inspection Activities

This section describes the environmental investigation and sampling activities that occurred as 

part of the SI. The SI sampling approach was based on the findings of the PA and implemented 

in accordance with the following approved documents: 

• Final Site Inspection Programmatic Uniform Federal Policy-Quality Assurance Project Plan 

(PQAPP) dated March 2018 (AECOM, 2018a);

• Final Programmatic Accident Prevention Plan dated July 2018 (AECOM, 2018b); 

• Final Preliminary Assessment Report, Camp Navajo, Arizona dated September 2020

(AECOM, 2020); 

• Final Site Inspection Uniform Federal Policy-Quality Assurance Project Plan Addendum, 

Camp Navajo dated April 2021 (AECOM, 2021a); and

• Final Site Safety and Health Plan, Camp Navajo dated May 2021 (AECOM, 2021b). 

The SI field activities were conducted from 24 May to 3 June 2021 and consisted of utility clearance, 

soil boring installation and sampling via hollow stem auger (HSA), grab groundwater sample 

collection, and sediment and surface water sample collection. Field activities were conducted in 

accordance with the SI QAPP Addendum (AECOM, 2021a), except as noted in Section 5.9. 

The following samples were collected during the SI and analyzed for a subset of 18 compounds

by liquid chromatography with tandem mass spectrometry (LC/MS/MS) compliant with Quality 

Systems Manual (QSM) 5.3 Table B-15 to fulfill the project DQOs:

• Thirty-six (36) soil samples from 23 boring locations; 

• Four grab groundwater samples from four permanent monitoring wells; 

• One sediment and one surface water sample from one location; 

• Five spring samples from five natural spring locations; and 

• Twenty-seven (27) quality assurance (QA)/quality control (QC) samples.

Figure 5-1 through Figure 5-4 provide the sample locations for all media across the facility. Table 

5-1 presents the list of samples collected for each media. Field documentation is provided in 

Appendix B. A Log of Daily Notice of Field Activity was completed throughout the SI field 

activities, which is provided in Appendix B1. Sampling forms are provided in Appendix B2, Field 

Change Request Forms are provided in Appendix B3, a Nonconformance and Corrective Action 

Report is provided in Appendix B4, and investigation-derived waste (IDW) polygons are provided 

in Appendix B5. Additionally, a photographic log of field activities is provided in Appendix C. 

5.1 Pre-Investigation Activities

In preparation for the SI field activities, project team members participated in Technical Project 

Planning (TPP) meetings, performed utility clearance, and sampled decontamination source 

water. Details for each of these activities are presented below.

5.1.1 Technical Project Planning

The USACE TPP Process, Engineer Manual (EM) 200-1-2 (USACE, 2016) defines four phases 

to project planning: 1.) defining the project phase; 2.) determining data needs; 3.) developing data 
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Camp Navajo, Bellemont, Arizona

AECOM 5-2

collection strategies; and 4.) finalizing the data collection plan. The process encourages 

stakeholder involvement in the SI, beginning with defining overall project objectives, including 

DQOs, and formulating a sampling approach to address the AOIs identified in the PA. 

A combined TPP Meeting 1 and 2 was held on 11 January 2021, prior to SI field activities. The 

combined TPP Meeting 1 and 2 was conducted in general accordance with EM 200-1-2. The 

stakeholders for this SI include the ARNG, AZARNG, USACE, ADEQ, and representatives familiar 

with the facility, the regulations, and the community. Stakeholders were provided the opportunity 

to make comments on the technical sampling approach and methods at the combined TPP 

Meeting 1 and 2. The outcome of the combined TPP Meeting 1 and 2 was memorialized in the SI 

QAPP Addendum (AECOM, 2021a). 

A TPP Meeting 3 was held 14 April 2022 after the field event to discuss the results of the SI.

Meeting minutes for TPP 3 are included in Appendix D of this report. Future TPP meetings will 

provide an opportunity to discuss the results and findings, and future actions, where warranted. 

5.1.2 Utility Clearance 

Utility clearance was conducted by Camp Navajo personnel, with input from the AECOM field 

team. AECOM’s drilling subcontractor, Cascade Technical Services, LLC. placed a ticket with the 

Arizona 811 utility clearance provider to notify them of intrusive work on 19 May 2021. Additionally, 

the first 5 feet of each boring were pre-cleared using a hand auger to verify utility clearance in 

shallow subsurface where utilities would typically be encountered. 

5.1.3 Source Water and Sampling Equipment Acceptability

A potable water source at Camp Navajo was sampled on 18 February 2021 to assess usability 

for decontamination of drilling equipment. Results of the sample (CN-PW-01) collected from the 

sample tap at the onsite potable production well, CN-2, pumphouse confirmed this source to be 

acceptable for use in this investigation; therefore, it was used throughout the field activities.

Specifically, the samples were analyzed by LC/MS/MS compliant with QSM 5.3 Table B-15. The 

results of the decontamination water sample associated with the potable production well source 

used during the SI are provided in Appendix F. A discussion of the results is presented in the 

DUA (Appendix A).

Materials that were used within the sampling zone were confirmed as acceptable for use in the 

sampling environment. The checklist of acceptable materials for use in the sampling environment 

was provided in the Standard Operating Procedures appendix to the SI QAPP Addendum 

(AECOM, 2021a). Prior to the start of field work each day, a Sampling Checklist was completed 

as an additional layer of control. The checklist served as a daily reminder to each field team 

member regarding the allowable materials within the sampling environment. 

5.2 Soil Borings and Soil Sampling

Borings were installed in grass or dirt areas, where applicable, to avoid disturbing concrete or 

asphalt surfaces. Soil samples were collected via hand auger and HSA, in accordance with the 

SI QAPP Addendum (AECOM, 2021a). Hand augers were used at locations designated for 

collection of surface soil samples (0 to 2 feet bgs). Borings were advanced using HSA at locations 

designated for subsurface soil sample collection; however, hand augers were used to collect soil 

from the top 5 feet of the boring, in accordance with AECOM utility clearance procedures. At 

subsurface soil boring locations, a track-mounted CME-85 was used to collect soil (via split spoon) 

every five feet to the target depth, or until refusal was encountered. The soil boring locations are 

shown on Figure 5-1 through Figure 5-4, and depths are provided Table 5-1. 
Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 5-3

Three discrete soil samples were collected for chemical analysis per boring, except where refusal 

was encountered at 6 feet bgs, only allowing two soil samples to be collected. This situation 

occurred at several sample locations and these deviations are described in Section 5.9. One 

shallow soil sample at approximately 5 feet bgs, one mid-point soil sample between the surface 

and total boring depth, and one sample at target depth (or approximately 1-foot above refusal) 

were collected at each boring via split spoon. The soil cores were logged for lithological 

descriptions by an AECOM field geologist using the Unified Soil Classification System (USCS). A 

photoionization detector (PID) was used to screen the breathing zone during boring activities as 

part of personal safety requirements. Observations and measurements were recorded on 

sampling forms (Appendix B2) and in a non-treated field logbook (i.e., composition notebook). 

Depth interval, recovery thickness, PID concentrations, moisture, relative density, color (using a 

Munsell soil color chart), and texture (using the USCS) were recorded. The boring logs are 

provided in Appendix E. 

Soil borings completed during the SI encountered sandy clay as the dominant lithology of the 

unconsolidated soil below Camp Navajo. The borings were completed at depths between 6 and 

40 feet bgs. Many of the logs also reported varying percentages of gravel and cobble, consisting 

of vesicular basalt. These observations are consistent with the understood depositional 

environment of the region.

Each soil sample was collected into laboratory-supplied PFAS-free high-density polyethylene 

(HDPE) bottles and labeled using a PFAS-free marker or pen. Samples were packaged on ice 

and transported via Federal Express (FedEx) under standard chain of custody (CoC) procedures 

to the laboratory and analyzed by LC/MS/MS compliant with QSM 5.3 Table B-15, total organic 

carbon (TOC) (USEPA Method 9060A), and pH (USEPA Method 9045D), in accordance with the 

SI QAPP Addendum (AECOM, 2021a).

Field duplicate samples were collected at a rate of 10 percent (%) and analyzed for the same 

parameters as the accompanying samples. Matrix spike (MS)/MS duplicates (MSDs) were 

collected at a rate of 5% and analyzed for the same parameters as the accompanying samples. 

In instances when non-dedicated sampling equipment was used, such as a hand auger for the 

shallow soil samples, equipment rinsate blanks (ERBs) were collected at a rate of 5% and 

analyzed for the same parameters as the soil samples. A temperature blank was placed in each 

cooler to ensure that samples were preserved at or below 6 degrees Celsius (°C) during shipment.

Upon completion of soil sample collection, borings were abandoned by backfilling with bentonite 

chips and dressed at the surface with soil cuttings. At locations where asphalt was disturbed, the 

borehole was patched with cold patch asphalt to match existing grade. 

5.3 Groundwater Grab Sampling

Temporary and permanent monitoring installation were attempted at eight locations across the 

facility. However, no monitoring wells were installed due to bedrock refusal and lack of waterbearing lenses in the unconsolidated soil. 

Four existing monitoring wells (PMW-1, PMW-2, PMW-4, and FSL-5) were sampled at AOI 5 on 

1 June and 2 June 2021. The well locations are shown on Figure 5-1 and Figure 5-4. Sampling 

was completed in accordance with the SI QAPP Addendum (AECOM, 2021a). Samples were 

collected using a QED Sample Pro® bladder pump with disposable PFAS-free, HDPE tubing at 

all wells except PMW-4. The water level was insufficient to use a bladder pump at PMW-4;

therefore, a peristaltic pump with disposable PFAS-free silicon and HDPE tubing was used to 

collect a sample. New tubing was used at each well and the pump was decontaminated between 

each well. Water quality parameters (e.g., temperature, specific conductance, pH, dissolved 

oxygen [DO], oxidation-reduction potential [ORP], and turbidity) were measured using a water 

quality meter and recorded on the field sampling form (Appendix B2). Water levels were 
Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 5-4

measured to the nearest 0.01 inch and recorded. Additionally, a subsample of each groundwater 

sample was collected in a separate container, and a shaker test was completed to identify if there 

were any foaming. No foaming was noted in any of the groundwater samples.

5.4 Spring Sampling

Five natural springs which are fed by the perched aquifer underlying AOI 1, AOI 3, and potentially 

AOI 6 were sampled on 2 June 2021. The locations of these springs are shown on Figure 5-1. 

Spring samples were collected using a peristaltic pump with PFAS-free HDPE tubing. Water 

quality parameters (e.g., temperature, specific conductance, pH, DO, ORP, and turbidity) were 

measured using a water quality meter and recorded on the field sampling form (Appendix B2) 

after each grab sample was collected. Additionally, a subsample of each spring sample was

collected in a separate container, and a shaker test was completed to identify if there were any 

foaming. No foaming was noted in any of the spring samples. 

Each sample was collected into laboratory-supplied PFAS-free HDPE bottles and labeled using 

a PFAS-free marker or pen. Samples were packaged on ice and transported via FedEx under 

standard CoC procedures to the laboratory for analysis by LC/MS/MS compliant with QSM 5.3 

Table B-15 in accordance with the SI QAPP Addendum (AECOM, 2021a). 

Groundwater field duplicate samples were collected at a rate of 10% and analyzed for the same 

parameters as the accompanying samples. MS/MSDs were collected at a rate of 5% and 

analyzed for the same parameters as the accompanying samples. In instances when nondedicated sampling equipment was used, equipment rinsate blank samples were collected at a 

rate of 5% and analyzed for the same parameters as the soil samples. A temperature blank was 

placed in each cooler to ensure that samples were preserved at or below 6 °C during shipment.

5.5 Surface Water and Sediment Sampling

One surface water sample and one sediment sample were collected from Atherton Lake. The 

sample location is shown on Figure 5-1. 

The sediment sample was co-located with the surface water sample and collected in accordance 

with the SI QAPP Addendum (AECOM, 2021a). The surface water sample was collected from a 

single point in the waterbody by dipping a Ziploc bag into the water, approximately two-thirds up 

from the bottom of the water body, and subsequently transferring the water into laboratorysupplied bottles. For the co-located surface water and sediment samples, the surface water 

sample was collected before the co-located sediment sample. Sampling was performed 

deliberately and methodically to minimize disturbance of bottom sediments and as quickly as 

possible to ensure a representative sample was collected. Additionally, a subsample of the

surface water sample was collected in a separate container, and a shaker test was completed to 

identify if there were any foaming. No foaming was noted on the surface water sample.

After collection of the surface water sample, a sediment coring device (hand auger) was used to 

collect the sediment sample from the first foot of sediment. The sediment was transferred to a 

Ziploc bag, where the sample was homogenized and stones in excess of 1 centimeter were 

removed. After collection of the surface water and sediment samples from each location, general 

water quality parameters (e.g., temperature, specific conductance, pH, DO, ORP, and turbidity) 

were collected with a water quality meter and recorded on the field sampling form (Appendix B2).

The surface water and sediment sample locations are shown on Figure 5-1, and sample depths 

are provided in Table 5-1. 

Each sample was collected into laboratory-supplied PFAS-free HDPE bottles and labeled using 

a PFAS-free marker or pen. Samples were packaged on ice and transported via FedEx under 
Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 5-5

standard CoC procedures to the laboratory for analysis by LC/MS/MS compliant with QSM 5.1 

Table B-15. Sediment samples were also analyzed for TOC (USEPA Method 9060A) and pH 

(USEPA Method 9045D), in accordance with the SI QAPP Addendum (AECOM, 2021a). 

Field duplicate samples were collected at a rate of 10% and analyzed for the same parameters 

as the accompanying samples. MS/MSDs were collected at a rate of 5% and analyzed for the 

same parameters as the accompanying samples. In instances when non-dedicated sampling 

equipment was used, ERB samples were collected at a rate of 5% and analyzed for the same 

parameters as the soil samples. A temperature blank was placed in each cooler to ensure that 

samples were preserved at or below 6°C during shipment. 

5.6 Water Level Measurements

A groundwater gauging event was performed at AOI 5 on 1 June and 2 June 2021. Groundwater 

elevation measurements were collected from the five existing monitoring wells. Water level 

measurements were taken from the northern side of the well casing. Groundwater elevation data 

are provided in Table 5-2. 

5.7 Investigation-Derived Waste

As of the date of this report, the disposal of IDW is not regulated federally. IDW generated during 

the SI is considered non-hazardous waste and was managed in accordance with the SI QAPP 

Addendum (AECOM, 2021a) and with the DAGuidance for Addressing Releases of PFAS, Q18 (DA, 

2018). 

Soil IDW (i.e., soil cuttings) generated during the SI activities were left in place at the point of the 

source. The soil cuttings were returned to the borehole as backfill or distributed on the ground 

surface on the downgradient side of the boring. The soil IDW was not sampled and assumes the 

characteristics of the associated soil samples collected from that source location. 

Liquid IDW generated during SI activities (i.e., purge water, development water, and 

decontamination fluids) were containerized in two 55-gallon drums and stored onsite in the drum 

storage area next to the Environmental Office at Building 15. The liquid IDW was not sampled 

and assumes the characteristics of the associated groundwater samples collected from that 

source location.

Geographic coordinates were collected using a global positioning system around each location 

where IDW was placed (i.e., an IDW polygon). The IDW polygons are displayed on the figure in 

Appendix B5. 

Other solids such as spent personal protective equipment, plastic sheeting, tubing, rope, unused 

monitoring well construction materials, and other environmental media generated during the field 

activities were disposed of at a licensed solid waste landfill.

5.8 Laboratory Analytical Methods

Samples were analyzed for PFAS by LC/MS/MS compliant with QSM 5.3 Table B-15 at Pace 

Analytical Gulf Coast in Baton Rouge, Louisiana, a DoD ELAP and NELAP certified laboratory.

Soil samples were also analyzed for TOC using USEPA Method 9060A and pH by USEPA Method 

9045D. 
Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 5-6

5.9 Deviations from SI QAPP Addendum

Deviations from the SI QAPP Addendum occurred based on field conditions and discussion 

between AECOM, ARNG, and USACE. Deviations from the SI QAPP Addendum are noted below

and are documented in the Field Change Requests and Nonconformance and Corrective Action 

Report (Appendix B3 and B4):

As a result of the site walk on 24 May 2021, the following changes were proposed via Field Change 

Request Forms submitted to and later approved by ARNG and USACE. 

• During the site walk, the team walked along the drainage ditch immediately behind and 

downhill of the AOI 1 release area and determine AOI01-05 would be better located in a low 

spot adjacent to an outfall rather than the proposed location along the northern boundary of 

the 200 Area. This action was documented in a Field Change Request form and is provided 

in Appendix B3. 

• The surface water/sediment location in Atherton Lake was shifted approximately 75 feet 

west of the original location to avoid areas of cultural significance (move approved by 

AZARNG cultural resources personnel). The new location was positioned at a point of safe 

entry to access the water’s edge. This action was documented in a Field Change Request 

form and is provided in Appendix B3. 

• Due to ongoing construction in the area of AOI 2, it is likely any permanent well installed 

in the AOI 2 area would be buried or destroyed. Therefore, the team decided that if AOI02-

01 was installed, it should be a temporary well and a grab groundwater sample collected. 

Additionally, the team agreed to relocate AOI02-02 and AOI02-03 along a drainage ditch 

where surface water flows from the release area to the South Sink. The original location of 

AOI02-04 was found to be duplicative and was removed from the list of samples. This action 

was documented in a Field Change Request form and is provided in Appendix B3. 

Additionally, proposed surface water/sediment sampling location AOI02-05 was found to 

be dry. As a result, AOI02-05 was converted to a soil sample location and relabeled as 

AOI02-04. 

• AOI04-01 is located in a retention basin much lower in elevation than the surrounding 

ground surface. The drill rig would not be able to traverse the slope into the basin. 

Additionally, Camp Navajo personnel indicated that bedrock was expected to be close to 

the surface (< 5 feet bgs) inside the retention basin and a boring/monitoring well was not 

likely to be installed due to shallow refusal. The team agreed to convert AOI04-01 from a 

boring/monitoring well into a hand auger surface soil location (0-2 feet bgs). Additionally, 

AOI04-08 was moved approximately 200-300 feet east of the originally proposed location 

to be in the low spot near the reclaimed water discharge pipe. This action was documented 

in a Field Change Request form and is provided in Appendix B3. 

• The team agreed to move AOI06-01 to a low spot between the North and South Holding 

Ponds downgradient of both holding pond outfalls. This action was documented in a Field 

Change Request form and is provided in Appendix B3. 

• After gauging the wells at AOI 5, the AECOM field team found that PMW-3 and PMW-5 

were dry. Additionally, wells PMW-1, PMW-2, and PMW-4 had limited water (saturated 

thickness between 0.4 - 2 feet), and it was not possible to low-flow sample since the water 

was below the screen interval. As a result, grab groundwater samples were collected at two 

proposed wells, and a third was collected at PMW-4, which was not originally proposed for 

sampling. This action was documented in a Field Change Request form and is provided in 

Appendix B3. 
Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 5-7

• The SI QAPP Addendum stated that three soil samples were to be collected from each HSA 

boring locations. However, refusal was encountered at 17 feet bgs at boring location AOI01-

01. Soil from the 3-5 feet bgs and 8-10 feet bgs intervals were inadvertently not saved; 

therefore, only soil samples could only be collected from two intervals (0-2 feet bgs and 13-

15 feet bgs) instead of three intervals. This action was documented in a Nonconformance 

and Corrective Action Report and is provided in Appendix B4. 
Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 5-8

THIS PAGE INTENTIONALLY BLANK
Table 5-1

Samples by Medium

Site Inspection Report

Camp Navajo, Bellemont, Arizona

Sample Identification

Sample

Collection 

Date/Time

Sample Depth 

(ft bgs)

LC/MS/MS compliant with QSM 5.3 Table B-15TOC(USEPA Method 9060A)pH (USEPA Method 9045D)

Comments

AOI01-01-SB-0-2 5/25/2021 11:20 0-2 x

AOI01-01-SB-13-15 5/25/2021 12:50 13-15 x

AOI01-01-SB-13-15-D 5/25/2021 12:50 13-15 x FD

AOI01-02-SB-0-2 5/26/2021 7:30 0-2 x

AOI01-02-SB-8-10 5/26/2021 8:35 8-10 x

AOI01-02-SB-8-10-D 5/26/2021 8:35 8-10 x FD

AOI01-02-SB-13-15 5/26/2021 8:45 13-15 x

AOI01-03-SB-0-2 5/25/2021 14:00 0-2 x

AOI01-03-SB-3-5 5/25/2021 14:45 3-5 x

AOI01-03-SB-8-10 5/25/2021 14:53 8-10 x

AOI01-04-SB-0-1.7 5/26/2021 9:15 0-1.7 x x x

AOI01-05-SB-0-1.7 5/26/2021 10:05 0-1.7 x

AOI02-01-SB-0-2 5/27/2021 10:20 0-2 x x x

AOI02-01-SB-0-2-MS 5/27/2021 10:20 0-2 x MS

AOI02-01-SB-0-2-MSD 5/27/2021 10:20 0-2 x MSD

AOI02-01-SB-18-20 5/27/2021 10:50 18-20 x

AOI02-01-SB-33-35 5/27/2021 11:30 33-35 x

AOI02-02-SB-0-2 5/28/2021 9:38 0-2 x

AOI02-03-SB-0-2 5/28/2021 9:58 0-2 x

AOI02-04-SB-0-1 5/28/2021 10:16 0-1 x

AOI03-01-SB-0-2.5 5/26/2021 13:56 0-2.5 x

AOI03-01-SB-3-5 5/26/2021 14:05 3-5 x

AOI03-02-SB-0-2 5/26/2021 10:45 0-2 x

AOI03-02-SB-8-10 5/26/2021 11:15 8-10 x

AOI03-02-SB-20-22 5/26/2021 11:45 20-22 x

AOI03-03-SB-0-2 5/26/2021 15:07 0-2 x x x

AOI03-03-SB-0-2-MS 5/26/2021 15:07 0-2 x MS

AOI03-03-SB-0-2-MSD 5/26/2021 15:07 0-2 x MSD

AOI03-03-SB-8-10 5/26/2021 15:24 8-10 x

AOI03-03-SB-23-25 5/26/2021 15:46 23-35 x

AOI04-01-SB-0-0.5 6/1/2021 9:15 0-0.5 x

AOI04-02-SB-0-2 6/1/2021 8:52 0-2 x

AOI04-03-SB-0-0.75 6/1/2021 8:38 0-0.75 x

AOI04-04-SB-0-0.75 6/1/2021 10:36 0-0.75 x

AOI04-05-SB-0-0.75 6/1/2021 10:00 0-0.75 x

AOI04-06-SB-0-2 6/1/2021 10:20 0-2 x

AOI04-07-SB-0-1 6/1/2021 9:45 0-1 x

AOI04-08-SB-0-2 5/28/2021 10:55 0-2 x x x

AOI04-08-SB-0-2-D 5/28/2021 10:55 0-2 x FD

AOI06-01-SB-0-2 5/27/2021 7:47 0-2 x

AOI06-01-SB-3-5 5/27/2021 7:55 3-5 x

AOI06-02-SB-0-0.75 5/27/2021 8:15 0-0.75 x

AOI06-02-SB-0-0.75-D 5/27/2021 8:15 0-0.75 x FD

AOI06-03-SB-0-1.25 5/27/2021 8:30 0-1.25 x x x

AOI06-03-SB-0-1.25-D 5/27/2021 8:30 0-1.25 x x FD

AOI06-03-SB-0-1.25-MS 5/27/2021 8:30 0-1.25 x x MS

AOI06-03-SB-0-1.25-MSD 5/27/2021 8:30 0-1.25 x x MSD

Soil Samples

AECOM 5-9
Table 5-1

Samples by Medium

Site Inspection Report

Camp Navajo, Bellemont, Arizona

Sample Identification

Sample

Collection 

Date/Time

Sample Depth 

(ft bgs)

LC/MS/MS compliant with QSM 5.3 Table B-15TOC(USEPA Method 9060A)pH (USEPA Method 9045D)

Comments

AL-01-SD-0-0.2 6/1/2021 8:10 NA x

AL-01-SD-0-0.2-D 6/1/2021 8:10 NA x FD

AL-01-SD-0-0.2-MS 6/1/2021 8:10 NA x MS

AL-01-SD-0-0.2-MSD 6/1/2021 8:10 NA x MSD

AL-01-SW 6/1/2021 7:45 NA x

AL-01-SW-D 6/1/2021 7:45 NA x FD

AL-01-SW-MS 6/1/2021 7:45 NA x MS

AL-01-SW-MSD 6/1/2021 7:45 NA x MSD

FSL-5-060121 6/1/2021 13:00 56.6-121.6 x

FSL-5-060121-D 6/1/2021 13:00 56.6-121.6 x FD

PMW-1-060221 6/2/2021 8:50 11.5-31.5 x

PMW-2-060221 6/2/2021 9:20 4.75-24.75 x

PMW-4-060221 6/2/2021 8:30 4.75-24.75 x

SPG-01-GW 6/2/2021 13:20 NA x

SPG-02-GW 6/2/2021 13:40 NA x

SPG-03-GW 6/2/2021 14:20 NA x

SPG-03-GW-MS 6/2/2021 14:20 NA x MS

SPG-03-GW-MSD 6/2/2021 14:20 NA x MSD

SPG-04-GW 6/2/2021 14:30 NA x

SPG-05-GW 6/2/2021 14:55 NA x

CN-PW-01 2/18/2021 12:37 NA x Decon water source

CN-ERB-01 5/26/2021 14:30 NA x ERB on hand auger (Driller)

CN-ERB-02 5/26/2021 14:32 NA x ERB on HSA

CN-ERB-03 5/26/2021 14:34 NA x ERB on HSA split spoon

CN-ERB-04 6/1/2021 10:42 NA x ERB on hand auger (AECOM)

CN-ERB-05 6/2/2021 9:54 NA x ERB on bladder pump

CN-FRB-01 6/1/2021 13:20 NA x FRB

Notes:

AL = Atherton Lake LC/MS/MS = Liquid Chromatography Mass Spectrometry

AOI = area of interest MS/MSD = matrix spike/ matrix spike duplicate

bgs = below ground surface NA = not applicable

CN = Camp Navajo QSM = Quality Systems Manual

ERB = equipment rinsate blank SB = soil boring

FD = field duplicate SD = sediment

FRB = field reagent blank SPG = spring

ft = feet SW = surface water

GW = groundwater TOC = total organic carbon

HSA = hollow stem auger USEPA = United States Environmental Protection Agency

Quality Control Samples

Groundwater Samples

Surface Water Samples

Sediment Samples

Spring Samples

AECOM 5-10
Table 5-2

Soil Boring Depths, Well Screen Intervals, and Groundwater Elevations

Site Inspection Report

Camp Navajo, Bellemont, Arizona

Area of 

Interest

Boring 

Location

Soil Boring Depth 

(feet bgs)

Well Screen 

Interval 

(feet bgs)

Top of Casing 

Elevation 

(feet NAVD88)

Depth to Water

(feet btoc)

Groundwate

Elevation

(feet NAVD88

AOI01-01 17 NA NA NA NAAOI01-02 17 NA NA NA NAAOI01-03 16 NA NA NA NAAOI01-04 1.7 NA NA NA NAAOI01-05 1.7 NA NA NA NAAOI02-01 40 NA NA NA NAAOI02-02 2 NA NA NA NAAOI02-03 2 NA NA NA NAAOI02-04 1 NA NA NA NA

AOI03-01 6 NA NA NA NA

AOI03-02 22 NA NA NA NAAOI03-03 25 NA NA NA NAAOI04-01 0.5 NA NA NA NAAOI04-02 2 NA NA NA NAAOI04-03 0.75 NA NA NA NAAOI04-04 0.75 NA NA NA NAAOI04-05 0.75 NA NA NA NAAOI04-06 2 NA NA NA NAAOI04-07 1 NA NA NA NAAOI04-08 2 NA NA NA NA

FLS-5 143 56.6-121.6 7108.85 90.53 7018.32

PMW-1 31.5 11.5-31.5 7068.05 30.29 7037.76

PMW-2 27.35 4.75-24.75 7068.71 25.41 7043.30

PMW-3 27.35 4.75-24.75 7067.09 DRY1 NA2

PMW-4 14.7 8.7-14.7 7067.71 14.41 7053.30PMW-5 16.8 11.8-16.8 7069.64 DRY1 NA2

AOI06-01 6 NA NA NA NAAOI06-02 0.75 NA NA NA NAAOI06-03 1.25 NA NA NA NA

SPG-01 NA NA NA NA NA

SPG-02 NA NA NA NA NA

SPG-03 NA NA NA NA NA

SPG-04 NA NA NA NA NA

SPG-05 NA NA NA NA NA

AL-01 0.2 NA NA NA NA

Notes:

1 During synoptic groundwater level measurements, well was found to be dry.2 Could not calculate groundwater measurement due to the well being dryAOI = area of interesAL = Atherton Lake

bgs = below ground surfacebtoc = below top of casingNA = not applicable

Sitewide

512346

NAVD88 = North American Vertical Datum 1988SPG = spring

AECOM 
AECOM 5-12

THIS PAGE INTENTIONALLY BLANK

Site Inspection Report

Camp Navajo, Bellemont, Arizona
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200 Area

Volunteer Wash

South Sink

Atherton Lake

Reservoir Number One

Building 2

Former Building 209

Former Building LR200

North Holding Pond

South Holding Pond

NAAD-40

Holding Pond

Reuse Site

AOI 2

AOI 3

AOI 1

AOI 5

AOI 4

AOI 6

AOI01-01

AOI01-02

AOI01-03 AOI01-04

AOI01-05

AOI02-01

AOI02-02 AOI02-03

AOI02-04

AOI03-01

AOI03-02

AOI03-03

AOI04-01

AOI04-02

AOI04-03

AOI04-04

AOI04-05

AOI04-06

AOI04-07

AOI04-08

AOI06-01

AOI06-02

AOI06-03

SPG-01

SPG-02

SPG-03

SPG-04

SPG-05

PMW-1

PMW-2

PMW-4

FSL-5

AL-01

Volunteer Wash

Exempt wells are typically used for potable purposes. Non-exempt wells typically provide higher volumes of water for irrigation or other purposes.

Proposed m Monitoring Wells were not installed due to bedrock refusal and lack of water-bearing units.

­ Figure 5-1

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Investigation at Camp Navajo, AZ

6/6/2023

6/6/2023

6/6/2023

MS

AB

CM

GIS BY

CHK BY

PM

Base Map: National Agricultural Imagery Program, 2017. Sources: Esri, HERE, Garmin,

USGS, Intermap, INCREMENT P, NRCan, Esri Japan, METI, Esri China (Hong Kong),

6/6/2023

1:15,480

"J Natural Spring

!? Soil Boring

!? Soil Boring/Monitoring Well

A! Existing Monitoring Well

"J Surface Water/Sediment

"S Surface Soil

Area of Interest

Potential Release Area

Facility Boundary

Water Body

Ephemeral/Intermitent Stream Site Inspection Sample Locations

12420 Milestone Center Drive

Germantown, MD 20876 0 645 1,290 2,580

Feet

AECOM 5-13
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Building 2

Former Building 209

North Holding Pond

South Holding Pond

AOI 3

AOI 1

AOI 6

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI01-05

AOI03-01

AOI03-02

AOI03-03

AOI06-01

AOI06-02

AOI06-03

­ Figure 5-2

CLIENT

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ARNG

Site Investigation at Camp Navajo, AZ

10/26/2022

10/26/2022

10/26/2022

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AB

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GIS BY

CHK BY

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Base Map: Sources: Esri, HERE, Garmin, USGS, Intermap, INCREMENT P, NRCan,

Esri Japan, METI, Esri China (Hong Kong), Esri Korea, Esri (Thailand), NGCC, (c)

10/26/2022

1:5,400

!? Soil Boring

!? Soil Boring/Monitoring Well

"S Surface Soil

Area of Interest

Potential Release Area

Facility Boundary

Ephemeral/Intermitent Stream

Site Insp ection Samp le Locations – AOI 1, AOI 3, AOI 6

12420 Milestone Center Drive

0 225 450 900 Germantown, MD 20876

Feet

Proposed Monitoring Wells were not installed due to bedrock refusal and lack of water-bearing units.

AECOM 5-14
!?

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!?

North Holding Pond

South Holding Pond

AOI 6

AOI06-01

AOI06-02

AOI06-03

0 225 450 900

Feet

­ Figure 5-2A

CLIENT

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ARNG

Site Investigation at Camp Navajo, AZ

9/7/2022

9/7/2022

9/7/2022

MS

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CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, USGS, Intermap, INCREMENT P, NRCan,

Esri Japan, METI, Esri China (Hong Kong), Esri Korea, Esri (Thailand), NGCC, (c)

9/7/2022

1:5,400

!? Soil Boring

!? Soil Boring/Monitoring Well

"S Surface Soil

Area of Interest

Potential Release Area

Facility Boundary

Site Inspection Sample Locations - 

AOI 1, AOI 3, and AOI 6 Zoom

12420 Milestone Center Drive

Germantown, MD 20876

!?

!?

!?

"S

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Former Building 209

AOI 1

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI01-05

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Building 2

AOI 3

AOI03-01

AOI03-02

AOI03-03

AECOM 5-15
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South Sink

Atherton Lake

Former Building LR200

Holding Ponds

Reuse Site

AOI 2

AOI 4

AOI02-01

AOI02-02 AOI02-03

AOI02-04

AOI04-01

AOI04-02

AOI04-03

AOI04-04

AOI04-05

AOI04-06

AOI04-07

AOI04-08

AL-01

­ Figure 5-3

CLIENT

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PROJECT

ARNG

Site Investigation at Camp Navajo, AZ

6/6/2023

6/6/2023

6/6/2023

MS

AB

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Base Map: National Agricultural Imagery Program, 2017. Sources: Esri, HERE, Garmin,

USGS, Intermap, INCREMENT P, NRCan, Esri Japan, METI, Esri China (Hong Kong),

6/6/2023

1:4,800

!? Soil Boring/Monitoring Well

"J Surface Water/Sediment

"S Surface Soil

Area of Interest

Potential Release Area

Facility Boundary

Water Body

Ephemeral/Intermitent Stream

Site Inspection Sample Locations - AOI 2, AOI 4

12420 Milestone Center Drive

0 200 400 800 Germantown, MD 20876

Feet

Proposed m Monitoring Wells were not installed due to bedrock refusal and lack of water-bearing units.

AECOM 5-16
A!

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A!

A!

Volunteer W ash

NAAD-40

AOI 5

PMW-1

PMW-2

PMW-4

FSL-5

­ Figure 5-4

CLIENT

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SCALE

PROJECT

ARNG

Site Investigation at Camp Navajo, AZ

10/26/2022

10/26/2022

10/26/2022

MS

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CM

GIS BY

CHK BY

PM

Base Map: National Agricultural Imagery Program, 2017. Sources: Esri, HERE, Garmin,

USGS, Intermap, INCREMENT P, NRCan, Esri Japan, METI, Esri China (Hong Kong),

10/26/2022

1:3,600

A! Existing Monitoring Well

Area of Interest

Potential Release Area

Facility Boundary

Water Body

Ephemeral/Intermitent Stream Site Inspection Sample Locations - AOI 5

12420 Milestone Center Drive 0 150 300 600 Germantown, MD 20876

Feet

Proposed Monitoring Wells were not installed due to bedrock refusal and lack of water-bearing uni

AECOM 5-17
AECOM 5-18

THIS PAGE INTENTIONALLY BLANK

Site Inspection Report

Camp Navajo, Bellemont, Arizona
Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 6-1

6. Site Inspection Results 

This section presents the analytical results of the SI. The SLs used in this evaluation are 

presented in Section 6.1. A discussion of the results for each AOI is provided in Section 6.3

through Section 6.9. Table 6-2 through Table 6-7 present results in soil, groundwater, surface

water, or sediment for the relevant compounds. Tables that contain all results are provided in 

Appendix F, and the laboratory reports are provided in Appendix G. 

6.1 Screening Levels 

The DoD has adopted a policy to retain facilities in the CERCLA process based on risk-based 

SLs for soil and groundwater, as described in a memorandum from the OSD dated 6 July 2022 

(Assistant Secretary of Defense, 2022). The ARNG program under which this SI was performed 

follows this DoD policy. Should the maximum site concentration for sampled media exceed the 

SLs established in the OSD memorandum, the AOI will proceed to the next phase under CERCLA. 

The SLs established in the OSD memorandum apply to the five compounds presented on Table 

6-1 below.

Table 6-1: Screening Levels (Soil and Groundwater)

Analyteb

Residential

(Soil)

(μg/kg)a 

0-2 feet bgs

Industrial/ 

Commercial 

Composite 

Worker

(Soil)

(μg/kg)a 

2-15 feet bgs

Tap Water

(Groundwater)

(ng/L)a

PFOA 19 250 6 

PFOS 13 160 4

PFBS 1,900 25,000 601 

PFHxS 130 1,600 39

PFNA 19 250 6 

Notes:

bgs = below ground surface; μg/kg = micrograms per kilogram; ng/L = nanograms per liter

a.) Assistant Secretary of Defense, 2022. Risk Based Screening Levels in Groundwater and Soil using United States Environmental Protection 

Agency’s (USEPA’s) Regional Screening Level Calculator. Hazard Quotient (HQ) = 0.1. 6 July 2022. 

b.) Of the six PFAS compounds presented in the 6 July 2022 OSD memorandum, HFPO-DA (commonly referred to as GenX) was not included 

as an analyte at the time of this SI. Based on the CSM developed during the PA and revised based on SI findings, the presence of HFPODA is not anticipated at the facility because HFPO-DA is generally not a component of MIL-SPEC AFFF and based on its history including 

distribution limitations that restricted use of GenX, it is generally not a component of other products the military used. In addition, it is 

unlikely that GenX would be an individual chemical of concern in the absence of other PFAS. 

The data in the subsequent sections are compared to the SLs presented in Table 6-1. The SLs 

for groundwater are based on direct ingestion. The SLs for soil are based on incidental ingestion 

and are applied to the depth intervals reasonably anticipated to be encountered by the receptors 

identified at the facility: the residential scenario is applied to surface soil results (0 to 2 feet bgs) 

and the industrial/commercial worker scenario is applied to shallow subsurface soil results (2 to 

15 feet bgs). The SLs are not applied to deep subsurface soil results (>15 feet bgs) because 15 

feet is the anticipated limit of construction activities. 
Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 6-2

6.2 Soil Physicochemical Analyses

To provide basic soil parameter information, soil samples were analyzed for TOC and pH, which

are important for evaluating transport through the soil medium. Appendix F contains the results 

of the TOC and pH sampling. 

The data collected in this investigation will be used in subsequent investigations, where 

appropriate, to assess fate and transport. According to the Interstate Technology Regulatory 

Council (ITRC), several important partitioning mechanisms include hydrophobic and lipophobic 

effects, electrostatic interactions, and interfacial behaviors. At relevant environmental pH values, 

certain PFAS are present as organic anions and are therefore relatively mobile in groundwater 

(Xiao et al., 2015), but tend to associate with the organic carbon fraction that may be present in 

soil or sediment (Higgins and Luthy, 2006; Guelfo and Higgins, 2013). When sufficient organic 

carbon is present, organic carbon normalized distribution coefficients (Koc values) can help in 

evaluating transport potential, though other geochemical factors (for example, pH and presence 

of polyvalent cations) may also affect PFAS sorption to solid phases (ITRC, 2018).

6.3 AOI 1 

This section presents the analytical results for soil and groundwater in comparison to SLs for 

AOI 1: Former Building 209. The soil and groundwater results are summarized on Table 6-2

through Table 6-5. Soil results are presented on Figure 6-1, Figure 6-3, Figure 6-5, Figure 6-7, 

and Figure 6-9 and groundwater results are presented on Figure 6-11 through Figure 6-16. 

6.3.1 AOI 1 Soil Analytical Results

Figure 6-1, Figure 6-3, Figure 6-5, Figure 6-7, and Figure 6-9 present the ranges of detections 

in soil. Table 6-2 through Table 6-4 summarize the soil results. 

Surface soil was sampled from (0 to 1.7 feet bgs or 0 to 2 feet bgs at boring locations AOI01-01 

through AOI01-05. Soil was also sampled from one or more shallow subsurface intervals at

AOI01-01 (13 to 15 feet bgs), AOI01-02 (8 to 10 feet bgs; 13 to 15 feet bgs), and AOI01-03 (3 to 

5 feet bgs; 8 to 10 feet bgs). PFOA, PFOS, PFHxS, PFNA, and PFBS were detected at 

concentrations below their SLs in surface soil. PFOA, PFOS, and PFNA were detected in three 

of the five locations with maximum concentrations of 0.413 J μg/kg, 6.35 μg/kg, and 0.070 J μg/kg, 

respectively. PFHxS and PFBS were detected at two of the five locations with maximum 

concentrations of 1.78 μg/kg and 0.061 J μg/kg, respectively.

PFOA was detected below the SL in shallow subsurface soil (8 to 10 feet bgs) at location AOI01-

02, with a concentration of 0.114 J μg/kg in the field duplicate sample (AOI01-02-8-10-D). PFOS, 

PFHxS, PFNA, and PFBS were not detected in shallow subsurface soil. 

6.3.2 AOI 1 Groundwater Analytical Results 

Figure 6-11 and Figure 6-12 present the ranges of detections in groundwater. Table 6-5 

summarizes the groundwater results. 

Groundwater was sampled from natural spring locations SPG-01 through SPG-05, which are fed 

by the perched aquifer underlying AOI 1. PFOS was detected above the SL of 4 nanograms per 

liter (ng/L) in four of the five spring locations, with concentrations ranging from 13.6 ng/L to 25.9

ng/L. PFOA, PFHxS, and PFBS were detected at concentrations below their SLs in groundwater. 

PFOA was detected at four of the five spring locations, with a maximum concentration of 1.70 J+ 

ng/L. PFHxS and PFBS were detected at all five spring locations with maximum concentrations 
AECOM 6-3

Site Inspection Report

Camp Navajo, Bellemont, Arizona

of 22.9 ng/L and 26.4 ng/L, respectively. PFNA was not detected in groundwater collected from

any of the five springs.

6.3.3 AOI 1 Conclusions

Based on the results of the SI, PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in soil 

below their SLs. PFOA was detected at concentrations above the SL in groundwater at spring 

locations fed by the perched aquifer underlying AOI 1. Based on the exceedances of the SL in 

groundwater within the perched aquifer, further evaluation at AOI 1 is warranted. 

6.4 AOI 2 

This section presents the analytical results for soil in comparison to SLs for AOI 2: Former Building 

LR200. Groundwater was not encountered in any of the borings drilled at AOI 2. The results in 

soil are presented in Table 6-2 through Table 6-4. Soil results are presented on Figure 6-2, 

Figure 6-4, Figure 6-6, Figure 6-8, and Figure 6-10. 

6.4.1 AOI 2 Soil Analytical Results 

Surface soil was sampled from 0 to 1 feet bgs or 0 to 2 feet bgs at boring locations AOI02-01

through AOI02-04. Soil was also sampled from two deep subsurface soil intervals (18 to 20 feet 

bgs; 33-35 feet bgs) at AOI02-01. PFOS, PFHxS, PFNA, and PFBS were each detected in at 

least one surface soil location at concentrations below their SLs with the following maximum 

concentrations: PFOS at 0.071 J μg/kg; PFHxS at 0.099 J μg/kg; PFNA at 0.037 J μg/kg; PFBS 

at 0.033 J μg/kg. PFOA was not detected in surface soil. PFOA, PFOS, PFHxS, PFNA, and PFBS 

were not detected in deep subsurface soil. 

6.4.2 AOI 2 Conclusions

Based on the results of the SI, PFOS, PFHxS, PFNA, and PFBS were detected at concentrations

below their SLs in surface soil. Therefore, further evaluation at AOI 2 is not warranted.

6.5 AOI 3 

This section presents the analytical results for soil and groundwater in comparison to SLs for 

AOI 3: Building 2. The soil and groundwater results are summarized on Table 6-2 through Table 

6-5. Soil results are presented on Figure 6-1, Figure 6-3, Figure 6-5, Figure 6-7, and Figure 6-

9 and groundwater results are presented on Figure 6-11 through Figure 6-12.

6.5.1 AOI 3 Soil Analytical Results 

Figure 6-1, Figure 6-3, Figure 6-5, Figure 6-7, and Figure 6-9 present the ranges of 

detections in soil. Table 6-2 through Table 6-4 summarize the soil results. 

Surface soil was sampled from 0 to 2.5 feet bgs and shallow subsurface soil collected from 3 to 

5 feet bgs at boring location AOI03-01. Soil was also sampled from surface soil (0 to 2 feet bgs), 

shallow subsurface soil (8 to 10 feet bgs), and deep subsurface soil (20 to 22 feet bgs and 23 to 

25 feet bgs, respectively) at AOI03-02 and AOI03-03. PFOS was detected above the SL of 13 

μg/kg in surface soil at AOI03-01, with a concentration of 41.6 μg/kg. The remaining four 

compounds were detected below their SLs in surface soil at AOI03-01, with concentrations as 

follows: PFOA at 4.56 μg/kg; PFHxS at 2.80 μg/kg; PFNA at 0.577 J μg/kg; and PFBS at 0.159 J 

μg/kg. 
Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 6-4

PFOA, PFOS, PFHxS, PFNA, and PFBS were detected at concentrations below their SLs in 

shallow subsurface soil. PFOS was detected at two of the three locations with a maximum 

concentration of 28.5 μg/kg. The remaining four compounds were detected at AOI03-01 with 

concentrations as follows: PFOA at 1.34 μg/kg; PFHxS at 1.77 μg/kg; PFNA at 0.240 J μg/kg; and 

PFBS at 0.133 J μg/kg.

PFOA, PFOS, PFHxS, PFNA, and PFBS were not detected in deep subsurface soil. 

6.5.2 AOI 3 Groundwater Analytical Results 

Figure 6-11 and Figure 6-12 present the ranges of detections in groundwater. Table 6-5 

summarizes the groundwater results. 

AOI 3 is underlain by the same perched aquifer as AOI 1 which feeds natural spring locations 

SPG-01 through SPG-05. The groundwater results from the spring samples are presented in 

Section 6.3.2. 

6.5.3 AOI 3 Conclusions

Based on the results of the SI, PFOS was detected at a concentration above the SL in surface 

soil. PFOA was detected at concentrations above the respective SL in groundwater at spring 

locations fed by the perched aquifer underlying AOI 3. Based on the exceedances of the SLs in

surface soil and groundwater within the perched aquifer, further evaluation at AOI 3 is warranted.

6.6 AOI 4 

This section presents the analytical results for soil in comparison to SLs for AOI 4: WWTP Holding 

Ponds and Effluent Reuse Site. Groundwater was not encountered in any of the borings drilled at 

AOI 4. The results in soil are presented in Table 6-2 through Table 6-4. Soil results are presented 

on Figure 6-2, Figure 6-4, Figure 6-6, Figure 6-8, and Figure 6-10. 

6.6.1 AOI 4 Soil Analytical Results

Surface soil was sampled from 0 to 2 feet bgs at boring locations AOI04-01 through AOI04-08. 

PFOA, PFOS, PFHxS, PFNA, and PFBS were detected at concentrations below their SLs in 

surface soil. PFOA, PFOS, and PFNA were detected in six of the eight locations, with maximum 

concentrations of 0.773 J μg/kg, 8.86 μg/kg, and 0.297 J μg/kg, respectively. PFHxS was detected 

at seven of the eight locations with a maximum concentration of 0.394 J μg/kg. PFBS was 

detected at four of the six locations with a maximum concentration of 0.079 J μg/kg.

6.6.2 AOI 4 Conclusions 

Based on the results of the SI, PFOA, PFOS, PFHxS, PFNA, and PFBS were detected at 

concentrations below their respective SLs in surface soil. Therefore, further evaluation at AOI 4 is 

not warranted.

6.7 AOI 5 

This section presents the analytical results for groundwater in comparison to SLs for AOI 5: 

NAAD-40. The results in groundwater are presented in Table 6-5. Groundwater results are 

presented on Figure 6-11 and Figure 6-12. 
AECOM 6-5

Site Inspection Report

Camp Navajo, Bellemont, Arizona

No soil was sampled at AOI 5, as NAAD-40 is a capped former sanitary landfill with land use 

restrictions preventing ground-disturbing activities to surface and subsurface soil. Furthermore, 

soil sampling would compromise the integrity of the landfill cap. 

6.7.1 AOI 5 Groundwater Analytical Results 

Groundwater was sampled from existing permanent monitoring wells FSL-5, PMW-1, and PMW2. PFOS and PFBS were detected at concentrations below their SLs in groundwater. PFOS was

detected at well location PMW-1, with a concentration of 2.60 J ng/L. PFBS was detected at well

locations PMW-1 and PMW-2, with concentrations of 5.06 ng/L and 1.27 J ng/L, respectively.

PFOA, PFHxS, and PFNA were not detected in groundwater.

It should be noted that the water collected from these monitoring wells was collected below the 

well screen (stagnant water) and are not low-flow samples representative of formation water. 

Under normal circumstances, these samples would not be used for decision making purposes; 

however, the samples were considered acceptable, for screening purposes only, to determine 

presence or absence of PFAS.

6.7.2 AOI 5 Conclusions 

Based on the results of the SI, PFOS and PFBS were detected in groundwater at concentrations 

below their respective SLs. However, there are concerns regarding the quality of the samples and 

representativeness of the results with respect to groundwater underlying the AOI. As a result, 

further evaluation of AOI 5 is warranted as a conservative measure. 

6.8 AOI 6 

This section presents the analytical results for soil and groundwater in comparison to SLs for 

AOI 6: North and South Holding Ponds. The soil and groundwater results are summarized on 

Table 6-2 through Table 6-5. Soil results are presented on and groundwater results are presented 

on Figure 6-1, Figure 6-3, Figure 6-5, Figure 6-7, and Figure 6-9. Figure 6-1 through Figure 

6-12.

6.8.1 AOI 6 Soil Analytical Results 

Figure 6-1, Figure 6-3, Figure 6-5, Figure 6-7, and Figure 6-9 present the ranges of detections 

in soil. Table 6-2 through Table 6-4 summarize the soil results. 

Surface soil was sampled from 0 to 2 feet bgs at boring locations AOI06-01 through AOI06-03. 

Soil was also sampled from the shallow subsurface (3 to 5 feet bgs) at AOI06-01. PFOS was 

detected above the SL of 13 μg/kg in surface soil at locations AOI06-01 and AOI06-03, with 

concentrations of 51.1 μg/kg and 15.9 μg/kg, respectively. The remaining four compounds were 

detected below their SLs in surface soil in at least one sample, with maximum concentrations as 

follows: PFOA at 14.4 μg/kg; PFHxS at 4.95 μg/kg; PFNA at 0.563 J μg/kg; and PFBS at 0.058 J 

μg/kg. 

PFOA, PFOS, PFHxS, and PFNA were detected at concentrations below their SLs in shallow 

subsurface soil at location AOI06-01, with concentrations as follows: PFOA at 3.06 μg/kg; PFOS 

at 37.5 μg/kg; PFHxS at 2.34 μg/kg; and PFNA at 0.458 J μg/kg. PFBS was not detected in 

shallow subsurface soil. 
Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 6-6

6.8.2 AOI 6 Groundwater Analytical Results 

Figure 6-11 and Figure 6-12 present the ranges of detections in groundwater. Table 6-5 

summarizes the groundwater results. 

AOI 6 is potentially underlain by the same perched aquifer as AOI 1 and AOI 3 that feeds natural 

spring locations SPG-01 through SPG-05. Groundwater results from the spring samples are

presented in Section 6.3.2. 

6.8.3 AOI 6 Conclusions 

Based on the results of the SI, PFOS was detected in surface soil above the SL. PFOA was 

detected at concentrations above the SL in groundwater at spring locations fed by the perched 

aquifer potentially underlying AOI 6. Based on the exceedances of the SLs in soil and groundwater 

within the perched aquifer, further evaluation at AOI 6 is warranted.

6.9 Atherton Lake

This section presents the analytical results for sediment and surface water for Atherton Lake. 

There are no established SLs for sediment and surface water; therefore, these results are 

presented for informational purposes only. The results in sediment and surface water are 

presented in Table 6-6 and Table 6-7, respectively. Sediment and surface water results are 

presented on Figure 6-13 through Figure 6-16. 

6.9.1 Atherton Lake Surface Water Analytical Results 

Surface water was sampled from one location (AL-01) along the shoreline of Atherton Lake. 

PFOA, PFOS, PFHxS, and PFBS were detected in surface water, with maximum concentrations 

in the field duplicate sample (AL-01-SW-D) as follows: PFOA at 7.22 ng/L; PFOS at 27.9 ng/L; 

PFHxS at 39 ng/L; and PFBS at 10.3 ng/L. PFNA was not detected in either the primary or 

duplicate surface water samples. Figure 6-13 and Figure 6-14 present the ranges of detections 

in surface water. Table 6-7 summarizes the surface water results. 

6.9.2 Atherton Lake Sediment Analytical Results

Sediment was sampled from one location (AL-01) along the shoreline of Atherton Lake. PFOS, 

PFHxS, and PFBS were detected in the sediment sample with concentrations of 0.518 J μg/kg, 

0.251 J μg/kg, and 0.044 J μg/kg, respectively. PFOA and PFNA were not detected. Figure 6-15

and Figure 6-16 present the ranges of detections in sediment. Table 6-6 summarizes the 

sediment results. 

6.9.3 Atherton Lake Conclusions

Based on the results of the SI, PFOS, PFHxS, and PFBS were detected in sediment at Atherton 

Lake. PFOA, PFOS, PFHxS, and PFBS were detected in surface water. There are no established 

SLs for sediment and surface water; therefore, these results are presented for informational 

purposes only. 
Table 6-2

PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Surface Soil

Site Inspection Report, Camp Navajo

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual

PFBS 1900 0.061 J ND U ND U 0.029 J ND U ND U ND U 0.032 J 0.033 J 0.159 J

PFHxS 130 1.78 ND U ND U ND U 0.106 J ND U ND U 0.056 J 0.099 J 2.80

PFNA 19 0.043 J ND U ND U 0.069 J 0.070 J ND U ND U ND U 0.037 J 0.577 J

PFOA 19 0.413 J ND U ND U 0.133 J 0.170 J ND U ND U ND U ND U 4.56

PFOS 13 2.88 ND U ND U 0.970 J 6.35 ND U 0.071 J ND U ND U 41.6

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AASF Army Aviation Support Facility

U = The analyte was not detected at a level greater than or equal to the adjusted DL AOI Area of Interest

UJ = The analyte was not detected at a level greater than or equal to the adjusted DL. However, the reported adjusted DL is approximate and may be inaccurate or imprecise. D duplicate

DL detection limit

ft feet

HQ hazard quotient

ID identification

LCMSMS liquid chromatography with tandem mass spectrometry

LOD limit of detection

ND analyte not detected above the LOD

OSD Office of the Secretary of Defense

QSM Quality Systems Manual

Qual interpreted qualifier

SB soil boring

USEPA United States Environmental Protection Agency

μg/kg micrograms per kilogram

Area of Interest

Sample ID

Sample Date

Depth

AOI01-01-SB-0-2

05/25/2021

0-2 ft

AOI01-02-SB-0-2

05/26/2021

0-2 ft

AOI01-03-SB-0-2

05/25/2021

0-2 ft 0-2 ft

AOI02-02-SB-0-2

05/28/2021

0-2 ft

AOI01-04-SB-0-1.7

05/26/2021

0-1.7 ft

AOI01-05-SB-0-1.7

05/26/2021

0-1.7 ft

a. Assistant Secretary of Defense, July 2022. Risk Based Screening Levels Calculated for PFOA, PFOS, PFBS, PFHxS, and PFNA in Groundwater or Soil using 

USEPA’s Regional Screening Level Calculator. HQ=0.1, May 2022. Soil screening levels based on residential scenario for incidental ingestion of contaminated soil.

AOI01 AOI02 AOI03

AOI03-01-SB-0-2.5

05/26/2021

0-2.5 ft

Soil, LCMSMS compliant with QSM 5.3 Table B-15 (μg/kg)

AOI02-03-SB-0-2

05/28/2021

0-2 ft

AOI02-04-SB-0-1

05/28/2021

0-1 ft

AOI02-01-SB-0-2

05/27/2021

AECOM 6-7
Table 6-2

PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Surface Soil

Site Inspection Report, Camp Navajo

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual

PFBS 1900 ND U ND U 0.036 J ND U 0.079 J ND U ND U 0.032 J ND U ND UJ

PFHxS 130 ND U ND U 0.087 J ND U 0.394 J 0.051 J 0.088 J 0.147 J 0.050 J 0.062 J

PFNA 19 ND U ND U 0.114 J ND U ND U 0.162 J 0.297 J 0.025 J 0.128 J 0.052 J

PFOA 19 ND U ND U 0.220 J ND U ND U 0.269 J 0.773 J 0.224 J 0.280 J ND UJ

PFOS 13 ND U ND U 1.71 0.199 J ND U 2.87 8.86 ND U 4.43 2.37 J

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AASF Army Aviation Support Facility

U = The analyte was not detected at a level greater than or equal to the adjusted DL AOI Area of Interest

UJ = The analyte was not detected at a level greater than or equal to the adjusted DL. However, the reported adjusted DL is approximate and may be inaccurate or imprecise. D duplicate

DL detection limit

ft feet

HQ hazard quotient

ID identification

LCMSMS liquid chromatography with tandem mass spectrometry

LOD limit of detection

ND analyte not detected above the LOD

OSD Office of the Secretary of Defense

QSM Quality Systems Manual

Qual interpreted qualifier

SB soil boring

USEPA United States Environmental Protection Agency

μg/kg micrograms per kilogram

Area of Interest

Sample ID

Sample Date

Depth

AOI03-02-SB-0-2

05/26/2021

0-2 ft

AOI03-03-SB-0-2

05/26/2021

0-2 ft

AOI04-01-SB-0-0.5

06/01/2021

0-0.5 ft

AOI04-05-SB-0-0.75

06/01/2021

0-0.75 ft

AOI04-02-SB-0-2

06/01/2021

0-2 ft

AOI04-03-SB-0-0.75

06/01/2021

0-0.75 ft

a. Assistant Secretary of Defense, July 2022. Risk Based Screening Levels Calculated for PFOA, PFOS, PFBS, PFHxS, and PFNA in Groundwater or Soil using 

USEPA’s Regional Screening Level Calculator. HQ=0.1, May 2022. Soil screening levels based on residential scenario for incidental ingestion of contaminated soil.

AOI03 AOI04

AOI04-08-SB-0-2

05/28/2021

0-2 ft

Soil, LCMSMS compliant with QSM 5.3 Table B-15 (μg/kg)

AOI04-06-SB-0-2

06/01/2021

0-2 ft

AOI04-07-SB-0-1

06/01/2021

0-1 ft

AOI04-04-SB-0-0.75

06/01/2021

0-0.75 ft

AECOM 6-8
Table 6-2

PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Surface Soil

Site Inspection Report, Camp Navajo

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual Result Qual

PFBS 1900 0.046 J ND U ND U ND U 0.058 J

PFHxS 130 0.358 J 4.95 ND U 0.038 J 1.60

PFNA 19 0.035 J 0.432 J 0.041 J 0.034 J 0.563 J

PFOA 19 0.103 J 14.4 ND U ND U 2.30

PFOS 13 1.44 J 51.1 ND U ND U 15.9

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AASF Army Aviation Support Facility

U = The analyte was not detected at a level greater than or equal to the adjusted DL AOI Area of Interest

UJ = The analyte was not detected at a level greater than or equal to the adjusted DL. However, the reported adjusted DL is approximate and may be inaccurate or imprecise. D duplicate

DL detection limit

ft feet

HQ hazard quotient

ID identification

LCMSMS liquid chromatography with tandem mass spectrometry

LOD limit of detection

ND analyte not detected above the LOD

OSD Office of the Secretary of Defense

QSM Quality Systems Manual

Qual interpreted qualifier

SB soil boring

USEPA United States Environmental Protection Agency

μg/kg micrograms per kilogram

Sample ID

Sample Date

Depth

AOI04

AOI04-08-SB-0-2-D

05/28/2021

0-2 ft

Soil, LCMSMS compliant with QSM 5.3 Table B-15 (μg/kg)

a. Assistant Secretary of Defense, July 2022. Risk Based Screening Levels Calculated for PFOA, PFOS, PFBS, PFHxS, and PFNA in Groundwater or Soil using 

USEPA’s Regional Screening Level Calculator. HQ=0.1, May 2022. Soil screening levels based on residential scenario for incidental ingestion of contaminated soil.

AOI06

AOI06-02-SB-0-0.75-D

05/27/2021

0-0.75 ft

AOI06-03-SB-0-1.25

05/27/2021

0-1.25 ft

AOI06-01-SB-0-2

05/27/2021

0-2 ft

AOI06-02-SB-0-0.75

05/27/2021

0-0.75 ft

Area of Interest

AECOM 6-9
Table 6-3

PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Shallow Subsurface Soil

Site Inspection Report, Camp Navajo

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Re

PFBS 25000 ND U ND U ND U ND U ND U ND U ND U 0.133 J ND PFHxS 1600 ND U ND U ND U ND U ND U ND U ND U 1.77 ND PFNA 250 ND U ND U ND U ND U ND U ND U ND U 0.240 J ND PFOA 250 ND U ND U ND UJ 0.114 J ND U ND U ND U 1.34 ND PFOS 160 ND U ND U ND U ND U ND U ND U ND U 28.5 ND 

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acidPFOA perfluorooctanoic acidPFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AOI Area of InterestU = The analyte was not detected at a level greater than or equal to the adjusted DL D duplicate

UJ = The analyte was not detected at a level greater than or equal to the adjusted DL. However, the reported adjusted DL is approximate and may be inaccurate or imprecise. DL detection limit

ft feetHQ hazard quotientID identificationLCMSMS liquid chromatography with tandem LOD limit of detectionND analyte not detected above the LODOSD Office of the Secretary of DefenseQSM Quality Systems ManualQual interpreted qualifierSB soil boringUSEPA United States Environmental Protecμg/kg micrograms per kilogram

Area of Interest

Sample ID

Sample Date

Depth

AOI01-01-SB-13-15

05/25/2021

13-15 ft

AOI01-01-SB-13-15-D

05/25/2021

13-15 ft

AOI01-02-SB-8-10

05/26/2021

8-10 ft

AOI01-03-SB-8-10

05/25/2021

8-10 ft

AOI01-02-SB-8-10-D

05/26/2021

8-10 ft

AOI01-02-SB-13-15

05/26/2021

13-15 ft

a. Assistant Secretary of Defense, July 2022. Risk Based Screening Levels Calculated for PFOA, PFOS, PFBS, PFHxS, and PFNA in Groundwater or Soil using USEPA’s Regional Screening Level Calculator. HQ=0.1, May 2022. Soil screening levels based on industrial/commercial composite worker scenario for incidental ingestion of contaminated soil.

AOI01 

Soil, LCMSMS compliant with QSM 5.3 Table B-15 (μg/kg)

AOI03-01-SB-3-5

05/26/2021

3-5 ft

AO

AOI01-03-SB-3-5

05/25/2021

3-5 ft

AECOM 
Table 6-3

PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Shallow Subsurface Soil

Site Inspection Report, Camp Navajo

Analyte OSD Screening 

Level a

Result Qual

PFBS 25000 ND UPFHxS 1600 2.34PFNA 250 0.458 JPFOA 250 3.06PFOS 160 37.5

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acidPFOA perfluorooctanoic acidPFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AOI Area of InterestU = The analyte was not detected at a level greater than or equal to the adjusted DL D duplicate

UJ = The analyte was not detected at a level greater than or equal to the adjusted DL. However, the reported adjusted DL is approximate and may be inaccurate or imprecise. DL detection limit

ft feetHQ hazard quotientID identificationLCMSMS liquid chromatography with tandem LOD limit of detectionND analyte not detected above the LODOSD Office of the Secretary of DefenseQSM Quality Systems ManualQual interpreted qualifierSB soil boringUSEPA United States Environmental Protecμg/kg micrograms per kilogram

Soil, LCMSMS compliant with QSM 5.3 Table B-15 (μg/kg)

a. Assistant Secretary of Defense, July 2022. Risk Based Screening Levels Calculated for PFOA, PFOS, PFBS, PFHxS, and PFNA in Groundwater or Soil using USEPA’s Regional Screening Level Calculator. HQ=0.1, May 2022. Soil screening levels based on industrial/commercial composite worker scenario for incidental ingestion of contaminated soil.

Area of Interest

Sample ID

Sample Date

Depth

AOI06

AOI06-01-SB-3-5

05/27/2021

3-5 ft

AECOM 
Table 6-4

PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Deep Subsurface Soil

Site Inspection Report, Camp Navajo

Area of Interest

Sample ID

Sample Date

Depth

Analyte Result Qual Result Qual Result Qual Result Qual

PFBS ND U ND U ND U ND UPFHxS ND U ND U ND U ND UPFNA ND U ND U ND U ND UPFOA ND U ND U ND U ND UPFOS ND U ND U ND U ND U

Interpreted Qualifiers Chemical AbbreviationsU = The analyte was not detected at a level greater than or equal to the adjusted DL PFBS perfluorobutanesulfonic acid

PFHxS perfluorohexanesulfonic acidPFNA perfluorononanoic acidPFOA perfluorooctanoic acidPFOS perfluorooctanesulfonic acidAcronyms and Abbreviations

AOI Area of InterestDL detection limitft feetID identificationLCMSMS liquid chromatography with tandem mass LOD limit of detectionND analyte not detected above the LODQSM Quality Systems ManualQual interpreted qualifierSB soil boringμg/kg micrograms per kilogram

Soil, LCMSMS compliant with QSM 5.3 Table B-15 (μg/kg)

AOI02 AOI03

AOI03-02-SB-20-22

05/26/2021

20-22 ft

AOI03-03-SB-23-25

05/26/2021

23-25 ft

AOI02-01-SB-18-20

05/27/2021

18-20 ft

AOI02-01-SB-33-35

05/27/2021

33-35 ft

AECOM 
Table 6-5

PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Groundwater

Site Inspection Report, Camp Navajo

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Re

PFBS 601 4.24 13.1 24.5 J+ 26.4 12.8 ND U ND U 5.06 1.27 PFHxS 39 16.7 22.9 17.2 J+ 21.5 1.48 J ND U ND U ND U ND PFNA 6 ND U ND U ND UJ ND U ND U ND U ND U ND U ND PFOA 6 1.16 J 1.69 J 1.70 J+ 1.48 J ND U ND U ND U ND U ND PFOS 4 13.6 24.3 19.4 J+ 25.9 1.19 J ND U ND U 2.60 J ND 

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acidPFOA perfluorooctanoic acidPFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AOI Area of InterestJ+ = Estimated concentration, biased high D duplicate

U = The analyte was not detected at a level greater than or equal to the adjusted DL DL detection limitUJ = The analyte was not detected at a level greater than or equal to the adjusted DL. However, the reported adjusted DL is approximate and may be inaccurate or imprecise. GW groundwater

HQ hazard quotientID identificationLCMSMS liquid chromatography with tandem LOD limit of detectionND analyte not detected above the LODOSD Office of the Secretary of DefenseQSM Quality Systems ManualQual interpreted qualifierUSEPA United States Environmental Protecng/l nanogram per liter

SPG-02-GW

06/02/2021

SPG-03-GW

06/02/2021

Area of Interest

Sample ID

Sample Date

SPG-01-GW

06/02/2021

Water, LCMSMS compliant with QSM 5.3 Table B-15 (ng/l)

a. Assistant Secretary of Defense, July 2022. Risk Based Screening Levels Calculated for PFOA, PFOS, PFBS, PFHxS, and PFNA in Groundwater or Soil using USEPA’s Regional Screening Level Calculator. HQ=0.1, May 2022 Groundwater screening levels based on residential scenario for direct ingestion of groundwater.

AOI01 AOI05

PMW-1-060221

06/02/2021

PM

FSL-5-060121

06/01/2021

FSL-5-060121-D

06/01/2021

SPG-04-GW

06/02/2021

SPG-05-GW

06/02/2021

AECOM 
Table 6-5

PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Groundwater

Site Inspection Report, Camp Navajo

Analyte OSD Screening 

Level a

Result Qual

PFBS 601 ND UPFHxS 39 ND UPFNA 6 ND UPFOA 6 ND UPFOS 4 ND U

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acidPFOA perfluorooctanoic acidPFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AOI Area of InterestJ+ = Estimated concentration, biased high D duplicate

U = The analyte was not detected at a level greater than or equal to the adjusted DL DL detection limitUJ = The analyte was not detected at a level greater than or equal to the adjusted DL. However, the reported adjusted DL is approximate and may be inaccurate or imprecise. GW groundwater

HQ hazard quotientID identificationLCMSMS liquid chromatography with tandem LOD limit of detectionND analyte not detected above the LODOSD Office of the Secretary of DefenseQSM Quality Systems ManualQual interpreted qualifierUSEPA United States Environmental Protecng/l nanogram per liter

Water, LCMSMS compliant with QSM 5.3 Table B-15 (ng/l)

a. Assistant Secretary of Defense, July 2022. Risk Based Screening Levels Calculated for PFOA, PFOS, PFBS, PFHxS, and PFNA in Groundwater or Soil using USEPA’s Regional Screening Level Calculator. HQ=0.1, May 2022 Groundwater screening levels based on residential scenario for direct ingestion of groundwater.

Area of Interest

Sample ID

Sample Date

AOI05

PMW-4-060221

06/02/2021

AECOM 
Table 6-6

PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Sediment

Site Inspection Report, Camp Navajo

Area of Interest

Sample ID

Sample Date

Depth

Analyte Result Qual Result Qual

PFBS 0.044 J ND UJPFHxS 0.251 J 0.063 JPFNA ND U ND UJPFOA ND U ND UJPFOS 0.518 J 0.163 J

Interpreted Qualifiers Chemical AbbreviationsJ = Estimated concentration PFBS perfluorobutanesulfonic acidU = The analyte was not detected at a level greater than or equal to the adjusted DL PFHxS perfluorohexanesulfonic acidUJ = The analyte was not detected at a level greater than or equal to the adjusted DL. However, the reported adjusted DL is approximate and may be inaccurate or imprecise. PFNA perfluorononanoic acid

PFOA perfluorooctanoic acidPFOS perfluorooctanesulfonic acidAcronyms and Abbreviations

AOI Area of InterestD duplicateDL detection limitft feetID identificationLCMSMS liquid chromatography with tandem mass LOD limit of detectionND analyte not detected above the LODQSM Quality Systems ManualQual interpreted qualifierSD sedimentμg/kg micrograms per kilogram

Sediment, LCMSMS compliant with QSM 5.3 Table B-15 (μg/kg)

AL-01

AL-01-SD-0-0.2

06/01/2021

0-0.2 ft

AL-01-SD-0-0.2-D

06/01/2021

0-0.2 ft

AECOM 
Table 6-7

PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Surface Water

Site Inspection Report, Camp Navajo

Area of Interest

Sample ID

Sample Date

Analyte Result Qual Result Qual

PFBS 9.49 10.3

PFHxS 36.2 39.0

PFNA ND U ND UPFOA 7.04 7.22

PFOS 21.2 27.9

Interpreted Qualifiers Chemical AbbreviationsU = The analyte was not detected at a level greater than or equal to the adjusted DL PFBS perfluorobutanesulfonic acid

PFHxS perfluorohexanesulfonic acidPFNA perfluorononanoic acidPFOA perfluorooctanoic acidPFOS perfluorooctanesulfonic acidAcronyms and Abbreviations

AASF Army Aviation Support FacilityAOI Area of InterestD duplicateDL detection limitID identificationLCMSMS liquid chromatography with tandem mass LOD limit of detectionND analyte not detected above the LODQSM Quality Systems ManualQual interpreted qualifierng/l nanogram per literSW surface water

Water, LCMSMS compliant with QSM 5.3 Table B-15 (ng/l)

AL-01

AL-01-SW

06/01/2021

AL-01-SW-D

06/01/2021

AECOM 
AOI01-01

AOI01-02

AOI01-03 AOI01-04

AOI01-05

AOI03-01

AOI03-02

AOI03-03

AOI06-01

AOI06-02

AOI06-03

AOI01-01

AOI01-02

AOI01-03

AOI03-01

AOI03-02

AOI03-03

AOI06-01

AOI01-02 AOI01-03

AOI03-02

AOI03-03

12420 Milestone Center Drive

Germantown, MD 20876 Figure 6-1

PFOA Detections in Soil - 

AOI 1, AOI 3, AOI 6

9/12/2022

9/12/2022

MS 9/12/2022

AB

CM

GIS BY

CHK BY

PM

9/12/2022

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Investigation at Camp Navajo, AZ

Base Map: Sources: Esri, HERE, Garmin, USGS, Intermap,

INCREMENT P, NRCan, Esri Japan, METI, Esri China (Hong

1:8,040

Shallow

Intermediate

Deep

Facility Boundary

Ephemeral/Intermitent Stream

0 335 670 1,340

­

Feet

PFOA Results (μg/Kg)

ND

>ND - 19

>19 - 250

>250 - 2,500

>2,500

Exceedances of the OSD SL are depicted with a yellow halo.

Depth intervals shown represent respective sampling position within a given soil boring location.

AECOM 6-17
South Sink

Atherton Lake

AOI02-01

AOI02-02 AOI02-03

AOI02-04

AOI04-01

AOI04-02

AOI04-03

AOI04-04

AOI04-05

AOI04-06

AOI04-07

AOI04-08

South Sink

Atherton Lake

AOI02-01

South Sink

Atherton Lake

AOI02-01

12420 Milestone Center Drive

Germantown, MD 20876 Figure 6-2

PFOA Detections in Soil - 

AOI 2 and AOI 4

9/12/2022

9/12/2022

MS 9/12/2022

AB

CM

GIS BY

CHK BY

PM

9/12/2022

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Investigation at Camp Navajo, AZ

Base Map: Sources: Esri, HERE, Garmin, USGS, Intermap,

INCREMENT P, NRCan, Esri Japan, METI, Esri China (Hong

1:6,600

Shallow

Intermediate

Deep

0 275 550 1,100

­

Feet

Facility Boundary

Water Body

Ephemeral/Intermitent Stream

PFOA Results (μg/Kg)

ND

>ND - 19

>19 - 250

>250 - 2,500

>2,500

Exceedances of the OSD SL are depicted with a yellow halo.

Depth intervals shown represent respective sampling position within a given soil boring location.

AECOM 6-18
AOI01-01

AOI01-02

AOI01-03 AOI01-04

AOI01-05

AOI03-01

AOI03-02

AOI03-03

AOI06-01

AOI06-02

AOI06-03

AOI01-01

AOI01-02

AOI01-03

AOI03-01

AOI03-02

AOI03-03

AOI06-01

AOI01-02 AOI01-03

AOI03-02

AOI03-03

12420 Milestone Center Drive

Germantown, MD 20876 Figure 6-3

PFOS Detections in Soil - 

AOI 1, AOI 3, AOI 6

9/12/2022

9/12/2022

MS 9/12/2022

AB

CM

GIS BY

CHK BY

PM

9/12/2022

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Investigation at Camp Navajo, AZ

Base Map: Sources: Esri, HERE, Garmin, USGS, Intermap,

INCREMENT P, NRCan, Esri Japan, METI, Esri China (Hong

1:8,040

Facility Boundary

Ephemeral/Intermitent Stream

Shallow

Intermediate

Deep

PFOS Results (μg/Kg)

ND

>ND - 13

>13 - 160

>160 - 1,600

>1,600

0 335 670 1,340

­

Feet

Exceedances of the OSD SL are depicted with a yellow halo.

Depth intervals shown represent respective sampling position within a given soil boring location.

AECOM 6-19
South Sink

Atherton Lake

AOI02-01

AOI02-02 AOI02-03

AOI02-04

AOI04-01

AOI04-02

AOI04-03

AOI04-04

AOI04-05

AOI04-06

AOI04-07

AOI04-08

South Sink

Atherton Lake

AOI02-01

South Sink

Atherton Lake

AOI02-01

12420 Milestone Center Drive

Germantown, MD 20876 Figure 6-4

PFOS Detections in Soil - 

AOI 2 and AOI 4

9/12/2022

9/12/2022

MS 9/12/2022

AB

CM

GIS BY

CHK BY

PM

9/12/2022

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Investigation at Camp Navajo, AZ

Base Map: Sources: Esri, HERE, Garmin, USGS, Intermap,

INCREMENT P, NRCan, Esri Japan, METI, Esri China (Hong

1:6,600

Facility Boundary

Water Body

Ephemeral/Intermitent Stream

Shallow

Intermediate

Deep

PFOS Results (μg/Kg)

ND

>ND - 13

>13 - 160

>160 - 1,600

>1,600

0 275 550 1,100

­

Feet

Exceedances of the OSD SL are depicted with a yellow halo.

Depth intervals shown represent respective sampling position within a given soil boring location.

AECOM 6-20
AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI01-05

AOI03-01

AOI03-02

AOI03-03

AOI06-01

AOI06-02

AOI06-03

AOI01-01

AOI01-02

AOI01-03

AOI03-01

AOI03-02

AOI03-03

AOI06-01

AOI01-02 AOI01-03

AOI03-02

AOI03-03

Shallow

Intermediate

Deep

12420 Milestone Center Drive

Germantown, MD 20876 Figure 6-5

PFBS Detections in Soil - 

AOI 1, AOI 3, AOI 6

9/12/2022

9/12/2022

MS 9/12/2022

AB

CM

GIS BY

CHK BY

PM

9/12/2022

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Investigation at Camp Navajo, AZ

Base Map: Sources: Esri, HERE, Garmin, USGS, Intermap,

INCREMENT P, NRCan, Esri Japan, METI, Esri China (Hong

1:8,040

Facility Boundary

Ephemeral/Intermitent Stream

0 335 670 1,340

­

Feet

PFBS Results (μg/Kg)

ND

>ND - 10

>10 - 1,900

>1,900 - 25,000

>25,000

Exceedances of the OSD SL are depicted with a yellow halo.

Depth intervals shown represent respective sampling position within a given soil boring location.

AECOM 6-21
South Sink

Atherton Lake

AOI02-01

AOI02-02 AOI02-03

AOI02-04

AOI04-01

AOI04-02

AOI04-03

AOI04-04

AOI04-05

AOI04-06

AOI04-07

AOI04-08

South Sink

Atherton Lake

AOI02-01

South Sink

Atherton Lake

AOI02-01

12420 Milestone Center Drive

Germantown, MD 20876 Figure 6-6

PFBS Detections in Soil - 

AOI 2 and AOI 4

9/12/2022

9/12/2022

MS 9/12/2022

AB

CM

GIS BY

CHK BY

PM

9/12/2022

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Investigation at Camp Navajo, AZ

Base Map: Sources: Esri, HERE, Garmin, USGS, Intermap,

INCREMENT P, NRCan, Esri Japan, METI, Esri China (Hong

1:6,600

Facility Boundary

Water Body

Ephemeral/Intermitent Stream

Shallow

Intermediate

Deep

0 275 550 1,100

­

Feet

PFBS Results (μg/Kg)

ND

>ND - 10

>10 - 1,900

>1,900 - 25,000

>25,000

Exceedances of the OSD SL are depicted with a yellow halo.

Depth intervals shown represent respective sampling position within a given soil boring location.

AECOM 6-22
AOI01-01

AOI01-02

AOI01-03 AOI01-04

AOI01-05

AOI03-01

AOI03-02

AOI03-03

AOI06-01

AOI06-02

AOI06-03

AOI01-01

AOI01-02

AOI01-03

AOI03-01

AOI03-02

AOI03-03

AOI06-01

AOI01-02 AOI01-03

AOI03-02

AOI03-03

Shallow

Intermediate

Deep

12420 Milestone Center Drive

Germantown, MD 20876 Figure 6-7

PFHxS Detections in Soil - 

AOI 1, AOI 3, AOI 6

9/12/2022

9/12/2022

MS 9/12/2022

AB

CM

GIS BY

CHK BY

PM

9/12/2022

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Investigation at Camp Navajo, AZ

Base Map: Sources: Esri, HERE, Garmin, USGS, Intermap,

INCREMENT P, NRCan, Esri Japan, METI, Esri China (Hong

1:8,040

Facility Boundary

Ephemeral/Intermitent Stream

0 335 670 1,340

­

Feet

PFHxS Results (μg/Kg)

ND

>ND - 10

>10 - 130

>130 - 1,600

>1,600

Exceedances of the OSD SL are depicted with a yellow halo.

Depth intervals shown represent respective sampling position within a given soil boring location.

AECOM 6-23
South Sink

Atherton Lake

AOI02-01

AOI02-02 AOI02-03

AOI02-04

AOI04-01

AOI04-02

AOI04-03

AOI04-04

AOI04-05

AOI04-06

AOI04-07

AOI04-08

South Sink

Atherton Lake

AOI02-01

South Sink

Atherton Lake

AOI02-01

12420 Milestone Center Drive

Germantown, MD 20876 Figure 6-8

PFHxS Detections in Soil - 

AOI 2 and AOI 4

9/12/2022

9/12/2022

MS 9/12/2022

AB

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9/12/2022

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ARNG

Site Investigation at Camp Navajo, AZ

Base Map: Sources: Esri, HERE, Garmin, USGS, Intermap,

INCREMENT P, NRCan, Esri Japan, METI, Esri China (Hong

1:6,600

Facility Boundary

Water Body

Ephemeral/Intermitent Stream

Shallow

Intermediate

Deep

0 275 550 1,100

­

Feet

PFHxS Results (μg/Kg)

ND

>ND - 10

>10 - 130

>130 - 1,600

>1,600

Exceedances of the OSD SL are depicted with a yellow halo.

Depth intervals shown represent respective sampling position within a given soil boring location.

AECOM 6-24
AOI01-01

AOI01-02

AOI01-03 AOI01-04

AOI01-05

AOI03-01

AOI03-02

AOI03-03

AOI06-01

AOI06-02

AOI06-03

AOI01-01

AOI01-02

AOI01-03

AOI03-01

AOI03-02

AOI03-03

AOI06-01

AOI01-02 AOI01-03

AOI03-02

AOI03-03

Shallow

Intermediate

Deep

12420 Milestone Center Drive

Germantown, MD 20876 Figure 6-9

PFNA Detections in Soil - 

AOI 1, AOI 3, AOI 6

9/12/2022

9/12/2022

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ARNG

Site Investigation at Camp Navajo, AZ

Base Map: Sources: Esri, HERE, Garmin, USGS, Intermap,

INCREMENT P, NRCan, Esri Japan, METI, Esri China (Hong

1:8,040

Facility Boundary

Ephemeral/Intermitent Stream

0 335 670 1,340

­

Feet

PFNA Results (μg/Kg)

ND

>ND - 19

>19 - 250

>250 - 2,500

>2,500

Exceedances of the OSD SL are depicted with a yellow halo.

Depth intervals shown represent respective sampling position within a given soil boring location.

AECOM 6-25
South Sink

Atherton Lake

AOI02-01

AOI02-02 AOI02-03

AOI02-04

AOI04-01

AOI04-02

AOI04-03

AOI04-04

AOI04-05

AOI04-06

AOI04-07

AOI04-08

South Sink

Atherton Lake

AOI02-01

South Sink

Atherton Lake

AOI02-01

12420 Milestone Center Drive

Germantown, MD 20876 Figure 6-10

PFNA Detections in Soil - 

AOI 2 and AOI 4

9/12/2022

9/12/2022

MS 9/12/2022

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ARNG

Site Investigation at Camp Navajo, AZ

Base Map: Sources: Esri, HERE, Garmin, USGS, Intermap,

INCREMENT P, NRCan, Esri Japan, METI, Esri China (Hong

1:6,600

Facility Boundary

Water Body

Ephemeral/Intermitent Stream

Shallow

Intermediate

Deep

0 275 550 1,100

­

Feet

PFNA Results (μg/Kg)

ND

>ND - 19

>19 - 250

>250 - 2,500

>2,500

Exceedances of the OSD SL are depicted with a yellow halo.

Depth intervals shown represent respective sampling position within a given soil boring location.

AECOM 6-26
Volunteer Wash

Atherton Lake

Reservoir Number One

Vo lunteer W as h

SPG-01

SPG-02

SPG-03

SPG-04

SPG-05

PMW-1

PMW-2

PMW-4

FSL-5

Volunteer Wash

Atherton Lake

Reservoir Number One

Vo lunteer W as h

SPG-01

SPG-02

SPG-03

SPG-04

SPG-05

PMW-1

PMW-2

PMW-4

FSL-5

Volunteer Wash

Atherton Lake

Reservoir Number One

Vo lunteer W as h

SPG-01

SPG-02

SPG-03

SPG-04

SPG-05

PMW-1

PMW-2

PMW-4

FSL-5

12420 Milestone Center Drive

Germantown, MD 20876 Figure 6-11

PFOA, PFOS, and PFBS Detections

in Groundwater

10/26/2022

10/26/2022

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ARNG

Site Investigation at Camp Navajo, AZ

Base Map: Sources: Esri, HERE, Garmin, USGS, Intermap,

INCREMENT P, NRCan, Esri Japan, METI, Esri China (Hong

1:16,200

Legend

Facility Boundary

Water Body

Ephemeral/Intermitent Stream

Inferred Shallow Groundwater Flow Direction

Inferred Groundwater Flow Direction

PFOA

PFOS

PFBS

PFOA Results (ng/L)

ND

>ND - 6

>6 - 40

>40 - 70

>70

PFOS Results (ng/L)

ND

>ND - 4

>4 - 40

>40 - 70

>70

PFBS Results (ng/L)

ND

>ND - 100

>100 - 601

>601 - 2,000

>2,000

0 675 1,350 2,700

­

Feet

Exceedances of the OSD SL are depicted with a yellow halo.

AECOM 6-27
Volunteer Wash

South Sink

Atherton Lake

Reservoir Number One

Vol unteer W ash

SPG-01

SPG-02

SPG-03

SPG-04

SPG-05

PMW-1

PMW-2

PMW-4

FSL-5

Volunteer Wash

South Sink

Atherton Lake

Reservoir Number One

Vol unteer W ash

SPG-01

SPG-02

SPG-03

SPG-04

SPG-05

PMW-1

PMW-2

PMW-4

FSL-5

12420 Milestone Center Drive

Germantown, MD 20876 Figure 6-12

PFHxS and PFNA Detections

in Groundwater

10/26/2022

10/26/2022

MS 10/26/2022

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10/26/2022

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PROJECT

ARNG

Site Investigation at Camp Navajo, AZ

Exceedances of the OSD SL are depicted with a yellow halo.

Base Map: Sources: Esri, HERE, Garmin, USGS, Intermap,

INCREMENT P, NRCan, Esri Japan, METI, Esri China (Hong

1:16,200

0 675 1,350 2,700

Feet

Legend

Facility Boundary

Water Body

Ephemeral/Intermitent Stream

Inferred Shallow Groundwater Flow Direction

Inferred Groundwater Flow Direction

PFHxS

PFNA

PFHxS Resutls (ng/L)

ND

>ND - 39

>39 - 100

>100 - 1,000

>1,000

PFNA Results (ng/L)

ND

>ND - 6

>6 - 100

>100 - 1,000

>1,000

­

AECOM 6-28
South Sink

Atherton Lake

AL-01

South Sink

Atherton Lake

AL-01

PFOAPFOS

PFBS

PFOA Results (ng/L)

ND>ND - 6>6 - 40>40 - 70>70

PFOS Results (ng/L)

ND>ND - 4>4 - 40>40 - 70>70
South Sink

Atherton Lake

AL-01

South Sink

Atherton Lake

AL-01

12420 Milestone Center Drive

Germantown, MD 20876 Figure 6-14

PFHxS and PFNA Detections

in Surface Water

9/7/2022

9/7/2022

MS 9/7/2022

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9/7/2022

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ARNG

Site Investigation at Camp Navajo, AZ

Base Map: Sources: Esri, HERE, Garmin, USGS, Intermap,

INCREMENT P, NRCan, Esri Japan, METI, Esri China (Hong

1:6,600

0 275 550 1,100

Feet

Legend

Facility Boundary

Water Body

Ephemeral/Intermitent Stream

Surface Water Flow Direction

PFHxS

PFNA

PFHxS Results (ng/L)

ND

>ND - 39

>39 - 100

>100 - 1,000

>1,000

PFNA Results (ng/L)

ND

>ND - 6

>6 - 100

>100 - 1,000

>1,000

­

AECOM 6-30
South Sink

Atherton Lake

AL-01

South Sink

Atherton Lake

AL-01

South Sink

Atherton Lake

AL-01

12420 Milestone Center Drive

Germantown, MD 20876 Figure 6-15

PFOA, PFOS, and PFBS Detections

 in Sediment

9/7/2022

9/7/2022

MS 9/7/2022

AB

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9/7/2022

CLIENT

REVISED

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PROJECT

ARNG

Site Investigation at Camp Navajo, AZ

Base Map: Sources: Esri, HERE, Garmin, USGS, Intermap,

INCREMENT P, NRCan, Esri Japan, METI, Esri China (Hong

1:6,600

0 275 550 1,100

Feet

Legend

Facility Boundary

Water Body

Ephemeral/Intermitent Stream

PFOA

PFOS

PFBS

PFOA Results (μg/Kg)

ND

>ND - 19

>19 - 250

>250 - 2,500

>2,500

PFOS Results (μg/Kg)

ND

>ND - 13

>13 - 160

>160 - 1,600

>1,600

PFBS Results (μg/Kg)

ND

>ND - 10

>10 - 1,900

>1,900 - 25,000

>25,000

­

AECOM 6-31
South Sink

Atherton Lake

AL-01

South Sink

Atherton Lake

AL-01

12420 Milestone Center Drive

Germantown, MD 20876 Figure 6-16

PFHxS and PFNA Detections

 in Sediment

9/7/2022

9/7/2022

MS 9/7/2022

AB

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9/7/2022

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Investigation at Camp Navajo, AZ

Base Map: Sources: Esri, HERE, Garmin, USGS, Intermap,

INCREMENT P, NRCan, Esri Japan, METI, Esri China (Hong

1:6,600

0 275 550 1,100

Feet

Legend

Facility Boundary

Water Body

Ephemeral/Intermitent Stream

PFHxS

PFNA

PFHxS Resultsg (μg/Kg)

ND

>ND - 10

>10 - 130

>130 - 1,600

>1,600

PFNA Results (μg/Kg)

ND

>ND - 19

>19 - 250

>250 - 2,500

>2,500

­

AECOM 6-32
Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 7-1

7. Exposure Pathways

The CSMs for each AOI, revised based on the SI findings, are presented on Figure 7-1 through 

Figure 7-6. Please note that while the CSM discussion assists in determining if a receptor may 

be impacted, the decision to move from SI to RI or interim action is determined based upon 

exceedances of the SLs for the relevant compounds and whether the release is more than likely 

attributable to the DoD. A CSM presents the current understanding of the site conditions with 

respect to known and suspected sources, potential transport mechanisms and migration 

pathways, and potentially exposed human receptors. A human exposure pathway is considered 

potentially complete when the following conditions are present:

1. Contaminant source;

2. Environmental fate and transport;

3. Exposure point;

4. Exposure route; and

5. Potentially exposed populations.

If any of these elements are missing, the pathway is incomplete. The CSM figures use an empty 

circle symbol to represent an incomplete exposure pathway. Areas with an incomplete pathway 

generally warrant no further action. However, the pathway is considered potentially complete if the 

relevant compounds are detected, in which case the CSM figure uses a half-filled circle symbol to 

represent a potentially complete exposure pathway. Additionally, a completely filled circle symbol is 

used to indicate when a potentially complete exposure pathway has detections of relevant 

compounds above the SLs. Areas with an identified potentially complete pathway that have 

detections of the relevant compounds above the SLs may warrant further investigation. Although 

the CSMs indicate whether potentially complete exposure pathways may exist, the 

recommendation for future study in an RI or no action at this time is based on the comparison of 

the SI analytical results for the relevant compounds to the SLs.

In general, the potential routes of exposure to the relevant compounds are ingestion and 

inhalation. Human exposure via the dermal contact pathway may occur, and current risk practice 

suggests it is an insignificant pathway compared to ingestion; however, exposure data for dermal 

pathways are sparse and continue to be the subject of toxicological study. The receptors 

evaluated are consistent with those listed in USEPA guidance for risk screening (USEPA, 2001). 

Receptors at the facility include site workers (e.g., facility staff and visiting soldiers), construction 

workers, trespassers, residents outside the facility boundary, and recreational users outside of 

the facility boundary. 

7.1 Soil Exposure Pathway

The SI results in soil were used to determine whether a potentially complete pathway exists 

between the source and potential receptors at AOI 1 through AOI 6 based on the aforementioned 

criteria. 

7.1.1 AOI 1 

AOI 1 is the Former Building 209, AFFF may have been released through washing and flushing 

firetrucks as well as extinguishing the intentional burn of Building 209. 

PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in surface soil at AOI 1. Site workers, 

construction workers, and trespassers could contact constituents in surface soil via incidental 
Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 7-2

ingestion and inhalation of dust. Therefore, the surface soil exposure pathway for site workers, 

construction workers, and trespassers are potentially complete. PFOA was detected in subsurface 

soil at AOI 1. Construction workers could contact constituents in subsurface soil via incidental 

ingestion; therefore, the subsurface soil exposure pathway for construction workers is potentially 

complete. The CSM for AOI 1 is presented on Figure 7-1. 

7.1.2 AOI 2 

AOI 2 is the Former Building LR200, where AFFF may have been released during a fire training 

exercise that involved the intentional burn of Building LR200. 

PFOS, PFHxS, PFNA, and PFBS were detected in surface soil at AOI 2. Site workers, 

construction workers, and trespassers could contact constituents in surface soil via incidental 

ingestion and inhalation of dust. Therefore, the surface soil exposure pathway for site workers, 

construction workers, and trespassers are potentially complete. PFOA, PFOS, PFHxS, PFNA, 

and PFBS were not detected in subsurface soil at AOI 2; therefore, all exposure pathways are 

considered incomplete. The CSM for AOI 2 is presented on Figure 7-2. 

7.1.3 AOI 3 

AOI 3 is Building 2, which was previously used as a fire station from approximately 2000 to 2012. 

Firetrucks were flushed, rinsed, and washed in the parking lot outside of Building 2. AFFF was 

stored inside the building and used in the firetruck parked outside. 

PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in surface soil at AOI 3. Of these, PFOS 

exceeded the residential SL. Site workers, construction workers, and trespassers could contact 

constituents in surface soil via incidental ingestion and inhalation of dust. Therefore, the surface 

soil exposure pathway for site workers, construction workers, and trespassers are potentially 

complete. PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in shallow subsurface soil at 

AOI 3. Construction workers could contact constituents in subsurface soil via incidental ingestion; 

therefore, the subsurface soil exposure pathway for construction workers is potentially complete. 

The CSM for AOI 3 is presented on Figure 7-3. 

7.1.4 AOI 4 

AOI 4 is a secondary potential release area that consists of the WWTP Holding Ponds and Effluent 

Reuse Area. It is believed that AFFF released in the 200 Area during fire station maintenance 

activities ultimately made its way to the WWTP, and impacted effluent may have been discharged 

to the WWTP Holding Ponds. 

PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in surface soil at AOI 4. Site workers, 

construction workers, and trespassers could contact constituents in surface soil via incidental 

ingestion and inhalation of dust. Therefore, the surface soil exposure pathway for site workers,

construction workers, and trespassers are potentially complete. The CSM for AOI 4 is presented 

on Figure 7-4. 

7.1.5 AOI 5 

Ground-disturbing activities to surface soil and subsurface soil at AOI 5 will not occur given current 

land use restrictions at the AOI (USACE, 2015). Therefore, there are no complete exposure 

pathways in surface soil and subsurface soil. 
Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 7-3

7.1.6 AOI 6 

AOI 6 is comprised of the North and South Holding Ponds, which receive stormwater from the 

Cantonment Area, specifically Building 2, where AFFF discharges have occurred. 

PFOA, PFOS, PFHxS, PFNA, and PFBS was detected in surface soil at AOI 6. PFOS additionally 

exceeded the residential SL. Site workers, construction workers, and trespassers could contact 

constituents in surface soil via incidental ingestion and inhalation of dust. Therefore, the surface 

soil exposure pathway for site workers, construction workers, and trespassers are potentially 

complete. PFOA, PFOS, PFHxS, and PFNA were detected in subsurface soil at AOI 6. 

Construction workers could contact constituents in subsurface soil via incidental ingestion; 

therefore, the subsurface soil exposure pathway for construction workers is potentially complete. 

The CSM for AOI 6 is presented on Figure 7-6. 

7.2 Groundwater Exposure Pathway

The SI results in groundwater were used to determine whether a potentially complete pathway 

exists between the source and potential receptors based on the aforementioned criteria.

7.2.1 AOI 1, AOI 3, and AOI 6 

PFOS was detected above its respective SL in groundwater samples collected from natural 

springs which are fed by the perched aquifer underlying AOI 1, AOI 3, and AOI 6. PFOA, PFHxS, 

and PFBS were detected below their SLs in groundwater. The springs are used for potable water 

at Camp Navajo. There are also domestic drinking water/public supply wells screened in the same 

perched aquifer. Therefore, the ingestion exposure pathway for site workers and off-facility 

residents is potentially complete. The CSMs for AOI 1, AOI 3, and AOI 6 are presented on Figure 

7-1, Figure 7-3, and Figure 7-6, respectively. 

7.2.2 AOI 2 and 4

Groundwater samples were not collected from AOI 2 and 4 because the perched aquifer does not 

exist at AOI 2 or AOI 4. As described in Section 2.2.2, the Wild Bill Hill Basalt aquifer pinches out 

at the springs north of AOI 2 and AOI 4. The geologic layers immediately underlying AOI 2 and 4 

are the Kaibab Formation, the Coconino Sandstone, and the Schnebly Hill/Supai Formations and 

are the primary units associated with the regional aquifer. The exact depth to water from these 

units in the area of AOI 2 and 4 is unknown; however, measurements taken from the regional 

aquifer in the area of Camp Navajo have ranged from several hundred feet to 1,700 feet bgs 

(USACE, 2015; Weston, 2018a).

With the current understanding of the CSM, the ingestion exposure pathway is incomplete for all 

receptors even without AOI-specific groundwater results. Analytical results from AOI 2 and AOI 4 

did shown detections within the surface soil (0 to 2 feet bgs), but not within the shallow subsurface 

or deep soil samples collected indicating potential releases did not migrate into the subsurface. 

Additionally, given the depth to water underlying AOI 2 and AOI 4, it would be difficult for potential 

releases to migrate to the depths necessary to reach the regional aquifer. This is supported by 

the decontamination water sample (collected from CN-2 screened within the regional aquifer) 

result which was non-detect for all PFAS compounds. 

7.2.3 AOI 5 

AOI 5 is a secondary potential release area consisting of NAAD-40, the former sanitary landfill. 

The landfill accepted sludge from the WWTP; the sludge may have been impacted by AFFF 

releases in the 200 Area and cantonment. 
Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 7-4

PFOS and PFBS were detected below their respective SLs in groundwater samples collected at 

AOI 5. There is potential for multiple residential wells off the facility that are screening in shallow 

and regional aquifers to be hydraulically connected to the aquifer at NAAD-40. Therefore, the 

ingestion exposure pathway for off-facility residents is potentially complete. The CSM for AOI 5 is 

presented on Figure 7-5. 

7.3 Surface Water and Sediment Exposure Pathway

The SI results in surface water and sediment were used to determine whether a potentially 

complete pathway exists between the source and potential receptors at each AOI based on the 

aforementioned criteria. Additionally, the SI results in soil and groundwater, in combination with 

knowledge of the fate and transport properties of PFAS, were used to determine whether a 

potentially complete pathway exists between the source and potential receptors.

7.3.1 AOI 1 

It is likely that some surface water runoff at AOI 1 enters the stormwater system and discharges 

to the WWTP holding pond. PFAS are water soluble and can migrate readily from soil to surface 

water via leaching and run-off. Because PFOA, PFOS, PFHxS, PFNA, and PFBS were detected

in soil at AOI 1 and proxy groundwater via the natural springs, it is possible that those compounds 

may have migrated from soil and groundwater to the stormwater system via groundwater 

discharge or the surface water runoff. Additionally, PFOS, PFHxS, and PFBS were detected in 

the sediment sample collected from Atherton Lake. PFOA, PFOS, PFHxS, and PFBS were 

detected in the surface water sample. Atherton Lake is known to capture overflow water from the 

springs which are considered a proxy for groundwater at AOI 1. Therefore, the surface water and 

sediment ingestion exposure pathway for site workers, construction workers, or trespassers is

considered potentially complete. The CSM for AOI 1 is presented on Figure 7-1. 

7.3.2 AOI 2 

Because PFOS, PFHxS, PFNA, and PFBS were detected in soil at AOI 2, it is possible that those 

compounds may have migrated from soil to ephemeral drainage ditch adjacent to AOI 2. 

Therefore, the surface water and sediment ingestion exposure pathway for site workers, 

construction workers, or trespassers is considered potentially complete. The CSM for AOI 2 is 

presented on Figure 7-2. 

7.3.3 AOI 3 

PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in soil at AOI 3 and proxy groundwater 

at the natural springs. Based on the stormwater pathway from the Cantonment Area to the 

Cantonment Area Holding Ponds, which occasionally overflow to Volunteer Wash, it is possible 

that those compounds may have migrated from soil and groundwater to the Cantonment Area 

Holding ponds or Volunteer Wash via groundwater discharge or the surface water runoff. The 

Cantonment Area Holding Ponds may overflow into Volunteer Wash and eventually off-site during 

periods of abnormally high surface water discharge. Additionally, PFOS, PFHxS, and PFBS were 

detected in the sediment sample collected from Atherton Lake. PFOA, PFOS, PFHxS, and PFBS 

were detected in the surface water sample. Atherton Lake is known to capture overflow water 

from the springs which are considered a proxy for groundwater at AOI 3. Therefore, there is a 

potentially complete exposure pathway for surface water and sediment to all receptors. The CSM 

for AOI 3 is presented on Figure 7-3. 
Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 7-5

7.3.4 AOI 4 

PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in soil at AOI 4. Based on the potential 

for PFAS compounds to be present in the holding pond water, and for the holding pond water to 

be discharged to the effluent reuse area, there is a potentially complete exposure pathway for 

surface water and sediment to site workers, construction workers, and trespassers. The CSM for 

AOI 4 is shown on Figure 7-4. 

7.3.5 AOI 5 

PFOS and PFBS were detected in groundwater at AOI 5. The landfill soil cap keeps surface water 

from coming into contact with potential PFAS-containing materials; therefore, there is no complete 

exposure pathway from surface water and sediment to any receptor. The CSM for AOI 5 is shown 

on Figure 7-5. 

7.3.6 AOI 6 

PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in soil at AOI 6 and proxy groundwater 

at the natural springs. Based on the stormwater pathway to the Cantonment Area Holding Ponds, 

which occasionally overflow to Volunteer Wash, it is possible that those compounds may have 

migrated from soil and groundwater to the Cantonment Area Holding ponds or Volunteer Wash 

via groundwater discharge or the surface water runoff. The Cantonment Area Holding Ponds may 

overflow into Volunteer Wash and eventually off-site during periods of abnormally high surface 

water discharge. Additionally, PFOS, PFHxS, and PFBS were detected in the sediment sample 

collected from Atherton Lake. PFOA, PFOS, PFHxS, and PFBS were detected in the surface 

water sample. Atherton Lake is known to capture overflow water from the springs, which are 

considered a proxy for groundwater at AOI 6. Therefore, there is a potentially complete exposure 

pathway for surface water and sediment to all receptors. The CSM for AOI 6 is shown on Figure 

7-6. 
Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 7-6

THIS PAGE INTENTIONALLY BLANK
Media

SOURCE PATHWAY RECEPTOR

AOI 1

Controlled burn of 

Building 209 was 

extinguished with 

AFFF. Other 

potential releases 

during fire station 

operations.

Surface soil

Human 

activities

Precipitation/ 

run-off

Leaching/ 

infiltration

Airborne soil 

particulate

Surface soil 

at AOI

Surface 

water/ 

sediment

Subsurface 

soil

Shallow 

groundwater

Source Release 

Mechanism Media Transport and Migration Media Exposure Routes

Inhalation of 

dust

Ingestion

Ingestion

Ingestion

Ingestion

Human Receptors: 

Current/ Future

Flow-Chart Continues

Partial/ Possible Flow

Flow-Chart Stops

Incomplete Pathway

Potentially Complete Pathway

Potentially Complete Pathway 

with Exceedance of SL

/ / / /

Site Worker Construction Worker Resident1,2 Trespasser

Site Worker Construction Worker Resident1,2

/ / / /

/ / / /

/ / / /

/ / / /

LEGEND

Figure 7-1

Conceptual Site Model, AOI 1

Camp Navajo

Trespasser

1. The residential users refer to off-site receptors.

2. Inhalation of dust for off-site receptors is likely

insignificant.

Notes:

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

7-7
Media

SOURCE PATHWAY RECEPTOR

AOI 2

Controlled burn of

Building LR200 

was extinguished 

with AFFF. 

Surface soil

Human 

activities

Precipitation/ 

run-off

Leaching/ 

infiltration

Airborne soil 

particulate

Surface soil 

at AOI

Surface 

water/ 

sediment

Subsurface 

soil

Shallow 

groundwater

Source Release 

Mechanism Media Transport and Migration Media Exposure Routes

Inhalation of 

dust

Ingestion

Ingestion

Ingestion

Ingestion

Human Receptors: 

Current/ Future

Flow-Chart Continues

Partial/ Possible Flow

Flow-Chart Stops

Incomplete Pathway

Potentially Complete Pathway

Potentially Complete Pathway 

with Exceedance of SL

/ / / /

Site Worker Construction Worker Resident1,2 Trespasser

Site Worker Construction Worker Resident1,2

/ / / /

/ / / /

/ / / /

/ / / /

LEGEND

Figure 7-2

Conceptual Site Model, AOI 2

Camp Navajo

Trespasser

1. The residential users refer to off-site receptors.

2. Inhalation of dust for off-site receptors is likely

insignificant.

Notes:

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

7-8
Media

SOURCE PATHWAY RECEPTOR

AOI 3 Firetruck washing 

and line flushing. Surface soil

Human 

activities

Precipitation/ 

run-off

Leaching/ 

infiltration

Airborne soil 

particulate

Surface soil 

at AOI

Surface 

water/ 

sediment

Subsurface 

soil

Shallow 

groundwater

Source Release 

Mechanism Media Transport and Migration Media Exposure Routes

Inhalation of 

dust

Ingestion

Ingestion

Ingestion

Ingestion

Human Receptors: 

Current/ Future

Flow-Chart Continues

Partial/ Possible Flow

Flow-Chart Stops

Incomplete Pathway

Potentially Complete Pathway

Potentially Complete Pathway 

with Exceedance of SL

/ / / /

Site Worker Construction Worker Resident1,2 Trespasser

Site Worker Construction Worker Resident1,2

/ / / /

/ / / /

/ / / /

/ / / /

LEGEND

Figure 7-3

Conceptual Site Model, AOI 3

Camp Navajo

Trespasser

1. The residential users refer to off-site receptors.

2. Inhalation of dust for off-site receptors is likely

insignificant.

Notes:

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

7-9
Media

SOURCE PATHWAY RECEPTOR

AOI 4

Contaminated

water from the

200 area flows in 

through storm 

drains.

Surface 

water and 

sediment

Human 

activities

Precipitation/ 

run-off

Leaching/ 

infiltration

Airborne soil 

particulate

Surface soil 

at AOI

Surface 

water/ 

sediment

Subsurface 

soil

Shallow 

groundwater

Source Release 

Mechanism Media Transport and Migration Media Exposure Routes

Inhalation of 

dust

Ingestion

Ingestion

Ingestion

Ingestion

Human Receptors: 

Current/ Future

Flow-Chart Continues

Partial/ Possible Flow

Flow-Chart Stops

Incomplete Pathway

Potentially Complete Pathway

Potentially Complete Pathway 

with Exceedance of SL

/ / / /

Site Worker Construction Worker Resident1,2 Trespasser

Site Worker Construction Worker Resident1,2

/ / / /

/ / / /

/ / / /

/ / / /

LEGEND

Figure 7-4

Conceptual Site Model, AOI 4

Camp Navajo

Trespasser

1. The residential users refer to off-site receptors.

2. Inhalation of dust for off-site receptors is likely

insignificant.

Notes:

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

7-10
Media

SOURCE PATHWAY RECEPTOR

AOI 5

Leaching from 

contaminated 

sludge.

Landfill 

contents

Human 

activities

Precipitation/ 

run-off

Leaching/ 

infiltration

Airborne soil 

particulate

Surface soil 

at AOI

Surface 

water/ 

sediment

Subsurface 

soil

Shallow 

groundwater

Source Release 

Mechanism Media Transport and Migration Media Exposure Routes

Inhalation of 

dust

Ingestion

Ingestion

Ingestion

Ingestion

Human Receptors: 

Current/ Future

Flow-Chart Continues

Partial/ Possible Flow

Flow-Chart Stops

Incomplete Pathway

Potentially Complete Pathway

Potentially Complete Pathway 

with Exceedance of SL

/ / / /

Site Worker Construction Worker Resident1,2 Trespasser

Site Worker Construction Worker Resident1,2

/ / / /

/ / / /

/ / / /

/ / / /

LEGEND

Figure 7-5

Conceptual Site Model, AOI 5

Camp Navajo

Trespasser

1. The residential users refer to off-site receptors.

2. Inhalation of dust for off-site receptors is likely

insignificant.

Notes:

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

7-11
Media

SOURCE PATHWAY RECEPTOR

AOI 6

Contaminated

surface water and

sediment enters 

from the storm 

water system.

Surface 

water and 

sediment

Human 

activities

Precipitation/ 

run-off

Leaching/ 

infiltration

Airborne soil 

particulate

Surface soil 

at AOI

Surface 

water/ 

sediment

Subsurface 

soil

Shallow 

groundwater

Source Release 

Mechanism Media Transport and Migration Media Exposure Routes

Inhalation of 

dust

Ingestion

Ingestion

Ingestion

Ingestion

Human Receptors: 

Current/ Future

Flow-Chart Continues

Partial/ Possible Flow

Flow-Chart Stops

Incomplete Pathway

Potentially Complete Pathway

Potentially Complete Pathway 

with Exceedance of SL

/ / / /

Site Worker Construction Worker Resident1,2 Trespasser

Site Worker Construction Worker Resident1,2

/ / / /

/ / / /

/ / / /

/ / / /

LEGEND

Figure 7-6

Conceptual Site Model, AOI 6

Camp Navajo

Trespasser

1. The residential users refer to off-site receptors.

2. Inhalation of dust for off-site receptors is likely

insignificant.

Notes:

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

7-12
Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 8-1

8. Summary and Outcome

This section summarizes SI activities and findings. The most significant findings are summarized 

in this section and are reproduced directly or abstracted from information contained in this report. 

The outcome provides general and comparative interpretations of the findings relative to the SLs. 

8.1 SI Activities 

The SI field activities were conducted from 24 May to 3 June 2021 and consisted of utility clearance, 

soil boring installation and sampling via HSA, grab groundwater sample collection, and sediment, 

and surface water sample collection. Field activities were conducted in accordance with the SI 

QAPP Addendum (AECOM, 2021a), except as previously noted in Section 5.9. 

To fulfill the project DQOs set forth in the approved SI QAPP Addendum (AECOM, 2021a), samples 

were collected and analyzed for a subset of 18 compounds by LC/MS/MS compliant with QSM 5.3 

Table B-15 as follows. 

• Thirty-six (36) soil samples from 23 boring locations; 

• Four grab groundwater samples from four permanent monitoring wells; 

• One sediment and one surface water sample from one location; 

• Five spring samples from five natural spring locations; and 

• Twenty-seven (27) QA/QC samples.

An SI is conducted when the PA determines an AOI exists based on probable use, storage, and/or 

disposal of PFAS-containing materials. The SI includes multi-media sampling at AOIs to 

determine whether or not a release has occurred. The SI may conclude further investigation is 

warranted, a removal action is required to address immediate threats, or no further action is 

required. Additionally, the CSMs were refined to assess whether a potentially complete pathway 

exists between the source and potential receptors for potential exposure at the AOIs, which are 

described in Section 7. 

8.2 Outcome 

Based on the results of this SI, further evaluation under CERCLA is warranted in an RI for AOI 1, 

AOI 3, AOI 5, and AOI 6; no further evaluation is warranted for AOI 2 and AOI 4 at this time (see 

Table 8-1). Based on the CSMs developed and revised in light of the SI findings, there is potential 

for exposure to drinking water receptors from AOI 1, AOI 3, AOI 5, and AOI 6 from sources on the

facility resulting from historical DoD activities. Sample analytical concentrations collected during 

the SI were compared to the project SLs in soil and groundwater, as described in Table 6-1. A 

summary of the results of the SI data relative to the SLs is as follows: 

• At AOI 1, Former Building 209: 

• The detected concentrations of PFOA, PFOS, PFHxS, PFNA and PFBS in soil at 

AOI 1 were below their SLs. 

• PFOS in groundwater exceeded the SL of 4 ng/L with a maximum concentration of 

25.9 ng/L at natural spring location SPG-04, which is fed by the perched aquifer 

underlying AOI 1. Detected concentrations of PFOA, PFHxS, and PFBS in 

groundwater were below their SLs. PFNA was not detected in groundwater. Based 

on the results of the SI, further evaluation of AOI 1 is warranted in an RI.
Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 8-2

• At AOI 2, Former Building LR200: 

• The detected concentrations of PFOS, PFHxS, PFNA, and PFBS in surface soil at 

AOI 2 were below their SLs. PFOA was not detected in surface soil. PFOA, PFOS, 

PFHxS, PFNA, and PFBS were not detected in deep subsurface soil. Based on the 

results and the depth to groundwater, no further action at AOI 2 is warranted. 

• At AOI 3, Building 2: 

• PFOS in surface soil exceeded the SL of 13 μg/kg, with a maximum concentration of 

41.6 μg/kg at location AOI03-01. The detected concentrations of PFOA, PFHxS, 

PFNA, and PFBS in surface soil at AOI 3 were below their SLs. Detected 

concentrations of PFOA, PFOS, PFHxS, PFNA, and PFBS in shallow subsurface soil 

at AOI 3 were below their SLs. PFOA, PFOS, PFHxS, PFNA, and PFBS were not 

detected in deep subsurface soil. Based on the results of the SI, further evaluation of 

AOI 3 is warranted in an RI.

• Like AOI 1, PFOS in groundwater exceeded the SL of 4 ng/L at a spring location that

is fed by the perched aquifer underlying AOI 3. PFOA, PFHxS, and PFBS were 

detected in groundwater below their respective SLs. 

• At AOI 4, WWTP Holding Ponds and Effluent Reuse Site: 

• The detected concentrations of PFOA, PFOS, PFHxS, PFNA, and PFBS in surface 

soil at AOI 4 were below their SLs. Based on the results, limited evidence of 

subsurface migration, and the depth to groundwater, no further action at AOI 4 is 

warranted.

• At AOI 5, NAAD-40: 

• Detected concentrations of PFOS and PFBS in groundwater were below their SLs. 

PFOA, PFHxS, and PFNA were not detected in groundwater. However, there are 

concerns regarding the quality of the samples and representativeness of the results 

with respect to groundwater underlying the AOI. As a result, further evaluation of AOI 

5 is warranted as a conservative measure.. 

• At AOI 6, North and South Holding Ponds: 

• PFOS in surface soil exceeded the SL of 13 μg/kg, with a maximum concentration of 

51.1 μg/kg at location AOI06-01. The detected concentrations of PFOA, PFHxS, 

PFNA, and PFBS in surface soil at AOI 6 were below their SLs. Detected 

concentrations of PFOA, PFOS, PFHxS, and PFNA in shallow subsurface soil were 

below their SLs. PFBS was not detected in shallow subsurface soil. Based on the 

results of the SI, further evaluation of AOI 6 is warranted in an RI.

• Like AOI 1, PFOS in groundwater exceeded the SL of 4 ng/L at a spring location that

is fed by the perched aquifer potentially underlying AOI 6. PFOA, PFHxS, and PFBS 

were detected in groundwater below their SLs. 

• Atherton Lake:

• PFOS, PFHxS, and PFBS were detected in sediment. PFOA and PFNA were not 

detected in sediment. PFOA, PFOS, PFHxS, and PFBS were detected in surface 

water. PFNA was not detected in surface water. There are no established SLs for 

sediment and surface water; therefore, these results are presented for informational 

purposes only. 
Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 8-3

Of the six PFAS compounds presented in the 6 July 2022 OSD memorandum, HFPO-DA 

(commonly referred to as GenX) was not included as an analyte at the time of this SI. Based on 

the CSM developed during the PA and revised based on SI findings, the presence of HFPO-DA 

is not anticipated at the facility because HFPO-DA is generally not a component of MIL-SPEC 

AFFF and based on its history including distribution limitations that restricted use of GenX, it is 

generally not a component of other products the military used. In addition, it is unlikely that GenX 

would be an individual chemical of concern in the absence of other PFAS. 

Table 8-1 summarizes the SI results for soil and groundwater used to determine if an AOI should 

be considered for further investigation under CERCLA and undergo an RI. 

Table 8-1: Summary of Site Inspection Findings and Recommendations

AOI Potential 

Release Area

Soil –

Source Area

Groundwater –

Source Area Future Action

1 Former Building 

209 Proceed to RI 

2 Former Building 

LR200 N/A No further action

3 Building 2 Proceed to RI

4 

WWTP Holding 

Ponds and Effluent 

Reuse Site

N/A No further action

5 NAAD-40 N/A Proceed to RI

6 North and South 

Holding Ponds Proceed to RI

Legend:

= detected; exceedance of the screening levels

= detected; no exceedance of the screening levels

= not detected
Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 8-4

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Site Inspection Report

Camp Navajo, Bellemont, Arizona

AECOM 9-1

9. References 

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WellReg#. 

AECOM. 2018a. Final Site Inspection Programmatic Uniform Federal Policy-Quality Assurance 

Project Plan, Perfluorooctane Sulfonic Acid (PFOS) and Perfluorooctanoic Acid (PFOA) 

Impacted Sites ARNG Installations, Nationwide Contract No. W912DR-12-D-0014/

W912DR17F0192. 9 March.

AECOM. 2018b. Final Programmatic Accident Prevention Plan, Perfluorooctane Sulfonic Acid 

(PFOS) and Perfluorooctanoic Acid (PFOA) Impacted Sites ARNG Installations, Nationwide 

Contract No. W912DR-12-D-0014/W912DR17F0192. July.

AECOM. 2020. Final Preliminary Assessment Report, Camp Navajo, Bellemont, Arizona, 

Perfluorooctane Sulfonic Acid (PFOS) and Perfluorooctanoic Acid (PFOA) Impacted Sites 

ARNG Installations, Nationwide Contract No. W912DR-12-D-0014/W912DR17F0192. 

September.

AECOM. 2021a. Final Site Inspection Uniform Federal Policy-Quality Assurance Project Plan 

Addendum, Camp Navajo, Bellemont, Arizona, Perfluorooctane Sulfonic Acid (PFOS) and 

Perfluorooctanoic Acid (PFOA) Impacted Sites ARNG Installations, Nationwide. April.

AECOM. 2021b. Final Site Safety and Health Plan, Camp Navajo, Bellemont, Arizona, 

Perfluorooctane Sulfonic Acid (PFOS) and Perfluorooctanoic Acid (PFOA) Impacted Sites 

ARNG Installations, Nationwide. May.

Assistant Secretary of Defense. 2022. Investigation Per- and Polyfluoroalkyl Substances within 

the Department of Defense Cleanup Program. United States Department of Defense. 

6 July. 

AZARNG. 2020. Camp Navajo Integrated Natural Resources Management Plan (Revision). 

ADEQ. 2019. Verde Watershed. Retrieved February 13, 2019 from https://legacy.azdeq.gov/

environ/water/assessment/download/vrw.pdf. 

DA. 2018. Army Guidance for Addressing Releases of Per- and Polyfluoroalkyl Substances. 

4 September.

DoD. 2019a. Department of Defense (DoD), Department of Energy (DOE) Consolidated Quality 

Systems Manual (QSM) for Environmental Laboratories, Version 5.3. 

DoD. 2019b. General Data Validation Guidelines. Environmental Data Quality Workgroup. 

4 November.

Guelfo, J.L. and Higgins, C.P. 2013. Subsurface Transport Potential of Perfluoroalkyl Acids at 

Aqueous Film-Forming Foam (AFFF)-Impacted Sites. Environmental Science and Technology 

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Higgins, C.P., and Luthy, R.G. 2006. Sorption of perfluorinated surfactants on 

sediments. Environmental Science and Technology 40 (23): 7251-7256.

ITRC. 2018. Environmental Fate and Transport for Per- and Polyfluoroalkyl Substances. March. 

Jacobs Engineering. 2017. Camp Navajo Vision Plan - AZARNG 2017. 
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AECOM 9-2

Thorstenson, Don J. and Beard, Sue L. 1998. Geology and Fracture Analysis of Camp Navajo, 

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Open File Report 98-242

USACE. 2015. Five-Year Review Report. October. 

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USEPA. 1980. Comprehensive Environmental Response, Compensation, and Liability Act 

(CERCLA). 

USEPA. 1994. National Oil and Hazardous Substances Pollution Contingency Plan (Final Rule). 

40 CFR Part 300; 59 Federal Register 47384. September.

USEPA. 2001. Risk Assessment Guidance for Superfund, Volume I: Human Health Evaluation 

Manual (Part D, Standardized Planning, Reporting, and Review of Superfund Risk 

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USEPA. 2017. National Functional Guidelines for Organic Superfund Data Review. OLEM 

9355.0-136, EPA-540-R-2017-002. Office of Superfund Remediation and Technology 

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USFWS. 2022. Information for Planning and Consultation, Endangered Species, Location: 

Coconino County, Arizona. Environmental Conservation Online System. Accessed 6 

September 2022 at https://ecos.fws.gov/ecp/report/species-listings-by-current-rangecounty?fips=04005. September.

Weston. 2018a. Annual 2017 Post Closure Care Report For NAAD-02 and Regional Aquifer 

Wells. January.

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for NAAD Sites 11B, 40, 43, 01, and 20. January.

Wilkinson, Randall W. 2000. Water Resources of Bellemont Park, Coconino County, Arizona. In 

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Xiao, F., Simcik, M. F., Halbach, T. R., and Gulliver, J. S. 2015, Perfluorooctane sulfonate (PFOS) 

and perfluorooctanoate (PFOA) in soils and groundwater of a U.S. metropolitan area: 

Migration and implications for human exposure. Water Research 72: 64-74