FINAL 

Preliminary Assessment Report

Camp Navajo

Bellemont, Arizona

Perfluorooctanesulfonic Acid (PFOS) and Perfluorooctanoic 

Acid (PFOA) Impacted Sites

ARNG Installations, Nationwide

September 2020

Prepared for:

Army National Guard Bureau

111 S. George Mason Drive

Arlington, VA 22204
PFAS Preliminary Assessment Report

Camp Navajo, Bellemont, AZ

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Table of Contents

Executive Summary....................................................................................................1

1. Introduction ........................................................................................................................ 5

1.1 Authority and Purpose .............................................................................................. 5

1.2 Preliminary Assessment Methods ............................................................................. 5

1.3 Report Organization .................................................................................................. 6

1.4 Installation Location, Description and Background .................................................... 6

1.5 Installation Environmental Setting ............................................................................. 7

1.5.1 Geology ......................................................................................................... 7

1.5.2 Hydrogeology ................................................................................................. 8

1.5.3 Hydrology ....................................................................................................... 8

1.5.4 Climate ........................................................................................................... 9

1.5.5 Current and Future Land Use ....................................................................... 10

2. Fire Training Areas ........................................................................................................... 14

2.1 Former Building 209................................................................................................ 14

2.2 Former Building LR200 ........................................................................................... 14

3. Non-Fire Training Areas ................................................................................................... 17

3.1 Building 2 ................................................................................................................ 17

3.2 Buildings 333 & 334 – WWTP ................................................................................. 17

3.3 Holding Ponds ....................................................................................................... 18

3.4 NAAD-40 ............................................................................................................... 18

3.5 North and South Holding Ponds .............................................................................. 18

3.6 Building K2009 ........................................................................................................ 19

4. Emergency Response and Other PFAS Uses .................................................................. 21

5. Adjacent Sources ............................................................................................................. 22

6. Preliminary Conceptual Site Model .................................................................................. 23

6.1 AOI 1 Former Building 209...................................................................................... 23

6.2 AOI 2 Former Building LR200 ................................................................................. 24

6.3 AOI 3 Building 2 ...................................................................................................... 24

6.4 AOI 4 Holding Ponds ............................................................................................. 25

6.5 AOI 5 NAAD-40 ...................................................................................................... 25

6.6 AOI 6 North and South Holding Ponds .................................................................... 26

7. Conclusions ..................................................................................................................... 34

7.1 Findings .................................................................................................................. 34

7.2 Uncertainties ........................................................................................................... 35

7.3 Potential Future Actions .......................................................................................... 36

8. References ...................................................................................................................... 38
PFAS Preliminary Assessment Report

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Figures

Figure ES-1 Summary of Findings

Figure ES-2 Preliminary Conceptual Site Model

Figure 1-1 Installation Location

Figure 1-2 Groundwater Features

Figure 1-3 Surface Water Features

Figure 2-1 Fire Training Areas

Figure 3-1 Non-Fire Training Areas

Figure 6-1 Area of Interest

Figure 6-2 Preliminary Conceptual Site Model, AOI 1

Figure 6-3 Preliminary Conceptual Site Model, AOI 2

Figure 6-4 Preliminary Conceptual Site Model, AOI 3

Figure 6-5 Preliminary Conceptual Site Model, AOI 4

Figure 6-6 Preliminary Conceptual Site Model, AOI 5

Figure 6-7 Preliminary Conceptual Site Model, AOI 6

Figure 7-1 Summary of Findings

Appendices

Appendix A Data Resources

Appendix B Preliminary Assessment Documentation

B.1 Interview Records

B.2 Visual Site Inspection Checklists

B.3 Conceptual Site Model Information

Appendix C Photographic Log

Tables

Table ES- 1 Camp Navajo PA AOIs

Table 7-1 Camp Navajo PA AOIs

Table 7-2 Uncertainties within the PA

Table 7-3 PA Findings Summary
PFAS Preliminary Assessment Report

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Acronyms and Abbreviations

AECOM AECOM Technical Services, Inc.

AFFF aqueous film forming foam

AOI Area of Interest

ARNG Army National Guard

AZARNG Arizona Army National Guard

bgs below ground surface

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act

CFR Code of Federal Regulations

CSM Conceptual Site Model

DESCOM Army Depot System Command’s

EDRTM Environmental Data Resources, Inc.TM

°F Fahrenheit

FTA Fire Training Areas

gpd gallons per day

gpm gallons per minute

N

NAAD

North

Navajo Army Depot

NADA Navajo Army Depot Activity

NOD Navajo Ordnance Depot

PA Preliminary Assessment

PFAS Per- and Poly-fluoroalkyl Substances

PFOA Perfluorooctanoic Acid

PFOS Perfluorooctanesulfonic Acid

US United States

USACE United States Army Corps of Engineers

USEPA United States Environmental Protection Agency

W West

WWTP Waste Water Treatment Plant
PFAS Preliminary Assessment Report

Camp Navajo, Bellemont, AZ

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Executive Summary

The United States (US) Army Corps of Engineers Sacramento District on behalf of the Army

National Guard (ARNG), Cleanup Branch contracted AECOM Technical Services, Inc. (AECOM)

to perform Preliminary Assessments (PAs) and Site Inspections (SIs) for Perfluorooctanesulfonic

acid (PFOS) and Perfluorooctanoic acid (PFOA) Impacted Sites at ARNG Facilities Nationwide.

The ARNG is assessing potential effects on human health related to processes at facilities that

used per- and poly-fluoroalkyl substances (PFAS) (a suite of related chemicals), primarily in the

form of aqueous film forming foam (AFFF) discharged during firefighting activities or training,

although other PFAS sources are possible.

AECOM completed a PA for PFAS at the Arizona ARNG (AZARNG) Camp Navajo in Bellemont,

Arizona, to identify areas of known or suspected releases known as Areas of Interest (AOI) and

exposure pathways to receptors. The performance of this PA included the following tasks:

· Reviewed available administrative record documents and Environmental Data Resources,

Inc. report packages to obtain information relevant to potential PFAS releases

· Conducted a 2-day PA site visit on 5 and 6 November 2018

· Interviewed current Camp Navajo personnel during the PA site visit including the AZARNG

cleanup support manager, Fire Department Captain, Site Utilities Manager, Programs and

Projects Specialist, and Physical Plant Supervisor II

· Completed visual site inspections at known or suspected PFAS release locations and

documented them in photographs

· Identified areas of interest (AOIs) and developed a conceptual site model (CSM) to

summarize potential source-pathway-receptor linkages of potential PFAS in soil,

groundwater, surface water, and sediment for each AOI

Six AOIs related to potential PFAS releases were identified at Camp Navajo during the PA. The

AOIs are shown on Figure ES-1 and described in Table ES-1 below.

Table ES- 1: Camp Navajo PA AOIs

Area of Interest Name Used by

AOI 1 Former Building 209 ARNG/AZARNG

AOI 2 Former Building LR200 ARNG/AZARNG

AOI 3 Building 2 ARNG/AZARNG

AOI 4 Holding Ponds ARNG/AZARNG

AOI 5 NAAD-40 ARNG/AZARNG

AOI 6 North and South Holding

Ponds ARNG/AZARNG

Based on the documented primary and secondary PFAS releases at these AOIs, there is potential

for exposure to PFAS contamination in media at or near the facility. The preliminary CSM for

Camp Navajo is shown on Figure ES-2, which presents the potential receptors and media

impacted. Based on the US Environmental Protection Agency (USEPA) Unregulated Contaminant

Monitoring Rule 3 data, it was indicated that no PFAS were detected in a public drinking water
PFAS Preliminary Assessment Report

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system above the USEPA Health Advisory level (70 parts per trillion for PFOA and PFOS) within

20 miles of the facility.

ARNG will evaluate the need for an SI at AOIs 1, 2, 3, 4, 5, and 6 at Camp Navajo based on the

potential receptors and the potential migration of PFAS contamination off the installation. ARNG

sites will be prioritized for SIs based on funding.
200 Area

Building 2

Former Building 209

Former Building LR200

North Holding Pond

South Holding Pond

NAAD-40

Holding Ponds

Reuse Site

Buildings 333 & 334

Building K2009

AOI 2

AOI 3

AOI 1

AOI 5

AOI 4

AOI 6

C:\Users\stankevichm\OneDrive - AECOM Directory\ARNG_PFAS_GIS_60552172\MXDs\AZ\Camp_Navajo_Figures\Camp_Navajo_PA_Figures\Fig_ES-1_Camp_Navajo_Summary.mxd

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Feet

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Preliminary Assessment for PFAS at Camp Navajo, AZ

9/17/2020

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Area of Interest

Potential PFAS Release

No Suspected Release

Facility Boundary

Summary of Findings

12420 Milestone Center Drive

Germantown, MD 20876

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Media

SOURCE PATHWAY RECEPTOR

All AOIs:

Former

Building

209, Former

Building

LR200,

Building 2,

WWTP

Holding

Ponds &

Effluent

Reuse Area,

Former

Sanitary

Landfill

(NAAD-40),

and

Cantonment

Area

Holding

Ponds

Fire suppression,

leaking truck, truck

wash runoff,

secondary releases

Human

Activities

Precipitation/

Run-Off

Leaching/

Infiltration

Airborne Soil

particulate

Surface Soil

Surface

Water/

sediment

Subsurface

Soil

Groundwater

Source Release

Mechanism Media Transportand Migration Media ExposureRoutes

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

Complete Pathway

Installation

Worker

Construction

Worker

Off-installation

Resident

Visitor/

Trespasser

Installation

Worker

Construction

Worker

Off-installation

Resident

Visitor/

Trespasser

/ / /

/ /

LEGEND

/ /

/ / /

Figure ES-2

Preliminary Conceptual Site Model

Camp Navajo

/

/

/

/ /

PFAS in

Surface Soil,

Surface

Water, and

Landfill

Contents

Notes: 1) 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 is sparse and continues to be the subject of PFAS

toxicological study.

 2) Deep groundwater (~1,500 to 1,700 feet below ground surface) and shallow

perched groundwater (~10 to 20 feet below ground surface) are both used for

potable purposes at Camp Navajo.

/

/

/

/ /

Potential

OffInstallation

Source Not

under

Control of

ARNG

44
PFAS Preliminary Assessment Report

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1. Introduction

1.1 Authority and Purpose

The United States (US) Army Corps of Engineers (USACE) Sacramento District on behalf of the

Army National Guard (ARNG) G9, Cleanup Branch contracted AECOM Technical Services, Inc.

(AECOM) to perform Preliminary Assessments (PAs) and Site Inspections (SIs) for

Perfluorooctanesulfonic acid (PFOS) and Perfluorooctanoic acid (PFOA) Impacted Sites at ARNG

Facilities Nationwide under Contract Number W912DR-12-D-0014, Task Order

W912DR17F0192, issued 11 August 2017. The ARNG is assessing potentially impacted facilities

that used per- and poly-fluoroalkyl substances (PFAS) (a suite of related chemicals including

PFOS and PFOA). PFAS are most commonly used in AFFF discharged as part of firefighting

activities, fire training, and equipment testing or maintenance. Other sources of PFAS include, for

example, metal plating and uniform weatherproofing. This PA also evaluates potential PFAS

sources with a 1-mile radius of Camp Navajo that are not under the control of ARNG or AZARNG.

PFAS are classified as emerging environmental contaminants that are garnering increasing

regulatory interest due to their potential risks to human health and the environment. The regulatory

framework at both federal and state levels continues to evolve. The US Environmental Protection

Agency (USEPA) issued Drinking Water Health Advisories for two PFAS, PFOA and PFOS, in

May 2016 (70 parts per trillion), but there are currently no promulgated national standards

regulating PFAS. In the absence of federal standards, some states have adopted their own

standards. However, the State of Arizona does not currently have promulgated standards for

PFAS.

This PA presents findings for PFAS presence and historical use at the Arizona Army National

Guard (AZARNG) Camp Navajo in Bellemont, Arizona in accordance with the Comprehensive

Environmental Response, Compensation, and Liability Act (CERCLA), as amended, the National

Oil and Hazardous Substances Pollution Contingency Plan (40 Code of Federal Regulations Part

300), and USACE requirements and guidance.

This PA documents the known fire training areas (FTAs) as well as additional locations where

PFAS may have been released to the environment at Camp Navajo (i.e., non-FTAs). The term

PFAS, as used in this PA, refers to the entire suite of per- and polyfluoroalkyl substances,

including PFOS and PFOA. PFOS and PFOA are the primary components of AFFF, which has

been managed at Camp Navajo. If a known or suspected discharge of AFFF and, therefore, a

known or suspected release of PFAS has occurred, that location is designated an Area of Interest

(AOI). The process for conducting the PA is discussed in the next section.

1.2 Preliminary Assessment Methods

The following tasks were performed as part of this PA:

· Reviewed available administrative record documents and Environmental Data Resources,

Inc.TM (EDRTM) report package (Appendix A) to obtain information relevant to suspected

PFAS releases;

· Conducted a PA site visit on 5 and 6 November 2018. All associated documentation is

provided in Appendix B;

· Interviewed current Camp Navajo personnel including the AZARNG IED Cleanup Support

Manager, Fire Department Captain, Site Utilities Manager, Programs and Projects Specialist,

and Physical Plant Supervisor II;
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· Completed visual site inspection at known or suspected AFFF discharge locations and

documented them in photographs. A photo log is provided in Appendix C; and

· Developed a conceptual site model (CSM) describing the source, pathway, receptor links for

each of the AOIs.

1.3 Report Organization

This report has been prepared in accordance with the USEPA Guidance for Performing

Preliminary Assessments under CERCLA (US EPA, 1991). The report sections and descriptions

of each are:

· Section 1 – Introduction identifies the project purpose and authority and describes the

installation location, environmental setting, and methods used to complete the PA;

· Section 2 – Fire Training Areas: describes the FTAs at the installation identified during the

site visit;

· Section 3 – Non-Fire Training Areas: describes other locations of potential or suspected

PFAS releases at the installation identified during the site visit;

· Section 4 – Emergency Response Areas: describes areas of suspected or potential PFAS

release at the installation, specifically in response to emergency situations;

· Section 5 – Adjacent Sources: describes sources of PFAS release adjacent to the

installation that are not under the control of ARNG or AZARNG;

· Section 6 – Conceptual Site Model describes the pathways of PFAS transport and

receptors at the installation;

· Section 7 – Conclusions summarizes the findings and presents the conclusions of the PA;

· Section 8 – References provides the references used to develop this document.

· Appendix A – Data Resources

· Appendix B – Preliminary Assessment Documentation

· Appendix C – Photographic Log

1.4 Installation Location, Description and Background

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 (approximate population 300)

located along Interstate 40 (I-40) (Figure 1-1). The installation 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 used to support the

installation’s munitions/missile storage mission and support of various training missions

(AZARNG, 2014).

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 installation

was completed in 1943 (AZARNG, 2014).
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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, 2014).

1.5 Installation Environmental Setting

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

at an elevation of approximately 7,050 feet. 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 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 ft – 1,700 ft 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. 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,

2019). 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, and no springs

issue from the carbonate rocks. This suggests that a significant amount of the infiltrate percolates

downward to recharge the regional aquifers.

1.5.1 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, separated by

the physiographic boundary of the Mogollon Rim approximately six 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.
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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 1.5.2.

Structurally, the northeasterly-striking Bellemont Fault bisects Camp Navajo (Figure 1-2), 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).

1.5.2 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

(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).

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

Environmental Management Office, there are monitoring wells and potable water wells on the

installation and to the north of Camp Navajo. According to the Arizona Department of Water

Resources there are approximately 200 wells within one mile of the installation’s boundary

(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 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 (Figure 1-2).

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. The springs are fed by shallow perched groundwater

from the Wild Bill Hill basalt. This shallow groundwater generally recharges and flows from the

north to the south and discharges at the springs. The installation has the ability to pull water from

Reservoir 1. Water is stored primarily at the water tower with 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 sprinkler systems.

Based on the USEPA Unregulated Contaminant Monitoring Rule 3 data, it was indicated that no

PFAS were detected in a public drinking water system above the USEPA Health Advisory level

(70 parts per trillion for PFOA and PFOS) within 20 miles of the facility.

1.5.3 Hydrology

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

miles of land (AZDEQ, 2019). Volunteer Wash is the main surface water drainage channel and
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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 1-3.

Surface water on the installation 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, 2014).

Surface water runoff immediately west of the Bellemont Fault (Figure 1-3) drains toward the

ephemeral Atherton Lake, which overflows into two adjacent sinkholes. Runoff in the 200 area

flows north and discharges into a ditch adjacent to I-10. This ditch eventually flows to the east

and drains to Volunteer Wash. Sheet runoff from other areas of the installation 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.

1.5.3.1 Storm and Sewer Water Infrastructure

This section discusses areas of the Camp Navajo storm and sewer water infrastructure that

represent possible pathways for potential AFFF discharges in certain areas of the installation.

These potential discharges are discussed in detail in Sections 2, 3, and 6.

According to the 6 November 2018 interview with Camp Navajo’s Utilities Manager, storm drains

at Building 2 and the rest of the cantonment area drain to holding ponds to the east. During periods

of high stormwater discharge, these holding ponds drain into an ephemeral creek further to the

east, and eventually off-installation to the south. According to the Utilities Manager, the drains

have not been reconfigured within the past 20 years.

Building 218, an auto maintenance facility, has drains and sumps that connected to the sewage

system. Other buildings in the 200 Area, including Building 209, reportedly had a similar sewage

connection. However, this sewer collection system was reportedly abandoned in 2008 (Appendix

B). Camp Navajo personnel suspect that some runoff in the 200 Area drains to the WWTP and

the associated WWTP holding pond. According to the 6 November 2018 interview with Camp

Navajo’s utilities manager, it is possible that old storm drains in the 200 Area are still tied into the

WWTP, as observed flow rates into the plant are much higher than expected, especially during

rain events. Surface water in the 200 Area runs off-installation to the north, however, surface water

readily infiltrates into the underlying Wild Hill Basalt in this area (Wilkinson, 2000).

The Camp Navajo WWTP is capable of treating 60,000 gallons per day (Jacobs, 2017). Domestic

and pre-treated industrial wastewater generated at Camp Navajo is discharged to the WWTP. The

treated effluent is subsequently discharged to holding ponds for evaporation. Any effluent that is

in excess of the capacity of the holding ponds can be applied to a permitted re-use site (Figure

3-1) which consists of 20-acres to the southeast of Reservoir 1 (Jacobs, 2017). Dried sewage

sludge was disposed of at the Sanitary Landfill (Figure 3-1) at Camp Navajo from 1966 – 1981

(Weston, 2018b).

1.5.4 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
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direction is south-southwest. The mean temperature is 45.6 degrees Fahrenheit (°F), with

extreme temperatures up to at least 94 °F and down to at least -30 °F. Annual precipitation ranges

between 18-22 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 97 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, 2014).

1.5.5 Current and Future Land Use

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

(AZARNG, 2014). 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

of storage and provides capacity to both the Navy and Air Force (Jacobs, 2017). Camp Navajo

can be divided into four areas based on use:

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

and a warehouse area.

2. The Limited Area stores various commodities, predominantly munitions and missile motors.

3. The historic Open Burn/Open Detonation Area, used for demilitarization of munitions, is

now referred to as the Post-Closure Permit Area (PCPA).

4. 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.

Camp Navajo is anticipated to remain used for military training and munitions storage in the future.
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Q:\Projects\ENV\GEARS\GEO\ARNG PFAS\900-CAD-GIS\920-GIS or Graphics\MXD\AZ\Camp_Navajo_Figures\Camp_Navajo_PA_Figures\Fig_1-2_Camp_Navajo_Groundwater.mxd

Groundwater Features

Figure 1-2 12420 Milestone Center Drive ­ Germantown, MD 20876

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USDA, USGS, AeroGRID, IGN, 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.

12
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Figure 1-3 12420 Milestone Center Drive ­ Germantown, MD 20876

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Base Map: Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS,

USDA, USGS, AeroGRID, IGN, and the GIS User Community

13
PFAS Preliminary Assessment Report

Camp Navajo, Bellemont, AZ

14

2. Fire Training Areas

FTAs are considered areas where intentional discharges of AFFF or other firefighting materials is

performed for purposes of training personnel. Two FTAs were identified during the PA (Figure 2-

1). These include a former fire station (former Building 209), and a former lunch room building

(former LR 200). Both of these former structures were intentionally burned during fire training

exercises.

2.1 Former Building 209

The Former Building 209, former fire station, is located in the 200 Area (Figure 2-1). The

geographic coordinates of the approximate center of the former building are 35°13’50.6’’ North

(N), 111°50’03.2’’ West (W). According to interviews conducted during the PA site visit and aerial

photographs, Building 209 was demolished between 2000 – 2003 (Appendix A & Appendix B).

No information was obtained about the operations 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. As discussed in Section 3.1, 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. The Macy

truck was used for installation firefighting activities and was likely used to extinguish the Building

209 fire. Camp Navajo’s Macy truck had a 600-gallon water tank and a 60-gallon foam tank.

According to aerial photographs and the site visit, the 200 Area is mostly bare earth, with the

exception of concrete foundations of former buildings (Appendix A). The area around Former

Building 209 is bare earth, and the roads are unpaved. According to PA site visit documentation,

a storm drain exists to the west of the Former Building 209 area. The storm drain may lead to an

outfall to the east, which potentially enters the ephemeral drainage ditch that feeds to Reservoir

1. A separate drainage ditch to the south of Former Building 209 runs immediately toward the

east, and then ultimately to the north, where it appears runoff would pond and infiltrate.

Due to the abundance of bare earth in the vicinity of Former Building 209, it is likely that AFFF

used during the intentional burn of Building 209 would have infiltrated into the subsurface. The

200 Area has a high rate of surface water infiltration, which recharges the natural springs to the

south. The Camp Navajo Utilities Manager suspects that stormwater in the 200 Area may also

enter the abandoned sewer system, or old storm drains, and eventually reach the WWTP.

2.2 Former Building LR200

Former Building LR200, former lunch room, is located on the southern end of the installation in

the storage area (Figure 2-1). The geographic coordinates at the approximate center of the former

building are 35°12’32.1’’ N, 111°50’34.0’’ W. Building LR200 was used as a lunch room and was

demolished by intentional burn. An unknown quantity of AFFF was likely used to suppress the fire

(Appendix B). The exact date of the fire training exercise that demolished the building is not

known; however, the physical plant supervisor, who was with the fire department at Camp Navajo

from 1994 – 1999, recalls the training exercise. The Former Building LR200 area is currently used

as a storage field for construction materials.

The area where Building LR200 stood is currently a patch of exposed earth. According to

observations made during the PA site visit, a drainage ditch is located along the western side of

the Former Building LR200 footprint. The drainage ditch runs north-south and likely flows towards
PFAS Preliminary Assessment Report

Camp Navajo, Bellemont, AZ

15

the south end of the installation, consistent with regional drainage patterns. There is a sinkhole

on the eastern side of the Former Building LR200 area with an escarpment consistent with the

north-south orientation of the Bellemont Fault. Water that enters this sinkhole is likely in

communication with the regional aquifer. It is likely that AFFF was used during this training activity

and it infiltrated to the subsurface. Water and AFFF infiltrating at the surface have the potential to

eventually leach to the regional aquifer.
Former

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12420 Milestone Center Drive

Germantown, MD 20876

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Intermap, INCREMENT P, NRCan, Esri Japan, METI,

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PFAS Preliminary Assessment Report

Camp Navajo, Bellemont, AZ

17

3. Non-Fire Training Areas

Locations that are considered non-FTAs include but are not limited to, hangars, fire stations,

emergency response, and other locations where AFFF was discharged or had potential to be

discharged to the environment. AFFF may have been discharged to the environment in these

areas via leaks, maintenance and testing, disposal of product, non-training related firefighting

activities, and migration through the environment.

The PA site visit identified six non-FTAs. Each non-FTA is shown on Figure 3-1. Available

photographs of each non-FTA visited during the PA are presented in Appendix C and a

description of each non-FTA is presented below.

3.1 Building 2

Building 2, former fire station, is located in the cantonment area at the northern end of the

installation (Figure 3-1). The geographic coordinates at the approximate center of the building

are 35°13’41.7’’ N, 111°49’19.6’’ W. Building 2 was constructed in 1942 (Tetra Tech, 1997) and

was used as a fire station after Building 209 was destroyed until approximately 2012 when the

new fire station was constructed (Appendix B). The type and frequency of firetruck maintenance

activities performed in this area are unknown. No staining or residue were observed within the

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

station and was used in a Macy Firetruck, which was parked at the station (Appendix B).

Firetrucks and hose lines were flushed, rinsed, and washed outside of Building 2 in the parking

lot. 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 (Appendix A). Those areas of bare earth were located directly

adjacent to paved roads and the parking lot. It is possible that wash water and residual AFFF

reached the swaths of bare earth. During the PA site visit, a paved parking area was observed off

the northeast corner of the building. The parking lot has two storm drains which direct runoff to

the east into two holding ponds. These storm drains are shown on Photograph No. 2 in Appendix

C and the holding ponds are discussed further in Section 3.5.

3.2 Buildings 333 & 334 – WWTP

The Waste Water Treatment Plant (WWTP), which is labeled as Buildings 333 & 334 on the

attached figures, is located to the south of the cantonment and 200 Areas at 35°13’03.3’’ N,

111°49’54.4’’ W. A former WWTP was historically located in the same area. The WWTP can treat

up to 60,000 gpd. Domestic and pre-treated industrial wastewater generated at Camp Navajo is

discharged to the WWTP; however, The Utilities Manager suspects that stormwater in the 200 

Area may reach the WWTP via pathways in the abandoned sewer system, or old storm drains.

There is the potential for stormwater from the 200 Area to reach the WWTP. Given the potential

for AFFF discharge to have occurred in the 200 Area, there is the potential for PFAS contaminated

water to have reached the WWTP. Treatment processes at the WWTP do not remove PFAS; 

therefore, PFAS contaminated water would have been discharged to the holding ponds after the

treatment process. The stormwater discharge lines from the 200 Area to the WWTP are included

in the consideration of this non-FTA. Sludge from both WWTPs has been disposed of in the

Former Sanitary Landfill (NAAD-40).
PFAS Preliminary Assessment Report

Camp Navajo, Bellemont, AZ

18

3.3 Holding Ponds

The Holding Ponds, refers specifically to the WWTP Holding Ponds and Effluent Reuse Area.

Stormwater runoff from the 200 Area is suspected to enter abandoned storm drains and sewer

lines leading to the WWTP. Therefore, PFAS-contaminated WWTP effluent may be discharged to

the WWTP Holding Ponds. The currently used WWTP Holding Pond is located to the south of the

WWTP at 35°12’46.4’’ N, 111°49’59.7’’ W. The formerly used WWTP Holding Ponds are located

immediately to the east at 35°12’42.1’’ N, 111°49’51.5’’ W. 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 at which water is held to infiltrate and evaporate. An effluent reuse area

is connected to the new pond, and water in excess of the pond’s capacity can be diverted to the

reuse area (Figure 3-1). Until 1981, sludge from the WWTPs was removed and disposed of at

the Former Sanitary Landfill (NAAD-40).

3.4 NAAD-40

NAAD-40, also known as the Former Sanitary Landfill, is located on the eastern side of the

installation at 35°12’50.5’’ N, 111°48’30.2’’ and takes up about 6-acres. NAAD-40 received

household and various other wastes from the 1940s until 1966. Dried sewage effluent sludge was

disposed of at NAAD-40 between 1966 and 1981. The landfill has been inactive since 1981 and

an engineered cap was constructed in 2001 (Weston, 2018b). NAAD-40 is an unlined landfill, and

six groundwater and four vapor monitoring wells are monitored as part of the Department of

Defense’s Installation Restoration Program. There are two access points to the landfill: one by

locked gate on the western side and another from the northern side of NAAD-40. Due to the

rugged terrain, no vehicular traffic is permitted beyond the western boundary of the landfill cap

(Weston, 2018b).

According to interviews with Camp Navajo personnel, there is a possible stormwater pathway

from the 200 Area to the WWTP. There has been documented use of AFFF in the 200 Area during

the intentional burn of Former Building 209, former fire station, between 2000 – 2005, which

occurred after the Sanitary Landfill stopped receiving WWTP sludge. However, while Building 2

was in operation as a firehouse prior to 2000, it is likely that operations mimicked the documented

operations at Building 2, former fire station. In this case, truck washing and line flushing activities

may have released PFAS to the stormwater system in the 200 Area, which would have traveled

to the WWTP Pond and ended up in the sludge disposed of at the Former Sanitary Landfill.

3.5 North and South Holding Ponds

The North and South Holding Ponds refers specifically to the Cantonment Area Holding Ponds.

There are two Cantonment Area Holding Ponds which are ephemeral and are located to the east

of the Cantonment Area. They receive storm water runoff from the Cantonment Area, specifically

Building 2, where AFFF discharges have occurred. The center of the northernmost pond is located

at approximately 35°13’34.8’’ N, 111°49’07.3’’ W. The center of the southernmost pond is located

at approximately 35°13’32.4’’ N, 111°49’06.4’’ W.

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, off the installation, toward

Volunteer Wash. Due to the documented presence and discharge of AFFF at Building 2, there is

a possible PFAS pathway from the storm drains at Building 2 to the Cantonment Area Holding
PFAS Preliminary Assessment Report

Camp Navajo, Bellemont, AZ

19

Ponds, and subsequently off the installation. The stormwater discharge lines from the Building 2

drains to the ponds are included in the consideration of this non-FTA.

3.6 Building K2009

Building K2009, current fire station, was constructed as a replacement for the Building 2 fire

station in 2009, and is located in the Cantonment Area. The coordinates at the center of the

building are 35°13’40.2’’ N, 111°49’14.7’’ W. Building K2009 only uses Class A foam (Appendix

B); however, a misshipment of AFFF was sent to the station, and during the PA site visit two 5-

gallon buckets of 6% AFFF were being stored in the station on Engine 911. No discharges of

AFFF at Building K2009 have occurred.
200 Area

Building 2

North Holding Pond

South Holding Pond

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Reuse Site

Buildings 333 & 334

Building K2009

C:\Users\stankevichm\OneDrive - AECOM Directory\ARNG_PFAS_GIS_60552172\MXDs\AZ\Camp_Navajo_Figures\Camp_Navajo_PA_Figures\Fig_3-1_Camp_Navajo_Non-Fire_Training_Areas.mxd

0 750 1,500 3,000

Feet

Legend

Potential PFAS Release

No Suspected Release

Facility Boundary

Non-Fire Training Areas

Figure 3-1 12420 Milestone Center Drive ­ Germantown, MD 20876

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PM RG 9/17/2020

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Base Map: National Agricultural Imagery Program, 2017.

20
PFAS Preliminary Assessment Report

Camp Navajo, Bellemont, AZ

21

4. Emergency Response and Other PFAS Uses

No emergency responses or other PFAS uses were identified during the PA site visit.
PFAS Preliminary Assessment Report

Camp Navajo, Bellemont, AZ

22

5. Adjacent Sources

According to the EDRTM report, there are no properties within a 1-mile radius, hydraulically upgradient of the installation where there is potential for PFAS releases to the environment. The

surrounding land uses are residential and commercial.
PFAS Preliminary Assessment Report

Camp Navajo, Bellemont, AZ

23

6. Preliminary Conceptual Site Model

Based on the PA, six AOIs have been identified at Camp Navajo: AOI 1 Former Building 209, AOI

2 Former Building LR200, AOI 3 Building 2, AOI 4 Holding Ponds, AOI 5 NAAD-40, and AOI 6

North and South Holding Ponds. The AOI locations are shown on Figure 6-1. The following

sections describe the CSM components and the specific CSMs developed for each AOI. The CSM

includes the three components necessary for a potentially complete exposure pathway: (1)

source, (2) pathway, and (3) receptor. If any of these elements are missing, the pathway is

considered incomplete.

In general, the potential PFAS exposure pathways are ingestion and inhalation. Human exposure

via the dermal contact pathway may occur, and current risk evaluation practice suggests it is an

insignificant pathway compared to ingestion; however, exposure data for dermal pathways is

sparse and continues to be the subject of PFAS toxicological study. Potential PFAS receptors at

Camp Navajo include installation workers, construction workers, off-installation residents, and

visitors/trespassers. The CSMs for each AOI indicate which specific receptors could potentially

be exposed to PFAS.

6.1 AOI 1 Former Building 209

AOI 1 is Former Building 209, former fire station. Between 2000 and 2003, AFFF was used to

extinguish an intentional burn of Building 209. No information was obtained about the operations

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

209 that took 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. No remediation activities have occurred at AOI 1.

PFAS are water soluble and migrate readily to groundwater. A shallow perched aquifer underlies

the 200 Area at a depth of less than 30 feet. This shallow aquifer is hydraulically connected to the

springs (Springs 1, 2, and 3/3A) which feed the on-site ponds and are used as a potable source

of water for Camp Navajo personnel. Migration of PFAS to the regional aquifer in this area is

unlikely due to the presence of the regional aquifer and the Camp Navajo Clay confining unit. The

surface water runoff from this area enters either a series of drainage ditches that eventually

discharges off base to the north, or the stormwater system that potentially discharges to the

WWTP.

Ground-disturbing activities to surface soil at AOI 1 may result in installation worker, site worker,

off-installation residents (about 1-mile away), and visitor/trespasser exposure to potential PFAS

contamination via ingestion or inhalation of airborne particulates. Ground-disturbing activities to

subsurface soil could result in construction worker exposure to PFAS contamination via ingestion

or inhalation of airborne particulates. AOI 1 is located in the recharge area of a perched aquifer

that sits above the Navajo Clay. This clay acts as a confining unit and separates the shallow

groundwater from the deep, regional groundwater. This perched aquifer feeds springs used for

potable water at Camp Navajo. There are also domestic drinking water/public supply wells

screened at shallow depths to the north of the installation boundary. These wells are potentially

screened in the same perched aquifer. Therefore, there is a potentially complete exposure

pathway for shallow groundwater to site workers and off-installation residents. There is also the

potential for the perched aquifer to be in communication with the regional aquifer. Given the

likelihood that some surface water runoff at AOI 1 enters the stormwater system and discharges

to the WWTP holding pond, there is a potentially complete exposure pathway for surface water
PFAS Preliminary Assessment Report

Camp Navajo, Bellemont, AZ

24

and sediment to site workers, construction workers, and visitors/trespassers. The CSM for AOI 1

is shown on Figure 6-2.

6.2 AOI 2 Former Building LR200

AOI 2 is Former Building LR200, former lunch room. Between 1994 – 1999, AFFF was used to

extinguish an intentional burn of Building LR200. No remediation activities have occurred at AOI

2.

PFAS are water soluble and readily migrate to groundwater. In addition to natural springs, drinking

water at Camp Navajo is obtained from well CN-2 which is screened in the regional aquifer about

1.25-miles to the northeast (downgradient) of AOI 2 (Jacobs, 2017). An ephemeral drainage ditch

adjacent to AOI 2 drains surface water to the south.

Ground-disturbing activities to surface soil at AOI 2 may result in installation worker, site worker,

off-installation residents (about 2-miles away), and visitor/trespasser exposure to potential PFAS

contamination via ingestion or inhalation of airborne particulates. Ground-disturbing activities to

subsurface soil could result in construction worker exposure to PFAS contamination via ingestion

or inhalation of airborne particulates. Surface water at AOI 2 enters drainageways which

eventually flow to South Sink, which is believed to be a pathway to the regional aquifer (~1,500 ft

bgs). Based on the location of well CN-2, which supplies the installation with potable water,

downgradient of AOI 2 in the regional aquifer, there is a potentially complete exposure pathway

from deep groundwater to installation workers. Based on the presence of deep public supply wells

within 2-miles to the north of AOI 2, there is a potentially complete exposure pathway from deep

groundwater to off-installation residents. Based on the presence of an ephemeral drainage ditch

adjacent to AOI 2, there is a potentially complete exposure pathway from surface water and

sediment to installation workers, construction workers, and visitors/trespassers. The CSM for AOI

2 is shown on Figure 6-3.

6.3 AOI 3 Building 2

AOI 3 is Building 2, former fire station. AFFF was discharged to the environment at the former fire

station. Fire trucks and hoses were washed and flushed out in the parking lot on the north and

west sides of the building. While no specific information indicated nozzle testing at Building 2, this

was a common practice for foam-carrying trucks and possibly occurred at this location. No

remediation activities have occurred at Building 2.

PFAS are water soluble and migrate readily to groundwater. A perched aquifer underlies Building

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

feed the on-site ponds and are used as a potable source of water for Camp Navajo personnel.

Migration of PFAS to the regional aquifer in this area is unlikely due to the presence of the regional

aquifer and the Camp Navajo Clay confining unit. The surface water runoff in this area enters

storm drains which flow into enclosed pipes, and eventually exit through culverts into holding

ponds. Water fed to the holding ponds generally infiltrates or overflows into ephemeral drainage

ditches which flow to the south. The holding ponds are discussed further in Section 6.4.

Ground-disturbing activities to surface soil at AOI 3 and the holding ponds may result in installation

worker, construction worker, off-installation residents (about 3/4-mile away), and visitor/trespasser

exposure to potential PFAS contamination via ingestion or inhalation of airborne particulates.

Ground-disturbing activities to subsurface soil could result in construction worker exposure to

PFAS contamination via ingestion or inhalation of airborne particulates. Given the location of

Building 2 above the Camp Navajo Clay unit (USGS, 1987), there is the potential for PFAS
PFAS Preliminary Assessment Report

Camp Navajo, Bellemont, AZ

25

contamination in the shallow perched aquifer, which is in communication with the potable springs

and potentially shallow aquifers off-installation, via infiltration at Building 2, or at the Cantonment

Area Holding Ponds. Therefore, there is a potentially complete exposure pathway from shallow

groundwater to installation workers and off-installation residents. There is also the potential for

the perched aquifer to be in communication with the regional aquifer. Based on the stormwater

pathway to the Cantonment Area Holding Ponds, which occasionally overflow to Volunteer Wash,

there is a potentially complete exposure pathway from surface water and sediment to installation

workers, construction workers, off-installation residents, and visitors/trespassers. The CSM for

AOI 3 is shown on Figure 6-4.

6.4 AOI 4 Holding Ponds

AOI 4 is the WWTP Holding Ponds & Effluent Reuse Area. The old holding ponds are located just

to the east of the current pond. Potential secondary PFAS releases from impacted water received

at the WWTP may have occurred as a result of AFFF usage in the 200 Area. No remediation

activities have occurred at the WWTP Holding Ponds & Effluent Reuse Area.

PFAS are water soluble and migrate readily to groundwater. Since PFAS containing water from

the 200 Area may have entered the WWTP Holding Ponds & Effluent Reuse Area, PFAS may

have migrated from the surface water and sediment in the ponds to the regional aquifer.

Ground-disturbing activities to surface soil at AOI 4 may result in installation worker, construction

worker, off-installation resident (1.65-miles to the north-northeast), and visitor/trespasser

exposure to potential PFAS contamination via ingestion or inhalation of airborne soil particulates.

Ground-disturbing activities to subsurface soil could result in construction worker exposure to

potential PFAS contamination via ingestion or inhalation of airborne soil particulates. Based on

the potential for water to infiltrate to the regional aquifer, and given the presence of potable well

CN-2 downgradient, and deep public supply wells (1.5-miles to the north), there is a potentially

complete exposure pathway for groundwater to installation workers and off-installation residential

receptors. Based on the potential for PFAS to be present in the holding pond water, and for the

holding pond water to be discharged to the effluent reuse area (Figure 3-1), there is a potentially

complete exposure pathway for surface water and sediment to installation workers, construction

workers, and trespassers. The CSM for AOI 4 is shown on Figure 6-5.

6.5 AOI 5 NAAD-40

AOI 5 is the Former Sanitary Landfill (NAAD-40). Potential secondary PFAS releases from

impacted sludge brought to AOI 5 from the WWTP may have occurred. AFFF usage in the 200

Area likely resulted in flow of PFAS impacted water to the WWTP and could have led to PFAS

contamination in the WWTP sludge. No remediation activities for PFAS have occurred at NAAD40.

PFAS are water soluble and can migrate readily to groundwater. The NAAD-40 landfill is unlined; 

therefore, leaching of PFAS 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

installation which feed private potable wells. To take a conservative approach, this shallow aquifer

may also be in communication with the deep regional aquifer.

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 for PFAS contamination in surface soil and subsurface soil. Given the potential for PFAS
PFAS Preliminary Assessment Report

Camp Navajo, Bellemont, AZ

26

to have leached to the perched water table or the regional aquifer, there is the potential for multiple

residential wells off the installation which are screened in shallow and regional aquifers to be

hydraulically connected to the aquifer at NAAD-40. Therefore, there is a potentially complete

exposure pathway from groundwater to off-installation residential receptors. 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 6-6.

6.6 AOI 6 North and South Holding Ponds

AOI 6 is the North and South Cantonment Area Holding Ponds. Potential secondary PFAS

releases from impacted surface water and sediment may have occurred at the ponds. No

remediation activities have occurred at the Cantonment Area Holding Ponds.

PFAS are water soluble and readily migrate to groundwater. Since PFAS containing surface water

and sediment likely entered AOI 6 through the stormwater drains at Building 2, PFAS may have

migrated from surface water and sediment to soil and groundwater. A perched water table sits

below the Cantonment Area Holding Ponds. This shallow aquifer is potentially hydraulically

connected to the springs (Springs 1, 2, and 3/3A) which feed the on-site ponds and are used as

a potable source of water for Camp Navajo personnel.

Ground-disturbing activities to surface soil and subsurface soil at AOI 6 may result in installation

worker, construction worker, off-installation residents (0.55-miles to the north-northeast), and

visitor/trespasser exposure to potential PFAS contamination via ingestion or inhalation of airborne

soil particulates. Ground-disturbing activities to subsurface soil could result in construction worker

exposure to potential PFAS contamination via ingestion or inhalation of airborne soil particulates.

AOI 6 is located above the Camp Navajo Clay atop which sits a perched aquifer. There is the

potential for PFAS to have leached to the shallow aquifer. The shallow residential wells within 0.6-

miles to the north, and the natural springs at Camp Navajo use water from this perched aquifer

for potable purposes. Therefore, there is a potentially complete exposure pathway from shallow

groundwater to off-installation residents and installation workers. There is also the potential for

the perched aquifer to be in communication with the regional aquifer. The Cantonment Area

Holding Ponds may overflow into Volunteer Wash and eventually off-site during periods of

abnormally high surface water discharge. 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

6-7.
!5

!5

!5

!5

!5

!5

!5

!5

!5

!P

!P

!P

!P

!P

A!

A! A! A!

A!

A!

A!

A!AA!!

A!

A!

A!

A!

A!

A!

A!

A!

A!

A!A!

&<

A!

&<

A!

A!

A!

A!

A!

A!

A!

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 Ponds

Reuse Site

Buildings 333 & 334

Building K2009

Volunteer

Wash

Watershed

Government

Prairie

Watershed

Telephone

Tank

Watershed

AOI 2

AOI 3

AOI 1

AOI 5

AOI 4

AOI 6

CN-2

Spring 2

Spring 1

Spring 3

Spring 3A

C:\Users\stankevichm\OneDrive - AECOM Directory\ARNG_PFAS_GIS_60552172\MXDs\AZ\Camp_Navajo_Figures\Camp_Navajo_PA_Figures\Fig_6-1_Camp_Navajo_AOIs.mxd

0 600 1,200 2,400

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

­ Figure 6-1

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Preliminary Assessment for PFAS at Camp Navajo, AZ

9/17/2020

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Base Map: Source: Esri, Maxar, GeoEye, Earthstar Geographics, CNES/Airbus DS,

USDA, USGS, AeroGRID, IGN, and the GIS User Community

9/17/2020

1:14,400

Area of Interest

Potential PFAS Release

No Suspected Release

Facility Boundary

Water Body

Ephemeral/Intermitent Stream

Surface Water Flow Direction

Inferred Shallow Groundwater

Flow Direction

Inferred Groundwater Flow

Direction

!P Exempt Well

A! Monitoring Well

!5 Non-Exempt Well

&<

Potable Well

Areas of Interest

12420 Milestone Center Drive

Germantown, MD 20876

27
Media

SOURCE PATHWAY RECEPTOR

Former

Building

209

Controlled burn of

Building 209 was

extinguished with

AFFF. Other

potential releases

during fire station

operations.

Human

Activities

Precipitation/

Run-Off

Leaching/

Infiltration

Airborne Soil

particulate

Surface Soil

at AOI

Surface

Water/

sediment

Subsurface

Soil

Groundwater

Source Release

Mechanism Media Transportand Migration Media ExposureRoutes

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

Complete Pathway

Installation

Worker

Construction

Worker

Off-installation

Resident

Visitor/

Trespasser

Installation

Worker

Construction

Worker

Off-installation

Resident

Visitor/

Trespasser

/ / /

/ /

LEGEND

/ /

/ / /

Figure 6-2

Preliminary Conceptual Site Model – AOI 1 Former Building 209

Camp Navajo

Potential

OffInstallation

Source Not

under

Control of

ARNG

/

/

/

/ /

/

PFAS in

Surface Soil

/

/

/ /

Note: 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 is sparse and continues to be the subject of PFAS toxicological study.

28
Media

SOURCE PATHWAY RECEPTOR

AOI 2 Nozzle Testing PFAS in

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 Transportand Migration Media ExposureRoutes

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

Complete Pathway

Site

Worker

Construction

Worker Resident Trespasser/Recreational User

Site

Worker

Construction

Worker Resident Trespasser/

Recreational User

/ /

LEGEND

/ / /

/ /

/

Figure 6-3

Preliminary Conceptual Site Model

AOI 2 – OCTC Fire Station

/

/ /

/

/

/

Potential

Off-Facility

Source Not

under

Control of

ARNG

/

Note: The residential receptor refers to an off-facility receptor.

/

/ / /

/

29
Media

SOURCE PATHWAY RECEPTOR

Building 2 Truck washing and

line flushing.

Human

Activities

Precipitation/

Run-Off

Leaching/

Infiltration

Airborne Soil

particulate

Surface Soil

at AOI

Surface

Water/

sediment

Subsurface

Soil

Groundwater

Source Release

Mechanism Media Transportand Migration Media ExposureRoutes

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

Complete Pathway

Installation

Worker

Construction

Worker

Off-installation

Resident

Visitor/

Trespasser

Installation

Worker

Construction

Worker

Off-installation

Resident

Visitor/

Trespasser

/ / /

/ /

LEGEND

/ /

/ / /

Figure 6-4

Preliminary Conceptual Site Model – AOI 3 Building 2

Camp Navajo

Potential

OffInstallation

Source Not

under

Control of

ARNG

/

/

/

/ /

PFAS in

Surface Soil

& Storm

Drains

/

/

/ /

/

Note: 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 is sparse and continues to be the subject of PFAS toxicological study.

30
Media

SOURCE PATHWAY RECEPTOR

WWTP

Holding

Ponds

PFAS contaminated

water from the 200

area flows in

through storm

drains.

Human

Activities

Precipitation/

Run-Off

Leaching/

Infiltration

Airborne Soil

particulate

Surface Soil

at AOI

Surface

Water/

sediment

Subsurface

Soil

Groundwater

Source Release

Mechanism Media Transportand Migration Media ExposureRoutes

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

Complete Pathway

Installation

Worker

Construction

Worker

Off-installation

Resident

Visitor/

Trespasser

Installation

Worker

Construction

Worker

Off-installation

Resident

Visitor/

Trespasser

/ / /

/ /

LEGEND

/ /

/ / /

Figure 6-5

Preliminary Conceptual Site Model – AOI 4 WWTP Holding Ponds

Camp Navajo

Potential

OffInstallation

Source Not

under

Control of

ARNG

/

/

/

/ /

PFAS in

surface

water and

sediment

/

/

/ /

/

Note: 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 is sparse and continues to be the subject of PFAS toxicological study.

31
Media

SOURCE PATHWAY RECEPTOR

Former

Sanitary

Landfill

(NAAD-40)

PFAS leaching from

contaminated

sludge.

Human

Activities

Precipitation/

Run-Off

Leaching/

Infiltration

Airborne Soil

particulate

Surface Soil

at AOI

Surface

Water/

sediment

Subsurface

Soil

Groundwater

Source Release

Mechanism Media Transportand Migration Media ExposureRoutes

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

Complete Pathway

Installation

Worker

Construction

Worker

Off-installation

Resident

Visitor/

Trespasser

Installation

Worker

Construction

Worker

Off-installation

Resident

Visitor/

Trespasser

/

LEGEND

Figure 6-6

Preliminary Conceptual Site Model – AOI 5 Former Sanitary Landfill (NAAD-40)

Camp Navajo

Potential

OffInstallation

Source Not

under

Control of

ARNG

/

/

/

PFAS in

landfill

contents

/

/ /

/

/ / / /

/ / /

/ / /

/

Note: 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 is sparse and continues to be the subject of PFAS toxicological study.

/

32
Media

SOURCE PATHWAY RECEPTOR

Cantonment

Area

Holding

Ponds

PFAS contaminated

surface water and

sediment enters

from the stormwater

system.

Human

Activities

Precipitation/

Run-Off

Leaching/

Infiltration

Airborne Soil

particulate

Surface Soil

at AOI

Surface

Water/

sediment

Subsurface

Soil

Groundwater

Source Release

Mechanism Media Transportand Migration Media ExposureRoutes

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

Complete Pathway

Installation

Worker

Construction

Worker

Off-installation

Resident

Visitor/

Trespasser

Installation

Worker

Construction

Worker

Off-installation

Resident

Visitor/

Trespasser

/ / /

/ /

LEGEND

/ /

/ / /

Figure 6-7

Preliminary Conceptual Site Model – AOI 6 Cantonment Area Holding Ponds

Camp Navajo

Potential

OffInstallation

Source Not

under

Control of

ARNG

/

/

/

/ /

PFAS in

surface

water and

sediment

/

/

/ /

/

Note: 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 is sparse and continues to be the subject of PFAS toxicological study.

33
PFAS Preliminary Assessment Report

Camp Navajo, Bellemont, AZ

34

7. Conclusions

This PA report presents a summary of information on known or suspected PFAS releases via

management and use of AFFF at Camp Navajo. The findings presented below are based on a

site visit, interviews with Camp Navajo personnel, and records search presented in Appendix A

and Appendix B.

7.1 Findings

Six PFAS-related AOIs were identified at Camp Navajo during the PA. Section 2 and 3 discuss

areas at which suspected management and discharge of AFFF occurred. Table 7-1 summarizes

these areas and presents the rationale for their consideration as viable sources of PFAS

contamination.

Table 7-1: Camp Navajo PA AOIs

A summary of findings for this PA is shown on Figure 7-1.

Based on the documented primary and secondary PFAS releases at these AOIs, there is potential

for exposure to PFAS contamination in media at or near the facility. The preliminary CSMs for the

Potential Release

Area

Used by Determination Rationale

(AOI 1) Former Building

209

ARNG/AZARNG One suspected release A suspected discharge of AFFF

was reported during fire training

activity between 2000 and 2003.

Potential release related to

firetruck washing and hose flushing

activities may have occurred prior

to this time period while Building

209 operated as a fire station.

(AOI 2) Former Building

LR200

ARNG/AZARNG One suspected release One suspected discharge of AFFF

was reported during fire training

activity between 1994 and 1999.

(AOI 3) Building 2 ARNG/AZARNG Multiple suspected

releases

Non-fire training activities (washing

of fire trucks, flushing of hose lines,

etc) occurred outside of Building 2

from 2000 – 2012/2013.

(AOI 4) Holding Ponds ARNG/AZARNG Suspected secondary

releases

Secondary releases of PFAS

related to discharges of AFFF in

the 200 Area may have occurred.

(AOI 5) NAAD-40 ARNG/AZARNG Suspected secondary

releases

Secondary releases of PFAS

related to WWTP sludge that was

put in the landfill may have

occurred.

(AOI 6) North and

South Holding Ponds

ARNG/AZARNG Suspected secondary

releases

Secondary releases of PFAS

related to discharges of AFFF at

Building 2 may have occurred.
PFAS Preliminary Assessment Report

Camp Navajo, Bellemont, AZ

35

installation are shown on Figures 6-2 through 6-7, which present the potential receptors and

media impacted.

One other non-FTA area, which is not considered an AOI, was identified:

· Current Fire Station: The current fire station does not use AFFF. Only Class A foam is used.

A misshipment of AFFF resulted in 10-gallons being stored at the station during the PA site

visit; however, there have been no documented releases of AFFF at the station.

7.2 Uncertainties

Interviews, aerial imagery, historical records, and other information sources were evaluated during

this PA to determine the potential for PFAS-containing materials to have been present, used, or

released at the installation.

Table 7-2 summarizes the uncertainties associated with the PA:

Table 7-2: Uncertainties within the PA

Area Evaluated Source of Uncertainty

Holding Ponds Camp Navajo personnel indicated that they suspect

communication between the 200 Area stormwater system

and the WWTP. Although this communication has not

been confirmed, an increase in the WWTP’s influent has

been correlated to periods of heavy precipitation.

North and South Holding

Ponds

The amount of AFFF and concentration of PFAS in the

AFFF entering the north and south cantonment holding

ponds from the storm drains near Building 2, and

subsequently draining to the Holding Ponds is unknown; 

the number of times the holding ponds overflowed is

unknown.

Former Building LR200 Dates, durations, and volume of AFFF discharged during

fire training; concentration of PFAS in the AFFF 

discharged.

Former Building 209 Dates, durations, and volume of AFFF discharged during

fire training; concentration of PFAS in the AFFF 

discharged.

Building 2 The number of truck washing/hose flushing events is

unknown; Maintenance program for the vehicle-mounted

AFFF discharge systems is unknown; Potential storage of 

AFFF at this former fire station is unknown.

200 Area Vague and uncertain information was obtained from

interviewees regarding other potential fire training areas

near Building 209. Very little to no information is available

on these potential activities.

Current and Former Fire

Stations

The volume of AFFF managed at Camp Navajo

throughout the installation’s history is unknown.
PFAS Preliminary Assessment Report

Camp Navajo, Bellemont, AZ

36

7.3 Potential Future Actions

Interviews and records (covering 1990s to present) indicate that current or former

ARNG/AZARNG activities may have resulted in AFFF discharges or secondary PFAS releases at

the AOIs identified during the PA. Based on the CSMs developed for the AOIs, receptors have

been potentially exposed to PFAS in airborne particulates, surface and subsurface soil, surface

water, sediment, and groundwater. Table 7-3 summarizes the rationale used to determine if the

AOI should be considered for further investigation under the CERCLA process and undergo a SI.

Table 7-3: PA Findings Summary

Area of Interest AOI Location Rational Potential Future

Action

AOI 1 Former Building

209

35°13’50.6’’N,

111°50’03.2’’W

The building was intentionally burned

between 2000 – 2003 and AFFF was

most likely used to put out the fire.

Proceed to an SI.

AOI 2 Former Building

LR200

35°12’32.1’’N,

111°50’34.0’’W

The building was intentionally burned

between 1994 – 1999 and AFFF was

most likely used to put out the fire.

Proceed to an SI.

AOI 3 Building 2 35°13’41.7’’N,

111°49’19.6’’W

A leaking truck which held AFFF was

parked here. The truck was washed

and hose lines were flushed out in the

parking lot.

Proceed to an SI.

AOI 4 Holding Ponds

35°12’46.4’’N,

111°49’59.7’’W

&

35°12’42.1’’N,

111°49’51.5’’W

PFAS contaminated stormwater from

the 200 Area may have entered the

WWTP system, and discharged as

effluent to the holding ponds and

effluent reuse area.

Proceed to an SI.

AOI 5 NAAD-40 35°12’50.5’’N,

111°48’30.2’’W

PFAS contaminated sludge from the

WWTP may have been disposed of at

the NAAD-40 landfill.

Proceed to an SI.

AOI 6 North and South

Holding Ponds

35°13’34.8’’N,

111°49’07.3’’W

&

35°13’32.4’’N,

111°49’06.4’’

W

PFAS contaminated stormwater from

Building 2 may have discharged to the

north and south cantonment holding

ponds.

Proceed to an SI.

ARNG will evaluate the need for an SI at AOIs 1, 2, 3, 4, 5, and 6 at Camp Navajo based on the

potential receptors and the potential migration of PFAS contamination off the installation. ARNG

sites will be prioritized for SIs based on funding.
200 Area

Building 2

Former Building 209

Former Building LR200

North Holding Pond

South Holding Pond

NAAD-40

Holding Ponds

Reuse Site

Buildings 333 & 334

Building K2009

AOI 2

AOI 3

AOI 1

AOI 5

AOI 4

AOI 6

C:\Users\stankevichm\OneDrive - AECOM Directory\ARNG_PFAS_GIS_60552172\MXDs\AZ\Camp_Navajo_Figures\Camp_Navajo_PA_Figures\Fig_7-1_Camp_Navajo_Summary.mxd

0 600 1,200 2,400

Feet

­ Figure 7-1

CLIENT

REVISED

SCALE

PROJECT

ARNG

Preliminary Assessment for PFAS at Camp Navajo, AZ

9/17/2020

9/17/2020

9/17/2020

MS

PD

RG

GIS BY

CHK BY

PM

Base Map: Source: Esri, Maxar, GeoEye, Earthstar Geographics, CNES/Airbus DS,

USDA, USGS, AeroGRID, IGN, and the GIS User Community

9/17/2020

1:14,400

Area of Interest

Potential PFAS Release

No Suspected Release

Facility Boundary

Summary of Findings

12420 Milestone Center Drive

Germantown, MD 20876

37
PFAS Preliminary Assessment Report

Camp Navajo, Bellemont, AZ

38

8. References

Arizona Army National Guard (AZARNG). 2014. Camp Navajo Integrated Natural Resources

Management Plan (Revision).

Arizona Department of Environmental Quality (AZDEQ) (website). Verde Watershed. Retrieved

February 13, 2019 from https://legacy.azdeq.gov/environ/water/assessment/download/vrw.pdf.

Arizona Wells Registry (ADWR). February 2019. Arizona Department of Water Resources.

Retrieved February 2019 from https://gisweb2.azwater.gov/WellReg#.

Jacobs Engineering (Jacobs). 2017. Camp Navajo Vision Plan - AZARNG 2017.

National Ground Water Association (NGWA). 2018. Groundwater and PFAS: State of Knowledge

and Practice. January 2018.

Weston Solutions (Weston). January 2018a. Annual 2017 Post Closure Care Report For NAAD02 and Regional Aquifer Wells.

Weston Solutions (Weston). January 2018b. Long-Term Management Groundwater Monitoring

and Land-Use Control Report For NAAD Sites 11B, 40, 43, 01, and 20.

Tetra Tech, Inc. October 1997. Final Site Closure Report Building 2 – Fire Station.

Thorstenson, Don J. and Beard, Sue L. Geology and Fracture Analysis of Camp Navajo, Arizona

Army National Guard, Arizona. US Department of the Interior – US Geological Survey Open File

Report 98-242

U.S. Army Corps of Engineers (USACE). 30 October 2015. Five-Year Review Report.

U.S. Environmental Protection Agency (US EPA). September 1991. Guidance for Performing

Preliminary Assessments Under CERCLA.

U.S. Geological Survey (USGS). 1987. Geologic Map of the Central Part of the San Francisco

Volcanic Field, North-Central Arizona.

Wilkinson, Randall W. (August 2000) Water Resources of Bellemont Park, Coconino County,

Arizona. In Partial Fulfillment of the Requirements for the Degree of Master of Science in Geology.
PFAS Preliminary Assessment Report

Camp Navajo, Bellemont, AZ

Appendix A

Data Resources
PFAS Preliminary Assessment Report

Camp Navajo – Bellemont, Arizona

Data Resources will be provided separately on CD. Data Resources for Camp Navajo include:

Previous Investigations Completed at Camp Navajo and Surrounding Area

· 1997 Final Site Closure Report, Building 2 – Fire Station

· 2013 Camp Navajo Integrated Natural Resources Management Plan (Revision), Bellemont,

Arizona

· 2018 Final Long-Term Management Groundwater Monitoring and Land-Use Control Report

For NAAD Sites 11B, 40, 43, 01, and 20 at Camp Navajo, Coconino County, Arizona

· 2018 Final Annual 2017 Post Closure Care Report For NAAD-02 and Regional Aquifer

Wells at Camp Navajo, Coconino County, Arizona

· 2000 Water Resources of Bellemont Park, Coconino County, Arizona

· 2015 Five Year Review Report – U.S. Army Corps of Engineers

Camp Navajo EDRTM Report

· 2019 Camp Navajo Environmental Data Resources, Inc.TM Report

Additional Resources

· 1987 Geologic Map of the Central Part of the San Francisco Volcanic Field, North-Central

Arizona – USGS

· 1998 Geology and Fracture Analysis of Camp Navajo, Arizona Army National Guard – US

Geological Survey

· Arizona Wells Registry – Arizona Department of Water Resources
PFAS Preliminary Assessment Report

Camp Navajo, Bellemont, AZ

Appendix B

Preliminary Assessment Documentation
PFAS Preliminary Assessment Report

Camp Navajo, Bellemont, AZ

Appendix B.1

Interview Records

















PFAS Preliminary Assessment Report

Camp Navajo, Bellemont, AZ

Appendix B.2

Visual Site Inspection Checklists












PFAS Preliminary Assessment Report

Camp Navajo, Bellemont, AZ

Appendix B.3

Conceptual Site Model Information
Preliminary Assessment – Conceptual Site Model Information

Site Name: Camp Navajo

Why has this location been identified as a site?

Documented releases of AFFF

Are there any other activities nearby that could also impact this location?

None identified

Training Events

Have any training events with AFFF occurred at this site? Yes

If so, how often? A few instances of controlled structure burns using AFFF

How much material was used? Is it documented? Not sure how much used. Not documented.

Identify Potential Pathways: Do we have enough information to fully understand over land surface 

water flow, groundwater flow, and geological formations on and around the facility? Any direct 

pathways to larger water bodies?

Surface Water:

Surface water flow direction? Varies across the site. Watershed drains to the south.

Average rainfall? 20.16’’

Any flooding during rainy season? No

Direct or indirect pathway to ditches? Yes

Direct or indirect pathway to larger bodies of water? Yes. Eventual drainage to Volunteer Wash.

Does surface water pond any place on site? No natural ponding.

Any impoundment areas or retention ponds? Yes. Near the springs, WWTP, and Cantonment Area.

Any NPDES location points near the site? No

How does surface water drain on and around the flight line? N/A
Preliminary Assessment – Conceptual Site Model Information

Groundwater:

Groundwater flow direction? Variable. Regional flow toward north.

Depth to groundwater? Variable. Perched aquifers and regional aquifer. Varies 100 ft – 1,700 ft bgs.

Uses (agricultural, drinking water, irrigation)? One drinking water well on-site.

Any groundwater treatment systems? No.

Any groundwater monitoring well locations near the site? Yes, many monitoring wells on-site.

Is groundwater used for drinking water? Yes

Are there drinking water supply wells on installation? Yes

Do they serve off-post populations? No

Are there off-post drinking water wells downgradient ?

Exempt wells down-gradient of assumed regional GW flow to the north of the base. Exempt wells down 

gradient of surface water flow to the south of the base.

Waste Water Treatment Plant:

Has the installation ever had a WWTP, past or present? Yes, currently.

If so, do we understand the process and which water is/was treated at the plant? Unsure whether water 

from the 200 area drains to WWTP or not. 

Do we understand the fate of sludge waste? Sent to on-site landfill from 1966-1981

Is surface water from potential contaminated sites treated?

Domestic and industrial wastewater generated at Camp Navajo is treated there.

Equipment Rinse Water

1. Is firefighting equipment washed? Where does the rinse water go?

Truck and hose lines containing AFFF were washed in parking lot of Bldg 2 – Former Fire Station. Water 

likely went into storm drain which empty into Cantonment Area holding ponds.

2. Are nozzles tested? How often are nozzles tested? Where are nozzles tested? Are nozzles cleaned after 

use? Where does the rinse water flow after cleaning nozzles?

N/A

3. Other?
Preliminary Assessment – Conceptual Site Model Information

Identify Potential Receptors:

Site Worker Yes

Construction Worker Yes

Recreational User N/A

Residential Yes

Child Residential

Ecological Yes. Surface water.

Note what is located near by the site (e.g. daycare, schools, hospitals, churches, agricultural, livestock)?

Large residential neighborhood to the north. Shuff Steel Co to the north. Some residences and business to 

the west and east of site boundaries. 

Documentation

Ask for Engineering drawings (if applicable).

Has there been a reconstruction or changes to the drainage system? When did that occur?

None reported
PFAS Preliminary Assessment Report

Camp Navajo, Bellemont, AZ

Appendix C

Photographic Log
PreliminaryAssessment Report

AECOM

Camp Navajo

Perfluorooctane-Sulfonic Acid (PFOS) and 

Perfluorooctanoic Acid (PFOA) Impacted Sites 

ARNG Installations, Nationwide

APPENDIX C – Photographic Log

Army National Guard, Preliminary 

Assessment for PFAS Camp Navajo Bellemont, Arizona

Description:

Building 2 east elevation

(view to W)

Photograph No. 1

Description:

Building 2 and storm drain

(view to S)

Photograph No. 2
AECOM

Preliminary Assessment Report 

Camp Navajo

Perfluorooctane-Sulfonic Acid (PFOS) and 

Perfluorooctanoic Acid (PFOA) Impacted Sites 

ARNG Installations, Nationwide

APPENDIX C – Photographic Log

Army National Guard, Preliminary 

Assessment for PFAS Camp Navajo Bellemont, Arizona

Description:

Building 2 west elevation

(view to SE)

Photograph No. 3

Description:

AFFF (6%) in storage in 

current Fire Station

(view is S)

Photograph No. 4
AECOM

Preliminary Assessment Report 

Camp Navajo

Perfluorooctane-Sulfonic Acid (PFOS) and 

Perfluorooctanoic Acid (PFOA) Impacted Sites 

ARNG Installations, Nationwide

APPENDIX C – Photographic Log

Army National Guard, Preliminary 

Assessment for PFAS Camp Navajo Bellemont, Arizona

Description:

Label for AFFF

(view to S)

Photograph No. 5

Description:

Eastern holding ponds 

(southern-most)

(view to SE)

Photograph No. 6
AECOM

Preliminary Assessment Report 

Camp Navajo

Perfluorooctane-Sulfonic Acid (PFOS) and 

Perfluorooctanoic Acid (PFOA) Impacted Sites 

ARNG Installations, Nationwide

APPENDIX C – Photographic Log

Army National Guard, Preliminary 

Assessment for PFAS Camp Navajo Bellemont, Arizona

Description:

Eastern holding ponds 

(northern-most)

(view to NE)

Photograph No. 7

Description:

200 Area

Photograph No. 8
AECOM

Preliminary Assessment Report 

Camp Navajo

Perfluorooctane-Sulfonic Acid (PFOS) and 

Perfluorooctanoic Acid (PFOA) Impacted Sites 

ARNG Installations, Nationwide

APPENDIX C – Photographic Log

Army National Guard, Preliminary 

Assessment for PFAS Camp Navajo Bellemont, Arizona

Description:

Area of Springs

Photograph No. 9

Description:

Landfill

Photograph No. 10
AECOM

Preliminary Assessment Report 

Camp Navajo

Perfluorooctane-Sulfonic Acid (PFOS) and 

Perfluorooctanoic Acid (PFOA) Impacted Sites 

ARNG Installations, Nationwide

APPENDIX C – Photographic Log

Army National Guard, Preliminary 

Assessment for PFAS Camp Navajo Bellemont, Arizona

Description:

LR200

Photograph No. 11

Description:

Road to 200 Area

Photograph No. 12