FINAL

Preliminary Assessment Report

Cheyenne Army Aviation Support 

Facility

Las Vegas, Nevada

Perfluorooctanesulfonic Acid (PFOS) and Perfluorooctanoic 

Acid (PFOA) Impacted Sites

ARNG Installations, Nationwide

July 2020

Prepared for:

Army National Guard Bureau

111 S. George Mason Drive

Arlington, VA 22204

UNCLASSIFIED
PFAS Preliminary Assessment Report

Cheyenne Army Aviation Support Facility Las

Vegas, Nevada

i

Table of Contents

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

1. Introduction ........................................................................................................................ 4

1.1 Authority and Purpose .............................................................................................. 4

1.2 Preliminary Assessment Methods ............................................................................. 4

1.3 Report Organization .................................................................................................. 5

1.4 Facility Location and Description............................................................................... 5

1.5 Facility Environmental Setting ................................................................................... 6

1.5.1 Geology ......................................................................................................... 6

1.5.2 Hydrogeology ................................................................................................. 6

1.5.3 Hydrology ....................................................................................................... 7

1.5.4 Current and Future Land Use ......................................................................... 7

1.5.5 Climate ........................................................................................................... 7

2. Fire Training Areas ........................................................................................................... 12

3. Non-Fire Training Areas ................................................................................................... 14

3.1 Hangar 1 ................................................................................................................. 14

4. Emergency Response Areas ............................................................................................ 16

5. Adjacent Sources ............................................................................................................. 17

5.1 North Las Vegas Airport .......................................................................................... 17

6. Preliminary Conceptual Site Model .................................................................................. 19

6.1 AOI 1: Hangar 1 and Helipad Area .......................................................................... 19

7. Conclusions ..................................................................................................................... 22

7.1 Findings .................................................................................................................. 22

7.2 Uncertainties ........................................................................................................... 22

7.3 Potential Future Actions .......................................................................................... 23

8. References ...................................................................................................................... 25
PFAS Preliminary Assessment Report

Cheyenne Army Aviation Support Facility Las

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Figures

Figure ES-1 Summary of Findings.

Figure ES-2 Preliminary Conceptual Site Model for AOI 1

Figure 1-1 Facility Location

Figure 1-2 Groundwater Features

Figure 1-3 Surface Water Features

Figure 2-1 Fire Training Area

Figure 3-1 Non-Fire Training Areas

Figure 5-1 Adjacent Source

Figure 6-1 Area of Interest

Figure 6-2 Preliminary Conceptual Site Model for AOI 1

Figure 7-1 Summary of Findings

Tables

Table ES-1: Areas of Interest

Table 7-1: Areas of Interest

Table 7-2: No Suspected Release Areas

Table 7-3: Sources of Uncertainties

Table 7-4: PA Findings Summary

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
PFAS Preliminary Assessment Report

Cheyenne Army Aviation Support Facility Las

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Acronyms and Abbreviations

AASF Army Aviation Support Facility

AECOM AECOM Technical Services, Inc.

AFFF aqueous film forming foam

AOI

ARNG

Area of Interest

Army National Guard

bgs below ground surface

CERCLA

CFR

Comprehensive Environmental Response, Compensation, and

LiabilityAct

Code of Federal Regulations

CSM conceptual site model

EDRTM Environmental Data Resources, Inc. TM

°F degrees Fahrenheit

FTA Fire Training Areas

HA Health Advisory

NVARNG Nevada Army National Guard

PA Preliminary Assessment

PFAS per- and poly-fluoroalkyl substances

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

SI Site Inspection

US United States

USACE United States Army Corps of Engineers

UCMR3 Unreguated Contaminant Monitoring Rule 3

USDA United States Department of Agriculture

USGS United States Geological Survey

USEPA United States Environmental Protection Agency
PFAS Preliminary Assessment Report

Cheyenne Army Aviation Support Facility Las

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Executive Summary

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

Inspections (SIs) for Perfluorooctanesulfonic acid (PFOS) and Perfluorooctanoic acid (PFOA)

Impacted Sites at ARNG Facilities Nationwide. A PA for per- and polyfluoroalkyl substances

(PFAS)-containing materials was completed for Cheyenne Army Aviation Support Facility (AASF; 

also referred to as the “facility”) in Las Vegas, Nevada, to identify areas of known or suspected

releases known as Areas of Interest (AOIs) and possible exposure pathways to receptors. The

PA included the following tasks:

· Reviewed available administrative record documents and Environmental Data Resources,

Inc. (EDR)TM report packages to obtain information relevant to potential PFAS releases, such

as: drinking water well locations, historical aerial photographs, Sanborn maps, and

environmental compliance actions in the area surrounding the facility; 

· Conducted a 1-day PA site visit on 20 September 2019 and completed visual site inspections

at locations where PFAS-containing materials were suspected of being stored, used, or

disposed;

· Interviewed current AASF Nevada ARNG (NVARNG) personnel during the site visit and

NVARNG environmental managers and operations staff;

· Identified AOIs and developed a preliminary conceptual site model (CSM) to summarize

potential source-pathway-receptor linkages of potential PFAS in soil, groundwater, surface

water, and sediment for each AOI.

One AOI related to a PFAS release was identified at the Cheyenne AASF, based on PA data. The

AOI is shown on Figure ES-1 and described in the Table ES-1 below:

Table ES-1: Areas of Interest

Area of Interest Name Used by Potential Release Dates

AOI 1 Hangar 1 and Helipad Area NVARNG Prior to 2003

Based on the potential for AFFF release at this AOI, there is potential for exposure to PFAS

contamination in airborne soil particulate and surface soils to trespassers, site and construction

workers via inhalation and ingestion, and in subsurface soil to construction workers. Groundwater

is an incomplete pathway; the city pulls only 10% of its water from deeper aquifers that are

protected by an aquitard. Based on the United States (US) Environmental Protection Agency

(USEPA) Unregulated Contaminant Monitoring Rule 3 (UCMR3) data, it was indicated that no

PFAS were detected in a public water system above the USEPA lifetime Health Advisory within

20 miles of the facility. The HA is 70 parts per trillion for PFOA and PFOS, individually or combined.

PFAS analyses performed in 2016 had method detection limits that were higher than currently

achievable. Thus, it is possible that low concentrations of PFAS were not detected during the

UCMR3 but might be detected if analyzed today.

One adjacent off-facility potential PFAS release area was identified, which includes an emergency

response area from a plane crash in 2013. As a result of adjacent PFAS releases, it is possible

PFAS are in site media surrounding the AASF. The preliminary conceptual site model for the

NVARNG Cheyenne AASF is shown on Figure ES-2.
North Las

Vegas

Airport

0 700 1,400 2,800

Feet

Legend

Area of Interest

Potential PFAS Release

Facility Boundary

Wetland

River/Stream

CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

HO

MW

3/12/2020

3/12/2020

NOTES Preliminary Assessment for PFAS at AASF Las Vegas Cheyenne

3/12/2020 ­ Figure ES-1 PM RG 3/12/2020

Q:\Projects\ENV\GEARS\GEO\ARNG PFAS\900-CAD-GIS\920-GIS or Graphics\MXD\NV\CheyenneAASF\FigES-1_CheyenneAASF_Summary - Copy.mxd

12420 Milestone Center Drive

Germantown, MD 20876

Summary of Findings

Base Map: Source: Esri, DigitalGlobe, GeoEye,

Earthstar Geographics, CNES/Airbus DS, USDA, USGS,

1:16,800

Possible FTA

Trimax Storage 

Area Trimax Storage 

Area

AOI 1

0 75 150 300

Feet

2
Media

SOURCE PATHWAY RECEPTOR

AOI 1 –

Hangar 1 

and Helipad 

Area

Possible 

AFFF release 

from 

discharge of 

fire 

extinguisher

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 Transport and Migration Media Exposure Routes

Inhalation of 

Dust

Ingestion

Ingestion

Ingestion

Ingestion

Human Receptors: 

Current/ Future

Flow-Chart Continues

Partial / Possible Flow

Incomplete Pathway

Potentially Complete Pathway

Complete Pathway

Site 

Worker

Construction 

Worker Resident

Site 

Worker

Construction 

Worker Resident

/ / / /

/ / /

LEGEND

/ / / /

/ / / /

/ / / /

Figure ES-2

Preliminary Conceptual Site Model

Cheyenne AASF, Las Vegas, NV

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

Trespasser

Trespasser

Notes:

1. The resident and recreational user

receptors refer to an off-site resident and

recreational user.

2. Dermal contact exposure pathway is 

incomplete for PFAS.

Flow-Chart Stops

/

3
PFAS Preliminary Assessment Report

Cheyenne Army Aviation Support Facility Las

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1. Introduction

1.1 Authority and Purpose

The Army National Guard (ARNG) G9 is the lead agency in performing Preliminary Assessments

(PAs) and Site Inspections (SIs) for Perfluorooctanesulfonic acid (PFOS) and Perfluorooctanoic

acid (PFOA) at Impacted Sites at ARNG Facilities Nationwide. This work is supported by the

United States (US) Army Corps of Engineers (USACE) Baltimore District and their contractor

AECOM Technical Services, Inc. (AECOM) under Contract Number W912DR-12-D-0014, Task

Order W912DR17F0192, issued 11 August 2017.

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) released as part of firefighting activities, although other

PFAS sources are possible. In addition, the ARNG is assessing businesses or operations adjacent

to the ARNG facility (not under the control of ARNG) that could potentially be responsible for a

PFAS release.

PFAS are classified as emerging environmental contaminants that are garnering increasing

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

formulations contain highly diverse mixtures of compounds. Thus, the fate of PFAS compounds

in the environment varies. The regulatory framework at both federal and state levels continues to

evolve. The US Environmental Protection Agency (USEPA) issued lifetime Drinking Water Health

Advisories (HAs) for PFOA and PFOS in May 2016, but there are currently no promulgated

national standards regulating PFAS in drinking water. The HA is 70 parts per trillion for PFOA and

PFOS, individually or combined.

This document presents the findings of a PA for PFAS-containing materials at the current

Cheyenne Army Aviation Support Facility Las Vegas (AASF; also referred to as the “facility”),

Nevada, 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 [CFR] Part 300), and Army requirements and

guidance.

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

may have been released into the environment at the AASF. The term PFAS will be used

throughout this report to encompass all PFAS chemicals being evaluated, including PFOS and

PFOA, which are key components of AFFF. If a known or suspected discharge of AFFF or other

PFAS-containing material has occurred, that location is designated an Area of Interest (AOI).

1.2 Preliminary Assessment Methods

The following tasks were performed as part of this PA included the following tasks:

· Reviewed available administrative record documents and Environmental Data Resources,

Inc. (EDR)TM report packages to obtain information relevant to potential PFAS releases, such

as: drinking water well locations, historical aerial photographs, Sanborn maps, and

environmental compliance actions in the area surrounding the facility; 

· Conducted a 1-day PA site visit on 20 September 2019 and completed visual site inspections

at locations where PFAS-containing materials were suspected of being stored, used, or

disposed;
PFAS Preliminary Assessment Report

Cheyenne Army Aviation Support Facility Las

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· Interviewed current AASF Nevada ARNG (NVARNG) personnel during the site visit and

NVARNG environmental managers and operations staff;

· Identified AOIs and developed a preliminary conceptual site model (CSM) to summarize

potential source-pathway-receptor linkages of potential PFAS in soil, groundwater, surface

water, and sediment for each AOI.

1.3 Report Organization

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

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

of each are as follows:

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

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

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

visit;

· Section 3 – Non-Fire Training Areas: describes other locations of suspected PFAS releases

at the facility identified during the site visit;

· Section 4 – Emergency Response Areas: describes areas of suspected AFFF discharge

at the facility, specifically in response to emergency situations;

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

the facility that are not under the control of ARNG;

· Section 6 – Preliminary Conceptual Site Model: describes the pathways of suspected

PFAS transport and receptors at the facility;

· Section 7 – Conclusions: summarizes the data 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 Facility Location and Description

Cheyenne AASF is located in the city of North Las Vegas, about 5 miles northwest of downtown

Las Vegas, Nevada. The AASF occupies a small portion of the Cheyenne Air Center that is located

on the north edge of the North Las Vegas Airport (Figure 1-1). The Cheyenne Air Center is a

privately-owned company servicing private air planes, as well as some aviation tour companies.

The AASF includes the use of a part of a large building that is divided in two adjoining pieces:

Hangar 1 and Hangar 2. Hangar 1 is leased to the Rochelle Aizenberg Revocable Trust and then,

starting in 2018, subleased to the NVARNG. Hangar 2 is leased to NVARNG by a private owner

per a 2018 agreement (Broadbent & Associates, 2019). The lease agreements can be found in

Appendix A.
PFAS Preliminary Assessment Report

Cheyenne Army Aviation Support Facility Las

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1.5 Facility Environmental Setting

The AASF is located in the southern tip of Nevada at an elevation of approximately 2,205 feet

above mean sea level. The facility is covered by the US Geological Survey (USGS) Las Vegas

NW 7.5-minute quadrangle topographic map. The facility is developed with two hangars, concrete,

and asphalt features.

The facility and city of North Las Vegas is located within the Las Vegas Valley, which is a faultbounded structural hydrologic basin made of alluvial-fan deposits. The Las Vegas Valley is part

of the Mojave Desert and is about 1,600 square miles except for its the northwest portion that

consists of foothills or mountain ranges. (Bell, 2016).

1.5.1 Geology

Cheyenne AASF is located in the Basin and Range geomorphic province, where east-west

extensional tectonic movement (spreading) has created a large number of north-south oriented

block faulted mountain ranges. The area is situated in the southern part of the Las Vegas Valley,

which is northwest trending, generally following the right lateral strike-slip character of the Las

Vegas shear zone. This fault cuts the thrust system at right angles, offsetting the southern tier of

mountains to the west. The Las Vegas Valley itself has been formed by the pulling apart of block

faulted ranges by drag effects of displacements along the Las Vegas shear zone (Wyman et al,

1993).

The Las Vegas Valley is a fault-bounded structural and hydrologic basin containing hundreds of

feet of late Tertiary and Quaternary lacustrine, paludal, and alluvial deposits. These sediments

consist of poorly compressible, coarse-grained alluvial-fan deposits around the valley margins

and of highly compressible, fine-grained sediment in the middle of the valley (Bell, 2016). The Las

Vegas Valley drains into Lake Mead via the Las Vegas Wash and is part of the overall Colorado

River drainage system. A low divide north of Las Vegas separates the main part of the valley from

the interior draining basins to the north. The valley lies between the Spring Mountains to the west,

which reach an altitude of 12,000 feet, and the much lower Frenchman (4,000 feet) and Sheep

Mountains and Las Vegas Ranges (10,000 feet) to the east.

1.5.2 Hydrogeology

The Las Vegas Valley is underlain by coalescing alluvial fans mostly originating on the front of the

Spring Mountains and Sheep Range. These fans contain lenticular and irregularly distributed

aquifers of permeable sand and gravel, separated by aquitards of silt and clay that are nearly

impermeable, created a large artesian ground-water system (Wyman et al, 1993).

The facility is underlain by silt with discrete layers of sand, clay, or gravel. Based on the soil

survey published by the US Department of Agriculture (USDA) Soil Conservation Service, the

facility encompasses one mapped soil unit, Skyhaven, which is a very fine sandy loam. The

facility’s hydrologic soil group classification is “Class C, slow infiltration rates, soils with layers

impeding downward movement of water or soils with moderately fine or fine textures,” (Broadbent

& Associates, 2019). The soil drainage classification is “well drained,” (Broadbent & Associates,

2019). Depth to groundwater is expected to be approximately 20 feet below ground surface (bgs),

based on information from the Nevada Division of Water Resources on-line Well Log Database

(Broadbent & Associates, 2019). The groundwater flow direction in the vicinity of the facility is

assumed to be toward the southeast (Broadbent & Associates, 2019). Southern Nevada gets

roughly 10% of its water supply from groundwater. The Las Vegas Valley Water District pumps
PFAS Preliminary Assessment Report

Cheyenne Army Aviation Support Facility Las

Vegas, Nevada

7

groundwater from wells to meet peak summer demand. During the hot summer months from June

through September, groundwater can account for up to 25% of the valley's daily water supplies

(Las Vegas Valley Water District [LVVWD], 2019).

Groundwater in the Las Vegas Valley comes from three major primary aquifer zones generally

located from 300 to 1,500 feet below land surface. Thick layers of clay and fine-grained sediment

separate these primary aquifers from the shallow aquifers, which lie within 50 feet bgs. All

groundwater in the Las Vegas Valley comes from the snowmelt and rainfall from mountain ranges

surrounding the valley. Most of the wells in the Las Vegas area draw water from the primary

principal aquifer system, which is several hundred feet thick. This aquifer system is confined by

an aquitard, which is about 200 feet thick (Las Vegas Valley Groundwater Management Program

[GMP], 2019).

An EDRTM report conducted a well search for a 1-mile radius surrounding the facility (Appendix

A). Using additional online resources, such as state and local GIS databases, wells were

researched to a 4-mile radius of the facility. No on-site water wells or springs exist on the facility

(Figure 1-2).

1.5.3 Hydrology

The topography in the area of the AASF is relatively flat, and surface water generally drains

towards the southeast. No lakes, ponds, streams, retentions basins, or areas of standing water

are located on or immediately adjacent to the facility.

The western edge of the Las Vegas Valley is located approximately 5 miles west of Lake Mead

and serves as an impoundment on the Colorado River. Most shallow groundwater and all surface

water in the western Las Vegas Valley are tributaries of the Colorado River via the Las Vegas

Wash. According to LVVWD, less than 2% of Lake Mead’s water come from the Las Vegas Wash,

and the remaining water is sourced from snowmelt into the Colorado River. Southern Nevada gets

nearly 90% of its water from the Colorado River, which begins as snowmelt in the Rocky

Mountains, and ends up in Lake Meade (LVVWD, 2019). Water features near the facility are

shown in Figure 1-3.

Based on the USEPA Unregulated Contaminant Monitoring Rule 3 (UCMR3) data, it was indicated

that no PFAS were detected in a public water system above the HA within 20 miles of the facility.

The HA is 70 parts per trillion for PFOA and PFOS, individually or combined. PFAS analyses

performed in 2016 had method detection limits that were higher than currently achievable. Thus,

it is possible that low concentrations of PFAS were not detected during the UCMR3 but might be

detected if analyzed today.

1.5.4 Current and Future Land Use

Presently, Cheyenne AASF resides in Cheyenne Air Center. The AASF facility includes a portion

of a large building (Hangars 1 and 2 including an office area), three helicopter landing pads, and

a small paved area. The current land use is listed as M-2 General Industrial. Future land use is

not anticipated to change (Broadbent & Associates, 2019).

1.5.5 Climate

The facility lies in a relatively high-altitude portion of the Mojave Desert, with a subtropical hotdesert climate (Skrbac, 2005). Summers display classic desert southwest characteristics with

low humidity and daily high temperatures typically exceeding 100 degrees Fahrenheit (oF) and
PFAS Preliminary Assessment Report

Cheyenne Army Aviation Support Facility Las

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lows around 70 oF. Winters are mostly mild. The Las Vegas region generally receives less than 5

inches of rainfall per year (National Oceanic and Atmospheric Administration [NOAA] 2019).
Army Aviation

Support Facility

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NOTES Preliminary Assessment for PFAS at AASF Las Vegas Cheyenne

12/6/2019 ­ Figure 1-1

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NOTES Preliminary Assessment for PFAS at AASF Las Vegas Cheyenne

1/22/2020 ­ Figure 1-2 PM RG 1/22/2020

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12420 Milestone Center Drive

Germantown, MD 20876

Groundwater Features

Base Map: Source: Esri, DigitalGlobe, GeoEye,

Earthstar Geographics, CNES/Airbus DS, USDA, USGS,

1:31,680

10
Box Canyon-Las

Vegas Wash

Watershed

City of Las

Vegas-Las Vegas

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12/6/2019 ­ Figure 1-3

PM RG 12/6/2019

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12420 Milestone Center Drive

Germantown, MD 20876

Surface Water Features

Base Map: Source: Esri, DigitalGlobe, GeoEye,

Earthstar Geographics, CNES/Airbus DS, USDA, USGS,

1:31,680

11
PFAS Preliminary Assessment Report

Cheyenne Army Aviation Support Facility Las

Vegas, Nevada

12

2. Fire Training Areas

One possible FTA was identified during the PA. According to interviews conducted with facility

personnel whose collective knowledge spans from 2003 to present, and historical research, fire

training did not regularly occur on site. In the event of an emergency, 911 is called, and the North

Las Vegas Fire Department responds.

Personnel had anecdotal knowledge that a fire extinguisher may have been discharged by a

guardsman on the unpaved sandy area at the southwest edge of the asphalt helipads as part of

an unofficial training exercise. Interviewees believe that dawn dish soap was likely used if this

was the case, but there is no documentation to confirm this (Figure 2-1). A specific timeframe for

this event was not given; however, personnel indicated it would have been prior to 2003, before

any of the interviewees were stationed at this AASF. Because details are not specifically recalled,

this training event is considered a potential AFFF release. A polymer coating and drainage swale

which runs south underneath the adjacent access road into an empty soil patch was added to this

area in 2016 to reduce the spread of dust during helicopter take-off and landings. Interview

records appear in Appendix B.
Possible FTA

0 100 200 400

Feet

Legend

Potential PFAS Release

Facility Boundary

Wetland

River/Stream

CLIENT

REVISED

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12420 Milestone Center Drive

Germantown, MD 20876

Fire Training Areas

Base Map: Source: Esri, DigitalGlobe, GeoEye,

Earthstar Geographics, CNES/Airbus DS, USDA, USGS,

1:2,400

13
PFAS Preliminary Assessment Report

Cheyenne Army Aviation Support Facility Las

Vegas, Nevada

14

3. Non-Fire Training Areas

In addition to FTAs, the PA evaluated areas where PFAS-containing materials may have been

broadly used, stored, or disposed. This may include buildings with fire suppression systems, paint

booths, AFFF storage areas, and areas of compliance demonstrations. Information on these

features obtained during the PA are included in Appendices A and B. One non-FTA where AFFF

has previously been or is currently being stored was identified during the PA. A description of the

non-FTA is presented below, and the non-FTA is shown on Figure 3-1. Interview records with

relevant information appear in Appendix B, and photographs appear in Appendix C.

3.1 Hangar 1

Hangar 1 formerly housed a single Tri-MaxTM hand-truck that was stored in various locations

around the structure. The two primary storage areas are shown in Figure 3-1. This Tri-MaxTM unit

was on site from the early 2000s until 2016, when it was sent back to the Carson City Warehouse

Defense Reutilization and Marketing Office. The unit was regularly serviced by a safety officer in

Reno contracted through ABC until sometime between 2008 and 2010. According to interviews,

there are no records or recollection of the hand-truck ever being used for fire training or

emergency response.

Presently, one fire extinguisher containing AFFF exists on site. The extinguisher is regularly

inspected and maintained, and it is in good condition. According to personnel interviews, the unit

is stored just outside of Hangar 1, near the helipad area (area not shown in Figure 3-1).

Photographs of the fire extinguishers at the facility appear in Appendix C.

Given the existence of AFFF at the facility, there is a potential for an undocumented release from

the former Tri-MaxTM unit or existing fire extinguisher.
Trimax

Storage

Area

Trimax

Storage

Area

0 100 200 400

Feet

Legend

Potential PFAS Release

Facility Boundary

Wetland

River/Stream

CLIENT

REVISED

SCALE

ARNG

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12420 Milestone Center Drive

Germantown, MD 20876

Non-Fire Training Areas

Base Map: Source: Esri, DigitalGlobe, GeoEye,

Earthstar Geographics, CNES/Airbus DS, USDA, USGS,

1:2,400

15
PFAS Preliminary Assessment Report

Cheyenne Army Aviation Support Facility Las

Vegas, Nevada

16

4. Emergency Response Areas

No emergency response areas were identified within the boundaries of the AASF facility during

the PA through interviews, previous investigations, online research, and the EDRTM report

(Appendix A). Personnel Interviewed during the PA site visit stated that no incidents have

occurred on site that required fire suppression (Appendix B), and the City of North Las Vegas

Fire Department provides emergency response to Cheyenne AASF.
PFAS Preliminary Assessment Report

Cheyenne Army Aviation Support Facility Las

Vegas, Nevada

17

5. Adjacent Sources

One off-facility site was identified as a possible PFAS source adjacent to Cheyenne AASF during

the PA and is discussed below. Figure 5-1 presents the location of the suspected adjacent PFAS

sources.

5.1 North Las Vegas Airport

The North Las Vegas Airport opened as Sky Haven Airport on 7 December 1941. Ownership

changed at Sky Haven several times, including changing the name to North Las Vegas Airport

(Clark County Department of Aviation, 2016). Interviews with NVARNG facility staff and a historical

records search revealed little information regarding use of AFFF at North Las Vegas Airport.

During a records search, it was found that an emergency incident happened on or near the runway

on January 02, 2013. According to the National Transportation Safety Board, a twin-engine Piper

Aerostar crashed and burst into flames at the airport following a hard landing. It is unknown if

AFFF was used as part of the emergency response to the fire (National Transportation Safety

Board [NTSB], 2015).
Possible FTA

North Las

Vegas

Airport

0 700 1,400 2,800

Feet

Legend

Potential PFAS Release

Facility Boundary

Wetland

River/Stream

CLIENT

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12420 Milestone Center Drive

Germantown, MD 20876

Adjacent Sources

Base Map: Source: Esri, DigitalGlobe, GeoEye,

Earthstar Geographics, CNES/Airbus DS, USDA, USGS,

1:16,800

18
PFAS Preliminary Assessment Report

Cheyenne Army Aviation Support Facility Las

Vegas, Nevada

19

6. Preliminary Conceptual Site Model

Based on the PA findings, one potential release area was identified at Cheyenne AASF or adjacent

areas as a result of NVARNG actions and will be considered an AOI. The AOI locations is shown

on Figure 6-1. A CSM includes three components necessary for potentially complete exposure

pathways related to a site: (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 practice suggests it is a negligible

pathway compared to ingestion; however, exposure data for dermal pathways are sparse and

continue to be the subject of PFAS toxicological study. Receptors for Cheyenne AASF include site

workers, construction workers, off-site residents, and trespassers. The CSM indicates which

specific receptors could potentially be exposed to PFAS.

6.1 AOI 1: Hangar 1 and Helipad Area

AOI 1 encompasses Hangar 1 where a Tri-MaxTM hand-truck was stored for approximately 16

years and where a current AFFF fire extinguisher is kept. If AFFF were discharged from either

item, residual material could be washed from the hanger and into surrounding soil areas. AOI1

also includes the helipad area where a fire extinguisher possibly containing AFFF may have once

been discharged into the adjacent unpaved soil (Figure 6-1).

Ground disturbing activities in the area could result in construction worker, site worker, and

trespasser exposure to potential PFAS contamination via inhalation of dust or ingestion of surface

soil, as well as construction worker to subsurface soil. Accidental ingestion of surface water is not

considered a potentially complete pathway for any receptor because surface water is limited to

times of rare rainfall events.

PFAS are water soluble and can migrate readily from soil to groundwater. Groundwater beneath

the facility is approximately 20 feet bgs. The City of Las Vegas’s primary drinking water source is

the Colorado River, but Las Vegas supplements about 10% of its supply from groundwater

resources in the area obtained from the deeper aquifers protected by an aquitard. It is unlikely

that groundwater is a complete exposure pathway. The preliminary CSM for AOI 1 is shown on

Figure 6-2.
Trimax Storage

Area

Trimax

Storage

Area

Possible FTA

City of Las

Vegas-Las Vegas

Wash Watershed

AOI 1

0 100 200 400

Feet

Legend

Area of Interest

Potential PFAS Release

No Suspected PFAS

Release

Facility Boundary

Wetland

River/Stream

CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

SK

MW

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3/6/2020 ­ Figure 6-1

PM RG 3/6/2020

\\URSGermantown.us.ie.urs\Germantown\Projects\ENV\GEARS\GEO\ARNG PFAS\900-CAD-GIS\920-GIS or Graphics\MXD\NV\CheyenneAASF\Fig6-1_CheyenneAASF_AOIs.mxd

12420 Milestone Center Drive

Germantown, MD 20876

Areas of Interest

Base Map: Source: Esri, DigitalGlobe, GeoEye,

Earthstar Geographics, CNES/Airbus DS, USDA, USGS,

1:2,400

20
Media

SOURCE PATHWAY RECEPTOR

AOI 1 –

Hangar 1 

and Helipad 

Area

Possible 

AFFF release 

from 

discharge of 

fire 

extinguisher

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 Transport and Migration Media Exposure Routes

Inhalation of 

Dust

Ingestion

Ingestion

Ingestion

Ingestion

Human Receptors: 

Current/ Future

Flow-Chart Continues

Partial / Possible Flow

Incomplete Pathway

Potentially Complete Pathway

Complete Pathway

Site 

Worker

Construction 

Worker Resident

Site 

Worker

Construction 

Worker Resident

/ / / /

/ / /

LEGEND

/ / / /

/ / / /

/ / / /

Figure 6-2

Preliminary Conceptual Site Model

Cheyenne AASF, Las Vegas, NV

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

Trespasser

Trespasser

Notes:

1. The resident and recreational user

receptors refer to an off-site resident and

recreational user.

2. Dermal contact exposure pathway is 

incomplete for PFAS.

Flow-Chart Stops

/

21
PFAS Preliminary Assessment Report

Cheyenne Army Aviation Support Facility Las

Vegas, Nevada

22

7. Conclusions

This document presents a summary of information on known or suspected management of AFFF

at Cheyenne AASF. The PA findings are based on personnel interviews, environmental

investigations and reports, historical documents, and the visual site inspection. The PA findings

are based on the information presented in Appendix A, Appendix B, and Appendix C.

7.1 Findings

One AOI related to potential PFAS releases discussed in Section 2 and Section 3 was identified

at the Cheyenne AASF based on PA data (Figure 7-1) and is described in Table 7-1 below:

Table 7-1: Areas of Interest

Area of Interest Name Used by Potential Release Dates

AOI 1 Hangar 1 and

Helipad Area NVARNG Prior to 2003

Based on potential PFAS releases at the AOI, there is potential for exposure to PFAS

contamination in media at or near the facility. The preliminary CSM for Cheyenne AASF is shown

on Figure 6-2, which presents the potential receptors and media impacted.

An adjacent potential PFAS release area was identified within the vicinity of the NVARNG facility.

North Las Vegas Airport had a plane crash on the runway in 2013, though it is unknown whether

AFFF were used to respond to these situations.

The summary of findings is presented in Figure 7-1.

7.2 Uncertainties

A number of information sources were evaluated during this PA to determine the potential for

PFAS-containing materials to have been present, used, or released at the facility. Historically,

documentation of PFAS use was not required because PFAS were considered benign. Therefore,

records were not typically kept by the facility or available during the PA on the use of PFAS in

training, firefighting, other non-traditional activities, or on its disposition. There is no historically

documented use of PFAS containing materials at Cheyenne AASF by NVARNG staff.

The conclusions of this PA are based on all available information, including: previous

environmental reports, EDRsTM, observations made during the VSI, and interviews. Interviews of

personnel with direct knowledge of a facility generally provided the most useful insights regarding

a facility's historical and current PFAS-containing materials. Sometimes, the provided information

was vague. Gathered information has a degree of uncertainty due to the absence of written

documentation, the limited number of personnel with direct knowledge due to staffing changes,

the time passed since PFAS were first used, and a reliance on personal recollection. Inaccuracies

may arise in suspected AFFF discharge locations, discharge dates, discharge volumes, and PFAS

concentration. There is also a possibility the PA has missed a source of PFAS, as the science of

how PFAS may enter the environment continually evolves.

At Cheyenne AASF, uncertainty lies in whether or not AFFF releases occurred at Hangar 1 or

from a fire extinguisher discharged at the edge of the helipad area. In order to minimize the level

of uncertainty, readily available data regarding the use and storage of PFAS were reviewed,
PFAS Preliminary Assessment Report

Cheyenne Army Aviation Support Facility Las

Vegas, Nevada

23

current personnel were interviewed from NVARNG, multiple persons were interviewed for the

same potential source area, and potential source areas were visually inspected.

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

Table 7-2: Sources of Uncertainties

Area of Interest Source of Uncertainty

AOI 1 Hangar 1 and Helipad Area Records of AFFF use and releases were not

typically kept, and recollections may be

incomplete.

7.3 Potential Future Actions

Interviews with NVARNG facility staff whose first-hand knowledge at Cheyenne AASF span 2003-

present indicate that ARNG activities may have resulted in a potential PFAS release at the AOI

identified during the PA. Based on the preliminary CSM developed for the AOI, there is potential

for trespassers and site and construction workers to be exposed to PFAS contamination in surface

and subsurface soil via ingestion and inhalation of dust. Table 7-3 summarizes the rationale used

to determine if the AOI should be considered for further investigation under the CERCLA process

and undergo an SI.

Table 7-3: PA Findings Summary

Area of

Interest AOI Location Rationale PotentialFuture Action

AOI 1 Hangar 1

and Helipad

Area

36°12'59.07"N; 

115°12'07.53"W

Storage of Tri-MaxTM and AFFF fire

extinguisher; potential discharge of fire

extinguisher possibly containing AFFF

Proceed to an

SI, focus on soil

ARNG will evaluate the need for an SI at AOI 1 at the NVARNG Cheyenne AASF based on the

potential receptors, the potential migration of PFAS contamination off the facility, and the

availability of resources.
North Las

Vegas

Airport

0 700 1,400 2,800

Feet

Legend

Area of Interest

Potential PFAS Release

Facility Boundary

Wetland

River/Stream

CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

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12420 Milestone Center Drive

Germantown, MD 20876

Summary of Findings

Base Map: Source: Esri, DigitalGlobe, GeoEye,

Earthstar Geographics, CNES/Airbus DS, USDA, USGS,

1:16,800

Possible FTA

Trimax Storage 

Area Trimax Storage 

Area

AOI 1

0 75 150 300

Feet

24
PFAS Preliminary Assessment Report

Cheyenne Army Aviation Support Facility Las

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25

8. References

Bell, John W. 2016. Las Vegas Valley: Land Subsidence and Fissuring Due to Ground-Water

Withdrawal. United States Geological Survey (USGS). U.S. Department of the Interior.

https://geochange.er.usgs.gov/sw/impacts/hydrology/vegas_gw/ Accessed November

2019.

Broadbent & Associates, Inc. March 2019. Phase 1 Environmental Site Assessment Nevada

Army National Guard – Cheyenne Air Center Hangars 1&2. Nevada Army National

Guard. APN Number: 139-18-101-006. Project Number: 18-01-250-101.

Clark County Department of Aviation. 2016. North Las Vegas Airport Celebrates Its 75th

Anniversary. http://vgt.aero/Events/Anniversary Accessed November 2019.

Las Vegas Valley Groundwater Management Program (Las Vegas GMP). 2019. Wells &

Groundwater. Southern Nevada Water Authority.

https://lasvegasgmp.com/wells-groundwater/ Accessed November 2019.

Las Vegas Valley Water District (LVVWD). 2019. Where Your Water Comes From.

https://www.lvvwd.com/water-system/where-your-water-comes-from/index.html

Accessed November 2019.

National Oceanic and Atmospheric Administration. 2019. Climate Data Online Database.

https://www.ncdc.noaa.gov/cdo-web/datatools/normals

National Transportation Safety Board (NTSB). 2015. NTSB Identification: WPR13LA082.

https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20130102X03247&key=1

Skrbac, Paul H. 2005. NOAA Technical Memorandum NWS WR-271. Climate of Las Vegas,

Nevada. National Oceanic and Atmospheric Administration.

https://repository.library.noaa.gov/view/noaa/6543

US Environmental Protection Agency (USEPA), 1991. Guidance for Performing Preliminary

Assessments under CERCLA. EPA/540/G91/013.

Wyman, R.V. & Karakouzian, Moses & Bax-Valentine, V. & Peterson, L. & Palmer, S. &

Slemmons, D.B. (1993). Geology of Las Vegas, Nevada, United States of America.

Bulletin of the Association of Engineering Geologists; (United States). 30:1. 

10.2113/gseegeosci.xxx.1.33.

https://www.researchgate.net/publication/236474105_Geology_of_Las_Vegas_Nevada

_United_States_of_America
PFAS Preliminary Assessment Report

Cheyenne Army Aviation Support Facility Las

Vegas, Nevada

Appendix A

Data Resources
PFAS Preliminary Assessment Report

Cheyenne AASF, Las Vegas, Nevada

Data Resources will be provided separately on CD. Data Resources for Cheyenne AASF 

facility include:

Cheyenne AASF Previous Investigations

· 2019 Broadbent. Phase 1 Environmental Site Assessment. NVARNG Cheyenne Air Center

Hangars 1& 2

Cheyenne AASF Facility Information

· 2018 Cheyenne Hangar 1 Lease 5 yr

· 2018 Cheyenne Hangar 2 Lease 5 yr

Cheyenne AASF EDRTM Report

· 2019 Cheyenne AASF Environmental Data Resource Report
PFAS Preliminary Assessment Report

Cheyenne Army Aviation Support Facility Las

Vegas, Nevada

Appendix B

Preliminary Assessment Documentation
PFAS Preliminary Assessment Report

Cheyenne Army Aviation Support Facility Las

Vegas, Nevada

Appendix B.1

Interview Records


PFAS Preliminary Assessment Report

Cheyenne Army Aviation Support Facility Las

Vegas, Nevada

Appendix B.2

Visual Site Inspection Checklists

PFAS Preliminary Assessment Report

Cheyenne Army Aviation Support Facility Las

Vegas, Nevada

Appendix B.3

Conceptual Site Model Information



PFAS Preliminary Assessment Report

Cheyenne Army Aviation Support Facility Las

Vegas, Nevada

Appendix C

Photographic Log
Preliminary Assessment Report

Army Aviation Support Facility Reno

Perfluorooctane-Sulfonic Acid (PFOS) and 

Perfluorooctanoic Acid (PFOA) Impacted Sites

ARNG Installations, Nationwide

APPENDIX C – Photographic Log

Army National Guard, Preliminary 

Assessment for PFAS

Cheyenne Army Aviation Support 

Facility Las Vegas, Nevada

Photograph No. 1

Description:

Facing West. Former Trimex 

storage area

Photo Date: 09/20/2019 0914 

Photograph No. 2

Description:

Facing West. Former Trimex 

storage area

Photo Date: 09/20/2019 0915 
Preliminary Assessment Report

Army Aviation Support Facility Reno

Perfluorooctane-Sulfonic Acid (PFOS) and 

Perfluorooctanoic Acid (PFOA) Impacted Sites

ARNG Installations, Nationwide

APPENDIX C – Photographic Log

Army National Guard, Preliminary 

Assessment for PFAS

Cheyenne Army Aviation Support 

Facility Las Vegas, Nevada

Photograph No. 3

Description:

Facing East. Water sprinkler 

system.

Photo Date: 09/20/2019 0916 

Photograph No. 4

Description:

Facing North. New fire 

extinguisher which also 

contains AFFF.

Photo Date: 09/20/2019 0922 
Preliminary Assessment Report

Army Aviation Support Facility Reno

Perfluorooctane-Sulfonic Acid (PFOS) and 

Perfluorooctanoic Acid (PFOA) Impacted Sites

ARNG Installations, Nationwide

APPENDIX C – Photographic Log

Army National Guard, Preliminary

Assessment for PFAS Army Aviation Support Facility Reno Reno, Nevada

Photograph No. 5

Description:

Facing West. Area where FTA

possibly occurred. Polymer

coating applied in 2016

Photo Date: 09/20/2019 0919