FINAL

Preliminary Assessment Report

Buckley Army Aviation Support Facility, 

Aurora, Colorado

Perfluorooctanesulfonic Acid (PFOS) and Perfluorooctanoic Acid 

(PFOA) Impacted Sites

ARNG Installations, Nationwide

February 2021

Prepared for:

Army National Guard Bureau

111 S. George Mason Drive

Arlington, VA 22204

UNCLASSIFIED
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, Colorado

i

Table of Contents

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

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

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

1.5.2 Hydrogeology .................................................................................................7

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

1.5.4 Climate ...........................................................................................................8

1.5.5 Current and Future Land Use .........................................................................8

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

3. Non-Fire Training Areas ...................................................................................................13

4. Emergency Response Areas ............................................................................................18

5. Adjacent Sources .............................................................................................................19

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

7. Conclusions and Data Uncertainty ...................................................................................28

8. References ......................................................................................................................32
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, Colorado

ii

Figures

Figure ES-1 Summary of Findings

Figure ES-2 Preliminary Conceptual Site Model Buckley AASF, CO

Figure 1-1 Facility Location

Figure 1-2 Groundwater Features

Figure 1-3 Surface Water Features

Figure 3-1 Non-Fire Training Areas

Figure 5-1 Adjacent Sources

Figure 6-1 Areas of Interest

Figure 6-2 Preliminary Conceptual Site Model for AOI 1 Building 1510

Figure 6-3 Preliminary Conceptual Site Model for AOI 2 Former Tri-MaxTM Storage Area

Figure 7-1 Summary of Findings

Tables

Table ES-1 AOIs at Buckley AASF

Table 5-1 Buckley AFB AFFF Release Locations

Table 7-1 AOIs at Buckley AASF

Table 7-2 No Suspected Release Areas

Table 7-3 Sources of Uncertainty

Table 7-4 PA Findings Summary

Appendices

Appendix A Data Resources

Appendix B Preliminary Assessment Documentation

B.1 Interview Records

B.2 Conceptual Site Model Information
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, Colorado

iii

Acronyms and Abbreviations

°F degrees Fahrenheit

μg/kg micrograms per kilogram

μg/L micrograms per liter

AASF Army Aviation Support Facility

AECOM AECOM Technical Services, Inc.

AFB Air Force Base

AFFF aqueous film forming foam

ANG Air National Guard

AOI Area of Interest

ARNG Army National Guard

bgs below ground surface

CERCLA Comprehensive Environmental Response, Compensation, and Liability

Act

CFR Code of Federal Regulations

COANG Colorado Air National Guard

COARNG Colorado Army National Guard

CSM conceptual site model

EDRTM Environmental Data Resources, Inc.TM

FEMA Federal Emergency Management Agency

ft feet

FTA fire training area

GSE Ground Services Equipment

HA Health Advisory

HEF High Expansion Foam

IED

msl

Installations & Environment Division

mean sea level

NOAA National Oceanic and Atmospheric Administration

OWS Oil-water separator

PA Preliminary Assessment

PFAS per- and poly-fluoroalkyl substances

PFBS perfluorobutane sulfonate

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

ROD Record of Decision

SDS Safety Data Sheet

SI Site Inspection

US United States

USACE United States Army Corps of Engineers

USEPA United States Environmental Protection Agency

USFWS United States Fish and Wildlife Service

WWTP Wastewater treatment plant
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, Colorado

1

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 poly-fluoroalkyl substances

(PFAS)-containing materials was completed at Buckley Army Aviation Support Facility (Buckley

AASF; also referred to as the “facility”), in Aurora, Colorado. The performance 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 interviews with Colorado ARNG (COARNG) personnel, including current and

former Environmental Protection Specialists, the Environmental Compliance Manager, the

Facility Unit Environmental Compliance Officer, and the Facility Maintenance Supervisor;

· Identified Area(s) of Interest (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.

Two AOIs related to potential PFAS release were identified at Buckley AASF based on PA data

(Figure ES-1) and are summarized in Table ES-1 below:

Table ES-1: AOIs at Buckley AASF

Area of Interest Name Used by Potential Release Dates

AOI 1 Building 1510 COARNG 2006, 2019

AOI 2 Former Tri-MaxTM Storage Area COARNG Unknown - 2019

Based on the possible PFAS releases at AOI 2 and the uncertain content of High Expansion Foam

(HEF) at AOI 1, there is potential for exposure to PFAS contamination in surface soil to site and

construction workers, and trespassers via ingestion and inhalation; in subsurface soil to

construction workers via ingestion and inhalation; and in surface water to site construction

workers and off-facility recreational users via ingestion. There is also the potential for residents to

consume produce grown off-facility that has been exposed to PFAS via the agricultural use of

biosolids for fertilizer generated at the Robert W. Hite Treatment Facility and potentially containing

PFAS from impacted wastewater from the facility. Additionally, domestic and irrigation wells

downgradient of Buckley AASF create a potentially complete pathway for PFAS exposure to offfacility residents via ingestion of groundwater. Numerous adjacent sources were identified where

PFAS releases to the environment occurred outside of the COARNG property boundary. The

preliminary CSM for Buckley AASF, which presents the potential receptors and media impacted,

is shown on Figure ES-2.

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 water system

above the USEPA’s Lifetime Health Advisory level within 20 miles of the facility. 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.
East Toll Gate Creek

Highlin e Canal

W est Toll Gate Creek

SandCreek

Lake

Williams

Aurora Fire

Station No. 9

IRP Site 3 - Former

Base Landfill

Aurora Fire

Station No. 8

F-16 Crash

Location

Former Fire

Station No. 2

FTA No. 2

F-5 Crash

Location

FTA No. 3

Hangar 801

AOI 1

AOI 2

0 1,250 2,500 5,000

Feet

E ast Toll Gate Creek

Building 1520

Building 1515 Building 1500

Building 1000

Building 1511A Building 1004

Building 1005

Hangar 909

GSE Building

Area

Building 1510

Former Tri-Max

Storage Area

Stormwater Retention Pond

Surface Impoundment

AOI 1

AOI 2

­ Figure ES-1

CLIENT

REVISED

SCALE

PROJECT

ARNG

Preliminary Assessment for PFAS at Buckley AASF, CO

4/8/2020

4/8/2020

4/8/2020

MS

JW

RG

GIS BY

CHK BY

PM

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

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

4/8/2020

1:30,000

C:\Users\stankevichm\OneDrive - AECOM Directory\ARNG_PFAS_GIS_60552172\MXDs\CO\Buckley_AASF_Figures\Buckley_AASF_PA_Figures\Fig_ES-1_Buckley_AASF_Summary.mxd

Area of Interest

Potential PFAS Release

No Suspected Release

Facility Boundary

Water Body

River/Stream

Canal/Ditch

Pipeline

Summary of Findings

12420 Milestone Center Drive

Germantown, MD 20876

0 300 600 1,200

Feet

Aurora WWTP 

Approx 6 miles

2
Media

SOURCE PATHWAY RECEPTOR

AOI 1 – AOI 2

Potential HEF 

release from fire 

suppression 

system, and 

potential 

incidental AFFF 

releases as a 

result of Tri-Max 

storage

PFAS in 

Surface 

Soil / Paved 

Surfaces and 

Sanitary 

Sewers

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

Buckley AASF, CO

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

Tresspasser/

Recreational User

Tresspasser/

Recreational User

Notes:

1. The resident and recreational user

receptors refer to an off-site resident and

recreational user.

2. The site worker and construction worker 

receptors refer only to COARNG Buckley AASF 

site and construction workers.

3. Dermal contact exposure pathway is 

incomplete for PFAS.

Flow-Chart Stops

3
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, Colorado

4

1. Introduction

Authority and Purpose

The Army National Guard (ARNG)-Installations & Environment Division 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), 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 Drinking Water Lifetime Health 

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

national standards regulating PFAS in drinking water. In the absence of federal maximum 

contaminant levels, some states have adopted their own drinking water standards for PFAS. 

Colorado does not currently have drinking water standards for PFAS. Colorado House Bill 1279 

was passed in June 2019 and prohibits the sale of PFAS-containing firefighting foam in certain 

circumstances, prohibits the use of PFAS-containing foam for training, and requires the Colorado 

Department of Health to conduct a survey to determine the amount of PFAS-containing foam 

currently held, used, and disposed of by state fire departments (House Bill 19-1279, 2019 Regular 

Session [Co. 2019]). 

This report presents the findings of a PA for PFAS-containing materials at Buckley Army Aviation 

Support Facility (Buckley AASF; also referred to as the “facility”), in Aurora, Colorado, 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 locations where PFAS-containing materials may have been released into the 

environment at Buckley 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.

Preliminary Assessment Methods

The performance 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 interviews on 18 December 2019 with Colorado ARNG (COARNG) personnel, 

including current and former Environmental Protection Specialists, the Environmental 
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, Colorado

5

Compliance Manager, the Facility Unit Environmental Compliance Officer, and the Facility 

Maintenance Supervisor;

· Identified Area(s) of Interest (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;

· AECOM did not perform a site visit at Buckley AASF.

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 fire training areas (FTAs) at the facility 

identified during interviews 

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

at the facility identified during interviews 

· Section 4 – Emergency Response Areas: describes areas of potential PFAS release at the 

facility, specifically in response to emergency situations 

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

facility that are not under the control of ARNG 

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

and receptors for the AOIs and 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

Facility Location and Description

The Buckley AASF is a tenant of the Buckley Air Force Base (AFB) located in Aurora, Colorado 

(Figure 1-1). The COARNG has maintained a presence at Buckley AFB since 1977, when 

Building 1500 was constructed to be the facility hangar. Since 1977, the facility has been improved 

with numerous buildings and developments, with the most recent being the construction of 

Building 1510, a new facility main hangar. Buckley AASF is designed to house, equip, support, 

and maintain military aircrafts. The facility is located west of the Buckley AFB runway and includes 

hangar space for aircraft maintenance and storage, office and administrative buildings, a 

readiness center, a flight ramp, a helipad, and a taxiway connecting the facility flight ramp to the 

Buckley AFB runway. An additional joint-use building shared by the COARNG and Buckley AFB 

is located on a flight ramp predominantly used by Buckley AFB, approximately 0.5 miles north of 

the COARNG Buckley AASF complex. The larger Buckley AFB property, which is zoned entirely 

for Buckley AFB use, encompasses 3,540 acres. The COARNG Buckley AASF is leased from the 

Buckley AFB. The 2000 Department of the Army license for the use of the Buckley AASF property 

by the COARNG is included in Appendix A.
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, Colorado

6

The Department of the Army opened Buckley Field in 1942 to train the Army Air Corps, and they 

transferred the field to the Department of the Navy in 1945. The Navy deactivated the facility in 

1959, and operation of the facility transferred to the State of Colorado as Buckley Air National 

Guard (ANG) Base. Buckley ANG Base was used for military aviation and support activities for 

the Colorado ANG (COANG). The base was reassigned from the ANG to the Air Force Space 

Command and renamed Buckley AFB in 2001.

Facility Environmental Setting

Buckley AASF and the area surrounding the larger Buckley AFB complex includes industrial and 

agricultural land to the north, commercial and residential to the west, residential and agricultural 

to the south, and agricultural to the east (USEPA, 2019). Buckley AFB is situated on high ground 

dividing the Sand Creek and Toll Gate Creek drainage basins. The ground surface elevation of 

Buckley AFB ranges from 5,700 feet (ft) above mean sea level (msl) at the southeast corner to 

5,480 ft above msl at the northwest corner. The COARNG Buckley AASF is situated at 

approximately 5,585 ft above msl, towards the center of the AFB property (USEPA, 2019).

Most of the Buckley AASF facility is paved with asphalt or concrete, with the exception of grassy 

areas surrounding the improved portions of the facility. The facility is bounded on the north, west, 

and south sides by a chain-link fence; the eastern boundary of the property is open to the greater 

Buckley AFB area. According to facility personnel, Buckley AASF is provided drinking water by 

the City of Aurora, and sanitary sewers connect the facility to the Denver Metro Wastewater 

Reclamation District.

1.5.1 Geology

Buckley AASF is located within the Denver Basin, a shallow, bowl-shaped basin covering an area 

of approximately 6,700 square miles. The basin is filled with sedimentary rocks formed by 

deposition resulting from the uplift and erosion of the Rocky Mountains to the west.

These sedimentary deposits are comprised of six geologic formations, which follow in descending 

order: the Castle Rock Conglomerate, the Dawson Arkose, the Denver, Arapahoe, and Laramie 

formations, and the Fox Hills Sandstone. The Cretaceous Pierre Shale Formation, consisting 

primarily of relatively impermeable shale, is located beneath the Fox Hills Sandstone within the 

Denver Basin. Of the six geologic formations found in the Denver Basin, only the Denver, 

Arapahoe, and Laramie formations and the Fox Hills Sandstone are found under the larger 

Buckley AFB property (USEPA, 2019).

The majority of the Denver Formation is composed of approximately 70 percent shale and 

claystone, with the remaining materials composed of coarser-grained sediments irregularly 

dispersed in lenticular beds. Under Buckley AFB, the Denver Formation is approximately 850 ft 

thick and crops out in the northeastern, eastern, and southwestern parts of the base, including 

beneath much of the AASF (USEPA, 2014). Where the Denver Formation is not present at the 

surface, it is often covered with a thin mantle of aeolian (windblown) deposits of loess and fine 

sand that are generally less than 10 ft thick. Additionally, alluvial deposits from the erosion of the 

Denver Formation are present along the valleys of the Sand and Toll Gate creeks and their 

tributaries, as well as in buried paleochannels (USEPA, 2019). A 2019 Record of Decision (ROD) 

for a property within the Buckley AFB encountered alluvial, and possibly aeolian, soils from ground 

surface to approximately 12 ft below ground surface (bgs). Below the alluvium is predominately 

the weathered claystone and siltstone of the Denver Formation, with minor weathered, 

interbedded sandstone (USEPA, 2019). Local geologic units are shown on Figure 1-2.
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, Colorado

7

1.5.2 Hydrogeology

Groundwater under the greater Buckley AFB area exists within the unconsolidated aeolian and

alluvial surficial deposits, as well as in the Denver Formation, where it is primarily present in the

discontinuous layers of coarse-grained materials (sand and sandstones) within the fine-grained

materials (clay, silt, claystones, and siltstones). Groundwater in the Denver Formation may also

exist in fractured sections of siltstones and claystones. Generally, unconfined groundwater

conditions exist in the weathered, upper part of the Denver Formation and overlying surficial

deposits, whereas semiconfined or confined conditions are present in the deeper portions of the

Denver Formation, particularly where it is overlain by other bedrock formations. Aquifer recharge

across Buckley AFB occurs through direct infiltration of precipitation and/or irrigation and drainage

ditch water. Groundwater discharge occurs primarily through seepage at streams and as

evapotranspiration where groundwater is present at formation outcrops (USEPA, 2014).The

Denver, Arapahoe, and Laramie-Fox Hills Aquifers are the three principal bedrock aquifers at

Buckley AFB (in descending order). Due to the thickness and hydrogeologic conditions of the

Denver Formation, surficial PFAS releases are unlikely to impact the deeper aquifers. The Denver

Formation is 600 to 1,000-ft thick (Aerostar SES LLC, 2019).

Regional groundwater flow is generally to the northwest, following the trend of stream drainages

toward the South Platte River north of Denver (Figure 1-2) (URS, 2007). Groundwater flow

direction at a former landfill adjacent to the southwest of the facility is towards the northwest and

is presumed to be the same at the facility (USEPA, 2014).

The Denver Basin aquifer system, which includes the Denver, Arapahoe, and Laramie-Fox Hills

aquifers, is a secondary source of municipal or irrigation water for suburban Denver and

surrounding rural communities. Unconfined shallow groundwater within the unconfined aquifers

in and around Buckley AASF is used primarily for irrigation. The City of Aurora, which supplies

drinking water for Buckley AASF and surrounding residents, draws most of its water from surface

sources (USEPA, 2019).

The Denver Aquifer groundwater at Buckley AASF is not used as a water source for drinking or

irrigation for the COARNG or off-site receptors. According to the 2014 ROD for the previously

mentioned former landfill located approximately 0.2 miles south of Buckley AASF, depth to

groundwater is estimated to be between 40 and 50 ft bgs in the southeastern portion of the landfill.

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. Numerous wells of various use exist in all directions surrounding

the facility.

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

PFAS were detected in a public water system above the HA within 20 miles of Buckley AASF.

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.

1.5.3 Hydrology

Surface water flow across most of the facility follows topography and drains via overland sheet

flow to the north, to a stormwater retention pond located north of Building 1510 on the northern

boundary of the COARNG property. The southern portion of the facility flight ramp drains to a

surface impoundment located east of Building 1515. Three storm drains located across the flight

ramp connect to underground storm sewer pipes that presumably discharge to the

aforementioned stormwater retention pond. A fourth storm drain on the flight ramp located

adjacent to the aircraft wash rack connects to sanitary sewer pipes that continue off-facility. A
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, Colorado

8

drainage swale on the northeast boundary of the flight ramp flows north towards the stormwater

retention pond, and a drainage swale adjacent to the southern boundary of the flight ramp drains

southwest towards the surface impoundment east of Building 1515. An oil-water separator (OWS)

is located east of Building 1510, at the adjacent parking pad, as well as at the southwest corner

of the building on the flight ramp (COARNG, 2017).

A small stream designated as a freshwater emergent wetland by the US Fish and Wildlife Service

(USFWS) National Wetlands Inventory passes through the eastern and northern portions of the

facility, and it ultimately discharges to the East Toll Gate Creek west of the facility (USFWS, 2020).

The East Toll Gate Creek is located approximately 0.2 miles west of the western AASF boundary

and flows to the northwest. East Toll Gate Creek confluences with Sand Creek approximately 5.5

miles northwest of the facility, and it ultimately discharges to the South Platte River further

northwest. Lake Williams, a freshwater pond, is also located within the greater Buckley AFB,

approximately 1 mile northeast of the AASF property (USFWS, 2020). Overflow from Lake

Williams drains through a series of two unnamed tributaries to Sand Creek (USEPA, 2019).

Nearby surface water bodies are shown on Figure 1-3.

Flood Insurance Rate Maps for Arapahoe County identify the entire Buckley AFB as an area of

minimal flood hazard. The nearest flood zone is associated with the East Toll Gate Creek

floodplain and is located approximately 0.2 miles northwest of the facility (Federal Emergency

Management Agency [FEMA], 2020).

1.5.4 Climate

Data from the Denver International Airport weather station, located approximately 11 miles

northeast of the COARNG AASF, indicate that the annual average temperature between 1981

and 2010 was 50.5 degrees Fahrenheit (oF) (National Oceanic and Atmospheric Administration

[NOAA], 2020). The warmest months are July and August, with normal daily average

temperatures of 74.2oF and 72.5oF, respectively. December is the coldest month, with an average

temperature of 30.0oF. Average annual precipitation measured from 1981 to 2010 at the airport

was 14.30 inches, with the most rain occurring May through July (NOAA, 2020). The average

annual snowfall for the nearby City of Denver, as reported by the Western Regional Climate

Center, is 53.8 inches (Western Regional Climate Center, 2020). The majority of snowfall occurs

between February and April.

1.5.5 Current and Future Land Use

The Buckley AASF is designed to house, equip, support, and maintain military helicopters for the

COARNG. Future land use at the AASF is not anticipated to change, given its recent construction.

The land use of the surrounding Buckley AFB is also not anticipated to change.
CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

JW

1/29/2020

1/29/2020

NOTES Preliminary Assessment for PFAS at Buckley AASF, CO

1:63,360

1/29/2020 ­ Figure 1-1 PM RG 1/29/2020

12420 Milestone Center Drive

Germantown, MD 20876

Facility Location

Base Map: Sources: Esri, HERE, Garmin, USGS,

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

Legend

Facility Boundary

^_

0 0.5 1 2

Miles

Buckley AASF

9
A!

!P

A! AA!!

A!

!P

A!

!P

!P

A!

!5 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!

A!

A!

A!

A!

A!

A!

A!

A!!

A!A! A!A! A!A!

A! A! A!

A!

A!

A!

A!

A!

A!

A!

A!

A!

A!

A!A!

A!

A!

A!A!A!

A! A! A!

A!

A!A!

A!

A!

A!

A!

A!

!P

!P !P

!P

!P

!P

!5

!P

!P

!P

!P

!P

!P

!P

A!PA!

!P

A!

A!

A!

A! A!

!P 

!P

!P

A!

!P

!P

A!

A!

!P

!P!P

!P

!P

A!

A!

A!A!

AAA!!!

!P

A!

!P

!P

!P

!P

A!

!P

A!A!A!

A!

!P

!P

A!

A!

A!

A!

A!

A!

A!

A!

A!

A!

A!

!C(

A!

A!

A!A!

A!

A!A!

A!

A!

A!

A!

A!

!P

A!

!P!P

A!AA!!

A!!

A!

AA!!A!!

!P

A!

!P !P

!P

!P

!P !P

!P

!P

!P

!C(!C(

!P

A!

!5

!P

!P

!P

!5

!P

!5

!5

!5

!5

!5

!P

!P

!P

!P

!P !P

!P

!P

!P

!P

A!

!P !P

!P

!P

!P

!P

!P

!P

!P

!P

!P

!P

!P

!P

!P

!P

!P

!P

!P

!P

!P

!P

!P

!P

!P

!P

A!

!P

!P

!P

!P

!P

!P

!P

A!

A!

A!

!P

A!

A!

A!

East Toll Gate Creek

Coal Creek

Murphy Creek

Sand Creek

Lake

Williams

CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

JW

4/8/2020

4/8/2020

NOTES Preliminary Assessment for PFAS at Buckley AASF, CO

1:31,680

4/8/2020 ­ Figure 1-2 PM RG 4/8/2020

12420 Milestone Center Drive

Germantown, MD 20876

Groundwater Features

Base Map: Source: Esri, DigitalGlobe, GeoEye,

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

Legend

Facility Boundary

Water Body

River/Stream

Canal/Ditch

Pipeline

Inferred Groundwater Flow

Direction

Geology

Younger Quaternary

Alluvium

Quaternary Gravels and

Alluviums

Quaternary Eolian and

Dune Deposits

Lower Tertiary and

Cretaceous Denver

Formation

Wells

!P Domestic

!P Commercial

!5 Industrial

!5 Irrigation

A! Monitoring/Sampling

!C( Municipal

A! Other/Unknown

0 0.25 0.5 1

Miles

10
East Toll Gate Creek

Coal Creek

Murphy Creek

Sand Creek

Coal Creek

Watershed

Toll Gate

Creek

Watershed

Sand Creek

Watershed

Lake

Williams

Stormwater Retention Pond

Surface Impoundment

CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

JW

4/14/2020

4/14/2020

NOTES Preliminary Assessment for PFAS at Buckley AASF, CO

1:31,680

4/14/2020 ­ Figure 1-3 PM RG 4/14/2020

12420 Milestone Center Drive

Germantown, MD 20876

Surface Water Features

Base Map: Source: Esri, DigitalGlobe, GeoEye,

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

Legend

Facility Boundary

Water Body

River/Stream

Canal/Ditch

Pipeline

Surface Water Flow Direction

0 0.25 0.5 1

Miles

11
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, Colorado

12

2. Fire Training Areas

FTAs are considered areas where deliberate discharge of AFFF or other firefighting materials is

performed for purposes of training personnel. No FTAs were identified at Buckley AASF during

the PA through interviews and review of the Environmental Data Resources, Inc. (EDR)TM report

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. Buckley

AFB has its own fire department that responds to emergencies across the greater AFB area,

including the Buckley AASF. FTAs associated with the Buckley AFB fire department are located

on Buckley AFB, outside of the COARNG property and are discussed as adjacent sources in

Section 5.
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, Colorado

13

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. Several non-FTAs where 

AFFF could have been potentially stored and/or released were identified via interviews during the 

PA. A description of each non-FTA is presented below, and the non-FTAs are shown on Figure 3-

1. COARNG personnel interviewed for this PA have first-hand knowledge as employees stationed 

at Buckley AFB in various capacities (both as COARNG and COANG employees) spanning 1995 

to 2000 and 2016 to present. The collective tenure of COARNG employees that were interviewed 

as a part of this PA but stationed at other COARNG locations had knowledge of the Buckley AASF 

spanning from 1995 to present.

Building 1510

Building 1510 is the main hangar at Buckley AASF and is located on the north side of the facility 

flight ramp. The building was constructed in 2006 and is designed for the maintenance and 

storage of aircraft. Building 1510 includes ten bay doors with access to ten hangars as well as 

office and administrative space on the west end of the building. The eastern portion of the building 

was described during interviews with facility staff as the Ground Services Equipment (GSE) 

building.

Building 1510 is constructed with a High Expansion Foam (HEF) deluge fire suppression system 

that contains 900 gallons of Ansul Jet-X 2 3⁄4% HEF concentrate. A 55-gallon drum containing the 

same HEF concentrate product is also stored within Building 1510. According to facility personnel, 

the HEF deluge fire suppression system was tested in 2006, following its installation. The test 

involved the three-minute discharge of an unknown volume of Ansul Jet-X 2 3⁄4% HEF to the 

hangar area. HEF released during the test was confined to the building interior by the building 

walls and plastic sheeting in front of bay doors. Standing foam was drained via building floor 

drains that connect to sanitary system sewers and ultimately lead to the Denver Metro Wastewater 

Reclamation District system. Typically, floor drains in Building 1510 connect to an OWS, but a 

diverter was used to ensure HEF bypassed the OWS and flowed to sanitary sewers. According 

to facility staff with knowledge of the test, no HEF is known to have escaped the building during 

the test. No other fire suppression system tests involving the release of HEF have occurred at 

Building 1510 since its construction, and facility personnel stated that the HEF system room 

exhibits no evidence of corrosion, leakage, or spills. A video of the 2006 HEF system test provided 

by COARNG is included in Appendix A.

The Safety Data Sheet (SDS) for the Ansul product used in the Building 1510 fire suppression 

system does not include PFAS in its composition, but it only lists hazardous components. The 

Data Sheet for the product (Appendix A) states that Building 1510’s fire suppression system uses 

a hydrocarbon surfactant; however, no material information definitively states that Ansul Jet-X 2 

3⁄4% HEF Concentrate does not include PFAS.

Additionally, Buckley AASF formerly stored six Tri-MaxTM wheeled fire extinguishers containing 

Chemguard 3% C-303 AFFF concentrate in the northeast corner of the COARNG property, east 

of Building 1510. In September 2019, a capture berm was assembled in the GSE Building portion 

of Building 1510 for the transferal of the AFFF concentrate contents of the Tri-MaxTM units into 

storage drums. Facility personnel present during the operation stated that no spills occurred, and 

three drums of AFFF concentrate were generated from the Tri-MaxTM units. The drums were 

disposed of by Buckley AFB along with other AFB waste materials. Waste manifest documents 
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, Colorado

14

for the disposal of the drums are included in Appendix A. The empty Tri-MaxTM units were moved 

to Building 1511A for storage.

Based on the known release of HEF during the 2006 fire suppression system test and the 

uncertainty of PFAS content in HEF, Building 1510 is considered a potential PFAS release area.

Former Tri-MaxTM Storage Area

As previously stated, Buckley AASF formerly stored six Tri-MaxTM wheeled fire extinguishers 

containing Chemguard 3% C-303 AFFF concentrate in the northeast corner of the COARNG 

property. It is unclear how long the Tri-MaxTM units were stored in this location, but they were 

removed and disposed of in a controlled manner in September 2019. Facility personnel present 

during the disposal stated that no spills occurred. Based on the outdoor storage of the Tri-MaxTM

units and the corrosive nature of AFFF, it is possible that incidental releases occurred in this area.

Based on the potential for incidental release of AFFF from Tri-MaxTM units during their outdoor 

storage, the Former Tri-MaxTM Storage Area is considered a potential PFAS release area.

Building 1511A

Building 1511A is a cold storage building at Buckley AASF and is located on the west end of the 

flight ramp. The building was constructed circa 2006, at the same time Building 1510 was 

constructed. According to facility personnel, Building 1511A is not equipped with a fire suppression 

system and has never been the location of an emergency requiring AFFF use in response. Empty 

Tri-MaxTM units that formerly stored Chemguard 3% C-303 AFFF concentrate have been stored 

within Building 1511A since September 2019, after their contents were transferred to drums for 

disposal off-facility. The empty Tri-MaxTM units are designated to be rinsed prior to disposal offfacility by a private contractor; however, the units had not been disposed of at the time of this PA. 

It is presumed that floor drains in Building 1511A connect to sanitary system sewers similarly to 

the floor drains in Building 1510.

Personnel whose tenure with the COARNG span the entire history of the AASF stated during 

interviews that no known AFFF releases have occurred at Building 1511A. Building 1511A is not 

considered a potential PFAS release area.

Building 1500

Building 1500 is located towards the southwest corner of the flight ramp, and consists of two 

aircraft hangars and an attached office space. It is used for the maintenance and storage of 

military aircraft. According to COARNG interviewees, Building 1500 was constructed in 1977 and 

has been used as a hangar by the COARNG since its construction. 

According to COARNG interviewees, the fire suppression system at Building 1500 uses only 

water, and no emergency events requiring AFFF use have ever occurred at the building. In 

December 2017, a marine helicopter leaked approximately 0.5 gallons of oil on the paved area 

east of Building 1500. Personnel present during the spill stated that sorbent pads were used to 

clean the oil, and Halon was present as a cautionary measure in response to the spill. The specific 

type of Halon product present and the capacity in which it was used are unknown. Halon is a fire 

extinguishing agent that contains bromochlorodifluoromethane and is almost universally used as 

an aircraft fire extinguisher. As a chlorofluorocarbon, Halon production has ceased, but many 

Halon products remain in circulation until used for their intended purpose. An incident report form 

for the oil spill is included in Appendix A. No evidence indicates that AFFF has ever been used 
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, Colorado

15

or stored at Building 1500, and no other known emergencies have occurred at the building. 

Building 1500 is not considered a potential PFAS release area.

Building 1515

Building 1515 is another hangar at the AASF used for the maintenance and storage of military 

aircraft in the southwest corner of the flight ramp. Based on historical aerial imagery, Building 

1515 was constructed in 2014 and was previously used as a storage area, with two smaller 

buildings occupying the space. The materials stored in this area prior to the construction of 

Building 1515 and the purpose of the previous buildings occupying the space are unknown.

According to COARNG interviewees, there is no fire suppression system at Building 1515, and 

no emergency events requiring AFFF use have ever occurred at the building. No evidence 

indicates that AFFF has ever been used or stored at Building 1515; Building 1515 is not 

considered a potential PFAS release area. 

Building 1000

Building 1000 operates as a readiness center at Buckley AASF and is located west of Building 

1511A, in the western portion of COARNG property. Based on historical aerial imagery, Building 

1000 was constructed between 1984 and 1991, and an addition on the southern side of the 

building was constructed in 2004. According to COARNG interviewees, the building has operated 

as a readiness center for the COARNG since its construction.

No evidence indicates that AFFF has ever been stored or used at the readiness center, and the 

building does not include an AFFF fire suppression system. No emergency events requiring AFFF 

use are known to have ever occurred at the building. Building 1000 is not considered a potential 

PFAS release area. 

Building 1005

Building 1005 is used as an administrative and office space for active guard duty operations, and 

it is the northwestern-most building associated with the Buckley AASF. Based on historical aerial 

imagery, Building 1005 was constructed between 1993 and 1994. According to COARNG 

interviewees, Building 1005 has always operated as a readiness center/administrative office 

space.

No evidence indicates that AFFF has ever been stored or used at Building 1005, and no 

emergency events requiring AFFF use are known to have ever occurred at the building. Building 

1005 is not considered a potential PFAS release area. 

Hangar 909

Hangar 909 is a joint-use building shared by the COARNG and Buckley AFB. The hangar is 

located on a flight ramp predominantly used by Buckley AFB, approximately 0.5 miles north of the 

COARNG Buckley AASF complex. Information provided in a 2015 PA for perfluorinated 

compounds at Buckley AFB indicates that Hangar 909 has never been equipped with fire 

suppression systems, and the hangar was not further investigated for PFAS (HydroGeoLogic, 

Inc., 2015). COARNG interviewees confirmed the findings of the PA with respect to Hangar 909 

and do not consider the area to be of PFAS concern.

No evidence indicates that AFFF has ever been stored or used at Hangar 909; it is not considered 

a potential PFAS release area. 
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, Colorado

16

Flight Ramp

The Flight Ramp is located at the center of the Buckley AASF property and comprises 

approximately 12 acres of paved surface used for aircraft parking. Based on historical aerial 

imagery, the Flight Ramp was constructed between 1970 and 1979. Based on the COARNG 

presence at Buckley AASF since 1977, the Flight Ramp is presumed to have been operated by 

the COARNG for the entirety of its existence. Flight ramps may commonly be the location for 

incidents involving fueling or maintenance that may require fire suppression or prevention; 

however, facility personnel stated that no incidents have occurred on the flight ramp requiring 

such response. The Flight Ramp is not considered a potential PFAS release area.
E ast Toll Gate Creek

Building 1520

Building 1515 Building 1500

Building 1000

Building 1511A Building 1004

Building 1005

Hangar 909

Stormwater Retention Pond

Surface Impoundment

GSE

Building

Area

Building 1510

Former

Tri-Max

Storage Area

CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

JW

4/8/2020

4/8/2020

NOTES Preliminary Assessment for PFAS at Buckley AASF, CO

1:7,200

4/8/2020 ­ Figure 3-1 PM RG 4/8/2020

12420 Milestone Center Drive

Germantown, MD 20876

Non-Fire Training Areas

Base Map: Source: Esri, DigitalGlobe, GeoEye,

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

Legend

Potential PFAS Release

No Suspected Release

Facility Boundary

River/Stream

0 300 600 1,200

Feet

17
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, Colorado

18

4. Emergency Response Areas

COARNG staff confirmed that no known incidents requiring AFFF fire suppression have occurred

during their collective tenure spanning from 1995 to 2000 and 2016 to present as employees

working at the facility, and from 1995 to present as COARNG employees with knowledge of the

facility. Emergency responses to crashes sometimes require flame suppression, which may result

in the release of PFAS to the environment in the form of AFFF.
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, Colorado

19

5. Adjacent Sources

Several potential off-facility sources of PFAS adjacent to the Buckley AASF, not under the control 

of the COARNG, were identified during the PA through interviews, review of the EDRTM report for 

a 1-mile radius surrounding the facility (Appendix A), and historical document review. Using 

additional online resources, such as state and local GIS databases, wells were researched to a 

4-mile radius of the facility. A description of each potential adjacent source is presented below, 

and the sources are shown on Figure 5-1.

Buckley Air Force Base

Fire training and other activities resulting in PFAS releases have occurred in several locations 

associated with the Buckley AFB. Based on a 2019 SI report for AFFF use at Buckley AFB 

(Appendix A), two FTAs, one hangar, the former fire station, and two crash sites were identified 

as areas where AFFF may have been released to the environment (Aerostar SES LLC, 2019). 

The 2019 SI report used the USEPA’s Regional Screening Level calculator to identify a screening 

level for PFOS and PFOA in soil and sediment of 126 micrograms per kilogram (μg/kg). Screening 

levels used for PFOS and PFOA in groundwater and surface water were based on the USEPA 

HA (0.07 micrograms per liter [μg/L]). The SI report also established a screening level of 130,000 

μg/kg for perfluorobutane sulfonate (PFBS) in soil and sediment, and 40 μg/L for PFBS in 

groundwater and surface water (Aerostar SES LLC, 2019).

The AFFF release areas at Buckley AFB investigated as part of the 2019 SI report are identified 

in Table 5-1 below. 

Table 5-1: Buckley AFB AFFF Release Locations

AFFF Release 

Areas Nature of Release or Potential Release

FTA No. 2 FTA No. 2 was an unlined burn area for jet fuels and was operational 

between 1950 and 1972. 2019 SI sample results indicated that PFOA and 

PFOS concentrations exceeded their respective screening criteria in 

surface soil and groundwater, and that a pathway for exposure to impacted 

drinking water is potentially complete.

FTA No. 3 Fire training exercises were performed annually at FTA No. 3 between 1972 

and 1989. Jet fuel solutions were ignited and extinguished with AFFF during 

training events; approximately 400 gallons of AFFF were used annually. In 

2006, a removal action was performed to remove soil impacted by volatile 

organic compounds, and in 2008, the area was paved over to become a 

parking lot.

2019 SI sample results indicated that PFOS concentrations exceeded 

screening criterion in surface soil, and PFOA and PFOS concentrations 

exceeded screening criteria in groundwater. The pathway for exposure to 

impacted drinking water is potentially complete.

Hangar 801 One documented release of approximately 400 gallons of Ansulite 3% 

AFFF mixed with 13,000 to 14,000 gallons of water is known to have 

occurred at Hangar 801. Approximately 2,000 to 5,000 gallons of the AFFF 

solution were released to sanitary sewers and migrated to the surface of a 
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, Colorado

20

AFFF Release 

Areas Nature of Release or Potential Release

nearby road. AFFF solution also migrated from the nearby road surface to 

stormwater sewers.

2019 SI sample results indicated that PFOA and PFOS concentrations 

exceeded screening criteria in groundwater, and the pathway for exposure 

to impacted drinking water is potentially complete.

Former Fire 

Station #2

AFFF was stored at the former fire station, and annual spray testing was 

conducted on an outdoor pad adjacent to the fire station, which resulted in 

the release of AFFF.

2019 SI sample results indicated that PFOS concentrations exceeded 

screening criterion in surface soil, and PFOA and PFOS concentrations 

exceeded screening criteria in groundwater. The pathway for exposure to 

impacted drinking water is potentially complete.

F-5 Crash Site Approximately 100 to 200 gallons of AFFF were sprayed on a fuel spill 

resulting from an aircraft crash on the Buckley AFB runway in the late 

1980s. 2019 SI sample results indicated that PFOS concentrations 

exceeded screening criteria in surface soil, and that a pathway for exposure 

to impacted drinking water is potentially complete.

F-16 Crash Site Approximately 200 gallons of AFFF were sprayed at the location of an 

aircraft crash on grass adjacent to the south end of the Buckley AFB runway 

in 1995. 2019 SI sample results indicated that no PFAS compounds were 

detected over their respective screening criteria, and that the pathway for 

exposure to impacted drinking water is considered incomplete.

City of Aurora Fire Stations 

Numerous fire stations associated with the City of Aurora Fire Department are located throughout 

the City of Aurora. Aurora Fire Station No. 9 and Aurora Fire Station No. 8 are the two nearest fire 

stations to the Buckley AASF that are associated with the City of Aurora Fire Department. Fire 

Station No. 9 is located approximately 1.8 miles southwest of the facility, and Fire Station No. 8 is 

approximately 2.5 miles northwest of the facility.

It is unknown whether the Aurora Fire Department fire stations store or use AFFF during training 

or emergency response. Given the tendency for local fire departments to store AFFF for 

emergency purposes, it is possible AFFF is stored at these locations. It is also unclear whether 

the fire department performs vehicle maintenance, such as nozzle tests, at the fire stations. Due 

to the likelihood that AFFF has been stored and/or released at the fire stations as a result of 

potential training and maintenance, the City of Aurora Fire Department fire stations are considered 

a potential PFAS release areas. 

Site 3 – Former Base Landfill

There are no landfills within the footprint of the COARNG property; however, Buckley AFB 

Installation Restoration Program Site 3 comprises the Former Base Landfill and is located 

immediately south of the Buckley AASF. Site 3 is a series of former disposal areas that were used 

between 1942 and 1982 for municipal refuse disposal. The general method of operation for the 
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, Colorado

21

Former Base Landfill was to dig a trench, fill the trench with waste material, and cover the material 

with earth. Portions of Site 3 are bisected by East Toll Gate Creek (USEPA, 2014). 

Landfills are not usually a primary potential release area of PFAS, but materials disposed of in 

landfills may create a secondary source of contamination. Such materials, to name a few, may 

include sludge from a wastewater treatment plant (WWTP) that processes PFAS-laden water, 

used AFFF storage containers, or products associated with waterproofing uniforms or boots. 

Known PFAS releases at locations on Buckley AFB may have contributed to waste-containing 

PFAS being disposed of at the landfill. As such, Site 3 is considered an adjacent potential PFAS 

release area.

WWTPs

There are no WWTPs located at the Buckley AASF. The Aurora WWTP is the nearest WWTP, and 

it is located approximately 6.3 miles northwest of the facility, along the Sand Creek. COARNG 

personnel stated during interviews that sanitary system sewers at the facility connect to the 

Denver Metro Wastewater Reclamation District. The Denver Metropolitan Wastewater 

Reclamation District includes the Robert W. Hite Treatment Facility, located approximately 12.5 

miles northwest of the facility, and serves an estimated 2 million people via 60 local governments 

and special districts, including Aurora. Treated sludge from the Denver Metropolitan Wastewater 

Reclamation District facilities is used as fertilizer at the Metrogro Farm, located approximately 65 

miles east of the City of Denver. Winter wheat, sorghum/sudan grass, and corn are grown at the 

Metrogro Farm, and pasture areas are often used for sheep and cattle grazing (Metro Wastewater 

Reclamation District, 2020).

WWTPs are not usually a primary potential release area of PFAS, but sludges and liquids from 

areas of potential release that are treated at WWTPs may create a secondary source of 

contamination. No known PFAS releases have occurred at the Buckley AASF, but adjacent AFFF 

releases could have resulted in the migration of PFAS in water to the Aurora WWTP, the Robert 

W. Hite Treatment Facility, and the Metrogro Farm. Agricultural products grown at the Metrogro 

Farm may create a potential pathway for human consumption of PFAS and expose grazing 

animals to PFAS. Due to the known adjacent AFFF releases surrounding the Buckley AASF, the 

Aurora WWTP, the Robert W. Hite Treatment Facility, and the Metrogro Farm are considered 

potential PFAS release areas. These locations are not shown on Figure 5 due to their distance 

from the Buckley AASF.
Highline Canal

West Toll Gate

Creek

East Toll Gate Creek

Lake Williams

Aurora Fire

Station No. 9

IRP Site 3 - Former

Base Landfill

Aurora Fire

Station No. 8

F-16 Crash

Location

Former Fire

Station No. 2

FTA No. 2

F-5 Crash

Location

FTA No. 3

Hangar 801

Legend

Potential PFAS Release

Facility Boundary

Water Body

River/Stream

Canal/Ditch

Pipeline

0 1,100 2,200 4,400

Feet

Adjacent Sources

Figure 5-1

CLIENT

REVISED

SCALE

2/25/2020 MS

JW

2/25/2020

2/25/2020

ARNG

GIS BY

CHK BY

TITLE

PROJECT Preliminary Assessment for PFAS at Buckley AASF, CO

Q:\Projects\ENV\GEARS\GEO\ARNG PFAS\900-CAD-GIS\920-GIS or Graphics\MXD\CO\Buckley_AASF_Figures\Buckley_AASF_PA_Figures\Fig_5-1_Buckley_AASF_Adjacent_Sources.mxd

PM RG 2/25/2020

1:26,400 ­ 12420 Milestone Center Drive

Germantown, MD 20876

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

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

22
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, Colorado

23

6. Preliminary Conceptual Site Model

Based on the PA findings, two AOIs were identified at Buckley AASF, AOI 1 Building 1510 and 

AOI 2 the Former Tri-MaxTM Storage Area. The AOI locations are shown on Figure 6-1. The 

following sections describe the CSM components and the specific preliminary CSM developed for 

each AOI. The CSMs identify the three components necessary for a potentially complete exposure 

pathway: (1) source, (2) pathway, (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 an insignificant 

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

continue to be the subject of PFAS toxicological study (National Ground Water Association, 2018). 

Receptors at the Buckley AASF include site workers, construction workers, trespassers, and offfacility recreational users of the surrounding water bodies. The preliminary CSM diagram for the 

Buckley AASF indicates which specific receptors could potentially be exposed to PFAS. 

 AOI 1 Building 1510

AOI 1 comprises Building 1510, the main hangar space at Buckley AASF, where potential PFAS 

releases may have occurred. PFAS releases are suspected to have occurred during the HEF fire 

suppression system test circa 2006. Although the HEF system test was described as being 

confined to the building interior, it is possible that HEF was tracked out of the building following 

the system test or during cleanup activities. 

Although it is unclear whether the HEF product released at Buckley AASF contains PFAS, it is 

conservatively assumed to do so for the purpose of this PA. If HEF released from the deluge 

system test were tracked outside of the building following the test, it may have migrated to the 

surrounding paved surfaces. Surface water runoff during storm events may have also carried 

PFAS to the landscaped areas on the north side of Building 1510. As such, it is possible that PFAS 

infiltrated subsurface soil via cracks in pavement, joints between areas that are paved with 

different materials on the north and south side of the building, and surface soil in the landscaped 

areas to the north. If HEF released at the AOI infiltrated surface soil, then surface soil presents a 

potentially complete pathway for PFAS exposure to site workers, construction workers, and 

trespassers via ingestion and inhalation. If HEF infiltrated subsurface soil at the AOI, then grounddisturbing activities may result in PFAS exposure to construction workers via ingestion and 

inhalation. Accidental ingestion of groundwater during ground-disturbing activities is not 

considered a potentially complete pathway for exposure to PFAS due to the presumed 40-50 ft 

depth to groundwater.

During the HEF system release, HEF was directed towards sanitary sewer drains that connect to 

Denver Metropolitan Wastewater Reclamation District facilities. These treatment facilities 

discharge to the South Platte River and transfer biosolids to the Metrogro Farm. The Metrogro 

Farm is used to grow agricultural products and for cattle grazing. As such, off-facility recreational 

users of the South Platte River as well as human and animal consumers of Metrogro Farm 

products may be exposed to PFAS via ingestion.

Surface water runoff may have also carried PFAS on paved surfaces around Building 1510 

towards the retention pond north of Building 1510. If any PFAS escaped the facility via surface 

water runoff and entered the small stream in the northeastern portion of the facility, it is also 

possible that PFAS may have migrated to East Toll Gate Creek, Sand Creek, and ultimately, the 

South Platte River. As such, surface water is considered a potentially complete pathway for off-
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, Colorado

24

facility recreational users of the surface water bodies and for Buckley AASF site 

workers/construction workers entering the retention pond north of Building 1510. 

PFAS are water soluble and can migrate readily from soil to groundwater via leaching. According 

to COARNG personnel, Buckley AASF and the surrounding areas are provided municipal water 

by the City of Aurora. Numerous wells of various types exist within the vicinity of the Buckley 

AASF, however, including domestic and irrigation wells downgradient of the facility (Appendix A). 

No drinking water wells exist at the facility. Because of the presence of domestic and irrigation 

wells downgradient from the AASF, groundwater is considered a potentially complete pathway for 

PFAS exposure to off-facility residents via ingestion. 

The preliminary CSM diagram for AOI 1 is shown in Figure 6-2.

AOI 2 Former Tri-MaxTM Storage Area

AOI 2 encompasses the area in the northeastern portion of the facility formerly used to store six 

Tri-MaxTM wheeled fire extinguishers containing Chemguard 3% C-303 AFFF concentrate. 

Although no known PFAS releases have occurred in this area, the outdoor storage of Tri-MaxTM 

and corrosive nature of AFFF may have led to incidental environmental releases of PFAS.

Potential PFAS releases at AOI 2 would most likely have occurred to paved surfaces, but may 

migrate a short distance to grassy areas. As such, it is possible that PFAS infiltrated surface and 

subsurface soil adjacent to the Former Tri-MaxTM Storage area as well as subsurface soil beneath 

the storage area via cracks in pavement and joints between areas that are paved with different 

materials. Surface soil presents a potentially complete pathway for PFAS exposure to site 

workers, construction workers, and trespassers via ingestion and inhalation. Ground-disturbing 

activities at the AOI may also result in PFAS exposure to construction workers via ingestion and 

inhalation of subsurface soil. Accidental ingestion of groundwater during ground-disturbing 

activities is not considered a potentially complete pathway due to depth to groundwater.

Surface water runoff from AOI 2 carrying PFAS may potentially migrate towards the retention pond 

north of Building 1510. It is also possible that surface water runoff from the area may enter the 

small stream in the northeastern portion of the facility. If such migration occurred, then PFAS may 

have migrated to East Toll Gate Creek, Sand Creek, and ultimately, the South Platte River. As 

such, surface water is considered a potentially complete pathway for off-facility recreational users 

of the surface water bodies and for Buckley AASF site workers/construction workers entering the 

retention pond north of Building 1510. 

As previously stated, Buckley AASF and the surrounding areas are provided municipal water by 

the City of Aurora; however, domestic and irrigation wells exist downgradient of the facility 

(Appendix A). Because of the presence of these domestic and irrigation wells, groundwater is 

considered a potentially complete pathway for PFAS exposure to off-facility residents via 

ingestion. 

The preliminary CSM diagram for AOI 2 is shown in Figure 6-3
A!

A!

!P

A!

!P

!P

A!

A!

!5 A!

A!

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!

A! A!

A!

A!

A!

A!

A!

A!

A!

A!

A!

A!

A! A! A!

A!

A!

A!

A!

A!

A!

A!

A!

A!

A!

A!

A!!

A!A! A!A! A!A!

A! A! A!

A!

A!

A!

A!

A!

A!

A!

A!

A!

A!

A!A!

A!

A!

A!A!A!

A! A! A!

A!

A!A!

A!

A!

A!

A!

A!

!P

!P !P

!P

!P

!P

!P

!P

!P !P

!P

!P

A!PA!

!P

A!A!

!P

!P

!P

A!

!P

!P!P

!P

!P

A!

AAA!!!

A!A!

A!

A!

A!A!

AAA!!!

A!

A!A!A!AA!!

!P

A!

A!

!P

!P

A!

A!

!P

A!A!A!

A!

!P

A!

A!

A!

A!

A!

A!

A! A!A!

A!

A!

A!

A!

A!

A!

A!

A!

A! A!

A!A! A!

A!

A!

A!A!A!

A! A!

A!

A! A!

A!

A!

A!A!A!

A! A!

A!

A!

!C(

A!

A!

A!A!

A!

A!A!

A!

A!

A!

A!

A!

!P

A!

A!

!P!P

A!AAA!!!

AA!

AA!

AA!!!

A!!

A!!

A!!

A!

AAA!!A!!

!P

A!

!P

!P

!P

!P

!P

!P

!P

!P

!5

!P

!P

!P

!P

!P

!5 !5

!P

!5

!5

!5

!5

!P

!P

!P

!P

!P

!P

!P

!P

!P !P

!P

!P

!P !P

!P

!P

!P

!P

!P

!P

!P

!P

!P

!P

!P

!P

!P !P

!P

!P

!P

!P

A!

!P

!P

!P

!P

!P

!P

!P

A!

A!

A!

A!

A!

East Toll Gate Creek

Highlin e Canal

W est Toll Gate Creek

SandCreek

Lake

Williams

Coal Creek

Watershed

Toll Gate

Creek

Watershed

Sand Creek

Watershed

Aurora Fire

Station No. 9

IRP Site 3 - Former

Base Landfill

Aurora Fire

Station No. 8

F-16 Crash

Location

Former Fire

Station No. 2

FTA No. 2

F-5 Crash

Location

FTA No. 3

Hangar 801

AOI 1

AOI 2

0 1,250 2,500 5,000

Feet

A!

A!

A! A! A!

A!

A!

A!

A!

A!

A!

A!

A!

A!

A! A!

A!

A!

A!

A!

A! A!

A!

!P

E ast Toll Gate Creek

Toll Gate

Creek

Watershed

Sand Creek

Watershed

Building 1520

Building 1515 Building 1500

Building 1000

Building 1511A Building 1004

Building 1005

Hangar 909

GSE Building

Area

Building 1510

Former Tri-Max

Storage Area

Stormwater Retention Pond

Surface Impoundment

AOI 1

AOI 2

­ Figure 6-1

CLIENT

REVISED

SCALE

PROJECT

ARNG

Preliminary Assessment for PFAS at Buckley AASF, CO

4/14/2020

4/14/2020

4/14/2020

MS

JW

RG

GIS BY

CHK BY

PM

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

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

4/14/2020

1:30,000

C:\Users\stankevichm\OneDrive - AECOM Directory\ARNG_PFAS_GIS_60552172\MXDs\CO\Buckley_AASF_Figures\Buckley_AASF_PA_Figures\Fig_6-1_Buckley_AASF_AOI.mxd

Area of Interest

Potential PFAS Release

No Suspected Release

Digitized_water_features

Facility Boundary

Water Body

River/Stream

Canal/Ditch

Pipeline

Surface Water Flow Direction

Inferred Groundwater Flow Direction

!P Domestic

!P Commercial

!5 Industrial

!5 Irrigation

A! Monitoring/Sampling

!C( Municipal

A! Other/Unknown

Area of Interest

12420 Milestone Center Drive

Germantown, MD 20876

0 300 600 1,200

Feet

Aurora WWTP 

Approx 6 miles

25
Media

SOURCE PATHWAY RECEPTOR

AOI 1 –

Building 

1510

Potential HEF 

release from fire 

suppression 

system

PFAS in 

Surface 

Soil / Paved 

Surfaces and 

Sanitary 

Sewers

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

AOI 1 – Building 1510

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

Tresspasser/

Recreational User

Tresspasser/

Recreational User

Notes:

1. The resident and recreational user

receptors refer to an off-site resident and

recreational user.

2. The site worker and construction worker 

receptors refer only to COARNG Buckley AASF 

site and construction workers.

3. Dermal contact exposure pathway is 

incomplete for PFAS.

Flow-Chart Stops

26
Media

SOURCE PATHWAY RECEPTOR

AOI 2 –

Former TriMax Storage

Area

Potential

incidental AFFF

releases as a

result of Tri-Max

storage

PFAS in

Surface

Soil / Paved

Surfaces

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

Incomplete Pathway

Potentially Complete Pathway

Complete Pathway

Site

Worker

Construction

Worker Resident

Site

Worker

Construction

Worker Resident

/ / / /

/ / / /

LEGEND

/ / / /

/ / / /

/ / / /

Figure 6-3

Preliminary Conceptual Site Model

AOI 2 – Former Tri-Max Storage Area

Potential

Off-Facility

Source Not

under

Control of

ARNG

Tresspasser/

Recreational User

Tresspasser/

Recreational User

Notes:

1. The resident and recreational user

receptors refer to an off-site resident and

recreational user.

2. The site worker and construction worker

receptors refer only to COARNG Buckley AASF

site and construction workers.

3. Dermal contact exposure pathway is

incomplete for PFAS.

Flow-Chart Stops

27
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, Colorado

28

7. Conclusions and Data Uncertainty

This report presents a summary of available information gathered during the PA on the use and 

storage of AFFF and other PFAS-related activities at the COARNG Buckley AASF facility. The PA 

findings are based on personnel interviews, environmental investigations and reports, and 

historical documents (Appendix A and Appendix B).

Findings

Two AOIs related to potential PFAS releases were identified at Buckley AASF based on PA data 

(Figure 7-1) and are summarized in Table 7-1 below:

Table 7-1: AOIs at Buckley AASF

Area of Interest Name Used by Potential Release Dates

AOI 1 Building 1510 COARNG 2006, 2019

AOI 2 Former Tri-MaxTM Storage Area COARNG Unknown - 2019

Based on the possible PFAS releases at AOI 2 and the uncertain content of High Expansion Foam 

at AOI 1, there is potential for exposure to PFAS contamination in surface soil to site and 

construction workers, and trespassers via ingestion and inhalation; in subsurface soil to 

construction workers via ingestion and inhalation; and in surface water to site construction 

workers and off-facility recreational users via ingestion. There is also the potential for residents to 

consume produce grown off-facility that has been exposed to PFAS via the agricultural use of 

biosolids for fertilizer generated at the Robert W. Hite Treatment Facility and potentially containing 

PFAS from impacted wastewater from the facility. Additionally, domestic and irrigation wells 

downgradient of Buckley AASF create a potentially complete pathway for PFAS exposure to offfacility residents via ingestion of groundwater. Numerous adjacent sources were identified where 

PFAS releases to the environment occurred outside of the COARNG property boundary. The 

preliminary CSM for AOIs identified at Buckley AASF are shown on Figure 6-2 and Figure 6-3.

The following areas discussed in Section 2 and Section 3 were determined to have no suspected 

PFAS releases to the environment (Table 7-1):

Table 7-2: No Suspected Release Areas

No Suspected 

Release Area Used by Rationale for No Suspected Release Determination

Building 1511A COARNG

Despite the storage of empty Tri-MaxTM units within Building 

1511A, no available information indicates that AFFF or HEF 

has been used or released at this location.

Building 1500 COARNG Readily available information indicates no evidence of

HEF/AFFF stored or use at this location.

Building 1515 COARNG Readily available information indicates no evidence of

HEF/AFFF use at this location.

Building 1000 COARNG Readily available information indicates no evidence of

HEF/AFFF stored or use at this location.

Building 1005 COARNG Readily available information indicates no evidence of

HEF/AFFF stored or use at this location.
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, Colorado

29

No Suspected 

Release Area Used by Rationale for No Suspected Release Determination

Flight Ramp COARNG Readily available information indicates no evidence of 

HEF/AFFF stored or use at this location.

Uncertainties

A number of information sources were investigated 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 ARNG on the storage, use, or disposition of AFFF. 

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

environmental reports, EDRsTM 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 could not be verified with 

corresponding facility documents. Gathered information has a degree of uncertainty due to the 

absence of written documentation, the limited number of personnel with direct knowledge, the 

time passed since PFAS were first used by the ARNG (1969 to present), and a reliance on 

personal recollection. Inaccuracies may arise in potential PFAS storage and use locations. 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.

In order to minimize the level of uncertainty, readily available data regarding storage of PFAS 

were reviewed, tenured personnel were interviewed, and multiple persons were interviewed for 

the same potential source area.

Table 7-3 summarizes the uncertainties associated with areas identified within the COARNG 

property:

Table 7-3: Sources of Uncertainty

Location Source of Uncertainty

Building 1510 Although Jet-X 2 3⁄4% HEF concentrate does not list PFAS compounds on its 

SDS, the SDS only lists hazardous components, and does not definitively 

state that it does not contain PFAS compounds. It is unknown if Jet-X 2 3⁄4% 

HEF escaped via runoff or on the feet of staff during the system release. 

Additionally, it is unknown how plastic sheeting used to confine HEF released 

was disposed of.

Building 1515 Historical aerial imagery indicates that the area currently comprising Building 

1515 was previously used for material storage. It is unknown what type of 

materials were previously stored in this area.

Building 1500 Building 1500 was constructed in 1977. The collective tenure of COARNG 

interviewees available for this PA spans 1995-present. There is a data gap 

between the construction of Building 1500 and the knowledge of COARNG 

interviewees.

Building 1000 Historical aerial imagery shows Building 1000 being constructed between 

1984 and 1991. A data gap exists between the construction of Building 1000 

and the knowledge of COARNG interviewees (1984-1995) .

Building 1005 Historical aerial imagery shows Building 1005 being constructed circa 1994. A 

data gap exists between the construction of Building 1005 and the knowledge 

of COARNG interviewees (1994-1995).
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, Colorado

30

Flight Ramp COARNG interviewees stated that the fire department performs occasional 

water salutes on the flight ramp. It is unknown whether the fire department 

vehicles used to perform water salutes also carry AFFF. Also, there is a data 

gap regarding possible incidents on the ramp prior to 1994.

Former TriMaxTM Storage 

Area

It is unknown how long the Tri-MaxTM units were stored in this area prior to their 

disposal in September 2019.

Potential Future Actions

Interviews with COARNG staff (whose collective tenure span from 1995 to 2000 and 2016 to 

present as employees working at Buckley AASF, and from 1995 to present as COARNG 

employees with knowledge of the facility) indicate that ARNG activities may have resulted in the 

release of AFFF and HEF that may contain PFAS at two AOIs identified during the PA. Based on 

the preliminary CSM developed for the facility, there is potential for PFAS to be exposed to human 

receptors (see Section 7.1). Table 7-4 summarizes the rationale used to determine if the AOIs 

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

Table 7-4: PA Findings Summary

Area of 

Interest AOI Location Rationale Potential Future Action

AOI 1 Building 

1510

39°42'17.21"N; 

104°45'42.64"W

HEF suppression system 

was released during a 

system test in 2006.

Proceed to an SI, focus on 

soil, surface water, sediment, 

and groundwater.

AOI 2 Former 

Tri-MaxTM

Storage Area

39°42'19.82"N; 

104°45'39.18"W

AFFF was formerly stored 

outdoors in Tri-MaxTM units

Proceed to an SI, focus on 

soil, surface water, sediment, 

and groundwater.

ARNG will evaluate the need for an SI at Buckley AASF based on the potential receptors, the 

potential migration of PFAS contamination off the facility, and the availability of resources.
East Toll Gate Creek

Highlin e Canal

W est Toll Gate Creek

SandCreek

Lake

Williams

Aurora Fire

Station No. 9

IRP Site 3 - Former

Base Landfill

Aurora Fire

Station No. 8

F-16 Crash

Location

Former Fire

Station No. 2

FTA No. 2

F-5 Crash

Location

FTA No. 3

Hangar 801

AOI 1

AOI 2

0 1,250 2,500 5,000

Feet

E ast Toll Gate Creek

Building 1520

Building 1515 Building 1500

Building 1000

Building 1511A Building 1004

Building 1005

Hangar 909

GSE Building

Area

Building 1510

Former Tri-Max

Storage Area

Stormwater Retention Pond

Surface Impoundment

AOI 1

AOI 2

­ Figure 7-1

CLIENT

REVISED

SCALE

PROJECT

ARNG

Preliminary Assessment for PFAS at Buckley AASF, CO

4/8/2020

4/8/2020

4/8/2020

MS

JW

RG

GIS BY

CHK BY

PM

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

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

4/8/2020

1:30,000

C:\Users\stankevichm\OneDrive - AECOM Directory\ARNG_PFAS_GIS_60552172\MXDs\CO\Buckley_AASF_Figures\Buckley_AASF_PA_Figures\Fig_7-1_Buckley_AASF_Summary.mxd

Area of Interest

Potential PFAS Release

No Suspected Release

Facility Boundary

Water Body

River/Stream

Canal/Ditch

Pipeline

Summary of Findings

12420 Milestone Center Drive

Germantown, MD 20876

0 300 600 1,200

Feet

Aurora WWTP 

Approx 6 miles

31
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, Colorado

32

8. References

Aerostar SES LLC, 2019. Final Site Inspection Report of Aqueous Film Forming Foam Areas at

Buckley Air Force Base, Arapahoe County, Colorado. April 2019.

COARNG, 2017. Spill Prevention, Control and Countermeasure Plan; Army Aviation Support 

Facilities: Buildings 1500, 1510, and 1515. Buckley AFB, Colorado.

FEMA, 2020. FEMA Flood Map Service Center. https://msc.fema.gov/portal/home. Accessed

January 2020.

House Bill 19-1279, 2019 Regular Session (Co. 2019). Concerning the use of Perfluoroalkyl and

Polyfluoroalkyl Substances, and, in Connection Therewith, Making an Appropriation.

http://leg.colorado.gov/bills/hb19-1279. Approved June 3, 2019.

HydroGeoLogic, Inc., 2015. Final Preliminary Assessment Report for Perfluorinated Compounds

at Buckley Air Force Base, Aurora, Colorado. August 2015.

Metro Wastewater Reclamation District, 2020. Metro Wastewater Reclamation District – Our

Facilities Webpage. http://www.metrowastewater.com/aboutus/Pages/facilities.aspx. Accessed

January 2020.

National Ground Water Association, 2018. Groundwater and PFAS: State of Knowledge and

Practice. January.

National Oceanic and Atmospheric Administration, 2020. Data Tools: 1981-2010 Normals.

https://www.ncdc.noaa.gov/cdo-web/datatools/normals. Accessed January 2020.

URS, 2007. Final Basewide Preliminary Assessment Report, Buckley Air Force Base, Aurora,

Colorado. February.

United States Environmental Protection Agency (USEPA), 1991. Guidance for Performing

Preliminary Assessments under CERCLA. September.

USEPA, 2014. Record of Decision: Site 3 (Former Base Landfill). Buckley Air Force Base.

Prepared By United States Air Force, 460th Space Wing, Buckley AFB, Colorado. March 2014.

USEPA, 2019. Record of Decision: Site 1 (FT001), Former Fire Training Area 2 - Final. Buckley

Air Force Base. Prepared for United States Air Force, Aurora, Colorado. December 2019.

United States Fish and Wildlife Service (USFWS), 2020. National Wetlands Inventory Mapper.

https://www.fws.gov/wetlands/data/mapper.html. (Accessed December 2019).

Western Regional Climate Center, 2020. Cooperative Climatological Data Summaries: NOAA

Cooperative Stations – Temperature and Precipitation. https://wrcc.dri.edu/cgibin/cliMAIN.pl?co2454. Accessed January 2020.
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, Colorado

Appendix A

Data Resources
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, CO

Data resources will be provided separately on CD. Data resources for Buckley AASF include:

Facility Real Property Documents

· 2000 Department of the Army License Number DACA45-3-00-6082 for National Guard

Purposes

Facility PFAS Material Information

· 2006 Chemguard 3% AFFF C-303 Material Safety Data Sheet

· 2010 Tri-Max Chemguard 3% AFFF C-303 Material Safety Data Sheet

· 2015 Building 1510 Fire Suppression System Test Report

· 2015 Ansul Jet-X 2 3⁄4% HEF Concentrate Data Sheet

· 2017 Building 1510 Fire Suppression System Test Report

· 2017 Ansul Jet-X 2 3⁄4% HEF Concentrate Data Sheet

· 2018 Building 1510 Fire Suppression System Test Report

· 2019 Building 1510 Fire Suppression System Test Report

· 2019 Request for Contractor Triple Rinse of Empty Tri-Max Fire Extinguishers

· 2019 Non-Hazardous Waste Manifest for Disposal of AFFF Concentrate

· Buckley AASF Tri-Max Fire Extinguisher Photo 1

· Buckley AASF Tri-Max Fire Extinguisher Photo 2

· Buckley AASF Tri-Max Fire Extinguisher Photo 3

· Buckley AASF Tri-Max Fire Extinguisher Photo 4

Adjacent Sources Information

· 2014 Record of Decision for Buckley Air Force Base Site 3 (Former Base Landfill)

· 2015 Final Buckley Air Force Base Preliminary Assessment for Perfluorinated Compounds

· 2019 Record of Decision for Buckley Air Force Base Site 1 (FT001), Former Fire Training

Area 2

· 2019 Final Buckley Air Force Base Site Inspection Report of AFFF Part 1

· 2019 Final Buckley Air Force Base Site Inspection Report of AFFF Part 2

Helicopter Fuel Leak Documentation

· 2017 US Marine Helicopter Incident Report Form

· 2017 US Marine Helicopter Leak Photos

Previously Performed PFAS Interviews

· 2019 Interview with Buckley Air Force Base Firefighter

EDRTM Report

· 2020 Buckley AASF EDRTM Report
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, Colorado

Appendix B

Preliminary Assessment Documentation
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, Colorado

Appendix B.1

Interview Records
ARNG Preliminary Assessments for PFAS

Telephone Interviews

Colorado ARNG Facilities: Fort Carson, HAATS, Buckley AASF

18 December 2019

1000 to 1145 hrs

Name Affiliation Facility Role

ARNG NA

CPT ARNG NA

USACE NA

USACE NA

AECOM NA

AECOM NA

AECOM NA

Arcadis NA

Arcadis NA

CPT COARNG Environmental Protection Specialist

COARNG Environmental Compliance Manager

CPT COARNG 153rd Military Police Battalion Sustainment Officer

SGT COARNG Unit Environmental Compliance Officer

SSG COARNG 1157

th Engineer Company Supply Sergeant 

COARNG Environmental Protection Specialist (retired)

1SG COARNG Unit Environmental Compliance Officer at HAATS

COARNG Western Region Maintenance Supervisor at HAATS

COARNG Facility Maintenance Supervisor at Buckley AFB

Buckley AASF Discussion:

SGT (2016-present) – Six TRI-MAXTM units that formerly contained AFFF are 

stored in Building 1511A, the cold storage building. The TRI-MAXTM unit’s contents were 

transferred into drums on September 24, 2019 in the GSE building, which is a part of the larger 

Building 1510. A capture berm was constructed to contain any spills during the event. No AFFF 

was spilled during the emptying of the TRI-MAXTM units into drums. Three drums of AFFF 

concentrate were generated during the event. A private contractor will be used to “triple rinse” the 

TRI-MAXTM units in the future prior to disposal offsite. 

No fire training occurs at Buckley AASF with AFFF. The TRI-MAXTM units were never used in 

fire training at the facility. No joint-training with other airport tenants has ever occurred at the 

facility. Handheld ABC fire training is the only known fire training that occurs on the facility. 

No hard landings/crashes/ emergencies have occurred at the facility that have required the use of 

AFFF during response.
Occasionally water salutes are performed when a retiring pilot lands at the facility. Water salutes 

involve fire trucks spraying water during the aircraft landing, and have been performed on the 

flight ramp at Buckley AASF. 

A marine helicopter leaked oil in front of Building 1500; however, the spill was cleaned with 

sorbent pads and no AFFF was used in response to the spill.

(1995-2000 [COANG stationed at Buckley]; 2001-present [COARNG stationed in 

Centennial, CO]) & (1995-2001 [COARNG at Buckley]; 2001-present [COARNG 

stationed in Centennial, CO]) –Buckley AASF is a tenant of Buckley AFB. As such, the AASF

turns over their waste to Buckley AFB for it to become manifested and disposed of jointly with 

that of Buckley AFB. So, the waste manifests for the disposal of the AFFF transferred from the 

Buckley AASF TRI-MAXTM units may have differing numbers of drums because they were 

disposed of along with waste generated at Buckley AFB. (Waste manifests list 18 drums of AFFFwater and 13 drums of AFFF-soil).

Buckley AASF finished construction in 2006 and was occupied by the COARNG. Since then, no 

known crashes or emergencies have occurred on the property requiring AFFF response. 

Building 1510 is constructed with an HEF fire suppression system. A 55-gallon drum of HEF may 

also be stored in the building HEF room.

Buckley AFB has a crash house with a fire department. Information regarding the airport fire 

department would need to be obtained through their staff. POCs for the Buckley AFB are the RPM 

( , and (719-554-5096). Info regarding the use and storage of AFFF at 

Buckley AFB is unknown to COARNG interviewees.

No known training has occurred with the TRI-MAXTM units at the facility. Interviewees spoke 

with SGT (10 year tenure) who also confirmed that no training has ever been performed 

with trimaxes.

A marine helicopter leaked oil in front of Building 1500 1-2 years ago. Sorbent pads were used to 

clean up the spill. Halon was used in response to the spill. 

CPT (2009-present) – Building 1510 is constructed with an HEF fire suppression 

system containing Jet-X HEF concentrate. The system was tested in 2006 following its installation. 

The system test involved a three minute discharge of HEF (of unknown volume) to the main 

hangar. The test was enclosed, and all HEF released was confined to the building interior. The 

HEF was drained via building floor drains which connect to sanitary system sewers, and ultimately 

lead to the metro water district in the city of Denver. Typically, floor drains connect to an OWS, 

but a diverter was used to ensure HEF bypassed the OWS during the test. No HEF is known to 

have escaped the building during the test. No other tests have been performed that involve the 

release of HEF. The HEF system in the building exhibits no signs of corrosion or leakage. A video 

was provided to AECOM of the event. The containment structures (plastic sheeting around the 

edges of the hangar) appear effective.

Building 1000 is a Readiness Center.
Building 1515 is the UAV hangar and does not have a fire suppression system.

Building 1511A is the Cold Storage Building and has no fire suppression system.

Building 1500 is additional hangar space and has a water fire suppression system. 

Building 1005 is used for staff operations.

There are no groundwater monitoring wells at the facility.

The city of Aurora provides drinking water to Buckley AASF. 

Summary:

• There is no known use of AFFF at Buckley AASF

• 6 TRI-MAXTM units that formerly contained AFFF were emptied in September 2019 into 

drums in the GSE Building, that were then disposed of offsite by Buckley AFB. The empty 

TRI-MAXTM units remain onsite in the Cold Storage Building (Building 1511A).

• Building 1510 has an HEF fire suppression system that was tested once in 2006. The test 

was enclosed, and all HEF drained to sanitary system sewers. HEF is currently stored in 

the suppression system tank and in a 55-gallon drum within the building. No other 

buildings have HEF or AFFF suppression systems.

• Buckley AFB has its own fire department. Any PFAS-related investigation 

information/AFFF use information for Buckley AFB and other airport tenants is unknown 

to COARNG interviewees. 
PFAS Preliminary Assessment Report

Buckley AASF, Aurora, Colorado

Appendix B.2

Conceptual Site Model Information
Preliminary Assessment – Conceptual Site Model Information

Site Name:

Why has this location been identified as a site?

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

Training Events

Have any training events with AFFF occurred at this site?

If so, how often?

How much material was used? Is it 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?

Average rainfall?

Any flooding during rainy season?

Direct or indirect pathway to ditches?

Direct or indirect pathway to larger bodies of water?

Does surface water pond any place on site?

Any impoundment areas or retention ponds?

Any NPDES location points near the site?

How does surface water drain on and around the flight line?

Buckley AASF

The site is located at an airport, and stores and maintains aviation assets.

Yes, the facility is located at Buckley Air Force Base (AFB). Known AFFF releases have 

occurred at Buckley AFB.

No, not at the AASF

NA

NA

Generally north towards surface water retention pond

14.30 inches

None

Direct (stormwater networks, drainage ditches)

Indirect (ditches connect to East Toll Gate Creek)

the surface impoundment, and off-facility at the retention pond

Yes, the surface impoundment east of Bldg 1515

Unknown

To the north and south depending on position
Preliminary Assessment – Conceptual Site Model Information

Groundwater:

Groundwater flow direction?

Depth to groundwater?

Uses (agricultural, drinking water, irrigation)?

Any groundwater treatment systems? 

Any groundwater monitoring well locations near the site?

Is groundwater used for drinking water?

Are there drinking water supply wells on installation?

Do they serve off-post populations?

Are there off-post drinking water wells downgradient 

Waste Water Treatment Plant:

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

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

Do we understand the fate of sludge waste?

Is surface water from potential contaminated sites treated?

Equipment Rinse Water

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

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?

3. Other?

Inferred to flow north

25-30 ft bgs

Groundwater not used on facility.

Not at Buckley AASF

at Buckley AFB

No

No

NA

Numerous wells of various types exist within the vicinity of the Buckley AASF including domestic 

and irrigation wells downgradient of the facility 

No, wastewater is transferred to an off-facility WWTP

NA

Sludge from the Metro WWTP is used at MetroGro Farm

Surface water from the greater Buckley AFB area is treated by the Metro WWTP, which includes 

known AFFF release areas.

Buckley AASF does not store firetrucks, but does have Tri-Max units. No known washing/

rinsing occurs, but a rinsing is scheduled for empty Tri-Max units currently stored onsite.

Nozzle testing does not occur.
Preliminary Assessment – Conceptual Site Model Information

Identify Potential Receptors:

Site Worker 

Construction Worker 

Recreational User

Residential 

Child 

Ecological

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

Documentation

Ask for Engineering drawings (if applicable).

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

Potential receptor of PFAS in surface soil

Potential receptor of PFAS in surface/subsurface soil

Potential receptor of PFAS in surface water off-facility

Potential receptor of PFAS in groundwater downgradient of facility

Potential off-facility receptors if using surface water for recreational purposes

Potential receptors within surface water and surface soil adjacent to the facility

Residential areas approximately 0.6 miles west, elementary schools and daycares 

located more than 1 mile from the facility.

Buckley AASF was constructed in 2006; however, some buildings used by the COARNG 

today pre-date AASF construction. Facility drainage prior to 2006 is unclear.