FINAL

Site Inspection Report 

Austin Bergstrom Army Aviation 

Support Facility

Austin, Texas

Site Inspection for Perfluorooctanoic acid (PFOA), 

Perfluorooctanesulfonic acid (PFOS), Perfluorohexanesulfonic 

acid (PFHxS), Perfluorononanoic acid (PFNA), 

Hexafluoropropylene oxide dimer acid (HFPO-DA), and 

Perfluorobutanesulfonic acid (PFBS) at ARNG Installations, 

Nationwide

June 2023

Prepared for:

Army National Guard Bureau

111 S. George Mason Drive

Arlington, VA 22204

UNCLASSIFIED

Site Inspection Report

Austin Bergstrom Army Aviation Support Facility, Austin, Texas

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Table of Contents

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

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

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

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

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

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

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

2.2.1 Geology ......................................................................................................2-1

2.2.2 Hydrogeology..............................................................................................2-1

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

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

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

2.2.6 Sensitive Habitat and Threatened/ Endangered Species.............................2-3

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

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

3.1 AOI 1 Maintenance Hangar...................................................................................3-1

3.2 AOI 2 Wash Rack..................................................................................................3-1

3.3 AOI 3 Fixed Wing Support Hangar and Storage Hangar .......................................3-1

3.4 AOI 4 Hazardous Materials Storage Building and Fuel Station..............................3-2

3.5 Adjacent Sources ..................................................................................................3-2

3.5.1 Former Bergstrom AFB ...............................................................................3-2

3.5.2 ABIA Fire Station.........................................................................................3-3

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

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

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

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

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

4.5 Data Usability Assessment....................................................................................4-1

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

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

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

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

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

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

5.3 Temporary Well Installation and Groundwater Grab Sampling...............................5-3

5.4 Synoptic Water Level Measurements ....................................................................5-4

5.5 Surveying..............................................................................................................5-4

5.6 Investigation-Derived Waste..................................................................................5-4

5.7 Laboratory Analytical Methods ..............................................................................5-5

5.8 Deviations from SI QAPP Addendum ....................................................................5-5

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

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

6.2 Soil Physicochemical Analyses .............................................................................6-2

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

6.3.2 AOI 1 Groundwater Analytical Results.........................................................6-3

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

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

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

6.4.2 AOI 2 Groundwater Analytical Results.........................................................6-4

6.4.3 AOI 2 Conclusions ......................................................................................6-4

6.5 AOI 3.....................................................................................................................6-4

6.5.1 AOI 3 Soil Analytical Results .......................................................................6-4

6.5.2 AOI 3 Groundwater Analytical Results.........................................................6-5

6.5.3 AOI 3 Conclusions ......................................................................................6-5

6.6 AOI 4.....................................................................................................................6-5

6.6.1 AOI 4 Soil Analytical Results .......................................................................6-5

6.6.2 AOI 4 Groundwater Analytical Results.........................................................6-6

6.6.3 AOI 4 Conclusions ......................................................................................6-6

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

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

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

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

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

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

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

7.2.1 AOI 1...........................................................................................................7-3

7.2.2 AOI 2...........................................................................................................7-3

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

7.2.4 AOI 4...........................................................................................................7-3

7.3 Surface Water and Sediment Exposure Pathway ..................................................7-3

7.3.1 AOI 1...........................................................................................................7-3

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

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

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

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

8.1 SI Activities............................................................................................................8-1

8.2 Outcome ...............................................................................................................8-1

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

Appendix A Data Usability Assessment and Validation Reports

Appendix B Field Documentation

B1. Log of Daily Notice of Field Activities

B2. Sampling Forms

B3. Survey Data

B4. Nonconformance and Corrective Action Report

Appendix C Photographic Log

Appendix D TPP Meeting Minutes

Appendix E Boring Logs

Appendix F Analytical Results

Appendix G Laboratory Reports

Figures

Figure 2-1 Facility Location

Figure 2-2 Facility Topography

Figure 2-3 Groundwater Features

Figure 2-4 Groundwater Elevations, June 2021

Figure 2-5 Surface Water Features

Figure 3-1 Areas of Interest

Figure 5-1 Site Inspection Sample Locations

Figure 6-1 PFOA Detections in Soil

Figure 6-2 PFOS Detections in Soil

Figure 6-3 PFBS Detections in Soil

Figure 6-4 PFHxS Detections in Soil

Figure 6-5 PFNA Detections in Soil

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

Figure 6-7 PFHxS and PFNA Detections in Groundwater

Figure 7-1 Conceptual Site Model, AOI 1 Maintenance Hangar and AOI 4 Hazardous 

Materials Storage Building and Fuel Station

Figure 7-2 Conceptual Site Model, AOI 2 Wash Rack

Figure 7-3 Conceptual Site Model, AOI 3 Fixed Wing Support Hangar and Storage Hangar

Tables

Table ES-1 Screening Levels (Soil and Groundwater)

Table ES-2 Summary of Site Inspection Findings and Recommendations

Table 5-1 Site Inspection Samples by Medium

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

Elevations

Table 6-1 Screening Levels (Soil and Groundwater)

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

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

Table 6-4 PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Groundwater

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

% percent

°F degrees Fahrenheit

μg/kg micrograms per kilogram

AASF Army Aviation Support Facility

ABIA Austin-Bergstrom International Airport

AECOM AECOM Technical Services, Inc.

AFB Air Force Base

AFFF aqueous film-forming foam

AFRC Armed Forces Reserve Center

AOI Area of Interest

ARNG Army National Guard

bgs below ground surface 

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act 

CoC chain of custody

CSM conceptual site model

DA Department of the Army

DoD Department of Defense

DPT direct push technology

DQO data quality objective

DUA data usability assessment

ELAP Environmental Laboratory Accreditation Program

EM Engineer Manual

FedEx Federal Express

FTA Fire Training Area

GPRS Ground Penetrating Radar Systems

HDPE high-density polyethylene 

HFPO-DA hexafluoropropylene oxide dimer acid

IDW investigation-derived waste

ITRC Interstate Technology Regulatory Council

JVMF Joint Vehicle Maintenance Facility

LC/MS/MS liquid chromatography with tandem mass spectrometry

MIL-SPEC military specific

MS matrix spike

MSD matrix spike duplicate

NELAP National Environmental Laboratory Accreditation Program

ng/L nanograms per liter

OSD Office of the Secretary of Defense

OWS oil-water separator

PA Preliminary Assessment

PAL Project Action Limit

PFAS per- and polyfluoroalkyl substances

PFBS perfluorobutanesulfonic acid

PFHxS perfluorohexanesulfonic acid
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PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

PID photoionization detector

PQAPP Programmatic UFP-QAPP

PVC polyvinyl chloride

QA quality assurance 

QAPP Quality Assurance Project Plan

QC quality control

QSM Quality Systems Manual

RI Remedial Investigation

SI Site Inspection

SL screening level

SOP standard operating procedure

SWMU Solid Waste Management Unit

TCEQ Texas Commission on Environmental Quality

TOC total organic carbon

TPP Technical Project Planning

TXARNG Texas Army National Guard

UFP Uniform Federal Policy

US United States

USACE United States Army Corps of Engineers

USAF United States Air Force

USCS Unified Soil Classification System

USEPA United States Environmental Protection Agency

USFWS United States Fish and Wildlife Service 

USGS United States Geological Survey 
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Executive Summary

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

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

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

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

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

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

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

, and perfluorobutanesulfonic acid 

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

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

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

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

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

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

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

relevant compounds. This SI was completed at the Austin Bergstrom Army Aviation Support 

Facility (AASF) in Austin, Texas and determined further investigation is warranted for each of the 

four AOIs. The Austin Bergstrom AASF will also be referred to as the “facility” throughout this 

document.

The Austin Bergstrom AASF occupies approximately 57 acres of land at the Austin Bergstrom 

International Airport in Austin, Texas. The facility includes three hangars, a Joint Vehicle 

Maintenance Facility, and an Armed Forces Reserve Center. The Austin Bergstrom AASF is 

tasked with providing hangar, administrative, and supply and maintenance shop spaces to service 

aircraft, serve peacetime missions, and perform the necessary tasks that improve the units’ 

readiness. 

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

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

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

for each of the four AOIs. 

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

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

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

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

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

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

Analyteb

Residential

(Soil)

(μg/kg)a 

0-2 feet bgs

Industrial/ Commercial 

Composite Worker

(Soil)

(μg/kg)a 

2-15 feet bgs

Tap Water

(Groundwater)

(ng/L)a

PFOA 19 250 6

PFOS 13 160 4 

PFBS 1,900 25,000 601 

PFHxS 130 1,600 39

PFNA 19 250 6

Notes:

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

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

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

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

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

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

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

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

AOI Potential

Release Area

Soil – 

Source Area

Groundwater – 

Source Area

Groundwater –

Facility 

Boundary

Future Action

1 Maintenance Hangar Proceed to RI 

2 Wash Rack Proceed to RI

3

Fixed Wing Support 

Hangar Proceed to RI

Storage Hangar Proceed to RI

4 

Hazardous Materials 

Storage Building Proceed to RI

Fuel Station Proceed to RI

Legend:

N/A = not applicable 

= detected; exceedance of the screening levels

= detected; no exceedance of the screening levels

= not detected
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1. Introduction

1.1 Project Authorization

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

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

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

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

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

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

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

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

, and perfluorobutanesulfonic

acid (PFBS) at ARNG facilities nationwide. The ARNG performed this SI at the Austin Bergstrom 

Army Aviation Support Facility (AASF) in Austin, Texas. The Austin Bergstrom AASF is also

referred to as the “facility” throughout this document.

The SI project elements were performed in compliance with Comprehensive Environmental 

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

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

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

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

investigations.

1.2 SI Purpose

A PA was performed at Austin Bergstrom AASF (AECOM Technical Services, Inc. [AECOM], 

2020) that identified four Areas of Interest (AOIs) where PFAS-containing materials may have 

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

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

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

threats, or no further action is required based on screening levels (SLs) for the relevant 

compounds. 

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

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

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

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

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

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

2.1 Facility Location and Description

Austin Bergstrom AASF, home to the Texas ARNG (TXARNG), is within the southwest portion of 

the Austin-Bergstrom International Airport (ABIA) in Austin, Texas. The facility is 8 miles southeast 

of downtown Austin and is situated at the intersection of Burleson Road and Emma Browning 

Avenue (Figure 2-1). TXARNG leases approximately 57 acres of land at ABIA. The facility 

consists of three hangars (a Fixed Wing Support Hangar, Maintenance Hangar, and a Storage 

Hangar), which were built in 2003-2004, as well as a Joint Vehicle Maintenance Facility (JVMF) 

and an Armed Forces Reserve Center (AFRC), which were built in 2011-2012. The Austin 

Bergstrom AASF is tasked with providing hangar, administrative, and supply and maintenance 

shop spaces to service aircraft, serve peacetime missions, and perform the necessary tasks that 

improve the units’ readiness.

2.2 Facility Environmental Setting

Austin Bergstrom AASF is in central Texas, approximately 150 miles northwest of the Gulf of 

Mexico. The facility is situated approximately 2.8 miles southwest of the Colorado River, with 

Onion Creek running along the southern boundary. The facility is located at approximately 500 

feet above sea level, and the soil is described as silty clay with moderate infiltration rates 

(Environmental Data Resources, Inc.TM, 2019). The topography of the facility is generally level, 

sloping slightly to the south (Figure 2-2).

2.2.1 Geology

Austin is located along the Balcones Fault Zone, with the physiographic provinces of the Edwards 

Plateau to the west, and the Backland Prairie to the east. The regional geology consists of 

Quaternary terrace deposits over Cretaceous sedimentary bedrock (Young, 1977).

The facility is underlain by Quaternary fluviatile terrace deposits composed of gravel, sand, silt, 

and clay (Garner and Young, 1976; Texas Bureau of Economic Geology, 1981; US Geological 

Survey [USGS], 1993). An SI performed at the Former Bergstrom Air Force Base (AFB), located 

1-mile north of the facility, interpreted the terrace deposits as being composed of predominantly

clay up to 26 feet below ground surface (bgs) before transitioning into a clayey gravel for an 

additional 4 feet (Amec Foster Wheeler, 2016). The Cretaceous-aged Navarro and Taylor Groups 

underly the terrace deposits. These units are similar and are often undivided when mapped. The 

Navarro Group is composed of dark gray to brown, silty, calcareous, montmorillonitic clay, 

whereas the Taylor Group is described as dark gray to green-gray, calcareous, montmorillonitic 

clay (Garner and Young, 1976). The geology at the facility is shown on Figure 2-3. 

Soil borings completed during the SI found lean clay with sand and gravel as the dominant 

lithology of the unconsolidated sediments below the Austin Bergstrom AASF. The borings were 

completed at depths between 24 and 28 feet bgs. Layers of sand, gravel, and silt were also 

observed in the boring logs at thicknesses ranging from a few inches to several feet. These 

observations are consistent with the understood fluviatile terrace depositional environment.

Boring logs are presented in Appendix E. 

2.2.2 Hydrogeology

The facility is underlain by the regional Trinity Aquifer, which is about 1,500 feet bgs (Garner and 

Young, 1976; Texas Water Development Board, 2011). The Trinity Aquifer extends across much 

of the central and northeastern part of the state and is composed of several smaller aquifers 
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contained within the Trinity Group. These aquifers consist of limestones, sands, clays, gravels, 

and conglomerates. The Trinity Aquifer is one of the most extensive and highly used groundwater 

resources in Texas. Although its primary use is for municipalities, the Trinity Aquifer is also used 

for irrigation, livestock, and other domestic purposes. The Trinity Aquifer is confined by the 

Navarro-Del Rio confining unit, which consists of the Navarro Group, Taylor Group, Austin Group, 

Eagle Ford Group, Buda Limestone, and Del Rio Clay and is typically greater than 1,200-feet thick 

(Barker and Ardis, 1996).

Groundwater at Austin Bergstrom AASF is first encountered in the shallow unconfined aquifer 

within the terrace deposits. The wells near the facility are likely screened in shallow terrace or 

alluvial deposits. Groundwater in the shallow fluviatile terrace deposits aquifer is present within 

the clayey gravel, at a depth of approximately 20 to 25 feet bgs. Recharge primarily occurs 

through percolation from the surface and through stream channels. Groundwater flow in the 

shallow aquifer has been measured to the east and northeast at FT023P, a fire training area (FTA) 

operated by the former Bergstrom AFB and located approximately 1 mile north of the facility 

(Amec Foster Wheeler, 2016). A groundwater gradient determination was conducted at the former 

Bergstrom AFB in 1995 and found that groundwater at the Austin Bergstrom AASF flows to the 

south-southeast. The variation in flow direction in the vicinity of the facility is considered to be 

primarily related to the thickness of the terrace deposits above the Taylor Marl (Law 

Environmental, Inc., 1995).

The facility obtains its drinking water from the City of Austin, which acquires water from surface 

water intakes from the lower Colorado River as it flows through Lake Travis and Lake Austin. A 

query of the Texas Water Development Board Submitted Driller’s Reports Database identified one 

industrial water supply well, 4 domestic wells, and 27 monitoring wells within a 1-mile radius of 

the facility. The industrial water supply well is 35 feet bgs and is located southeast of the facility. 

The four domestic wells are located between 0.3 and 0.6 miles northeast and southeast of the 

facility and range from 35 to 70 feet bgs. The majority of the monitoring wells are located to the 

south of the facility, along the perimeter of the Travis County Landfill. Additionally, there are four 

monitoring wells to the northwest of the facility that are owned by Sunland Group; the monitoring 

wells are between 26 and 121.5 feet bgs. Wells within a 4-mile radius are shown on Figure 2-3. 

Depths to water measured in June 2021 during the SI ranged from 14.36 to 19.21 feet bgs. 

Groundwater elevation contours from the SI are presented on Figure 2-4 and indicate 

groundwater flow direction is generally to the southeast.

2.2.3 Hydrology 

After reviewing the Topography and Storm Water Drainage System (ABIA, 2019) and the 

engineering drawings of the 24-inch and 30-inch reinforced concrete pipe Discharge Outlet Plans 

(Jose I. Guerra, Inc., 2010), it was determined that surface water collects on the paved area to 

the west of the Maintenance Hangar and flows via large diameter underground piping south to 

the holding tank and oil-water separator (OWS) (Figure 2-5). Water then flows to the northeast, 

where it joins with other storm water from contributing portions of the north side of the facility. The 

comingled storm water then travels through underground piping to the JVMF Complex Pond. The 

JVMF Complex Pond consists of a water quality pond and a retention pond. After the storm water 

moves through the retention pond, it flows southwest through underground piping to the AFRC 

Pond. From the AFRC Pond, storm water from light rain events flowed to Outfall #2, which is 

located to the east of General Aviation Avenue. At Outfall #2, storm water was discharged and 

allowed to infiltrate into the subsurface. This outfall was capped and removed from service in 

2018. During heavier rain events, water flows to Outfall #1, located south of Burleson Road, and 

is discharged to Onion Creek. Although rainwater may have carried contaminants to Outfalls #1 

and #2, it is more likely that AFFF release events resulted in contaminants collecting in the JVMF 

Complex Pond and the AFRC Pond and penetrating the subsurface in these two areas.
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In addition, it was determined from on-site interviews that wastewater that collects in the wash 

rack either flows to the storm water drainage system (described above) or flows through an 

oil/sand filter and then discharges to the sanitary sewer system. The position of the diverter valve 

at the wash rack determines whether wastewater flow travels to the storm water drainage system 

or to the sanitary sewer.

2.2.4 Climate 

The climate of Austin is humid subtropical, with hot summers and mild winters, and with warm 

spring and fall transitional periods. Temperatures reach their peak in August, with normal highs 

ranging from 95 degrees Fahrenheit (°F) to 98°F in 2021, and lows averaging 73°F. Average 

annual rainfall is approximately 36 inches, with May, October, and June typically being the wettest 

months of the year (National Weather Service Forecast Office, 2022). Precipitation in the spring 

and summer usually results from thunderstorms (National Oceanic and Atmospheric 

Administration, 2022).

2.2.5 Current and Future Land Use

The Austin Bergstrom AASF currently includes three aircraft hangars. The facility also houses the 

JVMF and the AFRC. Current land use in the direct vicinity of the Austin Bergstrom AASF includes 

the ABIA to the north (formerly the Bergstrom AFB) and a park to the south, across Burleson 

Road. To the east and west is mostly undeveloped land. The Travis County Landfill is located 

approximately 0.5 miles southwest of the facility. No future changes to the current use were noted 

during personnel interviews.

2.2.6 Sensitive Habitat and Threatened/ Endangered Species 

The following birds, plants, mammals, and reptiles are federally endangered, threatened, 

proposed, and/ or are listed as candidate species in Travis County, Texas (US Fish and Wildlife 

Service [USFWS], 2022). 

• Amphibians: Barton Springs salamander, Eurycea sosorum (endangered); Austin blind

Salamander, Eurycea waterlooensis (endangered); Jollyville Plateau Salamander, Eurycea

tonkawae (threatened); Georgetown Salamander, Eurycea naufragia (threatened)

• Arachnids: Bone Cave harvestman, Texella reyesi (endangered); Tooth Cave Spider,

Neoleptoneta myopica (endangered); Bee Creek Cave harvestman, Texella reddelli

(endangered); Tooth Cave pseudoscorpion, Tartarocreagris texana (endangered)

• Birds: Red knot, Calidris cantus rufa (threatened); Golden-cheeked warbler, Dendroica

chrysoparia (endangered); Piping Plover, Charadrius melodus (threatened); Whooping

crane, Grus Americana (endangered)

• Insects: Monarch butterfly, Danaus plexippus (candidate); Kretschmarr Cave mold beetle,

Texamaurops reddelli (endangered); Tooth Cave ground beetle, Rhadine persephone

(endangered)

• Clams: Texas fawnsfoot, Truncilla macrodon (proposed threatened); Guadalupe Orb,

Cyclonaias necki (proposed endangered); false spike, Fusconaia mitchelli (proposed

endangered); Texas pimpleback Quadrula petrina (proposed endangered); Texas

fatmucket, Lampsilis bracteata (proposed endangered)

• Flowering plants: Bracted twistflower, Streptanthus bracteatus (proposed threatened)
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2.3 History of PFAS Use

Six potential release areas where AFFF may have been used or released historically were 

identified at the Austin Bergstrom AASF during the PA (AECOM, 2020). Austin Bergstrom AASF 

includes three hangars: Maintenance Hangar, Fixed Wing Support Hangar, and Storage Hangar. 

All three hangars are equipped with fire suppression systems that utilized AFFF. Two releases of 

AFFF at the Maintenance Hangar have been recorded, in 2005 during a test of the fire 

suppression system and again in 2006 when a faulty sensor triggered the fire suppression system. 

Although there are no recorded releases of AFFF at the Fixed Wing Support Hangar or the 

Storage Hangar, it is believed both systems were tested in 2005 when the systems were installed, 

leading to a potential release of AFFF. Between 2005 and 2010, mobile fire extinguishers 

containing AFFF were stored near the Wash Rack. In 2009, AFFF was released at the Wash Rack 

during fire training activities. Additionally, AFFF has historically been stored at the Hazardous

Materials Storage Building and the Fuel Station. No known releases of PFAS-containing material 

have been recorded at either area. The potential release areas were grouped into four AOIs, 

which are described in Section 3. 
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Facility Location

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Groundwater Features

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and the GIS User Community

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Stream/River

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Alluvium

Fluvial Terrace Deposits

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Groundwater Elevations, 

June 2021

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and the GIS User Community

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Joint Vehicle 

Maintenance Facility 

Complex Pond

Armed Forces

Reserve Center Pond

Maintenance

Hangar

AECOM 2-9
Site Inspection Report

Austin Bergstrom Army Aviation Support Facility, Austin, Texas

AECOM 2-10

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Site Inspection Report

Austin Bergstrom Army Aviation Support Facility, Austin, Texas

AECOM 3-1

3. Summary of Areas of Interest

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

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

identified at Austin Bergstrom AASF and grouped into four AOIs (AECOM, 2020). The potential 

release areas are shown on Figure 3-1. 

3.1 AOI 1 Maintenance Hangar

AOI 1 is the Maintenance Hangar, which is used for helicopter maintenance. The Maintenance 

Hangar has a fire suppression system consisting of two 800-gallon AFFF tanks and a 100-gallon 

AFFF tank. In 2005, AFFF was released during testing of the newly installed fire suppression 

system. After testing, the foam was allowed to settle and was then pushed down the trench drain. 

The trench drain conveyed the foam to the holding tank, then the OWS, and then to the storm 

water drainage system.

On 13 February 2006, a faulty sensor triggered the fire suppression system and resulted in a 

release of AFFF that filled the hangar with approximately 5 feet of foam. Foam and water were 

directed to the holding tank on the south side of the complex. A third-party contractor pressure 

washed and cleaned the hangar, sampled/analyzed the spill residue and contents of the holding 

tank, pumped out the holding tank, and stored the solution in frac tanks to prevent rain from 

increasing the volume of solution in the holding tank. Once this task was completed, and the 

waste was characterized, the contractor disposed of the material. While AFFF was captured at 

the holding tank, it is possible an unknown quantity of AFFF solution may have been released to 

the storm water drainage system before corrective measures were taken during the release. The 

material released during the spill was recorded as being Jet-X 2.75 percent (%) AFFF. While there 

is a record of the handling of the AFFF produced during the accidental release, there is no record 

of the handling and disposal of the AFFF produced from the first release in 2005. It is assumed 

that some quantity of AFFF was released into the storm water drainage system during both 

releases. Additionally, evidence of past AFFF spills on the sides of the 800-gallon tanks were 

observed during a visual site inspection, but no floor drains were observed in the room.

Water entering the storm water drainage system would flow to the JVMF Complex Pond, then to 

the AFRC Pond. Prior to 2018, surface water from the AFRC Pond was then conveyed to Outfall 

#2 during light storm events. During heavier events, water would have been conveyed to Outfall 

#1 into Onion Creek.

3.2 AOI 2 Wash Rack

AOI 2 is the Wash Rack. From 2005 to 2010, approximately 15 mobile Tri-MaxTM units containing 

AFFF were present on site. In 2009, training activities occurred once or twice with a single TriMaxTM unit. An unknown quantity of AFFF was released during these fire training events. Liquid 

that reaches the wash rack either travels to the holding tank, OWS, and storm water drainage 

system or is diverted to the oil/sand filter and sanitary sewer system, depending on the positioning 

of a diverter valve. The position of the diverter valve at the time of AFFF training is unknown. In 

2009 or 2010, the Tri-MaxTM units were replaced with Purple K units. The AFFF was containerized 

and removed from the facility by a contractor.

3.3 AOI 3 Fixed Wing Support Hangar and Storage Hangar

AOI 3 encompasses the Fixed Wing Support Hangar and the Storage Hangar. These two hangars 

are located approximately 1,000 feet apart but are grouped in the same AOI because of their 

similar site histories. Both hangars are equipped with AFFF fire suppression systems. One 100-
Site Inspection Report

Austin Bergstrom Army Aviation Support Facility, Austin, Texas

AECOM 3-2

gallon tank, two 300-gallon tanks, and four 55-gallon drums of 3% AFFF are stored within the 

storage room of the Fixed Wing Support Hangar. The Storage Hangar fire suppression system is 

connected to one 100-gallon tank and two 800-gallon tanks. Evidence of spillage on the sides of 

the larger tanks in both hangars was observed during a visual site inspection. No floor drains were 

observed in either storage room where bulk AFFF was stored.

3.4 AOI 4 Hazardous Materials Storage Building and Fuel Station

AOI 4 encompasses the Hazardous Materials Storage Building and the Fuel Station. The 

Hazardous Materials Storage Building historically contained 105 5-gallon sealed containers of 

AFFF, and the Fuel Station historically had AFFF-containing Tri-MaxTM units stationed around the 

area. No known releases of any PFAS-containing materials occurred in either area.

3.5 Adjacent Sources

3.5.1 Former Bergstrom AFB

The former Bergstrom AFB is located directly north of the Austin Bergstrom AASF. A Site 

Investigation of potential release areas conducted in 2014 at the former AFB revealed that 

firefighting training activities at the base were conducted from 1942 to 1991 at FT023P, located 

approximately 1 mile north of the facility. FT023P consisted of one fire training pit, approximately 

200 feet in diameter, with a circular berm and limestone lining (Amec Foster Wheeler, 2016).

Surface and subsurface soil samples were collected and analyzed for PFAS at FT023P. The six 

PFAS reported were detected above the limit of quantitation in all three soil locations and indicated 

that PFAS were present across the soil column in both shallow (0-2 feet bgs) and in deeper soil 

(greater than 2 feet to 35 feet bgs). No results were above the US Air Force (USAF) Project Action 

Limits (PALs) for PFOA (12,000 μg/kg) and PFAS (5,000 μg/kg). At the time of the Site 

Investigation, no USAF PALs had been developed for PFHxS, PFBS or PFNA (Amec Foster 

Wheeler, 2016).

In groundwater, PFOA and PFOS were detected above their USAF PALs of 400 ng/L and 200 

ng/L, respectively, at each of the five locations tested, indicating that PFAS have migrated through 

FTA soils into underlying groundwater. FT023P is underlain by terrace deposits consisting of clay 

from the surface to approximately 26 feet bgs, then approximately 5.5 feet of silty to clayey gravel. 

Clay potentially associated with the Upper Taylor Marl bedrock unit was interpreted as being 

present underneath the gravel sediment. However, Cretaceous bedrock in Austin is highly faulted, 

and the bedrock unit underlying the FTA is uncertain. Local groundwater supply comes primarily 

from the regional groundwater aquifer (Edwards Aquifer – Balcones Fault Zone), which occurs at 

about 1,000 feet bgs at the FTA and is not likely to be impacted by the fire training activities. 

Shallow groundwater occurs in the fluviatile terrace deposits and is not used at the facility for 

water supply, but it has domestic uses 1 mile to the south and southeast of the FTA (Amec Foster 

Wheeler, 2016).

A PFAS PA was conducted by Amec Foster Wheeler in December 2015 to determine whether and 

where AFFF was stored, handled, used, or released at the former Bergstrom AFB, in areas other 

than FT023P (Amec Foster Wheeler, 2015). The locations identified in that report are shown on 

Figure 3-1 and include the following:

1) Former Building 201 (Fire Station): Facility stored and potentially used AFFF; however, no

AFFF releases were documented.

2) Former Building 203 (Fire Station Vehicle Wash Rack): Facility was used to wash emergency

vehicles and included a 400-gallon OWS, with effluent drainage to the sanitary sewer system.
Site Inspection Report

Austin Bergstrom Army Aviation Support Facility, Austin, Texas

AECOM 3-3

3) STOR-604 (Base Supply Open Storage Area/Solid Waste Management Unit [SWMU]-153) and 

Former Building 604 (Base Hazardous Storage Facility): Open storage area with a building that 

stored 55-gallon drums and five-gallon containers of AFFF, with a documented AFFF release 

inside the building in 1993.

4) Former Discharge Detention Basin (SWMU-223): Unlined basin designed to contain a full

discharge of AFFF from the fire suppression systems in Hangars 1608 and former Hangar 1609, 

with three documented AFFF releases.

5) Hangar 1608 (Regional Corrosion Control Facility) and STOR-1608 (Storage of Hazardous

Waste): Hangar 1608 maintained an AFFF fire suppression system with two documented 

releases. Storage facility STOR-1608 likely stored AFFF; however, no AFFF releases were 

documented.

6) Former Hangar 1609 (Small Aircraft Maintenance Dock): Hangar maintained an AFFF fire

suppression system with two documented releases.

7) Building 4577 (Crash Fire Station/Vehicle Maintenance Building): Facility may have been used

as a crash fire station; however, no documentation of AFFF storage or use was found.

3.5.2 ABIA Fire Station 

In 1999, the City of Austin was conveyed a deed notice for 942 acres of the former AFB for the 

development of the ABIA. The ABIA Fire Station, approximately 1.4 miles north-northeast of the 

facility, stores AFFF and houses four firetrucks that all use AFFF. AFFF is tested at the Austin Fire 

Department training facility at 4800 Shaw Lane, approximately 2 miles west-northwest of the 

facility. Additionally, Federal Aviation Administration inspections include the use of AFFF at 

unspecified locations around the airport. The last inspection occurred in 2019 and included the 

use of AFFF, although efforts were made to mitigate the foam.
Site Inspection Report

Austin Bergstrom Army Aviation Support Facility, Austin, Texas

AECOM 3-4

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Areas of Interest

12420 Milestone Center Drive ­ Germantown, MD 20876

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AECOM 3-6

Site Inspection Report

Austin Bergstrom Army Aviation Support Facility, Austin, Texas
Site Inspection Report

Austin Bergstrom Army Aviation Support Facility, Austin, Texas

AECOM 4-1

4. Project Data Quality Objectives

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

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

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

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

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

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

AOIs.

4.1 Problem Statement

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

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

SLs are presented in Section 6.1 of this report.

4.2 Information Inputs

Primary information inputs included:

• The PA/SI for the former Bergstrom AFB (Amec Foster Wheeler, 2015; Amec Foster

Wheeler, 2016);

• The PA for Austin Bergstrom AASF (AECOM, 2020);

• Analytical data from groundwater and soil samples collected as part of this SI in accordance

with the site-specific Uniform Federal Policy (UFP)-QAPP Addendum (AECOM, 2021a); and

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

parameters measured at the time of sampling.

4.3 Study Boundaries

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

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

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

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

time field resources were available to complete the study.

4.4 Analytical Approach

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

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

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

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

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

4.5 Data Usability Assessment

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

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

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

methods, the assessment determines whether project execution and the resulting data have met 
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Austin Bergstrom Army Aviation Support Facility, Austin, Texas

AECOM 4-2

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

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

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

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

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

requirements of the SI QAPP Addendum (AECOM, 2021a). 
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AECOM 5-1

5. Site Inspection Activities

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

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

in accordance with the following approved documents: 

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

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

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

• Final Preliminary Assessment Report, Austin Bergstrom Army Aviation Support Facility,

Austin, Texas dated July 2020 (AECOM, 2020);

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

Austin Bergstrom Army Aviation Support Facility, Austin, Texas dated April 2021 (AECOM,

2021a); and

• Final Site Safety and Health Plan, Austin Bergstrom Army Aviation Support Facility, Austin,

Texas dated June 2021 (AECOM, 2021b).

The SI field activities were conducted from 7 to 10 June 2021 and consisted of utility clearance,

direct push boring, soil sample collection, temporary monitoring well installation, grab groundwater 

sample collection, and land surveying. Field activities were conducted in accordance with the SI 

QAPP Addendum (AECOM, 2021a), except as noted in Section 5.8. 

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

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

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

• Twenty-eight (28) soil samples from 15 boring locations;

• Six grab groundwater samples from six temporary well locations; and

• Fifteen (15) quality assurance (QA)/quality control (QC) samples.

Figure 5-1 provides the sample locations for all media across the facility. Table 5-1 presents the 

list of samples collected for each media. Field documentation is provided in Appendix B. A Log 

of Daily Notice of Field Activity was completed throughout the SI field activities, which is provided 

in Appendix B1. Sampling forms are provided in Appendix B2, land survey data are provided in 

Appendix B3, and a Nonconformance and Corrective Action Report is provided in Appendix B4. 

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

5.1 Pre-Investigation Activities

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

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

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

5.1.1 Technical Project Planning

The US Army Corps of Engineers (USACE) TPP Process, Engineer Manual (EM) 200-1-2 

(USACE, 2016) defines four phases to project planning: 1.) defining the project phase; 2.) 

determining data needs; 3.) developing data collection strategies; and 4.) finalizing the data 

collection plan. The process encourages stakeholder involvement in the SI, beginning with 
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AECOM 5-2

defining overall project objectives, including DQOs, and formulating a sampling approach to 

address the AOIs identified in the PA. 

A combined TPP Meeting 1 and 2 was held on 5 January 2021, prior to SI field activities. The 

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

stakeholders for this SI include the ARNG, TXARNG, USACE, Texas Commission on 

Environmental Quality (TCEQ), and representatives familiar with the facility, the regulations, and 

the community. Stakeholders were provided the opportunity to make comments on the technical 

sampling approach and methods at the combined TPP Meeting 1 and 2. The outcome of the 

combined TPP Meeting 1 and 2 was memorialized in the SI QAPP Addendum (AECOM, 2021a).

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

for TPP 3 are included in Appendix D of this report. Future TPP meetings will provide an 

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

5.1.2 Utility Clearance 

AECOM’s drilling subcontractor, WEST Drilling placed a ticket with the Texas811 utility clearance 

provider to notify them of intrusive work on 16 April 2021. Additionally, AECOM contracted Ground 

Penetrating Radar Systems (GPRS), a private utility location service, to perform utility clearance. 

GPRS performed utility clearance of the proposed boring locations on 3 June and 7 June 2021 

with input from the AECOM field team and Austin Bergstrom AASF facility staff. General locating 

services and ground-penetrating radar were used to complete the clearance. Additionally, the first 

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

subsurface where utilities would typically be encountered. 

5.1.3 Source Water and Sampling Equipment Acceptability

A potable water source at Austin Bergstrom AASF was sampled on 28 April 2021 to assess 

usability for decontamination of drilling equipment. Results of the sample collected (ABF-PW-01) 

confirmed this source to be acceptable for use in this investigation; therefore, it was used 

throughout the field activities. Specifically, the samples were analyzed by LC/MS/MS compliant 

with QSM 5.3 Table B-15. The results of the decontamination water sample used during the SI 

are provided in Appendix F. A discussion of the results is presented in the DUA (Appendix A).

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

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

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

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

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

member regarding the allowable materials within the sampling environment. 

5.2 Soil Borings and Soil Sampling

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

surfaces. Soil samples were collected via direct push technology (DPT), in accordance with the 

SI QAPP Addendum (AECOM, 2021a). A GeoProbe® 4822T dual-tube sampling system was used 

to collect continuous soil cores to the target depth. A hand auger was used to collect soil from the 

top 5 feet of the boring, in accordance with AECOM utility clearance procedures. The soil boring 

locations are shown on Figure 5-1 and depths are provided Table 5-1. 

In general, three discrete soil samples were collected from the vadose zone for chemical analysis 

from each soil boring: one surface soil sample (0 to 2 feet bgs), one subsurface soil sample 
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AECOM 5-3

approximately 2 feet above the groundwater table, and one subsurface soil sample at the midpoint between the surface and the groundwater table. 

The soil cores were continuously logged for lithological descriptions by an AECOM field geologist 

using the Unified Soil Classification System (USCS). A photoionization detector (PID) was used 

to screen the breathing zone during boring activities as part of personal safety requirements. 

Observations and measurements were recorded on boring logs (Appendix E) and in a nontreated field logbook (i.e., composition notebook). Depth interval, recovery thickness, PID 

concentrations, moisture, relative density, color (using a Munsell soil color chart), and texture 

(using the USCS) were recorded. 

Soil borings completed during the SI found lean clay with sand and gravel as the dominant 

lithology of the unconsolidated sediments below the Austin Bergstrom AASF. The borings were 

completed at depths between 24 and 28 feet bgs. Layers of sand, gravel, and silt were also 

observed in the boring logs at thicknesses ranging from a few inches to several feet. These 

observations are consistent with the understood depositional environment of the region.

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

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

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

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

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

SI QAPP Addendum (AECOM, 2021a).

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

as the accompanying samples. Matrix spike (MS)/MS duplicates (MSDs) were collected at a rate 

of 5% and analyzed for the same parameters as the accompanying samples. In instances when 

non-dedicated sampling equipment was used, such as a hand auger for the shallow soil samples, 

equipment rinsate blanks were collected at a rate of 5% and analyzed for the same parameters 

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

preserved at or below 6 degrees Celsius during shipment.

DPT borings were converted to temporary wells, which were subsequently abandoned in 

accordance with the SI QAPP Addendum (AECOM, 2021a) using bentonite chips at completion 

of sampling activities.

5.3 Temporary Well Installation and Groundwater Grab Sampling

Temporary wells were installed using a GeoProbe® 4822T DPT drilling rig equipped with hollow 

stem auger capabilities to accommodate the installation of 2-inch well casing. Once the borehole 

was advanced to the desired depth, a temporary well was constructed of a 5-foot section of 2-

inch Schedule 40 poly-vinyl chloride (PVC) screen with sufficient casing to reach ground surface. 

New PVC pipe and screen were used to avoid cross contamination between locations. The screen 

intervals for the temporary wells are provided in Table 5-2. 

Groundwater samples were collected after a period of time following well installation to allow 

groundwater to infiltrate and recharge the temporary well screen intervals. After the recharge 

period, groundwater samples were collected using a bladder pump with PFAS-free HDPE tubing. 

The temporary wells were purged at a rate determined in the field to reduce turbidity and draw 

down prior to sampling. Water quality parameters (e.g., temperature, specific conductance, pH, 

dissolved oxygen, and oxidation-reduction potential) were measured using a water quality meter 

and recorded on the field sampling form (Appendix B2) before each grab sample was collected. 

Additionally, a subsample of each groundwater sample was collected in a separate container, and 

a shaker test was completed to identify if there were any foaming. No foaming was noted in any 

of the groundwater samples.
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AECOM 5-4

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

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

standard CoC procedures to the laboratory and analyzed by LC/MS/MS compliant with QSM 5.3

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

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

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

same parameters as the accompanying samples. One field reagent blank was collected in 

accordance with the PQAPP (AECOM, 2018a). A temperature blank was placed in each cooler to 

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

Following well surveying (described below in Section 5.5), temporary wells were abandoned in 

accordance with the SI QAPP Addendum (AECOM, 2021a) by removing the PVC and backfilling 

the hole with bentonite chips. Upon completion of well abandonment, the ground surface at each 

location was patched to match existing surrounding conditions.

5.4 Synoptic Water Level Measurements

A synoptic groundwater gauging event was performed between 7 June to 10 June 2021. 

Groundwater elevation measurements were collected from the six new temporary monitoring 

wells. Water level measurements were taken from the northern side of the well casing. A 

groundwater flow contour map is provided in Figure 2-4. Groundwater elevation data are provided 

in Table 5-2. 

5.5 Surveying

The northern side of each well casing was surveyed by Texas-licensed land surveyors following 

guidelines provided in the SOPs provided in the SI QAPP Addendum (AECOM, 2021a). Survey 

data from the newly installed wells on the facility were collected on 10 June 2021 in the applicable 

Universal Transverse Mercator 14 zone projection with World Geodetic System 84 datum 

(horizontal) and North American Vertical Datum 1988 (vertical). The surveyed well data are

provided in Appendix B3. 

5.6 Investigation-Derived Waste

As of the date of this report, the disposal of investigation-derived waste (IDW) is not regulated 

federally. IDW generated during the SI is considered non-hazardous waste and was managed in 

accordance with the SI QAPP Addendum (AECOM, 2021a) and with the DA Guidance for 

Addressing Releases of PFAS, Q18 (DA, 2018). 

Soil IDW (i.e., drill cuttings) generated during SI activities were containerized in properly labeled 

55-gallon drums and stored next to the Hazardous Materials Storage Containers at the facility.

ARNG G-9 will manage disposal of the solid IDW and will coordinate with TXARNG to ensure 

proper disposal in accordance with Army Guidance for Addressing Releases of PFAS, Q18 (DA, 

2018).

Liquid IDW (i.e., purge water and decontamination fluids) generated during SI activities was 

containerized in properly-labeled 55-gallon drums and stored next to the Hazardous Materials 

Storage Containers at the facility. The liquid IDW will not be sampled and will assume the PFAS 

characteristics of the associated groundwater samples collected from the source locations. The 

containerized IDW will be temporarily stored onsite until the analytical results for the associated 

groundwater samples are available. ARNG G-9 will manage and dispose of the liquid IDW under 

a separate contract in accordance with SOP No. 042A for Treating Liquid Investigation-Derived 

Material (purge water, drilling water, and decontamination fluids) (EA Engineering, Science, and 
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AECOM 5-5

Technology, Inc., 2021). ARNG will further coordinate with TCEQ to ensure proper disposal and 

the Army Guidance for Addressing Releases of PFAS, Q18 (DA, 2018).

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

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

activities were disposed of at a licensed solid waste landfill.

5.7 Laboratory Analytical Methods

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

Coast in Baton Rouge, Louisiana, a DoD ELAP and NELAP certified laboratory. Soil samples 

were also analyzed for TOC using USEPA Method 9060A and pH by USEPA Method 9045D.

5.8 Deviations from SI QAPP Addendum

One deviation from the SI QAPP Addendum was identified during review of the field 

documentation. The deviation is noted below and is documented in Nonconformance and 

Corrective Action Report (Appendix B4):

• Upon review of field documentation, it was discovered that soil sample AO01-01-SB28 collected for grain size analysis was inadvertently not logged in by the lab during

sample check in and therefore, not analyzed. The SI QAPP Addendum states that

grain size analysis would be performed in up to one soil sample per AOI where

extensive horizontal and vertical clay units are identified by the field geologist, if these

conditions are encountered in the field. As a result, AECOM will use information from

the photo log and boring logs to understand geologic conditions at the facility.

Additionally, this discrepancy does not affect the determination of whether further

investigation of the AOI is needed in a Remedial Investigation. This action was

documented in a nonconformance and corrective action report provided in Appendix

B4.

782
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AECOM 5-6

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Table 5-1

Site Inspection Samples by Medium

Site Inspection Report, Austin Bergstrom AASF, Austin, Texas

Sample Identification

Sample

Collection 

Date/Time

Sample Depth 

(feet bgs) LC/MS/MS compliant with QSM 5.3 Table B-15 TOC (USEPA Method 9060A) pH (USEPA Method 9045D) Grain Size (ASTM D-422) Comments

AOI01-01-SB-00-02 6/9/2021 12:50 0-2 x

AOI01-01-SB-06-08 6/9/2021 13:30 6-8 x

AOI01-01-SB-06-08-D 6/9/2021 13:30 6-8 x Field Duplicate

AOI01-01-SB-13-15 6/9/2021 14:00 13-15 x x x

AOI01-01-SB-13-15-D 6/9/2021 14:00 13-15 x x x Field Duplicate

AOI01-01-SB-13-15-MS 6/9/2021 14:00 13-15 x x x MS/MSD

AOI01-01-SB-13-15-MSD 6/9/2021 14:00 13-15 x x x MS/MSD

AOI01-01-SB-28 6/9/2021 14:30 28 x

AOI01-02-SB-00-02 6/7/2021 16:00 0-2 x

AOI01-02-SB-00-02-D 6/7/2021 16:00 0-2 x Field Duplicate

AOI01-02-SB-00-02-MS 6/7/2021 16:00 0-2 x MS/MSD

AOI01-02-SB-00-02-MSD 6/7/2021 16:00 0-2 x MS/MSD

AOI02-01-SB-00-02 6/7/2021 9:18 0-2 x x x

AOI02-02-SB-00-02 6/7/2021 9:50 0-2 x

AOI02-03-SB-00-02 6/7/2021 10:20 0-2 x

AOI03-01-SB-00-01 6/8/2021 11:30 0-1 x

AOI03-02-SB-00-01 6/8/2021 12:00 0-1 x x x

AOI03-03-SB-00-02 6/7/2021 15:10 0-2 x

AOI04-01-SB-00-02 6/8/2021 15:40 0-2 x x x

AOI04-02-SB-00-02 6/8/2021 15:10 0-2 x

ABF-01-SB-00-02 6/8/2021 11:55 0-2 x

ABF-01-SB-07-09 6/8/2021 12:40 7-9 x

ABF-01-SB-13-15 6/8/2021 12:35 13-15 x

ABF-02-SB-00-02 6/8/2021 16:00 0-2 x

ABF-02-SB-07-09 6/8/2021 16:30 7-9 x

ABF-02-SB-13-15 6/8/2021 16:25 13-15 x

ABF-03-SB-00-02 6/9/2021 8:45 0-2 x

ABF-03-SB-07-09 6/9/2021 9:20 7-9 x

ABF-03-SB-13-15 6/9/2021 9:15 13-15 x

ABF-04-SB-00-02 6/7/2021 14:40 0-2 x

ABF-04-SB-06-08 6/7/2021 16:05 6-8 x

ABF-04-SB-12-14 6/7/2021 16:00 12-14 x

ABF-05-SB-00-02 6/8/2021 8:08 0-2 x

ABF-05-SB-06-08 6/8/2021 8:50 6-8 x

ABF-05-SB-12-14 6/8/2021 8:45 12-14 x

AOI01-01-GW 6/9/2021 17:40 26.5 x

AOI01-01-GW-D 6/9/2021 17:40 26.5 x Field Duplicate

AOI01-01-GW-MS 6/9/2021 17:40 26.5 x MS/MSD

AOI01-01-GW-MSD 6/9/2021 17:40 26.5 x MS/MSD

ABF-01-GW 6/8/2021 17:50 22.30 x

ABF-02-GW 6/9/2021 10:25 23 x

ABF-03-GW 6/10/2021 7:30 25 x

ABF-04-GW 6/8/2021 9:45 24 x

ABF-05-GW 6/8/2021 14:00 17.81 x

ABF-PW-01 4/28/2021 9:30 NA x Decon Source

ABF-ERB-01 6/7/2021 14:35 NA x Hand Auger

ABF-ERB-02 6/8/2021 12:30 NA x Bladder Pump

ABF-ERB-03 6/9/2021 7:35 NA x Drill Shoe

ABF-FRB-01 6/8/2021 9:32 NA x Field Blank

Notes:

AOI = Area of Interest

AASF = Army Aviation Support Facility

ABF = Austin Bergstrom Facility

ASTM = American Society for Testing and Materials

bgs = below ground surface

D = duplicate

ERB = equipment rinsate blank

FRB = field reagent blank

GW = groundwater

LC/MS/MS = Liquid Chromatography Mass Spectrometry

MS/MSD = matrix spike/ matrix spike duplicate

pH = potential for hydrogen

QSM = Quality Systems Manual

SB = soil boring

TOC = total organic carbon

USEPA = United States Environmental Protection Agency

Soil Samples

Quality Control Samples

Groundwater Samples

AECOM 5-7
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AECOM 5-8

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Table 5-2

Soil Boring Depths, Temporary Well Screen Intervals, and Groundwater Elevations

Site Inspection Report, Austin Bergstrom AASF, Austin Texas

Area of 

Interest

Boring 

Location

Soil Boring 

Depth 

(feet bgs)

Temporary Well 

Screen Interval 

(feet bgs)

Top of Casing 

Elevation 

(feet NAVD88)

Ground Surface 

Elevation 

(feet NAVD88)

Depth to 

Water

(feet btoc)

Depth to 

Water

(feet bgs)

Groundwater 

Elevation

(feet NAVD88)

AOI01-01 28 22.67-27.67 477.03 476.2 19.88 19.05 457.15

AOI01-02 2 NA NA NA NA NA NA

AOI02-01 2 NA NA NA NA NA NA

AOI02-02 2 NA NA NA NA NA NA

AOI02-03 2 NA NA NA NA NA NA

AOI03-01 2 NA NA NA NA NA NA

AOI03-02 1 NA NA NA NA NA NA

AOI03-03 1 NA NA NA NA NA NA

AOI04-01 2 NA NA NA NA NA NA

AOI04-02 2 NA NA NA NA NA NA

ABF-01 24 18.26-23.26 476.64 475.6 17.17 16.13 459.47

ABF-02 25 20.5-25.5 474.65 473.7 17.48 16.53 457.17

ABF-03 25 20.18-25.18 473.47 473.4 17.65 17.58 455.82

ABF-04 25 19.32-24.32 476.18 475.0 20.39 19.21 455.79

ABF-05 24 12.0-17.0 472.61 470.8 16.17 14.36 456.44

Notes:

AOI = Area of Interest

AASF = Army Aviation Support Facility

ABF = Austin Bergstrom Facility

bgs = below ground surface

btoc = below top of casing

NA = not applicable

NAVD88 = North American Vertical Datum 1988

Facility 

Boundary

2

1

3

4

AECOM 5-9
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AECOM 5-10

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ABF-02

ABF-03

ABF-04

ABF-05

AOI01-01

AOI01-02

AOI02-01

AOI02-02 AOI02-03

AOI03-01

AOI03-02

AOI03-03

AOI04-01

AOI04-02

CLIENT

REVISED

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GIS BY

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PROJECT Site Inspection at Austin Bergstrom AASF, TX

8/1/2022

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12420 Milestone Center Drive

Germantown, MD 20876

Site Inspection Sample Locations

Base Map: Source: Esri, Maxar, Earthstar Geographics,

and the GIS User Community

0 150 300 600

Feet

Legend

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"S Surface Soil Sample

Facility Boundary

Water Body

Groundwater Flow Direction

AECOM 5-11
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AECOM 5-12

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AECOM 6-1

 6. Site Inspection Results 

This section presents the analytical results of the SI. The SLs used in this evaluation are 

presented in Section 6.1. A discussion of the results for each AOI is provided in Section 6.3

through Section 6.7. Table 6-2 through Table 6-4 present results in soil or groundwater for the 

relevant compounds. Tables that contain all results are provided in Appendix F, and the 

laboratory reports are provided in Appendix G. 

6.1 Screening Levels

The DoD has adopted a policy to retain facilities in the CERCLA process based on risk-based 

SLs for soil and groundwater, as described in a memorandum from the OSD dated 6 July 2022 

(Assistant Secretary of Defense, 2022). The ARNG program under which this SI was performed 

follows this DoD policy. Should the maximum site concentration for sampled media exceed the 

SLs established in the OSD memorandum, the AOI will proceed to the next phase under CERCLA. 

The SLs established in the OSD memorandum apply to the five compounds presented on Table 

6-1 below.

Table 6-1: Screening Levels (Soil and Groundwater)

Analyteb

Residential

(Soil)

(μg/kg)a 

0-2 feet bgs

Industrial/ 

Commercial 

Composite 

Worker

(Soil)

(μg/kg)a 

2-15 feet bgs

Tap Water

(Groundwater)

(ng/L)a

PFOA 19 250 6 

PFOS 13 160 4

PFBS 1,900 25,000 601 

PFHxS 130 1,600 39

PFNA 19 250 6 

Notes:

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

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

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

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

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

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

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

The data in the subsequent sections are compared against the SLs presented in Table 6-1. The 

SLs for groundwater are based on direct ingestion. The SLs for soil are based on incidental 

ingestion and are applied to the depth intervals reasonably anticipated to be encountered by the 

receptors identified at the facility: the residential scenario is applied to surface soil results (0 to 2 

feet bgs), and the industrial/commercial worker scenario is applied to shallow subsurface soil 

results (2 to 15 feet bgs). The SLs are not applied to deep subsurface soil results (>15 feet bgs) 

because 15 feet is the anticipated limit of construction activities.
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AECOM 6-2

6.2 Soil Physicochemical Analyses

To provide basic soil parameter information, soil samples were analyzed for TOC and pH, which 

are important for evaluating transport through the soil medium. Appendix F contains the results 

of the TOC and pH sampling. 

The data collected in this investigation will be used in subsequent investigations, where 

appropriate, to assess fate and transport. According to the Interstate Technology Regulatory 

Council (ITRC), several important partitioning mechanisms include hydrophobic and lipophobic 

effects, electrostatic interactions, and interfacial behaviors. At relevant environmental pH values, 

certain PFAS are present as organic anions and are therefore relatively mobile in groundwater 

(Xiao et al., 2015), but tend to associate with the organic carbon fraction that may be present in 

soil or sediment (Higgins and Luthy, 2006; Guelfo and Higgins, 2013). When sufficient organic 

carbon is present, organic carbon normalized distribution coefficients (Koc values) can help in 

evaluating transport potential, though other geochemical factors (for example, pH and presence 

of polyvalent cations) may also affect PFAS sorption to solid phases (ITRC, 2018).

6.3 AOI 1 

This section presents the analytical results for soil and groundwater in comparison to SLs for 

AOI 1: Maintenance Hangar. The soil and groundwater results are summarized on Table 6-2

through Table 6-4. Soil and groundwater results are presented on Figure 6-1 through Figure 6-7. 

6.3.1 AOI 1 Soil Analytical Results

Figure 6-1 through Figure 6-5 present the ranges of detections in soil. Table 6-2 through Table 

6-3 summarize the soil results.

Soil was sampled surface soil (0 to 2 feet bgs) from boring locations AOI01-01 and AOI01-02. Soil 

was also sampled from subsurface soil (6 to 8 feet bgs and 13 to 15 feet bgs) from boring location 

AOI01-01. PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in surface soil at 

concentrations below their respective SLs. PFOA was detected at locations AOI01-01 and AOI01-

02, with concentrations of 0.440 J micrograms per kilogram (μg/kg) and 0.888 J μg/kg, 

respectively. PFOS was detected at location AOI01-01, with a concentration of 1.13 J μg/kg. 

PFHxS was detected at location AOI01-01, with a concentration of 0.594 J μg/kg. PFNA was 

detected at locations AOI01-01 and AOI01-02, with concentrations of 0.311 J μg/kg and 0.748 J 

μg/kg, respectively. PFBS was detected at location AOI01-01, with a concentration of 0.051 J 

μg/kg. PFOA, PFOS, PFHxS, PFNA, and PFBS were not detected in subsurface soil. 

Soil was also sampled from surface soil (0 to 2 feet bgs) at the facility boundary locations ABF-01 

through ABF-04. Soil sample ABF-01 was upgradient of AOI 1 and ABF-02 through ABF-04 were 

downgradient of AOI 1. Soil was also sampled from subsurface soil at all four locations with 

intervals of 7 to 9 feet bgs and 13 to 15 feet bgs at ABF-01 through ABF-03, and intervals of 6 to 

8 feet bgs and 12 to 14 feet bgs at ABF-04. PFOA, PFOS, PFHxS, PFNA, and PFBS were 

detected in surface soil at concentrations below their respective SLs. PFOA was detected at all 

four locations, with concentrations ranging from 0.133 J μg/kg to 0.263 J μg/kg. PFOS was 

detected at all four locations, with concentrations ranging from 0.390 J μg/kg to 0.773 J μg/kg. 

PFHxS was detected at three locations (ABF-01, ABF-03, ABF-04), with concentrations ranging 

from 0.079 J μg/kg to 0.115 J μg/kg. PFNA was detected at all four locations, with concentrations 

ranging from 0.027 J μg/kg to 0.065 J μg/kg. PFBS was detected at locations ABF-03 and ABF-04, 

with concentrations of 0.029 J μg/kg and 0.062 J μg/kg, respectively. PFOS and PFHxS were 

detected in subsurface soil at concentrations below their respective SLs. PFOS was detected 

below the SL of 160 μg/kg at location ABF-01 (13 to 15 feet bgs), with a concentration of 2.55 

μg/kg. PFHxS was detected below the SL of 1,600 μg/kg at location ABF-01 (13 to 15 feet bgs), 
Site Inspection Report

Austin Bergstrom Army Aviation Support Facility, Austin, Texas

AECOM 6-3

with a concentration of 0.045 J μg/kg. PFOA, PFNA, and PFBS were not detected in subsurface 

soil. 

6.3.2 AOI 1 Groundwater Analytical Results 

Figure 6-6 and Figure 6-7 present the ranges of detections in groundwater. Table 6-4 

summarizes the groundwater results. 

Within AOI 1, groundwater was sampled from temporary monitoring well location AOI01-01. 

PFOA, PFOS, PFHxS, and PFNA were detected in groundwater at concentrations exceeding their 

respective SLs. PFOA was detected above the SL of 6 nanograms per liter (ng/L), with a maximum 

concentration of 44.8 J+ ng/L in the field duplicate sample (AOI01-01-GW-D). PFOS was detected 

above the SL of 4 ng/L, with a concentration of 578 ng/L. PFHxS was detected above the SL of 

39 ng/L, with a concentration of 240 J+ ng/L. PFNA was detected above the SL of 6 ng/L, with a 

concentration of 9.30 J+ ng/L. PFBS was detected below the SL of 601 ng/L, with a concentration

of 17.7 J+ ng/L. 

Groundwater was also sampled at the facility boundary from four temporary monitoring well 

locations ABF-01 through ABF-04. Groundwater sample ABF-01 was upgradient of AOI 1 and 

ABF-02 through ABF-04 were downgradient of AOI 1. PFOA, PFOS, and PFHxS were detected 

in groundwater at concentrations exceeding their respective SLs. PFOA was detected above the 

SL of 6 ng/L at all four locations, with concentrations ranging from 7.53 ng/L to 24.8 ng/L. PFOS 

was detected above the SL of 4 ng/L at all four locations, with concentrations ranging from 59.2 

ng/L to 273 ng/L. PFHxS was detected above the SL of 39 ng/L at locations ABF-01 and ABF-02, 

with concentrations of 77.4 ng/L to 176 ng/L, respectively. Additionally, PFHxS was detected 

below the SL at locations ABF-03 and ABF-04, with concentrations of 16.2 ng/L and 38.2 ng/L, 

respectively. PFNA was detected below the SL of 6 ng/L at all four locations, with concentrations 

ranging from 2.25 J ng/L to 5.98 ng/L. PFBS was detected below the SL of 601 ng/L at all four 

locations, with concentrations ranging from 1.59 J ng/L to 13.9 ng/L.

6.3.3 AOI 1 Conclusions

Based on the results of the SI, PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in soil 

below their respective SLs. PFOA, PFOS, PFHxS, and PFNA were detected in groundwater at 

concentrations above their respective SLs. Based on the exceedances of the SLs in groundwater, 

further evaluation at AOI 1 is warranted.

6.4 AOI 2 

This section presents the analytical results for soil and groundwater in comparison to SLs for 

AOI 2: Wash Rack. The results in soil and groundwater are summarized on Table 6-2 through 

Table 6-4. Soil and groundwater results are presented on Figure 6-1 through Figure 6-7. 

6.4.1 AOI 2 Soil Analytical Results

Figure 6-1 through Figure 6-5 present the ranges of detections in soil. Table 6-2 through Table 

6-3 summarize the soil results.

Soil was sampled from surface soil (0 to 2 feet bgs) from boring locations AOI02-01, AOI02-02, 

and AOI02-03. PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in surface soil at 

concentrations below their respective SLs. PFOA was detected at location AOI02-01, with a 

concentration of 0.207 J μg/kg. PFOS was detected at all three locations, with concentrations 

ranging from 0.114 J μg/kg to 3.02 μg/kg. PFHxS was detected at all three locations, with 

concentrations ranging from 0.063 J μg/kg to 1.43 μg/kg. PFNA was detected at locations 
Site Inspection Report

Austin Bergstrom Army Aviation Support Facility, Austin, Texas

AECOM 6-4

AOI02-01 and AOI02-03, with concentrations of 0.040 J μg/kg and 0.027 J μg/kg, respectively. 

PFBS was not detected in surface soil. 

Soil was also sampled from surface soil (0 to 2 feet bgs) at facility boundary location ABF-05, 

which was downgradient of AOI 2. Soil was also sampled from subsurface soil at the location with 

intervals of 6 to 8 feet bgs and 12 to 14 feet bgs. PFOS, PFHxS, and PFBS were detected in 

surface soil below their respective SLs. PFOS was detected with a concentration of 0.090 J μg/kg. 

PFHxS was detected with a concentration of 0.038 J μg/kg. PFBS was detected with a 

concentration of 0.025 J μg/kg. PFOA and PFNA were not detected in surface soil. PFOA, PFOS, 

PFHxS, PFNA, and PFBS were not detected in subsurface soil. 

6.4.2 AOI 2 Groundwater Analytical Results 

Figure 6-6 and Figure 6-7 present the ranges of detections in groundwater. Table 6-4 

summarizes the groundwater results. 

Groundwater was sampled at the facility boundary from temporary monitoring well location 

ABF-05, which was downgradient of AOI 2. PFOA, PFOS, and PFNA were detected in 

groundwater, at concentrations exceeding their respective SLs. PFOA was detected above the 

SL of 6 ng/L, with a concentration of 11.9 ng/L. PFOS was detected above the SL of 4 ng/L, with 

a concentration of 591 ng/L. PFNA was detected above the SL of 6 ng/L, with a concentration of 

6.16 ng/L. PFHxS was detected below the SL of 39 ng/L, with a concentration of 35.8 ng/L. PFBS 

was detected below the SL of 601 ng/L, with a concentration of 1.78 J ng/L. 

6.4.3 AOI 2 Conclusions

Based on the results of the SI, PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in soil at 

concentrations below their respective SLs. PFOA, PFOS, and PFNA were detected in 

groundwater downgradient of AOI 2 at concentrations above their respective SLs. Based on the 

exceedances of the SLs in groundwater, further evaluation at AOI 2 is warranted.

6.5 AOI 3 

This section presents the analytical results for soil and groundwater in comparison to SLs for 

AOI 3: Fixed Wing Support Hangar and the Storage Hangar. The results in soil and groundwater

are presented in Table 6-2 through Table 6-4. Soil and groundwater results are presented on 

Figure 6-1 through Figure 6-7. 

6.5.1 AOI 3 Soil Analytical Results

Figure 6-1 through Figure 6-5 present the ranges of detections in soil. Table 6-2 through Table 

6-3 summarize the soil results.

At the Fixed Wing Support Hangar, soil was sampled from surface soil (0 to 2 feet bgs) from boring 

locations AOI03-01 and AOI03-02. PFOA, PFOS, and PFNA were detected in surface soil at 

concentrations below their respective SLs. PFOA was detected at locations AOI03-01 and 

AOI03-02, with concentrations of 0.186 J μg/kg and 0.321 J μg/kg, respectively. PFOS was 

detected at both locations AOI03-01 and AOI03-02, with concentrations of 0.264 J μg/kg and 

0.132 J μg/kg, respectively. PFNA was detected at locations AOI03-01 and AOI03-02, with 

concentrations of 0.096 J μg/kg and 0.232 J μg/kg, respectively. PFHxS and PFBS were not 

detected at either location. 

At the Storage Hangar, soil was sampled from surface soil (0 to 2 feet bgs) from boring location 

AOI03-03. PFOA, PFOS, and PFNA were detected in surface soil at concentrations below their 
Site Inspection Report

Austin Bergstrom Army Aviation Support Facility, Austin, Texas

AECOM 6-5

respective SLs. PFOA was detected with a concentration of 0.336 J μg/kg. PFOS was detected 

with a concentration of 0.324 J μg/kg. PFNA was detected with a concentration of 0.646 J μg/kg. 

PFHxS and PFBS were not detected at AOI03-03. 

Soil was sampled from surface soil (0 to 2 feet bgs) at the facility boundary location ABF-04, which 

was downgradient of AOI 3. Soil was also sampled from subsurface soil at the location with 

intervals of 6 to 8 feet bgs and 12 to 14 feet bgs. PFOA, PFOS, PFHxS, PFNA, and PFBS were

detected in surface soil at concentrations below their respective SLs. PFOA was detected with a 

concentration of 0.133 J μg/kg. PFOS was detected with a concentration of 0.390 J μg/kg. PFHxS 

was detected with a concentration of 0.079 J μg/kg. PFNA was detected with a concentration of 

0.027 J μg/kg. PFBS was detected with a concentration of 0.062 J μg/kg. PFOA, PFOS, PFHxS, 

PFNA, and PFBS were not detected in subsurface soil at ABF-04. 

6.5.2 AOI 3 Groundwater Analytical Results

Figure 6-6 and Figure 6-7 present the ranges of detections in groundwater. Table 6-4 

summarizes the groundwater results. 

Groundwater was sampled at the facility boundary from temporary monitoring well location 

ABF-04, which was downgradient of AOI 3. PFOA and PFOS were detected in groundwater at 

concentrations exceeding their respective SLs. PFOA was detected above the SL of 6 ng/L, with 

a concentration of 7.53 ng/L. PFOS was detected above the SL of 4 ng/L, with a concentration of 

130 ng/L. PFHxS was detected below the SL of 39 ng/L, with a concentration of 38.2 ng/L. PFNA 

was detected below the SL of 6 ng/L, with a concentration of 2.25 J ng/L. PFBS was detected 

below the SL of 601 ng/L, with a concentration of 5.42 ng/L.

6.5.3 AOI 3 Conclusions

Based on the results of the SI, PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in soil at 

concentrations below their respective SLs. PFOA and PFOS were detected in groundwater 

downgradient of AOI 3 at concentrations above their respective SLs. Based on the exceedances 

of the SLs in groundwater, further evaluation at AOI 3 is warranted.

6.6 AOI 4 

This section presents the analytical results for soil and groundwater in comparison to SLs for 

AOI 4: Hazardous Materials Storage Building and Fuel Station. The results in soil and 

groundwater are presented in Table 6-2 through Table 6-4. Soil and groundwater results are 

presented on Figure 6-1 through Figure 6-7. 

6.6.1 AOI 4 Soil Analytical Results

Figure 6-1 through Figure 6-5 present the ranges of detections in soil. Table 6-2 through Table 

6-3 summarize the soil results.

At the Hazardous Materials Storage Building, soil was sampled from surface soil (0 to 2 feet bgs) 

from boring location AOI04-01. PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in surface 

soil at concentrations below their respective SLs. PFOA was detected with a concentration of 

0.611 J μg/kg. PFOS was detected with a concentration of 1.00 J μg/kg. PFHxS was detected 

with a concentration of 0.093 J μg/kg. PFNA was detected with a concentration of 0.042 J μg/kg. 

PFBS was detected with a concentration of 0.038 J μg/kg. 

At the Fuel Station, soil was sampled from surface soil (0 to 2 feet bgs) from boring location 

AOI04-02. PFOA, PFOS, PFHxS, and PFNA were detected in surface soil at concentrations below 
Site Inspection Report

Austin Bergstrom Army Aviation Support Facility, Austin, Texas

AECOM 6-6

their respective SLs. PFOA was detected with a concentration of 0.189 J μg/kg. PFOS was 

detected with a concentration of 0.597 J μg/kg. PFHxS was detected with a concentration of 0.118 

J μg/kg. PFNA was detected with a concentration of 0.054 J μg/kg. PFBS was not detected at 

AOI04-02.

Soil was sampled from surface soil (0 to 2 feet bgs) at the facility boundary locations ABF-01 

through ABF-03. Soil sample ABF-01 was upgradient of AOI 4, and ABF-02 through ABF-03 were 

downgradient of AOI 4. Soil was also sampled from subsurface soil at all three locations, with 

intervals of 7 to 9 feet bgs and 13 to 15 feet bgs. PFOA, PFOS, PFHxS, PFNA, and PFBS were

detected in surface soil at concentrations below their respective SLs. PFOA was detected at all 

three locations, with concentrations ranging from 0.156 J μg/kg to 0.263 J μg/kg. PFOS was 

detected at all three locations, with concentrations ranging from 0.420 J μg/kg to 0.773 J μg/kg. 

PFHxS was detected at locations ABF-01 and ABF-03, with concentrations of 0.115 J μg/kg and 

0.087 J μg/kg, respectively. PFNA was detected at all three locations, with concentrations ranging 

from 0.028 J μg/kg to 0.065 J μg/kg. PFBS was detected at location ABF-03 with a concentration 

of 0.029 J μg/kg. PFOS and PFHxS were detected in subsurface soil at concentrations below 

their respective SLs. PFOS was detected below the SL of 160 μg/kg at location ABF-01 (13 to 15 

feet bgs), with a concentration of 2.55 μg/kg. PFHxS was detected below the SL of 1,600 μg/kg

at location ABF-01 (13 to 15 feet bgs), with a concentration of 0.045 J μg/kg. PFOA, PFNA, and 

PFBS were not detected in subsurface soil. 

6.6.2 AOI 4 Groundwater Analytical Results 

Figure 6-6 and Figure 6-7 present the ranges of detections in groundwater. Table 6-4 

summarizes the groundwater results. 

Groundwater was sampled at the facility boundary from three temporary monitoring well locations,

ABF-01 through ABF-03. Groundwater sample ABF-01 was upgradient of AOI 4 and ABF-02 

through ABF-03 were downgradient of AOI 4. PFOA, PFOS, and PFHxS were detected in 

groundwater at concentrations exceeding their respective SLs. PFOA was detected above the SL 

of 6 ng/L at all three locations, with concentrations ranging from 7.89 ng/L to 24.8 ng/L. PFOS 

was detected above the SL of 4 ng/L at all three locations, with concentrations ranging from 59.2 

ng/L to 273 ng/L. PFHxS was detected above the SL of 39 ng/L at locations ABF-01 and ABF-02, 

with concentrations of 77.4 ng/L and 176 ng/L, respectively. Additionally, PFHxS was detected 

below the SL at location ABF-03, with a concentration of 16.2 ng/L. PFNA was detected below the 

SL of 6 ng/L at all three locations, with concentrations ranging from 3.31 J ng/L to 5.98 ng/L. PFBS 

was detected below the SL of 601 ng/L at all three locations, with concentrations ranging from 

1.59 J ng/L to 13.9 ng/L.

6.6.3 AOI 4 Conclusions

Based on the results of the SI, PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in soil 

below their respective SLs. PFOA, PFOS, PFHxS and PFNA were detected in groundwater 

upgradient and downgradient of AOI 4 at concentrations above their respective SLs. Based on 

the exceedances of the SLs in groundwater, further evaluation at AOI 4 is warranted. 
Table 6-2

PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Surface Soil

Site Inspection Report, Austin Bergstrom Army Aviation Support Facility

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual

Soil, LCMSMS compliant with QSM 5.3 Table B-15 (μg/kg)

PFBS 1900 0.051 J ND UJ ND U ND U ND U ND U ND U ND U ND U 0.038 J

PFHxS 130 0.594 J ND UJ ND U 1.43 0.063 J 0.090 J ND U ND U ND U 0.093 J

PFNA 19 0.311 J 0.055 J 0.748 J 0.040 J ND U 0.027 J 0.096 J 0.232 J 0.646 J 0.042 J

PFOA 19 0.440 J 0.128 J 0.888 J 0.207 J ND U ND U 0.186 J 0.321 J 0.336 J 0.611 J

PFOS 13 1.13 J ND U ND U 3.02 0.114 J 0.306 J 0.264 J 0.132 J 0.324 J 1.00 J

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration ABF Austin Bergstrom Army Aviation Support Facility

U = The analyte was not detected at a level greater than or equal to the adjusted DL AOI Area of Interest

UJ = The analyte was not detected at a level greater than or equal to the adjusted DL. However, the reported adjusted DL is approximate and may be inaccurate or imprecise. D duplicate

DL detection limit

Notes ft feet

Full analytical results for all compounds detected by QSM 5.3 Table B-15, including detection limits, are included in Appendix F. HQ hazard quotient

ID identification

LCMSMS liquid chromatography with tandem mass spectrometry

LOD limit of detection

ND analyte not detected above the LOD

OSD Office of the Secretary of Defense

QSM Quality Systems Manual

Qual interpreted qualifier

SB soil boring

USEPA United States Environmental Protection Agency

μg/kg micrograms per kilogram

06/08/2021

0-1 ft

AOI04

AOI04-01-SB-00-02

06/08/2021

0-2 ft

AOI03-01-SB-00-01

AOI03

AOI03-02-SB-00-01

06/08/2021

0-1 ft

AOI03-03-SB-00-02

06/07/2021

0-2 ft

Area of Interest AOI02

Sample ID

Sample Date

Depth

AOI01

06/09/2021

0-2 ft

AOI01-02-SB-00-02

06/07/2021

0-2 ft

AOI02-03-SB-00-02

06/07/2021

0-2 ft

a. Assistant Secretary of Defense, July 2022. Risk Based Screening Levels Calculated for PFOA, PFOS, PFBS, PFHxS, and PFNA in Groundwater or Soil using

USEPA’s Regional Screening Level Calculator. HQ=0.1, May 2022. Soil screening levels based on residential scenario for incidental ingestion of contaminated soil.

AOI02-02-SB-00-02

06/07/2021

0-2 ft

AOI01-02-SB-00-02-D

06/07/2021

0-2 ft

AOI02-01-SB-00-02

06/07/2021

0-2 ft

AOI01-01-SB-00-02

AECOM 6-7
Table 6-2

PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Surface Soil

Site Inspection Report, Austin Bergstrom Army Aviation Support Facility

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual

Soil, LCMSMS compliant with QSM 5.3 Table B-15 (μg/kg)

PFBS 1900 ND U ND U ND U 0.029 J 0.062 J 0.025 J

PFHxS 130 0.118 J 0.115 J ND U 0.087 J 0.079 J 0.038 J

PFNA 19 0.054 J 0.065 J 0.028 J 0.051 J 0.027 J ND U

PFOA 19 0.189 J 0.184 J 0.263 J 0.156 J 0.133 J ND U

PFOS 13 0.597 J 0.585 J 0.773 J 0.420 J 0.390 J 0.090 J

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration ABF Austin Bergstrom Army Aviation Support Facility

U = The analyte was not detected at a level greater than or equal to the adjusted DL AOI Area of Interest

UJ = The analyte was not detected at a level greater than or equal to the adjusted DL. However, the reported adjusted DL is approximate and may be inaccurate or imprecise. D duplicate

DL detection limit

Notes ft feet

Full analytical results for all compounds detected by QSM 5.3 Table B-15, including detection limits, are included in Appendix F. HQ hazard quotient

ID identification

LCMSMS liquid chromatography with tandem mass spectrometry

LOD limit of detection

ND analyte not detected above the LOD

OSD Office of the Secretary of Defense

QSM Quality Systems Manual

Qual interpreted qualifier

SB soil boring

USEPA United States Environmental Protection Agency

μg/kg micrograms per kilogram

ABF-05-SB-00-02

06/08/2021

0-2 ft

Sitewide

ABF-03-SB-00-02

06/09/2021

0-2 ft

ABF-04-SB-00-02

06/07/2021

0-2 ft

ABF-01-SB-00-02

06/08/2021

0-2 ft

ABF-02-SB-00-02

06/08/2021

0-2 ft

Area of Interest

Sample ID

Sample Date

Depth

a. Assistant Secretary of Defense, July 2022. Risk Based Screening Levels Calculated for PFOA, PFOS, PFBS, PFHxS, and PFNA in Groundwater or Soil using

USEPA’s Regional Screening Level Calculator. HQ=0.1, May 2022. Soil screening levels based on residential scenario for incidental ingestion of contaminated soil.

AOI04

AOI04-02-SB-00-02

06/08/2021

0-2 ft

AECOM 6-8
Table 6-3

PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Shallow Subsurface Soil

Site Inspection Report, Austin Bergstrom Army Aviation Support Facility

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual

Soil, LCMSMS compliant with QSM 5.3 Table B-15 (μg/kg)

PFBS 25000 ND U ND U ND U ND U ND U ND U ND U ND U ND U ND U

PFHxS 1600 ND U ND U ND U ND U ND U 0.045 J ND U ND U ND U ND U

PFNA 250 ND U ND U ND U ND U ND U ND U ND U ND U ND U ND U

PFOA 250 ND U ND U ND U ND U ND U ND U ND U ND U ND U ND U

PFOS 160 ND U ND U ND U ND U ND U 2.55 ND U ND U ND U ND U

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration ABF Austin Bergstrom Army Aviation Support Facility

U = The analyte was not detected at a level greater than or equal to the adjusted DL AOI Area of Interest

D duplicate

Notes DL detection limit

Full analytical results for all compounds detected by QSM 5.3 Table B-15, including detection limits, are included in Appendix F. ft feet

HQ hazard quotient

ID identification

LCMSMS liquid chromatography with tandem mass spectrometry

LOD limit of detection

ND analyte not detected above the LOD

OSD Office of the Secretary of Defense

QSM Quality Systems Manual

Qual interpreted qualifier

SB soil boring

USEPA United States Environmental Protection Agency

μg/kg micrograms per kilogram

Area of Interest

Sample ID

Sample Date

Depth

ABF-01-SB-07-09

06/08/2021

6-8 ft 7-9 ft

AOI01

ABF-03-SB-13-15

06/09/2021

13-15 ft

Sitewide

ABF-02-SB-13-15

06/08/2021

13-15 ft

ABF-03-SB-07-09

06/09/2021

7-9 ft

ABF-01-SB-13-15

06/08/2021

13-15 ft

ABF-02-SB-07-09

06/08/2021

7-9 ft

a. Assistant Secretary of Defense, July 2022. Risk Based Screening Levels Calculated for PFOA, PFOS, PFBS, PFHxS, and PFNA in Groundwater or Soil using

USEPA’s Regional Screening Level Calculator. HQ=0.1, May 2022. Soil screening levels based on industrial/commercial composite worker scenario for incidental

ingestion of contaminated soil.

AOI01-01-SB-13-15-D

06/09/2021

13-15 ft

AOI01-01-SB-06-08-D

06/09/2021

6-8 ft

AOI01-01-SB-13-15

06/09/2021

13-15 ft

AOI01-01-SB-06-08

06/09/2021

AECOM 6-9
Table 6-3

PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Shallow Subsurface Soil

Site Inspection Report, Austin Bergstrom Army Aviation Support Facility

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual

Soil, LCMSMS compliant with QSM 5.3 Table B-15 (μg/kg)

PFBS 25000 ND U ND U ND U ND U

PFHxS 1600 ND U ND U ND U ND U

PFNA 250 ND U ND U ND U ND U

PFOA 250 ND U ND U ND U ND U

PFOS 160 ND U ND U ND U ND U

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration ABF Austin Bergstrom Army Aviation Support Facility

U = The analyte was not detected at a level greater than or equal to the adjusted DL AOI Area of Interest

D duplicate

Notes DL detection limit

Full analytical results for all compounds detected by QSM 5.3 Table B-15, including detection limits, are included in Appendix F. ft feet

HQ hazard quotient

ID identification

LCMSMS liquid chromatography with tandem mass spectrometry

LOD limit of detection

ND analyte not detected above the LOD

OSD Office of the Secretary of Defense

QSM Quality Systems Manual

Qual interpreted qualifier

SB soil boring

USEPA United States Environmental Protection Agency

μg/kg micrograms per kilogram

Area of Interest

Sample ID

Sample Date

Sitewide

ABF-05-SB-12-14

06/08/2021

12-14 ft

ABF-04-SB-12-14

06/07/2021

12-14 ft

ABF-05-SB-06-08

06/08/2021

Depth 6-8 ft

ABF-04-SB-06-08

06/07/2021

6-8 ft

a. Assistant Secretary of Defense, July 2022. Risk Based Screening Levels Calculated for PFOA, PFOS, PFBS, PFHxS, and PFNA in Groundwater or Soil using

USEPA’s Regional Screening Level Calculator. HQ=0.1, May 2022. Soil screening levels based on industrial/commercial composite worker scenario for incidental

ingestion of contaminated soil.

AECOM 6-10
Table 6-4

PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Groundwater

Site Inspection Report, Austin Bergstrom Army Aviation Support Facility

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual

Water, LCMSMS compliant with QSM 5.3 Table B-15 (ng/l)

PFBS 601 16.2 J+ 17.7 J+ 7.51 13.9 1.59 J 5.42 1.78 J

PFHxS 39 209 J+ 240 J+ 77.4 176 16.2 38.2 35.8

PFNA 6 8.27 J+ 9.30 J+ 3.31 J 5.98 3.35 J 2.25 J 6.16

PFOA 6 37.6 J+ 44.8 J+ 16.7 24.8 7.89 7.53 11.9

PFOS 4 501 J 578 111 273 59.2 130 591

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration ABF Austin Bergstrom Army Aviation Support Facility

J+ = Estimated concentration, biased high AOI Area of Interest

D duplicate

Notes GW groundwater

Full analytical results for all compounds detected by QSM 5.3 Table B-15, including detection limits, are included in Appendix F. HQ hazard quotient

ID identification

LCMSMS liquid chromatography with tandem mass spectrometry

LOD limit of detection

ND analyte not detected above the LOD

OSD Office of the Secretary of Defense

QSM Quality Systems Manual

Qual interpreted qualifier

USEPA United States Environmental Protection Agency

ng/l nanogram per liter

Sample Date

ABF-01-GW

06/08/2021

a. Assistant Secretary of Defense, July 2022. Risk Based Screening Levels Calculated for PFOA, PFOS, PFBS, PFHxS, and PFNA in Groundwater or Soil using 

USEPA’s Regional Screening Level Calculator. HQ=0.1, May 2022 Groundwater screening levels based on residential scenario for direct ingestion of groundwater.

Area of Interest AOI01 Sitewide

AOI01-01-GW

06/09/2021

AOI01-01-GW-D

06/09/2021

ABF-04-GW

06/08/2021

ABF-05-GW

06/08/2021

ABF-02-GW

06/08/2021

ABF-03-GW

06/10/2021

Sample ID

AECOM 6-11
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AECOM 6-12

Site Inspection Report

Austin Bergstrom Army Aviation Support Facility, Austin, Texas
Onion Creek

ABF-01

ABF-02

ABF-03

ABF-04

ABF-05

AOI01-01

AOI01-02

AOI02-01

AOI02-02 AOI02-03

AOI03-01

AOI03-02

AOI03-03

AOI04-01

AOI04-02

Onion Creek

ABF-01

ABF-02

ABF-03

ABF-04

ABF-05

AOI01-01

Onion Creek

ABF-01

ABF-02

ABF-03

ABF-04

ABF-05

AOI01-01

­ Figure 6-1

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PFOA Detections in Soil

12420 Milestone Center Drive

Germantown, MD 20876

Facility Boundary

Water Body

Surface Water Flow Direction

Groundwater Flow Direction

Shallow Intermediate Deep

0 180 360 720

Feet

Exceedances of the OSD SL are depicted with a yellow halo.

Depth intervals shown represent respective sampling position within a given soil boring location.

PFOA Results (μg/Kg)

ND

>ND - 19

>19 - 250

>250 - 2,500

>2,500

AECOM 6-13
Onion Creek

ABF-01

ABF-02

ABF-03

ABF-04

ABF-05

AOI01-01

AOI01-02

AOI02-01

AOI02-02 AOI02-03

AOI03-01

AOI03-02

AOI03-03

AOI04-01

AOI04-02

Onion Creek

ABF-01

ABF-02

ABF-03

ABF-04

ABF-05

AOI01-01

Onion Creek

ABF-01

ABF-02

ABF-03

ABF-04

ABF-05

AOI01-01

­ Figure 6-2

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PFOS Detections in Soil

12420 Milestone Center Drive

Germantown, MD 20876

Facility Boundary

Water Body

Surface Water Flow Direction

Groundwater Flow Direction

Shallow Intermediate Deep

0 180 360 720

Feet

Exceedances of the OSD SL are depicted with a yellow halo.

Depth intervals shown represent respective sampling position within a given soil boring location.

PFOS Results (μg/Kg)

ND

>ND - 13

>13 - 160

>160 - 1,600

>1,600

AECOM 6-14
Onion Creek

ABF-01

ABF-02

ABF-03

ABF-04

ABF-05

AOI01-01

AOI01-02

AOI02-01

AOI02-02 AOI02-03

AOI03-01

AOI03-02

AOI03-03

AOI04-01

AOI04-02

Onion Creek

ABF-01

ABF-02

ABF-03

ABF-04

ABF-05

AOI01-01

Onion Creek

ABF-01

ABF-02

ABF-03

ABF-04

ABF-05

AOI01-01

­ Figure 6-3

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PFBS Detections in Soil

12420 Milestone Center Drive

Germantown, MD 20876

Facility Boundary

Water Body

Surface Water Flow Direction

Groundwater Flow Direction

Shallow Intermediate Deep

0 180 360 720

Feet

Exceedances of the OSD SL are depicted with a yellow halo.

Depth intervals shown represent respective sampling position within a given soil boring location.

PFBS Results (μg/Kg)

ND

>ND - 10

>10 - 1,900

>1,900 - 25,000

>25,000

AECOM 6-15
Onion Creek

ABF-01

ABF-02

ABF-03

ABF-04

ABF-05

AOI01-01

AOI01-02

AOI02-01

AOI02-02 AOI02-03

AOI03-01

AOI03-02

AOI03-03

AOI04-01

AOI04-02

Onion Creek

ABF-01

ABF-02

ABF-03

ABF-04

ABF-05

AOI01-01

Onion Creek

ABF-01

ABF-02

ABF-03

ABF-04

ABF-05

AOI01-01

­ Figure 6-4

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PFHxS Detections in Soil

12420 Milestone Center Drive

Germantown, MD 20876

Facility Boundary

Water Body

Surface Water Flow Direction

Groundwater Flow Direction

Shallow Intermediate Deep

0 180 360 720

Feet

Exceedances of the OSD SL are depicted with a yellow halo.

Depth intervals shown represent respective sampling position within a given soil boring location.

PFHxS Results (μg/Kg)

ND

>ND - 10

>10 - 130

>130 - 1,600

>1,600

AECOM 6-15
Onion Creek

ABF-01

ABF-02

ABF-03

ABF-04

ABF-05

AOI01-01

AOI01-02

AOI02-01

AOI02-02 AOI02-03

AOI03-01

AOI03-02

AOI03-03

AOI04-01

AOI04-02

Onion Creek

ABF-01

ABF-02

ABF-03

ABF-04

ABF-05

AOI01-01

Onion Creek

ABF-01

ABF-02

ABF-03

ABF-04

ABF-05

AOI01-01

­ Figure 6-5

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PFNA Detections in Soil

12420 Milestone Center Drive

Germantown, MD 20876

Facility Boundary

Water Body

Surface Water Flow Direction

Groundwater Flow Direction

Shallow Intermediate Deep

0 180 360 720

Feet

Exceedances of the OSD SL are depicted with a yellow halo.

Depth intervals shown represent respective sampling position within a given soil boring location.

PFNA Results (μg/Kg)

ND

>ND - 19

>19 - 250

>250 - 2,500

>2,500

AECOM 6-16
Onion Creek

ABF-01

ABF-02

ABF-03

ABF-04

ABF-05

AOI01-01

ABF-01

ABF-02

ABF-03

ABF-04

ABF-05

AOI01-01

Onion Creek

Onion Creek

ABF-01

ABF-02

ABF-03

ABF-04

ABF-05

AOI01-01

­ Figure 6-6

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PFOA, PFOS, and PFBS Detections in Groundwater

12420 Milestone Center Drive

Germantown, MD 20876

Facility Boundary

Water Body

Surface Water Flow Direction

Groundwater Flow Direction

PFOA PFOS PFBS

0 160 320 640

Feet

PFOS Results (ng/L)

ND

>ND - 4

>4 - 40

>40 - 70

>70

PFOA Results (ng/L)

ND

>ND - 6

>6 - 40

>40 - 70

>70

PFBS Results (ng/L)

ND

>ND - 100

>100 - 601

>601 - 2,000

>2,000

Exceedances of the OSD SL are depicted with a yellow halo.

AECOM 6-17
Onion Creek

ABF-01

ABF-02

ABF-03

ABF-04

ABF-05

AOI01-01

ABF-01

ABF-02

ABF-03

ABF-04

ABF-05

AOI01-01

Onion Creek

­ Figure 6-7

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PFHxS and PFNA Detections in Groundwater

12420 Milestone Center Drive

Germantown, MD 20876

Facility Boundary

Water Body

Surface Water Flow Direction

Groundwater Flow Direction

PFHxS PFNA

0 160 320 640

Feet

PFNA Results (ng/L)

ND

>ND - 6

>6 - 100

>100 - 1,000

>1,000

PFHxS Results (ng/L)

ND

>ND - 39

>39 - 100

>100 - 1,000

>1,000

Exceedances of the OSD SL are depicted with a yellow halo.

AECOM 6-18
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AECOM 6-19

Site Inspection Report

Austin Bergstrom Army Aviation Support Facility, Austin, Texas
Site Inspection Report

Austin Bergstrom Army Aviation Support Facility, Austin, Texas

AECOM 7-1

7. Exposure Pathways

The CSMs for each AOI, revised based on the SI findings, are presented on Figure 7-1 and

Figure 7-2. Please note that while the CSM discussion assists in determining if a receptor may 

be impacted, the decision to move from SI to RI or interim action is determined based upon 

exceedances of the SLs for the relevant compounds and whether the release is more than likely 

attributable to the DoD. A CSM presents the current understanding of the site conditions with 

respect to known and suspected sources, potential transport mechanisms and migration 

pathways, and potentially exposed human receptors. A human exposure pathway is considered 

potentially complete when the following conditions are present:

1. Contaminant source;

2. Environmental fate and transport;

3. Exposure point;

4. Exposure route; and

5. Potentially exposed populations.

If any of these elements are missing, the pathway is incomplete. The CSM figures use an empty 

circle symbol to represent an incomplete exposure pathway. Areas with an incomplete pathway 

generally warrant no further action. However, the pathway is considered potentially complete if the 

relevant compounds are detected, in which case the CSM figure uses a half-filled circle symbol to 

represent a potentially complete exposure pathway. Additionally, a completely filled circle symbol is 

used to indicate when a potentially complete exposure pathway has detections of relevant 

compounds above the SLs. Areas with an identified potentially complete pathway that have 

detections of the relevant compounds above the SLs may warrant further investigation. Although 

the CSMs indicate whether potentially complete exposure pathways may exist, the 

recommendation for future study in a RI or no action at this time is based on the comparison of 

the SI analytical results for the relevant compounds to the SLs.

In general, the potential routes of exposure to the relevant compounds are ingestion and 

inhalation. Human exposure via the dermal contact pathway may occur, and current risk practice 

suggests it is an insignificant pathway compared to ingestion; however, exposure data for dermal 

pathways are sparse and continue to be the subject of toxicological study. The receptors 

evaluated are consistent with those listed in USEPA guidance for risk screening (USEPA, 2001). 

Receptors at the facility include site workers (e.g., facility staff and visiting soldiers), construction 

workers, trespassers, residents outside the facility boundary, and recreational users outside of 

the facility boundary.

7.1 Soil Exposure Pathway

The SI results in soil were used to determine whether a potentially complete pathway exists 

between the source and potential receptors at AOI 1 through AOI 4 based on the aforementioned 

criteria.

7.1.1 AOI 1 

AOI 1 is the Maintenance Hangar, where, in 2005, AFFF was released during testing of a newly 

installed fire suppression system and again in 2006 when a faulty sensor triggered the fire 

suppression system. 
Site Inspection Report

Austin Bergstrom Army Aviation Support Facility, Austin, Texas

AECOM 7-2

PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in surface soil at AOI 1. Site workers, 

construction workers, or trespassers could contact constituents in soil via incidental ingestion, 

and inhalation of dust. Therefore, the surface soil exposure pathway for site workers, future 

construction workers, and trespassers are potentially complete. PFOS and PFHxS were detected 

in shallow subsurface soil at location ABF-01 associated with AOI 1. Construction workers could 

contact constituents in subsurface soil via incidental ingestion and therefore, the subsurface

exposure pathway for future construction workers is potentially complete. No current construction 

is known to be occurring at AOI 1. The CSM for AOI 1 is presented on Figure 7-1. 

7.1.2 AOI 2 

AOI 2 is the Wash Rack, where, between 2005 and 2010, mobile fire extinguishers containing 

AFFF were stored. In 2009, AFFF was released at the Wash Rack during fire training activities. 

PFOA, PFOS, PFHxS, and PFNA were detected in surface soil at AOI 2. Site workers, 

construction workers, or trespassers could contact constituents in surface soil via incidental 

ingestion, and inhalation of dust. Therefore, the surface soil exposure pathway for site workers, 

future construction workers, and trespassers are potentially complete. No current construction is 

known to be occurring at AOI 2. PFOA, PFOS, PFHxS, PFNA, and PFBS were not detected in 

subsurface soil at AOI 2; therefore, all exposure pathways are considered incomplete. The CSM

for AOI 2 is presented on Figure 7-2. 

7.1.3 AOI 3 

AOI 3 consists of the Fixed Wing Support Hangar and the Storage Hangar. Although there are 

no recorded releases of AFFF at the Fixed Wing Support Hangar or the Storage Hangar, it is 

possible both fire suppression systems were tested in 2005 when the systems were installed and 

led to a release of AFFF.

PFOA, PFOS, and PFNA were detected in surface soil at AOI 3. Site workers, construction 

workers, or trespassers could contact constituents in surface soil via incidental ingestion, and

inhalation of dust. Therefore, the surface soil exposure pathway for site workers, future 

construction workers, and trespassers are potentially complete. No current construction is known 

to be occurring at AOI 3. PFOA, PFOS, PFHxS, PFNA, and PFBS were not detected in subsurface 

soil at AOI 3; therefore, all exposure pathways are considered incomplete. The CSM for AOI 3 is 

presented on Figure 7-3. 

7.1.4 AOI 4 

AOI 4 consists of the Hazardous Materials Storage Building and the Fuel Station. Although no 

known releases of PFAS-containing material have been recorded at either area, AFFF has 

historically been stored at the Hazardous Materials Storage Building and the Fuel Station. 

PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in surface soil at AOI 4. Site workers, 

construction workers, or trespassers could contact constituents in surface soil via incidental 

ingestion, and inhalation of dust. Therefore, the surface soil exposure pathway for site workers, 

future construction workers, and trespassers are potentially complete. PFOS and PFHxS were 

detected in shallow subsurface soil at location ABF-01 associated with AOI 4. Construction 

workers could contact constituents in subsurface soil via incidental ingestion and therefore, the 

subsurface exposure pathway for future construction workers is potentially complete. No current 

construction is known to be occurring at AOI 4. The CSM for AOI 4 is presented on Figure 7-1. 
Site Inspection Report

Austin Bergstrom Army Aviation Support Facility, Austin, Texas

AECOM 7-3

7.2 Groundwater Exposure Pathway

The SI results in groundwater were used to determine whether a potentially complete pathway 

exists between the source and potential receptors based on the aforementioned criteria.

7.2.1 AOI 1 

PFOA, PFOS, PFHxS, and PFNA were detected above their respective SLs in groundwater 

samples collected at AOI 1. Additionally, PFOA, PFOS, and PFHxS were detected above their 

respective SLs in groundwater samples collected upgradient and downgradient of AOI 1. Due to 

the presence of downgradient domestic wells within a 4-mile radius of the facility, the ingestion 

exposure pathway is considered potentially complete for off-facility residents. Further, due to the 

depth of groundwater at the AOI (greater than 15 feet bgs), the exposure pathway for future 

construction workers to groundwater is considered incomplete. The CSM for AOI 1 is presented 

on Figure 7-1. 

7.2.2 AOI 2 

PFOA, PFOS, and PFNA were detected above their respective SLs in a groundwater sample 

collected downgradient of AOI 2. Due to the presence of downgradient domestic wells within a 4-

mile radius of the facility, the ingestion exposure pathway is considered potentially complete for 

off-facility residents. Due to the presence of shallow groundwater (less than 15 feet bgs), future 

construction workers may be exposed to contaminated groundwater under trenching scenarios. 

The CSM is presented on Figure 7-2. 

7.2.3 AOI 3 

PFOA and PFOS were detected above their respective SLs in a groundwater sample collected

downgradient of AOI 3. Due to the presence of downgradient domestic wells within a 4-mile radius 

of the facility, the ingestion exposure pathway is considered potentially complete for off-facility 

residents. Further, due to the depth of groundwater at the AOI (greater than 15 feet bgs), the 

exposure pathway for future construction workers to groundwater is considered incomplete. The 

CSM for AOI 3 is presented on Figure 7-1. 

7.2.4 AOI 4 

PFOA, PFOS, and PFHxS were detected above their respective SLs in groundwater samples 

collected upgradient and downgradient of AOI 4. Due to the presence of downgradient domestic 

wells within a 4-mile radius of the facility, the ingestion exposure pathway is considered potentially 

complete for off-facility residents. Further, due to the depth of groundwater at the AOI (greater 

than 15 feet bgs), the exposure pathway for future construction workers to groundwater is 

considered incomplete. The CSM for AOI 4 is presented on Figure 7-1. 

7.3 Surface Water and Sediment Exposure Pathway

The SI results in soil and groundwater, in combination with knowledge of the fate and transport 

properties of PFAS, were used to determine whether a potentially complete pathway exists 

between the source and potential receptors.

7.3.1 AOI 1 

PFAS are water soluble and can migrate readily from soil to surface water via leaching and runoff. Surface water runoff at AOI 1 flows to the south towards Outfall #1 and discharges to Onion 
Site Inspection Report

Austin Bergstrom Army Aviation Support Facility, Austin, Texas

AECOM 7-4

Creek, a tributary to the Colorado River. Additionally, surface water flows to the northeast near 

the Storage Hangar before being routed to the southeast and eventually discharging to the AFRC 

Pond. Overflow from the AFRC pond historically discharged to Outfall #2. Outfall #2 discharged 

to a ditch running along the north side of Burleson Road and north of Onion Creek. Outfall #2 was 

capped, and no water from the AFRC Pond discharges to Outfall #1. Because PFOA, PFOS, 

PFHxS, PFNA, and PFBS were detected in soil and groundwater at AOI 1, it is possible that those 

compounds may have migrated from soil and groundwater to the south, towards Outfall #1 on the 

southern edge of the property via groundwater discharge or surface water runoff. Therefore, the 

surface water and sediment ingestion exposure pathway for site workers, future construction 

workers, or trespassers is considered potentially complete. The Onion Creek ultimately 

discharges to the Colorado River. Due to potential recreational use, the surface water and 

sediment ingestion exposure pathway for off-facility recreational users is considered potentially 

complete. The CSM for AOI 1 is presented on Figure 7-1. 

7.3.2 AOI 2 

Surface water runoff at AOI 2 flows to the south towards Outfall #1 and discharges to Onion Creek, 

a tributary to the Colorado River. Because PFOA, PFOS, PFHxS, PFNA, and PFBS were detected 

in soil and groundwater at AOI 2, it is possible that those compounds may have migrated from 

soil and groundwater to the south, towards Outfall #1 on the southern edge of the property via 

groundwater discharge or surface water runoff. Therefore, the surface water and sediment 

ingestion exposure pathway for site workers, future construction workers, or trespassers is 

considered potentially complete. The Onion Creek ultimately discharges to the Colorado River. 

Due to potential recreational use, the surface water and sediment ingestion exposure pathway for 

off-facility recreational users is considered potentially complete. The CSM for AOI 2 is presented 

on Figure 7-2. 

7.3.3 AOI 3 

Surface water runoff at AOI 3 flows west towards AOI 1 and then south towards Outfall #1 and 

discharges to Onion Creek. Additionally, surface water flows to the northeast near the Storage 

Hangar before being routed to the southeast and discharging to the AFRC Pond and ultimately to 

Onion Creek. Because PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in soil and were 

detected above SLs in groundwater, it is possible that those compounds may have migrated from 

soil and groundwater to the south, towards Outfall #1 on the southern edge of the property via 

groundwater discharge or surface water runoff. Therefore, the surface water and sediment 

ingestion exposure pathway for site workers, future construction workers, or trespassers is 

considered potentially complete. The Onion Creek ultimately discharges to the Colorado River. 

Due to potential recreational use, the surface water and sediment ingestion exposure pathway for 

off-facility recreational users is considered potentially complete. The CSM for AOI 3 is presented 

on Figure 7-3. 

7.3.4 AOI 4 

Similar to AOI 3, surface water runoff at AOI 4 flows west towards AOI 1 and then south towards 

Outfall #1 and discharges to Onion Creek. Additionally, surface water flows to the northeast near 

the Storage Hangar before being routed to the southeast and discharging to the AFRC Pond and 

ultimately to Onion Creek. Because PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in 

soil and were detected above SLs in groundwater, it is possible that those compounds may have 

migrated from soil and groundwater to the south, towards Outfall #1 on the southern edge of the 

property via groundwater discharge or surface water runoff. Therefore, the surface water and 

sediment ingestion exposure pathway for site workers, future construction workers, or trespassers 

is considered potentially complete. The Onion Creek ultimately discharges to the Colorado River. 
Site Inspection Report

Austin Bergstrom Army Aviation Support Facility, Austin, Texas

AECOM 7-5

Due to potential recreational use, the surface water and sediment ingestion exposure pathway for

off-facility recreational users is considered potentially complete. The CSM for AOI 4 is presented 

on Figure 7-1. 
Site Inspection Report

Austin Bergstrom Army Aviation Support Facility, Austin, Texas

AECOM 7-6

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Media

SOURCE PATHWAY RECEPTOR

AOI 1

AOI 4

AFFF Release 

during testing and 

accidental triggering 

of the AFFF fire 

suppression 

system. Potential 

release from AFFF 

storage areas. 

Surface Soil 

Subsurface 

Soil via 

infiltration at 

Retention 

Ponds

Human 

Activities

Leaching/ 

Infiltration

Airborne Soil 

particulate

Surface Soil 

at AOI

Surface 

Water/ 

sediment3 Subsurface 

Soil

Shallow 

Groundwater

Source Release 

Mechanism Media Transport and Migration Media Exposure Routes

Inhalation of 

Dust

Ingestion

Ingestion

Ingestion

Ingestion

Human Receptors: 

Current/ Future

Flow-Chart Continues

Partial / Possible Flow

Flow-Chart Stops

Incomplete Pathway

Potentially Complete Pathway

Potentially Complete Pathway 

with Exceedance of SL

Site Worker Construction Worker2 Resident1 Trespasser/ Recreational User

Site Worker Construction Worker2 Resident1 Trespasser/ Recreational User

/

/

LEGEND

/ /

/ / /

Figure 7-1

Conceptual Site Model

AOI 1 Maintenance Hangar and AOI 4 Hazardous Materials Storage 

Building and Fuel Station

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

/

/

/

/

/

/ /

/

/

Note: 

1. The residential receptor refers

to an off-facility receptor. 

2. No current active construction

at the facility.

3. Precipitation/run-off flows

through the facility's stormwater 

system and retention ponds before 

discharging to Onion Creek, a 

tributary of the Colorado River..

/

Precipitation/ 

Run-Off / /

/

7-7
Media

SOURCE PATHWAY RECEPTOR

AOI 2

AFFF Release 

during AFFF fire 

extinguisher testing/

training. Potential 

release from AFFF 

storage areas. 

Surface Soil 

Subsurface 

Soil via 

infiltration at 

Retention 

Ponds

Human 

Activities

Leaching/ 

Infiltration

Airborne Soil 

particulate

Surface Soil 

at AOI

Surface 

Water/ 

sediment3 Subsurface 

Soil

Shallow 

Groundwater

Source Release 

Mechanism Media Transport and Migration Media Exposure Routes

Inhalation of 

Dust

Ingestion

Ingestion

Ingestion

Ingestion

Human Receptors: 

Current/ Future

Flow-Chart Continues

Partial / Possible Flow

Flow-Chart Stops

Incomplete Pathway

Potentially Complete Pathway

Potentially Complete Pathway 

with Exceedance of SL

Site Worker Construction Worker2 Resident1 Trespasser/ Recreational User

Site Worker Construction Worker2 Resident1 Trespasser/ Recreational User

/

/

LEGEND

/ /

/ / /

Figure 7-2

Conceptual Site Model

AOI 2 Wash Rack

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

/

/

/

/

/

/ /

/

/

Note: 

1. The residential receptor refers

to an off-facility receptor.

2. No current active construction

at the facility.

3. Precipitation/run-off flows

through the facility's stormwater 

system and retention ponds before 

discharging to Onion Creek, a 

tributary of the Colorado River.

/

Precipitation/ 

Run-Off / /

/

7-8
Media

SOURCE PATHWAY RECEPTOR

AOI 3

AFFF Release 

during testing and 

accidental triggering 

of the AFFF fire 

suppression 

systems. 

Surface Soil 

Subsurface 

Soil via 

infiltration at 

Retention 

Ponds

Human 

Activities

Leaching/ 

Infiltration

Airborne Soil 

particulate

Surface Soil 

at AOI

Surface 

Water/ 

sediment3 Subsurface 

Soil

Shallow 

Groundwater

Source Release 

Mechanism Media Transport and Migration Media Exposure Routes

Inhalation of 

Dust

Ingestion

Ingestion

Ingestion

Ingestion

Human Receptors: 

Current/ Future

Flow-Chart Continues

Partial / Possible Flow

Flow-Chart Stops

Incomplete Pathway

Potentially Complete Pathway

Potentially Complete Pathway 

with Exceedance of SL

Site Worker Construction Worker2 Resident1 Trespasser/ Recreational User

Site Worker Construction Worker2 Resident1 Trespasser/ Recreational User

/

/

LEGEND

/ /

/ / /

Figure 7-3

Conceptual Site Model

AOI 3 Fixed Wing Support Hangar and Storage Hangar

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

/

/

/

/

/

/ /

/

/

Note: 

1. The residential receptor refers

to an off-facility receptor.

2. No current active construction

at the facility.

3. Precipitation/run-off flows

through the facility's stormwater 

system and retention ponds before 

discharging to Onion Creek, a 

tributary of the Colorado River.

/

Precipitation/ 

Run-Off / /

/

7-9
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AECOM 7-10

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AECOM 8-1

8. Summary and Outcome

This section summarizes SI activities and findings. The most significant findings are summarized 

in this section and are reproduced directly or abstracted from information contained in this report. 

The outcome provides general and comparative interpretations of the findings relative to the SLs. 

8.1 SI Activities

The SI field activities were conducted from 7 to 10 June 2021 and consisted of utility clearance, 

direct push boring, soil sample collection, temporary monitoring well installation, grab groundwater 

sample collection, and land surveying. Field activities were conducted in accordance with the SI 

QAPP Addendum (AECOM, 2021a), except as noted in Section 5.8. 

To fulfill the project DQOs set forth in the approved SI QAPP Addendum (AECOM, 2021a), samples 

were collected and analyzed for a subset of 18 compounds by LC/MS/MS compliant with QSM 5.3 

Table B-15 as follows.

• Twenty-seven (27) soil samples from 15 boring locations;

• Six grab groundwater samples from six temporary well locations;

• Fifteen (15) QA/QC samples.

An SI is conducted when the PA determines an AOI exists based on probable use, storage, and/or 

disposal of PFAS-containing materials. The SI includes multi-media sampling at AOIs to 

determine whether or not a release has occurred. The SI may conclude further investigation is 

warranted, a removal action is required to address immediate threats, or no further action is 

required. Additionally, the CSMs were refined to assess whether a potentially complete pathway 

exists between the source and potential receptors for potential exposure at the AOIs, which are 

described in Section 7. 

8.2 Outcome 

Based on the results of this SI, further evaluation is warranted in an RI for each of the four AOIs. 

Based on the CSMs developed and revised in light of the SI findings, there is potential for 

exposure to drinking water receptors from AOI 1 through AOI 4 from sources on the facility

resulting from historical DoD activities. Sample analytical concentrations collected during the SI 

were compared against the project SLs in soil and groundwater, as described in Table 6-1. A 

summary of the results of the SI data relative to the SLs is as follows:

• At AOI 1:

• PFOA, PFOS, PFHxS, and PFNA in groundwater exceeded their respective SLs at

location AOI01-01. PFOA exceed the SL of 6 ng/L, with a maximum concentration of

44.8 J+ ng/L. PFOS exceed the SL of 4 ng/L, with a maximum concentration of 578

ng/L. PFHxS exceed the SL of 39 ng/L, with a maximum concentration of 240 J+

ng/L. PFNA exceeded the SL of 6 ng/L, with a maximum concentration of 9.30 J+

ng/L. Based on the results of the SI, further evaluation of AOI 1 is warranted in the

RI.

• Additionally, PFOA, PFOS, and PFHxS in groundwater exceeded their respective

SLs at facility boundary locations upgradient and downgradient of AOI 1. PFOA

exceeded the SL of 6 ng/L, with a maximum concentration of 24.8 ng/L at location

ABF-02. PFOS exceeded the SL of 4 ng/L, with a maximum concentration of 273
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Austin Bergstrom Army Aviation Support Facility, Austin, Texas

AECOM 8-2

ng/L at location ABF-02. PFHxS exceeded the SL of 39 ng/L, with a maximum 

concentration of 176 at location ABF-02. 

• The detected concentrations of PFOA, PFOS, PFHxS, PFNA, and PFBS in soil at

AOI 1, as well as facility boundary locations upgradient and downgradient of AOI 1,

were below their respective SLs.

• At AOI 2:

• PFOA, PFOS, and PFNA in groundwater exceeded their respective SLs

downgradient of AOI 2 at facility boundary location ABF-05. PFOA exceed the SL of

6 ng/L, with a concentration of 11.9 ng/L. PFOS exceed the SL of 4 ng/L, with a

concentration of 591 ng/L. PFNA exceeded the SL of 6 ng/L, with a concentration of

6.16 ng/L. Based on the results of the SI, further evaluation of AOI 2 is warranted in

the RI.

• The detected concentrations of PFOA, PFOS, PFHxS, and PFNA in soil at AOI 2

were below their respective SLs.

• The detected concentrations of PFOS, PFHxS, and PFBS in soil at facility boundary

location ABF-05, downgradient of AOI 2, were below their respective SLs.

• At AOI 3:

• PFOA and PFOS in groundwater exceeded their respective SLs downgradient of AOI

3 at facility boundary location ABF-04. PFOA exceed the SL of 6 ng/L, with a

concentration of 7.53 ng/L. PFOS exceed the SL of 4 ng/L, with a concentration of

130 ng/L. Based on the results of the SI, further evaluation of AOI 3 is warranted in

the RI.

• The detected concentrations of PFOA, PFOS, and PFNA in soil at AOI 3 were below

their respective SLs.

• The detected concentrations of PFOA, PFOS, PFHxS, PFNA, and PFBS in soil at

facility boundary location ABF-04, downgradient of AOI 3, were below their respective

SLs.

• At AOI 4:

• PFOA, PFOS, and PFHxS in groundwater exceeded their respective SLs at facility

boundary locations upgradient (ABF-01) and downgradient (ABF-02, ABF-03) of AOI

4. PFOA exceed the SL of 6 ng/L, with a maximum concentration of 24.8 ng/L at

location ABF-02. PFOS exceeded the SL of 4 ng/L, with a maximum concentration

of 273 ng/L at ABF-02. PFHxS exceed the SL of 39 ng/L, with a maximum

concentration of 176 ng/L at location ABF-02. Based on the results of the SI, further

evaluation of AOI 4 is warranted in an RI.

• The detected concentrations of PFOA, PFOS, PFHxS, PFNA, and PFBS in soil at

AOI 4, as well as facility boundary locations upgradient and downgradient of AOI 4,

were below their respective SLs.

Of the six PFAS compounds presented in the 6 July 2022 OSD memorandum, HFPO-DA 

(commonly referred to as GenX) was not included as an analyte at the time of this SI. Based on 

the CSM developed during the PA and revised based on SI findings, the presence of HFPO-DA 

is not anticipated at the facility because HFPO-DA is generally not a component of MIL-SPEC 

AFFF and based on its history including distribution limitations that restricted use of GenX, it is 
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Austin Bergstrom Army Aviation Support Facility, Austin, Texas

AECOM 8-3

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

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

Table 8-1 summarizes the SI results for soil and groundwater used to determine if an AOI should 

be considered for further investigation under CERCLA and undergo an RI. 

Table 8-1: Summary of Site Inspection Findings and Recommendations

AOI Potential 

Release Area

Soil –

Source Area

Groundwater –

Source Area

Groundwater –

Facility Boundary Future Action

1 Maintenance 

Hangar Proceed to RI 

2 Wash Rack Proceed to RI

3 

Fixed Wing Support 

Hangar Proceed to RI

Storage Hangar Proceed to RI

4 

Hazardous 

Materials Storage 

Building

Proceed to RI

Fuel Station Proceed to RI

Legend:

= detected; exceedance of the screening levels

= detected; no exceedance of the screening levels

= not detected
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AECOM 8-4

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AECOM 9-1

9. References

ABIA. 2019. Site Topography and Storm Water Drainage System, Figure 4-2. February.

AECOM. 2018a. Final Site Inspection Programmatic Uniform Federal Policy-Quality Assurance 

Project Plan, Perfluorooctane Sulfonic Acid (PFOS) and Perfluorooctanoic Acid (PFOA) 

Impacted Sites ARNG Installations, Nationwide Contract No. W912DR-12-D-0014/

W912DR17F0192. 9 March.

AECOM. 2018b. Final Programmatic Accident Prevention Plan, Perfluorooctane Sulfonic Acid 

(PFOS) and Perfluorooctanoic Acid (PFOA) Impacted Sites ARNG Installations, Nationwide 

Contract No. W912DR-12-D-0014/W912DR17F0192. July.

AECOM. 2020. Final Preliminary Assessment Report, Austin Bergstrom Army Aviation Support 

Facility, Austin, Texas. July. 

AECOM. 2021a. Final Site Inspection Uniform Federal Policy-Quality Assurance Project Plan 

Addendum, Austin Bergstrom Army Aviation Support Facility, Austin, Texas, Perfluorooctane 

Sulfonic Acid (PFOS) and Perfluorooctanoic Acid (PFOA) Impacted Sites ARNG Installations, 

Nationwide. April.

AECOM. 2021b. Final Site Safety and Health Plan, Austin Bergstrom Army Aviation Support 

Facility, Perfluorooctane Sulfonic Acid (PFOS) and Perfluorooctanoic Acid (PFOA) Impacted 

Sites ARNG Installations, Nationwide. June.

Amec Foster Wheeler. 2016. Final Perfluorinated Compound Preliminary Assessment, Former 

Bergstrom AFB, TX. AR #469412. Prepared for Air Force Civil Engineer Center. December. 

Amec Foster Wheeler. 2016. Final Site Investigation Report, Former Bergstrom AFB, TX. Site 

Investigation of Potential Perfluorinated Compound (PFC) Release Areas at Multiple United 

States Air Force Base Realignment and Closure Installations. AR #558322. Prepared for Air 

Force Civil Engineer Center. June.

Assistant Secretary of Defense. 2022. Investigation Per- and Polyfluoroalkyl Substances within 

the Department of Defense Cleanup Program. United States Department of Defense. 

6 July. 

Barker, R.A., and Ardis, A.F. 1996. Hydrogeologic Framework of the Edwards-Trinity Aquifer 

System, West-Central Texas. U.S. Geological Survey Professional Paper 1421-B. 61 p.

DA. 2018. Army Guidance for Addressing Releases of Per- and Polyfluoroalkyl Substances.

4 September.

DoD. 2019a. Department of Defense (DoD), Department of Energy (DOE) Consolidated Quality 

Systems Manual (QSM) for Environmental Laboratories, Version 5.3. 

DoD. 2019b. General Data Validation Guidelines. Environmental Data Quality Workgroup. 

4 November.

Environmental Data Resources, Inc.TM. 2019. The EDR Radius MapTM Report with GeoCheck. 

Austin-Bergstrom AASF. Inquiry Number: 5900192.2s. December.

EA Engineering, Science, and Technology, Inc. 2021. Standard Operating Procedure No. 042A 

for Treating Liquid Investigation-Derived Material (Purge water, drilling water, and 

decontamination fluids). Revision 1. March.
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Austin Bergstrom Army Aviation Support Facility, Austin, Texas

AECOM 9-2

Garner, L.E., and Young, K.P. 1976. Environmental Geology of the Austin Area. University of 

Texas at Austin, Bureau of Economic Geology: Report of Investigations RI-86.

Guelfo, J.L. and Higgins, C.P. 2013. Subsurface Transport Potential of Perfluoroalkyl Acids at 

Aqueous Film-Forming Foam (AFFF)-Impacted Sites. Environmental Science and Technology 

47(9): 4164-71.

Higgins, C.P., and Luthy, R.G. 2006. Sorption of Perfluorinated Surfactants on 

Sediments. Environmental Science and Technology 40 (23): 7251-7256.

ITRC. 2018. Environmental Fate and Transport for Per- and Polyfluoroalkyl Substances. March. 

Jose I. Guerra, Inc. 2010. 24” and 30” Reinforced Concrete Pipe (RCP) Discharge Outlet Plans. 

Engineering Drawings.

Law Environmental, Inc. 1995. Installation Restoration Program (IRP) RCRA Facility 

Assessment/RCRA Facility Investigation, Ground-water Gradient Determination, Bergstrom 

Air Force Base, Austin, Texas. October.

National Oceanic and Atmospheric Administration. 2022. Austin Climate Summary. 

https://www.weather.gov/media/ewx/climate/ClimateSummary-ewx-Austin.pdf. Accessed 18 

August 2022. 

National Weather Service Forecast Office. 2022. Austin/San Antonio, TX. 

https://w2.weather.gov/climate/index.php?wfo=ewx. Accessed 18 August 2022. 

Texas Bureau of Economic Geology. 1981. Geologic Atlas of Texas, Austin Sheet. Scale 

1:250,000.

Texas Water Development Board. 2011. Aquifers of Texas. July. 

http://www.twdb.texas.gov/publications/reports/numbered_reports/doc/R380_AquifersofTexa

s.pdf?d=931170.1400000001. Accessed 21 October 2019.

USACE. 2016. Technical Project Planning Process, EM-200-1-2. 26 February.

USEPA. 1980. Comprehensive Environmental Response, Compensation, and Liability Act 

(CERCLA). 

USEPA. 1994. National Oil and Hazardous Substances Pollution Contingency Plan (Final Rule). 

40 CFR Part 300; 59 Federal Register 47384. September.

USEPA. 2001. Risk Assessment Guidance for Superfund, Volume I: Human Health Evaluation 

Manual (Part D, Standardized Planning, Reporting, and Review of Superfund Risk 

Assessments). December.

USEPA. 2017. National Functional Guidelines for Organic Superfund Data Review. OLEM 

9355.0-136, EPA-540-R-2017-002. Office of Superfund Remediation and Technology 

Innovation. January.

USFWS. 2022. Species by County Report, County: Travis, Texas. Environmental Conservation 

Online System. Accessed 16 August 2022 at https://ecos.fws.gov/ecp/report/species-listingsby-current-range-county?fips=48453. 

USGS. 1993. Quaternary Geologic Map of the Austin 4° x 6° Quadrangle, United States. 

Miscellaneous Investigation Series Map I-1420 (NH-14).
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Xiao, F., Simcik, M. F., Halbach, T. R., and Gulliver, J. S. 2015., Perfluorooctane Sulfonate (PFOS) 

and Perfluorooctanoate (PFOA) in Soils and Groundwater of a U.S. Metropolitan Area: 

Migration and Implications for Human Exposure. Water Research 72: 64-74. 

Young, K. 1977. Guidebook to the Geology of Travis County. Walter Geology Library.
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