FINAL

Site Inspection Report 

Army Aviation Support Facility #2

Birmingham, Alabama

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 

August 2023 

Prepared for:

Army National Guard Bureau

111 S. George Mason Drive

Arlington, VA 22204

UNCLASSIFIED
 

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Army Aviation Support Facility #2, Birmingham, Alabama

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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..............................................................................................2-2

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

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

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

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

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

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

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

3.2 AOI 2 Flight Ramp.................................................................................................3-1

3.3 Adjacent Sources ..................................................................................................3-2

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

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

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

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

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

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

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

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

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

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

6.4 AOI 2.....................................................................................................................6-3
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Army Aviation Support Facility #2, Birmingham, Alabama

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

6.4.2 AOI 2 Groundwater Analytical Results.........................................................6-3

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

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

7.2 Groundwater Exposure Pathway...........................................................................7-2

7.2.1 AOI 1...........................................................................................................7-2

7.2.2 AOI 2...........................................................................................................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

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. Field Change Request Forms

B4. Nonconformance and Corrective Action Reports

B5. Survey Data

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, February, 2022

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

Figure 7-2 Conceptual Site Model, AOI 2

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 Deep Subsurface Soil

Table 6-5 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

°C degrees Celsius

°F degrees Fahrenheit

μg/kg micrograms per kilogram

AASF Army Aviation Support Facility

AECOM AECOM Technical Services, Inc.

AFFF aqueous film-forming foam

ALARNG Alabama Army National Guard

ANG Air National Guard

ANGB Air National Guard Base

amsl above mean sea level

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

DO dissolved oxygen

DOT 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

gpm gallons per minute

GPRS Ground Penetrating Radar Systems

HDPE high-density polyethylene 

HFPO-DA hexafluoropropylene oxide dimer acid

IDW investigation-derived waste

ITRC Interstate Technology Regulatory Council

LC/MS/MS liquid chromatography with tandem mass spectrometry

MIL-SPEC military specification

MS/MSD matrix spike/matrix spike duplicate

NELAP National Environmental Laboratory Accreditation Program

ng/L nanograms per liter

ORP oxidation-reduction potential

OSD Office of the Secretary of Defense

OWS oil-water separator

PA Preliminary Assessment

PFAS per- and polyfluoroalkyl substances
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Army Aviation Support Facility #2, Birmingham, Alabama

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PFBS perfluorobutanesulfonic acid

PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

PID photoionization detector

PQAPP Programmatic UFP-QAPP

PVC polyvinyl chloride

QA quality assurance 

QAPP Quality Assurance Project Plan

QC quality control

QSM Quality Systems Manual

SI Site Inspection

SL screening level

SOP standard operating procedure

TOC total organic carbon

TPP Technical Project Planning

UFP Uniform Federal Policy

US United States

USACE United States Army Corps of Engineers

USCS Unified Soil Classification System

USEPA United States Environmental Protection Agency

USFWS United States Fish and Wildlife Service

WWTP wastewater treatment plant
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Army Aviation Support Facility #2, Birmingham, Alabama

AECOM ES-1

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 

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 two 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 SLs for relevant 

compounds. This SI was completed at the Birmingham Army Aviation Support Facility (AASF) #2 

in Birmingham, Alabama and determined further investigation is warranted for AOI 1: Hangar and 

AOI 2: Flight Ramp. The Birmingham AASF #2 will also be referred to as the “facility” throughout 

this document. 

AASF #2 is located at 5701 E Lake Boulevard, approximately 5 miles northeast of downtown

Birmingham, in Jefferson County, Alabama. The facility is in the northernmost section of the 

Birmingham-Shuttlesworth International Airport, situated on a parcel of land owned by the 

Birmingham Airport Authority (Jefferson County Alabama, 2019). The land is leased from the 

airport authority by the Alabama Air National Guard, who in turn licenses it for use by the Alabama 

Army National Guard (ALARNG). Construction of the facility began around 1965. Based on aerial 

imagery, the hangar building was constructed between 1970 and 1977 and was later expanded 

around 1998. Since its construction, the approximately 22-acre AASF facility has been used by 

ALARNG for the operation, maintenance, and repair of rotary-winged aircraft, and facility buildings 

include one hangar, administrative offices, and classrooms. Water and electric utilities are 

provided by the City of Birmingham. 

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

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 AOI 1: Hangar and AOI 2: Flight Ramp. 

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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Army Aviation Support Facility #2, Birmingham, Alabama

AECOM ES-2

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 Hangar N/A Proceed to RI 

2 Flight Ramp Proceed to RI

Legend:

N/A = not applicable 

= detected; exceedance of the screening levels

= detected; no exceedance of the screening levels

= not detected

1 
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Army Aviation Support Facility #2, Birmingham, Alabama

AECOM 1-1

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 Birmingham Army 

Aviation Support Facility (AASF) #2 in Birmingham, Alabama. The Birmingham AASF #2 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 Birmingham AASF #2 (AECOM Technical Services, Inc. [AECOM], 2020) 

that identified twoAreas 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

AASF #2 is located at 5701 E Lake Boulevard, Birmingham, Jefferson County, Alabama, 

approximately 5 miles northeast of downtown Birmingham. The roughly 22-acre facility is within 

the property of Birmingham-Shuttlesworth International Airport, at the northernmost portion of the 

airport property, just south of E Lake Boulevard. The land is leased from the airport authority by 

the Alabama Air National Guard (ANG), who in turn licenses it for use by the Alabama Army 

National Guard (ALARNG). The latitude and longitude for the approximate center of the AASF are 

33°34’15.35” N; 86°45’0.97” W. Construction of AASF #2 began around 1965. Based on aerial 

imagery, the hangar building was constructed between 1970 and 1977 and was later expanded 

around 1998. The site location is depicted on Figure 2-1. 

Since its construction, AASF #2 is used by ALARNG for the operation, maintenance, and repair 

of rotary-winged aircraft. The facility is covered almost entirely by paved or developed surfaces, 

except for some grassy areas south and east of the flight ramp, and a drainage basin between 

the northeast corner of the AASF and adjacent Birmingham Airport runway. The facility is 

contiguous with the Birmingham Airport to the south and east, as well as an ANG Base (ANGB) 

to the west-northwest, and it is connected to these adjacent facilities via its flight ramp and 

taxiways. Additional ALARNG facilities are located to the north of AASF #2.

2.2 Facility Environmental Setting

AASF #2 is situated in the Valley and Ridge Physiographic Province, which is characterized by a 

series of northeast-trending linear ridges and valleys underlain by alternating beds of hard and 

soft, highly faulted and folded, sedimentary rocks ranging from Cambrian to Pennsylvanian in age 

(Johnson et al., 2002). AASF #2 sits at an elevation of around 630 feet above mean sea level. 

Topography at the facility is relatively flat and slopes gently southward, towards the airport runway. 

Hills rise above the facility towards the north and west (Figure 2-2).

AASF #2 is immediately surrounded on all sides by the Birmingham Airport, the ANGB, and other 

ALARNG facilities. The nearest residential areas are located northwest and southeast of the 

facility, beyond these adjacent facilities. Other commercial and industrial use properties are 

located in the vicinity of the airport. 

2.2.1 Geology

Surface soils in the valleys of the Valley and Ridge Province were formed mainly in residuum of 

weathered limestone and are predominantly red, iron-rich clays with silt loam surface textures. 

The ridges consist of cherty limestone that produce a gravelly loam, gravelly clay subsoil, and a 

gravelly silt loam surface layer. The Bodine and Fullerton soil series cover an extensive part of 

the Valley and Ridge Province (Johnson et al., 2002).

The facility is underlain by the Ketona Dolomite and is located on the Airport anticline, close to 

the contact with the Ordovician and Upper Cambrian Knox Group (Figure 2-3). The Ketona 

Dolomite is characterized as a light to medium gray, thick-bedded, fine- to coarse-grained 

dolomite. The Ketona Dolomite is underlain by the Middle to Upper Cambrian-aged Conasauga 

Formation. The Conasauga Formation comprises three intervals of calcium carbonate rock. The 

uppermost interval is dolomitic, the middle interval is bioclastic and oolitic limestone, and the 

lowest interval is interbedded shale and micritic limestone. The adjacent Knox Group is generally 

described as a light to medium gray, laminated, finely crystalline, cherty dolomite and limestone 

(Rindsberg et al., 2003; Irvin et al., 2006). 
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Army Aviation Support Facility #2, Birmingham, Alabama

AECOM 2-2

Soil borings generally encountered lean clay with varying percentages of sand. Additionally, 

isolated layers of silt and well-graded sand were observed in AOI02-04 and AOI01-02, 

respectively. A reddish brown or reddish yellow lean clay layer was consistently observed in every 

boring, at depths beginning between 13 feet bgs and 19 feet bgs. The aforementioned clay layers 

range in thickness between 8 feet to 11 feet. These observations are consistent with the Bodine 

and Fullerton soil series, which generally produces red, clayey soils through weathering of 

limestone. Direct-push technology (DPT) refusal was encountered at each boring except AOI01-

02, and bedrock was encountered at 33 feet below ground surface (bgs) at boring BHM-01. Boring

depths ranged from 17 to 38 feet bgs, with refusal depth increasing in the northwest direction. 

Based on bedrock observation and refusal depth, depth to bedrock is assumed to increase in the 

northwest direction. This observation is consistent with the known anticline hinge zone to the 

south of the facility, where depth to bedrock is expected to be the shallowest. Bedrock 

compositions were observed to be pulverized carbonate rock and are consistent with the 

descriptions of the Ketona Dolomite.

Boring logs are presented in Appendix E. Samples for grain size analyses were collected at two 

locations, AOI01-02 and AOI02-01, where finer grain materials were observed and were analyzed 

via American Society for Testing and Materials (ASTM) Method D-422. The results for both 

samples were similar and indicate that the soil sample is mostly silt (around 58 percent [%]) and 

clay (38%). The grain size results are presented in Appendix F. 

2.2.2 Hydrogeology

The facility sits atop the Valley and Ridge aquifer system, which includes the Knox Group and

Ketona Dolomite, the two formations present in the immediate vicinity of the AASF (KopaskaMerkel et al., 2005). Generally, the Knox Group ranges in thickness from 1,500 to 3,500 feet and 

produces large quantities of water, with wells yielding up to 800 gallons per minute (gpm). The 

Ketona Dolomite ranges in thickness from 0 to 760 feet and is a major producer of groundwater 

in Jefferson County, with wells yielding around 300 gpm. Groundwater in these units is typically 

found in dissolution channels, where circulating water has dissolved the rock and thus increased 

the secondary porosity (Hunter and Moser, 1990; Kopaska-Merkel et al., 2005).

Shallow groundwater in the vicinity of AASF #2 was anticipated within the unconsolidated 

overburden based on a previous investigation at the adjacent Birmingham ANGB. During that

investigation, saturated soil was observed at shallow depths of less than 20 feet bgs and generally 

did not yield significant quantities of water. Depths to water measured during the Birmingham 

ANGB SI ranged from 4.57 to 11.75 feet bgs (Leidos, 2019). 

Depths to water measured in February 2022 during the AASF #2 SI ranged from 15.49 to 22.91

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

groundwater flow direction is generally to the south. Regional groundwater flow is towards the 

west, according to Valley and Ridge aquifer system potentiometric contour maps (KopaskaMerkel, 2005) (Figure 2-3). 

Drinking water at the facility and surrounding area is supplied by Birmingham Water Works, which

sources its water from the Cahaba River and Lake Purdy, which are 6 and 9 miles southeast of 

the facility, respectively. Based on the research done as part of the PA, only inactive US Geological 

Survey monitoring wells were identified within a 4-mile radius of the facility (AECOM, 2020).

However, a recent review of well records on the Geological Survey of Alabama Groundwater 

Assessment Program’s Water Well Finder identified the nearest wells being just over 3 miles 

southeast of the facility. Based on available information, the wells are constructed within bedrock 

greater than 300 feet deep and designated as industrial or public use (GSA, 2022).
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Army Aviation Support Facility #2, Birmingham, Alabama

AECOM 2-3

2.2.3 Hydrology 

AASF #2 lies within the Mobile River Basin (Johnson et al., 2002) in the Upper Village Creek 

Watershed. The only surface water body near the facility is a retention pond located across the 

airport runway, less than 0.5 miles northeast, but considered hydrologically sperate from the 

facility, and Village Creek, which flows southeast to southwest of AASF #2 and flows into Bayview 

Lake, which is located approximately 11 miles west of the facility. Village Creek and Bayview Lake 

are used for recreational purposes. Surface water features surrounding the facility are shown in 

Figure 2-5. 

Local storm water runoff north of the Hangar flows southwest along the AASF #2 boundary. Storm 

water runoff on the Flight Ramp primarily flows across paved surfaces to the southeast. Storm 

water runoff that is not captured by the sanitary system (i.e. building trench drains and wash rack) 

would infiltrate into unpaved areas or flow into nearby storm drains, such as in the drainage basin 

between the northeast corner of the facility and the adjacent Airport runway. Storm water captured 

at AASF#2 is inferred to join with the larger Airport storm water system and drain to the southwest, 

towards Village Creek.

2.2.4 Climate 

The climate of the Mobile River Basin is warm and humid, ranging from subtropical at the coast 

to temperate at higher elevations. In the summer, the Gulf of Mexico produces warm, humid air 

that moves inland, creating precipitation (Johnson et al., 2002). The average temperature at 

Birmingham is 63.3 degrees Fahrenheit (°F), with an average high of 73.8 °F and an average low 

of 52.8 °F. Birmingham receives an average of 53.71 inches of rain per year (World Climate, 

2020). 

2.2.5 Current and Future Land Use

The Birmingham AASF #2 is a restricted access facility located on the property of BirminghamShuttlesworth International Airport. The facility is surrounded by the Airport to the south and east 

and Birmingham ANGB to the west-northwest. Additional ALARNG facilities are located to the 

north. Residential areas exist to the northwest and southeast, beyond the Airport and ANGB. 

Reasonably anticipated future land use is not expected to change from the current land use.

2.2.6 Sensitive Habitat and Threatened/ Endangered Species 

A wildlife survey has not occurred at the facility, and the facility does not have any significant areas 

of habitat. The following species have not been identified at the facility but may be present in the 

surrounding area. 

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

proposed, and/ or are listed as candidate species in Jefferson County, Alabama (US Fish and 

Wildlife Service [USFWS], 2022. 

• Insects: Monarch butterfly, Danaus plexippus (candidate)

• Mammals: Gray Bat, Myotis grisescens (endangered), Indiana Bat, Myotis sodalis

(endangered), Northern long-eared bat, Myotis septentrionalis (threatened)

• Flowering plants: Gentian pinkroot, Spigelia gentianoides (endangered), tennessee

yellow-eyed-grass, Xyris tennesseensis (endangered), Georgia rockcress, Arabis

georgiana (threatened), White fringeless orchid, Platanthera integrilabia (threatened),
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Mohr’s Barbara’s buttons, Marshallia mohrii (threatened), Small whorled pogonia, Isotria 

medeoloides (threatened)

• Reptiles: Flattened must turtle, Sternotherus depressus, (threatened)

2.3 History of PFAS Use

Two AOIs were identified in the PA where AFFF may have been used, stored, disposed, or 

released historically at AASF #2 (AECOM, 2020). PFAS-containing materials were potentially 

released to surface soil within the boundary of AASF #2 through equipment discharge, accidental 

leaks and spills, and any potential undocumented fire suppression system testing. 

The Hangar is equipped with a fire suppression system that utilizes AFFF. Although there are no 

documented releases from the system, AFFF may have been released during system 

maintenance or accidental leaks and spills, as supported by information provided by ALARNG 

during SI report preparation that noted a 2010 release of AFFF along the northwest side of the 

Hangar. The Hangar floor and trench drains convey to the oil-water separator (OWS) located just 

east of the building. AFFF releases may also have occurred from incidental spills on the Flight 

Ramp, where ARNG staged mobile fire extinguishers until 2010. Information obtained during SI 

planning indicated that nozzle testing may have been performed by the ANGB fire department at 

AASF #2, on the paved area just southwest of the Flight Ramp. A description of each AOI is 

presented in Section 3. 
AASF #2, Birmingham, AL

^_

Legend

Facility Boundary

CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

BM

8/24/2022

8/24/2022

Site Inspection at AASF #2, Birmingham, AL

8/24/2022 ­ Figure 2-1 PM CM 8/24/2022

12420 Milestone Center Drive

Germantown, MD 20876

Facility Location

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

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

1:75,000

0 0.75 1.5 3

Miles

PROJECT

AECOM 2-5
Legend

Facility Boundary

CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

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PMpw - Parkwood Formation

Mb - Bangor Limestone

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Mh - Hartselle Sandstone

Mpm - Pride Mountain Formation

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Dc - Chattanooga Shale

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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, two potential release areas, the 

Hangar and the Flight Ramp, were identified at Birmingham AASF #2 and made into two AOIs 

(AECOM, 2020). The potential release areas are shown on Figure 3-1. 

3.1 AOI 1 Hangar

AOI 1 is located in the north part of the facility and encompasses the Hangar. Eight 55-gallon floor 

tanks containing Ansulite 3 percent (%) AFFF were obtained in 1996 and kept in the Hangar. In 

1998, an overhead fire suppression system equipped with two 1,400-gallon AFFF tanks was 

installed. The AFFF tanks are housed in the mechanical room (Room #115), which is located near 

the east corner of the building. Based on markings, the tanks were likely filled in 1997 and refilled 

in August 1998. In 2010, the fire suppression system was refurbished, and the AFFF was again 

replaced. Information regarding a full-scale test of the suppression system, prior to or after 

refurbishment, could not be ascertained. The PA indicated there were no reported leaks or spills 

of AFFF; however, corrosion on the side of the large tanks was evident. Additionally, information 

provided by ALARNG during SI report preparation noted the apparent release of AFFF around 

2010, likely during replacement of the AFFF in the Hangar fire suppression system. Photographs 

provided by ALARNG suggest that AFFF was released to the ground surface on the service drive 

located immediately beside the northwest exterior wall of the Hangar. AFFF may have also been 

released down drains it the Hangar. 

Releases at AOI 1 would have occurred on the Hangar floor or mechanical room, both of which 

drain to floor and trench drains. These drains would convey any AFFF with wastewater to the 

OWS and then discharge to the sanitary sewer. This discharge includes wastewater captured not 

only by building floor and trench drains, but also the Wash Rack. The Village Creek Wastewater 

Treatment Plant (WWTP) treats wastewater from the facility (Jefferson County Environmental 

Services Department, 2016). AFFF released outside of the Hangar may have infiltrated into the 

subsurface or run off to storm water drains. It is also possible AFFF released may have infiltrated 

into the subsurface soil via joints in the floor slab or could have traveled outside the Hangar and 

onto the flight ramp and surrounding grassy areas. 

3.2 AOI 2 Flight Ramp

AOI 2 encompasses the Flight Ramp located south of the Hangar. Approximately 16 Tri-MaxTM 

30 mobile extinguisher units equipped with AFFF were staged on the Flight Ramp until 2010. No 

information was provided regarding the date the units were obtained or on the disposal of the 

units or AFFF within. There were no records of discharges or spills of AFFF at AOI 2 by ARNG at 

the time of the PA; however, during a November 2021 site visit, facility personnel noted that fire 

response personnel from the adjacent ANBG had occasionally performed nozzle testing on the 

paved area contiguous with the southwest side of the Flight Ramp, on AASF #2. The PA did not 

originally consider this location a potential release area because ALARNG personnel stated the 

Flight Ramp was only used for safety training, but it has been added to AOI 2 for this SI. 

Any releases at AOI 2 would have occurred on both pavement and grassy surfaces. The 

pavement drains via trench drains along the southern edge of the Flight Ramp to the storm water

sewer. AFFF may have infiltrated into the subsurface soil via cracks or joints in the pavement or, 

where trench drains are not present, to the surrounding grassy areas.
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3.3 Adjacent Sources

Two potential off-facility sources of PFAS adjacent to AASF #2, not under the control of the 

ALARNG, were identified during the PA. These potential off-facility sources include the 

Birmingham ANGB and the Birmingham-Shuttlesworth International Airport. The Birmingham 

ANGB, which licenses use of the AASF property to ALARNG, is located immediately southwest 

of AASF #2. An SI for PFOS and PFOA was performed at the Birmingham ANGB in February 

2019 during which six potential release areas were investigated based on the historical presence 

of AFFF at the site. Results indicated PFOA and PFOS were detected in groundwater at a 

combined maximum concentration of 45,230 nanograms per liter (ng/L). Both compounds were 

also detected in soil (Leidos, 2019). 

Birmingham-Shuttlesworth International Airport is located directly adjacent to AASF #2, with its 

property extending east, south, and west of the facility. A PA report completed for the Birmingham 

ANGB identified four potential source areas on the airport property (BB&E, 2016). These areas 

were not addressed in the ANGB SI, as they are not on ANGB property. These potential adjacent 

sources are also shown on Figure 3-1; however, it must be noted that this SI did not evaluate offfacility sources, and these locations are shown for informational purposes only.
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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, 2021), the objective of the SI is to identify 

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

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

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

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

AOIs.

4.1 Problem Statement

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

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

are presented in Section 6.1 of this report. 

4.2 Information Inputs

Primary information inputs included:

• The PA for AASF #2 Birmingham (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, 2021); 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). The SI scope was bounded vertically by the observed depths of the surficial groundwater 

table or drilling refusal, where encountered. Temporal boundaries were limited by seasonal conditions 

present during the Winter 2022 field work. 

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, 2021). 

4.5 Data Usability Assessment

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

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

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

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

installation-specific DQOs. Both sampling and analytical activities are considered to assess 
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AECOM 4-2

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, 2021). 

 
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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 Preliminary Assessment Report, Birmingham Army Aviation Support Facility #2,

Alabama dated September 2020 (AECOM, 2020);

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

dated March 2018 (AECOM, 2018a);

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

Army Aviation Support Facility #2, Birmingham, Alabama dated September 2021 (AECOM,

2021);

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

• Final Site Safety and Health Plan, Army Aviation Support Facility #2, Birmingham, Alabama

dated February 2022 (AECOM, 2022).

The SI field activities were conducted from 14 to 17 February 2022 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, 2021), 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-seven (27) soil samples from twelve (12) boring locations;

• Six (6) grab groundwater samples from seven (7) 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, Field Change Request forms are 

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

Appendix B4, and land survey data are provided in Appendix B5. Additionally, a photographic 

log of field activities is provided in Appendix C. 

5.1 Pre-Investigation Activities

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

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

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

5.1.1 Technical Project Planning

The 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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Army Aviation Support Facility #2, Birmingham, Alabama

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 22 September 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, ARNG, ALARNG, USACE, and representatives familiar 

with the facility. 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, 2021). 

A TPP Meeting 3 was held on 26 July 2023 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 

Both AECOM and their drilling subcontractor, Walker Hill Environmental, Inc., placed a ticket with 

the Alabama 811 public utility clearance provider to notify them of intrusive work. Additionally, 

AECOM contracted Ground Penetrating Radar Systems (GPRS), a private utility location service, 

to perform utility clearance on the facility. GPRS performed utility clearance of the proposed boring 

locations on 14 February 2022 with input from the AECOM field team and AASF #2 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

Two potable water sources at Birmingham AASF #2 were sampled on 16 November 2021 to 

assess usability for decontamination of drilling equipment. Results of both samples collected 

confirmed the sources to be acceptable for use in this investigation; therefore, the spigot at the 

wash rack (BHM-DECON-01) 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 samples 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, 2021). 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 to avoid disturbing concrete or asphalt surfaces. Soil 

samples were collected via hand auger and DPT, in accordance with the SI QAPP Addendum 

(AECOM, 2021). AGeoProbe® 7822DT 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 

approximately 2 feet above the groundwater table, and one subsurface soil sample at the mid-
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point between the surface and the groundwater table. One multi-interval surface soil sample was 

taken near the OWS northeast of AOI 1, at location AOI01-05, to increase data density around 

the OWS. Two additional surface soil samples, AOI02-05 and AOI02-06, were also added to offer 

better data density at the recently identified potential release area near the paved area southwest 

of AOI 2. The soil sample deviations are discussed further in Section 5.9. 

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 sampling forms (Appendix B2) 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. The boring logs are provided in Appendix E. 

Direct push soil borings were completed during the SI at depths ranging between 17 to 38 feet 

bgs. Soil borings completed during the SI found low to medium plasticity lean clays with varying 

amounts of sand as the dominant lithology of the unconsolidated sediments below AASF #2. 

Isolated layers of well-graded sand and silt were also observed in borings AOI01-02 and AOI02-

04, respectively. A reddish brown or reddish yellow lean clay layer was consistently observed in 

the borings, at depths beginning between 13 feet bgs and 19 feet bgs. The aforementioned clay 

layers range in thickness between 8 feet to 11 feet. These observations are consistent with the 

Bodine and Fullerton soil series, which generally produces red, clayey soils through weathering 

of limestone. Bedrock refusal was encountered at BHM-01, at a depth of 33 feet bgs, and was 

observed to be pulverized carbonate rock, consistent with descriptions of the Ketona Dolomite. 

DPT refusal was encountered at each boring except AOI01-02. These observations are consistent 

with the reported geological setting of the region. 

Each soil sample was collected into laboratory-supplied 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), pH (USEPA Method 9045D), and grain size (ASTM Method D-422) in 

accordance with the SI QAPP Addendum (AECOM, 2021).

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 (°C) during shipment.

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

accordance with the SI QAPP Addendum (AECOM, 2021) using bentonite-cement grout at 

completion of sampling activities.

5.3 Temporary Well Installation and Groundwater Grab Sampling

Temporary wells were installed using a GeoProbe® 7822DT dual-tube sampling system. Once

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

section of 1-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. 
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Sufficient time was allowed for groundwater accumulation in the temporary wells before 

proceeding with collection of groundwater samples. After the recharge period, groundwater 

samples were collected using a peristaltic 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. 

Each sample was collected into laboratory-supplied 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, 2021).

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, 2021) by removing the PVC and backfilling 

the hole with a bentonite-cement grout. 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 on 16 February 2022. Groundwater 

elevation measurements were collected from the 6 new temporary monitoring wells. Water level 

measurements were taken from the northern side of the well casing. Groundwater was measured 

between 15.49 to 22.91 feet bgs. 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 Alabama-licensed land surveyors following 

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

data from the newly installed wells on the facility were collected on 16 February 2022 in the 

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

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

provided in Appendix B5. 

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, 2021) and with the DA Guidance for 

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

Soil IDW (i.e., soil cuttings) were generated during the SI activities from the ten soil boring 

locations. No soil IDW was generated at the surface soil sample locations. Due to the minimal 

amount of soil IDW generated, all soil IDW were containerized in labeled, 55-gallon Department 
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of Transportation (DOT)-approved steel drums and stored on the concrete pad adjacent to the 

wash rack area (just south of boring BHM-01). Based on laboratory results, containerized soil 

cuttings will be managed and disposed of off-facility by ARNG, under a separate contract held by 

EA Engineering, Science, and Technology, Inc. (EA). Specifics on the disposal of solid IDW will 

be addressed in an IDW Treatment Memorandum submitted by EA. 

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

decontamination fluids) were containerized in two labeled, 55-gallon DOT-approved steel drums 

and stored next to the soil IDW drums. Based on laboratory results, ARNG will manage and 

dispose of the liquid IDW off-facility under a separate contract held by EA. Specifics on the 

disposal of liquid IDW will be addressed in an IDW Treatment Memorandum submitted by EA. 

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

Three deviations from the SI QAPP Addendum were identified during review of the field 

documentation. The deviation is noted below and is documented in two Field Change Request 

Forms (Appendix B3) and a Nonconformance and Corrective Action Report (Appendix B4): 

• Shortly after the completion of the SI field activities, it was discovered that the laboratoryprovided bottleware used to collect soil and groundwater samples for the AASF #2

Birmingham PFAS SI had lids containing PTFE (i.e., Teflon) components, a known

potential source of PFAS. The laboratory was instructed to provide rush turnaround of the

sample results, including the SI’s QC blank samples – which were confirmed to have been

collected in containers with PTFE-containing lids – to evaluate data usability and potential

contamination to the samples from the lids. The AECOM team also requested the laboratory

prepare and analyze an additional QC blank sample using the same PTFE-containing

bottles. Laboratory results for all QC blank sample results, both field and laboratory

prepared, were non-detect for all analyzed PFAS compounds, indicating that the PTFEcontaining lids did not leach PFAS concentrations to the samples. Therefore, data

qualification due to the use of the PTFE-containing lids was deemed not to be necessary,

no impact on the data is anticipated, and positive results and estimate detections are

considered true positives. This action was documented in a nonconformance and corrective

action report provided in Appendix B4.

• SI field activities found bedrock refusal at varying depths in all direct-push drilling locations,

consistent with expectations based on information available during the PA and SI QAPP

development. At boring location AOI02-04, the temporary well installed in this borehole did

not produce sufficient groundwater to sample over 48 hours. To offset the loss of a

groundwater sample at AOI02-04, an alternate soil boring and temporary well were

completed at location AOI01-02, originally scoped as a surface soil sample only. The

spacing of the other three AOI 2 groundwater sample locations are considered adequate to

meet the data quality objectives. Further, the additional groundwater sample at AOI 1

provides an extra data point between the AASF hangar and adjacent ANGB. This action

was documented in a field change request form provided in Appendix B3.
Site Inspection Report

Army Aviation Support Facility #2, Birmingham, Alabama

AECOM 5-6

• The PA for AASF #2 Birmingham identified AOI 2 as the Flight Ramp based on the 

historical presence of Tri-Max units; however, the PA found there were no known releases 

of AFFF at AOI 2. Sample location AOI02-03 was identified in the Final SI QAPP to 

characterize soil and groundwater at the southwest corner of AOI 2. During a preliminary 

site walk of the sample locations, ALARNG noted that fire response personnel from the 

adjacent ANG facility have occasionally performed nozzle testing on the paved area just 

southwest of AOI 2, on the AASF facility. This paved area was not included with AOI 2 

previously, since ALARNG noted it was used for safety training only. Due to the possible 

release of AFFF during the recently identified nozzle testing, AOI 2 was expanded to include 

the paved area to the immediate southwest side. Location AOI02-03 met the original data 

quality objectives identified in the SI QAPP. Two additional surface soil samples, AOI02-05 

and AOI02-06, were added along the downslope side of the paved area to offer better data 

density where surface runoff from the paved area occurs. The soil boring locations are 

shown in Figure 5-1. This action was documented in a field change request form provided 

in Appendix B3. 
Table 5-1

Site Inspection Results by Medium

Site Inspection Report, AASF #2 Birmingham, Alabama

Sample Identification

Sample

Collection 

Date

Sample Depth 

(feet bgs)

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

Comments

Soil Samples

AOI01-01-SB-00-02 2/14/2022 0-2 x x x

AOI01-01-SB-00-02-D 2/14/2022 0-2 x Duplicate

AOI01-01-SB-00-02-MS 2/14/2022 0-2 x MS/MSD

AOI01-01-SB-00-02-MSD 2/14/2022 0-2 x MS/MSD

AOI01-01-SB-10-12 2/15/2022 10-12 x

AOI01-01-SB-22-24 2/15/2022 22-24 x

AOI01-02-SB-00-02 2/14/2022 0-2 x

AOI01-02-SB-13-15 2/16/2022 13-15 x

AOI01-02-SB-30-32 2/16/2022 30-32 x x

AOI01-03-SB-00-02 2/14/2022 0-2 x

AOI01-03-SB-00-02-D 2/14/2022 0-2 x Duplicate

AOI01-04-SB-00-02 2/14/2022 0-2 x

AOI01-05-SB-00-02 2/15/2022 0-2 x

AOI01-05-SB-04-05 2/15/2022 4-5 x

AOI02-01-SB-00-02 2/14/2022 0-2 x

AOI02-01-SB-10-12 2/15/2022 10-12 x

AOI02-01-SB-19-21 2/15/2022 19-21 x x

AOI02-02-SB-00-02 2/14/2022 0-2 x

AOI02-02-SB-13-15 2/14/2022 13-15 x

AOI02-02-SB-28-30 2/14/2022 28-30 x

AOI02-03-SB-00-02 2/14/2022 0-2 x x x

AOI02-03-SB-00-02-D 2/14/2022 0-2 x x Duplicate

AOI02-03-SB-00-02-MS 2/14/2022 0-2 x x MS/MSD

AOI02-03-SB-00-02-MSD 2/14/2022 0-2 x x MS/MSD

AOI02-03-SB-10-12 2/14/2022 10-12 x

AOI02-03-SB-18-20 2/14/2022 18-20 x

AOI02-04-SB-00-02 2/14/2022 0-2 x

AOI02-04-SB-08-10 2/14/2022 8-10 x

AOI02-04-SB-15-16 2/14/2022 15-16 x

AOI02-05-SB-00-02 2/14/2022 0-2 x

AOI02-05-SB-00-02-MS 2/14/2022 0-2 x MS/MSD

AOI02-05-SB-00-02-MSD 2/14/2022 0-2 x MS/MSD

AOI02-06-SB-00-02 2/14/2022 0-2 x

BHM-01-SB-00-02 2/15/2022 0-2 x

BHM-01-SB-00-02-D 2/15/2022 0-2 x Duplicate

BHM-01-SB-13-15 2/15/2022 13-15 x

AECOM 5-7
Table 5-1

Site Inspection Results by Medium

Site Inspection Report, AASF #2 Birmingham, Alabama

BHM-01-SB-28-30 2/15/2022 28-30 x

Groundwater Samples

AOI01-01-GW 2/16/2022 NA x

AOI01-02-GW 2/16/2022 NA x

AOI02-01-GW 2/16/2022 NA x

AOI02-01-GW-D 2/16/2022 NA x Duplicate

AOI02-02-GW 2/15/2022 NA x

AOI02-03-GW 2/15/2022 NA x

AOI02-03-GW-MS 2/15/2022 NA x MS/MSD

AOI02-03-GW-MSD 2/15/2022 NA x MS/MSD

BHM-01-GW 2/16/2022 NA x

Blank Samples

BHM-FRB-01 2/16/2022 NA x FRB

BHM-ERB-01 2/14/2022 NA x ERB

BHM-ERB-02 2/15/2022 NA x ERB

DECON Samples

BHM-DECON-01 11/16/2022 NA x DECON

BHM-DECON-02 11/16/2022 NA x DECON

Notes:

AASF = Army Aviation Support Facility MS/MSD = matrix spike/matrix spike duplicate

AOI = Area of Interest pH = potential for hydrogen

bgs = below ground surface SB = soil boring

D = duplicate SHEL = Shelbyville

ERB - equipment blank TOC = total organic carbon

FRB - field reagent blank USEPA = United States Environmental Protection Agency

MW = monitoring well

AECOM 5-8
Table 5-2

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

Site Inspection Report, AASF #2 Birmingham, Alabama

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)

Dep

Wa

(feet 

AOI01-01 24 19 - 24 644.53 644.40 23.04 22AOI01-02 38 33 - 38 644.97 644.61 15.85 15AOI02-01 23 18 - 23 637.71 637.57 19.2 19AOI02-02 33 28 - 33 637.11 636.91 18.32 18AOI02-03 20 15 - 20 628.87 628.81 17.85 17AOI02-04 17 12 - 17 629.42 629.49 NA N

BHM-01 33 28 - 33 647.89 645.75 18.93 16

Notes:bgs = below ground surfacebtoc = below top of casingNA = not applicableNAVD88 = North American Vertical Datum 1988

AOI 1AOI 2

AECOM 
THIS PAGE INTENTIONALLY BLANK

M 5-10
?!

?!

"S

"S

"S

?!

?!

?!

!?

?!

"S

"S

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI01-05

AOI02-01

AOI02-02

AOI02-03

AOI02-04

BHM-01

AOI02-05

AOI02-06

0 100 200 400

Feet

Legend

?! Soil and Groundwater Sample

!? Soil Sample

"S Surface Soil Sample

"S Multiple Interval Soil Sample

Facility Boundary

Groundwater Flow Direction

CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

MC

2/9/2023 2/9/2023

2/9/2023 ­ Figure 5-1 PM CM 2/9/2023

12420 Milestone Center Drive

Germantown, MD 20876

Site Inspection Sample Locations

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

and the GIS User Community

1:2,400

PROJECT Site Inspection at AASF #2, Birmingham, AL

AECOM 5-11
Site Inspection Report

Army Aviation Support Facility #2, Birmingham, Alabama

AECOM 5-12

THIS PAGE INTENTIONALLY BLANK
Site Inspection Report

Army Aviation Support Facility #2, Birmingham, Alabama

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 6.5. Table 6-2 through Table 6-5 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 to the SLs presented in Table 6-1. The SLs 

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

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

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

and the industrial/commercial worker scenario is applied to shallow subsurface soil results (2 to 

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

feet is the anticipated limit of construction activities.
Site Inspection Report

Army Aviation Support Facility #2, Birmingham, Alabama

AECOM 6-2

6.2 Soil Physicochemical Analyses

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

size, which are important for evaluating transport through the soil medium. Appendix F contains 

the results of the TOC, pH, and grain size 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: Hangar. The soil and groundwater results are summarized on Table 6-2 through Table 6-

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

6.3.1 AOI 1 Soil Analytical Results

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

AOI01-05. Soil was also sampled from shallow subsurface soil (13 to 15 feet bgs) from boring 

locations AOI01-01, AOI01-02, and AOI01-05 and deep subsurface soil (15 to 32 feet bgs) from

boring locations AOI01-01 and AOI01-02. Figure 6-1 through Figure 6-5 present the ranges of 

detections in soil. Table 6-2 through Table 6-4 summarize the soil results. 

PFOA, PFOS, PFBS, PFHxS, and PFNA were detected in surface soil, at concentrations below 

their SLs. PFOS and PFHxS were also detected in shallow subsurface soil below their SLs, and

PFOS, PFBS, and PFHxS were detected in the deep subsurface soil. 

PFOA, PFOS, PFBS, PFHxS, and PFNA were detected in surface soil, at concentrations below

their SLs. PFOA, PFOS, PFHxS, and PFNA were detected at all five locations, and PFBS was 

detected at two of the five locations. The maximum detected concentration among all five 

compounds in surface soil was PFOS, with a concentration of 3.79 micrograms per kilogram 

(μg/kg) at location AOI01-03.

PFOS and PFHxS were detected in shallow subsurface soil, at concentrations below their SLs. 

PFOS was detected at all three locations, and PFHxS was detected at two of the three locations. 

The maximum concentration of these compounds in shallow subsurface soil was PFOS detected 

at0.444 J μg/kg at AOI01-05. PFOA, PFNA, and PFBS were not detected in shallow subsurface 

soil. PFOS, PFBS, and PFHxS were detected in deep subsurface soil at location AOI01-02 at a 

maximum concentration of 0.393 J μg/kg. PFOA and PFNA were not detected in deep subsurface 

soil.

6.3.2 AOI 1 Groundwater Analytical Results 

Groundwater was sampled from temporary monitoring wells AOI01-01 and AOI01-02. Figure 6-6

and Figure 6-7 present the ranges of detections in groundwater. Table 6-5 summarizes the 

groundwater results. 
Site Inspection Report

Army Aviation Support Facility #2, Birmingham, Alabama

AECOM 6-3

PFOA, PFOS, and PFHxS were detected in groundwater above their SLs. PFBS and PFNA were 

detected in groundwater below their SLs.

PFOA exceeded the SL of 6 ng/L at a concentration of 98.4 ng/L at AOI01-02. PFOS exceeded

the SL of 4 ng/L at both locations, at a maximum concentration of 10.6 ng/L at AOI01-01. PFHxS 

exceeded the SL of 39 ng/L, at a concentration of 65.7 ng/L at AOI01-02. PFBS and PFNA were 

detected below their SLs, at maximum concentrations of 17.3 ng/L and 2.57 ng/L, respectively. 

6.3.3 AOI 1 Conclusions

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

concentrations below their SLs. PFOA, PFOS, and PFHxS 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: Flight Ramp. The results in soil and groundwater are summarized on Table 6-2 through 

Table 6-5. Soil and groundwater results are presented on Figure 6-1 through Figure 6-7. 

6.4.1 AOI 2 Soil Analytical Results

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

AOI02-06 and BHM-01. Soil was also sampled from shallow subsurface soil (13 to 15 feet bgs) 

and deep subsurface soil (15 to 32 feet bgs) from boring locations AOI02-01 through AOI02-04

and BHM-01. Figure 6-1 through Figure 6-5 present the ranges of detections in soil. Table 6-2 

through Table 6-4 summarize the soil results. 

PFOS was detected in surface soil above the SL. PFOA, PFBS, PFHxS, and PFNA were detected 

in surface soil, at concentrations below respective SLs. PFOS, PFBS, and PFHxS were detected 

in shallow and deep subsurface below their SLs. 

PFOS was detected in surface soil above the SL of 13 μg/kg at four of the seven locations, with

a maximum concentration of 64.5 J μg/kg at BHM-01. PFOA, PFBS, PFHxS, and PFNA were 

detected at least one order of magnitude below their SLs. The maximum detected concentration 

among these four compounds detected below the SL was PFHxS, which was detected at a 

concentration of 1.68 μg/kg at A0I02-05. 

PFOS, PFHxS, and PFBS were detected in shallow subsurface soil at concentrations at least one 

order of magnitude below their SLs. These compounds were also detected in deep subsurface 

soil. The maximum detected concentration among the three compounds at both intervals was 

PFOS, which was detected at 0.925 J μg/kg at BHM-01 in shallow subsurface soil and at 1.49 

μg/kg at AOI02-04 in deep subsurface soil. PFOAand PFNA were not detected in shallow or deep

subsurface soil.

6.4.2 AOI 2 Groundwater Analytical Results 

Groundwater was sampled from temporary monitoring wells AOI2-01 through AOI2-03 and BHM01. Figure 6-6 and Figure 6-7 present the ranges of detections in groundwater. Table 6-5

summarizes the groundwater results.

PFOA, PFOS, PFHxS and PFNA were detected in groundwater above their respective SLs. PFBS 

was detected in groundwater below the SL. PFOA, PFOS, and PFHxS exceeded their respective 

SLs in groundwater in all four locations. PFNA exceeded the SL at only location AOI02-03, at a 
Site Inspection Report

Army Aviation Support Facility #2, Birmingham, Alabama

AECOM 6-4

concentration of 14.6 ng/L. The maximum concentrations of PFOA, PFOS, and PFHxS were also 

found at AOI02-03, at 73.8 ng/L, 697 ng/L, and 782 ng/L, respectively. PFBS was detected below 

the SL at AOI02-03, at a maximum concentration of 84.7 ng/L.

6.4.3 AOI 2 Conclusions

Based on the results of the SI, PFOS was detected in soil at a concentration above the SL. PFOA, 

PFOS, PFHxS, and PFNA were detected in groundwater at concentrations above their SLs. 

Based on the exceedances of the SLs in soil and groundwater, further evaluation at AOI 2 is 

warranted. 
Table 6-2

PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Surface Soil

Site Inspection Report, AASF #2 Birmingham

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Re

PFBS 1900 ND UJ 0.083 J 0.175 J ND U ND U ND U ND U ND U ND PFHxS 130 0.565 J 1.00 J 0.908 J 0.053 J 0.043 J 0.071 J 0.241 J 0.053 J 0.124 PFNA 19 0.560 J 0.515 J 0.178 J 1.68 2.18 0.286 J 0.055 J 0.057 J ND 

PFOA 19 0.578 J 0.657 J 0.273 J 0.777 J 0.726 J 0.387 J 0.092 J ND U ND PFOS 13 2.88 J- 3.17 J- 3.02 2.87 3.79 0.444 J 1.68 1.44 0.589 

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acidPFOA perfluorooctanoic acidPFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AASF Army Aviation Support FacilityJ- = Estimated concentration, biased low AOI Area of InterestU = The analyte was not detected at a level greater than or equal to the adjusted DL BHM Birmingham

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 feetND = Analyte not detected above the LOD. LOD values are presented in Appendix F. HQ hazard quotient

ID identificationLCMSMS liquid chromatography with tandem LOD limit of detectionND analyte not detected above the LODOSD Office of the Secretary of DefenseQSM Quality Systems ManualQual interpreted qualifierSB soil boringUSEPA United States Environmental Protecμg/kg micrograms per kilogram

Area of Interest

Sample ID

Sample Date

Depth

AOI01-01-SB-00-02

02/14/2022

0-2 ft

AOI01-01-SB-00-02-D

02/14/2022

0-2 ft

AOI01-02-SB-00-02

02/14/2022

0-2 ft

AOI01-05-SB-00-02

02/15/2022

0-2 ft

AOI01-03-SB-00-02

02/14/2022

0-2 ft

AOI01-03-SB-00-02-D

02/14/2022

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.

AOI01 

Soil, LCMSMS compliant with QSM 5.3 Table B-15 (μg/kg)

AOI02-01-SB-00-02

02/14/2022

0-2 ft

AOI

AOI01-04-SB-00-02

02/14/2022

0-2 ft

AECOM 
Table 6-2

PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Surface Soil

Site Inspection Report, AASF #2 Birmingham

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual Result Qual

PFBS 1900 ND U 0.087 J 0.057 J 0.026 J 0.026 JPFHxS 130 0.159 J 1.68 J- 1.42 0.443 J 0.525 JPFNA 19 0.051 J 1.20 J- 0.649 J ND U ND UPFOA 19 0.113 J 1.39 J- 0.784 J ND U ND UPFOS 13 8.35 54.7 J 17.1 64.5 51.8

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acidPFOA perfluorooctanoic acidPFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AASF Army Aviation Support FacilityJ- = Estimated concentration, biased low AOI Area of InterestU = The analyte was not detected at a level greater than or equal to the adjusted DL BHM Birmingham

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 feetND = Analyte not detected above the LOD. LOD values are presented in Appendix F. HQ hazard quotient

ID identificationLCMSMS liquid chromatography with tandem LOD limit of detectionND analyte not detected above the LODOSD Office of the Secretary of DefenseQSM Quality Systems ManualQual interpreted qualifierSB soil boringUSEPA United States Environmental Protecμg/kg micrograms per kilogram

Area of Interest

Sample ID

Sample Date

Depth

AOI02-04-SB-00-02

02/14/2022

0-2 ft

AOI02

Soil, LCMSMS compliant with QSM 5.3 Table B-15 (μg/kg)

a. Assistant Secretary of Defense, July 2022. Risk Based Screening Levels Calculated for PFOA, PFOS, PFBS, PFHxS, and PFNA in Groundwater or Soil using USEPA’s Regional Screening Level Calculator. HQ=0.1, May 2022. Soil screening levels based on residential scenario for incidental ingestion of contaminated soil.

BHM-01-SB-00-02

02/15/2022

0-2 ft

BHM-01-SB-00-02-D

02/15/2022

0-2 ft

AOI02-05-SB-00-02

02/14/2022

0-2 ft

AOI02-06-SB-00-02

02/14/2022

0-2 ft

AECOM 
Table 6-3

PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Shallow Subsurface Soil

Site Inspection Report, AASF #2 Birmingham

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual

PFBS 25000 ND U ND U ND U ND U ND U 0.039 J ND U 0.035 JPFHxS 1600 0.078 J ND U 0.065 J 0.065 J ND U 0.261 J 0.061 J 0.179 JPFNA 250 ND U ND U ND U ND U ND U ND U ND U ND UPFOA 250 ND U ND U ND U ND U ND U ND U ND U ND UPFOS 160 0.249 J+ 0.158 J 0.444 J ND U ND U 0.523 J ND U 0.925 J

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acidPFOA perfluorooctanoic acidPFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AASF Army Aviation Support FacilityJ+ = Estimated concentration, biased high AOI Area of InterestU = The analyte was not detected at a level greater than or equal to the adjusted DL BHM Birmingham

DL detection limit

Notes ft feet

ND = Analyte not detected above the LOD. LOD values are presented in Appendix F. HQ hazard quotient

ID identificationLCMSMS liquid chromatography with tandem LOD limit of detectionND analyte not detected above the LODOSD Office of the Secretary of DefenseQSM Quality Systems ManualQual interpreted qualifierSB soil boringUSEPA United States Environmental Protecμg/kg micrograms per kilogram

Area of Interest AOI02

Sample ID

Sample Date

Depth

AOI01-01-SB-10-12

02/15/2022

10-12 ft 10-12 ft

AOI02-02-SB-13-15

02/14/2022

13-15 ft

AOI01-02-SB-13-15

02/16/2022

13-15 ft

AOI01-05-SB-04-05

02/15/2022

4-5 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

BHM-01-SB-13-15

02/15/2022

13-15 ft

Soil, LCMSMS compliant with QSM 5.3 Table B-15 (μg/kg)

AOI02-03-SB-10-12

02/14/2022

10-12 ft

AOI02-04-SB-08-10

02/14/2022

8-10 ft

AOI02-01-SB-10-12

02/15/2022

AECOM 
Table 6-4

PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Deep Subsurface Soil

Site Inspection Report, AASF #2 Birmingham

Area of Interest

Sample ID

Sample Date

Depth

Analyte Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual

PFBS ND U 0.031 J ND U ND U 0.029 J ND U ND UPFHxS ND U 0.140 J 0.046 J 0.062 J 0.217 J 0.365 J ND UPFNA ND U ND U ND U ND U ND U ND U ND UPFOA ND U ND U ND U ND U ND U ND U ND UPFOS ND U 0.393 J ND U 0.516 J 0.756 J 1.49 ND U

Interpreted Qualifiers Chemical AbbreviationsJ = Estimated concentration PFBS perfluorobutanesulfonic acidU = The analyte was not detected at a level greater than or equal to the adjusted DL PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

Notes PFOA perfluorooctanoic acidND = Analyte not detected above the LOD. LOD values are presented in Appendix F. PFOS perfluorooctanesulfonic acid

Acronyms and Abbreviations

AASF Army Aviation Support FacilityAOI Area of InterestBHM BirminghamD duplicateDL detection limitft feetID identificationLCMSMS liquid chromatography with tandem mass LOD limit of detectionND analyte not detected above the LODQSM Quality Systems ManualQual interpreted qualifierSB soil boringμg/kg micrograms per kilogram

BHM-01-SB-28-30

02/15/2022

28-30 ft

02/15/2022

22-24 ft

AOI01-02-SB-30-32

02/16/2022

30-32 ft

Soil, LCMSMS compliant with QSM 5.3 Table B-15 (μg/kg)

AOI01

AOI02-03-SB-18-20

02/14/2022

18-20 ft

AOI02-04-SB-15-16

02/14/2022

15-16 ft

AOI02-01-SB-19-21

02/15/2022

19-21 ft

AOI02

AOI02-02-SB-28-30

02/14/2022

28-30 ft

AOI01-01-SB-22-24

AECOM 
Table 6-5

PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Groundwater

Site Inspection Report, AASF #2 Birmingham

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual

PFBS 601 2.65 J 17.3 30.1 28.9 13.2 84.7 8.65

PFHxS 39 14.3 65.7 390 387 73.7 782 J 40.6

PFNA 6 ND U 2.57 J 2.97 J 2.72 J 1.38 J 14.6 ND U

PFOA 6 4.43 98.4 23.8 25.7 9.80 73.8 6.20

PFOS 4 10.6 9.98 119 133 54.9 697 J 91.7

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acidPFOA perfluorooctanoic acidPFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AASF Army Aviation Support FacilityU = The analyte was not detected at a level greater than or equal to the adjusted DL AOI Area of Interest

BHM Birmingham

Notes D duplicate

ND = Analyte not detected above the LOD. LOD values are presented in Appendix F. DL detection limit

GW groundwaterHQ hazard quotientID identificationLCMSMS liquid chromatography with tandem LOD limit of detectionND analyte not detected above the LODOSD Office of the Secretary of DefenseQSM Quality Systems ManualQual interpreted qualifierUSEPA United States Environmental Protecng/l nanogram per liter

Sample ID

Sample Date

AOI01-01-GW

02/16/2022

AOI02

Water, LCMSMS compliant with QSM 5.3 Table B-15 (ng/l)

a. Assistant Secretary of Defense, July 2022. Risk Based Screening Levels Calculated for PFOA, PFOS, PFBS, PFHxS, and PFNA in Groundwater or Soil using USEPA’s Regional Screening Level Calculator. HQ=0.1, May 2022 Groundwater screening levels based on residential scenario for direct ingestion of groundwater.

AOI01

AOI02-03-GW

02/15/2022

BHM-01-GW

02/16/2022

AOI02-01-GW-D

02/16/2022

AOI02-02-GW

02/15/2022

AOI01-02-GW

02/16/2022

AOI02-01-GW

02/16/2022

Area of Interest

AECOM 
THIS PAGE INTENTIONALLY BLANK

M 6-10
AOI01-01

AOI01-02

AOI01-05

AOI02-01

AOI02-02

AOI02-03

AOI02-04

BHM-01

AOI01-01

AOI01-02

AOI02-01

AOI02-02

AOI02-03

AOI02-04

BHM-01

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI01-05

AOI02-01

AOI02-02

AOI02-03

AOI02-04

BHM-01

AOI02-05

AOI02-06

­ Figure 6-1

CLIENT

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ARNG

8/24/2022

8/24/2022

8/24/2022

MS

MC

CM

GIS BY

CHK BY

PM

Base Map: Source: Esri, Maxar, Earthstar Geographics, and the GIS User Community

8/24/2022

1:2,400

Legend

Facility Boundary

PFOA Detections in Soil

12420 Milestone Center Drive

Germantown, MD 20876

Shallow Intermediate Deep

0 100 200 400

Feet

PROJECT Site Inspection at AASF #2, Birmingham, AL

PFOA Results (μg/Kg)

ND

>ND - 19

>19 - 250

>250 - 2,500

>2,500

Exceedances of the OSD SL are depicted with a yellow halo.

Depth intervals shown represent respective sampling position within a given soil boring location.

AECOM 6-11
AOI01-01

AOI01-02

AOI01-05

AOI02-01

AOI02-02

AOI02-03

AOI02-04

BHM-01

AOI01-01

AOI01-02

AOI02-01

AOI02-02

AOI02-03

AOI02-04

BHM-01

AOI01-01

AOI01-02

AOI01-03

AOI01-04 AOI01-05

AOI02-01

AOI02-02

AOI02-03

AOI02-04

BHM-01

AOI02-05

AOI02-06

­ Figure 6-2

CLIENT

REVISED

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ARNG

8/24/2022

8/24/2022

8/24/2022

MS

MC

CM

GIS BY

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Base Map: Source: Esri, Maxar, Earthstar Geographics, and the GIS User Community

8/24/2022

1:2,400

Legend

Facility Boundary

PFOS Detections in Soil

12420 Milestone Center Drive

Germantown, MD 20876

Shallow Intermediate Deep

0 100 200 400

Feet

PROJECT Site Inspection at AASF #2, Birmingham, AL

PFOS Results (μg/Kg)

ND

>ND - 13

>13 - 160

>160 - 1,600

>1,600

Exceedances of the OSD SL are depicted with a yellow halo.

Depth intervals shown represent respective sampling position within a given soil boring location.

AECOM 6-12
AOI01-01

AOI01-02

AOI01-05

AOI02-01

AOI02-02

AOI02-03

AOI02-04

BHM-01

AOI01-01

AOI01-02

AOI02-01

AOI02-02

AOI02-03

AOI02-04

BHM-01

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI01-05

AOI02-01

AOI02-02

AOI02-03

AOI02-04

BHM-01

AOI02-05

AOI02-06

­ Figure 6-3

CLIENT

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SCALE

ARNG

8/24/2022

8/24/2022

8/24/2022

MS

MC

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Base Map: Source: Esri, Maxar, Earthstar Geographics, and the GIS User Community

8/24/2022

1:2,400

Legend

Facility Boundary

PFBS Detections in Soil

12420 Milestone Center Drive

Germantown, MD 20876

Shallow Intermediate Deep

0 100 200 400

Feet

PROJECT Site Inspection at AASF #2, Birmingham, AL

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 6-13
AOI01-01

AOI01-02

AOI01-05

AOI02-01

AOI02-02

AOI02-03

AOI02-04

BHM-01

AOI01-01

AOI01-02

AOI02-01

AOI02-02

AOI02-03

AOI02-04

BHM-01

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI01-05

AOI02-01

AOI02-02

AOI02-03

AOI02-04

BHM-01

AOI02-05

AOI02-06

­ Figure 6-4

CLIENT

REVISED

SCALE

ARNG

8/24/2022

8/24/2022

8/24/2022

MS

MC

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GIS BY

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Base Map: Source: Esri, Maxar, Earthstar Geographics, and the GIS User Community

8/24/2022

1:2,400

Legend

Facility Boundary

PFHxS Detections in Soil

12420 Milestone Center Drive

Germantown, MD 20876

Shallow Intermediate Deep

0 100 200 400

Feet

PROJECT Site Inspection at AASF #2, Birmingham, AL

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 6-14
AOI01-01

AOI01-02

AOI01-05

AOI02-01

AOI02-02

AOI02-03

AOI02-04

BHM-01

AOI01-01

AOI01-02

AOI02-01

AOI02-02

AOI02-03

AOI02-04

BHM-01

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI01-05

AOI02-01

AOI02-02

AOI02-03

AOI02-04

BHM-01

AOI02-05

AOI02-06

­ Figure 6-5

CLIENT

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ARNG

8/24/2022

8/24/2022

8/24/2022

MS

MC

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Base Map: Source: Esri, Maxar, Earthstar Geographics, and the GIS User Community

8/24/2022

1:2,400

Legend

Facility Boundary

PFNA Detections in Soil

12420 Milestone Center Drive

Germantown, MD 20876

Shallow Intermediate Deep

0 100 200 400

Feet

PROJECT Site Inspection at AASF #2, Birmingham, AL

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 6-15
AOI01-01

AOI01-02

AOI02-01

AOI02-02

AOI02-03

BHM-01

AOI01-01

AOI01-02

AOI02-01

AOI02-02

AOI02-03

BHM-01

AOI01-01

AOI01-02

AOI02-01

AOI02-02

AOI02-03

BHM-01

­ Figure 6-6

CLIENT

REVISED

SCALE

ARNG

11/9/2022

11/9/2022

11/9/2022

MS

MC

CM

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Base Map: Source: Esri, Maxar, Earthstar Geographics, and the GIS User Community

11/9/2022

1:2,400

Legend

Facility Boundary

Groundwater Flow Direction

PFOA, PFOS, and PFBS Detections in Groundwater

12420 Milestone Center Drive

Germantown, MD 20876

PFOA PFOS PFBS

0 100 200 400

Feet

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

PFOS Results (ng/L)

ND

>ND - 4

>4 - 40

>40 - 70

>70

PROJECT Site Inspection at AASF #2, Birmingham, AL

Exceedances of the OSD SL are depicted with a yellow halo.

AECOM 6-16
AOI01-01

AOI01-02

AOI02-01

AOI02-02

AOI02-03

BHM-01

AOI01-01

AOI01-02

AOI02-01

AOI02-02

AOI02-03

BHM-01

­ Figure 6-7

CLIENT

REVISED

SCALE

ARNG

11/9/2022

11/9/2022

11/9/2022

MS

MC

CM

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Base Map: Source: Esri, Maxar, Earthstar Geographics, and the GIS User Community

11/9/2022

1:2,400

Legend

Facility Boundary

Groundwater Flow Direction

PFHxS and PFNA Detections in Groundwater

12420 Milestone Center Drive

Germantown, MD 20876

PFHxS PFNA

0 100 200 400

Feet

PFHxS Results (ng/L)

ND

>ND - 39

>39 - 100

>100 - 1,000

>1,000

PFNA Results (ng/L)

ND

>ND - 6

>6 - 100

>100 - 1,000

>1,000

PROJECT Site Inspection at AASF #2, Birmingham, AL

Exceedances of the OSD SL are depicted with a yellow halo.

AECOM 6-17
THIS PAGE INTENTIONALLY BLANK

6-18
Site Inspection Report

Army Aviation Support Facility #2, Birmingham, Alabama

AECOM 7-1

7. Exposure Pathways

The CSMs for each AOI, revised based on the SI findings, are presented on Figure 7-1 through 

Figure 7-2. 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 (though unlikely due to restricted access), 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, AOI 2, and Sitewide based on the 

aforementioned criteria. 

7.1.1 AOI 1 

AOI 1 is the Hangar, where AFFF may have been released during maintenance of the fire 

suppression system or through incidental leaks and spills of stored AFFF. Maintenance has been 

documented throughout the late 1990s, and AFFF in the system was last replaced in 2010. No 

information was available regarding the testing of the system. Releases at AOI 1 would have 

occurred on the Hangar floor or mechanical room, both of which drain to floor and trench drains, 
Site Inspection Report

Army Aviation Support Facility #2, Birmingham, Alabama

AECOM 7-2

which lead to an onsite OWS and then to the sanitary sewer. Therefore, discharges of AFFF in 

the Hangar would likely be captured and conveyed to the sanitary sewer system; however, they

may have infiltrated into the subsurface via joints in the floor slab or could have traveled outside 

the Hangar. AFFF releases outside the Hangar may have infiltrated into the subsurface soil or run 

off to the storm water sewer or onto the Flight Ramp and surrounding grassy areas. 

PFOA, PFOS, PFBS, PFHxS, and PFNA were detected in surface soil at AOI 1. Site workers and 

construction workers could contact constituents in surface soil via incidental ingestion and 

inhalation of dust. No ongoing construction was observed at the facility. Therefore, the soil 

exposure pathway for site workers and future construction workers are potentially complete. The 

facility is gated and there are no adjacent residential structures; therefore, the incidental ingestion 

and inhalation of dust exposure pathways for the trespasser, residential, and recreational user 

receptors are considered incomplete. PFOS and PFHxS were detected in shallow subsurface soil 

at depths above 15 feet bgs. The construction worker exposure scenario assumes excavation 

occurs at depths at or above 15 feet bgs. Therefore, the soil exposure pathway for incidental 

ingestion of subsurface soil by future construction workers is considered potentially complete. The 

CSM for AOI 1 is presented on Figure 7-1. 

7.1.2 AOI 2 

AOI 2 encompasses the Flight Ramp located south of the Hangar. Approximately 16 Tri-MaxTM 

30 mobile extinguisher units were staged on the Flight Ramp until 2010. No information was 

provided regarding the date the units were obtained or on the disposal of the units. There are no 

records of discharges or spills of AFFF at AOI 2. The pavement at the Flight Ramp drains via 

trench drains along the southern edge of the Flight Ramp to the storm water sewer. AFFF may 

have infiltrated into the subsurface soil via cracks or joints in the pavement or, where trench drains 

are not present, to the surrounding grassy areas.

PFOA, PFOS, PFBS, PFHxS, and PFNA were detected in surface soil at AOI 2. PFOS exceeded 

the residential SL in surface soil. Site workers and construction workers could contact constituents 

in soil via incidental ingestion and inhalation of dust. Therefore, the soil exposure pathway for site 

workers and future construction workers are potentially complete. The incidental ingestion and 

inhalation of dust exposure pathways for the trespasser, residential and recreational user 

receptors are considered incomplete for the same reasons as AOI 1. PFOS, PFBS, and PFHxS 

were detected in shallow subsurface soil at depths above 15 feet bgs. Therefore, the soil exposure 

pathway for incidental ingestion of subsurface soil by future construction workers is considered 

potentially complete. The CSM for AOI 2 is presented on Figure 7-2. 

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, and PFHxS were detected above their respective SLs in groundwater samples 

collected at AOI 1. Public drinking water and drinking water at the facility is supplied by 

Birmingham Water Works, who obtains the water from several surface water bodies which are 6 

and 9 miles southeast of the facility and not hydrologically connected to the facility. Therefore, the 

ingestion exposure pathway to site workers is considered incomplete. The nearest identified wells 

were possible public supply wells located over 3-miles southeast of the facility and screened over 

300 feet deep within the bedrock. Due to the distance and direction to the wells, and depths

relative to on-facility groundwater, the pathway for exposure to off-facility residents and 

recreational users via ingestion of groundwater is considered incomplete. Depths to water 
Site Inspection Report

Army Aviation Support Facility #2, Birmingham, Alabama

AECOM 7-3

measured in February 2022 during the SI ranged from 15.49 to 22.91 feet bgs. The construction 

worker exposure scenario assumes excavation occurs at depths of less than or equal to 15 feet 

bgs, however, seasonal changes in depths to water may bring the water table above 15 feet bgs. 

Therefore, the incidental groundwater exposure pathway is considered potentially complete for 

future construction workers during excavation at AOI 1. The CSM for AOI 1 is presented on Figure 

7-1.

7.2.2 AOI 2 

PFOA, PFOS, PFHxS, and PFNA were detected above their SLs in groundwater samples 

collected at AOI 2. The ingestion exposure pathway to site workers is considered incomplete

because municipal drinking water is sourced from surface water over 6 miles away. The pathway 

for exposure to off-facility residents and recreational users via ingestion of groundwater is also 

considered incomplete due to the distance, direction, and depth of the nearest potential supply 

wells. Depths to water measured in February 2022 during the SI ranged from 15.49 to 22.91 feet 

bgs, however, seasonal changes in depths to water may bring the water table above 15 feet bgs. 

Therefore, the incidental groundwater exposure pathway is considered potentially complete for 

future construction workers during excavation at AOI 2. The CSM for AOI 2 is presented on Figure 

7-2.

7.3 Surface Water and Sediment Exposure Pathway

Surface water and sediment samples were not collected during the SI field mobilization at 

Birmingham AASF #2. The SI results for 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. PFAS are water soluble and can 

migrate readily from soil to surface water via leaching and run-off. At AASF #2, storm water runoff 

north of the Hangar flows southwest along the AASF boundary. Storm water runoff on the Flight 

Ramp primarily flows across paved surfaces to the southeast. Storm water runoff at the facility is 

either captured by the sanitary system (i.e. building trench drains and wash rack), or flows into

trench drains at the southeast end of the Flight Ramp and into nearby storm drains. Storm water 

capture is inferred to join with the larger Airport system and drain southwest, towards Village 

Creek. Village Creek flows approximately 11 miles west of the facility to Bayview Lake.

7.3.1 AOI 1 

PFOA, PFOS, PFBS, PFHxS, and PFNA were detected in soil at AOI 1. It is possible that those 

compounds may have migrated from soil to Village Creek via overland flow. Storm water runoff 

from paved surfaces not captured by the sanitary sewer may also discharge to Village Creek, 

which flows southeast to southwest of AASF #2 and flows into Bayview Lake, located 11 miles 

west of the facility. Both Village Creek and Bayview Lake are used recreationally; therefore, the 

surface water and sediment ingestion exposure pathway for recreational users is considered 

potentially complete. Public drinking water and drinking water at the facility is supplied by 

Birmingham Water Works, who obtains the water from several surface water bodies which are 6 

and 9 miles southeast of the facility and not hydrologically connected to the facility. There are no 

surface water bodies located on the facility, therefore the exposure pathways for site workers, 

future construction workers, and off-facility residents are considered incomplete. The surface 

water and sediment exposure pathway is incomplete for trespassers due to the secure facility 

access. The CSM for AOI 1 is presented on Figure 7-1. 
Site Inspection Report

Army Aviation Support Facility #2, Birmingham, Alabama

AECOM 7-4

7.3.2 AOI 2 

PFOA, PFOS, PFBS, PFHxS, and PFNA were detected in soil at AOI 2. It is possible that those 

compounds may have migrated from soil to Village Creek via overland flow and further to Bayview 

Lake from Village Creek. Due to the recreational use of Village Creek and Bayview Lake, the 

surface water and sediment ingestion exposure pathway for recreational users is considered 

potentially complete. The exposure pathways for site workers, future construction workers, 

residents, and trespassers are considered incomplete for the same reasons as outlined in AOI 1. 

The CSM for AOI 2 is presented on Figure 7-2. 
Media

SOURCE PATHWAY RECEPTOR

AOI 1

AFFF Fire 

Suppression

System and

AFFF Storage

Subsurface

Soil

Human

Activities

Precipitation/

Run-Off

Leaching/

Infiltration

Airborne Soil

Particulate

Surface Soil

Surface

Water/

Sediment

Subsurface

Soil

Shallow

Groundwater

Source Release

Mechanism Media Transportand Migration Media ExposureRoutes

Inhalation of

Dust

Ingestion

Ingestion

Ingestion

Ingestion

Human Receptors:

Current/ Future

Flow-Chart Continues

Partial / Possible Flow

Flow-Chart Stops

Incomplete Pathway

Potentially Complete Pathway

Potentially Complete Pathway

with Exceedance of SL

/ / / /

LEGEND

Figure 7-1

Conceptual Site Model, AOI 1

AASF #2, Birmingham, Alabama

Potential 

Off-Facility 

Source Not 

Under 

Control of 

ARNG

Surface

Water

Surface

Water Flow

NOTES

1. The resident and recreational users

refer to off-site receptors.

Surface Soil

Site 

Worker

Construction 

Worker

Resident1 Recreational 

User/Trespasser1

/ / / /

/ / / /

/ / / /

/ / / /

Recreational 

User/Trespasser1

Site 

Worker

Construction 

Worker Resident1

AECOM 7-5
Media

SOURCE PATHWAY RECEPTOR

AOI 2

Accidental 

Leaks and

Spills of AFFF

Surface Soil

Subsurface

Soil

Human

Activities

Precipitation/

Run-Off

Leaching/

Infiltration

Airborne Soil

Particulate

Surface Soil

Surface

Water/

Sediment

Subsurface

Soil

Shallow

Groundwater

Source Release

Mechanism Media Transportand Migration Media ExposureRoutes

Inhalation of

Dust

Ingestion

Ingestion

Ingestion

Ingestion

Human Receptors:

Current/ Future

Flow-Chart Continues

Partial / Possible Flow

Flow-Chart Stops

Incomplete Pathway

Potentially Complete Pathway

Potentially Complete Pathway

with Exceedance of SL

LEGEND

/ / /

Figure 7-2

Conceptual Site Model, AOI 2

AASF #2, Birmingham, Alabama

Potential 

Off-Facility 

Source Not 

Under 

Control of 

ARNG

Surface

Water

Surface

Water Flow

NOTES

1. The resident and recreational users

refer to off-site receptors.

/

/ / / /

Site 

Worker

Construction 

Worker

Resident1

Recreational 

User/Trespasser1

/ / / /

Site 

Worker

Construction 

Worker Resident1

/ / / /

/ / / /

Recreational 

User/

Trespasser1

AECOM 7-6
Site Inspection Report

Army Aviation Support Facility #2, Birmingham, Alabama

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 14 to 17 February 2022 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, 2021), except as previously noted in Section 5.8. 

To fulfill the project DQOs set forth in the approved SI QAPP Addendum (AECOM, 2021), 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 12 boring locations;

• Six (6) grab groundwater samples from 7 temporary well locations; and

• 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 AOI 1: Hangar and AOI 

2: Flight Ramp. Based on the CSMs developed and revised in light of the SI findings, there is not 

the potential for exposure to drinking water receptors from AOI 1 and AOI 2 from sources on the

facility resulting from historical DoD activities. Sample analytical concentrations collected during 

the SI were compared to the project SLs in soil and groundwater, as described in Table 6-1. A 

summary of the results of the SI data relative to the SLs is as follows: 

• At AOI 1:

• The detected concentrations of PFOA, PFOS, PFHxS, PFNA, and PFBS in soil at

AOI 1 were below their respective SLs.

• PFOA, PFOS, and PFHxS in groundwater exceeded their SLs. PFOA exceeded the

SL of 6 ng/L, with a maximum concentration of 98.4 ng/L at location AOI01-02. PFOS

exceeded the SL of 4 ng/L at both AOI 1 sample locations, with a maximum

concentration of 10.6 ng/L at location AOI01-01. PFHxS exceeded the SL of 39 ng/L,

with a maximum concentration of 65.7 ng/L at location AOI01-02. Based on the

results of the SI, further evaluation of AOI 1 is warranted in an RI.
Site Inspection Report

Army Aviation Support Facility #2, Birmingham, Alabama

AECOM 8-2

• At AOI 2: 

• PFOS in surface soil exceeded the SL of 13 μg/kg, with a maximum concentration of 

64.5 μg/kg at location BHM-01. The detected concentrations of PFOA, PFHxS, 

PFNA, and PFBS in soil were below their SLs.

• PFOA, PFOS, PFHxS, and PFNA in groundwater exceeded their SLs. PFOA 

exceeded the SL of 6 ng/L, with a maximum concentration of 73.8 ng/L at location 

AOI02-03. PFOS exceeded the SL of 4 ng/L, with a maximum concentration of 697 

J ng/L at location AOI02-03. PFHxS exceeded the SL of 39 ng/L, with a maximum 

concentration of 782 J ng/L at location AOI02-03. PFNA exceeded the SL of 6 ng/L, 

with a maximum concentration of 14.6 ng/L at location AOI02-03. Based on the 

results of the SI, further evaluation of AOI 2 is warranted in an RI.

Of the six PFAS compounds presented in the 6 July 2022 OSD memorandum, HFPO-DA 

(commonly referred to as GenX) was not included as an analyte at the time of this SI. Based on 

the CSM developed during the PA and revised based on SI findings, the presence of HFPO-DA 

is not anticipated at the facility because HFPO-DA is generally not a component of MIL-SPEC 

AFFF and based on its history including distribution limitations that restricted use of GenX, it is 

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

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

Table 8-1 summarizes the SI results for soil and groundwater used to determine if an AOI should 

be considered for further investigation under CERCLA and undergo an RI. 

Table 8-1: Summary of Site Inspection Findings and Recommendations

AOI

Potential 

Release 

Area

Soil – 

Source Area

Groundwater – 

Source Area

Groundwater –

Facility 

Boundary

Future Action

1 Hangar N/A Proceed to RI 

2 Flight Ramp Proceed to RI

Legend:

N/A = Not Applicable

= detected; exceedance of the screening levels

= detected; no exceedance of the screening levels

= not detected
Site Inspection Report

Army Aviation Support Facility #2, Birmingham, Alabama

AECOM 9-1

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