FINAL

Site Inspection Report 

Army Aviation Support Facility #1 

R W Shepherd,

Montgomery, 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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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....................................................................................................2-4

2.2.4 Climate........................................................................................................2-4

2.2.5 Current and Future Land Use......................................................................2-4

2.2.6 Sensitive Habitat and Threatened/ Endangered Species.............................2-4

2.3 History of PFAS Use..............................................................................................2-5

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

3.1 AOI 1 Hangar Fire Suppression System, Mechanical Room, and Hazardous 

Waste Storage Room........................................................................................3-1

3.2 AOI 2 Flight Ramp and Wash Rack.......................................................................3-2

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....................................................................................4-2

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...............................5-4

5.4 Surface Water .......................................................................................................5-5

5.5 Synoptic Water Level Measurements ....................................................................5-5

5.6 Surveying..............................................................................................................5-5

5.7 Investigation-Derived Waste..................................................................................5-5

5.8 Laboratory Analytical Methods ..............................................................................5-6

5.9 Deviations from SI QAPP Addendum ....................................................................5-6

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 Surface Water Analytical Results.......................................................6-3
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6.3.3 AOI 1 Conclusions ......................................................................................6-3

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

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

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

6.4.3 AOI 2 Surface Water Analytical Results.......................................................6-5

6.4.4 AOI 2 Conclusions ......................................................................................6-5

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...........................................................................................................7-2

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

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

7.3.2 AOI 2...........................................................................................................7-3

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

Appendix C Photographic Log

Appendix D TPP Meeting Minutes

Appendix E Boring Logs and Well Construction Forms 

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 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 6-8 PFOA, PFOS, and PFBS Detections in Surface Water

Figure 6-9 PFHxS and PFNA Detections in Surface Water

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 

Levels

Table 6-1 Screening Levels (Soil and Groundwater)

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

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

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

Table 6-5 PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Surface Water

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

ANGB Air National Guard Base

AOI Area of Interest

ARNG Army National Guard

ASTM American Society for Testing and Materials

bgs below ground surface 

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act 

CoC chain of custody

CSM conceptual site model

CSMS Combined Support Maintenance Shop

DA Department of the Army

DoD Department of Defense

DO dissolved oxygen

DOT Department of Transportation

DPT direct push technology

DQO data quality objective

DUA data usability assessment

EDRTM Environmental Data Resources, Inc.TM

ELAP Environmental Laboratory Accreditation Program

EM Engineer Manual

FedEx Federal Express

FTA Fire Training Area

GPS Global positioning system

GRPS Ground Penetrating Radar Systems

HDPE high-density polyethylene 

HFPO-DA hexafluoropropylene oxide dimer acid

HSA hollow stem auger

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

MWWSSB Montgomery Water Works and Sanitary Sewer Board

NELAP National Environmental Laboratory Accreditation Program

ng/L nanograms per liter

ORP oxidation-reduction potential
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OSD Office of the Secretary of Defense

OWS oil water separator

PA Preliminary Assessment

PFAS per- and polyfluoroalkyl substances

PFBS perfluorobutanesulfonic acid

PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

PID photoionization detector

PQAPP Programmatic UFP-QAPP

PRL potential release location

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

UCMR 3 Third Unregulated Contaminant Monitoring Rule

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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Executive Summary

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

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

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

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

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

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

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

, and perfluorobutanesulfonic acid 

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

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

The PA identified 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 Army Aviation Support Facility (AASF) #1 in 

Montgomery, Alabama and determined further investigation is warranted for AOI 1: Hangar Fire 

Suppression System, Mechanical Room, and Hazardous Waste Storage Room and AOI 2: Flight 

Ramp and Wash Rack. AASF #1 will also be referred to as the “facility” throughout this document.

AASF #1 is situated on a 160-acre parcel of land owned by the Montgomery Airport Authority 

(Montgomery County, 2019). The facility is located in southwest Montgomery, in Montgomery 

County, Alabama. The facility property is within the Montgomery Regional Airport, at the 

southernmost portion of the airport property, off US Highway 80 (Selma Highway). According to 

Alabama ARNG (ALARNG) personnel, the facility was constructed in 1995. The current AASF #1 

facilities include one hangar for the operation, maintenance, and repair of ALARNG rotary-winged 

aircraft, administrative offices, and classrooms (AECOM Technical Services, Inc. [AECOM], 

2020). 

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 Fire Suppression System, Mechanical Room, and Hazardous Waste Storage 

Room and AOI 2: Flight Ramp and Wash Rack.

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

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

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

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

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

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

Analyteb

Residential

(Soil)

(μg/kg)a 

0-2 feet bgs

Industrial/ Commercial 

Composite Worker

(Soil)

(μg/kg)a 

2-15 feet bgs

Tap Water

(Groundwater)

(ng/L)a

PFOA 19 250 6

PFOS 13 160 4 

PFBS 1,900 25,000 601 

PFHxS 130 1,600 39

PFNA 19 250 6

Notes:

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

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

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

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

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

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

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

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

AOI Potential 

Release Area

Soil – 

Source Area

Groundwater – 

Source Area

Groundwater –

Facility 

Boundary

Future 

Action

1 

Hangar Fire Suppression 

System, Mechanical Room, 

and Hazardous Waste 

Storage Room

N/A1 N/A Proceed 

to RI 

2 Flight Ramp and 

Wash Rack

N/A Proceed 

to RI

Legend:

1. Groundwater was not encountered within AOI 1 at the time of the SI

N/A = not applicable

= detected; exceedance of the screening levels

= detected; no exceedance of the screening levels

= not detected
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1. Introduction

1.1 Project Authorization

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

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

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

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

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

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

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

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

, and perfluorobutanesulfonic 

acid (PFBS) at ARNG facilities nationwide. The ARNG performed this SI at Army Aviation Support 

Facility (AASF) #1 in Montgomery, Alabama. AASF #1 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 AASF #1 (AECOM Technical Services, Inc. [AECOM], 2020) that identified 

two Areas of Interest (AOIs) where PFAS-containing materials may have been used, stored, 

disposed, or released historically. The objective of the SI is to identify whether there has been a 

release to the environment from the AOIs identified in the PA and determine whether further 

investigation is warranted, a removal action is required to address immediate threats, or no further 

action is required based on screening levels (SLs) for the relevant compounds. 

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

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

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

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

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

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

2.1 Facility Location and Description

AASF #1 is situated on a 160-acre parcel of land owned by the Montgomery Airport Authority 

(Montgomery County, 2019). The facility is located approximately 7.5 miles southwest of

downtown Montgomery, in Montgomery County, Alabama. The facility property is within the 

Montgomery Regional Airport, at the southernmost portion of the airport property, off US Highway 

80 (Selma Highway) (Figure 2-1). The latitude and longitude for the approximate center of the 

AASF are 32°17’10.84” N; 86°23’42.60” W. According to Alabama ARNG (ALARNG) personnel, 

the facility was constructed in 1995.

The current AASF #1 facilities include one hangar for the operation, maintenance, and repair of 

ALARNG rotary-winged aircraft. The facility also maintains administrative offices, classrooms, and 

a readiness center. An approximately 2,500-feet-long taxiway extends from the north end of the 

AASF #1 flight ramp, connecting it to the Montgomery Regional Airport airfield. Water, electric, 

and sewer utilities are provided by the City of Montgomery. 

2.2 Facility Environmental Setting

AASF #1 is situated in the Black Prairie Belt district of the Coastal Plain physiographic province. 

The Black Prairie Belt occupies a crescent shaped area extending from northern Mississippi into 

central Alabama and is characterized by an undulating, deeply weathered plain of low relief. AASF 

#1 is situated on a generally level parcel of land at an elevation of around 230 to 240 feet above 

mean sea level (Figure 2-2). Gentle hills rise to the northwest and southeast of the facility. The 

facility lies in the Southeastern Plains ecoregion, which is characterized by smooth to irregular 

plains or flatlands separated in some places by curved bands of asymmetrical ridges and rugged 

hills. Streams draining this ecoregion are generally low gradient, with silty sand substrates. Forest 

and woodland areas are prevalent and are part of the mosaic of cropland, pasture, and urban 

areas that dot the landscape. Natural vegetative cover includes oak, hickory, pine, and southern 

mixed forests (Geological Survey of Alabama, 2002).

AASF #1 is roughly 50% covered with developed and paved surfaces. The majority of the 

unimproved lands are open fields located to the north and southeast of the hangar. The area 

immediately surrounding the facility includes the Montgomery Regional Airport to the north, rural 

residential properties to the east and south, and agricultural land to the west. Commercial 

properties exist to the north and southeast. 

2.2.1 Geology

Near-surface strata in the region consist of Quaternary alluvium and Pleistocene terrace deposits. 

The alluvium deposits are found predominantly along the valleys of the nearby Pintlala and 

Catoma Creeks and their tributaries. The deposits measure 0 to 40 feet thick and are 

characterized by white to light-gray, silty, poorly sorted sand with yellow, gray-orange to bluishgray, sandy clay lenses. The Pleistocene terrace deposits are remnants of the channels of the 

ancestral Alabama River and are found in a band approximately 6 to 8 miles wide that is parallel 

to the present-day river. The thicknesses of the terrace deposits range from 10 to 100 feet and 

are characterized by pale-yellowish-orange, cross-bedded, medium to very coarse grained, 

poorly-sorted sand; dark-reddish-brown sandy clay; and lenses of well-rounded gravel 

(Geological Survey of Alabama, 1963). 

Selma Group rocks of Late Cretaceous age unconformably underlie the Pleistocene Terrace 

Deposits. Selma group rocks include all Upper Cretaceous strata above the Eutaw Formation. 
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Stratigraphic units of the Selma Group, in descending order, include Providence Sand, Prairie 

Bluff Chalk, Ripley Formation Sands, Demopolis Chalk, and Mooresville Chalk. Units of the Selma 

Group are relatively impermeable or have low groundwater permeability. The Mooresville Chalk 

is the primary unit mapped at the surface of the facility. This unit is prevalent across north-central 

Montgomery County and is characterized in the western part of the county as a gray to pale-olive 

silty to fine sandy, fossiliferous chalk that can be present up to 600 feet thick in some areas. The 

northern portion of the aforementioned Black Prairie has developed on the Mooresville Chalk, 

where it forms gently rolling terrain with deep black soils that grow natural grasslands (Geological 

Survey of Alabama, 1963). 

The Eutaw Formation unconformably underlies the Mooresville Chalk. The Eutaw Formation 

outcrops in small areas in the region north of Montgomery but typically ranges in depth from 3 

feet below ground surface (bgs) northeast of Montgomery to 405 feet bgs southwest of 

Montgomery. The Eutaw formation consists of light-greenish-gray, cross laminated, fine to 

medium-grained, well-sorted, micaceous, glauconitic, fossiliferous sand interbedded with 

greenish-gray micaceous glauconitic fossiliferous clay and sandy clay (Geological Survey of 

Alabama, 1963). Additionally, the Eutaw formation contains beds of greenish-gray micaceous, 

silty clay and medium-dark-gray carbonaceous clay (Geological Survey of Alabama, 1988).

The Gordo Formation unconformably underlies the Eutaw formation and is characterized by paleyellowish-orange medium to coarse grained, poorly sorted, ferruginous-cemented sand 

interbedded with moderate-reddish-brown to pale-red-purple clay. The Coker Formation 

unconformably underlies the Gordo Formation and consists of light-greenish-gray, medium- to 

coarse-grained, well-sorted, fossiliferous sand that is thinly laminated with greenish-gray, lignitic, 

fossiliferous clay. Basement rock unconformably below the Cocker Formation is characterized by 

Pre-Cretaceous crystalline, biotite, mica schist (Geological Survey of Alabama, 1963).

The majority of the SI soil borings were completed to depths ranging between 20 to 27.5 feet bgs, 

with the exception of AOI02-05, which was completed to 59 feet bgs. Surface and subsurface soil 

encountered generally consisted of low to medium plasticity lean clays which were noted to swell 

at most borings. Some sand was observed within these massive clay layers at several borings. 

A high plasticity fat clay layer was observed near the surface at AOI02-02. The clay encountered 

ranged in color between yellowish brown, gray, and dark greenish gray. The impermeable clays 

and trace amounts of silt and fine sands encountered are consistent with the Mooresville Chalk 

of the Selma Group. These observations are consistent with the understood marine depositional 

environment of the units in the region.

Water bearing units were generally not encountered during SI drilling except for very trace 

amounts of water in the shallow subsurface. Non-plastic silt with varying amounts of sand was 

encountered at several borings within AOI 2 from the surface level to depths up to 5 feet bgs. This 

slightly more permeable material is likely fill or reworked native soils introduced during

construction. 

Samples for grain size analysis was collected at AOI01-01 from 18 to 20 feet bgs and analyzed 

by American Society for Testing and Materials (ASTM) Method D-422. The results indicate that 

the soil sample is mostly silt (72.51 percent [%]) and clay (26.20%). Boring logs are presented in 

Appendix E, and grain size results are presented in Appendix F.

2.2.2 Hydrogeology

Sand beds in the Quaternary alluvium sediments yield small quantities of water in shallow wells 

installed in the region at depths from less than 10 to about 30 feet bgs. Some users of these wells 

experience water shortages during times of limited rainfall; however, some wells installed in 

topographically lower areas and near streams can produce water year-round. Sand and gravel 

beds of the Pleistocene terrace deposits are very permeable and yield moderate to large supplies 
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of water. Wells installed in these sand and gravel beds are used for industrial, domestic, and stock 

use (Geological Survey of Alabama, 1963).

The units within the Selma Group consist of relatively impermeable, fine-grained or cemented 

rocks that are not generally considered suitable aquifers for water production. While some wells 

do exist within several of these formations, they provide limited amounts of water and are not 

used for the municipal water supply. The Mooresville Chalk is not recognized as an aquifer in 

Montgomery County due to its impermeability, but rather, it is considered the confining unit above 

the underlying Eutaw formation (Geological Survey of Alabama, 1963). 

The Eutaw and Coker formations are among the most productive aquifers in Montgomery County.

Large quantities of water are pumped from these formations for municipal use by the City of 

Montgomery. Wells located west of Montgomery that are screened in the Eutaw are generally 

screened in the lower portion of the formation, where the iron content is lower. The Coker 

formation serves as the principal aquifer of Montgomery County, where the upper part of the 

formation has been developed extensively for municipal well use. The Gordo formation, which 

lies between the Eutaw and Coker, is not widely used as a water supply (Geological Survey of 

Alabama, 1963). 

Based on the flow patterns of larger surface water features, general groundwater flow beneath 

the facility was inferred toward the northwest. An Environmental Data Resources, Inc.TM (EDRTM) 

report conducted a well search for a 1-mile radius surrounding the facility (Appendix A of AECOM, 

2020); no groundwater wells were identified within a 1-mile radius of AASF #1. Using additional 

online resources, such as state and local Geographic Information System databases, wells were 

researched to a 4-mile radius of the facility. The only wells able to be identified within the 4-mile 

search radius were active and inactive US Geological Survey (USGS) monitoring wells. 

Groundwater features in the vicinity of the facility are shown on Figure 2-3. There are currently 

no potable water wells at the facility.

Drinking water at the facility is supplied by the City of Montgomery, which receives its water from 

groundwater and surface water sources. Surface water from the Tallapoosa River makes up 

approximately two thirds of the City of Montgomery’s drinking water supply, while groundwater 

from the city’s west and southwest well fields makes up the remaining one third (Montgomery 

Water Works and Sanitary Sewer Board [MWWSSB] of the City of Montgomery, 2018). The 

Tallapoosa River is located approximately 15 miles northeast of AASF #1. The locations of the 

west and southwest well fields could not be ascertained from public records; however, an SI 

conducted at the Montgomery Air National Guard Base (ANGB), on the northern portion of the 

Montgomery Airport property, suggests the west well field is located approximately 4.25 miles 

north of AASF #1 (AECOM, 2019). 

During the January 2022 SI, groundwater was only encountered in three of the six temporary 

monitoring wells and appeared to be present only within the upper several feet of the subsurface, 

where the disturbed soils were slightly more permeable. Depths to water measured at the three 

locations ranged from 0.40 to 19.44 feet bgs. Based on the groundwater depths and widespread 

clay units, the groundwater encountered appeared to be consistent with very shallow perched 

groundwater and not representative of actual groundwater. Water measured deeper within the 

clay is suspected to have filled the borehole from above.

Due to the groundwater observations showing very localized, perched conditions, groundwater 

measurements were not considered representative of a true potentiometric surface and the 

groundwater flow direction at the facility could not be properly evaluated. Groundwater flow in the 

deeper subsurface, beneath the observed impermeable clays, is not known but is assumed to 

flow toward the northwest, as inferred from the topography and flow patterns of surrounding larger 

surface water features.
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Based on the very shallow, perched groundwater conditions and swelling clay observed during the 

SI, surface water runoff appears to be the primary mechanism of hydrologic transport at the facility, 

with infiltration being the secondary and less substantial mechanism of hydrologic transport.

2.2.3 Hydrology

AASF #1 lies within the Alabama River Basin (Geological Survey of Alabama, 2002). The facility 

straddles a northwest-southeast-trending watershed divide. The Middle Pintlala Creek Watershed 

drains the majority of the facility, including the hangar and flight ramp areas, towards Pintlala 

Creek to the southwest. Surface water in the northeast-most part of the facility, the area along the 

taxiway, drains via the Caney Branch Watershed towards Catoma Creek to the northeast. Pintlala 

Creek and Catoma Creek are roughly equidistant from the facility, each located approximately 2.5 

miles to the southwest and northeast, respectively. Both creeks flow for over 5 miles to the 

northwest, into the Alabama River. 

On-facility surface water generally drains via sheet flow to the west-northwest; however, surface 

water at the edges of the flight ramp and paved areas surrounding the hangar flow radially into 

unpaved areas. Two low-lying retention areas were identified to the west-southwest of the flight 

ramp (Retention Area 1) and southeast of the mechanical room (Retention Area 2). Retention 

Area 1 appears to be wet throughout most of the year and may flow off-facility during high water 

conditions southward via an intermittent stream. Retention Area 2 is a smaller, vegetated basin

that is largely dry throughout the year except for a small area just southeast of the hangar building. 

Retention Area 2 does not appear to drain off-facility, as no outflow was identified, and low berms 

are present south of the basin. Floor and trench drains, including a drain within the wash rack 

(east of the flight ramp), convey to the sanitary sewer. Surface water features surrounding the 

facility are shown in Figure 2-4. 

2.2.4 Climate

Alabama’s climate is humid subtropical, with average annual temperatures of about 65 degrees 

Fahrenheit (°F) in the City of Montgomery, with an average high of 76.5 °F and an average low of 

53.5 °F. Rainfall in Alabama usually is abundant and distributed throughout the year. Montgomery 

receives an average of 53.05 inches of rain per year (World Climate, 2022). 

2.2.5 Current and Future Land Use

The ALARNG AASF #1 facility is located within the Montgomery Regional Airport. Properties 

surrounding the AASF #1 facility primarily consist of commercial properties to the north and 

southeast, rural residential properties to the east and south, and agricultural properties to the 

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

2.2.6 Sensitive Habitat and Threatened/ Endangered Species 

The following birds, clams, insects, reptiles, snails, and flowering plants are federally endangered, 

threatened, proposed, and/ or are listed as candidate species in Montgomery County, Alabama

(US Fish and Wildlife Service [USFWS], 2022). 

• Birds: Wood stork, Mycteria americana (threatened)

• Clams: Southern Clubshell, Pleurobema (endangered), Southern kidneyshell 

Ptychobranchus jonesi (endangered), Choctaw bean, Obovaria choctawensis

(endangered), Southern Sandshell, Hamiota australis (threatened), Narrow pigtoe, 

Fusconaia escambia (threatened), Fuzzy pigtoe, Pleurobema strodeanum (threatened)
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• Insects: Monarch butterfly, Danaus plexippus (candidate)

• Reptiles: Gopher tortoise, Gopherus polyphemus (endangered), Alligator snapping turtle, 

Macrochelys temminckii (proposed threatened)

• Snails: Tulotoma snail, (Tulotoma magnifica) (threatened)

• Flowering plants: Alabama canebrake pitcher-plant, Sarracenia rubra ssp. Alabamensis

(endangered), Georgia rockcress, Arabis georgiana (threatened)

2.3 History of PFAS Use

Two AOIs where AFFF may have been used, stored, disposed, or released historically at the 

AASF #1 were identified in the PA (AECOM, 2020). AFFF may have historically been released at 

the facility during the replacement of AFFF within the 800-gallon hangar fire suppression system 

tanks between 2006 and 2009. During the process of replacing the AFFF, an unknown quantity of 

AFFF was spilled outside of the south side of the mechanical room and consequently killed the 

grass. Additionally, a 5-gallon jug of 3% AFFF concentrate was observed in the hazardous waste 

storage room during the PA site visit. Facility personnel subsequently placed the 5-gallon 

container of AFFF into a 20-gallon overpack container to prevent an accidental release.

Mobile AFFF “Tri-MaxTM 30” extinguisher units were staged along the flight ramp from 2001 to 

2017. The Tri-MaxTM 30 units may have also been used at the wash rack, located south of the 

hangar building, and are thought to have been emptied at the facility prior to their removal in 2017.

The potential release areas were grouped into two AOIs based on preliminary data and presumed 

groundwater flow directions. A description of each AOI is presented in Section 3.
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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, four potential release areas were 

identified at AASF #1 and grouped into two AOIs (AECOM, 2020). A fifth potential release area 

(the hazardous waste storage room) was added to AOI 1, after the submittal of the 2020 PA, in 

order to be consistent with the programmatic practice that any AFFF storage be considered a 

potential release area. The potential release areas are shown on Figure 3-1.

3.1 AOI 1 Hangar Fire Suppression System, Mechanical Room, and 

Hazardous Waste Storage Room

AOI 1 consists of three potential release areas: the hangar fire suppression system, mechanical 

room, and hazardous waste storage room. The AASF #1 hangar contains an overhead fire 

suppression system supplied by two 800-gallon tanks filled with AFFF concentrate. Both tanks 

are located in the mechanical room at the southeast corner of the hangar. In addition to the 

overhead system, the hangar building is equipped with smaller stationary floor tanks, also filled 

with AFFF, located on the hangar floor. The current AFFF suppression system was installed in 

1995 and was part of the original hangar construction. According to interviews with ALARNG 

personnel with knowledge of the property dating back to 2000, a full-scale test of the system was 

not conducted, and the system has not been triggered; however, information regarding any earlier 

testing from 1995 to 2000 could not be ascertained. It is reasonable to assume that an acceptance 

test was conducted prior to ALARNG accepting the system installation. 

According to ALARNG personnel, the AFFF concentrate in the 800-gallon tanks was replaced 

with AFFF of the same concentration between 2006 and 2009. During the process of replacing 

the AFFF, an unknown quantity of AFFF was spilled outside of the south side of the mechanical 

room and consequently killed the grass. The manufacturer of the historical and current AFFF is 

unknown. Additionally, information regarding where the original AFFF was disposed of was not 

known by ALARNG personnel and could not be ascertained. 

During the visual inspection, metal corrosion and rust staining were observed on both 800-gallon 

AFFF concentrate tanks in the mechanical room as well as the floor tanks within the hangar 

building. Corrosion was not evident when observing the overhead suppression system in the 

hangar building. Trench drains are located at the north and south ends of the hangar building,

and additional floor drains were noted within the hangar and mechanical room. 

The hazardous waste storage room is located on the west side of the hangar building. A 5-gallon 

jug of 3% AFFF concentrate was observed in the hazardous waste storage room during the PA 

site visit. ALARNG personnel noted that the jug was left over when AFFF in the hangar fire 

suppression system was replaced between 2006 and 2009. The AFFF jug was presumably left in 

the mechanical room to top off the 800-gallon concentrate tanks. Prior to the PA visit, ALARNG 

personnel had relocated the AFFF jug to the hazardous waste storage room. While AFFF is not 

classified as a hazardous waste, the jug was relocated to the hazardous waste storage room until 

proper disposal could be determined. Visual inspection of the jug indicated corrosion and leakage 

from the cap; however, it was noted that the jug was stored in secondary containment.

Any releases at AOI 1 could have occurred on the hangar floor or mechanical room, both of which 

drain to floor and trench drains. These drains would convey any AFFF to the oil water separator 

(OWS) and then to the sanitary sewer. According to ALARNG personnel, wastewater from the 

AASF #1 facility goes to the Catoma Wastewater Treatment Plant (WWTP) located approximately 

6 miles northwest of the facility. Biosolids generated from wastewater treatment at the Catoma 

WWTP are spread at two sites near the WWTP (MWWSSB, 2021). Other releases may have 
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AECOM 3-2

occurred directly to the building floor slab, including at the hazardous waste storage area. It is 

possible AFFF may have infiltrated into the subsurface soil via joints in the slab or could have 

traveled outside onto the flight ramp and surrounding grassy areas. AFFF is known to have been 

released to the unpaved, grassy area south of the mechanical room during the replacement of 

the AFFF from the 800-gallon concentrate tanks. 

3.2 AOI 2 Flight Ramp and Wash Rack

AOI 2 consists of two potential release areas: Flight Ramp and Wash Rack. The AOI 

encompasses the flight ramp located west of the hangar building. According to ALARNG 

personnel with knowledge of the facility dating back to 2000, approximately 10 mobile AFFF TriMaxTM 30 extinguisher units were staged along the flight ramp from 2001 to 2017. These units 

were reportedly transported off-facility in 2017 and replaced with the mobile Purple K units 

currently used at the facility. The Tri-MaxTM 30 units were transported to the combined 

maintenance shop (CSMS) at the Alabama National Guard office in Montgomery, Alabama. 

According to CSMS personnel, the Tri-MaxTM 30 units were received empty; however, information 

regarding how the Tri-MaxTM 30 units were emptied could not be ascertained by ALARNG 

personnel at AASF #1. Based on this discrepancy, it may be assumed that the Tri-MaxTM 30 units 

were discharged on the facility prior to transportation to CSMS. 

The wash rack is located south of the hangar building and is used to wash aircrafts. The wash 

rack is sloped on all sides towards one drain in the center of the wash rack that empties to the 

OWS, where it would combine with drainage from the hangar and mechanical room and then 

convey to the sanitary sewer system. ALARNG personnel with knowledge of the facility dating 

back to 2000 stated that ALARNG used aircraft soap at the wash rack area to simulate firefighting 

techniques and did not use fire or AFFF for these simulations. It is reasonable to assume that the

Tri-MaxTM 30 units staged along the Flight Ramp could have been used at the wash rack, or that 

the Tri-MaxTM 30 units may have been emptied at this location prior to being transported to the 

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

may have infiltrated into the subsurface soil via cracks or joints in the pavement or runoff to the 

surrounding grassy areas. 

3.3 Adjacent Sources

The Montgomery ANGB is located adjacent to the Montgomery Regional Airport and 

approximately 1.25 miles northwest of the facility. Aircraft support operations at Montgomery 

ANGB include aircraft fueling and maintenance, aircraft deicing, fire protection and support, 

ground vehicle fueling and maintenance, and equipment and facilities maintenance (AECOM, 

2019). Previous PA documentation for the Montgomery ANGB indicates that fire training was not 

performed within the facility boundary. However, a fire training area (FTA) was identified 

approximately 0.5 miles southeast of the Montgomery ANGB facility and across the East-West 

Runway on Airport property. According to this PA, fire training took place circa 1989 and 1991 and 

was conducted jointly with airport authority. During each exercise, an unknown quantity of spent 

fuel was ignited and extinguished using AFFF (BB&E, Inc., 2016). 

An SI was performed at the Montgomery ANGB from December 2017 to March 2018, in areas 

deemed as potential release locations (PRLs). A total of six PRLs were investigated during the 

SI. Results of the SI indicated that PFAS were present in all media sampled at each PRL. 

Additionally, PFAS detected in base boundary wells indicate that off-base migration of PFAS is 

possible (AECOM, 2019). Based on the findings of the SI report, the Montgomery ANGB is 

considered an off-facility source of PFAS. The location of the Montgomery ANGB and Montgomery 

Regional Airport are shown on Figure 3-1 for informational purposes but will not be evaluated as 

part of this SI.
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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 #1 (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); 

• Analytical data collected from surface water samples added during field work in response to 

the evolved understanding of the conceptual site model (CSM) that suggests surface runoff 

may be the primary mechanism for hydrologic transport at the facility (Section 5.9); 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 massive clay unit observed beneath the entire 

facility, and the resulting decision to not penetrate this potentially confining unit. Temporal boundaries 

of the study 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).
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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 

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 Site Inspection Programmatic Uniform Federal Policy-Quality Assurance Project Plan 

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

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

• Final Preliminary Assessment Report, AASF #1 RW Shepherd, Montgomery, Alabama

dated September 2020 (AECOM, 2020);

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

AASF #1 R W Shepherd Hope Hull, Montgomery, Alabama dated November 2021

(AECOM, 2021);

• Final Site Safety and Health Plan, AASF #1 R W Shepherd Hope Hull, Montgomery, 

Alabama dated January 2022 (AECOM, 2022).

The SI field activities were conducted from 18 to 21 January 2022 and consisted of utility clearance,

direct push boring, hollow stem augering, soil sample collection, temporary monitoring well 

installation, grab groundwater sample collection, and grab surface water sample collection. Field 

activities were conducted in accordance with the SI QAPP Addendum (AECOM, 2021), except as 

noted in Section 5.9.

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 13 locations; 

• Three grab groundwater samples from six temporary wells; 

• Two surface water samples from two surface water bodies; and

• Twenty (20) 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, and Field Change Request Forms

are provided in Appendix B3. 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.) 
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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 

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 G-9, ALARNG, and USACE. 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 contractor, Walker-Hill Environmental, contacted Alabama 811 onecall utility clearance contractor prior to mobilization to notify them of intrusive work. Because 

Alabama 811 locators do not locate private utilities, such as those belonging to AASF #1, AECOM 

contracted Ground Penetrating Radar Systems, LLC. (GPRS) to perform utility clearance for 

private utilities at all boring locations. GPRS performed the utility clearance under the oversight 

of the AECOM field team on 18 January 2022 using industry standard methods in addition to 

ground-penetrating radar. Additionally, the first 5 feet of the direct-push borings were advanced 

using hand augering methods to visually verify utility clearance in the shallow subsurface where 

utilities would typically be encountered.

5.1.3 Source Water and Sampling Equipment Acceptability

The potable water source used for decontamination of drilling equipment was confirmed to be 

acceptable for decontamination of drilling equipment. Samples from two potable water sources at 

the facility were collected on 16 November 2021 (MGM-DECON-01 and MGM-DECON-02), prior 

to mobilization, and analyzed by LC/MS/MS compliant with QSM 5.3 Table B-15. An additional 

sample was collected on 21 January 2022 (MGM-DECON-03), during SI field activities, from the 

same water after it passed through the driller’s decontamination water tank and hose. 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

Soil samples were collected via DPT, in accordance with the SI QAPP Addendum (AECOM, 

2021). A GeoProbe® 7822DT dual-tube sampling system was used to collect continuous soil cores 

to the target depth. At one location (AOI02-05), 3.25-inch diameter hollow stem augers (HSAs) 

were used from 20 feet bgs to 59 feet bgs to drill into the swelling clays where refusal was 

encountered during DPT drilling. As discussed in Section 5.9, the clay layer was not penetrated, 

and subsequent borings were advanced using only the dual-tube sampling system to refusal. A 
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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 5-2. 

In general, three discrete soil samples were collected for chemical analysis from each soil boring: 

one surface soil sample (0 to 2 feet bgs), one subsurface soil sample from approximately 13 to 

15 feet bgs, and one subsurface soil sample at a point between the surface and 15 feet bgs.

However, at AOI01-01, a total of four soil samples were collected to add vertical data density at 

the potential release area near the mechanical room. Additionally, a total of two soil samples were 

collected from AOI02-05. 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.

The majority of the SI soil borings were completed to depths ranging between 20 to 27.5 feet bgs, 

with the exception of AOI02-05, which was completed to 59 feet bgs to assess the vertical extent 

of the clay unit. Soil borings completed during the SI generally found low to medium plasticity lean 

clay. Non-plastic silt with varying quantities of sand was encountered at three DPT borings within 

AOI 2 from the surface level to depths up to 5 feet bgs. The silt and sand encountered in the 

shallow subsurface is considered reworked native material or introduced fill from construction of 

the facility. 

A high plasticity fat clay layer was observed within AOI02-02. DPT drilling and sampling refusal 

was observed in boring AOI02-05 at a depth of 20 feet bgs due to stiff, swelling clays encountered 

at 10 feet bgs and below. The clays expanded within the sampling cores to two times the length 

of the actual advanced interval (i.e., 5-foot core recovery over a 2.5-foot DPT run). DPT refusal 

was encountered at approximately 20 feet bgs. Since groundwater was not observed at 20 feet 

bgs, HSAs were used to advance the borehole incrementally until HSA refusal was encountered 

at 59 feet bgs. A continuous clay unit was observed to the terminal depth of the boring. Soil 

cuttings showed no signs of groundwater bearing zones, and the borehole remained dry after a 

day. Subsequent borings showed that the swelling clay encountered at AOI02-05 was present 

across the facility. Water-bearing units were generally not encountered during drilling. The clay 

encountered ranged in color between yellowish brown, gray, and dark greenish gray. These thick, 

impermeable clay layers with varying degree of silt and very fine sand were encountered to some 

degree in all borings during the SI and are consistent with the clay and sandy clay of the 

Mooresville Chalk of the Selma Group.

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

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

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

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

carbon (TOC) (USEPA Method 9060A), 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 duplicate (MSD) samples 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 
Site Inspection Report

Army Aviation Support Facility #1, Montgomery, Alabama

AECOM 5-4

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. Borings were installed in grass areas to avoid disturbing 

concrete or asphalt surfaces.

5.3 Temporary Well Installation and Groundwater Grab Sampling

During the SI, six temporary monitoring wells were installed within potential source areas. The 

locations of the wells are shown on Figure 5-1. Temporary wells were installed using a 

GeoProbe® 7822DT dual-tube sampling system. 

Once the borehole was advanced to the desired depth, wherever conditions allowed, 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.

Sufficient time was allowed for groundwater accumulation in the temporary wells before 

proceeding with collection of groundwater samples. Three of the temporary wells (AOI01-01, 

AOI02-02, and MGM-02) did not produce groundwater over the duration of the SI, so the wells 

were not sampled. A sufficient supply of groundwater for grab sampling was encountered at three

of the six temporary well locations (AOI02-01, AOI02-03, and AOI02-04). After the recharge 

period, groundwater samples were collected using a peristaltic pump with PFAS-free HDPE 

tubing. The temporary wells were attempted to be purged at a rate to reduce turbidity and draw 

down prior to sampling; however, this could not be achieved due to the limited availability and 

very slow recharge of groundwater. Based on the groundwater depths and widespread clay layer, 

the groundwater encountered appeared to be consistent with very shallow perched groundwater 

and not representative of deeper formational groundwater.

Water quality parameters (e.g., temperature, specific conductance, pH, dissolved oxygen [DO], 

and oxidation-reduction potential [ORP]) were measured using a water quality meter and recorded 

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

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

marker or pen. 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.

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/MSD samples 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.

Temporary wells were abandoned in accordance with the SI QAPP Addendum (AECOM, 2021) 

by removing the PVC and backfilling the hole with bentonite-cement grout. Upon completion of 

well abandonment, the ground surface at each location was patched to match existing 

surrounding conditions. Temporary wells were installed in grass areas to avoid disturbing concrete 

or asphalt.
Site Inspection Report

Army Aviation Support Facility #1, Montgomery, Alabama

AECOM 5-5

5.4 Surface Water 

In response to the evolved understanding of the CSM that suggests surface runoff may be the 

primary mechanism for hydrologic transport at the facility, surface water samples were collected 

from both AOIs. One sample was collected from Retention Area 2 located southeast of AOI 1, in 

the vicinity of soil boring location AOI01-04. The second sample was collected from Retention 

Area 1 at AOI 2, in the vicinity of soil boring location MGM-02. Surface water samples were 

collected as specified in Field Change Request Form FCR002, dated 21 January 2022 (Appendix 

B3). Sediment samples were not collected.

Surface water samples were collected at the top of the water column from a single point in the 

waterbody by using a peristaltic pump with PFAS-free HDPE tubing. Sampling was performed 

deliberately and methodically to minimize disturbance of bottom sediments and as quickly as 

possible to ensure a representative sample was collected. Additionally, a subsample of each 

surface water 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 surface water samples.

After collection of the surface water samples from each location, general water quality parameters 

(i.e., temperature, pH, conductivity, DO, and ORP) were collected with a water quality meter and 

recorded on the field sampling form (Appendix B2). The surface water sample locations are 

shown on Figure 5-1 and listed in Table 5-1. 

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

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

standard CoC procedures to the laboratory for analysis by LC/MS/MS compliant with QSM 5.1 

Table B-15. 

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

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

for the same parameters as the accompanying samples. A temperature blank was placed in each 

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

5.5 Synoptic Water Level Measurements

Due to the very limited and shallow perched groundwater conditions noted during the SI, a 

synoptic groundwater gauging event was not performed. Groundwater was only noted in three of 

the six temporary monitoring wells installed. Depths to water measured at these three locations 

ranged from 0.40 to 19.44 feet bgs; however, the groundwater measured deeper in the boring, 

within the clay, is suspected to have filled the borehole from above. Since the perched 

groundwater was not representative of actual potentiometric groundwater conditions, a

groundwater flow contour map was not generated. Perched groundwater level data are provided 

in Table 5-2.

5.6 Surveying

As stated in the Field Change Request Form FCR002, dated 21 January 2022 (Appendix B3),

and in Section 5.9, surveying of the temporary monitoring wells not completed due to the absence 

of representative groundwater conditions encountered.

5.7 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 
Site Inspection Report

Army Aviation Support Facility #1, Montgomery, Alabama

AECOM 5-6

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) generated during the SI activities were contained in three labeled, 55-

gallon Department of Transportation (DOT)-approved steel drums and stored south of the 

helicopter wash pad. 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 contained in one labeled, 55-gallon DOT-approved steel drum, and 

stored south of the helicopter wash pad, 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.

5.8 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.

5.9 Deviations from SI QAPP Addendum

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

documentation. The deviations are noted below and documented in Field Change Request Forms 

(Appendix B3): 

• DPT drilling and sampling refusal was observed in boring AOI02-05 at a depth of 20 feet 

bgs due to stiff, swelling clays encountered at 10 feet bgs and below. The clays expanded 

within the sampling cores to two times the length of the actual advanced interval (i.e., 5 feet 

core recovery over a 2.5 feet DPT run). Additionally, the expanding clays ruptured the 

acetate core liner in several instances, jamming the liner within the core barrel. DPT refusal 

was encountered at approximately 20 feet bgs. 

Groundwater was not observed prior to refusal; therefore, a decision was made to continue 

the borehole using the rig’s HSA capabilities; however, because discrete soil sampling is 

not possible without the use of the DPT tooling, soil samples for laboratory analysis could 

not be collected when using HSA. DPT sampling refusal at AOI02-05 was encountered 

below the maximum depth at which a screening level is established, 15 feet bgs for the 

industrial/commercial worker. Therefore, the surface soil sample and subsurface soil sample 

from the 13-15 feet bgs interval were successfully collected. The deep subsurface soil 

sample was not collected at AOI02-05 because groundwater was not encountered before 

refusal was met at 59 feet bgs. However, the results for the two sampled intervals (0-2 feet 

bgs and 13-15 feet bgs) are considered adequate in order to meet the data quality objectives 

for the SI. The Field Change Request Form noted similar changes may be necessary at 

subsequent boring locations if these conditions persisted.
Site Inspection Report

Army Aviation Support Facility #1, Montgomery, Alabama

AECOM 5-7

• At AOI02-05, soil cuttings showed no signs of groundwater bearing zones, and the borehole 

remained dry after a day; therefore, a groundwater sample could not be collected. 

Subsequent borings showed that the swelling clay encountered at AOI02-05 was present 

across the facility. At several locations, very shallow perched groundwater was available in 

enough volume that a grab sample was collected. The ability to collect these grab 

groundwater samples appeared to be dependent on the transmissivity of the first several 

feet of the subsurface. Groundwater samples were able to be collected at just three of the 

six planned locations: AOI02-01, AOI02-03, and AOI02-04. All DPT borings were advanced 

to refusal or at least 5 to 10 feet into the swelling clays to confirm the clay was present 

facility-wide. 

Additional deep boreholes were not attempted after AOI02-05 because of the homogeneity 

of the clay, concern of perforating the thick confining unit, and indications that groundwater 

was available only within the shallow subsurface. Infiltration appears to be limited, and 

transportation is likely controlled by topography, either by runoff or in the narrow 

transmissive zone. As a result of these findings and to account for possible data gaps, the 

following measures were taken after discussion with ARNG.

1) An additional DPT boring was completed at location MGM-02; this was considered 

the location most likely to provide an additional groundwater sample. Groundwater 

was not encountered, but two additional subsurface soil samples were collected.

2) An additional subsurface soil sample was collected at DPT boring AOI01-01 to add 

vertical data density at the potential release area.

3) Two additional surface soil samples were collected at AOI 1 to add data density at 

the potential release area.

4) Two surface water samples were collected to characterize runoff west and east of 

the AOIs.

5) Temporary wells were not surveyed. Near-surface, perched groundwater elevations 

were not considered adequate to generate a representative flow direction that would 

satisfy the data quality objectives.
Site Inspection Report

Army Aviation Support Facility #1, Montgomery, Alabama

AECOM 5-8

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Table 5-1

Site Inspection Samples by Medium

Site Inspection Report, AASF #1 RW Shepherd, Montgomery, Alabama

Sample Identification

Sample

Collection

Date/Time

Sample Depth

(feet bgs)

LC/MS/MS compliant withQSM 5.3 Table B-15TOC(USEPA Method 9060A)pH(USEPA Method 9045D)Grain Size (ASTM D-422)

Comments

AOI01-01-SB-00-02 1/20/2022 12:20 00-02 x x x

AOI01-01-SB-00-02-MS 1/20/2022 12:20 00-02 x MS/MSD

AOI01-01-SB-00-02-MSD 1/20/2022 12:20 00-02 x MS/MSD

AOI01-01-SB-05-07 1/21/2022 9:10 05-07 x

AOI01-01-SB-10-12 1/21/2022 9:20 10-12 x

AOI01-01-SB-13-15 1/21/2022 9:30 13-15 x

AOI01-01-SB-18-20 1/21/2022 9:40 18-20 x

AOI01-02-SB-00-02 1/18/2022 15:50 00-02 x

AOI01-02-SB-00-02-D 1/18/2022 15:50 00-02 x Duplicate

AOI01-03-SB-00-01 1/21/2022 9:05 00-01 x

AOI01-04-SB-00-01 1/21/2022 9:10 00-01 x

AOI02-01-SB-00-02 1/19/2022 16:20 00-02 x

AOI02-01-SB-00-02-D 1/19/2022 16:20 00-02 x Duplicate

AOI02-01-SB-08-10 1/20/2022 15:00 08-10 x

AOI02-01-SB-13-15 1/20/2022 15:15 13-15 x

AOI02-02-SB-00-02 1/19/2022 15:48 00-02 x

AOI02-02-SB-10-12 1/20/2022 16:20 10-12 x

AOI02-02-SB-13-15 1/20/2022 16:30 13-15 x

AOI02-03-SB-00-02 1/19/2022 13:45 00-02 x x x

AOI02-03-SB-00-02-D 1/19/2022 13:45 00-02 x x x Duplicate

AOI02-03-SB-00-02-MS 1/19/2022 13:45 00-02 x x MS/MSD

AOI02-03-SB-00-02-MSD 1/19/2022 13:45 00-02 x x MS/MSD

AOI02-03-SB-08-10 1/19/2022 14:45 08-10 x

AOI02-03-SB-13-15 1/19/2022 14:50 13-15 x

AOI02-04-SB-00-02 1/19/2022 15:00 00-02 x

AOI02-04-SB-08-10 1/19/2022 16:30 08-10 x

AOI02-04-SB-13-15 1/19/2022 17:00 13-15 x

AOI02-05-SB-00-02 1/18/2022 13:50 00-02 x

AOI02-05-SB-13-15 1/18/2022 14:32 13-15 x x

AOI02-06-SB-00-01 1/19/2022 9:50 00-01 x

AOI02-06-SB-00-01-MS 1/19/2022 9:50 00-01 x MS/MSD

AOI02-06-SB-00-01-MSD 1/19/2022 9:50 00-01 x MS/MSD

AOI02-07-SB-00-02 1/19/2022 8:50 00-02 x

MGM-01-SB-00-02 1/19/2022 11:15 00-02 x

MGM-02-SB-00-02 1/19/2022 10:30 00-02 x

MGM-02-SB-10-12 1/21/2022 12:49 10-12 x

MGM-02-SB-13-15 1/21/2022 12:50 13-15 x

Soil Samples

AECOM 5-9
Table 5-1

Site Inspection Samples by Medium

Site Inspection Report, AASF #1 RW Shepherd, Montgomery, Alabama

Sample Identification

Sample

Collection

Date/Time

Sample Depth

(feet bgs)

LC/MS/MS compliant withQSM 5.3 Table B-15TOC(USEPA Method 9060A)pH(USEPA Method 9045D)Grain Size (ASTM D-422)

Comments

AOI02-01-GW 1/21/2022 11:52 NA x

AOI02-03-GW 1/20/2022 10:52 NA x

AOI02-03-GW-D 1/20/2022 10:52 NA x Duplicate

AOI02-03-GW-MS 1/20/2022 10:52 NA x MS/MSD

AOI02-03-GW-MSD 1/20/2022 10:52 NA x MS/MSD

AOI02-04-GW 1/21/2022 12:30 NA x

MGM-03-SW 1/21/2022 15:03 NA x

MGM-04-SW 1/21/2022 15:05 NA x

MGM-04-SW-D 1/21/2022 15:05 NA x Duplicate

MGM-04-SW-MS 1/21/2022 15:05 NA x MS/MSD

MGM-04-SW-MSD 1/21/2022 15:05 NA x MS/MSD

MGM-FRB-01 1/20/2022 10:00 NA x FRB

MGM-ERB-01 1/19/2022 9:15 NA x ERB

MGM-ERB-02 1/20/2022 9:20 NA x ERB

MGM-ERB-03 1/20/2022 9:30 NA x ERB

MGM-DECON-01 11/16/2021 14:55 NA x DECON

MGM-DECON-02 11/16/2021 14:45 NA x DECON

MGM-DECON-03 1/21/2022 11:00 NA x DECON

Notes:

ASTM = American Society for Testing and Materials

bgs = below ground surface

ERB = equipment rinsate blank

FRB = field reagent blank

LC/MS/MS = Liquid Chromatography Mass Spectrometry

MS/MSD = matrix spike/ matrix spike duplicate

QSM = Quality Systems Manual

TOC = total organic carbon

USEPA = United States Environmental Protection Agency

Quality Control Samples

Groundwater Samples

Surface Water Samples

AECOM 5-10
Table 5-2

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

Site Inspection Report, AASF #1 RW Shepherd, Montgomery, Alabama

Area of

Interest

Boring

Location

Soil Boring

Depth

(feet bgs)

Temporary Well

Screen Interval

(feet bgs)

Depth to

Water

(feet btoc)

Depth to

Water

(feet bgs)

AOI02-01 20 15-20 11.25 10.85

AOI02-03 27.5 22-27 1.00 0.40

AOI02-04 25 20-25 19.94 19.44

Notes:

bgs = below ground surface

btoc = below top of casing

Groundwater levels appeared indicative of perched groundwater and were not considered adequate to generate a representative flow direction that would satisfy the data quality objectives.

Therefore, the temporary well locations were not surveyed. Depth to Water (bgs) is calculated from field-measured well casing stick up height

2

AECOM 5-11
Site Inspection Report

Army Aviation Support Facility #1, Montgomery, Alabama

AECOM 5-12

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AOI 2

AOI 1

AOI01-01

AOI01-02

AOI02-01

AOI02-02

AOI02-03

AOI02-04

AOI02-05

AOI02-06

AOI02-07

MGM-01

MGM-02

AOI01-03

AOI01-04

MGM-04

MGM-03

Retention

Area 2

Retention

Area 1

Legend

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Area of Interest

Facility Boundary

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Intermittent Creek

Surface Water Flow Direction

Inferred Groundwater Flow Direction

Site Inspection Sample Locations

Figure 5-1

CLIENT

REVISED

SCALE

10/24/2022 MS

MC

10/24/2022

10/24/2022

ARNG

GIS BY

CHK BY

PROJECT Site Inspection at AASF #1 R W Shepherd Hope Hull, AL

PM CM 10/24/2022

1:3,000 ­ 12420 Milestone Center Drive

Germantown, MD 20876

0 125 250 500

Feet

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

AOI 2

AOI 1

AECOM 5-13
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Army Aviation Support Facility #1, Montgomery, Alabama

AECOM 5-14

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Site Inspection Report

Army Aviation Support Facility #1, Montgomery, 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 6.4. Table 6-2 through Table 6-5 present results in soil, groundwater, and surface

water 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 #1, Montgomery, 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 surface water for AOI 1: Hangar Fire 

Suppression System, Mechanical Room, and Hazardous Waste Storage Room. Groundwater 

was not encountered within AOI 1 during the SI. The soil and surface water results are 

summarized on Table 6-2, Table 6-3, and Table 6-5. Soil and surface water results are presented 

on Figure 6-1 through Figure 6-5 and Figure 6-8 through Figure 6-9. SLs are available for soil 

but not for surface water.

6.3.1 AOI 1 Soil Analytical Results

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

through AOI01-04 and MGM-01. Soil was also sampled from the shallow subsurface (between 5 

to 15 feet bgs) from three intervals at boring location AOI01-01. Deep subsurface soil samples 

were not collected. AOI01-01, AOI01-03, AOI01-04, and MGM-01 were located to the east and 

southeast of the Mechanical Room, and AOI01-02 was located to the north of the Hangar. Figure 

6-1 through Figure 6-5 present the ranges of detections in soil. Table 6-2 and Table 6-3

summarize the soil results.

At AOI 1, PFOA, PFOS, and PFHxS exceeded the SLs in surface soil, and PFOS exceeded the 

SL in shallow subsurface soil. PFOA and PFHxS did not exceed the shallow subsurface soil SLs. 

PFBS and PFNA were below the SLs in both surface and shallow subsurface soil. 

In surface soil, PFOA, PFOS, PFBS, and PFHxS were detected at all five locations. PFNA was 

detected at two locations. A summary of detections for each compound is provided below:

• PFOA concentrations ranged from 0.299 J micrograms per kilogram (μg/kg) to 165

μg/kg. PFOA exceeded the 19 μg/kg SL at two locations: AOI01-01 and AOI01-04.

• PFOS concentrations ranged from 3.68 μg/kg to 10,900 J μg/kg. PFOS exceeded the

13 μg/kg SL at four locations: AOI01-01, AOI01-03, AOI01-04, and MGM-01.

• The maximum PFBS concentration was 795 μg/kg, below the 1,900 μg/kg SL.

• PFHxS concentrations ranged from 6.24 μg/kg to 3,840 μg/kg. PFHxS exceeded the 

130 μg/kg SL at two locations: AOI01-01 and AOI01-04.

• The maximum PFNA concentration was 0.051 J μg/kg, below the 19 μg/kg SL.
Site Inspection Report

Army Aviation Support Facility #1, Montgomery, Alabama

AECOM 6-3

Shallow subsurface soil was only sampled at AOI01-01. PFOS was the only compound that 

exceeded the SL in shallow subsurface soil. A summary of detections is provided here: 

• The maximum PFOA concentration was 11.6 μg/kg, below the 250 μg/kg SL.

• PFOS concentrations ranged from 0.263 J μg/kg to 499 μg/kg. PFOS exceeded the 160 

μg/kg SL at the 5 to 7 feet bgs depth interval.

• The maximum PFBS concentration was 29.3 μg/kg, below the 25,000 μg/kg SL.

• The maximum PFHxS concentration was 232 μg/kg, below the 1,600 μg/kg SL.

• The maximum PFNA concentration was 0.025 μg/kg, below the 250 μg/kg SL.

6.3.2 AOI 1 Surface Water Analytical Results

One surface water sample (MGM-03) was collected at AOI 1. The sample was obtained from 

Retention Area 2, located south and hydraulically downgradient of the Mechanical Room. Figure 

6-8 and Figure 6-9 present the ranges of detections in surface water. Table 6-5 summarizes the 

surface water results.

PFOA, PFOS, PFBS, and PFHxS were detected at MGM-03. PFNA was not detected. PFOA was 

detected at a concentration of 1,500 nanograms per liter (ng/L). PFOS was detected at a 

concentration of 27,500 ng/L. PFBS was detected at a concentration of 6,410 ng/L. PFHxS was 

detected at a concentration of 34,500 ng/L. 

6.3.3 AOI 1 Conclusions

Based on the results of the SI, PFOA, PFOS, and PFHxS were detected in soil at AOI 1 above 

their SLs. PFBS and PFNA were detected in soil below their SLs. PFOA, PFOS, PFBS, and 

PFHxS were detected in surface water. PFNA was not detected in surface water. There are no 

established SLs for surface water; therefore, these results are presented for informational 

purposes only. No groundwater samples were collected from AOI 1 during the SI. Based on the 

exceedances of the SLs in soil, further evaluation at AOI 1 is warranted.

6.4 AOI 2

This section presents the analytical results for soil, groundwater, and surface water for AOI 2: 

Flight Ramp and Wash Rack. The results in soil, groundwater, and surface water are summarized 

on Table 6-2 through Table 6-5. Soil, groundwater, and surface water results are presented on 

Figure 6-1 through Figure 6-9. SLs are available for soil but not for surface water.

6.4.1 AOI 2 Soil Analytical Results

Surface soil was sampled from 0 to 2 feet bgs at boring locations AOI02-01 through AOI02-07

and MGM-02. Soil was also sampled from the shallow subsurface (between 8 and 15 feet bgs) at 

multiple intervals at AOI02-01 through AOI01-05, as well as MGM-02. Deep subsurface soil 

samples were not collected. AOI02-01 was located to the east of the Wash Rack, and AOI02-02 

through AOI02-07 and MGM-02 encircled the Flight Ramp. Figure 6-1 through Figure 6-5 present 

the ranges of detections in soil. Table 6-2 and Table 6-3 summarize the soil results.

At AOI 2, PFOS exceeded the SL in surface soil. PFOS was below the SL in shallow subsurface 

soil. PFOA, PFBS, PFHxS, and PFNA were below their SLs in both surface and shallow 

subsurface soil. 
Site Inspection Report

Army Aviation Support Facility #1, Montgomery, Alabama

AECOM 6-4

A summary of detections for each compound in surface soil is provided here:

• PFOA was detected at four locations and at a maximum concentration of 0.415 J μg/kg, 

below the 19 μg/kg SL.

• PFOS was detected at all locations. Concentrations ranged from 0.073 J μg/kg to 16.8 

J μg/kg. PFOS exceeded the 13 μg/kg SL at one location, AOI02-01.

• PFBS was detected at seven locations and at a maximum concentration of 0.289 J

μg/kg, below the 1,900 μg/kg SL.

• PFHxS was detected at seven locations and at a maximum concentration of 2.96 μg/kg, 

below the 130 μg/kg SL.

• PFNA was detected at three locations and at a maximum concentration of 0.214 J 

μg/kg, below the 19 μg/kg SL.

PFOA, PFOS, PFBS, PFHxS, and PFNA concentrations were detected below the SLs in shallow 

subsurface soil. A summary of the detections for each compound is provided here:

• PFOA and PFNA were not detected in any shallow subsurface soil sample.

• PFOS was detected in three samples and at a maximum concentration of 0.487 J μg/kg, 

below the 160 μg/kg SL.

• PFBS was detected in one sample at a concentration of 0.037 J μg/kg, below the 25,000 

μg/kg SL.

• PFHxS was detected in two samples and at a maximum concentration of 0.097 J μg/kg, 

below the 1,600 μg/kg SL.

6.4.2 AOI 2 Groundwater Analytical Results

Groundwater was sampled from AOI02-01, AOI02-03, and AOI02-04. AOI02-01 was located to 

the east of the Wash Rack, and AOI02-03 and AOI02-04 were located to the west and north of 

the Flight Ramp, respectively. Figure 6-6 and Figure 6-7 present the ranges of detections in 

groundwater. Table 6-4 summarizes the groundwater results. 

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

SLs. PFBS was detected in groundwater at concentrations below the SL.

PFOA, PFOS, PFBS, and PFHxS were detected in all three wells. A summary of detections in 

groundwater is provided here:

• PFOA concentrations ranged from 3.85 J ng/L to 55.9 ng/L. PFOA exceeded the 6 ng/L 

SL at two locations, AOI02-01 and AOI02-03.

• PFOS concentrations ranged from 8.97 ng/L to 499 ng/L. PFOS exceeded the 4 ng/L 

SL at all three locations: AOI02-01, AOI02-03, and AOI02-04.

• The maximum PFBS concentration was 111 ng/L, below the 601 ng/L SL.

• PFHxS concentrations ranged from 17.0 ng/L to 974 ng/L. PFHxS exceeded the 39 ng/L 

SL at two locations, AOI02-01 and AOI02-03.

• PFNA was detected only at AOI02-01, above the 6 ng/L SL, at a concentration of 13.3 

ng/L. 
Site Inspection Report

Army Aviation Support Facility #1, Montgomery, Alabama

AECOM 6-5

6.4.3 AOI 2 Surface Water Analytical Results 

One surface water sample (MGM-04) was collected at AOI 2. The sample was obtained from 

Retention Area 2, located southwest and hydraulically downgradient of the Flight Ramp. PFOA, 

PFBS, and PFNA were not detected at MGM-04. PFOS was detected at a concentration of 3.89 

J ng/L. PFHxS was detected at a concentration of 1.63 ng/L. Figure 6-8 and Figure 6-9 present 

the ranges of detections in surface water. Table 6-5 summarizes the surface water results. 

6.4.4 AOI 2 Conclusions

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

PFBS, PFHxS, and PFNA were detected in soil at concentrations below their SLs. PFOA, PFOS, 

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

detected in groundwater at concentrations below the SL. PFOS and PFHxS were also detected 

in surface water. There are no established SLs for surface water; therefore, these results are 

presented for informational purposes only. Based on the exceedances of the SLs in soil and 

groundwater, further evaluation at AOI 2 is warranted.
Site Inspection Report

Army Aviation Support Facility #1, Montgomery, Alabama

AECOM 6-6

THIS PAGE INTENTIONALLY BLANK
Table 6-2

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

Site Inspection Report, AASF #1 R W Shepherd Hope Hull

Analyte OSD Screening 

Level a

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

PFBS 1900 216 0.280 J 0.293 J 5.81 795 4.39 0.053 J 0.085 J ND 

PFHxS 130 1890 6.24 7.11 123 3840 31.7 1.83 2.68 0.078 

PFNA 19 ND U 0.035 J 0.051 J ND U ND U 0.026 J 0.159 J 0.214 J 0.031 PFOA 19 148 0.299 J 0.387 J 3.89 J 165 1.26 J 0.213 J 0.415 J ND 

PFOS 13 10900 J 3.68 4.82 486 8330 358 11.4 J 16.8 J 0.601 

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

D duplicate

Notes DL detection limitND = Analyte not detected above the LOD. LOD values are presented in Appendix F. ft feet

HQ hazard quotientID identificationLCMSMS liquid chromatography with tandem LOD limit of detectionMGM MontgomeryND 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

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 AOI02

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

AOI02-01-SB-00-02-D

01/19/2022

0-2 ft

AOI

MGM-01-SB-00-02

01/19/2022

0-2 ft

AOI02-01-SB-00-02

01/19/2022

0-2 ft

AOI01-03-SB-00-01

01/21/2022

0-1 ft

AOI01-04-SB-00-01

01/21/2022

0-1 ft

AOI01-02-SB-00-02

01/18/2022

0-2 ft

AOI01-02-SB-00-02-D

01/18/2022

0-2 ft

Area of Interest

Sample ID

Sample Date

Depth

AOI01-01-SB-00-02

01/20/2022

0-2 ft

AECOM 
Table 6-2

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

Site Inspection Report, AASF #1 R W Shepherd Hope Hull

Analyte OSD Screening 

Level a

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

PFBS 1900 0.289 J ND U 0.028 J 0.048 J 0.044 J 0.110 JPFHxS 130 2.96 ND U 0.061 J 0.066 J 0.230 J 0.813 JPFNA 19 ND U ND U ND U ND U ND U 0.090 JPFOA 19 0.181 J ND U ND U ND U ND U 0.359 JPFOS 13 1.11 0.080 J 0.073 J 0.785 J 0.595 J 5.66

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

D duplicate

Notes DL detection limitND = Analyte not detected above the LOD. LOD values are presented in Appendix F. ft feet

HQ hazard quotientID identificationLCMSMS liquid chromatography with tandem LOD limit of detectionMGM MontgomeryND 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

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

AOI02

MGM-02-SB-00-02

01/19/2022

0-2 ft

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

AOI02-06-SB-00-01

01/19/2022

0-1 ft

AOI02-07-SB-00-02

01/19/2022

0-2 ft

AOI02-04-SB-00-02

01/19/2022

0-2 ft

AOI02-05-SB-00-02

01/18/2022

0-2 ft

Area of Interest

Sample ID

Sample Date

Depth

AOI02-03-SB-00-02-D

01/19/2022

0-2 ft

AECOM 
Table 6-3

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

Site Inspection Report, AASF #1 R W Shepherd Hope Hull

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Res

PFBS 25000 29.3 0.287 J ND U 0.031 J 0.037 J ND U ND U ND U ND 

PFHxS 1600 232 2.48 0.063 J ND U 0.097 J ND U ND U ND U ND PFNA 250 0.025 J ND U ND U ND U ND U ND U ND U ND U ND PFOA 250 11.6 0.125 J ND U ND U ND U ND U ND U ND U ND PFOS 160 499 4.34 0.263 J 0.115 J 0.115 J ND U 0.152 J 0.076 J ND 

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

D duplicate

Notes DL detection limitND = Analyte not detected above the LOD. LOD values are presented in Appendix F. ft feet

HQ hazard quotientID identificationLCMSMS liquid chromatography with tandem LOD limit of detectionMGM MontgomeryND 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

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

Area of Interest AOI01 AOI02

Sample ID

Sample Date

Depth

AOI01-01-SB-05-07

01/21/2022

5-7 ft

AOI02-01-SB-08-10

01/20/2022

8-10 ft

AOI01-01-SB-10-12

01/21/2022

10-12 ft

AOI01-01-SB-13-15

01/21/2022

13-15 ft

AOI02-01-SB-13-15

01/20/2022

13-15 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.

AOI02-03-SB-08-10

01/19/2022

8-10 ft

AOI0

AOI02-02-10-12

01/20/2022

10-12 ft

AOI02-02-13-15

01/20/2022

13-15 ft

AECOM 
Table 6-3

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

Site Inspection Report, AASF #1 R W Shepherd Hope Hull

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual

PFBS 25000 ND U ND U ND U ND UPFHxS 1600 ND U ND U 0.091 J 0.088 JPFNA 250 ND U ND U ND U ND UPFOA 250 ND U ND U ND U ND UPFOS 160 ND U ND U 0.419 J 0.487 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 FacilityU = The analyte was not detected at a level greater than or equal to the adjusted DL AOI Area of Interest

D duplicate

Notes DL detection limitND = Analyte not detected above the LOD. LOD values are presented in Appendix F. ft feet

HQ hazard quotientID identificationLCMSMS liquid chromatography with tandem LOD limit of detectionMGM MontgomeryND 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

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.

MGM-02-SB-13-15

01/21/2022

13-15 ft

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

AOI02-05-SB-13-15

01/18/2022

13-15 ft

MGM-02-SB-10-12

01/21/2022

10-12 ft

Sample ID

Sample Date

Depth

AOI02-04-SB-13-15

01/19/2022

13-15 ft

Area of Interest AOI02

AECOM 
Table 6-4

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

Site Inspection Report, AASF #1 R W Shepherd Hope Hull

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual

PFBS 601 111 72.3 J- 74.4 J- 5.07PFHxS 39 974 177 J- 166 J- 17.0

PFNA 6 13.3 ND U ND U ND U

PFOA 6 55.9 19.4 18.0 3.85 J

PFOS 4 499 8.97 7.47 129

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 D duplicate

DL detection limit

Notes GW groundwaterND = 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 qualifierUSEPA United States Environmental Protecng/l nanogram per liter

AOI02-04-GW

01/21/2022

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.

AOI02

AOI02-03-GW

01/20/2022

AOI02-03-GW-D

01/20/2022

Area of Interest

Sample ID

Sample Date

AOI02-01-GW

01/21/2022

AECOM 
Table 6-5

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

Site Inspection Report, AASF #1 R W Shepherd Hope Hull

Area of Interest

Sample ID

Sample Date

Analyte Result Qual Result Qual Result Qual

PFBS 6410 ND U ND U

PFHxS 34500 1.63 J ND UJPFNA ND U ND U ND UPFOA 1500 ND U ND UPFOS 27500 3.89 J 2.35 J

J = Estimated concentrationU = The analyte was not detected at a level greater than or equal to the adjusted DL Chemical AbbreviationsUJ = 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. PFBS perfluorobutanesulfonic acid

PFHxS perfluorohexanesulfonic acid

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

PFOS perfluorooctanesulfonic acidAcronyms and Abbreviations

AASF Army Aviation Support FacilityAOI Area of InterestD duplicateDL detection limitID identificationLCMSMS liquid chromatography with tandem mass LOD limit of detectionMGM MontgomeryND analyte not detected above the LODQSM Quality Systems ManualQual interpreted qualifierng/l nanogram per literSW surface water

MGM-04-SW-D

01/21/2022

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

AOI01 AOI02

MGM-03-SW

01/21/2022

MGM-04-SW

01/21/2022

AECOM 
AOI01-01

AOI01-02

AOI02-01

AOI02-02

AOI02-03

AOI02-04

AOI02-05

AOI02-06

AOI02-07

MGM-01

MGM-02

AOI01-03

AOI01-04

AOI01-01

AOI02-02

AOI02-03

AOI02-04

MGM-02

AOI01-01

AOI02-01

AOI02-02

AOI02-03

AOI02-04

AOI02-05

MGM-02

12420 Milestone Center Drive

Germantown, MD 20876 Figure 6-1

PFOA Detections in Soil

8/11/2022

8/11/2022

MS 8/11/2022

VG

CM

GIS BY

CHK BY

PM

8/11/2022

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection at AASF #1 R W Shepherd Hope Hull, AL

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

the GIS User Community

1:3,960

Shallow

Intermediate

Deep

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

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

0 165 330 660

­

Feet

Facility Boundary

Intermittent Creek

Inferred Groundwater Flow Direction

PFOA Results (μg/Kg)

ND

>ND - 19

>19 - 250

>250 - 2,500

>2,500

AECOM 6-13
AOI01-01

AOI01-02

AOI02-01

AOI02-02

AOI02-03

AOI02-04

AOI02-05

AOI02-06

AOI02-07

MGM-01

MGM-02

AOI01-03

AOI01-04

AOI01-01

AOI02-02

AOI02-03

AOI02-04

MGM-02

AOI01-01

AOI02-01

AOI02-02

AOI02-03

AOI02-04

AOI02-05

MGM-02

12420 Milestone Center Drive

Germantown, MD 20876 Figure 6-2

PFOS Detections in Soil

8/11/2022

8/11/2022

MS 8/11/2022

VG

CM

GIS BY

CHK BY

PM

8/11/2022

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection at AASF #1 R W Shepherd Hope Hull, AL

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

the GIS User Community

1:3,960

Shallow

Intermediate

Deep

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

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

Facility Boundary

Intermittent Creek

Inferred Groundwater Flow Direction

PFOS Results (μg/Kg)

ND

>ND - 13

>13 - 160

>160 - 1,600

>1,600 0 165 330 660

­

Feet

AECOM 6-14
AOI01-01

AOI01-02

AOI02-01

AOI02-02

AOI02-03

AOI02-04

AOI02-05

AOI02-06

AOI02-07

MGM-01

MGM-02

AOI01-03

AOI01-04

AOI01-01

AOI02-02

AOI02-03

AOI02-04

MGM-02

AOI01-01

AOI02-01

AOI02-02

AOI02-03

AOI02-04

AOI02-05

MGM-02

12420 Milestone Center Drive

Germantown, MD 20876 Figure 6-3

PFBS Detections in Soil

8/11/2022

8/11/2022

MS 8/11/2022

VG

CM

GIS BY

CHK BY

PM

8/11/2022

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection at AASF #1 R W Shepherd Hope Hull, AL

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

the GIS User Community

1:3,960

Shallow

Intermediate

Deep

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

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

Facility Boundary

Intermittent Creek

Inferred Groundwater Flow Direction

PFBS Results (μg/Kg)

ND

>ND - 10

>10 - 1,900

>1,900 - 25,000

>25,000

0 165 330 660

­

Feet

AECOM 6-15
AOI01-01

AOI01-02

AOI02-01

AOI02-02

AOI02-03

AOI02-04

AOI02-05

AOI02-06

AOI02-07

MGM-01

MGM-02

AOI01-03

AOI01-04

AOI01-01

AOI02-02

AOI02-03

AOI02-04

MGM-02

AOI01-01

AOI02-01

AOI02-02

AOI02-03

AOI02-04

AOI02-05

MGM-02

12420 Milestone Center Drive

Germantown, MD 20876 Figure 6-4

PFHxS Detections in Soil

8/11/2022

8/11/2022

MS 8/11/2022

VG

CM

GIS BY

CHK BY

PM

8/11/2022

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection at AASF #1 R W Shepherd Hope Hull, AL

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

the GIS User Community

1:3,960

Shallow

Intermediate

Deep

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

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

0 165 330 660

­

Feet

Facility Boundary

Intermittent Creek

Inferred Groundwater Flow Direction

PFHxS Results (μg/Kg)

ND

>ND - 10

>10 - 130

>130 - 1,600

>1,600

AECOM 6-16
AOI01-01

AOI01-02

AOI02-01

AOI02-02

AOI02-03

AOI02-04

AOI02-05

AOI02-06

AOI02-07

MGM-01

MGM-02

AOI01-03

AOI01-04

AOI01-01

AOI02-02

AOI02-03

AOI02-04

MGM-02

AOI01-01

AOI02-01

AOI02-02

AOI02-03

AOI02-04

AOI02-05

MGM-02

12420 Milestone Center Drive

Germantown, MD 20876 Figure 6-5

PFNA Detections in Soil

8/11/2022

8/11/2022

MS 8/11/2022

VG

CM

GIS BY

CHK BY

PM

8/11/2022

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection at AASF #1 R W Shepherd Hope Hull, AL

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

the GIS User Community

1:3,960

Shallow

Intermediate

Deep

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

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

0 165 330 660

­

Feet

Facility Boundary

Intermittent Creek

Inferred Groundwater Flow Direction

PFNA Results (μg/Kg)

ND

>ND - 19

>19 - 250

>250 - 2,500

>2,500

AECOM 6-17
Retention

Area 2

Retention

Area 1

AOI02-01

AOI02-03

AOI02-04

Legend

Facility Boundary

Retention Area Boundary

Intermittent Creek

Inferred Groundwater Flow Direction

Retention

Area 2

Retention

Area 1

AOI02-01

AOI02-03

AOI02-04

Retention

Area 2

Retention

Area 1

AOI02-01

AOI02-03

AOI02-04

12420 Milestone Center Drive

Germantown, MD 20876 Figure 6-6

PFOA, PFOS, and PFBS Detections

 in Groundwater

10/5/2022

10/5/2022

MS 10/5/2022

VG

CM

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PM

10/5/2022

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection at AASF #1 R W Shepherd Hope Hull, AL

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

the GIS User Community

1:4,200

PFOA

PFOS

PFBS

PFOA Results (ng/L)

ND

>ND - 6

>6 - 40

>40 - 70

>70

PFOS Results (ng/L)

ND

>ND - 4

>4 - 40

>40 - 70

>70

PFBS Results (ng/L)

ND

>ND - 100

>100 - 601

>601 - 2,000

>2,000

0 175 350 700

­

Feet

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

AECOM 6-18
Retention

Area 2

Retention

Area 1

AOI02-01

AOI02-03

AOI02-04

Legend

Facility Boundary

Retention Area Boundary

Intermittent Creek

Inferred Groundwater Flow Direction

Retention

Area 2

Retention

Area 1

AOI02-01

AOI02-03

AOI02-04

12420 Milestone Center Drive

Germantown, MD 20876 Figure 6-7

PFHxS and PFNA Detections

 in Groundwater

8/11/2022

8/11/2022

MS 8/11/2022

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REVISED

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Site Inspection at AASF #1 R W Shepherd Hope Hull, AL

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

the GIS User Community

1:3,000

PFNA

PFHxS

PFNA Results (ng/L)

ND

>ND - 6

>6 - 100

>100 - 1,000

>1,000

PFHxS Results (ng/L)

ND

>ND - 39

>39 - 100

>100 - 1,000

>1,000

0 125 250 500

­

Feet

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

AECOM 6-19
Retention

Area 2

Retention

Area 1

MGM-04

MGM-03

Legend

Facility Boundary

Retention Area Boundary

Intermittent Creek

Surface Water Flow Direction

Retention

Area 2

Retention

Area 1

MGM-04

MGM-03

Retention

Area 2

Retention

Area 1

MGM-04

MGM-03

12420 Milestone Center Drive

Germantown, MD 20876 Figure 6-8

PFOA, PFOS, and PFBS Detections

 in Surface Water

10/24/2022

10/24/2022

MS 10/24/2022

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the GIS User Community

1:4,200

PFOA

PFOS

PFBS

PFOA Results (ng/L)

ND

>ND - 6

>6 - 40

>40 - 70

>70

PFOS Results (ng/L)

ND

>ND - 4

>4 - 40

>40 - 70

>70

PFBS Results (ng/L)

ND

>ND - 100

>100 - 601

>601 - 1,000

>1,000

0 175 350 700

­

Feet

AECOM 6-20
Retention

Area 2

Retention

Area 1

MGM-04

MGM-03

Legend

Facility Boundary

Retention Area Boundary

Intermittent Creek

Surface Water Flow Direction

Retention

Area 2

Retention

Area 1

MGM-04

MGM-03

12420 Milestone Center Drive

Germantown, MD 20876 Figure 6-9

PFHxS and PFNA Detections

 in Surface Water

10/24/2022

10/24/2022

MS 10/24/2022

VG

CM

GIS BY

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10/24/2022

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Site Inspection at AASF #1 R W Shepherd Hope Hull, AL

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

the GIS User Community

1:3,000

PFNA

PFHxS

PFNA Results (ng/L)

ND

>ND - 6

>6 - 100

>100 - 1,000

>1,000

PFHxS Results (ng/L)

ND

>ND - 39

>39 - 100

>100 - 1,000

>1,000

0 125 250 500

­

Feet

AECOM 6-21
Site Inspection Report

Army Aviation Support Facility #1, Montgomery, Alabama

AECOM 6-22

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Site Inspection Report

Army Aviation Support Facility #1, Montgomery, 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 an 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, 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 and AOI 2 based on the aforementioned 

criteria.

7.1.1 AOI 1

AOI 1 consists of three potential release areas. The AASF #1 hangar contains an overhead fire 

suppression system supplied by two 800-gallon AFFF concentration tanks located in the 

mechanical room, as well as smaller stationary AFFF floor tanks on the hangar floor. Between 

2006 to 2009, an unknown quantity of AFFF was reportedly released to the unpaved, grassy area 

south of the mechanical room. A 5-gallon jug of 3% AFFF concentrate was observed in the 
Site Inspection Report

Army Aviation Support Facility #1, Montgomery, Alabama

AECOM 7-2

hazardous waste storage room during the PA site visit. Floor and trench drains inside the hangar 

and mechanical room convey to the OWS and then the sanitary sewer. Grassy areas are present 

adjacent to the hangar doors and mechanical room. 

At AOI 1, PFOA, PFOS, and PFHxS were detected in surface soil above their SLs. Site workers

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

inhalation of dust; therefore, the surface soil exposure pathways for those receptors are 

considered potentially complete. PFOS was detected in subsurface soil and exceeded the SL.

Future construction workers could contact constituents in subsurface soil via incidental ingestion; 

therefore, the subsurface soil exposure pathway for this receptor is considered potentially 

complete. The facility is gated and over 500 feet from the nearest residential structures; therefore, 

the surface soil pathways for the residential and trespasser/recreational user receptors are 

considered incomplete. The CSM for AOI 1 is presented on Figure 7-1. 

7.1.2 AOI 2

AOI 2 consists of two potential release areas. Mobile AFFF Tri-MaxTM 30 extinguisher units were 

staged along the flight ramp from 2001 to 2017 and may have been emptied before being removed 

from the facility. The Tri-MaxTM 30 units may have also been used at the wash rack, located south 

of the hangar building. Grassy areas are present adjacent to the flight ramp and wash rack.

At AOI 2, PFOS was detected in surface soil in the vicinity of the Wash Rack at concentrations 

above the residential SL. PFOA, PFOS, PFBS, PFHxS, and PFNA were detected in subsurface 

soil below their industrial/commercial composite worker SLs. Site workers and construction 

workers could contact constituents in surface soil via incidental ingestion and inhalation of dust; 

therefore, the surface soil exposure pathways for those receptors are considered potentially 

complete. Active construction was observed at the Flight Ramp during the SI. Current and future 

construction workers could contact constituents in subsurface soil via incidental ingestion;

therefore, the shallow subsurface soil exposure pathway for this receptor is considered potentially 

complete. The facility is gated and over 500 feet from the nearest residential structures; therefore, 

the surface soil exposure pathways for the residential and trespasser/recreational user receptors 

are considered incomplete. 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

Groundwater was not encountered at AOI 1 during the SI; therefore, groundwater samples were 

not collected, and an evaluation based on AOI-specific data cannot be made in this report. 

However, based on proximity, the groundwater exposure pathway at AOI 1 can be reasonably 

assumed to be similar to that at AOI 2 discussed below. The human receptors for shallow 

groundwater are shown as incomplete on Figure 7-1 at this time.

7.2.2 AOI 2

At AOI 2, PFOA, PFOS, PFHxS, and PFNA were detected in groundwater at concentrations above 

their SLs. Depths to water measured during the SI at the three well locations ranged from 0.40 to 

19.44 feet bgs. Based on the groundwater depths and widespread clay layer observed during the 

SI, the groundwater encountered appeared to be consistent with very shallow perched 

groundwater.
Site Inspection Report

Army Aviation Support Facility #1, Montgomery, Alabama

AECOM 7-3

Both site workers and construction workers could come in contact with constituents in the shallow 

perched groundwater via incidental ingestion; therefore, the groundwater exposure pathway for 

this receptor is considered potentially complete. No known public supply wells or private drinking 

water wells exist at the facility or the surrounding area within a 1-mile radius. It is possible that 

unregistered, private, domestic wells exist downgradient of AOI 2, which may result in potential 

exposure via ingestion of groundwater. Due to the absence of known private wells and public 

water system wells within a 1-mile radius of the facility, the pathway for exposure to off-facility 

residents and recreational users via ingestion of groundwater is considered incomplete. The CSM 

for AOI 2 is presented on Figure 7-2. 

7.3 Surface Water and Sediment Exposure Pathway

The SI results in surface water were used to determine whether a potentially complete pathway 

exists between the source and potential receptors at each AOI based on the aforementioned 

criteria. Sediment samples were not collected; therefore, data from the SI results in soil,

groundwater, and surface water, 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. These compounds are water soluble and can migrate 

readily from soil to surface water via leaching and run-off. Additionally, based on the very shallow, 

perched groundwater conditions and swelling clay observed during the SI, surface water runoff 

appears to be the primary mechanism of hydrologic transport at the facility.

7.3.1 AOI 1

PFOA, PFOS, PFBS, and PFHxS were detected in a surface water sample obtained from 

Retention Area 2, located downslope of AOI 1. Additionally, PFOA, PFOS, and PFHxS were 

detected in surface soil at AOI 1. Therefore, based on the known compounds within the surface 

water and soluble properties of these compounds, the surface water and sediment ingestion 

exposure pathway for site workers and future construction workers is considered potentially 

complete.

Based on site observations, Retention Area 2 appears to be impounded and does not drain offfacility. As discussed in Section 2.2.3, no outflow or surface water bodies flowing from AOI 1 were 

identified. Instead, Retention Area 2 is the low point within the southeast corner of the facility. Due 

to the absence of surface water features allowing drainage from Retention Area 2 to off-facility 

receptors, the surface water and sediment ingestion exposure pathway for off-facility residents 

and recreational users is considered incomplete. The CSM for AOI 1 is presented on Figure 7-1.

7.3.2 AOI 2

PFOS and PFHxS were detected in a surface water sample obtained from Retention Area 1, 

located southwest and hydraulically downgradient of the Flight Ramp. Additionally, at AOI 2, 

PFOA, PFOS, PFBS, PFHxS, and PFNA was detected in surface soil, and PFOA, PFOS, PFHxS, 

and PFNA were detected in shallow groundwater. Therefore, based on the known compounds 

within the surface water and soluble properties of PFAS, the surface water and sediment ingestion 

exposure pathway for site workers, construction workers, or recreational users is considered 

potentially complete.

Surface water in the vicinity of AOI 2 may drain toward Retention Area 1, located west-southwest 

of the flight ramp. During highwater conditions, Retention Area 1 may drain southward via an 

intermittent stream. The stream then drains to Pintlala Creek, located 2.5 miles southwest of the 

facility. Pintlala Creek drains to the northwest, into the Alabama River. Due to the presence of 

surface water features allowing drainage from Retention Area 1 to off-facility receptors, the 
Site Inspection Report

Army Aviation Support Facility #1, Montgomery, Alabama

AECOM 7-4

surface water and sediment ingestion exposure pathway for off-facility recreational users is 

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

SOURCE PATHWAY RECEPTOR

AOI 1

AFFF Fire 

Suppression 

System and 

AFFF Storage 

in Hazardous 

Waste 

Storage Room

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 Transport and Migration Media Exposure Routes

Inhalation of 

Dust

Ingestion

Ingestion

Ingestion

Ingestion

Human Receptors: 

Current/ Future

Flow-Chart Continues

Partial / Possible Flow

Flow-Chart Stops

Incomplete Pathway

Potentially Complete Pathway

Potentially Complete Pathway 

with Exceedance of SL

/ / / /

LEGEND

Figure 7-1

Conceptual Site Model, AOI 1

AASF #1, Montgomery, 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.

2. Groundwater was not encountered at

AOI 1 during the SI; therefore,

groundwater samples were not collected

and an evaluation based on AOI-specific data cannot be made. However, based

on proximity, the groundwater exposure

pathway at AOI 1 can be reasonably assumed to be similar to that at AOI 2.

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

AFFF Storage 

in Hazmat 

Locker and 

Mobile Fire 

Extinguisher 

Discharge

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 Transport and Migration Media Exposure Routes

Inhalation of 

Dust

Ingestion

Ingestion

Ingestion

Ingestion

Human Receptors: 

Current/ Future

Flow-Chart Continues

Partial / Possible Flow

Flow-Chart Stops

Incomplete Pathway

Potentially Complete Pathway

Potentially Complete Pathway 

with Exceedance of SL

LEGEND

/ / /

Figure 7-2

Conceptual Site Model, AOI 2

AASF #1, Montgomery, 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.

2. Active construction was observed at

the Flight Ramp during the SI.

3. Very shallow, perched groundwater

was encountered at AOI 2 during the SI.

/

/ / / /

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 #1, Montgomery, 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 18 to 21 January 2022 and consisted of utility clearance, 

direct push boring, hollow stem augering, soil sample collection, temporary monitoring well 

installation, and grab groundwater sample collection. Field activities were conducted in accordance 

with the SI QAPP Addendum (AECOM, 2021), except as previously noted in Section 5.9. 

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 13 locations; 

• Three grab groundwater samples from six temporary wells; 

• Two surface water samples from two surface water bodies; and

• Twenty (20) 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 Fire 

Suppression System, Mechanical Room, and Hazardous Waste Storage Room and AOI 2: Flight 

Ramp and Wash Rack. Based on the CSMs developed and revised in light of the SI findings, 

there is potential for exposure to 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:

• In soil, PFOA, PFOS, and PFHxS exceeded their SLs. PFBS and PFNA did not 

exceed the SLs.

 PFOA exceeded the SL of 19 μg/kg in surface soil at AOI01-01 (148 μg/kg) 

and AOI01-04 (165 μg/kg).

 PFOS exceeded the SL of 13 μg/kg in surface soil at AOI01-01 (10,900 J

μg/kg), AOI01-03 (486 μg/kg), AOI01-04 (8,330 μg/kg), and MGM-01 (358 

μg/kg). PFOS also exceeded the SL of 160 μg/kg in subsurface soil at 

AOI01-01 from 5 to 7 feet bgs (499 μg/kg).
Site Inspection Report

Army Aviation Support Facility #1, Montgomery, Alabama

AECOM 8-2

 PFHxS exceeded the SL of 130 μg/kg in surface soil at AOI01-01 (1,890

μg/kg) and AOI01-04 (3,840 μg/kg).

• Groundwater was not encountered at AOI 1.

• PFOA, PFOS, PFBS, and PFHxS were also detected in the surface water. There are 

no established SLs for surface water; therefore, these results are presented for 

informational purposes only.

• Based on the results of the SI, further evaluation of AOI 1 is warranted in an RI.

• At AOI 2:

• In soil, PFOS exceeded the SL of 13 μg/kg in surface soil at AOI02-01 (16.8 J μg/kg).

PFOA, PFBS, PFHxS and PFNA did not exceed their SLs.

• In groundwater, PFOA, PFOS, PFHxS, and PFNA were detected at concentrations 

that exceeded their SLs. PFBS did not exceed its SL.

 PFOA exceeded the SL of 6 ng/L at AOI02-01 (55.9 ng/L) and AOI02-03 

(19.4 ng/L). 

 PFOS exceeded the SL of 4 ng/L at AOI02-01 (499 ng/L), AOI02-03 (8.97 

ng/L), and AOI02-04 (129 ng/L). 

 PFHxS exceeded the SL of 39 ng/L at AOI02-01 (974 ng/L) and AOI02-03

(177 J- ng/L). 

 PFNA exceeded the SL of 6 ng/L at AOI02-01 (13.3 ng/L). 

• PFOS and PFHxS were also detected in the surface water. 

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

Very shallow perched groundwater was encountered at three of the six monitoring wells (AOI02-

01, AOI02-03, and AOI02-04) installed during the SI. Groundwater was not encountered at the 

three remaining planned monitoring wells, including AOI02-05, which was advanced to a depth of 

59 feet bgs. Due to the groundwater observations under localized perched conditions, the flow 

direction of groundwater beneath the facility could not be properly evaluated. At this time, regional 

groundwater at the facility is assumed to flow toward the northwest, as inferred from the flow 

patterns of larger surface water features.

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. 
Site Inspection Report

Army Aviation Support Facility #1, Montgomery, Alabama

AECOM 8-3

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 Fire Suppression 

System, Mechanical Room, 

and Hazardous Waste 

Storage Room

N/A1 N/A Proceed 

to RI 

2 Flight Ramp and 

Wash Rack

N/A Proceed 

to RI

Legend:

1. Groundwater was not encountered within AOI 1 at the time of the SI

N/A = not applicable

= detected; exceedance of the screening levels

= detected; no exceedance of the screening levels

= not detected
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Army Aviation Support Facility #1, Montgomery, Alabama

AECOM 8-4

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Army Aviation Support Facility #1, Montgomery, Alabama

AECOM 9-1

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W912DR17F0192. 9 March.

AECOM. 2018b. Final Programmatic Accident Prevention Plan, Perfluorooctane Sulfonic Acid 

(PFOS) and Perfluorooctanoic Acid (PFOA) Impacted Sites ARNG Installations, Nationwide 

Contract No. W912DR-12-D-0014/W912DR17F0192. July.

AECOM. 2019. Final Site Inspection Report, Air National Guard Phase II, Regional Site 

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AECOM. 2020. Final Preliminary Assessment Report, AASF #1 RW Shepherd, Montgomery, 

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(PFOA) Impacted Sites ARNG Installations, Nationwide. January.

Assistant Secretary of Defense. 2022. Investigation Per- and Polyfluoroalkyl Substances within 

the Department of Defense Cleanup Program. United States Department of Defense. 

6 July. 

BB&E, Inc. 2016. Perfluorinated Compounds Preliminary Assessment, 187th Fighter Wing, 

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DA. 2018. Army Guidance for Addressing Releases of Per- and Polyfluoroalkyl Substances. 

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Systems Manual (QSM) for Environmental Laboratories, Version 5.3. 

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EA Engineering Science and Technology, 2021. SOP No. 042A for Treating Liquid InvestigationDerived Material (Purge water, drilling water, and decontamination fluids).

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Geological Survey of Alabama. 2002. Water in Alabama (Including Basic Water Data). 

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AECOM 9-2

Guelfo, J.L. and Higgins, C.P. 2013. Subsurface Transport Potential of Perfluoroalkyl Acids at 

Aqueous Film-Forming Foam (AFFF)-Impacted Sites. Environmental Science and Technology 

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Higgins, C.P., and Luthy, R.G. 2006. Sorption of perfluorinated surfactants on 

sediments. Environmental Science and Technology 40 (23): 7251-7256.

ITRC. 2018. Environmental Fate and Transport for Per- and Polyfluoroalkyl Substances. March. 

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October 2019 at https://revco.mc-ala.org/. 

MWWSSB. 2021. Biosolids Program. Accessed 4 January 2021 at 

https://www.mwwssb.com/en/Community/Biosolids%20Program

USACE. 2016. Technical Project Planning Process, EM-200-1-2. 26 February.

USEPA. 1980. Comprehensive Environmental Response, Compensation, and Liability Act 

(CERCLA). 

USEPA. 1994. National Oil and Hazardous Substances Pollution Contingency Plan (Final Rule). 

40 CFR Part 300; 59 Federal Register 47384. September.

USEPA. 2001. Risk Assessment Guidance for Superfund, Volume I: Human Health Evaluation 

Manual (Part D, Standardized Planning, Reporting, and Review of Superfund Risk 

Assessments). December.

USEPA. 2017. National Functional Guidelines for Organic Superfund Data Review. OLEM 

9355.0-136, EPA-540-R-2017-002. Office of Superfund Remediation and Technology 

Innovation. January.

USFWS. 2022. Species by County Report, County: Montgomery, Alabama. Environmental 

Conservation Online System. Accessed 12 August 2022 at 

https://ecos.fws.gov/ecp/report/species-listings-by-current-range-county?fips=28097. 

Water Works and Sanitary Sewer Board of the city of Montgomery. 2018. 2018 Water Quality 

Report. Montgomery: City of Montgomery.

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