FINAL

Site Inspection Report 

Army Aviation Support Facility

Windsor Locks, Connecticut

Perfluorooctanesulfonic Acid (PFOS) and 

Perfluorooctanoic Acid (PFOA) Impacted Sites

ARNG Installations, Nationwide

January 2022

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

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

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

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

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

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

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

3.1.1 Wash Rack ...................................................................................................3-1

3.1.2 Building 152..................................................................................................3-1

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

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

4.2 Goals of the Study ..................................................................................................4-2

4.3 Information Inputs ...................................................................................................4-2

4.4 Study Boundaries ...................................................................................................4-2

4.5 Analytical Approach ................................................................................................4-2

4.6 Data Usability Assessment .....................................................................................4-3

4.6.1 Precision.......................................................................................................4-3

4.6.2 Accuracy.......................................................................................................4-4

4.6.3 Representativeness......................................................................................4-5

4.6.4 Comparability................................................................................................4-6

4.6.5 Completeness...............................................................................................4-6

4.6.6 Sensitivity .....................................................................................................4-6

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 PFAS Sampling Equipment Acceptability .......................5-2

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

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

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

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

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

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

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

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

6.1 Screening Levels ....................................................................................................6-1
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6.2 Soil Physicochemical Analyses...............................................................................6-2

6.3 AOI 1.......................................................................................................................6-2

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

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

6.3.3 AOI 1 Conclusions........................................................................................6-4

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

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

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

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

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

7.3 Surface Water and Sediment Exposure Pathway...................................................7-2

7.3.1 AOI 1 ............................................................................................................7-2

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

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

8.2 SI Goals Evaluation ................................................................................................8-1

8.3 Outcome .................................................................................................................8-3

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

Appendix A Data Validation Reports

Appendix B Field Documentation

B1. Log of Daily Notice of Field Activities

B2. Sampling Forms

 B3. Nonconformance and Corrective Action Reports

B4. Survey Data

 B5. Investigation-Derived Waste Polygons

Appendix C Photographic Log

Appendix D TPP Meeting Minutes

Appendix E Boring Logs 

Appendix F Analytical Results

Appendix G Laboratory Reports

Figures

Figure 2-1 Facility Location

Figure 2-2 Facility Topography

Figure 2-3 Groundwater Features

Figure 2-4 Surface Water Features

Figure 2-5 Groundwater Elevations, April 2021

Figure 3-1 Areas of Interest

Figure 5-1 Site Inspection Sample Locations

Figure 6-1 PFOS Detections in Soil

Figure 6-2 PFOA Detections in Soil

Figure 6-3 PFBS Detections in Soil

Figure 6-4 PFOA, PFOS, and PFBS Detections in Groundwater

Figure 7-1 Conceptual Site Model, AOI 1

Tables

Table ES-1 Screening Levels (Soil and Groundwater)

Table ES-2 Summary of Site Inspection Findings

Table ES-3 Site Inspection Recommendations

Table 5-1 Site Inspection Samples by Medium

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

Elevations

Table 6-1 Screening Levels (Soil and Groundwater)

Table 6-2 PFAS Detections in Surface Soil

Table 6-3 PFAS Detections in Shallow Subsurface Soil

Table 6-4 PFAS Detections in Groundwater

Table 8-1 Summary of Site Inspection Findings

Table 8-2 Site Inspection Recommendations
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Acronyms and Abbreviations

6:2 FTS 6:2 Fluorotelomer sulfonic acid

8:2 FTS 8:2 Fluorotelomer sulfonic acid

μg/kg micrograms per kilogram

°C degrees Celsius

°F degrees Fahrenheit

% percent

AASF Army Aviation Support Facility

AECOM AECOM Technical Services, Inc.

AFFF aqueous film forming foam

AOI Area of Interest

ARNG Army National Guard

AST above-ground storage tank

bgs below ground surface 

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act 

CoC chain of custody

CSM conceptual site model

CTANG Connecticut Air National Guard

CTARNG Connecticut Army National Guard

CTDEEP Connecticut Department of Energy and Environmental Protection

DA Department of the Army

DO dissolved oxygen

DoD Department of Defense

DPT direct push technology

DQI data quality indicator

DQO data quality objective

DUA data usability assessment

EDRTM Environmental Data Resources, Inc.TM

EIS extraction internal standards

ELAP Environmental Laboratory Accreditation Program

FedEx Federal Express

ERB equipment rinsate blank

FRB field reagent blank

FTA Fire Training Area

HA Health Advisory 

HDPE high-density polyethylene 

IDW investigation-derived waste

IIS Injection internal standards

ITRC Interstate Technology Regulatory Council

LC/MS/MS liquid chromatography with tandem mass spectrometry

LCS laboratory control spike

LCSD laboratory control spike duplicate

LOD limit of detection

LOQ limit of quantitation
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MDL method detection limit

MS matrix spike

MSD matrix spike duplicate

NELAP National Environmental Laboratory Accreditation Program

NEtFOSAA N-ethyl perfluorooctanesulfonamidoacetic acid

ng/L nanograms per liter

NOAA National Oceanic and Atmospheric Administration

NMeFOSAA N-methyl perfluorooctanesulfonamidoacetic acid

ORP oxidation-reduction potential

OSD Office of the Secretary of Defense

OWS oil-water separator

PA Preliminary Assessment

PFAS per- and polyfluoroalkyl substances

PFBA perfluorobutyrate

PFBS perfluorobutanesulfonic acid

PFCs perfluorinated compounds

PFDA perfluorodecanoic acid

PFDoA perfluorododecanoic acid

PFHpA perfluoroheptanoic acid

PFHxA perfluorohexanoic acid

PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

PFPeA perfluoropentanoic acid

PFTeDA perfluorotetradecanoic acid

PFTrDA perfluorotridecanoic acid

PFUdA perfluoroundecanoic acid

PID photoionization detector

PQAPP Programmatic UFP-QAPP

PVC polyvinyl chloride

QA quality assurance

QAPP Quality Assurance Project Plan

QC quality control

QSM Quality Systems Manual

RI Remedial Investigation

RPD relative percent differences

SI Site Inspection

SL screening level

SOP standard operating procedure

TCRA Time Critical Removal Action

TOC total organic carbon

TPP Technical Project Planning

UCMR 3 Third Unregulated Contaminant Monitoring Rule

UFP Uniform Federal Policy
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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

USGS United States Geological Survey

WLRC Windsor Locks Readiness Center
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Executive Summary

The Army National Guard (ARNG) G9 is performing Preliminary Assessments (PAs) and Site 

Inspections (SIs) at per- and polyfluoroalkyl substances (PFAS)-impacted sites at ARNG facilities 

nationwide. The objective of the SI at each facility is to identify whether there has been a release 

to the environment from the Areas of Interest (AOIs) identified in the PA and determine the 

presence or absence of perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), and 

perfluorobutanesulfonic acid (PFBS) at or above screening levels (SLs). An SI was completed at 

Windsor Locks Army Aviation Support Facility (AASF; also referred to as the “facility”) in Windsor 

Locks, Connecticut. 

The Windsor Locks AASF occupies 37.9 acres along Route 75, adjacent to Bradley International 

Airport, in Windsor Locks, Connecticut. The facility primarily operates as a helicopter operations 

center and fuel station where minor helicopter repairs and servicing are performed (Legette, 

Brashears & Graham, Inc., 2015). The facility includes two maintenance hangars with attached 

office space, the Windsor Locks Readiness Center (WLRC) building, two storage buildings, a 

maintenance shop, and a fenced-in motor pool that includes bermed parking areas for trucks used 

to refuel helicopters. 

During the PA for PFAS, two potential PFAS release areas were identified: the Wash Rack and 

Building 152 (south hangar) (AECOM, 2020). PFAS-containing aqueous film-forming foam 

(AFFF) may have been released during fire training activities at the Wash Rack or from the 

discharge of mobile fire extinguishers to floor drains in Building 152. The potential PFAS release 

areas were grouped into one AOI, AOI 1, which was investigated during the SI. Building 152 and 

the adjacent Building 200 (north hangar) are both equipped with fire suppression systems that 

utilize AFFF. One additional area, the Hazardous Waste Storage Area, was observed during the 

PA because two 5-gallon buckets of AFFF were stored there. No known PFAS releases have 

occurred at Building 200 or the Hazardous Waste Storage Area; therefore, they were not identified 

as part of the AOI during the PA or the SI. However, the SI sampling program covered the majority 

of the facility’s footprint and borings were located downgradient of these storage and use areas 

as a conservative measure. The SI field activities were conducted from 26 to 29 April 2021 and 

included the collection of soil and groundwater samples.

To fulfill the project Data Quality Objectives (DQOs) set forth in the approved SI Quality Assurance 

Project Plan (QAPP) Addendum (AECOM, 2021a), samples were collected and analyzed for a 

subset of 18 PFAS by liquid chromatography with tandem mass spectrometry compliant with 

Quality Systems Manual 5.3 Table B-15. The 18 PFAS analyzed as part of the ARNG SI program 

are specified in Section 5.9 of this Report.

The Department of Defense (DoD) has adopted a policy to retain facilities in the Comprehensive 

Environmental Response, Compensation, and Liability Act (CERCLA) process based on riskbased SLs for soil and groundwater, as described in a memorandum from the Office of the 

Secretary of Defense (OSD) dated 15 September 2021 (Assistant Secretary of Defense, 2021). 

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, and there is a potential release that is likely attributable to ARNG activities, the 

AOI will proceed to a Remedial Investigation (RI), the next phase under CERCLA. The SLs 

established in the OSD memorandum apply to three compounds: PFOA, PFOS, and PFBS, for 

both soil and groundwater. The SLs were calculated using the United States Environmental 

Protection Agency (USEPA) Office of Superfund Sites On-Line Calculator, which was updated on 

8 April 2021 based on the release of the final Human Health Toxicity Values for PFBS (USEPA, 

2021).

Additionally, the USEPA issued drinking water lifetime Health Advisories (HAs) for PFOA and 

PFOS in May 2016 (USEPA 2016a; USEPA, 2016b). The USEPA HAs may also be used as SLs 
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for groundwater samples collected at the facility boundary where off-facility drinking water wells 

are present downgradient; the SLs are presented on Table ES-1 below. All other results presented 

in this report are considered informational in nature and serve as an indication as to whether soil

and groundwater contain or do not contain the 18 PFAS analyzed within the boundaries of the 

facility.

Sample chemical analytical concentrations were compared against the project SLs, as described 

in Table ES-1. A summary of the results of the SI data relative to the SLs is as follows:

• PFOA and PFOS in groundwater at AOI 1 exceeded the individual SLs of 40 nanograms 

per liter (ng/L) at both potential PFAS release areas, Wash Rack (AOI01-02) and Building 

152 (AOI01-04), and in groundwater at upgradient and downgradient locations at the 

facility. The maximum concentrations of PFOA and PFOS were 298 ng/L (at location 

AOI01-03) and 581 ng/L (at location AOI01-08), respectively. Based on the results of the 

SI, further evaluation of AOI 1 is warranted in the RI.

• PFOA, PFOS, and PFBS were detected in soil at AOI 1, indicating a release of PFAScontaining materials occurred; however, the detected concentrations were several orders 

of magnitude lower than the soil SLs.

Table ES-2 summarizes the SI results for soil and groundwater. Based on the conceptual site 

models (CSMs) developed and revised in light of the SI findings, there is potential for exposure 

to drinking water receptors at the facility; however, it is unclear if DoD activities at the facility have 

contributed to PFOA, PFOS, and PFBS concentrations in groundwater.

Table ES-3 summarizes the rationale used to determine if an AOI should be considered for further 

investigation under CERCLA and undergo an RI. Based on the results of this SI, further evaluation 

is warranted in the RI for AOI 1.

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

Analyte

Residential

(Soil)

(μg/kg)a,b

0-2 feet bgs

Industrial/ Commercial 

Composite Worker

(Soil)

(μg/kg)a,b

2-15 feet bgs

Tap Water

(Groundwater)

(ng/L)a,b

USEPA HA

(Groundwater 

representative of 

Drinking Water)

(ng/L)c,d

PFOA 130 1,600 40 70

PFOS 130 1,600 40 70

PFBS 1,900 25,000 600 -

Notes:

a.) Assistant Secretary of Defense, 2019. Risk Based Screening Levels Calculated for PFOS, PFOA, PFBS in Groundwater and Soil using 

United States Environmental Protection Agency’s (USEPA’s) Regional Screening Level Calculator. Hazard Quotient (HQ) = 0.1. 15 October 

2019.

b.) USEPA, 2021. Risk Based Screening Levels Calculated for PFBS in Groundwater and Soil using USEPA’s Regional Screening Level 

Calculator. HQ = 0.1. 8 April 2021.

c.) USEPA. 2016a. Drinking Water Health Advisory (HA) for Perfluorooctanoic Acid (PFOA). Office of Water (4304T). Health and Ecological 

Criteria Division, Washington, DC 20460. USEPA Document Number: 822-R-16-005. May 2016. / USEPA. 2016b. Drinking Water HA for 

Perfluorooctane Sulfonic Acid (PFOS). Office of Water (4304T). Health and Ecological Criteria Division, Washington, DC 20460. USEPA 

Document Number: 822-R-16-004. May 2016.

d.) USEPA HAs apply to the PFOA and PFOS concentrations individually or combined.
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Table ES-2: Summary of Site Inspection Findings

AOI Potential PFAS 

Release Area

Soil –

Source Area

Groundwater –

Source Area

Groundwater –

Facility 

Boundary

1 Wash Rack

1 Building 152

Legend:

N/A = Not applicable 

= detected; exceedance of the screening levels

= detected; no exceedance of the screening levels

= not detected

Table ES-3: Site Inspection Recommendations

AOI Description Rationale Future Action

1 Wash Rack, Building 

152

Exceedances of SLs in groundwater at 

source areas. No exceedances of SLs in 

soil. 

Proceed to RI 
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1. Introduction

1.1 Project Authorization

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

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

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

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

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

Order W912DR17F0192, issued 11 August 2017. The ARNG performed this SI at the Windsor 

Locks Army Aviation Support Facility (AASF) in Windsor Locks, Connecticut. The Windsor Locks 

AASF is also referred to as the “facility” throughout this document.

The SI project elements were performed in compliance with Comprehensive Environmental 

Response, Compensation, and Liability Act (CERCLA; 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 including specific 

requirements for sampling for PFOA, PFOS, and perfluorobutanesulfonic acid (PFBS), and the 

group of related compounds known in the industry as per- and polyfluoroalkyl substances (PFAS). 

The term PFAS is used throughout this report to encompass all PFAS chemicals being evaluated, 

including PFOA, PFOS, and PFBS, which are the key components of the suspected releases 

being evaluated, and the other 15 related compounds listed in the task order.

1.2 SI Purpose

A PA was performed at Windsor Locks AASF (AECOM, 2020) that identified two potential PFAS 

release areas at the facility, which were grouped into one Area of Interest (AOI). The objective of 

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

determine the presence or absence of PFOA, PFOS, and PFBS at or above screening levels 

(SLs).

As stated in the Federal Facilities Remedial Site Inspection Summary Guide (USEPA, 2005), an 

SI has five goals: 

1. Develop information to potentially eliminate a release from further consideration because 

it is determined that it poses no significant threat to human health or the environment;

2. Determine the potential need for a removal action;

3. Collect or develop data to evaluate potential release;

4. Collect data to better characterize the release for more effective and rapid initiation of a 

Remedial Investigation (RI), if determined necessary; and

5. Collect data to determine whether the release is more than likely the result of activities 

associated with the Department of Defense (DoD).

In addition to the USEPA-identified goals of an SI, the ARNG SI also identifies whether there are 

potential off-facility PFAS sources. 
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2. Facility Background

2.1 Facility Location and Description

The Windsor Locks AASF occupies 37.9 acres that consist primarily of two maintenance hangars 

with attached office space, the Windsor Locks Readiness Center (WLRC) building, two storage 

buildings, a maintenance shop, and a fenced-in motor pool that includes bermed parking areas 

for trucks used to refuel helicopters. The facility also contains a hazardous waste storage area, 

above-ground storage tanks (ASTs), a pump house, water tower, emergency diesel generators, 

and a civilian parking lot. The facility is located on Route 75, adjacent to Bradley International 

Airport, in Windsor Locks, Connecticut (Figure 2-1). The facility primarily operates as a helicopter 

operations center and fuel station where minor helicopter repairs and servicing are performed 

(Legette, Brashears & Graham, Inc., 2015). 

Bradley International Airport was acquired by the Federal government in the 1940s as a military 

reservation and deeded to the State of Connecticut in 1948 as surplus property. Between 1949 

and 1955, various legal agreements were executed to provide for use of the field by reserve 

components of the Armed Forces, primarily the US Air Force and Connecticut Air National Guard 

(CTANG). In September 1986, the parcel was transferred from the CTANG to the Connecticut 

ARNG (CTARNG). The transfer of the property from CTANG to CTARNG included numerous 

buildings as well as the wash rack, airport apron, taxiway, and boundary fence. The title to land 

and buildings operated by the CTARNG was listed in the name of the State of Connecticut, 

Department of Aeronautics, and was leased to the US Government until 2002 (Engineering 

Technologies Associates, Inc., 1994). The Secretary of the Army granted the State of Connecticut 

a license to use and occupy for training and support of the CTARNG, effective 1 September 2010 

(under License # DACA33-3-11-032). The lease remains on a year to year basis up to 31 October 

2055.

2.2 Facility Environmental Setting

Windsor Locks AASF is located within the Connecticut Valley Lowlands physiographic region of 

the state (Engineering Technologies Associates, Inc., 1994). The topography of the facility is 

generally level, sloping slightly to the northwest (Figure 2-2). A drainage swale originates along 

the northwestern edge of the facility and continues northwest, off-facility, to an intermittent stream 

called Spencer Brook.

2.2.1 Geology

Windsor Locks AASF lies within the Connecticut Valley Lowlands and is underlain by gently 

sloping sand, silt, and gravel. Fine sand and silt are located beneath the ground surface. Surficial 

material at the facility is mapped as stratified drift and deltaic deposits overlying till with clay 

(Colton, 1960). Historical excavation reports noted a clay layer at depths ranging from 3 to 10 feet 

below ground surface (bgs). Bedrock beneath the facility is mapped as the Portland Arkose 

(Figure 2-3), which is described as a reddish-brown siltstone and sandstone (Schnabel and Eric, 

1964). Depth to bedrock is estimated to be 100 to 150 feet bgs (Handman, 1973). Approximately 

70 percent (%) of the soil underlying the facility is classified as made land, i.e., fill material. The 

underlying soil consists of Ninegrat Fine Sandy Loam, Poquonock Loamy Sand, Windsor Loamy 

Fine Sand, Agawan Fine Sand, Scantic Silt Loam, and Whatley Loam. These soils range from 

sand to silty clay loams with moderate to rapid permeability (SCS, 1962).

Soil borings completed during the SI found poorly graded and well-graded sand as the dominant 

lithology of the unconsolidated sediments below the Windsor Locks AASF; the borings were 

completed at depths between 10 and 15 feet bgs. Isolated layers of clay to silty sand were also 
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observed in the boring logs, at thicknesses ranging from a few inches to 3.5 feet. Many of the logs 

also reported varying percentages of gravel included in the sand packages. These observations 

are consistent with the understood fill material and glaciofluvial depositional environment. 

2.2.2 Hydrogeology

The groundwater beneath the site is classified by the Connecticut Department of Energy and 

Environmental Protection (CTDEEP) as “GA”. Groundwater classified as GA is defined as 

groundwater with the area existing of private water-supply wells or an area with the potential to 

provide water to public or private water supply wells. The CTDEEP presumes that groundwater 

in such an area is, at a minimum, suitable for drinking or other domestic uses without treatment. 

The designated uses for Class GA groundwater are as existing private and potential public or 

private supplies of water suitable for drinking without treatment and as base flow for hydraulically

connected surface water bodies (CTDEEP, 2002). Groundwater features at the facility are shown 

on Figure 2-3. There are currently no potable water wells on the facility. 

A 2018 Environmental Data Resources, Inc.TM (EDRTM) Report indicated that no drinking water 

supply wells are present within a 1-mile radius of the facility (AECOM, 2019). Using additional 

online resources, wells were researched to a 4-mile radius of the facility. The state of Connecticut 

does not have an online well database. According to the US Geological Survey (USGS) National 

Water Information System Mapper, no active wells exist within a 4-mile radius of the facility;

however, 93 inactive USGS monitoring wells were identified within a 4-mile radius of the facility 

(USGS, 2019). Although no other active wells were listed within 4 miles of the facility, agricultural 

areas exist to the north/northwest, and it is possible that unlisted groundwater wells may exist in 

this area. 

Windsor Locks AASF receives its potable water from the Connecticut Water Company. The 

Connecticut Water Company serves East Granby and Windsor Locks in addition to numerous 

other Connecticut towns and cities (Amec Foster Wheeler Environment & Infrastructure, Inc., 

2018). According to the 2017 Water Quality Report for the Connecticut Water Northern Western 

Water System (serving Windsor Locks), the water supply source for Windsor Locks is the 

Metropolitan District (MDC), a non-profit municipal corporation that provides potable water and 

sewerage services (MDC, 2019). The MDC water supply source consists of a system of reservoirs 

that includes the Barkhamsted Reservoir and the Nepaug Reservoir (MDC, 2019). The two 

reservoirs are approximately 14 miles and 16 miles west of the Windsor Locks AASF, respectively. 

Available Third Unregulated Contaminant Monitoring Rule (UCMR 3) data for Connecticut does 

not indicate that PFAS have been detected in either of the aforementioned MDC surface water 

reservoirs (USEPA, 2017a). 

Depths to water measured in April 2021 during the SI ranged from 3.37 to 8.11 feet bgs. 

Groundwater elevation contours from the SI are presented on Figure 2-5 and indicate 

groundwater flow direction is towards the drainage swale on both the western and eastern 

portions of the facility. West of the drainage swale, groundwater flow is generally to the northeast

across the facility towards the drainage swale, while east of the drainage swale, groundwater flow 

is to the west-southwest back toward the drainage swale. Hydraulic conductivity values measured 

during a 2008 Phase III Investigation ranged from 0.5 to 33 feet per day (Fuss & O’Neil, 2008).

2.2.3 Hydrology

The nearest surface water body to the facility is Spencer Brook, which is located approximately 

300 feet northwest of the facility at its closest point (Figure 2-4). Spencer Brook is not classified 

by the State of Connecticut, and it is therefore assumed to be a Class A surface water body. Class 

A surface water bodies support the following designated uses: potential drinking water supply, fish 

and wildlife habitat, recreational use, agricultural, industrial supply and other legitimate uses, 

including navigation (CTDEEP, 2002). 
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Windsor Locks AASF is drained by Spencer Brook, an intermittent stream that discharges to 

Stoney Brook, a perennial stream 6,300 feet downstream of the facility. Stoney Brook discharges 

into the Connecticut River 5.3 miles further downstream. The average flow of the Connecticut 

River measured at State Route 190 is 16,640 cubic feet per second. The average flow rate of 

Stoney Brook is 20.4 cubic feet per second, based on the period 1981 to 1992 at the South Grand 

Street stream gage.

The western portion of the facility is drained by a stormwater detention system and a surface 

swale to the west of the parking apron. This system drains the tank farm area and the parking 

apron, as well as areas off-facility. The eastern portion of the facility is drained by a separate 

stormwater detention system and a drainage swale to the east of Building 200. The stormwater 

detention system east of Building 152 originates on State of Connecticut property. The western 

and eastern drainage features converge in the northern portion of the facility, from where the 

drainage is routed into a concrete swale to the north of the facility and subsequently to Spencer 

Brook.

The Windsor Locks AASF facilities discharge stormwater runoff associated with industrial 

activities into surface waters under state permits. The facility is also permitted to discharge water 

associated with the wash rack’s grit separator and the AASF oil-water separator (OWS) and floor 

drain system into sanitary sewers.

2.2.4 Climate

Data from Hartford Bradley International Airport, Connecticut indicate that the annual average 

temperature between 1981 and 2010 was 50.6 degrees Fahrenheit (°F) (National Oceanic and 

Atmospheric Administration [NOAA], 2018). The warmest months are July and August, with 

normal daily average temperatures of 73.6 °F and 71.9 °F, respectively. January is the coldest 

month, with an average temperature of 26.1 °F. Average annual precipitation measured from 1981 

to 2010 at the airport was 45.85 inches. Rainfall is heaviest during the months of May through 

July, averaging approximately 4.3 inches per month; January and February are the driest months. 

Average monthly precipitation ranges from 2.89 inches in February to 4.37 inches in October 

(NOAA, 2018). 

2.2.5 Current and Future Land Use

Windsor Locks AASF is an operations center used by the CTARNG for the routine maintenance 

and minor repair on military helicopters and fixed-wing aircraft. A bulk fuel facility has been 

operating at the Windsor Locks AASF since the early 1970s. The facility includes two maintenance 

hangars with attached office space, the WLRC building, two storage buildings, a maintenance 

shop, a fenced-in motor pool that includes bermed parking areas fuel trucks, a hazardous waste 

storage area, ASTs, a pump house, water tower, emergency diesel generators, and a civilian 

parking lot. Future use of the Windsor Locks AASF is anticipated to remain the same.

2.2.6 Sensitive Habitat and Threatened/ Endangered Species 

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

proposed, and/ or are listed as candidate species in Hartford County, Connecticut (US Fish and 

Wildlife Service [USFWS], 2021). 

• Insects: Monarch butterfly, Danaus plexippus (candidate); Cobblestone tiger beetle, 

Cicindela marginipennis (resolved taxon)

• Mammals: Northern long-eared bat, Myotis septentrionalis (threatened)

• Clams: Dwarf wedgemussel, Alasmidonta heterodon (endangered)
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• Flowering plants: Small whorled pogonia, Isotria medeoloides (threatened)

2.3 History of PFAS Use 

Two potential PFAS release areas were identified during the PA at the Windsor Locks AASF, 

where aqueous film forming foam (AFFF) may have been used or released historically (AECOM, 

2020). Windsor Locks AASF includes two maintenance hangars: Building 200 (north hangar) and 

Building 152 (south hangar). Both hangars are equipped with fire suppression systems that utilize 

AFFF. Although there are no documented releases from the fire suppression systems, AFFF may 

have been released at the facility during fire training activities. Notably, between 2003 and 2015, 

AFFF was used to extinguish controlled burns at the Wash Rack during fire training, and mobile 

fire extinguishers containing AFFF were discharged to the floor drains in Building 152. These two

potential PFAS release areas were grouped into one AOI based on proximity to one another and 

presumed groundwater flow. One additional area, the Hazardous Waste Storage Area, was 

observed during the PA because two 5-gallon buckets of AFFF were stored there. No known PFAS 

releases have occurred at Building 200 or the Hazardous Waste Storage Area; therefore, they 

were not identified as part of the AOI during the PA or the SI. However, the SI sampling program 

covered the majority of the facility’s footprint and borings were located downgradient of these 

storage and use areas as a conservative measure. A description of AOI 1 is presented in Section

3.
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3. Summary of Areas of Interest 

Based on the PA findings, two potential PFAS release areas, the Wash Rack and Building 152, 

were identified at Windsor Locks AASF and grouped into one AOI (AECOM, 2020). The potential 

PFAS release areas are shown on Figure 3-1, and a summary of the AOI is presented below.

3.1 AOI 1 

AOI 1 consists of two potential PFAS release areas, as described below.

3.1.1 Wash Rack

The Wash Rack at Windsor Locks AASF is located west of Building 152 (south hangar), near the

southern boundary of the CTARNG Windsor Locks AASF property. The geographic coordinates

of the Wash Rack are approximately 41°56'38.5"N and 72°40'26.7"W. During fire training events 

at the Wash Rack, a pan containing flammable liquid was ignited in the center of the Wash Rack,

and mobile fire extinguishers containing AFFF were discharged to put out the flames. Between 

six and ten mobile extinguishers containing 30 gallons of an AFFF/water dilution would be used 

per training exercise. Formal training records were not kept. The AFFF product used during 

training events is unknown; however, Tri-MaxTM -40 oF AFFF solution and 3M AFFF Type 3 (3%) 

have been stored at the facility in 5-gallon buckets and are believed to have been used during 

exercises. Training exercises at the Wash Rack that resulted in the discharge of AFFF are 

expected to have occurred once per year between 2003 and 2015, according to personnel 

interviews. Additionally, the facility Avionics Small Shops Chief stated that a fire training 

demonstration performed by the Connecticut Fire Academy (or their vendor/supplier) occurred at 

the Wash Rack within the last 5 years. No other information regarding this event was available 

during the PA. The Windsor Locks AASF Fire Marshall confirmed via correspondence after the 

site visit that fire training exercises since August 2015 have been conducted solely at the nearby 

off-facility Connecticut Fire Academy (AECOM, 2020).

The Wash Rack is a slightly depressed concrete platform approximately 80 feet long by 80 feet 

wide with a catch basin at the center of the depression. Discharge from the catch basin currently 

flows to a below-grade stormwater detention system when the Wash Rack is not in use. If the 

Wash Rack is being used to wash aircrafts, then discharge is diverted via a valve to an 

underground 2,500-gallon OWS and then to municipal sanitary sewers. AFFF released during 

known fire training events at the Wash Rack would have been discharged to the sanitary sewer 

system via the Wash Rack; however, the recent installation of a valve to divert stormwater runoff 

through the Wash Rack to the stormwater detention system may result in residual PFAS reaching 

stormwater outfalls. The stormwater detention system discharges to wetlands in the northeastern 

portion of the facility, and water eventually flows to Spencer Brook.

3.1.2 Building 152

Building 152, the south hangar at Windsor Locks AASF, is located on the south side of and

adjacent to Building 200, the north hangar. The approximate geographic coordinates of Building 

152 are 41°56'39.6"N and 72°40'23.6"W. Building 152 is equipped with a fire suppression system 

that uses National Foam Aer-o-lite 3% AFFF. The AFFF that supplies the fire suppression system 

is stored in a 900-gallon tank in the AFFF Tank Storage Room located between the north and 

south hangars. The fire suppression system was installed in 1997 and is serviced quarterly by the 

contractor Fire Protection Team. The fire suppression system is also sampled annually to assure 

the appropriate AFFF product concentration is adequate. Annual suppression system testing uses 

only water, and CTARNG staff indicated that an AFFF release has never occurred as a result of 

suppression system testing. No incidents resulting in an AFFF release have occurred in the AFFF 

Tank Storage Room, and no known releases of PFAS have occurred from the fire suppression 
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system. Handheld dry chemical fire extinguishers are also stored in the room for use in the event 

of an emergency.

Mobile fire extinguishers that contained AFFF were discharged to the floor drains in Building 152 

between 2003 and 2015, though less frequently than fire training events at the Wash Rack. 

Information sources conflicted on whether AFFF discharges occurred to floor drains in Building 

152; however, discharge events have been conservatively presumed to have occurred, based on 

the statements of some personnel. Discharges of AFFF to the Building 152 floor drains were not 

documented. Based on information gathered during the PA, between six and ten mobile 

extinguishers containing 30 gallons of an AFFF/water dilution would be used per training exercise. 

The AFFF product used during training events is unknown; however, Tri-MaxTM -40oF AFFF 

solution and 3M AFFF Type 3 (3%) have been stored at the facility in 5-gallon buckets and are 

believed to have been used during exercises. Floor drains in Building 152 connect underground 

to a 2,500-gallon OWS south of the hangar, which discharges to municipal sanitary sewers 

(AECOM, 2020).
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4. Project Data Quality Objectives

Project Data Quality Objectives (DQOs) are qualitative and quantitative statements that specify 

the quality of data and define the level of certainty required to support project decision-making

process. The specific DQOs established for this facility are described below. These DQOs were 

developed in accordance with the USEPA’s seven-step iterative process (USEPA, 2006).

4.1 Problem Statement

The following problem statement was developed during project planning:

The presence of PFAS, which may pose a risk to human health or the environment, in 

environmental media at the facility is currently unknown. PFAS are classified as emerging 

environmental contaminants that are garnering increasing regulatory interest due to their potential 

risks to human health and the environment. The regulatory framework for managing PFAS at both 

the federal and state level continues to evolve. 

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 Office of the Secretary of 

Defense (OSD) dated 15 October 2019 (Assistant Secretary of Defense, 2019). 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 three compounds: PFOS, PFOA, and PFBS. The SLs were calculated using the USEPA 

Office of Superfund Sites On-Line Calculator, which was updated on 8 April 2021 based on the 

release of the final Human Health Toxicity Values for PFBS (USEPA, 2021).

Additionally, the USEPA issued drinking water lifetime Health Advisories (HAs) for PFOA and 

PFOS in May 2016 (USEPA 2016a; USEPA, 2016b). The USEPA HAs may also be used as SLs 

for groundwater samples collected at the facility boundary where off-facility drinking water wells 

are present downgradient. The SLs are presented in Section 6.1 of this Report.

The following quotes from the DA policy documents form the basis for this project (DA, 2016; DA, 

2018): 

• “The Army will research and identify locations where PFOS- and/or PFOA-containing 

products, such as AFFF, are known or suspected to have been used. Installations shall 

coordinate with installation/facility fire response or training offices to identify AFFF use or 

storage locations. The Army will consider FTAs, AFFF storage locations, hangars/buildings 

with AFFF suppression systems, fire equipment maintenance areas, and areas where 

emergency response operations required AFFF use as possible source areas. In addition, 

metal plating operations, which used certain PFOS-containing mist suppressants, shall be 

considered possible source areas.” 

• “Based on a review of site records...determine whether a CERCLA PA is appropriate for 

identifying PFOS/PFOA release sites. If the PA determines a PFOS/PFOA release may 

have occurred, a CERCLA SI shall be conducted to determine presence/absence of 

contamination.” 

• “Identify sites where perfluorinated compounds are known or suspected to have been 

released, with the priority being those sites within 20 miles of the public systems that tested 

above USEPA HA levels.” (USEPA, 2016a; USEPA, 2016b).
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4.2 Goals of the Study

The following goals were established for this SI:

1. Determine the presence or absence of PFOA, PFOS, and PFBS at or above SLs.

2. Develop information to potentially eliminate a release from further consideration because 

it is determined that it poses no significant threat to human health or the environment.

3. Determine the potential need for a Time Critical Removal Action (TCRA) (applies to 

drinking water only). The primary actions that will be considered include provision of 

alternative water supplies or wellhead treatment.

4. Collect data to better characterize the release areas for more effective and rapid initiation 

of a RI (if determined necessary).

5. If PFOA, PFOS, and PFBS are determined to be present, aim to evaluate whether the 

concentrations can be attributed to on-facility or off-facility sources that were identified 

within 4 miles of the installation as part of the PA (e.g., fire stations, major manufacturers, 

other DoD facilities).

6. Determine whether a potentially complete pathway exists between the source and 

potential receptors and whether ARNG is the likely source of the contamination.

4.3 Information Inputs

Primary information inputs included:

• The PA for Windsor Locks AASF (AECOM, 2020);

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

with the site-specific Uniform Federal Policy (UFP)-Quality Assurance Project Plan (QAPP)

Addendum (AECOM, 2021a); and

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

parameters measured at the time of sampling.

4.4 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).

4.5 Analytical Approach

Samples were analyzed by Pace Analytical Gulf Coast, accredited under the 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 and decision rules as defined in the SI QAPP Addendum (AECOM, 

2021a). These rules governed response actions based on the results of the SI sampling effort.

The decision rules described in the Worksheet #11 of the SI QAPP Addendum identify actions

based on the following:
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Groundwater:

• Is there a human receptor within 4 miles of the facility?

• What is the concentration of PFOA, PFOS, and PFBS at the potential release areas?

• What is the concentration of PFOA, PFOS, and PFBS at the facility boundary upgradient 

and downgradient of the potential release areas?

• What does the conceptual site model (CSM) suggest in terms of source, pathway and 

receptor? 

Soil:

• What is the concentration of PFOA, PFOS, and PFBS in shallow surface soil (0 to 2 feet 

bgs)?

• What is the concentration of PFOA, PFOS, and PFBS in deep soil (i.e., capillary fringe)?

• What does the CSM suggest in terms of source, pathway, and receptor? 

Soil and groundwater samples were collected from each of the potential release areas. 

Groundwater was encountered at approximately 3.37 to 8.11 feet bgs.

4.6 Data Usability Assessment

The Data Usability Assessment (DUA) 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 the facility-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 decision-making (DoD, 2019a; DoD, 2019b; 

USEPA, 2017b).

Data Quality Indicators (DQIs) (Precision, Accuracy, Representativeness, Comparability, 

Completeness, and Sensitivity) are important components in assessing data usability. These 

DQIs were evaluated in the subsequent sections and demonstrate that the data presented in this 

SI report are of high quality. Although the SI data are considered reliable, some degree of 

uncertainty can be associated with the data collected. Specific factors that may contribute to the 

uncertainty of the data evaluation are described below. The Data Validation Report (Appendix A) 

presents explanations for all qualified data in greater detail.

4.6.1 Precision

Precision is the degree of agreement among repeated measurements of the same characteristic 

on the same sample or on separate samples collected as close as possible in time and place. 

Field sampling precision is measured with the field duplicate relative percent differences (RPD); 

laboratory precision is measured with calibration verification, internal standard recoveries, and

laboratory control spike (LCS) and matrix spike (MS) duplicate RPD.

Extraction internal standards (EIS) were added by the laboratory during sample extraction to 

measure relative responses of target analytes and used to correct for bias associated with matrix 

interferences and sample preparation efficiencies, injection volume variances, mass spectrometry 

ionization efficiencies, and other associated preparation and analytical anomalies. Several EIS 

area counts were outside of quality control (QC) limits. The associated field sample results were 

qualified due to low recoveries and were qualified as estimated with a high bias while non-detects 
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were qualified “UJ”. The field sample results are considered usable as qualified as estimated 

values.

Injection internal standards (IIS) were added by the laboratory after sample extraction and prior 

to analysis as a requirement of DoD QSM 5.3 to measure relative responses of target analytes. 

Even though not required, the IIS are still added to the sample after extraction as an additional 

QC measure. The IIS percent recoveries were within the established precision limits presented in 

the SI QAPP Addendum (AECOM, 2021a).

LCS/LCS duplicate (LCSD) pairs were prepared by addition of known concentrations of each 

analyte in a matrix-free media known to be free of target analytes. LCS/LCSD pairs were analyzed 

for every analytical batch to demonstrate the ability of the laboratory to detect similar 

concentrations of a known quantity in matrix-free media. The LCS/LCSD samples were within the 

project established precision limits presented in the QAPP Addendum (AECOM, 2021a).

MS/MS duplicate (MSD) samples were prepared, analyzed, and reported for all preparation 

batches. MS/MSD samples demonstrated that the analytical system was in control for the matrix 

being tested, with one exception. MS/MSD samples were submitted to the laboratory for analysis 

at a rate of 5%. The MS/MSD samples were within the project established precision limits 

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

Field duplicate samples were collected at a rate of 10% to assess the overall sampling and 

measurement precision for this sampling effort. The field duplicate samples were analyzed for 

PFAS and general chemistry parameters. The field duplicate samples were within the project 

established precision limits presented in the SI QAPP Addendum (AECOM, 2021a), with limited 

exceptions. One field duplicate pair displayed a positive result for perfluoroheptanoic acid 

(PFHpA) and a non-detect result for perfluorononanoic acid (PFNA) in the parent sample, while 

the associated field duplicate displayed a non-detect result for PFHpA and a positive result for 

PFNA. The field duplicate pair results were qualified as estimated and are considered usable as 

qualified. 

4.6.2 Accuracy

Accuracy is a measure of confidence in a measurement. The smaller the difference between the 

measurement of a parameter and its "true" or expected value, the more accurate the 

measurement. The more precise or reproducible the result, the more reliable or accurate the 

result. Accuracy is measured through percent recoveries in the LCS/LCSD, MS/MSD, and 

surrogates.

LCS/LCSD samples were prepared by addition of known concentrations of each analyte in a 

matrix-free media known to be free of target analytes. LCS/LCSD samples were analyzed for 

every analytical batch and demonstrated that the analytical system was in control during sample 

preparation and analysis. The LCS/LCSD samples were within the project established accuracy 

limits presented in the QAPP Addendum (AECOM, 2021a).

MS/MSD samples were prepared, analyzed, and reported at a rate of 5%. MS/MSD samples 

demonstrated that the analytical system was in control for the matrix being tested, with several 

exceptions. Parent samples AOI01-10-SB-03-05 and AOI01-08-00-02 displayed MS/MSD 

percent recoveries outside the QC limits for several analytes. The field sample results associated 

with the high recoveries were qualified as estimated with a potential high bias and are considered 

usable as qualified.

Calibration verifications were performed routinely to ensure that instrument responses for all 

calibrated analytes were within established QC criteria. The calibration verifications performed 

during the laboratory analyses were within the project established precision limits presented in 

the QAPP Addendum (AECOM, 2021a).
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AECOM 4-5

4.6.3 Representativeness

Representativeness qualitatively expresses the degree to which data accurately reflect site 

conditions. Factors that affect the representativeness of analytical data include appropriate 

sample population definitions, proper sample collection and preservation techniques, analytical 

holding times, use of standard analytical methods, and determination of matrix or analyte 

interferences. 

Relating to the use of standard analytical methods, the laboratory followed the method as 

established in PFAS by liquid chromatography with tandem mass spectrometry (LC/MS/MS)

compliant with Quality Systems Manual (QSM) 5.3 Table B-15, including the specific preparation 

requirements (i.e., ENVI-Carb or equivalent used), mass calibration, and spectra. Additionally, the 

ion transitions identified in Table B-15 were monitored, standards that contained both branch and 

linear isomers were used, when available, and isotopically labeled standards were used for 

quantitation.

Field QC samples were collected to assess the representativeness of the data collected. Field 

duplicates were collected at a rate of 10% for all field samples, while MS/MSD samples were 

collected at a rate of 5%. All preservation techniques were followed by the field staff, and all 

technical and analytical holding times were met by the laboratory. The laboratory used approved 

standard methods in accordance with the QAPP Addendum (AECOM, 2021a) for all analyses.

Instrument blanks and method blanks were prepared by the laboratory in each batch as a negative 

control. Several laboratory and method blanks displayed concentrations for target analytes 

greater than the detection limits including PFBA, PFBS, PFOS, and perfluorohexanesulfonic acid 

(PFHxS). The associated investigative field samples that displayed positive results at levels 

approximate to the blank detections were qualified as likely false positives and are considered 

usable as qualified.

One field reagent blank (FRB) was collected during the SI. Additionally, multiple equipment rinsate 

blanks (ERBs) were collected for soil samples. Several ERBs displayed detections for PFOS 

greater than the detection limit. The associated investigative field samples were either non-detect 

or were positive and displayed concentrations significantly greater than the blank detections. After 

review of the field documentation, it was determined that an ERB was not collected for the surface 

soil samples collected via hand auger. A conservative approach was taken to treat detections in 

the surface soil samples collected via hand auger as true positives because the field investigation 

had concluded and collecting an ERB retroactively would not have measured the decontamination 

efficiency as experienced a the project site. Additionally, this approach was taken because the 

potential of false positives at low concentrations was relatively low (no soil sample was qualified 

due to any aqueous blank during this investigation). This deviation from the SI QAPP Addendum 

is noted in Section 5.8 of this report and is also documented in a Nonconformance and Corrective 

Action Report (Appendix B3).

A sample of the water used for decontamination of the drill rig was collected in advance of the 

field effort. The drill rig decontamination sample displayed detections for PFBA, perfluorohexanoic 

acid (PFHxA), PFOS, and PFOA. The associated investigative field samples were either nondetect or were positive and displayed concentrations significantly greater than the blank 

detections.

Field samples were extracted and analyzed within the appropriate holding time in order to 

qualitatively express the degree to which data accurately reflect site conditions with no

exceptions. Overall, the data are usable for evaluating the presence or absence of PFAS at the 

facility. Sufficient usable data were obtained to meet the objectives of the SI.
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AECOM 4-6

4.6.4 Comparability

Comparability is the extent to which data from one study can be compared directly to either past 

data from the current project or data from another study. Using standardized sampling and 

analytical methods, units of reporting, and site selection procedures help ensure comparability. 

Standard field sampling and typical laboratory protocols were used during the SI and are 

considered comparable to ongoing investigations.

4.6.5 Completeness

Completeness is a measure of the amount of valid data obtained from a measurement system 

compared to the amount of data expected under normal conditions. The laboratory provided data 

meeting system QC acceptance criteria for all samples tested. Project completeness was 

determined by evaluating the planned versus actual quantities of data. Percent completeness per 

parameter is as follows and reflects the exclusion of “X” flagged data, if applicable:

• PFAS in groundwater by LC/MS/MS compliant with QSM 5.3 Table B-15 at 100%

• PFAS in soil by LC/MS/MS compliant with QSM 5.3 Table B-15 at 100%

• pH in soil by USEPA Method 9045D at 100%

• Total organic carbon (TOC) by USEPA Method 9060 at 100%

At some boring locations, only two soil samples could be collected due to the shallow depth to 

groundwater. This is described further in Section 5.2.

4.6.6 Sensitivity

Sensitivity is the capability of a test method or instrument to discriminate between measurement 

responses representing different levels (e.g., concentrations) of a variable of interest. Examples 

of QC measures for determining sensitivity include laboratory fortified blanks, a method detection 

limit (MDL) study, and calibration standards at the limit of quantitation (LOQ). In order to meet the 

needs of the data users, project data must meet the measurement performance criteria for 

sensitivity and project LOQs specified in the QAPP Addendum (AECOM, 2021a). Although two 

instrument sensitivity checks displayed high percent recoveries for perfluorotridecanoic acid

(PFTrDA) and perfluorooctanesulfonamidoacetic acid (NEtFOSAA), no field sample results were 

associated with the PFTrDA exceedance, and the field sample results associated with the 

NEtFOSAA exceedance were all non-detect; therefore, these anomalies had no impact on the 

data. The laboratory provided the requested MDL studies and provided applicable calibration 

standards at the LOQ. In order to achieve the DQOs for sensitivity outlined in the QAPP 

Addendum (AECOM, 2021a), the laboratory reported all field sample results at the lowest possible 

dilution. Additionally, any analytes detected below the LOQ and above the MDL were reported 

and qualified “J” as estimated values by the laboratory.
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AECOM 5-1

5. Site Inspection Activities

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

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

in accordance with the following approved documents:

• Final Preliminary Assessment Report, Windsor Locks Army Aviation Support Facility, 

Connecticut dated February 2020 (AECOM, 2020);

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

dated March 2018 (AECOM, 2018a);

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

Army Aviation Support Facility, Windsor Locks, Connecticut dated March 2021 (AECOM, 

2021a);

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

• Final Site Safety and Health Plan, Army Aviation Support Facility, Windsor Locks, 

Connecticut dated April 2021 (AECOM, 2021b).

The SI field activities were conducted from 26 to 29 April 2021 and consisted of utility clearance,

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

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

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

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

LC/MS/MS compliant with QSM 5.3 Table B-15 to fulfill the project DQOs:

• 26 soil samples from 10 boring locations;

• 10 grab groundwater samples from 10 temporary well locations; and

• 18 quality assurance (QA) 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, a Nonconformance and 

Corrective Action Report is provided in Appendix B3, land survey data are provided in Appendix 

B4, and investigation-derived waste (IDW) polygons are provided in Appendix B5. Additionally, 

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

5.1 Pre-Investigation Activities

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

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

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

5.1.1 Technical Project Planning

The USACE TPP Process, Engineer Manual (EM) 200-1-2 (USACE, 2016) defines four phases 

to project planning: 1.) defining the project phase; 2.) determining data needs; 3.) developing data 

collection strategies; and 4.) finalizing the data collection plan. The process encourages 

stakeholder involvement in the SI, beginning with defining overall project objectives, including 

quantitative and qualitative DQOs, and formulating a sampling approach to address the AOIs 

identified in the PA. 
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A combined TPP Meeting 1 and 2 was held on 21 December 2020, 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, CTARNG, USACE, CTDEEP, and representatives 

familiar with the facility, the regulations, and the community. Stakeholders were provided the

opportunity to make comments on the technical sampling approach and methods at the combined 

TPP Meeting 1 and 2. The outcome of the combined TPP Meeting 1 and 2 was memorialized in 

the SI QAPP Addendum (AECOM, 2021a), and meeting minutes are included in Appendix D.

A TPP Meeting 3 will be held after the field event to discuss the results of the SI. Future TPP 

meetings will provide an opportunity to discuss the results and findings, and future actions, where 

warranted.

5.1.2 Utility Clearance

AECOM’s drilling subcontractor, Cascade Technical Services, LLC. placed a ticket with the “Call 

Before You Dig” Connecticut utility clearance provider to notify them of intrusive work on 16 April 

2021. However, because the AASF is a private facility, the participating “Call Before You Dig”

locators did not clear utilities at the entire facility. Therefore, AECOM contracted Underground 

Surveying, LLC., a private utility location service, to perform utility clearance. Underground 

Surveying, LLC. performed utility clearance of the proposed boring locations on 26 April 2021 with 

input from the AECOM field team and Windsor Locks AASF facility staff. General locating services 

and ground-penetrating radar were used to complete the clearance. Additionally, the first 5 feet of 

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

where utilities would typically be encountered.

5.1.3 Source Water and PFAS Sampling Equipment Acceptability

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

acceptable for use in a PFAS investigation prior to the start of field activities. A sample from a 

potable water source at Windsor Locks AASF was collected on 26 March 2021, prior to 

mobilization, and analyzed for PFAS by LC/MS/MS compliant with QSM 5.3 Table B-15. The 

results of the decontamination water sample are provided in Appendix F. A discussion of the 

results is presented in Section 4.6.3.

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

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

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

QAPP Addendum (AECOM, 2021a). Prior to the start of field work each day, a PFAS 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 direct push technology (DPT), in accordance with the SI QAPP 

Addendum (AECOM, 2021a). A GeoProbe® 7822DT dual-tube sampling system was used to 

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

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

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

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

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

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

encountered at 6 feet bgs or shallower, only two soil samples were collected per boring, in 
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AECOM 5-3

accordance with the QAPP Addendum (AECOM, 2021a). Specifically, only two soil samples were 

collected at locations AOI01-01, AOI01-02, AOI01-04, and AOI01-06 for this reason.

The soil cores were continuously logged for lithological descriptions by a 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 non-treated 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.

Soil borings completed during the SI found poorly graded and well-graded sand as the dominant 

lithology of the unconsolidated sediments below the Windsor Locks AASF. The borings were 

completed at depths between 10 and 15 feet bgs. Isolated layers of clay to silty sand were also 

observed in the boring logs, at thicknesses ranging from a few inches to 3.5 feet. Many of the logs 

also reported varying percentages of gravel included in the sand packages. These observations 

are consistent with the understood fill material and glaciofluvial depositional environment.

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 for PFAS (LC/MS/MS compliant with QSM 5.3 Table B-15), TOC 

(USEPA Method 9060A), and pH (USEPA Method 9045D), in accordance with the SI QAPP 

Addendum (AECOM, 2021a).

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

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

same parameters as the accompanying samples. In instances when non-dedicated sampling 

equipment was used, such as a hand auger for the shallow soil samples, ERBs were collected at 

a rate of 5% and analyzed for the same parameters as the soil samples. As stated previously, 

after review of the field documentation, it was determined that an ERB was not collected for the 

surface soil samples collected via hand auger. This deviation from the SI QAPP Addendum is 

noted in Section 5.8 of this report and is also documented in a Nonconformance and Corrective 

Action Report (Appendix B3). ERBs were collected from the DPT shoe in accordance with the 

QAPP. 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, 2021a) using bentonite chips 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

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.

The temporary wells were allowed to recharge after installation before collection of groundwater 

samples. After the recharge period, groundwater samples were collected using a peristaltic pump 

with PFAS-free HDPE tubing. Each sample was collected into laboratory-supplied PFAS-free 

HDPE bottles and labeled using a PFAS-free marker or pen. The temporary wells were purged at 

a rate determined in the field to reduce turbidity and draw down prior to sampling. Water quality 
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AECOM 5-4

parameters (e.g., temperature, specific conductance, pH, dissolved oxygen [DO], and oxidationreduction potential [ORP]) were measured using a water quality meter and recorded on the field 

sampling form (Appendix B2) after each grab sample was collected. Additionally, a subsample 

of each groundwater sample was collected in a separate container, and a shaker test was 

completed to identify if there was any foaming. No foaming was noted in any of the groundwater 

samples.

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

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

standard CoC procedures to the laboratory and analyzed for PFAS by LC/MS/MS compliant with 

QSM 5.3 Table B-15 in accordance with the SI QAPP Addendum (AECOM, 2021a).

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

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

same parameters as the accompanying samples. One FRB 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, 2021a) 

by removing the PVC and backfilling the hole with bentonite chips. Temporary wells were installed 

in grass areas to avoid disturbing concrete or asphalt.

5.4 Synoptic Water Level Measurements

Groundwater gauging was performed prior to temporary well sampling. Groundwater elevation 

measurements were collected from the 10 new temporary monitoring wells. Water level 

measurements were taken from the northern side of the well casing. A groundwater flow contour 

map is provided in Figure 2-5. Groundwater elevation data are provided in Table 5-2.

5.5 Surveying

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

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

Survey data from the newly installed wells on the facility were collected on 29 April 2021, in the 

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

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

provided in Appendix B4.

5.6 Investigation-Derived Waste

As of the date of this report, the disposal of PFAS IDW is not regulated federally. PFAS IDW 

generated during the SI is considered non-hazardous waste and was managed in accordance 

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

of PFAS, Q18 (DA, 2018).

Soil IDW (i.e., soil cuttings) generated during the SI activities were left in place at the point of the 

source. The soil cuttings were distributed on the ground surface on the downgradient side of the 

boring, with the exception of the IDW from AOI01-05, which was placed on the downgradient side 

of AOI01-10 at the request of the facility. Additionally, IDW from AOI01-04 was placed 

approximately 80 feet east of the boring at the request of the facility. The soil IDW was not sampled 

and assumes the PFAS characteristics of the associated soil samples collected from that source 

location. 

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

decontamination fluids) were discharged directly to the ground surface slightly downgradient of 
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AECOM 5-5

the source. The liquid IDW was not sampled and assumes the PFAS characteristics of the 

associated groundwater samples collected from that source location.

Geographic coordinates were collected using a global positioning system around each location 

where IDW was placed (i.e., an IDW polygon). The IDW polygons are displayed on the figure in 

Appendix B5. Other solids such as spent personal protective equipment, plastic sheeting, tubing, 

rope, unused monitoring well construction materials, and other environmental media generated 

during the field activities were disposed of at a licensed solid waste landfill.

5.7 Laboratory Analytical Methods

Samples were analyzed for a subset of 18 PFAS by LC/MS/MS compliant with QSM 5.3 Table B15 at Pace Analytical Gulf Coast in Baton Rouge, Louisiana, a DoD ELAP and NELAP certified 

laboratory. The 18 PFAS analyzed as part of the ARNG SI program include the following:

• 6:2 fluorotelomer sulfonic acid (6:2 FTS)

• 8:2 fluorotelomer sulfonic acid (8:2 FTS)

• N-ethyl 

perfluorooctanesulfonamidoacetic acid 

(NEtFOSAA)

• N-methyl 

perfluorooctanesulfonamidoacetic acid 

(NMeFOSAA)

• Perfluorobutyrate (PFBA)

• Perfluorobutanesulfonic acid (PFBS)

• Perfluorodecanoic acid (PFDA)

• Perfluorododecanoic acid (PFDoA)

• Perfluoroheptanoic acid (PFHpA)

• Perfluorohexanoic acid (PFHxA)

• Perfluorohexanesulfonic acid (PFHxS)

• Perfluorononanoic acid (PFNA)

• Perfluorooctanoic acid (PFOA)

• Perfluorooctanesulfonic acid (PFOS)

• Perfluoropentanoic acid (PFPeA)

• Perfluorotetradecanoic acid (PFTeDA)

• Perfluorotridecanoic acid (PFTrDA)

• Perfluoroundecanoic acid (PFUdA)

Soil samples were also analyzed for TOC using USEPA Method 9060A and pH by USEPA Method 

9045D.

5.8 Deviations from SI QAPP Addendum

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

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

Corrective Action Report (Appendix B3):

• Upon review of field documentation, it was discovered that an ERB was not collected from 

the hand auger used to collect the surface soil samples (0 to 2 feet below ground surface) 

during the field effort. As a result, the data validation took conservative approach when 

considering the hand auger samples by assuming all results are true positives. Additional 

details are provided in the DUA presented in Section 4.6 of this SI Report. 
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Table 5-1

Site Inspection Samples by Medium

Site Inspection Report, Windsor Locks AASF, Connecticut

Sample Identification

Sample

Collection 

Date/Time

Sample Depth 

(feet bgs)

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

Comments

AOI01-01-SB-00-02 4/27/2021 12:45 0 - 2 x

AOI01-01-SB-05-07 4/27/2021 12:50 5 - 7 x

AOI01-02-SB-00-02 4/27/2021 10:35 0 - 2 x

AOI01-02-SB-04-06 4/27/2021 11:00 4 - 6 x

AOI01-03-SB-00-02 4/29/2021 8:00 0 - 2 x

AOI01-03-SB-03-05 4/29/2021 8:05 3 - 5 x

AOI01-03-SB-05-07 4/29/2021 8:10 5 - 7 x

AOI01-04-SB-00-02 4/29/2021 8:55 0 - 2 x

AOI01-04-SB-03-05 4/29/2021 9:00 3 - 5 x

AOI01-05-SB-00-02 4/28/2021 12:20 0 - 2 x x x

AOI01-05-SB-00-02-D 4/28/2021 12:20 0 - 2 x x FD

AOI01-05-SB-02-04 4/28/2021 12:23 2 - 4 x

AOI01-05-SB-04-06 4/28/2021 12:25 4 - 6 x

AOI01-06-SB-00-02 4/28/2021 9:40 0 - 2 x

AOI01-06-SB-03-05 4/28/2021 10:00 3 - 5 x

AOI01-07-SB-00-02 4/28/2021 8:45 0 - 2 x

AOI01-07-SB-00-02-D 4/28/2021 8:45 0 - 2 x FD

AOI01-07-SB-02-04 4/28/2021 8:50 2 - 4 x

AOI01-07-SB-04-06 4/28/2021 8:55 4 - 6 x

AOI01-08-SB-00-02 4/28/2021 7:50 0 - 2 x

AOI01-08-SB-00-02-MS 4/28/2021 7:50 0 - 2 x MS

AOI01-08-SB-00-02-MSD 4/28/2021 7:50 0 - 2 x MSD

AOI01-08-SB-02-04 4/28/2021 7:55 2 - 4 x

AOI01-08-SB-04-06 4/28/2021 8:00 4 - 6 x

AOI01-09-SB-00-02 4/27/2021 14:00 0 - 2 x

AOI01-09-SB-00-02-D 4/27/2021 14:00 0 - 2 x FD

AOI01-09-SB-05-07 4/27/2021 14:10 5 - 7 x

AOI01-09-SB-08-10 4/27/2021 14:11 8 - 10 x

AOI01-10-SB-00-02 4/28/2021 14:05 0 - 2 x x x

AOI01-10-SB-00-02-D 4/28/2021 14:05 0 - 2 x FD

AOI01-10-SB-00-02-MS 4/28/2021 14:05 0 - 2 x x MS

AOI01-10-SB-00-02-MSD 4/28/2021 14:05 0 - 2 x x MSD

AOI01-10-SB-03-05 4/28/2021 14:10 3 - 5 x

AOI01-10-SB-03-05-MS 4/28/2021 14:10 3 - 5 x MS

AOI01-10-SB-03-05-MSD 4/28/2021 14:10 3 - 5 x MSD

AOI01-01-GW 4/27/2021 15:25 NA x

AOI01-02-GW 4/28/2021 8:50 NA x

AOI01-03-GW 4/29/2021 10:05 NA x

AOI01-03-GW-D 4/29/2021 10:05 NA x FD

AOI01-04-GW 4/29/2021 11:30 NA x

AOI01-05-GW 4/28/2021 14:35 NA x

AOI01-06-GW 4/28/2021 12:45 NA x

AOI01-07-GW 4/28/2021 11:40 NA x

AOI01-08-GW 4/28/2021 10:10 NA x

AOI01-09-GW 4/27/2021 16:20 NA x

AOI01-10-GW 4/29/2021 8:20 NA x

AOI01-10-GW-MS 4/29/2021 8:20 NA x MS

AOI01-10-GW-MSD 4/29/2021 8:20 NA x MSD

Soil Samples

Groundwater Samples

AECOM 5-7
Table 5-1

Site Inspection Samples by Medium

Site Inspection Report, Windsor Locks AASF, Connecticut

Sample Identification

Sample

Collection 

Date/Time

Sample Depth 

(feet bgs)

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

Comments

WL-FRB-01 4/29/2021 7:50 NA x

WL-ERB-01 4/28/2021 13:25 NA x from DPT shoe

WL-ERB-02 4/28/2021 14:30 NA x from DPT shoe

WL-ERB-03 4/29/2021 9:00 NA x from DPT shoe

WL-ERB-04 4/29/2021 10:00 NA x from DPT shoe

Notes:

ASTM = American Society for Testing and Materials

bgs = below ground surface

ERB = equipment rinsate blank

FD = field duplicate

FRB = field reagent blank

LC/MS/MS = Liquid Chromatography Mass Spectrometry

MS/MSD = matrix spike/ matrix spike duplicate

PFAS = per- and polyfluoroalkyl substances

QSM = Quality Systems Manual

TOC = total organic carbon

USEPA = United States Environmental Protection Agency

Quality Control Samples

AECOM 5-8
Table 5-2

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

Site Inspection Report, Windsor Locks AASF, Connecticut

Area of 

Interest

Boring 

Location

Soil Boring 

Depth 

(feet bgs)

Temporary Well 

Screen Interval 

(feet bgs)

Top of Casing 

Elevation 

(feet NAVD88)

Ground Surface 

Elevation 

(feet NAVD88)

Depth to 

Water

(feet btoc)

Dept

Wa

(feet 

AOI01-01 12 7 - 12 161.21 158.06 9.69 6.5AOI01-02 15 6.5 - 11.5 1 157.95 153.72 7.60 3.3

AOI01-03 15 7 - 12 1 153.58 152.95 5.72 5.0AOI01-04 10 5 - 10 153.60 153.11 4.29 3.8AOI01-05 15 6 - 11 1 152.80 152.20 4.73 4.AOI01-06 10 5 - 10 152.55 152.05 4.05 3.5AOI01-07 12 6 - 11 1 160.71 156.20 10.43 5.9

AOI01-08 15 6 - 11 1 161.85 157.32 10.34 5.8AOI01-09 15 10 - 15 171.38 169.15 10.34 8.

AOI01-10 10 5 - 10 155.55 155.05 5.50 5.0

Notes:

1 Temporary well screen set above total depth to capture groundwater interface

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

1

AECOM 
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!?

!?

!?

!?

!?

!?

!?

!?

!?

!?

Windsor Locks Readiness Center

Hazardous Waste Storage Area

Building 200

Wash

Rack

AOI 1 Building 152

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI01-05

AOI01-06

AOI01-07

AOI01-08

AOI01-09

AOI01-10

CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

AM

7/28/2021

7/28/2021

NOTES Site Inspection for PFAS at Windsor Locks AASF, CT

1:3,600

7/28/2021 ­ Figure 5-1

PM CM 7/28/2021

12420 Milestone Center Drive

Germantown, MD 20876

Site Inspection Sample Locations

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

Geographics, CNES/Airbus DS, USDA, USGS,

C:\Users\stankevichm\OneDrive - AECOM Directory\ARNG_PFAS_GIS_60552172\MXDs\CT\Windsor_Locks_AASF_Figures\Windsor_Locks_SI_Figures\SI_Report\Fig_5-1_Windsor_Locks_AASF_SI_Samples.mxd

Legend

!? Soil Boring/Groundwater Location

Area of Interest

Facility Boundary

Wetland

River/Stream

Canal/Ditch

Storm Water Utility Line

0 150 300 600

Feet

AECOM 5-11
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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 AOI 1 is provided in Section 6.3. Table 

6-2 through Table 6-5 present PFAS results for samples with detections in soil and groundwater;

only constituents detected in one or more samples are included. 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 15 October 

2019 (Assistant Secretary of Defense, 2019). 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 three compounds: 

PFOS, PFOA, and PFBS. The SLs were calculated using the USEPA Office of Superfund Sites 

On-Line Calculator, which was updated on 8 April 2021 based on the release of the final Human 

Health Toxicity Values for PFBS (USEPA, 2021). 

Additionally, the USEPA issued drinking water lifetime HAs for PFOA and PFOS in May 2016 

(USEPA 2016a; USEPA, 2016b). The USEPA HAs may also be used as SLs for groundwater 

samples collected at the facility boundary where off-facility drinking water wells are present 

downgradient. The SLs are presented on Table 6-1 below. All other results presented in this report 

are considered informational in nature and serve as an indication as to whether soil and 

groundwater contain or do not contain PFAS within the boundaries of the facility. 

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

Analyte

Residential

(Soil)

(μg/kg)a,b 

0-2 feet bgs

Industrial/ Commercial 

Composite Worker

(Soil)

(μg/kg)a,b 

2-15 feet bgs

Tap Water

(Groundwater) 

(ng/L)a,b

USEPA HA

(Groundwater 

representative of 

Drinking Water)

(ng/L)c,d

PFOA 130 1,600 40 70

PFOS 130 1,600 40 70

PFBS 1,900 25,000 600 - 

Notes:

a.) Assistant Secretary of Defense, 2019. Risk Based Screening Levels Calculated for PFOS, PFOA, PFBS in Groundwater and Soil using 

United States Environmental Protection Agency’s (USEPA’s) Regional Screening Level Calculator. Hazard Quotient (HQ) = 0.1. 15 October 

2019. 

b.) USEPA, 2021. Risk Based Screening Levels Calculated for PFBS in Groundwater and Soil using USEPA’s Regional Screening Level 

Calculator. HQ = 0.1. 8 April 2021.

c.) USEPA. 2016a. Drinking Water HA for Perfluorooctanoic Acid (PFOA). Office of Water (4304T). Health and Ecological Criteria Division, 

Washington, DC 20460. USEPA Document Number: 822-R-16-005. May 2016. / USEPA. 2016b. Drinking Water HA for Perfluorooctane 

Sulfonic Acid (PFOS). Office of Water (4304T). Health and Ecological Criteria Division, Washington, DC 20460. USEPA Document Number: 

822-R-16-004. May 2016.

d.) USEPA HAs apply to the PFOA and PFOS concentrations individually or combined.

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

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

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

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

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

Army Aviation Support Facility, Windsor Locks, Connecticut

AECOM 6-2

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.

6.2 Soil Physicochemical Analyses

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

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

of the TOC and pH sampling. 

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

appropriate, to assess fate and transport of PFAS contaminants. According to the Interstate 

Technology Regulatory Council (ITRC), several important PFAS partitioning mechanisms include 

hydrophobic and lipophobic effects, electrostatic interactions, and interfacial behaviors. At 

relevant environmental pH values, certain PFAS are present as organic anions and are therefore 

relatively mobile in groundwater (Xiao et al., 2015), but tend to associate with the organic carbon 

fraction that may be present in soil or sediment (Higgins and Luthy, 2006; Guelfo and Higgins, 

2013). When sufficient organic carbon is present, organic carbon normalized distribution 

coefficients (Koc values) can help in evaluating transport potential, though other geochemical 

factors (for example, pH and presence of polyvalent cations) may also affect PFAS sorption to 

solid phases (ITRC, 2018).

6.3 AOI 1 

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

1, which includes two potential PFAS release areas: the Wash Rack and Building 152. The 

detected compounds in soil and groundwater are summarized on Table 6-2 through Table 6-4. 

The detections of PFOA, PFOS, and PFBS in soil and groundwater are presented on Figure 6-1

through Figure 6-4. 

6.3.1 AOI 1 Soil Analytical Results

PFOA, PFOS, and PFBS did not exceed the SLs in soil at any sample locations at the facility. 

Figure 6-1 through Figure 6-3 present detections in soil for PFOA, PFOS, and PFBS. Table 6-2 

through Table 6-4 summarize the detected compounds in soil. 

During the SI, soil samples were collected from the surface soil (0 to 2 feet bgs) and shallow 

subsurface soil (2 to 10 feet bgs) at depths above the groundwater table. PFOA was detected in 

surface soil at three of the ten (10) locations, at concentrations ranging from 0.155 J micrograms 

per kilogram (μg/kg) to 0.200 J μg/kg. The maximum detection of PFOA in surface soil occurred 

at AOI01-09, which is located along the southern facility boundary and is considered upgradient 

of the two potential PFAS release areas (Wash Rack and Building 152). PFOA was detected in 

shallow subsurface soil at four of the ten (10) locations, at concentrations ranging from 0.106 J+ 

μg/kg to 0.491 J μg/kg. The maximum detection of PFOA in shallow subsurface soil occurred at 

AOI01-03 (5 to 7 feet bgs), which is located to the east of the drainage swale along the edge of 

the facility parking lot.

PFOS was detected in surface soil at all 10 locations, at concentrations ranging from 0.445 J 

μg/kg to 4.28 J+ μg/kg. PFOS was also detected in shallow subsurface soil at nine of the ten (10) 

locations (in at least one sample), at concentrations ranging from 0.169 J μg/kg to 41.5 μg/kg. 

The maximum detections of PFOS in both surface soil and shallow subsurface soil (2 to 4 feet 

bgs) occurred at AOI01-08, which corresponds to the location of the maximum detection of PFOS 

in groundwater (see Section 6.3.2). AOI01-08 is located on the western side of the facility’s 

tarmac. No potential PFAS release areas were identified during the PA in the immediate vicinity 

of this sample location. It was noted during the TPP 1&2 (21 December 2020) that there were six 

to ten (10) mobile units periodically parked in various spots on the flight deck beside flight 
Site Inspection Report

Army Aviation Support Facility, Windsor Locks, Connecticut

AECOM 6-3

machines (helicopters/planes); however, there were no documented discharges from mobile units 

onto the flight deck. 

PFBS was detected in surface soil at three of the ten (10) locations, at concentrations ranging 

from 0.139 J μg/kg to 0.177 J μg/kg. PFBS was detected in shallow subsurface soil at two of the 

ten (10) locations, at concentrations ranging from 0.117 J μg/kg to 0.162 J μg/kg. The maximum 

detections of PFBS in both surface soil and shallow subsurface soil occurred at AOI01-01, which 

is located in the southern portion of the facility upgradient of the identified potential PFAS release 

areas. 

At location AOI01-02, which was located immediately downgradient of the Wash Rack potential 

PFAS release area, PFOS was detected in surface and shallow subsurface soil (3.82 μg/kg and 

1.89 μg/kg, respectively), and PFBS was detected in surface soil (0.163 J μg/kg). At location 

AOI01-04, which was located immediately downgradient of the Building 152 potential PFAS 

release area, PFOS was detected in surface and shallow subsurface soil (2.60 μg/kg and 0.310 

J+ μg/kg). The detections of PFOS and PFBS at these locations indicate there was likely a release 

of PFAS-containing materials at both the Wash Rack and Building 152 potential release areas; 

however, the detections were several orders of magnitude below the SLs. 

6.3.2 AOI 1 Groundwater Analytical Results

PFOA and PFOS in groundwater exceeded the individual SLs of 40 nanograms per liter (ng/L) at 

both potential PFAS release areas, Wash Rack (AOI01-02) and Building 152 (AOI01-04). 

Additionally, PFOA and PFOS in groundwater exceeded the SLs at upgradient location AOI01-01, 

located in the southern portion of the facility, and at location AOI01-03, located to the east of the 

drainage swale along the edge of the facility parking lot. PFOA in groundwater also exceeded the 

SL at AOI01-05, located on the northern side of Building 200, near the stormwater outfall that 

connects to drains from both Building 152 and 200. PFOS in groundwater exceeded the SL at

upgradient locations AOI01-07, AOI01-08, and AOI01-09 along the western and southern facility 

boundaries. PFBS did not exceed the SL at AOI 1. Figure 6-4 presents the ranges of detections 

of PFOA, PFOS, and PFBS in groundwater. Table 6-4 summarizes the detected compounds in 

groundwater. 

PFOA was detected in groundwater at all 10 locations across AOI 1, at concentrations ranging 

from 5.45 ng/L to 298 ng/L. The detected concentrations of PFOA exceeded the OSD SL of 40 

ng/L at five locations (AOI01-01 through AOI01-05) and the USEPA HA of 70 ng/L at three 

locations (AOI01-03 through AOI01-05). The maximum detection of PFOA occurred at AOI01-03-

GW, which is located to the east of the drainage swale along the edge of the facility parking lot. 

No potential PFAS release areas were identified during the PA in the immediate vicinity of this 

sample location. Although a common fire training activity is to discharge mobile fire extinguisher 

units along the edges of parking lots, there were no documented discharges from mobile units in 

the facility parking lot during the PA or SI planning phase. Additionally, the stormwater outfall 

where the stormwater detention system flows into the eastern drainage swale is located 

approximately 50 feet southwest of AOI01-03. 

Alternatively, based on the groundwater elevations collected during the SI (Figure 2-5), 

groundwater flow east of the drainage swale is towards the drainage swale (to the westsouthwest); therefore, there is also the potential that the detected concentrations of PFOA, PFOS, 

and PFBS at AOI01-03 may be flowing onto the facility from an unidentified upgradient, offsite 

source to the east of the facility. Potential offsite, adjacent sources identified in the PA Report 

(AECOM, 2020) and SI QAPP Addendum (AECOM, 2021a) are shown on Figure 3-1. No 

potential offsite, adjacent sources have been identified to the east of the facility at the time of this 

report.
Site Inspection Report

Army Aviation Support Facility, Windsor Locks, Connecticut

AECOM 6-4

PFOS was detected in groundwater at nine of the ten (10) locations, at concentrations ranging 

from 8.93 ng/L to 581 ng/L. The detected concentrations of PFOS exceeded the OSD SL of 40 

ng/L at seven locations (all locations except AOI01-05, AOI01-06, and AOI01-10) and the USEPA 

HA of 70 ng/L at six locations (all locations except AOI01-05, AOI01-06, AOI01-07, and AOI01-

10). The maximum detection of PFOS in groundwater occurred at AOI01-08-GW, which is located 

on the western side of the facility’s tarmac. As described above in Section 6.3.1, no potential 

PFAS release areas were identified during the PA in the immediate vicinity of this sample location; 

however, it was noted during the TPP 1&2 (21 December 2020) that there were six to ten (10) 

mobile units periodically parked in various spots on the flight deck beside flight machines 

(helicopters/planes). There were no documented discharges from mobile units onto the flight 

deck. Based on the groundwater elevations collected during the SI (Figure 2-5), groundwater flow 

west of the drainage swale is generally to the northeast towards the drainage swale; therefore, 

there is also the potential that PFOA, PFOS, and PFBS may be flowing onto the facility from an 

upgradient, offsite source to the west of the facility (Figure 3-1). 

PFBS was detected in groundwater at nine of the ten (10) locations, at concentrations below the 

OSD SL of 600 ng/L. The detected concentrations of PFBS ranged from 1.33 J ng/L to 51.3 ng/L. 

Similar to the results of PFOA in groundwater, the maximum detection of PFBS occurred at AOI01-

03-GW, which is located to the east of the drainage swale, as described above.

At location AOI01-02, which was located immediately downgradient of the Wash Rack potential 

PFAS release area, PFOA and PFOS were detected at concentrations exceeding the SLs (40.5 

ng/L and 94.2 ng/L, respectively). PFBS was detected at a concentration below SLs (4.15 ng/L). 

At location AOI01-04, which was located immediately downgradient of the Building 152 potential 

PFAS release area, PFOA and PFOS were detected at concentrations exceeding the SLs (71.8 

ng/L and 408 ng/L, respectively). PFBS was detected at a concentration below SLs (19.4 ng/L). 

Based on the results of the SI for groundwater at these locations, in combination with the 

detections in soil, it is likely that releases occurred at the Wash Rack and Building 152 release 

areas. However, based on the exceedances of PFOA and PFOS in groundwater at locations along 

the facility boundary (AOI01-07, AOI01-08, and AOI01-09), there is also the potential that releases 

from off-facility, adjacent sources could be migrating onto the facility.

6.3.3 AOI 1 Conclusions

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

there was likely a release of PFAS-containing materials; however, the detected concentrations 

were several orders of magnitude lower than the soil SLs. PFOA and PFOS in groundwater 

exceeded the individual SLs of 40 ng/L at both potential PFAS release areas, Wash Rack (AOI01-

02) and Building 152 (AOI01-04); at AOI01-01, located in the southern portion of the facility; and

at AOI01-03, located east of the drainage swale along the edge of the facility parking lot. PFOA

in groundwater also exceeded the SL at AOI01-05, on the north side of Building 200. PFOS in

groundwater also exceeded the SL at upgradient locations AOI01-07, AOI01-08, and AOI01-09

along the western and southern facility boundaries. PFBS was detected in groundwater at

concentrations below the SL. Based on the results of the SI, it is likely that releases occurred on

the facility property. However, based on the exceedances along the upgradient facility boundary,

it is also likely that releases from off-facility, adjacent sources are migrating onto the facility. Due

to the exceedances of the SLs for PFOA and PFOS in groundwater, further evaluation of AOI 1 is

warranted.
Table 6-2

PFAS Detections in Surface Soil

Site Inspection Report, Windsor Locks AASF, Connecticut

Analyte OSD Screening 

Level a,b

Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Q

6:2 FTS - ND 0.149 J ND ND ND ND ND ND ND 

8:2 FTS - ND 0.197 J ND ND ND ND ND ND ND 

NEtFOSAA - ND ND 0.039 J+ ND ND ND ND ND ND 

PFBA - 0.054 J 0.089 J 0.093 J 0.048 J ND 0.235 J 0.096 J 0.069 J 0.109 J PFBS 1900 0.177 J 0.163 J ND ND ND ND ND ND ND 

PFDA - ND 0.432 J 0.366 J 0.076 J ND 0.116 J 0.183 J 0.116 J 0.082 J PFDoA - ND 0.561 J 0.134 J 0.029 J 0.092 J 0.023 J 0.023 J 0.022 J 0.046 J 

PFHpA - ND 0.045 J 0.031 J ND ND 0.100 J 0.026 J 0.026 J 0.049 J 

PFHxA - 0.026 J 0.096 J 0.127 J ND ND 0.121 J ND ND 0.087 J 

PFHxS - 0.127 J 0.576 J 0.856 J 0.412 J 0.110 J ND 0.068 J 0.059 J 0.217 J PFNA - ND 0.145 J 0.135 J 0.043 J ND 0.120 J 0.114 J 0.070 J 0.039 J PFOA 130 ND ND ND ND ND 0.173 J ND ND 0.155 J 

PFOS 130 1.01 J 3.82 2.86 2.60 0.515 J 0.445 J 0.970 J 1.18 4.28 J+ 

PFPeA - ND 0.124 J 0.087 J 0.047 J ND 0.189 J 0.031 J 0.031 J 0.098 J PFTeDA - ND 0.211 J 0.054 J ND 0.063 J ND ND ND ND 

PFTrDA - ND 3.16 1.56 ND 0.313 J 0.082 J 0.035 J 0.035 J 0.067 J 

PFUnDA - 0.032 J 5.05 1.51 0.053 J 0.451 J 0.051 J 0.076 J 0.055 J 0.282 J 

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

6:2 FTS 6:2 fluorotelomer sulfonate8:2 FTS 8:2 fluorotelomer sulfonateNEtFOSAA N-ethyl perfluorooctane- sulfonamidoacetic acid

References PFBA perfluorobutanoic acid

PFBS perfluorobutanesulfonic acidPFDA perfluorodecanoic acidPFDoA perfluorododecanoic acidPFHpA perfluoroheptanoic acidPFHxA perfluorohexanoic acidPFHxS perfluorohexanesulfonic acidPFNA perfluorononanoic acid

Interpreted Qualifiers PFOA perfluorooctanoic acid

J = Estimated concentration PFOS perfluorooctanesulfonic acid

J+ = Estimated concentration, biased high PFPeA perfluoropentanoic acid

UJ = The analyte was not detected at a level greater than or equal to the adjusted detection limit (DL). However, the reported adjusted DL is approximate and may be inaccurate or imprecise. PFTeDA perfluorotetradecanoic acid

PFTrDA perfluorotridecanoic acidPFUnDA perfluoro-n-undecanoic acidAcronyms and Abbreviations

AASF Army Aviation Support FacilityAOI Area of InterestD duplicateft feetHQ hazard quotientLCMSMS liquid chromatography with tandem mass spectroLOD limit of detectionND analyte not detected above the LODOSD Office of the Secretary of DefenseQSM Quality Systems ManualQual interpreted qualifierSB soil boringUSEPA United States Environmental Protection Agencyμg/kg micrograms per kilogram- not applicable

Area of Interest

Sample ID

Sample Date

Depth

AOI01-01-SB-00-02

04/27/2021

0 - 2 ft

AOI01-02-SB-00-02

04/27/2021

0 - 2 ft

AOI01-03-SB-00-02

04/29/2021

0 - 2 ft

AOI01-07-SB-00-02

04/28/2021

0 - 2 ft

AOI01-04-SB-00-02

04/29/2021

0 - 2 ft

AOI01-05-SB-00-02

04/28/2021

0 - 2 ft

a. Assistant Secretary of Defense, 2019. Risk Based Screening Levels Calculated for PFOS and PFOA in Groundwater or Soil using USEPA’s Regional Screening Level Calculator. HQ=0.1. 15 October 2019. Soil screening levels based on residential scenario for direct ingestion of contaminated soil.b. USEPA, 2021. Risk Based Screening Levels Calculated for PFBS in Groundwater and Soil using USEPA's Regional Screening Level Calculator. HQ=0.1. 8 April 2021.

AOI01

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

AOI01-07-SB-00-02-D

04/28/2021

0 - 2 ft

AOI01-08-SB-0

04/28/2021

0 - 2 ft

AOI01-06-SB-00-02

04/28/2021

0 - 2 ft

AECOM 
Table 6-2

PFAS Detections in Surface Soil

Site Inspection Report, Windsor Locks AASF, Connecticut

Analyte OSD Screening 

Level a,b

Result Qual Result Qual Result Qual

6:2 FTS - ND ND ND8:2 FTS - ND ND NDNEtFOSAA - ND ND NDPFBA - 0.149 J 0.065 J 0.058 JPFBS 1900 0.137 J ND ND

PFDA - 0.070 J 0.324 J 0.290 JPFDoA - 0.027 J 0.099 J 0.102 JPFHpA - 0.056 J 0.023 J ND UJPFHxA - 0.108 J 0.080 J 0.068 JPFHxS - 0.261 J 0.377 J 0.311 JPFNA - 0.111 J ND UJ 0.053 JPFOA 130 0.139 J ND ND

PFOS 130 1.77 2.00 1.79

PFPeA - 0.107 J 0.044 J 0.035 JPFTeDA - ND 0.039 J 0.032 J

PFTrDA - 0.124 J 0.475 J 0.509 JPFUnDA - 0.120 J 1.27 1.30

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

6:2 FTS 6:2 fluorotelomer sulfonate8:2 FTS 8:2 fluorotelomer sulfonateNEtFOSAA N-ethyl perfluorooctane- sulfonamidoacetic acid

References PFBA perfluorobutanoic acid

PFBS perfluorobutanesulfonic acidPFDA perfluorodecanoic acidPFDoA perfluorododecanoic acidPFHpA perfluoroheptanoic acidPFHxA perfluorohexanoic acidPFHxS perfluorohexanesulfonic acidPFNA perfluorononanoic acid

Interpreted Qualifiers PFOA perfluorooctanoic acid

J = Estimated concentration PFOS perfluorooctanesulfonic acid

J+ = Estimated concentration, biased high PFPeA perfluoropentanoic acid

UJ = The analyte was not detected at a level greater than or equal to the adjusted detection limit (DL). However, the reported adjusted DL is approximate and may be inaccurate or imprecise. PFTeDA perfluorotetradecanoic acid

PFTrDA perfluorotridecanoic acidPFUnDA perfluoro-n-undecanoic acidAcronyms and Abbreviations

AASF Army Aviation Support FacilityAOI Area of InterestD duplicateft feetHQ hazard quotientLCMSMS liquid chromatography with tandem mass spectroLOD limit of detectionND analyte not detected above the LODOSD Office of the Secretary of DefenseQSM Quality Systems ManualQual interpreted qualifierSB soil boringUSEPA United States Environmental Protection Agencyμg/kg micrograms per kilogram- not applicable

0 - 2 ft

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

a. Assistant Secretary of Defense, 2019. Risk Based Screening Levels Calculated for PFOS and PFOA in Groundwater or Soil using USEPA’s Regional Screening Level Calculator. HQ=0.1. 15 October 2019. Soil screening levels based on residential scenario for direct ingestion of contaminated soil.b. USEPA, 2021. Risk Based Screening Levels Calculated for PFBS in Groundwater and Soil using USEPA's Regional Screening Level Calculator. HQ=0.1. 8 April 2021.

Area of Interest

Sample ID

Sample Date

Depth

AOI01-09-SB-00-02-D

AOI01

AOI01-10-SB-00-02

04/28/2021

0 - 2 ft

AOI01-10-SB-00-02-D

04/28/2021

0 - 2 ft

04/27/2021

AECOM 
Table 6-3

PFAS Detections in Shallow Subsurface Soil

Site Inspection Report, Windsor Locks AASF, Connecticut

Analyte OSD Screening 

Level a,b

Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Resu

Soil, PFAS by LCMSMS compliant with QSM 5.3 Table B-15 (μg/kg)6:2 FTS - ND ND ND ND ND ND ND ND ND 8:2 FTS - ND 0.070 J ND ND ND ND ND ND ND 

PFBA - 0.045 J 0.061 J 0.055 J 0.141 J ND ND ND ND ND PFBS 25000 0.162 J ND ND ND ND ND ND ND ND PFDA - ND 0.675 J 0.346 J 0.230 J ND ND ND ND ND PFDoA - ND ND 0.115 J 0.047 J ND 0.032 J ND ND ND 

PFHpA - ND 0.064 J 0.181 J 0.093 J ND ND ND ND ND PFHxA - ND 0.077 J 0.316 J 0.530 J ND ND ND 0.039 J ND 

PFHxS - ND 0.148 J 4.86 7.56 0.129 J 0.058 J ND ND ND 

PFNA - ND 0.150 J 0.169 J 0.170 J ND 0.023 J ND ND ND 

PFOA 1600 ND ND 0.278 J 0.491 J ND ND ND ND ND 

PFOS 1600 0.582 J 1.89 5.07 6.19 0.310 J+ 0.196 J 0.300 J ND 0.169 

PFPeA - ND 0.066 J 0.055 J 0.096 J ND 0.023 J ND ND ND 

PFTeDA - ND ND UJ 0.034 J ND ND 0.022 J ND ND ND PFTrDA - ND ND UJ 1.42 0.539 J ND 0.098 J ND ND ND PFUnDA - ND 1.35 8.02 3.31 ND 0.162 J ND ND ND 

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

6:2 FTS 6:2 fluorotelomer sulfonate8:2 FTS 8:2 fluorotelomer sulfonatePFBA perfluorobutanoic acid

References PFBS perfluorobutanesulfonic acid

PFDA perfluorodecanoic acidPFDoA perfluorododecanoic acidPFHpA perfluoroheptanoic acidPFHxA perfluorohexanoic acidPFHxS perfluorohexanesulfonic acidPFNA perfluorononanoic acidPFOA perfluorooctanoic acid

Interpreted Qualifiers PFOS perfluorooctanesulfonic acidJ = Estimated concentration PFPeA perfluoropentanoic acid

J+ = Estimated concentration, biased high PFTeDA perfluorotetradecanoic acid

UJ = The analyte was not detected at a level greater than or equal to the adjusted detection limit (DL). However, the reported adjusted DL is approximate and may be inaccurate or imprecise. PFTrDA perfluorotridecanoic acid

PFUnDA perfluoro-n-undecanoic acidAcronyms and Abbreviations

AASF Army Aviation Support FacilityAOI Area of Interestft feetHQ hazard quotientLCMSMS liquid chromatography with tandem mLOD limit of detectionND analyte not detected above the LODOSD Office of the Secretary of DefenseQSM Quality Systems ManualQual interpreted qualifierSB soil boringUSEPA United States Environmental Protectioμg/kg micrograms per kilogram- not applicable

a. Assistant Secretary of Defense, 2019. Risk Based Screening Levels Calculated for PFOS and PFOA in Groundwater or Soil using USEPA’s Regional Screening Level Calculator. HQ=0.1. 15 October 2019. Soil screening levels based on industrial/commercial composite worker scenario for incidental ingestion of contaminated soil.b. USEPA, 2021. Risk Based Screening Levels Calculated for PFBS in Groundwater and Soil using USEPA's Regional Screening Level Calculator. HQ=0.1. 8 April 2021.

AOI01

AOI01-06-SB-03-05

04/28/2021

3 - 5 ft

AOI01

04

AOI01-05-SB-02-04

04/28/2021

2 - 4 ft

AOI01-05-SB-04-06

04/28/2021

4 - 6 ft

AOI01-03-SB-05-07

04/29/2021

5 - 7 ft

AOI01-04-SB-03-05

04/29/2021

3 - 5 ft

AOI01-02-SB-04-06

04/27/2021

4 - 6 ft

AOI01-03-SB-03-05

04/29/2021

3 - 5 ft

Area of Interest

Sample ID

Sample Date

Depth

AOI01-01-SB-05-07

04/27/2021

5 - 7 ft

AECOM 
Table 6-3

PFAS Detections in Shallow Subsurface Soil

Site Inspection Report, Windsor Locks AASF, Connecticut

Analyte OSD Screening 

Level a,b

Result Qual Result Qual Result Qual Result Qual Result Qual

6:2 FTS - ND 0.214 J ND ND ND

8:2 FTS - ND ND ND ND ND

PFBA - ND ND ND ND 0.066 J

PFBS 25000 ND ND 0.117 J 0.145 J ND

PFDA - 0.057 J ND ND ND NDPFDoA - ND ND ND ND ND

PFHpA - 0.030 J ND ND ND 0.033 J

PFHxA - ND 0.119 J 0.035 J ND 0.089 JPFHxS - 0.061 J ND 0.039 J 0.081 J 0.297 J+

PFNA - 0.164 J ND 0.026 J ND 0.141 J

PFOA 1600 0.285 J ND ND ND 0.106 J+

PFOS 1600 41.5 ND 0.441 J ND 0.795 J

PFPeA - 0.027 J ND ND ND 0.043 J

PFTeDA - ND ND ND ND ND

PFTrDA - ND ND ND ND ND

PFUnDA - ND ND ND ND ND

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

6:2 FTS 6:2 fluorotelomer sulfonate8:2 FTS 8:2 fluorotelomer sulfonatePFBA perfluorobutanoic acid

References PFBS perfluorobutanesulfonic acid

PFDA perfluorodecanoic acidPFDoA perfluorododecanoic acidPFHpA perfluoroheptanoic acidPFHxA perfluorohexanoic acidPFHxS perfluorohexanesulfonic acidPFNA perfluorononanoic acidPFOA perfluorooctanoic acid

Interpreted Qualifiers PFOS perfluorooctanesulfonic acidJ = Estimated concentration PFPeA perfluoropentanoic acid

J+ = Estimated concentration, biased high PFTeDA perfluorotetradecanoic acid

UJ = The analyte was not detected at a level greater than or equal to the adjusted detection limit (DL). However, the reported adjusted DL is approximate and may be inaccurate or imprecise. PFTrDA perfluorotridecanoic acid

PFUnDA perfluoro-n-undecanoic acidAcronyms and Abbreviations

AASF Army Aviation Support FacilityAOI Area of Interestft feetHQ hazard quotientLCMSMS liquid chromatography with tandem mLOD limit of detectionND analyte not detected above the LODOSD Office of the Secretary of DefenseQSM Quality Systems ManualQual interpreted qualifierSB soil boringUSEPA United States Environmental Protectioμg/kg micrograms per kilogram- not applicable

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

a. Assistant Secretary of Defense, 2019. Risk Based Screening Levels Calculated for PFOS and PFOA in Groundwater or Soil using USEPA’s Regional Screening Level Calculator. HQ=0.1. 15 October 2019. Soil screening levels based on industrial/commercial composite worker scenario for incidental ingestion of contaminated soil.b. USEPA, 2021. Risk Based Screening Levels Calculated for PFBS in Groundwater and Soil using USEPA's Regional Screening Level Calculator. HQ=0.1. 8 April 2021.

AOI01

AOI01-09-SB-08-10

04/27/2021

8 - 10 ft

AOI01-10-SB-03-05

04/28/2021

3 - 5 ft

AOI01-08-SB-04-06

04/28/2021

4 - 6 ft

AOI01-09-SB-05-07

04/27/2021

5 - 7 ft

Area of Interest

Sample ID

Sample Date

Depth

AOI01-08-SB-02-04

04/28/2021

2 - 4 ft

AECOM 
Table 6-4

PFAS Detections in Groundwater

Site Inspection Report, Windsor Locks AASF, Connecticut

Analyte OSD Screening 

Level a,b

USEPA HA c Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result 

6:2 FTS - - 9.38 534 6.77 6.06 64.4 4.46 ND ND 

8:2 FTS - - 10.4 16.9 12.6 10.7 48.2 ND ND ND 

NMeFOSAA - - ND ND 2.69 J 2.17 J 1.000 J ND ND ND 

PFBA - - 29.6 58.1 21.9 22.0 24.6 ND ND ND 

PFBS 600 - 8.75 4.15 51.3 46.5 19.4 15.4 1.65 J ND 

PFDA - - 7.66 1.78 J 3.81 J 3.26 J 3.42 J 1.12 J ND ND 

PFHpA - - 55.4 57.0 16.3 15.0 35.9 9.78 4.74 2.65 J 

PFHxA - - 92.3 169 345 320 95.2 70.9 7.58 3.09 

PFHxS - - 252 127 1830 1350 306 169 13.1 7.07 

PFNA - - 290 32.3 49.7 45.1 97.5 14.7 2.03 J 3.61 J 

PFOA 40 70 57.3 40.5 298 275 71.8 87.2 7.85 5.45 

PFOS 40 70 138 94.2 125 115 408 ND 8.93 52.6 

PFPeA - - 88.5 263 45.0 41.8 82.6 23.0 4.72 2.52 J 

PFUnDA - - 223 ND 52.3 44.7 9.74 ND ND ND 

Total PFOA+PFOS - 70 195.3 134.7 423 390 479.8 87.2 16.78 58.05 

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical AbbreviationsBold Font Detected concentration exceeded USEPA HA Screening Levels 6:2 FTS 6:2 fluorotelomer sulfonate

8:2 FTS 8:2 fluorotelomer sulfonateNMeFOSAA N-methyl perfluorooctanesulfo

References PFBA perfluorobutanoic acid

PFBS perfluorobutanesulfonic acidPFDA perfluorodecanoic acidPFHpA perfluoroheptanoic acidPFHxA perfluorohexanoic acidPFHxS perfluorohexanesulfonic acidPFNA perfluorononanoic acidPFOA perfluorooctanoic acid

Interpreted Qualifiers PFOS perfluorooctanesulfonic acidJ = Estimated concentration PFPeA perfluoropentanoic acid

PFUnDA perfluoro-n-undecanoic acidAcronyms and AbbreviationsAASF Army Aviation Support FacilitAOI Area of InterestD duplicateGW groundwaterHA health advisoryHQ hazard quotientLCMSMS liquid chromatography with taLOD limit of detectionND analyte not detected above thOSD Office of the Secretary of DefQSM Quality Systems ManualQual interpreted qualifierUSEPA United States Environmental ng/L nanogram per liter- not applicable

Area of Interest

Sample ID

Sample Date

AOI01-01-GW

04/27/2021 04/29/2021

AOI01-02-GW

04/28/2021

AOI01-03-GW

04/29/2021

Water, PFAS by LCMSMS compliant with QSM 5.3 Table B-15 (ng/L)

a. Assistant Secretary of Defense, 2019. Risk Based Screening Levels Calculated for PFOS and PFOA in Groundwater or Soil using USEPA’s Regional Screening Level Calculator. HQ=0.1. 15 October 2019. Groundwater screening levels based on residential scenario for direct ingestion of groundwater.b. USEPA, 2021. Risk Based Screening Levels Calculated for PFBS in Groundwater and Soil using USEPA's Regional Screening Level Calculator. HQ=0.1. 8 April 2021.c. USEPA, 2016. Drinking Water Health Advisory for PFOA. Office of Water (4304T). Health and Ecological Criteria Division, Washington, DC 20460. EPA Document Number: 822-R-16-005. May 2016. / EPA. 2016. Drinking Water Health Advisory for PFOS. Office of Water (4304T). Health and Ecological Criteria Division, Washington, DC 20460. EPA Document Number: 822-R-16-004. May 2016.

AOI01

AOI01-0

04/28/

AOI01-05-GW

04/28/2021

AOI01-06-GW

04/28/2021

AOI01-03-GW-D

04/29/2021

AOI01-04-GW

AECOM 
Table 6-4

PFAS Detections in Groundwater

Site Inspection Report, Windsor Locks AASF, Connecticut

Analyte OSD Screening 

Level a,b

USEPA HA c Result Qual Result Qual

6:2 FTS - - ND ND

8:2 FTS - - ND ND

NMeFOSAA - - ND NDPFBA - - 15.9 ND

PFBS 600 - 5.16 3.21 JPFDA - - ND NDPFHpA - - 10.5 3.42 JPFHxA - - 39.5 8.28PFHxS - - 161 60.6PFNA - - 4.25 NDPFOA 40 70 24.6 11.5

PFOS 40 70 399 9.88

PFPeA - - 11.2 3.37 JPFUnDA - - ND NDTotal PFOA+PFOS - 70 423.6 21.38

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical AbbreviationsBold Font Detected concentration exceeded USEPA HA Screening Levels 6:2 FTS 6:2 fluorotelomer sulfonate

8:2 FTS 8:2 fluorotelomer sulfonateNMeFOSAA N-methyl perfluorooctanesulfo

References PFBA perfluorobutanoic acid

PFBS perfluorobutanesulfonic acidPFDA perfluorodecanoic acidPFHpA perfluoroheptanoic acidPFHxA perfluorohexanoic acidPFHxS perfluorohexanesulfonic acidPFNA perfluorononanoic acidPFOA perfluorooctanoic acid

Interpreted Qualifiers PFOS perfluorooctanesulfonic acidJ = Estimated concentration PFPeA perfluoropentanoic acid

PFUnDA perfluoro-n-undecanoic acidAcronyms and AbbreviationsAASF Army Aviation Support FacilitAOI Area of InterestD duplicateGW groundwaterHA health advisoryHQ hazard quotientLCMSMS liquid chromatography with taLOD limit of detectionND analyte not detected above thOSD Office of the Secretary of DefQSM Quality Systems ManualQual interpreted qualifierUSEPA United States Environmental ng/L nanogram per liter- not applicable

b. USEPA, 2021. Risk Based Screening Levels Calculated for PFBS in Groundwater and Soil using USEPA's Regional Screening Level Calculator. HQ=0.1. 8 April 2021.c. USEPA, 2016. Drinking Water Health Advisory for PFOA. Office of Water (4304T). Health and Ecological Criteria Division, Washington, DC 20460. EPA Document Number: 822-R-16-005. May 2016. / EPA. 2016. Drinking Water Health Advisory for PFOS. Office of Water (4304T). Health and Ecological Criteria Division, Washington, DC 20460. EPA Document Number: 822-R-16-004. May 2016.

AOI01

AOI01-10-GW

04/29/2021

Water, PFAS by LCMSMS compliant with QSM 5.3 Table B-15 (ng/L)

a. Assistant Secretary of Defense, 2019. Risk Based Screening Levels Calculated for PFOS and PFOA in Groundwater or Soil using USEPA’s Regional Screening Level Calculator. HQ=0.1. 15 October 2019. Groundwater screening levels based on residential scenario for direct ingestion of groundwater.

Area of Interest

Sample ID

Sample Date

AOI01-09-GW

04/27/2021

AECOM 
AOI01-01

AOI01-02

AOI01-03 AOI01-04

AOI01-05

AOI01-06

AOI01-07

AOI01-08

AOI01-09

AOI01-10

Legend

Facility Boundary

Storm Water Utility Line

AOI01-03

AOI01-05

AOI01-07

AOI01-08

AOI01-09

AOI01-01

AOI01-02

AOI01-03 AOI01-04

AOI01-05

AOI01-06

AOI01-07

AOI01-08

AOI01-09

AOI01-10

­ Figure 6-1

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection for PFAS at Windsor Locks AASF, CT

6/24/2021

6/24/2021

6/24/2021

MS

AM

CM

GIS BY

CHK BY

PM

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

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

6/24/2021

1:4,859

C:\Users\stankevichm\OneDrive - AECOM Directory\ARNG_PFAS_GIS_60552172\MXDs\CT\Windsor_Locks_AASF_Figures\Windsor_Locks_SI_Figures\SI_Report\Results\Fig_6-1_Windsor_Locks_AASF_SI_Soil_PFOA_Results.mxd

Site Inspection PFOA Soil Results

12420 Milestone Center Drive

Germantown, MD 20876

Shallow Intermediate Deep

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

PFOA Results (μg/Kg)

ND

>ND - 10

>10 - 130

>130 - 1,600

>1,600

0 200 400 800

Feet

AECOM 6-11
AOI01-01

AOI01-02

AOI01-03 AOI01-04

AOI01-05

AOI01-06

AOI01-07

AOI01-08

AOI01-09

AOI01-10

Legend

Facility Boundary

Storm Water Utility Line

AOI01-03

AOI01-05

AOI01-07

AOI01-08

AOI01-09

AOI01-01

AOI01-02

AOI01-03 AOI01-04

AOI01-05

AOI01-06

AOI01-07

AOI01-08

AOI01-09

AOI01-10

­ Figure 6-2

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection for PFAS at Windsor Locks AASF, CT

6/24/2021

6/24/2021

6/24/2021

MS

AM

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GIS BY

CHK BY

PM

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

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

6/24/2021

1:4,859

C:\Users\stankevichm\OneDrive - AECOM Directory\ARNG_PFAS_GIS_60552172\MXDs\CT\Windsor_Locks_AASF_Figures\Windsor_Locks_SI_Figures\SI_Report\Results\Fig_6-2_Windsor_Locks_AASF_SI_Soil_PFOS_Results.mxd

Site Inspection PFOS Soil Results

12420 Milestone Center Drive

Germantown, MD 20876

Shallow Intermediate Deep

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

PFOS Results (μg/Kg)

ND

>ND - 10

>10 - 130

>130 - 1,600

>1,600

0 200 400 800

Feet

AECOM 6-1
AOI01-01

AOI01-02

AOI01-03 AOI01-04

AOI01-05

AOI01-06

AOI01-07

AOI01-08

AOI01-09

AOI01-10

Legend

Facility Boundary

Storm Water Utility Line

AOI01-03

AOI01-05

AOI01-07

AOI01-08

AOI01-09

AOI01-01

AOI01-02

AOI01-03 AOI01-04

AOI01-05

AOI01-06

AOI01-07

AOI01-08

AOI01-09

AOI01-10

­ Figure 6-3

CLIENT

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SCALE

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ARNG

Site Inspection for PFAS at Windsor Locks AASF, CT

6/24/2021

6/24/2021

6/24/2021

MS

AM

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

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

6/24/2021

1:4,859

C:\Users\stankevichm\OneDrive - AECOM Directory\ARNG_PFAS_GIS_60552172\MXDs\CT\Windsor_Locks_AASF_Figures\Windsor_Locks_SI_Figures\SI_Report\Results\Fig_6-3_Windsor_Locks_AASF_SI_Soil_PFBS_Results.mxd

Site Inspection PFBS Soil Results

12420 Milestone Center Drive

Germantown, MD 20876

Shallow Intermediate Deep

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

PFBS Results (μg/Kg)

ND

>ND - 10

>10 - 1,900

>1,900 - 25,000

>25,000

0 200 400 800

Feet

AECOM 6-1
AOI01-01

AOI01-02

AOI01-03 AOI01-04

AOI01-05

AOI01-06

AOI01-07

AOI01-08

AOI01-09

AOI01-10

Legend

Facility Boundary

Storm Water Utility Line

AOI01-01

AOI01-02

AOI01-03 AOI01-04

AOI01-05

AOI01-06

AOI01-07

AOI01-08

AOI01-09

AOI01-10

AOI01-01

AOI01-02

AOI01-03 AOI01-04

AOI01-05

AOI01-06

AOI01-07

AOI01-08

AOI01-09

AOI01-10

­ Figure 6-4

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection for PFAS at Windsor Locks AASF, CT

6/24/2021

6/24/2021

6/24/2021

MS

AM

CM

GIS BY

CHK BY

PM

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

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

6/24/2021

1:4,859

C:\Users\stankevichm\OneDrive - AECOM Directory\ARNG_PFAS_GIS_60552172\MXDs\CT\Windsor_Locks_AASF_Figures\Windsor_Locks_SI_Figures\SI_Report\Results\Fig_6-4_Windsor_Locks_AASF_SI_GW_Results.mxd

Site Inspection Groundwater Results

12420 Milestone Center Drive

Germantown, MD 20876

PFOA PFOS PFBS

PFOA Results (ng/L)

ND

>ND - 10

>10 - 40

>40 - 70

>70 - 400

>400

0 200 400 800

Feet

PFOS Results (ng/L)

ND

>ND - 10

>10 - 40

>40 - 70

>70 - 400

>400

PFBS Results (ng/L)

ND

>ND - 100

>100 - 600

>600 - 1,000

>1,000 - 6,000

>6,000

AECOM 6-1
Site Inspection Report

Army Aviation Support Facility, Windsor Locks, Connecticut

AECOM 7-1

7. Exposure Pathways

The CSM for AOI 1, revised based on the SI findings, is presented on Figure 7-1. The 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 figure uses 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 

PFOA, PFOS, or PFBS 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 PFOA, PFOS, 

or PFBS above the SLs. Areas with an identified potentially complete pathway may warrant further 

investigation. 

In general, the potential routes of exposure to PFAS are ingestion and inhalation. Human 

exposure via the dermal contact pathway may occur, and current risk practice suggests it is an 

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

sparse and continue to be the subject of PFAS toxicological study. The receptors evaluated are 

consistent with those listed in USEPA guidance for risk screening (USEPA, 2001). Receptors at 

the facility include site workers (e.g., facility staff and visiting soldiers), construction workers, 

trespassers, residents outside the facility boundary, and recreational users outside of the facility 

boundary. 

7.1 Soil Exposure Pathway

The SI results for PFOA, PFOS, and PFBS in soil were used to determine whether a potentially 

complete pathway exists between the source and potential receptors at AOI 1 based on the 

aforementioned criteria. 

7.1.1 AOI 1

Between 2003 and 2015, AFFF may have been released at AOI 1 during fire training activities. 

AFFF was used to extinguish controlled burns at the Wash Rack during fire training. Additionally,

mobile fire extinguishers containing AFFF were discharged to the floor drains in Building 152. 

PFOA, PFOS, and PFBS were detected in soil at AOI 1 and confirm the release of PFAS to soil. 

Based on the results of the SI, ground-disturbing activities could potentially result in site worker, 

construction worker, or trespasser exposure to PFOA, PFOS, and PFBS via inhalation of dust. 

Additionally, off-facility residents and recreational users may potentially be exposed to PFOA, 

PFOS, and PFBS via inhalation of dust caused by on-facility ground disturbing activities. Grounddisturbing activities could also potentially result in site worker, construction worker, or trespasser 

exposure via ingestion of surface soil. Lasty, ground-disturbing activities could also potentially 

result in construction worker exposure to PFOA, PFOS, and PFBS in subsurface soil via ingestion. 
Site Inspection Report

Army Aviation Support Facility, Windsor Locks, Connecticut

AECOM 7-2

Construction activities were observed to be occurring near the facility’s access control point at the 

time of the SI field work. The CSM is presented on Figure 7-1. 

7.2 Groundwater Exposure Pathway

The SI results for PFOA, PFOS, and PFBS in groundwater were used to determine whether a 

potentially complete pathway exists between the source and potential receptors at AOI 1 based 

on the aforementioned criteria.

7.2.1 AOI 1

PFOA and PFOS in groundwater exceeded the individual SLs of 40 ng/L at both potential PFAS 

release areas, Wash Rack (AOI01-02) and Building 152 (AOI01-04); at AOI01-01, located in the 

southern portion of the facility upgradient of the identified potential release areas; and at AOI01-

03, located east of the drainage swale along the edge of the facility parking lot. Additionally, PFOA 

in groundwater exceeded the SL at AOI01-05, on the north side of Building 200, and PFOS in 

groundwater exceeded the SL at upgradient locations AOI01-07, AOI01-08, and AOI01-09 along 

the western and southern facility boundaries.

It is unknown whether offsite potable wells are located downgradient of AOI 1; therefore, the 

ingestion exposure pathway for off-facility residents and off-facility recreational users is 

considered potentially complete. Windsor Locks AASF receives its potable water from the 

Connecticut Water Company. Therefore, the ingestion exposure pathway for site workers and 

trespassers is considered incomplete. Depths to water measured in April 2021 during the SI 

ranged from 3.37 to 8.11 feet bgs. Therefore, groundwater may be encountered during 

construction activities and the ingestion exposure pathway for construction workers is considered 

potentially complete. Construction activities were observed to be occurring near the facility’s 

access control point at the time of the SI field work. The CSM is presented on Figure 7-1. 

7.3 Surface Water and Sediment Exposure Pathway

Surface water and sediment samples were not collected as part of the SI at AOI 1; therefore, the 

SI results for PFOA, PFOS, and PFBS in soil and groundwater, in combination with knowledge of 

the fate and transport properties of PFAS, were used to determine whether a potentially complete 

pathway exists between the source and potential receptors.

7.3.1 AOI 1

PFAS are water soluble and can migrate readily from soil to surface water via leaching and runoff. Because PFOA, PFOS, and PFBS were detected in soil and groundwater at AOI 1, it is 

possible that those compounds may have migrated from soil and groundwater to the wetlands in 

the northeast of the facility via groundwater discharge, surface water runoff, or the stormwater 

detention system that outfalls to the drainage swales on the eastern and western portions of the 

property. Therefore, the surface water and sediment ingestion exposure pathway for site workers, 

construction workers, or trespassers is considered potentially complete. 

Windsor Locks AASF is drained to drainage swales on the eastern and western portions of the 

property that are routed via a culvert to Spencer Brook, an intermittent stream that discharges to 

Stoney Brook. Stoney Brook subsequently discharges into the Connecticut River further 

downstream. Due to potential recreational use of Spencer Brook, the surface water and sediment 

ingestion exposure pathway for off-facility residents and recreational users is also considered 

potentially complete.
Media

SOURCE PATHWAY RE

AOI1

Mobile Fire 

Extinguisher 

Discharge

PFAS in 

Surface Soil

PFAS in 

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

IngestionIngestion

Ingestion

Ingestion

Hum

C

Flow-Chart ContinuesPartial / Possible FlowFlow-Chart StopsIncomplete PathwayPotentially Complete PathwayPotentially Complete Pathway with Exceedance of SL

/ / 

LEGEND

/ / / 

Figure 

Conceptual Site 

Windsor Loc

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

PFAS in 

Surface 

Water

Surface 

Water Flow

NOTES1. The resident and recreational usersrefer to off-site receptors.2. Inhalation of dust for off-site receptorsis likely insignificant.

3. Human consumption of fish

potentially affected by PFAS is possible.4. Active construction within AOI 1 was occurring as of the date of SI field work.. 

Site 

Worker

Cons

Wo

Site 

Worker

Cons

Wo
Site Inspection Report

Army Aviation Support Facility, Windsor Locks, Connecticut

AECOM 7-4

THIS PAGE INTENTIONALLY BLANK
Site Inspection Report

Army Aviation Support Facility, Windsor Locks, Connecticut

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 26 to 29 April 2021 and consisted of utility clearance, 

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

groundwater sample collection, and land surveying. Field activities were conducted in accordance 

with the SI QAPP Addendum (AECOM, 2021a), except as previously noted in Section 5.8.

To fulfill the project DQOs set forth in the approved SI QAPP Addendum (AECOM, 2021a), 

samples were collected and analyzed for a subset of PFAS by LC/MS/MS compliant with QSM

5.3 Table B-15 as follows. The 18 PFAS analyzed as part of the ARNG SI program are specified 

in Section 5.7 of this Report.

• 26 soil samples from 10 boring locations;

• 10 grab groundwater samples from 10 temporary well locations; and

• 18 QA samples.

The information gathered during this investigation was used to determine if PFOA, PFOS, and/or

PFBS were present at or above SLs. Additionally, the CSMs were refined to assess whether a 

potentially complete pathway exists between the source and potential receptors for potential 

exposure to PFOA, PFOS, and PFBS at the AOIs, which are described in Section 7.

8.2 SI Goals Evaluation

As described in Section 4.2, the SI activities were designed to achieve six main goals or DQOs. 

This section describes the SI goals and the conclusions that can be made for each based on the 

data collected during this investigation. 

1. Determine the presence or absence of PFOA, PFOS, and PFBS at or above SLs.

PFOA, PFOS, and PFBS were detected at the facility in soil and groundwater. PFOA, 

PFOS, and PFBS were detected both at the source areas, as well as at the upgradient 

facility boundary and the downgradient facility boundary, between the potential PFAS 

release areas and potential drinking water receptors. PFOA and PFOS in groundwater 

exceeded the individual SLs of 40 ng/L at both potential PFAS release areas, Wash Rack 

(AOI01-02) and Building 152 (AOI01-04); at AOI01-01, located in the southern portion of 

the facility upgradient of the identified potential release areas; and at AOI01-03, located 

east of the drainage swale along the edge of the facility parking lot. Additionally, PFOA in 

groundwater exceeded the SL at AOI01-05, on the north side of Building 200, and PFOS 

in groundwater exceeded the SL at upgradient locations AOI01-07, AOI01-08, and AOI01-

09 along the western and southern facility boundaries. PFOA, PFOS, and PFBS were 

detected in soil at AOI 1, indicating there was likely a release of PFAS-containing 

materials; however, the detected concentrations were several orders of magnitude lower 

than the soil SLs.

2. Develop information to potentially eliminate a release from further consideration because 

it is determined that it poses no significant threat to human health or the environment.
Site Inspection Report

Army Aviation Support Facility, Windsor Locks, Connecticut

AECOM 8-2

No potential PFAS release areas were removed from further consideration based on the 

groundwater and soil data collected during the SI. PFOA and PFOS were detected in 

groundwater above the SLs at both of the potential PFAS release areas (Wash Rack and 

Building 152); therefore, they may pose a threat to human health or the environment.

3. Determine the potential need for a TCRA (applies to drinking water only). The primary 

actions that will be considered include provision of alternative water supplies or wellhead 

treatment.

Based on the data collected during this SI, there is a potentially complete pathway 

between the detections of PFOA and PFOS above SLs at Windsor Locks AASF and 

potential downgradient offsite drinking water receptors. Windsor Locks AASF receives its 

potable water from the Connecticut Water Company, but it is unknown whether private 

potable wells exist downgradient of the facility. Using online resources, wells were 

researched to a 4-mile radius of the facility; however, the state of Connecticut does not 

have an online well database. Agricultural areas exist to the north-northwest of the facility 

and it is possible that unlisted groundwater wells may exist in this area. Therefore, the 

drinking water pathway is considered potentially complete.

4. Collect data to better characterize the release areas for more effective and rapid initiation 

of a RI (if determined necessary).

The geological data collected as part of the SI indicate a highly permeable and conductive 

environment, with soils dominated by sand (ranging from well to poorly graded) with thin 

interbedded lenses of gravel, silt, and clay. These observations are consistent with the 

glaciofluvial deposits of the surrounding area. Given the shallow depth of the borings, it is 

difficult to determine how the surficial geology impacts the nature and extent of PFAS. 

However, the borings confirmed an unconfined shallow aquifer exists approximately 3.37 

to 8.11 feet bgs. Groundwater flow direction at the facility is generally towards the drainage 

swale on the eastern portion of the facility. West of the eastern drainage swale, 

groundwater flow is generally to the northeast across the facility towards the drainage 

swale, while east of the drainage swale, groundwater flow is to the west-southwest back 

toward the drainage swale. Groundwater is potentially in communication with the drainage 

swale, which ultimately discharges to Spencer Brook. The limited amount of fine-grained 

material (silt and clay) observed in the shallow borings indicates the shallow aquifer is 

likely transmissive. These geologic and hydrogeologic observations will inform the 

development of the technical approach for the RI.

5. If PFOA, PFOS, and PFBS are determined to be present, aim to evaluate whether the 

concentrations can be attributed to on-facility or off-facility sources that were identified 

within 4 miles of the installation as part of the PA (e.g., fire stations, major manufacturers, 

other DoD facilities)

Based upon the evaluation of groundwater and soil results in comparison to SLs, in 

combination with the groundwater flow direction analysis, the results of the SI indicate that 

the sources of detected concentrations of PFOA, PFOS, and PFBS at AOI 1 (the Wash 

Rack and Building 152) are possibly attributable to ARNG activities. However, based on 

the exceedances of PFOA and PFOS in groundwater along the upgradient facility 

boundary (both east and west), it is possible that potential releases from off-facility, 

adjacent sources are migrating onto the facility. Known potential offsite, adjacent sources 

at the Bradley International Airport were identified in the PA Report (AECOM, 2020) and 

SI QAPP Addendum (AECOM, 2021a) and are shown on Figure 3-1.

6. Determine whether a potentially complete pathway exists between the source and 

potential receptors and whether ARNG is the likely source of the contamination. 
Site Inspection Report

Army Aviation Support Facility, Windsor Locks, Connecticut

AECOM 8-3

Detections of PFOA, PFOS, and PFBS in soil at the Wash Rack and Building 152 release 

areas and at the upgradient and downgradient facility boundaries indicate there is a 

potentially complete exposure pathway between the source and site workers, construction 

workers, trespassers, and off-facility recreational users and residents. The SL 

exceedances of PFOA and PFOS in surficial groundwater indicate there is a potentially 

complete exposure pathway between the source and construction workers, trespassers, 

and off-facility recreational users and residents. It is not known at this time whether 

releases on ARNG property are likely the primary source of the contamination in 

groundwater.

8.3 Outcome 

Based on the CSMs developed and revised in light of the SI findings, there is potential for 

exposure to drinking water receptors from AOI 1 from sources on the facility resulting from 

historical DoD activities. Sample analytical concentrations collected during the SI were compared 

against the project SLs for PFOA, PFOS, and PFBS in soil and groundwater, as described in 

Table 6-1. The following bullets summarize the SI results:

• PFOA and PFOS in groundwater at AOI 1 exceeded the individual SLs of 40 ng/L at both 

potential PFAS release areas, Wash Rack (AOI01-02) and Building 152 (AOI01-04), and in 

groundwater at upgradient and downgradient locations at the facility. The maximum 

concentrations of PFOA and PFOS were 298 ng/L (at location AOI01-03) and 581 ng/L (at 

location AOI01-08), respectively. Based on the results of the SI, further evaluation of AOI 1 

is warranted in the RI.

• PFOA, PFOS, and PFBS were detected in soil at AOI 1, indicating a release of PFAScontaining materials occurred; however, the detected concentrations were several orders of 

magnitude lower than the soil SLs.

Table 8-1 summarizes the SI results for soil and groundwater. Based on the CSMs developed 

and revised in light of the SI findings, there is potential for exposure to drinking water receptors 

caused by DoD activities at the facility.

Table 8-2 summarizes the rationale used to determine if an AOI should be considered for further 

investigation under CERCLA and undergo an RI. Based on the results of this SI, further evaluation 

is warranted in the RI for AOI 1.

Table 8-1: Summary of Site Inspection Findings

AOI Potential PFAS 

Release Area

Soil –

Source Area

Groundwater –

Source Area

Groundwater –

Facility 

Boundary

1 Wash Rack

1 Building 152

Legend:

N/A = Not applicable 

= detected; exceedance of the screening levels

= detected; no exceedance of the screening levels

= not detected
Site Inspection Report

Army Aviation Support Facility, Windsor Locks, Connecticut

AECOM 8-4

Table 8-2: Site Inspection Recommendations

AOI Description Rationale Future Action

1 Wash Rack, Building 

152

Exceedances of SLs in groundwater at 

source areas. No exceedances of SLs in 

soil. 

Proceed to RI 
Site Inspection Report

Army Aviation Support Facility, Windsor Locks, Connecticut

AECOM 9-1

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