FINAL

Site Inspection Report

Army Aviation Support Facility #1

and Armory

West Bend, Wisconsin

Perfluorooctanesulfonic Acid (PFOS) and 

Perfluorooctanoic Acid (PFOA) Impacted Sites

ARNG Installations, Nationwide

March 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....................................................................................................2-3

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

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

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

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

2.4 Other PFAS Investigations ....................................................................................2-4

2.5 Potable Water Sampling........................................................................................2-4

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

3.1 AOI 1 Fire Suppression System Testing ................................................................3-1

3.2 AOI 2 Tri-MaxTM Release.......................................................................................3-1

3.3 Adjacent Sources ..................................................................................................3-1

3.3.1 West Bend Municipal Airport .......................................................................3-1

3.3.2 Americraft CookWare Manufacturing...........................................................3-1

3.3.3 West Bend Waste Water Treatment Plant ...................................................3-1

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

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

4.2 Goals of the Study.................................................................................................4-1

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

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 Water Level Measurements...................................................................................5-4

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

5.7 Laboratory Analytical Methods ..............................................................................5-4

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

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

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

6.2 Soil Physicochemical Analyses .............................................................................6-1

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

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

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

6.3.3 AOI 1 Conclusions ......................................................................................6-2

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

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

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

6.4.3 AOI 2 Conclusions ......................................................................................6-3

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

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

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

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

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

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

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

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. Field Change Request Forms

 B4. Survey Data

Appendix C Photographic Log

Appendix D TPP Meeting Minutes

Appendix E Boring Logs 

Appendix F Analytical Results

Appendix G Laboratory Reports

Figures

Figure 2-1 Facility Location

Figure 2-2 Facility Topography

Figure 2-3 Groundwater Features

Figure 2-4 Groundwater Contours

Figure 2-5 Surface Water Features

Figure 2-6 Potable Well Sampling Area 

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 PFOA and PFOS Detections in Groundwater

Figure 7-1 Conceptual Site Model, AOI 1 Fire Suppression System Testing and AOI 2 TriMaxTM Release 

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 Sample Locations

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

Table 5-3 Groundwater Elevations at Temporary Groundwater Monitoring Wells

Table 6-1 Screening Levels (Soil and Groundwater)

Table 6-2 PFAS Detections in Surface Soil

Table 6-3 PFAS Detections in 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 sulfonate

8:2 FTS 8:2 Fluorotelomer sulfonate

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

bgs below ground surface 

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act 

CoC chain of custody

CSM conceptual site model

DA Department of the Army

DO dissolved oxygen

DoD Department of Defense

DPT direct-push technology

DQI data quality indicator

DQO data quality objective

DUA data usability assessment

DVR data validation report 

EIS extraction internal standards

ELAP Environmental Laboratory Accreditation Program

FedEx Federal Express

ERB equipment rinsate blank

FRB Field Reagent Blank

gpm gallons per minute

HDPE high-density polyethylene 

IDW investigation-derived waste

IIS Injection internal standards

ISC Instrument sensitivity check

ITRC Interstate Technology Regulatory Council

LC/MS/MS liquid chromatography with tandem mass spectrometry

LCS laboratory control spike

LCSD laboratory control spike duplicate

LOQ limit of quantitation

MDL method detection limit

MS matrix spike

MSD matrix spike duplicate

NELAP National Environmental Laboratory Accreditation Program

NEtFOSAA N-ethyl perfluorooctanesulfonamidoacetic acid
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ng/L nanograms per liter

NMeFOSAA N-methyl perfluorooctanesulfonamidoacetic acid

ORP oxidation-reduction potential

OSD Office of the Secretary of Defense

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

PPE personal protective equipment

PQAPP Programmatic UFP-QAPP

PVC poly-vinyl 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

TOC total organic carbon

TPP Technical Project Planning

UCMR 3 Third Unregulated Contaminant Monitoring Rule

UFP Uniform Federal Policy

US United States

USACE United States Army Corps of Engineers

USCS Unified Soil Classification System

USEPA United States Environmental Protection Agency

USFWS United States Fish and Wildlife Service

WIARNG Wisconsin Army National Guard

WIDNR Wisconsin Department of Natural Resources
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WWTP Waste Water Treatment Plant
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AECOM ES-1

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 

West Bend Army Aviation Support Facility (AASF) #1 and Armory (also referred to as the “facility”), 

Wisconsin. 

West Bend AASF #1 and Armory is in Washington County, Wisconsin, approximately 2 miles east 

of West Bend, 30 miles northwest of Milwaukee, and 75 miles northeast of Madison. The facility 

is accessible from East Washington Street by Chopper Drive and Trenton Road.

West Bend AASF #1 and Armory was constructed in 2004 on a parcel of land, approximately 35-

acres, owned by the City of West Bend, and leased to the Wisconsin ARNG (WIARNG); the 

current lease agreement expires September 2075. The current West Bend AASF #1 and Armory

facilities include administrative offices, classrooms, and hangars for the operation, maintenance, 

and repair of WIARNG rotary-winged aircraft. Two potential PFAS release areas were identified 

in the PA Report (AECOM Technical Services, Inc. [AECOM], 2019). The release areas, which 

include the fire suppression testing area and the Tri-MaxTM training area, were grouped into two

AOIs and investigated during the SI. The SI field activities were conducted from 26 to 29 October

2020 and included the collection of soil and groundwater samples.

To fulfill the project Data Quality Objectives set forth in the approved SI Quality Assurance Project 

Plan Addendum (AECOM, 2020b), samples were collected and analyzed for a subset of 18 PFAS 

by liquid chromatography with tandem mass spectrometry compliant with Quality Systems Manual 

5.1 Table B-15. The 18 PFAS analyzed as part of the ARNG SI program are specified in Section 

5.8 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 dated 15 October 2019 (Assistant Secretary of Defense, 2019). The ARNG 

PFAS SIs follow this DoD policy and, should the maximum site concentration for sampled media 

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

CERCLA. The SLs apply to three compounds, PFOA, PFOS, and PFBS, for both soil and 

groundwater, as presented in Table ES-1. All other results presented in this report are considered 

informational in nature and serve as an indication as to whether soil, groundwater, sediment, and 

surface water 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 in groundwater at AOI 1: Fire Suppression System Testing exceeded the SL of 40

nanograms per liter (ng/L), with a concentration of 990 ng/L at the source area, AOI01-01. 

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

• PFOS in groundwater at AOI 2: Tri-MaxTM Release exceeded the SL of 40 ng/L in four of 

the well locations, with concentrations ranging from 225 ng/L to 702 J- ng/L. Based on the 

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

• The detected concentrations of PFOA, PFOS, and PFBS in soil samples from all AOIs were 

below the SLs. 
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West Bend AASF #1 and Armory, West Bend, Wisconsin

AECOM ES-2

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

models developed and revised in light of the SI findings, there is potential for exposure to offfacility residential drinking water receptors caused by DoD activities at or adjacent to the facility. 

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: Fire Suppression System Testing, and AOI 2: Tri-MaxTM Release.

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

PFOA 130 1,600 40

PFOS 130 1,600 40

PFBS 130,000 1,600,000 40,000

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 Regional Screening Level

Calculator. Hazard Quotient (HQ) = 0.1. 15 October 2019.

b.) If only one PFAS is present, a HQ of 1 applies and the values presented would increase by a factor of x10.

c.) bgs= below ground surface, μg/kg= micrograms per kilogram

Table ES-2: Summary of Site Inspection Findings

AOI Potential PFAS 

Release Area

Soil –

Source Area

Groundwater –

Source Area

Groundwater –

Facility 

Boundary

1 Fire Suppression System Testing

2 Tri-MaxTM Release

Legend:

= 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 Fire Suppression 

System Testing

Exceedances of SLs in groundwater at 

source area. No exceedances of SLs in 

soil. 

Proceed to RI 

2 Tri-MaxTM Release

Exceedances of SLs in groundwater at 

source area. 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 West Bend 

Army Aviation Support Facility (AASF) #1 and Armory (also referred to as the “facility”), Wisconsin.

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 poly-fluoroalkyl 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 the West Bend AASF #1 and Armory (AECOM, 2019) that identified two

potential PFAS release areas, which were grouped into twoAreas of Interest (AOIs). 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

West Bend AASF #1 and Armory is in Washington County, Wisconsin, approximately 2 miles east 

of West Bend, 30 miles northwest of Milwaukee, and 75 miles northeast of Madison (Figure 2-1). 

The facility is accessible from East Washington Street by Chopper Drive and Trenton Road.

West Bend AASF #1 was constructed in 2004 on a parcel of land, approximately 35-acres, owned 

by the City of West Bend, and leased to the WIARNG; the current lease agreement expires 

September 2075. The current West Bend AASF #1 and Armory facilities include administrative 

offices, classrooms, and hangars for the operation, maintenance, and repair of WIARNG rotarywinged aircraft. 

2.2 Facility Environmental Setting

West Bend AASF #1 and Armory lies within the Milwaukee River Basin, which encompasses 

several land tributaries to the Milwaukee River. The topography of the area is comprised of rolling 

hills and numerous drumlins (Figure 2-2). The elevation of the facility is approximately 896 feet 

above mean sea level. The surrounding area is covered by cropland, grasslands, wooded area, 

and wetlands (Wisconsin Department of Natural Resources [WIDNR, 2001]).

The following sections include information on geology, hydrogeology, hydrology, climate, current 

and future land use, and critical habitat. The facility geology and groundwater features are 

presented on Figure 2-3, groundwater elevations and contours are presented on Figure 2-4, and 

surface water features are presented on Figure 2-5.

2.2.1 Geology

West Bend AASF #1 and Armory is situated in the Southeast Glacial Plains, which are 

characterized by having a rolling topography with silt loam soils, an outstanding array of glacial 

landforms, and numerous wetlands (WIDNR, 2015). The surficial geology is strongly influenced 

by the Pleistocene glacial advance, which modified the land surface by carving and gouging out 

soft bedrock and depositing hills and ridges of sand and gravel, as well as flat lake beds of sand, 

silt, and clay (Wisconsin Geological and Natural History Survey, 2005). The thickness of these 

deposits typically ranges up to 100 feet but can exceed 500 feet in the bedrock valleys (Young 

and Batten, 1980).

The facility is underlain by Quaternary-aged sediments. Towards the Milwaukee River, on the 

southern portion of the facility, the surficial geology is composed of postglacial sand and silt. The 

rest of the facility is directly underlain by the silt and sand facies of the Waubeka Member of the 

Holy Hill Formation. This member is composed primarily of well-sorted silt with some sand and

clay (Mickelson and Syverson, 1997). Underlying the Waubeka Member is the New Berlin 

Member of the Holy Hill Formation. At the facility, this member is characterized as diamicton, 

gravel, and sand (Mickelson and Syverson, 1997).

Beneath the Quaternary-aged sediments, West Bend AASF #1 and Armory partially overlies a

bedrock valley. Directly to the east of the facility, the uppermost bedrock is undifferentiated 

Silurian-aged dolomite, while bedrock directly beneath the facility is primarily Ordovician-aged 

shale of the Maquoketa Formation (Figure 2-3; Evans et al., 2004a). The precise extent of the 

Silurian dolomite near the facility is uncertain; it may be partially present beneath glacial deposits 

at the eastern portion of the facility, near the West Bend Municipal Airport (Evans et al., 2004a). 

The dolomite is often undifferentiated; however, the uppermost dolomite is known to be of the 
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Manistique Formation, which is composed of gray, fine- to medium-grained dolomite with thin to 

medium bed thickness (Evans et al., 2004a). Depth to bedrock at the facility ranges between 200 

and 400 feet below ground surface (bgs) (Evans et al., 2004b). Regionally, thickness of the 

undifferentiated dolomite ranges from 0 to 700 feet, depending on the degree of post-depositional 

erosion. Near the facility, the estimated dolomite thickness is believed to be the same as the 

saturated thickness of the Eastern Dolomite aquifer, which is between 100 to 200 feet. Directly 

underlying the dolomite is the Ordovician-aged Maquoketa Shale of the Maquoketa Formation 

(Figure 2-3; Young and Batten, 1980). All bedrock units dip regionally eastward toward Lake 

Michigan (Young and Batten, 1980).

2.2.2 Hydrogeology

The facility is directly underlain by a surficial aquifer that resides within the unconsolidated sand 

and gravel deposits of glacial outwash, glacial-lake deposits, or alluvium. Wells screened in this 

aquifer have historically been used for domestic purposes and have a wide range of yields; 

however, wells at West Bend have reached high yields of 500 to 1,750 gallons per minute (gpm) 

(Young and Batten, 1980).

Directly east of the facility, the surficial aquifer is underlain by the Eastern Dolomite aquifer (also 

known as the Silurian or Niagaran aquifer). This aquifer resides within the undifferentiated 

Silurian-aged dolomites and produces water from interconnected cracks, pores, and dissolution 

channels. The Eastern Dolomite aquifer is thickest along the east side of Wisconsin and thins to 

the west (Wisconsin Geological and Natural History Survey, 2019). Historically, the Eastern 

Dolomite aquifer has been sourced for domestic, public, industrial, and agricultural purposes, with 

yields typically ranging between 150 and 500 gpm (Young and Batten, 1980). The Eastern 

Dolomite aquifer is unconfined near the facility and is particularly vulnerable to contamination 

where the unconsolidated deposits are relatively thin. Vertical cracks and cavities may also result 

in the quick vertical migration of groundwater (Wisconsin Geological and Natural History Survey, 

2019).

The facility is primarily underlain by the Maquoketa Shale, which separates the Eastern Dolomite

aquifer from the Cambrian-Ordovician aquifer. The shale restricts the vertical migration of 

groundwater and therefore acts as a regional aquiclude (Young and Batten, 1980). The CambrianOrdovician aquifer resides in the Ordovician- and Cambrian-aged sandstone and dolomite units 

below the Maquoketa Shale, yielding water from fractures and pore spaces between the sand 

grains or from cracks and fractures (Wisconsin Geological and Natural History Survey, 2019). 

Depth to groundwater in the area ranges from 5 to 25 feet bgs. Shallow groundwater on the east 

and west side of the facility likely flows either towards the Milwaukee River or to Wingate Creek, 

which discharges into the Milwaukee River just south of the facility (Figure 2-4). Groundwater in 

the regional bedrock aquifers is expected to flow generally east towards Lake Michigan. Aquifer 

recharge is predominantly through infiltration of precipitation, although some recharge occurs 

from open water sources (Stantec Consulting Services, Inc., 2018).

No known municipal drinking water supply wells are located within the boundary of the West Bend 

AASF #1 and Armory; however, public supply, domestic, and unknown well types exist within 4 

miles of the facility (Figure 2-3). Domestic and unknown wells are downgradient of West Bend 

AASF #1; and other unknown wells are locally up-, down-, and cross-gradient and therefore, may 

be impacted by potential PFAS releases. Several public drinking water wells are located side 

gradient and regionally upgradient of the facility but are unlikely to be impacted by potential PFAS 

releases (Figure 2-3). Drinking water for West Bend AASF #1 and Armory is supplied by the City 

of West Bend, which uses the Lake Michigan and the bedrock aquifers as its drinking water 

sources (WIDNR, 2001).
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The Third Unregulated Contaminant Monitoring Rule (UCMR 3) sampling program was an 

addition to the 1996 Safe Drinking Water Act which requires USEPA to, every 5 years, issue a 

new list of no more than 30 unregulated contaminants to be monitored by public water systems. 

Six PFAS compounds are currently included as part of the UCMR 3 list. The UCMR 3 dataset was 

evaluated to determine which public water systems were sampled for PFAS within a 20-mile 

radius of a site. The City of West Bend public drinking water was sampled; results for the six PFAS 

compounds sampled were below the USEPA Health Advisory. No other public water system was 

sampled within 20 miles of the facility. Observed groundwater elevations from the October 2020

synoptic gauging event and corresponding contours are displayed on Figure 2-4.

2.2.3 Hydrology

West Bend AASF #1 and Armory is within the Milwaukee River Basin, which includes six 

watersheds. The facility is located between the Silver Creek-Milwaukee River Watershed and the 

Village of Newburg-Milwaukee Watershed (Figure 2-5). The tributary that runs between West 

Bend AASF #1 and the Armory is Wingate Creek, which discharges to the Milwaukee River. The 

WIARNG Armory is located on the east side of West Bend AASF #1. The facility is currently 

connected to the City of West Bend sanitary sewer system. On the west side of the facility, the 

surface water flows to the south and east towards the stormwater basin. On the east side of the 

facility, surface water flows northwest and southwest to Wingate Creek, then to the Milwaukee 

River.

2.2.4 Climate

The climate of West Bend consists of warm summers, and winters with freezing, dry, and windy 

months. Seasonally, temperatures vary from summer highs of 81.5 degrees Fahrenheit (°F) to 

winter lows of 9.1°F; the average temperature is 55.0°F. Average precipitation is 31.2 inches of 

rain, and the average snowfall is 43.3 inches (World Climate, 2021). The area is subject to severe 

storms in the winter.

2.2.5 Current and Future Land Use

West Bend AASF #1 and Armory is a controlled access facility with public roads and is adjacent 

to the West Bend Municipal Airport. The facility consists of a storage hangar, repair hangar, shops, 

and a two-story office area. Exterior features are vehicle parking areas, roads, aircraft parking, 

taxiways, and a 90-feet clear-span bridge. The West Bend Municipal Airport is owned and 

operated by the City of West Bend and provides private, commercial, corporate, cargo, and 

military air service. Future infrastructure improvements, land acquisitions, and land use controls 

are not anticipated to change. Reasonably anticipated future land use is not expected to change 

from the current land use described above.

2.2.6 Critical 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 Washington County, Wisconsin (US Fish and 

Wildlife Service [USFWS], 2018).

• Birds: Whooping crane, Grus americana (experimental population)

• Plants: Eastern prairie fringed orchid, Platanthera leucophaea (threatened)

• Mammals: Northern Long-Eared Bat, Myotis septentrionalis (threatened)

• Insects: Rusty patched bumble bee, Bombus affinis (endangered)
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2.3 History of PFAS Use

The primary source of PFAS at the facility is related to hangar fire suppression system testing and 

a single fire training exercise. The main hangar is equipped with a fire suppression system that is 

supplied by two 500-gallon tanks filled with 3 percent (%) aqueous film forming foam (AFFF). Bulk 

55-gallon drums of AFFF that supply the fire suppression system are housed in a building

connected to the hangar. The fire suppression system has been tested annually, since 2004, by

occasionally dispensing 20-40 gallons of 3% AFFF used during testing onto the grassy area

behind the building. A stormwater drain that discharges to Wingate Creek, which then discharges

to the Milwaukee River, is located at the edge of the grassy area. In addition, there was a onetime reported training event with one TriMaxTM fire extinguisher that occurred in a grassy area on

the east side of the Armory. The exact date, amount, and concentration of AFFF used are

unknown. The overlying surface water flow from the release area is north, then west to Wingate

Creek, which ultimately discharges to the Milwaukee River. A description of each AOI is presented

in Section 3.

2.4 Other PFAS Investigations

This SI is the first PFAS investigation completed at the West Bend AASF #1 and Armory. 

2.5 Potable Water Sampling

Due to historical fire suppression testing and Tri-MaxTM fire training activities, the potential exists 

for exposure to offsite residential drinking water receptors south of the West Bend AASF #1 and 

Armory boundary. Prior to sampling, approval was obtained from the Deputy Assistant Secretary 

of the Army for Environment, Safety and Occupational Health (DASA ESOH). Potable water 

samples were collected from five potable wells located in closest proximity to the facility boundary 

(downgradient of AOI 1 and AOI 2) (Figure 2-6). Sample results are provided in Appendix F, and 

the laboratory report is provided in Appendix G. 

• PFOA, PFOS, and PFBS were reported non-detect at all potable well locations.
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Site Inspection for PFAS at West Bend AASF #1 and Armory, WI

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12420 Milestone Center Drive

Germantown, MD 20876

Facility Location

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

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

C:\Users\grace.canham\AECOM Directory\Stankevich, Michael - ARNG_PFAS_GIS_60552172\MXDs\WI\West_Bend_Figures\West_Bend_SI_Figures\SI_Report\Fig_2-1_West_Bend_FacilityLocation.mxd

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12420 Milestone Center Drive

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Facility Topography

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

increment P Corp., GEBCO, USGS, FAO, NPS, NRCAN,

C:\Users\grace.canham\AECOM Directory\Stankevich, Michael - ARNG_PFAS_GIS_60552172\MXDs\WI\West_Bend_Figures\West_Bend_SI_Figures\SI_Report\Fig_2-2_West_Bend_FacilityTopography.mxd

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West Bend AASF #1 and Armory

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Site Inspection for PFAS at West Bend, WI

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1:79,200 ­ Figure 2-3 PM CM 3/29/2021

12420 Milestone Center Drive

Germantown, MD 20876

Groundwater Features

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

Geographics, CNES/Airbus DS, USDA, USGS,

C:\Users\stankevichm\OneDrive - AECOM Directory\ARNG_PFAS_GIS_60552172\MXDs\WI\West_Bend_Figures\West_Bend_SI_Figures\SI_Report\Fig_2-3_West_Bend_GroundwaterFeatures.mxd

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Groundwater Contours

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

Geographics, CNES/Airbus DS, USDA, USGS,

C:\Users\samir.khadka\AECOM Directory\Stankevich, Michael - ARNG_PFAS_GIS_60552172\MXDs\WI\West_Bend_Figures\West_Bend_SI_Figures\SI_Report\Fig_2-4_West_Bend_Groundwater_Contours.mxd

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Surface Water Features

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

Geographics, CNES/Airbus DS, USDA, USGS,

C:\Users\samir.khadka\AECOM Directory\Stankevich, Michael - ARNG_PFAS_GIS_60552172\MXDs\WI\West_Bend_Figures\West_Bend_SI_Figures\SI_Report\Fig_2-5_West_Bend_SurfaceWater.mxd

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Figure 2-6

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AECOM 2-10
Site Inspection Report

West Bend AASF #1 and Armory, West Bend, Wisconsin

AECOM 3-1

3. Summary of Areas of Interest 

This section presents a summary of each potential PFAS release area by AOI. Based on the PA 

findings, two AOIs were identified at the West Bend AASF #1 and Armory. These AOIs include the 

fire suppression system testing releases at the main hangar and a one-time fire extinguisher 

training on the east side of the Armory (Figure 3-1).

3.1 AOI 1 Fire Suppression System Testing

AOI 1 is the Fire Suppression System Testing area, where 20-40 gallons of 3% AFFF were 

dispensed annually onto the grassy area behind the building, which took place annually from 

2004 to 2019. The main hangar fire suppression system is supplied by two 500-gallon tanks 

filled with 3% AFFF. The AFFF tanks, pumps, and four bulk 55-gallon drums of AFFF that supply 

the fire suppression system are housed in a building connected to the hangar. The stormwater 

drain within AOI 1 flows through the stormwater system to the south, where it discharges to a 

stormwater basin on the south side of the property. Additionally, if there is flooding at the 

stormwater basin, surface water can overflow to the Milwaukee River. In 2018, the AFFF 

dispensed during the annual fire suppression system testing was containerized and removed 

from the facility for offsite disposal. Since then, the annual inspections no longer include flow 

testing, and therefore no AFFF is discharged or disposed.

3.2 AOI 2 Tri-MaxTM Release

AOI 2 is the Tri-MaxTM Release area, where a one-time reported training event with one Tri-MaxTM

fire extinguisher occurred in a grassy area located on the east side of the Armory. The exact date, 

amount, and concentration of AFFF used are unknown. The surface water flows northwest and 

southwest toward Wingate Creek, and ultimately to the Milwaukee River.

3.3 Adjacent Sources 

Three potential off-facility sources of PFAS are adjacent to the AASF and are not under the control 

of the WIARNG. A description of each off-facility source is presented below and shown on Figure 

3-1.

3.3.1 West Bend Municipal Airport

The West Bend Municipal Airport was constructed in 1928 and is owned and operated by the City 

West Bend. The AASF is southwest and adjacent to the West Bend Municipal Airport. The City of 

West Bend Fire Department provides fire emergency services for the West Bend Municipal 

Airport. 

3.3.2 Americraft CookWare Manufacturing

The Americraft Cookware Manufacturing building was identified due to the potential production 

of non-stick cookware containing Teflon® and other non-stick materials. The Americraft Cookware 

Manufacturing building is upgradient of the AASF. 

3.3.3 West Bend Waste Water Treatment Plant 

The West Bend Waste Water Treatment Plant (WWTP) is approximately 0.5 mile west and 

upgradient of the AASF. It is unknown if waste water at the WWTP is tested or treated for PFAS. 

Due to the nature and lack of knowledge regarding the WWTP, this was identified as a potential 

adjacent source. 
Site Inspection Report

West Bend AASF #1 and Armory, West Bend, Wisconsin

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Site Inspection for PFAS at West Bend, WI

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1:11,400 ­ Figure 3-1 PM CM 3/29/2021

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Areas of Interest

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

Geographics, CNES/Airbus DS, USDA, USGS,

C:\Users\stankevichm\OneDrive - AECOM Directory\ARNG_PFAS_GIS_60552172\MXDs\WI\West_Bend_Figures\West_Bend_SI_Figures\SI_Report\Fig_3-1_West_Bend_AOI.mxd

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Flow Direction

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AECOM 3-3
Site Inspection Report

West Bend AASF #1 and Armory, West Bend, Wisconsin

AECOM 3-4

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Site Inspection Report

West Bend AASF #1 and Armory, West Bend, Wisconsin

AECOM 4-1

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 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 fire training areas, 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).

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.
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3. Determine the potential need for a removal action. 

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

of an RI.

5. Identify within 4 miles of the installation other potential PFAS sources (fire stations, major 

manufacturers, other DoD facilities) and receptors, including both groundwater and

surface water receptors, to determine whether the ARNG is the likely source of PFAS, or 

whether there is an off-facility source of PFAS responsible for installation detections of 

PFAS (USEPA, 2005).

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 West Bend AASF #1, Wisconsin (AECOM, 2019);

• 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, 2020b); 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, 

2020b). 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:

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? 
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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 4 to 16 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 installation-specific DQOs. 

Both sampling and analytical activities are considered to assess whether the collected data are 

of the right type, quality, and quantity to support the decision-making (DoD, 2018a; DoD, 2018b; 

USEPA, 2017). 

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 (DVR) (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, 

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 field 

samples displayed EIS percent recoveries outside of quality control (QC) limits for 6:2 

fluorotelomer sulfonate (6:2 FTS) and 8:2 fluorotelomer sulfonate (8:2 FTS). The field sample 

results associated with the positive bias were positive and were qualified “J+”. The field sample 

results associated with the negative biases were all positive and were qualified “J-“. The field 

samples AOI01-01-GW and AOI01-01-SB-0-2 were re-extracted outside holding time with similar 

results. The initial results were recommended for retention in the data set.

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

to analysis as a requirement of DoD Quality Systems Manual (QSM) 5.1 to measure relative 

responses of target analytes. Several QC samples displayed IIS recoveries greater than the QC 

limit of 50% for surrogate M2PFDA, M2PFHxA, M2PFOA, and M4PFOS in the extraction analysis. 

PFAS analytes are not quantitated based on IIS recoveries in non-drinking water matrices; 

therefore, no impact on data quality is anticipated. 
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Calibration verifications were performed routinely to ensure that instrument responses for all 

calibrated analytes were within established QC criteria. The continuing calibration verification 

associated with QC batch 697682 displayed a percent recovery greater than the upper QC limit 

of 130%, at 321%, for 6:2 FTS. The associated field sample result was positive and was qualified 

“J+”. The instrument sensitivity checks (ISC) associated with QC batch 696644 recovered above 

the QC limits for perfluorotridecanoic acid (PFTrDA) at 144% and 147%. PFTrDA was not a target 

analyte in the batch associated with these ISC anomalies; no data qualifying action was required,

and no impact on data quality is anticipated.

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 SI QAPP Addendum (AECOM, 2020b).

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

batches. MS/MSD samples were submitted to the laboratory for analysis at a rate of 5%. MS/MSD 

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

one exception. The field sample AOI02-01-GW displayed an MS/MSD RPD outside the QC limit 

of 30%, at 39%, for perfluorotetradecanoic acid (PFTeDA). The associated field sample result was 

previously qualified due to an MS/MSD anomaly, and no further data qualifying action was 

required.

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, 2020b).

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, with one exception. The LCS associated with the QC sample 

LCS2086432 displayed a percent recovery greater than the upper QC limit of 130%, at 133%, for 

N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA). Field sample results were not 

flagged based on QC sample LCS recoveries; no impact on data quality is anticipated. 

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. Field samples 

AOI02-SS05 and AOI02-01-GW displayed MS/MSD percent recoveries less than the lower QC 

limit for several target analytes. The field sample results associated with MS/MSD recoveries less 

than 10% were positive and were qualified “J-“. The positive field sample results associated with 

percent recoveries less than 70% but greater than 10% were qualified “J-“, while non-detects 

were qualified “UJ-“.
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4.6.3 Representativeness

Representativeness qualitatively expresses the degree to which data accurately reflect facility

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 QSM 5.1 Table B-15, including the specific preparation requirements (i.e. ENVICarb or equivalent used), mass calibration, spectra, all the ion transitions identified in Table B-15 

were monitored, standards that contained both branch and linear isomers when available were 

used, 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, except for the pH analyses. For 

the pH analysis the technical holding time is “immediate”. The field sample results associated with 

the holding time exceedance were qualified “J”. The laboratory used approved standard methods 

in accordance with the SI QAPP Addendum (AECOM, 2020b) for all analyses.

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

control. All associated instrument blanks and method blanks were non-detect for all target 

analytes, with a few exceptions. Method blanks, MB2105014, MB2105014RE, and MB2105004 

displayed concentrations greater than the detection limit for perfluoroheanoic acid (PFHxA), 

PFOA, and PFBA, respectively. The positive field sample results associated with the method blank 

detections that were less than five times the blanks concentrations were qualified “U”, while field 

sample results greater than five times the blank concentrations required no data qualifying action. 

The instrument blank performed in QC batch 696772 displayed a concentration for 6:2 FTS 

greater than the detection limit. The positive associated field sample results displayed 

concentrations greater than five times the detections displayed in the instrument blank; no data 

qualifying action was required. 

Equipment blanks and field blanks were also collected for groundwater and soil samples. The 

field and equipment blanks WB-ERB-02, WB-ERB-01, and WB-FRB-01 all displayed 

concentrations for 6:2 FTS and PFBA greater than the detection limit. The positive field sample 

results associated with the blank detections that were less than five times the blank 

concentrations were qualified “U”, while field sample results greater than five times the blank 

concentrations required no data qualifying action. Non-detect field sample results required no 

data qualifying action.

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, WB-DECON-20200921, was non-detect for all 

target analytes. Based on the sample results, the potable water source was deemed acceptable 

for use during the investigation for decontamination of drilling equipment and during well 

installation.

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.

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 
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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 5.1 Table B-15 at 100%

• PFAS in soil by LC/MS/MS compliant with QSM 5.1 Table B-15 at 100%

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

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

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 SI QAPP Addendum (AECOM, 20120b). 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 SI QAPP Addendum 

(AECOM, 2020b), 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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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, Final Preliminary Assessment Report, West Bend

Army Aviation Support Facility, Wisconsin, dated November 2019 (AECOM, 2019);

• 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,

Final Preliminary Assessment Report, West Bend Army Aviation Support Facility,

Wisconsin, dated October 2020 (AECOM, 2020b);

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

• Final Site Safety and Health Plan, Final Preliminary Assessment Report, West Bend Army

Aviation Support Facility, Wisconsin, dated October 2020 (AECOM, 2020a).

The SI field activities were conducted from 26 to 29 October 2020 and consisted of direct push 

boring and soil sample collection, temporary monitoring well installation, and grab groundwater 

sample collection. Field activities were conducted in accordance with the QAPP Addendum 

(AECOM, 2020b), except as noted in Section 5.7. 

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

LC/MS/MS compliant with QSM 5.1 Table B-15 to fulfill the project DQOs:

• Twenty-three (23) soil grab samples from nine (9) boring locations;

• Six (6) soil grab samples from six (6) surface locations;

• Nine (9) groundwater grab samples from nine (9) temporary well locations; and

• Eighteen (18) Quality Assurance (QA) samples collected.

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. A Field Change Request Form is provided in Appendix B3, and sampling forms 

are provided in Appendix B2. 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, 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 27 August 2020, prior to SI field activities. Meeting 

minutes are provided in Appendix D. TPP meetings 1 and 2 were conducted in general 

accordance with EM 200-1-2.

The stakeholders for this SI include the ARNG G9, Wisconsin Department of Military Affairs, 

USACE, WIDNR, 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, 2020b). 

A TPP Meeting 3 was held on 12 May 2021 after the field event to discuss the results of the SI.

Meeting minutes for TPP 3 are included in Appendix D of this report. Future TPP meetings will 

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

5.1.2 Utility Clearance

Utility clearance was conducted by GLS Utility, LLC., with input from the AECOM field team. 

AECOM’s drilling subcontractor, Cascade Technical Services, LLC, contacted “Call811” one-call 

utility clearance contractor to notify them of intrusive work. Additionally, the first 5 feet of each 

boring were advanced using hand augering methods 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 

PFAS-free prior to the start of field activities. A sample of the City of West Bend Municipal Water 

Supply was collected from a spigot at the AASF on 21 September 2020, prior to mobilization, and 

analyzed for PFAS by LC/MS/MS compliant with QSM 5.1 Table B-15. The results of the potable 

well 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, 2020b). 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, 2020b). 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 five feet of the boring to be compliant with utility clearance procedures.

Three discrete soil samples were collected from the vadose zone for chemical analysis from each 

soil boring, except where the depth to groundwater was shallow, only allowing two samples to be 

collected. This process occurred at several sample locations on the east side of the facility, near 

AOI02. These deviations from the work plan are described further in Section 5.7. One subsurface 

soil sample approximately 1 foot above the groundwater table, and one subsurface soil sample 

at the mid-point between the ground surface and the groundwater table, were collected at each 

boring using DPT. 

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

boring locations were selected based on the AOI information as agreed on through TPP and SI

QAPP Addendum review.
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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. 

Clay layers exceeding 3 feet in thickness were encountered in four of the nine boreholes. Depths 

to the top of clay layer ranged from 2 to 5.5 feet bgs. A grain size analysis collected at AOI01-03 

at a depth of 6 to 8 feet had 65.50% silt, 32.27% clay, 2.23% sand and gravel. These results

suggest that what was identified as a lean clay by field tests may actually be categorized as clayrich silt when a grain size analysis is performed. 

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 5.1 Table B-15), TOC 

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

Addendum (AECOM, 2020b). 

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, equipment rinsate blanks 

(ERBs) were collected at a rate of 5% and analyzed for the same parameters as the soil samples. 

A temperature blank was placed in each cooler to ensure that samples were preserved at or below 

4 degrees Celsius (°C) during shipment.

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

accordance with the SI QAPP Addendum (AECOM, 2020b) 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 and purged for a total of approximately three well 

volumes after installation before collection of groundwater samples. After the recharge period, 

groundwater samples were collected using a peristaltic pump with PFAS-free HDPE tubing. Water 

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

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

the field sampling form (Appendix B2) 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 were 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 
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standard CoC procedures to the laboratory and analyzed for PFAS by LC/MS/MS Compliant with 

QSM 5.1 Table B-15 in accordance with the SI QAPP Addendum (AECOM, 2020b).

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

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

same parameters as the accompanying samples. One field reagent blank (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 4°C during shipment.

Temporary wells were abandoned in accordance with the SI QAPP Addendum (AECOM, 2020b) 

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 Water Level Measurements

Groundwater level measurements were taken prior to sampling. Groundwater elevation 

measurements were collected from each of the installed temporary wells. A groundwater flow 

contour map is provided in Figure 2-4. Groundwater elevation data are provided in Table 5-3. 

5.5 Surveying

Each well casing was surveyed by Wisconsin-Licensed land surveyors following guidelines 

provided in the SOPs provided in the SI QAPP Addendum (AECOM, 2019b). Survey data from 

the newly installed temporary wells on the facility were collected on 29 October 2020 in the 

Universal Transverse Mercator Zone 16 North projection with World Geodetic System 84 datum.

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 investigation-derived waste (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, 2020b) and with the DA

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

Soil IDW (i.e., soil cuttings) and liquid IDW (purge and decontamination water) generated during 

the SI activities were containerized in two, 55-gallon drums for soil IDW and one, 55-gallon drum 

of liquid IDW and were stored inside the hangar. The soil and liquid IDW was not sampled and 

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

location. 

Other solids such as spent personal protective equipment (PPE), 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 5.1 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 sulfonate (6:2 FTS)

• 8:2 fluorotelomer sulfonate (8:2 FTS)

• Perfluorohexanoic acid (PFHxA)

• Perfluorohexanesulfonic acid (PFHxS)

• Perfluorononanoic acid (PFNA)
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• N-ethyl 

perfluorooctanesulfonamidoacetic acid 

(NEtFOSAA)

• N-methyl 

perfluorooctanesulfonamidoacetic acid 

(NMeFOSAA)

• Perfluorobutyrate (PFBA)

• Perfluorobutanesulfonic acid (PFBS)

• Perfluorodecanoic acid (PFDA)

• Perfluorododecanoic acid (PFDoA)

• Perfluoroheptanoic acid (PFHpA)

• 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, pH by USEPA Method 

9045D, and grain size by ASTM International D-422.

5.8 Deviations from SI QAPP Addendum

Derivations from the SI QAPP Addendum occurred based on field conditions and discussion 

between AECOM, ARNG, and USACE. Deviations from the SI QAPP Addendum are noted below

and are documented in the following appendices:

• The SI QAPP Addendum stated that three soil samples were to be collected from each 

direct-push boring location at representative depths of the surface soil, vadose soil, and 

intermediate soil. However, four out of the nine direct-push locations (AOI01-01, AOI02-02, 

AOI02-04, and AOI02-05), located on the eastern side of the facility, had very shallow 

depths-to-water, ranging from 5 to 6 feet bgs. Therefore, soil samples at these four borings 

could only be collected in two intervals (0-2 feet bgs and 3-5 feet bgs) instead of three 

intervals. This action was documented in the Log of Daily Notice of Field Activities provided 

in Appendix B1. 

• The SI QAPP Addendum stated that each soil boring location must be cleared to 5 feet bgs 

using a hand auger prior to direct-push technology. At location AOI01-02, clearing to 5 feet 

bgs with a hand auger was not possible due to the presence of pea gravel under the topsoil. 

The location of AOI01-02 was relocated approximately 64 feet north of the original location 

presented in the SI QAPP Addendum. The updated sample location is shown on Figure 

5.1.This action was documented in the Field Change Request Forms provided in Appendix 

B3.
Site Inspection Report

West Bend AASF #1 and Armory, West Bend, Wisconsin

AECOM 5-6

THIS PAGE INTENTIONALLY BLANK
Table 5-1

Site Inspection Samples by Medium

Site Inspection Report, West Bend AASF #1 and Armory

Sample Identification

Sample

Collection 

Date

Sample Depth 

(feet bgs)

PFAS by LC/MS/MS compliant with QSM 5.1 Table B-15TOC(USEPA Method 9060A)pH (USEPA Method 9045D)Grain Size (ASTM D-422)

Comments

AOI01-01-SB-0-2 10/28/2020 0-2 x

AOI01-01-SB-6-8 10/28/2020 6-8 x x x

AOI01-01-SB-6-8-FD 10/28/2020 6-8 x x x Field Duplicate

AOI01-01-SB-10-12 10/28/2020 10-12 x

AOI01-02-SB-0-2 10/28/2020 0-2 x

AOI01-02-SB-5-7 10/28/2020 5-7 x

AOI01-02-SB-7-9 10/28/2020 7-9 x

AOI01-02-SB-7-9-MS 10/28/2020 7-9 x Matrix Spike

AOI01-02-SB-7-9-MSD 10/28/2020 7-9 x Matrix Spike Duplicate

AOI01-03-SB-0-2 10/27/2020 0-2 x

AOI01-03-SB-6-8 10/27/2020 6-8 x

AOI01-03-SB-6-8-FD 10/27/2020 6-8 x Field Duplicate

AOI01-03-SB-15-17 10/27/2020 15-17 x

AOI01-04-SB-0-2 10/28/2020 0-2 x

AOI01-04-SB-6-8 10/28/2020 6-8 x

AOI01-04-SB-13-15 10/28/2020 13-15 x

AOI01-04-SB-13-15-FD 10/28/2020 13-15 x Field Duplicate

AOI02-01-SB-0-2 10/27/2020 0-2 x

AOI02-01-SB-3-5 10/27/2020 3-5 x

AOI02-02-SB-0-2 10/27/2020 0-2 x

AOI02-02-SB-0-2-FD 10/27/2020 0-2 x Field Duplicate

AOI02-02-SB-3-5 10/27/2020 3-5 x

AOI02-03-SB-0-2 10/27/2020 0-2 x

AOI02-03-SB-3-5 10/27/2020 3-5 x

AOI02-03-SB-7-9 10/27/2020 7-9 x

AOI02-04-SB-0-2 10/27/2020 0-2 x

AOI02-04-SB-3-5 10/27/2020 3-5 x x x

AOI02-04-SB-3-5-MS 10/27/2020 3-5 x x Matrix Spike

AOI02-04-SB-3-5-MSD 10/27/2020 3-5 x x Matrix Spike Duplicate

AOI02-05-SB-0-2 10/27/2020 0-2 x

AOI02-05-SB-3-5 10/27/2020 3-5 x

AOI02-SS01 10/26/2020 0-2 x

AOI02-SS02 10/26/2020 0-2 x

AOI02-SS03 10/26/2020 0-2 x

AOI02-SS03-FD 10/26/2020 0-2 x Field Duplicate

AOI02-SS04 10/26/2020 0-2 x

AOI02-SS05 10/26/2020 0-2 x

AOI02-SS05-MS 10/26/2020 0-2 x Matrix Spike

AOI02-SS05-MSD 10/26/2020 0-2 x Matrix Spike Duplicate

AOI02-SS06 10/26/2020 0-2 x

AOI01-01-GW 10/29/2020 20-25 x

AOI01-02-GW 10/28/2020 15-20 x

AOI01-03-GW 10/28/2020 16-21 x

AOI01-04-GW 10/28/2020 15-20 x

AOI02-01-GW 10/27/2020 5-10 x

AOI02-01-GW-MS 10/27/2020 5-10 x Matrix Spike

AOI02-01-GW-MSD 10/27/2020 5-10 x Matrix Spike Duplicate

AOI02-02-GW 10/27/2020 5-10 x

AOI02-03-GW 10/28/2020 20-25 x

AOI02-04-GW 10/27/2020 5-10 x

AOI02-05-GW 10/27/2020 5-10 x

AOI02-05-GW-FD 10/27/2020 5-10 x Field Duplicate

Soil Samples

Groundwater Samples

AECOM 5-7
Table 5-1

Site Inspection Samples by Medium

Site Inspection Report, West Bend AASF #1 and Armory

Sample Identification

Sample

Collection 

Date

Sample Depth 

(feet bgs)

PFAS by LC/MS/MS compliant with QSM 5.1 Table B-15TOC(USEPA Method 9060A)pH (USEPA Method 9045D)Grain Size (ASTM D-422)

Comments

WB-DECON-20200921 9/21/2020 NA x Decontamination Water Blank

WB-FRB-01 10/28/2020 NA x Field Reagent Blank

WB-ERB-01 10/28/2020 NA x Equipment Rinsate Blank

WB-ERB-02 10/26/2020 NA x Equipment Rinsate Blank

Notes:

AASF = Army Aviation Support Facility

AOI = Area of Interest

ASTM = American Society for Testing Materials

bgs = below ground surface

DECON = decontamination water blank

ERB = equipment rinsate blank

FD = field duplicate

FRB = field reagent blank

GW = groundwater

LC/MS/MS = liquid chromatography tandem mass spectrometry

MS/MSD = matrix spike/ matrix spike duplicate

NA = not applicable

PFAS = per- and polyfluoroalkyl substances

pH = potential for hydrogen

QSM = Quality Systems Manual

SB = soil boring

SS = surface soil

TOC = total organic carbon

USEPA = United States Environmental Protection Agency

WB = water blank

Blank Samples

AECOM 5-8
Table 5-2

Soil Boring Depths and Temporary Well Screen Intervals Site 

Inspection Report, West Bend AASF #1 and Armory

Area of Interest Soil Boring ID Soil Boring Depth 

(feet bgs)

Temporary Well 

Screen Interval

(feet bgs)

Groundwater 

Elevation

(feet amsl)

AOI01-01 25 20-25 865.93

AOI01-02 20 15-20 861.45

AOI01-03 21 16-21 865.56

AOI01-04 20 15-20 867.26

AOI02-01 10 5-10 875.94

AOI02-02 10 5-10 875.82

AOI02-03 25 20-25 868.47

AOI02-04 10 5-10 876.00

AOI02-05 10 5-10 874.32

Notes:

AASF = Army Aviation Support Facility

AOI = Area of Interest

bgs = below ground surface

ID = identification

amsl = above mean sea level

AOI 1

AOI 2

AECOM 5-9
Table 5-3

Groundwater Elevations at Temporary Groundwater Monitoring Wells

Site Inspection Report, West Bend AASF #1 and Armory

Monitoring Well ID Ground Surface 

Elevation (ft amsl)

Depth to Water 

(ft bgs)

Groundwater 

Elevation (ft amsl)

AOI01-01 879.63 13.7 865.93

AOI01-02 872.15 10.7 861.45

AOI01-03 870.16 4.6 865.56

AOI01-04 880.26 13.0 867.26

AOI02-01 879.14 3.2 875.94

AOI02-02 879.62 3.8 875.82

AOI02-03 878.47 10.0 868.47

AOI02-04 879.60 3.6 876.00

AOI02-05 878.72 4.4 874.32

Notes:

AASF = Army Aviation Support Facility

AOI = Area of Interest

amsl = above mean sea level

bgs = below ground surface

ft = feet

ID = identification

AECOM 5-10
!?

!?

!?

!? !?

!?

!?

!?

!?

"S"S"S"S"S"S

AOI01-01

AOI01-02

AOI01-03

AOI02-03 AOI02-02

AOI02-05

AOI01-04

Milwaukee River

Wingate Creek

Former Firetruck

Storage

Fire Supression System

Testing

TriMax

Release

AOI 1

AOI 2

CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

SI

3/29/2021

3/29/2021

Site Inspection for PFAS at West Bend, WI

3/29/2021

1:4,200 ­ Figure 5-1 PM CM 3/29/2021

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\WI\West_Bend_Figures\West_Bend_SI_Figures\SI_Report\Fig_5-1_West_Bend_SI_Sample_Locations.mxd

0 175 350 700

Feet

Legend

!? Soil Boring/DPT Temp

Monitoring Wells

"S Surface Soil Sample

Area of Interest

Potential PFAS Release

No Suspected Release

Facility Boundary

Water Body

River/Stream

Surface Water Flow

Direction

Local Groundwater Flow

Direction

!?

!?

"S

"S

"S

"S

"S

"S

TriMax

Release

AOI 2

AOI02-01

AOI02-04

AOI02-SS01

AOI02-SS02

AOI02-SS03

AOI02-SS04

AOI02-SS05

AOI02-SS06

AECOM 5-11
Site Inspection Report

West Bend AASF #1 and Armory, West Bend, Wisconsin

AECOM 5-12

THIS PAGE INTENTIONALLY BLANK
Site Inspection Report

West Bend AASF #1 and Armory, West Bend, Wisconsin

AECOM 6-1

6. Site Inspection Results

This section presents the analytical results of the SI for each AOI. The SLs used in this evaluation 

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

through Section 6.9. Table 6-2 through Table 6-4 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 a RI, the next 

phase under CERCLA. The SLs apply to three compounds, PFOA, PFOS, and PFBS, for both 

soil and groundwater, as presented in Table 6-1. 

All other results presented in this report are considered informational in nature and serve as an 

indication as to whether soil, groundwater, sediment, and surface water 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

PFOA 130 1,600 40

PFOS 130 1,600 40

PFBS 130,000 1,600,000 40,000

Notes:

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

Groundwater and Soil using USEPA’s Regional Screening Level Calculator. Hazard Quotient (HQ) = 0.1. 15 

October 2019.

b.) If only one PFAS is present, a HQ of 1 applies and the values presented would increase by a factor of x10.

c.) μg/kg= micrograms per kilogram

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 
Site Inspection Report

West Bend AASF #1 and Armory, West Bend, Wisconsin

AECOM 6-2

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 one potential PFAS release area: Fire Suppression System Testing area at the 

main hangar. The detected compounds in soil and groundwater are summarized on Table 6-2

through Table 6-4. The detections of PFOS and PFOA in soil and groundwater are presented on 

Figure 6-1 through Figure 6-3. 

6.3.1 AOI 1 Soil Analytical Results

Soil was sampled at AOI 1 from three depth intervals at boring locations AOI01-1, AOI01-02, 

AOI01-03, and AOI01-04 during the SI: shallow interval (0 to 2 feet bgs), intermediate interval (6 

to 8 feet bgs), and deep interval (7 to 17 feet bgs). PFOS, PFOA, and PFBS were detected in soil

at concentrations several orders of magnitude lower than the SLs. 

PFOS was detected in the shallow soil interval at all four locations with concentrations ranging 

from 0.220 J micrograms per kilogram (μg/kg) to 0.827 J μg/kg but not detected in the intermediate 

or deep intervals. PFOA was detected in the shallow soil interval at all four locations with 

concentrations ranging from 0.214 J μg/kg to 0.380 J μg/kg. PFOA was detected in the 

intermediate and deep soil intervals at AOI01-01 with concentrations of 0.606 J μg/Kg and 0.504 

J μg/kg, respectively. PFBS was detected in the shallow soil interval at location AOI01-02 with a 

concentration of 3.41 μg/kg but was not detected in the intermediate or deep soil intervals. 

6.3.2 AOI 1 Groundwater Analytical Results 

Groundwater samples were collected from four temporary monitoring well locations at AOI 1 

during the SI (AOI01-01-GW, AOI01-02-GW, AOI01-03-GW, and AOI01-04-GW). PFOS was 

detected below the SL of 40 nanograms per liter (ng/L), with concentrations ranging from 1.33 J 

ng/L to 18.3 J ng/L, with the maximum concentration occurring at AOI01-01-GW. The SL of 40 

ng/L for PFOA was exceeded at AOI01-01-GW with a concentration of 990 ng/L. PFBS was 

detected below the SL of 40,000 ng/L at two well locations, with concentrations ranging from 0.860 

J ng/L to 1.34 ng/L, with the maximum concentration occurring at AOI01-03-GW. 

6.3.3 AOI 1 Conclusions

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

at AOI 1. The detected concentrations of PFOA, PFOS, and PFBS in soil were several orders of 

magnitude lower than the soil SLs. PFOA was detected in groundwater at a concentration

exceeding the SL of 40 ng/L at the potential source area. The detected concentrations of PFOS 

and PFBS in groundwater were below their respective SLs. Based on the exceedances of the SL 

for PFOA in groundwater, further evaluation at AOI 1 is warranted.

6.4 AOI 2 

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

2, which includes one potential PFAS release area: Tri-MaxTM Release. The detected compounds 

in soil and groundwater are summarized on Table 6-2 through Table 6-4. The detections of PFOS 

and PFOA in soil and groundwater are presented on Figure 6-1 through Figure 6-3. 
Site Inspection Report

West Bend AASF #1 and Armory, West Bend, Wisconsin

AECOM 6-3

6.4.1 AOI 2 Soil Analytical Results

Soil was sampled at AOI 2 from two depth intervals at boring locations AOI02-01, AOI02-02, 

AOI02-04, and AOI02-05 during the SI: shallow interval (0 to 2 feet bgs) and intermediate interval 

(3 to 5 feet bgs); from three depth intervals at boring location AOI02-03: shallow interval (0 to 2 

feet bgs), intermediate interval (3 to 5 feet bgs), and deep interval (7 to 9 feet bgs); and from one 

depth interval at AOI02-SS01, AOI02-SS02, AOI02-SS03, AOI02-SS04, AOI02-SS05, and AOI02-

SS06: shallow (0 to 2 feet bgs). PFOS, PFOA, and PFBS were detected in soil at concentrations 

an order of magnitude lower than the SLs. 

PFOS was detected in the shallow soil interval at all eleven locations with concentrations ranging 

from 0.828 J μg/kg to 6.85 μg/kg. PFOS was detected in the intermediate soil interval at AOI01-

01, AOI02-03, AOI02-04, and AOI02-05 with concentrations ranging from 0.344 J μg/kg to 5.75

μg/kg. PFOS was not detected in the deep interval. PFOA was detected in the shallow soil interval 

at AOI02-01, AOI02-03, AOI02-04, and AOI02-05 locations with concentrations ranging from 

0.163 J μg/kg to 0.262 J μg/kg, but was not detected in the intermediate or deep intervals. PFBS

was not detected in soil at AOI 2.

6.4.2 AOI 2 Groundwater Analytical Results

Groundwater samples were collected from five temporary monitoring well locations at AOI 2 

during the SI (AOI02-01-GW, AOI02-02-GW, AOI02-03-GW, AOI02-04-GW, and AOI02-05-GW). 

The SL of 40 ng/L for PFOS was exceeded at AOI02-01-GW, AOI02-02-GW, AOI02-04-GW, and 

AOI2-05-GW, and AOI02-05-GW-FD with concentrations of 702 J- ng/L, 232 ng/L, 492 ng/L, 225 

ng/L, and 193 ng/L, respectively. PFOA was detected below the SL of 40 ng/L at all well locations 

with concentrations ranging from 3.29 J ng/L to 21.0 ng/L, with the maximum concentration 

occurring at AOI02-02-GW. PFBS was detected below the SL of 40,000 ng/L at all well locations,

with concentrations ranging from 1.44 J ng/L to 8.12 ng/L, with the maximum concentration 

occurring at AOI02-03. 

6.4.3 AOI 2 Conclusions

Based on the results of the SI, PFOA and PFOS were detected in soil at AOI 2; however, the 

detected concentrations were an order of magnitude lower than the soil SLs. PFOS was detected 

in groundwater at concentrations exceeding the individual SL of 40 ng/L at the potential source 

area. The detected concentrations of PFOAand PFBS in groundwater were below their respective

SLs. Based on the exceedances of the SL for PFOS in groundwater, further evaluation at AOI 2

is warranted. 
Site Inspection Report

West Bend AASF #1 and Armory, West Bend, Wisconsin

AECOM 6-4

THIS PAGE INTENTIONALLY BLANK
Table 6-2

PFAS Detections in Surface Soil

Site Inspection Report, West Bend AASF #1 and Armory

Analyte OSD Screening 

Level a

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

6:2 FTS - 51.5 J- 0.210 J ND ND ND ND ND ND ND ND

PFBA - 0.992 J 0.398 J 0.317 J ND ND ND ND ND ND 0.226 J

PFBS 130000 ND 3.41 ND ND ND ND ND ND ND ND

PFDA - 0.137 J 0.357 J ND ND ND ND ND ND ND ND

PFDoA - ND 0.394 J ND ND ND ND ND ND ND ND

PFHpA - 0.568 J ND ND ND ND ND ND ND ND ND

PFHxA - 3.53 ND ND ND ND ND ND ND ND ND

PFHxS - ND ND ND ND ND ND ND 2.56 ND ND

PFNA - 0.426 J 0.188 J ND ND ND 0.156 J 0.137 J ND 0.111 J ND

PFOA 130 0.380 J 0.250 J 0.214 J 0.228 J 0.262 J ND ND 0.163 J 0.177 J 0.188 J

PFOS 130 0.220 J 0.827 J 0.474 J 0.598 J 5.53 3.76 4.56 4.35 6.85 4.51

PFPeA - 6.70 0.252 J ND 0.184 J ND ND ND ND ND ND

PFUnDA - ND 0.369 J ND ND ND ND ND ND ND ND

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

6:2 FTS 6:2 fluorotelomer sulfonate

PFAS per- and polyfluoroalkyl substances

PFBA perfluorobutanoic acid

PFBS perfluorobutanesulfonic acid

References PFDA perfluorodecanoic acid

PFDoA perfluorododecanoic acid

PFHpA perfluoroheptanoic acid

PFHxA perfluorohexanoic acid

PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

Interpreted Qualifiers PFOS perfluorooctanesulfonic acid

J = Estimated concentration PFPeA perfluoropentanoic acid

J- = Estimated concentration, biased low PFUnDA perfluoro-n-undecanoic acid

Acronyms and Abbreviations

AASF Army Aviation Support Facility

AOI Area of Interest

FD Duplicate

ft feet

HQ Hazard quotient

ID identification

LCMSMS Liquid Chromatography Mass Spectrometry

ND Analyte not detected above the LOD

OSD Office of the Secretary of Defense

QSM Quality Systems Manual

Qual Interpreted Qualifier

SB soil boring

USEPA United States Environmental Protection Agency

μg/Kg micrograms per Kilogram

- Not applicable

a. Assistant Secretary of Defense, 2019. Risk Based Screening Levels Calculated for PFOS, PFOA, PFBS 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.

AOI02-05-SB-0-2

10/27/2020

0 - 2 ft

Soil, PFAS by LCMSMS Compliant with QSM 5.1 Table B-15 (μg/Kg)

AOI02-03-SB-0-2

10/27/2020

0 - 2 ft

AOI02-04-SB-0-2

10/27/2020

0 - 2 ft

AOI02-02-SB-0-2

0 - 2 ft

AOI02-01-SB-0-2

10/27/2020

0 - 2 ft

AOI02

10/27/2020

0 - 2 ft

AOI02-02-SB-0-2-FD

10/27/2020

0 - 2 ft

Area of Interest

Sample ID

Sample Date

Depth

AOI01-01-SB-0-2

10/28/2020

0 - 2 ft

AOI01

AOI01-02-SB-0-2

10/28/2020

0 - 2 ft

AOI01-03-SB-0-2

10/27/2020

0 - 2 ft

AOI01-04-SB-0-2

10/28/2020

AECOM 6-5
Table 6-2

PFAS Detections in Surface Soil

Site Inspection Report, West Bend AASF #1 and Armory

Analyte OSD Screening 

Level a

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

6:2 FTS - ND ND ND ND ND ND ND

PFBA - 0.161 J 0.245 J 0.179 J 0.181 J 0.215 J 0.217 J 0.239 J

PFBS 130000 ND ND ND ND ND ND ND

PFDA - ND ND ND ND ND ND ND

PFDoA - ND ND ND ND ND ND ND

PFHpA - ND ND ND ND ND ND UJ ND

PFHxA - ND ND ND ND ND ND ND

PFHxS - 0.182 J ND ND ND ND 0.298 J ND

PFNA - ND ND ND ND ND ND ND

PFOA 130 ND ND ND ND ND ND ND

PFOS 130 2.07 1.32 0.828 J 1.17 2.00 5.27 J- 2.68

PFPeA - ND ND ND ND ND ND ND

PFUnDA - ND ND ND ND ND ND ND

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

6:2 FTS 6:2 fluorotelomer sulfonate

PFAS per- and polyfluoroalkyl substances

PFBA perfluorobutanoic acid

PFBS perfluorobutanesulfonic acid

References PFDA perfluorodecanoic acid

PFDoA perfluorododecanoic acid

PFHpA perfluoroheptanoic acid

PFHxA perfluorohexanoic acid

PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

Interpreted Qualifiers PFOS perfluorooctanesulfonic acid

J = Estimated concentration PFPeA perfluoropentanoic acid

J- = Estimated concentration, biased low PFUnDA perfluoro-n-undecanoic acid

Acronyms and Abbreviations

AASF Army Aviation Support Facility

AOI Area of Interest

FD Duplicate

ft feet

HQ Hazard quotient

ID identification

LCMSMS Liquid Chromatography Mass Spectrometry

ND Analyte not detected above the LOD

OSD Office of the Secretary of Defense

QSM Quality Systems Manual

Qual Interpreted Qualifier

SS surface soil

USEPA United States Environmental Protection Agency

μg/Kg micrograms per Kilogram

- Not applicable

Soil, PFAS by LCMSMS Compliant with QSM 5.1 Table B-15 (μg/Kg)

a. Assistant Secretary of Defense, 2019. Risk Based Screening Levels Calculated for PFOS, PFOA, PFBS 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.

AOI02-SS05

10/26/2020

0 - 2 ft

AOI02-SS06

10/26/2020

0 - 2 ft

AOI02-SS03-FD

10/26/2020

0 - 2 ft

AOI02-SS04

Area of Interest

Sample ID

Sample Date

Depth

AOI02-SS01

10/26/2020

0 - 2 ft

AOI02

10/26/2020

0 - 2 ft

AOI02-SS02

10/26/2020

0 - 2 ft

AOI02-SS03

10/26/2020

0 - 2 ft

AECOM 6-6
Table 6-3

PFAS Detections in Subsurface Soil

Site Inspection Report, West Bend AASF #1 and Armory

Analyte OSD Screening 

Level a

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

6:2 FTS - 104 J- 122 J- ND ND ND ND ND ND ND

8:2 FTS - 1.04 J ND ND ND ND ND ND ND ND

PFBA - 1.95 2.77 ND ND ND ND ND ND ND

PFHpA - 1.16 J 1.05 J ND ND ND ND ND ND ND

PFHxA - 11.5 22.7 ND ND ND ND ND ND ND

PFHxS - ND ND ND ND ND ND ND ND ND

PFNA - 0.168 J ND ND ND ND ND ND ND ND

PFOA 1600 0.606 J 0.504 J ND ND ND ND ND ND ND

PFOS 1600 ND ND ND ND ND ND ND ND ND

PFPeA - 15.2 12.8 ND ND ND ND ND ND ND

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

6:2 FTS 6:2 fluorotelomer sulfonate

8:2 FTS 8:2 fluorotelomer sulfonate

PFAS per- and polyfluoroalkyl substances

PFBA perfluorobutanoic acid

PFBS perfluorobutanesulfonic acid

References PFHpA perfluoroheptanoic acid

PFHxA perfluorohexanoic acid

PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

PFPeA perfluoropentanoic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AASF Army Aviation Support Facility

J- = Estimated concentration, biased low AOI Area of Interest

FD Duplicate

ft feet

HQ Hazard quotient

ID identification

LCMSMS Liquid Chromatography Mass Spectrometry

ND Analyte not detected above the LOD

OSD Office of the Secretary of Defense

QSM Quality Systems Manual

Qual Interpreted Qualifier

SB soil boring

USEPA United States Environmental Protection Agency

μg/Kg micrograms per Kilogram

- Not applicable

Area of Interest

Sample ID

Sample Date

Depth

AOI01-01-SB-6-8

10/28/2020

6 - 8 ft

AOI01

AOI01-02-SB-7-9

10/28/2020

7 - 9 ft

AOI01-03-SB-6-8

10/27/2020

6 - 8 ft

AOI01-01-SB-10-12

10/28/2020

a. Assistant Secretary of Defense, 2019. Risk Based Screening Levels Calculated for PFOS, PFOA, PFBS 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.

Soil, PFAS by LCMSMS Compliant with QSM 5.1 Table B-15 (μg/Kg)

AOI01-04-SB-13-15

10/28/2020

13 - 15 ft

AOI01-04-SB-13-15-FD

10/28/2020

13 - 15 ft

AOI01-03-SB-6-8-FD

10/27/2020

6 - 8 ft

AOI01-04-SB-6-8

10/28/2020

10 - 12 ft 6 - 8 ft

AOI01-02-SB-5-7

10/28/2020

5 - 7 ft

AECOM 6-7
Table 6-3

PFAS Detections in Subsurface Soil

Site Inspection Report, West Bend AASF #1 and Armory

Analyte OSD Screening 

Level a

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

6:2 FTS - ND ND 0.314 J 0.862 J ND ND

8:2 FTS - ND ND ND ND ND ND

PFBA - ND ND ND ND ND 0.196 J

PFHpA - ND ND ND ND ND ND

PFHxA - ND ND ND ND 0.194 J ND

PFHxS - ND ND ND 0.678 J ND ND

PFNA - ND ND ND ND ND ND

PFOA 1600 ND ND ND ND ND ND

PFOS 1600 5.75 0.344 J ND ND 1.14 J 0.671 J

PFPeA - ND ND ND ND ND ND

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

6:2 FTS 6:2 fluorotelomer sulfonate

8:2 FTS 8:2 fluorotelomer sulfonate

PFAS per- and polyfluoroalkyl substances

PFBA perfluorobutanoic acid

PFBS perfluorobutanesulfonic acid

References PFHpA perfluoroheptanoic acid

PFHxA perfluorohexanoic acid

PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

PFPeA perfluoropentanoic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AASF Army Aviation Support Facility

J- = Estimated concentration, biased low AOI Area of Interest

FD Duplicate

ft feet

HQ Hazard quotient

ID identification

LCMSMS Liquid Chromatography Mass Spectrometry

ND Analyte not detected above the LOD

OSD Office of the Secretary of Defense

QSM Quality Systems Manual

Qual Interpreted Qualifier

SB soil boring

USEPA United States Environmental Protection Agency

μg/Kg micrograms per Kilogram

- Not applicable

Area of Interest

Sample ID

Sample Date

Depth

AOI02-02-SB-3-5

10/27/2020

3 - 5 ft

AOI02-01-SB-3-5

10/27/2020

3 - 5 ft

AOI02

Soil, PFAS by LCMSMS Compliant with QSM 5.1 Table B-15 (μg/Kg)

a. Assistant Secretary of Defense, 2019. Risk Based Screening Levels Calculated for PFOS, PFOA, PFBS 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.

AOI02-04-SB-3-5

10/27/2020

3 - 5 ft

AOI02-05-SB-3-5

10/27/2020

3 - 5 ft

AOI02-03-SB-3-5

10/28/2020

3 - 5 ft

AOI02-03-SB-7-9

10/28/2020

7 - 9 ft

AECOM 6-8
Table 6-4

PFAS Detections in Groundwater

Site Inspection Report, West Bend AASF #1 and Armory

Analyte OSD Screening 

Level a

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

6:2 FTS - 871000 J ND ND ND ND ND ND ND ND ND

8:2 FTS - 508 J+ ND ND ND ND ND ND ND ND ND

PFBA - 8200 ND ND ND ND ND ND ND ND ND

PFBS 40000 ND 0.860 J 1.34 J ND 2.43 J 3.37 J 8.12 1.97 J 1.44 J 1.84 J

PFDA - 20.9 J ND ND ND ND 1.08 J ND ND ND ND

PFHpA - 4900 ND 1.25 J 1.20 J 2.29 J 17.3 2.14 J 2.03 J 1.85 J 0.933 J

PFHxA - 54700 ND 1.24 J 1.66 J 8.58 16.0 7.72 15.9 3.39 J 3.74 J

PFHxS - ND ND ND ND 66.6 88.1 24.8 33.2 11.8 13.0

PFNA - 117 ND ND ND 2.38 J 17.0 ND ND ND ND

PFOA 40 990 ND 4.03 J 2.51 J 5.88 21.0 4.91 J 7.49 4.78 J 3.29 J

PFOS 40 18.3 J ND 1.64 J 1.33 J 702 J- 232 13.0 492 225 193

PFPeA - 49200 ND 1.82 J 2.40 J 5.96 14.0 5.00 4.17 J 1.79 J 1.25 J

PFTeDA - ND ND ND ND ND UJ ND ND 2.11 J ND ND

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

6:2 FTS 6:2 fluorotelomer sulfonate

8:2 FTS 8:2 fluorotelomer sulfonate

PFAS per- and polyfluoroalkyl substances

PFBA perfluorobutanoic acid

References PFBS perfluorobutanesulfonic acid

PFDA perfluorodecanoic acid

PFHpA perfluoroheptanoic acid

PFHxA perfluorohexanoic acid

PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

Interpreted Qualifiers PFPeA perfluoropentanoic acid

J = Estimated concentration PFTeDA perfluorotetradecanoic acid

J- = Estimated concentration, biased low

J+ = Estimated concentration, biased high Acronyms and Abbreviations

UJ = The analyte was not detected at a level greater than or equal to the adjusted DL. However, the reported adjusted DL is approximate and may be inaccurate or imprecise. AASF Army Aviation Support Facility

AOI Area of Interest

DL detection limit

FD Duplicate

GW Groundwater

HQ Hazard quotient

ID identification

LCMSMS Liquid Chromatography Mass Spectrometry

LOD Limit of Detection

ND Analyte not detected above the LOD

OSD Office of the Secretary of Defense

QSM Quality Systems Manual

Qual Interpreted Qualifier

USEPA United States Environmental Protection Agency

ng/L nanogram per liter

- Not applicable

AOI02-05-GW-FD

10/27/2020

Water, PFAS by LCMSMS Compliant with QSM 5.1 Table B-15 (ng/L)

AOI02

AOI01-02-GW

10/28/2020

AOI01-03-GW

10/28/2020

Area of Interest

Sample ID

Sample Date

AOI01-01-GW

10/29/2020

a. Assistant Secretary of Defense, 2019. Risk Based Screening Levels Calculated for PFOS, PFOA, PFBS 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.

AOI01

AOI02-04-GW

10/27/2020

AOI02-05-GW

10/27/2020

AOI02-02-GW

10/27/2020

AOI02-03-GW

10/28/2020

AOI01-04-GW

10/28/2020

AOI02-01-GW

10/27/2020

AECOM 6-9
Site Inspection Report

West Bend AASF #1 and Armory, West Bend, Wisconsin

AECOM 6-10

THIS PAGE INTENTIONALLY BLANK 
AOI01-01

AOI01-02

AOI01-03

AOI02-03 AOI02-02

AOI02-05

AOI01-04

0 175 350 700

Feet

Legend

Facility Boundary

Local Groundwater Flow

Direction

PFOS Results (μg/Kg)

ND

>ND - 10

>10 - 130

>130 - 1,600

>1,600

AOI02-04

AOI02-SS01

AOI02-SS02

AOI02-SS03

AOI02-SS04

AOI02-SS05

AOI02-SS06

AOI02-01

12420 Milestone Center Drive

Germantown, MD 20876 Figure 6-1

PFOS Detections in Soil

3/29/2021

3/29/2021

MS 3/29/2021

SI

CM

GIS BY

CHK BY

PM

3/29/2021

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection for PFAS at West Bend, WI

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

Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN,

1:4,200 ­

AOI01-01

AOI01-02

AOI01-03

AOI02-03

AOI02-02

AOI02-01

AOI02-05

AOI01-04

AOI02-04

AOI01-01

AOI01-02

AOI01-03

AOI02-03

AOI01-04

Surface

Intermediate

Deep

AECOM 6-11
AOI01-01

AOI01-02

AOI01-03

AOI02-03 AOI02-02

AOI02-05

AOI01-04

0 175 350 700

Feet

Legend

Facility Boundary

Groundwater Flow Direction

PFOA Results (μg/Kg)

ND

>ND - 10

>10 - 130

>130 - 1,600

>1,600

AOI02-04

AOI02-SS01

AOI02-SS02

AOI02-SS03

AOI02-SS04

AOI02-SS05

AOI02-SS06

AOI02-01

12420 Milestone Center Drive

Germantown, MD 20876 Figure 6-2

PFOA Detections in Soil

3/29/2021

3/29/2021

MS 3/29/2021

SI

CM

GIS BY

CHK BY

PM

3/29/2021

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection for PFAS at West Bend, WI

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

Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN,

1:4,200 ­

AOI01-01

AOI01-02

AOI01-03

AOI02-03

AOI02-02

AOI02-01

AOI02-05

AOI01-04

AOI02-04

AOI01-01

AOI01-02

AOI01-03

AOI02-03

AOI01-04

Surface

Intermediate

Deep

AECOM 6-12
AOI01-01

AOI01-02

AOI01-03

AOI02-03 AOI02-02

AOI02-05

AOI01-04

AOI02-01

AOI02-04

AOI01-01

AOI01-02

AOI01-03

AOI02-03

AOI02-02

AOI02-01

AOI02-05

AOI01-04

AOI02-04

Figure 6-3

PFOS and PFOA Detections in Groundwater

12420 Milestone Center Drive ­ Germantown, MD 20876

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection for PFAS at West Bend, WI

3/30/2021

3/30/2021

3/30/2021

GC

SI

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

3/30/2021

1:4,200

C:\Users\stankevichm\OneDrive - AECOM Directory\ARNG_PFAS_GIS_60552172\MXDs\WI\West_Bend_Figures\West_Bend_SI_Figures\SI_Report\Fig_6-3_West_Bend_SI_GW_PFOS_PFOA_Results.mxd

Legend

Facility Boundary

Local Groundwater Flow 

Direction

0 175 350 700

Feet

PFOS PFOA

PFOS Results (ng/L)

ND - 10

>10 - 40

>40 - 70

>70 - 400

>400

PFOA Results (ng/L)

ND - 10

>10 - 40

>40 - 70

>70 - 400

>400

AECOM 6-13
Site Inspection Report

West Bend AASF #1 and Armory, West Bend, Wisconsin

AECOM 6-14

THIS PAGE INTENTIONALLY BLANK
Site Inspection Report

West Bend AASF #1 and Armory, West Bend, Wisconsin

AECOM 7-1

7. Exposure Pathways

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

presents the current understanding of the site conditions with respect to known and suspected 

sources, potential transport mechanisms and migration pathways, and potentially exposed human 

receptors. A human exposure pathway is considered potentially complete when the following 

conditions are present:

1. Contaminant source;

2. Environmental fate and transport;

3. Exposure point;

4. Exposure route; and

5. Potentially exposed populations.

If any of these elements are missing, the pathway is incomplete. The CSM figures use an empty 

circle symbol to represent an incomplete exposure pathway. Areas with an incomplete pathway 

generally warrant no further action. However, the pathway is considered potentially complete if 

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 (though unlikely due to restricted access), residents outside the facility boundary, and 

recreational users outside of the facility boundary. 

7.1 Soil Exposure Pathway

The SI results for PFOA, PFOS, and PFBS in soil were used to determine whether a potentially 

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

aforementioned criteria.

7.1.1 AOI 1

During the annual testing of the fire suppression system in AOI 1, 20-40 gallons of 3% AFFF were 

dispensed onto the grassy area behind the building, which took place since 2004. The stormwater 

drain within AOI 1 flows through the stormwater system to the south, where it discharges to a 

stormwater basin on the south side of the property. Additionally, if there is flooding at the 

stormwater basin, surface water can overflow to the Milwaukee River.

PFOS, PFOA, and PFBS were detected in soil at AOI 1 and confirm the release of PFAS to soil 

in AOI 1. Based on the results of the SI in AOI 1, ground-disturbing activities could potentially 

result in site worker, future construction worker, and trespasser exposure to PFOS, PFOA, and 

PFBS via inhalation of dust or ingestion of surface soil, and ground-disturbing activities could 

potentially result in future construction worker exposure to subsurface soil. No current 

construction is occurring at AOI 1. The CSM is presented on Figure 7-1. 
Site Inspection Report

West Bend AASF #1 and Armory, West Bend, Wisconsin

AECOM 7-2

7.1.2 AOI 2

There was a one-time training event with one TriMaxTM fire extinguisher that occurred in a grassy 

area on the east side of the Armory. The exact date, amount, and concentration of AFFF used are

unknown. From 1960-1998, there was a drain field to the north of the Armory. Currently, the drain 

field is paved and is used as a parking lot for the facility. The overlying surface water flow from 

the release area is north to the drain field, then west to Wingate Creek, which ultimately 

discharges to the Milwaukee River.

PFOS and PFOA were detected in soil at AOI 2 and confirm the release of PFAS to soil in AOI 2. 

Based on the results of the SI in AOI 2, ground-disturbing activities could potentially result in site 

worker, future construction worker, and trespasser exposure to PFOS and PFOA via inhalation of 

dust or ingestion of surface soil, and ground-disturbing activities could potentially result in future 

construction worker exposure to subsurface soil. No current construction is occurring at AOI 2. 

The CSM is presented on Figure 7-1.

7.2 Groundwater Exposure Pathway

No potable water wells are located within the boundary of West Bend AASF #1 and Armory; 

however, unknown well types exist within 4 miles of the site. Drinking water for West Bend AASF

#1 and Armory is supplied by the City of West Bend, which uses the Lake Michigan and the 

bedrock aquifers as its drinking water source (WIDNR, 2001).

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 each AOI 

based on the aforementioned criteria.

7.2.1 AOI 1

PFOA, PFOS, and PFBS were detected in groundwater from temporary monitoring wells in AOI 

1, confirming the migration of PFAS from soil to groundwater. PFOA exceeded the SL in one 

temporary well in the source area. The incidental groundwater exposure pathway is potentially 

complete for construction workers during trenching activities deep enough to encounter shallow 

groundwater. The exposure pathway is also potentially complete for off-facility residential drinking 

water receptors. The CSM is presented on Figure 7-1.

7.2.2 AOI 2

PFOA, PFOS, and PFBS were detected in groundwater from temporary monitoring wells in AOI 

2, confirming the migration of PFAS from soil to groundwater. PFOS exceeded the SL in two

temporary wells at the source area, one downgradient well, and one upgradient well in AOI 2. The 

incidental groundwater exposure pathway is potentially complete for construction workers during 

trenching activities deep enough to encounter shallow groundwater. The exposure pathway is 

also potentially complete for off-facility residential drinking water receptors. The CSM is presented 

on Figure 7-1.
Media

SOURCE PATHWAY RE

AOI 1 & 

AOI 2

PFAS in 

Surface Soil

Human 

Activities

Precipitation/ 

Run-Off

Leaching/ Infiltration

Airborne Soil 

Particulate

Surface Soil 

at AOI

Surface 

Water/ 

Sediment

Subsurface 

Soil

Shallow 

Groundwater

Source Release Mechanism Media Transport and Migration Media Exposure Routes

Inhalation of 

Dust

IngestionIngestion

Ingestion

Ingestion

Hum

C

/

Figure 

Conceptual S

AOI 1 Fire Suppression S

AOI 2 Tri-MaxT

/

Fire Suppression 

System 

Discharge & 

Tri-MaxTM

Extinguisher 

Release

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

NOTES1. The receptor refers to an off-sitereceptor.2. Inhalation of dust for off-site receptorsis likely insignificant. 3. Human consumption of fishpotentially affected by PFAS is possible.

Site 

Worker

Cons

W

Site 

Worker

Cons

W

/

/ 

LEGEND

Incomplete PathwayPotentially Complete PathwayPotentially Complete Pathway with Exceedance of SLFlow-Chart ContinuesPartial / Possible FlowFlow-Chart Stops

/ 
Site Inspection Report

West Bend AASF #1 and Armory, West Bend, Wisconsin

AECOM 7-4

THIS PAGE INTENTIONALLY BLANK
Site Inspection Report

West Bend AASF #1 and Armory, West Bend, Wisconsin

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

SI field activities included soil and groundwater sampling from 26 October to 28 October 2021. 

Field activities were conducted in accordance with the SI QAPP Addendum (AECOM, 2020b).

To fulfill the project DQOs set forth in the approved SI QAPP Addendum (AECOM, 2019), samples 

were collected and analyzed for a subset of PFAS by LC/MS/MS compliant with QSM Table B-15

as follows. The 18 PFAS analyzed as part of the ARNG SI program are specified in Section 5.8

of this Report.

• Twenty-three (23) soil grab samples from nine (9) boring locations;

• Six (6) soil grab samples from six (6) surface locations; 

• Nine (9) groundwater grab samples from nine (9) temporary well locations; and

• Eighteen (18) QA samples collected.

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 facility 

boundary between source areas and potential drinking water receptors. PFOA in 

groundwater at AOI 1 exceeded the SL of 40 ng/L. PFOS in groundwater at AOI 2

exceeded the SL of 40 ng/L. The detected concentrations of PFOA, PFOS, and PFBS in 

soil samples from all AOIs were below the 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.

AOI 1: Fire Suppression System Testing area and AOI 2: Tri-MaxTM Release were the only 

potential PFAS release areas identified during the PA and examined during the SI. PFOA

was detected in groundwater above the SLs in AOI 1, and PFOS were detected in 

groundwater above the SLs in AOI 2; therefore, these areas may pose a threat to human 

health and the environment.
Site Inspection Report

West Bend AASF #1 and Armory, West Bend, Wisconsin

AECOM 8-2

3. Determine the potential need for a removal action. 

There is a potentially complete pathway between source and off-facility residential drinking 

water receptors. Surficial groundwater at the facility is very shallow, with depth to water 

ranging from 5 to 25 feet bgs. It is unknown if the downgradient domestic and unknowntype wells are screened within the surficial aquifer or the Eastern Dolomite aquifer. The 

Eastern Dolomite aquifer is unconfined at the facility and is particularly vulnerable to 

contamination where the unconsolidated deposits are relatively thin. Vertical cracks and 

cavities may also result in the vertical migration of groundwater.

As described in Section 2.5, in 2021, offsite potable water samples were collected due to 

the exceedance of SLs observed in groundwater during the SI. Five properties were 

selected to be sampled due to their proximity to the facility. PFOA, PFOS, and/or PFBS 

were not detected in all five of the potable water samples collected. A removal action is 

not needed at this time because the potable water sample results were all non-detect. 

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

of a RI.

The geological data collected as part of the SI indicate the shallow subsurface soil has 

relatively low permeability and conductivity with soils dominated by silts and clay. Grain 

size analysis performed at AOI01-03 implies that what presents itself as lean clay in the 

field may in fact be clayey silt (i.e., predominantly silt with a large clay component). This

finding may have profound impacts on the vertical migration of groundwater at the facility 

since silt is more permeable and conductive. Sandy silt (silt with more than 30% sand) is

found in the surface silts in the eastern portion of the facility, around AOI 2. Layers of sanddominated soils can be found at AOI01-04, AOI02-01, AOI02-02, AOI02-04, and AOI02-

05 at thicknesses ranging from 0.5 to 4 feet in thickness. Overall, these data would suggest 

that the subsurface lithology on the eastern and northern portions of the facility are more 

permeable and susceptible to vertical groundwater migration.

Underlying unconsolidated sediments at deeper depths (beyond what was drilled during 

the SI) are anticipated to consist mainly of sands and gravels. Consequently, deeper 

subsurface soils at the facility will likely have higher permeability and conductivity.

Depth to water on the west side of the facility is approximately 15-25 feet bgs, and depth 

to water on the east side of the facility is approximately 5-10 feet bgs in most areas. 

Groundwater flow direction off the facility is south towards the Milwaukee River. These 

geologic and hydrogeologic observations inform development of technical approach for 

the RI. 

5. Identify within 4 miles of the installation other potential PFAS sources (fire stations, major 

manufacturers, other DoD facilities) and receptors, including both groundwater and 

surface water receptors, to determine whether the ARNG is the likely source of PFAS, or 

whether there is an off-facility source of PFAS responsible for installation detections of 

PFAS (USEPA, 2005).

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 source of detected concentrations of PFOA, PFOS, and PFBS at the facility is likely 

attributable to ARNG activities. However, the detected concentration of PFOS at the east 

side of facility boundary suggests an upgradient, off-facility source of PFAS may also be 

contributing to detected PFAS concentrations in surficial groundwater at the facility.

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

West Bend AASF #1 and Armory, West Bend, Wisconsin

AECOM 8-3

Detections of PFOA, PFOS, and PFBS in soil at the source area and facility boundary, 

indicate there is a potentially complete exposure pathway between source and site 

workers, future construction workers, and trespassers. The PFOS and PFOA SL 

exceedances in surficial groundwater indicate there is a potentially complete exposure 

pathway between source and future construction workers and off-facility residents.

PFOA, PFOS, and PFBS were detected in soil and groundwater at source areas and the 

facility boundary indicate a potentially complete pathway between source and receptor. 

However, as described in Section 2.5, offsite potable water samples were collected due 

to the exceedance of SLs observed in groundwater during the SI. Five properties were 

selected to be sampled due to their proximity to the facility. PFOA, PFOS, and PFBS were

not detected in all five of the potable water samples collected.

8.3 Outcome 

Based on the CSMs developed and revised in light of the SI findings, there is potential for 

exposure to off-facility residential drinking water receptors resulting from historical DoD activities

at the facility. Sample chemical 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 in groundwater at AOI 1: Fire Suppression System Testing exceeded the SL of 40

ng/L with a concentration of 990 ng/L at the source area, AOI01-01-GW. Based on the 

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

• PFOS in groundwater at AOI 2: Tri-MaxTM Release exceeded the SL of 40 ng/L in four of 

the well locations with concentrations ranging from 225 ng/L to 702 J- ng/L. Based on the 

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

• The detected concentrations of PFOA, PFOS, and PFBS in soil samples from all AOIs were 

below the 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 off-facility residential 

drinking water receptors caused by DoD activities at or adjacent to 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: Fire Suppression System Testing, and AOI 2: Tri-MaxTM Release.
Site Inspection Report

West Bend AASF #1 and Armory, West Bend, Wisconsin

AECOM 8-4

Table 8-1: Summary of Site Inspection Findings

AOI Potential PFAS 

Release Area

Soil –

Source Area

Groundwater –

Source Area

Groundwater –

Facility 

Boundary

1 Fire Suppression System Testing

2 Tri-MaxTM Release

Legend:

= detected; exceedance of the screening levels

= detected; no exceedance of the screening levels

= not detected

Table 8-2: Site Inspection Recommendations

AOI Description Rationale Future Action

1 Fire Suppression 

System Testing

Exceedances of SLs in groundwater at 

source area. No exceedances of SLs in 

soil. 

Proceed to RI 

2 Tri-MaxTM Release

Exceedances of SLs in groundwater at 

source area. No exceedances of SLs in 

soil.

Proceed to RI
Site Inspection Report

West Bend AASF #1 and Armory, West Bend, Wisconsin

AECOM 9-1

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