FINAL

Site Inspection Report 

Army Aviation Support Facility #3

Peoria, Illinois

Site Inspection for Perfluorooctanoic acid (PFOA), 

Perfluorooctanesulfonic acid (PFOS), Perfluorohexanesulfonic 

acid (PFHxS), Perfluorononanoic acid (PFNA), 

Hexafluoropropylene oxide dimer acid (HFPO-DA), and 

Perfluorobutanesulfonic acid (PFBS) at ARNG Installations, 

Nationwide 

July 2023

Prepared for:

Army National Guard Bureau

111 S. George Mason Drive

Arlington, VA 22204

UNCLASSIFIED
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Table of Contents

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

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

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

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

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

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

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

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

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

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

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

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

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

2.3 History of PFAS Use ...............................................................................................2-3

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

3.1 AOI 1 Tri-Max 30TM Former FTA.............................................................................3-1

3.2 AOI 2 Bulk AFFF Storage .......................................................................................3-1

3.3 AOI 3 Former ANG Firehouse (Building 12) ...........................................................3-1

3.4 AOI 4 Former Metal Plating Facility ........................................................................3-1

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

3.5.1 ILANG...........................................................................................................3-2

3.5.2 Corporate Hangars .......................................................................................3-2

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

6.3 AOI 1 Tri-Max 30TM Former FTA.............................................................................6-2
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6.3.1 AOI 1 Soil Analytical Results ........................................................................6-2

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

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

6.4 AOI 2 Bulk AFFF Storage .......................................................................................6-3

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

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

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

6.5 AOI 3 Former ANG Firehouse (Building 12) ...........................................................6-4

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

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

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

6.6 AOI 4 Former Metal Plating Facility ........................................................................6-6

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

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

6.6.3 AOI 4 Conclusions........................................................................................6-7

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

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

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

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

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

7.1.4 AOI 4 ............................................................................................................7-3

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

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

7.2.2 AOI 2 ............................................................................................................7-4

7.2.3 AOI 3 ............................................................................................................7-4

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

7.3 Surface Water and Sediment Exposure Pathway...................................................7-4

7.3.1 AOI 1 ............................................................................................................7-4

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

7.3.3 AOI 3 ............................................................................................................7-5

7.3.4 AOI 4 ............................................................................................................7-5

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

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

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

9. References.....................................................................................................................9-1
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Army Aviation Support Facility #3, Peoria, Illinois

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Appendices

Appendix A Data Usability Assessment and Validation Reports

Appendix B Field Documentation

B1. Log of Daily Notice of Field Activities

B2. Sampling Forms

B3. Survey Data

B4. Investigation-Derived Waste Polygons

Appendix C Photographic Log

Appendix D TPP Meeting Minutes

Appendix E Boring Logs 

Appendix F Analytical Results

Appendix G Laboratory Reports

Figures

Figure 2-1 Facility Location

Figure 2-2 Facility Topography

Figure 2-3 Groundwater Features

Figure 2-4 Groundwater Elevations, March 2022

Figure 2-5 Surface Water Features

Figure 3-1 Areas of Interest

Figure 5-1 Site Inspection Sample Locations

Figure 6-1 PFOA Detections in Soil

Figure 6-2 PFOS Detections in Soil

Figure 6-3 PFBS Detections in Soil

Figure 6-4 PFHxS Detections in Soil

Figure 6-5 PFNA Detections in Soil

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

Figure 6-7 PFHxS and PFNA Detections in Groundwater

Figure 7-1 Conceptual Site Model, AOI 1

Figure 7-2 Conceptual Site Model, AOI 2

Figure 7-3 Conceptual Site Model, AOI 3

Figure 7-4 Conceptual Site Model, AOI 4

Tables

Table ES-1 Screening Levels (Soil and Groundwater)

Table ES-2 Summary of Site Inspection Findings and Recommendations

Table 5-1 Site Inspection Samples by Medium

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

Elevations

Table 6-1 Screening Levels (Soil and Groundwater)

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

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

Table 6-4 PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Deep Subsurface Soil

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

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

% percent

°C degrees Celsius

°F degrees Fahrenheit

μg/kg micrograms per kilogram

AASF Army Aviation Support Facility

AECOM AECOM Technical Services, Inc.

AFFF aqueous film-forming foam

ANG Air National Guard

AOI Area of Interest

ARNG Army National Guard

bgs below ground surface 

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act 

CoC chain of custody

CSM conceptual site model

DA Department of the Army

DoD Department of Defense

DO dissolved oxygen

DPT direct push technology

DQO data quality objective

DUA data usability assessment

ELAP Environmental Laboratory Accreditation Program

EM Engineer Manual

ERP Environmental Restoration Program

FedEx Federal Express

FTA Fire Training Area

GPS global positioning system

GRPS Ground Penetrating Radar Systems, LLC

HDPE high-density polyethylene 

HFPO-DA hexafluoropropylene oxide dimer acid

IDW investigation-derived waste

ILANG Illinois Air National Guard

ILARNG Illinois Army National Guard

ILEPA Illinois Environmental Protection Agency

ITRC Interstate Technology Regulatory Council

LC/MS/MS liquid chromatography with tandem mass spectrometry

MIL-SPEC military specification

NELAP National Environmental Laboratory Accreditation Program

ng/L nanograms per liter

ORP oxidation-reduction potential

OSD Office of the Secretary of Defense

PA Preliminary Assessment

PFAS per- and polyfluoroalkyl substances

PFBS perfluorobutanesulfonic acid
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Army Aviation Support Facility #3, Peoria, Illinois

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PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

PID photoionization detector

POL petroleum, oil, and lubricants

PQAPP Programmatic UFP-QAPP

PVC polyvinyl chloride

QA quality assurance

QAPP Quality Assurance Project Plan

QC quality control

QSM Quality Systems Manual

SI Site Inspection

SL screening level

SOP standard operating procedure

TOC total organic carbon

TPP Technical Project Planning

UFP Uniform Federal Policy

US United States

USACE United States Army Corps of Engineers

USCS Unified Soil Classification System

USEPA United States Environmental Protection Agency

USFWS United States Fish and Wildlife Service

WWTP wastewater treatment plant
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Army Aviation Support Facility #3, Peoria, Illinois

AECOM ES-1

Executive Summary

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

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

with a focus on the six compounds presented in the memorandum from the Office of the Secretary 

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

listed in the OSD memorandum include perfluorooctane sulfonate (PFOS), perfluorooctanoic acid 

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

hexafluoropropylene oxide dimer acid (HFPO-DA)1, and perfluorobutanesulfonic acid (PFBS).

These compounds are collectively referred to as “relevant compounds” throughout the document

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

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

used, stored, disposed, or released historically (see Table ES-2). The objective of the SI is to 

identify whether there has been a release to the environment from the AOIs identified in the PA 

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

immediate threats, or no further action is required based on SLs for relevant compounds. This SI 

was completed at the Peoria Army Aviation Support Facility (AASF) #3 in Peoria, Illinois and 

determined further evaluation under the Comprehensive Environmental Response, 

Compensation, and Liability Act (CERCLA) is warranted for AOI 1, AOI 2, AOI 3, and AOI 4. Peoria

AASF #3 will also be referred to as the “facility” throughout this document.

The facility is in Peoria County, approximately 5 miles southwest of Peoria, Illinois, and it is 

adjacent to General Wayne A. Downing Peoria International Airport. The facility is constructed on 

a parcel of land that has been leased to the ARNG from the Metropolitan Airport Authority of Peoria 

for a term beginning in 1997 and ending in 2055 (AECOM, 2020). The facility is approximately 44 

acres and currently includes one hangar, a building with connected offices and dry parts storage, 

a small expanse of tarmac south of the hangar, a mobile fuel tanker parking pad (providing 

containment), Petroleum, Oil, and Lubricants storage sheds, and a parking lot for employee’s 

personal vehicles.

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

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

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

for AOI 1, AOI 2, AOI 3, and AOI 4.

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

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

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

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

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

individual chemical of concern in the absence of other PFAS.
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Army Aviation Support Facility #3, Peoria, Illinois

AECOM ES-2

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

Analyteb 

Residential

(Soil)

(μg/kg)a 

0-2 feet bgs

Industrial/ Commercial 

Composite Worker

(Soil)

(μg/kg)a 

2-15 feet bgs

Tap Water

(Groundwater) 

(ng/L)a

PFOA 19 250 6 

PFOS 13 160 4 

PFBS 1,900 25,000 601 

PFHxS 130 1,600 39

PFNA 19 250 6 

Notes:

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

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

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

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

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

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

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

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

AOI

Potential 

PFAS 

Release 

Area

Soil – 

Source Area

Groundwater – 

Source Area

Groundwater – 

Facility 

Boundary 

Future Action

1 Tri-Max 30TM 

FTA

Proceed to RI 

2 Bulk AFFF 

Storage

Proceed to RI

3

Former ANG 

Firehouse 

(Building 12)

Proceed to RI

4

Former 

Metal Plating 

Facility

Proceed to RI

Legend:

N/A = not applicable 

= detected; exceedance of the screening levels

= detected; no exceedance of the screening levels

= not detected
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Army Aviation Support Facility #3, Peoria, Illinois

AECOM 1-1

1. Introduction

1.1 Project Authorization

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

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

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

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

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

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

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

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

acid (PFBS) at ARNG facilities nationwide. The ARNG performed this SI at the Peoria Army 

Aviation Support Facility (AASF) # 3 in Peoria, Illinois. The Peoria AASF is also referred to as the 

“facility” throughout this document.

The SI project elements were performed in compliance with Comprehensive Environmental 

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

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

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

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

investigations.

1.2 SI Purpose

A PA was performed at Peoria AASF # 3 (AECOM Technical Services, Inc. [AECOM], 2020) that

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

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

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

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

no further action is required based on screening levels (SLs) for the relevant compounds.

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

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

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

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

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

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

2.1 Facility Location and Description

The facility is in Peoria County, approximately 5 miles southwest of Peoria, Illinois (Figure 2-1). 

The facility is adjacent to General Wayne A. Downing Peoria International Airport and is accessible 

from the west via South Airport Road.

The facility is constructed on a parcel of land that has been leased to the ARNG from the 

Metropolitan Airport Authority of Peoria for a term beginning in 1997 and ending in 2055 (AECOM, 

2020). From 1947 to 1994, the Illinois Air National Guard (ILANG) operated the facility. In 1994, 

the ILANG moved all assets to a new location across the runway, less than 1 mile west from the 

facility. Prior to the lease in 1997, the Illinois ARNG (ILARNG) used some buildings and tents at 

the facility, although it was considered ILANG property. 

The facility is approximately 44 acres and currently includes one hangar, a building with connected 

offices and dry parts storage, a small expanse of tarmac south of the hangar, a mobile fuel tanker 

parking pad (providing containment), Petroleum, Oil, and Lubricants (POL) storage sheds, and a 

parking lot for employee’s personal vehicles. In recent years, there has been some construction 

that has taken place at the facility. Hangar 23 was demolished sometime between 2012 and 2013 

and is currently a concrete pad. Also, the concrete was replaced primarily on the west and south 

side of the ramp area in 2017.

2.2 Facility Environmental Setting

The facility is within the Illinois River Valley, which is characterized by glacial sediments. The 

facility is bordered to the north, west, and south by the Peoria International Airport and to the east 

by residential and commercial areas (Figure 2-2). The AASF is within 1 mile of the East Branch 

of the Lamarsh Creek and within 4 miles of the Illinois River. The elevation of the facility is 

approximately 509 feet above mean sea level.

2.2.1 Geology

The facility lies within central Illinois, which is underlain by Pleistocene (Cenozoic-era) glacialfluvial sediments. The sediment type and thickness are highly variable in this area. Thick 

sequences of glacial and glacial-fluvial sediments are found in the valleys, and thinner sequences 

of mainly glacial tills and loess are found on the plateaus. 

The facility is underlain by fill material consisting of primarily mixed bedrock and Quaternary-aged 

sediments (Figure 2-3). Underlying the fill is the Quaternary Peoria Silt, which is part of the Mason 

Group. The Peoria Silt is loess and ranges up to more than 20 feet in thickness. The Radnor Till 

Member of the Glasford Formation underlies the Peoria Silt and consists of a silt dominated glacial 

till with some lenses of sand and gravel. The Radnor Till Member is absent in certain areas to the 

west and east of the facility (Sieving, 1997) and may not be encountered directly at the facility.

The uppermost bedrock units in the area are Pennsylvanian-aged rocks of the McLeansboro 

Group (including the Shelburn-Patoka Formations), Carbondale Formation, and Tradewater 

Formation (Sieving, 1997; Leidos, 2015). These formations typically consist of interbedded 

limestones, shales, and sandstones, with coal seams commonly found. Pennsylvanian-aged 

rocks are underlain by a regional unconformity, which overlies Mississippian- to Ordovician-aged 

shale, limestone, and dolostone throughout central Illinois. The bedrock units in the Peoria area 

are sloped to the south-southwest (Leidos, 2015). 
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Army Aviation Support Facility #3, Peoria, Illinois

AECOM 2-2

During the SI, non- to low-plasticity fines (silts) were observed as the dominant lithology of the 

unconsolidated sediments below the Peoria AASF #3. The borings were completed at depths 

between 10 and 30 feet below ground surface (bgs). Varying quantities of sand were noted, 

specifically, isolated layers of silty sand, silty sand with gravel and clayey sand were also observed 

in the borings with thicknesses ranging from 1 to 6 feet. The silt observed in the subsurface is 

consistent with the Peoria Silt. Boring logs are presented in Appendix E.

2.2.2 Hydrogeology

Regionally, groundwater is found in two primary aquifer systems located within the Pleistoceneand Paleozoic-aged aquifers. The Kansan Sankoty Sand aquifer is the most important aquifer for 

industrial and municipal use and is typically first encountered between 15 and 20 feet bgs. This 

aquifer comes within approximately 1.5 miles of the facility to the east of the airport and does not 

underlie the facility (Leidos, 2015). Groundwater in the area can also be sourced from wells as 

deep as 350 feet bgs in Pennsylvanian-aged sandstone, coal, and fractured shale; however, wells 

are generally not drilled into these rocks due to the poor water quality and high mineral content 

(Leidos, 2015). 

Shallow groundwater under the facility is encountered within the glacial drift deposits at depths 

ranging from 3 to 12 feet bgs. During SI activities at the adjacent Peoria Air National Guard (ANG) 

Base in 2017 and 2018, groundwater was encountered between 1.28 and 17.55 feet bgs (Amec 

Foster Wheeler, 2018). Shallow groundwater flow generally reflects surface topography with an 

average hydraulic gradient of 0.013 (Leidos, 2015). Depths to water measured at the AASF in 

March 2022 during the SI ranged from 2.19 to 8.31 feet bgs. Groundwater elevation contours from 

the SI are presented on Figure 2-4 and indicate the groundwater flow direction at the facility is 

primarily to the southeast toward the Illinois River. These data result in a calculated hydraulic 

gradient of 0.013 at the AASF.

There are no wells located within the boundary of the facility; however, there are several 

unidentified wells within a 2-mile radius surrounding the facility (Figure 2-3). The State of Illinois 

does not provide specific well type information (i.e., domestic well, industrial well, etc.). Drinking 

water for the facility is supplied by the City of Bartonville, which is sourced from wells in the 

Sankoty Aquifer, and surface water from the Illinois River (Illinois American Water, 2018). 

2.2.3 Hydrology

The facility is on a plateau west of and approximately 200 feet above the Illinois River. The land 

surface slopes gently to the east on the flight apron and to the north and east in the northern 

portion of the property. There are numerous drainage ditches and storm sewers that collect and 

channel surface water either south toward the East Branch of Lamarsh Creek or east toward 

Kickapoo Creek. Both creeks discharge to the Illinois River, which is approximately 3 miles to the 

east and south of the facility (URS Group Inc., 2009). Surface water features are presented on 

Figure 2-5.

2.2.4 Climate

The climate at the facility consists of four clearly separated seasons, with long, warm summers 

and freezing, snowy, cloudy, windy winters. Temperatures can reach highs of 86 degrees 

Fahrenheit (°F) in the summer months, to lows of 17 °F in winter months. The average annual 

temperature is 51.8 °F. Average precipitation is 36.45 inches of rain (World Climate, 2022).
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Army Aviation Support Facility #3, Peoria, Illinois

AECOM 2-3

2.2.5 Current and Future Land Use

The facility is a controlled access facility with public roads and is adjacent to the Peoria 

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

current land use; however, future infrastructure improvements, land acquisitions, and land use 

controls at the Peoria International Airport are unknown. 

2.2.6 Sensitive Habitat and Threatened/ Endangered Species 

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

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

surrounding area. 

The following plants, insects, and mammals are federally endangered, threatened, proposed, and/ 

or are listed as candidate species in Peoria County, Illinois (US Fish and Wildlife Service

[USFWS], 2022).

• Flowering Plants: Decurrent false aster, Boltonia decurrens (threatened); Eastern prairie 

fringed orchid, Platanthera leucophaea (threatened)

• Insects: Monarch butterfly, Danaus plexippus (candidate); Rusty patched bumble bee, 

Bombus affinis (endangered)

• Mammals: Indiana bat, Myotis sodalis (endangered); Northern Long-Eared Bat, Myotis 

septentrionalis (threatened)

2.3 History of PFAS Use

Four release areas were identified in the PA where AFFF or other PFAS-containing materials may 

have been used, stored, disposed, or released historically at Peoria AASF #3 (AECOM, 2020). 

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

groundwater flow directions. A description of each AOI is presented in Section 3.
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Peoria AASF

­12420 Milestone Center Drive

Germantown, MD 20876

CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

JH

8/1/2022

8/1/2022

PROJECT Site Inspection at Peoria AASF, IL

8/1/2022

1:126,720

PM CM 8/1/2022 Base Map: Sources: Esri, HERE, Garmin, USGS,

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

Figure 2-1

Facility Location

Legend

Facility Boundary

0 1 2 4

Miles

^_

AECOM 2-5 
­12420 Milestone Center Drive

Germantown, MD 20876

CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

JH

8/1/2022

8/1/2022

PROJECT Site Inspection at Peoria AASF, IL

8/1/2022

1:24,000

PM CM 8/1/2022 Base Map: USGS The National Map: National

Boundaries Dataset, 3DEP Elevation Program,

Figure 2-2

Facility Topography

Legend

Facility Boundary

0 1,000 2,000 4,000

Feet

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Figure 2-3

Groundwater Features

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Figure 2-4

Groundwater Elevations,

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Figure 2-5

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Army Aviation Support Facility #3, Peoria, Illinois

AECOM 3-1

3. Summary of Areas of Interest

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

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

identified at Peoria AASF #3 and grouped into four AOIs (AECOM, 2020). The potential release 

areas are shown on Figure 3-1. Figure 3-1 also shows the several adjacent potential sources 

noted in Section 2.3. 

3.1 AOI 1 Tri-Max 30TM Former FTA

Training use of Tri-Max 30TM fire extinguishers (stored at the facility since the late 1990s) occurred 

sometime between 2000 and 2002. During one event, one Tri-Max 30TM fire extinguisher was 

discharged on the ramp area between Pad 5 and 6. Runoff from the ramp flows south, into the 

grassy area immediately adjacent to the ramp, and ultimately into a ditch that drains into the 

stormwater system and to the Illinois River. 

The grassy area south of the ramp is Environmental Restoration Program (ERP) Site 5, which 

was formerly used as a POL storage facility with underground storage tanks, associated piping, 

and drum storage. The final remedial action in 2012 resulted in the removal of soil contaminated 

with petroleum hydrocarbons and chlorinated volatile organic compounds. The excavation 

boundary was approximately 150 feet in diameter and 23 feet deep. The area was backfilled with 

gravel and clean soil (AECOM, 2013). Groundwater remediation was not required and the Illinois 

Environmental Protection Agency (ILEPA) concurred with closing the site in 2013. 

3.2 AOI 2 Bulk AFFF Storage

During the late 1990s, three 6-gallon drums of bulk AFFF concentrate were stored in the POL 

Building. No information was available on the type or concentration of the AFFF stored in the 

drums. During the visual site inspection, the 6-gallon drums of AFFF were not observed at the 

facility. It is unknown if the drums of AFFF were removed from the facility when the Tri-Max 30TM

fire extinguishers were taken to Camp Lincoln in Springfield, Illinois in approximately 2004 or 

2005. There are no drains in the POL Building; however, there is grass/dirt in the surrounding 

area.

3.3 AOI 3 Former ANG Firehouse (Building 12)

Before the ILANG vacated the facility in 1997, Building 12 was utilized as a firehouse by the 

ILANG. ILANG operations at the Firehouse are unknown. The ILANG has been located on the 

Peoria International Airport property since 1947. Because AFFF was introduced to the ANG in the 

1970s and based on findings of the ILANG SI (Amec Foster Wheeler, 2018) conducted at the 

current ILANG location, it is presumed that AFFF was maintained on firetrucks at the firehouse, 

and annual nozzle testing was conducted prior to ILANG moving in 1997. A grassy area exists on 

the north side of the building, with pavement or other buildings on the west, south, and east sides 

of the building. 

3.4 AOI 4 Former Metal Plating Facility

From the 1940s to 1990s, Building 2 was utilized as a metal plating facility. The geographical 

coordinates are 40°39'38.53"N; 89°40'51.64"W. Multiple metals were used in the plating and 

electroplating process such as chromium, cadmium, and zinc. Plating operations commonly 

involve PFAS-containing mist suppressants to reduce the risk of metal fires and prevent worker 

inhalation of metals. There is no knowledge of any AFFF-related activities at this building, and it 
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AECOM 3-2

is possible that PFAS-containing materials were used or stored at some point in Building 2. The 

waste created from the metal plating process was disposed of in the sinks and building drains. It 

is reported that all drains lead to an oil/water separator, located at the wash rack south of AOI 3 

and AOI 4 (Anderson Environmental, 2019), and ultimately to the Greater Peoria sanitary 

wastewater treatment plant (WWTP).

3.5 Adjacent Sources

Twelve off-facility, potential sources were identified adjacent to AASF #3 during the PA and are 

not associated with ARNG activities (AECOM, 2020). The adjacent potential sources are shown 

on Figure 3-1 and described in the following sections for informational purposes only and will not 

be investigated as part of this SI.

3.5.1 ILANG

The ILANG has been located on the Peoria International Airport property since June 1947 when 

the unit was originally organized as the 169th Fighter Squadron. The ILANG leases approximately 

91 acres in the southwest portion of the Peoria International Airport (Amec Foster Wheeler, 2018). 

It is known that many of the buildings have stored AFFF or emergency vehicles that held AFFF, 

and that there has been use and discharge of AFFF on the premises. An SI was completed at the 

182nd Wing of the ILANG at Peoria International Airport (Amec Foster Wheeler, 2018). There are 

ten areas within the existing ILANG property (west of Peoria AASF #3) where PFOA and/or PFOS 

were measured in groundwater at concentrations exceeding the 2016 USEPA Health Advisory 

screening criteria.

3.5.2 Corporate Hangars 

Two private corporate hangars are located near the AASF. One is located approximately 0.85

miles northeast of the AASF and one is located approximately 1.5 miles northwest of the facility.

Both corporate hangars are located upgradient of the facility. The corporate hangars have fire 

suppression systems; however, the type of fire suppressants used in the fire suppression systems

are unknown. The corporate hangars have been identified as a potential adjacent source due to 

the possibility that the fire suppression system contains AFFF. 
Bulk AFFF

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(Building 2)

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(Building 12)

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4. Project Data Quality Objectives

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

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

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

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

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

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

AOIs.

4.1 Problem Statement 

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

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

SLs are presented in Section 6.1 of this report. 

4.2 Information Inputs

Primary information inputs included:

• The PA for Peoria AASF #3 (AECOM, 2020);

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

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

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

parameters measured at the time of sampling.

4.3 Study Boundaries

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

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

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

owner(s). The scope was bounded vertically by the first encountered shallow groundwater at each 

borehole. Temporal boundaries were limited to the spring season, which was the earliest available 

time field resources were available to complete the study. 

4.4 Analytical Approach

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

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

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

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

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

4.5 Data Usability Assessment 

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

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

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

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

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

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

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

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

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

requirements of the SI QAPP Addendum (AECOM, 2021a). 
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5. Site Inspection Activities

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

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

in accordance with the following approved documents: 

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

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

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

• Final Preliminary Assessment Report, Peoria Army Aviation Support Facility #3, Peoria,

Illinois dated August 2020 (AECOM, 2020);

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

Peoria Army Aviation Support Facility #3, Peoria, Illinois dated October 2021 (AECOM,

2021a); and

• Final Site Safety and Health Plan, Peoria Army Aviation Support Facility #3, Peoria, Illinois

dated October 2021 (AECOM, 2021b).

The SI field activities were conducted from 21 to 23 March 2022 and consisted of utility clearance,

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

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

QAPP Addendum (AECOM, 2021a). 

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

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

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

• Thirty-four (34) soil samples from 13 boring locations;

• Eleven (11) grab groundwater samples from 11 temporary well locations;

• Twenty (20) quality assurance (QA)/quality control (QC) samples.

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

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

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

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

Appendix B3, and investigation-derived waste (IDW) polygons are provided in Appendix B4. 

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

5.1 Pre-Investigation Activities

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

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

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

5.1.1 Technical Project Planning

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

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

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

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

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

address the AOIs identified in the PA. 

A combined TPP Meeting 1 and 2 was held on 15 September 2021, prior to SI field activities. The 

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

stakeholders for this SI include the ARNG, ILARNG, USACE and ILEPA. Stakeholders were 

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

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

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

A TPP Meeting 3 will be held on a future date (To Be Determined) after the field event to discuss 

the results of the SI. Meeting minutes for TPP 3 will be included in Appendix D of this report. 

Future TPP meetings will provide an opportunity to discuss the results and findings, and future 

actions, where warranted. 

5.1.2 Utility Clearance

AECOM personnel placed a ticket with the USA north 811 “JULIE” Illinois utility clearance provider 

to notify them of intrusive work on 14 March 2022. Additionally, AECOM contracted Ground 

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

clearance. GPRS performed utility clearance of the proposed boring locations on 21 March 2022 

with input from the AECOM field team and Peoria AASF #3 facility staff. General locating services 

and ground-penetrating radar were used to complete the clearance. The first 5 feet of each boring 

were also pre-cleared using a hand auger to verify utility clearance in shallow subsurface where 

utilities would typically be encountered. 

5.1.3 Source Water and Sampling Equipment Acceptability

Two potable water sources at Peoria AASF #3 were sampled from spigots (PEOR-DECON-01 

and PEOR-DECON-02) on 12 August 2021 to assess usability for decontamination of drilling 

equipment. PEOR-DECON-01 was collected from the eastern exterior wall of the office building 

north of the entrance gate, whereas PEOR-DECON-02 was collected on the northern exterior wall 

of the hangar. Results of the samples collected from both locations confirmed these sources to 

be acceptable for use in this investigation; therefore, they were used throughout the field activities.

Specifically, the samples were analyzed by LC/MS/MS compliant with QSM 5.3 Table B-15. The 

results of the decontamination water samples associated with both sources used during the SI 

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

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

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

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

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

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

member regarding the allowable materials within the sampling environment. 

5.2 Soil Borings and Soil Sampling

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

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

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

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

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

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

locations were adjusted within a 50-foot offset for reasons including drill rig access, utility 
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AECOM 5-3

avoidance, and bias toward sampling within observed drainage features. One boring, PEOR-04, 

was drilled within the approximate excavation boundary of the ERP Site 5. All other borings 

located south of the ramp area were drilled outside of the approximate excavation boundary.

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

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

approximately 2 feet above the groundwater table, and one subsurface soil sample at the midpoint between the surface and the groundwater table. Due to shallow groundwater at AOI02-01, 

only two discrete soil samples were collected, 0 to 2 feet bgs and 3 to 5 feet bgs.

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

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

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

Observations and measurements were recorded on sampling forms (Appendix B2) and in a nontreated field logbook (i.e., composition notebook). Depth interval, recovery thickness, PID 

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

(using the USCS) were recorded. The boring logs are provided in Appendix E. 

Soil borings completed during the SI found non to low plasticity fines (silts) with varying levels of 

sand as the dominant lithology of the unconsolidated sediments below the Peoria AASF #3. The 

borings were completed at depths between 10 and 30 feet bgs. Varying quantities of sand were 

noted, specifically, isolated layers of silty sand, silty sand with gravel and clayey sand were also 

observed in the borings with thicknesses ranging from 1 foot to 6 feet. These observations are 

consistent with the understood depositional environment of the region.

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

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

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

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

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

SI QAPP Addendum (AECOM, 2021a). Grain size samples were not collected during the SI in 

accordance with the SI QAPP because horizontally and/or vertically extensive clay units were not 

encountered.

Field duplicate samples were collected at a rate of 10 percent (%) 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 nondedicated sampling equipment was used, such as a hand auger for the shallow soil samples, 

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

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

preserved at or below 6 degrees Celsius (°C) during shipment.

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

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

of sampling activities. Borings were installed in grass areas to avoid disturbing concrete or asphalt 

surfaces.

5.3 Temporary Well Installation and Groundwater Grab Sampling

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

the borehole was advanced to the desired depth, 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. Temporary well AOI03-01 was constructed using two 5-foot screen sections due 

to the absence of an obvious water-bearing zone, as only a small wet zone at 20 feet bgs was 

identified in the 30-foot boring. The absence of high conductivity zones at AOI03-01 is evidenced 
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AECOM 5-4

by the large drawdown experienced during groundwater sampling. New PVC pipe and screen 

were used to avoid cross contamination between locations. The screen intervals for the temporary 

wells are provided in Table 5-2. 

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

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

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

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

using a PFAS-free marker or pen. The temporary wells were purged at a rate determined in the 

field to reduce turbidity and draw down prior to sampling. Water quality parameters (e.g., 

temperature, specific conductance, pH, dissolved oxygen [DO], and oxidation-reduction potential 

[ORP]) were measured using a water quality meter and recorded on the field sampling form 

(Appendix B2) before each grab sample was collected. Additionally, a subsample of each 

groundwater sample was collected in a separate container, and a shaker test was completed to 

identify if there were any foaming. No foaming was noted in any of the groundwater samples.

Samples were packaged on ice and transported via FedEx under standard CoC procedures to 

the laboratory and analyzed by LC/MS/MS compliant with QSM 5.3 Table B-15 in accordance with 

the SI QAPP Addendum (AECOM, 2021a). 

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

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

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

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

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

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

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

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

location was patched to match existing surrounding conditions.

5.4 Synoptic Water Level Measurements

A synoptic groundwater gauging event was performed on 23 March 2022. Groundwater elevation 

measurements were collected from the 11 new temporary monitoring wells. Water level 

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

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

5.5 Surveying 

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

the SOP guidelines provided in the SI QAPP Addendum (AECOM, 2021a). Survey data from the 

newly installed wells on the facility were collected on 23 March 2022 in the applicable Universal 

Transverse Mercator zone projection with Illinois Coordinate System, West Zone, based on the 

North American Datum of 1983 (NAD83) (horizontal) and North American Vertical Datum 1988 

(vertical). The surveyed well data are provided in Appendix B3. 

5.6 Investigation-Derived Waste 

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

the SI is considered non-hazardous waste and was managed in accordance with the SI QAPP 

Addendum (AECOM, 2021a) and with the Army Guidance for Addressing Releases of PFAS, Q18 

(DA, 2018). 
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Non-hazardous solid IDW (i.e., soil cuttings) generated during SI activities was left in place at the 

point of the source. The soil cuttings were distributed on the downgradient side of the borehole. 

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

containerized in a properly labeled 55-gallon drum and stored on the facility near AOI 2. This IDW 

assumes the PFAS characteristics of the associated groundwater samples collected from at the 

facility. Liquid IDW will be further managed under separate ARNG contract in accordance with the 

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

Geographic coordinates were collected using a global positioning system (GPS) around each 

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

figure in Appendix B4. 

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

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

activities were disposed of at a licensed solid waste landfill.

5.7 Laboratory Analytical Methods

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

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

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

5.8 Deviations from the SI QAPP Addendum

No deviations from the SI QAPP Addendum were identified during the review of field documentation.
Site Inspection Report

Army Aviation Support Facility #3, Peoria, Illinois

AECOM 5-6

THIS PAGE INTENTIONALLY BLANK
Table 5-1

Site Inspection Samples by Medium

Site Inspection Report, Peoria AASF #3, Illinois

Sample Identification

Sample

Collection 

Date/Time

Sample Depth 

(feet bgs)

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

Comments

AOI01-01-SB-0-2 3/22/2022 15:00 0 - 2 x

AOI01-01-SB-4-6 3/22/2022 15:05 4 - 6 x

AOI01-01-SB-8-10 3/22/2022 15:10 8 - 10 x

AOI01-02-SB-0-2 3/22/2022 10:50 0 - 2 x

AOI01-02-SB-0-2-MS 3/22/2022 10:50 0 - 2 x MS

AOI01-02-SB-0-2-MSD 3/22/2022 10:50 0 - 2 x MSD

AOI01-02-SB-4-6 3/22/2022 10:52 4 - 6 x

AOI01-02-SB-8-10 3/22/2022 10:55 8 - 10 x x x

AOI01-03-SB-0-2 3/22/2022 12:00 0 - 2 x

AOI01-03-SB-4-6 3/22/2022 12:05 4 - 6 x

AOI01-03-SB-8-10 3/22/2022 12:10 8 - 10 x

AOI01-04-SB-0-2 3/21/2022 11:00 0 - 2 x

AOI01-05-SB-0-2 3/21/2022 16:40 0 - 2 x

AOI02-01-SB-0-2 3/23/2022 12:00 0 - 2 x

AOI02-01-SB-3-5 3/23/2022 12:10 3 - 5 x x x

AOI03-01-SB-0-2 3/21/2022 17:00 0 - 2 x

AOI03-01-SB-0-2-D 3/21/2022 17:00 0 - 2 x FD

AOI03-01-SB-8-10 3/21/2022 17:05 8 - 10 x x x

AOI03-01-SB-8-10-D 3/21/2022 17:05 8 - 10 x x FD

AOI03-01-SB-8-10-MS 3/21/2022 17:05 8 - 10 x x MS

AOI03-01-SB-8-10-MSD 3/21/2022 17:05 8 - 10 x x MSD

AOI03-01-SB-18-20 3/21/2022 17:10 18 - 20 x

AOI04-01-SB-0-2 3/23/2022 11:20 0 - 2 x

AOI04-01-SB-4-6 3/23/2022 11:30 4 - 6 x

AOI04-01-SB-9-10 3/23/2022 11:35 9 - 10 x

AOI04-02-SB-0-2 3/23/2022 9:30 0 - 2 x

AOI04-02-SB-10-12 3/23/2022 10:10 10 - 12 x x x

AOI04-02-SB-18-20 3/23/2022 10:15 18 - 20 x

PEOR-01-SB-0-2 3/22/2022 13:20 0 - 2 x

PEOR-01-SB-5-7 3/22/2022 13:25 5 - 7 x

PEOR-01-SB-11-13 3/22/2022 13:30 11 - 13 x

PEOR-02-SB-0-2 3/22/2022 17:10 0 - 2 x

PEOR-02-SB-5-7 3/22/2022 17:15 5 - 7 x

PEOR-02-SB-10-12 3/22/2022 17:20 10 - 12 x

PEOR-03-SB-0-2 3/22/2022 16:10 0 - 2 x

PEOR-03-SB-6-8 3/22/2022 16:15 6 - 8 x

PEOR-03-SB-13-15 3/22/2022 16:20 13 - 15 x

PEOR-04-SB-0-2 3/22/2022 9:42 0 - 2 x

PEOR-04-SB-0-2-D 3/22/2022 9:42 0 - 2 x FD

PEOR-04-SB-0-2-MS 3/22/2022 9:42 0 - 2 x MS

PEOR-04-SB-0-2-MSD 3/22/2022 9:42 0 - 2 x MSD

PEOR-04-SB-6-8 3/22/2022 9:48 6 - 8 x

PEOR-04-SB-6-8-D 3/22/2022 9:48 6 - 8 x FD

PEOR-04-SB-13-15 3/22/2022 9:55 13 - 15 x

PEOR-04-SB-13-15-D 3/22/2022 9:55 13 - 15 x FD

Soil Samples

AECOM 5-7 
Table 5-1

Site Inspection Samples by Medium

Site Inspection Report, Peoria AASF #3, Illinois

Sample Identification

Sample

Collection 

Date/Time

Sample Depth 

(feet bgs)

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

Comments

AOI01-01-GW 3/22/2022 16:30 NA x

AOI01-02-GW 3/22/2022 12:18 NA x

AOI01-03-GW 3/22/2022 15:20 NA x

AOI02-01-GW 3/23/2022 13:30 NA x

AOI03-01-GW 3/22/2022 10:05 NA x

AOI03-01-GW-D 3/22/2022 10:05 NA x FD

AOI03-01-GW-MS 3/22/2022 10:15 NA x MS

AOI03-01-GW-MSD 3/22/2022 10:15 NA x MSD

AOI04-01-GW 3/23/2022 11:58 NA x

AOI04-02-GW 3/23/2022 11:30 NA x

PEOR-01-GW 3/22/2022 14:45 NA x

PEOR-01-GW-D 3/22/2022 14:45 NA x FD

PEOR-02-GW 3/23/2022 8:45 NA x

PEOR-03-GW 3/23/2022 9:20 NA x

PEOR-04-GW 3/22/2022 13:00 NA x

PEOR-FRB-01 3/22/2022 10:00 NA x

PEOR-DECON-01 8/12/2021 10:50 NA x from outside spigot

PEOR-DECON-02 8/12/2021 11:00 NA x from outside spigot

PEOR-DECON-03 3/23/2022 10:10 NA x from CTS holding tank

PEOR-ERB-01 3/23/2022 10:25 NA x from hand auger

PEOR-ERB-02 3/23/2022 10:42 NA x from hand auger

PEOR-ERB-03 3/23/2022 12:30 NA x from DPT shoe

PEOR-ERB-04 3/23/2022 12:40 NA x from DPT shoe

Notes:

ASTM = American Society for Testing and Materials

bgs = below ground surface

CTS = Cascade Technical Services, Inc.

ERB = equipment rinsate blank

FD = field duplicate

FRB = field reagent blank

LC/MS/MS = Liquid Chromatography Mass Spectrometry

MS/MSD = matrix spike/ matrix spike duplicate

PFAS = per- and polyfluoroalkyl substances

QSM = Quality Systems Manual

TOC = total organic carbon

USEPA = United States Environmental Protection Agency

Quality Control Samples

Groundwater Samples

AECOM 5-8
Table 5-2

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

Site Inspection Report, Peoria AASF #3, Illinois

Area of 

Interest

Boring 

Location

Soil Boring 

Depth 

(feet bgs)

Temporary Well 

Screen Interval 

(feet bgs)

Top of Casing 

Elevation 

(feet NAVD88)

Ground Surface 

Elevation 

(feet NAVD88)

Depth to 

Water

(feet btoc)

Depth to 

Water

(feet bgs)

Groundwater 

Elevation

(feet NAVD88)

AOI01-01 25 20 - 25 639.97 639.30 7.45 6.78 632.52

AOI01-02 25 20 - 25 638.73 638.20 8.69 8.16 630.04

AOI01-03 25 20 - 25 639.56 639.02 8.85 8.31 630.71

2 AOI02-01 10 5 - 10 647.11 646.70 2.75 2.33 644.36

3 AOI03-01 30 20 - 30 647.53 646.92 5.65 5.03 641.88

AOI04-01 20 15 - 20 646.90 646.42 4.99 4.50 641.91

AOI04-02 25 20 - 25 645.95 645.47 5.50 5.02 640.45

PEOR-01 15 10 - 15 649.35 649.10 2.43 2.19 646.92

PEOR-02 20 15 - 20 643.99 643.38 6.38 5.77 637.61

PEOR-03 20 15 - 20 642.84 642.37 8.55 8.08 634.29

PEOR-04 25 20 - 25 633.44 632.72 5.48 4.76 627.96

Notes:

AASF = Army Aviation Support Facility

AOI = area of interest

bgs = below ground surface

btoc = below top of casing

NAVD88 = North American Vertical Datum 1988

Facilitywide

4

1

AECOM 5-9 
Site Inspection Report

Army Aviation Support Facility #3, Peoria, Illinois

AECOM 5-10

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"S

?!

?!

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?! AOI 2

AOI 3

AOI 1

AOI 4

PEOR-01

PEOR-02

PEOR-03

PEOR-04

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI01-05

AOI02-01

AOI03-01 AOI04-01

AOI04-02

­12420 Milestone Center Drive

Germantown, MD 20876

CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

JH

8/1/2022

8/1/2022

PROJECT Site Inspection at Peoria AASF, IL

8/1/2022

1:3,960

PM CM 8/1/2022 Base Map: Source: Esri, Maxar, Earthstar Geographics,

and the GIS User Community

Figure 5-1

Site Inspection Sample Locations

Legend

?! Soil Boring/Temporary Monitoring Well

"S Surface Soil Location

Area of Interest

Facility Boundary

River/Stream

Surface Water Flow Direction

Groundwater Flow Direction

0 165 330 660

Feet

AECOM 5-11
Site Inspection Report

Army Aviation Support Facility #3, Peoria, Illinois

AECOM 5-12

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Site Inspection Report

Army Aviation Support Facility #3, Peoria, Illinois

AECOM 6-1

6. Site Inspection Results 

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

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

through Section 6.6. Table 6-2 through Table 6-5 present results in soil or groundwater for the 

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

laboratory reports are provided in Appendix G. 

6.1 Screening Levels 

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

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

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

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

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

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

6-1 below.

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

Analyteb 

Residential

(Soil)

(μg/kg)a 

0-2 feet bgs

Industrial/ 

Commercial 

Composite 

Worker 

(Soil)

(μg/kg)a 

2-15 feet bgs

Tap Water

(Groundwater) 

(ng/L)a

PFOA 19 250 6 

PFOS 13 160 4

PFBS 1,900 25,000 601 

PFHxS 130 1,600 39

PFNA 19 250 6 

Notes:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Army Aviation Support Facility #3, Peoria, Illinois

AECOM 6-2

6.2 Soil Physicochemical Analyses

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

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

of the TOC and pH sampling. 

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

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

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

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

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

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

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

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

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

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

6.3 AOI 1 Tri-Max 30TM Former FTA

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

AOI 1: Tri-Max 30TM Former FTA. The soil and groundwater results are summarized on Table 6-2

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

6.3.1 AOI 1 Soil Analytical Results

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

6-4 summarize the soil results.

AOI 1 is located in the middle of the ramp. In order to avoid intrusive activities on the concrete, 

borings were drilled downgradient of the AOI. Soil was sampled from surface soil (0 to 2 feet bgs), 

from AOI01-01 to AOI01-05 and PEOR-04. Soil was also sampled from shallow subsurface soil 

at depths between 4 to 15 feet bgs from AOI01-01 to AOI01-03 and PEOR-04. Deep subsurface 

soil was not collected at AOI 1.

In surface soil, PFOS was detected at all six borings, with concentrations above the SL of 13

micrograms per kilogram (μg/kg) at five of the locations. PFOS concentrations ranged from 2.54 

μg/kg at AOI01-05 to 342 J μg/kg at PEOR-04. PFOA, PFHxS, PFNA, and PFBS were detected 

at concentrations below their respective SLs:

• PFOA and PFNA were detected at all six locations, with concentrations ranging from 

0.153 J μg/kg to 3.53 μg/kg.

• PFHxS was detected at all six boring locations, with concentrations ranging from 0.432

J μg/kg to 41.2 μg/kg.

• PFBS was detected at four of six boring locations, with concentrations ranging from 

0.027 J μg/kg to 0.507 J μg/kg.

PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in shallow subsurface soil at 

concentrations below their respective SLs:

• PFOA was detected in seven of eight samples, with concentrations ranging from 0.109

J μg/kg to 1.54 μg/kg.

• PFOS was detected in seven of eight samples, with concentrations ranging from 1.10 

J μg/kg to 76.4 J μg/kg. 
Site Inspection Report

Army Aviation Support Facility #3, Peoria, Illinois

AECOM 6-3

• PFHxS was detected at in all eight samples, with concentrations ranging from 0.083 J

μg/kg to 19.4 μg/kg.

• PFNA was detected in five of eight samples, with concentrations ranging from 0.025 J 

μg/kg to 1.92 μg/kg.

• PFBS was detected in four of eight samples, with concentrations ranging from 0.048 J 

μg/kg to 0.612 J μg/kg. 

6.3.2 AOI 1 Groundwater Analytical Results

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

summarizes the groundwater results.

Groundwater was sampled from temporary monitoring wells AOI01-01 through AOI01-03 and 

downgradient well PEOR-04. PFOA, PFOS, PFHxS, and PFNA were detected in concentrations 

above their respective SLs:

• PFOA was detected above the SL of 6 nanograms per liter (ng/L) in all four wells, with 

concentrations ranging from 116 ng/L at AOI01-02 to 4,770 ng/L at AOI01-03.

• PFOS was detected above the SL of 4 ng/L in all four wells, with concentrations ranging 

from 17.8 ng/L at AOI01-01 to 7,560 ng/L at AOI01-03.

• PFHxS was detected above the SL of 39 ng/L in all four wells, with concentrations 

ranging from 341 ng/L at AOI01-01 to 7,250 ng/L at AOI01-03. 

• PFNA was detected above the SL of 6 ng/L in three of four wells, with detected 

concentrations ranging from 15.6 ng/L at AOI01-03 to 44.0 ng/L at AOI01-02. PFNA was 

not detected in well AOI01-01.

PFBS was detected below the SL of 601 ng/L in all four wells, with concentrations ranging from 

28.9 ng/L to 210 ng/L.

6.3.3 AOI 1 Conclusions

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

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

Based on the exceedances of the SLs in soil and groundwater, further evaluation at AOI 1 is 

warranted.

6.4 AOI 2 Bulk AFFF Storage

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

AOI 2: Bulk AFFF Storage. The results for soil and groundwater are summarized on Table 6-2

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

6.4.1 AOI 2 Soil Analytical Results

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

Table 6-4 summarize the soil results.

Soil at AOI 2 was sampled from surface soil (0 to 2 feet bgs) and shallow subsurface soil (3 to 5 

feet bgs) at AOI02-01. Deep subsurface soil was not collected at AOI 2 due to the shallow depth 

to groundwater.
Site Inspection Report

Army Aviation Support Facility #3, Peoria, Illinois

AECOM 6-4

In surface soil, PFOS, PFHxS, and PFNA were detected below their respective SLs, with 

concentrations ranging from 0.060 J μg/kg to 1.28 μg/kg; PFOA and PFBS were not detected.

PFOS was detected in shallow subsurface soil below the SL, with a concentration of 0.417 J 

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

samples.

Soil was also sampled from the upgradient boundary location PEOR-01 from the surface (0 to 2 

feet bgs) and shallow subsurface (5 to 7 feet bgs and 11 to 13 feet bgs) intervals. PFOA, PFOS, 

PFHxS, and PFNA were all detected below their respective SLs in surface soil, with 

concentrations ranging from 0.089 J μg/kg to 0.819 J μg/kg; PFBS was not detected. In shallow 

subsurface soil, PFOS and PFHxS were detected below their respective SLs, with concentrations 

ranging from 0.113 J μg/kg to 0.496 J μg/kg. The highest concentrations of PFOS and PFHxS 

were detected at the 11- to 13-foot interval. PFOA, PFNA, and PFBS were not detected in shallow 

subsurface soil.

6.4.2 AOI 2 Groundwater Analytical Results

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

summarizes the groundwater results.

Groundwater was sampled from temporary monitoring well AOI02-01. PFOS was detected above 

the SL of 4 ng/L at a concentration of 28.4 ng/L. PFOA, PFHxS, and PFBS were detected below 

their respective SLs: PFOA at 4.23 ng/L, PFHxS at 38.2 ng/L, and PFBS at 2.70 J ng/L. PFNA 

was not detected in groundwater at AOI 2.

Groundwater was also sampled from the upgradient temporary well PEOR-01. PFOS and PFHxS 

were detected at concentrations above their respective SLs, with concentrations of 8.56 ng/L and 

55.1 ng/L, respectively. PFOA and PFBS were detected below their SLs in groundwater, with 

concentrations of 2.89 J ng/L and 10.5 ng/L, respectively. PFNA was not detected in groundwater 

at PEOR-01.

6.4.3 AOI 2 Conclusions

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

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

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

further evaluation at AOI 2 is warranted. Exceedances in the upgradient PEOR-01 may indicate 

adjacent release areas may be contributing to the concentrations observed at the facility.

6.5 AOI 3 Former ANG Firehouse (Building 12)

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

AOI 3: Former ANG Firehouse. The results in soil and groundwater are presented in Table 6-2

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

6.5.1 AOI 3 Soil Analytical Results

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

Table 6-4 summarize the soil results.

Soil was sampled at the surface (0 to 2 feet bgs), shallow subsurface (8 to 10 feet bgs), and deep 

subsurface (18 to 20 feet bgs) at boring AOI03-01. In surface soil, PFOA, PFHxS, PFNA, PFBS, 

and PFOS were detected at concentrations below their respective SLs: PFOA at 0.348 J μg/kg,

PFOS at 1.97 μg/kg, PFHxS at 0.340 J μg/kg, PFNA at 0.113 J μg/kg, and. PFBS at 0.042 J μg/kg. 
Site Inspection Report

Army Aviation Support Facility #3, Peoria, Illinois

AECOM 6-5

In shallow subsurface soil, PFOS, PFHxS, and PFBS were detected at concentrations below their 

respective SLs, with concentrations ranging from 0.032 J μg/kg to 1.07 J μg/kg. PFOA and PFNA 

were not detected in shallow subsurface soil at AOI 3. PFOS was detected in deep subsurface 

soil at a concentration of 0.232 J μg/kg. PFOA, PFHxS, PFNA, and PFBS were not detected in 

deep subsurface soil.

Soil was also sampled at the surface (0 to 2 feet bgs) and shallow subsurface (5 to 15 feet bgs) 

at downgradient boundary boring locations PEOR-02 and PEOR-03. PFOS in surface soil 

exceeded the SL of 13 μg/kg at PEOR-03, with a concentration of 16.1 μg/kg. PFOS was also 

detected below the SL at PEOR-02, with a concentration of 9.89 μg/kg. PFOA, PFHxS, PFNA, 

and PFBS were detected in surface soil below their respective SLs, with concentrations ranging 

from 0.024 J μg/kg to 1.96 μg/kg. 

PFOA, PFOS, PFHxS, PFNA, and PFBS were all detected below their respective SLs in shallow 

subsurface soil at PEOR-02 and PEOR-03:

• PFOA was detected in two of four samples, with concentrations ranging from 0.109 J 

μg/kg to 0.548 J μg/kg. 

• PFOS and PFHxS were detected in all four samples, with concentrations ranging from 

0.099 J μg/kg to 3.13 μg/kg. 

• PFNA was only detected at PEOR-02, with a concentration of 0.058 J μg/kg. 

• PFBS was detected in three of four samples, with concentrations ranging from 0.025 J 

μg/kg to 0.042 J μg/kg. 

The maximum concentrations for all five analytes detected in the shallow subsurface soil at the 

downgradient boundary locations were observed in the 5 to 7 feet bgs samples collected at 

PEOR-02.

6.5.2 AOI 3 Groundwater Analytical Results

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

summarizes the groundwater results.

Groundwater was sampled from temporary monitoring well AOI03-01. PFOA was detected above 

the SL of 6 ng/L at a concentration of 76.8 ng/L. PFOS was detected above the SL of 4 ng/L at a 

concentration of 15.7 ng/L. PFHxS was detected above the SL of 39 ng/L at a concentration of 

321 J- ng/L. PFBS was detected below the SL of 601 ng/L at a concentration of 49.9 ng/L. PFNA 

was not detected.

Groundwater was also sampled at the downgradient boundary temporary wells PEOR-02 and

PEOR-03. SLs exceedances were as follows: 

• PFOA exceeded the SL of 6 ng/L with concentrations of 69.7 ng/L at PEOR-02 and 

951 ng/L at PEOR-03.

• PFOS exceeded the SL of 4 ng/L with concentrations of 138 ng/L at PEOR-02 and 

44.3 ng/L at PEOR-03.

• PFHxS exceeded the SL of 39 ng/L with concentrations of 419 ng/L at PEOR-02 and 

1,020 ng/L at PEOR-03.

PFNA was detected below the SL of 6 ng/L in one well (PEOR-02) at 4.86 ng/L. PFBS was 

detected below the SL of 601 ng/L in both wells at concentrations of 15.0 ng/L at PEOR-02 and 

200 ng/L at PEOR-03.
Site Inspection Report

Army Aviation Support Facility #3, Peoria, Illinois

AECOM 6-6

6.5.3 AOI 3 Conclusions

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

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

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

in groundwater, further evaluation at AOI 3 is warranted. 

6.6 AOI 4 Former Metal Plating Facility

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

AOI 4: Former Metal Plating Facility. The results in soil and groundwater are presented in Table 

6-2 through Table 6-5. Soil and groundwater results are presented on Figure 6-1 through

Figure 6-7.

6.6.1 AOI 4 Soil Analytical Results

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

6-4 summarize the soil results.

Soil was sampled from surface soil (0 to 2 feet bgs) from boring locations AOI04-01 and AOI04-

02. Soil was also sampled from the shallow subsurface (4 to 6 feet bgs and 9 to 10 feet bgs)

interval at AOI04-01. Soil was also sampled from AOI04-02 at the shallow subsurface (10 to 12

feet bgs) and deep subsurface (18 to 20 feet bgs) intervals.

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

SLs. PFOS was detected at both locations, AOI04-01 and AOI04-02, with concentrations of 0.324

J μg/kg and 0.906 μg/kg, respectively. PFHxS was only detected at AOI04-02 with a concentration 

of 0.166 J μg/kg. PFBS was only detected at AOI04-02, with a concentration of 0.032 J μg/kg.

PFOA and PFNA were not detected in surface soil at AOI 4.

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

below their respective SLs: 

• PFOA was only detected at AOI04-02 with a concentration 0.387 J μg/kg.

• PFOS and PFHxS were detected in all three subsurface soil samples, with

concentrations ranging from 0.183 J μg/kg to 3.28 μg/kg.

• PFBS was detected in two of three samples (both at AOI04-01), with concentrations of

0.028 J μg/kg (4 to 6 feet bgs) and 0.049 J μg/kg (9 to 10 feet bgs).

• PFNA was not detected in shallow subsurface soil at AOI 4.

PFHxS was detected in deep subsurface soil at AOI04-02, with a concentration of 0.054 J μg/kg. 

PFOA, PFOS, PFNA, and PFBS were not detected in deep subsurface soil.

Soil was also sampled from the downgradient facility boundary boring locations PEOR-02 and 

PEOR-03. Data from these borings are described in Section 6.5.1.

6.6.2 AOI 4 Groundwater Analytical Results

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

summarizes the groundwater results. 

Groundwater was sampled from temporary monitoring well locations AOI04-01 and AOI04-02. 

PFOA, PFOS, and PFHxS were detected above their respective SLs. PFOA was detected above 

the SL of 6 ng/L in both temporary well locations, with concentrations of 22.5 ng/L at AOI04-01 
Site Inspection Report

Army Aviation Support Facility #3, Peoria, Illinois

AECOM 6-7

and 50.7 ng/L at AOI04-02. PFOS was detected above the SL of 4 ng/L at both temporary wells, 

with concentrations of 25.6 ng/L at AOI04-01 and 123 ng/L at AOI04-02. PFHxS was detected 

above the SL of 39 ng/L both temporary wells, with concentrations of 264 ng/L at AOI04-01 and 

175 ng/L at AOI04-02. PFBS was detected below the SL of 601 ng/L at both locations, with 

concentrations of 61.5 ng/L at AOI04-01 and 16.6 ng/L at AOI04-02. PFNA was not detected in 

groundwater at AOI 4.

Groundwater was also sampled from the downgradient facility boundary temporary monitoring 

wells PEOR-02 and PEOR-03. Data from these wells are described in Section 6.5.2.

6.6.3 AOI 4 Conclusions

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

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

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

in groundwater, further evaluation at AOI 4 is warranted.
Site Inspection Report

Army Aviation Support Facility #3, Peoria, Illinois

AECOM 6-8

THIS PAGE INTENTIONALLY BLANK
Table 6-2

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

Site Inspection Report, Peoria Army Aviation Support Facility #3

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

PFBS 1900 ND U ND U 0.507 J 0.041 J 0.027 J ND U ND UJ 0.042 J ND U 0.032 J

PFHxS 130 0.697 J 0.722 J 41.2 1.52 0.432 J 0.122 J 0.192 J 0.340 J ND U 0.166 J

PFNA 19 0.672 J 0.574 J 0.265 J 0.456 J 0.153 J 0.060 J ND UJ 0.113 J ND U ND U

PFOA 19 0.335 J 0.290 J 0.529 J 0.265 J 0.249 J ND U ND UJ 0.348 J ND U ND U

PFOS 13 23.6 44.3 J 155 24.0 2.54 1.28 0.118 J 1.97 0.324 J 0.906 J

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AOI Area of Interest

U = The analyte was not detected at a level greater than or equal to the adjusted DL D duplicate

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. DL detection limit

ft feet

HQ hazard quotient

ID identification

LCMSMS liquid chromatography with tandem mass spectrometry

LOD limit of detection

ND analyte not detected above the LOD

OSD Office of the Secretary of Defense

QSM Quality Systems Manual

Qual interpreted qualifier

SB soil boring

USEPA United States Environmental Protection Agency

μg/kg micrograms per kilogram

a. Assistant Secretary of Defense, July 2022. Risk Based Screening Levels Calculated for PFOA, PFOS, PFBS, PFHxS, and PFNA in Groundwater or Soil using 

USEPA’s Regional Screening Level Calculator. HQ=0.1, May 2022. Soil screening levels based on residential scenario for incidental ingestion of contaminated soil.

AOI01 AOI03 AOI04

AOI04-02-SB-0-2

03/23/2022

0-2 ft

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

AOI03-01-SB-0-2-D

03/21/2022

0-2 ft

AOI04-01-SB-0-2

03/23/2022

0-2 ft

AOI02

AOI02-01-SB-0-2

03/23/2022

0-2 ft

AOI03-01-SB-0-2

03/21/2022

0-2 ft

AOI01-04-SB-0-2

03/21/2022

0-2 ft

AOI01-05-SB-0-2

03/21/2022

0-2 ft

AOI01-02-SB-0-2

03/22/2022

0-2 ft

AOI01-03-SB-0-2

03/22/2022

0-2 ft

Area of Interest

Sample ID

Sample Date

Depth

AOI01-01-SB-0-2

03/22/2022

0-2 ft

AECOM 6-9 
Table 6-2

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

Site Inspection Report, Peoria Army Aviation Support Facility #3

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual Result Qual

PFBS 1900 ND U 0.024 J ND U 0.050 J 0.062 J

PFHxS 130 0.181 J 1.96 0.778 J 3.30 4.70

PFNA 19 0.089 J 0.160 J 0.262 J 2.55 3.53

PFOA 19 0.621 J 0.290 J 0.129 J 1.15 J 1.10 J

PFOS 13 0.819 J 9.89 16.1 180 J 342 J

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AOI Area of Interest

U = The analyte was not detected at a level greater than or equal to the adjusted DL D duplicate

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. DL detection limit

ft feet

HQ hazard quotient

ID identification

LCMSMS liquid chromatography with tandem mass spectrometry

LOD limit of detection

ND analyte not detected above the LOD

OSD Office of the Secretary of Defense

QSM Quality Systems Manual

Qual interpreted qualifier

SB soil boring

USEPA United States Environmental Protection Agency

μg/kg micrograms per kilogram

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

a. Assistant Secretary of Defense, July 2022. Risk Based Screening Levels Calculated for PFOA, PFOS, PFBS, PFHxS, and PFNA in Groundwater or Soil using 

USEPA’s Regional Screening Level Calculator. HQ=0.1, May 2022. Soil screening levels based on residential scenario for incidental ingestion of contaminated soil.

Sitewide

PEOR-04-SB-0-2

03/22/2022

0-2 ft

PEOR-04-SB-0-2-D

03/22/2022

0-2 ft

PEOR-02-SB-0-2

03/22/2022

0-2 ft

PEOR-03-SB-0-2

03/22/2022

0-2 ft

Area of Interest

Sample ID

Sample Date

Depth

PEOR-01-SB-0-2

03/22/2022

0-2 ft

AECOM 6-10
Table 6-3

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

Site Inspection Report, Peoria Army Aviation Support Facility #3

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Resu

Soil, LCMSMS compliant with QSM 5.3 Table B-15 (μg/kg)PFBS 25000 ND U ND U ND U ND U 0.612 J 0.080 J ND U 0.032 J 0.028 PFHxS 1600 1.76 0.083 J 1.05 J 0.477 J 19.4 1.69 ND U 1.07 J 0.183 PFNA 250 ND U ND U 1.92 0.242 J 0.120 J ND U ND U ND U ND PFOA 250 0.133 J ND U 1.54 0.109 J 0.241 J 0.123 J ND U ND U ND PFOS 160 ND U 1.10 J 57.6 14.9 60.2 4.76 0.417 J 0.307 J 0.498 

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acidPFOA perfluorooctanoic acidPFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AOI Area of InterestU = The analyte was not detected at a level greater than or equal to the adjusted DL D duplicate

DL detection limitft feetHQ hazard quotientID identificationLCMSMS liquid chromatography with tandem mLOD limit of detectionND analyte not detected above the LODOSD Office of the Secretary of DefenseQSM Quality Systems ManualQual interpreted qualifierSB soil boringUSEPA United States Environmental Protectioμg/kg micrograms per kilogram

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

AOI01 

AOI03

AOI03-01-SB-8-10

03/21/2022

8-10 ft

AOI0

0

AOI01-03-SB-8-10

03/22/2022

8-10 ft

AOI02

AOI02-01-SB-3-5

03/23/2022

3-5 ft

AOI01-02-SB-8-10

03/22/2022

8-10 ft

AOI01-03-SB-4-6

03/22/2022

4-6 ft

AOI01-01-SB-8-10

03/22/2022

8-10 ft

AOI01-02-SB-4-6

03/22/2022

4-6 ft

Area of Interest

Sample ID

Sample Date

Depth

AOI01-01-SB-4-6

03/22/2022

4-6 ft

AECOM 
Table 6-3

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

Site Inspection Report, Peoria Army Aviation Support Facility #3

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Resu

Soil, LCMSMS compliant with QSM 5.3 Table B-15 (μg/kg)PFBS 25000 ND U ND U ND U 0.042 J ND U 0.039 J 0.025 J 0.073 J 0.098 PFHxS 1600 1.10 J 0.330 J 0.496 J 2.31 0.127 J 0.866 J 0.099 J 2.47 3.26 PFNA 250 ND U ND U ND U 0.058 J ND U ND U ND U 0.447 J 0.890 PFOA 250 0.387 J ND U ND U 0.548 J ND U 0.109 J ND U 0.587 J 0.786 PFOS 160 0.967 J 0.113 J 0.193 J 3.13 0.766 J 0.134 J 0.166 J 37.4 J 76.4 

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acidPFOA perfluorooctanoic acidPFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AOI Area of InterestU = The analyte was not detected at a level greater than or equal to the adjusted DL D duplicate

DL detection limitft feetHQ hazard quotientID identificationLCMSMS liquid chromatography with tandem mLOD limit of detectionND analyte not detected above the LODOSD Office of the Secretary of DefenseQSM Quality Systems ManualQual interpreted qualifierSB soil boringUSEPA United States Environmental Protectioμg/kg micrograms per kilogram

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

PEOR

0

PEOR-03-SB-13-15

03/22/2022

13-15 ft

PEOR-04-SB-6-8

03/22/2022

6-8 ft

PEOR-03-SB-6-8

03/22/2022

11-13 ft

03/22/2022

6-8 ft

PEOR-02-SB-5-7

03/22/2022

5-7 ft

PEOR-02-SB-10-12

03/22/2022

10-12 ft

Area of Interest Sitewide

Sample ID

Sample Date

Depth

AOI04

AOI04-02-SB-10-12

03/23/2022

10-12 ft

PEOR-01-SB-5-7

03/22/2022

5-7 ft

PEOR-01-SB-11-13

AECOM 
Table 6-3

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

Site Inspection Report, Peoria Army Aviation Support Facility #3

Analyte OSD Screening 

Level a

Result Qual

Soil, LCMSMS compliant with QSM 5.3 Table B-15 (μg/kg)PFBS 25000 0.139 JPFHxS 1600 5.09 JPFNA 250 0.100 JPFOA 250 1.35 JPFOS 160 19.7

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acidPFOA perfluorooctanoic acidPFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AOI Area of InterestU = The analyte was not detected at a level greater than or equal to the adjusted DL D duplicate

DL detection limitft feetHQ hazard quotientID identificationLCMSMS liquid chromatography with tandem mLOD limit of detectionND analyte not detected above the LODOSD Office of the Secretary of DefenseQSM Quality Systems ManualQual interpreted qualifierSB soil boringUSEPA United States Environmental Protectioμg/kg micrograms per kilogram

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

PEOR-04-SB-13-15-D

03/22/2022

13-15 ft

Area of Interest

Sample ID

Sample Date

Depth

Sitewide

AECOM 
Table 6-4

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

Site Inspection Report, Peoria Army Aviation Support Facility #3

Area of Interest

Sample ID

Sample Date

Depth

Analyte Result Qual Result Qual

PFBS ND U ND UPFHxS ND U 0.054 JPFNA ND U ND UPFOA ND U ND UPFOS 0.232 J ND U

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

PFNA perfluorononanoic acidPFOA perfluorooctanoic acidPFOS perfluorooctanesulfonic acidAcronyms and Abbreviations

AOI Area of InterestDL detection limitft feetID identificationLCMSMS liquid chromatography with tandem mass LOD limit of detectionND analyte not detected above the LODQSM Quality Systems ManualQual interpreted qualifierSB soil boringμg/kg micrograms per kilogram

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

AOI03

AOI03-01-SB-18-20

03/21/2022

18-20 ft

AOI04

AOI04-02-SB-18-20

03/23/2022

18-20 ft

AECOM 
Table 6-5

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

Site Inspection Report, Peoria Army Aviation Support Facility #3

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Resu

PFBS 601 72.2 28.9 210 2.70 J 40.8 49.9 61.5 16.6 10.5

PFHxS 39 341 745 7250 38.2 259 J- 321 J- 264 175 55.1PFNA 6 ND U 44.0 15.6 ND U ND U ND U ND U ND U ND 

PFOA 6 306 116 4770 4.23 62.2 76.8 22.5 50.7 2.89 

PFOS 4 17.8 2180 7560 28.4 12.3 15.7 25.6 123 8.56

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acidPFOA perfluorooctanoic acidPFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AOI Area of InterestJ- = Estimated concentration, biased low D duplicate

U = The analyte was not detected at a level greater than or equal to the adjusted DL GW groundwater

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

Area of Interest

Sample ID

Sample Date

AOI01-01-GW

03/22/2022 03/23/2022

AOI03-01-GW

03/22/2022

AOI01-02-GW

03/22/2022

AOI01-03-GW

03/22/2022

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

AOI01 AOI03 AOI04

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

AOI04-02-GW

03/23/2022

PE

0

AOI03-01-GW-D

03/22/2022

AOI04-01-GW

03/23/2022

AOI02

AOI02-01-GW

AECOM 
Table 6-5

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

Site Inspection Report, Peoria Army Aviation Support Facility #3

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual

PFBS 601 9.97 15.0 200 65.3

PFHxS 39 51.6 419 1020 769PFNA 6 ND U 4.86 ND U 39.4PFOA 6 2.69 J 69.7 951 205

PFOS 4 7.48 138 44.3 3120

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acidPFOA perfluorooctanoic acidPFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AOI Area of InterestJ- = Estimated concentration, biased low D duplicate

U = The analyte was not detected at a level greater than or equal to the adjusted DL GW groundwater

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

PEOR-04-GW

03/22/2022

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

Sitewide

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

PEOR-02-GW

03/23/2022

PEOR-03-GW

03/23/2022

Area of Interest

Sample ID

Sample Date

PEOR-01-GW-D

03/22/2022

AECOM 
PEOR-01

PEOR-02

PEOR-03

PEOR-04

AOI01-01

AOI01-02

AOI01-03

AOI02-01

AOI03-01

AOI04-01

AOI04-02

PEOR-01

PEOR-02

PEOR-03

PEOR-04

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI01-05

AOI02-01

AOI03-01

AOI04-01

AOI04-02

PFOA Results (μg/Kg)

ND

>ND - 19

>19 - 250

>250 - 2,500

>2,500

PEOR-01

PEOR-02

PEOR-03

PEOR-04

AOI01-01

AOI01-02

AOI01-03

AOI03-01

AOI04-01

AOI04-02

Shallow Intermediate Deep

Base Map: Source: Esri, Maxar, Earthstar Geographics, and the GIS User Community ­ Figure 6-1

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection at Peoria AASF, IL

MS

JH

CM

GIS BY

CHK BY

PM

PFOA Detections in Soil

12420 Milestone Center Drive

Germantown, MD 20876

Legend

Facility Boundary

1:3,840

4/7/2023 4/7/2023

4/7/2023

4/7/2023

0 160 320 640

Feet

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

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

AECOM 6-17
PEOR-01

PEOR-02

PEOR-03

PEOR-04

AOI01-01

AOI01-02

AOI01-03

AOI02-01

AOI03-01

AOI04-01

AOI04-02

PEOR-01

PEOR-02

PEOR-03

PEOR-04

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI01-05

AOI02-01

AOI03-01

AOI04-01

AOI04-02

PFOS Results (μg/Kg)

ND>ND - 13>13 - 160>160 - 1,600>1,600

Shallow Intermediate 

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

CLIENTREVISEDSCALEPROJECT

ARNG

Site Inspection at Peoria AASF, IL

MS

JH

CM

GIS BY

CHK BY

PM

Legend

Facility Boundary

1:3,840

9/7/2022 9/7/2022

9/7/2022

9/7/2022

0 160 320 640

Feet

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

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

AECOM 
PEOR-01

PEOR-02

PEOR-03

PEOR-04

AOI01-01

AOI01-02

AOI01-03

AOI02-01

AOI03-01

AOI04-01

AOI04-02

PEOR-01

PEOR-02

PEOR-03

PEOR-04

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI01-05

AOI02-01

AOI03-01

AOI04-01

AOI04-02

PFBS Results (μg/Kg)

ND>ND - 10>10 - 1,900>1,900 - 25,000>25,000

Shallow Intermediate 

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

CLIENTREVISEDSCALEPROJECT

ARNG

Site Inspection at Peoria AASF, IL

MS

JH

CM

GIS BY

CHK BY

PM

Legend

Facility Boundary

1:3,840

9/7/2022 9/7/2022

9/7/2022

9/7/2022

0 160 320 640

Feet

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

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

AECOM 
PEOR-01

PEOR-02

PEOR-03

PEOR-04

AOI01-01

AOI01-02

AOI01-03

AOI02-01

AOI03-01

AOI04-01

AOI04-02

PEOR-01

PEOR-02

PEOR-03

PEOR-04

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI01-05

AOI02-01

AOI03-01

AOI04-01

AOI04-02

PFHxS Results (μg/Kg)

ND>ND - 10>10 - 130>130 - 1,600>1,600

Shallow Intermediate 

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

CLIENTREVISEDSCALEPROJECT

ARNG

Site Inspection at Peoria AASF, IL

MS

JH

CM

GIS BY

CHK BY

PM

Legend

Facility Boundary

1:3,840

9/7/2022 9/7/2022

9/7/2022

9/7/2022

0 160 320 640

Feet

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

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

AECOM 
PEOR-01

PEOR-02

PEOR-03

PEOR-04

AOI01-01

AOI01-02

AOI01-03

AOI02-01

AOI03-01

AOI04-01

AOI04-02

PEOR-01

PEOR-02

PEOR-03

PEOR-04

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI01-05

AOI02-01

AOI03-01

AOI04-01

AOI04-02

PFNA Results (μg/Kg)

ND>ND - 19>19 - 250>250 - 2,500>2,500

Shallow Intermediate 

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

CLIENTREVISEDSCALEPROJECT

ARNG

Site Inspection at Peoria AASF, IL

MS

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Legend

Facility Boundary

1:3,840

9/7/2022 9/7/2022

9/7/2022

9/7/2022

0 160 320 640

Feet

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

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

AECOM 
PEOR-01

PEOR-02

PEOR-03

PEOR-04

AOI01-01

AOI01-02

AOI01-03

AOI02-01

AOI03-01 AOI04-01

AOI04-02

PEOR-01

PEOR-02

PEOR-03

PEOR-04

AOI01-01

AOI01-02

AOI01-03

AOI02-01

AOI03-01 AOI04-01

AOI04-02

PFOA Results (ng/L)

ND

>ND - 6

>6 - 40

>40 - 70

>70

PEOR-01

PEOR-02

PEOR-03

PEOR-04

AOI01-01

AOI01-02

AOI01-03

AOI02-01

AOI03-01 AOI04-01

AOI04-02

Base Map: Source: Esri, Maxar, Earthstar Geographics, and the GIS User Community ­ Figure 6-6

CLIENT

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Site Inspection at Peoria AASF, IL

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PFOA, PFOS, and PFBS Detections in Groundwater

12420 Milestone Center Drive

Germantown, MD 20876

Legend

Facility Boundary

Groundwater Flow Direction 1:3,840

10/13/2022 10/13/2022

10/13/2022

10/13/2022

0 160 320 640

Feet

PFOS Results (ng/L)

ND

>ND - 4

>4 - 40

>40 - 70

>70

PFBS Results (ng/L)

ND

>ND - 100

>100 - 601

>601 - 2,000

>2,000

PFOA PFOS PFBS

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

AECOM 6-22
PEOR-01

PEOR-02

PEOR-03

PEOR-04

AOI01-01

AOI01-02

AOI01-03

AOI02-01

AOI03-01 AOI04-01

AOI04-02

PFHxS Results (ng/L)

ND>ND - 39>39 - 100>100 - 1,000>1,000

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

CLIENTREVISEDSCALEPROJECT

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Site Inspection at Peoria AASF, IL

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Facility BoundaryGroundwater Flow Direction 1:3,840

9/7/2022 9/7/2022

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0 160 320 640

Feet

PFNA Results (ng/L)

ND>ND - 6>6 - 100>100 - 1,000>1,000

PFHxS PFNA

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

AECOM 
Site Inspection Report

Army Aviation Support Facility #3, Peoria, Illinois

AECOM 6-24

THIS PAGE INTENTIONALLY BLANK
Site Inspection Report

Army Aviation Support Facility #3, Peoria, Illinois

AECOM 7-1

7. Exposure Pathways

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

Figure 7-4. Please note that while the CSM discussion assists in determining if a receptor may 

be impacted, the decision to move from SI to RI or interim action is determined based upon 

exceedances of the SLs for the relevant compounds and whether the release is more than likely 

attributable to the DoD. A CSM presents the current understanding of the site conditions with 

respect to known and suspected sources, potential transport mechanisms and migration 

pathways, and potentially exposed human receptors. A human exposure pathway is considered 

potentially complete when the following conditions are present:

1. Contaminant source;

2. Environmental fate and transport;

3. Exposure point;

4. Exposure route; and

5. Potentially exposed populations.

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

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

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

relevant compounds are detected, in which case the CSM figure uses a half-filled circle symbol to 

represent a potentially complete exposure pathway. Additionally, a completely filled circle symbol is 

used to indicate when a potentially complete exposure pathway has detections of relevant 

compounds above the SLs. Areas with an identified potentially complete pathway that have 

detections of the relevant compounds above the SLs may warrant further investigation. Although 

the CSMs indicate whether potentially complete exposure pathways may exist, the 

recommendation for future study in an RI or no action at this time is based on the comparison of 

the SI analytical results for the relevant compounds to the SLs. 

In general, the potential routes of exposure to the relevant compounds are ingestion and 

inhalation. Human exposure via the dermal contact pathway may occur, and current risk practice 

suggests it is an insignificant pathway compared to ingestion; however, exposure data for dermal 

pathways are sparse and continue to be the subject of toxicological study. The receptors 

evaluated are consistent with those listed in USEPA guidance for risk screening (USEPA, 2001). 

Receptors at the facility include site workers (e.g., facility staff and visiting soldiers), construction 

workers, trespassers (although unlikely due to restricted access), residents outside the facility 

boundary, and recreational users outside of the facility boundary. 

7.1 Soil Exposure Pathway 

The SI results in soil were used to determine whether a potentially complete pathway exists 

between the source and potential receptors at AOI 1, AOI 2, AOI 3, and AOI 4 based on the 

aforementioned criteria. 

7.1.1 AOI 1

AOI 1 is where training use of Tri-Max 30TM fire extinguishers occurred sometime between 2000 

and 2002. During one event, one Tri-Max 30TM fire extinguisher was discharged on the ramp area 

between Pad 5 and 6. Runoff from the ramp flows south, into the grassy area immediately 

adjacent to the ramp, and ultimately into a ditch that drains into the stormwater system and to the 

Illinois River. 
Site Inspection Report

Army Aviation Support Facility #3, Peoria, Illinois

AECOM 7-2

PFOS was detected in surface soil above the SL at AOI 1 and the downgradient facility boundary 

location PEOR-04. PFOA, PFHxS, PFNA, and PFBS were also detected in surface soil below 

their respective SLs at AOI 1. Site workers, construction workers, and trespassers could contact 

constituents in surface soil via incidental ingestion and inhalation of dust. Therefore, the surface

soil exposure pathways for site workers, future construction workers, and trespassers are

potentially complete. Additionally, off-facility residents could contact constituents in dust via 

inhalation during construction activities. Consequently, the dust inhalation pathway for future offfacility residents is potentially complete. PFOA, PFOS, PFHxS, PFNA, and PFBS, were detected 

in shallow subsurface soil at concentrations below their respective SLs. Construction workers 

could contact constituents in shallow subsurface soil during future construction activities; 

therefore the shallow subsurface soil pathway for future construction workers is potentially 

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

7.1.2 AOI 2

AOI 2 is where three 6-gallon drums of bulk AFFF concentrate were stored in the POL Building

during the late 1990s. No information was available on the type or concentration of the AFFF 

stored in the drums. During the VSI, the 6-gallon drums of AFFF were not observed at the facility. 

It is unknown if the drums of AFFF were removed from the facility when the Tri-Max 30TM fire 

extinguishers were taken to Camp Lincoln in approximately 2004 or 2005. There are no drains in 

the POL Building; however, there is grass/dirt in the surrounding area.

PFOS, PFHxS, and PFNA were detected in surface soil below their respective SLs at AOI 2. Site 

workers, construction workers, and trespassers could contact constituents in surface soil via 

incidental ingestion and inhalation of dust. Therefore, the surface soil exposure pathways for site 

workers, future construction workers, and trespassers are potentially complete. Additionally, offfacility residents could contact constituents in dust via inhalation during construction activities. 

Consequently, the dust inhalation pathway for future off-facility residents is potentially complete. 

PFOS was detected in shallow subsurface soil below the SL. Construction workers could contact 

constituents in shallow subsurface soil during future construction activities; therefore the shallow 

subsurface soil pathway for future construction workers is potentially complete. Additionally, 

PFOA, PFOS, PFHxS, and PFNA were detected in surface soil and PFOS and PFHxS were 

detected shallow subsurface soil below their respective SLs at the upgradient facility boundary 

location PEOR-01. The CSM for AOI 2 is presented on Figure 7-2. 

7.1.3 AOI 3

AOI 3 is where Building 12 was utilized as a firehouse by the ILANG before the ILANG vacated 

the facility in 1997. ILANG operations at the firehouse are unknown. The ILANG has been located 

on the Peoria International Airport property since 1947. Because AFFF was introduced to the ANG 

in the 1970s, and based on findings of the ILANG SI (Amec Foster Wheeler, 2018) conducted at 

the current ILANG location, it is presumed that AFFF was maintained on firetrucks at the 

Firehouse, and annual nozzle testing was conducted prior to ILANG moving in 1997. A grassy 

area exists on the north side of the building, with pavement or other buildings on the west, south, 

and east sides of the building.

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

their respective SLs at AOI 3. PFOS exceeded the SL in surface soil at the downgradient boundary 

location PEOR-03. Site workers, construction workers, and trespassers could contact 

constituents in surface soil via incidental ingestion and inhalation of dust. Therefore, the surface 

soil exposure pathways for site workers, future construction workers, and trespassers are 

potentially complete. Additionally, off-facility residents could contact constituents in dust via 

inhalation during construction activities. Consequently, the dust inhalation pathway for future offfacility residents is potentially complete. PFOS, PFHxS, and PFBS were detected in shallow 
Site Inspection Report

Army Aviation Support Facility #3, Peoria, Illinois

AECOM 7-3

subsurface soil at concentrations below their respective SLs. Construction workers could contact 

constituents in shallow subsurface soil during future construction activities; therefore the shallow 

subsurface soil pathway for future construction workers is potentially complete. The CSM for AOI 

3 is presented on Figure 7-3.

7.1.4 AOI 4

AOI 4 is where Building 2 was used as a metal plating facility from the 1940s to 1990s. Multiple 

metals, such as chromium, cadmium, and zinc, were used in the plating and electroplating 

process. Plating operations commonly involve PFAS-containing mist suppressants to reduce the 

risk of metal fires. There is no knowledge of any AFFF-related activities at this building, and it is 

possible that PFAS-containing materials were used or stored at some point in Building 2. The 

waste created from the metal plating process was disposed of in the sinks and building drains. It 

is reported that all drains lead to an oil/water separator and ultimately to the Greater Peoria 

sanitary WWTP.

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

SLs. PFOS exceeded the SL in surface soil at the downgradient boundary location PEOR-03. Site 

workers, construction workers, and trespassers could contact constituents in surface soil via 

incidental ingestion and inhalation of dust. Therefore, the surface soil exposure pathways for site 

workers, future construction workers, and trespassers are potentially complete. Additionally, offfacility residents could contact constituents in dust via inhalation during construction activities. 

Consequently, the dust inhalation pathway for future off-facility residents is potentially complete. 

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

below their respective SLs. Construction workers could contact constituents in shallow subsurface 

soil during future construction activities; therefore the shallow subsurface soil pathway for future 

construction workers is potentially complete. The CSM for AOI 4 is presented on Figure 7-4.

7.2 Groundwater Exposure Pathway

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

exists between the source and potential receptors based on the aforementioned criteria. The 

groundwater sampled in the SI was collected from the surficial water table aquifer.

Common to each of the AOIs is the presence of private and public wells within a 4-mile radius of 

the facility. With SL exceedances occurring at all four AOIs, the pathway for exposure to off-facility 

residents via ingestion of groundwater is considered potentially complete. The facility itself obtains 

their water from the City of Bartonville. The Sankoty Sand aquifer that supplies municipal water

to the City of Bartonville is 1.5 miles to the east of the facility. Because the aquifer is side-gradient 

of the facility, the pathway for exposure to site workers via ingestion of groundwater is considered 

incomplete. Unique features of each AOI are presented below.

7.2.1 AOI 1

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

samples collected at AOI 1 and at the downgradient facility boundary location PEOR-04. Depths 

to water measured at AOI 1 in March 2022 during the SI ranged from 6.78 to 8.31 feet bgs. 

Therefore, in addition to the off-facility residents, the ingestion exposure pathway for future 

construction workers is considered potentially complete. The CSM for AOI 1 is presented on 

Figure 7-1.
Site Inspection Report

Army Aviation Support Facility #3, Peoria, Illinois

AECOM 7-4

7.2.2 AOI 2

PFOS was detected in groundwater above the SL at AOI 2. PFOS and PFHxS was detected in 

groundwater above their respective SLs at the upgradient facility boundary location PEOR-01. 

Depth to water measured at AOI 2 in March 2022 during the SI was 2.33 feet bgs. Therefore, in 

addition to the off-facility residents, the ingestion exposure pathway for future construction 

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

7.2.3 AOI 3

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

SLs at AOI 3 and at the two downgradient facility boundary locations, PEOR-02 and PEOR-03. 

Depths to water measured at AOI 3 in March 2022 during the SI was 5.03 feet bgs. Therefore, in 

addition to the off-facility residents, the ingestion exposure pathway for future construction 

workers is considered potentially complete. The CSM for AOI 3 is presented on Figure 7-3. 

7.2.4 AOI 4

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

SLs at AOI 4 and at the two downgradient facility boundary locations, PEOR-02 and PEOR-03. 

Depths to water measured at AOI 4 in March 2022 during the SI was 4.50 to 5.02 feet bgs. 

Therefore, in addition to the off-facility residents, the ingestion exposure pathway for future 

construction workers is considered potentially complete. The CSM for AOI 4 is presented on 

Figure 7-4. 

7.3 Surface Water and Sediment Exposure Pathway

Surface water and sediment samples were not collected during the SI. The SI results in soil and 

groundwater, in combination with knowledge of the fate and transport properties of PFAS, were 

used to determine whether a potentially complete pathway exists between the source and 

potential receptors.

Common to each of the AOIs is the lack of surface water features within the facility boundary. 

Therefore, the surface water and sediment ingestion exposure pathway for site workers, 

construction workers, or trespassers is considered incomplete. Unique features of each AOI are 

presented below.

7.3.1 AOI 1

PFAS are water soluble and can migrate readily from soil to surface water via leaching and runoff. Because PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in soil and groundwater at 

AOI 1, it is possible that those compounds may have migrated from soil and shallow groundwater 

to the nearby streams that feed into the Lamarsh Creek Watershed and the Pekin Lake-Illinois 

River Watershed to the east and southwest of the facility. Due to potential recreational use of the 

nearby streams and rivers, the surface water and sediment ingestion exposure pathway for offfacility residents and recreational users is considered potentially complete.

7.3.2 AOI 2

Because PFOS, PFHxS, and PFNA were detected in soil and PFOA, PFOS, PFHxS, and PFBS

were detected in groundwater at AOI 2, it is possible that those compounds may have migrated 

from soil and groundwater to the nearby streams. Due to potential recreational use of the nearby

streams and rivers, the surface water and sediment ingestion exposure pathway for off-facility 

residents and recreational users is considered potentially complete. 
Site Inspection Report

Army Aviation Support Facility #3, Peoria, Illinois

AECOM 7-5

7.3.3 AOI 3 

Because PFOA, PFHxS, PFNA, PFBS, and PFOS were detected in soil and PFOA, PFOS,

PFHxS, and PFBS were detected in groundwater at AOI 3, it is possible that those compounds 

may have migrated from soil and groundwater to the nearby streams. Due to potential recreational 

use of the nearby streams and rivers, the surface water and sediment ingestion exposure pathway 

for off-facility residents and recreational users is considered potentially complete. 

7.3.4 AOI 4 

Because PFOA, PFOS, PFHxS, and PFBS were detected in soil and PFOA, PFOS, PFHxS, and 

PFBS were detected in groundwater at AOI 4, it is possible that those compounds may have 

migrated from soil and groundwater to the nearby streams. Due to potential recreational use of 

the nearby streams and rivers, the surface water and sediment ingestion exposure pathway for 

off-facility residents and recreational users is considered potentially complete. 
Site Inspection Report

Army Aviation Support Facility #3, Peoria, Illinois

AECOM 7-6

THIS PAGE INTENTIONALLY BLANK
Media

SOURCE PATHWAY RECEPTOR

AOI 1 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 Transportand Migration Media ExposureRoutes

Inhalation of

dust

Ingestion

Ingestion

Ingestion

Ingestion

Human Receptors:

Current/ Future

Flow-Chart Continues

Partial/ Possible Flow

Flow-Chart Stops

Incomplete Pathway

Potentially Complete Pathway

Potentially Complete Pathway

with Exceedance of SL

/ /

Site

Worker

Construction

Worker2 Resident1 Trespasser/Recreational User1

Site

Worker

Construction

Worker2 Resident1

/ / /

/ / / /

/ / / /

/ /

LEGEND

Figure 7-1

Conceptual Site Model, AOI 1

 Peoria AASF #3

Potential

Off-Facility

Source Not

under

Control of

ARNG

Trespasser/

Recreational User1

1. The resident and recreational users refer to offsite receptors.

2. No current active construction at the facility.

Notes:

/

Fire Training and

Mobile Fire

Extinguishers

Discharge

/

/

/

/

AECOM 7-7
Media

SOURCE PATHWAY RECEPTOR

AOI 2 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 Transportand Migration Media ExposureRoutes

Inhalation of

dust

Ingestion

Ingestion

Ingestion

Ingestion

Human Receptors:

Current/ Future

Flow-Chart Continues

Partial/ Possible Flow

Flow-Chart Stops

Incomplete Pathway

Potentially Complete Pathway

Potentially Complete Pathway

with Exceedance of SL

Site

Worker

Construction

Worker2 Resident1 Trespasser/Recreational User1

Site

Worker

Construction

Worker2 Resident1

/

/ / / /

/ / / /

/ /

LEGEND

Figure 7-2

Conceptual Site Model, AOI 2

 Peoria AASF #3

Potential

Off-Facility

Source Not

under

Control of

ARNG

Trespasser/

Recreational User1

1. The resident and recreational users refer to offsite receptors.

2. No current active construction at the facility.

Notes:

/

/ /

/

/

Bulk AFFF

Storage

/

/

/

/

AECOM 7-8
Media

SOURCE PATHWAY RECEPTOR

AOI 3 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 Transportand Migration Media ExposureRoutes

Inhalation of

dust3

Ingestion3

Ingestion

Ingestion

Ingestion

Human Receptors:

Current/ Future

Flow-Chart Continues

Partial/ Possible Flow

Flow-Chart Stops

Incomplete Pathway

Potentially Complete Pathway

Potentially Complete Pathway

with Exceedance of SL

/ /

Site

Worker

Construction

Worker2 Resident1 Trespasser/Recreational User1

Site

Worker

Construction

Worker2 Resident1

/ / /

/ / / /

/ / / /

/ /

LEGEND

Figure 7-3

Conceptual Site Model, AOI 3

 Peoria AASF #3

Potential

Off-Facility

Source Not

under

Control of

ARNG

Trespasser/

Recreational User1

1. The resident and recreational users refer to offsite receptors.

2. No current active construction at the facility.

3. Pathway result conservatively based off

downgradient SL exceedance at PEOR-03.

Notes:

/

Annual Firetruck

Nozzle Testing

/

/ /

/

AECOM 7-9
Media

SOURCE PATHWAY RECEPTOR

AOI 4 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 Transportand Migration Media ExposureRoutes

Inhalation of

dust3

Ingestion3

Ingestion

Ingestion

Ingestion

Human Receptors:

Current/ Future

Flow-Chart Continues

Partial/ Possible Flow

Flow-Chart Stops

Incomplete Pathway

Potentially Complete Pathway

Potentially Complete Pathway

with Exceedance of SL

/ /

Site

Worker

Construction

Worker2 Resident1 Trespasser/Recreational User1

Site

Worker

Construction

Worker2 Resident1

/ / /

/ / / /

/ / / /

/ /

LEGEND

Figure 7-4

Conceptual Site Model, AOI 4

 Peoria AASF #3

Potential

Off-Facility

Source Not

under

Control of

ARNG

Trespasser/

Recreational User1

1. The resident and recreational users refer to offsite receptors.

2. No current active construction at the facility.

3. Pathway result conservatively based off

downgradient SL exceedance at PEOR-03.

Notes:

/

Plating

Operations Using

Mist

Suppressants

/

/

/

/

AECOM 7-10
Site Inspection Report

Army Aviation Support Facility #3, Peoria, Illinois

AECOM 8-1

8. Summary and Outcome

This section summarizes SI activities and findings. The most significant findings are summarized 

in this section and are reproduced directly or abstracted from information contained in this report. 

The outcome provides general and comparative interpretations of the findings relative to the SLs. 

8.1 SI Activities

The SI field activities were conducted from 21 to 23 March 2022 and consisted of utility clearance, 

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

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

QAPP Addendum (AECOM, 2021a).

To fulfill the project DQOs set forth in the approved SI QAPP Addendum (AECOM, 2021a), 

samples were collected and analyzed for a subset of PFAS by LC/MS/MS compliant with QSM 

5.3 Table B-15 as follows:

• Thirty-four (34) soil samples from 13 boring locations;

• Eleven (11) grab groundwater samples from 11 temporary well locations;

• Twenty (20) QA/QC samples.

An SI is conducted when the PA determines an AOI exists based on probable use, storage, and/or 

disposal of PFAS-containing materials. The SI includes multi-media sampling at AOIs to 

determine whether or not a release has occurred. The SI may conclude further investigation is 

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

required. Additionally, the CSMs were refined to assess whether a potentially complete pathway 

exists between the source and potential receptors for potential exposure at the AOIs, which are 

described in Section 7. 

8.2 Outcome 

Based on the results of this SI, further evaluation under CERCLA is warranted in an RI for AOI 1, 

AOI 2, AOI 3, and AOI 4 (see Table 8-1). Based on the CSMs developed and revised in light of 

the SI findings, there is potential for exposure to receptors from AOI 1, AOI 2, AOI 3, and AOI 4

from sources on the facility resulting from historical DoD activities. Sample analytical 

concentrations collected during the SI were compared to the project SLs in soil and groundwater, 

as described in Table 6-1. A summary of the results of the SI data relative to the SLs is as follows:

• At AOI 1 Tri-Max 30TM Former FTA:

• PFOS was detected in surface soil at concentrations above the respective SLs.

PFOS exceed the SL of 13 μg/kg, with a maximum concentration of 342 J μg/kg at

the downgradient location PEOR-04. The detected concentrations of PFOA,

PFHxS, PFNA and PFBS in soil at AOI 1 were below their respective SLs.

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

above their respective SLs. PFOA exceeded the SL of 6 ng/L, with a maximum

concentration of 4,770 ng/L at location AOI01-03. PFHxS exceeded the SL of 39

ng/L, with a maximum concentration of 7,250 ng/L at location AOI01-03. PFNA

exceeded the SL of 6 ng/L, with a maximum concentration of 44 ng/L at AOI01-02.

PFOS exceeded the SL of 4 ng/L, with a maximum concentration of 7,560 ng/L at

AOI01-03. Based on the results of the SI, further evaluation of AOI 1 is warranted

in the RI.
Site Inspection Report

Army Aviation Support Facility #3, Peoria, Illinois

AECOM 8-2

• At AOI 2 Bulk AFFF Storage:

• The detected concentrations of PFOS, PFHxS, and PFNA in soil at AOI 2 were below

their respective SLs. PFOA and PFBS were not detected in soil at AOI 2.

• PFOS was detected in groundwater above the SL of 4 ng/L, with a concentration of

28.4 ng/L. In the upgradient facility boundary location PEOR-01, PFOS and PFHxS

exceeded the SLs, with concentrations of 8.56 ng/L and 55.1 ng/L, respectively.

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

• At AOI 3 Former ANG Firehouse (Building 12):

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

AOI 3 were below their respective SLs. PFOS at downgradient boundary location

PEOR-03 exceeded the surface soil SL of 13 μg/kg, with a concentration of 16.1

μg/kg.

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

their respective SLs. PFOA exceeded the SL of 6 ng/L, with a maximum

concentration of 76.8 ng/L at location AOI03-01. PFOS exceeded the SL of 4

ng/L, with a maximum concentration of 15.7 ng/L at AOI03-01. PFHxS exceeded

the SL of 39 ng/L, with a maximum concentration of 321 J- ng/L at location

AOI03-01. Downgradient boundary well locations also exceeded the SLs for

PFOA, PFOS, and PFHxS. Based on the results of the SI, further evaluation of

AOI 3 is warranted in the RI.

• At AOI 4 Former Metal Plating Facility:

• The detected concentrations of PFOA, PFOS, PFHxS, and PFBS in soil at AOI 4

were below their respective SLs. PFOS at downgradient boundary location

PEOR-03 exceeded the surface soil SL of 13 μg/kg, with a concentration of 16.1

μg/kg.

• PFOA, PFOS, and PFHxS, were detected in groundwater at concentrations

above their respective SLs. PFOA exceeded the SL of 6 ng/L, with a maximum

concentration of 50.7 ng/L at AOI04-02. PFOS exceeded the SL of 4 ng/L, with a

maximum concentration of 123 ng/L at AOI04-02. PFHxS exceeded the SL of 39

ng/L, with a maximum concentration of 264 ng/L at AOI04-01. Downgradient

boundary well locations also exceeded the SLs for PFOA, PFOS, and PFHxS.

Based on the results of the SI, further evaluation of AOI 4 is warranted in the RI.

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

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

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

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

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

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

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

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

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

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AECOM 8-3

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

AOI Potential 

Release Area

Soil – 

Source Area

Groundwater – 

Source Area

Groundwater –

Facility 

Boundary

Future Action

1 Tri-Max 30TM 

FTA Proceed to RI 

2 Bulk AFFF 

Storage Proceed to RI

3

Former ANG 

Firehouse 

(Building 12)

Proceed to RI

4 Former Metal 

Plating Facility Proceed to RI

Legend:

= detected; exceedance of the screening levels

= detected; no exceedance of the screening levels

= not detected
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