FINAL

Site Inspection Report 

Bangor Training Site

Bangor, Maine

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

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

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

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

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

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

3.1 AOI 1 Building 260 (AASF)....................................................................................3-1

3.2 AOI 2 Building 254 (Cold Storage Hangar)............................................................3-1

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

3.3.1 Bangor ANG Base.......................................................................................3-2

3.3.2 Bangor International Airport Fuel Strike Incident..........................................3-3

3.3.3 Former Dow Air Force Base Fire Training Area ...........................................3-3

3.3.4 Wastewater Treatment Plant .......................................................................3-4

3.3.5 Landfills.......................................................................................................3-4

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

6.2 Soil Physicochemical Analyses .............................................................................6-2
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6.3 AOI 1.....................................................................................................................6-2

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

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

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

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

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

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

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

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

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

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

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

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

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

7.2.2 AOI 2...........................................................................................................7-3

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

7.3.1 AOI 1 and AOI 2..........................................................................................7-3

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

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

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

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

Appendix A Data Usability Assessment and Validation Reports

Appendix B Field Documentation

B1. Log of Daily Notice of Field Activities

B2. Sampling Forms

B3. Field Change Request Forms

B4. Survey Data

Appendix C Photographic Log

Appendix D TPP Meeting Minutes

Appendix E Boring Logs

Appendix F Analytical Results

Appendix G Laboratory Reports

Figures

Figure 2-1 Facility Location

Figure 2-2 Facility Topography

Figure 2-3 Groundwater Features

Figure 2-4 Groundwater Elevations, April 2022

Figure 2-5 Surface Water Features

Figure 3-1 Areas of Interest

Figure 5-1 Site Inspection Sample Locations

Figure 6-1 PFOA Detections in Soil

Figure 6-2 PFOS Detections in Soil

Figure 6-3 PFBS Detections in Soil

Figure 6-4 PFHxS Detections in Soil

Figure 6-5 PFNA Detections in Soil

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

Figure 6-7 PFHxS and PFNA Detections in Groundwater

Figure 7-1 Conceptual Site Model, AOI 1

Figure 7-2 Conceptual Site Model, AOI 2

Tables

Table ES-1 Screening Levels (Soil and Groundwater)

Table ES-2 Summary of Site Inspection Findings and Recommendations

Table 5-1 Site Inspection Samples by Medium

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

Elevations

Table 6-1 Screening Levels (Soil and Groundwater)

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

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

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

ABB-ES ABB Environmental Services

AECOM AECOM Technical Services, Inc.

AFFF aqueous film-forming foam

amsl above mean sea level

AOI Area of Interest

ARNG Army National Guard

ASTM American Society for Testing and Materials

bgs below ground surface 

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act 

CoC chain of custody

CSM conceptual site model

DA Department of the Army

DoD Department of Defense

DOT Department of Transportation

DQO data quality objective

DUA data usability assessment

ELAP Environmental Laboratory Accreditation Program

EM Engineer Manual

ERB equipment rinsate blank

FedEx Federal Express

FMS Field Maintenance Shop

FTA fire training area

gpm gallons per minutes

GPS global positioning system

GPRS Ground Penetrating Radar Systems

HDPE high-density polyethylene 

HFPO-DA hexafluoropropylene oxide dimer acid

HSA Hollow Stem Auger

IDW investigation-derived waste

ITRC Interstate Technology Regulatory Council

LC/MS/MS liquid chromatography with tandem mass spectrometry

MEANG Maine Air National Guard

MEARNG Maine Army National Guard

MEDEP Maine Department of Environmental Protection

MIL-SPEC military specification

NELAP National Environmental Laboratory Accreditation Program

ng/L nanograms per liter

OSD Office of the Secretary of Defense
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PA Preliminary Assessment

PFAS per- and polyfluoroalkyl substances

PFBS perfluorobutanesulfonic acid

PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

PID photoionization detector

PQAPP Programmatic UFP-QAPP

PVC polyvinyl chloride

QA quality assurance

QAPP Quality Assurance Project Plan

QC quality control

QSM Quality Systems Manual

RI Remedial Investigation

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

USGS United States Geological Survey

WWTP wastewater treatment plant
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Executive Summary

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

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

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

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

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

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

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

, and perfluorobutanesulfonic acid 

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

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

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

used, stored, disposed, or released historically (see Table ES-2 for AOI locations). The objective 

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

in the PA and determine whether further investigation is warranted, a removal action is required 

to address immediate threats, or no further action is required based on SLs for relevant 

compounds. This SI was completed at the Bangor Training Site in Bangor, Maine and determined 

further evaluation under the Comprehensive Environmental Response, Compensation, and 

Liability Act (CERCLA) is warranted for AOI 1 and AOI 2. The Bangor Training Site will also be 

referred to as the “facility” throughout this document.

The MEARNG Bangor Training Site comprises 213.7 acres and 13 buildings between two 

properties located immediately east and west of the Bangor International Airport, in the city of 

Bangor, Penobscot County, Maine. One property is located to the east of the runway and one is 

located to the west. Both MEARNG properties are owned by the Federal Government and 

licensed to MEARNG.

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

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

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

(RI) for AOI 1 and AOI 2.

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

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

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

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

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

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

Analyteb

Residential

(Soil)

(μg/kg)a 

0-2 feet bgs

Industrial/ Commercial 

Composite Worker

(Soil)

(μg/kg)a 

2-15 feet bgs

Tap Water

(Groundwater)

(ng/L)a

PFOA 19 250 6

PFOS 13 160 4 

PFBS 1,900 25,000 601 

PFHxS 130 1,600 39

PFNA 19 250 6

Notes:

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

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

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

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

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

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

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

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

AOI

Potential 

Release 

Area

Soil –

Potential 

Source Area

Groundwater –

Potential Source 

Area

Groundwater –

Facility 

Boundary

Future Action

1 Building 260 Proceed to RI 

2 Building 254 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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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 Bangor Training 

Site in Bangor, Maine. 

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 the Bangor Training Site (AECOM Technical Services, Inc. [AECOM], 

2020) and identified two Areas of Interest (AOIs) in the eastern property where PFAS-containing 

materials may have been used, stored, disposed, or released historically. The PA did not identify 

any AOIs in the western property, therefore the focus of this report will be on the eastern property. 

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 Maine ARNG (MEARNG) Bangor Training Site comprises 213.7 acres and 13 buildings 

between two properties located immediately adjacent to the Bangor International Airport runway, 

in the City of Bangor, Penobscot County, Maine (MEARNG, 2015) (Figure 2-1). One property is 

located to the east of the runway, and one is located to the west. Both MEARNG properties are 

owned by the Federal Government and licensed to MEARNG. Both the east and west properties 

were evaluated during the PA (AECOM, 2020), but AOIs were only identified in the eastern 

property and are the focus of this SI. 

Prior to the opening of Bangor International Airport in 1931, the area surrounding the airport was 

primarily agricultural property. After the development of the airport, portions of the surrounding 

area were developed as industrial property. In the early 1940s, the Dow Airfield Military Base was 

developed in the area as a military installation, which remained in operation until 1968. From 1968 

to the present day, parcels of land associated with the former Dow Airfield Military Base have 

been developed as commercial properties (Summit Environmental Consultants, Inc., 2011).

The eastern property of the facility is made up of seven parcels and comprises approximately 

51.85 acres of the 213.7 acres. The main operational buildings include Field Maintenance Shop 

(FMS) #3, an Aviation Readiness Center (located between Buildings 260 and 254), and an Army 

Aviation Support Facility (AASF) (Building 260). Ground equipment maintenance occurs at FMS 

#3, and maintenance of helicopters occurs at the AASF. The AASF also serves as the flight 

operations center for the Aviation Companies. There are also several support buildings at the 

facility, including an aircraft hangar (Building 254) used for cold storage, a covered fuel truck 

building that provides secondary containment for refueling vehicles, a Controlled Humidity 

Storage Building used for cold storage, and a concrete block building used as a petroleum, oil, 

and lubricants and hazardous materials storage (Civil Engineering Services [CES], Inc., 2017).

2.2 Facility Environmental Setting

This section presents information obtained from several sources, including the 2011 

Environmental Baseline Study for the MEANRG Parcel 3 on the Bangor Training Site western 

property (Summit Environmental Consultants, Inc., 2011), the 2015 MEARNG Integrated Cultural 

Resources Management Plan Update (MEARNG, 2015), and the 2017 Integrated Contingency 

Plan for the facility (CES, Inc., 2017). The Bangor Training Site lies within the Coastal Province 

of Maine and is characterized by relatively flat terrain. Topographic relief across the region is 

largely influenced by structural features greatly modified by Pleistocene glaciation (Hunt, 1974). 

The facility of the facility is approximately 2 miles west of the confluence of the Kenduskeag 

Stream and Penobscot River. Development of the Dow Airfield Military Base and surrounding area 

modified the ground surface and reduced topographic relief. As a result, elevations at the facility 

range 170 to 240 feet amsl (Amec Foster Wheeler, 2018) (Figure 2-2).

2.2.1 Geology

This section presents information from the 2018 MEANG Final FY16 Phase 1 Regional SI for 

Perfluorinated Compounds at the adjacent Bangor Air National Guard Base (Amec Foster 

Wheeler, 2018). The Bangor Training Site is situated within the folded and faulted, 

metamorphosed, Paleozoic strata of the northeast-trending Kearsarge-Central Maine 

Synclinorium. The oldest known rocks consist of interbedded pelite and sandstone overlain by 

mafic to felsic volcanic rock of Cambrian and Ordovician age. These rocks are unconformably
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overlain by late Ordovician-early Silurian age beds (Vassalboro Formation) of fine- to mediumgrained feldspathic graywacke with layers or lenses of phyllite (Griffin, 1976).

Regional overburden materials include the glacial moraine deposits of the Presumpscot 

Formation, glacial-stream deposits, and till. The Presumpscot Formation consists of silt, clay, and 

sand washed from glacial ice and deposited on the ocean floor during the Late Wisconsinan 

(Pleistocene) glacial stage (Thompson, 1977). The formation can reach up to 125 feet in thickness 

and is locally fossiliferous. Near the facility, the Presumpscot Formation is typified by poorly 

drained, low-permeability clayey silts. Glacial-stream deposits consist of well-sorted sands and 

gravels deposited in layers by meltwater streams and currents during Late Wisconsinan 

deglaciation. The deposits are commonly overlapped or entirely buried by the Presumpscot 

Formation and include glacial features such as kames and kame terraces, deltas, kettles, eskers, 

and outwash plains (Thompson, 1977). The glacial-stream deposits located nearest the facility 

are found along the Kenduskeag Stream. Glacial till is composed of a heterogeneous mixture of 

clay, silt, sand, gravel, cobbles, and boulders deposited directly by glacial ices. One of two 

varieties (basal or ablation) may be present in the area. Basal till is fine-grained, very compact, 

and exhibits low permeability and poor drainage. Ablation till consists of loose, sandy to stony 

material, characterized by moderate permeability and fair to good drainage. Glacial till generally 

overlies bedrock but may overlie or include sand and gravel (Thompson, 1977).

Subsurface soils encountered near the facility during a 1997 MEANG SI (ABB Environmental 

Services [ABB-ES], 1997) at the adjacent MEANG base generally consisted of clay to silty clay, 

silt, silty sand, or sand with trace to some gravel. Loose to moderately dense soils overlying dense 

or very dense materials were encountered and were characterized as typical of the glacial till 

deposits, as described by Thompson (1977), for the Bangor quadrangle. Bedrock was 

encountered between 4 to 16 feet below ground surface (bgs) in some borings. Bedrock in this 

area is likely the Vassalboro Formation, which consists of dark gray phyllite with quartz stringers 

(Figure 2-3). Wet fracture zones were also encountered. A geotechnical investigation completed 

by Summit Geoengineering Services in August 2005 at the adjacent western property 

encountered bedrock at depths ranging from 1.5 inches to 15.5 feet bgs. These depths are 

consistent with observations at the nearby MEANG facility.

During the SI, fine to silty sand was observed as the dominant lithology of the unconsolidated 

sediments below the eastern property. The borings were completed at depths between 6 and 12

feet bgs. Many of the borings, varying percentages of gravel included in the sand packages and 

intermittent layers of cobble stone were encountered. Samples for grain size analyses were 

collected from finer-grained zones in soil borings AOI01-01 and AOI02-03 and analyzed via 

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

soil samples are comprised primarily of silt (60.38 percent [%] to 67.50%) and clay (30.29% to 

31.28%). Bedrock was encountered at AOI 2 at depths ranging from 3 to 12 feet bgs. These 

results and facility observations are consistent with the reported depositional environment of the 

region. Boring logs are presented in Appendix E, and grain size results are presented in 

Appendix F.

2.2.2 Hydrogeology

The facility lies within the lower Penobscot River Basin, which covers an area of approximately 

825 square miles. The largest supplies of groundwater in the basin occur in the unconsolidated 

deposits formed by glaciofluvial processes. Under favorable conditions, as much as 1,000 gallons 

of water per minute (gpm) may be obtained from wells constructed in ice-contact deposits 

(Prescott, 1964).

The nearest sand and gravel aquifers are located over three miles southwest of the facility, at the 

southern end of Hermon Bog (Foster & Smith, 1992). The bedrock formations in the lower 
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Penobscot River Basin are sparsely fractured, and groundwater is generally only present in these 

secondary openings. Hydraulic continuity varies widely depending on the size of the fractures. A 

1964 survey of 613 bedrock wells in the lower Penobscot River Basin found that groundwater 

yields ranged from less than 0.5 to 100 gpm (Prescott, 1964). Drinking water for the facility is 

provided by the Bangor Water District and is sourced from Floods Pond. In addition, an active 

potable well provides water to the Engagement Skills Trainer building. This well has tested positive 

for PFAS and is sampled bi-annually for PFAS, as discussed later in this section.

During a 1997 MEANG SI, depth to groundwater at the adjacent MEANG base was observed at 

depths ranging from 8 to 23 feet bgs (ABB-ES, 1997). The water table appeared to be present in 

the overburden at the southern portion of the MEANG base (closer to the Bangor Training Site) 

and in the bedrock at the northern end of the base. Groundwater levels in MEANG monitoring 

wells ranged from approximately 1 to 15 feet bgs that were 1 to 4 feet higher in the spring. 

Groundwater at the MEANG base flows southeast, towards the Penobscot River; however, local

groundwater flow conditions in the overburden till may be locally influenced (as evidenced by the 

results of the SI) by large structures that extend below the surface and extend across large surface 

areas on the various properties across Bangor International Airport. Average hydraulic 

conductivity values were 4.09 x 10-3 feet per minute for bedrock wells, and 5.0074 x 10-3 feet per 

minute for overburden wells (ABB-ES, 1997).

Depths to water measured in April 2022 during the Bangor Training Site SI ranged from 1.52 to 

6.84 feet bgs. Hydraulic gradient was measured at approximately 0.0012 feet per foot. The 

general topography of the surrounding area would suggest that the groundwater flow direction is 

southeast (similar to the observed groundwater flow at the adjacent MEANG facility); however,

site-specific groundwater flow collected during this SI indicates that groundwater flows west as 

presented on Figure 2-4. Depth to water was observed to be shallow in many of the borings 

drilled across the facility. Additionally, several borings encountered bedrock refusal indicating a 

potential bedrock high underlying the facility. These depth to water measurements and observed 

groundwater flow direction may be influenced by the bedrock surface or other lithologic feature 

beneath the facility. Further sampling and evaluation are required to refine the observed 

groundwater flow direction.

Using data from the Maine Well Database, potable wells were identified within a 4-mile radius of 

the MEARNG property, including domestic, commercial, and municipal water supply wells as 

indicated in Figure 2-3 (Maine Geological Survey, 2020). Five wells are identified as being within 

1-mile and potentially downgradient/cross-gradient of the facility (based on observed groundwater 

flow during the SI). These potable wells are all open bedrock wells with total depths ranging from 

65 to 425 feet bgs. In all five wells, the overburden has been cased off thus preventing hydraulic 

communication between the overburden and bedrock at the well head. Additionally, the MEARNG 

sampled water from a drinking water well supplying the Engagement Skills Trainer building on 16 

May 2017 for 18 PFAS. The well was installed on 3 May 2013 to a total depth of 600 feet bgs. 

The well casing was installed to 30 feet bgs, with bedrock encountered at 18 feet bgs. PFOA and 

PFBS were detected at concentrations of 4.47 nanograms per liter (ng/L) and 2.54 ng/L, 

respectively, and PFOS was not detected. Tabulated results from this sampling event are included 

in the PA report (AECOM, 2020). Due to the 2017 PFAS detections in drinking water, sampling 

for PFAS was mandated by the ARNG. Water from the Engagement Skills Trainer building is 

sampled bi-annually for PFAS. In August 2018, PFOA and PFBS were detected at concentrations 

of 24.7 ng/L and 8.9 ng/L, respectively; PFOS was not detected. Laboratory results from the 

August 2018 sampling event are included in the PA report (AECOM, 2020). In response to these 

results, the MEARNG voluntarily cut-off and capped the drinking water fountains in the building 

supplied by the well on the western property. During the PA, no AOIs were identified in this portion 

of the facility related to ARNG activities, as a result, this area was not evaluated as part of the SI

(see Section 1).
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2.2.3 Hydrology

No surface water features are present on the MEARNG Bangor Training Site eastern property. 

The “Domestic Channel”, which is a channelized portion of Birch Stream, abuts the property to 

the west-northwest and is the nearest surface waterbody. According to Maine Department of 

Environmental Protection (MEDEP), Birch Stream and Shaw Brook are considered "urban 

impaired streams" for which the City of Bangor has a Watershed Management Plan. Storm water 

runoff from the facility flows into storm drains located on the property and in the vicinity and drain 

to the Domestic Channel. The Domestic Channel/Birch Stream drains into the Kenduskeag 

Stream (CES, Inc., 2017), which is located approximately 1 mile northeast of the facility. Surface 

water features are presented on Figure 2-5.

2.2.4 Climate

Bangor is located less than 50 miles from the Atlantic Ocean and within 30 miles of Penobscot 

Bay. The climate of Bangor is categorized as humid continental, with cold, snowy winters and 

warm summers. The weather in Bangor is influenced by air masses that originate from several 

general regions. Continental air masses originating in the North America polar region consist of 

dry, cool air. Warm maritime air masses can originate either from the subtropical Atlantic Ocean 

or Gulf of Mexico, and cold maritime air masses can originate from the sub-polar regions of the 

North Atlantic. Air masses that flow into Maine often originate in the prevailing westerlies (Amec 

Foster Wheeler, 2018).

The average temperature ranges from 21.8 degrees Fahrenheit (°F) in the winter to 67.1°F in the 

summer, with an annual average temperature of 45°F. Bangor receives an average annual 

precipitation in rainfall of 41.71 inches and an average annual precipitation in snowfall of 74.6

inches (National Oceanic and Atmospheric Administration, 2022). Rainfall is distributed evenly

throughout the year, with the wettest month being November and the driest month being January. 

Snowfall generally occurs in November to April, with most snowfall occurring between December 

and March.

2.2.5 Current and Future Land Use

The MEARNG Bangor Training Site is used for the maintenance of rotary wing aircrafts and 

ground vehicles. Activities carried out at the facility include administrative and financial services, 

training of personnel, warehousing of supplies and equipment, building maintenance and repair, 

and vehicle maintenance and repair.

Land use around the Bangor Training Site is consistent with the City of Bangor Zoning for Airport 

Development District. The facility is located within the Bangor International Airport complex, which 

is surrounded by mixed land use that includes commercial/industrial and business enterprise 

parks, a mobile home park and cemetery to the southwest, University College to the northeast, 

and Bangor Municipal Golf Course to the southeast. The MEANG Air Base and Bangor 

International Airport terminal and parking areas bound the eastern property to the northwest.

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 birds, fish, plants, insect, and mammals are federally endangered, threatened, 

proposed, and/ or are listed as candidate species in Penobscot County, Maine (United States Fish 

and Wildlife Service [USFWS], 2022).
Site Inspection Report

Bangor Training Site, Bangor Maine

AECOM 2-5

• Birds: Rufa Red Knot, Calidris canutus rufa (threatened)

• Fishes: Atlantic Salmon, Salmo salar (endangered)

• Flowering Plants: Eastern Prairie Fringed Orchid, Platanthera leucophaea

(threatened)

• Insects: Monarch butterfly, Danaus plexippus (special concern)

• Mammals: Northern Long-eared Bat, Myotis septentrionalis (threatened), Little Brown 

Bat, Myotis Lucifugus (threatened), Tricolored Bat, Perimyotis subflavus (threatened), 

Canada Lynx, Lynx canadensis (threatened)

2.3 History of PFAS Use

AOI 1 is the Building 260 (AASF) complex. This complex includes the hangars and flight 

operations office space within the complex. AFFF releases at the AOI include a 2003 fire 

suppression system AFFF release contained to building drainage lines that have since been 

replaced, a 2011 fire suppression system AFFF release to the fire suppression pump room and 

city sanitary sewer lines, a 2016 fire suppression system AFFF release to the fire suppression 

pump room, ramp area outside the pump room, and runoff sump, and most recently, a 2023 fire

suppression system AFFF release from the fire suppression pump room to the tarmac 

immediately outside the pump room. 

AOI 2 is Building 254 (Cold Storage Hangar). The potential PFAS release at AOI 2 involved the 

fire suppression system release of 300 gallons of Ansul Jet-X 2% High Expansion Foam 

concentrate; it is unknown whether Ansul Jet-X 2% High Expansion Foam concentrate contained

PFAS. The test was confined by the hangar walls, and the dried foam was eventually 

containerized and disposed of as municipal trash. If foam escaped during the release via floor 

drains, it would have entered into the municipal sanitary system.

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

groundwater flow directions. A description of each AOI is presented in Section 3.
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Facility Location

Legend

Facility Boundary

Bangor ANG Facility Boundary

^_

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Bangor Training Site - 

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Figure 2-2

Facility Topography

Legend

Facility Boundary

Bangor ANG Facility Boundary

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Facility Boundary

Groundwater Elevation Contour

Inferred Groundwater Elevation Contour

Groundwater Flow Direction

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Figure 2-3

Groundwater Elevations,

April 2022

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Bangor Training Site -

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Legend

Facility Boundary

Bangor ANG Facility

Boundary

Water Body

Wetland

River/Stream

Canal/Ditch

Inferred Groundwater Flow

Direction

Groundwater Flow Direction

Geology

Devonian to Ordovician

sandstone and limestone

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slate and schist

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metasedimentary rock

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Figure 2-4

Groundwater Features

0 0.75 1.5 3

Miles

Bangor Training Site - 

Western Property Bangor Training Site - 

Eastern Property

Birch Stream

Domestic Channel

AECOM 2-10
Hermon Bog

Osgood Brook

Bir ch

Stre am

Kenduskeag Stream

Shaw Brook

Lower Kenduskeag

Stream Watershed

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River Watershed

Domestic Channel

Legend

Facility Boundary

Bangor ANG Facility Boundary

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Surface Water Flow Direction

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Figure 2-5

Surface Water Features

0 1,400 2,800 5,600

Feet

Bangor Training Site -

 Eastern Property

Bangor Training Site - 

Western Property

AECOM 2-11
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AECOM 3-1

3. Summary of Areas of Interest 

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

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

identified at the eastern property of the Bangor Training Site and grouped into two AOIs (AECOM, 

2020). The PA did not identify any AOIs at the western property. The potential release areas are 

shown on Figure 3-1.

3.1 AOI 1 Building 260 (AASF)

AOI 1 is the Building 260 (AASF) complex. This complex includes the hangars and flight 

operations office space within the complex. The AASF has a fire suppression system comprised 

of two 1,200-gallon AFFF tanks: one tank contains National Foam Centurion 3% AFFF 

concentrate, the other contains Buckeye BFC-3.1 Platinum 3% AFFF concentrate. The deluge 

fire suppression system was installed in 2003 during the construction of new hangar space and 

is the only AFFF fire suppression system on the MEARNG property. During the installation of the 

fire suppression system, a small quantity of AFFF concentrate was released from the tanks to 

pipes within the building. The exact quantity of AFFF released is unknown, but it did not migrate 

further than the building confines.

A second release occurred in 2011 when a gasket malfunction resulted in approximately 1,200 

gallons of Buckeye BFC-3.1 Platinum 3% AFFF concentrate being released. The AFFF released 

drained into the fire suppression room floor drains and into the sanitary sewer system. All the 

AFFF not recovered in the fire suppression room eventually travelled to the City of Bangor 

treatment plant.

Another accidental release occurred in 2016 when the AFFF tanks triggered an incorrectly 

identified solenoid. Approximately 30 gallons of AFFF spilled across the ramp outside the fire 

suppression room and into a sump designed for capturing runoff. The AFFF was captured and 

contained within the ramp and sump area; it was subsequently vacuumed out of the sump in a 

control manner.

More recently, a release occurred on 10 January 2023. An air compressor on the fire suppression 

system failed and caused the dry valve to trip, activating the fire pumps and charging the line. The 

pressure drop allowed National Foam Centurion C6 AFFF 3% foam mix to be released to the 

tarmac outside the fire suppression room. In total, approximately 100 gallons (30 gallons of 3% 

foam and impacted snow, 70 gallons of foam-water mixture) was recovered.

In addition to the releases from the fire suppression systems, MEARNG confirmed that AFFF TriMaxTM fire extinguishers were previously stored on the parking areas at the AASF. Testing and 

maintenance of these fire extinguishers was performed off-facility.

Building 260 (AASF) is surrounded by pavement. According to MEARNG staff, AFFF releases at 

AOI 1 have been contained to the AASF interior, interior drains leading to sanitary system pipes, 

and the ramp area and sump outside the fire suppression room. No significant pavement cracks 

were observed during the visual SI; therefore, the presence of pavement at the AOI likely inhibited 

subsurface migration. However, it is possible that any released AFFF may have infiltrated the 

subsurface via joints between areas that are paved with different materials. 

3.2 AOI 2 Building 254 (Cold Storage Hangar)

AOI 2 is an aircraft hangar currently used for the cold storage of rotary wing aircraft. The building 

was historically used for aviation maintenance, but was transitioned to cold storage in the 1980s.It 
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Bangor Training Site, Bangor Maine

AECOM 3-2

contains a fire suppression system, including a 300-gallon tank containing Ansul Jet-X 2% High 

Expansion Foam (HEF). The fire suppression system was tested once between 2013-2018 and 

involved a full release of the 300-gallon HEF tank. The HEF was complete enclosed inside the 

building, allowed to dry, collected, and containerized.

3.3 Adjacent Sources

Several adjacent sources were identified during the PA. These include the Bangor ANG Base, 

Bangor International Airport fuel strike, Former Dow AFB Fire Training Area, City of Bangor 

Wastewater Treatment Plant, and Pine Tree Landfill. The potential release areas are shown on 

Figure 3-1.

3.3.1 Bangor ANG Base

The Bangor ANG Base is located at the Bangor International Airport, approximately 0.5 miles 

northwest of the facility. The ANG Base encompasses approximately 314 acres of land leased 

from the city of Bangor and the Dow Air Force Base. The MEANG has conducted a PA (BB&E, 

Inc., 2015) and an SI (Amec Foster Wheeler, 2018) for PFAS at the Bangor ANG Base. Twelve

(12) potential release areas at the MEANG facility were identified in the PA, but three (Buildings

515, 415, and 493) were recommended for no further action. The remaining nine were subject of 

a Site Inspection. A list of the nine potential release areas is listed below with pertinent findings 

summarized as reported in the 2018 SI (updated screening values have not been applied in this 

report). The results presented below are available in the Phase 1 SI Report (Amec Foster 

Wheeler, 2018).

• Building 542 – Soil samples indicated that five of the six relevant PFAS compounds 

were detected in two of the four soil samples collected, but no samples exceeded 

applicable screening criteria. 

• Building 496 – Soil samples indicated that five of six relevant PFAS compounds were 

detected in one of six soil samples collected. The one detection did not exceed 

applicable screening criteria. Groundwater was collected from one temporary 

monitoring well. All six relevant PFAS compounds were detected and PFOA and PFOS 

exceeded the applicable screening criteria.

• Fire Department Current Nozzle Testing Location (East of Building 542) – Soil samples 

indicated that all six relevant PFAS compounds were detected in two of the six soil 

samples collected, but no samples exceeded applicable screening criteria. 

Groundwater was collected from one temporary monitoring well. All six relevant PFAS 

compounds were detected and PFOA and PFOS exceeded the applicable screening 

criteria.

• Fire Department Current Nozzle Testing Location (East End of Taxiway C) – Soil 

samples indicated that all six relevant PFAS compounds were detected in four of the 

six soil samples collected, but no samples exceeded applicable screening criteria. 

Groundwater was collected from one temporary monitoring well. All six relevant PFAS 

compounds were detected and PFOA and PFOS exceeded the applicable screening 

criteria.

• Fire Department Historic Nozzle Testing Location – Soil samples indicated that five of 

the six relevant PFAS compounds were detected in one of the six soil samples 

collected, but no samples exceeded applicable screening criteria. Groundwater was 

collected from one temporary monitoring well. Five of the six relevant PFAS compounds 

were detected and PFOA and PFOS exceeded the applicable screening criteria.
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AECOM 3-3

• Dry Detention Basin – Soil samples indicated that all six relevant PFAS compounds 

were detected in one or more of the six soil samples collected, but no samples 

exceeded applicable screening criteria. Groundwater was collected from one temporary 

monitoring well. All six relevant PFAS compounds were detected and PFOA and PFOS 

exceeded the applicable screening criteria.

• Building 512 – Soil samples indicated that all six relevant PFAS compounds were 

detected in two of the six soil samples collected, but no samples exceeded applicable 

screening criteria. Groundwater was collected from one temporary monitoring well. All 

six relevant PFAS compounds were detected and PFOA and PFOS exceeded the 

applicable screening criteria.

• Former Fire Department – Soil samples indicated that five of the six relevant PFAS 

compounds were detected in one of the six soil samples collected, but no samples 

exceeded applicable screening criteria. Groundwater was collected from one temporary 

monitoring well. All six relevant PFAS compounds were detected and PFOA and PFOS 

exceeded the applicable screening criteria.

• Dry Detention Pond – Soil samples indicated that all six relevant PFAS compounds 

were detected in one of the four soil samples collected, but no samples exceeded 

applicable screening criteria. Groundwater was collected from one temporary 

monitoring well. All six relevant PFAS compounds were detected and PFOA and PFOS 

exceeded the applicable screening criteria.

3.3.2 Bangor International Airport Fuel Strike Incident

A release of AFFF occurred in recent years within the Bangor International Airport property, on 

the tarmac area near the southwestern corner of the facility. During construction activities, a fuel 

line was struck, causing a fuel release to the paved surface. The MEANG fire department 

responded to the incident by spraying AFFF across the fuel spill area to prevent a fire. The exact 

date of the incident as well as the volume and type of AFFF released are unknown. The area 

MEANG staff described where the incident occurred as a paved surface between the MEARNG 

property and the Bangor International Airport, south of the Domestic Channel. It is possible AFFF 

released to this area may have infiltrated the subsurface soil via cracks in the pavement, the 

grassy areas north and south of the incident, and the Domestic Channel.

3.3.3 Former Dow Air Force Base Fire Training Area

The former Dow AFB Fire Training Area (FTA) exists off-facility, west of the Bangor International 

Airport runway. According to the 2011 Environmental Baseline Survey for the MEARNG Bangor 

Training Site, the former Dow AFB FTA was used by the Air Force, the National Guard, and the 

city of Bangor for fire training from 1947 to 1984. During training, flammable liquids (including JP4 fuel, cleaning solvents, hydraulic fluids, paint thinners and motor oil) and solid wastes (including 

fuel filters and tires) were burned or deposited at various pits within the FTA (Summit 

Environmental Consultants, Inc., 2011). MEANG fire department staff stated during interviews 

that the former FTA was used by the Air Force and city of Bangor for fire training. According to the 

MEANG 2015 PA, the FTA was located on property transferred from the Dow AFB to the MEANG, 

but it is unclear whether the MEANG ever used the FTA for training (BB&E, Inc., 2015). The 

property has since been relinquished by the MEANG. A Notice of Potential Liability from the 

MEDEP dated 17 October 2017 identifies the US Air Force, the MEANG, and city of Bangor as 

responsible parties under Maine’s Uncontrolled Hazardous Substance Sites law and CERCLA.

An SI was performed by MEDEP in 2019 to determine the extent of fuel, solvents, and PFAS 

contamination as a result of historic activities at the FTA. Six shallow subsurface soil samples 

were collected from borings; no surface soil samples were collected. Only two PFAS compounds 
Site Inspection Report

Bangor Training Site, Bangor Maine

AECOM 3-4

were detected in soil and did not exceed applicable screening criteria. Five groundwater samples 

were collected from two existing wells and three new monitoring wells. PFAS was detected in all 

five monitoring wells and exceeded applicable screening criteria (PFOA and/or PFOS) in three 

locations.

3.3.4 Wastewater Treatment Plant

There is no wastewater treatment plant (WWTP) at the facility; however, the city of Bangor WWTP 

is located approximately 2.3 miles southeast of the facility. The Bangor Training Site sanitary 

sewer system feeds into the city of Bangor sanitary sewer system which conveys wastewater to 

the city of Bangor WWTP. The treated water is then released into the Penobscot River. Solids 

removed from the waste stream are dewatered and composted for reuse at a private composting 

facility. Because onsite releases of AFFF at the MEARNG facility have resulted in AFFF entering 

the city sanitary sewer system, the city of Bangor WWTP is considered an adjacent source of 

potential PFAS release to the environment.

3.3.5 Landfills

There are no landfills on the facility. The nearest landfill that receives municipal waste from the 

city of Bangor is the Pine Tree Landfill, located in Hampden, ME, approximately 2.8 miles 

southwest of the facility.

Landfills are not usually a primary potential release area of PFAS, but materials disposed of in 

landfills may create a secondary source of contamination. Such materials, to name a few, may 

include sludge from a WWTP that processes PFAS-laden water, used AFFF storage containers, 

or products associated with waterproofing uniforms or boots. At the Bangor Training Site, high 

expansion foam released as part of a Building 254 fire suppression system test was collected and 

disposed of as municipal waste.
­ Figure 3-1

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection at Bangor Training Site, ME

10/17/2022

10/17/2022

10/17/2022

MS

JD

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, USGS, Intermap, INCREMENT P, NRCan,

Esri Japan, METI, Esri China (Hong Kong), Esri Korea, Esri (Thailand), NGCC, (c)

10/17/2022

1:142,779

Areas of Interest

12420 Milestone Center Drive

Germantown, MD 20876

!P

!P

!P

&<

Former DOW

AFB FTA

Fuel Line

Strike Incident

Building 260

(AASF)

MEANG Former

Fire Department

MEANG Fire Department

(Building 512)

MEANG Fire Department Historic

Nozzle Testing Location

MEANG Dry

Detention Pond

MEANG Dry

Detention Basin

MEANG Building 542 (Fuel

Cell Repair Hangar)

MEANG Fire Department Current Nozzle

testing Location (East of Building 542)

MEANG Fire Department Current Nozzle

testing Location (East of Taxiway C)

MEANG Building

515 (Flight Line)

MEANG Building 496

(Former Main Hangar)

MEANG Building

493 (Base Supply)

MEANG Building 415 (Central

Accumulation Point)

Building 254

(Hangar)

Shaw

Brook

Birch Stream

Lower Kenduskeag

Stream Watershed

Lower Souadabscook

Stream Watershed

Felts

Brook-Penobscot

River Watershed

Domestic

Channel

AOI 1

AOI 2

Area of Interest

Potential Release Area

Facility Boundary

Bangor ANG Facility Boundary

Water Body

Wetland

River/Stream

Canal/Ditch

Surface Water Flow Direction

Inferred Groundwater Flow Direction

Groundwater Flow Direction

!P Commercial Well

!P Domestic Well

&<

Water Supply Well

Lower Souadabscook

Stream Watershed

Souadabscook Stream

Sh aw

Brook

Pine Tree

Landfill

!P

Felts

Brook-Penobscot

River Watershed

Penobscot River

City of

Bangor WWTP

1

2

3 Shaw

B

or ok

Pug

Brook

W h eele r St ream

Penobscot River

KenduskeagS tream

Lower Kenduskeag

Stream

Watershed

Lower Souadabscook

Stream Watershed Felts Brook-Penobscot

River Watershed

1

2

3

0 500 1,000 2,000

Feet

Bangor Training Site -

 Eastern Property

Bangor Training Site - 

Western Property

AECOM 3-5
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AECOM 3-6

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AECOM 4-1

4. Project Data Quality Objectives

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

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

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

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

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

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

AOIs.

4.1 Problem Statement

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

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

SLs are presented in Section 6.1 of this report.

4.2 Information Inputs

Primary information inputs included:

• The PA for Bangor Training Site (AECOM, 2020);

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

accordance with the site-specific Uniform Federal Policy (UFP)-QAPP Addendum

(AECOM, 2021); and

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

parameters measured at the time of sampling.

4.3 Study Boundaries

The scope of the SI is horizontally bounded by the property limits of the Bangor Training Site

(Figure 2-2). Off-facility sampling is not included in the scope of this SI; however, if future offfacility sampling is required, the proper stakeholders will be notified, and necessary rights of entry 

will be obtained by ARNG with the property owner(s). The scope of the SI is vertically bounded 

as follows: groundwater (12 feet bgs), subsurface soil from hollow stem auger (HSA) borings (up 

to 12 feet bgs), and surface soil (0 to 2 feet bgs). The temporal boundaries of the study are limited 

by seasonal conditions (late-fall and winter can be hampered by cold temperatures and snow).

4.4 Analytical Approach

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

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

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

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

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

4.5 Data Usability Assessment

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

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

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

methods, the assessment determines whether project execution and the resulting data have met 
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AECOM 4-2

installation specific DQOs. Both sampling and analytical activities are considered to assess

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

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

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

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

requirements of the SI QAPP Addendum (AECOM, 2021).
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Bangor Training Site, Bangor Maine

AECOM 5-1

5. Site Inspection Activities

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

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

in accordance with the following approved documents:

• Final 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, Bangor Training Site dated January 2020 

(AECOM, 2020);

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

Addendum, Bangor Training Site, Bangor, Maine dated December 2021 (AECOM, 

2021); and

• Final Site Safety and Health Plan, Bangor Training Site, Bangor, Maine dated April

2022 (AECOM, 2022).

The SI field activities were conducted from 19 to 29 April 2022 and consisted of utility clearance,

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

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

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

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

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

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

• Seventeen (17) soil samples from six boring locations;

• Six grab groundwater samples from six temporary wells; 

• Twelve (12) quality assurance (QA)/quality control (QC) samples.

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

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

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

in Appendix B1. Sampling forms are provided in Appendix B2, Field Change Request Forms

are provided in Appendix B3, land survey data 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 10 February 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, MEARNG, USACE, MEDEP and representatives 

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

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

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

the SI QAPP Addendum (AECOM, 2021).

A TPP Meeting 3 was held [date to be determine] after the field event to discuss the results of the 

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

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

warranted.

5.1.2 Utility Clearance

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

north 811 “Call Before You Dig” Maine utility clearance provider to notify them of intrusive work on 

19 April 2022. Additionally, AECOM contracted Ground Penetrating Radar Systems (GPRS), a 

private utility location service, to perform utility clearance. GPRS performed utility clearance of 

the proposed boring locations on 19 April 2022 with input from the AECOM field team and facility 

staff. General locating services and ground-penetrating radar were used to complete the 

clearance. Additionally, the first 5 feet of each boring were pre-cleared using a hand auger to 

verify utility clearance in shallow subsurface where utilities would typically be encountered.

5.1.3 Source Water and Sampling Equipment Acceptability

A potable water source collected from an outdoor spigot on Building 250 was sampled on 14 May

2021 and again on 21 April 2022 to assess usability for decontamination of drilling equipment. 

Results of the samples (BTS-DECON-01 and BTS-DECON-02) confirmed this source to be 

acceptable for use in this investigation; therefore, it was used throughout the field activities.

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

results of the decontamination water sample associated with the Building 250 are provided in 

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

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

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

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

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

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

regarding the allowable materials within the sampling environment.

5.2 Soil Borings and Soil Sampling

Soil samples were collected using a GeoProbe® 7822 drill rig via HSA/split-spoon tooling to collect 

soil cores to the target depth in accordance with the SI QAPP Addendum (AECOM, 2021). A hand 

auger was used to collect soil from the top 5 feet of the boring, in accordance with AECOM utility 

clearance procedures. The soil boring locations are shown on Figure 5-1, and depths are 

provided Table 5-1.

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

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

AECOM 5-3

approximately 2 feet above the groundwater table, and one subsurface soil sample at the midpoint between the surface and the groundwater table. Given the conditions at the facility, this was 

not accomplished at every boring. See Section 5.8 for further details on deviations from the SI 

QAPP and Table 5-1 for a list of the soil samples collected. 

Split-spoons were collected every 5 feet and logged for lithological descriptions by a field geologist 

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

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

Observations and measurements were recorded on field 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. Photographs of 

the boring cores were also taken and are shown in Appendix C.

Soil borings completed during the SI indicate that the dominant lithology underlying the Bangor 

Training Site consists of fine silty sand and lean clay. Intermittent layers of gravelly sand and 

cobble stone were also found throughout the eastern property. The borings were completed at 

depths between 6 and 12 feet bgs. These observations are consistent with the understood 

depositional environment of the region. It should be noted that oily soils and petroleum odors were 

observed in boring AOI02-04. PID readings from the boring ranged from 2 to 2,889 parts per 

million with the highest readings measured in the 9-11 feet bgs interval. Several oil-in-soil test kits 

were used to determine the presence or absence of petroleum impacts. The test kits were positive 

for oil at the 4-5 feet bgs interval, but negative for the 5-7, 7-9, and 9-11 feet bgs intervals. A thin 

film of oil (0.07 inches) was measured sitting on top of the water table. 

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

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

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

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

carbon (TOC) (USEPA Method 9060A), pH (USEPA Method 9045D), and grain size (ASTM 

Method D-422) in accordance with the SI QAPP Addendum (AECOM, 2021).

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

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

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

equipment was used, such as a hand auger for the shallow soil samples, equipment rinsate blanks

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.

Borings advanced in asphalt were abandoned by backfilling with bentonite chips to approximately 

6 inches bgs, and the remainder of the borehole were patched with an asphalt cold patch. 

Similarly, borings advanced into concrete were abandoned by backfilling with bentonite chips to 

approximately 6 inches bgs, and the remainder of the borehole was filled with concrete to provide 

as flush a surface as possible. HSA borings were converted to temporary wells, which were 

subsequently abandoned in accordance with the SI QAPP Addendum (AECOM, 2021) using 

bentonite chips at completion of sampling activities.

5.3 Temporary Well Installation and Groundwater Grab Sampling

Temporary wells were installed using a GeoProbe® 7822 drill rig. Once the borehole was 

advanced to the desired depth, a temporary well was constructed of a 5-foot section of 1-inch 

Schedule 40 poly-vinyl chloride (PVC) screen with sufficient casing to reach ground surface. New 

PVC pipe and screen were used to avoid cross contamination between locations (no filter pack, 

bentonite seal, cement, or pad was installed. The screen intervals for the temporary wells are 
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Bangor Training Site, Bangor Maine

AECOM 5-4

provided in Table 5-2. As noted in Section 5.8 below, six of seven planned temporary wells were 

installed.

Groundwater samples were collected after a period 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. The 

temporary wells were purged at a rate determined in the field to reduce turbidity and draw down 

prior to sampling. Water quality parameters (e.g., temperature, specific conductance, pH, 

dissolved oxygen, and oxidation-reduction potential) were measured using a water quality meter 

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

Additionally, a subsample of each groundwater sample was collected in a separate container, and 

a shaker test was completed to identify if there were any foaming. No foaming was noted in any 

of the groundwater samples.

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

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

standard CoC procedures to the laboratory and analyzed by LC/MS/MS compliant with QSM 5.3

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

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

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

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

equipment was used, such as a hand auger for the shallow soil samples, equipment rinsate blanks

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

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

6 °C during shipment.

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

in accordance with the SI QAPP Addendum (AECOM, 2021) by removing the stickup component 

and PVC and backfilling the hole with bentonite chips to approximately 6 inches bgs. 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 29 April 2022. Groundwater elevation 

measurements were collected from the six 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 is provided in Table 5-2.

5.5 Surveying

The northern side of each well casing was surveyed by Nadeau Surveying a licensed land 

surveyor in the state of Maine, following guidelines provided in the SOPs provided in the SI QAPP 

Addendum (AECOM, 2021). Survey data from the newly installed wells on the facility were 

collected on 29 April 2022 the applicable Universal Transverse Mercator zone projection with 

North American Datum 1983 State Plane (horizontal) and North American Vertical Datum 1988 

(vertical). The surveyed well data are provided in Appendix B4.

5.6 Investigation-Derived Waste

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

the SI is considered non-hazardous waste and was managed in accordance with the SI QAPP 
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Bangor Training Site, Bangor Maine

AECOM 5-5

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

2018). ARNG coordinated waste profiling, transportation, and disposal of the solid IDW.

Soil IDW (i.e., soil cuttings) generated during the SI activities were contained in labeled, 55-gallon 

Department of Transportation (DOT)-approved steel drums and left onsite in a designated waste 

storage area. The soil IDW was not sampled and assumes the characteristics of the associated 

soil samples collected from that source location. 

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

decontamination fluids) were contained in labeled, 55-gallon DOT-approved steel drums, and left 

onsite in a designated waste storage area. The liquid IDW was not sampled and assumes the 

characteristics of the associated groundwater samples collected from that source location. 

Containerized liquid IDW will be managed and disposed of by ARNG under a separate contract.

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, pH by USEPA Method 9045D, and 

Grain Size by ASTM Method D422.

5.8 Deviations from SI QAPP Addendum

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

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

(Appendix B3): 

• Due to bedrock refusal at approximately 3 feet bgs, only surficial soil was collected from 

boring AOI02-01. 

• At location AOI02-03, groundwater was encountered less than one foot from ground 

surface, likely due to a clay layer. The hole was hand-cleared to 6 feet bgs, and a 5 feet 

screen was installed at the bottom of the cleared hole to serve as a temporary well. No 

augers or rig was used to drill deeper.

• On 20 April 2022, in an attempt to clear through asphalt at location AOI02-02, approximately 

1.25 feet of asphalt was encountered followed by approximately 1.25 feet of concrete. This 

total depth of asphalt and concrete clearing was the total extent of the drill rig’s capabilities,

and work was stopped.

• AECOM, USACE, and ARNG decided the lacking information from AOI02-02 and AOI02-

01 may result in a data gap. AECOM remobilized to the site on 29 April 2022 with the private 

utility locator contractor and scanned several additional locations north of AOI02-01.

AECOM’s driller hand cleared a new location (AOI02-04) and was able to drill to bedrock 

refusal at approximately 12 feet bgs. AECOM communicated the findings to USACE and 

ARNG and all parties agreed that three soil samples and a water sample should be collected 

from this location. Soil and groundwater sample specifications from location AOI02-04 are 

described in Table 5-1 and Table 5-2.
AECOM 5-6

Site Inspection Report

Bangor Training Site, Bangor Maine

THIS PAGE INTENTIONALLY BLANK 
Table 5-1

Site Inspection Samples by Medium

Site Inspection Report, Bangor Training Site, Bangor, Maine

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)Grain Size (ASTM D-422)

Comments

AOI01-01-SB-00-02 4/21/2022 9:30 0-2 x

AOI01-01-SB-03-04 4/21/2022 10:00 3-4 x

AOI01-01-SB-5.3-5.8 4/21/2022 12:10 5.3-5.8 x

AOI01-02-SB-00-02 4/21/2022 13:45 0-2 x

AOI01-02-SB-02-03 4/21/2022 14:10 2-3 x

AOI01-03-SB-00-02 4/20/2022 14:30 0-2 x

AOI01-03-SB-05-07 4/20/2022 14:50 5-7 x x x

AOI01-03-SB-11-12 4/20/2022 15:45 11-12 x

AOI01-04-SB-00-02 4/21/2022 16:30 0-2 x

AOI01-04-SB-05-06 4/21/2022 16:45 5-6 x

AOI02-01-SB-00-02 4/20/2022 8:45 0-2 x

AOI02-03-SB-00-02 4/19/2022 12:00 0-2 x

AOI02-03-SB-2.5-3.0 4/21/2022 12:00 2.5-3 x

AOI02-03-SB-05-06 4/19/2022 15:00 5-6 x x x

AOI02-04-SB-00-02 4/29/2022 11:10 0-2 x

AOI02-04-SB-04-05 4/29/2022 11:20 4-5 x

AOI02-04-SB-05-07 4/29/2022 11:30 5-7 x

AOI01-03-SB-11-12-D 4/20/2022 16:00 11-12 x Duplicate

AOI01-02-SB-00-02-D 4/21/2022 14:00 0-2 x Duplicate

AOI01-03-SB-00-02-MS 4/20/2022 14:30 0-2 x MS

AOI01-03-SB-00-02-MSD 4/20/2022 14:30 0-2 x MSD

AOI01-03-SB-05-07-D 4/20/2022 15:00 5-7 x x Duplicate

AOI01-03-SB-05-07-MS 4/20/2022 14:50 5-7 x x MS

AOI01-03-SB-05-07-MSD 4/20/2022 14:50 5-7 x x MSD

AOI01-01-GW 4/25/2022 12:30 N/A x

AOI01-02-GW 4/25/2022 14:10 N/A x

AOI01-02-GW-MS 4/25/2022 14:10 N/A x MS

AOI01-02-GW-MSD 4/25/2022 14:10 N/A x MSD

AOI01-03-GW 4/25/2022 10:30 N/A x

AOI01-04-GW 4/25/2022 15:30 N/A x

AOI02-03-GW 4/25/2022 16:45 N/A x

AOI02-03-GW-D 4/25/2022 16:45 N/A x Duplicate

AOI02-04-GW 4/29/2022 15:30 N/A x

Soil Samples

Groundwater Samples

AECOM 5-7
Table 5-1

Site Inspection Samples by Medium

Site Inspection Report, Bangor Training Site, Bangor, Maine

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)Grain Size (ASTM D-422)

Comments

BTS-ERB-01 4/20/2022 19:05 N/A x ERB

BTS-ERB-02 4/20/2022 19:10 N/A x ERB

BTS-FRB-01 4/21/2022 12:00 N/A x FRB

BTS-DECON-01 5/14/2021 11:10 N/A x DECON

BTS-DECON-02 4/21/2022 11:00 N/A x DECON

Notes:

ASTM = American Society for Testing and Materials

bgs = below ground surface

ERB = equipment rinsate blank

FD = field duplicate

FRB = field reagent blank

LC/MS/MS = Liquid Chromatography Mass Spectrometry

MS/MSD = matrix spike/ matrix spike duplicate

QSM = Quality Systems Manual

TOC = total organic carbon

USEPA = United States Environmental Protection Agency

Quality Control Samples

AECOM 5-8
Table 5-2

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

Site Inspection Report, Bangor Training Site, Bangor, Maine

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 9.5 4.5 - 9.5 145.17 145.00 4.56 4.39 140.61

AOI01-02 9 4 - 9 144.28 143.94 3.73 3.39 140.55

AOI01-03 11.8 6.8 - 11.8 146.95 147.13 5.41 5.59 141.54

AOI01-04 7 2 - 7 148.78 147.15 3.59 1.96 145.19

AOI02-03 6 1 - 6 153.45 151.85 3.12 1.52 150.33

AOI02-04 12 7 - 12 151.14 148.75 9.23 6.84 141.91

Notes:

1

 Temporary well screen set above total depth to capture groundwater interface

bgs = below ground surface

btoc = below top of casing

NA = not applicable

NAVD88 = North American Vertical Datum 1988

2

1

AECOM 5-9
AECOM 

Site Inspection ReportBangor Training Site, Bangor Maine

THIS PAGE INTENTIONALLY BLANK 
?!

?!

?!

?!

"S

?!

?!

?!

Bangor AVRC

GP Storage

Installation

Building 262

Building 256

Butler Building

Building 251

Building 255

Building 250

Conex

POL/Hazmat storage Domestic Channel

AOI 1

AOI 2

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI02-01

AOI02-03

AOI02-04

AOI02-02

Legend

?! Soil Boring/Temporary Monitoring Well

"S Surface Soil Sample

Area of Interest

Facility Boundary

Canal/Ditch

Groundwater Flow Direction

­12420 Milestone Center Drive

Germantown, MD 20876

CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

JD

10/17/2022

10/17/2022

PROJECT Site Inspection at Bangor Training Site, ME

10/17/2022

1:4,800

PM CM 10/17/2022 Base Map: Source: Esri, Maxar, Earthstar Geographics,

and the GIS User Community

Figure 5-1

Site Investigation

Sample Locations

0 200 400 800

Feet

Bangor Training Site -

 Eastern Property

AECOM 5-11
AECOM 5-12 

Site Inspection Report

Bangor Training Site, Bangor Maine

THIS PAGE INTENTIONALLY BLANK 
Site Inspection Report

Bangor Training Site, Bangor Maine

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 and

Section 6.4. Table 6-2 through Table 6-4 present results in soil or groundwater for the relevant 

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

are provided in Appendix G. 

6.1 Screening Levels 

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

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

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

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

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

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

6-1 below.

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

Analyteb

Residential

(Soil)

(μg/kg)a 

0-2 feet bgs

Industrial/ 

Commercial 

Composite 

Worker

(Soil)

(μg/kg)a 

2-15 feet bgs

Tap Water

(Groundwater)

(ng/L)a

PFOA 19 250 6 

PFOS 13 160 4 

PFBS 1,900 25,000 601 

PFHxS 130 1,600 39

PFNA 19 250 6 

Notes:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Bangor Training Site, Bangor Maine

AECOM 6-2

6.2 Soil Physicochemical Analyses

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

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

the results of the TOC, pH, and grain size sampling. The grain size results indicate that the soil is

comprised primarily of silt (60.38 % to 67.50%) and clay (30.29% to 31.28%)

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

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

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

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

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

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

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

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

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

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

6.3 AOI 1

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

AOI 1: Building 260. The soil and groundwater results are summarized on Table 6-2 through 

Table 6-4. 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 and Table 6-3

summarize the soil results.

Ten (10) soil samples were collected from four locations, AOI01-01 through AOI01-04. Surficial 

soil samples were collected from 0 to 2 feet bgs, and shallow subsurface soil samples were taken 

from intervals between 2 to 12 feet bgs at all locations. No deep subsurface soil samples were 

collected from this AOI. PFOA, PFOS, PFHxS, and PFNA were detected in soil, but at 

concentrations below their SLs. PFBS was not detected in any of the soil samples collected at 

AOI 1.

In the surface soil samples, the maximum concentration detected for any relevant compound was 

1.21 micrograms per kilogram (μg/kg) at AOI01-02. In the shallow subsurface, the maximum 

concentration detected for any relevant compound was 1.64 J μg/kg at AOI01-03. 

6.3.2 AOI 1 Groundwater Analytical Results

Figure 6-6 and Figure 6-7 present the ranges of detections in groundwater. Table 6-4

summarizes the groundwater results.

Groundwater was sampled from temporary monitoring wells AOI01-01 through AOI01-04. The 

following exceedances of the SLs were measured:

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

concentration of 3,210 ng/L at AOI01-03. 

• PFOS was detected above the SL of 4 ng/L at all four wells, with a maximum 

concentration of 75.2 ng/L at AOI01-01. 
Site Inspection Report

Bangor Training Site, Bangor Maine

AECOM 6-3

• PFNA was detected above the SL of 6 ng/L at two of the four wells, with a maximum 

concentration of 94.5 ng/L at AOI01-3.

PFHxS and PFBS were detected below their respective SLs in all four AOI 1 wells. 

6.3.3 AOI 1 Conclusions

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

below their respective SLs. PFOA, PFOS, and PFNA were detected in groundwater at 

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

further evaluation at AOI 1 is warranted.

6.4 AOI 2

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

AOI 2: Building 254 (Cold Storage Hangar). The results in soil and groundwater are summarized 

on Table 6-2 through Table 6-4. 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 detections in soil. Table 6-2 and Table 6-3

summarize the soil results.

Soil was sampled from surface soil (0 to 2 feet bgs) and shallow subsurface soil (4 to 7 feet bgs)

from boring locations AOI02-01, AOI02-03, and AOI02-04. No deep subsurface soil samples were 

collected from this AOI. PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in soil, but at 

concentrations below their SLs.

In surface soil, the maximum concentration detected for any relevant compound was 1.83 J μg/kg

at AOI02-01. PFHxS was not detected in surface soil. In the shallow subsurface soil, the maximum 

concentration detected for any relevant compound was 0.138 J μg/kg at AOI02-04. PFOA, PFNA, 

and PFBS were not detected in the shallow subsurface. 

6.4.2 AOI 2 Groundwater Analytical Results

Figure 6-6 and Figure 6-7 present the ranges of detections in groundwater. Table 6-4 

summarizes the groundwater results.

Groundwater was sampled from temporary monitoring wells AOI02-03 and AOI02-04. The 

following exceedances of the SLs were measured:

• PFOA was detected above the SL of 6 ng/L in one well (AOI02-04) with a maximum

concentration of 15.7 ng/L at AOI02-04.

• PFOS was detected above the SL of 4 ng/L in both wells, with a maximum concentration 

of 14.8 ng/L at AOI02-04. 

• PFHxS was detected above the SL of 6 ng/L at one well (AOI02-04) with a maximum 

concentration of 89 ng/L at AOI02-04.

PFNA and PFBS were detected in all four wells below their respective SLs. 
Site Inspection Report

Bangor Training Site, Bangor Maine

AECOM 6-4

6.4.3 AOI 2 Conclusions

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

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

their SLs. Based on the exceedances of the SLs in groundwater, further evaluation at AOI 2 is 

warranted.
Table 6-2

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

Site Inspection Report, Bangor Training Site

Analyte OSD Screening 

Level a

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

PFBS 1900 ND U ND U ND U ND U ND U 0.039 J ND U ND PFHxS 130 ND U 0.163 J 0.156 J ND U ND U ND U ND U ND PFNA 19 0.037 J 0.148 J 0.137 J 0.073 J 0.057 J 1.14 0.033 J 0.316 PFOA 19 ND U 0.132 J 0.131 J 0.195 J 0.081 J 0.953 J ND U 0.268 PFOS 13 0.358 J 1.21 1.09 0.149 J 0.282 J 1.83 0.224 J 0.883 

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobuta

References PFHxS perfluorohex

PFNA perfluorononPFOA perfluorooctaPFOS perfluoroocta

Interpreted Qualifiers Acronyms and Abbreviations

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

D duplicate

Notes DL detection lim

ND = Analyte not detected above the LOD. LOD values are presented in Appendix F. ft feet

HQ hazard quotiID identificationLCMSMS liquid chromLOD limit of detecND analyte not dOSD Office of the QSM Quality SysteQual interpreted qSB soil boringUSEPA United Stateμg/kg micrograms 

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

AOI01 AOI02

AOI02-0

04/2

0

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

AOI02-01-SB-00-02

04/20/2022

0-2 ft

AOI02-03-SB-00-02

04/19/2022

0-2 ft

AOI01-03-SB-00-02

04/20/2022

0-2 ft

AOI01-04-SB-00-02

04/21/2022

0-2 ft

AOI01-02-SB-00-02

04/21/2022

0-2 ft

AOI01-02-SB-00-02-D

04/21/2022

0-2 ft

Area of Interest

Sample ID

Sample Date

Depth

AOI01-01-SB-00-02

04/21/2022

0-2 ft

AECOM 
Table 6-3

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

Site Inspection Report, Bangor Training Site

Analyte OSD Screening 

Level a

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

PFBS 25000 ND U ND U ND U ND U ND U ND U ND U

PFHxS 1600 ND U 0.047 J ND U ND U ND U ND U ND U

PFNA 250 0.023 J ND U ND U 0.065 J 0.065 J ND U ND U

PFOA 250 ND U ND U 0.314 J 1.54 1.64 ND U ND U

PFOS 160 1.07 0.359 J ND U ND U ND U ND U ND U

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS

References PFHxS

PFNA

PFOA

PFOS

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AASF

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

D

DL

ft

HQ

ID

LCMSMS

LOD

ND

OSD

QSM

Qual

SB

USEPA

μg/kg

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 industrial/commercial composite worker scenario for 

incidental ingestion of contaminated soil.

AOI01

AOI01-04-SB-05-06

04/21/2022

5-6 ft

AOI02

AOI02-03-SB-05-06

04/19/2022

5-6 ft

AOI01-03-SB-11-12

04/20/2022

11-12 ft

AOI01-03-SB-11-12-D

04/20/2022

11-12 ft

AOI01-02-SB-02-03

04/21/2022

2-3 ft

AOI01-03-SB-05-07

04/20/2022

5-7 ft

Area of Interest

Sample ID

Sample Date

Depth

AOI01-01-SB-03-04

04/21/2022

3-4 ft

AECOM 6-6
Table 6-3

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

Site Inspection Report, Bangor Training Site

Analyte OSD Screening 

Level a

Result Qual Result Qual

PFBS 25000 ND U ND U

PFHxS 1600 0.109 J 0.056 J

PFNA 250 ND U ND U

PFOA 250 ND U ND U

PFOS 160 0.138 J 0.062 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 AASF Army Aviation Support Facility

U = The analyte was not detected at a level greater than or equal to the adjusted DL AOI Area of Interest

D duplicate

Notes DL detection limit

ND = Analyte not detected above the LOD. LOD values are presented in Appendix F. 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 industrial/commercial composite worker scenario for incidental ingestion of 

contaminated soil.

AOI02

AOI02-04-SB-05-07

04/29/2022

5-7 ft

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

Area of Interest

Sample ID

Sample Date

Depth

AOI02-04-SB-04-05

04/29/2022

4-5 ft

AECOM 6-7
Table 6-4

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

Site Inspection Report, Bangor Training Site

Analyte OSD Screening 

Level a

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

PFBS 601 1.66 J 3.04 J 5.19 0.648 J ND U ND U 6.13

PFHxS 39 21.8 31.2 34.5 5.26 3.25 J 3.46 J 89.0

PFNA 6 2.13 J 9.97 94.5 2.82 J 1.78 J 1.72 J 1.13 JPFOA 6 4.91 39.2 3210 13.2 3.93 J 4.17 15.7

PFOS 4 75.2 57.7 24.1 21.2 14.2 14.6 14.8

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobuta

References PFHxS perfluorohex

PFNA perfluorononPFOA perfluorooctaPFOS perfluoroocta

Interpreted Qualifiers Acronyms and Abbreviations

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

D duplicate

Notes DL detection limND = Analyte not detected above the LOD. LOD values are presented in Appendix F. GW groundwater

HQ hazard quotiID identificationLCMSMS liquid chromLOD limit of detecND analyte not dOSD Office of the QSM Quality SysteQual interpreted qUSEPA United Stateng/l nanogram pe

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

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

AOI01 AOI02

AOI02-03-GW-D

04/25/2022

AOI02-04-GW

04/29/2022

AOI01-04-GW

04/25/2022

AOI02-03-GW

04/25/2022

AOI01-02-GW

04/25/2022

AOI01-03-GW

04/25/2022

Area of Interest

Sample ID

Sample Date

AOI01-01-GW

04/25/2022

AECOM 
Domestic Channel

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI02-03

AOI02-04

Domestic Channel

AOI01-03

AOI02-04

Domestic Channel

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI02-01

AOI02-03

AOI02-04

Shallow Intermediate Deep

­ Figure 6-1

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection at Bangor Training Site, ME

12/14/2022

12/14/2022

12/14/2022

MS

JD

CM

GIS BY

CHK BY

PM

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

12/14/2022

1:4,800

Legend

Facility Boundary

Canal/Ditch

PFOA Detections in Soil

12420 Milestone Center Drive

Germantown, MD 20876

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

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

PFOA Results (μg/Kg)

ND

>ND - 19

>19 - 250

>250 - 2,500

>2,500

0 200 400 800

Feet

AECOM 6-9
Domestic Channel

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI02-03

AOI02-04

Domestic Channel

AOI01-03

AOI02-04

Domestic Channel

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI02-01

AOI02-03

AOI02-04

Shallow Intermediate Deep

Figure 6-2

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection at Bangor Training Site, ME

12/14/2022

12/14/2022

12/14/2022

MS

JD

CM

GIS BY

CHK BY

PM

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

PFOS Detections in Soil

12420 Milestone Center Drive

Germantown, MD 20876

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

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

PFOS Results (μg/Kg)

ND

>ND - 13

>13 - 160

>160 - 1,600

>1,600

12/14/2022

1:4,800 ­ Legend

Facility Boundary

Canal/Ditch

0 200 400 800

Feet

AECOM 6-10
Domestic Channel

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI02-03

AOI02-04

Domestic Channel

AOI01-03

AOI02-04

Domestic Channel

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI02-01

AOI02-03

AOI02-04

Shallow Intermediate Deep

Figure 6-3

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection at Bangor Training Site, ME

12/14/2022

12/14/2022

12/14/2022

MS

JD

CM

GIS BY

CHK BY

PM

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

12/14/2022

PFBS Detections in Soil

12420 Milestone Center Drive

Germantown, MD 20876

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

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

PFBS Results (μg/Kg)

ND

>ND - 10

>10 - 1,900

>1,900 - 25,000

>25,000

1:4,800 ­ Legend

Facility Boundary

Canal/Ditch

0 200 400 800

Feet

AECOM 6-11
Domestic Channel

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI02-03

AOI02-04

Domestic Channel

AOI01-03

AOI02-04

Domestic Channel

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI02-01

AOI02-03

AOI02-04

Shallow Intermediate Deep

Figure 6-4

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection at Bangor Training Site, ME

12/14/2022

12/14/2022

12/14/2022

MS

JD

CM

GIS BY

CHK BY

PM

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

12/14/2022

1:4,800

PFHxS Detections in Soil

12420 Milestone Center Drive

Germantown, MD 20876

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

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

PFHxS Results (μg/Kg)

ND

>ND - 10

>10 - 130

>130 - 1,600

>1,600

­ Legend

Facility Boundary

Canal/Ditch

0 200 400 800

Feet

AECOM 6-12
Domestic Channel

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI02-03

AOI02-04

Domestic Channel

AOI01-03

AOI02-04

Domestic Channel

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI02-01

AOI02-03

AOI02-04

Shallow Intermediate Deep

Figure 6-5

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection at Bangor Training Site, ME

12/14/2022

12/14/2022

12/14/2022

MS

JD

CM

GIS BY

CHK BY

PM

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

12/14/2022

1:4,800

PFNA Detections in Soil

12420 Milestone Center Drive

Germantown, MD 20876

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

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

PFNA Results (μg/Kg)

ND

>ND - 19

>19 - 250

>250 - 2,500

>2,500

0 200 400 800

Feet ­ Legend

Facility Boundary

Canal/Ditch

AECOM 6-13
Domestic Channel

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI02-03

AOI02-04

Domestic Channel

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI02-03

AOI02-04

Domestic Channel

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI02-03

AOI02-04

PFOA PFOS PFBS

Figure 6-6

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection at Bangor Training Site, ME

12/14/2022

12/14/2022

12/14/2022

MS

JD

CM

GIS BY

CHK BY

PM

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

12/14/2022

1:4,800

PFOA, PFOS, and PFBS Detections in Groundwater

12420 Milestone Center Drive

Germantown, MD 20876

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

PFOA Results (ng/L)

ND

>ND - 19

>19 - 250

>250 - 2,500

>2,500

PFOS Results (ng/L)

ND

>ND - 4

>4 - 40

>40 - 70

>70

Legend

Facility Boundary

Canal/Ditch

Groundwater Flow Direction

0 200 400 800

Feet ­

PFBS Results (ng/L)

ND

>ND - 100

>100 - 601

>601 - 2,000

>2,000

AECOM 6-14
Domestic Channel

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI02-03

AOI02-04

Domestic Channel

AOI01-01

AOI01-02

AOI01-03

AOI01-04

AOI02-03

AOI02-04

PFHxS PFNA

Figure 6-7

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection at Bangor Training Site, ME

12/14/2022

12/14/2022

12/14/2022

MS

JD

CM

GIS BY

CHK BY

PM

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

12/14/2022

PFHxS and PFNA Detections in Groundwater

12420 Milestone Center Drive

Germantown, MD 20876

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

0 200 400 800

Feet

PFHxS Results (ng/L)

ND

>ND - 39

>39 - 100

>100 - 1,000

>1,000

1:4,800 ­ Legend

Facility Boundary

Canal/Ditch

Groundwater Flow Direction

PFNA Results (ng/L)

ND

>ND - 6

>6 - 100

>100 - 1,000

>1,000

AECOM 6-15
Site Inspection Report

Bangor Training Site, Bangor Maine

AECOM 6-16

THIS PAGE INTENTIONALLY BLANK
Site Inspection Report

Bangor Training Site, Bangor Maine

AECOM 7-1

7. Exposure Pathways

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

Figure 7-2. Please note that while the CSM discussion assists in determining if a receptor may 

be impacted, the decision to move from SI to RI or interim action is determined based upon 

exceedances of the SLs for the relevant compounds and whether the release is more than likely 

attributable to the DoD. A CSM presents the current understanding of the site conditions with 

respect to known and suspected potential 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 (potential) 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, 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 potential source and potential receptors at AOI 1 and AOI 2 based on the 

aforementioned criteria.

7.1.1 AOI 1

AOI 1 is the Building 260 (AASF) complex, where multiple AFFF releases occurred from the 

hangar fire suppression system. These released include: a 2003 fire suppression system AFFF 

release contained to building drainage lines that have since been replaced, a 2011 fire 

suppression system AFFF release to the fire suppression pump room and city sanitary sewer 

lines, a 2016 fire suppression system AFFF release to the fire suppression pump room, ramp area 
Site Inspection Report

Bangor Training Site, Bangor Maine

AECOM 7-2

outside the pump room, and runoff sump, and a 2023 release which impacted the tarmac 

immediately outside the fire suppression room. Additionally, portable Tri-MaxTM fire extinguishers 

were stored on the parking areas at the AASF.

PFOA, PFOS, PFHxS, and PFNA were detected in surface soil at AOI 1 below their respective 

SLs. Site workers and construction workers could contact constituents in surface soil via incidental 

ingestion and inhalation of dust. Therefore, the surface soil exposure pathway for site workers 

and future construction workers are potentially complete. PFOA, PFOS, PFHxS, and PFNA were 

detected in the shallow subsurface soil at AOI 1. No construction projects were underway at the 

time of the SI fieldwork; therefore, the subsurface soil exposure pathway for future construction 

workers is potentially complete. Due to the restricted entry access at the facility and the 

surrounding land use, the exposure pathway for surface soil and subsurface soil via inhalation 

and ingestion are incomplete for off-facility residents and trespasser/recreational users. The CSM

for AOI 1 is presented on Figure 7-1. 

7.1.2 AOI 2

AOI 2 is Building 254, 300-gallons of Ansul Jet-X 2% High Expansion Foam Concentrate was 

released from a fire suppression system. It is unknown whether Ansul Jet-X 2% High Expansion 

Foam Concentrate contains PFAS. The test was confined by the hangar walls, and the dried foam 

was eventually containerized and disposed of as municipal trash. If foam escaped during the 

release via floor drains, it would have entered into the municipal sanitary system.

PFOA, PFOS, PFBS and PFNA were detected in surface soil at AOI 2 below their respective SLs. 

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

ingestion and inhalation of dust. Therefore, the surface soil exposure pathway for site workers 

and future construction workers are potentially complete. No construction projects were underway 

at the time of the SI fieldwork; therefore, the subsurface soil exposure pathway for future 

construction workers is potentially complete. Due to the restrictive nature of the facility and the 

surrounding land use, the exposure pathway for surface soil and subsurface soil via inhalation 

and ingestion are incomplete for off-facility residents and trespasser/recreational users. The CSM

for AOI 2 is presented on Figure 7-2. 

7.2 Groundwater Exposure Pathway

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

exists between the potential source and potential receptors based on the aforementioned criteria.

7.2.1 AOI 1

PFOA, PFOS, and PFNA were detected above their SLs in groundwater samples collected at AOI 

1. Potable water for the facility is provided by the Bangor Water District and is sourced from Floods 

Pond approximately 15 miles away. Additionally, one potable well associated with the 

Engagement Skills Trainer building exists and has detected concentrations of PFAS. The well is 

cross-gradient (using the facility-specific groundwater contours) of the releases at the facility and

is an open bedrock well approximately 600 feet deep. Therefore, it is unlikely the detections 

observed in the well are related to releases at the facility and could be attributed to other adjacent 

sources. Regardless, MEARNG capped and closed the drinking water fountains connected to this 

well following an SL exceedance of PFOA in 2018. Given this information, the pathway for 

exposure to site workers via ingestion of groundwater is considered incomplete. Off-facility, there 

are five potable wells within 1-mile of the facility. According to the Maine Geological Survey, these 

wells are open bedrock boreholes and range in depths from 65-425 feet bgs. Additionally, none 

of these wells are immediately downgradient of the facility (using the facility-specific groundwater 

contours). Given the degree of uncertainty in the groundwater flow direction on and surrounding 
Site Inspection Report

Bangor Training Site, Bangor Maine

AECOM 7-3

the facility, as well as the uncertainty in hydraulic communication between the overburden and 

bedrock aquifers, conservatively the pathway for exposure to off-facility residents via ingestion of 

groundwater is considered potentially complete with an exceedance of the SL. Finally, depths to 

water measured at AOI 1 in April 2022 during the SI ranged from 1.96 to 5.59 feet bgs. Therefore,

the ingestion exposure pathway for future construction workers is considered potentially complete

with exceedances of the SLs. The CSM for AOI 1 is presented on Figure 7-1. 

7.2.2 AOI 2

PFOA, PFOS, and PFHxS were detected at concentrations above their respective SLs in 

groundwater samples collected at AOI 2. Potable water for the facility is provided by the Bangor 

Water District and is sourced from Floods Pond approximately 15 miles away. Additionally, one 

potable well associated with the Engagement Skills Trainer building exists and has detected 

concentrations of PFAS. The well is cross-gradient (using the facility-specific groundwater 

contours) of the releases at the facility and is an open bedrock well approximately 600 feet deep. 

Therefore, it is unlikely the detections observed in the well are related to releases at the facility 

and could be attributed to other adjacent sources. Regardless, MEARNG capped and closed the 

drinking water fountains connected to this well following an SL exceedance of PFOA in 2018. 

Given this information, the pathway for exposure to site workers via ingestion of groundwater is 

considered incomplete. Off-facility, there are five potable wells within 1-mile of the facility. 

According to the Maine Geological Survey, these wells are open bedrock boreholes and range in 

depths from 65-425 feet bgs. Additionally, none of these wells are immediately downgradient of 

the facility (using the facility-specific groundwater contours). Given the degree of uncertainty in 

the groundwater flow direction on and surrounding the facility, as well as, the uncertainty in 

hydraulic communication between the overburden and bedrock aquifers, conservatively the 

pathway for exposure to off-facility residents via ingestion of groundwater is considered potentially

complete with an exceedance of the SL. Finally, depths to water measured at AOI 2 in April 2022 

during the SI ranged from 1.52 to 9.23 feet bgs. Therefore, the ingestion exposure pathway for 

future construction workers is considered potentially complete. The CSM for AOI 2 is presented 

on Figure 7-2. 

7.3 Surface Water and Sediment Exposure Pathway

No surface water and sediment samples were collected during the SI. However, 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 potential

source and potential receptors.

7.3.1 AOI 1 and AOI 2

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 and AOI 2, it is possible that those compounds may have migrated from soil and 

groundwater to the channel segment of Birch Stream adjacent to the facility. Given the shallow 

groundwater elevations and the depth of the domestic channel it is possible that groundwater 

could flow off-facility and into the channel which could then flow into Kenduskeag Stream.

Therefore, the surface water and sediment ingestion exposure pathway for residents, or 

recreational user/trespassers is considered potentially complete.
Site Inspection Report

Bangor Training Site, Bangor Maine

AECOM 7-4

THIS PAGE INTENTIONALLY BLANK
Media

SOURCE PATHWAY RECEPTOR

AOI 1

AFFF fire 

suppression

system release

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 

Worker3 Resident1,2 Trespasser/ Recreational User1

Site 

Worker

Construction 

Worker3 Resident1,2

/ / / /

/ / / /

/ / / /

/ / /

LEGEND

Figure 7-1

Conceptual Site Model, AOI 1

Bangor Training Site

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

Trespasser/ 

Recreational User1

1. The resident and recreational users refer to offsite receptors.

2. Inhalation of dust for off-site receptors is likely

insignificant.

3. No current active construction at the facility.

Notes:

/

7-5
Media

SOURCE PATHWAY RECEPTOR

AOI 2

Jet-X fire 

suppression

system release

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 

Worker3 Resident1,2 Trespasser/ Recreational User1

Site 

Worker

Construction 

Worker3 Resident1,2

/ / / /

/ / / /

/ / / /

/ / /

LEGEND

Figure 7-2

Conceptual Site Model, AOI 2

Bangor Training Site

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

Trespasser/ 

Recreational User1

1. The resident and recreational users refer to offsite receptors.

2. Inhalation of dust for off-site receptors is likely

insignificant.

3. No current active construction at the facility.

Notes:

/

7-6
Site Inspection Report

Bangor Training Site, Bangor Maine

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 19 to 29 April 2022 and consisted of utility clearance, 

HSA borings, soil sample collection, temporary monitoring well installation, grab groundwater

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

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

To fulfill the project DQOs set forth in the approved SI QAPP Addendum (AECOM, 2021), samples 

were collected and analyzed for a subset of 18 compounds by LC/MS/MS compliant with QSM 5.3 

Table B-15 as follows.

• Seventeen (17) soil samples from six boring locations; 

• Six grab groundwater samples from six temporary wells; 

• Twelve (12) 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 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 potential source and potential receptors for potential exposure at the AOIs,

which are described in Section 7.

8.2 Outcome 

Based on the results of this SI, further evaluation is warranted in an RI for AOI 1 and AOI 2. 

Sample analytical concentrations collected during the SI were compared to the project SLs in soil 

and groundwater, as described in Table 6-1. A summary of the results of the SI data relative to 

the SLs is as follows:

At AOI 1:

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

1 were below their SLs. 

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

of 6 ng/L, with a maximum concentration of 3,210 ng/L at location AOI01-03. PFOS 

exceeded the SL of 4 ng/L, with a maximum concentration of 75.2 ng/L at location 

AOI01-01. PFNA exceeded the SL of 6 ng/L, with a maximum concentration of 94.5

ng/L at location AOI01-03. PFHxS and PFBS were detected below their respective 

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

At AOI 2:

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

2 were below their SLs. 
Site Inspection Report

Bangor Training Site, Bangor Maine

AECOM 8-2

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

SL of 6 ng/L, with a maximum concentration of 15.7 ng/L at location AOI02-04. PFOS 

exceeded the SL of 4 ng/L, with a maximum concentration of 14.8 ng/L at location 

AOI02-04. PFHxS exceeded the SL of 39 ng/L, with a maximum concentration of 89

ng/L at location AOI02-04. PFNA and PFBS were detected below their respective SLs. 

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

The topography at the facility and surrounding area would suggest that the groundwater flow 

direction is southeast; however, site-specific groundwater flow collected during this SI indicates 

that groundwater flows west, as shown in Figure 2-4. This could in part be due to shallow bedrock 

observed at AOI 2 (bedrock was identified as shallow as 3.3 feet bgs). The observed shallow 

depth to water measurements may be indicative of a bedrock high or other subsurface feature 

impacting the groundwater flow underlying the facility. Further evaluation is required to refine the 

groundwater flow direction.

Lastly, one of the two equipment blanks had detections of PFOS at 0.913 ng/L. More discussion 

about this equipment blank detection can be found in Appendix A. 

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

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

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

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

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

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

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

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

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

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

AOI Potential 

Release Area

Soil –

Potential 

Source Area

Groundwater –

Potential Source 

Area

Groundwater – 

Facility Boundary Future Action

1 Building 260 Proceed to RI 

2 Building 254 Proceed to RI

Legend:

= detected; exceedance of the screening levels

= detected; no exceedance of the screening levels

= not detected
Site Inspection Report

Bangor Training Site, Bangor Maine

AECOM 9-1

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