FINAL 

Site Inspection Report 

Fargo Army Aviation Support Facility #2 

Fargo, North Dakota 

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) 

ARNG Installations, Nationwide

October 2023 

Prepared for: 

Army National Guard Headquarters 

111 S. George Mason Drive 

Arlington, VA 22204 

UNCLASSIFIED
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TABLE OF CONTENTS

Page

LIST OF APPENDICES ................................................................................................................ iii

LIST OF FIGURES ....................................................................................................................... iv

LIST OF TABLES .......................................................................................................................... v

LIST OF ACRONYMS AND ABBREVIATIONS ...................................................................... vi

EXECUTIVE SUMMARY ...................................................................................................... ES-1

1. INTRODUCTION ............................................................................................... 1-1

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

1.2 Site Inspection Purpose ............................................................................ 1-1

2. FACILITY BACKGROUND.............................................................................. 2-1

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

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

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

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

2.2.3 Hydrology ................................................................................. 2-3

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

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

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

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

3. SUMMARY OF AREAS OF INTEREST........................................................... 3-1

3.1 AOI 1 – Hangar ........................................................................................ 3-1

3.2 Adjacent Sources ..................................................................................... 3-1

3.2.1 Building 215 – Former Fire Station .......................................... 3-1

3.2.2 Building 217 – Main Hangar .................................................... 3-1

3.2.3 Aircraft Parking Apron ............................................................. 3-2

3.2.4 Nozzle Testing Area - North of Apron ..................................... 3-2

3.2.5 Former Fire Training Area – ERP Site 10 ................................ 3-2

3.2.6 Nozzle Testing Area - South of Building 340 .......................... 3-2

3.2.7 Nozzle Testing Area – East of Building 340 ............................ 3-2

3.2.8 Stormwater Outfalls #2 and #3 ................................................. 3-2

3.2.9 Soil Stockpile Area ................................................................... 3-3

4. PROJECT DATA QUALITY OBJECTIVES ..................................................... 4-1
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4.1 Problem Statement................................................................................... 4-1

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

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

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

4.5 Data Usability Assessment ...................................................................... 4-2

5. SITE INSPECTION ACTIVITIES......................................................................5-1

5.1 Pre-Investigation Activities ..................................................................... 5-2

5.1.1 Technical Project Planning .......................................................5-2

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

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

5.2 Soil Borings and Soil Sampling............................................................... 5-3

5.3 Temporary Well Installation and Groundwater Grab Sampling.............. 5-4

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

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

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

5.7 Laboratory Analytical Methods............................................................... 5-6

5.8 Deviations from SI UFP-QAPP Addendum ............................................ 5-6

6. SITE INSPECTION RESULTS ..........................................................................6-1

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

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

6.3 AOI 1 – Hangar........................................................................................ 6-2

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

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

6.3.3 Conclusions...............................................................................6-3

7. EXPOSURE PATHWAYS..................................................................................7-1

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

7.1.1 AOI 1 – Hangar.........................................................................7-2

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

7.2.1 AOI 1 – Hangar.........................................................................7-2

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

7.3.1 AOI 1 – Hangar.........................................................................7-3

8. SUMMARY AND OUTCOME ..........................................................................8-1

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

8.2 Outcome................................................................................................... 8-1
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9. REFERENCES .................................................................................................... 9-1

LIST OF APPENDICES

Appendix A. Data Usability Assessment and Validation Reports 

Appendix B. Field Documentation

B1. Log of Daily Notice of Field Activities

B2. Sampling Forms 

B3. Survey Data 

Appendix C. Photographic Log 

Appendix D. Technical Project Planning Meeting Minutes

Appendix E. Boring Logs and Well Construction Diagrams

Appendix F. Analytical Results

Appendix G. Laboratory Reports
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LIST OF FIGURES

Figure 2-1 Facility Location

Figure 2-2 Facility Topography

Figure 2-3 Groundwater Features

Figure 2-4 Surface Water Features

Figure 2-5 Groundwater Elevations, May 2022

Figure 3-1 Areas of Interest

Figure 3-2 Adjacent Sources

Figure 5-1 Site Inspection Sample Locations

Figure 6-1 PFOS Detections in Soil

Figure 6-2 PFOA Detections in Soil

Figure 6-3 PFBS Detections in Soil

Figure 6-4 PFHxS Detections in Soil

Figure 6-5 PFNA Detections in Soil

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

Figure 6-7 PFHxS and PFNA Detections in Groundwater

Figure 7-1 Conceptual Site Model, AOI 1 
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LIST OF TABLES

Table ES-1 Screening Levels (Soil and Groundwater)

Table ES-2 Summary of Site Inspection Findings and Recommendations

Table 5-1 Samples by Medium, Fargo AASF #2, North Dakota, Site Inspection Report

Table 5-2 Soil Boring Depths and Temporary Well Screen Intervals, Fargo AASF #2, North 

Dakota, Site Inspection Report

Table 5-3 Groundwater Elevation, Fargo AASF #2, North Dakota, Site Inspection Report

Table 6-1 Screening Levels (Soil and Groundwater)

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

Report, Fargo AASF #2

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

Site Inspection Report, Fargo AASF #2

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

Inspection Report, Fargo AASF #2

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

Report, Fargo AASF #2

Table 8-1 Summary of Site Inspection Findings and Recommendations
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LIST OF ACRONYMS AND ABBREVIATIONS

°C Degrees Celsius 

°F Degrees Fahrenheit 

% Percent

μg/kg Microgram(s) per kilogram

μg/L Microgram(s) per liter

AASF Army Aviation Support Facility 

AECOM AECOM Technical Services, Inc. 

AFFF Aqueous Film Forming Foam

amsl Above mean sea level

AOI Area of Interest

ARNG Army National Guard

bgs Below ground surface

bmsl Below mean sea level

btoc Below top of casing

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

DPT Direct-push technology

DQI Data quality indicator

DQO Data quality objective

DUA Data Usability Assessment

EA EA Engineering, Science, and Technology, Inc., PBC

EIS Extraction internal standards

ELAP Environmental Laboratory Accreditation Program

EM Engineer Manual

EB Equipment Blank 

FB Field blank

FedEx Federal Express

ft Foot (feet)

FTA Fire Training Area

GPR Ground-penetrating radar

HDPE High-density polyethylene

HFPO-DA Hexafluoropropylene oxide dimer acid

HQ Hazard Quotient
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IDW Investigation-derived waste

ITRC Interstate Technology Regulatory Council

LC/MS/MS Liquid chromatography tandem mass spectrometry

LCS Laboratory control sample 

LCSD Laboratory control sample duplicate

LLC Limited Liability Company

LOQ Limit of quantification

MS Matrix spike

MSD Matrix spike duplicate

NDANG North Dakota Air National Guard

NDARNG North Dakota Army National Guard

NDDEQ North Dakota Department of Environmental Quality

NELAP National Environmental Laboratory Accreditation Program 

ng/L Nanogram(s) per liter

No. Number

OSD Office of the Secretary of Defense

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

PVC polyvinyl chloride

QA Quality assurance

QAPP Quality Assurance Project Plan

QC Quality control

QSM Quality Systems Manual

RI Remedial investigation 

RPD Relative percent difference

SI Site Inspection

SL Screening level

TOC Total organic carbon

TPP Technical Project Planning
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UFP Uniform Federal Policy

USACE U.S. Army Corps of Engineers

USEPA U.S. Environmental Protection Agency

Wood Wood Environment & Infrastructure Solutions, Inc.

WSP WSP USA Environment & Infrastructure, Inc.
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EXECUTIVE SUMMARY

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

Inspections (SIs) at ARNG facilities nationwide based on the current or potential historical use of 

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

memorandum regarding Investigating Per- and Polyfluoroalkyl Substances within the 

Department of Defense Cleanup Program (Assistant Secretary of Defense, 2022) from the Office 

of the Secretary of Defense (OSD) dated 6 July 2022. The six compounds listed in the OSD 

memorandum include perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), 

perfluorobutanesulfonic acid (PFBS), perfluorononanoic acid (PFNA), perfluorohexanesulfonic 

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

. These compounds are 

collectively referred to as “relevant compounds” throughout the document, and the applicable 

screening levels (SLs) are provided below in Table ES-1.

The PA identified one Area of Interest (AOI) where PFAS-containing materials may have been 

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

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

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 a comparison of 

SI results to screening levels (SLs) for the relevant compounds. This SI was completed at the 

Fargo Army Aviation Support Facility (AASF) #2 in Fargo, North Dakota and determined that 

no further investigation by DoD (ARNG G-9) is warranted for AOI 1: Hangar. The Fargo AASF 

#2 will be referred to as the “Facility” throughout this document. 

The Facility, operated by North Dakota ARNG (NDARNG), encompasses approximately 0.40 

acres in Fargo, North Dakota. The Facility is in Cass County, approximately one mile northwest 

of Fargo, North Dakota. The Facility is surrounded on all sides by the Hector International 

Airport. Fargo AASF #2 is constructed on a parcel of land that is owned by the Hector 

International Airport, under an operational lease by Fargo Jet Center Limited Liability Company 

(LLC), and has been operated by the NDARNG from 2012 to present (AECOM Technical 

Services, Inc. [AECOM], 2020). 

The PA identified one AOI for investigation during the SI phase. SI sampling results from the 

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

the results of this SI, and following the Comprehensive Environmental Response, Compensation, 

and Liability Act (CERCLA) process, further evaluation of the contamination of groundwater 

confirmed at the Facility is warranted. However, surface soil data suggests the source(s) of 

contamination is not the result of NDARNG activities at the Facility. Therefore, no further 

investigation by DoD (ARNG G-9) is warranted at this time.

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)

Analyte1,2

Residential (Soil) 

(μg/kg)1 

(0-2 feet bgs)

Industrial / Commercial

Composite Worker (Soil) 

(μg/kg)1 

(2-15 feet bgs)

Tap Water

(Groundwater)

(ng/L)1 

PFOA 19 250 6

PFOS 13 160 4

PFBS 1,900 25,000 601

PFHxS 130 1,600 39

PFNA 19 250 6

Notes:

1. Assistant Secretary of Defense. July 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. May 2022. 

2. 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.

Abbreviations: 

μg/kg = microgram(s) per kilogram

bgs = below ground surface

ng/L = nanogram(s) per liter

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

AOI

Potential Release 

Area

Soil – 

Adjacent to 

Potential 

Source Area1 

Groundwater –

Adjacent to 

Potential Source 

Area1,2 Future Action

1 Hangar No Further Action

Legend:

 = Detected; exceedance of screening levels

 = Detected; no exceedance of screening levels

 = Not detected

1 All samples collected to assess AOI were collected adjacent to the potential source 

area and were located off-Facility. 

2 Groundwater exceedance not associated with DoD release; no further action by 

ARNG G-9.
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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) at ARNG facilities nationwide based on the current 

or potential historical use of per- and polyfluoroalkyl substances (PFAS) with a focus on the six 

compounds presented in the memorandum regarding Investigating Per- and Polyfluoroalkyl 

Substances within the Department of Defense Cleanup Program (Assistant Secretary of Defense, 

2022) from the Office of the Secretary of Defense (OSD) dated 6 July 2022. The six compounds 

listed in the OSD memorandum are referred to as “relevant compounds” throughout this 

document and include perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), 

perfluorobutanesulfonic acid (PFBS), perfluorononanoic acid (PFNA), perfluorohexanesulfonic 

acid (PFHxS), and hexafluoropropylene oxide dimer acid (HFPO-DA)1. The ARNG performed 

this SI at the Fargo Army Aviation Support Facility (AASF) #2 in Fargo, North Dakota. The 

Fargo AASF #2 is also referred to as the “Facility” throughout this report.

The SI project elements were performed in accordance with the Comprehensive

Environmental Response, Compensation, and Liability Act (CERCLA) (U.S. Environmental

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

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

compliance with U.S. Department of Army (DA) requirements and guidance for field 

investigations.

1.2 SITE INSPECTION PURPOSE

A PA was performed at the Fargo AASF #2 (AECOM Technical Services, Inc. [AECOM], 2020) 

that identified one Area of Interest (AOI) where PFAS-containing materials may have been used, 

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

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

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

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

1 Of the six PFAS compounds presented in the 6 July 2022 OSD memorandum, HFPO-DA (commonly referred to as 

GenX) was not included as an analyte at the time of this SI. Based on the conceptual site model (CSM) developed 

during the PA and revised based on SI findings, the presence of HFPO-DA is not anticipated at the facility because 

HFPO-DA is generally not a component of military specification (MIL-SPEC) aqueous film forming foam (AFFF) 

and based on its history including distribution limitations that restricted use of GenX, it is generally not a component 

of other products the military used. In addition, it is unlikely that GenX would be an individual chemical of concern 

in the absence of other PFAS.
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2. FACILITY BACKGROUND

2.1 FACILITY LOCATION AND DESCRIPTION

The Facility is in Cass County, approximately one mile northwest of Fargo, North Dakota and is 

surrounded on all sides by the Hector International Airport (Figure 2-1). The Facility is 

accessible from North University Drive from the east and 19th Avenue North from the south. The 

Facility is constructed on a parcel of land that has been leased from the Fargo Jet Center LLC

since 2012 on two separate leases, one from 2012 to 2015, and the current one from 2016 to 

present. The current lease ends on 30 September 2023 with the option of two more one-year 

lease extensions. Before 2012, the Fargo Jet Center LLC leased the site to other operators who 

used the hangar facility for aircraft and other equipment storage. Fargo AASF #2 consists of one 

hangar and one administrative building, which is a portion of a larger building complex with 

other users or operators not associated with NDARNG. 

2.2 FACILITY ENVIRONMENTAL SETTING

The Facility is surrounded on all sides by the Hector International Airport, with the airfield 

located just northwest of the Facility. The 119th Wing of the North Dakota Air National Guard 

(ANG), Hector Field ANG Base, is located approximately 1000 feet northeast of the Facility. 

The land just north of the Hector ANG Base consists of several cemeteries. The areas beyond the 

airport property are residential and commercial to the east and south and agricultural to the north

and west. The Facility lies within the Red River Valley of North Dakota, which is characterized 

by glacial lake sediments. The Facility is approximately 2 miles west of the Red River and 

approximately 5 miles southwest of the Sheyenne River. The elevation of the Facility is 

approximately 904 feet above mean sea level (amsl) (AECOM, 2020).

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

current and future land use, sensitive habitat, and threatened/endangered species. The topography 

and the Facility are shown on Figure 2-2. The regional geology and groundwater features are 

shown on Figure 2-3. The regional surface water features and drainage basins are shown on 

Figure 2-4. Groundwater elevations and contours are presented on Figure 2-5.

2.2.1 Geology

The Facility lies within the southeastern side of the state of North Dakota, in Cass County, within 

the Drift Prairie area and the Red River Valley. Fargo is a part of the Central Lowland, which is 

covered with glacial deposits. In the glacial deposits in Cass County, there are four major surface 

units; they are defined as ground moraine, lake plain, shore, and deltaic deposits. Ground 

moraine can be found within the first 20 feet below the surface and is composed of till, silt, 

gravel, sand, heterogeneous mixture of clay, and boulders with clay and silt predominating. The 

lake plain deposits consist of silt and clay that can be found as two separate layers in the lake 

plain deposit. The silt unit comprises the surface deposits with a lower-level clay unit. The two 

layers are marked by desiccation and vegetal remnant. The deposits known as “shore” border the 

lake plain on the west side and consist of silt, clay, sand, and gravel. They are typically the 

smallest layer and only range to 15 feet maximum depth. Deltaic deposits consist of fine to 

medium sand and silt and can range to 120 feet deep. These four layers overlie sedimentary 
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rocks from the Cretaceous age, except in places where the Cretaceous shale eroded, in which 

case, the layers sit on Precambrian crystalline rocks (AECOM, 2020).

The underlying rock from the glacial deposits consist of three Cretaceous bedrock units that can

be defined as the Greenhorn Formation, Graneros Shale, and Dakota Sandstone, altogether lying

200-650 feet below the surface. In a few areas, Precambrian crystalline rocks can be found,

consisting of red and green clay derived from granite, but these rocks are only found at depths

over 900 feet below ground surface (North Dakota Geological Survey, 1949; AECOM, 2020).

During the SI, five borings were advanced between 6 to 15 feet (ft) below ground surface (bgs). 

The soil was classified as clay containing some fine materials at all boring locations with the 

exception being a sand layer encountered from 4.5 to 5 ft bgs at AOI01-02. The grain size 

analysis conducted on the soil samples collected from the AOI confirms the field observation of 

fine-grained soils consisting of clay and silt. 

2.2.2 Hydrogeology

The Facility is just east of the Red River of the North Drainage Basin, located to the west and 

northwest of several surficial aquifers (West Fargo North, West Fargo South, Nodak, and Fargo 

Aquifers). North Dakota’s surficial aquifers consist of sand and gravel. The surficial aquifers 

range from tens to hundreds of feet thick and are quite discontinuous (North Dakota 

Environmental Quality, 2021). The recharge to the aquifers can happen in two possible ways: 

through precipitation from upland areas and water that comes from the sandstone layers, as it 

moves laterally into the recharge areas, and from percolation in gravel aquifers, which extends 

into lake deposits resting on underlying till (North Dakota Geological Survey, 1968; AECOM, 

2020). 

The groundwater within the Nodak aquifer flows into the Fargo, West Fargo North and the West 

Fargo South Aquifers (Ripley, 2000; AECOM, 2020). No potable water wells are located within 

the boundary of the Facility; however, monitoring/observation, domestic, and commercial wells 

exist within 2 miles of the Facility. The closest commercial well is approximately 0.8 miles north 

of the Facility.

Depth to groundwater at the Facility as measured in May 2022 during the SI ranged from 2.1 to 

3.7 ft bgs. Synoptic water level measurements taken from temporary monitoring wells during the 

SI fieldwork (see Section 5.4) did not indicate a clear localized groundwater flow direction. The 

area received approximately 1 inch of rain on 9 May 2022 (National Centers for Environmental 

Information [NCEI 2022]), 2022), and the groundwater elevations measured at the temporary 

wells during the SI were likely still showing the effects of the precipitation. The depth to the 

water table fluctuates seasonally (with a depth to the high-water table of approximately 1 ft bgs 

following the spring thaw in April through June), the typical depth to groundwater ranges from 

approximately 4 to 10 ft bgs (SAIC, 2013; ANG, 2019). Given the shallow depth to 

groundwater, it is possible that local groundwater may flow preferentially with stormwater 

runoff that is managed with storm sewers, culverts, and ditches. It is also likely that shallow 

groundwater intersects the Facility’s stormwater drainage structures and interacts with 

stormwater runoff. The regional groundwater flow direction is generally from west to east 

(HMTC, 1987; ANG, 2019). Groundwater elevations from the SI are presented in Figure 2-5. 
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Drinking water for the Facility is supplied by the City of Fargo, which sources water from the 

Red River, Sheyenne River and Lake Ashtabula (City of Fargo, 2019; AECOM, 2020).

2.2.3 Hydrology

No naturally occurring drainage systems, streams, or bodies of water are located at the Facility.

Natural drainage at the Facility and surrounding airport are not well defined due to the flat

topography. Stormwater runoff is managed via the Hector International Airport’s stormwater 

system using a series of storm sewers, culverts, and ditches that flow to several open man-made 

ditches; these in turn flow north and east to the Red River, which lies about 2 miles east of the 

Facility (ANG, 2019; AECOM, 2020). Due to the man-made features, the surface water flow at 

the Facility flows primarily to the northeast and partially to the southwest (Figure 2-4). The 

general regional surface water flow is east toward the Red River.

2.2.4 Climate

The climate at the Facility consists of four clearly separated seasons, with shorter, warm

summers and freezing, snowy, cloudy, windy winters. Temperatures vary from average highs of

70.2 degrees Fahrenheit (°F) to average lows of 6.3 °F. The average annual temperature is 40.5

°F. Average precipitation is 20.8 inches of rain (World Climate, 2019; AECOM, 2020). 

2.2.5 Current and Future Land Use

The Facility is a controlled access facility with publicly accessible roads and is surrounded on all 

sides by the Hector International Airport. The Facility consists of one hangar and one 

administrative building. The anticipated future land use is not expected to change from the 

current land use.

Future improvements, land acquisitions, and land use controls at the Hector International Airport 

are unknown. In 2016, the Hector International Airport proposed an $81 million dollar expansion 

and improvement project. Some improvements include runway expansion, additional 

hangars/buildings, main terminal expansion, and additional public parking additions (AECOM, 

2020). 

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 species are listed as federally endangered, threatened, proposed, and/or candidate 

species in Cass County, North Dakota (U.S. Fish and Wildlife Services, 2021):

Insects: Monarch Butterfly Danaus plexippus (Endangered)

Mammals: Northern Long-eared Bat, Myotis septentrionalis (Endangered)
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2.3 HISTORY OF PFAS USE

Aqueous film forming foam (AFFF), a firefighting agent, was commonly used by the U.S. 

military to extinguish petroleum fires, for firefighting training, and for the suppression of fires in 

uncontained areas. Military use of AFFF began in the 1970s and was most widely used at 

Department of Defense (DoD) installations with airfields. The Hangar was identified as a 

potential PFAS release area at the Facility during the PA (AECOM, 2020). One Tri-MaxTM 30 

fire extinguisher was found in the building under tarps and other supplies. Personnel were not 

aware that the Tri-MaxTM 30 was at the Facility, where the fire extinguisher originated from, or 

how long it was at the Facility. One interviewee indicated that the Tri-MaxTM 30 has not been 

used since NDARNG arrived at the Facility in 2012. A description of the AOI is presented in 

Section 3. 
Army National Guard Site Inspections

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Figure 2-1

Facility Location

3

Facility Data

Facility Boundary

Potential PFAS Release

North Dakota Air National Guard

Base Investigation Boundaries

Approximate Hector International 

Airport Boundary

ND ^_

Data Sources: 

ESRI 2020

AECOM 2020

Date:............................January 2023

Prepared By:..............................WSP

Prepared For:.........................USACE

Projection:.......NAD 1983 StatePlane

G:\ANG\a_MXD\Fargo,ND\Facility Location.mxd - dylan.jones - 6/23/2023 - 1:26:31 PM

Facility Boundary

0 0.25 0.5 1 1.5 2

Miles
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Figure 2-2

Facility Topography

Facility Boundary

895

900

890

885

880

875

870

905

910

900

895

900

900

895

895

880

900

890

895

895

900

895

885

900

900

895

900

895 900

895

900

900

900

895

900

895

895

900

900

895

900

900

895

895

900

895

900

900

895

915

890

895

900

900

900

3

Facility Data

Facility Boundary

Potential PFAS Release

Approximate Hector International 

Airport Boundary

North Dakota Air National

Guard Base Investigation

Boundaries (NDANGB)

ND ^_

Data Sources: 

ESRI 2020

AECOM 2020

Date:...........................January 2023

Prepared By:.............................WSP

Prepared For:........................USACE

Projection:......NAD 1983 StatePlane

G:\ANG\a_MXD\Fargo,ND\Facility Topo.mxd - dylan.jones - 6/23/2023 - 1:30:52 PM

0 0.1 0.2 0.4 0.6 0.8

Miles

Topography

Elevation Contour (10 ft. interval)
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Figure 2-3

Groundwater Features

A@

A@

A@ A@

A@

A@

A@

!P

!P

!P

!P

A@

A@

!P

!P

A@

!P

A@A@

!P !P

A@

!P

!P !P

!P

!P

!P

!P

!P

!P

!P !P

A@

A@ A@

A@

A@

A@

A@

A@

A@

A@

A@

A@

A@A@ A@

A@ A@

A@

A@

A@

A@

A@

A@

A@

A@

A@

!P

A@

A@

!P

A@

!P

A@

A@

!P

A@

A@

Red River of the North

Sewer

Treatment Plant

3

Facility Data

Facility Boundary

Approximate Hector International Airport

Boundary

North Dakota Air National Gaurd Base

Investigation Boundaries (NDANGB)

ND ^_

Data Sources:

ESRI 2020

AECOM 2020

North Dakota state

agencies and the

ND GIS Hub

Date:..............................January 2023

Prepared By:...............................WSP

Prepared For:..........................USACE

Projection:........NAD 1983 StatePlane

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0 2,250 4,500 9,000

Feet

A@ A@

A@

A@

A@

0 190 380 760 Feet

Nodak Aquifer

West Fargo North Aquifer

Fargo Aquifer

Hydrology Features

!P Commercial Well

!P Domestic Well

A@ Monitoring Well

Shallow Local Groundwater Flow

Direction from SI

General Regional Groundwater

Flow Direction

Surficial Aquifers
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Figure 2-4

Surface Water Features

Red River of the North

Sewer

Treatment Plant

3

Facility Data

Facility Boundary

Onsite Potential PFAS Release

Approximate Hector

International Airport Boundary

North Dakota Air National

Gaurd Base Investigation

Boundaries (NDANGB)

ND ^_

Data Sources:

ESRI 2020

AECOM 2020

Date:............................January 2023

Prepared By:..............................WSP

Prepared For:.........................USACE

Projection:.......NAD 1983 StatePlane

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0 0.15 0.3 0.6 0.9 1.2

Miles

A@ A@

A@

A@

A@

0 190 380 760 Feet

Hydrology Features

Shallow Local Groundwater Flow

Direction from SI

General Regional Groundwater

Flow Direction

Unnamed Tributaries

Surface Runoff Direction
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Figure 2-5

Groundwater Elevation, May 2022

") #*

#* #*

")

894

893

894

AASF2-01

894.33

AOI01-01

892.67

AOI01-02

894.39

AOI01-03

894.53

AOI01-04

893.59

3

Facility Data

Facility Boundary

Area of Interest

Potential PFAS Release

ND ^_

Data Sources:

ESRI 2020

AECOM 2020

Date:...........................January 2023

Prepared By:.............................WSP

Prepared For:.........................USACE

Projection:.......NAD 1983 StatePlane

G:\ANG\a_MXD\Fargo,ND\GroundwaterElevation_5_2022.mxd - dylan.jones - 7/7/2023 - 1:02:07 PM

0 75 150 300 450

Feet

AOI

TriMaxTM30

Location

Administrative

Building

Hanger

Hydrology Features

General Regional Groundwater Flow

Direction

Shallow Local Groundwater Flow

Direction from SI

Groundwater Contours

Inferred Groundwater Contours
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3. SUMMARY OF AREAS OF INTEREST

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

or released historically. One potential release area was identified at the Facility and identified as: 

AOI 1 Hangar. The AOI is shown on Figure 3-1.

3.1 AOI 1 – HANGAR

AOI 1 is comprised of the hangar portion of the building, which is a portion of a larger complex 

not operated by NDARNG. One Tri-MaxTM 30 fire extinguisher was identified at the Facility

inside the Hangar. The Facility’s current personnel and interviewees were not aware that the TriMaxTM 30 extinguisher was in the Hangar and did not know when it arrived at the Facility. No 

visible leaking or corrosion were noted on the fire extinguisher. According to NDARNG 

personnel, the Tri-MaxTM 30 fire extinguisher was removed from the Facility and transported to 

Bismarck AASF #1 the week of 7 February 2020. Subsequently, the Tri-MaxTM 30 extinguisher 

was emptied of its contents and the AFFF liquid was shipped offsite for disposal in November 

2020. None of the NDARNG personnel had ever worked or trained with the Tri-MaxTM 30 

extinguisher. Due to the lack of information regarding the Tri-MaxTM 30 fire extinguisher, the 

Hangar was identified as an AOI. There are trench drains in the Hangar that lead to an oil/water 

separator and then to the Fargo Sanitary Wastewater Treatment Plant (AECOM, 2020). Potential

exposure from this AOI could occur as a result of an undocumented use or release of AFFF from

the Tri-MaxTM 30 fire extinguisher in the Hangar location. A release of AFFF could potentially

flow through the doors located on either side of the Hangar and impact the soil and/or

groundwater. 

3.2 ADJACENT SOURCES

An SI was completed at Hector Field Air National Guard Base. Hector Field is the home of the 

119th Fighter Wing. North Dakota Air National Guard (NDANG) was formed in 1947 and 

occupies approximately 209 acres of the Hector International Airport, northeast of the Fargo

AASF #2. A description of each off-facility source associated with Hector Field is presented 

below and shown on Figure 3-2.

3.2.1 Building 215 – Former Fire Station

Building 215, the Main Base Former Fire Station, was used from the 1950s to 2011 and is 

located northeast and cross-gradient of the Fargo AASF#2. AFFF was stored in fire rescue 

vehicles, and a known discharge of 180 gallons of AFFF into the building’s floor drains occurred 

in 2001. Although the soil samples did not exceed the NDANG SI screening levels, additional 

sampling was proposed to determine the nature and extent in the vertical/horizontal directions 

(AECOM, 2020).

3.2.2 Building 217 – Main Hangar

Building 217, the Main Base Hangar, was equipped with AFFF fire suppression systems since 

1992. Building 217 is located northeast and cross-gradient of the Fargo AASF#2. Regular AFFF 

fire suppression system testing was conducted from 1992 to 2014. Although the soil samples did 
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not exceed the NDANG SI screening levels, additional sampling was proposed to determine the 

nature and extent in the vertical/horizontal directions. PFAS contamination levels in groundwater 

did exceed the NDANG SI screening levels (AECOM, 2020).

3.2.3 Aircraft Parking Apron

An aircraft parking apron, where potential AFFF releases may have occurred, is located 

northeast and cross-gradient of the Fargo AASF#2. Although soil samples did not exceed the 

NDANG SI screening levels, additional sampling was proposed to determine the nature and 

extent in the vertical/horizontal directions. PFAS contamination in groundwater exceeded the 

NDANG SI screening levels (AECOM, 2020).

3.2.4 Nozzle Testing Area - North of Apron

Documented nozzle testing using AFFF occurred in this area, located northeast and crossgradient of the Fargo AASF #2. Although the soil samples did not exceed the NDANG SI 

screening levels, additional sampling was proposed to determine the nature and extent in the 

vertical/horizontal directions. PFAS contamination levels in groundwater exceeded the NDANG 

SI screening levels (AECOM, 2020).

3.2.5 Former Fire Training Area – ERP Site 10

Former on-Base Fire Training Area (FTA), used from the 1950s through mid-1989, is located 

northeast and cross-gradient of the Fargo AASF#2. AFFF was likely utilized during this time. 

PFOS concentrations in soil exceeded the NDANG SI screening levels and additional sampling 

was proposed to determine the nature and extent in the vertical/horizontal directions (AECOM, 

2020).

3.2.6 Nozzle Testing Area - South of Building 340 

Documented nozzle testing using AFFF occurred in this area, located northeast and crossgradient of the Fargo AASF #2. Although the soil and groundwater samples did not exceed the 

NDANG SI screening levels, additional sampling was proposed to determine the nature and 

extent in the vertical/ horizontal directions (AECOM, 2020).

3.2.7 Nozzle Testing Area – East of Building 340 

Documented nozzle testing using AFFF occurred in this area, located northwest and crossgradient of the Fargo AASF#2. Although the soil and groundwater samples did not NDANG SI 

screening levels, additional sampling was proposed to determine the nature and extent in the 

vertical/horizontal directions (AECOM, 2020).

3.2.8 Stormwater Outfalls #2 and #3

Stormwater Outfalls #2 and #3, which receive stormwater from several potential release 

locations potentially impacted by AFFF use, are located north/northeast and cross-gradient of the 

Fargo AASF#2. Although the sediment samples did not exceed the NDANG SI screening levels, 
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additional sampling was proposed upstream of the outfall and downstream outside the NDANG 

Base boundary to determine the nature and extent in the vertical/horizontal directions. PFAS

contamination levels in surface water exceeded the NDANG SI screening levels (AECOM, 

2020).

3.2.9 Soil Stockpile Area

The soil stockpile area received post land-farmed soils from the Former FTA-ERP Site 10, 

located northeast and cross-gradient of the Fargo AASF#2. Although the soil samples did not 

exceed the NDANG SI screening levels, additional sampling was proposed to determine the 

nature and extent in the vertical/horizontal directions. PFAS contamination levels in groundwater 

exceeded the NDANG SI screening levels (AECOM, 2020).
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Figure 3-1

Areas of Interest

3

Facility Data

Facility Boundary

Area of Interest

Potential PFAS Release

ND ^_

Data Sources:

ESRI 2020

Date:..........................October 2022

Prepared By:............................WSP

Prepared For:........................USACE

Projection:......NAD 1983 StatePlane

G:\ANG\a_MXD\Fargo,ND\AOI.mxd - dylan.jones - 6/28/2023 - 1:14:25 PM

Facility Boundary

0 75 150 300 450

Feet

AOI

TriMax30 TM

Location

Shallow Local Groundwater Flow

Direction from SI
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Figure 3-2

Adjacent Sources

Soils

Stockpile

Area

Stormwater

Outfall 002

Stormwater

Outfall 003

Nozzle Testing

Area- East of

Building 340

Nozzle Testing

Area- South of

Building 340

Former FTAERP Site 10

Building

215- Former

Fire Station

Building 217-

Main Hanger

Aircraft

Parking

Apron Nozzle Testing

Area- North

on Apron

3

Facility Data

Facility Boundary

Onsite Potential PFAS Release

Offsite Potential PFAS Release

Approximate Hector International

Airport Boundary

North Dakota Air National Gaurd

Base Investigation Boundaries

(NDANGB)

ND ^_

Data Sources:

ESRI 2020

AECOM 2020

Date:............................January 2023

Prepared By:..............................WSP

Prepared For:.........................USACE

Projection:.......NAD 1983 StatePlane

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0 0.05 0.1 0.2 0.3 0.4

Miles

A@ A@

A@

A@

A@

0 195 390 780 Feet

Hydrology Features

Shallow Local Groundwater Flow

Direction from SI

General Regional Groundwater

Flow Direction

Unnamed Tributaries
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4. PROJECT DATA QUALITY OBJECTIVES

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

Federal Policy (UFP)-Quality Assurance Project Plan (QAPP) Addendum (EA/Wood, 2022), the 

objective of the SI is to identify whether there has been a release to the environment at the AOI 

identified in the PA. For the 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 the presence or absence of relevant 

compounds at the sampled AOI.

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 for the SI include the following:

• The PA Report for Fargo Army Aviation Support Facility #2 (AECOM, 2020)

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

accordance with the site-specific UFP –QAPP Addendum (EA/Wood, 2022)

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

parameters measured at the time of sampling.

• Site Inspection Report for Perfluorooctane Sulfonate and Perfluoroocatanoic Acid at 

Hector Field Air National Guard Base Fargo, North Dakota (March 2019)

4.3 STUDY BOUNDARIES

The scope of the SI was horizontally bounded by the property limits of Fargo AASF #2. Due to 

the limited areas leased by NDARNG at the Fargo AASF #2, all sample locations were on 

airfield property (Figures 2-1 and 2-2). ARNG, through U.S. Army Corps of Engineers 

(USACE) (ARNG's agent), procured a fully executed right-of-entry to conduct the proposed offfacility sampling. The scope of the SI was bounded vertically by the depth of temporary 

monitoring wells installed within groundwater, where encountered (maximum depth of 15 feet 

bgs). Temporal boundaries were limited to the earliest available time field resources were 

available to complete the study.

4.4 ANALYTICAL APPROACH

Samples were analyzed by Eurofins, accredited under the DoD Environmental Laboratory 

Accreditation Program (DoD ELAP; Accreditation Number 1.01) and the National 

Environmental Laboratory Accreditation Program (NELAP; Certificate Number 021). Data were 

compared to applicable SLs within this document and decision rules as defined in the UFPQAPP Addendum (EA/Wood, 2022). 
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4.5 DATA USABILITY ASSESSMENT

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

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

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

and qualitative methods, the assessment determines whether project execution and the resulting 

data have met installation specific DQOs. Both sampling and analytical activities are considered 

to assess whether the collected data are of the right type, quality, and quantity to support the 

decision-making (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 UFP-QAPP (EA, 2020).
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5. SITE INSPECTION ACTIVITIES

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

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

implemented in accordance with the following approved documents. 

• Final Preliminary Assessment Report, Fargo Army Aviation Support Facility #2, 

North Dakota, dated August 2020 (AECOM, 2020)

• Final Programmatic Uniform Federal Policy-Quality Assurance Project Plan,

Site Inspections for Per- and Polyfluoroalkyl Substances Impacted Sites, ARNG 

Installations, Nationwide, dated December 2020 (EA, 2020)

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

Addendum, Fargo Army Aviation Support Facility #2, North Dakota dated 

February 2022 (EA/Wood, 2022)

• Final Programmatic Accident Prevention Plan, Revision 1, dated November 2020

(EA, 2020)

• Final Site Safety and Health Plan, Fargo Army Aviation Support Facility #2, 

North Dakota, dated November 2021 (EA/Wood, 2021). 

The SI field activities were conducted from 09 to 11 May 2022 and consisted of utility 

clearance, DPT boring and soil sample collection, temporary monitoring well installation, 

grab groundwater sample collection, and land surveying. Field activities were conducted 

in accordance with the UFP-QAPP Addendum (EA/Wood, 2022), except as noted in 

Section 5.8.

The following samples were collected during the SI and analyzed for 24 compounds via 

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

Version 5.3 Table B-15 to fulfill the project DQOs:

• Nine (9) soil samples from three locations (soil borings locations)

• Five (5) grab groundwater samples from five temporary well locations

• Eight (8) 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 medium. Field documentation is provided 

in Appendix B. A log of Daily Notice of Field Activity was completed throughout the SI 

field activities, which is provided in Appendix B1. Sampling forms are provided in 

Appendix B2, and land survey data are provided in Appendix B3. Additionally, a 

photographic log of field activities is provided in Appendix C. 
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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 of these activities are presented below. 

5.1.1 Technical Project Planning

The U.S. Army Corps of Engineers (USACE) TPP Process, Engineers Manual (EM) 200-1-2 

(Department of the Army 2016a) defines four phases to project planning: (1) defining the project 

phase; (2) determining data needs; (3) developing data collection strategies; and (4) finalizing the 

data collection plan. The process encourages stakeholder involvement in the SI, beginning with 

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

address the AOIs identified in the PA. 

A combined TPP Meeting 1 and 2 was held on 18 January 2022, 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 included ARNG, NDARNG, USACE, North Dakota Department of 

Environmental Quality (NDDEQ), 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 UFP-QAPP Addendum (EA/Wood, 

2022). 

A TPP Meeting 3 was held 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 results and findings, and future actions, where warranted. 

5.1.2 Utility Clearance

WSP USA Environment & Infrastructure, Inc. (WSP), previously doing business as Wood 

Environment & Infrastructure Solutions, Inc., contacted the North Dakota One Call to notify 

them of intrusive work at the Facility. WSP contracted GPRS, Inc. a private utility location 

service, to perform utility clearance at the Facility. Utility clearance was performed at each of the 

proposed boring locations on 09 May 2022 with input from the WSP field team. General locating 

services and ground-penetrating radar (GPR) were used to complete the clearance. Additionally, 

the first 5 feet of each boring were pre-cleared by WSP’s drilling subcontractor, Dakota 

Technologies, Inc., using a hand auger to verify utility clearance in shallow subsurface where 

utilities would typically be encountered. 

5.1.3 Source Water and PFAS Sampling Equipment Acceptability

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

acceptability criteria, as defined in the UFP-QAPP Addendum, prior to the start of field 

activities. A sample from a potable water source at Fargo AASF #2, was collected on 07

February 2022, prior to mobilization, and analyzed for PFAS by LC/MS/MS compliant with 

QSM 5.3 Table B-15 (DoD, 2020). The results of the sample of the potable water source used for 
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decontamination of drilling equipment during the SI are provided in Appendix F. A discussion 

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

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

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

environment was provided in the Standard Operating Procedures appendix to the Programmatic 

UFP-QAPP (EA, 2020). 

5.2 SOIL BORINGS AND SOIL SAMPLING

Soil samples were collected via DPT drilling methods in accordance with Standard Operating 

Procedure 047 Direct-Push Technology Sampling (EA, 2020). A Geoprobe® 66DT dual-tube 

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

used to collect soil from the top 5 ft of the boring in compliance with utility clearance 

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

provided in Table 5-1. One boring location was adjusted within a 5-feet offset for reasons 

including drill rig access, utility avoidance and bias toward sampling within observed drainage 

features.

Three discrete soil samples were collected for chemical analysis from each soil boring: one 

sample at the surface (0 to 2 ft bgs) and two subsurface soil samples. One subsurface soil sample 

was collected approximately 1 ft above the groundwater table, and one collected at the mid-point 

between the surface and the groundwater table. Total boring completion depths, to accommodate 

temporary well installation, ranged from 6 to 15 ft bgs. 

During the drilling, the soil cores were continuously logged for lithological descriptions by a 

field geologist using the Unified Soil Classification System. A photoionization detector (PID) 

was used to screen the breathing zone during boring activities as a part of personal safety 

requirements. Observations and measurements were recorded on sampling forms (Appendix B2) 

and in a non-treated field logbook. Depth interval, recovery thickness, PID concentrations, 

moisture, relative density, Munsell color, and Unified Soil Classification System texture were 

recorded. The boring logs are provided in Appendix E. 

Soil borings completed during the SI found low to high plasticity fines with varying levels of 

sand and gravel as the dominant lithology of the unconsolidated sediments below the Fargo 

AASF #2. The borings were completed at depths between 6 and 15 feet bgs. Isolated layers of 

well graded gravelly sand were also described in the boring logs at thicknesses ranging from 0.5 

to 1.0 feet. These observations are consistent with the understood depositional environment of 

the region.

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

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

transported via Federal Express (FedEx) under standard chain-of-custody (COC) procedures to 

the laboratory and analyzed for PFAS (LC/MS/MS compliant with QSM Version 5.3 Table B15), total organic carbon (TOC) (EPA Method 9060A), pH (EPA Method 9045D), and grain size 

(ASTM Method D-422) in accordance with the UFP-QAPP Addendum (EA/Wood, 2022). 
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Field duplicate samples were collected at a rate of 10 percent (%) and analyzed for the same 

parameters as the accompanying samples. Matrix spike/matrix spike duplicate (MS/MSD) pairs 

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, one equipment blank (EB) was collected per day and analyzed for 

the same parameters as the soil samples. A temperature blank was placed in each cooler for use 

in confirming that samples were preserved at or below 6 degrees Celsius (°C) during shipment. 

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

sampling and surveying in accordance with the UFP-QAPP Addendum (EA/Wood, 2022). After 

removal of the casings, boreholes were abandoned using bentonite chips. Borings installed in 

asphalt surfaces were restored in accordance with the UFP-QAPP Addendum (EA/Wood, 2022).

5.3 TEMPORARY WELL INSTALLATION AND GROUNDWATER GRAB 

SAMPLING

Temporary wells were installed using a GeoProbe® 66DT dual-tube sampling system. Once the 

borehole was advanced to the desired depth, a temporary well was constructed of a 5-ft section 

of 1-inch Schedule 40 poly-vinyl chloride (PVC) screen with sufficient casing to reach the 

ground surface. New PVC pipe and screen were used at each location to avoid cross

contamination between locations. The screen intervals for the temporary wells are provided in 

Table 5-2.

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

Samples were collected after a period of time following well installation to allow groundwater to 

infiltrate and recharge the temporary well intervals. 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 oxidationreduction potential) were measured using a water quality meter and recorded on the field 

sampling form (Appendix B2) before each grab sample was collected in a separate container. 

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 in laboratory-supplied PFAS-free HDPE bottles and labeled using a 

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

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

with QSM Version 5.3 Table B-15 in accordance with the UFP-QAPP Addendum (EA/Wood, 

2022). 

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

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

parameters as the accompanying samples. One field blank (FB) was collected in accordance with 

the UFP-QAPP Addendum (EA/Wood, 2022). A temperature blank was placed in each cooler 

for use in confirming that samples were preserved at or below 6°C during shipment. 
Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota

EA Engineering, Science, and Technology, Inc., PBC 5-5

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

accordance with the SI UFP-QAPP Addendum (EA/Wood, 2022) by removing the PVC and 

backfilling the hole with bentonite chips. 

5.4 SYNOPTIC WATER LEVEL MEASUREMENTS

A synoptic groundwater gauging event was performed on 11 May 2022. Groundwater elevation 

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

measurements were taken from the survey mark on the northern side of the well casing. The 

synoptic water level measurements from the gauging event indicated a localized groundwater 

flow direction that was generally towards the north. This groundwater flow direction is not 

consistent with the regional groundwater flow direction to the east and is believed to have been 

influenced by heavy precipitation. The regional groundwater flow direction is generally from 

west to east (HMTC 1987; ANG, 2019). The groundwater elevations that were measured during 

the SI are included on the groundwater contour map, Figure 2-5, and groundwater elevation data 

are provided in Table 5-3. 

5.5 SURVEYING

The northern side of each new temporary well casing was surveyed using a Trimble R10 realtime kinematic differential global positioning system. Positions were collected in the applicable 

Universal Transverse Mercator zone projection with World Geodetic System 1984 datum 

(horizontal) and North American Vertical Datum 1988 (vertical). Surveying data were collected 

on 11 May 2022 and are provided in Appendix B3. 

5.6 INVESTIGATION-DERIVED WASTE

As of the date of this report, the disposal of PFAS investigation-derived waste (IDW) is not 

regulated federally. IDW generated during the SI is considered non-hazardous waste and was 

managed in accordance with the UFP-QAPP Addendum (EA/Wood, 2022). 

Soil IDW (i.e., soil cuttings) and liquid IDW (i.e., purge water, development water, and 

decontamination fluids) generated during the SI activities were contained in labeled, 55-gallon 

DOT-approved steel drums, and left onsite in a designated waste storage area. The IDW was not 

sampled and assumes the characteristics of the associated samples collected from that source 

location. The solid and liquid IDW will be disposed of via a Resource Conservation and 

Recovery Act Subtitle C landfill. The disposal is being managed under a separate contract task 

(EA Engineering, Science, and Technology, Inc., 2021). Specifics on the disposal of solid and 

liquid IDW will be addressed in an IDW Technical Memorandum.

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.
Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota

EA Engineering, Science, and Technology, Inc., PBC 5-6

5.7 LABORATORY ANALYTICAL METHODS

Samples were analyzed by LC/MS/MS, compliant with QSM Version 5.3 Table B-15, at

Eurofins in Lancaster, Pennsylvania, a DoD ELAP and NELAP-certified laboratory.

One soil sample was also analyzed for TOC using EPA Method 9060A, pH by EPA Method 

9045D, and grain size using ASTM Method D422.

5.8 DEVIATIONS FROM SI UFP-QAPP ADDENDUM

No deviations from the UFP-QAPP Addendum were identified. 
Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota 

EA Engineering, Science, and Technology, Inc., PBC 5-7 

Table 5-1. Site Inspection Samples by Medium

Fargo AASF #2, Fargo, North Dakota

Site Inspection Report

Sample Identification

Sample 

Collection 

Date

Sample Depth

(ft bgs)

PFAS(LC/MS/MS compliant with QSM 5.3 Table B-15)TOC(EPA Method 9060A)pH (EPA Method 9045D)Grain Size (ASTM D422)

Comments

Soil Samples

AOI01-01-SB-0-2 5/10/2022 0-2 X X X X MS/MSD 

Collected

AOI01-01-SB-4-5 5/10/2022 4-5 X

AOI01-01-SB-9-10 5/10/2022 9-10 X

AOI01-02-SB-0-2 5/10/2022 0-2 X Parent Sample 

of DUP-01-Soil

AOI01-02-SB-2-3 5/10/2022 2-3 X

AOI01-02-SB-3.5-4.5 5/10/2022 3.5-4.5 X

AOI01-03-SB-0-2 5/10/2022 0-2 X

AOI01-03-SB-3-4 5/10/2022 3-4 X

AOI01-03-SB-7-8 5/10/2022 7-8 X

DUP-01-Soil 5/10/2022 X

Groundwater Samples

AASF2-01-GW 5/10/2022 X

AOI01-01-GW 5/10/2022 X

AOI01-02-GW 5/10/2022 X Parent Sample 

of DUP-01-GW

AOI01-03-GW 5/10/2022 X MS/MSD 

Collected

AOI01-04-GW 5/10/2022 X

DUP-01-GW 5/10/2022 X

Blank Samples

AASF2-EB-HA 5/10/2022 X Equipment 

Blank collected 

From Hand 

Auger

AASF2-FB-01 5/10/2022 X Field Blank

Notes:

AASF = Army Aviation Support Facility

ASTM = American Society for Testing and Materials

bgs = below ground surface

EB = equipment blank

FD = field duplicate

FB = field blank

MS/MSD = matrix spike/ matrix spike duplicate

TOC = total organic carbon

EPA = Environmental Protection Agency
Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota 

EA Engineering, Science, and Technology, Inc., PBC 5-8 

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

Fargo AASF #2, Fargo, North Dakota

Site Inspection Report

Area of Interest Boring Location

Soil Boring Depth

(ft bgs)

Temporary Well 

Screen Interval

(ft bgs)

1 

AASF2-01 6 1-6

AOI01-01 15 10-15

AOI01-02 10 5-10

AOI01-03 14 9-14

AOI01-04 12 7-12

Notes:

AASF = Army Aviation Support Facility

bgs = below ground surface

ft = feet
Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota 

EA Engineering, Science, and Technology, Inc., PBC 5-9 

Table 5-3. Groundwater Elevation 

Fargo AASF #2, Fargo, North Dakota

Site Inspection Report

Monitoring Well 

ID

Top of Casing Elevation

(ft NAVD88)

Depth to Water

(ft btoc)

Depth to Water

(ft bgs)

Groundwater Elevation

(ft NAVD 88)

AASF2-01 898.461 4.13 2.11 894.331

AOI01-01 896.41 3.74 3.71 892.67

AOI01-02 896.773 2.38 2.33 894.393

AOI01-03 897.789 3.26 2.50 894.529

AOI01-04 899.771 6.18 3.46 893.591

Notes: 

AASF = Army Aviation Support Facility

bgs = below ground surface

btoc = below top of casing

NAVD88 = North American Vertical Datum 1988
Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota

EA Engineering, Science, and Technology, Inc., PBC 5-10

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Army National Guard Site Inspections

Site Inspection Report

Fargo AASF #2, North Dakota

Figure 5-1

Site Inspection Sample Locations

")

#*

#* #*

")

AOI01-04

AOI01-03 AOI01-02

AOI01-01

AASF2-01

3

Facility Data

Facility Boundary

Area of Interest

Potential PFAS Release

ND ^_

Data Sources: 

ESRI 2020

AECOM 2020

Date:...........................October 2022

Prepared By:............................WSP

Prepared For:........................USACE

Projection:......NAD 1983 StatePlane

G:\ANG\a_MXD\Fargo,ND\SiteInspectionSamples.mxd - megan.cameron - 11/22/2022 - 8:36:50 PM

Facility Boundary

0 150 300 450 75

Feet

AOI

TriMaxTM30

Location

Administrative

Building

Hanger

") Temporary Groundwater Well Location

#*

Soil Boring and Temporary Groundwater

Well Location

Shallow Local Groundwater Flow Direction

from SI

General Regional Groundwater Flow

Direction
Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota

EA Engineering, Science, and Technology, Inc., PBC 5-12

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Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota 

EA Engineering, Science, and Technology, Inc., PBC 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 the AOI is provided in Sections 6.3. SLs 

for relevant compounds, for both soil and groundwater, are presented in Table 6-1. Tables 6-2

through 6-5 present results in soil or groundwater for the relevant compounds. Tables that 

contain all results are provided in Appendix F, and the laboratory reports are provided in 

Appendix G. 

 

6.1 SCREENING LEVELS

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

SLs for soil and groundwater, as described in an OSD memorandum (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 may proceed to the next phase under CERCLA. The SLs 

established in the OSD memorandum apply to the five compounds presented on Table 6-1. 

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

Analyte1,2 

Residential 

(Soil)

(μg/kg)1 

0-2 ft bgs

Industrial / Commercial

Composite Worker 

(Soil)

(μg /kg)1 

2-15 ft bgs

Tap Water

(Groundwater)

(ng/L)1 

PFOA 19 250 6 

PFOS 13 160 4

PFBS 1,900 25,000 601

PFHxS 130 1,600 39

PFNA 19 250 6 

Notes:

1. Assistant Secretary of Defense. July 2022. Risk Based Screening Levels in Groundwater and Soil using 

U.S. Environmental Protection Agency’s (EPA’s) Regional Screening Level Calculator. Hazard Quotient 

(HQ)=0.1. May 2022. 

2. 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.

Abbreviations:

μg/kg = microgram(s) per kilogram

bgs = below ground surface

ft = feet

ng/L = nanogram(s) per liter
Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota

EA Engineering, Science, and Technology, Inc., PBC 6-2

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

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

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

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

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

results (2 to 15 feet bgs). The SLs are not applied to deep subsurface soil results (>15 feet bgs) 

because 15 feet is the anticipated limit of construction activities.

6.2 SOIL PHYSICOCHEMICAL ANALYSES

To provide basic soil parameter information, one soil sample was analyzed for TOC, pH, and 

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

contains the results of the TOC, pH, and grain size sampling. 

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

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

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

lipophobic effects, electrostatic interactions, and interfacial behaviors. At relevant environmental 

pH values, certain PFAS are present as organic anions, and are therefore relatively mobile in 

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

be present in soil or sediment (Higgins and Luthy 2006; Guelfo and Higgins 2013). When 

sufficient organic carbon is present, organic carbon normalized distribution coefficients (Koc 

values) can help in evaluating transport potential, though other geochemical factors (for example, 

pH and presence of polyvalent cations) may also affect PFAS sorption to solid phases

(ITRC, 2018). 

6.3 AOI 1 

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

AOI 1: Hangar. The soil and groundwater results are summarized in Table 6-2 through Table 6-

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

6.3.1 AOI 1 Soil Analytical Results

Soil samples were collected from three boring locations associated with AOI 1 during the SI; 

AOI01-01, AOI01-02, and AOI01-03. Figure 6-1 through Figure 6-5 present the ranges of 

detections in soil. Tables 6-2 and Table 6-4 summarize the soil results.

Surface soil (0 to 2 ft bgs) was sampled from boring locations AOI01-01 through AOI01-03, 

with a duplicate surface soil sample collected at AOI01-02. Soil was also sampled from shallow 

subsurface soil (2 to 5 ft bgs) and deep subsurface soil intervals (3.5 to 10 ft bgs) from boring 

locations AOI01-01 through AOI01-03. 

PFHxS and PFOA were detected in surface soil at concentrations below their respective SLs. 

PFHxS was detected in two of the three surface soil samples (AOI01-01 and AOI01-03) with a 

maximum concentration of 0.56 J μg/kg. PFOA was detected in one of three surface soil 
Site Inspection Report

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EA Engineering, Science, and Technology, Inc., PBC 6-3

locations (AOI01-03) at 0.33 J μg/kg. PFBS and PFNA were not detected in surface soil 

samples. 

PFBS, PFHxS, PFNA, PFOA and PFOS were not detected in shallow or deep subsurface soils. 

6.3.2 AOI 1 Groundwater Analytical Results 

Groundwater samples were collected from five temporary wells associated with AOI 1 during 

the SI (AOI01-01 through AOI01-04 and AASF2-01). Temporary well AASF-02 was installed to 

the west of AOI 1, which was assumed to be upgradient based on the inferred west to east 

regional groundwater flow direction. Synoptic water level measurements taken during the SI 

indicated that the local groundwater flow direction at the Facility appeared to be toward the 

north. This groundwater flow direction is not consistent with the inferred regional groundwater 

flow direction to the east and is believed to have been influenced by heavy precipitation. Based 

on a local groundwater flow direction to the north, all sample locations are cross gradient of AOI 

1. Figures 6-6 and 6-7 presents the ranges of detections in groundwater. Table 6-5 summarizes 

the groundwater results.

Groundwater was sampled from temporary monitoring well locations AOI01-01 through AOI01-

04 and AASF2-01, with a duplicate groundwater sample collected at AOI01-02. PFHxS, PFOA 

and PFOS were detected at concentrations exceeding their respective SLs. PFHxS was detected 

in groundwater at all sample locations at concentrations that ranged from 0.99 J ng/L to 55 ng/L

and exceeded the SL at AOI01-04. PFOA was detected in groundwater at four of the five sample 

locations at concentrations that ranged from 1.5 J ng/L to 11 ng/L and exceeded the SL at 

AOI01-01 and AOI01-02. PFOS was detected in groundwater AOI01-01 at 7.7 ng/L, which

exceeded the SL. PFBS was detected in groundwater at all five sample locations at 

concentrations below the SL that ranged from 1.5 J ng/L to 4.2 ng/L. PFNA was not detected in 

groundwater samples collected from temporary monitoring well locations. 

6.3.3 Conclusions

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

SL at sample locations that were used to assess AOI 1. Relevant compounds were also detected 

in the groundwater sample from temporary well AASF2-01, located west of AOI 1, but at 

concentrations below SLs. The synoptic water level measurements from the SI gauging event 

indicated that localized groundwater flow was generally towards the north. Information provided 

in the ANG 2019 SI Report states that the inferred regional groundwater flow direction is 

generally from west to east (HMTC 1987; ANG, 2019). PFHxS and PFOA were detected in 

surface soil at estimated concentrations well below their respective SLs. The maximum 

concentration detected in surface soil was 0.56 J μg/kg (PFHxS) at AOI01-03. Based on the 

regional groundwater flow and the calculated local groundwater flow direction, detections of 

relevant compounds in AASF2-01, AOI01-02 and AOI01-04 may indicate the presence of offFacility sources. 

There was no evidence of a release within the NDARNG Facility. 
Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota

EA Engineering, Science, and Technology, Inc., PBC 6-4

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Table 6-2

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

Site Inspection Report

 Fargo AASF #2

Analyte OSD Screening Level 1 Result Qual Result Qual 

PFBS 1900 ND U ND U PFHxS 130 0.27 J ND U PFNA 19 ND U ND U PFOA 19 ND U ND U PFOS 13 ND U ND U 

Notes ChemicGray Fill Detected concentrations exceeded OSD Screening Levels PFBS 

PFHxS 

References PFNA 

1. Assistant Secretary of Defense, July 2022. Risk Based Screening Levels Calculated PFOA 

for PFOA, PFOS, PFBS, PFHxS, and PFNA in Groundwater or Soil using USEPA’s PFOS 

Regional Screening Level Calculator. HQ=0.1. May 2022. The screening levels for soil are

based on residential scenario for direct ingestion of contaminated soil.

Interpreted Qualifiers

J = Estimated concentration.U = The analyte was not detected at a level greater than or equal to the adjusted DL.Acronyms and Abbreviationsμg/kg microgram(s) per kilogramAASF Army Aviation Support FacilityAOI Area of InterestDUP duplicateHQ Hazard QuotientID identificationLCMSMS liquid chromatography with tandem mass spectrometryLOD limit of detectionLOQ limit of quantitationND analyte not detected above the LOD (LOD values are presented in Appendix F)OSD Office of the Secretary of the DefenseQSM Quality Systems ManualPFAS per- and polyfluoroalkyl substancesSB soil boringUSEPA United States Environmental Protection AgencyQual interpreted qualifier

Area of Interest A

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

Depth 0 - 2 ft 0 - 2 ft 

Sample Date 5/10/2022 5/10/2022 

Location ID AOI01-01 AOI01-02 

Sample ID AOI01-01-SB-0-2 AOI01-02-SB-0-

EA Engineering, Science, and Technology, Inc., PBC 
Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota

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Table 6-3

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

Site Inspection Report

Fargo AASF #2

Analyte OSD Screening Level 1 Result Qual Result Qual R

PFBS 25000 ND U ND U PFHxS 1600 ND U ND U PFNA 250 ND U ND U PFOA 250 ND U ND U PFOS 160 ND U ND U 

Notes ChGray Fill Detected concentration exceeded OSD Screening Levels PF

PF

References PF

1. Assistant Secretary of Defense, July 2022. Risk Based Screening Levels Calculated PF

for PFOA, PFOS, PFBS, PFHxS, and PFNA in Groundwater or Soil using USEPA’s PF

Regional Screening Level Calculator. HQ=0.1. May 2022. The screening levels for soil arebased on Industrial/Commercial Composite Worker scenario for direct ingestion of contaminated soil.Interpreted Qualifiers

U = The analyte was not detected at a level greater than or equal to the adjusted DL.Acronyms and Abbreviationsμg/kg microgram(s) per kilogramAASF Army Aviation Support FacilityAOI Area of InterestDUP duplicateHQ Hazard QuotientID identificationLCMSMS liquid chromatography with tandem mass spectrometryLOD limit of detectionLOQ limit of quantitationND analyte not detected above the LOD (LOD values are presented in Appendix F)OSD Office of the Secretary of the DefenseQSM Quality Systems ManualPFAS per- and polyfluoroalkyl substancesSB soil boringUSEPA United States Environmental Protection AgencyQual interpreted qualifier

AOI01-01 AOI01-02 

Sample ID AOI01-01-SB-4-5 AOI01-02-SB-2-3 A

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

Area of Interest AOI01

Depth 4 - 5 ft 2 - 3 ft 

Sample Date 5/10/2022 5/10/2022 

Location ID

EA Engineering, Science, and Technology, Inc., PBC 
Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota

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Table 6-4

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

Site Inspection Report

Fargo AASF #2 

Analyte OSD Screening Level 1 Result Qual Result Qual Res

PFBS 25000 ND U ND U NPFHxS 1600 ND U ND U NPFNA 250 ND U ND U NPFOA 250 ND U ND U NPFOS 160 ND U ND U N

Notes Gray Fill Detected concentration exceeded OSD Screening Levels References 

1. 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. The screening levels for soil arebased on Industrial/Commercial Composite Worker scenario for direct ingestion of contaminated soil.Interpreted Qualifiers

U = The analyte was not detected at a level greater than or equal to the adjusted DL.Acronyms and Abbreviationsμg/kg microgram(s) per kilogramAASF Army Aviation Support FacilityAOI Area of InterestDUP duplicateHQ Hazard QuotientID identificationLCMSMS liquid chromatography with tandem mass spectrometryLOD limit of detectionLOQ limit of quantitationND analyte not detected above the LOD (LOD values are presented in Appendix F)OSD Office of the Secretary of the DefenseQSM Quality Systems ManualPFAS per- and polyfluoroalkyl substancesSB soil boringUSEPA United States Environmental Protection AgencyQual interpreted qualifier

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

Area of Interest

Depth

AOI01

9 - 10 ft 3.5 - 4.5 ft 

Location ID AOI01-01 AOI01-02 

Sample ID AOI01-01-SB-9-10AOI01-02-SB-3.5-4.5 AOI

Sample Date 5/10/2022 5/10/2022 

EA Engineering, Science, and Technology, Inc., PBC 
Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota

EA Engineering, Science, and Technology, Inc., PBC 6-10

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Table 6-5

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

Site Inspection Report

Fargo AASF #2

Analyte OSD Screening Level 1 Result Qual Result Qual Result 

PFBS 601 4.2 2.2 2.0 PFHxS 39 15 11 J+ 9.0 PFNA 6 ND U ND UJ ND PFOA 6 11 6.9 J 4.6 PFOS 4 7.7 ND UJ ND 

Notes Gray Fill Detected concentration exceeded OSD Screening Levels 

References 

1. 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 levelsbased on residential scenario for direct ingestion of groundwater.Interpreted Qualifiers

J = Estimated concentration.J+ = The result is an estimated quantity, but the result may be biased high.U = The analyte was not detected at a level greater than or equal to the adjusted DL.UJ = The analyte was not detected at a level greater than or equal to the adjusted DL.  However, the reported adjusted DL is approximate and may be inaccurate or imprecise.Acronyms and AbbreviationsAASF Army Aviation Support FacilityAOI Area of InterestDUP duplicateHQ Hazard QuotientID identificationLCMSMS liquid chromatography with tandem mass spectrometryLOD limit of detectionLOQ limit of quantitationND analyte not detected above the LOD (LOD values are presented in Appendix F)ng/L nanogram(s) per literOSD Office of the Secretary of the DefenseQSM Quality Systems ManualPFAS per- and polyfluoroalkyl substancesSB soil boringUSEPA United States Environmental Protection AgencyQual interpreted qualifier

Sample Date 5/10/2022 5/10/2022 5/10/2

Area of Interest 

Sample Name AOI01-01-GW AOI01-02-GW DUP-0

Location ID AOI01-01 AOI01-02 AOI01-02, 

EA Engineering, Science, and Technology, Inc., PBC 
Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota

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Figure 6-1

PFOS Detections in Soil

!(

!( !(

AOI01-01-SB-0-2

AOI01-02-SB-0-2

AOI01-03-SB-0-2

3

0 150

Feet

Facility Data

Potential PFAS Release

Facility Boundary

Area of Interest

ND

^_

Data Sources: 

ESRI 2020

AECOM 2020

Hydrology

General Regional Groundwater

Flow Direction

Shallow Local Groundwater Flow

Direction from SI

G:\ANG\a_MXD\Fargo,ND\Analytical Figures\PFOS Detections in Soil.mxd - megan.cameron - 11/23/2022 - 11:24:10 AM

Army National Guard Site Inspections

Site Inspection Report

Fargo AASF #2, North Dakota

Date:........................October 2022

Prepared By:..........................WSP

Prepared For:.....................USACE

Projection:......NAD 83 State Plane

Shallow (0-2')

!(

!( !(

AOI01-01-SB-4-5

AOI01-02-SB-2-3

AOI01-03-SB-3-4

3

0 150

Feet

Intermediate (2-5')

!(

!( !(

AOI01-01-SB-9-10

AOI01-02-SB-3.5-4.5 AOI01-03-SB-7-8

3

0 150

Feet

Deep (3.5-10')

NOTES:

PFAS = per- and polyfluoroalkyl substances

PFOS = perfluorooctanesulfonic acid

ND = Non-Detect

(μg/Kg) = Microgram(s) per Kilogram

Exceedances of the OSD SL are depicted 

with a yellow halo.

PFOS Results

(μg/Kg)

!( ND

!( >ND - 13

!!( >13 - 160

!!( >160 - 1,600

!!( >1,600
Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota

EA Engineering, Science, and Technology, Inc., PBC 6-14

This page intentionally left blank
Figure 6-2

PFOA Detections in Soil

!(

!( !(

AOI01-01-SB-0-2

AOI01-02-SB-0-2 AOI01-03-SB-0-2

3

0 150

Feet

Facility Data

Potential PFAS Release

Facility Boundary

Area of Interest

ND

^_

Data Sources: 

ESRI 2020

AECOM 2020

Hydrology

General Regional Groundwater

Flow Direction

Shallow Local Groundwater Flow

Direction from SI

G:\ANG\a_MXD\Fargo,ND\Analytical Figures\PFOA Detections in Soil.mxd - megan.cameron - 11/23/2022 - 11:07:11 AM

Army National Guard Site Inspections

Site Inspection Report

Fargo AASF #2, North Dakota

Date:........................October 2022

Prepared By:.........................WSP

Prepared For:.....................USACE

Projection:......NAD 83 State Plane

Shallow (0-2')

!(

!( !(

AOI01-01-SB-4-5

AOI01-02-SB-2-3 AOI01-03-SB-3-4

3

0 150

Feet

Intermediate (2-5')

!(

!( !(

AOI01-01-SB-9-10

AOI01-02-SB-3.5-4.5 AOI01-03-SB-7-8

3

0 150

Feet

Deep (3.5-10')

NOTES:

PFAS = per- and polyfluoroalkyl substances

PFOA = perfluorooctanoic acid

ND = Non-Detect

(μg/Kg) = Microgram(s) per Kilogram

Exceedances of the OSD SL are depicted 

with a yellow halo.

PFOA Results

(μg/Kg)

!( ND

!( >ND - 19

!!( >19 - 250

!!( >250 - 2,500

!!( >2,500
Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota

EA Engineering, Science, and Technology, Inc., PBC 6-16

This page intentionally left blank
Figure 6-3

PFBS Detections in Soil

!(

!( !(

AOI01-01-SB-0-2

AOI01-02-SB-0-2 AOI01-03-SB-0-2

3

0 150

Feet

Facility Data

Potential PFAS Release

Facility Boundary

Area of Interest

ND

^_

Data Sources: 

ESRI 2020

AECOM 2020

Hydrology

General Regional Groundwater

Flow Direction

Shallow Local Groundwater Flow

Direction from SI

G:\ANG\a_MXD\Fargo,ND\Analytical Figures\PFBS Detections in Soil.mxd - megan.cameron - 11/23/2022 - 10:14:36 AM

Army National Guard Site Inspections

Site Inspection Report

Fargo AASF #2, North Dakota

Date:........................October 2022

Prepared By:.........................WSP

Prepared For:.....................USACE

Projection:......NAD 83 State Plane

Shallow (0-2')

!(

!( !(

AOI01-01-SB-4-5

AOI01-02-SB-2-3 AOI01-03-SB-3-4

3

0 150

Feet

Intermediate (2-5')

!(

!( !(

AOI01-01-SB-9-10

AOI01-02-SB-3.5-4.5 AOI01-03-SB-7-8

3

0 150

Feet

Deep (3.5-10')

NOTES:

PFAS = per- and polyfluoroalkyl substances

PFBS =perfluorobutanesulfonic acid

ND = Non-Detect

(μg/Kg) = Microgram(s) per Kilogram

Exceedances of the OSD SL are depicted 

with a yellow halo.

PFBS Results (μg/Kg)

!( ND

!( >ND - 10

!( >10 - 1,900

!!( >1,900 - 25,000

!!( >25,000
Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota

EA Engineering, Science, and Technology, Inc., PBC 6-18

This page intentionally left blank
Figure 6-4

PFHxS Detections in Soil

!(

!( !(

!(

!(

AOI01-01-SB-0-2

AOI01-02-SB-0-2 AOI01-03-SB-0-2

3

0 150

Feet

Facility Data

Potential PFAS Release

Facility Boundary

Area of Interest

ND

^_

Data Sources: 

ESRI 2020

AECOM 2020

Hydrology

General Regional Groundwater

Flow Direction

Shallow Local Groundwater Flow

Direction from SI

G:\ANG\a_MXD\Fargo,ND\Analytical Figures\PFHxS Detections in Soil.mxd - megan.cameron - 11/23/2022 - 12:14:42 PM

Army National Guard Site Inspections

Site Inspection Report

Fargo AASF #2, North Dakota

Date:........................October 2022

Prepared By:.........................WSP

Prepared For:.....................USACE

Projection:......NAD 83 State Plane

Shallow (0-2')

!(

!( !(

AOI01-01-SB-4-5

AOI01-02-SB-2-3 AOI01-03-SB-3-4

3

0 150

Feet

Intermediate (2-5')

!(

!( !(

AOI01-01-SB-9-10

AOI01-02-SB-3.5-4.5 AOI01-03-SB-7-8

3

0 150

Feet

Deep (3.5-10')

NOTES:

PFAS = per- and polyfluoroalkyl substances

PFHxS =perfluorohexanesulfonic acid

ND = Non-Detect

(μg/Kg) = Microgram(s) per Kilogram

Exceedances of the OSD SL are depicted 

with a yellow halo.

PFHxS Results

(μg/Kg)

!( ND

!( >ND - 10

!!( >10 - 130

!!( >130 - 1,600

!!( >1,600
Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota

EA Engineering, Science, and Technology, Inc., PBC 6-20

This page intentionally left blank
Figure 6-5

PFNA Detections in Soil

!(

!( !(

AOI01-01-SB-0-2

AOI01-02-SB-0-2 AOI01-03-SB-0-2

3

0 150

Feet

Facility Data

Potential PFAS Release

Facility Boundary

Area of Interest

ND

^_

Data Sources: 

ESRI 2020

AECOM 2020

Hydrology

General Regional Groundwater

Flow Direction

Shallow Local Groundwater

Flow Direction from SI

G:\ANG\a_MXD\Fargo,ND\Analytical Figures\PFNA Detections in Soil.mxd - megan.cameron - 11/23/2022 - 11:01:20 AM

Army National Guard Site Inspections

Site Inspection Report

Fargo AASF #2, North Dakota

Date:........................October 2022

Prepared By:.........................WSP

Prepared For:.....................USACE

Projection:......NAD 83 State Plane

Shallow (0-2')

!(

!( !(

AOI01-01-SB-4-5

AOI01-02-SB-2-3 AOI01-03-SB-3-4

3

0 150

Feet

Intermediate (2-5')

!(

!( !(

AOI01-01-SB-9-10

AOI01-02-SB-3.5-4.5 AOI01-03-SB-7-8

3

0 150

Feet

Deep (3.5-10')

NOTES:

PFAS = per- and polyfluoroalkyl substances

PFNA = perfluorononanoic acid

ND = Non-Detect

(μg/Kg) = Microgram(s) per Kilogram

Exceedances of the OSD SL are depicted 

with a yellow halo.

PFNA Results (μg/Kg)

!( ND

!( >ND - 19

!!( >19 - 250

!!( >250 - 2,500

!!( >2,500
Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota

EA Engineering, Science, and Technology, Inc., PBC 6-22

This page intentionally left blank
Figure 6-6

PFOA, PFOS, and PFBS Detections in Groundwater

!(

!( !(

!(

!(

!(

!!(

!!(

!(

AOI01-04

AOI01-02 AOI01-03

AOI01-01

AASF2-01

3

0 150

Feet

Facility Data

Potential PFAS Release

Facility Boundary

Area of Interest

ND

^_

Data Sources: 

ESRI 2020

AECOM 2020

Hydrology

General Regional Groundwater

Flow Direction

Shallow Local Groundwater Flow

Direction from SI

G:\ANG\a_MXD\Fargo,ND\Analytical Figures\PFOS_PFOA_PFBS_Detections _in_GW.mxd - megan.cameron - 11/23/2022 - 12:13:08 PM

Army National Guard Site Inspections

Site Inspection Report

Fargo AASF #2, North Dakota

Date:........................October 2022

Prepared By:..........................WSP

Prepared For:.....................USACE

Projection:......NAD 83 State Plane

PFOA

!(

!( !(

!(

!( !!(

AOI01-04

AOI01-02 AOI01-03

AOI01-01

AASF2-01

3

0 150

Feet

PFOS

!(

!( !(

!(

!(

AOI01-04

AOI01-02 AOI01-03

AOI01-01

AASF2-01

3

0 150

Feet

PFBS

NOTES:

PFAS = per- and polyfluoroalkyl substances

PFOA = perfluorooctanoic acid

PFOS = perfluorooctanesulfonic acid

PFBS =perfluorobutanesulfonic acid

ND = Non-Detect

(ng/L) = nanogram(s) per Liter

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

PFOA Results

(ng/L)

!( ND

!( >ND - 6

!!( >6 - 40

!!( >40 - 70

!!( >70

PFOS Results

(ng/L)

!( ND

!( >ND - 4

!!( >4 - 40

!!( >40 - 70

!!( >70

PFBS Results

(ng/L)

!( ND

!( >ND - 100

!!( >100 - 601

!!( >601 - 1,000

!!( >1,000
Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota

EA Engineering, Science, and Technology, Inc., PBC 6-24

This page intentionally left blank
Figure 6-7

PFHxS and PFNA Detections in Groundwater

!!(

!( !(

!(

!(

AOI01-04

AOI01-02 AOI01-03

AOI01-01 AASF2-01

3

0 150

Feet

Facility Data

Potential PFAS Release

Facility Boundary

Area of Interest

ND

^_

Data Sources: 

ESRI 2020

AECOM 2020

Hydrology

General Regional Groundwater

Flow Direction

Shallow Local Groundwater Flow

Direction from SI

G:\ANG\a_MXD\Fargo,ND\Analytical Figures\PFHxS_PFNA_Detections _in_GW.mxd - megan.cameron - 11/23/2022 - 10:53:08 AM

Army National Guard Site Inspections

Site Inspection Report

Fargo AASF #2, North Dakota

Date:........................October 2022

Prepared By:.........................WSP

Prepared For:.....................USACE

Projection:......NAD 83 State Plane

PFHxS

!(

!( !(

!(

!(

AOI01-04

AOI01-02 AOI01-03

AOI01-01 AASF2-01

3

0 150

Feet

PFNA

NOTES:

PFAS = per- and polyfluoroalkyl substances

PFHxS = perfluorohexanesulfonic acid

PFNA = perfluorononanoic acid

ND = Non-Detect

(ng/L) = nanogram(s) per Liter

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

PFHxS Results

(ng/L)

!( ND

!( >ND - 39

!!( >39 - 100

!!( >100 - 1,000

!!( >1,000

PFNA Results

(ng/L)

!( ND

!( >ND - 6

!!( >6 - 100

!!( >100 - 1,000

!!( >1,000
Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota

EA Engineering, Science, and Technology, Inc., PBC 6-26

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Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota

EA Engineering, Science, and Technology, Inc., PBC 7-1

7. EXPOSURE PATHWAYS

The Conceptual Site Model (CSM) for AOI 1, revised based on the SI findings, is presented on 

Figure 7-1. Please note that while the CSM discussion assists in determining if a receptor may 

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

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

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

respect to known and suspected sources, potential transport mechanisms and migration 

pathways, and potentially exposed human receptors. A human exposure pathway is considered 

potentially complete when the following conditions are present. SLs are presented in Section 6.1 

of this report.

1. Contaminant source

2. Environmental fate and transport

3. Exposure point

4. Exposure route

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 no identified complete 

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 the relevant compounds above the SLs. Areas with an identified potentially 

complete pathway and a complete pathway may warrant further investigation. Although the 

CSMs indicate whether potentially complete exposure pathways may exist, the recommendation 

for future study in a 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 EPA guidance for risk screening (EPA 2001). 

Receptors at the Facility include site workers (e.g., Facility staff and visiting soldiers), 

construction workers, off-site residents, off-site recreational users, and potential trespassers.

7.1 SOIL EXPOSURE PATHWAY

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

between the source and potential receptors at the AOI based on the aforementioned criteria. 
Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota

EA Engineering, Science, and Technology, Inc., PBC 7-2

7.1.1 AOI 1 

AOI 1 is comprised of the Hangar portion of the Facility, which is a portion of a larger complex 

not operated by NDARNG. One Tri-MaxTM 30 fire extinguisher was found in the Hangar during 

the visual site inspection conducted during the PA. PFOA and PFHxS were detected in surface 

soil at concentrations below their respective SLs. PFHxS was detected at two sampling locations 

(AOI01-01 and AOI01-03), PFOA was detected at sampling location AOI01-03. Based on the 

results of the SI, direct contact with surface soil outside of AOI 1 could result in site worker, 

construction worker, and/or trespasser exposure to PFOA and PFHxS via inhalation of dust or 

incidental ingestion of soil particles. Relevant compounds were not detected in the shallow and 

deep subsurface soil samples collected outside of AOI 1; therefore, the subsurface soil exposure 

pathway for construction works is incomplete. The CSM for AOI 1 is presented in Figure 7-1.

7.2 GROUNDWATER EXPOSURE PATHWAY

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

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

criteria. 

7.2.1 AOI 1 

AOI 1 is comprised of the Hangar portion of the Facility, a portion of a larger complex not 

operated by NDARNG. One Tri-MaxTM 30 fire extinguisher was found in the Hangar during the 

visual site inspection conducted during the PA. PFOS, PFOA, and PFHxS were detected in 

groundwater at concentrations that exceeded their respective SLs. PFOS was detected in the 

groundwater at one sample locations (AOI01-01) and exceeded the SL. PFOA was detected in 

groundwater at four sample locations (AOI01-01, AOI01-02 [and its duplicate], AOI01-04 and 

AASF2-01) and exceeded the SL at two locations (AOI01-01 and AOI01-02). PFHxS was 

detected in groundwater at all five sample locations and exceeded the SL at AOI01-04. PFBS 

was detected in groundwater at all five sample locations at concentrations that were below the 

SL. Based on the results of the SI, the exposure pathway via ingestion is potentially complete for 

the construction worker, off-site resident, and site worker. Ground disturbing activities that 

extend to the water table (approximately 2 ft bgs) could result in construction worker exposure to 

relevant compounds via incidental ingestion. As there are domestic wells located downgradient 

of the AOI (based on the calculated local groundwater flow direction), there is potential for 

exposure to the off-site residents using these wells. As shallow groundwater may mix with the 

Red River, which is a known municipal drinking water source for the City of Fargo, there is the 

potential for exposure to users of municipal drinking water, which includes both site workers and 

off-site residents. Additionally, there is the potential for exposure to recreational users of the Red 

River. The CSM for AOI 1 is presented in Figure 7-1.

7.3 SURFACE WATER AND SEDIMENT EXPOSURE PATHWAY

There is no surface water located at the AASF, however, stormwater at the Facility is managed 

via the Hector International Airport’s stormwater system using a series of storm sewers, culverts, 

and ditches that ultimately flow to the Red River, which is located approximately 2 miles east of 

the Facility (ANG, 2019). Stormwater has the potential to transport AFFF or PFAS-impacted 
Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota

EA Engineering, Science, and Technology, Inc., PBC 7-3

soils to water bodies. There are no screening levels for surface water or sediments and the 

information included on the CSM for these pathways is informational only. No surface water or 

sediment samples were collected as part of this SI. 

7.3.1 AOI 1 

There were no documented releases of PFAS to the ground surface outside the Hangar, but 

PFAS-containing fire suppressants were stored at the Facility, and there is a potential for PFAS 

releases inside and immediately surrounding the Hangar. PFAS are considered to be very mobile, 

and when present in soil, may leach into the subsurface or be transported with sediment and may 

ultimately reach offsite water bodies, including the Red River. PFOA and PFHxS were detected 

at the surface soil outside of AOI 1. PFHxS was detected at two soil sampling locations (AOI01-

01 and AOI01-03), PFOA was detected at one location (AOI01-03). Based on the detections of 

relevant compounds in surface soil, the exposure pathway via ingestion is potentially complete 

for the recreational user of the Red River, off-site resident, and site worker. There is the potential 

for exposure to recreational users by incidental ingestion of surface water. As the Red River is a 

known municipal drinking water source for the City of Fargo, there is the potential for exposure 

to users of municipal drinking water, which includes both site workers and off-site residents. The 

CSM for AOI 1 is presented in Figure 7-1.
Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota

EA Engineering, Science, and Technology, Inc., PBC 7-4

This page intentionally left blank
Notes:

1. The resident refers to off-site receptors2. Inhalation of dust for off-site receptors is

likely insignificant.

3. No current active construction at the Facility Figure 7-1

Conceptual Site Model

Fargo AASF #2

RECEPTO

Human Receptors

Current/Future

Site 

Worker

Construction 

Worker3 Resident1,2 

AOI 1 PFAS in Surface Soil

Human 

Activities

Precipitation/

Run-Off

Leaching/

Infiltration

Airborne 

Soil 

Particulate

Surface Soil 

at AOI

Surface 

Water/ 

Sediment

Subsurface 

Soil

Shallow 

Groundwater

Ingestion

Ingestion

Ingestion

Ingestion

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

Fire Extinguisher 

Release

SOURCE

Source Release Mechanism Media

PATHWAY

Transport

and Migration Media Exposure Routes

Inhalation 

of Dust

Site 

Worker

Construction 

Worker3 Resident1,2 

LEGEND

Flow Chart ContinuesFlow Chart StopsIncomplete PathwayPotentially Complete PathwayPotentially Complete Pathway with Exceedance of SL
Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota

EA Engineering, Science, and Technology, Inc., PBC 7-6

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Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota

EA Engineering, Science, and Technology, Inc., PBC 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 at the Facility were conducted from 09 to 11 May 2022. The SI field 

activities included soil and groundwater sampling. Field activities were conducted in accordance 

with the UFP-QAPP Addendum (EA/Wood, 2022).

To fulfill the project DQOs set forth in the approved SI UFP-QAPP Addendum (EA/Wood, 

2022), samples were collected and analyzed for a subset of PFAS by LC/MS/MS compliant with 

QSM 5.3 Table B-15 as follows. 

Nine (9) soil grab samples from three boring locations

Five (5) grab groundwater samples from five temporary well locations

Eight (8) QA/QC samples.

An SI is conducted when the PA determines an AOI exists based on probable use, storage, and/or 

disposal of PFAS-containing materials. The SI includes multi-media sampling at AOIs to 

determine whether or not a release has occurred. The SI may conclude further investigation is 

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

required. Additionally, the CSM was refined to assess whether a potentially complete pathway 

exists between the source and potential receptors for potential exposure at the AOI, which is

described in Section 7.

8.2 OUTCOME

Based on the results of the SI, further evaluation of the contamination of groundwater confirmed 

at the Facility is warranted. However, surface soil data suggests the source(s) of contamination 

is not the result of NDARNG activities at the Facility. Therefore, no further investigation by 

DoD (ARNG G-9) is warranted at this time.

No evidence was found indicating the TriMaxTM fire extinguisher at the Facility has been used 

either inside or outside of the Hangar. Facility personnel were unaware that the TriMaxTM fire 

extinguisher was present inside the Hanger, and interviews of Facility personnel during the PA 

had first-hand knowledge that the TriMaxTM fire extinguisher has not been used by NDARNG 

for training or emergency response throughout the entire period of the Facility lease. 

Several potential adjacent sources are located on the airport. The Hector Field ANG Base, which 

is located northeast of the Facility, has several potential release areas that were investigated as 

part of a 2019 SI. This includes a former fire station that is located approximately 700 ft 

northeast of the Facility. Surface soil samples taken from locations around the former fire station 

had detections of PFOS as high as 1,200 J μg/kg. Groundwater samples collected from locations 
Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota 

EA Engineering, Science, and Technology, Inc., PBC 8-2 

around the former fire station had concentrations of PFHxS as high as 79,000 J ng/L, PFOS as 

high as 58,000 J ng/L, and PFOA as high as 16,000 J ng/L (ANG, 2019). Additionally, AFFF 

use on the Hector Field International Airport is possible.

Sample analytical concentrations collected during the SI at the Facility were compared against 

the project SLs in soil and groundwater, as described in Table 6-1. A summary of the results of 

the SI data relative to SLs is as follows:

At AOI 1:

• PFOS, PFOA, and PFHxS were detected in groundwater in areas intended to assess AOI 

1. PFOS exceeded the SL in groundwater in one of the five temporary wells with a 

maximum concentration of 7.7 ng/L (AOI01-01). PFOA exceeded the SL in groundwater 

in two of the temporary wells with a maximum concentration of 11 ng/L (AOI01-01 and 

AOI01-02). PFHxS exceeded the SL in groundwater in one of the five temporary wells 

with a maximum concentration of 55 ng/L (AOI01-04). PFBS was detected in 

groundwater in five temporary wells but did not exceed the SL. PFNA was not detected 

in groundwater in the temporary wells. 

• PFOA and PFHxS were detected in surface soil at AOI 1 at low concentrations, several 

orders of magnitude below the SLs. No relevant compounds were detected in shallow or 

deep subsurface soil samples.

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, as 

screening values were established after SI planning and execution. However, ARNG will add 

HFPO-DA to the list of constituents sampled during the next phase of CERCLA if warranted. 

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 – 

Adjacent to 

Potential Source 

Area1 

Groundwater –

Adjacent to 

Potential Source 

Area1,2 Future Action

1 Hangar No Further Action

Legend:

 = Detected; exceedance of screening levels

 = Detected; no exceedance of screening levels

 = Not detected

1 All samples collected to assess AOI were collected adjacent to the potential source 

area and were located off-Facility. 

2 Groundwater exceedance not associated with DoD release; no further action by 

ARNG G-9.
Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota

EA Engineering, Science, and Technology, Inc., PBC 8-3

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Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota

EA Engineering, Science, and Technology, Inc., PBC 9-1

9. REFERENCES

AECOM. 2020. Final Preliminary Assessment Report, Fargo Army Aviation Support Facility #2. 

North Dakota. August.

Air National Guard (ANG). 2019. Site Inspection Report for Perfluorooctane Sulfonate and

Perfluorooctanoic Acid at Hector Field Air National Guard Base, Fargo, North Dakota.

November.

Assistant Secretary of Defense. 2022. Investigating Per- and Polyfluoroalkyl Substances within 

the Department of Defense Cleanup Program. United States Department of Defense. 6 

July.

Department of the Army (DA). 2016a. EM-200-1-2, Environmental Quality, Technical Project 

Planning Process. 29 February.

. 2016b. Army Guidance to Address Perfluorooctane Sulfonate (PFOS) and 

Perfluorooctanoic Acid (PFOA) Contamination. August.

. 2018. Army Guidance for Addressing Releases of Per-and Polyfluoroalkyl Substances.

September.

DoD. 2019a. Department of Defense (DoD), Department of Energy (DOE) Consolidated Quality

Systems Manual (QSM) for Environmental Laboratories, Version 5.3. May.

. 2019b. General Data Validation Guidelines. November.

. 2020. Data Validation Guidelines Module 3: Data Validation Procedure for Per- and 

Polyfluoroalkyl Substances Analysis by QSM Table B-15. May.

EA, Engineering, Science, and Technology, PBC (EA). 2020. Final Programmatic Uniform 

Federal Policy Quality Assurance Project Plan, Site Inspections for Per- and 

Polyfluoroalkyl Substances Impacted Sites, ARNG Installations, Nationwide. December.

EA Engineering, Science, and Technology, PBC and Wood Environment & Infrastructure 

Solutions, Inc. (EA/Wood). 2021. Accident Prevention Plan/Site Safety and Health Plan 

Addendum, Site Inspections for Per- and Polyfluoroalkyl Substances Impacted Sites, 

ARNG Installations, Nationwide, Fargo Army Aviation Support Facility #2, Fargo, North 

Dakota. November.

. 2022. Final Site Inspection Uniform Federal Policy Quality Assurance Project Plan 

(UFP-QAPP) Addendum, Fargo Army Aviation Support Facility #2, Rapid City, North 

Dakota, Per- and Polyfluoroalkyl Substances Impacted Sites, ARNG Installations, 

Nationwide. November.
Site Inspection Report

Fargo Army Aviation Support Facility #2, North Dakota

EA Engineering, Science, and Technology, Inc., PBC 9-2

Guelfo, J.L. and C.P. Higgins. 2013. Subsurface transport potential of perfluoroalkyl acids and 

aqueous film-forming foam (AFFF)-impacted sites. Environmental Science and 

Technology 47(9):4164-71. 

Higgins, C.P., and R.G. Luthy. 2006. Sorption of perfluorinated surfactants on sediments. 

Environmental Science and Technology 40 (23): 7251-7256. 

HMTC (Hazardous Materials Technical Center) 1987. Installation Restoration Program 

Preliminary Assessment Records Search, 119th Fighter Interceptor Group, North Dakota 

Air National Guard, Hector Field, Fargo, North Dakota, October.

ITRC. 2018. Environmental Fate and Transport for Per- and Polyfluoroalkyl Substances. 

March. 

National Centers for Environmental Information (NCEI). 2022. Record of Climatological 

Observations, Fargo Hector International Airport, ND. 

https://www.ncei.noaa.gov/access/services/data/v1?dataset=dailysummaries&startDate=2022-05-01&endDate=2022-05-

31&stations=USW00014914&format=pdf (Accessed 24 October 2022). 

North Dakota Environmental Quality. 2021. Aquifers of North Dakota. October. chromeextension://efaidnbmnnnibpcajpcglclefindmkaj/https://deq.nd.gov/publications/WQ/1_G

W/General/AquifersofND.pdf?v=1

Ripley, David. 2000. The Water Resource Characteristics of the West Fargo Aquifer System.

SAIC (Science Applications International Corporation). 2013. Preliminary Assessment/Site 

Investigation for Six Areas of Concern at North Dakota Air National Guard, Fargo, 

North Dakota. November.

The City of Fargo. 2019. Water Treatment. December

United States Geological Survey (USGS). 1949. Geology and Ground-Water Resources of

Parts of Cass and Clay Counties North Dakota and Minnesota. October.

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