FINAL

Site Inspection Report

Army Aviation Support Facility #2

Grand Island, Nebraska

Site Inspections 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
Site Inspection Report

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

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

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

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

2.3 HISTORY OF PFAS USE ....................................................................... 2-4

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

3.1 AOI 1 – HANGAR FIRE SUPPRESSION SYSTEM ............................. 3-1

3.2 AOI 2 – TRI-MAXTM 30 FIRE EXTINGUISHERS ............................... 3-1

3.3 ADJACENT SOURCES .......................................................................... 3-2

3.3.1 Central Nebraska Regional Airport .......................................... 3-2

4. PROJECT DATA QUALITY OBJECTIVES ..................................................... 4-1

4.1 PROBLEM STATEMENT ...................................................................... 4-1

4.2 INFORMATION INPUTS ....................................................................... 4-1

4.3 STUDY BOUNDARIES ......................................................................... 4-1

4.4 ANALYTICAL APPROACH ................................................................. 4-1

4.5 DATA USABILITY ASSESSMENT ...................................................... 4-2

5. SITE INSPECTION ACTIVITIES ...................................................................... 5-3

5.1 PRE-INVESTIGATION ACTIVITIES ................................................... 5-4

5.1.1 Technical Project Planning ....................................................... 5-4
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5.1.2 Utility Clearance .......................................................................5-4

5.1.3 Source Water and PFAS Sampling Equipment Acceptability..5-4

5.2 SOIL BORINGS AND SOIL SAMPLING............................................. 5-5

5.3 TEMPORARY WELL INSTALLATION AND GROUNDWATER 

GRAB SAMPLING................................................................................. 5-6

5.4 SYNOPTIC WATER LEVEL MEASUREMENTS ............................... 5-6

5.5 SURVEYING .......................................................................................... 5-7

5.6 INVESTIGATION-DERIVED WASTE................................................. 5-7

5.7 LABORATORY ANALYTICAL METHODS ....................................... 5-7

5.8 DEVIATIONS FROM UFP-QAPP ADDENDUM................................. 5-7

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

6.1 SCREENING LEVELS ........................................................................... 6-1

6.2 SOIL PHYSICOCHEMICAL ANALYSES............................................ 6-2

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

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

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

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

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

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

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

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

6.5 BOUNDARY SAMPLE LOCATIONS .................................................. 6-4

6.5.1 Boundary Locations – Soil Analytical Results......................... 6-4

6.5.2 Boundary Locations – Groundwater Analytical Results ..........6-4

6.5.3 Boundary Locations – Conclusions..........................................6-4

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

7.1 SOIL EXPOSURE PATHWAY.............................................................. 7-1

7.1.1 AOI 1 ........................................................................................7-2

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

7.2 GROUNDWATER EXPOSURE PATHWAY........................................ 7-2

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

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

8. SUMMARY AND OUTCOME ..........................................................................8-1
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8.1 SITE INSPECTION ACTIVITIES.......................................................... 8-1

8.2 OUTCOME.............................................................................................. 8-1

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. Field Forms 

B3. Survey Data

B4. Field Change Request Form

Appendix C. Technical Project Planning Meeting Minutes

Appendix D. Boring Logs and Well Construction Diagrams

Appendix E. Analytical Results

Appendix F. Laboratory Reports
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LIST OF FIGURES

Figure 2-1. Facility Location

Figure 2-2. Topography

Figure 2-3. Groundwater Features

Figure 2-4. Surface Water Features

Figure 2-5. Groundwater Elevations, December 2021

Figure 3-1. Areas of Interest

Figure 5-1. Site Inspection Sample Locations

Figure 6-1. PFOS Detections in Soil

Figure 6-2. PFOA Detections in Soil

Figure 6-3. PFBS Detections in Soil

Figure 6-4. PFHxS Detections in Soil

Figure 6-5. PFNA Detections in Soil

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

Figure 6-7. PFHxS and PFNA Detections in Groundwater

Figure 7-1. Conceptual Site Model, AOI 1 

Figure 7-2. Conceptual Site Model, AOI 2
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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, Grand Island AASF #2, Grand Island, Nebraska, Site 

Inspection Report

Table 5-2. Soil Boring Depths and Temporary Well Screen Intervals, Grand Island AASF

#2, Grand Island, Nebraska, Site Inspection Report

Table 5-3. Groundwater Elevations, Grand Island AASF #2, Grand Island, Nebraska, 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, Grand Island AASF #2

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

Site Inspection Report, Grand Island AASF #2 

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

Inspection Report, Grand Island AASF #2 

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

Inspection Report, Grand Island 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

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

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

DQO Data quality objective

DUA Data usability assessment

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

EB Equipment blank 

ELAP Environmental Laboratory Accreditation Program

EM Engineer Manual

FB Field blank

FedEx Federal Express

ft Foot (feet)

HDPE High-density polyethylene

HEF High-expansion foam

HFPO-DA Hexafluoropropylene oxide dimer acid

ID Identification

IDW Investigation-derived waste

ITRC Interstate Technology Regulatory Council

Koc Organic carbon normalized distribution coefficient

LC/MS/MS Liquid chromatography with tandem mass spectrometry
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LIST OF ACRONYMS AND ABBREVIATIONS (continued)

MIL-SPEC Military Specification

MS Matrix spike

MSD Matrix spike duplicate

NEARNG Nebraska Army National Guard

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 

SI Site Inspection

SL Screening level

TOC Total organic carbon

TPP Technical Project Planning

UFP Uniform Federal Policy 

USACE U.S. Army Corps of Engineers

USEPA U.S. Environmental Protection Agency
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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 from the Office of the Secretary of Defense (OSD) (Assistant Secretary of 

Defense) 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 two Areas of Interest (AOIs) where PFAS-containing materials may have been 

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

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

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

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

relevant compounds. This SI was completed at the Grand Island Army Aviation Support Facility 

(AASF) #2 located in Grand Island, Nebraska, and it was determined that further evaluation 

under the Comprehensive Environmental Response, Compensation, and Liability Act 

(CERCLA) is warranted for AOI 2 and no further evaluation is warranted for AOI 1 at this time. 

The Grand Island AASF #2 will be referred to as the “Facility” throughout this document. 

The Grand Island AASF #2, is adjacent to the Central Nebraska Regional Airport and accessible 

from East Airport Road. The Facility is operated by the Nebraska ARNG (NEARNG) and 

encompasses approximately 49.5 acres in Hall County, approximately 3 miles northeast of Grand 

Island. The AASF #2 was constructed in 2009 as a NEARNG maintenance support facility, and 

the Readiness Center was added in 2014. The Facility is located in the Platt River Lowlands of 

Nebraska, with the Platte River flowing nearby within 5 miles of the AASF #2 (AECOM 

Technical Services, Inc. [AECOM] 2020). 

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

AOIs were compared to OSD SLs for the relevant compounds. Table ES-2 summarizes the SI 

results for the AOIs. Based on the results of this SI, further evaluation under CERCLA is 

warranted in a Remedial Investigation (RI) for AOI 2; however, no further evaluation is 

warranted for AOI 1 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)

Analyte

Residential

(Soil)

(μg/kg)

1 

0 to 2 ft bgs

Industrial/Commercial

Composite Worker

(Soil)

(μg/kg)

 1 

2 to 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 Calculated for 

Groundwater and Soil using U.S. Environmental Protection Agency’s Regional SL 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.

bgs = Below ground surface

μg/kg = Microgram(s) per kilogram

ng/L = Nanogram(s) per liter

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

AOI Potential Release Area

Soil

Source Area

Groundwater

Source Area

Groundwater

Facility Boundary Future Action

1 Hangar Fire Suppression 

System No Further Action

2 Tri-Max TM 30 Fire 

Extinguishers Proceed to RI

Legend:

 = Detected; exceedance of screening levels.

 = Detected; no exceedance of screening levels.

 = Not detected.
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1. INTRODUCTION

1.1 PROJECT AUTHORIZATION

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

Assessments (PAs) and Site Inspections (SIs) at ARNG facilities nationwide based on the current 

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

compounds presented in the memorandum from the Office of the Secretary of Defense (OSD) 

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

memorandum will be 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)2 at ARNG facilities nationwide. The ARNG 

performed this SI at the Grand Island Army Aviation Support Facility (AASF) #2 located in 

Grand Island, Nebraska. The Grand Island AASF #2 will be referred to as the “Facility” 

throughout this document. 

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; USEPA 1994), and in compliance with U.S. 

Department of the Army (DA) requirements and guidance for field investigations.

1.2 SITE INSPECTION PURPOSE

A PA was performed at the Grand Island AASF #2 (AECOM Technical Services, Inc. [AECOM] 

2020) that identified two Areas of Interest (AOIs) where PFAS-containing materials may have 

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

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

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

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

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 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

Grand Island AASF #2 is in Hall County, approximately 3 miles northeast of Grand Island and 

adjacent to the Central Nebraska Regional Airport (Figure 2-1). The AASF #2 is accessible from 

East Airport Road from the south. The AASF #2 is constructed on a parcel of land that is 

approximately 49.5 acres and has been owned and operated by the State of Nebraska Military 

Department since 2005. Before 2005, the Hall County Airport Authority owned and operated the 

land. In 2009, the AASF #2 was constructed to house the Nebraska ARNG (NEARNG)

maintenance support facility. In 2014, the Grand Island Readiness Center was added to the 

campus. The Readiness Center is used to train part- and full-time soldiers in aviation and skill 

development. Currently, no other new structures have been added to the AASF #2 Facility 

(AECOM 2020).

2.2 FACILITY ENVIRONMENTAL SETTING

The AASF #2 is in the Platte River Lowlands of Nebraska. The Platte River flows within 5 miles

of the AASF #2, which is surrounded by agricultural land, and there are three lakes located 

within 3 miles of the Facility. Lake Davis, Crystal Lake, and Eagles Lake are located to the south 

of the Facility. The elevation of the AASF #2 is approximately 1,860 feet (ft) above mean sea 

level (amsl) (AECOM 2020).

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

current and future land use. The topography at AASF #2 is 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 AASF #2 lies within the High Plains section of the Great Plains Province. The underlying

geological features at the Facility can be defined by four categories. The first 10 ft below the

surface is alluvial silty clay and topsoil. There is also alluvial sands and gravel from the Grand

Island Formation, which have been reported to be approximately 50 to 60 ft thick. A thinner 

layer of low-permeability alluvial silty clay, which is approximately 5 to 15 ft thick, from the 

Fullerton Formation is also located in the area. This clay can also be referred to as “blue clay.” 

The last layer underneath the Facility is the deepest layer and can be found up to 200 ft thick. It 

is an alluvial sand and gravel from the Holdrege Formation (AECOM 2020).

Grand Island’s geology differs from the typical geological sequence of the High Plains, as there

is no Tertiary material present. The geology that underlies the AASF #2 consists of material from 

the Niobrara Formation. This formation consists of argillaceous chalk, limestone, and shale. 

There is also substantial Quaternary mantle present in this area, which consists of sands, silts, 

clays, and alluvium. There appears to be no surficial difference between the areas of the High 

Plains where there is and is not Tertiary material present (AECOM 2020).
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During the SI, the soil underling the Facility was found to be generally composed of organic silt, 

fine to coarse sand, low plasticity silty sand, medium to high plasticity clayey silt, and some 

gravel. The borings were completed at depths ranging from 16 to 24 ft below ground surface 

(bgs). Samples for grain size analyses were collected at two locations (AOI01-02 and AOI02-01) 

and analyzed via American Society for Testing and Materials (ASTM) Method D-422. The 

results indicate that the soil samples are comprised primarily of sand (93 percent [%] to 95%), 

silt and clay (2.5% to 4.5%), and gravel (2.5%). Boring logs are presented in Appendix D and 

grain size results are presented in Appendix E.

2.2.2 Hydrogeology

There are two aquifers and an aquitard located in the area of the Facility: the Fullerton Formation

Aquitard, the Holdrege Formation Aquifer, and the Formation Aquifer. The Grand Island

Formation Aquifer is an unconfined water table aquifer within the alluvial sands and gravels of

the Grand Island Formation. This allows for shallow groundwater under the Facility. The depth 

to water ranges from 10 to 16 ft below ground surface (bgs) with a total thickness of water 

ranging from about 50 to 60 ft. The predominant groundwater flow in the Grand Island 

Formation Aquifer is to the northeast (Figure 2-2). The Holdrege Formation Aquifer is a 

confined aquifer unit within the sands and gravels of the Holdrege Formation. The groundwater 

flow of the Holdrege Formation Aquifer flows to the northeast, which is a similar direction as the 

Grand Island Formation Aquifer. The Fullerton Formation Aquitard is an underlying clay unit 

with low permeability that acts as a barrier to groundwater flow. This aquitard creates a presence 

of head differences between the two aquifers (AECOM 2020).

The Grand Island Formation aquifer supplies most of the water for the region in the form of

irrigation supply and potable water. The City of Grand Island uses 21 wells that lie between two

channels of the Platte River, using three pumps that allow water to be moved from the basins into

town (AECOM 2020).

There are no potable wells located within the boundary of the Facility; however, there are 

domestic wells and several irrigation wells downgradient and side gradient of the AASF #2

(Figure 2-3). There are several additional livestock, irrigation, and commercial/industrial wells 

within a 1-mile radius of the Facility. Drinking water for the AASF #2 is supplied by the City of 

Grand Island, which sources water from groundwater via sand and gravel aquifers that underlies 

the area (AECOM 2020). 

Depths to water in December 2021 ranged from approximately 11 to 19 ft bgs during synoptic 

water level measurements. Total boring completion depths, to accommodate temporary well 

installation, ranged from 16 to 24 ft bgs. Groundwater elevation contours from the SI are 

presented on Figure 2-5. Although the anticipated regional groundwater flow direction is to the 

northeast, the observed groundwater flow direction at Grand Island AASF #2 is primarily to the 

southeast based on calculated groundwater elevations (Figure 2-5).

2.2.3 Hydrology

The AASF #2 is in the Platte River floodplain (Figure 2-3). The primary surface water feature

found south of the Facility is an intermittent tributary of the Warm Slough. The Warm Slough 
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generally flows southwest to northeast and eventually drains into the Platte River approximately 

24 miles from the Facility. Surface water flow direction at the Facility is to the southeast towards 

Warm Slough (AECOM 2020).

The Platte River is classified as the longest braided river in North America. It flows from the

Rocky Mountains in Colorado and Wyoming to the Missouri River, which drains into the

Mississippi River. As a braided river, the Platte River is a network of multiple small shallow

channels that all flow in the same direction. The Platte River is prone to flooding and has

contributed to flooding in Grand Island as recently as 2019 (AECOM 2020).

2.2.4 Climate

The climate at the facility has four defined seasons where the summers are warm and mostly

clear; the winters are freezing, windy, snowy, and typically have a lot of cloud cover.

Temperatures vary from average highs of 62.3 degrees Fahrenheit (°F) to average lows of 

39.2°F. The average annual temperature is 50.75°F. Average precipitation is 26.61 inches of rain

(AECOM 2020).

2.2.5 Current and Future Land Use

The AASF #2 is a fenced, controlled access Facility and is adjacent to Central Nebraska 

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

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

controls are unknown (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 Hall County, Nebraska (U.S. Fish and Wildlife Service 2022):

• Birds: Piping Plover (Charadrius melodus) – Federally Threatened, Whooping Crane 

(Grus americana) – Federally Endangered

• Fishes: Pallid Sturgeon (Scaphirhynchus albus) – Federally Endangered

• Flowering Plants: Western Prairie Fringed Orchid (Platanthera praeclara) – Federally 

Threatened

• Insects: Monarch Butterfly (Danaus plexippus) – Federal Candidate

• Mammal: Northern Long-eared Bat (Myotis septentrionalis) – Federally Threatened
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2.3 HISTORY OF PFAS USE

Two potential PFAS release areas were identified at the Facility during the PA where aqueous 

film-forming foam (AFFF) was stored (AECOM 2020). Interviews and records obtained during 

the PA indicate that AFFF is stored on-site for its use within Tri-MaxTM 30 fire extinguishers. 

Additionally, the hangar fire suppression system, which was installed in 2010, contains highexpansion foam (HEF) concentrate. The hangar fire suppression system was initially tested with 

a full hangar release. According to the PA, one Tri-MaxTM 30 extinguisher is filled with soap and 

water for training purposes and there have been no reports of the extinguishers ever being used 

or dispensed at the facility. A description of each AOI is presented in Section 3. 
Grand Island AASF #2

Central Nebraska

Regional Airport

^_

NE

Facility Data

Facility Boundary

3

0 1

Miles

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

Prepared By:.............................EA

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

Projection:.......WGS 84 UTM 14N

Data Sources:

ESRI 2020

AECOM 2020

Figure 2-1

Facility Location

Army National Guard Site Inspections

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Grand Island AASF #2

Central Nebraska

Regional Airport

^_

NE

Facility Data

Facility Boundary

3

0 1

Miles

Data Sources:

ESRI 2020

AECOM 2020

Figure 2-2

Topography

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

Prepared By:.............................EA

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

Projection:.......WGS 84 UTM 14N
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Platte River

Wood River

Prairie Creek

Warm Slough

Moores Creek

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Facility Data

Facility Boundary

Well Type

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Hydrology/Hydrogeology

Inferred Groundwater Flow Direction

Perennial Creek/Stream

Intermittent Creek/Stream

Waterbody

3

0 1

Miles

Data Sources:

ESRI 2020

AECOM 2020

Figure 2-3

Groundwater Features

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Projection:.......WGS 84 UTM 14N
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Platte River

Wood River

Prairie Creek

Warm Slough

Moores Creek

City of

Abbott-Prairie

CreekWatershed

Guendel

Island-Platte

RiverWatershed

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CreekWatershed

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Facility Boundary

Hydrology

Surface Water Flow Direction

Perennial Creek/Stream

Intermittent Creek/Stream

Waterbody

Watershed Boundary

3

0 1

Miles

Data Sources:

ESRI 2020

AECOM 2020

Figure 2-4

Surface Water Features

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

Projection:.......WGS 84 UTM 14N
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AOI 1

AOI 2

(Fire extinguishers storage)

Cold

Storage

Hangar

Hangar

Non-AFFF FTA

TriMax30

Ramp Area

TriMax30

Ramp Area

AOI01-01

1828.46

AOI01-02

1829.1

AOI02-01

1827.9

AOI02-02

1827.23

AOI02-03

1827.99

AOI02-04

1829.61

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1828.87

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1830.02

1830

1829

1828

^_

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Facility Data

Facility Boundary

Area of Interest

Potential PFAS Release

No Suspected Release

Hydrogeology

Groundwater Flow Direction

Groundwater Elevation

Contour Interval (1 Foot)

Dashed where Inferred

<! Temporary Well Location

3

0 250

Feet

Data Sources:

ESRI 2020

AECOM 2020

Figure 2-5

Groundwater Elevations, December 2021

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

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Projection:.......WGS 84 UTM 14N

Note: Anticipated regional groundwater

flow direction is to the northeast.
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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. Based on the PA findings, two potential release areas were identified at 

Grand Island AASF #2 and grouped into two AOIs. The potential release areas are shown on 

Figure 3-1.

3.1 AOI 1 – HANGAR FIRE SUPPRESSION SYSTEM 

The Hangar Fire Suppression System was installed in 2010 when the hangar was constructed.

The Hangar Fire Suppression system consists of a 250-gallon tank filled with 2 % HEF3

concentrate. After installation in 2010, the fire suppression system was tested with a full hanger 

release. During the fire suppression testing, the hangar doors, which have rubber seals at the 

bottom of the door to prevent leaks, were closed. The HEF was directed to the trench drains in 

the hangar, which drain to an oil/water separator and eventually discharge to the Grand Island 

City Sanitary Wastewater Treatment Plant. The fire suppression system has been serviced 

annually by a contractor, where the system pressure is checked without releasing any of the HEF 

concentrate. The fire suppression system was last serviced in 2017 and is housed in a room with 

no floor drains adjacent to the hanger. During the visual site inspection conducted as part of the 

PA, there was visible corrosion and rust-stained concrete under valves in the fire suppression 

system room. The interviewee indicated this was most likely caused by the valve leaking HEF 

concentrate. Direct interviewee knowledge prior to 2017 is unavailable; therefore, it is unknown 

if the rubber seals at the bottom of the hangar doors leaked during the 2010 fire suppression 

system testing. There is a cold storage hangar located to the north of the main hangar; however, 

it does not contain a fire suppression system (AECOM 2020). Additionally, there is a non-AFFF 

FTA east of the main hangar where training exercises were conducted using ABC handheld fire 

extinguishers and soap/water filled TriMaxTM mobile units. There has been no reported use of 

AFFF during training exercises in this area (AECOM 2020).

3.2 AOI 2 – TRI-MAXTM 30 FIRE EXTINGUISHERS

There are six Tri-MaxTM 30 fire extinguishers filled with AFFF located at the AASF #2. It is

unknown when the fire extinguishers arrived at the Facility. The Tri-MaxTM 30 fire extinguishers

are placed in various locations on the ramp area in front of the two hangars. One Tri-MaxTM

30 extinguisher is filled with soap and water for training purposes. There were two additional 

empty Tri-MaxTM 30 extinguishers found in crates in the cold storage hanger at the Facility that 

were never filled with AFFF. The fire extinguishers were serviced in 2019; the NEARNG sent 

the AFFF-filled Tri-MaxTM 30 fire extinguishers to the Lincoln AASF #2 in Lincoln, Nebraska,

where they could be sent to a contractor to undergo hydrostatic testing. There have been no 

reports or accounts of the Tri-MaxTM 30 extinguishers ever being used or dispensed at the 

Facility (AECOM 2020). 

3 HEF is not expected to be PFAS-containing. In order to be conservative, the area containing this system was 

included in this SI. 
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3.3 ADJACENT SOURCES

One potential off-facility source of PFAS is located adjacent to the Facility and is not under the 

control of the NEARNG. A description of the off-facility source is presented below and shown 

on Figure 3-1. 

3.3.1 Central Nebraska Regional Airport

The Central Nebraska Regional Airport was constructed in 1937 and is owned and operated by 

the Hall County Airport Authority. The Facility is southeast and side- to down-gradient of the 

Central Nebraska Regional Airport. The airport does not have a fire department. There are 

public, corporate, and private aircraft hangars, which could potentially have AFFF fire 

suppression systems. It is unknown whether the adjacent Central Nebraska Regional Airport uses 

AFFF in any capacity (AECOM 2020). 

Based on the synoptic water levels collected during SI field activities (presented in Table 5-3), 

local groundwater flow at the Facility is to the southeast. However, regional groundwater flow is 

reportedly to the northeast (see Section 2.2.2). 
AOI 1

AOI 2

AOI 2

Cold

Storage

Hangar

Hangar

Non-AFFF FTA

Central Nebraska

Regional Airport

TriMax30 Ramp Area

TriMax30 Ramp Area

^_

NE

Facility Data

Facility Boundary

Area of Interest

Potential PFAS Release

No Suspected Release

Hydrogeology

Groundwater Flow Direction

3

0 1,000

Feet

Data Sources:

ESRI 2020

AECOM 2020

Figure 3-1

Areas of Interest

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

Prepared By:.............................EA

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

Projection:.......WGS 84 UTM 14N
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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 2021a), the 

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

identified in the PA. For each AOI, ARNG determines if further investigation is warranted, a 

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

warranted. This SI evaluated groundwater and soil for presence or absence of relevant

compounds at each of the sampled AOIs.

4.1 PROBLEM STATEMENT

ARNG will recommend an AOI for remedial investigation (RI) if site-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 the Grand Island AASF #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 2021a)

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

parameters measured at the time of sampling

4.3 STUDY BOUNDARIES

The scope of the SI was bounded horizontally by the property limits of the Facility (Figure 2-1). 

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

required, the proper stakeholders will be notified, and necessary rights of entry will be obtained 

by ARNG with property owner(s). 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 Lancaster Laboratories Environmental LLC, accredited 

under the Department of Defense (DoD) Environmental Laboratory Accreditation Program 

(ELAP); Accreditation No. 0001.01 and the National Environmental Laboratory Accreditation 

Program (NELAP) (Commonwealth of Pennsylvania Department of Environmental Protection, 

Accreditation No. 36-00037). PFAS data underwent 100 % Stage 2B validation in accordance 

with the DoD General Data Validation Guidelines (2019b) and DoD Data Validation Guidelines 

Module 3: Data Validation Procedure of Per- and Polyfluoroalkyl Substances Analysis by 

Quality Systems Manual (QSM) Table B-15 (2020). PFAS data were compared to applicable 

SLs and decision rules as defined in the UFP-QAPP Addendum (EA 2021a). 
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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, 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 2021a).
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5. SITE INSPECTION ACTIVITIES 

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

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

implemented in accordance with the following approved documents. 

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

Nebraska, dated September 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 2020a)

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

Addendum, Grand Island Army Aviation Support Facility #2, Nebraska, dated October

2021 (EA 2021a)

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

(EA 2020b)

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

Nebraska, dated August 2021 (EA 2021b) 

The SI field activities were conducted on 10 and 15 December 2021 and consisted of direct-push 

technology (DPT) borings, soil sample collection, temporary monitoring well installation, and 

grab groundwater sample collection. Field activities were conducted in accordance with the 

UFP-QAPP Addendum (EA 2021a), except as noted in Section 5.8. Field Change Request 

Forms can be found in Appendix B4.

The following samples were collected during the SI and analyzed for a subset of 24 PFAS via 

Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS) compliant with QSM Version 

5.3 Table B-15 to fulfill the project DQOs:

• Twenty-five (25) soil samples from eight soil boring locations 

• Eight (8) grab groundwater samples from eight temporary well locations

• Five (5) 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. Land survey data is 

provided in Appendix B3. Photographs were not collected during this field effort. 
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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, Engineer Manual (EM) 200-1-2 

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

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

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

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

address the AOIs identified in the PA. 

A combined TPP Meeting 1 and 2 was held on 21 September 2021, prior to SI field activities. 

Meeting minutes are provided in Appendix C. The combined TPP Meeting 1 and 2 was 

conducted in general accordance with EM 200-1-2. The stakeholders for this SI include ARNG 

G9, USACE, NEARNG, and Nebraska Department of Environment and Energy 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 combined TPP Meeting 1 and 2 minutes were memorialized in the 

UFP-QAPP Addendum (EA 2021a). A TPP Meeting 3 will be held to discuss the results of the 

SI. Meeting minutes for TPP 3 will be included in Appendix C of the final report. Future TPP 

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

where warranted.

5.1.2 Utility Clearance

The 811 Nebraska Dig line was contracted to notify them of intrusive work at the Facility. Utility 

clearance was performed at each of the proposed boring locations on 3 December 2021 with 

input from the EA field team. Additionally, the first 5 ft of each boring were pre-cleared by EA’s 

drilling subcontractor, Plains Environmental Services, 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

A sample from a potable water source at EA’s office in Lincoln, Nebraska, was collected on 10 

November 2021, prior to mobilization. Results of the sample confirmed this source to be 

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

Specifically, the sample was analyzed for PFAS by LC/MS/MS compliant with QSM Version 

5.3 Table B-15. These results can be found in Appendix E.

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 2020a). 
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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 2021a). A GeoProbe® 5410 truckmounted setup sampling system was used to collect continuous soil cores to the target depth. 

A hand auger was used to remove soil from the top 5 ft of the boring in compliance with utility 

clearance procedures.

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 boring (AOI01-02) 

included an additional discrete subsurface soil sample (i.e., four total samples from this boring), 

which was inadvertently analyzed for PFAS from the 17–18 ft bgs interval that was sampled for 

geotechnical analyses. 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 (not to exceed 15 ft bgs). Groundwater was encountered at depths ranging from 10 to 18 ft 

bgs during drilling. Total boring completion depths, to accommodate temporary well installation, 

ranged from 16 to 24 ft bgs. 

All soil sample locations are shown on Figure 5-1, and boring sample depths are provided in 

Table 5-1. The soil boring locations were selected based on the AOI information provided in the 

PA (AECOM 2020) and as agreed upon by stakeholders during the TPP and review of the 

UFP-QAPP Addendum (EA 2021a). 

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 D. 

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 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 B-15). One sample per 

AOI was additionally analyzed for total organic compound (TOC) (USEPA Method 9060A), pH 

(USEPA Method 9045D), and grain size (ASTM D422) in accordance with the UFP-QAPP 

Addendum (EA 2021a).

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

the accompanying samples. Matrix spike (MS)/matrix spike duplicates (MSDs) were collected at 

a rate of 5% and analyzed for the same parameters as the accompanying samples. In instances 

when non-dedicated sampling equipment was used, such as a hand auger for the shallow soil 

samples, 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 to ensure that samples were 

preserved at or below 6 degrees Celsius (°C) during shipment. 
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DPT borings were converted to temporary wells, which were subsequently abandoned after 

sampling and surveying in accordance with the UFP-QAPP Addendum (EA 2021a). After 

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

in grass areas to avoid disturbing concrete or asphalt surfaces.

5.3 TEMPORARY WELL INSTALLATION AND GROUNDWATER GRAB 

SAMPLING

Temporary wells were installed using a GeoProbe® 5410 truck-mounted 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 polyvinyl 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, after a period of time following well installation to allow 

groundwater to infiltrate and recharge the temporary well intervals, using a peristaltic pump with 

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

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

determined in the field to reduce turbidity and draw down prior to sampling. Water quality

parameters (e.g., temperature, specific conductance, pH, dissolved oxygen, 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. 

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 2021a). 

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

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

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

the UFP-QAPP Addendum (EA 2021a). A temperature blank was placed in each cooler to ensure 

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

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

accordance with the UFP-QAPP Addendum (EA 2021a) using bentonite chips and surface 

completion material (native topsoil material) at completion of sampling activities.

5.4 SYNOPTIC WATER LEVEL MEASUREMENTS

Groundwater levels were used to monitor facility-wide groundwater elevations and assess 

groundwater flow. Synoptic water level elevation measurements were collected on 15 December 

2021 from the newly installed temporary monitoring wells, taken from the survey mark on the 

northern side of the well casing. Groundwater elevation data are provided in Table 5-3. 
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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 of 1988 (vertical). Surveying data were

collected on 15 December 2021 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. PFAS IDW generated during the SI is considered non-hazardous waste and 

was managed in accordance with the UFP-QAPP Addendum (EA 2021a). 

Soil IDW (i.e., soil cuttings) were left in place at the point of source. The soil cuttings were 

distributed on the downgradient side of the borehole. Liquid IDW (i.e., purge water,

development water, and decontamination fluids) generated during the SI activities were

containerized in a properly labeled 55-gallon drum, which was labeled and secured outside the 

Grand Island NEARNG Armory building (north of building). The liquid IDW container remains 

at the Facility awaiting off-site disposal following USACE and ARNG approval of a Letter Work 

Plan for IDW Disposal. The Letter Work Plan will be submitted for review and approval upon 

issuance of the Draft Final SI Report.

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

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

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

5.7 LABORATORY ANALYTICAL METHODS

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

at Eurofins Lancaster Laboratories Environmental, LLC, in Lancaster, Pennsylvania, a DoD 

ELAP and National Environmental Laboratory Accreditation Program-certified laboratory.

A select number of soil samples were also analyzed for TOC using USEPA Method 9060A, pH 

by USEPA Method 9045D, and grain size by ASTM D422.

5.8 DEVIATIONS FROM UFP-QAPP ADDENDUM

Deviations from the UFP-QAPP Addendum occurred based on field conditions. These deviations 

were discussed between EA, ARNG, and USACE. One deviation from the UFP-QAPP 

Addendum is noted below: 

• AOI01-02: This location was moved to a grassy area on the northeast side of the hangar 

within a preferential drainage pathway resulting from a potential release from the hangar.

This change is noted in the Field Change Request Form provided in Appendix B4.
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Additional deviations occurred that were not documented on a Field Change Request Form. Field 

duplicates for soil samples were collected at a frequency 10% as specified in the UFP-QAPP 

Addendum (EA 2021a); however, one of the duplicate sample containers was broken during 

shipment to the laboratory. Therefore, the actual field duplicate frequency for soil samples was 

7.7%. Additionally, photographs of field activities were not collected during the SI; therefore, 

no photographic log is presented in this SI report. The UFP-QAPP Worksheet 17 indicated that a 

subsample of each groundwater sample would be collected in a separate container and undergo a 

shaker test to identify if there is any foaming. However, the separate containers were shipped to 

the laboratory for prescreening rather than conducting a shaker test in the field. The prescreen 

sample for AOI01-01-GW was inadvertently not provided to the laboratory. 

Table 5-1. 

Samples by Medium

Grand Island AASF #2, Grand Island, Nebraska

Site Inspection Report

Sample 

Identification

Sample 

Collection Date

Sample Depth

(ft bgs)

PFAS(QSM Version 5.3 Table B-15) TOC(USEPA Method 9060A)pH (USEPA Method 9045D)Grain Size (ASTM D422)

Comments

Soil Samples

AOI01-01-SB-0-2 12/10/2021 0-2 X

AOI01-11-SB-0-2 12/10/2021 0-2 X Field duplicate of AOI01-

01-SB-0-2

AOI01-01-SB-8-9 12/10/2021 8-9 X

AOI01-01-SB-17-18 12/10/2021 17-18 X

AOI01-02-SB-0-2 12/10/2021 0-2 X

AOI01-02-SB-6-7 12/10/2021 6-7 X

AOI01-02-SB-14-15 12/10/2021 14-15 X

AOI01-02-SB-17-18 12/10/2021 17-18 X X X X

AOI2-01-SB-0-2 12/10/2021 0-2 X

AOI2-01-SB-6-7 12/10/2021 6-7 X

AOI2-01-SB-14-15 12/10/2021 14-15 X

AOI2-01-SB-17-18 12/10/2021 17-18 X X X Not analyzed for PFAS

AOI2-02-SB-0-2 12/10/2021 0-2 X

AOI2-02-SB-5-6 12/10/2021 5-6 X

AOI2-02-SB-9-10 12/10/2021 9-10 X

AOI2-03-SB-0-2 12/10/2021 0-2 X

AOI2-13-SB-0-2 12/10/2021 0-2 X Field duplicate of AOI2-

03-SB-0-2

AOI2-03-SB-4-5 12/10/2021 4-5 X

AOI2-03-SB-9-10 12/10/2021 9-10 X

AOI2-04-SB-0-2 12/10/2021 0-2 X

AOI2-04-SB-6-7 12/10/2021 6-7 X

AOI2-04-SB-12-13 12/10/2021 12-13 X

GIAASF-01-SB-0-2 12/10/2021 0-2 X
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Sample 

Identification

Sample 

Collection Date

Sample Depth

(ft bgs)

PFAS(QSM Version 5.3 Table B-15) TOC(USEPA Method 9060A)pH (USEPA Method 9045D)Grain Size (ASTM D422)

Comments

GIAASF-12-SB-0-2 12/10/2021 0-2 Not analyzed, no intact 

containers received

GIAASF-01-SB-5-6 12/10/2021 5-6 X

GIAASF-01-SB-9-10 12/10/2021 9-10 X

GIAASF-02-SB-0-2 12/10/2021 0-2 X

GIAASF-02-SB-4-5 12/10/2021 4-5 X

GIAASF-02-SB-9-10 12/10/2021 9-10 X

Groundwater Samples

AOI01-01-GW 12/10/2021 - X

AOI01-02-GW 12/10/2021 - X

AOI2-01-GW 12/10/2021 - X

AOI2-02-GW 12/10/2021 - X

AOI2-03-GW 12/10/2021 - X

AOI2-04-GW 12/10/2021 - X

GIAASF-01-GW 12/10/2021 - X

GIAASF-11-GW 12/10/2021 - X Field duplicate of 

GIAASF-01-GW

GIAASF-02-GW 12/10/2021 - X

Blank Samples/Source Water

GIAASF-FB-12102021 12/10/2021 - X Field Blank

GIAASF-EB-12102021 12/10/2021 - X Equipment Blank

DECON_TEST_111020

21

11/10/2021 - X Source Water

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

Grand Island AASF #2, Grand Island, Nebraska

Site Inspection Report

Area of Interest Boring ID

Soil Boring Depth

(ft bgs)

Temporary Well 

Screen Interval

(ft bgs)

1 AOI01-01 24 18-23

AOI01-02 20 14-19

2 

AOI02-01 20 14-19

AOI02-02 16 9-14

AOI02-03 16 9-14

AOI02-04 20 12-17

Facility Boundary GIAASF-01 16 10-15

GIAASF-02 16 9-14
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Table 5-3. 

Groundwater Elevations 

Grand Island AASF #2, Grand Island, Nebraska

Site Inspection Report

Monitoring Well 

ID

Top of Casing Elevation

(ft amsl)

Depth to Water

(ft btoc)

Depth to Water 

(ft bgs)

Groundwater Elevation

(ft amsl)

AOI01-01 1847.07 18.61 16.57 1828.46

AOI01-02 1846.88 17.78 15.87 1829.10

AOI02-01 1845.80 17.90 16.43 1827.90

AOI02-02 1838.79 11.56 10.34 1827.23

AOI02-03 1839.23 11.24 9.29 1827.99

AOI02-04 1843.91 14.30 12.4 1829.61

GIAASF-01 1840.76 11.89 11.19 1828.87

GIAASF-02 1841.11 11.09 9.65 1830.02

Notes: 

amsl = Above mean sea level

bgs = Below ground surface

btoc = Below top of casing ground

ft = feet

ID = Identification
AOI01-01

AOI01-02

AOI2-01

AOI2-02

AOI2-03

AOI2-04

GIAASF-01

GIAASF-02

AOI 1

AOI 2

(Fire extinguishers storage)

Cold

Storage

Hangar

Hangar

Non-AFFF FTA

TriMax30

Ramp Area

TriMax30

Ramp Area

^_

NE

Facility Data

Facility Boundary

Area of Interest

Potential PFAS Release

No Suspected Release

Sample Locations

DPT

Hydrogeology

Groundwater Flow Direction

3

0 250

Feet

Data Sources:

ESRI 2020

AECOM 2020

Figure 5-1

Site Inspection Sample Locations

Army National Guard Site Inspections

Site Inspection Report

Grand Island AASF #2, Nebraska

Path: G:\Federal\Nationwide\PFAS\MAES_634250383\PROJECTS\SIReport\GrandIsland\GrandIslandSIReport.aprx

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

Prepared By:.............................EA

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

Projection:.......WGS 84 UTM 14N
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6. SITE INSPECTION RESULTS

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

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

Sections 6.3 and 6.4. Tables 6-2 through 6-5 present results for the relevant compounds in soil 

or groundwater. Tables that contain all results are provided in Appendix E, and the laboratory 

reports are provided in Appendix F. 

6.1 SCREENING LEVELS

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

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

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

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

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

CERCLA. The SLs established in the OSD memorandum apply to the five compounds presented 

on Table 6-1. 

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

Analyte

Residential 

(Soil)

(μg/kg)1 

0 to 2 ft bgs

Industrial/Commercial

Composite Worker 

(Soil)

(μg/kg) 1 

2 to 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 

EPA’s Regional Screening Level Calculator. Hazard Quotient=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 HFPODA 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.

μg/kg = Microgram(s) per kilogram

ng/L = Nanogram(s) per liter

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 

ft bgs) and the industrial/commercial worker scenario is applied to shallow and deep subsurface 

soil results (2 to 15 ft bgs). The SLs are not applied to deep subsurface soil results (greater than 

15 ft bgs) because 15 ft is the anticipated limit of construction activities.
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6.2 SOIL PHYSICOCHEMICAL ANALYSES

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

and pH, which are important for evaluating transport through the soil medium. Appendix E

contains the results of the TOC and pH sampling. 

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

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

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

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

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

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

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

and Higgins 2013). When sufficient organic carbon is present, organic carbon normalized 

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

geochemical factors (e.g., pH and presence of polyvalent cations) may also affect PFAS sorption 

to solid phases (ITRC 2018). 

6.3 AOI 1 

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

AOI 1, which includes the Hangar Fire Suppression System equipped with HEF. The detected 

compounds are summarized in Tables 6-2 through 6-5. Soil and groundwater results are 

presented on Figures 6-1 through 6-7.

6.3.1 AOI 1 – Soil Analytical Results

Figures 6-1 through 6-5 present the ranges of detections in soil. Tables 6-2 through 6-4

summarize the soil results. 

Soil was sampled at two boring locations associated with the potential release area at AOI 1. 

Soil was sampled from three intervals at each of the boring locations: surface (0–2 ft bgs), 

shallow subsurface soil (less than 15 ft bgs), and deep subsurface soil (up to 18 ft bgs). One 

boring (AOI01-02) included an additional discrete subsurface soil sample (i.e., four total samples 

from this boring). 

Of the two surface soil samples and five subsurface soil samples collected from AOI 1, none of 

the relevant compounds were detected in surface soil or subsurface soil.

6.3.2 AOI 1 – Groundwater Analytical Results 

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

groundwater results.

Groundwater samples were collected from two temporary wells at AOI 1 during the SI activities. 

PFBS and PFHxS were detected in groundwater at both temporary monitoring well locations 

below the SLs of 601 ng/L and 39 ng/L, respectively. PFBS was detected at concentrations 
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ranging from 1.6 J ng/L to 5.2 ng/L. PFHxS was detected at concentrations ranging from 3.3 

ng/L to 6.2 ng/L. PFOA was detected (3.7 ng/L) in one temporary monitoring well location 

(AOI01-02) below the SL (6 ng/L). PFOS and PFNA were not detected in groundwater at any 

location within AOI 1.

6.3.3 AOI 1 – Conclusions

Based on the results of the SI, none of the relevant compounds were detected soil samples. Three 

relevant compounds (PFBS, PFHxS, and PFOA) were detected in groundwater at the source area 

(AOI 1); however, concentrations did not exceed the associated SLs. Therefore, further 

evaluation of AOI 1 is not warranted.

6.4 AOI 2 

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

AOI 2, which includes storage of six Tri-MaxTM 30 fire extinguishers. The detected compounds 

are summarized in Tables 6-2 through 6-5. Soil and groundwater results are presented on

Figures 6-1 through 6-7.

6.4.1 AOI 2 – Soil Analytical Results

Figures 6-1 through 6-5 present the ranges of detections in soil. Tables 6-2 through 6-4

summarize the soil results. 

Soil was sampled at four boring locations associated with the potential release area at AOI 2. 

Soil was sampled from three intervals at each of the boring locations: surface (0–2 ft bgs), 

shallow subsurface soil (less than 7 ft bgs), and deep subsurface soil (up to 15 ft bgs).

Of the four surface soil samples and eight subsurface soil samples collected from AOI 2, none of 

the relevant compounds were detected in surface soil or subsurface soil.

6.4.2 AOI 2 – Groundwater Analytical Results 

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

groundwater results.

Groundwater samples were collected from four temporary wells at AOI 2 during the SI activities. 

PFHxS and PFOS were detected in one temporary monitoring well at maximum concentrations 

of 130 ng/L and 9 ng/L, respectively, which exceeded the applicable SLs. PFBS was detected in 

groundwater at all temporary monitoring well locations below the SL (601 ng/L). PFOA was 

detected in groundwater at two temporary monitoring well locations (AOI02-03 and AOI02-04)

below the SL (6 ng/L). PFNA was not detected in groundwater at any location within AOI 2.

6.4.3 AOI 2 – Conclusions

Based on the results of the SI, none of the relevant compounds were detected in soil samples. 

Two relevant compounds (PFHxS and PFOS) were detected in groundwater at the source area 
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(AOI 2) at concentrations above their respective SLs. Based on the exceedances of the SLs in 

ground water, further evaluation of AOI 2 is warranted.

6.5 BOUNDARY SAMPLE LOCATIONS

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

samples collected at facility boundary. The detected compounds are summarized in Tables 6-2

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

6.5.1 Boundary Locations – Soil Analytical Results

Figures 6-1 through 6-5 present the ranges of detections in soil. Tables 6-2 and 6-4 summarize 

the soil results. 

Soil boundary sample locations were comprised of two boring locations (GIAASF-01 and 

GIAASF-02) along the facility boundary. Boring location GIAASF-01 was along the 

western/side gradient boundary of the facility. Boring location GIAASF-02 was along the 

northern/upgradient boundary of the facility. Soil was sampled from three intervals in the three 

borings; surface (0–2ft bgs), shallow subsurface soil (less than 6 ft bgs), and deep subsurface soil 

(less than 10 ft bgs). 

Of the two surface soil samples and four subsurface soil samples collected from the Facility 

boundary, none of the relevant compounds were detected in surface soil or subsurface soil.

6.5.2 Boundary Locations – Groundwater Analytical Results 

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

the groundwater results.

Groundwater samples were collected from two temporary well locations along the western/side 

gradient and northern/upgradient boundaries of the Facility. PFOS (5.5 ng/L) was detected in 

groundwater at the northern/upgradient temporary monitoring (GIAASF-02) well location above 

the SL of 4 ng/L. PFBS (maximum concentration of 4.4 ng/L), PFHxS (maximum concentration 

of 12 ng/L), and PFOA (maximum concentration of 3.5 ng/L) were detected in groundwater at 

both boundary temporary monitoring well locations below the applicable SLs. The observed 

PFBS, PFHxS, and PFOA concentrations were higher at GIAASF-01 as compared to GIAASF02. PFNA (maximum concentration of 0.7 J ng/L) was detected in groundwater at GIAASF-02 

below the SL. PFNA was not detected in groundwater at GIAASF-01.

6.5.3 Boundary Locations – Conclusions

Based on the results of the SI, none of the relevant compounds were detected soil samples. One 

relevant compound (PFOS) was detected in groundwater along the northern/upgradient Facility 

boundary at concentrations above the associated SL Therefore, further evaluation of the Facility 

boundary area is needed to determine contribution from potential upgradient sources.
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Analyte Screening Level1,2 Unit Result Qual Result Qual Result Qual Result Qual Result Qual Res

Perfluorobutanesulfonic acid (PFBS) 1,900 μg/kg ND U ND U ND U ND U ND U NPerfluorohexanesulfonic acid (PFHxS) 130 μg/kg ND U ND U ND U ND U ND U NPerfluorononanoic acid (PFNA) 19 μg/kg ND U ND U ND U ND U ND U NPerfluorooctanesulfonic acid (PFOS) 13 μg/kg ND U ND U ND U ND U ND U NPerfluorooctanoic acid (PFOA) 19 μg/kg ND U ND U ND U ND U ND U NNotes:2. The Screening Levels for soil are based on a residential scenario for incidental ingestion of contaminated soil.ND = Analyte not detected above the LOD (LOD values are presented in Appendix F). Qual = Qualifier. U = The analyte was not detected at a level greater than or equal to the adjusted Limit of Detection (LOD). 1. Assistant Secretary of Defense. 2022. Risk-Based Screening Levels in Groundwater and Soil using EPA’s Regional Screening Level Calculator. Hazard Quotient (HQ)=0.1. July 2022. μg/kg = Microgram(s) per kilogram.ft bgs = Feet below ground surface. 

Sample Name AOI01-01-SB-0-2

Sample Date 12/10/2021

PFAS by LC/MS/MS compliant with QSM Version 5.3 Table B-15 (g/kg)

AOI01-11-SB-0-2

Location ID AOI01-01 AOI01-01

AOI01-02-SB-0-2 AOI2-01-SB-0-2

AOI01-02 AOI2-01 AOI2-02

AOI2-02-SB-0-2

12/10/2021

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

0-2

12/10/2021 12/10/2021 12/10/2021

Depth (ft bgs) 0-2 0-2 0-2 0-2

AO

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

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Analyte Screening Level1,2 Unit Result Qual Result Qual Result Qual Result Qual Result Q

Perfluorobutanesulfonic acid (PFBS) 25,000 μg/kg ND U ND U ND U ND U ND U Perfluorohexanesulfonic acid (PFHxS) 1,600 μg/kg ND U ND U ND U ND U ND U Perfluorononanoic acid (PFNA) 250 μg/kg ND U ND U ND U ND U ND U Perfluorooctanesulfonic acid (PFOS) 160 μg/kg ND U ND U ND U ND U ND U Perfluorooctanoic acid (PFOA) 250 μg/kg ND U ND U ND U ND U ND U Notes:ND = Analyte not detected above the LOD (LOD values are presented in Appendix F). Qual = Qualifier. U = The analyte was not detected at a level greater than or equal to the adjusted Limit of Detection (LOD).  μg/kg = Microgram(s) per kilogram.ft bgs = Feet below ground surface. 

Location ID

AOI01-01-SB-8-9

8-9

Sample Name

AOI01-01

PFAS by LC/MS/MS compliant with QSM Version 5.3 Table B-15 (g/kg)1. Assistant Secretary of Defense. 2022. Risk-Based Screening Levels in Groundwater and Soil using EPA’s Regional Screening Level Calculator. Hazard Quotient (HQ)=0.1. July 2022. 2. The Screening Levels for soil are based on incidental ingestion of soil in a industrial/commercial worker scenario. 

Depth (ft bgs) 14-15

Sample Date

Parent Sample ID

AOI01-02 AOI01-02 AOI2-01

AOI01-02-SB-14-15 AOI01-02-SB-6-7 AOI2-01-SB-6-7

AOI2-02 

AOI2-02-SB-5

12/10/2021 12/10/2021 12/10/2021 

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

Site Inspection Report, Grand Island AAFS #2

6-7 6-7 5-6 

12/10/2021 12/10/2021 

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Analyte Screening Level1,2 Unit Result Qual Result Qual Result Qual Result Qual 

Perfluorobutanesulfonic acid (PFBS) 25,000 μg/kg ND U ND U ND U ND U Perfluorohexanesulfonic acid (PFHxS) 1,600 μg/kg ND U ND U ND U ND U Perfluorononanoic acid (PFNA) 250 μg/kg ND U ND U ND U ND U Perfluorooctanesulfonic acid (PFOS) 160 μg/kg ND U ND U ND U ND U Perfluorooctanoic acid (PFOA) 250 μg/kg ND U ND U ND U ND U Notes:ND = Analyte not detected above the LOD (LOD values are presented in Appendix F). Qual = Qualifier. U = The analyte was not detected at a level greater than or equal to the adjusted Limit of Detection (LOD). 

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

Site Inspection Report, Grand Island AAFS #2

12/10/2021 12/10/2021 

AOI01-02 AOI2-01 AOI2-02 

12/10/2021 12/10/2021

AOI01-02-SB-17-18 AOI2-01-SB-14-15 AOI2-02-SB-9-10

ft bgs = Feet below ground surface. 

17-18 14-15 9-10

1. Assistant Secretary of Defense. 2022. Risk-Based Screening Levels in Groundwater and Soil using EPA’s Regional Screening Level Calculator. Hazard Quotient (HQ)=0.1. July 2022. PFAS by LC/MS/MS compliant with QSM Version 5.3 Table B-15 (g/kg)2. The Screening Levels for soil are based on incidental ingestion of soil in a industrial/commercial worker scenario. 

AOI01-01

17-18

AOI01-01-SB-17-18

 μg/kg = Microgram(s) per kilogram.

Location ID

Sample Name

Depth (ft bgs)

Parent Sample ID

Sample Date

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Analyte Screening Level1 Unit Result Qual Result Qual Result Qual Result Qual Res

PFAS by LC/MS/MS compliant with QSM Version 5.3 Table B-15 (ng/L)Perfluorobutanesulfonic acid (PFBS) 601 ng/L 5.2 1.6 J 8 3.2 0.6

Perfluorohexanesulfonic acid (PFHxS) 39 ng/L 6.2 3.3 130 8.5 0.8

Perfluorononanoic acid (PFNA) 6 ng/L ND U ND U ND U ND U ND 

Perfluorooctanesulfonic acid (PFOS) 4 ng/L ND U ND U ND U ND U ND Perfluorooctanoic acid (PFOA) 6 ng/L ND U 3.7 ND U ND U 4.2 

Notes:Values exceeding the Screening Level are shaded gray.ND = Analyte not detected above the LOD (LOD values are presented in Appendix F).  U = The analyte was not detected at a level greater than or equal to the adjusted Limit of Detection (LOD). Qual = Qualifier.J = Estimated concentration.ng/L = Nanogram(s) per liter. 

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

Site Inspection, Grand Island AASF #2 

AOI2-02 A

Sample Date

Parent Sample ID

Sample Name

Location ID 

AOI01-01-GW AOI01-02-GW AOI2-01-GW 

AOI01-01 AOI01-02 AOI2-01

AOI2-02-GW AO

12/10/2021 12/10/2021 12/10/2021 12/10/2021 12

1. Assistant Secretary of Defense. 2022. Risk-Based Screening Levels in Groundwater and Soil using EPA’s Regional Screening Level Calculator. Hazard Quotient (HQ)=0.1. July 2022.

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Figure 6-1

PFOS Detections in Soil

AOI2-04

AOI2-03

AOI2-02

AOI2-01

AOI01-02

AOI01-01

GIAASF-02

GIAASF-01

Hangar

Cold

Storage

Hangar

TriMax30

Ramp Area

TriMax30

Ramp Area

Non-AFFF FTA

AOI 1

AOI 2

AOI 2

(Fire extinguishers storage)

AOI2-04

AOI2-03

AOI2-02

AOI2-01

AOI01-02

AOI01-01

GIAASF-02

GIAASF-01

Hangar

Cold

Storage

Hangar

TriMax30

Ramp Area

TriMax30

Ramp Area

Non-AFFF FTA

AOI 1

AOI 2

AOI 2

(Fire extinguishers storage)

AOI2-04

AOI2-03

AOI2-02

AOI2-01

AOI01-02

AOI01-01

GIAASF-02

GIAASF-01

Hangar

Cold

Storage

Hangar

TriMax30

Ramp Area

TriMax30

Ramp Area

Non-AFFF FTA

AOI 1

AOI 2

AOI 2

(Fire extinguishers storage)

3

0 250

Feet

^_

NE

Data Sources:

ESRI 2022

AECOM 2019

0 250

Feet

0 250

Feet

Shallow Intermediate Deep

Facility Data

Facility Boundary

Area of Interest

Potential PFAS Release

No Suspected Release

Hydrogeology

Groundwater Flow Direction

Notes:

PFOS = Perfluorooctanesulfonic acid

Exceedances of the OSD SL are depicted

with a yellow halo. Depth Intervals shown

represent respective sampling position

within a given soil boring location.

> 1,600

> 160 - 1,600

> 13 - 160

> ND - 13

ND (Non-Detect)

PFOS Results (μg/Kg)

> 1,600

> 160 - 1,600

> 13 - 160

> ND - 13

ND (Non-Detect)

PFOS Results (μg/Kg)

> 1,600

> 130 - 1,600

> 10 - 130

> ND - 10

ND (Non-Detect)

PFOS Results (μg/Kg)

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

Prepared By:.............................EA

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

Projection:........WGS 84 UTM 14N
Site Inspection Report

Grand Island Army Aviation Support Facility #2, Nebraska Version: FINAL

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

This page intentionally left blank
Figure 6-2

PFOA Detections in Soil

AOI2-04

AOI2-03

AOI2-02

AOI2-01

AOI01-02

AOI01-01

GIAASF-02

GIAASF-01

Hangar

Cold

Storage

Hangar

TriMax30

Ramp Area

TriMax30

Ramp Area

Non-AFFF FTA

AOI 1

AOI 2

AOI 2

(Fire extinguishers storage)

AOI2-04

AOI2-03

AOI2-02

AOI2-01

AOI01-02

AOI01-01

GIAASF-02

GIAASF-01

Hangar

Cold

Storage

Hangar

TriMax30

Ramp Area

TriMax30

Ramp Area

Non-AFFF FTA

AOI 1

AOI 2

AOI 2

(Fire extinguishers storage)

AOI2-04

AOI2-03

AOI2-02

AOI2-01

AOI01-02

AOI01-01

GIAASF-02

GIAASF-01

Hangar

Cold

Storage

Hangar

TriMax30

Ramp Area

TriMax30

Ramp Area

Non-AFFF FTA

AOI 1

AOI 2

AOI 2

(Fire extinguishers storage)

3

0 250

Feet

^_

NE

0 250

Feet

0 250

Feet

Shallow Intermediate Deep

Army National Guard Site Inspections

Site Inspection Report

Grand Island AASF #2, Nebraska

Data Sources:

ESRI 2022

AECOM 2019 Notes:

PFOA = Perfluorooctanoic acid

Exceedances of the OSD SL are depicted

with a yellow halo. Depth Intervals shown

represent respective sampling position

within a given soil boring location.

Facility Data

Facility Boundary

Area of Interest

Potential PFAS Release

No Suspected Release

Hydrogeology

Groundwater Flow Direction

> 2,500

> 250 - 2,500

> 19 - 250

> ND - 19

ND (Non-Detect)

PFOA Results (μg/Kg)

> 2,500

> 250- 2,500

> 19 - 250

> ND - 19

ND (Non-Detect)

PFOA Results (μg/Kg)

> 2,500

> 250- 2,500

> 19 - 250

> ND - 19

ND (Non-Detect)

PFOA Results (μg/Kg)

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

Prepared By:.............................EA

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

Projection:........WGS 84 UTM 14N
Site Inspection Report

Grand Island Army Aviation Support Facility #2, Nebraska Version: FINAL

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

This page intentionally left blank
Figure 6-3

PFBS Detections in Soil

AOI2-04

AOI2-03

AOI2-02

AOI2-01

AOI01-02

AOI01-01

GIAASF-02

GIAASF-01

Hangar

Cold

Storage

Hangar

TriMax30

Ramp Area

TriMax30

Ramp Area

Non-AFFF FTA

AOI 1

AOI 2

AOI 2

(Fire extinguishers storage)

AOI2-04

AOI2-03

AOI2-02

AOI2-01

AOI01-02

AOI01-01

GIAASF-02

GIAASF-01

Hangar

Cold

Storage

Hangar

TriMax30

Ramp Area

TriMax30

Ramp Area

Non-AFFF FTA

AOI 1

AOI 2

AOI 2

(Fire extinguishers storage)

AOI2-04

AOI2-03

AOI2-02

AOI2-01

AOI01-02

AOI01-01

GIAASF-02

GIAASF-01

Hangar

Cold

Storage

Hangar

TriMax30

Ramp Area

TriMax30

Ramp Area

Non-AFFF FTA

AOI 1

AOI 2

AOI 2

(Fire extinguishers storage)

3

0 250

Feet

^_

NE

0 250

Feet

0 250

Feet

Shallow Intermediate Deep

Notes:

PFBS = Perfluorobutanesulfonic acid

Exceedances of the OSD SL are depicted

with a yellow halo. Depth Intervals shown

represent respective sampling position

within a given soil boring location.

Army National Guard Site Inspections

Site Inspection Report

Grand Island AASF #2, Nebraska

Data Sources:

ESRI 2022

AECOM 2019

Facility Data

Facility Boundary

Area of Interest

Potential PFAS Release

No Suspected Release

Hydrogeology

Groundwater Flow Direction

> 25,000

> 1,900 - 25,000

> 10 - 1,900

> ND - 10

ND (Non-Detect)

PFBS Results (μg/Kg)

> 25,000

> 1,900 - 25,000

> 10 - 1,900

> ND - 10

ND (Non-Detect)

PFBS Results (μg/Kg)

> 25,000

> 1,900 - 25,000

> 10 - 1,900

> ND - 10

ND (Non-Detect)

PFBS Results (μg/Kg)

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

Prepared By:.............................EA

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

Projection:........WGS 84 UTM 14N
Site Inspection Report

Grand Island Army Aviation Support Facility #2, Nebraska Version: FINAL

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

This page intentionally left blank
Army National Guard Site Inspections

Site Inspection Report

Grand Island AASF #2, Nebraska

Figure 6-4

PFHxS Detections in Soil

AOI2-04

AOI2-03

AOI2-02

AOI2-01

AOI01-02

AOI01-01

GIAASF-02

GIAASF-01

Hangar

Cold

Storage

Hangar

TriMax30

Ramp Area

TriMax30

Ramp Area

Non-AFFF FTA

AOI 1

AOI 2

AOI 2

(Fire extinguishers storage)

AOI2-04

AOI2-03

AOI2-02

AOI2-01

AOI01-02

AOI01-01

GIAASF-02

GIAASF-01

Hangar

Cold

Storage

Hangar

TriMax30

Ramp Area

TriMax30

Ramp Area

Non-AFFF FTA

AOI 1

AOI 2

AOI 2

(Fire extinguishers storage)

AOI2-04

AOI2-03

AOI2-02

AOI2-01

AOI01-02

AOI01-01

GIAASF-02

GIAASF-01

Hangar

Cold

Storage

Hangar

TriMax30

Ramp Area

TriMax30

Ramp Area

Non-AFFF FTA

AOI 1

AOI 2

AOI 2

(Fire extinguishers storage)

3

0 250

Feet

^_

NE

Data Sources:

ESRI 2022

AECOM 2019

0 250

Feet

0 250

Feet

Shallow Intermediate Deep

Facility Data

Facility Boundary

Area of Interest

Potential PFAS Release

No Suspected Release

Hydrogeology

Groundwater Flow Direction

Notes:

PFHxS = Perfluorohexanesulfonic acid

Exceedances of the OSD SL are depicted

with a yellow halo. Depth Intervals shown

represent respective sampling position

within a given soil boring location.

> 1,600

> 130 - 1,600

> 10 - 130

> ND - 10

ND (Non-Detect)

PFHxS Result (μg/Kg)

> 1,600

> 130 - 1,600

> 10 - 130

> ND - 10

ND (Non-Detect)

PFHxS Result (μg/Kg)

> 1,600

> 130 - 1,600

> 10 - 130

> ND - 10

ND (Non-Detect)

PFHxS Result (μg/Kg)

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

Prepared By:.............................EA

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

Projection:........WGS 84 UTM 14N
Site Inspection Report

Grand Island Army Aviation Support Facility #2, Nebraska Version: FINAL

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

This page intentionally left blank
Army National Guard Site Inspections

Site Inspection Report

Grand Island AASF #2, Nebraska

Figure 6-5

PFNA Detections in Soil

AOI2-04

AOI2-03

AOI2-02

AOI2-01

AOI01-02

AOI01-01

GIAASF-02

GIAASF-01

Hangar

Cold

Storage

Hangar

TriMax30

Ramp Area

TriMax30

Ramp Area

Non-AFFF FTA

AOI 1

AOI 2

AOI 2

(Fire extinguishers storage)

AOI2-04

AOI2-03

AOI2-02

AOI2-01

AOI01-02

AOI01-01

GIAASF-02

GIAASF-01

Hangar

Cold

Storage

Hangar

TriMax30

Ramp Area

TriMax30

Ramp Area

Non-AFFF FTA

AOI 1

AOI 2

AOI 2

(Fire extinguishers storage)

AOI2-04

AOI2-03

AOI2-02

AOI2-01

AOI01-02

AOI01-01

GIAASF-02

GIAASF-01

Hangar

Cold

Storage

Hangar

TriMax30

Ramp Area

TriMax30

Ramp Area

Non-AFFF FTA

AOI 1

AOI 2

AOI 2

(Fire extinguishers storage)

3

0 250

Feet

^_

NE

Data Sources:

ESRI 2022

AECOM 2019

0 250

Feet

0 250

Feet

Shallow Intermediate Deep

Facility Data

Facility Boundary

Area of Interest

Potential PFAS Release

No Suspected Release

Hydrogeology

Groundwater Flow Direction

Notes:

PFNA = Perfluorononanoic acid

Exceedances of the OSD SL are depicted

with a yellow halo. Depth Intervals shown

represent respective sampling position

within a given soil boring location.

> 2,500

> 250 - 2,500

> 19 - 250

> ND - 19

ND (Non-Detect)

PFNA Results (μg/Kg)

> 2 ,500

> 250 - 2,500

> 19 - 250

> ND - 19

ND (Non-Detect)

PFNA Results (μg/Kg)

> 2 ,500

> 250 - 2,500

> 19 - 250

> ND - 19

ND (Non-Detect)

PFNA Results (μg/Kg)

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

Prepared By:.............................EA

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

Projection:........WGS 84 UTM 14N
Site Inspection Report

Grand Island Army Aviation Support Facility #2, Nebraska Version: FINAL

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

This page intentionally left blank
Figure 6-6

PFOA, PFOS and PFBS Detections in Groundwater

AOI2-04

AOI2-03

AOI2-02

AOI2-01

AOI01-02

AOI01-01

GIAASF-02

GIAASF-01

Hangar

Cold

Storage

Hangar

TriMax30

Ramp Area

TriMax30

Ramp Area

Non-AFFF FTA

AOI 1

AOI 2

AOI 2

(Fire extinguishers storage)

AOI2-04

AOI2-03

AOI2-02

AOI2-01

AOI01-02

AOI01-01

GIAASF-02

GIAASF-01

Hangar

Cold

Storage

Hangar

TriMax30

Ramp Area

TriMax30

Ramp Area

Non-AFFF FTA

AOI 1

AOI 2

AOI 2

(Fire extinguishers storage)

3

0 250

Feet

^_

NE

0 250

Feet

PFOA PFOS

AOI2-04

AOI2-03

AOI2-02

AOI2-01

AOI01-02

AOI01-01

GIAASF-02

GIAASF-01

Hangar

Cold

Storage

Hangar

TriMax30

Ramp Area

TriMax30

Ramp Area

Non-AFFF FTA

AOI 1

AOI 2

AOI 2

(Fire extinguishers storage)

0 250

Feet

PFBS

Note:

PFOA = Perfluorooctanesulfonic acid

PFOS = Perfluorooctanoic acid

PFBS = Perfluorobutanesulfonic acid

Exceedances of the OSD SL are depicted

with a yellow halo

Army National Guard Site Inspections

Site Inspection Report

Grand Island AASF #2, Nebraska

Data Sources:

ESRI 2022

AECOM 2019

Facility Data

Facility Boundary

Area of Interest

Potential PFAS Release

No Suspected Release

Hydrogeology

Groundwater Flow Direction

> 70

> 40 - 70

> 6 - 40

> ND - 6

ND (Non-Detect)

PFOA Results (ng/L)

> 70

> 40 - 70

> 4 - 40

> ND - 4

ND (Non-Detect)

PFOS Results (ng/L)

> 1,000

> 600 - 1,000

> 100 - 600

> ND - 100

ND (Non-Detect)

PFBS Results (ng/L)

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

Prepared By:.............................EA

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

Projection:........WGS 84 UTM 14N
Site Inspection Report

Grand Island Army Aviation Support Facility #2, Nebraska Version: FINAL

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

This page intentionally left blank
Army National Guard Site Inspections

Site Inspection Report

Grand Island AASF #2, Nebraska

Figure 6-7

PFHxS and PFNA Detections in Groundwater

AOI2-04

AOI2-03

AOI2-02

AOI2-01

AOI01-02

AOI01-01

GIAASF-02

GIAASF-01

Hangar

Cold

Storage

Hangar

TriMax30

Ramp Area

TriMax30

Ramp Area

Non-AFFF FTA

AOI 1

AOI 2

AOI 2

(Fire extinguishers storage)

AOI2-04

AOI2-03

AOI2-02

AOI2-01

AOI01-02

AOI01-01

GIAASF-02

GIAASF-01

Hangar

Cold

Storage

Hangar

TriMax30

Ramp Area

TriMax30

Ramp Area

Non-AFFF FTA

AOI 1

AOI 2

AOI 2

(Fire extinguishers storage)

3

0 300

Feet

Facility Data

Facility Boundary

Area of Interest

Potential PFAS Release

No Suspected Release

Hydrogeology

Groundwater Flow Direction

^_

NE

Data Sources:

ESRI 2020

AECOM 2020

Path: G:\Federal\Nationwide\PFAS\MAES_634250383\PROJECTS\SIReport\GrandIsland\GrandIslandSIReport.aprx

0 300

Feet

PFHxS PFNA

Notes:

PFHxS = Perfluorohexanesulfonic acid

PFNA = Perfluorononanoic acid

Exceedances of the OSD SL are depicted

with a yellow halo.

> 1,000

> 100 - 1,000

> 39 - 100

> ND - 39

ND (Non-Detect)

PFHxS Result (ng/L)

> 1,000

> 100 - 1,000

> 6 - 100

> ND - 6

ND (Non-Detect)

PFNA Results (ng/L)

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

Prepared By:.............................EA

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

Projection:........WGS 84 UTM 14N
Site Inspection Report

Grand Island Army Aviation Support Facility #2, Nebraska Version: FINAL

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

This page intentionally left blank
Site Inspection Report

Grand Island Army Aviation Support Facility #2, Nebraska Version: FINAL

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

7. EXPOSURE PATHWAYS

The conceptual site model (CSM) for each AOI, revised based on the SI findings, are presented 

on Figure 7-1 and 7-2. Please note that while the CSM discussion assists in determining if a 

receptor may be impacted, the decision to move from SI to RI or interim action is determined 

based upon exceedances of the SLs for the relevant compounds and whether the release is more 

than likely attributable to the DoD. A CSM presents the current understanding of the site 

conditions with respect to known and suspected sources, potential transport mechanisms and 

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

considered potentially complete when the following conditions are present:

1. Contaminant source

2. Environmental fate and transport

3. Exposure point

4. Exposure route

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

pathway that have detections of the relevant compounds above the SLs may warrant further 

investigation. Although the CSMs indicate whether potentially complete exposure pathways may 

exist, the recommendation for future study in 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 USEPA guidance for risk screening (USEPA 2001). 

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

construction workers, trespassers (though unlikely due to restricted access), residents outside the 

facility boundary, and recreational users outside of the facility boundary.

7.1 SOIL EXPOSURE PATHWAY 

The SI results for relevant compounds in soil were used to determine whether a potentially 

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

aforementioned criteria. 
Site Inspection Report

Grand Island Army Aviation Support Facility #2, Nebraska Version: FINAL

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

7.1.1 AOI 1 

AOI 1 is the hangar fire suppression system which was tested with a full hanger release. HEF is 

not expected to be PFAS-containing. In order to be conservative, the area containing this system 

was included in the SI.

No relevant compounds were detected in surface or subsurface soil at AOI 1. Therefore, all 

exposure pathways for receptors to surface and subsurface soil are considered incomplete. The 

CSM is presented in Figure 7-1.

7.1.2 AOI 2 

AOI 2 consists of the area where six Tri-MaxTM 30 fire extinguishers filled with AFFF are 

located at the AASF #2 and where releases through training or storage may have occurred. 

No relevant compounds were detected in surface or subsurface soil at AOI 2. Therefore, all 

exposure pathways for receptors to surface and subsurface soil are considered incomplete. The

CSM is presented in Figure 7-2.

7.2 GROUNDWATER EXPOSURE PATHWAY

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

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

7.2.1 AOI 1 

PFBS, PFHxS, and PFOA were detected in groundwater collected from temporary wells

associated with AOI 1; however, no concentrations exceeded their respective SLs. Due to the 

depth to groundwater at AOI 1 (17 to 18 ft bgs), it is unlikely that construction workers would be 

exposed to PFAS through the groundwater via ingestion during trenching activities.

Additionally, there is no active construction underway at the Facility. Therefore, the exposure 

pathway for construction workers via the ingestion of groundwater is considered to be 

incomplete. There are no known potable wells present at the Facility; therefore, the exposure 

pathways for the site workers/trespasser are considered to be incomplete. Downgradient potable 

wells were identified as shown in Figure 2-3. Due to the detections of relevant compounds in 

groundwater which are present below the SLs, the groundwater pathway is considered 

potentially complete to off-facility residents. The CSM is presented in Figure 7-1. 

7.2.2 AOI 2 

PFHxS and PFOS were detected in groundwater above the applicable SLs collected from two

temporary wells associated with AOI 2. PFBS and PFOA were also detected in groundwater 

collected from temporary wells associated with AOI 2; however, concentrations were below the 

applicable SLs. Although there is no active construction underway at the Facility, due to the 

relatively shallow depth to groundwater (11 ft bgs), it is possible that future construction workers 

would be exposed to PFAS in groundwater via ingestion during trenching activities. Therefore, 

the exposure pathway for construction workers via the ingestion of groundwater is considered to 
Site Inspection Report

Grand Island Army Aviation Support Facility #2, Nebraska Version: FINAL

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

be incomplete for current construction workers, but potentially complete with exceedances of SL 

for future construction workers. There are no known potable wells present at the Facility; 

therefore, the exposure pathways for the site workers/trespasser, are considered to be incomplete. 

Downgradient potable wells were identified as shown in Figure 2-3. Due to the detections of 

relevant compounds in groundwater above SLs, the groundwater pathway is considered 

potentially complete to off-facility residents. The CSM is presented in Figure 7-2.

7.3 SURFACE WATER AND SEDIMENT EXPOSURE PATHWAY

No surface water or sediment samples were collected during the SI. However, the SI results in 

soil and groundwater, in combination with knowledge of the fate and transport properties of 

PFAS, were used to determine whether a potentially complete pathway exists between the source 

and potential receptors.

No relevant compounds were detected in surface or subsurface soil samples collected at AOI 1, 

AOI 2, or the Facility Boundary that could potentially be transported to surface water bodies via 

stormwater runoff. Although an intermittent tributary (Warm Slough) is located south of the 

Facility, there are no surface water features located on the Facility. Therefore, the exposure 

pathways for site workers/trespassers, construction workers, off-site residents, and off-site 

recreational users are considered incomplete for both AOI 1 and AOI 2. The CSMs for AOI 1 

and AOI 2 are presented on Figure 7-1 and Figure 7-2, respectively.
Site Inspection Report

Grand Island Army Aviation Support Facility #2, Nebraska Version: FINAL

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

This page intentionally left blank
Notes:

1. The resident and recreational users refer to 

off-site receptors.

Figure 7-1

Conceptual Site Model

AOI 1

RECEPTOR

Human Receptors:

Current/Future

Site 

Worker/ 

Trespasser

Construction 

Worker Resident1 Recreational 

User1

Site 

Worker/ 

Trespasser

Construction 

Worker

Resident1 Recreational 

User1

AOI 1

PFAS in 

Surface and 

Subsurface 

Soil, 

Groundwater

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

Testing of Fire 

Suppression 

System

SOURCE

Source Release 

Mechanism Media

PATHWAY

Transport

and Migration Media Exposure 

Routes

Inhalation 

of Dust

Potentially Complete Pathway with Exceedance of 

Screening Level

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG
Site Inspection Report

Grand Island Army Aviation Support Facility #2, Nebraska Version: FINAL

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

This page intentionally left blank
Notes:

1. No current active construction at the facility.

2. The resident and recreational users refer to offsite receptors.

3. Inhalation of dust for off-site receptors is likely

insignificant. Figure 7-2

Conceptual Site Model

AOI 2

RECEPTOR

Human Receptors:

Current/Future

Site 

Worker/ 

Trespasser

Construction 

Worker1 Resident2,3 Recreational 

User2,3

Site 

Worker/ 

Trespasser

Construction 

Worker

Resident Recreational 

User

AOI 2

PFAS in 

Surface and 

Subsurface 

Soil, 

Groundwater

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 Fire 

Extinguisher 

Testing Using 

AFFF

SOURCE

Source Release 

Mechanism Media

PATHWAY

Transport

and Migration Media Exposure 

Routes

Inhalation 

of Dust

Potentially Complete Pathway with Exceedance of 

Screening Level

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG
Site Inspection Report

Grand Island Army Aviation Support Facility #2, Nebraska Version: FINAL

EA Engineering, Science, and Technology, Inc., PBC 7-8

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Site Inspection Report

Grand Island Army Aviation Support Facility #2, Nebraska Version: FINAL

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 SITE INSPECTION ACTIVITIES 

The SI field activities at the Facility were conducted on 10 and 15 December 2021. The SI field 

activities included 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 2021a), except as previously noted in Section 

5.8.

To fulfill the project DQOs set forth in the approved SI UFP-QAPP Addendum (EA 2021a), 

samples were collected and analyzed for a subset of 24 compounds by LC/MS/MS compliant 

with QSM Version 5.3 Table B-15 as follows:

• Twenty-five (25) soil samples from eight boring locations;

• Eight (8) grab groundwater samples from eight temporary well locations; and

• Five (5) QA/QC samples were collected

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

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

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

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

required. Additionally, the CSMs were refined to assess whether a potentially complete pathway 

exists between the source and potential receptors for potential exposure at the AOIs, which are 

described in Section 7. 

8.2 OUTCOME

Based on the results of this SI, further evaluation under CERCLA is not warranted for AOI 1 at 

this time; however, further evaluation under CERCLA is warranted for AOI 2 (including the 

Facility boundary) (see Table 8-1). Based on the CSMs developed and revised based on the SI 

findings, there is potential for exposure to groundwater at AOI 2 and at the facility boundary 

from sources on the facility resulting from historical DoD activities. Sample chemical analytical 

concentrations collected during this SI were compared against the project SLs for soil and 

groundwater, as described in Table 6-1.

• AOI 1:

 PFBS, PFHxS, and PFOA were detected in groundwater near the source area (AOI 1). 

PFBS and PFHxS were detected below applicable SLs in both of the temporary wells 
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associated with the AOI with maximum concentrations of 5.2 ng/L and 6.2 ng/L, 

respectively. PFOA was detected below the applicable SL in one temporary well 

associated with the AOI with a maximum concentration of 3.7 ng/L. Based on the 

results of the SI, further evaluation of AOI 1 is not warranted in the RI. 

 The relevant compounds were not detected in any of the surface or subsurface soil 

samples collected at AOI 1.

• AOI 2:

 PFBS, PFHxS, PFOS, and PFOA were detected in groundwater near the source area 

at AOI 2. PFHxS and PFOS were detected above applicable SLs (39 ng/L and 4 ng/L, 

respectively) in two of the temporary wells associated with the AOI with maximum 

concentrations of 130 ng/L and 9 ng/L, respectively. PFBS and PFOA were detected 

below the applicable SLs in three of the temporary wells associated with the AOI 

with maximum concentrations of 8 ng/L and 4.2 ng/L, respectively. Based on the 

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

 The relevant compounds were not detected in any of the surface or subsurface soil 

samples collected at AOI 2. 

• The Facility boundary:

 PFBS, PFHxS, PFNA, PFOS, and PFOA were detected in groundwater near the 

Facility boundary and upgradient of the known source areas. PFOS was detected 

above the applicable SL (4 ng/L) in one temporary well associated with the Facility 

boundary with a maximum concentration of 5.5 ng/L. Relevant compounds were 

detected in groundwater upgradient of AOI 1 and AOI 2, which suggests potential 

contributions from off-facility sources. 

 The relevant compounds were not detected in any of the surface or subsurface soil 

samples collected at the Facility boundary. 

Of the six PFAS compounds presented in the 6 July 2022 OSD memorandum, HFPO-DA 

(commonly referred to as GenX) was not included as an analyte at the time of this SI. Based on 

the CSM developed during the PA and revised based on SI findings, the presence of HFPO-DA 

is not anticipated at the facility because HFPO-DA is generally not a component of MIL-SPEC 

AFFF and based on its history including distribution limitations that restricted use of GenX, it is 

generally not a component of other products the military used. In addition, it is unlikely that 

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

Table 8-1 summarizes the SI results for soil and groundwater used to determine if an AOI should 

be considered for further investigation under CERCLA and undergo an RI.
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Table 8-1. Summary of Site Inspection Findings and Recommendations

AOI Potential Release Area

Soil

Source Area

Groundwater

Source Area

Groundwater

Facility Boundary Future Action

1 Hangar Fire Suppression 

System No Further Action

2 Tri-Max TM 30 Fire 

Extinguishers Proceed to RI

Legend:

 = Detected; exceedance of screening levels.

 = Detected; no exceedance of screening levels.

= Not detected.
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