FINAL

Site Inspection Report

Army Aviation Support Facility #1

Lincoln, Nebraska

Site Inspection for Perfluorooctanoic Acid (PFOA), Perfluorooctanesulfonic Acid (PFOS), 

Perfluorohexanesulfonic Acid (PFHxS), Perfluorononanoic Acid (PFNA), Hexafluoropropylene 

oxide dimer acid (HFPO-DA), and Perfluorobutanesulfonic Acid (PFBS)

ARNG Installations, Nationwide

October 2023

Prepared for

Army National Guard Headquarters 

111 S. George Mason Drive 

Arlington, VA 22204

UNCLASSIFIED
Site Inspection Report

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TABLE OF CONTENTS

Page

LIST OF APPENDICES ................................................................................................................ iv

LIST OF FIGURES ........................................................................................................................ v

LIST OF TABLES ......................................................................................................................... vi

LIST OF ACRONYMS AND ABBREVIATIONS ..................................................................... vii

EXECUTIVE SUMMARY ............................................................................................................ 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 .................................................................................................. 2-2

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

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

2.3 HISTORY OF PFAS USE ................................................................................... 2-3

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

3.1 AOI 1 – WEST LAWN FORMER FIRE TRAINING AREA ............................ 3-1

3.2 ADJACENT SOURCES ...................................................................................... 3-1

3.2.1 Lincoln Air National Guard Site ........................................................... 3-1

3.2.1.1 Aircraft Parking Ramp ........................................................ 3-2

3.2.1.2 Fuel Systems Maintenance Hangar ..................................... 3-2

3.2.1.3 Current Fire Station............................................................. 3-2

3.2.1.4 Main Aircraft Maintenance Hangar .................................... 3-2

3.2.1.5 Outfall 001 .......................................................................... 3-2

3.2.1.6 Outfall 002 .......................................................................... 3-3

3.2.1.7 Former Fire Station ............................................................. 3-3

3.2.1.8 Retention Pond .................................................................... 3-3

3.2.1.9 Outfall 003 .......................................................................... 3-3

3.2.1.10 Outfall 004 .......................................................................... 3-3

3.2.1.11 Civil Engineering Building ................................................. 3-3

3.2.1.12 Vehicle Maintenance Building ........................................... 3-4
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3.2.1.13 Outfall 005 ..........................................................................3-4

3.2.2 Former Aircraft Fire Training Area ......................................................3-4

3.2.3 Runway Emergency Response..............................................................3-4

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

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

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

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

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

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

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

5.1 PRE-INVESTIGATION ACTIVITIES............................................................... 5-2

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

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

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

5.2 HAND AUGER SOIL SAMPLING.................................................................... 5-3

5.3 SOIL BORINGS AND SOIL SAMPLING......................................................... 5-3

5.4 TEMPORARY WELL INSTALLATION AND GROUNDWATER GRAB 

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

5.5 EXISTING MONITORING WELL GROUNDWATER SAMPLING .............. 5-5

5.6 SYNOPTIC WATER LEVEL MEASUREMENTS ........................................... 5-5

5.7 SURVEYING ...................................................................................................... 5-5

5.8 INVESTIGATION-DERIVED WASTE............................................................. 5-5

5.9 LABORATORY ANALYTICAL METHODS ................................................... 5-6

5.10 DEVIATIONS FROM UFP-QAPP ADDENDUM............................................. 5-6

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

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

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

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

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

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

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

6.4 BOUNDARY SAMPLE LOCATIONS .............................................................. 6-3

6.4.1 Boundary Locations – Soil Analytical Results.....................................6-3

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

6.4.3 Conclusions...........................................................................................6-4
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7. EXPOSURE PATHWAYS..............................................................................................7-1

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

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

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

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

7.3 SURFACE WATER AND SEDIMENT EXPOSURE PATHWAY................... 7-3

7.3.1 AOI 1 ....................................................................................................7-3

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

8.1 SITE INSPECTION ACTIVITIES...................................................................... 8-1

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

9. REFERENCES ................................................................................................................9-1
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LIST OF APPENDICES

Appendix A. Data Usability Assessment and Data Validation Reports

Appendix B. Field Documentation

B1. Log of Daily Notice of Field Activities

B2. Sampling Forms 

B3. Survey Data

B4. Field Change Request Forms

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 
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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, Lincoln AASF #1, Lincoln, Nebraska, Site Inspection 

Report

Table 5-2. Soil Boring Depths and Temporary Well Screen Intervals, Lincoln AASF #1, 

Lincoln, Nebraska, Site Inspection Report

Table 5-3. Groundwater Elevation, Lincoln AASF #1, Lincoln, 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, Lincoln AASF #1

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

Site Inspection Report, Lincoln AASF #1

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

Inspection Report, Lincoln AASF #1

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

Inspection Report, Lincoln AASF #1

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

ANG Air National Guard

AOI Area of Interest

ARNG Army National Guard

ASTM American Society for Testing and Materials

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

ELAP Environmental Laboratory Accreditation Program

EM Engineer Manual

ft Foot (feet)

FTA Fire Training Area

HA Health Advisory

HDPE High-density polyethylene

HFPO-DA Hexafluoropropylene oxide-dimer acid

IDW Investigation-derived waste

ITRC Interstate Technology Regulatory Council

Koc Organic carbon normalized distribution coefficient

LC/MS/MS Liquid chromatography/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 Perfluorohexane sulfonate

PFNA Perfluorononanoic acid

PFOA Perfluorooctanoic acid

PFOS Perfluorooctanesulfonic acid

PID Photoionization detector

PVC Polyvinyl chloride

QAPP Quality Assurance Project Plan

QA Quality assurance

QC Quality control

QSM Quality Systems Manual

RI Remedial investigation 

RSL Regional Screening Level

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

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

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

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

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

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

(AAFS) #1 in Lincoln, Nebraska, and determined further evaluation under the Comprehensive 

Environmental Response, Compensation, and Liability Act (CERCLA) is warranted for AOI 1. 

Lincoln AAFS#1 will be referred to as the “Facility” throughout this document. 

The Facility, operated by Nebraska ARNG (NEARNG), is in Lancaster County, Lincoln, 

Nebraska, just to the north of Oak Creek. At present, Lincoln AASF #1 is comprised of 

approximately 65.29 acres, and the Facility is constructed on a parcel of land owned by the City 

of Lincoln. The Facility is accessible from the north via Northwest 24th Street and is adjacent to 

the Lincoln Municipal Airport and is located directly south of a parcel of land occupied by the 

Nebraska Air National Guard (NEANG) (AECOM Technical Services, Inc. [AECOM] 2020). 

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

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

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

warranted in a Remedial Investigation (RI) for AOI 1. 

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)

Analyte2

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 West Lawn Former Fire 

Training Area 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 Lincoln Army Aviation Support Facility (AASF) #1 located in Lincoln, 

Nebraska. The Lincoln AASF #1 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 Lincoln AASF #1 (AECOM Technical Services, Inc. [AECOM] 

2020) that identified one Area of Interest (AOI) 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 AOI identified in the PA and determine whether 

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

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

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

The Lincoln AASF #1 is in Lancaster County, Lincoln, Nebraska, just to the north of Oak Creek. 

At present, Lincoln AASF #1 is comprised of approximately 65.29 acres, and the Facility is 

constructed on a parcel of land owned by the City of Lincoln; this parcel was leased in 2006 to 

the State of Nebraska for the use by the NEARNG for an indefinite term. The Facility is 

accessible from the north via Northwest 24th Street and it is adjacent to the Lincoln Municipal 

Airport and located directly south of a parcel of land occupied by the Nebraska Air National 

Guard (NEANG) (Figure 2-1). The Facility is a maintenance and repair facility, and it includes a 

Main Hangar, Cold Storage Building, NEARNG Headquarters building, a parking apron, flight 

ramp, wash rack, fueling point, and taxiway connecting to the airport runway (AECOM 2020).

2.2 FACILITY ENVIRONMENTAL SETTING

The Lincoln AASF #1 is located in Lancaster County which is in the Great Plains of eastern 

Nebraska, a province characterized by a variety of landscapes created by a multitude of 

geological processes. The diversity of the landscape is varied by different subregions created by 

fluvial, eolian, volcanic, or glacial landforms that lead to the creation of the low relief part of 

central North America. The Facility resides in a division of the Great Plains region known as the 

High Plains, which is geographically defined by west to east flowing rivers that cut through 

Tertiary cover (AECOM 2020).

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

current and future land use. The topography at Lincoln AASF #1 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

Lincoln AASF #1 lies within the eastern edge of the Great Plains. In the City of Lincoln, the 

bedrock comes from a Cretaceous-aged sandstone and shale, but in lower primary bedrock, the 

lower Cretaceous Dakota Group includes Lakota Formation and Fusion Shale. The bedrock in 

Nebraska stretches from 350 to 400 feet (ft) and has been covered by an unconsolidated sediment 

from the Quaternary period that is viewed as two lithostratigraphic units. In the upper levels of 

the unconsolidated soil comes 10 to 22 ft of eolian silt and clay deposits. Lower unconsolidated 

units have roughly 15 ft of well-sorted fluvial sand and gravel and can be found thickest in the 

paleostream channels in the underlying Cretaceous bedrock (AECOM 2020).

During the SI, the soil underling the Facility was found to be generally composed of organic silt, 

sandy silt, clayey silt, fine to coarse sand, and some clayey sand. The borings were completed at 

depths ranging from 0 to 21 ft below ground surface (bgs). Samples for grain size analyses were 

collected at one location (AOI01-02) and analyzed via American Society for Testing and 

Materials (ASTM) Method D-422. The results indicate that the soil samples are comprised 
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primarily of silt and clay (99.5 percent [%]) and sand (0.5%). Boring logs are presented in 

Appendix D and grain size results are presented in Appendix E.

2.2.2 Hydrogeology

Two aquifers exist near the Facility, a shallow unconfined aquifer, and a deep confined aquifer.

The shallow aquifer has a depth that extends down to 90 ft bgs and consists of unconsolidated 

sands and clayey soil formed from the Quaternary age. Between the shallow and deep aquifer, 

there is a thick, silty clay layer. This deep aquifer is the principal aquifer of the region and is 

found in the Cretaceous Dakota Formation, which is comprised of fine- to coarse-grained 

sandstone that is poorly consolidated with lenses of shale and Murdock; the deep aquifer begins 

at a depth of 125–150 ft bgs and can be found nearly 350 ft thick (AECOM 2020).

As indicated in the 2019 EDRTM report (EDR 2019), there are several monitoring/observation 

wells located on the facility. There are additional commercial/industrial, irrigation, livestock, 

domestic, other/unknown, and monitoring/observation wells located within a 4-mile radius 

(Figure 2-2). Drinking water for the Facility is supplied by the City of Lincoln Water System, 

which uses nearby river aquifers as its drinking water sources (AECOM 2020).

Depths to water in December 2021 ranged from approximately 5 to 13 ft bgs during synoptic 

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

installation, ranged from 20 to 21 ft bgs. Groundwater elevation contours from the SI are 

presented on Figure 2-5 and indicate the groundwater flow direction at Lincoln AASF #1 is 

primarily to the south based on calculated groundwater elevations (Figure 2-5).

2.2.3 Hydrology

Lincoln AASF #1 is located in the Salt Creek drainage area. Stormwater drains to the north into 

the Old Oak Creek Channel, which eventually discharges to Oak Creek (Figure 2-3). The Old 

Oak Channel was rerouted and is typically empty except during periods of precipitation. Oak 

Creek flows eastward until it conjoins with the Salt Creek, approximately 3 miles east of the 

Facility (AECOM 2020). An additional drainage ditch is present in the southern portion of the 

Facility (i.e., south of AOI 1), which eventually discharges into the Old Oak Creek Channel east 

of the Facility boundary.

2.2.4 Climate

The climate at the Facility has four defined seasons in which summers are warm and humid,

winters are typically dry with light snow, and spring months tend to produce high amounts of

thunderstorms and even tornadoes. Temperatures at the Facility vary from average highs of 

63.1 degrees Fahrenheit (°F) to average lows of 39.9°F. The average annual temperature is 

51.5°F, and the average annual precipitation is 28.94 inches of rain (AECOM 2020).

2.2.5 Current and Future Land Use

The Lincoln AASF #1 is not fenced; it is within a larger fenced area of the controlled access 

facility that includes the ANG Airbase and Lincoln Municipal Airport. Reasonably anticipated 
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future land use is not expected to change from the current land use; however, future 

infrastructure improvements, land acquisitions, and land use controls at the Lincoln Municipal 

Airport and surrounding areas 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 Lancaster 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; Salt Creek Tiger 

Beetle (Cicindela nevadica lincolniana) – Federally Endangered

• Mammal: Northern Long-eared Bat (Myotis septentrionalis) – Federally Threatened.

2.3 HISTORY OF PFAS USE

One potential PFAS release area was identified at the Facility during the PA (AECOM 2020). 

Interviews and records obtained during the PA indicate that fire training exercises occurred on 

the West Lawn where NEARNG dispensed “foam” sometime in the 1990s during familiarization 

training; however, whether the foam released was PFAS-containing was unknown at the time of 

the PA. A description of the AOI is presented in Section 3.
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Figure 2-1

Facility Location

Lincoln

Airport

Lincon AASF #1

3

0 1

Miles

Facility Data

Facility Boundary

ANG Airbase Boundary

^_

NE

Data Sources:

ESRI 2020

AECOM 2020

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

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

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

Projection:........WGS 84 UTM 14N
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Figure 2-2

Topography

Lincoln

Airport

Lincon AASF #1

3

0 1

Miles

Facility Data

Facility Boundary

ANG Airbase Boundary

^_

NE

Data Sources:

ESRI 2020

AECOM 2020

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

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

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

Projection:........WGS 84 UTM 14N
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Figure 2-3

Groundwater Features

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Oak Creek

Olive Branch

Middle Creek

Elk Creek

Haines Branch

Beal Slough

Little Salt Creek

West Oak Creek

Deadmans Run

Salt Lake

3

0 1

Miles

Facility Data

Facility Boundary

ANG Airbase Boundary

Well Type

<! Domestic

<! Irrigation

Hydrology/Hydrogeology

Inferred Groundwater Flow Direction

Intermittent Creek/Stream

Perennial Creek/Stream

Waterbody

^_

NE

Data Sources:

ESRI 2020

AECOM 2020

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

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

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

Projection:........WGS 84 UTM 14N
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Figure 2-4

Surface Water Features

Oak Creek

Elk Creek-Oak Creek Watershed

Middle Creek Watershed

Beal Slough-Salt Creek Watershed

3

0 0.5

Miles

Facility Data

Facility Boundary

ANG Airbase Boundary

Hydrology

Surface Water Flow Direction

Perennial Creek/Stream

Intermittent Creek/Stream

Waterbody

Watershed Boundary

^_

NE

Data Sources:

ESRI 2020

AECOM 2020

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

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

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

Projection:........WGS 84 UTM 14N
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Figure 2-5

Groundwater Elevations, December 2021

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1142

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1147

AOI01-04

1144.63

AOI01-02

1145.89

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1141.33

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1147.02

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1144.54

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1145.81

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AOI 1

Former Aircraft FTA

Retention Pond

Cold Storage

Vehicle Maintenance

- Building 636

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Building 635

West Lawn Former FTA

Outfall 002

Outfall 003

Outfall 001

ABC Extinguisher FTA

Outfall 004

Outfall 005

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Feet

^_

NE

Data Sources:

ESRI 2020

AECOM 2020

Facility Data

Facility Boundary

ANG Airbase Boundary

Area of Interest

Potential PFAS Release

No Suspected Release

Sample Locations

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<! Monitoring Well

Hydrology

Surface Water Flow Direction

Groundwater Flow Direction

Groundwater Contour Interval (1 Foot)

Inferred Groundwater Contour Interval (1 foot)

Perennial Creek/Stream

Waterbody

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

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

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

Projection:........WGS 84 UTM 14N
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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, one potential release area was identified at 

Lincoln AASF #1 and identified as AOI 1. The potential release area is shown on Figure 3-1.

3.1 AOI 1 – WEST LAWN FORMER FIRE TRAINING AREA

The West Lawn Former Fire Training Area (FTA) is located west of the Main Hangar, southwest 

of the Cold Storage Building, and northwest of the ABC Fire Extinguisher FTA; the geographic 

coordinates are 40°50’17.7”N and 96°45’23.1”W. A written statement from a former NEARNG 

employee indicated that fire training exercises occurred on the west lawn, and NEARNG 

dispensed “foam” on the grassy area sometime in the 1990s during familiarization training.

NEARNG personnel, at the time of the PA, could not verify whether the fire training exercises 

were conducted; however, it was believed unlikely that the type of fire extinguishers used during 

the training were aqueous film-forming foam (AFFF) fire extinguishers because Tri-MaxTM 30 

containers, which contain AFFF, were not stored at Lincoln AASF #1 until 2005. In September 

2019, half of the Tri-Max 30TM were emptied and contents were containerized in a 275-gallon 

polyethylene tote in the Cold Storage Building. The emptied Tri-Max 30TM fire extinguishers 

were sent offsite for hydrostatic testing. The 275-gallon tote was disposed by the Defense 

Logistics Agency. Based on the uncertainty of which extinguishers were used during the training

exercises, the West Lawn Former FTA is considered an AOI (AECOM 2020).

3.2 ADJACENT SOURCES

Fifteen potential off-facility sources of PFAS were identified in the PA adjacent to the Facility 

and not under the control of the NEARNG. A description of each off-facility source is presented 

below and shown on Figure 3-1. 

3.2.1 Lincoln Air National Guard Site

The ANG completed an SI at the adjacent Lincoln ANG facility, which is located to the north

generally upgradient of the Facility, to determine where PFAS were used (Leidos 2019). The 

following sections summarize the findings of the SI. All of the adjacent source areas identified in 

the SI are upgradient of AOI 1. During the SI, combined PFOS and PFOA concentrations in 

groundwater were compared to the USEPA Lifetime Health Advisory (HA) (70 nanograms per 

liter [ng/L]) (USEPA 2016a, USEPA 2016b) and PFBS concentrations in groundwater were

compared to the USEPA Regional Screening Level (RSL) for Tap Water (400,000 ng/L)

(USEPA 2018). PFOS, PFOA, and PFBS concentrations in soil were compared to the USEPA 

RSLs (1,260 μg/kg, 1,260 μg/kg, and 1,260,000 μg/kg, respectively) (USEPA 2018). It should 

be noted that there were no soil or groundwater SLs for PFHxS when the previous SI was

conducted at the Lincoln ANG facility. However, PFHxS was detected above the current 

groundwater SL (39 ng/L) in nine upgradient groundwater samples collected during the previous 

SI with a maximum detected concentration of 15,000 ng/L. Therefore, the Lincoln ANG is a 

potential upgradient source of PFHxS in groundwater at the Lincoln AASF #1. The following 

section discuss individual areas and specific PFOA and PFOS findings summarized in the ANG 

SI report (Leidos 2019).
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3.2.1.1 Aircraft Parking Ramp

The Aircraft Parking Ramp was identified due to the fueling and de-fueling, de-icing,

maintenance, and parking of aircraft on the ramp. PFAS contamination levels in surface soil and

groundwater did not exceed the USEPA RSL (USEPA 2018) or HA of 70 ng/L; however, the SI 

recommended further investigation at this site to determine if a previously undetected source 

area exists that is contributing to the PFAS groundwater concentrations, and to determine the 

nature and extent of PFAS in groundwater through sampling of additional new monitoring wells 

located upgradient of and downgradient from the Aircraft Parking Ramp.

3.2.1.2 Fuel Systems Maintenance Hangar

The fuel systems maintenance hangar has a 2,000-gallon AFFF tank fire suppression system. 

There are documented releases from annual testing and spills. When the system was discharged, 

the contents entered the floor drains and discharged into the retention pond. PFAS contamination 

levels in groundwater exceeded the USEPA HA of 70 ng/L. Groundwater results for PFOS and 

PFOA (combined) was reported as 4,380 ng/L. The SI recommended further investigation at the 

Fuel Systems Maintenance Hangar.

3.2.1.3 Current Fire Station

The Current Fire Station since 1999 stores AFFF and had vehicles filled with AFFF that were 

washed at the location. The floor drains discharge to an oil/water separator and then to a sanitary 

sewer system. Nozzle testing occurred on the ramp located west of the station and stormwater 

flowed to Outfall 005. PFAS contamination levels in groundwater exceeded the USEPA HA 

(70 ng/L). Groundwater results for PFOS and PFOA (combined) was reported as 14,300 ng/L. 

The SI recommended further investigation at the Current Fire Station.

3.2.1.4 Main Aircraft Maintenance Hangar

The Main Aircraft Maintenance Hangar had a 2,000-gallon AFFF tank fire suppression system 

from 1997 to 2009. There are documented releases of AFFF from annual testing of the system 

and spills. When the system was discharged prior to 1999, the contents entered the floor drains 

and discharged into the storm sewer. After 1999, system discharges entered floor drains and 

flowed into the retention pond. In 2009, the hangar was retrofitted to have a high expansion foam 

fire suppression system. No AFFF is currently stored or used at the hangar. PFAS contamination 

levels in groundwater exceeded the USEPA HA (70 ng/L). Groundwater results for PFOS and 

PFOA were reported as 14,700 ng/L and 2,630 ng/L, respectively. The SI recommended further 

investigation at The Main Aircraft Maintenance Hangar.

3.2.1.5 Outfall 001

Surface water runoff from the Aircraft Parking Ramp area and the area southwest of the Fuel

Systems Maintenance Hangar collects in Outfall 001. PFAS contamination levels in surface soil

and groundwater were not determined due to a lack of water flow.
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3.2.1.6 Outfall 002

Surface water runoff from the Main Aircraft Maintenance Hangar on the west and south sides of 

the ramp area collects in Outfall 002. PFAS contamination was detected in sediment, but it did 

not exceed the USEPA RSL (USEPA 2018). PFAS contamination levels in surface water 

exceeded the USEPA HA. The surface water result for PFOS and PFOA (combined) was 

reported as 130 ng/L. Recommended to proceed to further investigations. The SI recommended 

further investigation at Outfall 002.

3.2.1.7 Former Fire Station

The Former Fire Station (used from 1978 to 1995) stored AFFF in vehicles and AFFF was used 

to wash vehicles. PFAS contamination levels in groundwater exceeded the USEPA HA (70 

ng/L). Groundwater results for PFOS and PFOA (combined) were reported as 1,630 ng/L. The SI

recommended further investigation at the Former Fire Station.

3.2.1.8 Retention Pond

There is a known release of AFFF that occurred in the Retention Pond based on disposal of 

AFFF and releases from all the hangars. PFAS contamination levels in surface soil and 

groundwater did not exceed the USEPA RSL (USEPA 2018) or USEPA HA (70 ng/L). 

However, the SI recommended further investigation at this site to determine if a previously 

undetected source area exists that is contributing to the PFAS groundwater concentrations, and to 

determine the nature and extent of PFAS in groundwater through sampling of additional new 

monitoring wells located upgradient of and downgradient from the Retention Pond.

3.2.1.9 Outfall 003

All surface water runoff from the former fire station collects in Outfall 003. However, no surface

soil/sediment and groundwater samples were collected and PFAS contamination levels were not

determined due to a lack of water flow.

3.2.1.10 Outfall 004

All surface water runoff from the main aircraft maintenance hangar and the north and south

portion of the ramp area for the Main Hangar collect in Outfall 004. PFAS contamination levels

in surface water exceeded the USEPA HA (70 ng/L). Surface water results for PFOS and PFOA 

(combined) was reported as 34,800 ng/L. PFAS contamination was detected in sediment but did 

not exceed the project action levels. The SI recommended further investigation at Outfall 004.

3.2.1.11 Civil Engineering Building

There was a vehicle maintenance facility on the east end of the Civil Engineering Building from 

1979 to 1999. The building had a pit that discharged PFAS-containing materials to a sanitary 

sewer on the north side of the building. PFAS contamination levels in groundwater exceeded the 

USEPA HA (70 ng/L). Groundwater results for PFOS and PFOA (combined) was reported as 

1,290 ng/L. The SI recommended further investigation at Civil Engineering Building.
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3.2.1.12 Vehicle Maintenance Building

This building has been the Vehicle Maintenance Building since 1999 and has been specifically

used for vehicles that store AFFF. Floor drains discharge to a pit that is pumped to a sanitary

sewer. Any spills or leaks were wiped up with rags and disposed of in the rag waste bin. PFAS

contamination levels in groundwater exceeded the USEPA HA (70 ng/L). Groundwater results 

for PFOS and PFOA (combined) was reported as 780 ng/L. The SI recommended further

investigation at the Vehicle Maintenance Building.

3.2.1.13 Outfall 005

All surface water runoff from the fuel systems maintenance hangar and a small portion of the

ramp area on the south side of the fuel systems maintenance hangar collects in Outfall 005.

Runoff from areas surrounding the Former Fire Station, Civil Engineering Building, and Vehicle 

Maintenance Building also collects in Outfall 005. PFAS contamination levels in surface water 

exceeded the project action levels. Surface water results for PFOS and PFOA (combined) was 

reported as 1,080 ng/L. PFAS contamination was detected in sediment but did not exceed the 

project action levels. The SI recommended further investigation at Outfall 005.

3.2.2 Former Aircraft Fire Training Area

Personnel from the Lincoln ANG recalled seeing pictures of an old aircraft that was used for fire

training activities and located south of the NEARNG boundary. Historically, the Lincoln ANG 

would light a plane on fire, and fire training exercises were conducted to extinguish the fire. 

These exercises reportedly occurred in the 1960s and 1970s. It is not confirmed that AFFF was

used at the Former Aircraft FTA; however, AFFF is considered likely since the Lincoln ANG 

started using AFFF in the 1970s. The Former Aircraft FTA is located on property owned by the

City of Lincoln and is downgradient of the Facility.

3.2.3 Runway Emergency Response

The Lincoln ANG responded to an emergency on the main runway located north of the Lincoln 

ANG facility. Details to the extent of the emergency are unknown; however, Lincoln ANG

personnel reported 1,500 gallons of 3% AFFF were released onto the runway. The runway was 

then flushed with water, which then flowed to the west along a swale. The swale subsequently 

drains to the Old Oak Creek Channel and then to Oak Creek, which ultimately discharges to Salt 

Creek. This potential source area is located upgradient of AOI 1.
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Figure 3-1

Areas of Interest

Former Aircraft FTA

Aircraft

Parking Ramp

Runway

Emergency

Response

Main Aircraft Maintenance

Hangar - Building 600

Retention

Pond

Cold Storage

Vehicle Maintenance - Building 636

Civil Engineering

Building 635

Fuel System Maintenance

Hangar - Building 2600

Current Fire Station

Building 2500

West Lawn

Former FTA

Outfall 001

ABC

Extinguisher FTA

Outfall 004

Outfall 005

Former Fire Station

Former Building 606

Outfall 002

Outfall 003

AOI 1

Oak Creek

3

0 800

Feet

Facility Data

Facility Boundary

ANG Airbase Boundary

Area of Interest

Potential PFAS Release

No Suspected Release

Hydrology

Surface Water Flow Direction

Groundwater Flow Direction

Perennial Creek/Stream

Intermittent Creek/Stream

Waterbody

^_

NE

Data Sources:

ESRI 2020

AECOM 2020

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 AOI

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 the AOI.

4.1 PROBLEM STATEMENT

ARNG will recommend an AOI for remedial investigation (RI) if related soil and groundwater 

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

are presented in Section 6.1 of this report. 

4.2 INFORMATION INPUTS

Primary information inputs for the SI include the following:

• The PA Report for the Lincoln AASF #1 (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). 
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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, Lincoln Army Aviation Support Facility #1, 

Lincoln, 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, Lincoln Army Aviation Support Facility #1, Lincoln, Nebraska, dated October

2021 (EA 2021a)

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

2020b)

• Accident Prevention Plan/Site Safety and Health Plan Addendum, Site Inspections for 

Per- and Polyfluoroalkyl Substances Impacted Sites, ARNG Installations, Nationwide, 

Lincoln AASF #1, Nebraska, Revision 1, dated May 2021 (EA 2021b). 

The SI field activities were conducted from 6 to 8 December, and on 16 December 2021, and 

consisted of direct-push technology (DPT) borings, soil sample collection, temporary monitoring 

well installation, grab groundwater sample collection, and existing monitoring well sampling. 

Field activities were conducted in accordance with the UFP-QAPP Addendum (EA 2021a), 

except as noted in Section 5.10. 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:

• Eighteen (18) soil samples from six locations (DPT boring locations)

• Five (5) surface soil samples from five locations (hand auger locations) 

• Seven (7) grab groundwater samples from temporary well locations

• One (1) groundwater sample from an existing facility monitoring well

• Nine (9) 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 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 

with stakeholders. The combined TPP Meeting 1 and 2 was conducted in general accordance 

with EM 200-1-2. The stakeholders for this SI include ARNG G-9, NEARNG, USACE, and the 

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 

outcome of the combined TPP Meeting 1 and 2 was memorialized in the UFP-QAPP Addendum 

(EA 2022).

A TPP Meeting 3 was held on 15 August 2023 to discuss the results of the SI. Meeting minutes 

for TPP 3 are included in Appendix C of this report. Future TPP meetings will provide an 

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

5.1.2 Utility Clearance

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

clearance was performed at each of the proposed boring locations on 2 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 same 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 
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environment was provided in the Standard Operating Procedures appendix to the Programmatic 

UFP-QAPP (EA 2020a).

5.2 HAND AUGER SOIL SAMPLING

Soil samples were collected from 11 locations for chemical analysis from 0 to 2 ft bgs using a 

hand auger (i.e., five samples were from hand auger only locations and six samples were from 

soil boring locations). All soil sample locations are shown on Figure 5-1. The hand auger 

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). Non-dedicated sampling equipment (i.e., hand auger) was decontaminated between 

sampling locations. 

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) in accordance 

with the UFP-QAPP Addendum. QC samples and analysis were performed as described in the 

UFP-QAPP Addendum (EA 2021a). 

5.3 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 5410 truck-mounted

GeoProbe® dual-tube 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 (with the 

exception of boring locations LAASF-MW-01 and AOI01-MW-01 as noted in Section 5.10):

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

sample was collected approximately 1 ft above the groundwater table, and one collected at the 

mid-point between the surface and the groundwater table (not to exceed 15 ft bgs). Groundwater 

was encountered at depths ranging from 13 to 15 ft bgs during drilling. Total boring completion 

depths, to accommodate temporary well installation, ranged from 20 to 21 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 UFPQAPP 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, 
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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 HDPE bottle and labeled using 

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

standard COC procedures to the laboratory and analyzed for PFAS (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 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. 

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.

5.4 TEMPORARY WELL INSTALLATION AND GROUNDWATER GRAB 

SAMPLING

Temporary wells were installed using a 5410 truck-mounted GeoProbe® 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). 
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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. Three field blanks were 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. 

5.5 EXISTING MONITORING WELL GROUNDWATER SAMPLING

Three existing monitoring wells were proposed for sampling in the UFP-QAPP Addendum (EA 

2021a); however, only one existing monitoring well was sampled as part of the SI as described in 

Section 5.10 and documented using a Field Change Request Form (Appendix B4). Nondedicated sampling materials were decontaminated between well locations. 

Groundwater samples were collected 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 well was purged at a rate determined in the field to reduce 

turbidity and draw down prior to sampling. Water quality parameters (e.g., temperature, specific 

conductance, pH, dissolved oxygen, and oxidation-reduction potential) were measured using a 

water quality meter and recorded on the field sampling form (Appendix B2) after 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). A temperature blank was placed in each cooler to ensure that samples were preserved at 

or below 6°C during shipment.

5.6 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 8 December 

2021 from the newly installed temporary monitoring wells and one existing monitoring well, 

taken from the survey mark on the northern side of the well casing. Groundwater elevation data 

are provided in Table 5-3. 

5.7 SURVEYING

The northern side of each new temporary well casing was surveyed by a Nebraska-licensed 

professional land surveyor. 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 8 December 2021 

and are provided in Appendix B3. 

5.8 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). 
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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 one properly labeled 55-gallon drum, which was labeled and secured in a gravel 

parking area along the southern boundary of the Facility. 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.

5.9 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.

5.10 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. The deviations from the UFP-QAPP 

Addendum are noted below: 

• Hand auger soil boring location AOI01-HA-02 was moved north (downgradient of 

surface drainage flow) in order to avoid infrastructure associated with the geothermal 

well field located in the area. This change was noted in a Field Change Request (provided 

in Appendix B4).

• Soil boring/temporary well locations AOI01-01 and AOI01-02 were moved north of the 

sidewalk due to the underlying footprint of the geothermal well field. Additionally, soil 

boring/temporary well location LAASF-02 was relocated east due to access restrictions 

presented by the surrounding topography. This change was noted in a Field Change 

Request (provided in Appendix B4). 

• Sampling was planned for three existing facility monitoring wells (LAASF-MW-01, 

AOI01-MW-01, and LAASF-MW-02}; however, they were unable to be located during 

initial site reconnaissance. Therefore, groundwater samples representative of these 

locations were planned to be collected from temporary monitoring wells installed using 

DPT (Field Change Request provided in Appendix B4). However, monitoring well 

LAASF-MW-01 was found at the time of sampling and a groundwater sample was 

collected per the UFP-QAPP Addendum (EA 2021a). Additionally, refusal was 
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encountered when relocating boring location LAASF-MW-02. Due to the presence of 

multiple high-profile utilities; therefore, LAASF-MW-02 was removed from the scope of 

this SI (see Field Change Request in Appendix B4). The replacement temporary well for 

location AOI01-MW-01 was drilled as planned. 

• Boring location LAASF-02 was only hand augered to 1 ft bgs due to encountering rocky 

subsurface materials.

• Additional deviations occurred that were not documented on a Field Change Request 

Form. Photographs of field activities were not collected during the SI; therefore, no 

photographic log is presented in this SI report. 

Table 5-1. Samples by Medium

Lincoln AASF #1, Lincoln, 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 9045D0Grain Size (ASTM D422)

Comments

Soil Samples

AOI01-HA-01 12/8/2021 0-2 X

AOI01-HA-02 12/7/2021 0-2 X

AOI01-HA-03 12/7/2021 0-2 X

AOI01-HA-13 12/7/2021 0-2 X Field Duplicate

LAASF-HA-01 12/8/2021 0-2 X

LAASF-HA-02 12/8/2021 0-2 X

AOI01-01-SB-0-2 12/6/2021 0-2 X

AOI01-01-SB-6-7 12/6/2021 6-7 X

AOI01-01-SB-12-13 12/6/2021 12-13 X

AOI01-02-SB-0-2 12/7/2021 0-2 X

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

AOI01-02-SB-12-13 12/7/2021 12-13 X

AOI01-02-SB-14-16 12/7/2021 14-16 X X X pH/TOC and grainsize

AOI01-03-SB-0-2 12/6/2021 0-2 X

AOI01-13-SB-0-2 12/6/2021 0-2 X Field Duplicate

AOI01-03-SB-6-7 12/6/2021 6-7 X

AOI01-03-SB-13-14 12/6/2021 13-14 X

AOI01-04-SB-0-2 12/6/2021 0-2 X

AOI01-04-SB-8-9 12/6/2021 8-9 X

AOI01-04-SB-12-13 12/6/2021 12-13 X

LAASF01-SB-0-2 12/7/2021 0-2 X

LAASF01-SB-8-9 12/7/2021 8-9 X

LAASF01-SB-13-14 12/7/2021 13-14 X

LAASF-02-SB-0-2 12/7/2021 0-2 X

LAASF-02-SB-8-9 12/7/2021 8-9 X

LAASF-02-SB-13-14 12/7/2021 13-14 X

Groundwater Samples

AOI01-01-GW 12/7/2021 - X
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Table 5-2. Soil Boring Depths and Temporary Well Screen Intervals

Lincoln AASF #1, Lincoln, Nebraska

Site Inspection Report

Area of Interest Boring ID

Soil Boring Depth

(ft bgs)

Temporary Well 

Screen Interval

(ft bgs)

1 

AOI01-01 20 15-20

AOI01-02 20 14-19

AOI01-03 21 14-19

AOI01-04 20 15-20

AOI01-MW-01 20 14-19

Facility Boundary

LAASF-01 20 15-20

LAASF-02 20 15-20

LAASF-MW-01* 9.65 —

Notes:

*LAASF-MW-01 is an existing facility monitoring well that was sampled as part of the SI. The 

screen interval is unknown but is assumed to be 5–10 ft bgs. 

Table 5-1. Samples by Medium

Lincoln AASF #1, Lincoln, 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 9045D0Grain Size (ASTM D422)

Comments

AOI01-02-GW 12/7/2021 - X

AOI01-03-GW 12/7/2021 - X

AOI01-04-GW 12/7/2021 - X

AOI01-13-GW 12/7/2021 - X Field Duplicate 

AOI01-MW-01-GW 12/8/2021 - X

LAASF-MW-01-GW 12/8/2021 - X

LAASF-01-GW 12/8/2021 - X

LAASF-02-GW 12/8/2021 - X

Blank Samples/Source Water

LAASF-FB-12062021 12/6/2021 - X Field Blank

LAASF-EB-12062021 12/6/2021 - X Equipment Blank

LAASF-FB-12072021 12/7/2021 - X Field Blank

LAASF-EB-12072021 12/7/2021 - X Equipment Blank

LAASF-FB-12082021 12/8/2021 - X Field Blank

LAASF-EB-12082021 12/8/2021 - X Equipment Blank

DECON_TEST_111021 11/10/2021 - X Source Water
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Table 5-3. Groundwater Elevations

Lincoln AASF #1, Lincoln, 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 1153.47 7.66 6.58 1145.81

AOI01-02 1153.71 7.82 6.93 1145.89

AOI01-03 1153.76 9.22 8.05 1144.54

AOI01-04 1153.51 8.88 7.98 1144.63

AOI01-MW-01 1153.48 7.76 6.07 1145.72

LAASF-01 1152.33 5.31 4.59 1147.02

LAASF-02 1154.14 12.81 12.25 1141.33

LAASF-MW-01 1152.72 6.27 6.35 1146.45

Notes: 

amsl = Above mean sea level

bgs = Below ground surface

btoc = Below top of casing

ft = feet

ID = Identification
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Army National Guard Site Inspections

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Figure 5-1

Site Inspection Sample Locations

<!

AOI01-04

AOI01-02

LAASF-02

LAASF-01

AOI01-03

AOI01-01

AOI01-MW-01

LAASF-HA-01 LAASF-MW-01

AOI01-HA-01

AOI01-HA-02

AOI01-HA-03

LAASF-HA-02

AOI 1

Former Aircraft FTA

Retention Pond

Cold Storage

Vehicle Maintenance

- Building 636

Civil Engineering -

Building 635

West Lawn Former FTA

Outfall 002

Outfall 003

Outfall 001

ABC Extinguisher FTA

Outfall 004

Outfall 005

3

Facility Data

Facility Boundary

ANG Airbase Boundary

Area of Interest

Potential PFAS Release

No Suspected Release

Sample Locations

DPT

<! Monitoring Well

Hand Auger

Hydrology

Surface Water Flow Direction

Inferred Groundwater Flow Direction

Perennial Creek/Stream

Intermittent Creek/Stream

Waterbody

^_

NE

Data Sources:

ESRI 2020

AECOM 2020

0 250

Feet

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. The SLs used in this evaluation are 

presented in Section 6.1. A discussion of the results for the AOI and boundary areas 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, grain size, 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 West Lawn Former FTA. 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 four boring locations/temporary monitoring well 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 9 ft bgs), and deep subsurface 

soil (up to 14 ft bgs). Additionally, surface soil samples (0–2 ft bgs) were collected from three

hand auger boring locations associated with AOI 1. 

PFOS was detected above the SL (13 micrograms per kilogram [μg/kg]) in two of the seven 

surface soils samples at AOI01-02 (14 μg/kg) and AOI01-HA-02 (15 μg/kg). Three other

relevant compounds (PFHxS, PFNA, and PFOA) were detected at concentrations below the 

applicable SLs. The maximum detected concentrations of PFHxS, PFNA, and PFOA were 1.5 

μg/kg, 0.6 J μg/kg, and 1.2 μg/kg, respectively. PFBS was not detected in surface soil samples. 

A total of eight subsurface soil samples were collected from AOI 1 (four shallow subsurface and 

four deep subsurface samples). Three relevant compounds (PFHxS, PFOS, and PFOA) were 

detected in shallow subsurface soil at concentrations below the applicable SLs. The maximum 

detected concentrations of PFHxS, PFOS, and PFOA were 1.1 μg/kg, 2.7 μg/kg, and 0.47 J 
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μg/kg, respectively. PFBS and PFNA were not detected in shallow subsurface soil samples. No 

relevant compounds were detected in the deep subsurface soil samples.

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 five temporary wells associated with AOI 1 during 

the SI. PFHxS, PFOS, and PFOA were detected at concentrations above the applicable SLs in 

four of the five temporary wells. PFHxS detections ranged from 7.6 ng/L (AOI01-03) to 1,800 Jng/L (AOI01-MW-01). PFOS detections ranged from 0.56 J ng/L (AOI01-03) to 2,800 J- ng/L 

(AOI01-MW-01). PFOA detections ranged from 4.1 ng/L (AOI01-03) to 150 ng/L (AOI01-MW01). Additionally, PFBS detections were below the SL of 600 ng/L, with concentrations ranging 

from 4.8 ng/L (AOI01-03) to 310 J- ng/L (AOI01-MW-01). PFNA detections were below the SL 

of 6 ng/L, with concentrations ranging from non-detect (AOI01-03) to 5.9 ng/L (AOI01-MW01). 

6.3.3 AOI 1 – Conclusions

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

PFHxS, PFOS, and PFOA were detected in groundwater samples above their respective SLs. 

Therefore, further evaluation of AOI 1 is warranted.

6.4 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.

6.4.1 Boundary Locations – 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 boundary sample locations were comprised of two boring locations (LAASF-01 and 

LAASF-02) along the Facility boundary. Boring location LAASF-01 was along the 

northern/upgradient boundary of the Facility (adjacent to the downgradient NEANG facility 

boundary). Boring location LAASF-02 was along the southern/downgradient boundary of the 

NEARNG Facility. Soil was sampled from three intervals in the two borings; surface (0–2ft bgs), 

shallow subsurface soil (less than 9 ft bgs), and deep subsurface soil (up to 14 ft bgs).

Additionally, surface soil samples (0–2 ft bgs) were collected from two hand auger boring 

locations. The two hand auger boring locations were associated with surface drainage features 

along the upgradient and downgradient facility boundaries.

PFOS was detected above the SL (13 μg/kg) in two of the four boundary surface soil samples. 

PFOS was detected at a concentration of 84 μg/kg, the maximum PFOS soil concentration 
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detected on-site, at hand auger boring location LAASF-HA-01. This sample was collected at the 

northernmost (downgradient of the AOI) point of the swale that drains surface flow from the 

West Lawn into Old Oak Channel Creek, which separates the Lincoln AASF #1 property from 

the adjacent ANG property. PFOS was detected at a concentration of 43 μg/kg at hand auger 

boring location LAASF-HA-02. This sample was collected from a surface drainage feature 

located toward the southern, downgradient facility boundary that drains the portion of the facility 

south of the West Lawn. Three other relevant compounds (PFHxS, PFNA, and PFOA) were 

detected at concentrations below the applicable SLs. The maximum detected concentrations of 

PFHxS, PFNA, and PFOA were 5.6 μg/kg, 0.4 J μg/kg, and 1.1 μg/kg, respectively. PFBS was 

not detected in surface soil samples.

A total of four subsurface soil samples were collected from the Facility boundary (two shallow 

subsurface and two deep subsurface samples). No relevant compounds were detected in the 

shallow or deep subsurface soil samples.

6.4.2 Boundary Locations – 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 and one existing monitoring well 

associated with the Facility boundaries during the SI. PFHxS, PFNA, PFOS, and PFOA were

detected in groundwater collected from one temporary well assessing the upgradient Facility 

boundary (LAASF-01-GW) at concentrations exceeding the SLs of 39 ng/L, 6 ng/L, 4 ng/L, and 

6 ng/L, respectively. The maximum concentrations of PFHxS, PFNA, PFOS, and PFOA in the 

upgradient well (LAASF-01) were 2,200 ng/L, 9.3 ng/L, 4,700 ng/L, and 250 ng/L, respectively. 

PFBS detections ranged from 1.4 J ng/L (LAASF-02) to 440 ng/L (LAASF-01); however, no 

concentrations of PFBS exceeded the SL of 600 ng/L. There were no exceedances of SLs in 

LAASF-02-GW (downgradient boundary) and LAASF-MW-01-GW (upgradient and to the east 

of LAASF-01).

6.4.3 Conclusions

Based on the results of the SI, PFOS was detected in surface soil above the SL (13 μg/kg) from 

hand auger borings located within surface drainage features at the northern (downgradient of the 

AOI) and southern (downgradient of the AOI) Facility boundaries. The presence of PFAS in the 

hand auger soil samples may indicate a potential release occurred on-site. PFHxS, PFNA, PFOS, 

and PFOA were detected in groundwater at an upgradient temporary well location (LAASF-01)

at concentrations exceeding the associated SLs. Therefore, further evaluation of the Facility 

boundary to determine contribution from potential upgradient sources is warranted.
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Analyte Screening Level1,2 Unit Result Qual Result Qual Result Qual Resul

Perfluorobutanesulfonic acid (PFBS) 1,900 μg/kg ND U ND U ND U ND 

Perfluorohexanesulfonic acid (PFHxS) 130 μg/kg 0.45 J 1.1 0.24 J 0.44 Perfluorononanoic acid (PFNA) 19 μg/kg 0.6 J 0.37 J ND U ND 

Perfluorooctanesulfonic acid (PFOS) 13 μg/kg 7.7 14 1.1 J+ 1.1 

Perfluorooctanoic acid (PFOA) 19 μg/kg 1 0.57 J ND U 0.68 Notes:Values exceeding the Screening Level are shaded gray.J = Estimated concentration.J+ = Estimated concentration, biased high.μg/kg = Microgram(s) per kilogram.ft bgs = Feet below ground surface.Qual = Qualifier.

AOI01-01 AOI01-02 AOI01-03 AO

AOI01

12/6/2021

Parent Sample ID

Sample Date

Depth (ft bgs) 0-2 0-2

12/7/2021

AOI01-01-SB-0-2 AOI01-02-SB-0-2 AOI01-03-SB-0-2 AOI01

12/6/2021 12

0-2 

U = The analyte was not detected at a level greater than or equal to the adjusted detection level.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 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).PFAS by LC/MS/MS compliant with QSM Version 5.3 Table B-15 (g/kg)

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

Site Inspection Report, Lincoln AASF #1

Location ID

Sample Name

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

Lincoln Army Aviation Support Facility #1, Nebraska 

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

Perfluorobutanesulfonic acid (PFBS) 1,900 μg/kg ND U ND U ND U Perfluorohexanesulfonic acid (PFHxS) 130 μg/kg 1.5 1.1 0.55 J Perfluorononanoic acid (PFNA) 19 μg/kg ND U ND U ND U Perfluorooctanesulfonic acid (PFOS) 13 μg/kg 2.4 1.7 2.1 Perfluorooctanoic acid (PFOA) 19 μg/kg 0.53 J 0.39 J 0.26 J 

Notes:Values exceeding the Screening Level are shaded gray.J = Estimated concentration.J+ = Estimated concentration, biased high.μg/kg = Microgram(s) per kilogram.ft bgs = Feet below ground surface.Qual = Qualifier.

AOI01-HA-03 AOI01-HA-13 LAASF-01-SB-0-2 

AOI01-HA AOI01-HA LAASF-01 

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

AOI01-HA-03

Location ID

Sample Name

Parent Sample ID

Sample Date

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

Site Inspection Report, Lincoln AASF #1

12/7/2021 12/7/2021 12/7/2021 

PFAS by LC/MS/MS compliant with QSM Version 5.3 Table B-15 (g/kg)U = The analyte was not detected at a level greater than or equal to the adjusted detection level.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 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).

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

Lincoln Army Aviation Support Facility #1, Nebraska 

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

Perfluorobutanesulfonic acid (PFBS) 25,000 μg/kg ND U ND U ND 

Perfluorohexanesulfonic acid (PFHxS) 1,600 μg/kg 0.92 1.1 ND Perfluorononanoic acid (PFNA) 250 μg/kg ND U ND U ND 

Perfluorooctanesulfonic acid (PFOS) 160 μg/kg ND U 2.7 ND 

Perfluorooctanoic acid (PFOA) 250 μg/kg 0.47 J 0.29 J 0.26 Notes:J = Estimated concentration.μg/kg = Microgram(s) per kilogram.ft bgs = Feet below ground surface.Qual = Qualifier.

AOI01-01-SB-6-7 AOI01-02-SB-6-7 AOI01-03-S

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

Site Inspection Report, Lincoln AASF #1

AOI01-01 AOI01-02 AOI01-0

6-7 6-7

12/6/2021 12/7/2021

6-7 

12/6/202

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. ND = Analyte not detected above the LOD (LOD values are presented in Appendix F).

Location ID

Sample Name

Parent Sample ID

Sample Date

Depth (ft bgs)

U = The analyte was not detected at a level greater than or equal to the adjusted detection level.PFAS by LC/MS/MS compliant with QSM Version 5.3 Table B-15 (g/kg)

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

Lincoln Army Aviation Support Facility #1, Nebraska Version: FINAL

EA Engineering, Science, and Technology, Inc., PBC 6-8

This page intentionally left blank
Site Inspection Report

Lincoln Army Aviation Support Facility #1, Nebraska 

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

PFAS by LC/MS/MS compliant with QSM Version 5.3 Table B-15 (g/kg)Perfluorobutanesulfonic acid (PFBS) 25,000 g/kg ND U ND U ND U 

Perfluorohexanesulfonic acid (PFHxS) 1,600 g/kg ND U ND U ND U Perfluorononanoic acid (PFNA) 250 g/kg ND U ND U ND U Perfluorooctanesulfonic acid (PFOS) 160 g/kg ND U ND U ND U Perfluorooctanoic acid (PFOA) 250 g/kg ND U ND U ND U Notes:U = The analyte was not detected at a level greater than or equal to the adjusted detection level.μg/kg = Microgram(s) per kilogram.ft bgs = Feet below ground surface.Qual = Qualifier.

12-13 12-13 13-14

12/6/2021 12/7/2021 12/6/2021

AOI01-01-SB-12-13 AOI01-02-SB-12-13 

AOI01-03-SB-13

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

 Site Inspection Report, Lincoln AASF #1

Location ID AOI01-01 AOI01-02 AOI01-03 

ND = Analyte not detected above the LOD (LOD values are presented in Appendix F).

Sample Name

Parent Sample ID

Sample Date

Depth (ft bgs)

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. 

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

Lincoln Army Aviation Support Facility #1, Nebraska Version: FINAL

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

This page intentionally left blank
Site Inspection Report

Lincoln Army Aviation Support Facility #1, Nebraska 

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

PFAS by LC/MS/MS compliant with QSM Version 5.3 Table B-15 (ng/L)Perfluorobutanesulfonic acid (PFBS) 601 ng/L 87 43 4.3 4.8 230 Perfluorohexanesulfonic acid (PFHxS) 39 ng/L 740 J- 230 7.6 7.9 1300 Perfluorononanoic acid (PFNA) 6 ng/L 1.8 0.7 J ND U ND U 4.2 Perfluorooctanesulfonic acid (PFOS) 4 ng/L 580 J- 100 0.56 J 0.57 J 1900 Perfluorooctanoic acid (PFOA) 6 ng/L 62 16 4.1 4.2 140 Notes:Values exceeding the Screening Level are shaded gray.J = Estimated concentration.J- = Estimated concentration, biased low.ng/L = Nanogram(s) per liter.Qual = Qualifier.

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

 Site Inspection Report, Lincoln AASF #1

AOI01-03 AOI0

AOI01-01-GW AOI01-02-GW AOI01-03-GW 

AOI01-01 AOI01-02 AOI01-03

AOI01-13-GW AOI01-

12/7/2021 12/7/2021 12/7/2021 12/7/2021 12/7/

AOI01-03-GW

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.ND = Analyte not detected above the LOD (LOD values are presented in Appendix F).

Location ID

Sample Name

Parent Sample ID

Sample Date

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

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

Lincoln Army Aviation Support Facility #1, Nebraska Version: FINAL

EA Engineering, Science, and Technology, Inc., PBC 6-12

This page intentionally left blank
Army National Guard Site Inspections

Site Inspection Report

Lincoln AASF #1, Nebraska

Figure 6-1

AOI 1

PFOS Detections in Soil

AOI01-04

AOI01-02

LAASF-02

LAASF-01

AOI01-03

AOI01-01

LAASF-HA-01

AOI01-HA-01

AOI01-HA-02

AOI01-HA-03

LAASF-HA-02

AOI 1

Former Aircraft FTA

Retention Pond

Cold Storage

Vehicle Maintenance

- Building 636

Civil Engineering -

Building 635

West Lawn Former FTA

Outfall 002

Outfall 003

Outfall 001

ABC Extinguisher FTA

Outfall 004

Outfall 005

AOI01-04

AOI01-02

LAASF-02

LAASF-01

AOI01-03

AOI01-01

AOI 1

Former Aircraft FTA

Retention Pond

Cold Storage

Vehicle Maintenance

- Building 636

Civil Engineering -

Building 635

West Lawn Former FTA

Outfall 002

Outfall 003

Outfall 001

ABC Extinguisher FTA

Outfall 004

Outfall 005

AOI01-04

AOI01-02

LAASF-02

LAASF-01

AOI01-03

AOI01-01

AOI 1

Former Aircraft FTA

Retention Pond

Cold Storage

Vehicle Maintenance

- Building 636

Civil Engineering -

Building 635

West Lawn Former FTA

Outfall 002

Outfall 003

Outfall 001

ABC Extinguisher FTA

Outfall 004

Outfall 005

3

0 250

Feet

^_

NE

Data Sources:

ESRI 2022

AECOM 2019

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

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

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

Projection:........WGS 84 UTM 13N

0 250

Feet

0 250

Feet

Shallow Intermediate Deep

Facility Data

Facility Boundary

ANG Airbase Boundary

Potential PFAS Release

No Suspected Release

Hydrology

Surface Water Flow Direction

Groundwater Flow Direction

Perennial Creek/Stream

> 1,600

> 160 - 1,600

> 13 - 160

> ND - 13

ND (Non-Detect)

PFOS Results (μg/Kg)

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)
Site Inspection Report

Lincoln Army Aviation Support Facility #1, Nebraska ` Version: FINAL

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

This page intentionally left blank
Figure 6-2

AOI 1

PFOA Detections in Soil

AOI01-04

AOI01-02

LAASF-02

LAASF-01

AOI01-03

AOI01-01

LAASF-HA-01

AOI01-HA-01

AOI01-HA-02

AOI01-HA-03

LAASF-HA-02

AOI 1

Former Aircraft FTA

Retention Pond

Cold Storage

Vehicle Maintenance

- Building 636

Civil Engineering -

Building 635

West Lawn Former FTA

Outfall 002

Outfall 003

Outfall 001

ABC Extinguisher FTA

Outfall 004

Outfall 005

AOI01-04

AOI01-02

LAASF-02

LAASF-01

AOI01-03

AOI01-01

AOI 1

Former Aircraft FTA

Retention Pond

Cold Storage

Vehicle Maintenance

- Building 636

Civil Engineering -

Building 635

West Lawn Former FTA

Outfall 002

Outfall 003

Outfall 001

ABC Extinguisher FTA

Outfall 004

Outfall 005

AOI01-04

AOI01-02

LAASF-02

LAASF-01

AOI01-03

AOI01-01

AOI 1

Former Aircraft FTA

Retention Pond

Cold Storage

Vehicle Maintenance

- Building 636

Civil Engineering -

Building 635

West Lawn Former FTA

Outfall 002

Outfall 003

Outfall 001

ABC Extinguisher FTA

Outfall 004

Outfall 005

3

0 250

Feet

^_

NE

0 250

Feet

0 250

Feet

Shallow Intermediate Deep

Army National Guard Site Inspections

Site Inspection Report

Lincoln AASF #1, Nebraska

Data Sources:

ESRI 2022

AECOM 2019

Facility Data

Facility Boundary

ANG Airbase Boundary

Potential PFAS Release

No Suspected Release

Hydrology

Surface Water Flow Direction

Groundwater Flow Direction

Perennial Creek/Stream

> 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)

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.

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

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

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

Projection:........WGS 84 UTM 13N
Site Inspection Report

Lincoln Army Aviation Support Facility #1, Nebraska ` Version: FINAL

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

This page intentionally left blank
Figure 6-3

AOI 1

PFBS Detections in Soil

AOI01-04

AOI01-02

LAASF-02

LAASF-01

AOI01-03

AOI01-01

LAASF-HA-01

AOI01-HA-01

AOI01-HA-02

AOI01-HA-03

LAASF-HA-02

AOI 1

Former Aircraft FTA

Retention Pond

Cold Storage

Vehicle Maintenance

- Building 636

Civil Engineering -

Building 635

West Lawn Former FTA

Outfall 002

Outfall 003

Outfall 001

ABC Extinguisher FTA

Outfall 004

Outfall 005

AOI01-04

AOI01-02

LAASF-02

LAASF-01

AOI01-03

AOI01-01

AOI 1

Former Aircraft FTA

Retention Pond

Cold Storage

Vehicle Maintenance

- Building 636

Civil Engineering -

Building 635

West Lawn Former FTA

Outfall 002

Outfall 003

Outfall 001

ABC Extinguisher FTA

Outfall 004

Outfall 005

AOI01-04

AOI01-02

LAASF-02

LAASF-01

AOI01-03

AOI01-01

AOI 1

Former Aircraft FTA

Retention Pond

Cold Storage

Vehicle Maintenance

- Building 636

Civil Engineering -

Building 635

West Lawn Former FTA

Outfall 002

Outfall 003

Outfall 001

ABC Extinguisher FTA

Outfall 004

Outfall 005

3

0 250

Feet

^_

NE

0 250

Feet

0 250

Feet

Shallow Intermediate Deep

Army National Guard Site Inspections

Site Inspection Report

Lincoln AASF #1, Nebraska

Data Sources:

ESRI 2022

AECOM 2019

Facility Data

Facility Boundary

ANG Airbase Boundary

Potential PFAS Release

No Suspected Release

Hydrology

Surface Water Flow Direction

Groundwater Flow Direction

Perennial Creek/Stream

> 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)

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.

> 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 13N
Site Inspection Report

Lincoln Army Aviation Support Facility #1, 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

Lincoln AASF #1, Nebraska

Figure 6-4

AOI 1

PFHxS Detections in Soil

AOI01-04

AOI01-02

LAASF-02

LAASF-01

AOI01-03

AOI01-01

LAASF-HA-01

AOI01-HA-01

AOI01-HA-02

AOI01-HA-03

LAASF-HA-02

AOI 1

Former Aircraft FTA

Retention Pond

Cold Storage

Vehicle Maintenance

- Building 636

Civil Engineering -

Building 635

West Lawn Former FTA

Outfall 002

Outfall 003

Outfall 001

ABC Extinguisher FTA

Outfall 004

Outfall 005

AOI01-04

AOI01-02

LAASF-02

LAASF-01

AOI01-03

AOI01-01

AOI 1

Former Aircraft FTA

Retention Pond

Cold Storage

Vehicle Maintenance

- Building 636

Civil Engineering -

Building 635

West Lawn Former FTA

Outfall 002

Outfall 003

Outfall 001

ABC Extinguisher FTA

Outfall 004

Outfall 005

AOI01-04

AOI01-02

LAASF-02

LAASF-01

AOI01-03

AOI01-01

AOI 1

Former Aircraft FTA

Retention Pond

Cold Storage

Vehicle Maintenance

- Building 636

Civil Engineering -

Building 635

West Lawn Former FTA

Outfall 002

Outfall 003

Outfall 001

ABC Extinguisher FTA

Outfall 004

Outfall 005

3

0 250

Feet

^_

NE

Data Sources:

ESRI 2022

AECOM 2019

0 250

Feet

0 250

Feet

Shallow Intermediate Deep

Facility Data

Facility Boundary

ANG Airbase Boundary

Potential PFAS Release

No Suspected Release

Hydrology

Surface Water Flow Direction

Groundwater Flow Direction

Perennial Creek/Stream

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 13N
Site Inspection Report

Lincoln Army Aviation Support Facility #1, 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

Lincoln AASF #1, Nebraska

Figure 6-5

AOI 1

PFNA Detections in Soil

AOI01-04

AOI01-02

LAASF-02

LAASF-01

AOI01-03

AOI01-01

LAASF-HA-01

AOI01-HA-01

AOI01-HA-02

AOI01-HA-03

LAASF-HA-02

AOI 1

Former Aircraft FTA

Retention Pond

Cold Storage

Vehicle Maintenance

- Building 636

Civil Engineering -

Building 635

West Lawn Former FTA

Outfall 002

Outfall 003

Outfall 001

ABC Extinguisher FTA

Outfall 004

Outfall 005

AOI01-04

AOI01-02

LAASF-02

LAASF-01

AOI01-03

AOI01-01

AOI 1

Former Aircraft FTA

Retention Pond

Cold Storage

Vehicle Maintenance

- Building 636

Civil Engineering -

Building 635

West Lawn Former FTA

Outfall 002

Outfall 003

Outfall 001

ABC Extinguisher FTA

Outfall 004

Outfall 005

AOI01-04

AOI01-02

LAASF-02

LAASF-01

AOI01-03

AOI01-01

AOI 1

Former Aircraft FTA

Retention Pond

Cold Storage

Vehicle Maintenance

- Building 636

Civil Engineering -

Building 635

West Lawn Former FTA

Outfall 002

Outfall 003

Outfall 001

ABC Extinguisher FTA

Outfall 004

Outfall 005

3

0 250

Feet

^_

NE

Data Sources:

ESRI 2022

AECOM 2019

0 250

Feet

0 250

Feet

Shallow Intermediate Deep

Facility Data

Facility Boundary

ANG Airbase Boundary

Potential PFAS Release

No Suspected Release

Hydrology

Surface Water Flow Direction

Groundwater Flow Direction

Perennial Creek/Stream

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 13N
Site Inspection Report

Lincoln Army Aviation Support Facility #1, Nebraska ` Version: FINAL

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

This page intentionally left blank
Figure 6-6

AOI 1

PFOA, PFOS and PFBS Detections in Groundwater

AOI01-04

AOI01-02

LAASF-02

LAASF-01

AOI01-03

AOI01-01

AOI01-MW-01

LAASF-MW-01

AOI 1

Former Aircraft FTA

Retention Pond

Cold Storage

Vehicle Maintenance

- Building 636

Civil Engineering -

Building 635

West Lawn Former FTA

Outfall 002

Outfall 003

Outfall 001

ABC Extinguisher FTA

Outfall 004

Outfall 005

AOI01-04

AOI01-02

LAASF-02

LAASF-01

AOI01-03

AOI01-01

AOI01-MW-01

LAASF-MW-01

AOI 1

Former Aircraft FTA

Retention Pond

Cold Storage

Vehicle Maintenance

- Building 636

Civil Engineering -

Building 635

West Lawn Former FTA

Outfall 002

Outfall 003

Outfall 001

ABC Extinguisher FTA

Outfall 004

Outfall 005

3

0 250

Feet

^_

NE

0 250

Feet

PFOA PFOS

AOI01-04

AOI01-02

LAASF-02

LAASF-01

AOI01-03

AOI01-01

AOI01-MW-01

LAASF-MW-01

AOI 1

Former Aircraft FTA

Retention Pond

Cold Storage

Vehicle Maintenance

- Building 636

Civil Engineering -

Building 635

West Lawn Former FTA

Outfall 002

Outfall 003

Outfall 001

ABC Extinguisher FTA

Outfall 004

Outfall 005

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

Lincoln AASF #1, Nebraska

Data Sources:

ESRI 2022

AECOM 2019

Facility Data

Facility Boundary

ANG Airbase Boundary

Potential PFAS Release

No Suspected Release

Hydrology

Surface Water Flow Direction

Groundwater Flow Direction

Perennial Creek/Stream

> 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

> 601 - 1,000

> 100 - 601

> ND - 100

ND (Non-Detect)

PFBS Results (ng/L)

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

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

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

Projection:........WGS 84 UTM 13N
Site Inspection Report

Lincoln Army Aviation Support Facility #1, 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

Lincoln AASF #1, Nebraska

Figure 6-7

AOI 1

PFHxS and PFNA Detections in Groundwater

Former Aircraft FTA

Retention Pond

Cold Storage

Vehicle Maintenance -

Building 636

Civil Engineering -

 Building 635

West Lawn Former FTA

Outfall 002

Outfall 003

Outfall 001

ABC Extinguisher FTA

Outfall 004

Outfall 005

AOI 1

LAASF-02

AOI01-04

AOI01-03

AOI01-02

AOI01-01

LAASF-01

AOI01-MW-01

LAASF-MW-01

Former Aircraft FTA

Retention Pond

Cold Storage

Vehicle Maintenance -

Building 636

Civil Engineering -

 Building 635

West Lawn Former FTA

Outfall 002

Outfall 003

Outfall 001

ABC Extinguisher FTA

Outfall 004

Outfall 005

AOI 1

LAASF-02

AOI01-04

AOI01-03

AOI01-02

AOI01-01

LAASF-01

AOI01-MW-01

LAASF-MW-01

3

0 300

Feet

Facility Data

Facility Boundary

ANG Airbase Boundary

Potential PFAS Release

No Suspected Release

Hydrology

Surface Water Flow Direction

Groundwater Flow Direction

Perennial Creek/Stream

^_

NE

Data Sources:

ESRI 2020

AECOM 2020

Path: G:\Federal\Nationwide\PFAS\MAES_634250383\PROJECTS\SIReport\Lincoln\LincolnSIReport.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 13N
Site Inspection Report

Lincoln Army Aviation Support Facility #1, Nebraska ` Version: FINAL

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Site Inspection Report

Lincoln Army Aviation Support Facility #1, Nebraska Version: FINAL

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

7. EXPOSURE PATHWAYS

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

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

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

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

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

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

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

potentially complete when the following conditions are present:

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 AOI 1 based on the 

aforementioned criteria.
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7.1.1 AOI 1 

Located west of the main hangar, the West Lawn Former FTA is considered a potential release 

area due to a written statement from a former NEARNG employee indicating that fire training 

exercises were conducted on the West Lawn, dispensing “foam” sometime in the 1990s.

PFOS was detected in surface soil at AOI 1 at concentrations above the SL. Additionally, PFAS 

was detected in surface soil samples collected from the downgradient drainage features (i.e., 

Facility boundary samples) at concentrations above the SL. Although the ground surface at AOI 

appears to be well vegetated making it less likely that exposure to surface soil would occur,

ground-disturbing activities could result in site worker and construction worker exposure to 

PFAS compounds via ingestion or inhalation of dust. Therefore, the exposure pathway for 

inhalation and ingestion are considered to be potentially complete with an exceedance of the SL 

for these receptors.

PFHxS, PFOS, and PFOA were additionally detected in shallow subsurface soil at a 

concentration below the applicable SLs. Ground disturbing activities to subsurface soil could 

result in construction worker exposure to detectable concentrations of these relevant compounds 

via incidental ingestion. Therefore, the exposure pathway for subsurface soil is potentially 

complete for the construction worker. The site worker/trespasser activities are anticipated to be 

limited to surface or near surface soil; therefore, the exposure pathway for this receptor group to 

subsurface soil is considered incomplete.

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 

PFHxS, PFOS, and PFOA were detected in groundwater at concentrations above applicable SLs 

collected from five temporary wells associated with AOI 1. Due to the depth to groundwater at 

AOI 1 (13 to 15 ft bgs), it is possible that construction workers would be exposed to PFAS 

through the groundwater via ingestion during trenching activities. Therefore, the exposure

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

complete with an exceedance of the SL. 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 leaving the facility (facility Boundary) 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. 
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7.3 SURFACE WATER AND SEDIMENT EXPOSURE PATHWAY

7.3.1 AOI 1 

PFOS was detected at concentrations above the SL in surface soils taken from perennial drainage 

pathways discharging to Oak Creek (drainages were dry at the time of sampling). PFAS 

constituents are highly water soluble, and, as a result, it is possible that PFAS migrated to Oak 

Creek. No surface water or sediment sampling was conducted at the Lincoln AASF #1; therefore, 

the exposure pathways for site workers, construction workers, and off-site recreational users of 

Oak Creek (and its on-site tributaries) via ingestion of surface water and sediment are considered 

potentially complete. Off-site residents receive drinking water from the City of Lincoln Water 

System; therefore, Oak Creek (and its tributaries) is not a source of drinking water and the 

resident receptor pathway is considered incomplete. The CSM is presented in Figure 7-1. 
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Notes:

1. No current active construction at the facility.

2. The resident and recreational users refer to 

off-site receptors.

3. Inhalation of dust for off-site receptors is 

likely insignificant. Figure 7-1

Conceptual Site Model

AOI 1

RECEPTOR

Human Receptors:

Current/Future

Site Worker / 

Trespasser

Construction 

Worker1 Resident2,3

Site 

Worker

Construction 

Worker

Resident1

AOI 1 –

West 

Lawn 

Former 

FTA

PFAS in 

Surface 

Soil

Human 

Activities

Precipitation/

Run-Off

Leaching/

Infiltration

Airborne 

Soil 

Particulate

Surface Soil 

at AOI

Surface 

Water/ 

Sediment

Subsurface 

Soil

Shallow 

Groundwater

Ingestion

Ingestion

Ingestion

Ingestion

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

Potential Fire 

Training

SOURCE

Source Release 

Mechanism Media

PATHWAY

Transport

and Migration Media Exposure 

Routes

Inhalation 

of Dust

Potentially Complete Pathway with Exceedance of 

Screening Level

Recreational 

User2,3

Recreational 

User1
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Site Inspection Report

Lincoln Army Aviation Support Facility #1, 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 from 6 to 8 December 2021, and on 

16 December 2021. The SI field activities included soil sample collection (hand augers and 

borings), temporary monitoring well installation, grab groundwater sample collection, existing 

monitoring well sampling, and land surveying. Field activities were conducted in accordance 

with the UFP-QAPP Addendum (EA 2021a), except as previously noted in Section 5.10. 

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 PFAS by LC/MS/MS compliant with QSM 

Version 5.3 Table B-15 as follows:

• Eighteen (18) soil samples from six locations (DPT boring locations)

• Five (5) soil samples from five locations (hand auger locations) 

• Seven (7) grab groundwater samples from temporary well locations

• One (1) groundwater sample from an existing facility monitoring wells

• Nine (9) QA/QC samples

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

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

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

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

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

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

described in Section 7.

8.2 OUTCOME

Based on the results of this SI, further evaluation under CERCLA is warranted for AOI 1 

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

on the SI findings, concentrations of relevant compounds were above applicable SLs in surface 

soil and groundwater at AOI 1 from sources potentially on the facility and at the facility 

boundary from potential upgradient off-facility sources. Sample chemical analytical 

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

groundwater, as described in Table 6-1.
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A summary of the results of the SI data relative to the SLs is as follows:

• AOI 1:

 PFHxS, PFOS, and PFOA were detected above applicable SLs in groundwater 

collected from four temporary well locations associated with the AOI. PFOS was 

detected above the applicable SL in surface soil associated with AOI 1. Based on the 

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

• The Facility boundary: 

 PFHxS, PFOS, and PFOA were detected in groundwater at the upgradient boundary 

at concentrations exceeding the SLs. There were no exceedances in groundwater 

collected from the downgradient boundary location. PFOS was detected above the 

applicable SL in surface soil collected from at the upgradient and downgradient 

boundary boring locations. Based on the results of the SI, further evaluation of the 

Facility boundary to determine contribution from potential upgradient sources is 

warranted. 

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

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

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

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

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

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

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

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

be considered for further investigation under CERCLA and undergo an RI. 

Table 8-1. Summary of Site Inspection Findings and Recommendations

AOI Potential Release Area

Soil

Source Area

Groundwater

Source Area

Groundwater

Facility Boundary Future Action

1 West Lawn Former Fire 

Training Area Proceed to RI

Legend:

 = Detected; exceedance of screening levels.

 = Detected; no exceedance of screening levels.

 = Not detected.
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9. REFERENCES

AECOM Technical Services, Inc. (AECOM). 2020. Final Preliminary Assessment Report, 

Lincoln Army Aviation Support Facility #1, Lincoln, Nebraska. September.

Assistant Secretary of Defense. 2022. Investigation Per- and Polyfluoroalkyl Substances within 

The Department of Defense Cleanup Program. July.

Department of the Army. 2016. EM-200-1-2, Environmental Quality, Technical Project 

Planning Process. 29 February.

Department of Defense (DoD). 2019a. Department of Defense (DoD), Department of Energy

(DOE) Consolidated Quality Systems Manual (QSM) for Environmental Laboratories,

Version 5.3. May.

. 2019b. General Data Validation Guidelines. November.

. 2020. Data Validation Guidelines Module 3: Data Validation Procedure for Per- and 

Polyfluoroalkyl Substances Analysis by QSM Table B-15. May.

EA, Engineering, Science, and Technology, PBC (EA). 2020a. Final Programmatic Uniform 

Federal Policy Quality Assurance Project Plan, Site Inspections for Per- and 

Polyfluoroalkyl Substances Impacted Sites, ARNG Installations, Nationwide. December.

———. 2020b. Final Programmatic Accident Prevention Plan, Revision 1. November.

. 2021a. Final Site Inspection Uniform Federal Policy Quality Assurance Project Plan 

(UFP-QAPP) Addendum, Lincoln Army Aviation Support Facility #1, Lincoln, Nebraska, 

Per- and Polyfluoroalkyl Substances Impacted Sites ARNG Installations, Nationwide. 

October.

———. 2021b. Accident Prevention Plan / Site Safety and Health Plan Addendum, Site 

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

Nationwide, Lincoln AASF #1, Nebraska, Revision 1. May.

EDR. 2019. EDR Radius Map TM Report with GeoCheck ®, Lincoln Army Aviation Support 

Facility #1. November.

Guelfo, J.L. and C.P. Higgins. 2013. Subsurface transport potential of perfluoroalkyl acids and 

aqueous film-forming foam (AFFF)-impacted sites. Environ. Sci. Technol. 47(9):4164-

71. 

Higgins, C.P. and R.G. Luthy. 2006. Sorption of perfluorinated surfactants on sediments. 

Environ. Sci. Technol. 40(23):7251-7256. 
Site Inspection Report

Lincoln Army Aviation Support Facility #1, Nebraska Version: FINAL

EA Engineering, Science, and Technology, Inc., PBC 9-2

Interstate Technology Regulatory Council (ITRC). 2018. Environmental Fate and Transport for 

Per- and Polyfluoroalkyl Substances. March. 

Leidos. 2019. Final Site Inspection Report for Perfluorooctane Sulfonate and Perfluorooctanoic 

Acid at Lincoln Air National Guard Base, Lincoln, Nebraska. December.

U.S. Environmental Protection Agency (USEPA). 1980. Comprehensive Environmental

Response, Compensation, and Liability Act (CERCLA). 11 December.

. 1994. National Oil and Hazardous Substances Pollution Contingency Plan (Final Rule).

40 Code of Federal Regulations Part 300; 59 Federal Register 47384. September.

. 2001. Risk Assessment Guidance for Superfund, Volume I: Human Health Evaluation

Manual (Part D, Standardized Planning, Reporting, and Review of Superfund Risk 

Assessments). December.

. 2016a. Drinking Water Health Advisory for Perfluorooctane Sulfonate. Office of Water, 

Health and Ecological Criteria Division. EPA Document Number EPA 822-R-16-004. May. 

. 2016b. Drinking Water Health Advisory for Perfluorooctonic Acid. Office of Water, Health 

and Ecological Criteria Division. EPA Document Number EPA 822-R-16-005. May. 

. 2017. National Functional Guidelines for Organic Superfund Data Review. OLEM 9355.0-

136, EPA-540-R-2017-002. Office of Superfund Remediation and Technology Innovation. 

January. 

. 2018. Regional Screening Levels (RSL) Tables. Updated May 2018.

U.S. Fish and Wildlife Service. 2022. Endangered Species. http://ecos.fws.gov/ipac/. Accessed 

on 20 January. 

Xiao, F., M.F. Simcik, T.R. Halbach, and J.S Gulliver. 2015. Perfluorooctane sulfonate (PFOS) 

and perfluorooctanoate (PFOA) in soils and groundwater of a U.S. metropolitan area: 

Migration and implications for human exposure. Water Research 72:64-74.