FINAL

Preliminary Assessment Report

Duncan Armory AASF,

New Castle, Delaware

Perfluorooctanesulfonic Acid (PFOS) and Perfluorooctanoic 

Acid (PFOA) Impacted Sites

ARNG Installations, Nationwide

June 2020

Prepared for:

Army National Guard Headquarters 

111 S. George Mason Drive

Arlington, VA 22204

UNCLASSIFIED
PFAS Preliminary Assessment Report

Duncan Armory AASF, New Castle, Delaware

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Table of Contents

Executive Summary ......................................................................................................................1

1. Introduction..........................................................................................................................5

Authority and Purpose................................................................................................5

Preliminary Assessment Methods ..............................................................................5

Report Organization ...................................................................................................6

Facility Location and Description................................................................................6

Facility Environmental Setting ....................................................................................6

1.5.1 Geology ...........................................................................................................7

1.5.2 Hydrogeology ..................................................................................................7

1.5.3 Hydrology ........................................................................................................8

1.5.4 Climate ............................................................................................................9

1.5.5 Current and Future Land Use..........................................................................9

2. Fire Training Areas.............................................................................................................13

3. Non-Fire Training Areas.....................................................................................................14

Hangar......................................................................................................................14

4. Emergency Response Areas .............................................................................................16

Helicopter Crash Site ...............................................................................................16

5. Adjacent Sources...............................................................................................................18

Delaware Auto Salvage Fire.....................................................................................18

Delaware State Fire School......................................................................................18

Aircraft Crash Site ....................................................................................................18

DANG Fire Training Area..........................................................................................18

Airplane Crash Site ..................................................................................................18

6. Preliminary Conceptual Site Model....................................................................................20

AOI 1 Helicopter Crash Site .....................................................................................20

7. Conclusions .......................................................................................................................23

Findings....................................................................................................................23

Uncertainties ............................................................................................................23

Potential Future Actions ...........................................................................................24

8. References ........................................................................................................................27
PFAS Preliminary Assessment Report

Duncan Armory AASF, New Castle, Delaware

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Tables

Table ES-1 AOIs at DAASF 

Table 7-1 AOIs at DAASF 

Table 7-2 No Suspected Release Areas

Table 7-3 Uncertainties

Table 7-4 PA Findings Summary

Figures

Figure ES-1 Summary of Findings AOI 1 

Figure ES-2 Preliminary Conceptual Site Model for DAASF 

Figure 1-1 Facility Location

Figure 1-2 Groundwater Features

Figure 1-3 Surface Water Features

Figure 3-1 Non-Fire Training Areas

Figure 4-1 Emergency Response Areas

Figure 5-1 Adjacent Sources

Figure 6-1 Area of Interest 1 

Figure 6-2 Preliminary Conceptual Site Model for AOI 1 Helicopter Crash Site

Figure 7-1 Summary of Findings AOI 1 

Appendices

Appendix A Data Resources

Appendix B Preliminary Assessment Documentation

 B.1 Interview Records

 B.2 Visual Site Inspection Checklists

 B.3 Conceptual Site Model Information

Appendix C Photographic Log
PFAS Preliminary Assessment Report

Duncan Armory AASF, New Castle, Delaware

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Acronyms and Abbreviations

oF Degrees Fahrenheit

μg/L Micrograms per Liter

AECOM AECOM Technical Services, Inc.

AFFF Aqueous Film Forming Foam

AOI Area of Interest

amsl Above Mean Sea Level

ANG Air National Guard

ARNG Army National Guard

bmsl Below Mean Sea Level

CERCLA Comprehensive Environmental Response, Compensation, and Liability 

Act

CFR Code of Federal Regulations

CSM

DAASF

Conceptual Site Model

Duncan Armory Army Aviation Support Facility

DANG Delaware Air National Guard

DEARNG Delaware Army National Guard

DGS Delaware Geological Survey

DNREC Delaware Department of Natural Resources and Environmental Control

DRBC Delaware River Basin Commission

DoD Department of Defense

EDRTM Environmental Data Resources, Inc.TM

FD Fire Department

FTA Fire Training Area

HA USEPA’s Lifetime Health Advisory

NCCDE New Castle County Delaware

PA Preliminary Assessment

PFAS Per- and Poly-Fluoroalkyl Substances

PFOA Perfluorooctanoic Acid

PFOS Perfluorooctanesulfonic Acid

SI Site Inspection

US United States

USACE United States Army Corps of Engineers

USEPA United States Environmental Protection Agency

USGS United States Geological Survey

VSI Visual Site Inspection
PFAS Preliminary Assessment Report

Duncan AASF, New Castle, Delaware 

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Executive Summary

The Army National Guard (ARNG) is performing Prelimnary Assessments (PAs) and Site 

Inspections (SIs) for Perfulorooctanesulfonic acid (PFOS) and Perfluorooctanoic acid (PFOA) 

Impacted Sites at ARNG Facilities Nationwide. A PA for per- and polyfluoroalkyl substances 

(PFAS)-containing materials was completed for Duncan Armory Army Aviation Support Facility

(DAASF; also referred to as the “facility”) in New Castle, Delaware, to assess potential PFAS 

release areas and exposure pathways to receptors. DAASF is constructed on a parcel of land 

owned by the Transportation Board for New Castle County and leased to DAASF. According to 

the lease document, the lease to DAASF began in 1973 and will be in effect for 50 years. 

The performance of this PA included the following tasks: 

• Reviewed available administrative record documents and Environmental Data Resources, 

Inc. (EDR)TM report packages to obtain information relevant to potential PFAS releases, such 

as: drinking water well locations, historical aerial photographs, Sanborn maps, and 

environmental compliance actions in the area surrounding the facility;

• Conducted a site visit on 6 August 2019 and completed visual site inspections at locations 

where PFAS-containing materials were suspected of being stored, used, or disposed;

• Interviewed current DAASF personnel including environmental managers and operations 

staff during the site visit; 

• Identified areas of interest (AOIs) and developed a preliminary conceptual site model (CSM) 

to summarize potential PFAS source-pathway-receptor linkages for each AOI

One AOI (referred to as “AOI 1”) related to potential PFAS release was identified at DAASF during 

the PA. Aqueous film forming foam (AFFF) may have been used to extinguish a fire at an 

emergency response location. AOI 1 comprises the location at DAASF where a helicopter

crashed, and the resultant fire was extinguished using foam. It is unknown if the foam utilized 

were AFFF, as firsthand interviewee knowledge begins in 1991. The AOI is shown on Figure ES1 and described in Table ES-1 below. The preliminary CSM for DAASF is presented in Figure 

ES-2. 

Table ES-1: AOIs at DAASF

Area of Interest Name Used by Potential Release Date

AOI 1 Helicopter

Crash

Municipal fire department

(FD)

1970s

The area where the aircraft crashed and caught fire is located at the southern border of DAASF, 

near adjacent airport taxiways. Municipal fire response reportedly used firefighting foam to control 

and extinguish the fire at DAASF. It is unknown what types of foam were used by the FD. Potential 

PFAS contamination that may have resulted from fire response at the accident location (AOI 1) 

may have traveled across paved and unpaved ground to a retention basin in the southwest corner 

of the facility. 

A section of New Castle Airport is located upgradient of DAASF, along the southern and eastern 

boundaries, and is a potential off-facility source of PFAS. Additionally, a PFAS investigation is 

ongoing by the Air National Guard (ANG) at the adjacent New Castle ANG Base, located 

approximately 0.8 miles east of the eastern boundary of DAASF. This site has reported both 

groundwater and surface water screening criteria exceedances (AFW, 2019). Based on the US

Environmental Protection Agency (USEPA) Unregulated Contaminant Monitoring Rule 3 data, it 

was indicated that PFAS were detected in a public water system above the USEPA Health 

Advisory (HA) level within 20 miles of the facility (Appendix A). The HA is 70 parts per trillion for 
PFAS Preliminary Assessment Report

Duncan AASF, New Castle, Delaware 

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PFOS and PFOA, individually or combined. PFAS analyses performed in 2016 had method 

detection limits that were higher than currently achievable. Thus, it is possible that low 

concentrations of PFAS were not detected during the UCMR3 but might be detected if analyzed 

today.

Based on a potential PFAS release at the AOI, there is potential for exposure to PFAS 

contamination in airborne soil particulates, surface soil, surface water and sediments to site 

workers, construction workers, and trespassers via ingestion and inhalation; subsurface soil to 

construction workers via ingestion; and groundwater to construction workers and off-facility 

residents.
Christina River

Airplane

Crash

Hangar

DANG Fire

Training

Aircraft

Crash

State of Delaware

Fire Training

Helicopter

Crash Site

AOI 1

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Germantown, MD 20876

Summary of Findings

Base Map: Source: Esri, DigitalGlobe, GeoEye,

Earthstar Geographics, CNES/Airbus DS, USDA, USGS,

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Legend

Area of Interest

Potential PFAS Release

No Suspected Release

Facility Boundary

Water Body

Wetland

River/Stream

0 300 600 1,200

Feet

3
Media

SOURCE PATHWAY RECEPTOR

AOI1

Emergency 

Response to 

Helicopter Crash

PFAS in 

Surface Soil 

and Paved 

Tarmac

Human 

Activities

Precipitation/ 

Run-Off

Leaching/ 

Infiltration

Airborne Soil 

particulate

Surface Soil 

at AOI

Surface 

Water/ 

sediment

Subsurface 

Soil

Shallow 

Groundwater

Source Release 

Mechanism Media Transport and Migration Media Exposure Routes

Inhalation of 

Dust

Ingestion

Ingestion

Ingestion

Ingestion

Human Receptors: 

Current/ Future

Flow-Chart Continues

Partial / Possible Flow

Flow-Chart Stops

Incomplete Pathway

Potentially Complete Pathway

Complete Pathway

Site 

Worker

Construction 

Worker Resident Trespasser

Site 

Worker

Construction 

Worker Resident Trespasser

/

/ / /

LEGEND

/ / / /

/ / / /

/ / / /

Figure ES-2

Preliminary Conceptual Site Model

Duncan Armory AASF, Delaware

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

Notes:

1. The residential receptor refers to an off-facility 

receptor.

2. Human consumption of agricultural products 

potentially affected by PFAS is possible

/

/ /

4
PFAS Preliminary Assessment Report

Duncan AASF, New Castle, Delaware 

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1. Introduction

 Authority and Purpose

The Army National Guard (ARNG)- Installations & Environment Division is the lead agency in 

performing Preliminary Assessments (PAs) and Site Inspections (SIs) for Perfluoroocatesulfonic 

acid (PFOS) and Perfluorooctanoic acid (PFOA) at Impacted Sites at ARNG Facilities Nationwide.

This work is supported by the United States (US) Army Corps of Engineers (USACE) Baltimore 

District and their contractor AECOM Technical Services, Inc. (AECOM) under Contract Number 

W912DR-12-D-0014, Task Order W912DR17F0192, issued 11 August 2017.

The ARNG is assessing potential effects on human health related to processes at facilities that 

used per- and poly-fluoroalkyl substances (PFAS), primarily in the form of aqueous film forming 

foam (AFFF) released as part of firefighting activities, although other PFAS sources are possible. 

In addition, the ARNG is assessing businesses or operations adjacent to the ARNG facility (not 

under the control of ARNG) that could potentially be responsible for a PFAS release. 

PFAS are classified as emerging environmental contaminants that are garnering increasing 

regulatory interest due to their potential risks to human health and the environment. PFAS 

formulations contain highly diverse mixtures of compounds. Thus, the fate of PFAS compounds 

in the environment varies. The regulatory framework at both federal and state levels continues to 

evolve. The US Environmental Protection Agency (USEPA) issued Drinking Water Health 

Advisories (HA) for PFOA and PFOS in May 2016, but there are currently no promulgated national 

standards regulating PFAS in drinking water. The HA is 70 parts per trillion for PFOS and PFOA, 

individually or combined. 

This report presents the findings of a PA for PFAS-containing materials at Duncan Armory AASF 

(DAASF; also referred to as the “facility”) in New Castle, Delaware, in accordance with the 

Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), as 

amended, the National Oil and Hazardous Substances Pollution Contingency Plan (40 Code of 

Federal Regulations [CFR] Part 300), and Army requirements and guidance. 

This PA documents potential locations where PFAS may have been released into the environment 

at DAASF. The term PFAS will be used throughout this report to encompass all PFAS chemicals 

being evaluated, including PFOS and PFOA, which are key components of AFFF.

Preliminary Assessment Methods

The performance of this PA included the following tasks: 

• Reviewed available administrative record documents and Environmental Data Resources, 

Inc. (EDR)TM report packages to obtain information relevant to potential PFAS releases, such 

as: drinking water well locations, historical aerial photographs, Sanborn maps, and 

environmental compliance actions in the area surrounding the facility;.

• Conducted a site visit on 6 August 2019 and completed visual site inspections (VSIs) at 

locations where PFAS-containing materials were suspected of being stored, used, or 

disposed;

• Interviewed current DAASF personnel including environmental managers and operations 

staff during the site visit; 

• Identified areas of interest (AOIs) and developed a preliminary conceptual site model (CSM) 

to summarize potential PFAS source-pathway-receptor linkages for each AOI. 
PFAS Preliminary Assessment Report

Duncan AASF, New Castle, Delaware 

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Report Organization

This report has been prepared in accordance with the USEPA Guidance for Performing 

Preliminary Assessments under CERCLA (USEPA 1991). The report sections and descriptions of 

each are as follows: 

• Section 1 – Introduction: identifies the project purpose and authority and describes the 

facility location, environmental setting, and methods used to complete the PA. 

• Section 2 – Fire Training Areas: describes the fire training areas (FTAs) at the facility 

identified during the site visit. 

• Section 3 – Non-Fire Training Areas: describes other locations of potential PFAS releases 

at the facility identified during the site visit. 

• Section 4 – Emergency Response Areas: describes areas of potential PFAS release at the 

facility, specifically in response to emergency situations. 

• Section 5 – Adjacent Sources: describes sources of potential PFAS release adjacent to the 

facility that are not under the control of ARNG. 

• Section 6 – Preliminary Conceptual Site Model: describes the pathways of PFAS transport 

and receptors for the AOIs and the facility. 

• Section 7 – Conclusions: summarizes the data findings and presents the conclusions and 

uncertainties of the PA. 

• Section 8 – References: provides the references used to develop this document. 

• Appendix A – Data Resources

• Appendix B – Preliminary Assessment Documentation

• Appendix C – Photographic Log

Facility Location and Description 

DAASF occupies 17.3 acres in New Castle, Delaware (Figure 1-1). The facility is located adjacent 

to New Castle Airport. Delaware’s Air National Guard (ANG) base is across airport taxiways to the

east. The nearest metropolitan area is Wilmington, Delaware, 5.6 miles from the facility. Properties 

surrounding DAASF are primarily zoned for single-family homes and businesses (New Castle 

County Delaware [NCCDE], 2018). 

DAASF is located on a portion of land the Delaware National Guard leased from New Castle 

Airport for a term of 50 years. DAASF has been used as an active military facility since the lease 

signing in 1973. Currently and historically, the facility has been used for aircraft maintenance as 

well as administrative duties. The facility includes an aircraft hangar to house machinery, 

administrative offices, and helicopter landing pads. Directly outside of the facility boundary are 

airport runways and taxiways. Access to the facility is via a guarded gate.

Facility Environmental Setting 

The facility is located in northern New Castle County, Delaware, southwest of Wilmington, 

Delaware and is approximately 64 feet above mean sea level (amsl). Major geographic features 

include the Christina River, which flows generally northeast, into the Delaware River, and is part 

of the Christina River basin reaching into Pennsylvania (Delaware Watersheds). The Delaware 

River flows south to the Delaware Bay. Buildings, asphalt, and concrete cover much of the facility, 

but green space exists around the parking lot and on the southwestern corner of the property 

surrounding the stormwater retention basin. DAASF lies within the Coastal Plain region of 
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Duncan AASF, New Castle, Delaware 

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Delaware, which is composed of variegated silts and clays and is a predominantly low, flat area 

about 100 feet amsl (Figure 1-2). This region of Delaware has two fluvial geologic formations: the 

Columbia and the Potomac (AFW, 2019). The Potomac formation occurs in a fluvial setting in 

tropical to subtropical climates (Delaware Geological Survey [DGS], 2019). 

Little environmental work has been performed at DAASF; therefore, information in the following 

sections has been drawn primarily for the Final Site Inspection Report for the nearby Delaware 

ANG (DANG) in New Castle, Delaware (AFW, 2019). 

1.5.1 Geology

Based on the available data from US Geological Survey (USGS) maps, the facility lies within the 

Coastal Plain Delaware Bay Group (USGS, 2005). Soil type within this group, and subsequently

within the boundary of DAASF, consists of medium to medium-to-coarse sands above fine-tomedium to fine sandy silt (Figure 1-2). The sands of this group are primarily quartzose, with 

varying quantities of feldspar. Deposits in this group are vertically and laterally heterogeneous, 

with an upward fining of sediment texture (DGS, 2019).

1.5.2 Hydrogeology

New Castle County, Delaware has two aquifers: the Columbia and Potomac. The Columbia is the 

surficial aquifer in this area and can either be perched or act as a hydrologic unit with the Potomac 

aquifer. A previous investigation was conducted by the ANG approximately one mile from DAASF. 

Due to the proximity of this study, it is inferred that the geologic information provided is similar to 

that at DAASF. The study indicated that the Columbia formation in this area is predominantly dry, 

with perched water tables present. The Potomac aquifer consists of two independent (Upper and 

Middle), laterally continuous sand bodies within the water-bearing zones of the Potomac 

formation. The water table under normal conditions sits at an elevation of approximately 20 to 30

feet amsl. 

The Upper Potomac Aquifer lies in both the shallow and intermediate groundwater-bearing zones.

The shallow zone extends from 0 to 30 feet amsl, and there is no clear distinction between the 

surficial Columbia aquifer and the Upper Potomac Aquifer. Separated from the shallow zone by a 

semi-confining layer of clay, the intermediate groundwater-bearing zone ranges from 1 to 20 feet 

thick, extends approximately 50 feet below mean sea level (bmsl), and is considered to be part of 

the Upper Potomac aquifer. Results of groundwater elevation data from a previous investigation

at the adjacent ANG facility suggest that the shallow and intermediate zones are interconnected, 

as they show similar trends. The ANG groundwater gauging also determined that groundwater in 

both zones of the Upper Potomac Aquifer as well as the Columbia Aquifer is inferred to flow 

generally to the north (Figure 1-2). 

The Middle Potomac Aquifer is considered the deep groundwater-bearing zone and is separated 

from the Upper Potomac Aquifer by a layer of clay 60 to 80 feet thick; it does not vertically transmit 

water. Below the clay layer, the aquifer’s water-bearing sands extend from 120 to 130 feet bmsl. 

Groundwater levels are about 5 to 10 feet bmsl, suggesting that the groundwater is confined, and

there is little transmission of water vertically between the Upper and Middle Potomac Aquifers. 

Groundwater in the Middle Potomac Aquifer flows to the south-southeast (Figure 1-2). 

In New Castle County, south of the Chesapeake and Delaware Canal, approximately 10 miles 

south of the facility, nearly all drinking water is from groundwater provided by public and private 

wells. However, north of the canal in northern New Castle County, where DAASF is located,

groundwater supplies only 30% of drinking water (DGS, 2019). 

Based on the USEPA Unregulated Contaminant Monitoring Rule 3 data, it was indicated that 

PFAS were detected in a public water system above the HA within 20 miles of the facility
PFAS Preliminary Assessment Report

Duncan AASF, New Castle, Delaware 

8

(Appendix A). The HA is 70 parts per trillion for PFOS and PFOA, individually or combined. PFAS 

analyses performed in 2016 had method detection limits that were higher than currently 

achievable. Thus, it is possible that low concentrations of PFAS were not detected during the 

UCMR3 but might be detected if analyzed today. The Delaware Department of Natural Resources 

and Environmental Control (DNREC) reported that Artesian Water Company, a primary drinking 

water provider in the area, and the City of New Castle Municipal Services Commission detected 

PFAS in public water supply wells in the area of DAASF. The area of contamination is 

approximately 7 square miles and is bounded to the north by Interstate 295, the Delaware River 

to the east, Route 273 to the south, and Route 13 and New Castle Airport to the West. This area 

of PFAS contamination includes New Castle County Airport, DAASF property, and surrounding 

residential areas. The public water supply is treated for PFAS contamination before distribution

(DNREC, 2019); however, there are 8 private domestic groundwater supply wells within 1 mile of 

the facility (EDRTM, 2019). An EDRTM report conducted a well search for a 1-mile radius 

surrounding the facility (Appendix A). Using additional online resources, such as state and local 

geographic information system (GIS) databases, wells were researched to a 4-mile radius of the 

facility. According to data from the state of Delaware, the majority of wells to the southeast of the 

facility, deep groundwater’s downgradient direction, are monitoring wells (Delaware Open Data, 

2020). A 2019 USEPA report figure shows four Artesian public water supply wells located 3 miles 

south of the facility (USEPA, 2019). North of the facility, shallow groundwater’s downgradient 

direction to the Christina River, there are a combination of monitoring and domestic groundwater 

wells. Well locations shown on Figure 1-2 are approximate (Appendix A). 

The adjacent ANG base has undergone an SI for PFAS, and results of the study show HA 

exceedances for PFAS in groundwater and surface water samples (AFW, 2019). Of the 

groundwater sample locations, eight locations had results above the HA, and one of two surface 

water sample locations had results above the HA (AFW, 2019).

1.5.3 Hydrology

North of DAASF is the Christina River, a part of the Christina River Basin that extends from 

Pennsylvania through New Castle County, Delaware. The Christina River Basin is characterized 

by dendritic interconnected rivers, streams, and wetlands, with outflow to the Delaware River

(Figure 1-3). The Christina River is in the southernmost area of the basin and flows northeast, 

into the Delaware River. Surface water accounts for 70% of New Castle County’s water supply.

The majority of which comes from the Christina River Basin, which provides 60% of New Castle 

County’s water overall (NCCDE, 2018). The majority of Christina River is in New Castle County, 

with headwaters in Maryland. The Christina River is tidal from just south of the town of Christiana 

to its convergence with the Delaware River. This section of the Christina lies approximately one 

mile west of the facility and tidal freshwater wetlands occur throughout the area (Delaware 

Watersheds). 

DAASF sits on the Lower Christina River Watershed, at the edge of the Christina Basin, with 

wetlands lying north of the facility. On facility grounds, runoff flows away from the paved areas 

and structures into a retention basin on the southern end of the property, where runoff will infiltrate 

or evaporate. However, surrounding the facility, general surface water flow is north into the 

Christina River and Nonesuch Creek, which converge downstream and continue northeast to the 

Delaware River (Figure 1-3). 

The facility is closest to the 68-mile marker of the Delaware River (Delaware River Basin 

Commission [DRBC], 2011). A presentation from the Delaware River Basin Commission provides 

2009 PFAS concentration data for media tested along the Delaware river. PFAS were detected in 

surface water in the section closest to the facility, between river miles 68 and 70 (DRBC, 2012). 

The 2009 PFOA concentration at river mile 68.1 was 0.0277 micrograms per liter (μg/L), and the

PFOS concentration was 0.00575 μg/L (DRBC, 2012).
PFAS Preliminary Assessment Report

Duncan AASF, New Castle, Delaware 

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1.5.4 Climate 

The climate at DAASF is humid continental. The Delaware Bay and Atlantic Ocean to the east 

and south, and the Chesapeake Bay to the west moderate temperature extremes in the winter 

and summer months. Although the extremes are lessened, the climate at DAASF is still 

continental with hot summers, cold winters, and precipitation throughout the year (AFW, 2019). 

Mean annual temperature in New Castle is 54 degrees Fahrenheit (°F). Average annual high 

temperature for Wilmington, Delaware in New Castle County, is 64.1°F and average annual low 

temperature is 45.8°F. Annual precipitation for Wilmington is approximately 43 inches of rain and 

19 inches of snowfall (US Climate Data, 2019). 

1.5.5 Current and Future Land Use

The DAASF currently resides on a portion of land leased from the New Castle Airport under the 

terms of a 50-year lease. It has been an active military facility since the signing of the lease in 

December 1973. The facility is currently used for aircraft maintenance and administrative 

activities. Future land use is not anticipated to change.
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Facility Location

Base Map: Sources: Esri, HERE, Garmin, USGS,

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

Q:\Projects\ENV\GEARS\GEO\ARNG PFAS\900-CAD-GIS\920-GIS or Graphics\MXD\DE\Duncan_Armory_AASF_Figures\Fig_1-1_Duncan_Armory_AASF_Facility_Location.mxd

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Facility Boundary

^_

Duncan Armory AASF

0 0.5 1 2

Miles

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Groundwater Features

Base Map: Source: Esri, DigitalGlobe, GeoEye,

Earthstar Geographics, CNES/Airbus DS, USDA, USGS,

C:\Users\grace.canham\AECOM Directory\Stankevich, Michael - ARNG_PFAS_GIS_60552172\MXDs\DE\Duncan_Armory_AASF_Figures\Fig_1-2_Duncan_Armory_AASF_Groundwater.mxd

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Water Body

Wetland

River/Stream

Canal/Ditch

Inferred Groundwater Flow

Direction - Shallow Aquifer

Inferred Groundwater Flow

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Surface Water Features

Base Map: Source: Esri, DigitalGlobe, GeoEye,

Earthstar Geographics, CNES/Airbus DS, USDA, USGS,

Q:\Projects\ENV\GEARS\GEO\ARNG PFAS\900-CAD-GIS\920-GIS or Graphics\MXD\DE\Duncan_Armory_AASF_Figures\Fig_1-3_Duncan_Armory_AASF_Surface_Water.mxd

Legend

Facility Boundary

Water Body

Wetland

River/Stream

Canal/Ditch

Pipeline

Surface Water Flow Direction

0 1,000 2,000 4,000

Feet

12
PFAS Preliminary Assessment Report

Duncan AASF, New Castle, Delaware 

13

2. Fire Training Areas

No FTAs were identified within DAASF during the PA through interviews. Firsthand knowledge of 

interviewees reaches back to 1991, and there is no primary source information between 1969, 

the year the Department of Defense (DoD) started using AFFF, and 1990 (Appendix A). 
PFAS Preliminary Assessment Report

Duncan AASF, New Castle, Delaware 

14

3. Non-Fire Training Areas

In addition to FTAs, the PA evaluated areas where PFAS-containing materials may have been 

broadly used, stored, or disposed. This may include buildings with fire suppression systems, paint 

booths, AFFF storage areas, and areas of compliance demonstrations. Information on these 

features obtained during the PA are included in Appendices A and B. One non-FTA where a fire 

suppression system potentially contains AFFF was identified during the PA. A description of the

non-FTA is presented below, and the non-FTA is shown on Figure 3-1. 

 Hangar 

The hangar is located in the center of the DAASF facility; the geographic coordinates are

39°40’57.095”N; 75°39’56.959”W (Figure 3-1). According to interviewees, at the completion of 

construction of the new hangar and administrative wing in 2011, the existing fire suppression 

system in the hangar was retrofitted with a Jet-X 2% high expansion foam concentrate system. 

During retrofitting, the previous system was discharged with an aqueous soap and water solution 

to test functionality before Jet-X was placed in the system. Prior to the installation of the Jet-X 

deluge system, the fire suppression system was equipped with a non-PFAS foam, though 

interviewees do not remember the type, and firsthand interviewee knowledge only extends back 

to 1991. The storage tank for the current deluge system is located inside the fire suppression 

equipment room, which is accessible from outside of the building. The foam deluge system, 

automatic sprinkler system, and dry pipe sprinkler system are all checked on a quarterly basis by 

Allegiant Fire Protection. Though PFAS are not included in the Hazardous Materials Identification 

System Information for Jet-X, the full contents are a trade secret and not disclosed. As a result, 

the ARNG is conservatively operating under the potential for Jet-X to be PFAS-containing. There 

is no suspected release at this location on the DAASF facility. 
Hangar

CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

GC

8/21/2019

8/21/2019

NOTES Preliminary Assessment for PFAS at Duncan Armory AASF, DE

1:3,600

8/21/2019 ­ Figure 3-1 PM RG 8/21/2019

12420 Milestone Center Drive

Germantown, MD 20876

Non-Fire Training Areas

Base Map: Source: Esri, DigitalGlobe, GeoEye,

Earthstar Geographics, CNES/Airbus DS, USDA, USGS,

Q:\Projects\ENV\GEARS\GEO\ARNG PFAS\900-CAD-GIS\920-GIS or Graphics\MXD\DE\Duncan_Armory_AASF_Figures\Fig_3-1_Duncan_Armory_AASF_Non-Fire_Training_Areas.mxd

Legend

No Suspected Release

Facility Boundary

0 150 300 600

Feet

15
PFAS Preliminary Assessment Report

Duncan AASF, New Castle, Delaware 

16

4. Emergency Response Areas

One emergency response area was identified within DAASF during the PA through interviews. A 

description is presented below, and the area is shown on Figure 4-1. 

Helicopter Crash Site

In the 1970s, an ARNG helicopter crashed on the boundary between the DAASF facility and New 

Castle Airport properties; the geographic coordinates are 39°40’53.789”N; 75°36’56.487”W

(Figure 4-1). Interviewees with secondhand knowledge of the event indicated that the municipal 

fire department (FD) responded to the scene using a foam fire suppressant. It is unknown whether 

the aqueous foam used was AFFF. The released foam likely followed on-site surface water 

pathways to the retention basin at the southern end of the facility. Surface water runoff from the 

facility collects in this basin until it evaporates or infiltrates the subsurface. The crash location is 

a potential PFAS release.
Helicopter Crash Site

(Municipal FD Response)

CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

GC

11/1/2019

11/1/2019

NOTES Preliminary Assessment for PFAS at Duncan Armory AASF, DE

1:3,600

11/1/2019 ­ Figure 4-1

PM RG 11/1/2019

12420 Milestone Center Drive

Germantown, MD 20876

Emergency Response Area

Base Map: Source: Esri, DigitalGlobe, GeoEye,

Earthstar Geographics, CNES/Airbus DS, USDA, USGS,

Q:\Projects\ENV\GEARS\GEO\ARNG PFAS\900-CAD-GIS\920-GIS or Graphics\MXD\DE\Duncan_Armory_AASF_Figures\Fig_4-1_Duncan_Armory_AASF_Emergency_Response.mxd

Legend

Potential PFAS Release

Facility Boundary

0 150 300 600

Feet

17
PFAS Preliminary Assessment Report

Duncan AASF, New Castle, Delaware 

18

5. Adjacent Sources

Five potential off-facility sources of PFAS located adjacent to DAASF, not under the control of 

ARNG, were identified during the PA through interviews and news reports. A description of each 

adjacent source is presented below, and the adjacent sources are shown on Figure 5-1. 

Delaware Auto Salvage Fire

In July 2018, a fire of unknown origin broke out at Delaware Auto Salvage, located approximately 

1.3 miles from DAASF. Emergency response units were called from surrounding cities to assist in 

controlling the fire. It was estimated that nearly 400 vehicles ignited, and news agencies reported 

that water was used to control the flames. This location has no suspected PFAS release because 

there are no reports or interviewee accounts of foam being used to control the fire (ABC, 2018). 

Emergency response personnel were not interviewed during the PA because the focus of the 

assessment was to evaluate potential PFAS related activities and sources at Delaware ARNG

(DEARNG) properties. Figure 5-1 shows the location of the Delaware Auto Salvage Fire.

Delaware State Fire School 

Approximately 0.5 miles north of the facility is the Delaware State Fire School New Castle. 

Activities on this campus include exercises with live fires and firefighting foam. The type of foam 

used is uncertain, but there is a potential for PFAS release at this location. Delaware State Fire 

School personnel were not interviewed during the PA because the focus of the assessment was 

to evaluate potential PFAS related activities and sources at DEARNG properties. Figure 5-1

shows the location of the Delaware State Fire School.

Aircraft Crash Site

In June 1991, a military aircraft tilted while on a test flight, and its wing hit the ground, igniting a 

small fire which was then extinguished by the DANG FD. It is unknown whether AFFF were used 

to extinguish the fire; however, the DANG FD is known to use AFFF for fire suppression. Because 

the use of AFFF at the crash site cannot be confirmed, the crash site has been identified as a 

potential PFAS release area. DANG personnel were not interviewed during the PA because the 

focus of the assessment was to evaluate potential PFAS related activities and sources at 

DEARNG properties. Figure 5-1 shows the location of the Aircraft Crash.

DANG Fire Training Area

Approximately 80 feet southwest of the southwestern corner of DAASF property is the location of 

DANG’s FTA. This location is DANG’s current operational FTA. Interviewees noted training with 

fire suppressing foam does occur on this site, but they are unsure whether the foam is AFFF. 

Because of this uncertainty, the DANG FTA has been identified as a potential PFAS release area. 

DANG personnel were not interviewed during the PA because the focus of the assessment was 

to evaluate potential PFAS related activities and sources at DEARNG properties. Figure 5-1

shows the location of the DANG FTA. 

Airplane Crash Site

In November of 2018, a crash was reported at the adjacent ANG base. According to interviews 

and news reports, the aircraft’s landing gear malfunctioned, causing it to land nose-gear up with 

no anterior wheel. No action from emergency response units present was required, as the airplane 

came to an abrupt halt with no fires igniting and only minimal sparking. Due to no emergency 

action being necessary, this area has been identified as a location with no suspected PFAS 

release.
Airplane

Crash

Delaware Auto

Salvage Fire

DANG Fire

Training

Aircraft

Crash

State of Delaware

Fire Training

CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

GC

9/27/2019

9/27/2019

NOTES Preliminary Assessment for PFAS at Duncan Armory AASF, DE

1:14,400

9/27/2019 ­ Figure 5-1

PM RG 9/27/2019

12420 Milestone Center Drive

Germantown, MD 20876

Adjacent Sources

Base Map: Source: Esri, DigitalGlobe, GeoEye,

Earthstar Geographics, CNES/Airbus DS, USDA, USGS,

Q:\Projects\ENV\GEARS\GEO\ARNG PFAS\900-CAD-GIS\920-GIS or Graphics\MXD\DE\Duncan_Armory_AASF_Figures\Fig_5-1_Duncan_Armory_AASF_Adjacent_Sources.mxd

Legend

Potential PFAS Release

No Suspected Release

Facility Boundary

Water Body

Wetland

River/Stream

0 600 1,200 2,400

Feet

19
PFAS Preliminary Assessment Report

Duncan AASF, New Castle, Delaware 

20

6. Preliminary Conceptual Site Model

Based on the PA findings, one AOI was identified at DAASF: AOI 1 is the helicopter crash site and 

foam drainage pathway. The AOI location is shown on Figure 6-1. The following sections describe 

the CSM components and the specific preliminary CSM developed for AOI 1. The CSM identifies 

the three components necessary for a potentially complete exposure pathway: (1) source, (2) 

pathway, (3) receptor. If any of these elements are missing, the pathway is considered incomplete.

In general, the potential PFAS exposure pathways 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 is sparse and 

continues to be the subject of PFAS toxicological study. Receptors at DAASF include site workers, 

construction workers, trespassers, and off-site residents. The preliminary CSM for DAASF 

indicates which specific receptors could potentially be exposed to PFAS (Figure 6-2).

AOI 1 Helicopter Crash Site

AOI 1 consists of the general location of the 1970s ARNG helicopter crash site, including the

runoff path and retention basin where AFFF may have accumulated. Historical knowledge from 

interviews suggests the municipal FD responded to the scene and used foam to suppress the fire.

Though the type of foam used is unknown, the municipal FD is known to use AFFF to extinguish

fires.

If used, residual fire-fighting foam may have flowed via the surface water drainage ditch from the 

crash site to the retention basin in the southwest corner of the facility. Ingestion of surface water 

or sediments is possible along the drainage path from the crash site as well as the retention basin, 

considering the foam likely settled there. As a result, there are potentially complete surface water 

and sediment pathways for site workers, construction workers, and trespassers. Exposure to 

PFAS via inhalation of airborne soil particulates and ingestion of surface soil may occur at this 

facility, as contaminated runoff from the crash site likely would have migrated across both paved 

and unpaved areas on route to the retention basin. Site workers, construction workers, and 

trespassers may be exposed to soil across this area. PFAS contamination of subsurface soil and

shallow groundwater may have occurred, as PFAS can infiltrate subsurface soil and leach into

groundwater. PFAS exposure to construction workers via subsurface soil is potentially complete. 

PFAS contamination from the potential source area may have infiltrated to groundwater from the 

retention basin and along the path of foam migration from the crash site. Shallow groundwater is 

inferred to flow north, towards the Christina River, and deep groundwater is inferred to flow 

southeast, towards the Delaware River. While no potable water wells are located within DAASF, 

there are public water supply wells within 3.5 miles of the facility, located in the Public Wells 

Groundwater Plume Site. The approximate locations of the public wells were included in a 2019

EPA report and found to be south of the facility. DNREC’s community fact sheet in Appendix A

provides an outlined area of the Public Wells Groundwater Plume Site that encompasses the area 

of these four public wells. This public well plume site, as described previously, encompasses the 

New Castle County Airport, DAASF property, and surrounding residential areas (DNREC, 2019).

These public wells are treated for PFAS contamination by Artesian Water Company, Inc. 

The EDRTM report indicates there are also eight domestic, private wells that are located within 1 

mile of the facility (EDRTM, 2019). A potentially complete groundwater ingestion pathway exists for 

off-facility residents using these private wells. The ingestion pathway for groundwater to

construction workers is also potentially complete. The preliminary CSM for AOI 1 is shown on 

Figure 6-2. 
Airplane

Crash

Hangar

Middle

Christina River

Watershed

Lower Christina

River Watershed

Army Creek-Frontal

Delaware River

Watershed

DANG Fire

Training

Aircraft

Crash

Helicopter Crash Site

(Municipal FD Response)

AOI 1

CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

GC

1/9/2020

1/9/2020

NOTES Preliminary Assessment for PFAS at Duncan Armory AASF, DE

1:7,200

1/9/2020 ­ Figure 6-1

PM RG 1/9/2020

12420 Milestone Center Drive

Germantown, MD 20876

Area of Interest

Base Map: Source: Esri, DigitalGlobe, GeoEye,

Earthstar Geographics, CNES/Airbus DS, USDA, USGS,

Q:\Projects\ENV\GEARS\GEO\ARNG PFAS\900-CAD-GIS\920-GIS or Graphics\MXD\DE\Duncan_Armory_AASF_Figures\Fig_6-1_Duncan_Armory_AASF_AOIs.mxd

Legend

Area of Interest

Potential PFAS Release

No Suspected Release

Facility Boundary

Water Body

Wetland

River/Stream

Surface Water Flow

Direction

Inferred Groundwater Flow

Direction - Shallow Aquifer

Inferred Groundwater Flow

Direction - Deep Aquifer

0 300 600 1,200

Feet

21
Media

SOURCE PATHWAY RECEPTOR

AOI1

Emergency 

Response to 

Helicopter Crash

PFAS in 

Surface Soil 

and Paved 

Tarmac

Human 

Activities

Precipitation/ 

Run-Off

Leaching/ 

Infiltration

Airborne Soil 

particulate

Surface Soil 

at AOI

Surface 

Water/ 

sediment

Subsurface 

Soil

Shallow 

Groundwater

Source Release 

Mechanism Media Transport and Migration Media Exposure Routes

Inhalation of 

Dust

Ingestion

Ingestion

Ingestion

Ingestion

Human Receptors: 

Current/ Future

Flow-Chart Continues

Partial / Possible Flow

Flow-Chart Stops

Incomplete Pathway

Potentially Complete Pathway

Complete Pathway

Site 

Worker

Construction 

Worker Resident Trespasser

Site 

Worker

Construction 

Worker Resident Trespasser

/

/ / /

LEGEND

/ / / /

/ / / /

/ / / /

Figure 6-2

Preliminary Conceptual Site Model

Duncan Armory AASF, Delaware

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

Notes:

1. The residential receptor refers to an off-facility 

receptor.

2. Human consumption of agricultural products 

potentially affected by PFAS is possible

/

/ / /

22
PFAS Preliminary Assessment Report

Duncan AASF, New Castle, Delaware 

23

7. Conclusions

This report presents a summary of available information gathered during the PA on the use of 

AFFF at DAASF. The PA findings are based on the information presented in Appendix A and 

Appendix B. 

 Findings 

One AOI related to potential PFAS release (Table 7-1) was identified at DAASF during the PA

through interviews with facility personnel (Figure 7-1). 

Table 7-1 AOIs at DAASF

Area of Interest Name Used by Potential Release 

Dates

AOI 1 Helicopter Crash Municipal FD 1970s

Based on a potential PFAS release at the AOI, there is potential for exposure to PFAS 

contamination in airborne soil particulates, surface soil, surface water and sediments to site 

workers, construction workers, and trespassers via ingestion and inhalation; subsurface soil to 

construction workers via ingestion; and groundwater to construction workers and off-facility 

residents. 

The following areas shown in Table 7-2 and discussed in Section 3 were determined to have no 

suspected release.

Table 7-2 No Suspected Release Areas

No Suspected Release 

Area Used by Rationale for No Suspected Release Determination

Hangar DAASF 

The fire suppression system has not been 

discharged since it was retrofitted with Jet-X, 

a potentially PFAS-containing foam.

Several adjacent sources of PFAS exist near DAASF. These sources include the location of 

DANG’s FTA as well as the State of Delaware Fire Training School. Both FTAs are known to use 

fire-suppressing foam in exercises that may include AFFF. Excess foam could travel downgradient 

from DANG property to the retention basin at DAASF. The aircraft crash is another potential offfacility source of PFAS. If AFFF was used to suppress the fire at this location, PFAS could have 

traveled via runoff or groundwater flow onto DAASF property.

 Uncertainties 

A number of information sources were investigated during this PA to determine the potential for 

PFAS-containing materials to have been present, used, or released at the facility. Historically, 

documentation of PFAS use was not required because PFAS were considered benign. Therefore, 

records were not typically kept by the facility or available during the PA on the use of PFAS in 

training, firefighting, or other non-traditional activities, or on its disposition. 

The conclusions of this PA are based on all available information, including: previous 

environmental reports, EDRsTM, observations made during the VSI, and interviews. Interviews of 

personnel with direct knowledge of a facility generally provided the most useful insights regarding 

a facility’s historical and current PFAS-containing materials. Sometimes, the provided information 
PFAS Preliminary Assessment Report

Duncan AASF, New Castle, Delaware 

24

was vague. Gathered information has a degree of uncertainty due to the absence of written 

documentation, the limited number of personnel with direct knowledge due to staffing changes, 

the time passed since PFAS were first used (1969 to present), and a reliance on personal 

recollection. Inaccuracies may arise in potential PFAS release locations, dates of release, volume 

of releases, and the concentration of AFFF used. There is also a possibility the PA has missed a 

source of PFAS, as the science of how PFAS may enter the environment continually evolves.

In order to minimize the level of uncertainty, readily available data regarding the use and storage 

of PFAS were reviewed, retired and current personnel were interviewed, multiple persons were 

interviewed for the same potential source area, and potential source areas were visually 

inspected. Table 7-3 summarizes the uncertainties associated with the PA.

Table 7-3 Uncertainties

Area of Interest Source of Uncertainty

AOI 1: Helicopter Crash

Due to the date of the crash and staffing turnover, it is not 

known what type, quantity, or concentration of foam was used 

at the crash location, nor the exact year of the crash. The 

firefighting foam used could potentially have been AFFF.

General

A data gap exists between 1969 (when DoD began using 

AFFF) and 1991. Firsthand knowledge of activities that 

occurred at DAASF dates back to 1991.

General

Due to trade secrets, the full contents of Jet-X foam, used in 

the hangar’s fire suppression system, are unknown and could

contain PFAS.

It is also unknown whether or to what degree the potential adjacent off-facility PFAS release areas

associated with the DANG Base or the New Castle Airport may affect DAASF. 

Potential Future Actions

Based on the absence (1991-present) of the release of PFAS-containing materials in the hangar,

evidence does not indicate that current or former DEARNG activities in this area contributed PFAS 

contamination to soil, groundwater, surface water, or sediment at DAASF. This area will not move 

forward in the CERCLA process.

Interviews (covering 1990s to present) indicate that emergency response activities associated 

with the AOI may have introduced PFAS into the environment, thus, there is potential for receptors 

to be exposed to PFAS as shown in the preliminary CSM in Section 6. Table 7-4 summarizes the 

rationale used to determine if the AOI should be considered for further investigation under the 

CERCLA process and undergo an SI. 

ARNG will evaluate the need for an SI at DAASF based on the potential receptors, the potential 

migration of PFAS contamination off the facility, and the availability of resources. 
PFAS Preliminary Assessment Report

Duncan AASF, New Castle, Delaware 

25

Table 7-4 PA Findings Summary

Area of 

Interest AOI Location Rationale 

Potential Future 

Action

AOI 1

Helicopter 

Crash

39°40'53.30"N; 

75°36'55.79"W 

The helicopter crash fire was 

contained with an unknown foam, 

and residual foam may have been 

released to the ground and 

migrated to the retention basin onsite.

Proceed to an SI, 

focus on soil, 

surface water, 

sediment, and 

groundwater
Christina River

Airplane

Crash

Hangar

DANG Fire

Training

Aircraft

Crash

State of Delaware

Fire Training

Helicopter

Crash Site

AOI 1

CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

GC

10/8/2019

10/8/2019

NOTES Preliminary Assessment for PFAS at Duncan Armory AASF, DE

1:7,200

10/8/2019 ­ Figure 7-1

PM RG 10/8/2019

12420 Milestone Center Drive

Germantown, MD 20876

Summary of Findings

Base Map: Source: Esri, DigitalGlobe, GeoEye,

Earthstar Geographics, CNES/Airbus DS, USDA, USGS,

Q:\Projects\ENV\GEARS\GEO\ARNG PFAS\900-CAD-GIS\920-GIS or Graphics\MXD\DE\Duncan_Armory_AASF_Figures\Fig_7-1_Duncan_Armory_AASF_Summary.mxd

Legend

Area of Interest

Potential PFAS Release

No Suspected Release

Facility Boundary

Water Body

Wetland

River/Stream

0 300 600 1,200

Feet

26
PFAS Preliminary Assessment Report

Duncan AASF, New Castle, Delaware 

27

8. References

ABC 6 Action News (ABC). 2018. Hundreds of vehicles caught fire at Delaware salvage yard.

https://6abc.com/hundreds-of-vehicles-caught-fire-at-delaware-salvage-yard/3802229/

Amec Foster Wheeler (AFW). 2019. Final Report FY16 Phase 1 Regional Site Inspections for 

Per and Poly Fluoralkyl Substances Volume I of XII.

Delaware Department of Natural Resources and Environmental Control (DNREC). New castle 

County Airport Area Community Fact Sheet. (Accessed September 2019). 

http://www.dnrec.delaware.gov/dwhs/SIRB/Documents 

Delaware Geological Survey (DGS). 2019. Hydrologic Information for Delaware. (Accessed 

September 2019). https://www.dgs.udel.edu/water-resources

Delaware Geological Survey (DGS). 2019. Potomac Formation. (Accessed August 2019). 

https://www.dgs.udel.edu/delaware-geology/unit/potomac-formation

Delaware Geological Survey (DGS). 2019. Delaware Bay Group. (Accessed October 8, 2019) 

https://www.dgs.udel.edu/delaware-geology/unit/delaware-bay-group

Delaware Open Data. 2020. Well Permits – Energy and Environment. (Accessed June 11, 

2020). https://data.delaware.gov/Energy-and-Environment/Well-Permits/2655-qn8j

Delaware River Basin Commission (DRBC). 2012. Contaminants of Emerging Concern in the 

Tidal Delaware River. (Accessed November 1, 2019).

https://www.nj.gov/drbc/library/documents/contaminants-of-emergingconcernAug2013rev.pdf

Delaware River Basin Commission (DRBC). 2011. River Mileage System. (Accessed November 

11, 2019). https://www.state.nj.us/drbc/basin/river/

Delaware Watersheds. Christina River. (Accessed August 2019).

http://delawarewatersheds.org/piedmont/christina-river/

Environmental Data Resources, Inc. (EDR)TM, 2019. The EDRTM Radius Map Report with 

GeoCheck. 

New Castle County Delaware Government (NCCDE). 2018. Zoning Map Index. (Accessed 

September 2019). http://zoningmaps.nccde.org/

U.S. Climate Data. 2019. Climate Wilmington – Delaware. (Accessed August 2019). 

https://www.usclimatedata.com/climate/wilmington/delaware/united-states/usde0055

U.S. Environmental Protection Agency (USEPA). September 2019. Fifth Five-Year Review 

Report for Army Creek Landfill Superfund Site New Castle Couny, Delaware. (Accessed 

February 2019). https://semspub.epa.gov/work/03/2282857.pdf

U.S. Environmental Protection Agency (USEPA), 1991. Guidance for Performing Preliminary 

Assessments under CERCLA. EPA/540/G91/013. 

U.S. Geological Survey (USGS). 2005. Geologic Map of New Castle County, Delaware. 

(Accessed October 8, 2019). https://www.dgs.udel.edu/datasets/dgs-geologic-map-no13-new-castle-county-dataset
PFAS Preliminary Assessment Report

Duncan AASF, New Castle, Delaware

Appendix A 

Data Resources
Data Resources will be provided separately on CD. Data Resources for Duncan Armory AASF

includes:

Duncan AASF Previous Site Investigations

· 2019, Final Report FY16 Phase 1 Regional Site Inspections for Perfluorinated

Compounds, Amec Foster Wheeler

· Delaware Department of Natural Resources and Environmental Control’s New Castle

County Airport Area Fact Sheet, PFOS/PFOA Detected in Ground Water from New

Castle Public Wells

Duncan AASF Site Background Documents

· 2005, USGS Geologic Map of New Castle County, Delaware, Kelvin W. Ramsey

· 2019, Hoopes Fire Prevention, Inc. & Allegiant Fire Protection Inspection Notes

· 2017, Jet-X 2% High Expansion Foam Concentrate Data Sheet

· 2013, Contaminants of Emerging Concern in the Tidal Delaware River: Pilot Monitoring

Survey 2007-2009

· 2019, Fifth Five-Year Review Report for Army Creek Landfill Superfund Site New Castle

County, Delaware

Duncan AASF Site Property Documents

· 1973, Duncan Army Aviation Support Facility Lease Agreement

Environmental Data Resources Reports, Inc.TM

· 2019, Aerial Photo Decade Package, Environmental Data Resources, Inc.TM

· 2019, Certified Sanborn Map Report, Environmental Data Resources, Inc.TM

· 2019, Radius Map Report with Geocheck, Environmental Data Resources, Inc.TM
PFAS Preliminary Assessment Report

Duncan AASF, New Castle, Delaware

Appendix B 

Preliminary Assessment Documentation
PFAS Preliminary Assessment Report

Duncan AASF, New Castle, Delaware

Appendix B.1 

Interview Records







PFAS Preliminary Assessment Report

Duncan AASF, New Castle, Delaware

Appendix B.2 

Visual Site Inspection Checklists




PFAS Preliminary Assessment Report

Duncan AASF, New Castle, Delaware

Appendix B.3 

Conceptual Site Model Information



PFAS Preliminary Assessment Report

Duncan AASF, New Castle, Delaware

Appendix C 

Photographic Log
Preliminary Assessment Report

Duncan Armory AASF

Perfluorooctane-Sulfonic Acid (PFOS) and 

Perfluorooctanoic Acid (PFOA) Impacted Sites

ARNG Installations, Nationwide

APPENDIX C – Photographic Log

Army National Guard, Preliminary 

Assessment for PFAS Duncan Armory AASF New Castle, Delaware

Photograph No. 1

Description:

Duncan AASF AFFF fire 

suppression system fans 

Photo Date: 8/6/2019 

Photograph No. 2

Description:

AFFF foam suppression 

system activation switch.

Photo Date: 8/6/2019 
Preliminary Assessment Report

Duncan Armory AASF

Perfluorooctane-Sulfonic Acid (PFOS) and 

Perfluorooctanoic Acid (PFOA) Impacted Sites

ARNG Installations, Nationwide

APPENDIX C – Photographic Log

Army National Guard, Preliminary 

Assessment for PFAS Duncan Armory AASF New Castle, Delaware

Photograph No. 3

Description:

Tank housed in Fire 

Suppression Room. Possible 

AFFF fluid for fire 

suppression system. 

Photo Date: 12/9/2019 

Photograph No. 4

 

Description:

Images of Jet-X tank labels

Photo Date: 12/9/2019 
Preliminary Assessment Report

Duncan Armory AASF

Perfluorooctane-Sulfonic Acid (PFOS) and 

Perfluorooctanoic Acid (PFOA) Impacted Sites

ARNG Installations, Nationwide

APPENDIX C – Photographic Log

Army National Guard, Preliminary 

Assessment for PFAS Duncan Armory AASF New Castle, Delaware

Photograph No. 5

Description:

Image of informational 

placard on Jet-X tank.

Photo Date: 12/9/2019 

Photograph No. 6

Description:

Image of handheld ABC fire 

extinguisher identical to others 

posted throughout the 

installation.

Photo Date: 8/6/2019
Preliminary Assessment Report

Duncan Armory AASF

Perfluorooctane-Sulfonic Acid (PFOS) and 

Perfluorooctanoic Acid (PFOA) Impacted Sites

ARNG Installations, Nationwide

APPENDIX C – Photographic Log

Army National Guard, Preliminary 

Assessment for PFAS Duncan Armory AASF New Castle, Delaware

Photograph No. 7

Description:

Inspection tag from handheld 

ABC fire extinguisher in 

facility.

Photo Date: 8/6/2019