FINAL

Site Inspection Report 

Morrisville Army Aviation 

Support Facility #1, North 

Carolina

Site Inspection for Perfluorooctanoic acid (PFOA), 

Perfluorooctanesulfonic acid (PFOS), Perfluorohexanesulfonic 

acid (PFHxS), Perfluorononanoic acid (PFNA), 

Hexafluoropropylene oxide dimer acid (HFPO-DA), and 

Perfluorobutanesulfonic acid (PFBS) at ARNG Installations, 

Nationwide 

August 2023 

Prepared for:

Army National Guard Bureau

111 S. George Mason Drive

Arlington, VA 22204

UNCLASSIFIED
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Table of Contents

Executive Summary ..............................................................................................................ES-1

1. Introduction ..................................................................................................................1-1

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

1.2 SI Purpose ............................................................................................................1-1

2. Facility Background ......................................................................................................2-1

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

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

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

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

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

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

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

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

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

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

3.1 AOI 1 Wash Rack and GSE Building .....................................................................3-1

3.2 AOI 2 Delta Row FTA............................................................................................3-1

3.3 AOI 3 Firehouse AFFF Storage and Flush Area ....................................................3-2

3.4 AOI 4 Hangar........................................................................................................3-2

3.5 AOI 5 Long-Term Tri-Max 30TM Storage Area ........................................................3-2

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

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

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

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

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

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

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

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

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

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

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

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

5.3 Permanent Well Installation and Groundwater Sampling.......................................5-3

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

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

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

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

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

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

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

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

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

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

6.3.2 AOI 1 Groundwater Analytical Results.........................................................6-2
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6.3.3 AOI 1 Conclusions ......................................................................................6-3

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

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

6.4.2 AOI 2 Groundwater Analytical Results.........................................................6-4

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

6.5 AOI 3.....................................................................................................................6-4

6.5.1 AOI 3 Soil Analytical Results .......................................................................6-4

6.5.2 AOI 3 Groundwater Analytical Results.........................................................6-5

6.5.3 AOI 3 Conclusions ......................................................................................6-5

6.6 AOI 4.....................................................................................................................6-5

6.6.1 AOI 4 Soil Analytical Results .......................................................................6-5

6.6.2 AOI 4 Groundwater Analytical Results.........................................................6-6

6.6.3 AOI 4 Conclusions ......................................................................................6-6

6.7 AOI 5.....................................................................................................................6-6

6.7.1 AOI 5 Soil Analytical Results .......................................................................6-6

6.7.2 AOI 5 Groundwater Analytical Results.........................................................6-7

6.7.3 AOI 5 Conclusions ......................................................................................6-7

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

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

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

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

7.1.3 AOI 3...........................................................................................................7-2

7.1.4 AOI 4...........................................................................................................7-2

7.1.5 AOI 5...........................................................................................................7-2

7.2 Groundwater Exposure Pathway...........................................................................7-3

7.2.1 AOI 1...........................................................................................................7-3

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

7.2.3 AOI 3...........................................................................................................7-3

7.2.4 AOI 4...........................................................................................................7-4

7.2.5 AOI 5...........................................................................................................7-4

7.3 Surface Water and Sediment Exposure Pathway ..................................................7-4

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

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

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

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

Appendix A Data Usability Assessment and Validation Reports

Appendix B Field Documentation

B1. Log of Daily Notice of Field Activities

B2. Sampling Forms

B3. Well Development Forms

B4. Survey Data

Appendix C Photographic Log

Appendix D TPP Meeting Minutes

Appendix E Boring Logs and Well Construction Forms 

Appendix F Analytical Results

Appendix G Laboratory Reports

Figures

Figure 2-1 Facility Location

Figure 2-2 Facility Topography

Figure 2-3 Groundwater Features

Figure 2-4 Groundwater Elevations, December 2021

Figure 2-5 Surface Water Features

Figure 3-1 Areas of Interest

Figure 5-1 Site Inspection Sample Locations

Figure 6-1 PFOA Detections in Soil

Figure 6-2 PFOS Detections in Soil

Figure 6-3 PFBS Detections in Soil

Figure 6-4 PFHxS Detections in Soil

Figure 6-5 PFNA Detections in Soil

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

Figure 6-7 PFHxS and PFNA Detections in Groundwater

Figure 7-1 Conceptual Site Model - AOI 1 and AOI 3

Figure 7-2 Conceptual Site Model - AOI 2

Figure 7-3 Conceptual Site Model - AOI 4 and AOI 5

Tables

Table ES-1 Screening Levels (Soil and Groundwater)

Table ES-2 Summary of Site Inspection Findings and Recommendations

Table 5-1 Site Inspection Samples by Medium

Table 5-2 Soil Boring Depths, Permanent Monitoring Well Screen Intervals, and 

Groundwater Elevations

Table 6-1 Screening Levels (Soil and Groundwater)

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

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

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

Table 8-1 Summary of Site Inspection Findings and Recommendations
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Acronyms and Abbreviations

% percent

°F degrees Fahrenheit

μg/kg micrograms per kilogram

AASF Army Aviation Support Facility

AECOM AECOM Technical Services, Inc.

AFFF aqueous film forming foam

AOI Area of Interest

ARNG Army National Guard

bgs below ground surface 

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act 

CoC chain of custody

CSM conceptual site model

DA Department of the Army

DoD Department of Defense

DPS Department of Public Safety

DQO data quality objective

DUA data usability assessment

EA EA Engineering, Science, and Technology, Inc. 

ELAP Environmental Laboratory Accreditation Program

EM Engineer Manual

FedEx Federal Express

FTA Fire Training Area

GSE ground support equipment

GPRS Ground Penetrating Radar Systems

HDPE high-density polyethylene 

HFPO-DA hexafluoropropylene oxide dimer acid

IDW investigation-derived waste

ITRC Interstate Technology Regulatory Council

LC/MS/MS liquid chromatography with tandem mass spectrometry

MIL-SPEC military specification

MS matrix spike

MSD matrix spike duplicate

NELAP National Environmental Laboratory Accreditation Program

ng/L nanograms per liter

NCARNG North Carolina Army National Guard 

NCDEQ North Carolina Department of Environmental Quality 

NCWRF North Cary Water Reclamation Facility

OSD Office of the Secretary of Defense

PA Preliminary Assessment

PFAS per- and polyfluoroalkyl substances

PFBS perfluorobutanesulfonic acid

PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid
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PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

PID photoionization detector

PQAPP Programmatic UFP-QAPP

QA quality assurance

QAPP Quality Assurance Project Plan

QC quality control

QSM Quality Systems Manual

RDU Raleigh-Durham International Airport

RI Remedial Investigation

SDO stormwater discharge outfall

SI Site Inspection

SL screening level

SOP standard operating procedure

TOC total organic carbon

TPP Technical Project Planning

UFP Uniform Federal Policy

US United States

USACE United States Army Corps of Engineers

USCS Unified Soil Classification System

USEPA United States Environmental Protection Agency

USFWS United States Fish and Wildlife Service

USGS United States Geological Survey
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Executive Summary

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

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

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

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

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

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

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

, and perfluorobutanesulfonic acid 

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

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

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

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

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

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

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

compounds. This SI was completed at the Morrisville Army Aviation Support Facility (AASF) #1 in 

North Carolina and determined further evaluation under the Comprehensive Environmental 

Response, Compensation, and Liability Act (CERCLA) is warranted for AOI 1, AOI 2, AOI 3, AOI 

4, and AOI 5. The Morrisville AASF #1 will also be referred to as the “facility” throughout this 

document. 

Morrisville AASF #1 is adjacent to Raleigh-Durham International Airport in Morrisville, North 

Carolina. The facility is approximately 34 acres located in in Wake County, North Carolina, 

approximately 10 miles northwest from Raleigh and 10 miles southeast of Durham. The facility 

supports aircraft operations for the North Carolina ARNG (NCARNG). The facility is on North 

Carolina state property, which is controlled and operated by the Department of Public Safety 

(DPS); the NCARNG is a division within the DPS, and the facility is accessible from the main gate 

located along National Guard Drive. 

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

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

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

(RI) for AOI 1, AOI 2, AOI 3, AOI 4, and AOI 5. 

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

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

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

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

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

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

Analyteb

Residential

(Soil)

(μg/kg)a 

0-2 feet bgs

Industrial/ Commercial 

Composite Worker

(Soil)

(μg/kg)a 

2-15 feet bgs

Tap Water

(Groundwater)

(ng/L)a

PFOA 19 250 6

PFOS 13 160 4 

PFBS 1,900 25,000 601 

PFHxS 130 1,600 39

PFNA 19 250 6

Notes:

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

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

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

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

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

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

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

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

AOI

Potential 

Release 

Area

Soil – 

Source Area

Groundwater – 

Source Area

Groundwater –

Facility 

Boundary

Future Action

1

Wash Rack 

Area and 

GSE 

Building

Proceed to RI 

2 Delta Row 

FTA Proceed to RI

3

Firehouse 

Storage and 

Flush Area

Proceed to RI

4 Hangar Leak 

Area N/A Proceed to RI

5 

Long-Term 

Tri-Max 30TM

Storage Area

N/A Proceed to RI

Legend:

N/A = not applicable 

= detected; exceedance of the screening levels

= detected; no exceedance of the screening levels

= not detected 

1 
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1. Introduction

1.1 Project Authorization

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

(PAs) and Site Inspections (SIs) on the current or potential historical use of per- and 

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

memorandum from the Office of the Secretary of Defense (OSD) dated 6 July 2022 (Assistant 

Secretary of Defense, 2022). The six compounds listed in the OSD memorandum will be referred 

to as “relevant compounds” throughout this document and include perfluorooctanoic acid (PFOA), 

perfluorooctanesulfonic acid (PFOS), perfluorohexanesulfonic acid (PFHxS), perfluorononanoic 

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

, and perfluorobutanesulfonic 

acid (PFBS) at ARNG facilities nationwide. The ARNG performed this SI at the Morrisville Army 

Aviation Support Facility (AASF) #1 in North Carolina. The Morrisville AASF #1 is also referred to 

as the “facility” throughout this document. 

The SI project elements were performed in compliance with Comprehensive Environmental 

Response, Compensation, and Liability Act (CERCLA; United States [US] Environmental 

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

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

compliance with US Department of the Army (DA) requirements and guidance for field 

investigations. 

1.2 SI Purpose

A PA was performed at Morrisville AASF #1 (AECOM Technical Services, Inc. [AECOM], 2020) 

that identified fiveAreas of Interest (AOIs) where PFAS-containing materials may have been used, 

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

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

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

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

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

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

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

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

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

individual chemical of concern in the absence of other PFAS.
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2. Facility Background

2.1 Facility Location and Description

Morrisville AASF #1 is adjacent to Raleigh-Durham International Airport (RDU) in Morrisville, North 

Carolina. The facility is approximately 34 acres and resides in Wake County, North Carolina, 

approximately 10 miles northwest from Raleigh and 10 miles southeast of Durham (Figure 2-1). 

The facility was opened in 1988 for the purpose of supporting rotary aircraft operations for the 

North Carolina ARNG (NCARNG). The facility is on North Carolina state property, which is 

controlled and operated by the Department of Public Safety (DPS); the NCARNG is a division 

within the DPS, and the facility is accessible from the main gate located along National Guard 

Drive. The Airport Joint Services Agreement establishes that the RDU Crash Rescue Unit is 

responsible for all fire protection of tenants and users of the airport. The Morrisville AASF #1 fire 

department, known as the 677th Engineer Firefighting Team, is only responsible for the parcel of 

land leased to the NCARNG, and they have a direct line to the RDU Crash Rescue Unit to call for 

emergency aid if needed. 

2.2 Facility Environmental Setting

Morrisville AASF #1 is next to the southeast portion of RDU. The facility property lies within the 

eastern Piedmont physiographic region, which is characterized by rolling hill topography with 

moderately well-drained Creedmoor sandy loam soil (Cawthorn, 1970) (Figure 2-2). The facility 

borders William B. Umstead State Park, which is made up of over 5,500 acres of densely wooded 

land surrounding three man-made lakes (North Carolina State Parks, 2019). Outside of the state 

park, the land use surrounding the facility is mostly commercial.

2.2.1 Geology

The Triassic Basin underlies Morrisville AASF #1, with bedrock of mostly Precambrian and 

Paleozoic age comprised of igneous, metamorphosed igneous, and sedimentary rocks (Heath, 

1980). The bedrock is exposed at the surface along steep hillsides, stream channels, and in 

roadcuts. Overlaying the bedrock is saprolite, or residuum, which ranges in thickness from 1 foot 

to more than 100 feet in the Piedmont (Heath, 1980). The facility is underlain by Triassic-aged, 

poorly sorted cobble to boulder conglomerate belonging to the Chatham Group and Newark 

Supergroup. The conglomerate is situated on the eastern boundary of the Triassic basin, marked 

by the Jonesboro Fault and located approximately 0.25 miles east of the facility (Hoffman and 

Gallagher, 1989; Blake and Clark, 2016). The fault is a stepped, high-angle normal fault with a 

northeast-southwest strike and westerly dip. The facility may also be within or close to the fault 

breccia zone (North Carolina Geological Survey, 1989). 

Soils in the area are considered a sandy loam, weathered from Triassic age sandstone, 

mudstone, and shale, with an increase in clay content with depth. Depth to bedrock at the facility

is estimated to be encountered at depths between 5 to 10 feet below ground surface (bgs)

(Weston, 2004). Sedimentary rocks in the property vicinity are comprised of fine- to mediumgrained sandstone, siltstone, and mudstone, with potential for encountering cobble to boulder 

conglomerate. The sandstone sequences are usually thick and are cross-bedded and interbedded 

with siltstone and muddy, fine-grained sandstone (DA, 2018a). 

During the SI, silt, clay, and silty sand were observed as the dominant lithology of the 

unconsolidated sediments below Morrisville AASF #1. The borings were completed at depths 

between 40 and 80 feet bgs. Below the unconsolidated sediments, various rock layers were 

observed including conglomerate, sandstone, siltstone, granite, and felsic schist. Rock was first 

encountered at various depths ranging from 5 feet bgs to 30 feet bgs. 
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Samples for grain size analyses were collected at two locations, AOI01-01 and AOI02-01, and 

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

indicate that the soil samples are comprised primarily of silt (29.98 percent [%] to 42.35%), clay 

(22.55% to 32.33%), and fine sand (21.63% to 24.29%). These results and facility observations 

are consistent with the reported depositional environment of the region. Boring logs are presented 

in Appendix E, and grain size results are presented in Appendix F.

2.2.2 Hydrogeology

Regional groundwater flows through fractures within metamorphic, igneous, and sedimentary 

bedrock. There is a complex two-component groundwater system where the regolith, composed 

of soil residuum, saprolite, alluvium, and colluvium, provides sheet like openings along the 

fractures for water storage (Heath, 1980). There is also a complex and variable thickness 

transition zone between the regolith and bedrock that consists of weathered and altered bedrock 

and numerous open near-horizontal fractures near the top of the bedrock (McSwain, 2013).

The saprolite that forms in the Piedmont consists of unconsolidated granular material that 

contains water in the pore spaces between rock particles. When it rains, water moves laterally 

and downward through the saprolite layer to points of groundwater seepage on the hillsides and 

to the streams in the adjacent valleys. The remaining water moves downward into the fractured 

bedrock (Heath, 1980). Groundwater resources in the Triassic Basin underlying the facility are 

poor. Wells sourcing groundwater in the Triassic Basin are low yielding and often cannot supply 

water for minimal household purposes (Welby, 1994). Previous studies in the area indicate 

shallow groundwater is supplied by low-producing shallow (approximately 30 to 50 feet bgs) joints 

and fractures (Weston, 2004), which may be further complicated by the presence of fault breccia 

zones, diabase dikes, and proximity to the Jonesboro Fault. Groundwater flow dynamics through 

the bedrock aquifer are based on the dip of the bedding planes, orientation of joint and fault 

systems, permeability, and the connection of fractures, faults, dikes, and joint systems present 

within the formations (S&ME, 2008). Based on US Geological Survey (USGS) well logs in the 

vicinity, depth to water of the perched groundwater (i.e., the water table aquifer) may be 

encountered as deep as 80 feet bgs at the facility (USGS, 2020). Groundwater flow is inferred to 

generally flow with surface topography to the south. However, groundwater flow may be strongly 

influenced by flow paths in the saprolite and may show local variability to the southwest or 

southeast. 

No drinking water wells exist at Morrisville AASF #1; the facility is provided drinking water from 

Jordan Lake by the Town of Cary, located southeast of the facility (Town of Cary, 2018). The North 

Carolina Department of Environmental Quality (NCDEQ) maintains a database of registered wells 

in the area. The database is only for public water supply wells and does not necessarily include 

private wells. Several public water supply wells exist within 4 miles of the facility to the east, 

northeast, and southeast (Figure 2-3). 

Depths to water measured in December 2021 during the SI ranged from 6.03 to 36.29 feet bgs.

Groundwater elevation contours from the SI are presented on Figure 2-4 and indicate that 

groundwater at the facility flows generally to the southwest.

2.2.3 Hydrology

Wake County is part of an uplifted peneplain dissected in places by a network of streams that 

generally flow in a southeasterly direction (Cawthorn, 1970). The Neuse River and its tributaries 

drain about 80% of the county. In the Triassic Basin, the valleys are U-shaped, and the flood 

plains are wide. The Basin is categorized as swampy depression or lake where the rock and 

mineral deposits were made during the Triassic period (Cawthorn, 1970). The soil at the facility is 

moderately well-drained, with a fair infiltration rate, and has moderate runoff. The runoff from the 
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facility drains southeast toward Haleys Branch, which flows into Lake Crabtree, Crabtree Creek, 

and eventually the Neuse River (DA, 2018a) (Figure 2-5). The facility’s surface drainage is 

diverted into two stormwater discharge outfalls (SDOs). Outfall SDO-001 drains runoff from the 

eastern portion of Morrisville AASF #1, including the aircraft apron, fuel farm, fueling station, 

firehouse, tactical equipment parking areas, and the armory. Outfall SDO-002 discharges the 

stormwater from the western portion of the facility that includes the area surrounding the hangar, 

the western boundary of the apron, gravel equipment parking areas, and the parking lot. There is 

minimal overland flow from the adjacent property, but runoff does not directly enter the Morrisville

AASF #1 outfalls (DA, 2018a). NCARNG has repaired the stormwater system along the southeast 

edge with a concrete conduit and grate. 

Two RDU outfalls are located near SDO-002. One of the RDU outfalls is directly adjacent to the 

SDO-002 pipe and housed in the same concrete structure. The other RDU outfall is located 

approximately 100 feet to the north of SDO-002 and drains the RDU stormwater retention pond

via a riser that controls the water level in the pond. Surface drainage from the RDU Maintenance 

Shop is diverted to this retention pond located to the south of the shop building. Flow from the 

RDU outfalls and both facility outfalls go in the direction of Haleys Branch on RDU property. 

Haleys Branch empties to Lake Crabtree, Crabtree Creek, and eventually the Neuse River. The 

facility also receives minimal overland flow from the RDU Airport property that does not directly 

release into the stormwater outfalls (NCDEQ, 2017). There is no connectivity between the facility 

stormwater system and the RDU pond. 

Drains in the wash rack, ground support equipment (GSE) building, hangar, and several other 

structures onsite are diverted to the Airport Authority's force main before transitioning to the 

sanitary sewer operated by the Town of Cary. The sanitary sewer drainage is diverted to the North 

Cary Water Reclamation Facility (NCWRF) located approximately 2 miles south of Morrisville 

AASF #1. The NCWRF discharges treated wastewater to Crabtree Creek, which flows into the 

Neuse River several miles downstream. The NCWRF is also a source of reclaimed water and 

biosolids. A portion of the treated effluent water is piped directly to homes and businesses in the 

area for reuse in irrigation, manufacturing processes, and industrial cooling. The system serves 

customers in designated service districts near the NCWRF (Town of Cary, 2019). The State of 

North Carolina permits Cary to divert up to 5.14 million gallons per day for direct reuse from their 

water reclamation facilities, but it is unclear what volume comes specifically from the NCWRF. 

Cary also operates a free bulk reclaimed water program at all three of its water reclamation 

facilities, including the NCWRF. Through this program, non-potable reclaimed water is available 

to approved customers in minimum volumes of 250 gallons per customer. The Town of Cary is 

permitted to provide a total of up to 600,000 gallons a day from its bulk systems; however, it is 

unclear what volume is produced from the NCWRF. Biosolids at the NCWRF are transported via 

truck to the South Cary Water Reclamation Facility, where they are dried and processed into Class 

A biosolids pellets using a thermal dryer (Town of Cary, 2019). The biosolids pellets are sold to 

the public and registered with the North Carolina Department of Agriculture and Consumer 

Services under the trade name Enviro Gems.

2.2.4 Climate

Morrisville AASF #1 is situated in central North Carolina, between mountains to the west and the 

Atlantic Ocean to the east. This particular location helps protect the facility from climate extremes 

(Cawthorn, 1970). Winters are mild and summers are hot and humid with plentiful rainfall 

throughout the year. Average temperatures range from 41.4 degrees Fahrenheit (°F) in January 

to 80.1°F in July. Average annual precipitation is 46.1 inches, with 5.11 inches falling in August 

and 2.72 falling in February. Raleigh averages 6.2 inches of snowfall per winter, with 3.3 inches 

accumulating in January (National Oceanic and Atmospheric Administration, 2020).
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AECOM 2-4

2.2.5 Current and Future Land Use

Morrisville AASF #1 is currently a controlled access facility and is adjacent to RDU. The facility 

supports rotary aircraft operations and is an Armory Readiness Center for the NCARNG. The 

facility is on North Carolina state property, which is controlled and operated by the DPS. 

Reasonably anticipated future land use is not expected to change from the current land use 

described here.

2.2.6 Sensitive Habitat and Threatened/ Endangered Species 

The following amphibians, birds, clams, fishes, plants, insects, and mammals are federally 

endangered, threatened, proposed, and/ or are listed as candidate species in Wake County, North 

Carolina (US Fish and Wildlife Service [USFWS], 2022). 

• Amphibians: Neuse River waterdog, Necturus lewisi, (threatened)

• Birds: Red-cockaded woodpecker, Picoides borealis (endangered)

• Clams: Tar River spinymussel, Elliptio steinstansana (endangered); Dwarf wedgemussel,

Alasmidonta heterodon (endangered); Yellow lance, Elliptio lanceolata (threatened); Atlantic

pigtoe, Fusconaia masoni (threatened); Green floater, Lasmigona subviridis (under review)

• Fishes: Carolina madtom, Noturus furiosus (endangered); Cape Fear shiner, Notropis

mekistocholas (endangered)

• Flowering plants: Michaux's sumac, Rhus michauxii (endangered)

• Insects: Monarch butterfly, Danaus plexippus (candidate)

• Mammals: Little brown bat, Myotis lucifugus (under review); Tricolored bat, Perimyotis

subflavus (under review)

2.3 History of PFAS Use

During the PA, eight potential release areas were identified: the Wash Rack Fire Training Area 

(FTA), Delta Row FTA, Hangar Leak Area, GSE Building Leak Area, GSE Building Temporary TriMax Storage, Firehouse Aqueous Film Forming Foam (AFFF) Storage Area, Firetruck Flush Area, 

and Long-Term Tri-Max Storage Area (AECOM, 2020). PFAS-containing AFFF may have been 

released during fire training activities at then Wash Rack and Delta Row FTAs; leaks from the 

AFFF dispensing system in the Hangar; AFFF storage in the GSE Building and LongTerm/Temporary Tri-Max Storage Areas; and AFFF releases during firetruck flushing and leaks at 

the Firehouse The potential release areas were grouped into five AOIs, based on proximity to one 

another and presumed groundwater flow. A description of AOI 1 through AOI 5 is presented in 

Section 3. 
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Site Inspection Report

Morrisville Army Aviation Support Facility #1, North Carolina

AECOM 3-1

3. Summary of Areas of Interest

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

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

identified at MorrisvilleAASF #1 and grouped into fiveAOIs (AECOM, 2020). The potential release 

areas are shown on Figure 3-1. 

3.1 AOI 1 Wash Rack and GSE Building

AOI 1 encompasses the Wash Rack Area, Temporary Tri-Max 30TM Storage Area, and GSE 

Building. The Wash Rack Area was an active FTA, with AFFF used from the 1990s until 2010. 

AFFF-related training was conducted approximately once every 2 years. The wash rack was also 

used as the designated area for filling and maintaining the Tri-Max 30TM carts. A single grated inlet 

in the center of the Wash Rack captures surface drainage which flows through the oil-water 

separator. The oil-water separator is then diverted to the Airport Authority's force main before 

transitioning to the sanitary sewer operated by the Town of Cary. During the AFFF-related 

activities within AOI 1, it is possible that AFFF was inadvertently released outside of the wash rack 

structure, where it would have drained into a stormwater inlet and discharged to Haleys Branch 

or infiltrated the surface soil near the Wash Rack Area.

The GSE Building, located to the west of the wash rack, contains a utility room housing a manual 

AFFF dispensing system, which has never been activated by either testing or servicing of the 

system. However, leaks and seepage have been observed from two of the system’s pumps. The 

leaks were confined to the GSE Building utility room. It is unknown when or the duration in which 

these leaks and spills occurred. NCARNG employs absorbing socks and booms to protect the 

building's drainage system. In a separate room in the GSE Building, approximately 20 5-gallon 

buckets of Ansulite 3% AFFF were observed to be stored at the time of the PA. NCARNG has 

since indicated that all 5-gallon buckets of AFFF have since been removed from the facility for 

proper disposal. The storage room and utility room both contain floor drains that flow to an oilwater separator before flowing to the sanitary sewer system of the Town of Cary. Migration from 

the floor of the GSE building to the grass outside the door is possible. Surface runoff at AOI 1 

drains via sheet flow toward the southwest.

3.2 AOI 2 Delta Row FTA

AOI 2 encompasses the long grassy area along Delta Row and was the targeted area for AFFF 

training with Tri-Max 30TM carts. The Delta Row FTA was active from the 1988 to 2010, with regular 

training occurring approximately once every 2 years. The RDU fire department trains along Delta 

Row with NCARNG on a regular basis to ensure they are properly trained to respond to helicopter 

emergencies to support NCARNG; during the training sessions, foam was never used. RDU 

spends a majority of the training sessions becoming familiar with the aircraft and completing 

building walk-throughs. The grassy area of the Delta Row FTA is also part of the facility’s 

stormwater drainage system, with a series of inlet grates running parallel to the edge of the apron. 

Surface water runoff at AOI 2 is captured by storm drains that channel flow southwest to several 

other stormwater conveyance pipes and is ultimately discharged to Haleys Branch through outfall 

SDO-001, which flows into Lake Crabtree and Crabtree Creek about 2 miles south before entering 

the Neuse River several miles downstream. As a result of AFFF releases at the Delta Row FTA, 

it is possible releases have been transported to Haleys Branch, Lake Crabtree, Crabtree Creek,

and the Neuse River. 
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Morrisville Army Aviation Support Facility #1, North Carolina

AECOM 3-2

3.3 AOI 3 Firehouse AFFF Storage and Flush Area

AOI 3 encompasses the area inside the vehicle bay of the Firehouse, where AFFF is currently 

stored, and the adjacent area to the south, where one firetruck was flushed after an internal AFFF 

leak was discovered. At the time of the visual SI, 42 5-gallon buckets of 3% AFFF were stored 

along the eastern wall of the vehicle bay. These 5-gallon buckets have since been removed from 

the facility for proper disposal along with those from the GSE Building. The firetruck developed 

an internal backflow leak between the AFFF tank and the water tank. The AFFF leak was 

contained to the firetruck’s water tank, but prior to its repair, the water tank was completely 

emptied onto the parking area located immediately outside the Firehouse vehicle bay. 

Floor drains inside the Firehouse are routed to the oil/water separator before discharging to the 

sanitary sewer system of the Town of Cary. The water emptied from the leaking firetruck would 

have been conveyed to drains outside the vehicle bay that are part of the same stormwater 

drainage system associated with AOI 2. It is possible that the flushed water, which contained dilute 

concentrations of AFFF, also migrated to the surrounding surface soil to the south, beyond the 

impervious surfaces of the parking area.

3.4 AOI 4 Hangar

AOI 4 encompasses the Morrisville AASF #1 Hangar, which contains an actively charged AFFF 

dispensing system. Located on the floor in the center of each wall of the Hangar, Ansul AFFF 

pumps are connected to hand-reels and are currently charged with 35 gallons of 3% AFFF. The 

Ansul pump in the center of the southwestern wall developed a leak overnight in 2018. The volume 

of the leak was approximately 5 gallons and was confined to the area immediately surrounding 

the pump. Floor drains in the Hangar are routed to the oil/water separator before discharging to 

the sanitary sewer operated by the Town of Cary. It is possible, however, that AFFF also leached 

through the concrete floor and into the subsurface soil and groundwater.

3.5 AOI 5 Long-Term Tri-Max 30TM Storage Area

AOI 5 encompasses the Long-Term Tri-Max 30TM Storage Area on the gravel-covered ground

north of the Morrisville AASF #1 Hangar, where Tri-Max 30TM carts are permanently stored. At the 

time of the PA, 12 empty Tri-Max 30TM carts were located in this storage area. The Tri-Max 30TM

carts have been stored in their current location since 2009 with no known AFFF leaks or releases. 

NCARNG personnel have indicated that AFFF-containing Tri-Max 30TM carts remain at the facility; 

however, are scheduled to have their contents consolidated and removed for proper disposal in 

August 2023. 

Surface water in the Long-Term Tri-Max 30TM Storage Area drains to the south, and a stormwater 

inlet grate is located immediately south of the Tri-Max 30TM carts. This stormwater grate is 

connected to the stormwater outfall near the western boundary of the facility, which drains to an 

unnamed tributary of Haleys Branch.
Firetruck Flush Area

GSE Building Leak Area

Wash Rack FTA

Temporary 

Tri-Max Storage

Hangar Leak Area

Delta Row FTA

Long Term Tri-Max Storage

Firehouse AFFF Storage Area

RDU Stormwater

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Haleys Branch

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Site Inspection Report

Morrisville Army Aviation Support Facility #1, North Carolina

AECOM 4-1

4. Project Data Quality Objectives

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

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

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

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

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

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

AOIs.

4.1 Problem Statement

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

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

SLs are presented in Section 6.1 of this report. 

4.2 Information Inputs

Primary information inputs included:

• The PA for Morrisville AASF #1 (AECOM, 2020);

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

with the site-specific Uniform Federal Policy (UFP)-QAPP Addendum (AECOM, 2021a); and

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

parameters measured at the time of sampling.

4.3 Study Boundaries

The scope of the SI was bounded by the property limits of the facility (Figure 2-2). 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 late fall and early winter seasons, which was the 

earliest available time field resources were available to complete the study. 

4.4 Analytical Approach

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

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

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

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

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

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 decisionmaking (DoD, 2019a; DoD, 2019b; USEPA, 2017). 
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Morrisville Army Aviation Support Facility #1, North Carolina

AECOM 4-2

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

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

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

requirements of the SI QAPP Addendum (AECOM, 2021a). 
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Morrisville Army Aviation Support Facility #1, North Carolina

AECOM 5-1

5. Site Inspection Activities

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

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

in accordance with the following approved documents: 

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

(PQAPP) dated March 2018 (AECOM, 2018a);

• Final Programmatic Accident Prevention Plan dated July 2018 (AECOM, 2018b);

• Final Preliminary Assessment Report, Morrisville Army Aviation Support Facility #1, North

Carolina dated August 2020 (AECOM, 2020);

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

Morrisville Army Aviation Support Facility #1, North Carolina dated September 2021

(AECOM, 2021a); and

• Final Site Safety and Health Plan, Morrisville Army Aviation Support Facility #1, North

Carolina dated November 2021 (AECOM, 2021b).

The SI field activities were conducted from 2 to 30 December 2021 and consisted of utility clearance, 

sonic soil boring drilling, soil sample collection, permanent monitoring well installation, groundwater 

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

QAPP Addendum (AECOM, 2021a). 

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

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

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

• Twenty (20) soil samples from 14 boring locations;

• Six groundwater samples from six newly installed permanent monitoring wells;

• Two groundwater samples from two existing permanent monitoring wells; and

• Twenty (20) quality assurance (QA)/quality control (QC) samples.

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

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

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

in Appendix B1. Sampling forms are provided in Appendix B2, Well Development Forms are

provided in Appendix B3, and land survey data are provided in Appendix B4. Additionally, a 

photographic log of field activities is provided in Appendix C. 

5.1 Pre-Investigation Activities

In preparation for the SI field activities, project team members participated in Technical Project 

Planning (TPP) meetings, performed utility clearance, and sampled decontamination source 

water. Details for each of these activities are presented below.

5.1.1 Technical Project Planning

The US Army Corps of Engineers (USACE) TPP Process, Engineer Manual (EM) 200-1-2 

(USACE, 2016) defines four phases to project planning: 1.) defining the project phase; 2.) 

determining data needs; 3.) developing data collection strategies; and 4.) finalizing the data 
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Morrisville Army Aviation Support Facility #1, North Carolina

AECOM 5-2

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 3 June 2021, prior to SI field activities. The 

combined TPP Meeting 1 and 2 was conducted in general accordance with EM 200-1-2. The 

stakeholders for this SI include the ARNG, NCARNG, USACE, NCDEQ, and RDU. Stakeholders 

were provided the opportunity to make comments on the technical sampling approach and 

methods at the combined TPP Meeting 1 and 2. The outcome of the combined TPP Meeting 1 

and 2 was memorialized in the SI QAPP Addendum (AECOM, 2021a).

A TPP Meeting 3 will be scheduled to discuss the results of the SI. Meeting minutes for TPP 3 will 

be included in Appendix D of this report. Future TPP meetings will provide an opportunity to 

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

5.1.2 Utility Clearance

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

Carolina 811 utility clearance provider to notify them of intrusive work on 23 November 2021. 

Additionally, AECOM contracted Ground Penetrating Radar Systems (GPRS), a private utility 

location service, to perform utility clearance. GPRS performed utility clearance of the proposed 

boring locations on 2 December 2021 with input from the AECOM field team and Morrisville AASF

#1 facility staff. General locating services and ground-penetrating radar were used to complete 

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

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

5.1.3 Source Water and Sampling Equipment Acceptability

A potable water source at Morrisville AASF #1 was sampled on 14 April 2021 to assess usability 

for decontamination of drilling equipment. Because it had been over 6 months since the first 

potable water source sample (MA-DECON) was collected, another sample was collected on 22 

December 2021 (MA-PW-02). Results of both samples collected confirmed this source to be 

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

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

results of the decontamination water sample associated with the source used during the SI are 

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

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

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

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

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

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

member regarding the allowable materials within the sampling environment.

5.2 Soil Borings and Soil Sampling

Borings were installed in grass or unpaved areas where possible, to avoid disturbing concrete or 

asphalt surfaces. Soil samples were collected via Sonic drilling methods, in accordance with the 

SI QAPP Addendum (AECOM, 2021a). A Terra Sonic TSI 150CC sampling system was used to 

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

top 5 feet of the boring, in accordance with AECOM utility clearance procedures. The soil boring 

locations are shown on Figure 5-1, and depths are provided Table 5-2.
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Morrisville Army Aviation Support Facility #1, North Carolina

AECOM 5-3

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

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

approximately 1 foot above the groundwater table, and one subsurface soil sample at the midpoint between the surface and the groundwater table, if the depth to water was up to 30 feet bgs 

or shallower, or from 13 to 15 feet bgs. However, only two soil samples were collected from 

locations AOI01-01, MA-01, MA-02, MA-03 and MA-04 due to the presence of conglomerate rock 

in the interval above the water table. Additionally, only one soil sample (0 to 2 feet bgs) was 

collected from location AOI01-02 as the area was inaccessible by the drill rig due to space 

constraints. Multiple attempts were made to collect subsurface soil samples at AOI01-02 via hand 

auger; however, gravel was repeatedly encountered at approximately 2 feet bgs.

The soil cores were continuously logged for lithological descriptions by an AECOM field geologist 

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

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

Observations and measurements were recorded on sampling forms (Appendix B2) and in a nontreated field logbook (i.e., composition notebook). Depth interval, recovery thickness, PID 

concentrations, moisture, relative density, color (using a Munsell soil color chart), and texture 

(using the USCS) were recorded. The boring logs are provided in Appendix E. 

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

as the dominant lithology of the unconsolidated sediments below Morrisville AASF #1. The 

borings were completed at depths between 40 and 80 feet bgs. Below the unconsolidated 

sediments various rock layers were observed including conglomerate, sandstone, siltstone, 

granite, and felsic schist. Rock was first encountered at various depths ranging from 5 feet bgs to 

30 feet bgs. These observations are consistent with the understood depositional environment of 

the region.

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

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

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

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

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

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

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

as the accompanying samples. Matrix spike (MS)/MS 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, 

equipment rinsate blanks were collected at a rate of 5% and analyzed for the same parameters 

as the soil samples. A temperature blank was placed in each cooler to ensure that samples were 

preserved at or below 6 degrees Celsius during shipment.

Soil borings were converted to permanent monitoring wells. This conversion is described in 

Section 5.3 below. 

5.3 Permanent Well Installation and Groundwater Sampling

During the SI, six permanent monitoring wells were installed within or downgradient of potential 

source areas. The locations of the wells are shown on Figure 5-1. 

A Terra Sonic Crawler TSi 150CC drill rig was used to install six 2-inch diameter monitoring wells. 

The monitoring wells were constructed with Schedule 40 polyvinyl chloride, flush threaded 10-

foot sections of riser, 10-foot section of 0.010-inch slotted well screen, and a threaded bottom 

cap. A filter pack of 20/40 silica sand was installed in the annulus around the well screen to a 

minimum of 4-feet above the well screen. A 5-foot-thick bentonite seal was placed above the filter 
Site Inspection Report

Morrisville Army Aviation Support Facility #1, North Carolina

AECOM 5-4

sand and hydrated with distilled water. Bentonite grout was placed in the well annulus from the 

top of the bentonite seal to ground surface. The bentonite grout was allowed to set for 24 hours 

prior to well completion in accordance with the SI QAPP Addendum (AECOM, 2021a). All 

monitoring wells were completed with flush mount well vaults. The screen interval of each of the 

groundwater monitoring wells is provided in Table 5-2.

Well screens were constructed to bracket the surficial water table based on lithology and field 

conditions as interpreted by the on-site field geologists. Rotary sonic drilling methods require the

introduction of drilling fluids (potable water) to the borehole for lubrication and cooling during 

coring. Adding water to the borehole makes it difficult to determine the precise elevation at which 

groundwater is first encountered. Techniques such as packer testing, where the borehole was 

sealed and subsequently purged dry to monitor for potential groundwater recharge, were 

implemented to assist in determining natural groundwater elevation during well installation. 

Additionally, there is potential that formational groundwater at some of the monitoring well 

locations could be under pressure and is pushing up into the well and reflecting a submerged 

screen.

Development and sampling of wells was completed in accordance with the SI QAPP Addendum 

(AECOM, 2021a). The newly installed monitoring wells were developed no sooner than 24 hours 

following installation by pumping and surging using a variable speed submersible pump. Samples 

were collected no sooner than 24 hours following development via low-flow sampling methods 

using a QED Sample Pro® bladder pump with disposable, PFAS-free, HDPE tubing. New tubing 

was used at each well, and the pumps were decontaminated between each well. The wells were 

purged at a rate determined in the field to reduce draw down prior to sampling. Water quality 

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

potential, and turbidity) were measured using a water quality meter and recorded on the field 

sampling form (Appendix B2). Water levels were measured to the nearest 0.01 inch and 

recorded. Additionally, a subsample of each groundwater sample was collected in a separate 

container, and a shaker test was completed to identify if there were any foaming. No foaming was 

noted in any of the groundwater samples.

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

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

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

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

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

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

same parameters as the accompanying samples. One field reagent blank was collected in 

accordance with the PQAPP (AECOM, 2018a). A temperature blank was placed in each cooler to 

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

5.4 Synoptic Water Level Measurements

A synoptic groundwater gauging event was performed on 30 December 2021. Groundwater 

elevation measurements were collected from the six new temporary monitoring wells and two 

existing monitoring wells. Water level measurements were taken from the northern side of the 

well casing. A groundwater flow contour map is provided in Figure 2-4. Groundwater elevation 

data are provided in Table 5-2.

5.5 Surveying

The northern side of each well casing was surveyed by North Carolina-licensed land surveyors 

following guidelines provided in the SOPs provided in the SI QAPP Addendum (AECOM, 2021a). 
Site Inspection Report

Morrisville Army Aviation Support Facility #1, North Carolina

AECOM 5-5

Survey data from the newly installed wells on the facility were collected on 30 December 2021 in 

the applicable Universal Transverse Mercator zone projection with North American Datum of 1983 

(horizontal) and North American Vertical Datum 1988 (vertical). The surveyed well data are

provided in Appendix B4. 

5.6 Investigation-Derived Waste

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

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

accordance with the SI QAPP Addendum (AECOM, 2021a) and with the DA Guidance for 

Addressing Releases of PFAS, Q18 (DA, 2018b). 

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

drums and left onsite in a designated waste storage area. The soil IDW was not sampled and 

assumes the characteristics of the associated soil samples collected from that source location. 

Based on laboratory results, containerized soil cuttings will be managed and disposed by ARNG, 

under a separate contract held by EA Engineering, Science, and Technology, Inc. (EA). EA will 

distribute the soil on the downgradient side of the associated borehole.

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

decontamination fluids) were contained in labeled, 55-gallon drums, and left onsite in a 

designated waste storage area. The liquid IDW was not sampled and assumes the characteristics 

of the associated groundwater samples collected from that source location. Based on laboratory 

results, containerized liquid IDW will be managed and disposed by ARNG under a separate contract 

for Treating Liquid Investigation-Derived Material (Purge water, drilling water, and decontamination 

fluids) (EA, 2021).

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

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

activities were disposed of at a licensed solid waste landfill.

5.7 Laboratory Analytical Methods

Samples were analyzed by LC/MS/MS compliant with QSM 5.3 Table B-15 at Pace Analytical Gulf 

Coast in Baton Rouge, Louisiana, a DoD ELAP and NELAP certified laboratory. Soil samples 

were also analyzed for TOC using USEPA Method 9060A and pH by USEPA Method 9045D. 

5.8 Deviations from SI QAPP Addendum

No deviations from the SI QAPP Addendum were identified during review of the field 

documentation. 
Site Inspection Report

Morrisville Army Aviation Support Facility #1, North Carolina

AECOM 5-6

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Table 5-1

Site Inspection Samples by Medium

Site Inspection Report, Salisbury AASF #2, North Carolina

Sample Identification

Sample

Collection 

Date/Time

Sample Depth 

(feet bgs)

LC/MS/MS compliant with QSM 5.3 Table B-15TOC(USEPA Method 9060A)pH (USEPA Method 9045D)Grain Size (ASTM D-422)

Comments

AOI01-01-SB-00-02 12/14/2021 10:30 0-2 x

AOI01-01-SB-13-15 12/16/2021 13:00 13-15 x x

AOI01-02-SB-00-02 12/7/2021 8:20 0-2 x x x

AOI01-02-SB-00-02D 12/7/2021 8:20 0-2 x x FD

AOI01-02-SB-00-02-MS 12/7/2021 8:20 0-2 x x MS

AOI01-02-SB-00-02-MSD 12/7/2021 8:20 0-2 x x MSD

AOI01-03-SB-00-02 12/6/2021 15:00 0-2 x

AOI01-04-SB-00-02 12/6/2021 16:40 0-2 x

AOI01-05-SB-00-02 12/10/2021 11:50 0-2 x

AOI02-01-SB-00-02 12/16/2021 9:30 0-2 x x x

AOI02-01-SB-00-02-D 12/16/2021 9:30 0-2 x FD

AOI02-01-SB-08-10 12/16/2021 11:30 8-10 x

AOI02-01-SB-13-15 12/16/2021 11:40 13-15 x

AOI02-02-SB-00-02 12/7/2021 15:00 0-2 x

AOI03-01-SB-00-02 12/6/2021 13:30 0-2 x x x

AOI04-01-SB-00-02 12/6/2021 14:15 0-2 x x x

AOI05-01-SB-00-02 12/7/2021 13:35 0-2 x x x

MA-01-SB-00-02 12/6/2021 12:30 0-2 x

MA-01-SB-00-02MS 12/6/2021 12:30 0-2 x MS

MA-01-SB-00-02MSD 12/6/2021 12:30 0-2 x MSD

MA-01-SB-11-13 12/6/2021 13:30 11-13 x

MA-02-SB-00-02 12/9/2021 12:30 0-2 x

MA-02-SB-00-02MS 12/9/2021 12:30 0-2 x MS

MA-02-SB-00-02MSD 12/9/2021 12:30 0-2 x MSD

MA-02-SB-03-05 12/9/2021 12:45 3-5 x

MA-03-SB-00-02 12/7/2021 16:00 0-2 x

MA-03-SB-00-02-D 12/7/2021 16:00 0-2 x FD

MA-03-SB-13-15 12/7/2021 16:55 13-15 x x x

MA-04-SB-00-02 12/9/2021 15:45 0-2 x

MA-04-SB-02-04 12/9/2021 16:15 2-4 x

AOI01-01-GW 12/30/2021 14:35 NA x

AOI02-01-GW 12/30/2021 12:55 NA x

AOI02-01-GW-D 12/30/2021 12:55 NA x FD

AOI03-MW-DEEP-GW 12/7/2021 12:40 NA x

AOI03-MW-SHALLOW-GW 12/7/2021 10:25 NA x

MA-01-GW 12/14/2021 14:15 NA x

MA-01-GW-MS 12/14/2021 14:15 NA x MS

MA-01-GW-MSD 12/14/2021 14:15 NA x MSD

MA-02-GW 12/30/2021 15:45 NA x

MA-03-GW 12/13/2021 14:50 NA x

MA-04-GW 12/30/2021 10:35 NA x

MA-DECON 4/14/2021 11:10 NA x Decon water source

MA-FRB-04142021 4/14/2021 11:15 NA x

MA-FRB-01 12/8/2021 13:30 NA x

MA-ERB-01 12/7/2021 14:20 NA x Hand Auger

MA-ERB-02 12/9/2021 12:00 NA x

MA-ERB-03 12/7/2021 11:00 NA x Bladder Pump

MA-ERB-04 12/30/2021 16:10 NA x Bladder Pump

MA-PW-02 12/22/2021 8:30 NA x

Soil Samples

Quality Control Samples

Groundwater Samples

AECOM 5-7
Table 5-1

Site Inspection Samples by Medium

Site Inspection Report, Salisbury AASF #2, North Carolina

Sample Identification

Sample

Collection 

Date/Time

Sample Depth 

(feet bgs)

LC/MS/MS compliant with QSM 5.3 Table B-15TOC(USEPA Method 9060A)pH (USEPA Method 9045D)Grain Size (ASTM D-422)

Comments

Notes:

AASF = Army Aviation Support Facility MA = Morrisville AASF

AOI = Area of Interest MS/MSD = matrix spike/ matrix spike duplicate

ASTM = American Society for Testing and Materials MW = monitoring well

bgs = below ground surface NA = not applicable

D = duplicate pH = potential for hydrogen

DECON = decon water source PW = potable water

ERB = equipment rinsate blank QSM = Quality Systems Manual

FD = field duplicate SB = soil boring

FRB = field reagent blank TOC = total organic carbon

GW = groundwater USEPA = United States Environmental Protection Agency

LC/MS/MS = Liquid Chromatography Mass Spectrometry

AECOM 5-8
Table 5-2

Soil Boring Depths, Permanent Monitoring Well Screen Intervals, and Groundwater Elevations

Site Inspection Report, Salisbury AASF #2, North Carolina

Area of 

Interest

Boring 

Location

Soil Boring 

Depth 

(feet bgs)

Permanent Well 

Screen Interval 

(feet bgs)

Top of Casing 

Elevation 

(feet NAVD88)

Ground Surface 

Elevation 

(feet NAVD88)

Depth to 

Water

(feet btoc)

De

W

(fee

MA-01 60 49 - 59 402.03 402.30 5.76 6MA-02 40 29 - 39 389.59 389.97 33.51 3

MA-03 50 39 - 49 398.12 398.36 23.47 2

MA-04 80 69 - 79 392.77 393.05 34.25 3

1 AOI01-01 60 49 - 59 399.73 400.11 13.12 1

2 AOI02-01 40 29 - 39 399.92 400.09 10.21 1

3 AOI03-MW-Shallow NA 4.5 - 9.5 395.00 395.28 6.45 63 AOI03-MW-Deep NA 41.3 - 51.3 395.15 395.42 36.02 3

Notes:Permanent well screen set above total depth to capture groundwater interface

AASF = Army Aviation Support FacilityAOI = Area of Interestbgs = below ground surfacebtoc = below top of casingMA = Morrisville AASFMW = monitoring wellNAVD88 = North American Vertical Datum 1988

Boundary

AECOM 
AECOM 5-10

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M 5-10
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?!

?!

?!

?!

"S

"S

"S "S

"S

"S

"S

"S

RDU Washrack

RDU Stormwater

Retention Pond

RDU Maintenance Shop

Haleys Branch

SDO-001

SDO-002

Airport Authority

Property

AOI01-01

AOI02-01

AOI03-MW-DEEP

AOI03-MW-SHALLOW

MA-01

MA-02

MA-03

MA-04

AOI01-04

AOI01-05

AOI01-03

AOI01-02

AOI03-01

AOI02-02

AOI04-01

AOI05-01

0 120 240 480

Feet

Figure 5-1

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Morrisville AASF #1, NC

9/13/2022

9/13/2022

9/13/2022

MS

MB

CM

GIS BY

CHK BY

PM

9/13/2022

Site Inspection Sample Locations

12420 Milestone Center Drive

Germantown, MD 20876

A! Existing Monitoring Well

?! Monitoring Well

"S Surface Soil Sample

Facility Boundary

Water Body

River/Stream

Utilities

Surface Water Flow Direction

Groundwater Flow Direction

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

1:2,880 ­ PROJECT

AECOM 5-11
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5-12
Site Inspection Report

Morrisville Army Aviation Support Facility #1, North Carolina

AECOM 6-1

6. Site Inspection Results

This section presents the analytical results of the SI. The SLs used in this evaluation are 

presented in Section 6.1. A discussion of the results for each AOI is provided in Section 6.3

through Section 6.7. Tables 6-2 through Table 6-4 present results in soil or groundwater for the 

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

laboratory reports are provided in Appendix G. 

6.1 Screening Levels

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

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

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

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

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

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

6-1 below.

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

Analyteb

Residential

(Soil)

(μg/kg)a 

0-2 feet bgs

Industrial/ 

Commercial 

Composite 

Worker

(Soil)

(μg/kg)a 

2-15 feet bgs

Tap Water

(Groundwater)

(ng/L)a

PFOA 19 250 6 

PFOS 13 160 4 

PFBS 1,900 25,000 601 

PFHxS 130 1,600 39

PFNA 19 250 6 

Notes:

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

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

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

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

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

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

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

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

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

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

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

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

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

because 15 feet is the anticipated limit of construction activities. 
Site Inspection Report

Morrisville Army Aviation Support Facility #1, North Carolina

AECOM 6-2

6.2 Soil Physicochemical Analyses

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

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

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

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

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

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

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

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

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

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

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

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

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

6.3 AOI 1 

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

AOI 1: Wash Rack Area and GSE Building. The soil and groundwater results are summarized on 

Table 6-2 through Table 6-4. Soil and groundwater results are presented on Figure 6-1 through 

Figure 6-7. 

6.3.1 AOI 1 Soil Analytical Results 

Table 6-2 and Table 6-3 summarize the soil results. Figure 6-1 through Figure 6-5 present the 

ranges of detections in soil. 

Soil was sampled from surface soil (0 to 2 feet bgs) from boring locations AOI01-01 through 

AOI01-05. Soil was also sampled from shallow subsurface soil (13 to 15 feet bgs) from boring 

location AOI01-01. PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in surface soil at 

concentrations below their respective SLs. The maximum concentrations detected were PFOA at 

3.90 micrograms per kilogram (μg/kg); PFOS at 6.67 μg/kg; PFHxS at 3.34 μg/kg; PFNA at 3.56 

μg/kg; and PFBS at 0.097 J μg/kg. 

PFHxS and PFBS were detected in shallow subsurface soil at concentrations below their 

respective SLs. PFHxS was detected at location AOI01-01, with a concentration of 0.101 J μg/kg. 

PFBS was detected at location AOI01-01, with a concentration of 0.039 J μg/kg. PFOA, PFOS, 

and PFNA were not detected in shallow subsurface soil. 

Soil was also sampled from surface soil (0 to 2 feet bgs) at the facility boundary locations MA-02 

and MA-04, which are downgradient of AOI 1. Soil was also sampled from shallow subsurface 

soil with intervals of 2 to 4 feet bgs (MA-04) and 3 to 5 feet bgs (MA-02). PFOA, PFOS, and 

PFHxS were detected in surface soil at concentrations below their respective SLs. The maximum 

concentrations detected were PFOA at 0.156 J μg/kg; PFOS at 0.246 J μg/kg; and PFHxS at 

0.114 J μg/kg. PFNA and PFBS were not detected in surface soil at either location. PFOS was 

detected in shallow subsurface soil below the SL with a maximum concentration of 0.074 J μg/kg. 

PFOA, PFHxS, PFNA, and PFBS were not detected in shallow subsurface soil at either location. 

6.3.2 AOI 1 Groundwater Analytical Results 

Table 6-4 summarizes the groundwater results. Figure 6-6 and Figure 6-7 present the ranges of 

detections in groundwater. 
Site Inspection Report

Morrisville Army Aviation Support Facility #1, North Carolina

AECOM 6-3

Groundwater was sampled from permanent monitoring well AOI01-01. PFHxS was detected 

above the SL of 39 nanograms per liter (ng/L), with a concentration of 73.3 ng/L. PFOA and PFBS 

were detected in groundwater at concentrations below their respective SLs at a concentration of 

4.76 ng/L and 32.9 ng/L, respectively. PFOS and PFNA were not detected in groundwater at 

AOI01-01. 

Groundwater was also sampled from permanent monitoring wells MA-02 and MA-04, which are 

downgradient of AOI 1. PFOS and PFNA were not detected in groundwater at either location. 

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

The maximum concentrations detected are as follows: 

• PFOA was detected below the SL at location MA-02, with a concentration of 0.816 J

ng/L. PFOS, PFHxS, PFNA, and PFBS were not detected in groundwater.

• PFOA was detected above the SL of 6 ng/L at location MA-04, with a concentration of

6.91 ng/L. PFHxS was detected above the SL of 39 ng/L, with a concentration of 42.0

ng/L. PFBS was detected below the SL, with a concentration of 5.05 ng/L. PFOS and

PFNA were not detected in groundwater.

6.3.3 AOI 1 Conclusions

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

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

above their respective SLs at AOI01-01 and MA-04, downgradient of AOI 1. Based on the 

exceedances of the SLs in groundwater, further evaluation at AOI 1 is warranted. 

6.4 AOI 2 

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

AOI 2: Delta Row FTA. The results in soil and groundwater are summarized on Table 6-2 through 

Table 6-4. Soil and groundwater results are presented on Figure 6-1 through Figure 6-7. 

6.4.1 AOI 2 Soil Analytical Results

Table 6-2 and Table 6-3 summarize the soil results. Figure 6-1 through Figure 6-5 present the 

ranges of detections in soil. 

Soil was sampled from surface soil (0 to 2 feet bgs) from boring locations AOI02-01 and AOI02-

02. Soil was also sampled from shallow subsurface soil (13 to 15 feet bgs) from boring location

AOI02-01. PFOA and PFNA were detected in surface soil at concentrations above their respective

SLs. The maximum concentrations detected are as follows:

• PFOA was detected below the SL at location AOI02-01, with a concentration of 0.435 J

μg/kg. PFNA was detected below the SL at location AOI02-01, with a concentration of

0.882 J μg/kg.

• PFOA was detected above the SL of 19 μg/kg at AOI02-02, with a concentration of 32.5

μg/kg. PFNA was detected above the SL of 19 μg/kg, with a concentration of 57.3 μg/kg.

PFOS, PFHxS, and PFBS were detected in surface soil at concentrations below their respective 

SLs at both locations AOI02-01 and AOI02-02. All concentrations were below 6 μg/kg. PFOA, 

PFOS, PFHxS, PFNA, and PFBS were not detected in shallow subsurface soil.

Soil was also sampled from surface soil (0 to 2 feet bgs) and shallow subsurface soil (3 to 5 feet 

bgs) at the facility boundary location MA-02, which is downgradient of AOI 2. PFOA, PFOS, and 

PFHxS were detected in surface soil, at concentrations below their respective SLs. All 
Site Inspection Report

Morrisville Army Aviation Support Facility #1, North Carolina

AECOM 6-4

concentrations were below 1 J μg/kg. PFNA and PFBS were not detected in surface soil at location 

MA-02. PFOA, PFOS, PFHxS, PFNA, and PFBS were not detected in shallow subsurface soil at 

location MA-02. 

6.4.2 AOI 2 Groundwater Analytical Results

Table 6-4 summarizes the groundwater results. Figure 6-6 and Figure 6-7 present the ranges of 

detections in groundwater. 

Groundwater was sampled from permanent monitoring well AOI02-01. PFOA was detected above 

the SL of 6 ng/L, with a maximum concentration of 7.96 ng/L in the field duplicate sample (AOI02-

01-GW-D). PFHxS and PFBS were detected in groundwater at concentrations below their 

respective SLs, with maximum concentrations in the field duplicate sample of 37.2 ng/L and 7.49 

ng/L, respectively. PFOS and PFNA were not detected in groundwater at AOI02-01.

Groundwater was also sampled from the permanent monitoring well MA-02, which is 

downgradient of AOI 2. PFOA was detected below the SL of 6 ng/L, with a concentration of 0.816 

J ng/L. PFOS, PFHxS, PFNA, and PFBS were not detected in groundwater at location MA-02. 

6.4.3 AOI 2 Conclusions

Based on the results of the SI, PFOA and PFNA were detected in soil at concentrations above 

their respective SLs. PFOA was detected in groundwater at concentrations above its respective 

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

warranted. 

6.5 AOI 3

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

AOI 3: Firehouse AFFF Storage and Firetruck Flush Areas. The results in soil and groundwater

are presented in Table 6-2 through Table 6-4. Soil and groundwater results are presented on 

Figure 6-1 through Figure 6-7.

6.5.1 AOI 3 Soil Analytical Results

Table 6-2 and Table 6-3 summarize the soil results. Figure 6-1 through Figure 6-5 present the 

ranges of detections in soil. 

Soil was sampled from surface soil (0 to 2 feet bgs) from boring location AOI03-01. PFOA, PFOS, 

PFHxS, PFNA, and PFBS were detected at concentrations below their respective SLs in surface 

soil. The maximum concentrations detected were PFOA at 0.232 J μg/kg; PFOS at 1.59 μg/kg;

PFHxS at 0.133 J μg/kg; PFNA at 0.344 J μg/kg; and PFBS at 0.026 J μg/kg.

Soil was also sampled from surface soil (0 to 2 feet bgs) at the facility boundary locations MA-02 

and MA-04, which are downgradient of AOI 3. Soil was also sampled from shallow subsurface 

soil with intervals of 2 to 4 feet bgs (MA-04) and 3 to 5 feet bgs (MA-02). PFOA, PFOS, and 

PFHxS were detected in surface soil, at concentrations below their respective SLs. The maximum 

concentrations detected were PFOA at 0.156 J μg/kg; PFOS at 0.246 J μg/kg; PFHxS at 0.114 J 

μg/kg. PFNA and PFBS were not detected in surface soil at either location. PFOS was detected 

in shallow subsurface soil below the SL at 0.074 J μg/kg. PFOA, PFHxS, PFNA, and PFBS were 

not detected in shallow subsurface soil at either location. 
Site Inspection Report

Morrisville Army Aviation Support Facility #1, North Carolina

AECOM 6-5

6.5.2 AOI 3 Groundwater Analytical Results

Table 6-4 summarizes the groundwater results. Figure 6-6 and Figure 6-7 present the ranges of 

detections in groundwater. 

Groundwater was sampled from existing monitoring wells AOI03-MW-Deep and AOI03-MWShallow. PFOA, PFOS, and PFHxS were detected in groundwater, at concentrations above their 

respective SLs. The maximum concentrations detected are as follows:

• PFOA was detected above the SL of 6 ng/L AOI03-MW-Shallow, with a concentration

of 80.0 ng/L. PFOS was detected above the SL of 4 ng/L, with a concentration of 316

ng/L. PFHxS was detected above the SL of 39 ng/L, with a concentration of 1,620 ng/L.

PFNA and PFBS were detected in groundwater at concentrations below their respective

SLs. PFNA was detected at 2.95 J ng/L and PFBS was detected at 534 ng/L.

• PFOA was detected above the SL of 6 ng/L at AOI03-MW-Deep with a concentration of

27.3 ng/L. PFOS was detected above the SL of 4 ng/L, with a concentration of 90.5

ng/L. PFHxS was detected above the SL of 39 ng/L, with a concentration of 406 ng/L.

PFNA and PFBS were detected in groundwater at concentrations below their respective

SLs. PFNA was detected at 1.48 J ng/L and PFBS was detected at 145 ng/L.

Groundwater was also sampled from permanent monitoring wells MA-02 and MA-04, which are 

downgradient of AOI 3. PFOS and PFNA were not detected in groundwater at either location. 

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

The maximum concentrations detected are as follows: 

• PFOA was detected below the SL at location MA-02, with a concentration of 0.816 J

ng/L. PFOS, PFHxS, PFNA, and PFBS were not detected in groundwater.

• PFOA was detected above the SL of 6 ng/L at location MA-04, with a concentration of

6.91 ng/L. PFHxS was detected above the SL of 39 ng/L, with a concentration of 42.0

ng/L. PFBS was detected below the SL, with a concentration of 5.05 ng/L. PFOS and

PFNA were not detected in groundwater.

6.5.3 AOI 3 Conclusions

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

concentrations below their respective SLs. PFOA, PFOS, and PFHxS were detected in 

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

in groundwater, further evaluation at AOI 3 is warranted.

6.6 AOI 4 

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

AOI 4: Hangar. The results in soil and groundwater are presented in Table 6-2 through Table 6-

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

6.6.1 AOI 4 Soil Analytical Results

Table 6-2 and Table 6-3 summarize the soil results. Figure 6-1 through Figure 6-5 present the 

ranges of detections in soil. 

Soil was sampled from surface soil (0 to 2 feet bgs) from boring location AOI04-01. PFOA, PFOS, 

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

PFOA was detected at a concentration of 1.52 μg/kg. PFOS was detected at a concentration of 
Site Inspection Report

Morrisville Army Aviation Support Facility #1, North Carolina

AECOM 6-6

10.9 μg/kg. PFHxS was detected at a concentration of 0.203 J μg/kg. PFNA was detected at a 

concentration of 4.52 μg/kg. PFBS was not detected at location AOI04-01.

Soil was also sampled from surface soil (0 to 2 feet bgs) at the facility boundary locations MA-01 

and MA-03. Soil sample MA-01 was upgradient of AOI 4 and MA-03 was downgradient of AOI 4. 

Soil was also sampled from shallow subsurface soil with intervals of 11 to 13 feet bgs (MA-01) 

and 13 to 15 feet bgs (MA-03). PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in surface 

soil at concentrations below their respective SLs. The maximum concentrations detected were 

PFOA at 0.233 J μg/kg; PFOS at 6.79 μg/kg; PFHxS at 2.96 J μg/kg; PFNA at of 0.040 J μg/kg; 

and PFBS was detected at 0.041 J μg/kg. PFOA, PFOS, PFHxS, PFNA, and PFBS were not 

detected in shallow subsurface soil at either location. 

6.6.2 AOI 4 Groundwater Analytical Results

Table 6-4 summarizes the groundwater results. Figure 6-6 and Figure 6-7 present the ranges of 

detections in groundwater. 

Groundwater was sampled from permanent monitoring wells MA-01 and MA-03. Monitoring well 

MA-01 is upgradient of AOI 4, and MA-03 is downgradient of AOI 4. PFOA, PFOS, and PFHxS 

were detected in groundwater at concentrations above their respective SLs. The maximum 

concentrations detected are as follows:

• PFOS was detected above the SL of 4 ng/L at location MA-01, with a concentration of 

5.40 ng/L. PFOA was detected below the SL of 6 ng/L, with a concentration of 1.28 J 

ng/L. PFHxS was detected below the SL, with a concentration of 8.10 ng/L. PFBS was 

detected below the SL, with a concentration of 1.80 J ng/L. PFNA was not detected in 

groundwater.

• PFOA was detected above the SL of 6 ng/L at location MA-03, with a concentration of 

14.1 ng/L. PFOS was detected above the SL of 4 ng/L, with a concentration 31.9 ng/L. 

PFHxS was detected above the SL of 39 ng/L, with a concentration of 109 ng/L. PFBS 

was detected below the SL with a concentration of 23.9 ng/L. PFNA was not detected 

in groundwater.

6.6.3 AOI 4 Conclusions

Based on the results of the SI, PFOA, PFOS, PFHxS, and PFNA were detected at concentrations 

below their respective SLs in surface soil. PFOS was detected in groundwater at a concentration 

above its respective SL at location MA-01, upgradient of AOI 4. PFOA, PFOS, and PFHxS, were 

detected in groundwater at concentrations above their respective SLs at location MA-03, 

downgradient of AOI 4. Based on the exceedances of the SLs groundwater at locations upgradient 

and downgradient of AOI 4, further evaluation at AOI 4 is warranted.

6.7 AOI 5

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

AOI 5: Long-Term Tri-Max 30TM Storage Area. The results in soil and groundwater are presented 

in Table 6-2 through Table 6-4. Soil and groundwater results are presented on Figure 6-1 through 

Figure 6-7.

6.7.1 AOI 5 Soil Analytical Results

Table 6-2 and Table 6-3 summarize the soil results. Figure 6-1 through Figure 6-5 present the 

ranges of detections in soil. 
Site Inspection Report

Morrisville Army Aviation Support Facility #1, North Carolina

AECOM 6-7

Soil was sampled from surface soil (0 to 2 feet bgs) from boring location AOI05-01. PFOA, PFOS, 

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

The maximum concentrations detected were PFOA at 0.646 J μg/kg; PFOS at 0.695 J μg/kg; 

PFHxS at 0.122 J μg/kg; and PFNA at 1.22 J μg/kg. PFBS was not detected at location AOI05-

01.

Soil was also sampled from surface soil (0 to 2 feet bgs) at the facility boundary locations MA-01 

and MA-03. Soil sample MA-01 was upgradient of AOI 5 and MA-03 was downgradient of AOI 5. 

Soil was also sampled from shallow subsurface soil with intervals of 11 to 13 feet bgs (MA-01) 

and 13 to 15 feet bgs (MA-03). PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in surface 

soil at concentrations below their respective SLs. The maximum concentrations detected were 

PFOA at 0.233 J μg/kg; PFOS at 6.79 μg/kg; PFHxS at 2.96 J μg/kg; PFNA at of 0.040 J μg/kg; 

and PFBS was detected at 0.041 J μg/kg. PFOA, PFOS, PFHxS, PFNA, and PFBS were not 

detected in shallow subsurface soil at either location.

6.7.2 AOI 5 Groundwater Analytical Results 

Table 6-4 summarizes the groundwater results. Figure 6-6 and Figure 6-7 present the ranges of 

detections in groundwater. 

Groundwater was sampled from permanent monitoring wells MA-01 and MA-03. Monitoring well 

MA-01 is upgradient of AOI 5, and MA-03 is downgradient of AOI 5. PFOA, PFOS, and PFHxS 

were detected in groundwater at concentrations above their respective SLs. The maximum 

concentrations detected are as follows:

• PFOS was detected above the SL of 4 ng/L at location MA-01, with a concentration of

5.40 ng/L. PFOA was detected below the SL, with a concentration of 1.28 J ng/L. PFHxS

was detected below the SL, with a concentration of 8.10 ng/L. PFBS was detected

below the SL, with a concentration of 1.80 J ng/L. PFNA was not detected in

groundwater.

• PFOA was detected above the SL of 6 ng/L at location MA-03, with a concentration of

14.1 ng/L. PFOS was detected above the SL of 4 ng/L with a concentration 31.9 ng/L.

PFHxS was detected above the SL of 39 ng/L, with a concentration of 109 ng/L. PFBS

was detected below the SL a concentration of 23.9 ng/L. PFNA was not detected in

groundwater.

6.7.3 AOI 5 Conclusions

Based on the results of the SI, PFOA, PFOS, PFHxS, and PFNA were detected at concentrations 

below their respective SLs in surface soil. PFOS was detected in groundwater, at a concentration 

above its SL at location MA-01, upgradient of AOI 5. PFOA, PFOS, and PFHxS, were detected in 

groundwater at concentrations above their respective SLs at location MA-03, downgradient of AOI 

5. Based on the exceedances of the SLs groundwater at locations upgradient and downgradient

of AOI 5, further evaluation at AOI 5 is warranted.
Site Inspection Report

Morrisville Army Aviation Support Facility #1, North Carolina

AECOM 6-8

THIS PAGE INTENTIONALLY BLANK
Table 6-2

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

Site Inspection Report, Morrisville AASF #1

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Resu

PFBS 1900 ND U 0.056 J 0.027 J 0.054 J 0.097 J 0.084 J ND UJ 0.045 J 0.026 PFHxS 130 0.077 J 1.37 0.164 J 3.34 1.14 0.896 J 0.061 J 0.340 J 0.133 

PFNA 19 ND U 3.56 0.133 J 0.802 J 0.636 J 0.882 J ND U 57.3 0.344 

PFOA 19 ND U 3.78 ND U 3.90 0.970 J 0.435 J ND UJ 32.5 0.232 

PFOS 13 0.239 J 3.40 2.52 1.57 6.67 5.31 J 0.072 J 2.03 1.59 

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acidPFOA perfluorooctanoic acidPFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AASF Army Aviation Support FacilityJ+ = Estimated concentration, biased high AOI Area of Interest

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

DL detection limitft feetHQ hazard quotientID identificationLCMSMS liquid chromatography with tandem mLOD limit of detectionMA Morrisville AASF #1ND analyte not detected above the LODOSD Office of the Secretary of DefenseQSM Quality Systems ManualQual interpreted qualifierSB soil boringUSEPA United States Environmental Protectioμg/kg micrograms per kilogram

AOI01-04-SB-00-02

12/06/2021

AOI01-02-SB-00-02

12/07/2021

0-2 ft

AOI01-03-SB-00-02

12/06/2021

0-2 ft

AOI02

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

0-2 ft

AOI01-05-00-02

12/10/2021

0-2 ft

12/16/2021

0-2 ft

Area of Interest

Sample ID

Sample Date

Depth

AOI01-01-SB-00-02

12/14/2021

0-2 ft

AOI01 

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

AOI02-02-SB-00-02

12/07/2021

0-2 ft

AOI03

1

AOI02-01-SB-00-02 AOI02-01-SB-00-02-D

12/16/2021

0-2 ft

AECOM 
Table 6-2

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

Site Inspection Report, Morrisville AASF #1

Analyte OSD Screening 

Level a

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

PFBS 1900 ND U 0.041 J ND U ND U ND U ND UPFHxS 130 0.122 J 0.207 J 0.114 J 0.221 J 0.296 J ND UPFNA 19 1.22 J ND U ND U 0.040 J 0.035 J ND UPFOA 19 0.646 J ND U 0.156 J 0.209 J 0.233 J ND UPFOS 13 0.695 J 0.323 J+ 0.246 J 6.79 6.54 0.098 J

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acidPFOA perfluorooctanoic acidPFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AASF Army Aviation Support FacilityJ+ = Estimated concentration, biased high AOI Area of Interest

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

DL detection limitft feetHQ hazard quotientID identificationLCMSMS liquid chromatography with tandem mLOD limit of detectionMA Morrisville AASF #1ND analyte not detected above the LODOSD Office of the Secretary of DefenseQSM Quality Systems ManualQual interpreted qualifierSB soil boringUSEPA United States Environmental Protectioμg/kg micrograms per kilogram

12/09/2021

0-2 ft

Area of Interest

Sample ID

Sample Date

Depth

AOI05

AOI05-01-SB-00-02

12/07/2021

0-2 ft

Facility Boundary

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

MA-04-SB-00-02

12/09/2021

0-2 ft

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

MA-03-SB-00-02

12/07/2021

0-2 ft

MA-03-SB-00-02-D

12/07/2021

0-2 ft

MA-01-SB-00-02

12/06/2021

0-2 ft

MA-02-SB-00-02

AECOM 
Table 6-3

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

Site Inspection Report, Morrisville AASF #1

Analyte OSD Screening 

Level a

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

PFBS 25000 0.039 J ND U ND U ND U ND U ND UPFHxS 1600 0.101 J ND U ND U ND U ND U ND UPFNA 250 ND U ND U ND U ND U ND U ND UPFOA 250 ND U ND U ND U ND U ND U ND UPFOS 160 ND U ND U ND U ND U ND U 0.074 J

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acidPFOA perfluorooctanoic acidPFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

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

D duplicateDL detection limitft feetHQ hazard quotientID identificationLCMSMS liquid chromatography with tandem mLOD limit of detectionMA Morrisville AASF #1ND analyte not detected above the LODOSD Office of the Secretary of DefenseQSM Quality Systems ManualQual interpreted qualifierSB soil boringUSEPA United States Environmental Protectioμg/kg micrograms per kilogram

MA-01-SB-11-13

12/06/2021

11-13 ft

Area of Interest

Sample ID

Sample Date

Depth

AOI01

AOI01-01-SB-13-15

12/16/2021

13-15 ft

Facility Boundary

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

MA-04-SB-02-04

12/09/2021

2-4 ft

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

MA-02-SB-03-05

12/09/2021

3-5 ft

MA-03-SB-13-15

12/07/2021

13-15 ft

AOI02

AOI02-01-SB-13-15

12/16/2021

13-15 ft

AECOM 
Table 6-4

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

Site Inspection Report, Morrisville AASF #1

Analyte OSD Screening 

Level a

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

PFBS 601 32.9 6.62 7.49 145 534 1.80 J ND U 23.9 

PFHxS 39 73.3 32.4 37.2 406 1620 8.10 ND U 109 

PFNA 6 ND U ND U ND U 1.48 J 2.95 J ND U ND U ND U 

PFOA 6 4.76 6.80 7.96 27.3 80.0 1.28 J 0.816 J 14.1 

PFOS 4 ND U ND U ND U 90.5 316 5.40 ND U 31.9 

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic a

References PFHxS perfluorohexanesulfonic a

PFNA perfluorononanoic acidPFOA perfluorooctanoic acidPFOS perfluorooctanesulfonic a

Interpreted Qualifiers Acronyms and Abbreviations

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

D duplicateDL detection limitGW groundwaterHQ hazard quotientID identificationLCMSMS liquid chromatography wiLOD limit of detectionMA Morrisville AASF #1ND analyte not detected aboOSD Office of the Secretary of QSM Quality Systems ManualQual interpreted qualifierUSEPA United States Environmeng/l nanogram per liter

Area of Interest Facility Boundary

Sample ID

Sample Date

AOI01

AOI01-01-GW

12/30/2021 12/07/2021

AOI03-MW-SHALLOW-GW

12/07/2021

AOI02-01-GW

12/30/2021

AOI02-01-GW-D

12/30/2021

AOI02 AOI03

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

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

MA-03-GW12/13/2021

MA-01-GW12/14/2021

MA-02-GW12/30/2021

AOI03-MW-DEEP-GW

AECOM 
AOI01-01

AOI02-01

MA-01

MA-02

MA-03

MA-04

AOI01-04

AOI01-05

AOI01-02 AOI01-03

AOI03-01

AOI02-02

AOI04-01

AOI05-01

Haleys Branch

0 190 380 760

Feet

Figure 6-1

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Morrisville AASF #1, NC

8/26/2022

8/26/2022

8/26/2022

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PFOA Detections in Soil

12420 Milestone Center Drive

Germantown, MD 20876

Legend

Facility Boundary

Water Body

River/Stream

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

1:4,560 ­

Haleys Branch

AOI01-01

AOI02-01

MA-01

MA-02

MA-03

MA-04

Shallow Intermediate

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

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

PROJECT

PFOA Results (μg/Kg)

ND

>ND - 19

>19 - 250

>250 - 2,500

>2,500

AECOM 6-13
AOI01-01

AOI02-01

MA-01

MA-02

MA-03

MA-04

AOI01-04

AOI01-05

AOI01-03

AOI01-02

AOI03-01

AOI02-02

AOI04-01

AOI05-01

Haleys Branch

0 190 380 760

Feet

Figure 6-2

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Morrisville AASF #1, NC

8/26/2022

8/26/2022

8/26/2022

MS

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8/26/2022

PFOS Detections in Soil

12420 Milestone Center Drive

Germantown, MD 20876

Legend

Facility Boundary

Water Body

River/Stream

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

1:4,560 ­

Haleys Branch

AOI01-01

AOI02-01

MA-01

MA-02

MA-03

MA-04

Shallow Intermediate

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

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

PROJECT

PFOS Results (μg/Kg)

ND

>ND - 13

>13 - 160

>160 - 1,600

>1,600

AECOM 6-14
AOI01-01

AOI02-01

MA-01

MA-02

MA-03

MA-04

AOI01-04

AOI01-05

AOI01-03

AOI01-02

AOI03-01

AOI02-02

AOI04-01

AOI05-01

Haleys Branch

0 190 380 760

Feet

Figure 6-3

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Morrisville AASF #1, NC

8/26/2022

8/26/2022

8/26/2022

MS

MB

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8/26/2022

PFBS Detections in Soil

12420 Milestone Center Drive

Germantown, MD 20876

Legend

Facility Boundary

Water Body

River/Stream

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

1:4,560 ­

Haleys Branch

AOI01-01

AOI02-01

MA-01

MA-02

MA-03

MA-04

Shallow Intermediate

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

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

PROJECT

PFBS Results (μg/Kg)

ND

>ND - 10

>10 - 1,900

>1,900 - 25,000

>25,000

AECOM 6-15
AOI01-01

AOI02-01

MA-01

MA-02

MA-03

MA-04

AOI01-04

AOI01-05

AOI01-03 AOI01-02

AOI03-01

AOI02-02

AOI04-01

AOI05-01

Haleys Branch

0 190 380 760

Feet

Figure 6-4

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Morrisville AASF #1, NC

8/26/2022

8/26/2022

8/26/2022

MS

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8/26/2022

PFHxS Detections in Soil

12420 Milestone Center Drive

Germantown, MD 20876

Legend

Facility Boundary

Water Body

River/Stream

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

1:4,560 ­

Haleys Branch

AOI01-01

AOI02-01

MA-01

MA-02

MA-03

MA-04

Shallow Intermediate

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

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

PROJECT

PFHxS Results (μg/Kg)

ND

>ND - 10

>10 - 130

>130 - 1,600

>1,600

AECOM 6-16
AOI01-01

AOI02-01

MA-01

MA-02

MA-03

MA-04

AOI01-04

AOI01-05

AOI01-03 AOI01-02

AOI03-01

AOI02-02

AOI04-01

AOI05-01

Haleys Branch

0 190 380 760

Feet

Figure 6-5

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Morrisville AASF #1, NC

8/26/2022

8/26/2022

8/26/2022

MS

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8/26/2022

PFNA Detections in Soil

12420 Milestone Center Drive

Germantown, MD 20876

Legend

Facility Boundary

Water Body

River/Stream

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

1:4,560 ­

Haleys Branch

AOI01-01

AOI02-01

MA-01

MA-02

MA-03

MA-04

Shallow Intermediate

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

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

PROJECT

PFNA Results (μg/Kg)

ND

>ND - 19

>19 - 250

>250 - 2,500

>2,500

AECOM 6-17
RDU Washrack

AOI01-01

AOI02-01

AOI03-MW-DEEP

145 ng/L

AOI03-MW-SHALLOW

534 ng/L

MA-01

MA-02

MA-03

MA-04

Haleys Branch

AOI01-01

AOI02-01

AOI03-MW-DEEP

27.3 ng/L

AOI03-MW-SHALLOW

80 ng/L

MA-01

MA-02

MA-03

MA-04

Haleys Branch

0 190 380 760

Feet

Figure 6-6

CLIENT

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SCALE

PROJECT

ARNG

Site Inspection at Morrisville AASF #1, NC

10/13/2022

10/13/2022

10/13/2022

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10/13/2022

PFOA, PFOS, and PFBS Detections in Groundwater

12420 Milestone Center Drive

Germantown, MD 20876

Facility Boundary

Water Body

River/Stream

Groundwater Flow Direction

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

1:4,560 ­

RDU Washrack

AOI01-01

AOI02-01

AOI03-MW-DEEP

90.5 ng/L

AOI03-MW-SHALLOW

316 ng/L

MA-01

MA-02

MA-03

MA-04

Haleys Branch

PFOA PFOS PFBS

PFOA Results (ng/L)

ND

>ND - 6

>6 - 40

>40 - 70

>70

PFOS Results (ng/L)

ND

>ND - 4

>4 - 40

>40 - 70

>70

PFBS Results (ng/L)

ND

>ND - 100

>100 - 601

>601 - 2,000

>2,000

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

AECOM 6-18
RDU Washrack

AOI01-01

AOI02-01

AOI03-MW-DEEP

1.48 ng/L

AOI03-MW-SHALLOW

2.95 ng/L

MA-01

MA-02

MA-03

MA-04

Haleys Branch

AOI01-01

AOI02-01

AOI03-MW-DEEP

406 ng/L

AOI03-MW-SHALLOW

1620 ng/L

MA-01

MA-02

MA-03

MA-04

Haleys Branch

0 190 380 760

Feet

Figure 6-7

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection at Morrisville AASF #1, NC

9/13/2022

9/13/2022

9/13/2022

MS

MB

CM

GIS BY

CHK BY

PM

9/13/2022

PFHxS and PFNA Detections in Groundwater

12420 Milestone Center Drive

Germantown, MD 20876

Facility Boundary

Water Body

River/Stream

Groundwater Flow Direction

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

1:4,560 ­

PFHxS PFNA

PFHxS Results (ng/L)

ND

>ND - 39

>39 - 100

>100 - 1,000

>1,000

PFNA Results (ng/L)

ND

>ND - 6

>6 - 100

>100 - 1,000

>1,000

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

AECOM 6-19
THIS PAGE INTENTIONALLY BLANK

6-20
Site Inspection Report

Morrisville Army Aviation Support Facility #1, North Carolina

AECOM 7-1

7. Exposure Pathways

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

Figure 7-3. 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; and

5. Potentially exposed populations.

If any of these elements are missing, the pathway is incomplete. The CSM figures use an empty 

circle symbol to represent an incomplete exposure pathway. Areas with an incomplete pathway 

generally warrant no further action. However, the pathway is considered potentially complete if the 

relevant compounds are detected, in which case the CSM figure uses a half-filled circle symbol to 

represent a potentially complete exposure pathway. Additionally, a completely filled circle symbol is 

used to indicate when a potentially complete exposure pathway has detections of relevant 

compounds above the SLs. Areas with an identified potentially complete pathway that have 

detections of the relevant compounds above the SLs may warrant further investigation. Although 

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

recommendation for future study in an RI or no action at this time is based on the comparison of 

the SI analytical results for the relevant compounds to the SLs.

In general, the potential routes of exposure to the relevant compounds are ingestion and 

inhalation. Human exposure via the dermal contact pathway may occur, and current risk practice 

suggests it is an insignificant pathway compared to ingestion; however, exposure data for dermal 

pathways are sparse and continue to be the subject of toxicological study. The receptors 

evaluated are consistent with those listed in USEPA guidance for risk screening (USEPA, 2001). 

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

workers, trespassers, residents outside the facility boundary, and recreational users outside of 

the facility boundary. 

7.1 Soil Exposure Pathway

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

between the source and potential receptors at AOI 1 through AOI 5 based on the aforementioned 

criteria. 

7.1.1 AOI 1 

AOI 1 is the Wash Rack Area, where AFFF releases may have occurred during fire training 

activities and Tri-Max unit maintenance. 

PFOA, PFOS, PFHxS, PFNA, and PFBS were detected below their respective SLs in surface soil 

at AOI 1. Site workers and construction workers could contact constituents in surface soil via 
Site Inspection Report

Morrisville Army Aviation Support Facility #1, North Carolina

AECOM 7-2

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

workers and construction workers are potentially complete. PFHxS and PFBS were detected

below their respective SLs in subsurface soil at AOI 1. Construction workers could contact 

constituents in subsurface soil via incidental ingestion; therefore, the subsurface soil exposure 

pathway for construction workers is potentially complete. The CSM for AOI 1 is presented on 

Figure 7-1. 

7.1.2 AOI 2

AOI 2 encompasses the long grassy area along Delta Row was the targeted area for AFFF training 

with Tri-Max 30TM carts. The Delta Row FTA was active from the 1988 to 2010, with regular training 

occurring approximately once every 2 years.

PFOA and PFNA were detected above their respective SLs in surface soil at AOI 2. Site workers 

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

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

workers are potentially complete. PFOA, PFOS, PFHxS, PFNA, and PFBS were not detected in 

subsurface soil at AOI 2; therefore, all exposure pathways are considered incomplete. The CSM

for AOI 2 is presented on Figure 7-2. 

7.1.3 AOI 3

AOI 3 encompasses the area inside the vehicle bay of the Firehouse, where AFFF is currently 

stored, and the adjacent area to the south, where one firetruck was flushed after an internal AFFF 

leak was discovered. 

PFOA, PFOS, PFHxS, PFNA, and PFBS were detected below their respective SLs in surface soil 

at AOI 3. Site workers and construction workers could contact constituents in surface soil via 

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

workers and construction workers are potentially complete. PFOS was detected below its 

respective SL in subsurface soil at location MA-04, downgradient of AOI 3. Construction workers 

could contact constituents in subsurface soil via incidental ingestion; therefore, the subsurface 

soil exposure pathway for construction workers is potentially complete. The CSM for AOI 3 is 

presented on Figure 7-1.

7.1.4 AOI 4

AOI 4 encompasses the Morrisville AASF #1 Hangar, which contains an actively charged AFFF 

dispensing system which developed a leak in 2018, discharging approximately 5 gallons of AFFF. 

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

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

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

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

not detected in subsurface soil at facility boundary locations upgradient or downgradient of AOI 

4; therefore, all subsurface soil exposure pathways are considered incomplete. The CSM for AOI 

4 is presented on Figure 7-3.

7.1.5 AOI 5

AOI 5 encompasses the Long-Term Tri-Max 30TM Storage Area on the gravel north of the 

Morrisville AASF #1 Hangar, where Tri-Max 30TM carts are permanently stored.

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

5. Site workers and construction workers could contact constituents in surface soil via incidental 
Site Inspection Report

Morrisville Army Aviation Support Facility #1, North Carolina

AECOM 7-3

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

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

not detected in subsurface soil at facility boundary locations upgradient or downgradient of AOI 

5; therefore, all subsurface soil exposure pathways are considered incomplete. The CSM for AOI 

5 is presented on Figure 7-3. 

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 was detected above its SL in the groundwater sample collected at AOI 1. The depth to 

water measured at AOI 1 in December 2021 during the SI was 13.50 feet bgs. As a result, 

construction workers could contact constituents in shallow groundwater via incidental ingestion. 

Therefore, the shallow groundwater exposure pathway for construction workers is potentially 

complete. 

Drinking water at Morrisville AASF #1 is provided by the Town of Cary, which sources all of its 

water from the Jordan Lake. The Jordan Lake water intake is located approximately 16 miles 

southwest of the Morrisville AASF #1 facility (Town of Cary, 2018). Several public supply wells 

exist within 4 miles of the facility to the east, northeast, and southeast. These wells are crossgradient and upgradient of the facility and not likely to be influenced by potential releases at 

Morrisville AASF #1. Therefore, the ingestion exposure pathway for site workers and residents is 

considered incomplete. The CSM for AOI 1 is presented on Figure 7-1. 

7.2.2 AOI 2 

PFOA was detected above its SL in the groundwater sample collected at AOI 2. The depth to 

water measured at AOI 2 in December 2021 during the SI was 10.38 feet bgs. As a result, 

construction workers could contact constituents in shallow groundwater via incidental ingestion. 

Therefore, the shallow groundwater exposure pathway for construction workers is potentially 

complete. As mentioned in Section 7.2.1 above, due to the groundwater flow direction and 

distance to drinking water receptors, the ingestion exposure pathway for off-facility residents is 

considered incomplete. Since drinking water at the facility is provided by the Town of Cary, the 

ingestion exposure pathway for site workers is considered incomplete. The CSM for AOI 2 is 

presented on Figure 7-2. 

7.2.3 AOI 3 

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

collected at AOI 3. The depth to water measured at AOI 3 in December 2021 during the SI ranged 

from 6.73 to 36.29 feet bgs. As a result, construction workers could contact constituents in shallow 

groundwater via incidental ingestion. Therefore, the shallow groundwater exposure pathway for 

construction workers is potentially complete. As mentioned in Section 7.2.1 above, due to the 

groundwater flow direction and distance to drinking water receptors, the ingestion exposure 

pathway for off-facility residents is considered incomplete. Since drinking water at the facility is 

provided by the Town of Cary, the ingestion exposure pathway for site workers is considered 

incomplete. The CSM for AOI 3 is presented on Figure 7-1. 
Site Inspection Report

Morrisville Army Aviation Support Facility #1, North Carolina

AECOM 7-4

7.2.4 AOI 4 

PFOS was detected above its SL in the groundwater sample collected upgradient (MA-01) of AOI 

4. PFOA, PFOS, and PFHxS were detected above their respective SLs in the groundwater sample

collected downgradient (MA-03) of AOI 4. The depth to water measured at the locations

upgradient and downgradient of AOI 4 in December 2021 during the SI ranged from 6.03 to 23.71

feet bgs. As a result, construction workers could contact constituents in shallow groundwater via

incidental ingestion. Therefore, the shallow groundwater exposure pathway for construction

workers is potentially complete. As mentioned in Section 7.2.1 above, due to the groundwater

flow direction and distance to drinking water receptors, the ingestion exposure pathway for offfacility residents is considered incomplete. Since drinking water at the facility is provided by the

Town of Cary, the ingestion exposure pathway for site workers is considered incomplete. The

CSM for AOI 4 is presented on Figure 7-3.

7.2.5 AOI 5 

PFOS was detected above its SL in the groundwater sample collected upgradient (MA-01) of AOI 

5. PFOA, PFOS, and PFHxS were detected above their respective SLs in the groundwater sample

collected downgradient (MA-03) of AOI 5. The depth to water measured at the locations

upgradient and downgradient of AOI 5 in December 2021 during the SI ranged from 6.03 to 23.71

feet bgs. As a result, construction workers could contact constituents in shallow groundwater via

incidental ingestion. Therefore, the shallow groundwater exposure pathway for construction

workers is potentially complete. As mentioned in Section 7.2.1 above, due to the groundwater

flow direction and distance to drinking water receptors, the ingestion exposure pathway for and

off-facility residents is considered incomplete. The CSM for AOI 5 is presented on Figure 7-3.

7.3 Surface Water and Sediment Exposure Pathway

The SI results in soil and groundwater, in combination with knowledge of the fate and transport 

properties of PFAS, were used to determine whether a potentially complete pathway exists 

between the source and potential receptors.

Because PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in soil and groundwater at the 

AOIs, it is possible that those compounds may have migrated from soil and groundwater to Haleys 

Branch via groundwater discharge or the stormwater system outfall. Haleys Branch flows into 

Lake Crabtree, Crabtree Creek, and eventually the Neuse River; therefore, the surface water and 

sediment ingestion exposure pathway for recreational users is considered potentially complete. 

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

Figure 7-3. 
Media

SOURCE PATHWAY RECEPTOR

AOI 1

AOI 3

Fire training, 

AFFF storage, 

AFFF leaks, 

Firetruck 

Flush

Surface Soil

Human 

Activities

Precipitation/ 

Run-Off

Leaching/ 

Infiltration

Airborne Soil 

Particulate

Surface Soil 

at AOI

Surface 

Water/ 

Sediment

Subsurface 

Soil

Shallow 

Groundwater

Source Release 

Mechanism Media Transport and Migration Media Exposure Routes

Inhalation of 

Dust

Ingestion

Ingestion

Ingestion

Ingestion

Human Receptors: 

Current/ Future

Flow-Chart Continues

Partial / Possible Flow

Incomplete Pathway

Potentially Complete Pathway

Potentially Complete Pathway with Exceedance of SL

Site Worker Construction Worker Resident1

Site Worker Construction Worker Resident1

/ / / /

/ / / /

LEGEND

/ / / /

/ / / /

/ / /

Figure 7-1

Conceptual Site Model - AOI 1 and AOI 3

Morrisville AASF #1

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

Recreational User1

Recreational User1 Notes:

1. The resident and recreational user

receptors refer to an off-site resident and

recreational user.

Flow-Chart Stops

/

Precipitation/ 

Run-Off/ 

Sanitary 

Sewer 

Discharge

AECOM 7-5
Media

SOURCE PATHWAY RECEPTOR

AOI 2 Fire training, 

AFFF storage

Surface Soil, 

Sanitary 

Sewer

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

Incomplete Pathway

Potentially Complete Pathway

Potentially Complete Pathway with Exceedance of SL

Site Worker Construction Worker Resident1

Site Worker Construction Worker Resident1

/ / / /

/ / / /

LEGEND

/ / / /

/ / / /

/ / /

Figure 7-2

Conceptual Site Model - AOI 2

Morrisville AASF #1

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

Recreational User1

Recreational User1 Notes:

1. The resident and recreational user

receptors refer to an off-site resident and

recreational user.

Flow-Chart Stops

/

Precipitation/ 

Run-Off/ 

Sanitary 

Sewer 

Discharge

AECOM 7-6
Media

SOURCE PATHWAY RECEPTOR

AOI 4

AOI 5

AFFF storage, 

AFFF leak 

from fire 

suppression 

system

Surface Soil

Human 

Activities

Precipitation/ 

Run-Off

Leaching/ 

Infiltration

Airborne Soil 

Particulate

Surface Soil 

at AOI

Surface 

Water/ 

Sediment

Subsurface 

Soil

Shallow 

Groundwater

Source Release 

Mechanism Media Transport and Migration Media Exposure Routes

Inhalation of 

Dust

Ingestion

Ingestion

Ingestion

Ingestion

Human Receptors: 

Current/ Future

Flow-Chart Continues

Partial / Possible Flow

Incomplete Pathway

Potentially Complete Pathway

Potentially Complete Pathway with Exceedance of SL

Site Worker Construction Worker Resident1

Site Worker Construction Worker Resident1

/ / / /

/ / / /

LEGEND

/ / / /

/ / / /

/ / /

Figure 7-3

Conceptual Site Model - AOI 4 and AOI 5

Morrisville AASF #1

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

Recreational User1

Recreational User1 Notes:

1. The resident and recreational user

receptors refer to an off-site resident and

recreational user.

Flow-Chart Stops

/

Precipitation/ 

Run-Off/ 

Sanitary 

Sewer 

Discharge

AECOM 7-7
AECOM 8-4

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M 7-8
Site Inspection Report

Morrisville Army Aviation Support Facility #1, North Carolina

AECOM 8-1

8. Summary and Outcome

This section summarizes SI activities and findings. The most significant findings are summarized 

in this section and are reproduced directly or abstracted from information contained in this report. 

The outcome provides general and comparative interpretations of the findings relative to the SLs. 

8.1 SI Activities 

The SI field activities were conducted from 2 to 30 December 2021 and consisted of utility clearance, 

sonic soil boring, soil sample collection, permanent monitoring well installation, groundwater sample 

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

Addendum (AECOM, 2021a). 

To fulfill the project DQOs set forth in the approved SI QAPP Addendum (AECOM, 2021a), samples 

were collected and analyzed for a subset of 18 compounds by LC/MS/MS compliant with QSM 5.3 

Table B-15 as follows. 

• Twenty (20) soil samples from 14 boring locations;

• Six groundwater samples from six newly installed permanent monitoring wells;

• Two groundwater samples from two existing permanent monitoring wells; and

• Twenty (20) QA/QC samples.

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

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

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

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

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

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

described in Section 7. 

8.2 Outcome 

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

AOI 2, AOI 3, AOI 4, and AOI 5 (see Table 8-1). Based on the CSMs developed and revised in 

light of the SI findings, there is no potential for exposure to drinking water receptors from the AOIs 

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

concentrations collected during the SI were compared to the project SLs in soil and groundwater, 

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

• At AOI 1:

• PFOA in groundwater exceeded the SL of 6 ng/L at well AOI01-01, with a

concentration of 73.3 ng/L. Based on the results of the SI, further evaluation of AOI

1 is warranted in the RI.

• Additionally, PFOA and PFHxS exceeded their respective SLs at facility boundary

well MA-04, downgradient of AOI 1. PFOA exceeded the SL of 6 ng/L, with a

concentration of 6.91 ng/L. PFHxS exceeded the SL of 39 ng/L, with a concentration

of 42.0 ng/L.

• The detected concentrations of PFOA, PFOS, PFHxS, PFNA, and PFBS in soil at

AOI 1 were below their respective SLs.
Site Inspection Report

Morrisville Army Aviation Support Facility #1, North Carolina

AECOM 8-2

• The detected concentrations of PFOA, PFOS, and PFHxS in soil at facility boundary 

locations MA-02 and MA-04, downgradient of AOI 1, were below their respective SLs. 

• At AOI 2:

• PFOA in groundwater exceeded the SL of 6 ng/L, with a maximum concentration of 

7.96 ng/L in the field duplicate sample (AOI02-01-GW-D). Based on the results of the 

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

• The detected concentration of PFOA in groundwater at facility boundary well MA-02, 

downgradient of AOI 2, was below the respective SL. 

• PFOA and PFNA in surface soil exceeded their respective SLs. PFOA exceeded the 

SL of 19 μg/kg, with a concentration of 32.5 μg/kg at location AOI02-02. PFNA 

exceeded the SL of 19 μg/kg, with a concentration of 57.3 μg/kg at location AOI02-

02. Based on the results of the SI, further evaluation of AOI 2 is warranted in an RI.

• The detected concentrations of PFOA, PFOS, and PFHxS in soil at facility boundary 

location MA-02, downgradient of AOI 2, were below their respective SLs.

• At AOI 3:

• PFOA, PFOS, and PFHxS in groundwater exceeded their respective SLs. PFOA 

exceeded the SL of 6 ng/L, with a maximum concentration of 80.0 ng/L. PFOS 

exceeded the SL of 4 ng/L, with a maximum concentration of 316 ng/L. PFHxS 

exceeded the SL of 39 ng/L, with a maximum concentration of 1,620 ng/L. Based on 

the results of the SI, further evaluation of AOI 3 is warranted in an RI. 

• Additionally, PFOA and PFHxS exceeded their respective SLs at facility boundary 

well MA-04, downgradient of AOI 3. PFOA exceeded the SL of 6 ng/L, with a 

concentration of 6.91 ng/L. PFHxS exceeded the SL of 39 ng/L, with a concentration 

of 42.0 ng/L.

• The detected concentrations of PFOA, PFOS, PFHxS, PFNA, and PFBS in soil at 

AOI 3 were below their respective SLs. 

• The detected concentrations of PFOA, PFOS, and PFHxS in soil at facility boundary 

locations MA-02 and MA-04, downgradient of AOI 3, were below their respective SLs.

• At AOI 4: 

• PFOA, PFOS, and PFHxS in groundwater exceeded their respective SLs at facility 

boundary wells upgradient and downgradient of AOI 4. PFOA exceeded the SL of 6 

ng/L, with a maximum concentration of 14.1 ng/L at well MA-03. PFOS exceeded the 

SL of 4 ng/L, with a maximum concentration of 31.9 ng/L at well MA-03. PFHxS 

exceeded the SL of 39 ng/L, with a maximum concentration of 109 ng/L at well MA03. Based on the results of the SI, further evaluation of AOI 4 is warranted in an RI. 

• The detected concentrations of PFOA, PFOS, PFHxS, and PFNA in soil at AOI 4

were below their respective SLs. 

• The detected concentrations of PFOA, PFOS, PFHxS, PFNA, and PFBS in soil at 

facility boundary locations upgradient (MA-01) and downgradient (MA-03) of AOI 4

were below their respective SLs.

• At AOI 5: 
Site Inspection Report

Morrisville Army Aviation Support Facility #1, North Carolina

AECOM 8-3

• The detected concentrations of PFOA, PFOS, PFHxS, and PFNA in soil at AOI 5

were below their respective SLs; therefore, no further evaluation of AOI 5 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 Wash Rack Area 

and GSE Building Proceed to RI 

2 Delta Row FTA Proceed to RI

3 Firehouse Storage 

and Flush Area Proceed to RI

4 Hangar Leak Area N/A Proceed to RI

5 Long-Term Tri-Max

30TM Storage Area N/A Proceed to RI

Legend:

= detected; exceedance of the screening levels

= detected; no exceedance of the screening levels

= not detected

N/A = Not Applicable
Site Inspection Report

Morrisville Army Aviation Support Facility #1, North Carolina

AECOM 8-4

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Morrisville Army Aviation Support Facility #1, North Carolina

AECOM 9-1

9. References

AECOM. 2018a. Final Site Inspection Programmatic Uniform Federal Policy-Quality Assurance 

Project Plan, Perfluorooctane Sulfonic Acid (PFOS) and Perfluorooctanoic Acid (PFOA) 

Impacted Sites ARNG Installations, Nationwide Contract No. W912DR-12-D-0014/

W912DR17F0192. 9 March.

AECOM. 2018b. Final Programmatic Accident Prevention Plan, Perfluorooctane Sulfonic Acid 

(PFOS) and Perfluorooctanoic Acid (PFOA) Impacted Sites ARNG Installations, Nationwide 

Contract No. W912DR-12-D-0014/W912DR17F0192. July.

AECOM. 2020. Final Preliminary Assessment Report, Morrisville Army Aviation Support Facility 

#1, North Carolina. August. 

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

Addendum, Morrisville Army Aviation Support Facility #1, North Carolina, Perfluorooctane 

Sulfonic Acid (PFOS) and Perfluorooctanoic Acid (PFOA) Impacted Sites ARNG Installations, 

Nationwide. September.

AECOM. 2021b. Final Site Safety and Health Plan, Morrisville Army Aviation Support Facility #1, 

North Carolina, Perfluorooctane Sulfonic Acid (PFOS) and Perfluorooctanoic Acid (PFOA) 

Impacted Sites ARNG Installations, Nationwide. November.

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

the Department of Defense Cleanup Program. United States Department of Defense. 

6 July. 

Blake, David E. and Clark, Timothy W. 2016. Geologic Map of the Cary 7.5-Minute Quadrangle, 

Wake and Durham Counties, North Carolina. North Carolina Geological Survey, Open File 

Report 2016-02. 

Cawthorn, Joel W. 1970. United States Department of Agriculture (USDA). Soil Survey of Wake 

County, North Carolina.

DA. 2018a. Executive Summary Environmental Health and Engineering Preconstruction 

Assessment No. S.0057366.18-18. 

DA. 2018b. Army Guidance for Addressing Releases of Per- and Polyfluoroalkyl Substances.

4 September.

DoD. 2019a. Department of Defense (DoD), Department of Energy (DOE) Consolidated Quality 

Systems Manual (QSM) for Environmental Laboratories, Version 5.3. 

DoD. 2019b. General Data Validation Guidelines. Environmental Data Quality Workgroup. 

4 November.

EA Engineering, Science, and Technology, Inc. 2021. Standard Operating Procedure No. 042A 

for Treating Liquid Investigation-Derived Material (Purge water, drilling water, and 

decontamination fluids). Revision 1. March.

Guelfo, J.L. and Higgins, C.P. 2013. Subsurface Transport Potential of Perfluoroalkyl Acids at 

Aqueous Film-Forming Foam (AFFF)-Impacted Sites. Environmental Science and Technology 

47(9): 4164-71.

Heath, Ralph C. United States Department of the Interior Geological Survey (USGS). 1980. Basic 

Elements of Ground-Water Hydrology with Reference to Conditions in North Carolina. WaterResources Investigations, Open-File Report 80-44. 
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Morrisville Army Aviation Support Facility #1, North Carolina

AECOM 9-2

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

sediments. Environmental Science and Technology 40 (23): 7251-7256.

Hoffman, Charles W. and Gallagher, Patricia E. 1989. Geology of the Southeast Durham and 

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