FINAL

Site Inspection Report

Army Aviation Support Facility #3

Meridian, Mississippi 

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

July 2023 

Prepared for:

Army National Guard Bureau

111 S. George Mason Drive

Arlington, VA 22204

UNCLASSIFIED
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Army Aviation Support Facility #3, Meridian, Mississippi 

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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......................................................................2-3

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

2.3 History of PFAS Use..............................................................................................2-3

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

3.1 AOI 1.....................................................................................................................3-1

3.2 AOI 2.....................................................................................................................3-1

3.3 Adjacent Sources ..................................................................................................3-1

3.3.1 Key Field.....................................................................................................3-1

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 Temporary Well Installation and Groundwater Grab Sampling...............................5-3

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

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

5.6 Investigation-Derived Waste..................................................................................5-4

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

5.8 Deviations from the 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

6.3.3 AOI 1 Conclusions ......................................................................................6-3
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6.4 AOI 2.....................................................................................................................6-3

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

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

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

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

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

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

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

7.3 Surface Water and Sediment Exposure Pathway ..................................................7-3

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

7.3.2 AOI 2...........................................................................................................7-3

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. Field Change Request Forms

B4. Survey Data

Appendix C Photographic Log

Appendix D TPP Meeting Minutes

Appendix E Boring Logs

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, April 2022

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

Figure 7-2 Conceptual Site Model, AOI 2

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, Temporary 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

°C degrees Celsius

°F degrees Fahrenheit

μg/kg micrograms per kilogram

AASF Army Aviation Support Facility

AECOM AECOM Technical Services, Inc.

AFFF aqueous film-forming foam

ANG Air National Guard

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

DOT Department of Transportation

DPT direct push technology

DQO data quality objective

DUA data usability assessment

EDRTM Environmental Data Resources, Inc.TM

ELAP Environmental Laboratory Accreditation Program

EM Engineer Manual

GPRS Ground Penetrating Radar Systems, LLC

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

MSARNG Mississippi Army National Guard

NELAP National Environmental Laboratory Accreditation Program

ng/L nanograms per liter

OSD Office of the Secretary of Defense

OWS oil/water separator

PA Preliminary Assessment

PFAS per- and polyfluoroalkyl substances

PFBS perfluorobutanesulfonic acid

PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

PID photoionization detector
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PQAPP Programmatic UFP-QAPP

PVC polyvinyl chloride

QA quality assurance

QAPP Quality Assurance Project Plan

QC quality control

QSM Quality Systems Manual

RI Remedial Investigation

SI Site Inspection

SL screening level

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

WWTP wastewater treatment plant
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Army Aviation Support Facility #3, Meridian, Mississippi

AECOM ES-1

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

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

of the SI is to identify whether there has been a release to the environment from theAOIs 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 Army Aviation Support Facility (AASF) #3 in Meridian,

Mississippi and determined further evaluation under the Comprehensive Environmental 

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

#3 will also be referred to as the “facility” throughout this document.

AASF #3 is located southwest of the City of Meridian, Mississippi. The facility is primarily in 

Lauderdale County, Mississippi, approximately 19 miles west of the Mississippi-Alabama Border. 

The facility is 3.5 acres in size and houses the B Company 111th. Seven buildings are located at 

the facility, including a hangar; storage, administration, hazardous material and used oil buildings; 

and a fire pump house. The facility provides aviation and maintenance support primarily for 

helicopters. The property is leased by the State of Mississippi from the Meridian Airport Authority.

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

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

for AOI 1 and AOI 2.

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, as screening values were established after SI planning and execution. 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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Army Aviation Support Facility #3, Meridian, Mississippi 

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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. 

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. 

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

AOI Potential 

Release Area

Soil –

Source Areaa

Groundwater –

Source Areaa

Groundwater –

Facility Boundary

Future 

Action

1 Release Area A

14.9 μg/kg (PFNA) 3,160 ng/L (PFOA) 70.8 ng/L (PFHxS)

Proceed to 

RI 

2 Release Area B

2.67 μg/kg (PFOS) 594 ng/L (PFOS) 70.8 ng/L (PFHxS)

Proceed to 

RI

Notes:

AOI = area of interest; ng/L = nanograms per liter; μg/kg = micrograms per kilogram

a.) The maximum relevant compound concentration is reported at each AOI. 

Legend:

= detected; exceedance of the screening levels

= detected; no exceedance of the screening levels

= not detected
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Army Aviation Support Facility #3, Meridian, Mississippi

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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 Meridian Army

Aviation Support Facility (AASF) in Meridian, Mississippi. AASF #3 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 AASF #3 (AECOM Technical Services, Inc. [AECOM], 2020) that identified

two Areas 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

AASF #3 is located southwest of the City of Meridian, Mississippi (Figure 2-1). The facility is

primarily in Lauderdale County, Mississippi, approximately 19 miles west of the MississippiAlabama Border. The facility is 3.5 acres in size houses the B Company 111th. Seven buildings

are located at the facility, including a hangar; storage, administration, hazardous material and

used oil buildings; and a fire pump house. The facility provides aviation and maintenance support

primarily for helicopters. The facility was established in 1979, and the property is leased by the

State of Mississippi from the Meridian Airport Authority; the current lease is valid until 31 August

2061.

2.2 Facility Environmental Setting

Lauderdale County is located in the Atlantic Plain Physiographic Region, which runs along the

eastern and southern coast of the US, extending from Massachusetts down to the Gulf of Mexico.

The Atlantic Plain is separated into two provinces, the continental shelf beyond the coastline, and

the interior portion known as the Coastal Plain, the inner edge of which is commonly accepted to

be the extent of Cretaceous or Tertiary deposits (Fenneman, 1917). The facility is situated in the

East Gulf Coastal Plain, a belted section of the Coastal Plain between the Mississippian Alluvial

Plain and the Floridian Section that drains to the Gulf of Mexico (Fenneman, 1928). AASF #3 is 

relatively flat and predominately covered by impermeable surfaces that consist of asphalt, 

concrete, and tarmac. However, the ground surface in the eastern and western portion facilities 

consists of grassed land. The topography of the facility is presented on Figure 2-2.

2.2.1 Geology

The main geologic formation underlying the facility is the Wilcox Group (Figure 2-3). The Wilcox 

Group comprises, in stratigraphic order, the Hatchetigbee, Tuscahoma, and Nanafalia formations, 

which correspond to the Upper, Middle, and Lower Wilcox. The Hatchetigbee Formation consists

of regressive nonmarine sediments, gray to brown cross-bedded sands, and lignitic clay. The 

formation has been eroded away beneath the facility to an approximate thickness of several

dozen feet (Leidos, 2019). Underlying the Hatchetigbee Formation is the gray lignitic sand of the

Tuscahoma Formation. The Tuscahoma Formation is often laminated with gray clay and

fossiliferous marls and reaches a thickness of approximately 350 feet. The Nanafalia Formation

underlies the Tuscahoma Formation and consists of buff-colored, fossiliferous, glauconitic,

calcareous sands, dark lignitic silt, clay and some gravel. The Nanafalia Formation is

approximately 300 feet thick (CH2M Hill, 1992). The Wilcox Group has not been significantly

structurally deformed but does have a gentle regional dip of 25 to 30 feet per mile to the southsoutheast (Leidos, 2019).

AASF #3 is located on a thin deposit of Quaternary floodplain alluvium. The soil underlying the 

facility is approximately 6 feet of fine sandy loam, which is the start of the Wilcox Group. This soil 

has been disturbed during historical construction activities. Unaltered soil in the uplands is loamy 

and clayey, well-drained, and typically highly acidic (Allgood, 1983). 

During the SI, soil borings were completed to depths between 4 to 15 feet below ground surface

(bgs). Fine-grained clayey sand and silts were observed as the dominant lithology of the 

unconsolidated sediments below AASF #3. The clayey sands were noted from surface elevations

up to 13 feet bgs. Where identified, the silts were observed as shallow as 5 feet bgs to as deep 

as 15 feet bgs. Varying quantities of fine- to medium-grained sand were observed in all borings

at nearly all depths. Lean clay was observed at AOI02-05 (8.5 to 10 feet bgs) near the southern 
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Army Aviation Support Facility #3, Meridian, Mississippi

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boundary of the facility and MER-01 (3 to 8 feet bgs), along the northern boundary. Poorly graded 

sand was observed at the bottom of borings AOI01-02 (13 to 15 feet bgs) and AOI02-02 (8 to 10 

feet bgs), located along the southern boundary of the facility. The sandy and clayey soils observed 

within the borings are consistent with the nonmarine sediments of the Hatchetigbee Formation. 

Boring logs are presented in Appendix E.

2.2.2 Hydrogeology

The Middle and Lower Wilcox (Tuscahoma and Nanafalia formations, respectively) are the

principal aquifers in the area. An Environmental Data Resources, Inc.TM [EDRTM] report included

a well search for a 1-mile radius surrounding the facility and listed 49 registered state and federal

wells, with 88 percent (%) of the wells situated within these two formations. Wells within the Lower

Wilcox are set from 740 to 870 feet bgs. Static water levels measured in the 1970s and 1980s

within these wells are typically 12 to 21 feet bgs. Wells within the Middle Wilcox aquifer are set

from 240 to 400 feet bgs; static water levels were measured from 42 to 78 feet bgs (EDRTM, 2019).

The facility is supplied potable water by the City of Meridian, which is sourced from eight potable 

wells screened within the Lower Wilcox aquifer. The city does not provide the precise or 

approximate locations of these water supply wells; however, their depths range from 747 to 948 

feet bgs (City of Meridian, 2021). There are no reported confining layers within the Wilcox Group 

(US Geological Survey [USGS], 1998).

Using additional online resources, such as state and local Geographic Information System 

databases, wells were researched in a 4-mile radius of the facility. Well data from the USGS show 

one industrial well, six domestic wells, and 28 wells of unknown purpose within 4 miles 

downgradient of the facility (USGS, 2019). The domestic and unknown wells are drilled to depths 

of at least 135 feet bgs and screened in the Wilcox aquifers (Mississippi Automated Resource 

Information System, 2009). Approximately 2.5 to 3.5 miles to the south, southeast, and southwest 

of the facility, there are domestic wells that range in depth from 191 to 420 feet bgs (Leidos, 2019).

Several shallow monitoring wells (15 to 27 feet bgs) are set within the Hatchetigbee Formation,

about 1 mile to the south, in the center of Key Field, an adjacent Air National Guard (ANG) Base

(Leidos, 2019). The groundwater within the Wilcox Group flows to the south-southwest, following

the structural dip of the formation; however, local variations in flow direction were noted at Key 

Field, where groundwater flow is to the west. Groundwater flow direction at AASF #3 was

approximated to follow a similar south to west trend.

Depths to water measured in April 2022 during the SI ranged from 2.33 to 5.56 feet bgs, with the 

shallowest groundwater encountered in the northern portion of the facility. Groundwater elevation

contours from the SI are presented on Figure 2-4 and indicate the groundwater flow direction at

AASF #3 is primarily to the west, consistent with the regional flow directions noted above.

2.2.3 Hydrology

Regionally, AASF #3 lies within the Burwell Creek-Okatibbee Creek Watershed. Okatibbee Creek 

is located approximately 0.25 miles west of the facility and is fed by Burwell Creek as well as other 

tributaries. Okatibbee Creek is fed by Lake Okatibbee, a lacustrine body covering about 5.5 

square miles. Lake Okatibbee is located approximately 10 miles north of the facility. The 

Okatibbee Creek flows into the Chickasawhay River. Chickasawhay River is used for both smallsize boating and fishing (Natural Atlas, Inc., 2022; The Meridian Star, 2010).

Surface drainage flows across the site to the west-northwest, towards Okatibbee Creek and

several emergent wetlands via three outfalls. Outfall 001 receives and discharges water from the 

North Apron and is located northwest of the North Apron. Outfall 002 receives and discharges 

water from the South Apron and the storm sewer system. Outfall 003 receives water from a 

drainage swale south of the South Apron. Outfalls 002 and 003 are located in a drainage ditch to
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Army Aviation Support Facility #3, Meridian, Mississippi

AECOM 2-3

the west of the south apron and receive water from the South (Bhate Associates, 2011; Mississippi 

ARNG [MSARNG], 2017). According to the National Wetlands Inventory, there are two small 

emergent wetland bodies within and immediately west of the facility’s western boundary. 

Additionally, an excavated lacustrine waterbody is located along the length of Key Field to the

west (US Fish and Wildlife Service [USFWS], 2019). Surface water features are presented on

Figure 2-5.

2.2.4 Climate

Mississippi is located in the humid subtropical climate region and is characterized by temperate 

winters and long, hot summers (Mississippi State University, 2022). Summer temperatures in 

Meridian reach an average maximum of 92 degrees Fahrenheit (°F), with July being the hottest 

month. The coldest month in Meridian is January, with average maximum temperature of 56 °F 

and an average minimum temperature of 33 °F. Meridian averages an annual 56.19 inches of

precipitation. Higher precipitation is generally reported between the months of January through 

March, July, and December. Snowfall in Mississippi is rare (World Climate, 2022).

2.2.5 Current and Future Land Use

The facility has a controlled access gate and is adjacent to Key Field and the Meridian Regional

Airport. The facility provides aviation and maintenance support primarily for helicopters.

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

2.2.6 Sensitive Habitat and Threatened/ Endangered Species

The following mammals, birds, fishes, clams, and insects are federally endangered, threatened,

proposed, and/ or are listed as candidate species in Lauderdale County, Mississippi (USFWS,

2022).

• Mammals: Northern Long-eared Bat, Myotis septentrionalis (Threatened)

• Birds: Wood Stork, Mycteria americana (Threatened)

• Fishes: Pearl Darter, Percina aurora (Threatened)

• Clams: Alabama Moccasinshell, Medionidus acutissimus (Threatened); Orangenacre

Mucket, Hamiota perovalis (Threatened); Ovate Clubshell, Pleurobema perovatum

(Endangered); Southern Clubshell, Pleurobema decisum (Endangered)

• Insects: Monarch Butterfly, Danaus plexippus (Candidate)

2.3 History of PFAS Use

Two AOIs were identified in the PA where AFFF may have been used, stored, disposed, or

released historically at AASF #3 (AECOM, 2020). The onsite hangar is equipped with an AFFF 

fire suppression system. Evidence of leaked/spilled AFFF was observed on the outside of the

AFFF-equipped upright tank during the visual inspection. Additionally, between 2007 to 

2011/2012, approximately 10 portable Tri-MaxTM mobile fire extinguisher units were stationed at 

the wash rack area. The potential release areas were grouped into two AOIs based on preliminary

data and presumed groundwater flow directions. A description of each AOI is presented in

Section 3.
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CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

CD

9/16/2022

9/16/2022

Site Inspection at Meridian AASF, MS

1:63,360

9/16/2022 ­ Figure 2-1 PM CM 9/16/2022

12420 Milestone Center Drive

Germantown, MD 20876

Facility Location

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

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

^_

Meridian AASF

PROJECT

0 0.5 1 2

Miles

Legend

Facility Boundary

AECOM 2-5
CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

CD

9/16/2022

9/16/2022

Site Inspection at Meridian AASF, MS

1:6,000

9/16/2022 ­ Figure 2-2 PM CM 9/16/2022

12420 Milestone Center Drive

Germantown, MD 20876

Facility Topography

Base Map: USGS The National Map: National

Boundaries Dataset, 3DEP Elevation Program,

PROJECT

0 250 500 1,000

Feet

Legend

Facility Boundary

AECOM 2-6
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Figure 2-3

CLIENT

REVISED

SCALE

9/16/2022 MS

CD

9/16/2022

9/16/2022

ARNG

GIS BY

CHK BY

Site Inspection at Meridian AASF, MS

PM CM 9/16/2022

1:95,040 ­ 12420 Milestone Center Drive

Germantown, MD 20876

Base Map: Sources: Esri, HERE, Garmin, USGS, Intermap, INCREMENT P, NRCan, Esri

Japan, METI, Esri China (Hong Kong), Esri Korea, Esri (Thailand), NGCC, (c)

PROJECT

AECOM 2-7
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REVISED

SCALE

ARNG

GIS BY

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11/21/2022

11/21/2022

Site Inspection at Meridian AASF #3, MS

11/21/2022

Figure 2-4 PM CM 11/21/2022

12420 Milestone Center Drive

Germantown, MD 20876

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April 2022

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AECOM 2-8
Burwell Creek

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Figure 2-5

CLIENT

REVISED

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2/9/2023 MS

CD

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2/9/2023

ARNG

GIS BY

CHK BY

Site Inspection at Meridian AASF, MS

PM CM 2/9/2023

1:31,680 ­ 12420 Milestone Center Drive

Germantown, MD 20876

Base Map: Sources: Esri, HERE, Garmin, USGS, Intermap, INCREMENT P, NRCan, Esri

Japan, METI, Esri China (Hong Kong), Esri Korea, Esri (Thailand), NGCC, (c)

PROJECT

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AECOM 2-9
Site Inspection Report

Army Aviation Support Facility #3, Meridian, Mississippi

AECOM 2-10

THIS PAGE INTENTIONALLY BLANK
Site Inspection Report

Army Aviation Support Facility #3, Meridian, Mississippi

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, two AOIs were identified at AASF #3

and are shown on Figure 3-1 (AECOM, 2020).

3.1 AOI 1

AASF #3 hangar (Release Area A) is equipped with an AFFF fire suppression system. The system 

consists of an approximately 500-gallon upright tank that is located outside the hangar and 

connects to the pump room through the wall along the southeast corner. Floor drains within the 

pump room connect to an oil/water separator (OWS) that discharges to the sanitary sewer. The 

sanitary sewer discharges to the City of Meridian’s Wastewater Treatment Plant (WWTP). The 

system was installed in 2007, and initial testing was completed with water only. Since installation,

the system has not been activated; however, the bladder was reportedly replaced by an outside 

contractor between 2015 to 2016. Evidence of leaked/spilled AFFF was observed on the outside

of the tank during the visual site inspection. The volume of AFFF released to the ground

underneath the tank is unknown.

3.2 AOI 2

Between 2007 to 2011/2012, approximately 10 portable Tri-MaxTM units equipped with AFFF were 

kept at AASF #3 and stationed at the wash rack area at Release Area B. The capacity of the units 

and the AFFF concentration within are unknown. According to the PA, a contractor for the State 

of Mississippi emptied the units prior to removing them from the facility (AECOM, 2020). It is

unknown whether the extinguishers were emptied in a way that allowed AFFF to be captured, or

if they were emptied into the wash rack area and allowed to disperse. Had AFFF been emptied in

the vicinity of the wash rack, the potential release pathways for AFFF would be identical to the

pathways described above. AFFF may have drained through the wash rack to the OWS and

subsequently to the Meridian WWTP via the sanitary sewer. Stormwater drains are located

adjacent to the wash rack, any wash water or stormwater that is not captured by wash rack drains

could carry potential releases via the storm drains off-facility to Okatibbee Creek.

3.3 Adjacent Sources

One off-facility, potential source, which is not associated with ARNG activities, was identified 

adjacent to AASF #3 during the PA. The adjacent potential source is shown on Figure 3-1 and 

described in the following sections for informational purposes only, and will not be investigated as 

part of this SI.

3.3.1 Key Field

An SI was performed at Key Field, the adjacent ANG Base, located south and side-gradient of 

AASF #3. A total of six potential release locations were evaluated; PFOA, PFOS, PFBS, PFHxS, 

and PFNA were detected in soil, groundwater, and surface water. The maximum concentrations 

reported in the sampled environmental media are summarized below:

• In soil, maximum concentrations of PFOA, PFOS, PFBS, PFHxS, and PFNA were 

reported at 6.4 micrograms per kilogram ( g/kg), 350 J g/kg, 0.66 g/kg, 34 J g/kg, and 

5.7 μg/kg, respectively.
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Army Aviation Support Facility #3, Meridian, Mississippi

AECOM 3-2

• In groundwater, the maximum concentrations of PFOA, PFOS, PFBS, PFHxS, and PFNA 

in groundwater were reported at 4,100 J nanograms per liter (ng/L), 67,000 J ng/L, 3,700 

ng/L, 34,000 J ng/L, and 280 J ng/L, respectively. 

• In surface water, the maximum concentrations of PFOA, PFOS, PFBS, PFHxS, and PFNA 

were reported at 340 ng/L, 2,200 J ng/L, 270 ng/L, 1,900 J ng/L, and 26 ng/L, respectively.
­ Figure 3-1

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection at Meridian AASF, MS

2/9/2023

2/9/2023

2/9/2023

MS

LC

CM

GIS BY

CHK BY

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Base Map: National Agricultural Imagery Program, 2017. Sources: Esri, HERE, Garmin,

USGS, Intermap, INCREMENT P, NRCan, Esri Japan, METI, Esri China (Hong Kong),

2/9/2023

1:3,600

Area of Interest

12420 Milestone Center Drive

Germantown, MD 20876

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AECOM 3-3
Site Inspection Report

Army Aviation Support Facility #3, Meridian, Mississippi

AECOM 3-4

THIS PAGE INTENTIONALLY BLANK
Site Inspection Report

Army Aviation Support Facility #3, Meridian, Mississippi

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, 2022a), 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 AASF #3 (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, 2022a); 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). The SI scope was bounded vertically by the observed depths of the surficial groundwater 

table. Temporal boundaries of the study were limited by seasonal conditions present during the Spring 

2022 field work.

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, 2022a).

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
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Army Aviation Support Facility #3, Meridian, Mississippi

AECOM 4-2

whether the collected data are of the right type, quality, and quantity to support the decisionmaking (DoD, 2019a; DoD, 2019b; USEPA, 2017).

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

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

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

requirements of the SI QAPP Addendum (AECOM, 2022a).
Site Inspection Report

Army Aviation Support Facility #3, Meridian, Mississippi

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, Army Aviation Support Facility, Meridian dated

September 2020 (AECOM, 2020);

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

Army Aviation Support Facility, Meridian, Mississippi dated March 2022 (AECOM, 2022a);

and

• Final Site Safety and Health Plan, Army Aviation Support Facility, Meridian, Mississippi

dated April 2022 (AECOM, 2022b).

The SI field activities were conducted from 18 to 20 April 2022 and consisted of utility clearance,

direct push boring, soil sample collection, temporary monitoring well installation, grab groundwater

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

QAPP Addendum (AECOM, 2022a), except as previously noted in Section 5.8.

The following samples were collected during the SI and analyzed 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:

• Eighteen (18) soil samples from 10 borings; 

• Six grab groundwater samples from six temporary wells; and

• Fourteen (14) 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, a Field Change Request form is 

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

collection plan. The process encourages stakeholder involvement in the SI, beginning with
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Army Aviation Support Facility #3, Meridian, Mississippi

AECOM 5-2

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 10 March 2022, prior to SI field activities. The

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

stakeholders for this SI include the ARNG, USACE, MSARNG, Mississippi Department of

Environmental Quality, and representatives familiar with the facility, the regulations, and the

community. Stakeholders were provided the opportunity to make comments on the technical

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

combined TPP Meeting 1 and 2 was memorialized in the SI QAPP Addendum (AECOM, 2022a).

A TPP Meeting 3 will be held (date to be determined) after the field event 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 submitted a locate ticket with the Mississippi 811 utility clearance provider to notify them

of intrusive work prior to field activities. Additionally, AECOM contracted Ground Penetrating

Radar Systems, LLC (GPRS), a private utility location service, to perform utility clearance. GPRS

performed utility clearance of the proposed boring locations on 18 April 2022 with input from the

AECOM field team and AASF #3 facility staff. General locating services and ground-penetrating

radar were used to complete the clearance. Additionally, the first 5 feet of each boring were precleared 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

Two potable water sources at AASF #3 were sampled on 23 February 2022 to assess usability

for decontamination of drilling equipment (MER-DECON-01 and MER-DECON-02). Results of the

sample collected at the northwestern spigot (MER-DECON-01) 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 samples 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, 2022a). 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 areas to avoid disturbing concrete or asphalt surfaces. Soil

samples were collected via direct push technology (DPT), in accordance with the SI QAPP

Addendum (AECOM, 2022a). A GeoProbe® 7730DT macrocore 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. Four soil boring 

locations, AOI01-03, AOI01-04, AOI02-03, and AOI02-04, were advanced only using a hand 

auger. Borings AOI01-03 and AOI01-04 were intended to be advanced only using a hand auger

per the SI QAPP Addendum. Borings AOI02-03 and AOI02-04 were originally intended to be 
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Army Aviation Support Facility #3, Meridian, Mississippi

AECOM 5-3

converted into temporary wells once the target depth was reached; however, hand auger refusal 

was encountered at 4 feet bgs. Two additional offset locations were attempted at both locations 

in accordance with the SI QAPP Addendum, but refusal was encountered during each attempted 

offset. The soil boring locations are shown on Figure 5-1, and depths are provided Table 5-1.

Due to shallow groundwater encountered throughout the facility, two 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) and one subsurface soil sample approximately 2 feet above the

groundwater table. This field change is further discussed in Section 5.8.

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 were completed to depths between 4 to 15 feet bgs. Fine-grained clayey sand and 

silty soils were observed as the dominant lithology of the unconsolidated sediments below AASF 

#3. The clayey sands were noted from surface elevations up to 13 feet bgs. Where identified, the 

silts were observed as shallow as 5 feet bgs to as deep as 15 feet bgs. Varying quantities of fineto medium-grained sand were observed in all borings at nearly all depths. Lean clay was observed 

at AOI02-05 (8.5 to 10 feet bgs) near the southern boundary of the facility and MER-01 (3 to 8 

feet bgs) along the northern boundary. Poorly graded sand soils were observed at the bottom of 

borings AOI01-02 (13 to 15 feet bgs) and AOI02-02 (8 to 10 feet bgs), located along the southern 

boundary of the facility. The sandy and clayey soils observed within the borings are consistent 

with the nonmarine sediments of the Hatchetigbee Formation.

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 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) and pH (USEPA Method 9045D) in accordance with the SI QAPP

Addendum (AECOM, 2022a).

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 (°C) during shipment.

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

accordance with the SI QAPP Addendum (AECOM, 2022a) using bentonite chips at completion

of sampling activities. Borings were installed in grass areas to avoid disturbing concrete or asphalt

surfaces.

5.3 Temporary Well Installation and Groundwater Grab Sampling

Temporary wells were installed using a GeoProbe® 7730 macrocore sampling system. Once the

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

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

surface. New PVC pipe and screen were used to avoid cross contamination between locations.
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Army Aviation Support Facility #3, Meridian, Mississippi

AECOM 5-4

Temporary wells could not be installed at two boring locations, AOI02-02 and AOI02-04, due to 

an unknown, plastic-like object encountered at 4 feet bgs. Two additional offset locations were 

attempted at both locations in accordance with the SI QAPP Addendum, but refusal was 

encountered during each attempted offset. The screen intervals for the temporary wells are

provided in Table 5-2.

Groundwater samples were collected after a period of time following well installation to allow

groundwater to infiltrate and recharge the temporary well screen intervals. After the recharge

period, groundwater samples were collected using a peristaltic pump with PFAS-free HDPE

tubing. The temporary wells were purged at a rate determined in the field to reduce turbidity and

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

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

meter and recorded on the field sampling form (Appendix B2) before each grab sample was

collected. 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 subsamples.

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, 2022a).

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.

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

accordance with the SI QAPP Addendum (AECOM, 2022a) by removing the PVC and backfilling

the hole with bentonite chips. Upon completion of well abandonment, the ground surface at each

location was patched to match existing surrounding conditions.

5.4 Synoptic Water Level Measurements

A synoptic groundwater gauging event was performed on 20 April 2022. Groundwater elevation

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

measurements were taken from the northern side of the well casing. Groundwater depths ranged

between 2.33 to 5.56 feet bgs. 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 Mississippi-licensed land surveyors

following guidelines provided in the SOPs provided in the SI QAPP Addendum (AECOM, 2022a).

Survey data from the newly installed wells on the facility were collected on 20 April 2022 in the

applicable Universal Transverse Mercator zone projection with Mississippi State Plane-East North

American Datum 1983 (NAD83, horizontal) and North American Vertical Datum 1988 (NAVD88,

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
Site Inspection Report

Army Aviation Support Facility #3, Meridian, Mississippi

AECOM 5-5

accordance with the SI QAPP Addendum (AECOM, 2022a) and with the Army Guidance for

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

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

gallon Department of Transportation (DOT)-approved steel drums and left onsite in a designated

waste storage area immediately south of AOI 2. The soil IDW was not sampled and assumes the

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

soil IDW will be managed and disposed of by ARNG (either by offsite disposal or onsite disposal 

with treatment, as appropriate) under a separate contract. ARNG will further manage soil IDW in 

accordance with the Army Guidance for Addressing Releases of PFAS, Q18 (DA, 2018). ARNG 

will coordinate transportation and disposal of the soil IDW. 

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

decontamination fluids) were containerized in labeled, 55-gallon DOT-approved steel drums, and

left onsite next to the soil IDW. The liquid IDW was not sampled and assumes the characteristics

of the associated groundwater samples collected from that source location. Containerized liquid

IDW will be managed and disposed of by ARNG (either by offsite disposal or onsite disposal with

treatment, as appropriate) under a separate contract in accordance with SOP No. 042A (EA

Engineering, Science, and Technology, Inc., 2021). ARNG will further manage liquid IDW in

accordance with the Army Guidance for Addressing Releases of PFAS, Q18 (DA, 2018). ARNG

will coordinate transportation and disposal of the liquid IDW.

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 the SI QAPP Addendum

One deviation from the SI QAPP Addendum was identified during review of the field documentation. 

The deviation is noted below and is documented in Field Change Request Forms (Appendix B3).

• According to the SI QAPP Addendum, three soil samples were planned to be collected from 

each soil boring that was converted to a temporary well. All samples were supposed to target 

the soil above the water table in the vadose zone. However, due to shallow groundwater 

encountered at the facility (less than 6 feet bgs), only two samples could be collected. 
Site Inspection Report

Army Aviation Support Facility #3, Meridian, Mississippi 

AECOM 5-6

THIS PAGE INTENTIONALLY BLANK
Table 5-1

Site Inspection Samples by Medium

Site Inspection Report, AASF #3, Meridian, Mississippi

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)

Comments

AOI01-01-SB-00-02 4/19/2022 8:55 0 - 2 x

AOI01-01-SB-03-05 4/19/2022 9:00 3 - 5 x

AOI01-01-SB-03-05-D 4/19/2022 9:00 3 - 5 x Duplicate

AOI01-02-SB-00-02 4/19/2022 9:10 0 - 2 x

AOI01-02-SB-03-05 4/19/2022 9:20 3 - 5 x x x

AOI01-02-SB-03-05-MS 4/19/2022 9:20 3 - 5 x x MS

AOI01-02-SB-03-05-MSD 4/19/2022 9:20 3 - 5 x x MSD

AOI01-03-SB-00-02 4/18/2022 13:45 0 - 2 x

AOI01-03-SB-00-02-MS 4/18/2022 13:45 0 - 2 x MS

AOI01-03-SB-00-02-MSD 4/18/2022 13:45 0 - 2 x MSD

AOI01-04-SB-00-02 4/18/2022 14:05 0 - 2 x

AOI02-01-SB-00-02 4/18/2022 13:00 0 - 2 x

AOI02-01-SB-03-05 4/18/2022 13:05 3 - 5 x

AOI02-02-SB-00-02 4/18/2022 14:40 0 - 2 x

AOI02-02-SB-03-05 4/18/2022 14:45 3 - 5 x

AOI02-03-SB-00-02 4/19/2022 8:30 0 - 2 x

AOI02-03-SB-02-04 4/19/2022 8:35 2 - 4 x

AOI02-04-SB-00-02 4/18/2022 16:00 0 - 2 x x x

AOI02-04-SB-00-02-D 4/18/2022 16:00 0 - 2 x x Duplicate

AOI02-04-SB-02-04 4/18/2022 16:00 2 - 4 x

AOI02-05-SB-00-02 4/18/2022 13:45 0 - 2 x

AOI02-05-SB-00-02-D 4/18/2022 13:45 0 - 2 x Duplicate

AOI02-05-SB-03-05 4/18/2022 13:50 3 - 5 x

MER-01-SB-00-02 4/18/2022 10:40 0 - 2 x

MER-01-SB-03-05 4/18/2022 12:10 3 - 5 x

Soil Samples

AECOM 5-7
Table 5-1

Site Inspection Samples by Medium

Site Inspection Report, AASF #3, Meridian, Mississippi

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)

Comments

AOI01-01-GW 4/20/2022 8:30 NA x

AOI01-02-GW 4/20/2022 9:25 NA x

AOI02-01-GW 4/19/2022 15:45 NA x

AOI02-01-GW-D 4/19/2022 15:45 NA x Duplicate

AOI02-01-GW-MS 4/19/2022 15:45 NA x MS

AOI02-01-GW-MSD 4/19/2022 15:45 NA x MSD

AOI02-02-GW 4/19/2022 17:25 NA x

AOI02-05-GW 4/19/2022 16:40 NA x

MER-01-GW 4/19/2022 8:30 NA x

MER-FRB-01 4/18/2022 14:45 NA x FRB

MER-ERB-01 4/18/2022 11:20 NA x Drill rig shoe

MER-ERB-02 4/20/2022 8:20 NA x Driller hand auger

MER-ERB-03 4/20/2022 8:25 NA x AECOM hand auger

MER-DECON-01 2/23/2022 8:08 NA x Northwestern spigot

MER-DECON-02 2/23/2022 8:15 NA x Northeastern spigot

MER-DECON-03 4/19/2022 11:40 NA x Rig tank

Notes:

ASTM = American Society for Testing and Materials

bgs = below ground surface

ERB = equipment rinsate blank

FRB = field reagent blank

LC/MS/MS = Liquid Chromatography Mass Spectrometry

MS/MSD = matrix spike/ matrix spike duplicate

QSM = Quality Systems Manual

TOC = total organic carbon

USEPA = United States Environmental Protection Agency

Quality Control Samples

Groundwater Samples

AECOM 5-8
Table 5-2

Soil Boring Depths, Temporary Well Screen Intervals, and Groundwater Elevations

Site Inspection Report, AASF #3, Meridian, Mississippi

Area of 

Interest

Boring 

Location

Soil Boring 

Depth 

(feet bgs)

Temporary Well 

Screen Interval 

(feet bgs)

Top of Casing 

Elevation 

(feet NAVD88)

Ground Surface 

Elevation 

(feet NAVD88)

Depth to 

Water

(feet btoc)

Depth to 

Water

(feet bgs)

Groundwater 

Elevation

(feet NAVD88)

AOI01-01 15 8-13 307.38 303.54 7.60 3.76 299.78

AOI01-021 15 9-14 304.37 303.65 6.28 5.56 298.09

AOI02-01 15 10-15 303.00 301.86 5.89 4.75 297.11

AOI02-02 10 5-10 300.69 300.14 3.61 3.06 297.08

AOI02-032 4 N/A N/A N/A N/A N/A N/A

AOI02-042 4 N/A N/A N/A N/A N/A N/A

AOI02-05 10 5-10 301.52 300.51 4.58 3.57 296.94

Facilitywide MER-01 10 5-10 303.28 301.62 3.99 2.33 299.29

Notes:

1. Depth to water was measured immediately prior to sampling. Sampling occurred within 16 hours of the synoptic gauging measurement (9.62 feet btoc).

2. No temporary well was installed due to early refusal.

bgs = below ground surface

btoc = below top of casing

NAVD88 = North American Vertical Datum 1988

1

2

AECOM 5-9
Site Inspection Report

Army Aviation Support Facility #3, Meridian, Mississippi 

AECOM 5-10

THIS PAGE INTENTIONALLY BLANK
­ CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

CD

11/8/2022

11/8/2022

Site Inspection at Meridian AASF, MS

11/8/2022

Figure 5-1 PM CM 11/8/2022

12420 Milestone Center Drive

Germantown, MD 20876

Site Inspection Sample Locations

Base Map: National Agricultural Imagery Program, 2017.

Sources: Esri, HERE, Garmin, USGS, Intermap,

PROJECT

?!

?!

"S ?!

"S

?!

?! ?!

?!

?!

AOI 1

AOI 2

MER-01

AOI01-01

AOI01-03 AOI01-02

AOI01-04

AOI02-01

AOI02-02 AOI02-03

AOI02-04

AOI02-05

0 60 120 240

Feet

Legend

?! Soil Boring/Temporary Well

?! Soil Boring

"S Surface Soil Sample

Area of Interest

Facility Boundary

Groundwater Flow Direction

AECOM 5-11
Site Inspection Report

Army Aviation Support Facility #3, Meridian, Mississippi 

AECOM 5-12

THIS PAGE INTENTIONALLY BLANK
Site Inspection Report

Army Aviation Support Facility #3, Meridian, Mississippi 

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 6.4. Table 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, theAOI 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 to 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

Army Aviation Support Facility #3, Meridian, Mississippi 

AECOM 6-2

6.2 Soil Physicochemical Analyses

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

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

results of the TOC and pH sampling. 

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

appropriate, to assess fate and transport. 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: Release Area A. 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 

Figure 6-1 through Figure 6-5 present the ranges of detections in soil. Table 6-2 through Table

6-3 summarize the soil results.

Surface soil was sampled from 0 to 2 feet bgs from boring locations AOI01-01 through AOI01-04. 

Soil was also sampled from shallow subsurface soil (3 to 5 feet bgs) from boring locations AOI01-

01 and AOI01-02. Deep subsurface soil was not collected due to shallow groundwater. PFOA,

PFOS, PFBS, PFHxS, and PFNA and were detected in soil, at concentrations below their SLs in 

the surface and shallow subsurface soil. 

In surface soil, PFOA, PFOS, PFHxS, and PFNA were detected at all four locations, and PFBS 

was detected at one of four locations. The constituents were all detected at concentrations below 

their SLs. The maximum detected concentration was for PFNA, detected at 14.9 μg/kg at AOI01-

04, below the SL of 19 μg/kg. 

In shallow subsurface soil, PFOA, PFOS, PFHxS, and PFNA were detected at both locations, and 

PFBS was only detected at AOI01-02. The relevant compounds were all detected at 

concentrations at least one order of magnitude below the SLs. The maximum concentration 

detected was PFNA at 12.9 J μg/kg at AOI01-01.

6.3.2 AOI 1 Groundwater Analytical Results 

Groundwater was sampled from temporary monitoring wells AOI01-01 and AOI01-02. Figure 6-6

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

groundwater results. The following exceedances of the SLs were measured:

• PFOA was detected above the SL of 6 ng/L, with concentrations of 3,160 ng/L at AOI01-

01 and 45.5 ng/L at AOI01-02.

• PFOS was detected above the SL of 4 ng/L, with concentrations of 391 ng/L at AOI01-01

and 15.7 ng/L at AOI01-02.
Site Inspection Report

Army Aviation Support Facility #3, Meridian, Mississippi 

AECOM 6-3

• PFHxS was detected above the SL of 39 ng/L, with concentrations of 473 ng/L at AOI01-01

and 47.4 ng/L at AOI01-02.

• PFNA was detected above the SL of 6 ng/L, with a concentration of 988 ng/L at AOI01-01.

PFBS did not exceed the SL of 601 ng/L at either temporary well. The maximum detected

concentration of PFBS was 61.7 ng/L at AOI01-01. 

6.3.3 AOI 1 Conclusions

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

below their SLs. PFOA, PFOS, PFHxS, and PFNA were detected in groundwater at

concentrations above their SLs. 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: Release Area B. 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 

Figure 6-1 through Figure 6-5 present the ranges of detections in soil. Table 6-2 through Table

6-3 summarize the soil results.

Surface soil was sampled from 0 to 2 feet bgs from boring locations AOI02-01 through AOI02-05, 

as well as the side-gradient boring location MER-01. Soil was also sampled from shallow 

subsurface soil (2 to 5 feet bgs) from boring locations AOI02-01 through AOI02-05 and sidegradient boring location MER-01. Deep subsurface soil was not collected. PFOA, PFOS, PFBS, 

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

shallow subsurface soil.

In surface soil, PFOA and PFOS were detected at all six locations, PFHxS and PFNA were 

detected in five of six surface samples, and PFBS was detected at one of six locations. The 

relevant compounds were all detected below their SLs. The maximum concentration detected 

was PFOS, which was detected at 2.67 μg/kg at AOI02-04, below the 13 μg/kg SL. 

In shallow subsurface soil, PFOS and PFHxS were detected at all six locations, PFOA was 

detected at three of six locations, and PFNA was detected at two of six locations; PFBS was not 

detected. The relevant compounds were all detected at least two orders of magnitude below the 

SLs. The maximum concentration detected was PFOS at 0.669 J μg/kg at AOI02-03. 

6.4.2 AOI 2 Groundwater Analytical Results 

Groundwater at AOI 2 was sampled from temporary monitoring wells AOI02-01, AOI02-02, and 

AOI02-05. Groundwater was also sampled from the side-gradient temporary well MER-01. Figure 

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

groundwater results. The following exceedances of the SLs were measured:

• PFOA was detected above the SL of 6 ng/L at all three temporary wells, with

concentrations ranging from 6.38 ng/L at AOI02-02 to 69.0 ng/L at AOI02-05. PFOA was

also detected above the SL at MER-01, with a concentration of 17.8 ng/L.
Site Inspection Report

Army Aviation Support Facility #3, Meridian, Mississippi

AECOM 6-4

• PFOS was detected above the SL of 4 ng/L at all three temporary wells, with 

concentrations ranging from 4.94 ng/L at AOI02-02 to 594 at AOI02-05. PFOS was also 

detected above the SL at MER-01, with a concentration of 13.0 ng/L. 

• PFHxS was detected above the SL of 39 ng/L at all three temporary wells, with 

concentrations ranging from 84.3 J- ng/L at AOI02-01 to 497 ng/L at AOI02-02. PFHxS 

was also detected above the SL at MER-01, with a concentration of 70.8 ng/L.

• PFNA was detected above the SL of 6 ng/L at one temporary well (AOI02-05), with a 

concentration of 18.8 ng/L.

PFBS did not exceed the SL of 601 ng/L at any of the temporary wells. The maximum detected 

concentration of PFBS was 43.6 ng/L at AOI02-02. 

6.4.3 AOI 2 Conclusions

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

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

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

further evaluation at AOI 2 is warranted. 
Table 6-2

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

Site Inspection Report, Meridian AASF

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual

PFBS 1900 ND U 0.372 J ND U ND U ND U ND U ND U 0.022 J ND U ND U

PFHxS 130 0.045 J 2.10 0.043 J 0.087 J 0.072 J ND U 0.438 J 0.685 J 0.102 J 0.142 J

PFNA 19 4.54 0.160 J 12.2 J 14.9 0.308 J 0.042 J 0.046 J 0.036 J 0.611 J 0.839 J

PFOA 19 2.95 1.26 4.78 J- 3.96 0.301 J 0.103 J 0.604 J 0.244 J 0.596 J 0.740 J

PFOS 13 0.435 J 2.30 0.554 J 1.35 1.54 0.287 J 0.821 J 2.67 1.71 2.64

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AASF Army Aviation Support Facility

J- = Estimated concentration, biased low 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 limit

Notes ft feet

ND = Analyte not detected above the LOD. LOD values are presented in Appendix F. HQ hazard quotient

ID identification

LCMSMS liquid chromatography with tandem mass spectrometry

Limit of Detection (LOD) ranges for relevant compounds: LOD limit of detection

PFBS: 0.051-0.063 μg/kg MER Meridian

PFHxS: 0.102-0.127 μg/kg ND analyte not detected above the LOD

PFNA: 0.051-0.063 μg/kg OSD Office of the Secretary of Defense

PFOA: 0.204-0.253 μg/kg QSM Quality Systems Manual

PFOS: 0.204-0.253 μg/kg Qual interpreted qualifier

SB soil boring

USEPA United States Environmental Protection Agency

μg/kg micrograms per kilogram

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 incidental ingestion of contaminated soil.

AOI02-05-SB-00-02-D

04/18/2022

0-2 ft

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

AOI02-04-SB-00-02

04/18/2022

0-2 ft

AOI02-05-SB-00-02

04/18/2022

0-2 ft

AOI02-02-SB-00-02

0-2 ft

AOI02-01-SB-00-02

04/18/2022

0-2 ft

AOI02

04/18/2022

0-2 ft

AOI02-03-SB-00-02

04/19/2022

0-2 ft

Area of Interest

Sample ID

Sample Date

Depth

AOI01-01-SB-00-02

04/19/2022

0-2 ft

AOI01

AOI01-02-SB-00-02

04/19/2022

0-2 ft

AOI01-03-SB-00-02

04/18/2022

0-2 ft

AOI01-04-SB-00-02

04/18/2022

AECOM 6-5
Table 6-2

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

Site Inspection Report, Meridian AASF

Analyte OSD Screening 

Level a

Result Qual

PFBS 1900 ND U

PFHxS 130 0.187 J

PFNA 19 ND U

PFOA 19 0.148 J

PFOS 13 0.291 J

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AASF Army Aviation Support Facility

J- = Estimated concentration, biased low 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 limit

Notes ft feet

ND = Analyte not detected above the LOD. LOD values are presented in Appendix F. HQ hazard quotient

ID identification

LCMSMS liquid chromatography with tandem mass spectrometry

Limit of Detection (LOD) ranges for relevant compounds: LOD limit of detection

PFBS: 0.051-0.063 μg/kg MER Meridian

PFHxS: 0.102-0.127 μg/kg ND analyte not detected above the LOD

PFNA: 0.051-0.063 μg/kg OSD Office of the Secretary of Defense

PFOA: 0.204-0.253 μg/kg QSM Quality Systems Manual

PFOS: 0.204-0.253 μg/kg Qual interpreted qualifier

SB soil boring

USEPA United States Environmental Protection Agency

μg/kg micrograms per kilogram

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

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 incidental ingestion of contaminated soil.

Area of Interest

Sample ID

Sample Date

Depth

Facility-wide

MER-01-SB-00-02

04/18/2022

0-2 ft

AECOM 6-6
Table 6-3

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

Site Inspection Report, Meridian AASF

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual

PFBS 25000 ND U ND U 0.205 J ND U ND U ND U ND U ND U ND U

PFHxS 1600 ND UJ 0.039 J 0.891 J 0.040 J 0.536 J 0.284 J 0.216 J 0.584 J 0.064 J

PFNA 250 1.65 J 12.9 J 0.190 J 0.037 J ND U 0.035 J ND U ND U ND U

PFOA 250 2.33 J 5.14 J 1.36 ND U ND U 0.307 J 0.139 J 0.173 J ND U

PFOS 160 0.375 J 1.06 J 1.57 0.312 J 0.092 J 0.669 J 0.065 J 0.162 J 0.059 J

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AASF Army Aviation Support Facility

U = The analyte was not detected at a level greater than or equal to the adjusted DL AOI Area of Interest

UJ = The analyte was not detected at a level greater than or equal to the adjusted DL. However, the reported adjusted DL is approximate and may be inaccurate or imprecise. D duplicate

DL detection limit

Notes ft feet

ND = Analyte not detected above the LOD. LOD values are presented in Appendix F. HQ hazard quotient

ID identification

LCMSMS liquid chromatography with tandem mass spectrometry

Limit of Detection (LOD) ranges for relevant compounds: LOD limit of detection

PFBS: 0.053-0.058 μg/kg MER Meridian

PFHxS: 0.105-0.117 μg/kg ND analyte not detected above the LOD

PFNA: 0.053-0.058 μg/kg OSD Office of the Secretary of Defense

PFOA: 0.211-0.233 μg/kg QSM Quality Systems Manual

PFOS: 0.211-0.233 μg/kg Qual interpreted qualifier

SB soil boring

USEPA United States Environmental Protection Agency

μg/kg micrograms per kilogram

Area of Interest

Sample ID

Sample Date

Depth

AOI01-01-SB-03-05

04/19/2022

3-5 ft

AOI01-01-SB-03-05-D

04/19/2022

3-5 ft

AOI01-02-SB-03-05

04/19/2022

3-5 ft 2-4 ft

AOI02-01-SB-03-05

04/18/2022

3-5 ft

AOI02-02-SB-03-05

04/18/2022

3-5 ft

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

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.

AOI01 AOI02

AOI02-05-SB-03-05

04/18/2022

3-5 ft

Facility-wide

MER-01-SB-03-05

04/18/2022

3-5 ft

AOI02-03-SB-02-04

04/19/2022

2-4 ft

AOI02-04-SB-02-04

04/18/2022

AECOM 6-7
Table 6-4

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

Site Inspection Report, Meridian AASF

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual

PFBS 601 61.7 6.84 8.34 7.53 43.6 9.57 3.13 J

PFHxS 39 473 47.4 92.8 J- 84.3 J- 497 397 70.8

PFNA 6 988 5.79 2.65 J 2.30 J ND U 18.8 ND U

PFOA 6 3160 45.5 23.0 20.9 6.38 69.0 17.8

PFOS 4 391 15.7 52.4 45.8 4.94 594 13.0

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AASF Army Aviation Support Facility

J- = Estimated concentration, biased low 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 limit

Notes GW groundwater

ND = Analyte not detected above the LOD. LOD values are presented in Appendix F. HQ hazard quotient

ID identification

LCMSMS liquid chromatography with tandem mass spectrometry

Limit of Detection (LOD) ranges for relevant compounds: LOD limit of detection

PFBS: 1.85-8.93 ng/L MER Meridian

PFHxS: 2.78-13.4 ng/L ND analyte not detected above the LOD

PFNA: 1.85-8.93 ng/L OSD Office of the Secretary of Defense

PFOA: 1.85-8.93 ng/L QSM Quality Systems Manual

PFOS: 1.85-8.93 ng/L Qual interpreted qualifier

USEPA United States Environmental Protection Agency

ng/l nanogram per liter

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.

AOI01 AOI02

AOI02-05-GW

04/19/2022

Facility-wide

MER-01-GW

04/19/2022

AOI02-01-GW-D

04/19/2022

AOI02-02-GW

04/19/2022

AOI01-02-GW

04/20/2022

AOI02-01-GW

04/19/2022

Area of Interest

Sample ID

Sample Date

AOI01-01-GW

04/20/2022

AECOM 6-8
MER-01

AOI01-01

AOI01-03 AOI01-02

AOI01-04

AOI02-01

AOI02-02 AOI02-03

AOI02-04

AOI02-05

0 45 90 180

Feet

Legend

Facility Boundary

MER-01

AOI01-01

AOI01-02

AOI02-01

AOI02-02 AOI02-03

AOI02-04

AOI02-05

­ Figure 6-1

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection at Meridian AASF, MS

9/19/2022

9/19/2022

9/19/2022

MS

CD

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, USGS, Intermap, INCREMENT P, NRCan,

Esri Japan, METI, Esri China (Hong Kong), Esri Korea, Esri (Thailand), NGCC, (c)

9/19/2022

1:1,080

PFOA Detections in Soil

12420 Milestone Center Drive

Germantown, MD 20876

Shallow Intermediate

PFOA Results (μg/Kg)

ND

>ND - 19

>19 - 250

>250 - 2,500

>2,500

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

Depth intervals shown represent respective sampling position within a given soil boring location.

AECOM 6-9
MER-01

AOI01-01

AOI01-03 AOI01-02

AOI01-04

AOI02-01

AOI02-02 AOI02-03

AOI02-04

AOI02-05

0 45 90 180

Feet

Legend

Facility Boundary

MER-01

AOI01-01

AOI01-02

AOI02-01

AOI02-02 AOI02-03

AOI02-04

AOI02-05

­ Figure 6-2

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection at Meridian AASF, MS

9/19/2022

9/19/2022

9/19/2022

MS

CD

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, USGS, Intermap, INCREMENT P, NRCan,

Esri Japan, METI, Esri China (Hong Kong), Esri Korea, Esri (Thailand), NGCC, (c)

9/19/2022

1:1,080

PFOS Detections in Soil

12420 Milestone Center Drive

Germantown, MD 20876

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.

PFOS Results (μg/Kg)

ND

>ND - 13

>13 - 160

>160 - 1,600

>1,600

AECOM 6-10
MER-01

AOI01-01

AOI01-03 AOI01-02

AOI01-04

AOI02-01

AOI02-02 AOI02-03

AOI02-04

AOI02-05

0 45 90 180

Feet

Legend

Facility Boundary

MER-01

AOI01-01

AOI01-02

AOI02-01

AOI02-02 AOI02-03

AOI02-04

AOI02-05

­ Figure 6-3

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection at Meridian AASF, MS

9/19/2022

9/19/2022

9/19/2022

MS

CD

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, USGS, Intermap, INCREMENT P, NRCan,

Esri Japan, METI, Esri China (Hong Kong), Esri Korea, Esri (Thailand), NGCC, (c)

9/19/2022

1:1,080

PFBS Detections in Soil

12420 Milestone Center Drive

Germantown, MD 20876

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.

PFBS Results (μg/Kg)

ND

>ND - 10

>10 - 1,900

>1,900 - 25,000

>25,000

AECOM 6-11
MER-01

AOI01-01

AOI01-03 AOI01-02

AOI01-04

AOI02-01

AOI02-02 AOI02-03

AOI02-04

AOI02-05

0 45 90 180

Feet

Legend

Facility Boundary

MER-01

AOI01-01

AOI01-02

AOI02-01

AOI02-02 AOI02-03

AOI02-04

AOI02-05

­ Figure 6-4

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection at Meridian AASF, MS

9/19/2022

9/19/2022

9/19/2022

MS

CD

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, USGS, Intermap, INCREMENT P, NRCan,

Esri Japan, METI, Esri China (Hong Kong), Esri Korea, Esri (Thailand), NGCC, (c)

9/19/2022

1:1,080

PFHxS Detections in Soil

12420 Milestone Center Drive

Germantown, MD 20876

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.

PFHxS Results (μg/Kg)

ND

>ND - 10

>10 - 130

>130 - 1,600

>1,600

AECOM 6-12
MER-01

AOI01-01

AOI01-03 AOI01-02

AOI01-04

AOI02-01

AOI02-02 AOI02-03

AOI02-04

AOI02-05

0 45 90 180

Feet

Legend

Facility Boundary

MER-01

AOI01-01

AOI01-02

AOI02-01

AOI02-02 AOI02-03

AOI02-04

AOI02-05

­ Figure 6-5

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection at Meridian AASF, MS

9/19/2022

9/19/2022

9/19/2022

MS

CD

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, USGS, Intermap, INCREMENT P, NRCan,

Esri Japan, METI, Esri China (Hong Kong), Esri Korea, Esri (Thailand), NGCC, (c)

9/19/2022

1:1,080

PFNA Detections in Soil

12420 Milestone Center Drive

Germantown, MD 20876

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.

PFNA Results (μg/Kg)

ND

>ND - 19

>19 - 250

>250 - 2,500

>2,500

AECOM 6-13
MER-01

AOI01-01

AOI01-02

AOI02-01

AOI02-02

AOI02-05

0 80 160 320

Feet

Legend

Facility Boundary

Groundwater Flow Direction

MER-01

AOI01-01

AOI01-02

AOI02-01

AOI02-02

AOI02-05

MER-01

AOI01-01

AOI01-02

AOI02-01

AOI02-02

AOI02-05

­ Figure 6-6

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection at Meridian AASF, MS

10/6/2022

10/6/2022

10/6/2022

MS

CD

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, USGS, Intermap, INCREMENT P, NRCan,

Esri Japan, METI, Esri China (Hong Kong), Esri Korea, Esri (Thailand), NGCC, (c)

10/6/2022

1:1,920

PFOA, PFOS, and PFBS Detections in Groundwater

12420 Milestone Center Drive

Germantown, MD 20876

PFOA PFOS PFBS

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

PFOA Results (ng/L)

ND

>ND - 6

>6 - 40

>40 - 70

>70

PFOS Results (ng/L)

ND

>ND - 4

>4 - 40

>40 - 70

>70

PFBS Results (ng/L)

ND

>ND - 100

>100 - 601

>601 - 2,000

>2,000

AECOM 6-14
MER-01

AOI01-01

AOI01-02

AOI02-01

AOI02-02

AOI02-05

0 50 100 200

Feet

Legend

Groundwater Flow Direction

Facility Boundary

MER-01

AOI01-01

AOI01-02

AOI02-01

AOI02-02

AOI02-05

­ Figure 6-7

CLIENT

REVISED

SCALE

PROJECT

ARNG

Site Inspection at Meridian AASF, MS

9/19/2022

9/19/2022

9/19/2022

MS

CD

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, USGS, Intermap, INCREMENT P, NRCan,

Esri Japan, METI, Esri China (Hong Kong), Esri Korea, Esri (Thailand), NGCC, (c)

9/19/2022

1:1,200

PFHxS and PFNA Detections in Groundwater

12420 Milestone Center Drive

Germantown, MD 20876

PFHxS PFNA

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

PFHxS Results (ng/L)

ND

>ND - 39

>39 - 100

>100 - 1,000

>1,000

PFNA Results (ng/L)

ND

>ND - 6

>6 - 100

>100 - 1,000

>1,000

AECOM 6-15
Site Inspection Report

Army Aviation Support Facility #3, Meridian, Mississippi 

AECOM 6-16

THIS PAGE INTENTIONALLY BLANK
Site Inspection Report

Army Aviation Support Facility #3, Meridian, Mississippi 

AECOM 7-1

7. Exposure Pathways

The CSMs for each AOI, revised based on the SI findings, are presented on Figure 7-1 and

Figure 7-2. Please note that while the CSM discussion assists in determining if a receptor may

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

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

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

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

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

potentially complete when the following conditions are present:

1. Contaminant source;

2. Environmental fate and transport;

3. Exposure point;

4. Exposure route; 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 (although unlikely due to restricted access), residents outside the facility

boundary, and recreational users outside of the facility boundary. No construction was observed 

during SI field activities.

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 and AOI 2 based on the aforementioned

criteria. 

7.1.1 AOI 1 

An AFFF-equipped fire suppression system was installed in the hangar in 2007. The fire 

suppression system includes an outdoor upright 500-gallon tank. The bladder of the tank was

replaced between 2015 to 2016. Evidence of leaked/spilled AFFF was observed on the outside 
Site Inspection Report

Army Aviation Support Facility #3, Meridian, Mississippi 

AECOM 7-2

of the tank during the visual site inspection. Spills from the tank would have resulted in impacts 

to the surface soil.

PFOA, PFOS, PFBS, PFHxS, and PFNA were detected in surface soil at AOI 1. Site workers, 

future construction workers, and trespassers could contact constituents in surface soil via

incidental ingestion and inhalation of dust. Therefore, the surface soil exposure pathways for

these receptors are potentially complete. PFOA, PFOS, PFBS, PFHxS, and PFNA were detected

in shallow subsurface soil at AOI 1. Future construction workers could contact constituents in

shallow subsurface soil via incidental ingestion, and therefore, the subsurface soil exposure

pathway for future construction workers is potentially complete. The pathways for offsite residents 

and recreational users are incomplete. The CSM for AOI 1 is presented on Figure 7-1. 

7.1.2 AOI 2 

Approximately 10 Tri-MaxTM carts were positioned at the wash rack area between 2007 to 

2011/2012. A contractor for the State of Mississippi emptied the units prior to removing them from 

the facility. It is unknown if the AFFF were discharged down the wash rack or in the nearby, 

adjacent grassy areas. The wash rack conveys water to the OWS then to the sanitary sewer.

PFOA, PFOS, PFBS, PFHxS, and PFNA were detected in surface soil at AOI 2. Site workers, 

future construction workers, and trespassers could contact constituents in surface soil via 

incidental ingestion and inhalation of dust. Therefore, the surface soil exposure pathways for 

these receptors are potentially complete. PFOA, PFOS, PFHxS, and PFNA were detected in 

shallow subsurface soil at AOI 2. Future construction workers could contact constituents in 

shallow subsurface soil via incidental ingestion; therefore, the subsurface soil exposure pathway 

for future construction workers is potentially complete. The pathways for offsite residents and 

recreational users are incomplete. The CSM for AOI 2 is presented on Figure 7-2. 

7.2 Groundwater Exposure Pathway

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

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

7.2.1 AOI 1 

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

samples collected at AOI 1. Domestic wells and wells of unknown use are located within a 4-mile 

radius of the facility. These wells are screened in the unconfined Wilcox Group, at least 135 feet 

bgs; therefore, the pathway for exposure to off-facility residents via ingestion of groundwater is 

considered potentially complete. Additionally, drinking water at the facility is supplied by the City 

of Meridian and is sourced from eight potable wells pumping from the Lower Wilcox aquifer. 

Therefore, the pathway for exposure to site workers via ingestion of groundwater is considered 

potentially complete. Depths to water measured at AOI 1 in April 2022 during the SI ranged from

3.76 to 5.56 feet bgs. The construction worker exposure scenario assumes excavation occurs at 

depths at or above 15 feet bgs. Therefore, the ingestion exposure pathway for future construction

workers is considered potentially complete with exceedance of SL. Additionally, during wet 

periods, the water level may rise to depths shallower than 2 feet bgs. Therefore, the incidental 

ingestion pathway for future site workers is considered potentially complete when the groundwater 

is shallower than 2 feet bgs. The incidental exposure pathway to recreational users is incomplete.

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

Army Aviation Support Facility #3, Meridian, Mississippi 

AECOM 7-3

7.2.2 AOI 2 

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

samples collected at AOI 2. Domestic wells and wells of unknown use that are screened within 

the unconfined Wilcox Group are located within a 4-mile radius of the facility. Therefore, the 

pathway for exposure to off-facility residents via ingestion of groundwater is considered potentially 

complete. Additionally, facility drinking water is sourced from the Lower Wilcox aquifer; 

consequently, the pathway for exposure to site workers via ingestion of groundwater is considered 

potentially complete. Depths to water measured at AOI 2 in April 2022 during the SI ranged from 

3.06 to 4.75 feet bgs. The construction worker exposure scenario assumes excavation occurs at 

depths at or above 15 feet bgs. Therefore, the ingestion exposure pathway for future construction 

workers is considered potentially complete with exceedance of SL. Additionally, during wet 

periods, the water level may rise to depths shallower than 2 feet bgs. Therefore, the incidental 

ingestion pathway for future site workers is considered potentially complete when the groundwater 

is shallower than 2 feet bgs. The incidental exposure pathway to recreational users is incomplete. 

The CSM for AOI 2 is presented on Figure 7-2. 

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.

7.3.1 AOI 1 

PFAS are water soluble and can migrate readily from soil to surface water via leaching and runoff. PFOA, PFOS, PFBS, PFHxS, and PFNA were detected in soil and shallow groundwater at

AOI 1; therefore, it is possible that those compounds may have migrated from soil and

groundwater to the stormwater management area, wetlands, and/or Okatibbee Creek via shallow 

groundwater discharge, storm water flow, and overland flow. Chickasawhay River, an outfall of 

the Okatibbee Creek, adjoins numerous residences and is used recreationally. Therefore, the 

surface water and sediment ingestion exposure pathways for site workers, future construction 

workers, and recreational users are considered potentially complete. Drinking water is sourced 

from the Lower Wilcox aquifer; therefore, the residential exposure pathway is incomplete for 

surface water and sediment. The CSM for AOI 1 is presented on Figure 7-1. 

7.3.2 AOI 2 

PFOA, PFOS, PFBS, PFHxS, and PFNA were detected in soil and shallow groundwater at AOI 

2, and it is possible that those compounds may have migrated from soil and groundwater to the 

stormwater management area, wetlands, and/or Okatibbee Creek via shallow groundwater 

discharge, storm water flow, and overland flow. Chickasawhay River, an outfall of the Okatibbee 

Creek, adjoins numerous residences and is used recreationally. Therefore, the surface water and 

sediment ingestion exposure pathways for site workers, future construction workers, and 

recreational users are considered potentially complete. Drinking water is sourced from the Lower 

Wilcox aquifer; therefore, the residential exposure pathway is incomplete for surface water and 

sediment. The CSM for AOI 2 is presented on Figure 7-2. 
Site Inspection Report

Army Aviation Support Facility #3, Meridian, Mississippi 

AECOM 7-4

THIS PAGE INTENTIONALLY BLANK
Media

SOURCE PATHWAY RECEPTOR

AOI 1

AFFF Fire

Suppression

System

Human

Activities

Precipitation/

Run-Off

Leaching/

Infiltration

Airborne Soil

Particulate

Surface Soil

Surface

Water/

Sediment

Subsurface

Soil

Shallow

Groundwater

Source Release

Mechanism Media Transportand Migration Media ExposureRoutes

Inhalation of

Dust

Ingestion

Ingestion

Ingestion

Ingestion

Human Receptors:

Current/ Future

Flow-Chart Continues

Partial / Possible Flow

Flow-Chart Stops

Incomplete Pathway

Potentially Complete Pathway

Potentially Complete Pathway

with Exceedance of SL

LEGEND

Figure 7-1

Conceptual Site Model, AOI 1

AASF #3, Meridian, Mississippi

Potential

Off-Facility

Source Not

Under

Control of

ARNG

Surface Soil

NOTES

1. No construction activities were observed

during SI field activities.

2. The resident and recreational users refer

to off-site receptors.

/ / / /

Site

Worker

Construction

Worker1

Resident2

Recreational

User/Trespasser2

/ / / /

Site

Worker

Construction

Worker1 Resident2

/ / / /

Recreational

User/Trespasser2

/ / / /

/ / / /

AECOM 7-5
SOURCE PATHWAY

Source Release

Mechanism Media Transportand Migration Media ExposureRoutes

Flow-Chart Continues

Partial / Possible Flow

Flow-Chart Stops

Incomplete Pathway

Potentially Complete Pathway

Potentially Complete Pathway

with Exceedance of SL

LEGEND

Figure 7-2

Conceptual Site Model, AOI 2

AASF #3, Meridian, Mississippi

NOTES

1. No construction activities were observed

during SI field activities.

2. The resident and recreational users refer

to off-site receptors.

RECEPTOR

Human Receptors:

Current/ Future

Recreational

User/Trespasser2

Site

Worker

Construction

Worker1 Resident2

Site

Worker

Construction

Worker1

Resident2 Recreational

User/Trespasser2

AOI 2

Portable

Tri-MaxTM Unit

Storage

Human

Activities

Precipitation/

Run-Off

Leaching/

Infiltration

Surface Soil

Surface

Water/

Sediment

Subsurface

Soil

Shallow

Groundwater

Inhalation of

Dust

Ingestion

Ingestion

Ingestion

Ingestion

Potential

Off-Facility

Source Not

Under

Control of

ARNG

Surface Soil

Airborne Soil

Particulate

/ / / /

/ / / /

/ / / /

/ / / /

/ / / /

AECOM 7-6
Site Inspection Report

Army Aviation Support Facility #3, Meridian, Mississippi

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 18 to 20 April 2022 and consisted of utility clearance,

direct push boring, soil sample collection, temporary monitoring well installation, grab groundwater

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

QAPP Addendum (AECOM, 2022a), except as previously noted in Section 5.8.

To fulfill the project DQOs set forth in the approved SI QAPP Addendum (AECOM, 2022a), 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.

• Eighteen (18) soil samples from 10 borings;

• Six grab groundwater samples from six temporary wells; and

• Fourteen (14) 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 is warranted in an RI for AOI 1 and AOI 2 (see 

Table 8-1). Based on the CSMs developed and revised in light of the SI findings, there is potential

for exposure to residential drinking water receptors from AOI 1 and AOI 2 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:

• The detected concentrations of PFOA, PFOS, PFBS, PFHxS, and PFNA in soil at

AOI 1 were below their SLs.

• PFOA, PFOS, PFHxS, and PFNA in groundwater exceeded their SLs. PFOA and 

PFOS had maximum concentrations of 3,160 ng/L and 391 ng/L, respectively. 

PFHxS and PFNA had maximum concentrations of 473 ng/L and 988 ng/L, 

respectively. The maximum concentrations were all detected at AOI01-01. 

• Based on the exceedances of the groundwater SLs, further evaluation of AOI 1 is 

warranted.
Site Inspection Report

Army Aviation Support Facility #3, Meridian, Mississippi 

AECOM 8-2

• At AOI 2: 

• The detected concentrations of PFOA, PFOS, PFBS, PFHxS, and PFNA in soil at 

AOI 1 were below their SLs. 

• PFOA, PFOS, PFHxS, and PFNA in groundwater exceeded their SLs. PFOA and 

PFOS had maximum concentrations of 69.0 ng/L and 594 ng/L, respectively. PFHxS 

and PFNA had maximum concentrations of 497 ng/L and 18.8 ng/L, respectively. 

• Based on the exceedances of the groundwater SLs, further evaluation of AOI 2 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 Areaa

Groundwater –

Source Areaa

Groundwater –

Facility Boundary

Future 

Action

1 Release Area A

14.9 μg/kg (PFNA) 3,160 ng/L (PFOA) 70.8 ng/L (PFHxS)

Proceed to 

RI 

2 Release Area B

2.67 μg/kg (PFOS) 594 ng/L (PFOS) 70.8 ng/L (PFHxS)

Proceed to 

RI

Notes:

AOI = area of interest; ng/L = nanograms per liter; μg/kg = micrograms per kilogram

a.) The maximum relevant compound concentration is reported at each AOI.

Legend:

 = detected; exceedance of the screening levels

 = detected; no exceedance of the screening levels

 = not detected
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Army Aviation Support Facility #3, Meridian, Mississippi 

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, AASF #3, Meridian, Mississippi. 

September. 

AECOM. 2022a. Final Site Inspection Quality Assurance Project Plan Addendum, Army Aviation 

Support Facility, Meridian, Mississippi, Perfluorooctanesulfonic Acid (PFOS) and 

Perfluorooctanoic Acid (PFOA) Impacted Sites ARNG Installations, Nationwide. Contract No. 

W912DR-12-D-0014/W912DR17F0192. March.

AECOM. 2022b. Final Site Safety and Health Plan, Army Aviation Support Facility, Meridian, 

Mississippi, Perfluorooctane Sulfonic Acid (PFOS) and Perfluorooctanoic Acid (PFOA)

Impacted Sites ARNG Installations, Nationwide. April. 

Allgood, Velton C. 1983. Soil Survey of Lauderdale County, Mississippi. United States Soil 

Conservation Service, Mississippi Agricultural and Forestry Experiment Station.

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

the Department of Defense Cleanup Program. United States Department of Defense. 

6 July. 

Bhate Associates. 2011. Spill Prevention, Control, and Countermeasure Plan and Spill 

Contingency Plan for Mississippi Army National Guard Army Aviation Support Facility #3, 

Meridian, Mississippi. Contract Number: 10-A&E-34-F; Bhate Project Number: 9100134

CH2M Hill. 1992. Final Site Investigation Report, 186th Tactical Reconnaissance Group, Key 

Field, Meridian, Mississippi. July.

City of Meridian. 2021. 2020 Annual Drinking Water Quality Report. Accessed 25 October 2022 

at https://www.meridianms.org/city-departments/finance-and-records/reports/annualdrinking-water-quality-report/2020/. 

DA. 2018. 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.

EDRTM. 2019. The EDRTM Radius Map Report with Geocheck. Target Property: Meridian AASF, 

1551 65th Ave S, Meridian, MS 39307. Inquiry Number: 5660870.2s. May 22, 2109.
Site Inspection Report

Army Aviation Support Facility #3, Meridian, Mississippi 

AECOM 9-2

Fenneman, N.M. 1917. Physiographic Subdivision of the United States. Proceedings of the 

National Academy of Sciences of the United States of America, Vol. 3, No.1 (Jan. 15, 

1917), pp. 17-22.

Fenneman, N.M. 1928. Physiographic Divisions of the United States. Annals of the Association of 

American Geographers, Vol. 18, No. 4 (December 1928), pp. 261-353. 

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.

Higgins, C.P., and Luthy, R.G. 2006. Sorption of Perfluorinated Surfactants on Sediments. 

Environmental Science and Technology 40 (23): 7251-7256.

ITRC. 2018. Environmental Fate ant Transport for Per- and Polyfluoroalkyl Substances. March. 

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

Acid at Key Field, Mississippi. Contract Number W9133L-14-D-0007; Task Order Number 

0009. January. 

Mississippi Automated Resource Information System. 2009. Mississippi USGS Wells 2009. 

Accessed 25 October 2022 at 

https://www.arcgis.com/home/webmap/viewer.html?url=https%3A%2F%2Fgis.mississipp

i.edu%2Fserver%2Frest%2Fservices%2FHosted%2FMS_USGSWells_2009%2FFeatur

eServer&source=sd. 

Mississippi State University. 2022. Office of the Mississippi State Climatologist. Mississippi 

Climate. Accessed 25 October 2022 at https://www.geosciences.msstate.edu/stateclimatologist/climate/. 

MSARNG. 2017. AASF 3 Meridian, Final Storm Water Pollution Prevention Plan, Volume 2. 

Natural Atlas. 2022. Chickasawhay River. Accessed 25 October 2022 at 

https://naturalatlas.com/rivers/chickasawhay-954728. 

The Meridian Star. 2010. Chickasawhay River Fishing. Accessed 25 October 2022 at 

https://www.meridianstar.com/sports/outdoors/chickasawhay-riverfishing/article_b9e9220b-4bc5-50ea-9de5-f5831e216b26.html. 

USACE. 2016. Technical Project Planning Process, EM-200-1-2. 26 February.

USEPA. 1980. Comprehensive Environmental Response, Compensation, and Liability Act

(CERCLA). 

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

40 CFR Part 300; 59 Federal Register 47384. September.

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

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

Assessments). December.

USEPA. 2017. National Functional Guidelines for Organic Superfund Data Review. OLEM

9355.0-136, EPA-540-R-2017-002. Office of Superfund Remediation and Technology

Innovation. January.

USFWS. 2019. National Wetlands Inventory, Wetlands Mapper. Accessed at

https://www.fws.gov/wetlands/data/mapper.html. 
Site Inspection Report

Army Aviation Support Facility #3, Meridian, Mississippi 

AECOM 9-3

USFWS. 2022. Information for Planning and Consultation: Lauderdale, Mississippi. 

Environmental Conservation Online System. Accessed 6 September 2022 at

https://ipac.ecosphere.fws.gov/location/SSYHPP2J5NH3VCCI5CYAKUOGH4/resources 

USGS. 1998. Ground Water Atlas of the United States: Segment 5, Arkansas, Louisiana, 

Mississippi. Hydrologic Atlas 730-F. 

USGS. 2019. National Water Information System. USGS Groundwater Data for the Nation. 

Accessed September 2019 at https://waterdata.usgs.gov/nwis/gw. 

World Climate. 2022. Average Weather Data for Meridian, Mississippi. Accessed 25 October 2022 

at http://www.worldclimate.com/climate/us/mississippi/meridian. 

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

and Perfluorooctanoate (PFOA) in Soils and Groundwater of a U.S. Metropolitan Area: 

Migration and Implications for Human Exposure. Water Research 72: 64-74.