FINAL

Site Inspection Report 

Fresno Aviation Classification 

Repair Activity Depot (AVCRAD)

Fresno, California

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 

September 2023

Prepared for:

Army National Guard Bureau

111 S. George Mason Drive

Arlington, VA 22204

UNCLASSIFIED
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Table of Contents

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

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

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

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

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

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

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

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

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

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

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

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

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 Hangar Training Area ..................................................................................3-1

3.2 AOI 2 Wash Rack and East Airfield Taxiway..........................................................3-1

3.3 AOI 3 Corrosion Control Facility ............................................................................3-1

3.4 Adjacent Sources ..................................................................................................3-2

3.4.1 Fresno Air National Guard Base..................................................................3-2

3.4.2 Fresno ARFF...............................................................................................3-2

3.4.3 Former Fire Training Area #1.......................................................................3-2

3.4.4 Former Fire Training Area #2.......................................................................3-2

3.4.5 Private Aviation Companies at Fresno Yosemite International Airport..........3-3

3.4.6 Former Marine Corps Facility ......................................................................3-3

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

6. Site Inspection Results .................................................................................................6-1
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6.1 Screening Levels...................................................................................................6-1

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

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

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

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

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

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

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

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

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

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

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

6.5.2 AOI 3 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

7.1.3 AOI 3...........................................................................................................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

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

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

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

8.3 Uncertainties .........................................................................................................8-3

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. Nonconformance and Corrective Action Reports

B5. Survey Data

Appendix C Photographic Log

Appendix D TPP Meeting Minutes

Appendix E Boring Logs and Well Construction Forms 

Appendix F Analytical Results

Appendix G Laboratory Reports

Figures

Figure 2-1 Facility Location

Figure 2-2 Facility Topography

Figure 2-3 Groundwater Features

Figure 2-4 Groundwater Elevations, February 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

Figure 7-3 Conceptual Site Model, AOI 3

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 5-3 Permanent Monitoring Well Screen Intervals and Groundwater Elevations

Table 6-1 Screening Levels (Soil and Groundwater)

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

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

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

Table 6-5 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

AECOM AECOM Technical Services, Inc.

AFFF aqueous film-forming foam

amsl above mean sea level

AOI Area of Interest

ARNG Army National Guard

AVCRAD Aviation Classification Repair Activity Depot

bgs below ground surface 

CAARNG California Army National Guard

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act 

CoC chain of custody

CSM conceptual site model

CSWRCB California State Water Resources Control Board 

DA Department of the Army

DoD Department of Defense

DO dissolved oxygen

DQO data quality objective

DUA data usability assessment

ELAP Environmental Laboratory Accreditation Program

EM Engineer Manual

FedEx Federal Express

FRB Field Reagent Blank

FTA Fire Training Area

GAMA Groundwater Ambient Monitoring and Assessment Program

HA Health Advisory

HAZMAT hazardous materials

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

NELAP National Environmental Laboratory Accreditation Program

ng/L nanograms per liter

OSD Office of the Secretary of Defense

PA Preliminary Assessment

PFAS per- and polyfluoroalkyl substances

PFBS perfluorobutanesulfonic acid

PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid
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PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

PID photoionization detector

PQAPP Programmatic UFP-QAPP

PVC polyvinyl chloride

QA quality assurance

QAPP Quality Assurance Project Plan

QC quality control

QSM Quality Systems Manual

SI Site Inspection

SL screening level

SOP standard operating procedure

SWRCB California State Water Board

TASMG Theater Aviation Sustainment Maintenance Group

TOC total organic carbon

TPP Technical Project Planning

UCMR3 Third Unregulated Contaminant Monitoring Rule

UFP Uniform Federal Policy

US United States

USACE United States Army Corps of Engineers

USCS Unified Soil Classification System

USEPA United States Environmental Protection Agency

USFWS United States Fish and Wildlife Service

USGS United States Geological Survey
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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 

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

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

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

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

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

compounds. This SI was completed at the Fresno Aviation Classification Repair Activity Depot 

(AVCRAD) in Fresno, California and determined no further evaluation under the Comprehensive 

Environmental Response, Compensation, and Liability Act (CERCLA) is warranted. The Fresno 

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

The Fresno AVCRAD is located at 5168 East Dakota Avenue, Fresno, California and is occupied 

by the 1106th Theater Aviation Sustainment Maintenance Group. Fresno AVCRAD occupies 

approximately 48 acres of land and is situated in the center of San Joaquin Valley, in the southern 

portion of California’s Central Valley. The mission of the AVCRAD is to provide support of ARNG 

aviation activities through depot-level and limited aviation intermediate unit maintenance. The 

facility serves as a maintenance shop for rotary wing aircraft. The AVCRAD includes four main 

buildings (hangar, armory, ground support equipment building, and corrosion control facility) and 

related infrastructure including roadways, parking lots, aircraft parking areas, and taxi lanes. The 

facility is categorized as a large-quantity hazardous waste generator because it houses several 

oil storage locations and manages a variety of hazardous materials (AECOM Technical Services, 

Inc. [AECOM], 2020). 

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

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

Based on the results of this SI, no further evaluation under CERCLA is warranted for each of the 

three AOIs at this time. 

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

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

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

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

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

individual chemical of concern in the absence of other PFAS. 
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AECOM ES-2

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 

Area

Groundwater – 

Source Area

Groundwater 

– 

Facility 

Boundary

Future Action

1 Hangar Training 

Area N/A

No further 

action at this 

time

2 Wash Rack and East 

Airfield Taxiway N/A

No further 

action at this 

time

3 Corrosion Control 

Facility N/A N/A

No further 

action at this 

time

Legend:

N/A = not applicable 

= detected; exceedance of the screening levels

= detected; no exceedance of the screening levels

= not detected
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AECOM 1-1

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 Fresno Aviation 

Classification Repair Activity Depot (AVCRAD) in Fresno, California. Fresno AVCRAD 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 Fresno AVCRAD (AECOM Technical Services, Inc. [AECOM], 2020) that

identified three 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

The Fresno AVCRAD is located at 5168 East Dakota Avenue, Fresno, California and is occupied 

by the 1106th Theater Aviation Sustainment Maintenance Group (TASMG). The mission of the 

AVCRAD is to provide support of ARNG aviation activities through depot-level and limited aviation 

intermediate unit maintenance. The AVCRAD provides support to 13 western states, 18 Army 

Aviation Support Facilities, and over 500 rotary wing aircrafts (Radian International, 1999). 

California ARNG (CAARNG) leased property from the city of Fresno Airport Authority starting in 

1978, and the AVCRAD property was constructed in approximately 1985. The lease was recently 

amended to extend to 2058 (Radian International, 1999; CAARNG Real Estate Manager, 2019). 

The facility borders the Fresno Yosemite International Airport to the northeast and is situated in 

the center of San Joaquin Valley, in the southern portion of California’s Central Valley (Figure 2-

1). The facility is about 115 miles east of the Pacific Ocean and 170 miles south of Sacramento. 

The latitude, longitude, and surface elevation at the main gate of the facility are 36°47’11.2” N; 

119°43’11.6” W, and 350 feet above mean sea level (amsl), respectively. The facility consists 

largely of paved surfaces and buildings, with limited permeable, unpaved areas located in the 

southwestern portion.

2.2 Facility Environmental Setting

Fresno AVCRAD occupies approximately 48 acres of land that are primarily composed of 

impervious surfaces. In addition to the adjoining Fresno Yosemite International Airport, residential 

communities are to the north of the facility, and commercial areas are to the northeast and east. 

Fresno AVCRAD is in a relatively flat area with no significant natural topographic features. The 

surface elevation ranges from 326 to 344 feet amsl. The general topographic gradient is west/ 

southwest (Figure 2-2). 

2.2.1 Geology

Fresno AVCRAD is located along the eastern margin of California’s San Joaquin Valley. In the 

San Joaquin Valley, the principal freshwater-bearing units are the unconsolidated deposits that 

extend to depths of 3,500 feet below ground surface (bgs). The unconsolidated valley floor 

alluvium deposits are characterized by fine-grained silt and sand. Localized clay beds are also 

common below 200 feet bgs. Finer-grained sediments, such as silts and clays, are associated 

with overbank and floodplain deposits, whereas coarser sediments, such as sands and gravels, 

are associated with levee, channel lag, and point bar deposits (BB&E, Inc. 2016).

The Sierra Nevada Mountains form the physiographic barrier on the eastern side of the San

Joaquin Valley. Groundwater stored in the alluvial deposits is bounded on the eastern flanks and 

below by the consolidated Cretaceous and Tertiary sedimentary rocks and Sierra Nevada granitic 

rocks. Water-bearing zones contain a higher percentage of sand compared to the intervening 

aquitards, which are primarily silt with secondary sand and clay (Page and LeBlanc, 1969). 

(Figure 2-3). 

Soil borings completed during the SI found silty sand and silt with sand as the dominant lithology 

of the unconsolidated sediments below Fresno AVCRAD. The borings were completed at depths 

between 137 and 140 feet bgs. Lesser amounts of poorly graded sand were observed in the 

borings, in layers ranging from 1 to 5 feet thick. Isolated clay layers were also observed and 

ranged from 2 to 7 feet thick. These observations are consistent with the understood lithology 

characterizing a fluvial-dominated alluvial fan depositional environment. 
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AECOM 2-2

2.2.2 Hydrogeology

Fresno AVCRAD lies within the Kings Sub-basin of the San Joaquin Valley Groundwater Basin. 

Groundwater is found in the unconfined or semi-confined conditions within alluvial fan deposits in 

the eastern portion of the Central Valley, where Fresno AVCRAD is located. Seven water-bearing 

zones have been identified in the vicinity of the AVCRAD. 

As indicated in the PA report, 21 wells are located within a one-mile radius of the Fresno AVCRAD 

(AECOM, 2020). Eleven (11) of the 21 wells are listed as federal US Geological Survey (USGS) 

wells. The remaining 10 wells are listed as water wells on the California Wells database. Potable 

water is supplied by City of Fresno public water supply wells, and base personnel have indicated 

that there is a city pump station located adjacent to the eastern facility property line, approximately 

50 feet away. According to data on the publicly available Geotracker Groundwater Ambient 

Monitoring and Assessment (GAMA) online tools maintained by the California State Water 

Resources Control Board (SWRCB), PFAS sampling was conducted between June 2019 to 

February 2021 from one of two drinking water wells at the adjacent city pump station. As of 

February 2021, PFOS was detected at 4.4 nanograms per liter (ng/L), and PFOA, PFBS, PFHxS, 

and PFNA were not detected above the reporting limit of 2 ng/L (SWRCB, 2021). Based on the 

USEPA Unregulated Contaminant Monitoring Rule 3 (UCMR3) data, PFOA, PFOS, PFBS, 

PFHxS, and PFNA were not reported in a public water system above the detection limits within 

20 miles of the facility (USEPA, 2017a). PFAS analyses performed in 2016 had method detection 

limits that were higher than currently available. Thus, it is possible that low concentrations of PFAS 

were not detected during the UCMR3 but might be detected if analyzed today.

According to well database entries provided in the PA report, groundwater depth readings taken 

in 1963 ranged from 54.56 to 73.85 feet bgs in six USGS wells. However, groundwater levels 

have since declined due to extensive regional pumping and are estimated at a depth greater than 

80 feet bgs (ERM-West, Inc., 1998). Based on historical information, the regional groundwater 

flow direction is inferred to be primarily east. Groundwater features are presented on Figure 2-3. 

Groundwater was measured in a 2018 SI at the adjacent Fresno Air National Guard Base, located 

approximately 1.3 miles southeast of Fresno AVCRAD. Depth to groundwater ranged from 111 to 

130 feet bgs, and the groundwater flow direction was northwest (AECOM, 2019a). 

Depth to water was measured at two newly installed monitoring wells, AVCRAD-MW001 and 

AVCRAD-MW002R, in June and September 2021, respectively. Both wells were gauged 

synoptically in February 2022. During the February 2022 well gauging event, depth to water was 

measured at 125.73 feet bgs at AVCRAD-MW001 and 124.94 feet bgs at AVCRAD-MW002R. 

Groundwater elevations from the SI are presented on Figure 2-4 and the inferred localized 

groundwater flow direction is to the northwest. Groundwater contours could not be drawn, as data 

at the site are limited to two points. The well AVCRAD-MW002 is shown on this map and in Table 

5-3, however, it was abandoned after installation due to an obstruction in the well screen; thus,

the groundwater elevation shown is for informational purposes only and may not be accurately

representative of site conditions.

2.2.3 Hydrology 

Surface water at AVCRAD runs southwest and joins the Fresno Yosemite International Airport 

drainage system (Figure 2-5). This drainage system then flows south into Mills Creek (canal along 

McKinley Avenue) and feeds into Herndon Canal. The Herndon Canal is a tributary to the San 

Joaquin River, which eventually discharges into the San Francisco Bay (HazCon, 2017).

Storm water is drained radially outwards in the facility airfield and is captured in the storm drains 

located around the airfield boundary. The storm drainage system on the western side of the 

AVCRAD facility has a gate valve that can be manually shut to control the release of storm water. 
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AECOM 2-3

The facility has no water treatment system, and the two oil-water separators associated with the 

Wash Rack and Corrosion Control Facility are connected to the Fresno sanitary sewer system. 

Surface water features are presented on Figure 2-5. 

2.2.4 Climate 

Fresno AVCRAD is in a semi-arid, Mediterranean climate zone characterized by warm, dry 

weather from June through September, and mild, rainy weather from November through March. 

The average annual rainfall is approximately 11.5 inches, with the majority of the rainfall occurring 

between late fall and early spring. Summer temperatures peak in July and August, with an 

average temperature of 82.3 degrees Fahrenheit (°F), and winter temperatures are lowest in 

December to January, with an average temperature of 46.7 °F. Snowfall is rare, but frost occurs 

occasionally (National Oceanic and Atmospheric Administration, 2019). 

2.2.5 Current and Future Land Use

Fresno AVCRAD serves as a maintenance shop for rotary wing aircraft. The AVCRAD includes 

four main buildings (hangar, armory, ground support equipment building, and corrosion control 

facility) and related infrastructure, including roadways, parking lots, aircraft parking areas, and 

taxi lanes. The facility is categorized as a large-quantity hazardous waste generator because it 

houses several oil storage locations and manages a variety of hazardous materials (HAZMAT). 

The current lease with the city of Fresno Airport Authority is set to expire in 2058 (CAARNG Real 

Estate Manager, 2019). Reasonably anticipated future land use is not expected to change from 

the current land use described above. 

2.2.6 Sensitive Habitat and Threatened/ Endangered Species 

The following birds, plants, mammals, and reptiles are federally endangered, threatened, 

proposed, and/ or are listed as candidate species in Fresno County, California (US Fish and 

Wildlife Service [USFWS], 2021). 

• Insects: Monarch butterfly, Danaus plexippus (candidate); Valley elderberry longhorn

beetle, Desmocerus californicus dimorphus (threatened)

• Amphibians: California tiger Salamander, Ambystoma califoriense (endangered);

Mountain yellow-legged frog, Rana muscosa (endangered); Sierra Nevada Yellow-legged

Frog, Rana sierrae (endangered), California red-legged frog, Rana draytonii (threatened);

Yosemite Toad, Anaxyrus canorus (threatened)

• Birds: California Condor, Gymnogyps californias (endangered); Yellow-billed Cuckoo,

Coccyzus americanus (threatened)

• Mammals: Northern long-eared bat, Myotis septentrionalis (threatened);

• Flowering plants: Greene's tuctoria, Tuctoria greenei (endangered), California jewelflower,

Caulanthus califonicus (endangered); Hairy Orcutt grass, Orcuttia pilosa (endangered);

Hartwig’s golden sunburst, Pseudopahia bahiifolia (endangered); San Joaquin woolythreads, Monolopia Lembertia congdonii (endangered)

2.3 History of PFAS Use

Five potential release areas were identified at the Fresno ACVRAD during the PA where AFFF 

may have been used or released historically (AECOM, 2020). These areas include the Hangar 

Training Area, the Wash Rack & East Airfield Taxiway (including the HAZMAT locker), and the 

Corrosion Control Facility (AECOM, 2020). PFAS-containing AFFF was released during fire 
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AECOM 2-4

training activities at the Hangar Training Area and may have been incidentally spilled to the ground 

surface in controlled releases at the Wash Rack & East Airfield Taxiway. Additionally, a leak in the 

AFFF fire suppression system in the Corrosion Control Facility may have caused a release to 

floor drains in the building. The potential release areas were grouped into three AOIs, AOI 1, AOI 

2, and AOI 3, based on proximity to one another and presumed groundwater flow. Descriptions of 

the AOIs are presented in Section 3. 
CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

EB

8/2/2022

8/2/2022

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3. Summary of Areas of Interest

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

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

identified at Fresno AVCRAD and grouped into three AOIs. Additionally, numerous adjacent 

potential release areas were identified during the PA, including the Fresno Air National Guard 

Base, Signature Fixed Based Operation Hangar, Fresno Aircraft Rescue and Firefighting, Former 

Fire Training Areas, and Former Marine Corps Facility (AECOM, 2020). The potential release 

areas are shown on Figure 3-1. 

3.1 AOI 1 Hangar Training Area

AOI 1 is the Hangar Training Area, which borders the AVCRAD Hangar to the west. Controlled 

AFFF releases through fire training activities occurred annually during the approximate years 

2008 to 2011 and 2014.

AOI 1 lies within the San Joaquin Valley Groundwater Basin, and all surface water is eventually 

drained by tributaries to the San Joaquin River. PFAS are water soluble and can migrate readily 

from soil to groundwater or surface water via leaching and run-off. If PFAS releases to surface 

and subsurface soil occurred, it is possible that PFAS migrated from surface soil at AOI 1 to 

groundwater and waters in the San Joaquin River. Drinking water is supplied by city of Fresno 

water supply wells. The closest city pump station was indicated to lie adjacent to the eastern 

facility property line, approximately 50 feet away from the AOI. In addition, precipitation infiltrating 

into the grassy surrounding areas of the AOI may cause the migration of PFAS from surface and 

subsurface soil to groundwater and surface water. 

3.2 AOI 2 Wash Rack and East Airfield Taxiway 

AOI 2 is the Wash Rack and East Airfield Taxiway. The area includes the HAZMAT locker with 

AFFF storage, located at the southeast corner of the Wash Rack. Controlled AFFF releases to 

the Wash Rack have occurred periodically from 2007 to 2010, and AFFF releases in the two 

identified areas from the servicing of Tri-MaxTM fire extinguishers in the East Airfield Taxiway have 

occurred in 2015. 

The Wash Rack contains an oil-water separator that drains to the Fresno sanitary sewer. 

However, base personnel have indicated that the wash rack drains were typically plugged during 

training events. Therefore, during events when the wash rack drains were plugged, potentially 

contaminated surface water at AOI 2 may have been captured in surrounding storm drains, which 

carry water towards Mills Creek and eventually to San Joaquin River. If PFAS were released to 

surface soil at AOI 2, they would have potential to migrate from surface soil to surface water via 

run-off and to groundwater via leaching. The nearest water supply well to AOI 2 is east of the AOI, 

approximately 50 feet away. The pathways and receptors for AOI 2 are the same as AOI 1 

described in above section.

3.3 AOI 3 Corrosion Control Facility

AOI 3 is the corrosion control facility, which is located south of the airfield. The facility contains an 

AFFF fire suppression system with a 1,100-gallon capacity AFFF tank containing 3 percent (%) 

AFFF. A small drip leak at fire suppression system was reported approximately six to eight months 

after the system installation in June 2011. Leak repair and cleaning occurred approximately one 

week after the incident was reported. A large floor drain is located in the facility, but it is unknown 

whether the drain leads to the sanitary sewer or storm drain system. If PFAS-contaminated water 

were captured in the storm water drainage system, it would eventually discharge to San Joaquin 
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AECOM 3-2

River. If PFAS were released to surface soil at AOI 3, it may have migrated from the surface soil 

to surface water through runoff or to groundwater through infiltration at grassy areas. The 

pathways and receptors for AOI 3 are the same as AOI 1 described in above section.

3.4 Adjacent Sources

Numerous potential off-facility sources of PFAS adjacent to the TASMG, not under the control of 

the CAARNG, were identified during the PA. The adjacent potential sources are shown on 

Figure 3-1 and described in the following sections for informational purposes only and were not 

investigated as part of this SI. These facilities are all located nominally cross-gradient to the 

Fresno AVCRAD facility.

3.4.1 Fresno Air National Guard Base

Fresno ANGB is located on a 111-acre leased property on the southeast corner of the Fresno 

Yosemite International Airport. Fresno ANGB is home to the 144th Fighter Wing, and operations 

related to the use and/or storage of AFFF have historically occurred at various locations at Fresno 

ANGB. A 2016 PA report on PFAS identified nine potential release locations (PRLs) (BB&E, Inc. 

2016). A 2018 SI report for the Fresno ANGB confirmed that PFOS concentrations in soil at one 

PRL exceeded the USEPA residential soil regional screening level (RSL), and PFOA 

concentrations in groundwater at three PRLs exceeded the Health Advisories (AECOM, 2019).

3.4.2 Fresno ARFF

The Fresno ARFF has a fire station on Fresno Yosemite International Airport property and 

provides emergency response to aircraft emergencies. The fire station stores 3% AFFF and 

contains a firetruck with a 500-gallon AFFF and 3000-gallon water capacity with proportioning 

valves to mix the concentrate with water. Nozzle testing with water regularly occurs in all areas of 

the airport property. In addition, the ARFF conducts bi-annual foam testing for Federal Aviation 

Administration (FAA) certification. Approximately 30-50 gallons of 3% AFFF in the concentrated 

form are released from the firetruck during each testing event. Three testing areas were identified 

during interviews with ARFF personnel. One testing area was outside the ARFF fire station, and 

the other two areas were located southeast of the Fresno AVCRAD. 

3.4.3 Former Fire Training Area #1

A former FTA is located on Fresno Yosemite International Airport. According to interviews with 

Fresno ARFF personnel, the FTA was utilized by both the ANGB and ARFF in combined annual 

training events during the estimated years of 1989 to 2000. The FTA contained a mock-up aircraft 

in a lined fire pit with a fuel pumping system. Training reportedly consisted of igniting fuel within 

the fire pit or in the mock-up aircraft and then extinguishing the resulting fire with AFFF. The 

frequency, volume, and concentration of AFFF used in this FTA are unknown. 

3.4.4 Former Fire Training Area #2

A former FTA is located on Fresno Yosemite International Airport. According to interviews with 

Fresno ARFF personnel, the FTA was utilized by both the ANGB and ARFF in combined annual 

training events during the estimated years of 2005 to 2008. The FTA contained an old city of 

Fresno bus that would be ignited with fuel and then extinguished with AFFF. The frequency, 

volume, and concentration of AFFF used in this FTA are unknown. 
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3.4.5 Private Aviation Companies at Fresno Yosemite International Airport

Signature Flight Support Corporation maintains two hangars with AFFF deluge systems on a 

parcel of land adjacent to R-11 Runway. On 16 October 2015, it was reported by ARFF personnel 

that the AFFF deluge system at the Signature Fixed Base Operator hangar had an accidental trip, 

which resulted in a release of AFFF.

3.4.6 Former Marine Corps Facility 

According to interviews with Fresno ARFF personnel, there was a former Marine Corp facility 

located approximately 0.5 miles southeast of the TASMG. The facility housed a Light Anti-Aircraft 

Missile Battalion, a United States Marine Corps air defense unit, and had a deployable fire unit 

with a P-19 firetruck. The current Fresno ARFF fire captain and former guardsman recounted that 

combined fire training was conducted with the Air National Guard in the area during the estimated 

years of 1990-1992. The Marine Corps leased the property from the Fresno Yosemite 

International Airport until approximately five years ago. A search on the Naval Facilities 

Engineering Command administrative record was made, but no information was readily available. 

Based on the timeline and operational use, it is possible AFFF could have been released or used 

during fire training exercises. 
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4. Project Data Quality Objectives

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

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

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

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

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

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

AOIs.

4.1 Problem Statement

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

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

SLs are presented in Section 6.1 of this report. 

4.2 Information Inputs

Primary information inputs included:

• The PA for Fresno AVCRAD (AECOM, 2020);

• Analytical data maintained by the SWRCB (SWRCB, 2021);

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

with the site-specific UFP-QAPP (AECOM, 2021a); and

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

parameters measured at the time of sampling.

4.3 Study Boundaries

The scope of the SI was bounded by the property limits of the facility (Figure 2-2). Off-facility sampling 

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

stakeholders will be notified, and necessary rights of entry will be obtained by ARNG with property 

owner(s).

4.4 Analytical Approach

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

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

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

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

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

4.5 Data Usability Assessment

The Data Usability Assessment (DUA), which is provided in Appendix A, is an evaluation at the 

conclusion of data collection activities that uses the results of both data verification and validation 

in the context of the overall project decisions or objectives. Using both quantitative and qualitative 

methods, the assessment determines whether project execution and the resulting data have met 

installation-specific DQOs. Both sampling and analytical activities are considered to assess 
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AECOM 4-2

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

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

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

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

requirements of the SI QAPP Addendum (AECOM, 2021a). 
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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, Fresno TASMG, Fresno, California dated February

2020 (AECOM, 2020);

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

Fresno AVCRAD, Fresno, California dated May 2021 (AECOM, 2021a);

• Final Site Safety and Health Plan, Fresno AVCRAD, Fresno, California dated May 2021

(AECOM, 2021b).

The SI field activities were conducted from 15 June to 14 September 2021 and February 2022 and 

consisted of utility clearance, sonic boring, soil sample collection, permanent monitoring well 

installation, grab groundwater sample collection, and land surveying. Field activities were conducted 

in accordance with the SI QAPP Addendum (AECOM, 2021a), except as noted in Section 5.8. 

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

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

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

• Twelve (12) soil samples from two (2) boring locations and six surface soil locations;

• Two (2) grab groundwater samples from two (2) newly installed permanent well locations;

• Eleven (11) 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, Nonconformance and Corrective Action Reports are provided in 

Appendix B4, and land survey data are provided in Appendix B5. 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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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 20 January 2021, prior to SI field activities. The 

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

stakeholders for this SI include the ARNG, CAARNG, USACE, the Regional Water Quality Control 

Board, 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, 2021a). 

A TPP Meeting 3 was held on 16 June 2023 to discuss the results of the SI. Meeting minutes for 

TPP 3 are included in Appendix D of this report. Future TPP meetings will provide an opportunity 

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

5.1.2 Utility Clearance

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

Alert” Southern California utility clearance provider to notify them of intrusive work on 04 June 

2021 and 12 August 2021. However, because Fresno AVCRAD is a private facility, the 

participating “Dig Alert” locators did not clear utilities at the entire facility. Therefore, AECOM 

contracted Ground Penetrating Radar Systems, LLC., a private utility location service, to perform 

utility clearance. Underground Surveying, LLC. performed utility clearance of the proposed boring 

locations on 17 March 2021 and 17 August 2021 with input from the AECOM field team and 

Fresno AVCRAD facility staff. General locating services and ground-penetrating radar were used 

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

hand auger to verify utility clearance in shallow subsurface where utilities would typically be 

encountered.

5.1.3 Source Water and Sampling Equipment Acceptability

The potable water source used for decontamination of drilling equipment was confirmed to be 

acceptable for use in a PFAS investigation prior to the start of field activities. A sample from a 

potable water source at Fresno AVCRAD was collected on 17 March 2021, prior to mobilization, 

and analyzed by LC/MS/MS compliant with QSM 5.3 Table B-15. The results of the 

decontamination water sample are provided in Appendix F. A discussion of the results is 

presented in the DUA (Appendix A).

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

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

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

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

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

member regarding the allowable materials within the sampling environment. 

5.2 Soil Borings and Soil Sampling

Soil samples were collected via sonic drilling technology, in accordance with the SI QAPP 

Addendum (AECOM, 2021a). A track-mounted Prosonic 600T and truck-mounted Boart 

LongyearTM LSTM600 were used to collect continuous soil cores to the target depth. A hand auger 

was used to collect soil from the top five feet of the boring, in accordance with AECOM utility 

clearance procedures. The soil boring locations are shown on Figure 5-1, and depths are 

provided Table 5-2. 
Site Inspection Report

Fresno AVCRAD, Fresno, California

AECOM 5-3

Three discrete soil samples were collected from the vadose zone for chemical analysis from each 

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

2 feet above the groundwater table, and one subsurface soil sample from 13 to 15 feet bgs. Due 

to the presence of groundwater at a depth greater than 15 feet bgs, mid-point samples were taken 

from the 13 to 15 feet bgs interval, in accordance with the QAPP Addendum (AECOM, 2021a). 

The soil cores were continuously logged for lithological descriptions by a 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 non-treated field 

logbook (i.e., composition notebook). Depth interval, recovery thickness, PID concentrations, 

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

were recorded. The boring logs are provided in Appendix E. 

Soil borings completed during the SI found silty sand and silt with sand as the dominant lithology 

of the unconsolidated sediments below Fresno AVCRAD. The borings were completed at depths 

between 137 and 140 feet bgs. Lesser amounts of poorly graded sand were observed in the 

borings, in layers ranging from 1 to 5 feet thick. Isolated clay layers were also observed and 

ranged from 2 to 7 feet thick. These Site observations are consistent with the understood lithology 

characterizing a fluvial-dominated alluvial fan depositional environment. 

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

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

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

to the laboratory and analyzed for PFAS (LC/MS/MS compliant with QSM 5.3 Table B-15), total 

organic compounds ([TOC]; USEPA Method 9060A) and pH (USEPA Method 9045D) in 

accordance with the SI QAPP Addendum (AECOM, 2021a). 

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

as the accompanying samples. Matrix spike (MS)/MS duplicates (MSDs) were collected at a rate 

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

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

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

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

preserved at or below 6 degrees Celsius (°C) during shipment.

Sonic borings were converted to permanent monitoring wells. Borings were installed in grass 

areas to avoid disturbing concrete or asphalt surfaces.

5.3 Permanent Well Installation and Groundwater Sampling

During the initial mobilization for SI field activities in June 2021, two permanent monitoring wells 

were installed within or downgradient of potential source areas. Due to an obstruction of the well 

screen at AVCRAD-MW002, it was determined that the well could not be developed or 

subsequently sampled. Field staff remobilized in August 2021 to install a replacement well near 

the original location (AVCRAD-MW002R) and abandoned the original well. The original well 

location was overdrilled to remove the well materials and backfilled with grout. Due to the proximity 

of the replacement well, additional soil samples were not collected at this location. The location 

of AVCRAD-MW001, the original well location for AVCRAD-MW002, and the location of 

replacement well AVCRAD-MW002R are shown on Figure 5-1. 

A track-mounted Prosonic 600T and truck-mounted Boart LongyearTM LSTM600 drill rig were used 

to install two 2-inch diameter monitoring wells. The monitoring wells were constructed with 

Schedule 40 polyvinyl chloride (PVC), flush threaded 10-foot sections of riser, 0.010-inch slotted 

well screen, and a threaded bottom cap. A filter pack of 20/40 silica sand was installed in the 
Site Inspection Report

Fresno AVCRAD, Fresno, California

AECOM 5-4

annulus around the well screen to a minimum of 2 feet above the well screen. A 3-foot-thick 

bentonite seal was placed above the filter sand and hydrated with distilled water. Bentonite grout 

was placed in the well annulus from the top of the bentonite seal to ground surface. The bentonite 

grout was allowed to set for 24 hours prior to well completion in accordance with the SI QAPP 

Addendum (AECOM, 2021a). All monitoring wells were completed with flush mount well vaults.

The screen interval of each of the groundwater monitoring wells is provided in Table 5-3. 

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

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

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

levels were measured to the nearest 0.01 inch and recorded. Samples were collected no sooner 

than 24 hours following development using HDPE HydrasleevesTM, in accordance with the SI 

QAPP Addendum (AECOM, 2021b). Since the HydrasleeveTM is a PFAS-free and disposable 

passive sampler, this sampling method minimized the potential for cross contamination, negated 

the need for decontamination, and minimized the amount of purge water generated. Water quality 

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

reduction potential) were measured during well development using a water quality meter and 

recorded on the well development sampling form (Appendix B2). Additionally, a subsample of 

each groundwater sample was collected in a separate container and a shaker test was completed 

to identify if there was any foaming. No foaming was noted in any of the groundwater samples.

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

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

standard CoC procedures to the laboratory and analyzed for PFAS by LC/MS/MS compliant with 

QSM 5.3 Table B-15 in accordance with the SI QAPP Addendum (AECOM, 2021a).

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

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

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

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

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

5.4 Synoptic Water Level Measurements

A synoptic groundwater gauging event was performed on 3 February 2022. Depth to groundwater 

measurements were collected from the two new permanent monitoring wells and used to calculate 

groundwater elevations. Water level measurements were taken from the northern side of the well 

casing. A groundwater elevation 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 California-licensed land surveyors 

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

Survey data from the newly installed wells on the facility were collected on 23 June 2021 and 2 

August 2021 in the applicable Universal Transverse Mercator zone projection with World Geodetic 

System 84 datum (horizontal) and North American Vertical Datum 1988 (vertical). The surveyed 

well data are provided in Appendix B5. 

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

Fresno AVCRAD, Fresno, California

AECOM 5-5

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

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

Soil IDW (i.e., soil cuttings) generated during the SI activities were containerized in properlylabeled 55-gallon drums and stored in a location identified by CAARNG. The soil IDW was not 

sampled and assumes the PFAS characteristics of the associated soil samples collected from 

that source location. ARNG has coordinated waste profiling, transportation, and disposal of the 

solid IDW under a separate contract. 

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

decontamination fluids) was containerized in properly-labeled 55-gallon drums and stored in a 

location identified by CAARNG. The liquid IDW was not sampled and assumes the PFAS 

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

on laboratory results, containerized liquid IDW will be managed and disposed by ARNG (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).

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

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

activities were disposed of at a licensed solid waste landfill.

5.7 Laboratory Analytical Methods

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

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

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

5.8 Deviations from SI QAPP Addendum

Four deviations from the SI QAPP Addendum were identified during review of the field 

documentation. The deviations are noted below and documented in a Field Change Request 

Form (Appendix B3) and Nonconformance and Corrective Action Reports (Appendix B4): 

• After the installation of two permanent monitoring wells in June 2021, the screen in one well

(AVCRAD-MW002) appeared obstructed during development. As a result, it was

determined that this well was damaged, and a new well would have to be installed before

the two wells could be sampled. A replacement well (AVCRAD-MW002R) was installed and

subsequently developed in August 2021, allowing both newly installed permanent wells to

be sampled for groundwater. This action was documented in a field change request form

provided in Appendix B3.

• Upon review of field documentation, it was discovered that an FRB was not collected during

the field effort. Additionally, a Field Duplicate and MS/MSD were not collected for

groundwater samples. This action was documented in a nonconformance and corrective

action report provided in Appendix B4.

Prior to groundwater sampling, water quality parameters were not recorded to the extent stated 

in the SI QAPP Addendum. Stabilized water quality parameters collected during monitoring well 

development may be used in lieu of measurements not collected during groundwater sampling. 

This action was documented in a nonconformance and corrective action report provided in 

Appendix B4. 
Site Inspection Report

Fresno AVCRAD, Fresno, California

AECOM 5-6

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Table 5-1

Site Inspection Samples by Medium

Site Inspection Report, Fresno AVCRAD, California

Sample Identification

Sample

Collection 

Date/Time

Sample Depth 

(feet bgs)

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

Comments

AVCRAD-MW001-SB-00-02 6/17/2021 13:25 0 - 2 x

AVCRAD-MW001-SB-00-02-D 6/17/2021 13:25 0 - 2 x FD

AVCRAD-MW001-SB-13-15 6/17/2021 16:00 13 - 15 x

AVCRAD-MW001-SB-124-125 6/21/2021 14:15 124 - 125 x

AOI01-01-SB-00-02 6/18/2021 8:30 0 - 2 x

AOI01-01-SB-00-02-MS 6/18/2021 8:30 0 - 2 x MS

AOI01-01-SB-00-02-MSD 6/18/2021 8:30 0 - 2 x MSD

AOI01-02-SB-00-02 6/17/2021 14:00 0 - 2 x x x

AOI01-02-SB-00-02-D 6/17/2021 14:00 0 - 2 x FD (pH, TOC)

AVCRAD-MW002-SB-00-02 6/15/2021 14:30 0 - 2 x

AVCRAD-MW002-SB-13-15 6/15/2021 15:30 13 - 15 x

AVCRAD-MW002-SB-124-125 6/16/2021 13:45 124 - 125 x

AOI02-01-SB-00-02 6/18/2021 12:00 0 - 2 x

AOI02-02-SB-00-02 6/17/2021 TIME? 0 - 2 x

AOI02-02-SB-00-02-MS 6/17/2021 TIME? 0 - 2 x x MS (pH, TOC)

AOI02-02-SB-00-02-MSD 6/17/2021 TIME? 0 - 2 x x MSD (pH, TOC)

AOI02-03-SB-00-02 6/18/2021 9:50 0 - 2 x

AOI03-01-SB-00-02 6/18/2021 12:20 0 - 2 x x x

AOI03-01-SB-00-02-D 6/18/2021 12:20 0 - 2 x x FD

AVCRAD-MW001-GW 9/14/2021 9:10 NA x

AVCRAD-MW002R-GW 9/14/2021 9:55 NA x

Collected from 

MW002R

CN-PW-01 3/17/2021 13:50 NA x Decon Source

CN-ERB-01 6/18/2021 12:25 NA x Hand Auger

CN-ERB-02 6/18/2021 13:30 NA x

Stainless-steel 

Bowl

CN-ERB-03 6/22/2021 14:35 NA x Hand Auger

Soil Samples

Quality Control Samples

Groundwater Samples

Notes:

ASTM = American Society for Testing and Materials

bgs = below ground surface

Decon Source = Source of water used for decontamination of equipment

ERB = equipment rinsate blank

FD = field duplicate

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

AECOM 5-7
Site Inspection Report

Fresno AVCRAD, Fresno, California

AECOM 5-8

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Table 5-2

Soil Boring Depths

Site Inspection Report, Fresno AVCRAD, California

Area of 

Interest

Boring 

Location

Soil Boring 

Depth 

(feet bgs)

1 AVCRAD-MW001 137

AVCRAD-MW002 137

AVCRAD-MW002R 140

Notes:

1 Permanent well screen set above total depth to capture groundwater interfaceAVCRAD = Aviation Classification Repair Activity Depotbgs = below ground surfacebtoc = below top of casingNA = not applicableNAVD88 = North American Vertical Datum 1988

2

AECOM 
Table 5-3

Permanent Well Screen Intervals and Groundwater Elevations

Site Inspection Report, Fresno AVCRAD, California

Area of 

Interest

Boring 

Location

Permanent Well 

Screen Interval 

(feet bgs)

Top of Casing 

Elevation 

(feet NAVD88)

Ground Surface 

Elevation 

(feet NAVD88)

Depth to Water

(feet btoc)

Depth 

(fee

1 AVCRAD-MW001 126 - 136 337.43 338.20 124.96 12

AVCRAD-MW002 125 - 135 337.91 338.14 122.00 12

AVCRAD-MW002R 125 - 135 337.57 338.05 124.46 12

Notes:

1 Permanent well screen set above total depth to capture groundwater interfaceAVCRAD = Aviation Classification Repair Activity Depot

bgs = below ground surfacebtoc = below top of casingNA = not applicableNAVD88 = North American Vertical Datum 1988

2

AECOM 
?!

?!

"S

"S "S

"S

"S

"S

?!

AOI 2

AOI 1

AOI 3

AVCRAD-MW001

AVCRAD-MW002

AOI01-01

AOI01-02

AOI02-02

AOI02-01

AOI02-03

AOI03-01

AVCRAD-MW002R

Legend

?! Soil Boring/Permanent Monitoring Well

"S Surface Soil Sample

Area of Interest

Facility Boundary

Surface Water Flow Direction

Inferred Groundwater Flow Direction

CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

MB

8/2/2022

8/2/2022

PROJECT Site Inspection at Fresno AVCRAD, CA

1:3,360

8/2/2022 ­ Figure 5-1 PM CM 8/2/2022

12420 Milestone Center Drive

Germantown, MD 20876

Site Inspection Sample Locations

Base Map: Source: Esri, Maxar, Earthstar Geographics,

and the GIS User Community

0 140 280 560

Feet

AECOM 5-11
Site Inspection Report

Fresno AVCRAD, Fresno, California

AECOM 5-12

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Site Inspection Report

Fresno AVCRAD, Fresno, California

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 6.5. 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, the AOI will proceed to the next phase under CERCLA. 

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

6-1 below.

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

Analyteb

Residential

(Soil)

(μg/kg)a 

0-2 feet bgs

Industrial/ 

Commercial 

Composite 

Worker

(Soil)

(μg/kg)a 

2-15 feet bgs

Tap Water

(Groundwater)

(ng/L)a

PFOA 19 250 6 

PFOS 13 160 4

PFBS 1,900 25,000 601 

PFHxS 130 1,600 39

PFNA 19 250 6 

Notes:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Fresno AVCRAD, Fresno, California

AECOM 6-2

6.2 Soil Physicochemical Analyses

To provide basic soil parameter information, 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: Hangar Training Area. 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 

6-4 summarize the soil results.

At AOI 1, soil was sampled from surface soil (0 to 2 feet bgs), shallow subsurface soil (13 to 15 

feet bgs), and deep subsurface soil (124 to 125 feet bgs) from boring location AVCRAD-MW001. 

Soil was also sampled from the surface soil (0 to 2 feet bgs) at locations AOI01-01 and AOI01-

02. PFBS was not detected at any soil sampling locations in AOI 1. In the deep subsurface soil,

PFOA, PFOS, PFBS, PFHxS, and PFNA were not detected.

In the surface soil, PFOA was detected at two of four locations at concentrations ranging between 

0.269 J micrograms per kilogram (μg/kg) to 1.16 μg/kg, with the highest concentration reported 

at AOI01-01. PFOS was detected at all four surface soil locations, at concentrations ranging 

between 0.085 J μg/kg to 0.357 J μg/kg, with the highest concentration reported at AOI01-01. 

PFHxS was detected at one surface soil location (AOI01-01), at a concentration of 0.357 J μg/kg.

PFNA was detected at all four surface soil locations, at concentrations ranging between 

0.026 J μg/kg to 0.289 μg/kg, with the highest concentration reported at AOI01-01. No detected 

compound exceeded their respective SLs.

In the shallow subsurface soil, PFOA, PFBS, and PFNA were not detected. PFOS was detected 

at one of two locations (AVCRAD-MW001), at a concentration of 0.075 J μg/kg. PFHxS was 

detected at one of two locations (AVCRAD-MW001), at a concentration of 0.032 J μg/kg.

6.3.2 AOI 1 Groundwater Analytical Results 

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

summarizes the groundwater results. 
Site Inspection Report

Fresno AVCRAD, Fresno, California

AECOM 6-3

Within AOI 1, groundwater was sampled from one newly installed permanent monitoring well, 

AVCRAD-MW001, which was installed in June 2021. Groundwater was sampled in September 

2021. PFOA and PFNA were not detected at AVCRAD-MW001. PFOS was detected below the 

SL of 4 ng/L, at a concentration of 1.14 J ng/L. PFBS was detected below the SL of 601 ng/L at a 

concentration of 1.39 J ng/L. PFHxS was detected below the SL of 39 ng/L, at a concentration of 

1.96 ng/L. 

6.3.3 AOI 1 Conclusions

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

respective SLs. PFBS was not detected in soil. PFOS, PFBS, and PFHxS were detected in 

groundwater at concentrations below their respective SLs. PFOA and PFNA were not detected in 

groundwater. Therefore, no further evaluation at AOI 1 is warranted at this time. 

6.4 AOI 2 

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

AOI 2, which includes two potential release areas: Wash Rack and East Airfield Taxiway. The 

results in soil and groundwater are summarized on Table 6-2 through Table 6-5. 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 

6-4 summarize the soil results.

At AOI 2, soil was sampled from surface soil (0 to 2 feet bgs), shallow subsurface soil (13 to 15 

feet bgs), and deep subsurface soil (124 to 125 feet bgs) from boring location AVCRAD-MW002. 

Soil was also sampled from the surface (0 to 2 feet bgs) at locations AOI02-01, AOI02-02, and 

AOI02-03. In the shallow and deep subsurface soil, PFOA, PFOS, PFBS, PFHxS, and PFNA were 

not detected.

In the surface soil, PFOA was detected in all three locations, at concentrations ranging between 

0.089 J μg/kg to 0.270 J μg/kg, with the highest concentration reported at AOI02-01. PFOS was 

detected at all three surface soil locations, at concentrations ranging between 0.238 J μg/kg to 

0.424 J μg/kg, with the highest concentration reported at AOI02-02. PFBS was detected in two of 

the three surface soil locations at concentrations of 0.027 J μg/kg and 0.192 J μg/kg, with the 

highest concentration reported at AOI02-01. PFHxS was detected at one surface soil location 

(AOI02-01), at a concentration of 0.985 J μg/kg. PFNA was detected at all three surface soil 

locations, at concentrations ranging between 0.058 J μg/kg to 0.274 J μg/kg, with the highest 

concentration detected at AOI02-01. No detected compound exceeded their respective SLs.

6.4.2 AOI 2 Groundwater Analytical Results 

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

summarizes the groundwater results. 

Within AOI 2, groundwater was sampled from one newly installed permanent monitoring well, 

AVCRAD-MW002R, which was installed in August 2021. Groundwater was sampled in September 

2021. PFBS, PFHxS, and PFNA were not detected at AVCRAD-MW002R. PFOA was detected 

below the SL of 6 ng/L, at a concentration of 0.843 J ng/L. PFOS was detected below the SL of 4 

ng/L, at a concentration of 3.00 J ng/L.
Site Inspection Report

Fresno AVCRAD, Fresno, California

AECOM 6-4

6.4.3 AOI 2 Conclusions

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

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

the SLs. PFBS, PFHxS, and PFNA were not detected in groundwater. Therefore, further 

evaluation at AOI 2 is not warranted at this time. 

6.5 AOI 3 

This section presents the analytical results for soil in comparison to SLs for AOI 3, which includes 

one potential release area: the Corrosion Control Facility. No wells were installed at AOI 3; thus, 

groundwater was not sampled. The results in soil are presented in Table 6-2. Soil results are 

presented on Figure 6-1 through Figure 6-5. 

6.5.1 AOI 3 Soil Analytical Results

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

soil results. 

Soil was sampled from surface soil (0 to 2 feet bgs) from one hand auger boring location, AOI03-

01. At this location, PFOA was detected at a concentration of 1.11 μg/kg; PFOS was detected at

a concentration of 8.18 μg/kg; PFBS was detected at a concentration of 0.089 J μg/kg; PFHxS

was detected at a concentration of 3.43 μg/kg; and PFNA was detected at a concentration of

0.479 μg/kg. No detected compound exceeded their respective SL.

6.5.2 AOI 3 Conclusions

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

concentrations below their respective SLs. Groundwater was not sampled at AOI 3. Based on the 

results of the soil samples, further evaluation at AOI 3 is not warranted at this time. 
Table 6-2

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

Site Inspection Report, Fresno AVCRAD

Analyte OSD Screening 

Level a

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

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

PFBS 1900 ND U ND UJ ND UJ ND UJ ND UJ 0.192 J 0.027 J ND U

PFHxS 130 0.084 J ND UJ ND UJ ND UJ ND UJ 0.985 J ND UJ ND U

PFNA 19 0.289 J 0.136 J 0.134 J 0.026 J 0.028 J 0.274 J 0.075 J 0.058 J

PFOA 19 1.16 0.269 J 0.281 J ND UJ ND UJ 0.270 J 0.089 J 0.169 J

PFOS 13 0.357 J ND UJ 0.085 J 0.235 J 0.250 J 0.351 J 0.424 J 0.238 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 AOI Area of Interest

U = The analyte was not detected at a level greater than or equal to the adjusted DL AVCRAD Aviation Classification Repair Activity Depot

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

ft feet

HQ hazard quotient

ID identification

LCMSMS liquid chromatography with tandem mass spectrometry

LOD limit of detection

ND analyte not detected above the LOD

OSD Office of the Secretary of Defense

QSM Quality Systems Manual

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.

AOI01 AOI02

AOI02-03-SB-00-02

06/18/2021

0-2 ft

AOI02-01-SB-00-02

06/18/2021

0-2 ft

AOI02-02-SB-00-02

06/17/2021

0-2 ft

AVCRAD-MW001-SB-00-02

06/17/2021

0-2 ft

AVCRAD-MW001-SB-00-02D

06/17/2021

0-2 ft

AOI01-02-SB-00-02

06/17/2021

0-2 ft

AOI01-02-SB-00-02D

06/17/2021

0-2 ft

Area of Interest

Sample ID

Sample Date

Depth

AOI01-01-SB-00-02

06/18/2021

0-2 ft

AECOM 6-5
Table 6-2

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

Site Inspection Report, Fresno AVCRAD

Analyte OSD Screening 

Level a

Result Qual Result Qual

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

PFBS 1900 ND UJ 0.089 J

PFHxS 130 ND UJ 3.43

PFNA 19 0.025 J 0.479 J

PFOA 19 ND UJ 1.11

PFOS 13 0.097 J 8.18

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 AOI Area of Interest

U = The analyte was not detected at a level greater than or equal to the adjusted DL AVCRAD Aviation Classification Repair Activity Depot

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

ft feet

HQ hazard quotient

ID identification

LCMSMS liquid chromatography with tandem mass spectrometry

LOD limit of detection

ND analyte not detected above the LOD

OSD Office of the Secretary of Defense

QSM Quality Systems Manual

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

0-2 ft 0-2 ft

06/15/2021 06/18/2021

Depth

AVCRAD-MW002-SB-00-02 AOI03-01-SB-00-02

Sample Date

Area of Interest AOI03

Sample ID

AECOM 6-6
Table 6-3

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

Site Inspection Report, Fresno AVCRAD

Analyte OSD Screening 

Level a

Result Qual Result Qual

PFBS 25000 ND U ND UJ

PFHxS 1600 0.032 J ND UJPFNA 250 ND U ND UJ

PFOA 250 ND U ND UJPFOS 160 0.075 J ND UJ

Grey Fill Detected concentration exceeded OSD Screening Levels Ch

PF

References PF

PFPFPF

Interpreted Qualifiers Ac

J = Estimated concentration AOU = The analyte was not detected at a level greater than or equal to the adjusted DL AVUJ = 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. DL 

ft HQ ID LCLOND OSQSQuSB USμg

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.

AOI02

AVCRAD-MW002-SB-13-15

06/15/2021

13-15 ft

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

Area of Interest

Sample ID

Sample Date

Depth

AOI01

AVCRAD-MW001-SB-13-15

06/17/2021

13-15 ft

AECOM 
Table 6-4

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

Site Inspection Report, Fresno AVCRAD

Area of Interest

Sample ID

Sample Date

Depth

Analyte Result Qual Result Qual

PFBS ND U ND UJ

PFHxS ND U ND UJ

PFNA ND U ND UJ

PFOA ND U ND UJ

PFOS ND U ND UJ

Interpreted Qualifiers Chemical AbbreviatioU = The analyte was not detected at a level greater than or equal to the adjusted DL PFBS 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. PFHxS 

PFNA PFOA PFOS Acronyms and Abbrev

AOI AVCRAD DL ft ID LCMSMS LOD ND QSM Qual SB μg/kg 

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

AOI01

AVCRAD-MW001-SB-124-125

06/21/2021

124-125 ft

AOI02

AVCRAD-MW002-SB-124-125

06/16/2021

124-125 ft

AECOM 
Table 6-5

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

Site Inspection Report, Fresno AVCRAD

Analyte OSD Screening 

Level a

Result Qual Result Qual

PFBS 601 1.39 J ND UPFHxS 39 1.96 J ND U

PFNA 6 ND U ND UPFOA 6 ND U 0.843 JPFOS 4 1.14 J 3.00 J

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviatio

PFBS 

References PFHxS 

PFNA PFOA PFOS 

Interpreted Qualifiers Acronyms and Abbre

J = Estimated concentration AOI U = The analyte was not detected at a level greater than or equal to the adjusted DL AVCRAD 

DL GW HQ ID LCMSMS LOD ND OSD QSM Qual USEPA ng/l 

AOI02

AVCRAD-MW002-GW

09/14/2021

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.

Area of Interest

Sample ID

Sample Date

AOI01

AVCRAD-MW001-GW

09/14/2021

AECOM 
Site Inspection Report

Fresno AVCRAD, Fresno, California

AECOM 6-10

THIS PAGE INTENTIONALLY BLANK
AVCRAD-MW001

AVCRAD-MW002

AVCRAD-MW001

AVCRAD-MW002

AVCRAD-MW001

AVCRAD-MW002

AOI01-01

AOI01-02

AOI02-02

AOI02-01

AOI02-03

AOI03-01

PROJECT

0 170 340 680

Feet

Figure 6-1

PFOA Detections in Soil

12420 Milestone Center Drive ­ Germantown, MD 20876

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Fresno AVCRAD, CA

8/25/2022

8/25/2022

8/25/2022

MS

EB

CM

GIS BY

CHK BY

PM

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

8/25/2022

1:4,080

Legend

Facility Boundary

Shallow Intermediate Deep

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

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

PFOA Results (μg/Kg)

ND

>ND - 19

>19 - 250

>250 - 2,500

>2,500

AECOM 6-11
AVCRAD-MW001

AVCRAD-MW002

AVCRAD-MW001

AVCRAD-MW002

AVCRAD-MW001

AVCRAD-MW002

AOI01-01

AOI01-02

AOI02-02

AOI02-01

AOI02-03

AOI03-01

PROJECT

0 170 340 680

Feet

Figure 6-2

PFOS Detections in Soil

12420 Milestone Center Drive ­ Germantown, MD 20876

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Fresno AVCRAD, CA

8/25/2022

8/25/2022

8/25/2022

MS

EB

CM

GIS BY

CHK BY

PM

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

8/25/2022

1:4,080

Legend

Facility Boundary

Shallow Intermediate Deep

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 6-12
AVCRAD-MW001

AVCRAD-MW002

AVCRAD-MW001

AVCRAD-MW002

AVCRAD-MW001

AVCRAD-MW002

AOI01-01

AOI01-02 AOI02-02

AOI02-01

AOI02-03

AOI03-01

PROJECT

0 170 340 680

Feet

Figure 6-3

PFBS Detections in Soil

12420 Milestone Center Drive ­ Germantown, MD 20876

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Fresno AVCRAD, CA

8/25/2022

8/25/2022

8/25/2022

MS

EB

CM

GIS BY

CHK BY

PM

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

8/25/2022

1:4,080

Legend

Facility Boundary

Shallow Intermediate Deep

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 6-13
AVCRAD-MW001

AVCRAD-MW002

AVCRAD-MW001

AVCRAD-MW002

AVCRAD-MW001

AVCRAD-MW002

AOI01-01

AOI01-02 AOI02-02

AOI02-01

AOI02-03

AOI03-01

PROJECT

0 170 340 680

Feet

Figure 6-4

PFHxS Detections in Soil

12420 Milestone Center Drive ­ Germantown, MD 20876

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Fresno AVCRAD, CA

8/25/2022

8/25/2022

8/25/2022

MS

EB

CM

GIS BY

CHK BY

PM

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

8/25/2022

1:4,080

Legend

Facility Boundary

Shallow Intermediate Deep

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 6-14
AVCRAD-MW001

AVCRAD-MW002

AVCRAD-MW001

AVCRAD-MW002

AVCRAD-MW001

AVCRAD-MW002

AOI01-01

AOI01-02

AOI02-02

AOI02-01

AOI02-03

AOI03-01

PROJECT

0 170 340 680

Feet

Figure 6-5

PFNA Detections in Soil

12420 Milestone Center Drive ­ Germantown, MD 20876

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Fresno AVCRAD, CA

8/25/2022

8/25/2022

8/25/2022

MS

EB

CM

GIS BY

CHK BY

PM

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

8/25/2022

1:4,080

Legend

Facility Boundary

Shallow Intermediate Deep

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 6-15
AVCRAD-MW001

AVCRAD-MW002R

AVCRAD-MW001

AVCRAD-MW002R

AVCRAD-MW001

AVCRAD-MW002R

PFOA Results (ng/L)

ND

>ND - 6

>6 - 40

>40 - 70

>70

PROJECT

0 170 340 680

Feet

Figure 6-6

PFOA, PFOS, and PFBS Detections in Groundwater

12420 Milestone Center Drive ­ Germantown, MD 20876

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Fresno AVCRAD, CA

10/13/2022

10/13/2022

10/13/2022

MS

EB

CM

GIS BY

CHK BY

PM

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

10/13/2022

1:4,080

Legend

Facility Boundary

Inferred Groundwater Flow Direction

PFOA PFOS PFBS

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

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 6-16
AVCRAD-MW001

AVCRAD-MW002R

AVCRAD-MW001

AVCRAD-MW002R

PFHxS Results (ng/L)

ND

>ND - 39

>39 - 100

>100 - 1,000

>1,000

PROJECT

0 170 340 680

Feet

Figure 6-7

PFHxS and PFNA Detections in Groundwater

12420 Milestone Center Drive ­ Germantown, MD 20876

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Fresno AVCRAD, CA

8/10/2022

8/10/2022

8/10/2022

MS

EB

CM

GIS BY

CHK BY

PM

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

8/10/2022

1:4,080

Legend

Facility Boundary

Inferred Groundwater Flow Direction

PFHxS PFNA

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

PFNA Results (ng/L)

ND

>ND - 6

>6 - 100

>100 - 1,000

>1,000

AECOM 6-17
Site Inspection Report

Fresno AVCRAD, Fresno, California

AECOM 6-18

THIS PAGE INTENTIONALLY BLANK
Site Inspection Report

Fresno AVCRAD, Fresno, California

AECOM 7-1

7. Exposure Pathways

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

Figure 7-3. Please note that while the CSM discussion assists in determining if a receptor may 

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

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

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

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

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

potentially complete when the following conditions are present:

1. Contaminant source;

2. Environmental fate and transport;

3. Exposure point;

4. Exposure route; and

5. Potentially exposed populations.

If any of these elements are missing, the pathway is incomplete. The CSM figures use an empty 

circle symbol to represent an incomplete exposure pathway. Areas with an incomplete pathway 

generally warrant no further action. However, the pathway is considered potentially complete if the 

relevant compounds are detected, in which case the CSM figure uses a half-filled circle symbol to 

represent a potentially complete exposure pathway. Additionally, a completely filled circle symbol is 

used to indicate when a potentially complete exposure pathway has detections of relevant 

compounds above the SLs. Areas with an identified potentially complete pathway that have 

detections of the relevant compounds above the SLs may warrant further investigation. Although 

the CSMs indicate whether potentially complete exposure pathways may exist, the 

recommendation for future study in a RI or no action at this time is based on the comparison of 

the SI analytical results for the relevant compounds to the SLs.

In general, the potential routes of exposure to the relevant compounds are ingestion and 

inhalation. Human exposure via the dermal contact pathway may occur, and current risk practice 

suggests it is an insignificant pathway compared to ingestion; however, exposure data for dermal 

pathways are sparse and continue to be the subject of toxicological study. The receptors 

evaluated are consistent with those listed in USEPA guidance for risk screening (USEPA, 2001). 

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

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

boundary, and recreational users outside of the facility boundary. 

7.1 Soil Exposure Pathway

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

between the source and potential receptors at AOI 1, AOI 2, and AOI 3 based on the 

aforementioned criteria. 

7.1.1 AOI 1 

From approximately 2008 to 2011, and in 2014, controlled AFFF releases occurred annually 

during fire training activities. At AOI 1, PFOA, PFOS, PFHxS, and PFNA were detected in surface

soil, and PFOS and PFHxS were detected in the shallow subsurface soil at AOI 1. 
Site Inspection Report

Fresno AVCRAD, Fresno, California

AECOM 7-2

Active construction was observed at the facility during the SI. Site workers and construction 

workers could contact constituents in surface soil via incidental ingestion and inhalation of dust; 

therefore, the soil exposure pathway for those receptors is considered potentially complete. 

Current and future construction workers could contact constituents in subsurface soil via 

incidental ingestion; therefore, the soil exposure pathway for this receptor is considered potentially 

complete. Additionally, off-facility residents and recreational users may potentially be exposed to 

these constituents via inhalation of dust caused by on-facility ground disturbing activities. The 

CSM for AOI 1 is presented on Figure 7-1. 

7.1.2 AOI 2

From 2007 to 2010, AFFF was periodically released to the Wash Rack. AOI 2 also includes the 

East Airfield Taxiway, where AFFF was released in 2015 during the servicing of Tri-MaxTM fire 

extinguishers. PFOA, PFOS, PFBS, PFHxS, and PFNA were detected in the surface soil at AOI 

2. 

Active construction was observed at the facility during the SI. Site workers and construction 

workers could contact constituents in surface soil via incidental ingestion and inhalation of dust; 

therefore, the soil exposure pathway for those receptors is considered potentially complete. 

Constituents were not detected in the shallow subsurface soil; therefore, the soil exposure 

pathway for this receptor is considered incomplete. Additionally, off-facility residents and 

recreational users may potentially be exposed to these constituents via inhalation of dust caused 

by on-facility ground disturbing activities. The CSM for AOI 2 is presented on Figure 7-2. 

7.1.3 AOI 3

The Corrosion Control Facility contains an AFFF fire suppression system with a 1,100-gallon 

capacity AFFF tank, containing 3% AFFF. A small drip leak at fire suppression system was 

reported approximately six to eight months after the system installation in June 2011. Only surface 

soil was sampled at AOI 3. PFOA, PFOS, PFBS, PFHxS, and PFNA were detected in the surface 

soil at this AOI. 

Site workers and construction workers could contact constituents in surface soil via incidental 

ingestion and inhalation of dust; therefore, the soil exposure pathway for those receptors is 

considered potentially complete. Current and future construction workers could contact 

constituents in subsurface soil via incidental ingestion; therefore, the soil exposure pathway for 

this receptor is considered potentially complete. Additionally, off-facility residents and recreational 

users may potentially be exposed to these constituents via inhalation of dust caused by on-facility 

ground disturbing activities. The CSM for AOI 3 is presented on Figure 7-3.

7.2 Groundwater Exposure Pathway

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

exists at AOI 1 and AOI 2 between the source and potential receptors based on the 

aforementioned criteria.

7.2.1 AOI 1

PFOS, PFBS, and PFHxS were detected at concentrations below their respective SLs in the one 

permanent monitoring well sampled at AOI 1. Municipal drinking water wells exist within one mile 

northwest of the facility boundary, therefore, the ingestion exposure pathway for site workers and 

off-facility residents is considered potentially complete. Depths to water measured in November 

2021 during the SI ranged from 124.46 to 124.96 feet bgs. Construction activities were observed 

to be occurring near the facility’s northern boundary at the time of the SI field work. However, 
Site Inspection Report

Fresno AVCRAD, Fresno, California

AECOM 7-3

groundwater at the potential source area exceeds 120 feet bgs; therefore, a construction worker 

during trenching activities would not reasonably come into contact with groundwater, and the 

exposure pathway is considered incomplete. The CSM for AOI 1 is presented on Figure 7-1

7.2.2 AOI 2 

PFOA and PFOS were detected at concentrations below their respective SLs in the one 

permanent monitoring well sampled at AOI 2. Municipal drinking water wells exist within one mile 

of the facility boundary, therefore, the ingestion exposure pathway for site workers and off-facility 

residents is considered potentially complete. The inferred groundwater flow direction is to the 

east; however, at the time of synoptic gauging of the two wells installed during the SI, groundwater 

flow was inferred to be to the northwest. Construction activities were observed to be occurring 

near the facility’s northern boundary at the time of the SI field work. Groundwater at the potential 

source area exceeds 120 feet bgs; therefore, a construction worker during trenching activities 

would not reasonably come into contact with groundwater, and the exposure pathway is 

considered 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.

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

the AOIs, it is possible that those compounds may have migrated from soil and groundwater via 

surface water runoff to the Fresno Yosemite International Airport drainage system which flows into 

Mills Creek and feeds into Herndon Canal. Therefore, the surface water and sediment ingestion 

exposure pathway for the off-facility recreational user is considered potentially complete. The 

Herndon Canal is a tributary to the San Joaquin River, which eventually discharges into the San 

Francisco Bay (HazCon, 2017). The CSMs for AOI 1, AOI 2, and AOI 3 are presented on Figure 

7-1, 7-2, and 7-3, respectively.
Site Inspection Report

Fresno AVCRAD, Fresno, California

AECOM 7-4

THIS PAGE INTENTIONALLY BLANK
Media

SOURCE PATHWAY RECEPTOR

AOI 1

Historical Fire 

Training

Activities

Subsurface

Soil

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

Fresno AVCRAD, California

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

Surface

Water

Surface

Water Flow

NOTES

1. The resident and recreational users

refer to off-site receptors.

2. Human consumption of fish

potentially affected by PFAS is possible.

3. Active construction within AOI 1 was

observed at the facility during SI field

work.

4. Groundwater was encountered at

depths greater than 120 feet below

ground surface at AOI 1.

Site 

Worker

Construction 

Worker3,4 Resident1 Recreational User1,2

Surface Soil /

/ / / /

Site 

Worker

Construction 

Worker3,4 Resident1 Recreational

User1,2

AECOM 7-5
Media

SOURCE PATHWAY RECEPTOR

AOI 2

AFFF Storage

in Hazmat 

Locker and

Mobile Fire

Extinguisher

Discharge

Surface Soil

Subsurface

Soil

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 7-2

Conceptual Site Model, AOI 2

Fresno AVCRAD, California

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

Surface

Water

Surface

Water Flow

NOTES

1. The resident and recreational users

refer to off-site receptors.

2. Human consumption of fish

potentially affected by PFAS is possible.

3. Active construction within AOI 1 was

observed at the facility during SI field

work.

4. Groundwater was encountered at

depths greater than 120 feet below

ground surface at AOI 2.

Site 

Worker

Construction 

Worker3,4 Resident1

/

Recreational 

User1,2

/ / / /

Site 

Worker

Construction 

Worker3,4 Resident1 Recreational

User1,2

/ / / /

AECOM 7-6
Media

SOURCE PATHWAY RECEPTOR

AOI 3

AFFF Fire 

Suppression

System

PFAS in

Surface Soil

PFAS in

Subsurface

Soil

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 7-3

Conceptual Site Model, AOI 3

Fresno AVCRAD, California

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

PFAS in

Surface

Water

Surface

Water Flow

NOTES

1. The resident and recreational users

refer to off-site receptors.

2. Human consumption of fish

potentially affected by PFAS is possible.

3. Active construction within AOI 1 was

observed at the facility during SI field

work.

4. Shallow subsurface soil, deep

subsurface soil, and grab groundwater

samples were not collected at AOI 3.

Site 

Worker Resident1

/

Recreational 

User1,2

Site 

Worker

Construction 

Worker3

Resident1 Recreational

User1,2

/ / / /

Construction 

Worker3

AECOM 7-7
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AECOM 7-8

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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 in multiple mobilizations, from 15 to 24 June and between 17 

August and 14 September 2021 and February 2022 and consisted of utility clearance, sonic drilling, 

soil sample collection, permanent monitoring well installation, monitoring well development, 

groundwater sample collection, and land surveying. Field activities were conducted in accordance 

with the SI QAPP Addendum (AECOM, 2021a), except as previously noted in Section 5.8. 

To fulfill the project DQOs set forth in the approved SI QAPP Addendum (AECOM, 2021a), samples 

were collected and analyzed for a subset of 18 compounds by LC/MS/MS compliant with QSM 5.3 

Table B-15 as follows. 

• Twelve (12) soil samples from two (2) boring locations and six (6) surface soil locations;

• Two grab groundwater samples from two (2) newly installed permanent wells;

• Eleven (11) 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, no further evaluation under CERCLA is warranted for each of the 

three AOIs at this time (see Table 8-1). Based on the CSMs developed and revised in light of the 

SI findings, there is potential for exposure to 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 against 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, PFHxS, and PFNA in soil at AOI 1

were below their respective SLs. PFBS was not detected in the soil.

• The detected concentrations of PFOS, PFBS, and PFHxS in groundwater were

below their respective SLs. PFOA and PFNA were not detected in the groundwater.

• Based on the results of the SI, no further evaluation of AOI 1 is warranted at this time.

• At AOI 2:
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Fresno AVCRAD, Fresno, California

AECOM 8-2

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

AOI 2 were below their respective SLs. 

• The detected concentrations of PFOA and PFOS in groundwater were below their 

respective SLs. PFBS, PFHxS, and PFNA were not detected in the groundwater.

• Based on the results of the SI, no further evaluation of AOI 2 is warranted at this time. 

• At AOI 3: 

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

AOI 3 were below their respective SLs. 

• Based on the results of the SI, no further evaluation of AOI 3 is warranted at this time. 

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

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

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

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

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

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

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

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

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

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

AOI Potential 

Release Area

Soil – 

Source 

Area

Groundwater – 

Source Area

Groundwater 

– 

Facility 

Boundary

Future Action

1 Hangar Training 

Area N/A

No further 

action at this 

time

2 Wash Rack and East 

Airfield Taxiway N/A

No further 

action at this 

time

3 Corrosion Control 

Facility N/A N/A

No further 

action at this 

time

Legend:

= detected; exceedance of the screening levels

= detected; no exceedance of the screening levels

= not detected
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Fresno AVCRAD, Fresno, California

AECOM 8-3

8.3 Uncertainties

Table 8-2 summarized the uncertainties and data gaps associated with this SI. Based on these 

uncertainties, further investigation may be warranted in a Supplemental SI. 

Table 8-2: Summary of Site Inspection Uncertainties

AOI Potential 

Release Area

Source of Uncertainty

1-3 All

Soil sampling was limited due to impervious surfaces immediately 

beneath and surrounding the suspected source areas. Therefore, the 

presence or absence of relevant compounds above the SLs at 

locations not sampled is unknown. 

No soil sampling deeper than surficial soil samples were collected 

directly beneath the AOIs. Therefore, leaching of PFAS constituents 

from surface soil to subsurface soil and groundwater is unknown. 

1-3 All

The groundwater investigation was limited to two wells. As a result, a 

site-specific hydraulic gradient could not be established and the 

inferred groundwater flow direction is uncertain. Additionally, no 

groundwater sampling was conducted at AOI 3. Based on the inferred 

groundwater flow direction, the groundwater samples collected during 

the SI were not located downgradient of the AOIs for which they were 

intended. 

3 Corrosion Control 

Facility

No groundwater sampling was conducted at AOI 3. Therefore, the 

groundwater exposure pathway and the presence or absence of 

relevant compounds in groundwater are unknown at AOI 3. 
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AECOM 9-1

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