FINAL

Site Inspection Report

Reno Army Aviation Support Facility

Reno, Nevada

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

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

Oxide Dimer Acid (HFPO-DA), and Perfluorobutanesulfonic Acid (PFBS)

ARNG Installations, Nationwide

December 2023

Prepared for:

Army National Guard Headquarters

111 S. George Mason Drive

Arlington, VA 22204

UNCLASSIFIED
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TABLE OF CONTENTS

Page

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

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

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

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

EXECUTIVE SUMMARY .........................................................................................................1

1. INTRODUCTION ........................................................................................... 1-1

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

1.2 Site Inspection Purpose......................................................................... 1-1

2. FACILITY BACKGROUND........................................................................... 2-1

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

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

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

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

2.2.3 Hydrology.............................................................................. 2-3

2.2.4 Climate .................................................................................. 2-4

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

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

2.3 History of PFAS Use ............................................................................ 2-5

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

3.1 AOI 1 – Former Firetruck Bay and Rotary Wing Parking Area ............. 3-1

3.2 AOI 2 – Stockpiled Soils...................................................................... 3-1

3.3 Adjacent Sources.................................................................................. 3-2

3.3.1 Reno-Stead Airport ................................................................ 3-2

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

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

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

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

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

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

5. SITE INSPECTION ACTIVITIES................................................................... 5-1
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5.1 Pre-Investigation Activities .................................................................. 5-2

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

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

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

5.2 Soil Borings and Soil Sampling ............................................................ 5-3

5.3 Temporary Well Installation and Groundwater Sampling...................... 5-4

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

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

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

5.7 Laboratory Analytical Methods ............................................................ 5-6

5.8 Deviations from SI UFP-QAPP Addendum .......................................... 5-6

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

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

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

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

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

6.3.2 Groundwater Analytical Results............................................. 6-3

6.3.3 Conclusions ........................................................................... 6-3

6.4 AOI 2 ................................................................................................... 6-4

6.4.1 Soil Analytical Results........................................................... 6-4

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

6.4.3 Conclusions ........................................................................... 6-4

6.5 BOUNDARY SAMPLE LOCATIONS ................................................ 6-4

6.5.1 Boundary Sample Locations – Soil Analytical Results ........... 6-5

6.5.2 Boundary Sample Locations – Groundwater Analytical Results6-

5

6.5.3 Conclusions ........................................................................... 6-5

7. EXPOSURE PATHWAYS .............................................................................. 7-1

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

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

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

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

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

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

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

Appendix A. Data Validation Reports

Appendix B. Field Documentation

B1. Log of Daily Notice of Field Activities

B2. Sampling Forms

B3. Survey Data

B4. Field Change Request Form

B5. Investigative Derived Waste Placement Location

Appendix C. Photographic Log

Appendix D. Technical Project Planning Meeting Minutes

Appendix E. Boring Logs and Well Construction Diagrams

Appendix F. Analytical Results

Appendix G. Laboratory Reports
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LIST OF FIGURES

Figure 2-1 Facility Location

Figure 2-2 Facility Topography

Figure 2-3 Groundwater Features

Figure 2-4 Groundwater Elevations, July 2022

Figure 2-5 Surface Water Features

Figure 3-1 Areas of Interest

Figure 5-1 Site Inspection Sample Locations

Figure 6-1 PFOS Detections in Soil

Figure 6-2 PFOA Detections in Soil

Figure 6-3 PFBS Detections in Soil

Figure 6-4 PFHxS Detections in Soil

Figure 6-5 PFNA Detections in Soil

Figure 6-6 PFOS, PFOA, 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
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LIST OF TABLES

Table ES-1 Screening Levels (Soil and Groundwater)

Table ES-2 Summary of Site Inspection Findings and Recommendations

Table 5-1 Samples by Medium, Reno AASF, Reno, Site Inspection Report

Table 5-2 Soil Boring Depths and Temporary Well Screen Intervals, Reno AASF, Reno, 

Site Inspection Report

Table 5-3 Groundwater Elevation, Reno AASF, Reno, Site Inspection Report

Table 6-1 Screening Levels (Soil and Groundwater)

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

Report, Reno AASF

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

Inspection Report, Reno AASF

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

Inspection Report, Reno AASF

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

Report, Reno AASF

Table 8-1 Summary of Site Inspection Findings and Recommendations
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LIST OF ACRONYMS AND ABBREVIATIONS

°C Degrees Celsius

% Percent

μg/kg Microgram(s) per kilogram

g/L Microgram(s) per liter

AASF Army Aviation Support Facility

AECOM AECOM Technical Services, Inc.

AFFF Aqueous Film-Forming Foam

amsl Above mean sea level

ANG Air National Guard

AOI Area of Interest

ARNG Army National Guard

ASTM American Society for Testing and Materials

bgs Below ground surface

blvd Boulevard

bmsl Below mean sea level

btoc Below top of casing

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act

COC Chain-of-custody

CSM Conceptual site model

DA Department of the Army

DoD Department of Defense

DOE Department of Energy

DOT Department of Transportation

DPT Direct-push technology

DQI Data quality indicator

DQO Data quality objective

DUA Data Usability Assessment

EA EA Engineering, Science, and Technology, Inc., PBC

EIS Extraction internal standards

ELAP Environmental Laboratory Accreditation Program

EM Engineer Manual

EB Equipment Blank

EDRTM Environmental Data Resources

EPA Environmental Protection Agency

FB Field blank

FedEx Federal Express

ft Foot (feet)

ft/ft foot per foot

FMS Field Maintenance Shop
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GIS Geographic information system

GPR Ground-penetrating radar

HAZMAT Hazardous Material

HDPE High-density polyethylene

HFPO-DA Hexafluoropropylene oxide dimer acid

HQ Hazard Quotient

HSA Hollow Stem Auger

IDW Investigation-derived waste

ITRC Interstate Technology Regulatory Council

LC/MS/MS Liquid chromatography tandem mass spectrometry

LCS Laboratory control sample

LCSD Laboratory control sample duplicate

MS Matrix spike

MSD Matrix spike duplicate

NDEP Nevada Division of Environmental Protection

NELAP National Environmental Laboratory Accreditation Program

ng/L Nanogram(s) per liter

No. Number

NOI Notice of intent

NVARNG Nevada Army National Guard

NVDWR Nevada Division of Water Resources

OSD Office of the Secretary of Defense

PA preliminary assessment

PFAS per- and polyfluoroalkyl substances

PFBA Perfluorobutanoic acid

PFBS perfluorobutanesulfonic acid

PFHxA Perfluorohexanoic Acid

PFTeDA perfluorotetradecanoic acid

PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

PFUnA perfluoroundecanoic acid

PID photoionization detector

PVC polyvinyl chloride

QA Quality assurance

QAPP Quality Assurance Project Plan

QC Quality control

QSM Quality Systems Manual
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RC Readiness Center

Rd Road

RI Remedial investigation

RPD Relative percent difference

RTAA Reno-Tahoe Airport Authority

SI Site Inspection

SL Screening level

SWPPP Storm Water Pollution Prevention Plan

TCRA Time Critical Removal Action

TMWA Truckee Meadows Water Authority

TOC Total organic carbon

TPP Technical Project Planning

UFP Uniform Federal Policy

USACE U.S. Army Corps of Engineers

USEPA U.S. Environmental Protection Agency

USFWS U.S. Fish and Wildlife Service

USGS U.S. Geological Survey

W West

Wood Wood Environment & Infrastructure Solutions, Inc.

WSP WSP USA Environment & Infrastructure, Inc.
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EXECUTIVE SUMMARY

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

Inspections (SIs) at ARNG facilities nationwide based on the current or potential historical use of 

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

memorandum regarding Investigating Per- and Polyfluoroalkyl Substances within the 

Department of Defense Cleanup Program (Assistant Secretary of Defense, 2022) from the Office 

of the Secretary of Defense (OSD) dated 6 July 2022. The six compounds listed in the OSD 

memorandum include perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), 

perfluorobutanesulfonic acid (PFBS), perfluorononanoic acid (PFNA), perfluorohexanesulfonic 

acid (PFHxS), and hexafluoropropylene oxide dimer acid (HFPO-DA)1. These compounds are 

collectively referred to as “relevant compounds” throughout the document and the applicable 

screening levels (SLs) are provided below in Table ES-1.

The PA identified one Area of Interest (AOI) and a second AOI was identified during the SI 

planning process. The AOIs are where PFAS-containing materials may have been used, stored, 

disposed, or released historically (see Table ES-2 for the AOI locations). The objective of the SI 

was to identify whether there has been a release to the environment from the AOIs and determine

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

threats, or no further action is required based on a comparison of SI results to SLs for the 

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

(AASF) in Reno, Nevada and determined further investigation is warranted for AOI 1: Former 

Firetruck Bay and Rotary Wing Parking Area and no further action is warranted for AOI 2: 

Stockpiled Soils. The Reno AASF will also be referred to as the “Facility” throughout this 

document.

The Facility, operated by the Nevada ARNG (NVARNG), encompasses approximately 63 acres 

in the southwest portion of Washoe County, Nevada, about 13 miles northwest of downtown 

Reno, and is directly adjacent to Reno-Stead Airport. The Facility and properties immediately 

surrounding the Reno AASF are owned by the Reno-Tahoe Airport Authority (RTAA), with 

Army Aviation Drive to the west, and Reno-Stead Airport to the south and east of the Facility.

NVARNG rented hangars and operated helicopters from 1972 to 1984 at the former Stead Air 

Force Base, which is now the Reno-Stead Airport. In 1984, the current Facility was constructed 

on land leased to the NVARNG by the RTAA and exists and operates as part of the Harry Reid 

Readiness Training Center. The Facility includes multiple buildings, parking lots, and a Rotary 

Wing Parking Apron (AECOM, 2020).

The PA identified one AOI for investigation during the SI phase and an additional AOI was 

added following SI scoping discussions. SI sampling results from the two AOIs were compared 

to OSD SLs. Table ES-2 summarizes the SI results for the AOIs. Based on the results of this SI, 

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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and following the Comprehensive Environmental Response, Compensation, and Liability Act 

(CERCLA) process, further evaluation is warranted in a Remedial Investigation (RI) for AOI 1, 

and no further action is warranted for AOI 2. 

Table ES-1. Screening Levels (Soil and Groundwater) 

Analyte,2

Residential 

(Soil) 

(μg/kg)1 

(0-2 feet bgs) 

Industrial / Commercial 

Composite Worker 

(Soil) 

(μg/kg) 1 

2-15 feet bgs) 

Tap Water 

(Groundwater) 

(ng/L) 1 

PFOA 19 250 6 

PFOS 13 160 4 

PFBS 1,900 25,000 601 

PFHxS 130 1,600 39 

PFNA 19 250 6 

Notes: 

1. Assistant Secretary of Defense. July 2022. Risk-Based Screening Levels in Groundwater 

and Soil using United States Environmental Protection Agency’s (USEPA’s) Regional 

Screening Level Calculator. Hazard Quotient (HQ)=0.1. May 2022. 

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

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

Based on the CSM developed during the PA and revised based on SI findings, the 

presence of HFPO-DA is not anticipated at the facility because HFPO-DA is generally 

not a component of MIL-SPEC AFFF and based on its history including distribution 

limitations that restricted use of GenX, it is generally not a component of other products 

the military used. In addition, it is unlikely that GenX would be an individual chemical of 

concern in the absence of other PFAS. 

g/kg = microgram(s) per kilogram 

bgs = below ground surface 

ng/L = nanogram(s) per liter

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

AOI

Potential Release 

Area

Soil – 

Source Area

Groundwater – 

Source Area

Groundwater – 

Facility Boundary Future Action 

1 

Former Firetruck Bay 

and Rotary Wing 

Parking Area

Proceed to 

Remedial 

Investigation 

2 Stockpiled Soils No further Action 

Legend:

 = Detected; exceedance of screening levels 

 = Detected; no exceedance of screening levels 

 = Not detected 

 
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1. INTRODUCTION

1.1 PROJECT AUTHORIZATION

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

Assessments (PAs) and Site Inspections (SIs) at ARNG facilities nationwide based on the current 

or potential historical use of per- and polyfluoroalkyl substances (PFAS) with a focus on the six 

compounds presented in the memorandum regarding Investigating Per- and Polyfluoroalkyl 

Substances within the Department of Defense Cleanup Program (Assistant Secretary of Defense, 

2022) from the Office of the Secretary of Defense (OSD) dated 6 July 2022. The six compounds 

listed in the OSD memorandum are referred to as “relevant compounds” throughout this 

document and include perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), 

perfluorobutanesulfonic acid (PFBS), perfluorononanoic acid (PFNA), perfluorohexanesulfonic 

acid (PFHxS), and hexafluoropropylene oxide dimer acid (HFPO-DA)1at ARNG facilities 

nationwide. The ARNG performed this SI at the Reno Army Aviation Support Facility (AASF) 

in Reno, Nevada. The Reno AASF is also referred to as the “Facility” throughout this report.

The SI project elements were performed in accordance with the Comprehensive Environmental 

Response, Compensation, and Liability Act (CERCLA) (U.S. Environmental Protection Agency 

[EPA] 1980), as amended, the National Oil and Hazardous Substances Pollution Contingency 

Plan (40 Code of Federal Regulations Part 300; EPA 1994), and in compliance with U.S. 

Department of Army (DA) requirements and guidance for field investigations.

1.2 SITE INSPECTION PURPOSE

A PA was performed at the Reno AASF (AECOM Technical Services, Inc. [AECOM] 2020) that

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

stored, disposed, or released historically, and a second AOI was identified during the SI planning 

process. 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 during the SI scoping 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

Reno AASF is located at the Harry Reid Readiness Training Center and occupies approximately 

63 acres in the southwest portion of Washoe County, Nevada, about 13 miles northwest of 

downtown Reno, and is directly adjacent to Reno-Stead Airport (Figure 2-1). The Facility and 

properties immediately surrounding the AASF are owned by the Reno-Tahoe Airport Authority 

(RTAA), with Army Aviation Drive to the west, and Reno-Stead Airport to the south and east of 

the Facility.

Nevada Army National Guard (NVARNG) rented hangars and operated helicopters from 1972 to 

1984 at the former Stead Air Force Base, which is now the Reno-Stead Airport. In 1984, the 

current Facility was constructed on land leased to the NVARNG by the RTAA and exists and 

operates as part of the Harry Reid Readiness Training Center. The Facility includes multiple 

buildings, parking lots, and a Rotary Wing Parking Apron that are used by NVARNG to store 

and maintain rotary aircraft, and to train and ensure the readiness of Facility personnel. The area 

is fenced and has controlled access (AECOM, 2020).

2.2 FACILITY ENVIRONMENTAL SETTING

Reno AASF is located in the southwestern portion of Washoe County, Nevada and is 

approximately 4,987 feet (ft) above mean sea level (amsl) (Figure 2-2). The approximate 

geographic coordinates for the center of the property are 39°40’22.10” N; 119°53’29.52” W. The 

majority of the Facility is developed with buildings, concrete, and asphalt features.

The Facility and neighboring City of Reno is located within the Truckee Meadows, which is a 

basin bounded by the Sierra Nevada on the western edge of the Great Basin. Truckee Meadows 

covers approximately 94 square miles in western Nevada and is bounded on the west by the 

Carson Range, on the east by the Virginia Range and Pine Nut Mountains, and on the south by 

the Steamboat Hills and Peavine Peak (AECOM, 2020).

2.2.1 Geology

Reno AASF is located in the northern portion of the Lemmon Valley. The primary structural 

indicators in the Lemmon Valley area are north-to-northeast-trending valleys between mountain 

ranges. A major fault in the area, the Airport fault, divides the valley into two structural areas. 

The fault also approximates the divide between two hydrologic subareas in the valley: the East 

Lemmon subarea is in the eastern section of the valley, and the Silver Lake subarea is to the 

west. The U.S. Geological Survey (USGS) describes the shallow geological deposits of this 

region as stratified sequences of quaternary alluvium (AECOM, 2020).

This alluvium consists of unconsolidated gravel, sand, silt, and clay deposits. During the SI, 

unconsolidated sediments at the Facility were dominated by poorly graded and silty sands with

interbedded layers of medium plastic fines (silt/clay) and clayey sands. The borings were 

completed at depths between 45 and 71 ft below ground surface (bgs).
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A sample for grain size analysis was collected at one location per AOI, AOI01-04 and AOI02-01

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

results for AOI 1 indicate that the soil samples are comprised primarily of sand (38.3%) and silt

(43%) with clay (16.6%). The results for AOI 2 indicate that the soil samples are comprised 

primarily of silt (49.5%) and clay (26.5%) with sand (23.9%). These results and Facility 

observations are consistent with the reported depositional environment of the region. The 

thickness of the alluvium is generally 200 to 400 ft before bedrock.

2.2.2 Hydrogeology

The Reno AASF is located within the Lemmon Valley Hydrographic Basin made up of two 

structural areas: the east Lemmon subarea and the Silver Lake subarea. These two hydrographic 

basins that comprise Lemmon Valley represent two separate groundwater reservoirs. In both 

basins, groundwater resources exist in fractured consolidated rocks in the uplands adjacent to and 

at depth beneath valley-fill, and in valley-fill alluvium that partly fills the structural depression 

underlying Lemmon Valley. The valley-fill alluvium represents the more productive and most 

important aquifer in both hydrographic basins due to its overall transmissivity, permeability, and 

extent. The thickness of the alluvial deposits is roughly 200 to 400 ft thick before bedrock is 

encountered. According to the Nevada Division of Water Resources online database, 

groundwater flow in the region flows southwest and the groundwater depth is approximately 30 

to 50 ft below ground surface (bgs) (Figure 2-3). The depth to static groundwater in July 2022 

observed during the SI ranged from approximately 41 to 60 ft bgs. Groundwater elevations from 

the SI are presented on Figure 2-4. Groundwater flow across the Facility may differ from the 

regional groundwater flow (southwest) due to the complex geology. Based on groundwater 

elevations calculated using depth to groundwater measurements, top of casing field 

measurements, and survey data collected during the SI, groundwater flow is generally to the 

north and west-northwest with an approximate gradient of 0.01 foot per foot (ft/ft). Survey 

deviations that affect top of casing elevation precision are documented in Section 5.8.

Groundwater sources and storage provide between 5 and 15% of the Truckee Meadows Water 

Authority (TMWA) water supply. TMWA owns 33 production wells that have a combined 

capacity of 63 million gallons per day. The wells are used for summer peak times and provide 

off-river reliability. In winter months, the wells are used for recharge as treated water is injected 

into the subsurface. TMWA operates an aquifer storage and recovery program in Lemmon 

Valley – Western Part. This project is associated with Nevada State Engineer’s Recharge Permit 

R-15. The recharge permit was issued on 19 November 2008 and allows for the recharge of up to 

1,000 acre-feet annually of Truckee River surface water imported to Lemmon Valley from 

Truckee Meadows. Permit R-15 also provides for four injection/recovery wells in the system 

located near the former Stead Air Force Base.

As part of the PA, Environmental Data Resources (EDRTM) conducted a well search for a 1-mile 

radius surrounding the Facility. Using additional online resources, such as state and local 

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

Facility. According to data received from the EDRTM Report for the Facility, three monitoring 

wells were located on the Facility, and several dozen are located within a 1-mile radius of the 

Facility. A large number of wells within a one-mile radius in all directions are also identified and 

classified as either domestic, public water supply, or unspecified wells (Figure 2-3), including a 
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recharge/injection well and replacement public supply/recharge well near the western facility 

boundary and at an interpreted downgradient hydrogeologic location from the AOIs. The 

recharge/injection well and replacement public supply/recharge well located approximately 0.1-

mile west of the Facility are completed to approximate depths of 840 and 600 ft bgs, 

respectively. The public supply well located approximately 0.3-mile to the north of the Facility is 

completed to a depth of approximately 647 ft bgs. The public supply well located approximately 

0.8-mile to the south of the Facility is completed to a depth of approximately 682 ft bgs. As 

identified in the PA Report (AECOM, 2020), three monitoring wells located on the Facility were 

part of a previous RI that concluded in 2018 and were abandoned on 5 September 2018

(AECOM, 2020). The Facility’s potable water is supplied by TMWA and Washoe County.

2.2.3 Hydrology

The Reno AASF has an approximate elevation of 5,000 ft amsl. The area is relatively flat, and 

the immediate vicinity of the Facility and has a shallow slope to the southeast. Surface water 

runoff from the Facility drains to the west. Stormwater is channeled from the pavement surfaces 

of the Facility into two underground stormwater interceptors that discharge to open flow 

channels on the west side of Army Aviation Drive. Other drainage features located on the 

Facility include open swales, gutters in the parking lot, gutters on the helicopter tarmac on the 

east side of the AASF and drop inlets. Surface water within the basin in which the Facility is 

located generally flows in a southern direction towards nearby playas.

Since 1944, surface water from the Truckee River has been imported from the TMWA through a 

pipeline to serve the former Stead Air Force Base. In the 1960s, importation of Truckee River 

water into Lemmon Valley was expanded to serve the area of Raleigh Heights in the southern 

part of the Lemmon Valley. Currently, TMWA continues to import Truckee River water into 

Lemmon Valley each year, a portion of which serves their customers directly, with the remainder 

being stored in the groundwater aquifer in Lemmon Valley – Western Part. While the TMWA 

obtains its water supply from both surface water and groundwater, surface water sources and 

storage provide between 85 and 95 percent (%) of the TMWA water supply. Surface water is 

treated at Chalk Bluff and Glendale Treatment Plants before distribution into the system, and the 

groundwater is pumped from wells throughout the service territory.

The City of Reno operates a wastewater treatment plant in Lemmon Valley – Eastern Part, 

southeast of the Reno-Stead Airport, near Swan/Lemmon Lake. The Reno-Stead Water 

Reclamation Facility is located adjacent to the basin boundary with Lemmon Valley – Western 

Part and treats wastewater received primarily from residential properties, along with some 

commercial and industrial properties, and the Reno AASF. The plant has a treatment capacity up 

to 2 million gallons per day, with planned improvements to accommodate up to 4 million gallons 

per day. Treated effluent is pumped from the treatment plant to various locations for reuse within 

Lemmon Valley. Reuse of effluent from the Reno-Stead Water Reclamation Facility is 

authorized by the Nevada State Engineer under Permit 4541S05 and by the Nevada Division of 

Environmental Protection under Permit NS2008500. Permitted use of the treated effluent 

includes irrigation of Sierra Sage Golf Course, North Valleys Sports Complex, and Mayors Park. 

On-site reuse of effluent at the Reno-Stead Water Reclamation Facility is also permitted for 

landscape irrigation and for an onsite effluent truck fill station for construction water. Delivery 

of effluent is also permitted to nearby Swan/Lemmon Lake to support wildlife habitat under an 
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agreement with the US Bureau of Land Management. Washoe County also operates a smaller 

capacity wastewater treatment plant in Lemmon Valley – Eastern Part. The Lemmon Valley 

Wastewater Reclamation Facility operates at approximately 300,000 gallons per day, and 

effluent reuse from this facility does not occur. Several times per year, polished effluent is 

discharged to Lemmon Lake Playa (Swan/Lemmon Lake), where it rapidly evaporates. Surface 

water features in the region are shown in Figure 2-5.

2.2.4 Climate

Reno AASF is situated in western Nevada and in the rain shadow of the Sierra Nevada mountain 

range. Being in the high desert of the Great Basin, the area experiences large temperature ranges 

on both a diurnal and annual scale. During the summer, afternoon highs are often above 90 

degrees Fahrenheit (°F), but at night, the air mass can cool down to about 50 °F. This area 

experiences a typical four seasons, though spring and fall can be short, as is common for midlatitude dry climates. Reno receives an average of 11.12 inches of precipitation per calendar 

year, which primarily occurs between the months of November and March. The warm half of the 

year is relatively dry, with a secondary precipitation maximum in May. An average of 23.5 

inches of snow falls in Reno annually, also occurring primarily between November and March 

(AECOM, 2020).

2.2.5 Current and Future Land Use

Presently, the Reno AASF is a fully developed NVARNG military training facility comprised of 

three large structures, four small structures, a helicopter landing pad, a large, paved parking area 

west of the armory, and a large gravel lot to the east of the armory building used for equipment 

parking and storage. Building structures on the Facility include an Armory Building, AASF, 

Field Maintenance Shop (FMS), Operational Support Airlift, Hazardous Materials Storage 

Building, Fire Pump House, and Gymnasium. The current land use is listed as General Industrial. 

Future land use is not anticipated to change (AECOM, 2020). The Facility is within a fenced 

boundary with limited access. The Facility has an access point from Army Aviation Drive. Each 

area within the Facility boundary requires an escort and approved Facility access including sitespecific badging.

2.2.6 Sensitive Habitat and Threatened/Endangered Species

A wildlife survey has not occurred at the Facility, and the Facility does not have any significant 

areas of habitat. The following species have not been identified at the Facility but may be present 

in the surrounding area.

The following species are listed as federally endangered, threatened, proposed, and/or candidate 

species in Washoe County, Nevada (U.S. Fish and Wildlife Services, 2021):

Birds:

Western, Yellow-Billed Cuckoo, Coccyzus Americanus Occidentalis (threatened)

Yellow-Billed Cuckoo, Coccyzus Americanus (threatened)

Fishes:

Lahontan Cutthroat Trout, Oncorhynchus Clarkii Henshawi (threatened)
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Cui-ui, Chasmistes Cujus (endangered)

Warner Sucker, Casostomus Warnernsis (threatened)

Amphibians:

Sierra Nevada Yellow-Legged Frog, Rana Sierra (endangered)

Flowering Plants:

Webber Ivesia, Ivesia Webberi (threatened)

Steamboat Buckwheat, Eriogonum Ovalifolium Var. Williamsiae (endangered)

Insects:

Carson Wandering Skipper, Pseudocopaeodes Eunus Obsurus (endangered)

2.3 HISTORY OF PFAS USE

One AOI, where aqueous film-forming foam (AFFF) may have been used, stored, disposed, or 

released historically, was identified in the PA (AECOM, 2020) at the Reno AASF. Two AOIs 

were chosen for the SI based on SI scoping discussions. During the SI scoping discussions, a 

second AOI was identified (AOI 2 – Stockpiled Soils) which received soils excavated from 

AOI 1.

The Former Firetruck Bay of the Reno AASF formerly housed a single standard crash fire rescue 

truck and related equipment until the late 1980s, when the truck was returned or sold due to the 

lack of trained personnel to operate the truck. Since AFFF use was not recorded on site, it is 

unclear if AFFF was ever stored on the truck. Presently, the South Hangar is fitted with an AFFF 

foam deluge fire protection system, which features a fire suppression system throughout the 

hangar, and a large AFFF storage tank housed where the firetruck formerly sat. There are no 

drains in the room that houses the AFFF storage tank. All drains within the Facility at the AASF 

are routed to the local water treatment plant, Reno-Stead Water Reclamation Facility, located 

approximately 5 miles southeast of the Facility.

Portable Tri-MaxTM hand-truck fire extinguishers containing AFFF were previously stored in 

various places on and near the parking apron from approximately the mid-1990s through the 

early 2000s. There is no record of these hand-trucks being used in training or emergency 

situations. The Tri-MaxTM units were replaced with two different types of extinguishers, one that 

contains AFFF, and one that does not contain AFFF. Only one unit containing AFFF exists on 

base and is located in the C12 hangar immediately adjacent to the Rotary Wing Parking Apron.

The Potential Secondary Source Area, located west of the airfield, contained stockpiled soil 

excavated from the airfield during apron expansion and resurfacing activities. These excavation 

activities began in December 2018 and were completed in May 2021. A description of each AOI 

is presented in Section 3.
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Figure 2-2

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) NV

Date:...................May 2023

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0 4,800

Feet

Data Sources: 

ESRI 2020

AECOM 2019

Date:........December 2023

Prepared By:.............WSP

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

) NV

Figure 2-3

Groundwater Features

Swan Lake

Hydrology/Hydrogeology

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Flow Direction

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Recharge Well, Replacement
Site Inspection Report

Reno Army Aviation Support Facility, Nevada Version: FINAL

EA Engineering, Science, and Technology, Inc., PBC 2-12

This page intentionally left blank
#*

#*

#*

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4954.0

AOI01-05

4953.8

AOI01-01

4958.8

AOI01-07

4959.8

AOI02-02

4954.2

Army National Guard Site Inspections

Site Inspection Report

Reno Army Aviation Support Facility 

Reno, Nevada

3

0 200

Feet

Data Sources: 

ESRI 2020

AECOM 2019

Date:.................May 2022

Prepared By:.............WSP

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

) NV

Facility Data

Area of Interest (AOI)

Potential PFAS

Release

Sample Type

!( Soil Boring and Temporary

Groundwater Well

#* Temporary Groundwater Well

Former

Firetruck Bay

Figure 2-4

Groundwater Elevations, July 2022

AOI-01

Former Firetruck Bay 

and Rotary Wing 

Parking Area

AOI-02

Stockpiled Soils

Hydrology/Hydrogeology

Groundwater Elevation Contour (1-Foot

Interval)

Calculated Groundwater Flow Direction
Site Inspection Report

Reno Army Aviation Support Facility, Nevada Version: FINAL

EA Engineering, Science, and Technology, Inc., PBC 2-14

This page intentionally left blank
Figure 2-5

Surface Water Features

Peavine

Creek-Truckee

River

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Purdy Cree

k

Bull Ranch Creek

Jones Creek

3

0 6,000

Feet

Data Sources: 

ESRI 2020

AECOM 2019

Facility Data

Facility Boundary

Hydrology/Hydrogeology

River/Stream

Approximate Surface Water Flow Direction

Wetland

Watershed

Swan/Lemmon Lake

Date:.................May 2023

Prepared By:............WSP

Prepared For:.......USACE

Army National Guard Site Inspections

Site Inspection Report

Reno Army Aviation Support Facility 

Reno, Nevada

) NV

Silver Lake
Site Inspection Report

Reno Army Aviation Support Facility, Nevada Version: FINAL

EA Engineering, Science, and Technology, Inc., PBC 2-16

This page intentionally left blank
Site Inspection Report

Reno Army Aviation Support Facility, Nevada Version: FINAL

EA Engineering, Science, and Technology, Inc., PBC 3-1

3. SUMMARY OF AREAS OF INTEREST

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

or released historically. Based on the PA findings, one potential release area was identified at the 

Reno AASF and identified as AOI 1 - Former Firetruck Truck Bay and Rotary Wing Parking 

Area. A second AOI was identified during the SI planning process (AOI 2 – Stockpiled Soils). 

AOI 2 is an area that received soils that were excavated from AOI 1. The AOIs are shown on 

Figure 3-1.

3.1 AOI 1 – FORMER FIRETRUCK BAY AND ROTARY WING PARKING AREA

AOI 1 consists of the Former Firetruck Bay and Rotary Wing Parking Area. The South Hangar, 

located centrally on site, formerly housed a single standard crash fire rescue truck and related 

equipment until the late 1980s, when the truck was returned or sold due to the lack of trained 

personnel to operate the truck. Since AFFF use was not recorded on site, it is unclear if AFFF 

was ever stored on the truck. There are no records of the truck ever being used for fire training or 

emergency response.

Presently, the South Hangar is fitted with an AFFF foam deluge fire protection system, which 

features a fire suppression system throughout the hangar, and a large AFFF storage tank housed 

where the firetruck formerly sat. The large fire suppression tank, according to the label found on 

said tank, is a model CCS3-704VA tank built in 1990 by Arrow Tank & Engineering Company. 

The tank is in good condition, has a rubber diaphragm, and shows no signs of past or present 

leakage. There are no drains in the room that houses the AFFF storage tank; however, drains do 

exist in the main portion of the South Hangar, which leads to a sand and oil separator on site. All 

drains within the Facility at the Reno AASF are routed to the local water treatment plant, RenoStead Water Reclamation Facility, located approximately 5 miles southeast of the Facility. There 

are no records or recollection from interviewees of any incident in which the fire suppression 

system was used or tested.

Portable Tri-MaxTM hand-truck fire extinguishers containing AFFF were previously stored in 

various places on and near the parking apron from approximately the mid-1990s through the 

early 2000s. These extinguishers were serviced regularly by ABC Fire and turned into the 

Carson City Warehouse Defense Reutilization and Marketing Office in the early 2000s. There is 

no record of these hand-trucks being used in training or emergency situations. The Tri-MaxTM

units were replaced with two different types of extinguishers, one that contains AFFF, and one 

that does not contain AFFF. Only one unit containing AFFF exists on base and is located in the 

C12 hangar immediately adjacent to the Rotary Wing Parking Apron. The remaining fire 

extinguishers, which do not contain AFFF, continue to be moved around various places on the 

Rotary Wing Parking Apron Area.

3.2 AOI 2 – STOCKPILED SOILS

The Potential Secondary Source Area, located west of the airfield, contained stockpiled soil 

excavated from the airfield during apron expansion and resurfacing activities. These excavation 

activities began in December 2018 and were completed in May 2021. Approximately 24 inches 

of native soil was removed during the apron expansion and backfilled with engineered fill 
Site Inspection Report

Reno Army Aviation Support Facility, Nevada Version: FINAL

EA Engineering, Science, and Technology, Inc., PBC 3-2

meeting structural requirements of the tarmac. The tarmac footprint was repaved and the native 

soils, predominately fine-grained materials were relocated to the west and bladed out to a 

maximum of 4 inches with RTAA approval.

3.3 ADJACENT SOURCES

One potential off-Facility source of PFAS was identified adjacent to the Facility in the PA 

(AECOM, 2020) and is not under the control of the NVARNG. A description of the off-Facility 

source is presented below.

Based on historic information, a potential source (fire training area) identified in the PA 

(AECOM, 2020) is located hydraulically downgradient of the Facility and is not expected to 

impact PFAS concentrations in the groundwater underlying the Facility. However, potential 

AFFF use on the Reno-Stead Airport property is unknown and may have included the use of 

AFFF upgradient of the site.

3.3.1 Reno-Stead Airport

The Reno-Stead Airport began operations in 1942 as the Reno Army Air Base, an air base built 

by the Army Air Corps and used by the Air Force during World War II. It was renamed “Stead 

Air National Guard Base” in 1951, and renamed “Stead Air Force Base” the same year. The base 

was closed in 1966 and transferred to the City of Reno and since then has been operated as the 

Reno-Stead Airport. The Reno-Stead Airport covers an area of 5,000 acres at an elevation of 

5,050 ft amsl with two runways. The Reno-Stead Airport was formerly a military installation 

until 1966 and is currently owned by the Reno-Tahoe Airport Authority. As a military 

installation, the Reno-Stead Airport was used primarily for training including survival and flying. 

The Reno AASF is located within the Reno-Stead Airport boundary (Figure 3-1) and the runway 

is located to the east of the Reno AASF. A fire academy is located at the Reno-Stead Airport

where, reportedly, fire training using AFFF has occurred historically and to present. The fire 

academy is located downgradient of the AASF facility based on historic information collected 

during the PA. The Reno Fire Department supports the Airport and does not have its own on-site 

fire support. In addition, the use of AFFF as an emergency response measure at the Reno-Stead 

Airport is unknown; emergency use and other AFFF uses or releases may have occurred 

upgradient of the Facility.

No other off-Facility source areas were identified in the PA Report. 
Army National Guard Site Inspections

Site Inspection Report

Reno Army Aviation Support Facility 

Reno, Nevada

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Reno Stead

Airport

AOI-01

Former Firetruck Bay 

and Rotary Wing 

Parking Area

Former 

Firetruck Bay

AOI-02

Stockpiled Soils

3

0 1,200

Feet

Data Sources: 

ESRI 2020

AECOM 2019

Date:........December 2023

Prepared By:.............WSP

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

) NV

Facility Data

Facility Boundary

Area of Interest (AOI)

Potential PFAS

Release

Hydrology

River/Stream

Figure 3-1

Areas of Interest

Existing Wells

A@ Monitoring Well, Plug or

Abandonment

&( Commercial, Existing

A?@ Monitoring Well, Existing

&( Domestic, Existing

&( Domestic, Plug or Abandonment

&: Irrigation

&: Industrial, Existing

&( Stock

?@ Other

!C Public Supply (Municipal) /

Recharge Well

&% Public Supply (Municipal) /

Recharge Well, Replacement
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4. PROJECT DATA QUALITY OBJECTIVES

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

Federal Policy (UFP) - QAPP Addendum (EA/Wood, 2022a), the objective of the SI was to 

identify whether there has been a release to the environment at the two AOIs. 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 the presence or absence of relevant compounds at the sampled AOIs.

4.1 PROBLEM STATEMENT

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

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

are presented in Section 6.1 of this Report.

4.2 INFORMATION INPUTS

Primary information inputs for the SI include the following:

• The PA Report for the Reno AASF (AECOM, 2020)

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

accordance with the site-specific UFP –QAPP Addendum (EA/Wood 2022a)

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

parameters measured at the time of sampling.

4.3 STUDY BOUNDARIES

The scope of the SI was bounded horizontally by the property limits of the Facility (Figure 2-1 

and 3-1). The scope of the SI was bounded vertically by the depth of temporary monitoring wells 

installed within groundwater, where encountered (maximum depth of 71 ft bgs). Off-facility

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

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

with property owner(s). Temporal boundaries were limited to the earliest available time field 

resources were available to complete the study.

4.4 ANALYTICAL APPROACH

Samples were analyzed by Eurofins, accredited under the Department of Defense (DoD)

Environmental Laboratory Accreditation Program (DoD ELAP; Accreditation Number 1.01) and 

the National Environmental Laboratory Accreditation Program (NELAP; Certificate Number 

021). Data were compared to applicable SLs within this document and decision rules as defined 

in the UFP-QAPP Addendum (EA/Wood 2022a).

4.5 DATA USABILITY ASSESSMENT

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

conclusion of data collection activities that uses the results of both data verification and 
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validation in the context of the overall project decisions or objectives. Using both quantitative 

and qualitative methods, the assessment determines whether project execution and the resulting 

data have met installation specific DQOs. Both sampling and analytical activities are considered 

to assess whether the collected data are of the right type, quality, and quantity to support the 

decision-making (DoD 2019a, DoD 2019b, USEPA 2017).

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

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

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

requirements of the UFP-QAPP (EA/Wood, 2022a).
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5. SITE INSPECTION ACTIVITIES

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

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

implemented in accordance with the following approved documents.

• Final Preliminary Assessment Report, Reno Army Aviation Support Facility, 

Reno, Nevada, dated August 2020 (AECOM, 2020)

• Final Programmatic Uniform Federal Policy-Quality Assurance Project Plan,

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

Installations, Nationwide, dated December 2020 (EA, 2020)

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

Addendum, Reno Army Aviation Support Facility, Nevada, dated May 2022

(EA/Wood, 2022a)

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

(EA, 2020b)

• Final Accident Prevention Plan/Site Safety and Health Plan, Reno Army Aviation 

Support Facility, Reno, Nevada, dated June 2022 (EA/Wood 2022b).

The SI field activities were conducted from 05 to 22 July 2022, and consisted of utility 

clearance, hand augering to clear utilities and collect surface soil samples, hollow stem 

auger (HSA) boring advancement and soil sample collection, temporary monitoring well 

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

were conducted in accordance with the UFP-QAPP Addendum (EA/Wood, 2022a), 

except as noted in Section 5.8.

The following samples were collected during the SI and analyzed for 24 compounds via 

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

Version 5.3 Table B-15 to fulfill the project DQOs:

• Eighteen (18) soil samples from 6 boring locations;

• Eleven (11) grab groundwater samples from 11 temporary well;

• Twenty-one (21) quality assurance (QA)/QC samples.

Figure 5-1 provides the sample locations for all media (soil and groundwater) across the 

Facility. Table 5-1 presents the list of samples collected for each medium. Field 

documentation is provided in Appendix B. A log of Daily Notice of Field Activity was 

completed throughout the SI field activities, which is provided in Appendix B1. 

Sampling forms are provided in Appendix B2, land survey data is provided in Appendix 

B3, a Field Change Request Form is provided in Appendix B4, and the investigationderived waste (IDW) placement location is provided in Appendix B5. Additionally, a 

photographic log of field activities is provided in Appendix C.
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5.1 PRE-INVESTIGATION ACTIVITIES

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

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

water. Details of these activities are presented below.

5.1.1 Technical Project Planning

The U.S. Army Corps of Engineers (USACE) TPP Process, Engineers Manual (EM) 200-1-2 

(Department of the Army 2016a) defines four phases to project planning: (1) defining the project 

phase; (2) determining data needs; (3) developing data collection strategies; and (4) finalizing the 

data collection plan. The process encourages stakeholder involvement in the SI, beginning with 

defining overall project objectives, including DQOs, and formulating a sampling approach to 

address the AOIs identified in the PA.

A combined TPP Meeting 1 and 2 was held on 18 January 2022. The combined TPP Meeting 1 

and 2 was conducted in general accordance with EM 200-1-2. The stakeholders for this SI 

included ARNG, NVARNG, Nevada Division of Environmental Protection (NDEP), USACE, 

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 UFP-QAPP Addendum (EA/Wood, 2022a).

A TPP Meeting 3 was held after the field event to discuss the results of the SI on 17 August 

2023. Meeting minutes for TPP 3 are included in Appendix D of this report. The TPP 3 meeting 

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

5.1.2 Utility Clearance

WSP USA Environment & Infrastructure, Inc. (WSP), previously doing business as Wood 

Environment & Infrastructure Solutions, Inc., contacted the Utility Notification Center to notify 

them of intrusive work at the Facility. WSP contracted Penhall Company (Penhall), a private 

utility location service, to perform utility clearance and concrete cutting at the Facility. Utility 

clearance was performed at each of the proposed boring locations on 14 April 2022 with input 

from the WSP field team. General locating services and ground-penetrating radar (GPR) were 

used to complete the clearance. Additionally, the first 5 ft of each boring were pre-cleared by 

WSP or WSP’s drilling subcontractor, Yellow Jacket Drilling Services, LLC (Yellow Jacket),

using a hand auger prior to the advancement of drilling equipment to verify utility clearance in 

shallow subsurface where utilities would typically be encountered.

5.1.3 Source Water and PFAS Sampling Equipment Acceptability

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

acceptability criteria, as defined in the UFP-QAPP Addendum, prior to the start of field 

activities. A sample from an outside spigot (potable water source) at the Reno AASF, was 

collected on 14 April 2022, prior to mobilization and analyzed for PFAS by LC/MS/MS 

compliant with QSM 5.3 Table B-15. The potable water source sample was delayed in transit 

and arrived at the laboratory outside of the specified acceptable temperature. The data was 

deemed usable by a qualified WSP chemist, and the data validation is included in Appendix A.
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The results of the sample of the potable water source used for decontamination of drilling 

equipment during the SI are provided in Appendix F. The potable water source was deemed 

usable. A discussion of the results is presented in the Data Usability Assessment (Appendix A).

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

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

environment was provided in the Standard Operating Procedures appendix to the Programmatic 

UFP-QAPP (PQAPP) (EA, 2020).

5.2 SOIL BORINGS AND SOIL SAMPLING

Soil samples were collected in July 2022 via HSA drilling methods in accordance with Standard 

Operating Procedure 025 Soil Sampling (EA/Wood, 2022a). A split spoon sampler was used to 

collect continuous soil cores to the target depth. A hand auger was used to clear the top 5 ft of 

the boring in compliance with utility clearance procedures. The soil boring locations are shown 

on Figure 5-1, and boring sample depths are provided in Table 5-1.

Three (3) discrete soil samples were collected from each of the six (6) specified soil borings

(AOI01-01, AOI01-02, AOI01-03, AOI01-04, AOI02-01, and AOI02-02): one sample at the 

surface (0 to 2 ft bgs) and two subsurface soil samples. The surface soil sample for AOI02-02 

was taken from stockpiled soil at a depth of 7 to 8 feet which is considered to be an equivalent 

depth of 0 to 2 feet below the natural ground surface. All soil sample locations are shown on 

Figure 5-1. Subsurface samples were defined as intermediate and deep samples (EA/Wood, 

2022a). Intermediate samples were collected at 14 to 15 ft bgs at AOI01-01, AOI01-03, AOI01-

04, and AOI02-01 and at a depth of 22 to 23 ft at AOI02-02 (on stockpiled soils, which is 

considered to be an equivalent depth of 14 to 15 feet below natural ground surface). Deep 

samples were collected approximately 1 ft above the groundwater table at AOI01-01, AOI01-02, 

AOI01-03, AOI01-04, AOI01-05, AOI01-06, AOI01-07, AOI02-01, and AOI02-02.

Groundwater during drilling was encountered at depths ranging from approximately 41 to 61 ft 

bgs. Total boring completion depths, to accommodate temporary well installation, ranged from

approximately 45 to 71 ft bgs.

During drilling, soil cores were continuously logged for lithological descriptions by a field 

geologist using the Unified Soil Classification System. The lithology below the Facility to the 

depth of the borings consisted predominately of silty and poorly graded sands with interbedded 

layers of clayey sand, medium plastic fines (clay), and less plastic fines (silt). A photoionization 

detector (PID) was used to screen the breathing zone during boring activities as a part of personal 

safety requirements. Observations and measurements were recorded on sampling forms 

(Appendix B2) and in a non-treated field logbook. Depth interval, recovery thickness, PID 

concentrations, moisture, relative density, Munsell color, and Unified Soil Classification System

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

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

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

standard COC procedures to the laboratory (Eurofins) and analyzed for PFAS (LC/MS/MS 

compliant with QSM Version 5.3 Table B-15), TOC (USEPA Method 9060A), pH (USEPA 
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Method 9045D), and grain size (ASTM Method D-422) in accordance with the UFP-QAPP 

Addendum (EA/Wood, 2022a).

Field duplicate samples (Table 5-1) were collected at a rate of 10% and analyzed for the same 

parameters as the accompanying samples. Matrix Spike (MS)/ matrix spike duplicates (MSDs)

were collected at a rate of 5% and analyzed for the same parameters as the accompanying 

samples. In instances when non-dedicated sampling equipment was used, such as a hand auger 

for the shallow soil samples, one equipment blank (EB) was collected per day and analyzed for 

the same parameters as the soil samples. A temperature blank was placed in each cooler for use 

in confirming that samples were preserved at or below 6 degrees Celsius (°C) during shipment.

5.3 TEMPORARY WELL INSTALLATION AND GROUNDWATER SAMPLING

Temporary wells were installed using a HSA BK-81 system. Temporary well waivers and notice 

of intent (NOI) to drill the temporary wells were filed with Nevada Division of Water Resources 

(NVDWR) prior to mobilization. The waivers and NOIs were submitted in person to NVDWR

by Yellow Jacket and WSP on 05 July 2022. Once the borehole was advanced to the desired 

depth, a temporary well was constructed of a 5-ft section of 2-inch Schedule 40 poly-vinyl 

chloride (PVC) screen with sufficient casing to reach the ground surface. New PVC pipe and 

screen were used at each location to avoid cross contamination between locations. The screen 

intervals for the temporary wells are provided in Table 5-2.

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

groundwater to infiltrate and recharge the temporary well intervals. After the recharge period, the 

temporary wells were bailed with a PFAS-free bailer to remove fines. Groundwater samples 

were collected using a low-flow bladder pump equipped with PFAS-free HDPE tubing. The 

temporary wells were purged at a rate determined in the field to reduce turbidity and draw down 

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

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

and recorded on the field sampling form (Appendix B2) before each sample was collected in a 

separate container. Shaker tests were inadvertently not performed for groundwater samples. This 

deviation is described in Section 5.8. 

Each sample was collected in 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 (Eurofins) and analyzed for PFAS by LC/MS/MS 

compliant with QSM Version 5.3 Table B-15 in accordance with the UFP-QAPP Addendum 

(EA/Wood, 2022a).

Field duplicate samples (Table 5-1) 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. Two (2) field blanks (FBs) were collected 

in accordance with the UFP-QAPP Addendum (EA/Wood, 2022a). In instances when nondedicated sampling equipment was used, such as a GeotechTM bladder pump, one EB was 

collected a day and analyzed for the same parameters as the groundwater samples. A temperature 

blank was placed in each cooler for use in confirming that samples were preserved at or below 

6°C during shipment.
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Following surveying (described below in Section 5.5), the temporary wells were abandoned in 

accordance with the SI UFP-QAPP Addendum (EA/Wood, 2022a) by removing the PVC and 

backfilling the hole with bentonite chips to within 20 ft of the ground surface and the remaining 

depth was abandoned with concrete. The borings were installed in dirt, asphalt, and concrete 

areas and all boring locations were restored to original condition.

5.4 SYNOPTIC WATER LEVEL MEASUREMENTS

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

measurements were collected from the newly installed temporary monitoring wells. Water level 

measurements were taken from the survey mark on the northern side of the well casing.

Groundwater elevation data is provided in Table 5-3. A groundwater flow contour map is 

provided as Figure 2-4.

5.5 SURVEYING

The ground surface of each borehole was surveyed using a Trimble R10 real-time kinematic 

differential global positioning system. Positions were collected in the applicable Universal 

Transverse Mercator zone projection with World Geodetic System 1984 datum (horizontal) and 

North American Vertical Datum 1988 (vertical). The top of casing could not be accurately 

surveyed because the casing could not be sufficiently stabilized due to the lack of filter pack 

within the borehole, therefore distance from the surveyed ground surface elevation to the top of 

casing was field measured to 0.1 ft to calculate the top of casing elevation. Complete details on 

deviations from the UFP-QAPP are presented in Section 5.8. Surveying data were collected by 

Summit Engineering Corps. (Summit) on 19 July 2022 and are provided in Appendix B3.

5.6 INVESTIGATION-DERIVED WASTE

As of the date of this report, the disposal of PFAS IDW is not regulated federally. IDW 

generated during the SI is considered non-hazardous waste and was managed in accordance with 

the UFP-QAPP Addendum (EA/Wood, 2022a).

Soil IDW was placed in Department of Transportation (DOT)-approved steel drums, labeled, and 

stored in a designated consolidation area. The soil IDW was not sampled and assumes the 

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

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

decontamination fluids) was contained in labeled, 55-gallon DOT-approved steel drums and

stored in the same designated consolidation area as the soil IDW drums. The liquid IDW was not 

sampled and assumes the characteristics of the associated groundwater samples collected from 

that source location.

The IDW disposal is being managed under a separate contract (EA Engineering, Science, and 

Technology, Inc., 2021). Specifics on the disposal of liquid IDW will be addressed in an IDW 

Technical Memorandum.
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Geographic coordinates of the approximate center of the IDW consolidation area were surveyed. 

The IDW consolidation area is displayed on the figure in Appendix B5. IDW will remain in this 

location until it is removed for off-site disposal. 

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

LC/MS/MS analyzed samples, compliant with QSM Version 5.3 Table B-15, at Eurofins in 

Lancaster, Pennsylvania, a DoD ELAP and NELAP-certified laboratory.

One soil sample per AOI was also analyzed for TOC using USEPA Method 9060A and pH by 

USEPA Method 9045D, and grain size using ASTM Method D-422.

5.8 DEVIATIONS FROM SI UFP-QAPP ADDENDUM

Deviations from the UFP-QAPP Addendum (EA/Wood, 2022a) occurred based on conditions 

encountered during field activities. These deviations were discussed between EA, WSP, ARNG, 

USACE, and NVARNG. Deviations from the UFP-QAPP Addendum are noted below:

• AOI01-07: This location was added following the Site walk with ARNG and NDEP. A 

field change request form was submitted and is included in Appendix B4. This location 

was chosen to evaluate the decommissioned leach field that was used historically by the 

AASF. The leach field was fenced and had limited vehicle access; therefore, the 

sampling location was placed to the south of the fenced area. The direction of 

groundwater flow was unknown during the initial Site walk, and the location of AOI01-

07 was upgradient of the leach field based on the groundwater elevation measurements 

collected during the SI.

• Shaker tests were inadvertently not performed on the groundwater samples. The purpose 

of Shaker tests is to provide the laboratory with advance notice of samples that foam with 

agitation. The laboratory did not indicate any issue with foaming during the groundwater 

sample analyses; therefore, data quality was not impacted by the Shaker tests omission.

• The UFP-QAPP specified the well casing was to be surveyed to a vertical accuracy of 

0.01 ft. The surveyor attempted to survey the top of casing but was unable to obtain an 

accurate survey because the well casing could not be sufficiently stabilized due to the 

lack of filter pack within the borehole. The surveyor attempted to temporarily stabilize 

the casing but was unsuccessful. The ground surface elevation was surveyed to 0.01 ft. 

WSP field personnel measured from top of casing down to the surveyors ground surface 

point to calculate a top of casing elevation at each temporary well. This field 

measurement was to 0.1 ft; therefore, the corresponding groundwater elevation 

calculation was also to the nearest 0.1 ft. 
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Table 5-1. Site Inspection Samples by Medium

Reno AASF, Reno, NV

Site Inspection Report

Sample Identification

Sample Collection 

Date

Sample Depth

(ft bgs)

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

Comments

Soil Samples

AOI01-01-SB-1-2 7/15/2022 1-2 X

AOI01-01-SB-14-15 7/18/2022 14-15 X

AOI01-01-SB-50-51 7/18/2022 50-51 X

AOI01-02-SB-1-2 7/15/2022 1-2 X

AOI01-02-SB-14-15 7/15/2022 14-15 X

AOI01-02-SB-50-51 7/15/2022 50-51 X

AOI01-03-SB-1-2 7/14/2022 1-2 X

AOI01-03-SB-14-15 7/14/2022 14-15 X

AOI01-03-SB-45-46 7/14/2022 45-46 X

AOI01-04-SB-0-2 7/7/2022 0-2 X X X X

AOI01-04-SB-15-16 7/8/2022 15-16 X

AOI01-04-SB-44-45 7/8/2022 44-45 X

AOI02-01-SB-0-2 7/12/2022 0-2 X X X X

AOI02-01-SB-14-15 7/12/2022 14-15 X

AOI02-01-SB- 55-56 7/13/2022 55-56 X

AOI02-02-SB-7-8 7/13/2022 7-8 X

AOI02-02-SB-22-23 7/13/2022 22-23 X

AOI02-02-SB-63-64 7/13/2022 63-64 X

FD-01 7/7/2022 0-2 X X X X Duplicate of AOI01-04-

SB-0-2

FD-02 7/15/2022 14-15 X Duplicate of AOI01-02-

SB-14-15

FD-01 MS/MSD 7/13/2022 22-23 X Duplicate of AOI02-02-

SB-22-23

Groundwater Samples

AOI01-01-GW 7/19/2022 NA X MS/MSD

AOI01-02-GW 7/18/2022 NA X

AOI01-03-GW 7/15/2022 NA X

AOI01-04-GW 7/19/2022 NA X

AOI01-05-GW 7/20/2022 NA X

AOI01-06-GW 7/21/2022 NA X

AOI01-07-GW 7/21/2022 NA X

AOI02-01-GW 7/20/2022 NA X

AOI02-02-GW 7/20/2022 NA X

AASF-01-GW 7/19/2022 NA X

AASF-02-GW 7/20/2022 NA X

FD-03 7/19/2022 NA X Duplicate of AOI01-02-

GW
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Sample Identification

Sample Collection 

Date

Sample Depth

(ft bgs)

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

Comments

Blank Samples

RENO-EB-01 7/7/2022 NA X Equipment Blank from 

Hand Auger

RENO-EB-02 7/8/2022 NA X Equipment Blank from 

Split Spoon Sampler

RENO-EB-03 7/12/2022 NA X Equipment Blank from 

Split Spoon Sampler

RENO-EB-04 7/13/2022 NA X Equipment Blank from 

Split Spoon Sampler

RENO-EB-05 7/14/2022 NA X Equipment Blank from 

Split Spoon Sampler

RENO-EB-06 7/15/2022 NA X Equipment Blank from 

Split Spoon Sampler

RENO-EB-07 7/15/2022 NA X Equipment Blank from 

Groundwater Sampling 

Pump

RENO-EB-08 7/18/2022 NA X Equipment Blank from 

Split Spoon Sampler

RENO-EB-09 7/18/2022 NA X Equipment Blank from 

Groundwater Sampling 

Pump

RENO-EB-10 7/19/2022 NA X Equipment Blank from 

Split Spoon Sampler

RENO-EB-11 7/20/2022 NA X Equipment Blank from 

Groundwater Sampling 

Pump

RENO-EB-12 7/21/2022 NA X Equipment Blank from 

Groundwater Sampling 

Pump

RENO-PW-01 7/13/2022 NA X Equipment Blank from 

Potable Water Tank

RENO-FB-011 7/13/2022 NA X Field Blank

RENO-FB-011 7/21/2022 NA X Field Blank

Notes:

1 – Field blanks were collected on two separate days, but given the same sample identification. The field blank results were 

reported in separate sample delivery groups. The sample collection date is used to differentiate between the two field blank 

samples.

ASTM = American Society for Testing and Materials

bgs = below ground surface

EB = equipment rinsate blank

FB = field blank

FD = field duplicate

LC/MS/MS = Liquid Chromatography Mass Spectrometry

MS/MSD = matrix spike/ matrix spike duplicate

PW = potable water

QSM = Quality Systems Manual
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Sample Identification

Sample Collection 

Date

Sample Depth

(ft bgs)

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

Comments

TOC = total organic carbon

USEPA = United States Environmental Protection Agency
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Table 5-2. Soil Boring Depths and Temporary Well Screen Intervals

Reno AASF, Reno, NV

Site Inspection Report

Area of Interest Boring Location

Soil Boring Depth

(ft bgs)

Temporary Well 

Screen Interval 1

(ft bgs)

1

AOI01-01 55 48.5-53.5 

AOI01-02 56.6 49.5-54.5 

AOI01-03 50 44-49 

AOI01-04 50 44-49 

AOI01-05 60 54-59

AOI01-06 45 39-44 

AOI01-07 45 38.5-43.5 

2

AOI02-01 60 54-59 

AOI02-02 71 65-70

Boundary Wells AASF-01 65 58.8-63.8

AASF-02 50 44-49 

Notes:

1 Temporary well screen set above total depth to capture groundwater interface

AASF = Army Aviation Support Facility

amsl = Above mean sea level

bgs = below ground surface

btoc = below top of casing

ft = feet

NA = not applicable

NAVD88 = North American Vertical Datum 1988
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Table 5-3. Groundwater Elevation

Reno AASF, Reno, NV

Site Inspection Report

Monitoring Well 

ID

Ground Elevation

(ft NAVD88)

Measured Top of 

Casing Stickup Height 

(ft)

Top of Casing 

Elevation1

(ft NAVD88)

Depth to Water

(ft btoc)

Groundwater 

Elevation

(ft NAVD 88)

AOI01-01 5007.41 1.5 5008.9 50.12 4958.8

AOI01-02 5005.75 1.25 5007.0 48.12 4958.9

AOI01-03 5003.49 1.5 5005.0 46.20 4958.8

AOI01-04 5000.20 1.0 5001.2 42.69 4958.5

AOI01-05 5002.91 2.0 5004.9 51.15 4953.8

AOI01-06 4999.80 1.0 5000.8 41.81 4959.0

AOI01-07 4999.60 1.5 5001.1 41.30 4959.8

AOI02-01 5007.00 1.5 5008.5 54.47 4954.0

AOI02-02 5013.84 0.7 5014.5 60.28 4954.2

AASF-01 5007.42 1.5 5008.9 55.70 4953.2

AASF-02 5003.08 1.0 5004.1 47.40 4956.7

Notes:

1 – Top of Casing Elevation was field measured to 0.1 ft from the surveyed ground surface elevation, therefore the groundwater 

elevations are reported to the nearest 0.1 ft. See Section 5.8 for complete UFP-QAPP deviation details

AASF – Army Aviation Support Facility

amsl = Above mean sea level

bgs = below ground surface

btoc = below top of casing

Ft = feet

NA = not applicable

NAVD88 = North American Vertical Datum 1988
Army National Guard Site Inspections

Site Inspection Report

Reno Army Aviation Support Facility 

Reno, Nevada

#*

#*

#*

!(

!(

!(

!(

!(

#*

!(

#*

AOI-02

Stockpiled Soils

AOI01-07

AOI01-06

AASF-01

AASF-02

AOI01-02

AOI01-03

AOI01-04

AOI02-01

AOI02-02

AOI01-05

AOI01-01

3

0 200

Feet

Data Sources: 

ESRI 2020

AECOM 2019

Date:..................May 2023

Prepared By:.............WSP

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

) NV

Facility Data

Area of Interest (AOI)

Potential PFAS

Release

Sample Type

!( Soil Boring and Temporary

Groundwater Well

#* Temporary Groundwater Well

Former

Firetruck Bay

Figure 5-1 

Site Inspection Sample Locations

AOI-01

Former Firetruck Bay 

and Rotary Wing 

Parking Area

Hydrology/Hydrogeology

Inferred Groundwater Flow Direction

Surface Water Flow Direction
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6. SITE INSPECTION RESULTS

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

presented in Section 6.1. A discussion of the results for the AOIs is provided in Sections 6.3 and 

6.4. Tables 6-2 through 6-6 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 (Assistant Secretary 

of Defense, 2022). The ARNG program under which this SI was performed follows this DoD 

policy. Should the maximum Facility concentration for sampled media exceed the SLs 

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

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

6-1.

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

Analyte2

Residential

(Soil)

(μg/kg)1

0-2 ft bgs

Industrial / Commercial

Composite Worker

(Soil)

(μg /kg) 1

2-15 ft bgs

Tap Water

(Groundwater)

(ng/L) 1

PFOA 19 250 6

PFOS 13 160 4

PFBS 1,900 25,000 601

PFHxS 130 1,600 39

PFNA 19 250 6

Notes:

1. Assistant Secretary of Defense. July 2022. Risk-Based Screening Levels in Groundwater and Soil using 

U.S. Environmental Protection Agency’s (EPA’s) Regional Screening Level Calculator. Hazard Quotient 

(HQ)=0.1. May 2022.

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

referred to as GenX) was not included as an analyte at the time of this SI. Based on the CSM developed during 

the PA and revised based on SI findings, the presence of HFPO-DA is not anticipated at the facility because 

HFPO-DA is generally not a component of MIL-SPEC AFFF and based on its history including distribution 

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

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

Notes:

g/kg = microgram(s) per kilogram

ng/L = nanogram(s) per liter

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

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

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

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

ft bgs) and the industrial/commercial worker scenario is applied to shallow subsurface soil 
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results (2 to 15 ft bgs). The SLs are not applied to deep subsurface soil results (greater than 15 ft 

bgs) because 15 ft is the anticipated limit of construction activities.

6.2 SOIL PHYSICOCHEMICAL ANALYSES

To provide basic soil parameter information, one soil sample per AOI was analyzed for TOC,

pH, and grain size, which are important for evaluating transport through the soil medium. 

Appendix D contains the results of the TOC, pH, and grain size sampling.

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

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

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

lipophobic effects, electrostatic interactions, and interfacial behaviors. At relevant environmental 

pH values, certain PFAS are present as organic anions, and are therefore relatively mobile in 

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

be present in soil or sediment (Higgins and Luthy 2006; Guelfo and Higgins 2013). When 

sufficient organic carbon is present, organic carbon normalized distribution coefficients (Koc 

values) can help in evaluating transport potential, though other geochemical factors (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: Former Firetruck Bay and Rotary Wing Parking Area. The soil and groundwater results

are summarized in Tables 6-2 through 6-5. Soil and groundwater results are presented on 

Figures 6-1 through 6-7.

6.3.1 Soil Analytical Results

Soil samples were collected from four boring locations associated with AOI 1 during the SI

(AOI01-01 through AOI01-04). Figure 6-1 through Figure 6-5 present the ranges of detections 

in soil. Tables 6-2 through 6-4 summarize the soil results.

Surface soil (0 to 2 ft bgs) was sampled from boring locations AOI01-01 through AOI01-04. Soil 

was sampled from the shallow subsurface soils (14 to 15 ft bgs) and deep subsurface soil 

intervals (approximately 1 ft above the water table, ranging from 45 to 51 ft bgs) from boring 

locations AOI01-01 through AOI01-04.

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

SLs. PFOA was detected at one location (AOI01-04) at a concentration of 0.25 J μg/kg. PFOS 

was detected at two locations (AOI01-03 and AOI01-04) at concentrations of 11 and 1.3 μg/kg, 

respectively. PFHxS was detected at two locations (AOI01-03 and AOI01-04) at concentrations 

of 0.32 J and 0.36 J μg/kg, respectively. PFBS and PFNA were not detected in the surface soil 

samples.

PFBS, PFOS, and PFHxS were detected in the shallow subsurface soil at concentrations below 

their respective SLs at one location (AOI01-03) at concentrations of 1.4 J μg/kg, 2.1 J+ μg/kg, 
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and 1.1 μg/kg, respectively. PFOA and PFNA were not detected in the shallow subsurface soil 

samples at AOI 1.

PFOS was detected in the deep subsurface soil at one location (AOI01-03) with a concentration

of 0.76 J+ μg/kg. PFOA, PFBS, PFHxS, and PFNA were not detected in the deep subsurface soil 

samples at AOI 1.

6.3.2 Groundwater Analytical Results

Groundwater samples were collected from seven temporary wells associated with AOI 1 during 

the SI (AOI01-01 through AOI01-07). Figure 6-6 and 6-7 presents the ranges of detections in 

groundwater. Table 6-5 summarizes the groundwater results.

PFOA, PFOS, and PFHxS were detected at concentrations exceeding their respective SLs.

PFBS and PFNA were detected at concentrations below their respective SLs. A summary of the 

AOI01 detections of PFOA, PFOS, PFHxS, PFBSs, and PFNA are as follows:

• PFOA was detected at concentrations exceeding the SL at two locations AOI01-03 and

AOI01-07 with concentrations of 20 J and 7.8 ng/L, respectively. PFOA was detected at 

all other AOI 1 locations at concentrations below the SL with concentrations ranging 

from 0.46 J to 4.3 ng/L.

• PFOS was detected at concentrations exceeding the SL at four locations (AOI01-03, 

AOI01-04, AOI01-05, and AOI01-06) with concentrations of 67, 10, 6.1, and 10 ng/L, 

respectively. PFOS was detected at concentrations below the SL at the other locations 

(AOI01-01, AOI01-02, and AOI01-07) at concentrations ranging from 2.4 to 3.8 J+ ng/L.

• PFHxS was detected at a concentration exceeding the SL at one location (AOI01-03)

with a concentration of 54 ng/L. PFHxS was detected at all other locations (AOI01-01, 

AOI01-02, and AOI01-04 through AOI01-07) at concentrations ranging from 0.93 J to 29

ng/L.

• PFBS was detected at all seven locations (AOI01-01 through AOI01-07) below the SL, at 

concentrations ranging from 1.9 to 60 ng/L.

• PFNA was detected at three of seven locations (AOI01-03, AOI01-04, and AOI01-06) 

below the SL, at concentrations ranging from 0.52 J to 3.3 ng/L.

6.3.3 Conclusions

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

respective SLs. PFNA was not detected in soil at AOI 1. PFOA, PFOS, and PFHxS were 

detected in groundwater at concentrations above their respective SLs. PFBS and PFNA were 

detected in groundwater at concentrations below their respective SLs. Based on the exceedances 

of the SLs in groundwater, further evaluation at AOI 1 is warranted.
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6.4 AOI 2

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

AOI 2: Stockpile Soils. The soil and groundwater results are summarized in Table 6-2 through 

6-5. Soil and groundwater results are presented on Figures 6-1 through 6-7.

6.4.1 Soil Analytical Results

Soil samples were collected from two boring locations associated with AOI 2 during the SI

(AOI02-01 and AOI02-02). Figure 6-1 through 6-5 present the ranges of detections in soil. 

Tables 6-2 and 6-4 summarize the soil results.

Surface soil was sampled from both locations (AOI02-01 and AOI02-02) at depths of 0 to 2 and 

7 to 8 ft bgs (native soil below stockpiled soil), respectively. Soil was sampled from the shallow 

subsurface soils at locations AOI02-01 and AOI02-02 at depths of 14 to 15 and 22 to 23 ft bgs, 

respectively. The deep subsurface soil at AOI02-01 and AOI02-02 was sampled at an interval of 

approximately 1 foot above the water table which was approximately 55 to 56 and 63 to 64 ft 

bgs, respectively.

No relevant compounds were detected in soils at AOI 2.

6.4.2 Groundwater Analytical Results

Groundwater samples were collected from two temporary wells associated with AOI 2 during the 

SI. Figure 6-6 and 6-7 presents the ranges of detections in groundwater. Table 6-5 summarizes 

the groundwater results.

Groundwater was sampled from temporary monitoring wells AOI02-01 and AOI02-02. PFOA, 

PFBS, PFOS, and PFHxS were detected at concentrations below their respective SLs. PFOA was 

detected at AOI02-01 and AOI02-02, each with concentrations of 0.51 J ng/L. PFBS was 

detected at AOI02-01 and AOI02-02 at concentrations of 26 and 10 ng/L, respectively. PFOS 

was detected at AOI02-01 and AOI02-02 at concentrations of 0.84 J and 2.8 ng/L, respectively.

PFHxS was detected at AOI02-01 and AOI02-02 at concentrations of 8.9 and 3.3 ng/L, 

respectively. PFNA was not detected in the groundwater samples.

6.4.3 Conclusions

Based on the results of the SI, no relevant compounds were detected in soil. PFOA, PFBS, 

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

There were no exceedances of the SLs in soil or groundwater, and no further evaluation at AOI 2

is warranted.

6.5 BOUNDARY SAMPLE LOCATIONS

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

samples collected at the Facility boundary. The detected compounds are summarized in Tables 

6-2 through 6-5. Soil and groundwater results are presented on Figures 6-1 through 6-7.
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6.5.1 Boundary Sample Locations – Soil Analytical Results

No soil samples were collected from boundary locations.

6.5.2 Boundary Sample Locations – Groundwater Analytical Results

Groundwater was sampled from two temporary monitoring wells AASF-01 and AASF-02

located at the northern boundary between the Facility and the Reno-Stead Airport. AASF-01 and 

AASF-02 are located upgradient of AOI 1 based on the regional groundwater flow direction. The

July 2022 groundwater elevations depicted radial groundwater flow direction ranging from north

to west to northwest (Figure 2-4), which places AASF-01 downgradient of AOI 1. PFOA, PFBS, 

and PFOS were detected at concentrations below their respective SLs. PFOS was detected at 

both AASF-01 and AASF-02 at concentrations of 0.55 J and 0.8 J ng/L, respectively. PFOA was 

detected at AASF-02 at a concentration of 0.54 J ng/L. PFBS were detected at AASF-02 at a 

concentration of 1.7 J ng/L. PFHxS and PFNA were not detected in the boundary groundwater 

samples.

6.5.3 Conclusions

Based on the results of the SI, PFOA, PFBS, and PFOS were detected in boundary groundwater 

samples at concentrations below their respective SLs.
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Table 6-2

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

Site Inspection Report, Reno Army Aviation Support Facility, Nevada

Analyte OSD Screening 

Level 1 Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual

Soil, PFAS by LC/MS/MS compliant with QSM Version 5.3 Table B-15 (μg/kg)

PFBS 1,900 ND ND ND ND ND ND

PFHxS 130 ND ND 0.32 J 0.36 J ND ND

PFNA 19 ND ND ND ND ND ND

PFOS 13 ND ND 11 1.3 ND ND

PFOA 19 ND ND ND 0.25 J ND ND

Gray Fill Detected concentration exceeded OSD Screening Level Chemical Abbreviations

PFBS Perfluorobutanesulfonic acid 

References PFHxS Perfluorohexanesulfonic acid 

1. Assistant Secretary of Defense, July 2022. Risk Based Screening Levels Calculated PFNA Perfluorononanoic acid 

 for PFOA, PFOS, PFBS, PFHxS, and PFNA in Groundwater or Soil using USEPA’s PFOS Perfluorooctanesulfonic acid 

Regional Screening Level Calculator. HQ=0.1. May 2022. The screening levels for soil are PFOA Perfluorooctanoic acid 

 based on residential scenario for incidental ingestion of contaminated soil.

Acronyms and Abbreviations

AOI Area of Interest

Interpreted Qualifiers ft Feet

J = Estimated concentration ND analyte not detected above the LOD (LOD values are prented in Appendix E)

LOD limit of detection

OSD Office of the Secretary of Defense

PFAS per- and polyfluoralkyl substances

QSM Quality Systems Manual

Qual interpreted qualifier

μg/kg micrograms/kilogram

Sample Date

Depth (ft) 1-2 1-2 1-2 0-2

7/15/2022 7/15/2022 7/14/2022 7/7/2022

AOI02-01-SB-0-2

Parent Sample ID

AOI 1 AOI 2

Sample Name AOI01-01-SB-1-2 AOI01-02-SB-1-2 AOI01-03-SB-1-2 AOI01-04-SB-0-2

Area of Interest 

Location ID AOI01-01 AOI01-02 AOI01-03 AOI01-04

AOI02-02-SB-7-8

AOI02-01 AOI02-02

7/12/2022 7/13/2022

0-2 7-8
Table 6-3

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

Site Inspection Report, Reno Army Aviation Support Facility, Nevada

Analyte OSD Screening 

Level 1 Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual

Soil, PFAS by LC/MS/MS compliant with QSM Version 5.3 Table B-15 (μg/kg)

PFBS 25000 ND ND ND 1.4 J ND ND ND ND

PFHxS 1600 ND ND ND 1.1 ND ND ND ND

PFNA 250 ND ND ND ND ND ND ND ND

PFOS 160 ND ND ND 2.1 J+ ND ND ND ND

PFOA 250 ND ND ND ND ND ND ND ND

Gray Fill Detected concentration exceeded OSD Screening Level Chemical Abbreviations

PFBS Perfluorobutanesulfonic acid 

References PFHxS Perfluorohexanesulfonic acid 

1. Assistant Secretary of Defense, July 2022. Risk Based Screening Levels Calculated PFNA Perfluorononanoic acid 

for PFOA, PFOS, PFBS, PFHxS, and PFNA in Groundwater or Soil using USEPA’s PFOS Perfluorooctanesulfonic acid 

Regional Screening Level Calculator. HQ=0.1. May 2022. The screening levels for soil PFOA Perfluorooctanoic acid 

are based on Industrial/Commercial Composite Worker scenario for incidental ingestion 

of contaminated soil. Acronyms and Abbreviations

AOI Area of Interest

Interpreted Qualifiers ft Feet

J = Estimated concentration LOD limit of detection

J+ = Estimated quantity but may bias high ND analyte not detected above the LOD

OSD Office of the Secretary of Defense

PFAS per- and polyfluoralkyl substances

QSM Quality Systems Manual

Qual interpreted qualifier

μg/kg micrograms/kilogram

AOI02-02

AOI 1

7/14/2022

14-15

AOI01-03-SB-14-15

Parent Sample ID AOI01-02-SB-14-15

Sample Name AOI01-01-SB-14-15 AOI01-02-SB-14-15 RENO-FD-02

Area of Interest 

Location ID AOI01-01 AOI01-02 AOI01-02 AOI01-03 AOI01-04 AOI02-01 AOI02-02

AOI 2

AOI01-04-SB-14-15 AOI02-01-SB-14-15 AOI02-02-SB-22-23 RENO-FD-01

AOI02-02-SB-22-23

7/8/2022 7/12/2022 7/13/2022

14-15 14-15 22-23 22-23

7/13/2022

Depth (ft) 14-15 14-15 14-15

Sample Date 7/18/2022 7/15/2022 7/15/2022
Table 6-4

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

Site Inspection Report, Reno Army Aviation Support Facility, Nevada

Analyte

OSD

Screening

Level

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

Soil, PFAS by LC/MS/MS compliant with QSM Version 5.3 Table B-15 (μg/kg)

PFBS -- ND ND ND ND ND ND

PFHxS -- ND ND ND ND ND ND

PFNA -- ND ND ND ND ND ND

PFOS -- ND ND 0.76 J+ ND ND ND

PFOA -- ND ND ND ND ND ND

Interpreted Qualifiers Chemical Abbreviations

J+ = Estimated quantity but may bias high PFHxS Perfluorohexanesulfonic acid

PFNA Perfluorononanoic acid

PFOS Perfluorooctanesulfonic acid

PFOA Perfluorooctanoic acid

Acronyms and Abbreviations

AOI Area of Interest

ft Feet

LOD limit of detection

ND analyte not detected above the LOD

OSD Office of the Secretary of Defense

PFAS per- and polyfluoralkyl substances

QSM Quality Systems Manual

Qual interpreted qualifier

μg/kg micrograms/kilogram

Area of Interest AOI 2

Location ID AOI01-01 AOI01-02 AOI01-03 AOI01-04 AOI02-01 AOI02-02

Sample Name AOI01-01-SB-50-51 AOI01-02-SB-50-51 AOI01-03-SB-45-46 AOI02-01-SB-55-56 AOI02-02-SB-63-64

50-51 45-46 55-56 63-64

7/15/2022 7/14/2022 7/8/2022 7/13/2022 7/13/2022

AOI 1

Sample Date 7/18/2022

Depth (ft) 50-51 44-45

Parent Sample ID

AOI01-04-SB-44-45
Table 6-5

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

Site Inspection Report, Reno Army Aviation Support Facility, Nevada

Analyte OSD Screening Level 1 Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual

PFBS 601 2.2 2.0 1.9 21 60 16 3.6 8.8 26 10 ND 1.7 J

PFHxS 39 4.4 0.93 J 0.98 J 54 29 5.7 3.0 22 8.9 3.3 ND ND

PFNA 6 ND ND ND 3.3 0.52 J ND 0.85 J ND ND ND ND ND

PFOS 4 3.1 2.5 2.4 67 10 6.1 10 3.8 J+ 0.84 J 2.8 0.55 J 0.80 J

PFOA 6 0.81 J 0.46 J ND 20 4.3 1.5 J 2.9 7.8 0.51 J 0.51 J ND 0.54 J

Notes

Grey Fill Detected concentration exceeded OSD Screening Levels

References

1. 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.

Interpreted Qualifiers

J = Estimated concentration

J+ = Estimated concentration, bias high.

7/20/2022 7/21/2022 7/21/2022 7/20/2022 7/20/2022 7/19/2022 7/20/2022

Parent Sample ID AOI01-02-GW

Sample Name AOI01-01-GW AOI01-02-GW RENO-FD-03 AOI01-03-GW AOI01-04-GW AASF-02-GW

AOI01-05 AOI01-06 AOI01-07 AASF-02

AOI01-05-GW AOI01-06-GW AOI01-07-GW AOI02-01-GW AOI02-02-GW AASF-01-GW

AOI02-01 AOI02-02 AASF-01

 PFAS by LC/MS/MS compliant with QSM Version 5.3 Table B-15 (ng/L)

Location ID AOI01-01 AOI01-02 AOI01-02 AOI01-03 AOI01-04

Sample Date 7/19/2022 7/18/2022 7/18/2022 7/15/2022 7/19/2022
Data Sources: 

ESRI 2020

AECOM 2020

Date.......May 2023

Prepared By:........WSP

Prepared For:...USACE

Facility Data

Facility Boundary

Area of Interest (AOI)

Potential PFAS Release

Army National Guard Site Inspections 

Site Inspection Report

Reno Army Aviation Support Facility 

Reno, Nevada

Figure 6-1

PFOS Detections in Soil 

) NV

!(

!(

!(

!(

!(

!(

AOI01-02

AOI01-03

AOI01-04

AOI02-01

AOI02-02

AOI01-01

!(

!(

!(

!(

!(

!(

AOI01-02

AOI01-03

AOI01-04

AOI02-01

AOI02-02

AOI01-01

!(

!(

!(

!(

!(

!(

AOI01-02

AOI01-03

AOI01-04

AOI02-01

AOI02-02

AOI01-01

0 400

Feet

0 400

Feet

0 400

Feet

Shallow Intermediate Deep 3

Hydrology/Hydrogeology

Inferred Groundwater Flow Direction

Surface Water Flow Direction

NOTES:

PFOS = perfluorooctanesulfonic acid

ND = Non-Detect

(μg/Kg) = Microgram(s) per Kilogram

Exceedances of The Office of the Secretary of Defense

(OSD) Screening Level (SL) are depicted with a yellow

halo.

PFOS Results (μg/kg)

!( ND (Non-Detect)

!( >ND - 13

!!( >13 -160

!!( >160 - 1,600

!!( >1,600
Site Inspection Report

Reno Army Aviation Support Facility, Nevada Version: FINAL

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

This page intentionally left blank
Data Sources: 

ESRI 2020

AECOM 2020

Date :...............May 2023

Prepared By:.............WSP

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

Facility Data

Facility Boundary

Area of Interest (AOI)

Potential PFAS Release

Army National Guard Site Inspections 

Site Inspection Report

Reno Army Aviation Support Facility 

Reno, Nevada

Figure 6-2

PFOA Detections in Soil 

) NV

!(

!(

!(

!(

!(

!(

AOI01-02

AOI01-03

AOI01-04

AOI02-01

AOI02-02

AOI01-01

!(

!(

!(

!(

!(

!(

AOI01-02

AOI01-03

AOI01-04

AOI02-01

AOI02-02

AOI01-01

!(

!(

!(

!(

!(

!(

AOI01-02

AOI01-03

AOI01-04

AOI02-01

AOI02-02

AOI01-01

0 400

Feet

0 400

Feet

0 400

Feet

Shallow Intermediate Deep 3

Hydrology/Hydrogeology

Inferred Groundwater Flow Direction

Surface Water Flow Direction

NOTES:

PFOA = perfluorooctanoic acid

ND = Non-Detect

(μg/Kg) = Microgram(s) per Kilogram

Exceedances of The Office of the Secretary of Defense

(OSD) Screening Level (SL) are depicted with a yellow

halo.

PFOA Results (μg/kg)

!( ND (Non-Detect)

!( >ND - 19

!!( >19 - 250

!!( >250 - 2,500

!!( >2,500
Site Inspection Report

Reno Army Aviation Support Facility, Nevada Version: FINAL

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

This page intentionally left blank
Data Sources: 

ESRI 2020

AECOM 2020

Date :...........May 2023

Prepared By:........WSP

Prepared For:....USACE

Facility Data

Facility Boundary

Area of Interest (AOI)

Potential PFAS Release

) NV

!(

!(

!(

!(

!(

!(

AOI01-02

AOI01-03

AOI01-04

AOI02-01

AOI02-02

AOI01-01

!(

!(

!(

!(

!(

!(

AOI01-02

AOI01-03

AOI01-04

AOI02-01

AOI02-02

AOI01-01

!(

!(

!(

!(

!(

!(

AOI01-02

AOI01-03

AOI01-04

AOI02-01

AOI02-02

AOI01-01

0 400

Feet

0 400

Feet

0 400

Feet

Shallow Intermediate Deep 3

Hydrology/Hydrogeology

Inferred Groundwater Flow Direction

Surface Water Flow Direction

NOTES:

PFBS = perfluorobutanesulfonic acid

ND = Non-Detect

(μg/Kg) = Microgram(s) per Kilogram

Exceedances of The Office of the Secretary of

Defense ( OSD) S creening L evel ( SL) a re

depicted with a yellow halo.

PFBS Results (μg/kg)

!( ND (Non-Detect)

!( >ND - 10

!( >10 - 1,900

!!( >1,900 - 25,000

!!( >25,000

Army National Guard Site Inspections

Site Inspection Report

Reno Army Aviation Support Facility 

Reno, Nevada

Figure 6-3

PFBS Detections in Soil 
Site Inspection Report

Reno Army Aviation Support Facility, Nevada Version: FINAL

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

This page intentionally left blank
Data Sources: 

ESRI 2020

AECOM 2020

Date:.....December 2023

Prepared By:...........WSP

Prepared For:......USACE

Facility Data

Facility Boundary

Area of Interest (AOI)

Potential PFAS Release

Army National Guard Site Inspections

Site Inspection Report

Reno Army Aviation Support Facility 

Reno, Nevada

Figure 6-4 

PFHxS Detections in Soil (AOI 1)

) NV

!(

!(

!(

!(

!(

!(

AOI01-02

AOI01-03

AOI01-04

AOI02-01

AOI02-02

AOI01-01

!(

!(

!(

!(

!(

!(

AOI01-02

AOI01-03

AOI01-04

AOI02-01

AOI02-02

AOI01-01

!(

!(

!(

!(

!(

!(

AOI01-02

AOI01-03

AOI01-04

AOI02-01

AOI02-02

AOI01-01

0 400

Feet

0 400

Feet

0 400

Feet

Shallow Intermediate Deep 3

Hydrology/Hydrogeology

Surface Water Flow Direction

Inferred Groundwater Flow Direction

NOTES:

PFHxS = perfluorohexanesulfonic acid

ND = Non-Detect

(μg/Kg) = Microgram(s) per Kilogram

Exceedances of The Office of the Secretary of Defense

(OSD) Screening Level (SL) are depicted with a yellow

halo.

PFHxS Results (μg/kg)

!( ND (Non-Detect)

!( >ND - 13

!( >13 -130

!!( >130 - 1,300

!!( >1,300
Site Inspection Report

Reno Army Aviation Support Facility, Nevada Version: FINAL

EA Engineering, Science, and Technology, Inc., PBC 6-18

This page intentionally left blank
Data Sources: 

ESRI 2020

AECOM 2020

Date :........May 2023

Prepared By:........WSP

Prepared For:..USACE

Facility Data

Facility Boundary

Area of Interest (AOI)

Potential PFAS Release

) NV

!(

!(

!(

!(

!(

!(

AOI01-02

AOI01-03

AOI01-04

AOI02-01

AOI02-02

AOI01-01

!(

!(

!(

!(

!(

!(

AOI01-02

AOI01-03

AOI01-04

AOI02-01

AOI02-02

AOI01-01

!(

!(

!(

!(

!(

!(

AOI01-02

AOI01-03

AOI01-04

AOI02-01

AOI02-02

AOI01-01

0 400

Feet

0 400

Feet

0 400

Feet

Shallow Intermediate Deep 3

Hydrology/Hydrogeology

Surface Water Flow Direction

Inferred Groundwater Flow Direction

NOTES:

PFNA = perfluorononanoic acid

ND = Non-Detect

(μg/Kg) = Microgram(s) per Kilogram

Exceedances of The Office of the Secretary of Defense (OSD)

Screening Level (SL) are depicted with a yellow halo.

PFNA Results (μg/kg)

!( ND (Non-Detect)

!( >ND - 19

!!( >19 - 250

!!( >250 - 2,500

!!( >2,500

Army National Guard Site Inspections

Site Inspection Report

Reno Army Aviation Support Facility 

Reno, Nevada

Figure 6-5

PFNA Detections in Soil 
Site Inspection Report

Reno Army Aviation Support Facility, Nevada Version: FINAL

EA Engineering, Science, and Technology, Inc., PBC 6-20

This page intentionally left blank
Data Sources: 

ESRI 2020

AECOM 2020

Date:...........................May 2023

Prepared By:........................WSP

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

Facility Data

Facility Boundary

Area of Interest (AOI)

Potential PFAS Release

Army National Guard Site Inspections

Site Inspection Report

Reno Army Aviation Support Facility 

Reno, Nevada

Figure 6-6

PFOA, PFOS, PFBS Detections in Groundwater

) NV

!(

!(

!(

!(

!!(

!(

!(

!(

!(

!(

!!(

AOI01-06

AASF-01

AASF-02

AOI01-02

AOI01-03

AOI01-04

AOI02-01

AOI02-02

AOI01-05

AOI01-01

AOI01-07

!!(

!(

!(

!(

!!(

!!(

!(

!(

!!(

!(

!(

AOI01-06

AASF-01

AASF-02

AOI01-02

AOI01-03

AOI01-04

AOI02-01

AOI02-02

AOI01-05 AOI01-01

AOI01-07

!(

!(

!(

!(

!(

!(

!(

!(

!(

!(

!(

AOI01-06

AASF-01

AASF-02

AOI01-02

AOI01-03

AOI01-04

AOI02-01

AOI02-02

AOI01-05

AOI01-01

AOI01-07

0 400

Feet

0 400

Feet

0 400

Feet

PFOA PFOS PFBS 3

Hydrology/Hydrogeology

Inferred Groundwater Flow Direction

Surface Water Flow Direction

NOTES:

PFOS = perfluorooctanesulfonic acid

PFOA = perfluorooctanoic acid

PFBS = perfluorobutanesulfonic acid

ND = non-detect

ng/L = nanogram(s) per liter

Exceedances of The Office of the Secretary of Defense

(OSD) Screening Level (SL) are depicted with a yellow halo

PFOA Results (ng/L)

!( ND (Non-Detect)

!( >ND - 6

!!( >6 - 40

!!( >40 - 70

!!( >70

PFOS Results (ng/L)

!( ND (Non-Detect)

!( >ND - 4

!!( >4 - 40

!!( >40 - 70

!!( >70

PFBS (ng/L)

!( >100 - 601

!( ND (Non-Detect)

!( >ND - 100

!!( >601 - 1,000

!!( >1,000
Site Inspection Report

Reno Army Aviation Support Facility, Nevada Version: FINAL

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

This page intentionally left blank
Data Sources: 

ESRI 2020

AECOM 2020

Date:............May 2023

Prepared By:...........WSP

Prepared For:......USACE

Facility Data

Facility Boundary

Area of Interest (AOI)

Potential PFAS Release

Army National Guard Site Inspections

Site Inspection Report

Reno Army Aviation Support Facility 

Reno, Nevada

Figure 6-7

PFHxS and PFNA Detections in Groundwater

) NV

!(

!(

!(

!(

!!(

!(

!(

!(

!(

!(

!(

AOI01-06

AASF-01

AASF-02

AOI01-02

AOI01-03

AOI01-04

AOI02-01

AOI02-02

AOI01-05

AOI01-01

AOI01-07

!(

!(

!(

!(

!(

!(

!(

!(

!(

!(

!(

AOI01-06

AASF-01

AASF-02

AOI01-02

AOI01-03

AOI01-04

AOI02-01

AOI02-02

AOI01-05

AOI01-01

AOI01-07

0 400

Feet

0 400

Feet

PFHxS PFNA 3

Hydrology/Hydrogeology

Inferred Groundwater Flow Direction

Surface Water Flow Direction

NOTES:

PFHxS = Perfluorohexanesulfonic acid

PFNA = Perfluorononanoic acid

ND = Non-Detect

ng/L = nanogram(s) per liter

Exceedances of The Office of the Secretary of Defense

(OSD) Screening Level (SL) are depicted with a yellow halo

PFHxS Results (ng/L)

!( ND (Non-Detect)

!( >ND - 39

!!( >39 - 100

!!( >100 - 1000

!!( >1,000

PFNA Results (ng/L)

!( ND (Non-Detect)

!( >ND - 6

!!( >6 - 100

!!( >100 - 1000

!!( >1000
Site Inspection Report

Reno Army Aviation Support Facility, Nevada Version: FINAL

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Site Inspection Report

Reno Army Aviation Support Facility, Nevada Version: FINAL

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

7. EXPOSURE PATHWAYS

The Conceptual Site Models (CSMs) for the AOIs, revised based on the SI findings, are 

presented on Figure 7-1 and 7-2. Please note that while the CSM discussion assists in 

determining if a receptor may be impacted, the decision to move from SI to RI or interim action 

is determined based upon exceedances of the SLs for the relevant compounds and whether the 

release is more than likely attributable to the DoD. A CSM presents the current understanding of 

the Facility conditions with respect to known and suspected sources, potential transport 

mechanisms and migration pathways, and potentially exposed human receptors. A human 

exposure pathway is considered potentially complete when the following conditions are present.

1. Contaminant source

2. Environmental fate and transport

3. Exposure point

4. Exposure route

5. Potentially exposed populations.

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

circle symbol to represent an incomplete exposure pathway. Areas with no identified complete 

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

complete if the relevant compounds are detected, in which case the CSM figure uses a half-filled 

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

filled circle symbol is used to indicate when a potentially complete exposure pathway has 

detections of the relevant compounds above the SLs. Areas with an identified potentially 

complete pathway and a complete pathway may warrant further investigation. Although the 

CSM indicates 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 EPA guidance for risk screening (EPA 2001). 

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

construction workers, trespassers, residents outside the Facility boundary, and recreational users 

outside of the Facility boundary.

7.1 SOIL EXPOSURE PATHWAY

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

between the source and potential receptors at each AOI based on the aforementioned criteria.
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7.1.1 AOI 1

AOI 1 is the Former Firetruck Bay and Rotary Wing Parking Area, where AFFF was historically 

stored and possibly used. No potential releases or AFFF usage was noted during the PA 

(AECOM, 2020) at AOI 1.

PFOA, PFBS, and PFOS were detected in the surface soil at AOI 1 at concentrations below their

respective SLs. Facility and construction workers and trespassers could contact constituents in 

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

pathway for Facility workers and construction workers are potentially complete. PFBS, PFOS, 

and PFHxS were detected in the subsurface soil at AOI 1 at concentrations below their respective 

SLs. Construction workers could contact constituents in subsurface soil during soil disturbing 

activities via incidental ingestion and inhalation of dust. Therefore, the subsurface soil exposure 

pathway for construction workers is potentially complete. The CSM for AOI 1 is presented on 

Figure 7-1.

7.1.2 AOI 2

AOI 2 is the stockpiled soils, where excavated soils from the tarmac improvements are stored. 

No potential releases were noted in this area during the PA (AECOM, 2020) at AOI 2.

PFOA, PFBS, PFOS, PFHxS, and PFNA were not detected in the surface or subsurface soils at 

AOI 2. Therefore, the surface and subsurface soil exposure pathways for Facility and 

construction workers and trespassers is incomplete. The CSM for AOI 2 is presented on Figure 

7-2.

7.2 GROUNDWATER EXPOSURE PATHWAY

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

exists between the source and potential receptors at each AOI based on the aforementioned 

criteria.

7.2.1 AOI 1

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

collected at AOI 1. PFBS and PFNA were detected below their respective SLs in groundwater 

samples collected at AOI 1. PFOA, PFOS, and PFBS were detected in groundwater at the 

Facility boundary at AOI 1 but at concentrations below their respective SLs. The Facility is 

secured therefore, the pathway for ingestion of shallow groundwater by a trespasser is 

incomplete.

The depth to static groundwater at AOI 1 observed in July 2022 during the SI ranged from 

approximately 41 to 51 ft bgs, which is below the anticipated limit of construction activities (15 

feet bgs). Therefore, the pathway for construction worker exposure to groundwater is 

incomplete.

Domestic wells were identified within a 2-mile radius potentially downgradient of the Facility 

(Figure 2-3). Drinking water for Reno AASF is supplied by the municipality. Two municipal 

wells were identified during the PA (AECOM, 2020) approximately 0.1-mile to the west of the 

Facility. The recharge/injection well and replacement public supply/recharge well are completed 
Site Inspection Report

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at depths of approximately 840 and 600 ft bgs, respectively. According to a TMWA Report on 

Aquifer Storage and Recovery provided by the ARNG (TMWA, 2020), the recharge/injection 

well is used for injection of treated surface water into the groundwater aquifer of the Truckee 

Meadows hydrographic basin as well as for water supply. A replacement public supply/recharge

well is also located proximal to the active well. The exposure pathway for ingestion is potentially 

complete for site workers and off-site residential receptors. The CSM for AOI 1 is presented on 

Figure 7-1.

7.2.2 AOI 2

PFOA, PFBS, PFOS, and PFHxS were detected in AOI 2 groundwater below their respective 

SLs. Depths to water measured at AOI 2 in July 2022 during the SI ranged from approximately 

54 to 60 ft bgs, which is below the anticipated limit of construction activities (15 feet bgs). 

Therefore, the pathway for construction worker exposure to groundwater is incomplete. The 

Facility is secured; therefore, the pathway for ingestion of shallow groundwater by a trespasser is 

incomplete. Domestic wells were identified within a 2-mile radius of the Facility (Figure 2-3);

therefore, the exposure pathway for ingestion is potentially complete for off-site residential 

receptors. Drinking water for Reno AASF is supplied by the municipality. Two municipal wells

were identified during the PA (AECOM, 2020) approximately 0.1-mile to the west of the 

Facility, the aforementioned TMWA Report (TMWA, 2020) indicates a municipal 

recharge/injection well and a replacement public supply/recharge well. According to a TMWA 

Report on Aquifer Storage and Recovery provided by the ARNG (TMWA, 2020), the 

recharge/injection well is used for injection of treated surface water into the groundwater aquifer 

of the Truckee Meadows hydrographic basin as well as for water supply. Therefore, the pathway 

for ingestion of shallow groundwater by a site worker and off-site resident is potentially 

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

7.3 SURFACE WATER AND SEDIMENT EXPOSURE PATHWAY

According to the Facility Storm Water Pollution Prevention Plan (SWPPP) (Reno-Tahoe Airport 

Authority. 2020) the Reno-Stead Airport is located within a topographically enclosed 

hydrographic area and there is no surface water outlet except through evaporation and 

infiltration. However, the SWPPP also references three primary stormwater discharge points and 

states that Swan/Lemmon Lake and Silver Lake (Figure 2-5) are surface waters that receive 

stormwater from the Facility. According to the Reno-Stead Airport Master Plan Update (PBSJ. 

2010) the eastern most portion of Reno-Stead Airport drains to the southeast of the Airport into 

Swan/Lemmon Lake, while the majority of the Reno-Stead Airport (including AOI 1 and AOI 2 

areas) drains to the south and southwest. The natural drainage ultimately empties into either 

Silver Lake to the southwest or Swan/Lemmon Lake to the southeast. SI results in soil and 

groundwater from AOI 1 and AOI 2, 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. PFOA, PFOS, and PFHxS were detected in surface soil at AOI 1. The sediment and 

surface water exposure pathway via the Facility and Airport stormwater systems, is considered 

potentially complete for construction workers. The sediment and surface water exposure pathway 

to site workers is considered incomplete, as no surface water bodies are located on the Facility. 
Site Inspection Report

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The Facility is secured and fenced, thus the surface water and sediment exposure pathway to 

trespassers is considered incomplete. Although Silver Lake is located approximately 3 to 4 miles 

from the Facility, stormwater may eventually enter the Lake; thus, the surface water and 

sediment exposure pathway for residents is considered potentially complete via incidental 

ingestion during recreation. No relevant compounds were detected in surface soil at AOI 2, and 

all pathways for surface water and sediment are considered incomplete for AOI 2.
Notes:

1. The resident and recreational users refer to

off-site receptors.

Figure 7-1 Conceptual 

Site Model

AOI 1 Reno AASF

RECEPTOR

Human Receptors:

Current/Future

Site 

Worker

Construction 

Worker Resident1 Trespasser

Site 

Worker Construction 

Worker Resident 1

Trespasser

AOI 1 PFAS in 

Surface Soil 

and Paved 

Tarmac/ 

Parking 

Apron

Human 

Activities

Precipitation/

Run-Off

Leaching/

Infiltration

Airborne 

Soil 

Particulate

Surface Soil 

at AOI

Surface 

Water/ 

Sediment

Subsurfac

e Soil

Shallow 

Groundwater

Ingestion

Ingestion

Ingestion

Ingestion

Potential 

Off-Facility 

Source 

Not under 

Control of 

ARNG

Crash Firetruck, 

AFFF Fire 

Protection 

System, HandTruck Fire 

Extinguishers, 

and Fire 

Extinguisher 

Storage

SOURCE

Source Release 

Mechanism Media

PATHWAY

Transport

and Migration Media Exposure 

Routes

Inhalation 

of Dust

LEGEND

Flow-Chart Stops

Flow-Chart Continues

Partial / Possible Flow

Incomplete Pathway

Potentially Complete Pathway

Potentially Complete Pathway with 

Exceedance of Screening Level
Site Inspection Report

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Notes:

1. The resident and recreational users refer to

off-site receptors.

Figure 7-2

Conceptual Site Model

AOI 2 Reno AASF

RECEPTOR

Human Receptors:

Current/Future

Site 

Worker

Construction 

Worker Resident1 Trespasser

Site 

Worker Construction 

Worker Resident 1

Trespasser

AOI 2 PFAS in 

Surface 

Soil and 

Excavate

d Soils

Human 

Activities

Precipitation/

Run-Off

Leaching/

Infiltration

Airborne 

Soil 

Particulate

Surface Soil 

at AOI

Surface 

Water/ 

Sediment

Subsurfac

e Soil

Shallow 

Groundwater

Ingestion

Ingestion

Ingestion

Ingestion

Potential 

Off-Facility 

Source 

Not under 

Control of 

ARNG

Stockpiled 

Soils from 

the Site 

Improvement

s Associated 

with Tarmac 

SOURCE

Source Release 

Mechanism Media

PATHWAY

Transport

and Migration Media Exposure 

Routes

Inhalation 

of Dust

LEGEND

Flow-Chart Stops

Flow-Chart Continues

Partial / Possible Flow

Incomplete Pathway

Potentially Complete Pathway

Potentially Complete Pathway with 

Exceedance of Screening Level
Site Inspection Report

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Site Inspection Report

Reno Army Aviation Support Facility, Nevada Version: FINAL

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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 on 14 April 2022 and from 5 to 22 July 2022. The SI field 

activities included soil and groundwater sampling. Field activities were conducted in accordance 

with the UFP-QAPP Addendum (EA/Wood, 2022a), except as previously noted in Section 5.8.

To fulfill the project DQOs set forth in the approved SI UFP-QAPP Addendum (EA/Wood,

2021), samples were collected and analyzed for a subset of PFAS by LC/MS/MS compliant with 

QSM 5.3 Table B-15 as follows.

• 18 soil grab samples from 6 boring locations

• 11 grab groundwater samples from 11 temporary well locations

• 21 QA/QC samples.

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

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

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

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

required. Additionally, the CSMs were refined to assess whether a potentially complete pathway 

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

described in Section 7.

8.2 OUTCOME

Based on the results of this SI, further evaluation under CERCLA is warranted for AOI 1, and no 

further action is warranted at this time at AOI 2. Based on the CSMs developed and revised 

based on the SI findings, there is potential for exposure to 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. The following bullets summarize the SI 

results relative to the SLs:

At AOI 1:

• In the surface soils, PFOS, PFOA, and PFHxS were detected in soil at concentrations less

than the respective SLs. PFOS and PFHxS were detected at AOI01-03 and PFOA, PFOS, and

PFHxS were detected at AOI01-04. The maximum PFOA concentration in soil was 0.25 J

μg/kg. The maximum PFOS concentration in soil was 11 μg/kg. The maximum PFHxS

concentration in soil was 0.36 J μg/kg.
Site Inspection Report

Reno Army Aviation Support Facility, Nevada Version: FINAL

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• In the subsurface soils, PFBS, PFOS, and PFHxS were detected at AOI01-03 at 

concentrations below SLs. The maximum PFBS concentration in soil was 1.4 J μg/kg. The 

maximum PFOS concentration in soil was 2.1 J+ μg/kg. The maximum PFHxS concentration 

in soil was 1.1 μg/kg.

• In groundwater, PFOA, PFOS, and PFHxS were detected at concentrations exceeding the 

SLs at AOI01-03. Detections of PFOA in groundwater exceeded SLs at AOI01-07, and 

PFOS was detected in groundwater at AOI01-04, AOI01-05, and AOI01-06 at concentrations 

that exceed SLs. The maximum concentrations of PFOA, PFOS, and PFHxS in groundwater 

were 20 ng/L, 67 ng/L, and 54 ng/L, respectively.

• PFBS and PFNA were detected in groundwater at AOI 1 at concentrations below the SLs.

• PFOA, PFBS, and PFOS were detected in groundwater at AASF-02 at concentrations of 0.54 

J ng/L, 1.7 J ng/L, and 0.8 J ng/L, respectively, and PFOS was detected at AASF-01 at a 

concentration of 0.55 J. Detections of all relevant compounds at AASF-01 and AASF-02 

were below their respective SLs.

• Based on the results of the SI, further evaluation of AOI 1 is warranted.

At AOI 2:

• No relevant compounds (PFOA, PFBS, PFOS, PFHxS, and PFNA) were detected at AOI 

2 in the surface soils or subsurface soils.

• PFOA, PFBS, PFOS, and PFHxS were detected in groundwater at AOI02-01 and AOI02-

02 at concentrations that did not exceed the SLs. The maximum PFOA concentration in 

groundwater was 0.51 J ng/L. The maximum PFBS concentration in groundwater was 26

ng/L. The maximum PFOS concentration in groundwater was 2.8 ng/L. The maximum 

PFHxS concentration in groundwater was 8.9 ng/L.

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

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

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

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

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

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

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

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

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. 
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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

Former Firetruck Bay

and Rotary Wing 

Parking Area

Proceed to 

Remedial 

Investigation

2 Stockpiled Soils No further Action

Legend:

 = Detected; exceedance of screening levels

 = Detected; no exceedance of screening levels

= Not detected
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