FINAL

Site Inspection Report 

Orchard Combat Training Center

Boise, Idaho

Site Inspection for Perfluorooctanoic acid (PFOA), 

Perfluorooctanesulfonic acid (PFOS), Perfluorohexanesulfonic 

acid (PFHxS), Perfluorononanoic acid (PFNA), 

Hexafluoropropylene oxide dimer acid (HFPO-DA), and 

Perfluorobutanesulfonic acid (PFBS) at ARNG Installations, 

Nationwide

May 2023

Prepared for:

Army National Guard Bureau

111 S. George Mason Drive

Arlington, VA 22204

UNCLASSIFIED
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Table of Contents

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

3.1 AOI 1 Range 2 FTA...............................................................................................3-1

3.2 AOI 2 OCTC Fire Station.......................................................................................3-1

3.3 AOI 3 Wastewater Lagoons...................................................................................3-2

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

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

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

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

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

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

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

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

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

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

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

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

5.3 Production Well Sampling .....................................................................................5-3

5.4 Sediment Sampling ...............................................................................................5-4

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

5.6 Surveying..............................................................................................................5-4

5.7 Investigation-Derived Waste..................................................................................5-5

5.8 Laboratory Analytical Methods ..............................................................................5-5

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

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

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

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

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

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

6.3.2 AOI 1 Conclusions ......................................................................................6-2

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

6.4.2 AOI 2 Conclusions ......................................................................................6-3

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

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

6.5.2 AOI 3 Sediment Analytical Results ..............................................................6-4

6.5.3 AOI 3 Conclusions ......................................................................................6-4

6.6 Production Wells ...................................................................................................6-4

6.6.1 Groundwater Analytical Results...................................................................6-4

6.6.2 Production Wells Conclusions .....................................................................6-4

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

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

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

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

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

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

7.2.1 Production Wells .........................................................................................7-2

7.3 Sediment Exposure Pathway ................................................................................7-3

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

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

7.3.3 AOI 3...........................................................................................................7-3

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

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

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

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

Appendix A Data Usability Assessment and Validation Reports

Appendix B Field Documentation

B1. Log of Daily Notice of Field Activities

B2. Sampling Forms

B3. Field Change Request

B4. Survey Data

B5. Investigation-Derived Waste Location

Appendix C Photographic Log

Appendix D TPP Meeting Minutes

Appendix E Boring Logs

Appendix F Analytical Results

Appendix G Laboratory Reports

Figures

Figure 2-1 Facility Location

Figure 2-2 Facility Topography

Figure 2-3 Groundwater Features

Figure 2-4 Groundwater Elevations

Figure 2-5 Surface Water Features

Figure 3-1 Areas of Interest

Figure 5-1 Site Inspection Sample Locations

Figure 6-1 PFOA Detections in Soil, AOI 1

Figure 6-2 PFOA Detections in Soil, AOI 2

Figure 6-3 PFOA Detections in Soil, AOI 3

Figure 6-4 PFOS Detections in Soil, AOI 1

Figure 6-5 PFOS Detections in Soil, AOI 2

Figure 6-6 PFOS Detections in Soil, AOI 3

Figure 6-7 PFBS Detections in Soil, AOI 1

Figure 6-8 PFBS Detections in Soil, AOI 2

Figure 6-9 PFBS Detections in Soil, AOI 3

Figure 6-10 PFHxS Detections in Soil, AOI 1

Figure 6-11 PFHxS Detections in Soil, AOI 2

Figure 6-12 PFHxS Detections in Soil, AOI 3

Figure 6-13 PFNA Detections in Soil, AOI 1

Figure 6-14 PFNA Detections in Soil, AOI 2

Figure 6-15 PFNA Detections in Soil, AOI 3

Figure 6-16 PFOA Detections in Production Wells

Figure 6-17 PFOS Detections in Production Wells

Figure 6-18 PFBS Detections in Production Wells

Figure 6-19 PFHxS Detections in Production Wells

Figure 6-20 PFNA Detections in Production Wells

Figure 6-21 PFOA, PFOS, and PFBS Detections in Sediment

Figure 6-22 PFHxS and PFNA Detections in Sediment

Figure 7-1 Conceptual Site Model, AOI 1

Figure 7-2 Conceptual Site Model, AOI 2

Figure 7-3 Conceptual Site Model, AOI 3
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Tables

Table ES-1 Screening Levels (Soil and Groundwater)

Table ES-2 Summary of Site Inspection Findings and Recommendations

Table 5-1 Site Inspection Samples by Medium

Table 5-2 Soil Boring Depths

Table 5-3 Production Well Screen Intervals and Groundwater Elevations

Table 6-1 Screening Levels (Soil and Groundwater)

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

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

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

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

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

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

% percent

°C degrees Celsius

°F degrees Fahrenheit

μg/kg micrograms per kilogram

AECOM AECOM Technical Services, Inc.

AFFF aqueous film-forming foam

AOI Area of Interest

ARNG Army National Guard

bgs below ground surface 

BLM Bureau of Land Management

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act 

CoC chain of custody

CSM conceptual site model

DA Department of the Army

DoD Department of Defense

DOT Department of Transportation

DPT direct-push technology

DQO data quality objective

DUA data usability assessment

ELAP Environmental Laboratory Accreditation Program

EM Engineer Manual

EMO Environmental Management Office

FedEx Federal Express

FTA Fire Training Area

gpm gallons per minute

GPRS Ground Penetrating Radar Services, LLC.

GPS global positioning system

HA Health Advisory

HDPE high-density polyethylene 

HFPO-DA hexafluoropropylene oxide dimer acid

IDARNG Idaho Army National Guard

IDNG Idaho National Guard

IDW investigation-derived waste

IDWR Idaho Department of Water Resources

ITRC Interstate Technology Regulatory Council

LC/MS/MS liquid chromatography with tandem mass spectrometry

MATES Maneuver Area Training Equipment Site

MIL-SPEC military specification

MS matrix spike

MSD matrix spike duplicate

NELAP National Environmental Laboratory Accreditation Program

ng/L nanograms per liter

NOAA National Oceanic and Atmospheric Administration
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OCTC Orchard Combat Training Center

OSD Office of the Secretary of Defense

PA Preliminary Assessment

PFAS per- and polyfluoroalkyl substances

PFBS perfluorobutanesulfonic acid

PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

PID photoionization detector

PQAPP Programmatic UFP-QAPP

QA quality assurance

QAPP Quality Assurance Project Plan

QC quality control

QSM Quality Systems Manual

RI Remedial Investigation

SI Site Inspection

SL screening level

SOP standard operating procedure

SRTF Snake River Training Facility

TOC total organic carbon

TPP Technical Project Planning

UFP Uniform Federal Policy

US United States

USACE United States Army Corps of Engineers

USCS Unified Soil Classification System

USGS United States Geological Survey

USEPA United States Environmental Protection Agency

USFWS United States Fish and Wildlife Service
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Orchard Combat Training Center, Boise, Idaho

AECOM ES-1

Executive Summary

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

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

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

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

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

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

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

, and perfluorobutanesulfonic acid 

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

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

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

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

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

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

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

compounds. This SI was completed at the Orchard Combat Training Center (OCTC) in Boise, 

Idaho and determined no further investigation is warranted at AOI 1, AOI 2 or AOI 3, at this time. 

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

The OCTC is a 143,307-acre training facility located approximately 13 miles south of Boise, Idaho. 

The OCTC is publicly owned and is used for military training by Idaho ARNG (IDARNG), livestock 

grazing, and public recreation (Idaho National Guard Environmental Management Office, 2013). 

The majority of IDARNG training activities are conducted at the facility. About 41,000 acres of the 

facility are designated as Impact Area, while the remaining approximate 102,000 acres are used 

for training maneuvers. The training activities are mainly conducted to ensure military readiness.

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

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

Based on the results of this SI, further evaluation under CERCLA is not warranted in a Remedial 

Investigation for all three AOIs.

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

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

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

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

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

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

Analyteb

Residential

(Soil)

(μg/kg)a 

0-2 feet bgs

Industrial/ Commercial 

Composite Worker

(Soil)

(μg/kg)a 

2-15 feet bgs

Tap Water

(Groundwater)

(ng/L)a

PFOA 19 250 6

PFOS 13 160 4 

PFBS 1,900 25,000 601 

PFHxS 130 1,600 39

PFNA 19 250 6

Notes:

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

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

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

present.

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

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

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

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

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

AOI Potential 

Release Area

Soil –

Source 

Area

Groundwater – 

Source Area

Groundwater – 

Facility Boundary

Future 

Action

1 Range 2 FTA NA

No 

further 

action

2 OCTC Fire 

Station NA

No 

further 

action

3 Wastewater 

Lagoons NA

No 

further 

action

Production 

Wells SRTF-1 Unknown

No 

further 

action

Legend:

N/A = not applicable 

= detected; exceedance of the screening levels

= detected; no exceedance of the screening levels

= not detected

SRTF = Snake River Training Facility
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Orchard Combat Training Center, Boise, Idaho

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1. Introduction

1.1 Project Authorization

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

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

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

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

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

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

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

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

, and perfluorobutanesulfonic 

acid (PFBS) at ARNG facilities nationwide. The ARNG performed this SI at the Orchard Combat 

Training Center (OCTC) in Boise, Idaho. The OCTC is also referred to as the “facility” throughout 

this document. 

The SI project elements were performed in compliance with Comprehensive Environmental 

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

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

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

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

investigations.

1.2 SI Purpose

A PA was performed at OCTC (AECOM Technical Services, Inc. [AECOM], 2020) that identified 

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

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

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

investigation is warranted, a removal action is required to address immediate threats, or no further

action is required based on screening levels (SLs) for the relevant compounds.

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

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

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

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

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

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

2.1 Facility Location and Description

The OCTC is a 143,307-acre training facility located approximately 13 miles south of Boise, Idaho 

(Figure 2-1). The OCTC is used as a training area by the Idaho ARNG (IDARNG), as authorized 

under Public Law 103-64 and the 2010 OCTC Memorandum of Understanding between IDARNG 

and the Bureau of Land Management (BLM) and Idaho Military Division (IDARNG, 2018). The 

land remains publicly owned, and since 1953, it has been used for military training (by IDARNG), 

livestock grazing, and public recreation (Idaho National Guard [IDNG] Environmental 

Management Office [EMO], 2013).

The majority of IDARNG training activities are conducted at the facility. About 41,000 acres of the 

facility are designated as Impact Area, while the remaining approximate 102,000 acres are used 

for training maneuvers. The Impact Area is used for functioning ammunition, designated artillery, 

and mortar firing, and it is off-limits to the public. The training activities are mainly conducted to 

ensure military readiness.

2.2 Facility Environmental Setting

The OCTC is within the Snake River Valley, and the ground surface is characterized by low-rolling 

hills. The landscape has scarce vegetation, with all plants generally under 3 feet tall and no tree 

species. The facility is also located entirely within the Morley Nelson Snake River Birds of Prey 

National Conservation Area. No wetlands or permanent surface water bodies exist at the OCTC 

(IDNG EMO, 2013). Facility topography is shown on Figure 2-2.

2.2.1 Geology

The OCTC lies within the western portion of the Snake River Plain, which is a fault-bounded basin 

filled by volcanic flows and lakebed sediments that compose the Idaho Group (US Geological 

Survey [USGS], 1992). The Snake River runs through a deep gorge to the south of the OCTC.

The OCTC is almost entirely located within surficial Quaternary basalt deposits of the Snake River 

Group (Figure 2-3). Basalt ridges, buttes, cinder cones, and lava tubes punctuate the low-rolling 

hills that define the OCTC. Elevations at the facility range from 3,000 to 3,500 feet above mean 

sea level. The basalt is generally overlain by 0 to 10 feet of alluvium or wind-blown sedimentary 

deposits. The young basalt deposits of the Snake River Group are generally 500–1,000 feet thick 

under the facility. Below the Snake River Group lies the Idaho Group of Tertiary to Quaternary 

age, which is comprised of subaerial and lacustrine sedimentary deposits and basalt deposits 

(USGS, 1992). Although the Snake River Plain is bounded by faults, there is no evidence of major 

faulting within the OCTC (Boise State University & IDARNG, 2013).

Soil borings completed during the SI found soils dominated by fine-grained material with varying 

amounts of coarse-grained material, such as sand and gravel, overlying shallow basaltic bedrock

at OCTC. Depth to bedrock ranged from as shallow as approximately 2 feet bgs to beyond 21.5 

feet bgs. Borings were completed at depths between 2 and 21.5 feet bgs. These results and 

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

Boring logs are presented in Appendix E.
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2.2.2 Hydrogeology

Regionally, the water table can be deeper than 800 feet below ground surface (bgs); however, 

identified onsite supply wells range in total depths from 557 to 963 feet bgs. In general, regional 

groundwater flows to the southwest, towards the Snake River.

Wells drilled in the basalt deposits of the Snake River Group have some of the highest yields 

found in the country. Yields of 2,000 to 3,000 gallons per minute (gpm) are common, and some 

wells with production as high as 7,000 gpm have been observed. In general, transmissivity of the 

Snake River Group basalt packages is much higher than the transmissivity of the adjacent alluvial 

deposits (USGS, 1992).

Water movement in the young basalt aquifer is highly dependent on the heterogeneity of these 

volcanic deposits. Water flows horizontally through porous and permeable interflow zones in the 

basalt aquifers. An interflow zone consists of highly fractured vesicular basalt and cinders that 

compose the top part of one flow and the base of the overlying flow. Horizontal water movement 

can be several orders of magnitude higher in these zones than in other parts of the basalt aquifer. 

Water also moves vertically along joints and faults, and the direction is dependent upon the 

degree of jointing and fracturing in the rock. Layers of dense basalt with extremely low hydraulic 

conductivity may act as localized confining units in some areas and cause anomalous water levels 

(USGS, 1992). Localized groundwater flow paths at the OCTC are not well understood; however, 

groundwater in the Snake River Valley area generally flows south towards the Snake River 

(USGS, 1996).

The facility draws drinking water primarily from two production wells in the Cantonment area. The 

Idaho Department of Water Resources (IDWR) well registry lists these two wells at total depths 

of 755 feet and 753 feet (IDWR, 2019); static water levels for the two wells at the time of drilling 

were recorded at 491 feet and 479 feet. According to the driller’s logs, both of these wells are 

partially screened in volcanic deposits and in underlying fluvial or lacustrine sediments (IDWR, 

2019). Four additional potable water wells are located throughout OCTC, as shown on Figure 

2-3, that are inferred to be down or cross-gradient of the Cantonment area, at distances ranging 

from 0.75 to 11.5 miles.

Downgradient of the facility, multiple wells of ‘other/unknown’ use and one domestic well are 

located within 6 miles of the facility boundary. Only one well, which is listed as ‘other/unknown’ 

use, is located within 1-mile downgradient of the facility boundary. Wells with domestic, public 

supply, industrial, irrigation, and other/unknown uses are located outside of the facility’s northeast 

boundary, which is upgradient of the groundwater flow direction (Figure 2-3).

Depths to water measured in July 2021 during the SI at OCTC ranged from 423.2 to 775 feet bgs. 

Groundwater elevations and inferred groundwater flow directions from the SI are presented on 

Figure 2-4 and indicate the general groundwater flow direction is generally to the west/southwest, 

which is consistent with prior studies in the region (USGS, 1992 and 1996). However, groundwater 

in the vicinity of the cantonment appears to flow toward the west/northwest. The inconsistent 

groundwater flow direction may be attributed to a depression near the cantonment, screening 

intervals of the wells (i.e., not located within the same water bearing units), or well pumping 

occurring simultaneous to the gauging event.

2.2.3 Hydrology

The OCTC lies within the Snake River watershed, which is broken up into a number of smaller 

watersheds within the facility boundaries (Figure 2-5). The Snake River runs to the south and 

southwest of the facility; however, the OCTC has a very high rate of infiltration and no major 

surface water features. A few intermittent streams run for only a few hours four to five times per 

year during major storm events. Groundwater is generally 300–600 feet bgs or deeper in the 
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AECOM 2-3

OCTC area. Some surface water is held in playa lake beds in the spring, but the playas are 

typically dry by May or June (IDNG EMO, 2013).

2.2.4 Climate

The OCTC is characterized by a semiarid climate. Mean annual temperatures in the area are 

approximately 52.3 degrees Fahrenheit (°F), with an average winter low of 33.1° F and an average 

summer high of 73.6° F (National Oceanic and Atmospheric Administration [NOAA], 2022). The 

Boise Mountains to the northeast and the Owyhee Mountains to the southwest greatly influence 

precipitation events on the Snake River Plain. The OCTC is divided in half by the rain shadow of 

the Owyhee Mountains. As a result, the southern half of the OCTC has historically received annual 

precipitation of 5-8 inches, while the northern half of OCTC has historically received annual 

precipitation of 7-12 inches (IDNG EMO, 2013). Due to the climate, land use activities, and scarce 

vegetation, wind erosion is common in the summer months.

2.2.5 Current and Future Land Use

At present, the OCTC operates on a total land area of 143,000 acres. Cantonment and general 

support facilities for OCTC operations are in the area adjacent to the Maneuver Area Training 

Equipment Site (MATES) facility. The IDARNG Headquarters is at Gowen Field, which is colocated with the Boise Airport. The mission of the OCTC is to provide training lands and Annual 

Training facilities primarily to the ARNG and Reserve Forces as well as to other government and 

civilian organizations when possible (IDNG EMO, 2013).

The OCTC is the primary training area for IDARNG-assigned units, and it is one of the largest 

heavy force training areas for the National Guard. The Impact Area portion of the facility is closed 

to the public; however, the remainder of the OCTC is open to the public for grazing, hunting, offroad vehicle activity, and other recreational uses as approved by the BLM (IDNG EMO, 2013). 

Land use at the OCTC is not expected to change in the foreseeable future.

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 insects, snails, birds, and plants are federally endangered, threatened, proposed, 

and/ or are listed as candidate species in Ada County, Idaho (US Fish and Wildlife Service 

[USFWS], 2022). 

• Insects: Monarch butterfly, Danaus plexippus (candidate)

• Snails: Snake River physa snail, Physa natricina (endangered)

• Birds: Yellow-billed cuckoo, Coccyzus americanus (threatened)

• Flowering plants: Slickspot peppergrass, Lepidium papilliferum (threatened).

2.3 History of PFAS Use

Three potential release areas were identified at OCTC during the PA where AFFF may have been 

used or released historically (AECOM, 2020). Between 2014 and 2015, the Range 2 Fire Training 

Area (FTA) was used to practice extinguishing controlled burns with water and AFFF. The OCTC 

Fire Station houses an AFFF-equipped firetruck and historically stored firefighting backpacks. 

Nozzle testing and foam proportion testing were also conducted at the OCTC Fire Station 
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between 2013 and 2017. Sanitary and stormwater sewer systems at the facility discharge to the 

Wastewater Lagoons. The potential release areas were grouped into three AOIs based on 

proximity to one another and presumed groundwater flow. A description of each AOI is presented 

in Section 3.
CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

JH

8/3/2022

8/3/2022

Site Inspection at Ochard Combat Training Center, ID

1:633,600

8/3/2022 ­ Figure 2-1 PM CM 8/3/2022

12420 Milestone Center Drive

Germantown, MD 20876

Facility Location

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

increment P Corp., GEBCO, USGS, FAO, NPS, NRCAN,

Legend

Facility Boundary

0 5 10 20

Miles

Orchard Combat 

Training Center

^_

Cantonment Area

PROJECT

AECOM 2-5
CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

JH

8/3/2022

8/3/2022

Site Inspection at Ochard Combat Training Center, ID

1:190,080

8/3/2022 ­ Figure 2-2 PM CM 8/3/2022

12420 Milestone Center Drive

Germantown, MD 20876

Facility Topography

Base Map: Copyright:© 2013 National Geographic

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Figure 2-3

CLIENT

REVISED

SCALE

8/3/2022 MS

JH

8/3/2022

8/3/2022

ARNG

GIS BY

CHK BY

TITLE

Site Inspection at Ochard Combat Training Center, ID

PM CM 8/3/2022

1:316,800 ­ 12420 Milestone Center Drive

Germantown, MD 20876

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

PROJECT

AECOM 2-7
Site Inspection Report

Orchard Combat Training Center, Boise, Idaho

THIS PAGE INTENTIONALLY BLANK

AECOM 
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Figure 2-4

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Ochard Combat Training Center, ID

1/4/2023

1/4/2023

1/4/2023

MS

CH

CM

GIS BY

CHK BY

PM

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

1/4/2023

Groundwater Elevations

12420 Milestone Center Drive

Germantown, MD 20876

Legend

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PROJECT

AECOM 2-9
Site Inspection Report

Orchard Combat Training Center, Boise, Idaho

THIS PAGE INTENTIONALLY BLANK

AECOM 2-10
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CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

JH

8/3/2022

8/3/2022

Site Inspection at Ochard Combat Training Center, ID

1:180,349

8/3/2022 ­ Figure 2-5 PM CM 8/3/2022

12420 Milestone Center Drive

Germantown, MD 20876

Surface Water Features

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

and the GIS User Community

Legend

Facility Boundary

Water Body

River/Stream

Canal/Ditch

Pipeline

Surface Water Flow Direction

0 1.5 3 6

Miles

PROJECT

AECOM 2-11
Site Inspection Report

Orchard Combat Training Center, Boise, Idaho

AECOM 2-12

THIS PAGE INTENTIONALLY BLANK
Site Inspection Report

Orchard Combat Training Center, Boise, Idaho

AECOM 3-1

3. Summary of Areas of Interest 

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

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

identified at OCTC and grouped into three AOIs (AECOM, 2020). The potential release areas are 

shown on Figure 3-1.

3.1 AOI 1 Range 2 FTA

The Range 2 FTA consists of an area used to conduct controlled burns of vehicles. Cars were 

burned on three to six occasions at this area from 2014 to 2015. Each training session included 

the use of water to suppress the flames three times, followed by the use of an unknown quantity 

of 3 percent (%) AFFF foam to suppress the flames one time. The AFFF was allowed to dissipate 

and infiltrate into the soil at the FTA. During the SI, however, there was a dispute on the location 

of fire train exercises in this area. Based on discussions with fire station personnel, the general 

location of the training exercises was determined to be within the parking area for Range 2, 

approximately 0.25 miles south of the location identified during the PA. The approximate 

geographic coordinates of the Range 2 FTA, as determined during the PA, are 43°16'25.7" N; 

116°09'06.5" W.

3.2 AOI 2 OCTC Fire Station

The OCTC Fire Station is located on the western side of the MATES area; the geographic 

coordinates are 43°17'55.2" N; 116°03'47.0" W. The OCTC Fire Station was constructed between 

2012 and 2013, prior to which there was no fire department at the facility. At the time of the PA, 

about 20-30 gallons of 3% AFFF were stored on one firetruck at the OCTC Fire Station. No leaks 

or spills occurred from the time the fire department was established in 2013 to present, and the 

truck has never been used for emergency response. Additionally, four firefighting backpacks were 

historically stored at the OCTC Fire Station. Each unit included two bottles of 20 fluid ounces of 

Chemguard 3% AFFF, for a total of 160 fluid ounces of AFFF in bottled storage. These backpack 

units were issued to troops overseas to extinguish vehicle fires.

Historically, nozzle testing/foam proportion testing was conducted on more than one occasion 

outside the OCTC Fire Station, on the bare ground at two locations adjacent to the building, from 

2013 to 2017. The amount of foam used for each testing activity is estimated to have covered a 

25- by 25-foot area on the ground outside of the station. Figure 3-1 shows the approximate 

release areas. The exact volume of foam used during testing is unknown. On the northeast side 

of the building, foam that hit the ground infiltrated in the immediate vicinity. 

On the southwest side of the building, foam would have either infiltrated in the immediate vicinity 

or entered a grass ditch that runs along Orchard Access Road. Runoff that enters the ditch is 

directed into a grate that leads to below-grade pipes of the combined sanitary and stormwater 

sewer system. This system flows to the east into two lined wastewater lagoons, where water is 

left to evaporate. According to the PA, a system is in place that can direct excess water from the 

lagoons into a leach field; however, this system has never been used (AECOM, 2020). The use 

of foam for nozzle testing has ceased, and the fire department currently holds foam only for 

potential emergency responses.
Site Inspection Report

Orchard Combat Training Center, Boise, Idaho

AECOM 3-2

3.3 AOI 3 Wastewater Lagoons

The Wastewater Lagoons are located on the eastern side of the cantonment area; the geographic 

coordinates are 43°17’51’’ N; 116°03’19.5’’ W. Historical releases of AFFF at the OCTC Fire 

Station potentially entered the combined sanitary and stormwater sewer system. This system 

discharges to the Wastewater Lagoons; therefore, there is the potential for AFFF to have entered 

the lagoons. The ponds are lined, and water has never been discharged from them. Water that 

enters the south lagoon feeds into the north lagoon, and water is removed from the lagoon system 

through evaporation only.
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Site Inspection at Ochard Combat Training Center, ID

8/3/2022

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PROJECT

AECOM 3-3
Site Inspection Report

Orchard Combat Training Center, Boise, Idaho

THIS PAGE INTENTIONALLY BLANK

AECOM 3-4
Site Inspection Report

Orchard Combat Training Center, Boise, Idaho

AECOM 4-1

4. Project Data Quality Objectives

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

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

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

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

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

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

AOIs.

4.1 Problem Statement

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

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

SLs are presented in Section 6.1 of this report.

4.2 Information Inputs

Primary information inputs included:

• The PA for OCTC (AECOM, 2020);

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

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

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

parameters measured at the time of sampling.

4.3 Study Boundaries

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

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

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

owner(s). Temporal boundaries were limited to the summer season, which was the earliest available 

time field resources were available to complete the study.

4.4 Analytical Approach

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

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

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

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

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

4.5 Data Usability Assessment

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

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

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

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

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

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

Orchard Combat Training Center, Boise, Idaho

AECOM 4-2

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

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

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

requirements of the SI QAPP Addendum (AECOM, 2021a).
Site Inspection Report

Orchard Combat Training Center, Boise, Idaho

AECOM 5-1

5. Site Inspection Activities

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

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

in accordance with the following approved documents:

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

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

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

• Final Preliminary Assessment Report, Orchard Combat Training Center, Boise, Idaho dated 

February 2020 (AECOM, 2020);

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

Orchard Combat Training Center, Boise, Idaho dated May 2021 (AECOM, 2021a); and

• Final Site Safety and Health Plan, Orchard Combat Training Center dated July 2021

(AECOM, 2021b).

The SI field activities were conducted from 26 to 30 July 2021 and consisted of utility clearance, 

direct push boring, soil sample collection, sediment sample collection, pre-existing production well 

groundwater sample collection, and land surveying. Surveying of the production wells was 

completed 12 November 2021. Field activities were conducted in accordance with the SI QAPP 

Addendum (AECOM, 2021a), except as noted in Section 5.9.

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

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

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

• Twenty-eight (28) soil samples from 15 boring locations; 

• Six groundwater samples from six pre-existing production well locations; 

• Two sediment samples from two locations; and

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

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

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

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

in Appendix B1. Sampling forms are provided in Appendix B2, a Field Change Request Form 

is provided in Appendix B3, and land survey data are provided in Appendix B4, and 

investigation-derived waste (IDW) polygons are provided in Appendix B5. Additionally, a 

photographic log of field activities is provided in Appendix C.

5.1 Pre-Investigation Activities

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

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

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

5.1.1 Technical Project Planning

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

(USACE, 2016) defines four phases to project planning: 1.) defining the project phase; 2.) 
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Orchard Combat Training Center, Boise, Idaho

AECOM 5-2

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 15 March 2021, prior to SI field activities. The 

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

stakeholders for this SI include the ARNG, IDARNG, USACE, Idaho Department of Environmental 

Quality, Air National Guard, and representatives familiar with the facility, the regulations, and the 

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

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

combined TPP Meeting 1 and 2 was memorialized in the SI QAPP Addendum (AECOM, 2021a).

A TPP Meeting 3 was held after the field event to discuss the results of the SI. Meeting minutes 

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

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

5.1.2 Utility Clearance

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

DIGLINE, Inc. Idaho utility clearance provider to notify them of intrusive work. However, because 

OCTC is a private facility, the participating DIGLINE, Inc. locators did not clear utilities at the entire 

facility. Therefore, AECOM contracted Ground Penetrating Radar Services, LLC. (GPRS), a 

private utility location service, to perform utility clearance. GPRS performed utility clearance of 

the proposed boring locations on 28 July 2021 with input from the AECOM field team and OCTC 

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

clearance.

5.1.3 Source Water and Sampling Equipment Acceptability

PFAS-free ASTM Type II deionized water was purchased from Grainger and sampled on 27 July 

2021 to assess usability for decontamination of drilling equipment. Results of the sample collected 

from the Grainger provided PFAS-free ASTM Type II deionized water (OCTC-DECON-01) 

confirmed this source to be acceptable for use in this investigation; therefore, it was used 

throughout the field activities. Specifically, the sample was analyzed by LC/MS/MS compliant with 

QSM 5.3 Table B-15. The results of the decontamination water sample used during the SI are

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

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

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

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

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

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

member regarding the allowable materials within the sampling environment.

5.2 Soil Borings and Soil Sampling

Borings were installed in grass areas where applicable, to avoid disturbing concrete or asphalt 

surfaces. Soil samples were collected via direct-push technology (DPT), in accordance with the 

SI QAPP Addendum (AECOM, 2021a). A GeoProbe® 7822DT dual-tube sampling system was 

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

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

soil boring locations are shown on Figure 5-1, and depths are provided Table 5-1.
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AECOM 5-3

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

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

approximately 1 foot above the bedrock surface, and one subsurface soil sample at the mid-point 

between the surface and the bedrock interface. In borings where bedrock and/or refusal were

encountered at 6 feet bgs or shallower, only two soil samples were collected per boring; other

borings did not have enough recovery to sample three soil intervals. Consequently, two soil 

samples were collected at locations AOI1-1, AOI1-3, AOI2-2, AOI3-4, AOI3-5, and AOI3-6. At 

borings AOI1-2, AOI1-SS01, AOI1-SS02, AOI1-SS04, and AOI1-SS05, refusal was encountered 

at 2 feet bgs; therefore, only one sample was collected per boring location.

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

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

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

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

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

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

Soil borings completed during the SI at OCTC found soils dominated by fine-grained material with 

varying amounts of coarse-grained material, such as sand and gravel, overlying shallow basaltic 

bedrock. Depth to bedrock ranged from as shallow as approximately 2 feet bgs to beyond 21.5 

feet bgs. Borings were completed at depths between 2 and 21.5 feet bgs. These observations are 

consistent with the understood depositional environment of the region.

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

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

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

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

carbon (TOC) (USEPA Method 9060A) and pH (USEPA Method 9045D) in accordance with the

SI QAPP Addendum (AECOM, 2021a).

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

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

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

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

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

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

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

DPT borings were subsequently abandoned in accordance with the SI QAPP Addendum 

(AECOM, 2021a) using bentonite chips at completion of sampling activities. Borings were 

installed in unpaved areas to avoid disturbing concrete or asphalt surfaces.

5.3 Production Well Sampling

During the SI, six onsite production wells were sampled for groundwater. The locations of the 

wells are shown on Figure 5-1, and the screen intervals for the production wells are provided in 

Table 5-3.

Groundwater samples collected from production wells were sampled directly from the spigot. 

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

a PFAS-free marker or pen. 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) after each grab sample was 

collected. Additionally, a subsample of each groundwater sample was collected in a separate 
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Orchard Combat Training Center, Boise, Idaho

AECOM 5-4

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

noted in any of the groundwater samples. Samples were packaged on ice and transported via 

FedEx under standard CoC procedures to the laboratory and analyzed by LC/MS/MS compliant 

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

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

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

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

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

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

5.4 Sediment Sampling

Sediment samples were collected from AOI 3 at the Wastewater Lagoons and in accordance with 

the SI QAPP Addendum (AECOM, 2021a). Dedicated, PFAS-free sediment coring devices were 

used to collect the sediment samples from the first foot of sediment. The sediment was transferred 

to a Ziploc® bag, where the sample was homogenized, and stones in excess of 1 centimeter were 

removed. The sediment sample locations are shown on Figure 5-1, and sample depths are 

provided Table 5-1.

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

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

standard CoC procedures to the laboratory for analysis by LC/MS/MS compliant with QSM 5.3

Table B-15. Sediment samples were also analyzed for TOC (USEPA Method 9060A) and pH 

(USEPA Method 9045D), in accordance with the SI QAPP Addendum (AECOM, 2021a).

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

as the accompanying samples. MS/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, equipment reagent blank samples were collected at a rate of 5% and 

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

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

5.5 Synoptic Water Level Measurements

A synoptic groundwater gauging event was performed on 28 July 2021. Groundwater elevation 

measurements were collected from the six pre-existing production wells. Water level 

measurements were taken from the northern side of the well casings using a Global Water WL650 

Sonic Water Level Meter. A groundwater elevation map is provided in Figure 2-4. Groundwater 

elevation data are provided in Table 5-3. Although the inferred groundwater flow directions 

presented on Figure 2-4 are generally consistent with those reported in prior regional studies, 

there are several limitations to be considered. Due to the limited information about construction 

of the onsite production wells, a sonic water level indicator was used to collect water level 

measurements. Sonic water level indicators are less precise than probe water level indicators, 

and the accuracy of the readings depends on the acoustics of the well, which can be affected by 

anomalies like cracks in well casing, collars, borehole protrusions or irregularities, or other 

instruments down the well (e.g., pumps and piping). Additionally, given that these are active 

production wells utilized by the facility, it is unknown if water levels were collected during static 

conditions or during a drawdown recovery phase. 

5.6 Surveying

The well casings were surveyed by Idaho-licensed land surveyors on 12 November 2021,

following guidelines provided in the SOPs provided in the SI QAPP Addendum (AECOM, 2021a). 
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Orchard Combat Training Center, Boise, Idaho

AECOM 5-5

Survey data were collected from the casings where the depth to water measurements were 

recorded and were recorded in the applicable Universal Transverse Mercator zone projection with 

North American Datum 1983 (horizontal) and North American Vertical Datum 1988 (vertical). The 

surveyed well data are provided in Appendix B4.

5.7 Investigation-Derived Waste

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

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

Addendum (AECOM, 2021a) and with the DAGuidance for Addressing Releases of PFAS, Q18 (DA, 

2018).

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

Department of Transportation (DOT)-approved steel drums and left onsite on the south side of 

the Field Maintenance Shop (Appendix C). The approximate geographic coordinates of the 

drums are 43°17'51.96" N; 116°03'44.31" W. The soil IDW was not sampled and assumes the 

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

coordinate waste profiling, transportation, and disposal of the solid IDW under a separate 

contract.

Liquid IDW generated during SI activities (i.e., purge water and decontamination fluids) was 

contained in labeled, 55-gallon DOT-approved steel drum and left onsite on the north side of the 

Field Maintenance Shop (Appendix C). The liquid IDW was not sampled and assumed the PFAS 

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

Containerized liquid IDW will be managed and disposed of by ARNG (either by offsite disposal or 

onsite disposal with treatment, as appropriate) under a separate contract in accordance with SOP 

No. 042A (EA, 2021).

Geographic coordinates were collected using a global positioning system (GPS) where the soil 

IDW was placed. The IDW location is displayed on the figure in Appendix B5.

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

other environmental media generated during the field activities, were disposed of at a licensed 

solid waste landfill.

5.8 Laboratory Analytical Methods

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

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

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

5.9 Deviations from SI QAPP Addendum

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

documentation. The deviation is noted below and is documented in Field Change Request Forms 

(Appendix B3): 

• At AOI 1, five soil sample locations (two depth intervals; 0-2 feet bgs and 3-5 feet bgs) were 

added to the scope of the SI. The additional surface soil samples were located to the clearing 

south of the planned soil borings. Additional information was provided by the Fire Station 

personnel during fieldwork regarding the location of the fire training exercises in the area.

The surface soil locations were strategically placed based on topography, existing 

infrastructure, and logistics of the type of fire training that occurred. The locations were 

determined onsite and were the most probable area where the fire training exercises 
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Orchard Combat Training Center, Boise, Idaho

AECOM 5-6

occurred in 2014/2015. However, during the SI, early refusal was encountered at four of the 

five boring locations, and only one soil sample was collected from the four locations.

• Several soil borings did not have enough recovery to sample three soil intervals, as 

prescribed in the QAPP. Consequently, two soil samples were collected at locations AOI1-1, 

AOI1-3, AOI2-2, AOI3-4, AOI3-5, and AOI3-6. At boring AOI1-2, refusal was encountered 

at 2 feet bgs; therefore, only one sample was collected.

• QA/QC volume for pH/TOC analysis was inadvertently not collected for soil sample selected 

for those analytes.
Table 5-1

Site Inspection Samples by Medium

Site Inspection Report, Orchard Combat Training Center, Idaho

Sample Identification

Sample

Collection 

Date/Time

Sample Depth 

(feet bgs)

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

Comments

AOI1-1-SB-0-2 7/29/2021 15:46 0 - 2 x

AOI1-1-SB-0-2-DUP 7/29/2021 15:46 0 - 2 x FD

AOI1-1-SB-4-6 7/29/2021 15:55 4 - 6 x

AOI1-SS01-0-2 7/30/2021 10:30 0 - 2 x

AOI1-SS01-0-2-DUP 7/30/2021 10:30 0 - 2 x FD

AOI1-2-SB-0-2 7/29/2021 15:37 0 - 2 x

AOI1-SS02-0-2 7/30/2021 10:40 0 - 2 x

AOI1-SS02-0-2-MS-MSD 7/30/2021 10:40 0 - 2 x MS/MSD

AOI1-3-SB-0-2 7/30/2021 13:48 0 - 2 x

AOI1-3-SB-0-2-DUP 7/30/2021 13:48 0 - 2 x FD

AOI1-3-SB-0-2-MS 7/30/2021 13:48 0 - 2 x MS

AOI1-3-SB-0-2-MSD 7/30/2021 13:48 0 - 2 x MSD

AOI1-3-SB-5-7 7/30/2021 13:50 5 - 7 x x x

AOI1-SS03-0-2 7/30/2021 10:50 0 - 2 x

AOI1-SS03-3-5 7/30/2021 10:45 3 - 5 x

AOI1-SS04-0-2 7/30/2021 10:56 0 - 2 x

AOI1-SS05-0-2 7/30/2021 11:03 0 - 2 x

AOI1-SS05-0-2-DUP 7/30/2021 11:03 0 - 2 x FD

AOI2-1-0-2 7/29/2021 9:30 0 - 2 x x x

AOI2-1-13-15 7/29/2021 10:00 13 - 15 x

AOI2-1-20-21.5 7/29/2021 10:10 20 - 21.5 x

AOI2-2-0-2 7/29/2021 8:52 0 - 2 x

AOI2-2-5-6 7/29/2021 9:00 5 - 6 x

AOI2-3-0-2 7/29/2021 11:05 0 - 2 x

AOI2-3-0-2-MS 7/29/2021 11:05 0 - 2 x MS

AOI2-3-0-2-MSD 7/29/2021 11:05 0 - 2 x MSD

AOI2-3-13-15 7/29/2021 11:30 13 - 15 x

AOI2-3-20-21.5 7/29/2021 11:40 20 - 21.5 x

AOI3-3-SB-0-2 7/29/2021 17:01 0 - 2 x x x

AOI3-3-SB-6-8 7/29/2021 17:15 6 - 8 x

AOI3-3-SB-9-11 7/29/2021 15:13 9 - 11 x

AOI3-4-SB-0-2 7/30/2021 9:15 0 - 2 x

AOI3-4-SB-5-7 7/30/2021 9:30 5 - 7 x

AOI3-5-SB-0-2 7/30/2021 8:00 0 - 2 x

AOI3-5-SB-0-2-DUP 7/30/2021 8:00 0 - 2 x FD

AOI3-5-SB-5.5-6 7/30/2021 8:10 5.5 - 6 x

AOI3-6-SB-0-2 7/29/2021 17:58 0 - 2 x

AOI3-6-SB-7.5-9 7/29/2021 18:10 7.5 - 9 x

SRTF-1-072821 7/28/2021 13:50 NA x

SRTF-1-072821-DUP 7/28/2021 13:50 NA x FD

SRTF-1-072821-MS 7/28/2021 13:50 NA x MS

SRTF-1-072821-MSD 7/28/2021 13:50 NA x MSD

BRUMPTON-1-072821 7/28/2021 15:50 NA x

Soil Samples

Production Well Samples

AECOM 5-7
Table 5-1

Site Inspection Samples by Medium

Site Inspection Report, Orchard Combat Training Center, Idaho

Sample Identification

Sample

Collection 

Date/Time

Sample Depth 

(feet bgs)

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

Comments

ORTC-1-072821 7/28/2021 11:00 NA x

MATES-1-072821 7/28/2021 7:25 NA x

MPRCH-1-072821 7/28/2021 14:57 NA x

ASP-1-072821 7/28/2021 12:50 NA x

AOI3-1-SD-01 7/30/2021 13:10 0 - 1 x

AOI3-1-SD-01-DUP 7/30/2021 13:10 0 - 1 x FD

AOI3-1-SD-01-MS 7/30/2021 13:10 0 - 1 x MS

AOI3-1-SD-01-MSD 7/30/2021 13:10 0 - 1 x MSD

AOI3-1-SD-02 7/30/2021 13:00 0 - 1 x

OCTC-DECON-01 7/27/2021 14:12 NA x

FRB-01-073021 7/30/2021 7:55 NA x

OCTC-ERB-01 7/29/2021 10:58 NA x DPT shoe

OCTC-ERB-02 7/29/2021 11:45 NA x DPT shoe

OCTC-ERB-03-073021 7/30/2021 11:05 NA x sediment sampler

Notes:

AOI = Area of Interest

ASTM = American Society for Testing and Materials

bgs = below ground surface

DPT = direct push technology

ERB = equipment rinsate blank

FD = field duplicate

FRB = field reagent blank

LC/MS/MS = Liquid Chromatography Mass Spectrometry

MS/MSD = matrix spike/ matrix spike duplicate

QSM = Quality Systems Manual

SB = soil boring

SD = sediment

TOC = total organic carbon

USEPA = United States Environmental Protection Agency

Quality Control Samples

Sediment Samples

AECOM 5-8
Table 5-2

Soil Boring Depths

Site Inspection Report, Orchard Combat Training Center, Idaho

Area of 

Interest

Boring 

Location

Soil Boring 

Depth 

(feet bgs)

AOI1-1 7AOI1-2 2AOI1-3 7AOI2-1 21.5AOI2-2 5.5AOI2-3 21.5AOI3-3 11AOI3-4 7.7AOI3-5 8.5AOI3-6 9

Notes:bgs = below ground surface

123

AECOM 
Table 5-3

Production Well Screen Intervals and Groundwater Elevations

Site Inspection Report, Orchard Combat Training Center, Idaho

Well ID Well Depth (feet bgs)

Well Screen 

Interval 

(feet bgs)

Top of Casing 

Elevation 

(feet NAVD88)

Ground Surface 

Elevation 

(feet NAVD88)

Depth to 

Water

(feet btoc)

Depth to 

Water

(feet bgs

ORTC-1 755 735 - 755 3148.498 3147.182 550.8 549.5 

MATES-1 680 Unknown1 3139.562 3138.369 468 467 

SRTF-1 8202 720 - 820 3244.017 3243.704 637.4 637.1 

ASP-1 780 660 - 680 760 - 780 3167.918 3166.872 522.3 521.3 

BRUMPTON-1 557 487 - 557 3061.725 3060.413 424.5 423.2 

MPRCH-1 963 851 - 9633 3292.601 3291.349 776 775 

Notes:

1. Unknown screen interval. Casing is to 680 feet bgs and total boring depth is to 753 feet bgs.2. Well depth assumed to be as deep as well screen.3. Well is an open hole.bgs = below ground surfacebtoc = below top of casingNA = not applicableNAVD88 = North American Vertical Datum 1988

AECOM 
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AOI 2

AOI 3

AOI3-1 AOI3-2

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AOI3-4

AOI3-5

AOI3-6

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&<

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Co rder Creek

AOI 1

AOI 1 MPRCH-1

SRTF-1 ASP-1

BRUMPTON-1

AOI1-2

AOI1-3

AOI1-SS01

AOI1-SS02

Figure 5-1

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Ochard Combat Training Center, ID

8/17/2022

8/17/2022

8/17/2022

MS

CH

CM

GIS BY

CHK BY

PM

Base Map: The USDA-FSA Aerial Photography Field office asks to be credited in

derived products.

8/17/2022

Site Inspection Sample Locations

12420 Milestone Center Drive

Germantown, MD 20876

&<

Production Well Sample

?! Soil Boring

"J Sediment Sample

"S Surface Soil Sample

Area of Interest

Facility Boundary

Water Body

Wetland

River/Stream

Canal/Ditch

Combine Sanitary and Stormwater Sewer

MATES

1:9,240 ­

0 0.75 1.5 3

Miles

0 385 770 1,540

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1 2

1

2

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"S

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AOI1-2

AOI1-1

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AOI1-SS01

AOI1-SS03 AOI1-SS02

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AOI 1

AOI 1

PROJECT

AECOM 5-11
Site Inspection Report

Orchard Combat Training Center, Boise, Idaho

THIS PAGE INTENTIONALLY BLANK

AECOM 5-12
Site Inspection Report

Orchard Combat Training Center, Boise, Idaho

AECOM 6-1

6. Site Inspection Results 

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

presented in Section 6.1. A discussion of the results is provided in Section 6.3 through Section 

6.6. Table 6-2 through Table 6-6 present results in soil, sediment, or groundwater for the relevant 

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

are provided in Appendix G. 

6.1 Screening Levels 

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

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

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

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

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

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

6-1 below.

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

Analyteb

Residential

(Soil)

(μg/kg)a 

0-2 feet bgs

Industrial/ 

Commercial 

Composite 

Worker

(Soil)

(μg/kg)a 

2-15 feet bgs

Tap Water

(Groundwater)

(ng/L)a

PFOA 19 250 6 

PFOS 13 160 4

PFBS 1,900 25,000 601 

PFHxS 130 1,600 39

PFNA 19 250 6 

Notes:

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

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

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

present. 

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

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

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

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

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

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

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

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

and the industrial/commercial worker scenario is applied to shallow subsurface soil results (2 to 

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

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

Orchard Combat Training Center, Boise, Idaho

AECOM 6-2

6.2 Soil Physicochemical Analyses

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

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

of the TOC and pH sampling. 

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

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

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

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

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

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

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

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

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

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

6.3 AOI 1

This section presents the analytical results for soil in comparison to SLs for AOI 1: Range 2 FTA.

The soil results are summarized on Table 6-2 through Table 6-4. Soil results are presented on 

Figure 6-1 through Figure 6-15.

6.3.1 AOI 1 Soil Analytical Results

Figure 6-1 through Figure 6-15 present the ranges of detections in soil. Table 6-2 through Table 

6-4 summarize the soil results and Table 6-6 summarizes the sediment results.

Soil was sampled from surface soil (0 to 2 feet bgs) from boring locations AOI1-1 through AOI1-3 

and AOI1-SS01 through AOI1-SS05. Soil was also sampled from shallow subsurface soil 

(between 3 to 7 feet bgs) from AOI1-1, AOI1-3, and AOI1-SS03. Deep subsurface soil was not 

collected from AOI 1 during the SI.

PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in surface soil at concentrations below 

their respective SLs. PFOA was detected in two of eight locations, with concentrations of 0.255 J 

micrograms per kilogram (μg/kg) and 0.166 J μg/kg. PFOS was detected in five of the eight 

locations, with concentrations ranging from 0.079 J μg/kg to 0.452 J μg/kg. PFHxS was detected 

in three of the eight locations, with concentrations ranging from 0.043 J μg/kg to 4.82 μg/kg. PFNA

was detected in three of the eight locations, with concentrations ranging from 0.025 J μg/kg to 

0.040 J μg/kg. PFBS was detected in two of eight locations, with concentrations of 1.65 μg/kg at 

AOI1-SS04 and 0.037 J μg/kg at AOI1-SS05.

In shallow subsurface soil, PFHxS was detected in one sample below the SL, with a concentration 

of 0.049 J μg/kg. PFOA, PFOS, PFNA, and PFBS were not detected.

6.3.2 AOI 1 Conclusions

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

below their SLs. Therefore, further evaluation at AOI 1 is not warranted. No groundwater samples 

were collected from AOI 1 during the SI.
Site Inspection Report

Orchard Combat Training Center, Boise, Idaho

AECOM 6-3

6.4 AOI 2

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

AOI 2: OCTC Fire Station. The results in soil are summarized on Table 6-2 through Table 6-4. 

Soil results are presented on Figure 6-1 through Figure 6-15.

6.4.1 AOI 2 Soil Analytical Results

Figure 6-1 through Figure 6-15 present the ranges of detections in soil. Table 6-2 through Table 

6-4 summarize the soil results.

Soil was sampled from surface soil (0 to 2 feet bgs) from boring locations AOI2-1 through AOI2-3, 

shallow subsurface soil (between 5 to 15 feet bgs) from boring locations AOI2-1 through AOI2-3,

and deep subsurface soil (20 to 21.5 feet bgs) from boring locations AOI2-1 and AOI2-3. 

PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in surface soil, at concentrations below 

their SLs. PFOA was detected at AOI02-01, with a concentration of 1.63 μg/kg. PFOS was 

detected at locations AOI2-01 and AOI2-03, with concentrations of 2.79 μg/kg and 0.062 J μg/kg, 

respectively. PFHxS was detected at AOI02-01, with a concentration of 0.439 J μg/kg. PFNA was 

detected at AOI02-01, with a concentration of 0.501 J μg/kg. PFBS was detected at AOI02-01, 

with a concentration of 0.070 J μg/kg. PFOA, PFOS, PFHxS, PFNA, and PFBS were not detected 

in shallow and deep subsurface soil. 

6.4.2 AOI 2 Conclusions

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

concentrations below their respective SLs. Therefore, further evaluation at AOI 2 is not warranted.

No groundwater samples were collected from AOI 2 during the SI.

6.5 AOI 3

This section presents the analytical results for soil and sediment in comparison to SLs for AOI 3: 

Wastewater Lagoons. The results in soil and sediment are summarized on Table 6-2 through 

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

6-15 and Figure 6-21 through Figure 6-22.

6.5.1 AOI 3 Soil Analytical Results

Figure 6-1 through Figure 6-15 present the ranges of detections in soil. Table 6-2 through Table 

6-4 summarize the soil results.

Soil was sampled from surface soil (0 to 2 feet bgs) from boring locations AOI3-3 through AOI3-

6. Soil was also sampled from shallow subsurface soil (between 5 to 11 feet bgs) from boring 

locations AOI3-4, AOI3-5, and AOI3-6. Deep subsurface soil was not collected during the SI.

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

SLs. PFOA was detected at AOI3-6, with a concentration of 0.109 J μg/kg. PFOS was detected 

at AOI3-6, with a concentration of 0.330 J μg/kg. PFHxS was detected at locations AOI3-4 and 

AOI3-6, with concentrations of 0.043 J μg/kg and 0.056 J μg/kg, respectively. PFBS was detected 

at locations AOI3-5 and AOI3-6, with concentrations of 0.045 J μg/kg and 0.023 J μg/kg, 

respectively. PFNA was not detected in surface soil.

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

SLs. PFOS was detected at AOI3-3, with a concentration of 0.283 J μg/kg. PFHxS was detected 
Site Inspection Report

Orchard Combat Training Center, Boise, Idaho

AECOM 6-4

at three of the five locations, with concentrations ranging from 0.117 J μg/kg to 0.204 J μg/kg. 

PFBS was detected at AOI3-5, with a concentration of 0.067 J μg/kg. PFOA and PFNA were not 

detected in shallow subsurface soil.

6.5.2 AOI 3 Sediment Analytical Results

Figure 6-21 and Figure 6-22 present the ranges of detections in sediment. Table 6-6 summarizes 

the sediment results.

Sediment was sampled from two locations, AOI3-1-SD-01 and AOI3-1-SD-02. PFOA, PFOS, 

PFHxS, PFNA, and PFBS were detected at AOI3-1-SD-01, with concentrations ranging from

0.478 J μg/kg to 30.2 J μg/kg. All five compounds were non-detect at AOI3-1-SD-02.

6.5.3 AOI 3 Conclusions

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

concentrations below their SLs. Therefore, further evaluation at AOI 3 is not warranted. There are 

no established SLs for sediment; therefore, these results are presented for informational purposes 

only. No groundwater samples were collected from AOI 3 during the SI.

6.6 Production Wells

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

production wells across the facility. The results from the July 2021 SI sampling event in 

groundwater are summarized on Table 6-5 and are presented on Figure 6-16 through Figure 6-

20. IDARNG performed prior sampling of the production wells in September 2018 and August 

2020. During these events, the production well samples were analyzed via EPA method 537. 

PFAS were not detected above the method detection limits in each sample during both prior 

events. The lab reports for these sampling events are in Appendix G.

6.6.1 Groundwater Analytical Results

PFOS was the only compound detected during production well sampling. PFOA, PFHxS, PFNA, 

and PFBS were not detected in any of the six production wells. When only one PFAS is present, 

a health quotient of 1.0 can be used to calculate the SL for that single compound. Therefore, the 

applicable SL for PFOS in 40 nanograms per liter (ng/L). PFOS was detected in groundwater, at 

a concentration below its SL of 40 ng/L at the Snake River Training Facility (SRTF) well, with a

concentration of 4.49 ng/L. PFOS was also detected in groundwater at concentration below its SL

at the BRUMPTON well, with a concentration of 1.81 J ng/L. PFOS was not detected at the 

remaining four production wells. 

6.6.2 Production Wells Conclusions

Based on the results of the SI, PFOS was the only compound detected in groundwater, at a 

concentration below its SL of 40 ng/L. PFOA, PFHxS, PFNA, and PFBS were not detected in any 

of the six production wells. Therefore, no further evaluation of the production wells, SRTF or 

BRUMPTON, is warranted. 
Table 6-2

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

Site Inspection Report, Orchard Combat Training Center

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Resu

PFBS 1900 ND U ND U ND U ND U ND U ND U ND U ND U ND PFHxS 130 ND U ND U ND U ND U ND U ND U ND U 0.043 J ND PFNA 19 ND U ND U ND U ND U ND U 0.040 J ND UJ 0.037 J ND PFOA 19 ND U ND U ND U ND U ND U ND U ND U ND U ND PFOS 13 ND U ND U 0.085 J ND U ND U 0.452 J 0.079 J 0.238 J ND 

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acidPFOA perfluorooctanoic acidPFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AOI Area of InterestU = The analyte was not detected at a level greater than or equal to the adjusted DL DUP duplicate

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

ft feet

Notes HQ hazard quotient

ND = Analyte not detected above the LOD. LOD values are presented in Appendix F. ID identification

LCMSMS liquid chromatography with tandem mLOD limit of detectionND analyte not detected above the LOD. OSD Office of the Secretary of DefenseQSM Quality Systems ManualQual interpreted qualifierSB soil boringSS surface soilUSEPA United States Environmental Protectioμg/kg micrograms per kilogram

a. Assistant Secretary of Defense, July 2022. Risk Based Screening Levels Calculated for PFOA, PFOS, PFBS, PFHxS, and PFNA in Groundwater or Soil using USEPA’s Regional Screening Level Calculator. HQ=0.1, May 2022. Soil screening levels based on residential scenario for incendental ingestion of contaminated soil.

AOI01

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

AOI1-SS02-0-2

07/30/2021

0-2 ft

AO

0

AOI1-SS01-0-2

07/30/2021

0-2 ft

AOI1-SS01-0-2-DUP

07/30/2021

0-2 ft

AOI1-3-SB-0-2

07/30/2021

0-2 ft

AOI1-3-SB-0-2-DUP

07/30/2021

0-2 ft

AOI1-1-SB-0-2-DUP

07/29/2021

0-2 ft

AOI1-2-SB-0-2

07/29/2021

0-2 ft

Area of Interest

Sample ID

Sample Date

Depth

AOI1-1-SB-0-2

07/29/2021

0-2 ft

AECOM 
Table 6-2

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

Site Inspection Report, Orchard Combat Training Center

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Resu

PFBS 1900 0.037 J ND UJ 0.070 J ND U ND U ND U ND U 0.045 J ND PFHxS 130 0.345 J 0.111 J 0.439 J ND U ND U ND U 0.043 J ND U ND PFNA 19 0.025 J ND UJ 0.501 J ND U ND U ND U ND U ND U ND PFOA 19 0.166 J ND UJ 1.63 ND U ND U ND U ND U ND U ND PFOS 13 0.237 J 0.079 J 2.79 ND U 0.062 J ND U ND U ND U ND 

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acidPFOA perfluorooctanoic acidPFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AOI Area of InterestU = The analyte was not detected at a level greater than or equal to the adjusted DL DUP duplicate

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

ft feet

Notes HQ hazard quotient

ND = Analyte not detected above the LOD. LOD values are presented in Appendix F. ID identification

LCMSMS liquid chromatography with tandem mLOD limit of detectionND analyte not detected above the LOD. OSD Office of the Secretary of DefenseQSM Quality Systems ManualQual interpreted qualifierSB soil boringSS surface soilUSEPA United States Environmental Protectioμg/kg micrograms per kilogram

a. Assistant Secretary of Defense, July 2022. Risk Based Screening Levels Calculated for PFOA, PFOS, PFBS, PFHxS, and PFNA in Groundwater or Soil using USEPA’s Regional Screening Level Calculator. HQ=0.1, May 2022. Soil screening levels based on residential scenario for incidental ingestion of contaminated soil.

AOI01 AOI02 AOI03

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

AOI3-5-SB-0-2

07/30/2021

0-2 ft

AOI3-

0

AOI3-3-SB-0-2

07/29/2021

0-2 ft

AOI3-4-SB-0-2

07/30/2021

0-2 ft

AOI2-2-0-2

07/29/2021

0-2 ft

AOI2-3-0-2

07/29/2021

0-2 ft

AOI1-SS05-0-2-DUP

07/30/2021

0-2 ft

AOI2-1-0-2

07/29/2021

0-2 ft

Area of Interest

Sample ID

Sample Date

Depth

AOI1-SS05-0-2

07/30/2021

0-2 ft

AECOM 
Table 6-3

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

Site Inspection Report, Orchard Combat Training Center

Analyte OSD Screening 

Level a

Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Result Qual Resu

PFBS 25000 ND U ND U ND U ND U ND U ND U ND U ND U ND PFHxS 1600 ND U ND U 0.049 J ND U ND U ND U ND U 0.117 J ND PFNA 250 ND U ND U ND U ND U ND U ND U ND U ND U ND PFOA 250 ND U ND U ND U ND U ND U ND U ND U ND U ND PFOS 160 ND U ND U ND U ND U ND U ND U ND U 0.283 J ND 

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acidPFOA perfluorooctanoic acidPFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AOI Area of InterestU = The analyte was not detected at a level greater than or equal to the adjusted DL DL detection limit

ft feet

Notes HQ hazard quotient

ND = Analyte not detected above the LOD. LOD values are presented in Appendix F. ID identification

LCMSMS liquid chromatography with tandem mLOD limit of detectionND analyte not detected above the LOD. OSD Office of the Secretary of DefenseQSM Quality Systems ManualQual interpreted qualifierSB soil boringUSEPA United States Environmental Protectioμg/kg micrograms per kilogram

Area of Interest

Sample ID

Sample Date

Depth

AOI1-1-SB-4-6

07/29/2021

4-6 ft

AOI1-3-SB-5-7

07/30/2021

5-7 ft

AOI1-SS03-3-5

07/30/2021

3-5 ft 13-15 ft

AOI3-3-SB-6-8

07/29/2021

6-8 ft

AOI2-1-13-15

07/29/2021

13-15 ft

AOI2-2-5-6

07/29/2021

5-6 ft

a. Assistant Secretary of Defense, July 2022. Risk Based Screening Levels Calculated for PFOA, PFOS, PFBS, PFHxS, and PFNA in Groundwater or Soil using USEPA’s Regional Screening Level Calculator. HQ=0.1, May 2022. Soil screening levels based on industrial/commercial composite worker scenario for incidental ingestion of contaminated soil.

AOI01 AOI02 AOI03

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

AOI3-3-SB-9-11

07/29/2021

9-11 ft

AO

0

AOI2-3-13-15

07/29/2021

AECOM 
Table 6-3

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

Site Inspection Report, Orchard Combat Training Center

Analyte OSD Screening 

Level a

Result Qual

PFBS 25000 ND UPFHxS 1600 0.204 JPFNA 250 ND UPFOA 250 ND UPFOS 160 ND U

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobutanesulfonic acid

References PFHxS perfluorohexanesulfonic acid

PFNA perfluorononanoic acidPFOA perfluorooctanoic acidPFOS perfluorooctanesulfonic acid

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration AOI Area of InterestU = The analyte was not detected at a level greater than or equal to the adjusted DL DL detection limit

ft feet

Notes HQ hazard quotient

ND = Analyte not detected above the LOD. LOD values are presented in Appendix F. ID identification

LCMSMS liquid chromatography with tandem mLOD limit of detectionND analyte not detected above the LOD. OSD Office of the Secretary of DefenseQSM Quality Systems ManualQual interpreted qualifierSB soil boringUSEPA United States Environmental Protectioμg/kg micrograms per kilogram

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

a. Assistant Secretary of Defense, July 2022. Risk Based Screening Levels Calculated for PFOA, PFOS, PFBS, PFHxS, and PFNA in Groundwater or Soil using USEPA’s Regional Screening Level Calculator. HQ=0.1, May 2022. Soil screening levels based on industrial/commercial composite worker scenario for incidental ingestion of contaminated soil.

Area of Interest

Sample ID

Sample Date

Depth

AOI03

AOI3-6-SB-7.5-9

07/29/2021

7.5-9 ft

AECOM 
Table 6-4

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

Site Inspection Report, Orchard Combat Training Center

Area of Interest

Sample ID

Sample Date

Depth

Analyte Result Qual Result Qual

PFBS ND U ND UPFHxS ND U ND UPFNA ND U ND UPFOA ND U ND UPFOS ND U ND U

Interpreted Qualifiers Chemical AbbreviationsU = The analyte was not detected at a level greater than or equal to the adjusted DL PFBS perfluorobutanesulfonic acid

PFHxS perfluorohexanesulfonic acid

Notes PFNA perfluorononanoic acid

ND = Analyte not detected above the LOD. LOD values are presented in Appendix F. PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acidAcronyms and Abbreviations

AOI Area of InterestDL detection limitft feetID identificationLCMSMS liquid chromatography with tandem mass LOD limit of detectionND analyte not detected above the LOD. LOD QSM Quality Systems ManualQual interpreted qualifierSB soil boringμg/kg micrograms per kilogram

AOI02

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

AOI2-1-20-21.5

07/29/2021

20-21.5 ft

AOI2-3-20-21.5

07/29/2021

20-21.5 ft

AECOM 
Table 6-5

PFOA, PFOS, PFBS, PFNA, and PFHxS Results in Onsite Production Wells

Site Inspection Report, Orchard Combat Training Center

Analyte OSD Screening 

Level a

OSD Screening 

Level b

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

PFBS 601 6,010 ND U ND U ND U ND U ND U ND U ND UPFHxS 39 394 ND U ND U ND U ND U ND U ND U ND U

PFNA 6 59 ND U ND U ND U ND U ND U ND U ND U

PFOA 6 60 ND U ND U ND U ND U ND U ND U ND U

PFOS 4 40 ND U 1.81 J ND U ND U ND U 2.91 J 4.49

Grey Fill Detected concentration exceeded OSD Screening Levels Chemical Abbreviations

PFBS perfluorobu

References PFHxS perfluorohe

PFNA perfluoronoPFOA perfluoroocPFOS perfluorooc

Interpreted Qualifiers Acronyms and Abbreviations

J = Estimated concentration DUP duplicateU = The analyte was not detected at a level greater than or equal to the adjusted DL DL detection li

HQ hazard quo

Notes ID identificatioND = Analyte not detected above the LOD. LOD values are presented in Appendix F. LCMSMS liquid chrom

LOD limit of deteND analyte not OSD Office of thQSM Quality SysQual interpreted USEPA United Statng/l nanogram 

07/28/2021

MATES-1-072821

Sample Date 07/28/2021

ASP-1-072821

07/28/2021

Water, LCMSMS compliant with QSM 5.3 Table B-15 (ng/l)

a. Assistant Secretary of Defense, July 2022. Risk Based Screening Levels Calculated for PFOA, PFOS, PFBS, PFHxS, and PFNA in Groundwater or Soil using USEPA’s Regional Screening Level Calculator. HQ=0.1, May 2022 Groundwater screening levels based on residential scenario for direct ingestion of groundwater. b. 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=1.0, May 2022. Groundwater screening levels based on residential scenario for direct ingestion of groundwater. HQ=1.0 when a single PFAS is present.

Area of Interest

Sample ID

Sitewide

SRTF-1-072821

07/28/2021

SRTF-1-072821-DUP

07/28/2021

MPRCH-1-072821

07/28/2021

ORTC-1-072821

07/28/2021

BRUMPTON-1-072821

AECOM 
Table 6-6

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

Site Inspection Report, Orchard Combat Training Center

Area of Interest

Sample ID

Sample Date

Depth

Analyte Result Qual Result Qual Result Qual

PFBS 1.35 J 0.674 J ND UPFHxS 2.70 J 1.38 J ND UPFNA 1.03 J 0.478 J ND UPFOA 3.06 J- 1.42 J- ND UPFOS 30.2 J 15.9 ND U

Interpreted Qualifiers Chemical AbbreviationsJ = Estimated concentration PFBS perfluorobutanesulfonic acidJ- = Estimated concentration, biased low PFHxS perfluorohexanesulfonic acid

U = The analyte was not detected at a level greater than or equal to the adjusted DL PFNA perfluorononanoic acid

PFOA perfluorooctanoic acid

Notes PFOS perfluorooctanesulfonic acidND = Analyte not detected above the LOD. LOD values are presented in Appendix F.

Acronyms and Abbreviations

AOI Area of InterestDUP duplicateDL detection limitft feetID identificationLCMSMS liquid chromatography with tandem mass LOD limit of detectionND analyte not detected above the LOD. LOD QSM Quality Systems ManualQual interpreted qualifierSD sedimentμg/kg micrograms per kilogram

AOI03

AOI3-1-SD-02

07/30/2021

0-1 ft

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

AOI3-1-SD-01

07/30/2021

0-1 ft

AOI3-1-SD-01-DUP

07/30/2021

0-1 ft

AECOM 
Site Inspection Report

Orchard Combat Training Center, Boise, Idaho

THIS PAGE INTENTIONALLY BLANK

AECOM 
AOI1-2

AOI1-1

AOI1-3

AOI1-SS01

AOI1-SS03 AOI1-SS02

AOI1-SS04

AOI1-SS05

Figure 6-1

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Ochard Combat Training Center, ID

8/17/2022

8/17/2022

8/17/2022

MS

CH

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO,

USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri

8/17/2022

PFOA Detections in Soil, AOI 1

12420 Milestone Center Drive

Germantown, MD 20876

Legend

Facility Boundary

1:2,400

0 100 200 400

Feet ­

AOI1-1

AOI1-3

AOI1-SS03

Shallow Intermediate

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

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

PROJECT

PFOA Results (μg/Kg)

ND

>ND - 19

>19 - 250

>250 - 2,500

>2,500

AECOM 6-13
AOI2-1

AOI2-3

AOI2-2

Figure 6-2

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Ochard Combat Training Center, ID

8/17/2022

8/17/2022

8/17/2022

MS

CH

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO,

USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri

8/17/2022

PFOA Detections in Soil, AOI 2

12420 Milestone Center Drive

Germantown, MD 20876

Legend

Facility Boundary

1:1,200

Combine Sanitary and Stormwater Sewer ­

AOI2-1

AOI2-3

AOI2-2

AOI2-1

AOI2-3

Shallow Intermediate Deep

0 50 100 200

Feet

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

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

PROJECT

PFOA Results (μg/Kg)

ND

>ND - 19

>19 - 250

>250 - 2,500

>2,500

AECOM 6-14
AOI3-3

AOI3-4

AOI3-5

AOI3-6

Figure 6-3

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Ochard Combat Training Center, ID

8/17/2022

8/17/2022

8/17/2022

MS

CH

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO,

USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri

8/17/2022

PFOA Detections in Soil, AOI 3

12420 Milestone Center Drive

Germantown, MD 20876

Legend

Facility Boundary

1:2,400

0

Combine Sanitary and Stormwater Sewer

100 200 400

Feet ­

AOI3-3

AOI3-4

AOI3-5

AOI3-6

AOI3-3

Shallow Intermediate Deep

PROJECT

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

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

PFOA Results (μg/Kg)

ND

>ND - 19

>19 - 250

>250 - 2,500

>2,500

AECOM 6-15
AOI1-2

AOI1-1

AOI1-3

AOI1-SS01

AOI1-SS03 AOI1-SS02

AOI1-SS04

AOI1-SS05

Figure 6-4

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Ochard Combat Training Center, ID

8/17/2022

8/17/2022

8/17/2022

MS

CH

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO,

USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri

8/17/2022

C\U\tkih\ODiAECOM Dit\ARNGPFASGIS60552172\MXD\ID\OCTCFi\OCTCSIFi\SIRt\Rlt\Fi64OCTCSISilRltPFOSAOI1d

PFOS Detections in Soil, AOI 1

12420 Milestone Center Drive

Germantown, MD 20876

Legend

Facility Boundary

1:2,400 ­

AOI1-1

AOI1-3

AOI1-SS03

Shallow Intermediate

0 100 200 400

Feet

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

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

PROJECT

PFOS Results (μg/Kg)

ND

>ND - 13

>13 - 160

>160 - 1,600

>1,600

AECOM 6-16
AOI2-1

AOI2-3

AOI2-2

Figure 6-5

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Ochard Combat Training Center, ID

8/17/2022

8/17/2022

8/17/2022

MS

CH

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO,

USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri

8/17/2022

PFOS Detections in Soil, AOI 2

12420 Milestone Center Drive

Germantown, MD 20876

Legend

Facility Boundary

Combine Sanitary and Stormwater Sewer

1:1,200 ­

AOI2-1

AOI2-3

AOI2-2

AOI2-1

AOI2-3

Shallow Intermediate Deep

0 50 100 200

Feet

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

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

PROJECT

PFOS Results (μg/Kg)

ND

>ND - 13

>13 - 160

>160 - 1,600

>1,600

AECOM 6-17
AOI3-3

AOI3-4

AOI3-5

AOI3-6

Figure 6-6

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Ochard Combat Training Center, ID

8/17/2022

8/17/2022

8/17/2022

MS

CH

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO,

USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri

8/17/2022

PFOS Detections in Soil, AOI 3

12420 Milestone Center Drive

Germantown, MD 20876

Legend

Facility Boundary

Combine Sanitary and Stormwater Sewer

1:2,400 ­

AOI3-3

AOI3-4

AOI3-5

AOI3-6

AOI3-3

Shallow Intermediate Deep

0 100 200 400

Feet

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

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

PROJECT

PFOS Results (μg/Kg)

ND

>ND - 13

>13 - 160

>160 - 1,600

>1,600

AECOM 6-18
AOI1-2

AOI1-1

AOI1-3

AOI1-SS01

AOI1-SS03 AOI1-SS02

AOI1-SS04

AOI1-SS05

Figure 6-7

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Ochard Combat Training Center, ID

8/17/2022

8/17/2022

8/17/2022

MS

CH

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO,

USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri

8/17/2022

PFBS Detections in Soil, AOI 1

12420 Milestone Center Drive

Germantown, MD 20876

Legend

Facility Boundary

1:2,400 ­

AOI1-1

AOI1-3

AOI1-SS03

Shallow Intermediate

0 100 200 400

Feet

PROJECT

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

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

PFBS Results (μg/Kg)

ND

>ND - 10

>10 - 1,900

>1,900 - 25,000

>25,000

AECOM 6-19
AOI2-1

AOI2-3

AOI2-2

Figure 6-8

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Ochard Combat Training Center, ID

8/17/2022

8/17/2022

8/17/2022

MS

CH

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO,

USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri

8/17/2022

PFBS Detections in Soil, AOI 2

12420 Milestone Center Drive

Germantown, MD 20876

Legend

Facility Boundary

Combine Sanitary and Stormwater Sewer

1:1,200 ­

AOI2-1

AOI2-3

AOI2-2

AOI2-1

AOI2-3

Shallow Intermediate Deep

0 50 100 200

Feet

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

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

PROJECT

PFBS Results (μg/Kg)

ND

>ND - 10

>10 - 1,900

>1,900 - 25,000

>25,000

AECOM 6-20
AOI3-3

AOI3-4

AOI3-5

AOI3-6

Figure 6-9

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Ochard Combat Training Center, ID

8/17/2022

8/17/2022

8/17/2022

MS

CH

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO,

USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri

8/17/2022

PFBS Detections in Soil, AOI 3

12420 Milestone Center Drive

Germantown, MD 20876

Legend

Facility Boundary

Combine Sanitary and Stormwater Sewer

1:2,397 ­

AOI3-3

AOI3-4

AOI3-5

AOI3-6

AOI3-3

Shallow Intermediate Deep

0 100 200 400

Feet

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

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

PROJECT

PFBS Results (μg/Kg)

ND

>ND - 10

>10 - 1,900

>1,900 - 25,000

>25,000

AECOM 6-21
AOI1-2

AOI1-1

AOI1-3

AOI1-SS01

AOI1-SS03 AOI1-SS02

AOI1-SS04

AOI1-SS05

Figure 6-10

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Ochard Combat Training Center, ID

8/17/2022

8/17/2022

8/17/2022

MS

CH

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO,

USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri

8/17/2022

PFHxS Detections in Soil, AOI 1

12420 Milestone Center Drive

Germantown, MD 20876

Legend

Facility Boundary

1:2,400 ­

AOI1-1

AOI1-3

AOI1-SS03

Shallow Intermediate

0 100 200 400

Feet

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

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

PROJECT

PFHxS Results (μg/Kg)

ND

>ND - 10

>10 - 130

>130 - 1,600

>1,600

AECOM 6-22
AOI2-1

AOI2-3

AOI2-2

Figure 6-11

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Ochard Combat Training Center, ID

8/17/2022

8/17/2022

8/17/2022

MS

CH

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO,

USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri

8/17/2022

PFHxS Detections in Soil, AOI 2

12420 Milestone Center Drive

Germantown, MD 20876

Legend

Facility Boundary

Combine Sanitary and Stormwater Sewer

1:1,200 ­

AOI2-1

AOI2-3

AOI2-2

AOI2-1

AOI2-3

Shallow Intermediate Deep

0 50 100 200

Feet

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

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

PROJECT

PFHxS Results (μg/Kg)

ND

>ND - 10

>10 - 130

>130 - 1,600

>1,600

AECOM 6-23
AOI3-3

AOI3-4

AOI3-5

AOI3-6

Figure 6-12

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Ochard Combat Training Center, ID

8/17/2022

8/17/2022

8/17/2022

MS

CH

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO,

USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri

8/17/2022

PFHxS Detections in Soil, AOI 3

12420 Milestone Center Drive

Germantown, MD 20876

Legend

Facility Boundary

Combine Sanitary and Stormwater Sewer

1:2,397 ­

AOI3-3

AOI3-4

AOI3-5

AOI3-6

AOI3-3

Shallow Intermediate Deep

0 100 200 400

Feet

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

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

PROJECT

PFHxS Results (μg/Kg)

ND

>ND - 10

>10 - 130

>130 - 1,600

>1,600

AECOM 6-24
AOI1-2

AOI1-1

AOI1-3

AOI1-SS01

AOI1-SS03 AOI1-SS02

AOI1-SS04

AOI1-SS05

Figure 6-13

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Ochard Combat Training Center, ID

8/17/2022

8/17/2022

8/17/2022

MS

CH

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO,

USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri

8/17/2022

PFNA Detections in Soil, AOI 1

12420 Milestone Center Drive

Germantown, MD 20876

Legend

Facility Boundary

1:2,400 ­

AOI1-1

AOI1-3

AOI1-SS03

Shallow Intermediate

0 100 200 400

Feet

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

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

PROJECT

PFNA Results (μg/Kg)

ND

>ND - 19

>19 - 250

>250 - 2,500

>2,500

AECOM 6-25
AOI2-1

AOI2-3

AOI2-2

Figure 6-14

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Ochard Combat Training Center, ID

8/17/2022

8/17/2022

8/17/2022

MS

CH

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO,

USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri

8/17/2022

PFNA Detections in Soil, AOI 2

12420 Milestone Center Drive

Germantown, MD 20876

Legend

Facility Boundary

Combine Sanitary and Stormwater Sewer

1:1,200 ­

AOI2-1

AOI2-3

AOI2-2

AOI2-1

AOI2-3

Shallow Intermediate Deep

0 50 100 200

Feet

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

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

PROJECT

PFNA Results (μg/Kg)

ND

>ND - 19

>19 - 250

>250 - 2,500

>2,500

AECOM 6-26
AOI3-3

AOI3-4

AOI3-5

AOI3-6

Figure 6-15

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Ochard Combat Training Center, ID

10/4/2022

10/4/2022

10/4/2022

MS

CH

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO,

USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri

10/4/2022

PFNA Detections in Soil, AOI 3

12420 Milestone Center Drive

Germantown, MD 20876

Legend

Facility Boundary

Combine Sanitary and Stormwater Sewer

1:2,397 ­

AOI3-3

AOI3-4

AOI3-5

AOI3-6

AOI3-3

Shallow Intermediate Deep

0 100 200 400

Feet

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

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

PROJECT

PFNA Results (μg/Kg)

ND

>ND - 19

>19 - 250

>250 - 2,500

>2,500

AECOM 6-27
MPRCH-1

SRTF-1

Figure 6-16

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Ochard Combat Training Center, ID

10/4/2022

10/4/2022

10/4/2022

MS

CH

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO,

USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri

10/4/2022

PFOA Detections in Production Wells

12420 Milestone Center Drive

Germantown, MD 20876

Legend

1:67,200

Facility Boundary ­

1

ORTC-1

MATES-1

ASP-1

BRUMPTON-1

PFOA Results (ng/L)

ND

>ND - 6

>6 - 40

>40 - 70

>70

2 3

0 200 400 800

Feet

0 2,800 5,600 11,200

Feet

0 400 800 1,600

Feet

1

2

3

PROJECT

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

AECOM 6-28
MPRCH-1

SRTF-1

Figure 6-17

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Ochard Combat Training Center, ID

12/13/2022

12/13/2022

12/13/2022

MS

CH

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO,

USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri

12/13/2022

PFOS Detections in Production Wells

12420 Milestone Center Drive

Germantown, MD 20876

Legend

1:67,200

Facility Boundary ­

1

ORTC-1

MATES-1

ASP-1

BRUMPTON-1

PFOS Results (ng/L)

ND

>ND - 4

>4 - 40

>40 - 70

>70

2 3

0 200 400 800

Feet

0 2,800 5,600 11,200

Feet

0 400 800 1,600

Feet

1

2

3

PROJECT

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

AECOM 6-29
MPRCH-1

SRTF-1

Figure 6-18

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Ochard Combat Training Center, ID

10/5/2022

10/5/2022

10/5/2022

MS

CH

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO,

USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri

10/5/2022

PFBS Detections in Production Wells

12420 Milestone Center Drive

Germantown, MD 20876

Legend

1:67,200

Facility Boundary ­

1

ORTC-1

MATES-1

ASP-1

BRUMPTON-1

PFBS Results (ng/L)

ND

>ND - 100

>100 - 601

>601 - 2,000

>2,000

2 3

0 200 400 800

Feet

0 2,800 5,600 11,200

Feet

0 400 800 1,600

Feet

1

2

3

PROJECT

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

AECOM 6-30
MPRCH-1

SRTF-1

Figure 6-19

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Ochard Combat Training Center, ID

10/4/2022

10/4/2022

10/4/2022

MS

CH

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO,

USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri

10/4/2022

PFHxS Detections in Production Wells

12420 Milestone Center Drive

Germantown, MD 20876

Legend

1:67,200

Facility Boundary ­

1

ORTC-1

MATES-1

ASP-1

BRUMPTON-1

PFHxS Results (ng/L)

ND

>ND - 39

>39 - 100

>100 - 1,000

>1,000

2 3

0 200 400 800

Feet

0 2,800 5,600 11,200

Feet

0 400 800 1,600

Feet

1

2

3

PROJECT

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

AECOM 6-31
MPRCH-1

SRTF-1

Figure 6-20

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Ochard Combat Training Center, ID

10/4/2022

10/4/2022

10/4/2022

MS

CH

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO,

USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri

10/4/2022

PFNA Detections in Production Wells

12420 Milestone Center Drive

Germantown, MD 20876

Legend

1:67,200

Facility Boundary ­

1

ORTC-1

MATES-1

ASP-1

BRUMPTON-1

PFNA Results (ng/L)

ND

>ND - 6

>6 - 100

>100 - 1,000

>1,000

2 3

0 200 400 800

Feet

0 2,800 5,600 11,200

Feet

0 400 800 1,600

Feet

1

2

3

PROJECT

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

AECOM 6-32
AOI3-2

AOI3-1

Figure 6-21

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Ochard Combat Training Center, ID

10/4/2022

10/4/2022

10/4/2022

MS

CH

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO,

USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri

10/4/2022

PFOA, PFOS, and PFBS Detections in Sediment

12420 Milestone Center Drive

Germantown, MD 20876

Legend

Facility Boundary

Combine Sanitary and Stormwater Sewer

1:2,400 ­

AOI3-2

AOI3-1

AOI3-2

AOI3-1

PFOA

PFOA Results (μg/Kg)

ND

>ND - 19

>19 - 250

>250 - 2,500

>2,500

0 100 200 400

Feet

PFOS Results (μg/Kg)

ND

>ND - 13

>13 - 160

>160 - 1,600

>1,600

PFBS Results (μg/Kg)

ND

>ND - 10

>10 - 1,900

>1,900 - 25,000

>25,000

PFOS PFBS

PROJECT

AECOM 6-33
AOI3-2

AOI3-1

Figure 6-22

CLIENT

REVISED

SCALE

ARNG

Site Inspection at Ochard Combat Training Center, ID

10/4/2022

10/4/2022

10/4/2022

MS

CH

CM

GIS BY

CHK BY

PM

Base Map: Sources: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO,

USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri

10/4/2022

PFHxS and PFNA Detections in Sediment

12420 Milestone Center Drive

Germantown, MD 20876

Legend

Facility Boundary

Combine Sanitary and Stormwater Sewer

1:2,400 ­

AOI3-2

AOI3-1

PFHxS

PFHxS Results (μg/Kg)

ND

>ND - 10

>10 - 130

>130 - 1,600

>1,600

0 100 200 400

Feet

PFNA Results (μg/Kg)

ND

>ND - 19

>19 - 250

>250 - 2,500

>2,500

PFNA

PROJECT

AECOM 6-34
Site Inspection Report

Orchard Combat Training Center, Boise, Idaho

AECOM 7-1

7. Exposure Pathways

The conceptual site models (CSMs) for each AOI, revised based on the SI findings, are presented 

on Figure 7-1 through Figure 7-3. Please note that while the CSM discussion assists in 

determining if a receptor may be impacted, the decision to move from SI to RI or interim action is 

determined based upon exceedances of the SLs for the relevant compounds and whether the 

release is more than likely attributable to the DoD. A CSM presents the current understanding of 

the site conditions with respect to known and suspected sources, potential transport mechanisms 

and migration pathways, and potentially exposed human receptors. A human exposure pathway 

is considered potentially complete when the following conditions are present:

1. Contaminant source;

2. Environmental fate and transport;

3. Exposure point;

4. Exposure route; and

5. Potentially exposed populations.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

workers, trespassers, residents outside the facility boundary, and recreational users outside of 

the facility boundary.

7.1 Soil Exposure Pathway

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

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

aforementioned criteria.

7.1.1 AOI 1

Between 2014 and 2015, AFFF may have been released at AOI 1 during fire training activities. 

AFFF was used to extinguish controlled burns of vehicles three to six times at the Range 2 FTA. 

During fire training, flames were suppressed with water and 3% AFFF.
Site Inspection Report

Orchard Combat Training Center, Boise, Idaho

AECOM 7-2

PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in surface soil, and PFHxS was detected 

in subsurface soil at AOI 1. Site workers, construction workers, and trespassers could contact 

constituents in surface and subsurface soil via incidental ingestion and inhalation of dust.

Therefore, the surface and subsurface soil exposure pathway for site workers, future construction 

workers, and trespassers are potentially complete. The CSM for AOI 1 is presented on Figure 7-

1. 

7.1.2 AOI 2

From 2013 to 2017, nozzle testing and foam proportion testing were conducted on the surface 

soil directly northeast and southwest of and adjacent to the OCTC Fire Station. Additionally, 

approximately four AFFF-equipped firefighting backpacks and 20 to 30 gallons of 3% AFFF on a 

firetruck were stored at the OCTC Fire Station at the time of the PA (AECOM, 2020). PFOA, 

PFOS, and PFBS were detected in surface soil at AOI 2, at concentrations orders of magnitude 

below the SLs.

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

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

ingestion and inhalation of dust. Therefore, the surface soil exposure pathway for site workers, 

future construction workers, and trespassers are potentially complete. The CSM for AOI 2 is 

presented on Figure 7-2. 

7.1.3 AOI 3

AFFF released at the OCTC Fire Station may have been conveyed to AOI 3 via stormwater and 

sanitary drains. The lagoons are lined, and water has never been discharged from them, as the 

wastewater is left to evaporate. 

PFOA, PFOS, PFHxS, and PFBS were detected in surface soil whereas PFOS, PFHxS, and 

PFBS were detected in subsurface soil at AOI 3. PFNA was not detected in soil. Site workers, 

construction workers, and trespassers could contact constituents in surface and subsurface soil 

via incidental ingestion and inhalation of dust. Therefore, the surface and subsurface soil 

exposure pathway for site workers, future construction workers, and trespassers are potentially 

complete. The CSM for AOI 3 is presented on Figure 7-3.

7.2 Groundwater Exposure Pathway

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

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

7.2.1 Production Wells

Production wells across the facility were sampled as part of the SI. Data from these wells are 

used to evaluate groundwater exposure routes at all three AOIs.

PFOS was detected in two of six sampled production wells: BRUMPTON and SRTF. PFOS was

detected in groundwater at SRTF, at a concentration below the SL. PFOA, PFHxS, PFNA, and 

PFBS were not detected in any of the six production wells. The BRUMPTON well is located 

towards the southern facility boundary and approximately 10 miles south/southwest of the AOIs.

The SRTF well is located directly between AOI 1 and AOIs 2 and 3, and it is approximately 2 miles 

from each AOI. The production wells at the facility are used to supply the facility’s drinking water

and do not supply off-facility residents. Therefore, the exposure pathway for site workers via 

ingestion is potentially complete and the pathways for residents, trespassers, and recreational 

users are incomplete. Depths to water measured in July 2021 during the SI ranged from 423.2 to 
Site Inspection Report

Orchard Combat Training Center, Boise, Idaho

AECOM 7-3

775 feet bgs. Therefore, groundwater is too deep to be encountered during construction activities,

and the ingestion exposure pathway for construction workers is incomplete. The CSMs for AOI 1, 

AOI 2, and AOI 3 are presented on Figure 7-1 through Figure 7-3. 

7.3 Sediment Exposure Pathway

The SI results in surface water and sediment were used to determine whether a potentially 

complete pathway exists between the source and potential receptors at each AOI based on the 

aforementioned criteria. At AOIs where surface water and sediment samples were not collected, 

data from downgradient AOIs or the SI results in soil and groundwater, in combination with 

knowledge of the fate and transport properties of PFAS, were used to determine whether a 

potentially complete pathway exists between the source and potential receptors.

7.3.1 AOI 1

The closest surface water body is an unnamed stream over 2 miles west/northwest of AOI 1. 

While PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in soil at AOI 1, it is unlikely that 

PFAS migrated 2 miles via overland flow. Therefore, the surface water and sediment ingestion 

exposure pathway for all receptors are considered incomplete. The CSM for AOI 1 is presented 

on Figure 7-1.

7.3.2 AOI 2

AFFF released at AOI 2 may have drained into the stormwater and sanitary sewers, which flow 

into the Wastewater Lagoons. Consequently, surface water and sediment pathways for AOI 2 are 

evaluated as part of AOI 3. The CSM for AOI 2 is presented on Figure 7-2.

7.3.3 AOI 3

PFOA, PFOS, PFHxS, PFNA, and PFBS were detected in sediment samples collected from the 

southern wastewater lagoon at AOI 3. Surface water samples were not collected, but PFAS are 

water soluble and may have been leached from the sediment into the surface water. Based on 

the SI results, the ingestion pathway for surface water and sediment is potentially complete for 

future construction workers and trespassers. The lagoon system drains via evaporation, thus all 

pathways for off-facility receptors are incomplete. Site workers and trespassers are unlikely to 

access the Wastewater Lagoons as they are fenced and secured; therefore, the ingestion 

pathway is considered incomplete. The CSM for AOI 3 is presented on Figure 7-3.
Site Inspection Report

Orchard Combat Training Center, Boise, Idaho

AECOM 7-4

THIS PAGE INTENTIONALLY BLANK
Media

SOURCE PATHWAY RECEPTOR

AOI 1 Fire Training PFAS in 

Surface Soil

Human 

Activities

Precipitation/ 

Run-Off

Leaching/ 

Infiltration

Surface 

Water/ 

Sediment

Source Release 

Mechanism Media Transport and Migration Media Exposure Routes

Inhalation of 

Dust

Ingestion

Ingestion

Human Receptors: 

Current/ Future

Flow-Chart Continues

Partial / Possible Flow

Flow-Chart Stops

Incomplete Pathway

Potentially Complete Pathway

Potentially Complete Pathway 

with Exceedance

Site Worker Construction Worker Resident1,2 Trespasser/ Recreational User1,2

Site Worker Construction Worker Resident1,2 Trespasser/ Recreational User1,2

/ / / /

/ /

LEGEND

/ /

/ /

/

/

/

/

/

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

/

Figure 7-1

Conceptual Site Model, AOI 1

Orchard Combat Training Center, Idaho

NOTES

1. The resident and recreational users

refer to off-site receptors.

2. Inhalation of dust for off-site receptors

is likely insignificant.

3. Groundwater pathways are assessed

using facility-wide groundwater data.

/

Groundwater / 3 Subsurface 

Soil

Surface Soil 

at AOI

Airborne Soil 

Particulate

/

/

Ingestion

Ingestion

7-5
Media

SOURCE PATHWAY RECEPTOR

AOI 2 Nozzle Testing PFAS in 

Surface Soil

Human 

Activities

Precipitation/ 

Run-Off

Leaching/ 

Infiltration

Surface 

Water/ 

Sediment3

Source Release 

Mechanism Media Transport and Migration Media Exposure Routes

Inhalation of 

Dust

Ingestion

Ingestion

Ingestion

Human Receptors: 

Current/ Future

Flow-Chart Continues

Partial / Possible Flow

Flow-Chart Stops

Incomplete Pathway

Potentially Complete Pathway

Potentially Complete Pathway 

with Exceedance

Site Worker Construction Worker Resident1,2 Trespasser/ Recreational User1,2

Site Worker Construction Worker Resident1,2 Trespasser/ Recreational User1,2

/ /

LEGEND

/ /

/ /

/

Figure 7-2

Conceptual Site Model, AOI 2

Orchard Combat Training Center, Idaho

/

/

/

/

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

/

/

NOTES

1. The resident and recreational users

refer to off-site receptors.

2. Inhalation of dust for off-site receptors

is likely insignificant.

3. Surface water and sediment

pathways evaluated with AOI 3.

4. Groundwater pathways are assessed

using facility-wide groundwater data.

Groundwater4 Subsurface 

Soil

Surface Soil 

at AOI

Airborne Soil 

Particulate

/ / / /

/

/

/

Ingestion

7-6
Media

SOURCE PATHWAY RECEPTOR

AOI 3

Drainage from 

the combined 

sanitary and 

wastewater sewer PFAS in 

surface soil 

at AOI 2

Human 

Activities

Precipitation/ 

Run-Off

Leaching/ 

Infiltration

Surface 

Water/ 

Sediment

Source Release 

Mechanism Media Transport and Migration Media Exposure Routes

Inhalation of 

Dust

Ingestion

Ingestion

Ingestion

Ingestion

Human Receptors: 

Current/ Future

Flow-Chart Continues

Partial / Possible Flow

Flow-Chart Stops

Incomplete Pathway

Potentially Complete Pathway

Potentially Complete Pathway 

with Exceedance

Site Worker Construction Worker Resident1,2 Trespasser/ Recreational User1,2

Site Worker Construction Worker Resident1,2 Trespasser/ Recreational User1,2

/ /

LEGEND

/

Figure 7-3

Conceptual Site Model, AOI 3

Orchard Combat Training Center, Idaho

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

/

/

/

/

/ /

/

Groundwater3

/

/ /

/

/

NOTES

1. The resident and recreational users

refer to off-site receptors.

2. Inhalation of dust for off-site receptors

is likely insignificant.

3. Groundwater pathways are assessed

using facility-wide groundwater data.

Subsurface 

Soil

Surface Soil 

at AOI

Airborne Soil 

Particulate

/ /

/

/

/

7-7
Site Inspection Report

Orchard Combat Training Center, Boise, Idaho

THIS PAGE INTENTIONALLY BLANK

AECOM 
Site Inspection Report

Orchard Combat Training Center, Boise, Idaho

AECOM 8-1

8. Summary and Outcome

This section summarizes SI activities and findings. The most significant findings are summarized 

in this section and are reproduced directly or abstracted from information contained in this report. 

The outcome provides general and comparative interpretations of the findings relative to the SLs.

8.1 SI Activities

The SI field activities were conducted from 26 to 30 July 2021 and consisted of utility clearance, 

direct push boring, soil sample collection, sediment sample collection, groundwater sample 

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

Addendum (AECOM, 2021a), except as previously noted in Section 5.9. 

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

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

Table B-15 as follows. 

• Twenty-eight (28) soil samples from 15 boring locations; 

• Six groundwater samples from six pre-existing production well locations; 

• Two sediment samples from two locations; and

• Twenty (20) QA/QC samples.

An SI is conducted when the PA determines an AOI exists based on probable use, storage, and/or 

disposal of PFAS-containing materials. The SI includes multi-media sampling at AOIs to 

determine whether or not a release has occurred. The SI may conclude further investigation is 

warranted, a removal action is required to address immediate threats, or no further action is 

required. Additionally, the CSMs were refined to assess whether a potentially complete pathway 

exists between the source and potential receptors for potential exposure at the AOIs, which are 

described in Section 7.

8.2 Outcome 

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

three AOIs at this time. Based on the CSMs developed and revised in light of the SI findings, there 

is potential for exposure to drinking water receptors from production wells from sources on the

facility resulting from historical DoD activities. Sample analytical concentrations collected during 

the SI were compared to the project SLs in soil and groundwater, as described in Table 6-1. A 

summary of the results of the SI data relative to the SLs is as follows:

• At AOI 1:

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

AOI 1 were below their SLs. Based on the results of the SI, no further evaluation of 

AOI 1 is warranted.

• At AOI 2:

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

AOI 2 were below their SLs. Based on the results of the SI, no further evaluation of 

AOI 2 is warranted.
Site Inspection Report

Orchard Combat Training Center, Boise, Idaho

AECOM 8-2

• At AOI 3: 

• The detected concentrations of PFOA, PFOS, PFHxS, and PFBS in soil at AOI 3 

were below their SLs. PFNA was not detected. Based on the results of the SI, no 

further evaluation of AOI 3 is warranted. 

• At Production Wells: 

• PFOS was detected in two of six sampled production wells: the BRUMPTON well 

and the SRTF well, at concentrations below its SL. PFOA, PFHxS, PFNA, and PFBS

were not detected in any of the six production wells. Based on the results of the SI, 

no further evaluation of the SRTF and BRUMPTON production wells is warranted at 

this time. However, in accordance with Army guidance, because PFOS was detected 

in two of the production wells above the method reporting limit, but below the health 

advisory level, IDARNG will sample the production wells quarterly for one year and 

once every two years thereafter until the results are below the method reporting limits. 

This will allow IDARNG to monitor and evaluate any changes in the drinking water 

pathway at OCTC. 

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

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

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

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

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

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

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

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

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

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

AOI Potential 

Release Area

Soil –

Source 

Area

Groundwater – 

Source Area

Groundwater – 

Facility Boundary

Future 

Action

1 Range 2 FTA NA

No 

further 

action

2 OCTC Fire 

Station NA

No 

further 

action

3 Wastewater 

Lagoons NA

No 

further 

action

Production 

Wells SRTF-1 Unknown

No 

further 

action

Legend:

= detected; exceedance of the screening levels

= detected; no exceedance of the screening levels

= not detected
Site Inspection Report

Orchard Combat Training Center, Boise, Idaho

AECOM 9-1

9. References 

AECOM. 2018a. Final Site Inspection Programmatic Uniform Federal Policy-Quality Assurance 

Project Plan, Perfluorooctane Sulfonic Acid (PFOS) and Perfluorooctanoic Acid (PFOA) 

Impacted Sites ARNG Installations, Nationwide Contract No. W912DR-12-D-0014/

W912DR17F0192. 9 March.

AECOM. 2018b. Final Programmatic Accident Prevention Plan, Perfluorooctane Sulfonic Acid 

(PFOS) and Perfluorooctanoic Acid (PFOA) Impacted Sites ARNG Installations, Nationwide 

Contract No. W912DR-12-D-0014/W912DR17F0192. July.

AECOM. 2020. Final Preliminary Assessment Report, Orchard Combat Training Center, Boise, 

Idaho. February. 

AECOM. 2021a. Final Site Inspection Uniform Federal Policy-Quality Assurance Project Plan 

Addendum, Orchard Combat Training Center, Boise, Idaho, Perfluorooctane Sulfonic Acid 

(PFOS) and Perfluorooctanoic Acid (PFOA) Impacted Sites ARNG Installations, Nationwide. 

May.

AECOM. 2021b. Final Site Safety and Health Plan, Orchard Combat Training Center, Boise, 

Idaho, Perfluorooctane Sulfonic Acid (PFOS) and Perfluorooctanoic Acid (PFOA) Impacted 

Sites ARNG Installations, Nationwide. July.

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

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

6 July. 

Boise State University & IDARNG. 2013. Integrated Cultural Resources Management Plan 

Revision for Site and Training Installations of the Idaho Army National Guard Fiscal Years 

2013-2017. January.

DA. 2018. Army Guidance for Addressing Releases of Per- and Polyfluoroalkyl Substances. 

4 September.

DoD. 2019a. Department of Defense (DoD), Department of Energy (DOE) Consolidated Quality 

Systems Manual (QSM) for Environmental Laboratories, Version 5.3. 

DoD. 2019b. General Data Validation Guidelines. Environmental Data Quality Workgroup. 

4 November.

EA Engineering, Science, and Technology, Inc. 2021. Standard Operating Procedure No. 042A 

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

decontamination fluids). Revision 1. March.

Guelfo, J.L. and Higgins, C.P. 2013. Subsurface Transport Potential of Perfluoroalkyl Acids at 

Aqueous Film-Forming Foam (AFFF)-Impacted Sites. Environmental Science and Technology 

47(9): 4164-71.

Higgins, C.P., and Luthy, R.G. 2006. Sorption of perfluorinated surfactants on 

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

IDARNG. 2018. Draft Environmental Assessment for the Proposed Digital Air-Ground 

Integration Range (DAGIR) Within the Orchard Combat Training Center’s Impact Area. 

August.

IDNG EMO. 2013. Integrated Natural Resources Management Plan (Final) Orchard Combat 

Training Center Idaho Army National Guard. January.
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Orchard Combat Training Center, Boise, Idaho

AECOM 9-2

IDWR. 2019. Idaho Department of Water Resources Map and GIS Data Hub. Accessed March 

2019 at https://data-idwr.opendata.arcgis.com/pages/popular-maps.

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

National Oceanic and Atmospheric Administration (NOAA). National Centers for Environmental 

Information Data. Accessed May 2022 at https://www.ncdc.noaa.gov/cdoweb/datatools/normals. 

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

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

(CERCLA). 

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

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

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

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

Assessments). December.

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

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

Innovation. January.

USFWS. 2022. Species by County Report, County: Ada, Idaho. Environmental Conservation 

Online System. Accessed 16 September 2022 at https://ecos.fws.gov/ecp/report/specieslistings-by-current-range-county?fips=16001. 

USGS. 1992. US Geological Survey Professional Paper 1408-B. Geohydrologic Framework of 

the Snake River Plain Regional Aquifer System, Idaho and Eastern Oregon. 

USGS. 1996. US Geological Survey Professional Paper 1408-A. Summary of the Snake River 

Plain Regional Aquifer-System Analysis in Idaho and Eastern Oregon. 

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

and perfluorooctanoate (PFOA) in soils and groundwater of a U.S. metropolitan area: 

Migration and implications for human exposure. Water Research 72: 64-74.