Army National Guard Headquarters 

111 S. George Mason Drive

Arlington, VA 22204

US Army Corps of Engineers, Baltimore District

2 Hopkins Plaza

Baltimore, MD 21201

Prepared by:

AECOM

12420 Milestone Center Drive, Suite 150

Germantown, MD 20876

aecom.com

Contract Number: W912DR-12-D-0014

Delivery Order: W912DR17F0192

Final 

Preliminary Assessment Report

Edgemeade Mountain Home 

Training Site 

Mountain Home, Idaho 

Perfluorooctane-Sulfonic Acid (PFOS) and Perfluorooctanoic 

Acid (PFOA) Impacted Sites

ARNG Installations, Nationwide

March 2020

Prepared for:
PFAS Preliminary Assessment Report

Edgemeade Mountain Home Training Site 

Mountain Home, ID

i 

Table of Contents

Executive Summary................................................................................................................. 1

1. Introduction .................................................................................................................... 3

1.1 Authority and Purpose ........................................................................................... 3

1.2 Preliminary Assessment Methods........................................................................... 3

1.3 Report Organization............................................................................................... 4

1.4 Facility Location and Description............................................................................ 4

1.5 Facility Environmental Setting................................................................................ 4

1.5.1 Geology...................................................................................................... 5

1.5.2 Hydrogeology.............................................................................................. 5

1.5.3 Hydrology ................................................................................................... 6

1.5.4 Climate ....................................................................................................... 6

1.5.5 Current and Future Land Use ...................................................................... 6

2. Fire Training Areas........................................................................................................ 10

3. Non-Fire Training Areas.................................................................................................11

4. Emergency Response Areas......................................................................................... 12

5. Adjacent Sources ......................................................................................................... 13

6. Conceptual Site Model.................................................................................................. 14

7. Conclusions.................................................................................................................. 15

7.1 Findings .............................................................................................................. 15

7.2 Uncertainty.......................................................................................................... 15

7.3 Potential Future Actions....................................................................................... 15

8. References................................................................................................................... 17

Figures 

Figure ES-1 Summary of Findings

Figure 1-1 Facility Location

Figure 1-2 Groundwater Features

Figure 1-3 Surface Water Features

Figure 7-1 Summary of Findings

Appendices 

Appendix A Data Resources

Appendix B Preliminary Assessment Documentation

 B.1 Interview Records

 B.2 Visual Site Inspection Checklists

 B.3 Conceptual Site Model Information

Appendix C Photographic Log
PFAS Preliminary Assessment Report

Edgemeade Mountain Home Training Site 

Mountain Home, ID

iii 

Acronyms and Abbreviations

AECOM AECOM Technical Services, Inc.

AFFF aqueous film forming foam

amsl above mean sea level

AOI area of interest

ARNG

BLM

Army National Guard

Bureau of Land Management

CERCLA Comprehensive Environmental Response, Compensation, and Liability 

Act

CFR Code of Federal Regulations

CSM conceptual site model

FTA

IDARNG

fire training area

Idaho Army National Guard

IED Installations and Environment Division

PA Preliminary Assessment

PFAS per- and poly-fluoroalkyl substances

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

SI Site inspection

US United States

USACE United States Army Corps of Engineers

USEPA United States Environmental Protection Agency

VSI visual site inspection
PFAS Preliminary Assessment Report

Edgemeade Mountain Home Training Site 

Mountain Home, ID

1

Executive Summary

The United States (US) Army Corps of Engineers (USACE) Baltimore District on behalf of the 

Army National Guard (ARNG)-Installations & Environment Division (IED), Cleanup Branch 

contracted AECOM Technical Services, Inc. (AECOM) to perform Preliminary Assessments 

(PAs) and Site Inspections (SIs) for Perfluorooctanesulfonic acid (PFOS) and Perfluorooctanoic 

acid (PFOA) Impacted Sites at ARNG Facilities Nationwide. The ARNG is assessing potential 

effects on human health related to processes at facilities that used per- and poly-fluoroalkyl 

substances (PFAS) (a suite of related chemicals), primarily in the form of aqueous film forming 

foam (AFFF) released during firefighting activities or training, although other PFAS sources are 

possible. In addition, the ARNG is assessing businesses or operations adjacent to the ARNG 

facility (not under the control of ARNG) that could potentially be responsible for a PFAS release.

AECOM completed a PA for PFAS at the Idaho (ID) ARNG Edgemeade Mountain Home 

Training Site in Mountain Home, ID to assess potential PFAS release areas and exposure 

pathways to receptors. The performance of this PA included the following tasks:

• Reviewed data resources to obtain information relevant to suspected PFAS releases

• Conducted a 1-day site visit on 25 February 2019

• Interviewed current IDARNG personnel during the site visit, which included operations staff

• Completed visual site inspections (VSIs) at any potential PFAS release locations and

documented with photographs

No areas of interest (AOIs) related to PFAS releases were identified at Edgemeade Mountain 

Home Training Site based on PA data. The summary of PA findings is shown on Figure ES-1. 

Based on the absence of documented use/releases of PFAS-containing materials at

Edgemeade Mountain Home Training Site, evidence does not support current or former ARNG 

activities having contributed to PFAS contamination in soil, groundwater, surface water, or 

sediment at the facility. The facility will not move forward in the CERCLA process. 
CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

PD

6/19/2019

6/19/2019

NOTES Preliminary Assessment for PFAS at Edgemead Mtn HTS, ID

1:6,000

6/19/2019 ­ Figure ES-1 PM RG 6/19/2019

12420 Milestone Center Drive

Germantown, MD 20876

Summary of Findings

Base Map: Source: Esri, DigitalGlobe, GeoEye,

Earthstar Geographics, CNES/Airbus DS, USDA, USGS,

Q:\Projects\ENV\GEARS\GEO\ARNG PFAS\900-CAD-GIS\920-GIS or Graphics\MXD\ID\Edgemead_Mtn_HTS_Figures\Edgemead_Mtn_HTS_PA_Figures\Fig_ES-1_Edgemead_Mtn_HTS_Summary.mxd

Legend

No Suspected Release

Facility Boundary

River/Stream

0 250 500 1,000

Feet

2
PFAS Preliminary Assessment Report

Edgemeade Mountain Home Training Site 

Mountain Home, ID

3

1. Introduction

1.1 Authority and Purpose

The United States (US) Army Corps of Engineers (USACE) Baltimore District on behalf of the 

Army National Guard (ARNG)-Installations & Environment Division (IED), Cleanup Branch 

contracted AECOM Technical Services, Inc. (AECOM) to perform Preliminary Assessments 

(PAs) and Site Inspections (SIs) for Perfluorooctanesulfonic acid (PFOS) and Perfluorooctanoic 

acid (PFOA) Impacted Sites at ARNG Facilities Nationwide under Contract Number W912DR12-D-0014, Task Order W912DR17F0192, issued 11 August 2017. The ARNG is assessing

potential effects on human health related to processes at their facilities that used per- and polyfluoroalkyl substances (PFAS) (a suite of related chemicals), primarily releases of aqueous film 

forming foam (AFFF) released during firefighting activities or training, although other sources of 

PFAS are possible. In addition, the ARNG is assessing businesses or operations adjacent to the 

ARNG facility (not under the control of ARNG) that could potentially be responsible for a PFAS 

release. 

PFAS are classified as emerging environmental contaminants that are garnering increasing 

regulatory interest due to their potential risks to human health and the environment. PFAS 

formulations contain highly diverse mixtures of compounds. Thus, the fate of PFAS compounds 

in the environment varies. The regulatory framework at both federal and state levels continues 

to evolve. The US Environmental Protection Agency (USEPA) issued Drinking Water Health 

Advisories for PFOA and PFOS in May 2016, but there are currently no promulgated national 

standards regulating PFAS in drinking water. In the absence of federal maximum contaminant 

levels, some states have adopted their own drinking water standards for PFAS. The state of 

Idaho does not currently have promulgated standards for PFAS in drinking water.

This report presents findings of a PA for PFAS at the IDARNG Edgemeade Mountain Home 

Training Site (also referred to as “the installation”) in Mountain Home, ID, in accordance with the 

Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), as 

amended, the National Oil and Hazardous Substances Pollution Contingency Plan (40 Code of 

Federal Regulations [CFR] Part 300), and USACE requirements and guidance.

This PA Report documents the potential locations where PFAS may have been released into the 

environment at or adjacent to the Edgemeade Mountain Home Training Site. The term PFAS will 

be used throughout this report to encompass all PFAS chemicals being evaluated, including 

PFOS and PFOA, which are key components ofAFFF. 

1.2 Preliminary Assessment Methods

The performance of this PA included the following tasks: 

• Reviewed data resources to obtain information relevant to suspected PFAS releases

• Conducted a 1-day site visit on 25 February 2019

• Interviewed personnel associated with Edgemeade Mountain Home Training Site

• Completed visual site inspections (VSIs) at any possible PFAS release locations and

documented with photographs 

• If areas of interest (AOIs) were identified, developed a conceptual site model (CSM) to

outline the potential release and pathway of PFAS for each AOI
PFAS Preliminary Assessment Report

Edgemeade Mountain Home Training Site 

Mountain Home, ID

4

1.3 Report Organization

This report has been prepared in accordance with the USEPA Guidance for Performing 

Preliminary Assessments under CERCLA (USEPA, 1991). The report sections and descriptions 

of each are:

• Section 1 – Introduction: identifies the project purpose and authority and describes the

facility location, environmental setting, and methods used to complete the PA.

• Section 2 – Fire Training Areas: describes the FTAs at the facility identified during the site

visit. 

• Section 3 – Non-Fire Training Areas: describes other locations of PFAS releases at the

facility identified during the site visit. 

• Section 4 – Emergency Response Areas: describes areas of AFFF release at the facility,

specifically in response to emergency situations. 

• Section 5 – Adjacent Sources: describes sources of PFAS release adjacent to the facility

that are not under the control of ARNG. 

• Section 6 – Conceptual Site Model: describes the pathways of PFAS transport and

receptors at each AOI. 

• Section 7 – Conclusions: summarizes the data findings and presents the conclusions of

the PA. 

• Section 8 – References: provides the references used to develop this document.

• Appendix A – Data Resources

• Appendix B – Preliminary Assessment Documentation

• Appendix C – Photographic Log

1.4 Facility Location and Description

The IDARNG Edgemeade Mountain Home Training Site is located about 2 miles east of the 

center of Mountain Home, ID (Figure 1-1), and is owned by the IDARNG. The installation 

consists of a 150.09-acre parcel of land with rolling, open terrain with ephemeral drainage 

channels (North Wind, 2010). The town of Mountain Home is located approximately 42 miles to 

the southeast of Boise, ID in the Snake River Valley. Interstate Highway 84 is 0.7 miles to the 

west, and the Mountain Home Reservoir is 1.2 miles to the north-northwest.

The property operated as a juvenile detention center from the 1960s until the 1990s. The 

IDARNG has been operating Edgemeade Mountain Home Training Site since the 1990s. The 

installation consists of two occupied buildings, with very few daily employees. High school 

students and approximately 70 members of the military attend academic classes and training 

activities on-site.

Regular operations at the installation include administrative work, flight simulations, academic 

classes, mine simulation training, and drilling activities. The main hangar was built in 2014. 

1.5 Facility Environmental Setting

The Edgemeade Mountain Home Training Site is located at the gently sloping base of the 

Bennett Hills area and near the northern edge of the Snake River Basin. The Snake River lies 

about 13 miles south of the installation. The topography slopes gently to the west with 
PFAS Preliminary Assessment Report

Edgemeade Mountain Home Training Site 

Mountain Home, ID

5

elevations between 3,300 feet (ft) above mean sea level (amsl) – 3,400 ft amsl. The installation 

lies within the Snake River Birds of Prey National Conservation Area, which is managed by the 

BLM and is home to over 700 pairs of nesting raptors (North Wind, 2010).

1.5.1 Geology

The Edgemeade Mountain Home Training Site is located in the western portion of the Snake 

River Plain, which extends approximately 400 miles east to west across southern Idaho. The 

Snake River Plain is a structurally controlled, fault-bounded basin which was driven by hot spot 

volcanic activity. In the western part of the plain, volcanic extrusions alternated with deposition 

of fluvial and lacustrine sediments during the early geologic history of the basin (USGS, 1996). 

Lacustrine fine-grained sediments of the Chalk Hills Formation, which are evidence of ancient 

Lake Idaho, are separated from the overlying pebbly and oolitic sands by an erosional surface 

(Wood & Clemens, 2002). Cobble, gravel, and sand deposits from the early Snake River and 

basaltic volcanic deposits make up the present day surficial geology in the western Snake River 

Plain. Much of these volcanic deposits are manifested as fields of dormant shield volcanos that 

trend with a NW to SW strike, likely related to the fault structure in this area (Wood & Clemens, 

2002). 

The surficial geologic map of the Edgemeade Mountain Home Training Site area shows basalt 

flows of Pleistocene to Pliocene age covered by 3 – 10 ft of loess (IGS, 2019). Quaternary 

alluvial deposits lie to the west, and alluvial fan and bedrock deposits exist at the surface to the 

east (Figure 1-2). 

1.5.2 Hydrogeology

Groundwater near the town of Mountain Home exists in two aquifers. The first is a shallow, 

perched aquifer found primarily in alluvium deposits of Quaternary age. Depth to water in the 

perched system varies and can be found as shallow as 10 ft below ground surface (bgs) (IDEQ, 

1996). Data from the Idaho Department of Water Resources list three wells just outside of the 

northwest corner of the installation boundary, and one well within 0.5 miles of the western edge 

of the installation. The static water depths in these wells range between 102 to 198 ft bgs. 

The deeper, regional aquifer provides water for municipal irrigation wells in the Mountain Home 

area. The most productive zones of this aquifer occur within basalt flows of the Bruneau 

Formation of the Idaho Group. Depth to water in the deep, regional aquifer varies between 200 

to 400 ft bgs. Recharge to the regional aquifer occurs through precipitation on the volcanic 

mountains to the north of Mountain Home, through infiltration from the ephemeral streams in the 

area, and through percolation from the shallow perched aquifer. The perched aquifer recharges 

through percolation from Mountain Home Reservoir, local creeks, and various irrigation canals. 

The Idaho Department of Water Resources Geographic Information System (GIS) Application 

maps wells within the Mountain Home area with water levels ranging from 100 to over 200 ft bgs 

(IDWR, 2019).

Groundwater flow in both aquifers is generally to the south/southwest (Figure 1-2). 

Groundwater levels near Mountain Home fluctuate up to 10 ft seasonally as a result of irrigation 

in the local area (IDEQ, 1996).

The municipal water supply for the town of Mountain Home comes from wells drilled to depths of 

800 to 1,000 ft bgs, each producing roughly 600 to 2,100 gallons per minute. The Edgemeade 

Mountain Home Training Site is supplied by this municipal water source. The EDR (Appe ndix 

A) shows a municipal supply well located approximately 2,730 feet to the northwest of the

Edgemeade Mountain Home Training Center buildings.
PFAS Preliminary Assessment Report

Edgemeade Mountain Home Training Site 

Mountain Home, ID

6

1.5.3 Hydrology

Edgemeade Mountain Home Training Site is located within the CJ Strike Reservoir – Snake 

River watershed, which is within the Middle Snake sub-basin. This sub-basin covers 1,281,280 

acres of semi-arid land in the greater Snake River basin. Drainage in this basin is characterized 

by low-volume rangeland streams that run through sagebrush steppe country (IDEQ, 2019).

There is no surface water present within the boundaries of the Edgemeade Mountain Home 

Training Site. Drainage at the site is ephemeral. The Snake River flows about 13 miles to the 

south of the installation, and the Mountain Home Reservoir, which was formed by impoundment 

of Rattlesnake Creek, is approximately 1.2 miles to the north-northwest. There is no direct 

connection between the installation and these surface water features (North Wind, 2010).

Figure 1-3 depicts the surface water features in the Edgemeade Mountain Home Training Site 

area. 

1.5.4 Climate

The climate at the site and surrounding area is characterized as semiarid. Winds are typically 

low, averaging less than 10 miles per hour. The average precipitation in Mountain Home is 

10.55 inches, with the majority of precipitation falling from November to March. The average 

annual temperature is about 51.4° F, with highs in the summer around 89.7° F and lows in the 

winter around 22.8° F (NOAA, 2019). 

1.5.5 Current and Future Land Use

The Edgemeade Mountain Home Training Site is used for administrative work, flight simulations, 

academics, training, and drilling. The training mostly consists of mine identification and vehicle 

maneuvering. There are no current expansion plans for the facility and, in general, the future 

use of the facility is not expected to change.
CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

PD

4/24/2019

4/24/2019

NOTES Preliminary Assessment for PFAS at Edgemead Mtn HTS, ID

1:126,720

4/24/2019 ­ Figure 1-1 PM RG 4/24/2019

12420 Milestone Center Drive

Germantown, MD 20876

Facility Location Map

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

Intermap, increment P Corp., NRCAN, Esri Japan, METI,

Q:\Projects\ENV\GEARS\GEO\ARNG PFAS\900-CAD-GIS\920-GIS or Graphics\MXD\ID\Edgemead_Mtn_HTS_Figures\Edgemead_Mtn_HTS_PA_Figures\Fig_1-1_Edgemead_Mtn_HTS_Facility_Location.mxd

Legend

Facility Boundary

0 1 2 4

Miles

Edgemead Mountain

Home Training Site

^_

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Ra ttlesnak e C reek

Canyon Creek

East Side Canal

Mill er Canal

Lamberton Canal

West Side Canal

Feeder Canal

CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

PD

5/2/2019

5/2/2019

NOTES Preliminary Assessment for PFAS at Edgemead Mtn HTS, ID

1:63,360

5/2/2019 ­ Figure 1-2 PM RG 5/2/2019

12420 Milestone Center Drive

Germantown, MD 20876

Groundwater Features

Base Map: Source: Esri, DigitalGlobe, GeoEye,

Earthstar Geographics, CNES/Airbus DS, USDA, USGS,

Q:\Projects\ENV\GEARS\GEO\ARNG PFAS\900-CAD-GIS\920-GIS or Graphics\MXD\ID\Edgemead_Mtn_HTS_Figures\Edgemead_Mtn_HTS_PA_Figures\Fig_1-2_Edgemead_Mtn_HTS_Groundwater.mxd

Legend

Facility Boundary

Water Body

River/Stream

Canal/Ditch

Inferred Groundwater Flow

Direction

Geology

 Alluvial Deposits

(Quaternary)

Basalt (Pleistocene and

Pliocene)

Wells

!P Domestic Well

!5 Irrigation Well

!C( Municipal/Public Water

Supply Well

A! Monitoring Well

A! Other/Unknown Well

0 0.5 1 2

Miles

Mountain 

Home

Reservoir

8
Ra t tlesnake Cr eek

Canyon Creek

East Side

Canal

Mill er Canal

Lamberton Canal

West Side Canal

Feeder Canal

East Side

Canal

Watershed

Clover

Hollow

Watershed

Rattlesnake

Creek

Watershed

Upper Canyon

Creek

Watershed

Headwaters

Rattlesnake

Creek Watershed

CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

PD

5/2/2019

5/2/2019

NOTES Preliminary Assessment for PFAS at Edgemead Mtn HTS, ID

1:63,360

5/2/2019 ­ Figure 1-3 PM RG 5/2/2019

12420 Milestone Center Drive

Germantown, MD 20876

Surface Water Features

Base Map: Source: Esri, DigitalGlobe, GeoEye,

Earthstar Geographics, CNES/Airbus DS, USDA, USGS,

Q:\Projects\ENV\GEARS\GEO\ARNG PFAS\900-CAD-GIS\920-GIS or Graphics\MXD\ID\Edgemead_Mtn_HTS_Figures\Edgemead_Mtn_HTS_PA_Figures\Fig_1-3_Edgemead_Mtn_HTS_Surface_Water.mxd

Legend

Facility Boundary

Water Body

River/Stream

Canal/Ditch

Surface Water Flow

Direction

0 0.5 1 2

Miles

Mountain 

Home

Reservoir

9
PFAS Preliminary Assessment Report

Edgemeade Mountain Home Training Site 

Mountain Home, ID

10

2. Fire Training Areas

No FTAs were identified at the IDARNG Edgemeade Mountain Home Training Site during the 

PA. Staff at the installation reported no knowledge of a fire department on-site from 2013 to 

present. Aerial photos from the EDR report show a steady removal of buildings from the

beginning of IDARNG operations in the 1990s until 2013, with no apparent new construction or 

building renovations. Therefore, it is unlikely that the IDARNG built or retrofitted a fire station 

and maintained a fire department during this time.
PFAS Preliminary Assessment Report

Edgemeade Mountain Home Training Site 

Mountain Home, ID

11

3. Non-Fire Training Areas

No non-FTAs with potential AFFF releases were identified at the IDARNG Edgemeade Mountain 

Home Training Site during the PA. According to interviews with staff at the installation, the 

IDARNG has not stored, mixed, or used AFFF at the Edgemeade Mountain Home Training Site

from at least 2013 to present. Based upon the reported historic use of the installation and review 

of the EDR report, it is unlikely that AFFF was present on-site from the 1990s to 2013. 
PFAS Preliminary Assessment Report

Edgemeade Mountain Home Training Site 

Mountain Home, ID

12

4. Emergency Response Areas

No instances of emergency response firefighting were identified at the IDARNG Edgemeade 

Mountain Home Training Site during the PA. Fire suppression systems in the buildings carry 

water, and all fire extinguishers on-site were identified as ABC rated (non-AFFF).

In the event that firefighting support is needed at Edgemeade Mountain Home Training Site, the 

local Mountain Home Fire Department would respond. None of the staff interviewed during the 

PA site visit were aware of any event at the installation in which the Mountain Home Fire 

Department responded. It was not determined what type of fire suppression the local fire 

department uses or has used in the past.
13

PFAS Preliminary Assessment Report

Edgemeade Mountain Home Training Site 

Mountain Home, ID

5. Adjacent Sources

Based on interviewee knowledge and review of the EDR report, no off-facility PFAS sources 

adjacent to the Edgemeade Mountain Home Training Site were identified during the PA.
PFAS Preliminary Assessment Report

Edgemeade Mountain Home Training Site 

Mountain Home, ID

14

6. Conceptual Site Model

Based on the PA findings, no PFAS release areas are likely to have occurred, thus, no AOIs 

were identified at the Edgemeade Mountain Home Training Site. A CSM identifies three 

components necessary for potentially complete exposure pathways related to a site: (1) source, 

(2) pathway, and (3) receptor. If any of these elements are missing, the pathway is considered

incomplete. Based on the findings of this PA, no PFAS sources originate at the Edgemeade 

Mountain Home Training Site or from activities associated with the installation. No complete 

exposure pathway for PFAS has been identified at the installation or the surrounding 

community. 
PFAS Preliminary Assessment Report

Edgemeade Mountain Home Training Site 

Mountain Home, ID

15

7. Conclusions

This report presents a summary of available information gathered during PA efforts on the use 

and storage of AFFF at Edgemeade Mountain Home Training Site. The PA findings are based 

on personnel interviews, historical reports, historical documents, and the VSI. 

7.1 Findings

No AOIs related to PFAS releases were identified at Edgemeade Mountain Home Training Site

based on PA data. Based on the absence of AFFF releases or spills at the Edgemeade 

Mountain Home Training Site, evidence does not support the potential for PFAS contamination 

in soil, groundwater, surface water, or sediment for any receptor. 

A summary of PA findings is presented in Figure 7-1. 

7.2 Uncertainty

A number of information sources were investigated during this PA to determine the potential for 

PFAS-containing materials to have been present, used, or released at the facility. Historically, 

documentation of PFAS use was not required because PFAS were considered benign. 

Therefore, records on the use of PFAS in training, other non-traditional activities, or on its 

disposition were not typically kept by the facility or available during the PA. 

The conclusions of this PA are predominantly based on the information provided during 

interviews with personnel who had direct knowledge on whether PFAS was used at the facility. 

Gathered information has a degree of uncertainty due to the absence of written documentation, 

the limited number of personnel with direct knowledge due to staffing changes, the time passed 

since PFAS was first used (early 1970s), and a reliance on personal recollection. There is also a 

possibility the PA has missed a source of PFAS, as the science of how PFAS may enter the 

environment continually evolves. 

Information on the operations at Edgemeade during ownership by the juvenile detention center 

was not obtained. No personnel with direct knowledge of operations at the installation from the 

1990s until 2013 were available for interview. However, it is unlikely that any PFAS-producing 

activities were conducted as a part of those historical operations. 

No AOIs were identified at Edgemeade Mountain Home Training Site. Based on the historical 

and current use of the facility, minimal uncertainty is associated with the findings of this PA.

7.3 Potential Future Actions

Based on the documented absence (1990s – present) of the use or release of PFAS-containing 

materials at Edgemeade Mountain Home Training Site, no AOIs were identified during the PA. 

Evidence does not indicate that current or former ARNG activities contributed PFAS 

contamination to soil, groundwater, surface water, or sediment at the facility or adjacent areas. 

Edgemeade Mountain Home Training Center will not move forward in the CERCLA process.
CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

MS

PD

6/19/2019

6/19/2019

NOTES Preliminary Assessment for PFAS at Edgemead Mtn HTS, ID

1:6,000

6/19/2019 ­ Figure 7-1 PM RG 6/19/2019

12420 Milestone Center Drive

Germantown, MD 20876

Summary of Findings

Base Map: Source: Esri, DigitalGlobe, GeoEye,

Earthstar Geographics, CNES/Airbus DS, USDA, USGS,

Q:\Projects\ENV\GEARS\GEO\ARNG PFAS\900-CAD-GIS\920-GIS or Graphics\MXD\ID\Edgemead_Mtn_HTS_Figures\Edgemead_Mtn_HTS_PA_Figures\Fig_7-1_Edgemead_Mtn_HTS_Summary.mxd

Legend

No Suspected Release

Facility Boundary

River/Stream

0 250 500 1,000

Feet

16
PFAS Preliminary Assessment Report

Edgemeade Mountain Home Training Site 

Mountain Home, ID

17

8. References

Idaho Department of Environmental Quality (IDEQ). 2019. Snake River (Middle) – Succor Creek 

Subbasin. Available at http://www.deq.idaho.gov/water-quality/surface-water/tmdls/table-ofsbas-tmdls/snake-river-middle-succor-creek-subbasin/?_sm_au_=iVVvjN2JMS4QHn0w

(Accessed March 2019).

Idaho Department of Water Resources (IDWR). 2019. Available at https://dataidwr.opendata.arcgis.com/pages/popular-maps (Accessed March 2019).

Idaho Division of Environmental Quality (IDEQ) Southwest Idaho Regional Office. 1996. An 

Evaluation of Bacteria in Ground Water Near Mountain Home, Elmore County, Idaho. March.

Idaho Geological Survey (IGS). 2019. https://www.idahogeology.org/webmap. Accessed 21 

March 2019.

National Oceanic and Atmospheric Administration. National Centers for Environmental 

Information Data. Available at https://www.ncdc.noaa.gov/cdo-web/datatools/normals. 

Accessed May 2019. 

North Wind, Inc (North Wind). 2010. Final Environmental Assessment for Construction and 

Operation of the Edgemeade Readiness Center Facility and the Tactical Unmanned Aerial 

System Storage and Maintenance Facility Idaho Army National Guard Elmore County, Idaho. 

July. 

USGS. 1996. Summary of the Snake River Plain Regional Aquifer-System Analysis in Idaho and 

Eastern Oregon. July. 

U.S. Environmental Protection Agency (USEPA). September 1991. Guidance for Performing 

Preliminary Assessments Under CERCLA.

Wood & Clemens. 2002. Geologic and Tectonic History of the Western Snake River Plain, Idaho 

and Oregon
PFAS Preliminary Assessment Report

Edgemeade Mountain Home Training Site 

Mountain Home, ID

Appendix A 

Data Resources
PFAS Preliminary Assessment Report

Edgemeade Mountain Home Training Site

Mountain Home, ID

Data Resources will be provided separately on CD. Data Resources for the Edgemeade 

Mountain Home Training Site include:

Prior Environmental Reports

• 1996 An Evaluation of Bacteria in Ground Water Near Mountain Home, Elmore County, 

Idaho

• 2010 Final Environmental Assessment for Construction and Operation of the Edgemeade 

Readiness Center Facility and the Tactical Unmanned Aerial System Storage and 

Maintenance Facility, Idaho Army National Guard, Elmore County, Idaho

• 2013 Integrated Cultural Resources Management Plan for Sites and Training Installations of 

the Idaho Army National Guard, Fiscal Years 2013-2017

Edgemeade Mountain Home Training Site EDR Report

• 2019 Edgemeade Mountain Home Training Site EDR Report

• 1990 Edgemeade Land License for National Guard Purposes
PFAS Preliminary Assessment Report

Edgemeade Mountain Home Training Site 

Mountain Home, ID

 

Appendix B 

Preliminary Assessment Documentation
PFAS Preliminary Assessment Report

Edgemeade Mountain Home Training Site 

Mountain Home, ID

 

Appendix B.1 

Interview Records




PFAS Preliminary Assessment Report

Edgemeade Mountain Home Training Site 

Mountain Home, ID

 

Appendix B.2 

Visual Site Inspection Checklists








PFAS Preliminary Assessment Report

Edgemeade Mountain Home Training Site 

Mountain Home, ID

 

Appendix B.3 

Conceptual Site Model Information
Preliminary Assessment – Conceptual Site Model Information 

Site Name: Edgemeade Mountain Home Training Site

Why has this location been identified as a site?

“Hangar” building on-site. (During PA it was discovered that this is not a true hangar. No aircraft.)

Are there any other activities nearby that could also impact this location?

No

Training Events

Have any training events with AFFF occurred at this site? No

If so, how often? N/A

How much material was used? Is it documented? N/A

Identify Potential Pathways: Do we have enough information to fully understand over land surface 

water flow, groundwater flow, and geological formations on and around the facility? Any direct 

pathways to larger water bodies?

Surface Water:

Surface water flow direction? N/A. Ephemeral drainage only.

Average rainfall? 9.98 inches

Any flooding during rainy season? No

Direct or indirect pathway to ditches? High rate of inflitration

Direct or indirect pathway to larger bodies of water? No

Does surface water pond any place on site? No

Any impoundment areas or retention ponds? Rainwater collection tanks for landscaping. Not used.

Any NPDES location points near the site? Mtn Home Air Force Base. 12 miles to the SW.

How does surface water drain on and around the flight line? N/A
Preliminary Assessment – Conceptual Site Model Information 

Groundwater:

Groundwater flow direction? South to southwest

Depth to groundwater? Varies. 10 ft bgs – 400 ft bgs.

Uses (agricultural, drinking water, irrigation)? Nearby Mtn Home has wells for municipal potable 

purposes.

Any groundwater treatment systems? No

Any groundwater monitoring well locations near the site? No

Is groundwater used for drinking water? Not on-site.

Are there drinking water supply wells on installation? GIS shows one, however, site personnel report 

potable water comes from a municipal source.

Do they serve off-post populations? N/A

Are there off-post drinking water wells downgradient ? Yes, 1 + miles away.

Waste Water Treatment Plant:

Has the installation ever had a WWTP, past or present? No

If so, do we understand the process and which water is/was treated at the plant? N/A

Do we understand the fate of sludge waste? N/A

Is surface water from potential contaminated sites treated? N/A

Equipment Rinse Water

1. Is firefighting equipment washed? Where does the rinse water go?

No

2. Are nozzles tested? How often are nozzles tested? Where are nozzles tested? Are nozzles cleaned after 

use? Where does the rinse water flow after cleaning nozzles?

N/A

3. Other?
Preliminary Assessment – Conceptual Site Model Information 

Identify Potential Receptors: 

Site Worker N/A (no AFFF releases or PFAS sources)

Construction Worker N/A

Recreational User N/A

Residential N/A

Child N/A

Ecological N/A

Note what is located near by the site (e.g. daycare, schools, hospitals, churches, agricultural, livestock)?

Schools and residences nearby.

Documentation 

Ask for Engineering drawings (if applicable).

Has there been a reconstruction or changes to the drainage system? When did that occur?
PFAS Preliminary Assessment Report

Edgemeade Mountain Home Training Site 

Mountain Home, ID

 

Appendix C 

Photographic Log
PreliminaryAssessment Report

AECOM

Edgemeade Mountain Home Training Site

Perfluorooctane-Sulfonic Acid (PFOS) and 

Perfluorooctanoic Acid (PFOA) Impacted Sites 

ARNG Installations, Nationwide

APPENDIX C – Photographic Log

Army National Guard, Preliminary 

Assessment for PFAS

Edgemeade Mountain Home Training 

Site Mountain Home, Idaho

Description:

Armory Building ABC fire 

extinguisher 

(February 25, 2019)

Photograph No. 1

Description:

Armory Building water fire 

suppression system

(February 25, 2019)

Photograph No. 2
AECOM

Preliminary Assessment Report

Edgemeade Mountain Home Training Site

Perfluorooctane-Sulfonic Acid (PFOS) and 

Perfluorooctanoic Acid (PFOA) Impacted Sites ARNG 

Installations, Nationwide

APPENDIX C – Photographic Log

Army National Guard, Preliminary 

Assessment for PFAS

Edgemeade Mountain Home Training 

Site Mountain Home, Idaho

Description:

Fire suppression water 

sprinklers 

(February 25, 2019)

Photograph No. 3