FINAL

Preliminary Assessment Report

Mather AASF, California

Perfluorooctane-Sulfonic Acid (PFOS) and Perfluorooctanoic 

Acid (PFOA) Impacted Sites

ARNG Installations, Nationwide

February 2020

Prepared for:

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
PFAS Preliminary Assessment Report

Mather AASF, California

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Table of Contents

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

1. Introduction..........................................................................................................................6

1.1 Authority and Purpose................................................................................................6

1.2 Preliminary Assessment Methods ..............................................................................6

1.3 Report Organization ...................................................................................................7

1.4 Facility Location and Description................................................................................7

1.5 Facility Environmental Setting ....................................................................................8

Soil...................................................................................................................8

Geology ...........................................................................................................8

Hydrogeology ..................................................................................................8

Hydrology ........................................................................................................9

Climate ............................................................................................................9

Current and Future Land Use........................................................................10

2. Fire Training Areas.............................................................................................................14

2.1 Wash Rack ...............................................................................................................14

3. Non-Fire Training Areas.....................................................................................................16

3.1 Airfields.....................................................................................................................16

3.2 ASE Storage Building...............................................................................................16

3.3 C-12 Hangar.............................................................................................................16

3.4 Storage Shed ...........................................................................................................17

4. Emergency Response Areas .............................................................................................19

5. Adjacent Sources...............................................................................................................20

5.1 UCMR3 Data ............................................................................................................20

5.2 Former Mather Air Force Base .................................................................................20

5.3 Private Aviation Companies at Sacramento Mather Airport......................................21

5.4 Fire Training Area .....................................................................................................21

5.5 California Department of Forestry and Fire Protection.............................................21

5.6 Mather ARFF ............................................................................................................21

5.7 Emery Worldwide Flight 17 Crash............................................................................22

5.8 Air Force B-52 Bomber Crash ..................................................................................22

6. Preliminary Conceptual Site Model....................................................................................24

6.1 AOI 1: Wash Rack ....................................................................................................24

6.2 AOI 2: Airfields..........................................................................................................25

7. Conclusions .......................................................................................................................28

7.1 Findings....................................................................................................................28

7.2 Uncertainties ............................................................................................................28

7.3 Potential Future Actions ...........................................................................................29

References..................................................................................................................................33
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Mather AASF, California

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Tables

Table ES-1 AOIs at Mather AASF

Table 7-1 AOIs at Mather AASF

Table 7-2 Uncertainties

Table 7-3 PA Findings Summary

Figures

Figure ES-1 Summary of Findings

Figure ES-2 Summary of Findings – Adjacent Sources

Figure ES-3 Preliminary Conceptual Site Model, Mather AASF, CA

Figure 1-1 Mather AASF Facility Location

Figure 1-2 Groundwater Features

Figure 1-3 Surface Water Features

Figure 2-1 Fire Training Areas

Figure 3-1 Non-Fire Training Areas

Figure 5-1 Adjacent Sources

Figure 6-1 Areas of Interest

Figure 6-2 Preliminary Conceptual Site Model, Mather AASF, CA

Figure 7-1 Summary of Findings

Figure 7-2 Summary of Findings – Adjacent Sources

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
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Acronyms and Abbreviations

AASF Army Aviation Support Facility

AECOM AECOM Technical Services, Inc.

AFB Air Force Base

AFFF aqueous film forming foam

Amec Foster Wheeler Amec Foster Wheeler Environment & Infrastructure, Inc.

amsl above mean sea level

AOI area of interest

ARFF Aircraft Rescue and Firefighting

ARNG Army National Guard 

ASE Aviation Support Equipment

bgs below ground surface

BRAC Base Realignment and Closure Commission

CAARNG California Army National Guard

CAL FIRE California Department of Forestry and Fire

CERCLA Comprehensive Environmental Response, Compensation, and Liability 

Act

CSM conceptual site model

EDR Environmental Data Resources, Inc.

°F degrees Fahrenheit 

ft feet

ft/ft feet per feet

FTA fire training area

MGD million gallons per day

PA Preliminary Assessment

PFAS per- and poly-fluoroalkyl substances

PFOA perfluorooctanoic acid

PFOS perfluorooctanesulfonic acid

ppt parts per trillion

SDS safety data sheet

SI Site Inspection

UCMR3 Third Unregulated Contaminant Monitoring Rule

US United States

USACE United States Army Corps of Engineers

USEPA United States Environmental Protection Agency

VSI visual site inspection
PFAS Preliminary Assessment Report

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Executive Summary

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

Army National Guard (ARNG)-Installations & Environment Division, 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 the potential exposure to 

humans and the effect on the environment 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. 

AECOM completed a PA for PFAS at the Mather Army Aviation Support Facility (AASF; also 

referred to as the “facility”) in Mather, California, to assess potential PFAS release areas and 

exposure pathways to receptors. The current AASF is constructed on a parcel of land formerly 

part of Mather Air Force Base. Occupation of the property by California ARNG (CAARNG) began 

in 1985, and the licensing term was amended in 1994 to extend indefinitely. The performance of 

this PA included the following tasks: 

• Reviewed available administrative record documents and Environmental Data Resources,

Inc. (EDR) report packages to obtain information relevant to potential PFAS releases

• Conducted a 1-day site visit on 4 March 2019

• Interviewed current Mather AASF personnel during the site visit including the CAARNG

Instructor Pilot, Commander, and Sergeant; and Mather Aircraft Rescue and Firefighting

(ARFF) Firefighters

• Completed visual site inspections (VSIs) at known or suspected PFAS release locations and

documented with photographs

• Identified Areas of Interest (AOIs) and developed a preliminary conceptual site model (CSM)

to summarize potential source-pathway-receptor linkages of potential PFAS in soil,

groundwater, surface water, and sediment for each AOI

Two AOIs related to potential PFAS releases were identified at Mather AASF during the PA. The 

AOIs are shown on Figure ES-1 and in Table ES-1 below:

Table ES-1: AOIs at Mather AASF

Area of Interest Name Used by Release Dates

AOI 1 Wash Rack CAARNG Approximately 

2010

AOI 2 Airfields CAARNG

Potentially as 

early as 1998 until 

approximately 

2003

Based on information obtained during the PA, there is potential for exposure to PFAS 

contamination in media at or near the facility. PFAS sources adjacent to the AASF are shown on 

Figure ES-2, and the preliminary CSM for Mather AASF, which presents the potential receptors 

and media impacted, is shown on Figure ES-3. Based on the US Environmental Protection 

Agency (USEPA) third Unregulated Contaminant Monitoring Rule data, it was indicated that PFAS 
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were detected in a public water system above the USEPA lifetime Health Advisories within 5 miles 

of the facility. 
Southwest Airfield

Wash Rack

Center Airfield

Northeast Airfield

ASE Storage

C-12 Hangar

Storage Shed

AOI 2

AOI 1

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12420 Milestone Center Drive

Germantown, MD 20876

Summwary of Findings

Base Map: Source: Esri, DigitalGlobe, GeoEye,

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

0 175 350 700

Feet

1:4,200 ­ Area of Interest

Potential PFAS Area

No Suspected Release

Facility Boundary

Water Body

3
EVA Flight

Training Academy

Mather Aviation,LLC

Mather Jet Center

/Duncan Aviation, Inc.

Air Force B-52

Bomber Crash

Mather ARFF

ARNG and Air

Force FTA #2

ARNG and Air

Force FTA #3

ARNG and

Air Force

FTA #1 Emery Worldwide

Flight 17 Crash

Fire

Training

Area

CAL FIRE

Mather AFB

Main Runway

Mather AFB

Former Sewage

Treatment Plant

Mather AFB

Former Gravel Pit

Mather AFB

Building 17775

(Fire Station)

Mather AFB

Morrison Creek

Mather AFB

South Ditch

Mather AFB

West Ditch

Elite Air

Interiors

Morrison Creek

Fol s om South Canal

­ Figure ES-2

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DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community

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Summary of Findings - Adjacent Sources

12420 Milestone Center Drive

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Legend

Potential PFAS Area

No Suspected Release

Facility Boundary

Water Body

Wetland

River/Stream

Canal/Ditch

0 800 1,600 3,200

Feet

4
Media

SOURCE PATHWAY RECEPTOR

AOI 1

AOI 2

Potential AFFF 

release

PFAS in 

surface soil

Human 

activities

Precipitation/ 

run-off

Leaching/ 

infiltration

Airborne soil 

particulate

Surface soil 

at AOI

Surface 

water/ 

sediment

Subsurface 

soil

Shallow 

groundwater

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

Possible complete pathway

Complete pathway

/ / / /

Site 

Worker

Construction 

Worker Resident Recreational User

Site 

Worker

Construction 

Worker Resident

/ / / /

/ / / /

/ / / /

/ / / /

LEGEND

Figure ES-3

Preliminary Conceptual Site Model

Mather AASF, CA

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

Recreational User

Notes:

1. The resident and recreational user receptors 

refer to an off-site resident and recreational user.

2. Current risk practice suggests the exposure 

pathway for dermal contact is insignificant 

compared to ingestion, but supporting data is 

sparse and continues to be studied. 

5
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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, 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 W912DR-12-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 poly-fluoroalkyl substances 

(PFAS) (a suite of related chemicals), primarily releases of aqueous film forming foam (AFFF) 

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 these PFAS 

compounds in the environment will vary. 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. On 

13 July 2018, under the authority of the Deputy Director of the Division of Drinking Water, 

California issued drinking water notification levels of 14 parts per trillion (ppt) for PFOA and 13 

ppt for PFOS. Notification levels are non-regulatory health-based advisory levels established for 

contaminants in drinking water for which maximum contaminant levels have not been established. 

This report presents findings of a PA for PFAS at California ARNG (CAARNG) Mather Army 

Aviation Support Facility (AASF; also referred to as the “facility”) in Mather, CA, 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 Part 300), and USACE requirements and guidance. 

This PA documents the known fire training areas (FTAs) as well as additional locations where 

PFAS may have been released to the environment at Mather AASF. The term PFAS will be used 

throughout this report to encompass all PFAS chemicals being evaluated, including PFOS and 

PFOA, which are key components AFFF.

1.2 Preliminary Assessment Methods

The performance of this PA included the following tasks:

• Reviewed available administrative record documents and Environmental Data Resources, 

Inc. (EDR) report packages to obtain information relevant to potential PFAS releases

• Conducted a 1-day site visit on 4 March 2019

• Interviewed current Mather AASF personnel during the site visit including the CAARNG

Instructor Pilot, Commander, and Sergeant; and, Mather Aircraft Rescue and Firefighting 

(ARFF) Firefighters

• Completed visual site inspections (VSIs) at known or suspected PFAS release locations and 

documented with photographs 
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• Identified Areas of Interest (AOIs) and developed a preliminary conceptual site model (CSM) 

to summarize potential source-pathway-receptor linkages of potential PFAS in soil, 

groundwater, surface water, and sediment for each AOI

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 potential PFAS releases 

at the facility identified during the site visit. 

• Section 4 – Emergency Response Areas: describes areas of potential PFAS release at the 

facility, specifically in response to emergency situations. 

• Section 5 – Adjacent Sources: describes sources of potential 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

Mather AASF is an operational maintenance shop for CAARNG aircraft located at 10616 

Superfortress Avenue, Mather, CA 95655. The facility is in Mather Field, which was the former 

flightline operations area of Mather Air Force Base (AFB) and was granted for use and occupation 

by CAARNG under a 25-year land license beginning on 1 November 1985. Mather AFB was 

designated for realignment under the Base Realignment and Closure Commission (BRAC) in 

1988 and closure was received in 1993 (Amec Foster Wheeler Environment & Infrastructure, Inc. 

[Amec Foster Wheeler], 2015). Following closure, the AASF was officially transferred from the 

Department of the Air Force to the Department of the Army with the disclaimer that the Department 

of the Air Force would be responsible for the remediation of any environmental contamination 

caused by and resulting from Air Force activities. In 1994, the license for Mather AASF was 

amended to extend the licensing term indefinitely. Leasing records are included in Appendix A. 

The facility borders the Sacramento Mather Airport to the northeast and is situated in the 

Sacramento metropolitan area and Sacramento Valley (Figure 1-1). The facility is about 11 miles 

east of Sacramento. 
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1.5 Facility Environmental Setting

Mather AASF occupies 31 acres of land, approximately 97% of which is composed of impervious 

surfaces (HazCon, 2017). The areas surrounding Mather AASF are primarily the cargo and 

general aviation facilities at the Sacramento Mather Airport. Other surrounding areas include the 

Mather Regional Park, Mather Commerce Center, a Veteran Affairs hospital complex, day care 

and elementary schools, churches, and residential communities to the north and south (Amec 

Foster Wheeler, 2015). The facility sits at an elevation of 92 feet (ft) above mean seal level (amsl),

with a slight general topographic gradient to the west/southwest. There are no significant natural 

topographic features surrounding the facility. 

Soil

The soils at Mather AASF generally consist of gravelly loam and loam with well-developed, 

moderately to strongly weathered, and low erosion potential characteristics. Varying amounts of 

clay and gravel also exist in the soils. The clay content increases with depth and coarse gravel 

may be encountered at depths greater than 20 ft below ground surface (bgs) (Amec Foster 

Wheeler, 2015). The soils are primarily derived from American River valley and stream terrace 

deposits (US Department of Agriculture, 1954).

Geology

Mather AASF is located within the Great Valley geomorphic province, an alluvial plain located 

between the uplands of the Coast Ranges and the Sierra Nevada provinces (California Geological 

Survey, 2002). At the facility, Pleistocene-aged terrace sand, gravel, and cobbles overlie the 

deeper Pliocene-aged Laguna Formation, which unconformably overlies the Early Pliocene

Mehrten Formation (Amec Foster Wheeler, 2016; Marchand and Allwardt, 1981; Figure 1-2).

The uppermost geologic units at Mather AASF comprise three alluvial terrace deposits, which, 

from youngest to oldest, include the Riverbank, undifferentiated alluvial gravel, and Arroyo Seco 

formations (Shlemon et al., 2000). These deposits occur within nested fluvial-fill terraces and 

ancient and active river channels and are each characterized by sand, gravel, and cobbles within 

silt and clay matrices of varying thickness and lateral extent. The Arroyo Seco Formation truncates 

the underlying Laguna Formation, which is a westward thickening alluvial wedge of interbedded 

clay and silt, sand, and gravel within a sandy to silty matrix (Marchand and Allwardt, 1981). The 

Laguna Formation directly overlies and is coeval to the Mehrten Formation, which comprises two 

interbedded units of gray to black sand and blue to brown clay, silt, and sand with some gravel. 

In the vicinity of Mather AASF, the Laguna Formation ranges from 200 to 400 ft thick, and the 

Mehrten Formation ranges from 200 to 500 ft thick (Amec Foster Wheeler, 2016). 

Hydrogeology

The following hydrogeologic units have been identified through previous investigations at Mather 

AFB (Amec Foster Wheeler, 2016):

• Unit Ap (upper unit of the Laguna Formation)

• Unit A (upper unit of the Laguna Formation)

• Unit Bu (middle unit of Laguna Formation)

• Unit B (middle unit of the Laguna Formation)

• Unit C (lower unit of the Laguna Formation)

• Unit D (lower unit of the Laguna Formation)
PFAS Preliminary Assessment Report

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• Mehrten Formation

Unit Ap contains a perched water-bearing zone, and Unit B generally has the highest potential for 

contaminant migration due to a high transmissivity. Units A through C are transected by the water 

table going from east to west (Amec Foster Wheeler, 2016). Two primary aquifers exist within the 

unconsolidated deposits of the Laguna and Mehrten Formations. The majority of potable wells 

are screened within the Mehrten Formation, which is the primary source of drinking water for the 

surrounding area (Amec Foster Wheeler, 2015). 

Regional groundwater flow is generally in the southwest direction but may be influenced by 

groundwater pumping in the city of Elk Grove. Localized groundwater is also generally in the 

southwest direction, with an average hydraulic gradient of 0.002 feet per feet (ft/ft) (Amec Foster 

Wheeler, 2015). However, a large potentiometric depression has formed along the northwestern 

installation boundary of former Mather AFB due to remedial pumping in extraction wells; therefore, 

local groundwater variations are expected (URS Group, Inc., 2014). Depth to groundwater is 

measured at approximately 40 ft bgs for the perched aquifer and 90 ft bgs for the deeper aquifer 

(Amec Foster Wheeler, 2015). Groundwater features are presented on Figure 1-2. 

Mather AASF is located in the Sacramento County Water Agency’s Zone 40 North Service Area, 

which receives potable water from the existing water distribution system at former Mather AFB.

The Mather AFB water distribution system was conveyed in 1998 via an easement to the 

Sacramento County. Currently, the water distribution system includes two groundwater wells and 

a six million gallon per day (MGD) water treatment plant located at the Independence of Mather 

residential development (USACE, 2012). However, potable water was additionally derived from 

wells located in the weapons storage area/K-9 compound prior to Mather AFB closure and from 

four main base wells prior to 1997 (Amec Foster Wheeler, 2015). 

Hydrology

A drainage ditch is located near the northeastern portion of the AASF and drains to the Folsom 

South Canal. The Folsom South Canal flows southerly, supplying agricultural lands to the south.

Storm water in the northeastern airfield and refueling pads is drained in the northeast direction,

towards the drainage ditch. All other storm water is diverted to storm drain inlets on and around 

the AASF that connect to the drainage system of Mather Field (HazCon, 2017). There are no 

identified wetlands within the AASF property, but several seasonal wetlands exist in undeveloped 

portions of Mather Field due to the presence of an underlying impermeable soil layer of clay or 

hardpan (Amec Foster Wheeler, 2015). 

Surface water runoff generally follows the slope of the American River valley and drains westsouthwest. Mather AASF is primarily in the Lake Greenhaven-Sacramento River Watershed, but

the southwestern portion of the facility is in the Upper Morrison Creek Watershed. Morrison Creek 

is located approximately 1.5 miles to the southeast and is a tributary of Sacramento River, located 

approximately 12 miles west of Mather AASF. Surface water in the drainage system of Mather 

Field is also captured in various drainage ditches such as the West Ditch and South Ditch. Surface 

water features are presented on Figure 1-3.

Climate

Mather AASF is in a semi-arid, Mediterranean climate zone. The winter “rainy season” extends 

from November to February, and the summer “dry season” extends from June to August. The 

average annual rainfall is approximately 20 inches. Summer temperatures peak in July, with an 

average high of 94 degrees Fahrenheit (°F) and an average low of 61 °F. Winter temperatures 

are lowest in December with, an average high of 55 °F and an average low of 40 °F. Prevailing 

wind speeds are southerly year-round due to the orientation of the Sacramento Valley and 
PFAS Preliminary Assessment Report

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influence of the Sierra Nevada Mountains. Snowfall is extremely rare, but frost occasionally 

occurs (Cline, Neigher, and Bellinder; 2010). 

Current and Future Land Use

Mather AASF serves as a CAARNG aviation maintenance and storage facility for rotary and fixed 

wing aircraft. Mather AASF is comprised of a hangar, maintenance and storage areas, operations 

and administrative buildings, and related infrastructure including parking lots, aircraft parking 

areas, wash rack, and refueling pads. The AASF is categorized as a small-quantity hazardous 

waste generator, because it manages a variety of hazardous materials. Reasonably anticipated 

future land use is not expected to change from the current land use described above.
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Facility Location

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Groundwater Features

Base Map: Source: Esri, DigitalGlobe, GeoEye,

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

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Legend

Inferred Groundwater Flow

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Figure 1-3

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12420 Milestone Center Drive

Germantown, MD 20876

Surface Water Features

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

1:62,500 ­

Legend

Facility Boundary

Water Body

Wetland

River/Stream

Canal/Ditch

Pipeline

Surface Water Flow Direction

0 0.5 1 2

Miles

13
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2. Fire Training Areas

One former FTA was identified through record reviews during the PA. A description and the 

location of the FTA are shown on Figure 2-1. PA interview and VSI documents are included in 

Appendix B, and photographs are included in Appendix C.

2.1 Wash Rack

The wash rack was identified as an FTA during an interview with the CAARNG Staff Sergeant. 

The Staff Sergeant stated that there was a single fire training event conducted at the wash rack 

in approximately 2010. The fire training event involved the discharge of Tri-MaxTM fire 

extinguishers, reportedly filled with Ansul SILV-EX Class A Foam (non-AFFF). However, some 

uncertainty about the contents of the Tri-MaxTM fire extinguishers used in the training was 

introduced after the VSI found evidence of AFFF storage at the facility (see Section 3.4 for more 

details). Therefore, the exact contents and amount of discharge from the Tri-MaxTM fire 

extinguishers are unknown. Any foam that was discharged during the training was left in place to 

evaporate or disperse with the wind. 

The wash rack is located at geographic coordinates 38°33’53.1”N; 121°17’39.1”W. The drains in 

the wash rack area lead to an oil water separator, which then flows into the sanitary sewer system. 

One Tri-MaxTM fire extinguisher was observed next to the wash rack drain during the VSI. The TriMaxTM extinguisher remains equipped with presumably either Class A foam or AFFF. The 

CAARNG Fire Safety Sergeant stated that the Tri-MaxTM extinguishers have not been 

hydrostatically tested or replaced during his tenure of six years at the facility. 
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12420 Milestone Center Drive

Germantown, MD 20876

Fire Training Area

Base Map: Source: Esri, DigitalGlobe, GeoEye,

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

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Legend

Potential PFAS Area

Facility Boundary

Water Body

­

0 200 400 800

Feet

15
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3. Non-Fire Training Areas

Four non-FTAs where AFFF was stored and/or potentially released were identified during the PA. 

A description of each non-FTA is presented below, and the non-FTAs are shown on Figure 3-1. 

3.1 Airfields 

Three separate airfields are located at the AASF: Northeast Airfield, Center Airfield, and 

Southwest Airfield. The geographic coordinates and designations of the three airfields are as 

follows:

• Northeast Airfield (38°33’57.7”N; 121°17’22.1”W)

• Center Airfield (38°33’53.0”N; 121°17’28.4”W)

• Southwest Airfield (38°33’49.6”N; 121°17’34.9”W)

Training sessions where personnel would familiarize themselves with discharging the Tri-MaxTM

fire extinguishers, also referred to as “familiarization training” were conducted in the three airfields. 

According to the CAARNG Instructor Pilot, a single training session would involve the discharge 

of approximately one Tri-MaxTM fire extinguisher. Familiarization training was conducted 

approximately annually and sometimes more often. The CAARNG Instructor Pilot had knowledge 

of the training occurring during the years 1998 to 2003. 

The contents of the Tri-MaxTM fire extinguishers (Class A foam or AFFF) used during familiarization 

training are unknown. Any foam that was discharged during the familiarization training was left in 

place to evaporate or disperse with the wind. 

Approximately six Tri-MaxTM fire extinguishers were observed on or in the vicinity of the airfield 

during the VSI. Most of the Tri-MaxTM extinguishers were stationed next to helipads on the airfield. 

The Tri-MaxTM extinguishers remain equipped with presumably either Class A foam or AFFF. The 

CAARNG Fire Safety Sergeant stated that the Tri-MaxTM extinguishers have not been 

hydrostatically tested or replaced during his tenure of six years at the facility. 

3.2 ASE Storage Building

The Aviation Support Equipment (ASE) Storage Building is an approximately 6,800 square ft

space located on the western installation boundary at geographic coordinates 38°33’50.4”N; 

121°17’39.5”W. The building is shared between the AASF and the National Guard unit stationed 

at the facility.

During the VSI, four Tri-MaxTM fire extinguishers were observed stored in the AASF side of the 

building. The Tri-MaxTM fire extinguishers were out of commission at the time and not indicated to 

have ever leaked or been used within the building. 

3.3 C-12 Hangar

The C-12 Hangar is an approximately 7,100 square ft building located at geographic coordinates 

38°33’52.4”N; 121°17’35.6”W. The C-12 Hangar is used for the support of Mather AASF 

operations.

The VSI did not find any evidence of AFFF in the hangar. Only ABC fire extinguishers were present 

within the hangar, and there was no fire suppression system. CAARNG personnel additionally 

confirmed that no AFFF fire suppression system has ever been present in the hangar. Two Tri-
PFAS Preliminary Assessment Report

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17

MaxTM fire extinguishers were observed outside the hangar adjacent to the Southwest Airfield. It 

is unknown if the fire extinguishers are currently in commission. 

3.4 Storage Shed

The Storage Shed is located adjacent to the C-12 Hangar at geographic coordinates 

38°33’53.0”N; 121°17’36.4”W. The storage shed is used for the storage of hazardous materials 

During the VSI, four FireAde 2000 3% AFFF and five Chemguard 3% AFFF 5-gallon containers 

were found stored in the shed. The interviewed CAARNG personnel were not aware of this AFFF 

storage and could not recall how the AFFF was obtained. It was hypothesized that the AFFF may 

have come from the CAARNG Roseville Armory, since Mather AASF conducts maintenance for 

the armory. The CAARNG Staff Sergeant initially recalled only using Ansul SILV-EX Class A Foam 

for fire training but could not state with certainty that AFFF was never used within the AASF after 

the discovery of the AFFF storage. The CAARNG personnel maintained records of the 

Chemguard 3% AFFF safety data sheet (SDS) within the facility, which is attached in Appendix 

A. 
Southwest Airfield

Center Airfield

Northeast Airfield

ASE Storage

C-12 Hangar

Storage Shed

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12420 Milestone Center Drive

Germantown, MD 20876

Non-Fire Training Areas

Base Map: Source: Esri, DigitalGlobe, GeoEye,

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0 175 350 700

Feet

1:4,200 ­ Legend

Potential PFAS

No Suspected Release

Facility Boundary

Water Body

18
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4. Emergency Response Areas

Emergency responses to crashes sometimes require flame suppression, which may result in the 

release of PFAS to the environment in the form of AFFF. No emergency response areas were 

identified within the current Mather AASF facility during the PA through interviews with AASF 

personnel, whose knowledge covers the period of 1988 to present day, or EDR reports. Aircraft 

emergency services are provided by the Mather ARFF, and all other emergency services are 

provided by the Sacramento Metro Fire Department.
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5. Adjacent Sources

Numerous potential off-facility sources of PFAS adjacent to the Mather AASF, not under the 

control of the CAARNG, were identified during the PA. A description of each adjacent source is 

presented below, and the adjacent sources are shown on Figure 5-1.

5.1 UCMR3 Data

Numerous off-facility drinking water wells have been identified in the vicinity of the AASF. A few of 

the drinking water wells are operated by the California American Water Company and provide 

water to the surrounding businesses west and north of the former Mather AFB through a direct 

water distribution line (Amec Foster Wheeler, 2015). The Nut Plains Drive well from the California 

American Water Company - Suburban supply system was identified in the third Unregulated 

Contaminant Monitoring Rule (UCMR3) data to exceed the Health Advisories for PFAS. The 

UCMR3 data is included in Appendix A. The Nut Plains Drive well is located within 5 miles of the 

AASF in the inferred cross-gradient hydrogeologic pathway and is screened from 240 to 428 ft 

bgs (CA Water Boards, 2019). Two drinking water wells (Juvenile Hall 1 and 2) are operated by 

the Sacramento County to supply water to a building complex on Branch Center Drive and are 

connected to a granular activated carbon treatment system. The remaining water wells are 

privately-owned and are used either for potable or industrial purposes such as mining. One 

privately-owned well (OFB-43), located approximately 3 miles southwest of the AASF, was 

identified as being used for irrigation purposes (Amec Foster Wheeler, 2015). Well locations are 

shown on Figure 1-2.

The Bethany Slavic Missionary Church has a PFAS-impacted drinking water well on its property. 

The impacted well is located approximately 1-3 miles downgradient (southwest) from the former 

Mather AFB and Mather AASF. The maximum detected concentration in the well was 59 parts per 

trillion (ppt), which is below the Health Advisories of 70 ppt for PFOS/PFOA (Cloud et al., 2019). 

5.2 Former Mather Air Force Base

Former Mather AFB was located on an approximately 5,845-acre property. Mather AFB began 

operations in 1918 and was designated for realignment under BRAC in 1988. Closure was 

received in 1993 and the installation transitioned to civilian use (Amec Foster Wheeler, 2015).

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

locations at former Mather AFB. A 2015 PA report on PFAS identified ten potential PFAS release 

locations (Amec Foster Wheeler, 2015). A 2016 SI report for the former Mather AFB FTA site 

FT011P confirmed that PFOS concentrations in soil exceeded the Office of Superfund 

Remediation and Technology Innovation resident and direct contact soil criteria, and PFOS and 

PFOA concentrations in groundwater exceeded the Health Advisories (Amec Foster Wheeler, 

2016). The former Mather AFB PFAS investigation reports are included in Appendix A.

During an interview with a CAARNG Instructor Pilot, three additional FTAs were identified within 

the former Mather AFB installation boundary and near the Mather AASF (Figure 5-1). The FTAs

were combined ARNG and Air Force extraction type exercises that may have involved 

extinguishing live fire with either water or foam. The amount and type of foam (Class A or AFFF) 

discharged is unknown. The interviewed Instructor Pilot could not recall specific dates when fire 

training exercises took place but could recall the occurrence of fire training exercises as early as 

1988 until approximately 2000. The geographic coordinates and designations of the three FTAs

are as follows:

• ARNG & Air Force FTA #1 (38°33’51.7”N; 121°17’44.0”W)
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• ARNG & Air Force FTA #2 (38°33’43.9”N; 121°17’45.6”W)

• ARNG & Air Force FTA #3 (38°33’46.4”N; 121°17’28.6”W)

5.3 Private Aviation Companies at Sacramento Mather Airport

A number of private aviation companies are present at the Sacramento Mather Airport. With the 

exception of Elite Air Interiors, at none of the companies could the use or storage of AFFF be 

determined during the PA. These companies are listed below.

• The EVA Flight Training Academy is located at 3745 Whitehead Street, Mather, CA 95655. 

The academy provides flight training to future airlines pilots and maintains a hangar.

• Mather Jet Center is a fixed-based operator located at 10510 Superfortress Avenue, Mather, 

CA 95655. Duncan Aviation, Inc. is an aircraft maintenance, repair, and overhaul company 

that is also located within the same facility.

• Mather Aviation, LLC is an aircraft maintenance company located at 10360 Macready 

Avenue, Mather, CA 95655. 

• Elite Air Interiors is located at 3868 Bazley Way, Hanger #7040, Mather, CA 95655. The 

company provides interior refurbishment services for aviation aircrafts. The company’s 

website advertises using “the highest quality, fire retardant, HR upholstery foams”. PFAS 

contamination from these industrial applications is unknown but possible (Elite Air Interiors, 

n.d.). The Elite Air Interiors hangar was previously a Mather AFB maintenance hangar 

(Building 7015) that stored AFFF and contained an AFFF fire suppression system. The 

Mather AFB maintenance hangar was identified as a potential PFAS release area in the 

former Mather AFB PA report (Amec Foster Wheeler, 2016).

5.4 Fire Training Area

During an interview with Mather AASF personnel, the area located northeast of the Sacramento 

Mather Airport was identified as an FTA. The FTA’s geographic coordinates are 38°34’08.5”N; 

121°15’47.6”W. The area is not within the boundary of the former Mather AFB and it is unclear 

who currently owns the property; however, a FedEx airplane is apparently parked in the area at 

all times. No further details such as AFFF usage or fire training activities are known about the 

FTA. 

5.5 California Department of Forestry and Fire Protection 

The California Department of Forestry and Fire Protection (CAL FIRE) maintains a hangar located

along Bazley Way and adjacent to Elite Air Interiors. It is unknown if AFFF is used or stored at the 

facility. The CAL FIRE hangar was previously a Mather AFB maintenance hangar (Building 7040) 

that stored AFFF and contained an AFFF fire suppression system. The Mather AFB maintenance 

hangar was identified as a potential PFAS release area in the former Mather AFB PA report (Amec 

Foster Wheeler, 2016).

5.6 Mather ARFF

Mather ARFF has a fire station on Sacramento Mather Airport property, located at geographic 

coordinates 38°33’33.1”N; 121°18’23.3”W. The ARFF provides emergency response to aircraft 

emergencies. According to an interview with two Mather ARFF firefighters, Mather ARFF has 

occupied the fire station since 2000, after the Emery Worldwide Flight 17 crash incident prompted 

the need for a municipal fire and emergency response unit at Sacramento Mather Airport. The 
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ARFF stores AFFF in their firetrucks, although they do not currently conduct fire training with AFFF 

at the station and are in the midst of transitioning out of AFFF usage. However, the ARFF 

firefighters indicated that they participated in a helicopter crash fire training exercise at the airport 

airfield in approximately 2011. The exact location and what the fire training exercise entailed, such 

as if AFFF was used, was not specified. 

The fire station was previously occupied by the Mather AFB firefighting unit, who stored their crash 

response trucks in the station. The fire station (Building 7075) was also identified as a potential 

PFAS release area in the former Mather AFB PA report (Amec Foster Wheeler, 2016).

5.7 Emery Worldwide Flight 17 Crash

On 16 February 2000, Emery Worldwide Airlines, Inc. (Emery Worldwide) Flight 17 crashed into 

an auto salvage yard, approximately 2.5 miles east of the Sacramento Mather Airport. The 

airplane was attempting to return to the airport after experiencing a loss of pitch control (National 

Transportation Safety Board, 2003). The auto salvage yard contained 573 cars, some of which 

were set ablaze by the crash and contained gasoline in their tanks. According to eyewitness 

accounts, jet fuel was spilled on the ground and “flames went up about 200 to 300 feet in the air” 

(Curiel et al., 2000). Due to the presence of a fuel fire, firefighting response with foam is likely,

although the type of foam (Class A or AFFF) and quantity used is unknown. 

5.8 Air Force B-52 Bomber Crash 

On December 1982, an Air Force B-52 bomber plane crashed into a cow pasture while practicing 

simulated combat takeoff exercises. The crash location was approximately one mile west of the 

Mather AFB runway and nearby a busy intersection (McKinley, 1982). Due to the historical usage 

of AFFF by former Mather AFB, it is possible that AFFF may have been used in the emergency 

response. 
EVA Flight

Training Academy

Mather Aviation,LLC

Mather Jet Center

/Duncan Aviation, Inc.

Air Force B-52

Bomber Crash

Mather ARFF

ARNG and Air

Force FTA #2

ARNG and Air

Force FTA #3

ARNG and

Air Force

FTA #1 Emery Worldwide

Flight 17 Crash

Fire

Training

Area

CAL FIRE

Mather AFB

Main Runway

Mather AFB

Former Sewage

Treatment Plant

Mather AFB

Former Gravel Pit

Mather AFB

Building 17775

(Fire Station)

Mather AFB

Morrison Creek

Mather AFB

South Ditch

Mather AFB

West Ditch

Elite Air

Interiors

Morrison Creek

Fol s om South Canal

­ Figure 5-1

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12420 Milestone Center Drive

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Legend

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Facility Boundary

Water Body

Wetland

River/Stream

Canal/Ditch

0 800 1,600 3,200

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23
PFAS Preliminary Assessment Report

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6. Preliminary Conceptual Site Model

Based on the PA findings, there was one area where fire training may have occurred and one 

area where AFFF may have been incidentally spilled to the ground surface. As such, these areas 

are determined to be AOIs and may be potential PFAS source areas. The AOIs and CSMs for 

these AOIs are shown on Figures 6-1 and 6-2 and summarized below.

Although the use of AFFF could not be confirmed, the following AOI was identified as a potential

PFAS source area:

• AOI 1 – Wash Rack

• AOI 2 – Airfields 

The following sections describe the CSM components and the specific CSM developed for the

AOI. The CSM identifies the three components necessary for a potentially complete exposure 

pathway: (1) source, (2) pathway, (3) receptor. If any of these elements are missing, the pathway 

is considered incomplete. 

In general, the potential PFAS exposure pathways 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 is sparse and 

continues to be the subject of PFAS toxicological studies (National Ground Water Association, 

2018). Receptors for Mather AASF include site workers, construction workers residents, and 

recreational users. The preliminary CSMs for each AOI indicate which specific receptors could 

potentially be exposed to PFAS.

6.1 AOI 1: Wash Rack

AOI 1 is the wash rack, where one instance of a fire training exercise occurred in approximately 

2010 and may have resulted in a potential AFFF release.

The drains in the wash rack area lead to an oil water separator and then flow into the sanitary 

sewer system. Therefore, potential discharges of AFFF in the wash rack would primarily release 

directly into the sanitary sewer system. The sanitary sewer system is serviced by the Sacramento 

Regional County Sanitation District and Sacramento Area Sewer District. Wastewater is conveyed 

to the Sacramento Regional Wastewater Treatment Plant, which provides secondary wastewater 

treatment, participates in biosolids recycling/ land disposal, and discharges approximately 150 

MGD into the Sacramento River, located about 14 miles southwest of the AASF (USACE, 2012). 

Exposure to receptors via the surface water/sediment pathway is unlikely due to secondary 

treatment of wastewater and indirect connection to the Sacramento River. However, any runoff 

not captured by the oil water separator could reach nearby surface drainages that lead into 

tributaries of the Sacramento River and consequently present a potential exposure pathway to 

off-facility residents and recreational users. There are unpaved soil areas adjacent to the 

northeastern and western boundaries of the wash rack, which may receive potential discharges 

of AFFF or runoff from affected ground surfaces. Therefore, the pathway for potential exposure to 

PFAS contamination via inhalation of dust particles, or ingestion of surface soil during construction 

or maintenance, is considered potentially complete at the AOI for site workers and construction 

workers. Ground-disturbing activities to subsurface soil could present another potentially 

complete exposure pathway to construction workers via ingestion or inhalation of subsurface soil. 

The inhalation of dust for off-facility residents and recreational users is possible, but likely 

insignificant.

Based on a southwestern groundwater flow direction, the AOI may be upgradient of multiple public 

water supply wells located south and west of the AASF. The Nut Plains Drive well is an off-facility 
PFAS Preliminary Assessment Report

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25

drinking water supply well that had confirmed PFAS impacts from UCMR3 data. The Nut Plains

Drive well may receive groundwater contributions from the AASF and adjacent sources; therefore, 

the exposure pathway for groundwater to the off-facility resident receptor is potentially complete. 

The facility drinking water supply wells are located approximately 2 miles south of the AASF and 

may receive potentially contaminated groundwater from the AASF and adjacent sources. 

Therefore, the exposure pathway for groundwater to the site worker is potentially complete. The 

preliminary CSM for AOI 1 is shown on Figure 6-2.

6.2 AOI 2: Airfields

AOI 2 is comprised of the three AASF airfields (Northeast Airfield, Center Airfield, and Southwest 

Airfield) where familiarization training exercises occurred approximately annually during the 

confirmed years of 1998 to 2003.

Although the three airfields within AOI 2 are made of impervious surfaces, PFAS in surface water 

may flow into adjacent unpaved surfaces and into surface soil. PFAS are water soluble and can 

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

releases to surface soil occurred, it is possible that PFAS migrated from surface soil at AOI 2 to 

groundwater and waters in the Sacramento River. In addition, precipitation infiltrating into the 

unpaved surrounding areas of the AOI may cause the migration of PFAS from surface soil to 

groundwater and surface water.

AOI 2 lies within the Lake Greenhaven-Sacramento River and Upper Morrison Creek Watersheds,

and surface water from the Center and Southwest Airfields are drained by tributaries to the 

Sacramento River. Residents and recreational users may be exposed to PFAS in surface water 

and sediment off-facility via ingestion of surface water and sediment in the Sacramento River and 

its tributaries. The Northeast Airfield drains via an off-facility drainage ditch and connects to 

Folsom South Canal, which is used for irrigation in farmlands and may potentially present another 

exposure pathway to PFAS to off-facility residents via ingestion of agricultural products. 

The pathways and receptors for AOI 2 are the same as described in Section 6.1. The preliminary 

CSM for AOI 2 is shown on Figure 6-2.
­ Figure 6-1

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Areas of Interest

12420 Milestone Center Drive

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Legend

Area_of_Interest

Potential PFAS Area

No Suspected Release

Facility Boundary

River/Stream

Canal/Ditch

Surface Water Flow

Direction

Inferred Groundwater

Flow Direction

!C( Municipal Well

!C(

!C(

!C(

!C(

!C(

!C(

!C(

EVA Flight

Training

Academy

Mather

Aviation,

LLC

Mather Jet

Center/ Duncan

Aviation, Inc.

OFB-32 (Nut Plains Drive)

Mather

ARFF

ARNG and Air

Force FTA #2

ARNG and

Air Force FTA #3 ASE

Storage

Southwest Airfield

ARNG and

Air Force

FTA #1

C-12

Hangar

Storage

Shed Wash

Rack

Center

Airfield

Northeast

Airfield

CAL FIRE

Mather AFB

Main Runway

Mather AFB

South Ditch

Mather AFB

West Ditch

Elite Air

Interiors

Lake

Greenhaven-Sacramento

River Watershed

Upper Morrison

Creek Watershed

AOI 2

AOI 1

0 500 1,000 2,000

Feet

!C(!C(

!C(

!C(

!C(

A!

!C(

!C(

!C(

!C(

!C(

!C(

!C(

A!

!C( !C( Air Force B-52

Bomber Crash Mather AFB

Former Sewage

Treatment Plant

Mather AFB

Former

Gravel Pit

Mather AFB

Building 17775

(Fire Station)

Mather AFB

Morrison

Creek

Mather

AFB South

Ditch

Mather

AFB West

Ditch Upper Morrison

Creek Watershed

Morri son

Creek

Mor ris on Creek

!C(

Lake

Greenhaven-Sacramento

River Watershed Upper Morrison

Creek Watershed

Emery Worldwide

Flight 17 Crash

Fire

Training

Area

1

1

3

2

2

3 0 1,600 3,200 6,400

Feet

0 800 1,600 3,200

Feet

0 5,000 10,000 20,000

Feet

26
Media

SOURCE PATHWAY RECEPTOR

AOI 1

AOI 2

Potential AFFF 

release

PFAS in 

surface soil

Human 

activities

Precipitation/ 

run-off

Leaching/ 

infiltration

Airborne soil 

particulate

Surface soil 

at AOI

Surface 

water/ 

sediment

Subsurface 

soil

Shallow 

groundwater

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

Possible complete pathway

Complete pathway

/ / / /

Site 

Worker

Construction 

Worker Resident Recreational User

Site 

Worker

Construction 

Worker Resident

/ / / /

/ / / /

/ / / /

/ / / /

LEGEND

Figure 6-2

Preliminary Conceptual Site Model

Mather AASF, CA

Potential 

Off-Facility 

Source Not 

under 

Control of 

ARNG

Recreational User

Notes:

1. The resident and recreational user receptors 

refer to an off-site resident and recreational user.

2. Current risk practice suggests the exposure 

pathway for dermal contact is insignificant 

compared to ingestion, but supporting data is 

sparse and continues to be studied. 

27
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7. Conclusions

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

storage of AFFF and other PFAS-related activities at Mather AASF. The PA findings are based on 

the information presented in Appendix A and Appendix B.

7.1 Findings

Two AOIs related to potential PFAS release were identified (Table 7-1) at CAARNG’s Mather 

AASF during the PA (Figures 7-1 and 7-2). 

Table 7-1: AOIs at Mather AASF

Area of Interest Name Used by Release Dates

AOI 1 Wash Rack CAARNG Approximately 

2010

AOI 2 Airfields CAARNG

Potentially as 

early as 1998 until 

approximately 

2003

Based on information obtained during the PA at these AOIs, there is potential for exposure to 

PFAS contamination in media at or near the facility. The preliminary CSM for the AASF, which 

presents the potential receptors and media impacted, is shown on Figures 6-2 and 6-3. Multiple 

drinking water wells are located downgradient from the facility and may be impacted by PFAS 

contamination. One cross-gradient well (Nut Plains Drive) had confirmed PFAS impacts to 

drinking water from UCMR3 data (see Appendix A). 

The ASE Storage Building, C-12 Hangar, and Storage Shed at Mather AASF were determined to 

have no suspected PFAS release to the environment. Tri-Max fire extinguishers potentially 

containing AFFF were observed stationed either inside or outside of the ASE Storage Building 

and C-12 Hangar. The Storage Shed also contained AFFF 5-gallon buckets; however, in all 

instances, AFFF was not indicated to have ever leaked or been used at each location.

Numerous potential off-facility sources of PFAS were considered in the local area surrounding 

Mather AASF through interviews or review of previous environmental investigations, including the 

former Mather AFB, where PFAS have already been investigated in a PA and SI. The majority of 

the adjacent sources are located in the inferred downgradient/ cross-gradient groundwater and 

surface water flow path. Two exceptions are the FTA and Emery Worldwide Flight 17 Crash site, 

which are both located east and potentially upgradient from Mather AASF. 

7.2 Uncertainties

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 were not typically kept by the facility or available during the PA on the use of PFAS in 

training, firefighting, or other non-traditional activities, or on its disposition. 

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

with personnel who had direct knowledge of PFAS use at the facility. Sometimes, the provided 

information was vague or conflicted with other sources. Gathered information has a degree of 

uncertainty due to the absence of written documentation, the limited number of personnel with 
PFAS Preliminary Assessment Report

Mather AASF, California

29

direct knowledge due to staffing changes, the time passed since PFAS was first used (1969 to 

present), and a reliance on personal recollection. Inaccuracies may arise in potential PFAS 

release locations, dates of release, volume of releases, and the concentration of AFFF used. 

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.

In order to minimize the level of uncertainty, readily available data regarding the use and storage 

of PFAS were reviewed, retired and current personnel were interviewed, multiple persons were 

interviewed for the same potential source area, and potential source areas were visually 

inspected.

The following Table 7-2 summarizes the uncertainties associated with the PA.

Table 7-2: Uncertainties within the PA

Area of Interest Source of Uncertainty

AOI 1: Wash Rack The exact contents and amount of discharge from the Tri-MaxTM 

fire extinguishers are unknown.

AOI 2: Airfields The contents of the Tri-MaxTM fire extinguishers (Class A foam 

or AFFF) used during familiarization training are unknown. The 

dates of the familiarization training (1998-2003) are also 

estimated according to the tenure of the CAARNG Instructor 

Pilot. 

General Despite maintaining SDS records for AFFF, no AASF personnel 

interviewed were familiar with the presence of the AFFF storage 

or could state with confidence whether the AFFF had been used 

within the facility. 

7.3 Potential Future Actions

Based on the documented absence (1988 to present) of the use or release of AFFF from the ASE 

Storage Building, C-12 Hangar, and Storage Shed, evidence does not indicate that current or 

former ARNG activities having contributed PFAS contamination to soil, groundwater, surface 

water, or sediment at these locations. The ASE Storage Building, C-12 Hangar, and Storage Shed

will not move forward in the CERCLA process.

Interviews and records (covering 1988 to present) indicate that current or former ARNG activities 

may have resulted in potential PFAS releases at the two AOIs identified during the PA. Based on 

the preliminary CSMs developed for the AOIs, there is potential for receptors to be exposed to 

PFAS contamination in soil, groundwater, surface water, and sediment at these AOIs. Table 7-3

summarizes the rationale used to determine if the AOI should be considered for further 

investigation under the CERCLA process and undergo an SI. 
PFAS Preliminary Assessment Report

Mather AASF, California

30

Table 7-3: PA Findings Summary

Area of Interest AOI Location Rationale Potential 

Future Action

AOI 1: Wash Rack 38°33’53.1”N; 

121°17’39.1”W

Confirmed location of fire training 

exercise by interviewee with 

direct knowledge

Proceed to an 

SI, focus on 

soil, 

groundwater, 

surface water, 

sediment

AOI 2: Airfields 38°33’53.0”N; 

121°17’28.4”W

Confirmed location of 

familiarization exercises by 

interviewee with direct 

knowledge

Proceed to an 

SI, focus on 

soil, 

groundwater, 

surface water, 

sediment

ARNG will evaluate the need for an SI at Mather AASF based on the potential receptors, the 

potential migration of PFAS contamination off the facility, and the availability of resources.
Southwest Airfield

Wash Rack

Center Airfield

Northeast Airfield

ASE Storage

C-12 Hangar

Storage Shed

AOI 2

AOI 1

CLIENT

REVISED

SCALE

ARNG

GIS BY

CHK BY

GC

MS

11/6/2019

11/6/2019

NOTES Preliminary Assessment for PFAS at Mather AASF, CA

11/6/2019

Figure 7-1 PM RG 11/6/2019

Q:\Projects\ENV\GEARS\GEO\ARNG PFAS\900-CAD-GIS\920-GIS or Graphics\MXD\CA\Mather_AASF\Fig_7-1_Mather_AASF_Summary.mxd

12420 Milestone Center Drive

Germantown, MD 20876

Summwary of Findings

Base Map: Source: Esri, DigitalGlobe, GeoEye,

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

0 175 350 700

Feet

1:4,200 ­ Area of Interest

Potential PFAS Area

No Suspected Release

Facility Boundary

Water Body

31
EVA Flight

Training Academy

Mather Aviation,LLC

Mather Jet Center

/Duncan Aviation, Inc.

Air Force B-52

Bomber Crash

Mather ARFF

ARNG and Air

Force FTA #2

ARNG and Air

Force FTA #3

ARNG and

Air Force

FTA #1 Emery Worldwide

Flight 17 Crash

Fire

Training

Area

CAL FIRE

Mather AFB

Main Runway

Mather AFB

Former Sewage

Treatment Plant

Mather AFB

Former Gravel Pit

Mather AFB

Building 17775

(Fire Station)

Mather AFB

Morrison Creek

Mather AFB

South Ditch

Mather AFB

West Ditch

Elite Air

Interiors

Morrison Creek

Fol s om South Canal

­ Figure 7-2

CLIENT

REVISED

SCALE

PROJECT

ARNG

Preliminary Assessment for PFAS at Mather AASF, CA

11/6/2019

11/6/2019

11/6/2019

GC

ST

RG

GIS BY

CHK BY

PM

Base Map: Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus

DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community

11/6/2019

1:19,200

Q:\Projects\ENV\GEARS\GEO\ARNG PFAS\900-CAD-GIS\920-GIS or Graphics\MXD\CA\Mather_AASF\Fig_7-2_Mather_AASF_Summary_Adjacent.mxd

Summary of Findings - Adjacent Sources

12420 Milestone Center Drive

Germantown, MD 20876

Legend

Potential PFAS Area

No Suspected Release

Facility Boundary

Water Body

Wetland

River/Stream

Canal/Ditch

0 800 1,600 3,200

Feet

32
PFAS Preliminary Assessment Report

Mather AASF, California

33

References

Amec Foster Wheeler Environment & Infrastructure, Inc. (Amec Foster Wheeler). 2015. Final 

Perfluorinated Compounds Preliminary Assessment, Former Mather Air Force Base, 

California. December 2015. 

Amec Foster Wheeler. 2016. Final Perfluorinated Compounds (PFCs) Release Determination at 

Multiple BRAC Bases Site Investigation Report, Former Fire Training Area FT011P, Former 

Mather Air Force Base. November 2016.

CA Water Boards. 2019. Groundwater Ambient Monitoring and Assessment Program 

Groundwater Information System. 

California Geological Survey. 2002. California Geological Survey Note 36: California Geomorphic 

Provinces. California Department of Conservation. December 2002.

Cline, G., Neigher, A., and Bellinder, A., 2010. Climate of Sacramento, California. National 

Weather Service Office, Sacramento, California. August. 

Cloud, David S.; Phillips, Anna M.; Barboza, Tony. “Firefighting foam leaves toxic legacy in 

Californians’ drinking water.” Los Angeles Times. 8 October 2019. 

Curiel, Jonathan, et al. “Fiery Cargo Jet Crash Ignites Huge Fire / Crew of 3 killed as DC-8 feared 

hits auto yard near Sacramento.” SFGATE. 17 February 2000. 

Elite Air Interiors. n.d. Comprehensive Aircraft Interior Refurbishment Services. 

http://www.eliteairinteriors.com/ (Accessed May 2019).

GlobalSecurity.org. 2011. Mather Army Aviation Support Facility (AASF), Mather AFB, CA.

https://www.globalsecurity.org/military/facility/mather.htm (Accessed May 2019). 

Hazcon. 2017. Spill Prevention, Control, and Countermeasure Plan, Sacramento Army Aviation 

Support Facility, 10616 Superfortress Avenue, Mather, California 95655-1103. May 2017.

Marchand, D. E., and Allwardt, A. 1981. Late Cenozoic Stratigraphic Units, Northeastern San 

Joaquin Valley, California. United States Geological Survey. Bulletin 1470.

McKinley, Clark. “An Air Force B-52 bomber crashed after a simulated...” UPI Archives. 16 

December 1982. 

National Ground Water Association. 2018. Groundwater and PFAS: State of Knowledge and 

Practice. January 2018.

National Transportation Safety Board. 2003 Loss of Pitch Control on Takeoff, Emery Worldwide 

Airlines, Flight 17, McDonnell Douglas DC-8-71F, N8079U, Rancho Cordova, California, 

February 16, 2000. Aircraft Accident Report NTSB/AAR-03/02. Washington, D.C. 

Shlemon, R. J., Horner, T., Florsheim, J. 2000. Quaternary Geology of the Sacramento Area: 

Guidebook for Field Trip. Association of Engineering Geologists, Sacramento Section. March 

2000.

USEPA. 1991. Guidance for Performing Preliminary Assessments under CERCLA. EPA/540/G91/013. September 1991. 

URS Group, Inc. 2014. Annual and Fourth Quarter 2013 Mather Groundwater Monitoring Report, 

Former Mather Air Force Base (AFB). April. AR301403. 
PFAS Preliminary Assessment Report

Mather AASF, California

34

USACE. 2012. Draft Environmental Impact Statement, Mather Specific Plan Project, Sacramento 

County, California, ID: SPK-2002-561. June 2012. 

US Department of Agriculture. 1954. Soil Survey: Sacramento Area California. US Department 

of Agriculture, Washington, D.C.
PFAS Preliminary Assessment Report

Mather AASF, California

Appendix A

Data Resources
PFAS Preliminary Assessment Report

Mather AASF, CA

Data resources will be provided separately on CD. Data resources for Mather AASF include:

Environmental Data Resources, Inc. Geocheck Report

• 2019 Environmental Data Resources, Inc. Geocheck Report for Mather AASF, CA

CAARNG Leasing Information

• 2019 CA ARNG Leasing Documents E-mail from Tom White (CAARNG Real Estate 

Manager) to Stephanie Tjan (AECOM)

Mather Air Force Base PFAS Investigations

• 2015 Final Perfluorinated Compounds Preliminary Assessment, Former Mather Air Force 

Base, California 

• 2016 Final Perfluorinated Compounds Determination at Multiple BRAC Bases Site 

Investigation Report, Mather Air Force Base, Sacramento County, California

• 2016 Final Main Base/Strategic Air Command (SAC) Area (MBSA) Perfluorinated 

Compounds (PFC) Sampling Results, Former Mather Air Force Base, California 

Mather AASF License Documents

• 1986 Department of the Army License for National Guard Purposes, No. DACA05-3-86-505

• 1986 Mather AFB, CA; Department of the Air Force Permit No. DACA05-4-86-507

• 1994 Memorandum for the Secretary of the Army, the Secretary of the Air Force; Subject: 

Transfer of Parcel S, Consisting of Approximately 31 Acres of Land Improved with Five 

Buildings at Mather Air Force Base (AFB), CA to Department of the Army for use by the 

California National Guard 

• 1995 Memorandum for Adjutant General, State of Military Department; Subject: Mather Air 

Force Base, CA; License No. DACA05-3-86-505, Amendment No. 1

Mather AASF UCMR3 Data Set

• Tabulated UCMR3 Data Set

Miscellaneous Resources

• 1999 Mather Air Force Base Five-Year Review of Remedial Actions

• 2012 Draft Environmental Impact Statement, Mather Specific Plan Project, Sacramento 

County, California 

Spill Prevention, Control, and Countermeasure Plan

• 2017 Spill Prevention, Control, and Countermeasure Plan, Sacramento Army Aviation 

Support Facility, 10616 Superfortress Avenue, Mather, California 95655-1103
PFAS Preliminary Assessment Report

Mather AASF, California

Appendix B

Preliminary Assessment Documentation
PFAS Preliminary Assessment Report

Mather AASF, California

Appendix B.1

Interview Records
PA Interview Questionnaire - Environmental Manager Facility:_Mather AASF______

Interviewer:______ST________

Date/Time:______3/4/19______

Interviewee:_multiple (see below)_________

Title:__________________________________

Phone Number:_________________________

Email:_______________________________

Can your name/role be used in the PA Report? Y or N

Can you recommend anyone we can interview?

Y or N __________________________

1. Roles or activities with the Facility/years working at the Facility.

– Facility Commander, 5 years at facility

– Facility Instructor Pilot (Safety Officer)

– Staff Sergeant since 2001

– Sergeant Fire Safety Guy, 6 years at facility

2. Where can I find previous facility ownership information?

CAARNG has been tenant since 70s-80s, Air Force closed down and was BRACed in the 90s, Civilian

Airfield took over rest of the BRAC facility

3. What can you tell us about the history of PFAS including aqueous film forming foam (AFFF) at the

Facility? Was it used for any of the following activities, circle all that apply and indicate years of active

use, if known? Identify these locations on a facility map.

Maintenance said Tri-Maxes have not been hydrostatically tested or replaced, they

just do a checklist inspection; never refill or deplete

Fire Training Areas one training event conducted by at wash rack, occurred around

2010, wash rack leads to OWS

Firefighting (Active Fire)

Crash yes, responded to by Air Force or municipal FD depending on timeframe of crash

Fire Suppression Systems (Hangers/Dining Facilities) never had fire suppression systems

Fire Protection at Fueling Stations

Non-Technical/Recreational/ Pest Management

Metals Plating Facility

Waterproofing Uniforms (Laundry Facilities)

Other

4. Fill out CSM Information worksheet with the Environmental Manager.

5. Are any current buildings constructed with AFFF dispensing systems or fire suppression systems?

What are the AFFF/suppression system test requirements? What is the frequency of testing the

AFFF/suppression system? Do you have “As Built” drawings for the buildings?

No
PA Interview Questionnaire - Environmental Manager Facility:_Mather AASF______

Interviewer:______ST________

Date/Time:______3/4/19______

6. Are fire suppression systems currently charged with AFFF or have they been retrofitted for use of

high expansion foam? If retrofitted, when was thatdone?

No

7. How is AFFF procured? Do you have an inventory/procurement system that tracks use?

No inventory/procurement system, believes that Tri-Max always contained Class A

foam

8. What type of AFFF has been/is being used (3%, 6%, Mil Spec Mil-F-24385, High Expansion)?

Manufacturer (3M, Dupont, Ansul, National Foam, Angus, Chemguard, Buckeye, Fire Service Plus)?

Believed that Tri-Maxes contain Class A foam.

However, the VSI found evidence of four 5-gallon containers of FireAde 3% AFFF (manufactured

November 2011) and five 5-gallon containers of ChemGuard 3% AFFF. Staff was unaware of the

existence of this AFFF or how it got there. It was mentioned that the facility does maintenance for

Roseville Armory. recalls only putting in Sylvex Class A foam into Tri-Maxes.

9. Where is the AFFF stored? How is it stored (tanks, 55-gallon drums, 5-gallon buckets)? What

size are the storage tanks? Is the AFFF stored as a mixed solution (3% or 6%) or concentrated

material?

Stored in storage shed by C-12 hangar. See answer above.

10. How many FTAs are/were on this facility and where are they? Locate on a map. How many FTAs

are active and inactive? For inactive FTAs, when was the last time that fire training using AFFF

was conducted at them?

Only known FTA was the wash rack area.

Only one FTA mentioned as being off-facility. Has one FedEx plane parked in the area (need to follow

up with this).
PA Interview Questionnaire - Environmental Manager Facility:_Mather AASF______

Interviewer:______ST________

Date/Time:______3/4/19______

11. When a release of AFFF occurs during a fire training exercise, now and in the past, how is the

AFFF cleaned and disposed of? Were retention ponds built to store discharged AFFF? Was the

AFFF trickled to the sanitary sewer or left in the pond to infiltrate?

FTA training on wash rack disposed right into wash rack.

12. Can you recall specific times when city, county, and/or state personnel came on-post for training? If so,

please state which state/county agency or military entity? Do you have any records, including

photographs to share with us?

No

13. Did military routinely or occasionally fire train off-post? List the units that you can recall used/trained

at various areas.

No

14. Did individual units come with their own safety personnel, did they also bring their own AFFF? Was

training with AFFF part of these exercises? How were emergencies handled under these circumstances?

No

15. Are there specific emergency response incident reports (i.e., aircraft or vehicle

crash sites and fires)? If so, may we please copy these reports? Who (entity) was

the responder?

Not known
PA Interview Questionnaire - Environmental Manager Facility:_Mather AASF______

Interviewer:______ST________

Date/Time:______3/4/19______

16. Do you have records of fuel spill logs? Was it common practice to wash away fuel spills with

AFFF? Is/was AFFF used as a precaution in response to fuel releases or emergency runway

landings to prevent fires?

No

17. Was AFFF used for forest fires or fire management on-post/off-post? If so, please describe what

happened and who was involved?

No

18. Are there mutual aid/use agreements between county, city, and local fire department? Please list, even

if informal. If formalized, may we have a copy of the agreement?

N/A

19. Can you provide any other locations where AFFF has been stored, released, or used (i.e. hangars,

buildings, fire stations, firefighting equipment testing and maintenance areas, emergency response

sites, storm water/surface water, waste treatment plants, and AFFF ponds)?

Tri-Maxes are stored on airfield and around flightline

20. Are you aware of any other creative uses of AFFF? If so, how was AFFF used? What entities were

involved?

No
PA Interview Questionnaire - Environmental Manager Facility:_Mather AASF______

Interviewer:______ST________

Date/Time:______3/4/19______

21. Are there past studies you are aware of with environmental information on plants/animals/

groundwater/soil types, etc., such as Integrated Cultural Resources Management Plans or Integrated

Natural Resources Management Plans?

N/A

22. What other records might be helpful to us (environmental compliance, investigation records, admin

record) and where can we find them?

N/A

23. Do you have or did you have a chrome plating shop on base? What were/are the years of operation

of that chrome plating shop?

No

24. Do you know whether the shop has/had a foam blanket mist suppression system or used a fume

hood for emissions control? If foam blanket mist suppression was used, where was the foam

stored, mixed, applied, etc.?

No

25. How is off-spec AFFF disposed (used for training, turned in, or given to a local Fire Station)? If

applicable, do you know the name of the vendor that removes off-spec AFFF? Do you have copies of

the manifest or B/L?

There is no longer a surplus of Tri-Maxes. All Tri-Maxes that are on-site is everything that’s there. Expired

Tri-Max goes to Cal Fire of HAZMAT containment (basically they have an environment team that takes

care of disposal).
PA Interview Questionnaire - Environmental Manager Facility:_Mather AASF______

Interviewer:______ST________

Date/Time:______3/4/19______

26. Do you recommend anyone else we can interview? If so, do you have contact information for them?

– retiring state standardization officer/ former pilot
PA Interview Questionnaire – Fire Station Facility:__Mather AASF_____

Interviewer:____ST__________

Date/Time:______3/4/2019_______

Interviewee:_ ________________

Title:__Instructor Pilot___________________

Phone Number:_ __________

Email:_ _______

Can your name/role be used in the PA Report? Y or N

Can you recommend anyone we can interview?

Y or N __________________________

1. Roles or activities with the Facility/years working at the Facility.

Started in 1988-2003, then went over to aviation office. Part-time worker until 1991, and then became full

time.

Is currently a state standardization officer but will retire end of March 2019

2. What can you tell us about the history of AFFF at the Facility? Was it used for any of the following

activities, circle all that apply and indicate years of active use, if known? Identify these locations on a

facility map.

Maintenance (e.g., ramp washing)

Fire Training Areas

Firefighting (Active Fire)

Crash There was an incident in ~1991 on Runway 22 where an aircraft landing gear wouldn’t go

down so they completely foamed the runway, so the aircraft could do a hard landing/crash and

slide down runway

Fire Suppression Systems (Hangers/Dining Facilities)

Fire Protection at Fueling Stations

Non-Technical/Recreational/ Pest Management

3. Are any current buildings constructed with AFFF dispensing systems or fire suppression systems?

What are the AFFF/suppression system test requirements? What is the frequency of testing at the

AFFF/suppression systems?

No

4. Are fire suppression systems currently charged with AFFF or have they been retrofitted for use of

high expansion foam?

No
PA Interview Questionnaire – Fire Station Facility:__Mather AASF_____

Interviewer:____ST__________

Date/Time:______3/4/2019_______

5. How is AFFF procured? Do you have an inventory/procurement system that tracks use?

Not known

6. What type of AFFF has been/is being used (3%, 6%, Mil Spec Mil-F-24385, High Expansion)?

Manufacturer (3M, Dupont, Ansul, National Foam, Angus, Chemguard, Buckeye, Fire Service Plus)?

Not known

7. Is AFFF formulated on base? If so, where is the solution mixed, contained, transferred, etc.?

Not known

8. Where is the AFFF stored? How is it stored (tanks, 55-gallon drums, 5-gallon buckets)? What

size are the storage tanks? Is the AFFF stored as a mixed solution (3% or 6%) or concentrated

material?

Stored on the field in Tri-Maxes

9. How is the AFFF transferred to emergency response vehicles, suppression systems, flightline

extinguishers? Is/was there a specified area on the facility where vehicles are filled with AFFF and

does this area have secondary containment in case of spills? How and where are vehicles storing

AFFF cleaned/decontaminated?

Not known

10. Provide a list of vehicles that carried AFFF, now and in the past, and where are/were they located?

No fire truck as far back as 1988. The Air Force did have a fire truck that was parked at the former Air

Force Fire Dept (now Mather ARFF)
PA Interview Questionnaire – Fire Station Facility:__Mather AASF_____

Interviewer:____ST__________

Date/Time:______3/4/2019_______

11. Any vehicles have a history of leaking AFFF? Do you/did you test the vehicles spray patterns to

make sure equipment is working properly? How often are/were these spray tests performed and can

you provide the locations of these tests, now and in the past?

Not known

12. How many FTAs are/were on this facility and where are they? Locate on a map. How many FTAs

are active and inactive? For inactive FTAs, when was the last time that fire training using AFFF

was conducted at them?

The airfields are all FTAs where they would conduct familiarization training (1998-2003). They would

take turns with 10-40 men at spraying the Tri-Maxes until they would use up approximately one TriMax, so they could become familiar with how to use it.

There are 3 adjacent FTAs for extraction exercises conducted in conjunction with the AF and ARNG.

They would simulate an accident (unclear whether they used real or just pretended vehicle was on

fire). Have someone be a live dummy inside the helicopter or vehicle and they would simulate

extracting the unconscious person and detaching the battery and also putting out the fire with either

water or foam.

13. What types of fuels/flammables were used at the FTAs?

N/A

14. What was the frequency of AFFF use at each location? When a release of AFFF occurs during a fire

training exercise, now and in the past, how is/was the AFFF cleaned and disposed of? Were

retention ponds built to store discharged AFFF? Was the AFFF trickled to the sanitary sewer or

left in the pond to infiltrate?

Training at FTAs was conducted approximately annually and sometimes more. The 3 adjacent combined

army and AF FTAs were truck-mounted exercises.

Any foam that was sprayed would just be left on-site to evaporate, although they might have washed

down the helicopter have the exercises.

15. Are there mutual aid/use agreements between county, city, local fire department? Please list, even if

informal. If formalized, may we have a copy of the agreement? Can you recall specific times when city,

county, state personnel came on-post for training? If so, please state which state/county agency,

military entity? Do you have any records, including photographs to share with us?
PA Interview Questionnaire – Fire Station Facility:__Mather AASF_____

Interviewer:____ST__________

Date/Time:______3/4/2019_______

N/A

16. Did individual units come on-post with their own safety personnel, did they also bring their own AFFF?

Was training with AFFF part of these exercises? How were emergencies handled under these

circumstances?

N/A

17. Did military routinely or occasionally fire train off-post? List units that you can recall used/trained at

various areas.

N/A

18. Are there specific emergency response incident reports (i.e., aircraft or vehicle crash sites and fires)? If

so, may we please copy these reports? Who (entity) was the responder?

B52 crash off-base 4-5 miles in the early 90s. This was responded to by the municipal FD.

DHL crash in the auto salvage yard in the early 2000s. This was responded to by the AF FD.

19. Do you have records of fuel spill logs? Was it common practice to wash away fuel spills with

AFFF? Is/was AFFF used as a precaution in response to fuel releases or emergency runway

landings to prevent fires?

N/A

20. Was AFFF used for forest fires or fire management on-post/off-post? If so, please describe what

happened and who was involved?
PA Interview Questionnaire – Fire Station Facility:__Mather AASF_____

Interviewer:____ST__________

Date/Time:______3/4/2019_______

No

21. Can you provide any other locations where AFFF has been stored, released, or used (i.e. hangars,

buildings, fire stations, firefighting equipment testing and maintenance areas, emergency response

sites, storm water/surface water, waste water treatment plants, and AFFF ponds)?

Unknown

22. Are you aware of any other creative uses of AFFF? If so, how was AFFF used? What entities were

involved?

No

23. How is off-spec AFFF disposed (used for training, turned in, or given to a local Fire Station)? If

applicable, do you know the name of the vendor that removes off-spec AFFF? Do you have copies of

the manifest or B/L?

Unknown

24. Do you recommend anyone else we can interview? If so, do you have contact information for them?

– safety officer that then worked for Tri-Max, now he’s retired but he goes back to the 60s
PA Interview Questionnaire - Other Facility:_Mather ARFF______

Interviewer:___ST__________

Date/Time:___3/4/2019_______

Interviewee:__2 firefighters (anonymous)____

Title:__________________________________

Phone Number:_________________________

Email:_______________________________

Can your name/role be used in the PA Report? Y or N

Can you recommend anyone we can interview?

Y or N __________________________

Roles or activities with the Facility/Years working at the Facility:

One of the men has been at the facility when it was still part of the Air Force.

PFAS Use: Identify accidental/intentional release locations, time frame of release, frequency of releases,

storage container size (maintenance, fire training, firefighting, buildings with suppression systems (as

builts), fueling stations, crash sites, pest management, recreational, dining facilities, metals plating, or

waterproofing). How are materials ordered/purchased/disposed/shared with others?

The men recalled a few crashes: one was an airborne crash near Sunrise around Feb. 2000. Another was

the Emery Worldwide Flight 17 crash that happened in the auto salvage yard. The Emery crash was what

brought the municipal FD to move over to Mather ARFF site around 2000. Before, the AF occupied the site

but they shut base in 1994.

The AF crash trucks were stationed at the site.

FD is in the midst of transitioning out of the usage of AFFF, but the fire trucks still have AFFF. They also

use Halotron and Purple K.

ARFF conducts annual training on their own and at an off-site location such as in Dallas, TX. They used to

do a helicopter training crash at the airfield ~8 years ago.
PFAS Preliminary Assessment Report

Mather AASF, California

Appendix B.2

Visual Site Inspection Checklists
Visual Site Inspection Checklist

Names(s) of people performing VSI: S. Tjan, B. Packer, D. Calderon, B. Dahl

Recorded by: S. Tjan

ARNG Contact:

Date and Time: 3/4/2019

Method of visit (walking, driving, adjacent): walking

Source/Release Information

Site Name / Area Name / Unique ID: Mather AASF Airfield

16 acres

Historic Site Use (Brief Description): familiarization training

Current Site Use (Brief Description): Parking of helicopters, cargo loading and unloading

Physical barriers or access restrictions: fenced

1. Was PFAS used (or spilled) at the site/area? Y

1a. If yes, document how PFAS was used and usage time (e.g., fire fighting training 2001 to 2014):

airfields were the site of familiarization training with confirmed usage during 1998-2003

2. Has usage been documented? N

2a. If yes, keep a record (place electronic files on a disk):

3. What types of businesses are located near the site? Industrial / Commercial / Plating / Waterproofing / Residential

3a. Indicate what businesses are located near the site

4. Is this site located at an airport/flightline? Y

4a. If yes, provide a description of the airport/flightline tenants:

Mather Airport, FedEx hangar, UPS Mather Airport

Site / Area Acreage:

Sacramento Metropolitan Fire District Headquarters, Mather ARFF, DHL Express Service Point, UPS Mather

Airport

Page 1 of 12
Visual Survey Inspection Log

1. Does the facility have a fire suppression system? N

1a. If yes, indicate which type of AFFF has been used:

1b. If yes, describe maintenance schedule/leaks:

1c. If yes, how often is the AFFF replaced:

1d. If yes, does the facility have floor drains and where do they lead? Can we obtain an as built drawing?

Transport / Pathway Information

1. Does site/area drainage flow off installation? Y

1a. If so, note observation and location:

Yes, connects with drainage system of Mather Field or goes into Folsom South Canal

2. Is there channelized flow within the site/area? Y

2a. If so, please note observation and location:

Yes, northeast airfield connected to drainage ditch that leads to Folsom South Canal

3. Are monitoring or drinking water wells located near the site? Y

3a. If so, please note the location:

Multiple drinking water well to west and northwest

4. Are surface water intakes located near the site? N

4a. If so, please note the location:

5. Can wind dispersion information be obtained? N

5a. If so, please note and observe the location.

6. Does an adjacent non-ARNG PFAS source exist? Y

6a. If so, please note the source and location.

6b. Will off-site reconnaissance be conducted? N

Combined Air Force and ARNG training at helicopter pad and two other areas, Runway 22 was site of hard

landing, 2 airplane crashes, multiple hangars

Other Significant Site Features:

Migration Potential:

Page 2 of 12
Visual Survey Inspection Log

1. Has the infrastructure changed at the site/area? N

1a. If so, please describe change (ex. Structures no longer exist):

2. Is the site/area vegetated? Y

2a. If not vegetated, briefly describe the site/area composition:

3. Does the site or area exhibit evidence of erosion? N

3a. If yes, describe the location and extent of the erosion: 

4. Does the site/area exhibit any areas of ponding or standing water? N

4a. If yes, describe the location and extent of the ponding: 

Receptor Information

1. Is access to the site restricted? Y

1a. If so, please note to what extent:

fenced

2. Who can access the site?

2a. Circle all that apply, note any not covered above:

3. Are residential areas located near the site? Y

3a. If so, please note the location/distance:

residential areas ~1 mile to north and Independence at Mather community ~1.5 miles to south

4. Are any schools/day care centers located near the site? Y

4a. If so, please note the location/distance/type:

George Washington Carver School of Arts & Science ~1.3 miles to west

5. Are any wetlands located near the site? Y

5a. If so, please note the location/distance/type:

some vernal wetlands in Mather Field and also Mather Lake

Significant Topographical Features:

Site Workers / Construction Workers / Trespassers / Residential / Recreational

Users / Ecological

very few patches of dirt/gravel and an occasional tree

Page 3 of 12
Visual Survey Inspection Log

Additional Notes

Photographic Log

Photo ID/Name Date & Location Photograph Description

 The northernmost airfield is not used very often since three years ago.

Page 4 of 12
Visual Survey Inspection Log

Names(s) of people performing VSI: S. Tjan, B. Packer, D. Calderon, B. Dahl

Recorded by: S. Tjan

ARNG Contact:

Date and Time: 3/4/2019

Method of visit (walking, driving, adjacent): walking

Source/Release Information

Site Name / Area Name / Unique ID: ASE Storage Building, C-12 Hangar, Storage Shed

Historic Site Use (Brief Description): storage and hangar for aviation purposes

Current Site Use (Brief Description): same as above

Physical barriers or access restrictions: fenced

1. Was PFAS used (or spilled) at the site/area? N

1a. If yes, document how PFAS was used and usage time (e.g., fire fighting training 2001 to 2014):

2. Has usage been documented? N

2a. If yes, keep a record (place electronic files on a disk):

3. What types of businesses are located near the site? Industrial / Commercial / Plating / Waterproofing / Residential

3a. Indicate what businesses are located near the site

4. Is this site located at an airport/flightline? Y

4a. If yes, provide a description of the airport/flightline tenants:

Mather Airport, FedEx hangar, UPS Mather Airport

Tri-Max fire extinguishers were stored inside the ASE Storage building and outside the C-12 Hangar, AFFF 5-

gallon buckets were found inside the storage shed

Site / Area Acreage:

Sacramento Metropolitan Fire District Headquarters, Mather ARFF, DHL Express Service Point, UPS Mather

Airport

Page 5 of 12
Visual Survey Inspection Log

1. Does the facility have a fire suppression system? N

1a. If yes, indicate which type of AFFF has been used:

1b. If yes, describe maintenance schedule/leaks:

1c. If yes, how often is the AFFF replaced:

1d. If yes, does the facility have floor drains and where do they lead? Can we obtain an as built drawing?

Transport / Pathway Information

1. Does site/area drainage flow off installation? Y

1a. If so, note observation and location:

Yes, connects with drainage system of Mather Field or goes into Folsom South Canal

2. Is there channelized flow within the site/area? Y

2a. If so, please note observation and location:

Yes, northeast airfield connected to drainage ditch that leads to Folsom South Canal

3. Are monitoring or drinking water wells located near the site? Y

3a. If so, please note the location:

Multiple drinking water well to west and northwest

4. Are surface water intakes located near the site? N

4a. If so, please note the location:

5. Can wind dispersion information be obtained? N

5a. If so, please note and observe the location.

6. Does an adjacent non-ARNG PFAS source exist? Y

6a. If so, please note the source and location.

6b. Will off-site reconnaissance be conducted? N

Other Significant Site Features:

Migration Potential:

Combined Air Force and ARNG training at helicopter pad and two other areas, Runway 22 was site of hard

landing, 2 airplane crashes, multiple hangars

Page 6 of 12
Visual Survey Inspection Log

1. Has the infrastructure changed at the site/area? N

1a. If so, please describe change (ex. Structures no longer exist):

2. Is the site/area vegetated? Y

2a. If not vegetated, briefly describe the site/area composition:

3. Does the site or area exhibit evidence of erosion? N

3a. If yes, describe the location and extent of the erosion: 

4. Does the site/area exhibit any areas of ponding or standing water? N

4a. If yes, describe the location and extent of the ponding: 

Receptor Information

1. Is access to the site restricted? Y

1a. If so, please note to what extent:

fenced

2. Who can access the site?

2a. Circle all that apply, note any not covered above:

3. Are residential areas located near the site? Y

3a. If so, please note the location/distance:

residential areas ~1 mile to north and Independence at Mather community ~1.5 miles to south

4. Are any schools/day care centers located near the site? Y

4a. If so, please note the location/distance/type:

George Washington Carver School of Arts & Science ~1.3 miles to west

5. Are any wetlands located near the site? Y

5a. If so, please note the location/distance/type:

some vernal wetlands in Mather Field and also Mather Lake

very few patches of dirt/gravel and an occasional tree

Site Workers / Construction Workers / Trespassers / Residential / Recreational

Users / Ecological

Significant Topographical Features:

Page 7 of 12
Visual Survey Inspection Log

Additional Notes

Photographic Log

Photo ID/Name

Tri-Maxes are stored in ASE Storage which is comprised of two parts - one is for the National Guard Unit and the other is for the

facility. AFFF was found stored in 5-gallon containers in the storage shed by the C-12 Hangar. The wash rack leads to an oil water

separator.

Date & Location Photograph Description

Page 8 of 12
Visual Survey Inspection Log

Names(s) of people performing VSI: S. Tjan, B. Packer, D. Calderon, B. Dahl

Recorded by: S. Tjan

ARNG Contact:

Date and Time: 3/4/2019

Method of visit (walking, driving, adjacent): walking

Source/Release Information

Site Name / Area Name / Unique ID: Wash rack

0.26 acres

Historic Site Use (Brief Description): Used for the washing of aircraft vehicles

Current Site Use (Brief Description): same as above

Physical barriers or access restrictions: fenced

1. Was PFAS used (or spilled) at the site/area? N

1a. If yes, document how PFAS was used and usage time (e.g., fire fighting training 2001 to 2014):

2. Has usage been documented? N

2a. If yes, keep a record (place electronic files on a disk):

3. What types of businesses are located near the site? Industrial / Commercial / Plating / Waterproofing / Residential

3a. Indicate what businesses are located near the site

4. Is this site located at an airport/flightline? Y

4a. If yes, provide a description of the airport/flightline tenants:

Mather Airport, FedEx hangar, UPS Mather Airport

Site / Area Acreage:

one reported instance of fire training activities on wash rack in ~2010

Sacramento Metropolitan Fire District Headquarters, Mather ARFF, DHL Express Service Point, UPS

Mather Airport

Page 9 of 12
Visual Survey Inspection Log

1. Does the facility have a fire suppression system? N

1a. If yes, indicate which type of AFFF has been used:

1b. If yes, describe maintenance schedule/leaks:

1c. If yes, how often is the AFFF replaced:

1d. If yes, does the facility have floor drains and where do they lead? Can we obtain an as built drawing?

Transport / Pathway Information

1. Does site/area drainage flow off installation? Y

1a. If so, note observation and location:

Yes, connects with drainage system of Mather Field or goes into Folsom South Canal

2. Is there channelized flow within the site/area? Y

2a. If so, please note observation and location:

Yes, northeast airfield connected to drainage ditch that leads to Folsom South Canal

3. Are monitoring or drinking water wells located near the site? Y

3a. If so, please note the location:

Multiple drinking water well to west and northwest

4. Are surface water intakes located near the site? N

4a. If so, please note the location:

5. Can wind dispersion information be obtained? N

5a. If so, please note and observe the location.

6. Does an adjacent non-ARNG PFAS source exist? Y

6a. If so, please note the source and location.

6b. Will off-site reconnaissance be conducted? N

Other Significant Site Features:

Migration Potential:

Combined Air Force and ARNG training at helicopter pad and two other areas, Runway 22 was site of hard

landing, 2 airplane crashes, multiple hangars

Page 10 of 12
Visual Survey Inspection Log

1. Has the infrastructure changed at the site/area? N

1a. If so, please describe change (ex. Structures no longer exist):

2. Is the site/area vegetated? Y

2a. If not vegetated, briefly describe the site/area composition:

3. Does the site or area exhibit evidence of erosion? N

3a. If yes, describe the location and extent of the erosion: 

4. Does the site/area exhibit any areas of ponding or standing water? N

4a. If yes, describe the location and extent of the ponding: 

Receptor Information

1. Is access to the site restricted? Y

1a. If so, please note to what extent:

fenced

2. Who can access the site?

2a. Circle all that apply, note any not covered above:

3. Are residential areas located near the site? Y

3a. If so, please note the location/distance:

residential areas ~1 mile to north and Independence at Mather community ~1.5 miles to south

4. Are any schools/day care centers located near the site? Y

4a. If so, please note the location/distance/type:

George Washington Carver School of Arts & Science ~1.3 miles to west

5. Are any wetlands located near the site? Y

5a. If so, please note the location/distance/type:

some vernal wetlands in Mather Field and also Mather Lake

Significant Topographical Features:

very few patches of dirt/gravel and an occasional tree

Site Workers / Construction Workers / Trespassers / Residential / Recreational

Users / Ecological

Page 11 of 12
Visual Survey Inspection Log

Additional Notes

Photographic Log

Photo ID/Name

The wash rack leads to an oil water separator.

Date & Location Photograph Description

Page 12 of 12
PFAS Preliminary Assessment Report

Mather AASF, California

Appendix B.3

Conceptual Site Model Information
Preliminary Assessment – Conceptual Site Model Information

Site Name: Mather AASF

Why has this location been identified as a site?

Facility contains an AASF and multiple aviation repair functions on multiple buildings at the facility.

There is a confirmed release area. AFFF is currently stored or used at the facility.

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

Location of former Mather Air Force Base, located near Sacramento Mather Airport

Training Events

Have any training events with AFFF occurred at this site? Potentially with AFFF at wash rack and

airfields

If so, how often? One event at wash rack in ~2010, approximately annually at airfields from 1998-2003

How much material was used? Is it documented? Unknown

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? Generally southwest but also northeast towards Folsom South Canal

Average rainfall? 20 inches

Any flooding during rainy season? No

Direct or indirect pathway to ditches? Direct pathway to unnamed drainage ditch connecting to Folsom

South Canal

Direct or indirect pathway to larger bodies of water? Indirect to Morrison Creek and tributaries of

Sacramento River

Does surface water pond any place on site? No

Any impoundment areas or retention ponds? No

Any NPDES location points near the site? No

How does surface water drain on and around the flight line? Towards storm drains on center and

southwest airfields, towards unnamed drainage ditch for northeast airfield
Preliminary Assessment – Conceptual Site Model Information

Groundwater:

Groundwater flow direction? Generally southwest although variable due to local GW pumping

Depth to groundwater? 40 ft bgs for shallow aquifer and 90 ft bgs for deeper aquifer

Uses (agricultural, drinking water, irrigation)? Drinking water, irrigation, and agriculture

Any groundwater treatment systems? Some off-facility DW wells connected to GAC system

Any groundwater monitoring well locations near the site? Yes, at former Mather AFB

Is groundwater used for drinking water? Yes

Are there drinking water supply wells on installation? No, supply wells are at Independence of Mather

community

Do they serve off-post populations? Yes

Are there off-post drinking water wells downgradient? Yes, multiple

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?

Do we understand the fate of sludge waste?

Is surface water from potential contaminated sites treated?

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?

No

3. Other?
Preliminary Assessment – Conceptual Site Model Information

Identify Potential Receptors:

Site Worker – Yes

Construction Worker - Yes

Recreational User – Yes (potentially off-facility user of Sacramento River and its tributaries)

Residential - Yes (via off-facility drinking water)

Child - Yes

Ecological – Yes (eco receptors of Sacramento River and its tributaries)

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

Mather Airport, FedEx hangar, UPS Mather Airport

Documentation

Ask for Engineering drawings (if applicable).

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

None known
PFAS Preliminary Assessment Report

Mather AASF, California

Appendix C

Photographic Log
Appendix C - Photographic Log

Army National Guard, Preliminary

Assessment for PFAS

Mather AASF Mather, California

Preliminary Assessment Report

Mather AASF

Perfluorooctane-Sulfonic Acid (PFOS) and

Perfluorooctanoic Acid (PFOA) Impacted Sites

ARNG Installations, Nationwide

Photograph No. 1

Description:

Tri-Max 30 mobile fire

extinguisher shown next to

wash rack drain

Orientation:

Northwest

Date 3/4/2019

Time 10:09

Photograph No. 2

Description:

Wash rack drain leads to oil

water separator (shown),

which is drained by an

environmental contractor

Orientation:

North

Date 3/4/2019

Time 10:11

AECOM Page 1 of 3
Appendix C - Photographic Log

Army National Guard, Preliminary

Assessment for PFAS

Mather AASF Mather, California

Preliminary Assessment Report

Mather AASF

Perfluorooctane-Sulfonic Acid (PFOS) and

Perfluorooctanoic Acid (PFOA) Impacted Sites

ARNG Installations, Nationwide

Photograph No. 3

Description:

A dry chemical fire

extinguisher (non-AFFF)

observed in the C-12 Hangar

Orientation:

North

Date

Time

Photograph No. 4

Description:

Three Tri-Max 30 mobile fire

extinguishers observed in the

ASE Storage building

Orientation:

West

Date 3/4/2019

Time 10:25

AECOM Page 2 of 3
Appendix C - Photographic Log

Army National Guard, Preliminary

Assessment for PFAS

Mather AASF Mather, California

Preliminary Assessment Report

Mather AASF

Perfluorooctane-Sulfonic Acid (PFOS) and

Perfluorooctanoic Acid (PFOA) Impacted Sites

ARNG Installations, Nationwide

Photograph No. 5

Description:

Multiple 5-gallon buckets of

3% AFFF (brands FireAde

2000 and Chemguard) found

in storage shed adjacent to the

C-12 Hangar

Orientation:

Southwest

Date 3/4/2019

Time 10:38

Photograph No. 6

Description:

Facility safety data sheet

records showing 3% AFFF

products in the storage shed.

However, the safety data

sheet was only obtained for

the 3% AFFF ("Chemguard C303").

Orientation:

East

Date 3/4/2019

Time 10:32

AECOM Page 3 of 3