United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
EPA/ROD/R10-93/053
February 1993
Superfund
Record of Decision:
Fairchild Air Force Base 4
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4.
50272-101
REPORTDOCUMENTA110N 1'. REPORTNO. .
PAGE EPA/ROD/RIO-93/053
Title 8nd Subtitle
SUPERFUND RECORD OF DECISION
Fairchild Air Force Base 4 Areas (Operable Unit 1), WA
First Remedial Action - Final
Aulhor(.)
2
3. Recipient'. Ace_Ion No.
s
A8port Date
02/11/93
&
7.
&
Performing Organization A8pt. No.
8.
Performing Organization "'1118 .nd Add,..
10
Project TuJcJWortt Unit No.
11. Contract(C) or Grant(G) No.
(C)
(G)
12. Sponsoring Orglnlzatlon "'1118 Ind Add.....
U.S. Environmental Protection
401 M Street, S.W.
Washington, D.C. 20460
13. Type of Report' Period Cov8r8d
Agency
800/800
14.
15. Supplementlry Not..
PB94-964604
16. Ab8tract (Umlt: 200 words)
The Fairchild Air Force Base 4 Areas (Operable Unit 1) site is located approximately 12
miles west of Spokane, Washington. Land use in the area is predominantly agricultural.
An estimated 135 people reside in a trailer park located within 1,500 feet of the site.
The upper and lower aquifers in the immediate vicinity and downgradient from the site
are used for municipal and residential water supplies. The inactive Craig Road -
Landfill (CRL) occupies approximately 100 acres of the Base and contains three inactive
disposal areas. These areas previously were used to dispose of various types of
wastes, including miscellaneous sanitary and industrial waste, construction and
demolition debris, coal ash from power plants, solvents, dry cleaning filters. paints,
thinners, and possibly electrical transformers. The northeast landfill was active from
the late 1950s to early 1960s and the southwest landfill was active from the late 1960s
to the late 1970s. As part of the U.S. Air Force Installation Restoration Program
(IRP), onsite environmental investigations of past disposal practices were initiated.
Sampling indicated that offsite residential wells, located directly northeast of the
CRL, were contaminated with TCE above drinking water standards. The Air Force
immediately connected these residences to an alternate water supply. In 1991, the Air
Force initiated a removal action at the site and began pumping water from the upper
(See Attached Page)
17. Document Analysis I. D88c:rlptors
Record of Decision - Fairchild Air Force Base 4 Areas (Operable Unit 1), WA
First Remedial Action - Final
Contaminated Media: soil, debris, gw
Key Contaminants: VOCs (benzene, TCE)
b.
Id8ntlfl8l'81'Open-Ended T8I'1II8
c.
COSAT1 FleldIGroup
18. AVIllabilhy Statlmlnt
18. Security Clua (Thl. Report)
None
2D. Security au. (This P_ge)
None
21. No.ofPlge.
68
22. Price
(See ANSI-Z38.1S)
S. ImrtlUCtion. on R8118rN
OPT1ONAL FORM 272 (4-77)
(Formerly NTIS-35)
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EPA/ROD/RI0-93/053
Fairchild Air Force Base 4 Areas (Operable Unit 1), WA
First Remedial Action - Final
Abstract (Continued)
aquifer to remove contaminants and to minimize migration. Additionally, an air stripping
treatment system was constructed onsite to treat the extracted ground water. Construction.
of a pipeline to divert wastewater from the Base wastewater treatment plant (WWTP) is
underway currently, and will eliminate the discharge of the Base's WWTP effluent to the
infiltration pond and trenches on the landfill property. This ROD addresses the source
areas associated with subsurface disposal at the CRL, as well as onsite and offsite ground
water, as OUI. Future RODs will address the remaining contamination at the Base. The
primary contaminants of concern affecting the soil, debris, and ground water are VOCs,
including benzene and TCE.
The selected remedial action for this site includes capping the northeast and southwest
disposal areas at the landfill; performing a treatability study, then installing a soil
vapor extraction system on the capped area; extracting and treating the contaminated
ground water from the vapor aquifer onsite using air stripping, with offsite reinjection
or discharge downgradient of the site; controlling air emissions using granular activated
carbon, and disposing of any spent carbon offsite; inspecting, monitoring, reconstructing,
and/or abandoning offsite supply wells, as necessary; providing point of use and/or an
alternate water supply in the future, if needed; monitoring onsite and offsite ground
water; and implementing institutional controls, including deed restrictions, and site
access restrictions, including fencing. The estimated present worth cost for this
remedial action is $8,722,073, which includes an annual O&M cost ranging from $46,000 to
$393,000 for 30 years.
PERFORMANCE STANDARDS OR GOALS:
Remedial Action Objectives (RAO's) for the CRL are based on CERCLA requirements, the State.
of Washington's Model Toxics Control Act (MTCA) Method S, and overall reduction of the
cumulative excess cancer risk at the site to less than 10-5. The chemical-specific ground
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U'nited States Air Force
',~
Environmental Restoration Program
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Record of Decision
Craig Road Landiill (CRL)
Fairchild Air Force Base
,.
I
/
!
,
February 1993
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INSTALLATION RESTORATION PROGRAM (IRP) .
RECORD OF DECISION
CRAIG ROAD LANDFILL (CRL)
[Site ID No. LF-02 (SW8)]
FINAL
For
FAIRCHILD AIR FORCE BASE
Washington
FEBRUARY 1993
Prepared By
SCIENCE APPUCATIONS INTERNATIONAL CORPORATION
Environmental Remediation Division
14062 Denver West Parkway
Building 52, Suite 2SO
Golden, CO 80401
BASE PROJECT NO. GJKZ90-SOO1
USAF Contrad No. F3361S-8S-D-4S43, Task Order No. 07
ENVIRONMENTAL RESTORATION DIVISION
Richard J. Mestan, Captain
TlN'hniQl Project Manaaer
AIR FORCE CENTER FOR ENVIRONMENTAL EXCELLENCE
Environmental Services Ofrace
Environmental Restoration Division (AFCEFJESR)
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TABLE OF CONTENTS
Declaration of the Record of Decision
i;'~
~
Decision Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
I. Site Location and Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
n. Site History and Enforcement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
lli. Highlights of Community Participation. . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
IV. Scope and Role of Response Action Within Site Strategy. . . . . . . . . . . . . . . . . 6
V. Summary of Site ChardCteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
VI. Summary of Site Risks ................................. '. . . 21
vn. Remedial Action Objectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
VIn. Description of Alternatives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
IX. Summary of the Comparative Analysis of Alternatives. . . . . . . . . . . . . . . . . 48
X. The Selected Remedy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
XI. Statutory Determinations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Xll. Documentation of Significant Changes. . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Responsiveness Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
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DECLARA TION OF TIlE RECORD OF DECISION
SITE NAME AND LOCATION
Craig Road Landfill Operable Unit
Fairchild Air Force Base
Spokane County, Washington
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected remedial action for the Craig Road Landfill (CRL)
operable unit, Fairchild Air Force Base (AFB), Spokane, Washington, which was chosen in
accordance with the Comprehensive Environmental Response, Compensation, and Liability Act
of 1980 (CERCLA), as amended by the Superfund Amendments and Reauthorization Act of
1986 (SARA), and to the extent practicable, the National Oil and Hazardous Substances
Pollution Contingency Plan (NCP). This d~ision is based on the Administrative Record for this
site. . .
The lead agency for this decision is the U.S. Air Force. The U.S. Environmental Protection
Agency (EP A) approves of this decision and, along with the state of Washington Department of
Ecology (Ecology), has participated in the scoping of the site investigations and in the evaluation
of remedial investigation data. The state of Washington concurs with the selected remedy.
ASSESSMENT OF mE SITE
Actual or threatened releases of hazardous substances from this site, if not addressed by
implementing the response action selected in this Record of Decision (ROD), may present an
imminent and substantial endangerment to public health, welfare, or the environment.
DESCRIPrlON OF THE SELECTED REMEDY
The selected remedy for the CRL includes elements from two different categories of actions.
The first category is source controls, which are intended to minimize movement of contaminants
from the fill material in the landfill to the groundwater and to prevent direct exposure to
contaminated subsurface soil and debris. The second action category is groundwater controls.
These controls are intended to prevent further movement of contaminated groundwater across
the site boundary and to prevent consumption by area residents of groundwater exceeding
maximum contaminant levels (MCL). The combination of both source control and groundwater
control actions is n~ to achieve the broader objective of restoring contaminated
groundwater in the upper aquifer to levels that are safe for drinking.
The major components of the selected remedy include:
.
-------
.
~
.
q'~
'i
.
Installing an active soil vapor extraction/treatment system in both capped
areas
Extracting contaminated groundwater from the upper aquifer at the landfill
boundary and treating by air stripping and granular activated carbon;
treated groundwater will be disposed of at an off-site location
downgradient of the CRL property
Monitoring off-site water supply wells within the off-site portion of the
plume and providing point-of-use treatment andlor alternative water supply
if needed in the future
.
Monitoring groundwater in upper and lower aquifers
.
Implementing institutional controls.
STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the environment, complies with fed~ral
and state requirements that are legally applicable or relevant and appropriate to the remedial
action, and is cost effective. This remedy utilizes permanent solu~ons and alternative treatment
technologies to the maximum extent practicable for this site, and satisfies the stabJtory preference
for remedies that employ treatment that reduces toxicity, mobility, or volume as a principal
element.
Because this remedy will result in hazardous substances remaining on site above health-based
levels, a review will be conducted within 5 years after commencement of remedial action to
ensure that the remedy continues to provide adequate protection of human health and the
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Signature sheet for the foregoing Craig Road Landfill Record of Decision between the U.S. Air
Force and the U.S. Environmental Protection Agency, with concurrence by the Washington State
Department of Ecology.
-
~.
')
/J~(J KA~~
Dana Rasmussen
Regional Administrator, Region X
U.S. Environmental Protection Agency
FEB J 1 1993
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Signature sheet for the foregoing Craig Road Landfill Record of Decision between the U.S. Air
Force and the U.S. Environmental Protection Agency, with concurrence by the Washington State
Department of Ecology.
;M
~
11.
13faCf3
Date
ames M. Richards
Brigadier General, USAF
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Signature sheet for the foregoing Craig Road Landfill Record of Decision between the U.S. Air
Force and the U.S. Environmental Protection Agency, with concurrence by the Washington State
Department of Ecology.
~.;f. L1-J~..f~
Carol L. Fleskes, Program Manager
Toxics Cleanup Program
Washington State Department of Ecology
:;../s.jq~
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DECISION SUMMARY
INTRODUCTION
.
Fairchild Air Force Base (AFB) was listed on the National Priorities List (NPL) in March 1989
under CERCLA, as amended by SARA. The Craig Road Landfill (CRL) site at Fairchild AFB
comprises the first operable unit for which a cleanup action has been selected.
In accordance with Executive: Order 12580 (Superfund Implementation) and the NCP, the
Department of the Air Force performed a Remedial Investigation (RI) for the CRL, which
characterized the nature and extent of contamination in groundwater, soils, and air near the
landfill. A baseline risk assessment, comprised of a human health risk assessment and an
ecological risk assessment, was conducted as part of the RI to evaluate current and potential
effects of the landfill contaminants on human health and the environment.
I. SITE LOCATION AND DESCRIPI10N
Fairchild AFB is located approximately 12 miles west of Spokane, Washington. The CRL is
located on property owned and operated by the U.S. Air Force as part of the Fairchild AFB
installation. This property occupies approximately 100 acres and is located on the west side of
Craig Road (Figure 1) approximately 0.7 mile south of U.S. Route 2 and 0.6 mile east of
Rambo Road.
The CRL contains three inactive waste disposal areas. Municipal and industrial wastes were
buried in trenches on about 6 acres in the northeast corner and in a low area of about 13 acres
in the southwest corner. Demolition debris from the runway reconstruction was deposited on the
ground surface in the southeast comer covering an area of about 20 acres (Figure 2).
The Base wastewater treatment plant (WWTP) is located in the northwest corner of the property
(Figure 2). Treated wastewater from the plant is discharged to an infiltration pond and a series
of percolation trenches located on the landfill property adjacent to the northeast disposal area.
ll. SITE HISTORY AND ENFORCEMENT
The CRL was a former disposal location for Fairchild AFB and was used for general purpose
landfilling. Detailed documentation of waste types disposed within the CRL does not exist.
However, waste types reportedly included miscellaneous sanitary and industrial waste, and
construction and demolition debris. Various specific items suspected'of disposal in the CRL are
Coal ash from the power plants, solvents, dry cleaning filters, paints, thinners, and possibly
electrical transformers.
The northeast landfill area was active from the late 19505 into the early 19605. Landfilling in
this area proceeded by trench-and-fill, soil cover, and grading. Depths of landfilling, based on
soil borings, exceed 30 feet below the existing ground surface.
FAFBICRI.IROD - 02101/93
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EXPLANATION
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DRAINAGE TRENCH
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APPROXIMATE LANDFILL LIMITS
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SURFACE WATER
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CRAIG ROAD ( ) / I S!
LANDFILL I ~_./ / :
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Figure 2.
Inactive Waste Disposal Areas and
Pond and Drainage System at CRL
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The southwest landfill area was active from the late 1960s into the late 1970s. Disposal methods
consisted of fill-and-cover in a topographical low area, possibly with some excavation. The soil
cover was graded and then overlain in areas with concrete blocks and asphalt from the runway
reconstruction. Depth of landfilling in this area, based on soil borings, is estimated to exceed
25 feet below the present ground surface.
Environmental problems associated with the CRL were discovered under the U.S. Air Force
Installation Restoration Program (IRP). This program was initiated through the 1981 Executive
Order 12316 that directed the military branches to design their own program of compliance with
the NCP established by CERCLA. In order to respond to the changes in the NCP brought about
by SARA, the IRP was modified in November 1986 to provide for a Remedial Investigation!
Feasibility Study (RIfFS) Program to improve continuity in the site investigation and remedial
planning process for Air Force installations.
Environmental investigations of past hazardous waste disposal practices and sites were initiated
at Fairchild AFB in 1984 as part of the Air Force IRP. In 1985, the first report summarizing
IRP investigations at Fairchild AFB was published. Preliminary findings in this report identified
the CRL (formerly referred to as IRP Site SW-8) for additional investigation, which has
continued and will continue. through the remediation of the site.
In 1987, EPA scored the Fairchild AFB (based on four sites) using their Hazard Ranking System
(HRS). As a result of the HRS scoring, Fairchild AFB, including the CRL, was added to the
NFL in March 1989. In response to the NPL designation, the Air Force, EPA, and Ecology
entered into a Federal Facility Interagency Agreement (FFA) in March 1990. The FFA
established a procedural framework and schedule for developing, implementing, and monitoring
appropriate response actions conducted at Fairchild AFB.
In order to facilitate the CERCLA process, potential source areas at the Base have been grouped
into operable units. The remedial investigation for eaCh operable unit has a separate .schedule.
The CRL operable unit is the first operable unit for which a cleanup action has been selected.
Under the terms of the FFA, EPA and Ecology provided oversight of subsequent RI activities
and agreement on the final remedy for this ROD.
Off-base residential wells near the CRL were sampled in 1989 as part of the RI. Sampling
results indicated that the wells, located directly northeast of the CRL, were contaminated with
trichloroethene (TCE) above federal maximum contaminant levels (MCLs), which are drinking
water standards established by the Safe Drinking Water Act. The Air Force immediately
connected these off-base residents to an alternative uncontaminated water supply system.
In 1991, the Air Force initiated a Removal Action at the site and began the development of a
system to pump water from the upper aquifer and remove the contaminants. This action was
initiated to minimize off-site release of contaminants found in the groundwater beneath the
landfill. Initial activities performed as part of the removal action included drilling, completion,
and some testing of a total of nine extraction wells from the northeast and southwest fill areas.
FAFBICWROD . 02101/93
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In addition, an air stripping treatment unit was constructed on site to treat extracted
groundwater. This system became operational in October 1992.
.(
Construction of a pipeline to divert wastewater from the Base WWTP to the Spokane Regional
WWfp is currently underway. Completion of this system, estimated for February 1993, will
eliminate the discharge of treated effluent from the Base WWI'P to the infiltration pond and
trenches on the landfill property. .
ID. mGHLIGHTS OF COMMUNITY PARTICIPATION
The Air Force developed a Community Relations Plan (CRP) in March 1990 as pan of the
overall management plan for the CRL RIlFS. The CRP was designed to promote public
awareness of the investigations and public involvement in the decision-making process. The
CRP summarizes concerns that Fairchild AFB, in coordination with EP A and Ecology, is aware
of based on community interviews and comments obtained at a public workshop. Since this
initial workshop Fairchild AFB has sent out numerous fact sheets and has held annual workshops
in an effort to keep the public informed and to hear concerns on the CRL issues. The CRP was
updated in September 1992.
On July 1, 1991, Fairchild AFB made available for public review and comment the draft
Engineering Evaluation/Cost Analysis (EElCA) that recommended a removal action for
contaminated groundwater at the CRL. The public was notified of this document's availability
through a fact sheet mailed to local, interested persons and in a public announcement published
in The Spokesman-Review. The public comment period ended July 31, 1991.
The RI Report for the CRL was released to the public in April 1992; the FS and Proposed Plan
were released on August 10, 1992. These documents, as well as previous reports from the
RIlFS investigation, were made available to the public in both the Administrative Record and
the Information Repository maintained at the locations listed below:
ADMINISTRATIVE RECORD (contains all project deliverables):
Fairchild AFB Library
Building 716
Fairchild AFB, WA 99011
Spokane Falls Community College library
W. 3410 Fon George Wright Drive
Spokane, W A 99204
INFORMATION REPOSITORY (contains limited documentation):
Airway Heights City Hall
S. 1208 Lundstrom
. Airway Heights, WA 99101
FAfBlCRUROD - 02101193
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The notice of the availability of these documents was published in The Spokesman-Review on
August 9, 1992. The public comment period was held from August 10, 1992, through
September 8, 1992. In addition, a public meeting was held on August 25, 1992. At this
meeting, representatives from the Air Force, EPA, and Ecology answered questions about
problems at the site and the remedial alternatives under consideration. A response to the
comments received during the public comment period is included in the Responsiveness
Summary, which is part of this ROD. This decision document presents the selected remedial
action for the CRL at Fairchild AFB, Spokane, Washington, chosen in accordance with
CERCLA, as amended by SARA, and to the extent practicable, the NCP. The decision for this
site is based on the Administrative Record. .
-
v
".
IV. SCOPE AND ROLE OF RESPONSE ACTION WITHIN SITE STRATEGY
Potential source areas at Fairchild AFB have been grouped into separate operable units. A
different schedule has been established for the operable units. The CRL site comprises the first
operable unit at Fairchild AFB for which a final cleanup action has been selected. Selection of
cleanup actions for five operable units is scheduled to be made in the spring of 1993 and, for
the remaining operable units, in the spring of 1995.
The cleanup actions for the CRL described in this ROD address both on-site and off-site
groundwater contamination and source areas associated with subsurface disposal at the site. A
groundwater extraction and treatment action was initiated at this site in 1991 as part of a removal
action. The groundwater cleanup actions described in this ROD are consistent with and will
expand upon the existing groundwater treatment system. The cleanup actions described in this
ROD address all known current and potential risks to human health and the environment
associated with the CRL site.
V. SUMMARy OF SITE CHARACTERISTICS
The center of the city of Airway Heights is approximately 0.5 mile northeast of the CRL and
its western city limit coincides with Craig Road. The current population of Airway Heights is
approximately 2,000. Land use in the vicinity of the CRL is primarily agricultural, with the
exception of housing developments within Airway Heights and some small trailer parks beyond
the city limits. One mobile home park, housing about 135 residents, is located approximately
1,500 feet from the southwest fill area. Other land uses surrounding the CRL include surface
mining for sand and gravel and light industry. No historical or archeological resources are
located within the CRL boundaries. In addition, the site is not within a lOO-year floodplain.
The upper and lower basalt aquifers in the immediate vicinity and downgradient of the site are
used for residential and municipal water supplies. Four residential wells are located within I
miles downgradient of the site. Municipal drinking water wells for the city of Airway Heights
are located approximately 5,000 feet downgradient of the site.
FAFBICRUROD - 02101193
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A. Site Geology and Hydrogeology
..
The CRL is situated on the northeastern edge of the Columbia Plateau about 5 miles west of
Spokane. The Columbia Plateau is composed of a thick sequence of Tertiary-aged lava flows
known as the Columbia River Basalt Group. Average elevation at the site is approximately
2,390 feet above mean sea level (msl). The topography surrounding the CRL is relatively flat
and slopes gently to the southeast, east, and northeast (FIgUre 3). The area surrounding the
landfill is drained by poorly defined, small, intermittent drainageways that have been modified
locally into man-made ditches. There are a few drainage trenches (used for infiltration of
discharge from the Base WWI'P) within the property boundaries defining the landfill; none leave
the site (Figure 3). All surface water related to the site either evaporates or mfiltrates into the
soil on the CRL.
Groundwater investigations wc~re limited to the top two aquifers. The upper aquifer is comprised
of the uppermost, highly fractured basalt layer (Basalt Flow A) and the overlying alluvium. The
water table of the upper aquifer roughly coincides with the bedrock surface. The Basalt Flow
A thickness ranges from 90 to 140 feet. The depth to the current water table (prior to tUrning
off the WWTP) ranges from 15 feet below ground surface (bgs) beneath the CRL to 50 feet bgs
at the eastern boundary of the landfill to 150 feet bgs in the channel. .
A 16- to 2Q-foot low permeability clay interbed, Interbed A, separates the upper aquifer fr.om
the deeper, underlying aquifer in Basalt Flow B. Basalt Flow B is approximately 180 feet thick
and is confined where capped by Interbed A. The depth to the potentiometric surface of the
lower aquifer ranges from 130 to 150 feet bgs. In general, there is no flow from the upper
aquifer into the lower aquifer except where Interbed A has been breached. One known breach
in Interbed A has occurred in the unused residential wells to the northeast of the CRL boundary;
a potential breach could be along the suspected fault to the south of the landfill.
East of the CRL, the Basalt Flow A and Interbed A are cut by a channel and replaced by a thick
sequence of alluvial sand and gravel. FIgUre 4 shows the shape of the bedrock surface and
position of the channel. The inset diagrammatic cross section illustrates the approximate shape
and depth of the channel. The water table elevation in the channel averages approximately 2,250
feet above mean sea level (msl), while the water table elevation at the CRL is approximately
2,350 feet above msl (FIgUre ~1. This relatively large difference in water levels between the
CRL and the channel result in large hydraulic gradients east toward the channel. Therefore, the
dominant controls on groundwater flow direction are the shape of the bedrock surface and water
level in the channel. FIgUre 6 shows the general relationship between the Basalt A and Basalt
B aquifers.
Local flow deviations from the general groundwater flow direction may occur within discrete
fractures or fracture zones if the fracture orientation differs from the general groundwater flow
direction. However, these differences average out and on the large scale the fractured media
behaves as an equivalent porous medium. Hydraulic conductivities from slug tests on
monitoring wells at the CRL mnged from 0.3 to 8.6 ftIday. These values are close to the
median hydraulic conductivity of 3.3 ftIday for the Columbia River Basalt Group. Trans-
FAFBICRUROD . 0'2101/93
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T
25
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TOPOGRAPHIC t'ONTOUR ELEVATION IN
FE£T ABOVE MSL
.---.
APPROIt. LOCAfiON OF REGIONAL SURFACE WATER ANO
GROUNDwATER OIVIOES (OIVIOE~ ROUGIIL Y
COINCIDE)
..... -...
APPROX. A)ClS OF TOPOGRAPltlC LOW. ARROWS
INDICATE GENERIIL DIRECTION OF StOPE.
-----
FAIRCHILD AFB PROPERTY BOUNDARY
Figure 3.
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-------
missivity values calculated from conductivity and thickness of Basalt Flow A range from 27 to
1,200 square feet per day (ft2/day).
<'i
"
The upper aquifer underlying the CRL is recharged from either discharge from the WWTP or
precipitation that infiltrates through the landfill. Due to the recharge by approximately 1 million
gallons per day of effluent from the Base WWTP to the infiltration pond and trenches, there is
a local mounding of the water table in the upper aquifer below the CRL (Figure 5). As part of
,
0/.1
Fairchild AFB's near-tenn plans, the existing Base WWTP will be closed and the effluent
diverted to the city of Spokane publicly owned treatment works (p01W). The net hydrologic
effect should be the elimination of the existing groundwater mound. Groundwater flow direction
will still be east toward the channel.
B. Nature and Extent of ContJlmin9tioD
The two landfilled areas (northeast and southwest) within the CRL are the apparent sources of
contamination at the site. The southeast landfill area was used for surface disposal of concrete
debris from the runway reconstruction and has not been identified as a source of environmental
contamination.
1. Groundwater
Groundwater samples were collected from 42 monitoring wells over 10 sampling rounds, which
took place from 1986 through 1991. Of these 42 wells, 36 were screened in the upper aquifer,
while 6 were screened in the lower Basalt B aquifer. A total of 17 monitoring wells were
completed in the upper aquifer directly below the CRL property; only one well was completed
in the lower aquifer below the site. All the remaining monitoring wells were installed beyond
the CRL boundary. Sampling was conducted during each year (except 1988) on a varied
schedule in order to accommodate both wet and dry season sampling. Samples we~ analyzed
for volatile organic chemicals (VOCs) and semi-volatile organic chemicals (SVOC), metals, and
common anions. .
Ba~lt A Aauifer
VOCs detected in groundwater samples included vinyl chloride, l,l-dichloroethene (l,l-DCE),
1,I-dichloroethane (1, I-DCA), trans-l,2-dichloroethene (t-l ,2-DCE), 1,1, I-trichloroethane
(l, 1,1- TCA), TCE, benzene, tetrachloroethene (PCE), toluene, and chlorobenzene. Table 1
presents the detected compounds. SVOCs detected in groundwater samples, also presented in
Table 1, were phenol, 1,4-dichlorobenzene (l,4-DCB), bis(2-ethylhexyl)phthalate (BEHP), and
acetophenone. Although several metals were detected in groundwater samples, none were
detected in concentrations exceeding background levels.
OJ
FAFBICRlJROD. OVOI193
-------
"
Table 1
Fairchild AFB - Craig Road Landfill
Summary of Groundwater Sampling Results
Organic Compounds (ugll)
Frequency 01 Range 01 Mean 01 Range 01
Analyte Detection (at) Concentrations Concentrations Detection Limits
VOCs in
Upper Aquiler:
Benzene 1/110 0.6 0.6 0.2-5
Chlorobenzene 1/110 0.3 0.3 0.2-5
1,1-Dichloroethane 1/110 0.3 0.3 0.07-5
1,1-Dichloroethene 1/110 0.8 0.8 0.13-5
t-1.2-Dichloroethene 3/110 4-54 34 0.3-2
T etrachloroethene 2/110 0.4-0.7 0.6 0.03-5
Toluene 3/110 0.2-0.5 0.3 0.2-5
1,1,1- Trichloroethane 1/110 0.4 0.4 0.03- 1
Trichloroethene 55/110 0.3-2800 319 0.12-5
Vinyf chloride 1/110 2 2 0.18-10
VOCs in
Lower Aquifer:
Trichloroethene 6/16 4-67 18 0.12-5
SVOCs in
Upper Aquiler:
Acetophenone 2/83 19-22 20 3-50
BB-tP 5/83 7-53 19 1-10
1.4-Dlchlorobenzene 1/83 1 1 0.3-10
SVOCs In
Lower Aquifer:
Phenol 1/8 7 7 3-10
(a) Frequency of Detection - number of detections/number of
samples analyzed, including field duplicates.
-------
Background levels were derived from 23 groundwater samples collected from 11 monitoring
wells installed in locations not suspected to have been effected by inorganic contamination. The
method chosen to determine background levels was the upper 95 percent tolerance limit,
calculated at a 95 percent confidence level in accordance with EP A guidance.
v
u.
TCE is the most predominant contaminant in groundwater associated with the CRL. FIgUre 7
shows estimated levels of TCE in the upper aquifer, based on information from monitoring
wells. Table 2 presents the groundwater area/volume calculations for the concentration intervals
shown in Figure 7.
..r
The other halogenated aliphatic compounds detected in groundwater samples collected at the
CRL (vinyl chloride, PCE, I,I-DCE, I,I-DCA, t-I,2-DCE, and 1,I,I-TCA) were all detected
in relatively small concentrations (S4 ug/L) and in very few samples (S3). Because of the
high migration potential of these compounds in groundwater, it appears that they are either not
present in large quantities in the landfill or, if they are, their containers have remained intact for
a longer period of time than those holding TCE. Biodegradation products of TCE include 1, 1-
DCE, t-I,2-DCE, and vinyl chloride. Under more typical circumstances these analytes would
be found in high~r concentrations within the TCE plume. The lack of these contaminants in
groundwater at the site is likely due to the somewhat sterile characteristics of the fractured basalt
in which methanogenic anaerobic bacteria could not flourish.
At the CRL benzene was detected in one groundwater sample collected from a monitoring well
installed approximately 4,800 feet southeast of the southeast comer of CRL, which appears to
be installed in a southern ann of the alluvial channel that lies to the east of the CRL. Benzene
is a LNAPL and migrates or disperses rapidly through an aquifer. Although benzene was
detected at the landfill during the soil-gas survey, the CRL is an unlikely source of benzene in
this well due to the relatively large distance between the well and the landfill. In addition,
because benzene is a component of petroleum products, there are other possible benzene sources
that exist closer to where it was detected. .
The other fuel components detected during the soil-gas survey (toluene, ethylbenzene, and
xylenes) were either absent or detected in very small quantities (Table 1) in groundwater samples
collected from the Basalt A aquifer. Their high vapor pressure and relatively low water
solubility accounts for this observation. It is unlikely that these analytes would migrate into the
groundwater in high concentrations unless the soil pore spaces became saturated and their
upward mobility became blocked.
Ba~1t B Aauifer
The six monitoring wells installed in the Basalt B aquifer were sampled during 1990 and 1991.
Six samples (including one duplicate) were collected from MW-74, four during 1990 and two
during 1991. Three groundwater samples (one during 1990 and two during 1991) were collected
from MW-79. MW-101 was sampled on three occasions during 1991; MW-126 on two
occasions. Both MW-135 and MW-136 were sampled during the final sampling round in 1991.
FAFBfCRUROD - 02101/93
-------
.,
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I [KPLAPjATIOPj
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-------
Table 2. Area/Volume Calculallons
For Groundwater. CAl Fairchild "FB
Concentration Awrage ToIa' Waler Waler Ma.. 0'
Interval. Concenlrallon "rea VoIume(a) VoIume(b) VoIume(c) TCE(d) TCE(e)
b.1.000 1.1500 70.000 7,000,000 700,000 18.821,800 2.87E+01 5
500 - 1,000 0.750 1.800.000.000 1110.000,000 18.000.000 538.023,000 4.04E+02 73
250 - 1500 0.376 1.700.000.000 170.000,000 17.000.000 481.388,000 1.81E+02 33
4-250 0.127 5,500,000 500.000,000 55,000.000 1,557.435.000 1.118 E+02 38
1-4 0.003 12.800.000 1.250,000.000 128.000.000 3.687.842,000 1.07E+01 2
0-
0\
a) Area X 100 It lalurated thlckne.. (awrage)
b) Tolal volume X 10.. porOl/ty
c) Conwrelon: 2'.3171Iter/ou It
d) Water volume (l) X Iwrloe concentrallon (mg/l) X 1E10~ Kg/mg
e) Conwrelon to Oillone: TCE denelty. 1.48; mils TCE(KO)l1.480 Kgll X 0.2842 O.IIl
\ ,
-------
TCE was the only VQC detected in groundwater samples collected from the lower aquifer (see
Table 1). This analyte was detected in six samples in concentrations ranging from 4 to 67 p.g/L.
The only Basalt B well found to contain TCE was MW-74, which is located in the northeast
comer of the CRL (Figyre 6). This is just downgradient of where the highest concentrations of
TCE were detected in the upper aquifer (MW-85) and where known breaches between the upper
and lower aquifers exist in the unused residential wells at the mobile home park.
The SVOC phenol (7 Jlg/L) was detected in one groundwater sample collected from MW-126,
which appears to be located on the east side of the alluvial channel (see Figure 5). The presents
of phenol in this well is not likely associated with contaminants derived from' the CRL.
Residential and MuniciDal WeUs
A total of 18 residential wells were sampled on an irregular basis between 1989 and 1991. Nine
of these residential draw water from the upper aquifer, two from the lower aquifer, two. from
the channel, and the remainder from either an interbed or from an unknown depth. Groundwater
collected from these wells was analyzed primarily for TCE. There are only two municipal
water supply wells (city of Airway Heights wells RW-l and RW-4, completed in the channel)
and one private well (RW-7, C'..ompleted in the upper aquifer), serving a light industrial site,
currently in use that have been affected by TCE. The level of contamination in these well~ is
below the federal MCLs and is considered safe for drinking water use. These wells are
currently sampled on a quarterly basis to monitor for contaminants. Users of these wells would
be notified if TCE levels in their well rose above MCLs. TCE was detected in three water
supply wells that served the mobile home park located just northeast of the northeast fill area
in concentrations exceeding the MCL. These wells have since been closed for supply purposes
and the residents from the mobile home park presently are supplied with water from the Base.
2. Soils
Historical aerial photographs indicate that landfilled materials were placed in trenches in the
northeast and southwest comers of the CRL site and were subsequently covered with native
soils. Test pits excavated as part of the remedial investigation indicate that an average of 3 feet
of soil covers the two fill areas. Since native soils were placed over the refuse after landfill
operations were terminated, surface soil contamination at the site is not suspected and this
medium was not sampled during the remedial investigation.
Groundwater data indicate that contaminants leach from the buried landfilled material into the
subsurface soil. An attempt was made to collect samples of contaminated subsurface soil located
beneath the buried landfilled material during a soil boring program. In all instances, sampling
attempts failed due to bit refusal within the landfill material. The base of the fill material is
estimated to be at 20 to 25 feet below ground surface in the southwest area and at 30 to 35 feet
in the northeast area.
FAFBICRUROD - 02101/93
-------
A soil-gas survey performed at the site detected numerous volatile organic compounds (VOCs)
believed to be buried within the landfill. Compounds typically associated with fuels and fuel
products and components of cleaning solvents (i.e., benzene, toluene, ethylbenzene, xylenes and
TCE) were detected. The results of the soil-gas survey, discussed under air results, are
indicative (at least in part) of the subsurface soil contamination in these two areas.
J'
,~
.
J-
The boundaries of the northeast and southwest source areas were determined by aerial
photography, geophysical surveys, and borings. Average landfill and soil thicknesses from
borings and planimeter measurements of landfill areas were used to estimate source volumes.
The sizes of potentially contaminated areas within the fill boundaries were also. estimated by the
planimeter method using the contours from the soil-gas survey (FIgUre 8). Table 3 summarizes
the area and volume calculations of the contaminant source areas.
3. Surface Water/Sediments
Perennial surface water found on site is associated with the WWTP and either evaporates or
infiltrates into the ground, hydraulically upgradient of the landfilled areas. No surface water
comes into contact with the waste, since once it infiltrates into the landfill it becomes
groundwater. In addition, there is low annual precipitation, a high evapotranspiration rate,
highly permeable surface soil, and no surface drainage leaving the site. Therefore, surface water
and sediments were not considered affected media and did not undergo extensive environmental
sampling.
4. Air
No formal ambient air monitoring was performed at the CRL due to the site's proximity to the
flight path at the Base. However, the site was surveyed for VOCs using an HNu, and a soil-gas
survey was conducted. Background levels from the breathing zone (2 meters above ground
surface) ranged from 0 to 2 ppm VOCs. VOCs were detected at 44 of the 149 soil-g~ sampling
locations that covered the northeast and southwest fill areas.
In the northeast area, the maximum soil-gas concentrations detected were 380 pans per billion
by volume (Ppbv) for l,l-DCA and 56,000 ppbY for TCE. One estimated value each was
reported for toluene (31 ppbY) and methylene chloride (340 ppbv). In the southwest fill area
three contaminant hot spots were identified, with the central hot spot containing the highest
concentrations (TCE, 96,OOOppbv; l,l-DCE, 17,000; l,l-DCA, l5,OOOppbv; xylenes, 460,000
ppbv; ethylbenzene, 140,000; benzene, 18,000 ppbY; toluene, 53,000 ppbv; methylene chloride,
4,400 ppbv).
FAfBlCRUROD. 02101/93
-------
r
EXPLANATION
-...-
DRAINAGE TRENCH
--
----
APPROXIMATE LANDFILL LIMITS
.:
".
&//d
1.;,}!!::;::!:i:1
SURFACE WATER
~
AREA OF SOIL - GAS DETECT I ON S
NORTHEAST
LANDFILL
AREA
r-.
r-- -
. -,
WWTP I
- 0 0 --.'.~" I
I 00° 0° . \ I ~:I
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~ ::, II~
CRAIG ROAD 1--- ~ --II j i / I:
LANDFILL II ~~./ / I 5
d ,.' / II
I \ / I
I l r
SOUTHWEST \ I CONSTRUCTION I
LANDFILL I ;/ DEBRIS
AREA ~' I AREA I
I I
I --..) L.-- ~
.,.---- - ~
L- --:- --~~
21 ST AVENUE
Me FARLANE ROAD
~
,...
Figure 8.
Areas of Approximate Landfill Locations and Soil-Gas Detections
19
, I
II
I:
@
o
500 FEET
SCALE
-------
Table 3. Area and Volume Estimates Associated with Buried Landfill Sources
N
o
NE AREA SW AREA
Disposal Area 262,000 sq. ft. 549.900 sq. ft.
(6 acres) (12.6 acres)
Average Thickness 30 ft. 20 ft.
of Refuse
Refuse Volume 7,860.000 cu. ft. 10.998.000 cu. ft.
(291.000 cu. yd.) (407.300 cu. yd.)
Volume of Refuse Potentially 3.603,000 cu. ft. 4.779.000 cu. ft.
Contaminated by VOCs Based (133.400 cu. yd.) (177.000 cu. yd.)
on Soli-Gas Contours
Average Depth to Bedrock 45 ft. 25-30 ft.
Estimated Thickness of Soli 15 ft. 5 ft.
between Refuse and Bedrock
Estimated Volume of Potentially 3.931.200 cu. ft. 2,748.600 cu. ft.
Contaminated Soli below Refuse (145,600 cu. yd.) (101.800 cu. yd.)
I .,
, I
-------
VI. SUMMARY OF SITE RISKS
CERCLA response actions at the CRL site as described in the ROD are intended to protect
human health and the environment from risks related to current and potential exposure to
hazardous substances at the site.
To assess the risk posed by site contamination, a Baseline Risk Assessment was completed as
part of the Remedial Investigation. The human health risk assessment for the CRL considered
potential effects of the site-related contaminants on human health and the ecological risk
assessment evaluated potential risks to the environment. The risk assessment$ were conducted
in accordance with EPA's Risk Assessment Guidance 'for Superfund. Volume I: Human
Health Evaluation ManuallRAGS HHEMI and Volume ll: Environmental Assessment Manual,
other EP A national guidance, and EP A Region 10 Supplemental Risk Assessment Guidance for
Superfund. This section of the ROD summarizes the results of the Baseline Risk Assessment
for the CRL site.
A. Human Health Risks
The human health risk assessment considered potential risks associated with exposure to CRL
site contaminants. The asseSsment involved a four-step process that included the identification
of contaminants of concern, an assessment of contaminant toxicity, an exposure assessment of
the population at risk, and a characterization of the magnitude of risk.
1. Identification of Chemicals of Potential Concern
Potential contaminants of concern for the CRL site were identified as chemicals detected in
groundwater in the vicinity of the site and in soil-gas samples taken from the northeast and
southwest fill areas.
a. Groundwater
Potential chemical of concern in groundwater were subjected to a risk-based screening process
to identify chemicals to be included in the quantitative risk assessment. Risk-based
concentrations (RBCs) were calculated according to Risk Assessment Guidance for Su,perfund.
fm:1Jl. Table 4 lists the RBCs calculated for the organic contaminants that were detected in
groundwater samples collected from monitoring wells associated with the CRL. The maximum
concentrations of TCE, 1,I-DCE, vinyl chloride, and BEHP detected in groundwater exceeded
their respective screening levels.
Rationale for the selection of specific contaminants of concern for groundwater are discussed
below.
FAfBlCRlJROD . 02101/93
-------
TABLE 4
SCREENING OF GROUNDWATER CONTAMINANTS
CRAIG ROAD LANDFill, FAIRCHilD AFB
.. ..
. "..
.. -
TCl - -. --... -.--
No; Chemlcali
......
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.. . "'""""" . .
. "0' ..... '"
".. ... .. ,.. ''''''.. .. .
':::~::::.:.:.: ':::::)~{:;;:fjdit.f:~:!:::~::<':;': .-.".,' . .: Weight
j.!~J!~fJi~«8> .
... . . .. n..
. """" .
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. .. ......... ....
- -- -- ----.------ - -FreqH~.
- -Risk-BciSedConceniratl0n8.ofDet~tI~
DU -. . Risk. 1 0'-6 Alsk..10':4 HI-0.1 - - --- All Wella ~ -. ---
.. -- Fr~u~y
_.Of Qetectloris
--.-. Souridary-
- Wells (c)
Include -
InRA
Rationale
'.. n.
--
Organic Compounds (Concentrations In ugll):
3 Vinyl chloride 2 2 0 A 0.18-5 0.03 3 NA 1/126 (0.8%) (d) yes Exceeds 10-6 ABC (e)
8 1,1-Dlchloroethene 0.8 7 7 C 0.13-2 0.07 7 30 1/126 (0.8%) 1/38 (2.6%) yes Exceeds 10-6 ABC (e)
9 1,1-Dlchlor08thane 0.3 NA NA C 0.07-2 NA NA 80 1/126 (0.8%) 1/38 (2.6%) no Less Ihan ABC
10 trans-1,2-Dlchlor08thene 54 100 100 no dala 0.1-2 NA NA 70 31126 (2.4%) 3138 (7.8%) 00 less than RBC
14 1,1,1- Trichloroethane 0.4 200 200 D 0.03-3 NA NA 200 1/126 (0.8%) 1/38 (2.6%) no less than RBC
20 Trlchloroethene 2800 5 0 B2 0.12-2 3 300 NA 61/126 (48%) 35138 (92%) yes exceeds RBC
~ 23 Benzene 0.6 5 0 A 0.2-1 0.6 60 1 1/126 (0.8%) (d) no Equal to 10-6 ABC (I)
28 Tetrachloroethene 0.7 5 0 B2 0.03-2 1 100 40 2/126(1.6%) 1/38 (2.6%) no Less than RBC
- 29 Toluene 0.2 1000 1000 D 0.2-2 NA NA 300 31126 (2.4%) (d) no Less than RBC
31 Chlorobenzene 0.3 100 100 D 0.2-2 NA NA 5 1/126 (0.8~) (d) no less than ABC
3S Phenol 7 NA NA D 2-10 NA NA 2000 1/126 (0.8%) (d) no Less than RBC
39 1,4-Dlchlorobenzene 1 75 75 C 1-10 3 300 200 1/126 (0.8") (d) no less than ABC
92 BIs(2-ethylhexyl)phthalate 53J 4 (g) 0 (g) B2 1-10 6 600 70 5/91 (5.5%) 4129 (14%) yes Exceeds 10-6 RBC
Acetophenone 22 NA NA NA 3 NA NA 37037 2/91(2.2%) 1/29 (3.4%) no less than ABC
(a) - Weight of evidence Is an EPA cl888lflcatlon for characterlzfng the extent to which the
available data Indicate that an agent Is a human carcinogen.
(b) - Duplicate samples are Included In Iolai.
(c) - Well selection based on location of well In Basalt Flow A at site boundary:
MW-63,MW-69,MW-75,MW-78,MW-77,MW-85,MW-96,MW-140
(d) - Analyte nol detected In any bOUndary well. -
(8) - Detection limits were greater than ABCs.
(I) - Other evidence Is available for excluding benzene from RA; see explanation In text.
(g) - Proposed MCL
J - Concentration In duplicate sample Is 20 ugIL; RPD - 9OIMI.
Dls - Range of detection limits. -
-------
Trichloroethene
TCE was found to be the most predominant and wide-spread contaminant associated with the
site. TCE concentrations exceeding the RBC of 3 ug/L were detected in many groundwater
samples collected from wells installed to monitor groundwater quality in the Basalt A aquifer.
The peak TCE concentration of 2,800 ug/L was detected in monitoring well MW-85, located
off site, north of the northeast contaminant source area. The highest concentration found at a
distance from the site was 490 ug/L, detected in the downgradient well MW-1l8, which is
located approximately 2,000 feet due east of the landfill boundary. In addition, TCE
concentrations from three downgradient, off-base residential water supply well~ (RW-9, RW-IO,
and RW-ll), all located within 700 feet to the northeast of the site, ranged from 57 to 79 ug/L.
1.1-Dichloroethene
1, I-DCE was detected at 0.8 ugIL in one groundwater sample collected from MW-69 during the
last sampling round; this exceeds the RBC of 0.07 ug/L. The contaminant was not detected in
groundwater from any monitoring wells during the four previous sampling rounds. The
analytical detection limit for this analyte ranged from 0.2 to 5 ug/L, which exceed the RBC.
I,I-DCE is a breakdown product of TCE; therefore, TCE could act as a potential source of
I, I-DCE in groundwater ove:T time. This chemical was included in the quantitative risk
assessment.
Vinvl Chloride
Vinyl chloride was detected at 2 ug/L in groundwater collected from MW-18 during round 4.
This well was not sampled dwring following sampling rounds due to mechanical difficulties in
the well. Vinyl chloride W"clS not detected in other monitoring wells over 10 rounds of
groundwater sampling; however, the detection limit for vinyl chloride during most of these
rounds exceeded the risk-based concentration and the federal MCL. Since vinyl chloride is a
breakdown product of TCE, groundwater contaminated with TCE could act as a source of vinyl
chloride in this medium over time. Therefore, this analyte was included in the quantitative risk
assessment.
bis(2-EtbvlhexvOpbthalate
BEHP was detected in five groundwater samples (including one field duplicate) during the
remedial investigation. The maximum concentration of BEHP detected at the site was 53 ug/L
in monitoring well MW-69. All four detections exceeded the RBC of 6 ugIL. BEHP is a
common plasticizer; it is not clear whether BEHP is associated with waste disposal at the CRL
site or with field and/or laboratory contamination. Due to the uncertainty of the source of
BEHP, this analyte was carried through the risk assessment.
Benzene
Benzene was detected at the RBC level in one groundwater sample collected from monitoring
. well MW-138, located approxiimately 4,800 feet southeast of the southeast comer of the CRL.
FAfBlCRlIROD - 02101/93
-------
Although benzene was detected at the landfill during the soil-gas survey, the CRL is an unlikely
source of benzene in this well due to 1) the relatively large distance between the monitoring well
and the site and 2) the lack of benzene detection in monitoring wells located in the immediate
vicinity of the fill areas. Since benzene is a component of common petroleum products, there
may be other possible benzene sources in the vicinity of monitoring well MW-138. Therefore,
benzene was not carried through the risk assessment.
..7
~
JP
Inon!anics
Inorganic background levels for the Basalt A aquifer were statistically determined for aluminum,
barium, iron and manganese. Groundwater metal concentrations in wells located at the site
boundary and downgradient of the CRL were screened against the calculated background levels.
Background levels could not be calculated for the remaining metals; therefore, statistical
comparisons were made to determine whether groundwater metal concentrations downgradient
of the site were different from levels found upgradient of the site. Based on these screening
processes, metals were not identified as contaminants of concern for the risk assessment.
b. Air
Data collected from soil-gas measurements from the northeast and southwest fill areas were used
to model contaminant emissions from these areas. The following maximum soil-gas
concentrations detected- during the soil-gas survey (measured in uglcm3) were used as input
parameters for the model:
Location
NE
NE
NE
SW
SW
SW
Compound
Benzene
Methylene chloride
TCE
Benzene
Methylene chloride
TCE
Concentration
l.OxlQ4
1.3xlo-3
3.Oxlo-1
1.9
5.2xlO.2
5.2x1o-1
2. Exposure Assessment
The exposure assessment identified potential pathways for contaminants of concern to reach the
exposed population. The conceptual site model shown in FJgUre 9 identifies contaminant
sources, release/transport mechanisms, affected media, exposure points, exposure routes, and
potential receptors for the site. The conceptual site model was used as the basis for identifying
the potential exposure pathways addressed in the Baseline Risk Assessment.
a. Exposure Pathways
Groundwater
Contaminants that leach from the two fill areas have affected the groundwater quality beneath
and downgradient of the landfill. Ingestion of groundwater is the primary exposure pathway for
FAFBICRUROD. 02101/93
-------
CONTAMINANT
SOURCE
MUNICIPAL
INDUSTRIAL.
COMMERCIAL.
HAlAADOUS
WASTES
N
VI
OONTAMltWfT
REU:ASE:/TRAHSPORT
DIrG Cont8Ct
~
~ ~-
-I
-'I(
lMdI G8I
EmII8Ion8
~
PI1rn8y RoI88 crI &polen
SeooIIdII'I RoIM8 of &polin
-- lnoon"'" AouIe8 of ExpoIuIw
~=]
. UndII CIIMI8d will dIM fI
AFFECTED
MEDIA
~ SoII8.
lkaurflC8 Sol
8uf1C8 Waterl
8dnenI
EXPOSURE
POINT
EXPOSURE
ROU'TE
PRIMARY
RECEPTOR
Uechate
Ingedan
Tr.....-w
Sb WorbtI/
,... 8118 U...
DInnIII ConI8cI
Off SII8
Tenental WIcII.
IIIocoboenIriII
OnSb
Off SIt8
r-I ktgedan J-} I T~ I
- 8Ite WOffwfII
On Sb ~-1-1 DennII ConI8ct J- FUIIn SIte u...
-I ~~1 1---1 T~ ~--f
~
Nt
IntIIIIIIIon
Tr..,.....,.,
. WOlftMl/
Ftm8 8111 U...
&pIoeJon
Figure 9. Conceptual Site Model for Craig Road Landfill, Fairchild AFR.
SECONDARY
RECEPTOR
ConNnen of
WIldlife
-------
the CRL site. Exposure routes associated with groundwater include ingestion, inhalation, and
dermal contact with groundwater contaminants. Risks associated with a residential groundwater
exposure scenario were estimated in the Baseline Risk Assessment. The groundwater exposure
scenarios are summarized in Table S.
-
::
The current and expected future groundwater use in the immediate vicinity of the site is
residential and light industrial. There are currently four residential drinking water supply wells
located within one-half mile of the site. Three of these wells are not currently used for
residential use because levels of TCE in these wells exceed federal drinking water standards.
Residential groundwater use is considered the most conservative groundwater exposure scenario
for the site. .
The risk estimates provided in the risk assessment are for exposure to contaminants found in the
Basalt A aquifer. TCE was detected at a level below the federal MCL in the Basalt B aquifer
during the most recent groundwater sampling round. Figure 6 shows the general relationship
between the Basalt A and Basalt B aquifers.
Surface and Subsurface Soil
Excavation within the fill areas could result in direct contact with contaminated subsurface soil
and fill material. Several volatile organic chemicals were detected in soil-gas measurements
taken from these areas. Subsurface soil samples were not collected during the remedial
investigation and therefore, risks associated with this exposure pathway have not been quantified.
Soil-gas measurements are indicative of soil contamination; exposure to subsurface soils could
result in unacceptable risks to human health.
Historical aerial photographs and field test pits indicate that a native soil cover was placed over
the subsurface disposal areas. Therefore, surface soil contamination is not. suspected at the site
and is not considered a complete contaminant exposure pathway.
Surface Water/Sediments
Surface water associated with the wastewater treatment plant and surface runoff due to
precipitation infiltrates to groundwater on site. Surface water and sediments associated with the
WWTP pond do not contact contaminated fill materials. Therefore, contamination of surface
water and sediments is not suspected at the site and is not considered a complete contaminant
exposure pathway.
Air/Landnn Gase;
Emissions of volatile organic contaminants from the fill areas to the atmosphere is a potential
route of contaminant migration. Methane gas, generated under anaerobic conditions within the
landfill, can act to enhance migration of volatile contaminants through the air pathway.
Inhalation of air contaminants by nearby residents and workers is a potential exposure pathway.
An air pathway analysis was performed by EPA Region 10 to estimate risks associated with this
FAfBlCRUROD . 02101193
-------
Table 5
Human Exposure Scenarios for Risk Assessment
a) Ingestion o' drinking water:
U\I!J3t~!I~.~~~~!I..~~:. UtII"~cif AdJC!!nl!'OAie81... ..~...... ;'..'...~.'.'..~. f.,.~.,.. ..'.' ..~.,..~....r~.: En.. Vlr~~e. n!~tt.4e.. ~. !.~'}
souriiIArH)':,:U}."(. ... '.Qif.+.~.;.~tJ"::...'.;:'::::{{i;:./.:::"", ..,. . 0' COricern. '. '.'. .:..
PAST: Two ar... oliandllil.
Including M/lltarynnduatrlal
waate, conatructlon debrl..
oleln.r. Ind 8O/vent.. pllnt.
and thlnn.r., waate 011..
N
..,J
CURRENT: Dlechlrg. Ind
InllhrltlonllYlporlUon 01
ellluent ,,~ Ba.. wlatlWlt.r
treatment plant. AI.II.
f.noed and poated Q_rnment
PropertylNo Treepl..lng.
However. Infrequent acc...
r.qulr.d by worke,. lor pond
.nd ditch mllntenanc. Ind
weed conlrol.
RME . R.leonlbl. Maximum Expoeur..
UCl . Upper Confidence Umlt.
CURRENT: Within half-mlle
radlu. of Iindflll.llnd u..
1.Iow-d.nllty rurll r.lld.n-
tlal. medlum-den8lly
houllng (mobile home park).
light Induetrlal. and mining
(gravel). Within one-mlle
rldlu. of landfill. land u...
lnolude Igrfouhure. recrel-
lion. rural relldenoe..
oomm.roaand Induatry. Agrl-
cuhure Inolude.lrrlgat.d
orop. and oattle.
Ingeatlon 01 drink-
Ing wlter from locil
011-.11. well..
Groundwlter: locil
alluvia' and bedrock
aquifere.
. ,
'. ~arTIpie ~! Expoll~re
E;XP~re ModelA8lUmplion. (f'e8ldentlal Scenario)
Average
Expo.ure Factor AME C8IIe
UII of groundwater.. I Chemical Concentrallon 85% UCl Mean
drinking water .upply. In Groundwater (pall) 01 mean Value
Currenlly. four drinking water Inge8llon 01 Water (Uday) 1/ 1.4
IUpply well. exlat wllhln one-
half mile 01 lite. Only one Expo.ure Frequenoy (daya/yr) 3SO 274
In current UII. Eatlmated that
15-20 exlat within one mile 01 Expo.ure Duration (yeara) 30 8
8lte.
-------
Table 5 (Continued)
Human Exposure Scenarios for Risk Assessment
b) Inhalation Of organic vapors from drinking waler:
~7:MfJcn!~0~0}
..... 6ii._~~,!,~.:a00.'::.'.:;~~~~Pt~r~... ~=r;nlllr.tt41..,.
PAST: Two Ireilif Ilndn".
Including IInltarynndultrlll
walle. conetrucllon debrll.
olune" and 8O/ventl, palntl
Ind thlnnerl, WI.' 0111.
N
00
CURRENT: DIICharge and
Innltrltlon/evaporatlon 01
effluent trom B..e wa.ewlter
t"ltment pllnt. Arel II
fenoed Ind polled GCMlrnment
PropertylNo Treapa..lng.
HOWIYIr, Infrequent acee..
required by workere for pond
and dltoh malntenano. and
w..d oontrol.
CURRENT: Within hllf-mlle
radlul of Iindn", Iind u..
II low-dent/tr rural "alden-
1111, medlum-denalty
houtlng (mob"e home plt1l).
light Indullrill. and mining
(Gravel). Within one-mile
radlul of landn", land U"I
lneludl a"rloulture. rlOr.l-
tlon, rural "t/dene...
commerce and Induttry. Agri-
culture Includ'llrrlglled
cropl and cattl..
Inhalation 01
or"lnlc vaporl
In wen water.
Atmolphere: breathing
zone In bath or
thawer .
..'... ~'11p1It)j~~!"
...'."'.. ., .. ..'.".:>.." :
Breathing vaporl emanalln"
from drinking water during
Ihower or bath.
~re Modll Allumptlon. (~"d.nll.1 Settlarlo)
Expo.ute Factor
Chemical Concentration
In Oroundwater (POlL)
Contact Rate for
Inhalillon (m3lday)
Expo.ute Frequency (dayalyr)
Expolure Durellon (yel")
Adult Bod)' Weight (kg)
Air Concentrallon Flctor
from Domallic Water U..
(Um3)
Average
AME Ca88
85% UCL Mean
01 mean Value
16 15
350 274
30 II
70 70
0.6 0.6
I ~o <:;' I J
,
-------
Table 5 (Continued)
Human Exposure Scenarios for Risk Assessment
c) Dermal contact with drinking water:
~g!rf!1I~,'l~,""::Land.:,:,::,:::,,:.:,..',:.':.::.':::':::..::::.,;,~;",;::,!:"!..,:.,~:,,eI.:":':,::::":,'.,'~.':::,,,..':",::::,~,.:.:,::.,.':~ilOO:~Ai;ljoIl)'iiG N."'-;{:~!,,:~:~~W!:, O~fn~~~m'ntaI,':,'.:," ~~~Ii.",""",..
............... oil~:~~~:;:J:)::.::.:::::::..:.... '''. ""'....,
PAST: Two areal U land nil,
Including ..nltaryllndUllrlal
waite, conltrucllon debrll,
cleanerl Ind IOIventl, palntl
and thlnnerl, Wlltl 0111,
N
\0
CURRENT: DllCharge and
Innltratlon/evaporatlon 0'
emuent from Ba.. wall-ater
lrellment plant. "'Iall
'enced and polled Government
Property/No TrI'Pliling.
However, Infrequent acc...
required by work." for pond
and ditch malntlnanol and
_Id controt.
CURRENT: Within hall-mll.
radlul o"andnll,'and u..
Illow-dlnllly rural ralld,n-
1111, medlum-dlnllty
hauling (moblll homl park),
light IndUllrlal, and mining
(grawl). Within _lie
radlul o'landnll, land u..,
Include agriculture, r8Crel~
lion, rural rllidencII,
commerce and Indullry. Agrl-
culturlincludlllrrlgited
cropl and canle.
Dermal contact with
well wlter.
: ~m~p'~~ur.',
. ....
.....
..,
Groundwater: Ba..11 Flow U.. o'groundwlter 'or
A Aquller, ehower!nglbe!h!n;.
"
~t~",~,,~'~~.uinpUOn' (",lIdlmlll Sc,narlo)
Average
Expolure Factor RME CaM
Chemical Concentrillon 86% UCl Mean
In Groundwller (pgll) 0' mean Value
Skin Surlace "'ea 20000 20000
'or Adult (cm2)
ExpOlure Time (houraldly) 0.17 0.12
Exp01ure Frequency (dayalyr) 350 274
Expo1ure Durallon (yea181 30 8
-------
pathway. EPA's SCREEN air dispersion model and soil-gas measurements from the two fill
areas at the site were used to support the risk calculations.
An additional hazard posed by migrating methane gas is the potential for explosion due to
gaseous buildup in confined spaces. Such buildup normally occurs through penetrations and
cracks in the foundation. The nearest buildings in the vicinity of the site are located
approximately 650 feet from the site boundary. These buildings are mobile homes and do not
have basements; the likelihood that methane will accumulate under these well ventilated
circumstances is small. Even with skirting, unless the skirting intercepts the gas flow and traps
the gas, the hazard should be low. Since the quantity of methane generation at the landfill is
uncertain, the remedial actions developed for the site have been developed to address landfill gas
generation.
l'
<;;
./
b. Exposure Point Concentrations
Groundwater Contaminants. Average and reasonable maximum exposure (RME) .point
concentrations were developed for TCE, 1,I-DCE, vinyl chloride, and BEHP based on actual
measurements made during the RI investigation. Analytical data used for determining the
exposure point concentrations were obtained from monitoring wells containing the peak
concentrations of each of the contaminants. For example, MW-85 contained the peak
concentrations of TC£; therefore, temporal data from this well was used to calculate .the
exposure point concentration for TCE. The 95 percent upper confidence limit on the mean was
used to calculate RME exposure point concentrations. One-half of the detection limit was used
to calculate the exposure point concentrations in the case where a contaminant was not detected
in a sample. Exposure point concentrations for vinyl chloride, I, I-DCE, TCE, and BEHP were
derived from data collected from monitoring wells MW-18, MW-69, MW-85, and MW-69,
respectively.
The calculated 95 percent upper confidence limit was higher than the peak concentration for all
of the contaminants evaluated in the risk assessment; therefore, in accordance with RAGS
HHEM, the maximum concentration was used in computing the risk estimates.
Air Contaminants. The following worst-case emissions rates (measure in ug/s) were estimated
using EPA's Farmer model, AirlSqperfund National Technical Guidance Study Series. Volume
2. Estimates of Baseline Air Emissions at Superfund Sites (1990).
~
Benzene
Methylene Chloride
EE
NE
SW
0.109
1630
2.60
11500
448
870
The worst-case emission rates were used in conjunction with EPA's SCREEN air quality
dispersion model to estimate the ambient concentrations of air pollutants at various off-site
locations surrounding the landfill, including at a mobile home park located approximately 650
feet from the CRL site boundary. The worst-case, I-hour concentrations for benzene, methylene
chloride, and TCE at the mobile home park were 0.98, 1.97, and 1.94 ugtm3, respectively.
FAfBlCRUROD - 02101/93
-------
c. Exposure Factors
Exposure factors used to derive chemical uptake for the groundwater and air exposure pathways
were obtained from EPA's Standard Default Exposure Factors document (OSWER Directive No.
9285.6-03). For each contaminant, the average case (using mean concentration) and RME (95 %
UCL) risks were calculated using the exposure model assumptions presented in Table 5. The
exposure factors used to derive contaminant uptake from groundwater through dermal contact
during showering and bathing were obtained from EPA's "Interim Guidance for Dermal
Exposure Assessment" and the Risk Assessment Guidance for Suoerfund. Volume I: Human
Health Evaluation Manual (RAGS HHEM).
3. Toxicity Assessment
Toxicity information was provided in the Baseline Risk Assessment for the chemicals of concern.
Generally, cancer risks are calculated using toxicity factors known as slope factors, while
noncancer effects rely on reference doses.
Slope factors (SFs) have been developed by EPA for estimating excess lifetime cancer risks
associated with exposure to potential carcinogens. SFs are expressed in units of (mg/kg-dayr1
and are multiplied by the estImated intake of a potential carcinogen, in mglkg-day, to provide
an upper-bound estimate of the excess lifetime cancer risk associated with exposure at that intake
level. The term "upper bound" reflects the conservative estimate of the risks calculated from
the SF. Use of this approach makes underestimates of the actual cancer risk highly unlikely.
SFs are derived from the results of human epidemiological studies, ,or chronic animal bioassay
data, to which mathematical extrapolation from high to low dose, and from animal to human
dose, have been applied.
Reference doses (RIDs) have been developed by EPA for indicating the potential for adverse
health effects from exposure to chemicals exhibiting noncarcinogenic effects. RIDs, which are
expressed in units of mglkg-day, are estimates of lifetime daily exposure for humans including
sensitive subpopulations, that are likely to be without risk of adverse effect. Estimated intakes
of contaminants of concern from environmental media (e.g., the amount of a contaminant of
concern ingested from contaminated drinking water) can be compared to the RID. RIDs are
derived from human epidemiological studies or animal studies to which uncertainty factors have
been applied.
The Baseline Risk Assessment relied on oral and inhalation Sfs and RIDs. Because dermal
toxicity factors have not been developed for the chemicals evaluated, oral toxicity factors were
used in estimating risks from dermal exposure. The toxicity factors shown in Table 6 were
drawn from the Integrated Risk Infonnation System (IRIS) or, if not IRIS values were available,
from the Health Effects Sumnwy Tables (HEAST).
Tricbloroetbene
According to the most recent assessment of TCE on the IRIS database, the chronic oral and
inhalation RID assessments are under review by an EP A work group. The most recent annual
FAFBICRlJROD.02IOI/93
-------
Table 6. Toxicity Factors for Chemicals 0' Concern
Chronic Reference Dose Slope Factor Weight 0'
(mg/kg-day) 1/(mg/kg-day) Evidence
Analvte Inhalation Oral Dermal Inhalation Oral Dermal Class
Trlchloroethene 1.7E-02 (a) 1.1E-02 (a) 1.0E-02 (b) 82
1 ,1-Dlchloroethene 9.0E-03 (c) 9.0E-03 (b) 1.2 (a) 6.0E-01 (c) 6.0E-1 (b) C
Vinyl chloride 2.9E-01 (a) 1.9 (a) A
VJ bls(2-ethylhexyl)- 2.0E-02 (c) 1.0E-03 (b) 1.4E-02 (c) 2.8E-01 (b) 82
N
phthalate
Sources:
(a) EPA Health Effects Assessment Summary Tables (HEAST), 1991.
(b) EPA Interim Guidance for Dermal Exposure Assessment, 1991.
(c) EPA Integrated Risk Information System (IRIS), on-line database.
. "
'" '
-------
summary (FY-1991) of HEAST reports TCE as a Group B2 carcinogen (probable human
carcinogen). An inhalation slope factor of 1. 7)(10-2 (mglkg/day)"l was reported based on two
inhalation studies using mice. An oral slope factor of 1. IX 10-2 (mg/kg/dayr1 was reported
based on two studies on mice where tumors developed on livers. Although both slope factors
had been removed from IRIS pending further review, the slope factors for inhalation and oral
ingestion presented in HEAST were used in this risk assessment.
4. Risk Characterization
For carcinogens, risks are estimated as the incremental probability of an individual developing
cancer over a lifetime as a result of exposure to the carcinogen. Excess lifetime cancer risk is
calculated by multiplying the SF (see toxicity assessment above) by the "chronic daily intake"
developed using the exposure assumptions. These risk are probabilities generally expressed in
scientific notation (e.g., 1 x 1~. An excess lifetime cancer of 1 x 10-6 indicates that an
individual has a I in 1,000,000 chance of developing cancer as a result of site-related exposure
to a carcinogen under the specific exposure conditions assumed.
The potential for noncarcinogenic effects is evaluated by comparing an exposure level over a
specified time period (e.g., lifetime) with a reference dose (see toxicity assessment above)
derived for a similar exposure period. The ratio of exposure to toxicity is called a hazard
quotient. Hazard quotients are calculated by dividing the chronic daily intake (CDI) by the
specific RID. By adding the hazard quotients for all contaminants of concern that affect the
same target organ (e.g., liver), the ha23J'd index (HI) can be generated.
Groundwater Pathway
The cancer risk estimates associated with groundwater exposure are summarized in Table 7.
The total excess cancer risk for reasonable maximum exposures to groundwater is Ix 10-3. This
risk level exceeds the EPA Superfund acceptable risk range of 1 x 1()'4 to 1 x 1~ (1 in 10,000
to 1 in 1,000,(00).
Comparing the risk contribution from each contaminant shown in Table 7, the total excess
cancer risk associated with TCE is two orders of magnitude higher than the risk associated with
the other individual contaminants. The summary of carcinogenic risks in Table 7 indicates that
the inhalation exposure route creates a greater risk to human health than the ingestion exposure
route. This is due to the relatively higher inhalation slope factor for 1, I-DCE and TCE when
compared to' their oral slope factor. .
Table 8 presents the estimates of noncarcinogenic toxic effects (RME) calculated for chronic
exposure to 1,1- DCE and BEHP in groundwater. For the ingestion of drinking water route of
exposure, the hazard quotient for l,l-DCE is 0.002; for BEHP, 0.07. For dermal contact with
groundwater during showering and bathing, the hazard quotient for 1,t-DeE is 0.00004; for
BEHP, 0.00001. The total sum of chronic noncarcinogenic estimates via the groundwater
pathway is 0.07, which is the same approximate magnitude as associated with the ingestion of
BEHP in drinking water. The estimates for noncarcinogenic health effects are below unity,
indicating that adverse health effects would not be expected under the defined exposure scenario.
FAFBICRlJROD . 02101/93
-------
Table 7. RME Cancer Risk Estimates
CRl, Fairchild AFB, W A
Exposure Route: Ingestion of Drinking Water and Inhalation of Vapors During Household Use (VOCs only)
RiskRMI! = C x [(CCRoxEFxD)xSF J + (CACxCRjxEFxD)xSFj>J
BWxAT BWxAT
where: C = Concentration; peak value used, 95% VCl exceeds peak; (ug/lxO.OOI mg/ug)
CRo Contact rate for ingestion (Llday)
CRj = Contact rate for inhalation (m)/day)
EF = Exposure frequency (days/year)
D Duration (years)
BW Body weight (kg)
AT = Averaging time (years x days/yr)
AC Air concentration factors resulting from domestic water use (Urn)
SFo Oral slope factor (mglkg-day)"1 (HEAST)
IJ.) SF; Inhalation slope factor (mg/kg-day)"1 (HEAST)
,po
Chemical Group £ £Ro. CR. ill: Q BW AT M:: m:o SF. Risk
-I -I
Vinyl chloride A 2 2 15 350 30 70 70x365 0.5 1.9 2.9x 10-1 (a) 7x IO-s
1,I-DCE C 0.8 2 15 350 30 70 70x365 0.5 6xlO" 1.2 4x IO-s
TCE B2 2800 2 15' 350 30 70 70x365 0.5 I. Ix 10-2 I.7x 1O.2xO.35 (b) IxlO')
BEHP 82 53 2 NA 350 30 70 70x365 NA 1.4x 10,2 NA 9x 10-6
(a)
(b)
SPj not available in HEAST value derived using unit risk. See calculations in Appendix B for conversion calculations.
The inhalation slope factor for TCE is for absorbed or metabolized dose; therefore, calculations or risk include an absorption correction of 0.35 for
the inhalation slope factor.
Not applicable; semivolatile chemical, dQe$ not affect inhalation exposure route.
NA
'" .
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Table 7. RME Cancer Risk Estimates
CRL, Fairchild AFB, W A (conI.)
Exposure Roule: Dennal Contact with Groundwaler During Showering/Bathing
RiskRMI! = (CW x SA x I
-------
Table 7. RME Cancer Risk Estimates
CRL, Fairchild AFB, W A (cont.)
Summar, or Carcino2enic Risk CRME):
Chemical of Concern
Exposure Vinyl Total Risk
Route chloride LI-DCE TCE BEHP via Route
Ingestion of 4x 10-s 6xlO-7 4x 10-4 9xlo.6 4x 10.4
groundwater
Inhalation of 3xlO-s 4xlO-s 7x 10.4 NA 8x 10-4
VOCs
Dermal contact NA 9x 10-8 5x IO-S 2x 10-9 5x 10.5
Total risk via
l.J groundwater 7xlO-s 4xlO-s Ix 10-3 9x 10-6 I X 10-3
0\
pathway
-------
"
Table 8. RME Chronic Noncarcinogenic Effects Estimates,
CRL, Fairchild AFB, W A
EXDosure Route: Ingestion of Drinking Water
HIRME = C x fCR x EF X D)/RIDo
BW x AT
where: C = Concentration; peak value used, 95% VCL exceuls peak; (ug/LxO.OOI mg/ug)
CR Contacl rale for ingestion (Llday)
EF Exposure frequency (days/yr)
D = Duration (years)
BW Body weight (kg)
AT Averaging time (yrs x days/yr)
RIDo = Oral reference dose (mg/kg-day) (HEAST)
Chemical ~ CR m: Q BW AT RIDo HI
VJ
...... I,I-DCE 0.8 2 3S0 30 70 30x365 9x 10-3 2x10-3
BEHP S3 2 350 30 70 30x365 2x 10-2 7x 10-2
-------
Table 8. RME Chronic Noncarcinogenic Effects Estimates,
CRL, Fairchild AFB, W A (cont.)
Exposure Route: Dennal Contact with Groundwater During Showering/Bathing
HQRMI! = CW X SA x K" x ET x EF x ED x CF/RfDd
BW x AT
where: CW Chemical concentration in groundwater (ug/LxO.OOI mg/ug)
SA Skin surface area available for contact (cm2)
~f Chemical-specific dermal permeability constant (em/hr)
= Exposure time (hours/day)
EF Exposure frequency (days/yr)
ED Exposure duration (years)
CF Volumetric conversion factor for water (I LIIOOO cm3)
BW = Body weight (kg)
UJ AT Averaging time (yrs x days/yr)
00 RfDd Estimated dermal reference dose (mg/kg-day)
Chemical CW SA K., ET EF ED CF BW AT RfDd HQ
I,I-DCE 0.8 20000 9.551. 10-3 0.17 350 30 0.001 70 30x365 91. 1O'3(a) 4JllO's
BEHP 53 20000 5.701.10-6 0.17 350 30 0.001 70 30x365 Ix 1O'3(b) IxlO's
(a)
DCE is small organic molecule with properties similar to lipid-soluble anesthetics; thus, it is expected to readily penetrate skin, which is lipid-rich tissue
(similar to TCE). Calculation of dermal slope factor assumes complete absorption.
Toxicokinetic study reports absorption rate for BEHP of 5 %.
(b)
-------
,c
Table 8. RME Chronic Noncarcinogenic Effects Estimates,
CRL. Fairchild AFB, W A (cont.)
Summary of RME Chronic NoncarcinOl!enic ElTecl~:
Exposure Chemical of Concern Total Risk
Route I.I-DCE BEHP via Route
Ingestion of Groundwater 2x 100] 7x 10-2 7xlO-2
Dermal Contact w/Groundwater 4x 1005 Ix 10-5 5xlO-.s
Total Chronic Effects via
Groundwater Pathway - HI . 2x 10-3 7xlO-2 7xlO-2
IoN
-------
Air Pathway
Cancer risk estimates for the air exposure pathway are shown in Table 9. Risk estimates
associated with the three contaminants of concern under a residential exposure scenario for five
off-site locations are shown. Total risk is the sum of the risks from exposure to all three
contaminants from both landfill areas.
u
.-
Factors that may underestimate risks to future residents are: (1) gas-generation within the
landfill was not considered; (2) air-filled porosity was not directly measured but was estimated
based on the soil's water capacity; and (3) soil-gas samples were not analyzed for vinyl chloride,
a common landfill constituent. The presence of vinyl chloride could increase. risks associated
with this pathway. In addition, many factors will change over time, such as soil-gas
concentrations. Any increase or decrease in soil-gas concentrations will be reflected as increases
or decreases in risk rates.
The risks from exposure to annual air concentrations, which are more appropriately used for risk
assessment calculations, are expected to be at least an order of magnitude less than the risks
from the I-hour, worst-case concentrations presented here. The following factors lead to
overestimation of actual risk: (1) the highest values of soil-gas concentrations were used, (2)
the area over which flux occurs was conservatively estimated, (3) the worst possible atmospheric
conditions were used in the air model, and (4) worst-case, I-hour concentration was assumed,
rather than one-tenth the worst-case, I-hour concentrations, which is more commonly used.
These calculations lead to worst-case estimates of emissions, ambient concentrations, and
carcinogenic risks.
Table 9. Estimated Maximum Carcinogeaic Risks at Given LocatioDS
Mobile Boundary Location
Compound Home Park North West South East
Benzene 7 x 10-6 2 x lO-s 1 x 10-4 9 x l(rs 4 x lO-s
Methylene Chloride 4 x ur7 1 x 10-6 5 x 10-6 4 x 10-6 3 x 1
-------
,"
Uncertainty in the toxicity evaluation may overestimate risk by relYing on slope factors that
describe the upper confidence limit on cancer risk for carcinogens. Some under estimation of
risk may occur due to lack of quantitative toxicity information for some contaminants detected
at the site. Qualitative uncertainty exists in evaluating carcinogenicity of chemicals that have
no human evidence of carcinogenicity. Evidence for carcinogenicity of TCE is based on animal
studies, and weight of the evidence for TCE is under review by EPA to determine status as
either B2, probable human carcinogen, or C, possible human carcinogen.
Another uncertainty arises as to whether groundwater detections of vinyl chloride, I, I-DCE and
BEHP are actually associated with the site. Each of these contaminants.has a very low
frequency of detection. Since vinyl chloride and I,l-DCE were infrequently detected, RAGs
were not set for these compounds. However, because they are breakdown products of TCE,
they should be included as part of the long-term monitoring. Since BEHP was detected in
groundwater at a low frequency and since the detections may be associated with field or
laboratory contamination, BEHP is not considered in the Remedial Action Objectives for
remediation.
B. Ecological Risk Assessment
To assess the environmental effects of the contaminants present at the CRL site, an evaluation
of potentially affected terres1rial species was conducted. Three sta~esignated species
(burrowing owl, great blue heron, and Swainson' s hawk) have been observed on the Base and
may inhabit or frequent the CRL. No federal or state threatened or endangered species are
known to occur at the CRL. A site-specific survey of the number and species of animals
inhabiting the landfill area was not conducted as part of the remedial investigation.
The primary exposure routes available to wildlife at the CRL site are inhalation of volatile
organics associated with soil-gas and ambient air at the site and dennal contact with
contaminated subsurface soils and fill material, particularly for burrowing and underground
dwelling wildlife. Contaminants detected in soil-gas measurements were selected as the
contaminants of concern for ecological exposure through the air pathway. Ecological exposure
to subsurface soil contamination was not evaluated since the level of soil contamination was not
~uantified during the investigation.
Exposure to surface water and sediments associated with the wastewater treatment plant
infiltration pond were not considered a complete contaminant pathway since surface water and
sediment contamination are not suspected at the site. Contaminated groundwater is not in
contact with surface water and therefore was not considered a complete exposure pathway.
Due to the lack of actual ecological site data and toxicological data on wildlife, toxicity
thresholds developed for laboratory animals were in the ecological assessment. Table 10
provides a comparison of mean and maximum subsurface soil-gas concentrations of TCE,
benzene, toluene, total xylenes, and methylene chloride detected during the remedial
investigation with the toxicity thresholds developed for mice. The comparisons shown in Table
10 indicate that burrowing animals inhabiting the landfill could potentially be impacted by the
contaminant vapors present in the soil pore spaces.
-FAfBlCRUROD - 02101/93
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Table 10
RISK CHARACTERIZATION FOR THREE CONTAMINANTS OF ECOLOGICAL CONCERN
FOR FAIRCHILD AFB
MEAN MAXIMUM
TOXIC THRESHOLD (1) SUBSURFACE SOIL-GAS (3) SUBSURFACE SOIL-GAS (3)
CONCENTRATIONS (ppm) CONCENTRATIONS (ppm) CONCENTRATIONS (ppm)
TCE 8450 (2) 1500 96000
Benzene 100 240 18000
Toluene 1200 1300 130000
.I:-
N
TOlal Xylenes 5300 3200 460000
Melhylene Chloride 100 460 4700
(1) U.S. Depanment of Health ATSDR (Chronic toxicity threshold Inhalation values for mice).
(2) U.S. Depanmenl of Heallh A TSDR (Aculeloxlclly Ihreshold Inhalation values for mice).
(3) Soli-Gas Survey by SAIC - Values represent the worst-case concentrations Sampled al a 3-foOI depth on the average.
" '
-------
"
Uncertainties in evaluating the effects of ecological exposure to chemical contaminants at the
CRL include: (1) lack of site-specific ecological survey for the CRL site, (2) limited
toxicological data, and (3) uncertainties in ecological exposure factors.
VD. REMEDIAL ACTION OBJECTIVES
Remedial action at this site its required to protect human health and the environment. The
following findings of the remedial investigation and baseline risk assessment support the need
for cleanup action at the site:
.
TCE have been detected in groundwater samples from residential wells and on-
site and off-site monitoring wells at concentrations exceeding federal maximum
contaminant levels. The affected aquifer serves as a water source for both
residential and municipal water supplies.
.
The excess cancer risllc associated with the reasonable maximum groundwater
exposure is estimated to be I in 1000. This exceeds the EPA acceptable risk
range of 1. in 10,000 to 1 in 1,000,000.
.
Two fill areas at the landfill continue to be a source of a groundwater
contamination plume.
.
Soil-gas measurements indicate that volatile contaminants are present within the
fill material. Although the risks have not been quantified, direct exposure to
subsurface soil and debris may result in unacceptable risks.
Remedial Action Objectives (RAOs) for the CRL were developed to address the requirements
of CERCLA, as amended by SARA, and the state of Washington's Model Toxics Control Act
(MTCA). The RAas for the CRL were developed in acCordance with the National Contingency
Plan (NCP) to protect human health, public welfare, and the environment from potential threats
due to contaminants associated with the site. The specific goals and objectives of the remedial
action at the CRL are:
1.
To prevent consumption by area residents of groundwater exceeding federal MCLs
2.
To restore contaminated groundwater in the upper aquifer to levels that are safe for
drinking
3.
To prevent further migJ-atton of contaminated groundwater across the site boundary and
to the lower aquifer .
4.
To minimize the migration of contaminants from the fill material to the groundwater
5.
To prevent exposure to contaminants within subsurface soil and debris.
FAFBICRUROD . 02101/93
-------
Groundwater cleanup levels have been established to meet the requirements of CERCLA, and
MTCA as an applicable requirement. MTCA Method B, which is the standard method for
complex sites such as the CRL, was used to establish cleanup levels. The Method B cleanup
levels are based on MTCA as promulgated on January 28, 1991. The cleanup leyel for TCE
is 5 ug/L. In addition, the cumulative excess cancer risk associated with the site will be reduced
to at most 10-5, consistent with MTCA.
"
-
.0
VIII. DESCRlPfION OF ALTERNATIVES
The cleanup alternatives which were evaluated in the FS include elements frOm two different
categories of actions. The first category is source controls, which are intended to minimize
migration of contaminants from the fill material to the groundwater and to prevent direct
exposure to contaminated subsurface soil and debris. The second action category is groundwater
controls. These controls are intended to prevent further migration of contaminated groundwater
across the site boundary and to prevent consumption by area residents of groundwater exceeding
MCLs. The combination of both source control and groundwater control actions is necessary
to achieve the broader objective of restoring contaminated groundwater in the aquifer to levels
that are safe for drinking.
As pan of the Base's operational plans, the wastewater treatment plant has undergone closure.
This action was taken independently of site remediation efforts; however, several aspects of this
action are expected to facilitate the groundwater cleanup. The closure should reduce the
migration of contaminants from the fill material to groundwater. In addition, the loss of
recharge will lower the gradient of groundwater and reduce the velocity of contaminant
migration.
A. Source Controls
Source control alternatives were developed to address. RAOs 2, 4, and 5. All of the source
control alternatives, except the no-action alternative (SC-l), include institutional controls.
Restricted access to the site (e.g., fences) and posted warnings around the perimeter of the site
would decrease inadvertent contact with contaminated soil and debris. Public meetings and
prepared news releases would allow a wider dissemination and understanding of infonnation on
the health risks of contact with the contaminated soils and debris. Finally, deed restrictions
would be used to preclude future residential, industrial, commercial, or agricultural use of the
area. .
1. Alternative SC-l
The first alternative is no action. Evaluation of this alternative is required under CERCLA; it
serves as a reference against which other alternatives can be compared. Under this alternative,
no action would be taken to control migration of contaminants from the fill material to
groundwater and no institutional controls would be established to prevent exposure to
contaminated subsurface soils and debris. The northeast and southwest disposal areas would
continue to act as a source of contamination to groundwater and groundwater levels would
FAF8ICIUJR.OD . 02101/93
-------
continue to exceed MCLs. Modeling predicts that groundwater contaminant concentrations
would decrease through natural dilution, degradation, and dispersion, and would attain the
cleanup levels in approximately 77 years. There is no cost associated with this alternative.
2. Alternative SC-2
Alternative SC-2 involves containment of contaminants within the landfill. The CRL would be
graded to improve drainage and decrease erosion. A low-permeability cap would be constructed
over the northeast and southwest areas of the CRL. A passive gas management system would
be installed to reduce methane buildup and pressure under the cap. The cap would decrease
infiltration of precipitation through, and contaminant migration out of, the fill areas.
The design, construction, and maintenance of the cap would meet the closure requirements of
Washington State's Minimum Functional Standards for Solid Waste Handling and of federal
RCRA Subtitle D. Emissions from the passive gas management system would be treated as
necessary to ensure compliance with air quality standards set by the state of Washington and the
Spokane County Air Pollution Control Authority, and the Clean Air Act.
Estimated capital cost for this alternative range from $3,772,325 to $4,222,325. Operating and
maintenance costs for the alternative range from $34,184 to $37,000 per year. The estimated
present net worth ranges from $4,297,817 to $4,791,106, assuming a 5 percent discount rate and
30 years of O&M costs.
3. Alternative SC-3
This alternative would include all of the actions described in Alternative SC-2 (a cap and passive
gas management system) with the addition of hot spot removal prior to the construction of the
landfill cap. The goal of hot spot removal is to remove highly contaminated material from the
landfill to reduce the potential for continued groundwater contamination. Hot spots would be
identified based on the results of soil-gas measurements taken during the remedial investigation.
Intact containers of contaminaJ!1ts and contaminated material surrounding ruptured containers
would be removed, placed in sealed containers, and shipped for proper off-site
treatment/disposal. Figure 6 shows the hot spots identified in the RI Report. An estimated total
of 300 cubic yards of material would need to be removed at the CRL, assuming there are only
five hot spots in the landfill and that 60 cubic yards of material would need to be removed per
hot spot. Excavation, transport, and treatment/disposal of the contaminated material would
comply with the RCRA Subtitle C regulations.
The costs for this alternative are estimated at $4,237,525 to $4,687,525 (capital cost); $34,184
to $37,000 (O&M costs); and $4,297,817 to $4,791,106 (present net worth), assuming a 5
percent discount rate and 30 years O&M costs.
4. Alternative SC-4
Alternative SC-4 includes the landfill capping component from Alternative SC-2 with the
addition of an active soil vapor extraction system. The extraction system would include the use
FAfBlCRUROD.02IOI/93
-------
of vacuum blowers, air infiltration and vapor extraction wells, collection headers, and treatment
systems. A treatability study would be performed to detennine the optimum gas extraction and
treatment system design. The emissions from the vapor treatment system would comply with
the Spokane County Air Pollution Control Authority and state of Washington air quality
standards, and the Clean Air Act.
Estimated costs for the alternative are $4,581,875 to $5,031,875 (capital costs), $45,684 to
$48,500 (O&M costs), and $5,284,150 to $5,m,439 (present net worth), assuming a 5 percent
discount rate and 30 year O&M.
B. Groundwater Extraction and Treatment
Groundwater alternatives were developed to address RAOs 1, 2, and 3. All of the alternatives
include monitoring the groundwater near the CRL. Institutional controls and public education
and notification would be included as part of all of the alternatives except for the no-action
alternative (GW-l). Institutional controls can. be implemented to discourage access to
contaminated groundwater. Deep wells that are located within the contaminant plume may
provide a conduit for contaminant migration to lower aquifers. These wells would be inspected
and reconstructed or abandoned as necessary. Public education and notification would include
public meetings, prepared news releases, and information provided to groundwater users as a
method for disseminating information about the contamination and associated risks.
1. Alternative GW-l
The first alternative is no action. Evaluation of this alternative is required under CERCLA; it
serves as a reference against which other alternatives can be compared. Under this alternative,
no action would be taken to treat or contain contaminated groundwater and no institutional
controls would be imposed to prevent use of contaminated groundwater. Contaminants at levels
exceeding MCLs would continue to migrate toward residential and municipal drinking water
supply wells. Modeling predicts that groundwater contaminant concentrations would decrease
through natural dilution, degradation, and dispersion, and would attain the cleanup levels in
approximately 77 years. Groundwater monitoring would allow a periodic assessment. of the
migration of the contaminant plume. The public would be informed of the results of the
monitoring program.
Although there would be no capital cost, periodic monitoring over a 3O-year period would incur
annual O&M costs of $40,000. The present net worth of this alternative would be $614,898.
2. Alternative GW-2
This alternative involves the installation of a groundwater extraction and treatment system on
the CRL property. The objective of this alternative is to prevent continued migration of
contaminated groundwater from the CRL site. To accomplish this, a total of approximately 20
extraction wells would be installed along the north and east boundaries of the northeast disposal
area and along the east boundary of the southwest disposal area. Groundwater would be
extracted from the upper aquifer and treated using an air stripping unit. Air stripping would
FAFBICRUROD - 02101193
-------
reduce the concentrations of contaminants in the extracted water to the groundwater cleanup
levels established for the site. The treated water would be reintroduced into the upper aquifer
at an off-site location downgradient of the CRL. Groundwater monitoring wells would be
installed to monitor effectiveness of the extraction system.
The air emissions from the air stripper would be treated using activated carbon. Used carbon
would be recycled off site at an EPA-approved facility. Air emissions from the air stripper
system would be treated as necessary to ensure protection of human health and the environment
and compliance with air quality standards set by the state of Washington and the Spokane County
Air Pollution Control Authority.
Preliminary calculations indicate that the extraction system would capture groundwater within
approximately 40 feet of the disposal area boundaries. The timeframe required to achieve the
groundwater cleanup levels in the upper aquifer within the landfill boundaries ranges from less
than 10 years to more than 75 years, depending on the source control alternative selected.
Contaminated water in the upper aquifer outside of this area would remain untreated, and would
reach the cleanup levels through natural dispersion and dilution. Modeling of the upper aquifer's
characteristics indicates that the groundwater cleanup levels would be achieved outside of the
site boundaries in approximately 6 years. Residential and municipal water supply wells would
be monitored, and water users notified if their water supply contained contaminants in excess
of the MCLs.
The groundwater cleanup levels established for the site would be attained throughout the
contaminated plume beyond the point of compliance, which is defined as the CRL property
boundary .
Residual risk associated with the groundwater cleanup levels is 6 x 10-0. This is considered
protective of human health and the environment. Residual risk associated with the air emissions
following contaminant removal from the GAC is estimated at 5 x 10-0, which is also considered
to be protective of human health and the environment.
Approximate costs of the alternative are $1,447,500 (capital costs), $337,000 (O&M costs), and
$3,138,008 to $6,628,016 (present net worth), assuming a 5 percent discount rate and 6 and 30
years O&M costs.
3. Alternative GW-3
This alternative would include the groundwater extraction system described in Alternative GW-2,
with the addition of providing point-of-use treatment andlor an alternative water supply to users
of wells which are constructed in compliance with state and local regulations, and which are
contaminated above MCLs by the off-site portion of the groundwater plume. The objectives of
this alternative are to prevent continued migration of contaminated groundwater from the CRL
site, and to prevent consumption by area residents of groundwater contaminated above MCLs.
Point-of-use treatment systems are typically installed at the wellhead for wells serving multiple
users, or near the point where piping from an individual user's well enters the user's building.
FAf1IICRLIROD - 02101193
-------
Some routine maintenance and periodic replacement of system components would be necessary.
The selection of point-of-use treatment or provision of an alternative water supply would be
made based on several factors, such as distance to an existing water system, or the amount of
water demand. Once the cleanup levels are achieved outside of the site boundaries, point-of-use
treatment and/or an alternative water supply would no longer be necessary. Residual risks
associated with this alternative are the same as for GW-2.
-
Costs for this alternative are estimated at $1,522,500 (capital costs), $347,000 (O&M costs),
$3,283,765 to $6,856,741 (present net worth), assuming a 5 percent discount rate and 6 and 30
years O&M costs.
:
IX. SUMMARY OF THE COMPARATIVE ANALYSIS OF ALTERNA TIVF.S
This section and Table 11 summarize the relative performance of each of the alternatives with
respect to the nine criteria identified in the NCP. These criteria are categorized into three
groups:
Threshold Criteria
1.
Overall protection of human health and the environment
2.
Compliance with applicable or relevant and appropriate requirements
Primary Balancing Criteria
3.
Long-term effectiveness and pennanence
4.
Reduction of toxicity, mobility, or volume through treatment
5.
Short-term effectiveness
6.
Implementability
7.
Cost
Modifying Criteria
8.
State! support agency acceptance
9.
Community acceptance.
A. Threshold Criteria
The remedial alternatives were first evaluated in relation to the threshold criteria. The threshold
criteria must be met by each alternative in order to be selected.
FAFBICRlIROD . 02101193
-------
"
: '
,"
Table 11. Comparl8on 01 Allernatlve.
.c-
OO
I
>
Crlterla/Altemall... 8C.1 .C.2 8C.3 8C.4 , OW., OW.2 GW-3
1. 0..,.11 prot.ctlon W.uld IlOl .\I.ln RAO. Would mlnl...l.. ...lg..lIon Would ...lnl...I.. ...lg,.II.n .nd W.uld ...Inlml" mlg..lI.n D... nol .\I.ln AAO.. P'ot~tI". o' humin Immediate prollcUon
01 hu....n h..llh .nd 0' be prol..lI.. 01 .nd p....nI ..po"". 10 pr.".nt 'IPO'Ut' 10 and pr.".nt '.poIW' 10 I, not prolloU.. of human h..Uh .ndlhe 01 hum.n h..llh and
thlln"lronmlnt. hu....n he.lth .nd lhe .0nt....lnanl8. .ont.mlne",.. W.uld p,.vld. .onlamln.nt.. Vapo' h..Uh or thl In.lronmant Invlronm.nt. Chi .nvlronm.nt.
8n.lronm.nt. 101l\l"1.rm p,ol..II.n. 1.lnKltlon would proYtdl
Po..lbl. ahort.,.rm protlotlon during 8r8dlng.
..DOaul. during 1.0''''Uoo.
2. Compilino. with Would not ma.t Slat. 0' Would ....., I.ndnll Would m..tlandflll cloaul' Would m..t landRIl oloeur. Would nol .1I.ln Would m..t groundwat., Would m..1 G10UndWI'.'
AAAA.. W..hfngton ,.qulrem.nt.. 010..8 requl..m.nt. requtrement.. ,I, .ml..loo r.qulr.mant. .nd ,Ir cl.anup "and.rd.. ol.anup ".nd.rd.. ol.anup It.nd.rdl.
and ai, .m188l0n "and""'., .nd would ..mplv .ml..lon _.ndarcl..
..and.nI.. with RCRA Subtltl. C 10'
Ir..lm.nl o' .Koaval.d material.
3. Lona.l.rm Would ...uI.ln no Would provld. 10ng.I."" Would provld. high 1...1 01 W.uld provld. high ,...1 01 Not prol.otl_. 0' human Would ..t, hI.vll.. on Would pro.,d. hlgh.et
.ff.cllv.n... and reduction o. ...11. ._11....... - long.t.rm .IIIOUv.n... and long.t.rm .11'011...... ana he.lth. Inet.Uutlonal oontrol.. dag'" of long..arm
p.rmaneno.. prol8DI1on - woutd perm.nano.. .nd would p.rman,no.. .net would .".oll..n....nd
lOCIuI.. long".rm requlr.l0ntl"lrm ma.nten8Ino. requlre'ansl'.rm "'alntlnano. protlotlon.
...alnI.- 0' lhe ollhe I.ndnll..p. o'lh.l.ndnll o.p.
I_nil -.
4. R.duotlon of treatm.nt. Would nol dlore... Woutd IlOl d...... Would d..,...lhe TMV. Would d..,... '''' TMV Would not provld. trlatmlnt, Would proYld, '«'011'1. Would provld. .11.011'1'
moblll'r 8nd "alum. lhe TMV. 10xloliV - voIu..... oil'" .ont_lnont.. '''1'''0'' lharel. no ,eduallon 01 TMV 01 I'" reducUon o' TMV
(TMVI Ih,ough "..,....nt. Would ,""uoo ...obUlI,. r.duolioft a' TMY. oontamlft8nt.. a. ~he oon'amln.nl..
5. Short.t.rm W.uld b. 1"""..II..'n Would pro.ld. high 1...1 Would p,o.ld. . I.w., l.v.1 01 W.uld pro.ld. . high 1...1 Would nol p,o.ld. p,ol..II.n Would p,ovld. . hl8h 1...1 Would p,.vld. lhe
.ft.OUY.M... lhe 8hort ,.,.... .1 p,ol..lIon 'n . ahart protloUon In Ih. 8hort '.rm, 01 p,ol..lI.n In . .hort In Ih. .hort ,.,.... .1 p,o...lIon In lhe .hort g,..I.., p,ol.ollon In
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1. Overall Protection of Human Health and the Environment
This criterion addresses whether each alternative provides adequate protection of human health
and the environment and describes how risks posed through each exposure pathway are
eliminated, reduced, or controlled through treatment, engineering controls, and/or institutional
controls.
-
All of the source control alternatives, except Alternative SC-l (no action), would provide
protection of human health and the environment by minimizing migration of contaminants from
the fill material to groundwater, and by preventing exposure to contaminants iri subsurface soils
and debris within a relatively short period of time (1 to 3 years). Alternatives SC-3 and SC-4
would provide a high degree of long-term protection because they actively remove the
contaminants. Alternative SC-l would not be protective of human health and the environment
since contaminants would continue to migrate to groundwater in concentrations above
groundwater cleanup standards.
Alternatives GW-2 and GW-3 would be protective of human health and the environment, since
active measures are taken to prevent migration of groundwater contaminants from the landfill
area. The point-of-use treatment and alternative water supply elements in Alternative GW-3
would provide a high degree of protection, since they can deliver immediate reduction of risk
to human health. Alternative GW-l would not be protective of human health or the
environment, since contaminated groundwater from the landfill area would continue to contribute
to the off-site plume. .
2. Compliance with ARARs
This criterion addresses whether a remedy will meet all of the applicable or relevant and
appropriate requirements of other federal and state environmental statutes or provides a basis for
an invoking waiver.
Compliance with ARARs will be achieved when a so~ce control and groundwater extraction and
treatment technology are used together. Alternatives SC-2, SC-3, and SC-4 will meet the closure
requirements of Washington's Minimum Functional Standards for Solid Waste Handling, and
RCRA Subtitle D, and air emission standards of both the Spokane County Air Pollution Control
Authority and Washington State. Alternative SC-3 would need to comply with regulations in
RCRA Subtitle C regarding shipment and disposal of hazardous wastes.
Both alternatives GW-2 and GW-3 would meet the state of Washington Model Toxies Control
Act groundwater cleanup levels. Air emissions from the groundwater treatment unit will meet
both the Spokane County Air Pollution Control Authority and Washington State air regulations.
GW-l will not attain MTCA groundwater cleanup levels.
FAFBICRUROD - 02101/93
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B. Primary Balancing Criteria
c
"c
Once an alternative satisfies the threshold criteria, it is evaluated against five primary balancing
criteria.
.:
3. Long-term Effectiveness and Permanence
This criterion refers to expected residual risk and the ability of a remedy to maintain reliable
protection of human health and the environment over time, once cleanup levels have been met.
This criterion includes the consideration of residual risk and the adequacy and reliability of
controls.
Alternatives SC-3 and SC-4 would provide the highest level of long-term effectiveness and
permanence because they provide contaminant removal and ultimate destruction. Long-term
effectiveness of alternatives SC-2, SC-3, and SC-4 would be dependent upon long-term
maintenance of the landfill cap. Alternative SC-l would not provide any risk reduction since
contaminants would continue to migrate from the fill material to groundwater.
Alternative GW-3 would provide the highest degree of long-term effectiveness and protection.
Alternative GW-2 would rely more heavily on institutional controls and therefore is less effective
than GW-3. Alternative GW-I is not protective of human health because groundwater cleanup
levels would not be attained.
4. Reduction of Toxicity, Mobility, or Volume Through Treatment
Reduction of toxicity, mobililty, or volume through treatment refers to the anticipated
performance of the treatment technologies a remedy may employ.
Alternatives SC-3 and SC-4 would decrease the toxicity, mobility, and volume of the
contaminants because of the physical removal of the contaminants through hot spot removal and
vapor extraction, with ultimate destruction provided at a RCRA Subtitle C disposal facility. The
.active vapor extraction in Alternative SC-4 would require a longer timefrarne to achieve the
same results as the hot spot removal in Alternative SC-3. Alternatives SC-l and SC-2 would
not decrease the toxicity, mobility, or volume of the contaminants through treatment.
Groundwater " extraction and treatment in alternatives GW-2 and GW-3 would provide equally
effective reduction of toxicity, mobility, and volume of the contaminants. Alternative GW-l
would not provide treatment, and so cannot provide reduction of toxicity, mobility, or volume.
s. Short-term Effectiveness
Short-term effectiveness refers to the period of time needed to complete the remedy and any
adverse impacts on human health and the environment that may be posed during the construction
and implementation of the rem~y until cleanup levels are achieved.
FAFBICRUROD . 02101/93
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Alternatives SC-2 and SC-4 would provide protection within the shortest period of time.
Alternative SC-3 would provide a lower level of protection in the shon term because of
contaminant volatilization during the excavation process. Alternatives SC-2, SC-3, and SC-4
would rely heavily on restricted access to the CRL and strict site health and safety plans to
protect workers during the construction period. Alternative SC-I would be ineffective in the
shon term since contaminants would continue to migrate to the groundwater.
Alternative GW - 3 would provide the greatest protection in the shortest timeframe because of the
point-of-use treatment and alternative water supply elements. Alternative GW-2 would provide
a high level of protection in the shon term, but relies more heavily on institutional controls to
attain this protection. Alternative GW-I would not provide protection in the shon term.
6. Implementability
Implementability is the technical and administrative feasibility of the alternative. All source
control and groundwater alternatives can be implemented using existing technologies.
Alternatives SC-2, SC-3, and SC-4 would require that the cap be installed by experienced
installers, but both the materials and required personnel are available from a variety of vendors.
The active vapor extraction system would require more extensive construction, operation, and
maintenance than the passive system in the other two alternatives.
No unusual obstacles are expected in the installation of extraction wells required for the
implementation of Alternatives GW-2 and GW-3. Numerous wells have been installed to the
base of the upper aquifer without difficulty. Basalt outcrops near the east end of the southwest
landfill area that could limit the eastern extent on the vapor extraction system in that area.
Access/easements would be required for monitoring wells installed on adjacent lands, and
groundwater containment wells would be installed on the CRL property. Waste manifesting
would be needed to transpon waste (GAC filters) for off-site treatment.
7. Cost
Costs include estimated capital, operation, and maintenance costs, and net present worth costs.
Table II shows a comparison of total estimated costs for each of the alternative. .
For source controls Alternative SC-4 would be the most expensive source control, followed by
Alternatives SC-3 and SC-2. Alternative SC-l would have no initial costs.
Alternative GW-3 costs are slightly more expensive than Alternative GW-2. Alternative GW-l
would have minimal costs.
C. Modifying Criteria
Modifying criteria are used in the final evaluation of the remedial alternatives.
FAfBlCRlJROD - 02101/93
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8. State Acceptance
This criterion refers to the whether the state accepts the preferred remedial alternative.
"
v
The Washington Department of Ecology concurs with the selection of the preferred remedial
alternative. Ecology has been involved with the development and review of the Remedial
Investigation, Feasibility Study, Proposed Plan, and Record of Decision. Ecology comments
have resulted in substantive changes to these documents and has been integrally involved in
detennining which cleanup standards apply to contaminated groundwater under MTCA.
9. Community Acceptance
This criterion refers to the public's support for the preferred remedial alternative.
On August 25, 1992, Fairchild AFB held a public meeting to discuss the Proposed Plan for the
CRL. Prior to this meeting copies of the Proposed Plan were sent to over 200 local residents
and other interested parties. The results of the public meeting indicate that the residents of the
surrounding communities accept the preferred remedial alternative. Community response to the
remedial alternative is presented in the responsiveness summary, which addresses questions and
comments received during the public comment period.
x. mE SELECTED REMEDY
A combination of both source control and groundwater control actions is necessary to achieve
the broader objective of restoring contaminated groundwater in the upper aquifer to levels that
are protective of human health and the environment. The Air Force's selected remedy to meet
this objective at the CRL includes Containment with Active Vapor Extraction (Alternative SC-4)
and On-site Groundwater Extractionl Treatment with Off-site Point--of-Use Treatment and/or
Alternative Water Supply (Alternative GW-3). The m~jor components include:
.
Capping the northeast and southwest disposal areas at the landfill
.
Installing an active soil vapor extraction/treatment system in both capped
areas
.
Extracting contaminated groundwater from the upper aquifer at the landfill
boundary and treating by air stripping and granular activated carbon;
treated groundwater will be disposed of at an off-site location
downgradient of the CRL property
.
Monitoring off-site water supply wells within the off-site portion of the
plume and providing point--of-use treatment and/or alternative water supply
if needed in the future
.
Monitoring groundwater in upper and lower aquifers
FAFBICRUROD.02IOI/93
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.
Implementing institutional controls.
These components will restore groundwater to the groundwater cleanup level of 5 ug/L for TCE.
-
The active groundwater extraction/treatment system is intended to contain the contaminant plume
at the CRL property boundary. That portion of the plume beyond the property boundary will
be allowed to reach cleanup levels through natural dilution, degradation, and dispersion. The
groundwater cleanup levels will be attained throughout the contaminated plume at and beyond
the edge of the waste management unit, which is defined as the CRL property boundary. The
remedy can be implemented within I to 3 years and, when complete, would reduce the estimated
carcinogenic risk from the site to less than 1 in 100,000.
-------
C. Extracting Groundwater at the Landf"dl Boundary and Treating by Air Stripping and
Granular Activated Carbon
"
v
The objective of the groundwater extraction system is to prevent further migration of
contaminated groundwater from the source areas. To accomplish this, approximately 15
extraction wells 150 feet deep will be installed in the upper aquifer along the north and east
boundaries of the northeast fill area and the east boundary of the southwest fill area. The radial
capture zone for each extraction well is projected to be 40 feet. Preliminary calculations indicate
that an extraction rate of 200 gpm will be necessary to fully contain that portion of the plume
within the CRL property boundaries. .
~ .
Extracted groundwater will be treated using an air stripping unit. Air emissions from the air
stripper will be treated using granular activated carbon. The Spokane County Air Pollution
Control Authority has approved activated carbon as best available control technology for taxics
(T-BACT) for this site under Chapter 173-460 WAC. The design specifications for the air
stripping unit will be reviewed !by the Spokane County Air Pollution Control Authority to assure
that the emissions will comply with the substantive requirements of the regulations. Washington
State air quality regulations (Chapter 173-460 WAC) state that the ambient source impact level
(ASIL) of TCE cannot exceed 0.8 uglm3.
An estimated 0.13 pounds of GAC will be needed per 1,000 gallons of water. Spent carbon will
be managed in accordance with the EP A OSWER Directive 9834.11 which establishes policies
for off-site disposal of CERCLA wastes.
Extracted groundwater will be treated to meet the groundwater cleanup levels since the treated
effluent will be reintroduced into the upper aquifer. This will be accomplished using infiltration
trenches or reinjection wells at an off-site location downgradient of the CRL property. The
specific location and type of reintroduction will be chosen during the remedial design. The
estimated volume of groundwater requiring treatment is 1.6 billion gallons. The off-site
discharge will require a State Waste Discharge Permit (Chapter 173-216 WAC).
D. Monitoring Off-site Water Supply Wells and Providing Point-of-Use Treatment and/or
Alternative Water Supply if Needed in the Future
In the portion of the plume beyond the capture zone of the groundwater extraction system, point-
of-use treatment and/or alternative water supply will be provided to users of wells which are
constructed in compliance with state and local regulations as necessary to prevent consumption
by area residents of groundwater exceeding MCLs. Point-of-use treatment systems typically
consist of a f1ltration system installed at the well head for wells serving multiple users, or near
the point where piping from an individual user's well enters the user's building. Routine
maintenance and periodic replacement of system components will be necessary. Provision of
an alternate water supply will be considered based on factors such as the distance to an existing
water system or the amount of water delivered.
FAFBICRlJROD - 02101193
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E. Monitoring Groundwater in Upper and Lower Aquifers
Continued groundwater monitoring is necessary to evaluate the effectiveness of the remedial
action, to verify modeled predictions of contaminant attenuation, and to evaluate the need for
remedial actions in the lower aquifer. Known and suspected conduits for cross contamination
between the upper and lower aquifer were identified during the Remedial Investigation.
Groundwater monitoring will be performed in the off-site portion of the plume to verify the
decrease of contaminant levels as estimated in the FS. If monitoring does not confirm the
predicted decrease of contaminant level, the Air Force will evaluate the need to perform
additional response actions in accordance with all ARARs.
Approximately ten groundwater monitoring wells will be used to assess the effectiveness of the
remedial actions, determine when the Remedial Action Objectives have been attained, and to
evaluate the need for remedial actions in the lower aquifer. The wells will be sampled
periodically. In addition to TCE, the monitoring program will at a minimum analyze for vinyl
chloride and 1, l-DCE, since these analytes are breakdown products of TCE. Specific criteria
for compliance monitoring and decision-making will be developed in the Remedial Action
Management Plan, or art equivalent document.
F. Implementing Institutional Controls
Institutional controls will also be included as part of the selected remedy. These would include
controls on access and use of the site for the life of the cleanup, and a restriction attached to the
property deed. These controls will minimize human exposure to the contaminants that will
remain beneath the cap. The CRL will be fenced with warnings posted around the perimeter
to decrease contact with the contaminated soil and debris by the uninformed public.
Contaminated water supply wells within the contaminant plume will be inspected and
reconstructed or abandoned in accordance with Washington State regulation (173-160 WAC) if
necessary. Periodic meetings and media releases will be prepared to inform the public about any
issues or concerns regarding the CRL.
XI. STATUTORY DETERMINATIONS
Under CERCLA section 121, selected remedies must be protective of human . health and the
environment, comply with ARARs, be cost effective, and utilize permanent solutions and
alternative treatment technologies or resource recovery technologies to the maximum extent
practical. In addition, CERCLA includes a preference for remedies that employ treatment that
significantly and permanently reduces the volume, toxicity or mobility of hazardous wastes as
their principal element. The following sections discuss how the selected remedy meets these
statutory requirements.
. FAFBICRlJROD - 02101/93
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A. Protection of Human Health and the Environment
.
The selected remedy protects human health and the environment through source and groundwater
controls. Implementation of this remedial action will not pose unacceptable short-tenn risks
toward site workers or nearby residents. Installation of the landfill caps will prevent direct
exposure to contaminants within the landfill and will minimize the migration of contaminants to
the groundwater. Soil vapor extraction will pennanently remove contaminants from the fill
material, thereby providing long-term effectiveness of the containment system.
The groundwater extraction and treatment system will prevent migration of the contaminant
plume and pennanently remove contaminants from the groundwater. Contaminants will be
transferred from groundwater to the GAC and will ultimately be destroyed. The baseline risk
for a residential scenario associated with the groundwater exposure pathway is estimated at 7 x
10-3. The residual risks for this scenario at the end of the remedial action is estimated to be 6
x 1O~. .
Point-of-use treatment and/or provision of alternative water supply will provide protection to
users of groundwater in the off-site portion of the contaminant plume if it becomes necessary
during the remedial action.
Residual risks associated with the various vapor emission systems are estimated at 1 x 10-5. The
total residual excess cancer risk for the selected remedy is estimated at 2 x 10-5, which is
considered to be protective of human health and the environment.
B. Compliance with ARARs
The selected remedy will comply with the following federal and state ARARs that have been
identified. No waiver of any ARAR is being sought or invoked for any component of the
selected remedy. The ARARs identified for the CRL site include, but are not limi~ to, the
following:
Chemical-Specific ARARs
* Safe Drinking Water Act (SDW A), 40 USC Section 300, Maximum contaminant levels
(MCLs) for public drinking water supplies established for the SDW A are relevant and
appropriate for setting groundwater cleanup levels.
* Title V of Clean Air Act, Amendment of 1990, Section 112(b) of the Act lists sources
covered by the New Source Performance Standards and requires major emission sources
to obtain permits from federally approved state permitting agencies. This section defines
major sources as those with the potential to emit 10 tons per year of a hazardous air
pollutant. This Act would be applicable in detennining if Fairchild AFB could qualify
for exemption for emissions from the air stripper and active soil vapor system as non
major sources under section 502(a) of the Act.
FAfBlCRlJROD.02IOI/93
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* Resource Conservation and Recovery Act (RCRA), Subtitle C (40 CFR 261), Applicable
in identifying if the spent GAC filters from the air stripping system at the CRL are
considered a hazardous waste for purposes of transporting them off site for treatment.
* Emission Standards and Controls for Emitting Volatile Organic Compounds (VOCs) ,
(Chapter 173-400 WAC), Establishes standards in the state of Washington for specific
VOC source emissions; applicable in establishing emission standards for the active soil
vapor treatment/extraction system and from the GAC unit.
* Controls for New Sources of Toxic Air Pollutants (Chapter 173-460 WAC), WAC 173-
460-150 list TCE as a Class A toxic air pollutant with an acceptable source impact level
of 0.8 ug/m3. Section 030(c) states that contaminants with ASn.s between 0.1 to 0.99
ug/m3 would require a maximum emission rate of 50 pounds per year to qualify for a
small quantity exemption. Sections 040 and 050 provide procedures that must be
followed to satisfy permitting authorities that the emissions would meet small quantity
exemption status. This regulation would be applicable in determining if the emissions
from the active soil vapor extraction system or the treated emissions from the GAC unit
would qualify for small quantity exemption.
* Model Toxics Control Act Cleanup Regulations (MTCA), (Chapter 173-340 WAC),
Method B risk-based cleanup levels are applicable for establishing groundwater cleanup
levels.
Action-Specific ARARs
* RCRA Subtitle C (40 CFR 262)
Establishes standards for. generators of hazardous wastes for the treating, storage and
shipping of wastes. Applicable to the storage, packaging, labeling, and manifesting of
the spent GAC filters off site for treatment.
* RCRA, Subtitle D (40 CFR 258 Subpart F)
Establishes federal standards for the management of nonhazardous solid waste; relevant
and appropriate for the design, construction and maintenance of landfill containment
system. .
* Hazardous Materials Transportation Act (49 USC 1801-1813)
Applicable for transportation of potentially hazardous materials, including samples and
wastes.
* Noise Control Act (42 USC 4910)
Applicable for the design of air stripper system.
FAFBICRUROD - 02101/93
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. Dangerous Waste Regulations (Chapter 173-303 WAC)
Applicable for on-site treatment, storage, or disposal of dangerous waste of hazardous
wastes generated during the remedial action.
"'.
. Minimum Standards for Construction and Maintenance of Wells (Chapter 173-160 WAC)
Applicable regulations for the location, design, construction and abandonment of water
supply and resource protection wells.
. State Waste Discharge Pennit Program (Chapter 173-216 WAC)
Applicable regulations governing off-site discharges to groundwater. Applicable to the
extent that there is an on-site discharge to groundwater.
~ Minimum Functional Standards for Solid Waste Handling (Chapter 173-304-407 WAC)
Relevant and appropriate regulation for closure and post-c10sure care standards for
municipal solid waste landfills; specifies the design, construction and maintenance of
landfill containment system.
Location Specific ARARs
* No location-specific ARARs
Other Criteria, Advisories, or Guidance to be Considered for this Remedial Action
(TBCs)
* EP A OSWER 9834.11, Revised Procedures for P1annine and Implementine Off-site
ReS1JQnse Actions, November 13, 1987. This directive provides procedures for off-site
disposal of CERCLA wastes.
* EPA/540-SW-89-Q47, Technical Guidance Document: Final Covers on H:l7~rdous Waste
Landfills and Surface Impoundments, July 1989. Provides general guidance for landfill
cover design.
C. Cost Effectiveness
The selected remedy provides overall effectiveness proportionate to its cost. The capital and
O&M costs for Containment with Active Vapor Extraction are slightly higher than for the other
source control alternatives. However, this alternative will provide the highest degree of long-
term effectiveness because contaminants which would otherwise remain contained in the fill
material would be removed and treated. This will reduce the potential for continued
groundwater contamination.
FAFBICRUROD.02IOI/93
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D. Utilization of Permanent Solutions and Alternative Treatment Technologies to the
Maximum Extent Possible
The selected remedy -utilizes permanent solutions and alternative treatment technologies
practicable for this site. The remedy utilizes treatment of the contaminant source and of affected
groundwater within the CRL property boundaries. Soil vapor extraction provides a permanent
solution by removing contaminants which would otherwise remain contained within the landfill
material. Soil vapor extraction is considered an alternative treatment technology.
~
...
v
b
The risk from the groundwater contamination is permanently reduced through treatment without
transferring the risk to other media. The selected remedy provides the best balance of long-term
effectiveness and permanence; reduction in toxicity, mobility, and volume achieved through
treatment; short-term effectiveness; implementability; and cost.
E. Preference for Treatment as a Principal Element
The selected remedy satisfies the statutory preference for treatment by utilizing treatment as a
primary method to permanently reduce the toxicity, mobility, and volume of groundwater
contaminants and of volatile cOntaminants contained within the landfill. Treatment may also be
used at individual user well locations in the. event of off-site contamination of drinking wa~r
above MCLs.
xu. DOCUMENTATION OF SIGNIFICANT CHANGES
The Proposed Plan for the CRL was released for public comment in August 1992. The
Proposed Plan identified Containment with Active Vapor Extraction and On-site Groundwater
ExtractionlTreatment with Off-site Point-of-Use Treatment and/or Alternative Water Supply as
the preferred alternatives for source control and groundwater treatment, respectively. The Air
Force reviewed all written and verbal comments submitted during the public comment period.
Upon review of 'these comments, it was determined that no significant changes to the selected
remedy, as originally identified in the Proposed Plan, were necessary.
FAfBlCRUROD . 02101/93
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