EPA/ESD/R10-95/115
August 1995
EPA Superfund
Explanation of Significant
Differences for the
Record of Decision:
Fairchild Air Force Base
Craig Road Landfill, WA
12/5/94
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DEPARTMENT OF THE AIR FORCE
HEADQUARTERS 92D AIR REFUELING WING (AMC)
FAIRCHILD AIR FORCE BASE WASHINGTON
10 February 1995
92 CES/CEVR
100 W. Ent St, Suite 155
Fairchild AFB WA 99011 -9404
Environmental Protection Agency
Ms. Cami Grandinetti
Region 10 EPA
1200 Sixth Ave, HW-124
Seattle WA 98101
Dear Ms. Grandinetti
Attached is an Explanation of Significant Differences (ESD) for the Record of Decision for the
Craig Road Landfill at Fairchild Air Force Base. This document summarizes the decision to
remove the active soil vapor extraction system from the selected cleanup remedy. Also attached
is a technical analysis that was used in support of the ESD and its preparation.
Fairchild, the Environmental Protection Agency, and Washington Department of Ecology
participated jointly in the preparation of this document. Once we receive your formal acceptance
of this document we will provide public notice in a major local newspaper as required by section
300.435 (c) (2) (I) (A) and (B) of the National Oil and Hazardous Substances Pollution
Contingency Plan (NCP).
We appreciate your cooperation and assistance in both making the decision and preparing the
ESD. We believe this effort demonstrates the tri-party team spirit that has
allowed Fairchild to move expeditibusly forward in the cleanup program while demonstrating
good stewardship of available resources. If you have any questions regarding the ESD contact
Ms. Diane Wulf at (509) 247-5170.
Sincerely
/^
FREDERICK L/^lTTERK<
Assistant Civil'Engineer
Attachments
ESD & Tech Analysis
cc:
HQ AMC/CEVR (Mr. Daniel Murphy)
HQ AFCEE/ERD (Mr. Jonathan Haliscak)
AMC-Global Reach far America
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EXPLANATION OF SIGNIFICANT DIFFERENCES
FOR THE
RECORD OF DECISION
FOR THE
UNITED STATES DEPARTMENT OF THE ADR FORCE
CRAIG ROAD LANDFILL
FAIRCHILD ABR FORCE BASE, WASHINGTON
I. Introduction
This document presents an Explanation of Significant Differences (ESD) for the Record of
Decision (ROD) for the Craig Road Landfill (CRL) operable unit at the Fairchild Air Force Base
(FAFB), Spokane, Washington, which was signed by the United States Department of the Air
Force, The United States Environmental Protection Agency (EPA), and the state of Washington
Department of Ecology (Ecology) .on February 13, 1993. The CRL ROD was signed pursuant to
the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), as
amended by the Superfund Amendments and Reauthorization Act (SARA) of 1986. The site
name and location are as follows:
Craig Road Landfill Operable Unit
Fairchild Air Force Base, Washington
The lead agency for this action is the U.S! Air Force. EPA and Ecology concur with, and approve
the need for, this significant change to the selected remedy. The three agencies participated
jointly in the preparation of this document.
This ESD, prepared in accordance with section 117(c) of CERCLA and section 300.435(c)(2)(i)
of the National Oil and Hazardous Substances Pollution Contingency Plan (NCP), is necessary to
address needed modifications to the selected remedy identified in the CRL ROD. The significant
difference from the ROD consists of the elimination of the active soil vapor extraction (SVE)
system from the final remedy. The following reasons form the basis for this decision:
• Since the ROD was signed, field investigations and treatability studies have shown that
subsurface landfill conditions preclude effective and efficient utilization of SVE technology.
• In addition to the trichloroethene (TCE) source that was identified in the fill material during
the RI, there is subsequent monitoring well data which suggests that TCE may be present as a
dense nonaqueous phase liquid (DNAPL), possibly acting as a predominant source of
groundwater contamination.
• The remedy will still be protective of human health and the environment, and will still attain
applicable or relevant and appropriate requirements (ARARs).
. - 1 -
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• The additional cost of implementing the SVE system will not provide a significant decrease in
overall risk from contaminants at the site.
This and other relevant documents will become part of the AR file pursuant to Section
300.825(a)(2) of the NCP. Public notice of the ESD will be published in a major newspaper.
This ESD will be made available to the public for review at the following locations:
ADMINISTRATIVE RECORD
Spokane Falls Community College Library
W. 3410 Fort George Wright Drive
Spokane, WA 99204
INFORMATION REPOSITORY
Airway Heights City Hall
S. 1208 Lundstrom
Airway Heights, WA 99101 -
n. Site History, Contamination Problems, and Selected Remedy
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 a noncontiguous part of the
FAFB installation. This property is approximately 100 acres in area and is located on the west
side of Craig Road approximately 0.7 miles south of U.S. Route 2 and 0.6 miles east of FAFB
proper. (Figure 1).
The CRL was a former disposal location for FAFB. and was used for general purpose landfilling.
The site is composed of three inactive waste disposal areas. Municipal and industrial wastes were
buried in trenches on about 6 acres in the northeast disposal area (NDA), and in a low-lying area
of about 13 acres in the southwest disposal area (SDA). In addition, demolition debris form
runway reconstruction and other construction was deposited on the ground surface in the
southeast disposal area, covering about 20 acres (Figure 2).
The NDA was active from the late 1950s into the early 1960s. Landfilling in this area proceeded
by trench-and-fill, soil cover, and grading. The SDA was active from the late 1960s into the late
1970s. The method of disposal consisted of fill and-cover in a topographical low area, possibly
with some excavation. The soil cover was graded and then overlain with concrete blocks and
asphalt from the runway reconstruction. Based on investigation borings, the depth of the fill
materials below the existing ground surfaces exceeds 30 feet in the NDA and 25 feet in the SDA.
Environmental problems associated with the CRL were discovered under the U.S. Air Force's
Installation Restoration Program (IRP). The RI indicated the following problems at the site:
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UNITED STATES AIR FORCE
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FIGURE 1
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SCALE IN FEET
. UNITED STATES AIR FORCE
FAIRCHILD AIR FORCE BASE. WASHINGTON
CRAIG ROAD LANDFILL SITE
FIGURE 2
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.
.
TCE, 1, I-dichloroethene (DCE), and vinyl chloride have been detected in groundwater
samples trom on-site and/or off-site monitoring wells at concentrations exceeding federal
maximum contaminant levels (MCLs) established underthe Safe Drinking Water Act. TCE
was also detected in nearby residential and municipal water supply wells. In a 1989 removal
. action by the Air Force, users of those wells with concentrations exceeding federal MCLs
were provided with an alternate water supply. .
.
-
Two landfilled .areas (the NDA and SDA) within the CRL are identified as the apparent
sources of groundwater contamination.
.
Soil-gas measurements indicate that volatile 'contaminants are present within the fill material.
A ROD for this site was signed in February 1993. The ROD outlines the remedy that has been
selected to address the contamination described in the RI. The selected remedy for restoring
contaminated groundwater consists of both source' control and groundwater control actions. The
source control actions are intended to minimize migration of contaminants trom the fill material to .
the groundwater and to prevent direct exposures to contaminated subsurface soils and debris.
The groundwater control actions are intended to prevent further migration of contaminated
groundwater across the site boundary and to prevent the consumption by area residents of
groundwater which exceeds MCLs. The major elements of the selected remedy include:
.
Capping the NDA and SDA.
.
Installing an active soil vapor extraction and treatment system in each capped area.
.
Extracting contaminated groundwater trom the upper aquifer at the landfill, and treating by air
stripping and granular activated carbon; treated groundwater Will be reintroduced to the
aquifer at a location downgradient of the CRL'site.
.
Monitoring off-site water supply wells within the off site portion of the plume and providing
point-of-use treatment and/or alternate water supply ifneeded in the future.
.
Monitoring groundwater in the upper and lower aquifers.
.
Implementing institutional controls.
The remedial design (RD) for implementing the selected remedy began in February 1993. As part
of the RD, a treatability study to establish the design parameters of the SVE system was
performed. In addition, groundwater pumping tests were conducted to determine design flow
rates for the extraction wells, and groundwater samples were collected ITom extraction and
monitoring wells.
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.
, m. Description of and, Rationale (0, Significant Differences
The active SVE system wilt be deleted from the selected remedy described in the ROD. the
other elements of the selected remedy will be implemented. Some additional components may
need to be incorporated into the passive gas management system of the landfill cap to provide for
treatment of the volatile organic compounds (VOCs) which were to be removed by the SVE
system, and which now may be intermixed with the gases generated by the landfill. Thes~
determinations will be made through coordination with the Spokane County Air Pollution Control
Authority. .
EP A and Ecology have concurred with the Air Force's decision to delete the SVE system from
the selected remedy. The rationale for deleting the active SVE system are described below. A
detailed technical analysis supporting this decision is provided in the AR for F AFB Attachment 1.
.
Subsurface landfill conditions preclude effective and efficient utilization of SVE technology.
During the Rl, soil-gas surveys indicated high concentrations ofvarious.VOCs. The selected
remedy included.the SVE system as an element to address these contaminants. A post-ROD
treatability study was conducted to provide engineering infonnation needed to design the SVE
system. The treatability study indicated that the fill material displays considerable spatial
variations in air permeability and in contaminant concentrations. Because of the variations in air
permeability, it is likely t~at preferential pathways for vapor flow would develop in the fill material
during the vacuum extraction process. Such pathways would intersect the zones of higher .
contaminant concentrations only by coincidence. Consequently, only a limited portion of the fill
material and of the cont'aminants contained in it could be expected to be remediated by the SVE
system. ' .
.
In addition to the, tricWoroetherie (TCE) source identified in the fill material, there is evidence
that TCE maybe present as a dense nonaqueous phase liquid (DNAPL), possibly acting as the
predominant source of groundwater contamination.
The screening of remedial alternatives and remedy selection in the Feasibility Study (FS) and th~
ROD were based on the Rl's conclusion that the fill material was the primary source of ,
contaminants, which leach from the fill to the groundwater. To address this migration pathway,
the selected remedy included the capping of the fill materials to minimize theieaching, and the
SVE system to reduce the volume of contaminants available to be leached.
However, post-ROD groundwater samples have indicated VOCs in the aquifer below the SDA at
concentrations that suggest that TCE may be present as a DNAPL. Thus there may be two
primary sources of groundwater contamination ,
associated with the CRL, and particularly with the SDA: the fill material and a
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DNAPL. Of the two, a DNAPL could be expected to be the predominant source for ongoing'
contamination, particularly with the leaching of contaminants from the fill material minimized by
capping the disposal areas. With a DNAPL source, the emphasis of remedial action would shift to
the controls on contaminant migration provided by the groundwater extraction and treatment
system. Active remediation of the contaminant vapors in the fill material would not provide a
significant enhancement of the groundwater restoration in this situation.
.
The remedy will still be protective of human health and the environment, and will stili attain
ARARs.
The baseline risk assessment found that approximately 83 percent of the carcinogenic risk
associated with the site arose from exposures to contaminants in groundwater. The selected
remedy will accomplish reduction of these risks through groundwater migration controls and.
through the provision of point- of-use' treatment and/or alternate water supplies as needed. The
SVE system would not directly address exposures to contaminated groundwater. While the
remaining 17 percent of the site's overall carcinogenic risk is associated with exposure to vapors
escaping from the landfill, that risk will still be adequately reduced by. the capping element of the
selected remedy. Noncarcinogenic health effects were not a factor in developing the selected
remedy.
The ROD identifies state and federal ARARs to be used as cleanup standards for the
groundwater, but does not identify any cleanup standards for the fill material. This is appropriate
since the fill material will be contained with a landfill cap. The deletion of the SVE system by
itself from the selected remedy will not affect the remedy's attainment of ARARs.
.
The additional cost of implementing the SVE system would not provide a significant decrease
in overall risk from contaminants at the site.
The total present worth cost of the selected remedy as described in the ROD is estimated to be
$8,722,073 over thirty years. The FS, in which cost estimates for each element of the selected
remedy were developed, indicates that the present worth cost-of the SVI;: system is $1,612,523
over thirty years. As explained above, the SVE system would provide no signifiGant decrease in
overall risk from contaminants at the site, but woul.d represent about 18.5 percent of the total
project cost.
IV. Affirmation of Statutory Determinations
The modifications to the proposed remedial actions will continue to utilize permanent solutions
and treatment to the maximum extent practiCable for the site. Based on the information gained
during RD from the treatability study and groundwater monitoring, it has been determined by the
Air Force, EP A, and Ecology that the elimination of the SVE system will not affect the ability of
the remedy to achieve cleanup levels. Additionally, the remedy will remain protective of a human
health and the environment, comply with federal and state ARARs, and is cost-effective.
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. . . .
,
V. Public Participation Activities
This ESD and the contents of the AR are available for public review. In addition to the AR on file
for the ROD, the AR for this action includes a copy of this ESD, the RD workplai1, the RD,
treatability study reports for the SVE system and groundwater pump test, the RA workp~an, and
other supporting information. This action will be implemented with the construction of the final
landfill cap layers, which is expected to begin with the next construction field season in the spring
of 1995. Although modified from the original ROD, the remedy doesn't present a fundamental
change in scope or purpose of this action. Thus a formal comment period will not be conducted..
Consistent with Section 300.435(c)(2)(i) of the NCP, this ESD has been placed in the previously
listed F AFB Information Repositories, after the publication of a notice in the following
newspaper:
Spokesman-Review (Spokane)
The public is encouraged to revie~ this ESD and other relevant documents in the AR and to
provide comments to any of the agencies involved. Additional information may be requested
within 14 days of the notice of issuance of this ESD by contacting:
92 ARW/PA
Major Candyce Ballmer
1 E. Bong Street
FAIRCHILD AFB W A 99011-8517
(509) 247-5170
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TECHNICAL ANALYSIS
IN SUPPORT OF THE
EXPLANATION OF SIGNIFICANT DIFFERENCES
FOR THE
RECORD OF DECISION
FOR THE
UNITED STATES DEPARTMENT OF THE AIR FORCE
CRAIG ROAD LANDFILL
FAIRCHILD AIR FORCE BASE, WASHINGTON
I. Introduction
This document provides the technical analysis used in determining the need for
a modification to the selected remedy identified in the Record of Decision
(ROD) for the Craig Road Landfill (CRL) operable unit at the Fairchild Air
Force Base (AFB), Spokane, Washington. This analysis will serve as a
supplement to an Explanation of Significant Differences (ESD) that was
prepared to document the rationale for the modifiation. The significant
difference from the ROD consists of the elimination of the active soil vapor
extraction (SVE) system from the final remedy.
II. Site History, Contamination Problems, and Selected Remedy
Fairchild AFB is located approximately 12 miles west of Spokane, Washington.
The CRL is located on property owned and operated by U.S. Air Force as a
noncontiguous part of the Fairchild AFB installation. This property is .
approximately 100 acres in total area and is located on the west side of Craig
Road approximately 0.7 miles south of U.S. Route 2. The CRL was a former
disposal location for Fairchild AFB and was used for general purpose
landfilling and is now comprised of three inactive waste disposal areas.
Municipal and industrial wastes were buried in two of the areas (Northeast
Disposal Area (NDA) and the Southwest Disposal Area (SDA)) and demolition
debris from runway reconstruction was deposited on the ground surface in the
third disposal area.
Environmental problems associated with the CRL were discovered under the U.S.
Air Force Installation Restoration Program (IRP). The remedial investigation
indicated the following problems at the site.
TCE, 1,1-DCE, and vinyl chloride have been detected in groundwater
samples from on-site and/or off-site monitoring wells at
concentrations exceeding federal maximum contaminant levels (MCLs)
established under the Safe Drinking Water Act. TCE was also detected
in nearby residential and municipal water supply wells. In a 9189
removal action by the Air Force, users of those wells with
concentrations exceeding federal MCLs were provided an alternate
water supply.
- Two landfilled areas (NDA and SDA), within the CRL were identified as
the apparent sources of contamination.
— Soil-gas measurements indicate that volatile contaminants are present
within the fill material.
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~
,
The selected remedy for restoring contaminated groundwater consists of both
source control and groundwater contr~l actions. The source control was
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 groundwater control actions are intended to prevent further
migration of contaminated groundwater across the site boundary and to prevent
consumption by area residents of groundwater which exceeds MCLs. The major
components of the selected remedy include:.
Capping the northeast and southwest.disposal areas at the landfill.
Installing an active soil vapor" extraction and treatment system in
each capped area.
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 a
location downgradient of the CRL"site.
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
Implementing institutional controls
III.
Technical Analysis
The selected remedy identified in the ROD will be modified by deletion of the
specified active SVEsystem for the CRL. The Air Force's proposal to delete
this system has been agreed to by EPA and Ecology. The reasons for this
modification are described in the ESD. The following provides a more detailed
technical analysis supporting this decision.
The ROD stated that SVE is necessary ftto actively remove volatile contaminants
contained within the landfill...and satisfy the statutory preference for
treatmentft. The basis for this determination was, in large measure,
predicated on data discussed in the feasibility study (FS) prepared by SAlC
(August 1992). The FS indicated that active vapor extraction, a proven long
term solution, would remove contaminant sources throughout the life of th~
cap. Sourc~ estimates determined during the Remedial Investigation (RI)
conducted by SAIC (April 1992), based on the results of soil gas surveys of
t~e NDA and SDA landfill sites, indicated high concentrations of various
volatile organic compounds (VOC). These soil gas measurements, however, were
taken at a depth of three feet below the ground surface, which was generally
located within the cap rather than the landfill. The soil cap had a mean
depth of approximately 5.1 feet (standard deviation = 3.6 ft). Soil. cap
character ranged from silt/sand to silt and clays (RI,SAIC, April 1992).
These findings, regarding cap construction, were partially confirmed during
the soil vapor extraction treatability study (Engineering Science, November
1993). Engineering Science, however, measured gas phase concentrations at two
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.
.
vapor extraction wells, which were screened well within the two landfill
domains, and observed considerably lower soil gas values than reported by
SAlC. Corrected average landfill air permeabilities, for the NDA and SDA
sites, were calculated to be 52 and 67 darcys, respectively (Hoag & Grasso,
1994). The air permeability of the existing confining cap.is expected to be
much lower (0.1 to 1 darcys, Grasso, 1993) for the soil types described
above. Based on the physics of gas phase VOC transport, lower concentrations
are expected in t~e cap as compared to the landfill. However, the
juxtaposition of the limited data reported by SAIC (1992) and Engineering.
Science (1993) indicates the reverse, i.e. higher cap concentrations as
compared to the landfill gas. The lower landfill gas concentrations may be
attributable to spatial (lateral and vertical) averaging and perhaps diffusion
limitations within various strata in the landfill. This data indicates
concentration heterogeneities within the landfills which would, most likely,
compromise the efficacy of SVE system operation.
Landfills are generally quite heterogeneous and anisotropic, with. varying
moisture contents and perched water tables. SVE treatability study results
indicate a significant depth related variation in subsurface vacuum .
measurements in a given borehole. For example, at steady state operation,
(time = 1980 minutes) at vacuum monitoring point A (VMPA) at the NDA site (see
Engineering Science, November 1993), the 15' and 27' depths had soil vacuum
levels of 0.048" H20 and 0.37" H20, respectively (i.e~, nearly an order of
magnitude difference). At VMPB borehole, the 5' 15' and 19.5' depths
exhibited vacuum levels of 0.015" H20, 0.026" H20' and 0.2" H20,
respectively. This clearly indicates that a layered physical heterogeneity
exists. Similar data is reported for the SDA area. Implementation of an SVE
system in these landfills would result in an advective air flow through the
most pervious strata in the subsurface, remediating only a portion of the.
landfill. The remaining lower permeability strata would be diffusion limited
and require significantly longer clean-up times, which would increase
remediation costs.
Finally, although the ROD and theRI/FS consider remediation of the landfill
sites as a source control approach, there is evidence that the. major active
source of groundwater contamination may not be the landfills. SVE
treatability results identified the presence of approximately 30 different
VOCs in the landfills (Engineering Science, November 1993). Of these
compounds, approximately 21 were observed at significant concentrations (less
than 100 ppbv). However, although TCE was observed at concentrations
comparable to other contaminants in the landfill gas, only TCE was detected in
groundwater samples in significant concentrations (ROD 1993). When comparing
frequency of detection of contaminants in groundwater, TCE was observed in 48%
of samples from all wells and 92% of samples from boundary wells (ROD, 1993).
Other VOCs were detected at frequencies that ranged from 0.8 to 5.5% and ° to
14% for.all wells and boundary wells, respectively. Furthermore, although
bis(2-ethylhexyl)phthalate was observed twice as. frequently (14%) as the next
closest compound in boundary wells, its occurrence may have been a result of
laboratory or field contamination (ROD, 1993). Using a risk based criteria as
determined by the State of Washington's Model Toxics Control Act, only the
following groundwater compounds were identified in the remedial action
objectives (RAO) for clean-up (ROD, 1993):. TCE, 1,1-DCE, and vinyl chloride.
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;
. . .".
,
The frequency of observation of 1,1-DCE and vinyl chloride were 0.8% and 0 and
0.8% and 2.6% for all wells and boundary wells, respectively. Maximum
observed concentrations for TCE, 1,1-DCE, and vinyl chloride were 2800, 2.0
and 0.8 ug/L, respectively. The detection limit range for these compounds
were 0.12-2 ug/L (TCE), 0.13-2 ug/L (l,l-DCE), and 0.18-5 ug/L (vinyl
chlo~ide). The ROD states that "cleanup levels will be considered to be
attained if these ~ompounds are not detected above practical quantitation
limits". consequently, for two of the three compounds identified in the ROD,
maximum. observed concentrations were within the detection limit range.
Moreover, 1,1-DCE and vinyl chloride are common degradation products of TCE,
suggesting that these progeny species may have derived from subsurface
transformations rather than migration from the landfill. TCE appears to exist
in the landfill gas at concentrations comparable to other RAO VOCs (TCE = 3400
- 4900 ppbv; 1,1-DCE = 340-3300 ppbv; vinyl chloride = 1400 - 13000 ppbv,.
Engineering Science, 1993). Furthermore, air/water partitioning constants
(log KH (atm * L): .
mole
TCE = 1.03; 1,1-DCE = 1.32 (calc.); vinyl chloride = 1.35, Schwarzenbach, et
al., 1993, Verschueren, 1977) indicate that TCE, 1,1-DCE, .and vinyl chloride
should have similar aqueous .concentrations in the. landfill.. However, since
TCE should be less mobile t~an the other compounds (log Kow: TCE.= 2.24;
1,1-DCE = 1.70 (est); vinyl chloride = 0.60, Schwarzenbach, et al., 1993), the
lack of significant presence of other RAO compounds in groundwater implies the
existence of. a TCE source other than the landfill, such as a dense non-aqueous
liquid (DNAPL) pool(s). Removal of VOCs from the landfill would therefore be
unlikely to significantly impact the. source of groundwater contamination.
Moreover, the proposed landfill cap and associated passive vapor recovery
system to be installed at both the NDA and SDA sites will further minimize the
potential migration of VOCs into the groundwater.
The heterogeneous nature of VOC distribution and landfill stratigraphy,
coupled with evidence that the landfill may not .be the direct active source of
groundwater contamination indicates that elimination of active vapor
extraction from the ROD is warranted.
IV.
References
1.
Engineering Science, Vapor Extraction System Letter Report-Final;
November, 1993.
Grasso, D., Hazardous Waste Site Remediation: Source Control, Lewis
Publishers, 1993.
Hoag & Grasso, Groundwater Extraction, Treatment, Infiltration, Cap and
Vapor Extraction System - Craig Road Landfill (CRL) Fairchild Air Force
Base - Sixty (60) .percent Design Review Comments - Letter Report, 1994.
Record of Decision, Craig Road Landfill.
. SAIC, Remedial Investigation Report, Craig Road Landfill, April 1992.
SAIC, Feasibility Study Report, Craig Road Landfill, August 1992.
Schwarzenbach, R., Gschwend, P.;Imboden, D., Environmental organic
Chemistry, Wiley-Inter Science, 1993.
Verschueren. K., Handbook of Environmental Data on Organic Chemicals,
Van Nostrand Reinhold, 1977.
2.
3.
4.
5.
6.
7.
8.
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,
site Name:
INITIAL
NAME
DATE
EXPLANATION OF SIGNJ:FICANT DIFFERENCES
Concurrence
Fairchild AFB - Craig Road Landfill
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