FIVE YEAR REVIEW REPORT
FOR THE
AREA D/AMERICAN LAKE GARDEN TRACT
NATIONAL PRIORITIES LIST SITE
McCHORD AIR FORCE BASE, WASHINGTON
February 2000
PREPARED BY:
UNITED STATES AIR FORCE
INSTALLATION RESTORATION PROGRAM
ENVIRONMENTAL MANAGEMENT FLIGHT
62 CES/CEVR
McCHORD AIR FORCE BASE, WA 98438-1325
REVIEWED AND APPROVED BY:
WASHINGTON DEPARTMENT OF ECOLOGY
TOXICS CLEANUP PROGRAM
OLYMPIA, WASHINGTON 98503
AND
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION X, FEDERAL FACILITIES SECTION
SEATTLE, WA 98101
-------
I. INTRODUCTION
A. PURPOSE
McChord Air Force Base (AFB) conducted a Five-Year Review and prepared this
report consistent with the requirements of Section 121 (c) of the Comprehensive
Environmental Response, Compensation and Liability Act (CERCLA) as amended and
Section 300.430 (f) (4) (ii) of the National Oil and Hazardous Substances Contingency
Plan (NCP) and the Washington State Model Toxics Control Act (MTCA). The review is
also consistent with the State of Washington Administrative Code (WAC) 173-340-420.
The Area D/American Lake Garden Tract (Area D/ALGT) National Priorities List
(NPL) Site is required to have a Five-Year Review to.ensure that the remedial action
remains protective of human health and the environment and is functioning as designed.
This review is a type la review that is applicable to a site at which the response is
ongoing.
B. SITE CHARACTERISTICS AND HISTORY
The Area D/ALGT NPL Site is located approximately 7 miles south of downtown
Tacomain central Pierce County, Washington. The site is roughly bounded by Interstate
5 and Porter Hills to the west; McChord AFB ammunition storage area to the north.
Burlington Northern Railroad to the east, and Fort Lewis Logistics Center to the south as
shown on Figure 1. Area D, located in the southwest portion of McChord AFB, had
several areas of disposal in various stages of operation from the mid-1940s to the early
1970s. The ALGT is an off-base residential tract abutting the southwest boundary of
Area D, between McChord AFB and Ft. Lewis Army Installation.
A contaminant plume, consisting of trichloroethylene (TCE), resides in the
shallow aquifer beneath Area D and extends approximately 3,500 feet downgradient of an
old landfill (Landfill 5) into the northeast corner of the off-base ALGT. The plume is
believed to originate from secondary sources beneath the former landfill. The plume also
contains cis-1,2- dichloroethylene (cis-l,2-DCE). Vinyl chloride and
1,1-dichloroethylene (1,1-DCE) have also been detected in the plume.
Seven sites in Area D were originally identified during the 1982 Phase I Record
Search (CH2M Hill. 1982). The Phase I record search investigation identified past and
current potential waste disposal sites at McChord AFB. The follow-up Phase II
investigation measured low level organic contamination at Area D. The investigation
discovered TCE in ground water monitoring wells installed in the residential American
Lake Garden Tract (ALGT). Ground water contamination in the ALGT was believed to
have originated in Area D of McChord AFB, in the vicinity of a former landfill ( Landfill
5). The seven sites found in Area D were subsequently listed on the NPL on September
21, 1984, as the Area D/American Lake Garden Tract Site. The seven sites were Landfill
4, Landfill 5, Landfill 6, Landfill 7, Ordnance Disposal Area 26, Radioactive Disposal
Well 35, and Old Burn Trench 39. Upon listing, the investigation phased into the
2
-------
PROJECT
American Lake
Garden Tract
Figure 1: Vicinity Map - Site Boundary Map
3
-------
Comprehensive Environmental Response, Compensation and Liability Act (CERCLA)
Remedial Investigation - Feasibility Study (RI/FS) process.
In September 1985, a Memorandum of Agreement was signed by the U. S. Air
Force (USAF), U.S. Environmental Protection Agency (EPA), Washington Department of
Ecology (WDOE), Washington Department of Social and Health Service, and the Tacoma
Pierce County Health Department that required the installation of a permanent alternative
water supply for the ALGT. McChord AFB tasked the Army Corps of Engineers to study,
design, and oversee the installation of a water line connecting the ALGT to a local water
utility, the Lakewood Water District. By mid-1986 the residents within the 5 micrograms
per liter (ug/1) portions of the TCE contaminant plume had been connected to the public
water system. As a follow-up action, the Air Force offered free hookups to all property
owners in the ALGT in 1992. All property owners in the ALGT who accepted the offer,
were connected to Lakewood Water District's water supply system by June 1993.
The RI, which began in 1988 (Ebasco, 1991) characterized the nature and extent of
contamination in the ground water, soil, surface water and sediments. The Human Health
Risk Assessment (Ebasco, 1990) and the Ecological Risk Assessment (Ebasco, 1991)
evaluated potential effects of the contamination on human health and the environment.
The FS (Ebasco, 1991) evaluated alternatives for remediation of the contamination. The
chosen remedial action alternative stated in the Record of Decision (ROD) (Ebasco, 1991)
included the connection of all ALGT residents to a public water system and the extraction
and treatment of ground water in a long-term effort (possibly 30 years) to remediate the
drinking water aquifer. It was determined in the ROD that only the contaminant plume
associated with Landfill 5 required remedial action. The other six sites that comprise the
Area D/ALGT NPL Site were determined to not pose an unacceptable risk to human
health or the environment as defined by the NCP.
The remedial action selected in the ROD was restoration of ground water to its
beneficial use, a drinking water source, which is a Long-Term Response Action. The
engineered remedial action consists of three extraction wells that remove contaminated
ground water that is emanating from Landfill 5, and one treatment plant that treats the
contaminated water. Volatile organic contaminants (VOCs) are removed from the water
using an activated carbon adsorption treatment system. The treated water is analyzed to
insure that it meets the cleanup goals and then discharged into an infiltration trench. The
system started operating on February 15, 1994 and has been operating as designed.
II. REMEDIAL ACTION OBJECTIVES
On September 19, 1991, the ROD was signed by the U. S. EPA Regional
Administrator, the WDOE Program Manager for the Toxics Clean-up Program, and the
Wing Commander of McChord AFB. The ROD addressed the selected remedy for the
ground water plume. The parties decided that remedial action was not necessary for source
control to protect human health or groundwater. The major components of the chosen
Remedial Action were to install three groundwater extraction wells capable of
4
-------
capturing the groundwater contaminant plume in the unconfined aquifer. One of the
extraction wells was installed near the area of highest concentration of contaminants. This
action creates a hydraulic barrier to prevent further off-base migration of contaminants at
concentrations above the Maximum Contaminant Level (MCL) and treats the most
contaminated ground water.
The treatment plant consists to two tanks, each containing 20,000 pounds of
granulated activated carbon (GAC). The tanks are set in series, so that the contaminated
water flows through both tanks before being discharged into one of the infiltration
trenches. The contaminants are filtered out of the water by the GAC. The GAC in the first
tank is replaced with virgin carbon when the 1,2 cis-DCE concentration in the water
leaving the second tank reaches 15 ug/1. The tank with the virgin carbon becomes the
second tank in the series after the spent carbon is removed. The spent carbon is shipped off
site, to an EPA approved regeneration facility.
The water is periodically sampled at the extraction well heads, at various
monitoring wells across and around the plume, and at the discharge point of the treatment
facility. The sampling frequency for the first two years of operation of the system can be
found in the Remedial Action Work Plan (RAWP) written by the Corps of Engineers
(COE, 1994). The RAWP was designed to insure that contaminated water was not
discharged into the infiltration trench and thus released into the environment. The RAWP
also was designed to monitor the levels of contaminants within and around the plume, to
ensure that unexpected changes were not occurring. The actual sampling and monitoring
requirements found in the RAWP, are carried out by an environmental consulting firm
under contract to McChord AFB. This contractor also performs routine operation and
maintenance of the system.
The sampling requirements in the RAWP are modified every year, as more
information is gained from the operation of the system. The current sampling requirements
can be found in the Addendum to the Management Plan for Ground Water Treatment
Plant Operations at Area D/American Lake Garden Tract (URS Greiner Woodward Clyde
and Foster Wheeler Environmental Corporation, April 1999). Sampling and maintenance
have been performed according to the schedules in the RAWP and the Addendum to the
Management Plans, since the system began operating in February 1994.
Administrative and institutional controls have been implemented at the site. These
controls include the permanent alternate water supply for the ALGT, long term
monitoring, access restrictions, notification to appropriate agencies and public awareness.
The long term monitoring of the contaminant plume includes using both on and off site
wells to detect any changes in the plume. Access restrictions were put in place when the
former landfills and the contaminant plume were placed on McChord's Base
Comprehensive Map. The Base Comprehensive Map is used for planning all future
developments. The maps used to screen all proposed projects on base, to ensure that the
projects won't impact an environmental site. Although the baseline risk assessment
determined no unacceptable risk exists in the soil for future residential use. McChord AFB
directives also prohibit future development above former landfills. McChord directives
also restrict the use of the shallow ground water within Area D and any
5
-------
AppimimBte
Location of
Groundwater
Treatment Plsnt
nj. n.
¦AY
Ul'Kr
LEGEND
TOE Concentration - 4 pflJl-
<9KM«nMf199t(
— — 6rtmctwr< ViMl Plptlln* lecaacn
(T) Bnnetion W»«ta
KW
Figure 2: Site and Ground Water Extraction Well Map
6
-------
activities that may cause contact with the contaminated portion of the shallow ground
water. In 1997, McChord purchased approximately 20 acres of private land in the ALGT
for additional base housing. Those 20 acres included the area of the ALGT that was above
the contaminated portion of the plume that extended off-base. The additional 20 acres are
now controlled by McChord AFB and under the strict institutional controls enforced by
McChord AFB.
The treatment system has removed 13 kilograms of TCE and 33 kilograms of cis-
1,2 DCE from the ground water between February 15, 1994 to December 31, 1999. The
size of the plume, as defined by the 5 ug/1 TCE contour has greatly decreased during the
first five years of operation. Figure 3 is the TCE Ground Water Evolution Map, which
shows the size of plume at the end of the 1991 RI and the size of the plume in September
1998. The areal size of the 5 ug/1 plume in 1998 is about a third of the size of the 5 ug/1
plume in 1991. The size of the .5 ug/1 and 50 ug/1 plumes have also decreased.
The three extraction wells are capturing and containing the contaminant plume,
based on the quarterly water level monitoring and mapping that has been performed since
the system started in 1994. The wells pump most of their water from the less
contaminated layer that underlies the most contaminated layer of the plume. Thus,
contaminants in the ground water samples are subject to dilution leading to sample
concentrations lower than the concentrations in the most contaminated layer of the plume.
Samples collected in downgradient containment wells DX-1 and DX-2 since spring
of 1995 have been below the RAOs. Similarly, samples collected in downgradient
confirmation wells DA-28 and EPA W-5 have been below RAOs since the system started.
Samples have also been collected from DO-1, DO-la, DZ-13, DT-1, DA-30a, and
DA-30b, which are downgradient monitoring wells associated with DX-1. Since the spring
of 1995, samples collected from these wells have also been below the RAOs.
Similarly, samples have been collected from DA-1 la, DA-1 lb, DO-2, DR-05, and
DT-2, which are downgradient monitoring wells associated with DX-2. Since the spring of
1995, all but two samples collected from these wells have been below the RAOs. The two
exceptions were collected from DO-2 in December 1997 and September 1999.
Extraction well DX-3 is located in the area of highest contaminant concentration.
Samples collected from DX-3 are still above the RAO for TCE. The average level of TCE
in DX-3 was 26.5 ug/1 for the first two quarterly sample rounds in 1994. The average level
of TCE in DX-3 has decreased to 13.5 ug/1 for the last two quarterly rounds of 1998. The
levels of TCE in DX-3 have fluctuated from a high of 39 ug/1 before the system began
operation (March 1992) to a low of 10 ug/1 (June 1997). Figures 4 and 5 show the TCE
and cis-DCE concentrations respectively, in the extraction wells from February 1994
through December 1998.
7
-------
y \\
\ '""I //;! i
N^*""T^~ij' ~g--~T\---v—t1 J //yii .
j> Wj !' /5
A C< "'r
[\P
9e*«ii£Mi
LiatiiD
ICf Cmmniiian «r CUH jugA-
rll«
¥C£ 5 «^V
l>Iii'ii^>1ipium.JhuRMi * OkApoA.
¦i>1avit «H tflnvM <%iiMi * I pgii.
Figure 3: Ground Water TCE Plume Evolution Map
8
-------
TCE Concentration in Extraction Wells Over
Time
McChord AFB Area D
Figure 4: TCE Concentrations in Extraction Wells Over Time
9
-------
cis-l,2-DCE Concentrations in Extraction
Wells Over Time
McChord AFB Area D/ALGT
Site
80
6*
A
C
iL>
V
E
V
CxQ
U
i
in
cis*1,2-DCE fcmcdiaiion goal Far groundwater (70
'
IQ
M
s»
o
c
i
e
¦*
(S
9
(ft
SO
ir.
&
>c
5C
<¦
9
*e
•*
r*i
DX-1
D X -'2
DX-3
Figure 5: Cis 1,2-DCE Concentrations in Extraction Wells Over Time
10
-------
III. RECOMMENDATIONS
McChord AFB recommends making some modifications to the chosen RA. As
stated in the ROD for the American Lake Garden Tract Site, "the system's performance
will be monitored and adjusted as warranted by the performance data collected during
operation."
The performance data collected during the first five years of operation warrant
evaluating the first modification listed on Page 84 in the ROD, which is "Discontinuing
pumping at the individual wells where cleanup goals have been attained." McChord
recommends placing Extraction wells DX-1 and DX-2 on standby and monitoring the
levels of TCE near the two wells.
Ground water samples collected from extraction wells DX-1 and DX-2 have had
concentrations of TCE and cis-DCE below the RAOs for the past four years. This
indicates that contamination has been reduced in the area around and upgradient from
DX-1 and DX-2, as shown in the contaminant evolution map (Figure 3). DX-3 is the only
extraction well with influent concentrations still above the RAOs. Therefore, it is
recommended that DX-1 and DX-2 be turned to standby.
Concentrations of contaminants in the vicinity of these two extraction wells would
be monitored using nearby wells to observe whether the concentrations increase. The
adjacent observation wells (DO-1 and DO-2) could be monitored quarterly at appropriate
depths and/or the recently installed upgradient monitoring wells (DT-1 and DT-2) could be
monitored quarterly.
The frequency of sampling and location of sampling wells for this compliance
monitoring would be negotiated by McChord and Ecology personnel. The sampling
schedule would be put in the Addendum to the Management Plan. If concentrations above
the ROAs were to show up in any of the selected monitoring wells, then the extraction
well(s) would be turned on, to capture any contamination that may have passed the well
location.
Figure 6 is a quarterly ground water elevation contour map with the estimated
capture zones for the three extraction wells. This figure is from December 1998. It is
similar to other quarterly ground water contour maps that have been made since the system
started. The size of the capture zones increase as the water levels drop during the dry
season (May through October) and decrease as the water levels rise during the rainy season
(November through April).
IV. STATEMENT ON PROTECTIVENESS (supplied by WDOE)
The WOE certifies that the remedy selected for this site remains protective of
human health and the environment.
11
-------
®as*w* Pwa » a&mtm
» tomarnmrtimmiiamtmrm
— — Eonnrfiimjr Sw&miim
stmAiw ftnUHmcttiir
mmcfMi
mmi
taMipf
—*— ft«*
timmsm
CwatffMJ^pnpfcsff
toi^wdnr
Figure 6: Ground Water Elevation Contour Map with Extraction Well Capture
Zones for December 1998
12
-------
V. STATEMENT ON PROTECTIVENESS (supplied by EPA)
The EPA certifies that the remedy selected for this site remains protective of
human health and the environment.
VI. NEXT FIVE-YEAR REVIEW
The nest five-year review will be conducted by September 2004.
Signed by EPA Date
Date
Date
(Reports/AMLK3 01. doc)
13
-------
USB/
# jSL l
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION 10
1200 Sixth Avenue
Seattle, WA 98101
EPA had reviewed the February 2 000 Five Year Review
Report for the American Lake Garden Tract NPL site. Based
on our review of this document, EPA concurs that the remedy
is currently
protective of human health and the environment.
However, the institutional controls established in the
September 1991 ROD for this site do not contain all the
requirements for institutional controls for operating
federal facilities established in EPA's "Region 10 Final
Policy on the Use of Institutional Controls at Federal
Facilities", May 3, 1999. Therefore, as required by the EPA
Region 10 policy, and to ensure that this remedy is
protective in the long-term, an Explanation of Significant
Differences adding these requirements to the selected remedy
needs to be prepared by the Air Force and Ecology. This ESD
should be completed no later than September 30, 2000.
Mike Gearheard, Director
Environmental Cleanup Office
cimage F00-10001-m>
Date
-------
CONCURRENCE
Five-Year Review Tot American Lake Gardens
Name
Dale
Signature
Bev Gaines
3/2-' i c G
r_-C- %{ r- : *./*
| Seth Leap trot
J/2V/CO
Uudi Scfctwar2
"b/7 >h>
Ik^l-
I Amber Wong
I a>
u
3
r. ' ,'4
-h 4-*U0J&te-^£r^<:U t
r<-
------- |