United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
EPA/ROD/R10-91/032
September 1991
&EPA
Superfund
Record of Decision
American Lake Gardens
-------
.
REPORT DOCUMENT A T10N 1" REPORT NO. I ~ 3. Aec:ipl8nl'8 Acc.8Ion No.
PAGE EPA/ROD/R10-91/032
4. TItle 8nd Subtitle 5. Report D8te
SUPERFUND RECORD OF DECISION 09/19/91
American Lake Gardens (McChord AFB-Area D), WA &.
First Remedial Action - Final
7. Aulhor(8) 8. PItrfomIIng Org8nlDtlon R8pt. No'
8. PiIrfonnIng 0ra8lnlz8llon II8me 8nd ~ 10. Projlc:tlTaklWork UnIt No.
11. ConIract(C) cw Gr8nt(G) No.
(C)
(G)
1 ~ Spon8orIng OrganIzatIon II8me 8nd Adch88 13. Type of Repor1& P8t1ocI Cowred
U.S. Environmental Protection Agency 800/000
401 M Street, S.W.
Washington, D.C. 20460 14.
15. Supplemen18Jy No-
16. Ab81ract (UmI1: 2110 _nI8)
The American Lake Gardens (McChord AFB-Area D) site is an active U.s. Air Force base
located at McChord Air Force Base, Pierce County, Washington. The site consists of
two areas, Area D and American Lake Garden Tract (ALGT). Area D is located entirely
on-base. Area D activities include Air Force Base administration, flight operations
support functions, and housing and recreation facilities. Approximately 2,384
people reside in the Area D housing facilities. ALGT is an off-base commercial and
residential area with approximately 3,431 residents and various businesses.
Hydrogeologic units exist on site including a series of confined and unconfined
aquifers that appear to be hydraulically connected. Vario~s-surface water bodies
exist near the site and are principally ground water-fed. From the mid-1940's to
the present, no known industrial activities have occurred in the ALGT area; however,
seven waste disposal sites have operated within the Area D portion of the site. In
1981, the Air Force initiated a multi-phase program to identify past disposal sites
and contaminants and to eliminate public health risks. Concurrent with DOD
investigations, EPA discovered TCE in ground water monitoring wells installed at the
ALGT, and in 1984, concluded that waste disposal sites in Area D were the likely
(See Attached Page)
1.7. Doc:ut.-I AnaIy8I8 L DeecripIof8
Record of Decision - American Lake Gardens (McChord AFB-Area D), WA
First Remedial Action - Final
Contaminated Medium: gw
Key Contaminants: VOCs (benzene, PCE, TCE, toluene, xylenes), other organics,
metals (arsenic, chromium, lead)
b. 1den1ifier8lOpen-En T-
c. COSA 11 ReIcIIGroup
18. AV8i18b111y St8Iement 18. Seariy CI... (Thi8 Report) 21. No. of PaIl88
None 102
20. Securi1y CI... (This Page) n Price
NrmA
ANSl-m.18
50272 101
-
..
\
'"
(See
SMIn8ttucIi- on~-
(F0I'm8Ity NTJS.35)
-------
EPA/ROD/R10-91/032
American Lake Gardens (McChord AFB-Area D), WA
First Remedial Action - Final
Abstract (Continued)
.
source of ground water contamination. Modeling studies indicate that most of the soil
contamination by VOCs has moved into the ground water, and that DNAPLs may continue to
act as a secondary source of ground water contamination. In 1986, the Air Force provided
an alternate water source to residents of ALGT, and subsequently connected 80% of the
residences to a public water supply. This ROD addresses remediation of the contaminated
onsite and offsite ground water plume, as a final remedy. The primary contaminants of
concern affecting the ground water are VOCs including benzene, PCE, TCE, toluene, and
xylenes; other organics; and metals including arsenic, chromium, and lead.
The selected remedial action for this site includes pumping and treating both the onsite
and offsite ground water contaminant plumes in the confined aquifer using an onsite
multi-bed carbon adsorption treatment facility, followed by recharging or irrigating the
treated ground water onsite; regenerating the spent carbon offsite; monitoring the ground
water contaminant plume; and implementing institutional controls such as deed, ground
water, and land. use restrictions. The estimated present worth cost for this remedial
action ranges from $4,445,000 to $6,949,000, for interest rates of 10% and 4%
respectively, which includes an annual O&M cost of $341,000 for years 0-2 and $318,000
for years 3-30.
PERFORMANCE STANDARDS OR GOALS: Ground water will be restored to levels consistent with
State and Federal MCLs. Chemical-specific goals for ground water include cis-1,2-DCE 70
ug/l (MCL), 1,1-DCE 0.7 ug/l (Model Toxic Control Act), TCE 5 mg/l (MCL), and vinyl
chloride 0.04 ug/l (Model Toxic Control Act) .
~
-------
. . .
... ...... .. RECORD OF DECISION .. .
McCHORD AIR FORCE BASE, WASHINGTON
American Lake Garden Tract .
..
u.s. E.P.A. Region 10
McChord Air Force Base
Washington State Department of Ecology
September 19, 1991
-------
RECORD OF DECISION
Cor the
UNITED STATES AIR FORCE
AREA D/AMERICAN LAKE GARDEN TRACT
McCHORD AIR FORCE BASE, WASHINGTON
TABLE OF CONTENTS
Declaration of the Record of Decision
Decision Summary
Introduction
I. Site Name, Location, and Description
TI. Site History and Enforcement. Activities
. nI. . Community Relations
IV. Scope and Role of Response Action Within Site Strategy
V. Summary of Site Characteristics
VI. Summary of Site Risks
VTI. Description of Alternatives
VITI. Summary of Comparative Analysis of Alternatives
.' IX.' The selected Remedy .
X. The Statutory Determinations
XI. Documentation of Significant Changes
. .
. Responsiveness Summary .
..
Page
1
5
7
8
9
42
72
78
.. .82.
87
90
-------
.
DECLARATION OF THE RECORD OF DECISION
SITE NAME AND LOCATION
Area DI American Lake Garden Tract
McChord Air Force Base, Pierce County, Washington
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected final remedial action for Area DI American
Lake Garden Tract (Area DI ALGI) at McChord Air Force Base, Washington, which was
chosen in accordance with the Comprehensive Environmental Response, Compensation,
and Liabi~ty Act of 1980, as amended by the Superfund Amendments and
Reauthorization Act of 1986, and to the extent practicable, the National Oil and
Hazardous Substances Pollution Contingency Plan (NCP). This decision is based on the
administrative record for Area D/ALGT.
The State of Washington concurs with the selected remedy~
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from this site to the groundwater, if
not addressed by implementing the response action selected in this Record of Decision,
may present an imminent and substantial endangerment to public health, welfare, or the
environment.
, DESCRIPTION OF THE SELECTED REMEDY
Remedial action is not necessary for source cOntrol to protect human, health or
groundwater, surface water, or sediments. It has been determined that contaminant
, ~ncentrations found in the soil do ~ot pose an unaccep~ble risk to hum,an, h,ealth. or the
environment, as defined by..the NCP; , , '
...
The seJected remedy (Alternative 3) for Area DI ALGT addresses remediation of
groundwater contami~ation by eJiminating or reducing the risks posed by the site to levels
-------
The major components of the selected remedy include:
.
Install groundwater extraction wells capable of capturing the groundwater
contaminant plume in the unconfined aquifer. An estimated three extraction
systems will be necessary to achieve this goal.
.
Install one of the three groundwater extraction systems near areas of highest
concentration of contaminants within the contaminant plume.
.
Install on-site groundwater treatment facilities to remove contaminants from the
extracted groundwater. The preferred treatment is carbon adsorption, with an
estimated two treatment facilities necessary to achieve this goal.
.
Monitor the groundwater contaminant plume and the extraction/treatment system
during groundwater remediation activities to ensure that groundwater remediation
goals' are achieved and maintained throughout the contaminant plume.
, ,.
Implement administrative and institutional controls such as restrictive covenants and
McChord Air Force Base command directives, that supplement engineering
controls and minimize exposure to releases of hazardous substances during
remediation.
: STATUTORY DETERMINATIONS
, .
The selected remedy is protective of human health and the environment, complies with
Federal an" State requirements that are legally applicable. or relevant and appropriate to
the remedial action, and is cost effective. This remedy utilizes permanent solutions and
alternative or resource recfJvery treatment technologies, to the maximum extent
practicable, and satisfies the' statutory 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 in the
. gro~ndwaterabove hea1th:-?ased levels, a review will be conducted within five years after
cOmmencement of ,remedial action to ensure that" the remedy ',continues 'to prOvide' .
adequate protection of human health and the environment. '
.
-------
Signature sbeet for the foregoing McChord Air Force Base Record of Decision
between the United States Air Force and the U.S. Environmental Protection AgenCy,
witb concurrence by the Washington State Department of Ecology.
Jl~
DANA RASMUSSEN
Regional Administrator, Region 10
U.S. Environmental Protection Agency
~q( L0!lt
Da
.
,
--.. .~~':.
\
...
-------
.
Signature sheet for the foregoing McChord Air Force Base Record of Decision
between the United States Air Force and the U.S. Environmental Protection Agency,
with concurrence by the Washington State Department of Ecology.
~(
HOWARD J. I
Commander, 62
Iq~ql
Date
-------
Signature sheet for the foregoing McChord Air Force Base Record of Decision
between the United States Air Force and the U.S. Environmental Protection Agency,
with concurrence by the Washington State Department of Ecology.
..
( 1 .....:) -I.
~ -" A. ....::::r ~ 1/..0/
CAROL FLESKES, PROGRAM MANAGER
Toxics Clean-up Program .
Washington State Depanment of Ecology
.
_Blc; /q /
Date
'"
-------
McChord AFB Area DI ALGT ROD
Page
1
DECISION SUMMARY
INTRODUCTION
The McChord Air Force Base (AFB) Area DI American Lake Garden Tract (ALG1) was
listed on the National Priorities List (NPL) in October 1984, under the Comprehensive
Environmental Response, Compensation, and Liability Act of 1980 (CERCLA or
Superfund), as amended by the Superfund Amendments and Reauthorization Act of 1986
(SARA).
Pursuant to Executive Order 12580 (Superfund Implementation) and the National Oil and
Hazardous ~ubstances Pollution Contingency Plan (NCP), the Air Force performed a
.. Remedial InvestigationIFeasibility Study (RIfFS) for Area DI ALGT. The Remedial
Investigation (RI) (1991) characterized the )1ature and extent of contamination in the
groundwater, soil, surface water, and sediments. The Human Health Risk Assessment
(1990) and the Ecological Risk Assessment (1991) evaluated potential effects of the
contamination on human health and the environment. The Feasibility Study (FS) (1991)
evaluated alternatives for remediation of the contamination.
I.
SITE NAME, LOCATION AND DESCRIPTION
The Area DI ALGT site is located in Pierce County, Washington, approximately one mile
south of Tacoma (Figure 1). The site is bounded by: Interstate 5 and Porter Hills to the
north; McChord AFB ammunitio~ storage area, "A" Street, and Burlington NQrthern
Railroad (BNRR) to the east;.Fort Lewis Logistics Center boundary with.ALGT to the
south; and ALGT to the west.
A.
Area D
. .
Area D. is loeate(f entir~ly ~n-b~ in the ~uthwe~t portio~ ~f McCho~d .m.. Activitie~ .
within Area D include AFB administration, flight operations support functions,. and . ...
housing and recreation facilities. Area D has had several waste disposal sites in various
stages of operation from the mid-1940s to the present. These disposal sites were
-------
McChord AFB Area D/ALGT ROD
Page
Hartwood Housing Area, which is situated along the western bOundary of Area D,
consists of 860 housing units with a population of approximately 2,384. Families reside
in the housing area for an estimated 2.5 to 3 years, with some tenants remaining up to 11
years.
B.
ALGT
ALGT is an off-base residential tract abutting the southwest boundary of Area D be!Ween
McChord AFB and Fort Lewis Army Installation. This tract consists of approximately
1,183 housing units. Approximately 3,431 people reside in ALGT. Up to 80 percent of
the residents are renters, and over one-half of the residents move each year due to
frequent transfe~ of military personnel.
Commercial activities have been limited to barber shops, equestrian facilities, gasoline
service stations, grocery stores, laundromats, restaurants, and vehicle repair shops. No
known industrial activities occurred within the ALGT.
c.
Surface water and Groundwater Resources
..
Seven on-basewiiter supply wells are installed' in th~ vicinlty of.theAreaD." With the ,.
exception of one family housing ewell, which was disconnected . at the time of sampling,
all wells were sampled during the RI. One well, the Whispering Firs Golf Course
irrigation well, exhibited contamination that exceeded drinking water standards. This
well is used' exclusively for irrigation of the golf course during. the summer months. The
remaining wells are' located out of the path of the plume either horizontally' or are beneath
the contaminated shallow aquifer. .
. '. ..
.'
Approximately 86 percent of the drinking water for ALGT residents is: s~pplied by the' '.
Lakewood Water District. The remaining residents continue to use private wells that are
installed beyond the known contaminant plume boundary. Water supplied by the
Lakewood Water Distri,ct is dra~ .frpID three public watersup~ly well~, ~hic~ are..
. located more than'.one mile from the Area D/ALGT plume and are. screened in the.
uncontaminated lower aquifer. These wells are sampled on a quarterly basis by the.
jurisdictional health department, and are not known to be currently affected by the
contaminant plume.
. .
.
2
Ii
-------
CM'"
/ "
, /
t'
1;;-
>/'
~~.> ~}.'
WI' hiD 1'0.
"
" ~~' '~LV
" '.... '"" ",if' / '...l'.,'~tt>'t.""-"''J:.~...~.. , ,.:, ,,} , " J If /j
. ... :"J~~:~,;,::,,:~~~~;'~~~$~\j!~.u::t~1~2~~--'~~,~:'; ...:. ... s-
, ,,', '.l '1,~ '...,...~'...,'~ "-"~' ,-~' ,,~.~ . "C"\<";"':"'.'J I:' I ,'," I --, ,.1. I., r: ,! .' "~.I-' . '" J' '.. ,
-;~-,j.,:,.;}~,f'i,tI~j!ir....:n~~,J\ i~:' <__)T.:J ;<>t~j'~~~~.;)t,N
'... ">c~z..z~~t;<:I£~:'{I.~-,r'I;i',;Jif'IIj:'.:'!I.{," ./,'L""'" ";::;::;;.'-"" ",', '~.... '~~...., ',; ': "'~' .<. ',', ~..':<.-;: :'"
, . ," "'/.~,"i"~~ '4'~~.~....."".~...:.~,:-,.....~-;i~"~!I'~iJ.':,~~" ,-. ~...:' . ~:. .B.dtfl'!~ .:;...., r'..~, '. :f.". :'-"." '..' . \.';'
',' 'J."'s,\'.. ';";'~;'!>.L.;;7""-r"l'!J~'J-" .'i"'" 'I,' .'.. ", "{fr ..-,:, .. '.. \"""f".' " " '."
A>13f~~~1i~~7~~~~~~lr:-c".'_~~;;:6~;~~~:~' .... ~(:\.z ',:.\; .: t I'~i
'. ""- ~- ,,-"". '" r \,' , ." ~,/... J1! /'\' .t1,\" r;" '," I ' ~ ' ,,:#.
'-Lj~ '. .. '-"~7~:':-~~'C, ~ ~," ,...' :,:',. :,.-":r:;,;?;.:?:r~?1-~.~:,> rn}:! I LiO/ [!'~'\I.id}:(~4';~n 1.; ,s"£,[ :~: j
: :ct AmerIcan L.ke ".. "'.. o=~ "'''''....'ond.. ",...".,~ I : '\ .' .',:~. ' w..k......' I " >'/ " '--'~:'~" ..~ :
SI!ATItJ!
"
"
"
'<
..
-.
Ore. 0 III
';"::-:::::..
":-"
"-'.
"
Page
3
LEGEND
~ INSTALLATION RESTORATION
PROGRAM (IRP) SITES
~
SURFACE WATER BODIES
STUDY AREA BOUNDARY
..............
I
N
I
0 SOO 1000
Scale (f.et)
A
Gtnefalzed Subsutfac8
Pro.1e Loc:adon
A
'"
A'
McChord All Force Bas...",.. OIAlGT
Figure t
McCHORD AND ALGT STUDY AREA
-
-------
McChoi'd AFB Area Df ALGT ROD
Page
5
The nearest surface water bodies are Lamont Lake, the Duck Pond, Baxter Lake,
Whitman Lake, Carter Lake, an unnamed pond in ALGT, Emerson Lake, and Lake
Mondress (Figure 1). These surface water sites are principally groundwater-fed.
n.
SITE HISTORY. AND ENFORCEMENT ACTIVITIES
The Department of Defense (DOD) Installation Restoration Program (IRP) was initiated
at McChord AFB in March 1981. The purpose of the multi-phase program was to
identify the locations and contents of past disposal sites and to eliminate the hazards to
public health in an environmentally responsible manner. The Phase I record search
investigation identified past and current potential waste disposal sites. The Phase n
investigation measured low level organic contamination at several of these sites across.
McChord AFB and recommended further studies to confirm contaminant characteristics
and distribution.
Concurrent with the United States Air Force's (Air Force) Phase n IRP investigation, the
United States Environmental Protection Agency (EPA) discovered TCE in groundwater
monitoring wells installed at the ALGT, and in 1984, concluded that the groundwater
contamination in the ALGT most likely originated from Area D. The site was
subsequently listed on the NPL in October 1984. Upon listing, the IRPinvestigation was
phased into the CERCLA RIfFS process.
A.
Source Areas
Seven waste disposal sites within Area D were identified and investigated as potential
sources of contamination during the RI. .These sites are depicted in Figure 1 and ...
described in Table 1.
B.
Groundwater
.. ". .
. . '. . .
. Once it was determined that Area D was the likely source of groundwa~r contamination,.~
the Air Force provided an alternate water source to residents of ALGT. Beginning in the-
summer of 1986, the Air Force offered connection to the Lakewood Water District to
residents of ALGT.. Approximately 80 percent of the ALGT residents, incJuding all
residents directly affected by the contaminant plume, were permanently transferred to the
Lakewood Water District water supply. The private drinking water wells were generally
not abandoned.
-------
. .
-"---.......-
"
Table 1.:.. Area D Waste Site History - ~c~hord Air Force Base.
Waste Approximate
Disposal Time of General.Waste. Specific Waste Land Use Prior Current
Site Operation Type Received Type Received To Waste Disposal Land Use
'4.: 1941 - 1958 Unknown UnknoWn Gravel pit Soccer Field
(sporadic use)
1958 - 1978 Rubbish, garbage Unknown
Industrial
. 5 . 1951 - 1967(1) Industrial, domestic, Waste oil, fuel, Unknown Golf Course
construction solvents(1)
6' 1961 (1) - Present Industrial, domestic, Unknown Borrow pit Borrow pit, landfill
construction
7 1967 - 1972 Industrial, domestic, Unknown Pond Golf Course
construction
, :26. 1943 - 1956 Ordnance disposal Grenades, fragmentation Unknown Undeveloped
bombs, industrial
fuels(1), chemicals(1)
19601. 1979(1) Stumps, grass Stumps, grsss
35. 19501 -1959(1) Low-level radioactive waste Rinsate from Well of undetermined Golf Course
decontamination of radar depth
components, fluorescent
dials; possibly medical
waste liquids Z
Waste JP-4v solvents, Unknown Golf Course
(9
POL
39
1953 . 1960(1)
Waste POL~/, sofvents, fuel
1/ POL.. petroleum, oil, and lubricant
21 JP-4- jd fuel '
0\
, .
, .
.
-------
McChord AFB Area DI ALGT ROD
Page
7
C.
Enforcement
A Federal Facilities Agreement (Agreement), Administrative Docket Nos.
1088-06-17-120 and 1088-06-18-120, between the Air Force, the EPA, and the State of
. Washington Department of Ecology (Ecology) became effective October 23, 1989. The
Agreement establishes a procedural framework for agency coordination and a schedule
for all CERCLA activities conducted at McChord AFB.
Under the terms of the Agreement, EPA and Ecology provided oversight of the
remainder of the RIlFS activities for Area D/ALGT. In accordance with CERCLA
Section 120, the Air Force and the EPA, in collaboration with Ecology, selected the final
remedy in this Record of Decision (ROD).
m. COMMUNITY RELATIONS
A.
.Community Relations During the RIlFS
In accordance with 55 FR 8847, community interviews were conducted with interested
residents, local officials, and public interest groups to identify concerns an~ public.
information needs, and to solicit involvement in the Superfund process. The information
gathered during the interviews provided the basis for development of the site-specific
Community Relations .Plan (CRP). Under the CRP, the following activities were
undertaken to address community concerns and interests.
.
Information repositories containing site inf~rmation and documents on site activities
were established M' the'following four lOcations:
Pierce County Library - LakewOOd Branch
Pierce County Library - Tillicum Branch
McChord AFB - Library.. .
. McChord APB - Public Affairs Office
...
.
Three workshops to inform the public of the status and findings of the site
investigation were held:
-------
MeChord AFB Area DI ALGT ROD
Page
November 9, 1989 (summarized preliminary results of the environmental
samples)
March 20, 1990 (discussed the findings of the remedial investigation)
Three factsheets and three press releases were issued to correspond with the
workshops.
Also, in accordance with Section 113 (k)(I) of CERCLA, an administrative record was
established to provide the basis for selection of the remedial action. The administrative
record was available for public review at the McChord AFB Environmental Engineering
Office.
B.
Community Relations to Support Selection or a Remedy
In accordance with Sections 113 (k)(2)(B)(i-v) and 117 of CERCLA, the public was given
the opportunity to participate in the remedy selection process. The proposed plan, which
summarized the alternatives evaluated and presented the preferred alternative, was mailed
to approximately 850 interested parties in March 1991. The Air Force provided notice
through a display ad in.the Tacoma Morning News Tribune and the Lakewood JOU17UJl to
explain the proposed plan; list the. public comment period, and announce the public
meeting. A news release was provided to the local news media which resulted in news
coverage by the Tacoma Morning News Tribune on March 31, 1991. A meeting of the
Citizen Advisory Committee, comprised of local government officials, environmental
interest groups, and local residents, was also held to disseminate. information on the
proposed plan.
A 45-day comment period was held from March 25 to May 8, 1991. There were no
requests for extensions. Approximately 30 people attended a public meeting held on
. .
April 11, 1991 atWoodbrook Junior High School. The written comments, which were
received during the public comment period, are included in the Responsiveness Summary
attached to this.ROD.
IV. . SCOPE AND ROLE OF RESPONSE ACTION wITinN SITE STRATEGY
The R1 evaluated the nature and extent of contamination in all potentially affected media
including groundwater, soil, surface water, and sediment. However, with respect to the
soil, the objective of the RI was to investigate the soil as potential sources of volatile
.
8
.
-------
McChord AFB Area D/ALGT ROD
Page
9
organic compound (VOC) groundwater contamination. Thus, the RI is not a complete
characterization of the sources; nonetheless, based on available data, the soil does not
appear to be a source of continuing contamination for the groundwater.
Results from the RI and the Baseline Risk Assessment indicate that no remedial action is
necessary for soil, surface water, or sediments to ensure protection of human health or
the environment. Groundwater contamination does exceed health-based levels andlor
MCLs and will require remediation as outlined in this ROD. Therefore, the final
remedial action selected in this ROD addresses groundwater contamination at the
McChord Area DI ALGT site. Groundwater will continue to be monitored biannually for
VOCs, (semi-volatile organic compounds (SVOCs), inorganics, and pesticides. If
additional contamination is identified, additional investigation andlor remediation of the
groundwater- or source areas may be required.
. The final selected remedy includes: (1) no remedial action for soil, surface water, or
sediments; and (2) treatment of contaminated groundwater to permanently and
significantly reduce the volume and mobility of the hazardou~ substances found within th~
saturated zones. .
.
,
v.
SUMMARY OF SITE CHARACTERISTICS.
A.
Site Geology and Hydrogeology
Area DI ALGT is located on an extensive upland glacial drift plain which occupies much
of central Pierce County (Table 2, Figure 2). The site ~nsi~ts of highly permeable sand
and gravel glacial outwash materials separated by till layers and interspersed non-gla~al .
units.
,
The uppermost hydrogeologic unit generally found across the site is the Vashon
Drift/Post Kitsap Aquifer. which consists of the Steilacoom Gravel. and recessional
outwash, till, and advance outwash units as well as lacustrine silt and undifferentiated
outwash and till units. The Steilacoom Gravel and the outwash units contain the .~
unconfined aquifer unit that extends from the water table at about 20 feet below ground to
a depth of between 80 and 160 feet. The underlying Kitsap Formation is a non-glacial
unit that generally represents a regional aquitard, but ~oca1ly has been found to be
discontinuous and relatively permeable. The Salmon Springs Drift Aquifer underlies the
-------
___0..' ...
T bl 2
f G t
. U'
a e . escnDtton 0 eo 021C mts.
GEOLOGICI SITE SITE SITE
STRA TIGRAPlUC GEOLOGIC SYMBOL LITHOLOGIC DESCRlYfION TlUCKNESS HYDROGEOLOGIC
UNIT UNIT ,; Fr. DESIGNATION
Fill f Pred~minantly silty gravel with varying amounts of garbage. 0->25 Aquifer where
saturated
Recent Recent Deposits Qr Predominantly alluvipm and colluvium; silt, sand and gravel 0-10 Aquifer where
with lesser amounts of or~anic depression fillin~s. saturated
Vashon Stade-Fraser Steilacoom Gravel Qvs Open-work coarse gravel with abundant cobbles. 20-40 locally Vashon DriftlPost
Glaciation (Vashon absent Kitsap Aquifer
Drift) Vashon Qvr Interbedded gravelly sand and sandy gravel with variable
Recessional amounts of silt, typically medium dense to dense. 0-50
Outwash
Vashon Till I Qvt Very dense lodgement till: gravelly, clayey, sandy silt; and 0-20 locallYI (Qvt-aquitard)
loose ablation till: gravelly, clayey, sandy silt. up to 100
Vashon Advance :rl; Qva Interbedded uniformly graded sand and sandy gravel with silt
Outwash lenses, typically dense to very dense, local lenses of gravelly 5-90
sand.
Vashon Drift and Undifferentiated Qv Alluvium and outwash: interbedded gravelly sand, uniformly V arlable
Pre- V ashonl Outwash graded sand and sandy gravel, with silt lenses.
Post-Kitsap
Lacustrine Silt Qml Glacial and non-glacial lacustrine silt, locally with organic 0-30 (Qml-aquitard)
debris, locally interbedded with sand and silty sand.
Pre-Vashonl Undifferentiated Qtu Lodgement till, and lesser amounts of ablation till: 0-20 (Qtu-aquitard)
Post-Kitsap Till predominantlv verY dense to hard, sandy silt and cIavev silt.
Olympia Interglacial Kitsap Formation Qk Non-glacial deposits of silt, sand, gravel, and clay; with I~O Kitsap Aquitard
sCattered ash, wood, and peat. locally absent
Salmon Springs Salmon Springs Qss Interbedded sand and gravel with silt and clay lenses. 60-100 Salmon Sferings
Glaciation Outwash Aaui er
(Salmon Springs Salmon Springs Qsst Very dense, heterogeneous mixture of gravel, sand, clay, 2-55 Salmon Springs Till
Drift) Till and silt. Aauitard
Puyallup Interglacial Puyallup Qpy Alluvial deposits of interbedded silt and coarse-grained up to 135 Puyallup Aquitard
Formation ~i sediment with mud flow deposits and ash.
Stuck Glacial Stuck Drift Qst Till, lacustrine silt and fine sand, glaciofluvial sand and 50-100 Stuck Drift Aquifer
gravel.
D
'\ :
.
"'d
~
n
-
o
\
-------
J~"
A
w.,t
300
50
I.
[,;
...
I
,.
;
Tdlict.lm
1'51
Am8riun lak. Gvden T.ad
LCcChord ArB
Secllon 8-0'
I
SKllonC.C:-
I ..
.....
~i
i
OA.12. DA~12
~I
I
.....
'r
I
i
St:ctlon E.E'
I
,
SecllonD.D'
I
A'
e...
T.11
I
.....
So<-
I
i
i
12.& DA.20
--, r- Po."
McGuire
I
.....
-
I
i
i
TZ.(;1 OA.16
I I
T.12
I
r.o
I
lC.36
I
Ovs
<-""1-
~ ...7
.'---
-- --
.
.
-
~
q.
~ I Ov
..
--
-....
s,AlC)lIOGAA'OO.
.----
.....--
.,.:t@::fttt:..::.:J;GGf;
--...
......,
------
........
-
........'"
as.
NOTE: Loca/ion of cross-section can be found on Figure 1.
. 1000
I..HHHHI
Horizontal Sea" in Feel
V.rtical En~e'ation .20X
2000
!
)
)
)
Page
11
LEGEND
-=~=~OA"'_=':'
............
SttpIemb8ftse8-
WalefL~tlrom -w.."'-
rweYiOUl llU6n) --""
.,...--
COn~ Be-eft - "'*' G8do9c Units
Soil Trpes -
~Ur8I"""Aqullal'dPiopef'MS
[ill ~~~:~
~
t.~UNI~slfe,..~OftT.b18
Z. Contacll MIWNfISoIloWIiIs...,. ....,pte. "-
boring Ala 8tId well DO'" are appro""",
VM\Jfons be",,",," "'081 wwt.-c:onc:tI'ICn
mlye.isl
3. E1nIIioAAl.aebtailwdhntli'pOQf",*mlP
~bJEnvtoIpM,.~tndllram"""ton
'UIWJ' OCIfJIfIewd tit' Hcr\Oft 0enI'd & AI~"'1n:.
(HGVO It~).
McChord Air Force Base - Area DfALGT
Figure 2
SUBSURFACE PROFILE ALONG AN
EAST - WEST AXIS
-------
..
McChord AFB Area D/ ALGT ROD
Page
13
~
. The,deepest unit evaluated during the RI is the Puyallup Formation, which is generally an
aqui,tard.
Unconfined groundwater flow beneath the site is generally from the east or southeast to
the west or northwest, with some diversions caused by the drumlins of the Wescott and
Porter Hills. The gradient varies, across the site and by season, between 4 to 60 feet per
mile. Groundw~ter flow velocities similarly vary from 0.01 to 1 foot per day, with a
, median'velocity of approximately 0.5 foot per day.
In the underlying Salmon Springs confined aquifer, the flow is in a similar direction to
the west or northwest at a gradient of 20 to 60 fe
-------
McChord AFB Area DI ALGT ROD
Page
14
New and existing wells were sampled for VOCs, SVOCs, pesticides, polychlorinated
.~biphenyls (PCBs),. and inorganics. Table 3 summarizes the RI groundwater sampling
data. . . . ....
. ..
Pesticides and PCBs were not detected in the groundwater. Elevated levels of inorganic
compounds were detected in many of the wells without a discemable pattern or apparent
plume.. Samples were taken of both filtered and unfiltered metals, and exceedances of
MCLs were reported in the total metals samples of lead (one sample), chromium (one
sample), barium (one sample), and cadmium (four samples, plus five filtered samples).
Based on the upgradient groundwater analytical data, the presence of these inorganic
compounds was determined to be attributable to naturally occurring concentrations in the
glacial drift, which is generally present in the suspended sediment normally found in
monitoring wells screened in silty units.
"'
The primary contaminants found in the groundwater were trichloroethylene (TCE) and
cis-l,2-dichloroethylene (DCE). The contaminant plume, which is approximately 3500 .
feet in length, 500 feet in width, and 40 feet thick, extends from the vicinity of Site 5&39
and travels west in a curving path into the northeast comer ALGT. Figure 3 shows the
distribution of TCE across the site and indicates areas that are above and below the MCL
of 5 ugn (micrograms per liter). The maximum average concentration of TCE (76 ugn)
was found at well DA-Q7b.
Figure 4 shows the distribution of the DCE contaminant plume. The maximum average
concentration of DCE (222 ug/l) was similarly found at well DA-Q7b. The extent of the
plume exceeding the MCL is significantly greater for TCE than for DeE. The source of
the DCE is not known. . Its presence may be attributable to an impurity of TCE solvent
or may have been a degradation product of TCE within the aquifer.
The results of the RI investigation were incorporated into a groundwater model for
contaminant transport that used the Method of Characteristics (MOC) procedure of
Konikow and Bredehoeft. The modeling was performed during the FS to predict the
possible future distribution of TCE that could result from any of the various alternative
remedial actions, including the no action alternative, which were considered.
Although several sites in Area D were reportedly used for disposal of waste materials,
the source of groundwater contamination appears to bave been Site 5&39. In the area
-------
: "
Table 3. Mcehon! AFB Area D/American Lake Garden Tract Groundwater Sampling Results Total (Unfiltered).
Upgradient .M Downgradient
~
Range of Range of Mean of
Concentration" Frequency of Concentration Concentration Range of DL.s" MCL4I
Parameter (l£gll) Detection21 (pg/I) (l£g/I) (l£gll) (l£gll)
Inorganics
Aluminum 301-38,900 22/29 212-38,600 4,900 <200- < 200
Antimony BDL 0/29 N/A N/A <60-<60
Arsenic 3.1-10 4/29 12-24 18 < 10-< 10 50
Barium 27-860 2/29 333-1,280 810 < 200- <200 1,000
Beryllium 7-7 0/29 N/A N/A < 5- < 5
Cadmium 5-39 8/29 5-8 6 <5-<5 I 5
Calcium 7,610-65,100' 29/29 6,620-78,300 18,000 N/A
Chromium 1.4-67 6/29 22-103 39 < 10-< 10 100
Cobalt 11-133 1/29 92 92 <50-<50
Copper 13-244 10/29 25-131 46 <25-<25
Iron 103-155,000 26/29 107-31,300 5,500 < 100-< 100
Lead 1.7-27 12/29 5.9-78 16 <5-<5 50
Magnesium 2,740-27,800 17/29 5,180-20,600 9,000 <5,000-<5,000
Manganese 10-4,330 23/29 22-5,320 680 < 15-< 15
Mercury 1-1 0/29 N/A N/A <0.2-<0.4 2
Nickel 38-344 1/29 65 65 <40-<40
Potassium 480-8,940 2/29 5,400-5,740 5,600 <5,000-<5,000
Selenium BDL 0/29 N/A N/A <5-<5 50
Silver BDL 0/29 ,N/A N/A < 10-< 10
Sodium 4,220-34,600 22/29 . 5,04q-l,890,OOO 93,000 <5,000-<5,000
Thallium BDL 1/29 11 11 < 10-< 10
Vanadium 11-379 1/29 64 64 <50-<50
Zinc 9-297 9/29 24-152 51 <20-<20
Cyanide NA 0/17 N/A N/A < 10-< 10 i
~
-
VI
-------
Table 3. McChord AFB Area D/American Lalce Oarden Tract Oroundwater Sampling Results Total (Unfiltered). : t
Range of Mean of
frequency of Concentration Concentration Range of DLs" MCL 41
Parameter DetectionV (pg/I) (pg/l) (pg/I) (pg/I)
Volatiles
Chloromethane 16/256 0.092-1.3 0.72 <0.10-<50
Bromomethane 0/256 N/A N/A <0.10-<50
Vinyl Chloride 15/256 0.084-1.8 0.47. <0.18-<40 2
Chloroethane 3/256 0.18-0.7 0.37 <0.10-<50
Methylene Chloride 82/256 0.19-34 2.95 <0.1-<50
Acetone 8/81 8-110 39 . < 10-<50
Carbon Disulfide 12/81 2-13 4.7 < 5- < 25
1,l-Dichloroethylene (DCE) 14/256 0.075-0.80 0.39 <0.1-<5 7
1,l-Dichloroethane (DCA) 35/256 0.06-5.3 1.0 <0.07-<50
cis-l,2-Dichloroethylene (DCE) 295/657 0.08-350 20.7 <0.1-<5 70
trans-l,2-Dichloroethylene (DCE) 23/657 0.01-0.83 0.18 <0.1-<50 100
Chloroform 34/256 0.03-0.59 0.18 <0.05-<50 100 (THM)
1,2-Dichloroethane (DCA) 27/256 0.011-0.9 0.17 <0.03-< 100 5
2-Butanone 0/81 N/A N/A < 10-< 100
1,1,1- Trichloroethane (TCA) 96/256 0.02-18 0.64 <0.03-<50 . 200
Carbon Tetrachloride 1181 0.19 . 0.19 <5-<25 5
Vinyl Acetate 0/81 N/A N/A < 10-<50
Bromodichloromethane 1/256 0.09 0.09 <0.1-<50 l00(THM)
1,2-Dichloropropane 0/256 N/A N/A <0.1-<25 5
cis-l,3-Dichloropropene 0/256 N/A N/A <0.1-<25
Trichloroethylene (TCE) 354/657 0.08-120 7.8 <0.12-<5 5
Dibromochloromethane 1/256 0.27 0.27 <0.1-<25 100 (THM)
1,1,2- Trichloroethane 191256 0.02-0.9 0.14 <0.02-<50
Ben7.ene 251256 0.02-1.4 0.39 <0.1-<50 5 ~
-
-------
"
Table J. McChord AFB Area D/ American Lake Garden TraCt Groundwater Sampling Results Total (Unfiltered).
Range of Mean of
Frequency of Concentration Concentration Range of DLs" MCL~
Parameter DetectionV, (pg/I) (pg/I) (pg/I) (pgll)
Volatiles (Continued)
trans-I,3-Dichloiopropene 0/81 N/A N/A < 5- < 25
Bromoform H256 0.34 0.34 <0.1-<25 100 (THM)
4-Methyl-2-Pentanone 0/81 N/A N/A < 10-<50
2-Hexanone 0/81 5 5 < 10-<50
T etrachloroethylelie (PCE) 62/256 0.03~.52 0.10 <0.03-<50 5
Toluene 4/256 0.02-670 95.7 <0.1-<50 1,000
1,1,2,2- Tetrachloroethane 0/256 N/A N/A <0.1-<50
Chlorobenz.ene 2/256 ,0.34-:0.36 0.35 <0.1-<25 100
Ethyl benzene 9/256 0.27-100 22.5 700
Styrene 0/256 N/A N/A <0.1-<25 100
Xylenes Total 11/102 0.02-400 82 <0.1-<50 10,000
2-Chloroethyl VOiyl Ether 0/81 N/A N/A <5-<25
Semivolatiles
Phenol 0/17 N/A N/A <8-10
bis(2-Ch1oroethyl)Ether ' 0/17 N/A, N/A <; 8-10
2-Chlorophenol 0/17 N/A N/A <8-10
1,3-Dichloro~e 30/272 0.13-7.8 2.07 <0.3-50
1,4-Dichlorobeoz.eae' 14/272 0.3-5 1.05 <0.4-50 75
Benzyl AlcolIol 0/17 N/A 'N/A <8-10
1,2-Dicblorobenzene 4/272 0.35~. 79 0.57 <0.4-50 600 1
2-Methylpbeool 0/17 N/A NIA <8-10 CD
, i
.-
-------
Table J. .Mc01ord AFB Area D/American Lake Garden Tract Groundwater Sampling Results Total (Unfiltered).
Range of Mean of
Frequency of Concentration Concentration Range of DLs" MCL4I
Parameter. Detection21 (pg/l) (pg/l) (pg/l) (pg/l)
Semivolatiles (Continued)
bis(2-chloroisopropyl)Ethcr 0/17 N/A N/A. <8-< 10
4-Methylphenol 0/17 N/A N/A <8-< 10
N-Nitroso-Di'n~propylamine 0/17 N/A N/A < 8-< 10
Hexachloroethane 0/17 N/A N/A <8-<10
Nitrobenzene'. 0/17 N/A N/A <8-<10
IlIOphorone' 0/17 N/A N/A < 8-< 10
4-Methylphen~1 0/17 N/A N/A <8-< 10
2-Nitrophenol 0/17 N/A N/A <8-< 10
2,4-Dimetbylpb~ol 0/17 N/A N/A <8-< 10
Benzoic Acid 0/17 N/A N/A <40-<50
..
bis(2-chloroethoxy)Methane 0/17 N/A N/A <40-<50
2.4-DichlorOpiienol' 0/17 N/A N/A <8-< 10
1,2,3- Trichlo~benr.ene 21272 0.68-13 6.84 <0.1-<50
1,2.4- Tricbl.oiobenzene 3/272 0.51-13 5.41 <0.1-<50
Naphthalene.. 4/272 0.53-11 3.79 <0.1-<50
4-chlo~l~e'. 0/17 N/A N/A <8.< 10
Hexachlorobutadiene 31272 0.72-11 4.88 <0.1-<50
4-chloro-3-M~ylphenol 0/17 N/A N/A <8-< 10
2-Methylnaphthalene 0/17 . N/A N/A <8-< 10
Hexachloroeyctopentadiene 0/17 N/A N/A <8-< 10
2,4,6- Tri~hJorophenol 0/17 N/A N/A <8-<10
2.4,5-Trichl~henol 0/17 . N/A N/A <40-<50
2-chloronaphthalene 0/17 N/A N/A <8-<10 i
2-Nitroaniline: 0/17 N/A N/A <40-<50
\ :.
-
00
-------
Table 3. Mcehord AFB Area DI American Lake Garden Tract Groundwater Sampling Results Total (Unfiltered).
Range of Mean of
Frequency of Concentration Concentration Range of DLs" MCL~
Parameter Detectionv (pg/l) (pg/l) (pgll) (pgll)
Semiyolatiles (~tinued)
Dimethyl Phthalate 0/17 N/A N/A <8-<10
Acenaphthylenl?. 0/17 N/A N/A <8-< 10
2.6-Dinitrotoluene , 0/17 .N/A N/A <8-<10
3-Nitroanilino . 0/17 N/A N/A <40-<50
Acenaphthene 0/17 N/A N/A <8-<10
2.4-Dinitrophenol 0117 N/A N/A <40-<50
4-Nitrophenoi 0/17 N/A N/A <40-<50
Dibenzofuran 0/17 N/A N/A <8-<10
2.4-Dinitrotoluet1e 0/17 N/A N/A <8-<10
Diethylphthalate ., .0/17 N/A N/A <8-< 10
4-ChIorophenyl-phenyl Ether 0/17 N/A N/A <8-<10
Fluorene 0/17 N/A N/A <8-< 10
4-Nitroaniline : 0/17 N/A N/A <40-<50
4.6-Dinitro-2-Methylphenol 0/17 N/A N/A <40-<50
n-Nitrosodiphenylamine 0/17 N/A N/A <8-< 10
4-Bromophenyl-phenylether 0/17 N/A N/A <8-<10
Hexachloroben.r.ene. . 0/17 N/A N/A <8-< 10
Pentachlorophenol' 0117 N/A N/A <40-<50
Phenanthrene 0/17 N/A N/A <8-<10
Anthrene 0/17 N/A, N/A <8-<10 1
Di-n-Butylpbthalate 0/17 N/A N/A <8-< 10
n
Fluoranthene 0/17 N/A N/A <8-< 10
Pyrene 0/17 N/A. N/A <8-<10
'.' .-
-------
Table J. . Mcq.ord AFB Area D/American Lake Garden Tract Groundwater SampJing Results Total (Unfiltered).
Range of Mean of
Frequency of '. ,. Concentration Concentration Range of DLs" MCL4I
Parameter Dctection21 (pgn) (pg/l) (pg/l) (pgn)
Semivolatiles, (Continued)
Butylbeozylphthalate 0/17 N/A N/A < 8-< 10
3,3' -Dichlorobenzidino 0/17 N/A N/A < 16-<20
Beozo(a)Anthracene 0/17 N/A N/A <8~< 10
Chryseno 0/17 . N/A N/A <8-< 10
bis(2-Ethylhexyl)Phthalate 2/17 5-9 7 < 8-< 10
Di-n-Octyl Phthalate 1/17 20 20 <8-< 10
Beozo(b )Fluoranthene 0/17 N/A N/A < 8- < 10
Ben7.o(k)Fluoranthene 0/17 N/A N/A <8-< 10
Beozo(a)Pyrene'. 0/17 N/A N/A <8-< 10
Indeno( 1,2,3-Cd)Pyrene 0/17 N/A N/A <8-< 10
Dibenz(a,h)Antbra.cene 0/17 N/A N/A < 8-< 10
Beozo(g,h,i)Peryleno 0/17 N/A N/A <8-< 10
PestidcleslPCBs
alpha-BHC . 0/20 N/A N/A <0.01-<0.05
beta-BHC ' 0/20 N/A N/A <0.01-<0.05
deJta-BHC 0/20 N/A N/A <0.01-<0.05
gamma-BH~indane) 0/20 N/A N/A <'0.01-<0.05
Heptachlor 0/20 N/A N/A <0.01-<0.05 0.4
Aldrin 0/20 N/A N/A <0.01-<0.05
Heptachlor Epoxide 0/20 'N/A N/A <0.01-<0.05 0.2
Endosulfan I' " 0/20 N/A N/A <0.01-<0.05 i
'\ :
t-J
o
"
-------
Table 3. McChord AFB Area D/American Lake Garden Tract Groundwater Sampling Results Total (Unfiltered).
Range of Mean of
Frequency of Concentration Concentration Range of DJ..s3' MCL4I
Parameter Detection21 . (pg/I) (pg/I) (pgll) (pgll)
PesticideslPCBs (Continued)
Dieldrin 0/20 N/A N/A <0.02-<0.11
4,4'-DDE 0/20 N/A N/A <0.02-<0.11
Endrin 0/20 N/A N/A <0.02-<0.11
EndosuJ fan II 0/20 N/A N/A <0.02-<0.11
4,4'-DDD ,,' 0/20 N/A N/A <0.02-<0.11
t>,
Endosulfan Sulfate. .1\1 0/20 N/A N/A <0.02-<0.11
4,4'-DDT 0/20 N/A N/A <0.02-<0.11
Methoxychlor 0/20 N/A N/A <0.1-<0.S3 40
Endrin Ketone 0/20 N/A N/A <0.02-<0.11
Chlordane 0/20 N/A N/A <0.1-<0.S3 2
Toxaphene 0/20 N/A N/A <0.2-< 1.1 3
Aroclor-1016 0/20 N/A N/A <0.1-<0.S3 O.S
Aroclor-1221 0/20 N/A N/A <0.1-<0.S3 O.S
Aroclor-1232 0/20 N/A N/A <0.2-<0;S3 O.S
Aroclor-1242 0/20 N/A N/A <0.2-<0.S3 O.S
Aroclor-1248 0/20 N/A N/A <0.2-<0.S3 O.S
Aroclor-I2S4 0/20 N/A N/A <0;2-< 1.1 O.S
Aroclor-1260 0/20 N/A N/A <0.2-<1.1 O.S
Phorate 0/6 N/A N/A <0.20-<0.21
DisuJfoton 0/6 N/A N/A <0.20-<0.21
1
n
'\ :
I'J
-------
Table 3. McChord AFB Area D/American Lake Garden Tract Groundwater Sampling Results Total (Unfiltered).
Range of Mean of
Frequency of Concentration Concentration Range of DLs" MCL4I
Parameter DetectionV (,&g/l) (pg/l) (pglt) (pglt)
PestiddeslPCBs (Continued)
Feothion 0/6 N/A N/A <0.50-<0.53
Sutprofos(bolstar) 0/6 N/A NIA <0.50-<0.53
EPN 0/6 N/A N/A <0.50-<0.53
TEPP 0/6 N/A N/A <0.50-<0.53
Parathion 0/6 N/A N/A <0.50-<0.53
Sutfotepp 0/6 N/A N/A <0.50-<0.53
Malathion 0/6 N/A N/A < 1.0-< 1.1
Ethoprop 0/6 N/A N/A <0.30-<0.32
Parathion Methyl 0/6 N/A N/A <0.30-<0.32
Ronnel 0/6 N/A N/A <0.30-<0.32
Cblorpyrif08 Methyl 0/6 N/A N/A <0.30-<0.32
Diazino11 0/6 N/A N/A <0.50-<0.53
Thionazin 0/6 N/A N/A <0.30-<0.32
Famphur 0/6 N/A N/A <1.0-<1.1
11 Range of Concentration
2/. Frequency of Detection = number of detections/number of samples analyzed.
31 Range of DLs = range of detection limits.
41 THM "" Trihalomethanes (total)
i
~
'\ :
-------
[,.;
i
I..
I
:r
L"
!
McChord Air Force Base - Area D/ALGT
l.
I
Figure 3
TCE CONCENTRATIONS IN UNCONFINED
AOUIFER
-------
I
"'"
."""a'.'-""_AMfI
"TI
\.
McChord Air Force Base - Area D/ALGT
I
I.
Figure 4
DCE CONCENTRATIONS IN UNCONFINED
AQUIFER
-------
.
McChord AFB Area D/ALGT ROD
Page
27
concentration in the deeper aquifer zones, rather than in the vadose zone. This
phenomenon indicates that the waste material may have infiltrated through the vadose
zone and groundwater as separate phase material (dense, non-aqueous phase liquids or
, DNAPLs) to lodge on top of relatively impermeable zones. Such DNAPLs are difficult
to confirm, however, even through an extensive sampling program. The vertical extent
of contamination is limited, however, by the till separating the shallow and deeper units
of the aquifer. Samples from wells screened in the deeper Salmon Springs Aquifer
exhibit contamination at or below detection limits (1.3 ugll DCE in well DA-17c), and
the analytical results were not reproducible during successive sampling events.
2.
Surface Water and Sediment
There are a number of lakes or wetlands which are described geologically as glacial
"kettle" depressions that appear to be hydraulically connected by groundwater. Surface
water and sediment samples were obtained from these water bodies (Figure 1): Duck
Pond; Unnamed pond in ALGT; Baxter Lake; Carter Lake; Emerson Lake; Lamont
Lake; and Whitman Lake.
'Surface water and sediment samples were analyzed for VOCs, inorganics, pesticides, and
~CBs. TCE and DCE were both detected in several sud'ate. water samples, aJong With
arsenic, chromium, copper, lead, selenium, and zinc, and the pesticides dieldrin and
endrin ketone. The sediment samples showed detections of TCE and DCE, arsenic,
cadmium, chromium, copper, lead, nickel, selenium, and zinc, and ,the pesticides
chlordane, DDT, DDD, DDE, and dieldrin. Tables 4A and 4B present the frequency of
, det~tion of these contaminants in surface water and sediment, respectively.
-
"
, ,
, ,
Direct surface water ru'noff pathways for transport of soil are not known to have existed
between the potential source areas and the surface water bodies. Recharge by ,
groundwater appears to be the sole potential pathway between source areas and surface
\Vater~ Consequently, the elevated levels of.inotganics within the surfClce , '
, waters/sediments were determined to be caused by' naturally occurring inorgariics both in
the groundwater and local geologic formations. Similarly, as pesticides were not found ..
in the groundwater, the low levels of pesticides found in the sediments were attributed to
-------
Table 4A. ,McChord AFB Area DI American Lake Garden Tract. Surface Water Sampling Results. ,
-, Ambient Water Quality Criteria
(ugll)
, '
, ~ange of ~ Mean of
, , ~requencyll
Concentration Concentration Range of DlS'
Parameter' , of Detection (ugll) " (ug/l) (ug/l) Acute Chronic
Volatiles (U,1K2)
Trichloroethylene (TCE) 7/12 0.06-1.2 ' 0.41 <.0.12-<0.12 45,660. 21,900.
cis-I.2-dichloroethylene , " 4/21 0.07,-1.8, 0.80 <0.1-<0.1 11,600'/.
trans-l.2-d~ch1oroethylene" J 0/21 N/A N/A 11,600". I
<0.1-<0.1
'i
Dissolved Metals CU2/h) ,I~I
antimony 0/17 'N/A' N/A <3.4-<3.4 9,000. 1,600.
arsenic 7/17 3.4-6:3 4:6 <3.3-<3.3 360 (tri) 190 (tri)
beryllium, 0/17 N/A' N/A < 1.6- < 1.6 130. 5.3+
cadmium:' 0/17 N/A" N/A <2.8-<2.8 3.9+ 1.1+
chromium (h~x) 0/17 N/A' N/A < 10-<50 16 (hex) 11 (hex)
chromium (total) 8/17 2;4-:4.3 3.2 <2.2-<2.2 17oo+(tri) 210+ (tri)
"
copper " 1/17 29, ' 29 < 10-< 11 18+ 12+
lead 8/17 2.6-6.2, ' 3.8 < 1.5-< 1.5 83+ 3.2+
mercury 0/17 N/A N/A <0.08-<0.08 2.4 0.012 1
nickel 0/17 N/A: N/A <22-<22 1,400+ 160+
o
selenium' , 1117 ' 3.9 3.9 <2.6-<2.6 20 5.0
silver 0/17 N/A. N/A <2.5-<2.5 4.1+ 0.12
, thallium ' 0/17 N/A' N/A <3.5-<3.5 1,460. 40.
zinc ,; 16/17 24-220 :' 75 <4.6 '120+ 110+
t-.)
00
" :
.
-------
Table 4A. McChord AFB Area DI American Lake Garden Tract. Surface Water Sampling Results.
Ambient Water Quality Criteria
(ugn)
. Range of Mean of
Frequency" Concentration Concentration . Range of DLs"
Parameter of Detection (ug/I) (ug/I) (ug/I) Acute Chronic
Pesticides (UIlIkIZ)
aldrin 0/14 N/A N/A <0.002-<0.03 3.0
chlordane . 0/14 N/A N/A ' <0.025-<0.35 2.4 0.0043
4,4'-DDT . 0/14 N/A N/A <0.004-<0.06 1.1 0.001
4,4'-DDD . 0/14 N/A N/A < 0.004- < 0.06
4,4'-DDB 0/14 N/A N/A <0.004-<0.06 1,050.
dieldrin 4/14 0.006-0.007 0.006 <0.004-<0.06 2.5 0.0019
endosulfan I 0/14 N/A N/A <0.004-<0.06 0.22 0.056
. endosulfan.1 0/14 N/A N/A <0.004-<0.06 0.22 0.056
endosulfan sUlfate 0/14' N/A N/A <0.01-<0.14
endrin 0/14 N/A N/A < 0.004- < 0.06 0.18 0.0023
endrin ketone. 1/14 0.004' 0.004 <0.004-<0.06
alpha-BHC 0/14 N/A N/A <0.002-<0.03
beta-BHC 0/14 N/A ,. N/A <0.002-<0.03
. delta-BHC . .: 0/14 N/A N/A <0.002-<0.03
gamma-BHC (lindane) 0/14 N/A N/A <0.002-<0.03 2.0 0.08
heptachlor 0/14 N/A N/A <0.002-<0.03 0.52 0.0038
heptachlor epoxide 0/14 N/A N/A <0.002-<0.03 0.52 0.0038
methoxychlor: 0/14 N/A N/A <0.05-<0.070 0.03 i
toX8phen~ 0/14 N/A N/A <0.05-<0.070 0.73 0.0002 (D
, :
N.
-------
Table 4A. MeChard AFB Area DI American Lake Garden Tract. S\lrface Water Sampling Results.
Ambient Water Quality Criteria
(ugll)
Range of Mean of
. Frequencylf Concentration Concentration . Range of DUV
Parameter. of Detection (ug/1) . (ug/1) (ug/1) Acute Chronic
PCBs (kllm 2.0 0.014
arcolor-l016 0/14 . N/A N/A <0.05-<0.70
aroclor-1221 0/14 N/A . N/A < 0.05- < 0.70
aroclor-I232 0/14 N/A N/A <0.05-<0.70
aroclor-1242 . 0/14 N/A N/A <0.05-<0.70
aroclor-1248 0/14 'WA N/A <0.05-<0.70
aroclor-I2S~ 0/14 N/A N/A <0.1-< 1.4
aroclor-l260 0/14 'N/A N/A <0.1-< 1.4
1/ Frequericy of Detection .;. Dumber of detections/number of samples analyzed
21 Range of DLs = range of detection limits ..
3/ Criteri,is not i~mer specific. Value.given for unspecified dich1oroethylenea.
. Insufficient data to develop criteria. Value presented is LOEL (Lowest Observed Effect Level)
+ Hardri~ Dependent Criteria (100 ugll Caco, used) . .
'\ :
..
1
n
("J
o
-------
Page
31
Table 4B. McChord AFB Area DI American Lake Garden Tract.
Sediment Sampling Results. .
Frequencyll Range of Mean of Range of
Parameter of Detection Conceatratioo Concentration Dtr'
...
. Volatiles (U21k,)
Trichloroethylene (I'CE) 12112 0.77-40 12 N/A
cis-l ,2-dichloroethylene 1/12 2.3 2.3 <0.1-<2.27
trans-I ,2-dichloroethyleue 0/12 N/A N/A <9.1-<2.27
Dissolved Metals (U21k2)
antimony 0/17 N/A N/A < 1.2-<4.8
arsenic 14/17 2.7-8.5 5.3 <2.5-<4.1
beryllium 0/17 N/A N/A <0.7-<2.3
cadmium 1/17 3.1 3.1 <1.0-<4.0
chromium (total) 17/17 7.7-48 2S N/A
copper 4/17 16-170 66 <4.5-<16
lead 15/17 2.5-318 77 < 1.2- < 1.9
mercury .0/17 N/A N/A <0,1-<0.7
nickel 2/17 55-86 70 <7.8-<31
selenium 5/17 2.6-4.4 3.3 <0.9-<3.7
~ver 0/17 N/A N!A <0.9-<3.5
thallium 0/17 N/A N/A < 1.2-< 5.0
zinc 8/17 9-124 60 <3.4-<6.5
Pesticides (uszlksz)
aldrin 0/17 N/A N/A ' <3.1-< 14
chlordane 1/17 650 650 <31-< 140
4,4'-DDT 3/17 49-150 100 <6.1-<24
4,4'-DDD 1/17 380 380 <6.1-<24
4,4':-DDE 1/17 61 61 <6.1-<24
cJjeldrin' 1/17 15 15 . <.61-<28
endosulfan I 0/17 N/A N/A <4.1-< 14
. .
endosulfan n 0/17 N/A N/A <6.1-<28
endosulfan sulfate 0/17 N/A NiA <6.1-<:28
endrin 0/17 N/A N/A <6.1-<28
en~~ keto~e . 0/17. N/A N/A <6.1-<28
'" .' .
alpha-BHC 0/17 N/A N/A <3.1-< 14
beta-BHC 0/17 N/A N/A <3.1-< 14 ....
delta-BHC 0/17 N/A N/A <3.1-< 14
gamma-BHC (lindane) 0/17 N/A N/A <3.1-< 14
heptachlor 0/17 N/A N/A <3.1-< 14
-------
Table 4B. McChord AFB Area DI American Lake Garden Tract.
Sediment Sampling Results.
Page
Frequency.' Range of Mean of Range of
Parameter of Detection Concentration Concentration DIE'
methoxychlor 0/17 N/A N/A <31-<140
toxaphene 0/17 N/A N/A <61-<280
PCBs (U2/k2)
arcolor-l016 0/17 N/A N/A <34-<140
aroclor-I221 0/17 N/A N/A <34-<140
aroclor-I232 0/17 N/A N/A <34-<140
aroclor-1242 0/17 N/A N/A <34-<140
aroclor-1248 0/17 N/A N/A <34-<140
aroclor-l2S4 0/17 N/A N/A <61-<280
aroc1or-l260 0/17 N/A N/A <61-<280
1/ Frequency of Detection = number of detections/number of samples analyzed
21 Range of DLs = range of detection limits
N/A Denotes not applicable
.." .
.
32
..
-------
McChord AFB Area DI ALGT ROD
Page
33
3.
Soil
Soil contamination was investigated in suspected source areas through a successive
. process of soil gas surveys followed by borings and soil sampling and analyses. Soil gas
samples were taken at 350 locations in Sites 4,5&39, 6, and 7, and several subareas of
Site 26. Survey results were used on a qualitative basis to locate 29 soil boring locations
in the areas exhibiting the highest levels of soil gas. The source-area soil borings were
drilled to depths between 7.5 and 37.5 feet in the seven waste disposal sites. The soil
samples were analyzed for VOCs, SVOCs, pesticides, PCBs, and inorganics. In
addition, the soil boring taken at Site 35 was analyzed for radioactive parameters. Table
5 summarizes the RI soil sampling data.
,
8.
Organic and Inorganic Compounds
The primary contaminants, TCE: and DCE, were found at concentrations up to 881 ug/kg .
. .
. (micrograms per kilogram) and 81 ug/kg respectively, in samples of waste materials
obtained from Site 5&39 and Site 7. Several other VOCs were also detected, including
.' PCE, 1,1,2,2-Tetrachloroethane,b~nzene, ethylbenzene, tpluene, and xylenes (th~ BETX
. .cOmpounds characteristic of fuel products); 1, i - DCE~ and 1,4- DichlorobenZene. Seven
.. Pesticides (beta and delta BHCs, DDD, DDE, and DDT, dieldrin, and chlordane) ahd six
inorganics (arsenic, barium, cadmium, lead, mercury, and vanadium) were also detected.
The levels of contamination were evaluated in the baseline risk assessment for both
protection of human health (e.g., direct contact under the residential ~nario) and the
environment (e.g., groundwater protection).
-: .~?
Twenty-seven area background soil Samples' ~~ie coll~ted within the boundarieS of .
McChord AFB in areas with: (1) similar geomorphology; and (2) no known or suspected
waste disposal activities. Inorganic results for background soils are found in Table 6.
All samples were analyzed for the 23 Target Compound List metals. Based on a
. .statistica1.comparison., .the inorganic' concentrations ~ound wi.thin 'Ar.ea:Dwere .~ound to ~ .'.
. . 'coiisistent with the area background inorganic concentrations. . .
....
Six groundwater monitoring wells installed upgradient of Area D were sampled for
inorganic contaminants. The contaminant concentrations, with the exception of Thallium,
were determined to be consistent with the area background concentrations. Thallium was
noted in a split sample at a concentration above the detection limit. The quality
-------
.
Table S. MeChord AFB Area DI American Lake Garden Tract Soil Sampling Results. Page 34
Range of Mean of
Frequency of Concentration Concentration Range of DIr'
Parameter Detection II (,tglkg) (,tglkg) (,tglkg)
Inorganics
Aluminum 8/8 8,090-23,500 13,761 N/A
Antimony 0/8 N/A N/A <12-<17
Arsenic 8/8 2.9-8.6 4.8 N/A
Barium 7/8 4.4-128 66.3 <55
Beryllium 0/8 N/A N/A < 1-< 1.4
Cadmium 2/8 1.2-4.7 3.0 <1-<1.4
CaJcium 8/8 1,990-3,590 3,049 N/A
Chromium 8/8 15-21 18.1 N/A
Cobalt 0/8 N/A N/A <10-<14
Copper 7/8 14-31 22 <16
Iron 8/8 8,270-19,700 15,971 N/A
Lead 8/8 3.4-86 17.4 N/A
Magnesium 8/8 2,230-5,520 4,096 N/A
Manganese 7/8 199-584 299 <3.4
Mercury 4/8 0.15-1.9 1.2 <0.1-<0.11
Nickel 8/8 16-32 27.8 N/A
Potassium 0/8 N/A N/A < 1,040-< 1,380
Seleniuni . 0/8 N/A. N/A . .,< 1-< 1.4
'.
Silver 0/8 . N/A N/A . <2.1-<2.8
Sodium N/A ' . N/A < 1,040-<1,380
0/8
Thallium 0/8 N/A N/A <2.1-<2.8
Vanadium 8/8 23-41 34 N/A
Zinc 8/8 27-64 40.5 N/A.
Cyanide 0/8 N/A N/A <1-<1.4
Volatiles
Chloromethane 0/55 N/A N/A <0.083-2,889
Bromomethane 0/55 N/A N/A <0.1-2,889 .
Vinyl Chloride 0155 N/A N/A <0.19-2,889
ChJoroethane 0/55 .~/A. N/A < 0..54-2,889
" .' . . ..' <6-<'1;445 .
Methylene' Chloride 50/54 1.3.-490 .37.8
-------
'Table S. Mcehord AFB Area D/American Lake Garden Tract Soil Sampling Results. Page 3S
Range of Mean of
Frequency of Concentration Conceatration Range of DLs"
Parameter Detection" (pglkg) (pglkg) (pglkg)
Volatiles (Continued)
Acetone 17/21 16-1,100 489 < 11-<2,889
Carbon Disulfide 0/55 .N/A N/A <6-< 1,445
1,l-Dichloroethylene (DeE) 11/55 0.11-11 2.7 <0.1-< 1,445
1,l-Dichloroethane (DCA) 2/55 0.49-0.78 0.64 <0.073-< 1,445
cis-l,2-Dichloroethylene (DeE) 34/105 0.06-81 9.18 <0.01-< 149
trans-l,2-Dichloroethylene (DCE) 1/55 0.66 0.66 <0.1-< 1,445
Chloroform 3/55 0.047-0.24 0.135 <0.052-<1,445
1,2-Dichloroethane (DCA) 5/55 0.041-4.4 1.1 <0.031-1,445
2-Butanone 4/18 110-210 148 < 11-<2,889
1,I,I-TrichloroethaDe (TCA) 27/55 0.05-2 0.36 <0.1-< 1,445
Carbon Tetrachloride 0/55 N/A N/A <0.12-1,445
Vinyl Acetate 0/55 N/A N/A <0.1-<2,889
Bromodichloromethane 1/55 0.1 0.1 <0.10-<1,445
1 ,2-Dichloropropane 4155 0.07-2.2 0.74 <0.042-< 1,445
Trichloroethylene (TCE) 94/105 0.09-881 34.1 <0.12-<:1,445
Dibromochloromethane 2/55 0.11-0.16 . 0.135 <0.094-< 1,445
1,1,2- Trichloroethane 0/55 N/A N/A <0.021-< 1,445
Benzene 10/55 . . 0.15-22 4.68 . <0;20-,< 1,445
trans-I ,3-Dichloropropene 0/55 . N/A N/A <0.37-< 1,445
Bromoform 0/55 N/A N/A <0.1-<1,445
4-Methyl-2-Pentanone 5/21 6.6-1,900 847 <0.1-<2,889
2-Hexanone 4/21 18-1,400 508 <0.1-<2,889
Tetrachloroethylene (PCE) 2S/55 0.026-130 12.6 <0.031-<1,445
Toluene 19150 0.24-11,000 1,062 <0.21-< 1,445
1,1,2,2-Tetrachloroethane 5/55 3.0-240 92.2 <0.03-< 1,445
Chlorobenzene 9/S5 0.1-660. 4.8 <0.21-< 1,445
Ethyl benzene 15/53 0.2-3,500 394.8 <0.21-< 1,445
StyreDe 2135 4-9.3 6.6 <0.1:.<1,445'
Xylenes Total 11/23 0.2-17,000 2,452 <5-<6
2-Chloroethyl Vinyl ether 1/55 0.16 0.16 <0.14-< 1,445
TricbJorofluoromethane .' 2/20 . '" 6-9 7.5 <0.1-<1,445.
l,2-Pentanone 0/3 N/A N/A <0.1
-------
«
Mcehord AFB Area D/American Lake Garden Tract Soil Sampling Results. Page 36
Table S.
Range of Mean of
Frequency of Concentration Concentration Range of DLfiZ'
Parameter Detectionll (,£glkg) (,£glkg) (,£glkg)
Volatiles (Continued)
1,2,3- Trichloropropane 0/3 N/A N/A <0.1
n-Propylbenzene 3/5 1-7.7 4.4 <0.1
1,3,5- Trimethylbenzene 4/5 6.5-209 87.6 <0.1
1,2,4- Trimethylbenzene 5/5 0.7-355 107.5 <0.1
sec-Butylbenz.eoe 3/5 0.6-4.4 2.1 <0.1
p-Isopropyltoluene 4/5 1.3-647 187.1 <0.1
n-Butylbenzene 0/5 N/A N/A <0.1
Bromochloromethane 0/2 N/A N/A <0.1
tert-Butylbenzene 1/5 1.2 1.2 <0.1
Semivolatiles
Phenol 0/8 N/A N/A <364-<1,800
bis(2-ChJoroethyl)Ether 0/8 N/A N/A <364~
-------
"Table 5. McChord AFB Area D/American Lake Garden Tract Soil Samp}4tg Results. Page 37
Range of Mean of
Frequency of CoDceotration Concentration Range of DIG'
Parameter Detection" (Jlglkg) (Jlglkg) (Jlglkg)
Semivolatiles (Continued)
4-ChJoroaniline 0/8 N/A N/A <364-<1.800
Hexachlorobutadiene 0/8 N/A N/A <364-<1.800
4-ChJoro-3-Methylphenol 0/8 N/A N/A <364-< 1.800
2-Methylnaphthalene 1/8 82S 82S ' <364-< 1.800
Hexachlorocyclopentadiene 0/8 N/A N/A <364-<1.800
2,4.6- Trichlorophenol 0/8 N/A N/A <364-< 1,800
2,4.5- Trichlorophenol 0/8 N/A N/A < 1.822-<9.200
2-Chloronaphthalene 0/8 N/A N/A <364-< 1.800
2-Nitroaniline 0/8 N/A N/A < 1.822-<9.200
Dimethyl Phthalate 0/8 N/A N/A <364-< 1,800
Acenaphthylene 0/8 N/A N/A <364-< 1.800
2,6-Dinitrotoluene 0/8 N/A N/A < 1.822-<9.200
3-Nitroaniline, 0/8 N/A N/A < 364- < 957
Acenaphthene 1/8 91 91 < 1.822-<9.200
2,4-Dinitrophenol 0/8 N/A N/A < 1.822-<9.200
4- Nitrophenol 0/8 N/A N/A <364-< 1,800
Dibenz.ofuran 0/8 N/A N/A <364-< 1.800
2,4-Dinitrotoluene '0/8 N/A N/A ' '<364-<1.800
Di~tbylphiha1ate ' 0/8 N/A N/A < 364-,< 1;800
4-Chlorophenyl-phenyl Ether 0/8 N/A N/A <364-< 1.800
Fluorene 1/8 125 125 < 364-<957
4-Nitroaniline 0/8 N/A N/A < 1.822-<9.200
4,6- Dinitro-2-Methylphenol 0/8 N/A N/A < 1.822-<9.200
D-Nitrosodiphenylamine 0/8 N/A N/A <364-<1.800
- -.. 4-Bromophenyl-phenylether 0/8 N/A N/A . <,364-< 1;800
Hexachlorobenzene 0/8 N/A N/A < 364- <: 1..800 .
Pentachlorophenol 0/8 N/A N/A < 1.822-<9.200
Phenanthrene 1/8 305 305 < 364- <957
Anthrene 0/8 N/A N/A <364-<1.800
~i-D-Butylphthalate 1/8 805 80S < 364-< 957
Fluol1lDthene' 0/8' "N/A N/A', '~,364-< 1.800
Pyrene 0/8 N/A N/A <364-<1,800 ..
...
-------
c
Table 5. McChord AFB Ami D/American Lake Garden Tract Soil Sampling Results. Page 38
Range of Mean of
Frequency of '. Concentration Concentration Range of DIG'
Parameter Detection!1 (J£glkg) (J£glkg) (,tglkg)
StmivOJatiJfS (Continued)
3,3' -Dichlorobenzidine 0/8 N/A N/A <729-<3,700
BeOzo(a)Anthracene 0/8 N/A N/A <364-<1,800
Chrysene 0/8 N/A N/A <364-< 1,800
bis(2-EthyJhexyl)Phtbalate 3/8 88-340 246 <364-<1,800
Di-n-Octyl Phthalate 1/8 200 200 <364-<957
Benzo(b )F1uoranthene 0/8 'N/A N/A <364-< 1,800
Benz.o(k)F1uoranthene 0/8 N/A N/A <364-< 1,800
Benzo(a)Pyrene 0/8 N/A N/A <364-< 1,800
Indeno(l,2,3~)Pyreoe 0/8 N/A N/A <364-< 1,800
Dibenz(a,h)Anthracene 0/8 N/A N/A <364-< 1,800
Benzo(g,h,i)Perylene 0/8 N/A N/A <364-< 1,800
n-Nitroso-di-methylamine 0/8 N/A N/A <364-< 1,800
Aniline 0/8 N/A N/A <364-< 1,800
1,2-Diphenyl Hydrazine 0/8 N/A N/A <364-<1,800
Benzidene 0/8 N/A N/A <364-<1,800
PesticideslPCBs
.a1pha-BHC 0/8 N/A N/A . <8.3:-< 11
~"'BHC ..3/8 9.2-19 13 <8.3-<11
delta-BHC 1/8 13 13 < 8.3':<: 11
gamma-BHC(Lindane) 0/8 N/A "N/A <8.3-<11
Heptachlor 0/8 N/A N/A <8.3-< 11
Aldrin 0/8 N/A N/A < 8.3-< 11
Heptachlor Epoxide 0/8 N/A N/A <8.3-<11
Endosulfan I 0/8 N/~ N/A <8.3-< 11
Dieldrin 1/8 49 49 < 17-<22
4,4'-DDE 118 79 79 < 17-<22 .
Endrin 0/8 N/A N/A < 17-<22
Endosulfan n 0/8 N/A N/A < 17-<22
4,4'-DDD 2/8 3742 37 < 17-<22
." ". Endosulfan Sulfate 0/8 . . N/A. N/A . ~11-~2Z
. .
4,4'-DDT 1/8 37 3~ < 17-<22.
-------
Page 39
Table S. McChon! AFB Area D/ American Lake Garden Tract Soil Sampling Results.
Range of Mean of
Frequency of Concentration CooceDtration Range of DIE'
Parameter Detectionlf (J£glkg) (J£glkg) (J£glkg)
PesticideslPCBs (Continued)
Methoxychlor 0/8 N/A N/A <83-<110
Endrin Ketone 0/8 N/A N/A < 17-<22
Chlordane 1/8 1/60 1/60 <83-<110
Toxaphene 0/8 N/A N/A <170-<220
Aroclor-l016 0/8 N/A N/A <83-< 110
Aroclor-I221 0/8 N/A N/A <83-< 110
Aroclor-I232 0/8 N/A N/A <83-<110
Aroclor-1242 0/8 N/A N/A <83-< 110
Aroclor-1248 0/8 N/A N/A <83-< 110
Aroclor-I254 0/8 N/A N/A <170-<220
Aroclor-1260 0/8 N/A N/A < 170-<220
11 Frequency of Detection = number of detections/Du~ber of samples analyzed.
2/ Range of DLs = range of detection limits.
~ .
,
-------
..
: TABLE 6
INOROANIC. RESULTS FOR BACKGROUND SOILS
. (mg/kg)
Constlluent AI. Sb AI BI Be Cd C. Cr Co Cu F. Pb Mg M'I Hg HI K S. Ag HI TI V Zn
Locallon Det. Simpled ,
269qO <2.0 .. 6.3
B
-------
McChord AFB Area DI ALGT ROD
Page
41
inaccurate. This determination is further supported by the ubiquitous presence of the
contaminants throughout the Area D/ALGT groundwater.
..
A modeling approach was used to evaluate the likely contaminant fate and transport from
the unsaturated to the saturated zone. For example, using the maximum concentrations of -.
TCE found in soil borings, along with a soil organic carbon of 30 percent and the
partitioning coefficient (KoJ for TCE of 112 liters per kilogram, a conservative leachate
concentration of 4 ugn was calculated. This concentration, which does not exceed the
MCL of 5 ugn for TCE, assumes conservatively that: (1) the infiltrating water is in
contact with the unsaturated zone long enough to obtain equilibrium; (2) this leachate
seeps directly into the groundwater; and (3) is not diluted once it reaches the
groundwater..
Based on modelling results, and soil and groundwater analytical data, it appears that most
VOC soil contamination has moved. to the groundwater. Residual VOC soil .
~ntamination has likely volatilized out of the soil (where it would have been rapidly
photooxidized) and contaminants are not continuing to leach .out of the soils. This
.assumption is supported. by the fate. ~d transpOrt analysis and the fact ~at the highest
plume co.ncentration$ are found at a depth of 40 to 50 feet within ~e aquifer. The .
. organics. may. have percolated through the unsaturated and saturated zones as a .separate
phase material (DNAPLs) to eventually locate on top of the . relatively impermeable zones
(e.g., till units) within the aquifer. The DNAPLs may continue to act as 8secondary
sources" of groundwater contamination, slowly releasing contamiJ:lation into the
groundwater through dissolution.
b.
Ordnance
Historically, McChord AFB ordnance has been transferred to Fort Lewis for disposal.
However, limited ordnance disposal occurred sporadically at Site 26 between the mid-
J940s to the. mid-196Qs~ .' . . .' .0. . '. . ., .
Most of the material disposed of at Site 26 was detonated with a surplus charge sufficient""
to completely oxidize the following ordnance explosives and propellants and their casings:
nitrocellulose (gunpowder), 2,4,6-trinitrotoluene (TNf)~ and hexahydro-l,3,5-trinitro-5-
trialine (RDX). The ordnance disposal method (i.e., open detonation) used generally
ensured complete destruction of the explosive materials. Ordnance was stacked in a
-------
McChord AFB Area DI ALGT ROD
Page
42
excess charge would convert the explosive compounds in the resulting fireball into
primary oxides of hydrogen, nitrogen, and carbon.
A geOphysical survey was conducted for residual debris remaining from ordnance
disposal. Ordnance material found included .30 and .50 caliber blank ammunition, nose
fuses for 2.75 high explosive MK-l warheads, spent .50 caliber bullets, one 30 mm
cannon casing, several grams of explosive material loose in the soil, and other metal
debris such as small cans and drums. The small quantity of material recovered appears
to confirm the assumption of complete destruction, and the impact of any residues is
presumed to be insignificant.
c.
Radionuclides
So1) and groundwater samples collected in vicinity of Site 35 were analyzed for residual
contamination resulting from well disposal of low-level radioactive wastewater. Samples
were analyzed for the following radioactive parameters: gross alpha, gross beta, and
gamma ray scan. Results of the soil and groundwater analyses are presented in Table 7.
Each of the radioactiye isotopes identified is a naturally occurring link" in the degradation
chains: Potassium 40, Thorium (Th)228 and 232, and Radium (Ra)"226. "1be reported"
levels of Ra 226, which "along With Krypton(Kr)' 85 and Strontium (St) 9O,werereporte4
as possibly disposed at Site 35, could "not be Compared to any readily available
background level. However, the levels are below the EP A cleanup standard of 5
picocuries per gram for inactive uranium processing sites (40 CFR 192.12).
VI. SUMMARy.oF SITE RISKS
The baseline risk assessment considered both human health and ecological risks. Therisk "
evaluations were prepared in accordance with EPA's Risk Assessment Guidance for
Superfund (RAGS) and EPA Region 10 Exposure Parameters (dated January 31,1990).
: The results" of the b,uman h~th ri~~ assessment are (jiscussed belo~. " "
A.
Human Health Risks
Adverse effec~ resulting from exposure to chemical contaminants are identified as either
carcinogenic (Le., causing the development of cancer in one or more tissues or organ
systems) or noncarcinogenic (i.e., direct toxic effects on organ systems, reproductive and
.
-------
Table 7.,. Results of Radiological Analyses
Radionuctide (gamma scan):
Gross Cs 137 Ra 226 K40 Th 228 Th 232
Sample Depth (ft) Alpha Gross Beta
WATER (PCi/l)
DB.II-l 0 +/- 1 0 +/- 2 <14
DB. H -2 0 +1- I 0 +1- J <9
..
SOIL (PCilg)
DB-II-I-1 2.5-4 . 5 +/- 3 16 +/- 3 <0.1 0.29 +/.0.06 5.2 +/- 0.6 0.38 +/.0.03 0.32 +/- 0.02
DB-II-I-2 . (dup) 3 +1- 2 12 +/- 4 <0.1 0.4 +I- 0.1 8.2 +1- 0.1 0.6 +1- 0.1 0.3 +1- 0.2
DB-11-2 7.5-8.5. 0 +/- 5 . 11 +/- 4 <0.1 0.44 +/- 0.06 8.2 +/- 0.7 0.42 +/- 0.04 0.4 +/- 0.2
DB-I 1-3 12:5-14.5 0 +/- 4 15 +/- 5 <0.1 0.5 +1- 0.1 9.4 +/- 1 0.57 +1- 0.06 0.55 +/- 0.02
DB-I 1-4 17.5-18 7 +1- 2 12 +/- 5 <0.1 0.5 +/- 0.1 11 +/- I 0.64 +/- 0.07 0.5 +/- 0.2
DB-I1-5 27.S-29.5 0 +/- 3 10 +/- 2 .<0.1 0.32 +1- 0.06 7.4 +1- 0.7 0.41 +/- 0.04 0.4 +/- 0.1
Mean: 2.5 +1- 6.0 12.7 +1- 4.7 <0.1 0.41 +/.0.18 8.2 +1- 3.9 0.50 +/- 0.23 0.41 +1- 0.20
RINSA TE
BLANK (PCill)
RB-It-I 9 +1- 4 0 +1- 4 <53
Note: Range shown ill plus or minull (+/-) two standard deviations. :I
CD
, :
~
-------
McChord AFB Area DI ALGT ROD
Page
developmental effects). In the baseline risk assessment, risks have been estimated for
both current use and future residential land use at Area D and the ALGT. The human
receptors considered were off-site and on-site residents, on-site workers, and on-site
visitors. Exposure conditions for these receptors were assumed to correspond to a wide
range of activities including residential, recreational, and industrial work associated with
Area D and the ALGT.
1.
Chemicals of Concern
Data collected during the RI were used to identify chemicals present at the site. Media
sampled included groundwater, soils, surface water, and sediments. All chemicals were
included in the assessment unless a) they were not detected in any of the above media; b)
toxicity reference values (Le., Reference dose [RIDs] or cancer slope factors) have not
been developed for a chemical; or c) the chemical was identified as an essential nutrient.
The exception to the above criteria was chemicals that were detected in at least one
medium for at least one site allowing for the possibility of migration between media.
These chemicals were included in the risk assessment at a concentration equal to half of
their respective detection limits (RAGS guidance, 1990).
Out of 129Con~an~ for which. .analysis waS .conducted ~ Area D exposure medi~, 77
chemicals. were meaSured above their respective detection limits. .Of these 77 chemicals,
18 were determined in the risk assessment to be contaminants of concern (COCs) for the
receptors listed above (See Tables 8 and 9). In this case, COCs are defined as those with
potential exposures presenting a carcinogenic risk of greater than 1 x 10-6 (one chance of
excess cancer in a population of one million) or a noncarcinogenic hazard index greater
than a value of one. Table 8 lists chemicals inCluded in the baseline risk assessment.
based on the RI data and above screening data.
. .. .,
Four of the COCs are known human carcinogens (benzene, vinyl chloride, ar~nic, and
chromium), eight are probable h.uman carcinogens. (dieldrin, methylene chloride,
. trichloiQethyl~ne, ..styrene, : 1 ,2':dich~oroethane; 4,~-DDT,. chlQrdane, arid: .
bis(2-ethylhexyl)phthalate) and three are possible human .carcinoge~s
(1,I-dichloroethylene, 1, I-dichloroethane, and beta- BHC).
.
44
,.
-------
Table 8.. Chemicals included in the Baseline Risk Assessment.
Surface
. . . Soil Groundwater Water Sediment Air
InorganlCs
Aluminum X X N/A N/A N/A
Arsenic'. X X N/A N/A N/A
Barium X N/A N/A N/A
Cadmium X X N/A N/A N/A
Calcium' X' X N/A N/A N/A
Chromium X' X N/A N/A N/A
Cobalt _If. . N/A N/A N/A
Copper X N/A N/A N/A
Iron X X N/A N/A N/A
Lead . " X X N/A N/A N/A
Magnesium X X N/A N/A N/A
Manganese X X N/A N/A N/A
Mercury X N/A N/A N/A
Nickel X N/A N/A N/A
Potassium N/A N/A N/A
Sodium X N/A N/A N/A
Thalliumv N/A N/A N/A
Vanadium. X N/A N/A N/A
Zinc X X N/A N/A N/A
Organics
Tetrachloroethylene (PCE) X X N/A N/A X
I, 1,2,2- Tetrachloroethane X N/A N/A X
Trichloroethylene (TCE) X X X X X 1
t, t.t-Trichloroethane (TCA) X X N/A N/A X
CD
1,1 ,2-Trichloroethane (TCA) X N/A N/A X
l.l-Dichloroethane (DCA) X X N/A N/A X
l ,2:Dichloroethane (DCA) :. X X N/A N/A X
'\; ~
VI'
-------
Table 8. Chemicals included in the Baseline Risk Assessment.
Surface
Soil Oroundwater Water Sediment Air
1, 1-Dicbloroethylene (DCB) X X N/A N/A X
cis-l',2-Dicbloroethylene (cDCE) X X .X X X
trans-1,2-DCB (tDCE) X X N/A N/A X
Vinyl cbloride (cbloroethylene) X N/A N/A X
Chloromethane (methyl cbloride) X N/A N/A X
Methylene Cbloride (dichloromethane) X X N/A N/A X
Cbloro~o~ (tricbloromethane) X X N/A N/A X
Dibromochloromethane X N/A N/A X
BromOchloromethane X N/A N/A X
TrichlOroftuoromethane X N/A N/A X
I ,2-.Dichloropropane X N/A N/A X
1,2,3- 'tricbloropropane X N/A N/A X
Benezene X X N/A N/A X
Bthylbenzene X X N/A N/A X
Toluene X X N/A N/A X
Xylenes (total). X X N/A N/A X
Cblorobenzene X X N/A N/A X
I ,2-Dicblorobenzene X X N/A N/A X
I ,3-Dichlorobenzene X X N/A N/A X
I ,4-Dichlorobenezene X X N/A N/A X
I ,3,S- Trimethylbenzene X N/A N/A X
I ,2,4- Trimethylbenzene X N/A N/A X
Styrene X N/A N/A X
Jsopropylbenzene X N/A N/A X
n-propylbenzene X N/A N/A X
sec-But)'lbenzene X N/A N/A X 1
tert-B~t)'lbenzene X N/A N/A X
n-Butylbenzene X N/A N/A X ~
p-isoprj)pyltoluene X X N/A N/A
, ~
.
0'1
-------
Table 8. Chemicals, included in the Baseline Risk Assessment.
Surface
Soil Groundwater Water Sediment Air
Carbon disulfinde X N/A N/A X
Acetone X X N/A N/A X
2-Butanone (Methylethylketone, MBK) X N/A N/A X
4~Methyl-2-penthanone (MmK) X N/A N/A X
2-Hexanone (butylmethylketone) X N/A N/A X
Naphthale~ X N/A N/A X
2-Methylri~phthalene X N/A N/A X
Acenap~thene X N/A N/A X
Fluorene X N/A N/A X
Phenanthrene X N/A N/A X
2-chloroethyl-vinyl-ether X N/A N/A X
Di-n-butylphthalate X N/A N/A X
bis (2-ethylhexyl) phthalate X N/A N/A X
Di-n-Octylphthalate . X N/A N/A X
4-Methylphenol X N/A N/A X
Benzoic Acid X N/A N/A X
Beta BHC X N/A N/A X
Delta BHC. X N/A N/A X
Chlorodane X N/A N/A X,
Dieldrin X N/A N/A X
4,4' DDT X N/A N/A X
4,4' DDD " X N/A N/A X
4,4' DDE. X N/A N/A X
II ,This. chemical was analyzed for, but was not found above detection levels for this medium.
21 -'.Thallium was not detected in groundwater wells used for computing exposure point concentratioDB; however, it was detected in a single sample (out of
28) from another well. .
NI A Denotes not applieable. .
. Denotes that cllemical was analyzed for but not found above detection limit.
X Denotes the chemicKls included in the Baseline Risk Assessment.
z
CD
'\ :
".
-------
Table ,. Pathways Evaluated for the Reasonable Maximum Exposure Scenario.
Population
Resident Worker" Worker' Visitor" Visitor4'
McdiunilExposure Current Future Current Future Current Future Current Future Current Future
PathwaY. (ofT-site) (ofT-site) ( on-site) (on-site) (on-s ite) , (on-site) (on-site) (on-lite) (on-lite) (on-lite) (on-lite)
AIR
Volatile Inhalation Yea Yea Yea Yes Yes Yea Yea Yea Yea Yea Yea
SOIL
Particulate Inhalation No Yea Yea No Yes Yea Yea No No No No
Ingestion No Yea Yea No Yes Yea Yea No No No No
GROUNDWATeR
Volatile'lnhalation , Yel Yea' Yea No No No No No No No No
Ingestion Yel Yea Yea No Yea No No No No No No
SURFACE WATeR
Volatile Inhalation Yea Yea Yea Yea Yea No No No No No No
Ingestion' Yel Yea Yes No No No No No No No No
SEDIMENT
Inges~on ,YeI Yea Yes Yea Yea No No No No No No
II Chronic long-tenn expolures were evaluated for thil population.
V Subchronic expo lUres were evaluated for thil population.
3/ Visitor represents golferi (adults).
41 Visitor represents loc:cer playing children.
\ :
, ,
~
~
00
-------
McChord AFB Area DI ALGT ROD
Page
49
2.
Exposure Assessment
a. Exposed Populations: For this assessment, exposure pathways were evaluated
for five receptors: residents, long-term workers, short-term workers, adult recreational
visitors, and child recreational visitors. The exposure pathways evaluated for each
population are presented in Table 9.
Potentially exposed populations include ALGT residents who continue to utilize their
drinking water wells or chose to install new wells. Although most of these residents have
been transferred to the Lakewood Water District water supply system, their wells have
generally not been abandoned. If the contamination were to migrate laterally or to deeper
aquifers, additional residents of ALGT or McChord AFB would be similarly exposed if
. .
water supply wells screened in the shallow or deeper aquifers became ccmtaminated.
b. Exposure Point Concentrations: Exposure point concentrations, including
averages and maxima, were derived for each medium of exposure "(soils, groundwater,
surface water, and sediments) for as many contaminants as w~re detected in each (See .-.
Tables 10 through 12). Generally, a reasonable maximum exposure concentration (RME,
based on a 95 percent upper confidence limit on the arithmetic mean contaminant
C9ricentration) could not be accurately computed because. ~th the limited number of. data
the RME was often found to be greater than the maximum value. In these cases, the
RME concentration was set ~ual to the highest (or in some cases, the only) measUred
value.
-
.,
- The aI)alytical results for soil were averaged for all the samples. in a boring. The hig.hest
average concentration, for all the borings in the source area, was then selected as tht:
exposure point Concentration for that source area. As there were a limited number of
samples analyzed in each area, the RME ahd average values could not be accurately
calculated. For these compounds, only the single analytical result was used.
For groundwat~r, individual wells were chosen to be representative for each source area,"
generally on the basis of proximity to the site and having the highest concentrations' .~
among the wells in the vicinity. For volatile organic compounds, the concentrations for
each sampling round were used to derive a maximum as well as an average value. For
other contaminants (semivolatiles, metals, and pestici<;les), where only one sampling
-------
Table 10. Soil Exposure Concentrations Used in the McChord Area D Risk Assessment.
Site 4" Site 5 and 39v Site 6" Siter'
B.M,g RMI! BMg ftMg
Inoreanics (ul!!ke):
Aluminum 2.351!+07 1.411!+07 8.091!+06 1.51E+07
Anenic 8.60E+03 3.40E+03 5.80E+03 6.001!+03
Barium 1.281!+05 5.301!+04 <5.501!+04 7.301!+04
Cidium < 1.40E+03 4.701!+03 < I.40E+03 1.20E+03
Calcium \.99E+06 3.421!+06 3.59E+06 3.22E+06
Chromium I.60E+04 2.00E+04 1.80E+04 2.IOE+04
Cobalt < t.40E+04 < 1.10E+04 < 1.40E+03 <1.IOE+04
Copper 2.30E+04 3.101!+04 I.40E+04 3.00E+04
Iron 1.508+07 1.958+07 8.27E+06 1.978+07
'Lead 2.40E+04 5.901!+03 8.60E +04 7.908+03
Magnesium 3.40E+06 5.52E+06 2.238+06 4.66E+06
Manganese 5.84E+05 3.031!+05 2.021!+05 2.77I!+05
Mercury 1.908+03 < 1.108+02 1.208+03 1.608+03
Nickel 2.80E+02 3.001!+04 1.608+04 3.201!+04
Potassium < 1.368 +06 < 1.078 +06 < 1.388+06 < 1.128+06
Sodium < 1.36E+06 <1.071!+06 < 1.381!+06 < 1.128+06
Thallium <2.708+03 <2.IOE+03 <2.808+03 <2.208+03
Vanadium 3.908+04 3.508+04 2.308+04 4.108+04 l
Zinc 5.408+04 3.701!+04 6.40E+04 4.IOE+04 CD
Oreanics (ul!!ke): .
Halogenated Aliphatic.:
Tetrachloroethylene (PCE) . 0.14" 0.08 0.05 48
1,1 !2.2- Tetrachloroethane 0.14 114 <0.031 4.7 VI
o
-------
Table ~O. . Soil Exposure Concentration~ Used iri the McChord Area D Risk Assessment.
.' Site 4" Site 5 and 39v Site 6" Site .,.,
RMB RMB RMH RMB
Trichloroethylene (TCE) 0.31 138 0.91 311
I, I , I-Trichloroethane (TCA) .0.55 0.24 2 0.44
1,1,2- Trichloroethane (TCA) <0.03 <0.02 <0.021 <0.03
1,l-DiQhloroethane (DCA) <0.10 <0.07 <0.073 0.3
1,2-Dichloroethane (DCA) <0.04 <0.03 0.04 2.5
I,I-Dich~oroethylene (DCE) 1 <0.18 0.9 II 5.2
cis-I ,2, Dichloroethylcne . i <0.13
.f\i . 34 <0.12 27
(cDCE) , '.' .
trans.I,2,.D~E (tDCH) <0.14 10 <0.10 1.1
Vinyl chl~~e (chlorocthylene). <:0.25 <0.19 <0.19 <0.24
Chloroin~hane (methyl chloride). <0.11 <0.09 <0.083 <0.11
MethylClie Chloride 18 148 320 53
(dichloromcthane)
Chlororonn (trichloromethane) . <0.07 <0.05 <0:052 0.09
DibromoehlOromethanc <0.12 <0.10 < 0.094 0.11
Bromodichioromethanc <0.14 <0.11 <0.10 0.09
.'
TrichlordOuoromctJiane <6 6 <31 9
1,2-Dichlo.ropropanc <0.06 <0.04 <0.042 0.63
I ,2,3-Trichloropropanc NA <0.1 NA 3.6
Heuchlorobutadicne 39.8 <0.1 <957 <0.1
..
Aromatic Compounds: 1
Bcn7.c:ne 0.97 2.4 1.9 13
~
Ethylbcnz.enc. <0.28 100 0.34 1,268
Toluene 4.6 9 1.2 4,190
Xylcoes (total) <6 210 <6 6,230
'\: VI.
-------
Table 10. Soil Exposure Con~ntrations Used in the McChord Area D Risk Assessment.
.
: Site 4" Site 5 and 3921 Site 6" Site 74/
.' .;
,Bhm B.t!:re BMIi JWg
ChlorobCnzene <0.28 298 <0.21 1.2
1 ,2-Dichlorobcnzene ' <0.56 ,. 0.1 <0.42 10
1 ,3-DIc~lorobenzene <0.56 0.1 <0.42 0.5
1 ,4:-Dicblorobenzene' , ,<0.42 0.15 <0.31 600
1,2,3- Trichlorobenzene N/A <0.1 N/A <0.1
1,2,4- Trichlorobcnzene <398 <0.1 <957 <0.1
1 ,3,5-Trirndhylbcnzene N/A 6.5 N/A I 131
1,2,4- Trirndhylbcnzene N/A 13.4 N/A 213
Styteno ' <6 <0.1 <6 7
lIopropyJbenzene N/A 0.3 N/A 4.7
n-propylbenzene '.'. N/A N/A 7.7
Icc-BuiyJbenzene N/A 0.6 N/A 4.4
tert-B~ylbenzene N/A 1.2 N/A <0.1
n-ButY,I~e N/A <0.1 N/A 485
p-isopropyltolucne N/A .. 1.3 N/A 366
Q1bm'
'.
~. ..
Ca,rbo,,' dilulfide <6 <5 <31 <5
Acetone' 630 605 755 800
2-Butanone (Mdhyldhylkdone, 130 <11 N/A 165
MBK) Z
4-Mdhyl-2-pcnthanone (MIBK) <11 1,750 <12 365
n
2-HeJUinonc (butybnthylkdone) <11 985 <12 30
Naphthalene <398 67 <957 135
,
2-Mc:tJiylnapthalcne <398 815 <957 <364
'I\cenilpbthene <398 91 <957 <364 VI
1'0,)
-------
Table lO~ Soil Exposure Concentrations Used in the McChord Area D Risk Assessment.
Site 4" Jr Site 5 and 39v Site 6" Site 74/
.RMB RMB BMg BM.g
Fluorene <398 115 <957 <364
Phenanthre~e <398 305 <957 <364
2~hloroc:thyl-vinyl-dher <0.1'8 <0.14 <0.14 0.13
Di-n-butylphtha1ate ~398 805 <957. <364
bi8-(2-dhy~exyl)phthalate <398 430 220 88
Di-n-oc:tylphthalate <398 200 <957 I <364
, 4-Mcthylphenol 150 <370 <957 <364
Benzoic: Acid 480 < I ,848 <4,783 < 1,822
Beta BHC <11 19 12 9.2
Delta BHC' <11 <8.3 16 <8.3
ChlorodAne <110 <83 460 <83
Dieldrin' " <22 49 <22 <17
4,4' DDT ~ ' <22 37 <22 <17
4,4' DDD <22 42 32 <17
4,4' DD~ <22. 79 <22 <17
II
21
31
41
N/A
Con~tration. at Site 4 were derived U8ing the '~ults from 80ririg DB-24.
Concentration. at Site 5 and 39 were derived U8ing the results (rom BOring8 DB-S, DB-19, DB-27, DB-28, and DB-29.
Concentrationl at Site 6 were derived uiing the 'results (rom BOring8 DB-3, DB-17, and DB-18.
Coi1C:entration. at Site 7 were derived uling the results (rom Boring. DB-2, DB-12, DB-IS, DB-16, DB-15, and DB-26.
Denotca not applicable . . ,
1
~
\.II
~
'.: .
.
-------
Table 11. Groundwater Exposure Concen~tions used in the M~Chord Area D Risk Assessment.
: S~te 4 .' Site 5 and 39 Site 6 Site 7 Offsite (W-lc)
.~ . BM8 BM.g BM,g 8MB
A1u~ii1um <200 362 264 4,270 200
Ancnic <:10 <10 <10 14 <10
'.
Barium <200 <200 <200 <200 <200
Cadmium.
-------
Tabl«( U. Groundwater': Exposure Concentrations used in the McOhord Area D Risk Assessment. .
Site 4. . Site 5 and 39 Site 6 Site 7 Off site (W-lc)
Or2anics: l!YSJ. . . BM.,g .8i!1 BM.g AVO ~ &si. BM,g AYJi BM,g
Tetrachloroethylene (PCE) 0.315 0.52 <0.03 <0.03 <0.03 <0.03 <0.055 0.06 0.03 <0.03
1,1,2,2-T~rachlorocthane <0.03 <0.03 . <0.03 '<0.03 <0.03 . <0.03 <0.03 <0.03 <0.03 <0.03
Trichloroethylene (TCE) 0.063 0.07 .72.2 82 0.066 0.08 2.261 5.5 7.2 10.5
1, I , I-Tric:hloroethane (TCA) 0.24 0.39 . 6.866 18 0.087 0.16 0.02 0.025 0.07 0.07
I, I ,2- Trichloroethane (TCA) <0.02 <0.02 0.055 0.105 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02
1, I-DichlorOcthane (DCA) <0.07 <0.07 '3.429 5.3 <0.07 <0.07 0.445 0.45 0.16 0.16
I ,2-Dichloroethane (DCA) <0.03. '<0.03 0.20.1 0.54 <0.03 <0.03 0.026 0.038 0.074 0.074
1 ,I-Dichtoiocthylene (DCA) <0.13. : <0.13 0.225 0.56 <0.13 <0.13 <0.13 <0.13 0.13 0.13
cis-l ,2-Dichloroethylene (cDCE) <0.01' <0.01 208.1 320 <0.1 <0.1 3.058 8 11.6 12.8
trans-l;2,-DEC (tDCE) <0.1 '. <0.1 .. 0.131 0.19 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1
Vinyl chloride (chloroethylene). <0.18 <0.18 <0.18 <0.18 <0.18 <0.18 0.455 0.82 <0.18 <0.18
.'
Chloromethane (methyl chloride) <0.08' <0.08 <0.08 <0.08 <0.08 <0.08 0.655 1.05 <0.08 <0.08
Methrclene Chloride
(dich orom~8nc) 1.3 2.5 2.526 7 <0.2 <0.2 3.668 7 0.26 0.26
Chlorofonn(trichloromethane) <0.05 <0.05 0.043 0.054 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05
Dibromochloromethane <0.09 <0.09 <0.09 <0.09 <0.09 <0.09 <0.09 <0.09 <0.09 <0.09
Bromodicilloromcthanc <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1
TrichloroOuoromethane
-------
Table 11. Groundwater Exposure, Concentrations used in the McChord Area D Risk Assessment.
, Site 4 Site 5 and 39 Site 6 Site 7 Offsite (W-lc)
Aromatio Comoounds: AY.SJ. RM.e 'AVO RMB AVO BMg AYSJ. BM.e AY.SJ. RM.e
Benzene 0.09 ,0.09 ,<0.2 <.02 <0.2 <0.2 0.725 1.35 <0.2 <0.2
EthylbCnunc <0;2 <0.2 <0.2 <0.2 <0.2' <0.2 33.16 98.5 <0.2 <0.2
Toluene
-------
Table 11., Groundwater Exposure' Concentrations used in the McChord Area D Risk Assessment.
Site 4 Site 5 and 39 Site 6 Site 7 Offsite (W-lc)
. Q!hm:' Ava RMB bYJ1 RM,g Ava RMB Ava ~ AY.Si. BM,g
Carbon disulfide <5 <5 11.33 11.33 <5 <5 <5 <5 <5 <5
Acetone <10 <10 <10 <10 <10 ,<10 <57.5 <110 <10 <10
2-Butanone (Mcthylcthylketone, <10 <10 <10 <10 <10 <10 <10 <10 <10 <10
MEK).
4-Methyl-2-,pcnthanone (MIDK) <10 <10 <10 <10 <10 <10 <10 <10 <10 <10
2-Hexanonc-(butylmcthy1lcetone). <10 <10 <10 <10 <10 <10 <10 <10 <10 <10
Naphthalene, . <10 <10 <10 . <10 <10 <10 <10 <10 <10 <10
2-Mcthylnapthalcne <10 <10 <10 <10 <10 <10 <10 <10 <10 <10
Accnapthene <10'. <10 <10 <10 <10 <10 <10 <10 <10 <10
Flourene .' <10 <10 <10' <10 <10 <10 <10 <10 <10 <10
Phenanthrene <10. <10 <10 <10 <10 <10 <10 <10 <10 <10
2-chloroethyl-vinyl-dhe~ <0.13 <0.13 <0.13' <0.13 <0.13 <0.13 <0.13' 0.13 <0.13 <0.1
3
Di-n-butylp~thalate <10. <10 <10 <10 <10 <10 <10 <10 <10 <10
bis (2.:ethylhexyl) phthalate <10' <10 <10 <10 <10 <10 <10 <10 <10 <10
Di-n-Oetylphthalate <10 <10 <10 <10 <10 <10 <10 , <10 <10 <10
4-McthylplJenol <10. <10 <10 <10 <10 <10 <10 ,<10 <10 <10
Benzoic acid <50 '<50 <50 . <50 <50 <50 <50 <50
-------
, ,
'. " . .
, , '
Table 11. Groundwater Expo~ure COl)centrations used in the McChord Area D Risk Assessment"
, Site 4 ' , Site 5 and 39 Site 6 Site 7 Offsite (W-lc)
Pesticides:
Beta BHC <0.01 <0.01 ',<0.05 <0.05 <0.01 <0.01 <0.05 <0.05 <0.05 <0.05
Delta BHC <0.01 '<0.01 '<0.05 <0.01 <0.01 :C::O.Ol <0.05 <0.05 <0.05 <0.05
Chlorodane <0.1 <0.1 <0.5 <0.5 <0.1 <0.1 <0.5 <0.5 <0.5 <0.5
Dieldrin <:0:02, <0.02. <0.1 <:0.1 <0.02 <0.02 <0.1 <0.1 <0.1 <0.1
4,4" DDT <0.02 <0.02, <0.1 <0.1 <0.02 <0.02 <0.1 <0.1 <0.1 <0.1
4,4' DDD <0,02 <0.02 <0.1 <0.1 <0.02 <0.02 <0.1 <0.1 <0.1 <0.1
,. <0.1
4,4" DDE <0.02 <0.02 <0.1 <0.02 <0.02 <0.1 <0.1 <0.1 <0.1
. '
i
n
v.
00
'\ :
-------
. ....
Table 12.. Surface Water and Sedi.!1Jent Exposure Conce~trations used in the McChord Area D Risk Assessment.
~merson Lake Whitman Lake
.: Surface Water Sediment Surface Water Sediment
. .'
-------
McChord AFB Area DI ALGT ROD
Page
For current off-site residential exposures to groundwater, Well W-lc was used to .
represent the maximum concentrations which occur beyond the base boundary. Since the
only analyses for samples from EPA Well W-lc were for volatiles, concentrations of
other contaminants were taken from the results in Well DZ-07, which was considered the
cloSest and most representative well analyzed for these contaminants.
For future off-site residential exposures, the highest concentrations found on-site were
assumed (under worst case conditions) to be advected off-site. The analytiCal results in
. Well DA-07a were also used for this exposure scenario.
Two surface water bodies were chosen as worst case exposure points: Emerson Lake for
off-site residents and Whitman Lake for on-site. The only data available for surface
water and sediments was for TCE and the 1,2-DCE isomer. Both average and maximum
exposure concentrations were developed based on different sampling rounds.
Contaminants in soil, groundwater, or sediments and surface water may enter the
. atmosphere by'either volatilization or through disturbances which suspend particulate
matter. Air modeling was performed using the techniques outlined in the Superfund
Exposure Assessment Manual to ~stimat~ vapOr and. particulate inhalation expos~re
. co~~ntfcitions. These con~~~ti~ns,~e~'umm~~ i~.theH~~.ariH~ih Risk
Assessment, November 1990. ..' . . .' . .
. .
. .
. .
. . t .
. ,c. Chemi~ Intake by' Exposure PatQway: . Cheri1i~ intak~S (mg/kg-day) were' .
estimated for each exposure pathway using the exposur~ point concentrations and 'other
exposure p&ameters, sucn as soH and water ingestion rates, body weights, and exposure
. . frequencies and durations;Pathway:'specificequations from the RAOS guidanCe were .
used to estimate chemical intakes. . . .'
3.
Toxicity Assessment
For"wci~ogenic' chemicals', siopefattors:a.re estimated' using' aoonservative mathematical
model which estimates the relationship between experimental exposures (Le., doses) and .
the development of cancer (Le., r~sponse) that is derived from human or animal studies;
Since there is much. uncertainty in the dose-response values generated using this
procedure, the upper 95 percent confidence limit of the slope of the dose-response curve
is normally used in deriving the slope factor.
.
60
" .
.'
-------
McChord AFB Area DI ALGT ROD
Page
61
For non-carcinogenic chemicals; reference doses (RIDs) are used as benchmarks for toxic
endpoints of concern. The goal in developing an RID is to identify the highest
no-observed-adverse-effect-Ievel (NOAEL) or the lowest-observed-adverse-effect-Ievel
(LOAEL) from well designed human or animal studies. One or more order-of magnitude
uncertainty factors are incorporated to adjust this level based on the following
considerations: (i) the duration of the experimental exposure, (2) effects elicited (if any),
(3) extrapolation of the data to other species (Le., interspecies variability, such as
extrapolation to humans), and (4) sensitive subgroups (Le., intraspecies variability).
Additional modifying factors varying between a value of 1 and 10 may also be
incorporated in the derivation of the RID if additional considerations are necessary.
RIDs and slope factors for the Area D risk assessment were taken from EPA's
computerized Integrated Risk Information System (IRIS); Health Effects Assessment
Summary Tables (HEAST); Drinking Water Health Advisories; or personal
communication with EPA Region 10 Risk Assessment staff.
4.
Risk Characterization
. a. . Cancer RIsk:" Carcinoge~c risk is estimated 'as the iricrementaI pro~ability of' , ~
aJ.1 individual ,developing cancer above'the nonnal background poi>ul~tion inCidence oyer a '
lifetime as a result of exposure to a chemical either known or suspected to cause cancer.
To estimate cancer risk, slope factors are co~bined 'Yith site exposure information to
, es~mate the in~remental cancer risk, which represents a pr~bability of contracting 'cancer ~
~d which is usually expressed in scientific notation' (e.g., 1 x 10-4 or 1-(4). An excess '
lifetime cancer risk of 1 x 10-4 ~dicates that, as a pla~s!ble u~perbound" an individual ,
has a on'e'in 'ten thousand chance of developing canCer'in a lifetime'as a result of '
site-related exposure to a carcinogen.
For known or suspected carcinogens, acceptable exposure levels are generally
.. CC?ncentration, levels ,tftat,represent ~ ,ex~ss upperbound, JiJetim,e, ~cer ri~k .to, an', " ,
, individual of between' l'x iC>-4 and 1 x,10-6 using information on 'the relationship
between doSe and response (NCP 1990).
,~
b. Non-cancer Risk: For non-carcinogens, the measure used to describe the ,
potential for toxicity in an individual is not expressed as a probability. The potential for
non-carcinogenic effects is evaluated by comparing an exposure level over a specified
-------
McChord AFB Area D/ALGT ROD
Page
62
ratio of exposure to toxicity is called a Hazard Quotient. The Hazard Index (HI) is the
sum of more than one hazard quotient for multiple substances andlor multiple exposure
- pathways. Potential non-carcinogenic effects may be of concern if the m exceeds unity
(i.e., m > 1).
c.
Human Health Risk Characterization Summary
A quantitative summary of the maximum risks for cancer risks and hazard indices
identified for contaminants of concern over all receptors, sites and land use scenarios is
presented. in Tables 13A and 13B, respectively. Critical receptors and associated sites are
also presented.
. .. .
Table 14 summarize the maximum estimated risk for both carcinogenic and
noncarcinogenic effects. The cumulative risk includes groundwater ingestion and volatile
inhalation, and assumes exposure to the highest level of contamination for each
contaminant found within the shallow unconfmed ~quifer. This cumulative risk
: recognizes .that- the .coJ.1taIT1ination is likely to migrate. within .th~ plum~ and assumes that, .
for a future use scenario, a single drinking water production well could,graw . . .
. .. cq~tamina~on from. a large porti.on of the contaminant plume. The highest risks in the
.. : ..n risk assessiI1ent tended to be aSsOciated. with .the futpre on-si~ .residential .sceilario.. .. .
. Although this. i~d use scenario. is not ,considered likely' giv~ .thaftbe existing .useof
~ D will. probably. not change, remediation of the groundwater fs ~equired u.nQer the .
NCP to restore benefiei~ ~Ses of the ~rinking'water aquif~.. Actual or' ~~ed .
releases of hazardous $ubsumces. from this site~.~ ~~t addr~~ .by imp~em~nting the
response action selected in this ROD, may present an imminent" and .substantial
. endang~rrnent to public healtll' we1far~, or the em-ironment. .
5.
Uncertainty
, -'.
Major components of the assessment which decreased the certainty of the results were (1)
. .the toxicity reference val~es used, and the lacJ.c of values for seyeral chemicals; (2)
.limitation~ i~ ~ntanrinant ~ncentrcition da~. fo~ ~ils~ .gro~nd~ter~'~d>~d~ .wateii
(3) the inclusion of concentrations at a level of one-half the detection limit for many
chemicals; and (4) the use of a number of assumptions to establish exposure parameters
in computing chemical intakes.
.
. .
,.
-------
Page
63
Table 13A. Maximum Estimated Cancer Risk for Contaminants of Concern
under the Reasonable Exposure Scenario. v
Target Maximum Estimated
Chemical Site PopulBtion Cancer Risk
Arsenic 7 Resident, Onaite, Future 8.0E-0421
Benzene 7 Resident, Onsire, Future 6.2E.06
Beta SHC 7 Resident, Onsite, Future l.SE-06
Bis 4, S139, 6, 7 Resident, Onsire, Future 2.2E.06
(2-cthyhexyl)phthalate
Offsire Reswent,Off8ite,Future,C~t 2.2E.06
Chlordane S139,7 Resident, Onsite, Future 1.0E-oS
Off sire Resident, Orfsite, Future, C~t. 1.0E-oS
Chromium 7 Resident, Onsitc, Future 7.0E.06
l,l-DichloroCthane Offsitc Resident, Off site, Future l.SE-oS
S139 Resident, Onsite, Future 1.SE-oS
l,2-Dichloroethane Off site Resident, Offsite, Future 7.8E.06
S/39 Resident, Onsite, Future 7.8E-06
"
1,1-Dichloroethylene . Offsite Resident, Off site, Future 2.4E~S
S/39 Resident, Onsite, Future 2.4E-oS
4,4'-DDT S139, 7 Resid~t, ~site, F.uture 2.7E.()6
. .: Offsite . Resid~t, Off site, Future; Current 2.7E.06
'. Dieldrin SI39. ...'. Resident,. On'site, Future 2.7E-oS
Methylene Chloride. S139, 7 Resident, Onsite, Future 1.4E-oS
OO:site Resident, Offsite, Future 1.4E-oS
Styrene ".'4,6,7. Resident, Onsite, 'Future 3.0E.06
. .
Offsite . .
Resident, Offsite, C~t 3.0E.06
TrichlorOethylene S139 Resident, Onsitc. Future 9.1E-oS
.Offaire . Resident, Off site, FUture 9.1E-oS
:0--:"' .
Vinyl Chloride 7 Resident. Off site. Future 7.SE-oS
. .
," . .
. .". .
-------
.
Table 13B. Maximum Estimated Hazard Indices for Contaminants of Concern under the Reasonable EXpOsure Scenario. II
Chemica1
Page
~
StyrcIIe
Site Tar2et Population Maximum Estimated Hazard Index
7 Resident, Onsite, Future 4.5E~1
4, S/39, 6, 7 Resident, Onsite, Future 7 .9E~3
S/39, 7 Resident, Onsi1e, Future 1.3E~1
Offsite Resident, Offsite, Future, Cunent 1.3E~1
7 Resident, Onsite, Future 2.1E~1
S139,7 Resident, Onsite, Future 3.2E-03
S/39 Resident, Onaite, Future 8.3E-03
Offsite Resident, Offaite, Future 8.3E-03
S/39 ... Resident, Onsite, Future 1.0E+OO
Offsite Resident, Offsi1e, Future 1.0E+OO
5/39 Resident, Onsite, Future 2.0E-03
Off site Resident, Offsite, Future 2.0E-03
S/39 Resident, Onsite, Future 3.3E~
4 Short Term Worker, Onsite, Future, Current 1.6E+OO
S/39,7 Resident, Onsite, Future 4.7E-03
Offsite Resident, Off site, Future 4.7E~3
4,6,7 Resident, Onsite, Future 3.9E~
Offsite Resident, Offsite, Current 3.9E~
4, S/39. 6, 7 Resident, Onsite. Future 2.3E+OO
Arsenic
Bis(2-ethyhexyl)phthalate
Chlordane
Chromium
4,4'-DDT
1,l-Dichlorodhane
Cis-! ,2-Dichlorocthy1cne
1,I-Dichloroethy1eue
Dieldrin
Manganese
Methy1eue Chloride
Thallium
11 Critica1 Exposure PathwayslReceptors/Sites for Contaminants of Concern Evaluated for Area D
Con~tofConcern EPA Current Use Future Use
Carcinogen
Classification Off Post On Post Off Post On Post
O~GANlCS: A ging,ginhlzaf7
Benzene
dieldrin b2 ging/res pglres gjn~/4,S&39,6,~, aing/m/S&39,
, gin tw/4~&39,6. ,
, .
1,l-dil:hlorocthylene c 'ging,ginhlres ging,ginhlres ging/ginhlrcsl4,S&39 ,6,7, ginglltwlS&39
, . .cis-l,2-diochloroethylene ' ging/res ging/res/S&39
, metJir1cne chloride . b2, . ".0 gini,ginhires ginhlres/4, :ginh,ging/resiS&39,1 '
,:tPchloroethy1ei1e "b2 ging,iinhlrcs ' 'gmg,ginhI~ ,'ginh,~gI~S&39.7, gingl1tw/S&39
vinyl Chloride a ging,ginhlres gmg,ginh!res, ~~!tS'~~,~6",. '
~ b2 pg/res, &i!agires/4;6,7
,l,l-Dic!U0roethane ,b2. .gi!ig/Rs' gin~/rei,hw/~9, gingi~n
l,2-Dichloroethane b2 . ,". "ging,giiihlres gmg,g1nJi!iea/S&39
4,4-DDT b2 ginhlra ginhlra ginhlrcal5&39. 7
BETABHC e ging/res gir:g/resn
Chlordane b2 ging/res ging/res ginglhwlS&39, 7, ging/res/4,S&.39 ,6,7
Bis(2-ethylbexy1)phthalate b2 ging/ra ging/res ging/res/4,s&39,6,7
INORGANIC: a ging/res ging/res ~f/sin~res JI/i\-6,7,
Arsenic ,sm res} &3 ,amgl1twlS&39
Chromium(Vl) a apinhlrca/4, apinhlrca,hw/S&39,6,7
Man~ese apinh/stw/4 apinhlatw/4
TbaniiuD ' " ging/res' " ' ging/rea' , ' ,ging/res,hw/4,5&39,6,7
,,'
, ' ,
ging gro.undwater ingestion spinh soil particulate inhalation
res ~Ident S fiB'Trd~~l Vapor Inhalation ...
stw a ort-tcrm worker ng~erm !{}.oorker
4 alte 4
-------
Table 14. Risk : from Exposure to RME Concentrations in Groundwater (Baseline). Off-Post Residents (Current).
Noncanccr " ,
Cancer' . . Noncancer Cancer
RM8
'.
Contaminant Oral RID Inh RID Oral CPF Inh. CPF Concentration Ora! dosc Inh. dosc. Oflll Inhalation Oral Inhalation
..
(mg/kg-d) (mg/kg-d) I~(mg/kg-d) I/(mg/kg-d) (mglL) . (mg/kg/d) (mg/kgld) HI HI Risk Risk
Arscnic 1.008-03 N/A 1.758+00 1.508+01 5.008-03 1.578-04 N/A 1.578-01 N/A 38-04 N/A
Barium . 7.008-02 1.008-04 N/A N/A 1.008-01 3.148-03 N/A 4.498-02 N/A N/A N/A
-
Cadmium 5.008-04 N/A .' N/A 6.108+00 2.508-03 1.86E-05 N/A 1.518-01 N/A N/A N/A
Chromium . . 5.0!)8-O3 N/A N/A 4.IOE+01 5.00E-03 \.518-04 N/A 3.148-02 N/A N/A N/A
Lead N/A N/A N/A N/A 2.50E-03 7.86E-05 N/A N/A 'N/A N/A N/A
Manganese 2.008-01 3.008-04 N/A N/A 7.50E-03 2.368-04 N/A 1.188-03 N/A N/A N/A
Thallium 7.00~-O5 N/A N/A JollA 5.00E-03 1.518-04 N/A 2.248+00 N/A N/A N/A
Bcnzene N/A N/A 2.908-02 2.908~2 1.008-4 3.148-06 1.268-05 N/A N/A 98-08 48-07
Bromodichloromctbanc 2;008~ N/A 1.30 8-01 N/A 5.00£-05 1.518-06 6.298-06 7.868-05 N/A 28-07 N/A
Chloroform 1.008-02 2.308-03 6.IOE-03 8.108-02 2.50E-05 1.86E-01 3.148-06 7.868-05 1.37B-03 5E-09 38-07
Chloromethane N/A N/A 1.308-02 6.308-03 4.00E-05 \.268-06 5.038-06 N/A N/A 28-08 38-08
1,4-Dichlorobcnzcnc N/A 2.008-01 ' 2.40£-02 N/A 1.S0E-04 4.718-06 1.898-05 N/A 9.438-05 18-07 N/A
1,2-Dichlorocthane ' . N/A N/A 9.10£-02 N/A N/A
9.108-02 7.40£-05 2.338-06 9.308-06 IE-O? 88-07
1,l-Dichlorocthylene 9.008-03 .N/A 6.00£-01 1.80B-01 6.50£-05 2.048-05 8.178-06 2.27B-04 N/A 1 B-06 18-06
cis-I,2-Dichlorocthylcne' I.OQ8-02 N/A N/A N/A 1.28E-02 4.02B-04 I.6IE-03 4.02B-02 N/A N/A N/A
Tetrachloroethylene 1.00B-02 N/A 5;108-02 3.308-03 1.50£-05 4.718-07 1.89B-06 4.71B-05 N/A 2B-08 68-09
1, 1 ,2~Trichloroethane ',' 4.00~-03 N/A 5.70B-02 5.70B-02 1.00£-05 3.14B-07 1.26B-06 7.86B-05 N/A 2B-08 7B-08
'\ .:.
1
n
-------
.. .
Table 14. Risld"rom Exposure.to"RME Concentratio~s in Groundwater (~seline)" Off-Post Residents (Current).
Noncancer
Cancer
Noncancer
Cancer
RME
Contaminant Oral RID Inh RID oia.. CP~ .: Inh. CPF Concentration Oral dose Inh. dose* Oral Inhalation Oral Inhalation
(mglkg-d) . (mglkg-d). . ' lI(m~lkg-d) I/(mglkg-d) , (mglL) (mglkg/d) (mglkgld) HI HI Risk Risk
Trichloroethylene N/A N/A 1.10E-02 . 5.95E-03 . 1.05E-02 3.30E-04 1.32E-03 N/A N/A 4E-06 8E-06
Vinyl Chloride " N/A . N/A 2~30E-00 1.48E-ol 9.00E-05 2.83E-06 1.13E-05 N/A N/A 7E-06 2E-06
Total NoOC8UCft' Hazard Index = .
Total NoDC8UCft' Ha.ant lodex (w/o area J*kground~*)=
Total Caucer Risk = ',1:
Total Cancer Risk (",/0 area bacqrouad..) ...
, 2,,68
.0,,04
'. 3E-04
. '2£.05
2.68E-OO
1 E-05
lE-05
TOTAL:
TOTAL (W/O AREA
BACKGROUND **):
Dose Pactor (Llkg)
91.25
53.46
40.73
33.46
23.62
23.34
594.43
860.2863821
0.031425987
1.46E-03
3E-04
4.07E-02
1.46E-03
lE-05
Lifetime Dose Pactor .
Calculations Age (yrs~)
0-1
2-5
6-8
9-12
13.15
16-18
19-75
ED (days)
1095
1095
1095
1095
1095
1095
20805
'\ : .
. .
EP (did) BW (kg)
1 11
1 17
1 25
.1 ..36
1 '. sf'
1 .. 61
1 .7Q
. .
AT = 27375
: Lifetime cummulative
. dose factor (Uk$fd): .
"
IR . (Lei)
1.00
0.83.
0,,93
'. . '1.10'
.1.10
.qo
.2.00
. .
Equations:
Oral Lifetime Avg. Dose = Cw((IR*EP*ED)/BW]/AT
Where: Cw... contaminanta concentration in water (mgIL)
IR ... Age-specific water intake rate (LId)
EP = Exposure frequency (did)
ED = Exposure duration (Total: 75 ycars)
BW = Age-specific body weight (kg)
AT = Averaging time (27375 d)
* Inh" lifetime average dose... 4 oral dose.
** Metal. detected were determined to be consistent with
concentration of metals in the area of background
samples" .
1
CD
8:
-------
Table 14. Risk from Exposure to'RME Concentrations in Groundwater (Baseline). On-Post Residents (Future).
Noncaneer Caneer Noncaneer Cancer
.. RMB
Contaminant Oral RID Inh. JtID Oral CPP . 'Inh. CPP Concentration Oral dosc Inh. dosc. Oral Inhalation Oral Inhalation
(mglkgo(!) (mglkgo(!) . lI(mglkgo(!) I/(mglkgo(!) (mg/L) (mglkgld) (mglkgld) HI HI Risk Risk
Ancnic 1. OOB-03 N/A 1.7S8+00 t.SOB+OI I.40B-02 4.4OB-04 N/A 4.4OB.ol N/A 88-04 N/A
Barium 7.00B-02 1.00B-04 .N/A . N/A I.00B.ol 3.14B-03 N/A 4.49B-02 N/A N/A N/A
Cadmium. .' S.OOB-04 N/A N/A 6.IOB+00 6.00B-03 1.89E-04 N/A 3.77B-ol N/A N/A N/A
Chromium S.OOB-03 N(A N/A 4.IOB+01 3.30B-02 1.04E-03 N/A 2.07E-ol N/A N/A N/A
Lead N/A N/A N/A N/A 7.80E-02 2.4SB-03 N/A N/A N/A N/A N/A
Manganesc 2.00B-ol 3.00E-04 N/A N/A 1.4SB+00 4.S6E-02 N/A 2.28B.ol N/A N/A N/A
Thallium " 7.00B-oS N/A N/A . N/A. S.OOB-03 I.S7B-04 N/A 2.24B+00 N/A N/A N/A
Benzenc N/A N/A 2.90B-02 2.90E~ 1.3SE-03 4.24E-oS 1. 70E-04 N/A N/A 1 B-06 SB-06
Bromodichloromethanc 2.00B-02 N/A 1.30 B-ol N/A S.OOE-oS I.S7E-06 6.29B-06 7.86B.oS N/A 2B-07 N/A
Chloroform . . I.00B-02 2.30B-03 6.10B-03 8.10E-02 S.40E-oS 1.70B-06 6.79B-06 1. 70B-04 2.9SB-03 lB-08 SB.o7
Chloromethanc N/A N/A i .30E-02 6.30B-03 1.0SE-03 3.30E-oS 1.32B-04 N/A N/A 4B-07 8B-07
1,4-Dichlorobcnzcnc N/A 2.00B.o1 2.408-02 N/A 9.20B-04 2.89E-oS 1.16B-04 N/A s.78B-04 7B-07 N/A
1,2 Dichloroethanc N/A N/A 9.IOE-02 9.10B-02 s.40E-04 1. 70B-oS 6.79B.os N/A N/A 2E-06 6B-06
1, l-Dichloroethylenc 9.00E-03 N/A 6.00B-ol ' 1.lioB~I' S.60E-04 1. 76E-oS 7.04B.oS 1.96B-03 N/A m-os 1 BoOS
. .
cis-l 2- ..
Dichloroethylcnc I.00B-02 N/A' '.N/A . N/A. 3.20B.ol 1.01B-02 4.02B-02 1.018+00 N/A N/A N/A
Tetrachloroethylcnc: I.00B-02 N/A s.10B-02 3.30B-03 s.20B-04 1.63B-oS 6.S4B.oS 1.63B-03 N/A 88.07 28-07
1, 1 ,2-Trichloroetha~e 4.00B-03 N/A S.70E-02 S.70B-02 1.0SB-04 3.30B-06 1.32B-oS 8.2SB-04 N/A 28-07 88-07
1
n
01
-.J
-------
Table 14. Risk from Exposure to RME-Concentrations in Groundwater (Baseline). On-Post Residents (Future).
Noncaileer
Cancer
Noncancer
Cancer
Contaminant
RMB
Oral RID . Inh. RID . . Orai CPP Inh. CPP Concentration Oral dose Inh. dose.
(mglkg-il) (mg/lcg-il). 'lI(mglkg-il) 1/(mglkg-il) (mg/L) (mg/lcg/d) (mg/lcg/d)
N/A N/A 1.1 OB-02 5:95B-03 8.20B-02 2.~8B-03 1.03 B-02
N/A N/A 2.30B+00 ;' 1.48B-01 8.20B-04 . 2.58B-05 I.03B-04
Oral Inhalation Oral Inhalation
HI HI Risk Risk
N/A N/A 3B-05 6B-05
N/A N/A 6B-05 2B-05
4.55B+00 3.53B-03 9B-04 I B-04
1.01B+00 3.53B+03 I B-04 1 B-04
Trichloroethylene, . ;
Vinyl Chloride
Total Nooeaneer HlZard Index = .
Total Noncancer Hazard Index (w/o a~ backlround..)~
4.56
1.01
, TOTAL:
TOTAL (w/o area
background ..):
Total eaneer Risk =,
Total Cancer Risk (w/o ami background..)=
'I~J
.2E-04
Lifetime Dose Pactor Calculations:
Equations:
Oral Lifetime Avg. DOle = CW((IR.Bp.BD)IBW]fAT
IR = Age-specific water intake rate (Ud)
BP = Bxposure frequency (did)
BD = Bxposure dul'!ttion (Total: 75 years)
BW = Age-specific body weight (kg)
AT = Averaging time (27375 d)
Age (yrs.) BD (days) EP (did) . . BW (kg) IR (Ld) Dose Pactor (L/lcg)
0-1 1095 1. . '12: LOO 91.25
2-5 1095 1 17 0.83 53.46
6-8 1095 . 1 15 0.93 40.73
9-12 1095 1 36 1;10 33.46
13-15 1095 1 .51 1..10 23.62
16-18 1095 1 ~1. -1.30 23.34
19-75 20805 1- 70' 2.00 594.43
..' .
860.2863821
AT =
27375
Lifetime cummulative dose factor 0.031415987
(Ultgld):
.
Inh. lifetime average dOle = 4 oral dOle
, Metals detected were determined to be consistent with
concentrations of metals in the area background samples.
..
1
n
, ;
0\
00
-------
Table 14. Risk from Exposure to RME Concentrations in Groundwater (Baseline). On-Post Workers (current).
, Noncancer Cancer Noncancer Cancer Noncancer Cancer
Oral' Inh. RID RME lfha1. Inha1.
, Oral CPP Inh. CPP Concentration Oral ose' Oral Dose' Oral Inhalation Oral Inhalation
Contaminant (ml!!ke-d) (me/k2-d) (ml!!ke-d) (me/ke-d) (me/U' Dose (me/ke/) Dose (melke/d) HI HI Risk Risk
Arsenic I.00B.:o3 N/A 1. 75E +00 ' 1.50E+Ol 1.4OE-02 2.4OE-04 N/A 1.28E-04 N/A 2.4OE-Ol N/A 2E-04 N/A
Barium 7.00E-02 I.00E-04 N/A N/A I.00E.() 1 1. 71 E'()3 N/A 9.14E-04 N/A 2.45E-02 N/A N/A N/A
Cadmium 5'.008-04 N/A N/A 6.108+01 6.00E'()3 1.03 E-04 N/A 5.49E-05 N/A 2.06E-Ol N/A N/A N/A
Chromium 5.00E-Q3 N/A N/A 4.19E+Ol 3.30E-02 5. 66E-04 ~/A 3.02E-04 N/A 1.13E'()1 N/A N/A N/A
Lead N/A N/A N/A N/A ,7.80E-02 1.34E-03 N/A 7.13E-04 N/A N/A N/A N/A N/A
Manganese 2.008-01 3.008-04 N/A N/A 1.45E+00 2.498-02 N/A 1.33E-02 N/A 1.248-01 N/A N/A N/A
Thallium 7.00E-05. N/A N/A . 'N/A 5.00i!'()3 8.57E'()5 N/A 4.578.()5 N/A 1.22E+00 N/A N/A N/A
Benzene N/A N/A 2.90B.()2 2.90B.()2 1.35B'()3 2.31B'()5 9.268-05 I.23B-05 4.94E-05 N/A N/A 48-07 1 E-06
Bromodichloromethane 2.ooE.()2 N/A 1.30E.() 1 " N/A 5.QOE.()S 8. 57E'()7 3.43E-06 4.57E.()7 1.83E-06 4.29E-05 N/A 6E-08 N/A
Chloroform 1.00E.()2 2.30E-03 6; 1 OB.()3 8.10E.()2 5.40E'()S 9.26E'()7 3.70E-06 4.94B.()7 1.978-06 9.268-05 1.618-03 38-09 2E-07
Chloromethane N/A N/A 1.30E-02' 6.30E-03 1.0S8.()3 1.80E.()5 7.20E-05 9.6OE-06 3.848-05 N/A N/A 1 E-07 2E-07
t ,4-Dichlorobenzene N/A'.. 2.00E-Ol 2.40E-02' N/A 9.20E-04 1.58E'()5 6.31E-05 8.41E-06 3.36E-05 N/A 3.158-04 2E'()7 N/A
1,2-Dichloroethane NIA N/A 9.10E.()2 9.10E.()2 5.4OE-04 9.26E-06 3.70E-05 4.94E-06' 1.97E-05 N/A N/A 4E-07 2E-06
1,l-Dichloroethylene 9.00E-03 N/A ' 6.00E-Ol 1.80E-Ol 5.6OE-04 9.6OE-06 3. 84E-05 5.12E-06 2.0SE-05 t.07E-03 N/A 3E-06 4E-06
cis-l,2-Dichloroethylene l.ooE.()2 N/A N/A ' N/A ' 3.20E'()1 5.49E-03 2.19E-02 2.93E'()3 1.17E-03 5.49E-Ol N/A N/A N/A
Tetrachloroethylene 1.00E-02 N/A 5.10E.()2 3.30E-03 ,5.20E-04 8.91E-06 3.57E-05 4.75E-06 1.90E-05, 8.918-04 N/A 2E-07 6E-08
1,1,2- Trichloroethane 4.ooE..q3 N/A 5.70E.()2 5.70E-02 1.05E-04 1.80E-06 7.20E-06 9.6OE-07 3.84E-06 4.50E-04 N/A 5E'()8 2E-07
Trichloroethylene N/A N/A UOE.()2 5.95E-03 8.20£-02 1.41E-03 5.62E-03 7.50E-04 3.00E-03 N/A N/A 8E-06 2E-OS
Vinyl chloride N/A N/A 2.30E+00 1.48E-Ol 8.20E-04 1.41E-05 5.62E'()5 7.50E-06 3.00E-05 N/A N/A 2E-OS 4E-06
Tobll Noocancer Hazard Index= 1.49 TOTAL: 2.488+00 1.938-03 3E-04 38-05
Tobll Noncancer Hazard Index' (""0 area b8ekground..)= 0.55 TOTAL ('1110 area background"): 5.51E-Ol 1.938-03 3 E.()S 3E-OS
Tobll Cancer Risk = 3E-04
Tobll Cancer Risk ('1110 area background..) = . 6E-GS
Equations: " Z
Oral Lifetime Avg. Dose = (CW*IR*EP*ED)/(BW*AT) ~
Where: CW = Contaminant concentation 'in water mg/L ,
JR = Daily water intake rate (2.0 Vd)
EF = Exposure frequency (219 dIyear)
ED = Exposure duration (40 yea~)
BW = Body weight (70 kg)
AT = Averaging time: (NC=14,600 days) $
(C=27,375)
, Inh. lifetime avg. dose ='\ 4' onil dose. .
-------
McChord AFB Area DI ALGT ROD
Page
70
Due to the uncertainty in these and other areas, conservative assumptions were made in
order to ensure protection of human health. Cancer and non-cancer risk estimates must
be carefully interpreted, particularly when evaluating non-carcinogenic effects where
uncertainty factors of 2 to 3 orders of magnitude are used in dose-response assessments.
B.
Environmental Risks
1.
Chemicals of Concern
Seven wetlands and ponds in Area D are fed by groundwater and surface water. The
Baseline Ecological Risk Assessment evaluated other chemicals which may be affecting
the aquatic and terrestrial biota of this area. Based on the results of the groundwater and
soil sampling effort, samples of pond surface water and sediments were analyzed for 23
organic chemicals and 13 metals using analytical techniques which provided the lowest
possible detection limits. In these samples, six pesticides (4,4'-DDT; 4,4'-2,2-bis(para-
chJorophenyl)-bi-dichloroethane [4,4 'DDD]); 4,4' -dichlorodiphenylethane [4,4-DDE]);
endrin ketone; dieldrin; and chlordane), three organic chemicals (fCE, cis-l,2-DCE, and
trans-l,2-DCE), and three metals (copper, lead, and zinc) were found above detection'
, limits. ' '
'. "
2.
, '
. . . .' . :
Exposure Assessment
The ECOlo~ical Risk Assess,ment consider~ the ris~. to animals and,.plants resulnng from "
": expOsure io the oontamlmited surface 'water'and sediment~ ' The assessment was' performed '
in several phases described below: '
'. . .
. '. . . . . '. .
a. ' Potential contaminant exposure routes from the (potential waste disposal area)'
source to biota that reside at the site were defined. '
, b~ Plants, terrestrial, animals, and aquatic organisms that may ,potentially, be
, "expoSed to CoJitaminants were identi~~: .. " ,
c. The risk assessment for the site was performed. Because of the number of '
chemicals of potential concern (81 in this assessment), the task was divided into two
parts: (1) an initial risk screen to identify the primary chemicals and metals of concern;
and (2) a quantitative risk assessment of the identified potentially harmful chemicals.
.
, ,
..
-------
.
McChord AFB Area DI ALGT ROD
Page
71
Based on Ute results of a survey, twelve species were considered to have potentially high
exposure intensity to contaminants in wetlands ~d ponds. These animals include
bullfrog, painted turtle, great blue heron, Canada goose, mallard, wood duck, ring-billed
. gull, river otter, muskrat, raccoon, beaver, and coyote. For this group, potential
exposure to contamination was considered high primarily because of their diverse feeding
habits, contact With wetland sediments, or duration of exposure in the wetlands and
ponds.
3.
Risk Characterization and Summary
Measured maximum concentrations of the chemicals found in the surface water and
mwmum calculated concentrations in interstitial water (as partitioned from the maximum
sediment con'centrations) were compared to those concentrations that are expected to
cause chronic (long-term, non-lethal) effects to biota. Only those chemicals expected to
cause chronic toxicity were evaluated in the full risk assessment. These chemiCals are
chlordane, 4,4'-DDT, 4.4'-DDD. 4.4'-DDE, dieldrin, endrin ketone, copper, lead, and
zinc.
- -
. .
. ..
The six. pestici~e.s and three metals listed above were. q~titatiyely. evaluated to a$sess .
the .risk f11'st for all aquatic (and terrestrial). biota, and ~en for species exPected .to exist.
in Area DI ALGT wetlands and ponds. Concentrations of interstitial water in ~iments
. . were estimated using conservative assumptions. Duck Pond, and Carter and ~tman
. Lakes, co~tafued 4:,4'.-D.DT in sediments, and, the!efore, interstitial.water ~ncentrations
that may pose chronic toxicity to invertebrates, although the concentrations in Carter and
Whitman Lakes impact less than 5 percent of the species.. Carter and Wh.itman Lakes
cO~tained zinc iD sediments and interstitial water concentrations which also ~Se chronic.
toxicity to invertebrates. Additionally, Whitman Lake surface water concentration of zinc .
may pose acute risk to approximately 17 percent of species. Baxter Lake surface water
may pose an acute and chronic risk to invertebrates due to copper and zinc. Estimated
. co~centrations of, chlordane ~ Duck Po.J.1d. interstitial. water prese~~ pot~ntial acute. toxici.ty.
. and potential chronic t6~icity .to nearly ~ inverteb~tes. . A sumtri~ of 'th~Se chemicals.
potentially causing a risk is listed below: ...
Surface Water
- Copper: Baxter Lake
-------
McChord AFB Area DI ALGT ROD
Page
72
..
Sediment
- Chlordane: Duck Pond
- DDT: Duck Pond, Carter Lake, and Whitman Lake
4.
Uncertainty
Sources of uncertainty in the ecological risk assessment include: (1) the analytical data for
chemicals in groundwater, surface water and sediments; (2) the toxicity data bases (i.e.,
.LC 50 and ACR values); (3) estimates of interstitial water concentrations from sediment
concentrations; (4) measurement of lake specific water quality parameters (e.g.,
.hardness); and (5) estimates of wildlife sediment ingestion. Because conservative
parameters were u$OO throughout the ecological risk assessment process, it is expected
that the risks are overstated.
VU. DESCRIPTION OF ALTERNATIVES
A.
Soil, Surface Water,. and Sediment
. .
. .. . .
. ~. (Ui the Human Health and Ecologic:3I Ba,selineRisk AS~S~Jilent; the levels of
contaIDinatioli" in the 'soil" surface water, and sediment will.not result in unacceptable
exposure t9 hazardous,substan~s. Therefore, it was de~rmined that no remedial action
, .
. '. is n~sary for ~i1, surface water, or sediment .to ensure protection of human health .and
, the enVironment, and no remedial alternatives were considet~ or developed. ' Ho..yever-,
groundwater contamination does exceed MCLs and four remedial attematives were
eVa1ua~ed 'in the feasibility study for the clean~up, of the groundwater. A description of
these aitematives'and the appliCable or relevant arid appropriate requireinents (ARARs)'
that apply are contained in the following section.. .
B.
Groundwater Alternatives
" ,
. ',' . ", . .. ".
. . '
The four remedial 8ltematives include two commQD features: . '
(1)
Groundwater Monitoring'
A long-term monitoring program would be instituted using both on- and off-site wells to
measure the effectiveness of the remedial action during implementation.
.
, -
-------
.
McChord AFB Area DI ALGT ROD
Page
73
If additional existing private drinking water wells are found to be potentially affected by
the contaminant plume, remaining residents of ALGT will be offered connections to the
Lakewood Water District supply system. The Air Force will update the affected
communities as the remedial action progresses and monitor the contaminated private
wells.
(2)
Institutional Controls
Administrative and institutional controls will include provisions for permanent alternate
water' supply, access restrictions, notification to appropriate agencies, and public
awareness. In addition, appropriate controls would be described in a restrictive covenant
on the Area D property and would be recorded with the register of deeds for Pierce
County. Thi~ restrictive covenant would run with the land and be binding on McChord's
successors and assigns. Although the baseline risk assessment determined that no
unacceptable risk exists in the soil for future residential use, McChord AFB direc~ves
would specifically prohibit future development of landfills 5, 6, 7, and' 39 for human
habitation, as an added precaution. The McChord AFB directives would also restrict the
, uses of S~allOw groundw~ter within Area D.
, '
.
,
1.
No Action (monitoring only)
The NCP requires that the "no action" alternative be considered for every site ~o
~etermine a, baseline against' which other remedial alternatives can be, m~ured. Under
this alternative, no remedial actions would be taken beyond those already in place (i.e.,
p~~viding' a.n alternative ,water supply to resid,ents with contaminated wells)., Monitoring
would be 'impl,emented'onlY:to'evaluate c~anges in the Contaminant plume.. .
2.
One Groundwater Extraction System. One Carbon Adsoq>tion Treatment Facility.
and IrrigationlRecharge of Treated Groundwater
"
. '.' . '..
. ., .
'IJ1e pu~se: o~ this alternative is to' create a hydrologic barrier to prevent further off-base,.
migration of contaminated groundwater at concentrations above the MCLs andcontairi the'
contaminated plume on-site. The alternative consists of a single extraction system that
will extract the contaminated groundwater from one or more wells located near the
western property boundary of McChord AFB. The extracted groundwater would be
-------
McChord AFB Area DI ALGT ROD
Page
74
_flowrate of 100 gallons per minute (gpm) and an influent TCE concentration of 10 ugll,
_the carbon adsorption unit should treat the TCE to less than 0.1 ugll.
,The carbon adsorption system would bring the contaminated groundwater into direct
contact with activated carbon by passing the water through the beds of caIbon. The
activated carbon selectively adsorbs hazardous organic chemicals. Used carbon would be
recycled through combustion off-site at a facility operating in compliance with EPA's
Off-Site Disposal Policy.
The treated groundwater would be tested for compliance with the effluent standards.
Depending on the season of the year, treated groundwater would either be used for
" .irrigation of the golf course or would be recharged back to the ground into a passive
recharge system downgradient of the extraction well. The exact number and location of
extraction wells and recharge systems would be determined during design.
Under alternative 2, further off-base migration of the plume would be prevented.
However, the plume would not be remediated on base and would remain in the
unconfmed aquifer, on base for-the foreseeable future.
- -
, , J:b,e reaSonable maximum exposure' ~>. ~or ~e off.-base resident after remediation, '
. ' under ~s,scenario presents a combll.tedresid~ ~sk 'at remediation go~s',for al1_Si~ '
, ", ' related' ContaminantS ~d all pathways of IE:.05 (~cirio~eiiic risk) and "a hazard' index of ,
, 0.04 (Iion-carc~~~~nic risk). The resi~ua1 risk for a future use on-base ~ident would
be equal ~o the baselirie risk of 2E-04 (carcinogenic'risk) and a, h~d index of. 1.01
" , (nonc3rcmogeni~ risk).:., ' . - :~, ... ,... ,:' .,:
, " ,3." Three Grou,ndwa~er Extra~tion,Systems. Two Carbon Ad~tption Treatment
Facilities. and Irrigatiori/Recharge of Treated Groundwater'
, ' '
The purpose of this alternative would be to create a hydrologic b~er ,to prevent further
off-base migration of contaminants at concentrations above the MCLs and to treat the
. -most contaminate4 groundwater,J>eneathjbe',,~, D si~.: ~s ~~~ative ,e~pec~ ,~,
remedlate the oontaminatedplume off-site ~don-site,.', " ",'
This alternative consists of three groundwater extraction systems, each consisting of one
or more wells: one located near the western property boundary of McChord AFB; one
located in the north portion of the contaminant plume; and one located near Sites 5 and
39. The extracted groundwater would be pumped to two multi-bed carbon adsorption
.
. . .. ~ .
..
-------
McChord AFB Area DI ALGT ROD
Page
75
facilities for treatment. Assuming a flow rate of 100 gpm and an influent TCE
concentration of 8 ug/l, the carbon adsorption unit at Treatment Plant 1 (near the western
property boundary of McChord AFB) should treat the TCE to less than 0.1 ugll.
, Assuming a flowrate of 200 gpm and an influent TCE concentration of 48 ugll, the
carbon adsorption unit at Treatment Plant 2 (near Sites 5 and 39) should treat the TCE to
less than 0.1 ugll.
The treated groundwater would then be tested for compliance with the effluent standards.
Depending on the season of the year, treated groundwater from Treatment Plant 1 would
either be used for irrigation at the Whispering Firs golf course would be recharged back
to the ground into a recharge system down gradient of the extraction well. The exact
number and location of extraction wells and recharge systems would be determined
during desig~.
The treated groundwater from Treatment Plant 2 would be recharged back to the ground
through upgradient recharge trenches or wells to further enhance groundwater cleanup by
flushing the treated groundwater through the deeper zones of, the contaminated aquifer
where areas, of higher CQncentrations, of TCE an'd DCE may exist. The exact number and
. l~tion ~f e~tIaction wells, and recharge systems '-\vouid be' dete~ed during design. '
Under Alternative' 3, remediation 'of Area D/ALGT'contaminated groundwater plume is
expected to require a minimum of SO, years.
, '
The' r~nable maximum 'exposure' (RME) for the',off-baSe resident after remediation
under this scenario presents a' combined residual risk of lE-05 (carcinogenic risk) and a
, h~d index of ().Q4 (non-carcinog~nic risk) after achi~ving r~mediation goals for all site- ,
related contaminants and all pathways. ' '
4. Three Groundwater Extraction Systems. Two Carbon Adsot:ption Treatment'
, .
, ,Facilities with the Addition of Bioremediation. and IrrigationlR~harge of Treated
',', "":, "Groundwater ,', '..' . ., '
, , ,
, ,
"
"
The groundwater extraction and carbon treatment schemes for this alternative are the '
same as Alternative 3.' However, at the carbon treatment facility located in the vicinity
of Sites 5 and 39, a supplemental biological treatment system would add nutrients and
oxygen to the treated groundwater. Nutrients and oxygen may stimulate the growth of
bacteria in groundwater which are capable of breaking down TCE and DCE. Five wells
-------
.
McChord AFB Area DI ALGT ROD
Page
76
would recharge the nutrient-rich groundwater into the area of the plume with the highest
concentrations of contaminant.
In-place bioremediation technology-is a developing innovative technology and its
reliability is not known. Therefore, experimental testing would be necessary to determine
its effectiveness within Area DI ALGT. The use of this technology has been limited to
relatively small areas due to .the difficulties involved in delivering nutrients and oxygen-
rich water to the contaminated areas. Treatment of an entire plume is not considered
feasible. In addition, the success of bioremediation is questionable for the relatively low
levels of VOC-contamination (e.g., 70 ug/l TCE maximum) found at the Area DI ALGT
site.
Under Alternative.4, remediation of the contaminated groundwater plume may be less
than 50 years, but significant additional research and pilot testing would be required to
demonstrate this.
The ~nable qtaximum exposure (RME) for the off-base resident after remediation
under this scenario presents a combined residual risk of lE-05 (carcinogenic risk) and a
~~ index of 0.04 (non-carcinosenic risk) after achieving remediation goals for all site-
.. n:iated oonjaminants andaI1 pa~ways. .' ... .. . .
. ...,
ARARs in the Description of Alternatives
- The prin~ipa1'ARARs' for .all of'the groundwa~~ alternatives ab.ove are. ~e. ~ed~~. Clean
Water Act (CWA) (33 uSc 1251), the Safe Drinking Water Act (SDWA) (40 .
. . .
. .
USC 3(0), the Resource Conservation and Recovery Act (RCRA) (42 USC6901); the .
. .
Water Pollution Control Act (Chapter 90.48 RCW), and the State of Washington Model
Toxics Control Act (Chapter 70.105D RCW)~ .
. . Under the CWA:
.'
.. ," ."
. .
..
. ."
."..
(1) State Anti-degradation Requirements/Use Classification require every state to
classify all the water within its boundaries according to intended use. The aquifers
beneath Area D/ALGT, including the contaminated unconfined aquifer, are Class n (Le.,
drinking water) aquifers;
;. .
-------
McChord AFB Area DI ALGT ROD
Page
77
(2) CW A section. 304 specifies ambient water quality criteria (A WQC) which were
developed for the protection of human health and aquatic life. The A WQC were
compared to contaminant levels found in surface waters potentially affected by Area D
(Table 4A) and are discus~ further in the section entitled Environmental Risks; and
(3) CWA section 301 (b) requires that, at a minimum, all direct discharges meet
technology-based limits for conventional pollutant control technology. Sinc:e remedial
actions at CERCLA sites need meet only the substantive requirements of the National
Pollutant Discharge Elimination System (NPDES) regulations; effluent limits are
determined on a case-by-case basis using best professional judgement. Carbon adsorption
was the ~ of pollutant control technology evaluated for the groundwater alternatives.
Carbon adsorption is an available proven technology for treatment of VOC-contaminated
groundwater.. .
CERCLA section 121(d)(2)(A) requires on-site CERCLA remedies to attain standards or
levels of control established under the SDW A (Le. MCLs or MCLGs [maximum
contaminant level goals]). According to the NCP (55 FR 8848), where MCLGs are set at
~ro, the remedial actions shall attain MCLs for groundwate~ that are current or
potential. sources of drinking water..
Since. the sOurce of halogenated. solvents could not be made; TCE arid DCE are no~
classified as RCRA-listed spent halogenated solvents (FOOI-FOO5).. Consequently, the
gro~nd~ater is not contaminated with a RCRA listed waste. TCE.and DCE would only
be subject to LDR'.s if determined to be a characteristic waSte.. .
. The requirements. of .the Department ~f Ecology .Dangerous Wast.e Re~.u~ations (WAC
173-303-170) for genefatoiS'of dangerous waste would apply for removat of spent carbon
generated during carbon adsorption of the groundwater contaminants.
The MTCA compliance cleanup levels for groundwater are determined by one of the
. following methods: . (1) .~e calculated .levels usj.ng. ris~ equa~ons iri WAC 173-~ 720,
.(2) concentrations established .by applicable state and federal. regulations, (3) . ..
concentrations which are anticipated to result in no acute or chronic toxic effeCts on .
human health, and (4) concentrations which are anticipated to result in an ~xcess lifetime
cancer risk less than one in one million. The total excess lifetime cancer risk shall not
. .
exceed one in one hundred thousand and the hazard index for substances with similar
non-carcinogenic toxic effects shall not exceed one.
-------
MeChord AFB Area DI ALGT ROD
Page
78
vm. SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
The remedial alternatives for the MeChord AFB Area DI ALGT site were compared
according to nine criteria developed on the basis of statutory requirements of CERCLA
Section 121 and the NCP. The nine criteria are subdivided into three categories: . (1)
threshold criteria which relate directly to statutory findings and must be satisfied by each
chosen alternative; (2) primary balancing criteria, which include technical factors such as
the long and short term effectiveness, implementability, reduction of toxicity, mobility,
and volume and cost; and (3) modifying criteria, which are measures of the acceptability
of the alternatives to state agencies and the community. The following sections
summarize the evaluation of the candidate remedial alternatives according to these
criteria. Table 15 includes a summary of the comparative analysis, or relative ranking,
of the alternativ~.
A.
Threshold Criteria
,
1.
Overall Protection of Human Health and the Environment
This criterion measures how the alternative, as a whole, achieves and maintains
. protection .of hu~an.heaIth and. the envirC?nment.
'.
.' . '", . . .
. .' .
. ..' .'
.. The -no. action';' aliernative'is:hotprotective of. human' health ortheenvironment because, :
it d~ 'not prevent the migration of contaminants to the lower aquifer. Also, this
.. alte~ative does not change. con~ant concentrations ~r e~posure, the :residual ri~ is
'.. . equivalent to tJie' baseline risk.; .'.. . .' .
~ternati.v~s. 3 and 4 provide a high~r}evel of pro~tion in a shorter time .~
Alternative 2.' Alternatives 3 and 4 reduce the residual fisks to residentS and workers on-
. .
. site and off-site because it is designed to remediate the plume on and off the Air .Force
base property. Alternative 2 does not include treatment of groundwater beneath the Air
Force base property and, therefore, is not protective if this groundwater is used for
:. drinking. water. Under.Altemative.2 ri$to:.oI).-site resid~nts andwo(kers rem~
identi~ to those ~ICulated iD. the baseline risk. 'as~ssme~t. .' . .. ':." .
. .
c
- ", .
-------
.
Page 79
Table 15. Summary of Alternative Analyses.
4:
Extraction
2: 3: Scheme 2.
Extraction Extraction Carbon
Scheme 1. Scheme 2. Adsorption. In-
Carbon Carbon Situ Bio-
I: Adsorption and Adsorption and remediation.
o Criteria No Action Recharge Recharge and Recharge 0 "
Short-Term
Effectiveness During
Construction N/A High High High
Long-Term
Effectiveness Low Medium High High
Reduction of Toxicity.
Mobility, and Volume Low Medium High o High
Implemenubility N/A High High Low
.
Compliance with
ARARs Low Low High High
Protection of Human
Health and Environment Low Medium" High High
State Acceptance Low Low High Medium
Com.m~nity AC~eptance11 00
0 Capital Cost $306,500 $831,2000 0 00 $l,407,400 0 0$1;641;000
Operating Costs $45,000/y~ $139, OOO/yf' $341,000/yf' $409 ,OOO/yf'
$22,500/yr" $117,000/yr" $318,000/yr" $386,000/yr"
Net°Pres.e~t Worth $558,000 $1,972.000 $4,445,000 $6;089.000
(i=10%, n=30. yrs)
Net Present Worth $738,000 $2,896,000 S6,9~9.000 0 $9,899.000
o (i=4%, n=30 yfs)
N/A: Not Applicable 0 0
11 Support agencies and community acceptaIice will be discussed in the Responsiveness
Summary .
" 2l o. 0 Op~rating <;:ost for first 2 years. 0... .0. o. 0 00
3/ qperating ocost fororemaining 28 years. :
o 0
"0
o .
.-
-------
McChord AFB Area DI ALGT ROD
Page
2.
Compliance with ARARs
Compliance with ARARs is a consideration of how the alternatives comply with waste
regulations that explicitly apply to the site and those regulations that are sufficiently
relevant to warrant inclusion. In some extenuating situations, waivers from selected
ARARs may be obtained.
Alternative 1, does not comply with ARARs. Contaminated groundwater would continue
to exceed maximum contaminant levels (MCLs) and would likely contaminate additional
drinking water supplies. Alternative 2 does not comply with ARARs. Although some
clean-up. of contaminated groundwater is achieved, the remaining contamination (under
Area D on the Air Force base) exceeds MCLs.
Alternatives 3 and 4 provide similar compliance. with AR~Rs. Contaminated
groundwater is removed and treated, and further migration is limited. One potential
point of non-compliance is the inj~tion of biological agents into the sub-surface under the
bioremediation Alternative 4. -However, a waiver may be obtained for this activity
because it may assist in the remediation.
B. . Primary BalancIng Criteria .
.' .
3.
., .
. .
" LOng~term Effectiveness and Permanence
. TJ:lis'crltenon 'evaluates.th~ long~teqn effectiyeness of a1ternativ~~ in maintainiitg
pro~ti~n 'of human health and the envi~onment 'after remedi~ action objectiv~s have,
been met.
Alternatives 3 and 4 provide a higher degree of long-term effectivenes~ and Permanence. . .
than. either Alternative 1 or 7. The risk of contaminating the deeper . potable aquifer
would still remain at the site after the response actions of Alternatives 1 and 2. Neither
. .~terriativeremediates the contaminated plume. .And the risk of contaminating the deeper
'. . potable aquifer. would remain'~ " . . . ....',' .: '.' .
4.
Reduction of Toxicity. Mob iJi ty . or Volume Through Treatment
Alternatives were also evaluated according to their ability to reduce the toxicity, mobility,
or volume of contaminants through treatment.
.
80
.
.- .
-------
McChord AFB Area DI ALGT ROD
Page
81
,
Alternatives 3 and 4, with more aggressive extraction and treatment systems, meet the
preference for treatment to reduce the toxicity, mobility, and volume of the contamination.
more effectively than Alternative 2. Alternative 1 does not reduce these properties of the
contamination. .
s.
Short-term Effectiveness
This criterion addresses the effects of the alternatives during the construction and
implementation phase until remedial action objectives are met.
None of the alternatives evaluated are expected to pose risks to human health (e.g.,
workers) during construction or implementation. Any risks during construction can be
adequately controlled with engineering controls and standard health and safety practices.
Alternatives 3 and 4 provide greater short-term effectiveness by remediating the
groundwater significantly faster than Alternatives 1 or 2, neither of which are expected to
achieve remedial action objectives in the foreseeable future.
6.
Implementability .
. ..
.This criterion addresses the technical and administrative feasibility of implem~nting.the
alternatives and the availability of services and materials required during implementation.
Altep1atives 2 and 3 ~e readily implementable using available tec~ology.. . .
Construction of extraction and recharge systems and installation of carbOn adsorption
units would not be difficult... Equipment and specialists are readily available for .these
well developed technologies. Additionally, there should be no difficulty in obtaining any
permits that may be required during design and construction.
Alternative 4 includes a developing, innovative technology and its reliability and
. . implemen~bility: are. n~t yet known. . The. :in$itu. biorem~~ation ~f g~und~~r .~ui~s.a ..
complex delivery system and has not been demonstrated to be effeCtive on groundwater ;-
-------
McChord AFB Area DI ALGT ROD
Page
82
7.
~
Cost is another criteria by which candidate alternatives are compared. Costs in this case
are measured as capital, operation and maintenance (O&M), and present worth costs. A
summary of these costs for each of the alternatives is included in Table 15.
Alternative 2 is the least expensive of the treatment alternatives and is roughly one-half
the cost of Alternative 3 and one-third the cost of Alternative 4.
C.
Modifying Criteria
Modifying criteria are used in the final evaluation of the remedial alternatives, and
include comment from Ecology and from the public.
8.
State AcCe.ptance
The State of Washington Department of Ecology (Ecology) concurs with the preferred
remedial al~mative., Ecology has been involved with the development and i'eview. of the
Remedial Investigation, Feasibility Study, Proposed Plan, Record of Decision, and,other
. project ',ac~vities such as public meetings. . .
9.
, '
, .
. . . . .
"CommunitY 'A~tance ';'
, .
" '
"
. ~ o~ v~ibalcomnients'received during the pu~lic meeting held April 11, ~~1 and
. written Comments 'feceived dunng the comment period ending. May 8, '1991, 'the'. ..'
community appean to accept the preferred remedial alternative. Specific responses and
. .
. .comm~nts to,the rem~ alternatives may be found in the, attached RespoJlSi~eness
Summary. '
IX. THE SELECTED REMEDY
, . ..,~ 'o~ ~.~ and the .BaSefuie Risk, ~ssessment, it w~ dete~ed 'that no ~medial.
, action is necessary for soil, surfaCe waier, or sediment to,ensure protectiol) or'hu~
health and the environment. '
Th~ selected remedy for the contaminated groundwater is Alternative 3 - Installation of
Three Groundwater Extraction Systems, Two Carbon Adsorption Treatment Facilities,
.
". : .
.
-------
c
McChord AFB Area D/ALGT ROD
Page
83
and IirigationlRecharge of Treated Groundwater. This remedy addresses the risk posed
by . the contaminated groundwater through treatment which permanently and significantly
reduces the volume, toxicity, and mobility of the hazardous substances.
.
A. MJqor Components or the Selected Remedy
The major components of the selected remedy include:
.. . .
. ..'-
.
Install groundwater extraction wells capable of capturing the groundwater
contaminant plume in the unconfined aquifer. An estimated three extraction
systems will be necessary to achieve this goal.
.
Install one of the three groundwater extraction systems near areas of highest
concentration of contaminants within the contaminant plume.
.
Install on-site groundwater treatment facilities to remove contaminants from
th.e extracted groundwater. The preferred treatment is cart:x>n adsorption,
with an estimated two treatment facilities necessary to achieve this g03l.
. .
. Moni~w:.~e gr01iQdwatercontariunaIit pl~me an~. ~e e~~ctionltreatrrient..
sys.teni during ground~tet remediation .~(:tiyities to ensure .~at grpund~ter .
remediation goals are achieved and maintained throughout the cOn~t
plume.
"., .
.
Implement administrative and institutional controls such as restrictive
covenants and McChord Air Force Base command directives, that supplement
. engineering controls and ininimii.e exposure to releases of hazardous
substances during remediation.
The goal of this remedial action is to restore groundwater to its beneficial use, which is,
at this site, a .potenti~ .d~ng. w~Jer source. by . ~t.taining- d1j~ng water standards
. .' '", .' I . ," .' "'. . . '.
. . tJ:lroug~out the groundwater aquifer. Based o~ i,Dfonnati~n obtained during the remedial. .
investigation and on an analysis of all remedial alternatives, the Air Force, EPA, and. th~'
Ecology believe that the selected remedy will achieve this goal. It may be apparent,
during implementation or operation of the groundwater extraction system and its
modifications, that contaminant levels have ceased to decline and are remaining constant
-------
McChord AFB Area DI ALGT ROD
Page
84
at levels higher than the remediation goal over some portion of the contaminant plume.
In such a case, the system performance standards and/or the remedy may be reevaluated.
The selected remedy will include groundwater extraction for an estimated period of 50
years, during which the system's performance will be carefully monitored on a regular
. .
basis and adjusted as warranted by the performance data collected during operation.
Modification may include any or all of the following:
.
Discontinuing pumping at the individual wells where cleanup goals have been
attained. .
.
Alternating pumping at wells to eliminate stagnation points.
.
Pulse pumping to allow aquifer equilibration and to allow adsorbed
contaminants to partition into groundwater.
.
Installing additional extraction wells to facilitate or accelerate cleanup of the
. contaminant plume. ' . , .
It may also~me app~nt during d,~ign, implementa~on, or operati~n of the effluent
. recharge system:'tha( the system'is not effective. For e~ainple, the recJtarge piping may: .
clog' becauSe of the natural water chemistry or the' dis~rbed: soils may. prevent effective,
infIluition. In such a case, the recharge system may be reevaluated. If neces~, other
.. alternatives for effluent recharge would be considered (e.g., dischar~e to surface water).
. Requirements for effluent discharge must .then satisfy tl)e subs~tiv~ prC?Visi6~s of the ','
National Pollutant Discharge Elimination System (40 CFR Parts 121-125). '
. .
. ".' ., '.'. ..'~ .~. ~,.? '. . . . - - ". .... . ..:~:.~':'., .
To ensure that cleanup levels are maintained,- 'the aquifer will be monitored' annUally at '
those wells where pumping has ceased following discontinuation of groundwater' '
extraction~ 'and 'at groundwater ,monitoring wells located throughout the site. .
, ,
'The residual spent carbon ,wm be transpoJ1ed off-site for reg~ne~tion (e.g., through. ,
~mb\istion) ~t a faC,mty, o~rating' in cPinplian~ ~th .BFA' s, Oif~Site Dispo~ Poli~y ~ :"
No other residuals from the treatment process are anticipated.
.
.
,.
, ,
~
-------
McChord AFB Area DI ALGT ROD
Page
85
t
..
Post-ROD studies prior to remedial design may include a bench-scale treatability study to
obtain info~ation to design the carbon adsorption system. In addition, pump tests may
be required to obtain engineering data for design of the extraction, and discharge systems.
,B. Remedial Action ObjectiveslRemediation Levels
The risk assessment concluded that groundwater contamination originating from Area D
presents a threat to human health and the environment. Existing conditions at the si,te
pose a threat predominantly from ingestion and vapor inhalation exposure to'" ", '
VOC-contaminated groundwater.
The objective of the remedial action is to restore groundwater to its beneficial use, a
drinking water source. The groundwater will be restored to levels consistent with state" ,
and Federal ARARs. Remediation levels will be attained throughout the contaminated
plume.
Remediation goals were established for contaminants of concern with levels that either:
(1) exceed an ARAR or (2) are not protective of human health and the environment.'
- -
Remediation goals were not established for metals measured at levels determined to be : .
consistent With natu,rally Occurring background concentrations~ 'Remediation goals have
been established as shown in'Table 16.
~
, "
.
Of the contaminants that present risks b~ on current and future land use, site
concentrations of arseniC an,d manganese were found' to be consistent with naturally
occurring background concentrations. Thallium presented a risk based on the result of
one ,sample; ,this anaJ-yticalresult is thought to be err()n~us. ,C?,r ~e remainin~ '
contaminants, styrene, beta-BHC, chlordane, dieldrin, and 4,4'-DDT were never de~ted
in the grouiid~ater during the RI. <:Jroundwater was idei1ti~ed as the critical' exposu~ "
pathway for th'esecontaminants. Methylene chloride and bis(2-ethylhexyl) phthalate were
determined to be laboratory contaminants and therefore do not present a risk. The'
,remaining organics for which remediation goals were not 'set were '~etected" infrequently,
and 'at low cOncentrations. These compounds do' not currently excee
-------
, "
Table 16. Remedial Action Objectives.
RME Concen-
tration in, "
Groundwater, ,
, (pg/l)
Contaminant
.'
Media,
: :'Remedi- '
, 'ation
Goal
. (pg/l)
Basis
Remedial Action
Objective
Reason
TCE
cis-I,2-DCE "
Vinyl Chloride'
1,I-DCE .
Groundwater
Groundwater
Groundwater
Groundwater
MCL
GWCL
MTCA
RME
76
222
0.7
"
"
0.41
. 5
MCL
70
..MCL
Pump and treat,
groundwater monitoring
Pump and treat,
groundwater monitoring
Pump and treat,
groundwater monitoring
Pump and treat,
groundwater monitoring
Exceeds MCL, MTCA,
GWCL
Exceeds MCL In
groundwater
Exceeds MTCA Method B
GWCL
Exceeds MTCA Method B
GWCL
MTCA Method
, B detection limit
(EPA Method
'. 524.2)
. . .07 . , 'MTCA Method
'B
0.04
, .
. , Maximum Contaminant Level (froin Safe, Drinking Water Act)
, ' Groundwater cleanup level' ' ,
, ~odel Toxics Control Act
'~easonable Maximum Exposure
..
.' ",
'.
, .
.'
'\ :
. .
~
..
i
00
0\
.
..
-------
McChord AFB Area DI ALGT ROD
Page
87
..
Residual risks from the remediated groundwater at these remediation goals were evaluated
for current off-site residents and future on-site workers following remediation. Relevant
exposure pathways included ingestion of drinking water and inhalation of volatiles while
showering. The results of these analyses using EPA Region 10 exposure parameters and
, risk assessment guidance are summarized as follows:
.
Current Off-site Residents; cancer- lE-S, non-cancer- 0.04.
Future On-Site Workers; cancer- 8E-6, non-cancer- 0.12.
.
Cancer risks for off-site residents for groundwater ingestion and inhalation will be
reduced by approximately 50 percent when compared to risks calculated in the Baseline
Risk Assessment. The hazard index for off-site residents based on meeting remediation.
goals a.'ld reasonable maximum exposure concentrations was 0.04.
For the future on-site worker, cancer risks and hazard indices for groundwater ingestion
and inhalation will be reduced by approximately 80 percent after remedial goals for
groundwater treatment are achieved.
Risks to any. future on-site residents from groundwater expos~res, \Vill be further mitigated
. . ~ough mstitutibnal Controls and deed ,restrictions' which will.be strictly' enforCed by the' ,
. Air Force. .' . . .'
x. THE STATUTORY DETERMINATIONS
The selected remedy meets the statutory requirement of Section 121 of CERCLA, as
amended by SARA, and to the exte~t practicable, the National Conti~gency Plan.'
. . . .' . . .'
. .
,A; :Protection of Human Health and the Environment
,
The selected remedy reduces the risk posed by the contaminated groundwater and will
attain a 10-4 to 1
-------
McChord AFB Area DI ALGT ROD
Page
88
B.
Attainment of Applicable or Relevant and Appropriate Requirements (ARARs)
of Environmental Laws
The selected remedy will comply with all applicable or relevant and appropriate
requirements (ARARs) of Federal,. as well as more stringent, promulgated State
environmental and public health laws.
1.
Applicable or Relevant and Appropriate Requirements
Action-Specific
State of Washington Hazardous Waste Management Act (Chapter 70.105 RCW)
requirements for dangerous waste and extremely hazardous waste as codified in Chapter
173-303 WAC.
State of Washington requirements for Water Well Construction (Chapter 18.104
RCW)as codifiedin Chapter 173-160 WAC.
i .
I .
. .
, .~. . .. . . . . . .
State of Washington requirements (Chapter 173-154 WAC) for the management of
groundwater. in a manner that ~rotects, t~ .the extent practicable! the upper aquifers of .
. multiple aquife~. syst~ms (ro~ depletjoIis~ excessive water lev~l dec1iftes or reduc~ons in: . '.
water quality; .. '. . ...' . .
. .
Water Pollution Control Act (Chapter 90.48 RCW), Pollution Disclosure Act of
- '197l-(Chapter 90.52), and.Water Resour~s Act of 1971 (Chapter90.~4 RCW) require
. .
the use of all known, available, and reasonable methods (AKARTs) of treatment prior to
'. ~ischar,ge. to groundwater.
. .~equire~ents of the Clean Water Actsection~. (40 ~~.p~ 121:-125) for
."effluent discharge. would be applicable if it is necessary to uSe an- alternate effluent" .
discharge system.
. .-.
.: '#' I . . . '. . " .... .' .
. RequirementS of the State Waste Di~haige Pe~t Program' (Chapter. 173-216.
WAC) for discharge of waste materials into groundwater.
..
t
..I
-------
..
.
McChord AFB Area DI ALGT ROD
Page
89
.
State of Washington requirements for hazardous waste operations conducted at
uncontrolled hazardous waste sites as set forth in WAC 262-62 Part P (Hazardous Waste
Operations and Emergency Response).
,
Chemical-Specific
Federal requirements of the Safe Drinking Water Act (40 USC 3(0) {or
groundwater used as drinking water, as set forth in 40 CPR 141.
. State of Washington Hazardous Waste Cleanup - Model Toxics Control Act
(Chapter 70.105D RCW) requirements {or the identification, investigation, and clean up
of hazardous waste sites as codified in Chapter 173-340 WAC.
Substantive water resource antidegradation fundamentals of the State of Washington
Pollution Control Act (Chapter 90.48 RCW) and Water Resources Act of 1971 (Chapter
90.54 RCW).
,
.
-: Water Pollution Control Act (Chapter 90.48 RCW), P01lution Disclosure Act of
.: 1971 (Chapter 90.52), and Water Resources Act of 1971 (Chapter 90.54 RCW). reqU:ire
the use of all known, .available, andieasonable methods (AKARTs) of treatment .prior to
. discharge to groundwater.
Location-Specific
There are no location-specific ARARs identified for Area DI ALGT.
-- ~:6~'\..
2.. . To..Be-Consldered
There are no To-Be-Considered guidelines identified for Area D/ALGT.
~
. .. c.
Cost Effectiveness. .
. t..
. ,;,.
1
The selected remedy is cost-effective and provides overall effectiveness propOrtionate °to .~
-------
.McChord AFB Area D/ ALGT ROD
Page
J
90
D.
Use of Perma~nt Solutions and Alternative Treatment T~ologi~ or
Resource Recovery T~ologies to Maximum Extent Practicable
The Air Force, EP A, and Ecology have determined that the selected remedy represents
the maximum extent to which permanent solutions and treatment technologies can be used
in a cost-effective manner for the Area D/ALGT site. The risk from the groundwater
contamination is permanently reduced through treatment
to acceptable exposure levels without transferring the risk to another media (e.g., air).
The selected remedy provides the best balance of tradeoffs in terms of long-term
effectiveness and permanence, reduction in toxicity, mobility, or volume achieved
through treatment, short-term effectiveness, implementability, and cost.
Also State and community acceptance were considered.
E.
Preference for Treatment as Principal Element
,
On-site treatment of the VOC-contaminated groundwater using carbon adsorption satisfies
the statutory preference in whi~h treatment, as a principal element, permanently and
significantly reduces the'volume, toxicity, or mobility of the hazardous substances. '
xI. DOC1)MENTATlO~ OF SIGN1FICANT CHANGES, ' ,
. . . .
, , The PropoSed Plan' for Area])/ALGf was: 'released for public comment in M~ch 1991. .
The Proposed Plan Identified Alternative 3, extraction and on-site treatment of VOCs in
the groundwater, as the preferred alternative. Upon review of public comment, it was
determined that no significant changes to the remedy, as it was originally identified in the
Proposed Plan, were necessary.
,.
..., .
'." '.
. ," ..
. .
.
.
~
.. .'
,
,-
'...
------- |