EPA/ROD/R10/94/094
February 1995
EPA Superfund
Record of Decision:
Umatilla Army Depot (Lagoons),
Operable Unit 3, Hermiston, OR
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DEFENSE ENVIRONMENT AL RESTORATION
PROGRAM .
FINAL RECORD OF DECISION
UMA TILLA DEPOT ACTIVITY
EXPLOSIVES WASHOUT LAGOONS GROUND WATER
OPERABLE UNIT
June 7, 1994
In accordance with Army Regulation 200-2, this document is intended by the Anny to
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Table of Contents
List 01 Figures and Tables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Acronyms and Abbreviations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.0 Declaration of the Record 01 Decision. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
II
1
2.0 Decision Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 9
2.1 Site Name, Location, and Description. . . . . . . . . . . . . . . . . . . . . . . . . . ., 9
2.2 Site History and Enforcement Activities. . . . . . . . . . . . . . . . . . . ., . . .. 12
2.3 Highlights of Community Participation. . . . . . . . . . . . . . . . . . . . . . . . ., 13
2.4 Scope and Role of Operable Unit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . ., 14
2.5 Site Characteristics and Environmental Investigation Results. . . . . . . ., 14
2.6 Summary of Site Risks ....................................... 21
2.6.1 Human Health Risks' .................................. 21
2.6.2 Environmental Evaluation. . . . . . . . . . . . . . . . . . . . . . . . ., . . ., 31
2.7 Description of Alternatives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ., . 31
2.7.1 Ground WaterOeanup Levels................"'" .., .., 32
2.7.2 Alternative Descriptions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . ., 34
2.8 Summary of Comparative Analysis of Alternatives. . . . . . . . . . . . . . . .. 47
2.8.1 Protection of Human Health and the Environment. . . . . . . . . .. 47
2.8.2 Compliance with ARARs ............................... 48
2.8.3 Long-Term Effectiveness. . . . . . . . . . . . . . . . . . . . . . . . . . . . . ., 49
2.8.4 Reduction of Toxicity. Mobility, or Volume through Treatment 50
2.8.5 Short-Term Effectiveness. . .., . . . . . . . . . . . . . . . . . . . . . . . . .. 51
2.8.6 Implementation. . . . . . . . . . . . . . . . . . . . . . . ; . . . . . . . . . . . . :. . 51
2.8.7 Cost. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 52
2;8.8 State Acceptance. '. . . . . . . . . . . ~ . . . . . . . . . . . . . . . . . . . . . . .. 52
2;8.9 Public Acceptance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 52
2.9 Selected Remedy. . . . . . . . . . . . . . . . . . . ., . . . . ; . . . . . . . . . . . . . . . . .. 53
2.10 Statutory Determinations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 54
2.10.1 Protection of Human Health and the Environment...... ..... 55
2.10.2 Compliance with ARARs ...........................:... 55
2.10.3 Cost............................................... 57
2.10.4 Utilization of Permanent Solutions and Alternative Treatment
Technologies or Resource Recovery Technologies to the
. Maximum Extent Practicable....... . . . ." . . . . . . .. . . . . . ... 58
2.10.5 Preference for Treatment as a Principal Element. .". . . . . . . . . .. 58
2.11 Documentation of No Significant Changes. . . . . . . . . . . . . . . . . . . . . ., 59
3.0 Responsiveness Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
60
Appendix A:
Appendix B:
Oregon DEQ Letter of Concurrence
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List of Figures and Tables
Figure
Page
1
2
Facility Location Map, Umatilla Depot Activity. . . . . . . . . . . . . . . . . . . . . . . 10
Location of Explosives Washout Plant and Washout Water Sump. . . . . . . . . 11
3
Stratigraphic Cross-Section Beneath UMDA Washout Lagoon. . . . . . . . . . . 15
Simulated and Observed RDX Ground Water Contaminant
Concentrations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 18
4
Simulated and Observed TNT Ground Water Contaminant
Concentrations, . . . . . . . . . . " . . . . . . . . . . . . . . " . . . . . . . . . . . . . . . . . . . . . . . 20
6 'Conceptual Flow Diagram of UV Oxidation of Contaminated Ground
Water.. [[[ 37
5
7
Conceptual Flow Diagram of Primary GAC Treaanent of Contaminated
Ground WatJ:C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Table
page
1
Summary of Contaminants of Concern m the Ground Water at the
Explo&vesWashoutLagoons...................................... 17
Physical and O1emica1 Properties of the Explosives in Washout Lagoon
Ground WatJ:C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2
3
Summary of Toxicity Criteria for the Contaminants of Concern in Washout
Lagoons Ground Water. . . " . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Quantitative Summary of Daily bitake for Ground Watt:! Ingestion.. . . . . .25
4
5
Quantitative Summary of Daily Intake for Dermal Absorption of.Ground
Water. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Quantitative Summary of Daily Intake for Crop Ingestion. . . . . . . . . . . . . . . 28
6
7
CaIcinogenic and Non-carcinogenic Hazards Future Residential Land Use
Scenario. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Remedial Action Criteria for the Ground Water at the Explosives Washout,
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Acronyms and Abbreviations
ADA
ARARs
BRAC
CERCLA
CFR
cy
DNB
2,4-DNT
2,6-DNT
DoD
EPA
EPIC
EWL
FFA
FS
GAC
HBRA
BEAST
III
HMX
HRS
IRIS
MCL
NA
NB
NCP
NEPA
Ammunition Demolition Area
Applicable or relevant and appropriate requirements
Base Realignment and Closure
Comprehensive Environmental Response, Compensation, and Liability
Act of 1980 . .
Code of Federal Regulations
Cubic Yards
1,3-Dinitrobenz.ene
2,4-Dinitrotoluene
2,6-Dinitrotoluene
Deparanent of Defense
u.S. Environmental Protection Agency
Environmental Photographic Inte~tation Center
Explosives Washout U\goons
Federal Facility Agreement
. Feasibility study
Granular activated carbon
Human health baseline risk assessment
Health Effects Assessment S'Jrnmary Tables
Hazard Index
Qctahydro-l,3,5,7-tetranitro-l,3,5,7-teuazocine (High Melting
Explosive) .
Hazard Ranking System
Integrated Risk Information System
Maximum contaminant level
Not applicable
Nitrobenzene
National Oil and Hazardous Substances pollution Contingency Plan
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Acronyms and Abbreviations (continued)
NPL
NVP
O&M
OAR
ODEQ
ORNL
ppm
ppb
RAB
RAC
RCRA
RDX
RID
RIlFS
ROD
SARA
SDWA
SF
TBC
Ta..P
Tetryl
TNB
TNT
TRC
UMDA
USAEC
National Priorities List
Net present value
Operations and Maintenance
Oregon Administrative Rules
Oregon Department of Environmental Quality
Oak Ridge National Laboratory
PartS Per Million (equivalent to mgIL, ~g/g and mg/kg)
PartS Per Billion (equivalent to ~g/L and ~g/kg)
R :storation Advisory Board
Remedial Action Criteria
Resource Conservation and Recovery Act
Hexahydro-l,3,5-trinitrO-l,3,5-triazine (Royal Demolition Explosive)
Reference Dose
Remedial investigation and feasibility study
Record of Decision
Superfund Amendments and Reauthorization ACt of 1986
Safe drinking water
Slope Factor
To be considered
Toxicity characteristic leaching procedure
2,4,6- TettanitrO-N- Methylaniline
1,3,5- Trinitrobenzene
2.4,6- Trinitrotoluene
Technical Review Committee
U.S. Army Depot Activity at Umatilla
U.S. Army Environmental Center (fonnerly USATHAMA)
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1.0 Declaration of the Record of Decision
Site Name and Location
U.S. Army Depot Activity, Umatilla
Explosives Washout Lagoons, Ground Water Operable Unit
Hemnston, Oregon 97838-9544
Statement of Basis and Purpose
This decision document presents the selected remedial action for the Explosives
Washout Lagoons (EWL) Ground Water Operable Unit at the U.S. Anny Depot
Activity, Umatilla (UMDA), at Hermiston, Oregon. The remedial action has been
chosen in accordance with the Comprehensive Environmental Response,
Compensation, and Liability Act of 1980 (CERDA), as amended by the Superfund
Amendments and Reauthorization Act of 1986 (SARA), and, to the extent practicable,
the National Oil and Hazardous Substances pollution Contingency Plan (NCP). The
decision is based on the administrative record for this site. Documents supporting this
Record of Decision (ROD) are identified in Appendix B.
The remedy was selected by the U.S. Army and the U.S. Environmental Protection
Agency (EPA). The State of Oregon concurs with the selected remedy.
AsseSsment of the Site
ActUal or threatened releases of hazardous substances from the site, if not addressed by
implementing the response action selected in this ROD, may present an imminent and
substantial endangerment to public healt~, welfare, or the environment.
Description of the Selected Remedy
The Explosives Washout Lagoons Ground Water Operable Unit is the second of three
operable units that are to address the Explosives Washout Lagoons. The operable units
were divided by contaminated media: soils, ground water, and building and equipment.
The first operable unit addressed the Explosives Washout Lagoons Soils (ROD was
issued in September 1992). The Ground Water Operable Unit addresses contaminated
ground water caused by past waste ~ to the Explosives Washout Lagoons. The
third operable unit is specific to the reinediation of the Explosives Wash put Plant. This
operable unit includes the remediation of the con~minated building smfaces and
equipment; the explosive contam;nated soils surrounding the plant will be remediated
with the Explosives Washout Lagoon Soils.
In tOtal, eight operable units have been identified at the UMDA site:
.
Inactive Landfills
Active Landfill .
Ground Water Contamination from the Explosives Washout Lagoons
Ammunition Demolition Area (ADA)
Miscellaneous Sites
Explosive Washout Plant (Building 489)
Washout Lagoons Soils
Deactivation Furnace and Surrounding Soils
.
.
.
.
.
.
.
rctI.drri.~1IIL6I7/94
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The selected remedial action for the Explosives Washout Lagoons Ground Water
Operable Unit is Alternative 4B from the feasibility study (FS) report, extraction of the
contaminated ground water followed by granular activated carbon (GAC) treatment of
the ground water and reinfiltrarion of the ground water back into the aquifer. The major
components of the alternative are:
.
Extraction of the ground water from an estimated three extraction wells over an
estimated 10- to 30~year period
Treaunent by GAC to meet perfonnance standards based on the ground water
cleanup levels
.
.
In-situ flushing of subsurface soils beneath the lagoons with all or part of the
treated ground water for an estimated period of one year
Upgradient reinfiltration of the treated ground water that does not go to the
Explosive Washout Lagoons and all the treated water after the in-situ soil flushing
is completed
. "
.
Testing of the spent GAC to determine RCRA characteristic hazardous waste status
Off-site thermal treatment and disposal of explosive-contaminated GAC to the
level specified in the remedial design (off-site thermal treatment will be in
compliance with the NCP Off Site Rule) "
.
.
Monitoring of ground water conts:lmination to detennine the effectiveness of the
remedial action and to determine when the ground water cleanup levels have been
attained
Institutional controls on the contaminated ground water to prevent the use of the
ground water until the ground water cleanup levels are met
.
The remediation of the ground water will continue until the concentration of explosives
in the aquifer meets cleanup levels that are proteetive of human health and the
environment. Because no applicable or relevant and appropriate requirements (ARARs)
currently exist for the" explosive contaminants. risk-based cleanup levels were "
calculated to proteCt against carcinogenic risks in excess of 1 x 1~ and non-
carcinogenic risks with a hazard quotient greater than 1. Lifetime Human Health
Advisories were considered ""To Be Considered" (TBC) ARARs and were also used to
set cleanup levels. The performance standards for the treattnent of the extraCted ground
water were set in the same manner as the cleanup levels for the aquifer.
A limit of 10 percent explosives on the GAC sent off site was set in order to ensure that
~ the GAC would not be a characteristic RCRA hazardous waste for reactivity. The 10
percent limit was set based on a USAEC study (Arthur D. Little. 1987) to determine"
reactivity of explosive-contaminated sludges. The spent GAC would also have to pass a
tOxicity characteristic leaching procedure (TCLP) test for 2.4-DNT in order not to be
considered a RCRA hazardous waste. The performance standards for the off-site
thermal treatment of the explosive-contaminated GAC would be determined during the
remedial design; however they would be based on either a residence time and
temperature or a chemical-specific cleanup level for the residuals that are below risk-
" based remedial action criteria.
r=-clrrI.aja.67Q62062.IpL&'7194
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In order to ensure that the off-site thennal treatment does not contribute to present or
future environmental problems. the selection of a thermal treattnent facility will follow
the procedures presented in Procedures for Planning and Implementing Off-Site
Response Actions, FR 49200 September 22, 1993.
The goal of this remedial action is to restore the ground water to its beneficial use,
which may include drinking water or non-domestic uses. Based on the information
obtained during the remedial investigation (RI) and the analysis of all remedial
alternatives, the Army, EP A, and the State of Oregon believe that the selected remedy
may be able to achieve this goal. Ground water contamination may be especially
persistent in the immediate vicinity of the contaminants' source, where the
concentrations are relatively high. The ability to achieve cleanup levels at all points
throughout the area of attainment, or plume, cannot be determined until the extraction
system has been implemented, modified as necessary, and plume response monitored
over time.
The selected re."edy will inClude ground water extraction for an estimated period of 10
to 30 years, during which time the system's perfonnance will be carefully monitored on
a regular basis and adjusted as warranted by the perlormance data collected during
operation. Modifications may include any or all of the ~ollowing:
.
Discontinuing pumping individual wells where cleanup levels have been attained
Alternating pumping at wells to eliminate stagnation points
.
.
Pulse pumping to allow aquifer equilibration and encourage adsorbed contaminants
to partition intO the ground water
Installation of additional extraetion wells to facilitate or accelerate cleanup of the
contaminant plume
.
To ensure that cleanup levels continue to be maintained, the aquifer will be monitored
at least annually at those wells where pumping has ceased. When the ground water
cleanup levels have been achieved at all the extraetion wells and have not been
exceeded fot a period of three consecutive years, the cleanup will be considered
complete. . .
Statutory Determinations
The selected remedy is protective of human health and the environment, complies with
federal and 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 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 above
cleanup levels for a period greater than five years after the commencement of the
remedial action, reviews will be conducted at five-year intervals to ensure the remedy
continues to provide adequate protection of human health and the environment. The
first five-year review will include consideration of the following elements: .
rtb.dn'f..llja.67062-Q.IpLfflllM
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.
The perfonnance of the ground water treatment system in achieving cleanup levels
.
The Hazard Quotient for 1.3,5-trinitrobenzene (TNB), as recalculated following
chemical-specific toxicity studies initiated by the U.S. Anny
Propeny use above the ground water plume to ensure that water with contamination
. above cleanup levels is not used
.
tdI.dmI.aja.~194
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Lead and Support Agency Acceptance 01 the Record of Decision
U.s. Army Depot Activity UmatUla
Explosives Washout Lagoons, Ground Water Operable Unit
SignatUre sheet for the foregoing Record of Decision for the Explosives Washout
Lagoons Ground Water Operable Unit final action at the U.S. Anny Depot Activity at
Umatilla betWeen the U.S. Army and the United States Environmental Protection
Agency. with concurrence by the State of Oregon Depanment of Environmental
Quali ty.
~t.,(p~
wis D. Walker
Deputy Assistant Secretary of the Anny
(Environment. Safety. and Occupational Health)
;/30/71
Date
..-~..
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Lead and Support Agency Acceptance of the Record of Decision
. . U.S. Army Depot Activity Umatilla .
explosives Washout Lago,ons, Ground Water Operable Unit (continued)
Signature sheet for the foregoing Record of Decision for the Explosives Washout
L,agoons Ground Water Operable Unit final action at the U.S. Army Depot Activity at
Umatilla between the U.S. Army and the United States Environmental Protection
Agency. with concurrence by the State of Oregon Department of Environmental
Quality .
~~
Lieutenant Colonel Moses Whiteti st. Jr.
Commander. U.S. Army Depot Activity. Umatilla
~~9'4
~IIN
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Lead and Support Agency Acceptance of the Record of Decision
U.S. Anny Depot Activity Umatilla .
Explosives Washout Lagoons, Ground Water Operable Unit (continued)
Signature sheet for the foregoing Record of Decision for the Explosives Washout Lagoons
Ground Water Operable Unit final action at the U.S. Army.Depot Activity at Umatilla
between the U.S. Army and the United States Environmental Protection Agency, with
concurrence by the State of Oregon Department of Environmental Quality.
. . .
~
Date
n:b.dmf .8j8.1570152oC12.rpt.71181"
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Lead and support .Agency Acceptance of the Record of DeCIsion
US. Army Depot ActIVity umatlUa . .
explosives Washout Lagoons, Ground Water Operable Unit (continued)
Signawn:: sheet for me foregoinC Rccmd of])ecision for the Explosives Washout
Lagoons Ground Water Operable Unit IiDa1 aaion at me U.S. Arrrs'I Depot Aetivity at
Umatilla betWeen the U.S. Army and the United StateS Environmental Protection'
AlCncy, with concurrence by the State.of Oregon Department of EnviIomnental
Quality. .
~~
Chuck a~
Regional AdminiStrat01'. Region X
U.S. En~~enw Protection Agency
Date
~
1
"
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Lead and Support Agency AccepUU1ce of the Record of Decision
. U.s. Army Depot ACtivity Umatilia
explosives Washout u.goons, Ground Water Operable Unit (continued)
Signamre sheet for the foregoing ReCom of Decision for the Explosives Washout
Lagoons Ground Water OpCr2ble Unit final aCtion at the U.S. Army Depot Aetmty at
Umari11a. betWeen the U.S. Army and the United SmJcs Environmental Prorecaon
Agency, with conCUIICnce by the Swe of Oregon Depanment of Environmenw.
QoaJity.
~~~
Fred Hansen
Di1~tOt . .
Qxegon DepanmeDt of EnvironmenW Quality
(JUL 2 6 1994
Date
Nare:
'1be SIaC of On:pI's law of Cora. w....-'C is appciuscd to dIis Reccx'd of Decision in
AppeDdiX A. .
~,,"-.
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2.0 Decision Summary
This Decision Summary provides an overview of the problems posed by the ground
water conditions at the UMDA Explosives Washout Lagoons (EWL), the remedial
. alternatives, and the analysis of those options. Following that, it explains the rationale
for the remedy selection and describes how the selected remedy satisfies statUtory
requirements.
2.1 Site Name, Location, and Description
The U.S. Army Depot Activity at Umatilla (UMDA) was established as an Army
ordnance depot in 1941 for the purpose of stOring and handling munitions. Access is
currently restricted to installation personnel. authorized contractors. and visitors.
UMDA was included in the Department of Defense (DoD) Base Realignment and
Closure (BRAC) program. which requires that the UMDA conventional ordnance
storage mission be transferred to another installation. Under this program, it is probable
that the Army will eventUally vacate the site; ownership could then be relinquished to
another governmental agency or private interests. Light industry is considered to be the
most likely future lard use scenario for UMDA; furore residential use is also a
possibility .
UMDA is located in northeastern Oregon in Monow and Umatilla Counties.
approximately 5 miles west of Hermiston, Oregon. as shown in Figure 1. The
installation covers 19.729 acres of land. of which 17.054 are owned by the Army and
. the remaining 2,675 acres are limited to agricultural use by resttictive easement.
Contamination of the ground water occurred in the vicinity of the UMDA Explosives
Washout Lagoons. as shown in Figure 2. .
The Explosives Washout Lagoons site. also called Site 4. consists of tWO adjacent,
unlined lagoons. each approximately 25 feet by 70 feet and 6 feet deep. Wastewater
was discharged from the Explosive Washout Plant to the lagoons via a sheet metal
trough. This trough has a concrete sump located about halfway betWeen the Washout
Plant and the lagoons.
During the washout operations. the sump collected sludge solids as excess washout
water flowed through the trough to the lagoons. The tWO lagoons were used alternately.
to allow the wastewater time to inflltrate into the soils. Sludge residue from the sump
and the lagoon bottoms was collected. allowed to dry. and burned at the Ammunition
Demolition Area (ADA) at UMDA.
The wastewater from the washout operation. also known as "pink water.:' contained
high concentrations of explosives. An estimated 85 million gallons of this wastewater.
were discharged into the lagoons during their operation. The lagoons are located in a .
gravelly. sandy area, are unlined, and were intended to permit infiltration and
evaporation of this wastewater.. The wastewater. seeped from the lagoons and
contaminated the .shallow ground water beneath the lagoons.
Ground water. occurs beneath UMDA in a number. of distinct hydrogeologic settings, in
a series of relatively deep confined basalt aquifers and in a highly productive permeable
unconfined aquifer in the south ofUMDA (extending off-post). However. the ground
water. that has been contaminated by the use of the Explosives Washout Lagoons is
isolated to the unconfined aquifer. .
rd:).clm.$.671)62062.111L6f711M
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,.. . Sunnyside ~ \~ :.. ..t] :,
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, Benton County ...' ~ . '. Walla Walla \
---,-,-,-,-,-,-,-,-1 .t.~"'-"''-- WASHINGTON
. / ..--..~._--_.--.~..--..--.r.--.--..-
\ I .~, (,OREGON
- . ,'~,,~.~~' ~~ \'.~II'W",RJv"/ I
GO 4V:' r Urnat"'a ...........,.../ I
Klicldlal County . ~I .,.' ,
, - ~~, rr go , /.") .
~- e:ardman ' '.Hermlston .J
/~'~1. I I "'\"1. U...".Coun~ IJ
~~ ',I UMDA Site ',I ,.~'/. ~...-..,-
r', l '.-..' Pendleton
i \ Morrow County \ .-.,
I' \ ,-...t'~~.,
. .~~~
,. '.-",;,\ ., -7
I "~ '
i :. .~~ i !
i \.\ '-..., \ \'"
. \-& ' . '\ .;
I ..~_.,,' 1 /.
" ", ,...'
Gilliam County
t
1
i
...
N
o
10
Scale In Mias
20
Source: Arthur D, Little, Inc" 1993, Fig t
..£
o
Figure 1 .
Facility Location Map
-------
t
UMATILLA
ORDNAN
DEPOT
SCAL£
o
500FT
.~
8
SCALE
r- -.
- - FT
[
--
All:
ROO on UMA1IL1A Lagoons Ground Water
IIIIIr:
.wi. 1994
mu: .
AS SHOWN
IllIG. lID.:
67062-G44
FlgU1'8 2: Location 01 ExpIo8lv88 W88hoU1 Plant
.. and WashoUt We- Sump
rdI.«*III.67'D62~415194
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Northeastern Oregon, the setting for UMDA, is characterized by a semi-arid, cold
desen climate, an average annual precipitation of 8 to 9 inches, and a potential annual
evapo-ttanspiration rate of 32 inches. The installation is located on a regional plateau of
low relief that consists of relatively permeable glaciofluvial sand and gravel overlying
Columbia River Basalt.
The region surrounding UMDA is primarily used for irrigated agriculture. The .
population centers closest to UMDA are Henniston (population 10,075), approximately
5 miles east; Umatilla (population 3,032), approximately 3 miles nonheast; and Irrigon
(population 820), 2 miles northwest. The total populations of Umatilla and Morrow
Counties are approximately 59,000 and 7,650, respectively.
Approximately 1,470 wells have been identified within a 4-mile radius of UMDA, the
majority of which are used for domestic and irrigation water. Three municipal water'.
systemS (Hermiston, Umatilla, and IIrigon) draw from ground water within a 4-mile
radius of UMDA. The Columbia. River is a major somce of potable and irrigatior
water, and is a' -~ used for recreation, fishing, and the generation of hydroel..ctric
power: The principal use of the Umatilla River is inigation.
2.2 Site History and Enforcement Activities
From the 19505 until 1965, UMDA operated an on-site explosives washout plant
similar to that at other Army installations. The plant processed munitions to remove and.
recover explosives using a pressurized hot . water system. The principal explosives
consisted of the following:
.
2,4,6-trinitrotoluene (TNT)
Hexahydro-l,3,5-trinitro-l,3,5-triazine (Royal Demolition Explosive or RDX)
Octahydro-l,3,5,7-tettanitro-l,3,5,7-tetIaZOcine (High Melting Explosive or HMX)
2,4,6-tetranitro-N -methylaniline (retryl)
.
.
.
In addition, the munitions contained small quantities of 2,4-dinitrotoluene (2,4-DNT);
2,6-dinitrotoluene (2,6-DNT); 1,3,5-trinitrobenzene (TNB); 1,3-dinitrobenzene (DNB);
and nitrobenzene (NB) occmring as either impurities or degradation products of TNT. .
Operation of the plant included flushing and draining the explosives washout system.
The washwater produced was discharged via an open metal trough to the two
infiltration lagoons located to the northwest of the plant. The lagoons were constructed
in the 19505 and used until 1965, when plant operations and all discharges to the
lagoons ended. A total of 85 million gallons of effluent is estimated to have been
discharged to the lagoons during the period of plant operation.
An initial installation assessment was performed in 1978 and 1979 to evaluate
environmental quality at UMDA With regard to the past use, storage, treatment, and
disposal of toxic and hazardous materials. Based on aerial imagery analysis provided by
EPA's Environmental Photographic Interpretation Center (EPIC) as part of the
assessment, the Explosives Washout Lagoons (Site 4) were characterized as a
potentially hazardous site. In 1981, Battelle conducted an Environmental
Contamination Survey and Assessment at UMDA and identified what appeared to be a
45-acre plume of RDX in the shallow aquifer underneath the Explosives Washout
Lagoons. Battelle concluded that discharges to the lagoons had caused contamination. of
rc:b.drrlAja.6?062-62.rpL6I711M
-------
the alluvial aquifer. Subsequent investigations confinned the presence of explosives in
the soil and ground water.
In 1984, the Explosives Washout Lagoons were evaluated using EPA's Hazard
Ranking System (HRS) and received a score above 28.5. As a result, the lagoons were
proposed for inclusion on the National Priorities List (NPL) in 49 Fed. Reg. 40320
(October 15, 1984). They were formally listed on the NPL in 49 Fed. Reg. 27620 (July
22, 1987) based on the HRS score and the results of the installation RCRA Facility
Assessment.
On October 31, 1989, a Federal Facility Agreement (FFA) was executed by UMDA,
the Army, EP A Region X, and the Oregon Department of Environmental Quality
(ODEQ). The FFA identifies the Army as the _ead agency for initiating response
actions at UMDA. One of the purposes of the FFA was to establish a framework for
developing and implementing appropriate response actions at UMDA in accordance
with CERa..A, the ~CP, and Superfund guidance and policy. Investigation and
remediation Ct. contaminated soil and ground water at the lagoons was a task identified
within this framework. A remedial investigation and feasibility study (RIIFS) of the
entire UMDA installation, including the lagoons, was initiated in 1990 to detennine the
nature and extent of contamination and to identify alternatives available to clean up the
facility.
The RI and the human health baseline risk assessment (HBRA) were completed in
August 1992. For pmposes of the Feasibility Study, the washout lagoons soils and
washout lagoons ground water were each designated as separate operable units. The
Army, EPA, and ODEQ concurred on a ROD for the Washout Lagoons Soils Operable
Unit in September 1992, which specified excavation and composting of all soils with
TNT and RDX greater than 30 mg/kg. The feasibility Study for the washout lagoons
ground water was completed in December 1993, and the proposed plan was made
available to the public in February 1994.
2.3 Highlights of Community Participation
. In 1988, UMDA assembled a Technical'Review Committee (TRC) composed of
elected ~d appointed officials and other interested citizens from the surrounding
communities. Quarterly meetings provided an oppornmity for UMDA to brief the TRC
on installation environmental restoration projects and to solicit input from the TRC.
Two TRC meetings were held during preparation of the feasibility study for the
Explosives Washout Lagoons Ground Water Operabl~ UniL In those meetings, the
TRC was informed as to the scope and methodology of the. ground water investigation.
and remediation. . ..
In December 1993, the TRC was expanded to meet the requirements of the Restoration
Advisory Board (RAB) based on DaD guidance. Two RAB meetings were held during
the selection of the proposed alternative. .
The feasibility study and proposed plan for the Explosives Washout Lagoons Ground
Water Operable Unit were made available to the public on February 15, 1994, at the
following information repository locations: UMDA Building 32, Hermiston, Oregon;
the Hermiston Public Library, Henniston, Oregon; and the EP A offices in Ponland,
Oregon. The notice of availability of the proposed plan was published in the Hermisron
rdl.dm~.94
-------
Herald, the Tri-Ciry Herald, and the Ease Oregonian on February 15, 1994. The public
comment period began on February 15, 1994, and ended on March 17, 1994.
A public meeting was held at the Armand Larive Junior High School, Henniston,
Oregon, on March 2, 1994, to infonn the public of the preferred alternative and to seek
public comments. At this meeting, representatives from UMDA, the U.S. Army
Environmental Center (USAEC), EPA, ODEQ, and Arthur D. Little, Inc. (an
environmental consultant) answered questions about the site and remedial alternatives
under consideration.. A response to comments received at the meeting and during the
3O-day comment pe~od is included in Section 3.0, Responsiveness Summary.
2.4 Scope and Role of Operable Unit
Operable units are discrete actions that constitute incremental steps toward a final
overall remedy. An operable unit can be an action that completely addresses a
geographic portion of a site or a specific problem, or it can be one of many ~t:ri, m~ that
will be taken at the site.
The Explosives Washout Lagoons Ground Water Operable Unit is the second of three
operable units that are planned for the Explosives Washout Lagoons area. The operable
units were divided by contaminated media: soils, ground water, and building and
equipmenL The first operable unit addressed the Explosives Washout Lagoons Soils
(ROD was issued in September 1992). The Ground Water Operable Unit involves
remediation of contaminated ground water beneath the lagoons. The third operable unit
is specific to the remediation of the Exr\osives Washout PlanL This operable unit
includes the remediation of the contaDhUated building surfaces and equipment; the
explosive contaminated soils surrounding the plant will be remediated with the
Explosives Washout Lagoons Soils.
In total, eight operable units have been identified at the UMDA site:
.
Inactive Landfills
Active Landfill .
Ground Water Contamination from the Explosives Washout Lagoons
Ammunition Deinolition Area (ADA)
Miscellaneous SiteS
Explosive Washout Plant (Building 489)
Washout Lagoon Soils
Deactivation Fmnace and Surrounding Soils
.
.
.
.
.
.
.
2.5 Site Characteristics and environmental Investigation Results
. Ground water occms beneath UMDA in a number of distinct hydrogeologic settings
(Figure 3), in a series of relatively deep confined basalt aquifers and in a highly
productive permeable unconfined aquifer in the south ofUMDA (extending off-post).
However, the ground water that has been contaminated by the use of the Explosives
Washout Lagoons is isolated to the unconfined aquifer.
. niI.cInf~~6I7.94
-------
Figure 3: Stratigraphic Cross-Section Beneath UMDA Washout Lagoons
&
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.. - } ~NcoNrlNro AOUIHR
7} ELEPHANT MOUNTAIN
MEMBER
RATTLESNAkE RIDGE.
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WEST
WELL
4-19
WELL
4-20
WELL
4-21
100
800
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.00
100
100
.00
1000
100
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_."'Alr _ZONfAi. DlSIANCr (nrl'
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=r SELAH INTERBED
,'.., STRATIGRAPHIC CROSS-SECTION
BENEATH UMDA WASHOUT LAGOONS
""'0 JOlt
UMA TlllA
"""
.... NO
NOV. 1993
67062-031
EXPLANATION
D
mnrn
~
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~
ALLUVIUM
SILT AND CLAY
FLOW TOP
BASAL T
INTERBED
SOURCE: DAMES a. MOORE
lOCUS ....,.
ICOI(,
AS SHOWN
-"(10""')
M5.~
III"FfM:MD " I"I\II.S)
-------
The unconfmed aquifer at UMDA consists of the alluvial deposits and the weathered
surface of the Elephant Mountain Member basalt and is overlain by approximately 20
to 125 feet of unsaturated alluvial sand and gravel. At the Explosives Washout
Lagoons, the saturated thickness of the entire unconfined aquifer ranges from
approximately 15 to 35 feet. This estimate includes only the saturated thickness of the .
alluvium exclusive of the Elephant Mountain Member. However, water levels in wells
installed in the weathered and fractured surface of the Elephant Mountain Member have
similar elevations to wells screened in the alluvium, indicating that the flowtop is in
direct hydraulic connection with, and is therefore part of, the unconfmed aquifer. The
exact thickness of the flowtop that is in connection with the unconfined aquifer is
unknown and likely varies across the site dependent upon the thickness of the lacustrine
depQsitS and the degree of weathering.
Ground water flow directions in the unconfined aquifer near the lagoons reverse
seasonally in response to off-post irrigation pumping and recharge activities. During the
summer and ear1y fali, t10w is toward the east and south as irrigation activities peak.
During the winter and early spring, when irrigation activities are at a minimum, grou1"d
water flow is to the north and west It is probable that, prior to initiation of irri~cition in
the 1950$ and 1960s, the natural.direction of flow in the aquifer was to the northwest
toward the Columbia'River and, in the direct vicinity of the Umatilla River, possibly to
the northeast Currently, because water level declines have occurred in the aquifer,
discharge is probably exclusively to inigation wells. There is likely insufficient head
now to cbive ground water either into the finer sediments of the northern aquifer or over
the top of the finer sediments within the more permeable sediments (which"are now
dewatered and overlie the finer northern aquifer se.rlimP.Qts).
In 1992, an RI of the ground water at tt. . Explosives Washout Lagoons was completed
to determine the extent of explosive contamination so that appropriate plans for
remediation (cleanup) could be developed. A summary of the contamination in the
unconfined aquifer during the RI and Phase n RI program (November 1990 to
December 1992) is presented in Table 1 along with comparison criteria. The
comparison criteria were developed based on ARARs (e.g., maximum contaminant
levels [MCLs], Health Advisories) or risk-based levels that provide a carcinogenic
"protection of lx1()-6 or a non-carcinogenic hazard quotient of 1. These levels were then
compared to background levels and deteC!ion limits. Where the background level or the
detection limit was higher than the ARAR or risk-based level, the comparison criteria
was set at the background level or the detection limit
Ground water Samples were collected and analyzed during the RI from 30 wells in the
upper sandy portion of the unconfined aquifer. The deeper poJrion of the unconfined
aquifer is primarily silty sand and is discussed below. Contamination of explosive
compounds was deteeted in ground water from 18 of the 30 wells. The most common
contaminant was RDX, with concentrations ranging from below deteCtion Oess than
0.556 J..lg/L) to 6,816 J..lg/L (MW-28, February 14, 1991). RDX was deteeted above its
comparison criteria (2.1 J..lg/L) in 16 of the locations and above 1,000 J..lg/L in four of
the locations. RDX, the most mobile of the contaminants, has the largest plume
(Figure 4). From the lagoon source area, the RDX plume extends primarily to the
southeast with some elevated concentrations to the northwest The plume is well
delineated to the northeast and southwest where steep chemical concentration gradients
are present It appears that me irrigation-induced ground water flow direction (to the
southeast) has a greater effect on contaminant migration than does the natural flow
rc:D.dml.aja.67062.Q.rpI.&'7'"
-------
Table 1: Summary of Contaminants of Concern in the Ground Water at
the Explosives Washout Lagoons
Explosives
TNB
ONB
NB
TNT
2.4 - DNT
2,6 - DNT
HMX
ROX
T etryl
Nitrate
Average
ij!g/L)
119
7.6
14
1,557
255
5.3
383
992
0.8
13,~30
Minimum
(J.1.g/L)
0.8
0.6
13
0.8
0.8
5..3
1.9
2.7
0.8
15
Maximum
(J1g/L)
441
24.4
16
3,900
497
5.3
1,448
6.816
0.8
48,000
Notes:
Average is equal to the average of all detected concentrations.
MinirTalm is equal to the minimum deteCted value.
Source: Dames & Moore. 1992b
~mparisOn Criteria
Concentration Type
(J.1.g/L)
1.8
4.0
20
2.8
0.6
1.2
350
2.1
400
54.000
Risk-Based.
Risk-Based
Risk-Based
Risk-Based
Detection Umit
Detection Umit
Health AlJvisory.
Detection Umit
Risk-Basr-1
Background
rdI.dn'IAja.67062-62JP.617094
-------
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-, ~.... Wode&ed Conc:entrotion Contour in ~b
DWG. NO.:
67062-020
DATE:
NOV. 1993
SCALE:
200--
'l:~. of wonitari"9 Well Actual Concentrations
I
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1000 FT
~
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PIT
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TITLE:
Agure 4
SIMULATED AND OBSERVED RDX GROUN
-------
direction (to the nonhwest). The RDX plume represents the extent of migration. of the
contaminants. Based on that plume the estimated volume of contaminated ground water
is 830 million gallons.
Other explosives compounds deteCted above their comparison criteria include TNB,
DNB, HMX, TNT, 2,4-DNT, and 2,6-DNT. Compounds deteetOO below their
comparison criteria include tetryl and NB. The other explosives compounds are less
mobile than RDX and therefore have more locaJi7ed plumes. A concentration contour
map for TNT is provided in Figure 5 as an example of the less mobile conwninant
plumes. .
Eleven wells in the upper sandy portion of the alluvial aquifer were sampled for
inorganics. Of those wells sampled. all analyses showed that metals were below
. comparison criteria of either MCLs, EPA Health Advisories, risk-based criteria, or .
background concentrations. Nittatelnitrite was found in every ground water sample and
the highest concentrations were found in the unconfined aquifer. The nittatelnitrite
concentration in this aquifer ranged from approximately 10,000 J.1.g/L to 40,000 ~.
While these concentrations exceeded the Safe Drinking Water Act Ma.. of 10,000
~,they were below the background nitrate con~entrations found in off-site wells
smrounding the UMDA property. The ground water sunounding UMDA has high
levels of nitrates because of the use of fertilizers for agriculture. Due to the high level
of nitrates in the surrounding areas, nitrates were not considered a contaminant of
concern for the ground water at the Explosives Washout Lagoons.
Of the four wells in the lower silty sand portion of the alluvial aquifer. three had
deteetable explosives compounds. No explosives were deteCted in Well 4-15 and no
explosives were detected above theircompariwn criteria in Well 4-12. Well 4-14,
located northweSt of the source, had RDX slightly above its comparison criterion. Well
4-13, southeast of the source, had both RDX and 2,4-DNT at about their comparison.
criteria. The highest concentration of explosives in this layer, 2,400 J.lg/L of RDX, was
deteeted in Well 4-13.
Three wells are installed in the weathered portion of the Elephant Mountain Member.
Two (S8-1 and SB-3) contain RDX slightly above the comparison criterion. The
highest RDX Con~ntration in this geologic structure was found at SB-2 (76 J.lgIL), but
the concentration was unconfumed and not found in later rounds of sampling.
- Four intermediate wells were installed below the Elephant Mountain Member to
determine whether the Rattlesnake Ridge Interbed had been contamin~t~ The results
of the tWo rounds of sampling showed that all conhminants of concern were below
detection limits. Based on the results of this sampling round the Army determined that
me Rattlesnake Ridge Intcrbed was not conmmin~tM and, therefore, did not require
remediation. Four wells were also installed into the second basalt aquifer (Selah
Interbed). Sampling of these wells found explosives connmination in tWo of the wells.
Because migration of conhminants from the unconfined aquifer to the second basalt
aquifer would cause CODhmination of the uppermost basalt aquifer, and this was not
found, well leakage was identified as the cause of the deep aquifer con.,.min~rion.
Additional sampling of the second basalt aquifer wells and use of a video camera to
inspect the wells casings confirmed that a low rate of leakage was the cause of the
coDuminarion. The leakage of connminsted ground water to the second basalt aquifer
will be addressed by removing the two leaking wells.
nD#I'I.aja.67'062Q.1pL61H4
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DWG. NO.:
67062-021
DATE:
DEC 1993
SCALE:
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Figure 5:
4':"24
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SIMULATED AND OBSERVED TNT GROUNC
-------
Physical and chemical properties of the explosives are provided in Table 2. In general,
the explosives can be characterized as having relatively low aqueous solubility and low
volatility. Health effects criteria for the explosives, including carcinogenic data from
EP A databases, are presented in Section 2.6.
The major potential route for migration of the explosive contamination is through the
subsurface spread of contamination. However, the rate of traDspon is uncertain due to.
the seasonal change in the ground water flow direction. Modeling during the FS found
that the contamination would reach the south UMDA boundary in approximately 70
years. The modeling also estimated that the contamination would theoretically persist in
the aquifer at levels above those protective of human health for 5,000 years.
2.6 SUmmary of Site Risks
This section summarizes the human .health risks and environmental impacts associated
with exposure to site contaminants and provides potential remedial action criteria.
2.6.1 . Human Health Risks
A Human Health Baseline Risk Assessment (HBRA) was conducted by the Army to
estimate the risk posed to human health by the cont~min~ted ground water at the
Explosives Washout Lagoons should it remain at its current state with no remediation.
The risk ~sessment consisted of a toxicity assessment, exposure assessment, and
human health risk characterization. The toxicity assessment documented the adverse
effects that can be caused in a receptor as a result of exposure to a site cOn~minanL .
The exposure assessment detailed the exposure pathways (such as ingestion) that exist
at the site for various receptorS. The risk characterization used both the exposme
concentrations and the toxicity data to detennine a Hazard Index (HI) for potential non-
carcinogenic effects and a cancer risk level for potential carcinogenic contaminants.
The contaminated shallow ground water is currently not used because it is contained
within the boundaries ofUMDA and UMDA potable water is from deep basalt wells;
however. the shallow aquifer is used for both agriculture and domestic use in the area
surrounding .UMDA. Based on the current use of the aquifer there is no current risk
from the ground water contamination, but the future use of the aquifer could potentially
be agricuItoral and domestic. Because of the potential for agricultural and dpmestic
usage of the ground water, the HBRA is based on a residential exposure scenario.
. .
Contaminants of concern in the Explosives Washout Lagoons Ground Water Operable.
Unit were identified as those explosives detected in water samples collected during the
R1. They were: .. .
. TNB
. DNB
. NB
. TNI'
. 2,4-DNT
. 2.6-DNT
. RDX
. HMX
. Terryl
tdI.drrI~
-------
Table 2: Physical and Chemical Properties of. the Explosives In Washout Lagoon Ground Water
TNT 1.4-0NT I."ONT TNe ONe ADX HMX Totryl
CAS Regletry No. 118....7 111.14.2 8C)8.20-2 ...11-4 ".S5.0 121.82.4 28D'.4'.0 47D.45.8
Empl~C81 Formula C7H6N30S C7HsN204 C7HsN204 CeH3N30s CSH4N204 C3HSNS08 C4H8N808 C1HSN508
Molecul., Weight 227. t5 IS2.15 IS2.15 213.12 188.12 222.16 20820 281.11
OeneUy (glcm3) 1.88 1.821 1.838 1.83 1.876 1.83 LOO (B lorm) U3
"'elling Polnl ('C) 80.78 72 88 122 110 205 288 120S
Vepor Preeeure (mm Hg, 2S'C). 6.611110.S 2.171110.4 11.871110'. 1.0I1I10'S 1.311110.4 4.031110.g 3.33.,0.,4 5.69.10.9
Aqueou. Solubility (mg/L, 26'C) 1&0 280 208 381 633 80 6 80
.Henry'. Con.tanl (atm.m3/mole, latC) 1.101110.8 1.881110.7 4.881110.7 UIII10" 6.441110.8 1.081110'" 2.80.10.15 2.69.,0.11
Log !
-------
Concentrations for the contaminants of concern are presented in Table 1.
2.6.1.1 Toxicity Assessment. Toxicological profiles were developed for the HBRA
and are included in Appendix D of that document. A summary is provided in
Table 3. Information on the profiles includes. where available: non-carcinogenic
effects and reference doses for oral ingestion and inhalation; carcinogenic effects, slope
factors and weightS-of-evidence for oral ingestion, dermal absorption, and inhalation;
and references.
Reference dose (RID:' values are used to evaluate non-carcinogenic effects. RIDs are
derived from "no-observed-adverse-effect levels" (NOAELs), which represent the
highest experimental exposure level at which a particular critical toxic effect is not
observed. Cancer slope factorS (SFs) are used to evaluate potential human carcinogenic
risks. A SF is .defined as an estimate of the upper 95 percent confidence limit of the
slope of the dose-response curve extrapolated to low doses, and is considered to.be a
measure of the cancer-causing potential of a chemical. RIDs and SFs are provided for
both ingestion and iT'halation. Toxicity values are obtained from the Integr:"~ klsk
Information S) stem (IRIS). the Health EffectS Assessment Summary Tables (HEAST),
EPA Region ill Toxicity criteria. the Public Health Risk Evaluation Database. the
Drinking Water Criteria documentS, the Ambient Water Quality Criteria documents, the
Air Quality Criteria documents. and the Agency for Toxic Substances and Disease
Registry (A TSDR) toxicity profiles.
Because of the paucity of toxicity data for TNB. EPA derived an RID by analogy to
DNB. This analogy is considered appropriate and acceptable because of their strUcmral
similarity and the fact that TNB is less tOxic on an acute basis than DNB. To account
for the derivation by analogy, the RID for TNB incorporateS an additional uncertainty
factor of 10. The Army has initiated TNB-specific tOxicity studies designed to reduce
this uncertainty and provide a more definitive estimate of the RID.
2.6.1.2 Expnsure AsseSsment. Exposure scenarios include a contaminant source, a
release or transpon mechanism. an exposure pathway by which the contaminant enters
the receptor's body. and a potential receptor. The pathways included for quantification
of the risk for ground water at the Explosives .Washout Lagoons are sUJDIDarized below:
.
Ingestion of contaminated ground water
Dermal absorption of CODV'mjn~ted ground water during showering
Consumption of crops irrigated with contaminated ground water .
.
.
For each of the three pathways. an average daily intake was calculated using a variety
of assumptions. i.e. receptOr body weight. frequency of exposure. exposure duration.
respiration rateS. absorption factors. skin smface areas. and ingestion rateS. Tables 4
through 6 present the quantitative summary of the daily intake for each pathway. For
; details regarding which parameterS are included in the individual pathways. refer to the
HBRA (Dames & Moore. 1992b). . . . .
For pmposes of calculating daily intake. TNT. RDX. HMX. TNB. and 2.4-DNT ground
water concentrations were conservatively assumed to be the maximum concentrations
observed during the remedial investigation. Ground water concentrations of the other
explosives of concern were assumed to be the 95 percent upper confidence limit on the
arithmetic mean of sampling data. Using these concentrations and exposure factors
~1.M
-------
Table 3:. Summary of Toxicity Criteria for the Contemlnants 01 Concern In Washout Lagoons Ground Water
5.00E-05
~lIlIlrl.
low
Increased 10,000
splenic weight
Increased 3,000
splenic weight
Liver effects 1,000
low
1,3,5-
Trlnltrobenzene
1,3-
Dlnltrobenzene
2,4,. 0.030 IRIS C
Trinitrotoluene
2,4- 0.880 HEAST B2
Dlnhrotoluene
2,8- 0.880 HEAST B2
Dlnltrotoluene
IRIS
1.00E-04
IRIS
urinary bladder 5.00E-04
papillomas
IRIS
medium
liver, mammary 8.00E-04
gland
USEPA, Hepatic
1991c alterations
1,000
low
(a)
1.00E.Q3
USEPA,
1991c
Liver, kidney,
neurological,
reproductive
and hematolo-
gical effects
3,000
low
HMX 5.00E-02 IRIS Hepatic lesions 1,000 low
RDX 0.110 HEAST C hepatocellular 3.00E.Q3 IRIS Inflammation 100 high
carcinomas of prostate
and ademoma
t
j.
i
,
Sources:
IRIS:
HEAST: .
EPA, 1991c:
Integrated Risk Information System, January 1991
Health Eftectl Ai....ment SUmmary Tablel, 4th Quaner, September 1990
Risk Alleument Guidance for Superfund, Volume 1: Human Health Evaluation Manual, Supplemental Guidance, Standard
Default Exposure Factors .
(a) Baled on potential carcinogenicity of 2,4-DNT
~
-------
Table 4: Quantitative Summary of D~ily Intake for Ground Water Ingestion
Ingestion of contaminated drinking water.
95 percent upper confidence limit on the arithmetic mean chemical concentration.
..-
Intake in (mgAqJ-day)
CW - Exposure pOint chemical concentration in water (mgJl)
IR - Ingestion rate (lIday) - -
EF - Exposure frequency (dayslyear)
ED - Exposure duration (years)
BW - Body weight (kg)
AT .. Averaging time (days)
Intake - CC x IR x EF x ED
BW x AT
.:~;I!_i.I~~::~~ji~j[rlli!~j~[@11
~~~II~lIi;B.li[![[1:[[t~:;!:[:::;_::::::;:::~[!::!:;1::::::::!::!:::~[~1::::[:::;~~!::~ll~f:fii[:lli!*fu;;::~:::[:!:j::::~~~:::[:;j~[:[:!!::::::!:j:::::::::::~
Miitary
IR
EF
ED
BW
AT
- 21!day (USEPA. 1991b)
- 350 daysIyr (USEPA, 1991b)
- 30 years (USEPA. 1991b)
-70 kg (adult; USEPA, 1991b)
- 70 years ]I 365 daysJyr - 25.550 days for carcinogens (USEPA. 1991 b)
- 30 years]l 365dayS1yr - 10.950 days for noncarcinogens (USEPA, 1991b)
-111day (USEPA. 1991b)
- 250 dayslyr (USEPA. ; 991 b)
- 25 years (USEPA. 199~b)
-70 kg (aduII; USEPA. 1991 b)
- 70 years x 365 daySIyr - 25,550 days for carcinogens (USEPA. 1991 b)
- 25 years x 365 daysJyr - 10,950 days for noncarcinogens (USEPA, 1991b)
- 111day (USEPA. 1991b)
- 250daysIyr (USEPA. 1991b)
- 3 years (estimated duration of fOUr of duty)
-75 kg (USEPA. 1989a)
- 70 years x 365 daysJyr - 25.550 days for carcinogens (USEPA. 1991 b)
- 3 years x 365 days/'p - 1.095 days for noncarcinogens (USEPA, 1991b)
Residential:
IR
EF
ED
BW
AT
Ught Industrial:
IR
EF
ED
BW
AT
Residential
Intake - CW (maJI\ x 2lVdav\]I gSO (MvMrear\ ]I 30 (waars\
70 (kg) ]I 25.550 (or 10.95O(days) -
- CW (mgn) ]I 1.17E.Q2 (I-kgIday) (caR;inogens)
- CW (mgn) ]I 2.74E.02 (1-kgIday) (noncarcinogens)
Source: HBRA (Dames and Moore, 1992b)
rd).dI'IUja.~.9'
-------
Table 5: Quantitative Summary of Daily Intake for Dermal Absorption of Ground Water
(page 1 of 2) .
Absorbed dose
Other Formula
Utitized:
.. CW x SA X Ko x EF x ED
CF x BW x AT
(Equation A)
log Kp . -2.72 + (0.71 x log Kow) - (0.0061 x MW) (USEPA, 1992b)
(Equation B)
(Equation A) Absorbed dose in (mgAtg~ay)
CW .. Exposure point chemical concentration in water (mgJI)
SA . Skin surface area available for contact (cm2)
Kp = Chemical-specific dermal permeability constant (cmJhr)
ET .. Exposure time per day (hrlday)
CF .. Conversion factor for volume and mass units (1 E+03 cm3ll)
EF .. Exposure frequency (dayslyear)
ED .. Exposure duration (years)
BW .. Body weight (kg)
AT .. Averaging time (days)
Kow .. OctanollWater partition coefficient (unitless)
MW .. molecular weight (atomic molecular units)
(Equation B)
;li!;.~ri~[tlfj;ffJi;~.
Light Industrial:
(Equation A)
Military
(Equation A)
l1t:t.It:;_11~~it1~~1~mJ:~;~~:ill:~fttfi!.~~tli~~~11i:i~1~;~~il:::~~fi;;::;~:~::~:::;;~:::;
SA
Kp
ET
EF
ED
BW
AT
.. 3,200 cm2 (adult upper extremities; USEPA, 1989a)
.. ChemicaJ-specific (see text)
.. 30 minlday or 0.5 hrlday (estimated time/WOrkday with hands on use of water source
(washing equipment. etc.»
.. 250 dayslyr (USEPA, 1991b)
.. 25 years (USEP A, 1991 b)
.70 kg (adult; USEPA, 1991b) .
.70 years x 365 dayslyr.. 25,550 days for carcinogens (USEPA, 1991 b)
.25 years x 365 dayslyr80 9,125 days for noncarcinogens (USEPA, 1991b) .
. 3,200 cm2 (adult upper extremities; USEPA, 1989a)
. Chemical-specific (see text)
. 30 minlday or 0.5 hrlday (estimated time/workdday with hands on use of water source
(washing equipment. etc.»
EF .. 250 da(sIyr (USEPA, 1991b)
ED .. 3 years (estimated duration of tour of duty)
BW ..75 kg (USEPA, 1989a)
AT . 70 years x 365 dayslyr . 25,550 days for carcinogens (USEPA, 1991 b)
.3 years x 365 daystyr .1.095 days for noncarcinogens (USEPA, 1991b)
SA
Kp
ET
rcb.dIrI.-ja.67062.Q./IL6'711M
-------
Table 5: Quantitative Summary of Daily Intake for Dermal Absorption of Ground Water
(Page 2 of 2)
E 3,200 cm2 (adult upper extremities; USEPA, 1989a)
c chemical specific (S99 text)
c 30 minlday or 0.5 hrlday (estimated daily average with hands on use of water source)
(washing equipment. watering tivestock, etc.)
c 365 dayslyr (farmer is assumed to work 365 dayslyr)
c 40 years (estimated duration of farme(s career)
'" 70 kg (USEPA, 1991b)
'" 70 years x 365 daysJyr - 25,550 days for carcinogens (USEPA, 1991 b)
.. 40 years x 365 dayslyr - 14,600 days for noncarcinogens (USEPA, 1991b)
(Equation B): KoW - chemical specific (see text)
MW - chemical specific (See text
(Equation B): log Kp - -2.72 + (0.71 x 2) - (0.0061 x 227.1) '"' -2.68
Kp .. 2.1 E-03 .(anlhr)
(Equation A): Absorbed dose .. CW (mom x 3 200 (an~) x 2.1E-03 (cmlhr) x 0.5 (hr/dav) x 365 (davs/Vr) x 40 (vrs)
1 E+O.3 cm3I1 ~ 70 (kg) x 2S.55O (or 14,600) (days)
- Cw (mgJI) x 2.7SE.QS (Iff(g-day) (carcinogens)
- Cw (mgJI) x 4.79E.Q5 (Iff(g-day) (noncarcinogens)
. (Equation A):
SA
Kp
ET
EF
ED
BW
AT
Source: HBRA (Dames & Moore. 1992b)
rd).dIft..llja.67062-62J11l6l71!M
-------
Table 6: Quantitative Summary of Daily Intake for Crop Ingestion
Intake. CC x IR x EF x ED
BW x AT
(Equation A)
For organics:
For inorganics:
CC . (CS x Ksp) + (CW x Kwp x CF)
Ksp . antilog (1.588-(0.578 log Kow) ( Travis and Arms.1988)
Kwp . Ksp x kd
Kd . antilog (-0.99+(0.53 log Kow) (Travis et aI., 1956)
CC . (CS x UFsp) + (CW x UFwp x CF)
(Equation B)
(Equation C)
(Equation D)
(Equation E)
(Equation F)
:tt~i:ili:~iii~'i~[~~~:i~~~rui;iI[~[ttt:i.~111fj!:[[~:lt!I~[:[:i[~!:::I[:[!~it]~illN;111!:iili[:~:~::[::ii:i:;i::::i:i:!i::;:i:[~~:i:::::::[:::::i:::;
~1_B81W~ij..'II::
(Equation A):
(Equation B):
, .
(Equation C):
(Equation D):
(Equation F):
Intake in (mgJkg-day)
CC . Contaminant Concentration in Crop (mgIkg)
IR . Ingestion rate of homegrown vegetables (kglday)
EF . Exposure frequency (dayslyear)
ED . Exposure duration (years)
BW - Body weight (kg)
AT - Averaging time (days)
CS - Contaminant concentration in surface soil (rngIkg) .
CW - Contaminant concentration in water (mgJI)
Ksp - Partition coeffICient between soil and plants (see Equation C; unitless)
Kwp - Partition coefficient between water and plants (see Equation D; unitless)
CF - 1/kg
Kow - OctanaI/Wat8r partition coefficient (unitleSS) .
Kd . Soil-waler partition coeffiCient (mgAqJ in soil per mgJI in water)
UFsp - Fresh weight plant uptake factor (unitless)
UFwp - Water-to-plant uptake factor (unitless)
ji~[l;M~t[~~:::
(Equation A):
(Equation C):
(Equation F):
IR - SOgiday or 0.080 kgldayfor homegrownvegetabJes (USEPA, 1991a)
EF - 3SO days/'fr (USEPA. 1991a)
ED -30 years (USEPA.1991a)
BW -70 kg (USEPA, 1991b) .
AT -70 years x 365 days/'/r - 25.550 days for carcinogens (USEPA. 1991b)
- 30 years x 365 daysIyr - 10.950 days for noncan:inogens (USEPA. 1991b)
Kow - Chemical specific (see text)
UFsp - Chemical specific (see text)
UFwp - Chemical specific (see text)
. (Equation C):
(Equation E):
(Equation D):
(Equation B):
(Equation A):
Ksp - antilog (1.588-(0.578 log 100» - 2.7 .
Kd - antilog (-0.99+(0.53 log 100» -1.17
Kwp -2.7 x 1.17 -3.16
CC - (CS x 2.7) + (CW x3.16)
Intake - CC tmalkQ) x 0.08 (1caJd~\ x gSO (dav~8ar\ x 30 (vears\
70 (kg) x 25.550 (or 10.950«days)
- CC (mgAcg) x 4.7E.04 (1/day) (carcinogens)
- CC (mgAcg) x 1.1E-03 (1/day) (noncarc:inogens)
Source: HBRA (Dames & Moore, 1992b)
rdI.drIf..67062.Q.JpUi176M
-------
obtained from EPA's Risk Assessment Guidance for Superfund. chronic daily intake
factors for each chemical within each exposure pathway for a given population at risk
were calculated.
2.6.1.3 Risk Characterization. The risk characteriUltion was conducted by combining
the toxicological data with the average daily intakes. Potential incremental cancer risks
are calculated by multiplying the daily intake averaged over the receptOr's lifetime by
the SF. Hazard indices are calculated for non-carcinogenic risks by dividing the
average daily intake by the RID. Carcinogenic risks and non-carcinogenic hazard
indexes are calculat~ for each pathway and then summed to yield the total site risk and
hazard index.
The tWo pathways shown in Section 2.6.1.2 were .quantitatively evaluated for the risk
. assessment at Site 4. The resulting hazard indices and risks are summarized in Table 7.
For the unconfined aquifer. the total carcinogenic risk is 3 x 10-3 and the total non- .
carcinogenic hazard index is 30.5.
The risk values reported for consumption of crops are estimated based on both soil and
ground water contamination, which resulted in elevated risk estimates when
considering only ground water. H crop consumption is eliminated from the total
<:arcinogenic and non-carcinogenic risks, the risk levels decrease. However, even
without crop consumption, the site presents risk levels that are outside the acceptable
risk range of 104 to 1()-6 for carcinogenic risk and greater than 1.0 for the non-
carcinogenic hazard inde~. . .
2.6.1.4 Uncertainty. Each step of the risk assessment process has some associated
uncertainty. The limitations include the adequacy of sampling, data quality, and the
assumptions inherent in the modeling of exposure point concentrations. Also included
is the uncertainty in toxicity data and exposure assumptions. In the evaluation of the
risks at UMDA, the most conservative plausible assumptions were made when faced
with uncenainty. Some of the uncertainties and associated conservative assumptions are
discussed below. The uncertainties can be found in more detail in Section 7.5 of the
HBRA (Dames & Moore, 1992b).
.
Future lAnd Uses. One of the main uncenainties concerning the future land uses
identified in the HBRA is the likelihood of .their actual occurrence near the
Explosives Washout Lagoons. The uncertainty here is that the washout lagoon site
is located on and near the Coyote Coulee, which would make agriculture and
residential uses difficult.
.
UpttJke Factors/or Crop Consumption Parhway. Many assumptions are built into
. the calculation of contaminant levels in crops. The uptake of contaminants is based
on models and not actUal field testS and in some cases the predicted values may be
higher than viable for the growth of crops.
Exposwe Frequency and Duration Values/or Future Land Use. A number of
uncertainties are associated with estimates of how often, if at all, future populations
would be exposed to contaminants in the ground water and the period of time over
which these exposures would occur.
.
rcb.drrI.aja.67062.Q.1pL617~
-------
Table 7: Carcinogenic Risks and Non-carcinogenic Hazards-
Future Residential Land Use Scenario
Pathway Description
Carcinogenic
Risk (8)
Non-
Carcinogenic
Risk (b)
Ingestion 01 .
Ground Water
3.00E-03
30
Dermal Absorption 01
Ground Water
Contaminants During
Showering
2.00E-06
0.5
Totals
3.00E-03
30.5
Notes
(a) - Excess lifetime cancer risks to an individual
(b) - HI (an HI of 1.0 of lower generally indicates that no adverse effects would be expected)
Source: Dames & Moore, 1992b
rdI.ctm.8ja.67tl62-62.IJX.&719f
-------
.
Standard Assumptions. Standard assumptions used throughout the HBRA (e.g.,
body weight, drinking water ingestion rates) are based on EP A guidance. These
standard assumptions are used to calculate reasonable maximum exposure
estimates to obtain risk estimates that are both protective and reasonable. Risks for
certain individuals may be higher or lower depending on the values actUally
applicable to them.
Toxiciry Info171l£Jfion. General toxicity assessment uncenainties include lack of
substantial data on the toxicity of some contaminants, derivation of.toxicity values
from animal studies, calculation of lifetime cancer risks on the basis of less-than-
lifetime exposures, and potential synergistic or antagonistic interaction with other
substan~s affecting the same individuals. .
.
Toxiciry Info171l£Jfionjor TNB. No adequate toxicity or carcinogenicity data exist
for TNB. The oral reference dose is based on a subchronic stUdy in the structural
analog DNB and is adjusted for molecular weight differences. The uncertaintY
factor of ' ') ,QOC ased in the derivation of TNB reference dose includes' factor of
10 for crilmon determination by analogy. The Army is currently conducting
toxicity teStS on TNB to better determine what the toxicity effects are. The results
of these studies will be used to reevaluate the risks posed by the ground water and
the risk-based cleanup level for TNB. .
The uncenainties presented above are propagated through the estimation of risk
performed in the risk characterization in a multiplicative fashion. Uncertainties, .
likewise, are associated with the presentation of total risk values for an exposure zone
and scenario:
.
.
Total scenario risks do not reflect potential synergistic or antagonistic effects of '.
complex mixtUreS.
Total maximum scenario risks are based on individual analyte risks at the unique
location of maximum compound concentration. The method of estimating risk: is,
therefore, conservative and proteCtive of human health.
.
Risks were riot quantified for some pathways, consequently, large uncertainty is
associated with total site risks.
2.6.2 Environmental Evaluation .
Since the contaminlltM ground water is not easily accessible to any wildlife, it is not
expected to present a substantial threat to the local enviropment. The most likely
exposure pathway would be through ingestion of crops that have been inigated with
CODU'minllterl ground water. However, EPA, with concurrence from the Army and the
State of Oregon, has dete11Dined that the crop ingestion pathway is not a likely exposure
pathway at the washout lagoons due (0 the slope and sandy nature of the soils. which
generally make the site unusable for agriculture.
.
2.7 DescrIption of Alternatives
The Anny's and EPA's selection of an alternative for the remediation of the Explosives
Washout Lagoons Ground Water, as described in this ROD, is a result of a
comprehensive evaluation and screening process. An FS was conducted to identify and
rcU"".aja.67062~""
-------
analyze the various alternatives considered for addressing the remediation of the site.
The FS repon for the lagoons ground water describes the alternatives considered, as
well as the process and criteria the Anny used to narrow the list to four potential
remedial alternatives. (For details on screening methodology, see Sections 2 and 4 of
the Explosives Washout Lagoons Ground Water FS repon [Anhur D. Little, 1993]).
2.7.1 Ground Water Cleanup levels
The ultimate goal of the cleanup at the Explosives Washout Lagoons is to protect
human health and the environment from exposure to contaminated ground water. The
cleanup objectives for the ground water are therefore proposed as follows:
.
Eliminate or minimize the potential threat to human health and the environment by
preventing exposure to ground water contaminants
Prevent further migration of ground water contamination beyond its cUrrent extent
.
Restore co :aI.I'I..~.lated ground water to a level that is protective of human health and
the environment, as soon as practicabl~
To meet these objectives, the Army and EPA have selected a ground water pump and
treat system to Stop the spread of contamination, and site-specific ground water cleanup
levels that will be proteetive of human health and the environmenL Oeanup levels have
been established in ground water for the contaminantS of concern identified in the
HBRA to pose an unacceptable risk to human health. The cleanup levels have been set
based on the ARARs as available. or other suitable criteria described below. Periodic
assessments of the proteetion afforded by the remedial actions will be made as the
remedy is being implemented and at the ".ompletion of the remedial action.
.
aeanup levels presented in this ROD (Table 8) for known, probable. and possible
carcinogenic compounds (Classes A. B, and C) have been established to proteCt against
potential carcinogenic effects and to conform with Human Health Advisories. (EP A
Health Advisories were considered as TBC criteria when setting ground water cleanup
levels for RDX. TNT, and HMX. The other four explosives did not have health
advisories.) aeanup levels for compounds that are not classified or have no evidence of
carcinogenicity (aasses D and E) have been established to proteCt againSt potential
non~ogenic effects and to conform with Human Health Advisories.
In the absence of a Human Health Advisory. a cleanup level was derived for each
compound having carcinogenic potential based on a 1 x 1(}-6 excess cancer risk level
per compound, considering the ingestion of and dermal contact with the ground water.
In the absence of the above Standards and criteria. cleanup levels for all other .
compounds were established based on a level that represents an acceptable exposure
level to which the human population, including sensitive subgroups. may be exposed
without adverse effect dming a lifetime or part of a lifetime. incorporating an adequate
margin of safety (hazard quotient equal to 1) considering the ingestion of and dermal
contact with the contaminated ground water.
If a value described by any of the above methods was not capable of being detected
with good precision and accuracy, then the practical quantification limit was used for
the ground water cleanup level.
rdMIrrI.8ja.61062~6I7""
-------
Table 8: Remedial Action Criteria for the Ground Water at the Explosives Washout
Lagoons
Contaminant Remedial Action
01 Concern Criteria Basis Level 01 Risk Hazard Index
(ug/L)
TNB 1.8 Risk-Based 1
DNB 4.0 Risk-Based 1
TNT 2.8 Risk-Based 1.00E-06
2,4-DNT 0.6 PQl 4.00E-06
2,6-DNT . 1.2 POL 5.00E-06
t-MX 350.0 Health Advisory '0.2
R»( 2.1 POL 3.00E-06
Total Excess Risk 1.30E-05 2.2
pal = Practical Ouantitation Umit
.mAnfAja.b/OOZ ~ 5/7/81.
-------
These cleanup levels are consistent with ARARs or suitable TBC criteria for ground
water, attain the NCP risk management goal for remedial actions, and are determined
to be protective. The risk assessment also showed significant risk for arsenic in ground
water. However, arsenic concentrations in the ground water at UMDA were consistent,
showing that the concentrations around the washout lagoons are due to regional
background. Also the concentrations are below the MCL of 50 J.Lg/L. Therefore, no
cleanup is required for arsenic.
All ground water cleanup levels identified in this ROD must be met at the completion
of the remedial action at the points of compliance, the edge of the Washout Lagoons.
The Army has estimated that these levels will be obtained within 10 to 30 years after
startup of the remedial action. .
. 2.7.2 Alternative Descriptions. .
After screening numerous potential remedial responses (Arthur D. Little, 1993), four
remedial alternatives (including no action) were developed for the Explosives Washoe:
Lagoons Ground Water. Variations of two of these alternatives were also evalualdi to
give a total of six rcnedial alternatives: .
Alternative 1: No Action (Required by law to be considered)
Alternative 2: Institutional Controls (Monitoring and Controlled access)
Alternative 3A: UV/Oxidation and Reinfilttation of Treated Ground Water (30 years)
Alternative 3B: UV/Oxidation and Reinfilttation of Treated Ground Water (10 years)
Alternative 4A: Granular Activated Carbon (GAC) and Reinfiltration of Treated
Ground Water (30 years)
Alternative 4B: Granular Activated Carb'\n (GAC) and Reinfiltration of Treated
Ground Water (10 years)
The following sections describe the selected remedy (Alternative 4B) and the other
alternatives retained for detailed analysis.
2.7.2.1 Alternative 1 - No Action. Both CERCLA and ODEQ regulations require that
a "No Action" alternative be evaluated for every site to establish a baseline for
comparison. No Action means that no response to contamination is made, activities
previously initiated are abandoned, and no further active human intervention occurs.
. .
This alternative assumes that no treattnent or restrictions would be placed on the
contaminated ground water either now or when UMDA is released to the public. The
only reduction in the contamination levels would be through dilution and natural
processes and these processes could take as long as 5,000 years to reduce the
contaminant concentrations to below the selected cleanup levels. Because this
alternative would not reStrict ground water flow and would not treat ground water,
migration of contaminants would continue. Based on modeling performed in the FS, the
contamination would reach the UMDA boundary in approximately 70 years.
The No Action alternative would, however, require five-year reviews intended to
evaluate whether the alternative remains protective of public health and the
environment.
Costs associated with this alternative would be generated only by five-year reviews.
RtI.dIn..aja.67'D62-62JpL617~
-------
Capital Cost: None
Operating and Maintenance Cost: $4,000 annually
Total Net Present Value: $81,000
Time for Restoration: estimated 5,000 years
2.7.2.2 Alternative ~ - Institutional Controls. This alternative would place legal
restrictions on the in.;tallation of wells into the contaminated ground water. The access
restriction would be a state or local legal restriction in the study area where
contaminated ground water has been found. This legal restriction would have tWo
purposes: .. . .
.
Land use restriction on the site to prevent future residential development where.
contaminants in the ground water are at concentrations greater than the cleanup
levels.
.
Ground water restrictions to, prohibit the installation of new wells in the
contaminated portion of the alluvial aquifer or the basalt layers underlying the
contamination. Tbese restrictions would have to be expanded in the future to
include restrictions on the existing ground water wells if any of these wells are
found to be contaminated. .
Tbe legal restrictions would be maintained until the cleanup levels are met or the SIte is
determined not to pose a threat to human health or the environment. The alternative
would also require the continued monitori:1 g of the ground water and five-year reviews.
No treatment or removal of ground water would be included in this alternative. The
only reduction in the contamination levels will be through dilution and natoral
processes, and these processes could take as long as 5,000 years to reduce the
contaminant concentrations to below the selected cleanup levels. Because this
alternative would not restrict ground water flows and would not treat ground water,
migration. of contaminants would continue. Based on modeling perf~ed in the FS, the
contamination would reach the UMDA boundary in approximately 70 years. Long-term
environmental monitoring would be conducted for at least 70 years. . .
This alternative would be proteCtive of human health in that it would restrict the access
to the contaminated portion of the aquifer and would have no adverse shan-term
impacts because the coIitaminated portion of the aquifer is not used. However, as the
plume continues to migrate it may impact the use of off-site ground water when the
contamination reaches the UMDA boundary.
Capital Cost: $10,000
Operating and Maintenance Cost: $40,000 annuany
Total Net Present Value: $820,000
Time for Restoration: estimated 5,000 years
rcb.dIN.aja.67062.Q.IIL&17.1M
-------
2.7.2.3 Alternative 3 - Ultraviolet/Oxidation - 1D-Year or 3D-Year On-Site
Treatment Using UV/Oxldatlon Followed by Relnf/ltratlon 0' the Treated Ground
Water. In this alternative, the ground water would be extracted from several wells
(three wells have been assumed in the FS) over a 3D-year (Alternative 3A) or lO-year
(Alternative 3B) period to clean up the aquifer to the cleanup levels presented in Table
8, and to stop the spread of the ground water contaminant plume. The 30- and 10- year
alternatives differ only in the pumping rates by which the ground water is extracted for
treatment. The ground water would be treated by hydroxide precipitation to remove the
background metals from the contaminated ground water and then treated by
UV foxidation to destroy the explosives (Figure 6). The results of recent treatability
studies indicate that it is not economically feasible to utilize UV foxidation for complete
cleanup. Therefore, granular activated carbon (GAC) with off-site thermal treatment of
the spent carbon would be included as a polishing step to the primary UV foxidation
treatment. .
After the extraCted ground water has been treated and meets all performance standards,
based on grour ~ water cleanup levels. a portion of the treated water would initially be
pumped to the Explosives Washout Lagoons. where it would be allowed to reinfiltrate
into the subsurface soils under the lagoons. The additional treated ground water would
be pumped to a reinfiltration gallery 400 to 800 feet upgradient of the lagoons.
Reinfiltration of the treated ground water into the subsurface soils would flush the
remaining low level soil contamination beneath the lagoons into the ground water,
where it would be collected downgradient in the extraetion wells. After approximately
one year the reinfiltration of all of the treated groundwater would be moved to the
infiltration galleries. . '.
/nsUtutionaJ Controls. While the ground water is being remediated. institutional
conaols would be needed to restrict access to the conClminated aquifer, the .
contaminated ground water remediation equipment, and the interConnecting piping. The
access restriction would be a state or local legal restriction in the stUdy area where
conClminated ground water has been found. This legal restriction would have three
components:
.
Access restriction to the site to prevent direct human exposure to conVtminants.
Land use restriction on the site to prevent future residential development where
contaminants in the ground water are at concentrations greater than the ground
water cleanup levels.
.
.
Ground water restrictions to prohibit the installation of new wells in the
contaminated portion of the alluvial aquifer or the basalt layers underlying the
contamination.
The legal restrictions would be maintained until the ground water cleanup levels are
met or the site is determined not to pose a threat to human health or the environment.
MonItoring. The monitoring program for the Explosives Washout Lagoons ground
water has been designed based on the results of the RI and should be modified as the
aquifer is remediated. The objective of the program would be threefold:
.
To monitor for changes in contaminant concentrations
rcD.dmI.aja.67062~6I7""
-------
Figure 6: Conceptual Flow DIagram of UV/Oxldatlon of ContamInated Ground Water
il
I
I
OW EKtracllon Wells
EqullIl8t1onf
""II nil Tlnk
'Sollde
to Oil. Site DtlpOII'
source: Arthur D. Llnle.1993
!:S
~
M,t.1 Hydroxide
Sludge to O".SlIe
Dllpolal .
Olone
OlltNcUon
Unit
UVloxtdlUon Rllctor
OAC Oround Wllter Polllhing
Spent GAC 10 01l.5ilo
Thermol Treotmenl
Trentnd Ground
-------
.
To ensure that contaminants do not migrate off UMDA or the restricted ground
water area in excess of risk-based cleanup levels
To ensure that the in-situ soil flushing of the lagoons does not cause the ground
water contamination to spread
.
The program would monitor the unconfined aquifer on a semiannual basis for .
explosives and metals. The sampling frequency would be reduced to annually if the
semiannual monitoring results are found to be similar during the fIrSt five-year review.
Five- Year Reviews. The objective of the five-year reviews is threefold: (1) to col1fmn
that the remedy as presented in the ROD and/or remedial design remains effective for
the protection of human health and the environment (e.g., the remedy is operating and
functioning as designed, instimtional controls are in place and are proteCtive); (2) to. .
evaluate whether original cleanup levels remain proteCtive of human health and the
environment; and (3) to ensure that there is no human contaCt with the ground watf"T
contamination.
For this alternative, the review would focus on both the effectiveness of the GAC
system, off-site thermal treatment of the GAC, and the specific performance levels
established in the ROD.
. The first objective of a five-year review would be accomplished primarily through a
review of documented operation and maintenance of the site, a: site visit, and limited .
analysis of site conditions. The second objective requires an analysis of newly
promulgated or modified requirements of federal and state environmental laws to
determine if they are ARARs and/or if they call into question the protectiveness of the
remedy (NCP Section 3OO.43O(f)(1)(ii)(B)(l». For example, new federal or state MCLs
may be promulgated at a more .stringent level, calling into question the proteCtiveness
of a ground water pre1iminmy remedial goal set at the risk-based cleanup level. The
state would be requested to identify state ARARs promulgated or modified since ROD
signature that may have a bearing on the protectiveness of the remedy.
A further objective of the five-year review is to consider the scope of operation and
maintenance (O&M) activities, the frequency of repairs, changes in IIlQnitorlng .
indicators, rosts at a site, and how this relates to protectiveness. If O&M activities
either grow unexpectedly over time or are simply much greater than had been estimated
at the time of remedy selection, the reviewer would analyze O&M activities and cost
increases in an effort to determine if such increases are an early indicator of the
deterioration of the remedy. Rising efforts.or costs may indicate that excessive attention
or activity is required to ensure that a remedy functions properly. This rise might be due
to the deterioration or inefficiency of the remedy. In this case, repair or further actions
. may be necessary to protect against a higher than acceptable potential for remedy
failure. Based on such an analysis, the Army and the EP A, in consultation with the
state, would consider whether funher actions should be taken to reduce increasing
O&M activities. As appropriate, the Army may also propose additional response
actions to reduce O&M activities or contain rising O&M costS.
Ground Water ExtraCtion. To calculate the rate of ground water extraCtion and well
spacing for the source containment and the aquifer remediation system, the MOC
Model was used (see Section 2.3.3, Ground Water Modeling Results, of the FS report
[Arthur D. Little, 1993]). The results of the model indicate that three wells with a total
rd).dnf.aja.67062-62.1fIL6I7f1J4
-------
pumping rate of approximately 140 gallons per minute (gpm) for 30 years or
approximately 330 gpm for 10 years would be needed to remediate the ground water
aquifer to the cleanup levels. The capture zone extends beyond the known
contamination and captures the water discharged to the reinf1ltration gallery or the
washout lagoons.
The ground water pumped from these wells would be collected and pumped via. a
buried pipeline, to protect against potential freezing problems, into the ground water
treatment building. The aeattnent building would be constructed to proteCt the
processing equipment from adverse weather conditions and to help keep the treatment
process at a moderate (emperature, which would increase the contaminant removal
efficiency.
Over the estimated remediation time of 10 to 30 years, an estimated 1.7 to 2.2 billion
gallons of contaminated water would be extraeted from the aquifer for aeattnent. There
is some uncertainty associated with meeting the ground water cleanup level with the
estimated extraetion rate and remediation time because of the adsorption of the
contaminants to the aquifer materials. Because there is little l-istorical data tC' -tetennine
how these contaminants will desorb from the aquifer materials, an evaluation of the
remedial action will be important during the five-year review in order to ensure. that the
continuous pumping of the aquifer is the best method of attaining the ground water
cleanup levels. At the five-year review, other options such as pulse operation of the
extraCtion wells should be considered if the remedial action is not achieving the
anticipated results.
Equalization. . The extracted ground water would be pumped to an equa1i7~tion tank,
which would provide at least a 50-minute retention time. The tank will be sized to
allow mixing and equalization of the ground water from the extraetion wells, thereby
ensuring a relatively uniform feed concentration to the treatment equipment The
eq1)a1i7~tion tank would also be used as a settling tank to remove any solids from the
ground water. Any solids that are collected during the remediation would be drummed
and analyzed to ensure that they were not a RCRA hazardous waste, and if they are not
hazardous, sent to an off-site industtiallandfill for disposal. If the solids were found to
be a RCRA hazardous waste they would be sent off site for treatment in accordance
. with RCRA land disposal requirements.
lfefal precipitation. The ground water would be pumped from the eqnali7~tion 1aI1k to
the metals precipitation unit for treatment to tninim17.e the potential for fouling the UV
lights; this system should also reduce any eJevated metal concentrations to below
naturally occurring background levels. The metals precipitation process would include
an oxidation system. pH adjustment vessel, a stirred reactor, a clarifier to remove
ptecipitated metals, and a multimedia filter to remove any remaining suspended solids.
The collected precipitated solids would be dewatered to reduce the volume and to make
handling easier. The water from the dewatering oPeration would be recycled back to the
equalization tank. The precipitation system would produce between 0.5 and 1.2
tonS/day and an estimated 4,400 to 5.300 tons over the entire remediation. .
The dewatered solids from the metal precipitation process will be analyzed to
determine if the solids are a RCRA hazardous waste. H they are found to be hazardous
they will be disposed of off site in accordance with RCRA land disposal restrictions.
rd).CIn'I",67082~S4
-------
UV/Oxldation. After the metal precipitation system, the pH of the ground water would
be adjusted to a value of 6 to 7 and pumped to the UV/oxidation system The
UV loxidation system would be operated with ozone (03) as the oxidant, based upon the
results of the Milan Anny Ammunition plant treatability stUdy that indicated that
hydrogen peroxide is not an effective oxidant for a similar waste stream. For design and
costing purposes only, an 03 system was selected. However, in the remedial design for
the ground water at the Explosives Washout Lagoons, the choice of oxidant(s) to use
should be .based on additional data to be provided as a result of the conduct of the
treatability study currently being perfonned at UMDA.
The 03 would be added to the extraCted ground water stream at an estimated rate of 2
mg/Umin as it passed through the reactor system. The reactorS would provide a
minimum UV light intensity of 0.07 kwlL of ground water with a residence time of 45
minuteS, and would be modular in design. The modular design would allow banks' of
lights to be shut down as the contaminant loading decreased over time, thus ensuring an
economically efficient treatment system for the lifetime of the project. A 90 percent
destruction of C~ total explosives concentration should be achieved using the operating
parameters described above. This overall destrUction value is limited by the fact that
TNT is oxidized to TNB, which then takes a comparable amount of time to be oxidized
to harmless constituents. The other compounds present in the contaminated plume have
been shown to degrade to water, carbon dioxide, and nitrates within this 45-minute
retention time.
. The UV/oxidation system would have a cleaning mechanism for the quartz tubes. to .
reduce the fouling of the blbes, which would otherwise reduce the UV emittance. After
leaving the UV reactor, the treated ground water would require final polishing by a
GAC system to remove residual TNB produced by the oxidation of the TNT. It would'
not be economical to operate the full-sized UV loxidation system for TNB removal, as
this would require an additional 30 minutes of treatment time, thereby significantly
increasing operating expenses. The GAC system will also act as a remedial backup in
the event of a UV loxidation system malfunction.
GAC Polishing. The GAC polishing unit would be two parallel treatment trains
consisting of an estimated 2,OOO-pound carbon beds contained in tanks sized to allow
for adequate absorption time. The carbon beds would not be operated until satUration,
but rather only until an average 0.07 pounds contaminant per pound GAC loading was
achieved. This ceiling on loading is to ensme that the adsorbed contaminantIGAC
matrix does not approach its explosive limit and, therefore, would not be considered a
RCRA c~tic waste. When teSt results indicated that the carbon bed is spent, the
polishing system would be switched over to the standby bed. The carbon utilization rate
is estimated to be between 13 and 30 pounds/day based upon the design flow rate and
expected UV loxidation system effluent concentration. The total carbon use rate for the
remediation is estimated to be 55 and 70 toDS. .
To change the spent carbon, untreated water from theequ~li7.ation vessel would be used .
to slurry the column into a hopper. The GAC would be allowed to gravity drain for
approximately 24 hours, and would then be screw-fed from the hopper into drums. The
water drained from the hopper would be collected and recirculated back to the
equalization vessel for treatment.
The drums containing the spent, but non-sanmued, carbon would be analyzed to ensure
that the explosives level 'Yas below 10 percent and that it did not exceed the TQ..P limit
~t94
-------
for 2,4-DNT. If the carbon passed the analyses, it would be shipped off site for thennal
treatment (e.g., incineration, cement kiln, regeneration).
Relnflltratlon. After the ground water has been treated and meets all cleanup levels,
the water would initially be pumped to the Explosives Washout Lagoons or both the
lagoons and an up gradient inf1lttation gallery. where it would be allowed to reinfiltrate
into the aquifer. Reinfiltration of the neated ground water into the lagoons would help
flush the remaining soil contamination into the ground water table, where it would be
collected down gradient in the extraction wells. The flushing of the soil contamination
would take approximately tWelve months. The ability to remove the explosives through
in-situ flushing is uncertain and would require close monitoring during the remedial .
action to ensure that the contaminants are not being spread into currently
uncontaminated regions. If the contaminants are found to be spreading into
. uncontaminated regions, then the reinfiltration to the lagoons would be stopped until.
further options can be evaluated. The in-situ flushing is not a required part of the
ground water remedy, since the subsurface lagoons soils required no remediation under
the Explosives Washout Lagoons Soil ROD. In-situ flushing is only a cost-effective
means of removing additional soil contamination by taking advantage of the reG aired
infiltration of the treated ground water.
The infiltration of the ground water into the lagoons would be completed by laying
perforated PVC piping in 2 feet of crushed stone at the bonom of the excavated
lagoons. A liner would then be placed over the stone and the treated soil from the
composting system would .be placed on top of the liner. The actual design of this
distribution system needs to be investigated further during the remedial design to
calculate a peICOlation rate and ensure that the ground water is evenly distributed over
the lagoons and all areas are flushed. .
After approximately tWelve months, the reinfiltration of the treated ground water would
be directed to an infiltration gallery 400 to 800 feet upgradient of the lagoons. There are
a number of different types of systemS that could be used to provide these infiltration
areas. These include such systems as leaching pits, fields, trenches. or galleries. For the
purpose of the FS,leaching galleries were selected; however, during the remedial
design, one of the other types of systemS may be selected. A leaching gallery is a 4 by 4
by 4 foot conctete box with tWo open ends and perforated sides artd bonom. These .
boxes are linked together into rows that provide both infiltration area and some level of
stOrage if there are fluctuations in the flow rate to the leaching galleries. In sizing the
leaching galleries, only the bottom area of the leaching galleries was considered even
though there will be some infiltration through the side walls. This provides some extra
capacity for the system if the percolation rate is lower than assumed or if additional
pumping is required to meet the cleanup levels.
Alternative 3A - 3O-year on-site treatment
Capital Cost: $2,100,000
Operating and Maintenance Cost: $770,000 annually
Total Net Present Value: $14,300,000
Time for Restoration: 30 years
r=.dmf~QIpL6f7J901
-------
Alternative 3B -IO-year on-site treatment
Capital Cost: $3,600,000
Operating and Maintenance Cost: $1,600,000 annually
Total Net Present Value: $16,200,000
Time for Restoration: 10 years
2.7.3.4 Alternative 4: GAC Treatment - to-Year or 3O-Year On-Slte Tteatment
Using GAC Followed by RelnflltrBtlon of the Treated Ground Water. In this
alternative, the ground water wiU be extracted from several wells (three wells have
been assumed in the FS) over a 3O-year (Alternative 4A) or a to-year (Alternative 4B)
period to remediate the aquifer to the cleanup levels presented in Table 8, and to stop
the spread of the ground water contaminant plume. The 30- and t Q-year alternatives
differ only in the pumping rates by which the ground water is extraCted for treatment.
The ground water will be treated by GAC to remove the explosives (Figure 7). The
spent carbon from the GAC treatment beds would be thermally treated off site.
After the ground water has been treated and meets all the perfonnance standards, based
on the ground water cleanup levels, a portion of the treated water will initially be
pumped to the Explosives Washout Lagoons, where it will be allowed to reinfiltrate
into the soils under the lagoons. The additional treated ground water will be pumped to
the reinfiltration gallery 400 to 800 feet upgradient of the lagoons. Reinfiltration of the
treated ground water into the lagoons will flush some of the remaining low level soil
contamination into the ground water, where it will be collected downgradient in the
extraCtion wells. After approximately one year, the reinfiltration of all of the treated
ground water will be moved to infiltration galleries.
1nstltuU0nal Controls. While the ground water is being remediated. institutional
controls will be needed to restrict access to the contamin~ted aquifer, the contaminated
ground water remediation equipment and the interCOnnecting piping. The access
restriction would be a state or local legal resttiction in the study area where
contaminated ground water has been found. This legal restriction would have three
cOmponents: . .
.
Access restriction to the site to prevent direct human expos~ to contaminants.
Land use restriction on the site to prevent future residential development where
contaminants in the ground water are at concentrations greater than the ground
water cleanup levels.
.
.
Ground water ~strictions to prohibit the installation of new wells in the
contaminated portion of the alluvial aquifer or the basalt layers underlying the
CODtamination. These restrictions would have to be expanded in the future to
include restrictions on the existing ground water wells if any of these wells are
found to be contaminated in excess of the preliminary remedial goals.
The legal restrictions would be maintained until the ground water cleanup levels are
met or the site is determined not to pose a threat to human health or the environment
rd).dn'I~
-------
Figure 7: Conceptual Flow Diagram of Primary GAC Treatment of Contaminated Ground Water
OW Extraction Wells
Equlllzatlonl
81ttllng Tlnk
Prlmery GAC Ground Water Treetmlnt
Spent OAC Ilurrled Into
drelnage hopper using
untreated water Irom
equallzation/lellllng tank
+
Solidi.
10 on-Slle Disposal
Trealed Ground
Water Ir Relnliltration
Gallerlel
Dralnaga Water to
Equalization/Settling Tank
,
1
I
Source: Arthur D. Llttle.1993
fj
Orelnlg8 Hopper
Screw
Feeder
Spenl GAC
10 Drums
10rOIl-sile
Thermal
Trealment
-------
Monitoring. The monitoring program for the Explosives Washout Lagoons ground
water has been designed based on the results of the RI and should be modified as the
aquifer is remediated. The objective of the program would be threefold: .
.
To monitor for changes in contaminant concentrations
To ensure that contaminants do not migrate off UMDA or the restricted ground
water area in excess of risk-based cleanup levels
.
To ensure that the in-situ soil flushing of the lagoons does not cause the ground
water contamination to spread
The program would monitor the unconfined aquifer on a semiannual basis for
explosives and metals. The sampling frequency would be reduced to annually if the .
semiannual monitoring results are found to be similar during the first five-year review.
FIve-Year Rev~~ws.1be objective of the five-year reviews is threefold: (1) to confirm
that the remedy as presented in the ROD and/or remedial design remains effective for
the protection of human health and the environment (e.g., the remedy is operating and
functioning as designed. institutional conU'Ols are in place and are proteCtive); (2) to
evaluate whether original cleanup levels remain proteetive of human health and the
environment; and (3) to ensure that there is no human contaCt with the ground water
cont1nnination.
.
For this alternative, the review would focus on both the effectiveness of the GAC
system, off-site thermal treatment of the GAC, and the specific performance levels
established in the ROD.
The first objective of a five-year review would be accomplished primarily through a
review of documented operation and maintenance of the site, a site visit, and limited
analysis of site conditions. The second objective requires an analysis of newly
promulgated or modified requirements of federal and state environmental laws to
determine if they are ARARs and/or if they call into question the proteetiveness of the
remedy (NCP Section 3OO.43O(f) (l)(ii)(B)(l». for example, new federal or state MCLs
may be promulgated at a more stringent level, calling intO question theproteetiveness
of a ground water pre1iininary remedi,l goal set at the .risk-based cleanup level. The.
state would be requested to identify state ARARs promulgated or modified since ROD
signature that may have a bearing on the protectiveness of the remedy. .
A further objective of the five-year review is to consider the scope of O&.M activities,
the frequency of repairs, changes in monitoring indicatorS, COStS at a site, and how this
relates to protectiveness. If O&M activities either grow unexpectedly over time or are
simply much greater than had been estimated at the time of remedy selection, the
reviewer would analyze O&M activities and cost increases in an effort to determine if
. such increaseS are an early indicator of the deterioration of the remedy. Rising efforts or .
COSts may indicate that excessive attention or activity is required to ensure that a
remedy functions properly. This rise might be due to the deterioration or inefficiency of
the remedy. In this case, repair or further actions may be necessary to proteCt against a
higher than acceptable potential for remedy failure. Based on such an analysis, the
Army and the EP A, in consultation with the state, would consider whether further
actions should be taken to reduce increasing O&M activities. As appropriate, the Army
rdI..dn'I~WIM
-------
may also propose additional response actions to reduce O&M activities or contain
rising O&M costs.
Ground Water Extract/on. To calculate the rate of ground water extraction and well
spacing for the source containment and the aquifer remediation system. the MOC
Model was used (see Section 2.3.3. Ground Water Modeling Results, of the FS repon
[Arthur D. Little, 1993]). The results of the model indicate that three wells with a total
pumping rate of approximately 140 gpm for 30 years or approximately 330 gpm for 10
years would be needed to remediate the ground water aquifer to the cleanup levels. The
capture zone extends ~yond the known contamination and captures the water
discharged to the reinfiltration gallery or the washout lagoons.
The ground water pumped from these wells would be collected and pumped via a
. bmied pipeline. to proteCt against potential freezing problems. intO the ground water
treatment building. The treatment building would be constrUcted to proteCt the
processing equipment from ~verse weather conditions and to help keep the treannent
process at a moderate temperature, which would increase the contaminant rr -:10"~
efficiency .
Over the estimated remediation time of 10 to 30 years 31) estimated 1.7 to 2.2 billion
gallons of contaminaled water would be extraeted from the aquifer for treatment. There
is some uncenainty associated with meeting the ground water cleanup level with the
estimated extraction rare and remediation time because of the adsorption of the
CODVlminants to the aquifer materials. Because there is little historical data to determine.
bow these contaminants will desorb from the aquifer materials. an evaluation of the
remedial action will be important during the five-year review in order to ensme that the
continuous pumping of the aquifer is th", best method of attaining the ground water
cleanup levels. At the five-year review. other options such as pulse operation of the .
extraCtion wells should be considered if the remedial action is not achieving the
anticipated results
Equal/zstlolJ. The extraeted ground water would be pumped to an eqna1i7~tion tank,
which would provide at least a 5O-minute retention time. The tank will be sized to
allow mixing and equalization of the ground water from the extraction wells. thereby
ensuring a relatively uniform feed concentration to the treatment equipment The
eqlUl1i7.arion tank would also be used as a settling tank to remove any solids from the
ground water. Any solids that are collected during the remediation would be drummed
and analyzed to ensme that they were not a RCRA hazardous waste, and if they are not
hazardous. sent to an off-site industrial landfill for disposal If the solids were found to
be a RCRA bazaIdous waste they would be sent off site for treatment in accordance .
with RCRA land disposal requirements. ..
GAC Primary Tteafment The ground water would be pumped from the equalization
tank to.tbe.GAC primary treatment beds without metals precipitation. The primarY
. treatment carbon absorbers would be sized to reduce the explosive ground water
conbminants to cleanup levels without the use of any other treatment.
The GAC polishing unit would be tWo parallel treatment trains consisting of 2,000-
pound carbon beds contained in tanks sized to allow for adequate absorbent time. The
carbon beds would not be operated until satUration, but rather only until an average
0.07 pound contaminant per pound GAC loading was achieved. This ceiling on loading
is to ensure th~t the adsorbed contaminant/GAC matrix does not ap~ch its explosive
rdI.dmI.llja.67062~.1M
-------
limit and therefore. would not be considered a RCRA characteristic waste. When test
results indicated that the carbon bed is spent, the polishing system would be switched
over to the standby bed. Carbon usage is estimated to be between 125 and 310
pounds/day based upon the design flow rate. Total carbon usage for the remedial
alternative is estimated as 570 to 680 tons.
To change the spent carbon, untreated water from the equalization vessel would be used
to slurry the column into a hopper. The GAC would be allowed to gravity drain for
approximately 24 hours, and would then be screw-fed from the hopper into drums. The
water drained from the hopper would be collected and recirculated back to the
equalization vessel for aeatment.
Th~ drums containing the spent. but non-saturated, carbon would be analyzed to ensure
that the explosives level was below 10 percent and that it did not exceed the TCLP limit.
for 2,4-DNT. If the carbon passed the analyses, it would be shipped off site for thermal
treatment (e.g., incineration, cement kiln, regeneration).
RelnflltratJon. After the ground water has been treated and meets all cleanup levels,
the water would initially be pumped to the Explosives Washout Lagoons or both the
lagoons and an upgradient infiltration gallery, where it would be allowed to reinfiltrate
into the aquifer. Reinfiltration of the treated ground water into the lagoons would help
flush the remaining soil contamination into the ground water table, where it would be
collected downgradient in the extraetion wells. The flushing of the soil contamination
would take approximately twelve months. The ability to remove the explosives through
in-situ flushing is uncertain and would require close monitoring during the remedial
action to ensm:e that the contaminants are not reing spread into currently
uncontaminated regions. If the contaminan~ are found to be spreading into
uncontaminated regions, then the reinfiltration to the lagoons would be stopped until
further options can be evaluated. The in-situ flushing is not a required part of the
ground water remedy, since the subsurface lagoon soils required no remediation under
the Explosives Washout Lagoons Soil ROD. In-situ flushing is only a cost-effective
means of removing additional soil contamination by taking advantage of required
reinfiltration of the treated ground water. .
The infiltration of the ground water into the lagoons would be completed by laying
perforatedPVC piping in 2 feet of crushed stone at the bottom of the excavated
lagoons. A liner would then be placed over the stone and the treated soil from the
composting system would be placed on top of the liner. The actual design of this
distribution system needs to be inveStigated further during the remedial design to
calculate a percolation rate and ensure that the ground water is evenly distributed over
the lagoons and all areas are flushed.
After approximately twelve months, the reinfiltration of the tteated ground water would
be directed to an infiltration gallery 400 to 800 feet upgradient of the lagoons. There are
a number of different typeS of systems that could be used to provide these infiltration
areas. These include such systemS as leaching pits, fields, trenches. or galleries. For the
purpose of the FS.leaching galleries were selected; however, during the remedial
design, one of the other typeS of systemS may be selected. A leaching gallery is a 4 by 4
by 4 foot concrete box with tWO open ends and perforated sides and bottom. These
boxes are linked together into rows that provide both infiltration area and some level of
storage if there are fluctuations in the flow rate to the leaching galleries. In sizing the
leaching galleries. only the bottom area of the leaching galleries was considered even
rttI.dmt.aja.67062-62JpL617.94
-------
though there will be some infiltration through the side walls. This provides some extra
capacity for the system if the percolation rate is lower than assumed or if additional
pumping is required to meet the cleanup levels. .
Alternative 4A - 3O-year on-site treatment
Capital Cost: $300,000
Operating and Maintenance Cost: $380,000 annually
. Total Net Present Value: $6,300,000
Time for Restoration: 30 years
Alternative 4B - to-year on-site treatment
Capital Cost: ~,OOO
Operating and Maintenance Cost: $650,000 amlUally
Total Net Present Value: $5,600,000
Time for Restoration: 10 years
2.8 Summary' of Comparative Analysis of Alternatives
Nine criteria are specified by the NCP to evaluate each of the remedial alternatives. The
following is a comparison of the alternatives based on the NCP evaluation criteria.
2.8.1 protection of Human Health and the environment
Alternatives 3 (UV 1000dation Treatment) and 4 (GAC Treatment) would permanently
reduce the risks posed to human health and the environment by eliminating. reducing,
or controlling exposures to human and environmental receptorS through treatIDenL
Specifically. ~h alternative would exuact the contaminated ground water from the
aquifer and treat the water to meet performance standards. based 'on ground water
cleanup levels. During the 10- to 3O-year operating time. the contaminantS in the
aquifer would be reduced to meet the ground water cleanup levels. .
The ability to meet the time frames presented for Alternatives 3 and 4 is dependent on
tWO factOIS: (1) the ability to extraCt the contam;n3llts from the aquifer with the ground
water due to the adsorption of the contaminantS of the aquifer materials; and (2) the
ability of the alternative to effectively destroy or remove the con~minants of concern
from the ground water.
Upon achieving the ground water cleanup levels for Alternatives 3 and 4. the total
bazanI index for the ingestion of and dermal contact with ground water for all
compounds. at reasonable m!ndmum exposure, would be reduced from 30 to
approxim~te\y 2. The total incremental cancer risk for the ingestion of ground water for
all compounds, at reasonable maximum exposure, would be reduced from 3 x 10-3 to
1.3 x 1(}-5.
r=Am*67'062.Q.rpt.6f7.91
-------
Both Alternatives 3 and 4 would reinfiltrate the extracted ground water into the aquifer
to eliminate the potential for lowering the level of the water table. Reinf1ltration
galleries or reinjection wells would have to be carefully designed and located to prevent
the migration of contaminants away from the extraction wells. In addition. both of these
alternatives would include an initial discharge of treated ground water into the washout
lagoons to flush the remaining contamination from the soil. Because of the uncenainty
surrounding the flushing of the explosive contaminants from the soil into the ground
water, a detailed monitoring program would be required in order to ensure the
reinfllaation is not spreading the contamination. If the reinfiltration ca~ses an adverse
effect on the aquifer, it would be stopped and the water would be sent to the
reinflltration gallerys upgradienL
Alternative 1 (No Action) would not provide any protection of human health and the
environment and would not return the aquifer to its beneficial use in a reasonable time
frame. The implementation of the alternative would not have any beneficial impact on.
the environment.
Alternative 2 (Institutional Controls) would be protective 0f human health in that it
would resuict the access to the contaminated portion of the aquifer and would have no
adverse shon-term impacts because the contamiriated portion of the aquifer is not used.
However, as the plume continues to migrate it may impact the use of off-site ground
water when the contamination reaches the UMDA boundary.
2.8.2 Compliance with ARARs . .
Alternatives 3 and 4 would'meet the mc Health Advisories for TNT, RDX, andHMX
in the ground water in a reasonable time frame of 30 and 10 years, respectively, by
extraCting, treating and reinjecting the treateQ ground water back into the aquifer.
Alternatives 1 (No Action) and 2 (Institutional Controls) will take approximately 5,000
years to meet the preliminary remediation goals and retUII1 the ground water in the
legion to its beneficial use.
Alternative 1 does not have any action-specific ARARs because no remedial action
would be taken under these alternatives. Alternatives 2, 3, and 4 would each meet the
ARARs,.including:
.
The ground water treatment systemS for the alternatives would treat the ground
water in order to achieve the EPA Health Advisories for TNT, RDX, and HMX.
The reinfiltration of the treated ground water would meet the state surface water
discharge or underground injection regulations on the disposal of the treated
ground water.
.
.
The spent carbon from the GAC unitS would be teSted to ensure that the carbon was
not a RCRA reactive characteristic waste (explosives concentration greater than 10
percent) or a toxic characteristic waste (exceedence of the limit for 2,4-DNT in the
TCLP). If the carbon is determined to be a characteristic RCRA waste it will be
sent off site and incinerated at a RCRA-approved facility. If the carbon is not a
characteristic RCRA waste it will De treated off site at a thermal treatment facility
(e.g., incinerator, cement kiln, regeneration facility).
The metal hydroxide sludge will be tested using the TCLP to determine if the
sludge is a RCRA toxic characteristic waste. If the sludge fails the Ta..P, it will be
.
raulm..;a.61062~.4M
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.
solidified prior to disposal in a hazardous waste landfill. If the sludge passes, it will
be disposed of off site in an industrial landfill.
All facilities considered for off-site treattnent of residuals from Alternatives 3 and 4
would meet the NCP Procedures for Planning and Implementing Off-Sire Response
Actions as presented in the September 22, 1993 Federal Register, 58 FR49200.
RCRA listed waste categories K045 and K047 are not appropriate for three reasons:
(1) they are not from the manufacture of explosives, (2) they are below the waste
characteristics level for which K045 and K047 were listed (reactivity), and (3) they
result from the treattnent of ground water instead of wastewater. Specifically, K045
covers spent carbon from the treatment of explosives-contaminated wastewaterS (40
CFR ~ 261.32). The extraCted ground water is not considered a wastewater and
therefore the caibon generated in either Alternative 3 or 4 would not be considered a.
K045 waste. As indicated above. the carbon would be considered a RCRA reactive
characteristic waste (40 CFR ~ 261.23) if the explosive concentration on the carbon
exceeded 10 percent or a toxicity characteristic RCRA waste (40 CFR ~ 261.24) :<: a
TCLP analysis indicateS a 2.4-DNT concentration equal to or greater than 0.13 rr.yL.
The RCRA waste category K047 is not relevant to the ground water because it applies
to wastes generated dming the production and fmmulation of TNT and TNT -containing
products (40 CFR ~ 261.32). The operations at the Explosives Washout Plant did not
involve the manufactore,loading. or packing of explosives, nor the production and
formulation of TNT compounds. Therefore. the wastes from the Explosive Washout
Plant including the contam;nated .ground water do not meet the definition of listed
wastes and the RCRA requirements, then-fore. are not legally applicable.
2.8.3 Long-Term Effectiveness
Alternatives 3 and 4 would reduce the contamination in the ground water to below
ground water cleanup levels in a time frame of either 30 (3A and 4A) or 10 (3B and
4B) years. The ability to meet the time frames presented in these alternatives is
dependent on two factm'S: (1) the effect that the contaminants adsorbed onto the aquifer
materials has on the ability to extraCt the conVlm;nants from the aquifer with the ground
water; and (2) the ability of the alternative to effectively destroy or remove the
conum;n~ts of concern from the ground water. .
Upon achieving the remedial action objectives for Alternatives 3 and 4, the total hazard
index for the ingestion of and dermal contact with ground water for all compounds. at
reasonable mn;mum exposure, would be reduced from 30 to less than 2; and the total
incmnental cancer risk for the ingestion of ground water for all compounds at
reasonable m"rimum exposure would be reduced from 3 x 10-3 to 1.3 x 10-5. The
reduction in the risks would meet the NCP req~nt for excess risk. In all cases. the
remaining risks would be due to the rerna;ning explosive contamination.
Alternatives 1 3nd 2 would provide almost no long-term effectiveness because the
conVlnnnantS would continue to migrate toward the UMDA boundary.
Alternatives 3 and 4 would produce treatment residuals that would have to be treated
and disposed of off site. All residuals generated during the remediation of the ground
water would be disposed of in a manner to eliminate unacceptable risks.
rd).dmI~6i7.9'
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.
Alternative 3 would generate tWO types of treatment residuals, metal hydroxide
sludge and spent carbon loaded with explosives and their degradation compounds.
Over the life of the remediation an estimated 4,400 to 5,300 tons of metal
hydroxide sludge would be produced and 55 to 70 tons of explosives-contaminated
carbon would be generated.
Unlike Alternative 3, Alternative 4 would only generate one type of treattnent
residual. spent carbon loaded with explosives and their degradation compounds.'
Over the life of the remediation an estimated 570 to 680 tons of explosives-
contaminated carbon would be generated.
.
The metal hydroxide sludge from the metal precipitation unit would be tested using the
TCLP method to determine if it was a RCRA hazardous waste. If the sludge failed the
TCLP teSt. it would be sent off-site for solidification prior to be disposed of in a .
landfill. If the sludge passed the TCLP it would be disposed of in an industrial waste
landfill.
The spent carbon from the GAC units would be tested to ensure that the carbon was not
either a RCRA reactive characte1:istic waste (explosives ~ncentration greater than 10
percent) or a toxic characteristic waste (exceedence of the limit for 2,4-DNT in the
TCLP). If the carbon is determined to be a characteristic RCRA waste it will be sent
off-site and thermally treated at a RCRA approved facility. If the carbon is not a
characteristic RCRA waste it will be treated off site at a thermal treatment facility (e.g.,
incinerator, cement kiln, regeneration facility).
All four alternatives would require five-Yf3r reviews to evaluate whether the alternative
remains protective of public health and the environment The five-year reviews would
be initiated five years after the stan of the remedial action and would continue only
until the cleanup levels are met. since these levels allow for unrestticted use of the
aquifer. .
2.8.4 ReducUon of Toxicity, Mobility, or Volume through Treatment
Alternatives 1 and 2 would allow the contaminated region to naturally attenuate. The
natmal attenuation would not reduce the toxicity, mobility, or volume of the
contamination ,by treatment; however, the reduction of the cont1lmination would occur
by natUral means (biological, abiotic, and diffusion) over a 5,OOO-year period. During .
this period the contaminants would continue to migrate towards the UMDA boundary,
and the RDX plume is estimated to reach the boundary in 70 years at a concentration
that would pose an incremental carcinogenic risk of 1 x IG-6.
In Alternative 3, the UV loxidation system would remove approximately 90 percent of
the contamination from the extracted ground water, based on pilot-scale treatability
studies cited in the FS and an economic analysis. The remaining contaminants would be
adsorbed using the GAC polishing system.
The UV loxidation system would irreversibly destroy the contaminants direcdy by .
o,ridi7'ing the organics to carbon dioxide, water, and nitrateS. The residual contaminants
woukl adsorb onto the GAC. The contamination adsorbed on the GAC would then be
irreversibly destroyed by thermal treatment at an off-site facility.
In Alternative 4, the primary GAC treatment system would remove greater than 99
percent of the contamination from the extracted ground water, based on previously
=.dIft.$.S7062~$4
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conducted adsorption studies cited in the FS. The adsorbed contaminants would be
irreversibly destroyed when the spent GAC is incinerated or treated using another type
of thermal treatment such as regeneration or a cement kiln.
2.8.5 Short-Term Effectiveness
The operations of Alternatives 3 and 4 are not expected to increase the risk to the
community since no contaminants will be released to the environment. The risks to the
workers and environment from using the acids, bases. and the ozone would be
minimized through the use of engineering controls and personal protective equipmenL
Alternatives 3 and 4 will achieve long-term effectiveness in the ground water in the .
reasonable time frame of 30 and 10 years, by extraeting, treating and reinjecting the
treated ground water back intO the aquifer. Alternatives 1 and 2 would take
approximately 5,000 years to meet the long-term objective of retUITring the ground.
water in the region to its beneficial use.
Alternatives 3 and . ~ would produce treatment residuals that would have to tTP.at~ and
disposed of off site. All residuals generated during the n-mediation of the ground water
would be disposed of in a manner to eliminate unacceptable risks.
.
Alternative 3 would generate tWo types of treatment residuals. metal hydroxide
sludge and spent carbon loaded with explosives and their degradation compounds.
Over the life of the remediation an eStimllteil 4,400 to 5.300 tons of metal
hydrOxide sludge would be produced and 55 to 70 tons of explosives-contaminated
carbon would be generated. ..
Unlike Alternative 3. Alternative 4 would only generate one type of treaUDent
residual. spent carbon loaded with explosives and their degradation compounds.
Over the life of the remediation an estimllteil 570 to 680 tons of explosive
contaminated carbon would be generated.
.
The metal hydroxide sludge from the metal precipitation unit would be tested using the.
Ta.2 method to determine if it was a RCRA hazardous waste. If the sludge failed the
Ta.2 teSt, it would be sent off site for solidification prior to be disposed of in a
landfill. If the sludge passed the TCLP it would be disposed of in an industrial waste
landfill.
The spent carbon from the GAC units would be tested to ensure that the carbon was not
either a RCRA reactive characteristic waste (explosives concentration greater than 10
percent) or a toxic characteristic waste (exceedence of the limit for 2,4-DNT in the
TC1P). If the carbon is determined to be a characteristic RCRA waste it will be sent
off-site and thermally treated at a RCRA approved facility. H the caIbon is not a
characteristic RCRA waste it will be treated off site at a thermal treatment facility (e.g.,
incineratOr. cement kiln. regeneration facility).
2.8.6 Implementation
All of the technologies that would be used in these alternatives are considered reliable.
However, the UV loxidation pilot StUdy for Milan Army Ammunition Plant cited in the
FS found that UV loxidation could not economiCally meet cleanup levels without GAC
being used as a polishing uniL
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The construction and operation of the UV loxidation system for Alternative 3 can be
implemented with few concerns and is technically capable of treating the contaminants
in the ground water. The specific concerns regarding UV/oxidation are (1) the fact that
UV/oxidation has never been used on a full-scale for the treattnent of explosives-
contaminated ground water, and (2) the maintenance ofUV systems is known to be
high, especially with regard to the fouling of quartz light tubes and the changing of the
UV lamps.
The construction and operation of the GAC system for Alternative 4 would be easier
than the UV loxidation system. GAC systems are commonly used at Army facilities for
the treatment of wastewaterS containing explosives and have been found to be highly
reliable. Therefore,unlike UV loxidation there are substantial full-scale operating data
.for GAC systems. .
The processing capacitV of both Alternatives 3 and 4 can be increased if additional
ground water nee :.; ~ be treated or the concentration of contamination is greater than
expected. No special equipment, materials, or technical specialists would be required
for the implementation of these remedial alternatives.
Alternatives 3 and 4 would require state and local coordination for the implementation
of legal restrictions on the use of ground water at the site. .
2.8.7 Cost
The capital and operating costs for each alternative are shown below:
Alternative Capital Cost operating Cost Total NPV
1 $4.000 $81,000 (a)
2 $20.000 $40.000 $820.000 (a)
3A $2,200.000 $790.000 $14.700.000 (b)
3B $3.700.000 $1.600.000 $16.300.000 (c)
4A $400.000 $380.000 $6.400,000 (b)
4B $550.000 $670,000 $5,800.000 (c)
(a) Total NPV es&ima1ed over sooo years at an intereSt rate of 5%
(b) Total NPv. ~MM o'Jer 30 years at an intereSt rate of 5%.
(c) Total NPV esV-MM over 10 years at an inu:n:st rate of 5%.
2.8.8 State AccePtance
The Sta~ of Oregon has reviewed and approved this document and the proposed
al1eD1&tlve.
2.8.9 Public Acceptance
The absence of any negative comments from the public has been taken as acceptance of
the proposed altem8tive. .
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2.9 Selected Remedy
The selected remedy to clean up the soil contamination associated with the UMDA
Explosives Washout Lagoons, Ground Water Operable Unit is Alternative 4B. lO-year
on-site treatment using GAC treatment followed by reinfiltration of the treated ground
water. This alternative was selected because it is protective, feasible. and cost-effective.
Alternative 4B was selected over the other alternatives because it actively remediates
the contaminated ground water in a time frame that is equal to or better than the other
alternatives at a cost that is less than the other active remedial alternatives.
The estimated net present value of Alternative 4B is estimated to be $5.800.000. GAC
treatment is a well established. proven teChnology for ground water. Even though this
remediation step does not provi4e for the immediate destruction of the contaminantS,
off-site treatment through thermal destruction will be provided. An estimated 1.75
billion gallons of water would be treated with this remediation option. .
The major componf"n~s of the alternative are:
.
Extraetion of the ground water from an estirruUed three extraCtion wells over an
estimated l~ to 3O-year period
Treatment by GAC to meet performance standards based on the ground water
cleanup levels
.
.
In-situ flushing of subsurface soils beneath the lagoons with all or pan of the
treated ground water for an estimated period of one year
Upgradient reinjeCtion of the treated ground water that does not go to the
Explosives Washout Lagoons and all the treated water after the in-situ soil flushing
is completed .
.
.
Testing of the spent GAC to determine RCRA characteristic hazardous waste status
Off-site thermal treatment and disposal of explosive contaminated GAC to the level
specified in the remedial design (off-site thermal treatment will be in compliance
with the EPA Off Site Rule) . .
.
.
Monitoring of ground water contamination to determine the effectiv.eness of the
remedial action and to determine when the ground water cleanup levels have been
attained . .
Institutional connols on the contaminated ground water to prevent the use of the
ground water until ground water cleanup lev~ls are met
The remediation of the ground water will continue until the concentration of explosives
in the aquifer meetS cleanup levels that are proteetive of human health and the'
. environmenL Because no ARARs cmrently exist for the explosive contaminantS. risk-
based cleanup levels were calculated to proteCt against carcinogenic risks in excess of 1
x IG-6 and non-carcinogenic risks with a hazard quotient greater than 1. Lifetime
Human Health Advisories were considered TBC criteria and were also used to set
cleanup levels. The performance standards for the treatment of the extraCted ground
water were set in the same manner as the cleanup levels for the aquifer.
.
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A limit of 10 percent explosives on the GAC sent off site was set in order to ensure that
the GAC would not bea characteristic RCRA hazardous waste for reactivity. The 10
percent limit was set based on a USAEC study (Arthur D. Little, 1987) to determine
reactivity of explosives-contaminated sludges. The spent GAC would also have to pass
a Ta..P test for 2,4-DNT in order not to be considered a RCRA hazardous waste. The
actUal performance standards for the off-site thermal treatment of the explosives-
contaminated GAC would be detennined during the remedial design; however they
would be based on either a residence time and temperature or a chemical-specific
cleanup level for the residuals that are below risk-based remedial action criteria.
In order to ensure that the off-site thermal treatment does not contribute to present or
future environmental problems, the selection of a thenna1 treatment facility will follow
the procedures presented in Procedure$ for Planning and Implementing Off-Site
Response Actions, 58 FR 49200, September 22, 1993. .
The goal of this remedial action is to restore the ground water to its potential benef.:ial
use, which may include drinking water or non-domestic uses. Based on the iruormation
obtained during the RI, and the analysis of all remedial alternatives, the Army, EP A,
and the State of Oregon believe that the selected remedy may be able to achieve this
goal. Ground water contamination may be especially persistent in the immediate
vicinity of the contaminants' source, where the concentrations are relatively high. The
ability to achieve cleanup levels at all points throughout the area of auainment, or
plume, cannot be determined until the extraction system has been implemented,
modified as necessary. and plume response monitored over time. .
The selected remedy will include ground water extn.Ction for an estinultf'.d period of 10
to 30 years, during which time the system's performance will be carefully monitored on .
a regular basis and adjusted as wananted by the performance data collected during
operation. Modifications may include any or all of the following:
.
Discontinuing pumping at individual wells where cleanup levels have been attained
Alternating pumping at wells to eliminate stagnation points
.
.
Pulse pumping to allow aquifer equilibration and encourage adsorbed contaminants
to partition into the ground water
Installation of additional extraction wells to facilitate or accelerate cleanup of the
contaminant plume .
.
To ensure that cleanup levels continue to be maintained, the aquifer will be monitored
at least annually at those wells where pumping bas ceased.
2.10
Statutory Determinations
The re~;al action selected for implementation for the Explosives Washout Lagoons
Ground Water Operable Unit is consistent with CERCLA and, to the extent practicable,
the NCP. The selected remedy is proteetive of human health and the environment,
attains ARARs and is cost-effective. The selected remedy also satisfies the statutory
preference for treatment that permanently and significantly reduces the mobility,
toxicity, or volume of h~oUS substances as a principal element. Additionally, the
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selected remedy utilizes alternate treaunent technologies or resource recovery
technologies to the maximum extent practicable.
2.10.1 Protection of Human Health and the Environment
The remedy at this site will pennanently reduce the risks posed to human health and the
environment by eliminating, reducing, or controlling exposures to human and
environmental receptors through treatment, engineering controls, and institUtiQnal
contrOls. Specifically, Alternative 4B would extract the ground water from the aquifer
and treat the contaminated ground water using a GAC system. The perfonnance
standards for the GAC system would be equivalent to the cleanup levels selected for the
aquifer. The treated ground water would be allowed to reinfiltrate into the aquifer. The
extraCtion of the ground water would also min;m;7,e the migration of the contaminants,
. and institUtional controls would restrict the use of the aq~erwhile the remedial action
was being conducted . . ..
Moreover, the selected remedy will achieve potential human health risk levels that
attain the 1 x 1 ()4 to 1 x 1 G-6 incremental cancer risk range and a level protective of
non-carcinogenic endpoints, and will comply with. ARARs a.'1d TBC criter -.. Upon
achieving the remedial action objectives, the total hazard index for the ingestion of
ground water for all compounds, at reasonable maximum exposure, would be reduced
from 30 to 2. The total incremental cancer risk for the ingestion of ground water for all
compounds at reasonable maximum exposure would be reduced from 3 x 10-3 to 1.3 x
l()-s (see Section 2.6, Snmmary of Site Risks).
When ground water cleanup levels identified in this ROD and newly promulgated .
ARARs and modified ARARs, bave been acbieved and bave not been exceeded for a
period of three consecutive years, the remedy will be considered complete.
2.10.2 Compliance with ARARs
This remedy will attain all applicable or relevant and appropriate federal and state
n:quirements that apply to the site. Environmental laws from which ARARs for the
selected remedial action are derived and the specific ARARs include:
.
Resource Conservation and Recovery Act
Oregon Hazanious Substance Remedial Action Rules
Oregon Underground Injection Regulations .
Oregon Water Resources Adminimation and Appropriation Acts (ORS Chapters
536 and 537) .
Oregon Water Supply Well Construction and Maintenance Regulations (OAR
Olapter 690, Division 200) .
Oregon Water Quality. StatUteS for Ground Water (ORS Chapter 468B.15O. through
468B.185)
.
.
.
.
.
In addition to these.'ARARs the EPA's Health Advisories are considered as TBC
criteria. . . .
2.10.2.1 ResOurce Conservation and Recovery Act RCRA is applicable to the
spent carbon that is generated dming the treatment of the ground water at the site if the
carbon is found to be a RCRA reactive characteristic waste or a toxic characteristic
waste. Specifically, The spent carbon will be tested to determine if the explosives
contamination exceeds 10 percent, which is the limit for the carbon to be considered a
RCRA reactive characteristic waste. A TCLP analysis will also be performed on the
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spent carbon to detennine if the 2,4-DNT concentration exceeds 0.13 mgIL in the
TQ..P extract, which is the limit for a RCRA toxic characteristic waste. If the spent.
carbon is found to be a characteristic waste then it will be managed as a RCRA waste
and sent off-sire to a RCRA-approved thermal treatment facility (e.g., incinerator,
cement kiln, regeneration facility).
RCRA listed waste categories K045 and K047 are not considered ARARs for the
remediation of ground water at the washout lagoons because they are not relevant.
Specifically, K045 CQvers spent carbon from the treatment of explosives-contaminated
wastewaters (40 CFR ~ 261.32). The extracted ground water is not considered a
wastewater and therefore the carbon generated in either Alternatives 3 or 4 would not
be considered a K045 waste. As indicated above, the carbon would be considered a
RCRA reactive characteristic waste (40 CPR ~ 261.23) if the explosives concentration
on the carbon exceeded 10 percent or a toxicity. characteristic RCRA waste (40 CFR ~
261.24) if a TCLP analysis has 2,4-DNT concentration equal to or greater than 0.13
mg/L.
The RCRA waste category K047 is not relevant to the ground water because it applies
to wastes generated during the production and formulation of TNT and TNT -containing
products (40 CFR i 261.32). The operations at the Explosives Washout Plant did not
involve the manufactUre, loading, or packing of explosives, nor the production and
formulation of TNT compounds. Therefore, the wasteS from the Explosive Washout
Plant including the contaminated ground water do not meet the definition of listed
wasteS and theRCRA requirements and, therefore, are not legally applicable.
2.10.2.2 Oregon HIIzlIrdous SUbStBnCe Remedial Actlon Rules. The Oregon
Hazardous Substanee Remedial Action Rules is an applicable regulation for the ground
water at the Explosives Washout Lagoons. The Act provides a process for determining
contaminant cleanup levels on a site-specific basis. The process is implemented as
follows:
.
In the event of a release of a hazardous substance, the environment shall be restored
to background level (Le., the concentration naturally occurring prior to any release
from the facility) [OAR 340-122-04O(2)(a)].
When attaining background level is not feasible, the acceptable cleanup level in .
ground water shall be the lowest concentration level that satisfies both the
"proteetion" and "feasibility" requirements in OAR 34().l22-09O(I)/nte party
responsible for the contaminated 'site is responsible for demonsuating the non-
feasibility of auaining background level.
.
Of the seven explosives contaminants of concern in the Explosives Washout Lagoon
Ground Water Operable Unit, none are considered to be natmally occurring. Therefore,
;the background concentration would be essentially zero or, for practical purposes,
below deteCtion limits. " . .
"
The cleanup levels for the explosives, 2,4-DNT, 2,6-DNT. and RDX, are set at
deteetion limits and will therefore meet the intent of the regulation. The cleanup levels
for TNB, DNB. TNT. and HMX are set above their deteCtion limits. The cleanup levels
for TNB. DNB. and TNT were set at a level that was proteCtive of human health based
on achieving a non-caICinogenic hazard quotient of 1 for each and an excess
carcinogenic risk of 1 x 1~. The cleanup level for HMX was set based on the EP A
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health advisory for HMX which is 350 J.Lg/L. The health advisory is set based on the
protection of human health over a lifetime and is therefore considered to meet the
requirements of the regulation. Since the cleanup levels set above background will
achieve risk-based goals. the additional effon to reach background is not considered
cost-effective.
2.10.2.3 Oregon Underground InJectlDn. OAR Chapter 340. Division 44 is also an
applicable state ARAR specific to the reinfiltration of treated ground water back into
the aquifer. These regulations will influence the location. construction, and use of any
underground injection wells so as to prevent contamination of the underground sources
of drinking water. Specifically, OAR 34044-0l5(4)(d) specifies that underground
injection activities that allow the movement of fluids into an undergrounci source of
drinking water (e.g.. the ground water at Site 4) may not violate any SDW A MQ..s.
The explosives in the ground water do not currently have SDW A MCLs; therefore.
remediation of these compounds to levels that are proteCtive of human health and the
environment would meet the intent of the regulation. Nitrates were found in the ground
water at UMDA at a level above the MCL of 10 mg/L. The source of the nitrate; s not
UMDA but off-site agricultural activities. The selected remedy would not treat the
ground water to meet the MCL for nitrate because it is considered to be an off-site
contaminanL While this does not meet the requirement of the regulation, ODEQ has
agreed to waive the tequUement for compliance with the MCL specific to nitrate if the
treated ground water is reinfiltrated within the capture zone of the ground water
extraetion wells. Both the discharge to the lagoons and the upgradient reinfiltration
galleries will, therefore. be designed to be within the capture zone of the extraction
wells.
2.10.2.4 Health Advisories. EPA Health Advisories were considered as TBC criteria .
when setting ground water cleanup levels for RDX, TNT, and HMX. The other four
explosives did not have health advisories. The health advisories were obtained from the
December 1993 Drinking Water Standards. The health advisories were compared to the
calculated risk-based cleanup levels and where the health advisories were significantly
lower than the risk-based cleanup level the health advisory was used as the ground
water cleanup level. The health advisories for both RDX and TNT were higher than the
risk-based cleanup levels. The HMX health advisory was lower than the risk-based
cleanup level; therefore, the ground water cleanup level for HMX was set at the health
advisory level.
2.10.3 Cost .
In the judgment of the Army and EPA. the selected remedy is cost-effective, ie., the
remedy affords overall effectiveness proportional to its COStS. In selecting this remedy,
once the Army and EP A identified alternatives that are protective of human health and
the environment and that attain or. as appropriate, waive ARARs, the Army evaluated
the overall effectiveness of each alternative by assessing the relevant three criteria -
long-term effectiveness and permanence; reduction in toxicity. ~bility. and volume
through treaID1CI1t; and short-term effectiveness, in combinatiOn. The relationship of the
overa1l effectiveness of this remedial alternative was determined to be proportional to
its costs.
Both Alternatives 3 and 4 would be effective in remediating the site. Alternatives 3A
and 3B would meet the remedial action objectives at a cost of $14.7 million and $16.3
million., respectively. Both Alternatives 4A and 4B will meet the remedial action.
r=.dII'I.aja.S7062~
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objectives for approximately half the cost of Alternatives 3A and 3B. In addition,
Alternative 4B will meet the ground water cleanup levels approximately 20 years
earlier and at a cost of $0.7 million less than 4A. Therefore. Alternative 4B, at a cost of
$5.6 million, will provide the most cost-effective remedy.
2. 10.4 Utilization 01 Permanent Solutions and Alternative Treatment
Technologies or Resource Recovery Technologies to the Maximum
Extent Practicable
Based on cwrent information and analysis of the RI and FS reportS. the Army and EPA
believe that the selected alternative (Alternative 4B) for the Explosives Washout
Lagoons site is consistent with the requirements of CERCLA and its amendments,
~~cally Section 121 ofCERaA. and the NCP.
The selected alternative provides overall protecrlon of huuian health arid the
environment and achieves the risk-based cleanup levels by permanently removing the
contamination from the aquifer and destroying it in a thermal treatment facility. The
preferred alternative provides for the significant reduction of toxicity, mobi1;ty, OtuJ
volume through coi1Wnment and treatmenL The preferred alternative also poses the
fewest short-term risks. achieves cleanup in the shortest practical time, and is the most
cost effective. .
If feasible the selected alternative would regenerate the explosives-laden carbon for
reuse at UMDA or send the explosives-laden carbon to a cement kiln, where the
energetic content of the material would be recovered. By using either of these thermal
treatment options the selected alternative would be utilizing a resomce recovery
technology. In addition, both of these thenna! treatIIlCnt processes are considered
innovative.
In snmma1')', the preferred alternative would achieve the best balance among the criteria
used by EPA to evaluate the alternatives, including:
.
Provide short- and long-term protection of human health and the environment
Attain all risk-based cleanup levels
.
.
Provide significant reduction of toxicity. mobility. and volume of the site
contaminants through treatment
.
Utilize permanent solutions and innovative treatment technologies to the maximum
extent practicable .
The support of the state and community in the evaluation process and the selection of
Alternative 4B further justify the selection of Alternative 4B.
The selected remedy meets the statutory requirement to utilize permanent solutions and
alternative treatment technologies to the maximum extent practicable.
2.10.5 Preference for Treatment as a PrIncipal Element
The principal element of the selected remedy is the adsorption of the con~minants from
the ground water using carbon adsorption followed by off-site thenna! treatment of the
spent carbon to destroy the explosive contaminants. The selected remedy, through the
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use of carbon adsorption and off-site thennal treatment, satisfies EPA's preference for
treatment that pennanently and significantly reduces the toxicity, mobility, or volume
of the hazardous substance.
2.11
Documentation 01 No Significant Changes
The Army and EPA presented a proposed plan (preferred alternative) for remediation of
the Explosives Washout Lagoon Ground Water Operable Unit on March 2, 1994 during
a public meeting. The proposed alternative presented in the proposed plan is the same
as the selected alternative, Alternative 4B, presented in this ROD. No significant
changes were made to the proposed alternative as a result of the public comment and
public meeting.
~~
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3.0 Responsiveness Summary
The final component of the ROD is the Responsiveness Summary, which serves tWo
purposes. First, it provides the agency decision makers with infonnation about
community preferences regarding the remedial alternatives and general concerns about
the site. Second, it demonstrates to members of the public how their comments were
taken into account as part of the decision-making process.
Historically, community interest in the UMDA installation has centered on the impacts
of installation operations on the local economy. Interest in the environmental impacts of
UMDA activities has typically been low. Only the proposed chemical demilitarization
program. which is sep~rate from CERCLA remediation programs. has drawn
substantial comment and concern.
As pan of the installation's community relations program. UMDA assembled in 1988 a
TRC composed of elected and appOinted officials and other interested citizens from the
sunounding communities. Quanerly meetings provide an opponunity for UMDA to
brief the TRC on installation environmental restoration projects and to solicit input
from the TRC. Two TRC meetings were held during preparation of the feasir;lirv SlUCj'
for the Explosives Washout Lagoons Ground Water Operable Unit. In those meetings,
the TRC was briefed on the scope and results of the supplemental investigation and the
methodology of and remedial alternatives considered in the feasibility study.
In December 1993. the TRC was expanded to meet the requirements of the RAB based
on DaD guidance. Two RAB meetings were held during the selection of the proposed
alternative.
The feasibility study and proposed plan for the Explosives Washout LagoonS Ground
Water Operable Unit were made availat.'~ to the public on February 15. 1994 at the
following locations: UMDA Building 32. Hermiston, Oregon; the Hermiston Public
Library, Hermiston. Oregon; and the EP A offices in Portland, Oregon. The notice of
availability of the proposed plan was published in the Hermiston Herald, the Tri-Ciry
Herald, and the East Oregonian on February 15. 1994. The public comment period
ended on Much 17, 1994.
A public meeting was held at the Armand Larive Junior High School, Hermiston.
Oregon, on Much 2, 1994, to inform the public of the preferred alternative and to seek
public comments. At this meeting. representatives from UMDA, USAEC. EPA, ODEQ,
and Arthur D. Little represented the proposed remedy. Approximately six persons from
the public and media attended the meeting. No questions were asked during the
informal question and answer period specific to the Explosives Washout Lagoons
Ground Water Operable Unit.
Two written comments were received during the comment period and expressed
concern about the incineration of explosives and weapons on-site at UMDA. The
comments were not addressed to a specific operable unit. Proposed plans for five
operable units were presented during the comment period and these comments appear
to relate specifically to the Explosive Washout Plant Operable Unit, since the proposed
remedy would thermally oxidize the explosive contaminants in an afterburner. The
comments are addressed in the Explosive Washout Plant ROD.
These comments could also be related to a misunderstanding about the treatment of the
spent carbon from the treatm~nt of the ground water. This carbon will contain
expl~ves and will be shipped off site for thermal treatment. No incineration of the
rcb.dmI~&71M
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carbon will be perfonned on site at UMDA. Off-site thermal treatment of the carbon
would be perfonned at an EPA-approved incinerator, cement kiln, or carbon
regeneration facility. The thennal destruction of the explosives would completely
oxidize the explosives to carbon dioxide, water, and nitrous oxides. In all cases the
thermal treattDent of the spent carbon would be protective of human health and the
environment.
rdI.dnf~11M
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Appendix A
Oregon DEQ Letter of Concurrence
.
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Chuck Clarke
Page 2
If you have any questions concerning this matter, please contact Bill Dana of DEQ's Waste
Management and Cleanup Division at (503) 229-6530.
Sincerely,
~~~
Fred Hansen
Director
BD:m
SITE\SM5937
cc: Lewis D. Walker. DOl")
LTC. Moses W.,itehurst, Jr., UMDA
Harry Craig. EPA-OOO
Jeff r:todin, EPA. Seattle
Bill Dana. DEQJWMCD
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Appendix B
Documents Supporting the Ground Water ROD
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The following documents outline the results of the site investigations and assessments
of cleanup actions for the Explosives Washout Lagoons Ground Water:
t'
Arthur D. Little, Inc. 1993. Final Feasibility Study for Ground Water at Explosives
Washout Lagoons Activity Area (OU3) at the UmatilLa Depot Activity (UMDA).
Prepared for U.S. Army Environmental Center, Contract DAAA15-91-D-0016,
Delivery Order No.2. December.
Arthur D. Little, Inc. 1987. Testing to Determine Relationship BetWeen Explosive
Contaminated Sludge ComponentS and Reactivity. Prepared for the U.S. Army Toxic
and Hazardous Materials Agency. ContraCt No. DAAK 11-85-D-0008, Repon No.
AMXTH-TE-CR-89096.
CH2M HlLLlMorrison. 1992. Knudsen Environmental SeMCes. FeaSibility Study for
the Explosives Washout Lagoons (Site 4) Soils Operable Unit Umatilla Depot Aciivity
(UMDA), Hermisron, OreRon. Prepared for the U.S. Army Toxic and Hazardous
Materials Agency. r:pon No. CEmA-BC-CR-92(J17.
Dames & Moore, Inc. 1994. Draft Treatability Test Rep.:;rt for the Contaminated
Groundwater at the Umatilla Army Depot Activity, Henniston, Oregon, Prepared for
the U.S. Army Environmental Center. ContraCt No. DAAAI5-88-D-0008.
Dames & Moore, Inc. 1992a. Final Remedial Investigation Reportjor the umDtilla
Depot Activity Hermisron, Oregon. Volumes 1 through 6. Prepared for the U.S. Army
Toxic and Hazardous Materials Agency. Contract No. DAAA15-88-D-0008, Delivery
Order No.3. . .
Dames & Moore, Inc. 1992b. Final Human Health Baseline Risk Assessment UmarilLa
Depot Activity Hermisron, Oregon. Prepared for U.S. Army Toxic and Hazardous
Materials Agency. ContraCt No. DAAA 15-88-D-0008, Delivery Order No.3.
T
rc:D.1ftf.aja.67'062-Q.ipL6/7.94
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