United States Office of
Environmental Protection Emergency and
Agency Remedial Response
EPA/ROD/R10-92/051
September 1992
&EPA Superfund
Record of Decision
UmatillaArmy Depot
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.;.
NOTICE
The appendices listed in the index that are not found in this document have been removed at the request of
the issuing agency. They contain material which supplement. but adds no further appilcable information to
. the content of the document. All supplemental material is, however, contained in the administrative record
for this site.
.~~,: ... .~ ~ ~, 7 ,", '..-
. .
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50272-101
REPORT DOCUMENT A TJON 11. REPORT NO. I ~ 3.. A8c:ipI8nI'8 ~ No.
- PAGE EPA/ROD/R10-92/051
4- 11Ie 8nd SUbft8 I. AIpor1 D88It
SUPERFUND RECORD OF DECISION 09/25/92
Umatilla Army Depot (Lagoons), OR
..
First Remedial Action - Subsequent to follow
r. AuIhor(8) .. Pwt:..mkl8 Orpnba1lGft A8pt. No'
8. PwrfonnIng 0r;8InIzd0n ..... ... Add!-. 10. fIrot8dIT88IIIWort lINt No.
11. ConIrIId(C) or Glwll(G) No.
Ic)
IG)
,~ Spon8orIng 0rg8nIzaII0n ..... ... Add!-. 13.. Type of R8p0rt. PwItocI CoWW8d
U.S. Environmental Protection Agency 800/000
401 MStreet, S.W.
Washington, D ..C. 20460 ..J4-
,1. ... H' ....-r No...
PB93-964610
,.. Ab8nd (UinIt: 2110 WOftIa)
The Umatilla Army Depot lagoons site is located in the center of the
19,700-acre U.S. Army Depot Activity, Umatilla (UMDA), 5 miles west of Herrniston, in
Morrow and Umatilla Counties, Oregon. This installation was established in 1941 as an
Army Ordnance Depot to store and handle munitions. Land use in the surrounding area is
primarily agricultural. 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 also draw from ground water within that same radius.
From the 1950's through 1965, UMDA operated an onsite explosives washout plant, which
processed munitions to remove and recover explosives using a pressurized hot water
system. Pl-ant operations- included flushing and draining the explosives washout system,
and wash water was discharged via an open metal trough to two infiltration lagoons,
known as the explosive washout lagoons, located to the northwest of the plant. The
lagoons were constructed in the 1950s and utilized until 1965, when plant operations
and all discharges- to the lagoon ceased. An estimated 85,000,000 gallons of efflu,ent
were discharged to the lagoons during plant operations. Investigations performed by
the Army in the late 1970s to evaluate past use, storage, treatment, and disposal of
(See Attached Page)
17. ~....,. .. 0-- ~
Record of Decision - Umatilla Army Depot (Lagoons), OR
First Remedial Action - Subsequent to follow
Contaminated Medium: soil
Key Contaminants: Inorganics, explosives (DNB, 2,4 DNT, HMX, NB, TNB, TNT, RDX)
b.~T-
Co COSATI FWdIGroup
,.. AVIiI8IIiIty..... ,8. s.a.tty a- (ThI8 AIpor1) 21. No. of""
None 50-
211. s.a.tty ClaM (ThI8 Page) Z2. PrIce
. None
14oT1)
ISee AJS.Z38.18)
s.. butrucfI- on ~--
(Fon8ty IfTIS.35)
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EPA/ROD/R10-92/051
.Umatilla Army Depot (Lagoons), OR
First Remedial Action - Subsequent
Abstract (Continued)
to follow
toxic materials, revealed"contamination in the soil and shallow aquifer beneath the
lagoons. The facility has been divided into 8 operable units for remediation. This ROD
provides a final remed~ for the soil present at the lagoons. A future ROD will address
contaminated ground water beneath the lagoons and 6 remaining RODs will address remaining
portions of the UMDA installation. The primary contaminants of concern affecting the
soil are inorganics and explosives, including DNB, 2, 4-DNT, HMX, NB, TNB, TNT, and RDX.
. The selected remedial action for this site includes developing a composting facility
onsite; constructing a roadway between the lagoons and the onsite composting facility to
transport the excavated and treated soil; excavating to a 5-foot depth, approximately
6,800 tons of contaminated soil with concentrations of TNT or RDX exceeding 30 mg/kg;
treating the soil onsite using ex-situ bioremedlation via composting; backfilling the
excavated lagoon areas with the compost, then covering the compost with a 2-foot layer of
clean soil and grading and revegetating the area. The estimated present worth cost for
this remedial action is $1,870,000, which includes an estimated total O&M cost of
$1,084,000 over 2 years.
PERFORMANCE STANDARDS OR GOALS: Chemical-specific~excavation goals for soil are based on
risk-based remedial action criteria (RAC) and include TNT 30 mg/kg (RAC) and RDX 30 mg/kg
(RAC). These levels correspond to an,excess cancer risk under the industrial use
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u. S. ARMY INSTALLATION
RESTORATION PROGRAM .
RECORD OF DECISION
A.lttt ¥
UMA~EPOT AcrIVITY
EXPLOSIVES 'WASHOUT LAGOONS
SOILS OPERABLE UNIT ~. } (] ~
September 1992
In accordance with Army Regulation 200-2, this document is intended by the Army to
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TABLE OF CONTENTS
ACRONYMS AND ABBREVIATIONS v
1.0 DECLARATION OF TIIE RECORD OF DECISION 1
Site Name and Location 1
Statement of Basis and Purpose 1
Assessment of the Site 1
Description of the Selected Remedy 1
Statutory Determinations 2
Lead and Support Agency Acceptance of the Record of
Decision . -- 3
~-
2.0 DECISION SUMMARY 7
2.1 Site Name, Location, and Description 7
2.2 Site History and Enforcement Activities 10
2.3 Highlights of Community Participation 12
2.4 Scope and Role of Operable Unit 13
2.5 Site Characteristics 13
2.6 Summary of Site Risks 17
2.7 Description of Alternatives 24
2.8 Summary of Comparative Analysis of Alternatives 31
2.9 Selected Remedy 36
2.10 Statutory Determinations 37
2.11 Documentation of Significant Changes 40
3.0 RESPONSIVENESS SUMMARY 41
Appendix CONCURRENCE OF TIIE STATE OF OREGON
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FIGURES
1 Facility Location Map, Umatilla Depot Activity 8
2 Location of Explosives Washout Lagoons' 9
3 TNT Contamination 15
4 RDX Contamination 16
TABLES
1 .: Physical and Chemical Properties of the Explosives 18
2 Health Effects Criteria for Contaminants of Concern 20
3. Summary of Carcinogenic and Noncarcinogenic Risks 22
4 Summary of Risk-based Remedial Action Criteria for Multiple
Pathway Direct Contact Exposure 25
5 Comparative Evaluation of Alternatives 32 .
6 Cost and Effectiveness of Alternatives as a Function
of Excavation Depth 33 .
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ARARs
BRAC
CERCLA
CFR .
cy
DNB
2,4-DNT
2,6-DNT
DoD
DOE
EPA
EPIC
FFA
HEAST
HI
HMX
HRS
IRIS
MAIV
N-Tetryl
NA .
NAAQS
."
ACRONYMS AND ABBREVIATIONS
Applicable or relevant and appropriate requirements
Base Realignment and Qosure
Comprehensive Environmental Response, Compensation, and
Liability Act of 1980
Code of Federal Regulations
Cubic yards
1,3-Dinitrobenzene
2,4-Dinitrotoluene
2,6-Dinitrotoluene
Department of Defense
Department of Energy
Environmental Protection Agency
Environmental Photographic Interpretation Center
Federal Facility Agreement
Health Effects Assessment Summary Tables
Hazard Index
Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (High Melting
Explosive)
Hazard Ranking System
Integrated Risk Information System
Mechanically agitated in-vessel
2,4,6- Tetianitro-N-methylaniline
Not applicable
National Ambient Air Quality Standards
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NB
Nitrobenzene
NCP
National Oil and Hazardous SubstartcesPollution Contingency Plan
NEPA
National Environmental Policy Act
NPL
National Priorities List
O&M
Operations and maintenance
OAR
Oregon Administrative Rules
ODEQ
ORNL
Oregon Department of Environmental Quality
Oak Ridge National Laboratory
ppm
Parts per million (equivalent to p.glg and mglkg)
RAC
Remedial action criteria
RCRA
Resource Conservation and Recovery Act
RDX
Hexahydro-1,3,5-trinitro-1,3,5-triazine (Royal Demolition Explosive)
RID
Reference dose
RIIFS
Remedial investigation and feasibility study
ROD
Record of Decision
SARA
Superfund Amendments and Reauthorization Act of 1986
TBC
To be considered
TCLP
Toxicity characteristic leaching procedure
TNB
1,3,5- Trinitrobenzene
TNT
2,4,6- Trinitrotoluene
TRC
Technical Review Committee
UMDA
u.S. Army Depot Activity at Umatilla
USATHAMA U.S. Army Toxic and Hazardous Materials Agency
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SECTION 1
DECLARATION OF THE RECORD OF DECISION
SITE NAME AND LOCATION
u.s. Army Depot Activity, Umatilla
Explosives Washout Lagoons, Soils Operable Unit
Hermiston, Oregon 97838-9544
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected remedial action for the Explosives Wash-
out Lagoons Soils Operable Unit at the U.S. Army Depot Activity, Umatilla (UMDA),
in Hermiston, Oregon, which was chosen in accordance with the Comprehensive
Environmental Response, Compensation, and Liability Act of 1980 (CERClA), as
amended by the Superfund Amendments and Reauthorization Act of 1986 (SARA),
and, to the extent practicable, the National Oil and Hazardous Substances Pollution
Contingency Plan (NCP). The decision is based on the administrative record for this
site. Documents contained in the record are identified in Section 2.2. .
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 this site, if not addressed
by implementing the response action selected in this Record of Decision (ROD), may
present an imminent and substantial endangerment to public health, welfare, or the
environment.
DESCRIPTION OF THE SELECfED REMEDY
This operable unit is the first of two that are planned for the Explosives Washout
Lagoons. It addresses contaminated soils at the lagoons and is the final remedial
action planned for those soils. The purpose of the soils operable unit is to reduce the
risks associated with exposure to lagoon soils and thus address one of the principal
threats at the site. The second operable unit will involve continued study and possible
remediation of contaminated groundwater beneath the ~agoons; this operable unit is
being integrated with facility-wide groundwater issues.
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The major components of the selected remedy include the following:
.
Excavation of lagoon soils having 2,4,6-trinitrotoluene (TNT) or
hexahydro-l,3,5-trinitro-l,3,5-triazine (commonly referred to as Royal
Demolition Explosive or RDX) concentrations greater than 30 parts per
million (ppm) each (initially estimated to be 6,800 tons of soil);
.
Onsite biological treatment of excavated soils, via composting" to TNT
and RDX concentrations of 30 ppm or less; and
.
Replacement of composted soils in the excavation, covering the area with
two feet of clean soil, and revegetating.
_0 '
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 practica~le, and satisfies
the statutory preference for remedies that employ treatment that reduces toxicity,
mobility, or volume as a principal element.
, .
;..,
This remedy is intended to provide sufficient remediation for the probable scenario of
future industrial use. Because the remedy might not allow for unrestricted future use
of the site, the five-year review Will apply to this action. That review will' include
consideration of the following elements: .
-..
.
Explosives concentrations meas~red following soil treatment, since actual
concentrations might be sufficiently low to allow for unrestricted use
, ..
.
The hazard index (HI) of 1,3,5-trinitrobenzene, as recalculated following
chemical-specific toxicity studies recently initiated by the U.S. Army
.'
Continued integrity of the clean soil cover
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LEAD AND SUPPORT AGENCY ACCEPTANCE
OF THE RECORD OF DECISION,
U.S. ARMY DEPOT ACTIVllY t::\1ATILIA,
EXPLOSIVES WASHOUT lAGOONS, SOILS OPERABLE UNIT
Signature sheet for the foregoing Record of Decision for the Explosives Washout
Lagoons Soils Operable Unit final action at the U.S. Arniy 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. .
0.(~.~
~. Walker
Deputy Assistant Secretary of the Army
(Environment, S.afety, and Occupational Health)
7'/3 U/7 Z--
Date
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LEAD AND SUPPORT AGENCY ACCEPTANCE
. OF THE RECORD OF DECISION,
U.S. ARMY DEPOT ACTIVITY UMATILLA,
EXPLOSIVES WASHOUT LAGOONS, SOILS OPERABLE UNIT (CO NT.)
Signature sheet for the foregoing Record of Decision for the Explosives Washout
Lagoons Soils 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.
~ ~L-. ~
Lieutenant Colonel William D. McCune
Commander, U.S. Army Depot Activity, Umatilla
-<~&r ~
Date
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LEAD AND SUPPORT AGENCY ACCEPTANCE
OF THE RECORD OF DECISION,
U.S. ARMY DEPOT ACTIVI1Y UMATILLA,
EXPLOSIVES WASHOUT LAGOONS, SOILS OPERABLE UNIT (CO NT.)
Signature sheet for the foregoing Record of Decision for the Explosives Washout
Lagoons Soils 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.
ana A Rasmussen
Regional Administrator, Region 10
U.S. Environmental Protection Ag~ncy
1- L S--Jf "2.-
Date
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LEAD AND SUPPORT AGENCY ACCEPTANCE
OF THE RECORD OF DECISION,
U.S. ARMY DEPOT ACTIVITY UMATILLA,
EXPLOSIVES WASHOUT LAGOONS, SOILS OPERABLE UNIT (CONT.)
Signature sheet for the foregoing Record of Decision. for the Explosives Washout
Lagoons Soils 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.
~~~~
Frederic J. Hansen
Oregon Department of Environmental Quality
._~ 130/q~
Date
Note: The State of Oregon's Letter of Concurrence is appended to this Record of
Decision.
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SECTION 2
DECISION SUMMARY
This Decision Summary provides an overview of the problems posed by the conditions
at the UMDA Explosiv.es Washout Lagoons, 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 is 'located in northeastern Oregon in
Morrow and Umatilla Counties, approximately 5 miles west of Hermiston, Oregon, as
shown in Figure 1. The installation covers about 19,700 acres of land. The UMDA
Explosives Washout Lagoons (Site 4) are located in Coyote Coulee, a linear depression
in. the center of the UMDA installation, as shown in Figure 2.
The Explosives Washout Lagoons are two adjacent, unlined, rectangular lagoons con-
structed in the native sandy-gravelly soil. The north and south lagoons measure 80 feet
by 39 feet and 80 feet by 27 feet, respectively, and both are 6 feet deep. A 15-foot-
wide gravel berm separates the lagoons, and gravel berms encircle both. The depth
from the bottom of the lagoons to groundwater generally varies from 45 to 50 feet.
The lagoons are typically dry; any collected precipitation tends to infiltrate rapidly.
There is virtually no vegetation in the lagoons or along the berms.
UMDA was established as an Army ordnance depot in 1941 for the purpose of storing
and handling munitions. Access is currently restricted to military personnel and autho-
rized contractors. However, the ordnance storage mission at UMDA has been trans-
ferred to another installation, and UMDA is scheduled for future realignment under
the Department of Defense (DoD) Base Realignment and Qosure (BRAC) program.
Under this program, it is probable that the Army will eventually vacate the site; owner-
ship could then be relinquished to another governmental agency or private interests.
Light industry is considered to be the most likely future land use scenario; future resi-
dential use is also a possibility.
Northeastern Oregon, the setting for UMDA, is characterized by a semi-arid, cold
desert climate, an average annual precipitation of 8 to 9 inches, and a potential evapo-
-transpiration 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.
Groundwater occurs primarily in two settings: in an unconfined aquifer within the over-
lying deposits and weathered basalts, and in a vertical sequence of semi-confined, and
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", 1
"\ ,i m p
,-' ;. -1 I
","" . SUnnYSid..&'f~ ~ ,
.~ " :
i '.~ '..", " \"
\~"::....... .. '> i)
\ .
"
00
Gilliam County
...
N
0 10
20
Scale in Miles
Figure 1
Facility location M
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\0
818 "-----'--------------1
itl,:g, .
gl'lij , "
. ~15 ' ,
;-----------------------------------r-------J -~
1 ....., ./ /. !
" ............ ;//.. l . I I
. . '.' ," .
, Explosives .... ","':".. ,
1 washoul I I .. .
lagoons \...... / .... . , Igloo Block K Igloo Block E i
I ~.)('~I 't\.... i .
i . 550 .."....."" If J ... ,
'I .../........ /... / .. Igloo Block D i
..! I ,
, ... I I 1
! i~' i
I' ."" 'J'I.'J ..........'\ \ \ 1\ i 1 i
..... \ \ \ I ~ 0 200 400 "
" \, J \ I \ a,....- I Igloo Block C
, \ ...../ // J I Approximate Seale In Feet .. i
, \, ......., ...;." i '/8 "''t..Q - _.:, ,
, '..." Co ole Road...;-' .... ::Ii : ~ I ,
I If i . -0 G> i
i Igloo Block B !
'I ,
Igloo Block F ,
L,' "
"'" .
""'-~ ,
------ Igloo Block A ,
-------~--- i
..................--- .
--'- I ,
............. .........
, "'---- . "
.----.........
-............................ .
UM '---. I
DABounda ----- I
. ry ---_...J
~
NORTH
,0
I
Approximate Seale in Feet
2000
4000
I
LEGEND
Figure 2
Location 01 Explosives
Washout Lagoo
,...... 525 .......
Surface elevations
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confined aquifers within the basalt. Groundwater flows trend to the north and north-
west. However, regional flow gradients in the uppermost aquifer are influenced by
irrigation, pumping, and leakage from irrigation canals. The Columbia River flows
from east to west approximately 3- miles to the north of the UMDA boundary, and the
Umatilla River flows from south to north approximately 1 to 2 miles to the east. No
natural streams occur within UMDA; the facility is characterized by areas of closed
drainage.
The region surrounding UMDA is primarily used for irrigated agriculture. The popula-
tion centers closest to UMDA are Hermiston (population 10,075), approximately
5 miles east; Umatilla (population 3,032), approximately 3 miles northeast; 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 Irrigon) draw from groundwater within a 4-mile
radius of UMDA The Columbia River is a major source of potable and irrigation
water, and is also used for recreation, fishing, and the generation of hydroelectric
power. The principal use of the Umatilla River is irrigation.
2.2
SITE HISTORY AND ENFORCEMENT ACl'lVlTIES
From the 19505 until 1965, UMDA operated an onsite 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 con-
sisted of the following:
.
2,4,6- Trinitrotoluene (TNT)
.
Hexahydro-l,3,5-trinitro-l;3,5-triazine (commonly referred to as Royal
. Demolition Explosive or RDX)
.
Octahydro-l,3,5, 7-tetranitro-l,3,5, 7-tetrazocine (commonly referred to as
High Melting Explosive or HMX)
.
2,4,6- Tetranitro-N-methylaniline (N- Tetryl)
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), occurring 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 con-
structed in the 195()s and used until 1965, when plant operations and all discharges to
. the lagoons ended. A total of 85,000,000 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 environ-
mental quality at UMDA with regard to the past use, storage, treatment, and disposal
of toxic and hazardous materials. Based on imagery analysis provided by EP A'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 Cohtamination'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 the alluvial aquifer.
Subsequent investigations confirmed the presence of explosives in the soil and
groundwater.
In 1984, the Explosives Washout Lagoons were evaluated using EPA's Hazard Ranking
System and received a score in excess of 28.5. As a result, the lagoons were proposed
for" inclusion on the National Priorities List (NPL) in 49 Fed. Reg. 40320 (Octo-
ber 15, 1984). They were formally listed on the NPL in 49 Fed. Reg. 27620 (July
22, 1987) based on the Hazard Ranking System (HRS) score and the results of the
installation Resource Conservation and Recovery Act (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 lead agency for initiating response
actions at UMDA. One of the purposes of the FFA was to establish a framework for
developing and implementing appropriate res,ponse actions at UMDA in accordance
"with CERCLA, the NCP,and Superfund guidance and policy. Remediation of contam-
inated soil and groundwater 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 determine the nature and extent of con-
tamination and to identify alternatives available to clean up the facility.
The following documents outline the results of the site investigations and assessments
of cleanup actions for the Explosives Washout Lagoons:
1.
Risk Assessment for the Explosives Washout Lagoons (Site 4), Umatilla'Depot
Activity, Hermiston, Oregon. Prepared by Dames & Moore for the U.S. Army
Toxic and Hazardous Materials Agency. 1992. "
-------
2.
Explosives Washout Lagoons Soils Operable Unit Supplemental Investigation,
. Technical and Environmental Management Suppon of Installation Restoration
Technology Development Program, Umatilla Depot Activity, Hermiston, Oregon.
Prepared by Morrison Knudsen Environmental Services/CH2M HILL for the
U.S. Army Toxic and Hazardous Materials Agency. 1992.
Feasibility Study for the Explosives Washout Lagoons (Site 4;' Soils Operable Unit,
Umatilla Depot Activity, Hermiston, Oregon. Prepared by CH2M HILL/Morrison
Knudsen Environmental Services for the U.S. Army Toxic and Hazardous
Materials Agency. 1992.
3.
4.
Optimization of Composting for Explosives Contaminated Soil. Prepared by Roy
F. Weston for the U.S. Army Toxic and Hazardous Materials Agency. 1991.
5.
Arthur D. Little, Inc. Testing to Determine Relationship Between Explosive
Contaminated Sludge Components and Reactivity. Prepared for the U.S. Army
Toxic and Hazardous Materials Agency. Report No. AMXTH-TE-CR-86096.
January 1987.
6.
Oak Ridge National Laboratory (ORNL). Characterization of Explosives
Processing Decomposition Due to Composting. . Phase II Final Report.
ORNLfTM-12029. Prepared under DOE Interagency Agreement
No. 1016-B123-A1. November 1991.
2.3
HIGHLIGHTS OF COMMUNITY PARTICIPATION
In 1988, the UMDA command assembled a Technical Review Committee (TRC) com-
posed of elected and appointed officials and .other interested citizens from the sur-
rounding communities. Quarterly meetings provide an opportunity 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 supplemental investiga-
tion and feasibility study for the Explosives Washout Lagoons Soils Operable Unit. In
those meetings, the TRC was informed as to the scope and methodology of the lagoon
soils investigation and remediation.
The Feasibility Study and Proposed Plan for the Explosives Washout Lagoons Soils
Operable Unit were released to the public on April 27, 1992. The public comment
period started on that date and ended on May 27, 1992. The documents constituting
the administrative record were made available to the public at the following locations:
UMDA Building 1, Hermiston, Oregon; the Hermiston Public Library, Herrniston,
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-City Herald, and the East
Oregonian in April 1992. .
-------
A public meeting was held at Armand Larive Junior High School, Hermiston, Oregon,
on May 5, 1992, to. inform the public of the preferred alternative arid to seek public
comments. At this meeting, representatives from UMDA, the U.S. Army Toxic and
Hazardous Materials Agency (USATHAMA), EPA, ODEQ, and CH2M HILL (an
environmental consultant) answered questions about the site and remedial alternatives
under consideration. A response to comments received during this period is included
in the Responsiveness Summary appended to this ROD. .
2.4
SCOPE AND ROLE OF OPERABLE UNIT
Operable units are discrete actions that constitute incremental steps toward the final
overall remedy. Operable units can be actions that completely address a geographic
portioi1 of a site or a specific, problem, or can be one of many actions that will be
taken at the site. .
The Explosives Washout Lagoons site was divided into two operable units, soils and
groundwater, to facilitate early remediation of the soil. The threats described in this
ROD are those associated with the contaminated soil present at the lagoons. The Soils
Operable Unit cleanup strategy presented here is considered a final action only for
that soil.
Future groundwater usage is not assumed or addressed in this ROD, since this remedy
is intended to address exposure to soil. UMDA groundwater, including groundwater
associated with the Explosives Washout Lagoons, is being investigated on an
installation-wide basis. The final remedial actions for the groundwater and for
remaining portions of the UMDA installation will be proposed following completion of
ongoing investigations.
2.5
SITE CHARACfERISTICS
The original source of contamination at the UMDA Explosives Washout Lagoons was
the washwater discharge from washout plant operations. No other contamination
sources are suspected. The type of contamination is explosive compounds, primarily
TNT and RDX.
Several soil and groundwater investigations have been conducted at the Explosives
Washout Lagoons from 1981 to the present. Samples collected from soil borings
drilled beneath and surrounding the lagoons have been used to' determine the vertical.
. and horizontal extent of soil contamination. A network of 34 groundwater monitoring
wells has been used to identify and map groundwater contamination. The investigation
results are summarized as follows:
-------
- .
.
The contaminants most frequently detected in the soil are TNT, RDX,
HMX, TNB, and 2,4-DNT. Tetryl, 2,6-DNT, DNB, and NB are rarely if
ever detected, and then only at low (less than 5 ppm) concentrations.
No additional organic compounds were detected, and inorganic
compound concentrations were comparable to regional background
concentrations. .
.
Total explosives concentrations are well below the 12 percent minimum
required for explosive reactivity. Therefore, "the soil is neither a RCRA
characteristic waste for reactivity, nor is it sufficiently similar to RCRA
explosives-derived listed wastes, which are listed solely for. the.
characteristic of explosive reactivity.
Soil concentrations of NB and 2,4-DNT (when detected at all) are suffi-
ciently low that leachate concentrations would not be expected to exceed
Toxicity Characteristic Leaching Procedure (TCLP) levels. NB and 2,4-
DNT are the only explosives contaminants on the TCLP list. Therefore,
th~ soil is not a RCRA characteristic waste for toxicity.
..
Contamination extends vertically from the soil surface to the water table
(45 to 50 feet below the lagoons). TNT and RDX concentrations typic-
ally range from 100 ppm to 2,000 ppm from the surface to a depth of
3.5 feet; they are generally less than 30 ppm below that. TNT
concentrations exceeding 2,000 ppm have been observed in the top inch
of soil, with a m~mum of 88,000 ppm detected. HMX concentrations
generally range from below detection «1 ppm) to 100 ppm throughout
the soil column. TNB concentrations generally vary from 2 ppm to
47 ppm throughout the soil column. 2,4-DNT is typically not detected in
the upper 6 feet of soil; concentrations .are relatively low throughout the
remainder of the soil column "(below detection [< 1 ppm] to 5 ppm).
.
Contamination does not extend laterally beyond the berms surrounding
the lagoons, except at the interface between the unsaturated soil and the
groundwater.
.
TNT and RDX concentrations up to 5,500 ppm are observed in the cen-
tral berm dividing the two lagoons. Explosives concentrations measured
in the perimeter berms are less than 20 ppm.
Vertical concentration profiles for TNT and RDX are shown in Figures 3 and 4.
These profiles are based on four sampling boreholes .installed in 1991. The total
volume of soil contaminated with detectable levels of one or more explosives is approx-
imately 30,000 cubic yards (cy).
-------
~
VI
FIGURE 3
TNT CONTAMINATION I.
39'
15'
51'
... ..
.
.
.
.
.
,
.
.
,
,
,
,
,
,
.
,
.
.
I-----------------------------------II----------~I------------------------------------------.
I - II .1 I
: :: CENTER:: :
I " BERM .1 .
. . :- :- . SOUTH LAGOON NORTH LAGOON . -: -: . :- :- .
. . . . . . .
. . . . . .
. . . . .
. . . . .
',0, 0,','
. . . . .
. . . .
. . . .
. . . .
. . . . . .
. . . . . . . . . . . . . .
. . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . .
':.:.: ":':':': -:.:::::::....::::::::::::::::::::::::::-..:.:::::::::::::::::::::::::::::::'
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . I . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
""""""0""".""""""""""""""""""I"""""""".................
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
: . : . : . : -: . :- : . : . : . : . : . : . : . : . : -: . : . : . : . : . : . : . : . : . : . : . : . : . : . : . : . : . : . : . : . : . : . : . : . : . : . : . : -: .
. . . . . . . . . . . . ... . . . . . . . . . . . . ... . . . . . . . . . . . . . . ...
. . . . ..... . . . . . ...... . . . . . . . . . . . ...... . . . . . . . . . . . . . ."..
. . .......,. . ........... . . . . . . , . . . . ........... . . . .,.................
.'. '.............-.............' . . . . . . . . . . . ....................................
.............................. . . . . . . . . . . .....................................
..................'.......'...'.'.'.'.......'..................'.....'.........................'...............................................'...'.'...
............................. . . . . . . . . . . . ....................................
............................ . . . . . . . . . . . ...................................
"'.."."'.""'.."""". . . . . . . . . . . . . "'..'.'..'..."..............'. . .
. ",....,.,.,.,.",."...... . . . . . . . . . . . . ......... . . . . ......... . . .
. . . . . . . . . . . . . . . . . . . . . . . . 0 . . . '".,". . . . . . . . . 0 . . . . 0
,'......."..............,..'...0.........'.'.'................0".............0.........,...,
. . . . . . . . . . . . . . . 0 . . . . . . . , . . . . . . . . " , , . . . . . . . . . . . .
, . . . . . . . . . . . . . . . . . . , . . . . . . . 0 . . . 0 . . . 0 . . . . . . , . . . . .
. . . . . . . 0 0 . . . . . 0 0 . . . . . . . . . , . . . . . . . . . 0 . . 0 . . . . . 0 . . . ,
. . . " . . . . " . . " . . . , . . . . . . . . . . . . 0 . . . . . . . . . . . . . . . 0 0 . . .
. . . . . . . . . 0 . . .,....... . . . . . . . . . . , . . 0 . . . . . . . . . 0 . . 0 . . . . . . "
53'
.
,
,
.
.
.
,
,
.
.
.
.
.
.
.
.
.
,
.
.
,
.
... .
, . , .
vvvvvvvvvvvvvvvvvvvvvvvvv'~vvvvv
"V'V"V'V"
~==./'_~""''''/\.:
.. '. . . . .
v v v v v v 'V' v v v v v 'v' v v v'V' v v v v v V'........:.v......v......v...,:..........v......v....:.,,;....v.....v;
~~
:~~~
v"\:.."".""-".."\,/""(.A..... ,.~,~"""."""."'--., ,,""".- '0' '.' '.' """""'.'''''.''''''''''''''''.' '0' ..... '." -.'''''('''' '.' .....~ ,.....
GROUNDWATER
LEGEND
> 1000 ppm
100 ppm to 1000 ppm
30 ppm to 100 ppm
10 ppm to 30 ppm
t::::::::::::::::::::1
E : ::: : : : :::1
Below Detection Limit (1 ppm) to 10 ppm
-------
~
0\
FIGURE 4
RDX CONTAMINATION:
39'
15'
51'
I" -.............. ...... ............ ........!"'.. ............ ...... .. -II .. .......... ........ -,'"'''' ............ .................. ............ .. _........ ......................-.
I II ,I I
: :: CENTER:: :
1 " BERM ,I
... ..
,
.
,
,
,
,
,
.
,
.
,
,
,
,
,
.
.
.
53'
SOUTH LAGOON
NORTH LAGOON
. . . . . .
. . . . . I
. . . . . .
. . . . . . .
. . . . . . . .
. . . . . . . .
. . . . . . . . ... .. . .
. . . . . . . . . . . . . . . . . . . . .
.",',0.'.',',',',',',',',',",',',',',',',',:',.....,','. ""'0""""
. . . . . . . . . . . .'....'... . . . . . . ..,.......................
. . . . . . . . . """""""'" . . "","""""""""'"
',','.',',',',',:',',',",",",',',',',',",',',',',",',',',',',",",',',',',',",',',',",',',",",",',",',.
. . . . . . . . """"""""""""""" . . . . . . . . . . .to. ..
o . . . . . . """"""""""""'.... . . . . . . . . . . ".."""""" .............. ..
. . . . . . . . ............................ . . . . . . . . . . . . """""""'..".""""""'"
. . . . . . . . ........................... . . . . . . . . . . . "..."""."'."'.'."""""'"
. . . . . . . . . .......................... . . . . . . . . . . . . """""""""'.".""""""
. . . . . . . . . . . . . . . ........... . . . . . . . . . . . . .......t...........................
, . .... ."" "., . ... ,. .'.'-'
...'- .-... ....."...... .........'C.'"
,;?,....,...;.....~;.....;..............,....,....,;,?,i,I~>t~, ',;,',
,
.
.
,
,
,
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,
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,
,
,
.
.
,
,
,
,
,
,
... .
.. . . .......... . . .
.. . ........... . .
. . . .......... . . .
. . . . ....... . . .
.. ....... ........ . . .
........ . . . .....,. . . .
........ . . . . . . . . . . .
......,.. . . . . . . . . . .
....."", . . . . . . . . . . .
.... . . . . . . . . . . . . .
..,. . . . . . . . . . . . . .
.. . . . . . . . . . . . . .
. . . . . . . . . . .
. . . . . . . . .
. . . . . . .
. . . . . .
tt(+')'\'/';~:;'r': ~;(f:V'~- ',>'. '.,','.,~'>':< ',: ~'--:'/':::'::::i:::::::;::::@~f:::
. . . .. . ,
,." v.v~.' ......, .v." ''''''''-''''.~''''''''v~''v'''.''''~'v'"./""'''~.v'""",,,'''...................,
~~'-,
~
~ "~~~v::~-
GROUNDWATER
~."."-".:;"~.""""""'''''.'''''~~~.'''''0.~'V'''~.''''''"""""""""""""""~"""''''''.'''''''''''.''.'''''':;'':::::
~~v~-~v
/'>.~~~~:
... ,'. ~~~~-::~..-:~:~0.-:..~-'::-"~"":::-:-:::~,-:-,~;",~~'
LEGEND
1&
.
1:::::::::::::::::::::1
1::::::::::1
1 00 ppm to 1000 ppm
30 ppm to 100 ppm
10 ppm to 30 ppm
Below Detection Limit (1 ppm) to 10 ppm
-------
Physical and chemical properties of the explosives are .provided in Table 1. 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.
Potential routes for migration of th~ explosives include the following:
.
Air: Airborne transport of soil contaminants might occur via the disper-
sion of soil particles, particularly if soil-disturbing activities are performed
at the lagoons. Passive transport of soil contaminants is unlikely given
the low volatility of the explosives.
.
Surface water: There is little potential for surface water transport of the
explosives. The lagoons are not located within a floodplain, there is
virtually no run-on to or run-off from the lagoons due to the raised
berms, and there are no natural or man-made drainage systems in the
area of the lagoons. The low precipitation rate and high soil perme-
ability allow for ready percolation of any rain falling directly onto the
lagoons.
.
Subsurface: Infiltration of precipitation provides a potential subsurface
pathway for migration. However, the rate of transport ~s expected to be
low due to the low precipitation and high evaporation rates in the region.
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 baseline risk assessment was conducted by the Army to estimate the risk posed to
human health by the Explosives Washout Lagoons should they remain in their current
state with no remediation. The risk assessment consisted of an exposure assessment,
toxicity assessment, and human health risk characterization. The exposure assessment
detailed the exposure pathways (such as dust inhalation) that exist at the site for
various receptors. The toxicity assessment documented the adverse effects that can be
. caused in a receptor as a result of exposure to a site contaminant. .
The health risk evaluation used both the exposure concentrations and the toxicity data
to determine an HI for potential noncarcinogenic effects and a cancer risk level for
potential carcinogenic contaminants. In general, an HI of less than or equal to
1 indicates that even the most sensitive population is not likely to experience adverse
-------
Table 1
Physical and Chemical Properties of the Explosives
TNT 2,4.DNT 2,6.DNT TND DNB RI>X 11M X Ttlryl
CAS Registry No. 118.96.7 121.14.2 606.20.2 99.35.4 99.65.0 121.82.4 2691.41.0 479.45.8
Empirical Fonnula ~H~N106 ~H6N204 ~H6N204 C6H3N306 C6H4N204 ~H6N606 C4H8N808 ~H'iN'i08
Molecular Weight 227.15 182.15 182.15 213.12 168.12 222.15 296.20 287.17
Density (g/cm3) 1.65 1.521 1.538 1.63 1.575 1.83 1.90(~ ronn) 1.73
Melting Point ("C) 80.75 72 66 122 90 205 286 129.5
Vapor Pressure (mm Hg, 25°C) S.51xl0.6 2.17xl0.4 5.67x10.4 3.03xl0.6 1.31xl0.4 4.03xl0.9 3.33xl0.14 5.69xl0.9
Aqueous Solubility (mg/L, 25°C) 150 280 206 385 533 60 5 80
Henry's Conslant (alm.m3/mole, 25°C) l.IOxl0.8 1.86xl0.7 4.86x10.7 2.21xl0.9 5.44x 10,8 1.96x 10' 11 2.6Oxl0.15 2.69x10.11
Log Ko\V 2.00 1.98 1.89 1.18 1.49 0.87 0.26 1.65
K (ml/g) LOO 0.68 0.21 2.23 0.45 0.21 0.44 0.71
R 4.46 3.34 1.72 8.72 2.55 1.73 2.51 3.46
Bio-concentration raclor (BCF) (rish) 8.95 10.6 9.82 2.65 4.70 1.50 0.49 6.31
......
00
-------
health effects. H it is above 1, there might be a concern for adverse health effects.
The degree of concern typically correlates with the magnitude of the index if it is
above 1. The cancer risk level is the additional chance that an exposed individual will
develop cancer over the course of a lifetime. It is expressed as a probability such as
1 x 10.0 (one in one million).
Risk assessments involve calculations based on a number of factors, some of which are
uncertain. First, the health effects criteria. of specific chemicals are often based on
limited laboratory studies .on animal species which are then extrapolated to humans.
Further, the exposure scenario requires estimation of the duration and frequency of
exposure, the identity of the exposed individual, and the contaminant concentration at
the point of exposure. H the value of a factor required for the risk assessment is un-
certain, . a conservative estimate is used so that a health-based exposure level or con-
centration can be calculated. For example, in order to calculate a reference dose for
humans, toxicity assessments divide doses observed to cause health effects in animals
by an uncertainty factor to account for species differences and human population vari-
ability. The uncertainty factors for the explosives of concern are given in Table 2. In'
the case of uncertainties associated with exposure scenarios, the most conservative
plausible scenario is selected. For ex~mple, in the Explosives Washout Lagoons risk
assessment, since it is possible that the site might be used for residential purposes, risk
values were calculated for a residential-use scenario.
Contaminants of concern in the UMDA Explosives Washout Lagoons Soil Operable
Unit were identified as those explosives detected in soil samples collected during the
lagoon investigations. They were: ..
. TNB
. DNB
. TNT
. 2,4-DNT
. HMX
. NB
. RDX
The populations at risk of exposure to these explosives were identified by considering
both current and future use scenarios. Currently, public access to the UMDA facility
is restricted, and there is little incentive or opportunity for trespassers to approach the
lagoon area, so public exposure is unlikely. There are no operations being conducted
in the lagoon area other than remediation, so unplanned exposure of military person-
nel is also .unlikely. Therefore, the potential for current exposure was judged to be low
and risks associated with current exposure scenarios were not evaluated.
The probability of future exposure to human receptors was considered high, since it is
likely that DoD will eventually vacate UMDA. A light industrial land use scenario is -
-------
N
o
Table 2
Health Effects Criteria for Contaminants of Concern
Explosives Washout Lagoons (Site 4), UMDA
Slope Factor Weight or Reference
Contaminant or (m&fk&. Evidence Dose Uncertainty Confidence
Concern day).! Source Classlncatlon Cancer Type (mglkg.day) Source Critical Effect Factor Level
1,3,5- 5.00E-05 IRIS Increased splenic 10,000 low
Trinitrobenzene weight
1,3- l.ooE-04 IRIS Increased splenic 3,000 low
Dinitrobenzene weight
2,4,6- 0.030 IRIS C urinary bladder 5.ooE.o4 IRIS Liver ereects 1,000 medium
Trinitrotoluene papillomas
2,4- 0.680 HEAST 82 liver, mammary 6.00E-04 USEPA. Hepatic alterations 1,000 low
Dinilrololuene gland 1991c
2,6- 0.680 HEAST B2 (a) 1.00E-03 USEP A. Liver, kidney, 3,000 low
Dinitrololuene 1991c neurological,
reproductive and
hematological
errects
HMX 5.ooE-02 IRIS Hepatic lesions 1,000 low
Nitrobenzene 5.00E-04 IRIS Hematologic, 10,000 low
adrenal, renal, and
hepatic lesions
RDX 0.110 HEAST C hepatocellular 3.00E-03 IRIS Inflammation of 100 high
carcinomas and prostate
adenomas .
, Tetryl 1.50E-03 Small, Skin sensitization 100 low
1988
Sources: IRIS: Integrated Risk Information System. Januaiy 1991.
HEAST: Health Effects Assessment, Summary Tables, 4th Quarter. September 1990.
EPA. 1991c: Risk Assessment Guidance for Superfund, Volume 1: Human Health Evaluation Manual, Supplemental Guidance, Standard Default Exposure Factors
Small, 1988: Residual Explosives Criteria for Treatment of Area P Soil, louisiana Army Ammunition Plant
(a) Based on potential carcinogenicity of 2,4-DNT.
\ I
1
-------
considered the most probable scenario for future use of UMDA based on site topo- .
graphy and the availability of utilities and resources. The exposed population would
consist of adult occupational workers. Future residential use is also possible, although
jt is not probable; because it is more conservative, it was also evaluated in the risk
assessment.
The exposure pathways that were identified for each of these future use scenarios
consist of the following:
.
Incidental ingestion of soil
Dust inhalation
Dermal absorption of chemicals in soil
Groundwater ingestion
.
.
.
The probability of significant exposures by other pathways was considered low. Only
the first three pathways are applicable when evaluating risks associated with direct
contact with contaminated soil. Risks associated with the ingestion of contaminated
groundwater will be assessed in great detail during the study of the groundwater opera-
ble unit.
For purposes of calculating exposure, TNT, RDX, HMX, 1,3,5-TNB, and 2,4-DNT soil
concentrations were conservatively assumed to be the maximum concentrations ob-
served during the remedial investigation. Soil 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 obtained
from EP A'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.
The basic toxicity information and health effects criteria for the explosives, including
carcinogenic data from EP A databases and the models from which the risk values were
derived, are presented in Table 2. All of the explosives are potentially toxic. In addi-
tion, both TNT and RDX are classified as potential human carcinogens (Group C),
and 2,4-DNT is classified as a probable human carcinogen (Group B).
Because of the paucity of toxicity data for TNB, EPA derived a reference dose (RID)
by analogy to DNB. This analogy is considered appropriate and acceptable because of
their structural 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.
Using the Table 2 data and the calculated chronic daily intake factors, excess cancer
risks and noncancer His were calculated for each of the three direct soil contact
-------
pathways and two exposure scenarios, with the assumption that no remediation of soils
takes. place. The results are summarized in Table 3. Excess cancer risks are based on
TNT, RDX, and 2,4-DNT. All chemicals of concern were evaluated for contribution to
noncancer risk.
Table 3
Summary of Carcinogenic and Noncarcinogenic Risks
(Assuming No Remediation Occurs)-
Residential Use Light Industrial Use
Cancer Noncancer . Cancer Noncancer
Pathway Risksb Risksc Risksb RisksC
Ingestion 1.77E-03 1120 . 3.33E-04 40.5
Inhalation 1.20E-05 0.66 4.9E-06 0.60
Dermal Contact 8.23E-03 3067 4.36E-03 546
Combined Pathways, Direct 1.00E-02 4188 4.7E-03 587
Contact with Soil Only
aConcentrations used to calculate risks were derived from surface samples collected
in the lagoons.
bEJecess lifetime cancer risk to an individual. -
CfII (an HI of 1.0 or lower generally indicates that no adverse effects would be
expected).
If no soil remediation occurs, the excess cancer risks associated with direct soil contact
assuming a reasonable maximum exposure scenario would be as follows:
.
Residential, 1.00 x 10-2
Light Industrial, 4.70 x 10-3
.
The non~ncer HIs associated with direct soil contact assuming a reasonable maximum
exposure scenario are as follows: .
.
Residential, 4188
Light Industrial, 587
.
The NCP states that the acceptable risk range for carcinogens is 1 x 10-4 to 1 X 10-6
[40 CFR 3oo.430(e)(2)(i)(A)(2)]. For systemic toxicants (i.e., constituents having a
. noncancer health effect), the NCP states the following:
-------
"For systemic toXicants, acceptable exposure levels shall represent concentration
levels to which human populations, including sensitive subgroups, may be ex-
posed without adverse effect during a lifetime or part of a lifetime, incorporat-
ing an adequate margin of safety" [40 CFR 300.430(e)(2)(i)(A)(1)].
As discussed earlier, acceptable exposure levels are usually evaluated in terms of the
HI; an HI of less than or equal to 1 generally represents an acceptable exposure. .
However, the NCP further states that remedial action objectives must consider
"(f)actors related to uncertainty" [40 CFR 300.430(e)(2)(i)(A)(4)]. Therefore, the
calculated HIs must be considered within the context of the uncertainty factor, a
conservatism that is built into the EP A-derived RID. For example, if the uncertainty
factor is several orders of magnitude greater than the calculated HI, an HI somewhat
greater than one may be. acceptable. . -- .
The potential risks associated with current soil contamination at the lagoons clearly
exceed the acceptable carcinogenic risk range. In addition, the calculated HI exceeds
1 by two to three orders of magnitude, a level that is comparable to the uncertainty
and therefore unacceptable. Therefore, in the event of likely future land use changes
brought about by UMDA's inclusion in the BRAC program, 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 health, welfare, or the environment.
2.6.2 Environmental Evaluation
An ecological assessment that includes the Explosives Washout Lagoons is underway as
part of the installation-wide RIIFS. Results were not yet available, so qualitative obser-
vatiQns and literature information were included in the feasibility study for the Explo-
sives Washout Lagoons Soils Operable Unit.. The lagoons and surrounding berms are
devoid of vegetation, despite the fact that plant growth typical of the high desert cli-
mate is well-established in the area around the lagoons. In addition, explosives concen-
trations in surface soils at the lagoons exceed those levels determined in laboratory
studies to cause marked stress to vegetation.
Although theUMDA installation is part of the critical winter range and habitat for
several threatened and endangered avian species, none of these are directly affected by
the Explosives Washout Lagoons, nor are they likely to be in the future.
2.6.3 Remedial Action Criteria
Neither state nor federal regulations contain chemical-specific soil cleanup standards
for the contaminants of concern. However, both authorities provide a framework for
. developing risk-based remedial action criteria. The State of Oregon requires cleanup
-------
to background or, if that is not feasible, the lowest levels that are protective of human
health and the environment and feasible. The NCP provides guidelines in terms of
acceptable carcinogenic and non-carcinogenic risk. Therefore, the health criteria cited
in Table 2, such as slope factors and reference doses, become "ta-be-considered"
(TBC) criteria for protectiveness and in evaluating compliance with applicable or
relevant and appropriate requirements (MARs).
Potential risk-based remedial action criteria (RAC) were calculated based on direct
contact with lagoon soils. RAC for the contaminants of concern were developed to
identify the soil concentrations equivalent to excess cancer risks of 1 x 10-0, 1 x 10-5,
and 1 x 10-4, and noncancer risks with HIs of 0.1, 1, and 10. The results are provided.
in Table 4. . ..
2.7
DESCRIPTION OF ALTERNATIVES
A range of general response actions was considered for remediating the UMDA Explo-
sives Washout ~goons soil. The actions were first screened for general applicability,
then several that appeared to be appropriate for the site were evaluated. for effective-
ness, implementability, and, to a lesser extent, cost. The actions evaluated included:
.
No Action
Institutional controls (monitoring)
Containment (engineered cap, soil cover, vegetative cover, surface
controls)
Removal
Immobilization (physical/chemical solidification and stabilization)
Thermal treatment (via incineration) .
Biological treatment (via composting) .
Solvent extraction
.
.
.
.
.
.
.
From this evaluation, three potential remedial alternatives were assembled that con-
tained one or more elements from the responses listed above. These alternatives are
described in the following sections.
2.7.1 Alternative 1: No Action
Evaluation of the No Action alternative is required under CERCLA, serving as a com-
mon reference point against which other alternatives can be evaluated.
In Alternative 1, no containment, removal, or treatment of the soil at the Explosives
Washout Lagoons would occur, and no new controls would be implemented to prevent
human exposure. However, existing security provisions that limit public access con-
tinue until such time as the Army vacates the UMDA facility. Some natural chemical
-------
.
Table 4
Summary of Risk-Based Remedial Action Criteria. for
Multiple Pathway Direct Contact Exposure
for the Explosives Washout Lagoons (Site 4)
for Residential and Light Industrial Land Use Scenarios
Contaminant Concentrations (ppm) versus Excess Cancer Risk Levels
Residential Land Use Scenario Industrial Land Use Scenario
1.00E-04 1.00E-05 1.00E-Q6 1.00E-04 1.00E-05 1.00E-06
Analyte
1,3~- TNB
1,3-DNB
2,4,6- TNT 396 40 4.0 837 84 8.4
2,4-DNT 17 1.7 0.17 37 3.7 0.37
HMX
NB
RDX 620 62 6.2 3,250 325 33
Contaminant Concentrations (ppm) versus Hazard Indices
Residential Land Use Scenario Industrial Land Use Scenario
HI = 0.1 HI = 1.0 HI = 10 HI = 0.1 HI = 1.0 HI = 10
Analyte
1,3,5- TNB 0.10 0.96 9.6 0.67 6.7 67
l,3-DNB 0.19 1.9 19 1.3 13 133
2,4,6- TNT 0.95 9.5 95 6.7 67 667
2,4-DNT 1.1 11 114 8.0 80 800
HMX 95 946 9,458 667 6,669 66,687
NB 1.0 10 95 6.7 67 667
RDX 22 217 2,174 572 5,723 57;1.27
l0022E50.SEA
-------
or biological degradation of the explosives IIright occur, although the rate predicted
based on site conditions will be very slow.
This alternative does not meet the Oregon requirement for cleanup to background, or
the lowest levels that are protective and feasible, nor does it achieve protection of
human health and the environment within the guidelines the NCP. The human health
risks presented in Table 3 for future use scenarios are not reduced, and groundwater
degradation can continue.
Alternative 1 requires no time to implement, and involves no capita] or operations and
maintenance (O&M) costs.
2.7.2 . Alternative 2: Excavation, Incineration, and Onsite Disposal
Alternative 2 involves excavation of contaminated soils using conventional construction
equipment, onsite incineration, and replacement of the treated soil in the lagoon exca-
vation. A clean soil cover would be placed over the top, and the area would be graded
and revegetated.' .
Within this alternative, three excavation options are considered:
.
Excavation of all soil with detectable levels of explosives. The excavation
will extend to the water table, and the soil volume will be 32,000 cy
(47,000 tons). This option represents cleanup to background levels.-
.
Excavation of soils containing TNT or RDX concentrations greater than
30 ppm. The average excavation depth will be approximately 5 feet
below the lagoons, and the soil. volume will be about 4,800 cy
(6,800 tons). This is a risk-based option representing removal of soils
. with an excess cancer risk of greater than 7 x 10-0 (industrial use
scenario). .
.
Excavation to a depth of 20 feet below the lagoons. The soil volume will
be 21,000 cy (30,000 tons). This is a non-risk-based option; it represents
a conservative removal of all soil to which direct exposure during future
soil-disturbing activities is likely. Because explosives concentrations are
relatively consistent from 5 feet to the water table, no additional risk
reduction is achieved.
A commercially-available mobile incinerator designed to process 4 tons per hour is
assumed to be used for the 6,800-ton option, and a commercially-avai]able transport-
able incinerator designed to process 20 tons per hour is assumed to be used for larger
volume options.
-------
In this alternative, it is expected that residual explosives concentrations in treated soil
would be below detection levels (less than 1 ppm, with an excess total cancer risk of
less than 1 x 10.0 and HIs of less than 1 for all explosives contaminants) and thus be
protective of human health. This level of treatment has been demonstrated in full-
scale remedial actions conducted at similar sites and would achieve the greatest reduc-
tion in contaminant concentrations of the all the alternatives. Assuming that residual
concentrations below detection levels represent background, only this alternative can
achieve a cleanup to background levels.
Suitable incineration units are available from several vendors. VESTA Technology,
Inc., offers a 4-ton-per-hour unit, and IT Corporation, ENSCO Environmental Services,
and Weston Services, Inc., among others, offer larger units. Rotary kiln incineration of
explosives-contaminated soil has been approved by the Department of Defense Explo-
sives Safety Board. .
Some materials handling might be required for size reduction of larger rocks, but this
effort is expected to be minimal. A treatment area would be developed in close prox-
imity to the lagoons, with concrete and asphalt pads for the incinerator and feed stag-
ing operations. It is estimated that 1 year would be required to develop the site and
prepare bid specifications for the incineration unit. A trial burn would be conducted to
verify the destruction and removal efficiency for the explosives compounds and demon-
strate performance of the air emissions controls. Baghouses would likely be required
to control particulate emissions. Effluent streams from the incinerator would include
gaseous emissions and treated soil and fly ash product. Treated soils and fly ash would
be tested to verify that explosives concentrations met the cleanup criteria before re-
placement in the excavation. Actual incinerator operations would require from 3 to
7 months, depending on the soil volume and incinerator design.
The costs for Alternative 2 and the three excavation options would be as follows:
.
Capital
S-foot excavation: $650,000
20-foot excavation: $1,200,000
Excavation to water table: $1,200,000
.
O&M
S-foat excavation: $3,800,000
20-foot excavation: $7,092,000
Excavation to water table: $12,800,000
-------
.
Present Worth
5-foot excavation: $4,120,000
20-foot excavation: $7,650,000
Excavation to water table: $12,800,000
The following major ARARs are cited for Alternative 2:
0"
.
This alternative would comply with the process descn"bed in the Oregon
Environmental Oeanup Law. Reducing explosives concentrations to
essentially background levels is technically feasible using incineration;
therefore, an excavation of all contaminateg soils combined with
incineration of the excavated soil is evaluated. Because the scope and
cost of such a cleanup might be excessive, scenarios involving more
limited excavations that are stiJ) protective and cost-effective are also
evaluated.
.
This alternative would comply with all state and National Ambient Air
Quality Standards (NAAQS) air emissions ARARs for any remedial
activities, such as excavation and incineration, that result in' airborne
discharges from the site.
.
"This alternative would comply with relevant and appropriate state solid
waste guidelines for incineration units and replacement of incinerated
soil in the excavation. . .
2.7.3 Alternative 3: Excavation, Composting, and Onsite Disposal
Alternative 3, the selected remedy, involves excavation of contaminated soils using
conventional construction equipment, onsite composting, and replacement of the com-
post in the lagoon excavation. A clean soil cOver will be placed over the top, and the
area will be graded and revegetated. .
Within this alternative, two excavation options are considered:
.
Excavation of soils containing TNT or RDX concentrations greater than
30 ppm. The average excavation depth will be approximately 5 feet
below the lagoons, and the soil volume will be about 4,800 cy
(6,800 tons). This is a risk-based option representing removal of soils
with an excess cancer risk of greater than 7 x 1O~ (industrial use
scenario ).
-------
.
.
Excavation to a depth of 20 feet below the lagoons. The soil volume will
be 21.,000 cy (30,000 tons). This is a non-risk-based option; it represents
a conservative removal of all soil to which direct exposure during future
soil-disturbing activities is likely. Because explosives concentrations are
comparable at 5 feet and at 20 feet, no additional risk reduction is
achieved.
An excavation of all contaminated soil (excavation to the water table), one of the op-
tions in Alternative 2, is not considered in Alternative 3. Composting technology
cannot achieve background concentrations of explosives, and therefore it is not reason-
able to combine treatment via composting with an excavation to the water table.
A facility designed to accept 100 cy of soil per week is assumed for the 6,800-ton op-
tion, while a facility designed to accept 200 cy per week is assumed for a volume of
30,000 tons. .
In this alternative, it is expected that residual explosives concentrations will be reduced
by 97 to 99 percent. The remedial action criteria are set at TNT and RDX concentra-
tions of 30 ppm or less each. These levels correspond to an excess cancer risk under
the industrial use scenario of 7 x 10-6 (assuming that 2,4-DNT is also present, at an
average concentration of 1 ppm) and are within the range of acceptable cancer risks.
The HIs for all explosives contaminants except TNB will be less than 1; the HI for
TNB could be as high as 7, assuming no degradation of that explosive. This level of
treatment has been demonstrated in site-specific pilot-scale treatability and
optimization studies conducted at UMDA.
Compo sting is a well-known technology for the treatment of solid wastes, such as mu-
nicipal wastewater treatment sludges and yard debris, whereby microbial populations
degrade organic materials. Its application to explosives-contaminated soils is innova-
tive. Composting requires conventional technology and can be readily implemented
using commercially available equipment and materials.
Three different composting methods were evaluated for treating the lagoon soils:
Mechanically-Agitated In-Vessel (MAN) composting, static pile composting, and
windrow composting. They differ in technical complexity and the degree to which they
control temperature, moisture content, and. aeration. Using MAIV composting, the soil
is placed in a reactor vessel and agitated periodically. In static pile composting, the
soil is composted in open piles without any mixing. With windrow composting, the soil
is formed into elongated piles (windrows) that are turned regularly using a windrow
machine. . Site-specific studies have demonstrated that mixing, whether in an MAIV or
in windrows, is more effective for reducing explosives concentrations than composting
in statIc piles. Both MAJ.V and windrow composting are considered under this
alternative.
-------
.
The soil is mixed with suitable organic amendments to enhance biological activity prior
to composting. Larger rocks might require screening and separate handling; they can
be washed, and the washwater added to the compost mixture. The single effluent
stream is the final compost. It will be tested to verify that explosives concentrations
meet the remedial action criteria before replacement in the excavation. Approximately
1 year will be required to develop the site and prepare bid specifications for the com-
posting facility. It is estimated that another year will be required to compost 6,800 tons
of soil, and 2 years for 30,000 tons.
The costs for Alternative 3 (MAIV and windrow) and the two excavation volume op-
tions are as follows:
.
Capital
.:
5-foot excavation (MAIV): $1,480,000
20-foot excavation (MAIV): $2,314,000
5-foot excavation (windrow): $880,000
20-foot excavation (windrow): $1,784,000
J~
.
O&M
-,
..,
5-foot excavation (MAIV): $1,783,000
20-foot excavation (MAIV): $7,599,000
5-foot excavation (windrow): $1,084,000
20-foot excavation (windrow): $4,399,000
."
...,
.
. Present Worth
.; ,',.",
5-foot excavation (MAIV): $3,100,000
20-foot excavation (MAIV): $8,200,000
5-foot excavation (windrow): $1,870,000
20-foot excavation (windrow): $5,590,000
The following major ARARs are cited for Alternative 3:
.
This alternative complies with the process descn"bed in the Oregon Envi-
ronmental Qeanup Law. Qeanup to background levels using compost-
ing is not technically feasible; such a cleanup can only be achieved under
Alternative 2 using incineration. However, Alternative 3 does present a
cleanup option that is protective and feasible. .
.
This alternativ~ will meet relevant and appropriate state solid waste
guidelines for compost units and management of the compost.
-------
,
2.8
SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
This section and Tables 5 and 6 summarize the relative performance of each of the
three alternatives with respect to the nine CERLCA evaluation criteria.
2.8.1 Threshold Criteria
Overall protection of human health and the environment.' Alternative 1, No Action,
provides no protection for future users of the site or for the environment. Alterna-
tives 2 and 3, Incineration and Composting, both provide overall protection of human
health in accordance with the NCP.
First, both provide a clean soil cover, minimizing direct contact with underlying treated
soils that might contain residual contaminants. In addition, both reduce the excess
cancer risk in treated soils to within the range of 1 x 10-4 to 1 X 10-0 (industrial use
scenario) and reduce concentrations of systemic toxicants to levels at which no adverse
noncarcinogenic health effects would be expected, considering factOrs related to uncer-
tainty.Alternative 2 is somewhat more protective than the selected remedy, Alterna-
tive 3. Alternative 2 reduces the excess cancer risk to less than 1 x 10-0 versus 7 x 10-0
for Alternative 3 (industrial use scenario). Alternative 2, Incineration, will reduce the
noncarcinogenic HI in the treated soil to less than 1 for each explosive. Alternative 3,
Composting, will reduce the HI of each explosive except TNB to less than 1. Under
Alternative 3, the HI for TNB could be as high as 7, assuming that it is not degraded
by composting. (By analogy to other explosives evaluated, substantial degradation of
TNB is expected, but the extent has not been quantified.) However, the uncertainty
factor for TNB is 10,000, three orders of magnitude greater than the HI. Considering
this conservative uncertainty, no adverse noncarcinogenic health effects are expected in
Alternative 3.
Alternatives 2 and 3 both reduce the plant stress associated with high concentrations of
explosives. Residual contamination in the treated soil resulting in Alternative 3 could
result in some minor growth retardation, although this will be minimized by the clean
soil cover.
An excavation depth based on achieving TNT and RDX concentrations of 30 ppm
each provides the best balance of net risk reduction and cost-effectiveness. There is a
clear demarcation in the soil contamination profile (at a depth of about 5 feet)
between concentrations of TNT and RDX greater and less than 30 ppm. Between
5 feet and the groundwater, TNT and RDX concentrations are consistently in the
10 to 30 ppm range. Therefore, an excavation between a depth of 5 feet and the
groundwater does not result in additional risk reduction.
Achievement of ARARs. Alternative 1 does not comply with ARARs, whereas both
Alternatives 2 and 3 comply with all ARARs.
-------
Table 5
Comparative Evaluation of Alternatives
IoN
N
Alternatives 2 and 3 provide overall
protection of human health and the
environment in accordance with the
NCP by rcducir~t the excess cancer
risk to < 1 x 10 and 7.2 x 10-6,
respectively (industrial use scenario),
and noncancer risk to levels that are
protective, taking into account factors
related to uncertainty. Both
alternatives significantly reduce plant
stress associated with very high
explosives concentrations; some minor
reduction in growth height may still
be obselVed in Alternative 3. Aller-
native 1 provides no protection for
future users of the site, does not
'enhance protection of the
environment, and is not addressed
further in this table.
l0022E16.SEA
Alternatives 2 and 3
comply with all
ARARs. In accor-
dance with state
requirements for
remedial actions, the
risk reduction benefits
for variations on each
alternative are shown
as a function of cost.
Long-term effective-
ness is achieved in
Alternative 2 by the
permanent destruction
of 99.99 percent of
contaminants. Al-
ternative 3 achieves
long-term protection
by degrading contami-
nants by 97 to
99 percent.
Excavation to 5 feet
below the lagoons
reduces excess cancer
risk by about 99.8 per-
cent from initial
levels. This increases
to 99.9 percent at 20
feet and 100 percent
at 47 feet.
Both Alternatives 2
and 3 reduce contami-
nant concentrations in
excavated soils, there-
by reducing toxicity.
Alternative 2 reduces
toxicity by
>99.99 percent.
Alternative 3 reduces
toxicity by 88 to
98 percent.
Both Alternatives 2
and 3 use appropriate
controls to provide
near-term protection
of the public, onsite
workers, and the envi-
ronment during
remedial activities.
Alternative ~ could be
implemented and
completed within
15 to 19 months.
Alternative 3 could be
implemented and
completed within
20 to 36 months.
"
Implementability of
Alternative 2 has been
demonstrated for
similar contaminants
at other sites.
Alternative 3 is
innovative, but sup-
ported by site-specific
treatability studies.
There appear to be no
obstacles to obtaining
necessary materials
and agency approval.
Costs (or a 47-foot
excavation with
treatment by
incineration
(Alternative 2)
( cleanup-to-
background) arc
$14 million. For
other excavation
depths, Alternative 3
is less expensive,
especially for low
volume remediation
(e.g., for a 5-foot
excavation, costs arc
$2 million for com-
posting versus
$4 million for
-------
IJ.)
IJ.)
Table 6
Cost and Effectiveness of Alternatives as a Function of Excavation Depth
Excess Cancer Risk Following Remediation-
Excess Cancer Risk Prior Soli Remaining Below
to Remediation- Excavatedffreated Soli Excavation Depthd
Cost
Industrial Residential Industrial Residential Industrial Residential Total (present
Mass Use Use Use Use Use Use Cost worth,
Alternative (tons) Scenario Scenario Scenario Scenario Scenario Scenario ($000) $000)
No Action NA 4.7 x 1003 1.0 X 1002 NA NA 4.7 x 1003 1.0 X 1002 0
Incineration
2-foot excavation 3,700 4.7 x 1003 1.0 X 1002 <1 x 10-6 < 1 x 10-6 8.0 x 10-5 2.1 x 10-4 2,730 2,540
5-foot excavation 6,800 4.7 x 10-3 1.0 x 10-2 < 1 X 1006 <1 x 10-6 7.2 x 10-6 1.8 x 10-5 4,470 4,120
20-foot excavation 30,000 4.7 x 10-3 1.0 X 10-2 < 1 X 10-6 <1 x 1006 7.2 x 10-6 1.8 x 1005 8,290 7,650
47-foot excavationb 47,000 4.7, x 10-3 1.0 X 10-2 <1 x 10-6 < 1 X 10-6 < 1 x 10-6 <1 x 10-6 14,000 12,800
Composting-Windrows 4.7 x 1003' 1.0 x 10-2 7.2 x 10-6 1.8 x 10-5 8.0 x 1005 2.1 X 10-4
2.foot excavation 3,700 1,430 1,370
5-foot excavation 6,800 4.7 x 10-3 1.0 X 1002 7.2 X 10-6 1.8 x 10-5 7.2 X 1006 1.8 x 10;5 1,960 1,870
20-foot excavation 30,000 4.7 x 10-3 , 1.0 X 10-2 7.2 X 10-6 1.8 x 10-5 7.2 X 10-6 1.8 x 10-5 6,180 5,590
47-foot excavationC NA 4.7 x 1003 1.0 X 10-2 NA NA NA NA NA NA
Composting-.MAIV 4.7 x 10-3 1.0 X 1002 <7.2 X 1006 < 1.8 x 1005 8.0 X 10-5 2.1 X 10-4
2-foot excavation 3,700 2,410 2,320
5-foot excavation 6,800 4.7 x 1003 1.0 x 10-2 <7.2 x 10-6 < 1.8 x 1005 7.2 x 1006 1.8 x 10-5 3,270 3,100
20-foot excavation 30,000 4.7 x 10-3 1.0 x 10-2 <7.2 x 10"6 < 1.8 x 1005 7.2 x' 1006 1.8 x 10"5 9,910 8,200
47-foot excavationC NA 4.7 x 10-3 1.0 x 10-2 NA NA NA NA NA NA
BRisk based on direct contact with soil: ingestion, inhalation, d'ermal contact.
t>-rhls scenario reflects cleanup to background. All contaminated soil would be treated.
cA combination of composting and a 47.foot excavation was not evaluated. The deep excavation is intended to reflect cleanup to background
and cannot be achieved by composting. .
dRlsk calculations based on average TNT, RDX, and 2,4-DNT concentrations measured at Indicated depth.
NA = Not applicable to this alternative.
cy = Cubic yards.
-------
.
There are no federal or state explosives-specific soil cleanup standards. In their ab-
sence, the most notable ARAR is the Oregon Environmental Cleanup Law. This law
specifies a remediation process that requires cleanup to background levels or, if that is
not feasible, cleanup to levels that are protective and feasible. Cleanup to background
was evaluated in the feasibility study as an option under Alternative 2, whereby all soils
with detectable levels of explosives would be incinerated to concentrations below
detection limits. The selected remedy, Alternative 3, cannot reduce concentrations to .
below detection limits. Both Alternatives 2 and 3 were then evaluated in terms of
achieving the lowest cleanup levels that would be protective and feasible. Health-
based protective levels can be achieved under either alternative, but the selected
remedy, Alternative 3, is significantly more cost-effective (i.e., "feasible" as defined by
Oregon law).
2.8.2 Primary Balancing Criteria.
Long-tenn effectiveness. In Alternative 1, No Action, there is virtually no long-term
risk reduction anc;l therefore the alternative does not demonstrate long-term effective-
ness. The effectiveness of Alternative 2, Incineration, has been proven in full-scale
remedial actions at sites with similar contamination. Incineration at those sites has
resulted in the permanent destruction of 99.99 percent or greater of the explosives.
The effectiveness of Alternative 3, Composting, has been demonstrated in site-specific
pilot-scale treatability studies. In those studies, composting has degraded and immobi-
lized 97 to greater than 99 percent of the explosives, and is therefore somewhat less
effective than incineration.
Both Alternatives 2 and 3 result in treatment residuals, incinerated soil in Alternative 2
and com posted soil in Alternative 3. .
Reduction in toxicity, mobility, or volume of contaminants. Alternative 1 does not
reduce the toxicity, mobility, and volume of contaminants. Both Alternatives 2 and 3
reduce the contaminant toxicity, mobility, and volume by a magnitude assumed to be
comparable to the destruction of contaminants, or 99.99 percent. Alternative 3 reduces
soil toxicity by 88 to 98 percent based in laboratory tests comparing the toxicity of con-
taminated soil and composted soil.
Short-tenn effectiveness. Alternative 1 is effective in the near-term, since public access
to the UMDA installation is currently restricted and no military personnel are active in
the vicinity of the Explosives Washout Lagoons. Both Alternatives 2 and 3 use ap-
propriate controls to provide near-term protection of onsite workers, the public, and
the environment during remedial activities.
Alternative 1 could be implemented immediately. Alternative 2 could be implemented
and completed in 15 to 19 months. Alternative 3 could be implemented and com-
. pleted in 24 to 36 months.
-------
Implementability. There are substantial administrative obstacles to implementing Alter-
native 1, since this alternative does not meet state or EP A cleanup objectives.
Both Alternatives 2 and 3 can be readily implemented. A number of vendors are
available for implementation of onsite incineration as descnbed in Alternative 2. Fur-
- ther,- rotary-kiln incineration has been thoroughly tested and has a well-documented
history of successful performance at sites with explosives compounds in soils. Selected
Alternative 3 is an innovative application of an existing technology, and site-specific
treatability studies have been completed. A final optimization study is nearing comple-
tion and will allow implementation of the remedy in about 1 year. The equipment and
materials required to implement Alternative 3 are readily available from local sources
and national vendors. .
Cost. The estimated capital, O&M, and present worth costs for each remedial alterna-
tive are as follows:
-.
.
Alternative 1
Capital: $0
O&M: $0
Present Worth: $0
.
Alternative 2
(Excavation to background levels)
Capital: $1,200,000
O&M: $12,800,000
Present Worth: $12,800,000
.
Alternative 2
(Excavation to TNT and RDX concentrations of 30 ppm)
Capital: $650,000
O&M: $3,800,000
Present Worth: $4,120,000
.
Alternative 3 (using windrows) .
(Excavation to TNT and RDX concentrations of 30 ppm)
Capital: $880,000
O&M: $1,084,000
Present Worth: $1,870,000
-------
.
2.8.3 Modifying Criteria
State acceptance. The State of Oregon concurs with the Army and EP A in the selec-
tion of Alternative 3 and excavation criteria of 30 ppm TNT and RDX. In addition,
the state is satisfied that the state's remedial action process was followed in evaluating
- remedial action alternatives for the Explosives Washout Lagoons Soils Operable Unit.
Public acceptance. Based on the absence of any negative comments from the public
and the support given in the single formal comment received, the public supports the
selection of Alternative 3.
2.9
SELECTED REMEDY
The selected remedy to clean up the soil contamination associated with the UMDA
Explosives Washout Lagoons is Alternative 3: Excavation, -Composting, and Onsite
Disposal, using excavation and treatment criteria of 30 ppm each of TNT and RDX
and windrow composting. The treated soils will be backfilled into the excavation, cov-
ered with clean soil, and revegetated. This alternative was selected because it is pro-
tective, feasible, and cost-effective.
The selected treatment technology is bioremediation via composting. It is an
innovative application of a proven technology, backed by site-specific treatability
studies. Approximately one year will be required for site development and necessary
procurements, with an actual composting period estimated at one additional year. The
estimated present worth cost of Alternative 3 is $1,870,000. The estimated volume of
soil to be removed and treated is 4,800 ey.
The major components of the selected remedy include the following:
.
. Construction of a roadway between the lagoons and the composting
facility to transport excavated and treated soils
.
Development of the composting facility onsite, including clearing and
grubbing, grading, and construction of asphalt pads and erection of
greenhouse-type structures
.
Excavation of soils exceeding TNT or RDX concentrations of 30 ppm;
excavation wi11 include appropriate hazards monitoring and dust controls
.
Mixing contaminated soils with organic amendments (e.g., vegetable
waste, straw, manure) as appropriate and forming the mixture into
windrows .
.
Regularly turning the windrows with a windrow machine
-------
. .
.
Testing the finished compost for explosives
.
Backfilling the excavation with compost, covering with approximately
2 feet of clean soil obtained from either onsite or offsite, grading, and
revegetating
Alternative 3 will attain the following remediation goals:
2.10
.
Soils will be excavated to the cleanup criteria of 30 ppm each of TNT
and RDX. For the soils that remain in place (i.e., those soils below the
excavation depth), this corresponds to attainment of. a 7 x 10-0
carcinogenic risk level. This includes a contribution of 3 x 10-0 from 2,4-
DNT at an average concentration of 1 ppm. . .-
.
Excavated soils will be treated to the cleanup criteria of 30 ppm each of
TNT and RDX. This corresponds to attainment of a total 7 x 10-0 car-
cinogenic risk level. This includes an assumed contribution of 3 x 10-0
from 2,4-DNT at an average concent~ation of 1 ppm. (2,4-DNT has not
been detected in the upper 6 to 8 feet of soil, so this contn"bution is
conservative.) .
STATUTORY DETERMINATIONS
The selected remedy satisfies the requirements under Section 121 of CERCLA to:
.
Protect human health and the environment
Comply with ARARs
Be cost-effective
. .
Utilize permanent solutions and alternative treatment technologies or
resource recovery technologies to the maximum extent practicable
Satisfy the preference for treatment as a principal element
.
.
.
.
2.10.1 Protection of Human Health and the Environment
The selected remedy, Alternative 3, will reduce risks posed to future users of the Ex-
plosives Washout Lagoons site through treatment of excavated soils via composting,
followed by onsite disposal of the treated soils and provision of a 2-foot cover of clean
.soil. The overlying clean soil cover will minimize direct contact with treated soils con-
taining residual explosives. In .the event that there is contact with the underlying
treated soil, the explosives will have been degraded and immobilized, with the following
residual risks:
-------
. .
.
Human health risks associated with e~osure to carcinogens in the
treated. soil and in soil that remains in place (i.e., soil below the excav-
ation depth) will be reduced to within the NCP's acceptable range of
1 x 10-4 to 1 x 10.0 (both industrial and residential use scenarios).
.
No adverse noncarcinogenic health effects are anticipated, considering
the residual explosives concentrations in the treated soil and the
conservatism incorporated into the HI calculations. For each of the
explosives except TNB, the HIs associated with the treated soil
concentrations will be less than 1 (industrial use scenario). The HI for
TNB could be as high as 7, assuming no credit for degradation via
composting. (By analogy to other explosives evaluated during the pilot
studies, substantial degradation is expected, but'tIfe degree has not been
quantified.) However, the uncertainty factor for TNB is 10,000, three
orders of magnitude greater than the HI. Considering this uncertainty as
required by the NCP, no adverse noncarcinogenic health effects are
expected.
.
Environmental protection is achieved by reducing explosives concentra-
tions and associated plant stress significantly and providing a clean soil
layer to support a vegetative cover.
.
This remedy is expected to be consistent with future remediation of the
groundwater. It provides a substantial reduction in near-surface soil
concentrations and a cover of clean soil. In combination with the low
precipitation and high evaporation rates in the region, negligible
leaching of residual contaminants is expected.
No unacceptable short-term risks or cross-media impacts will be caused by implement-
ation of Alternative 3. During remediation, adequate protection will be provided to
the community and the environment by controlling dust generated during materials
handling operations. In addition, workers will be provided with personal protective
equipment and air monitoring during all phases of remediation. .
2.10.2 Compliance With ARARs
The discussion below addresses compliance of the selected remedy with chemical-
specific, location-specific, and action-specific ARARs.
Chemical-Specific ARARs. Under RCRA (40 CFR 261), wastewater treatment sludge
from the manufacturing and processing of explosives is considered a listed waste due to
explosive reactivity and is assigned EP A Hazardous Waste Number K044. Red/pink
water from TNT operations is also considered a listed waste due to explosive reactivity
and is assigned EPA Hazardous Waste Number K047. However, EPA's background
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listing document supporting these designations explicitly lists wastes derived from the
manufacturing, load~g, assembling, and packing of explosives, not removal from muni-
tions. Therefore, neither the wastewater discharged to the lagoons nor the contam-
inated soil are specific listed wastes, and RCRA and its associated regulations are not
applicable. Furthermore, although the soil contains constituents similar to those found
in the listed wastes, explosives concentrations in the soil are well below the minimum
concentrations necessary for explosive reactivity, the sole characteristic for which the
K044 andK047 wastes were listed. Therefore, while the RCRA listings might be rele-
vant to the contaminated soil, they are not appropriate since the soil does not exhibit
the characteristic of concern.
At . present, there are no chemical-specific federal or state regulations that specify
action or cleanup levels for explosives contaminants in soil. . --
The state has implemented the Oregon Environmental Cleanup Rules (OAR 340-122),
which specify generic cleanup standards and which the. state has determined are
ARARs for the UMDA Explosives Washout Lagoons. In summary, the regulations -
state that in the event of a release of a hazardous substance, cleanup shall be to
.background or, if that is not feasible, to the lowest level that is protective and feasible.
A cleanup-to-background scenario was evaluated under Alternative 2 but determined
not to be feasible based on a cost seven times greater than other scenarios that
provided adequate protection. A cost-benefit analysis of remediation options was then
conducted, resulting in the selection of Alternative 3 as the remedy achieving the
lowest levels that are protective and feasible (see Section 2.10.3).
Location-Specific ARARs. No location-specific ARARs are identified for this alterna-
tive. Although areas of the UMDA installation provide critical habitat for threatened
or endangered species, no activities at the Explosives Washout lagoons are expected to
impact those habitats.
Action-Specific ARARs. The treatment and disposal of the contaminated soil and
compost will comply with the relevant and appropriate sections of the Oregon Solid
Waste Management Regulations (OAR 340-61-050). These include provisions for
drainage control, odor control, and fire protection at composting facilities, -and prepa-
ration of a plan describing the final disposition of the compost.
2.10.3 Cost-Effectiveness
The selected remedy provides overall effectiveness proportionate to its costs. Alterna-
tive 3 provides 97-99 percent contaminant reduction at a cost of $1.9 million.
Alternative 3 is somewhat more protective, providing- 99.9 percent contaminant
reduction, but at a cost of $4-.1 million. Therefore, Alternative 2 is not cost-effective,
. since its incremental increase in cost is disproportionate to its incremental increase in
protection.
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2.10.4 Utilization of Permanent Solutions and Alternative Treatment Technologies or
Resource Recovery Technologies to the MaXimum Extent Practicable
"
The selected remedy is a permanent solution that provides the best balance of trade-
offs among the alternatives. Alternative 1 fails to meet the threshold criteria of overall
protection and compliance with ARARs and is thus clearly unacceptable. Both Alter-
natives 2 and 3 meet the threshold criteria. They are also both comparable in terms of
short-term effe"ctiveness and implementability. They differ in terms of degree or
protectiveness afforded and cost'. Alternative 2 provides the greatest degree of
protection, reducing explosives concentrations by an estimated >99.99 percent, versus
97 to > 99 percent for Alternative 3. While this makes Alternative 2 the best in terms
of.long-term effectiveness and reduction of toxicity, Alternative 3 achieves acceptable
protection levels and satisfies those criteria adequately, at half-the cost. In addition, it
provides a demonstration of an innovative technology.
The support of the state and community in the evaluation process and the selection of
Alternative 3 further justify the selection of Alternative 3.
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 statutory preference for treatment is satisfied by using biological treatment via
compo sting as the primary means for addressing and degrading the explosives
contaminants.
2.11
DOCUMENTATION OF SIGNIFICANT CHANGES
The selected remedy was the preferred alternative presented in the Proposed Plan. No
changes have. been made.
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SECTION 3
RESPONSIVENESS SUMMARY
The final component of the ROD is the Responsiveness Summary, which serves two
purposes. First, it provides the agency decision makers with information about commu-
nity 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 a 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 demilitariza-
tion pi"ogram, which is' separate from CERCLA remediation programs, has drawn
substantial comment and concern.
As part of the installation's community relations program, the UMDA command as-
sembled in 1988 a TRC composed of elected and appointed officials and other
interested citizens from the surrounding communities. Quarterly meetings provide an
opportunity 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 supplemental investigation and feasibility study for the Explosives
Washout Lagoons Soils Operable Unit, one on October 15, 1991, and the other on
February 19, 1992. 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. The response received from the TRC was positive;
the members showed particular interest in and support for the composting alternative.
Notice of the public comment period, public meeting, and availability of the Proposed
Plan was published in the Hermiston Herald, the Tri-City Herald, and the East Oregon-
ian in April 1992.
The Feasibility Study and Proposed Plan for the Explosives Washout Lago'ons Soils
Operable Unit were released to the public on April 27, 1992. The public comment
period started on that date and ended on May 27, 1992. The documents constituting
the administrative record were made available to the public at the following locations:
UMDA Building 1, Hermiston, Oregon; the Hermiston Public Library, Hermiston,
Oregon; and the EP A office in Portland, Oregon.
A public meeting was held at Armand Larive Junior High School, Hermiston, Oregon,
on May 5, 1992, to inform the public of the preferred alternative and to seek public
comments. At this meeting, representatives from UMDA, USA THAMA, EP A,
ODEQ, and CH2M HILL presented the proposed remedy. Approximately 20 persons
from the public and media attended the meeting. Questions asked during the informal
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question and answer period requested more detail regarding excavation criteria, the
treatability studies, .implementation methods, and costs associated with compo sting.
Only one formal comment was received during the public meeting. The speaker was a
former UMDA employee and current community leader. He stated that after reading
the Proposed Plan and listening to the presentations, he thought the community .could
be assured that the Army was interested in protecting the environment and the people
living there. No response was required.
No other comments, either verbal or written, were received by UMDA, EP A, or
ODEQ during the public comment period.
lOO228DASEA
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Oregor
September 9, 1992
DEPARTMENT or
ENVIRONMENTA l
QUALITY
. Ms. Dana Rassmussen
. Regional Administrator
U.S. Environmental Protection Agency
1200 Sixth Ave.
Seattle, WA 98101 .
Re:
Umatilla Depot ActivitY
Lagoon Soils Operable Unit
Record of Decision
Dear Ms. Rassmussen:
The Oregon Department of Environmental Quality (DEQ) has reviewed the draft
Record of Decision, for the Explosives Washout Lagoons Operable Unit at the U.S.
Army's Umatilla Depot Activity. I am pleased to advise you that DEQ concurs with
the remedy recommended by EPA and the Army (i.e., biological treatment of the
contaminated soils). I find that this alternative is protective, and to the. maximum
extent practicable is cost effective, uses permanent solutions and alternative
technologies, is effective and implementable. Accordingly, it satisfies the
requirements of ORS 465.315, and OAR 340-122-040 and 090. .
It is understood that this decision is for the lagoon soils only, and that
contaminated groundwater beneath the lagoons will be dealt with as a separate
operable unit. .
The Department looks forward to the prompt implementation of the selected
remedy, and to continued progress with EPA and the Army toward the thorough
cleanup of this facility. .
Sincerely,
~~wo..-...
Fred Hansen
Director'
WD:m
SITE\SM35\SM4658
cc: Lewis D. Walker, 000
LTC. William McCune, UMDA
Harry Craig, EPA-OOO
~
.
,.,
811 SW Sixth Avenue
Portland, OR 972()..1-13'-
(503) 229-5696
TDD (503) 229-6993
DEQ-I
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