EPA/ROD/R10-94/107
March 1995
EPA Superfund
Record of Decision:
Bangor Naval Submarine Base
(O.U. 2) (Site F), Silverdale, WA
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Declaration of the Record of Decision,
Decision Summary, and
Responsiveness Summary
for
FmalRemedmlAcuon
Naval Submarine Base Bangor Site F
(Operable Unit 2)
Silverdale, Washington
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DECLARATION OF
THE RECORD OF DECISION
,
SITE NAME AND LOCATION
Naval Submarine Base Bangor Site F (Operable Unit 2)
Silverdale, Washington
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected remedial action for Site F
(Operable Unit 2) at the Naval Submarine Base (SUBASE), Bangor in
. Silverdale, Washington, chosen in accordance with the Comprehensive
Environmental Response, Compensation, and Liability Act (CERCLA), as
amended by the Superfund Amendments and Reauthorization Act (SARA),
and, to the extent' practicable, the National Oil and Hazaidous Substances
Pollution Control Contingency Plan (NCP). This decision is based on the
administrative record for the site.
The remedy was selected by the U.S. Navy as lead agency, and the.D.S.
Environmental Protection Agency (EP A). The State of Washington
Department of Ecology (Ecology) concurs with the selected remedy.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from the site, if not
addressed by implementing the response action selected in this Record of
Decision (ROD), may present an imminent and substantial endangerment to
public health, welfare, or the environment.
DESCRIPTION OF THE SELECTED REMEDY
The selected remedy is the only response action planned for Site F
(Operable Unit 2). This action addresses contaminated soil and
contaminated groundwater. The selected remedy will consist of the
following actions:
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Soil Remediation
~
. Excavate soils to a depth of 15 feet which exceed State Model Toxics
Control Act (MTCA; Chapter 173-340 WAC) residential contact
cleanup levels for ordnance (33 mg/kg TNT; 1.5 mg/kg DNT; and 9.1
mg/kg RDX). The volume of soil to be excavated is estimated to be
approximately 1,000 cubic yards;
"
. Treat the excavated soils by adding organic amendment under
controlled conditions to facilitate and enhance biological degradation of
ordnance compounds in the soils;
. Monitor the effectiveness of the soil treatment process throughout
implementation to ensure its effective operation. Allowances will be
made for operational adjustments to optimize reductions in ordnance
concentrations in the soil. Soil treatment will reduce ordnance
concentrations in the amended soil to the extent possible and, at a
minimum, to below MTCA soil cleanup levels for direct contact
exposure;
. Upon completion of the biological soil treatment, use the treated
soil/amendment mixture to rul and regrade the Site F excavation and
overflow ditch;
. Install an infiltration barrier over all soils with concentrations above
soil cleanup levels for protection of groundwater; and
. Monitor the condition of the infiltration barrier as needed to ensure its
structural integrity.
Groundwater Remediation
. Modify the existing Site F Interim Remedial Action (IRA) groundwater
extraction, treatment, and reintroduction system by adding additional
extraction wells to enhance, to the maximum extent practicable, the
removal of constituents from the Shallow Aquifer at Site F;
. Treat extracted groundwater using granular activated carbon (GAC) for
removal of ordnance, and ion exchange as necessary for nitrate
removal, to meet MTCA groundwater cleanup levels prior to its
reintroduction to the Shallow Aquifer;
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. Permanent destruction of the ordnance compounds will be achieved
during thermal regeneration of the granular activated carbon at a
permitted off-site facility;
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. Return the treated water to the SUBASE, Bangor, Shallow Aquifer by
means of reintroduction wells;
..
. Monitor the effectiveness of the groundwater remediation program and
make appropriate operational adjustments to optimize, to the maximum
extent practical, the removal of constituents from the Shallow Aquifer
at Site F; and
. Initiate a formal review (by the Navy, EP A, and Ecology, as defmed in
Section 19 of the Federal Facilities Agreement) of the groundwater
remediation system operation after one of the following performance
evaluation criteria, as defmed in this ROD, is met:
(1)
Groundwater cleanup levels are achieved for all constituents of
concern in the Shallow Aquifer at Site F; or
(2)
No statistically significant change in constituent concentrations
is observed, in monitoring wells at Site F which exceed
groundwater cleanup levels, after reasonable system
enhancements and modifications have been implemented; or
(3)
The rates of constituent concentration reductions in the Shallow
Aquifer at Site F indicate that the cost of continued system
operation is substantial and disproportionate relative to the
incremental degree of environmental protection.
Based on this review, the Navy and EPA, in consultation with Ecology,
will determine whether system shutdown, continued system operation, or
other remedial response is warranted.
. If the Navy and EP A, in consultation with Ecology, determine that
continued groundwater remediation system operation is technically
infeasible or impracticable, institutional controls and water quality
monitoring within the Shallow Aquifer will be implemented as required
by EP A and Ecology to protect human health and the environment until
cleanup levels are achieved.
STATUTORY DETERMINATIONS
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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 or resource
recovery technologies to the extent practicable and satisfies the statutory
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preference for remedies that employ treatment that reduces toxicity,
mobility, or volume as a principal element. Because this remedy may
result in hazardous substances remaining on site above health-based levels
a review will be conducted within a 5-year period, at a minimum, or as
required based on the perfonnance evaluation criteria contained herein, to
ensure that the remedy continues to provide adequate protection of human
health and the environment.
~~1> ~ J
Captain Ernest Lockwood
SUBASE, Bangor Commanding Officer
United States Navy
~(/?4
, I
Date
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Signature Sheet for the foregoing SUBASE, Bangor, Site F, Remedial
Action, Record of Decision between the United States Navy and the United
States Environmental Protection Agency, with concurrence by the
Washington State Department of Ecology.
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Cf:.L~1! £I ~/lJt
LA... Ch ck Clarke
/r~ Regional Administrator, Region 10
United States Environmental Protection Agency
9 -;;. "5- 7 V
Date
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Signature Sheet for the foregoing SUBASE. Bangor. Site F. Remedial
Action. Record of Decision between the United States Navy and the United
States Enviromnental Protection Agency. with concurrence by the
Washington State Depanment of Ecology.
. ,
/ . <... .
(i.../c K [" ~ I'J:. ).
Carol Kraege. Ac ing Progra Manager
Toxics Clean-Up Program
Washington State Depanment of Ecology
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CONTENTS
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Page
. ACRONYMS AND ABBREVIATIONS iv
1.0 INTRODUCTION 1
2.0 SITE NAME, LOCATION, AND DESCRIPTION 1
3.0 SITE HISTORY AND ENFORCEMENT ACTIONS 2
4.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION 4
5.0 SCOPE AND ROLE OF OPERABLE UNITS 5
6.0 SUMMARY OF SITE CHARACTERISTICS 6
6.1 Site Hydrogeologic Conditions 6
6.2 Site Waste Constituents 8
7.0 SUMMARY OF SITE RISKS 11
7.1 Human Health Risks 11
7.2 Ecological Risk Evaluation 13
7.3 Needfor Remedial Action 14
8.0 CLEANUP STANDARDS 14
8.1 Soil 15
8.2 Groundwater 16
8.3 Surface Water 16
9.0 DESCRIPTION AND COMPARISON OF ALTERNATIVES 16
9.1 Soil Remediation Alternatives 16
9.2 Groundwater Remediation Alternatives 20
10.0 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES 23
10.1 Evaluation of Soil Remediation Alternatives by Criteria 24
.. 10.2 Evaluation of Groundwater Remediation Alternatives by Criteria 27
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CONTENTS (Continued)
11.0 THE SELECTED REMEDY
11.1 Soil Remedilltion
11.2 Groundwater Remedilltion
11.3 WeU Deco'!""issioning .
11.4 Groundwater Remedial Action Measures and Goals
11.5 Effectiveness of Treatment Technology
11.6 Groundwater Remediation Perfomumce Evaluation Criteria
12.0 STATUTORY DETERMINATIONS
12.1 Protection of Human Health and the Environment
12.2 Compliance with Applicable or Relevant and Appropriate Requirements
12.3 Cost Effectiveness
12.4 UtiliZJJtion of Pemument Solutions and Alternative Treatment Technologies or
Resource Recovery Technologies to the Maximum Extent Practicable
12.5 Preference for Treatment as Principal Element
13.0 DOCUMENTATION OF NO SIGNIFICANT CHANGES
TABLES
1 Summary of Chemicals of Concern
2 Basis for Selecting Exposure Pathways for Quantitative Risk Assessment
3 Inhalation of Chemicals in Air by Potential Residents
4 Ingestion of Chemicals in Soil by Potential Residents
5 Dermal Contact and Subsequent Absorption of Chemicals in Soil by Potential
Residents
6 Ingestion of Chemicals in Drinking Water by Potential Residents
7 Dermal Absorption of Chemicals in Water by Potential Residents
8 Ingestion of Chemicals in Fish/Shellfish by Potential Recreational Users
9 Fish Bioconcentration Factors for Chemicals of Potential Concern
10 Reference Doses for Chemicals of Potential Concern
11 Slope Factors for Chemicals of Potential Concern
12 Calculated Hazard Quotients for Site F Baseline Exposure Assumptions
13 Calculated Lifetime Cancer Risks for Site F Baseline Exposure Assumptions
14 Summary of Assumptions and Uncertainties in the Baseline Human Health Risk
Asse$sment
15 Summary of Cleanup Levels for Site F
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29
30
32
32
33
34
37
37
37
40
40
41
41
43
44
45
46
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48
49
50
51
52
53
54
55
56 ..
59
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CONTENTS (Continued)
Page
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FIGURES
1 Generalized Regional Map
2 Site F Historical Features Map
3 Monitoring Well Location Map
4 SUBASE, Bangor Map Showing Extent of Site F Groundwater Contamination and
Regional Cross Section Location
5 Generalized Subsurface Cross Section A-A'
6 Shallow Aquifer Water Table Elevation Contour Map (April 1992)
7 Vertical Distribution of TNT in Soil
8 Extent of RDX and TNT in Shallow Aquifer, Former Wastewater Lagoon and Overflow
Ditch (North-south ProfIle)
9 Baseline Exposure Pathways, Hypothetical On-Site Conditions
10 Extent of Soil Above Cleanup Action Levels
11 Placement of Infiltration Barrier
ATTACHMENT A
RESPONSfVENESSS~Y
OVERVIEW
A-I
SUMMARY OF PUBLIC COMMENTS
A-1
RESPONSE TO COMMENTS
A-2"
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ACRONYMS AND ABBREVIATIONS
AKARM
ARARS
CERCLA
DNB
DNT
2,4-DNT
2,6-DNT
Ecology
EPA
FFA
GAC
HDPE
HEAST
HPLC
IAS
IRA
IRIS
MCL
mglkg
mglL
p.glL
MSL
MTCA
NA
NACIP
NB
NCP
NEPA
NFL
O&M
ppb
ppm
PQL
PVC
RAO
RCRA
RCW
RDX
RI/FS
ROD'
RME
All Known Available and Reasonable Methods
Applicable or Relevant and Appropriate Requirements
Comprehensive Environmental Response, Compensation, and Liability
Act of 1980
1,3- Dinitrobenzene
2,4- and 2,6-Dinitrotoluene
2,4- Dinitrotoluene
2,6- Dinitrotoluene
Washington State Department of Ecology
Environmental Protection Agency
Federal Facility Agreement
Granular Activated Carbon
High Density Polyethylene
Health Effects Assessment Summary Tables
High Perfonnance Liquid Chromatography
Initial Assessment Study
Interim Remedial Action
Integrated Risk Infonnation System
Maximum Contaminant Level
Milligram of chemical per kilogram of soil (dry weight)
Milligram of chemical per liter of water
Microgram of chemical per liter of water
Mean Sea Level
Model Toxics Control Act (Chapter 173-340 WAC)
Not Applicable
Naval Assessment and Control of Installation Pollutants
Nitrobenzene. .
National Oil and Hazardous Substances Pollution Contingency Plan
National Environmental Policy Act
National Priorities List
Operations and Maintenance
Parts per Billion (equivalent to ILg/L)
Parts per Million (equivalent to mg/kg or mg/L)
Practical Quantitation Limit
Polyvinyl Chloride
Remedial Action Objective
Resource Conservation and Recovery Act
Revised Code of Washington
Hexahydro-l,3 ,5-trinitro-l,3 ,5-triazine (Royal Demolition Explosive)
Remedial Investigation and Feasibility Study
Record of Decision
Reasonable Maximum Exposure
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SARA
SUBASE
SWFPAC
TBC
TCLP
TNB
TNT
USGS
UV/Ox
WAC
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Superfund Amendments and Reauthorization Act of 1986.
Naval Submarine Base
Strategic Weapons Facility Pacific
To Be Considered
Toxicity Characteristic Leaching Procedure
1,3,5- Trinitrobenzene
2,4,6- Trinitrotoluene
United States Geological Survey
Ultraviolet Oxidation
Washington Administrative Code
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RECORD OF DECISION
FINAL REMEDIAL ACTION
NAVAL SUBMARINE BASE, BANGOR, SITE F
DECISION SUMMARY
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1.0 INTRODUCTION
Under the Defense Environmental Restoration Program, it is the U.S.
Navy's policy to address contamination at Navy installations in a manner
consistent with the requirements of the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA), as amended by the
Superfund Amendments and Reauthorization Act (SARA). At the U.S.
Naval Submarine Base (SUBASE), Bangor, Site F (Operable Unit 2),
remedial action will be implemented to minimize potential health risks
associated with soil and groundwater contamination. The remedial action
will comply with federal and state applicable or relevant and appropriate
requirements (ARARs).
2.0 SITE NAME, LOCATION, AND DESCRIPI10N
U.S. Naval Submarine Base (SUBASE), Bangor is located in Kitsap
County, on Hood Canal approximately 10 miles north of Bremerton,
Washington. Site F is located in the south-central portion of SUBASE,
Bangor, approximately 1.5 miles east of Hood Canal (Figure 1). Land
surrounding SUBASE, Bangor is generally undeveloped or supports limited
residential use within the communities of Vinland (to the north), Olympic
View and Old Bangor (to the west), and Silverdale (to the south).
.
Site F (also known as Operable Unit 2) is a former ordnance wastewater
lagoon located immediately west of the former Segregation Facility in the
southcentral portion of SUBASE, Bangor. The former wastewater lagoon
is located in a clearing surrounded by forested area to the north, west, and
south. The site occurs in a generally closed basin, which receives surface
. water inflow from adjacent drainages, but no surface water drainage leaves
the area. The ground surface elevation near the disposal lagoon is
approximately 300 to 310 feet mean sea level (MSL) and increases to the
west until it reaches a plateau ranging in elevation from 375 to 400 feet
MSL. The former wastewater disposal site consisted of an approximately
300-square-foot unlined evaporation lagoon and overflow area located
adjacent to the Segregation Facility. Local features include a Naval
Heli-pad located approximately 700 feet northwest of Site F and barricaded
sidings and rail line approximately 1,500 feet west. The only access road
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into the site is via the Segregation Facility, and it is secured. Access to
Site F is restricted to authorized personnel.
3.0 SITE HISTORY AND ENFORCEMENT ACTIONS
.
The concern over the environmental impact of ordnance operations at
SUBASE, Bangor originated from activities prior to its commissioning as a
submarine base. From the early 1940s until 1971, the Bangor Naval
complex served as a munitions handling, storage, and processing site.
Limited demilitarization (demil) operations continued until about 1978.
Site F, which represents a former wastewater lagoon and overflow area,
was used between approximately 1960 and 1970 for the disposal of
wastewater produced during the demilitarization of ordnance items in the
adjacent Segregation Facility building. The Segregation Facility consisted
of three primary segregation plants and several other smaller buildings.
Figure 2 shows the historical features at the site including the location of
the former wastewater lagoon and overflow channel.
Between approximately 1957 and 1978, the segregation facility's primary
functions included the demil of Mk 6 and Mk 25 rocket warheads; Mk 6,
Mk 8, and Mk 9 mines and depth charges; and 5-inch projectiles, These
ordnance items contained primarily trinitrotoluene (TNT), Composition A,
Composition B, and Amatol. Residues of TNT, hexahydro-l,3,5-trinitro-
1,3,5-triazine (RDX), and picric acid were identified within the building
prior to its decontamination in 1980-81. Demiling activities reached a peak
during 1966 to 1970.
The procedures used for the demiling of ordnance items included
preliminary cutting or boring of large items using a mechanical tool,
followed by steam cleaning; other items were demiled entirely through a
steam melt-out process. During the steam-out process, steam was directed
into the ordnance, and the resulting condensate and solid explosive were
collected within a holding tank. Discharge from the holding tank was then
directed into skimming and settling chambers, which removed much of the
solid materials from the wastewater before final discharge.
Prior to 1972, the final wastewater solution was discharged through a drain
line directly into the former wastewater lagoon. Beginning in 1972-73,
wastewater was collected into 55-gallon barrels and delivered to the
SUBASE, Bangor liquid-waste incinerator.
~
The quantity of ordnance demiled within the Segregation Facility is not
well-documented. Reportedly, ordnance recovered within the Demil
Facility was flaked, boxed, and sent to magazines for future disposition.
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Some of these materials were apparently sold back to manufacturers. The
quantity of this "recycled" ordnance is not well-documented. Ordnance not
recycled was taken either to an ordnance burning area (Site A) located to
the north on SUBASE, Bangor or off base for thermal destruction.
\
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As stated above. during the period from 1960 to 1971, wastewater from
the Demil Facility was directed to an unlined inf11tration and evaporation
lagoon and overflow area. Periodically. the lagoon was allowed to dry out
by evaporation and/or drain to the overflow ditch south of the lagoon.
Waste materials present in surficial sediments of the lagoon were
reportedly "burned-off" in place with waste oil during the 1960s. or
transported to Site A (Operable Unit 1) for burning and disposal.
In February 1972. 500 cubic feet of soils were excavated from the top
several feet of the former lagoon area and delivered to Site A for burning.
To further reduce potential migration of contaminants from Site F soil into
the Shallow Aquifer. the former lagoon area was backfilled and covered
with asphalt in 1980.. .
Also in 1980. demil operations at the Bangor Segregation Facility were
transferred to the Indian Island Annex. The buildings were subsequently
decontaminated and converted to storage.
A considerable number of on-site investigations of the distribution and
transport of waste constituents at Site F have occurred since 1971. In
1978. the Navy A~sessment and Control of Installation Pollutants (NACIP)
program was initiated to evaluate waste disposal sites at SUBASE, Bangor.
including Site F. Work at Site F continued in 1981 as part of an Initial
Assessment Study (lAS) and in 1986 as part of a Characterization Study.
both under the Navy Assessment and Control of Installation Pollutants
(NACIP) program. In the latter year. Congress enacted the Superfund
Amendments and Reauthorization Act (SARA) which required federal
facilities to comply with the EPA's procedures at inactive waste sites. As
a result. the Navy suspended further NACIP program activities and phased
into the EPA Remedial Investigation/Feasibility Study (RI/FS) program.
On July 14. 1989. the EPA proposed SUBASE. Bangor. including Site F.
for listing on the National Priorities List (NPL). On August 30. 1990,
SUBASE, Bangor was officially listed on the NPL. The RI/FS
investigation at Site F was completed in November 1993. Prior to
completion of the RI/FS. a Record of Decision (ROD) for an interim
remedial action (IRA) was signed in August 1991 to limit further migration
of ordnance-contaminated groundwater from Site F. This ROD was
amended to provide for the use of granular activated carbon (GAC) for
groundwater treatment. and the change was documented in an Explanation
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of Significant Differences dated May 17, 1994. The IRA groundwater
containment system, currently under construction, is designed to
hydraulically limit the further migration of groundwater contaminants in
the Shallow Aquifer by groundwater extraction. The extracted
groundwater will be treated by GAC for ordnance and, as required, will
include treatment for nitrate to achieve all groundwater cleanup levels.
The treated water will be returned to the Shallow Aquifer through
reintroduction wells.
.
4.0 mGHLIGHTS OF COMMUNITY PARTICIPATION
The Community Relations Plan for Site F is presented in the RIfFS
Management Plan for the site, available for review in the information
repositories. Community relations activities have established
communication between the Navy and citizens living near SUBASE. The
actions taken to satisfy the requirements of the federal law have also
provided a forum for citizen involvement and input to the remedial action
decision.
The community relations activities at the site included the following:
~ Technical Review Committee (TRC) meetings with representatives from
surrounding communities;
~ Issuance of three fact sheets for the Site F RIfFS, which provided
updates on the work being performed and major findings;
~ Issuance of a fact sheet for the Site F Interim Remedial Action (IRA),
explaining the work being performed; and
~ Coordination with citizens groups formed in response to site
investigations of concern to the community.
The specific requirements for public participation pursuant to CERCLA
Sections 113(k)(2)(b) and 117(a) include releasing the Proposed Plan to the
public. This was done in January 1994. The Proposed Plan was placed in
the administrative record and information repositories.
The information repositories are located at Kitsap regional libraries:
Central Branch
1301 Sylvan Way
Bremerton, Washington
(206) 377-7601
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Bangor Branch (SUBASE access required)
Naval Submarine Base, Bangor
Silverdale, Washington 98315-5000
(206) 779-9724
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The Administrative Record is on file at:
Engineering Field Activity, Northwest
Naval Facilities Engineering Command
Olympic Place II
1040 NE Hostmark Street
Poulsbo, Washington
(206) 396-5984
Notice of the availability of the proposed plan, plus notice of a public
meeting on the proposed plan and public comment period was published in
the Bremerton Sun (January 23, 1994) and Trident Tides (January 28,
1994). The proposed plan was mailed to all interested people on January
21, 1994. A public comment period was held from January 23 to February
22, 1994. A public meeting was held on February 3, 1994, with
presentations given by the Navy, EPA, and Ecology. A total of 51 people
attended the public meeting.
Twenty-four comments (total) were received by the Navy concerning the
Proposed Plan. Most comments were submitted at the public meeting, and
one comment letter was submitted to the Navy outside of the public
meeting. The public comments are summarized and responses presented in
the Responsiveness Summary (Attachment A) portion of this document.
5.0 SCOPE AND ROLE OF OPERABLE UNITS
Two NPL sites exist at SUBASE, Bangor. The fIrst is Bangor Ordnance
Disposal Site A (Operable Unit 1), which was listed on the NPL on July
22, 1987. On August 30, 1990, the remainder of SUBASE, Bangor was
listed on the NPL, including an additional six operable units comprising 21
known or suspected hazardous waste sites. Site F, identifIed as Operable
Unit 2, is geographically separate from the other operable units at
SUBASE, Bangor. This Record of Decision addresses Operable Unit 2
only.
The selected Remedial Action at Site F will minimize potential future
health risks associated with soil and groundwater contamination at the site.
This action includes soil treatment to address risks posed by direct contact
exposures at the site and use of an infiltration barrier to restrict further
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releases of contaminants from soil to groundwater. The selected
groundwater action includes extracting contaminated groundwater from the
Shallow Aquifer at Site F, treating it to meet cleanup levels, and returning
it to the Shallow Aquifer through a series of wells. The groundwater
remedial action addresses principal and low-level risks posed by potential
future water supply use of site groundwaters, as well as future groundwater
discharge to surface water at seep locations.
. .
6.0 SUMMARY OF SITE CHARACTERISTICS
This section presents a summary of site conditions including a discussion of
the hydrogeologic characteristics and site waste constituents. The principal
exposure pathway of concern to human health and the environment is the
transport of site contaminants in the groundwater beneath the site.
Contaminated soils occur at the surface in the overflow ditch and in the
subsurface beneath the existing asphalt pavement covering the fonner
wastewater lagoon.
There are no critical habitat areas (including those of threatened or
endangered species), wetlands, floodplains, or historic preservation sites in
the area covered or affected by the selected remedial action.
6.1 Site Hydrogeologic Conditions
The three aquifer systems which exist beneath Site F are (from shallowest
to deepest) the Shallow Aquifer, the Sea level Aquifer, and Deeper
Undifferentiated Aquifer(s). Regional hydrogeologic studies indicate that
this sequence is regionally consistent. Groundwater contamination from
Site F is limited to the Shallow Aquifer, which is not used for water supply
at SUBASE, Bangor. The Sea Level Aquifer and deeper aquifers provide
the principal water supply for SUBASE, Bangor and surrounding
communities. No ordnance contaminants have been detected in the Sea
Level Aquifer or in deeper aquifers. The aquitard underlying the Shallow
Aquifer is both continuous across the Site F area and competent enough to
impede the downward migration of groundwater through it.
Figure 3 shows the location of monitoring wells located at Site F which
were used to assess hydrogeologic conditions beneath the site and provide
an effective monitoring network to assess groundwater quality. Additional
water supply wells at SUBASE, Bangor were also used to define
subsurface conditions beneath the Shallow Aquifer. The hydrogeologic
units beneath Site F are illustrated on Figure 5, which is oriented east to
west (cross section location line shown on Figure 4).
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The three hydrogeologic units that have significance for the Final Remedial
Action at Site F are:
.
. Vashon (Glacial) Till;
. Shallow Aquifer; and
. Vashon Proglacial Aquitard.
Subsurface explorations at Site F and other locations on SUBASE, Bangor
indicate that this vertical sequence of units is regionally consistent. Each
of the three significant hydrogeologic units is described below.
Vashon Till. The Vashon Till consists of a dense, unsorted gravelly, silty
sand. The till forms a low permeability veneer over the site which limits
the rate of infiltration to the underlying Shallow Aquifer. The thickness of
the till ranges from approximately 15 to 45 feet across the Site F area. In
the immediate area of the former wastewater lagoon, the till is
approximately 15 to 25 feet thick.
Lenses of silt and sand also occur within the till, but they are laterally and
vertically discontinuous. Although the isolated sand lenses become
seasonally saturated, they do not constitute a perched aquifer system
because of their lack of interconnection.
Shallow Aquifer. The Shallow Aquifer is an unconfmed (water table)
aquifer occurring within a thick sequence of Vashon Advance Outwash
sand, which directly underlies the Vashon Till. Depth to water in the
Shallow Aquifer ranges from approximately 50 feet near the former
wastewater lagoon to more than 150 feet in topographically higher areas to
the west. Locally, the aquifer is extensive, with a saturated thickness
ranging from 60 to 100 feet. .
The advance outwash deposits comprising the aquifer become fmer grained
with depth, grading from gravelly, coarse to medium sand downward into
very silty, fme sand. The lower very silty portion of the outwash is
differentiated from the rest of the outwash because of its unique
fme-grained nature. Field observations during drilling and confIrmatory
grain size analyses suggest that the very silty portion of the outwash sand
does not readily transmit water, and therefore effectively fonns the bottom
of the Shallow Aquifer. The Shallow Aquifer is exceptionally uniform
across the area and is relatively permeable, with an average horizontal
hydraulic conductivity estimated from pumping test and slug test data on
the order of 10-2 em! see.
The Shallow Aquifer water table slopes gently toward the northwest, with a
horizontal gradient of approximately 0.003 (3 foot drop for 1,000 feet
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horizontally). As shown on Figure 6, the groundwater flow direction
curves from a northwestern direction near the former lagoon to a more
north-northwesterly direction further downgradient. The average linear
groundwater flow rate is approximately 200 feet per year.
.
Vertical hydraulic gradients also exist within the Shallow Aquifer, which
appear to affect constituent migration within the aquifer. Downward
gradients occur near the former lagoon area, resulting in a downward
migration of waste constituents from the source area.
Available geologic and hydrologic information indicates that the Shallow
Aquifer discharges in the direction of flow (north-northwest) to on-base
seeps (Figure 5) which feed tributaries flowing to Hood Canal. There are
no on-base water supply wells completed in the Shallow Aquifer.
Although the available information indicates the Shallow Aquifer is not
continuous west of the SUBASE, boundary, shallow hand-dug wells in Old
Bangor and Olympic View west of the base boundary may be fed by seep
discharge from the Shallow Aquifer. The Shallow Aquifer seep discharge
is known to flow across the base boundary into small unnamed streams
which flow through Old Bangor and Olympic View toward Hood Canal.
Vashon Proglacial Aquitard. The Vashon Proglacial Aquitardis a thick -.
low permeability unit which separates the Shallow Aquifer from deeper
aquifer systems in the area (Figure 5). In the Site F area the aquitard is
approximately 60 to 80 feet thick and consists of clayey silt with occasional
interbedded silty sand and gravel layers. The laboratory-measured average
vertical hydraulic conductivity of the aquitard material is approximately
10-7 em/see, which is on the order of 100,000 times lower than horizontal
hydraulic conductivity of the overlying Shallow Aquifer.
6.2 Site Waste Constituents
6.2.1 Soils
Soil quality data were collected by the USGS in 1974 (99 samples), by
SUBASE, Bangor in 1981 (74 samples), and by Hart Crowser in 1990 and
1992 (125 samples). Soil samples were collected from ground surface to
the water table (depth of approximately 50 feet in 1990 through 1992).
The constituents analyzed in the soil samples prior to the Hart Crowser
sampling were largely limited to TNT and RDX. All of the soil samples
collected within the disposal area (other than the fill) contained detectable
concentrations of TNT and RDX. Conversely, only two soil samples
collected outside the lagoon and overflow ditch area exhibited detectable
ordnance concentrations. Furthermore, these two detections were from
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samples collected at the water table, suggesting that the presence of the
ordnance was likely due to groundwater transport.
..
The soil quality data confIrm that TNT is the primary ordnance constituent
present in soils in the disposal area, accounting for more than 90 percent of
the ordnance mass in soil. The other ordnance constituents detected at
lower concentrations in the disposal area soils include 1,3,S-trinitrobenzene
(TNB), 1,3-dinitrobenzene (DNB), and 2,4- and 2,6- dinitrotoluene (DNT).
Table 1 summarizes detected soil concentrations for the chemicals of
concern at Site F, which were determined during the RI/FS based on the
risk assessment.
The waste constituents disposed of at Site F infiltrated through the
unsaturated soils to the underlying water table (refer to Figure 7).
Termination-of discharge and capping of the disposal area in 1980 was
successful in restricting water infiltration below the lagoon and reducing
further leaching of contaminants from the soil. Comparison of soil quality
data collected by the USGS in 1974 and data collected during the RI/FS in
1990 suggests that minimal downward migration of contaminants occurred
following placement of the asphalt cap. .
The contaminated soil at Site F is not a regulated waste under th~ Resource
Conservation and Recovery Act (RCRA; also implemented pursuant to
Washington's Dangerous Waste Regulations -Chapter 173-303 WAC)
based on listing or characteristic. Contamination of the waste lagoon soil
at Site F did not involve a discarded chemical product nor a listed process.
In addition, Site F soils do not exceed designation criteria as a
characteristic waste using calculations based on the Toxicity Characteristic
Leaching Procedure (TCLP).
6.2.2 Groundwater
Groundwater quality data have been collected at Site F during prior studies
beginning in 1974, during development of the Current Situation Report in
1986/1987, and as part of the RI/FS in 1990 through 1992. Groundwater
samples have been collected from over 50 on-site wells completed in the
Shallow Aquifer. The database includes groundwater sampling data
collected by the USGS, by SUBASE, Bangor, and most recently by Han
Crowser.
The lateral and vertical distributions of site waste constituents within the
Shallow Aquifer are reasonably well-characterized. The ordnance waste
constituents detected have included TNT, RDX, DNT, TNB, and
nitrobenzene. Nitrate and low concentrations of various metals and organic
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chemicals were aiso detected. A summary of the chemicals of concern in
groundwater at Site F is presented in Table 1.
Based on the Table 1 summary, the ordnance constituents detected at the
highest concentrations in the Shallow Aquifer were RDX and TNT. RDX
is more mobile than TNT and the other ordnance constituents, and has
migrated the furthest downgradient from the Site F disposal area. Based
on existing data, the bulk of the TNT in the groundwater occurs within
approximately 1,000 feet of the former wastewater lagoon area. Nitrate,
like RDX, is highly mobile in the Shallow Aquifer. As a result, RDX and
nitrate defme the outer extent of groundwater contamination in the Shallow
Aquifer at Site F, which extend approximately 3,000 feet northwest of the
former wastewater disposal lagoon (Figure 8).
..
As discussed above, groundwater in the Shallow Aquifer flows at a rate of
approximately 200 feet/year toward the north-northwest, and discharges as
seeps located within the western base boundary. RDX is the most mobile
ordnance compound in groundwater at Site F. Based on the observed
distribution of RDX in the Shallow Aquifer, RDX appears to be migrating
at rate of approximately 100 feet/year. No ordnance compounds have
been detected in the seeps. Based on the estimated rate of RDX migration
. in the aquifer and the distance to the seeps in the direction of groundwater
flow, it should take 30 or more years for RDX to reach the seeps, if no
remedial response action is taken.
To evaluate the possibility of existing impacts to water supply wells within
downgradient communities from Site F, SUBASE, Bangor (in conjunction
with the Kitsap County Health District) conducted an annual monitoring
program of selected off-site water supply wells from 1984 to 1987. The
sampling sites included twelve (12) off-base domestic supplies east and
west of Site F, which obtained water from both the Shallow and Sea Level.
Aquifers. Eight SUBASE, Bangor water supply wells completed within the
Sea Level Aquifer or deeper aquifers have also been monitored. Samples
collected during the RIfFS field investigation in 1990 from on-base and
off-base water supply wells completed in the Sea Level Aquifer and Deeper
Aquifers as part of the RIfFS confirmed no ordnance contamination
associated with Site F. Samples collected during the RIfFS included the
on-base SWFPAC well (used for reserve water supply), which is located
downgradient of Site F and is screened solely in the Sea Level Aquifer
(Figure 5). In addition, no ordnance compounds were detected in a 1991
sample collected by the State Department of Health from Old Bangor No.
19, located in the community of Old Bangor northwest of Site F.
The contaminated groundwater at Site F is not a regulated waste under
RCRA based on listing or characteristic. The contaminated groundwater
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did not originate as a discarded chemical product (U- and P-listed; WAC
173-303-081) nor did it come from a listed source (F- and K-listed; WAC
173-303-082). Groundwater would not be considered a federal hazardous
waste or a state dangerous waste until it is removed (extracted) from the
aquifer. Although exceedence of the TCLP threshold concentration for
2,4-DNT was observed in point samples from wells located adjacent to the
former waste water lagoon, ordnance concentrations observed during
groundwater extraction were below the 2,4-DNT threshold.
7.0 SUMMARY OF SITE RISKS
All chemicals detected at Site F were screened following EP A's 1989 Risk
Assessment Guidance for Superfund to identify those chemicals which in
combination contribute 99 percent or more of the cumulative site risk.
Selection of such indicator chemicals was based on consideration of the
concentrations encountered, environmental mobility, and toxicity.
Chemicals eliminated in the screening process included several metals
(e.g., arsenic), and some ordnance degradation products (e.g.,
2,6-diamino-4-nitrotoluene). The eliminated chemicals were either present
at concentrations typical of natural background conditions or were below
conservative risk-based criteria. Some of the eliminated chemicals lacked
quantitative toxicity information necessary to assess human health or
environmental risks.
A quantitative human health risk assessment and ecological evaluation was
performed for Site F to assess baseline risks at the site under a
no-future-action scenario. Only those exposure pathways likely to be
important to the overall human health risk assessment were retained for
quantitative evaluation, as summarized in Table 2. Reasonable maximum
human exposures were estimated for the following pathways:
~ Direct skin contact with soil;
~ Incidental ingestion of soil, inhalation of air;
~ Drinking water consumption of groundwater;
~ Direct skin contact with groundwater; and
~ Consumption of freshwater aquatic life (future conditions in the seep
area) .
7.1 Human Health Risks
Based on the above evaluation, chemicals at Site F with the potential to
pose a risk to human health were identified. The chemicals of concern
identified from this evaluation, listed in decreasing order of calculated risk,
are as follows:
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. 2,4,6- Trinitrotoluene (TNT);
. 2,4- and 2,6-Dinitrotoluene (DNT);
. Hexahydro-l,3 ,S-trinitro-l,3 ,S-triazine (RDX);
. 1,3 ,S- Trinitrobenzene;
. 1,3-Dinitrobenzene;
. Nitrate;
. Nitrite; and
. Manganese.
Other chemicals detected at Site F were below the most conservative risk
targets (Hazard Quotient less than 1 and lifetime cancer risk less than 1 in
1,000,000).
A cancer risk level of 1 in 10,000 means that one additional person out of
ten thousand is at risk of developing cancer due solely to site conditions if
the site is not cleaned up. A hazard quotient (ratio of the level of exposure
to an acceptable level) greater than 1.0 indicates that the exposure level
exceeds the protecu,ve level for that panicular chemical. If the hazard
quotients for individual chemicals are less than 1.0 but the sum of all
chemicals' hazard quotients for an exposure medium (called the hazard
index) is greater than 1.0, then there may also be a concern for potential
health effects.
Although the existing access and use of Site F is restricted, potential
human health risks were evaluated based on the conservative assumption of
unrestricted residential use of the site. The risk assessment was also based
on a second conservative assumption that a hypothetical residential
dwelling would obtain its water supply from the most contaminated portion
of the Shallow Aquifer, located next to the former wastewater lagoon.
These conservative exposure assumptions allowed site hazards to be
evaluated under a Reasonable Maximum Exposure (RME) scenario,
consistent with state and federal hazardous site cleanup regulatioQS.
Potential exposure pathways are depicted on'Figure 9. Tables.3 through 9
provide exposure assumptions used to calculate intake for all pathways.
Tables 10 and 11 provide reference doses and slope factors, respectively,
for all chemicals of potential concern which were screened in the risk
assessment.
For carcinogens, the baseline risk is presented as the possible
(upper-bound) risk of contracting some fonn of cancer given lifetime (30-
year) exposure to a chemical. Federal guidelines for acceptable
upper-bound cancer risk range from a chance of 10'4 (1 in 10,000) to 10-6
(1 in 1,000,000) of developing cancer due to exposure to a carcinogen.
The comparable cancer risk range recognized by the Washington State
Model Toxics Control Act (Chapter 173-340 WAC) is 10-5 to 10-6.
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.
Non-carcinogenic risk is evaluated by dividing the daily dose resulting
from site exposure by the EP A estimate of acceptable intake (or reference
dose) for chronic exposure. If the ratio between these values (termed the
Hazard Quotient) is less than 1, then non-carcinogenic risks are not
indicated. Conversely, Hazard Quotient values greater than 1 indicate a
potential risk to human health.
The calculated Hazard Index and lifetime cancer risk associated with
individual chemicals and pathways at Site F are presented in Tables 12 and
13, respectively. A total Hazard Index of 840 and total cumulative RME
lifetime cancer risk of 1 x 10-2 were calculated based on a summation of all
chemicals and potential pathways at Site F.
Chemicals with a cumulative pathway RME Hazard Index exceeding 1 are
(in descending order): TNT (620); TNB (180); DNB (18); RDX (9); DNT
(8); nitrate (2); nitrite (2); and manganese (2). Chemicals with a
cumulative pathway RME lifetime cancer risk exceeding 10-6 are (in
descending order): DNT (5 x 10-3); TNT (4 x 10-3); and RDX (1 x 10-3).
All other chemicals were below general risk targets (Hazard Index less
than 1 and lifetime cancer risk below 10-6).
The pathway-specific RME Hazard Index was highest for combined
groundwater exposures (740; drinking water ingestion and water contact),
intermediate for combined soil exposures (98; soil contact and incidental
ingestion), and lowest for potential future fish consumption (0.7; seep
source) and dust inhalation (less than 0.1). A similar relative ranking
occurred with RME lifetime cancer risks, with groundwater pathways at
9 x 10.3, spil pathways at 6 x 10-4, fish consumption at 1 x 10.5, and dust
inhalation at 5 x 10.'.
Table 14 provides a summary of the assumptions and uncertainties in the
risk assessment. As indicated in this table, most of the assumptions
inherent in the risk assessment tend to overestimate site risk, thus
providing a conservative evaluation of potential risks associated with Site
F. .
7.2 Ecological Risk Evaluation
An ecological risk assessment was performed to determine whether the
chemicals associated with Site F have the potential to affect local animal
populations and ecological communities, particularly valuable ecological
resources (e. g., endangered species or wetlands). The assessment
addressed both aquatic and terrestrial exposures.
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There are no critical habitats or endangered species or habitats of
endangered species affected by site contamination. However, future
impacts to sensitive aquatic species may possibly occur in the surface water
seep area when groundwater chemicals begin arriving in this area. The
predicted upper-bound concentration (RME) of TNT in the seep discharge
is 76 p.g/L (predicted arrival time of approximately 30 years), which
exceeds an estimated criterion to protect aquatic life (40 p.g/L). The RME
condition estimate is based on a hypothetical combination of "worst-case"
assumptions to defme the physical and chemical transport parameters which
affect constituent transport in groundwater (Le., predict maximum
concentrations in the minimum time period). In addition, the predicted
RME concentration of TNT does not consider potential exposure to natural
sunlight (photolysis). Photolysis has been shown to rapidly degrade TNT
in natural waters. Consequently, actual concentrations are likely to be
lower than the RME case. The predicted upper-bound concentrations of all
other chemicals were either within the range observed in upgradient
monitoring wells (background groundwater quality), or below available
aquatic life criteria.
~
Similarly, calculated risk to terrestrial wildlife were also generally below
risk criteria. Soil cleanup actions which address human health will also be
protective of terrestrial wildlife.
7.3 Need for Remedial Action
The results of the baseline risk assessment indicate that the cumulative
cancer risk calculated for Site F exceeds the EP A upper-bound guideline of
10-4 (1 in 10,000) assuming most-conservative conditions. Furthermore,
potential non-cancer risks exceed human health criteria. The potential for
future ecological impacts to sensitive aquatic species were predicted at the
seep discharge area if the groundwater contamination arrives there
unabated.
Based on these risk assessment results, soil and groundwater contamination
at Site F exceeds established health-based thresholds. Consistent with the
National Contingency Plan and EP A policy, remedial action is warranted to
address these potential risks to human health and the environment.
8.0 CLEANUP STANDARDS
Cleanup objectives (remedial action objectives [RAOs]) for Site F were
developed for the affected media and individual chemicals of concern,
based on a review of regulatory standards and criteria, and results of the
human health and ecological risk assessments. Two primary cleanup action
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8.1 Soil
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objectives were identified based on site conditions and the principal site
risks, specifically: (1) eliminate the risk associated with potential direct
contact with contaminated soils at Site F; and (2) cleanup groundwater
contamination in the Shallow Aquifer at Site F to achieve the most cost-
effective reduction in overall site risk. In addition, chemical-specific
RAOs specify the constituents and media of concern, potential exposure
pathways, and preliminary remediation goals.
A range of RAOs were developed for soil, groundwater, and surface
water, including cleanup goals based on CERCLA threshold risk targets
defmed relative to a cumulative upper-bound Hazard Index of 1 and a
lifetime upper-bound cancer risk of 1 in 10,000. Applicable or relevant
and appropriate requirements (ARARs), including drinking water
Maximum Contaminant Levels (MCLs), surface water quality standards,
and State of Washington Model Toxics Control Act (MTCA) Cleanup
. Standards were also considered in the development of RAOs. The MTCA
Method B cleanup standards provide ARARs for most of the chemicals and
pathways of concern at Site F. The media-specific RAOs are listed in
Table 15 and are discussed below.
The primary chemicals of concern in soil are TNT, RDX, and DNT.
Different RAOs for soil were developed to assess two potential exposure
pathways: direct soil contact (residential site use scenario) and protection
of groundwater use. The soil RAOs based on direct residential soil
contact, which apply to a maximum depth of 15 feet (per MTCA), are:
TNT (33 mg/kg); RDX (9.1 mg/kg); DNT (1.5 mg/kg); TNB (1.1 mg/kg);
and DNB (2.1 mg/kg). The soil RAOs based on protection of groundwater
(per MTCA) were determined based on site-specific soil:water partition
coefficients and conservative assumptions of site conditions. These
groundwater protection RAOs are considerably more stringent: TNT (0.3
mg/kg); RDX (1 mg/kg, based on the current Practical Quantitation Limit
[PQL] for Method 8330 HPLC analysis); and DNT (0.5 mg/kg, also based
on the PQL). Calculations of the site-specific soil RAOs based on
groundwater protection (and corresponding PQLs) are provided in a
technical memorandum included in the Administrative Record (technical
memorandum included as Attachment A to Responses to EP A Comments
on Draft Proposed Plan for Site F, dated December 22, 1993).
An estimated 140,000 cubic yards of soil in the former wastewater lagoon
and overflow ditch area exceed the most restrictive soil RAOs (i.e., those
based on groundwater protection). By comparison, only about 1,000 cubic
yards of soil in these areas exceed direct residential soil contact RAOs.
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8.2 Groundwater
Based on the risk assessment, TNT, TNB, DNB, RDX, and DNT are the
primary chemicals of concern in the Shallow Aquifer. Nitrate is also a
chemical of concern in the Shallow Aquifer; however, it poses far less risk
than the ordnance constituents, accounting for less than 1 percent of the
non-cancer risk. As discussed above, the extent of RDX and nitrate within
the Shallow Aquifer defmes the outer boundary of groundwater
contamination from all constituents identified at the Site F. The
groundwater RAOs are: RDX (0.8 ,.,.g/L); TNT (2.9 ,.,.g/L); DNT (0.13
,.,.g/L); TNB (0.8 ,.,.g/L); DNB (1.6 ,.,.g/L); nitrate (10,000 ,.,.g/L); nitrite
(490 ,.,.g/L); and manganese (50 ,.,.g/L).
~
8.3 Surface Water
No impacts to surface water have occurred at the site. Based on protection
of human health and the environment, the surface water RAOs for
protection of aquatic life are: RDX (260 ,.,.g/L); TNT (40 ,.,.g/L); DNT
(300 ,.,.g/L); TNB (80 ,.,.g/L); DNB (100 ,.,.g/L);.nitrate (10,000 ,.,.g/L); and
manganese (1,500 ,.,.g/L). There is no aquatic life surface water RAO for
nitrite. Although surface water originating at the seeps is not a current
drinking water source, surface water RAOs for drinkiiJ.g water exposure
are: RDX (0.8 ,.,.g/L); TNT (2.9 ,.,.g/L); DNT (0.13 ,.,.g/L); TNB (0.8
,.,.g/L); DNB (1.6 ,.,.g/L); nitrate (10,000 ,.,.g/L); nitrite (490 ,.,.g/L); and
manganese (50 ,.,.g/L).
9.0 DESCRIPTION AND COMPARISON OF ALTERNATIVES
9.1 Soil Remediation Alternatives
A wide range of potential soil remediation alternatives were initially
identified for screening in the Feasibility Study (FS) and, of these, seven
were selected for detailed analysis in the FS. During development of the
Proposed Plan for Final Cleanup of Site F, the soil remediation alternatives
were refmed, including combination and addition of technologies. The five
soil alternatives carried forward in the Proposed Plan are:
No Action;
(1)
(2)
Limited Action (access restrictions to the site);
(3)
Capping of Soils Exceeding Direct Contact and Groundwater
Protection Soil Cleanup Levels;
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(4)
Excavate Contaminated Soils to a Depth of 15 Feet with
Concentrations above MTCA Method B Residential Contact
Cleanup Levels (1,000 cubic yards), On-Site Biological Soil
Treatment, and Placement of an Infiltration Barrier over Remaining
Soils Posing a Risk to Groundwater; and
(5)
Removal of All Soils Exceeding Most Restrictive Soil RAOs
(140,000 cubic yards) and On-Site Incineration.
Discussions of the five soil alternatives are presented below.
No Action
The No Action alternative provides a baseline to compare the other
alternatives against to evaluate their effectiveness. The No Action response
would entail leaving the site as it currently exists.
Limited Action
Under the Limited Action alternative, existing site controls would be
expanded to pennanently restrict access to contaminated soils at the site
(e.g., fences, etc.). In addition, the Navy would put into effect a
pennanent order preventing future use of the site.
Soil Capping
The Soil Capping alternative would involve installation of a surface cap
over all the contaminated soils at Site F (areal extent estimated at roughly 2
acres). The cap would consist of a synthetic membrane such.as PVC or
HDPE, which would be sloped for drainage and covered with soil and
vegetation for protection. Additional components such as geotextiles
and/or sand might also be employed for cushioning and drainage.
In addition to controlling surface water infiltration, the surface cap would
provide isolation of the contaminated soil from the atmosphere and from
direct contact with humans and animals. The cap would be maintained and
repaired as necessary. Because the soil cap would be used to prevent
direct contact with contaminated soils, access restrictions would be
required to reduce the risk of damaging the cap.
Excavation and On-Site Biological Treatment of "Direct Contact" Soils
and Placement of Infiltration Barrier
This alternative involves excavation of all soils to a depth of 15 feet with
concentrations above direct contact cleanup levels (e.g., TNT
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concentrations above 33 mgfkg). MTCA defmes a depth of 15 feet as the
reasonable maximum depth of direct contact exposure during hypothetical
site development. The approximate IS-foot excavation depth is shown on
Figure 7. Following excavation, these soils would be mixed with organic
amendment (e.g., potato waste, cow manure, sawdust) and subjected to
controlled conditions which would facilitate growth of naturally occurring
microorganisms in the mixture. The microorganisms would use the
contaminant compounds as a food source, transforming the contaminants
into less-toxic compounds. .
..
An estimated 1,000 cubic yards of soil will be excavated in this alternative
(based on the RIfFS characterization fmdings). This soil volume would
include soils with lower concentrations (below direct contact cleanup
levels) which will need to be excavated to reach higher concentration soils
below. All excavated soils will be treated together. Verification sampling
will be conducted to a depth of 15 feet after excavation. Any remaining
soils with concentrations above direct contact cleanup levels, will also be
excavated. .
Biological treatment would remove chemicals of concern and their
degradation products to residual concentrations that are below direct
contact RAOs. Recent results of treatability studies performed on a sample
of Site F soil indicate that biological treatment is an effective treatment
technology for these soils. Because biological treatment has been selected
as the preferred alternative for treatment of contaminated soils at Site D
(Operable Unit 6), the soils from the two SUBASE, Bangor sites may be
treated together.
Excavated glacial till soils present at Site F may require pretreatment by
sieving and screening to remove rocks and to break apart the soil. The
pre-treated soil would then be mixed with organic amendment, and layered
with gravel in biological treatment piles. Soil pile moisture, temperature,
oxygen, and nutrient content would be monitored and adjusted as required.
Tilling of the soil would be required to supply oxygen and maintain
optimum temperature. The biological treatment piles would be sheltered
from the rain and provided with adequate ventilation. Run-on would be
controlled to eliminate leachate generation and runoff.
Because the biologically treated soils would likely not be in compliance
with soil cleanup levels protective of groundwater, the treated soils would
be placed back in the excavation prior to installation of the infiltration
barrier over those areas. The increased volume of soil which results from
biological treatment may be used to fill the overflow ditch to grade prior to
placement of the infiltration barrier.
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Current treatability study results (based on laboratory testing) indicate that
biological treatment can successfully reduce soil concentrations to below all
direct contact soil cleanup levels. If pilot testing indicates that biological
treatment would not be appropriate for treating ordnance compounds in Site
F soils, alternative treatment technologies (e.g., incineration), will be
evaluated as a contingency.
The infiltration barrier would consist of a low-permeability material (e. g. ,
asphalt, clay, or geomembrane) used to cover residual soils containing
ordnance concentrations that may pose a risk to groundwater quality in the
Shallow Aquifer (Figure 11). Soils posing a potential risk to groundwater
at Site F cover an area of approximately two acres and extend to the
Shallow Aquifer water table (roughly 50-foot depth) over much of that area
(Figure 7).
As stated in Section 8.1 above, soil cleanup levels for protection of
groundwater default to Practical Quantitation Limits (PQLs) for some
ordnance compounds. However, because the groundwater protection soil
cleanup levels for Site F were estimated using conservative assumptions,
and the volume of soil at Site F with concentrations below PQLs is small,
soils with ordnance concentrations at or below PQLs should not pose a risk
to groundwater. Furthermore, the infiltration barrier will extend beyond
the zone of contaminated soils, thus providing an additional factor of
safety.
Like the soil cap discussed in the previous alternative, the infiltration
barrier would restrict infiltration of rainwater through contaminated soils,
and thus limit migration of contaminants from soil to groundwater.
However, unlike the soil cap, the infiltration barrier does not have to
provide protection against direct contact with contaminated soils at the site
since these soils have been permanently treated to concentrations below
direct contact action levels. Therefore, this .alternative would not require
access restrictions once the soil treatment is completed and the infiltration
barrier is in place. As part of remedial design, an operations and
maintenance (O&M) plan will be developed for the infiltration barrier to
ensure its long-term integrity.
Excavation of All Contaminated Soils and On-Site Incineration
This alternative involves excavation of all contaminated soils (relative to
soil cleanup levels for groundwater protection; see Figures 7 and 10) and
on-site incineration using a mobile incinerator. Incineration involves the
volatilization and combustion of organic contaminants at high temperature
(1,600 to 2,000 degrees F). Soil is mixed with a fuel source and
combusted in an enclosed, oxidizing environment. Contaminants are
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converted to inert ash and gases. These gases are further treated to ensure
that emissions to the atmosphere meet all air quality criteria.
Although the specific incinerator type would be detennined during final
design, three incinerator designs in common use are rotary kiln, infrared,
and fluidized-bed. Of these, only the rotary kiln incinerator has been
demonstrated on ordnance-contaminated soils. The technical and
administrative implementability of on-site incineration has been
demonstrated at other military installations.
.
Following incineration, the sterile soil would be used to backfill the
excavated area to grade.
9.2 Groundwater Remediation Alternatives
The Site F Feasibility Study included the initial screening of a wide range
of groundwater remediation alternatives and detailed evaluation of eight of
these. Based on the comparative analysis of alternatives in the Feasibility
Study, a more refmed list of alternatives was developed for evaluation in
Site F Proposed Plan. .
The three alternatives evaluated for fmal groundwater remediation at Site F
include:
(1)
No Action;
Limited Action (institutional controls restricting groundwater use);
(2)
(3)
Enhanced Groundwater Extraction, Treatment by Granular
Activated Carbon (GAC), and Reintroduction to the Shallow
Aquifer.
Discussions of the three groundwater alternatives are presented below.
No Action
The No Action alternative assumes that the Site F IRA is not implemented,
long-term groundwater and seep monitoring are not conducted, and no
other remedial activities are completed. Under this alternative, migration
of ordnance contamination in the Shallow Aquifer would continue.
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Limited Action
The Limited Action alternative would consist of deed restrictions
prohibiting the installation of water supply wells into the contaminated
portion of the Shallow Aquifer. A program of periodic groundwater and
surface water sampling and analysis would be instituted to monitor
ordnance concentrations in the Shallow Aquifer and at the seeps. If
necessary in the future, restrictions on use of the surface water streams fed
by the seeps (Shallow Aquifer discharge) may also be required.
Enhanced Groundwater Extraction, Treatment by GAC, and
Reintroduction to the Shallow Aquifer
Groundwater would be extracted at a rate to optimize removal of
contaminants from the Shallow Aquifer, treated on site using the Granular
Activated Carbon (GAC) treatment technology, and returned to the Shallow
Aquifer through reintroduction wells. Treatment by GAC is a
well-established technology that has been demonstrated to treat Site F
groundwater to meet all groundwater cleanup standards. Used carbon
would be transported to the carbon supplier's facility for thermal
regeneration (reactivation). The regeneration process would provide
permanent destruction of adsorbed ordnance compounds. No on-site air
emissions would occur under this alternative.
In the Feasibility Study, five different groundwater extraction, treatment,
and reintroduction alternatives were evaluated. The five alternatives
differed in terms of the groundwater extraction rate and the time period of
operation. Two groundwater treatment options, GAC and UV lOx, were
included in each of the five alternatives since they were determined to be
the most appropriate for application at the site. However, because GAC
provides the same treatment efficiency as UV lOx at a much lower cost,
and because GAC has been chosen for use in the Site F IRA, only GAC
was carried forward for evaluation of a final groundwater treatment
alternative for Site F.
Groundwater Extraction. Groundwater remedial alternatives were
evaluated based on results of numerical contaminant transport modeling
during design of the Site F Interim Remedial Action (IRA), and as part of
the Feasibility Study. The number and locations of new extraction wells
(in addition to those extraction wells installed for the Site F IRA), and their
respective pumping rates, will be evaluated by conducting additional
groundwater modeling during design of the final groundwater remediation
system.
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Groundwater modeling evaluations were conducted in an effort to predict
the effectiveness of groundwater extraction in removing contaminants from
the Shallow Aquifer. The general fmdings of the groundwater modeling
results included:
(1)
(2)
(3)
(4)
The existing Interim Remedial Action (IRA) groundwater
extraction, treatment, and reintroduction system (225 gpm target
pumping rate) currently being implemented by the Navy to limit
further migration of contamination in the Shallow Aquifer at Site F
is not sufficient to achieve the groundwater RAOs (drinking water
standards) in a reasonable time period.
A groundwater extraction system pumping rate of 425 gpm or
greater (enhanced system) will likely be required to optimize
contaminant removal from the Shallow Aquifer.
Based on conservative contaminant transport assumptions,
substantial reduction in ordnance contamination concentrations in
the Shallow Aquifer by groundwater extraction is feasible,
especially during the early period of system operation when
dissolved constituent concentrations within the Aquifer will be high.
Based on the modeling results, achieving the RAOs for all
chemicals of concern is considered feasible. However, it is difficult
at this point to predict with certainty how well the groundwater
extraction system performance will compare to the model results.
The four principal contaminants of concern-RDX, TNT, DNT,
and nitrate-vary in terms of their mobility based on soil:water
partitioning. Consequently, removal of these chemicals from the
Shallow Aquifer is also indicated to vary. Nonetheless, even
considering these uncertainties, groundwater extraction is considered
the best means of permanently addressing the groundwater
contamination at Site F. Actual contaminant removal performance
data collected during implementation of the Site F IRA will greatly
improve the ability to predict the degree of aquifer restoration
achievable by groundwater extraction and treatment.
Results of the groundwater modeling indicate that, at an extraction
rate of approximately 425 gpm, the RDX cleanup level would be
achieved in approximately 6 to 10 years (and nitrate even more
rapidly), whereas TNT and DNT remediation may require an
additional 5 to 20 years of groundwater treatment.
(5)
Groundwater in the immediate vicinity of the former wastewater
lagoon contains the highest concentrations of the least mobile
ordnance constituents, TNT and DNT, and therefore will require
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the longest time period of groundwater extraction system operation
to achieve cleanup levels. It is anticipated that the initial
groundwater extraction system will be designed to focus on removal
of the more mobile constituents, RDX and nitrate, and thereby
greatly reduce the overall zone of groundwater contamination. The
groundwater extraction system will likely require enhancements
(e.g., distribution of pumping rates) as the zone of contamination is
reduced to the less mobile (slower desorption) constituents, TNT
and DNT. Such modifications may include increased pumping or
pulse pumping in the vicinity of the former lagoon to optimize
removal of TNT and DNT. System modifications (e.g., pulse
pumping) may also be used as appropriate to enhance removal of
RDX andlor nitrate.
Startup and operation of the IRA groundwater extraction system will
provide valuable information on actual ordnance constituent removal rates
over time which will allow improved prediction of system performance.
This information will be useful in optimizing the final design of the
groundwater extraction system.
Groundwater Treatment. Extracted groundwater will be treated using
GAC, and ion exchange as necessary to remove nitrate; to meet all ARARs
(drinking water standards) prior to reintroduction back to the Shallow
Aquifer.
Groundwater Reintroduction. Consistent with the Record of Decision for
the Site F IRA, treated groundwater will be reintroduced back into the
Shallow Aquifer. This disposal option facilitates on-base disposal of the
treated groundwater and minimizes concern for depletion of the
groundwater resource. This groundwater recharge can potentially be
designed to assist in preventing groundwater contamination migration and
accelerate contaminant removal. Based on evaluations conducted during
design of the Site F IRA, reintroduction will be conducted through a series
of reintroduction wells completed in the Shallow Aquifer. Six
reintroduction wells have been completed as part of the Site F IRA.
10.0 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
Each of the soil and groundwater remediation alternatives discussed above
were evaluated against the nine criteria specified by the NCP. The No
Action Alternative was included as a baseline comparison. The nine
criteria include two threshold criteria which must be met for an alternative.
to be selected, five balancing criteria for comparing and choosing a
preferred alternative, and two modifying criteria (State acceptance and
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community acceptance) which are factored into selection of the final
cleanup action. The following is a comparison of the soil and groundwater
alternatives based on the NCP evaluation criteria.
10.1 Evaluation 0/ Soil Remediation Alternatives by Criteria
Overall Protection of Human Health and the Environment. Two of the
four soil alternatives, Treatment of "Direct Contact" Soils with Placement
of Inflltration Barrier, and Treatment of All Contaminated Soils are
protective of human health and the environment. Both of these alternatives
eliminate risk due to direct contact with contaminated soils using
permanent treatment. Both alternatives also limit further migration of
contaminants from soils to the Shallow Aquifer, and thus are protective of
the Shallow Aquifer.
The Soil Capping alternative limits potential exposure to contaminated soils
at Site F, and limits migration of contaminants into the Shallow Aquifer.
However, because no permanent treatment is conducted in this alternative,
it is considered to be less protective than either of the soil treatment
alternatives. Limited Action prevents exposure to contaminated soils
through institutional controls, but provides no protection to the Shallow
Aquifer from contaminated soils and provides no permanent treatment. No
Action is not protective of human health or the environment, and thus will
not be considered further in this evaluation.
Compliance with ,ARARs. Both soil alternatives with a soil treatment
component, the Treatment of "Direct Contact" Soils and Placement of
Infiltration Barrier, and Treatment of All Contaminated Soils alternatives,
also achieve ARARs. The Limited Action alternative does not achieve
ARARs since MTCA does not recognize institutional controls as a
substitute for technically feasible cleanup actions. The Soil Capping
alternative (containment) complies with the MTCA ARARs only if
permanent treatment is demonstrated to be impracticable. Since Ecology
has determined that soil treatment is practicable, Soil Capping does not by
itself achieve all ARARs.
Soils at Site F do not designate as characteristic dangerous or hazardous
wastes and are not listed hazardous wastes. Therefore, handling,
treatment, and disposal requirements for dangerous and hazardous wastes
are not ARARs for soil remediation at Site F.
Long-Term Effectiveness and Permanence. Both soil treatment
alternatives, Treatment of "Direct Contact" Soils and Placement of
Infiltration Barrier, and Treatment of All Contaminated Soils, permanently
eliminate the risk due to direct contact with contaminated soils at Site F.
"
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..
Both of these alternatives also provide long-term protection of the Shallow
Aquifer, but by different means. Treatment of "Direct Contact" Soils
includes the placement of an infiltration barrier which will restrict
infiltration, and thus limit leaching of contaminants into the Shallow
Aquifer from residual contaminated soils. Treatment of All Contaminated
Soils removes and permanently treats all soils posing a potential risk to
groundwater quality. The Soil Capping alternative would prevent direct
contact with contaminated soils and would reduce migration of
. contaminants from soil to the Shallow Aquifer, but provides no permanent
treatment. The Soil Cap could be effective in the long-term with proper
maintenance and site access restrictions to ensure its integrity. The
long-term effectiveness of the Limited Action alternative in preventing
direct contact with contaminated soils is dependent on compliance with the
access and land-use restrictions.
Reduction of Toxicity, Mobility, or Volume Through Treatment. The
Treatment of "Direct Contact" Soils and Placement of Infiltration Barrier
alternative, and Treatment of All Contaminated Soils alternative include a
reduction in toxicity and contaminant volume through treatment. In
addition, placement of the Infiltration Barrier greatly reduces mobility of
contaminants in the unsaturated zone. Treatment of All Contaminated Soils
involves removing all soil contaminants, thus providing complete reduction
of toxicity, mobility, and volume through treatment. The Soil Capping
alternative reduces the mobility of soil contaminants by restricting
infiltration of rainwater through contaminated soils, but does not reduce
either the toxicity or volume of contaminated soils through treatment.
Limited Action provides no reduction in toxicity, mobility, or volume of
soil contaminants.
Short-Term Effectiveness. The Limited Action alternative is very
effective at reducing risk to human health and the environment in the short
term. The Soil Capping alternative would provide protection from contact
with contaminated soil within about two to four months. The Treatment of
"Direct Contact" Soils and Placement of Infiltration Barrier alternative
would require roughly six months from time of treatment startup to achieve
protection. Because of the much larger soil volume to be excavated and
treated, the Treatment of All Soils alternative would require roughly two
years from startUp to achieve protection, and is thus less effective in the
short term. Access restrictions currently in place at SUBASE, Bangor
would afford short-term effectiveness to all the soil alternatives to
non-construction worker exposure. Dust control would be implemented
during excavation in both of the soil treatment alternatives to limit
exposure to workers or off-site persons.
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Implementability. Limited Action is the most implementable alternative
since fences or other measures could be constructed quickly around the
area of soil contamination, and land-use restrictions could be implemented
quickly. The Soil Capping alternative is highly implementable since it uses
established techniques and materials, including locally available soils.
Treatment of "Direct Contact" Soils and Placement of Infiltration Barrier is
considered to be relatively implementable. Biological soil treatment may
require relatively large volumes of organic amendment (potato waste, cow
manure, sawdust, etc.) be added to the soil, to provide amendment:soil
volume ratios as high as 70:30. Placement of the Infiltration Barrier
(which may be as simple as asphalt pavement covered with fill) would be
highly implementable.
Because of the large quantity of soils associated with the Treatment of All
Contaminated Soils alternative (200,000 tons) and the necessity of using
deep-pit excavation techniques, this alternative is considered less
implementable than the others. Furthermore, there are technical and
administrative concerns associated with incinerating this very large quantity
of soil. .
Cost. The cost of each soil remediation alternative, in order of increasing
present worth, is shown below:
Soil Capping
Annual Present
Capital O&M Worth
Cost Cost Cost (1)
$0 $O/yr $0
$74,000 $l,oootyr $88,000
$250,000 $'5,000/yr $320,000
$1,000,000 $Otyr $1,000,000
Alternative
No Action
Limited Action
Treatment of
"Direct Contact" Soils
and Placement of
Infiltration Barrier
Treatment of All
Contaminated Soils
$77,000,000 $Otyr
$77,000,000
Notes:
(1) Present worth estimate assumes a 6 percent discount rate and 30
years of 0 & M. Cost estimates in 1994 dollars.
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(2)
The Treatment of "Direct Contact" Soils and Placement of
Inftltration Barrier alternative would cost $2,500,000 if incineration,
rather than biological treatment, was used to treat the 1,000 cubic
yards of contaminated soils.
State Acceptance. The State of Washington has reviewed the soil
alternatives and approved this document and the proposed alternative.
Public Acceptance. The public has had the opportunity to review and
comment on the range of soil alternatives proposed for remedial action at
Site F. The overall supportive public comments received during the
comment period for the Proposed Plan for Final Remedial Action at Site F
and at the public meeting, has been taken as acceptance of the proposed
alternative.
10.2 Evaluation 01 Groundwater Remediation Alternatives by Criteria
Overall Protection of Human Health and the Environment. The No
Action alternative would not provide protection of human health and the
environment, and thus will not be considered further in this evaluation.
The Limited Action alternative would provide protection of human health
by restricting consumption of contaminated groundwater in the Shallow
Aquifer; however, it may not be protective of potential ecological receptors
at the seep if ordnance breakthrough concentrations there exceed chronic or
acute water quality criteria in the future. The Enhanced Groundwater
Treatment alternative would provide protection of human health and the
environment at the seeps and, depending on system performance, may be
effective at. providing overall protection throughout the Shallow Aquifer.
Groundwater treatment by GAC would achieve groundwater RAOs prior to
reintroduction into the Shallow Aquifer.
Compliance with ARARs. The No Action alternative and the Limited
Action alternative would not achieve ARARs for groundwater and would
likely exceed ARARs for surface water in the future at the seeps. The
results of the groundwater modeling indicate that the Enhanced
Groundwater Treatment alternative would likely achieve ARARs; however,
actual system effectiveness may vary from the groundwater model
simulation results. If it is impracticable to achieve all ARARs by the
Enhanced Groundwater Treatment alternative, institutional controls would
be implemented.
Long-Term Effectiveness and Permanence. The long-term effectiveness
of institutional controls implemented under the Limited Action alternative
could be assured as long as the contaminated portion of the Shallow
Aquifer downgradient of Site F remains under the contro. of SUBASE,
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Bangor. The Enhanced Groundwater Treatment alternative provides
long-term effectiveness by using permanent treatment processes.
Reductions in Toxicity, Mobility, or Volume Through Treatment. The
Enhanced Groundwater Treatment alternative provides a permanent
reduction in contaminant toxicity, mobility, and volume. The GAC
treatment includes permanent destruction of contaminants during off-base
regeneration of the used carbon.
Short-Term Effectiveness. The Limited Action alternative would
immediately restrict use of contaminated groundwater within the Shallow
Aquifer downgradient of Site F. The Enhanced Groundwater Treatment
alternative could be constructed relatively quickly by supplementing the
current Site F IRA, which will be operational in 1994.
Implementability. The Limited Action alternative would be easily
implementable since all contaminated groundwater in the Shallow Aquifer
downgradient of Site F is contained well within SUBASE, Bangor
property. There are no water supply wells in the Shallow Aquifer on
SUBASE, Bangor. Because the Shallow Aquifer is not needed for on-base
water supply, SUBASE, Bangor could easily restrict futUre installations of
on-base water supply wells within the zone of groundwater contamination
in the Shallow Aquifer downgradient of Site F. The Enhanced
Groundwater Treatment alternative is readily implementable by enhancing
the current Site F IRA. In addition, this alternative uses a groundwater.
treatment technology (GAC) with demonstrated performance for the
ordnance contaminants present at Site F groundwater.
Cost. The cost of each groundwater remediation alternative, in order of
increasing present worth, is shown below:
Alternative
Capital
Cost
No Action
$0
$40,000
Limited Action
Enhanced Groundwater $2,100,000
Extraction, GAC Treatment,
and Reintroduction
Annual Present
O&M Worth
Cost Cost (1)
$O/yr $0
$21,000/yr $330,000(2)
$160,OOO/yr $3,300,000 to
4,300,000 (3)
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..
Notes:
(1) Present worth cost estimates assumes a 6 percent discount rate.
Cost estimates are in 1994 dollars.
Cost for Limited Action assumes 30 years of monitoring.
Range in cost for the Enhanced Groundwater Treatment alternative
corresponds to an assumed treatment period of 10 to 30 years.
(2)
(3)
State Acceptance. The State of Washington has reviewed the groundwater
alternatives and approved this document and the proposed alternative.
Public Acceptance. The public has had the opportunity to review and
comment on the range of groundwater alternatives proposed for remedial
action at Site F. The overall supportive public comments received during
the comment period for the Proposed Plan for Final Remedial Action at
Site F and at the public meeting, has been taken as acceptance of the
proposed alternative.
11.0 THE SELECTED REMEDY
The alternative selected for the remedial action at Site F includes
Treatment of "Direct Contact" Soils and Placement of an Infiltration
Barrier, and Enhanced Groundwater Extraction, Treatment, and
Reintroduction. This alternative is preferred because it best achieves the
cleanup objectives and fully addresses the risk posed by contamination at
Site F. The remedy employs permanent treatment of contaminants, and
thereby provides long-term protection of human health and the
environment.
The remedial action plan, which will cost an estimated $4.3 to 5.3 million
(present worth) includes the following actions:
11.1 Soil Remediation
~ Excavate contaminated soils to a depth of 15 feet with concentrations
above MTCA Method B residential contact cleanup levels (estimated
soil volume of 1,000 cubic yards).
~ Conduct verification soil sampling during and/or following the
excavation to assure that all soils exceeding the direct contact cleanup
levels to a depth of 15 feet have been excavated. Compliance with the
cleanup standards shall be evaluated using compliance monitoring
procedures which will be described in a compliance sampling and
analysis plan (in accordance with Chapter 173-340 WAC).
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. Physically mix the excavated soils with organic amendment, and place
the soil/amendment mixture into a structure designed specifically to
house the biological treatment process. The type of amendment,
soil:amendment ratio, and other operating parameters (e.g., temperature
and moisture) will be determined during final design. Soils from Site F
and from Site D (Operable Unit 6) may be treated together in a single
process.
. Treatment will be considered completed when ordnance concentrations
in the soil/amendment mixture are below the MTCA Method B direct
contact soil cleanup levels for ordnance (Table 15). Compliance with
the cleanup standards will be determined using compliance monitoring
provisions defmed in Chapter 173-340 WAC. If the biological
treatment does not achieve soil cleanup levels, alternative soil treatment
methods (e.g., incineration) will be evaluated.
. Upon completion of the soil treatment, the treated soil/amendment
mixture will be used to fill and regrade the Site F excavation and
overflow ditch to provide a generally flat surface over which to place
the infiltration barrier.
. Install an inflltration barrier over all soils with concentrations above
soil cleanup levels for protection of groundwater (adjusted for current
PQLs; Table 15). The infiltration barrier is estimated to cover
approximately 2 acres. The type of material used for the barrier will
be decided during fmal design. Depending on the design, the
infiltration barrier may be subsequently covered with uncontaminated
soil both to allow revegetation and to provide greater protection against
physical and chemical (e.g., sunlight) degradation. An operations and
maintenance plan will include periodic inspection of the infiltration
barrier, as needed, to ensure its long-term integrity.
11.2 Groundwater Remediation
. The Site F IRA groundwater extraction, treatment, and reintroduction
system will be enhanced by installation of additional groundwater
extraction wells positioned to provide efficient removal of contaminant
mass from the Shallow Aquifer. Additional granular activated carbon
(GAC) treatment capacity and additional reintroduction wells will also
be added to handle the higher system flow rate. Details regarding
extraction and reintroduction well locations, depths, and pumping rates,
and the enlarged GAC treatment system will be determined during final
design. It is anticipated that a system flow rate of 425 gpm or greater
will be required in the enhanced treatment system to achieve
groundwater cleanup objectives in a reasonable period of time.
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. The objective of the groundwater remediation will be to reduce
contaminant concentrations to below cleanup levels (as defined in Table
15) in Shallow Aquifer monitoring wells at Site F. The objective of the
IRA at Site F, is lirriited to preventing further contaminant migration
(the IRA containment level is different from the cleanup level). .
However, like the IRA, the extracted groundwater will be treated to
meet drinking water standards groundwater cleanup levels prior to its
being returned to the Shallow Aquifer.
. The effectiveness of the Shallow Aquifer restoration program at Site F
will be monitored and evaluated as a component of operation and
maintenance. Water quality data collected as part of the performance
monitoring will be used to evaluate effectiveness and progress of
groundwater remediation relative to established cleanup levels. Trends
in water quality data will also be used to determine whether changes in
system operations, including modifications and enhancements, are
necessary, to improve performance or whether formal review of
continued system operations and potential system shutdown is
warranted. A formal review of continued system operation will be
initiated, after one of the following performance evaluation criteria is
met:
1) Groundwater cleanup levels are achieved for all chemicals
constituents of concern, namely RDX, TNT, DNT, and nitrate at
Shallow Aquifer monitoring wells at Site F; or
2) Groundwater contaminant constituent concentrations are no longer
being reduced (no statistical change in contaminant concentration in
the Shallow Aquifer attributable to system operation) by the
. continued operation of the enhanced groundwater extraction system,. .
after appropriate enhancements and modifications have been made;
or
3) Groundwater contaminant concentrations are declining at a rate such
that the cost of continued enhanced groundwater extraction system
operation, after appropriate enhancements and modifications have
been made, is substantial and disproportionate to the beneficial risk
reduction which would be achieved.
A formal review will be scheduled within one (1) month of the date of
request by the Navy. These performance evaluation criteria will be
considered by the Navy, EP A, and Ecology as part of the formal review,
in determining whether system shutdown or other remedial measures is
warranted. Section 11.6 provides the rationale and basis of the
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performance evaluation criteria including statistical procedures and
practicability considerations, and the specific methodology for evaluating
system performance utilizing these criteria.
11.3 Well Decommissioning
Some groundwater monitoring wells previously installed by the Navy and
the USGS at Site F are no longer of use since they are either screened
. above the current water table or are in close proximity to newer wells.
Furthermore, because well construction documentation for several of these
older wells are lacking, it is uncertain if they were constructed in
compliance with current Washington State well construction regulations.
All such wells will be decommissioned in accordance with Chapter 173-160
WAC, or as approved by Ecology.
11.4 Groundwater Remedial Action Measures and Goals
The goal of the groundwater remedial action is to restore the Shallow
Aquifer waters to support possible future drinking water use. Based on
information obtained during the RI, and the analysis of all remedial
alternatives, the Navy, EPA, and Ecology believe that the selected remedy
will likely be able to achieve this goal. However, the ability to achieve
groundwater cleanup levels at all monitoring wells within the Shallow
Aquifer at Site F cannot be determined until the enhanced system has been
implemented, modified as necessary, and the groundwater extraction
system performance monitored over time.
The selected remedy will include groundwater extraction, treatment, and
reintroduction, during which time the system's perfonnance will be
carefully monitored on a regular basis and adjusted as warranted by the
performance data collected during operation. Modifications may include
any or all of the following:
~ Discontinuing pumping at individual extraction wells where cleanup
goals have been attained;
~ Alternating pumping rates at extraction wells to eliminate stagnation
points; .
~ Pulse pumping to allow aquifer equilibrium and encourage adsorbed
contaminants to partition into groundwater; and
~ Installing additional extraction in the Shallow Aquifer to facilitate or
accelerate cleanup of groundwater contaminants.
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Remedial actions which allow hazardous substances, pollutants, or
contaminants to remain on site must be reviewed not less than every five
years after initiation. to ensure the remedy continues to be protective of
human health and the environment. Performance evaluation criteria, as
presented in Section 11.2, will be used to monitoring system performance
and to determine whether formal review of continued system operation is
warranted. These reviews may result in system shutdown, further
modification of the treatment process, consideration of other remedial
approaches, or revision of the cleanup levels. Changes to the selected
remedy or cleanup levels would require formal notification to the public.
11.5 Effectiveness of Treatment Technology
lJjological Treatment of Soils
Biological treatment is the selected treatment technology for ordnance
contaminants present in excavated Site F soils with concentrations above
direct contact levels (e.g., TNT concentrations above 33 mg/kg). Based on
bench-scale treatability study results, biological treatment will reduce
ordnance concentrations to below direct contact action levels. If upcoming
pilot testing indicates that biological treatment may not be effective for Site
F soils, then incineration will be the back-up treatment technology. .
Incineration has been demonstrated to be effective in treating ordnance
compounds in soils at other military installations.
GAC Treatment of GroundwaJer
Granular Activated Carbon (GAC) is the selected treatment technology for
ordnance contaminants present in groundwater at Site F. It is a proven
technology which has been used extensively at the commercial scale to
remove ordnance compounds from water. Mobile GAC units have been
used to treat Site F groundwater generated d~ring the Site F IRA extraction
well pumping tests to below cleanup levels. Contaminants adsorbed on the
GAC will be permanently destroyed during the thermal regeneration
process conducted off site.
In addition to GAC, extracted groundwater will be treated, as necessary, to
achieve the cleanup level for nitrate. Exceedence of the nitrate cleanup
level may occur during initial system startup. Nitrate concentrations in
treated groundwater are predicted to drop below cleanup levels shortly
after startup.
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11.6 Groundwater Remediation Perfonnance Evaluation Criteria
Based on the results of contaminant transport modeling and preliminary
remedial design analyses, groundwater contaminant reduction is anticipated
to progress from initial removal of the more mobile and aqueous phase
contaminants such as RDX and nitrate, to the less mobile constituents such
as TNT and DNT. Groundwater cleanup standards for RDX will likely be
achieved in a time period of approximately 5 to 10 years (nitrate likely
more rapidly).
As the RDX and nitrate cleanup standards are attained in the Shallow
Aquifer at Site F, the extent of contamination is predicted to decrease
substantially. Subsequent groundwater extraction and treatment efforts will
then focus on the zone of elevated TNT and DNT concentrations in the
Shallow Aquifer, largely restricted to within approximately 1,500 feet of
the former lagoon. Because of this condition, along with uncertainties in
the transport (especially desorption) behavior of TNT and DNT in the
Shallow Aquifer, the groundwater extraction system will likely require
modifications over time to optimize removal of these constituents. Possible
modifications are summarized in Section 11.4.
Practical modifications to the remediation system will be evaluated to
assess whether such improvements would further enhance contaminant
removal. Modifications to the groundwater remediation system will be
made if the evaluation indicates that further contaminant removal is
feasible. Continued modifications will not be required if such
enhancements are shown to be ineffective at further contaminant reduction
or other more practicable solutions are identified. Based on the results of
studies and computer modeling analyses performed to date, and assuming
successful modifications of the groundwater extraction system over time,
TNT and DNT cleanup levels may be achieved within the Shallow Aquifer
at Site F within a time period of 10 to 30 years after system startup. If
groundwater cleanup levels are not achieved, institutional controls andlor
other measures required by EP A and Ecology will be implemented to
protect human health and the environment.
Given current uncertainties in the behavior of chemical transport within the
Shallow Aquifer, it is difficult to predict how well the actual system
performance will match the predicted model results. Consequently,
performance evaluation criteria are provided for establishing when formal
review of the groundwater remediation system operation by the Navy,
EPA, and Ecology, is appropriate. Decision analysis considerations.
including technical feasibility and practicability (disproportionate cost
versus beneficial risk reduction), consistent with the intent of the National
Contingency Plan (NCP) and MTCA, are provided as guidance in
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evaluating whether continued system operation is warranted. The formal
review process will be used to determine the need for contingent
groundwater remedial actions, which may include hydraulic containment or
system shutdown and implementation of institutional controls.
The groundwater remediation system at Site F will be monitored,
evaluated, and modified as appropriate to optimize its effectiveness in
achieving all groundwater cleanup standards. Water quality data collected
as part of performance monitoring will be used to evaluate the effectiveness
and progress of groundwater remediation and provide the basis for
implementing formal review outside of the normal 5-year period. A formal
review to evaluate continued system operation, will be initiated after one of
the following performance evaluation criteria is met:
1) Groundwater cleanup standards are achieved for all chemicals of
concern within the Shallow Aquifer at Site F. Compliance with the
cleanup standards in this case shall be evaluated using compliance
monitormg procedures defined in Chapter 173-340 WAC and EPA's
1992 "Methods for Evaluating Attainment of Cleanup Standards,.
Volume 2: Ground Water", or other applicable future guidance. Based
on the information currently available to forecast system performance,
the Navy, EP A, and Ecology anticipate that the selected remedy will
likely be able to achieve this compliance standard.
2) Constituent concentrations in excess of the groundwater cleanup
standards are no longer being reduced (dermed as no statistically
significant reduction in constituent concentrations in the ShaDow
Aquifer attributable to system operation). In making this
determination, reasonable system enhancements and modifications must
have already been implemented and demonstrated to be ineffective. The '
technical feasibility of further groundwater cleanup will be evaluated in
accordance with EPA's 1993 "Guidance for Evaluating the Technical
Impracticability of Ground-Water Restoration" and other applicable
guidance. The lowest technically achievable concentration shall
represent a "leveled-off" value of contaminant concentration versus
time based on established procedures for regression analysis including
evaluation of uncertainty based on the regression error (analysis of
residual). The specific groundwater compliance monitoring locations
and sampling frequency will be specified by a compliance monitoring
plan to be developed as part of the final system design (post-ROD).
If regression analyses of concentration versus time for data collected
from the compliance monitoring wells reveal that the slope of the curye
is not different from zero at the 95 percent confidence level (based on
Students-t test), then a formal review of continued system operation
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will be initiated. If the system is shutdown following review and
concurrence by EP A and Ecology, institutional controls and/or other
measures required by EP A and Ecology will be implemented to protect
h1:lman health and the environment. Long-term water quality
monitoring will be required until groundwater cleanup levels are
attained in the Shallow Aquifer at Site F.
3) CoDStituent concentrations in excess of the groundwater cleanup
standards are declining at such a slow rate that the incremental cost
of continued groundwater extraction system operation is considered
to be substantial and disproportionate to the incremental degree of
environmental protection. This determination will be based on an
evaluation of water quality monitoring data, overall system performance
including appropriate enhancements, potential risk posed by leaving
residual contaminants in-place, and cost of continued operation.
Given the uncertainty in actual system performance, the Navy, EP A,
and Ecology have established 30 years as a reasonable maximum period
of system operation. However, information collected during system
operation, after reasonable measures are taken to enhance system
performance, may support system shutdown within a shorter timeframe,
based on impracticability, within the meaning set forth in the NCP and
MTCA.
The general analysis will be based on a comparison of risk reduction
(incremental environmental protection) versus incremental cost for
continued system operation versus other remedial response measures
which may include lower preference alternatives such as institutional
controls. This analysis will be consistent with the methodology for
comparative analysis of remedial alternatives presented in the Site F
Final Remedial InvestigationlFeasibility Study (RI/FS), dated
November 1993, and as a component for remedy selection in the
Proposed Plan for Remedial Action, dated February 1994.
The Navy may request a formal review if continued system operation
can be demonstrated to be impracticable. The formal review will be
initiated to determine whether system operation should continue or
whether other more practicable remedial response actions are
warranted. If the system is shutdown following review and
concurrence by EPA and Ecology, institutional controls and/or other
measures required by EP A and Ecology will be implemented to protect
human health and the environment. Long-term water quality
monitoring will be required until groundwater cleanup levels are
achieved in all monitoring wells in the Shallow Aquifer at Site F.
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1-3947-03
12.0 STATUTORY DETERMINATIONS
The remedial action for implementation at SUBASE, Bangor, Site F
(Operable Unit 2) is consistent with CERCLA and, to the extent
practicable, the NCP. The selected remedy is protective of human health
and the environment, attains ARARs unless technically impracticable, and
is cost effective. The selected remedy also satisfies the statutory
preference for treatment which permanently and substantially reduces
mobility, toxicity, or volume of contamination as a principal element.
Additionally, the selected remedy uses alternate treatment technologies or
resource recovery technologies to the extent practicable.
12.1 Protection 01 Human Health and the Environment
The selected remedial action will protect human health and the environment
through permanent treatment of soils to eliminate direct contact risk,
insta.1lation of an infiltration barrier to prevent further impacts to the
Shallow Aquifer from residual contaminated soils, and extraction and
treatment of ordnance in groundwater. The ~ent standards support the
highest beneficial use of these media (Le., residential land use and water
supply), and are protective of human health and the environment. The
ordnance contaminants will be permanently removed from the. soil by
biological degradation to less toxic byproducts, and from groundwater by
adsorption to activated carbon with permanent destruction during thermal
regeneration. As necessary, groundwater will be further treated for nitrate
to ensure that the treated water meets all RAOs prior to its return to the
Shallow Aquifer.
12.2 CompliJJnce wiJh Applicable or Relevant and Appropriole Requirements .
The selected remedy will comply with all applicable or relevant and
appropriate chemical-, action-, and location-specific requirements
(ARARs). The ARARs are presented below.
Action-Spec(fic ARARs
. State of Washington Hazardous Waste Cleanup - Model Toxics Control
Act (Chapter 70.105D RCW) establishes requirements for the
identification, investigation, and cleanup of facilities where hazardous
substances have come to be located as codified in Chapter 173-340
WAC.
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J-3947-03
~ Requirements of the State of Washington for water well construction as
set forth in Chapter 18.104 RCW (Water Well Construction) and
codified in Chapter 173-160 WAC (Minimum Standards for
Construction and Maintenance of Wells), establishes criteria for the
construction of extraction and compliance monitoring wells. Criteria
for Class V reintroduction wells are set forth in Chapter 90.48 RCW
and codified in Chapter 173-218 WAC.
~ The State of Washington has established requirements for control of
fugitive dusts and other air emissions during excavation and cleanup
related activities, as codified in WAC 173-400-040.
~ The State of Washington has established safe operating procedures and
requirements for hazardous waste operations conducted at uncontrolled
hazardous waste sites, as set forth in WAC 296-62 (Part P).
~ Federal Clean Water requirements for discharge of treatment system
effluent to the waters of the United States, as set forth in 40 CFR 122,
establish design standards for wastewater treatment units.
~ Water Pollution Control Act (Chapter 90.48 RCW) and Water
Resources Act of 1971 (Chapter 90.54 RCW) require the use of all
known available and reasonable methods (AKARMs) for controlling
discharges to surface water and groundwater. This regulation will
apply to excavation activities at Site F and will require that "best
managemen,t practices" be applied during these activities.
~ The State of Washington Hazardous Waste Management Act (Chapter
70.105 RCW) establishes requirements for dangerous waste and
extremely hazardous waste as codified in Chapter 173-303 WAC and
may apply depending upon any treatment residuals created. No
dangerous wastes have been identified to date.
~ Federal Resource Conservation and Recovery Act (RCRA). Transport
of GAC will be conducted in accordance with all applicable local, state,
and federal transportation regulations. Fresh GAC transported onto the
site will not be a hazardous waste and standard shipping regulations
will apply. Spent GAC will be managed as a K045 hazardous waste.
(K045 is the hazardous waste number assigned under RCRA for spent
carbon from the treatment of wastewater containing explosives.) A
limit of ten percent (10%) by weight explosives loading on the GAC to
be sent off site is set in order to ensure that the GAC will not be a
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J-3947-o3
characteristic RCRA hazardous waste for reactivity. In addition, spent
GAC will be evaluated to determine if it exhibits the toxicity hazardous
waste characteristic (e.g., due to 2,4-DNT content). This evaluation
will include testing if necessary. Spent GAC will be manifested and
transported in accordance with all applicable regulations.
In order to ensure that the off-site thermal treatment does not contribute to
present or future environmental problems, the selection of a thermal
treatment facility will follow the procedures presented in Procedures for
Planning and Implementing Off-Site Response Actions, 58 FR 49200,
September 22, 1993.
Regeneration of spent GAC will be performed at a facility permitted to
accept hazardous waste. If a specific batch of spent GAC is not accepted
for thermal regeneration (due, for example, to an unacceptably high
ordnance loading), it will eith~ be used as a supplemental fuel in a cement
kiln or, as a last resort, incinerated. In any case, only a facility permitted
to accept hazardous waste will be used.
The selected remedy will not involve the placement of RCRA hazardous
wastes on site.
Soil and groundwater remediation activities will meet the following
chemical-specific ARARs:
~ State of Washington Hazardous Waste Cleanup - Model Toxics Control
Act (MTCA; Chapter 70.10SD RCW) establishes requirements for the
identification, investigation, and cleanup of facilities where hazardous
substances have come to be located as codified in Chapter 173-340
WAC. Soil and groundwater cleanup standards established under the
MTCA are applicable for determining remediation areas and volumes
and compliance monitoring requirements, and are relevant and
appropriate for determining treatment standards.
~ State of Washington Groundwater Quality Standards (WAC 173-2(0)
are applicable chemical-specific standards for water reintroduced to the
Shallow Aquifer.
~ Ambient concentrations of toxic air contaminants are regulated pursuant
to the State of Washington Clean Air Act (Chapter 70.94 RCW) and
Implementation of RegUlations for Air Contaminant Sources (Chapter
173-403 WAC).
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J-3947-03
. The State of Washington Hazardous Waste Management Act (Chapter
70.105 RCW) establishes requirements for dangerous waste and
extremely hazardous waste as codified in Chapter 173-303 WAC. This
regulation designates those solid wastes which are dangerous or
extremely hazardous to the public health and the environment; provides
surveillance and monitoring requirements for such wastes until they are
detoxified, reclaimed, neutralized, or disposed of safely; and establishes
the siting, design, operation, closure, post-closure, fmancial, and
monitoring requirements for dangerous and extremely hazardous waste
transfer, treatment, storage, and disposal facilities.
~on-Spec~fic ARARs
There are no location-specific ARARs for this action.
Other Crit~es. or Guidance 'ffl=Pe-Considered rTBC)
. Ecology's "Statistical Guidance for Ecology Site Managers" (August
1992), and supplements to it (e.g., August 1993), as well as EPA's
"Methods for Evaluating the Attainment of Cleanup Standards" (July
1992) are TBC guidance for monitoring of this remedial action.
12.3 Cost Effectiveness
The selected Remedial Action is cost-effective because it is protective of
human health and the environment, achieves ARARs, and its effectiveness
in meeting the objectives of the selected remedial action is proportional to
its cost. The soil remediation component of the selected remedy is
substantially more cost-effective than excavating all contaminated soils,
while achieving the same sUbstantive risk reduction. The selected remedy
can be implemented in the short-term.
12.4 Utilization of Permanent Solutions and Alternative Treatment Technologies or
Resource Recovery Technologies to the Maximum Extent Practicable
The Navy, the State of Washington, and the EPA have determined that the
selected remedy represents the maximum extent to which permanent
solutions and treatment technologies can be used in a cost-effective manner
for Site F. Biological treatment of contaminated soils is an innovative
treatment technology that will result in the on-site destruction of
contaminants in the selected remedy. In addition, reintroduction of the
extracted and treated groundwater will replenish the groundwater resource.
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J-3947-03
12.5 Preference for Treatment as Principal Element
By treating ordnance contaminants present in soil and groundwater media,
the statutory preference for remedies employing treatment as a primary
element is achieved. The selected remedy will result in on-site destruction
of contaminants in both soil and groundwater.
13.0 DOCUMENTATION OF NO SIGNIFICANT CHANGES
The Navy, EP A, and Ecology released the Site F proposed plan (preferred
. remedial alternative) for public comment on January 21, 1994. The
preferred alternative presented in the proposed plan is the same as the
selected alternative presented in this Record of Decision. The Navy, EPA,
and Ecology reviewed all written and verbal comments submitted during
the public comment period. Upon review of those comments, it was
determined that no significant changes to the remedy, as it was originally
identified in the .proposed plan, were necessary.
silCfrod.fm
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J-3947-03
Table 1 - Summary of Chemicals of Concern for Site F
Compound Name
Rangc of Soil
Concentrations in mg/kg
Rangc of Groundwater
Concentrations in p.g/L
1,3,5- Trinitrobcnzene
1,3-DiDitrobcDzenc
2,4,6- Trinitrotoluene
2,4-DiDitrotoluenc
2,6-DiDitrotoluenc
RDX
Manganese
Nitrate + Nitrite
,.
0.004 U to 17
0.004 U to 0.27
0.002 U to 1,500 J
0.002 U to 3.6
0.002 U to 0.41
0.005 U to 20
0.15 to 0.35
0.54 U to 17
0.022 U to 1,000
0.026 U to 61 J
0.008 U to 1,800,000 I
0.018 U to S40
0.001 U to 44 I
0.011 U to 7,120 J
2.4 to 809
30 to 94,000
U - Not detected at indicated detection limit.
J - Estimated concentration.
'''1IIJ\T8k1.wlta
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Table 2. - Basis for Selecting Exposure Pathways for Quantitative Risk As5fosgnent
~of
&po.ae CD PIIIIIway
CIIaIaic:U iD ScIec:taI Cor
Aft'ecad Media Aft'ecad Q\o8liII~re
...... RIapIDn Media E¥UIIIioD B8aiI Cor SeIecdaa or &clulioa
lIME It&8ida8 Air - wpon IabUIioD No Cbcmic:aII cia DOt r&8Iily voIIdiIizL
(II........ Lie MuiaIaID
&po.ae Sc:a8rio . paaple Air- Iab8IIIioG V.. RI8idCDII may iDbaJe cbaaicaIo ---- CD wiDdlllowacllllc
Ii¥iII8 _dID .. - ... WaIbIowD DuIt wbicb are rdaIaI r- cii8IurtIed ----nee
..--4w8lUad 0Iba' 1OiII.
~..;'~ftIIOUI'CD iD
dID -.> sun- Soil IDpI8ioD V.. RI8idCDII_y bave - CD -----.... -moo ocri8.
Daa8I V.. RI8idCDII may bave - CD 00""--' '..r- 8OiIa.
COIII8Ct
o-a sun- lDcalioD No Oo-lile ourf8cc --. wbicb oaIy poada taIIpOI8rily iD doc
w~ - _. it of ~qu8DIiIy for -. cIriakiat
'II/8Ia'.
IDbUdioG No ID8ipificut ~ p81bway. l..imiIeII qI8DIity of WIB
cxiI1a oaIy iD dID - - - cbaaicaIo of ~
- are DOt volllilo.
Daa8I No 1aIipific8II1~ p81bway. l..imiIeII q-*Y of WIB
COIII8Ct aiIIa oaIy iD dID - - - c:oot 1r:IIIpCnIIIft8 wiD
miDimize~
OD-Sitc IapdoD . V.. Raida118 -y drialt -= r- fusure wdIt cgapIdIIIt-
~ 8itc iD die 8baIIow 8q1Iifc:r.
Iab8IIIioG No No volllik: c:bcIIIic:aII- idaIIifiaI. Pu EPA ItqiaD 10
SuppiaDallll RiIk ~ - ... Guid8Dco for 8IIpCIfuad
(Au,. 16. 1991). DO cbaaicaIo wen: idcaIifiaI iD
J1'CI'IIIIIw8Iewdb H>I~uod MW<200.
ea-t V.. Cbcmic:aII may be 8b.oItIed duvqhlkiD wbaa ~
C- it uoed Cor buIIiDa.
OfI'-Sitc Sarfw:c IqC8Iioa No AJIboqboff..itc. cIowa8nd-~ 'II/8Ia' -W- bavc
W~ Seepa "-1IICId u . driakiq - - iD 1be .-. dIaDic81
..-:caInIioaII81111 --- ri8t via dIiI padIway are
coaeiderably lower d8a1be CIIHiIIe JftIIIIIIdWllerp8lllw8y
IUIIDarizaI abav~ (81111 ~ Cor qu8lllil8dveC¥&III8IiaD).
IabaIaIiaD No IaIipific8II1 ~ p81bway. COIIIpU'CIII willa -- 8ir
apc8Ift8. c:baIIic:al ,ma ",......81111 ~
&cquaIciI8 are IIIIICb leu.
Daa8I No 1aIipific8II1~ p81bway. COIIIpU'CIII willa --1Oil
COIII8Ct apcI8IIftII. c:baIIic:al..-.."" - - ~
~are much leu.
AquaIic V.. Em1iDI filii babilat it extrc:IIIdy IiIIIiIaI iD 1be ..,
0rpai8m di8dIu1~ -- Puhway - ~ CD - ri8t8
IDcClllioa _iaIed wilb pouible fusure babilat improvaDcaL
TenaIria1 No la8ufficiaat ~of 1oca1 tenaIria1 orpaia8
0rpai8m occ:un CD - 811 iDvl8liplioDofdlil pIIbw8y. No
IDcClllioa COVidCDCC Ib81 onID8IIcc c:baIIic:ale IlCe'ftu"'" iD plaall or
tenaIriaI aa.imaI8.
W8l« - Soil NODe V.. RaidCIID -y bav~ - CD _.....;"....1 lOiIe leu dim
iD Vadoee Zoac IS feu below a1'OUIId eumcc.
394703\T ABU1..2
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Table 3 - Inhalation of Chemicals in Air by Potential Residents
Equation:
17JtDk.e (m ./'--,,1,....\ - CA%lRxEFxED
g/AfJ WMJ) - BW%ATxCF
Values for equation variables:
Exposure Factor Units Average RME
Condition- Condition-
Chemical Concentration mg/m3 Calculated Calculated
Air - soil dust (CA) Valueb Valuec
Inhalation Rate (IR) m3/day 20 20
Exposure Frequency (EF) days/year 275 350
Exposure Duration (ED) years 9 30
Body Weight (BW) kg 70 . 70
Averaging Time (AT):
noncarcinogenic effects years 9 30
carcinogenic effects years 70 70
Correction Factors (CF) days/year 365 365
Notes:
. Exposure factors for the average and RME exposure scenarios obtained from EP A Region
10 Supplemental Risk Assessment Guidance for Superfund, August 16, 1991.
. b Average concentrations of validated surface soil data for samples collected in the. .
overflow ditch area, in conjunction with models as discussed for reference c.
c Upper 95th percent confidence interval concentrations about the average of validated
surface soil samples collected in the overflow ditch area, in conjunction with
environmental chemical transport m9dels presented in Rapid Assessment of Exposure to
Particulate Emissions from Surface Contamination Sites (EPA/600/8-85-002). The model
addresses fugitive dust emissions within the 0.1 acre contaminated area.
394703\T8bIc.3
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Table 4 - Ingestion of Chemicals in SoU by Potential Residents
Equation:
Intake (mg/kg-day) = CSxlRlxCFAxEF%EDl + CS%lR2%CFAxEF%ED2
BW1%A1'%CFB BW2rAT.rCFB
Values for equations variables:
Exposure Factor Units Average RME
Condition. Condition.
Chemical Concentration Soil (CS) mglkg Average 95 % UCL
Concentrationb Concentrationb
Ingestion Rate: mg/day
Child (0-6 yrs) (IRl) 0 200
Adult (IR2) 100 100
Conversion Factor A (CF A) kgImg 1
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Table S - Dermal Contact and Subsequent Absorption of Chemicals in SoU by Potential
Residents
Equation:
Intll1ce = CSxSA1xCFAxAF%ABSxEFxEDl + CSxSA2%CFAxAF%ABSxEF'xED2
(mg/kg-day) BWl%A1'%CFB BW2xA1XCnI
Values for equations variables:
ExpoIure Factor Vaila Avorap RME
CODditiosf CoIIdition"
Chemical C~ Soil (CS) maItI AVer8p 95$ VCL
Ccmcemr8tioo' COIICCDIr8tioD'
SkiD Surface Ala Available for Conuct qlday
Child (0-6 yn) (SAl) 0 3.900
Aduh (SA2) 1900 3,450
Conversion Factor A (CPA) q/mg 1()4 1()4
SoilISkin Adherem:o Factor (AP) qlCrtr 1.0 1.0
Absorpuon Factor (ABS):
mctaIa $ by Wt. C1 C1
orpaic:. 50- 50-
Expo8ure Frequency (EF) day/yr 175 350
ExpoIure Duration:
Child (0-6 yn; EDl) year 0 6
Adult (EM) 9 14
BodyWeipt:
CbiId (0-6 yn; BWl) q - 15
Aduh (BW1) 70 70
Averaging lame (AT): year
DOD-C8rI:iDosenic effects 9 30
carciDosenic effects 70 70
ConectiOD Factor B (CFB) day/year 365 365
c.
d.
e.
Expo8ure fiactoll for Ibe aVer8p and RME lCenario .,., obtaiDed from EPA ReJioo 10 Supplemenl8l Riak As~ Guidance
for Supcrfimd. AuJUlt 16, 1991.
Averap II1II upper 95th percent coufideoce iDterval coocCllll'8tioaa about the aver8p of validalcd data for IUl'face soil samples.
AvoraJO for IIIIDJDe1' (5,000 car) and wiDrer (1900 car) RME exposure f'actoll.
Cadmium baa an absorptioD factor of 1 $.
An upper-bouDd default dermal abSOrptiOD wu IllUmed basc:d on Hunt (1991), which ilalso consistent with model predictioaa
UIiDa EPA ReJiOD 10 Supplemental Risk AIIe-nt Guidaoce for Superfund.
8.
b.
394703\Tablc.S
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Table 6 - Ingestion of Chemicals in Drinking Water by Potential Residents
Equation:
Int4ke (mglkg-day) = CWxlRxEF%ED
BWx.47%CF
Values for equation variables:
Exposuxe Factor Units Average RME
Condition- Condition-
Chemical Concentration mg/liter Average 95" UCL
in Water (CW) Concentrahonb Concentrab.onb
Ingestion Rate (IR) liters/day 1.4 2.0
Exposure Frequency (EF) days/year 275 350
Exposure Duration (ED) years 9 30
Body Weight (BW) kg 70 70
Averaging Time (AT):
noncarcinogenic effects years 9 30
carcinogenic effects years 70 70
Comction Factor (CF) days/year 365 365
Notes:
Exposure factors for the average and RME exposure scenarios obtained from EPA Region 10
Supplemental Risk Assessmellt Guidance for Superfund, August 16, 1991.
Validated data used to determine average and RME groundwater concentrations for samples collected at
Well F-MW31. .
b
394703\Tablc.6
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Table 7 - Dermal Absorption of ChemiCals in Water by Potential Residents
Equation:
I1JtiZke (mglkg-day) = CWxSAxPCxETxEF%ED%CFA
BWxA7iCFB
Values for equation variables:
Exposure Factor Units Average Condition- RME Condition"
Chemical Concentration mglL Average 95 % UCL
Water (CW) Concentration" Concentration"
Conversion Factor A (CF A) liters/cur 10"3 10"3
Skin Surface Area Available for cur 20, ()()() 20,000
Contact (SA)
Dermal Petmeability Constant
(PC):
metals cmIbr 0 0
ordnance and other organics cmIhr calculated value" calculated value"
Exposure Time (ET) hours/day 0.12 0.17
Exposure Frequency (EF) days/year 275 350
Exposure Duration (ED) years 9 30
Body Weight (BW) kg 70 70
Averaging Time (AT):
nonc:art:inogenic effects years 9 30
carcinogeoic: effects years 70 70
Correction Factor B (CFB) days/year 365 365
Notes:
It
Exposure factors for the average and reasonable maximum exposure scenarios obtained &om EP A
Region 10 Supplemental Risk AssessIIient Guidance for Superfund, August 16, 1991.
Validated data used to determine average and RME groundwater concentrations for samples collected at
Well F-MW31.
Calculated based on EPA Region 10 Supplemental Risk Assessment Guidance for Superfund.
-
"
~'m\T ABL.E.1
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Table 8 - Ingestion of Chemicals in FJShIShellf"lSh by Potential Recreational Users
Equation:
IntDke (mg/kg-dlJy) = CSWxBCF:rFCRxFDF:rED
BWzA7%CFAxCn
Values for equations variables:
Exposure Factor Units Average RME
Condition. Condition.
C~~~Co~~~tiooSmfa~ I£glL Average 95% UCL
water (CSW) Conc. b Conc. b
Biocon~n~tion Factor (BCF) unitless Chemi~ Che~~
SpecifiCC Specificc
Fish Consumption Rate (FCR) glday 6.5d 54c
Fish Diet Fraction (FDF) unitless 0.5f 0.5f
Exposure Duration (ED) years 9 30
Body Weight (BW) kg 70 70
Average Time (AT):
non-carcinogen year 9 30
carcinogen 70 70
Correction Factor A (CFA) #£g/mg 1,000 1,000
Correction Factor B (CFB) glL 1,000 1,000
a. Exposure factors for the average and RME scenario are obtained from EP A Region 10
Supplemental Risk Assessment Guidan~ for Superfund, August 16, 1991.
b. Average and upper 95th percent confid~~ interval concen~tions based on contaminant
transport modeling.
c. See Table 7-8 in Site F RIfFS.
d. Based on Section 304 of Clean Water Act.
e. Based upon EPA (1991d) "Standard Default Exposure Factors".
f. Based on Chapter 173-340-730 WAC, which establishes regional exposure factors for fish
co~sumption.
394703\Table.8
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Table' - FISh Bioc:oncentration FactorS for Chemicals of Potential Concern
Chemical BCF Reference
Barium - No Data
Beryllium 19 IRIS
Cadmium 64 IRIS
Chromium 16 IRIS
Copper 36 IRIS
Cyanide 1 IRIS
Manganese - No Data
Mercury 5500 IRIS (freshwater)
Nickel 47 IRIS
Nitrate - No Data
Nitrite - No Data
. Silver 0.5 IRIS
Zinc 47 IRIS
RDX 2.9 Geometric Mean of BCFs reported
by Etnier, 1986.
2,4,6-TNT 9.5 Value for fish muscle reported
by Liu et al., 1983.
2,4-DNT 3.8 IRIS
1,3,5-TNB 3.0 Based on log K- regression..
1,3-DNB 6.0 Based on log K- regression..
Nitrobenzene 2.9 IRIS
2,4-DNP 1.5 EP A, 1992a
~otes:
IRIS: Integrated Risk Information System, March 1991.
a. From Layton et al. (1987). Conventional Weapons Demilitarization: A Health and
Environmental Effects Database Assessment. Lawrence Livermore National
Laboratory, University of California - Berkeley. Supported by U.S. Army Medical
. Research and Development Command.
394703\TABLE.9
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Table 10 - keference Doses for Chemicals of Potential Concern
Oral Exposures Inhalation Exposures
Reference Dose Uncertainty Species Reference Dose Uncertainty Species
Chemical in mglkg-day Factor Tested Target Organ/Effect Reference in mglkg-day Factor Tested Target Organ/Effect Reference
Metals and Inorgani~s
Aluminum ND ND IRIS
Barium 7.0E-02 3 human hypertension IRIS 1.0E-04 1,000 rat fetotodcity HEAST
Beryllium S.OE-03 100 rat no effect IRIS ND IRIS
Cadmium (water) 5.0E-04 10 human renal proteinuria IRIS ND IRIS
Cadmium (food) I.OE-03 10 human renal proteinuria IRIS ND IRIS
Chromium III I.OE+OO 100 rat no effect IRIS 5.7E-07 300 rat nasal mucosa atrophy HEAST '91 (a)
Chromium VI 5.0E-03 500 rats no effect IRIS 5.7E-07 300 rat nasal mucosa atrophy HEAST '91 (a)
Copper 3.7E-02 NA human 0.1. Irritation HEAST ND IRIS
Lead ND IRIS ND IRIS
Manganese 5.0E-03 I human central nervous system IRIS 1.1 E -04 300 human respiratory, psychomotor IRIS
Mercury 3.0E-04 1,000 rat kidney HEAST 9.0E-oS 30 human neurotoxicity HEAST
Nickel 2.0E-02 300 rat decreased body/organ weight IRIS ND IRIS
Silver 5.0E-03 3 human skin discoloration IRIS ND IRIS
Zinc 2.0E-01 10 human anemia IRIS ND IRIS
Cyanide 2.0E-02 100 rat wt. loss, thyroid, myelin IRIS ND IRIS
Nitrite I.OE-ol I human infant blood IRIS ND IRIS
Nitrate 1.6E+OO I human infant blood IRIS ND IRIS
Ordnance
RDX 3.0E-03 100 rat prostate IRIS ND
2,4,6-TNT 5.0E-04 1,000 dog liver IRIS ND
2,4-DNT 2.0E-03 100 dog neurotoxicity IRIS ND
2,6-DNT ND ND ND ND IRIS ND
1,3,5-TNB S.OE-oS 10,000 rat splcen IRIS ND
1,3-DNB 1.0E-04 3,000 rat splcen IRIS ND
Nitrobenzene 5.0E-04 10 ,000 rat, mouse blood, kidney, liver, adrenal IRIS . 5.7E-04 3,000 mouse blood, kidney, liver, adrenal HEAST
Picrainic Acid ND IRIS ND IRIS
Picric Acid ND IRIS ND IRIS
Tetryl ND IRIS' ND IRIS
Other Organics
2,4-Dinitrophenol 2.0E-03 1,000 human eye cateracts IRIS ND
Di-n-octylphthlate 2.0E-02 1,000 rat liver, kidney HEAST ND
'1:1
~
(JQ
(11
VI
-
ND Not yet determined by the EP A.
a) The inhalation RIDs for chromium were removed.from HEAST (1992).
HEAST: Health Effects Assessment Summary Tables, 1992.
IRIS: Integrated Risk Information System, March 1991.
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Table II - Slope Factors for Chemicals of Potential Concern
Oral Expolurca Inhelalion Exposures
Cancer Slope Factor SpeclCl Slope Factor Species
Chemlcel Group (mglkg-day)-I Tcstcd Target Organ (mg/kg-day)-I Telted Target Organ Reference
McteJs and Inorganlcs
Aluminum NE NA NA
Barium NE NA NA
Beryllium B2 4.3E+OO rat total body 8.40E+OO human lung IRIS
Cadmium BI NA 6.IE+OO human respiratory tract IRIS
Chromium III NE NA NA
Chromium VI A NA 4.2E+01 human lung IRIS
Copper D NA NA IRIS
Lesd B2 NA NA IRIS
Mangancac D NA NA IRIS
Mercury D NA NA IRIS
Nickel (refinery dust) A NA 8.40E-01 human respiratory tract. HEAST
Silver D NA NA IRIS.
Zinc D NA NA IRIS
Cyanide D NA NA IRIS
Nitrite NE NA NA IRIS
Nitrate NE NA NA IRIS
Ordnance
RDX C 1.1 E-o I mousc liver NA IRIS
i,4,6-TNT C 3.0E-02 rat urinary. bladder NA IRIS
2,4-DNT B2 6.8E-01 rat liver. mammary gland NA IRIS
2,6-DNT B2 6.8E-01 rat liver. mammary gland NA IRIS
1,3,S-TNB NE NA NA
1,3-DNB NE NA NA
Nitrobenzene D NA NA
Picramlc Acid NE NA NA
Picric acid NE NA NA
Tctryl NE NA NA
Other Organics
2,4-Dlnltrophenol NE NA NA
DI-n-octylphthlate NE NA NA
Noles:
B2 Probable human carcinogen.
C Possible human carcinogen.
D No cIasslflable 81 to human carcinogenicity.
NE Not yet evaluated for carcinogenicity by EPA.
NA Not applicable, not eveluatcd by EPA, and/or not a carcinogen.
HEAST: Health Effects Asscssment Summary TablC8, 1992..
IRIS: Integrated Risk Information System, March 1991.
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Table 12 - Calculated Hazard Quotients for Site F Baseline Exposure Assumptions
Dust InhalaUoo Sollln&eltlOll Dermal Coatact Water lDeeltlOll Water Coatact Plab lDeeltiOll CUmulltive HUlrdlDclcs
A verlle RMI! A verlle RMB Avenle RMB Aven,e RMB Avenle RMB A verlle RMB Averlle RMB
Metall and IoOlllo1cI
Barium <0,1 <0,1 <0.1 <0.1 <0.1 <0,1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1
Cldmlum <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0,1 <0.1 <0.1 <0.1 <0.1 <0.1
Chromium <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 ~.I <0.1 <0.1 <0.1 <0.1
Copper <0,1 <0.1 <0.1 <0.1 <0.1 <0,1 <0.1 <0.1 <0.1 <0,1 <0,1 <0,1 <0.1 <0.1
Cylo1de <0.1 <0,1 <0.1 <0.1 <0.1 <0.1 0.1 0.1 <0.1 <0.1 <0,1 <0.1 0.1 0.1
Leld <0.1 <0.1 <0,1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 C».I
MlnllDelC <0.1 <0,1 0.1 0.3 <0.1 <0,1 0.9 1.7 <0.1 <0.1 C».I <0,1 1.0 1.0
Mercury <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1
Nickel <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1
Nllrlle-N <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 1.7 ".5 <0.1 <0.1 <0.1 <0.1 1.7 ".5
Nllrlle-N <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 1.0 1.1 <0.1 <0.1 C».I <0.1 1.0 2.2
Silver <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0,1 <0.1 <0.1
Zinc <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1
Ordnance
RDX <0.1 <0.1 <0.1 <0.1 <0.1 0.3 1 9 <0.1 0.1 <0.1 C».I 2 .9
2.",6- Trlnllrotolucne <0.1 <0.1 0.9 7 15 81 187 510 5.0 13.0 0.1 0.6 208 61.
2.4- DlnitrotolucDe <0.1 <0,1 <0.1 C».I <0.1 <0.1 3 8 0.2 0." <0.1 <0.1 .. 8
2.6-Dinilrotolucnc <0.1 <0,1 <0.1 <0.1 <0.1 C».I <0.1 <0.1 <0,1 <0.1 <0.1 <0.1
1.3,5- Trlnilrobenzenc <0.1 <0.1 <0.1 0.1 0.2 0.9 72 170 2.0 5.5 <0.1 0.1 75 176
1,3- Dlnllrobcnzcnc <0.1 C»,I <0.1 <0.1 <0.1 0.5 5 17 0.1 0." <0,1 <0.1 S 18
Nllrobenzene <0.1 <0,1 <0.1 <0.1 <0,1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 C».I
Otlo Puel <0.1 <0.1 C».I <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 C».I
Plcrlmlc Acid <0.1 <0,1 <0.1 <0.1 <0,1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 . <0.1
Picric Acid <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 C».I <0.1 <0.1 <0.1 <0,1 <0.1
Telryl <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0,1 <0.1 <0.1 C».I C».I <0.1 <0.1 <0.1
Scmlvoillile Olllo1cI
1,"-Dlnltrophenol <0.1 <0,1 <0.1 <0.1 <0,1 <0,1 <0.1 <0,1 <0.1 <0.1 <0,1 <0.1 <0.1 <0.1
DI-n-ocl)'1 pbthliite <0,1 <0.1 <0.1 <0,1 <0.1 <0.1 <0.1 <0.1 C».I <0.1 <0.1 <0.1 <0.1 C».I
TOTAL HAZARD INDEX <0.1 <0.1 0.9 8 U 89 173 721 7 19 0.1 0.7 'WI 131
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Table 13 - Calculated Lifetime Cancer Risks for Site F Baseline Exposure Assumptions
Dust Inhalation son Ingestion Dermal Contact Water Ingestion Water Contact Fish Ingestion CUMULATIVE CANCER RI
Average RME Average RME Average RME Average RME Average RME Average RME Average RME
Metals and Inorganlcs
Barium
Cadmium 6E-IO 3E-09 OE+OO OE+OO OE+OO OE+OO OE+OO OE+OO OE+OO OE+OO OE+OO OE+OO 6E-IO 3E-09
Chromium IE-07 4E-07 OE+OO OE+OO OE+OO OE+OO OE+OO OE+OO OE+OO OE+OO OE+OO OE+OO 1E-07 4E-07
Copper
Cyanide
Lead
Manganese
Mercury
Nickel 3E-09 IE-oS OE+OO OE+OO OE+OO OE+OO OE+OO . OE+OO OE+OO OE+OO OE+OO OE+OO 3E-09 IE-oS
Nitrate-N
Nitrlte-N
Silver
Zinc
Ordnance
RDX 2E-IO 6E-IO SE-oS 3E-06 IE-06 4E-oS 9E-oS IE-03 7E-07 9E-06 9E-07 SE-06 9E-oS IE-03
2.4.6-Trinitrotoluene 4E-09 9E-09 2E-06 SE-oS 3E-oS 6E-04 4E-04 3E-03 9E-06 SE-oS 4E-07 4E-06 4E-04 4E-03
2,4-Dinltrotoluene 3E-11 SE-II 2E-oS 4E-07 3E-07 SE-06 2E-oS 3E-04 SE-07 9E-06 2E-oS 2E-07 3E-oS 3E-04
2.6-Dinitrotoluene IE-IO 2E-IO SE-08 IE-06 8E-07 IE-05 6E-04 4E-03 3E-oS 2E-04 4E-07 4E-06 6E-04 SE-03
1.3.S-Trinitrobenzene
1.3-Dinltrobenzene
Nitrobenzene
Otto Fuel
Plcramic Acid
Picric Acid
T etryl
SemivolatUe Organics
2 ,4-Dinitrophenol
Di-n-octyl phthalate
CUMULATIVE CANCER 1E-07 SE-07 2E-06 SE-oS 3E-05 6E-04 IE-03 9E-03 4E-oS 3E-04 2E-06 SE-06 IE-03 1E-02
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Hart Crowser
J-3947-o3
able 14 - Summary of AssumptioDS and Uncertainties in the Baseline Human Health Risk
Assessment Sheet 1 of 3
Area of Uncertainty Assumption Made Likely Effect Rationale
on Site Risk
Selecting Inorganic Except for arsenic, all Slightly At least some component
CheancdsofPotenti& inorganics result from spills in Overestimated of inorganic
Concern the dispow lagoon concentrations are from
natural background.
Inorganics generally pose
negligible risk at Site F.
Exposure Scenario Residential Use of Groundwater Highly Water supplies at
Overestimated SUBASE, Bangor are
derived from the Sea
Level Aquifer or Deeper
Aquifers, which are
isolated from the Shallow
Aquifer by one or more
aquitards.
Dermal Absorption V &ues estimated based on Unknown Models have not been
Rates models v&idated for cheanws of
concern at Site F.
I
Measured Cheanw Estimated V&ues accurately Overestimates Measurement imprecision
Concentrations in represent true concentration will result in larger upper
Water and Soil confidence limit
concentrations.
Defining Soil Applied sample results for Overestimate High surface
Concentrations surface samples collected in the concentrations of site
Appropriate for RME O.l-acre overflow ditch contAminants are linUted
Conditions to a small area of the
overflow ditch. Exposure
wculations based only on
samples collected from
this area likely
overestimates the
reasonable scenario.
Air Concentrations Modeled using numerous Overestimates Field verification
assumptions demonstrates estimated
concentrations are lOx
larger than actual.
Conservative estimates of
wind threshold, grain
size, vegetative cover,
and eanssion area size,
&1 cause inflated
estimates of dust
eanssion.
-------
Table 14 - Continued
Hart Crowser
1-3947-03
Sheet 2 of 3
Area of Uncertainty Assumption Made Likely Effect Rationale
on Site Risk
Derivation of Toxicity Extrapolated from genetically Unknown Toxicity values can
Values similar populations exposed to change as more
high chemical concentrations to experimental data become
a diverse human population available.
exposed to low chemical
concentrations, sometimes using
limited experimental data.
Chromium Speciation All identified chromium is the Slightly Most environmental
more toxic chromium (VI) Overestimated chromium is chromium
(VI). Chromium does
not contribute
significantly to risks at
Site F.
Toxicity Values for Risk occurs at 500 to1,OOO Unknown - Additional risk from lead
Lead mglkg soil exposure may exist;
however, lead
concentrations are far
below 500 to 1,000
uglkg.
Toxicity Factors for Toxicity values based on limited Overestimated Based on limited available
2,4,6-DNT, 2,4-DNT, studies, toxicity from dermal data, conservative
2,6-DNT, 1,3,S-TNB exposures have not been methods were used to
evaluated, 2,4-DNT toxicity is determine toxicity factors
based on the more toxic 2,6- for most of the ordnance
DNT chemicals. Risk from
2,4,6-DNT, 2,4-DNT,
2,6-DNT, l,3,5-TNB
contributes strongly to
total site risk.
Carcinogenic Toxicity The supporting study was of Overestimated Supporting study had a
Factor for RDX sufficient quality to establish a poor control group and
slope factor counted both benign and
malignant tumors. Risk
from RDX contributes
significantly to total site
risk.
Dermal vs. Oral No difference in toxicity when Unknown Insufficient knowledge
Exposures exposed dermally versus orally concerning the
mechanisms of dermal
absorption to ordnance
chemicals
-------
able 14 - Continued
Hart Crowser
1-3947-03
Sheet 3 of 3
.
Area of Uncertainty Assmnption Made Likely Effect Rationale
on Site Risk
Model for Estimating Linear Dose-response Unknown Insufficient scientific
Cancer Risk relationship at low doses knowledge regarding
mechanisms of toxicity at
low doses.
Risks from Multiple Risks are additive Unknown Insufficient knowledge of
Chemical Exposures chemical interactions.
Exposure Constant for 30 years Overestimates Natural chemical
Concentration degradations and
dispersion will reduce
chemical concentrations
over time.
l8iiio.14
.
-------
Hart Crowser
1-3947-03
Table 15 - SUIIUD&I)' of Cleanup Levels for Site F
Soil Cleanup Level in mglkg Surface Water Cleanup Level in ugIL
Groundwater
Chemical of Direct Groundwater Cleanup Level Protection of
Concern ontac:t Protcction(a Protcction(b) in ugIL(c) Aquatic Lifc(d) Drinking Watcr(e)
2,4,6-TNT 33 0.3 2.9 40 2.9
RDX 9.1 1. 0.8 260 0.8
2,4- " 2,6-DNT 1.5 0.5. 0.13 300 0.13
1,3,5-TNB 4.0 0.25. 0.8 80 0.8
1,3-DNB 8.0 0.25. 1.6 No Data 1.6
Nitratc-N 29,000 1,000 10,000 10,000 10,000
Nitrite-N 8,000 100 1,000 No Data 1,000
Manganese 940 940 50 No Data 50
(a) MTCA Method B soil cleanup levels with the exception of manganese which is based on background data
(refer to Site F RIlFS).
(b) Groundwater Protcc:tion soil cleanup levels developed based on data from sitc-spccific leaching studies and
and conservative site condition assumptions, with the exception of manganese which is based on background data.
Cleanup levels adjusted for current Practical Quantitation Limits (PQLs) established for.
EPA Method 8330 (HPLC) are denoted with an asterik (.).
(c) MTCA Metohd B groundwater cleanup levels, with the exceptions of nitrate and nitrite (MCLS) and
manganese (SMCL).
(d) Values for TNT, RDX, DNT, TNB, and DNB obtained from literature sources (refer to Table 7-11 in Site F RlIFS
for references). Value for nitrate based on MCL.
394703\TlblelS.wtl
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~ner6liz.ed .Regional Map
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J-3947-D3 9/94
-------
rte F Historical Features Map
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Segregation
Plant(6035)
TRIGGER AVENUE
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J-3947-03 9/94
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Monitoring
I
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Cross Seclion Locolion
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Aquifer, elCcept r -MW47 which I, comp
in the Sea level AquUer.
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J-3947-o3 9/94
FIgure 3
-------
SUBASE, Bangor Map Showing Extent of Site F Groundwater
Contamination and Regional Cross Section Location
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Figure 4
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Regional Cross Section
Location and Designation
Seep Sample Location
Approximate Scale in Feet
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I I
SWFPAC
Well Number
Well Location
Screened Interval
logiC units are oall8d upon
Note: Contacts between geo wells and represents our
Interpolation be~n rlace conditions based on
interpretation 01 su su
currently available dala
Horizontal Scale In Feet
o 2000
. 100
~ertical Scale In F~el 20
Verllcal Exaggeration x
4000
.
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-------
Shallow Aquifer Water Table Elevation
+
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.
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Location and Number
Spot Water Table
Elevalion in feet
Water Table Elevation
Contour in feet
(Contour Interval = 1.0 foot)
..
Generalized Groundwater
flow Direction
N-
500
1000
BB
~
J-3947-o3 9/94
Figure 6
-------
Vertical Distribution of TNT In Soil
Former Wsstewster Lsgoon snd Overflow Ditch (Norlh"-South Profile)
'B
Soulh
I Overflow Ditch Paved Area
320 = ~ ~ ~ ~iii - ~ ~ ~ ~ ~~
~ 9
i iii = tn!! n! &
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011sel Dlslance and Direction In Feet
Exploration locallon and Number
Water level
TNT Concenlralion In mg/kg
" Not Detected
Vashon Tin (Slrallfied Drill)
Vashon AdVance Outwash 2
TNT Concentration Conlour In mg/kg
Not.: I. ConIacIJ be_SOil Unit. are - .-. interpolation be- borinOI
and represent OUt interpretation ot aWsurtace conditIOns bU8d on currently
available data.
2. 0-- Section ...,.tlon "'-" on Figure 3
Horizonlal Scale in Feet
o 00
o 10
Vertical Scale in Feet
Vertical Exaggeralion x 8
160
.
20
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HIJRTCROWSER
J-39" 7-0" 9/9"
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Extent of RDX and TNT In Shallow Aquifer
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J-3947-o3 9/94
Figure 8
-------
"laseline Exposure Pathways
rypothetical On-Site Conditions
Prevailing Wind Direction
..
.
Exposure Point
,(,nhalation E>',.,' ,l ...,-.
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. . Hart Crowser
'. . J-3947-03 .
,
. . ATTACHMENT A .
. .
.RESPONSIVENESS SUMMARY
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J-3947-03
.
ATTACHMENT A
RESPONSIVENESS SUMMARY
t
OVERVIEW
Site F is one of several operable units at SUBASE, Bangor, which was
listed on the National Priorities List (NPL) of Hazardous Waste Sites on
. August 30, 1990. SUBASE, Bangor is located in Kitsap County, on Hood
Canal approximately 10 miles north of Bremerton, Washington. Site F is
located in the southcentral portion of SUBASE, Bangor, approximately 1.5
miles east of Hood Canal.
The site received wastewaters from the demilitarization of ordnance items
containing explosives. Wastewaters were discharged into an unlined
lagoon and subsequently seeped into the soils and underlying groundwater.
A Remedial Investigation and Feasibility Study (RIIFS) for Site F was
completed on November 12, 1993. An Interim Remedial Action is under
construction at the site to reduce the movement of contaminated
groundwater from the former wastewater disposal area.
This Responsiveness Snmm~ry addresses public comments on the
Proposed Plan for Final Remedial Action at Site F. These public
comments were raised during the public comment period of January 23 to
February 22, 1994, and at the Public Meeting held on February 3, 1994, at
the Central Kitsap Junior High School, in Silverdale, Washington.
SUMMARY OF PUBLIC COMMENTS
A total of 24 comments were received by the Navy concerning the
Proposed Plan. Twelve written comments submitted in a letter during the
comment period were also discussed at the Public Meeting. Eleven
questions and comments were provided verbally by four people at the
public meeting. One additional comment letter was submitted to the Navy
during the comment period outside of the public meeting. In general,
comments received were supportive of the preferred alternative. Many of
the written submittals raised concerns or questions on more than one issue.
Some of the comments pertain to similar issues and questions about the
Proposed Plan and the contamination at Site F. Comments regarding
similar concerns and questions were grouped accordingly and addressed in
this responsiveness summary by topic areas.
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J-3947-03
Copies of the transcripts for the meeting are available at all the public
repositories listed in the Community Relations section of the Record of
Decision and a copy is part of the Adm;n;strative Record. Copies of the
letters received have been included in the Administrative Record.
RESPONSE TO COMMENTS
The comments were grouped into nine topics which address the issues
raised at the public meeting and during the public comment period. Each
of these topics is discussed separately below.
1. Shallow Aquifer Characterization and Potential Impacts to Seeps
and Off-Base Water Supplies
The following concerns were raised in the public comments:
(a)
(b)'
(c)
Response:
Potential interconnection of the Shallow Aquifer on base with
off-base, shallow zones of groundwater which are used for
domestic water supply at some locations;
Potential future impacts to the seeps and downstream surface
water, which is used by off-base residents of Old Bangor for
various (non-drinking water) uses. One or more questions were
also raised regarding what monitoring of the seeps had been and
will be conducted, and the time estimated for ordnance
compounds to reach the seeps; and
What is the cause of long-term water level decline in the
Shallow Aquifer?
Each of these comments is addressed individually below.
(a)
The Navy concurs that there is uncertainty regarding the
possibility that the Shallow Aquifer is connected with shallow
groundwater zones off base which are locally used for water
supply. However, whether the Shallow Aquifer at Site F is
interconnected with shallow groundwater off base or not does
not change the Navy's commitment to addressing contam;nation
in the Shallow Aquifer at Site F, nor does it change its selected
alternative for doing so. The objective of the selected
alternative is to restore the Shallow Aquifer to drinking water
standards. The enhanced groundwater treatment system will be
4
4.
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.
)
(b)
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J-3947-03
operated and modified as appropriate to achieve the established
cleanup levels, to the extent practicable, and provide long-term
protection of human health and the environment.
The variety of available geologic and hydrologic information
provided in the RIfFS supports the hypothesis that the Shallow
Aquifer present at Site F (thick sequence of advance outwash
sand) does not extend off base in the direction that groundwater
from Site F is moving (in the vicinity of Old Bangor). The
Navy agrees that it is possible that groundwater discharge from
the Shallow Aquifer via seeps may provide recharge to shallow
groundwater zones west of the base boundary which, based on
review of well logs from the area, appear to be within sand
zones within glacial till.
As discussed in the response to (a) above, the objective of the
selected alternative is to restore the Shallow Aquifer to drinking
water standards. This objective includes preventing further
migration of the groundwater contamination into uncontaminated
portions of the aquifer, which is the sole objective of the Site F
interim remedial action (IRA). By preventing migration of the
groundwater contamination, the seeps will be protected. The
Navy is confident that the groundwater remediation will be
effective in protecting the seeps in the long-term, and thus
protect users of surface water originating at the seeps.
As discussed in the public meeting, locations where the seep
. discharge is diverted across the base boundary into Old Bangor
were sampled as part of the RIIFS in 1991. Subsequent
sampling at monitoring wells closer to the zone of groundwater
contamination confIrm that the groundwater contamination is
currently at. least a mile from the seeps. Groundwater sampling
. of on-base compliance monitoring wells, positioned outside the
zone of contamination, will be an integral part of the
groundwater remediation program to track the zone of
contamination.
The RIfFS presents a time range of 10 to 30 years for the most
mobile groundwater constituents from Site F to reach the seeps.
Ten years represents a reasonable maximum exposure (RME)
estimate which was derived for the purposes of the risk
assessment using highly conservative values for each physical
and chemical transport parameter (e.g., maximizing flow
velocities and minimizing contaminant retardation). Thirty
years represents an average value which, based on physical and
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J-3947-03
geochemical site conditions, is considered a more probable
outcome. Consequently, 30 years was presented in the
Proposed Plan.
(c)
The reason for the water level declines measured between the
mid-1970s and early 1990s is uncertain, and is likely a
combination of effects including long-term regional drought.
However, the Navy is confident that the decline is not due to
improperly decommissioned old monitoring wells extending to
the Sea Level Aquifer, or overpumping of the Shallow Aquifer
at SUBASE. It should also be noted that water levels in the
Shallow Aquifer were generally stable (disregarding seasonal
fluctuations) over the two-year period of RIfFS monitoring
(1990 to 1992).
(
A thorough review of the information on the old (before 1976)
monitoring wells installed at Site F indicates that all these wells
were installed in the Shallow Aquifer; none of them extended to
the Sea Level Aquifer. A technical memorandum is available in
the Administrative Record which documents information on
these old (pre-1976) wells, and their completion in the Shallow
Aquifer. There are existing deep monitoring wells in the
. general vicinity of Site F which were installed in the late-1970s
by the Navy to monitor recharge of groundwater associated with
dewatering during consttuction of the Delta Pier. Well
consttuction data for these wells indicate the use of grout seals
during. installation. The grout seals prevent movement of water
within the borehole, therefore these wells also should not
provide a conduit for flow between aquifers.
There are no water supply wells in the Shallow Aquifer at
SUBASE, Bangor. Although there are domestic wells in the
. Shallow Aquifer off base to the east of Site F, the combined
yield of these wells is insufficient to effect a uniform 11-foot
water level drop in the transmissive regional aquifer.
Because the water level drop was uniform in monitoring wells
located almost 3,000 feet apart, cessation of.discharge at the
wastewater lagoon at Site F also doesn't account for this
magnitude drop in water level since, during active discharge, 11
feet of groundwater mounding would not have extended
uniformly 3,000 feet from the lagoon.
4
Data collected from Sea Level Aquifer well TH-llS during the
RIfFS indicate groundwater levels in the Sea Level Aquifer in
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J-3947-03
the Site F vicinity have also dropped 8 to 12 feet between 1977
(well installation) and 1991. Possible long-term regional
drought may account for the observed decline in both the
Shallow and Sea Level Aquifer water levels.
)
2. Potential Impacts to Sea Level Aquifer
Summary of Questions:
One question from the public related to monitoring of the Sea Level
Aquifer.
Response:
The Sea Level Aquifer is the first aquifer beneath the Shallow Aquifer.
A downward hydraulic gradient exists between the two aquifers,
therefore groundwater flows from the Shallow Aquifer toward the Sea
Level Aquifer. The two aquifers are separated by a 60- to 80- foot
thick, low-permeability aquitard (roughly 100,000 times less permeable
than the aquifers), which greatly restricts the rate of groundwater flow
between aquifers. Furthermore, the fine-grained clayey silt and higher
percentages of organic matter comprising the aquitard will cause
substantial adsorption of organic chemicals (like ordnance). Because of
the very low rate of groundwater flow through the aquitard and the
substantial adsorption of contaminants expected to occur within the
aquitard, negligible ordnarice concentrations would be expected to reach
the Sea Level Aquifer.
The SWFPAC (Strategic Weapons Facility Pacific) well, screened
solely in the Sea Level Aquifer, was sampled as part of the RIfFS
sampling program. This well is located about a mile northwest of the
former wastewater lagoon at Site F. It is important to note that the
groundwater contamination from Site F doesn't reach the bottom of the
Shallow Aquifer until it has migrated more than 1,000 feet from the
former lagoon. Although a compliance monitoring plan for the
groundwater remediation program has yet to be developed, it will
include periodic monitoring of the SWFP AC well for ordnance to
provide early warning of any constituent migration into the Sea Level
Aquifer.
.
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3. Site F Interim Remedial Action Compliance Monitoring
.
Summary of Questions:
Questions were raised by the public regarding compliance monitoring
criteria for the Site F interim remedial action (IRA), and the time for
hydraulic containment of the groundwater cont~mination to be achieved
once the IRA extraction and reintroduction wells were operational.
(
Response:
Compliance with the cleanup objectives will be evaluated by measuring
groundwater constituent concentrations in the Shallow Aquifer as the
remediation progresses. The cleanup levels (as listed in the Proposed
Plan and in this Record of Decision) are the criteria that will used to
evaluate compliance with the cleanup objectives.
Hydraulic containment will be determined using both groundwater
quality data from wells located downgradient of the current extent of
groundwater contamination, and from water level data collected in the
vicinity of the extraction wells. Once operational, the groundwater
extraction and reintroduction system should achieve containment
relatively quickly (perhaps within several weeks of operation depending
on required adjustments). Adjustments of the extraction/reintroduction
system (e.g., adjusting individual extraction well pumping rates) may
be necessary in the fIrst few weeks of operation of the extraction and
reintroduction systems.
4. Groundwater Remediation Plan for the Selected Alternative
Summary of Questions:
Questions were received from the public regarding:
(a)
How the RIfFS groundwater alternatives correspond to the
preferred alternative for groundwater remediation;
(b)
Performance and cost of UV fOzone for groundwater treatment;
and
(c)
The locations of the reintroduction wells.
.
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J-3947-03
;
Response:
(a)
)
(b)
.
The selected alternative for groundwater remediation
corresponds to groundwater Alternatives 7 or 8 in the Site F
Feasibility Study. The only difference between groundwater
Alternatives 7 and 8 in the FS was the duration of operation (10
and 30 years, respectively). The duration of operation of the
selected alternative groundwater system will be based on
performance and compliance with cleanup standards rather than
a specific time frame. Consequently, the duration of operation
was not specified in the Proposed Plan, and is not specified in
this ROD. System design and optimization will largely defme
the expected period of operation; however, it is uncertain how
well the actual extraction system performance will compare with
the groundwater modeling results.
Analytical results obtained during the field test (phase ill)
portion of the UV /Oxidation Treatability Study indicate that
UV /Ozone treatment can effectively achieve cleanup levels for
ordnance compounds detected in Site F groundwater, including
DNT.
The estimated costs of UV /Ozone treatment provided on Figure
6 of the Proposed Plan include $40,000 per year for operation
and labor cost for system maintenance. The basis of this cost
estima~ (influenced largely by expected influent ordnance
concentrations in the extracted groundwater) are significantly
different than the assumptions used to develop the cost estimate
presented in the June 18, 1993, TRC meeting. The fact that the
two estimates yielded nearly identical overall costs is purely
coincidental.
(c)
As stated in the public meeting, the reintroduction wells for the
Site F IRA are located adjacent to SWFP AC support, which is
downgradient of the leading edge of the groundwater
cont:tmination in the Shallow Aquifer. The locations of
potential additional reintroduction wells for the enhanced
groundwater treatment alternative will be decided during the
design phase.
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5. Soil Remediation Plan for the Selected Alternative
.
Snmm;lry of Questions:
Some questions raised during the public meeting addressed the
biological treatment process, specifically, time frame, ingredients, and
treatment byproducts; potential dust generation; and what will be done
with the treated soil. In addition, a comment addressed the infiltration
barrier and potential additional soil treatment in the future.
(
Response:
As discussed in the public meeting, on-site biological treatment of Site
F soils should be completed within one year of the time of its
implementation. However, this does not include the time period
associated with design, construction, and system startup. Amendment
added to contaminated soil during the biological treatment process will
include organic materials (e.g., potato waste, manure, sawdust) which
provide nutrients to the microorganisms. Results from treatability
studies have demonstrated that the ordnance compounds are broken
down into less complex, less toxic compounds. The studies indicate the
treated soils meet direct contact soil cleanup levels for all ordnance
compounds and their degradation products. During treatment, dust
generation will be controlled by adding water, which is used as a
normal part of the treatment process. Once tteatment is complete, the
treated soils will likely be used to regrade the excavation and overflow
ditch at Site F prior to installation of the infiltration barrier.
The infiltration barrier will greatly limit migration of constituents from
soils into the Shallow Aquifer. The infiltration barrier will be
specifically designed to reduce infiltration of precipitation and thereby
prevent further leaching of residual ordnance constituents to the
Shallow Aquifer.
6. Laboratory Analysis of Ordnance Compounds - Practical
Quantitation Limits
Summary of Questions:
One public comment addressed the adequacy of current analytical
methods in quantitating ordnance concentrations down to the cleanup
levels.
.
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1-3947-03
Response:
.
)
The Navy recognizes past limitations in quantitating ordnance
compounds, particularly RDX, in soil and groundwater. However,
current analytical methods provide practical quantitation limits (PQLs)
below cleanup levels, with the exception of DNT and RDX soil cleanup
levels for protection of groundwater, as stated in the Proposed Plan.
However, because the groundwater protection soil cleanup levels were
estimated using conservative assumptions, and the volume of soils at
Site F with concentrations between the estimated cleanup level and the
PQL is likely to be small, soils with RDX or DNT concentrations at or
below PQLs (1 mglkg RDX and 0.5 mglkg DNT) should not pose a
risk to groundwater. Furthermore, the infiltration barrier will extend
beyond the zone of coutaminated soils, thus providing a measure of
safety for the soils potentially containing ordnance concentrations below
PQLs but above estimated groundwater protection cleanup levels.
7. Potential Impact of Site Contamination on Proposed RV Center and
Golf Course
Summary of Questions:
One question raised during the public meeting concerned the proximity
of soil cont~rnination at Site F to a proposed RV Center and golf course
driving range at SUBASE, Bangor.
Response:
As discussed in the public meeting on the Site F proposed plan, the
proposed RV Center and driving range are approximately 3,300 feet
from Site F, and are well outside the zone of soil CODtamination at Site
F.
8. Process for Removing a Site from the National Priorities List
Summary of Questions:
One question raised during the public meeting regarded the process for
removing Site F from the National Priorities List.
Response:
a
According to the National Contingency Plan (40 CFR 300.425(e)),
EP A, in consultation with the State of Washington, could delete
SUBASE, Bangor from the National Priorities List (NPL) after
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J-3947-03
determining that the Navy has implemented all appropriate actions.
Individual operable units (e.g., Site F is operable unit 2) are not
eligible for delisting; only the NPL Site (SUBASE, Bangor) in its
entirety could be delisted. The State of Washington must concur with
the delisting. As part of the delisting process, the public would be
made aware of EPA's intent to delist SUBASE, Bangor by publishing
notices in local newspapers and posting a notice in the Federal
Register.
4
9. Rationale for Choosing the Selected Alternative
Summary of Questions:
Two general comments were received regarding the overall decision to
take action at Site F. One comment received during the public meeting
expressed approval for the selected alternative. One comment letter
received during the comment period stated that, rather than undertaking
active remediation at Site F, monitoring of off-site wells should
continue with the Navy supplying water to these residents in the future
if their wells ever become contaminated.
Response:
The Navy is committed to . implementing permanent solutions to the
extent possible, which provide long-term protection of human health
and the environment. The No Action alternative could in the future,
based on the results of the RIIFS, result in risk to humans or aquatic
life e~ountering contaminated soil or groundwater (seeps) at Site F.
It is the intent of the Navy in this proposed action to be proactive in
addressing this contamination to avoid future potential impact.
Furthermore, the Navy is required, under the terms of a Federal
Facility Agreement, to comply with applicable environmental
regulations. Because the existing contamination represents a potential
risk (as determined using EPA's standard risk assessment),
environmental regulations require cleanup be undertaken unless it can
be demonstrated it is inordinately costly to do so.
The Navy feels the selected remedy provides a cost-effective program for
reducing site risk. In general, the public who have commented on the
proposed cleanup have been supportive.
sildrod.fm\appa
.
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