PB97-964502
EPA/541/R-97/032
November 1997
EPA Superfund
Record of Decision:
Schofield Barracks (US Army),
Operable Unit 2,
Oahu, HI
2/7/1997
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U.S. Army
Environmental
Center
Final Record of Decision
for Operable Unit 2
Schofield Army Barracks
Island of Oahu, Hawaii
Prepared by:
Harding Lawson Associates
707 Seventeenth Street, Suite 2400
Denver, Colorado 80202
235 Pearlridge Center Phase
98-1005 Moanalua Road
Aiea, Hawaii 96701
August 12,1996
Prepared for:
U. S. Army Environmental Center
Aberdeen Proving Ground, MD 21010-5401
Contract No. DAAA15-91-D-0013
Delivery Order DA03
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DEPARTMENT OF THE ARMY
HEADQUARTERS. UNITED STATES ARMY GARRISON. HAWAII
SCHORELD BARRACKS. HAWAII 96857-5000
REPLY TO
ATOaioNOF 2 5 SEP 1996
Directorate of Public Works
Mr. Mark Ripperda
Remedial Project Manager, H-9-4
U.S. Environmental Protection Agency
Region IX
75 Hawthorne Street
San Francisco, California 94105-3901
Dear Mr. Ripperda:
The Final Record of Decision for Operable Unit 2 is hereby transmitted to you. The Army has
approved this document and requests U.S. Environmental Protection Agency concurrence by signing on
sheet 1-5 of said document. Another copy of this document has been sent to the Department of Health,
State of Hawaii for their concurrence. Upon concurrence, request that the original signature sheet be
transmitted to the Army for reproduction and distribution of the completed document. The original
signature sheets will be sent back to your office upon completion of that function.
If you have any questions, please contact Mr. Jon Fukuda, Environmental Division, (808) 656-6790,
or Mr. James Daniel, U.S. Army Environmental Center, (410) 671-1501.
Sincerely,
ennis J. Fontana
Colonel, U.S. Army
Director of Public Works
Enclosure
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Final Record off Decision
for Operable Unit 2
Schofield Army Barracks
Island off Oahu, Hawaii
Prepared for
U.S. Army Environmental Center
Installation Restoration Division
HLA Project No. 33537 07.04.00
Contract DACA31-94-D0069
Delivery Order No. 0004
August 12, 1996
Harding Lawson Associates
Engineering and Environmental Services
707 Seventeenth Street Suite 2400
Denver, CO 80202 - (303) 292-5365
Recycled Paper
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Environmental Services Program Support
Final Record of Decision for Operable Unit 2
Schofield Army Barracks, Island of Oahu..Hawaii
August 12, 1996
Contract Number DACA31-94-D0069
Delivery Order No. 0004
Report Preparation Team:
Catherine Armstead
Laura Hollingsworth
Neil Myers
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CONTENTS
1.0 DECLARATION 1-1
1.1 Site Name and Location .-. 1-1
1.2 Statement of Basis and Purpose 1-1
1.3 Assessment of the Site 1-2
1.4 Description of the Selected Remedy 1-2
1.5 Declaration Statement 1-2
2.0 DECISION SUMMARY 2-1
2.1 Schofield Barracks Site Location and Description 2-1
2.2 Schofield Barracks Installation Operational History 2-2
2.3 Enforcement and Regulatory History 2-3
2.4 Operable Unit 2 Site Selection History 2-4
2.5 Operable Unit 2 Site Description 2-5
2.6 Highlights of Community Participation 2-5
2.7 Scope and Role of Operable Unit 2-7
2.8 Site Characterization 2-8
2.8.1 Nature and Extent of Contamination 2-8
2.8.2 Contaminant Fate and Transport 2-9
2.9 Summary of Site Risks 2-10
2.10 Description of Alternatives 2-13
2.10.1 Alternative 1 - No Action/Institutional Controls 2-16
2.10.2 Alternative 2 - Air Stripping 2-16
2.10.3 Alternative 4 - Ozone/Hydrogen Peroxide Treatment 2-18
2.11 Summary of Comparative Analysis of Alternatives 2-19
2.11.1 Overall Protection of Human Health and the Environment 2-20
2.11.2 Compliance with ARARs 2-20
2.11.2.1 High Groundwater Volume 2-21
2.11.2.2 Potential Impacts to Basal Aquifers 2-21
2.11.2.3 Protectiveness of Wellhead Treatment 2-22
2.11.3 Long-term Effectiveness and Permanence 2-22
2.11.4 Reduction in Toxicity, Mobility, and Volume 2-22
2.11.5 Short-term Effectiveness 2-23
2.11.6 Implementability 2-23
2.11.7 Cost 2-23
2.11.8 State Acceptance 2-23
2.11.9 Community Acceptance 2-24
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2.12 Selected Remedy 2-24
2.13 Statutory Determinations 2-25
3.0 RESPONSIVENESS SUMMARY 3-1
3.1 Overview 3-1
3.2 Background on Community Involvement 3-1
3.3 Summary of Comments Received During Public Comment Period and Department
of the Army Responses 3-2
4.0 ACRONYMS 4-1
5.0 REFERENCES 5-1
TABLES
2.1 Summary of Noncarcinogenic and Carcinogenic Risks for OU 2
2.2 Location-specific Applicable or Relevant and Appropriate Requirements for Schofield Barracks
OU2
2.3 Chemical-specific Applicable or Relevant and Appropriate Requirements and
To-Be-Considered" Guidance for Cleanup of Groundwater at Schofield Barracks OU 2
2.4 Action-specific Applicable or Relevant and Appropriate Requirements for OU 2 at, Schofield
Army Barracks, Hawaii
2.5 Preliminary Estimated Influent Chemicals of Concern Concentrations and Proposed Treatment
Standards for Schofield Army Barracks OU 2
2.6 Summary of Comparative Analysis of Alternatives
2.7 Calculations for Estimated Maximum Trichloroethene and Carbon Tetrachloride Vapor
Discharge from Alternative 2 (Air Stripping Treatment)
2.8 Summary of Estimated Costs for Remedial Action Alternatives at Schofield Army Barracks for
OU2
2.9 Estimated Cost Summary of Selected Remedy - Air Stripping
FIGURES
l.l Location Map of Schofield Barracks
1.2 Site Map of Schofield Barracks
2.1 Regional Groundwater Systems of Oahu, Hawaii
2.2 Regional Hydrogeologic Cross Sections A-A' and B-B'
2.3 Trichloroethene Isoconcentration Map
2.4 Proposed Long-term Groundwater Monitoring Network
2.5 Alternative 2 Process Flow Diagram of Air Stripping OU 2 Groundwater Treatment
2.6 Alternative 4 Process Flow Diagram of Ozone/Hydrogen Peroxide Oxidation System for OU 2
Groundwater Treatment
APPENDIXES
A SYNOPSIS OF COMMUNITY RELATIONS ACTIVITIES
B COMMENTS RECEIVED DURING PUBLIC COMMENT PERIOD AND ARMY RESPONSES
C ANALYSIS OF THE IMPACT OF TRICHLOROETHENE ON CARBON USAGE
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Declaration
1.0 DECLARATION
This Final Record of Decision (ROD) for Operable Unit (OU) 2 has been prepared by Harding
Lawson Associates (HLA) for the U.S. Army Environmental Center (USAEC) under Delivery
Order No. 0004 of the Total Environmental Services Program Support (ESPS) Contract
DACA31-94-D-0069. This report documents the remedial action plan for OU 2 at Schofield
Army Barracks (Schofield Barracks), Island of Oahu, Hawaii.
1.1 Site Name and Location
Schofield Barracks is located in the north-central plateau of the Island of Oahu in the State of Hawaii
(Figure 1.1). The Schofield Barracks installation is approximately 22 miles northwest of the City of
Honolulu. The closest municipality is Wahiawa, which is immediately north of Schofield Barracks.
The installation is divided into two sections, the East Range and the Main Post (Figure 1.2),
encompassing a total area of approximately 27.7 square miles. Wheeler Army Airfield (Wheeler) lies
between and to the south of the two Schofield Barracks sections.
Operable Unit 2 addresses the contaminated groundwater system beneath Schofield Barracks.
1.2 Statement of Basis and Purpose
This decision document (ROD) presents a response action for OU 2, the contaminated groundwater
system beneath Schofield Barracks. This action was selected in accordance with the Comprehensive
Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), as amended by the
Superfund Amendments and Reauthorization Act of 1986 (SARA) and, to the extent practicable, the
National Oil and Hazardous Substances Pollution Contingency Plan (NCP). This ROD explains the
basis for selecting the response action for OU 2. Information supporting the selected response action is
contained in the Administrative Record for Schofield Barracks.
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Declaration
1.3 Assessment of the Site
Actual or threatened releases of hazardous substances from this site/ if not addressed by implementing
the response action selected in this ROD, may present a current or potential threat to public health,
welfare, or the environment.
1.4 Description off the Selected Remedy
The function of OU 2 is to address base-wide groundwater contamination. The selected remedy
provides protection of human health and the environment by reducing potential risks associated with
domestic use of the contaminated groundwater. The remedy includes the following components:
• Continued treatment for contaminants of concern (COCs) present in extracted groundwater at
the Schofield Barracks Supply Wells by air stripping at the wellhead followed by discharge of
the treated water to the distribution system
• The Army must consult with EPA and the State of Hawaii prior to abandoning the Schofield
Barracks water supply wells, because production at these wells may help to control plume
migration
• Long-term sampling and analysis of water supply wells, agricultural wells, and monitoring
wells in the region
• Implementation of the contingency of wellhead treatment on any water supply wells that are
impacted by the plume from Schofield Barracks above one-half of the Maximum Contaminant
Level (MCL) as established under the Safe Drinking Water Act (SDWA)
• Upgrade the treatment system or pay any incremental costs for treatment caused by
contamination from Schofield Barracks at wells that already have a treatment system in place
• Conduct five-year site reviews with the State of Hawaii Department of Health (DOH) and the
U.S. Environmental Protection Agency (EPA).
The details of the monitoring plan, evaluation process for implementation of wellhead treatment, and
description of conditions at existing water wells may be found in the Final Operation and Maintenance
and Long-Term Groundwater Monitoring Plan for Operable Unit 2, Schofield Army Barracks, which is an
addendum to this ROD. The EPA and DOH concur with the above selected response actions (remedy).
1.5 Declaration Statement
The selected remedy is protective of human health and the environment, and is cost effective, but does
not meet the applicable or relevant and appropriate requirement (ARAR) for restoration of groundwater
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Declaration
to MCLs under the SDWA. An ARAR waiver for technical impracticability (TI waiver) is being invoked
for this ROD, as described in the Justification for Technical Impracticability Waiver at Schofield Barracks
for the Ground Water Record of Decision. The TI waiver justification is part of the Administrative
Record for Schofield Barracks.
The selected remedy complies with CERCLA in that this action is a permanent solution to the
maximum extent practicable or necessary for OU 2 and satisfies the NCP preference for treatment as a
principal element of the remedy. A TI waiver is necessary for this action, however, because
contaminants will remain in the groundwater at levels of concern for an undetermined period of time.
Therefore, a groundwater monitoring program will be implemented to assess changing aquifer
conditions and to track potential movement of the TCE/carbon tetrachloride plumes. A site review will
be conducted once every five years until groundwater remediation goals, which are the SDWA MCLs,
are achieved in the groundwater system.
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Declaration
Frank L. Miller, Jr.
Major General, U.S A.
Assistant Chief of Staff for Installation Management
U.S. Army
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Declaration
Dan Opalski~ f ~ .
Chief, Federal Facilities Cleanup Branch
EPA, Region 9
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Declaration
Lawrence Mike, M.D.
Director of Health
State of Hawaii
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Peart
Harbor
Honolulu
Explanation
Scfwftetd Barracks
Cities, towns
Rwers, streams
Higtiways, roads
Sources: US. Army Pacific Environmental Heatti
Engineering Agency (USAPEHEA). 1977.
642d Engr.eer Battalion (TOPO). 1977.
ESc. 1384.
Seate
5
10
Mies
10
Kaometers
Harding Lawson Associates
Engmaonng and
Prepared for
U.S. Army Environmental Center
Aberdeen Proving Ground. Van/land
Schofield Barracks. Island of Oahu. Hawaii
Figure 1.1
Location Wap of Schcfieid Barracks
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Explanation
Wt**** Ainty Avfiild tnundvy
(icgas±
"^
Piepated lot:
U.S. Aimy Envlfonmental Cental
AMidMn Prooing Oiound. M«iyKnd
Schofield Aimy Ban»c*». Island ol Oahu, Hawaii
Flgw* 1.2
Site Map ol ScnofieM Bairacka
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2.0 DECISION SUMMARY
This section provides an overview of the site-specific factors and analyses that led to final remedy
selection. This overview includes a general site description, site history, enforcement and regulatory
history, highlights of community participation, scope and role of OU 2, site characteristics, summary of
site risks, and documentation of significant changes to these elements. Much of the information
presented in this section was derived from previous investigations performed by the U.S. Department of
the Army (Army) and its contractors and has been previously presented in more detail in the
Preliminary Assessment/Site Investigation (PA/SI) Report (HLA, 1992a), Final Work Plan for Schofield
Army Barracks Remedial Investigation/Feasibility Study (RI/FS) (HLA, 1992b), the Final OU 2 Phase I
and Phase n Sampling and Analysis Plans (SAPs) (HLA, 1993 and I995c), the Final OU 2 RI Report
(HLA, 1996a), and the Draft Feasibility Study for Operable Unit 2 (HLA, 1996b).
2.1 Schofield Barracks Site Location and Description
Schofield Barracks is located in central Oahu (Figure 1.1) within the physiographic province known as
the Schofield Plateau. Ground surface elevations range from approximately 700 feet (National Geodetic
Vertical Datum of 1929 [NGVD]) near the central portion of Schofield Barracks to approximately
4,000 feet (NGVD) near the western boundary of the Main Post in the Waianae Mountain Range. The
drainage divide of the Schofield Plateau runs roughly east-west through the center of the Main Post.
North of this divide, watercourses flow to the north and discharge into Kaiaka Bay at the town of
Haleiwa. South of this divide, watercourses flow south and discharge into the West Loch of Pearl
Harbor. Narrow gulches dissect the plateau where streams have eroded the land surface.
The relatively flat Schofield Plateau was formed as basaltic lava flowed from the adjacent Koolau and
Waianae volcanoes to the east and west, respectively. The upper 100 to 200 feet of the basaltic bedrock
within the Schofield Plateau is weathered saprolite. The saprolite consists of soil (primarily fine-
grained materials including silt and clay) formed by in situ decomposition of the basaltic bedrock. The
saprolite is underlain by relatively unweathered basaltic bedrock consisting of interbedded pahoehoe
and a'a lava flows. The lava flows are highly fractured with cinder and clinker zones.
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Decision Summary
Three types of groundwater systems have been identified in central Oahu: (1) the Schofield High-level
Water Body, (2) basal groundwater, and (3) dike-impounded groundwater (Figures 2.1 and 2:2). The
Schofield High-level Water Body is located beneath the Schofield Plateau, and subsequently, the site.
This water body is bound to the east and west by dike-impounded groundwater and to the north and
south by basal groundwater. Lower permeability rocks (possibly volcanic dikes and/or buried ridges)
structurally separate these groundwater systems from one another. The Schofield high-level aquifer has
a high transmissivity and hydraulic conductivity. The depth to groundwater at the site is
approximately 600 feet below ground surface (bgs) (approximately 270 feet above mean sea level [msl]).
The climate at Schofield Barracks, which is south of the Tropic of Cancer at approximately 21 degrees
north latitude, is characterized by moderate temperatures that remain relatively constant throughout the
year. The average annual rainfall in the vicinity of Schofield Barracks is approximately 1.2 meters
(Giambelluca and others, 1986), more than half of which occurs during the rainy season from November
through February. Trade winds have an average speed of 12 knots and prevail from the northeast or
east approximately 70 percent of the time.
Because of the relatively large amounts of undeveloped land, combined with a relatively large amount
of vertical relief, Schofield Barracks is host to diverse and abundant flora and fauna. Undisturbed
natural vegetation at Schofield Barracks is found primarily in the steep gulches on the east and west
sides. These gulches support birds and other fauna and blocks of forestry plantings and dense
shrubbery growth.
2.2 Schofield Barracks Installation Operational History
Schofield Barracks was established in 1908 as a base for the Army's mobile defense of Pearl Harbor and
the Island of Oahu. It served as a major support facility during World War n (WWII) temporarily
housing more than one million troops. It also served as a support and training facility during the
Korean and Vietnam conflicts. Since the Vietnam conflict, it has served primarily as a training facility.
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Decision Summary
Schofield Barracks is the Army's largest installation outside of the continental United States. It
currently serves as the home of the 25th Infantry Division (Light), whose mission is to be prepared to
respond to war at a moment's notice. Installation facilities include a medical facility, community and
housing support facilities, and transportation and repair facilities.
2.3 Enforcement and Regulatory History
TCE, a commonly used cleaning solvent, was detected in the Schofield Barracks water-supply wells in
1985. The source of the TCE contamination could not be identified. In September 1986, the Army
installed air-stripping treatment units to remove TCE from the Schofield Barracks domestic water
supply. In 1987, the EPA established an MCL for TCE of 5 micrograms per liter 0*g/l) in drinking water.
TCE has not been detected in Schofield Barracks' treated water supply at concentrations greater than
this EPA-established limit
As a result of the detection of TCE in the Schofield Barracks water-supply wells, Schofield Barracks was
placed on the National Priorities List (NPL) in August 1990. The NPL was developed by EPA to identify
sites that may present a risk to public health or the environment. Investigations conducted following
NPL listing also revealed carbon tetrachloride contamination in the groundwater beneath the Former
Schofield Barracks I-andfill; therefore, carbon tetrachloride contamination of the groundwater will be
addressed along with TCE under this ROD.
After Schofield Barracks was placed on the NPL, a Federal Facility Agreement (FFA) was negotiated
among EPA, the State of Hawaii, and the Army under CERCLA, Section 120. The FFA was signed by
the Army on September 23,1991, EPA on September 27,1991, and State of Hawaii on June 5,1996.
The FFA identified Schofield Barracks as being under the jurisdiction, custody, or control of the U.S.
Department of Defense (DOD) and subject to the Defense Environmental Restoration Program (DEEP).
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Decision Summary
Operable Untt 2 Stte Selection History
As a part of the FFA, the Army and regulatory agencies agreed to divide the program into subunits
called OUs to address potential areas of contamination at Schofield Barracks in an organized
This ROD addresses OU 2, which was established to address the contamination present in the
groundwater beneath Schofield Barracks.
During 1991, the Army began to investigate potential contaminant sources at Schofield Barracks
through implementation of a PA/SI as required by the FFA. The objective of the PA was to identify
possible onpost and offpost groundwater contamination sources both at Schofield Barracks and the
•
surrounding study area. The PA consisted of the following three activities designed to collect
additional information regarding Schofield Barracks and nearby offpost communities:
• Conduct an onpost records search of 10 onpost sites (including the Former Landfill) identified
in the FFA (EPA, State of Hawaii, and Army, 1991).
• Survey and sample existing water-supply wells in the Schofield High-level Water Body.
• Conduct an industrial activity survey of communities in the study area to identify potential
offpost TCE sources.
The objective of the SI was to collect field data to assess potential sources of contamination at the
Former Laundry, the East Range Disposal Area, and the Former Landfill.
Results of the records search, industrial activity survey, well survey, and sampling were discussed in
detail in the PA/SI Report (HLA, 1992a). Given the results of the PA/SI, additional groundwater
investigations were recommended.
The investigation of groundwater contamination (OU 2) was conducted under a two-phase program
Phase I focused on collecting data on aquifer characteristics (regional and local) to provide a better
understanding of the aquifer behavior. The specific goals of the Phase IRI are presented in the Final
SAP for OU 2 Phase I RI (HLA, 1993). The OU 2 Phase H investigation is based on results of the OU 2
Phase I investigation, the OU 1 investigation, the OU 4 Phase I investigation, and the refined site
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Decision Summary
conceptual model. The results of the OU 2 Phase I and n investigations are presented in the Final OU 2
RI Report (HLA, 1996a).
Operable Unit 2 Site Description
OU 2 consists of the groundwater beneath Schofield Barracks. This groundwater is 550 to 650 feet bgs
and is part of the groundwater body known as the Schofield High-level Water Body. It is called a "high-
level" water body because the groundwater levels beneath Schofield Barracks are much higher than
groundwater levels in the nearby coastal areas because of underground geologic structures which act as
dams to groundwater flow. Most of the groundwater beneath Schofield Barracks originates as rainfall in
the Koolau and Waianae mountain ranges to the east and west This rainfall seeps into the ground in
the mountain areas and moves through the subsurface eventually reaching Schofield Barracks. A small
amount of water also seeps into the ground in the Schofield Barracks area and reaches the underlying
groundwater. The groundwater beneath Schofield Barracks eventually flows into the coastal water
bodies to the north and south over the groundwater dams.
A source for the TCE in the groundwater beneath Schofield Barracks has not been identified; however,
it is likely that the substance migrated from a ground surface location through the soil and bedrock to
the underlying groundwater. The former landfill was identified as the source of the carbon
tetrachloride in the groundwater underlying that site. The Schofield Barracks water-supply wells are
currently extracting contaminated groundwater from the groundwater system (OU 2); however, all
contaminated water currently being pumped from the groundwater beneath Schofield Barracks is being
treated by an air-stripping treatment system, which removes the contamination to acceptable standards
before the water is distributed for human use.
2.6 Highlights of Community Participation
In an effort to involve the public, the Army has undertaken several public and community awareness
efforts including issuance of employee bulletins and post newspaper articles for Schofield Barracks
employees, media interviews, news releases, and meetings with local officials and neighborhood boards
for offpost residents. In addition, the Army has held public meetings, issued fact sheets, and
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Decision Summary
established an Army contact for the public at Schofield Barracks' Public Affairs Office. Copies of work
plans, technical reports, fact sheets, and other materials related to the project are available for public
review at the following local repositories:
Mililani Public Library
95-450 Makaimoimo Street
Mililani, Hawaii 96789
Wahiawa Public Library
820 California Avenue
Wahiawa, Hawaii 96786
U.S. Army Garrison, Hawaii
Directorate of Public Works
Building 105
Wheeler Army Airfield. Hawaii 96857-5000
State of Hawaii Department of Health
Environmental Quality Control Office
220 South King Street, 4th floor
Honolulu, Hawaii 96813
On May 24,1996, the Army presented the Proposed Plan for OU 2 at Schofield Barracks to the public
for review and comment The Proposed Plan summarizes information collected during the OU 2 PA/SI
and RI and other documents in the Administrative Record for the Schofield Barracks that are available
at the above local repositories. In addition, the proposed plan summarizes the alternatives contained in
the FS and outlines the preferred alternative. Prior to the public meeting copies of the Proposed Plan
were placed in the local repositories and a public notice was placed in the local newspapers advising
the public of its availability. Also, copies of the Proposed Plan were mailed directly to residents and
public officials on the Community Relations Plan mailing list.
Comments regarding the Proposed Plan were accepted during a 30-day public review and comment
period that began on May 24,1996. A public meeting was held on June 12,1996, at 1139A Kilani
Avenue, Wahiawa, Hawaii. At that time, the public had the opportunity to discuss the plan with the
Army, EPA, and the Hawaii Department of Health (DOH) and express concerns about the plan. In
addition, written comments were accepted during the public comment period. Responses to comments
received during the public comment period are included in the Responsiveness Summary (Section 3.0),
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which is part of this ROD. In addition, responses to the comments received during the public comment
period were sent directly to the individual commenter. The public comment period, as discussed
above, is a continuation of the Army's commitment to community involvement in the Schofield
Barracks Installation Restoration Program (IRP) and is required by CERCLA.
This decision document presents the selected remedial action for OU 2 at the Schofield Barracks,
Hawaii, chosen in accordance with CERCLA, as amended by SARA, and to the extent practicable, the
National Contingency Plan. The decision for OU 2 is based on the Administrative Record.
2.7 Scope and Role of Operable Unit
The scope of OU 2 consists of the groundwater system beneath Schofield Barracks. The objectives of
the OU 2 program are to:
• Assess the presence or absence of contamination within the groundwater system
• Assess the extent of contamination if contaminants are present
• Assess the risks to public health and the environment posed by contamination if contaminants
are present
• Identify and evaluate remedial alternatives for site cleanup if contaminants are present in levels
that could endanger public health and the environment
• Implement a preferred remedial alternative that assures protection of public health and the
environment
V
OU 2 addresses the contamination present in the groundwater beneath Schofield Barracks. Potential
sources of contamination to the groundwater system are addressed in OU 1 and OU 4 (the Former
Landfill). OU 3 addresses the potential presence of contamination at various other small sites on
Schofield Barracks. OU 2 is the only operable unit addressed in this ROD.
OU 2 addresses the principal threat to human health and the environment posed at this site by
minimizing human exposure to contaminated groundwater through treatment prior to its entering the
drinking water distribution system.
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PocWon Summary _
2.8 Stte Characterization
This section of the OU 2 ROD provides a summary of the results and data evaluation activities
undertaken as a part of the RI/FS for OU 2. Additional details regarding the results and evaluation of
data relevant to the groundwater system are presented in the OU 1, 2, and 4 PA/SI report (HLA,
119992a); Final OU 4 Phase H SAP (HLA, 1995a); the Draft OU 2 Feasibility Study Report (HLA, 1996b);
the Final OU 2 Remedial Investigation Report (HLA, 1996a); and the Final OU 1 RI Report (HLA,
1995b). A summary of the nature and extent of contamination and contamination fate and transport is
provided in Sections 2.8.1 and 2.8.2, respectively. -
Nature and Extent off Contamination
Groundwater was the only media investigated for OU 2. The only analytes detected above MCLs in the
groundwater system beneath Schofield Barracks and Wheeler were TCE, carbon tetrachloride,
antimony, and manganese. Contaminants were detected in two plume areas: (1) beneath the Former
Landfill and (2) beneath the Schofield Barracks East Range and Wheeler (East Range/Wheeler). The
horizontal extent of carbon tetrachloride, antimony, and manganese contamination, with the exception
of one detection of carbon tetrachloride at Well MW-2-3, was limited to the immediate vicinity of the
Former Landfill. The inorganic compounds antimony and manganese were detected above MCLs
inconsistently. Because of this inconsistency and because these inorganic compounds were not
detected above MCLs during the most recent sampling event, the detections of antimony and
manganese above MCLs are believed to be anomalous. Therefore, only TCE and carbon tetrachloride
were retained as chemicals to be addressed for the OU 2 FS. Figure 2.3 shows a contour map of the
horizontal extent of TCE greater than 5 jig/1 in the groundwater system beneath Schofield Barracks. The
data points in Figure 2.3 represent average concentrations of TCE in samples collected from the wells.
Figure 2.4 presents the detected organic compound analytical results from OU 2 samples for the four
sampling rounds. A more detailed explanation of the distribution of VOCs in groundwater beneath
Schofield Barracks is summarized in the OU 2 RI report.
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Decision Summary
The vertical distribution of TCE in the Former Landfill area appears to be relatively uniform with depth
from the top of the aquifer (275 feet msl) to approximately 0 feet msl. Data are not available "for greater
depths in the Former Landfill area. The vertical distribution of TCE in the East Range/Wheeler area
appears to increase with depth to about 195 feet msl and then decrease to below MCLs at approximately
5 feet msl.
Existing information indicates that ofisite wells have likely not been impacted by TCE or carbon
tetrachloride in levels above MCLs from either the Former Landfill area or the East Range/Wheeler area.
However, low concentrations (less than 5 pg/1) of TCE were detected in three ofisite wells located near
Kunia just southwest of Wheeler.
Contaminant Fate and Transport
As indicated in the previous section, the contaminants designated as COCs for the OU 2 FS are TCE and
carbon tetrachloride. This section summarizes the fate and transport processes that affect current and
potential migration of these COCs through both the vadose zone and the ground-water system.
Physical and chemical mechanisms that impact the fate and transport of TCE and carbon tetrachloride
were evaluated for both the vadose zone and the saturated zone. Results of the vadose zone
investigations indicated the following:
• The primary mechanism for contaminant transport in the vadose zone appears to be advecn've
flow of water containing COCs in a dissolved phase (i.e., contaminants move along dissolved in
the water).
• The primary direction of COC movement in the vadose zone is vertical, therefore, little lateral
spreading of contaminants in the vadose zone likely occurred.
• It was determined that contaminant migration in the vadose zone likely occurred primarily in
fractures or other remnant basaltic features in the saprolite zone, and that this migration
occurred primarily during high-intensity infiltration events (high-rainfall events which resulted
in surface ponding).
• The rate of migration of COCs in the vadose zone may be reduced by adsorption of chemicals
onto organic matter within the soil matrix (known as retardation). However, because of the low
amount of organic matter in the vadose zone, this mechanism is not considered significant.
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• The amount of COG reaching the water table may be reduced by biological degradation of the
contaminant in the vadose zone. However, few data are available to evaluate the impact of
degradation in the vadose zone, and thus this mechanism was not evaluated in detail.
• Results of field testing and computer modeling indicate that TCE (the most widespread COG)
could migrate through the vadose zone to the groundwater in approximately 10 years.
Results of the saturated zone investigations indicated the following:
• On a regional scale (greater than approximately 500 lateral feet), the aquifer material (fractured
basalt) appears to be hydraulically connected such that it behaves like porous aquifer material.
Therefore, preferred contaminant pathways (such as large single fractures) do not appear to be a
significant mechanism of offsite transport.
• As in the vadose zone, the primary mechanism of transport appears to be advective water flow
containing COCs in the dissolved phase and the direction of movement is primarily driven by
the direction of groundwater flow.
• Retardation and degradation may impact contaminant movement in the saturated zone.
However, no data are available to evaluate whether these phenomena have any impact on
migration within the saturated zone.
• Results of computer modeling indicate that under the most conservative assumptions (no
retardation or degradation), TCE concentration above the MCL could reach downgradient
receptors (to the south) in approximately 100 years.
2.9 Summary of Site Risks
A baseline risk assessment was prepared to evaluate the potential human and ecological risks posed by
chemicals detected in the groundwater at OU 2. This baseline risk assessment is provided as
Section 7.0 in the Final OU 2 RI Report (HLA, 1996a). The data collected during Phase I and n of the RI
were used as the source for the analytical data for the human health risk assessment (HRA) and the
ecological risk assessment (ERA). Because OU 2 is limited to the groundwater at Schofield Barracks,
groundwater is the only medium of concern for this risk assessment. Additionally, the only
contaminated water currently being used as a public drinking water supply is extracted from the
Schofield water-supply wells. However, this water is being treated by an air-stripping treatment system
prior to distribution and use so that the water quality meets the federal SDWA MCLs for public water
supplies. Consequently, the risks presented in the HRA reflect untreated groundwater and not actual
current exposures.
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Two separate areas of concern were evaluated: (1) the Former Landfill area and (2) the East
Range/Wheeler area. The Former Landfill area was evaluated using the data from four existing
groundwater monitoring wells (Figure 2.3). The East Range area was evaluated using data from
groundwater monitoring wells in the eastern portion of Schofield, in the Wheeler area, and the
Schofield Barracks water-supply wells.
Chemicals of potential concern (COPCs) were selected for risk assessment by comparing the
detected concentration to both the MCLs (primary or secondary) and the EPA Region IX PRG for
residential ingestion (EPA, 1995). If the maximum detected concentration exceeded the MCL, the
chemical was retained as a COPC. If an MCL was not available, the EPA Region IX PRG was used for
comparison. Four chemicals were initially retained as COPCs for the risk assessment: antimony,
carbon tetrachloride, manganese, and TCE. However, as discussed in Section 2.8.1, antimony and
manganese were detected inconsistently above MCLs and were not detected above MCLs during the
most recent sampling event, therefore the detections above MCLs are believed to be anomalous.
Therefore, only TCE and carbon tetrachloride were retained as COCs to be addressed in evaluating
remedial alternatives.
No current human populations with exposure to untreated groundwater were identified. Water
withdrawn from the Schofield Barracks water-supply wells is treated to achieve MCLs prior to
distribution and use. Therefore, the population of interest in the HRA is a future residential population,
both adults and children. Exposure pathways considered in the HRA are those commonly associated
with domestic use of water, namely ingestion of water, dermal contact with water, and inhalation of
volatile organic compounds (VOCs) during water use. VOCs may volatilize from groundwater and
eventually diffuse into the ambient air and subsequently be inhaled by a receptor. However, the low
concentrations of VOCs in the groundwater (less than 100 parts per billion [ppb]), the depth to
groundwater (approximately 500 to 600 feet), complex hydrogeology, and the inherent uncertainties in
estimating these exposures preclude a quantitative evaluation of exposures related to soil gas.
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Potential exposures to humans were evaluated for both average case and reasonable maximum exposure
(RME) scenarios. Different exposure and chemical intake assumptions were used to represent the
average and RME scenarios. Average and RME exposure point concentrations for COPCs in the
groundwater were estimated as the arithmetic mean and 95 percent upper confidence limit.
respectively, as recommended by EPA. Average and RME exposure point concentrations were
developed for (1) the Former Landfill area and (2) the East Range/Wheeler area. Additionally, because
Schofield Barracks Water-supply Well No. 4 is most commonly used as the source of water for
distribution, the maximum TCE concentration detected in this well was evaluated as a separate source.
Carcinogenic health effects (expressed as risk) and noncarcinogenic health effects (expressed as hazard
indices [HI]) were characterized by combining the estimated chemical intakes with the appropriate
toxicity factors (i.e., carcinogenic slope factors and noncarcinogenic reference doses). Only chronic
tenacity factors were used in the HRA. Oral toxicity factors were used to evaluate dermal exposures.
Table 2.1 presents the total carcinogenic and noncarcinogenic risks estimated for the adult and child
receptor for both the Former Landfill area and the East Range/Wheeler area.
The RME noncarcinogenic His exceed 1.0, which is the EPA benchmark for concern, for both the child
and adult resident for the Former Landfill area (maximum HI of 9.3, child receptor). However, the
majority of the estimated HI is a result of antimony detected in landfill wells. Antimony was
inconsistently detected within a given well and between wells hi the Former Landfill area. Because
these inconsistencies suggest anomalous data not representative of actual site conditions, and the fact
that the potential for exposure to this groundwater is limited, the elevated His related to the Former
Landfill groundwater are not considered significant
All of the estimated carcinogenic risks for both areas are either less than or within the EPA acceptable
risk range of 1 x 10"* to 1 x 10"*. The estimated risk is associated with pretreated water prior to
distribution and is not reflective of current exposure conditions because the pretreated water is not used
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for domestic purposes. Following treatment by air stripping, the water supply taken from any of the
Schofield Barracks water-supply wells meets MCLs, the federal water quality standards for public
distribution water.
In addition to the quantitative HRA, a qualitative ERA was also developed. Because groundwater from
two wells southwest of Schofield Barracks is used to supplement irrigation water for commercial
pineapple fields, the potential for adverse effects to pineapple plants exposed to TCE in irrigation water
was evaluated. However, adverse effects to pineapple or other plants resulting from low concentrations
of TCE in irrigation water are not expected for several reasons: (1) TCE has a low adsorption capacity
coefficient indicating ready transport through the soil profile, (2) TCE rapidly evaporates from water
and soil to the atmosphere, (3) dilution with other sources of irrigation water will further reduce the
TCE concentrations, and (4) crop impairment from exposure to TCE in growth media has not been
reported in literature. .., .
Actual or threatened releases of hazardous substances from this site, if not addressed by implementing
the response action selected by this ROD, may present an imminent and substantial endangerment to
public health, welfare, and the environment
2.10 Description off Alternatives
Because of the unique and complex hydrogeological conditions at Schofield Barracks and because a
source, or sources, of TCE detected in the Schofield Barracks water-supply wells could not be
identified, it became apparent early in the OU 2 RI/FS program that characterizing the groundwater
system to the extent necessary to evaluate remedial alternatives for a full range of general response
actions would be extremely expensive. Therefore, preliminary FS evaluations were initiated during
Phase I of the RI to allow focusing of Phase n RI evaluations and subsequent FS evaluations.
Development of general response actions that would satisfy remedial action objectives for the site was
undertaken during the Phase I RI. The following general response actions that would satisfy remedial
action objectives were identified:
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• Restoration of the contaminated groundwater system by pumping, treating, and reinjecting the
groundwater
• Containment of the contaminated groundwater plume by boundary pumping, treating, and
reinjecting
• Treatment of contaminated groundwater at the wellhead when it is extracted from the
groundwater. system for domestic use. The water within the aquifer will be restored over time
through natural attenuation.
Because of the complex hydrogeology, depth to groundwater, and aquifer characteristics, restoration of
the groundwater through a pump and treat remedy was not considered practicable. Therefore, only two
general response actions were considered under the OU 2 Feasibility Study:
1. Containment of the contaminated groundwater plume by a boundary pump and treat system,
and
2. Reduction of risk via:
• Continued treatment for COCs present in extracted groundwater at the Schofield
Barracks Supply Wells by air stripping at the wellhead followed by discharge of the
treated water to the distribution system
• The Army must consult with EPA and the DOH prior to abandoning the Schofield
Barracks water supply wells, because production at these wells may help to control
plume migration
• Long-term sampling and analysis of water supply wells, agricultural wells, and
monitoring wells in the region
• Implementation of the contingency of wellhead treatment on any water supply wells
that are impacted by the plume from Schofield above one-half the MCL as established
under the SDWA
• Upgrading the treatment system or paying any increment costs caused by
contamination from Schofield at wells that already have a treatment system in place
• Conducting five-year site reviews with the State of Hawaii and the U.S. EPA.
A preliminary evaluation was performed for representative alternatives for each of these general
response actions. The results of this evaluation (Appendix A of the OU 2 Feasibility study (HLA,
1996a] indicated that the pump and treat remedy, even for containment, was impracticable and as such,
it was not carried through the detailed analysis comparison. The evaluation concluded that the
wellhead treatment option would be protective of human health and the environment. Because this
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remedy does not restore groundwater within the aquifer, a TI waiver must be invoked, as described in
the Justification for Technical Impracticability Waiver at Schofield Barracks for the Ground Water Record
of Decision, which is part of the Administrative Record for Schofield Barracks.
The feasibility study for OU 2 initially evaluated and developed five alternatives for the wellhead
treatment systems in accordance with CERCLA, the NCP, and relevant EPA and state guidelines,
policies, and procedures. Alternative 1 (no actin) is developed as an NCP requirement and
Alternatives 2 through 5 were developed for wellhead treatment of the extracted contaminated OU 2
groundwater, if necessary.
The feasibility study for OU 2 initially evaluated and developed five alternatives in accordance with
CERCLA, the NCP, and relevant EPA and state guidelines, policies, and procedures. The alternatives
have been developed as a contingency. Alternative 1 (no action) is developed as an NCP requirement
and Alternatives 2 through 5 were developed for wellhead treatment of the extracted contaminated
OU 2 groundwater, if necessary. Through the screening of alternatives phase of the FS process,
Alternatives 3 (carbon adsorption treatment) and 5 (ultraviolet hydrogen peroxide oxidation treatment)
were considered similar in effectiveness and implementability to Alternatives 2 and 4, but had higher
costs and were eliminated from further evaluation. The remaining three alternatives evaluated in the
OU 2 FS are summarized below. All three remaining alternatives contain the following institutional
controls: groundwater monitoring, and five-year site review. Hawaii DOH requires any new wells
installed as water-supply wells under SDWA to be sampled for the analytes SDWA-specified, which
include TCE and carbon tetrachloride. Additionally, any new wells that are installed within the area
covered by the long-term monitoring network will be added to the existing long-term monitoring
network presented in Figure 2.4. Should these new wells be or become contaminated with COCs that
can be directly attributed to Schofield Barracks, the selected wellhead treatment alternative would be
implemented to address this contamination. The purpose of the groundwater monitoring program will
be to assess groundwater conditions and to track the movement of the TCE- and carbon tetrachloride-
contaminated groundwater plumes to provide an early warning of potential contamination. Five-year
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site reviews will be conducted to ensure that human health and the environment are protected. The
site review will use the groundwater monitoring program data to assess whether additional action is
warranted.
The location-, chemical-, and action-specific applicable or relevant and appropriate requirements
(ARARs] considered for these three remaining alternatives are summarized in Tables 2.2 through 2.4.
2.10.1 Alternative 1 • No Action/Institutional Controls
Alternative I includes the following components:
• No action
• Institutional controls
Long-term groundwater monitoring
Five-year site reviews
Under Alternative 1 no further action would take place to reduce/control chemicals in OU 2
groundwater. Natural fate processes, including degradation and attenuation, would continue to reduce
contaminant concentrations with time in OU 2 groundwater. The No Action alternative is required as
part of the NCP to provide a baseline against which to compare the other alternatives.
2.10.2 Alternative 2 • Air Stripping
Alternative 2 includes the following components:
• Treatment of COCs present in groundwater at only those points where it is extracted for
domestic use by air stripping at the wellhead prior to discharge to distribution system
• Institutional controls
Long-term groundwater monitoring
Five-year site reviews
The treatment component is described below and the institutional control components are described in
Section 2.10.1.
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Air-stripping Treatment and Discharge to Distribution System
Air stripping will be used to reduce the TCE and carbon tetrachloride concentration in groundwater to
levels below the PRGs, which are the SDWA MCLs. A process flow diagram for the air-stripping
process is presented in Figure 2.5. The first component of the air stripping system is a bag filtration
unit for the removal of suspended solids from the extracted groundwater. The air-stripping unit then
removes TCE and carbon tetrachloride from the filtered groundwater. Treated water from the air-
stripping unit is routed to a distribution system for domestic use.
For cost estimating, treatment system conceptual design, and comparative analysis purposes,
Alternative 2 assumes the treatment of groundwater from three current or future impacted groundwater
production wells that are used for domestic water-supply purposes that could be impacted by
contaminated groundwater from Schofield Barracks. The process will include one bag filter unit per
well, one air-stripper unit per well, and a common collection and distribution system for all three wells
and treatment units. The installed system will consist of three treatment units, each rated at
1,500 gallons per minute (gpm), which will be connected to the existing three production wells.
Operational cost estimates are based on the assumption that the system will operate such that only two
wells and two treatment units are extracting and treating groundwater at any given time. Thus, one
well and one treatment unit are on standby or in maintenance. This configuration provides for
continuous treatment of 3,000 gpm of groundwater.
The three air-stripping units will be constructed on a common concrete pad. The treatment facility will
be fenced to prevent public entry and potential exposure to untreated groundwater. The treatment
units will be incorporated into the existing production well/distribution system pipeline to provide for
discharge into the distribution system.
Suspended solids removed by the bag filtration units will be disposed hi a nonhazardous landfill. The
State of Hawaii allows 0.1 ton per year (T/yr) of each hazardous constituent to be emitted uncontrolled
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into the atmosphere (Hawaii Administrative Rules [HARJ, Title 11, Chapter 60.1). Based on the
mayi'miim influent concentrations of TCE (25 /ig/1) and carbon tetrachloride (8.2 /jg/1) anticipated in
groundwater (see Table 2.5) that could potentially impact water-supply wells to the south of Schofield
Barracks and the projected flow rate of 1,500 gpm per well per air stripper, the air-stripper vapor
discharge will be below .1 T/yr (Table 2.7) and will not require treatment.
2.10.3 Alternative 4 • Ozone/Hydrogen Peroxide Treatment
Alternative 4 includes the following components:
• Treatment of COCs present in extracted groundwater with ozone/hydrogen peroxide oxidation
and discharge to the distribution system
• Institutional controls
Long-term groundwater monitoring
Five-year site reviews
The treatment component is described below and the institutional control components are described in
Section 2.10.
Ozone/Hydrogen Peroxide Oxidation Treatment and Discharge to Distribution System
Ozone/hydrogen peroxide will be used to reduce the TCE and carbon tetrachloride concentrations in
the groundwater to levels below the PRGs, which are the SWDA MCLs. A process flow diagram for the
ozone/hydrogen peroxide oxidation process is presented in Figure 2.6. The first component of the
ozone/hydrogen peroxide oxidation treatment system is a bag filtration unit for the removal of
suspended solids from the extracted groundwater. The ozone/hydrogen peroxide oxidation unit then
removes TCE and carbon tetrachloride from the filtered groundwater. Treated water from the
ozone/hydrogen peroxide oxidation unit is routed to a distribution system for domestic use.
For cost estimating, treatment system conceptual design, and comparative analysis purposes,
Alternative 4 assumes the treatment of groundwater from three current or future groundwater
production wells that are used for domestic water-supply purposes that could be impacted by
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contaminated groundwater from Schofield Barracks. The process will include one bag filter unit per
well, one ozone/hydrogen peroxide oxidation unit per well, and a common collection and distribution
system for all three wells and treatment units. The installed system will consist of three treatment
units, each rated at 1,500 gpm, which will be connected to the existing three production wells.
Operational cost estimates are based on the assumption that the system will operate such that only two
wells and two treatment units are extracting and treating groundwater at any given time. Thus, one
well and one treatment unit are on standby or in maintenance. This configuration provides for
continuous treatment of 3,000 gpm of groundwater.
The three ozone/hydrogen peroxide oxidation units will be constructed on a common concrete pad.
The treatment facility will be fenced to prevent public entry and potential exposure to untreated
groundwater. The treatment units will be incorporated into the existing production well/distribution
/
system pipeline to provide for discharge into the distribution system.
Suspended solids removed by the bag filtration units will be disposed of in a nonhazardous landfill.
Offgas generated by the ozone/hydrogen peroxide oxidation units will be treated with a catalytic
oxidizer to destroy excess ozone prior to release to the atmosphere.
2.11 Summary off Comparative Analysis of Alternatives
This section provides a comparison of the alternatives described in Section 2.10 with respect to the
following nine NCP criteria: (1) overall protection of human health and the environment; (2) com-
pliance with ARARs; (3) long-term effectiveness and permanence; (4) reduction in toxicity, mobility,
and volume; (5) short-term effectiveness; (6) inaplementability; (7) cost; (8) state acceptance; and
(9) community acceptance. As previously discussed, each of the alternatives incorporates
commonalties including groundwater monitoring and five-year site reviews. Accordingly, these
components of the alternatives were not evaluated in the comparative analysis. Table 2.6 provides a
summary of the comparative analysis of alternatives.
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2.11.1 Overall Protection of Human Health and the Environment
Alternative 1 does not provide any additional protection of human health and the environment.
Alternatives 2 and 4 consist of groundwater treatment at the wellhead prior to distribution for domestic
use. Alternatives 2 and 4 both offer an increase in protection of human health and the environment.
Alternatives 2 and 4 remove COCs from the groundwater and provide approximately equal protection of
human health and the environment
2.11A Compliance with ARARs
Alternative 1, no action, does not achieve chemical-specific ARARs. There are no location-specific or
action-specific ARARs for this alternative.
Alternatives 2 and 4 will meet the action-specific ARARs listed in Table 2.4. Neither Alternative 2 nor
4 involves generation of fugitive dust emissions except during construction for which appropriate
preventative measures will be taken and neither alternative will exceed the State of Hawaii air
discharge standards for emissions of volatile organic compounds (VOCs) from point sources.
Both Alternatives 2 and 4 will meet the MCLs required to discharge the treated groundwater into the
water distribution systems. The proposed wellhead treatment systems will be co-located with existing
and future supply wells and will meet the potential location-specific ARARs listed in Table 2.2.
None of the wellhead treatment options meets the chemical-specific ARARs for restoration of the
groundwater to MCLs. As discussed in Section 2.10, the RI Report, and the FS Report, the unique and
complex hydrogeologic conditions at Schofield Barracks (i.e., 550 to 650 feet thick vadose zone and
highly transmissive fractured basaltic bedrock aquifer) required a unique approach to address
groundwater contamination. A TI waiver to the MCL is therefore justified based on the following
discussion. More detailed discussions are contained in the RI Report (HLA, 1996b), the OU 2 FS Report
(HLA, 1996a), the Justification for Technical Impracticability Waiver at Schofield Barracks for the Ground
Water Record of Decision, and the minutes of the February 24,1994 In-progress Review (IRP).
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2.11.2.1 High Groundwater Volume
The high transmissivity of the Schofield High Level Water Body and the associated high volume of
water flowing through the system would require tremendous extraction and treatment capacities to
address a plume of any substantial size. The Schofield supply wells, pumping at 4 to 5 million gallons
per day, have done nothing to reduce the concentrations of TCE in the aquifer since the stripping
towers were installed in 1986. The average concentration of TCE in the supply wells has remained
steady at approximately 25 to 30 jig/1 over that time period. Modeling estimates presented at the
February 24,1994, JPR projected extraction/reinjection rates of from 17 million to 56 million gallons per
day would be required to restore the aquifer over a period of 15 to 30 years (depending on the plume
size and location). An extraction/reinjection rate of approximately 216 million gallons per day was
estimated to be required to restore the groundwater based on application of the OU 2 RI groundwater
model using current information on the plume boundaries. In addition to the technical difficulties
associated with installing and operating such a vast network of extraction/injection well systems in a
complex bedrock aquifer such as the Schofield High Level Water Body, the power required to run such
a network is not currently available within the Oahu power grid. A new power plant with associated
engineering and operating difficulties would be required to implement such a remedy.
2.11.2.2 Potential Impacts to Basal Aquifers
In addition, the sustainable yield of the Schofield High-Level Water Body has been estimated by the
Honolulu Board of Water Supply at 104 million gallons per day. Of this, approximately 76 Trillion
gallons per day is required as recharge to the Honolulu-Pearl Harbor Basal Aquifer to avoid salt water
intrusion. Currently 10.7 million gallons per day are pumped by Schofield plateau wells, leaving
approximately 17.7 million gallons per day of increased usage. This would limit the extraction capacity
of a groundwater treatment system network and would make the groundwater resource unavailable for
productive use or would require installation of a reinjection well network As discussed above, the
projected extraction rate required to restore the Schofield High Level Water Body is estimated at
approximately 40 million gallons per day which would exceed the extraction limits and would thus
require reinjection.
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2.11.2.3 Protectiveness of Wellhead Treatment
The limitation on groundwater extraction likewise puts an upper bound on the future number of
production wells potentially requiring treatment, which, in turn, further supports the Army's selection
of wellhead treatment of impacted wells rather than active pump and treat of the aquifer. Wellhead
treatment will provide adequate protection of human health and the environment in a cost-effective
manner and will meet the intent of the Safe Drinking Water Act MCLs by ensuring that the water-
supply systems are providing safe drinking water to Oahu residents.
2.11.3 Long-term Effectiveness and Permanence
Alternative 1 does not provide any additional risk reduction over the long term. Alternatives 2 and 4
provide an increase in long-term effectiveness and permanence by treating extracted OU 2 groundwater
prior to distribution for domestic use. The treatment technology to be employed by both Alternatives 2
and 4 are proven technologies with a long track record of effectiveness and reliability. Monitoring of
the groundwater supplies as required under the Safe Drinking Water Act, further ensures that TCE and
carbon tetrachloride levels in the treated water supply will be maintained below the MCL. The
technology employed in Alternative 4 breaks down TCE and carbon tetrachloride into nonhazardous
products eliminating concerns about residual contamination. Although Alternative 2 simply removes
the TCE and carbon tetrachloride from the water through volatilization, modeling projections indicate
that the emissions from the air stripping towers will be low and are well below EPA's acceptable risk
ranges (see discussion in Section 2.13, Protection of Human Health and the Environment).
2.11A Reduction In ToxicKy, Mobility, and Volume
Alternative 1 does not provide a reduction in toxicity, mobility, or volume except through natural
attenuation of COCs in the OU 2 groundwater system. Alternative 4 provides an increased reduction in
toxicity, mobility, and volume by destroying the COCs in the ozone/hydrogen peroxide oxidation unit.
Alternative 2 also provides an increased reduction in toxicity, mobility, and volume of COCs although
the COCs are transferred to the atmosphere as VOCs rather than destroyed.
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2.11.5 Short-term Effectiveness
The short-term conditions at the site would remain unchanged under Alternative 1 because no action is
implemented. Alternatives 2 and 4 will have minimal short-term impacts to the community and
workers associated with construction of a concrete slab and installation of the treatment system
equipment. Alternatives 2 and 4 will likely create some minimal short-term ecological and environ-
mental effects due to construction activities from dust generation, vegetation clearing, and general
construction noise.
2.11.6 Implementability
The only technical aspect of Alternative 1 is the implementation of the groundwater monitoring
program to re-evaluate the site in five years. Groundwater monitoring is also a component of
Alternatives 2 and 4 to support decisions on implementing remedial action at impacted wells. The
Army, Hawaii Department of Health and EPA. as well as the Honolulu Board of Water Supply and the
public, will be involved in the review of monitoring data to analyze trends and to determine when
wellhead treatment is required.
Alternatives 2 and 4 are considered to be technically implementable. Both treatment systems involve
components that are readily available from several vendors.
2.11.7 Cost
The net present worth of Alternative 1, Alternative 2, and Alternative 4 are $1,350,000, $3,900,000, and
$5,910,000, respectively. A breakdown of capital cost, operation and maintenance (O&M) cost, and net
present worth for each alternative is presented in Table 2.8.
2.11.8 State Acceptance
As indicated by DOH approval of the Final OU 2 FS and Proposed Plan, Alternative 2 is more
acceptable to the State than Alternatives 1, 3,4, and 5.
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2.11.9 Community Acceptance
Community acceptance is documented in Section 3.0 (Responsiveness Summary).
2.12 Selected Remedy
Based on consideration of the requirements of CERCLA, the detailed analysis of alternatives, and public
comment, the Army, EPA, and DOH have determined that a remedy with the following components is
the preferred remedy for Schofield Barracks OU 2:
• Continued treatment for COCs present in extracted groundwater at the Schofield Barracks
Supply Wells by air stripping at the wellhead followed by discharge of the treated water to the
distribution system
• The Army must consult with EPA and DOH prior to abandoning the Schofield Barracks water
supply wells, because production at these wells may help to control plume migration
• Long-term sampling and analysis of water supply wells, agricultural wells and monitoring wells
in the region
• Implementation of the contingency of wellhead treatment on any water supply wells that are
impacted by the plume from Schofield Barracks above one-half the MCL as established under
the SDWA
• Upgrade the treatment system or pay any incremental costs caused by contamination from
Schofield Barracks at wells that already have a treatment system in place
• Conduct five-year site reviews with the State of Hawaii and the U.S. EPA.
The details of the monitoring plan, evaluation process for implementation of wellhead treatment, and
description of conditions at existing water wells may be found in the Final Operation and Maintenance
and Long-Term Groundwater Monitoring Plan for Operable Unit 2, Schofield Army Barracks, which is an
addendum to this ROD.
Alternative 2 (air stripping) is the preferred alternative for the wellhead treatment systems. The
comparative analysis indicates that Alternative 2 is preferred to Alternative 4 (ozone/hydrogen
peroxide/oxidation) with respect to cost However, Alternative 2 is considered equal to Alternative 4
with respect to protection of human health and the environment, compliance with ARARs, long-term
effectiveness and permanence, short-term effectiveness, and implementability.
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Decision Summary
The major costs associated with Alternative 2 are presented in Table 2.9.
For comparative analysis purposes a treatment system conceptual design was assumed for treatment of
groundwater from three current or future impacted groundwater production wells that are used for
domestic water-supply purposes that could be impacted by contaminated groundwater from Schofield
Barracks. The conceptual air stripper treatment system design consists of three treatment units, each
rated at 1,500 gpm, connected to three existing domestic water-supply production wells. However,
there are potentially seven existing water production well systems with a varying number of production
wells at varying flow rates that could be impacted by Schofield Barracks groundwater. Three of the
seven existing production well systems are currently treating the extracted groundwater to remove
pesticides using carbon adsorption. If TCE-contaminated water from Schofield Barracks impacts any of
the existing three water-supply carbon adsorption systems, the carbon usage rates may increase over
their normal carbon usage rates at these systems. The impact to carbon usage at these three systems
was modeled to estimate the possible carbon usage increase. The results of the modeling are
summarized in Appendix B. The modeling results indicate that the carbon usage rate will likely
increase as the concentrations of TCE increase. Therefore, the Army will be responsible for sharing
some carbon usage costs until the air stripper system is installed.
2.13 Statutory Determinations
Under its legal authorities, EPA's primary responsibility at Federal Facility NFL sites is to oversee
remedial actions that achieve adequate protection of human health and the environment. In addition,
Section 121 of CERCLA establishes several other statutory requirements and preferences. These specify
that, when complete, the selected remedial action for this site must comply with applicable or relevant
and appropriate environmental standards established under federal and state environmental laws unless
a statutory waiver is justified. The selected remedy also must be cost effective and utilize permanent
solutions and alternative treatment technologies or resource recovery technologies to the maximum
extent practicable. Finally, the statute includes a preference for remedies that employ treatment which
33537 07.04.00 Harding Lawson Associates 2-25
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Decision Summary
permanently and significantly reduces the volume, toxitity, or mobility of hazardous wastes as their
principal element. The following sections discuss how the selected remedy meets these statutory
requirements.
Protection of Human Health and the Environment
Overall protection of human health and the environment will be provided by the selected remedy prior
to distribution of the OU 2 groundwater. Based on the baseline risk assessment (HLA, 1996a), no
current populations with exposure to contaminated OU 2 groundwater were identified onsite or offsite.
Additionally, groundwater modeling was performed to evaluate contaminant migration both with and
* -...
without the impacts of retardation and degradation. The modeling results using no degradation and
retardation indicate that the OU 2 plume may migrate offsite to the south, flowing across the southern
groundwater dam at concentrations above 5 tig/I within 5 years but will not likely impact current
downgradient water-supply wells for approximately 100 years. Modeling results using high retardation
and degradation indicate no impact to downgradient water-supply wells. Alternative 2 was developed
to address the contaminated OU 2 plume if it does migrate offsite, the COC concentrations exceed the
MCLs, and the OU 2 groundwater is extracted in new or existing potable water-supply wells. Contami-
nated OU 2 groundwater will be treated by an air stripper at the wellhead to remove COCs to concen-
trations below the MCLs prior to distribution for domestic use. Because air stripping does not destroy
TCE or carbon tetrachloride prior to vapor discharge to the atmosphere, an air dispersion model and a
theoretical risk assessment were performed to evaluate potential health risks posed by the air stripper
vapor discharge. To perform a theoretical risk assessment for the constituents, the EPA single-source
dispersion model SCREENS (EPA, 1995) was first used to calculate airborne concentrations of TCE and
carbon tetrachloride within 3,281 feet (1,000 meters) of the air strippers. Using model results and EPA
guidance, the highest annual average air concentration for TCE was predicted to be 0.079 micrograzns
per cubic meter (fig/m3). The equivalent concentration for carbon tetrachloride was predicted to be
0.026 ng/m3. The model results indicated that the mayinnjm concentration would occur at a distance of
2,162 feet (659 meters) from the air strippers.
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Decision Summary
Using the SCREENS model results, a theoretical risk assessment was performed for the air stripper
airborne concentrations of TCE and carbon tetrachloride. The cumulative risks associated with the
predicted concentrations of the constituents are well below EPA's acceptable cancer risk range of 10~* to
10*6. In addition, the noncancer hazard indices are well below EPA's acceptable level of 1.0. The
calculated cumulative cancer risk for the two constituents was 2.2 x 10"7 and the calculated cumulative
hazard index was 0.012. Based on the dispersion model and risk assessment results, no significant
health risks are expected for the constituents calculated to be released from the conceptual design air
strippers. Additionally, institutional controls as discussed in Section 2.10 will be implemented to
reduce the chance of inadvertent exposure.
Natural attenuation will be the primary mechanism for contaminant concentration reduction in the
aquifer (Schofield High-level Water Body) eventually eliminating the need for treatment. Periodic
groundwater monitoring and five-year site reviews will provide data to indicate when contaminant
levels in groundwater have attained MCLs.
Compliance with ARARs
The location-, chemical-, and action-specific ARARs are listed below:
• Location-specific ARARs:
16 United States Code (USC) 661 et seq., 662 and 663, requiring actions to be taken to
prevent, mitigate, or compensate for project-related damages or losses to fish and
wildlife resources.
Clean Water Act (CWA) 404, 33 CFR 320-330, and 40 Code of Federal Regulations
(CFR) 230, prohibiting discharges that cause or contribute to significant degradation of
the water of ecosystems.
HC 183D-61 et seq., prohibiting interference with wild birds or their nests.
CWA 404, prohibiting the discharge of fill material into aquatic ecosystems that would
jeopardize endangered, threatened, or rare species.
HC 194D-4,16 USC 1531 et seq., 50 CFR 402 prohibiting actions that jeopardize
endangered or threatened species or critical habitat of such species as designated in
50 CFR 17, 50 CFR 226, or 50 CFR 227.
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Decision Summary
• Chemical-specificARARs:
40 CFR, Part 141, (b) and (g), defining SDWA MCLs.
40 CFR, Part 141, (f), defining SDWA maximum contaminant level goals (MCLGs).
• Action-specific ARARs:
Hawaii Administrative Rule (HAR) 1 l-60.1-33(a)(l)-(7) and (b). prohibiting the dis-
charge of visible fugitive dust emissions beyond the property lot line on which the dust
originates and requiring precautions to prevent fugitive dust emissions.
HAR 11-60.1-68, requiring monitoring of VOC emissions if emissions are greater than
1 ton per year for each hazardous air pollutant.
40 CFR, Part 141, (b) and (g), defining MCLs.
While the selected alternative will treat groundwater at the wellhead to concentrations below the MCLs,
a waiver for the chemical-specific ARAR, as applied to the contaminated aquifer, is required based on
the technical impracticability of groundwater restoration to below the MCL concentrations. A detailed
justification for the TI waiver is provided in Section 2.11.2 of this ROD.
Other Criteria, Advisories, or Guidance To Be Considered for Remedial Action
In implementing the selected remedy, EPA and the State of Hawaii have agreed to consider a number of
procedures that are not legally binding (known as to be considered fTBCs]). These include the
following:
• 40 CFR 6.302(g) and (h), requiring actions to be taken to prevent, mitigate, or habitat
compensate for project-related damages or losses to fish, wildlife resources, or critical habitat.
• EPA Office of Water Lifetime Health Advisories for 70-kg Adult, May 1995, defining tnayim^im
recommended concentration of a given chemical in drinking water.
EPA Office of Water Health Advisory, May 1995, defining the concentration of a given
chemical in drinking water that will result in one excess cancer death in one million
people.
40 CFR 300.430(a)(l)(iii)(D), requiring institutional controls to prevent or limit exposure
to hazardous substances, pollutants, or contaminants.
Cost Effectiveness
The selected remedy is cost effective, providing overall effectiveness proportional to its costs. The net
present worth of the selected remedy is $3,990,000. While Alternative 1 offers the lowest estimated
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Decision Summary
cost, it does not provide long-term effectiveness. Considering Alternatives 2 and 4 provides comparable
long-term effectiveness, but the estimated cost of Alternative 2 is less than Alternative 4, Alternative 2
provides the best combination of cost and long-term effectiveness.
Utilization of Permanent Solutions and Alternative Technologies to the Maximum Extent
Practicable
The U.S. Army, in coordination with EPA and the State of Hawaii, 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 OU 2. The selected remedy provides the best balance of tradeoffs in
terms of long-term effectiveness and permanence; reduction in toxicity, mobility, or volume; short-term
effectiveness; implementability; and cost.
Although Alternative 4 is comparatively effective in the long term, Alternative 4 has a greater estimated
cost. The selected remedy addresses the principal threat posed by the contaminated OU 2 groundwater
efficiently and cost effectively.
Preference for Treatment as a Principal Element
The statutory preference for remedies that employ treatment as a principal element is satisfied by the
selected remedy. The principal threat of the site is the potential for domestic use of contaminated
groundwater with COC concentrations above PRGs. The selected remedy adequately addresses this
threat by treating the OU 2 groundwater at the wellhead to remove COCs to concentrations below the
PRGs prior to distribution for domestic use.
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Table 2.1: Summary off Noncarcinogenic and Carcinogenic Risks for OU 2
Hazard Index
Receptor/Pathway
East Range Area - Adult
Groundwater Ingestion
Groundwater VOC Inhalation
Groundwater Dermal
Total
Maximum TCE* - Adult
Groundwater Ingestion •
Groundwater VOC Inhalation
Groundwater Dermal
Total
Former Landfill - Adult
Groundwater Ingestion
Groundwater VOC Inhalation
Groundwater Dermal
Total
East Range Area - Child
Groundwater Ingestion
Groundwater VOC Inhalation
Groundwater Dermal
Total
Maximum TCE* - Child
Groundwater Ingestion
Groundwater VOC Inhalation
Groundwater Dermal
Total
Former Landfill - Child
Groundwater Ingestion
Groundwater VOC Inhalation
Groundwater Dermal
Total
Average
6.39E-02
1.32E-02
9.91E-03
8.70E-02
1.56E-01
NA
7.43E-02
2.30E-01
4.31E-01
7.45E-02
1.04E-02
5.16E-01
1.70E-01
3.52E-02
2.61E-02
2.32E-01
4.16E-01
NA
1.96E-01
6.11E-01
1.15E+00
1.99E-01
2.75E-02
1.38E+00
RME
3.96E-01
3.12E-02
2.23E-02
4.50E-01
6.23E-01
NA
1.04E-01
7.27E-01
2.75E+00
2.84E-01
2.91E-02
3.07E+00
1.20E+00
9.48E-01
5.88E-02
1.35E+00
1.89E+00
NA
2.74E-01
2.16E+00
8.35E4-00
8.62E-01
7.68E-O2
9.29E+00
Carcinogenic Risk
Average RME
2.33E-07
2.37E-07
8.42E-08
5.55E-07
1.32E-06
1.44E-06
6.31E-07
3.40E-06
5.02E-07
4.50E-07
8.63E-08
1.04E-06
2.08E-07
2.11E-07
7.40E-08
4.92E-07
1.18E-06
1.28E-06
5.54E-07
3.01E-06
4.46E-07
4.00E-07
7.58E-08
9.22E-07
4.67E-06
2.41E-06
6.31E-07
7.72E-06
1.76E-05
9.62E-06
2.94E-06
3.02E-05
1.30E-05
5.87E-06
8.15E-07
1.97E-05
2.84E-06
1.46E-06
3.32E-07
4.63E-06
1.07E-05
5.83E-06
1.55E-06
1.81E-05
7.91E-06
3.56E-06
4.30E-07
1.19E-05
NA Not applicable
OU Operable unit
RME Reasonable maximum exposure
TCE Trichloroethene
VOC Volatile organic compound
* Based on maximum depth-specific sampling result from the Schofield Barracks water-supply wells.
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Table 2.2i Location-specific Applicable or Relevant and
Appropriate Requirements for Sehofteld Barracks OU 2
Location Characteristic!*)
Prflr«qulflle(s)
Raquiremenl(s)
Cltation(s)
WilderneM areas, wildlife resources,
wildlife refuges, or scenic rivers
• Within (iron affecting stream or river •
and - presence of fish or wildlife
resources
Location encompassing aqunllc
ecosystem with dependent fish,
wildlife, other aquatic life, or hnbitnt
Presence of wild birds or their nests
Presence of fish or wildlife resources;
nctlon by federal ngency Ihnl results
in the control or structural
modification of a natural stream or
body of water
Offslte response action
Actlon(s) Involving the discharge of
dredge or fill material Into aquatic
ecosystem
The effects of water-related projects on fish and
wildlife resources must be considered.
Action must be taken to prevent, mitigate, or
compensate for project-related damages or losses to
fish and wildlife resources.
Offslto actions that alter a resource require
consultation with the FWS. NMFS, and/or the
appropriate state agency.
Consultation with the responsible agency Is also
strongly recommended for onslte actions.
Degradation or destruction of aquatic ecosystems must
be avoided to the extent possible. Discharges that
cnuse or contribute to significant degradation of the
water of such ecosystems are prohibited.
The Intentional, knowing, or reckless taking, catching,
Injuring, killing, destroying, or keeping In captivity or
possession of wild birds Is prohibited.
Damaging or destroying the nests of wild birds Is
prohibited.
Fish and Wildlife Coordination Act
(16 USC 661 ef sen.). §§662 and 663 •
'applicable
40 CFR §6.302(g) (applies to federal
agencies only) • TBC
Clean Water Act §404 - applicable
40 CFR §230 • applicable
33 CFR §320-330 • applicable
HC §1830-61 ef sea. • applicable
Endangered, threatened, or rare species
• Presence of endangered or threatened
species or critical habitat (see above
citation) of same within an aquatic
ecosystem as defined In 40 CFR
§230.3(c)
• Presence of federal or stale
endangered or threatened species
• Presence of endangered or threatened
33537 07.0« ""
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Action Involving discharge of dredge
or fill material into aquatic ecosystem
Action that Is likely to jeopardize
Dredge or fill material shall not be discharged Into an
aquatic ecosystem If It would Jeopardize such species
or would likely result In the destruction or adverse
modification of a critical habitat of the species.
The taking of any threatened or endangered species
within the state Is prohibited.
Actions that jeopardize species/habitat must be
Clean Water Act §404 • applicable
40 CFR §230.10(b) • applicable
HC §1950-4 • applicable
Endangered Species Act of 19Z3M6
I^fl
of 2
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Table 2.2 (continued)
LocnUon Cnaraclorlstlc(i) Prerequlilte(s) Requirement)*) Clt>Uon(s)
apocloi -or- crltluil hnlilini of inch species or destroy or adversely nvoldod or «|>|>ro|irlitle mlllgnllon moRsuros Inkon. USC 1531 or tea,.) • applicable
species ns doilgnnloil In SO CFK §17. modify critical habitat
50 CFK §220. or 50 CFH §227 • Offsllo actions thai affect spoeloa/habllM require • SO CFR §402 • applicable
conciliation with DO). FWS, NMFS. and/or ilale
agonclei. at approprlato. to ensure thai proposed • 40 CFR $6.302(h) • TBC
actloni do not jeopardize the continued existence of
the tpeclea or adversely modify or destroy critical • Fish and Wlldllfo Coordination Act
habitat. (16 USC 661 tt «*j.) • applicable
• Consultation with the responsible agency U aj*o
strongly recommended for onslto action*.
Source: Unllod Slnlos Army Environmental Cantor
CFR Coda of Fodarnl Rogulnlloni
DOI Do|),,rlmont of Interior
FWS U.S. Flih nnd Wlhlllfo Service
IIC IInwnll Citation
NMFS Notional Marino Fisheries Service
TIIC To bo conalclorod .
USC United States Code
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Table 2.3: Chemical-specific Applicable or Relevant and Appropriate
Requirements and "To-Be-Considered" Guidance for
Cleanup of Groundwater at Schofield Barracks OU 2*
Relevant and ADDrooriate Reauirements
Chemical
Acetone
Benzene
bis(2-Etbylhexyl)phthalate
SDWAMCLs'
(mg/I)
5
5
6
Hawaii MCLs'
(ma/1)
5
SDWAMCLGsr
(mg/1)
0
0
TBC Guidance0
Health
Advisories8
(mjs/1)
lh
3h
2-Butanone (methyl ethyl ketone)
Carbon disulfide
Carbon tetrachloride 5
Chlorome thane
1.1-Dichloroethane
1.2-Dichloroethane 5
cis-1.2-Dichloroethene 70
trans-1.2-Dichloroethene 200
Ethylbenzene 700
2-Hexanone
4-Methyl-l-pentanone
4-Methyl-2-pentanone
Methylene chloride 5
Nitrobenzene
Phenol
Pyrene
1.1.2.2-Tetrachloroethane
Tetrachloroethene 5
Toluene 1.000
Trichloroethene 5
Vinyl chloride 2
Xylenes, total 10.000
5
70
100
700
5
1.000
5
2
10,000
0
0
0
700
0
1,000
0
0
20,000
0.3n
0.4"
700
5h
4,000
0.7"
1,000
3h
10,000
Source: United States Army Environmental Center
ARARs Applicable or relevant and appropriate requirements
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act
CFR Code of Federal Regulations
EPA U.S. Environmental Protection Agency
HA Health advisory
MCL Maximum contaminant level
MCLG Maximum contaminant level goal
mg/1 Miligrams per liter
SDWA Safe Drinking Water Act
TBC To be considered
USAEC U.S. Army Environmental Center
a. This table provides ARARs or TBC guidance for all chemicals detected in the groundwater at Schofield
Barracks, as reported in Figure 3.5 of the Draft Final Sampling and Analysis Plan for Operable Unit 4 Phase II
Remedial Investigation and Feasibility Study Field Program. August 19.1994. The bolded and italicized
values indicate the ARAR or TBC for each chemical. The MCLs/MCLGs in this table are relevant and
appropriate requirements for cleanup of extracted groundwater. The MCLs would be applicable "at the tap.'
These decisions are based on the determination that the underground water system at Schofield Army
Barracks is a public water system designated as a Community Water System by the Hawaii Department of
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Table 2.3 (continued)
Health. Division of Drinking Water (Personal communication with A. Zane, Engineer. Division of Drinking
Water, July 25,1995). A Community Water System is "a public water system which serves at least 15
connections used by year-round residents or regularly .serves at least 25 year-round residents." (40 CFR §
141.2 Definitions [1994] and Hawaii Administrative Rules 20 § 11-20-2 Definitions [1994]).
b. Relevant and appropriate requirements are "those cleanup standards, standards of control, and other
substantive requirements, criteria, or limitations promulgated under federal environmental or state
environmental or facility siting laws that while not 'applicable' to a hazardous substance, pollutant,
contaminant, remedial action, location, or other circumstance at a CERCLA site, address problems or
situations sufficiently similar to those encountered at the CERCLA site that their use is well suited to the
particular site." (40 CFR § 300.5 Definitions. [1994]). "Maximum contaminant level goals (MCLGs).
established under the Safe Drinking Water Act. that are set at levels above zero, shall be attained by remedial
actions for ground waters that are current or potential sources of drinking water, where the MCLGs are
relevant and appropriate under the circumstances of release.* (40 CFR § 300.430[e][2][i)[6] [1994]).
c. This "category consists of advisories, criteria, or guidance that were developed by the EPA. other federal
agencies, or states that may be useful in developing CERCLA remedies.* (40 CFR § 300.400[g][3] [1994]).
TBCs are nonpromulgated advisories and are not legally binding. They "do not have the status of potential
ARARs.* (CERCLA Compliance with Other Laws Manual Draft Guidance. USEPA OSWER Directive 9234.1-
01.1968.)
d. 40 CFR Part 141 Subpart B and Subpart G (1994).
e. State of Hawaii Maximum Contamination Levels. Rules Relating to Potable Water Systems Title 11 Chapter
20 §§ 11-20-2, -3. and -4. as amended, originally effective August 6,1977. as Chapter 49 of the Public Health
Regulations, Department of Health.
f. 40 CFR Part 141 Subpart F (1994).
g. USEPA Office of Water Lifetime Health Advisories (HAs) for a 70-kg Adult, May 1995.
h. USEPA Office of Water Health Advisory representing a 1 x 10* cancer risk, the concentration in drinking
water that will result in one excess cancer death in one million people (May 1995).
i. Under review. Drinking Water Regulations and Health Advisories. USEPA Office of Water, May 1995.
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Table 2.4: Action-specific Applicable or Relevant and Appropriate Requirements
for OU 2 at Schofleld Army Barracks, Hawaii
Actions
Requirements
Prerequisite*
Federal Citation
Hawaii Citation
Alternative 1 No Action
Institutional controls
Instltnllonnl controls such as writer use and deed restrictions to
supplement engineering controls AS npproprlnte for short- and
long-term management to prevent or limit exposure to
linznrdons substances, pollutants, or contaminants.
Presence of hazardous
substances, pollutants.
or contnmlnnnts.
40 CFR §
300.430(ft)(l)(lll)(D)
to be considered.
Alternative 2 Air Stripping
Fugitive dust emissions
Visible fugitive dust emissions must not be discharged beyond
the property lot line on which the fugitive dust originates.
Reasonable precautions must be used to proven! fugitive dust
emissions.
Fugitive emissions
from excavation of
contaminated soil and
construction of pads.
§ll-eo.1-33(a)(l)
through (7) and (b)
applicable
Air emissions from the air stripper
Administrative and substantive requirements of permit If
exemption listed at §ll-60.1-02(d)(l) cannot be met.
Requirements Include the Installation of devices for the
measurement or analysis of source emissions or ambient
concentrations of air pollutants; monitoring; and requirements
concerning the use, maintenance, and Installation of
monitoring equipment.
Exemption under §11*
60.1-62(d)(l) cannot
be met. '
Sll-60.1-08
applicable
Discharge of treated groundwater
Comply with MCLs. See Section 3 of the OU 2 FS Report fora
discussion of MCLs.
Discharge of treated
groundwaler Into
water distribution
system.
335371
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Table 2.4 (continued)
Actions
Requirements
Prerequisites
Federal Citation Hawaii Citation
Alternative 4 Peroxide/Ozone Oxidation
Fugitive dust emissions Sea Alternative 2
Discharge of (rented groniidwnler See Alternative 2
CFR Code of Federal Regulations
MCL Maximum contaminant level
RCRA Resource Conservation and Recovery Act
UV Ultraviolet
33S;i707.ni.OO
(111.1003091) KOD
2«I2
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Table 2.5: Preliminary Estimated Influent Chemicals of Concern Concentrations
and Proposed Treatment Standards for Schofield Army Barracks OU 2
Estimated Range
of Groundwater
Influent Federal
Concentrations MCLs*
Chemicals of Concern frtg/1) frg/1)
Carbon tetrachloride <1b to 8.2b 5
Trichloroethene
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Table 2.6: Summary of Comparative Analysis of Alternatives
Evaluation Criteria
Alternative 1
No Action
Alternative 2
Groundwater Extraction, Air Stripping
Alternative 4
Groundwater Extraction, Ozone/Hydrogen
Peroxide Oxidation
Effectiveness
Overall protection of human
health and the environment
Inadequate; uncertainty regarding time
frame when OU 2 groimdwnter plume
would migrate offsite and what the TCE
concentration would be. Natural
attenuation will be the primary mechanism
for reducing contaminant concentration in
the aquifer.
Protective; Immediately upon treatment and
prior to distribution of the OU 2 groundwater
for domestic use. Natural attenuation will be
the primary mechanism for contaminant
concentration reduction in the aquifer.
Protective; immediately upon treatment and
prior to distribution of the OU 2 groundwater.
Natural attenuation will be the primary
mechanism for contaminant concentration
reduction In the aquifer.
Compliance with ARARs
and other guidance
No action does not achieve chemical-
specific ARARs, however, through natural
attenuation chemical-specific ARARs are
expected to be achieved; there are no
action-specific ARARs and no location-
specific ARARs.
Air stripping can meet chemical-specific
ARARs immediately through treatment at the
wellhead, and with time through natural
attenuation. However, because the alternative
will not actively restore the aquifer to below
MCL concentrations, a TI waiver has been
invoked for this ARAR. Action-specific and
location-specific ARARs are expected to be
met by this alternative.
Ozone/hydrogen peroxide oxidation can meet
chemical-specific ARARs immediately
through treatment at the wellhead, and with
time through natural attenuation. However,
because the alternative will not actively
restore the aquifer to below MCL
concentrations, a TI waiver has been invoked
for this ARAR. Action-specific and location-
specific ARARs are expected to be met by this
alternative.
Long-term effectiveness
Through deed restriction this alternative
will reduce residual risk associated with
the groundwater within the OU 2 plume
onsite. Future hypothetical risk and
exposure pathways would continue to pose
a threat to human health and the
environment. Natural attenuation will
eventually contribute to the attainment of
MCLs and the elimination of residual risk
and threat to human health and the
environment.
Treatment at the wellhead combined with
natural attenuation will eventually contribute
to the attainment of MCLs and the
elimination of residual risk and threat to
human health and the environment.
Treatment at the wellhead combined with
natural attenuation will eventually contribute
to the attainment of MCLs and the elimination
of residual risk and threat to human health
and the environment.
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Table 2.6 (continued)
Evaluation Criteria
Alternative 1
No Action
Alternative 2
Groundwaler Extraction, Air Stripping
Alternative 4
Groundwater Extraction, Ozone/Hydrogen
Peroxide Oxidation
Reduction of toxicity,
mobility, and volume
No reduction in mobility, toxicity, or
volume from treatment. However,
reduction in toxicity, mobility, and volume
through natural attenuation and
degradation.
Extracted groundwater will have a reduction
in toxicity and volume providing protection
to human health and the environment.
However, reduction in mobility, toxicity, and
volume will not occur to a large extent in the
contaminated groundwater system, except
through natural attenuation.
Contaminants In extracted groundwater will
be reduced in toxicity and volume providing
protection to human health and the
environment. However, reduction in
mobility, toxicity, and volume will not occur
in the contaminated groundwater system,
except through natural attenuation.
Short-term effectiveness
Unchanged; Army controls access to the
site and groundwater removal and use.
Impacts to the community and workers will
be minimal during construction of the
concrete pad and set up of the treatment
equipment. Possible short-term ecological
and environmental effects due to construction
activities from dust generation, vegetation
clearing, and constniction noise.
Impacts to the community and workers will
be minimal during constniction of the
concrete pad and set up of the treatment
equipment. Possible start-term ecological
and environmental effects due to constniction
activities from dust generation, vegetation
clearing, and constniction noise.
Implementability
Technically feasible to implement
groundwater monitoring program.
Technically feasible to implement.
Conventional equipment used in this
alternative. Effectiveness monitored through
process monitoring and groundwater
monitoring.
Technically feasible to implement.
Conventional equipment used in this
alternative. Effectiveness monitored through
process monitoring and groundwater
monitoring.
Cost
33537 07.04 "O
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Total Estimated Capital Cost = $0
Total Estimated Annual Operation and
Maintenance Cost = $87,500
Total Estimated Present Worth =
$1,350.000
Operating Flow Rate = 3,000 gpm
Total Estimated Capital Cost = $650,000
Total Estimated Annual Operation and
Maintenance Cost = $217,000
Operating Flow Rate = 3,000 gpm
Total Estimated Capital Cost = $1,500,000
Total Estimated Annual Operation and
Maintenance Cost = $287,000
Total Estimated Present Worth = $3,990,000 Total Estimated Present Worth = $5,910,000
2 of 3
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Table 2.6 (continued)
ARAR Applicable or relevnnt and appropriate requirement
gpm Gallons per minute
OU Operable unit
PRG Preliminary remediation goal
TCE Trichloroethene
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Table 2.7: Calculations for Estimated Maximum Trlchloroethene Vapor Discharge from
Alternative 2 (Air Stripping Treatment)
Assumptions:
• Maximum influent groundwater flow rate into the air stripper is 1,500 gallons per minute (gpm)
• The trichloroethene (TCE) concentration of 25 micrograms per liter (ug/1) is based on influent concentration data to the Schofield
Barracks water supply well air stripper treatment system.
Trichloroethene (TCE)
( 1 gram ^ ( 1 pound "j ( 3.785liters! f 60minutes \ f 1.500gallons^ ^.025milligrams"] ( 24 hour^ f 365day'j
U,000milligrams/Us3.8gramsJ I gallon J U,000milligrams/v minute ) (. liter )\ day )\ year )
= 164 pounds per year of TCE.
ROD
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Table 2.8: Summary of Estimated Costs for Remedial Action Alternatives
at Schofield Army Barracks for OU 2
Alternative 1:
Alternative 2:
Alternative 4:
Alternative
No Action
Air Stripping
Ozone/Hydrogen Peroxide Oxidation
Estimated
-Capital
Cost
($)
0
650,000
1.500.000
Estimated
Annual
O&MCost
ft)
87.500
217.000
287.000
Estimated
Net Present
Worth*
($)
1,350,000
3.990,000
5.910,000
O&M Operation and maintenance
* Based on 5 percent rate of return and 30-year life.
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Table 2.9: Estimated Cost Summary of Selected Remedy • Air Stripping
Capital Cost
Direct Capital Cost
Extraction system $19,000
Mobilization and demobilization/site work 41,000
Groundwater treatment system 322.000
Subtotal • Estimated Direct Capital Cost $382,000
Indirect Capital Cost
Contingency (@ 25 percent) $96,000
Engineering (@ 10 percent) 38,000
Contractor markup (@ 10 percent) 38,000
Construction management (@ 25 percent) 96.000
Total - Estimated Capital Cost $650.000
Annual Operation and Maintenance (O&M) Cost
Labor and maintenance $21,000
Electricity 83,000
Five-year site review and groundwater monitoring • 70.000
Subtotal - Estimated O&M Cost $174,000
Contingency (@ 25 percent) 43.000
Total Estimated Annual O&M Cost $217.000
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Pacific Ocean
SchofieM
Army Barracks
• East Range
B
Schofield x
Army Barracks
Main Post
Explanation
Boundary between groundwater bodies
JH Scnofield Army Barracks
Basal Water Body
Schofield High-tevel Water Body
Dikenrnpounded Water Body
KXNJ Groundwater dam
i , Generalized cross section line
Scale
10
Miles
Note: Modified from Dale and Takasakl. 1976
and Mink and Lau. 1987
Cross sections are shown in Figure 2.5.
larding Lawson Accociaas
ftQMM9IU1Q And
nvnonmantal SWVK«S
Prepared for:
U.S. Army Environmental Center
Aberdeen Proving Ground, Maryland
Schc field Army Barracks,
Island of Oah-j, Hawaii
Figure 2.1
Regional Groundwater Systems
cf Oahu, Hawaii
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I
c
I
UJ
Harding Liwton AttocltUt
frvjiiinoiirig and
lal Services
Walalua
Basal Water
Body
_\
Honolulu-Peart Harbor
Basal Water Body
B
Walahole Transmission
Tunnel
Explanation
Low-permeabllHy rock
Fresh groundwatar
Saline groundwaler
Groundwater flow line
(generalized direction)
Scale
3
Miles Nols: Cross-section lines are shown In Figure 2.4.
Modified from Dale and Takasakl, 1976
Prepared (or:
U.S. Army Environmental Center
Aberdeen Proving Ground, Maryland
Schofleld Army Barracks,
Island of Oahu, Hawaii
Figure 2.2
Regional Hydrogeologlc Cross Sections
A-A' and B-B'
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Schofltld Army Barracks
fe>-.
Schodsld Army Btrrackt
Forett Reserve
SchoMM Aimy B«'«tl»
Pitpnd lor
US KIMIEnvHonminUIC«nMi
AbtttfHA Plovlne Oiountf. U«yl»ld
-------
Si ti. >li<-l.| H*|fi ti-ift VV.tliM O.i.|v
Pf Rfwed lot
US Anny Environmental Ccntof
AU'iilrnn PfuvNtq Ground. M.irylaitd
St;tiolhirracks.
Island ol Oaliii. Hawaii
Pfnpnspfl Lnng-Teim
MotuioiingNoiworh
-------
Discharge to
Atmosphere
t
en
Extracted
Groundwater
Pump
Air Stripper
Treated Water to BWS
Distribution System
Blower
t
Disposal to
Nonhazardous Landfill
Explanation
-*• Liquid stream
•*• Air stream
1 — — — -^ Nonhazardous disposal
BWS Board of water supply
Harding Lawson Associates
Engineering and
Environmental Services
HLA
Prepared for:
U.S. Army Environmental Center
Aberdeen Proving Ground. Maryland
Schofield Army Barracks,
Island of Oahu, Hawaii
Figure 2.5
Alternative 2 Process Flow Diagram of Air
Stripping OU2 Groundwater Treatment
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Ozone
Generator
Explanation
•*• Liquid stream
1 — *• Air stream
' •- ^ Nonhazardous disposal
BWS Board of water supply
Extracted
Groundwater
Pump
Catalytic Ozone
Decomposer
Treated Air
„ Stream
Discharge
to Atmosphere
Ozone/Hydrogen
Peroxide
Oxidation
Disposal to
Nonhazardous Landfill
Treated Water to BWS
Distribution System
Harding Lawson Associates
Engineering and
Environmental Services
HLA
Prepared for:
U.S. Army Environmental Center
Aberdeen Proving Ground, Maryland
Schofield Army Barracks.
Island of Oahu, Hawaii
Figure 2.6
Alternative 4 Process Flow Diagram of
Ozone/Hydrogen Peroxide Oxidation
System for OU2 Groundwater
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3.0 RESPONSIVENESS SUMMARY
3.1 Overview
This section provides a summary of the public comments and concerns regarding the Proposed Plan at
Schofield Barracks, Island of Oahu, Hawaii. At the time of the public review period, the Army had
selected Alternative 2, as the preferred alternative for the OU 2 groundwater. On the basis of the
written and verbal comments received, the Army's Proposed Plan was generally accepted by the public.
3.2 Background on Community Involvement
The Army has implemented a progressive public relations and involvement program for environmental
activities at Schofield Barracks. A Technical Review Committee, comprised of representatives from the
Army, the EPA, the State of Hawaii DOH, and members of the general public, has been established and
meets periodically to involve the public in decisions made regarding investigation results, proposed
work, and potential remedial actions. The Army distributed over 100 copies of a fact sheet to interested
parties and to the information repositories (Section 2.6). These fact sheets described the installation
restoration program at Schofield Barracks, including a discussion of how the public could get more
information and get involved in the program. A synopsis of community relations activities conducted
by the Army is presented in Appendix A.
The Army held a public comment period on the alternatives presented in the OU 2 FS and Proposed
Plan from May 24 through June 24,1996. Over 100 copies of the Proposed Plan were mailed to the
public for review and comment and were placed in the repositories discussed in Section 2.6. The
Proposed Plan also invited readers to a public meeting to discuss the preferred alternative. This public
meeting was held to discuss the selected preferred alternative. The meeting was held on June 12, 1996,
from 7:00 to 8:00 p.m. in the Hale Koa, at Wahiawa District Park, 1139A Kilani Avenue, Wahiawa,
Hawaii.
Comments were received from the public regarding the Proposed Plan public during the comment
period and those comments are addressed below.
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Responsiveness Summary
3.3 Summary of Comments Received During Public Comment Period and
Department of the Army Responses
The comments received during the public comment period and accompanying Army responses are
provided in Appendix B.
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4.0 ACRONYMS
ARAR
Army
bgs
BWS
CERCLA
CFR
COC
COPC
CWA
DERP
DOD
DOH
DOI
EPA
ERA
ESPS
FWS
FFA
gpm
HAR
HC
HI
HLA
HRA
EPR
IRP
Applicable or relevant and appropriate requirement
U.S. Department of the Army
Below ground surface
Board of Water Supply
Comprehensive Environmental Response, Compensation, and Liability
Act
Code of Federal Regulations
Contaminants of concern
Chemicals of potential concern
Clean Water Act
Defense Environmental Restoration Program
U.S. Department of Defense
Department of Health
Department of Interior
U.S. Environmental Protection Agency
Ecological risk assessment
Environmental Services Program Support
U.S. Fish and Wildlife Service
Federal Facility Agreement
Gallons per minute
Hawaii Administrative Rules
Hawaii Citation
Hazard index
Harding Lawson Associates
Health risk assessment
In-Progress Review
Installation Restoration Program
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Acronyms
Ib/day
MCL
MCLG
NCP
NGVD
NMFS
NPL
O&M
OU
PA/SI
ppb
PRG
RCRA
RI/FS
RME
ROD
SAP
SARA
Schofield Barracks
SDWA
TBC
TCE
USAEC
use
uv
voc
WES
Pounds per day
Maximum Contaminant Level
Maximum contaminant level goal
National Oil and Hazardous Substances Pollution Contingency Plan
National Geodetic Vertical Datum of 1929
National Marine Fisheries Service
National Priorities List
Operation and maintenance
Operable unit
Preliminary Assessment/Site Investigation
Parts per billion
Preliminary remediation goal
Resource Conservation and Recovery Act
Remedial Investigation/Feasibility Study
Reasonable maximum exposure
Record of Decision
Sampling and Analysis Plan
Superfund Amendments and Reauthorization Act of 1986
Schofield Army Barracks
Safe Drinking Water Act
To be considered
Trichloroethene
U.S. Army Environmental Center
United States Code
Ultraviolet
Volatile organic compound
Waterways Experiment Station
4-2
Harding Lawson Associates
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Acronyms
Wheeler Wheeler Anny Airfield
WWH World Warn
jig/m3 Micrograms per cubic meter
/xg/1 Micrograms per liter
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5.0 REFERENCES
Dale, R.K., and K.J. Takasaki. 1976. Probable effects of increasing pumpage from the Schqfield
Groundwater Body, Island ofOahu, Hawaii. U.S. Geological Survey Water - Resources Investigations
76-47. Prepared in cooperation with the Board of Water Supply, City and County of Honolulu, Hawaii,
May.
Giambelluca, T.W., M.A. Nullet, and T.A. Schroeder. 1986. Rainfall atlas of Hawaii. Report No. R76.
Water Resources Research Center, University of Hawaii, June.
Harding Lawson Associates. 1992a. Final preliminaiy assessment/site investigation report for operable
units l, 2, and 4, Schofield Army Barracks, Island ofOahu, Hawaii, May 14.
. 1992b. Final work plan for the Schofield Barracks remedial investigation/feasibility study,
October 15.
. 1993. Final sampling and analysis plan for operable unit 2 phase I remedial investigation,
Schofield Army Barracks, Island of Oahu, Hawaii.
' . 1995a. Final sampling and analysis plan for operable unit 4 phase n remedial investigation and
feasibility study field program, Schofield Army Barracks, Island of Oahu, Hawaii, March 16.
. 1995b. Final remedial investigation report for operable unit 1, Schofield Army Barracks, Island
ofOahu, Hawaii, April.
. 1995c. Final sampling and analysis plan for operable unit 2 phase n remedial investigation,
Schofield Army Barracks, Island of Oahu, Hawaii, April.
. 1996a. Final feasibility study report for operable unit 2, Schofield Army Barracks, Island of
Oahu, Hawaii, May.
. 1996b. Draft Final operable unit 2 remedial investigation report, Schofield Army Barracks, May.
Mink, J. F.. and S. L. Lau. 1987. Aquifer identification and classification for Oahu: Groundwater
protection strategy for Hawaii. Technical Report No. 179. Water Resources Research Center, University
of Hawaii, November.
R.M Towill Corporation. 1977. Analysis of existing facilities, Schofield Barracks: U.S. Army Corps of
Engineers, Pacific Ocean Division, December.
U.S. Army Pacific Environmental Health Engineering Agency. 1977. Water quatity engineering special
study (W2J no. 94-001-77, surface-water study in support of environmental impact statement for
U.S. Army Support Command, Hawaii, Oahu, Hawaii. Phase Two, March 10 - April 22.
U.S. Army Support Command, Hawaii. 1983. Secretary of the Army environment quality award.
Personal communication with Harding Lawson Associates.
U.S. Environmental Protection Agency. 1993. Presumptive Remedy for CERCLA Municipal T^nHfil]
Sites, September.
. 1995. Region Kpreliminary remediation goals (PRGs), first half 1995; February 1.
U.S. Environmental Protection Agency (Region DC), The State of Hawaii, and the U.S. Department of the
Army. 1991. Schofield Barracks federal facility agreement, August.
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Appendix A
SYNOPSIS OF COMMUNITY RELATIONS ACTIVITIES
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Appendix A
May 1985 - Schofield Barracks issued a press release regarding the detection of Trichloroethylene (TCE)
in the Schofield Barracks Supply wells and the temporary switch to city and county water supplies.
August 1990 • Schofield Barracks issued a press release regarding the placement of the installation on
the National Priorities List (NPL).
October 1990 - Schofield Barracks Public Affairs Office and Environmental Office addressed the
Wahiawa Neighborhood Board regarding Army plans to conduct investigations on Schofield Barracks to
identify sources of TCE.
*•
January 1992 - Schofield Barracks and U.S. Army Toxic and Hazardous Materials Agency
(USATHAMA) submitted press releases requesting public involvement in locating the source(s) of TCE
contamination in and around Schofield Barracks.
January 1992 • Schofield Barracks and USATHAMA conducted interviews with twenty local residents
to assist in the development of a Community Relations Plan for the Schofield Barracks Installation
Restoration Program (IRP).
June 1992 - The Army finalized the Community Relations Plan for Schofield Barracks and placed copies
in the newly established information repositories located in the Milliard Public Library, the Wahiawa
Public Library, The Hawaii Department of Health, and the Directorate of Public Works in Building 300
of Wheeler Army Airfield.
February 25,1993 - Schofield Barracks and the Army Environmental Center (AEC) conducted a public
meeting at the Hale Koa at Wahiawa District Park in Wahiawa to provide the public with an update on
the IRP and the results of the first phase of the investigations.
February 1993 - In conjunction with the public meeting, the Army published and distributed a fact
sheet that provided an update on the IRP and initial investigative results.
September 13 and 14,1994 - Schofield Barracks and the AEC conducted public availability sessions at
the Hale Koa at Wahiawa District Park (September 13) and at the Schofield Barracks Post Library
(September 14) to provide an update on the IRP.
September 13 and 14,1994 - In conjunction with the public availability sessions, the Army solicited
interest in the formation of a Restoration Advisory Board (RAB) comprised of local citizen representa-
tives, Army representatives, and regulatory agency representatives that would oversee the conduct of
the Army's IRP at Schofield Barracks.
September 12 through 14,1994 - The Army presented a poster display that summarized installation
restoration efforts and plans for Schofield Barracks at the 1st Hawaii National Technologies Conference
sponsored by the Hawaii Department of Health
September 1994 - In conjunction with the public availability session, the Army published and
distributed a fact sheet that provided an update on the IRP and initial investigative results.
May 24 throughjune 24.1996 - Schofield Barracks conducted a public review period for the Proposed
Plan for Operable Unit 2.
June 12,1996 - Schofield Barracks and the AEC conducted a public meeting to present the Operable
Unit 2 Proposed Plan and solicit public comments.
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Appendix B
COMMEKTS RECEIVED DURING PUBLIC COMMENT PERIOD AND ARMY RESPONSES
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Directorate of Public Works - MS 0 9
Mr. Henry Curtis
Executive Director
Life of the Land
1111 Bishop Street
Suite 503
Honolulu, Hawaii 96813
Dear Mr. Curtis:
Thank you for your input on the Army's Proposed Plan for addressing ground water contamination at
Schofield Barracks.
In response to your comment regarding the detection levels used in monitoring water supply wells
under the Schofield Barracks installation restoration program, the Army, in the past has used an
analytical method that will accurately detect trichloroethylene (TCE) down to 1.0 micrograms per liter
(ug/1) or parts per billion (ppb). This provides an adequate safety factor between the detection limits and
the Safe Drinking Water Act Maximum Contaminant Level of 5 ug/l. In addition, the Army recently
agreed to a request by the Hawaii Department of Health to use a drinking water analytical method that
will detect TCE down to 0.3 ug/1 for all future sampling to be conducted under the proposed wellhead
treatment remedial action.
We would like to assure you that the approach in the Operable Unit 2 Proposed Plan for addressing
the groundvvater contamination is fully protective of human health and the environment. The Army is
committed to ensuring that the water supply wells potentially impacted by the TCE originating from
Schofield Barracks are monitored and that actions are taken if TCE is found in those supply wells.
Your participation in the OU 2 Proposed Plan Public meeting was appreciated. Your continued
interest in the cleanup efforts at Schofield Barracks is encouraged, and if you have any further questions,
please contact Mr. Jon Fukuda, Environmental Department, Directorate of Public Works, 656-6790.
Sincerely,
Dennis J. Fontana
Colonel, U.S. Army
Director of Public Works
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LIFE OF THE LAND
HAW AITS OWN ENVIRONMENTAL ACTION GROUP
EDUCATION, RESEARCH, LOBBYING & LITIGATION
PROTECTING HAWAITS FRAGILE ENVIRONMENT
June 21, 1996
. Comments RE: Operable Unit 2: Ground water
The facts are simple. TCE exists in the groundwaier. The Army/EPA has spent $8M looking for the
source, unfortunately unsucessfully. The Army has removed an equivalent of I drum (55 gallons) of
TCE per year from groundwater filtration for the past 10 years.
The City & County of Honolulu's Board of Water Supply (BWS) maintains five separate water
systems for Oaliu. They are:
Waialua—Haleiwa-Sunset;
Waianae—Ewa—Downtown-East Honolulu—Windward
Wahiawa;
Mililani;
• Kunia.
The fiction is that everything is okay. The BWS has monitored wells for pesticide and toxic
contamination for many years. Persistent critics outside of the government, and sources within the
BWS have slated that the BWS tests leave a lot to be desired. If contamination is found in a well,
either the detection level for a test will be lowered (if 3 ppb was detected, the next testing will only be
able to measure 5 ppb), or the well will no longer he tested.
There is a disease cluster in Village Park. Many believe that the contamination is in the ground water
or the soil. The Hawaii Department of Health has testified before the State Legislature that they would
investigate — if the had the $ — but since they don't — other priorites come first.
The EPA came out to Oahu last fall to obtain information about the proposed Kunia Superfund
site.The EPA asked Life of the Land for input. The EPA wanted to limit the Kunia.Superfund to
Kunia. The EPA did not want the Proposed Kunia Superfund Sue to overlap with the Schofield
Superfund Site. Too many complications!
The GaJbraith property has been proposed as the site for the joint VVahiawa/Schofield Wastewatei
Treatment Plant and Wetlands Facility. This would require separating the Schofield Superfund Site
into sections, and (hen de-listing the Galbraiih section.
These examples lead the environmental community 10 question the message we are receiving.
1111 Bishop St, Suite 503 • Honolulu, HI 96813 • 533-3454 • fax 533-0993
-------
In this case, the community, through participation in the RAB process, can feel assurred that
everything is under control. The community would also feel comfortable knowing that if conditions
change, they would know about the changes up-front. The military could also profit greatly from this
continued interaction with the community.
Life of the Land is interesting in serving on such a Board.
Henry Q Curiis
Executive Director
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O'AHU GROUP
SIERRA CLUB/HAWAI'I CHAPTER
P.O. Box 2577, Honolulu, Hawaii 96803
Phone:(808)538-6616
June 18, 1996
Commander
USAG-HI
Directorate of Public Works
Attn: Mr. John Fukuda
Schofield Barracks HI 96857-5000
Dear Mr. Fukuda/
The Oxahu Group of the Sierra Club is concerned that the
proposed plan to address groundwater contamination at Schofield
does not appear to call for the long-term cleanup of site
contamination and restoration of the groundwater system. While
it may be cost-effective in the short-term to treat water before
consumption, it is imperative that the sources of contamination
be identified and cleaned up. .
Sincerely,
PHILIP D. BOG
Oahu Group Chair,
Hawaii Chapter,
Sierra Club
100% Recycled Paper
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Directorate of Public Works - !:"[1
Mr. Phillip D. Bogetto
O'ahu Group Chair
Hawaii Chapter
Sierra Club
P.O. Box 2577
Honolulu, Hawaii 96803
Dear Mr. Bogetto:
Thank you for your input on the Army's Proposed Plan for addressing groundwater contamination at
Schofield Barracks.
The Army shares your opinion that the best approach for protecting and restoring groundwater is to
identify and cleanup sources of contamination. The Army's highest priority under the installation
restoration program was the identification and investigation of potential sources of the solvent
trichloroethylene (TCE) which resulted in contamination of the groundwater underlying the installation.
A thorough investigation was conducted under Operable Unit 1 (TCE sources) to determine the source,
or sources, of TCE contamination. The investigation included extensive historical records search,
interviews with past employees, an extensive review of historical aerial photographs and site walks to
identify potential source areas. This was followed by a remedial investigation of those sites which
included soil gas surveys to detect the smallest presence of TCE and other contaminants. Unfortunately,
that search failed to identify a source of contamination. As discussed at the Operable Unit 1 public
meeting on July 18, 1995, the Army has followed up on all information regarding possible TCE sources
and will continue to do so, however, at this time we have investigated all suspected sites.
We would like to assure you that the approach proposed under the Operable Unit 2 Proposed Plan is
fully protective of human health and the environment. The Army is committed to ensuring that the water
supply wells potentially impacted by the TCE originating from Schofield Barracks are monitored and
that actions are taken if TCE is found in the supply wells.
-------
-2-
Your continued interest in the cleanup efforts at Schofield Barracks is encouraged, and if you have
any questions, please contact Mr. Jon Fukuda, Environmental Department, Directorate'of Public Works
656-6790. '
Sincerely,
^ Dennis J. Fontana
Colonel, U.S. Army
Director of Public Works
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HOUSE OF REPRESENTATIVES
STATE OP HAWAII
STATE CAPITOL
Marcus R.Oshiro HONOLULU. HAWAII 96813 Dislricl 40
Slate Representative Wahiawa Whitmwe Village
June 20. 1996
Commander
U.S. Army Garrison - Hawaii
Directorate of Public Works
ATTN: APVG-GWV (Mr. Jon Fukuda)
Schofield Barracks. Hawaii 96857-5000
Dear Commander:
RE: OU2 Public Comments
Please accept the following as my written comments to the proposed clean up
plans for Operable Unit 2 (OU2). My concerns regarding the proposed
alternative are as follows:
1 Source of carbon tetrachloride and TCE has not been identified.
I have concerns regarding the integrity of the Risk Assessment; How can
one measure the risk of danger to health and environmental when there is
no knowledge of the extent of contamination? Do you have any best
estimates of the quantity of contamination? Can this be deduced from
past records, oral investigations of past personnel? More resources
should be directed to ascertaining the extent of and quantity of
contamination.
2 Protection of Public Water Supply.
I have grave concerns over the current monitoring process, especially
given the close proximity of Board of Water Supply wells and water
sources of the contaminated groundwater beneath Schofield. If the
contaminated body of groundwater should move from it present site,
would it not expose the public water supply to contamination also?
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OU2
June 20, 1996
Page 2
I would like clarification on the safeguards currently established.
Likewise, clarification of the safeguards being taken to insure that the
larger groundwater body is not contaminated.
I wish to obtain a copy of the map of the test sites and the corresponding levels
of contaminants found in each (This was the visual aid used at the Public
Meeting).
I thank you for the opportunity to comment. If you have any questions or if I can
be of any further assistance, please feel free to contact me at 586-8505.
Very truly yours.
MARCUS R. OSHIRO
State Representative
MO:gt
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DEPARTMENT OF THE ARMY
HEADQUARTERS. UNITED STATES ARMY GARRISON. HAWAII
SCHORELD BARRACKS, HAWAII 96857-5000
REPLY TO
ATTENTION OF
August 30, 1996
Directorate of Public Works
Honorable Marcus R. Oshiro
State Representative
District 40 -
State of Hawaii
State Capitol ' . . •*r
Honolulu, Hawaii 96813
Dear Mr. Oshiro:
I would like to thank you for the interest you have shown in the Army's clean-up program at
Schofield Barracks and for your .comments on the Operable Unit 2 (Groundwater) Proposed Plan
provided in your letter of June 20,1996. The following information is provided in response to your
comments:
Comment 1: Source of carbon tetrachloride and TCE has not been identified.
Response: The Army shares your concern that the source of the TCE plume from the East Range
Area has not been specifically identified. The Army's highest priority under the installation restoration
program was the identification and investigation of potential sources of the solvent trichloroethylene
(TCE), which resulted in contamination of the groundwater underlying the installation. The best
approach for protecting and restoring groundwater is to identify and clean up sources of contamination.
A thorough investigation was conducted under Operable Unit 1 (TCE Sources) to determine the source
or sources of TCE contamination. The investigation included extensive historical record searches,
interviews with over 120 people, an extensive review of historical aerial photographs (120 photographs
dating back to the 1940's), and site walks to identify potential source areas. This was followed by a
remedial investigation of those sites, which included soil gas surveys to detect the smallest presence of
TCE in the soils, soil sampling to depths of 150 feet, stream and sediment sampling, geophysical surveys
to locate past disposal trenches, and various other techniques to determine the presence of TCE and other
contaminants. Unfortunately, that search failed to identify a source of contamination. As discussed at
theOperable Unit I public meeting on July IS. 1995, the Army has followed up on all information
regarding possible TCE sources. However, at this time, we have investigated all suspected sites.
The risk assessment conducted for the groundwater contamination at Schofield Barracks was
performed using the highest concentration of TCE recorded in the groundwater at the East Range. These
levels are much higher than those currently found in the Schofield Supply wells, and are much higher
than could potentially migrate to other municipal water supply wells downgradient of Schofield
Barracks. Natural processes of dilution, absorption and degradation will continue to reduce TCE
concentrations as the groundwater moves away from ihe Schofield area.
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-2-
Even using the highest concentrations, the grouiidwater risk assessment showed no unacceptable risk
from consumption of the untreated groundwater. Regardless of the risk, the Army is obligated under
Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) to address
groundwater contamination based on the exceedance of Safe Drinking Water Act Maximum
Contaminant Levels (MCLs) under the Safe Drinking Water Act for TCE and carbon tetrachloride. The
proposed plan for Operable Unit 2 addresses the contamination through long-term monitoring of the
supply wells,
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Estimated
SeholhkJ Hlgh-lqvd Water Body
Piopoied Long-letm Giounflwnlci
Monilorioy Nolwoih
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Appendix C
ANALYSIS OF THE IMPACT OF TRICHLOROETHENE ON CARBON USAGE
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Appendix C
ANALYSIS OF THE IMPACT OF TRICHLOROETHENE (TOE) ON CARBON USAGE IN THE
HONOLULU BOARD OF WATER SUPPLY TREATMENT SYSTEMS
HLA contacted both Carbonaire and Calgon and asked each of the companies to model the possible
effects of TCE on the groundwater that is currently being treated at the Board of Water Supply's
Mililani I and Mililani n systems. Table 1 was provided to both companies. Both companies were
asked to model the effects of a range of TCE concentrations (0.5 micrograms per literfrig/l), 1.0 /ig/1,
2.0 ng/l, 3.0 Mg/l 5.0 Mg/1.10.0/ig/l. 15.0 /ig/1 and 25 jtg/1) on carbon usage if the treatment system
influent contained the highest contaminant concentrations listed for each chemical on Table 1 (3.0 ngfl
of 1,2,3-trichloropropane (TCP), 0.9 ng/l 1,2-Dichloropropane (DCP) and l,2-Dibromo-3-chloropropane
(DBCP)) and the TCE concentrations in the effluent were not to exceed 2.5 jig/1.
Carbonaire could not model a multicpmponent system where the least adsorbable compound (i.e., TCE)
was not the driver (compound driving the usage rate). However, Carbonaire estimated that TCE would
only have a minor affect on the adsorption of TCP. Calgon was able to model a multi-component
system using a proprietary program developed for Calgon. The program is based on Polyani Adsorption
Theory and incorporates the modification of the theory proposed by Hansen and Fackler. The theory
and equations were derived from the first principals of thermodynamics. The effects of competive
adsorption between the identified species are considered when determining the total capacity of the
GAC and the composition of the adsorbate mixture that fills the carbon.
The principals and assumptions incorporated into the model were given by Calgon as follows:
• All adsorbates gave equal access to all sites. This limits the model because molecular sieving
can exclude certain molecules because of size or shape.
• The possibility of chemisorption is not considered. ChemiSQiption generally occurs when
carbon acts as a catalyst causing a chemical reaction to occur when certain chemicals come into
contact with carbon . The compound that reacts with the carbon may then react with the
contaminant of concern that you are trying to remove from your water and change the
contaminant of concern in such a way that it will no longer adsorb to the carbon.
• The adsorbates compete for adsorption sites on a volume basis, so a large molecule displaces an
equal volume of small molecules.
33537 07.04.oo Harding Lawson Associates C-1
07188/30/96 ROD
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Appendix C
• The molecule having adsorption with the greatest thermodynamic driving force will displace or
prevent adsorption of other molecules at a specific site.
The modeling results from Calgon are presented in Table 2 to for Mililani I and Mililani ffl systems.
The modeling results indicate that the carbon usage rate will go up as the concentrations of TCE
increase from 0.5 Mg/1 to 5.0 /ig/1 indicating that the U.S. Army would be responsible for sharing some
carbon usage costs at concentrations ranging between the detection limit and 2.5 ngf\. However,
additional cost for carbon usage would not be high enough to warrant installation of the air stripper
prior to TCE concentrations reaching 2.5 /xg/1.
Harding Lawson Associates 33537 07.04.00
08308/30/96
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Table 1: Honolulu Board of Water Supply Chemical Laboratory Report
Subject*
Trihelomethanes/Volatile Organic Chemicals Test Results
Sample Source
Compound
Mililani
Wells 1
GAC Cent #11
Mililani
Wells 1
Pump #3
Mililani
Wells 1
Pump. #4
Detection
Limit
(MS/1)
EPA
MCL
(MS/1)
1,2-Dichloropropane (DCP) 0.9 0.7 0.8
1,2,3-Trichloropropane (TCP) 0.2 3.0 2.2
1,2-Dibromo 3-Chrloropropane <0.01 0.10 0.14
(DBCP)
1,2-Dibromethane (EDB) <0.0l <0.0l <0.01
Date Sampled: 10/18/95 10/17/95 10/17/95
Date Received: 10/20/95 10/20/95 10/20/95
Date Analyzed: 10/25,26/95 10/25/95 10/25/95
Lab ID No.: 951020028 951020021 951020022
0.1
0.1
0.01
0.01
3
0.8*
0.04'
0.04 *
State DOH MCL
28339 07.04.00
07188/23/96 CEA
Harding Lawson Associates
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Table 2: Estimated Increase in Cartoon Usage at Mililani I and Mililani II Systems
TCE
Influent
fctt/1)
Mililanil
0.5
1
2
3
5
10
15
25
Mililanfll
0,5
1
2
3
5
10
15
25
TCE
Effluent
tttg/I)
0.5
1
2
2.5
2.5
2.5
2.5
2.5
0.5
1
2
2.5
2.5
2.5
2.5
2.5
Estimated
Annual
Carbon, Usage*
flba/yr)
240,000
240,000
240,000
240,000
240,000
240,000
240,000
240,000
80,000
80,000
80,000
80,000
80,000
80,000
80,000
80,000
Percent Increase
of Annual
Carfaonb
Usage Rate
<1
4
8
12
23
46
62
96
<1
4
8
12
23
46
62
96
Carbon
Replacement
and Disposal Cost*
r$/ib)
$1.70
$1.70
$1.70
$1.70
$1.70
$1.70
$1.70
$1.70
$1.70
$1.70
$1.70
$1.70
$1.70
$1.70
$1.70
$1.70
Annual Increase in
Carbon
Replacement
and Disposal Cost
Approx $4,100.00
$16,320.00
$32,960.00
$48,960.00
$93,840.00
$187,680.00
$252.960.00
$391,680.00
Approx.$l, 400.00
$5,440.00
$10,880.00
$16,320.00
$31,280.00
$62,560.00
$84,320.00
$130,560.00
a. Estimated annual carbon usage rates and carbon replacement and disposal cost were provided by Honolulu Board
of Water Supply.
b. Percent increase of annual carbon usage rate if TCE impacts B WS carbon treatment system was provided by Calgon
using their proprietary multicomponent computer model.
28339 07.04.00
. 07188/30/96 CEA
Harding Lawson Associates
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