PB96-964512
EPA/ROD/R09-96/155
December 1996
EPA Superfund
Record of Decision:
Schofield Barracks (U.S. Army),
Operable Unit 4, Oahu, HI
9/26/1996
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Final Record of Decision
for Operable Unit 4
Schofield Army Barracks
Island of Oahu, Hawaii
Prepared for
U.S. Army Environmental Center
Installation Restoration Division
HLA Project No. 28339 14.03.00
Contract DAAA15-91-D-0013
Delivery Order No. DA03
THIS DOCUMENT IS INTENDED TO COMPLY WITH THE NATIONAL
ENVIRONMENTAL POLICY ACT OF 1969.
THE USE OF TRADE NAMES IN THIS REPORT DOES NOT CONSTITUTE AN
OFFICIAL ENDORSEMENT OR APPROVAL OF THE USE OF SUCH COMMERCIAL
PRODUCTS. THE REPORT MAY NOT BE CITED FOR PURPOSES OF
ADVERTISEMENT.
July 12,1996
Harding Lawson Associates
Engineering and Environmental Services 235 Pearlridge Center Phase I
707 Seventeenth Street, Suite 2400 98-1005 Moanalua Road
Denver, CO 80202 - (303) 292-5365 Aiea, HI 96701 - (808) 486-6009
Recycled Paper
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Total Environmental Program Support
Final Record of Decision for Operable Unit 4
Schofield Army Barracks, Island of Oahu, Hawaii
July 12,1996
Contract Number DAAA15-91-D-0013
Delivery Order No. DA03
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 2-3
2.3 Enforcement and Regulatory History 2-3
2.4 Operable Unit 4 Site Selection History 2-4
2.5 Operable Unit 4 Site Description 2-5
2.5.1 Past Disposal Practices 2-5
2.5.2 Related Landfill Operations 2-7
2.6 Highlights of Community Participation 2-9
2.7 Scope and Role of Operable Unit 2-10
2.8 Site Characterization 2-11
2.8.1 Soil Gas 2-11
2.8.2 Surface Soil 2-12
2.8.3 Subsurface Soil 2-12
2.8.4 Surface Water and Sediment 2-13
2.8.5 Landfill Gas 2-14
2.8.6 Leachate... 2-14
2.8.7 Groundwater 2-15
2.8.8 Ambient Air 2-15
2.8.9 Summary of Site Characterization 2-15
2.9 Summary of Site Risks 2-16
2.10 Description of Alternatives 2-18
2.10.1 Alternative 1 - No Further Action/Institutional Controls 2-19
2.10.2 Alternative 2 - Maintenance of the Landfill Cover 2-21
2.10.3 Alternative 3 - Maintenance and Revegetation of the
Landfill Cover 2-24
2.10.4 Alternative 4 - Maintenance and Revegetation of the
Landfill Cover with Vapor Extraction 2-26
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2.11 Summary of Comparative Analysis of Alternatives 2-27
2.11.1 Overall Protection of Human Health and the Environment 2-27
2.11.2 Compliance with ARARs 2-28
2.11.3 Long-term Effectiveness and Permanence 2-28
2.11.4 Reduction in Toxicity, Mobility, and Volume 2-28
2.11.5 Short-term Effectiveness 2-29
2.11.6 Implementability 2-29
2.11.7 Cost 2-30
2.11.8 State Acceptance 2-30
2.11.9 Community Acceptance 2-30
2.12 Selected Remedy 2-30
2.13 Statutory Determinations 2-31
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 Chemicals of Potential Concern for OU 4
2.2 Summary of Total and Incremental Risks at OU 4 for Potentially Exposed Populations
2.3 Action-specific Applicable or Relevant and Appropriate Requirements for Alternatives 2, 3,
and 4 for Operable Unit 4 at Schofield Army Barracks, Hawaii
2.4 Target Compound List for Volatile Organic Compounds and Target Detection Levels for Water
Sample Analyses ,
2.5 Summary of Comparative Analysis of Alternatives
2.6 Estimated Capital Cost, Operation and Maintenance Cost, and Net Present Worth
2.7 Estimated Cost Summary of Selected Remedy - Regrade and Revegetate Landfill Cover
FIGURES
1.1 Location Map of Schofield Barracks
1.2 Site Map of Schofield Barracks
1.3 Location Map of Operable Unit 4 - Former T-anHfill
2.1 Regional Groundwater Systems of Oahu, Hawaii
2.2 Regional Hydrogeologic Cross Sections A-A' and B-B'
2.3 Pre-closure Landfill Features
2.4 Pre-closure Landfill Areas
2.5 Soil Gas TCE Concentrations Operable Unit 4
2.6 Boring, Lysimeter, Monitoring Well, and Surface-Water and Sediment Sampling Locations
Operable Unit 4
2.7 Conceptual Groundwater Monitoring Network
2.8 As-Built Drawing for Former Landfill Operable Unit 4
2.9 Plan View of Existing Cover on Former Landfill Operable Unit 4
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2.10 Location of Existing Gas Monitoring Wells Operable Unit 4
2.11 Conceptual Layout of Perimeter Landfill Gas Monitoring Wells Operable Unit 4
2.12 Location of Potential Hot Spot Operable Unit 4
2.13 Conceptual Layout of SVE System Operable Unit 4
APPENDIX
A SYNOPSIS OF COMMUNITY RELATIONS ACTIVITIES
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1.0 DECLARATION
I
This Final Record of Decision (ROD) for Operable Unit (OU) 4 has been prepared by Harding Lawson
Associates (HLA) for the U.S. Army Environmental Center (USAEC) under Delivery Order No. DA03 of
the Total Environmental Program Support (TEPS) Contract DAAA15-91-D-0013. This report
documents the response action plan for OU 4 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 an approximate total area of 27.7 square miles. Wheeler Army Airfield lies between
and to the south of the two Schofield Barracks sections.
The Schofield Barracks OU 4 consists of the Former Schofield Barracks Landfill (Former Landfill) on
the Main Post of Schofield Barracks (Figure 1.3).
1.2 Statement of Basis and Purpose
This decision document (ROD) presents a response action for OU 4, the Former Landfill. 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 4.
Information supporting the selected response action is contained in the Administrative Record for
Schofield Barracks. The U.S. Environmental Protection Agency (EPA) and the State of Hawaii concur
with the selected response action (remedy).
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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
This OU is one of four OUs for the site. The function of OU 4 is to address the Former Landfill The
remedy addresses the Former Landfill as a potential source of groundwater contamination and
reduces the potential risks associated with exposure to the contaminated landfill contents. OU 2
addresses the basewide groundwater contamination.
The following are major components of the selected remedy:
• Regrade existing landfill cover to generally match the 1983 engineered drainage grade
• Remove existing Guinea grass and revegetate with another type of grass that is more
appropriate for a landfill cover I
• Perform long-term maintenance of the landfill cover
• Maintain existing landfill gas venting
• Tnctall additional gas monitoring points at the perimeter of the landfill
• Implement institutional controls (groundwater monitoring, five-year site review, land-use
restrictions and site security)
1.5 Declaration Statement
The selected alternative is protective of human health and the environment, complies with federal
and State of Hawaii requirements that are legally applicable or relevant and appropriate to the
remedial action, and is cost effective. This action is a permanent solution to the maximum extent
practicable or necessary for OU 4 and is consistent with the EPA's Presumptive Remedy for CERQA
municipal landfills (EPA, 1993a). Because this action will result in hazardous substances (landfill
contents) remaining onsite exceeding acceptable health-based levels, a review will be conducted
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Declaration
within five years of commencement of the response action to ensure that the remedy continues to
provide adequate protection of human health and the environment
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Declaration
FRANK L. MILLER, JR.,
Major General, USA
Assistant Chief of Staff
for Installation Management
U.S. Army
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Declaration
Director, Federal Facilities Compliance Office
U.S. EPA, Region K
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Declaration
Lawrence Miike, M.D.
Director of Health
State of Hawaii
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Schofield
Barracks *
East Range
Kunia® /VRsWililani
/ W
H2
«
\ (99
Waipahu
Schofield
Barracks
Main Post
I
Honolulu
Explanation
Schofield Barracks
Cities, towns
. Rivers, streams
Highways, roads
Sources: U.S. Army Pacific Environmental Health
Engineering Agency (USAPEHEA), 1977.
642d Engineer Battalion fTOPO), 1977.
ESE, 1984.
Scale
5
10
Mites
10
Kilometers
Harding Lawson Associates
Engineering and
Environmental Services
Prepared for:
U.S. Army Environmental Center
Aberdeen Proving Ground, Maryland
Schofield Barracks, Island of Oahu, Hawaii
Figure 1.1
Location Map of Schofield Barracks
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Explanation
ScholwW Arniy Barrack! boundary
Forest reserve boundary
Road or street
Town
WhMMrArmyAirfWdbound«ry
Scrnlield Army BamAs
Steam or gulcn
. ^^f-^&^xSF^.
-•- -.,-K •*:~S,\'fs5£i
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_^ Former Landfill
^Operable Unit 4
Schof leld Army Barracks
Main Post
Schofield/Army v
Barracks
Forest Reserve
Kolekole
Pass
Explanation
Site boundary
Highway
Road or street
Town
- - - _ Wheeler Army Airfield boundary
Surface-water drainage, may be intermittent
I I Landfill
0 2000 4000
^^tsss
Scale in feet
Harding Lawson Associates
Prepared for:
U.S. Army Environmental Center
Aberdeen Proving Ground, Maryland
Engineering and
Environmental Sen/ices
Location Map of Operable Unit 4
Former Landfill
Schofield Army Barracks,
Island of Oahu, Hawaii
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2.0 DECISION SUMMARY
This section provides an overview of the site-specific factors and analyses that led to the selection of
the preferred alternative. This overview includes a general site description, site history, enforcement
and regulatory history, highlights of community participation, scope and role of OU 4, site character-
istics, 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), its contractors, and the EPA and has been previously presented
in more detail in the Preliminary Assessment/Site Investigation (PA/SI) Report (HLA, 1992a),
Remedial Investigation/Feasibility Study (RI/FS) Work Plan (HLA, 1992b), Final OU 4 Phase I
Sampling and Analysis Plan (SAP) (HLA, 1993), Final OU 4 Phase H SAP (HLA, 1995a), and the Final
Feasibility Study for Operable Unit 4 (HLA, 1995c).
2.1 Sehofiefd 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 approxi-
mately 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
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Decision Summary
inteibedded pahoehoe and a'a lava flows. The lava flows are highly fractured with cinder and clinker
zones.
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.
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2.2 Sehofield Barracks Installation Operational History
Scbofield 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 trailing facility during the
Korean and Vietnam conflicts. Since the Vietnam conflict, it has served primarily as a training
facility.
Sehofield 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
Trichloroethene [TCE), a commonly used cleaning solvent, was detected in the Sehofield 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 Sehofield
Barracks domestic water supply. In 1987, the EPA established a Maximum Contaminant Level (MCL)
for TCE of 5 parts per billion in drinking water. TCE has not been detected in Sehofield Barracks'
treated groundwater at concentrations greater than this EPA-established limit
As a result of the detection of TCE in the Sehofield Barracks water-supply wells, Sehofield Barracks
was placed on the National Priorities list (NPL) in August 1991. The NPL was developed by EPA to
identify sites that may present a risk to public health or the environment
After Sehofield Barracks was placed on the NPL, a Federal Facility Agreement (FFA) was negotiated
among the EPA, the State of Hawaii, and the Army under CERCLA, Section 120. The FFA was signed
by the Army on September 23,1991, and by the EPA on September 27,1991. Signature by the State
of Hawaii is still pending. The FFA identified Sehofield Barracks as being under the jurisdiction,
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Decision Summary
custody, or control of the U.S. Department of Defense (DOD) and subject to the Defense
Environmental Restoration Program (DERP).
2.4 Operable Unit 4 Site Selection History
As a part of the EPA, the Army and regulatory agencies agreed to divide the program into subunits
called OUs to address potential areas of contamination at Schon'eld Barracks in an organized manner.
This ROD addresses OU 4, which was established to investigate adverse impacts on ground-water,
surface water, soil, or air caused by the Former T-andfin.
During 1991, the Army began to investigate potential contaminant sources at Schon'eld 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 Schon'eld Barracks and the
surrounding study area. The PA consisted of the following three activities designed to collect
additional information regarding Schon'eld Barracks and nearby offpost communities:
• Conduct an onpost records search of 10 onpost sites (including the Former Landfill) identified
in the FFA (EPA and others, 1991).
• Survey and sample existing water-supply wells in the Schon'eld 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, an additional assessment was
recommended. An additional assessment was conducted as a part of the Phase IRI for the Former
landfill. The results of the Phase I RI were presented in the Final Phase n RI Sampling and Analysis
Plan (OU 4 Phase n SAP) (HLA, 1995a). The Final Phase n RI Sampling and Analysis Plan recom-
mended additional assessment work that included surface-water resampling, soil-gas sampling,
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analysis of landfill cap and slope integrity, and well Installation and sampling. As part of the Phase I
and n RI, monitoring wells in the vicinity of the Former Landfill were installed to obtain additional
information regarding groundwater flow and to collect groundwater samples from the Schofield High-
level Water Body near the Former Landfill. During Phase I and n Remedial Investigations, TCE was
detected in subsurface-soil samples, leachate samples, and groundwater samples, indicating that the
Former Landfill is a likely source of volatile organic compounds (VOCs) to groundwater beneath the
landfill
2.5 Operable Unit 4 Site Description
A description of past disposal practices, past landfill operations, and potential sources of contamina-
tion at OU 4 is provided below.
2.5.1 Past Disposal Practices
The Former I-a-nHfill was an open burn dump from approximately 1942 until 1967, when it was
converted to a sanitary landfill in response to provisions of the Clean Air Act (Ecology and Environ-
ment, Inc., 1981; Kennedy Engineers, 1980b). The Former landfill was used to dispose of a wide
variety of solid wastes from various military installations, of which the major contributors were
Schofield Barracks, Wheeler Air Force Base (currently Wheeler Army Airfield), and the Wahiawa
Radio Station (U.S. Army Support Command, Hawaii [USASCH], 1983; Kennedy Engineers, I980b).
Most of the waste deposited in the landfill was domestic refuse from the surrounding base housing
(Ecology and Environment, Inc., 1981); however, wastes were also disposed from various industrial
operations (e.g., vehicle and equipment maintenance and construction). Tripler Army Medical Center
(TAMC) reportedly contributed medical wastes including pathogenic, infectious, and pharmaceutical
(expired and unusable drugs) wastes (Ecology and Environment, Inc., 1981; Kennedy Engineers, Inc.,
1980b).
Other materials reportedly disposed in the Former Landfill were organic solvents, sewage sludge,
asbestos, pesticide containers, unusable paints, metallic debris, vegetation, and tree stumps
(Environmental Science and Engineering (ESE), 1984). Hazardous materials, including live munitions,
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acids, and solvents, were also reported to have been dumped in the landfill (Asquith, 1982; Kennedy
Engineers, 1980b). HLA personnel interviewed Mr. Steve Kim, Directorate of Health. Services, TAMC,
on December 6,1991. Mr. Kim reported that a mortar round and a rocket casing had been excavated
' from the landfill in the past In addition, Ecology and Environment, Inc., (1981) reported that
90-millimeter (mm) shells exploded onsite when they were struck by a landfill tractor. The EPA Field
Investigation Team (FIT) report (Ecology and Environment, Inc., 1981) cited two explosions of
drummed material labeled methyl ethyl ketone, and indicated that an area may exist where 20- to
25-gallon glass containers containing concentrated sulfuric acid are buried. No records were available
concerning the types, amounts, or volumes of wastes disposed at the Former landfill, but the rate has
been estimated at 100 tons per day (Kennedy Engineers, 1980b).
Although the Former I^pdffl] was not a permitted hazardous waste disposal facility, no provisions
were made to exclude hazardous waste (Ecology and Environment, Inc., 1981). Hazardous wastes
generated by military installations on Oahu before 1980 were inventoried and found to include wastes
being transported to and disposed in the Former landfill (Kennedy Engineers, 1980b). Apparently,
there was "haphazard disposal of material" that appeared to "increase by magnitudes before a visit by
the Inspector General" (Ecology and Environment, Inc., 1981). Loads were not regularly inspected,
and a Former Landfill operator indicated that "anything" could have been dumped at the site
(Kennedy Engineers, 1980b).
In 1980, a State of Hawaii Department of Health (DOH) representative issued a Solid Waste Manage-
ment Permit (operating permit) for the Former I-aTidftn The permit called for closure on or before
December 31,1981, because the DOH and the City and County of Honolulu Board of Water Supply
(BWS) were concerned about potential groundwater contamination to the Schon'eld High-level Water
Body. In September 1983. the Former landfill was dosed. The closure plan did not include
provisions for installations of monitoring wells or a leachate collection system (Kennedy Engineers,
1980a).
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2.5.2 Related Landfill Operations
Before 1967, when the Former landfill was operated as an open burn-type dump, it consisted of two
pits into which solid waste was dumped and burned. Apparently, the remains were then pushed into
adjoining Kaukonahua Gulch. Another disposal area along the gulch leading to the Kaukonahua
Stream bed was used mainly for demolition and construction debris. Bulk refuse was dumped over
the edge of the landfill; the results were underground fires and an open refuse face. When the Former
landfill was designated a sanitary landfill in 1967, operations were converted to the trench method;
wastes were spread in excavated trenches, compacted in layers, and covered with soil on a daily
basis. In addition to the burial of domestic refuse in excavated trenches, demolition and construction
debris was dumped into the small valley located in the eastern midsection of the landfill. Trenching
operations appeared to have been unplanned and poorly organised, and cover soil tended to be
applied only when the trench was completely filled (Kennedy Engineers, 1980b).
A junked car repository, covering approximately 1 acre, was located in the center of the Former
landfill (Figure 2.3). In 1977, the vehicles were sold and removed (Kennedy Engineers, 1980b).
A sewage treatment plant was operated in the northern section of the Former landfill (Figure 2.3). A
1977 topographical survey of the landfill depicts four circular areas, concrete pipes, and a sludge tank
in the area of the plant (R.M. Towill Corporation [RMT], 1977). An Environmental Impact Assess-
ment (EIA), describing demolition and abandonment of the sewage treatment plant (U.S. Army Pacific
Environmental Health Engineering Agency [USAPEHEA], 1977), called for in-place abandonment of
the pumphouse, concrete filter bed, septic tank, settling tank, three sludge beds, chlorinator, and
valve sheds. The EIA stated that the abandoned tanks were to be filled with solid waste and covered
with compacted layers of soil. The plant was eventually abandoned, and in 1979, the remaining
sections were demolished and the site was covered. Reportedly, some concrete tanks were not
completely demolished, but were filled with rubble before they were covered (Kennedy Engineers,
1980a). In 1977, most of the landfill had been used for trenches, so the life of the landfill was
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extended in the northern and eastern areas of the landfill by adding an 8-foot lift. Figure 2.4
illustrates the approximate locations of the northern and eastern area fill.
In 1980, an area-fill operation was located near the center of the landfill beside the drainage ditch
(Figure 2.4) that had been placed over a previously trenched area. This unlined drainage ditch
separated the southern and eastern portions from the northern ridge. A 6-foot-high berm was
constructed along the drainage ditch to form this fill area. The placement of fill progressed in a
northerly direction.
Hospital, drug, and pharmaceutical waste was dumped in the area of general waste and bulldozed
with the other refuse (Kennedy Engineers, 1980b). Mr. Kim verified that infectious waste from TAMC
was dumped in the landfill before 1980 and that disposal had been allowed by state permit and the
Surgeon General The state later withdrew its approval (HLA, 1992b). Infectious waste disposal was
banned by the DOH as of December 31,1980 (Kennedy Engineers, 1980b). Digested wastewater
sludge was spread over the landfill surface in the eastern ridge bordering Waikoloa Gulch before
November 1982 and prior to placement of a soil cap (Ecology and Environment, Inc., 1981). Although
laboratory analyses confirmed the presence of heavy metals in the sludge, extraction procedure
toxicity tests (EP TOX) were not performed (Ecology and Environment, Inc., 1981).
Landfill operations ceased on December 31,1981, and closure occurred in two phases. The landfill
surface was graded and covered with a layer of compacted soil 2 to .2-1/2 feet thick. Closure was
initiated in August 1982 and was 95 percent complete by the end of 1983. Reportedly, the landfill
was to be periodically monitored and inspected for any deficiencies, and corrective activities were to
be initiated, if necessary (USASCH, 1983). However, there is no record of monitoring and inspections
being performed. As a result, landfill subsidence has resulted in numerous cracks and deterioration of
the landfill cap.
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c:
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
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
Wabiawa 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 April 11,1996, the Army presented the Proposed Plan for OU 4 at Schofield Barracks to the public
for review and comment The Proposed Plan summarizes information collected during the OU 4
PA/SI and RI and other documents in the Administrative Record for the Schofield Barracks RI/FS that
are available at the above local repositories. In addition, the proposed plan Sinn-marines the
alternatives contained in the FS and outlines the selected remedy.
Comments regarding the Proposed Plan were accepted during a 30-day public review and comment
period that began on April 11,1996. A public meeting was held on May 1,1996, at 7:00 p.m. in the
Hale Koa at Wahiawa District Park, Wahiawa, Hawaii. At that time, the public had the opportunity to
discuss the proposed plan with the Army, EPA, and the Hawaii DOH. In addition, written comments
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were accepted during the public comment period. However, no written comments were received
during the public comment period. 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.
2.7 Scope and Rolo of Operabl* Unit
The role of OU 4 in the overall NFL program for Schofield Barracks is to identify and eliminate
hazardous wastes associated with the Former T-andftn that pose a threat to human health and the
environment OU 1 addresses other onpost sites that were suspected to be sources of TCE
contamination. Basewide groundwater contaminated with TCE is addressed under OU 2. OU3
addresses other sites that are suspected contamination sources at Schofield Barracks not covered by
other OUs.
The objectives of the OU 4 program are to:
• Investigate the site to identify adverse impacts on groundwater, surface water, soil, or air
caused by the Former Landfill
• Evaluate the risks to human and ecological receptors based on impacts to these media
• Evaluate and select appropriate containment and monitoring alternatives
A PA/SI and RI was performed at OU 4. The SI and RI activities conducted for OU 4 included soil-gas
sampling and analysis, surface-water sampling, surface-soil sampling, subsurface-soil sampling,
groundwater sampling, and lystmeter sampling. Because TCE was detected in subsurface-soil
samples, groundwater samples, and lysimeter samples, it is likely that the Former T.atidfm is
contributing contaminants to the groundwater.
2.8 Site Characterization
To assess site characteristics soil-gas, surface-soil, subsurface-soil, surface-water and sediment,
landfill gas, pore water, groundwater, and ambient air sampling were performed as a part of the RI/FS
activities. A summary of chemicals of potential concern (COPCs) for OU 4 is presented in Table 2.1.
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Landfill contents were not characterized because EPA's Presumptive Remedy for CERCLA Municipal
Landfill Sites guidance document (EPA, 1993a) indicates that characterization of a landfill's contents
is not necessary or appropriate for selecting a response action for CERCLA municipal landfill sites. A
summary of the sampling results for each of the above media is provided in the following paragraphs.
2.8.1 Soil Gas
Shallow soil-gas surveys were performed at the Former landfill as a part of the SI and the Phase I and
Phase n RI/FS field programs. Several VOCs were detected in the shallow soil-gas samples that were
obtained from approximately 10 feet bgs. The most prevalent VOCs were TCE, trichloroethane (TCA),
vinyl chloride (VC), and total volatile hydrocarbons (TVH). The TVH are believed to be primarily
methane. Figure 2.5 shows the location of TCE detections from the OU 4 Phase IRI. VOC detections
were bounded by nondetections, providing an approximation of the lateral extent of contamination in
each area. Low concentrations of TCE were detected in a large portion of the central area of the
landfill as well as in the northern, northeastern, and southern portions of the landfill. The highest
concentrations of TCE were detected in the northeastern portion of the landfill. Low concentrations
of VC were detected in small areas in the central, northern, and northeastern portions of the landfill,
but the lateral extent of these VC detections is very limited. Low concentrations of TCA were
detected in some areas of the northern and central portions of the landfill and along the western
boundary as shown in the OU 4 Phase n SAP (HLA, 1995a). Low levels of TVH were detected across
the landfill area.
Deep soil-gas samples were collected at several depths from soil borings installed during the Phase I
RI. Other than TVH and benzene, ethylbenzene, toluene, and total xylenes (BTEX) compounds, the
only VOCs detected in the deep soil-gas samples were methylene chloride, tetrachloroethene (PCE),
and TCE Low concentrations of methylene chloride were detected in three of the borings at 50 to
100 feet bgs. PCE was detected at 100 feet bgs in a boring in the southeastern part of the landfill, and
TCE was detected at two depths (50 and 100 feet bgs) in a boring in the northeastern portion of the
landfill in the area where the highest concentrations of TCE were detected in the shallow soil gas.
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TCE was also detected in concentrations up to 34 parts per million (ppm) in gas samples collected
/£!
from piezometers (near Boring 8) in the northeastern portion of the landfill during the in situ air \J
permeability test TCE detections in the piezometers extended to depths of 200 feet bgs.
These results indicate that TCE is the most prevalent chemical detected in both the shallow and deep
soil gas. The highest concentrations of TCE in soil gas occurred in the vicinity of Boring 8 in the
northeastern portion of the landfill (Figure 2.5).
2.8.2 Surface Soil
Surface-soil samples were collected as a part of the Phase IRI. Only very low concentrations of three
organic compounds and a few metals were detected in the surface-soil samples. The organic
compounds included one explosive compound, one pesticide compound, and one polychlorinated
biphenyl (PCB) compound. The detections of both metals and organic compounds were below EPA
Region IX Preliminary Remediation Goals (PRGs). These low levels of surface-soil contamination
indicate that surface soil in the vicinity of the Former Landfill has not been impacted by contaminants
contained within the landfill at concentrations above EPA risk-based levels.
2.8.3 Subsurface Soil
As a part of the Phase I RI, eight borings distributed throughout the landfill area were drilled through
the landfill mass into the subsurface soil underlying the buried refuse (Figure 2.6). Samples were
collected from the subsurface soil beneath the refuse. The only organic compounds detected other
than very low concentrations of suspected laboratory contaminants,were one very low concentration
of nitrobenzene from Boring 1 (70.8 feet bgs) in the northwestern portion of the landfill, and a low
concentration of PCE in one sample at 55.5 feet bgs and a low concentration of TCE and
1,2-dichloroethene (1,2-DCE) in a sample from 70.3 feet bgs, from Boring 8 in the northeastern portion
of the landfill. All detections of organic compounds were below the EPA Region IX PRGs for the
respective chemicals. However, concentrations of TCE as high as 3,000 micrograms per liter (Ag/1)
were detected in lysimeter pore-water samples from the same boring in the northeastern portion of the
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landfill where TCE was detected at a low concentration of at a low concentration of 0.068 ng/1 in a
subsurface-soil sample at 70.3 feet bgs.
Several metals were detected in soil samples collected from each of the borings. The metals
detections were relatively uniform across the landfill area and were generally below the correspond-
ing EPA Region IX PRGs with the exception of aluminum and beryllium. Aluminum and beryllium
detections that exceeded PRGs were at similar concentrations to those found in background samples
collected as part of the OU1RI (HLA, 1995b). For example, concentrations of aluminum detected in
soil samples from the landfill range from 44,200 fig/kg to 129,000 fig/kg and background soil sample
aluminum concentrations range from nondetect to 125,000 jig/kg and concentrations of beryllium
detected in soil samples from the landfill range from nondetect to 3.51 ng/kg and background soil
sample beryllium concentrations range from nondetect to 2.05 ^g/kg.
Detections of organic compounds in subsurface soil were very limited and did not indicate a pattern
of contamination. However, the TCE detection in Boring 8 did correlate with TCE contamination in
the shallow and deep soil-gas and pore-water samples from this area of the landfill.
2.8.4 Surface Water and Sediment
The only surface-water bodies in the vicinity of the landfill are Kaukonahua Stream and its tributaries
north of the landfill. During the SI and Phase I and n RI/FS field investigations, surface-water and
sediment samples were collected from several locations along Kaukonahua Stream and its tributaries.
Very low concentrations of a few organic compounds were detected in surface-water samples during
each of the three rounds of sampling. These organic compounds consisted primarily of low levels of
VOCs and semivolatile organic compounds (SVOCs) that are likely laboratory contaminants. Low
concentrations of a few pesticides and explosive compounds were also detected in both surface water
and sediment samples. The concentrations detected were below the EPA Region DC PRGs for the
respective chemicals for each matrix. The detections did not appear to exhibit a trend or to be related
to contamination within the body of the landfill. Further information regarding surface-water and
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sediment sampling results is provided in the PA/SI Report (HLA, 1992a), the OU 4 Phase n SAP (HLA,
1995a), and the OU 4 FS (HLA, I995c).
2A5 Landfill Gas
Five landfill gas monitoring wells were installed during the Phase n RI/FS field program. Gas samples
i
were collected from these wells and analyzed for VOCs for three monthly monitoring events. These
results indicate the presence of numerous VOCs in the landfill gas in concentrations up to 2,200 parts
per billion volume (ppbv). The highest concentrations of petroleum-related VOCs, such as benzene,
were detected in a gas monitoring well (GMW-4) in the central portion of the landfill. The highest
concentration of chlorobenzene, which was the VOC detected at the highest concentration, was also
detected in this well. The highest concentration of chlorinated hydrocarbons were detected in
GMW-1 in the northeastern part of the landfill near soil Boring (Lysimeter) 8 (Figure 2.6).
2.8.6 Leachate
Leachate was not found during the Phase I and Phase n RI/FS field program, indicating that leachate is
not accumulating beneath the landfill in the areas investigated. Therefore, lysimeters were installed
in the unsaturated subsurface soil below the landfill contents. Samples of pore water were collected
from these lystmeters. The concentration of contaminants in the pore-water samples provides an
estimate of what the characteristics of leachate could be if it were to accumulate beneath the landfill.
These pore-water samples indicated the presence of low concentrations of several VOCs in pore water
from all areas sampled. The only VOC compound present in concentrations above 100 jtg/1 was TOE
in Lysimeter 8 in the northeastern portion of the landfill (Figure 2.6).- TCE was detected in samples
from Lysimeter 8 in concentrations up to 3,000 /ig/1. The higher levels of contamination in the
samples from Lysimeter 8 were consistent with detections of TCE in shallow and deep soil-gas and
subsurface-soil samples from this area.
2.8.7 Groundwater
As a part of Phases I and n of the RI/FS field program, four groundwater monitoring wells were
installed around the Former Landfill
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Three rounds of sampling data were collected for MW-4-1, MW-4-2/2A, MW-4-3, and MW-4-4. The
groundwater sampling results of the three rounds for these four wells indicated that the groundwater
beneath the landfill contains low levels of TCE, carbon tetracbloride (CCI^), carbon disulfide, and
chlorofoim. The only VOCs detected above MCLs were TCE and CCL* in MW-4-1, southeast of the
landfill, TCE in MW-4-3 to the south-southeast and MW-4-4 to the north of the landfill (Figure 2.6).
TCE was detected below the MCL (5 /ig/1) in MW-4-2/2A to the northwest of the landfill VOCs have
not been detected in Well 3-3103-01, which is the nearest offsite well located approximately 1 mile to
the northeast and believed to be downgradient of the Former Landfill. Low concentrations of a few
pesticides were also detected in groundwater samples collected from these wells, but the pesticide
detections were inconsistent and were below MCLs and EPA Region IX PRGs for tap water. On the
basis of these results, VOCs from the Former landfill appear to have impacted groundwater beneath
and adjacent to the landfill; however, evidence of offsite migration of contaminants has not been
detected in irrigation wells to the north.
2.8.8 Ambient Air
Upgradient and downgradient ambient air samples were collected and analyzed as a part of the
Phase IRI. No organic compounds were detected in either the upgradient or downgradient ambient
air samples at the time of sampling indicating that, under similar meteorological conditions, the
ambient air in the vicinity of the Former Landfill has likely not been impacted by contaminants
present in the landfill contents.
2.8.9 Summary of Site Characterization
The only media associated with the Former Landfill, other than landfill contents and landfill gas, that
appear to have been impacted by contaminants within the landfill are soil gas, subsurface soil, and
groundwater. Leachate was not observed; however, high concentrations of TCE were present in the
pore-water samples from Lysimeter 8. Very low concentrations of a few organic compounds and some
metals were detected in surface soil, surface water, and sediments; however, all of the chemicals
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detected were below their corresponding EPA Region DC PRGs or MCLs. There also did not appear to
be any consistent pattern to these low-level detections.
Low concentrations of VOCs were detected in shallow and deep soil gas from several locations within
the landfill area. Low concentrations of VOCs were also detected in subsurface-soil samples and pore-
water samples. The only area of the landfill having concentrations of VOCs in each of these media
was the northeastern portion of the landfill in the vicinity of Lysimeter/Boring 8. Therefore, this area
of the landfill may contain elevated concentrations of TCE, which can be roughly estimated by the
extent of the TCE detections in shallow soil gas (Figure 2.5). However, based on available data it is
not possible to accurately define the extent and volume of the media impacted by elevated TCE
concentrations.
2.9 Summary of Site Risks
A baseline risk assessment was prepared to evaluate the potential human and ecological risks posed
by chemicals detected at OU 4. This baseline risk assessment is provided as Appendix I in the OU 4
FS Report (HLA, 1995c). The data collected during the Phase I and Phase n RI were used as the
primary source for analytical data for the human health risk assessment (HRA) and the ecological risk
assessment (ERA). The media of interest for the risk assessment were surface soil, surface water, and
sediment These are the only media for which a pathway of exposure exists for human or environ-
mental receptors. Further information regarding the procedures for identifying media of interest,
identification of COPCs, and risk estimation procedures are provided in the baseline risk assessment
for OU 4 (HLA, 1995c). Risk from potential exposure to groundwater was evaluated under the scope
of OU 2 which separately addressed installation-wide contaminated groundwater. Specific
conclusions of that risk assessment are available in the ROD for OU 2 and sources referenced therein.
The analytical sampling data for surface soil, surface water, and sediment were screened in the HRA
to select a list of site-related COPCs. Table 2.1 presents selected COPCs for each media type at OU 4.
The maximum detected concentrations in soil and sediment were compared to the risk-based
screening concentrations (RBSCs) for industrial land use prepared by EPA Region DC. If the maximum
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detected concentration did not exceed the RBSC, the chemical was not selected as a COPC and was
not included in the risk assessment For inorganic chemicals detected in soil, an additional
comparison was made to the 95 percent upper confidence limit for background concentrations
presented in the Final OU1RI Report (HLA, l995b). If the maximum detected concentration of an
inorganic chemical did not exceed the background concentration, the chemical was not included in
the risk assessment For surface water, if the maximum concentration did not exceed the MCL, the
chemical was not retained as a COPC. To be conservative, drinking water standards (MCLs) were
used, although surface water on post is not used as a drinking water source. For chemicals exceeding
the MCL, a further comparison was made to the EPA Region DC RBSC for tap water use. If the
maximum detected concentration was below the EPA Region IX tap water RBSC, the chemical was
not retained as a COPC. The HRA considered three potential future receptor populations: a remedial
worker, a long-term recreational user, and military personnel involved in field maneuvers or field
exercises. Each of these populations was evaluated for ingestion of and dermal contact with surface
soil, surface water, and sediment No current human populations were identified at the site.
Potential exposures were evaluated for both average case and reasonable maximum exposure (RME)
scenarios. Different exposure and chemical intake assumptions were used to differentiate between
the average and RME scenarios. Average and RME exposure point concentrations (EPCs) for COPCs in
each media were estimated as the arithmetic mean and 95 percent upper confidence limit,
respectively, as recommended by EPA.
Carcinogenic risks and noncarcinogenic health effects were characterized for each population by
combining the estimated chemical intakes with the appropriate toxicity factors (i.e., carcinogenic
slope factors and noncarcinogenic reference doses). Only chronic toxicity factors were used in the
HRA. Oral toxicity factors were used to evaluate both oral and dermal exposures, with the exception
of dermal exposure to carcinogenic polynuclear aromatic hydrocarbons (PAHs). In accordance with
EPA guidance, potential risks from dermal exposure to carcinogenic PAHs were not included in the
risk characterization. Because background concentrations for inorganics were available, risks were
characterized as both total risks and incremental risks (i.e., the contribution of background concentra-
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tions of inorganics has been subtracted from the total risk). Table 2.2 presents the RME total and
incremental carcinogenic risks and noncarcinogenic hazard indices for each of the three potentially
exposed populations. None of the estimated hazard indices exceeds 1.0, the EPA benchmark for
concern for noncarcinogenic health effects. The maximum total carcinogenic risk (including
background) is 1.58 x 10"*, which is at the lower limit of EPA's acceptable risk range (i.e., 10"1 to 10"6).
None of the incremental risks (i.e., with background risks subtracted) exceeds the lower acceptable
limit of 1 x 10"6.
In addition to the quantitative HRA, a qualitative ERA was also developed. Because of the physical
characteristics of the site (e.g., buried waste in a capped landfill), opportunities for exposure of
ecological receptors are very limited. No clearly distinguishable patterns of contamination were
detected in either surface soil, surface water, or sediments in Kaukonahua Stream. Based on the
limited number and low concentration of organics detected, the naturally occurring background
concentrations of inorganics, and the limited opportunity for contact with surface water and/or
sediments (due to the ephemeral nature of surface water at the site), no hazards to local plant and
animal life were noted.
2.10 Description of Alternatives
This section identifies and describes the four alternatives that were developed based on EPA's
Presumptive Remedy (EPA, 1993a). The action-specific applicable or relevant and appropriate
requirements (ARARs) considered for these alternatives are summarized in Table 2.3. No chemical-
specific ARARs were identified for the site because EPA's Presumptive Remedy for CERCLA
Municipal Landfill Sites guidance document (EPA, 1993a) indicates that chemical characterization of
a landfill's contents is not necessary or appropriate for selecting a response action for CERCLA
municipal landfill sites, and no location-specific ARARs were found to be relevant to the site. A
detailed description of each alternative is provided below.
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2.10.1 Alternative 1 • No Further Action/Institutional Controls
Alternative 1 includes the following components:
• No Further Action
• Institutional Controls
Long-term groundwater monitoring using existing monitoring wells
Five-year site review
Access restriction and site security
These components of Alternative 1 are described below.
No Further Act/on
Under Alternative 1, no further action would be performed to reduce the mobility, toxicity, or volume
of the contaminated media. The No Further Action alternative is required as part of the NCP and
provides a baseline to compare other alternatives against. Because the landfill was capped with
approximately a 3-foot-thick layer of low-permeability material in 1983, a component of this
alternative is No Further Action.
Institutional Controls
Institutional controls such as groundwater monitoring, five-year site review, and access restriction and
site security, are used to supplement engineering controls for short- and long-term management to
prevent or limit exposure to hazardous substances. Although institutional controls do not reduce
mobih'ty, toxicity, or volume of contaminants, they will likely be necessary to maintain the integrity of
any response action selected for OU 4 and may reduce the potential for human exposure to
contaminated landfill contents and contaminated groundwater beneath the landfill.
Groundwater Monitoring. Groundwater monitoring is included in Alternative 2 to monitor the
effectiveness of the existing landfill cap with respect to preventing further groundwater
contamination. Groundwater monitoring will also be addressed as part of the OU 2 FS to evaluate any
impact of the landfill on downgradient groundwater quality.
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For the purposes of the FS, the conceptual monitoring well network includes the following six existing
monitoring wells, which are illustrated in Figure 2.7:
• MW-2-2
• MW-4-1 (3-3004-1)
• MW-4-2A
• MW-4-3 (3-3004-3)
• MW-4-4
• 3-3103-01
Monitoring Wells MW-4-1, MW-4-2A, MW-4-3, and MW-4-4 are wells that were installed during the
RI specifically for the purpose of monitoring groundwater in the vicinity of the Former landfill.
Monitoring Well MW-4-2A provides monitoring of the groundwater immediately upgradient of the
Former Landfill. Monitoring Wells MW-4-1, MW-4-3, and MW-4-4 monitor groundwater either
downgradient or crossgradient of the Former Landfill. Monitoring Well MW-2-2, installed as part of
the OU 2 RI, has been included to provide an additional monitoring point upgradient of the Former
Landfill. As indicated by the conceptualized flow lines in Figure 2.7 two upgradient groundwater
sources may impact the Former Landfill. These sources are (1) water recharging from the Koolau
Mountain Range (which is monitored by MW-2-2) and (2) water recharging from the Waianae
Mountain Range (which is monitored by MW-4-2A). Monitoring Well 3-3103-01 is an offsite irrigation
well that has been included to provide monitoring of offsite groundwater downgradient of the Former
Landfill.
Samples will be collected from these wells on a semiannual basis. The only analytes that have been
detected above MCLs established by the EPA are VOCs (i.e., carbon tetrachloride and TCE).
Therefore, groundwater samples will be analyzed for these three compounds on a semiannual basis.
Samples will be analyzed for the VOCs presented in Table 2.4 on an annual basis to confirm that no
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other VOCs have migrated to the groundwater system. Because VOCs generally migrate more quickly
J in the subsurface than other analytes, it will not be necessary to analyze the samples for the other
analyte groups unless an increasing trend is observed in the detected VOC concentrations.
Water levels will be monitored in the wells included in this monitoring network on a semiannual basis
in conjunction with collection of groundwater samples. These water-level measurements will be used
to evaluate any changes in groundwater flow patterns in the vicinity of the Former Landfill.
Five-Year Site Review. In accordance with CERCLA, a site review will be conducted every five years
until the PRGs for the groundwater under the landfill are achieved. Groundwater data for the
previous five years for OU 4 will be evaluated and presented in a report to assess whether additional
action is warranted.
Access Restrictions and Site Security. Access restrictions and site security are used to (1) limit
— human exposure to the landfill contents, (2) prevent trespassing, and (3) protect the integrity of the
cap. The existing chain-link fence around the perimeter of the accessible portions of the landfill
would be maintained as an access restriction. Signs that warn of potential health risks will be posted
on the fence. The Former Landfill is part of a military installation that has a guard stationed at the
entrances to monitor access to the installation 24 hours per day. These security measures will be
maintained.
2.10.2 Alternative 2 - Maintenance off the Landfill Cover
Alternative 2 includes the institutional controls that were previously described as part of Alternative 1
with the following additional components:
• Regrade existing landfill cover to generally match the 1983 engineered drainage grade
• Perform long-term maintenance of the landfill cover
• Maintain existing passive landfill gas venting
f* • Install additional gas monitoring points at the perimeter of the landfill
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These components of Alternative 2 are described below.
Kogrado Existing Landfill Covor
Regrading the existing landfill cover involves backfilling and compacting areas on the cover where
subsidence has occurred, primarily in the fonner trench locations, to match the previously engineered
grade. Low-permeability borrow material will be transported from local sources and placed and
compacted in areas where subsidence has occurred. The volume of borrow material required to fill
the fonner trench areas to match existing grade was estimated using the results of the visual survey
conducted as part of the Phase n RI. Based on the visual survey, it was estimated that the fonner
trench areas have subsided approximately 2 feet on average. It is estimated that approximately
18,000 cubic yards of borrow material will be required to restore the former trench areas to existing
grade.
The TerraModel* computer program (Plus ffl Software, Inc., Release 8.33) was used to estimate the
additional volume of borrow material required to regrade the landfill cover to match the original,
engineered grade. TerraModel* estimates cut/fill volumes by comparing topographic information.
TerraModel* was used to compare the as-built drawings prepared for the cover in 1983 (Figure 2.8) to
a survey map prepared for the cover in 1995. TerraModel* indicates that approximately 40,000 cubic
yards of borrow material will be required to restore the existing grade.
Repairs to the sideslopes of the existing cover will be performed to cover the areas of exposed waste
identified in Figure 2.9. Repairs to the sideslopes will be made by placing and compacting fill
material on the sideslopes to cover any exposed areas. Heavy equipment traffic on the sideslopes
(i.e., bulldozers) will be minimized to reduce the impact of construction activities on slope stability.
Areas of the cover that require revegetation will be hydroseeded using a readily available seed
mixture, such as a mixture of Buffalo grass and annual rye, to miTmrrigB erosion. It is anticipated that
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the new vegetative cover will minimize erosion until the Guinea grass becomes re-established in the
areas affected by construction activities. Erosion control matting will be used, as required, on the
affected areas of sideslopes to minimize erosion until the vegetative layer is established.
Improvements will be made to the existing surface drainage illustrated in Figure 2.8 to repair existing
erosion and prevent further erosion.
Long-farm Maintenance of Landfill Cover
Long-term maintenance of the landfill cover will be conducted in accordance with the postclosure
ARARs identified in Hawaii Administrative Rules (HAR) §11-58.1-16. The postclosure requirements
for a Municipal Solid Waste Landfill (MSWLF) require that the integrity and effectiveness of any final
cover be maintained, including making repairs to the cover, as necessary, to correct the effects of
settlement, subsidence, erosion, or other events and preventing run-on and runoff from eroding or
otherwise damaging the final cover. The results of the long-term settlement tests indicate that
approximately 3 to 6 inches of settlement may be expected during the first two years after the cap
improvements are completed due to the additional cover material weight. Periodic maintenance may
be required to repair damage to the cover caused by additional settling.
Long-term maintenance of the landfill cover may include the following:
• Inspecting the cover quarterly and after heavy rainfall events for evidence of damage due to
erosion, settlement, slumping, drought, fire, pestilence, debris accumulation, animal burrows,
or any other adverse conditions.
• Making repairs to the cover, as necessary to correct the effects of erosion, settlement,
slumping,, drought, fire, pestilence, debris accumulation, or any other adverse condition.
• Mowing the existing Guinea grass quarterly prior to the quarterly cap inspections.
If damage to the cap is not noted in four consecutive quarterly inspections, the frequency of
inspection and mowing of grass may be reduced to a semiannual basis.
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Passive Landfill Gas-Venting
Passive landfill gas-venting is included as part of this alternative to provide a pathway for landfill gas
to escape through the improved cover to relieve gas pressure in the landfill. The passive landfill gas-
venting will consist of the five existing monitoring wells shown in Figure 2.10, with minor modifica-
tions. Minor modifications include extending the existing pipes to ensure that the pipes extend
4.0 feet above the final surface after grading operations are completed. The existing pipe will be
vented to the atmosphere. For protection of the existing landfill gas wells, a concrete collar will be
placed around the existing pipes to approximately 24 inches above finish grade. These enhancements
will provide structural protection of the landfill gas monitoring points and will keep rainfall out of the
open pipe.
Poiimofer Landfill Gas Monitoring
Landfill Gas (LFG) monitoring wells will be installed around the perimeter of the landfill to evaluate
the subsurface migration of LFG. The LFG monitoring system will include the nine gas monitoring
wells conceptually shown in Figure 2.11. LFG monitoring wells are not proposed in areas of the
landfill perimeter where the slopes are so steep that the perimeter gas wells would be below the depth
of fill in the Former Landfill. The perimeter gas wells will be monitored quarterly for methane to
evaluate compliance with ARARs.
2.10.3 Alternative 3 • Maintenance and Revegetation off the Landfill Cover
Alternative 3 includes the institutional control components that were previously described as part of
Alternative 1 and the components that were previously describes as part of Alternative 2, with this
additional component:
• Remove Guinea grass from the existing cover and revegetate.
Guinea grass is currently used as the vegetative layer on the existing cover. Although Guinea grass
has generally controlled erosion on the existing cap since 1983, it may be appropriate to consider
other types of vegetation for an erosion layer for the following reasons:
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• Guinea grass tends to have a relatively extensive root system that could damage the cap.
• Guinea grass is stalky and grows relatively tall (approximately 10 feet), making it more
difficult to detect cracks or areas of subsidence on the cover during inspections and increasing
the cost of cover maintenance.
Based on the considerations provided above. Alternative 3 includes removal of the existing Guinea
grass using an herbicide (such as a 10 percent solution of Roundup*). An herbicide may be the only
effective means of removing the existing Guinea grass from the cover. If the Guinea grass is not
completely removed, it would be difficult for another type of vegetation to establish itself on the
cover, given the invasive nature and extensive root system of Guinea grass.
Use of Roundup* as part of the revegetation program is not expected to cause human or environmen-
tal health concerns. Glyphosate, the common chemical name for Roundup®, has low toxicity to
humans and is classified as Group E (evidence of noncarcinogeniciry in humans). Glyphosate is
poorly absorbed dermally. Inhalation toxicity studies were not required during reregjstration
procedures by EPA because of its nonvolatility. Glyphosate adsorbs strongly to soil and is expected to
be immobile in soil. Glyphosate is only slightly toxic to nontoxic to birds, fish, aquatic invertebrates,
and mammals.
Exposure to workers and applicators is not expected to be of concern because of glyphosate's low
toxicity. Splashing of product can, however, cause skin and eye irritation. Manufacturer's recom-
mendations for personal protective equipment must be followed to reduce the potential for exposure.
Application of Roundup® should be done in accordance with the requirements of the Worker
Protection Standard (40 Code of Federal Regulations [CFR] 170) (EPA, 1993b).
The cover may be revegetated using grasses such as a mix of Buffalo grass (buchloe dactyloides) and
annual rye (lolium multiforum) grass. Buffalo grass is a turf-building warm season grass that is more
drought tolerant, and insect resistant Annual rye is an annual grass that will be used to provide
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Decision Summary
temporary erosion control while the Buffalo grass comes in. Both species have shallow root systems
mowing and (2) annual application of an herbicide such as Roundup* for spot control, and to control
reinvasion of Guinea grass around the perimeter of the landfill.
2.10.4 Alternative 4 • Maintenance and Revegetatlon of the Landfill Cover with
Vapor Extraction
Alternative 4 includes the components that were previously described as part of Alternative 3, with
the following additional component:
• Install a vapor extraction system in the vadose zone beneath the Former T-andfill to remediate
the area identified in Figure 2.12.
The conceptual layout of the vapor extraction system consists of three vapor extraction wells, six
piezometers installed 50 feet bgs, and an equipment shed to house the vacuum blower and associated
equipment The purpose of the vapor extraction system is to remove TCE from the area identified in
Figure 2.12 and reduce the migration of TCE through the vadose zone and, ultimately, to the
groundwater. Piezometers would be used to monitor the performance of the vapor extraction system
by monitoring the vacuum at each piezometer. The conceptual locations of the three vapor extraction
wells, the six piezometers, and the treatment shed are illustrated in Figure 2.13. Two of the three
proposed vapor extraction wells would require installation and the other one is an existing vapor
extraction well, VX-3. In addition, three of the six piezometers would require installation and the
other three are existing piezometers, PZ-3, PZ-5, and PZ-9. The existing vapor extraction well and the
three existing piezometers were installed during the in situ air permeability tests conducted as part of
the Phase H RI.
It is estimated that a maximum of 170 pounds per year (14 gallons) of TCE vapor could be emitted
from the three vapor extraction wells combined. This estimate was made using the highest TCE vapor
concentration (34 ppm) measured during the in situ air permeability test conducted as part of the
Phase n RI and an estimated vapor flow rate from each of the three vapor extraction wells of 10 cubic
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Decision Summary
feet per minute (cfm). The air discharge limit in Hawaii is 0.1 ton per year or 200 pounds per year of
each hazardous air pollutant Based on available data, the offgas from the vapor extraction system
will not require treatment before being discharged to the atmosphere. Therefore, offgas treatment is
not included in this alternative.
Based on the vapor temperature from Well VX-3 during the in situ air permeability tests and the
average yearly temperatures for Honolulu, Hawaii, it is estimated that approximately 1 gallon per day
of liquids may form in the air-moisture separator.; It has been assumed for costing purposes that the
liquids from the air moisture separator will be nonhazardous. The nonhazardous liquid would be
transported to the Schofield Barracks water treatment facility for disposal. However, if the chemical
characterization results indicate that the liquid is hazardous and at concentrations that exceed
acceptance levels for the Schofield Barracks water treatment facility, the liquid will be sent to a
Resource Conservation and Recovery Act (RCRA)-approved treatment facility (i.e., incinerator) for
treatment and disposal.
Operation of the system is assumed to require two operators for 10 hours per week to collect samples,
perform equipment maintenance, adjust system operating conditions, and record operating data. The
equipment sizing and operation and maintenance (O&M) requirements are based on the initial
conditions found at the site during the RI and soil vapor extraction (SVE) pilot studies. As the vapor-
phase TCE concentrations decrease over time, vapor extraction wells may be eliminated from the
system.
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
NCP criteria. A summary of the comparative analysis of alternatives is provided in Table 2.5.
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 than
\^ that which currently exists. Overall protection of human health and the environment would be
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increased by Alternatives 2, 3, or 4. Alternatives 3 and 4, which involve revegetating the existing
cover, may be more protective than Alternative 2, because revegetation of the cover may enhance
evapotranspiration and reduce erosion due to surface-water runoff, thereby further reducing
infiltration through the cover. Alternative 4, which involves treatment of a potential hot spot, may
provide some additional protection over Alternatives 2 and 3; however, the volume of TCE that may
be removed is estimated to be very small and may not significantly reduce contaminant transport to
groundwater.
2.11.2 Compliance with ARARs
Alternative 1 would not comply with action-specific ARARs because no further action would be
performed at the Former Landfill. Alternatives 2, 3, and 4 will be in compliance with ARARs because
each of these alternatives include maintaining the landfill cover, implementing groundwater and LFG
monitoring programs, and implementing institutional controls.
2.11.3 Long-term Effectiveness and Permanence
Alternative 1 would not provide any additional risk reduction over the long term. Alternatives 2, 3,
and 4 provide an increase in long-term effectiveness and permanence by improving the existing cap
and implementing long-term maintenance and groundwater monitoring programs. The effectiveness
of Alternatives 2 and 3 can be assessed by periodic landfill cover inspections, perimeter gas
monitoring, and long-term groundwater monitoring. Alternative 4, which involves treatment of a
potential hot spot, may provide some additional long-term effectiveness over Alternatives 2 and 3;
however, the volume of TCE that may be removed is estimated to be very small and may not
significantly reduce contaminant transport to groundwater. Therefore, the effectivenes of TCE
removal may be difficult to assess. There will be no risk from residuals remaining at the conclusion of
remedial activities for Alternatives 2,3, and 4 because there are no complete exposure pathways as
discussed in the Final OU 4 FS and the landfill cover will be maintained indefinitely.
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2.11.4 Reduction in Toxicity, Mobility, and Volume
Alternative 1 does not provide any reduction in toxicity, mobility, or volume. Alternatives 2, 3, and 4
provide a reduction in mobility by improving the existing cap and providing long-term maintenance
of the cap. Alternatives 3 and 4 may reduce mobility more than Alternative 2 because a different
vegetative cover may enhance evapotranspiration and reduce surface erosion, thereby further
reducing groundwater infiltration through the cover.
Alternative 4, which involves remediation of a potential hot spot, also provides a reduction in toxicity
and volume. It is estimated that Alternative 4 may remove between 2 and 14 gallons of TCE per year
using vapor extraction.
2.11.5 Short-term Effectiveness
The short-term conditions at the site would remain unchanged under Alternative 1 because no action
would be implemented. Alternatives 2, 3, and 4 may have short-term impacts associated with
improvements to the existing cap. Alternatives 3 and 4 also involve revegetation of the landfill cover,
which involves short-term impacts associated with the application of an herbicide to the existing
Guinea grass. Alternative 4 involves drilling through the landfill contents, which includes risks
associated with potential exposure to VOCs and UXO. Because a relatively low volume of TCE may
be removed from the potential hot spot, risks associated with drilling through the landfill contents
may not be justified.
2.11.6 Implementablllty
Alternatives 2, 3, and 4 are considered to be implementable with minimal difficulty because they
require only conventional equipment to maintain the landfill cover. Alternative 4 is more difficult to
implement than Alternatives 2 and 3 because it requires intrusive work in an area that may contain
unexploded ordnance and because of an increased danger of subsurface landfill fires resulting from
increased subsurface oxygen levels that may occur during vapor extraction. Alternative 1 is not
considered to be administratively implementable. Implementation of the selected alternative will be
coordinated with EPA and DOH.
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2.11.7 Cost
The net present worth of Alternatives 1 through 4 ranges between $1,100,000 (Alternative 1 - No
Further Action Institutional Controls) and $8,200,000 (Alternative 4 - Maintenance and Revegetation
of the Landfill Cover with Vapor Extraction). Alternative 2 (Maintenance of the Landfill Cover) and
Alternative 3 (Maintenance and Revegetation of the Landfill Cover) both have a net present worth of
$6,800,000. A breakdown of capital cost, O&M cost and net present worth for each alternative is
presented in Table 2.6
2.11.8 State Acceptance
As indicated by DOH approval of the Final OU 4 FS and Proposed Plan, Alternative 3 is more
acceptable to the state than Alternatives 1, 2, and 4.
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
written public comment, the Army, EPA, and the State of Hawaii have determined that Alternative 3
(Maintenance and Revegetation of the Existing landfill Cover) is the preferred alternative for
Schofield Barracks OU 4. The comparative analysis of alternatives indicates that Alternative 3 is
superior to Alternatives 1 and 2 with respect to protection of human health and the environment and
reduction of mobility. The short-term risks associated with implementation of Alternative 3 are
slightly higher than for Alternatives 1 and 2 because Alternative 3 involves application of an
herbicide. However, the long-term benefits associated with Alternative 3 include improving the
integrity of the cover, facilitating quarterly inspections of the cover, and further reducing the potential
for surface-water infiltration, thereby potentially reducing contaminant transport to groundwater.
Although Alternative 4 provides reduction of toxicity and volume where Alternative 3 does not,
Alternative 4 was not selected as the preferred alternative because Alternative 4 involves risks
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Decision Summary
associated with potential exposure to VOCs and UXO. Also, preliminary estimates indicate that only
a minimal volume of contaminants (2 to 14 gallons of TCE) may be removed from the vapor extraction
system on an annual basis. Therefore, the additional cost and lower short-term effectiveness for
Alternative 4 may not be justified.
State acceptance of the selected remedy is indicated by DOH approval of the Final OU 4 FS. As
documented in Section 3.0, no public comments were received during the public comment period for
the OU 4 Proposed Plan indicating community acceptance.
Alternative 3 was previously described in Section 2.10.3. It should be noted that some changes may
be made to the remedy during the detailed design and construction phase. The major costs associated
with this alternative are presented in Table 2.7.
2.13 Statutory Determinations
Under its legal authorities, EPA's primary responsibility at Federal Facility NPL sites is to oversee
response 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 response 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 that permanently and significantly reduces the volume, toxicity, or mobility of hazardous
wastes as their principal element The following sections discuss how the selected remedy meets
these statutory requirements.
Protect/on of Human Health and the Environment
The selected remedy protects human health and the environment by limiting direct contact with the
Former Landfill contents and by restricting surface-water infiltration through the landfill. The current
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and future risks associated with OU 4 in its current condition are within the acceptable range. By
improving the Former Landfill cover, the already acceptable risks will be further reduced. There are
no short-term threats associated with the remedy that cannot be readily controlled.
Compliance with ARARs
The selected remedy will comply with all action-specific ARARs. As documented in the ARARs
analysis in the Final OU 4 FS as approved by EPA and DOH, there are no chemical-specific or
location-specific ARARs. The ARARs are presented below:
• Action-specific ARARs:
Fugitive dust emission limitations contained in HAR ll-60.1-33(a)(l-7)(b).
HAR 11-55-34.02, Appendices A and C, requiring a National Pollutant Discharge
Elimination System (NPDES) permit and monitoring for storm-water runoff associated
with construction activity.
HAR ll-58.1-17(a)(9)(A, B), which requires a notation be placed on the landfill
property following closure of the MSWLF to indicate the land was used as a landfill.
HAR 11-58.1-16, requirements for groundwater monitoring during the postclosure care
period at MSWLF units.
HAR ll-58.1-17(b) requiring postclosure care of the landfill for 30 years.
HAR ll-59-4(f) and (h) limiting the emission of ozone to 100 micrograms per cubic
meter (/ug/m3) in one hour.
HAR 11-60.1-68 requiring monitoring and measurement of VOC emissions if emissions
are greater than 1 ton per year for each air pollutant
• Chemical-specific ARARs
None.
• Location-specific ARARs
None.
Cost Effectiveness
The selected remedy is cost effective because it has been determined to provide overall effectiveness
proportional to its costs. The estimated costs of the selected remedy are approximately equal to the
costs for Alternative 2, but the selected remedy has a better long-term effectiveness. The estimated &M
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cost of the selected remedy is also less than Alternative 4 and provides a better effectiveness
proportional to its cost. The additional cost of Alternative 4 to remove approximately 2 to 14 gallons
per year of TCE is not deemed to be cost effective.
Utilization of Permanent Solutions and Alternative Technologies to the Maximum
Extent Practicable
EPA and the State of Hawaii have determined that the selected remedy represents the maximum
extent to which permanent solutions and treatment technologies can be used in a cost-effective
manner for source control of OU 4. 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; and cost
Although Alternative 4 provides greater reduction of toxicity and volume using treatment, Alterna-
tive 4 involves short-term risks associated with potential exposure to VOCs and UXO. In addition,
only a minimal volume of contaminants would be addressed, therefore, additional cost is not justified.
The selected remedy addresses the principal threats posed by the landfill effectively and cost
effectively.
Preference for Treatment as a Principal Element
The selected remedy does not include a treatment technology, however, treatment is not deemed to
be practicable. The principal threats posed by the site are direct contact with the Former Landfill
contents and migration of VOCs to the groundwater. The selected remedy adequately addresses these
threats by upgrading and maintaining the cover, and the OU 2 (contaminated groundwater) remedy
will further address the groundwater plume. The remedy is consistent with EPA's Presumptive
Remedy for Municipal Landfill Sites (EPA, 1993a) which does not require treatment
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Table 2.1: Chemicals of Potential Concern for OU 4
Media/Chemical
Surface Soil
Arsenic
Beryllium
Chromium
Manganese
Sediment
Arsenic
Beryllium
Chromium
Manganese
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoianthene
Dibenzo(a,h)anthracene
Indeno(l,2,3-c,d)pyrene
Surface Water
Manganese
Nitramine/tetiyl
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Table 2.2: Summary off Total and Incremental Risks
at OU 4 for Potentially Exposed Populations
Remedial worker
Recreational user
Military personnel
Total
1.58E-06
1.30E-06
7.79E-07
loeenicRisk
Incremental*
2.50E-07
3.00E-07
1.43E-07
Nonc_
% %
Hazard Index
Total
2.96E-01
8.81E-02
7.57E-02
Incremental *
l.OOE-01
3.91E-02
2.90E-02
Only the reasonable maximum exposure values are presented.
* Risks associated with naturally occurring levels of background inorganics have been subtracted
from the total risk estimates. The incremental risks are more representative of site-related
conditions than are the total risk estimates.
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,,,.^
Table 2.3: Action-specific Applicable or Relevant and Appropriate Requlremente for
Alternatives 2, 3, and 4 for Operable Unit 4 at Schofleld Army Barracks, Hawaii
Actions
Requirements
Prerequisites
Federal Citation
Hawaii Citation
Fugitive Dust
Emissions
Surface-Water
Control
Institutional
Controls
Long-term
Ground water
Monitoring and
Maintenance of
the Landfill
Cover
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 prevent fugitive dust emissions.
NPDES permit required for offslte discharges and discharges to a POTW.
NPDES permit is not required for onsite discharges, but the substantive
requirements of the permit must be compiled with for onstte discharges,
offsite discharges, and discharges to a POTW.
Monitoring required to ensure compliance with applicable state water
quality standards.
Following closure of all municipal solid waste landfill (MSWLF) units,
the owner or operator must record a notation on the deed to the landfill
facility property, or some other instrument that is normally examined
during title search, and notify the Director of Health that the notation has
been recorded and a copy has been placed in the operating record.
The notation on the deed must in perpetuity notify any potential
purchaser of the property that the land has been used as a landfill facility
and its use is restricted under § ll-58.1-17(b)(3)(C) of the Hawaii
Administrative Rules.
Groundwater monitoring must be conducted throughout the postclosure
care period for the MSWLF unit, unless a demonstration Is made
showing that there is no potential for migration of hazardous
constituents from that MSWLF unit to the uppermost aquifer during the
active life of the unit and the postclosure care period.
A ground water monitoring system that consists of a sufficient number of
wells, installed at appropriate locations and depths, to yield groundwater
samples from the uppermost aquifer that represent the quality of
background water that has not been affected by leakage from the unit
and the quality of groundwater passing the relevant point of compliance
specified by the Director of Health.
Fugitive emissions from excavation of contaminated soil
and construction of pads.
Storm-water runoff associated with construction activity.
Including clearing, grading and excavation, except
operations that result in the disturbance of less than five
acres of total land area, which are not part of a larger
common plan of development or sale.
Storm-water runoff from construction activity.
A MSWLF unit.
§ll-80.t-33(a)(l)
through (7) and (b)
applicable
§11-55-34.02,
Appendices A and C
applicable
§11-55-34.02,
Appendix A -
applicable
§ll-58.M7(a)(9)(A)
relevant and
appropriate
§ll-58.1-17(a)(9)(B)
relevant and
appropriate
§ll-5B.l-16(a)(5)
relevant and
appropriate
relevant and
appropriate
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Table 2.3 (continued)
Actions
Requirements
Prerequisites
Federal Citation
Hawaii Citation
Monitoring wells must be cased in a manner that maintains the integrity
of the monitoring well borehole.
Owner or operator must establish background groundwater quality In a
hydraulically upgradient or background woll(s) for each monitoring
parameters or constituents required in the particular groundwater
monitoring that applies to the MSWLF unit, as determined under
§ ll-58.1-18(d)(t) or (e)(l).
Detection monitoring must be performed. The minimum of detection
monitoring allowed is for the constituents listed in Appendix I to 40 CFR
Part 258. If there is a statistically significant increase over background
for one or more of the constituents listed in Appendix I to 40 CFR Part
258 at any monitoring well at the boundary, then an assessment
monitoring program must be established, unless it can be demonstrated
Ihat a source other than the landfill caused the contamination or that the
statistically significant increase resulted from error in sampling, analysis,
statislical evaluation, or natural variation in the groundwater quality.
If assessment monitoring Is triggered, then the groundwater must be
sampled and analyzed for all constituents listed in Appendix U to 40 CFR
Part 258. If one or more of the constituents listed in this appendix are
detected at statistically significant levels above the groundwater
protection standard established under § 11-58.l-16(e)(8) or (9) in any
sampling event, then at least one additional monitoring well at the
facility boundary In the direction of contaminant migration must be
installed and an assessment of corrective measures must be Initiated
pursuant to § 11-58.1-18(1).
Postclosure care must be conducted for 30 years, unless this time period
is decreased by the Director of Health when it is demonstrated that the
reduced period Is sufficient to protect human health and the
environment or increased by the Director if the Director determines that
the lengthened period Is necessary to protect human health and the
environment.
The integrity and effectiveness of the final cover must be maintained.
§ll-58.1-16(b)(3)
relevant and
appropriate
§ll-58.1-16(c)(5)
relevant and
appropriate
§ll-58.1-16(d)(3)
relevant and
appropriate
§ll-58.1-16(e)(2)
relevant and
appropriate
§ll-58.1-17fb)
relevant and
appropriate
§ll-58.1-17(b)
relevant and
2 of 3
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Table 2.3 (continued)
Actions
Requirements
Prerequisites
Federal Citation
Hawaii Citation
Air Emissions
from the
Passive Landfill
Gas Collodion
System and
Active Vapor
Extraction
System
Gas Treatment
System
The groundwater must ba monitored in accordance with § 11-58.1-16
and the groundwater monitoring system must be maintained.
In the ambient air, the average concentration of ozone measured by a
reference method during any one hour period shall not exceed
100 micrograms per cubic meter of air and the average concentration of
load measured as elemental lead by a reference method during any
calendar quarter shall not exceed 1.5 micrograms per cubic meter of air.
Substantive requirements of permit if exemption listed at
§11-60.l-62(d)(l) cannot be met. Substantive 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.
Obtain a manifest and comply with packaging, labeling, marking, and
placarding requirements.
Air emissions of volatile organic compounds (VOCs) or
lead.
Exemption under §ll-60.1-62(d)(l) cannot be met.
Use of granular carbon filter system and the carbon
filters meet the definition of a RCRA hazardous waste.
appropriate
§ll-58.1-17(b)
relevant and
appropriate
§ll-59-4(f) and (h) •
applicable
§11-60.1-68
applicable
40 CFR 262 and
40 CFR 283
applicable
CFR Code of Federal Regulations
MSWLF Unit Municipal solid waste landfill unit
NPOES National Pollutant Discharge Elimination System
POTW Publicly owned treatment works
RCRA Resource Conservation and Recovery Act
VOC Volatile organic compound
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Table 2.4 Target Compound List for Volatile Organic Compounds and Target
Detection Levels for Water Sample Analyses
Target Detection
Levels
CAS No.
Target Compounds
74-87-3
74-83-9
75-01-4
75-00-3
75-09-2
67-64-1
75-15-0
75-35-4
75-35-3
156-60-5
67-66-3
107-06-2
73-93-3
71-55-6
56-23-5
75-27-4
78-87-5
10061-02-6
79-01-6
71-43-2
124-48-1
79-00-5
10061-01-5
75-25-2
591-78-6
127-18-4
79-34-5
108-88-3
108-90-7
100-41-4
108-10-1
108-42-5
1330-20-7
Chloromethane
Bromomethane
Vinyl chloride
Chloroethane
Methylene chloride
Acetone
Carbon disulfide
1,1-Dichloroethene
1,1-Dichloroethane
1,2-Dichloroethene (reported
as the sum of cis and trans)
Chloroform
1,2-Dichloroethane
2-Butanone
1,1, 1-Trichloroethane
Carbon tetrachloride
Bromodichloromethane
1,2-Dichloropropane
trans-l,3-Dichloropropene
Trichloroethene
Benzene
Dibromochloromethane
1,1 ,2-Trichloroethane
cis-l,3-Dichloropropene
Bromofonn
2-Hexanone
Tetrachloroethene
1,1,2,2-Tetrachloroethane
Toluene
Chlorobenzene
Ethylbenzene
4-Methyl-2-pentanone
Styrene
Total xylenes
2
7
1
10
3
10
10
5
10
10
10
3
10
10
3
10
3
10
3
3
10
2
10
10
10
3
10
10
10
10
10
10
10
CAS Chemical Abstracts Service
/ig/1 Micrograms per liter
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Table 2.S Summary of Comparative Analyst* of Alternatives
Alternative
Alternative 1 - No Further
Action
Alternative 2 - Regmde
Landfill Cover
Overall
Protection of Human Heellli and
Ike Environment
Provides no additional protection
against onsite or offslle exposure.
Improvements to the existing cap
reduce the risk of exposure to
landfill contents and may reduce
Compliance wllhARAKs
Would not comply with
ARARs.
Expected to be In compliance
with action- and locatlon-
spaclfic ARARs. Mb
Loaf/lerm Effectiveness
•nil Permanence
Would not provide any
additional risk reduction
over long term.
Improved reliability over no
action. Requires long-term
maintenance to maintain
MedtdhmofMTV
A treatment technology Is
not included as part of
this alternative.
A treatment technology Is
not Included as part of
this alternative.
Shorl-term Effectiveness
No short-term Impacts.
Lass than six months required to
Implement the components of this
alternative. Potential risk to
IraplsmsnfMBiltly
Implemantable,
however, no action
will likely be
unacceptable because
It does not comply
with ARARs.
Implementable
Net Present
Wort. Cost
1$)
1,100,000
6,800.000
Alternative 3 - Regmda and
Revegetate Landfill Cover
leaching of contaminants to
groundwater through decreased
Infiltration. Groundwaler
monitoring will provide protection
of human health and the
environment by assessing any
changes In groundwater
contaminant concentraltona tat
groundwater below the Former
Landfill. Institutional controls will
further prevent onsite exposure.
reduce the risk of exposure lo
landfill contents and may reduce
leaching of contaminants to
groundwater through decreased
Infiltration. Groundwater ,
monitoring will provide protection
of human health and the
environment by assessing any
changes In groundwater
contaminant concentrations In
groundwater below the Former
Landfill. Institutional controls will
further prevent onslte exposure.
chemical'speclflc ARARs
apply because media are
within 10** to 10*° risk range.
required by EPA's
Presumptive Remedy.
Expected to be In compliance
with action- and locaUon-
speclfic ARARs. No
chemical-specific ARARs
apply because media are
within to*4 to ltV° risk range,
required by EPA's
Presumptive Remedy.
the Integrity of the cap.
Reduction of residual risk
from direct contact.
Reduces future potential for
groundwater contamination
by reducing Infiltration.
Improved reliability over no
action. Requires long-term
maintenance to maintain
the Integrity of the cap.
New revegetatlve cover will
facilitate long-term
maintenance of the cover.
Reduction of residual risk
from direct contact.
Reduces future potential for
groundwater contamination
by reducing Infiltration.
A treatment technology Is
not Included as part of
this alternative.
workers through Increased dust
and potential for VOC Inhalation.
Proper dust control and air
monitoring during construction
will mitigate risk. Limited
community Impact through
Increased dust and noise from
construction activities. Truck
traffic Introduces risk for
vehicular accidents.
Less ttian nine months required to
Implement the components of this
alternative. Potential risk to
workers through Increased dual
and potential for VOC Inhalation.
Proper dust control and air
monitoring during construction
will mitigate risk. Limited
community Impact through
Increased dust and noise from
construction activities. Truck
(raffle Introduces risk for
vehicular accidents.
Implamentable
fl ,800,000
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Iota
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TabU 2.8(eontlniMd)
Alternative
Alternative 4 • Regrade and
Devegalale Landfill Cover
wllh Vapor Extraction
Ovtrell
Protection of H.rnaa Health aad
Am Environment
Reduces offslle exposure through
limited source remove! using vapor
extraction In the vadose zono
below the landfill contents.
Improvements to the existing cap
reduce the risk of exposure to the
landfill contents and may reduce
leaching of contaminants to
Rroundwater through decreased
Infiltration. Groundwaler
monitoring will provide protection
of human health and the
environment by essesslng any
changes In groundwater
contaminant concentrations In
groundwaler below the Former
Landfill. Institutional contents will
further prevent onslta exposure.
Compline* wllh ARARi
Expected to be In compliance
with action- and location-
specfflc ARARs. No
chemical-specific ARARs
apply because media are
within 10 ' to 10* risk range.
required by EPA's
Presumptive Remedy.
Long-term EflWllveaeei
•nd Permanenoi Redaction of MTV
Provides unproved Mobility and volume of
reUeblllty over no action. contaminants In the
Requires long-term vadose zone may be
maintenance to maintain reduced.
the integrity of the cap.
Reduction of residual risk
from direct contact.
Reduces future potential for
groundwater contamination
by reducing Infiltration and
providing limited source
removal In the vadose zone.
Short-ten EAVtlveiMM lewkneatabUltr
Less than nine months required to fmplementable
implement the components of this
alternative. Installation of vapor
extraction wells through landfill
poses potential risk to workers
due to UXO In landfill. Potential
risk to workers through (1) drilling
activities through landfill contents
and (2) Increased dust and
potential for VOC Inhalation.
Performing UXO clearance before
drilling; proper dust control, and
air monitoring during
construction should mitigate risk.
Limited community Impact
through Increased dust end noise
from construction activities.
Truck traffic Introduces risk for
vehicular accidents.
NetPnml
Worth Cost
($1
11,200,000
ARAR Applicable or nievani and appropriate raqulnment
EPA U.S. Environmental Protection Agency
MTV Mobility, toxlclty. and volume
UXOUnexploded ordnence
VOC Volatile organic compound
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a of 2
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Table 2.6 Estimated Capital Cost, Operation and Maintenance Cost, and
Net Present Worth
Alternative
1
2
3
4
Estimated
Capital Cost
($)
0
2,800,000
3,400,000
3,700,000
Estimated Annual
O&MCost
($)
70,000
260,000
220,000
290,000
Net Present
Worth*
($)
1,100,000
6,800,000
6,800,000
8,200,000
O&M Operation and maintenance
* Net present worth calculated using a 5 percent discount rate and a 30-year planning horizon.
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Table 2.7 Estimated Cost Summary of Selected Remedy •
Regrade and Revegetate Landfill Cover
Capital Cost
Direct Capital Cost
Regrade and Revegetate Landfill Cover $2,034,000
Landfill Improvements $25,000
Landfill Gas Monitoring Probes and Passive Gas Venting System $ 51.000
Subtotal - Estimated Direct Capital Cost $2,110,000
Indirect Capital Cost
Contingency (30 percent) $633,000
Engineering and Design (10 percent) $211,000
Contractor Overhead and Profit (10 percent) $211,000
Construction Management (10 percent) $ 211.000
Total - Estimated Capital Cost $3.400.000
Annual O&M Cost
Institutional Controls $5,000
Groundwater Monitoring $46,600
Cap Maintenance $87,500
Landfill Gas Monitoring and Venting $ 30,000
Subtotal - Estimated O&M Cost $169,000
Contingency (30 percent) $ 51.000
Total - Estimated Annual O&M Cost S220.000
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Pacific Ocean
1
y\.f/ Dike- Sx'fe
Schofield / \y/ impounded jX//|
Army Barracks V"// Water Body Y//
Main Post ^s s s ./ xx1
Explanation
Boundary between groundwater bodies
^^| Schofield Army Barracks
jU| Basal Water Body
|^5$<1 Schofield High-level Water Body
Y//\ Dike-impounded Water Body
|\\S1 Groundwater dam
A A'
*? i Generalized cross section line
Scale
5
10
Miles
Note: Modified from Dale and Takasaki, 1976
and Mink and Lau, 1987
Cross sections are shown in Rgure 2.5.
Harding Lawson Associates
Engineering and
Environmental Services
Prepared for:
U.S. Army Environmental Center
Aberdeen Proving Ground, Maryland
Schofield Army Barracks,
Island of Oahu, Hawaii
Figure 2.1
Regional Groundwater Systems
of Oahu, Hawaii
-------
Walalua
Basal Water
Body
\
Honolulu-Pearl Harbor
Basal Water Body
$ 2000 -
1600-
Walahole Transmission
Tunnel
Schofleld High-level
^ike-lmpqundecl
Herding Lows on Associates
Engineering and
Environmental Sen/Ices
Explanation
Low-permeablllty rock
| | Fresh groundwater
|y£&{ Saline groundwater
t Qroundwater (low line
4r (generalized direction)
Scale
3
Miles
s: Cross-section lines are shown In Figure 2.4.
Modified (rom Dale and Takasakl, 1976
Prepared for:
U.S. Army Environmental Center
Aberdeen Proving Ground, Maryland
Schofleld Army Barracks,
Island of Oahu, Hawaii
Figure 2.2
Regional Hydrogeologlc Cross Sections
A-A1 and B-B1
-------
Explanation
' Contours showing surface elevation
(in feet above mean sea level)
Surface-water drainage, may be
intermittent
Approximate
Landfill Outline
Underground
Fires
Base map modifiedlrom Kennedy Engineering, 1980a
Harding Lawson Associates
Figure 2.3
Pre-closure Landfill Features
Prepared for:
U.S. Army Environmental Center
Aberdeen Proving Ground, Maryland
Engineering and
Environmental Services
Schofield Army Barracks,
Island of Oahu, Hawaii
-------
Explanation
Contours showing surface elevation
(in feet above mean sea level)
Surface-water drainage, may be
intermittent
600
Scale in feet
Base map modified from Kennedy Engineering, 1980a
Harding Lawson Associates
Engineering and
Environmental Services
Prepared for:
U.S. Army Environmental Center
Aberdeen Proving Ground, Maryland
Schofield Army Barracks,
Island of Oahu, Hawaii
Figure 2.4
Pre-closure Landfill Fill Areas
-------
Explanation
TCE concentration in ppm by volume
,0564 soiHias sample location 1933
0001 TCE concentration in pom by volume
soiHjassampto location 1991
Sol-gas sample locations 1991 and 1993
Not detected. Anaytiol detection
imitki 1S9I was 0.0005 ppm by votinw
using an electron caplure detector
(ECD). Analytical SeleOxjn knit in 1993
was 0.010 ffn by volune using an
•lectiditic conductivity detector (ELCO).
Soil boring location
Soiborinoylyunelerlocalion
TCE ii sol gas
Anomaly type A
inctcative ol domestic waste
Area of subsidence observed
in the lieM
0 ISO 300
Scale in leet
Prepared for:
U.S. Army Environmental Center
Aberdeen Proving Ground, Maryland
Schofield Army Barracks, Island of Oahu, Hawaii
Figure 2.5
Soil Gas TCE Concentrations
Operable Unit 4
-------
OTlf SEOOI Suriace-water/sednnant sampto location
and designation
Monitoring wel location and designation
Sod boring location and designation
Soil borinolysimeler location and designation
Gas monitoring we* location and designation
Prepared for:
U.S. Army Environmental Center
Aberdeen Proving Ground, Maryland
Schofield Army Barracks, Island of Oahu, Hawaii
Figure 2.6
Boring, Lysimeter, Monitoring Well, and
Surface-Water and Sediment Sampling Locations
Operable Unit 4
-------
Schofield Army Barracks
Main Post
Schofield ^rmy Barracks
Forest Reserve x
Explanation
Kolekole
Pass
Approximate Regional Groundwater
Flow Directions
*\
\.
MW-4-2A Monitoring Well (Army Number)
/ • 3-31 03-01 Monitoring Well (State of Hawaii Permit Number)
* _
i | I Landfill
i «i«.«*
• '
"~-
. Site boundary
Highway
Road or street
0 2000 4000
Scale in feet
Harding Lawson Associates
Engineering and j
Environmental Services
• --- Wheeler Army Airfield boundary
_.-- — Surface-water drainage, maybe intermittent
Prepared for:
U.S. Army Environmental Center
Aberdeen Proving Ground, Maryland
Schofield Army Barracks,
Island of Oahu, Hawaii
Figure 2.7
Conceptual Groundwater
Monitoring Network
-------
Prepared for:
U.S. Army Environmental Center
Aberdeen Proving Ground, Maryland
Schofield Army Barracks, Island of Oahu, Hawaii
Figure 2.8
As-Built Drawing for Former Landfill
Operable Unit 4
-------
nly consHucOon and demolition debris:
appears to haw been dunped along edge
of slope: does not appear to be part ol
may MWIVTP debris.
Approximate Iccafion ol emosed
«a»e observed along lideSopV
•|»m,
become eiposed during excarabon d
tonw malenal; generally same l
ol burning raluse Iran landfn lire
Prepared for:
U.S. Airiy Environmental Center
Aberdoen Proving Ground, Maryland
Schofield Army Barracks, Island of Oahu, Hawaii
Figure 2.9
Plan View of Existing Cover
on Former Landfill
Operable Unit 4
-------
GMW-5
Explanation
G>s Monitoring Well
Location and Designation
Chain** Fence
;: B«fn
Brushline
Access Road
Mstal Oebtis (observed)
Wood Debris (observed)
Bieak in Slope
Topographic Slope Direction
Interpreted extent ot Landfill based on EM
Conductivity Measurements Greater tnan
50mmrios/m
Anomaly Type A
Indicative of Domestic Waste
Area ol Subsidence Observed
in w Field
Prepared for:
U.S. Army Environmental Center
Aberdeen Proving Ground, Maryland
Schofield Army Barracks, Island of Oahu, Hawaii
Rgure2.10
Location of Existing Gas Monitoring Wells
Operable Unit 4
-------
Proposal land gas monrnxing vwls location
TCE Concentration in ppm by volume
»*gai sample location 1993
ri in ppm by volume
sol-gas sample location 1991
TCEConcMntnU993
TCE Concentration 1991
Soityas sampl* locations 1991 and 1993
Not detected. AnalylicaJ detection
Unit in 1991 was 0.0005 ppm by volume
using an electron captuie detector
(ECO). Analytical detection knit in 1993
was 0.01D ppm by volume using an
electronic conduaivity detector (ELCD).
SoJ bonng location and designation
Anomaly type A.
indicative ol domestic waste
Area ol subsidence observed
in the field
Prepared for:
U.S. Army Environmental Center
Aberdeen Proving Ground, Maryland
Schofield Army Barracks, Island of Oahu, Hawaii
Figure 2.11
Conceptual Layout of Perimeter
Landlill Gas Monitoring Wells
Operable Unit 4
-------
Prepared for:
U.S. Army Environmental Center
Aberdeen Proving Ground, Maryland
Schofield Army Barracks, Island of Oahu, Hawaii
Location of Potential Hot Spot .
Operable Unit 4
-------
Explanation
Existing SVE mil
Proposed SVE wtfl
So* boring loolion «nd dMgnilion
Anomaly type A.
hdkative of domulic W
Area ol xtxOenx Oxmtt
•KieSekJ
Prepared for:
U.S. Army Environmental Center
Aberdeen Proving Ground, Maryland
Schofield Army Barracks, Island of Oahu, Hawaii
Figure 2.13
Conceptual Layout of SVE System
Operable Unit 4
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3.0 RESPONSIVENESS SUMMARY
1
3.1 Overview
This section provides a summary of the public comments and concerns regarding the OU 4 Proposed
Plan at Schofield Barracks, Island of Oahu, Hawaii. At the time of the public review period, the Army
had selected Alternative 3, Maintenance and Revegetation of the Landfill Cover, as the preferred
alternative for the OU 4 Former T-aTv^fiH Verbal comments were received and addressed during the
public meeting. On the basis of the lack of written comments received, the Army's Proposed Plan was
generally accepted by the public.
3.2 Background en Community Involvement
The Army has implemented a progressive public relations and involvement program for environmen-
tal 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
*r
•^ results, proposed work, and potential remedial actions. The Army distributed over 50 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 4 FS and Proposed
Plan from April 11 through May 11,1996. 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. The
meeting was held on May 1,1996, at 7:00 p.m. in the Hale Koa at Wahiawa District Park,
1139 A Kilani Avenue, Wahiawa, Hawaii.
r
v-
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Responsiveness Summary
No written comments were received from the public regarding the OU 4 Proposed Plan during public
comment period.
3.3 Summary of Comments Received During Public Comment Period and
Department of the Army Responses
No written comments were received from the public regarding the OU 4 Proposed Plan.
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4.0 ACRONYMS
1,1,1-TCA 1,1,1-Trichlorpethane
1,2-DCE 1,2-Dichloroethene
ARAR Applicable or relevant and appropriate requirement
Army U.S. Department of the Army
BTEX Benzene, toluene, ethylene, and xylenes
bgs Below ground surface
B WS Board of Water Supply
CO* Carbon tetrachloride
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act
cfm Cubic feet per minute
CFR Code of Federal Regulations
COPC Chemical of potential concern
DERP Defense Environmental Restoration Program
DOD U.S. Department of Defense
DOH Department of Health
EIA Environmental Impact Assessment
EPA U.S. Environmental Protection Agency
EPC Exposure point concentration
EP TOX Extraction procedure toxicity test
ERA Ecological risk assessment
ESE Environmental Science and Engineering
EFA Federal Facility Agreement
FS Feasibility study
GMW Gas monitoring well
HAR Hawaii Administrative Rules
HLA Harding Lawson Associates
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0408071296 ROD
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Acronyms
HRA
IRP
LPG
MCL
•mtn
MSL
MSWLF
NCP
NGVD
NPDES
NPL
O&M
ou
PA/SI
PAH
PCB
PCE
ppbv
ppm
PRG
RBSC
RCRA
RI
RME
KMT
ROD
SAP
Health Risk Assessment
Installation Restoration Program
Landfill gas
Maximum contaminant level
Millimeter
Mean sea level
Municipal Solid Waste Landfill
National Oil aT"^ Hazardous Substances Pollution Contingency Plan
National Geodetic Vertical Datum of 1929
National Pollutant Discharge Elimination System
National Priorities List
Operations and maintenance
Operable unit
Preliminary assessment/site investigation
Polynuclear aromatic hydrocarbon
Polychlorinated biphenyl
Tetrachloroethene
Parts per billion volume
Parts per million
Preliminary remediation goal
Risk-based screening concentration
Resource Conservation and Recovery Act
Remedial investigation
Reasonable maximum exposure
R.M. TowiH Corporation
Record of Decision
Sampling and Analysis Plan
Harding Lawson Associates
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Actonyins
SARA
Schofield Barracks
SVE
SVOC
TAMC
TCE
TEPS
TVH
USAEC
USAPEHEA
USASCH
UXO
VC
VOC
wwn
Mgfl
Superfund Amendments and Reauthorizan'on Act of 1986
Schofield Army Barracks
Soil vapor extraction
Semivolatile organic compound
Tripler Army Medical Center
Trichloroethene
Total Environmental Program Support
Total volatile hydrocarbons
U.S. Army Environmental Center
U.S. Army Pacific Environmental Health Engineering Agency
U.S. Air Support Command Hawaii
Unexploded ordnance
Vinyl chloride
Volatile organic compound
World WarH
Micrograms per liter
Micrograms per cubic meter
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4-3
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S.O REFERENCES
Asquith, G. 1982. Basic well log analysis for geologists: American Association of Petmlenm
Geologists.
Ecology and Environment, lac. 1981. Task report to USEPA, field investigations of uncontrolled
hazardous waste sites, FIT project Site Inspection Report, Schofield Barracks I-anrifm, Schofield
Army Barracks, Oahu, Hawaii, TDD# F-9-8009-16, to Mr. Robert M. Mandel, January 13.
Environmental Science & Engineering, Inc. 1984. Installation assessment of U.S. Army Support
Command, Hawaii Installations - Vol. E: Schofield Barracks and Pohakuloa Training Area, Kilauea
Military Camp, Makua Military Reservation, and Kipapa Ammunition Storage Sites, Hawaii. Report
No. 338, May.
Giambelluca, T.W., MA. Mullet, 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 preliminary assessment/site investigation report for operable
units I, 2, and 4, Schofield Army Barracks, Island of Oahu, 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 4 phase I remedial investigation,
Schofield Army Barracks.
. I995a. Final sampling and analysis plan for operable unit 4 phase H 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
of Oahu, Hawaii, April.
. 1995c. Final feasibility study report for operable unit 4, Schofield Army Barracks, Island of
Oahu, Hawaii, December.
Kennedy Engineers. 1980a. Closure of existing landfill for Department of the Army, Pacific Ocean
Division, Corps of Engineers. Sanitary TjmHftll Study, Schofield Barracks, Oahu, Hawaii, November.
. 1980b. Solid and hazardous waste disposal plan for Department of the Army, Pacific Ocean
Division, Corps of Engineers. Sanitary T-anrifm Study, Schofield Barracks, Oahu, 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 quality engineering
special study (W2) 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. 1993a. Presumptive Remedy for CERCLA Municipal Landfill
Sites. September.
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References
. 1993b. Registration elifflbility decision (RED): glyphosate. PB94-127917, September.
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
SYNOPSIS OF COMMUNITY RELATIONS ACTIVITIES
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 finalised 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.
April 11 through May 11,1996 - Schofield Barracks conducted a public review period for the
Proposed Plan for Operable Unit 4.
May 1,1996 - Schofield Barracks and the AEC conducted a public meeting to present the Operable
Unit 4 Proposed Plan and solicit public comments.
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