PB97-964502
                                 EPA/541/R-97/032
                                 November 1997
EPA  Superfund
       Record of Decision:
       Schofield Barracks (US Army),
       Operable Unit 2,
       Oahu, HI
       2/7/1997

-------
  U.S. Army
Environmental
    Center
                     Final Record  of Decision
                     for Operable  Unit 2
                     Schofield Army  Barracks
                     Island of Oahu,  Hawaii
                     Prepared by:

                     Harding Lawson Associates
                     707 Seventeenth Street, Suite 2400
                     Denver, Colorado 80202
235 Pearlridge Center Phase
98-1005 Moanalua Road
Aiea, Hawaii 96701
                     August 12,1996
                     Prepared for:

                     U. S. Army Environmental Center
                     Aberdeen Proving Ground, MD 21010-5401
                     Contract No. DAAA15-91-D-0013
                     Delivery Order DA03

-------
                               DEPARTMENT OF THE ARMY
                       HEADQUARTERS. UNITED STATES ARMY GARRISON. HAWAII
                             SCHORELD BARRACKS. HAWAII 96857-5000

         REPLY TO
         ATOaioNOF                                                           2 5 SEP  1996
Directorate of Public Works
Mr. Mark Ripperda
Remedial Project Manager, H-9-4
U.S. Environmental Protection Agency
Region IX
75 Hawthorne Street
San Francisco, California 94105-3901

Dear Mr. Ripperda:

    The Final Record of Decision for Operable Unit 2 is hereby transmitted to you. The Army has
approved this document and requests U.S. Environmental Protection Agency concurrence by signing on
sheet 1-5 of said document. Another copy of this document has been sent to the Department of Health,
State of Hawaii for their concurrence.  Upon concurrence, request that the original signature sheet be
transmitted to the Army for reproduction and distribution of the completed document. The original
signature sheets will be sent back to your office upon completion of that function.

    If you have any questions, please contact Mr. Jon Fukuda, Environmental Division, (808) 656-6790,
or Mr. James Daniel, U.S. Army Environmental Center, (410) 671-1501.

                                         Sincerely,
                                           ennis J. Fontana
                                         Colonel, U.S. Army
                                         Director of Public Works
Enclosure

-------
Final Record off Decision
for Operable Unit 2
Schofield Army Barracks
Island off Oahu, Hawaii
Prepared for

U.S. Army Environmental Center
Installation Restoration Division
HLA Project No. 33537 07.04.00
Contract DACA31-94-D0069
Delivery Order No. 0004
August 12, 1996

        Harding Lawson Associates
        Engineering and Environmental Services
        707 Seventeenth Street Suite 2400
        Denver, CO 80202 - (303) 292-5365
                                                          Recycled Paper

-------
Environmental Services Program Support
  Final Record of Decision for Operable Unit 2
Schofield Army Barracks, Island of Oahu..Hawaii
              August 12, 1996
     Contract Number DACA31-94-D0069
          Delivery Order No. 0004
        Report Preparation Team:
            Catherine Armstead
            Laura Hollingsworth
                Neil Myers

-------
                                        CONTENTS



1.0    DECLARATION	1-1

       1.1    Site Name and Location	.-.	1-1

       1.2    Statement of Basis and Purpose	1-1

       1.3    Assessment of the Site	1-2

       1.4    Description of the Selected Remedy	1-2

       1.5    Declaration Statement	1-2

2.0    DECISION SUMMARY	2-1

       2.1    Schofield Barracks Site Location and Description	2-1

       2.2    Schofield Barracks Installation Operational History	2-2

       2.3    Enforcement and Regulatory History	2-3

       2.4    Operable Unit 2 Site Selection History	2-4

       2.5    Operable Unit 2 Site Description	2-5

       2.6    Highlights of Community Participation	2-5

       2.7    Scope and Role of Operable Unit	2-7

       2.8    Site Characterization	2-8
             2.8.1     Nature and Extent of Contamination	2-8
             2.8.2     Contaminant Fate and Transport	2-9

       2.9    Summary of Site Risks	2-10

       2.10  Description of Alternatives	2-13
             2.10.1    Alternative 1 - No Action/Institutional Controls	2-16
             2.10.2    Alternative 2 - Air Stripping	2-16
             2.10.3    Alternative 4 - Ozone/Hydrogen Peroxide Treatment	2-18

       2.11  Summary of Comparative Analysis of Alternatives	2-19
             2.11.1    Overall Protection of Human Health and the Environment	2-20
             2.11.2    Compliance with ARARs	2-20
                      2.11.2.1 High Groundwater Volume	2-21
                      2.11.2.2 Potential Impacts to Basal Aquifers	2-21
                      2.11.2.3 Protectiveness of Wellhead Treatment	2-22
             2.11.3    Long-term Effectiveness and Permanence	2-22
             2.11.4    Reduction in Toxicity, Mobility, and Volume	2-22
             2.11.5    Short-term Effectiveness	2-23
             2.11.6    Implementability	2-23
             2.11.7    Cost	2-23
             2.11.8    State Acceptance	2-23
             2.11.9    Community Acceptance	2-24

33537 07.04.00                                        Harding Lawson Associates              i
0318120396 ROD

-------
       2.12  Selected Remedy	2-24

       2.13  Statutory Determinations	2-25

3.0    RESPONSIVENESS SUMMARY	3-1

       3.1   Overview	3-1

       3.2   Background on Community Involvement	3-1

       3.3   Summary of Comments Received During Public Comment Period and Department
            of the Army Responses	3-2

4.0    ACRONYMS	4-1

5.0    REFERENCES	5-1

TABLES

2.1    Summary of Noncarcinogenic and Carcinogenic Risks for OU 2
2.2    Location-specific Applicable or Relevant and Appropriate Requirements for Schofield Barracks
       OU2
2.3    Chemical-specific Applicable or Relevant and Appropriate Requirements and
       To-Be-Considered" Guidance for Cleanup of Groundwater at Schofield Barracks OU 2
2.4    Action-specific Applicable or Relevant and Appropriate Requirements for OU 2 at, Schofield
       Army Barracks, Hawaii
2.5    Preliminary Estimated Influent Chemicals of Concern Concentrations and Proposed Treatment
       Standards for Schofield Army Barracks OU 2
2.6    Summary of Comparative Analysis of Alternatives
2.7    Calculations for Estimated Maximum Trichloroethene and Carbon Tetrachloride Vapor
       Discharge from Alternative 2 (Air Stripping Treatment)
2.8    Summary of Estimated Costs for Remedial Action Alternatives at Schofield Army Barracks for
       OU2
2.9    Estimated Cost Summary of Selected Remedy - Air Stripping

FIGURES

l.l    Location Map of Schofield Barracks
1.2    Site Map of Schofield Barracks
2.1    Regional Groundwater Systems of Oahu, Hawaii
2.2    Regional Hydrogeologic Cross Sections A-A' and B-B'
2.3    Trichloroethene Isoconcentration Map
2.4    Proposed Long-term Groundwater Monitoring Network
2.5    Alternative 2 Process Flow Diagram of Air Stripping OU 2 Groundwater Treatment
2.6    Alternative 4 Process Flow Diagram of Ozone/Hydrogen Peroxide Oxidation System for OU 2
       Groundwater Treatment

APPENDIXES

A      SYNOPSIS OF COMMUNITY RELATIONS ACTIVITIES
B      COMMENTS RECEIVED DURING PUBLIC COMMENT PERIOD AND ARMY RESPONSES
C      ANALYSIS  OF THE IMPACT OF TRICHLOROETHENE ON CARBON USAGE
fi            Harding Lawson Associates                                      33537 07.04.00
                                                                           0318120396 ROD

-------
Declaration	



                                    1.0 DECLARATION



This Final Record of Decision (ROD) for Operable Unit (OU) 2 has been prepared by Harding

Lawson Associates (HLA) for the U.S. Army Environmental Center (USAEC) under Delivery

Order No. 0004 of the Total Environmental Services Program Support (ESPS) Contract

DACA31-94-D-0069. This report documents the remedial action plan for OU 2 at Schofield

Army Barracks (Schofield Barracks), Island of Oahu, Hawaii.



1.1           Site Name and Location

Schofield Barracks is located in the north-central plateau of the Island of Oahu in the State of Hawaii

(Figure 1.1). The Schofield Barracks installation is approximately 22 miles northwest of the City of

Honolulu. The closest municipality is Wahiawa, which is immediately north of Schofield Barracks.

The installation is divided into two sections, the East Range and the Main Post (Figure 1.2),

encompassing a total area of approximately 27.7 square miles. Wheeler Army Airfield (Wheeler) lies

between and to the south of the two Schofield Barracks sections.




Operable Unit 2 addresses the contaminated groundwater system beneath Schofield Barracks.



1.2           Statement of Basis and Purpose

This decision document (ROD) presents a response action for OU 2, the contaminated groundwater

system beneath Schofield Barracks.  This action was selected in accordance with the Comprehensive

Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), as amended by the

Superfund Amendments and Reauthorization Act of 1986 (SARA) and, to the extent practicable, the

National Oil and Hazardous Substances Pollution Contingency Plan (NCP). This ROD explains the

basis for selecting the response action for OU 2.  Information supporting the selected response action is

contained in the Administrative Record for Schofield Barracks.
33S3707.04.oo                                      Harding Lawson Associates            1-1
0308120396 ROD

-------
Declaration
1.3          Assessment of the Site

Actual or threatened releases of hazardous substances from this site/ if not addressed by implementing

the response action selected in this ROD, may present a current or potential threat to public health,

welfare, or the environment.


1.4          Description off the Selected Remedy

The function of OU 2 is to address base-wide groundwater contamination. The selected remedy

provides protection of human health and the environment by reducing potential risks associated with

domestic use of the contaminated groundwater.  The remedy includes the following components:


 •     Continued treatment for contaminants of concern (COCs) present in extracted groundwater at
       the Schofield Barracks Supply Wells by air stripping at the wellhead followed by discharge of
       the treated water to the distribution system

 •     The Army must consult with EPA and the State of Hawaii prior to abandoning the Schofield
       Barracks water supply wells, because production at these wells may help to control plume
       migration

 •     Long-term sampling and analysis of water supply wells, agricultural wells, and monitoring
       wells in the region

 •     Implementation of the contingency of wellhead treatment on any water supply wells that are
       impacted by the plume from Schofield Barracks above one-half of the Maximum Contaminant
       Level (MCL) as established under the Safe Drinking Water Act (SDWA)

 •     Upgrade the treatment system or pay any incremental costs for treatment caused by
       contamination from Schofield Barracks at wells that already have a treatment system in place

 •     Conduct five-year site reviews with the State of Hawaii Department of Health (DOH) and the
       U.S. Environmental Protection Agency (EPA).


The details of the monitoring plan, evaluation process for implementation of wellhead treatment, and

description of conditions at existing water wells may be found in the Final Operation and Maintenance

and Long-Term Groundwater Monitoring Plan for Operable Unit 2, Schofield Army Barracks, which is an

addendum to this ROD. The EPA and DOH concur with the above selected response actions (remedy).


1.5           Declaration Statement

The selected remedy is protective of human health and the environment, and is cost effective, but does

not meet the applicable or relevant and appropriate requirement (ARAR) for restoration of groundwater
1*2           Harding Lawson Associates                                        3353707.04.00
                                                                              0308120396 ROD

-------
                                                                                 Declaration
to MCLs under the SDWA. An ARAR waiver for technical impracticability (TI waiver) is being invoked


for this ROD, as described in the Justification for Technical Impracticability Waiver at Schofield Barracks


for the Ground Water Record of Decision. The TI waiver justification is part of the Administrative


Record for Schofield Barracks.




The selected remedy complies with CERCLA in that this action is a permanent solution to the


maximum extent practicable or necessary for OU 2 and satisfies the NCP preference for treatment as a


principal element of the remedy. A TI waiver is necessary for this action, however, because


contaminants will remain in the groundwater at levels of concern for an undetermined period of time.


Therefore, a groundwater monitoring program will be implemented to assess changing aquifer


conditions and to track potential movement of the TCE/carbon tetrachloride plumes. A site review will


be conducted once every five years until groundwater remediation goals, which are the SDWA MCLs,


are achieved in the groundwater system.
3353707.04.oo                                       Harding Lawson Associates            1-3
0308120496 ROD

-------
 Declaration
                     Frank L. Miller, Jr.
                     Major General, U.S A.
                     Assistant Chief of Staff for Installation Management
                     U.S. Army
3353707.04.oo                                       Harding Lawcon Associates            1-4
0308120396 ROD

-------
Declaration
                   Dan  Opalski~ f ~       .
                   Chief,  Federal Facilities  Cleanup Branch
                   EPA, Region 9
33537 07.04.00                                    Harding Lawson Associates          1.5
0308120396 ROD

-------
Declaration
                     Lawrence Mike, M.D.
                     Director of Health
                     State of Hawaii
33S3707.04.oo                                      Harding Lawson Associates            1-6
0308120396 ROD

-------
                                                 Peart
                                                 Harbor
                                                                    Honolulu
               Explanation
               Scfwftetd Barracks
               Cities, towns
               Rwers, streams
               Higtiways, roads
         Sources: US. Army Pacific Environmental Heatti
         Engineering Agency (USAPEHEA). 1977.
         642d Engr.eer Battalion (TOPO). 1977.
         ESc. 1384.
                              Seate
                              5
                                                                   10
                                                                      Mies
                                                                                        10
                                                                                          Kaometers
Harding Lawson Associates
Engmaonng and
Prepared for
U.S. Army Environmental Center
Aberdeen Proving Ground. Van/land
Schofield Barracks. Island of Oahu. Hawaii
Figure 1.1
Location Wap of Schcfieid Barracks

-------
      Explanation
     Wt**** Ainty Avfiild tnundvy
(icgas±
 "^
                                                                                                                                               Piepated lot:
                                                                                                                                               U.S. Aimy Envlfonmental Cental
                                                                                                                                               AMidMn Prooing Oiound. M«iyKnd


                                                                                                                                               Schofield Aimy Ban»c*». Island ol Oahu, Hawaii
                                                                                                                                               Flgw* 1.2

                                                                                                                                               Site Map ol ScnofieM Bairacka

-------
                                 2.0 DECISION SUMMARY



This section provides an overview of the site-specific factors and analyses that led to final remedy


selection. This overview includes a general site description, site history, enforcement and regulatory


history, highlights of community participation, scope and role of OU 2, site characteristics, summary of


site risks, and documentation of significant changes to these elements. Much of the information


presented in this section was derived from previous investigations performed by the U.S. Department of


the Army (Army) and its contractors and has been previously presented in more detail in the


Preliminary Assessment/Site Investigation (PA/SI) Report (HLA, 1992a), Final Work Plan for Schofield


Army Barracks Remedial Investigation/Feasibility Study (RI/FS) (HLA, 1992b), the Final OU 2 Phase I


and Phase n Sampling and Analysis Plans (SAPs) (HLA, 1993 and I995c), the Final OU 2 RI Report


(HLA, 1996a), and the Draft Feasibility Study for Operable Unit 2 (HLA, 1996b).



2.1           Schofield Barracks Site Location and Description


Schofield Barracks is located in central Oahu (Figure 1.1) within the physiographic province known as


the Schofield Plateau. Ground surface elevations range from approximately 700 feet (National Geodetic


Vertical Datum of 1929 [NGVD]) near the central portion of Schofield Barracks to approximately


4,000 feet (NGVD) near the western boundary of the Main Post in the Waianae Mountain Range. The


drainage divide of the Schofield Plateau runs roughly east-west through the center of the Main Post.


North of this divide, watercourses flow to the north and discharge into Kaiaka Bay at the town of


Haleiwa.  South of this divide, watercourses flow south and discharge into the West Loch of Pearl


Harbor. Narrow gulches dissect the plateau where streams have eroded the land surface.





The relatively flat Schofield Plateau was formed as basaltic lava flowed from the adjacent Koolau and


Waianae volcanoes to the east and west, respectively. The upper 100 to 200 feet of the basaltic bedrock


within the Schofield Plateau is weathered saprolite. The saprolite consists of soil (primarily fine-


grained materials including silt and clay) formed by in situ decomposition of the basaltic bedrock.  The


saprolite is underlain by relatively unweathered basaltic bedrock consisting of interbedded pahoehoe


and a'a lava flows. The lava flows are highly fractured with cinder and clinker zones.



33537 07.04.oo                                       Harding Lawson Associates            2-1
0308091796 ROD

-------
Decision Summary
Three types of groundwater systems have been identified in central Oahu:  (1) the Schofield High-level

Water Body, (2) basal groundwater, and (3) dike-impounded groundwater (Figures 2.1 and 2:2).  The

Schofield High-level Water Body is located beneath the Schofield Plateau, and subsequently, the site.

This water body is bound to the east and west by dike-impounded groundwater and to the north and

south by basal groundwater. Lower permeability rocks (possibly volcanic dikes and/or buried ridges)

structurally separate these groundwater systems from one another.  The Schofield high-level aquifer has

a high transmissivity and hydraulic conductivity.  The depth to groundwater at the site is

approximately 600 feet below ground surface (bgs) (approximately 270 feet above mean sea level [msl]).



The climate at Schofield Barracks, which is south of the Tropic of Cancer at approximately 21 degrees

north latitude, is characterized by moderate temperatures that remain relatively constant throughout the

year.  The average annual rainfall in the vicinity of Schofield Barracks is approximately 1.2 meters

(Giambelluca and others, 1986), more than half of which occurs during the rainy season from November

through February. Trade winds have an average speed of 12 knots and prevail from the northeast or

east approximately 70 percent of the time.



Because of the relatively large amounts of undeveloped land, combined with a relatively large amount

of vertical relief, Schofield Barracks is host to diverse and abundant flora and fauna. Undisturbed

natural vegetation at Schofield Barracks is found primarily in the steep gulches on the east and west

sides. These gulches support birds and other fauna and blocks of forestry plantings and dense

shrubbery growth.


2.2          Schofield Barracks Installation Operational History

Schofield Barracks was established in 1908 as a base for the Army's mobile defense of Pearl Harbor and

the Island of Oahu. It served as a major support facility during World War n (WWII) temporarily

housing more than one million troops. It also served as a support and training facility during the

Korean and Vietnam conflicts. Since the Vietnam conflict, it has served primarily as a training facility.
2-2           Harding Lawson Associates                                         33537 07.04.00
                                                                               0308091796 ROD

-------
                                                                         Decision Summary
Schofield Barracks is the Army's largest installation outside of the continental United States. It

currently serves as the home of the 25th Infantry Division (Light), whose mission is to be prepared to

respond to war at a moment's notice. Installation facilities include a medical facility, community and

housing support facilities, and transportation and repair facilities.



2.3          Enforcement and Regulatory History

TCE, a commonly used cleaning solvent, was detected in the Schofield Barracks water-supply wells in

1985. The source of the TCE contamination could not be identified. In September 1986, the Army

installed air-stripping treatment units to remove TCE from the Schofield Barracks domestic water

supply. In 1987, the EPA established an MCL for TCE of 5 micrograms per liter 0*g/l) in drinking water.

TCE has not been detected in Schofield Barracks' treated water supply at concentrations greater than

this EPA-established limit




As a result of the detection of TCE in the Schofield Barracks water-supply wells, Schofield Barracks was

placed on the National Priorities List (NPL) in August 1990. The NPL was developed by EPA to identify

sites that may present a risk to public health or the environment. Investigations conducted following

NPL listing also revealed carbon tetrachloride contamination in the groundwater beneath the Former

Schofield Barracks I-andfill; therefore, carbon tetrachloride contamination of the groundwater will be

addressed along with TCE under this ROD.




After Schofield Barracks was placed on the NPL, a Federal Facility Agreement (FFA) was negotiated

among EPA, the State of Hawaii, and the Army under CERCLA, Section 120. The FFA was signed by

the Army on September 23,1991, EPA on September 27,1991, and State of Hawaii on June 5,1996.

The FFA identified Schofield Barracks as being under the jurisdiction, custody, or control of the U.S.

Department of Defense (DOD) and subject to the Defense Environmental Restoration Program (DEEP).
33537 07.04.00                                      Harding Lawson Associates            2*3
0308091796 ROD

-------
Decision Summary
              Operable Untt 2 Stte Selection History

As a part of the FFA, the Army and regulatory agencies agreed to divide the program into subunits

called OUs to address potential areas of contamination at Schofield Barracks in an organized

This ROD addresses OU 2, which was established to address the contamination present in the

groundwater beneath Schofield Barracks.



During 1991, the Army began to investigate potential contaminant sources at Schofield Barracks

through implementation of a PA/SI as required by the FFA.  The objective of the PA was to identify

possible onpost and offpost groundwater contamination sources both at Schofield Barracks and the
                  •
surrounding study area. The PA consisted of the following three activities designed to collect

additional information regarding Schofield Barracks and nearby offpost communities:


•      Conduct an onpost records search of 10 onpost sites (including the Former Landfill) identified
       in the FFA  (EPA, State of Hawaii, and Army, 1991).

•      Survey and sample existing water-supply wells in the Schofield High-level Water Body.

•      Conduct an industrial activity survey of communities in the study area to identify potential
       offpost TCE sources.


The objective of the SI was to collect field data to assess potential sources of contamination at the

Former Laundry, the East Range Disposal Area, and the Former Landfill.



Results of the records search, industrial activity survey, well survey, and sampling were discussed in

detail in the PA/SI Report (HLA, 1992a). Given the results of the PA/SI, additional groundwater

investigations were recommended.



The investigation of groundwater contamination (OU 2) was conducted under a two-phase program

Phase I focused on collecting data on aquifer characteristics (regional and local) to provide a better

understanding of the aquifer behavior.  The specific goals of the Phase IRI are presented in the Final

SAP for OU 2 Phase I RI (HLA, 1993). The OU 2 Phase H investigation is based on results of the OU 2

Phase I investigation, the OU 1 investigation, the OU 4 Phase I investigation, and the refined site


2-4           Harding Lawson Associates                                        33537 07.04.00
                                                                              0308091796 ROD

-------
                                                                          Decision Summary
conceptual model. The results of the OU 2 Phase I and n investigations are presented in the Final OU 2


RI Report (HLA, 1996a).
              Operable Unit 2 Site Description


OU 2 consists of the groundwater beneath Schofield Barracks.  This groundwater is 550 to 650 feet bgs


and is part of the groundwater body known as the Schofield High-level Water Body. It is called a "high-


level" water body because the groundwater levels beneath Schofield Barracks are much higher than


groundwater levels in the nearby coastal areas because of underground geologic structures which act as


dams to groundwater flow.  Most of the groundwater beneath Schofield Barracks originates as rainfall in


the Koolau and Waianae mountain ranges to the east and west This rainfall seeps into the ground in


the mountain areas and moves through the subsurface eventually reaching Schofield Barracks. A small


amount of water also seeps into the ground in the Schofield Barracks area and reaches the underlying


groundwater. The groundwater beneath Schofield Barracks eventually flows into the coastal water


bodies to the north and south over the groundwater dams.





A source for the TCE in the groundwater beneath Schofield Barracks has not been identified; however,


it is likely that the substance migrated from a ground surface location through the soil and bedrock to


the underlying groundwater. The former landfill was identified as the source of the carbon


tetrachloride in the groundwater underlying that site. The Schofield Barracks water-supply wells are


currently extracting contaminated groundwater from the groundwater system (OU 2); however, all


contaminated water currently being pumped from the groundwater beneath Schofield Barracks is being


treated by an air-stripping treatment system, which removes the contamination to acceptable standards


before the water is distributed for human use.



2.6           Highlights of Community Participation


In an effort to involve the public, the Army has undertaken several public and community awareness


efforts including issuance of employee bulletins and post newspaper articles for Schofield Barracks


employees, media interviews, news releases, and meetings with local officials and neighborhood boards


for offpost residents. In addition, the Army has held public meetings, issued fact sheets, and



33537 07.04.oo                                       Harding Lawson Associates            2-5
0308091796 ROD

-------
Decision Summary
established an Army contact for the public at Schofield Barracks' Public Affairs Office.  Copies of work

plans, technical reports, fact sheets, and other materials related to the project are available for public

review at the following local repositories:


       Mililani Public Library
       95-450 Makaimoimo Street
       Mililani, Hawaii 96789

       Wahiawa Public Library
       820 California Avenue
       Wahiawa, Hawaii 96786

       U.S. Army Garrison, Hawaii
       Directorate of Public Works
       Building 105
       Wheeler Army Airfield. Hawaii 96857-5000

       State of Hawaii Department of Health
       Environmental Quality Control Office
       220 South King Street, 4th floor
       Honolulu, Hawaii 96813


On May 24,1996, the Army presented the Proposed Plan for OU 2 at Schofield Barracks to the public

for review and comment The Proposed Plan summarizes information collected during the OU 2 PA/SI

and RI and other documents in the Administrative Record for the Schofield Barracks that are available

at the above local repositories. In addition, the proposed plan summarizes the alternatives contained in

the FS and outlines the preferred alternative. Prior to the  public meeting copies of the Proposed Plan

were placed in the local repositories and a public notice was placed in the local newspapers advising

the public of its availability. Also, copies of the Proposed Plan were mailed directly to residents and

public officials on the Community Relations Plan mailing list.



Comments regarding the Proposed Plan were accepted during a 30-day public review and comment

period that began on May 24,1996. A public meeting was held on June 12,1996, at 1139A Kilani

Avenue, Wahiawa, Hawaii. At that time, the public had the opportunity to discuss the plan with the

Army, EPA, and the Hawaii Department of Health (DOH) and express concerns about the plan.  In

addition, written comments were accepted during the public comment period. Responses to comments

received during the public comment period are included in the Responsiveness Summary (Section 3.0),


2-6           Harding Lawson Associates                                        33537 07.04.oo
                                                                              0308091796 ROD

-------
                                                                        Decision Summary
which is part of this ROD. In addition, responses to the comments received during the public comment

period were sent directly to the individual commenter.  The public comment period, as discussed

above, is a continuation of the Army's commitment to community involvement in the Schofield

Barracks Installation Restoration Program (IRP) and is required by CERCLA.



This decision document presents the selected remedial action for OU 2 at the Schofield Barracks,

Hawaii, chosen in accordance with CERCLA, as amended by SARA, and to the extent practicable, the

National Contingency Plan. The decision for OU 2 is based on the Administrative Record.


2.7           Scope and Role of Operable Unit

The scope of OU 2 consists of the groundwater system beneath Schofield Barracks. The objectives of

the OU 2 program are to:


•      Assess the presence or absence of contamination within the groundwater system

•      Assess the extent of contamination if contaminants are present

•      Assess the risks to public health and the environment posed by contamination if contaminants
       are present

•      Identify and evaluate remedial alternatives for site cleanup if contaminants are present in levels
       that could endanger public health and the environment

•      Implement a preferred remedial alternative that assures protection of public health and the
       environment

                                                      V
OU 2 addresses the contamination present in the groundwater beneath Schofield Barracks. Potential

sources of contamination to the groundwater system are addressed in OU 1 and OU 4 (the Former

Landfill).  OU 3 addresses the potential presence of contamination at various other small sites on

Schofield Barracks. OU 2 is the only operable unit addressed in this ROD.



OU 2 addresses the principal threat to human health and the environment posed at this site by

minimizing human exposure to contaminated groundwater through treatment prior to its entering the

drinking water distribution system.
33537 07.04.oo                                       Harding Lawson Associates            2-7
0308091796 ROD

-------
PocWon Summary _


2.8           Stte Characterization

This section of the OU 2 ROD provides a summary of the results and data evaluation activities

undertaken as a part of the RI/FS for OU 2. Additional details regarding the results and evaluation of

data relevant to the groundwater system are presented in the OU 1, 2, and 4 PA/SI report (HLA,

119992a); Final OU 4 Phase H SAP (HLA, 1995a); the Draft OU 2 Feasibility Study Report (HLA, 1996b);

the Final OU 2 Remedial Investigation Report (HLA, 1996a); and the Final OU 1 RI Report (HLA,

1995b).  A summary of the nature and extent of contamination and contamination fate and transport is

provided in Sections 2.8.1 and 2.8.2, respectively.                               -
              Nature and Extent off Contamination

Groundwater was the only media investigated for OU 2. The only analytes detected above MCLs in the

groundwater system beneath Schofield Barracks and Wheeler were TCE, carbon tetrachloride,

antimony, and manganese. Contaminants were detected in two plume areas: (1) beneath the Former

Landfill and (2) beneath the Schofield Barracks East Range and Wheeler (East Range/Wheeler). The

horizontal extent of carbon tetrachloride, antimony, and manganese contamination, with the exception

of one detection of carbon tetrachloride at Well MW-2-3, was limited to the immediate vicinity of the

Former Landfill. The inorganic compounds antimony and manganese were detected above MCLs

inconsistently.  Because of this inconsistency and because these inorganic compounds were not

detected above MCLs during the most recent sampling event, the detections of antimony and

manganese above MCLs are believed to be anomalous.  Therefore, only TCE and carbon tetrachloride

were retained as chemicals to be addressed for the OU 2 FS. Figure 2.3 shows a contour map of the

horizontal extent of TCE greater than 5 jig/1 in the groundwater system beneath Schofield Barracks. The

data points in Figure 2.3 represent average concentrations of TCE in samples collected from the wells.

Figure 2.4 presents the detected organic compound analytical results from OU 2 samples for the four

sampling rounds. A more detailed explanation of the distribution of VOCs in groundwater beneath

Schofield Barracks is summarized in the OU 2 RI report.
2-8          Harding Lawson Associates                                        33537 07.04.00
                                                                             0308091796 ROD

-------
                                                                          Decision Summary
The vertical distribution of TCE in the Former Landfill area appears to be relatively uniform with depth

from the top of the aquifer (275 feet msl) to approximately 0 feet msl. Data are not available "for greater

depths in the Former Landfill area.  The vertical distribution of TCE in the East Range/Wheeler area

appears to increase with depth to about 195 feet msl and then decrease to below MCLs at approximately

5 feet msl.



Existing information indicates that ofisite wells have likely not been impacted by TCE or carbon

tetrachloride in levels above MCLs from either the Former Landfill area or the East Range/Wheeler area.

However, low concentrations (less than 5 pg/1) of TCE were detected in three ofisite wells located near

Kunia just southwest of Wheeler.
               Contaminant Fate and Transport

As indicated in the previous section, the contaminants designated as COCs for the OU 2 FS are TCE and

carbon tetrachloride. This section summarizes the fate and transport processes that affect current and

potential migration of these COCs through both the vadose zone and the ground-water system.



Physical and chemical mechanisms that impact the fate and transport of TCE and carbon tetrachloride

were evaluated for both the vadose zone and the saturated zone. Results of the vadose zone

investigations indicated the following:


•      The primary mechanism for contaminant transport in the vadose zone appears to be advecn've
       flow of water containing COCs in a dissolved phase (i.e., contaminants move along dissolved in
       the water).

•      The primary direction of COC movement in the vadose zone is vertical, therefore, little lateral
       spreading of contaminants in the vadose zone likely occurred.

•      It was determined that contaminant migration in the vadose zone likely occurred primarily in
       fractures or other remnant basaltic features in the saprolite zone, and that this migration
       occurred primarily during high-intensity infiltration events (high-rainfall events which resulted
       in surface ponding).

•      The rate of migration of COCs in the vadose zone may be reduced by adsorption of chemicals
       onto organic matter within the soil matrix (known as retardation). However, because of the low
       amount of organic matter in the vadose zone, this mechanism is not considered significant.


33S37 07.04.oo                                       Harding Lawson Associates            2-9
0308091796 ROD

-------
Decision Summary
•      The amount of COG reaching the water table may be reduced by biological degradation of the
       contaminant in the vadose zone. However, few data are available to evaluate the impact of
       degradation in the vadose zone, and thus this mechanism was not evaluated in detail.

•      Results of field testing and computer modeling indicate that TCE (the most widespread COG)
       could migrate through the vadose zone to the groundwater in approximately 10 years.


Results of the saturated zone investigations indicated the following:


•      On a regional scale (greater than approximately 500 lateral feet), the aquifer material (fractured
       basalt) appears to be hydraulically connected such that it behaves like porous aquifer material.
       Therefore, preferred contaminant pathways (such as large single fractures) do not appear to be a
       significant mechanism of offsite transport.

•      As in the vadose zone, the primary mechanism of transport appears to be advective water flow
       containing COCs in the dissolved phase and the direction of movement is primarily driven by
       the direction of groundwater flow.

•      Retardation and degradation may impact contaminant movement in the saturated zone.
       However, no data are available to evaluate whether these phenomena have any impact on
       migration within the saturated zone.

•      Results of computer modeling indicate that under the most conservative assumptions (no
       retardation or degradation), TCE concentration above the MCL could reach downgradient
       receptors (to the south) in approximately 100 years.


2.9           Summary of Site Risks

A baseline risk assessment was prepared to evaluate the potential human and ecological risks posed by

chemicals detected in the groundwater at OU 2. This baseline risk assessment is provided as

Section 7.0 in the Final OU 2 RI Report (HLA, 1996a). The data collected during Phase I and n of the RI

were used as the source for the analytical data for the human health risk assessment (HRA) and the

ecological risk assessment (ERA). Because OU 2 is limited to the groundwater at Schofield Barracks,

groundwater is the only medium of concern for this risk assessment. Additionally, the only

contaminated water currently being used as a public drinking water supply is extracted from the

Schofield water-supply wells. However, this water is being treated by an air-stripping treatment system

prior to distribution and use so that the water quality meets the federal SDWA MCLs for public water

supplies. Consequently, the risks presented in the HRA reflect untreated groundwater and not actual

current exposures.
2-10          Harding Lawson Associates                                         33537 07.04.00
                                                                               0306091796 ROD

-------
                                                                         Decision Summary
Two separate areas of concern were evaluated: (1) the Former Landfill area and (2) the East


Range/Wheeler area. The Former Landfill area was evaluated using the data from four existing


groundwater monitoring wells (Figure 2.3).  The East Range area was evaluated using data from


groundwater monitoring wells in the eastern portion of Schofield, in the Wheeler area, and the


Schofield Barracks water-supply wells.
Chemicals of potential concern (COPCs) were selected for risk assessment by comparing the
detected concentration to both the MCLs (primary or secondary) and the EPA Region IX PRG for


residential ingestion (EPA, 1995). If the maximum detected concentration exceeded the MCL, the


chemical was retained as a COPC. If an MCL was not available, the EPA Region IX PRG was used for


comparison. Four chemicals were initially retained as COPCs for the risk assessment: antimony,


carbon tetrachloride, manganese, and TCE. However, as discussed in Section 2.8.1, antimony and


manganese were detected inconsistently above MCLs and were not detected above MCLs during the


most recent sampling event, therefore the detections above MCLs are believed to be anomalous.


Therefore, only TCE and carbon tetrachloride were retained as COCs to be addressed in evaluating


remedial alternatives.





No current human populations with exposure to untreated groundwater were identified. Water


withdrawn from the Schofield Barracks water-supply wells is treated to achieve MCLs prior to


distribution and use. Therefore, the population of interest in the HRA is a future residential population,


both adults and children. Exposure pathways considered in the HRA are those commonly associated


with domestic use of water, namely ingestion of water, dermal contact with water, and inhalation of


volatile organic compounds (VOCs)  during water use. VOCs may volatilize from groundwater and


eventually diffuse into the ambient air and subsequently be inhaled by a receptor. However, the low


concentrations of VOCs in the groundwater (less than 100 parts per billion [ppb]), the depth to


groundwater (approximately 500 to 600 feet), complex hydrogeology, and the inherent uncertainties in


estimating these exposures preclude a quantitative evaluation of exposures related to soil gas.



33537 O7.04.oo                                      Harding Lawson Associates           2-1 1
0308091796 ROD

-------
Decision Summary
Potential exposures to humans were evaluated for both average case and reasonable maximum exposure


(RME) scenarios. Different exposure and chemical intake assumptions were used to represent the

average and RME scenarios.  Average and RME exposure point concentrations for COPCs in the

groundwater were estimated as the arithmetic mean and 95 percent upper confidence limit.


respectively, as recommended by EPA. Average and RME exposure point concentrations were

developed for (1) the Former Landfill area and (2) the East Range/Wheeler area.  Additionally, because

Schofield Barracks Water-supply Well No. 4 is most commonly used as the source of water for

distribution, the maximum TCE concentration detected in this well was evaluated as a separate source.




Carcinogenic health effects (expressed as risk) and noncarcinogenic health effects (expressed as hazard

indices [HI]) were  characterized by combining the estimated chemical intakes with the appropriate

toxicity factors (i.e., carcinogenic slope factors and noncarcinogenic reference doses). Only chronic

tenacity factors were used in the HRA. Oral toxicity factors were used to evaluate dermal exposures.

Table 2.1 presents the total carcinogenic and noncarcinogenic risks estimated for the adult and child

receptor for both the Former Landfill area and the East Range/Wheeler area.




The RME noncarcinogenic His exceed 1.0, which is the EPA benchmark for concern, for both the child

and adult resident for the Former Landfill area (maximum HI of 9.3, child receptor). However, the

majority of the estimated HI is a result of antimony detected in landfill wells.  Antimony was

inconsistently detected within a given well and between wells hi the Former Landfill area.  Because

these inconsistencies suggest anomalous data not representative of actual site conditions, and the fact

that the potential for exposure to this groundwater is limited, the elevated His related to the Former

Landfill groundwater are not considered significant




All of the estimated carcinogenic risks for both areas are either less than or within the EPA acceptable

risk range of 1 x 10"* to 1 x 10"*. The estimated risk is associated with pretreated water prior to


distribution and is not reflective of current exposure conditions because the pretreated water is not used



2-12          Harding Lawson Associates                                         33537 07.04.oo
                                                                               0308091796 ROD

-------
                                                                           Decision Summary
for domestic purposes. Following treatment by air stripping, the water supply taken from any of the

Schofield Barracks water-supply wells meets MCLs, the federal water quality standards for public

distribution water.




In addition to the quantitative HRA, a qualitative ERA was also developed. Because groundwater from

two wells southwest of Schofield Barracks is used to supplement irrigation water for commercial

pineapple fields, the potential for adverse effects to pineapple plants exposed to TCE in irrigation water

was evaluated. However, adverse effects to pineapple or other plants resulting from low concentrations

of TCE in irrigation water are not expected for several reasons: (1) TCE has a low adsorption capacity

coefficient indicating ready transport through the soil profile, (2) TCE rapidly evaporates from water

and soil to the atmosphere, (3) dilution with other sources of irrigation water will further reduce the

TCE concentrations, and (4) crop impairment from exposure to TCE in growth media has not been

reported in literature.   ..,     .




Actual or threatened releases of hazardous substances from this site, if not addressed by implementing

the response action selected by this ROD, may present an imminent and substantial endangerment to

public health, welfare, and the environment



2.10          Description off Alternatives

Because of the unique and complex hydrogeological conditions at Schofield Barracks and because a

source, or sources, of TCE detected in the Schofield Barracks water-supply wells could not be

identified, it became apparent early in the OU 2 RI/FS program that characterizing the groundwater

system to the extent necessary to evaluate remedial alternatives for a full range of general response

actions would be extremely expensive. Therefore, preliminary FS evaluations were initiated during

Phase I of the RI to allow focusing of Phase n RI evaluations and subsequent FS evaluations.

Development of general response actions that would satisfy remedial action objectives for the site was

undertaken during the Phase I RI. The following general response actions that would satisfy remedial

action objectives were identified:
3353707.04.00                                        Harding Lawsen Associates           2-13
0308120396 ROD

-------
Decision Summary
•      Restoration of the contaminated groundwater system by pumping, treating, and reinjecting the
       groundwater

•      Containment of the contaminated groundwater plume by boundary pumping, treating, and
       reinjecting

•      Treatment of contaminated groundwater at the wellhead when it is extracted from the
       groundwater. system for domestic use. The water within the aquifer will be restored over time
       through natural attenuation.


Because of the complex hydrogeology, depth to groundwater, and aquifer characteristics, restoration of

the groundwater through a pump and treat remedy was not considered practicable. Therefore, only two

general response actions were considered under the OU 2 Feasibility Study:


1.     Containment of the contaminated groundwater plume by a boundary pump and treat system,
       and

2.     Reduction of risk via:

       •      Continued treatment for COCs present in extracted groundwater at the Schofield
              Barracks Supply Wells by air stripping at the wellhead followed by discharge of the
              treated water to the distribution system

       •      The Army must consult with EPA and the DOH prior to abandoning the Schofield
              Barracks water supply wells, because production at these wells may help to control
              plume migration

       •      Long-term sampling and analysis of water supply wells, agricultural wells, and
              monitoring wells in the region

       •      Implementation of the contingency of wellhead treatment on any water supply wells
              that are impacted by the plume from Schofield above one-half the MCL as established
              under the SDWA

       •      Upgrading the treatment system or paying any increment costs caused by
              contamination from Schofield at wells that already have a treatment system in place

       •      Conducting five-year site reviews with the State of Hawaii and the U.S. EPA.


A preliminary evaluation was performed for representative alternatives for each of these general

response actions.  The results of this evaluation (Appendix A of the OU 2 Feasibility study (HLA,

1996a] indicated that the pump and treat remedy, even for containment, was impracticable and as such,

it was not carried through the detailed analysis comparison. The evaluation concluded that the

wellhead treatment option would be protective of human health and the environment.  Because  this
2-14          Harding Lawson Associates                                         3353707.04.00
                                                                               0308120396 ROD

-------
                                                                           Decision Summary
remedy does not restore groundwater within the aquifer, a TI waiver must be invoked, as described in


the Justification for Technical Impracticability Waiver at Schofield Barracks for the Ground Water Record


of Decision, which is part of the Administrative Record for Schofield Barracks.





The feasibility study for OU 2 initially evaluated and developed five alternatives for the wellhead


treatment systems in accordance with CERCLA, the NCP, and relevant EPA and state guidelines,


policies, and procedures. Alternative 1 (no actin) is developed as an NCP requirement and


Alternatives 2 through 5 were developed for wellhead treatment of the extracted contaminated OU 2


groundwater, if necessary.





The feasibility study for OU 2 initially evaluated and developed five alternatives in accordance with


CERCLA, the NCP, and relevant EPA and state guidelines, policies, and procedures. The alternatives


have been developed as a contingency. Alternative 1 (no action) is developed as an NCP requirement


and Alternatives 2 through 5 were developed for wellhead treatment of the extracted contaminated


OU 2 groundwater, if necessary.  Through the screening of alternatives phase of the FS process,


Alternatives 3 (carbon adsorption treatment) and 5 (ultraviolet hydrogen peroxide oxidation treatment)


were considered similar in effectiveness and implementability to Alternatives 2 and 4, but had higher


costs and were eliminated from further evaluation. The remaining three alternatives evaluated in the


OU 2 FS are summarized below. All three remaining alternatives contain the following institutional


controls: groundwater monitoring, and five-year site review. Hawaii DOH requires any new wells


installed as water-supply wells under SDWA to be sampled for the analytes SDWA-specified, which


include TCE and carbon tetrachloride. Additionally, any new wells that are installed within the area


covered by the long-term monitoring network will be added to the existing long-term monitoring


network presented in Figure 2.4. Should these new wells be or become contaminated with COCs that


can be directly attributed to Schofield Barracks, the selected wellhead treatment alternative would be


implemented to address this contamination. The purpose of the groundwater monitoring program will


be to assess groundwater conditions and to track the movement of the TCE- and carbon tetrachloride-


contaminated groundwater plumes to provide an early warning of potential contamination. Five-year



3353707.04.00                                       Harding Lawson Associates           2-15
0308120396 ROD

-------
Decision Summary
site reviews will be conducted to ensure that human health and the environment are protected. The

site review will use the groundwater monitoring program data to assess whether additional action is

warranted.



The location-, chemical-, and action-specific applicable or relevant and appropriate requirements

(ARARs] considered for these three remaining alternatives are summarized in Tables 2.2 through 2.4.


2.10.1        Alternative 1 • No Action/Institutional Controls

Alternative I includes the following components:


•      No action

•      Institutional controls

              Long-term groundwater monitoring

              Five-year site reviews


Under Alternative 1 no further action would take place to reduce/control chemicals in OU 2

groundwater.  Natural fate processes, including degradation and attenuation, would continue to reduce

contaminant concentrations with time in OU 2 groundwater.  The No Action alternative is required as

part of the NCP to provide a baseline against which to compare the other alternatives.


2.10.2        Alternative 2 • Air Stripping

Alternative 2 includes the following components:


•      Treatment of COCs present in groundwater at only those points where it is extracted for
       domestic use by air stripping at the wellhead prior to discharge to distribution system

•      Institutional controls

              Long-term groundwater monitoring

              Five-year site reviews


The treatment component is described below and the institutional control components are described in

Section 2.10.1.
2-16          Harding Lawson Associates                                       33537 07.04.oo
                                                                              0308120396 ROD

-------
                                                                           Decision Summary
 Air-stripping Treatment and Discharge to Distribution System


 Air stripping will be used to reduce the TCE and carbon tetrachloride concentration in groundwater to


 levels below the PRGs, which are the SDWA MCLs. A process flow diagram for the air-stripping


 process is presented in Figure 2.5. The first component of the air stripping system is a bag filtration


 unit for the removal of suspended solids from the extracted groundwater. The air-stripping unit then


 removes TCE and carbon tetrachloride from the filtered groundwater. Treated water from the air-


 stripping unit is routed to a distribution system for domestic use.




 For cost estimating, treatment system conceptual design, and comparative analysis purposes,


 Alternative 2 assumes the treatment of groundwater from three current or future impacted groundwater


 production wells that are used for domestic water-supply purposes that could be impacted by


 contaminated groundwater from Schofield Barracks. The process will include one bag filter unit per


 well, one air-stripper unit per well, and a common collection and distribution system for all three wells

 and treatment units. The installed system will consist of three treatment units, each rated at


 1,500 gallons per minute (gpm), which will be connected to the existing three production wells.


 Operational cost estimates are based on the assumption that the system will operate such that only two


 wells and two treatment units are extracting and  treating groundwater at any given time.  Thus, one

 well and one treatment unit are on standby or in maintenance. This configuration provides for

 continuous treatment of 3,000 gpm of groundwater.




 The three air-stripping units will be constructed on a common concrete pad. The treatment facility will


 be fenced to prevent public entry and potential exposure to untreated groundwater. The treatment


 units will be incorporated into the existing production well/distribution system pipeline to provide for

 discharge into the distribution system.




 Suspended solids removed by the bag filtration units will be disposed hi a nonhazardous landfill.  The


State of Hawaii allows 0.1 ton per year (T/yr) of each hazardous constituent to be emitted uncontrolled
33537 07.04.oo                                       Harding Lawson Associates           2-17
0308120396 ROD

-------
Decision Summary
into the atmosphere (Hawaii Administrative Rules [HARJ, Title 11, Chapter 60.1).  Based on the

mayi'miim influent concentrations of TCE (25 /ig/1) and carbon tetrachloride (8.2 /jg/1) anticipated in

groundwater (see Table 2.5) that could potentially impact water-supply wells to the south of Schofield

Barracks and the projected flow rate of 1,500 gpm per well per air stripper, the air-stripper vapor

discharge will be below .1 T/yr (Table 2.7) and will not require treatment.


2.10.3       Alternative 4 • Ozone/Hydrogen Peroxide Treatment

Alternative 4 includes the following components:


•      Treatment of COCs present in extracted groundwater with ozone/hydrogen peroxide oxidation
       and discharge to the distribution system

•      Institutional controls

              Long-term groundwater monitoring

              Five-year site reviews


The treatment component is described below and the institutional control components are described in

Section 2.10.


Ozone/Hydrogen Peroxide Oxidation Treatment and Discharge to Distribution System

Ozone/hydrogen peroxide will be used to reduce the TCE and carbon tetrachloride concentrations in

the groundwater to levels below the PRGs, which are the SWDA MCLs. A process flow diagram for the

ozone/hydrogen peroxide oxidation process is presented in Figure 2.6.  The first component of the

ozone/hydrogen peroxide oxidation treatment system is a bag filtration unit for the removal of

suspended solids from the extracted groundwater. The ozone/hydrogen peroxide oxidation unit then

removes TCE and carbon tetrachloride from the filtered groundwater. Treated water from the

ozone/hydrogen peroxide oxidation unit is routed to a distribution system for domestic use.



For cost estimating, treatment system conceptual design,  and comparative analysis purposes,

Alternative 4 assumes the treatment of groundwater from three current or future groundwater

production wells that are used for domestic water-supply purposes that could be impacted by
2-18          Harding Lawson Associates                                       33537 07.04.00
                                                                             0306120396 ROD

-------
                                                                           Decision Summary
contaminated groundwater from Schofield Barracks. The process will include one bag filter unit per

well, one ozone/hydrogen peroxide oxidation unit per well, and a common collection and distribution

system for all three wells and treatment units. The installed system will consist of three treatment

units, each rated at 1,500 gpm, which will be connected to the existing three production wells.

Operational cost estimates are based on the assumption that the system will operate such that only two

wells and two treatment units are extracting and treating groundwater at any given time.  Thus, one

well and one treatment unit are on standby or in maintenance. This configuration provides for

continuous treatment of 3,000 gpm of groundwater.




The three ozone/hydrogen peroxide oxidation units will be constructed on a common concrete pad.

The treatment facility will be fenced to prevent public entry and potential exposure to untreated

groundwater. The treatment units will be incorporated into the existing production well/distribution
                                                               /
system pipeline to provide for discharge into the distribution system.




Suspended solids removed by the bag filtration units will be disposed of in a nonhazardous landfill.

Offgas  generated by the ozone/hydrogen peroxide oxidation units will be treated with a catalytic

oxidizer to destroy excess ozone prior to release to the atmosphere.



2.11          Summary off Comparative Analysis of Alternatives

This section provides a comparison of the alternatives described in Section 2.10 with respect to the

following nine NCP criteria: (1) overall protection of human health and the environment; (2) com-

pliance with ARARs; (3) long-term effectiveness and permanence; (4) reduction in toxicity, mobility,

and volume; (5) short-term effectiveness; (6) inaplementability; (7) cost; (8) state acceptance; and

(9) community acceptance. As previously discussed, each of the alternatives incorporates

commonalties including groundwater monitoring and five-year site reviews. Accordingly, these

components of the alternatives were not evaluated in the comparative analysis. Table 2.6 provides a

summary of the comparative analysis of alternatives.
33537 07.04.oo                                        Harding Lawson Associates          2-19
0306120396 ROD

-------
Decision Summary
2.11.1        Overall Protection of Human Health and the Environment

Alternative 1 does not provide any additional protection of human health and the environment.

Alternatives 2 and 4 consist of groundwater treatment at the wellhead prior to distribution for domestic

use.  Alternatives 2 and 4 both offer an increase in protection of human health and the environment.

Alternatives 2 and 4 remove COCs from the groundwater and provide approximately equal protection of

human health and the environment


2.11A        Compliance with ARARs

Alternative 1, no action, does not achieve chemical-specific ARARs. There are no location-specific or

action-specific ARARs for this alternative.



Alternatives 2 and 4 will meet the action-specific ARARs listed in Table 2.4. Neither Alternative 2 nor

4 involves generation of fugitive dust emissions except during construction for which appropriate

preventative measures will be taken and neither alternative will exceed the State of Hawaii air

discharge standards for emissions of volatile organic compounds (VOCs) from point sources.



Both Alternatives 2 and 4 will meet the MCLs required to discharge the treated groundwater into the

water distribution systems.  The proposed wellhead treatment systems will be co-located with existing

and future supply wells and will meet the potential location-specific ARARs listed in Table 2.2.



None of the wellhead treatment options meets the chemical-specific ARARs for restoration of the

groundwater to MCLs. As discussed in Section 2.10, the RI Report, and the FS Report, the unique and

complex hydrogeologic conditions at Schofield Barracks (i.e., 550 to 650 feet thick vadose zone and

highly transmissive fractured basaltic bedrock aquifer) required a unique approach to address

groundwater contamination. A TI waiver to the MCL is therefore justified based on the following

discussion. More detailed discussions are contained in the RI Report (HLA, 1996b), the OU 2 FS Report

(HLA, 1996a), the Justification for Technical Impracticability Waiver at Schofield Barracks for the Ground

Water Record of Decision, and the minutes of the February 24,1994 In-progress Review (IRP).
2-20          Harding Lawson Associates                                        33537 07.04.00
                                                                              0308120396 ROD

-------
                                                                          Decision Summary
2.11.2.1      High Groundwater Volume


The high transmissivity of the Schofield High Level Water Body and the associated high volume of


water flowing through the system would require tremendous extraction and treatment capacities to


address a plume of any substantial size. The Schofield supply wells, pumping at 4 to 5 million gallons


per day, have done nothing to reduce the concentrations of TCE in the aquifer since the stripping


towers were installed in 1986. The average concentration of TCE in the supply wells has remained


steady at approximately 25 to 30 jig/1 over that time period.  Modeling estimates presented at the


February 24,1994, JPR projected extraction/reinjection rates of from 17 million to 56 million gallons per


day would be required to restore the aquifer over a period of 15 to 30 years (depending on the plume


size and location).  An extraction/reinjection rate of approximately 216 million gallons per day was


estimated to be required to restore the groundwater based on application of the OU 2 RI groundwater


model using current information on the plume boundaries.  In addition to the technical difficulties


associated with installing and operating such a vast network of extraction/injection well systems in a


complex bedrock aquifer such as the Schofield High Level Water Body, the power required to run such


a network is not currently available within the Oahu power grid. A new power plant with associated


engineering and operating difficulties would be required to implement such a remedy.



2.11.2.2     Potential Impacts to Basal Aquifers


In addition, the sustainable yield of the Schofield High-Level Water Body has been estimated by the


Honolulu Board of Water Supply at 104 million gallons per day.  Of this, approximately 76 Trillion


gallons per day is required as recharge to the Honolulu-Pearl Harbor Basal Aquifer to avoid salt water


intrusion. Currently 10.7 million gallons per day are pumped by Schofield plateau wells, leaving


approximately 17.7 million gallons per day of increased usage. This would limit the extraction capacity


of a groundwater treatment system network and would make the groundwater resource unavailable for


productive use or would require installation of a reinjection well network As discussed above, the


projected extraction rate required to restore the Schofield High Level Water Body is estimated at


approximately 40 million gallons per day which would exceed the extraction limits and would thus


require reinjection.



33537 07.04.00                                       Harding Lawson Associates           2-21
0308120396 ROD

-------
Decision Summary
2.11.2.3     Protectiveness of Wellhead Treatment

The limitation on groundwater extraction likewise puts an upper bound on the future number of

production wells potentially requiring treatment, which, in turn, further supports the Army's selection

of wellhead treatment of impacted wells rather than active pump and treat of the aquifer. Wellhead

treatment will provide adequate protection of human health and the environment in a cost-effective

manner and will meet the intent of the Safe Drinking Water Act MCLs by ensuring that the water-

supply systems are providing safe drinking water to Oahu residents.


2.11.3       Long-term Effectiveness and  Permanence

Alternative 1 does not provide any additional risk reduction over the long term. Alternatives 2 and 4

provide an increase in long-term effectiveness and permanence by treating extracted OU 2 groundwater

prior to distribution for domestic use. The treatment technology to be employed by both Alternatives 2

and 4 are proven  technologies with a long track record of effectiveness and reliability. Monitoring of

the groundwater supplies as required under the Safe Drinking Water Act, further ensures that TCE and

carbon tetrachloride levels in the treated water supply will be maintained below the MCL.  The

technology employed in Alternative 4 breaks down TCE and carbon tetrachloride into nonhazardous

products eliminating concerns about residual contamination.  Although Alternative 2 simply removes

the TCE and carbon tetrachloride from the water through volatilization, modeling projections indicate

that the emissions from the air stripping towers will be low and are well below EPA's acceptable risk

ranges (see discussion in Section 2.13, Protection of Human Health and the Environment).


2.11A        Reduction In ToxicKy, Mobility, and Volume

Alternative 1 does not provide a reduction in toxicity, mobility, or volume except through natural

attenuation of COCs in the OU 2 groundwater system.  Alternative 4 provides  an increased reduction in

toxicity, mobility, and volume by destroying the COCs in the ozone/hydrogen peroxide oxidation unit.

Alternative 2 also provides an increased reduction in toxicity, mobility, and volume of COCs although

the COCs are transferred to the atmosphere as VOCs rather than destroyed.
2-22          Harding Lawson Associates                                       33537 07.04.00
                                                                             0308120396 ROD

-------
                                                                         Decision Summary
 2.11.5        Short-term Effectiveness


 The short-term conditions at the site would remain unchanged under Alternative 1 because no action is

 implemented. Alternatives 2 and 4 will have minimal short-term impacts to the community and

 workers associated with construction of a concrete slab and installation of the treatment system

 equipment. Alternatives 2 and 4 will likely create some minimal short-term ecological and environ-

 mental effects due to construction activities from dust generation, vegetation clearing, and general

 construction noise.



 2.11.6        Implementability


 The only technical aspect of Alternative 1 is the implementation of the groundwater monitoring

 program to re-evaluate the site in five years. Groundwater monitoring is also a component of

 Alternatives 2 and 4 to support decisions on implementing remedial action at impacted wells.  The

 Army, Hawaii Department of Health and EPA. as well as the Honolulu Board of Water Supply and the

 public, will be involved in the review of monitoring data to analyze trends and to determine when

 wellhead treatment is required.




 Alternatives 2 and 4 are considered to be technically implementable. Both treatment systems involve

 components that are readily available from several vendors.



 2.11.7        Cost


 The net present worth of Alternative 1, Alternative 2, and Alternative 4 are $1,350,000, $3,900,000, and

 $5,910,000, respectively. A breakdown of capital cost, operation and maintenance (O&M) cost, and net

 present worth for each alternative is presented in Table 2.8.



 2.11.8        State Acceptance


As indicated by DOH approval of the Final OU 2 FS and Proposed Plan, Alternative 2 is more

acceptable to the State than Alternatives 1, 3,4, and 5.
33537 07.04.oo                                      Harding Lawson Associates          2-23
0308120396 ROD

-------
Decision Summary
2.11.9        Community Acceptance

Community acceptance is documented in Section 3.0 (Responsiveness Summary).


2.12          Selected Remedy

Based on consideration of the requirements of CERCLA, the detailed analysis of alternatives, and public

comment, the Army, EPA, and DOH have determined that a remedy with the following components is

the preferred remedy for Schofield Barracks OU 2:


•      Continued treatment for COCs present in extracted groundwater at the Schofield Barracks
       Supply Wells by air stripping at the wellhead followed by discharge of the treated water to the
       distribution system

•      The Army must consult with EPA and DOH prior to abandoning the Schofield Barracks water
       supply wells, because production at these wells may help to control plume migration

•      Long-term sampling and analysis of water supply wells, agricultural wells and monitoring wells
       in the region

•      Implementation of the contingency of wellhead treatment on any water supply wells that are
       impacted by the plume from Schofield Barracks above one-half the MCL as established under
       the SDWA

•      Upgrade the treatment system or pay any incremental costs caused by contamination from
       Schofield Barracks at wells that already have a treatment system in place

•      Conduct five-year site reviews with the State of Hawaii and the U.S. EPA.


The details of the monitoring plan, evaluation process for implementation of wellhead treatment, and

description of conditions at existing water wells may be found in the Final Operation and Maintenance

and Long-Term Groundwater Monitoring Plan for Operable Unit 2, Schofield Army Barracks, which is an

addendum to this ROD.
Alternative 2 (air stripping) is the preferred alternative for the wellhead treatment systems. The

comparative analysis indicates that Alternative 2 is preferred to Alternative 4 (ozone/hydrogen

peroxide/oxidation) with respect to cost However, Alternative 2 is considered equal to Alternative 4

with respect to protection of human health and the environment, compliance with ARARs, long-term

effectiveness and permanence, short-term effectiveness, and implementability.
2-24         Harding Lawson Associates                                        33537 07.04.oo
                                                                              0308120496 ROD

-------
                                                                          Decision Summary
 The major costs associated with Alternative 2 are presented in Table 2.9.



 For comparative analysis purposes a treatment system conceptual design was assumed for treatment of

 groundwater from three current or future impacted groundwater production wells that are used for

 domestic water-supply purposes that could be impacted by contaminated groundwater from Schofield

 Barracks. The conceptual air stripper treatment system design consists of three treatment units, each

 rated at 1,500 gpm, connected to three existing domestic water-supply production wells. However,

 there are potentially seven existing water production well systems with a varying number of production

 wells at varying flow rates that could be impacted by Schofield Barracks groundwater. Three of the

 seven existing production well systems are currently treating the extracted groundwater to remove

 pesticides using carbon adsorption. If TCE-contaminated water from Schofield Barracks impacts any of

 the existing three water-supply carbon adsorption systems, the carbon usage rates may increase over

 their normal carbon usage rates at these systems. The impact to carbon usage at these three systems

 was modeled to estimate the possible carbon usage increase. The  results of the modeling are

 summarized in Appendix B. The modeling results indicate that the carbon usage rate will likely

 increase as the concentrations of TCE increase. Therefore, the Army will be responsible for sharing

 some carbon usage costs until the air stripper system is installed.


 2.13         Statutory Determinations

 Under its legal authorities, EPA's primary responsibility at Federal Facility NFL sites is to oversee

 remedial actions that achieve adequate protection of human health and the environment. In addition,

 Section 121 of CERCLA establishes several other statutory requirements and preferences. These specify

 that, when complete, the selected remedial action for this site must comply with applicable or relevant

 and appropriate environmental standards established under federal and state environmental laws unless

 a statutory waiver is justified. The selected remedy also must be cost effective and utilize permanent

solutions and alternative treatment technologies or resource recovery technologies to the maximum

extent practicable. Finally, the statute includes a preference for remedies that employ treatment which
33537 07.04.00                                       Harding Lawson Associates           2-25
0308120396 ROD

-------
 Decision Summary
 permanently and significantly reduces the volume, toxitity, or mobility of hazardous wastes as their


 principal element. The following sections discuss how the selected remedy meets these statutory


 requirements.



 Protection of Human Health and the Environment


 Overall protection of human health and the environment will be provided by the selected remedy prior


 to distribution of the OU 2 groundwater. Based on the baseline risk assessment (HLA, 1996a), no


 current populations with exposure to contaminated OU 2 groundwater were identified onsite or offsite.


 Additionally, groundwater modeling was performed to evaluate contaminant migration both with and
                *                        -...

 without the impacts of retardation and degradation. The modeling results using no degradation and


 retardation indicate that the OU 2 plume may migrate offsite to the south, flowing across the southern


 groundwater dam at concentrations above 5 tig/I within 5 years but will not likely impact current


 downgradient water-supply wells for approximately 100 years. Modeling results using high retardation


 and degradation indicate no impact to downgradient water-supply wells. Alternative 2 was developed


 to address the contaminated OU 2 plume if it does migrate offsite, the COC concentrations exceed the


 MCLs, and the OU 2 groundwater is extracted in new or existing potable water-supply wells. Contami-


 nated OU 2 groundwater will be treated by an air stripper at the wellhead to remove COCs to concen-


 trations below the MCLs prior to distribution for domestic use. Because air stripping does not destroy


 TCE or carbon tetrachloride prior to vapor discharge to the atmosphere, an air dispersion model and a


 theoretical risk assessment were performed to evaluate potential health risks posed by the air stripper


 vapor discharge.  To perform a theoretical risk assessment for the constituents, the EPA single-source


 dispersion model SCREENS (EPA, 1995) was first used to calculate airborne concentrations of TCE and


 carbon tetrachloride within 3,281 feet (1,000 meters) of the air strippers.  Using model results and EPA


 guidance, the highest annual average air concentration for TCE was predicted to be 0.079 micrograzns


 per cubic meter (fig/m3).  The equivalent concentration for carbon tetrachloride was predicted to be


 0.026 ng/m3. The model results indicated that the mayinnjm concentration would occur at a distance of


 2,162 feet (659 meters) from the air strippers.
2-26          Harding Lawson Associates                                         33537 07.04.oo
                                                                               0308120396 ROD

-------
                                                                          Decision Summary
Using the SCREENS model results, a theoretical risk assessment was performed for the air stripper

airborne concentrations of TCE and carbon tetrachloride.  The cumulative risks associated with the

predicted concentrations of the constituents are well below EPA's acceptable cancer risk range of 10~* to

10*6.  In addition, the noncancer hazard indices are well below EPA's acceptable level of 1.0.  The

calculated cumulative cancer risk for the two constituents was 2.2 x 10"7 and the calculated cumulative

hazard index was 0.012. Based on the dispersion model and risk assessment results, no significant

health risks are expected for the constituents calculated to be released from the conceptual design air

strippers. Additionally, institutional controls as discussed in Section 2.10 will be implemented to

reduce the chance of inadvertent exposure.



Natural attenuation will be the primary mechanism for contaminant concentration reduction in the

aquifer (Schofield High-level Water Body) eventually eliminating the need for treatment. Periodic

groundwater monitoring and five-year site reviews will provide data to indicate when contaminant

levels in groundwater have attained MCLs.


Compliance with ARARs

The location-, chemical-, and action-specific ARARs are listed below:


•      Location-specific ARARs:

              16 United States Code  (USC) 661 et seq., 662 and 663, requiring actions to be taken to
              prevent, mitigate, or compensate for project-related damages or losses to fish and
              wildlife resources.

               Clean Water Act (CWA) 404, 33 CFR 320-330, and 40 Code of Federal Regulations
              (CFR) 230, prohibiting discharges that cause or contribute to significant degradation of
              the water of ecosystems.

              HC 183D-61 et seq., prohibiting interference with wild birds or their nests.

              CWA 404, prohibiting the discharge of fill material into aquatic ecosystems that would
              jeopardize endangered, threatened, or rare species.

              HC 194D-4,16 USC 1531 et seq., 50 CFR 402 prohibiting actions that jeopardize
              endangered or threatened species or critical habitat of such species as designated in
              50 CFR 17, 50 CFR 226, or 50 CFR 227.
33537 07.04.oo                                       Harding Lawson Associates           2-27
0308120396 ROD

-------
 Decision Summary
 •       Chemical-specificARARs:

               40 CFR, Part 141, (b) and (g), defining SDWA MCLs.

               40 CFR, Part 141, (f), defining SDWA maximum contaminant level goals (MCLGs).

 •       Action-specific ARARs:

               Hawaii Administrative Rule (HAR) 1 l-60.1-33(a)(l)-(7) and (b). prohibiting the dis-
               charge of visible fugitive dust emissions beyond the property lot line on which the dust
               originates and requiring precautions to prevent fugitive dust emissions.

               HAR 11-60.1-68, requiring monitoring of VOC emissions if emissions are greater than
               1 ton per year for each hazardous air pollutant.

               40 CFR, Part 141, (b) and (g), defining MCLs.


While the selected alternative will treat groundwater at the wellhead to concentrations below the MCLs,

a waiver for the chemical-specific ARAR, as applied to the contaminated aquifer, is required based on

the technical impracticability of groundwater restoration to below the MCL concentrations. A detailed

justification for the TI waiver is provided in Section 2.11.2 of this ROD.


Other Criteria, Advisories, or Guidance To Be Considered for Remedial Action

In implementing the selected remedy, EPA and the State of Hawaii have agreed to consider a number of

procedures that are not legally binding (known as to be considered fTBCs]). These include the

following:


•      40 CFR 6.302(g) and (h), requiring actions to be taken to prevent, mitigate, or habitat
       compensate for project-related damages or losses to fish, wildlife resources, or critical habitat.

•      EPA Office of Water Lifetime Health Advisories for 70-kg Adult, May 1995, defining tnayim^im
       recommended concentration of a given chemical in drinking water.

              EPA Office of Water Health Advisory, May 1995, defining the concentration of a given
              chemical in drinking water that will result in one excess cancer death in one million
              people.

              40 CFR 300.430(a)(l)(iii)(D), requiring institutional controls to prevent or limit exposure
              to hazardous substances, pollutants, or contaminants.


Cost Effectiveness

The selected remedy is cost effective, providing overall effectiveness proportional to its costs.  The net

present worth of the selected remedy is $3,990,000. While Alternative 1 offers the lowest estimated


2-28          Harding Lawson Associates                                         33537 07.04.00
                                                                               0308120396 ROD

-------
                                                                        Decision Summary
 cost, it does not provide long-term effectiveness.  Considering Alternatives 2 and 4 provides comparable

 long-term effectiveness, but the estimated cost of Alternative 2 is less than Alternative 4, Alternative 2

 provides the best combination of cost and long-term effectiveness.



 Utilization of Permanent Solutions and Alternative Technologies to the Maximum Extent
 Practicable

 The U.S. Army, in coordination with EPA and the State of Hawaii, determined that the selected remedy

 represents the maximum extent to which permanent solutions and treatment technologies can be used

 in a cost-effective manner for OU 2.  The selected remedy provides the best balance of tradeoffs in

 terms of long-term effectiveness and permanence; reduction in toxicity, mobility, or volume; short-term

 effectiveness; implementability; and cost.




 Although Alternative 4 is comparatively effective in the long term, Alternative 4 has a greater estimated

 cost. The selected remedy addresses the principal threat posed by the contaminated OU 2 groundwater

 efficiently and cost effectively.



 Preference for Treatment as a Principal Element

 The statutory preference for remedies that employ treatment as a principal element is  satisfied by the

 selected remedy. The principal threat of the site is the potential for domestic use of contaminated

 groundwater with COC concentrations above PRGs. The selected remedy adequately addresses this

 threat by treating the OU 2 groundwater at the wellhead to remove COCs to concentrations below the

 PRGs prior to distribution for domestic use.
33537 07.04.oo                                      Harding Lawson Associates           2*29
0308120396 ROD

-------
      Table 2.1: Summary off Noncarcinogenic and Carcinogenic Risks for OU 2
Hazard Index
Receptor/Pathway
East Range Area - Adult
Groundwater Ingestion
Groundwater VOC Inhalation
Groundwater Dermal
Total
Maximum TCE* - Adult
Groundwater Ingestion •
Groundwater VOC Inhalation
Groundwater Dermal
Total
Former Landfill - Adult
Groundwater Ingestion
Groundwater VOC Inhalation
Groundwater Dermal
Total
East Range Area - Child
Groundwater Ingestion
Groundwater VOC Inhalation
Groundwater Dermal
Total
Maximum TCE* - Child
Groundwater Ingestion
Groundwater VOC Inhalation
Groundwater Dermal
Total
Former Landfill - Child
Groundwater Ingestion
Groundwater VOC Inhalation
Groundwater Dermal
Total
Average
6.39E-02
1.32E-02
9.91E-03
8.70E-02

1.56E-01
NA
7.43E-02
2.30E-01

4.31E-01
7.45E-02
1.04E-02
5.16E-01
1.70E-01
3.52E-02
2.61E-02
2.32E-01

4.16E-01
NA
1.96E-01
6.11E-01

1.15E+00
1.99E-01
2.75E-02
1.38E+00
RME
3.96E-01
3.12E-02
2.23E-02
4.50E-01

6.23E-01
NA
1.04E-01
7.27E-01

2.75E+00
2.84E-01
2.91E-02
3.07E+00
1.20E+00
9.48E-01
5.88E-02
1.35E+00

1.89E+00
NA
2.74E-01
2.16E+00

8.35E4-00
8.62E-01
7.68E-O2
9.29E+00
Carcinogenic Risk
Average RME
2.33E-07
2.37E-07
8.42E-08
5.55E-07

1.32E-06
1.44E-06
6.31E-07
3.40E-06

5.02E-07
4.50E-07
8.63E-08
1.04E-06
2.08E-07
2.11E-07
7.40E-08
4.92E-07

1.18E-06
1.28E-06
5.54E-07
3.01E-06

4.46E-07
4.00E-07
7.58E-08
9.22E-07
4.67E-06
2.41E-06
6.31E-07
7.72E-06

1.76E-05
9.62E-06
2.94E-06
3.02E-05

1.30E-05
5.87E-06
8.15E-07
1.97E-05
2.84E-06
1.46E-06
3.32E-07
4.63E-06

1.07E-05
5.83E-06
1.55E-06
1.81E-05

7.91E-06
3.56E-06
4.30E-07
1.19E-05
NA     Not applicable
OU     Operable unit
RME    Reasonable maximum exposure
TCE     Trichloroethene
VOC    Volatile organic compound
*  Based on maximum depth-specific sampling result from the Schofield Barracks water-supply wells.
33537 07.04.00
0902082996 ROD
Harding Lawson Associates

-------
                                                   Table 2.2i Location-specific Applicable or Relevant and
                                                   Appropriate Requirements for Sehofteld Barracks OU 2
          Location Characteristic!*)
         Prflr«qulflle(s)
                Raquiremenl(s)
           Cltation(s)
   WilderneM areas, wildlife resources,
   wildlife refuges, or scenic rivers

   •  Within (iron affecting stream or river •
      and - presence of fish or wildlife
      resources
      Location encompassing aqunllc
      ecosystem with dependent fish,
      wildlife, other aquatic life, or hnbitnt
      Presence of wild birds or their nests
Presence of fish or wildlife resources;
nctlon by federal ngency Ihnl results
in the control or structural
modification of a natural stream or
body of water

Offslte response action
Actlon(s) Involving the discharge of
dredge or fill material Into aquatic
ecosystem
The effects of water-related projects on fish and
wildlife resources must be considered.

Action must be taken to prevent, mitigate, or
compensate for project-related damages or losses to
fish and wildlife resources.

Offslto actions that alter a resource require
consultation with the FWS. NMFS, and/or the
appropriate state agency.

Consultation with the responsible agency Is also
strongly recommended for onslte actions.

Degradation or destruction of aquatic ecosystems must
be avoided to the extent possible.  Discharges that
cnuse or contribute to significant degradation of the
water of such ecosystems are prohibited.
                                       The Intentional, knowing, or reckless taking, catching,
                                       Injuring, killing, destroying, or keeping In captivity or
                                       possession of wild birds Is prohibited.

                                       Damaging or destroying the nests of wild birds Is
                                       prohibited.
Fish and Wildlife Coordination Act
(16 USC 661 ef sen.). §§662 and 663 •
'applicable

40 CFR §6.302(g) (applies to federal
agencies only) • TBC
Clean Water Act §404 - applicable

40 CFR §230 • applicable

33 CFR §320-330 • applicable

HC §1830-61 ef sea. • applicable
   Endangered, threatened, or rare species

   •   Presence of endangered or threatened
      species or critical habitat (see above
      citation)  of same within an aquatic
      ecosystem as defined In 40 CFR
      §230.3(c)

   •   Presence of federal or stale
      endangered or threatened species

   •   Presence of endangered or threatened
33537 07.0« ""
01120830'
Action Involving discharge of dredge
or fill material into aquatic ecosystem
Action that Is likely to jeopardize
Dredge or fill material shall not be discharged Into an
aquatic ecosystem If It would Jeopardize such species
or would likely result In the destruction or adverse
modification of a critical habitat of the species.
The taking of any threatened or endangered species
within the state Is prohibited.

Actions that jeopardize species/habitat must be
Clean Water Act §404 • applicable

40 CFR §230.10(b) • applicable



HC §1950-4 • applicable


Endangered Species Act of 19Z3M6
I^fl
                                                                                                                             of 2

-------
                                                                          Table 2.2 (continued)
          LocnUon Cnaraclorlstlc(i)                     Prerequlilte(s)                                  Requirement)*)                                    Clt>Uon(s)


      apocloi -or- crltluil hnlilini of inch         species or destroy or adversely             nvoldod or «|>|>ro|irlitle mlllgnllon moRsuros Inkon.          USC 1531 or tea,.) • applicable
      species ns doilgnnloil In SO CFK §17.       modify critical habitat
      50 CFK §220. or 50 CFH §227                                                   •   Offsllo actions thai affect spoeloa/habllM require         •   SO CFR §402 • applicable
                                                                                      conciliation with DO). FWS, NMFS. and/or ilale
                                                                                      agonclei. at approprlato. to ensure thai proposed         •   40 CFR $6.302(h) • TBC
                                                                                      actloni do not jeopardize the continued existence of
                                                                                      the tpeclea or adversely modify or destroy critical        •   Fish and Wlldllfo Coordination Act
                                                                                      habitat.                                                (16 USC 661 tt «*j.) • applicable

                                                                                   •   Consultation with the responsible agency U aj*o
                                                                                      strongly recommended for onslto action*.
Source: Unllod Slnlos Army Environmental Cantor

CFR    Coda of Fodarnl Rogulnlloni
DOI    Do|),,rlmont of Interior
FWS    U.S. Flih nnd Wlhlllfo Service
IIC     IInwnll Citation
NMFS  Notional Marino Fisheries Service
TIIC    To bo conalclorod  .
USC    United States Code
3353707.04.00                                                                                           '                                                                 2 Of 2
01120B309GROD

-------
          Table 2.3: Chemical-specific Applicable or Relevant and Appropriate
                    Requirements and "To-Be-Considered" Guidance for
                   Cleanup of Groundwater at Schofield Barracks OU 2*
Relevant and ADDrooriate Reauirements
Chemical
Acetone
Benzene
bis(2-Etbylhexyl)phthalate
SDWAMCLs'
(mg/I)
5
5
6
Hawaii MCLs'
(ma/1)
5
SDWAMCLGsr
(mg/1)
0
0
TBC Guidance0
Health
Advisories8
(mjs/1)
lh
3h
  2-Butanone (methyl ethyl ketone)
  Carbon disulfide
  Carbon tetrachloride                  5
  Chlorome thane
  1.1-Dichloroethane
  1.2-Dichloroethane                   5
  cis-1.2-Dichloroethene                70
  trans-1.2-Dichloroethene              200
  Ethylbenzene                        700
  2-Hexanone
  4-Methyl-l-pentanone
  4-Methyl-2-pentanone
  Methylene chloride                   5
  Nitrobenzene
  Phenol
  Pyrene
  1.1.2.2-Tetrachloroethane
  Tetrachloroethene                    5
  Toluene                             1.000
  Trichloroethene                      5
  Vinyl chloride                       2
  Xylenes, total                        10.000
5
70
100
700
5
1.000
5
2
10,000
0
0
0
700
0
1,000
0
0
20,000
0.3n



0.4"



700




5h

4,000


0.7"
1,000
3h

10,000
Source:   United States Army Environmental Center

ARARs   Applicable or relevant and appropriate requirements
CERCLA  Comprehensive Environmental Response, Compensation, and Liability Act
CFR     Code of Federal Regulations
EPA     U.S. Environmental Protection Agency
HA      Health advisory
MCL     Maximum contaminant level
MCLG    Maximum contaminant level goal
mg/1     Miligrams per liter
SDWA    Safe Drinking Water Act
TBC     To be considered
USAEC   U.S. Army Environmental Center

a.   This table provides ARARs or TBC guidance for all chemicals detected in the groundwater at Schofield
    Barracks, as reported in Figure 3.5 of the Draft Final Sampling and Analysis Plan for Operable Unit 4 Phase II
    Remedial Investigation and Feasibility Study Field Program. August 19.1994. The bolded and italicized
    values indicate the ARAR or TBC for each chemical. The MCLs/MCLGs in this table are relevant and
    appropriate requirements for cleanup of extracted groundwater. The MCLs would be applicable "at the tap.'
    These decisions are based on the determination that the underground water system at Schofield Army
    Barracks is a public water system designated as a Community Water System by the Hawaii Department of
33537 07.04.00                                         Harding Lawson Associates           1  of 2
0115083096 ROD

-------
                                      Table 2.3 (continued)


     Health. Division of Drinking Water (Personal communication with A. Zane, Engineer. Division of Drinking
     Water, July 25,1995). A Community Water System is "a public water system which serves at least 15
     connections used by year-round residents or regularly .serves at least 25 year-round residents." (40 CFR §
     141.2 Definitions [1994] and Hawaii Administrative Rules 20 § 11-20-2 Definitions [1994]).

b.   Relevant and appropriate requirements are "those cleanup standards, standards of control, and other
     substantive requirements, criteria, or limitations promulgated under federal environmental or state
     environmental or facility siting laws that while not 'applicable' to a hazardous substance, pollutant,
     contaminant, remedial action, location, or other circumstance at a CERCLA site, address problems or
     situations sufficiently similar to those encountered at the CERCLA site that their use is well suited to the
     particular site." (40 CFR § 300.5 Definitions. [1994]). "Maximum contaminant level goals (MCLGs).
     established under the Safe Drinking Water Act. that are set at levels above zero, shall be attained by remedial
     actions for ground waters that are current or potential sources of drinking water, where the MCLGs are
     relevant and appropriate under the circumstances of release.* (40 CFR § 300.430[e][2][i)[6] [1994]).

c.   This "category consists of advisories, criteria, or guidance that were  developed by the EPA. other federal
     agencies, or states that may be useful in developing CERCLA remedies.* (40 CFR § 300.400[g][3] [1994]).
     TBCs are nonpromulgated advisories and are not legally binding. They "do not have the status of potential
     ARARs.* (CERCLA Compliance with Other Laws Manual Draft Guidance. USEPA OSWER Directive 9234.1-
     01.1968.)

d.   40 CFR Part 141 Subpart B and Subpart G (1994).

e.   State of Hawaii Maximum Contamination Levels. Rules Relating to  Potable Water Systems Title 11 Chapter
     20 §§ 11-20-2, -3. and -4. as amended, originally effective August 6,1977. as Chapter 49 of the Public Health
     Regulations, Department of Health.

f.   40 CFR Part 141 Subpart F (1994).

g.   USEPA Office of Water Lifetime Health Advisories (HAs) for a 70-kg Adult, May 1995.

h.   USEPA Office of Water Health Advisory representing a 1 x 10* cancer risk, the concentration in drinking
     water that will result in one excess cancer death in one million people (May 1995).

i.   Under review. Drinking Water Regulations and Health Advisories. USEPA Office of Water, May 1995.
2 of 2         Harding Lawson Associates                                             33537 07.04.00
                                                                                       0830960115 ROD

-------
                              Table 2.4: Action-specific Applicable or Relevant and Appropriate Requirements
                                                   for OU 2 at Schofleld Army Barracks, Hawaii
             Actions
                      Requirements
    Prerequisite*
  Federal Citation
Hawaii Citation
 Alternative 1 No Action

 Institutional controls
Instltnllonnl controls such as writer use and deed restrictions to
supplement engineering controls AS npproprlnte for short- and
long-term management to prevent or limit exposure to
linznrdons substances, pollutants, or contaminants.
Presence of hazardous
substances, pollutants.
or contnmlnnnts.
40 CFR §
300.430(ft)(l)(lll)(D)
to be considered.
 Alternative 2 Air Stripping

 Fugitive dust emissions
Visible fugitive dust emissions must not be discharged beyond
the property lot line on which the fugitive dust originates.

Reasonable precautions must be used to proven! fugitive dust
emissions.
Fugitive emissions
from excavation of
contaminated soil and
construction of pads.
                    §ll-eo.1-33(a)(l)
                    through (7) and (b)
                    applicable
 Air emissions from the air stripper
Administrative and substantive requirements of permit If
exemption listed at §ll-60.1-02(d)(l) cannot be met.
Requirements Include the Installation of devices for the
measurement or analysis of source emissions or ambient
concentrations of air pollutants; monitoring; and requirements
concerning the use, maintenance, and Installation of
monitoring equipment.
Exemption under §11*
60.1-62(d)(l) cannot
be met.            '
                     Sll-60.1-08
                     applicable
 Discharge of treated groundwater
Comply with MCLs. See Section 3 of the OU 2 FS Report fora
discussion of MCLs.
Discharge of treated
groundwaler Into
water distribution
system.
335371
oiisol

-------
                                                               Table 2.4 (continued)
             Actions
Requirements
Prerequisites
Federal Citation      Hawaii Citation
 Alternative 4 Peroxide/Ozone Oxidation

 Fugitive dust emissions            Sea Alternative 2


 Discharge of (rented groniidwnler    See Alternative 2
CFR    Code of Federal Regulations
MCL    Maximum contaminant level
RCRA   Resource Conservation and Recovery Act
UV     Ultraviolet
33S;i707.ni.OO
(111.1003091) KOD
                                                                                            2«I2

-------
   Table 2.5: Preliminary Estimated Influent Chemicals of Concern Concentrations
                 and Proposed Treatment Standards for Schofield Army Barracks OU 2
                                                Estimated Range
                                                of Groundwater
                                                    Influent          Federal
                                                Concentrations       MCLs*
                  Chemicals of Concern                frtg/1)            frg/1)

           Carbon tetrachloride                      <1b to 8.2b           5
           Trichloroethene                          
-------
                                          Table 2.6: Summary of Comparative Analysis of Alternatives
      Evaluation Criteria
             Alternative 1
               No Action
              Alternative 2
   Groundwater Extraction, Air Stripping
               Alternative 4
 Groundwater Extraction, Ozone/Hydrogen
            Peroxide Oxidation
  Effectiveness

  Overall protection of human
  health and the environment
Inadequate; uncertainty regarding time
frame when OU 2 groimdwnter plume
would migrate offsite and what the TCE
concentration would be. Natural
attenuation will be the primary mechanism
for reducing contaminant concentration in
the aquifer.
Protective; Immediately upon treatment and
prior to distribution of the OU 2 groundwater
for domestic use. Natural attenuation will be
the primary mechanism for contaminant
concentration reduction in the aquifer.
Protective; immediately upon treatment and
prior to distribution of the OU 2 groundwater.
Natural attenuation will be the primary
mechanism for contaminant concentration
reduction In the aquifer.
  Compliance with ARARs
  and other guidance
No action does not achieve chemical-
specific ARARs, however, through natural
attenuation chemical-specific ARARs are
expected to be achieved; there are no
action-specific ARARs and no location-
specific ARARs.
Air stripping can meet chemical-specific
ARARs immediately through treatment at the
wellhead, and with time through natural
attenuation. However, because the alternative
will not actively restore the aquifer to below
MCL concentrations, a TI waiver has been
invoked for this ARAR. Action-specific and
location-specific ARARs are expected to be
met by this alternative.
Ozone/hydrogen peroxide oxidation can meet
chemical-specific ARARs immediately
through treatment at the wellhead, and with
time through natural attenuation. However,
because the alternative will not actively
restore the aquifer to below MCL
concentrations, a TI waiver has been invoked
for this ARAR.  Action-specific and location-
specific ARARs are expected to be met by this
alternative.
  Long-term effectiveness
Through deed restriction this alternative
will reduce residual risk associated with
the groundwater within the OU 2 plume
onsite. Future hypothetical risk and
exposure pathways would continue to pose
a threat to human health  and the
environment. Natural attenuation will
eventually contribute to the attainment of
MCLs and the elimination of residual risk
and threat to human health and the
environment.
Treatment at the wellhead combined with
natural attenuation will eventually contribute
to the attainment of MCLs and the
elimination of residual risk and threat to
human health and the environment.
Treatment at the wellhead combined with
natural attenuation will eventually contribute
to the attainment of MCLs and the elimination
of residual risk and threat to human health
and the environment.
33537 07.04.00
0205083006 ROD
                                                                                                                        1 of 3

-------
                                                                Table 2.6  (continued)
      Evaluation Criteria
             Alternative 1
              No Action
              Alternative 2
   Groundwaler Extraction, Air Stripping
              Alternative 4
 Groundwater Extraction, Ozone/Hydrogen
            Peroxide Oxidation
  Reduction of toxicity,
  mobility, and volume
No reduction in mobility, toxicity, or
volume from treatment.  However,
reduction in toxicity, mobility, and volume
through natural attenuation and
degradation.
Extracted groundwater will have a reduction
in toxicity and volume providing protection
to human health and the environment.
However, reduction in mobility, toxicity, and
volume will not occur to a large extent in the
contaminated groundwater system, except
through natural attenuation.
Contaminants In extracted groundwater will
be reduced in toxicity and volume providing
protection to human health and the
environment. However, reduction in
mobility, toxicity, and volume will not occur
in the contaminated groundwater system,
except through natural attenuation.
  Short-term effectiveness
Unchanged; Army controls access to the
site and groundwater removal and use.
Impacts to the community and workers will
be minimal during construction of the
concrete pad and set up of the treatment
equipment. Possible short-term ecological
and environmental effects due to construction
activities from dust generation, vegetation
clearing, and constniction noise.
Impacts to the community and workers will
be minimal during constniction of the
concrete pad and set up of the treatment
equipment. Possible start-term ecological
and environmental effects due to constniction
activities from dust generation, vegetation
clearing, and constniction noise.
  Implementability
Technically feasible to implement
groundwater monitoring program.
Technically feasible to implement.
Conventional equipment used in this
alternative. Effectiveness monitored through
process monitoring and groundwater
monitoring.
Technically feasible to implement.
Conventional equipment used in this
alternative. Effectiveness monitored through
process monitoring and groundwater
monitoring.
  Cost
33537 07.04 "O
02050829
Total Estimated Capital Cost = $0

Total Estimated Annual Operation and
Maintenance Cost = $87,500

Total Estimated Present Worth =
$1,350.000
Operating Flow Rate = 3,000 gpm

Total Estimated Capital Cost = $650,000

Total Estimated Annual Operation and
Maintenance Cost = $217,000
Operating Flow Rate = 3,000 gpm

Total Estimated Capital Cost = $1,500,000

Total Estimated Annual Operation and
Maintenance Cost = $287,000
                                                                      Total Estimated Present Worth = $3,990,000   Total Estimated Present Worth = $5,910,000

                                                                                                                                                    2 of 3

-------
                                                             Table 2.6  (continued)
ARAR  Applicable or relevnnt and appropriate requirement
gpm   Gallons per minute
OU    Operable unit
PRG   Preliminary remediation goal
TCE   Trichloroethene
33537 07.04.00
0205082006 ROD
                                                                                                                                             3 of 3

-------
                 Table 2.7: Calculations for Estimated Maximum Trlchloroethene Vapor Discharge from
                                         Alternative 2 (Air Stripping Treatment)


Assumptions:

•      Maximum influent groundwater flow rate into the air stripper is 1,500 gallons per minute (gpm)

•      The trichloroethene (TCE) concentration of 25 micrograms per liter (ug/1) is based on influent concentration data to the Schofield
       Barracks water supply well air stripper treatment system.


Trichloroethene (TCE)

(    1 gram    ^ (  1 pound  "j ( 3.785liters! f   60minutes  \ f 1.500gallons^ ^.025milligrams"] ( 24 hour^ f 365day'j
U,000milligrams/Us3.8gramsJ I   gallon  J U,000milligrams/v   minute   ) (.      liter     )\  day  )\  year  )

 = 164 pounds per year of TCE.
         ROD

-------
       Table 2.8: Summary of Estimated Costs for Remedial Action Alternatives
                        at Schofield Army Barracks for OU 2

Alternative 1:
Alternative 2:
Alternative 4:
Alternative
No Action
Air Stripping
Ozone/Hydrogen Peroxide Oxidation
Estimated
-Capital
Cost
($)
0
650,000
1.500.000
Estimated
Annual
O&MCost
ft)
87.500
217.000
287.000
Estimated
Net Present
Worth*
($)
1,350,000
3.990,000
5.910,000
O&M   Operation and maintenance

* Based on 5 percent rate of return and 30-year life.
33537 07.04.00
0314083096 ROD
Harding Lawson Associates

-------
        Table 2.9: Estimated Cost Summary of Selected Remedy • Air Stripping


      Capital Cost
      Direct Capital Cost
        Extraction system                                                       $19,000
        Mobilization and demobilization/site work                                   41,000
        Groundwater treatment system                                            322.000

                                  Subtotal • Estimated Direct Capital Cost          $382,000

      Indirect Capital Cost
        Contingency (@ 25 percent)                                              $96,000
        Engineering (@ 10 percent)                                                38,000
        Contractor markup (@ 10 percent)                                          38,000
        Construction management (@ 25 percent)                                    96.000

                                          Total - Estimated Capital Cost          $650.000
      Annual Operation and Maintenance (O&M) Cost
      Labor and maintenance                                                    $21,000
      Electricity                                                                83,000
      Five-year site review and groundwater monitoring •                             70.000

                                         Subtotal - Estimated O&M Cost          $174,000

      Contingency (@ 25 percent)                                                 43.000

                                      Total Estimated Annual O&M Cost          $217.000
33537 07.04.oo                                       Harding Lawson Associates
0314083096 ROD

-------
                                                           Pacific Ocean
                                                                                      SchofieM
                                                                                    Army Barracks
                                                                                    • East Range
 B
      Schofield x
    Army Barracks
      Main Post
          Explanation

   	Boundary between groundwater bodies

   JH  Scnofield Army Barracks

          Basal Water Body

          Schofield High-tevel Water Body

          Dikenrnpounded Water Body

   KXNJ  Groundwater dam

   i     ,  Generalized cross section line
                  Scale
                                                           10
                                                              Miles
                                                                      Note: Modified from Dale and Takasakl. 1976
                                                                      and Mink and Lau. 1987
                                                                      Cross sections are shown in Figure 2.5.
larding Lawson Accociaas
 ftQMM9IU1Q And
 nvnonmantal SWVK«S
Prepared for:
U.S. Army Environmental Center
Aberdeen Proving Ground, Maryland

Schc field Army Barracks,
Island of Oah-j, Hawaii
Figure 2.1

Regional Groundwater Systems
cf Oahu, Hawaii

-------
                   I
                   c
                   I
                   UJ
Harding Liwton AttocltUt

frvjiiinoiirig and
        lal Services
     Walalua
   Basal Water
      Body
        _\
                                          Honolulu-Peart Harbor
                                             Basal Water Body
                              B
                                                                                                           Walahole Transmission
                                                                                                                   Tunnel
Explanation

Low-permeabllHy rock

Fresh groundwatar

Saline groundwaler

Groundwater flow line
(generalized direction)
                                                                       Scale
                                                                       3
                                                                                                             Miles   Nols: Cross-section lines are shown In Figure 2.4.
                                                                                                                    Modified from Dale and Takasakl, 1976
Prepared (or:
U.S. Army Environmental Center
Aberdeen Proving Ground, Maryland
Schofleld Army Barracks,
Island of Oahu, Hawaii
Figure 2.2

Regional Hydrogeologlc Cross Sections
A-A' and B-B'

-------
                                                                                                                              Schofltld Army Barracks
             fe>-.
Schodsld Army Btrrackt
     Forett Reserve
                                                                                                                                        SchoMM Aimy B«'«tl»
                                                                                                                              Pitpnd lor
                                                                                                                              US KIMIEnvHonminUIC«nMi
                                                                                                                              AbtttfHA Plovlne Oiountf. U«yl»ld

-------
Si ti. >li<-l.| H*|fi ti-ift VV.tliM O.i.|v
    Pf Rfwed lot
    US Anny Environmental Ccntof
    AU'iilrnn PfuvNtq Ground. M.irylaitd

    St;tiolhirracks.
    Island ol Oaliii. Hawaii
    Pfnpnspfl Lnng-Teim
    MotuioiingNoiworh

-------
                                                                                            Discharge to
                                                                                            Atmosphere
                                                                                                t
                                                                                                                                                    en
       Extracted
     Groundwater
                       Pump
                                                                                   Air Stripper
                                                          Treated Water to BWS
                                                           Distribution System
                                                          Blower
                                                  t
                                              Disposal to
                                         Nonhazardous Landfill
                                                        Explanation

                                                   -*•  Liquid stream
                                                                                                                     •*•  Air stream

                                                                                                             1 — — — -^ Nonhazardous disposal

                                                                                                                  BWS  Board of water supply
Harding Lawson Associates
Engineering and
Environmental Services
HLA
Prepared for:
U.S. Army Environmental Center
Aberdeen Proving Ground. Maryland
Schofield Army Barracks,
Island of Oahu, Hawaii
Figure 2.5

Alternative 2 Process Flow Diagram of Air
Stripping OU2 Groundwater Treatment

-------
                                                          Ozone
                                                          Generator
                          Explanation

                      •*•  Liquid stream
                   1 — *•  Air stream

                   ' •- ^ Nonhazardous disposal

                    BWS  Board of water supply
    Extracted
    Groundwater
                       Pump
                                                                                                      Catalytic Ozone
                                                                                                      Decomposer
                                                             Treated Air
                                                            „ Stream
                                                             Discharge
                                                             to Atmosphere
              Ozone/Hydrogen
                  Peroxide
                  Oxidation
                                          Disposal to
                                          Nonhazardous Landfill
                                                                                                                       Treated Water to BWS
                                                                                                                       Distribution System
Harding Lawson Associates
Engineering and
Environmental Services
HLA
Prepared for:
U.S. Army Environmental Center
Aberdeen Proving Ground, Maryland
Schofield Army Barracks.
Island of Oahu,  Hawaii
Figure 2.6

Alternative 4 Process Flow Diagram of
Ozone/Hydrogen Peroxide Oxidation
System for OU2 Groundwater

-------
                             3.0 RESPONSIVENESS SUMMARY



3.1            Overview


This section provides a summary of the public comments and concerns regarding the Proposed Plan at


Schofield Barracks, Island of Oahu, Hawaii. At the time of the public review period, the Army had


selected Alternative 2, as the preferred alternative for the OU 2 groundwater. On the basis of the


written and verbal comments received, the Army's Proposed Plan was generally accepted by the public.



3.2            Background on Community Involvement


The Army has implemented a progressive public relations  and involvement program for environmental


activities at Schofield Barracks. A Technical Review Committee, comprised of representatives from the


Army, the EPA, the State of Hawaii DOH, and members of the general public, has been established and


meets periodically to involve the public in decisions made regarding investigation results, proposed


work, and potential remedial actions. The Army distributed over 100 copies of a fact sheet to interested


parties and to the information repositories (Section 2.6).  These fact sheets described the installation


restoration program at Schofield Barracks, including a discussion of how the public could get more


information and get involved in the program. A synopsis of community relations activities conducted


by the Army is presented in Appendix A.




The Army held a public comment period on the alternatives presented in the OU 2 FS and Proposed


Plan from May 24 through June 24,1996. Over 100 copies of the Proposed Plan were mailed to the


public for review and comment and were placed in the repositories discussed in  Section 2.6.  The


Proposed Plan also invited readers to a public meeting to discuss the preferred alternative. This public


meeting was held to discuss the selected preferred  alternative. The meeting was held on June 12, 1996,


from 7:00 to 8:00 p.m. in the Hale Koa, at Wahiawa District Park, 1139A Kilani Avenue, Wahiawa,


Hawaii.




Comments were received from the public regarding the Proposed Plan public during the comment


period and those comments are addressed below.



33537 07.04.oo                                        Harding Lawson Associates            3-1
0318082396 ROD

-------
Responsiveness Summary
3.3          Summary of Comments Received During Public Comment Period and
             Department of the Army Responses

The comments received during the public comment period and accompanying Army responses are

provided in Appendix B.
3-2          Harding Lawson Associates                                     33537 07.04.00
                                                                       0318082396 ROD

-------
                                      4.0 ACRONYMS
ARAR

Army

bgs

BWS

CERCLA


CFR

COC

COPC

CWA

DERP

DOD

DOH

DOI

EPA

ERA

ESPS

FWS

FFA

gpm

HAR

HC

HI

HLA

HRA

EPR

IRP
Applicable or relevant and appropriate requirement

U.S. Department of the Army

Below ground surface

Board of Water Supply

Comprehensive Environmental Response, Compensation, and Liability
Act

Code of Federal Regulations

Contaminants of concern

Chemicals of potential concern

Clean Water Act

Defense Environmental Restoration Program

U.S. Department of Defense

Department of Health

Department of Interior

U.S. Environmental Protection Agency

Ecological risk assessment

Environmental Services Program Support

U.S. Fish and Wildlife Service

Federal Facility Agreement

Gallons  per minute

Hawaii Administrative Rules

Hawaii Citation

Hazard index

Harding Lawson Associates

Health risk assessment

In-Progress Review

Installation Restoration Program
33537 07.04.00
0308082396 ROD
                      Harding Lawson Associates
4-1

-------
 Acronyms
 Ib/day

 MCL

 MCLG

 NCP

 NGVD

 NMFS

 NPL

 O&M

 OU

 PA/SI

 ppb

 PRG

 RCRA

 RI/FS

 RME

 ROD

 SAP

 SARA

 Schofield Barracks

 SDWA

 TBC

 TCE

 USAEC

 use

 uv

 voc

WES
               Pounds per day

               Maximum Contaminant Level

               Maximum contaminant level goal

               National Oil and Hazardous Substances Pollution Contingency Plan

               National Geodetic Vertical Datum of 1929

               National Marine Fisheries Service

               National Priorities List

               Operation and maintenance

               Operable unit

               Preliminary Assessment/Site Investigation

               Parts per billion

               Preliminary remediation goal

               Resource Conservation and Recovery Act

               Remedial Investigation/Feasibility Study

               Reasonable maximum exposure

               Record of Decision

               Sampling and Analysis Plan

               Superfund Amendments and Reauthorization Act of 1986

               Schofield Army Barracks

               Safe Drinking Water Act

               To be considered

               Trichloroethene

               U.S. Army Environmental Center

               United States Code

               Ultraviolet

               Volatile organic compound

               Waterways Experiment Station
4-2
Harding Lawson Associates
                                                                                 33537 07.04.00
                                                                               0308082396 ROD

-------
                                                                                  Acronyms
Wheeler                     Wheeler Anny Airfield

WWH                       World Warn

jig/m3                       Micrograms per cubic meter

/xg/1                         Micrograms per liter
33537 07.04.oo                                       Harding Lawson Associates            4-3
0308082396 ROD

-------
                                     5.0 REFERENCES


 Dale, R.K., and K.J. Takasaki. 1976. Probable effects of increasing pumpage from the Schqfield
 Groundwater Body, Island ofOahu, Hawaii.  U.S. Geological Survey Water - Resources Investigations
 76-47. Prepared in cooperation with the Board of Water Supply, City and County of Honolulu, Hawaii,
 May.

 Giambelluca, T.W., M.A. Nullet, and T.A. Schroeder. 1986. Rainfall atlas of Hawaii.  Report No. R76.
 Water Resources Research Center, University of Hawaii, June.

 Harding Lawson Associates. 1992a. Final preliminaiy assessment/site investigation report for operable
 units l, 2, and 4, Schofield Army Barracks, Island ofOahu, Hawaii, May 14.

 	. 1992b. Final work plan for the Schofield Barracks remedial investigation/feasibility study,
 October 15.

 	. 1993.  Final sampling and analysis plan for operable unit 2 phase I remedial investigation,
 Schofield Army Barracks, Island of Oahu, Hawaii.

 '	. 1995a. Final sampling and analysis plan for operable unit 4 phase n remedial investigation and
feasibility study field program, Schofield Army Barracks, Island of Oahu, Hawaii, March 16.

 	. 1995b. Final remedial investigation report for operable unit 1, Schofield Army Barracks, Island
 ofOahu, Hawaii, April.

 	. 1995c. Final sampling and analysis plan for operable unit 2 phase n remedial investigation,
 Schofield Army Barracks, Island of Oahu, Hawaii, April.

 	. 1996a. Final feasibility study report for operable unit 2, Schofield Army Barracks, Island of
 Oahu, Hawaii, May.

 	. 1996b. Draft Final operable unit 2 remedial investigation report, Schofield Army Barracks, May.

 Mink, J. F.. and S. L. Lau.  1987. Aquifer identification and classification for Oahu: Groundwater
protection strategy for Hawaii. Technical Report No. 179. Water Resources Research Center, University
 of Hawaii, November.

 R.M Towill Corporation. 1977. Analysis of existing facilities, Schofield Barracks: U.S. Army Corps of
Engineers, Pacific Ocean Division, December.

 U.S. Army Pacific Environmental Health Engineering Agency. 1977. Water quatity engineering special
study (W2J no. 94-001-77, surface-water study in support of environmental impact statement for
 U.S. Army Support Command, Hawaii,  Oahu, Hawaii. Phase Two, March 10 - April 22.

U.S. Army Support Command, Hawaii. 1983. Secretary of the Army environment quality award.
Personal communication with Harding Lawson Associates.

U.S. Environmental Protection Agency. 1993. Presumptive Remedy for CERCLA Municipal T^nHfil]
Sites, September.

	.  1995.  Region Kpreliminary remediation goals (PRGs), first half 1995; February 1.

U.S. Environmental Protection Agency (Region DC),  The State of Hawaii, and the U.S. Department of the
Army. 1991. Schofield Barracks federal facility agreement, August.


33537 07.04.oo                                       Harding Lawson Associates            5-1
0307082996 ROD

-------
                 Appendix A



SYNOPSIS OF COMMUNITY RELATIONS ACTIVITIES

-------
                                                                                     Appendix A
May 1985 - Schofield Barracks issued a press release regarding the detection of Trichloroethylene (TCE)
in the Schofield Barracks Supply wells and the temporary switch to city and county water supplies.

August 1990 • Schofield Barracks issued a press release regarding the placement of the installation on
the National Priorities List (NPL).

October 1990 - Schofield Barracks Public Affairs Office and Environmental Office addressed the
Wahiawa Neighborhood Board regarding Army plans to conduct investigations on Schofield Barracks to
identify sources of TCE.
                                                                                        *•
January 1992 - Schofield Barracks and U.S. Army Toxic and Hazardous Materials Agency
(USATHAMA) submitted press releases requesting public involvement in locating the source(s) of TCE
contamination in and around Schofield Barracks.

January 1992 • Schofield Barracks and USATHAMA conducted interviews with twenty local residents
to assist in the development of a Community Relations Plan for the Schofield Barracks Installation
Restoration Program (IRP).

June 1992 - The Army finalized the Community Relations Plan for Schofield Barracks and placed copies
in the newly established information repositories located in the Milliard Public Library, the Wahiawa
Public Library, The Hawaii Department of Health, and the Directorate of Public Works in Building 300
of Wheeler Army Airfield.

February 25,1993 - Schofield Barracks and the Army Environmental Center (AEC) conducted a public
meeting at the Hale Koa at Wahiawa District Park in Wahiawa to provide the public with an update on
the IRP and the results of the first phase of the investigations.

February 1993 - In conjunction with the public meeting, the Army published and distributed a fact
sheet that provided an update on the IRP and initial investigative results.

September 13 and 14,1994 - Schofield Barracks and the AEC conducted public availability sessions at
the Hale Koa at Wahiawa District Park (September 13) and at the Schofield Barracks Post Library
(September 14) to provide an update on the IRP.

September 13 and 14,1994 - In conjunction with the public availability sessions, the Army solicited
interest in the formation of a Restoration Advisory Board (RAB) comprised of local citizen representa-
tives, Army representatives, and regulatory agency representatives that would oversee the conduct of
the Army's IRP at Schofield Barracks.

September 12 through 14,1994 - The Army presented a poster display that summarized installation
restoration efforts and plans for Schofield Barracks at the 1st Hawaii National Technologies Conference
sponsored by the Hawaii Department of Health

September 1994 - In conjunction with the public availability session, the Army published and
distributed a fact sheet that provided an update on the IRP and initial investigative results.

May 24 throughjune 24.1996 - Schofield Barracks conducted a public review period for the Proposed
Plan for Operable Unit 2.

June 12,1996 - Schofield Barracks and the AEC conducted a public meeting to present the Operable
Unit 2 Proposed Plan and solicit public comments.
33537 070400                                        Harding Lawson Associates               A-1
0927083096 ROD

-------
                             Appendix B



COMMEKTS RECEIVED DURING PUBLIC COMMENT PERIOD AND ARMY RESPONSES

-------
Directorate of Public Works                       -            MS 0 9
Mr. Henry Curtis
Executive Director
Life of the Land
1111 Bishop Street
Suite 503
Honolulu, Hawaii 96813

Dear Mr. Curtis:

    Thank you for your input on the Army's Proposed Plan for addressing ground water contamination at
Schofield Barracks.

    In response to your comment regarding the detection levels used in monitoring water supply wells
under the Schofield Barracks installation restoration program, the Army, in the past has used an
analytical method that will accurately detect trichloroethylene (TCE) down to 1.0 micrograms per liter
(ug/1) or parts per billion (ppb).  This provides an adequate safety factor between the detection limits and
the Safe Drinking Water Act Maximum Contaminant Level of 5 ug/l. In addition, the Army recently
agreed to a request by the Hawaii Department of Health to use a drinking water analytical method that
will detect TCE down to 0.3 ug/1 for all future sampling to be conducted under the proposed wellhead
treatment remedial action.

    We would like to assure you that the approach in the Operable Unit 2 Proposed Plan for addressing
the groundvvater contamination is fully protective of human health and the environment. The Army is
committed to ensuring that the water supply wells potentially impacted by the TCE originating from
Schofield Barracks are monitored and that actions are taken if TCE is found in those supply wells.

    Your participation in the OU 2 Proposed  Plan Public meeting was appreciated. Your continued
interest in the cleanup efforts at Schofield Barracks is encouraged, and if you have any further questions,
please contact Mr. Jon Fukuda, Environmental Department, Directorate of Public Works, 656-6790.

                                                Sincerely,
                                               Dennis J. Fontana
                                               Colonel, U.S. Army
                                               Director of Public Works

-------
                        LIFE   OF   THE   LAND
                        HAW AITS OWN  ENVIRONMENTAL ACTION  GROUP
                        EDUCATION, RESEARCH, LOBBYING &  LITIGATION
                        PROTECTING  HAWAITS   FRAGILE  ENVIRONMENT
 June 21, 1996


         . Comments RE: Operable Unit 2: Ground water
The facts are simple. TCE exists in the groundwaier. The Army/EPA has spent $8M looking for the
source, unfortunately unsucessfully. The Army has removed an equivalent of I drum (55 gallons) of
TCE per year from groundwater filtration for the past 10 years.

The City & County of Honolulu's Board of Water Supply (BWS) maintains five separate water
systems for Oaliu. They are:
                   Waialua—Haleiwa-Sunset;
                   Waianae—Ewa—Downtown-East Honolulu—Windward
                   Wahiawa;
                   Mililani;
                  • Kunia.
The fiction is that everything is okay. The BWS has monitored wells for pesticide and toxic
contamination for many years. Persistent critics outside of the government, and sources within the
BWS have slated that the BWS tests leave a lot to be desired. If contamination is found in a well,
either the detection level for a test will be lowered (if 3 ppb was detected, the next testing will only be
able to measure 5 ppb), or the well will no longer he tested.

There is a disease cluster in Village Park. Many believe that the contamination is in the ground water
or the soil. The Hawaii Department of Health has testified before the State Legislature that they would
investigate — if the had the $ — but since they don't — other priorites come first.

The EPA came out to Oahu last fall to obtain information about the  proposed Kunia Superfund
site.The EPA asked  Life of the Land for input. The EPA wanted to limit the Kunia.Superfund to
Kunia. The EPA did  not want  the Proposed Kunia Superfund Sue to  overlap with the Schofield
Superfund Site. Too many complications!

The GaJbraith property has been proposed as the site for the joint VVahiawa/Schofield  Wastewatei
Treatment Plant and Wetlands Facility.  This would require separating the Schofield Superfund Site
into sections, and (hen de-listing the Galbraiih section.

These examples lead the environmental community 10 question the message we are receiving.
      1111 Bishop St, Suite 503 • Honolulu, HI 96813 • 533-3454 • fax 533-0993

-------
In this case, the community,  through participation in the RAB  process, can  feel assurred that
everything is under control. The community would also feel comfortable knowing that if conditions
change, they would know about the changes up-front. The military could also profit greatly from this
continued interaction with the community.

Life of the Land is interesting in serving on such a Board.
Henry Q Curiis
Executive Director

-------
     O'AHU GROUP
     SIERRA CLUB/HAWAI'I CHAPTER
     P.O. Box 2577, Honolulu, Hawaii 96803
     Phone:(808)538-6616
                          June 18,  1996
Commander
USAG-HI
Directorate of Public Works
Attn:  Mr. John Fukuda
Schofield Barracks HI  96857-5000

Dear Mr. Fukuda/

     The Oxahu Group of the Sierra Club  is concerned that the
proposed plan to address groundwater contamination at Schofield
does not appear to call for the long-term cleanup of site
contamination and restoration of the groundwater  system.   While
it may be cost-effective in the short-term to treat water before
consumption, it is imperative that the sources of contamination
be identified and cleaned up.            .
                                   Sincerely,
                                   PHILIP D. BOG
                                    Oahu Group Chair,
                                    Hawaii Chapter,
                                    Sierra Club
                                                             100% Recycled Paper

-------
 Directorate of Public Works                        -                              !:"[1
Mr. Phillip D. Bogetto
O'ahu Group Chair
Hawaii Chapter
Sierra Club
P.O. Box 2577
Honolulu, Hawaii  96803

Dear Mr. Bogetto:

    Thank you for your input on the Army's Proposed Plan for addressing groundwater contamination at
Schofield Barracks.

    The Army shares your opinion that the best approach for protecting and restoring groundwater is to
identify and cleanup sources of contamination. The Army's highest priority under the installation
restoration program was the identification and investigation of potential sources of the solvent
trichloroethylene (TCE) which resulted in contamination of the groundwater underlying the installation.
A thorough investigation was conducted under Operable Unit 1 (TCE sources) to determine the source,
or sources, of TCE contamination. The investigation included extensive historical records search,
interviews with past employees, an extensive review of historical aerial photographs and site walks to
identify potential source areas. This was followed by a remedial investigation of those sites which
included  soil gas surveys to detect the smallest presence of TCE and other contaminants. Unfortunately,
that search failed to identify a source of contamination. As discussed at the Operable Unit 1 public
meeting on July 18, 1995, the Army has followed up on all information regarding possible TCE sources
and will continue to do so, however, at this time we have investigated all suspected sites.

    We would like to assure you that the approach proposed under the Operable Unit 2 Proposed Plan is
fully protective of human health and the environment. The Army is committed to ensuring that the water
supply wells potentially impacted by the TCE originating from Schofield Barracks are monitored and
that actions are taken if TCE is found in the supply wells.

-------
                                               -2-
    Your continued interest in the cleanup efforts at Schofield Barracks is encouraged, and if you have
any questions, please contact Mr. Jon Fukuda, Environmental Department, Directorate'of Public Works
656-6790.                                                                                    '

                                               Sincerely,
                                             ^ Dennis J. Fontana
                                               Colonel, U.S. Army
                                               Director of Public Works

-------
                   HOUSE OF REPRESENTATIVES

                             STATE OP HAWAII
                              STATE CAPITOL
 Marcus R.Oshiro               HONOLULU. HAWAII 96813              Dislricl 40
Slate Representative                                          Wahiawa Whitmwe Village
                              June 20. 1996
Commander
U.S. Army Garrison - Hawaii
Directorate of Public Works
ATTN: APVG-GWV (Mr. Jon Fukuda)
Schofield Barracks. Hawaii 96857-5000

Dear Commander:

                        RE: OU2 Public Comments

Please accept the following as my written comments to the proposed clean up
plans for Operable Unit 2 (OU2). My concerns regarding the proposed
alternative are as follows:

1     Source of carbon tetrachloride and TCE has not  been identified.

      I have concerns regarding the integrity of the Risk Assessment; How can
      one measure the risk of danger to health and environmental when there is
      no knowledge of the extent of contamination? Do you have any best
      estimates of the quantity of contamination? Can this be deduced from
      past records, oral investigations of past personnel? More resources
      should be directed to ascertaining the extent of and quantity of
      contamination.

2     Protection of Public Water Supply.

      I have grave concerns over the current monitoring process, especially
      given the close proximity of Board of Water Supply wells and water
      sources of the contaminated groundwater beneath Schofield. If the
      contaminated body of groundwater should move from it present site,
      would it not expose the public water supply to contamination also?

-------
OU2
June 20, 1996
Page 2
      I would like clarification on the safeguards currently established.
      Likewise, clarification of the safeguards being taken to insure that the
      larger groundwater body is not contaminated.

I wish to obtain a copy of the map of the test sites and the corresponding levels
of contaminants found in each (This was the visual aid used at the Public
Meeting).

I thank you for the opportunity to comment. If you have any questions or if I can
be of any further assistance, please feel free to contact me at 586-8505.

                             Very truly yours.
                              MARCUS R. OSHIRO
                              State Representative
MO:gt

-------
                                  DEPARTMENT OF THE ARMY
                         HEADQUARTERS. UNITED STATES ARMY GARRISON. HAWAII
                                SCHORELD BARRACKS, HAWAII 96857-5000
           REPLY TO
           ATTENTION OF
                                       August  30, 1996
Directorate of Public Works
Honorable Marcus R. Oshiro
State Representative
District 40   -
State of Hawaii
State Capitol  '                                                      .          .           •*r
Honolulu, Hawaii  96813

Dear Mr. Oshiro:

    I would like to thank you for the interest you have shown in the Army's clean-up program at
Schofield Barracks and for your .comments on the Operable Unit 2 (Groundwater) Proposed Plan
provided in your letter of June 20,1996. The following information is provided in response to your
comments:

    Comment 1: Source of carbon tetrachloride and TCE has not been identified.

    Response: The Army shares your concern that the source of the TCE plume from the East Range
Area has not been specifically identified.  The Army's highest priority under the installation restoration
program was the identification and investigation of potential sources of the solvent trichloroethylene
(TCE), which resulted in contamination of the groundwater underlying the installation. The best
approach for protecting and restoring groundwater is to identify and clean up sources of contamination.
A thorough investigation was conducted under Operable Unit 1  (TCE Sources) to determine the source
or sources of TCE contamination. The investigation included extensive historical record searches,
interviews with over 120 people, an extensive review of historical aerial photographs (120 photographs
dating back to the 1940's), and site walks to identify potential source areas.  This was followed by a
remedial  investigation of those sites, which included soil gas  surveys to detect the smallest presence of
TCE in the soils, soil sampling to depths of 150 feet, stream and sediment sampling, geophysical surveys
to locate past disposal trenches, and various other techniques  to determine the presence of TCE and other
contaminants.  Unfortunately, that search  failed to identify a source of contamination. As discussed at
theOperable Unit I public meeting on July IS. 1995, the Army has followed up  on all information
regarding possible TCE sources. However, at this time, we have investigated all suspected sites.

   The risk assessment conducted for the groundwater contamination at Schofield Barracks was
performed using the highest concentration of TCE recorded in the groundwater at the East Range.  These
levels are much higher than those currently found in the Schofield Supply wells, and are much higher
than could potentially migrate to other municipal water supply wells downgradient of Schofield
Barracks.  Natural processes of dilution, absorption and degradation will continue to  reduce TCE
concentrations as the groundwater moves  away from ihe Schofield area.

-------
                                              -2-
    Even using the highest concentrations, the grouiidwater risk assessment showed no unacceptable risk
from consumption of the untreated groundwater. Regardless of the risk, the Army is obligated under
Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) to address
groundwater contamination based on the exceedance of Safe Drinking Water Act Maximum
Contaminant Levels (MCLs) under the Safe Drinking Water Act for TCE and carbon tetrachloride.  The
proposed plan for Operable Unit 2 addresses the contamination through long-term monitoring of the
supply wells,
-------
Estimated	
SeholhkJ Hlgh-lqvd Water Body
  Piopoied Long-letm Giounflwnlci
  Monilorioy Nolwoih

-------
                       Appendix C



ANALYSIS OF THE IMPACT OF TRICHLOROETHENE ON CARBON USAGE

-------
	Appendix C


  ANALYSIS OF THE IMPACT OF TRICHLOROETHENE (TOE) ON CARBON USAGE IN THE
             HONOLULU BOARD OF WATER SUPPLY TREATMENT SYSTEMS


HLA contacted both Carbonaire and Calgon and asked each of the companies to model the possible

effects of TCE on the groundwater that is currently being treated at the Board of Water Supply's

Mililani I and Mililani n systems. Table 1 was provided to both companies. Both companies were

asked to model the effects of a range of TCE concentrations (0.5 micrograms per literfrig/l), 1.0 /ig/1,

2.0 ng/l, 3.0 Mg/l 5.0 Mg/1.10.0/ig/l. 15.0 /ig/1 and 25 jtg/1) on carbon usage if the treatment system

influent contained the highest contaminant concentrations listed for each chemical on Table 1 (3.0 ngfl

of 1,2,3-trichloropropane (TCP), 0.9 ng/l 1,2-Dichloropropane (DCP) and l,2-Dibromo-3-chloropropane

(DBCP)) and the TCE concentrations in the effluent were not to exceed 2.5 jig/1.



Carbonaire could not model a multicpmponent system where the least adsorbable compound (i.e., TCE)

was not the driver (compound driving the usage rate). However, Carbonaire estimated that TCE would

only have a minor affect on the adsorption of TCP. Calgon was able to model a multi-component

system using a proprietary program developed for Calgon. The program is based on Polyani Adsorption

Theory and incorporates the modification of the theory proposed by Hansen and Fackler. The theory

and equations were derived from the first principals of thermodynamics. The effects of competive

adsorption between the identified species are considered when determining the total capacity of the

GAC and the composition of the adsorbate mixture that fills the carbon.



The principals and assumptions incorporated into the model were given by Calgon as follows:


•      All adsorbates gave equal access to all sites. This limits the model because molecular sieving
       can exclude certain molecules because of size or shape.

•      The possibility of chemisorption is not considered. ChemiSQiption generally occurs when
       carbon acts as a catalyst causing a chemical reaction to occur when certain chemicals come into
       contact with carbon .  The compound that reacts with the carbon may then react with the
       contaminant of concern that you are trying to remove from your water and change the
       contaminant of concern in such a way that it will no longer adsorb to the carbon.

•      The adsorbates compete for adsorption sites on a volume basis, so a large molecule displaces an
       equal volume  of small molecules.
33537 07.04.oo                                       Harding Lawson Associates          C-1
07188/30/96 ROD

-------
Appendix C	


•      The molecule having adsorption with the greatest thermodynamic driving force will displace or
       prevent adsorption of other molecules at a specific site.


The modeling results from Calgon are presented in Table 2 to for Mililani I and Mililani ffl systems.

The modeling results indicate that the carbon usage rate will go up as the concentrations of TCE

increase from 0.5 Mg/1 to 5.0 /ig/1 indicating that the U.S. Army would be responsible for sharing some

carbon usage costs at concentrations ranging between the detection limit and 2.5 ngf\. However,

additional cost for carbon usage would not be high enough to warrant installation of the air stripper

prior to TCE concentrations reaching 2.5 /xg/1.
                             Harding Lawson Associates                  33537 07.04.00
                                                                              08308/30/96

-------
         Table 1:  Honolulu Board of Water Supply Chemical Laboratory Report
 Subject*
Trihelomethanes/Volatile Organic Chemicals Test Results
                                            Sample Source
Compound
Mililani
Wells 1
GAC Cent #11
Mililani
Wells 1
Pump #3
Mililani
Wells 1
Pump. #4
Detection
Limit
(MS/1)
EPA
MCL
(MS/1)
 1,2-Dichloropropane (DCP)         0.9             0.7          0.8
 1,2,3-Trichloropropane (TCP)       0.2             3.0          2.2
 1,2-Dibromo 3-Chrloropropane     <0.01          0.10         0.14
 (DBCP)
 1,2-Dibromethane (EDB)           <0.0l          <0.0l        <0.01

 Date Sampled:                   10/18/95        10/17/95      10/17/95
 Date Received:                   10/20/95        10/20/95      10/20/95
 Date Analyzed:                   10/25,26/95     10/25/95      10/25/95
 Lab ID No.:                      951020028      951020021    951020022
                                                             0.1
                                                             0.1
                                                             0.01

                                                             0.01
3
0.8*
0.04'

0.04 *
     State DOH MCL
28339 07.04.00
07188/23/96 CEA
                                  Harding Lawson Associates

-------
          Table 2: Estimated Increase in Cartoon Usage at Mililani I and Mililani II Systems
TCE
Influent
fctt/1)
Mililanil
0.5
1
2
3
5
10
15
25
Mililanfll
0,5
1
2
3
5
10
15
25
TCE
Effluent
tttg/I)

0.5
1
2
2.5
2.5
2.5
2.5
2.5

0.5
1
2
2.5
2.5
2.5
2.5
2.5
Estimated
Annual
Carbon, Usage*
flba/yr)

240,000
240,000
240,000
240,000
240,000
240,000
240,000
240,000

80,000
80,000
80,000
80,000
80,000
80,000
80,000
80,000
Percent Increase
of Annual
Carfaonb
Usage Rate

<1
4
8
12
23
46
62
96

<1
4
8
12
23
46
62
96
Carbon
Replacement
and Disposal Cost*
r$/ib)

$1.70
$1.70
$1.70
$1.70
$1.70
$1.70
$1.70
$1.70

$1.70
$1.70
$1.70
$1.70
$1.70
$1.70
$1.70
$1.70
Annual Increase in
Carbon
Replacement
and Disposal Cost

Approx $4,100.00
$16,320.00
$32,960.00
$48,960.00
$93,840.00
$187,680.00
$252.960.00
$391,680.00

Approx.$l, 400.00
$5,440.00
$10,880.00
$16,320.00
$31,280.00
$62,560.00
$84,320.00
$130,560.00
 a.   Estimated annual carbon usage rates and carbon replacement and disposal cost were provided by Honolulu Board
     of Water Supply.
 b.   Percent increase of annual carbon usage rate if TCE impacts B WS carbon treatment system was provided by Calgon
     using their proprietary multicomponent computer model.
 28339 07.04.00
. 07188/30/96 CEA
Harding Lawson Associates

-------