PB96-964413
                                 EPA/ROD/R08-96/115
                                 October 1996
EPA  Superfund
       Record of Decision:
       Ellsworth Air Force Base,
       Operable Unit 12, Rapid City, SD
       5/10/1996

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                 Final

         Record of Decision for
  Remedial Action at Operable Unit 12
Ellsworth Air Force Base, South Dakota
          United States Air Force
          Air Combat Command
          Ellsworth Air Force Base
               April 1996
                         Air Force Project No. FXBM 94-7002

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                                              Final Record of Decision Operable Unit 12
                                                Ellsworth Air Force Base, South Dakota
                           TABLE OF CONTENTS

Chapter       •                                                       Page

1.0 DECLARATION FOR THE RECORD OF DECISION	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	1-1
   1.4 DESCRIPTION OF SELECTED REMEDY	1-1
   1.5 STATUTORY DETERMINATION	;	1-2
   1.6 SIGNATURE AND AGENCY CONCURRENCE ON THE REMEDY	1-3

2.0 DECISION SUMMARY	2-1

   2.1 SITE NAME AND LOCATION	2-1
   2.2 OPERABLE UNIT 12 (OU-12) DESCRIPTION/HISTORY AND
       REGULATORY OVERSIGHT ACTIVITIES	2-1
       2.2.1   Description/History	2-1
       2.2.2   Regulatory Oversight Activities	2-2
   2.3 HIGHLIGHTS OF COMMUNITY PARTICIPATION	2-3
   2.4 SCOPE AND ROLE OF RESPONSE ACTION	2-4
   2.5 SITE CHARACTERISTICS	2-5
       2.5.1   Soils	2-5
       2.5.2   Sediment	2-6
       2.5.3   Ground Water	2-6
       2.5.4   Surface Water	2-7
   2.6 SITE RISK SUMMARY	2-8
   2.7 DESCRIPTION OF ALTERNATIVES	2-11
   2.8 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES	2-12
       2.8.1   Overall Protection of Human Health and the Environment	2-12
       2.8.2   Compliance with ARARs	-.	2-13
       2.8.3   Long-Term Effectiveness and Permanence	2-14
       2.8.4   Reduction of Toxicity, Mobility, and Volume Through Treatment 	2-15
       2.8.5   Short-Term Effectiveness	2-15
       2.8.6   Implementability	2-16
       2.8.7   Cost	:	2-16
       2.8.8   State Acceptance	2-18
       2.8.9   Community Acceptance	:	2-18
   2.9    SELECTED ALTERNATIVE	2-18
   2.10STATUTORY DETERMINATIONS	2-21
       2.10.1  Protection of Human Health and the Environment	2-21
       2.10.2  Compliance with ARARs	2-21
       2.10.3  Cost Effectiveness	2-22
                     TABLE OF CONTENTS (continued)
                                                                   Apnl 1996

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                                                    Final Record of Decision Operable Unit 12
                                                      Ellsworth Air Force Base, South Dakota
        2.10.4  Utilization of Permanent Solutions and Alternative Treatment
                Technologies to the Extent Possible	2-22
        2.10.5  Preference for Treatment as a Principal Element	2-22

     2.11 DOCUMENTATION OF SIGNIFICANT CHANGES	2-22

 3.0  LIST OF ACRONYMS AND ABBREVIATIONS	3-1


                                   APPENDICES

 Appendix A     Figures
 Appendix B      Responsiveness Summary
                                 LIST OF FIGURES

Figure 2-1       Area Location Map
Figure 2-2       Site Map
Figure 2-3       Operable Unit 12
Figure 2-4       OU-12 Potentially Affected Wetlands
Figure 2-5       Operable Unit 12 Area of Attainment
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                                                     Final Record of Decision Operable Unit 12
                                                       Ellsworth Air Force Base, South Dakota
                1.0  DECLARATION FOR THE RECORD OF DECISION

 1.1 SITE NAME AND LOCATION

     •   Operable Unit 12 (OU-12), Hardfill No. 1, Ellsworth Air Force Base (EAFB), National
         Priorities List Site.
     •   Meade and Pennington Counties, South Dakota

 1.2 STATEMENT OF BASIS AND PURPOSE

 This decision document describes EAFB's selected remedial action for OU-12, 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 the National Oil and Hazardous Substances Pollution Contingency Plan (NCP).

 This decision is based on the contents of the Administrative Record for OU-12, EAFB. The U.S.
 Environmental Protection Agency (EPA) and the South Dakota Department of Environment and
 Natural Resources (SDDENR) concur with the selected remedial action.

 1.3 ASSESSMENT OF THE SITE

 Actual or threatened releases of hazardous substances from OU-12, if not addressed by
 implementing the response action selected in this Record of Decision (ROD), may present an
 imminent and substantial endangerment to public health, welfare, or the environment.

 1.4  DESCRIPTION OF SELECTED REMEDY

 Twelve potentially contaminated areas, or operable units,  have been identified at EAFB. This
 ROD is for a remedial action at OU-12 (Hardfill No. 1, approximately  14 acres) and is the ninth
 ROD for EAFB

 The selected alternative, capping, includes the following major components:

 •    Placing a soil cover capable of sustaining perennial vegetation over the hardfill area;

 •    Pre-design study to identify the source of methane and examine the need for hardfill gas
     control measures, and evaluate the need for erosion control measures along the stream
   - adjacent to the hardfill areas;

 •    Institutional controls for the hardfill areas;

 •   Long-term monitoring;

 •   Long-term maintenance of soil cover.

 Implementation of the remedy will reduce the future risk to human health and the environment to
 acceptable levels.

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                                                        Final Record of Decision Operable Unit 12
                                                          Ellsworth Air Force Base, South Dakota
 1.5 STATUTORY DETERMINATION

 The selected remedy is protective of human health and the environment, complies with Federal
 and the State of South Dakota requirements that are legally applicable or relevant and appropriate
 to the remedial action and is cost-effective.  This remedy utilizes permanent solutions and
 alternative treatment (or resource recovery) technologies, to the maximum extent practicable for
 OU-12. However, because treatment of the principal threats of the OU was not found to be
 practicable, this remedy does not satisfy the statutory preference for treatment as a principal
 element.  The large size of the hardfill and the fact that there are no apparent on-site hot spots that
 represent major sources of contamination preclude a remedy in which contaminants could be
 excavated and treated effectively.

 Because this remedy will result in  hazardous substances remaining on-site beneath the hardfill
 cover area, a review will be conducted no less often than every five years after signing of the
 ROD to ensure that the remedy continues to provide adequate protection of human health and the
 environment.
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                                                  Final Record of Decision Operable Unit 12
                                                    Ellsworth Air Force Base, South Dakota
 1.6  SIGNATURE AND AGENCY CONCURRENCE ON THE REMEDY
 BRETT M. DULA                             Date
 Lieutenant General, USAF
 Vice Commander
 JACKW. MCGRAW                            Date
 Acting Regional Administrator
 U.S. Environmental Protection Agency Region 8
NETTIE H. MYERS, Secretary                    Date
Department of Environment and Natural Resources
State of South Dakota
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                                                  Final Record of Decision Operable Unit 12
                                                    Ellsworth A ir Force Base. South Dakota
 1.6 SIGNATURE AND AGENCY CONCURRENCE ON THE REMEDY
BRETT M. DULA
Lieutenant General, USAF
Vice Commander
                                                           Date
JACK W. MCGRAW
Acting Regional Administrator
U.S. Environmental Protection Agency Region 8
                                                           Date
NETTIE H. MYERS, S
Department of Enviro
State of South Dakota
                                                           Date
                         nd Natural Resources
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                                                      Final Record of Decision Operable Unit 12
                                                         Ellsworth Air Force Base, South Dakota
                              2.0 DECISION SUMMARY

 2.1 SITE NAME AND LOCATION

 EAFB is a U.S. Air Force Air Combat Command (ACC) installation located 12 miles east of
 Rapid City, South Dakota, and adjacent to the small community of Box Elder (Figure 2-1).

 EAFB covers approximately 4,858 acres within Meade and Pennington counties and includes
 runways and airfield operations, industrial areas, and housing and recreational facilities (Figure 2-
 2). Open land, containing a few private residences, lies adjacent to EAFB on the north, south,
 and west, while residential and commercial areas lie to the east of the Base.

 2.2 OPERABLE UNIT 12 (OU-12) DESCRIPTION/HISTORY AND REGULATORY
     OVERSIGHT ACTIVITIES

 2.2.1   Description/History

 Ellsworth Air Force Base (EAFB) was officially activated in July 1942 as the Rapid City Army
 Air Base,  a training facility for B-17 bomber crews. It became a permanent facility in 1948 with
 the 28th Strategic Reconnaissance Wing as its host unit. Historically, EAFB has been the
 headquarters of operations for a variety of aircraft, as well as the Titan I Intercontinental Ballistic
 Missile, and the Minuteman I and Minuteman n missile systems. The Air Force has provided
 support, training, maintenance, and/or testing facilities at EAFB. Presently, the 28th
 Bombardment Wing (B-1B bombers) is the host unit of EAFB.

 OU-12 is located in the southern half of EAFB, immediately north of the Alert Apron and
 southwest of the Primary Instrument Runway (Figure 2-3).  OU-12 is the area designated as
 Hardfill No. 1 which is approximately 14 acres in size. OU-12 was identified as a hardfill, rather
 than a landfill, because disposal records indicated that it only received construction debris such as
 wood, metal, concrete, and asphalt.   An unnamed ephemeral drainage channel runs through  the
 center of the hardfill which carries surface water runoff from the Base storm water management
 system.  Storm water from taxiways, runways, and operations areas along the South Dock drain
 into this ephemeral drainage. The water in the drainage channel flows south to a ponded area in
 the center of the hardfill, and then southwest, around the Alert Apron, past OU-1, into Pond 001,
 and ultimately off-Base.

 Historical  aerial photographs indicate the area has been used for dumping of construction debris'
 such as wood, metal, concrete, and asphalt since the 1940s. Construction debris is visible over
 portions of OU-12, although much of the former disposal area is covered by vegetation.
 Disposal of hazardous materials has not been documented at OU-12; however, the area was
 designated as an operable unit based on historical disposal practices at the Base.
 The topography at OU-12 is characterized by a north-south unnamed, unlined ephemeral drainage
 channel through the center of the hardfill which carries surface water runoff from taxiways,
 runways, and other operations  areas.  Surface topography at OU-12 generally slopes toward the
 ephemeral stream. Hardfill areas encroach upon the east bank of the drainage channel and also
 serve as riprap in some places.  The hardfill boundaries extend to the south, beneath the present-
 day Alert Apron. The drainage channel contains wetlands which are illustrated on Figure 2-4.

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                                                       Final Record of Decision Operable Unit 12
                                                         Ellsworth Air Force Base, South Dakota
 The shallow aquifer at EAFB is considered a potential drinking water source and possibly
 discharges to the surface. The ground water is classified as having a beneficial use as a drinking
 water supply suitabje for human consumption (ARSD Chapter 74:03:15, Groundwater Quality
 Standards).

 Deeper bedrock aquifers also exist beneath EAFB. These deeper aquifers are separated from the
 shallow aquifer by 800 feet of low-permeability clays and silts. In the past, EAFB utilized these
 deeper aquifers for its water supply.  Presently, EAFB obtains its potable water from the Rapid
 City Municipal Distribution System.

 2.2.2    Regulatory Oversight Activities

 Environmental investigation activities at EAFB were initiated by the Air Force in 1985 through an
 Installation Restoration Program (IRP) Phase I Installation Assessment/Records Search and Phase
 H, Confirmation/Quantification. The Phase I study, dated September, 1985, identified a total of
 17 locations at EAFB where releases involving hazardous substances potentially occurred.

 In Phase II, of the IRP investigation, field activities included soil vapor surveys, geophysical
 surveys, surface and subsurface soil sampling, ground-water sampling, ground-water hydrologic
 testing, and ecological investigations.

 On August 30, 1990 (55 Federal Register 35509), EAFB was listed on the U.S. EPA's National
 Priorities List (NPL). A Federal Facilities Agreement (FFA) was signed in January 1992 by the
 Air Force, the  U.S. Environmental Protection Agency (EPA), and the State of South Dakota
 (SDDENR) and went into effect on April 1, 1992. The FFA establishes a procedural framework
 and schedule for developing, implementing, and monitoring appropriate response actions for
 EAFB 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 the National Oil and Hazardous Substances Pollution
 Contingency Plan (NCP). It also states the oversight procedures for EPA and the State to ensure
 Air Force compliance with the specific requirements. The FFA identified 11 site-specific operable
 units (OUs) and a Base-wide ground-water operable unit.  The Base-wide ground-water OU is
 primarily used  to address contaminated ground water that was not addressed during the
 investigation of a site-specific OU.

 Listing on the NPL and execution of the FFA required  the U.S. Air Force to perform a remedial
 investigation/feasibility study (RI/FS) to investigate the 12 operable units. In 1993 and 1994, an
 extensive RI field program was conducted to characterize conditions at OU-12. The program
 included: drilling and of boreholes, installation of monitoring wells, geotechnical analysis  of soil
 samples, ecological evaluation, assessment of human health risks, and review and compilation of
 previous IRP investigations. Collection and laboratory analysis of soil, ground-water, surface
 water, and sediment samples were included in the RI field program.

 2.3 HIGHLIGHTS OF COMMUNITY PARTICIPATION

 Community relations activities that have taken place at EAFB to date include:

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                                                      Final Record of Decision Operable Unit 12
                                                        Ellsworth Air Force Base, South Dakota
     •   FFA process. After preparation of the FFA by the USAF, EPA, and SDDENR, the
         document was published for comment. The FFA became effective April 1, 1992.

     •   Administrative Record. An Administrative Record for information was established in
         Building 8203 at EAFB. The Administrative Record contains information used to
         support USAF decision-making. All the documents in the Administrative Record are
         available to the public.

     •   Information repositories. An Administrative Record outline is located at the Rapid City
         Library (public repository).

     •   Community Relations Plan (CRT). The CRP was prepared and has been accepted by
         EPA and the State of South Dakota and is currently being carried out. An update to this
         plan will be prepared in 1996.

     •   Restoration Advisory Board (RAB). The RAB has been formed to facilitate public
         input in the cleanup and meets quarterly. In addition to USAF, EPA, and  South Dakota
         oversight personnel, the RAB includes community leaders and local representatives from
         the surrounding area.

     •   Mailing list. A mailing list of all interested parties in the community is maintained by
         EAFB and updated regularly.

     •   Fact sheet.  A fact sheet describing the status of the IRP at EAFB was distributed to the
         mailing list addressees in 1992.

     •   Open house. An informational meeting on the status of the IRP and other environmental
         efforts at EAFB was held on May 6, 1993.  An open house was held November 16, 1995
         in conjunction with the Restoration Advisory Board meeting.  Information on the status
         of environmental efforts at EAFB was provided at the open house.

     •   Newspaper articles. Articles have been written for the base newspaper regarding ERP
         activity.

     •    Proposed Plan. The proposed plan on this action was distributed to the mailing list
         addressees for their comments.
A public  comment period was held from December 28, 1995 to January 27, 1996, and a public
meeting was held on January 11, 1996. At this meeting, representatives from EAFB answered
questions about the remedial action. A response to the comments received during this period is
included in the Responsiveness Summary, which is part of this Record of Decision (ROD).

This ROD is based on the contents of the Administrative Record for OU-12, in accordance with
the CERCLA, as amended by SARA, and the NCP. The RI/FS reports and the Proposed Plan for
OU-12 provide information about OU-12 and the selected remedy. These documents are available
at the Information Repositories at EAFB and the Rapid City Public Library.
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                                                      Final Record of Decision Operable Unit 12
                                                        Ellsworth Air Force Base, South Dakota
 2.4 SCOPE AND ROLE OF RESPONSE ACTION

 The FFA identified 11 site-specific area operable units (OUs) as well as a Base-wide
 ground-water operable unit. The 12 operable units are identified as follows:

         OU-1        Fire Protection Training Area
         OU-2        Landfills Nos. 1 and 6
         OU-3        Landfill No. 2
         OU-4        Landfill No. 3
         OU-5        Landfill No. 4
         OU-6        Landfill No. 5
         OU-7        Weapons Storage Area
         OU-8        Explosive Ordnance Disposal Area (Pramitol Spill)
         OU-9        Old Auto Hobby Shop Area
         OU-10      North Hangar Complex
         OU-11      Base-wide Ground Water
         OU-12      Hardfill No. 1

 This ROD is to  document the selected remedy for the preferred remedial action (RA) at OU-12
 and is the ninth  ROD for EAFB.  The remedial action objectives (RAOs) are to reduce the
 potential risks posed by contaminants in surface soils and to reduce the mobility of potential
 contaminants in the hardfill through containment.

 The development of alternatives for OU-12 was conducted under EPA's Presumptive Remedies
 Approach [Presumptive Remedies: Policy and Procedures (OSWER Directive 9355.0-47FS);
 Presumptive Remedy for CERCLA Municipal Landfill Sites (OSWER Directive 9355.0-49FS);.
 By using this approach, selection of an alternative for remediation is streamlined by using
 preferred technologies based on historical patterns of remedy selection and EPA's scientific and
 engineering evaluation of performance data on technology implementation.

 The presumptive remedy  stipulates containment as the appropriate remedy for landfills. The
 response action, containment by capping, would remove risk associated with the ingestion, dermal
 contact, and inhalation exposure pathways. The area of attainment defines the area over which
 preliminary remediation goals would be achieved, and is based on the RAOs. The area of
 attainment would include hardfill areas not meeting appropriate closure standards. The remedy
 does not address leachate remediation since identified wastes placed in the hardfill do not typify
 that which would normally be associated with leachate production. Ground-water monitoring will
 identify whether leachate is being produced in the future.

 2.5 SITE CHARACTERISTICS

 This section describes the presence and distribution of contaminants at OU-12 as a result of past
 activities.

 2.5.1    Soils
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                                                      Final Record of Decision Operable Unit 12
                                                         Ellsworth Air Force Base. South Dakota
     Volatile Organic Compounds (VOCs)

 Five different VOCs were reported in the 1995 RI surface and subsurface soil samples from
 OU-12.  The maximum reported value was 47 micrograms per kilogram (ug/kg) of toluene in a
 sample collected from the southern edge of OU-12.

     Jet Fuel

 Total petroleum hydrocarbons (TPH) as jet fuel was reported in 9 of 18 surface soil samples at a
 maximum concentration of 2,500 milligrams per kilogram (mg/kg). Jet fuel was reported in
 surface soil samples collected from both within and outside the identified hardfill areas.  Jet fuel
 was not reported in capillary fringe samples, but was reported in three other subsurface samples at
 a maximum concentration of 260 ug/kg.

     Semi-Volatile Organic Compounds (SVOCs)

 Twenty-three separate SVOCs were reported in surface soil samples collected during the RI at
 OU-12. The majority of the SVOCs was fuel related polycyclic aromatic hydrocarbon
 compounds (PAHs). Many of the reported SVOCs are considered to be related to Basewide
 activities associated with aircraft operations and not with disposal practices at the hardfill.  The
 highest concentrations of surface-soil SVOCs were, however, reported in soil samples collected
 from near the soil piles and fill areas.

     Pesticides

 Two pesticides were reported in surface soil samples and two pesticides were reported in
 subsurface  soil samples from OU-12.  The maximum reported pesticide concentration was
 33 ug/kg of p,p'-DDD in a surface soil sample.  The reported concentrations are typical of urban
 and agricultural areas and are considered to be the result of past pest-management practices at
 EAFB.
    Inorganic Constituents

Analytical results of surface soil samples indicated that the highest number of inorganic
constituents above background were reported in a sample collected west of the soil piles. The
largest number of these inorganic constituents was found in samples collected in the central-
eastern portion of OU-12.  The mean concentrations of some inorganic constituents in subsurface
soil samples are 240 mg/kg for barium, 18.3 mg/kg for lead, 1563 mg/kg for manganese, and 21
mg/kg for arsenic. There appears to be no pattern in the distribution of the reported inorganic
constituents.  The random distribution suggests the natural occurrence of these compounds in the
soil. However, these inorganic constituents were still evaluated in the risk assessment due to the
uncertainty associated with the disposal practices.

2.5.2    Sediment
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                                                       Final Record of Decision Operable Unit 12
                                                         Ellsworth Air Force Base, South Dakota
     Organic Contaminants

 Acetone was reported in one sediment sample at a concentration of 430 ug/kg, and carbon
 disulfide was reported in two samples at a maximum concentration of 35 ng/kg. Total petroleum
 hydrocarbons was reported in each of the seven sediment samples, at a maximum concentration
 of 20,000 ug/kg. Twenty-two SVOCs were reported in the OU-12 sediment samples, including
 PAHs, carbazole, 4-methylphenol, dibenzofuran, and phthalates. The highest reported SVOC
 concentrations were reported in the upgradient sample. The exact source of SVOCs in the
 sediment is not known, but impacts  from upstream of OU-12 are considered likely.  Pesticides
 were reported in each of the sediment samples. No discernible pattern was observed, and the
 source of the reported pesticides is considered to be Basewide pest management practices.

     Inorganic  Contaminants

 Nineteen of the twenty inorganics analyzed for were reported in the six sediment samples from
 OU-12. The mean concentrations of some inorganic compounds detected in sediment samples are
 384 mg/kg for barium, 149 mg/kg for lead, 685 mg/kg for manganese, and 15.4 mg/kg for
 arsenic. There does not appear to be any pattern to the distribution of the reported inorganic
 contaminants.

 2.5.3   Ground Water

 Ground-water sample results do not indicate any discernable ground-water contamination at
 OU-12. Low levels of certain contaminants were intermittently detected in ground-water samples
 from isolated areas.

     Organic Contaminants

 Acetone was reported in three often ground-water samples at concentrations ranging from
 11 micrograms per liter (ug/L) to 17 ug/L. Trichloroethene (TCE) was reported in two often
 samples at a maximum concentration of 7.0 ug/L.  Total-1,2-dichloroethene (DCE) was reported
 in one sample at a concentration of 19.0  ug/L, and 1,1,1-trichloroethane (TCA) was reported in
 one sample at an estimated value below the sample quantitation limit (SQL) of 0.40 ug/L. Two
 SVOCs (naphthalene and bis (2-ethylhexyl)phthalate) were reported in OU-12 ground-water
 samples.  Five different pesticides were reported in the OU-12 ground-water samples.  With the
 exception of one sample collected east of a hardfill area on the southern end of the OU, reported
 pesticides are associated with samples from wells located upgradient of OU-12 hardfill areas.

    Inorganic Contaminants

 Twelve inorganic constituents were reported at concentrations greater than the background range.
 Nickel and Antimony were the only  inorganic constituents reported above the Safe Drinking
 Water Act Maximum Contaminant Level (MCL) of 100 ug/L and 6 ug/L, respectively.   The
 inorganic constituents detected in ground water are considered to be the result of natural
 variations in geologic deposits because they were reported at levels consistent with background.

 2.5.4   Surface Water

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                                                      Final Record of Decision Operable Unit 12
                                                        Ellsworth Air Force Base, South Dakota
     Organic Contaminants

 Four VOCs, benzene, ethylbenzene, toluene, and xylene, were reported in surface water samples
 from OU-12. The exact source of the reported VOC is not known, but reported values are
 indicative of non-point source runoff from the industrial portion of the Base, taxiways, and aprons
 upstream of OU-12.  Total petroleum hydrocarbons as jet fuel was reported in two of the six
 surface water samples at a maximum concentration of 180 ug/L.  These two surface water
 samples were taken from locations further upstream than the other four surface water samples.
 The jet fuel in surface water samples is considered to be a result of discharge from the Base
 operation area upstream of OU-12.  Eight SVOCs and one tentatively identified compound (TIC)
 were reported in surface water samples. The source of reported SVOCs is considered to be
 runoff from Base operations areas north of OU-12. One pesticide was reported in each of the
 three samples which were taken upstream from the hardfill areas.  Reported concentrations are
 consistent with what would be expected with past pest-management practices at EAFB.

    Inorganic Contaminants

 Three analytes, arsenic,  iron, and manganese, were reported at concentrations exceeding Federal
 Ambient Water Quality  Criteria (FAWQC). The source of the reported inorganics in surface
 water is considered to be from a combination of naturally-occurring geologic deposits and Base
 operation areas upstream of OU-12.
 2.6 SITE RISK SUMMARY

    Human Health Risks

    Risk Assessment Process .

 The assessment of human health risks for this OU considered the following topics:

 (1) Contaminants of concern (COCs) in ground-water, surface water, sediment, and soil samples
    taken at OU-12;

 (2) Current and future land-use conditions;

 (3) Potential environmental pathways by which populations might be exposed;

 (4) Estimated exposure point concentrations of COCs;

 (5) Estimated intake levels of the COCs;

 (6) Toxicity of the COCs; and

 (7) Uncertainties in the assessments of exposure, toxicity, and general risks.

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                                                         Final Record of Decision Operable Unit 12
                                                           Ellsworth Air Force Base, South Dakota
 Noncarcinogenic and carcinogenic risks were calculated for the following five potential exposure
 groups:

 (1) Current EAFB maintenance personnel mowing grass on-site;

 (2) The future child/adult living on-site who ingests or has dermal contact with surface soil;

 (3) The future adult living on-site who ingests and showers with shallow ground water;

 (4) Future adolescents who are exposed to surface water and sediment through wading; and,

 (5) Future adult construction workers who excavate on-site for building residences.

 A quantitative risk assessment was performed for the ground water, soil,  sediment, and air.  The
 risk assessment evaluated potential effects on human health posed by exposure to contaminants
 within OU-12. Carcinogenic risks were  estimated as the incremental probability of an individual
 developing cancer over a lifetime as a result of exposure to a potential cancer-causing chemical.
 The acceptable risk range expressed as a probability is one cancer incident in ten-thousand people
 to one cancer incident in a million people. This level of risk is  also denoted by 1 x 10"4 to 1 x 10"*.
 Risks within the acceptable risk range may or may not warrant remedial action depending upon
 site-specific circumstances. Risks below this range cannot be differentiated from the background
 occurrence of cancer in human populations.
 Noncarcinogenic health risks  are evaluated using a hazard index (Ffl).  If the hazard  index is less
 than or equal to one, the contaminant concentration is considered an acceptable level and
 generally assumes that the human population may be exposed to it during a 30-year period
 without adverse health effects. Risks calculated in a risk assessment are potential risks and are
 excess (i.e., over background) risks due to exposure from contaminants at the OU.

     Risk Assessment Results

 The risk assessment for OU-12 indicated that the total carcinogenic site risk is within the
 acceptable risk range for the residential scenario and is less than 1X10"* for industrial scenario.
 The majority of the total carcinogenic site risk for the residential scenario  is from  exposure to
 surface soil contaminants from within the hardfill. The noncarcinogenic His are below the
 reasonable maximum exposures (RME) of 9 x 10"5 for current industrial land use and 1 x 10"1 for
 future residential land use. The  average His for both current industrial land use and future
 residential land use were 3 x 10"6 and 5 x 10"2,  respectively. However, due to the heterogeneity of
 the hardfill contents, great uncertainty is  associated with the calculated risk values.

 Arsenic and benzo(a)pyrene in the sediment of the drainage areas also contributed to the total site
 risk. Based on the risk assessment (risk calculated for sediment is 3 x 10"6), and other factors
 such as maximum concentrations, distribution, detection frequency, etc., remediation is not
 warranted for sediment at OU-12.

 The risk to human health from the ingestion and use of the shallow ground water is 2 X 10"6.  This
 is on the lower end of the acceptable risk range.  Based on this  calculated  acceptable risk and low

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                                                        Final Record of Decision Operable Unit 12
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 concentrations of contaminants detected in ground-water samples, remediation is not warranted
 for ground water.

 The calculated risk level for the surface water at OU-12 is 8 X 10'8, which is below the acceptable
 risk range. Remediation is not warranted for surface water as part of OU-12.

     Risk Assessment Conclusions

 Remedial action is warranted for the hardfill based on the potential risk to human health from
 future releases of hazardous substances from the hardfill.  Contaminants in the hardfill may leach
 downward to contaminate the underlying ground water. Off-Base residents may then ingest or
 come in contact with the contaminated ground water.  Also, the surface of the hardfill may erode,
 thus exposing off-Base residents to contaminants in both surface water and air.

 Due to the potential heterogeneity of the waste materials present within the hardfill, a complete
 characterization of waste materials present was not possible during the RI.  This adds a degree of
 uncertainty to the risk assessment for the hardfill contents.

 Rather than attempting to fully characterize hardfill contents and gain more  certainty in the risk
 assessment, the Air Force utilized guidance developed by EPA titled Presumptive Remedy for
 CERCLA Municipal Landfill Sites (OSWER Directive 9355.0-49FS). The  presumptive remedy
 for landfills is containment (capping) of landfill contents. Using the presumptive remedy strategy,
 a quantitative risk assessment is not necessary to evaluate whether the containment  remedy
 addresses all  exposure pathways and contaminants potentially associated with a landfill.  Rather,
 all potential exposure pathways can be identified using the conceptual site model and compared to
 the pathways addressed by the presumptive remedy.  Containment of the landfill contents
 addresses exposure pathways and risks normally associated with landfills. The contaminant
 exposure pathways for the potential risks associated with the hardfill contents at OU-12 include
 (1) direct physical contact with the hardfill contents and (2) consumption or contact with ground
 water that may become contaminated, (3) consumption or contact with potentially contaminated
 surface water, and (4) ingestion of potentially contaminated sediment in the  drainage channel
 which bisects OU-12.

 Actual or threatened releases of hazardous substances from OU-12, if not addressed by
 implementing the response action selected in this Record of Decision (ROD), may present an
 imminent and substantial endangerment to public health, welfare, and the environment.

   . Ecological Risks

 An ecological risk evaluation of OU-12 was based on a combination of data and literature
 reviews, field and laboratory analyses, analyte evaluation and screening, and preliminary risk
 screening.  The ecological risk assessment was performed in three phases, or tiers. Tier I was a
 screening-level risk assessment.  Tiers II and III were progressively more detailed risk
 assessments.  The pertinent findings are summarized below.

 OU-12 presents a mixture of disturbed habitat, such as the exposed hardfill area and associated
 weedy vegetation, and attractive habitat including grassland, wetlands, and some cottonwood and

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                                                        Final Record of Decision Operable Unit 12
                                                          Ellsworth Air Force Base, South Dakota
 willow trees. In spite of the disturbance, including the close proximity of OU-12 to the runway, a
 variety of ecological receptors could be attracted to the area for foraging and possibly nesting.

 Rare, threatened, or endangered species could also utilize OU-12 for foraging and possibly
 nesting.  There were no rare, threatened or endangered animal or plant species identified at OU-
 12.  However, rare, threatened, or endangered species may utilize OU-12 as a transient habitat.

 Due to the low levels of contaminant concentrations, the contaminants do not pose an
 unacceptable risk to these species.  In addition, the limited contact these species would have with
 the OU-12 area ensures unacceptable risk to a single individual will not occur.

 Terrestrial vegetation and soil fauna communities differ between OU-12 and a reference area.
 Influence of chemicals detected in the soil could be neither confirmed or denied, based on the
 data. This prompted movement of the OU from Tier I to Tier II ecological evaluation.
 Findings of the OU-12 RI indicate that the contaminants at OU-12 are not affecting species
 identified in the vicinity of EAFB on a population basis. However, screening of chemical
 concentrations in surface water, sediment, and surface soil, and sample-by-sample examination of
 the database, identified a number of metals and organic compounds present at sufficient
 concentrations to warrant a Tier HI risk assessment.  The Tier III risk assessment will be a Base-
 wide ecological risk assessment to be conducted as part of OU-11.

 2.7    DESCRIPTION OF ALTERNATIVES

 Presumptive Remedy for CERCLA Municipal Landfill Sites, (OSWER Directive 9355.3-11FS)
 was the basis for the abbreviated feasibility study (FS). The OSWER directive established
 containment of the contamination within the landfill as the presumptive remedy for municipal
 landfills.

 Although not specifically identified as a municipal landfill, OU-12 exhibits characteristics that
 make this presumptive remedy applicable. The hardfill contents at OU-12 do not have the
 characteristics to produce any significant leachate or gas, although detectable levels of methane
 gas was identified in one area of OU-12. The risk assessment did not identify the ground water as
 a pathway of concern. Even though the hardfill contents were not identified  as a source of
 unacceptable risk to human health, the heterogeneity of the hardfill contents causes uncertainties
 in the risk assessment. Therefore, the presumptive remedy focuses on containment of the hardfill
 contents.

 • .    Alternative 1 - No Action

       •      The no-action alternative represents the baseline condition at OU-12 and refers to
             taking no action at OU-12,  although existing maintenance of the site (mowing)
             would be continued.

 •      Alternative 2 - Institutional Controls

       •      Institutional controls (access restrictions and deed restrictions).
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                                                       Final Record of Decision Operable Unit 12
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        •      Monitoring of ground water, and sediment.

        •      Long-term maintenance of existing soil cover.

 •      Alternative 3 - Capping

        •      Placing a soil cover capable of sustaining vegetation on the area of attainment at
              HardfillNo 1.

        •      Long-term maintenance of soil cover.

        •      Monitoring and institutional controls as stated in Alternative No. 2.
 2.8     SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES

 The analysis of alternatives coupled with the use of the presumptive remedy combine for a
 narrower range of feasible approaches to address remedial activities at OU-12.

 The remedial action objectives for OU-12 are as follows:

       Hardfill

       •      Prevent ingestion and dermal contact with hardfill contents.

       •      Reduce the mobility of potential contaminants in the hardfill.

       •      Control surface water runoff and erosion of the hardfill cover.

 The area of attainment is defined as the area which will achieve the remedial action objectives
 after remediation is completed.  The area of attainment for OU-12 is the extent of the hardfill
 areas, approximately 14 acres (Figure 2-5).

 Pursuant to Section 300.430(e)(9)(iii) of the EPA's revised NCP, the remedial action to be
 implemented should be selected based upon consideration of nine evaluation criteria.  These
 criteria are as follows:

       1.      Overall protection of human health and environment.
       2.      Compliance with applicable or relevant and appropriate requirements (ARARs).
       3.      Long-term effectiveness and permanence.
       4.      Reduction of toxicity, mobility, or volume  of contamination.
       5.      Short-term effectiveness.
       6.      Implementability.
       7.      Cost.
       8.      State acceptance.
       9.      Community acceptance.

 The following sections provide  a brief review and comparison of the remedial alternatives


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                                                        Final Record of Decision Operable Unit 12
                                                          Ellsworth Air Force Base, South Dakota
 according to EPA's evaluation criteria.

 2.8.1   Overall Protection of Human Health and the Environment

 The assessment of this criterion considers how the alternatives achieve and maintain protection of
 human health and the environment.

 Alternative 1 (no action) does nothing to reduce risk at OU-12.  Alternative 2 (institutional
 controls) provides for maintenance of non-vegetated areas. Access restrictions would reduce risk
 by reducing exposure. Alternative 3 (soil cover) provides containment of the hardfill contents.
 This would eliminate risk associated with exposure to potential contaminants in the landfill and
 the future risk associated with potentially contaminated ground water.

 2.8.2   Compliance with ARARs

 Alternatives are assessed under this criterion in terms of compliance with ARARs. Applicable
 requirements include cleanup standards, standards of control and other substantive environmental
 protection requirements,  criteria, or limitations promulgated under Federal or state laws that
 specifically address a hazardous substance, pollutant, contaminant, remedial action, location or
 other circumstances at a CERCLA site.

 Relevant and appropriate requirements address problems or situations sufficiently similar to those
 encountered at a CERCLA site that their use is well suited to the environmental and technical
 factors at a particular  site. The determination of "relevant and appropriate" emphasizes the
 similarity and appropriateness of the requirement to a site. ARARs are grouped into these three
 categories:

        •      Chemical-Specific ARARs are health or risk-based numerical values or
              methodologies which, when applied to site-specific conditions, result in
              establishment of the amount or concentration that may be found in, or discharged
              to, the  environment.

        •      Location-Specific ARARs restrict the concentration of hazardous substances or
              the conduct of activities solely because they are in specific locations such as flood
              plains, wetlands, historic places, and sensitive ecosystems or habitats.

        •      Action-Specific ARARs are usually technology or activity-based requirements or
              limitations on actions taken with respect to hazardous wastes.

 A summary evaluation of Federal and State ARARs pertinent to this remedial action is provided in
 Table 2-1 at the end of Section 2.0 and a narrative discussion of compliance with ARARs is
 provided below for the alternatives considered.

 Alternative 1 (No Action):

 The No Action alternative does not comply with State of South Dakota Solid Waste Management
 Regulations (ARSD Article 74:27). The OU-12 RI concluded that ground water has not been

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                                                        Final Record of Decision Operable Unit 12
                                                          Ellsworth Air Force Base, South Dakota
 adversely impacted and was not a potential transport pathway; therefore, ground water ARARs at
 the OU are met.  Alternative 1 does not meet the remedial action objectives for OU-12. An
 action would not be taken to prevent human contact with surface-soil contaminants and potential
 contaminants within the hardfill may leach to the ground water.
 Alternative 2 (Institutional Controls):

 Alternative 2 does not comply with State of South Dakota Solid Waste Management Regulations.
 The OU-12 RI concluded that ground water has not been adversely affected and was not a
 potential transport pathway; therefore, ground water ARARs at the OU are met.  Alternative 2
 does not meet the remedial action objectives for OU-12.

 Alternative 3 (Capping):

 Alternative 3 will meet State of South Dakota Solid Waste Management Regulations for the
 disposal of solid waste by providing containment of hardfill contents, access/development
 restrictions, and long-term monitoring. Additional cover material will be added under this
 alternative to achieve compliance with the State requirements. The State is Federally authorized
 for the Resource Conservation and Recovery Act (RCRA) Subtitle D Municipal Solid Waste
 Program (8 October 1993, 58 FR 52486).  The resulting cover will also ensure continued
 compliance with the Safe Drinking Water Act Maximum Contaminant Levels (MCLs) by
 preventing the downward transport of contaminants to the ground water.

 Section 404 of the Clean  Water Act (CWA) regulates the discharge of dredge or fill material into
 waters of the United States.  Section 404 is implemented through regulations set forth in 33 CFR
 parts 320 through 330 and 40 CFR Part 230. To fully cover the hardfill, the wetlands near the
 ephemeral stream may be filled.  This may  adversely affect a water of the United States.  The
 Executive Order on Protection of Wetlands (E.O. No. 11, 990)  requires Federal Agencies to
 avoid, to the extent possible, the adverse impacts associated with the destruction or loss of
 wetlands if a practical alternative exists. If the discharge of fill material into a water body cannot
 be avoided, the use of appropriate and practicable mitigation measures to minimize the adverse
 impact to the aquatic ecosystem will be required.  Appropriate mitigation measures may be
 implemented during the remedial action. If wetlands at OU-12 will be adversely effected, an
 alternate area will be chosen for construction of a new wetland for the mitigation purposes.  This
 ARAR will be met.

 Implementation of the presumptive remedy (containment by capping) strategy for landfills has
 been shown by EPA to meet the remedial action objectives by preventing direct contact with
 hardfill contents and ingestion of surface soil and sediment.

 2.8.3  Long-Term Effectiveness and Permanence

 The assessment of this criterion considered the long-term effectiveness of alternatives in
 maintaining protection of human health and the environment after response action objectives have

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                                                         Final Record of Decision Operable Unit 12
                                                           Ellsworth Air Force Base, South Dakota
 been met.

 Alternative 1 would not provide additional effectiveness or permanence in reducing the potential
 for direct contact or ingestion of the surface soil or sediments. No further controls for the OU
 would be developed under this alternative.

 Alternative 2 would provide for increased effectiveness of access restrictions (in addition to the
 general EAFB  access restrictions).  Additionally, maintaining vegetation on the hardfill would
 reduce erosion potential.  Permanency and reliability of these controls would be enhanced through
 long-term monitoring and maintenance of the OU. Uncertainties exist for the ability to provide
 long-term access restrictions.

 Alternative 3 would offer the highest level of long-term effectiveness.  The earthen cover would
 reduce potential future risks to human health. Erosion would be limited by the development and
 maintenance of a vegetated area.  Upon completion, long-term maintenance of the cover and
 monitoring of ground water would be provided. Future land uses will be allowed if the integrity
 of the hardfill cover is not compromised.

 2.8.4  Reduction of Toxicity, Mobility, and Volume Through Treatment

 The assessment of this criterion involves considering the anticipated performance of specific
 treatment technologies an alternative may employ.

 Alternative  1 would not provide for the reduction of toxicity, mobility, or volume of potential
 contaminants within the hardfill. Alternative 2 would reduce the mobility of contaminants in
 surface soils through long-term erosion maintenance of existing cover soils. Alternative 3 does
 not use treatment technologies, but reduces the mobility of potential contaminants in the hardfill
 through containment.

 2.8.5  Short-Term Effectiveness

 The assessment of this criterion considers the effectiveness of alternatives in maintaining
 protection of human health and the environment during the construction of a remedy until
 response action objectives have been met.

 It is not anticipated that the proposed alternatives would significantly impact worker or
 community health and safety during the implementation period. Alternatives 2 and 3 may impact
 community and worker health and safety through dust emissions during the initial construction
 phase. The impact could be minimized through dust mitigation.

 Alternatives 2 and 3 may create a short-term  increase in risk  during remedial activities due to the
 inhalation exposure  pathway. Disturbances of surface soil through earthwork and soil disturbance
 would result in exposure to workers. Dust mitigation during these activities would minimize this
 potential impact.  Alternative 3 would present the potential for temporarily increasing the
 opportunity for erosion of the disturbed soil,  although erosion and sediment control measures will
 help to minimize this adverse impact.
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                                                         Final Record of Decision Operable Unit 12
                                                           Ellsworth Air Force Base. South Dakota
 2.8.6   Implementability

 The assessment of this criterion considers the administrative and technical feasibility of
 implementing the alternatives and the availability of necessary goods and services for
 implementation of the response action.

 Alternative 1 would not be difficult to implement since, aside from long-term monitoring, no
 further action would be undertaken.

 Alternative 2 requires no special or unique activities and could be implemented using locally
 available materials and contractors. Long-term monitoring would indicate whether additional
 action would need to be implemented in the future.

 Alternative 3 could be implemented with standard construction equipment, materials, and
 methods. The availability of an on- or off-Base supply of cover material will require further
 consideration during the remedial design analysis.  Wetlands mitigation (as a result of drainage
 modifications) could also be implemented with standard construction equipment, materials, and
 methods. Land use (or deed) restrictions can be implemented at EAFB by various administrative
 means.

 2.8.7   Cost

 A summary of the costs for each alternative is presented on the following page.
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                                                                 Final Record of Decision Operable Unit 12
                                                                    Ell&vorth Air Force Base, South Dakota
Alternative No. 1 (No Action)
Total Capital Costs
Total Annual (Sampling/Analysis) Costs
30-Year Present Value for Annual Costs
Annual Cost = $0
Years = 30
Discount Rate = 5%
TOTAL 30-Year Present Value
$0
$0
$0
50
Alternative No. 2 (Institutional Controls)
Total Capital Costs
Total Annual (Sampling/ Analysis/O&M) Costs Years 1-5
Total Annual (Sampling/Analysis/O&M) Costs Years 6-30
30-Year Present Value for Annual Costs
Annual Cost Year 1-5 = $130,500
Annual Cost Year 6-30 = $66,700
Years = 30
Discount Rate = 5%
TOTAL 30-Year Present Value
$180,000
$130,500
$66,700
$1,301,500
51,481,500
Alternative No. 3 (Capping)
Total Capital Costs
Total Annual (Sampling/Analysis/O&M) Costs Years 1-5
Total Annual (Sampling/Analysis/O&M) Costs Years 6-30
30-Year Present Value for Annual Costs
Annual Cost Year 1-5 = $130,500
Annual Cost Year 6-30 = $66,700
, Years = 30
Discount Rate = 5%
TOTAL 30- Year Present Value
$1,497,500
$130,500
$66,700
$1,301,500
52,799,000
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                                                        Final Record of Decision Operable Unit 12
                                                          Ellsworth Air Force Base, South Dakota
 2.8.8  State Acceptance•• ——     	           -    - .—_.

 The assessment of this criterion considered the State's preferences for or concerns about the
 alternatives.

 The State concurs with the selected remedy. The State provided comments on the remedial
 investigation, feasibility study, Proposed Plan, and this ROD. After incorporating adequate
 responses to the comments into the respective documents, the State concurred with the remedy.

 2.8.9   Community Acceptance

 Comments offered by the public were used to assess the community acceptance of the proposed
 alternative.  The community expressed its concerns about the selected remedy during the public
 comment period. The questions and concerns of the community are discussed in detail in the
 Responsiveness Summary, which is Appendix B of this ROD.

 2.9     SELECTED ALTERNATIVE

 Based on the requirements of CERCLA, comparative analysis of the nine criteria, public
 comments, and in consultation with EPA and the State, the Air Force has determined that the
 selected alternative is Alternative 3, Capping. This alternative includes institutional controls in
 conjunction with physical modification of the OU to reduce potential risk. Five-year reviews of
 the remedy will be required because potential contaminants will remain at OU-12 following
 completion of remedial action. Major components of Alternative 3 are:

       •      Install an earth cover over the area of attainment at Hardfill No 1.

       •      Institutional controls to prevent future use of the area for residential use and/or
              limiting its use to industrial uses.

       •      Developing a long-term monitoring and maintenance plan for the hardfill.

 Each of these items is discussed below.

       Installation of Soil Cover

 An earthen cover over will be placed over Hardfill No. 1 (approximately 14 acres). Cover will be
 graded and contoured to maintain  stability and route surface-water runoff away from previously
 active fill areas and prevent ponding of the water. The cover will be vegetated to enhance
 evapotranspiration and reduce infiltration and soil erosion. A pre-design study will be conducted
 to examine the need for landfill gas control measures, and evaluate the need for erosion control
 measures along the stream adjacent to the hardfill areas.

 If the discharge of fill material into  a water body cannot be avoided, the use of appropriate and
 practicable mitigation measures to minimize the adverse impact to the aquatic ecosystem will be
 required.  Appropriate mitigation measures may be implemented during the remedial action. If
 lining or filling of the drainage channel results in  adverse impacts to wetlands at OU-12, an

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                                                         Final Record of Decision Operable Unit 12
                                                           Ellsworth Air Force Base, South Dakota
 alternate area will be chosen for construction of a new wetland for the mitigation purposes.

        Institutional Controls

 Institutional controls would be implemented to prevent human exposure to contaminated soil and
 ground water.  These controls will include: (1) issuing a continuing order by the Installation
 Commander to restrict access to the hardfill and to restrict or control temporary construction
 activities unless proper protective equipment is worn; (2) filing a notice with the State of South
 Dakota to recommend denial of water rights permit applications to install ground-water wells
 within the hardfill boundary and any area which may be affected by potential contaminants within
 the landfill; (3) filing a notice to the deed detailing the restrictions of the continuing order and
 ground-water well restrictions; and (4) a covenant to the deed in the event of property transfer.

 The continuing order would be issued by the Installation Commander to restrict access to or
 disturbance of the hardfill as long as Ellsworth AFB owns the property. Specifically, it would:

    •  Restrict or place limitations on the installation of any new underground utilities or other
       construction activities in the area of the hardfill, thus preventing accidental exposures to
       construction workers.

    •  Provide for the use of proper protective equipment, in the event that access through the
       hardfill cover is required.

    •  Require that  the integrity of the hardfill cover be maintained.  Limit future land uses to
       non-intrusive activities only.  Maintenance of the hardfill will require development of
       standard operating procedures (SOPs) to provide for inspections and repairs.  To assist
       with the institutional controls, a fence may be placed around the hardfill and authorized
       personnel would have access through a locked gate.  Access would only be allowed to
       perform hardfill monitoring and maintenance activities. Warning signs would be posted at
       the hardfill to deter unauthorized access.

 The continuing order also would mandate that, if the hardfill cover was ever removed or
 breached, the area of attainment would be re-evaluated to determine the need for a replacement
 cap or other remedial action.

 Continuing order requirements will be in effect as long as the property is owned by
 Ellsworth AFB.  In the case of the sale or transfer of property within OU-12 by the United States
 to any other person or entity, the Air Force will place covenants in the deed, which will restrict
 access and prohibit disturbance  of contaminated soils or the remedial action without approval of
 the United States. These covenants will be in effect until removed upon agreement of the State of
 South Dakota, the U.S. Environmental Protection Agency, and the U.S. Air Force or their
 successors in interest. The Air Force will also include in the deed the covenants required by
 section 120(h)(3) of the Comprehensive Environmental Response, Compensation and Liability
 Act (CERCLA), which include (1) a warranty that the United States will conduct any remedial
 action found to be required by law after the date of the transfer; (2) a right of access in behalf of
EPA and the Air Force or their successors in interest to the property to participate in any
 response or corrective action that  might be required after the date of transfer. The right of access

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                                                       Final Record of Decision Operable Unit 12
                                                          Ellsworth Air Force Base, South Dakota
 referenced in the preceding sentence shall include the State of South Dakota for purposes of
 conducting or. participating in any response or corrective action that might be required after the
 date of transfer.

    Long-Term Monitoring and Maintenance

 A maintenance program would be established to ensure the long-term integrity hardfill conditions
 remedy would be maintained. The maintenance program would include development of standard
 operating procedures (SOPs) to provide for inspections, repairs, and general maintenance of the
 hardfill.

 A long-term monitoring program will be developed and implemented during remedial action and
 is subject to approval of both EPA and SDDENR. Contaminant concentrations in the sediment
 and ground water will be monitored to evaluate the effectiveness of the hardfill cover and to
 determine if ground-water contaminants have been transported beyond the hardfill boundaries.

 This alternative will meet the remedial action objectives and reduce the potential risk for OU-12
 by reducing the mobility of potential contaminants in the hardfill. This will be achieved by the
 construction of the hardfill cover and maintenance and possible modification of drainage channel.

 This alternative meets the statutory requirements of Section 121 of CERCLA as amended by
 SARA. These statutory requirements include protectiveness of human health and the environment,
 compliance with ARARs, cost effectiveness, and use of permanent solutions and alternative
 treatment technologies to the extent practicable.

 The statutory preference for treatment is not satisfied; however, the selected alternative is the
 presumptive remedy (containment) developed by EPA for landfills.

 Alternative 3 would limit exposure of hardfill materials, and contaminants present in surface soils
 and sediment at the OU, to humans, wildlife and the environment. Therefore the selected
 alternative will be protective of human health and the environment and will comply with ARARs.

 2.10   STATUTORY DETERMINATIONS

 The selected remedy meets the statutory requirements of CERCLA as amended by SARA. These
 requirements include protection of human health and the environment, compliance with ARARs,
 cost effectiveness, utilization of permanent solutions and alternative treatment technologies to the
 extent practicable. Containment, by definition, does not attempt to reduce the toxicity or volume
 of potentially hazardous materials; rather, it reduces the likelihood of exposure to these materials
 by preventing the movement of materials beyond the boundaries of the hardfill and preventing
 direct contact with hardfill materials. The selected remedy represents the best balance of tradeoffs
 among the alternatives considered, with respect to pertinent criteria, given the scope of the action.

 The manner in which the selected remedy meets each of these requirements is discussed in the
 sections below.

 2.10.1  Protection of Human Health and the Environment

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                                                        Final Record of Decision Operable Unit 12
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 The selected remedy addresses health and environmental issues that were identified in the OU-12
 RI report. Specifically, the capping alternative:

     •   Eliminates exposure to hardfill contents by installing an earthen cap.

     •   Reduces the potential infiltration of contaminants to the ground water.

     •   Prevents unauthorized access to the area by installing a perimeter fence and restricted
        access signs.

     •   Provides for long-term monitoring of ground water and sediment to identify potential
        future risks associated with OU-12.

 2.10.2 Compliance with ARARs

 Alternative 3 will meet State landfill closure requirements by providing containment of hardfill
 contents, access/development restrictions and long-term monitoring. The OU-12 RI concluded
 that ground water has not been adversely affected and was not a potential transport pathway;
 therefore ground water ARARs at the OU are met.  Wetlands adversely affected by the remedial
 activities may need to be mitigated.  Additional information about ARAR compliance is contained
 in Section 2.8.2.

 Implementation of the presumptive remedy (containment by capping) strategy for landfills has
 been shown by EPA to meet the remedial action objectives by preventing direct contact with
 landfill contents.
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                                                        Final Record of Decision Operable Unit 12
                                                         ' Etlsivorth Air Force Base, South Dakota
 2.10.3 Cost Effectiveness

 The selected remedy provides overall effectiveness in reducing human health risks relative to its
 costs. The presumptive remedy process insures cost-effective remedies are chosen. The chosen
 hardfill cover type ensures containment of the hardfill contents. Site specific conditions were used
 to determine the type of cover necessary for the hardfill. Based on the information provided
 during the remedial investigation, a more costly cover would not be cost effective.

 2.10.4 Utilization of Permanent Solutions and Alternative Treatment Technologies to  the
        Extent Possible

 EPA has established that proper capping has proven effective in containing landfill contents.  This
 alternative provides long-term prevention of exposure to potential hardfill material, prevents
 unauthorized access, and provides for long-term ground water monitoring to detect movement of
 chemicals from the area. A five-year review of the selected remedy will be performed because
 contaminants may be remaining  within the hardfill. The review will be conducted no less often
 than every five years after  the signing of the ROD to ensure the remedy continues to provide
 adequate protection of human health and the environment.

 2.10.5 Preference for Treatment as a Principal Element

 Treatment of the hardfill contents is not supported based on the findings of the remedial
 investigation for OU-12. No identifiable hot spots were reported present and the risks associated
 with OU-12 can be addressed by eliminating  exposure to the hardfill contents by capping.

 2.11  DOCUMENTATION OF SIGNIFICANT CHANGES

 The selected action is the same as the preferred alternative presented in the Proposed Plan for
 OU-12 remedial action. There have been no changes relative to the Proposed Plan.
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                                                          Final Record of Decision Operable Unit 12
                                                             Ellsworth Air Force Base, South Dakota
TABLE 2-1   EVALUATION OF FEDERAL AND STATE ARARS THAT APPLY TO OU-12, ELLSWORTH AFB, SOUTH DAKOTA

Applicable or Relevant and Appropriate Federal Standards, Requirements, Criteria and Limitations
Standard, Requirement, Criteria
or Limitation
Safe Drinking Water Act
National Primary Drinking
Water Standards
National Secondary Drinking
Water Standards
Maximum Contaminant
Level Goals
Clean Water Act
Water Quality Criteria
Criteria and Standards for
the National Pollutant
Discharge Elimination
System
Citations
42 USC 300, f, g
40CFRPart 141.60-
.63
40CFRPart 143.3
40CFR 14 1.50 and
Public Law No. 99-
330, 100 Slat. 642
(1986)
33 USC 1251-1376
40 CFR Part 131.36
40CFRPart 125.1-.3
Description

Establishes health based standards for
public water systems (maximum
contaminant levels).
Establishes aesthetic based standards
for public water systems (maximum
contaminant levels).
Establishes drinking water quality
goals set at concentrations of
unknown or anticipated adverse
health effects with an adequate
margin of safety.

Establishes criteria for water quality
based on toxicity to aquatic organisms
and human health.
Establishes criteria and standards for
technology-based requirements in
permits under the Clean Water Act.
ARARType

Chemical
Chemical
Chemical

Chemical
Chemical
Applicability to OU-12

Relevant and appropriate for
federal Class II aquifers.
Relevant and appropriate.
Relevant and appropriate.

Relevant and appropriate.
Aquifer may be a federal
Class II A (discharge to
surface water).
Relevant and appropriate.
 R-\1>ROJ\6037885\I?S\ROD12\I-'1NAL\12I-'NLROD.W1'D
2-22
April. 19V6

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                                                                Final Record of Decision Operable Unit 12
                                                                  Ellsworth Air Force Base. South Dakota
TABLE 2-1    EVALUATION OF FEDERAL AND STATE ARARS THAT APPLY TO OU-12, ELLSWORTH AFB, SOUTH DAKOTA
               (Continued)
      Standard, Requirement, Criteria
              or Limitation
      Citations
           Description
  ARARType
   Applicability to OU-12
         Executive Order on
         Protection of Wetlands
      Clean Air Act
             National Primary and
             Secondary Ambient Air
             Quality Standards

             National Emission
             Standards for Hazardous
             Air Pollutants
E. O. No. 11,990
40 CFR 6.302(a) &
Appendix A
40 CFR Part 50.1-.6,
.8, .9,. 11,. 12
40 CFR Part 61
Requires federal agencies to avoid, to
the extent possible, the adverse
impacts associated with the
destruction or loss of wetlands and to
avoid support of new construction in
wetlands if a practicable alternative
exists.
Establishes standard for ambient air
quality to protect public health and
welfare.

Establishes regulatory standard for
specific air pollutants.
Action/Location
Applicable.  OU-12 has •
wetland areas adjacent to
remediation areas.
Action
Action
Applicable. Methane
treatment may be required at
OU-12.

Applicable. Methane
treatment may be required at
OU-12.
 F:\PROJ\6037885\FS\ROD12\I-'1NAL\12FNLKOD.WI'D
                                2-23
                               April, 1996

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                                                        Final Record of Decision Operable Unit 12
                                                          Ellsworth A ir Force Base, South Dakota
TABLE 2-1   EVALUATION OF FEDERAL AND STATE ARARS THAT APPLY TO OU-12, ELLSWORTH AFB,
             SOUTH DAKOTA (Continued)

Applicable or Relevant and Appropriate State Standards, Requirements, Criteria and Limitations
Standard, Requirement, Criteria
or Limitation
South Dakota Waste
Management Regulations
South Dakota Waste
Management Regulations
South Dakota Waste
Management Regulations
South Dakota Water Quality
Standards
South Dakota Ground Water
Standards
South Dakota Surface Water
Quality Standards
South Dakota Remediation
Criteria for Petroleum-
Contaminated Soils
Citations
74:26:03:04
74:27:03:11
74:27:15
74:03:04:02, 10
74:03:15
74:03:02
74:03:32
Description
Establishes requirements for disposal
of hazardous wastes in sanitary
landfills.
Defines requirements for closure of
solid waste disposal facilities.
Establishes standards for landfill
closure and post-closure monitoring.
Defines use of Box Elder Creek and
certain tributaries.
Defines ground water classifications
by beneficial use and sets chemical
standards.
Establishes surface water quality
standards.
Establishes requirements for the
remediation of soil contaminated with
petroleum products.
ARARType
Action
Action
Action
Action
Chemical
Chemical
Chemical
Applicability to OU-12
Relevant and appropriate.
Relevant and appropriate.
Relevant and appropriate.
Landfill closure imminent for
OU-12.
Relevant and appropriate.
Relevant and appropriate.
Relevant and appropriate.
Surface water exists at OU-12.
Relevant and appropriate.
 F: \1>ROJ\603 7885\I?S\ROD 12WNMM 2FNLHOD. \VPD
2-24
                                                                               April. 1996

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                                                     Final Record of Decision Operable Unit 12
                                                       Ells\vorth Air Force Base, South Dakota
                  3.0 LIST OF ACRONYMS AND ABBREVIATIONS

 ACC:        Air Combat Command
 AF:          Air Force
 AFB:         Air Force Base
 ARARs:      Applicable or Relevant and Appropriate Requirements
 CERCLA:     Comprehensive Environmental Response, Compensation and Liability Act
 COC:        Chemicals of Concern
 DNAPL:      Dense non-aqueous phase liquid
 EAFB: Ellsworth Air Force Base
 EP:          Extraction Procedure, the EPA's standard laboratory procedure for leachate
              generation.
 EPA:         Environmental  Protection Agency
 FFA:         Federal Facilities Agreement
 FPTA: Fire Protection Training Area                                          .  .
 FT A:         Fire Training Area
 GPR:         Ground Penetrating Radar
 HQ:          Headquarters
 IN SITU:      In the original place
 IRIS:         Integrated Risk Information System
 IRP:          Installation Restoration Program
 JP-4:         Jet Propulsion Fuel Number Four; contains both kerosene and gasoline fractions.
 LNAPL:      Light Non-Aqueous Phase Liquid
 MCL:         Maximum Contaminant Levels
 mgd:         Million Gallons per Day
 jig/L:         Micrograms per liter
 mg/L:        Milligrams per liter
 MSL:        Mean  Sea Level
 NAPL: Non Aqueous Phase Liquid
 NCP:        National Oil and Hazardous Substances Contingency Plan
 NEPA: National Environmental Policy Act
 NPDES:     National Pollutant Discharge Elimination System
 NPDWR:     National Primary Drinking Water Regulations
 NPL:        National Priorities List
 OU:         Operable Unit
 O&G:        Symbols for oil  and grease
 PAH:        Polynuclear Aromatic Hydrocarbon
 PCB:        Polychlorinated Biphenyl; liquids used as a dielectrics in electrical equipment
F:\PROJ\6037885ttAOD12\FIXAL\12FNLROD.WPDJI\"                  April, 1996

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                                                      Final Record of Decision Operable Unit 12
                                                        Ellsworth Air Force Base, South Dakota
 PCE:        Perchloroethylene; liquids used in degreasing or paint removal.
 PL:          Public Law^
 ppm:        Parts per million by weight
 RAO:        Remedial Action Objective
 RCRA: Resource Conservation and Recovery Act
 RI/FS: Remedial Investigation/Feasibility Study
 ROD        Record of Decision
 SARA: Superfund Amendments and Reauthorization Act
 SACM:       Superfund Accelerated Cleanup Model
 SVOC: Semivolatile Organic Compound
 TCA:        1,1,1,-tetrachloroethane
 TCE:        Trichloroethylene
 TCL:        Target Compound List
 TCLP: Toxicity Characteristic Leaching Procedure
 IDS:        Total Dissolved Solids
 TOC:        Total Organic Carbon
 TSD:        Treatment, storage or disposal sites/methods
 USAF: United States Air Force
 U.S. EPA:    United States Environmental Protection Agency
 USD A:       United States Department of Agriculture
 USFWS:      Unites States Fish and Wildlife Service
 USGS: United States Geological Survey
 VES:         Vertical Electrical Sounding
 VOC:        Volatile Organic Compound
 WQC:        Water Quality Criteria
 WWTP:       Wastewater Treatment Plant
F:\PROJ\6037885\FS\ROD12\FINAL\12FNLROD.IVPD        3-2                                  April, 1996

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                                                           Final Record of Decision Operable Unit 12
                                                             Ellsworth Air Force Base, South Dakota
                                          APPENDIX A


                                            FIGURES
F:\PROJ\6037885\F&ROD12\FINAL\12FNLROD.WPD                                                 April. 1996

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D
O
2 O
                                                                                       UMNESOTA

                                                                       ELLSWORTH AFB
                       Rapid City
                                                      Scale In Ulln
                                                      APPROXIMATE
                EL-L.S WORTH
                AIR   FORCE  BASE
 ELLSWORTH AFB
RAPID OTY. SOUTH DAKOTA
              AREA LOCATION MAP
    ROJECT UGR
                 DESIGNED BY
                               DRAWN BY
                                   MRG
                                             CHECKED BY
      SCALE
       AS  SHOWN
DATE
  JUNE 94
PROJECT NO
  60378.85
                                                                                                    FIGURE:
2-1

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*
o
m
              1200   2400
      SCALE IN FEET



            LEGEND

          OPERABLE UNITS

OU-1    FIRE PROTECTION  TRAINING
          AREA (FT-01)
OU-2    LANDFILLS  1 4 6 (LF-02)
OU-3    LANDFILL 2    (LF-03)
OU-4    LANDFILL 3  (LF-04"
OU-5    LANDFILL 4  (LF-05
OU-6    LANDFILL 5  (LF-06'
OU-7    LOW LEVEL RADIATION WASTE BURIAL AREA  (RW-07)
OU-B    EXPLOSIVE  ORDNANCE DISPOSAL AREA tc  PRAMITOL SPILL
OU-9    OLD AUTO HOBBY SHOP AREA  (OT-15)
OU-10  NORTH HANGAR COMPLEX  (ST-19)
OU-11"  BASEWIDE  GROUND WATER
OU-12  HARDF1UL NO.  1
  2
o: <
OQ
                ELLSWORTH
                AIR  FORCE  BASE
                                                 ELLSWORTH AFB
                                               RAPID Cm. SOUTH DAKOTA
                                                       SITE LOCATION  MAP
     ROJECT MGR
            DESIGNED BY
DRAWN BY
    STAFF
CHECKED BY
SCALE
 AS SHOWN
                                                                       DATE
                                                                     MAY 95
PROJECT NO
  60378.85
                                                                    FIGURE:
                                                          2-2

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                                                                 \  PRIMARY
                                                                   \INSTRUMENT
                                                                     X   RUNWAY
                                                 uuire or
                                                 ou-u STUOT AREA
  V     \   <    ./pi
.-•\:  -  V    (f  R
                                                                       WATER UTIUTY
                                                                       SANfTARY SEWER  UTIUTY
                                                                       SURFACE DRAINAGE
                                                                       EXPOSED HARDFILL AREA
                                                                       HISTORICAL HARDFILL AREAS
                                                                       WITH VEGETATION COVER

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2
£
6°
Is
  ~
            600*
                                         800*
                                                        WETLAND SPECIES:
                                                         T - THREE-EDGE BULRUSH (Scirpus pungtra)
                                                         A - CORDGRASS (Spnrtira, pttAvnata.)
                                                        A - CATTAIL (mostly Typha. latiJUia)
                                                        O - SEDGE (Car** spp.)
                                                        D - SPIKERUSH  (EUocharis maenstachya)
                                                         • - GIANT BULRUSH (Scirpus validvs)
                                                         f - SANDBAR WILLOW (Salix uxigua)
                                                         D - COTTONWOOD (Populvs
                                                               - BASE BOUNDARY FENCE
NOTE:   Map represents general distribution
       of dominant wetland species
                                                                          r:\HORIZONS\NeW\Uuai-OU\vtCl -7-4 Owe
                ELLSWORTH
                AIR   FORCE:  BASE:
                                              ELLSWORTH AFB
                                               PROJECT LOCATION
                               1993  Rl
                       OU-2,  OU-1,  tc OU-12
                      WETLANDS VEGETATION MAP
    ROJKTUCR
                DESIGNED BT
                        DRAWN BY

                             DJS
                                          CHECKED BT
SCALE
 AS SHOWN
                                                                    DATE
                                                                      MAR  94
PROJECT NO
  60378.85
                                                                                        FIGURE
2-4

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                                                                                         PRIMARY
                                                                                         INSTRUMENT
                                                                                            RUNWAY
                                                                                            TOPOGRAPHIC ELEVATION ABOVE
                                                                                            MSL - CONTOUR INTERVAL-10'

                                                                                            VEGETATIVE SOIL COVER
                                                                                            HISTORICAL HARDFILL AREAS
                                                                                            WITH VEGETATION COVER
                                                                                            LOCATION  OF SOIL PILE
                                                  SCALE
 P
 Z 
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                                                       Final Record of Decision Operable Unit 12
                                                          Ellsworth Air Force Base, South Dakota
                                       APPENDIX B


                              RESPONSIVENESS SUMMARY
F:\PROJ\603788S\FS\ROD12\FINAL\12FNLROD.WPD           ~'                                  April, 1996

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                                                      Final Record of Decision Operable Unit 12
                                                        Ellsworth Air Force Base, South Dakota
                                 Responsiveness Summary
                         .Remedial Action at Operable Unit Twelve
                          Ellsworth Air Force Base, South Dakota
 1.     Overview
 The United States Air Force (USAF) established a public comment period from December 28, 1995
 to January 27, 1996 for interested parties to review and comment on remedial alternatives considered
 and described in the Proposed Plan for Operable Unit Twelve (OU-12). The Proposed Plan was
 prepared by the USAF in cooperation with the U.S. Environmental Protection Agency (USEPA) and
 the South Dakota Department of Environment and Natural Resources (SDDENR).

 The USAF also held a public meeting at 7:30 p.m. on January 11, 1996 in the 28th Bomb Wing
 Auditorium at Ellsworth Air Force Base (EAFB) to outline the proposed remedy to reduce risk and
 control potential hazards at the Operable Unit (OU).

 The Responsiveness Summary provides a summary of comments and questions received from the
 community at the public meeting and during the public comment period, as well as the USAF's
 responses to public comments.

 The Responsiveness Summary is organized into the following sections:

       •     Background on Community Involvement

       •     Summary of Comments and Questions Received During the Public Comment Period
             and USAF Responses

       •     Remedial Design/Remedial Action Concerns

 Based on the requirements of CERCLA, comparative analysis of the nine criteria, public comments,
 and in consultation with EPA and the State, the Air Force has determined that the selected alternative
 is Alternative 3, Capping. Major components of Alternative 3 are:

       •     Install an earth cover over the area of attainment at Hardfill No 1.

       •     Institutional controls to prevent future use of the area for residential use and/or
             limiting its use to industrial uses.

       •     Developing a long-term monitoring and maintenance plan for the hardfill.
F:\PROJ\6037885\FSWOD12\FINAL\12FNLROD.WPD        B-l                                 April. 1996

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                                                       Final Record of Decision Operable Unit 12
                                                         Ellsworth Air Force Base, South Dakota
 2.     Background on Community Involvement

 On August 30, 1990 EAFB was listed on the USEPA's National Priorities List (NPL).  A Federal
 Facilities Agreement (FFA) was signed in January 1992 by the Air Force, EPA and the State and
 went into effect on April 1, 1992.  The FFA establishes a procedural framework and schedule for
 developing, implementing, and monitoring appropriate response actions for EAFB.

 Community relations activities that have taken place at EAFB to date include:

        •     FFA process.  After preparation of the FFA by the USAF, EPA, and SDDENR, the
              document was published for comment. The FFA became effective April 1, 1992.

        •     Administrative Record.  An Administrative Record for information was established
              in Building 8203 at EAFB. The Administrative Record contains information used to
              support USAF decision-making. All the documents in the Administrative Record are
              available to the public.

        •     Information repositories. An Administrative Record outline is located at the Rapid
              City Library (public repository).

        •     Community Relations Plan (CRP).  The CRP was prepared and has been accepted
              by EPA and the State of South Dakota and is Currently being  carried out. An update
              to this plan will be prepared in 1996.

        •      Restoration Advisory Board (RAB). The RAB has been formed to facilitate public
              input in the cleanup and meets quarterly. In addition to USAF, EPA, and South
              Dakota oversight personnel, the RAB  includes community leaders and local
              representatives from the surrounding area.

        •      Mailing list. A mailing list of all interested parties  in the community is maintained by
              EAFB and updated regularly.

        •      Fact sheet.  A fact sheet describing the status of the IRP at EAFB was distributed to
              the mailing list addressees in 1992.

        •      Open house. An informational meeting on the status of the IRP and other
              environmental efforts at EAFB was held on May 6,  1993.  An open house was held
              November 16, 1995 in conjunction with the Restoration Advisory Board meeting.
              Information on the status of environmental efforts at EAFB was provided.

       •      Newspaper articles. Articles have been written for the base newspaper regarding IRP
              activity.
F:\PROJ\6037885\FSWOD12\FINAL\12FNLROD.WPD         J}-2                                  APnl- 1996

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                                                       Final Record of Decision Operable Unit 12
                                                          Ellsworth Air Force Base, South Dakota
 The Proposed Plan for this remedial action was distributed to the mailing list addressees for their
 comments and additional copies of the Proposed Plan were available at the January 11, 1996 public
 meeting.  A transcript of comments, questions and responses provided during the public meeting was
 prepared.  Base on these public meetings, there have been no key public issues with the exception of
 surface water runoff from OU-12.

 3.     Summary of Comments and Questions Received During the Public Comment Period
        and USAF Responses

              Part I - Summary and Response to Local Community Concerns

 Review of the written transcript of the public meeting did not indicate community objections to the
 proposed remedial action.  No written comments were received during the public comment period.

 The majority of the comments received during the public meeting were in the form  of questions about
 the remedial investigation findings, the remedial action; i.e., what would be done, how it would be
 done, and what effects the action might have.  Representatives of the USAF were available to
 provide answers to the questions and also provided an overview presentation during the meeting to
 describe the proposed actions.

              Part n - Comprehensive Response to Specific Technical, Legal and
              Miscellaneous Questions

 The comments and questions below are in the order they appear in the written transcript of the
 January 11, 1996 public  meeting.

 Comment 1.  Mayor Baldwin

       Asked about whether the cost for covering the landfill could be justified for a landfill that
       poses no unacceptable risk.

 Response:    The presumptive remedy was selected as the preferred alternative based on the
              uncertainty associated with the presence of hazardous substances within the hardfill.  It
              is not practical to determine the exact type and quatity of contaminants within the
              hardfill; the  cost of such an investigation would be prohibitive. Narrowing scope of
              investigation allowed the Air Force to save money up-front.  The soil cover is an
              economical type of cover which permits the Air Force to achieve a great degree of
              confidence that the public health and safety is being protected. The cover would also
              prevent future releases of unidentified contaminants from within the hardfill to the
              underlying ground water. If the ground water were to become contaminanted, a large
              amount of money would be needed for the ground-water remediation, similar to the
              money being spent for the ground-water cleanup at OU-4.
F:\PROJ\601788S\f-StfiOD12\FINAL\I2FNLROD.WPD         Jj-3                                   April, 1996

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                                                        Final Record of Decision Operable Unit 12
                                                          Ells\vorth Air Force Base, South Dakota
 Comment 2.  Jan Deming

        Asked about whether the results of the methane gas survey would change the preferred
        alternative fqr the site, and, if so, would any changes be brought before the public for
        comment.

 Response:    The results of the methane gas survey will be used to determine the extent of the area
               with methane, and the concentrations of methane in those areas.  The main concern
               with methane is that it.might hinder the growth of vegetation. The study will determine
               whether the level of methane is sufficient to warrant methane gas venting as part of the
               cover system.

 Comment 3.  Jan Deming

        Asked if the methane gas poses a health risk to humans.

 Response:   Methane is not a risk to humans at OU-12. Methane is the result of decomposition of
               organic material such as domestic refuse. All landfills that contain domestic refuse
              vent methane to the atmosphere, except in the case  of very, very large landfills.  The
              explosive nature of methane is generally the primary concern at landfills which would
              require a nonpermeable cover.  Since the cover at OU-12 will be made of perameable
              earthen materials, methane (if present) would not accumulate beneath the cover and
              present the explosive risk.

 Comment 4. Phyllis Engleman

        Asked if the drainage through the middle of OU-12 had any contaminants?

 Response:    Jet-fuel related contaminants were present in  the sediment. The contaminants were
              evaluated in the risk assessment. The calculated risk for the drainage channel is within
              the acceptable range.  The sediment is also being investigated as part of the Basewide
              Ecological Risk Evaluation under OU-11. If there is any need for remediation based
              on the findings of OU-11, it will be addressed in the OU-11 Proposed Plan.

 4.     Remedial Design/Remedial Action Concerns

 During the Remedial Design (RD), the Base will make available a fact sheet and a notice of
 availability of the Record of Decision to allow additional public involvement.
F:\PROJ\602788S'
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