PB99-963917
                             EPA541-R99-060
                             1999
EPA Superfund
      Record of Decision:
      Langley Air Force Base/
      NASA Langley Center OU 50
      Hampton, VA
      9/27/1999

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  RECORD OF DECISION
LANGLEY AIR FORCE BASE
    OPERABLE UNIT 50
      August 1999

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                              RECORD OF DECISION
                           LANGLEY AIR FORCE BASE
                           OPERABLE UNIT 50 (Sfte-61)

                                  DECLARATION

  SITE NAME AND LOCATION

  Langley Air Force Base
  Operable Unit 50 (Installation Restoration Program [IRP] Site 61)
  Hampton, Virginia

  STATEMENT OF BASIS AND PURPOSE

  This Record of Decision (ROD) presents the selected remedial action for IRP Site 6 1 designated
  Operable Unit (OU)-50, at Langley Air Force Base in Hampton,  Virginia (the "Site")' chSSfa
           ^IVan  omPre^s7 Enfonmental Response, Compensation, and lability Act
         m   A w ' "I"*??'   U'S'C- 9601 etseq- md> to the extent P«afcabto, the
 National Oil and Hazardous Substances Pollution Contingency Plan (NCP), 40 Code of Federal
 Regulations Part 300. This decision is based on the Administrative Record for this OU.

 The Virginia Department of Environmental Quality concurs with the selected remedy.

 DESCRIPTION OF THE SELECTED REMEDY

 OU-50 is part of a comprehensive environmental investigation and cleanup currently being
 performed at Langley AFB under the CERCLA program. This ROD addresses only OU-50- the
 other OUs located at Langiey AFB are being investigated separately under its installation   '
 restoration program and either have been or will be addressed in other RODs.  Also this ROD
 identifies the final action for soils and an interim action for ground water at the OU ' Ground
 water will be addressed in a final action on an installation-wide basis as a separate OU.

 This action addresses the principle threat at the OU by imposing land use restrictions that will
prevent any non-industrial activities from taking place at this location. In addition, the interim
ground water action will prevent any use, other than monitoring, of the ground water at the OU

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  The selected remedy is the implementation of institutional controls and monitoring and includes:

         1)     .Land use restrictions to prevent non-industrial use of the property, with the
               exception of the non-residential waterfront development plans as discussed in
               Section VT of this ROD and to maintain the integrity of the current asphalt
               parking lot;
        2)     Ground water use restrictions to prohibit use of the ground water for purposes
               other than monitoring;
        3)     Within 90 days of ROD signature, the Air Force shall produce a survey plat
               prepared by a professional land surveyor registered by the Commonwealth of
               Virginia indicating the location and dimensions of OU-50 and the extent of soil
               and ground water contamination;
        4)     The Air Force shall supply a copy of the plat and ensure the incorporation of
               these restrictions  into any real property documents necessary for transferring
               ownership from the United States, in the unlikely event that the United States
               sells or transfers the property. The real property  document would also include a
               discussion of the National Priorities List (NPL) status of this Site, as well as a
               description of the soil and ground water contamination.  The Air Force shall
               submit the survey plat to the City of Hampton recording authority for the limited
               purpose of providing public notice of the environmental conditions of and
               limitations on the use of the property.  No property right or interest is intended to
               be nor shall be created by such notice. In addition, the Air Force shall enter a
               note, in the local land recording office, to the real property document evidencing
               U.S. ownership of the property on which the OU is located that shall notify
               interested parties that the site was previously used to manage paint shop
               substances and waste;
       5)      Ground water monitoring to ensure contaminated ground water is not
               impacting the Back River. Specifics of the monitoring program will be
               developed by the Air Force, the United States Environmental Protection Agency
               and the Virginia Department of Environmental Quality and presented in a
              monitoring plan.

DECLARATION OF  STATUTORY DETERMINATIONS

The selected final remedy with regard to soils is protective of human health and the environment,
complies with Federal and state requirements that are legally applicable or relevant and
appropriate requirements (ARARs) to the remedial action and is cost-effective.  The soils
remedy utilizes permanent solutions and alternative treatment (or resource recovery) technology
to the extent practicable for OU-50.  With respect to groundwater contamination, the interim
measure is protective of human health and the environment and is cost-effective. Because this is
an interim measure, ARARs are waived and will be addressed under the final measures presented
in the future groundwater ROD.  This portion of the action is interim and is not intended to
utilize permanent solutions and alternative treatment (or resource recovery) technologies to the
maximum extent practicable. Because this portion of the action does not constitute a final

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 remedy for the ground water, the statutory preference for remedies that employ treatment that
 reduces toxicity, mobility or volume as a principal element will be addressed by the final ground
 water response.

 Because this remedy may result in hazardous substances remaining on-site above health-based
 levels, a review will be conducted within 5 years after commencement of the remedial action to
 ensure that the remedy continues to provide adequate protection of human health and the
 environment.

 This 5-year review will also include an evaluation of the status of the ground water remedy to
 determine if deed restrictions related to groundwater can be removed when ground water
 response actions are completed.
THOMAS J. KE£gy                                 Date
Lieutenant General, USAF
Vice Commander
ABRAHAM FERDAS                                 Date
Director
Hazardous Site Cleanup Division

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                               TABLE OF CONTENTS
 Section                                                                      page

 I.     Site Name, Location, and Description 	\

 H.    Site History	         2

 in.    Highlights of Community Participation	2

 IV.    Scope and Role of Operable Unit	4

 V.    Summary of Site Characteristics and Extent of Contamination	4

 VI.    Current and Potential Future Site and Resource Uses	7

 VII.   Summary of OU Risks	9

 Vffl.   Description of Alternatives	12

 EX.    Summary of Comparative Analysis of Alternatives	15

 X.     Selected Remedy	20

 XI.    Statutory Determinations	22

 XLI.    Significant Changes from Proposed Plan  	23

XHL   Responsiveness Summary	24

XIV.   References	27

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 APPENDIX A

 Table       Title


 1            Summary of Operable Units Under CERCLA Investigation

 2            Maximum Soil Concentrations Exceeding Industrial Screening Levels

 3            Maximum Groundwater Concentrations Exceeding Residential Tap
              Water Screening Levels

 APPENDIX B

 Figure       Title

 1            Location Map, Langley Air Force Base, Virginia

 2            Base Map of Langley AFB Showing the Location of the Site (SS-61)

 3            Soil and Ground Water Sampling Locations, Site 61 RI, Langley AFB

4            Waterfront Development Plan

APPENDIX C

Glossary

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  List of Acronyms
  AFB
  ARAR
  bgs
  CE
  CERCLA
  COPC
  °F
 DOD
 EEQ
 EPA
 GMF
 ffl
 IRP
 IT
 LUC
 LUCIP
 MOALUC
 msl
 MWR
 NCP
 NPL
 O&M
 OU
 PCB
 ppm
 RAGS
 RBC
 RI
 ROD
 RME
TMV
UST
  Air Force Base
  applicable, relevant and appropriate requirements
  below ground surface
  Civil Engineering
  Comprehensive Environmental Response, Compensation, and Liability Act
  chemical(s) of potential concern
 degrees Fahrenheit
 U.S. Department of Defense
 environmental effects quotient
 U.S. Environmental Protection Agency
 granular media filtration
 hazard index
 Installation Restoration Program
 IT Corporation
 Land Use Control
 Land Use Control Implementation Plan
 Memorandum of Agreement on Land Use Control
 mean sea level
 Morale, Welfare, and Recreation
 National Oil and Hazardous Substances Pollution Contingency Plan
 National Priorities List
 Operations and Maintenance
 Operable Unit
 polychlorinated biphenyl
 part(s) per million
 Risk Assessment Guidance for Superfund
 risk-based concentration
 remedial investigation
Record of Decision
Reasonable Maximum Exposure
toxicity, mobility and/or volume
Underground Storage Tank

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Versar       Versar, Inc.
VDEQ       Virginia Department of Environmental Quality

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                               RECORD OF DECISION

                            LANGLEY AIR FORCE BASE

                           OPERABLE UNIT 50 (Site-61)

                               DECISION SUMMARY
 '•      Site Name. Location, ?nd Descriptfoq

 Langley Air Force Base (LAFB) is an active U.S. Department of Defense (DOD) installation
 located approximately 180 miles south of Washington, DC, and is part of the Norfolk
 metropolitan area (Figure 1).  The Base sits on a peninsula bounded by the northwest and
 southwest branches of the Back River (Figure 2), which is a tributary of the Chesapeake Bay. In
 addition to the 3,152-acre Base installation, Langley AFB supports the 284-acre Bethel Manor
 Off-Base Housing Area.  Langley AFB was proposed to be included on the National Priorities
 List (NPL) in 1993 and finalized in 1994.  This list includes sites where uncontrolled hazardous
 substance releases may potentially  present serious threats to human health and the environment.
 Operable Unit 50 (OU-50) was one of the Installation Restoration Program (IRP) sites
 investigated under Comprehensive  Environmental Response, Compensation, and Liability Act
 (CERCLA) at Langley AFB and was initially designated IRP Site 61.

 OU-50 is located in the southeastern portion of LAFB and is situated on the Southwest Branch of
 the Back River.  As shown in Figure 3, the 2-acre OU is bordered by the Base Marina to the
 south, buildings to the west and northwest, staffi'marina parking to the north and northeast, and
 the Back River to the east. Current land use at OU-50 is categorized as industrial and is expected
 to remain industrial in the future.

OU-50 consists of two areas of concern:

•     The former Civil Engineering (CE) Paint Shop includes Building 615 and a fenced-in
      gravel area that had been used for the storage of paint thinner and paint, the mixing of
      paints, and the cleaning of painting equipment. The CE Paint Shop was in operation
      from the 1950's to early 1991. The OU is now occupied by Morale, Welfare and
      Recreation (MWR) for the administration of the Base Marina.

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  •      To the east of the CE Paint Shop is an area where a 2,000 underground storage tank
        (UST) was removed in 1993.  The UST contained unleaded gasoline and was used for
        fueling boats at the Base Marina.

  II.     Site History

  This section describes the history of OU-50 and regulatory activities conducted to date.
  A.     OU History

  OU-50 was originally identified in June 1992 when, during a discovery inspection for the
 Morale, Welfare, and Recreation (MWR) office, indications of soil contamination from paints
 and solvents was uncovered. An area that contained discharge residue from a water-jacketed
 paint spray booth was also discovered. Evidence of stained soil was visible at the OU. An UST
 at the marina adjacent to OU-50 leaked gasoline that was suspected to have spread into the area
 of the site. The UST and some of the surrounding soil was excavated in early 1993.

 During the removal of the marina UST, fill material was encountered, including creosote-treated
 pilings, paint containers, and other refuse.  Due to the discovery of this material, the OU was
 expanded to include buried waste as well as the UST. Analysis of ground water samples
 obtained from five monitoring wells installed during UST site characterization revealed the
 presence of petroleum hydrocarbons.

 B.     CERCLA Investigations

 Under CERCLA,  a remedial investigation (RI) was conducted from 1995 through 1998. This
 investigation was performed to characterize the  nature, magnitude and extent of contamination at
 OU-50, determine what risks to human health and the environment existed at OU-50, and
 determine if further action was necessary for OU-50. Results of the RI are discussed in section
 V(B).

 Ill-     Highlights of Community Participation

In accordance with Sections 113 and 117 of CERCLA, 42 U.S.C. Sections 9613 and 9617,
Langley AFB, in conjunction with the EPA and the Virginia Department of Environmental
Equality (VDEQ), issued a proposed plan on November 30, 1998, presenting the preferred
remedial alternative for OU-50. The Proposed Plan and supporting documentation were made

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   available for review at that time and are among the documents that comprise the CERCLA
   Administrative Record for the Site.


   The Administrative Record is available for review by the public at the following information
   repositories:


         •   Hampton Public Library
            4207 Victoria Boulevard
            Hampton, Virginia 23669
            (757)727-1154

         •  LangleyAFB
            Contact: Mr. Vern Bartels
            1CES/CEVR
            37 Sweeney Boulevard
            Building Number 328
            Langley AFB, Virginia 23665-2107
            (757)764-1046

 An announcement of an availability session, the comment period, and the availability of the
 Administrative Record for the remedy for OU-50 was published in the Daily Press, a newspaper
 of general circulation in Hampton, VA,  on November 29, 1998.


 The public comment period for the Proposed Plan was from November 30, 1998 to December
 29, 1998. A public availability session was held at the Virginia Air and Space Center in
 Hampton, Virginia on December 3, 1998 to inform the public of the remedial alternatives and to
 seek public comments.  At this meeting, representatives from EPA, VDEQ, and the Air Force
 were available to answer questions about conditions at the OU and the remedial alternative under
 consideration.  Responses to the comments received during this period are included in the
 Responsiveness Summary section of this Record of Decision (ROD).


 This ROD presents the selected remedial action for OU-50 determined in accordance with
 CERCLA, and to the extent practicable, the NCP. All documents considered or relied upon in
 reaching the remedy selection decision contained in this ROD are included in the  Administrative
Record for the Site and can be reviewed at the information repositories.

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  IV.     SCQPe and Rote of Operable Ugft

  Langley AFB was proposed to be included on the NPL in 1993 and finalized in 1994. The NPL
  includes Sites where uncontrolled hazardous substance releases may potentially present serious
  threats to human health and the environment. Discrete portions of an NPL site are often
  managed more effectively as Operable Units. OU-50 is one of the IRP OUs currently being
  investigated under CERCLA at Langley AFB. This ROD addresses OU-50, which is the IRP
  Site 61 soil and ground water.  The remaining OUs at Langley AFB are currently being
 independently investigated under CERCLA (Table 1).

 V.     Summary of OU Characteristics and Extent of Contamination

 Summarized below are the relevant findings of the work to date with regard to contaminated
 media (soil, ground water,  surface water and sediment) located within the boundaries of the OU.

 A.     OU Characteristics

 1.      Geology

 The OU lies within the Atlantic Coastal Plain physiographic province.  Ground surface at
 Langley AFB is predominantly flat lying, with most of the Base lying between 5 and 8 feet
 above mean sea level (msl). Drainage in the region is poor, with numerous saltwater and
 freshwater marshes located along the major streams flowing into the Chesapeake Bay. OU-50 is
 on the Southwest Branch of the Back River.

 The geology of the area around Langley AFB consists of a thin layer of topsoil overlying fill
 materials of varying thickness placed in developed areas and unconsolidated coastal plain
 sediments.1 Topsoil is primarily sandy, silty clays or silty, clayey sands deposited within the
 flood plains during periods  of higher sea level stands or deposited in an estuarine or lagoonal
 environment.  Fill material includes gravel, rubble, and construction debris, and is similar to
native materials. The coastal plain sediments were deposited when the area was a submerged
near-shore marine environment.

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  2.      Hydrogeology

  Three major ground water-bearing zones lie beneath Langley AFB. These include the Shallow
  Water Table Aquifer between 5 and 100 feet bgs, the Upper Artesian Aquifer between 100 and
  400 feet bgs, and the Principal Artesian Aquifer between 400 and 700 feet bgs. Recently
  measured ground water elevations at OU-50 ranged from 2.2 to 4.3 feet above msl. Even
  though the ground water in the vicinity of Langley AFB, including OU-50, is not used as a
  source of drinking water, individual homeowners have ground water wells that have been used
  for watering lawns and washing cars. However, the Shallow Water Table Aquifer provides an
  important source of drinking water farther to the west in King Williams, Charles City, New
  Kent, James City, and York Counties.  In Newport News and Hampton, there are areas where
  domestic ground water is obtained from wells that range from 50 to 100 feet in depth. These
 wells are probably completed in the Shallow Water Table Aquifer, which ranges from 5 to  100
 feet below land surface.2 Ground water in the shallow water table aquifer beneath the Base is not
 used as a source of drinking water due to high dissolved solids levels and low aquifer yield.
 Ground water flow in this aquifer is slow and flow direction is towards surface water bodies,
 including the Back River and its tributaries.

 3.      Meteorology

 Langley AFB has a modified continental-type climate with mild winters.1 During both winter
 and summer, temperatures are fairly moderate,-with winter temperatures ranging from 40 to 70
 degrees Fahrenheit (°F), and summer temperatures ranging from lows of 70°F to highs of mid-
 80s °F. Relative humidity varies between 67 and 76 percent, depending on the month.
 Prevailing wind direction is from the north during winter and from the south-southwest during
 the rest of the year. Precipitation ranges from 24 to 57 inches per year, and is evenly distributed
 throughout the year. Maximum precipitation is in July and August, with minimums in
 November and April.  Average seasonal snowfall in the area is less than 10 inches per year.

4.      Ecology

OU-50 lacks vegetation and is composed of structures, pavement, gravel and concrete slabs.

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 5.      Soils

 Soil at OU-50 has generally been paved with 90 percent of the ground surface covered by either
 asphalt or Building 615. OU-50 is known to be partially underlain by "made land", or fill
 materials of unknown origin.

 B.      Nature and Extent of Contamination

 In June of 1998 a Remedial Investigation (RI) was completed for OU-50.  The following is a
 summary of the RI.5

 Ground Water

 •       As a result of activities at OU-50, a plume of benzene in ground water is present.  The
        plume size is limited in lateral extent, has decreased in size over time, is centered at
        monitoring well SS61-MW2, and has not migrated beyond the boundaries of the OU.
 •       Arsenic levels exceed the USEPA Region HI tap water risk-based concentration (RBC).
        The highest concentrations of this inorganic chemical were observed in the northeastern
        portion of OU-50 (see Table 2, Appendix A).
 •       Other contaminants detected in ground water at OU-50 above USEPA tap water RBCs
        or pertinent regulatory levels include volatile organic compounds (acetone, carbon
        disulfide, chloroform, chloromethane, ethylbenzene and toluene); semi-volatile organic
        compounds (carbazole and naphthalene, the pesticide dieldrin, PCB-1260); and metals
        (barium, iron, manganese and thallium) (see Table 2, Appendix A).
Soils
       Benzo(a)pyrene, a semi-volatile organic compound, was detected in surface soils across
       OU-50. Concentrations in four samples exceeded USEPA's industrial RBC. The
       widespread presence of this compound may be attributed to the non-native materials and
       dredge spoils used to fill OU-50 (see Table 3, Appendix A).
       Arsenic was detected in 18 soil samples, 15 of which exceeded USEPA's industrial
       RBC. In general, concentrations increased east to west across OU-50, and
       concentrations were generally greater in the subsurface soils than in the surface soils
       (see Table 3, Appendix A).

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         PCB-1260 was detected in surface and subsurface soils in the eastern half of OU-50.
         Only the easternmost samples exceeded USEPA's industrial RBCs (see Table 3,
         Appendix A), The limited occurrence of PCB in soils may be related to the presence of
         non-native fill materials or the result of historical activities at adjacent OU-48 (Site OT-
         55).
  •       Lead was detected in all 18 soil samples collected, but only two exceeded USEPA's
         residential screening level (there is no current industrial screening level for lead) (see
         Table 3, Appendix A).

  Surface Water and Sediment

         Estimated surface water and sediment concentrations for those contaminants of concern
         detected in the ground water do not pose a risk to aquatic receptors.

 Contaminant Fate  and Transport

 OU-50 is located adjacent to the Base Marina, which represents an active potential source for
 contamination of sediments and surface water. Therefore, modeling techniques,  rather than
 sampling, were used to evaluate the potential impacts associated with the discharge of
 contaminated ground water from OU-50 to the Back River. Based on the results of the model
 results, no impacts to surface water/sediment are likely to be associated with ground water
 discharge from OU-50.

 VI.     Current and Potential Future OU and Resource Uses

 Current land use at OU-50 is classified as industrial and future land use is expected to remain
 industrial with the exception of incorporating the waterfront development plans. Details of the
 Waterfront Development Plans follow.

Waterfront Development Plans

A 10 year shoreline restoration plan has been created to guide the wetlands and shoreline
stabilization projects for a mile of shoreline on LAFB between the marina and the end of the
mile long building. For the area immediately to the east of the existing marina which includes

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 OU-50 (Figure 4), the design has called for the following:

 •       Shoreline Stabilization Improvements
         -  Recycling and resizing existing miss-sized hardscape materials
         -  Removal of unsuitable materials
         -  Proper installation of Filter Cloth
         -  Reshaping of shore and installation of Class I rip rap
         -  Planting of wetland fringe marsh

 •        Planting Riparian Forest Buffer
         - Native shrub  and tree plantings between shoreline stabilization and parking lot
         - Buffer acts as filtration feature

 •       Improvement of Pedestrian linkages along the waterfront
        -  Pedestrian pathway winds through the native plantings
        -  Paving will be pervious paver material or paver block material

 •       Improving Parking
        -  Resurface, restripe and efficiently align parking spaces as shown on the waterfront
        plans to accommodate additional parking spaces
        -  Area along the bulkhead at the gas pumps will remain covered with hardscape
        material to ensure the exposure pathway from the surface of the hardscape material to
        the soils beneath remains incomplete

•       Fish Cleaning Station
        - Existing station will be replaced with new fish cleaning equipment

There are currently no restrictions regarding use at OU-50, such as fences and signs.  Land
adjacent to OU-50 is currently industrial, recreational and commercial. Future adjacent land use
is expected to remain the same.

Ground water in the shallow water table aquifer at Langley AFB is not currently used as a source
of drinking water at or within Vi mile of the Base.3 Ground water near the coast is brackish to
saline, and therefore not potable.

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  VII.    Summar  of QU
  A risk assessment was conducted during the RI in accordance with the latest EPA policy on risk
  assessments.6  The results are summarized below.5

  A.      Human Health Risk Assessment

  The baseline risk assessment provides the basis for taking action and indicates the exposure
  pathways that need to be addressed by this remedial action. It serves as the baseline indicating
  what risks could exist if no action was taken at OU-50. This section of the ROD reports the
  results of the baseline risk assessment conducted for this OU.

 Health risks are based on a conservative estimate of the potential carcinogenic risk or the
 potential to cause other health effects not related to cancer. Carcinogenic risks and
 noncarcinogenic risks were evaluated. Three factors were considered:

        •  Nature and extent of contaminants at OU-50
        •  Pathways through which human and ecological receptors are or may be exposed to
           those contaminants at OU-50
        •  Potential toxic effects of those contaminants.

For this OU, the human  health risk assessment was based on exposure to soil under industrial
land use scenarios and exposure to groundwater under the potential future residential receptor as
a conservative estimate in the unlikely event that OU-50 might be developed for residential use.
The industrial land use was assumed to be exposure through construction activities limited to ten
days a year. Exposure would result from construction activities that require exposure to soils
beneath the current asphalt cover.  Surface water and sediment exposure as a result of marina
activities was considered in a qualitative manner.

Cancer risks are expressed as numbers reflecting the increased chance that a person will develop
cancer, if he/she is directly exposed (i.e., through working at the OU) to the contaminants found
in the ground water and  soil at the OU over a period of time.  For example, EPA's acceptable risk
range for Superfund OUs is 1  * 10"* to 1 * 10"*, meaning there is one additional chance in ten
thousand (1 * 10"4) to one additional chance in one million (1  * 10"6) that a person will develop

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  cancer if exposed to contaminants at a Superfund OU. The risk associated with developing other
  health effects is expressed as a hazard index (HI), which is the ratio of the existing level of
  exposure to contaminants at a OU to an acceptable level of exposure. Below an HI of 1, adverse
  effects are not expected.

  The human health risk assessment evaluated the results of:

  •       Direct contact with the contaminated soil
  •       Incidental ingestion of contaminated soil
  •       Inhalation of fugitive dust
 •       Ingestion of contaminated ground water
 •       Inhalation of vapor phase chemicals via ground water use
 •       Dermal contact with contaminated ground water

 Concentrations of chemicals detected in the soil, ground water, sediment and surface water
 during the focused RI were compared to risk-based screening levels and background levels. The
 chemicals of potential concern (COPC) identified in soil at OU-50 were metals (arsenic) and
 volatile and semi-volatile organic (benzo(a)pyrene) compounds and PCB-1260. COPCs
 identified in groundwater were acetone, arsenic, barium, benzene, carbazole, carbon disulfide,
 chloroform, chloromethane, dieldrin, ethylbenzene, iron, manganese, napthalene, PCB-1260,
 toluene and thallium.  The COPCs for soil and groundwater were then evaluated in the human
 health risk assessment. Estimated sediment and surface water concentrations were compared to
 RBCs.  No exceedences were identified, concluding that a risk assessment for exposure to these
 media was unnecessary.

 Health risk levels, determined using EPA guidance to ensure that conservative estimates of
 potential health effects are determined, differ depending on the assumed land use because human
 exposures differ with land use.  A conservative estimate of risk was developed incorporating the
 potential exposure pathways including direct skin contact with contaminated soil and ground
 water, accidental ingestion of soil and ground water, and inhalation of contaminated soil
particles and ground water. Plausible receptors that may be exposed to soil at the OU and which
were evaluated in the risk assessment included a construction worker, and future adult and child
resident (ground water only).
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 The lifetime cancer risk from exposure to contaminated soil for the construction worker at OU-
 50 is calculated as 4.3 x 1CT*. This lifetime risk is within the EPA's acceptable risk range of 1 x
 10"* to 1 x 10"4. The HI for the non-carcinogenic risk due to exposure to contaminated soil for
 the construction worker was estimated to be 0.012, which is below the target level of 1.0.

 For a theoretical future residential user, ground water use risk was determined to be 7 x 10"3,
 which exceeds EPA's acceptable risk range.  The calculated HI for the adult ground water
 consumer is  123 and for the child, 131, levels at which adverse health effects may occur.

 B.     Ecological Risk Assessment

 OU-50 lacks vegetation and is composed of structures, pavement, gravel and concrete slabs.  As
 a result, no complete exposure pathways for ecological receptors are associated with OU-50
 soils, and potential ecological risks associated with exposure to soil constituents were not
 quantified.

 The only potential exposure pathway to which ecological receptors could be exposed is the
 discharge of ground water to the Back River. Potential risks to ecological receptors were
 quantified for this pathway through the development of environmental effects quotients (EEQs).
 EEQs for ecological risk are similar to the hazard indices prepared for human health risk.  They
 are determined by dividing the site-specific concentrations by a conservative screening level.

 The results of the EEQ calculations indicated that none of the constituents for which surface
 water and sediment concentrations were estimated had calculated EEQs greater than  1.  These
 results indicate that estimated surface water and sediment concentrations in the Back River do
 not represent levels of concern from an ecological standpoint with respect to direct contact (i.e.,
 ingestion via gills and ingestion of sediment).

C.      Conclusions

The remedial objective for OU-50 is to protect human health and the environment.  Because the
current and anticipated future land use is non-residential, soils were evaluated only for
construction worker exposure. As indicated,  the risk posed to the construction worker is within
EPA's acceptable risk range; however, actual or threatened releases from hazardous substances

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  may present an imminent and substantial endangerment to public health or welfare under a non-
  industrial scenario. In addition, the risk from ground water to the theoretical resident exceeds
  EPA's acceptable risk range. Ecological risk assessment determined that there is minimal risk to
  terrestrial receptors at OU-50. The specific remedial objectives for this operable unit, therefore,
  are to assure that non-industrial use of the property, with the exception of the non-industrial
  waterfront development plans outlined in Section VI, and to prevent access to ground water
  other than for monitoring purposes.

  VIII.    Description of Alternatives

 The Feasibility Study for OU-50 presents five alternatives that address risks posed by
 contaminated ground water and soils. A summary of the remedial alternatives evaluated for OU-
 50 is presented below.

 Alternative 1- No Action

 The NCP requires that a "no action" alternative be considered to provide a baseline for
 comparison with action alternatives. Under this alternative,  no remedial action would be
 undertaken to address contaminated soil and ground water at OU-50.

 •      Capital Cost: $0
 •      Operations and maintenance (O&M) cost: $0
 •       Net present worth: $0

 Alternative 2 - Limited Action and Institutional Controls

This alternative includes institutional controls: land use restrictions to limit future uses of the OU
and require permits, qualified supervision, and health and safety precautions for activities
conducted on and near the OU. Because soils were evaluated for worker exposure (and not a
residential receptor), the use of this property would be restricted to industrial use under this
alternative. Ground water was not evaluated for construction worker exposure.  These
restrictions include: 1) land use restrictions to prevent non- industrial use of the property, with
the exception of the non-residential waterfront development  plans outlined in Section VI, and to
maintain the integrity of the current asphalt parking lot; 2) ground water use restrictions to

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  prohibit the use of ground water for purposes other than monitoring; 3) within 90 days of ROD
  signature, the Air Force shall produce a survey plat prepared by a professional land surveyor
  registered by the Commonwealth of Virginia indicating the location and dimensions of OU-50
  and the extent of soil and ground water contamination; and; 4) the Air Force shall incorporate
  these restrictions and supply a copy of the plat into any real property documents necessary for
  transferring ownership from the United States, in the unlikely event that the United States sells
  or transfers the property. The real property document would also include a discussion of the
  National Priorities List (NPL) status of this OU, as well as a description of the soil and ground
  water contamination.-  The Air Force shall submit the survey plat to the City of Hampton
  recording authority for the limited purpose of providing public notice of the environmental
  conditions of and limitations on the use of the property. No property right or interest is intended
  to be nor shall be created by such notice. In addition, the Air Force shall enter a note, in the
 local land recording office, to the real property document evidencing U.S. ownership of the
 property on which the OU is located that shall notify interested parties that the site was
 previously used to manage paint shop substances and waste.

 In addition, public awareness training would be developed and implemented to keep potentially
 affected individuals aware of possible hazards at the OU. Planning for emergency procedures
 would also be developed to deal with accidental exposures or sudden risk increases in affected
 areas.

 •      Capital Cost: $27,000
 •       Operations and maintenance (O&M) cost: $14,000
 •       Net present worth: $242,000

 Alternative 3 - Monitoring and Institutional Controls

This alternative contains all the provisions of Alternative 2, Limited Action and Institutional
Controls, plus ground water monitoring at OU-50.  Samples would be collected from monitoring
wells and would be analyzed for the risk drivers and any other contaminants of concern or  •-
parameters deemed necessary.
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  The frequency and duration of sampling will be determined in a subsequent remedial design.

  •       Capital Cost: $27,000
  •       Operations and maintenance (O&M) cost: $24,000
  •       Net present worth: $396,000

  Alternative 4 - Ground Water Extraction/GMF/Air Stripping/Discharge tn Surface Water an
  Institutional C
 This alternative includes ground water extraction through an extraction well or recovery trench
 system. Extracted ground water will pass through a granular media filtration (GMF) system to •
 remove suspended solids.  Filtered water will be treated in a low-profile air stripper to remove
 the volatile organic compounds.  Treated ground water would be discharged to the Back River.
 Sludges resulting from the filtration system would be characterized and properly disposed.  This
 alternative would also require future institutional controls.  Ground water use restrictions would
 be implemented until completion of the remedy.

 •        Capital Cost: $325,000
 •        Operations and maintenance (O&M) cost: $71,200
 •        Net present worth: $1,419,200

 Alternative $ - Ground Water Extraction/Chemical Precipitatinn/Air Stripping/Discharge to
 Surface Water and Institutional Controls

 This alternative is identical to Alternative 4, except that a chemical precipitation process
 (vertical sludge blanket clarifier) would be used to remove metals and suspended solids.  Since
 chemicals must be added to the extracted ground water, a step would be added to the treatment
 process to mix the chemicals and  ground water to form a slurry. This alternative would also
 require future institutional controls.  Ground water use restrictions would  be implemented until
 completion of the remedy.

•       Capital Cost: $325,200
•       Annual O&M Cost: $84,400
        Present Worth:  $1,622,200

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 IX.     Summary of Comparative Analysis of Alternatives

 During the detailed evaluation of remedial alternatives, each alternative is assessed against the
 following nine evaluation criteria: overall protection of human health and the environment;
 compliance with applicable and relevant and appropriate requirements (ARARs); long-term
 effectiveness and permanence; reduction of toxicity, mobility and/or volume (TMV); short-term
 effectiveness; implementability; cost; state acceptance; and community acceptance.

 A comparative analysis for the five alternatives based on these evaluation criteria is presented in
 the following sections.

 A.     Overall Protection of Human Health and the Environment

 Under Alternative 1, no remedial action would be implemented. The current site conditions and
 property use present no risk to human health because ground water is not used and constituents
 in soils do not pose an unacceptable risk under the industrial use scenario.  This alternative,
 however,  is not protective of an unrestricted use scenario.  Furthermore, since soils were
 evaluated only for industrial use scenarios, there may be potential risk under different types of
 scenarios.  Under Alternatives 2 and 3, institutional controls would be implemented.  The
 enforcement of the institutional controls, specifically the requirement for industrial use only and
 the prohibition of contact with, and consumption of, ground water would eliminate exposure
 pathways  that could present significant risk to future users. The institutional controls would
 mitigate both the carcinogenic and non-carcinogenic risks described in Section VII. Alternatives
 4 and 5 protect both human health and the environment through treatment of contaminated
 ground water thereby controlling the mobility of contaminants and reducing contaminant
 concentrations. Ground water use restrictions would be implemented until treatment of the
 ground water is complete. Also, institutional controls would prohibit use of the property for
 purposes other than industrial. These alternatives would be protective of human health and the
 environment under current and future use scenarios.  No significant risk to terrestrial or aquatic
 life was identified for OU-50 due to both a lack of sustainable habitat and insignificant levels of
bioaccumulating contaminants.
                                           15

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  B.     Compliance with ARARs

  Since this ROD involves an interim measure with respect to ground water contamination, final
  remediation goals and hence, ARARs, are not identified here. This ROD, however, does present
  a final action for soils. The soils under all five alternatives would be in compliance with all
  ARARs. (Specific ARARs for the remedy in this case are identified in Section XI of this ROD).

  C.      Long-term Effectiveness and Permanence

  Implementation of Alternative 1 could be effective and permanent in the long-term if considering
  soil alone because no significant contamination is present, assuming continued industrial use.
  However, in the long-term, individuals could be exposed to contamination through contact with
 ground water, and the property could be used for nonindustrial purposes, possibly increasing the
 risk to human health.  Therefore, Alternative 1 does not meet the requirements for long-term
 effectiveness and permanence.

 For Alternatives 2 and 3 The long-term effectiveness of the institutional controls will be
 contingent upon enforcement of the use restrictions by the Air Force through the Land Use
 Control Assurance Plan (LUCAP) as described in Section X. Implementation of Alternatives 2
 and 3 would maintain the industrial use of OU-50 and reduce the risk the future risk of exposure
 to ground water by the development and enforcement of restrictions. Because these restrictions
 would become a permanent part of the real estate documentation, through the submittal of the
 survey plat as described in Section X, and because the restrictions would be required to be
 included in any sales, transfers and/or lease agreements, this alternative would be a long-term
 and permanent remedial action.

 In addition to land use and ground water use restrictions described in Alternatives 2 and 3,
 Alternatives 4 and 5 include technologies that provide effective, permanent removal of
 contaminants from OU-50. Alternatives 4 and 5 include a system of pumping wells for ground
 water extraction.  The effectiveness of the extraction system can be evaluated based on pump
tests conducted in the proposed location. The effectiveness of these alternatives can be
evaluated through monitoring of the system performance.
                                          16

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  Alternative 4 includes GMF, an effective technology for the removal of suspended material and
  associated inorganic contaminants from the extracted ground water. Metals are removed less
  effectively unless some form of pretreatment is utilized. Solids removed in this process must be
  dewatered and disposed.  These solids are not expected to be hazardous because of the low metal
  concentrations found in the ground water, but testing would be necessary to properly
  characterize the solids for disposal.

 Alternative 5 includes chemical precipitation, an effective technology for removal of metals and
 suspended solids. This process would be more effective than GMF if low metals concentrations
 are required for discharge to surface water or if metals could cause fouling of the air  stripper.
 Precipitates generated in this process would require characterization prior to disposal, but
 because metals present in OU-50  are at relatively low levels, the residuals are not expected to be
 hazardous.

 Alternatives 4 and 5 propose an air stripping process for removal of organics in the ground
 water.  The effectiveness of this process is dependent on influent VOC concentrations, air-water
 ratio, and proper  design and sizing of the stripper. This technology does not destroy  the VOC
 compounds but rather eliminates them from the water stream.

 Alternatives 4 and 5 are expected to provide long-term effectiveness and permanence under both
 current and future use scenarios.

 D.      Reduction of Toxicity, Mobility, or Volume through Treatment

 The No Action, Limited Action, and Monitoring alternatives (Alternatives 1, 2 and 3) would not
 reduce the toxicity,  mobility, or volume of contaminants at the OU since the alternatives do not
 involve physical remedial actions.  Because ground water contamination is being addressed as a
 separate OU, the statutory preference for remedies that employ treatment that reduces the
 toxicity, mobility,  and/or volume a s a principle element will be addressed by the final  ground
 water response.

Alternatives 4 and 5 would reduce toxicity, mobility, and volume of contamination at  Site 61.
Toxicity would be reduced by removal of organic and inorganic contaminants by the various
treatment processes. Mobility would be reduced through extracting contaminated ground water

                                           17

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  in Alternatives 4 and 5, thereby controlling the rate and extent of migration.  Volume would be
  reduced through the removal and/or destruction of contaminants in ground water.

  E.      Short-term Effectiveness

  No impact to short-term effectiveness would be expected from the No Action, Limited Action, or
  Monitoring alternatives, Alternatives 1, 2, and 3, respectively.

  Conventional construction equipment would be used to complete the ground water extraction
  system, treatment facilities, and outfall  system in Alternatives 4 and 5; site workers would not
  face risks beyond those inherent in any construction project. Langley AFB employees and
 surrounding residents would be unaffected by construction activities.

 Design and construction of the remediation systems will require approximately 12-24 months,
 including detailed design and review, bid package preparation, contractor and equipment
 supplier selection, construction and installation of equipment, and start-up and shakedown.

 Under the RAGS Part C, the risks associated with the operation of an on-site air stripper should
 be considered short-term risks.  Although the operation may occur over a period of many years,
 exposure to emissions is viewed as a short-term risk. The site  and access restrictions that are
 included as part of this alternative will control and limit any potential exposure from the air
 stripper emissions in Alternatives 4 and 5.

 F.      Implementability

 The unit processes assembled hi Alternatives 4 and 5 are all commonly used in water treatment
 and are commercially available.  Electricity and a potable water supply are the only necessary
utilities and are currently available at the OU.

The No Action alternative would be the easiest to implement followed by the Limited Action
alternative and the Monitoring alternative (Alternatives 1, 2, and 3).

Alternative 4 would be the next easiest to implement but still will not require any extraordinary
effort since all treatment technologies are common and readily available.  The chemical

                                            18

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   precipitation process makes Alternative 5 less desirable than Alternative 4 unless lower metal
,   discharge limits are needed than can be achieved by GMF.

   The proposed discharge system, common to Alternatives 4 and 5, is implementable.  However,
   coordination with VDEQ would be required to determine the effluent discharge limits to the
   Back River.

   Administrative oversight would be necessary for all alternatives to ensure proper operation and
   maintenance of the chosen alternative. Monitoring of effluent contaminant concentrations, flow
   rates, residual testing, and effectiveness evaluations would be required for Alternatives 4 and 5.
  Duties associated with performing, coordinating, and managing these tasks are feasible and
  implementable.

  G.      Cost

  Estimated costs for the alternatives are summarized in Section VIE. These are preliminary
  estimates and are subject to change as the alternatives are refined (through pilot tests, etc.).

  The No Action alternative (Alternative 1) has no cost and the Limited Action alternative
  (Alternative 2) only a minimal cost consideration. The Monitoring alternative (Alternative 3) is
  the next least expensive alternative followed by Alternatives 4 and 5, respectively.

  Competitive bidding and/or vendor discounts may significantly reduce capital costs for the unit
  processes.

  O&M costs for the other alternatives is also uncertain since influent concentrations, both organic
  and inorganic, are not defined at this time.

  H.      State Acceptance

 The Virginia Department of Environmental Quality concurs with the selection of Alternative 3,
 Monitoring and Institutional Controls  as the selected remedy for this OU.
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  I.      Community Acceptance

  A public meeting on the Proposed Plan, which described Alternative 3 as the preferred
  alternative, was held on December 3, 1998 in Hampton, Virginia. Comments received orally
  and/or in writing at the availability session are referenced in the Responsiveness Summary
  (Section XIH of this ROD).

 X.      Selected Remedy

 Following review and consideration of the information in the Administrative Record file,
 requirements of CERCLA and the NCP, and the review of public comments on the Proposed
 Remedial Action Plan, the Air Force and EPA, in consultation with VDEQ, have selected
 Alternative 3: Monitoring and Institutional Controls as the remedy for OU-50. This remedy will
 prevent unacceptable exposure to soil and groundwater.  The total present worth costs of the
 selected remedy are estimated at $396,000.00

 Based on available information, the Air Force and EPA believe that the selected remedy would
 be protective of human health and the environment, would be cost-effective, and would provide
 the best balance of trade-offs among the alternatives with respect to the evaluation criteria.

 The selected remedy for OU-50 includes the following major components:

 1)      Land use restrictions to prevent non-industrial use of the property, with the exception of
        the non-residential waterfront development plans discussed in Section VI  and to
        maintain the integrity of the current asphalt parking lot;;
2)      Ground water use restrictions to prohibit use of the ground water for purposes
        other than monitoring;
3)      Within 90 days of ROD signature, the Air Force shall produce a survey plat prepared by
        a professional land surveyor registered by the Commonwealth of Virginia indicating the
        location and dimensions of OU-50 and the extent of soil and ground water
        contamination;
4)      The Air Force shall supply a copy of the plat and ensure incorporation of these
        restrictions into any real property documents necessary for transferring ownership from
        the United States, in the unlikely event that the United States sells or transfers the

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        property. The real property document would also include a discussion of the National
        Priorities List (NPL) status of this Site, as well as a description of the soil and ground
        water contamination. The precise boundaries of the areas in which residential use is
        prohibited shall be fixed during the development of the Land Use Control
        Implementation Plan described  later in this section. The Air Force shall submit the
        survey plat to the City of Hampton recording authority for the limited purpose of
        providing public notice of the environmental conditions of and limitations on the use of
        the property.  No property right or interest is intended to be nor shall be created by such
        notice.  In addition, the Air Force shall enter a note, in the local land recording office, to
        the real property document evidencing U.S. ownership of the property on which the OU
        is located that shall notify interested parties that the site was previously used to manage
        paint shop substances and waste;
5)      Ground water monitoring to ensure contaminated ground water is not impacting the
        Back River, but this is not the final remedy for ground water.  Ground water will be
        addressed in a final action on an installation-wide basis as a separate OU. Specifics of
        the monitoring program will be developed by the Air Force, the United States
Environmental Protection Agency and the Virginia Department of Environmental
Quality and presented in a monitoring plan.

Within 90 days of the execution of this ROD, the LAFB shall develop a Land Use Control
Implementation Plan (LUCIP) for OU-50 with the concurrence of EPA Region m and in
consultation with the Commonwealth of Virginia.  The LUCIP shall include:

        (1) a description and the location of OU-50, including a map, a description of the OU's
        approximate size and a description of the COCs;
        (2) the land use control objectives (LUCs) selected above;
        (3) the particular controls and mechanisms to achieve these goals;
        (4) a reference to this ROD; and;
        (5) any other pertinent information.

Within 180 days following the execution of this ROD, the Air Force, with the concurrence of
EPA Region ffl and in consultation with the Commonwealth of Virginia, shall develop a
Memorandum of Agreement on Land Use Control (MOALUC) for LAFB.  The MOALUC shall
contain Base-wide periodic inspection, condition certification and agency notification

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  procedures designed to ensure the maintenance by LAFB personnel of any site specific LUCs
  deemed necessary for future protection of human health and the environment, including LUCs
  selected in this ROD. A fundamental premise underlying execution of the MOALUC is that,
  through the Air Force's substantial good-faith compliance with procedures called for therein,
  reasonable assurances will be provided to USEPA and the Commonwealth of Virginia as to the
  permanency of those remedies which include the use of specific LUCs.

  Although the terms and conditions of the MOALUC will not be specifically incorporated or
  made enforceable as to this or any other ROD, it is understood and agreed by the Air Force,
  USEPA and the Commonwealth of Virginia that the contemplated permanence of the remedy
  reflected herein shall be dependent upon LAFB's good-faith compliance with the MOALUC.
  Should such compliance not occur or should the MOALUC be terminated it is understood that
  the protectiveness of the remedy concurred in may be reconsidered and that additional measures
  may need to be taken to ensure necessary future protection of human health and the environment.

 XI.     Statutory Determinations

 Under CERCLA Section 121, EPA must select remedies that are protective of human health and
 the environment, comply with applicable or relevant and appropriate requirements (unless a
 statutory waiver is justified), are cost-effective, and utilize permanent solutions and alternative
 treatment technologies or resource recovery technologies to the maximum extent practicable. In
 addition, CERCLA includes a preference for remedies that employ treatment that permanently
 and significantly reduce the volume, toxicity, or mobility of hazardous waste as their principle
 element.  The following sections discuss the remedy in light of these statutory requirements.

 A.      Protection of Human Health  and the Environment

 The selected remedy, Alternative 3, would protect human health and the environment.  The
 institutional controls will mitigate both the carcinogenic and non-carcinogenic risk described in
 Section VII.

 B.     Compliance with ARARs

Since the remedy regarding ground water is an interim measure, final cleanup objectives and

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  ARARs will be addressed in a subsequent basewide ground water ROD. This ROD, however
  does present a final action for soils. The selected remedy will comply with all ARARs (there are
  no chemical-, location-, or action- specific ARARs).

  C.     Cost Effectiveness

  The selected remedy, Monitoring and Institutional Controls, was chosen because it provides the
  best balance among criteria used to evaluate the alternatives considered in Section IX. The
  alternative was found to achieve both adequate protection of human health and the environment
 and to meet statutory requirements of Section 121 of CERCLA. The selected remedy was found
 to be cost-effective. The cost of Alternative 3 has been established to be $396,000.00.

 D.     Utilization of Permanent Solutions and Alternate Treatment Technologies
        or Resource Recovery Technologies to the Maximum Extent Practicable

 The Air Force, EPA and VDEQ have determined that the selected remedy represents the
 maximum extent to which permanent solutions and treatment technologies can be utilized in a
 cost-effective manner for OU-50. The ground water portion of this action, however, is interim
 and is not intended to utilize permanent solutions and alternative treatment (or resource
 recovery) technologies to the maximum extent practicable.

 E.      Preference for Treatment as a Principle Element

 The selected remedy for OU-50, Monitoring and Institutional Controls, does not satisfy the
 statutory preference for treatment as a principal element of the remedy.  With respect to the
 soils, as long as the property is not used for non-industrial purposes, a treatment remedy is not
 required. As for the ground water, since the selected action does not constitute a final remedy,
 the statutory preference for remedies that employ treatment that reduces toxicity, mobility, or
 volume as a principal element will be addressed by the final ground water response action.

 XII.    Significant Changes from Proposed P|ap

The proposed plan for OU-50 was released for public comment on November 30, 1998. The
proposed remedial alternative identified in the proposed plan was Monitoring and Institutional

                                          23

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  Controls. The Air Force, EPA and VDEQ reviewed and considered all comments received
  during the public meeting and during the public comment period.  Since the public comment
  period ended, the Air Force has developed waterfront beautification plans which include
  changes to the use of the waterfront property at OU-50, specifically, the inclusion of a walkway
  along the shoreline.  These plans are discussed in detail in Section VI.  EPA independently
  assessed  the potential future recreational use of OU-50 and found that although the recreational
  user would have a higher risk than a construction worker, neither a hazard index greater than 1
  nor a cancer risk greater than 1 x 10*4 is expected.7-1  Therefore, the limitations of the institutional
  controls,  as presented in the Proposed Plan, have been slightly altered to allow for walkway
  installation.

 XIII.   Responsiveness Summary

 A.     Overview

 In a proposed plan released for public comment on November 29, 1998, Langley AFB, with the
 support of EPA and VDEQ, identified Monitoring and Institutional Controls as the preferred
 remedial alternative for OU-50.* There were no written comments received as a result of the
 public comment period. There were no written comments submitted during the December 3,
 1998 availability session held in Hampton, Virginia. There were four questions presented orally
 at the availability session concerning OU-50.  After evaluating and addressing  these comments,
 Langley AFB and EPA, with the support of VDEQ, have selected Monitoring and Institutional
 Controls as the remedy for OU-50. Comments and the associated responses of Langley AFB,
 EPA, and  VDEQ are described below after a brief discussion of community involvement to date.

 B.     Community Involvement to Date

 The Langley AFB Partnership established a public comment period from November 29, 1998 to
 December 29, 1998 for interested parties to comment on the proposed plan for OU-50. These and
 all other documents considered or relied upon during the remedy selection  process for OU-50 are
 included in the Administrative Record, which has been established in two information
repositories accessible to the public since the beginning of the  public comment period for OU-
50. An availability session was held at the Virginia Air and Space Center, Hampton, Virginia,
on December 3,  1998 to present the proposed plan, answer questions, and  accept both oral and

                                         24

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 written comments on the OU-50 remedial alternative. Four persons attended this session.

 This Responsiveness Summary, required by CERCLA, provides a summary of citizens'
 comments received during the public meeting and the responses of the Air Force, EPA, and
 VDEQ.  Responses to these comments are included in the section below.

 C.     Summary  of Comments Received During Public Comment Period and
        Comment  Responses

 Comment #1:

 Even though contamination has been found at the OU, the plan is only to monitor, not remove
 anything from the OU? Will the contamination dissipate over time?

 Response #1:

 Yes, the groundwater contamination will dissipate over time and because there is no impact on
 human health or the environment under the current land use, no removal is warranted.
 Groundwater monitoring is important so that we can ensure that there is no future impact on the
 Back River.  Initially, more comprehensive monitoring would be conducted.  After two quarters
 of monitoring results are reviewed, some chemicals may fall out or a decision may be made to
 monitor less frequently. If something shows up that is of potential concern then appropriate
 steps would be taken. The ground water monitoring data also would be evaluated as part of the
 five-year review.  In addition, there is a base-wide ground water monitoring effort underway.
 The Air Force, EPA and VDEQ, however,  decided not to delay progress on this OU, allowing
 this remedy to move forward apart from the base-wide effort.

 Comment #2:

Who would be the contractor for this work?

Response #2:

For the ground water monitoring at OU-50 (Site OT-61) IT Corporation would do the work.

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 Comment #3:

 I was aware of the removal of an underground storage tank from this OU in the past, but I did not
 know of the other aspects associated with remediation of the OU.

 Response #3:

 The underground storage tank was removed in 1993. The existing contamination is probably
 associated with the paint shop operations that were conducted at the OU.

 Comment #4:

 Is there any natural attenuation involved too, or is just dissipation that will occur?

Response #4:

Both natural attenuation (where there is an actual breakdown of the chemicals) and dissipation
(where the contamination spreads out and is found in even lower concentrations) of the
groundwater will occur at the OU.
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 X.     References

 ^ersar, Inc., 1996, Langley Air Force Base Basewide Standard Operating Procedures:
 Background Information Document, January 19.

 2Radian Corporation, 1996, OU Inspection and Screening Risk Assessment Report for 33
 Installation Restoration Program OUs, Draft, Langley Air Force Base, Virginia, February.

 3Radian International, 1998, Final Installation Restoration Program (IRP) Conceptual
 Hydrogeological Model Report for Langley Air Force Base, May.

 4Langley Air Force Base, 1998, Final Proposed Plan for Remedial Action at Operable Unit 50,
 Langley Air Force Base, Virginia, November.

 5PMC, 1998, Final Remedial Investigation and Feasibility Report for IRP Site SS-61, Langley
Air Force Base, Virginia, 10 July.

6U.S. Environmental Protection Agency, 1989, Risk Assessment Guidance for Superfund,
 Volume I:  Human Health Evaluation Manual (Part A), Interim Final, Office of Emergency and
Remedial Response, Washington, DC, EPA/540/1-89/002.

7Driscoll, Stacie, 1999.  Personal communication: Letter from Stacie Driscoll,  U.S. EPA Region
III. 6 May.

8Driscoll, Stacie, 1999.  Personal communication: Letter from Stacie Driscoll,  U.S. EPA Region
 in.  17 June.
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APPENDIX A
  Tables

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                                                   Table 1
                     Summary of Operable Units Under CERCLA Investigation
                                    Langley Air Force Base, Virginia
                                                 Pagel of 3
    OU Name/IRP OU Name
           Findings
                                                                           Current Status
 OU-21/LF-01
 Former Landfill, End of 08/26
 Runway
 Contaminants of Potential
 Concern (COPCs) - pesticides
 and metals in the ground water
 and soil.
 In the remedial investigation (Rl) phase. A draft
 Rl report has been submitted and reviewed. A
 separate basewide ecological risk assessment
 is currently underway.
 OU-22/WP-02
 Former Waste Water Treatment
 Plant, Bldg 724
 COPCs - pesticides and metals
 in the ground water and soil.
 In the Rl phase. A draft Rl report will be
 submitted by mid-1999.
 OU-23/LF-05
 Former Landfill in the Shellbank
 Area
 COPCs - pesticides, volatile
 organic compounds (VOCs),
 and metals in the ground water;
 pesticides and metals in the
 surface water; and semivolatile
 organic compounds (SVOCs)
 and metals in the soil.
 In the Rl phase. A draft Rl report has been
 submitted and reviewed. A separate basewide
 ecological risk assessment is currently
 underway.
OU-24/OT-06
Former Entomology OU,
Shellbank Area
 COPCs - pesticides, VOCs,
 SVOC, and some metals in the
 ground water; SVOCs,
 pesticides and some metals in
 the soil.
In the Rl phase. A draft Rl report has been
submitted and reviewed. A separate basewide
ecological risk assessment is currently
underway.
OU-25/LF-07
Former Landfill, Shellbank Area
COPCs - pesticides and some
metals in the ground water;
dieldrin in the soil.
In the Rl phase. A draft Rl report has been
submitted and reviewed.  A separate basewide
ecological risk assessment is currently
underway.
OU-26/WP-08
Former Waste Water Treatment
Plant, Lighter Than Air (LTA) Area
COPCs - some pesticides and
metals in the ground water;
dieldrin in the soil.
In the Rl phase. A draft Rl report has been
submitted and reviewed.
OU-28/LF-10
Former Landfill, Golf Course
COPCs - VOCs, metals and
some pesticides in the ground
water VOCs and polychlorinated
biphenyte (PCBs) in surface
water; some metals in the soy.
In the Rl phase. A draft Rl report has been
submitted and reviewed.  A separate basewide
ecological risk assessment is currently
underway.

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     OU Name/IRP OU Name
           Findings
                                                                             Current Status
  OU-29. LF-11
  Former Landfill, Tabbs Creek
  Area
  COPCs - VOCs, pesticides,
  metals and PCBs in the ground
  water; some metals in the
  surface water; SVOCs, metals,
  and PCBs in the soil.
 In the Rl phase. A draft Rl report has been
 submitted and reviewed. A separate basewide
 ecological risk assessment is currently
 underway.
  OU-30/LF-12
  Former Landfill, Munitions
  Storage area, Northwest Area of
  Base
 COPCs - VOCs and metals in
 the ground water; metals and 2,4
 DB in the surface water; SVOCs
 and nickel in the soil.
 In the Rl phase. A draft Rl report has been
 submitted and reviewed. A separate basewide
 ecological risk assessment is currently
 underway.
 OU-31/LF-13
 Former Landfill Munitions Storage
 Area, Northwest Area of Base
 COPCs - Aldrin, alpha-BHC and
 some metals in the ground
 water; VOCs, SVOCs, metals
 and PCBs in the surface water.
 In the Rl phase. A draft Rl report has been
 submitted and reviewed.  A separate basewide
 ecological risk assessment is currently
 underway.
 OU-32/WP-14
 Former Chemical Leach Pit,
 Firing-ln Abutment Building 1303
 COPCs - pesticides, SVOCs,
 and some metals in the ground
 water arsenic and dieldrin in the
 soil.
 In the Rl phase. A draft Rl report has been
 submitted and reviewed.  A separate basewide
 ecological risk assessment is currently
 underway.
 OU-33/LF-15
 Former Landfill, Willoughby Point
 COPCs - VOCs, SVOCs,
 pesticides and metals in the
 ground water pesticides and
 metals in the surface water.
 In the Rl phase.  A draft Rl report has been
 submitted and reviewed.  A separate basewide
 ecological risk assessment is currently
 underway.
 OU-34/LF-17
 Former Landfill, LTA Area
 COPCs - VOCs, pesticides and
 some metals in the ground
 water; dieldrin and some metals
 (mainly lead) in the soil.
 In the Rl phase/ A draft Rl report will be
 submitted by mid-1999.
 OU-35/LF-18
 Former Landfill, Northwest corner
 of Base
COPCs - pesticides in the
ground water pesticides and
metals in the surface water
SVOCs and manganese in the
surface soil; detta-BHC, and
metals in the sediment
In the Rl phase. A draft Rl report has been
submitted and reviewed. A separate basewide
ecological risk assessment is currently
underway.
OU-37/LF-22
Former LandfiB, Willoughby Point
  OPCs - pesticides and metals
 n the ground water alpha-BHC,
delta-BHC and metals in the
surface water.
In the Rl phase. A draft Rl report has been
submitted and reviewed. A separate basewide
ecological risk assessment is currently
underway.
OU-40/OT-25
Old Entomology Building and
Former Storage Area, Bldg 965
  OPCs - pesticides in the
ground water and soil.
 n the Rl phase. A separate basewide
ecological risk assessment is currently
underway.
OU-42/OT-38A and B
Four Waste OH and Trash Burn
Areas, Basewide
Risk assessments showed no
significant risk to human health
or the environment from soite
The Record of Decision (ROD) for soils was
signed on January 14, 1999. Ground water
ROD wiy follow at a later date. The final Rl
report was submitted in September 1998.

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OU Name/IRP OU Name
OU-44/FT-41
Former Fire Training Area,
Firing-ln Abutment, Bldg 1303
OU-47/OT-51
Former Electrical Substation,
Shellbank Area, Bldg 82
OU-48/OT-55
Civil Engineering Yard,
Underground Petroleum
Contamination
OU-49/OT-56
Silver Contamination in Storm
Sewers, Basewide
OU-50/SS-61
Old Civil Engineering Paint
Shop/Marina
OU-51/SS-63
Back River Sediments
OU-52/OT-64
Ground water Contamination,
Basewide
Findings
COPCs - VOCs, pesticides,
dioxins, and some metals in the
ground water SVOCs, dioxins
and some metals in the surface
water.
COPCs - pesticides, PCBs and
lead in the soN.
COPCs - pesficides and dieldrin
in the ground water; pesticides
and PCBs in the soil.
COPCs - metals and VOCs in
surface water and metals,
SVOCs and pesticides in
sediment
COPCs - VOCs in the ground
water and soil.
COPCs - pesticides, metals, and
PCTs in the sediment
COPCs - pesticides and metals
n the ground water.
Current Status
In the Rl phase. A draft Rt report has been
submitted and reviewed. A separate basewide
ecological risk assessment is currently
underway.
The ROD for soil was signed on January 14,
1 999. Ground water ROD will follow at a later
date.
In the Rl phase. A draft Rl report is due to be
submitted by mid-1 999.
In the feasibility study (FS) phase. The FS is
due to be finalized by mid-1 999.
This OU is currently in the Record of Decision
Phase.
In the preliminary assessment/OU inspection
(PA/SI) phase. The draft PA/SI report is due to
be submitted by the end of 1 998
In the scoping phase. The long-term
monitoring project is due to be awarded by mid-
1999.

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                                Table 2
Maximum Groundwater Concentrations Exceeding Residential Tap water Levels




                               Page 1 of 1
Analyte
Acetone
Arsenic
Barium
Benzene
Carbazote
Carbon Disulfide
Chloroform
Chloromethane
Dieldrin
Ethylbenzene
Iron
Manganese
Napthalene
PCB-1260 (Arochlor 1260)
Thallium
Toluene
Value (ug/l)
440.00
252.00
1030.00
2400.00
7.00
130.00
2.00
54.00
0.0200
880.00
11700.00
2370.00
190.00
0.500
14.90
150.00
Screening Level (ug/l)
370.00
0.045
260.00
0.3600
3.400
100.00
0.1500
1.400
0.0042
130.00
1100.00
18.00
150.00
0.0087
0.290
75.00

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                           Table 3
Maximum Soil Concentrations Exceeding Industrial Screening Levels




                          Page 1 of 1
Analyte
Arsenic
Benzo(a)Pyrene
PCB-1260
Value (mg/kg)
17.30
4400.00
1200.00
Screening Level {mg/kg)
3.80
780.00
740.00

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APPENDIX B
  Figures

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                          Goodwin Islands

                        Reference Location

                            20 Miles
  BETHEL MANOR
OFF-BASE HOUSING
    Figure 1.  Location Map, Langley Air Force Base, Virginia

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Figure 2. Base Map of Ungley AFB Showing the Localion of the Slle
                       fSS-61/OU-sm

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Will remain
asphalt
Figure 4. Waterfront Development Plan

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APPENDIX C
  Glossary

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Administrative Record: A collection of documents containing all the information and reports generated during the
entire phase of investigation and cleanup at the OU and used to make a decision on the selection of the preferred
alternative under CERCLA.

Carcinogenic Risk: Cancer risks are expressed as numbers reflecting the increased chance that a person will develop
cancer if exposed to chemicals or substances. For example, EPA's acceptable risk range for Superfund OUs is      1
x 10"4 to 1 x 10"6. This means that the probability of cancer should not be greater than 1 in 10,000 chance to a 1  in
1,000,000 chance above background.

Comprehensive Environmental Response, Compensation and Liability Act (CERCLA): A federal law,
commonly referred to as the Superfund Program, passed in 1980 that provides for the cleanup and emergency
response in connection with numerous existing inactive hazardous waste disposal OUs that endanger public health
and safety of the environment.

Chemicals of Potential of Concern (COPCs): Chemicals, either present at the OU as a result of historical activities
or of likely concern to human health and the environment, which are evaluated in the risk assessment.

Ecological Risk Assessment: An evaluation of the risk posed to the environment if remedial activities are not
performed at the OU.

Exposure Pathways:  Describes the course a chemical or physical agent takes from the source to the exposed
individual.  Elements of the exposure pathway are: (1) the source of the released chemical; (2) the contaminated
medium (e.g., soil); (3)  a point of contact with the contaminated medium; and (4) an exposure route (e.g., ingestion,
inhalation) at a contact point.

Hazard Index (HI): A number indicative of non-carcinogenic health effects which is the ratio of the existing level of
exposure to an acceptable level of exposure. A value equal to or less than one indicates that the human population is
not likely to experience adverse effects.

Human Health Risk Assessment: An evaluation of the risk posed to human health should remedial activities not be
implemented.

Installation Restoration Program (IRP): Program established by the United States Air Force to systematically
identify and remediate contaminated OUs. The IRP was designed to be consistent with EPA rules and guidelines.


Lowest-Observed-Adverse-Effect Level (LOAEL):  The lowest exposure level at which there are statistically or
biologically significant  increases in frequency or severity of adverse effects between the exposed population and its
appropriate control group.

No-Observed-Adverse-Effect Level (NOAEL): An exposure level at which there are no statistically or biologically
significant increases in the frequency or severity of adverse effects between the exposed population and its appropri-
ate control; some effects may be produced at this level, but they are not considered as adverse, nor as precursors to
adverse effects. In any  experiment with several NOAELs, the regulatory focus is primarily on the highest one,
leading to the common usage of the term NOAEL as the highest exposure without adverse effect.

Operable Unit (OU): A discrete portion of a OU or a discrete action representing an incremental step in the
investigation and remediation of hazardous substances at a facility.

Proposed Plan: A document that presents a proposed cleanup alternative and requests public input regarding the

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 proposed alternative.


 Record of Decision (ROD): A legal document that describes the cleanup action or remedy selected for a OU, the
 basis for the choice of that remedy, and public comment on alternative remedies.

 Remedial Action: Implementation of plans and specifications, developed as part of the design, to remediate a OU.

 Remedial Investigation (RI): Part of a study of a facility that supports the selection of a remedy for a OU where
 hazardous substances have been disposed.  The RI identifies the nature and extent of contamination at the facility.

 OU: The facility and any other areas in close proximity to the facility where a hazardous substance, hazardous waste
 hazardous constituent, pollutant, or contaminant from the facility has been deposited, stored, disposed of, or placed or
 has migrated or otherwise come to be located.


 OU Inspection (SI): The SI determines if the OU presents an immediate threat that requires prompt response action
 because the OU may pose a threat to human health and/or the environment.

 OU-Related Risk: Cancer and non-cancer risk estimates that are based on contaminants present in environmental
media due to OU-specific human activities at Langley AFB, but that exclude the contribution of background
contaminant concentrations.

Superfund Amendments and Reauthorization Act (SARA): An amendment to CERCLA enacted in 1986.

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                  Reproduced by NTIS

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