PB99-963119
                              EPA541-R99-090
                              1999
EPA Superfund
      Explanation of Significant Difference
      for the Record of Decision:
      Pensacola Naval Air Station OU 1
      Pensacola, FL
      9/23/1999

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                                                                          1
              UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                                REGION 4
                          ATLANTA FEDERAL CENTER
                            61 FORSYTH STREET
                         ATLANTA. GEORGIA 30303-8960
                                 as-,
 CERTIFIED MATT,
 RETURN RECEIPT  PRQUESTED

 4WD-FFB

 Commanding Officer
 Naval Air Station Pensacola
 190 Radford Boulevard
 Pensacola,  Florida 32508-5217
SUBJ:
        Explanation of Significant  Differences
        Operable Unit 1, Site  1
        Naval Air Station Pensacola
        Pensacola,  Florida
 Dear Sir:

     The U.S.  Environmental Protection Agency (EPA)  R^aion   „„«,
   viewed the  abov<=» snh,-ior.i- decisi on-rfnr-Mma^i   5  -«~gion •* u
                            aecision document and concurs with the
                            differences  for  the  Remedial Action at
 0^™=,*--,!  -"— -7	-(  -1-0 supported by the previously comnleted
 *™enCInR;^?;tlOIV Feasibili^ «««* •«• Busline SE"1

     The  significant difference to the August 1998 Record of
 Decision (ROD)  is  the discharge location of  the  groJndwfter'  The  "
 groundwater is  now being discharged into the SLy^  £as?ewSt-r
 system where  it will  undergo treatment.  The  original selected
 remedy involved extracting groundwater downgradient  of  the
 landfill, treating it,  then discharging into  Wetland 3  on base.

     This action is protective of human health and the
environment,  complies  with Federal and State  requirements that
are legally applicable or relevant and appropriate tothl
remedial action and is cost effective.      uP"-*ce co tne

                                    Singe.rely,   \

                                                -1\^
                                    LichardND. Green,  Director
                                    Waste Management  Division



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 CERTIFIED MAIL
 RETURN RECEIPT REQUESTED

 4WD-FFB                                                               t

 Commanding Officer                                                    .,
 Naval Air Station Pensacola                                           f
 190 Radford Boulevard
 Pensacola,  Florida 32508-5217                                          x

 SUBJ:   Explanation of Significant Differences
        Operable Unit l,  Site 1
        Naval Air Station Pensacola
        Pensacola,  Florida

 Dear Sir:

     The U.S.  Environmental  Protection Agency (EPA)  Region  4 has
 reviewed  the above subject  decision document and concurs with the
 explanation of  significant  differences for the  Remedial Action at
 Site l.   This remedy is  supported by the previously completed
 Remedial  Investigation,  Feasibility Study and Baseline Risk
 Assessment  Reports.

     The significant  difference to the August 1998 Record of
 Decision  (ROD)  is  the discharge location of the groundwater. The
 groundwater is  now being discharged into the Navy's wastewater
 system where it will undergo treatment.  The original selected
 remedy involved extracting  groundwater downgradient of the
 landfill, treating it, then discharging into Wetland 3 on base.

     This action is  protective of human health  and  the
 environment,  complies with  Federal and State requirements that
 are  legally applicable or relevant and appropriate  to the
 remedial action and  is cost effective.

                                    Sincerely,


                                    Richard D. Green, Director
                                    Waste Management  Division

 cc:  Elsie  Munsell,  Deputy  Assistant  Secretary  of the Navy
     Ron Joyner, NAS  Pensacola
     Bill Hill,  SOUTHDIV
     Joe Fugitt, FDEP

GOT:gt:FFB:28538:9-14-99:OU1ESD.CON
Towr.sWd    Marshall   Bozeman.

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        F !NAL DECLARATION OF THE EXPLANATION OF SIGNIFICANT DIFFERENCES

    Sltfe Ndltie and Location
*   Site 1, Inactive Sanitary Landfill
    Naval Air Station Pensacola
 /  Pensacola, Florida

    Statement of Basis and Purpose
    The U.S. Navy,  as the lead agency, has prepared an Explanation of Significant Differences (ESD) for
    Site 1 (Operable  Unit 1)  — Inactive Sanitary Landfill, Naval Air Station Pensacola.  This ESD is issued
    under the public participation  requirements of Section  1 17(c) of the Comprehensive  Environmental
    Response, Compensation, and Liability Act, Section 300.435(c)(2)(i) of the National Contingency Plan.
    The ESD is part of the site's Administrative Record.

    The Navy, with concurrence from the United States Environmental Protection Agency (USEPA) and the
    Florida Department of Environmental Protection (FDEP), selected a remedy that called  for discharging
    treated groundwater into a nearby wetland (as documented in the August 21, 1998  Record of Decision
    tftOD] for Site t). Since that time, the Navy has considered and adopted a change to  the selected cleanup
    remedy.  The modification was riecessary because the Navy's wastewater treatment system is better able
    to handle daily discharges of low chemical concentrations than an annual discharge of more concentrated
    chemicals.  This change will also increase cost effectiveness while continuing to protect human health and
    the environment.
              t of the Selected Retnedy and Significant Differences
    The original selected remedy for Site I involved extracting groundwater downgradienfof the landfill,
    treating it, then discharging the treated water into Wetland 3 on the base. The significant difference in the
    1999 modification is the discharge location.  Groundwater wilt not be treated and then discharged into the
    wetland, but groundwater will be discharged directly into the Navy's wastewater system for treatment.
    This change Will still protect human health and the environment and meets the ARARs identified at the time
    the original ROD Was Signed.  New ARARs are listed in Table 1 . USEPA and FDEP have concurred with
    the modification to the remedy for Site 1.

                                                tablet
                                  New ARARs for the Site t Selected Remedy
                                                                                 Status
      Florida Pretreattnent Requirements for Existing and Hew Sources of Pollution        Relevant and Appropriate
      Tide 62 Chapter 62-625

     Statutory Determinations
5    Considering «>» :uinges that have been made to the selected remedy, the Navy (with USEPA and FDFP
     concutre^.-  '-•=>'••   •   b? remedy remains protective of human  health and the enviror"^"'.  '•••
{    effective, i ........... •• ••'• -'^1-en1 i:'«j state requi-erne"" i'iep.tifieH ir th-? PT •; '.rri: -"'•"  • " '••'••' "•
               '"" '    ' '  ".•?"'.' ' ~'  \~." "~ i- the tin'v ''"•"   -;-:-
     Commanding Officer
     NAS Pensicob.

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