PB96-963106
                                 EPA/ESD/R01-96/127
                                 September 1996
EPA   Superfund
       Explanation of Significant Difference
       for the Record of Decision:
       Commencement Bay, Nearshore/Tideflats
       Operable Unit 2, Pierce County, WA
       7/2/1996

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               EXPLANATION OF SIGNIFICANT DIFFERENCE
               TO THE ASARCO TACOMA SMELTER FACILITY
                        RECORD OF DECISION
                   RUSTON AND TACOMA, WASHINGTON
A.   Introduct ion

     1.   Site  name  and location:   Former Asarco Tacoma Smelter
          Facility and Slag  Peninsula  (the  "Site"), Operable Unit
          2 of  the Commencement  Bay Nearshore Tideflats Superfund
          Site,  Ruston and Tacoma,  Washington.

     2.   Lead  Agency:   U.S.  Environmental  Protection Agency
           (EPA) .

     3.   Support  Agency:  State of Washington, Department of
          Ecology.

     4.   Legal  authorities  for  cleanup action:  The
          Comprehensive Environmental  Response, Compensation, and
          Liability  Act, .as  amended (CERCLA), 42 U.S.C. § 9601,
          et seq., and the National Oil and Hazardous Substance
          Pollution  Contingency  Plan  (NCP),  40 C.F.R. Part 300.

B.   Summary of  Site History.  Contamination Problems, and
     Selected Remedy

     ASARCO, Inc.  (Asarco) has owned and/or operated the Asarco
Tacoma Smelter property since 1905.  Asarco used the property
initially as a  lead  smelter  and  refinery, and converted it in
1912 into a facility to smelt and refine copper from copper-
bearing ores and concentrates shipped  in from other locations.
Slag, a black,  rock-like,  by-product of Asarco's copper smelting
operations was either  used by Asarco as a fill to extend the
shoreline of the Site  or sold to local entities and companies for
their use as fill.   Asarco closed the  Smelter in 1985.

     Past smelter  operations  and emissions  resulted in releases
of hazardous substances, including  arsenic  and other heavy
metals, at and  in  areas surrounding the smelter.  Metals that are
in the slag or soil  have migrated to surface and ground water at
the Site.  Ores  which  were smelted  at  the Site left metals in the
buildings and structures on  the  Site, most  of which were removed
pursuant to the  Asarco Demolition Consent Decree in May 1992.

     EPA issued  the  Record of  Decision  (ROD) for the.final
remediation of the Site in March 1995.  EPA determined that
cleanup actions  were necessary because current conditions on the
Site posed unacceptable risks  over  the long-term to future
residents,  potential workers,  and visitors  and to the ground
water discharging  to Commencement Bay.

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     One critical component of the ROD is construction of a RCRA-
compliant On-Site Containment Facility (OCF).  Pursuant to the
ROD, the OCF will contain the Site's RCRA characteristic source
area soils, granular fill and demolition debris.  The OCF's
liner, cap, leak detection, collection and removal system,
leachate collection and removal system and surface run-on and
run-off control systems are required to meet federal and state
standards for a hazardous waste landfill.  The ROD states that
the OCF shall be constructed "northeast of the arsenic kitchen
area."  ROD, Section 9 .1". 2  (a).

C.   Summary of the Explanation of Significant Difference to the
     Asarco Tacoma Smelter Facility Record of Decision

     EPA has selected a new, on-site location for the OCF after
extensive review and exploration of the original OCF location
identified in the ROD.  Asarco, with EPA approval, investigated
subsurface conditions of the proposed OCF location between May
and July, 1995.  The investigation revealed that the OCF location
identified in the ROD was unacceptable in its existing state.

     Data from the investigation showed the proposed OCF location
was underlain by a buried alluvial valley, partially filled with
loose sands and silts, and partially by soft clay and peat.  The
investigation revealed that the sandy and silty materials are
likely to liquify in the event of a severe seismic event,
resulting in slope spreading and settlement.  In addition, the
side slopes of the buried alluvial valley appear to be rather
steep, and differential settlement could cause severe local
deformation and stress to liners and collection systems.
Furthermore, clayey and silty alluvial deposits may result in
excessive settlement under the load of the OCF or bearing
capacity failure.  Bearing capacity failure would cause large
shear strains that would severely damage the OCF.

     Due to the high seismic risk of the area, and the excessive
risk posed by potential bearing capacity failure, settlement and
slope spreading, EPA determined, that further geotechnical
investigation was required to find an alternative OCF location.
Asarco performed additional field investigation and laboratory
testing in the parking lot area of the site, off Bennett Street,
in September 1995.  Preliminary analysis indicated that this area
was geotechnically acceptable, and not subject to bearing
failure, excessive settlement or slope instability.  As a result,
EPA has selected this area as the new location for the OCF.

D.  Public Participation Activities

     EPA held two public comment periods from September 20,  1995,
to November 20, 1995 on moving and changing the location of  the
OCF from northeast of the arsenic kitchen area to the parking lot
area off Bennett Street  (see Superfund Fact Sheets included  as

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 Attachments 1 and 2).   The attached Fact  Sheets  were  distributed
 to the Asarco mailing  list of approximately 800  individuals.   In
 addition,  the Fact Sheets were made available for public  review
 at the information repositories listed on the back page of  the
 Fact  Sheets (see Attachments 1 and 2).  EPA and  Asarco also
 sponsored  community meetings where the geotechnical information
 and relocation of the  OCF were discussed.   EPA did not receive
 any'  written comments  in response to the  public  comment periods,
 and participants at the community meetings did support changing
 the OCF's  location based on Asarco's findings.

 E.  Administrative Record

      This  BSD,  the attached Fact Sheets,  the Record of Decision,
 the Asarco geotechnical reports and other reports and information
 related to the Asarco  Tacoma Smelter Site are part of the
 administrative record  for the Site.   The  administrative record is
.available  for public review at the following locations:

      1.  In.Seattle:   Environmental Protection Agency
                       1200 Sixth Ave.

      2.  In Tacoma:  Tacoma Public Library
                     Main Branch
                     1102 Tacoma Avenue South
                     Northwest Room

 F.  Affirmation of Statutory Determinations

      Considering the new information that has developed and the
 change that has been made to the selected remedy,  EPA believes
 that  the remedy remains protective of human health and the
 environment,  complies  with federal and state requirements that
 were  identified in the ROD as applicable  or relevant  and
 appropriate to this remedial action,  and  is cost-effective.  In
 addition,  the remedy continues to utilize permanent solutions and
 alternative treatment  technologies to the maximum extent
 possible,  as described in more detail in  the Declaration  of the
 Record of  Decision,  page v.
       ^
 Randall  F".' Smith
 Director,   Office  of  Environmental  Cleanup

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Citizens for a Healthy Bay
771 Broadway

Pacific Lutheran University Library
121st and South Park Avenue

In Rustorr

Ruston Town Hall
5117 Winnifred

In Olympia:

Washington Department of Ecology
300 Desmond Drive SE

In Seattle:

Environmental Protection Agency
1200 Sixth Avenue
                                    Questions?

   If you have questions or would like more information, please feel free to contact one of
   the following EPA representatives toll free in Seattle at 1 (800)424-4EPA, or as indicated
   below:

                                Piper Peterson Lee
                                  Project Manager
                                  (206)553-4951

                                  Jeanne O'DeU
                          Community Relations Coordinator
                                  (206)553-6919

   For those with impaired hearing or speech, please contact EPA's telecommunication
   device for the deaf ODD)  at (206)553-1698.

   To ensure effective communication with everyone, additional  services can be made
   available to persons with  disabilities by contacting one of the numbers listed above.
o

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                          N
   N. 51st. St.
       Arsenic,
       Kitchen
       Area

     RUSTON
                     Proposed
                     OCF
                     Location
Asarco
Smelter
Site
 \
Proposed QCF Location

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&EFA
    United States                         Region 10 (HW-117)
    Environmental Protection      .             1200 Sixth Avenue
    Agency                             Seattle WA 98101
Superfund Fact Sheet
Former Asarco Smelter Site

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                                   Region 10
                                   1200 Sixth Avenue
                                   Seattle WA 98101
                             Alaska
                             Idaho
                             Oregon
                             Washington
                                                                  September 20, 1995
 Superfund Fact Sheet

 Former Asarco Smelter Site
 Ruston and  Tacoma, Washington
 Update on Negotiations Between the U.S. Environmental Protection Agency (EPA) and Asarco
 on the Former Smelter Site
 EPA and Asarco began negotiations on the
 cleanup plan in August 1995. The plan
 includes cleaning up contaminated soil,
 slag, and surface water, including disposal
 of highly contaminated soil, without
 treatment, in an on-site containment
 facility (OCF) on the former Asarco Smelter
 site.

 One requirement for constructing the OCF
 was to determine that it was safe in the
 event of an earthquake. Seismic test
 results revealed that the location identified
 is not safe and another location  must be
 found. The current plan would put the
 OCF on top of an ancient riverbed filled
 with sands, silt, clay, peat and slag.
 Settling could cause the OCF to  sink,
 damaging the liners and the safety
 detection measures. And In a severe
 earthquake, the ground under the OCF
 could liquify, settle and shift, causing
 severe damage to the structure.

 Asarco is currently evaluating alternate
 locations for the OCF. Asarco is collecting
 information about the ground beneath the
 parking lot area to determine whether It
 would be a suitable location.  If it is not
 other areas will be evaluated.

 EPA will be taking comments through
 October 20, 1995, on any concerns or
 questions you may have about moving the
OCF.  Please send your comments to Piper
Peterson Lee. EPA Remedial Project
Manager, 1200  Sixth Avenue - MS/HW-
 113. Seattle. Washington 98101.
 Changing the OCF location may open up
 some interesting new public benefits
 without compromising the master land use
 plan that the public helped develop during
 the Asarco Weeks held in 1994. An Asarco
 Week will be held  in mid-October to discuss
 the changes and get public comment.
 Asarco will notify community members of
 that meeting.

 More Information

 The Remedial Design Reports (RDRs) that
 Asarco is submitting to EPA are being
 added to the information repositories for
 your review and comment. The first and
 second batch of RDRs are available.  The
 third batch, entitled infrastructure and
 transportation, will be available on
 September 27th. It describes the process
 to determine how the utilities, roadways,
 and other elements of future land use will
 be tied into the cleanup activities.  It also
 describes the process to determine the
 timing of road closures and other
 transportation issues.

What's Next

EPA and Asarco will complete negotiations
that includes an alternate location for the
OCF.  Once an agreement on the proposed
Consent Decree and Statement of Work
have been reached, another 30-day public
comment period will be offered.

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                                     Questions?

 If you have questions or would like more information, please feel free to contact one of the
 following EPA representatives toll free In Seattle at 1(800)424-4EPA, or as indicated below:

                                  Piper Peterson Lee
                                    Project Manager
                                    (206)553-4951

                                    Jeanne O'Oett
                           Community Relations Coordinator
                                    (206)553-6919

 For those with impaired hearing or speech, please contact EPA's telecommunication device
 for the deaf fTDD) at (206)553-1698.

To ensure effective communication with everyone, additional services can be made available
to persons  with disabilities by contacting one of the numbers listed above.

    United States
    Environmental Protection
    Agency
Region 10 (HW-117)
1200 Sixth Avenue
Seattle WA 98101
Superfund Fact Sheet
Former Asarco Smelter Site

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