PB97-964015
                                EPA/541/R-97/066
                                June 1998
EPA Superfund
      Record of Decision:
       Oak Ridge Reservation (USDOE)
       (Sludge Removal from the Gunite &
       Associated Tanks Operable Unit,
       Waste Area Grouping 1)
       Oak Ridge, TN
       9/2/1997

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                                  DOE/OR/02-1591&D2

    Record of Decision for Interim Action:
Sludge Removal from the Gunite and Associated
Tanks Operable Unit, Waste Area Grouping 1,
       Oak Ridge National Laboratory,
            Oak Ridge, Tennessee


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                                        DOE/OR/02-1591&D2
     Record of Decision for Interim Action:
Sludge Removal from the Gunite and Associated
 Tanks Operable Unit, Waste Area Grouping 1,
        Oak Ridge National Laboratory,
            Oak Ridge, Tennessee
             Date Issued—August 1997
                   Prepared by
                 Jacobs EM Team
                125 Broadway Avenue
                Oak Ridge, Tennessee
          under contract DE-AC05-93OR22028

                   Prepared for
              U.S. Department of Energy
          Office of Environmental Management

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                          PREFACE
This Record of Decision for Interim Action:   Sludge Removal from
the Gunite  and  Associated  Tanks  Operable  Unit,   Waste  Area
Grouping 1, Oak Ridge National Laboratory,  Oak  Ridge, Tennessee
(DOE/OR/02-1591&D2) was prepared in accordance  with requirements
under the Comprehensive Environmental Response, Compensation, and
Liability Act of 1980 and documents selection of the interim action.
This  work  was   performed  under  Work  Breakdown  Structure
1.4.12.6.1.01.41.19.18 (Activity Data Sheet 3300, "ORNL WAG 1
Treatability Studies").  This document identifies sludge removal as the
selected interim action for the Gunite and  Associated Tanks Operable
Unit.   This document  summarizes  information  from the feasibility
study/proposed plan (DOE/OR/02-1509/V1&D2, and V2&D2).

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                   ACRONYMS AND ABBREVIATIONS
ARAR
bgs
BVEST
CERCLA

CFR
Ci
Cs
CY
DOE
EPA
ER
FFA
FS
ft
FY
GAAT
gal
kg
km
L
Ib
LLW
LSS
m
MVST
NCP
NTF
NTS
OHF
ORNL
ORR
OU
PP
Pu
RME
ROD
Sr
STF
STP
TDEC
Th
TRU
U
applicable or relevant and appropriate requirement
below ground surface
Bethel Valley Evaporator Service Tanks
Comprehensive Environmental Response, Compensation, and Liability
Act of 1980
Code of Federal Regulations
curie
cesium
calendar year
U.S. Department of Energy
U.S. Environmental Protection Agency
environmental restoration
Federal Facility  Agreement
feasibility study
foot
fiscal year
Gunite and Associated Tanks
gallon
kilogram
kilometer
liter
pound
low-level (radioactive) waste
laboratory shift superintendent
meter
Melton Valley Storage Tanks
National Oil  and Hazardous Substances Pollution Contingency Plan
North Tank Farm
Nevada Test  Site
Old Hydrofracture Facility
Oak Ridge National Laboratory
Oak Ridge Reservation
operable unit
proposed plan
plutonium
reasonable maximum exposure
record of decision
strontium
South Tank Farm
site treatment plan
Tennessee Department of Environment  and Conservation
thorium
transuranic
uranium
JT00589703.IWR/CJE
                                        111
                                                                          August 25. 1997

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            ACRONYMS AND ABBREVIATIONS (continued)

WAG               waste area grouping
WIPP               Waste Isolation Pilot Plant
nX»589703.IWR/aE                          IV                             Augua 25. 1997

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                       PARTI.  DECLARATION
/T00589703.1WR/CJE                                                      Auguu 25, 1997

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       STUDY AREA/OPERABLE UNIT NAME AND LOCATION

      U.S. Department of Energy
      Oak Ridge Reservation
      Waste Area Grouping 1
      Gunite and Associated Tanks Operable Unit at the Oak Ridge National Laboratory
      Oak Ridge, Tennessee


                  STATEMENT OF BASIS AND PURPOSE

      This record of decision (ROD) presents the selected interim remedial action for removing
mixed transuranic (TRU) waste sludge from eight tanks  in the Gunite and Associated Tanks
(GAAT) Operable Unit (OU). The tanks are located in Oak Ridge National Laboratory (ORNL)
Waste Area Grouping  (WAG) 1.  The U.S. Department of Energy (DOE) has assigned a high
priority to the remediation of this  OU because of its high contaminant inventory and the age of
the tanks.  The objective of this interim action is to reduce the potential for on- and off-site risk
from the tank contents.

      The interim  action was  chosen  in accordance  with the  Comprehensive Environmental
Response, Compensation, and Liability Act of 1980 (CERCLA), as amended by the Superfund
Amendments and Reauthorization  Act of 1986 (42 United States Code, Sect. 9601 et seq.) and,
to the extent practicable, the National Oil and Hazardous Substances Pollution Contingency Plan
(NCP) [40 Code of Federal Regulations (CFR) 300].  The ROD is based on  the Administrative
Record for this site.

      DOE issues this document as the lead agency for environmental restoration (ER) activities
on ORR.  The U.S.  Environmental Protection Agency (EPA) and the Tennessee Department of
Environment and Conservation (TDEC) are supportive  agencies as parties to the Federal Facility
Agreement (FFA) for  this response action. They concur with the selected remedy.


                ASSESSMENT OF THE  STUDY AREA/OU

      A baseline risk assessment was conducted  to  determine whether remedial actions are
necessary  to protect human health and the environment if current institutional controls are
removed.  The scenarios considered include (1) dome failure  resulting in  direct  exposure to
workers and on-site residents and (2)  failure of the  tank shell resulting in contamination of

JT00589703.IWR/CJE                            1-2                               August 25. 1997

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groundwater with the associated pathway to a resident of nearby White Oak Creek. The risk
assessment clearly demonstrates that without  institutional controls the GAAT tanks pose an
unacceptable risk to human health and the environment now and in the future.  Thus, a remedial
action is required to address the GAAT OU.  The objective of this interim action is to reduce the
potential for on- and off-site risk from the tank contents.

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


                  DESCRIPTION OF SELECTED REMEDY

       The selected  interim remedial action includes removal  of the sludge and  subsequent
transfer to the Melton Valley Storage Tanks (MVST). The plans for removing GAAT sludge will
be included in  the remedial design and remedial action documentation.  However, the basic
equipment and  methodology are being demonstrated in an ongoing treatability study and have
been  successfully demonstrated in a test facility.  The most likely approach uses  a remotely
controlled arm  and vehicle combination to complete the sludge removal.  High-pressure water
jet equipment attached to the arm or vehicle will remove sludge from the walls and floors and
pump it out of the tank.   Where disposal options are available, equipment and debris will be
removed from the tanks, packaged, and disposed.  Any remaining debris will be rinsed, sampled,
placed into retrievable containers, and positioned in the tanks for later retrieval and disposition.
The slurried waste from  the tanks will be pumped to a consolidation tank and conditioned as
necessary (i.e., adjustment of water content  or particle size) to facilitate pumping this material
through existing transfer  lines to  MVST.   All  MVST wastes  will be prepared for eventual
disposal in another action.

       The selected remedy was developed considering the TRU waste strategy [i.e., consolidate,
treat, and ship waste to the Waste  Isolation Pilot Plant (WIPP) or the Nevada Test Site (NTS)]
and the strategy to evaluate residual contamination in the OU after waste removal  as part of the
Bethel Valley Watershed remediation.  After removal  of sludge, samples of the tank shell will
be collected to provide contaminant levels for consideration during future closure evaluations, as
part of the  Bethel Valley Watershed remediation.
rr
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                      STATUTORY DETERMINATIONS

        This interim action protects human health and the environment, complies with federal
and state applicable or relevant and appropriate requirements (ARARs) directly associated with
this action, and is cost-effective.  This action uses permanent solutions and alternative treatment
(or resource  recovery) technologies to the maximum extent practicable, given the limited scope
of the  action.  This action does not constitute the final remedy for the OU; therefore, the
statutory preference for remedies that employ treatment  for reduction of toxicity, mobility, or
volume as a principal element will not be satisfied by this interim action.  Treatment of the
MVST waste, including the GAAT sludge, will be performed as part of another action.  This
interim action addresses the principal threat  posed by this OU and ensures that the liquid and
sludge  will not increase future groundwater contamination.  Removal of the wastes will permit
the remaining structures (i.e., tanks, piping, and associated equipment) to be included in a later
sitewide action.  Because this is an interim action ROD, review of this site and of this remedy
will continue as DOE develops final remedial alternatives for  this OU and the overall site.
JT00589TO3.IWR/CJE                               1-4                                 Auguu 25. IW7

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                                  APPROVALS
 Rodney R. Nelson, Assistant Manager
 U.S. Department of Energy
 Oak Ridge Operations
                                                            / "2. I
             Date
 Earl C. Leming, Director^—-
             Date
 U.S. Department of Energy Oversight Division
 Tennessee Department of Environment and Conservation
 Richard D. Green, Acting Director
 Waste Management Division
 U.S. Environmental  Protection Agency, Region 4
             Date
JTOOS89703.IWR/CJE
1-5
                                                                          August 25. 1997

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                     PART 2.  DECISION SUMMARY
JT00589703.IWR/CIE                                                           August 25. 1997

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                            DECISION OVERVIEW

      This ROD describes the interim remedial action decision for the GAAT OU.  The GAAT
OU comprises 16 tanks located in or near the North and South Tank Farms at ORNL WAG 1,
Oak Ridge Reservation (ORR), Oak Ridge, Tennessee. DOE assigned remediation of these tanks
a high priority because of the high contaminant inventory and the age of the tanks.  The GAAT
OU includes  the tanks, residual waste materials  in the tanks,  and the operating equipment
associated with the  tanks.  A baseline  risk assessment was conducted to determine  whether
current or future remedial actions are necessary to  protect human health and the environment if
existing institutional controls are removed. The risk assessment clearly demonstrates that without
institutional controls the tanks pose an unacceptable risk to human health and the environment
both now and in the future.  Therefore, a remedial  action is required to address the GAAT OU.
The objective of this interim action is to reduce  the potential for on- and off-site risk from the
tank contents.

      The interim action proposed in this ROD is removal of liquid and sludge wastes from eight
tanks (W-3 through W-10) and transfer of the wastes to MVST.  Seven other tanks (W-l, W-la,
W-2, W-l 1, W-13, W-14, and W-15) in the GAAT OU contain no recoverable sludge, have low
contaminant levels, and do not pose a significant threat to human health or the environment either
now or in the future. Tank TH-4 is also part of the GAAT OU and contains sludge; however,
its contents are very different  from the contents of the other sludge-containing tanks and do not
pose a significant threat to human health and the environment. DOE is deferring action on the
contents of these eight tanks (seven nonsludge-bearing tanks plus Tank TH-4) and any residual
contamination left in Tanks W-3 through W-10 after waste removal.  At that time, the  need for
any further remedial action will be evaluated as part of the Bethel Valley Watershed remediation
decision process.

      The Gunite tanks were originally constructed in the 1940s with a projected operational life
of 1 year.  Although monitoring data have not indicated that any tanks are leaking, remote visual
inspections of the tanks  have revealed some degradation on the interior surface of Tanks W-5 and
W-6.  The results of these inspections and the age  of the tanks have raised concerns about their
long-term integrity.  Liquid  and solid  materials stored  in the  tanks include mixed  wastes
containing radionuclides, organics in trace amounts, and heavy metals. Solids in some of the
tanks contain U, Pu, Th, and other long-lived (thousands of years) isotopes that meet the criteria
for TRU waste. These wastes also  contain high concentrations  of l37Cs  and ^Sr, which have
relatively short half-lives (approximately 30 years), in addition to other radionuclides with half-
JT0058970J.IWR/CJE                              2-2                                 AugusJ 25. 1997

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lives of a few days.  The high radiation levels in the tanks will require "remote operation" to
control exposures to workers performing the waste removal operations.

      Approximately 1.32 million L (350,000 gal) of liquid and 189,000 L (50,000 gal) of
sludge remain in the tanks.  The estimated radionuclide inventory ranges from 40,000 Ci, based
on the most recent analytical results, to over  100,000 Ci, based on previous estimates for the
eight tanks  addressed by this interim action.

      DOE evaluations of cleanup options for the Gunite tanks indicate that the best current
action is to remove the tank liquid and sludge wastes, which could be released easily by a tank
failure, and transfer these wastes to a'permitted storage facility.  Treatment will occur as part of
another  action.   The  decision to remove these wastes from the  Gunite tanks was  made
concurrently  with the need to  manage similar wastes located in other  tanks at  ORNL.  DOE
manages an inventory of more  than 757,000 L (200,000 gal) of TRU waste at ORNL facilities,
including GAAT, MVST, the  Bethel Valley Evaporator Service Tanks (BVEST), and the Old
Hydrofracture Facility (OHF). As part of a separate, nationwide effort, DOE  is procuring
services to  treat and dispose of this inventory at WIPP and NTS (DOE 1996a).   The activities
at ORNL are also being conducted in compliance with the TDEC Commissioner's Order on the
site treatment plan (STP).  Treatment and shipment of ORNL wastes are scheduled to coincide
with the window for receiving remote-handled TRU waste at WIPP, starting near the end of fiscal
year (FY) 2002. This limited window places a high priority on completing waste accumulation
and treatment activities at ORNL.

      To support efficient treatment, DOE plans to accumulate all TRU tank waste, including
the Gunite  tank wastes, at MVST.  This will allow the treatment contractor sufficient time to
mobilize, build needed facilities, and begin treating and shipping the wastes to WIPP or NTS by
the end of FY 2002.  MVST is comprised of eight, approximately 50,000 gal  underground
storage  tanks  within a stainless-steel-lined concrete vault.   These tanks meet  FFA  specified
secondary  containment standards and are  part of the permitted National  Pollutant Discharge
Elimination System.  These tanks are currently in use and contain TRU waste  from previous
process  and restoration activities.

      MVST's capacity to receive wastes is limited until an ongoing project that will add six
new tanks  to the MVST is completed in late calendar year (CY) 1998.  DOE has developed a
strategy  that allows all three  of the  waste removal projects (GAAT,  BVEST, and  OHF) to
proceed in  parallel and meet the goal of accumulating the TRU tank waste at MVST by the end
of FY 2000.  This strategy calls for the transfer of BVEST and OHF waste to MVST from late
CY 1997 to early CY 1999. During this period, DOE plans to use one or two  of the existing

JTOOS89703.IWR/CIE                              2-3                                August 25, 1997

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Gunite tanks to temporarily hold, or "consolidate," the wastes  that will be produced by the
GAAT interim action.  This will allow several of the Gunite tanks to be cleaned while wastes
from BVEST and OHF are being transferred to MVST. The wastes are scheduled to be removed
from  the  consolidation tanks and transferred to  MVST starting in early CY 1999.   The
consolidation tanks will be emptied by March 2001.

       DOE has thoroughly investigated the integrity of the Gunite tanks and has selected Tank
W-9 to be the primary consolidation tank.  DOE selected W-8 to be the backup consolidation
tank.  Analysis of the structural integrity of these two tanks indicates they are sound, and analysis
of internal liquid level data from the tanks indicates  that W-8 and W-9 are liquid tight within the
statistical uncertainties inherent in the analysis (ORNL 1997a).  In addition to these analyses, the
electrical conductivity of the groundwater is being  monitored in the dry wells associated with each
of the tanks.  This method can easily detect releases from the  Gunite tanks on the order of
0.5 gal/hour.   The  method  has  been thoroughly  evaluated by conducting  simulated (high
conductivity) liquid release tests on the Gunite tanks in the North Tank Farm (NTF) and South
Tank Farm (STF).  Testing has been successfully  completed in the NTF (ORNL  1997a), and
testing of the method for Tank W-9 in the STF was  recently completed (ORNL 1997b).  Testing
is in progress for Tank W-8  and other STF tanks.  Results will be represented in subsequent
reports. The dry well conductivity monitoring  method is being used to provide rapid real time
release detection for Tanks W-3 and W-4 in the NTF and will  be used for real time release
detection for the consolidation tanks in the STF.

       The  overall  responsibility  for  responding  to emergencies  at  ORNL rests  with the
laboratory shift superintendent  (LSS).  The office of the LSS  is housed  in the  Laboratory
Emergency Response Center which has the responsibility, personnel, and equipment to respond
around-the-clock.  The GAAT Spill/Leak Response Plan was developed in coordination and in
conjunction  with the LSS and describes actions to  be taken in the event of a  release from the
tanks.

       The GAAT Remediation Project has a trailer-mounted Moyno  pump, hoses and fittings,
absorbent, and storm drain covers at its disposal.  Covers will be placed over selected storm
drains and surrounded with absorbent, placed prior to  transfers between tanks.  Project and
selected support personnel will perform drills with the Spill/Leak Response Plan in coordination
with the LSS on an annual  basis.  Spills and  leaks will be pumped into the active waste
management system or into a  sound Gunite tank as  conditions warrant. The  LSS will assist the
GAAT Project in responding  to any situations that  require additional personnel and equipment.
JT00589703.1WR/CJE                              2-4                                 Augusi 25. 1997

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       DOE  believes that  any inefficiencies involved in double-handling the waste in the
consolidation process are outweighed by several important benefits.

       The consolidation process provides the capability to even out the flow from the waste
removal equipment and accumulate large enough batches of waste for efficient transfer to MVST.
Excess water generated during the waste removal process can be extracted  and sent to BVEST
for concentration, thereby minimizing the liquids generated during Gunite tank waste removal and
managing utilization of the limited space available at MVST. Most importantly, the consolidation
approach will facilitate the  eventual transfer of the waste to MVST.  Waste removed from the
Gunite tanks  must be "conditioned" (particle  size and water content adjusted) before it can be
transferred to MVST through the mile-long pipeline between Bethel Valley  and Melton Valley.
DOE plans to install a conditioning system in  the consolidation tanks similar to that used in the
1982 waste removal  campaign that successfully avoided plugging the  only route  for transfer of
radioactive liquid waste from the main plant of ORNL to MVST (ORNL 1984).

       A CERCLA treatability study was initiated to determine the  effectiveness  and cost of
technologies that could remove liquid and sludge wastes from the GAAT. A phased program was
developed to minimize risks to workers and the public during remediation. This program started
with "cold tests" that were designed to ensure  the proper operation of waste  removal equipment.
The  cold tests, completed  in May  1997, demonstrated that the equipment is able to remove
surrogate  waste from a simulated  tank as well  as clean waste from the interior surface of a
simulated tank shell. "Hot tests" with the lower contaminant concentration wastes in Tanks W-3
and W-4 will be performed in the summer and fall of 1997; these tests are  designed to confirm
that the waste removal equipment operates safely and effectively for actual radioactive tank waste.
This demonstration will increase confidence in the waste removal equipment's ability  to safely
remove the much more radioactive wastes from Tanks W-5 through W-10 and will help define
how much waste can be removed from the tanks.

       When waste  removal operations  in this interim  action are  complete,  contamination
remaining in the tanks will be limited to small  quantities of sludge,  contaminants in the tank
shells, and contaminated debris (equipment, rocks, plastic, and Gunite pieces) collected during
the cleaning operation. Some residual liquid  and sludge is likely to remain in pockets and low
points.   A total  of  approximately  229 m (750  ft)  of small diameter process  piping with a
combined volume of approximately  1.3 m3 (45 ft3)  will remain embedded in the  concrete or
attached to walls of the tanks.  The amount of contamination remaining in  the tank shells after
waste removal  will be determined  through a  combination of in situ measurements and sample
analysis.  Solid debris collected to facilitate  sludge removal  will be packaged for subsequent
characterization and  disposal in accordance with available disposal options.

JT00589703.1WR/CJE                              2-5                                 Augusi 25. 1997

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      Approximately 16.8 m3 (600 ft3) of wiring, piping, and other debris have been removed
from these tanks to provide access for waste removal equipment.   Approximately  13,608 kg
(30,000  Ib) of surface equipment has been removed and recycled, and 33.6 m3 (1,200 ft3) of
contaminated  LLW material was removed and shipped to an off-site contractor for disposal.
Disposal or remediation of any remaining equipment and debris collected during waste removal,
as well as potentially contaminated soils and tank appurtenances external to the tank shells, will
ultimately be  evaluated as part of the Bethel Valley watershed remediation decision process.
Approximately 16.8 m3 (600 ft3) of mixed wastes are currently held in a process pit in the STF
and remain candidates for later waste consolidation.  Moving this material as part of this interim
action is impractical because no better defined or permitted facilities are available locally for this
class of  wastes.


              SITE NAME, LOCATION, AND DESCRIPTION

      The  GAAT OU  is  located within ORNL  on the  DOE ORR, approximately 24 km
(15  miles)  west  of Knoxville,  Tennessee, and 16 km (10 miles) southwest of the Oak Ridge,
Tennessee, business center (Fig. 2.1). The ORNL main plant area is located in Roane County
adjacent to Bethel Valley Road, approximately 2.5 km (1.5 miles) east of the intersection with
State Highway 95.

      In the 1940s, DOE placed in service 12 Gunite tanks as part of the liquid waste treatment
system.  Four smaller, steel tanks were constructed in the  late 1940s and early  1950s.  All 16
tanks are located underground in the main plant area.  Eight of these tanks (W-3 through W-10)
are  located at  the intersection of Central Avenue and Third Street in the North and South Tank
Farms and are included in the scope of this interim action ROD.

           SITE HISTORY AND ENFORCEMENT ACTIVITIES

      ORNL, one of three major plants on ORR,  opened  in 1943 as the Clinton  Laboratories
to support defense activities for the Manhattan Project.  It evolved into a premier research facility
with a diverse range of programs. On November 21, 1989,  EPA placed ORR on the National
Priorities List under CERCLA. On January 1, 1992, DOE, EPA,  and TDEC entered into an
FFA to provide a procedural framework and schedule for evaluating, prioritizing, and managing
ER activities on ORR. The agreement also specifies that CERCLA procedures will be followed
to evaluate and remediate contamination problems.
mXK89703.IWR/aE                             2-6                                August 25, 1997

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                                                                                    ORNL  Main Plant Area    ,.,„.,..... „„.
          NOT TO SCALE
JE
Fig.  2.1
Location of  ORNL  and  the  North  and  South Tank  Farms
    DOE  -  ORNl. WAG 1 Gunite  and Assooaied Tanks  •  Oak Ridge. Tennessee
DOCUMENT 10 35M830
0058-05 / PS PP
                                                                                                          96-1?928DWC
DRAWING DATE
16 Juni 97. WiM

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      The Gunite tanks were originally constructed in the 1940s with a projected operational life
of 1  year.  Mixed-TRU waste generated by operations of ORNL's processing and research
facilities was stored in a network of underground tanks as part of the Manhattan Project. The
tanks were removed from service beginning in the 1950s, with all tanks out of service by the
1970s.  Most of the liquid and sludge waste was removed  from the tanks between 1982 and 1984,
and staged temporarily in the MVST.  Waste was mixed with grout and injected into a deep shale
formation.

      A more detailed discussion of the remaining tank contents and characteristics is presented
in the remedial investigation/baseline risk assessment for the GAAT OU (DOE 1994) and the
addendum to that report (DOE 1996b). These and other documents are available as part of the
Administrative Record.  A treatability study associated with this action is currently underway.
The feasibility study (FS)/proposed plan (PP) evaluated potential  interim actions in accordance
with the requirements of CERCLA and the NCP, presented DOE's determination that liquid and
sludge  removal  is  necessary in eight of the tanks, and solicited public comment on the
determination (DOE 1997).  Part 3 of this ROD documents public comments on the FS/PP and
DOE's response to those comments.

            HIGHLIGHTS OF COMMUNITY PARTICIPATION

      The FS/PP for the GAAT OU was released to the public May 2, 1997.  This document
is part  of the Administrative Record  for the OU and is maintained at the DOE Information
Resource Center, 105 Broadway Avenue, Oak Ridge, Tennessee.  The notice of availability for
this plan and other documents in the Administrative Record was published in The Knoxville News-
Sentinel May 2, 1997, The Oak Ridger May 1, 1997, and The Roane County News May 2, 1997.
A public meeting to discuss the FS/PP was held June 2, 1997.  A public comment period
scheduled for May 2,  1997, through June 2, 1997, was extended to June 13, 1997.  Oral and
written comments received from three members of the public are  responded to in Part 3 of this
ROD.


       SCOPE AND ROLE OF OU AND THE REMEDIAL  ACTION

      Under CERCLA, an OU is a discrete area that is part of a larger area or response action.
At ORNL, WAG 1 was divided into separate OUs.   GAAT, an OU within WAG 1, comprises
16 tanks located in or near the North and South  Tank Farms at ORNL.  DOE assigned
remediation of these tanks a high priority because of the high contaminant inventory and the age

JT00589703.1WR/CJE                            2-8                               August IS. !W

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of the tanks.  The GAAT OU includes the tanks, residual waste materials in the tanks, and the
operating equipment associated with the tanks. For purposes of this action, all the tanks and their
contents are being considered as one area of contamination.

      To support efficient treatment, DOE plans to accumulate all TRU tank waste, including
the Gunite tank wastes, at MVST.  This will allow the treatment contractor sufficient time to
mobilize, build needed facilities, and begin treating and shipping the wastes to WIPP or NTS by
the end of FY 2002.  MVST's capacity to receive wastes is limited until an ongoing project that
will add six new tanks to MVST is completed in late CY 1998.  DOE has developed a strategy
that allows all three of the waste removal projects (GAAT, BVEST, and OHF) to proceed in
parallel and meet the goal of accumulating the TRU tank waste at MVST. This strategy calls for
the transfer of BVEST and OHF waste to MVST from late  CY 1997 to early CY 1999.  During
this period, DOE plans to use one or two of the existing Gunite tanks to temporarily hold, or
"consolidate," the wastes that will be produced by the GAAT interim action.  This will allow
several of the Gunite tanks to be cleaned while  wastes  from  BVEST and OHF  are being
transferred to MVST.  The wastes are scheduled to be removed from the consolidation tanks and
transferred to MVST starting in early CY 1999.  The consolidation tanks will be emptied by
March 2001.

      The scope of this interim remedial action for the GAAT OU is limited to the contents of
Tanks W-3 through W-10.  Discussions of groundwater and surface water were included in this
ROD only to  identify potential sources of contamination and receptor pathways.  Removal of the
liquid and sludge  waste substantially  reduces  any future  risk of release or exposure.   The
remaining tank contamination (and the surrounding tank farm areas) will be evaluated as part of
the Bethel Valley Watershed remediation decision process.  Appropriate follow-on actions will
be conducted at a later date if necessary. The  selected interim remedy  does not  preclude any
future remedial actions at the site that may be implemented.


                 SUMMARY OF SITE  CHARACTERISTICS

       Liquid and  solid  materials stored  in  the  tanks  include mixed  wastes  containing
radionuclides, organics in trace amounts, and heavy metals. Solids in some of the  tanks contain
U, Pu, Th, and other long-lived (thousands of years)  isotopes that meet the criteria for TRU
waste. These wastes also contain high  concentrations  of l37Cs and ^Sr, which have relatively
short half-lives (approximately 30 years), in addition to other radionuclides with half-lives of a
few days.  The high radiation levels in the tanks will require "remote operation"  to control
exposures to  workers performing the waste removal operations.

JTD0589703.IWR/CJE                             2-9                                August 15. 1997

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       Approximately 1.32 million L (350,000 gal) of liquid and 189,000 L (50,000 gal) of
sludge remains in the tanks. The estimated radionuclide inventory ranges from 40,000 Ci, based
on the most recent analytical  results, to over 100,000 Ci,  based on previous estimates for the
eight tanks addressed by this interim action.


                          SUMMARY OF SITE RISKS

       DOE enforces strict institutional controls  at the GAAT OU to  mitigate uncontrolled
exposures because of contaminants in the tanks. Institutional controls, along with administrative
controls, comply with regulatory limits for exposures to on-site workers and visitors, minimize
chances for direct contact with the tank contents, and ensure that off-site receptors are protected
if a tank leaks.  An evaluation of tank level monitoring data indicates the tanks are not currently
leaking.  The North and South Tank Farms each include a groundwater  collection system that
lowers the ambient groundwater below the base of the tanks and directs the collected groundwater
to a pump station for transfer to the Process Waste Treatment Plant, where low  concentrations
of radionuclides are reduced to a level that meets the requirements  of DOE Order  5400.5,
"Radiation Protection of the Public and the Environment."

       A baseline risk assessment (DOE  1994 and 1996b) was conducted to determine and
document the risk levels if institutional controls are removed.  The evaluation was based  on Tank
W-10 because this tank contains the highest radionuclide volume and  concentrations for those
tanks  that contain sludge. The pathways of concern are direct radiation exposure in the  event of
a dome collapse and  ingestion of contaminated drinking water by future residents. The source
release/groundwater  transport model  assumed that the  tank  shell  immediately  failed and
contaminants of concern  in the liquid  and sludge (primarily ^Sr and 137Cs) were released or
leached  into  groundwater.    The contaminated  groundwater was  assumed  to  follow  a
nondispersive, direct path into White Oak Creek at a point approximately 370 m (1,200 ft) south
of the NTF.

HUMAN HEALTH RISKS

       The human health risks reported in the baseline risk assessment (DOE 1994) considered
current and future scenarios for potential impacts of a tank dome collapse and failure of a tank
shell.   For the current use scenario, there is no evidence of contaminant release from the tanks
to  a pathway for an off-site  receptor.  The existing  institutional controls adequately protect
workers by limiting access to the site and monitoring exposure.
JT00589703.IWR/CJE                              2-10                                August 25, 1997

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       For the future use scenario, risks to an on-site resident, an employee, a nearby resident,
and a child wading in White Oak Creek were considered.  The EPA risk value of concern is
1 x  10^* or greater, which was exceeded for all but the last of the following:

       •  For an on-site resident, the greatest potential risk comes from direct radiation that
          might be released if the tank dome collapsed.  The total risk from all pathways is
          6  x  10'  for the  reasonable maximum exposure (RME) and 9 x 102 for the mean
          exposure.

       •  The potential risk to  an employee from direct exposure associated with  tank dome
          collapse could reach 9 x 102 for the RME and 1 x  10"2 for the mean exposure.

       •  For a nearby resident, ingestion of contaminated drinking water from White  Oak
          Creek poses the greatest risk.  The total risk is  1 x  103 for the RME and 3 x KT4
          for the mean exposure.

       •  The calculated risk for a child wading in White Oak Creek (4 x 10 6 for the RME and
          1  x  10"7 mean exposure) does not  exceed the EPA target risk value of 1  x 10"*.

ENVIRONMENTAL HEALTH RISKS

       The GAAT  OU is located in a highly developed  industrial area with few ecological
receptors. Although the risk assessment for the GAAT OU did not calculate ecological effects
of this interim action, ecological issues will be addressed in a future sitewide study, as required
under the FFA.


                     DESCRIPTION OF ALTERNATIVES

       Although several alternatives were initially considered for a full range of remedial actions,
an agreement among  DOE, TDEC, and EPA for an interim action to remove only the  tank
contents eliminated from consideration all but one action alternative. Thus, the only alternatives
considered in the FS/PP were:

       •  Alternative 1—No Action
       •  Alternative 2—Sludge Removal
JTOOS89703.IWR/CJE                             2-11     •                           August 25. 1997

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ALTERNATIVE 1-NO ACTION

      The NCP requires inclusion of a no action alternative for use as a baseline in comparing
and considering  other remedial  alternatives.  The no action alternative assumes that  existing
institutional controls—such as monitoring, removing water from the tanks, and restricting access
to the tank farms—would be maintained 30 years.  No action would be taken to remediate the
tank shell.

      Without removal of the liquid and sludge, eventual release of the waste following  collapse
of the tank dome or  failure of the tank shell could endanger human health and the environment.
As indicated in the "Summary of Site Risks" portion of this ROD, the risk of direct exposure
could be as high as  6 x 10"' for a future on-site resident and as high as 9 x 10"2 for  a future
employee.  The risk  to a nearby resident from the ingestion of contaminated drinking water from
White Oak Creek could reach 1 x 103, but calculations indicate that the risk for a child wading
in the water would not exceed EPA's target value of 1  x 10"*.

ALTERNATIVE 2—REMOVAL/TRANSFER OF TANK CONTENTS TO MVST

      This alternative includes removal of the liquid and sludge and subsequent transfer to
MVST.  All MVST wastes will be prepared for eventual disposal in another action.  Sludge from
the GAAT OU would be included in that effort.

      The selected  interim alternative  will include removal  of the  liquid and  sludge  and
subsequent transfer to MVST. The approach for removing GAAT waste will be included in the
remedial design and remedial  action documentation.   However, the basic equipment  and
methodology being evaluated in the treatability study have been successfully demonstrated  in a
test facility.  The most likely  approach uses a remotely controlled arm and robotic vehicle
combination to complete the sludge removal.  High-pressure water jet equipment attached to the
arm or vehicle will remove waste from the walls and floors and pump it out of the tank.  Debris,
collected to facilitate sludge removal, will be rinsed, sampled, placed into retrievable containers,
and positioned in the tanks  for later retrieval  and disposition.   Waste will  be pumped to a
consolidation tank for conditioning (i.e., adjusting the water content, particle size) and transferred
by existing pipelines to MVST.

      DOE plans to transfer GAAT wastes to MVST as part of the ORNL TRU waste strategy.
The treatability study will determine technical limits of the remediation technology and establish
an initial goal for waste removal. DOE will attempt to dislodge and remove all sludge materials
from the tanks and  clean the walls and floor of each tank.  The ability of the waste  removal

JTOOS89703.IWR/CJE                             2-12                                 Auguu 25, 1997

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system to accomplish this  goal will not be completely known until the  project is actually
underway.  The FFA panics will determine when the waste removal system's practical limit has
been reached if the initial goal developed during the treatability  study  proves technically
impractical or cost-inefficient.  Results will be documented in a project completion report.

      DOE will maintain responsibility for treatment and final disposition of the GAAT wastes
after transfer to MVST, a permitted storage  facility for mixed waste  that contains wastes from
other OUs within the ER Program as well as non-ER wastes. Mixed wastes on ORR are being
managed  under  a  modified  STP  as  directed by  the  TDEC  Commissioner's  Order
(October 2, 1995) and as provided  for in Section 105 of the Federal Facilities Compliance
Agreement (January 1992).  The GAAT wastes, as pan of the MVST wastes, will be treated in
a permitted facility to meet all regulatory and DOE requirements as well as disposal facility waste
acceptance  criteria.  Final disposition of the wastes  will be  at  WIPP, NTS,  or  another
appropriately permitted facility.

      The GAAT OU is located in the ORNL historic district. DOE  Oak Ridge Operations and
the State Historic Preservation  Office signed a memorandum of agreement for the GAAT OU,
which the Advisory Council on Historic Preservation accepted January 31, 1995.  This agreement
ensures that the site's aesthetics will be  maintained to the extent  practicable for the duration of
the action.

      ARARs specific to Alternative 2  are listed in Table 2.1.


   SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES

      Of seven action alternatives originally conceived, only  one met the specifics of the
agreement among DOE, TDEC, and EPA to completely remove the sludge from the eight tanks.
This alternative and the mandated no action alternative were evaluated using the nine EPA criteria
(40 CFR 300.430).  Table  2.2 summarizes this evaluation.

      Alternative 2, removal and transfer of tank contents to MVST,  removes and safely stores
the contaminant source to prevent  exposure before final treatment and disposal, thus providing
both short- and long-term protection of human health and the environment.
/T00589703.IWR/CJE                             2-13                               A«g"* &. 1997

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             Table 2.1.  ARARs and TBC guidance for the preferred alternative for the GAAT Interim Remedial Action, WAG 1, ORNL,
                                                               Oak Ridge, Tennessee
i
m
        Resource/Action
Requirement
Prerequisite
Citation
                                   Location'Speciftc
        Presence of federally
        owned, administered,
        or controlled historic
        properties
Action(s) that will affect such resources must be
identified and alternatives to the action(s) examined and
considered

When alteration or destruction of the resource is
unavoidable, steps must be taken to minimize or
mitigate the impacts and to preserve records and data
of the resource

Steps must  be taken to consider the historical,
architectural, or archaeological significance of sites,
structures, and objects and to consult with the SHPO
Action which will impact
such resources-
applicable
National Historic Preservation
Act Sections 106 and 110
(16 USC 470 et seq.);
36 CFR 800;
EO 11593 (TBC only)
                                                                  Action-specific
       Control of fugitive
       dust
        Control of
        radionuclide
        emissions
Take reasonable precautions to prevent paniculate
matter from becoming airborne;  no visible emissions
are permitted beyond the property boundary lines for
more than 5 minute/hour or 20 minute/day

Exposures to  members of the public from all radiation
sources released into the atmosphere shall not exceed
an EDE of 10 mrem (0.1  mSv)/year


Radiological emission measurements required at all
release points that have a potential to discharge
radionuclides in quantities which could cause an  EDE
in excess of 1 % of the standard  (0.1 mrem/year)
Nonpoint source air
emissions from
construction/remediation
activities—applicable

Release of radionuclide
emissions to the air from
DOE facilities-
applicable
Rules of the TDEC 1200-3-8-
.010
40 CFR 61.92;
Rules of the TDEC 1200-3-
11-.08
                                                                                                               40CFR61.93(b)(4)(i);
                                                                                                               Rules of the TDEC  1200-3-

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                                                      Table 2.1.  (continued)
Resource/Action
Requirement
Prerequisite
Citation
Control of surface
water runoff

All radionuclides which could contribute greater than
10% of the standard (1 mrem/year) for a release point
shall be measured

Exposures to members of the public from all radiation
sources shall not cause an EDE to be  > 100 mrem
(1  mSv)/year

DOE will carry out all DOE activities to ensure that
radiation doses to individuals will be ALARA

Implement good site planning and best management
practices to control stormwater discharges, including:

•      document best management practices in a
       stormwater control plan or equivalent document

•      use minimal clearing for grading

•      remove vegetation cover only within 20 days of
       construction

•      perform weekly erosion control inspections and
       maintenance

•      implement control measures to detain runoff

•      prevent discharges from causing erosion
                                                                            Release of radionuclides
                                                                            into the environment—
                                                                            TBC
Stormwater discharges
associated with
construction activities at
industrial sites that result
in a disturbance of 5 acres
or greater of total land
area—relevant and
appropriate
                                                                                                       40CFR61.93(b)(4)(i);
                                                                                                       Rules of the TDEC 1200-3-
DOE Order 5400.5(11. la);
10CFR834.101 (proposed)


DOE Order 5400.5(1.4);
10 CFR 834 (proposed)

Rules of the TDEC 1200-4-
10-.05;
40 CFR 122

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                                                             Table 2.1. (continued)
        Resource/Action
                       Requirement
                                                     Prerequisite
                          Citation
I
m
Removal/transfer of
tank contents to
MVST system,
characterization and
disposal of treatment
residuals and
decontamination fluids
A person who generates solid waste must determine
whether that waste is hazardous using various methods,
including application of knowledge of the hazardous
characteristics of the waste based on information
regarding the materials or processes used

All tank systems, conveyance systems, or other
ancillary equipment (does not include containers) used
to transport RCRA-hazardous wastewater for treatment
are  exempt from RCRA Subtitle C requirements if the
wastewater is sent to an on-site wastewater treatment
facility subject to regulation under Sections 402 or
307(b) of the CWA (i.e.,  NPDES-permitted)

Management of TRU waste shall be conducted in such
a manner as to provide reasonable assurance that the
combined annual dose equivalent to any  member of the
public in the general environment resulting from
discharges of radioactive material  and direct radiation
from such  management shall not exceed 25 mrem/year
to the whole body and 75 mrem/year to any critical
organ

Must  meet waste acceptance criteria of receiving
facility for storage/disposal of LLW/TRU waste at
ORR
Generator of solid
waste—applicable
Rules of the TDEC 1200-1-
                                                                                   Storage/transfer of any
                                                                                   RCRA-hazardous
                                                                                   wastewater including
                                                                                   decontamination water-
                                                                                   applicable
                                                                                   Handling/management of
                                                                                   TRU waste—relevant and
                                                                                   appropriate"*
                                                                                                             40CFR262.il;
                                                                                                             40 CFR 268.7
                          40CFR260.10;
                          40CFR264.1(g)(6);
                          40CFR270.1(c)(2)(v);
                          Rules of the TDEC 1200-1-
                                                                                                      40 CFR 191.03(b)
                                                                                   Storage/disposal of any
                                                                                   LLW/TRU waste or
                                                                                   wastewater
                                                                                   generated-TBC
                                                                                                      DOE Order 5820.2A

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                                                                      Table 2.1.  (continued)
         Resource/Action
                            Requirement
                                                           iPrereqiciisltel
                              Citation
5
m
K)
  Institutional controls
  for contaminated
  tanks left in place
Controls include, but are not limited to: periodic
monitoring, as appropriate;  appropriate shielding;
physical barriers (i.e., fences, warning  signs) to
prevent  access; inspection and repair of coverings;
temporary dikes; drainage courses; appropriate
radiological safety measures to ensure protection during
activities at the site
Long-term management of
residual radioactive
material above guidelines
left in inaccessible
locations—TBC
                                                                                                                             DOE Order 5400.5 (IV.6c)
       "10 CFR 834.109 (proposed mle) requires (hat management of radioactive waste not exceed an EDE of 25 mrem/year from all pathways.  When promulgated, this rule will be legally
       applicable.
       'DOE Order 5400.5, Chapter Il.l(c)(l), requires thai TRU waste management and storage activities at facilities other than disposal facilities not cause members of the public to receive
       in a year a dose equivalent  >  25 mrem to the whole body or a committed dose equivalent > 75 mrem to any organ.
A LARA = as low as reasonably achievable
ARAR  = applicable or relevant and appropriate requirement
CFR = Code of Federal Regulations
CWA = Clean Water Act of 1972
DOE = U.S. Department of Energy
EDE = effective dose equivalent
EO = Executive Order
FR = Federal Register
>  = greater than
GAAT  = Gunite and Associated Tanks
LLW = low-level (radioactive) waste
mrem = millirem
mSv =  millisievert
                                                    MVST = Melton Valley Storage Tanks
                                                    NPDES = National Pollutant Discharge Elimination System
                                                    ORNL = Oak Ridge National Laboratory
                                                    ORR = Oak Ridge Reservation
                                                    % = percent
                                                    RCRA = Resource Conservation and Recovery Act of 1976
                                                    SHPO  = Stale Historic Preservation Office
                                                    TBC = to be considered
                                                    TDEC = Tennessee Department of Environment and Conservation
                                                    TRU = transuranic
                                                    USC = United States  Code
                                                    WAG = waste area grouping
.<*
1

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                               Table 2.2.  Summary of alternative evaluation,  GAAT OU, WAG 1, ORNL, Oak Ridge, Tennessee
                  CERCLA criteria
                                                      No action alternative
                                                                              Removal and storage
I
m
to
>—•
00
Protection of human health and the
environment

Compliance with ARARs

Long-term effectiveness and
permanence

Short-term effectiveness

Reduction of toxicity. mobility, or
volume through treatment
Implementability

Cost
         State acceptance
         Community acceptance
Poor. Tanks will eventually fail and release contents


Not applicable

Poor. Tanks will eventually fail and release contents


Fair.  Assuming tank failure is not imminent


Poor. Does not reduce toxicity, mobility, or volume
through treatment

Good.  Alternative is already in place
Good.  Removal and safe storage of sludge will remove major risk of
OU

Complies with all ARARs

Good.  Removes principal  threat from this OU


Moderate. Some risk associated with removal and transport of
radioactive sludges

Poor. Does not reduce toxicity, mobility, or volume through  treatment


Good.  Treatability study in progress will determine the most effective,
cost efficient design for removal devices
                                              Water removal with treatment, maintenance: $4.2 million     Total capital costs':  $35.1 million
                                     TDEC has expressed its desire that the waste be removed
                                     from the tanks
                                     No public support, through written comments or at the
                                     public meeting June 2, 1997, was received regarding this
                                     alternative.
                                                        Total postremoval operation and maintenance costs (5 years): $1.7 million

                                                        Total project present worth: $34.3 million

                                                        Regulators have reviewed and commented on documents during scheduled
                                                        review periods. Deadline for public comments on this document extended
                                                        from June 2, 1997, to June  13, 1997.  Stakeholders also participated in the
                                                        review of documents

                                                        Public comments and  DOE responses are summarized in Part 3 of this
                                                        document. At the June 2 meeting, the public strongly  supported removal
                                                        of the waste from these tanks.
        'Actual cost will vary depending on the results of the treatability study, subsequent waste transfer costs, and (he actual engineering options selected.  Regardless, DOE believes that this
        selected alternative will be a cost-effective remedy for removing GAAT sludge.
        ARAR = applicable or relevant and appropriate
         requirement
        CERCLA = Comprehensive Environmental  Response,
         Compensation, and Liability Act of 1980
        $ = dollar
        DOE =  U.S. Department of Energy
        GAAT = Gunite and Associated Tanks
                                                      ORNL  = Oak Ridge National Laboratory
                                                      OU = operable unit
                                                      WAG = waste area grouping

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                          THE SELECTED REMEDY

      This selected interim remedy complies with all ARARs.  Based on consideration of the
requirements of CERCLA, the detailed analysis of the alternatives using the nine criteria and
public comments, DOE, EPA, and TDEC have determined that the preferred alternative, removal
and transfer of tank contents to MVST, provides the most appropriate remedy for Tanks W-3
through W-10.  As described in Alternative 2, the liquid and sludge will be removed, the tank
walls and floors cleaned, and the resulting waste pumped to MVST.  Any remaining debris will
be sampled  and containerized for  future removal  if necessary.   The tank shells will be
characterized to support the Bethel Valley Watershed remediation decision process.

      DOE believes that this selected alternative will be a cost-effective remedy for removing
the GAAT sludge.  The unacceptable level of risk associated with tank failures will be reduced
or eliminated when the sludge in the tanks is removed.


                      STATUTORY DETERMINATIONS

         Section 121 of CERCLA requires that remedial actions must (1) protect human health
and the  environment, (2)  comply with ARARs  (or justify a waiver), (3) be cost effective, and
(4) use permanent solutions and alternative treatment (or resource recovery) technologies to the
maximum extent practicable.  Additionally, CERCLA Section 121  establishes a preference for
remedial actions including, as a principal element of the remedy,  treatment that permanently and
significantly reduces the volume, toxicity or mobility of hazardous substances, pollutants, and
contaminants.  However,  for interim remedial actions, these requirements apply only within the
limited scope of the action.  For example, interim remedial actions are required to comply with
only those ARARs specific to the interim  action itself.

      This interim action provides short- and long-term protection of human health and the
environment through removal of a contaminant  source and limitation of the potential spread of
contamination.  This action will comply with all ARARs.   The action is cost-effective.   DOE
believes the selected interim action represents the maximum extent to which an interim action can
be used and  provides the  best balance  of trade-offs in  terms of short-term effectiveness,
implementability, and cost.  The action does not use treatment and  is not permanent within the
scope of the action. The  proposed action  also reduces the potential contaminant release and is,
therefore, appropriate for an interim purpose.
/TOOS89703.IWR/CJE                             2-19                                Augusl 25. 1997

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              EXPLANATION OF SIGNIFICANT CHANGES
      A review of all comments resulted in no significant changes to the remedy as originally
identified in the FS/PP.
                                REFERENCES

DOE (U.S. Department of Energy).  1997. Feasibility Study/Proposed Plan for Sludge Removal
      from the Gunite and Associated Tanks Operable Unit, Waste Area Grouping 1, Oak
      Ridge National Laboratory, Oak Ridge, Tennessee, DOE/OR/02-1509/V1&D2, and
      V2&D2.  Oak Ridge, TN.

DOE.  1996a.  Waste Isolation Pilot Plant Disposal Phase Draft Supplemental Environmental
      Impact Statement, DOE/EIS-0026-S-2.  DOE Carlsbad Area Office, Carlsbad, NM.

DOE.  1996b.  Addendum to the Remedial Investigation/Baseline Risk Assessment for the
      Gunite and Associated Tanks Operable Unit at Waste Area Grouping 1 at the  Oak
      Ridge National Laboratory, Oak Ridge, Tennessee, DOE/OR/02-1275&D2/A1.  Oak
      Ridge, TN.

DOE.  1994. Remedial Investigation/Baseline Risk Assessment for the Gunite and Associated
      Tanks Operable Unit at Waste Area Grouping I,  Oak Ridge, Tennessee, DOE/OR/02-
      1275&D2. Oak Ridge, TN.

ORNL (Oak Ridge National Laboratory).  1997a.  Evaluation and Monitoring Plan for
      Consolidation Tanks: Gunite and Associated Tanks Operable Unit,  Waste Area
      Grouping, Oak Ridge National Laboratory, Oak Ridge, Tennessee, ORNL/ER-396.
      Oak Ridge, TN.

ORNL.  1997b.  Baseline Monitoring and Simulated Liquid Release Test Report for
      Tank W-9, Oak Ridge National Laboratory,  Oak Ridge, Tennessee,  ORNL/ER-410.
      Vista Research, Inc., Oak Ridge, TN.

ORNL.  1984.  Sluicing Operations At Gunite Waste Storage Tanks,  ORNL/NFW-84/72.
      Oak Ridge, TN.
JT00589703.IWR/CJE                            2-20                              Augus 25, 1997

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              PART 3. RESPONSIVENESS SUMMARY
JTOOS89TO3.IWR/CJE                                                   Augusi 25, 1997

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                        RESPONSIVENESS SUMMARY

      The public comment period, originally scheduled for May 2,  1997, to June 2, 1997, was
extended to June 13, 1997.  DOE received written comments from three individuals or groups.
A letter supporting the project from the Site Specific Advisory Board along with DOE's responses
to these comments are included at the end of Section 3.  During the public meeting June 2, 1997,
DOE  responded to questions from four individuals in the  audience.  For  purposes  of this
Responsiveness Summary, all public comments have been combined into four discrete comments
with DOE responses.

Comment 1.  At the public meeting on June 2, 1997, several individuals indicated they felt
the FS/PP lacked a clear description of the overall  strategy and details of this particular
action.

      Response: In response to the request for a clearer description of the overall  remediation
strategy, an additional section entitled  "Decision Overview" has been added to the ROD. Also,
the descriptions  of the approach to tank cleaning and overall waste treatment and disposal have
been expanded in the ROD.

Comment 2.  Several individuals questioned pumping the waste  from each Gunite tank to
a consolidation  tank rather than directly to MVST.

      Response:  A consolidation tank is necessary to properly prepare the waste for batch
transfer  to MVST and  allow concurrent cleanup of the GAAT OU with other ORNL sites
containing TRU wastes.  MVST volume considerations, aggravated  by schedule constraints for
the  waste's final disposal at WIPP, require that consolidation and waste volume reduction  be
accomplished before transfer to  MVST.  Details of this approach have been added under the
"Decision Overview" section.

      The consolidation process provides the capability to even out  the flow from the waste
removal equipment and accumulate large enough  batches of waste for  efficient transfer to MVST.
Excess water generated during the waste removal process can be removed and sent to BVEST
for concentration, thereby maximizing the limited space available at  MVST. Most importantly,
the  consolidation approach will facilitate the eventual  transfer of the  waste to MVST.  Waste
removed from the Gunite tanks must be "conditioned" (particle size and water content adjusted)
before it can be  transferred to MVST through the mile-long pipeline between Bethel Valley and
Melton Valley.  DOE plans to install a conditioning system in the consolidation tanks similar to

JTOOS89703.IWR/CIE                             3-2                                August 25. 1997

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that used in the 1982 waste removal campaign which successfully avoided plugging the only route
for transfer of radioactive liquid waste from the main plant of ORNL to MVST (ORNL 1984).
DOE has thoroughly investigated the integrity of the Gunite tanks and  has selected Tanks W-8
and W-9 as the best candidates for use as consolidation tanks.  Additional tests of these tanks are
underway to confirm their integrity and demonstrate the effectiveness of a new leak monitoring
system that has been installed for the tanks.

Comment 3.  Several individuals expressed interest in specific details concerning conditioning
of the  waste  before transfer  to  MVST and the transfer  of the wastes  through  an
underground pipeline.

      Response: Available information on waste conditioning and transfer was discussed  at the
public meeting on June 2,  1997. However, final details of this process will be developed during
the ongoing treatability study.  When these details are developed they will be made available to
the public through the Information Resource Center.

Comment 4.  One individual expressed concern that the  total activity of the radioactive
material remaining in  the  tanks might be  higher  than the  estimate  used in the risk
assessment.

      Response:  The risk assessment narrative's figure of 40,000 Ci was  based on the most
recent sampling event at the time the estimate was prepared.  Previously, estimates in excess of
100,000 Ci have been advanced by parties with substantial  experience and knowledge of the
tank's contents.  However, because the waste  inventory is being  removed,  differences in this
range will not exclude the selection of this remedy.
JT00589703.IWR/CJE                               3-3                                 August 25. 1997

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    AK  RIDGE  RESERVATION
    Environmental   Management
                                June 17. 1997
  Mr. Rod Nelson
  Assistant Manager for Environmental Management
  DOE/ORO
  P.O. Box 2001
  OakRidce. TN 37831
  Dear Mr. Nelson:

  At our June 11, 1997 meeting, the Oak Ridge Reservation Environmental
  Management Site Specific' Advison.- Board (ORREMSSAB) reviewed and
  approved the enclosed recommendations for the Feasibility Study Proposed
  Plan (FS/PP) for Sludge Removal from the Gunite and Associated Tanks
  Operable Unit Waste Area Group 1, Oak Ridge National Laboratory. Oak
  Ridge. Tennessee.

  We  look  forward  to  receiving  your  written  responses  to  our
  recommendations.  Thank  you for your continued  support of the
  ORREMSS.AB.

                                Sincerely,
                                Randy Cordon, Chair
                                ORREMSSAB
  ER/RG/sb

  Enclosure

  cc:   Mr. John Hankinson, USEPA Region IV
       Mr. Earl Leming, TDEC/DOE/ORO
P.O. Box 2001 • Mail Slop EW-91 • Oak Ridge, TN 37B31 • K23) 241-3665

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                 Comments on the Feasibility Study/Proposed Plan (FS/PP) for
              Sludge Removal from the Gunite and Associated Tanks Operable Unit
                    Waste Area Group 1, Oak Ridge National Laboratory
                                  Oak Ridge, Tennessee
 The Oak Ridge Reservation Environmental Management Site Specific Advisory Board
 (ORREMSSAB) is in general accord with the second alternative described in the FS/PP to
 remove the bulk of the liquid and sludge from the gunite and associated tanks.  The no
 action alternative would be entirely unsatisfactory and quite problematic. Piping the
 activity to the more modern Melton Valley Storage Tanks to mix with similar wastes
 seems the correct course.

 The document describes the removal of sludges as an interim action and states that it is
 expected that the removed sludges will be sent to the Waste Isolation Pilot Plant (W1PP).
 Since the WIPP facility is not yet an operational facility, there should be discussion about
 the safety of storing the gunite tank waste in the Melton Valley Storage Tanks for an
 unknown interim period.  Either in this document or elsewhere, there should be
 contingency plans in case postponement of the WIPP continues indefinitely or WIPP does
 not open at all.

 The document also discusses that remedial action on the contents of TH-4 is being
 deferred until a later date. However, the program under which TH-4 will be addressed is
 not identified. Similarly, the remedial actions to address the tank shells, appurtenances,
 surrounding soils, and groundwater have not been identified, although it is our
 understanding that these actions will be addressed in the Bethel Valley Record of
 Decision. The public needs to be informed as to when and how deferred actions will be
 addressed.

 We assume that the most  efficient time to determine the post-transfer residual
 contamination of each tank is just after the sludge and liquids have been removed from
 that tank. The initial sampling plan outlined in the section describing alternatives (p.  11)
 will likely be too sparse unless video observations suggest that tank inner surfaces appear
 to be uniform and clean. The ORREMSSAB recommends that the Record of Decision
 explicitly outline a more comprehensive minimum sampling plan which will determine the
 nature of irregular features.  This information will allow for dependable plans to be
 developed for the future tank closures.
Recommendation 97.10                      1                      Approved June 11, 1997

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                            Department of Energy
                              Oak Ridge Operations Office
                                   P.O. Box 2001
                            Oak Ridge, Tennessee 37831—
                               August  6,  1997
Mr. Randall R. Gordon
3602 River Road
Ten Mile, Tennessee 37880

Dear Mr. Gordon:

RESPONSES TO SITE SPECIFIC ADVISORY BOARD COMMENTS ON GUNITE
TANKS REMEDIATION FEASIBILITY STUDY/PROPOSED PLAN D2

Thank you for your comments on the subject document.  Our response to your comments are
enclosed. We appreciate your input on this important Comprehensive Environmental Response,
Compensation, and Liability Act document to help ensure that the basis for our decisions is
explained and understood. Many of the comments you raised will be addressed in the Record of
Decision which is currently being prepared and in the Remedial Design Report/Remedial Action
work plan which will be prepared later this Fiscal Year.

If you have any questions, please call  Sandy Perkins at (423) 576-1590.

                                      Sincerely,
                                     Rodney R. Nelson
                                     Assistant Manager for
                                        Environmental Management
Enclosure
                                                                           ' PRINTED OK RECYCLED »A°cH

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                   Responses to Site Specific Advisory Board Comments
            On Gunite Tanks Remediation Feasibility Study/Proposed Plan D2

Comment 1.   The document describes the removal of sludges as an interim action and states that
it is expected that the removed sludges will be sent to the Waste Isolation Pilot Plant (WIPP).
Since the WIPP facility is not yet an operational facility, there should be discussion about the
safety of storing the Gunite tank waste in the Melton Valley Storage Tanks (MVST) for an
unknown interim period.  Either in this document or elsewhere, there should be contingency plans
in case postponement of the WIPP continues indefinitely or WIPP does not open at all.

Response The consolidation of all Oak Ridge National Laboratory (ORNL) Transuranic sludges
in the MVST for treatment and shipment to WIPP is a central component of the Site Treatment
Plan submitted under the provisions of the Federal Facilities Compliance Agreement. The Plan
calls for sludge transfers of 50,000 gallons from Gunite Tanks, 20,000 gallons from the Old
Hydrofracture Facility, and 30,000 gallons from the Bethel Valley Evaporator Service Tanks to be
consolidated with the 100,000 gallons of sludge currently located in the MVST. Specific
contingency plans have not been developed for the possibility that WIPP may not open and that
longer storage of the sludges in MVST might be required.  The MVST are fully permitted, "state
of the art," tanks which are expected to have continued service lives in excess of twenty five
years. This would provide sufficient time for the development and implementation of an
alternative approach to the long-term management of the sludges in the MVST should the need
arise.

Comment 2. The document also discusses that remedial action on the contents of TH-4 is being
deferred  until a later date. However, the program under which TH-4 will be addressed is not
identified. Similarly, the remedial actions to address the tank shells, appurtenances, surrounding
soils, and groundwater have not been identified, although it is our understanding that these actions
will be addressed in the Bethel Valley Record of Decision.  The public needs to be informed as to
when and how deferred actions will be addressed.

Response The Bethel Valley Watershed Record of Decision will include remedial action plans for
TH-4, several other smaller Gunite tanks, the eight large tank shells, appurtenances, surrounding
soils, and groundwater, in addition to the remainder of the Bethel Valley area. The current plans
call for the Dl Remedial Investigation/Feasibility Study to be issued June, 1998, the Dl Proposed
Plan to be issued November, 1998, and the Dl Record of Decision to be issued April, 1999.

Comment 3. We assume that the most efficient time to determine the post-transfer residual
contamination of each tank is just after the sludge and liquids have been removed from the tank.
The initial sampling plan outlined in the section describing alternatives (p. 11) will likely be too
sparse unless video observations suggest that the tank inner surfaces appear to be uniform and
clean. The Oak Ridge Reservation Environmental Management Sites Specific Advisory Board
recommends that the Record of Decision explicitly outline a more comprehensive minimum
sampling plan which will determine the nature of irregular features.  This information will allow
for dependable plans to be developed for the future tank closures.

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Response  The Department of Energy (DOE) plans to obtain the data to characterize the residual
contamination in the tanks shells at the completion of the waste removal and wall cleaning
activities. The details of the shell characterization are being developed as part of the on-going
Treatability Study, and are planned to be reflected in the Remedial Design Report/Remedial
Action Work Plan.

Based on information currently in hand, DOE expects that the sampling and analysis required for
the tank shells will be generally as described in the Feasibility Study/Proposed Plan. Based on
analyses performed in the  "Risk Assessment Pathway/Transport Modeling for the Gunite and
Associated Tanks (GAAT), ORNL" (DOE/OR/02-1454&D1, March 1996) there is no reasonable
scenario that would result in the GAAT shells being a risk after sludge removal, a "washing" of
the wall,  and then filling the tank with grout/concrete.  The controlling mechanism for any
radionuclides to contact groundwater around the exterior of the tanks is by diffusion. The rate of
diffusion for ^Sr, coupled with the relatively short half-life of 90Sr, is such that a remaining shell
inventory after tank cleaning of billions of curies would be required for the 90Sr levels at the
exterior of the tank to approach any risk level for ^Sr. The diffusion rates for other radionuclides
are slower than for ^Sr and these radionculides are not mobile in the environment.  Even if the
GAAT shell disintegrates in 300 years, these non-mobile radionuclides will be immediately
captured by surrounding soil, 20 plus feet underground.  The small '"Sr inventory remaining after
clean out would have decayed through ten half-lives during this 300 period. There is nothing in
our experience or the literature to refute this logic. During the Treatability Study we will
investigate the logic and provide data to confirm this conclusion.

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