PB96-964612
                                 EPA/ROD/R10-96/147
                                 March 1997
EPA  Superfund
       Record of Decision:
       Idaho National Engineering Lab,
       (USDOE) Operable Unit 26
       (Stationary Low-Power Reactor-1 and
       Boiling Water Reactor Experiment-I Burial
       Grounds), Idaho Falls, ID
       12/1/1995

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                                       FEB 1 2 1996
                                     Wcnruwl1
                              DIVISION OF
                              ENVIRONMENTAL
                              QUM.ITY
  INEL-95/0282
January, 1996
            Record of Decision
   Stationary Low-Power Reactor-1 and
Boiling Water Reactor Experiment-I Burial
                   Grounds
           (Operable Units 5-05 and 6-01),
               and 10 No Action Sites
       (Operable Units 5-01,5-03, 5-04, and 5-11)
    u
         \
    -•>
      Idaho National Engineering Laboratory • Idaho Falls, Idaho

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                   Declaration of the Record of Decision

                                Site Name and Location
                           Stationary Low-Power Reactor-1 Burial Ground,
                       Boiling Water Reactor Experiment-I Burial Ground, and
                                   10 No Action Sites Within the
                         Auxiliary Reactor Area and the Power Burst Facility

                              Idaho National Engineering  Laboratory
                                        Idaho Falls, Idaho

                           Statement of Basis and Purpose
   This document presents the selected remedial action for the Stationary Low-Power Reactor-1 (SL-1) burial
ground, the Boiling Water Reactor Experiment-I (BORAX-I) burial ground, and 10 no action sites in Waste
Area Group 5. The remedial actions were selected in accordance with the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA) as amended by the Superfund Amendments and
Reauthorization Act (SARA) (hereafter referred to collectively as "CERCLA"), and is consistent, to the extent
practicable, with the National Oil and Hazardous Substances Pollution Contingency Plan. Information sup-
porting the selection of the remedies for the burial grounds is contained in the Administrative Record for the
SL-1 and BORAX-I burial grounds (Operable Units 5-05 and 6-01). The Administrative Record for Track 1
sites in Waste Area Group 5 contains information  regarding the 10  no action sites (Operable Units 5-01, 5-03,
5-04, and 5-11).

   The U.S. Department of Energy (DOE) is the lead agency for this decision.  The U.S.
Environmental Protection Agency (EPA) and the Idaho Department of Health and Welfare (IDHW)
have participated in the evaluation of the  final action alternatives.  The EPA and IDHW both concur
with the selection of the preferred remedy for the SL-1 and BORAX-I burial grounds and with the no
action determinations for the 10 Track 1 sites.

                                Assessment of the Sites
   Actual or threatened releases of hazardous substances from  die 6L-1 and BORAX-I burial grounds,
if not addressed by implementing the response action selected in this Record of Decision, may present a
current or potential threat to public health, welfare, or the environment.

   The 10 no action sites do not present a threat to human health or the environment.

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                          Description of the Selected Remedy
    The Idaho National Engineering Laboratory (INEL) has been subdivided into 10 waste area groups
 for investigation pursuant to the Federal Facility Agreement and Consent Order between the DOE,
 EPA, and IDHW.  The SL-1 burial ground is designated Operable Unit 5-05, one of 13 operable units
 in Waste Area Group 5; the BORAX-I burial ground is Operable Unit 6-01, one of five operable units
 in Waste Area Group 6. The major components of the selected remedy for both sites are:

    •   Containment by capping with an engineered barrier constructed primarily of native materials
    •   For BORAX-I implementation will include consolidation of surrounding contaminated surface
       soils for containment under the engineered cover
    •   Contouring and grading of surrounding terrain to direct surface water runoff away from the caps
    •   Periodic above-ground radiological surveys following completion of the caps to assess the
       effectiveness of the remedial action
    •   Periodic inspection and maintenance following completion of the caps to ensure cap integrity
       and surface drainage away from the barriers
    •   Access restrictions consisting of fences, posted signs, and permanent markers
    •   Restrictions limiting land use to industrial applications for at least 100 years following comple-
       tion of the  caps
    •   Review of  the remedy no less often than every five years until determined by the regulatory
       agencies to be unnecessary.
    The selected remedy addresses the principal threats posed by the burial  grounds by providing
shielding from ionizing radiation, a barrier to inhibit ecological and human  intrusion, and a long-lasting
cover to diminish the effects of wind and water erosion.

                                Statutory Determination
    The selected remedies are protective of human health and the environment, comply with federal
and state requirements that are legally applicable or relevant and appropriate requirements (ARARs) to
law ieuiedial actions, and are cost effective. These remedies utilize permanent solutions and alternative
treatment technologies to the maximum extent  practicable.  However, because treatment of the princi-
pal threats of the two burial grounds was not found to be practicable, this remedy does not satisfy the
statutory  preference for treatment as a principal element of the remedy. The EPA's preference for sites
that pose relatively low long-term threats or where treatment is impracticable is engineering controls,
such as containment.  The radioactivity at each burial ground precludes a remedy in which contami-
nants could be readily excavated and treated without unacceptable exposures to workers.  The primary
contributor to risk  is a short half-lived radionuclide more effectively managed by providing engineered
containment while allowing the radionuclide to decay naturally.

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   Because these remedies will result in radionuclide-contaminated substances remaining on site at the
burial grounds in excess of health-based levels, reviews will be conducted within five years after com-
mencement of the remedial actions. Subsequent reviews will be conducted no less often than every five
years thereafter to ensure that the remedies continue to provide adequate protection of human health and
the environment. The periodic reviews will be discontinued when the regulatory agencies determine the
sites no longer pose an unacceptable risk to human health or the  environment.
                                               iii

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    Signature sheet for the foregoing Stationary Low-Power Reactor-1 Burial Ground, the Boiling
Water Reactor Experiment-I Burial Ground, and 10 no further action sites in Waste Area Group 5 at the
Idaho National Engineering Laboratory Record of Decision between the U.S. Department of Energy
and the U.S. Environmental Protection Agency, with concurrence by the Idaho Department of Health
and Welfare.
M.
 ohn M.WcynskQ               .                                     Date
  anager
U.S. Department of Energy, Idaho Operations Office

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   Signature sheet for the foregoing Stationary Low-Power Reactor-1 Burial Ground, the Boiling
Water Reactor Experiment I Burial Ground, and 10 no further action sites in Waste Area Group 5 at the

Idaho National Engineering Laboratory Record of Decision between the U.S. Department of Energy

and the U.S. Environmental Protection Agency, with concurrence by the Idaho Department of Health
and Welfare.
   ick Clarke
Regional Administrator, Region 10
U. S. Environmental Protection Agency
                                                                    Date

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    Signature sheet for the foregoing Stationary Low-Power Reactor-1 Burial Ground, the Boiling
 Water Reactor Experiment I Burial Ground, and 10 no further action sites in Waste Area Group 5 at the
 Idaho National Engineering Laboratory Record of Decision between the U.S. Department of Energy
 and the U.S. Environmental Protection Agency, with concurrence by the Idaho Department of Health
 and Welfare.
Wallace N. Cory                  T                                 Date
Administrator
Division of Environmental Quality
Idaho Department of Health and Welfare
                                            VI

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                     Contents
 Declaration of the Record of Decision
 Acronyms and Abbreviations	Jx

 1.  Site Name, Location, and Description	1

 2.  Site History and Enforcement Activities	5
    2.1   SL-1    	6
    2.2   BORAX-I	7

 3.  Highlights of Community Participation	8

 4.  Scopes and Roles of Operable Units and
    Response Actions  	10

 5.  Site Characteristics	11
    5.1   SL-1	11
         5.1.1  Previous Investigations .	11
         5.1.2  Nature and Extent  	12
         5.1.3  Fate and Transport	16
    5.2   BORAX-I  	16
         5.2.1  Previous Investigations	17
         5.2.2  Nature and Extent  	17
         5.2.3  Fate and Transport	19

 6.  Summary of Site Risks  	20
    6.1   Human Health Risks	21
         6.1.1  Contaminant Identification  	21
           .2  Exposure Assessment	22
           .3  Toxicity Assessment	24
           .4  Human Health Risk Characterization
25
        6. .5  Uncertainty  	35
        6. .6  Conclusions	37
   6.2  Ecological Concerns 	38
        6.2.1  Species of Concern  	38
        6.2.2  Exposure Assessment	39
        6.2.3  Risk Characterization	39
   6.3  Basis  for Response  	39

7. Description of Alternatives	40
   7.1  Remedial Action Objectives and Applicable
        or Relevant and Appropriate Requirements .... 40
        7.1.1  Remedial Action Objectives  	40
        7.1.2  Applicable or Relevant and Appropriate
              Requirements  	41
   7.2  Summary of Alternatives	42
        7.2.1  No Action  	42
        7.2.2  Containment  	43
        7.2.3  Removal and Disposal	45

8. Summary of Comparative Analysis of
   Alternatives	46
   8.1  Threshold Criteria	46
         8.1.1  Overall Protection of Human Health
              and the Environment 	46
         8.1.2  Compliance with Applicable or Relevant
              and Appropriate Requirements	47
    8.2   Balancing Criteria 	47
         8.2.1  Long-Term Effectiveness and Permanence ... 47
         8.2.2  Reduction of Toxicity, Mobility, or
              Volume through Treatment	48
         8.2.3  Short-Term Effectiveness	48
         8.2.4  Implementability	48
         8.2.5  Cost	49
    8.3   Modifying Criteria	51
         8.3.1  State Acceptance  	52
         8.3.2  Community Acceptance	52

9.  Selected Remedy	52
    9.1   Description of Selected Remedy  	53
    9.2   Remediation Goals  	55
    9.3   Estimated Cost Details for the Selected Remedy  56

10. Statutory Determinations	59
    10.1  Protection of Human Health and the
        Environment  	59
    10.2 Compliance with ARARs	60
         10.2.1  ARARs  	60
         10.2.2  To-Be-Considered Guidance  	61
    10.3 Cost Effectiveness	61
    10.4 Use of Permanent Solutions and Alternative
        Treatment Technologies to the Maximum
        Extent Practicable  	61
    10.5 Preference for Treatment as a Principal Element . 63

11. Documentation of Significant Changes	63
    11.1 Surface Soil Consolidation	63
    11.2 Monitoring	64
        11.2.1   Groundwater Monitoring  	64
        11.2.2  Air Monitoring	64
         11.2.3  Soil Monitoring	65
    11.3 Cost Refinements	65
    11.4 Operable Unit 5-05 Boundary  	65
    11.5 Other Changes to the Proposed Plan  	.66

12. Decision Summary for No Action Sites	66
    12.1 Site Name, Location, and Description 	66
    12.2 Site History and Enforcement Activities	67
    12.3 Highlights of Community Participation  	68
    12.4 Scope  and Role of Operable Unit or
        Response Action 	68
         12.4.1   Auxiliary Reactor Area Sites  	68
        12.4.2  Power Burst Facility Sites 	68
    12.5 Site Characteristics  	69
    12.6 Summary of Site Risks  	69
         12.6.1  Wastewater Disposal Sites 	69
         12.6.2 Soil-Contamination Sites  	71
         12.6.3  Underground Storage Tanks 	71
    12.7 Description of the No Action Alternative	72
                                                      vii

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Appendices
   Appendix A  	A-l
        Responsiveness Summary	A-3
                                                         Figures
                                                         1.  Location of the SL-1 and BORAX-I burial grounds
                                                            at the INEL	 .2
        A.I    Overview  	A-3    2.  SL-1 burial ground site map	3
        A.2    Background on Community                  3.  BORAX-I burial ground site map	3
               Involvement  	A-3    4.  1990 isoplethic map of SL-1	13
        A.3    Summary of Comments with Responses A-5    5.  1990 isoplethic map of BORAX-I	13
        A.4    Comment and Response Index  	A-16    6.  Graphical summary of risk for SL-1 	31
    Appendix B  	B-l    7.  Graphical summary of risk for BORAX-I	33
        Administrative Record File Index	 . .B-3    8.  Graphical summary of external exposure risk based
        AR1.1  Background 	B-3       on measured radiological fields and natural
        AR1.7  Initial Assessments	B-5       background,  SL-1, and BORAX-I	35
        AR3.8  Risk Assessment	B-5    9.  Waste Area Group 5 facilities and no further
        AR3.10 Scope of Work  	B-6       action sites  	67
        AR3.12 Remedial Investigation/Feasibility
                Study 	B-6
        AR4.3  Proposed Plan	B-6

Tables
1.   Contaminants of concern and surface soil
    concentrations at SL-1   	14
2.   Potential contaminants  of concern and estimated
    subsurface concentrations at SL-1 for non-
    groundwater pathways   	15
3.   Contaminants of concern and surface soil
    concentrations at BORAX-I	18
4.   Potential contaminants  of concern and estimated
    subsurface concentrations at BORAX-I for
    non-groundwater pathways	 .19
5.   Summary of risks for the potential exposure scenarios
    and pathways at SL-1  	27
6.   Summary of risks for the potential exposure scenarios
    and pathways at BORAX-I	29
7.   Summary of risk assessment assumptions and
    associated uncertainties	36
8.   Summary of ARARs and criteria to be considered for
    alternatives	41
9.   SL-1 alternative cost estimates  	51
10. BORAX-I alternative cost estimates .. . .	51
11. SL-1 selected remedy detailed cost estimate	57
12. BORAX-1 selected remedy detailed
    cost estimate	58
A-l Estimates of dose for the 30-year residential
    intrusion  scenario	A-6
A-2 Minimum and maximum vadose zone water travel
    times (years) considered in the sensitivity/
    uncertainty analysis . . .'.	A-8
A-3 Index of comments	A-17
                                                    viii

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            Acronyms and  Abbreviations

    ARA    Auxiliary Reactor Area
   ARAR    applicable or relevant and appropriate requirements
BORAX-I    Boiling Water Reactor Experiment-I
      °C    degree(s) Celsius
CERCLA    Comprehensive Environmental Response, Compensation, and Liability Act
    CFR    Code of Federal Regulations
      cm    centimeter(s)
    DOE    U.S. Department of Energy
 DOE-ID    U.S. Department of Energy, Idaho Operations Office
    EPA    U.S. Environmental Protection Agency
      °F    degrees Fahrenheit
       g    gram(s)
  IDAPA    Idaho Administrative Procedures Act
   IDHW    Idaho Department of Health and Welfare
   INEL    Idaho National Engineering Laboratory
     km    kilometer(s)
      m    meter(s)
     m2    square meter(s)
     mg    milligram(s)
     mR    milliroentgen
 firem/hr    microroentgen equivalent man per hour
     nCi    nanocurie(s)
    PBF    Power Burst  Facility
     pCi    picocurie(s)
   RI/FS    Remedial Investigation/Feasibility Study
   SARA    Superfund Amendments and Reauthorization Act
     sec    second
    SL-1    Stationary Low-Power Reactor-1
    TBC    To-Be-Considered
   WAG    Waste Area Group
      yr    year
                                 ix

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                                Decision Summary

                       1. Site Name, Location, and Description
    The Idaho National Engineering Laboratory (INEL) is a government facility managed by the
 U.S. Department of Energy (DOE). The main security gate in the southern portion of the site is located
 44 miles (71 km) west of Idaho Falls, Idaho. The INEL occupies 890 square miles (2,305 km2) of the
 northeastern portion of the Eastern Snake River Plain. The Stationary Low-Power Reactor-1 (SL-1)
 and Boiling Water Reactor Experiment-I (BORAX-I) burial grounds are approximately 38 and 52 miles
 (61 and 84 km) west of Idaho Falls (Figure 1).

    The SL-1 site is located about 1,600 feet (488 m) northeast of the Auxiliary Reactor Area n and
 includes the surface-soil area surrounding a 600- by 300-foot (182.9- by 91.4-m) fenced burial ground
 (Figure 2). Approximately 99,000 cubic feet (2,800 m3) of radionuclide-contaminated debris, soil, and
 gravel are disposed of in  the burial ground. An estimated 2 feet (0.6 m) of soil with a thick grass cover
 lies over the waste.

    The BORAX-I burial ground is located about 2,730 feet (832 m) northwest of the Experimental
 Breeder Reactor-1,  a national monument. The BORAX-I site includes a 200- by 420-foot (61- by
 128-m) surface-soil contamination area surrounding the 100- by 100-foot (30- by 30-m) fenced burial
 ground (Figure 3).  The volume of buried radionuclide-contaminated soil and debris is approximately
 6,336 cubic feet (180 m3). The 84,000-square foot (7,800-m2) area was covered with 6 inches of
 gravel in 1954, but grass, sagebrush, and other plants have reseeded the area since then.

   The INEL was originally established as the National Reactor Testing Station by the U.S. Atomic
 Energy Commission in 1949. The National Reactor Testing Station's mission was to build, test, and
 operate nuclear reactors, fuel processing plants, and support facilities. The INEL's current mission, as
 directed by the DOE, is the integration of engineering, applied science, and operations in an environ-
 mentally conscious, safe, and cost-effective manner.

   The SL-1 and BORAX-I burial grounds are historical disposal areas and do not host any current
 programs. Current activities are limited to periodic observations for maintenance of the fences and
 grounds and monitoring for radioactivity.

   Of the approximately 11,700 people employed at the INEL, none work full time at either burial
ground. There are no residential communities within the INEL boundaries.  The nearest residential
community is Atomic City, located approximately 1 mile (1.6 km) south of the INEL boundary, with a
population of 25. Larger communities near the INEL include Idaho Falls, located approximately 44
miles  (71 km) to the east of the main gate, with a population of 43,973; Blackfoot, located approxi-
 mately 37 miles (60 km) to the southeast, with a population of 9,646; and Arco, located approximately
 19 miles (31 km) to the west, with a population of 1,016.

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   ARA     Auxiliary Reactor Area
   ANL-W  Argonne National Laboratory-West
   BORAX-I Boiling Water Reactor Experiment I
   CFA     Central Facilities Area
   EBR-I    Experimental Breeder Reactor I
   EBR-II   Experimental Breeder Reactor II
   ICPP    Idaho Chemical Processing Plant
   IET      Initial Engine Test
   LOFT    Loss-of-Fluid Test (facility)
   NRF     Naval Reactor Facility
   PBF     Power Burst Facility
   RWMC  Radioactive Waste Management Complex
   SL-1     Stationary Low-Power Reactor No. 1
   TAN     Test Area North
   TRA     Test Reactor Area
   TSF     Technical Support Facility
   WRRTF  Water Reactor Research Test Facility
               INEL boundary
               Roads
               Facilities
               Towns
               Pioneer Basin
               boundary
 To Salmon
                                                                                       ToDubois
                                                                                           INEL
                                                                                        890 square miles
                                                                                        2,305 square kilometers
                                                            ICPP
                                                                   PBF
                                                           CFA  /"ARA ill
                                                                    ARA
                           14 mi
              11
        Approximate scale
                           22km
                                 INEL boundary groundwater         INEL  Atomic City *N.
                                 receptor location for BORAX I   boundary groundwater         To Blackfoot
                                                      receptor location for SL-1
Pioneer Basin
Figure 1.  Location of the SL-1 and BORAX-I bur^l grounds at the INEL.
                                                    2

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                                                                                 Operable Unit 5-05
                                                                                                       LEGEND
                                                                                                  Fence
                                                                                                  Exclusion Fence
                                                                                                  Estimated boundwy of OU 5-05
                                                                                          ^••••M Area of surface soil evaluated
                                                                                                  in the taase(tn« nsk assessment
                                                                                          - — - — Estimated boundary of ARA-23
                                                                                                                             M950332
Figure 2.   SL-1 burial ground site map.
                                                          Figure 3.  BORAX-I burial ground site map.

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    Most of the area surrounding the INEL is either unimproved rangeland or farmland, and approxi-
mately 330,000 acres (1,300 km2) of the INEL are open to grazing by permit. However, grazing is
prohibited within 2 miles (3 km) of any nuclear facility, and no dairy cows are allowed. Approximately
95% of the INEL site has been withdrawn from the public domain by land transfer from the U.S.
Bureau of Land Management to the DOE.

    The climate of the region is arid to semiarid. Average annual precipitation is 8.71 inches (22 cm),
wind is generally from the southwest with average speeds of 5 to 9 miles per hour (8 to 15 km/hour),
and average air temperatures are 64.6°F (18.1°C) in the summer and 18.8°F (-7.3°C) in the winter.

    The INEL lies in the Pioneer Basin, a closed topographic depression located on the Eastern Snake
River Plain. Elevations range from approximately 4,800 to 5,400 feet (1,463 to 1,646 m) with a total
relief of about 600 feet (183 m).  The area receives surface water from rainfall, snowmelt, and stream-
flow.  The streamflow sources are the Big Lost River, the Little Lost River, and Birch Creek.
Streamflow that reaches the INEL goes to the Big Lost River playa or the Birch Creek playa and is lost
to evaporation and infiltration.  Consequently, there is little available surface water within the  INEL site
boundaries and none available at the SL-1 and BORAX-I sites.

    The Eastern Snake River Plain is a  broad, flat plain composed of thick basaltic flows covering rhy-
olitic calderas. The flows occur as layers of lava, ranging from a few inches to a few feet thick,  inter-
spersed with cinders, breccia, and unconsolidated sediments. Much of the INEL's land surface consists
of basalt flows. The western and central portions of the INEL lie within the floodplain of the  Big Lost
River, which extends across the site from the southwest to the  northeast. Alluvial deposits from  the
Big Lost River grade into lacustrine (lake) deposits in the northern portion of the INEL where the Big
Lost River enters 
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    The variety of habitats on the INEL support numerous species of reptiles, birds, and mammals.  Ten
 reptiles, including the short-horned lizard, the gopher snake, the sagebrush lizard, and the western rat-
 tlesnake, and one amphibian species, the Great Basin spadefoot toad, have been observed on the site.
 A total of 164 species of birds inhabit the INEL, including sparrows, raptors, waterfowl, swallows,
 American kestrels, killdeers, American robins, sage thrashers, sage sparrows, western meadowlarks,
 house sparrows, and mallards during the breeding season and sage grouse, rock doves, horned larks,
 and black-billed magpies year-round.  The 37 species of mammals found on the site include 18 species
 of rodents, four species of leporids, and six species of carnivores. The most common rodents are the
 Townsend's ground squirrel, the least chipmunk, the Great Basin pocket mouse, and Ord's kangaroo
 rat; the dominant leporid is the rabbit; common carnivores are the coyote and the long-tailed weasel.
 Pronghorn antelope and mule deer are frequently observed.

    Only two species  have been identified at the INEL that are classified as endangered or threatened:
 the bald eagle and the American peregrine falcon. The bald eagle has been seen in the winter months
 at or around the INEL, and the peregrine falcon has been observed in the northern portion of the INEL
 on rare occasions.

                      2.  Site History and Enforcement Activities
    The SL-1 and BORAX-I burial grounds were constructed to dispose of contaminated debris, soils,
 and gravel generated by the  destruction of a small nuclear reactor at each location.  The BORAX-I bur-
 ial ground was established in 1954; the SL-1 burial ground was established in 1961. Both sites were
 identified in the Consent Order and Comph'ance Agreement which was signed by the EPA and the DOE
 and promulgated in 1987 pursuant to the Resource Conservation and Recovery Act Section 3008(h).
 Under this agreement, the DOE initially assessed and screened the identified sites and established a
 procedure for conducting corrective actions.  Both burial grounds were identified as solid waste man-
 agement units. The INEL was proposed for listing on the National Priorities List in July 1989.  The
 listing was proposed by the EPA under authorities granted by the Comprehensive Environmental
 Response, Compensation, and Liability Act of 1980.  This act is also referenced by the acronym
 "CERCLA" or as the  "Superfund." The act was amended by the Superfund Amendments and
 Reauthorization Act of 1986. References to CERCLA include the amendments of 1986. The National
 Priorities List identifies the highest risk sites, as determined by a screening and ranking process, which
 are to be remediated via the  CERCLA process.  The INEL was officially placed on the National
 Priorities List in November 1989.

   Subsequent to the CERCLA listing, the DOE, the EPA, and the IDHW (collectively referred to as
 the agencies) negotiated a Federal Facility Agreement and Consent Order and an Action Plan for reme-
diation of the INEL. The documents were signed in December 1991. Both burial grounds were classi-
 fied as Track 2 operable units, described in the Action Plan as operable  units that may require field data
collection before a remedial  decision could be reached.  A Track 2 investigation would determine if no
further action, an interim action, or a remedial investigation/feasibility study was warranted.

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    Results of the 1993 Track 2 preliminary scoping for the SL-1 burial ground led the agencies to con-
clude that the evaluation of the site should be elevated to a remedial investigation/feasibility study. The
scope of the investigation was limited to existing data, considered sufficient by the agencies to deter-
mine a remedial action for the site, and a feasibility study focused on examining remedial alternatives
selected in other Records of Decision for similar sites. In addition, because of the similarities of the
BORAX-I burial ground to the SL-1 burial ground, the agencies determined that both sites would be
assessed in the same remedial investigation/feasibility study.

    This Record of Decision documents the remedy selected based on the results of the remedial inves-
tigation/feasibility study and additional information contained in the Administrative Record for
Operable Units 5-05 and 6-01.  Additional details concerning the history of each of the two burial
grounds follow in the next two subsections.

                                          2.1  SL-1
    The SL-1 was a small nuclear power plant designed for the military to generate electric power and
heat for remote arctic installations. The reactor was operated from August 1958 until January 3, 1961,
as a test,  demonstration, and training facility.  On the evening of January 3, 1961, the SL-1 reactor
accidentally achieved a prompt critical nuclear reaction, which caused a steam explosion that destroyed
the reactor and resulted in the deaths of the three operators on duty.  The reactor vessel and building
were severely damaged and highly contaminated, and a massive cleanup operation ensued to dismantle
and dispose of the reactor and building.

    A burial ground was constructed approximately 1,600 feet (488 m) northeast of the original  site of
the reactor. This was done to minimize radiation exposure to the public and site workers that would
have resulted from transport of contaminated debris from SL-1 to the Radioactive Waste Management
Complex over 16 miles (26 km) of public highway. Original cleanup of the site took about 18 months.
The entire reactor building, contaminated materials from nearby buildings, and soil and gravel contami-
nated during cleanup operations were disposed of in the burial ground.  The majority of buried materi-
als consists of soils and gravel.

    Recovered portions of the reactor core, including the fuel and all other parts of the reactor that were
important to the accident investigation, were taken to the ENEL's Test Area North for study. After the
accident investigation was complete, the reactor fuel was sent to the Idaho Chemical Processing Plant
for reprocessing.  The reactor core minus the fuel, along with the other components sent to Test Area
North for study, was eventually disposed of at the Radioactive Waste Management Complex.

    The SL-1 burial ground consists of three excavations, in which a total  volume of 99,000 cubic  feet
(2,800 m3) of contaminated material was deposited. The excavations were dug as close to basalt as the
equipment used would allow and ranged from 8 to 14 feet (2.4 to 4.3 m) in depth.  At least 2 feet
(0.6 m) of clean backfill was placed over each excavation.  Shallow mounds of soil over the excava-
tions were added at the completion of cleanup activities in September 1962. Operable Unit 5-05 is

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 defined as the surface and subsurface soils and debris within the 600- by 300-foot (183- by 91-m) SL-1
 burial ground exclusion fence and the surface area surrounding the burial ground (see Figure 2). Other
 residual surface contamination from the SL-1 accident is being investigated in Waste Area Group 5
 under Operable Unit 5-12, site code Auxiliary Reactor Area (ARA)-23, which is southwest of and adja-
 cent to Operable Unit 5-05 (see Figure 2). ARA-23 includes the original location of the SL-1 reactor.

    Numerous radiation surveys and cleanup of the surface of the burial ground and surrounding area
 have been performed in the years since the SL-1  accident.  Aerial surveys were performed by EG&G
 Las Vegas in 1974, 1982, 1990, and 1993. The Radiological and Environmental Sciences Laboratory
 conducted gamma radiation surveys every 3 to 4  years between 1973 and 1987 and every year between
 1987 and 1994. Particle-picking at the site was performed in 1985 and 1993.  Results from the surveys
 indicate that cesium-137 and its progeny (decay product) are the primary surface-soil contaminants.
 During a survey of surface soil in June 1994, "hot spots," areas of higher radioactivity, were found
 within the burial ground with activities ranging from 0.1 to 50 milliroentgen (mR)/hour. On
 November 17, 1994, the highest radiation reading measured at 2.5 feet (0.75 m) above the surface at
 the SL-1 burial ground was 0.5 mR/hour; local background radiation was 0.2 mR/hour. A dose equiva-
 lent rate survey was conducted in 1995; all locations surveyed within Operable Unit 5-05 yielded read-
 ings at or below the background value of 20 u,rem/hr.

    Today the SL-1 burial ground is defined by a  three-strand, barbed-wire exclusion fence posted with
 radiological control signs.  Inside the burial ground the ends of the excavations are identified by con-
 crete markers. The surface of the burial ground is covered with various grass species. The two
 mounds and several minor depressions due to subsidence are visible within the fenced area. A second
 radiological-control fence encompasses the burial ground, a larger contaminated surface soil area, and
 the Auxiliary Reactor Area I and n facilities.  The fences, posted with radiological-control signs, and
 restricted access protect INEL workers and the public from exposure.

                                       2.2  BORAX-I
    The BORAX-I reactor was a small experimental reactor used in the summer months of 1953 and
 1954 for testing boiling-water reactor technology. In 1954, the design mission of BORAX-I was com-
 pleted, and the decision was made to make one final test, whirv TS"lted in the intentional destruction
 of the reactor.  The destruction of the reactor contaminated approximately 84,000 square feet of the
 surrounding terrain. Immediately following the final test of the BORAX-I reactor, much of the
 radioactive debris, including some fuel residue, was collected and buried on site in the reactor shield
 tank.  Recovered fuel fragments and fuel residue  were sent to the Idaho Chemical Processing Plant and
 Oak Ridge National Laboratory in Tennessee. Reusable equipment associated with the reactor was
 successfully decontaminated and used in the construction of BORAX-II. However, the cleanup did not
 sufficiently reduce the radioactivity at the site; therefore, the 84,000-square foot (7,800-m2) contami-
nated area was covered with approximately 6 inches (15 cm) of gravel to reduce radiation levels at the
ground surface.

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    Buried materials at the site consist of unrecovered uranium fuel residue, irradiated metal scrap, and
contaminated soil and debris.  Part of the waste was buried in the bottom half of the shield tank; the top
half of the tank was collapsed into the bottom and the void space was filled with debris. The burial
ground is contained within the foundation of the BORAX-I installation, the dimensions of which are 18
by 32 by 11  feet (5.5 by 9.8 by 3.4 m). A mounded gravel and dirt cover approximately 5 feet (1.5 m)
high and 30  feet (9 m) in diameter is centered over the buried shield tank.  Operable Unit 6-01 includes
the buried debris, as well as the 84,000-square feet (7,800-m2) of contaminated surface soil.

    Field radiation surveys conducted in 1978 and  1980 detected radiation at about three times the
background  levels in the central portion of the gravel-covered 84,000-square foot (7,800-m2) area
south-southeast of the  buried reactor. Radiation in adjacent areas was at background levels. Surface
and subsurface soil sampling of the 84,000-square  foot (7,800-m2) gravel-covered area in 1978 and
1980 indicated that radioactive contamination exists and is highest at a depth of approximately 6 inches
(15 cm) at the interface of the gravel cover and the original ground surface.  Ongoing monitoring of the
site through  the use of radiation dosimeters shows that radiation levels are slightly above background
levels.  On November  18,  1994, the radiological field measured at 2.5 feet (0.75 m) above the surface
of the BORAX-I burial ground was 0.1  mR/hour; local background radiation was also 0.1 mR/hour.

   Today, the ground surface at the site looks very much like the surrounding terrain. Abundant native
vegetation has grown over the mound and surrounding area. A large stake about 5 feet (1.5 m) tall marks
the reactor location. A 6-foot (1.8-m)-high chain-link fence surrounds the burial ground, forming an
enclosed area approximately 100 feet (30 m) on each side. The contaminated surface soil area outside of
the chain-link fence is bounded by a two-wire exclusion fence. The fences, posted with radiological-control
signs, and restricted access  protect INEL  workers and the public from unacceptable exposures.

                      3. Highlights of Community  Participation
   In accordance with the CERCLA §113(k)(2)(B)(i-v) and §117, a  series of opportunities for public
information and participation in the remedial investigation and decision process for the SL-1 and
BORAX-I burial grounds was provided to the public from September 1994 through May 1995.  For the
public, notifications included fact sheets that briefly discussed the investigation to date, INEL Reporter
art'~'es nnd updates, a proposed plan, telephone briefings, and public meetings.  The INEL Reporter is
a periodic, public information publication of the INEL's Environmental Restoration Program.

   In September 1994, a fact sheet concerning the SL-1 and BORAX-I remedial investigation/feasibil-
ity study was sent  to about 6,700 individuals of the general public and to 650 INEL employees on the
INEL Community Relations Plan mailing list.

   The project was discussed at informal semiannual briefings in Twin Falls (October 11, 1994),
Pocatello (October 13, 1994), Moscow (October 18, 1994), Boise (October 19, 1994), and Idaho Falls
(October 20, 1994). During these briefings, representatives from the  DOE and the INEL discussed the
project, answered questions, and listened to public comments.
                                              8

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    Regular reports concerning the status of the project were included in the INEL Reporter and were
 mailed to those who were on the mailing list.  Reports also appeared in two issues of Citizens' Guide
 (a supplement to the INEL Reporter).

    In April 1995, another fact sheet concerning the project was sent to about 6,700 individuals of the general
 public and to 650 INEL employees on the INEL Community Relations Plan mailing list. On April 11,  1995,
 the DOE issued a news release to more than 100 contacts concerning the beginning of a 30-day public com-
 ment period, which began May 3, 1995, and ended June 3, 1995, pertaining to the SL-1  and BORAX-I pro-
 posed plan. Many of the  news releases resulted in a short note in community calendar sections of newspa-
 pers and in public service announcements on radio stations. Both the fact sheet and news release gave notice
 to the public that SL-1 and BORAX-I documents would be available before the beginning of the comment
 period in the Administrative Record section of the INEL Information Repositories located in the INEL
 Technical Library of Idaho Falls, in the INEL Boise Office, and in public libraries in Idaho Falls, Fort Hall,
 Pocatello, Twin Falls, Boise, and Moscow. Also, table top displays were set up at the Grand Teton Mall in
 Idaho Falls (May 15-20),  Burley Public Library (April 24-May 5), Twin Falls Public Library (May 5-26),
 Boise Towne Square Mall (April 29), and the Pocatello City Building (April 24-May 15).

    Opportunities for public involvement in the decision process for the SL-1 and BORAX-I project
 began in May  1995.  For the public, the activities included receiving the proposed plan, receiving tele-
 phone calls, attending the availability sessions at public meetings to informally discuss the issues,  and
 submitting verbal and written comments to the agencies during the 30-day public comment period.

    Copies of the proposed plan for SL-1 and BORAX-I were mailed to about 6,700 members of the pub-
 lic and to 650 INEL employees on the INEL Community Relations Plan mailing list on April 28, 1995,
 urging citizens to comment on the proposed plan and to attend public meetings.  Display advertisements
 announcing the same information and the locations of public meetings on May 16, 17, and 18, 1995, in
 Idaho Falls, Boise, and Moscow, respectively, appeared in seven major Idaho newspapers.  Large adver-
 tisements appeared in the following newspapers on April 26: the Post Register (Idaho Falls); the Idaho
 State Journal (Pocatello); the South Idaho Press (Burley); the Times News (Twin Falls); the Idaho
 Statesman (Boise); the Lewiston Morning Tribune (Lewiston); and the Daily News (Moscow).

    Post cards were mailed on May 10, 1995, to about 6,700 members of the public and to 650 INEL
 employees on the INEL  Community Relations Plan mailing list to encourage them to attend the public
 meetings and to provide  verbal or written comments. News releases and newspaper advertisements
gave public notice of public involvement activities. Offerings for briefings and the 30-day public com-
ment period that was to begin May 3 and run through June 3, 1995 were also announced. Personal
calls were made to stakeholders in Idaho Falls, Pocatello, Twin Falls, Boise, and Moscow the weeks of
May 8 and 15 to remind individuals about the meetings.

    Written comment forms, including a postage-paid business-reply form, were made available to
those aftending the public meetings.  The forms were used to submit written comments either at a

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 meeting or by mail. The reverse side of the meeting agenda contained a form for the public to evaluate
 the effectiveness of the meetings. A court reporter was present at each meeting to keep transcripts of
 discussions and public comments.  The meeting transcripts were placed in the Administrative Record
 sections for SL-1 and BORAX-I, Operable Units 5-05 and 6-01, in five INEL Information
 Repositories. For those who could not attend the public meetings but wanted to make formal written
 comments, a postage-paid written comment form was attached to the proposed plan.

    A Responsiveness Summary has been prepared as part of the Record of Decision. All formal verbal
 comments, as given at the public meetings, and all written comments,  as submitted, are included in
 Appendix A and in the Administrative Record for the Record of Decision.  Those comments are annotated
 to indicate which response in the Responsiveness Summary addresses  each comment.

    A total of about 10 people not associated with the project attended the SL-1/BORAX-I public
 meetings. Overall, 10 provided formal comment; of these 10 people, three provided oral comments,
 and seven provided written comments. All comments received on the proposed plan were considered
 during the development of this Record of Decision. The decision for this action is based on the infor-
 mation in the Administrative Record for these operable units.

    On August 2,  1995, the project manager from the Idaho Department of Health and Welfare Division
 of Environmental Quality gave a brief presentation on the projects to the Environmental Management
 Site Specific Advisory Board — Idaho National Engineering Laboratory. The advisory board is a
 group of individuals representing the citizens of Idaho, making recommendations to DOE, EPA, and
 the state of Idaho regarding environmental restoration activities at the INEL.

          4.  Scopes and Roles of Operable Units and Response Actions
   Under the Federal Facility Agreement and Consent Order, the INEL is divided into ten waste area
groups.  Each waste area group is further subdivided into operable units, each of which may contain one or
more sites. The first nine waste area groups correspond to particular operating facilities on the INEL; the
tenth waste area group represents the entire INEL and the Snake River Plain Aquifer. The SL-1 site is part
of Waste Area Group 5, which contains 13  operable units and is the only site in Operable Unit 5-05. The
BORAX-I site is in Waste Area Group 6 and is the only site in Operable Unit 6-01. A complete evaluation
of all cumulative risks associated with CERCLA action in Waste Area Groups 5  and  6 will be addressed in
the respective comprehensive remedial investigation/feasibility study for each waste area group.
Cumulative risks for the entire INEL will be addressed in the Waste Area Group 10 risk assessment.

   Existing data from past operating and disposal activities were available to  expedite the evaluation of
these sites. Therefore, the scope of the remedial investigation for the SL-1 and BORAX-I burial
grounds did not include any sampling or acquisition of new data, and a Work Plan was not produced.
A focused feasibility study, one that examined only those alternatives that had been previously selected
in Records of Decision for similar sites, was performed.

                                              10

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    The SL-1 site is defined as the buried waste in the SL-1 burial ground plus the surface soils in the sur-
 rounding area shown in Figure 2. The BORAX-I site is defined as the buried waste in the BORAX-I burial
 ground plus the surface soil in the surrounding 84,000-square foot (7,800-m2) area illustrated in Figure 3.
 This Record of Decision addresses the contaminated surface soils and buried wastes at both burial grounds.
 Both of these sites pose unacceptable risk to human health and the environment, primarily because of the
 risks from direct exposure to ionizing radiation from the buried wastes. There is also a lesser but still unac-
 ceptable nsK due to soil ingestion. The purpose of this response is to inhibit current or future exposure to
 the buried waste and to reduce risks from soil ingestion.

                                  5. Site Characteristics
    This section summarizes the historical data used to evaluate contamination at the SL-1 and BORAX-I
 burial grounds. The agencies determined that sufficient data exist to recommend a remedial action for
 each site, therefore, no sampling was conducted for the remedial investigation. A complete discussion of
 the site characteristics for the SL-1 and BORAX-I burial grounds can be found in the remedial investiga-
 tion/feasibility study and the Administrative Record for Operable Units 5-05 and 6-01.

                                          5.1  SL-1
    On January 3, 1961, the SL-1 reactor was destroyed by an accidental nuclear excursion that resulted in
 a steam explosion. Very little contamination was released to the environment at the time of the accident
 due to the containment provided by the reactor building; however, demolition and cleanup activities result-
 ed in the spread of contamination over surface soils from Auxiliary Reactor Area n to the SL-1  burial
 ground. Numerous radiological surveys, surficial soil sampling, and particle-picking activities have been
 conducted in the years since the accident. The following section summarizes the results of these activities.

 5.1.1  Previous Investigations
    The DOE's Radiological and Environmental Sciences Laboratory conducted gamma radiation sur-
 veys in the vicinity of Auxiliary Reactor Areas I and n and the SL-1 burial ground every 3 to 4 years
 between 1973 and 1991.  The areas north of Auxiliary Reactor Areas I and II and northeast of the SL-1
 burial ground had the highest gamma radiation intensities. Soil sampling in 1977 found that
 cesium-137 was the primary contaminant.

   The INEL's Waste Management Group surveyed areas in the vicinity of Auxiliary Reactor Area O
 and outside of the SL-1 burial-ground fence in 1985.  The survey identified  and mapped 236 radioactive
particles, of which 219 had maximum surface readings of 20 mR/hour or  greater. Of these, 16 had read-
ings greater than 200 mR/hour (the maximum reading possible for the instruments used in the survey).
A total of 44 of the particles were removed.  Particles with readings greater than 200 mR/hour that were
located on the road between Auxiliary Reactor Area n and the burial ground or were located in the dis-
turbed area across Fillmore Boulevard from Auxiliary Reactor Area n were  removed.

   The INEL's Environmental Monitoring Unit conducted annual radiological surveys of surface soils
within the SL-1 burial ground fence from 1987 through 1992.  One-third of the area was  surveyed each
                                              11

-------
 year; at the end of each three-year period, the entire area had been surveyed.  From 1987 to 1989, read-
 ings ranged from 0.05 to 11.0 mR/hour measured at contact. From 1990 to 1992, readings ranged from
 0.04 to 4.42 mR/hour measured at contact.

    In 1993, the Environmental Monitoring Unit performed a surface-soil radiological survey and parti-
 cle-picking at the SL-1 burial ground. There were 874 particles identified with readings from 0.01 to
 200 mR/hour at contact.  Particles reading greater than 0.15 mR/hour were removed if they were locat-
 ed hi the top 3 inches (7.6 cm) of soil. Of the 874 particles, 709 were removed for disposal at the
 Radioactive Waste Management Complex. Activity levels of the particles deeper than 3 inches
 (7.6 cm) and left in place ranged from 0.01 to 50 mR/hour.

    As part of the 1993 effort, an area immediately adjacent and northeast of the burial ground was
 investigated.  Of the 163 particles identified, 66 were removed.  The remaining particles were located
 at a depth of greater than 3 inches (7.6 cm) and had activities ranging from 1.0 to 250 mR/hour.  Three
 soil samples were collected from a depth of 0 to 1 foot (0 to 0.3 m).

    Four soil samples were collected from the vicinity of the SL-1 burial ground in a separate, unrelat-
 ed sampling effort conducted in 1993 as part of the Waste Area Group 3 and Waste Area Group  10 soils
 treatabih'ty study. The soil samples were analyzed for gross alpha, gross beta, and cesium-137.

    A surface-soil survey in June 1994 found 217 particles within the burial-ground fence, with activi-
 ties ranging from 0.1 to 50 mR/hour.  There were 51 particles identified in the area just northeast of the
 burial ground, with activities  ranging from 0.2 to 250 mR/hour.  In November 1994, a survey was con-
 ducted to determine radiation levels within the burial ground at a height of 2.5 feet (0.8 m).  A maxi-
 mum of 0.5 mR/hour was detected at two locations; the remainder of the area was at the local back-
 ground of 0.2 mR/hour.

    Aerial surveys of the SL-1 burial ground were conducted in 1974, 1982, 1990, and 1993. The sur-
 veys detected gamma radiation from man-made sources in the area, with cesium-137 the primary con-
 tributor.  The 1990 survey, which was used to define the site boundary, is illustrated in Figure 4. A risk
 assessment was completed in August 1995 on the basis of soil samples and dose equivalent rate mea-
 surements within the isopleth defined by the 1990 aerial survey (see Section 11.1).

 5.1.2 Nature and Extent
    5.1.2.1 Surface Contamination. Operable Unit 5-05 comprises the area illustrated in Figure 2.
 Based on the original source of surface contamination  (aerial distribution of contaminants during
demolition and cleanup of the SL-1 reactor) and the limited mobility of radionuclides  in the  soil at the
INEL, it is believed that contamination is restricted to  the upper 0.5 foot (0.15 m) of soil.  For the
remedial investigation, identification of the contaminants of concern associated with surface soils at
 SL-1 was based on comparison of analytical data with background concentrations.  Concentrations of
                                             12

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                            Mill      I
                            fflSL-1 Burial

                                 ound
 Figure 4.  1990 isoplethic map of SL-1.
        BORAX-V
        B
                                                         Letter
                                                         Label
                 Counts per
                   second
  A

  B

  C

  D

  E
G   < 1,100

      1,100-3,500

      3,500-11,000

      11,000 - 35,000

      35,000-110,000
                                                       Preliminary Data Results. The data shown
                                                       here have been processed in a manner
                                                       that suppresses the natural background.
                                                       The results are displayed as relative levels
                                                       of manmade radionudide activity. It is
                                                       nearly impossible to convert the relative
                                                       levels of activity to a meaningful exposure
                                                       rate because of the complex distribution
                                                       of the nudides.
                                                                     Feet
                                                       0      1,000    2,000    3,000
                                                       I          '          i           i
                                                       I          '         '        ^r
                                                       0       300     600      900
                                                                   Meters
  Letter        Counts per

  Label          second

             < 1,100


  B   LJ   1,100-3,500


  C   BUD   3,500 -11,000


  D   |   11,000 - 35,000

 Preliminary Data Results. The data shown
 here have been processed in a manner
 that suppresses the natural background.
 The results are displayed as relative levels
 of manmade radionudide activity. It is
 nearly impossible to convert the relative
 levels of activity to a meaningful exposure
 rate because of the complex distribution
 of the nudides.
                                                                    Feet
                                                      0       1,000     2,000    3,000
0       300      600
            Meters
                                                                                 900
Figure 5.  1990 isoplethic map of BORAX-I.
                                                  13

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 the contaminants of concern for surface soils were based on the 95% upper confidence limit of the ana-
 lytical data, and the assumption was made that each contaminant is uniformly distributed across the
 site.  Table 1 presents the contaminants of concern for surface soils.

    An assessment of the surface soils surrounding the SL-1 burial ground was concluded in August
 1995 subsequent to the remedial investigation and proposed plan.  Based on the results of this assess-
 ment, all dose equivalent rates within the Operable Unit are at or below the background value of 20
 uxem/hr.

 Table 1. Contaminants of concern and surface soil  concentrations at SL-1.
                                                                Concentration (pCi/g)
 Radionuclide                                  95% upper confidence limit    INEL Backgrounda
Cobalt-60
Cesium-137
Europium-154
Strbntium-90
Thorium-228
Thorium-230 and/or uranium-234
Thorium-232
0.36
904
2.68
1,370
 1.6
 2.7
 1.4
No data available
      1.28
No data available
      0.76
      2.1b
   1.88, 1.95
      2.1b
a. 95%/95% upper tolerance limit, grab sample background concentrations from Background Dose Equivalent Rates and
  Surficial Soil Metal and Radionuclide Concentrations for the Idaho National Engineering Laboratory, INEL-94/0250,
  S. M. Rood, G. A. Harris, G. J. White, February 1995.
b. Thorium-228 and -232 were retained for evaluation based on background data that were available when the remedial investiga-
  tion was prepared; the above-referenced background document was released after the remedial investigation was finalized.

    5.1.2.2 Subsurface Contamination.  Subsurface contamination at the SL-1 burial ground is
restricted to the excavations that received contaminated building debris, equipment, and gravel and soil
from the demolition and cleanup following the SL-1  reactor accident.  The estimated volume of buried
contaminated material is 99,000 cubic feet (2,800 m3).

    The inventory and activities of radionuclides in the subsurface of the SL-1 burial ground were estimated
using the computer model ORIGEN2. Because 93% of the uranium-235 fuel was recovered during the acci-
dent investigation and cleanup, it was assumed that only 7% of the original quantity of fuel was disposed of in
the  SL-1 burial ground. Inventories of radionuclide activities were generated for 1961, 1994, 2024, and 2094
and were utilized in the baseline risk assessment to calculate risks for current, 30-year future, and 100-year
future scenarios.  Inventories were calculated for specific times to account  for the decay (decrease through
time) of parent radionuclides and the ingrowth (an increase through time) of radioactive progenies. The con-
centration of each contaminant of concern for each time evaluated was estimated using the assumption that
7%  of the model-generated activity for each contaminant of concern was uniformly distributed  throughout the
source volume. Table 2 presents contaminants of concern for the subsurface and estimated concentrations.
                                               14

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Table 2. Potential contaminants of concern and estimated subsurface concentrations at SL-1 for
non-groundwater pathways.
Radionuclide
Cesium- 137
Strontium-90
Krypton-85
Samarium- 151
Promethium-147
Plutonium-241
Europium- 154
Europium- 155
Plutonium-239
Technetium-99
Plutonium-238
Arnericium-241
Plutonium-240
Zirconium-93
Niobium-93m
Antimony- 125
Europium- 152
Uranium-235
Cesium- 135
Uranium-236
Tellurium- 125m
Antimony- 126m
Tin- 126
Cesium- 134
Tin-121m
Antimony- 126
Neptunium-237
Iodine- 129
Palladium- 107
Uranium- 234
Uranium-238
Protactinium-231
Americium-242m
Actinium-227
Americium-243
Protactinium-234
Curium-243
Francium-223
Concentration (pCi/g)
July 1994 July 2024 July 2094
2.29E+04
2.15E+04
6.91E+02
5.20E+02
2.62E+01
1.96E+01
1.84E+01
1.24E+01
1.04E+01
6.85E+00
6.72E+00
2.57E+00
1.56E+00
1.04E+00
8.09E-01
7.30E-01
7.11E-01
4.60E-01
4.34E-01
2.32E-01
1.78E-01
1.78E-01
1.78E-01
9.12E-02
2.70E-02
2.49E-02
2.14E-02
1.12E-02
7.38E-U-;
6.28E-03
5.64E-03
3.34E-04
2.40E-04
1.31E-04
3.55E-05
7.33E-06
6.83E-06
1.81E-06
1.14E+04
1.05E+04
9.94E+01
4.13E+02
9.46E-03
4.62E+00
1.64E+00
1.87E-01
1.04E+01
6.85E+00
5.30E+00
2:93E+00
1.56E+00
1.04E+00
9.46E-01
4.01E-04
1.54E-01
4.60E-01
4.34E-01
2.32E-01
9.78E-05
1.78E-01
1.78E-01
3.81E-06
1.78E-02
2.49E-02
2.14E-02
1.12E-02
7.38E-03
6.79E-03
5.64E-03
6.26E-04
2.09E-04
3.60E-04
3.54E-05
7.33E-06
3.29E-06
4.96E-06
2.27E+03
1.99E+03
1.08E+00
2.41E+02
8.78E-11
1.59E-01
5.80E-03
1.05E-05
1.04E+01
6.85E+00
3.05E+00
2.76E+00
1.55E+00
1.04E+00
9.83E-01
9.89E-12
4.35E-03
4.60E-01
4.34E-01
2.32E-01
2.41E-12
1.78E-01
1.78E-01
2.30E-16
6.76E-03
2.49E-02
2.15E-02
1.12E-02
7.38E-03
7.60E-03
5.64E-03
1.31E-03
1.52E-04
l.OOE-03
3.52E-05
7.33E-06
6.00E-07
1.39E-05
                                             15

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 5.1.3  Fate and Transport
    Potential pathways for contaminant migration at the SL-1 burial ground are limited by site condi-
 tions.  The SL-1 site is fairly isolated, is gently sloped, is in a desert climate, and has a great depth to
 groundwater [approximately 667 feet (203 m)].  Although there is surface contamination at the site, the
 majority of contamination is subsurface.  In general, the potential pathways for contaminant migration
 include atmospheric transport and transport via surface water and groundwater.

    There  is a potential for windblown migration of radionuclides present in the surface soil at the SL-1
 burial ground, although the presence of a thick grass cover minimizes mobilization of dust and its dis-
 persion by wind.

    No surface-water migration pathway exists at the site, and there are no surface-water features. The
 SL-1 burial ground is in a topographic low, minimizing the chance for significant erosion due to sur-
 face water but increasing infiltration from precipitation.  Flooding of the  Big Lost River is  not a con-
 cern at SL-1 because of topography, distance from the river, and the INEL's flood diversion system.

    No groundwater sampling data are available  for the SL-1 burial ground, therefore the groundwater
 pathway was evaluated using the GWSCREEN (version 2.02) computer model. Concentrations in the
 groundwater were modeled for three hypothetical locations:  the edge of  the burial grounds, the down-
 gradient boundary of the waste area group (Figure 2), and the nearest downgradient INEL site-bound-
 ary (Figure 1). Groundwater flow is generally from northeast to southwest. The groundwater model-
 ing performed in support of the remedial investigation indicates that vertical migration of contaminants
 from the SL-1 burial ground is limited. The tendency of the contaminants to chemically react with nat-
 urally occurring minerals in the soil and low annual precipitation result in long transit times within the
 vadose zone (typically hundreds of years or more).  It is assumed that no  lateral migration of contami-
 nants has occurred within the subsurface because there is no mechanism or driving force to move cont-
 aminants horizontally.  Infiltration of precipitation is primarily vertical within the vadose zone and
 therefore would not contribute significantly to the horizontal migration of radionuclides.

                                       5.2  BORAX-I
    In 1954, the design mission  of the BORAX-I reactor was completed and the decision was made to
conduct one final experiment that would result in the destruction of the reactor.  The excursion contam-
inated approximately 84,000 square  feet (7,800-m2) of ground, in a strip  approximately 200 feet (61 m)
 wide and 420 feet (128 m) long, extending south-southeast from the reactor. Following cleanup, the
contaminated area of approximately 84,000 square feet (7,800-m2) was covered with gravel to a depth
of 6 inches (15 cm). Soil sampling of the 84,000-square foot (7,800-m2)  area of surface contamination
was conducted in 1978 and 1980. Results of these activities are summarized in the following section.
                                             16

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 5.2.1  Previous Investigations
    In 1978, the Radiological and Environmental Sciences Laboratory performed a multiphase study to
 assess the distribution of radioactivity at the BORAX-I reactor burial ground. Exposure rates at 3 feet
 (1m) above the ground were determined.

    A portable gamma-ray spectroscopy system was used to identify gamma-emitting radionuclides. In
 situ gamma-ray spectrums were obtained from nine locations. Surface-soil samples were also collected
 at nine locations outside of the graveled area in order to assess the extent of contamination. The col-
 lection locations were chosen to include samples down range of the major  debris and surface deposi-
 tion zones. Soil samples were collected from five locations within the gravel-covered area and were
 analyzed by gamma ray spectroscopy in order to assess the deposition and migration activity.  Analyses
 of the soil samples showed that cesium-137 and uranium-235 were the only detectable gamma-emitting
 radionuclides present. Samples collected from the gravel covering showed that 98% of the radioactive
 contamination was located within 2 inches (5 cm) of the gravel/soil interface.

    An investigation of the BORAX-I reactor area was conducted in June and November 1980. The
 investigation consisted of a gridded radiation survey of the BORAX-I site,  including high-resolution
 gamma spectrometer measurements of the surface soil,  soil samples from trenches, and sodium-iodide
 gamma spectrometer profiles of selected boreholes. The purpose of the radiological characterization
 was to identify the radionuclides  present within the area and to specify their concentrations and distrib-
 utions. Cesium-137 was the only man-made gamma emitter detected during the radiological surveys.
 Soil-sample analyses detected cesium-137, strontium-90, uranium-235, and plutonium-239.  Results
 indicate that surface contamination was limited to relatively small areas, mainly along a south-south-
 east line from the reactor location.

    Aerial surveys of the BORAX-I burial ground were conducted in 1974, 1982, 1990, and 1993. The
 surveys detected gamma radiation from man-made sources in the area, with cesium-137 being the pri-
 mary contributor.  Figure 5 illustrates the results of the  1990 survey.

 5.2.2  Nature and Extent
    5.2.2.1  Surface Contamination. Operable Unit 6-01 comprises an area approximately 200 by 420
 feet (61 by  128 m).  Based on the original source of surface contamination (aerial distribution  of conta-
 minants resulting from the final experiment of the BORAX-I reactor) and the limited mobility of
radionuclides in the soil at the INEL, it is believed that contamination is  restricted to the upper 1 foot  .
(0.3 m) including 0.5 foot (0.15 m) of contaminated soil and 0.5 foot (0.15 m) of gravel cover.

    Identification of the contaminants of concern associated with surface soils at BORAX-I was based
on comparison of analytical data  with background concentrations.  Concentrations of the contaminants
of concern for surface soils were  based on the 95% upper confidence limit  of the analytical data, and
the assumption was made  that each contaminant is uniformly distributed throughout the 200- by
420-foot (61- by 128-m) area.  Table 3 presents  the contaminants of concern  for surface soils.
                                             17

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Table 3. Contaminants of concern and surface soil concentrations at BORAX-I.

                                                              Concentration (pCi/g)
Radionuclide                                  95% upper confidence limit    INEL Background2

Cesium-137                                              1,817                      1.28
Strontium-90                                              2.0                      0.76
Uranium-235                                             68.6                  0.055 - 0.059b
a. 95%/95% upper tolerance limit, grab sample background concentrations for cesium-137 and strontium-90 from
  Background Dose Equivalent Rates and Surficial Soil Metal and Radionuclide Concentrations for the Idaho National
  Engineering Laboratory, INEL-94/0250, S. M. Rood, G. A. Harris, G. J. White, February 1995.
b. Range of background for uranium-235 from the remedial investigation/feasibility study, Attachment 1 of Appendix B.

    5.2.2.2 Subsurface Contamination. Subsurface contamination at the BORAX-I burial ground is
restricted to the contaminated soil and materials deposited in the concrete foundation of the reactor
structure. The estimated volume of contaminated material in the subsurface is 6,336 cubic feet
(180 m3).

    The BORAX-I inventory and activities of buried radionuclides were estimated using the computer
model RSAC-5. Decontamination documents prepared after the cleanup of the BORAX-I facility in
1954 reported that 12% of the uranium-235 fuel had been recovered. Based on this figure, it was
assumed that 88% of each of the associated radionuclides remained  unrecovered and was disposed of
in the burial ground. Inventories of radionuclides were generated for 1954, 1994, 2024, and 2094 and
were used in the baseline risk assessment to calculate risks for current, 30-year future,  and 100-year
future scenarios. Inventories were calculated for specific times to account for the decay (a decrease
through time) of parent radionuclides and for ingrowth (an increase  through time) of radioactive proge-
nies. The concentration of each contaminant of concern for  each time evaluated was estimated using
the  assumption that 88% of the model-generated activity for each contaminant of concern was uniform-
ly distributed throughout the source volume.  Table  4 presents the contaminants of concern for the sub-
surface.
                                              18

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 Table 4. Potential contaminants of concern and estimated subsurface concentrations at BORAX-I for
 non-groundwater pathways.
 Radionuclide
       Concentration (pCi/g)
July 1994     July 2024      July 2094
Cesium- 137
Strontium-90
Uranium-234
Samarium- 151
Uranium-235
Krypton-85
Technetium-99
Thorium-230
Promethium-147
Uranium-238
Zirconium-93
Niobium-93m
Protactinium-23 1
Tin- 126
Actinium-227
Cesium- 135
Antimony- 125
Radium-226
Lead-210
Iodine- 129
Protactinium-234
Europium- 154
Niobium-94
1.20E+03
1.10E+03
9.29E+02
5.05E+01
2.94E+01
1.90E+01
4.27E-01
3.34E-01
2.77E-01
1.91E-01
6.35E-02
5.57E-02
2.18E-02
1.10E-02
9.51E-03
8.29E-03
8.14E-03
2.88E-03
8.99E-04
6.02E-04
2.48E-04
1.12E-04
6.35E-07
6.02E+02
5.39E+02
9.29E+02
4.01E+01
2.94E+01
2.73E+00
4.27E-01
5.83E-01
l.OOE-04
1.91E-01
6.35E-02
6.21E-02
3.83E-02
1.10E-02
2.29E-02
8.29E-03
4.46E-06
8.77E-03
4.01E-03
6.02E-04
2.48E-04
9.96E-06
6.32E-07
1.19E+02
1.01E+02
9.29E+02
2.34E+01
2.94E+01
2.95E-02
4.27E-01
1.17E+00
9.25E-13
1.91E-01
6.35E-02
6.35E-02
7.65E-02
1.10E-02
5.95E-02
8.29E-03
1.10E-13
3.48E-02
2.25E-02
6.02E-04
2.48E-04
3.53E-08
6.32E-07
5.2.3 Fate and Transport
   Potential pathways for contaminant migration at the BORAX-I burial ground are limited by condi-
tions at the site. The site is fairly isolated, is gently sloped, is in a desert climate, and has a great depth
to groundwater [approximately 596 feet (181 m)]. Although there is surface contamination at the site,
the majority of contamination is in the subsurface.  In general, the potential pathways for contaminant
migration include atmospheric transport and transport by surface water and groundwater.

   There is a potential for windblown migration of radionuclides present in the surface soil at the
BORAX-I burial ground, although the existing vegetative cover minimizes the mobilization of dust and
its dispersion by wind.
                                             19

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    No surface-water migration pathway exists at the site and there are no surface-water features. Although
 the BORAX-I burial ground is located on a slight rise, the slope of the ground immediately adjacent to the
 site is fairly gentle, minimizing the likelihood of erosion. Hooding of the Big Lost River is not a concern at
 BORAX-I because of topography, distance from the river, and the INEL's flood diversion system.

    No groundwater sampling data are available for the BORAX-I burial ground, therefore the ground-
 water pathway was evaluated using the GWSCREEN (version 2.02) computer model. Concentrations
 in the groundwater were modeled for three hypothetical locations:  the edge of the burial grounds, the
 downgradient boundary of the waste area group (Figure 3), and the nearest downgradient EVEL site-
 boundary (Figure 1).  Regional groundwater flow is generally from northeast  to southwest.  Results of
 the modeling indicate that vertical migration of contaminants from the BORAX-I burial ground is lim-
 ited. The tendency of the contaminants to chemically react with naturally occurring minerals in the soil
 and low annual precipitation result in long transit times within the vadose zone (typically hundreds of
 years or more). It is assumed that no lateral migration of contaminants has occurred within the subsur-
 face because there is no mechanism or driving force to move contaminants horizontally. Infiltration of
 precipitation is primarily vertical within the vadose zone and therefore would not contribute significant-
 ly to the horizontal migration of radionuclides.
                                6.  Summary of Site Risks
    A baseline risk assessment was conducted to evaluate current and future potential risks to human
health.  The risk assessments were conducted in accordance with the EPA Risk Assessment Guidance
for Superfund, Volume I: Human Health Evaluation Manual and other EPA guidance. Risk scenarios
and default parameters used in the risk assessment were selected with the concurrence of the agencies.

    Radionuclides are the only contaminants of concern at the SL-1 and BORAX-I burial grounds.
Although nonradioactive contaminants may be present at either site, it was determined that, if present, they
probably represent an insignificant contribution to the total risk. Radionuclides present in surface soils at
BORAX-I and subsurface soils at both sites pose potential carcinogenic (cancer causing) risks to occupa-
tional workers and future residents. Carcinogenic risks are generally a much greater concern than noncar-
cinogenic risks from radionuclides. Therefore, the baseline risk assessment focused on a quantitative
assessment of carcinogenic risks. Noncarcinogenic risks were subjected to a qualitative evaluation and were
eliminated from further assessment. The assessment considered the carcinogenic health effects that could
result from exposure to the contaminants under current occupational and future occupational and residential
land use scenarios. The health effects differ depending on whether the sites are used for light industry or
residential development.  Effects could result from direct exposure to radiation, from inhalation of contami-
nated dust,  or from ingestion of contaminated soil or groundwater.  Section 6.1 summarizes the results of
the baseline risk assessment.

    The baseline risk assessment for Operable Unit 5-05 evaluated potentially contaminated surface
soils in an  area 1,200 by 1,500 feet (366 by 457 m).  Subsequent to finalization of the remedial investi-
gation/feasibility study report and the proposed plan, an evaluation of new data in conjunction with his-
                                               20

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 torical sampling and survey data determined that surface soils within Operable Unit 5-05 do not pose
 an unacceptable risk to human health or the environment (see Section 11.1). Support documentation
 for this determination can be found in the Administrative Record for Operable Units 5-05 and 6-01.

    A qualitative ecological risk assessment was performed to evaluate potential risks to the environ-
 ment due to contamination at the SL-1 and BORAX-1 burial grounds.  Section 6.2 summarizes results
 of the ecological risk assessment.

                                 6.1  Human Health Risks
    A baseline risk assessment was performed to evaluate the risks associated with taking no further
 action at a site. Thus, it was assumed in the assessment, as instructed in EPA guidance, that no remedi-
 ation will take place. Potential risks for specified land use scenarios were assessed.

    The risk assessment consisted of contaminant identification, exposure assessment, toxicity assess-
 ment, and human health risk characterization. The contaminants identified at the SL-1 and BORAX-I
 burial grounds were based on historical soil-sampling data  and radionuclide inventories calculated
 using computer models. The exposure assessment identified the potential exposure pathways for cur-
 rent workers and for future workers and residents. The toxicity assessment evaluated the potential
 health effects to an individual as a result of exposure to contaminants. Exposure scenarios were chosen
 to reflect a range of potential future land uses. Industrial land use is assured for the next 100  years,
 after which residential use is considered possible. Specifically, scenarios included the current use of
 the SL-1 and BORAX-I burial grounds (current occupational land use) and potential future land use
 scenarios (occupational and residential land use) in which the onset of exposures are delayed for 30
 and 100 years.

   The baseline risk assessment was presented in two parts:  (1) an evaluation of deterministic risk
based on standard EPA methodology and (2) an evaluation of the uncertainty associated with the mean
risk using probabilistic risk assessment. The first quantity (deterministic risk) is a point estimate that
represents a quantified upper bound of risk. Deterministic  risks are used by decisionmakers to define
the estimated excess risk that must be addressed in remedial decisions.  Probabilistic methods are used
in the second evaluation to quantify the uncertainty associated with the deterministic risk.  These meth-
ods provide a more complete understanding of the excess risk potential at a site by examining the like-
lihood of over- or under-estimation of risk.

6.1.1  Contaminant Identification
   Historical soil sampling analytical data were used to identify radionuclides present in surface soils
at both sites. The lists of radionuclides were screened based on comparison with background concen-
trations determined for the INEL. The range of sample concentrations was compared to the range of
background concentrations.  If the maximum sample concentration exceeded the maximum background
concentration, the radionuclide was retained and assessed in the risk assessment (Tables 1 and 3).

                                              21

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    Computer models were used to generate lists of radionuclides with estimated activities for the sub-
 surface at each site. The radionuclides were screened based on availability of lexicological data and
 potential for posing a significant risk. Radionuclides evaluated in the risk assessment for the subsur-
 face are presented in Tables 2 and 4.

 6.1.2  Exposure Assessment
    The objective of the exposure assessment was to estimate the magnitude of exposure to contami-
 nants of concern at SL-1 and BORAX-I.  The magnitude of exposure was determined by measuring or
 estimating the quantities of the contaminants available for contact at an exposure point during a speci-
 fied time period. The results of the exposure assessment were then combined with contaminant-specif-
 ic toxicity information to characterize potential risks.

    6.1.2.1 Exposure Scenarios. Only those exposure pathways where a plausible route of exposure
 can be demonstrated from the site to an individual were quantitatively  evaluated  in the risk assessment.
 The populations at risk due to exposure from wastes at the SL-1 and BORAX-I burial grounds were
 identified by considering both current and future land use scenarios. For each of the two sites,  10
 potential exposure scenarios (five residential scenarios and five occupational scenarios) were examined
 in the baseline risk assessment.

   The residential scenarios model a person living on the site 350 days a year for 30 years, beginning
 in 2024 and 2094 (30 and 100 years from 1994). The intrusive scenarios reflect  conditions if the
 buried waste is exposed.  The nonintrusive scenarios model the risk to  an individual who lives on  the
 surface above the wastes in 2024 and 2094 and to a subsistence farmer on the site beginning in  2094.

   The five occupational scenarios model nonintrusive daily industrial use without restrictions in 1994,
 two 1994 site-specific evaluations reflecting occupational activities over the last few years, and  daily
industrial use 30 and 100 years in the future in the years 2024 and 2094.  Section 6.1.2.3 lists exposure
parameters for each  scenario.

   6.1.2.2 Media Concentrations.  Limited sampling and analytical data were  available regarding
contaminants present in the surface and subsurface soil at the SL-1 and BORAX-I sites. Surface-soil
 samples from the burial grounds and adjacent areas were used to evaluate the risk for soil  ingestion,
inhalation of dust, and ingestion of crops, meat,  and milk for the nonintrusion scenarios.  Surface-sam-
ple data were also used to evaluate the external exposure pathway for the subsistence farmer scenarios.
Subsurface contamination was evaluated based on radionuclide inventories and activities estimated
using computer models. All pathways for the intrusion scenarios and the groundwater and external
exposure pathways for the nonintrusion scenarios were evaluated using the computer-generated
radionuclide inventories and activities.  The radionuclides  and concentrations evaluated in the baseline
risk assessment are listed in Tables 1 through 4.
                                             22

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    To provide an understanding of the external exposure risk present at the surface at the two sites,
risk attributable to the radiological field measurements taken within the fence at each burial grounds
was also evaluated.  A radiological field survey conducted in November 1994 found levels of 0.5
mR/hour at the SL-1 burial ground and 0.1 mR/hour at the BORAX-I burial ground.  Measurements
were taken at 2.5 feet (0.8 m) above the ground surface.  Local backgrounds were 0.2 mR/hour for
SL-1 and 0.1 mR/hour at BORAX-I. However, dose equivalent rates measurements taken in 1995 in
the area around SL-1 yielded readings at or below the background value of 20 (irem/hr.

    6.1.2.3 Quantification of Exposure. The following exposure pathways were considered applica-
ble to the evaluation of human exposure to contaminants at the sites: ingestion of soil; inhalation of
fugitive dust; ingestion of groundwater (residential scenarios only); ingestion of crops, meat, and milk
(subsistence farmer  scenario only); and external exposure from radionuclides.  The future residential
setting included a hypothetical well, which could provide contaminated groundwater for use as drink-
ing water. For the subsistence farmer scenario, the resident was also assumed to consume homegrown
produce, meat, and milk produced on site.

    Adult exposures were evaluated for all scenarios and pathways (external exposure; inhalation of
dust; and ingestion of soil, groundwater, and foods); child exposures (0 to 6 years old) were considered
separately only for the soil ingestion pathway in the residential scenarios.  Children were included
because children ingest more soil than adults, significantly increasing their exposure rate.

    The exposure parameters used in the risk assessment were obtained from EPA and DOE guidance.
The exposure parameter default values used in the risk assessment are designed to estimate the reason-
able maximum exposure at a site. The EPA defines reasonable maximum exposure as the highest
exposure at a site. Use of this approach makes under-estimation of the actual cancer risk highly  unlike-
ly.  Concentrations of the radionuclides evaluated in the baseline risk assessment are listed in Tables 1
through 4. The exposure parameters used in the risk assessment were:
    •   All pathways
       - Exposure frequency, residential:                  350 days/year
       - Exposure frequency, occupational, current:         2." J. ys/year
       - Exposure frequency, occupational, site-specific #1:   30 days/year
       - Exposure frequency, occupational, site-specific #2:    5 days/year
       - Exposure duration, occupational, current:               25 years
       - Exposure duration, occupational, site-specific #1 and #2:    3 years
    •   External exposure pathway
       - Exposure time, residential:                         24 hour/day
       - Exposure time, occupational:                        8 hour/day
       - Exposure duration, residential:                         30 years

                                              23

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    •  Soil ingestion pathway
       - Soil ingestion rate, residential, adult:                100 mg/day
       - Soil ingestion rate, residential, child:                200 mg/day
       - Soil ingestion rate, occupational:                     50 mg/day
       - Exposure duration, residential, adult:                    24 years
       - Exposure duration residential, child:                     6 years
    •  Dust inhalation pathway
       - Inhalation rate:                                20 m3 of air/day
       - Exposure duration, residential:                         30 years
    •  Groundwater ingestion pathway
       - Groundwater ingestion rate, residential:              2 liters/day
       - Exposure duration, residential:                        30 years.
    The parameters and distributions used in the probabilistic risk assessment are presented in Tables
6-9 through 6-11 of the Remedial Investigation/Feasibility Study Report for Operable Units 5-05 and 6-
01 (SL-1 and BORAX-I Burial Grounds), INEL-95/0027 (K. J. Holdren, R. G. Filemyr, D. W. Vetter,
Idaho National Engineering Laboratory, March  1995), which is included in the Administrative Record
for Operable Units 5-05 and 6-01.

6.1.3 Toxicity Assessment
    A toxicity assessment was conducted to identify potential adverse effects to humans from
contaminants at SL-1 and BORAX-I.  A toxicity value is the numerical expression of the substance
dose-response relationship used in the risk assessment.  Carcinogenic values (slope factors) for the
sites were obtained from EPA's Health Effects Assessment Summary Tables: Annual FY-93,
ECAO-CIN-909, 1993. The slope factors selected for the soil ingestion, inhalation of dust, and
external exposure pathways include progenies when available. Slope factors used to evaluate the
groundwater pathway do not always include daughters because the groundwater model GWSCREEN
specifically accounts for up to five daughters.

    Slope factors have been developed by the  EPA for estimating excess lifetime cancer risks associated
with exposure to potentially carcinogenic chemicals.  Slope factors for radionuclides are expressed in
units of risk/pCi for ingestion and inhalation and risk/year per pCi/gram for external exposure. Slope
factors are multiplied by the estimated intake  of a potential carcinogen, in pCi (pCi-year/gram for
external exposure), to provide an upper-bound estimate of the excess lifetime cancer risk associated
with the exposure at that intake level.  Slope factors are derived from the results of human epidemio-
logical studies or chronic animal bioassays to which animal-to-human extrapolation and uncertainty
factors have been applied.
                                              24

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 6.1.4  Human Health Risk Characterization
    Excess lifetime cancer risks are estimated by multiplying the intake level, developed using the
 exposure assumptions, by the slope factor (see Section 6.1.3). These risks are probabilities that are
 generally expressed in either scientific notation (1x10"^) or exponential notation (1E-06).  An excess
 lifetime cancer risk of 1E-06 indicates that, as a plausible upper bound, an individual has a one in one
 million chance of developing cancer as a result of site-related exposure to a carcinogen over a 70-year
 lifetime under the specific exposure conditions at a site.  Excess cancer risks estimated below 1E-06
 typically indicate that no further action is appropriate. Risks estimated in the range of 1E-04 to 1E-06
 (1 in 10,000 to 1 in 1,000,000) indicate that further investigation or remediation may be needed, and
 risks estimated above 1E-04 typically indicate that further action is appropriate. However, the upper
 boundary of the risk range is not a discrete line at 1E-04, although EPA generally uses 1E-04 in mak-
 ing risk management decisions. A specific risk estimate around 1E-04 may be considered acceptable if
justified based on site-specific conditions.

    6.1.4.1  Deterministic and Probabilistic Risk Summary. The results of the deterministic and
probabilistic risk calculations are summarized in Table 5 for SL-1 and in Table 6 for BORAX-I and
presented graphically in Figures 6 and 7. For the probabilistic simulations, the risk summary tables
and figures present the 50th percentile, representing the average individual risk, and the 95th percentile,
representing the reasonable maximum exposure individual risk.

    The probablistic risk assessment showed that the greatest contributors to uncertainty in the overall
risk for the site (that is, the risk due to external exposure) are associated with the exposure duration,
concentration of cesium-137, and the external exposure slope factor for cesium-137. A number of sce-
narios and pathways utilized source terms estimated from computer models.  Because of the lack of a
sample population from which to estimate statistical parameters for use in the probablistic simulations,
it was necessary to assume specific values for the parameters.  Increases in the amount of actual data
used for input into the probablistic assessment would  result in increased value and usefulness of the
results.

    At both sites, the primary contributor to risk is cesium-137 (plus progeny) in the external exposure
pathway. Cesium-137 has a half-life of about 30 years. The decreasing concentration through time
results in decreased risk through time.  External exposure risk will remain above 1E-04 for approxi-
mately the next 400 years at the SL-1  burial ground and will decrease  to 2E-04 after approximately 320
years at the BORAX-I burial ground.  Due to the long half-life of uranium-235 (7E+08 years), the
external exposure risk at BORAX-I will essentially never decrease below  2E-04.

   For SL-1, the only radionuclides predicted to reach the aquifer in concentrations of potential con-
cern were tritium and technetium-99, with associated  risks of 2E-07 and 6E-07, respectively.  Summed
with the risks from the remaining radionuclides, the total risk due to groundwater ingestion associated
with the SL-1 burial ground is 1E-06. For BORAX-I, uranium-234 and its progenies were the only
radionuclides predicted to reach the aquifer in concentrations of potential  concern, with a risk sum of

                                              25

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2E-06.  Summed with the risks from the remaining radionuclides, the total risk due to groundwater
ingestion associated with BORAX-I is 3E-06.

    For SL-1, an evaluation of risks due to surface soils defined by the 1990 aerial survey isopleth was
performed. It was determined that there are no unacceptable risks via the soil ingestion, inhalation of
dust, groundwater ingestion, or external exposure pathways within Operable Unit 5-25. Section 11.1
contains specific references contained in the Administrative Record in support of this assessment.

    6.1.4.2 Radiological Field Risk.  Surface radiological field measurements taken within the fences
at the burial grounds provide exposure levels that account for shielding of radiation provided by the
soil cover.  Based on the reported maximum, single point radiological field measurements of 0.5
mR/hour at SL-1 and 0.1 mR/hour for BORAX-I, the 30-year residential risk at the surface was esti-
mated at 9E-02 for SL-1 and 2E-02 for BORAX-I.  The risk associated with local background is 3E-02
at SL-1 and 2E-02 at BORAX-I. The risk associated with the average background radiological field at
the ENEL is 3E-03 (0.02 mR/hour). The 30-year residential risk from national average natural back-
ground radiation ranges from 2E-03 (0.011 mR/hour) to 6E-03  (0.034 mR/hour).   Risks based on radio-
logical field measurements taken within the fences are shown graphically in Figure 8.

    A more comprehensive data set for SL-1 was acquired in 1995 and an assessment of the surface
soils within Operable Unit 5-05 was completed in August 1995. Dose equivalent rate measurements,
all below the background value of 20 urem/hr, indicate no unacceptable external  exposure risks due to
surface soils within Operable Unit 5-05.
                                             26

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Table 5. Summary of risks for the potential exposure scenarios and pathways at SL-1.
Scenario
Pathway
Residential (30-year, intrusive)
External exposure
Ingestion of soil
Inhalation of dust
Ingestion of groundwater
Total scenario risk
Residential (30-year, nonintrusive)
External exposure
Ingestion of soil
Inhalation of dust
Ingestion of groundwater
Total scenario risk
Residential (100-year, intrusive)
External exposure
Ingestion of soil
Inhalation of dust
Ingestion of groundwater
Total scenario risk
Residential (100-year, nonintrusive)
External exposure
Ingestion of soil
Inhalation of dust
Ingestion of groundwater
Total scenario risk
Subsistence farmer (100-year)
(water independent pathways)
External exposure
Ingestion of soil
Inhalation of dust
Ingestion of plants
Ingestion of meat
Ingestion of milk
Total scenario risk
Occupational (current)
External exposure
Ingestion of soil
Inhalation of dust
Total scenario risk
Deterministic
risk

5E-01
9E-04
8E-07
1E-06
5E-01a

5E-01
5E-05
4E-07
1E-06
5E-01a

1E-01
2E-04
4E-07
1E-06
lE-01a

1E-01
9E-06
3E-07
1E-06
IE-OP


1E-03
4E-07
2E-06
1E-05
4E-05
1E-05
1E-038

2E-01
2E-05
4E-07
2E-018
Probabilistic
50th percentile
risk

1E-01
4E-05
2E-07
NCb
1E-01

1E-01
3E-07
7E-08
NCb
1E-01

3E-02
8E-06
1E-07
NCb
3E-02

3E-02
6E-08
7E-08
NCb
3E-02


NCC
NCC
NCC
NCC
NCC
NCC
NCC

8E-02
8E-08
9E-08
6E-02
Probabilistic
95th percentile
risk

6E-01
1E-04
9E-07
NCb
6E-01

6E-01
8E-07
2E-07
NCb
6E-01

2E-01
2E-05
5E-07
NCb
2E-01

2E-01
2E-07
2E-07
NCb
2E-01


KG*
NCC
NCC
NCC
NCC
NCC
NCC

4E-01
4E-07
3E-07
3E-01
Refer to footnotes at end of table.
                                            27

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Table 5. (continued)
Scenario
    Pathway
Deterministic
     risk
 Probabilistic
50th percentile
      risk
 Probabilistic
95th percentile
      risk
Occupational (site-specific #1)
External exposure
Ingestion of soil
Inhalation of dust
Total scenario risk
Occupational (site-specific #2)
External exposure
Ingestion of soil
Inhalation of dust
Total scenario risk
Occupational (future - 30 years)
External exposure
Ingestion of soil
Inhalation of dust
Total scenario risk
Occupational (future - 100 years)
External exposure
Ingestion of soil
Inhalation of dust
Total scenario risk

4E-03
3E-07
6E-09
4E-03a

6E-04
6E-08
9E-10
6E-048

1E-01
1E-05
2E-07
lE-01a

3E-02
2E-06
2E-07
3E-02"

2E-03
2E-09
NCd
2E-03

3E-04
3E-10
NCd
3E-04

4E-02
4E-08
5E-08
4E-02

9E-03
8E-09
5E-08
9E-03

1E-02
5E-09
NCd
1E-02

2E-03
9E-10
NCd
2E-03

3E-01
2E-07
2E-07
3E-01

6E-02
3E-08
2E-07
6E-02
a. Cesium-137 (plus barium-137m) is the primary contributing radionuclide.
b. A probabilistic risk assessment was not performed for the groundwater pathway due to its small contribution to total risk
  and to the absence of published probability distribution functions for input parameters.
c. A probabilistic risk assessment was not performed for the subsistence farmer scenario due to the absence of published
  probability distribution functions for input parameters.
d. A probabilistic risk assessment was not performed due to its small contribution to total risk.
NC = Not calculated.
                                                    28

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 Table 6.  Summary of risks for the potential exposure scenarios and pathways at BORAX-I.
Scenario
Pathway
Residential (30-year, intrusive)
External exposure
Ingestion of soil
Inhalation of dust
Ingestion of groundwater
Total scenario risk
Residential (30-year, nonintrusive)
External exposure
Ingestion of soil
Inhalation of dust
Ingestion of groundwater
Total scenario risk
Residential (100- year, intrusive)
External exposure
Ingestion of soil
Inhalation of dust
Ingestion of groundwater
Total scenario risk
Residential (100-year, nonintrusive)
External exposure
Ingestion of soil
Inhalation of dust
Ingestion of groundwater
Total scenario risk
Subsistence farmer (100-years)
(water independent pathways)
External exposure
Ingestion of soil
Inhalation of dust
Ingestion of plants
Ingestion of meat
Ingestion of milk
Total scenario risk
Occupational (current)
External exposure
Ingestion of soil
Inhalation of dust
Total scenario risk
Deterministic
risk

3E-02
7E-05
9E-07
3E-06
3E-02a

3E-02
3E-05
8E-07
3E-06
3E-028

7E-03
3E-05
9E-07
3E-06
7E-03*

7E-03
8E-06
8E-07
3E-06
7E-038


5E-03
2E-06
4E-06
1E-04
1E-04
4E-05
6E-03a

1E-02
2E-05
5E-07
1E-028
Probabilistic
50th percentile
risk

7E-03
3E-06
2E-07
NCb
7E-03

7E-03
4E-09
5E-09
NCb
7E-03

1E-03
1E-06
2E-07
NCb
1E-03

IE-03
2E-09
5E-09
NCb
IE-03


NCC
NCC
NCC
NCC
. NCC
NCC
NCC

4E-03
1E-09
4E-09
4E-03
Probabilistic
95th percentile
risk

5E-02
8E-06
1E-06
NCb
5E-02

5E-02
1E-08
5E-08
NCb
5E-02

1E-02
4E-06
1E-06
NCb
1E-02

1E-02
1E-08
5E-08
NCb
1E-02


NCC
NCC
NCC
NCC
NCC
NCC
NCC

3E-02
4E-09
3E-08
3E-02
Refer to footnotes at end of table.
                                             29

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 Table 6.  (continued)
Scenario
Pathway
Occupational (site-specific #1)
External exposure
Ingestion of soil
Inhalation of dust
Total scenario risk
Occupational (site-specific #2)
External exposure
Ingestion of soil
Inhalation of dust
Total scenario risk
Occupational (future - 30 years)
External exposure
Ingestion of soil
Inhalation of dust
Total scenario risk
Occupational (future - 100 years)
External exposure
Ingestion of soil
Inhalation of dust
Total scenario risk
Deterministic
risk
2E-04
2E-07
7E-09
2E-04a
3E-05
4E-08
1E-09
3E-058
7E-03
8E-06
5E-07
7E-038
IE-OS
2E-06
5E-07
1E-038
Probabilistic
50th percentile
risk
9E-05
1E-11
NCd
9E-05
2E-05
2E-12
NCd
2E-05
2E-03
6E-10
4E-09
2E-03
5E-04
3E-10
4E-09
5E-04
Probabilistic
95th percentile
risk
5E-04
4E-11
NCd
5E-04
8E-05
6E-12
NO1
8E-05
2E-02
3E-09
4E-08
2E-02
3E-03
2E-09
4E-08
3E-03
a. Cesium-137 (plus barium-137m) is the primary contributing radionuclide.
b. A probabilistic risk assessment was not performed for the groundwater pathway due to its small contribution to total risk
  and to the absence of published probability distribution functions for input parameters.
c. A probabilistic risk assessment was not performed for the subsistence farmer scenario due to the absence of published
  probability distribution functions for input parameters.
d. A probabilistic risk assessment was not performed due to its small contribution to total risk.
NC = Not calculated.
                                                      30

-------
•Q^ 1E+OO —
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o

lE-oe -
£ 1E'1°-
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groundwater

-•• 1E*00 — ,-
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^ 'E*«° — .
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mer Ri



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"• External Ingestion inhalation Ingestion Ingestion Ingestion
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Refer to notes at end of figure
Figure 6. Graphical summary of risk for SL-1.
                                                     31

-------
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SL-1 Occupational (current) Risk CD Deterministic
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~ External exposure Ingestion of soil Inhalation of dust
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b.  The 95th percentile is the reasonable maximum exposure individual risk.

Figures,  (continued)
                                                   32

-------
•0* 1E+00 —
CD
a IE-OJ -
.c
1E-06 -
^ 1E-10 —
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BORAX-I Residential Risk (30-year, intrusive) a D*t.r™r,«tic
,— l~~l 50th fwrcintil* *
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exposure of soil of dust or plants of meat of milk
Refer to notes at end of figure
Figure 7. Graphical summary of risk for BORAX-I.
                                                  33

-------
-J- 1£tOO —
^
3 1E-02
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°- E " External exposure Ingestion of soil Inhalation of dust
a. The 50th percentile is the average individual risk.
b. The 95th percentile is the reasonable maximum exposure individual risk.

 Figure?, (continued)
                                                    34

-------
                                           Residential (current)
1E+00

 1E-02
 5 1E-04
 1E-06
i

 1E-10-

 1E-12-
                                                      9E-2
3E-2
2E-2
                                                                                        2E-2
                                                                                     \
                   National          National
              Natural Background  Natural Background
                (without radon)       (with radon)
                                                   Highest     Local
                                                   Reading   Background
                                                        SL-1
                Highest    Local
                Reading  Background
                   BORAX-I
Figure 8. Graphical summary of external exposure risk based on measured radiological fields and natural background, SL-1,
         and BORAX-I.

    The residential risk (30-year duration) estimated from radiological field measurements at the SL-1
burial ground, 9E-02, is only slightly higher than the risk due to the local background of 3E-02. At
BORAX-I, the risk based on radiological field measurements is equal to local background (2E-02) and
is only slightly higher than the national average natural background, which ranges from 2E-03 to
6E-03.

6.1.5 Uncertainty
    Risk assessments are subject to uncertainty from assumptions about inventory estimates, fate and
transport estimation, exposure estimation, and radiotoxicity data. Uncertainty was addressed by using
health-protective assumptions that systematically overstate the magnitude of health risks.  This process
bounds the plausible upper limits of risk and facilitates an informed risk management decision. Table 7
is a summary of risk assessment assumptions and associated uncertainties.

    In addition to uncertainty directly associated with the baseline risk assessment, two other issues
were considered. The first was estimation of risk associated with the radiological field actually mea-
sured at the sites to evaluate the effectiveness of the soil shielding currently on the sites (the baseline
risk assessment requires exposure of the receptor directly to the waste).  The second issue was explored
as a result of public comment received on the proposed plan and involved estimating the soil concentra-
tion of uranium-235 based on the quantity of unrecovered fuel.
                                               35

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 Table 7. Summary of risk assessment assumptions and associated uncertainties.
 Assumption
 Description of uncertainty
 Effect of uncertainty on
 risk estimates
 Soil sample analytical results
 are representative of surface
 contamination.
 Many samples at both sites were collected
 from hot spots, as opposed to a strictly
 random sampling strategy. Concentrations
 based on the 95% upper confidence limit
 of these biased results were assumed uniformly
 distributed throughout surface soil.
Computer-modeled radionuclide
inventories (curies) converted
to subsurface concentrations of
radionuclides (pCi/g) are
representative of subsurface
contamination.
Radionuclide inventories were assumed uniformly
distributed throughout the reported volumes at a
material density of 1.5 g/cm-*.
 Results in higher
 estimated concentrations
 in surface soils and thus
 increased risk.  (Note that
 Operable Unit 5-05 surface
 soils were found to not
 present an unacceptable
 risk subsequent to the base-
 line risk assessment in the
 remedial investigation.)

 The actual nature and
 density of buried materials
 is not homogeneous.  Areas
 of both higher and lower
 concentrations (and thus
 risk) within the waste are
 expected.
Modeled inventories reduced by   The reduced quantities are upper-bound estimates   Results in higher estimated
percent of uranium-235 recovered  of inventories originally deposited on each site.      concentrations in the sub
are representative of actual                                                       surface and thus increased
concentrations.                                                                  risk.
No migration of contaminants has  Maximizes concentrations (no dilution) and
occurred.                        minimizes volume.
Significant quantities of
nonradioactive contaminants are
not present at either site.
If any nonradioactive contaminants are present,
they would represent an insignificant contribution
 to the total risk at each site.
Modeled receptor is in direct      Shielding provided by existing soil cover is
contact with the surface or        excluded from consideration; the EPA-default time
subsurface contamination for time  and duration of exposure values  are formulated
periods specified in the remedial   for sensitive individuals.
investigation report

Groundwater modeling parameters Parameters and assumptions were selected to
and assumptions generic to the     maximize concentrations of contaminants in the
INEL are adequate to model       groundwater.
groundwater impacts.
Results in higher estimated
concentrations in the sub-
surface and thus increased
risk.

May underestimate risk
slightly.


Results in substantially
higher exposure
values for all receptors,
and thus higher risks.


Results in overestimation of
concentrations in aquifer
and minimizes vadose zone
travel times, resulting in
higher estimated risk.
                                                   36

-------
    The uncertainties related to the measurement of radiological data in the field can lead to an under-
or over-estimation of risk.  Field measurements are accurate at the time and location the reading is
taken. However, factors such as detection limits, correlation of field measurements to specific radionu-
clide concentrations, and perturbations resulting from radioactive fragments or particles add significant
uncertainty to these  risk estimates.

    To address remarks received during the public comment period, hypothetical soil concentrations of
uranium-235 were estimated for the surface soil at BORAX-I  using the assumption that the entire 3.7
kg of uranium-235 unrecovered at the site was uniformly distributed through two soil volumes. The
first, 84,000 cubic feet (2,400 m3) was based on the extent of  gravel-covered area and a depth of one
foot.  A second volume, 14,700 cubic feet (416 m3) by one  foot deep, was based on the portion of the
gravel-covered area  which had a radiological field greater than 0.02 mR/hour during a survey conduct-
ed in 1980.  Concentrations resulting from these calculations were 2.2 pCi/g (1 mg uranium-235/kg
soil) and 13 pCi/g (6 mg uranium-235/kg soil). Although, these estimates were developed under the
assumption that the entire 3.7 kg of uranium-235 was distributed in the surface soil, historical docu-
mentation indicates that some of the fuel remaining at the site was buried in the reactor structure foun-
dation.  In the risk assessment, the 95% upper confidence limit for uranium-235 (68.6 pCi/g), based on
analytical results of biased samples, was used to represent surface soil concentrations. This concentra-
tion is much higher than either 2.2 or 13 pCi/g, demonstrating that use of the 95% upper confidence
limit of biased sampling can result in over-estimation of actual soil concentrations, and therefore over-
estimation of the risk.

6.1.6 Conclusions
    An inspection of the risk values shows several important facets of the investigation:
    •   At the SL-1 burial ground, scenario total risks range from 6E-04 to 5E-01.  At BORAX-I the
       scenario risks range from 3E-05 to 3E-02. The risks are dominated by cesium-137 plus its
       daughter barium-137m in the external exposure pathway for both sites.
    •   The risks due to external exposures estimated by deterministic  or probabilistic methods are all
       greater than 1E-06, and in nearly all scenarios, greater  than 1E-04; the only exception was the
       occupational  site-specific #2 scenario for BORAX-I. Values greater than 1E-04 are considered
       indicative of  conditions that may pose a threat to human health and the environment if not
       addressed by a response action.
    •   The risks attributable to soil ingestion for all radionuclides are generally one or more orders of
       magnitude lower than the risks from external exposure and considered a secondary concern;
       however, for  the residential intrusion scenarios at SL-1, the risk from the soil ingestion  pathway
       exceeds 1E-04.
    •   The risks of soil inhalation and groundwater ingestion  for all scenarios are less than 1E-05 and
       generally less than 1E-06, and thus negligible.
    •   Decay of cesium-137 (plus its progeny) will result in a decrease of risk through time at both
       sites. After about 400 years, the risk will reach 1E-04  at SL-1; after 320 years, the risk at

                                             37

-------
       BORAX-I will be dominated by the long-lived uranium-235 in the external exposure pathway,
       and the risk will not drop below 2E-04.
    •  The external radiation exposure risks estimated using deterministic and probabilistic methods
       dominate the total risk. Although this calculated upper limit of the risk notably exceeds the
       1E-04 risk value, the external exposure risks estimated from radiological field measurements
       were not much greater than the risk due to background radiation.  The primary difference is that
       the baseline risk assessment was based on the assumption that the individual is exposed directly
       to the waste; that is, the dose that the individual receives is not adjusted to account for the
       shielding provided by the soil cover. The risk estimated from the field measurements was based
       on the actual measured dose that an individual at the surface receives.
    •  Although Operable Unit 5-05 surface soils were evaluated in the baseline risk assessment pre-
       sented in the remedial investigation/feasibility study report and summarized in this section, a
       subsequent determination found the surface soils do not present an unacceptable risk to human
       health or the environment (see Section  11.1).
    The main contributor to the deterministic and probabilistic risk is from external exposure to
cesium-137 plus its daughter barium-137m. All other contributions to the total risk are very small, usu-
ally two, three, or more orders of magnitude below the risk due to external exposure to ionizing radia-
tion and generally below the acceptable risk level of 1E-04.

                                6.2 Ecological Concerns
    The ecological assessment of the SL-1  and BORAX-I burial grounds is a qualitative evaluation of
the potential effects of the sites on plants and animals other than people and domesticated species.  A
quantitative ecological assessment is planned in conjunction with the ENEL-wide comprehensive reme-
dial investigation/feasibility study tentatively scheduled for 1998. There are no critical or sensitive
habitats on or nearby the burial grounds, and no endangered species or habitats of endangered species
are known to exist on either site.  Based on the present contaminant and ecological information and the
qualitative eco-evaluation performed for this Record of Decision, the preferred alternative remedial
action presented herein will serve to further reduce  the ecological risks posed by these sites. It is
unlikely the 1998 INEL-wide comprehensive remedial investigation/feasibility study quantitative eco-
logical assessment will result in the need for any additional actions at these sites.

6.2.1 Species of Concern
    The only federally listed endangered species known to frequent the INEL is the peregrine falcon.
The status of the bald eagle in the lower 48 United  States was changed from endangered to threatened
in July 1995.  Several  other species observed on the INEL are the focus of varying levels of concern by
either federal or state agencies. Animal and avian species include the ferruginous hawk, the northern
goshawk, the sharp-tailed grouse, the loggerhead shrike, the Townsend's big-eared bat, the pygmy rab-
bit, the gyrfalcon, the boreal owl, the flammulated owl, the Swainson's hawk, the merlin, and the bur-
rowing owl.  Plant species classified as sensitive include Lemhi milkvetch, plains milkvetch, wing-seed
evening primrose, nipple cactus, and oxytheca.
                                             38

-------
 6.2.2  Exposure Assessment
    Three potential routes of exposure were identified for terrestrial and avian species:  ingestion of
 soil, vegetation, or prey; inhalation of fugitive dust; and external exposure to radiation. Ingestion of
 contaminated water was not considered because there are no surface-water features on either burial
 ground and because groundwater is not accessible to ecological receptors.  For plants, the uptake of
 contaminants through roots systems was considered.

    The amount of exposure is directly related to the amount of time spent and the fraction of diet taken
 on the sites.  Therefore exposures are greatest for permanent ecological residents, particularly plants and
 small burrowing animals. The small size of the burial grounds minimizes the exposures received by
 migratory species, which include most avian and large mammal species that  inhabit the INEL.

 6.2.3  Risk Characterization
    The contaminants of concern at the burial grounds consist of radionuclide-contaminated soil and
 debris, most of which is buried beneath a minimum of 2 feet (0.6 m) of soil.  Both sites are relatively
 small.  Some amounts of contamination may be brought to the surface through plant uptake and bur-
 rowing animals and insects, be ingested by herbivores and animals who take prey from the sites, and
 enter the food web. Individuals representing a small portion of the total population of burrowing and
 ground-dwelling animals may also receive direct exposures. However, risks due to these exposures
 would be limited to a small number of individual ecological receptors and would have little impact on
 total populations.  As a result, the potential for risk to ecological receptors is very small. In addition,
 the inaccessibility of contamination supports the conclusion that the sites do not present a significant
 risk to plant and animal life.

   The small areas of the sites will not support sizeable populations relative to the area and popula-
 tions of the entire INEL. The potential for cumulative effects  throughout each waste area group and
 INEL-wide are of much greater concern than the effects from  the individual burial grounds. These
 issues will be addressed in the comprehensive remedial investigation/feasibility studies for each waste
 area group and for the entire ENEL.

                                 6.3  Basis for Response

   Actual or threatened releases of contaminants from these burial grounds, if not addressed by imple-
 menting the response action selected in this Record of Decision, present a potential threat to public
health, welfare, or the environment.

   The results of the baseline risk assessment indicate that unacceptable risk exists at both burial
grounds. The primary risk at both sites is from external exposure to cesium-137  and its daughter bari-
um-137m.  Decay of cesium-137 (plus its daughter) will result in a decrease of risk to acceptable levels
after about 400 years at SL-1, and after 320 years  at BORAX-I. Risk at both sites results from direct
exposure to the  contaminants. The shielding and control of intrusion can be accomplished through
construction of a long-term engineered cap at each site designed to contain the radionuclides as they
decay with time.
                                              39

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    The risk to ecological receptors at both sites is associated with intrusion into the wastes. This risk
 will decrease through time as the radionuclides decay.  Long-term engineered caps can inhibit intrusion
 by plant roots, insects, and burrowing animals.


                             7. Description of Alternatives

                         7.1  Remedial Action Objectives and
               Applicable or Relevant and Appropriate Requirements
    The description of alternatives includes discussion of how remediation goals are satisfied by the
 actions undertaken.  Similarly, the descriptions explain how compliance with federal and state environ-
 mental laws is achieved.  The remedial action objectives and environmental laws associated with the
 alternatives considered in the remedial investigation/feasibility study for the SL-1 and BORAX-I burial
 grounds are summarized  below to support the description of alternatives.

 7.1.1  Remedial Action Objectives
    As part of the remedial investigation/feasibility study process, remedial action objectives were
 developed in accordance  with the National Contingency Plan and EPA guidance. The intent of the
 remedial action objectives is to set goals for protecting human health and  the environment.  The goals
 are  designed specifically  to mitigate the potential adverse effects associated with the burial grounds.

    Results of the remedial investigation and baseline risk assessment indicate that exposure to pene-
 trating radiation from contaminated soils and materials within the burial grounds presents the most sig-
 nificant future risk to human health. Therefore, the primary remedial action objectives and the focus of
 the  remedial action alternative  development  are to inhibit exposure to radioactive materials.  Remedial
 action objectives established for protection of human health are:

    •   Inhibit exposure to radioactive materials that would result in a total excess cancer risk (for all
       contaminants) of greater than  1 in 10,000 to 1 in 1,000,000 (1E-04 to 1E-06)
    •   Inhibit ingestion of radioactive materials that would result in a total excess cancer risk  (for  all
       contaminants) of greater than  1 in 10,000 to 1 in 1,000,000 (1E-04 to 1E-06)
    •   Inhibit inhalation  of suspended radioactive materials that would result in a total excess cancer
       risk (for all contaminants) of greater  than 1 in 10,000 to 1 in 1,000,000 (1E-04 to 1E-06)
    •   Inhibit degradation of the burial  grounds that could result in exposure of buried wastes or
       migration of contaminants to the surface that would pose a total excess cancer risk (for all cont-
       aminants) of greater than 1 in  10,000 to 1 in 1,000,000 (1E-04 to 1E-06).
   The remedial action objective for  protection of the environment focuses on preservation of the  local
ecology by inhibiting the potential for contaminant migration. The remedial action objective estab-
lished for protection of the environment is:

    •   Inhibit adverse effects to resident species from exposure to contaminants at the burial grounds.
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 7.1.2 Applicable or Relevant and Appropriate Requirements
    CERCLA requires that remedial actions comply with federal and state laws that are applicable to
 the action being taken. Remedial actions must also comply with the requirements of laws and regula-
 tions that are not directly applicable but are relevant and appropriate; in other words, the requirements
 pertain to situations sufficiently similar to those encountered at a CERCLA site so that their use is
 well-suited to the site.  Combined, these are referred to as applicable or relevant and appropriate
 requirements (ARARs). State ARARs are limited to those requirements that are (a) promulgated, (b)
 uniformly applied, and (c) are more stringent than federal requirements. Compliance with ARARs
 requires evaluation of the remedial alternatives for compliance with chemical-, location-, and action-
 specific ARARs or justification for  a waiver.

    During the remedial investigation/feasibility study for SL-1 and BORAX-I, ARARs were specified
 for the remedial action alternatives under consideration.  Potential ARARs initially identified were
 screened on the basis of review by the DOE-ID, the EPA, and the IDHW. Table 8 provides a summary
 of the ARARs for the three alternatives considered. These regulations focus on protection of the public
 from radiation and control of emissions that may result from any remediation activities. As ARARs,
 these regulations govern potential radionuclide emissions and dust-generating activities (such as exca-
 vation, earth-moving, and heavy-equipment operation). Although DOE orders are not ARARs, estab-
 lished DOE orders would be considered to ensure radiation protection for the environment and the pub-
 lic. Such DOE orders are identified as "To-Be-Considered" (TBC) criteria. Currently no EPA or State
 of Idaho regulations exist that establish cleanup levels for radionuclide contaminants in soil. Based on
 the contaminants of concern  at  SL-1 and BORAX-I, the location of the burial grounds, and the remedi-
 al actions evaluated, no other ARARs were identified.

Table 8. Summary of ARARs and criteria to be considered for alternatives.
                                                   Alternative  1  Alternative 2  Alternative 3
Statute               Regulations                    No Action   Containment    Removal
NESHAP    National Emission Standards for               NA           NA          A
            Radionuclide Emissions Other than
            Radon from DOE Facilities (40 CFR §61.90)
IDAPA      Idaho Rules for Control of Fugitive Dust        NA            A          A
            (IDAPA 16.01.01.650  and .651)
IDAPA      Idaho Rules for Toxic Air Pollutants            NA           NA          A
            (IDAPA 16.01.01.585  and .586)
            DOE Order 5400.5, "Radiation Protection of    TBC         TBC        TBC
            the Public and Environment"
            DOE Order 5820.2A, "Radioactive Waste       TBC         TBC        TBC
            Management"
A = Applicable; NA = Not applicable or relevant and appropriate; R = Relevant and appropriate; TBC = To be considered
                                            41

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                              7.2 Summary of Alternatives
    The three types of alternatives submitted to detailed analysis include:

    Alternative 1:     No action

    Alternative 2:     Containment by capping with an engineered long-term barrier comprised
                    primarily of natural materials

    Alternative 3:     Removal by conventional excavation with disposal at the Radioactive Waste
                    Management Complex.

    The no action alternative and the two alternatives that passed the screening criteria are described
below. Remedial action at BORAX-I is expected to include management of contaminated surface soils.
Surface soils presenting a potential human health excess risk of over 1 in 10,000 will be included in the
remedial action. Action levels for the radionuclides of concern in BORAX-I soils are based on the
Remedial Investigation/Feasibility Study for Operable Unit 10-06 (Radionuclide-Contaminated Soils at
the INEL) and are identified as 16.7 pCi/g for cesium-137, 10.8 pCi/g for strontium-90, and 13.2 pCi/g
for uranium-235. These activity concentrations correspond to a 1 in 10,000 risk level based on the
external exposure and ingestion pathways and a residential scenario beginning in 100-years. Costs pre-
sented for remedial actions at BORAX-I are based on the assumption that all potentially contaminated
surface soils will be included in the remedial action.  A surface area as large as 84,000 square feet
(7,800 m^) would require management as part of the remedial action at BORAX-I. As presented in the
proposed plan, remedial action at the SL-1 operable unit may have also required management of poten-
tially contaminated surface soils. An assessment of those soils has since been completed that supports
a no action decision for the surface soils within Operable Unit  5-05 outside of the exclusion fence.
Section  11 contains more details regarding this assessment.

7.2.1 No Action
    Under Alternative 1, no attempt would be made to contain, treat in place, or remove contaminated
materials.  Instead, environmental monitoring would be performed to assess contaminant miration
from the burial grounds.  Environmental monitoring would consist of those methods used to identify
contaminant migration within environmental media (air, groundwater, and soil) and to identify the
exposure resulting from those contaminated media. Monitoring results would be used to determine the
need for any future remedial actions necessary to protect human health and the environment.
Environmental monitoring would be conducted until future reviews of the remedial action determine
such activities are no longer necessary. There were no ARARs identified for the no action alternative.

    The estimated cost for implementing environmental monitoring for 30 years under this alternative is
$188,000 at SL-1 and $180,000 at BORAX-I.  Environmental monitoring may be required beyond 30
years, however CERCLA guidance specifies costing such activities for only 30 years.

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    To the extent practicable, environmental monitoring activities would be performed under WAG-
 wide and INEL-wide comprehensive monitoring programs.  Radiological surveys would be performed
 at both SL-1 and BORAX-I as part of this remedial action until WAG-wide comprehensive environ-
 mental monitoring programs are in place.  Groundwater monitoring needs would be identified in the
 WAG 5 Comprehensive RI/FS and the WAG 10 Comprehensive RI/FS (which encompasses WAG 6).
 Air monitoring at both site« would be conducted as part of the INEL-wide air monitoring program.

 7.2.2  Containment
    Alternative 2 is a containment action that consists of installing a long-term engineered barrier (cap)
 over a burial site to provide shielding from penetrating radiation, to inhibit contaminant migration, and
 to limit intrusion.  Barrier technology is currently in use at several waste sites to provide long-term iso-
 lation of radioactive wastes that are disposed of in place, as is the case for both burial grounds. The
 cap can be designed for longevity and would be of sufficient thickness to provide a shield from pene-
 trating radiation, inhibit intrusion by burrowing animals and insects into the waste, and discourage
 human intrusion. Contaminant migration would be inhibited by reducing  erosion by wind and water.

    The barrier would be designed to provide shielding from penetrating radiation for at least 400 years at
 SL-1 and 320 years at BORAX-I.  A multiple-layer cap comprised primarily of natural materials would be
 designed during the remedial design phase of the remedial action. Cap layers would likely consist of a
 combination of sand, gravel, silt, basalt, cobbles, or native soil. Construction details for the engineered
 barrier would be identified during the remedial design phase. The barrier design would be based on site-
 specific characteristics and conditions at the INEL such that maintenance requirements are minimized.
 Site-specific considerations, such as annual precipitation, frost depth, and anticipated soil erosion, would
 be used to design the optimum barrier configuration for application at the SL-1 and BORAX-I burial
 grounds during the remedial action phase.  Each cap system would also include surface-water diversion
 controls to direct runoff away from the  burial grounds.

    The capping system would be combined with institutional controls consisting of access and land
 use restrictions to prevent intrusion into the SL-1 and BORAX-I burial grounds. The DOE would be
 responsible for establishing and maintaining land use and access restrictions for at least 100 years.
 Access restrictions in the form of fences, warning signs, and permanent markers would be used to
 determine unauthorized entry into the burial grounds.  Institutional controls would include placing writ-
 ten notification of the remedial action in the facility land use master plan;  the notification would pro-
hibit any activities that would interfere with the remedial activity. A copy of the notification would be
 given to the Bureau of Land Management, together with a request that a similar notification be placed
in the Bureau of Land Management property management records.  The DOE would provide EPA and
IDHW with written verification that notification, including Bureau of Land Management notification,
have been fully implemented.

    Cap integrity monitoring and radiological survey programs would be established to verify the con-
tinued functionality of the containment  systems and provide  early detection of potential contaminant
migration. Cap integrity monitoring for cracks, erosion, and other observable degradation would be
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 conducted to identify maintenance requirements. Institutional controls and monitoring requirements
 would be the responsibility of the DOE and would be evaluated for adequacy, effectiveness, and neces-
 sity during each five-year review of the remedial actions.

    The area requiring containment at SL-1 is the region extending from the trench to pit 1 in Figure 2.
 The area requiring containment at BORAX-I is based on the assumption that consolidation of all conta-
 minated surface soil is necessary. The minimum area requiring containment at BORAX-I is the 100-
 by 100-foot (30- by 30-m) fenced area of the burial ground, or 10,000 square feet (929 m2).  The maxi-
 mum area of containment required at BORAX-I is based on the assumption that the entire 84,000
 square foot (7,800 m2) area of contaminated surface soil would require containment. Although protec-
 tive covers over this entire area are feasible, consolidation of contaminated surface soil to a location
 near the existing buried wastes is proposed. Consolidation of contaminated surface  soil would ensure
 that the size of a protective cover is limited to the area containing the majority of contamination
 (e.g.,  the reactor foundation).

    The ARAR identified for this alternative is the Idaho Rules for Control of Fugitive Dust
 (IDAPA 16.01.01.650 and  .651). This ARAR would be met during soil consolidation activities at
 BORAX-I and construction of a barrier at either site by application of appropriate engineering controls
 to minimize generation of airborne contamination and dust.

    The estimated cost of Alternative 2 is $1.9 million at  SL-1 and $1.5 million at BORAX-I.  These
 costs are based on refinements to the estimates presented in the proposed plan for Alternative 2. The
 primary refinements include a cap design specific to the INEL and elimination of groundwater monitor-
 ing requirements.  "The cap  design is based on research performed at the INEL by the Environmental
 Science and Research Foundation. Environmental monitoring has been specified by the agencies to
 consist of radiological surveys. Groundwater monitoring costs have not been included because ground-
 water monitoring needs will be determined by the WAG 5 Comprehensive  RI/FS for WAG 5 as a whole
 and the WAG 10 Comprehensive RI/FS for WAG 6. Responsibility for radiological surveys at SL-1 will
be assumed by the WAG  5 Comprehensive RI/FS once the comprehensive  program is  in place.  Similarly,
responsibility for radiological surveys at BORAX-I will be assumed by the WAG 10-04 Comprehensive
RI/FS once the comprehensive program is in place. The cost estimates include 30 years of radiological
 surveys at SL-1 and BORAX-I.  (Air monitoring at both sites would be conducted as part of the ENEL-
wide air monitoring program to eliminate that cost component from this remedial action.)

    Direct costs for equipment and construction are approximately $0.90 million at SL-1 and $0.61
million at BORAX-I (including soil consolidation). Indirect costs for engineering design and manage-
ment,  construction management, and contractor overhead and profit are approximately $0.47 million at
SL-1 and $0.45 million at BORAX-I.  A contingency cost to account for the conceptual level of design
for Alternative 2 is approximately $0.27 million at SL-1 and $0.18 million at BORAX-I.  Net present
value cost to perform post-closure monitoring and  maintenance activities for 30 years  are approximately
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 $0.33 million at SL-1 and $0.21 million at BORAX-I. Monitoring and maintenance may be required
 beyond 30 years, however CERCLA guidance specifies costing such activities for no more than 30 years.

 7.2.3  Removal and Disposal
    Alternative 3 is the complete removal of all contaminated materials from the burial grounds using
 conventional excavation techniques, with cleanup levels established on the basis of excess risk at the
 INEL. Conventional excavation techniques utilize commercially available earth-moving equipment.

    The volume of contaminated media at the SL-1 is approximately 265,182 cubic  feet (7,509 m3).
 The total volume of contaminated media at the BORAX-I is approximately 93,421 cubic feet
 (2,645 m3).  These estimates are based on the volumes of buried waste, backfill, and potentially conta-
 minated surface soils at BORAX-I.  Once removed, contaminated materials would be packaged and
 transported to the Radioactive Waste Management Complex for disposal.

    Following the removal of contaminated soil and solid waste, the excavated area would be backfilled
 with clean fill material and compacted to prevent future subsidence or settling.  A layer of topsoil
 would be placed over the compacted backfill, contoured to match the surrounding landscape, and seed-
 ed with an appropriate mixture of native grasses and shrubs to facilitate revegetation.

    The ARARs identified for this alternative include the National Emissions Standards for
 Radionuclide Emissions Other than Radon  from DOE Facilities (40 CFR §61.90), Idaho Rules for
 Toxic Air Pollutants  (IDAPA 16.01.01.585  and .586), and Idaho Rules for Control of Fugitive Dust
 (IDAPA 16.01.01.650 and .651).  All three  ARARs would be met by conducting excavation activities
 within an enclosed structure fitted with a filtered ventilation system and by implementing dust-suppres-
 sion measures.

    The estimated costs of Alternative 3 are approximately  $68.9 million at SL-1 and $20.5 million at
 BORAX-I. The estimated cost for SL-1 is  based on the no action decision for soils  outside of the
 600- by 300-foot (182.9- by 91.4-m) exclusion fence but inside the boundary of Operable Unit 5-05.
 The lower end of the cost range presented in the proposed plan for Alternative 3 at SL-1 reflects this
 situation.  The estimated cost for BORAX-I is based on the anticipated need to include up to 84,000
 square feet (7,800 m2) of contaminated surface soil in the remedial action. The upper  end of the cost
 range presented in the proposed plan for Alternative 3 at BORAX-I is representative of this scenario.

    The estimates include an assumption that no additional costs are incurred once the  contaminated
materials are removed from the sites and disposed at the Radioactive Waste Management Complex.
Therefore, post-closure activities such as monitoring are not required.  Direct costs for equipment, con-
struction, and disposal at the Radioactive Waste Management Complex are approximately $34.0 mil-
 lion at SL-1 and $10.1 million at BORAX-I. Indirect costs for engineering design and management,
 construction management, and contractor overhead and profit are approximately $24.7 million at SL-1

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 and $7.4 million at BORAX-I.  The contingency cost to account for the conceptual level of design for
 Alternative 3 is approximately $10.2 million at SL-1 and $3.0 million at BORAX-I.

                8.  Summary of Comparative Analysis of Alternatives
    Each of the three alternatives subjected to the detailed analysis were evaluated against the nine evalu-
 ation criteria identified under CERCLA. The criteria are subdivided into three categories: (a) threshold
 criteria that mandate overall protection of human health and the environment and compliance with
 ARARs; (b) primary balancing criteria that include long- and short-term effectiveness, implementability,
 reduction in toxicity, mobility or volume through treatment, and cost; and (c) modifying criteria that mea-
 sure the acceptability of alternatives to state agencies and the community. The following sections sum-
 marize the evaluations of the three alternatives against the nine evaluation criteria.

                                  8.1  Threshold Criteria
    The remedial alternatives were evaluated in relation to the two threshold criteria: overall protection
 of human health and the environment, and compliance with ARARs.  The selected remedial action
 must meet the threshold criteria. Although the no action alternative does not meet the threshold crite-
 ria, this alternative was used in the detailed analysis as  a baseline against which the other alternatives
 were compared, as directed by EPA guidance.

 8.1.1  Overall Protection of Human Health and the Environment
    This criterion addresses whether a remedy provides adequate protection of human health and the
 environment and describes how risks posed through each exposure pathway are eliminated, reduced, or
 controlled through treatment, engineering controls, or institutional controls.

    Results of the baseline risk assessment indicate that upper limit of exposure risk will decrease to
 below 1 in 10,000 after approximately 400 years at SL-1. This upper limit will further decrease to 3 in
 1,000,000 after approximately 650 years and remain constant thereafter. The upper limit of exposure
risk at BORAX-I will decrease to approximately 2 in 10,000 after 320 years, then remain essentially
 unchanged far into the future.

    Alternative 1 (no action) would not satisfy the criterion of overall protection of human health and
the environment because access to the site and contact with the waste is not prevented.  The contain-
 ment alternative, Alternative 2, would provide overall protection of human health and the environment.
A protective cover would provide shielding from penetrating radiation, limit contaminant migration,
and inhibit inadvertent intrusion into the wastes by humans, insects, and animals. Consolidated surface
 soil at BORAX-I would also be contained beneath the protective cover.  Long-term protection would be
ensured by incorporating design features engineered to last a minimum of 400 years at SL-1 and 320
years at BORAX-I. Alternative 3 (removal by conventional excavation with disposal at the Radioactive
Waste Management Complex) would provide effective long-term protection of human health and the

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 environment but could result in potentially significant short-term exposures for workers removing the
 radionuclide-contaminated wastes during the remedial action.

    Both of the action alternatives would result in a reduction of excess lifetime cancer risk. Alternative 2
 would result in an excess lifetime cancer risk of less than 1 in 1,000,000 for as long as the cap remains
 functional. A cap minimizes  potential risks by shielding, limiting migration of contamination, and inhibit-
 ing intrusion into the waste. Alternative 3, the removal action, would reduce risk by managing contaminat-
 ed materials removed from the burial grounds within an operating radioactive waste disposal facility.

 8.1.2  Compliance with Applicable or Relevant and Appropriate Requirements
    There are no ARARs identified for the no action alternative. The two action alternatives meet the
 identified ARARs through engineering controls and operating procedures.  Section 7.2, Summary of
 Alternatives, discusses the primary ARARs considered in this study. These ARARs focus on control-
 ling exposures to the public and air emissions that may result from remediation activities at the SL-1
 and BORAX-I operable units.

                                  8.2 Balancing  Criteria
    Once an alternative satisfies the threshold criteria, five balancing criteria are used to evaluate other
 aspects of the remedial alternatives and weigh major trade-offs among alternatives. The balancing cri-
 teria are used in refining the  selection of the candidate alternatives for the site. The five balancing cri-
 teria are:  (1) long-term effectiveness and permanence; (2) reduction in toxicity, mobility or volume
 through treatment; (3) short-term effectiveness;  (4) implementability; and (5) cost.

 8.2.1   Long-Term Effectiveness and Permanence
    This criterion evaluates the long-term effectiveness of alternatives in maintaining protection of
 human health and the environment after remedial action objectives have been met.

    Alternative 1 (no action) provides the least possible level of long-term effectiveness and permanence
 because unacceptable risks would remain at both burial grounds.  The long-term effectiveness and perma-
 nence of containment, Alternative 2, depends on the design-life 01 caca protective cover.  As described pre-
 viously, the cover can be designed to last for the period of time required to allow radionuclide decay to
decrease exposure risks to acceptable levels.  Risks at SL-1 will fall below the 1 in  10,000 risk range in
about 400 years.  Risks at BORAX-I will decrease to about 2 in 10,000 in approximately 320 years and
will remain constant, essentially forever, due to the presence of long-lived uranium-235.  The Alternative 3
removal action provides the highest degree of long-term effectiveness and permanence because contami-
nated materials would be completely removed. However, removing and transporting contaminated materi-
als from one place to another  within the INEL (from SL-1  or BORAX-I to the Radioactive Waste
Management Complex) simply transfers the risk from one place to another.
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 8.2.2  Reduction of Toxicity, Mobility, or Volume through Treatment
    This criterion addresses the statutory preference for selecting remedial actions that employ treat-
 ment technologies that permanently reduce toxicity, mobility, or volume of the hazardous substances as
 their principal element. Treatment to reduce the toxicity of radionuclides is presently not feasible;
 therefore none of the remedial alternatives developed for the  burial grounds involve the use of treat-
 ment to reduce the toxicity, mobility, or volume of contaminated materials.

    8.2.3 Short-Term Effectiveness

    Short-term effectiveness addresses the period of time needed to implement remediation methods to
 reduce any adverse impacts on human health and the environment  that may be posed  during the con-
 struction and implementation period until cleanup goals are achieved.

    The short-term effectiveness for any remedial action taken at the burial grounds would be enhanced
 to the maximum extent practicable through adherence to strict health and safety protocols for worker
 protection and use of engineering controls to prevent potential contaminant migration. However, the
 alternative that requires the least amount of disturbance of contaminated materials ranks the highest in
 terms of short-term effectiveness.  As such, Alternative 1 (no action)  provides the highest degree of short-
 term effectiveness because no additional on-site activities are required.  Implementation of Alternative 2
 (containment) would require disturbance to the surface of the burial grounds, however, no contact with
 buried waste would be  involved.  Alternative 2 does require contaminated surface soil at BORAX-I to
 be consolidated near the location of the reactor foundation. Assuming no protective measures were in
 place, workers installing the Alternative 2 cap would receive external exposure to penetrating radiation
 until sufficient construction material (such as soil, sand, and gravel) was placed over the  burial ground to
 provide adequate shielding. Based on  modeling and field measurements, approximately  3 inches  (0.1 m)
 of additional soil placed over the SL-1 burial ground and 9 inches (0.2 m) of additional soil placed over
 the BORAX-I burial ground would reduce external exposures to background radiation levels.
 Consequently, the soil required to form the foundation for a protective cover is likely to reduce external
 exposures to background levels. Alternative 3 (conventional excavation) offers the least short-term effec-
 tiveness due to direct contact with contaminated materials during excavation of the burial grounds and
 transport  to the Radioactive Waste Management Complex.  Short-term effectiveness for Alternatives 2 and
 3 would be equally diminished if surface-soil consolidation is required at BORAX-I.

 8.2.4 Implementability
   The implementability criterion has the following three factors requiring evaluation:  (a) technical
feasibility, (b) administrative feasibility, and (c) the availability of services and materials.  Technical
feasibility requires an evaluation of the ability to construct and operate the technology, the reliability of
the technology, the ease of undertaking additional remedial action (if necessary), and monitoring con-
siderations. The ability to coordinate actions with  other agencies is one factor for evaluating adminis-
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 trative feasibility, and the agencies have demonstrated this ability throughout the project to date. Other
 administrative activities that would be readily implementable include planning, use of administrative
 controls, and personnel training.  In terms of services and materials, an evaluation of the following
 availability factors is required: necessary equipment and personnel, prospective technologies, and
 cover materials.

    Alternative 1 (no action) is the simplest remedial action to implement from a technical perspective
 because environmental monitoring is all that is required. Monitoring would be required until future
 reviews of the remedial action indicate such activities are no longer necessary.  Environmental monitor-
 ing services and equipment are readily available. However, Alternative 1 is administratively unaccept-
 able due to the potential risks to human health and the environment posed by SL-1 and BORAX-I.

    The containment option of Alternative 2 is technically implementable.  Consolidation of contami-
 nated surface soils at BORAX-I would involve standard earth moving equipment to perform excavation
 activities and water spray vehicles for dust suppression.  Construction capabilities for engineered barri-
 ers are commercially available, and such barriers have been used at many similar sites in both private
 industry and at government facilities.  Specialized construction equipment and materials would not be
 required. The engineering required to design and construct a cap meeting the requirements necessary
 to ensure protection of human health and the environment at SL-1 and BORAX-I would be specified
 during the remedial design phase.  The general performance requirements of the cap are established in
 this Record of Decision.

    Alternative 3 (excavation and removal) would be the  most difficult remedial option to implement
 because of the complexity of the remediation process.  Containment of contamination during excava-
 tion and handling contaminated materials removed from  the burial grounds would be required.
 Conventional excavation techniques to perform removal operations are commercially available and
 commonly used for earth moving applications. Administratively this alternative would require signifi-
 cant time and resources to perform environmental assessments, safety analyses, designs, and demon-
 strations prior to initiating any removal activity.

 8.2.5 Cost
    In evaluating project costs, an estimation of the direct and indirect costs in present-worth dollars is
 required. Direct costs include the estimated dollars for equipment, construction, and operation activi-
ties to conduct a remedial action. Indirect costs include the estimated dollars for activities that support
the remedial action (such as construction management, project management, and management reserve).
In accordance with remedial investigation/feasibility study guidance, the costs presented are estimates
 (-30% to +50%). Actual costs will vary based on the final design and detailed cost itemization.

   Table 9 for SL-1 and Table 10 for BORAX-I summarize the estimated costs for each remedial
action alternative. The costs presented are based on a specific  set of assumptions and as those assump-

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 tions change so will the cost estimates. For example, CERCLA guidance specifies monitoring and
 maintenance costs to be estimated for 30 years.  However, these activities may be required beyond 30
 years and as a result may cost significantly more than estimated.

    The cost estimates presented for Alternative  3 (excavation and removal) are based on the proposed
 plan and the remedial investigation/feasibility study prepared for 5T.-1 and BORAV-I. As indicated in
 Section 7.2.1, the estimated cost for no action (Alternative 1) differs from the proposed plan because
 monitoring requirements for the sites have been  refined.

    The cost estimates presented for Alternative  2 (containment) have been revised since the proposed
 plan. As part of the CERCLA process, estimated costs for the selected remedy have been refined based
 on further developments in the level of design detail for Alternative 2.  Estimated costs for Alternative
 2 have been revised based on a cap design specific to the conditions at the INEL and identification of
 specific environmental monitoring requirements  at both sites. The cap design is based on research per-
 formed at the INEL by the Environmental Science and Research Foundation.  Environmental monitor-
 ing has been specified by the agencies to consist of radiological surveys. Groundwater monitoring
 costs have not been included because groundwater monitoring needs will be determined by the WAG 5
 Comprehensive RI/FS for WAG 5 as a whole and the WAG 10 Comprehensive RI/FS for WAG 6.
 Responsibility for radiological surveys at SL-1 will be assumed by the WAG 5 Comprehensive RI/FS
 once the comprehensive program is in place.  Similarly, responsibility for radiological surveys  at
BORAX-I will be assumed by the WAG 10-06 Comprehensive RI/FS once the comprehensive  program
is hi place. The cost estimates included 30 years of radiological surveys at both sites. (Air monitoring
at both sites will be conducted as part of the INEL-wide air monitoring program. Therefore air moni-
toring costs are not included in the estimates.) The estimated costs presented for Alternative 2  reflect
these refinements.
                                             so

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 Table 9.  SL-1 alternative cost estimates.a

Cost Elements
Construction and construction operations"
Post-closure maintenance0
Post-closure monitoring*1
Contingency
Total6
Alternative 1
No Action
NA
NA
150,000
38,000
$188,000
Alternative 2
Containment
$1,368,000
115,000
150,000
337,000
$1,970,000
Alternative 3
Removal
$58,724,000
NA
NA
10,149,000
$68,870,000
a. Costs are for 1995 for Alternatives 1 and 2 and 1994 for Alternative 3.
b. Includes operating costs (net present value) during remedial
action.


c. Net present value assuming 5% interest (net of inflation) for 30 years.
d. Changed from proposed plan to include soil monitoring only. See Section 1 1 .
e. Rounded to ten thousands.
NA = Not applicable (item is not included in the scope for the

alternative).




Table 10. BORAX-I alternative cost estimates.3

Cost Elements
Construction and construction operationsb
Post-closure maintenance0
Post-closure monitoringd
Contingency
Total6
Alternative 1
No Action
NA
NA
144,000
36,000
$180,000
Alternative 2
Containment
$1,058,000
27,000
144,000
225,000
$1,450,000
Alternative 3
Removal
$17,518,000
NA
NA
3,020,000
$20,540,000
a. Costs are for 1995 for Alternatives 1 and 2 and 1994 for Alternative 3.
b. Includes operating costs (net present value) during remedial action.
c. Net present value assuming 5% interest (net of inflation) for 30 years.
d. Changed from proposed plan to include «oil monitoring only. See Section 11.
e. Rounded to ten thousands.
NA = Not applicable (item is not included in the scope for the alternative).
                                     8.3  Modifying Criteria
    Two modifying criteria are used in the final evaluation of remedial alternatives: state acceptance
and community acceptance.  For both of these criteria, the factors that are considered include the ele-
ments of the alternatives that are supported, the elements of the alternatives that are not supported, and
the elements of the alternatives that have strong opposition.
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 8.3.1  State Acceptance
    The EDHW concurs with the selected remedial alternative, containment with an engineered cover
 comprised primarily of native materials.  The IDHW has been involved in the development and review
 of the remedial investigation/feasibility study, the proposed plan, and this Record of Decision.
 Comments received from EDHW were incorporated into these documents, which have been issued with
 IDHW concurrence.

 8.3.2  Community Acceptance
    This assessment evaluates the general community response to the proposed alternatives presented in
 the proposed plan. Specific comments are addressed in the Responsiveness Summary portion of
 Appendix A in this document.

    Nine individuals provided comments on the proposed plan during the public comment period. One
 additional comment was received after the comment period. A total of nineteen comments were
 received.  Public opinion on the preferred alternative, in no particular order, included, but was not lim-
 ited to (a) Alternative 3, Removal, should have been selected; (b) Alternative  2, Containment, was the
 best choice; (c) models for groundwater fate and  transport should be benchmarked and validated before
 proceeding; (d) maximum doses should be compared to maximum dose limits; (e) how were the laws
 addressing disposal of spent fuel,  transuranic wastes, greater-than-Class-C wastes, and low-level wastes
 accounted for; (f) trials regarding  partial cleanup, including ground scraping and removal,  should be
 conducted and considered; (g) future land uses should be considered; (h) results of other capping stud-
 ies  should be used in this evaluation; (i) no further out-of-state shipments of radioactive wastes should
 be allowed to be deposited there; and (j) publications and the expenditures directed toward low-risk
 projects are a total waste of taxpayers' dollars.

    In summary, three commentors favored the preferred alternative, two preferred Alternative 3, and
 the  others either requested additional or clarifying information or provided comments not specifically
 associated with the two sites in question.  The additional information requested appears in the
 Responsiveness Summary in Appendix A.

                                   9.  Selected Remedy
    Based  upon consideration of the requirements of CERCLA, on detailed analysis, and on public com-
 ments, the DOE-ID, the EPA, and the IDHW have selected Alternative 2, Containment, as the most
appropriate remedy for both the SL-1  and BORAX-I burial grounds. The agencies believe that this alter-
native represents the best balance of trade-offs with respect to the evaluation criteria. Alternative 2 pro-
vides overall protection of human health and the environment, complies with ARARs, provides long- and
 short-term effectiveness, is readily  implementable, and is cost-effective.  An engineered barrier can effec-
tively isolate contaminated materials from the accessible environment. Isolation both inhibits migration
of contaminants from the burial grounds and allows time for radioactive decay of the primary contributor,
cesium-137 and progeny, to the overall risk. Engineered barriers can also inhibit biotic and inadvertent
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 human intrusion into the burial grounds. The agencies believe that an engineered cover system can main-
 tain isolation of contaminated materials while the overall risks decrease. Engineered barriers have been
 used extensively for remedial actions involving radionuclide-contaminated wastes.

    Results of the baseline risk assessment indicate that the direct exposure pathway dominates the
 overall risk for both burial grounds.  The primary contributor to this risk at both sites is cesium-137 and
 its progeny. Based on the time required for radionuclide decay to reduce the direct exposure risk to 1
 in 10,000 at SL-1 and 2 in 10,000 at BORAX-I, a protective cover must be effective for approximately
 400 years at SL-1 and for approximately 320 years at BORAX-I.

                          9.1  Description of Selected Remedy
    The selected remedial action for both burial grounds is Alternative 2, containment by capping with
 an engineered long-term barrier comprised primarily of natural materials.  The cover will be designed
 to maintain effective long-term isolation of contaminants. The number and thicknesses of layers
 designed in the cover depend on local climatic and geographic conditions,  including precipitation rate,
 freeze depth, indigenous plant and animal species, and local topography. A 25-foot (7.5-meter) buffer
 zone will be established around the perimeter of the containment structures at each site. Additional
 design considerations will include the engineered lifetime of each cap, a minimum of 400 years at SL-1
 and a minimum of 320 years at BORAX-I, to allow decay of cesium-137 and to reduce exposure risks.
 Surface-water diversion measures, including contouring and grading, will be  used as necessary to direct
 runoff away from the burial grounds  and into nearby, naturally occurring drainage formations. The
 specific cover design for each burial ground will be defined during final remedial design.
   The cover system design will provide:
   •   Shielding from penetrating radiation
   •   A barrier to inhibit biotic and inadvertent human intrusion
   •   Longevity through the predominant use of naturally occurring materials
   •   Resistance to erosion that could expose buried waste and contribute to contaminant migration
   •   Containment of contaminated surface soils which pose an excess risk  greater than  1 in 10,000 at
       BORAX-I
   •   Low maintenance  requirements.
   The capping system will be combined with instititional controls consisting of access and land use
restrictions to discourage  intrusion into the SL-1 and BORAX-I burial grounds. The DOE would be
responsible for establishing and maintaining land use and access restrictions for at  least 100 years.
Access restrictions in the  form of fences, warning signs, and permanent markers would be used to deter
unauthorized entry into the burial grounds.  Institutional controls would include placing written notifi-
cation of the remedial action in the facility land use master plan; the notification will prohibit any
activities that would interfere with the remedial activity.  A copy of the notification, will be given to the

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 Bureau of Land Managment, together with a request that a similar notification be placed in the Bureau
 of Land Management property management records. The DOE will provide EPA and IDHW with writ-
 ten verification that notification, including Bureau of Land Managment notification, have been fully
 implemented.

    Cap integrity monitoring and radiological survey programs will be established to ensure the func-
 tionality of the containment systems and provide early detection of potential contaminant migration.
 These programs will be implemented annually for the first five years following completion of the caps.
 The necessity for continued monitoring will then be reevaluated and defined as determined appropriate
 by the agencies during subsequent five-year reviews. Groundwater monitoring needs at WAG 5 will be
 determined by the WAG 5 Comprehensive RI/FS.  Radiological surveys at SL-1 will be conducted as
 part of this Record of Decision until such time the surveys can be included as part of the environmental
 monitoring program established for the WAG 5 Comprehensive RI/FS. Similarly, groundwater moni-
 toring needs at WAG 6 will be determined during the WAG 10 Comprehensive RI/FS. Radiological
 surveys at BORAX-I will be conducted as part of this Record of Decision until such time the surveys
 can be included as part of the environmental monitoring program established for the WAG 10
 Comprehensive RI/FS.  Air monitoring will be conducted as part of the INEL-wide  air monitoring pro-
 gram. Cap integrity monitoring for cracks, erosion, and any observable degradation will be conducted
 to identify maintenance requirements.  Institutional controls and monitoring requirements will be the
 responsibility of the DOE and will be evaluated for adequacy, effectiveness, and necessity during each
 five-year review of the remedial actions.

   During implementation dust suppression measures such as water sprays will be used to minimize
 dust generation and thereby ensure compliance with ARARs (IDAPA 16.01.01.650 and .651).  Health
 and safety plans will be established to identify training requirements, specify personal protection equip-
 ment requirements, and  define general safe work practices. The remedial design will include measures
 to ensure mitigation of potential contaminant migration during implementation.

   Implementation of the selected remedy at BORAX-I includes consolidation of contaminated surface
 soils which pose an excess risk greater than 1 in 10,000 to a location near the reactor foundation.  Any
 surface soils consolidated will then be isolated beneath the engineered barrier. Action levels for the
radionuclides of concern in BORAX-I surface soils are identified as 16.7 pCi/g for cesium-137, 10.8
pCi/g  for strontium-90, and 13.2  pCi/g for uranium-235.

   Because this remedy will result in wastes remaining on site, five-year reviews of this Record of
Decision and reviews of monitoring data will be conducted. Evaluation will be performed within five
years of the Record of Decision signature and will  be conducted at least every five years thereafter until
such evaluations are determined by the agencies to be no longer necessary. The purpose of these
reviews  is to ensure that the remedy achieves the remedial action objectives set forth in this Record of
Decision and continues to provide adequate protection of human health and the environment.
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                                  9.2  Remediation Goals
    The purpose of this response action is to inhibit potential exposure for human and environmental
 receptors and to minimize the spread of contamination. This will be accomplished by constructing
 long-term covers (caps) and restricting access to the sites.

    Performance standards will be implemented to ensure that the cover system provides protection
 against direct exposure to the wastes at the two sites. The performance standards identified for the con-
 tainment alternative include:

    •  Installation of caps that are designed to remain in existence for at least 400 years at SL-1 and
       320 years at BORAX-I to discourage any individual from inadvertently intruding into the buried
       waste or from contacting the waste at any time after active institutional controls  over the dispos-
       al sites are removed up to the design life of the cap.
    •  Application of maintenance and surface monitoring programs for the containment systems capa-
       ble of providing early warning of releases of radionuclides from the disposal site before they
       leave  the site boundary.
    •  Institution of restrictions limiting land use to industrial applications for at least 100 years.
    •  Implementation of surface water controls to direct surface water away from the disposed
       wastes.
    •  Elimination, to the extent practicable, of the  need for ongoing active maintenance of the dispos-
       al sites following closure so that only surveillance, monitoring,  or minor custodial care are
       required.
    •  Placement of adequate cover to inhibit erosion by natural processes for the specified design
       lives of the caps.
    •  Incorporation of features to inhibit biotic intrusion into the waste disposal pits and trench at the
       SL-1 burial ground.
    The inspection and maintenance of the cover system will be conducted concurrent with the radiolog-
ical survey program.  Implementation of the maintenance and survey programs will ensure protection of
human health and the environment from any unacceptable risks. These  programs will be implemented
annually for the first five years following completion of the caps.  The necessity for continued monitor-
ing will then be reevaluated and defined as determined appropriate by the agencies during subsequent
five-year reviews.
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                9.3  Estimated Cost Details for the Selected Remedy
   A summary of the costs for each of the remedial action alternatives evaluated was presented in
Tables 9 and 10.  As noted in Section 8.2.5, additional design details for the engineered barrier and
environmental monitoring requirements have enabled subsequent refinements in the original cost esti-
mates for Alternative 2 (containment). Tables  11 and 12 provide detailed breakdowns of the estimated
costs for the selected remedy, based on refinements in the costs presented previously in the proposed
plan.  Post-closure costs for maintenance and monitoring of the sites are net present value  dollars for
1994. These costs are calculated based on a 5  percent interest rate (net of inflation).
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Table 11. SL-1 selected remedy detailed cost estimate.3
Cost Elements                                                Estimated Cost
Construction
    Mobilize/demobilize cap subcontractor                       $   95,000
    Construction of cap                                            543,000
    Subsidence prevention                                           22,000
    Surface water control                                           51,000
    Air monitoring                                                  50,000
    Miscellaneous                                                 141,000
    Construction management                                      234,000
    Engineering design and inspection                               111,000
    Contractor overhead and profit                                  121,000
    Contingency                                                   271,000
Construction subtotal                                         $1,639,000

Post-closure costs
    Cap monitoring and maintenance                             $  108,000
    Fence maintenance                                               7,000
    Environmental monitoring                                      150,000
    Post-closure contingency                                        66,000
Post-closure costs subtotal0                                     $331,000
Totald                                                         $1,970,000
a. Costs are for 1995.
b. Includes net present value operating costs during remedial action.
c. Net present value assuming 5% interest (net of inflation) over 30 years.
d. Rounded to ten thousands.
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Table 12. BORAX-I selected remedy detailed cost estimated
Cost Elements
Estimated Cost
Construction
    Mobilize/demobilize cap subcontractor
    Construction of cap
    Surface soil consolidation*3
    Subsidence prevention
    Surface water control
    Air monitoring
    Miscellaneous
    Construction management
    Engineering design and inspection
    Contractor overhead and profit
    Contingency
Construction subtotal0
Post-closure costs
    Cap monitoring and maintenance
    Fence maintenance
    Environmental monitoring
    Post-closure contingency
Post-closure costs subtotal*1
Total*
  $   95,000
    274,000

      5,000
     20,000
     50,000
    162,000
    233,000
     79,000
    140,000
    182,000
 $1,240,000
 $   24,000
      3,000
    144,000
     43,000
  $214,000

 $1,450,000
a. Costs are for 1995.
b. Costs for soil consolidation are covered by the other cost elements.
c. Includes net present value operating costs during remedial action.
d. Net present value assuming 5% interest (net of inflation) over 30 years.
e. Rounded to ten thousands.
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                         10.  Statutory Determinations
    Remedy selection is based on CERCLA and the regulations contained in the National Oil and
Hazardous Substances Pollution Contingency Plan.  All remedies must meet the two threshold criteria
(see Section 8.1) established in the National Oil and Hazardous Substances Pollution Contingency
Plan: protection of human health and the environment, and compliance with ARARs. In addition,
CERCL/ requires that th? remedy uses permanent solutions and alternative treatment technologies to
the maximum extent practicable, and that the implemented action is cost-effective. Finally, the statute
includes a preference for remedies that employ  treatment that permanently and significantly reduce the
volume, toxicity, or mobility of hazardous wastes as their principal element. The following sections
discuss how the selected remedy addresses these statutory requirements.

               10.1  Protection of  Human Health and the Environment
    As described in Section 9, the selected remedy for both SL-1 and BORAX-I satisfies the criterion
of overall protection of human health and the environment by isolating contaminated materials from the
accessible environment. The remedy will maintain isolation for a sufficient period of time to allow
short-lived radionuclides to decay, thereby decreasing direct exposure risks.  Decay of short-lived
radionuclides (primarily cesium-137 and its progeny) will reduce direct exposure risks to  1 in 10,000 at
SL-1 after approximately 400 years and to 2 in  10,000 at BORAX-I after approximately 320 years.
The risk level at SL-1 will continue to decrease  to a lower limit of 3 in 1,000,000 after approximately
650 years, where it will remain due to the presence of long-lived uranium-235.  The risk level at
BORAX-I will decrease to 2 in 10,000 in about 320 years and will  stabilize due to long-lived
uranium-235.

    Although the National Oil and Hazardous Substances Pollution Contingency Plan established the
acceptability of risk to be within a range  of 1 in 10,000 to 1 in 1,000,000, the estimated long-term risk
levels cited above for SL-1 and BORAX-I are considered acceptable for several reasons.  First, the
Office of Solid Waste and  Emergency Response Directive 9255.0-30, dated April of 1991, states that
the upper boundary of this risk range is not a discrete line at 1 in 10,000 and that a specific risk esti-
mate around 1 in 10,000 may be considered acceptable if justified based on site-specific conditions.
On this basis, risk levels around 1 in 10,000 have been determined to be acceptable for remedial
actions implemented at other INEL operable units.  Second, there are no practical, safe, and cost-effec-
tive methods of removing the uranium-235  and its progenies from the contaminated  materials associat-
ed with the burial grounds. Any uranium-235 and its progenies removed would still require long-term
isolation  because there are no technologies  for accelerating radionuclide decay. Finally, the methodolo-
gy used in the baseline risk assessment to determine potential risks at SL-1 and BORAX-I resulted in
upper bound estimates; uncertainty analysis indicates that risk is likely over-estimated, not under-esti-
mated. Therefore it is probable that the long-term risJcs at BORAX-I, estimated at 2 in 10,000, may
actually be within the 1 in 10,000 to 1 in 1,000,000 range.
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    Several assumptions, as discussed in Section 6.1.4, were incorporated into the methodology of the
 baseline risk assessment to ensure an upper-bound estimate would be computed.  The assessment of
 residential scenarios was based on the assumption that direct contact with buried  waste would be main-
 tained for 24 hours a day, 350 days per year, for 30 years.  Similarly, occupational scenarios included
 the assumption that direct contact with buried waste would be maintained for 8 hours a day, 250 days
 per year, for 25 years.  For surface exposures, the assessments also included an assumption of homoge-
 neous contamination within soils, based on the highest radionuclide concentrations detected during
 sampling activities.  The result of these assumptions is most likely an over-estimation of the potential
 risks associated with the SL-1 and BORAX-I burial grounds.

    The remedy selected for both SL-1 and BORAX-I is containment by capping, with engineered  bar-
 riers comprised primarily of natural materials. The selected remedy will include consolidation of cont-
 aminated surface soils at BORAX-I for isolation beneath the engineered barrier. The engineered barri-
 ers will shield against penetrating radiation, discourage human and biotic intrusion, resist erosion,
 require low maintenance, and provide long-term performance and durability.  Until determined by the
 agencies to be no longer necessary, radiological surveys will be performed to ensure effective isolation
 of contamination at both sites. Monitoring of the engineered barriers will be performed until deter-
 mined by the agencies to be no longer necessary to ensure the integrity of the caps is not compromised
 by erosion or other deteriorating mechanisms. Additionally, institutional controls consisting of access
 restrictions (e.g., fencing, warning signs, and permanent markers) and runoff controls (e.g., contouring
 and grading as determined necessary) will be implemented to enhance isolation of the burial grounds.
 Land use will be restricted to  industrial applications for the duration of DOE operations at the INEL.
 The DOE  will request that the U.S. Department of Interior, Bureau of Land Management imposes simi-
 lar restrictions.

   Because this remedy will result in wastes remaining on site at both SL-1 and BORAX-I, reviews of
 this Record of Decision and monitoring data will be conducted. The initial review will be performed
 within five years of this Record of Decision signature with subsequent reviews conducted at least every
 five years thereafter until determined by the agencies to be no longer necessary. The purpose of these
 five-year reviews is to ensure  the remedy provides adequate protection of human health and the envi-
 ronment.

                            10.2 Compliance with ARARs
   The engineered caps for SL-1 and BORAX-I will be designed to meet all state and federal ARARs.
The ARARs that will be satisfied by the selected remedy are explained below.

 10.2.1 ARARs
   No chemical- or location-specific ARARs were identified for the remedial action at either SL-1 or
BORAX-I. A single action-specific ARAR was identified for the selected remedy at both SL-1 and
BORAX-I (see Section 7.1.2,  Table 8). The requirements of the rules for Control  of Fugitive Dust

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 (IDAPA 16.01.01.650 and .651) will be satisfied at both SL-1 and BORAX-I by application of appro-
 priate engineering controls to minimize generation of airborne contamination and dust during installa-
 tion of the engineered barriers and consolidation of surface soil at BORAX-I:

 10.2.2 To-Be-Considered Guidance
    In implementing the selected remedy, the agencies have agreed to consider a number of procedures
 and guidance documents that are not legally binding. The following list of DOE orders are to be con-
 sidered as guidance documents:

    •  DOE 5400.5, "Radiation Protection of the Public and Environment"
    •   DOE 5820.2A, "Radioactive Waste Management."
    These DOE orders provide guidance to ensure radiation protection for the environment and the
 public. DOE Order 5400.5 provides radiation protection standards to protect the general public from
 activities conducted at DOE sites.  DOE Order 5820.2A addresses future control of sites;  the DOE
 intends to maintain active institutional control of low-level radioactive waste disposal sites for 100
 years following closure.

                               10.3  Cost Effectiveness
    The selected remedy is cost-effective based on the overall protection to human health and the envi-
 ronment relative to the costs incurred. Due to the persistent toxicity associated with radionuclides,
 removing waste from SL-1 and BORAX-I simply results in the transfer of risk from one location to
 another with a significant increase in cost and short-term risk. Therefore, compared to other potential
 remedial actions, the selected remedy provides the best balance between cost and effectiveness in pro-
 tecting human health and the environment.

  10.4  Use of Permanent Solutions and Alternative Treatment Technologies to
                           the Maximum Extent Practicable
    The selected remedy utilizes permanent solutions to the maximum extent practicable for the SL-1
and BORAX-I burial grounds. The National Oil and Hazardous Substances Pollution Contingency
Plan prefers a permanent solution whenever possible. However, guidance established in the National
Oil and Hazardous Substances Pollution Contingency Plan to assist in the selection and implementation
of appropriate remedial actions states that EPA encourages the use of containment for waste that poses
a relatively low long-term threat or where treatment is impracticable. Therefore, the selected remedy
focuses on long-term containment, radiological monitoring, and institutional control of the burial
grounds, due to the persistent radiotoxicity associated with radionuclides. The selected remedy pro-
vides protection by isolating contaminated materials from the accessible environment for a sufficient
period of time to reduce potential exposure risks to acceptable levels. Based on analysis of the
CERCLA remedial alternative evaluation criteria and in particular the five balancing criteria (see
Section 8.2), containment provides the best remedy for  both the SL-1 and BORAX-I burial grounds in

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 terms of long- and short-term effectiveness, cost, implementability, and reduction of toxicity, mobility,
 and volume.  The following discussion highlights the tradeoffs among the alternatives considered for
 SL-1 and BORAX-I relative to the five balancing criteria.

    Long-term effectiveness is equally achieved by either containment or removal and disposal, because
 both remedial actions involve isolation from the accessible environment to ensure long-term protection
 of human health and the environment.  However, removal actions would involve significantly increased
 worker exposures during the short-term period of implementation. No action would not be effective in
 the short- or long-term.

    The toxicity of radionuclides associated with the burial grounds can only be reduced by natural
 decay; there are currently no technologies available to accelerate the decay process. Therefore, evalua-
 tion of the remedial actions considered with respect to reduction in toxicity is not applicable. In
 addition, the alternatives evaluated do not affect the volume of contaminated material existing at the
 burial grounds.  However, both the selected remedy and the removal and disposal alternative would
 result in significantly reduced mobility based on long-term isolation from the accessible environment.
 No action would not have an impact on toxicity, volume, or mobility of contaminants at SL-1 or
 BORAX-I.

    Lmplementability and cost are directly related to the  complexity of the remedial actions considered.
 Removal and disposal is the most complex alternative due to health and safety concerns associated with
 handling the contaminated materials buried at SL-1 and  BORAX-I. As a result, removal and disposal
 is the most difficult to implement and the most expensive alternative. Although no action would be
 unacceptable to the agencies, this alternative is technically easy to implement and the least expensive.
 The selected remedy is not complex and therefore is not difficult to implement and is much less expen-
 sive than removal and disposal.

    Relative to the five balancing criteria, short-term effectiveness, implementability, and cost were the
decisive factors  in selecting the containment alternative.  The containment alternative does not require
 intrusion into the burial grounds and therefore does not require worker exposure to the contaminated
 waste buried at SL-1 and BORAX-I. Furthermore, the containment alternative is not difficult to imple-
 ment and does not involve significant cost when compared to the removal and disposal alternative. No
 action was not considered a viable option.

    State and community acceptance were also included in the decision-making process for remedy
selection. The IDHW participated in the development and review of all required CERCLA documenta-
tion, including the remedial investigation/feasibility study, the proposed plan, and this Record of
Decision, and supports the selected alternative. The Environmental Management Site Specific
Advisory Board for the INEL concurred with the selection of the containment alternative at both burial
grounds and recommended that construction and monitoring costs be reduced to the extent possible to
reflect  the costs for similar actions performed within the private sector. In addition, public meetings
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 were held at various locations throughout the state, and publications were made available to inform,
 educate, and. encourage participation of the community regarding remedial activities associated with the
 SL-1 and BORAX-I burial grounds.

               10.5 Preference for Treatment as a Principal  Element
    Treatment was not considered in the formulation of potential alternatives for SL-1  and BORAX-I
 based on review of remedial actions previously selected for similar CERCLA sites. In addition, the
 nonhomogeneous characteristics associated with the wastes buried at SL-1 and BORAX-I rendered
 standard treatment techniques inappropriate. Contaminated materials buried at these sites include con-
 struction debris, with physical properties  ranging in size, shape, and material.  Furthermore, based on
 the inability of treatment to reduce the toxicity of radionuclides, the remedy selected did not consider
 treatment as a principal element.
               11.  Documentation of Significant Change
    Several refinements have been identified for the selected remedial action at the SL-1 and BORAX-I
burial grounds. These refinements are related to surface soil consolidation, monitoring, cost refine-
ments, the boundaries of Operable Unit 5-05, and other changes to the proposed plan and are described
in the following subsections.

                           11.1  Surface Soil Consolidation
    The information in the proposed plan indicated that the surface soils  around the burial grounds
could require consolidation due to the presence of wind-dispersed contamination.  Costs in the pro-
posed plan were developed as ranges to accommodate the potential for consolidation of surface soils
and the types of caps under consideration.  Refined cost estimates were prepared for this Record of
Decision based on no surface soil consolidation at SL-1, and consolidation of the entire 84,000-square
foot (7,800-square meter) area at BORAX-I.

    Subsequent to finalization of the proposed plan an evalua*'  - ^r new  data in conjunction with his-
torical sampling and survey data determined that surface soils surrounding the SL-1 burial ground do
not pose an unacceptable risk to human health or the environment. Soil ingestion, dust inhalation,
groundwater ingestion, and external exposure were evaluated for current  occupational and 30-year
future residential scenarios. Surface soil concentrations of identified  contaminants of concern outside
of the exclusion fence are at or below background values within Operable Unit 5-05.  Dose equivalent
rate measurements of the Operable Unit 5-05 surface soils indicate radiological field levels at or below
the average INEL level of 20 }irem/hr. The agencies have reviewed this information and concur that no
further action is appropriate for the surface soils outside of the exclusion fence within Operable
Unit 5-05. Documentation in  support of the decision can be found in the Administrative Record for
Operable Units 5-05 and 6-01  specifically in an engineering design file titled "ARA Windblown Area

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 Risk Evaluation" and an associated letter report titled "Assessment of Surface Soils Surrounding the
 SL-1 Burial Ground".

    It is expected that surface soil consolidation will be necessary at BORAX-I to appropriately man-
 age soil contamination and minimize the potential for human or environmental exposure to unaccept-
 able risks.  Therefore the refined cost estimate for capping the BORAX-I site incorporates the consoli-
 dation of surface soil option discussed in the proposed plan.

                                     11.2  Monitoring
    Long-term monitoring to confirm isolation of the buried contaminants for the accessible environ-
 ment and groundwater was described in the proposed plan. Environmental monitoring of air,  soil, and
 groundwater, and cap integrity monitoring to assess erosion, cracking, or other observable deterioration
 were included.  In the effort to refine costs the monitoring component was critically examined. It was
 determined that large components of the environmental monitoring could be incorporated into larger
 programs on the INEL at significant cost savings. Monitoring costs for the no action alternative were
 revised to be consistent with monitoring estimated for the selected Alternative 2.  Therefore the no
 action  alternative includes only soil monitoring. Alternative 3 did not include monitoring, and esti-
 mates have not changed.

 11.2.1  Groundwater Monitoring
    The results of the baseline risk assessment indicate risks via ingestion of groundwater of 1E-06 at
 the SL-1 burial ground and 3E-06 for the BORAX-I burial ground. These estimates, very low in the
 acceptable risk range, are upper bounds on risk because parameters for the groundwater  modeling were
 selected to maximize the potential risk estimates.  These estimates also represent the summation of
 risks due to all contaminants, regardless of modeled peak concentration time in the aquifer.

    Uncertainty analyses support the conclusion that there is no risk to groundwater from either burial
 ground; therefore, costs for groundwater monitoring have been eliminated. Installation of groundwater
 monitoring wells specific to these  sites, at an approximate cost of $200,000 per well, is not necessary.
 Therefore, groundwater monitoring needs will be determined under the Waste Area Group 5
 Comprehensive Remedial Investigation/Feasibility Study for WAG 5 and the Waste Area Group 10
 Comprehensive Remedial Investigation/Feasibility Study for WAG 6. This approach will be more cost
 eiiiw-ieiit because groundwater monitoring plans can be designed  to cover much larger areas. Five-year
reviews of monitoring data will be defined for the comprehensive remedial investigation/feasibility
 studies. In the unlikely event that  either burial ground is suspected of contributing to groundwater con-
tamination, additional site-specific monitoring wells or other means of contaminant migration  detection
can be  installed in the future.

11.2.2  Air  Monitoring
    Costs for long-term monitoring of air have been eliminated for both burial grounds for Alternatives
 1 and 2. An INEL-wide program is in place that would make additional  monitoring specific to either
site redundant. In compliance with the identified ARARs, site-specific air monitoring will be  per-

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 formed during the construction of the caps; after the remedial action is complete, responsibility for air
 monitoring at each site will be assumed by the site-wide program.

 11.2.3  Soil Monitoring

    Under Alternative 2, surface soils will be monitored by radiological surveys. For SL-1, cost esti-
 mates include radiological monitoring until the Waste Area Group 5 Comprehensive Remedial
 Investigation/Feasibility Study monitoring program is in place. At that time, long-term responsibility
 for these surveys will be placed under the Waste Area Group 5 program. Monitoring results and the
 need for continued monitoring will be evaluated during subsequent five-year reviews by the agencies.

    Because there will be no long term monitoring plan for Waste Area Group 6, estimates in this
 Record of Decision include costs for radiological monitoring of the BORAX-I site.  The need for con-
 tinued monitoring will be assessed periodically in the five-year reviews conducted by the agencies.

    Estimates for monitoring under the No Action Alternative 1 were revised to be consistent with the
 approach formulated  for Alternative 2.

                                 11.3 Cost Refinements

    The estimated costs for the selected remedy were presented in the proposed plan as ranges;
 $3,684,000 to $8,775,000 for SL-1, and $2,340,000 to $4,690,000 for BORAX-I. The refined cost esti-
 mates presented in this Record of Decision are $1,970,000 for SL-1 and $1,450,000 for BORAX-I.
 The cost refinements  result from the soil consolidation issues discussed in Section 11.1, monitoring
 discussed in Section 11.2, and refinements in general design parameters applied to the extent  possible
 without specific engineering designs. Further refinements of costs will be achieved when the remedial
 design is finalized and well-defined.

    Removing costs for goundwater and air monitoring (see Section 11.2) results in estimates for the
 No Action Alternative 1 of $188,000  for SL-1 and $180,000 for BORAX-I.


                          11.4 Operable Unit 5-05 Boundary

    In the proposed plan the boundary of OU 5-05 was defined as the 1,200- by 1,500-foot (366- by
477-m)  area around the SL-1 burial ground. The investigation of the surface soils and the external
exposure pathway discussed above in Section 11.1 was not limited to this region, but encompassed the
entire area defined by the isopleth illustrated in Figures 2 and 4.  Rather than assess a region in the
middle of one end of this isopleth, the agencies have agreed to expand the boundary of Operable
Unit 5-05 to include the northeast portion, about 40% of the entire area defined by the aerial isopleth.
This approach avoids the necessity for future reassessment and expenditure of additional funds for the
administration of the  additional evaluation.  Based on recently acquired dose equivalent rates, there are
no unacceptable external exposure risks due to surface soil outside the exclusion fence but  inside the
revised Operable Unit 5-05 boundary. There are no other pathways of concern for the surface soils in
the defined area.  Therefore no remedial actions will be necessary. Expanding Operable Unit 5-05 to
include  the surrounding surface soils  efficiently addresses the region and saves significant time and
funds. The remaining 60% of the area defined by the aerial isopleth will be addressed in the WAG 5
comprehensive RI/FS as site ARA-23.
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                      11.5 Other Changes to the Proposed Plan

    Several other minor changes have been made due to refinement of elements presented in the pro-
 posed plan.

    •  Institutional control: Institutional control will be maintained by DOE for at least 100 years to
       limit land use to industrial applications. Institutional controls will include placing written noti-
       fication of the remedial action in the facility land use master plan; the notification will prohibit
       any activities that would interfere with the remedial activity. A copy of the notification will be
       given to the Bureau of Land Management, together with a request that a similar notification be
       placed in the Bureau of Land Management property management records. The DOE will pro-
       vide EPA.and IDHW with written verification that notification, including Bureau of Land
       Management notification, have been fully implemented.

    •  Remedial action objectives:  The word "prevent" has been replaced with the word "inhibit" to
       more realistically describe each of the remedial action objectives.

    •  Biotic intrusion at BORAX-I: In the development of preliminary cap design, the agencies have
       reviewed the available data and concluded that a biotic barrier is not necessary for protection  of
       human health and the environment at BORAX-I.

    •  Biotic intrusion at SL-1:  In the  development of preliminary cap design, the agencies have
       reviewed the available data and concluded that a biotic barrier is not necessary over the entire
       SL-1 burial ground.  Layers to inhibit biotic intrusion will be placed  only directly over the dis-
       posal pits and trench.
              12.  Decision Summary for  No Action Sites
   This Record of Decision includes determinations for 10 Track  1 sites. The agencies have evaluated
each site and support decisions for no further action. Much of the  information discussed in previous
sections, particularly Sections 1 through 5, also applies to these 10 sites. Additional information specif-
ic to these sites is discussed in the remainder of this section, with individual descriptions of the 10 sites
in Section 12.6. Further details can be found in the Administrative Record for Waste Area Group 5.

                     12.1   Site Name, Location, and Description
   Waste Area Group 5 contains two groups of facilities:  the Auxiliary Reactor Area and the Power
Burst Facility (see Figure 9). The Auxiliary Reactor Area is comprised of four inactive facilities located
along Fillmore Boulevard north of Highway 20. The Power Burst Facility is just north of the Auxiliary
Reactor Area and consists of a total of five facilities spread radially around the Power Burst Facility
Control Area at the end of Jefferson Boulevard. Section 1 describes the topography, meteorology, sur-
face-water hydrology, geology, ecology, demography, and land use  for both areas.  The general descrip-
tion of groundwater hydrology is also the same, with site-specific depths to groundwater of approximate-
ly 667 feet (203 m) at the Auxiliary Reactor Area and 483 feet (147 m) at the Power Burst Facility.
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                      12.2  Site History and Enforcement Activities
    The Auxiliary Reactor Area was originally constructed in 1957 for U.S. Army research and devel-
opment of a compact power reactor. The area consisted of four facilities called Auxiliary Reactor
Areas I through IV.  In 1965 the Army program was discontinued.  Technical support services, not
including reactor operations, were continued until 1985, when the facilities were shut down. Three
Track 1 sites, two at Auxiliary Reactor Area I and one at Auxiliary Reactor Area IJJ, are included in
this Record of Decision.

    The Power Burst Facility was originally called the Special Power Excursion Reactor Test area.
Built in the late  1950s for reactor behavior and safety experiments, the facility  consisted of five areas,
the Control Area and Special Power Excursion Reactor Test Areas I through IV. After this series of
experiments terminated, all of the reactors were removed, and the individual facilities within the  area
were converted to other uses.  With the construction of a new reactor in 1970, the area was renamed the
Power Burst Facility. The Special Power Excursion Reactor Test Control Area became the Power Burst
Facility Control Area; Special Power Excursion Reactor Test Areas I through IV became, respectively,
the Power Burst Facility Reactor Area, the Waste Engineering Development Facility, the Waste
Experimental Reduction Facility, and the Radioactive Mixed Waste Storage Facility. Seven Track 1
sites located at the Power Burst  Facility are included in this Record of Decision.
PBF-24 Drainage Area

 PBF-19 Underground
         Tank Site
 PBF-14 Underground
         Tank Site
   PBF-13 Rubble Pit'
   PBF-28 Overspray.
     Area and Ditch
PBF-06 Drainage Area

    PBF-07 Oil Drum
       Storage Area
                                        Power Burst
                                        Facility Area
                                             r
                                                              Auxiliary Reactor Area
                                                                               ARA-1 3 Sanitary
                                                                               Sewer Tank and
                                                                               Leach Field
                                                                               ARA-17 Drainage Area
                                                                               ARA-05 Evaporation
                                                                               Pond
    1.  Power Burst Facility Reactor Area
    4.  Power Burst Facility Control Area
    7.  Auxiliary Reactor Area-Ill
2. Waste Engineering Development Facility
5. Radioactive Mixed Waste Storage Facility
8. Auxiliary Reactor Area-ll
                                                                      Not to scale
                                                                  3. Waste Experimental Reduction Facility
                                                                  6. Auxiliary Reactor Area-IV
                                                                  9. Auxiliary Reactor Area-l
Figure 9.  Waste Area Group 5 facilities and no further action sites.
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                     12.3 Highlights of Community Participation
    All 10 Track 1 sites were included in the proposed plan for the SL-1 and BORAX-I burial grounds.
Public comments were solicited at the same meetings and in the same comment periods discussed pre-
viously. No comments were received.

            12.4 Scope and Role of Operable Unit or Response Action
    Ten sites in Waste Area Group 5 are presented in this Record of Decision with no further action
determinations. As illustrated in Figure 9, three are located in the Auxiliary Reactor Area, and seven
are within the Power Burst Facility.  Of the twelve operable units in Waste Area Group 5, four have one
or more individual Track 1 sites presented here for no further action.

    All 10 sites were identified in the Federal Facility Agreement and Consent Order and evaluated
according to ENEL-specific guidance for Track 1 sites.  Qualitative Track 1 risk assessments evaluate
all available existing information and data, including site operating, waste, and disposal histories, engi-
neering drawings, and anecdotal evidence. These assessments examine only potential hazards to
human health, utilizing the assumption that actions taken to protect human health will also be protec-
tive of the environment. The information was  evaluated by representatives of the DOE, the IDHW, and
the EPA, who agreed that the sites did not warrant remediation or further study.

    As previously described, cumulative risks from each operable unit will be further evaluated in the
comprehensive remedial investigation/feasibility study for Waste Area Group 5.  Final evaluation of
site-wide impacts will be performed in the Waste Area Group 10 assessment.

12.4.1 Auxiliary Reactor Area Sites
    Operable Unit 5-01, located at the Auxiliary Reactor Area I, contains six sites; two of the six,
ARA-05 and ARA-17, are included in this Record of Decision. Also addressed is site ARA-13, the
only site in Operable Unit 5-11.  This Operable Unit is located at the ARA-III.

12.4.2 Power Burst Facility Sites
    All of the five sites in Operable Unit 5-03 (PBF-06, PBF-07, PBF-13, PBF-24) and PBF-28, are
included in this Record of Decision. Of these  five sites, four are located at the Power Burst Facility
Reactor Area and the fifth, PBF-24, is at the Radioactive Mixed Waste Storage Facility.  The other two
Power Burst Facility sites are two of the three  sites in Operable Unit 5-04, site codes PBF-14 and
PBF-19. PBF-14 is located at the Waste Engineering Development Facility. PBF-19 is adjacent to the
Waste Experimental Reduction Facility.
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                                 12.5  Site Characteristics
    The complete Track 1 Decision Documentation Packages and other information supporting the
evaluations for these sites can be found in the Administrative Record. Standard exposure pathways and
scenarios were evaluated according to the INEL-specific guidance for assessing Track 1 sites.  Potential
exposure routes considered were external exposure to ionizing radiation, soil ingestion, inhalation of
dust, inhalation of volatiles, and groundwater ingestion.  Both current occupational and future  residen-
tial scenarios were qualitatively evaluated.  The following section summarizes the contaminants consid-
ered for each site and the results of the qualitative risk assessments.

                               12.6  Summary of Site Risks
    The 10 sites were categorized for discussion and summary into three different types:  wastewater
disposal  sites, soil contamination sites, and underground storage tanks.

12.6.1 Wastewater Disposal Sites
    The six sites discussed in the following subsections were associated with liquid waste discharges.
During the initial  site identifications, several of these sites were only suspected of receiving hazardous
or radioactive wastes. Subsequent evaluation determined that no disposal activities had occurred.
Other sites were identified as recipients of contaminated wastes, but evaluation determined that dis-
charges were neutralized, biodegraded, or in quantities too small to pose an unacceptable risk.

    12.6.1.1  ARA-05. ARA-05 in Operable Unit 5-01 was originally described in the initial site iden-
tification as an evaporation pond northeast of ARA-I. The area is a shallow natural depression in the
ground that may have received some runoff from an adjacent small parking lot.  There are no records
of waste  generation or disposal processes associated with this site, nor are there any records indicating
that the site was ever the intended destination of any waste stream. Historical monitoring surveys
detected the presence of random radioactive particles in both the pond area and the general vicinity
around ARAs I and II. These hot particles were probably a result of the SL-1 accident and cleanup
efforts. This site was prepared in 1993 for removal of radioactive particles, but the survey indicated
that the area was free of radioactivity above the ambient background.

    12.6.1.2  ARA-17. ARA-17 in Operable Unit 5-01 is a nearly flat drainage area south of ARA-I
that received drainage from two sources:  the boiler room blow-down from the Hot Cells  building and
the raw-water storage tank and pump house at the southwestern corner of the facility.  Surface  dimen-
sions are  approximately 150 by 150 feet (46 by 46 m). There are no known concentrations of radiolog-
ical contamination above background levels at this site, as confirmed by radiological surveys, and no
evidence  of nonradiological constituents. Historical documents and process information pertinent to
ARA-I do not indicate that this site was the intended destination of any waste stream except uncontam-
inated water.
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    12.6.1.3  PBF-28.  PBF-28 in Operable Unit 5-03 consists of an overspray area of surface soils
 north of the drainage ditch that is south and west of the Power Burst Facility Reactor Area cooling
 tower. The reactor cooling tower began service in 1976 and received reactor secondary cooling water
 until 1985. The drainage ditch was constructed in the early 1970s and is approximately 600 feet (183
 m) in length. This drainage ditch was used for surface runoff drainage from the reactor area.  It also
 received water from  the boiler blow-down tank and discharge or overflow of secondary cooling water
 from the cooling towers. Soil samples were collected along the entire length of the drainage ditch and
 the cooling tower area  and analyzed for chromium, the primary contaminant of concern.  Results indi-
 cated a 100- by  100-foot (30- by 30-m) area was contaminated by aerosol overspray from the cooling
 tower. However, the concentrations of chromium found at this site are substantially below risk-based
 contaminant levels and surveys indicate no radiological activity above background levels for the cool-
 ing tower area or the drainage ditch.

    12.6.1.4 PBF-06.  PBF-06 in Operable Unit 5-03 is a ditch located west of the Power Burst
 Facility reactor building. A pipe running from the oil-fired boiler has emptied approximately 30 gal-
 lons (114-liters) per day of blow-down water into the pit since 1970.  Although the reactor was placed
 in a standby status in 1985, the boiler is still being used to support ongoing activities at the facility,
 which require continued release of the boiler blow-down water. The blow-down water contains some
 chemicals that are used to  inhibit corrosion in the boiler.  However, the corrosion inhibitors used con-
 tain no hazardous chemicals, are nontoxic, and are used in very small quantities.  A radiological survey
 conducted in 1991  found no radiological contamination above background levels at this site.

    12.6.1.5 PBF-24. PBF-24 in Operable Unit 5-03 is a boiler blow-down pit that was used  for
 drainage of the reactor building boiler waters from 1960 to  1971.  The 2- by 2- by 6-foot (0.6- by 0.6- by
 1.8-m) pit, located 30 feet (9 m) north of the reactor building, is a subsurface reinforced concrete struc-
 ture and has an open gravel base for drainage.  A pipe running from the oil-fired boiler emptied approxi-
 mately 30 gallons (114 liters) per day of blow-down water into the pit. The blow-down water contained
 some chemicals that were used to inhibit corrosion in the boiler.  However, the corrosion inhibitors used
 contained no hazardous  chemicals, were relatively nontoxic, and were used in very small quantities.
 Radiological surveys show no radiological contamination above background levels at this site.

    12.6.1.6 ARA-13.  ARA-13 in Operable Unit 5-11 consists of a septic tank, a distribution box, and
 a drain field at Auxiliary Reactor Area ID. Sanitary wastes were disposed into the system from 1969 to
 1980. Between 1980 and 1983, in addition to sanitary wastes, small quantities of hazardous laboratory
wastes were diverted  to this system. Sampling and analysis yielded low-level concentrations  of arsenic,
barium, beryllium, mercury, nickel, selenium, and thallium in four samples taken from the leach field.
The metals were detected at depths from 1 to 6 feet (0.3 to 1.8 m). However, concentrations were lower
than background metal  concentrations found in soils at other operable units at the INEL. The contents
of the system were  sampled and analysis showed concentrations were below levels that would present an
unacceptable risk.
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 12.6.2  Soil-Contamination Sites
    The following two Track 1 sites were classified as potential soil-contamination sites. One site was
 suspected of having received hazardous waste and possible oil spillage, but subsequent site evaluation
 determined that no such disposal activities had occurred.  The other site was a dump for a variety of
 materials, including piping with asbestos insulation and some heavy metals. The asbestos has been
 removed, and subsequent evaluation of the site indicated that remaining contaminant concentrations do
 not pose an unacceptable risk to human health or the environment.

    12.6.2.1 PBF-07. PBF-07 in Operable Unit 5-03 is the location of an oil drum storage area at the
 Power Burst Facility Reactor Area. The site consists of a wholly enclosed 4- by 8-foot (1.2- by 2.4-m)
 concrete pad, which is used to temporarily store two or three 55-gallon (208-liter) drums of used oil
 and lubricant until pick up for recycling. The site initially only had a  steel roof covering the oil drums,
 but in 1990, the pad was enclosed with metal corrugated siding, and a drip pan was installed. There
 have been no recorded oil spills and the site shows no physical evidence of spillage. No hazardous
 substances have been stored on the site, and a radiological survey conducted in 1991 detected no radio-
 logical activity  above background.

    12.6.2.2  PBF-13. PBF-13 in Operable Unit 5-03 is a rubble pit located north of the Power Burst
 Facility Reactor Area cooling  tower. The rubble pit was first used to dispose of soil and basalt pieces
 excavated during facility construction in the late 1960s and was later used as a dump for a variety of
 construction materials until approximately the mid-1970s. Fence posts mark the location of the 75- by
 45- by 10-foot (23- by 14- by  3-m) dumping area.  The dump received lumber, rusting empty barrels
 and cans, cable, concrete, and piping with asbestos insulation. All visible materials containing asbestos
 were removed from the pit in  1993. Any small quantity that remains was covered when the pit was
 backfilled with  3 to 12 feet (0.9 to 3.7 m) of clean soil and basalt rubble. Soil samples indicated the
 presence of cadmium, chromium, lead, nickel, and zinc in small amounts consistent with background
 levels.  Volatile  organic compounds detected at very low concentrations were acetone and toluene.

 12.6.3 Underground Storage Tanks
   The following two Track 1 sites were associated with underground storage tanks.  One of the tanks,
its contents, associated piping, and contaminated soil have been removed.  This site is now paved and
 used for storage. The other tank was filled with sand, disconnected from the associated piping, and
 abandoned in place. Risk evaluations determined that possible residual soil contamination would not
pose an unacceptable risk.

   12.6.3.1  PBF-14. PBF-14 in Operable Unit 5-04 is the site of a buried 500-gallon (1,893-liter)
gasoline tank once used to power an emergency generator. The tank was in service from 1960 to 1964,
when the Special Power Excursion Reactor Test II reactor was functional. The tank was filled with
sand and abandoned in place with the fuel line disconnected. Two posts prevent parking on the tank
site.  The top of the tank is about  2 feet (0.6 m) below the surface. During the Track 1 investigation,

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soils were excavated down to the top of the tank to a depth of 2 to 2.5 feet (0.6 to 0.8 m). No stained
soils were visible, volatile organic compounds were not detected and there were no holes observed in
either the tank or associated piping.

    12.6.3.2 PBF-19.  PBF-19 in Operable Unit 5-04 was a 3,000-gallon (11,355-liter) underground
fuel oil storage tank associated with the furnace in the reactor building at the Special Power Excursion
Test Reactor ffl.  Documentation from 1986 indicates that the tank and any contaminated soil associat-
ed with the tank  were scheduled for removal, but post-removal records were not found. Although evi-
dence that the tank was removed versus abandoned in place is not confirmed, it is likely that the tank
and any associated contaminated soil were removed in 1986.  The area has since been paved and is
now used for outside storage.

                    12.7  Description of the No Action Alternative
   Based on  the information summarized above from the supporting documents placed in the
Administrative Record, the 10 Track 1 sites described do not pose an unacceptable risk to either human
health or the environment. No further action is warranted.  Although no additional efforts will be
expended to remediate or assess these sites individually, each will be considered again  for cumulative
effects in the comprehensive remedial investigation/feasibility study for Waste Area Group 5 and the
site-wide assessment for Waste Area Group 10.
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      Appendix A
Responsiveness Summary
          A-1

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CM

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                                     Appendix A

                          Responsiveness Summary



                                   A.1  Overview
    Operable Unit 5-05 is within Waste Area Group 5 of the Power Burst Facility/Auxiliary Reactor
 Area at the ENEL. The unit comprises the SL-1 burial ground and surrounding area.  Operable Unit
 6-01 is within Waste Area Group 6 of the  Experimental  Breeder Reactor-I/Boiling Water Reactor
 Experiment at the INEL and comprises the BORAX-I burial ground and surrounding area.  Both of
 these operable units are described in the Record of Decision to which this Responsiveness Summary is
 attached. Due to the similarities of the two operable units, they were investigated together. A proposed
 plan was released April 28,  1995, with a public comment period from May 3 to June  3, 1995. The pre-
 ferred alternative recommended in the proposed plan is containment by capping with an engineered
 long-term barrier comprised primarily of natural materials. This Responsiveness Summary recaps and
 responds to the comments received during the comment period.  Generally, the comments reflect a
 broad range of views, from strong support for the selected alternative to opposition and support for
 Alternative 3, Removal and Disposal.

                   A.2  Background on Community Involvement

   In accordance with CERCLA §113(k)(2)(B)(i-v) and 117, a series of opportunities for public infor-
 mation and participation in the remedial investigation and decision process for the SL-1 and BORAX-I
 burial grounds were provided to the public from September 1994 througn May 1995.  For the public,
 the activities included receiving fact sheets that briefly discussed the investigation to date, INEL
Reporter articles and updates, a proposed plan, an availability session and public meetings. A few
members of the public received telephone  briefings

   In September 1994, a kickoff fact sheet concerning the SL-1  and BORAX-I remedial
 investigation/feasibility study was sent to about 6,700 individuals of the general public and to 650
 INEL employees on the INEL Community Relations Plan mailing list.  The fact sheet contained a
postage-paid comment form to solicit early public input  on the investigations.

   The investigations were discussed at informal semiannual briefings in Twin Falls (October 11,
 1994), Pocatello (October 13, 1994), Moscow (October  18, 1994), Boise (October 19, 1994), and Idaho
Falls (October 20, 1994). During these briefings, representatives from the DOE and INEL discussed
the projects with members of the community, answered questions, and listened to public comments.
                                           A-3

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    Regular reports concerning the status of the project were included in the INEL Reporter and mailed
 to those who were on the mailing list. Reports also appeared in two Citizens' Guides.

    In April 1995, a fact sheet concerning the project was sent to about 6,700 individuals of the general
 public and 650 ENEL employees on the INEL Community Relations Plan mailing list.  On April 11,
 1995, the DOE issued a news release to more than 100 news media contacts concerning the beginning
 of a 30-day public comment period, which began May 3, 1995 and ended June 3, 1995, pertaining to
 the proposed plan for SL-1 and BORAX-I. Many of the news releases resulted in a short note in com-
 munity calendar sections of newspapers and as public service announcements on radio  stations. Both
 the fact sheet and news release gave notice to the public that documents for SL-1 and BORAX-I would
 be available before the beginning of the comment period in the Administrative Record section of the
 INEL Information Repositories located in the INEL Technical Library of Idaho Falls, the INEL Boise
 Office, as well as  in public libraries in Idaho Falls, Fort Hall, Pocatello, Twin Falls, Boise, and the
 University of Idaho Library in Moscow.  Also, table top displays were set up at the Grand Teton Mall
 in Idaho Falls (May 15-20), Burley Public Library (April 24-May 5), Twin Falls Public Library (May
 5-26), Boise Towne Square Mall (April 29), and  the Pocatello City Building (April 24-May 15).

    Opportunities  for public involvement in the decision process for SL-1 and BORAX-I were provided
 beginning in May 1995. For the  public, the activities ranged from receiving the proposed plan, con-
 ducting one teleconference call, and attending open houses and public  meetings to informally dis-
 cussing the issues and offering verbal and written comments to the agencies during the  30-day public
 comment period.

    Copies of the proposed plan for the burial grounds were mailed to about 6,700 members of the pub-
 lic and 650 INEL employees on the INEL Community Relations Plan mailing list on April 28,  1995,
 urging citizens to comment on the proposed plan and to attend public meetings. Display advertise-
 ments announcing the same information and the location of public meetings on May  16, 17, and 18,
 1995, in Idaho Falls, Boise, and Moscow, respectively, appeared in seven major Idaho newspapers. All
 of the public meetings were held on the scheduled days. Large advertisements  appeared in the follow-
 ing Idaho newspapers on April 26:  Post Register (Idaho Falls); Idaho State Journal (Pocatello); South
 Idaho Press (Burley); Times News (Twin Falls); Idaho Statesman (Boise); Lewiston Morning Tribune
 (Lewiston); and The Daily News  (Moscow).

   Personal calls were made to stakeholders in Idaho Falls, Pocatello, Twin Falls, Boise, and Moscow
 the week of May 8 and  15 to remind individuals about the meetings. A post card was mailed on May
 10,  1995, to about 6,700 members of the public and 650 INEL employees on the INEL  Community
Relations Plan mailing list to encourage them to attend the public meetings and provide verbal or writ-
ten comments. Both media, the news release and newspaper advertisements, gave public notice of pub-
 lic involvement activities and offerings for briefings, and the beginning of a 30-day public comment
period that was to  begin May 3 and run through June 3, 1995.
                                            A-4

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    Written comment forms, including a postage-paid business-reply form, were made available to
 those attending the public meetings. The forms were used to turn in written comments at the meeting,
 and by some, to mail in comments later. The reverse side of the meeting agenda contained a form for
 the public to evaluate the effectiveness of the meetings. A court reporter was present at each meeting
 to record transcripts of discussions and public comments.  Transcripts from the three public meetings
 were placed in the Administrative Record section for the SL-1 and BORAX-I burial grounds, Operable
 Units 5-05 and 6-01, in five INEL Information Repositories. A total of about 10 people attended the
 public meetings. Overall, eight provided formal comment; of these eight people, three provided oral
 comments and five provided written comments. For those who did not attend the public meetings but
 wanted to make formal written comments, a postage-paid comment form was attached to the proposed
 plan. All comments received on the proposed plan were considered during the development of this
 Record of Decision.

    This Responsiveness Summary has been prepared as part of the Record of Decision. All formal
 verbal comments, as given at the public meetings, and all written comments, as submitted, are included
 in the Administrative Record for the Record of Decision. Those comments are annotated to indicate
 which response in the Responsiveness Summary addresses each comment. The Record of Decision
 presents the preferred alternative for the project, selected in accordance with CERCLA, as amended by
 the Superfund Amendments and Reauthorization Act and, to the extent practicable, the National Oil
 and Hazardous Substances Pollution Contingency Plan.  The decision for this operable unit is based on
 information contained in the Administrative Record.

                    A.3 Summary of Comments with Responses

   Comments and questions raised during the public comment period on the SL-1 and BORAX-I bur-
 ial grounds proposed plan are summarized below.  The public meetings were divided into an informal
 question-and-answer session and a formal public comment session. The meeting format was described
 in published announcements and meeting attendees were reminded of the format at the beginning of
 each meeting. The  informal question-and-answer session was designed to provide immediate responses
 to the public's questions and concerns.. Several questions were answered during the informal question-
 and-answer period during the public meetings on the proposed plan.  This Responsiveness Summary
 does not attempt to  summarize or respond to issues and concerns  raised during that part of the public
 meeting.  However, the Administrative Record contains complete transcripts of these meetings, which
 include the agencies' responses to these informal questions.

   Comments received during the formal comment session of the meeting were addressed by the agen-
cies in this Responsiveness Summary. The  public was requested to provide their comments in writing,
 verbally during the public meetings,  or by recording  a message by calling the INEL's toll-free number.
 Seven written comments were received and 12 verbal comments were offered during the public meet-
ings. This Responsiveness Summary responds to those comments.

                                            A-5

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 1.  Comment: One commenter asked what the maximum doses are regardless of time, at least to
    10,000 years, and how these compare to the maximum dose limits of Nuclear Regulatory
    Commission and the DOE for an unrecognized abandoned radiation waste disposal facility.

    Response:  The annual dose was estimated for the SL-1 and BORAX-I burial grounds based on the
    residential intrusion scenario beginning 30 years in the future. This scenario was selected because
    it represents the "maximum dose" at the time of earliest possible public access to either site.
    Selection of this exposure scenario from the 10 scenarios modeled in the baseline risk assessment
    represents the highest risk to the public and is also consistent with the proposed plan.

    Risk spreadsheets generated for the baseline risk assessment provided the starting point for the esti-
    mation of dose.  Radionuclides posing a risk less than 1 in 10,000,000 for a given pathway were
    screened from this evaluation as insignificant contributors to the total dose.  The methodology,
    including formulae, source terms, and dose conversion factors used to estimate annual dose rates, is
    presented in the technical memorandum titled Dose Conversions for the SL-1 and BORAX-I Burial
    Grounds,  and can be found in the Administrative Record for Operable Units 5 and 6.

    Results of the calculations for the 30-year residential intrusion scenarios are summarized below. A
    limit of 25 mrem/yr for members of the public has been established by the Nuclear Regulatory
    Commission and by the DOE.

Table A-1. Estimates of dose for the 30-year residential intrusion scenario.
                                                     Estimated Annual Dose Rate
Site           Pathway                                       (mrem/yr)
SL-1           External exposure                                  34,000
               Soil ingestion                                          69
               Dust inhalation                                          0.31
               Groundwater ingestion                                   0.043
               Total (2 significant digits)                          34,000
BORAX-I      External exposure                                   1,800
               Soil ingestion                                           7.0
               Dust inhalation                                          0.14
               Groundwater ingestion                                   0.64
               Total (2 significant digits)                           1,800

2.   Comment:  Two commenters feel that models used for groundwater fate and transport must be
    benchmarked and validated before we can proceed with action or no action.

    Response: GWSCREEN was the groundwater modeling code used to estimate groundwater concen-
    trations and potential risks due to groundwater ingestion. This code was designed to EPA and IDHW
    specifications to address conditions and uncertainties pertinent to the INEL. Worst case upper bounds

                                            A-6

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    of concentrations and risks were generated by using EPA and IDHW approved default input parame-
    ters defined for evaluating Track 2 sites (sites about which little is known, and low risk is expected).
    The code has been validated by benchmarking against the PORFLOW and GRDFLX codes, both of
    which are well known and accepted codes in groundwater modeling.  GWSCREEN results were
    within 5% of both PORFLOW and GRDFLX results. Further information regarding the develop-
    ment, validation, and benchmarking of GWSCREEN can be found in the following documents which
    are available in the Administrative Record for Operable Units 5-05 and 6-01.

    Rood, A. S. and R. C. Arnett, J. T. Barraclough.  Contaminant Transport in the Snake River Plain
    Aquifer: Phase I, Part 1: Simple Analytical Model of Individual Plumes" EGG-ER-8623, May 1989.

    Matthews, S.  D., "Software Configuration Management Plan for Controlled Code Support System",
    EGG-CATT-10196, April 1992.

    Rood, A. S., "Software Verification and Validation Plan  for the GWSCREEN Code",
    EGG-GEO-10798, May  1993.

    Smith, C. S, and C. A. Whitaker, "Independent Verification and Limited Benchmark Testing of the
    GWSCREEN Computer Code, Version 2.0", GEE-GEO-10799, June 1993.

    Rood, A. S., "GWSCREEN: A Semi-Analytical Model  for Assessment of the Groundwater Pathway
    from Surface or Buried Contamination Theory and User's Manual Version 2.0", EGG-GEO-10797,
    June 1994, Revision 2.

    Rood, A. S, "GWSCREEN: A Semi-Analytical Model for Assessment of the Groundwater Pathway
    from Surface or Buried Contamination: Theory and User's Manual", EGG-GEO-10158, March 1992.

    DOE, Track 2 Sites: Guidance for Assessing Low Probability Hazard Sites at the INEL, DOE/ID-
    10389, January 1994, Revision 6.

3.   Comment: One commenter requested information regarding the water transport time from the sur-
    face to the aquifer, and flow rate in the aquifer used in  the groundwater modeling. The commenter
    also inquired about the extremes examined in the uncertu^..^ ^...alysis, what kind of uncertainty
    analyses were done, and the resultant extremes of dosage imposed by the more significant radionu-
    clides in the aquifer plumes from SL-1 and BORAX-I.

 .   Response: Vadose zone water travel times used in the evaluation were 18 years for SL-1 and
    66.3 years for BORAX-I. The GWSCREEN model (see comment #2) uses water travel times esti-
    mated using only sediment thicknesses in the vadose zone. Water travel time through the basalts was
    neglected because describing water movement through the basalts in the vadose zone is not scientifi-
    cally well-defined. Neglecting the travel time through basalt results in conservative estimates. The
    average  linear water velocity in the aquifer was specified as 570 m/yr for both facilities.
                                            A-7

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    A parametric sensitivity/uncertainty analysis was performed for both SL-1 and BORAX-I for those
    parameters that were thought to most significantly affect the results.  Sensitivity calculations were
    done only for the radionuclides with the highest estimated groundwater risk at each facility bound-
    ary using base case parameters. The radionuclides were technetium-99 for SL-1 and U-234 for
    BORAX-I.  Parameters varied in the analysis were: infiltration rate, vadose zone sediment thick-
    ness, sediment moisture content, distribution coefficient, aquifer porosity, aquifer dispersivity, and
    well-screen thickness.  Each parameter was varied over a range and only one parameter was varied
    at a time, except infiltration rate and moisture content which were related through the moisture
    characteristic curve for the sediment.

    Vadose zone water travel times for base case calculations as well as minimum and maximum values
    investigated as part of the sensitivity/uncertainty analysis are shown in Table A-2. The minimum
    and maximum vadose zone water travel times were a result of varying the vadose zone thickness or
    infiltration rate.

Table A-2. Minimum and maximum vadose zone water travel times (years) considered in the sensitiv-
ity/uncertainty analysis.
Facility/Location
SL-1
BORAX-I
Base Case Value
18
66.3
Minimum Value
10.2a
42.5a
Maximum Value
54.4b
156C
a. Using minimum value of vadose zone sediment thickness and base case infiltration.
b. Using maximum value of vadose zone sediment thickness and base case infiltration.
c. Using minimum value of infiltration rate and base case vadose zone sediment thickness.

   The average linear groundwater velocity was not varied as part of the sensitivity/uncertainty analy-
   sis because the burial ground boundary receptor is so close to the source that the concentration and
   corresponding risk values are relatively insensitive to changes in this parameter.  The term average
   linear groundwater velocity is the average speed traveled by water in the aquifer, and is often
   referred to as aquifer pore velocity.

   TLe results of the sensitivity/uncertainty  analysis were presented as a percent change from the base
   case peak groundwater concentration.  This comparison can be extended to risk because the rela-
   tionship between concentration and risk is linear.  For SL-1, the changes in concentration ranged
   from a minimum of 19% (of base case concentration)  using the maximum well screen thickness
   (vertical mixing  zone) to a maximum of  301% (of base case concentration) using the minimum
   aquifer dispersivities.  For BORAX-I, the changes ranged from a minimum of 8% to a maximum of
   970%. Both of these are the result of using the minimum and maximum distribution coefficients.
   A more complete discussion of the sensitivity/uncertainty analysis as well as a discussion of the
   effect of each parameter and assumption can be found in Appendix C, Section C-5, of the remedial
   investigation/feasibility study report.

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    Because annual dose due to groundwater ingestion is insignificant (see Comment #1), sensitivity
    analyses to generate the extremes of dose by radionuclide, as requested by this commenter, were
    not generated.

4.  Comment: One commenter requested more information regarding potential contaminant plumes and
    stated that cumulative impacts from various facilities must be considered to at least 10,000 years in
    the future, not contributions from individual sites for only  100 or 1,000 years. Specific questions
    included "Will the SL-1 contaminant plume in the aquifer overlap the plume from BORAX-I?", and
    "Will these plumes overlap the plume from the previously evaluated RWMC Pad A?"

    Response: It is unlikely that potential groundwater plumes from SL-1 and BORAX-I will overlap
    and cause significant concentrations.  Figure 1 in the Record of Decision shows the locations of the
    INEL site boundary receptors for SL-1 and BORAX-I.  These locations were determined based on
    the regional groundwater flow direction which is to the southwest. Radionuclide concentrations
    from both SL-1 and BORAX-I were predicted to decrease several orders of magnitude by the time
    they reached the INEL site boundary receptors. It is doubtful that the plumes would overlap on the
    INEL unless  there were an uncharacteristically large degree of spreading. Any plume overlap
    would likely  occur off the INEL site.  At that point, the additive concentrations of any plume over-
    lap would be much less than those predicted at the burial ground boundary, facility boundary, and
    probably the  INEL site boundary.  Nevertheless, overlap of plumes will be considered in the
    sitewide groundwater assessment in conjunction with the Waste Area Group 10 remedial investiga-
    tion/feasibility study.

    The possibility of potential groundwater plumes from other facilities was not evaluated It is likely
    however, that a plume from BORAX-I would overlap a plume from Pad A given the relatively close
    proximity of the two sites. Any impact of overlaps will be evaluated in Waste Area Group 10.

    The peak  radionuclide groundwater concentrations were calculated irrespective of any time frame.
    Several  radionuclides were predicted to take more than  10,000 years to reach the aquifer. For con-
    servatism, the peak groundwater concentrations of each radionuclide were assumed to occur at the
    same time for each receptor.

5.   Comment: One commenter wanted to know how the requirements of 40 CFR 193, particularly
    10,000 year disposal requirements, and the Low-Level Waste Policy Act of 1985 are  being met for
    these two sites, described by the commenter as "inactive disposal sites for spent fuel, transuranic
    waste, greater than Class C waste, and low-level waste."

    Response: The preproposal draft of 40 CFR 193 states explicitly that "The management and stor-
    age standards are  not intended to apply to remedial actions at LLW facilities  which were closed
    prior to  the effective date of 40 CFR part 193...". The draft acknowledges that it may be years
    before 40 CFR  193 is finalized.  40 CFR 193 does not qualify as an ARAR until it becomes law.
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 Capping of the two burial grounds does, however, satisfy the intent of the preproposal draft. The
 draft states that "The only practical method of reducing the radiation hazard from LLW is to isolate
 it from people and the environment until the radioactivity has decayed," and the proposed standards
 should consider "...the protection provided by the engineered and natural barriers of a disposal sys-
 tem."  The caps will be designed to prevent human or environmental exposure to the wastes for 400
 years at SL-1 (when the external exposure risk will reach 1E-04) and 320 years at BORAX-I (when
 the long-lived uranium-235 becomes the primary risk contributor at 2E-04).

 In terms of possible intrusion into the waste, the draft states that "the standards have not been
 devised to protect individuals who purposefully or inadvertently farm on the superjacent land or
 penetrate into the waste.  They do apply outside the area delineated by permanent markers and in
 records of government ownership." It is anticipated that these restrictions will be specified in the
 remedial design phase which follows the signing of this Record of Decision.

 The EPA proposes  a standard of 15 mrem committed effective dose per year (equivalent to a fatal
 cancer risk of 5E-04) to the public, outside of the area delineated by permanent markers and
 recorded government ownership.  Shielding provided by the caps will be adequate to keep expo-
 sures below 15 mrem/yr above background.

 The commenter referred to disposal requirements for  spent fuel, transuranic waste, and greater-
 than-Class C waste. The wastes buried at both SL-1 and BORAX-I do not meet the definition of
 these waste types.  All wastes associated with the SL-1 and BORAX-I burial grounds are consid-
 ered low-level waste. The following paragraphs clarify this point.

 Spent nuclear fuel is defined in DOE Order 5820.2A (Radioactive Waste Management), Attachment
 2, as "Fuel that has been withdrawn from a nuclear reactor following irradiation, but that has not
 been reprocessed to remove its  constituent elements." Neither the SL-1 or BORAX-I reactor oper-
 ated for long enough to achieve burn-up to the design core lifetime prior to destruction of the facili-
 ties. Thus, the fuel never became "spent".

 Transuranic waste is defined in DOE Order 5820.2A,  Attachment 2, as "Without regard to  source or
 form, waste that is contaminated with alpha emitting transuranium radionuclides with half-lives
 greater than 20 years and concentrations greater than  100 nCi/g  at the time of assay."  The  concen-
trations of transuranium radionuclides at SL-1 are estimated to be in the pCi/g range and no
transuranium radionuclides were identified as contaminants of concern at BORAX-I.  Thus, no
transuranic wastes exist at either burial ground.

A comparison of the radionuclide concentrations associated with the SL-1 and BORAX-I burial
grounds with Class C waste determination criteria revealed that no  waste containing concentrations
in excess of Class C levels exists at either site. This determination  is based on the assumption of
uniform distribution of contaminants throughout the estimated volume.  Therefore, it is possible
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    that localized areas of higher concentrations could exceed Class C criteria.  However, based on the
    comparison performed, contaminant concentrations are below the lower end of the Class B criteria
    range.

    All the waste associated with both burial grounds does meet the definition of low-level waste, as
    defined in DOE Order 5820.2A, Attachment 2:

       "Waste that contains radioactivity and is not classified as high-level waste, transuranic waste,
       or spent nuclear fuel or 1 l(e) byproduct material as defined by this Order. Test specimens of
       fissionable material irradiated for research and development only, and not for the production of
       power or plutonium, may be classified as low-level waste, provided the concentration of
       transuranic is less that 100 nCi/g."

    Therefore, only low-level radioactive waste management and disposal requirements are considered
    relevant to the SL-1 and BORAX-I burial grounds.

    The commenter also referenced disposal requirements specified in the Low-Level Waste Policy Act of
    1985.  The act specifically excludes low-level waste owned or generated by the DOE. DOE
    Order 5820.2A specifies requirements for managing and disposing DOE owned and generated low-
    level waste.  This DOE Order specifies that inactive sites such as SL-1 and BORAX-I be managed in
    conformance with CERCLA, which is the process currently being undertaken. The Order does not
    specify retrofitting such inactive sites to meet the requirements that would apply for new or operating
    disposal facilities.

6.   Comment:  One commenter calls the reports "excellent and interesting" but thinks cost estimates
    are too high, especially for construction management and contractor u v erhead and profit. The com-
    menter states that competitive bidding on a  fixed price design that is simple and clear should reduce
    estimated costs by 25 to 50%.

    Response:  Cost estimates for the alternatives analyzed were developed for comparison purposes
    only, and will not likely reflect the actual cost of implementing the selected alternative.  The cost
    estimates were developed on the basis of a preliminary conceptual design, and therefore have omit-
    ted many specific details of the  alternatives  that were not well defined. These specific details are
    accounted for within a contingency cost element included in each estimate.  However, the com-
    menter judged the estimates as being excessive by 25 to 50 percent.  This evaluation by the com-
    menter is consistent with CERCLA guidance for preparing  such cost estimates, which calls for
    accuracy within the range of -30 to +50 percent.

    The commenter specifically identified Construction Management and Contractor Overhead & Profit
    costs as being "very high".  These cost elements are computed on a percentage basis. The percent-
    age rate used was developed from INEL-specific construction cost history.

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    Costs were refined in preparation for public meetings with the EM Site-Specific Advisory
    Board-INEL. These refined estimates include additional specific items, such as foundation prepara-
    tion and acquisition and transportation of materials, thus reducing the contingency factor percentage.
    These refinements result in estimates of $1.97 million for  SL-1 and $1.45 million for BORAX-I.
    Although these estimates are better than those that appeared in the proposed plan, they are still fairly
    rough.  Anticipated actual costs can not be presented until remedial design is complete.

7.  Comment:  Three commenters expressed opinions that Alternative 2 is the best choice.

    Response:  The agencies agree that Alternative 2, containment by capping with an engineered bar-
    rier comprised primarily of natural materials, is the preferred alternative based on effectiveness,
    cost, and the other evaluation criteria discussed in the proposed plan and Record of Decision.
    Consequently, this alternative appears in the Record of Decision as the selected remedial action for
    both the SL-1 and the BORAX-I burial grounds.

8.  Comment:  Two commenters favor Alternative 3. One commenter felt that Alternative 2 would
    leave us vulnerable to natural disasters, vandalism, or cutbacks in monitoring. The other com-
    menter  was  worried that the INEL, being situated above the Snake River Plain Aquifer and in an
    earthquake sensitive area, is "a disaster awaiting its own fulfillment."

    Response:  The excavation and removal discussed in Alternative 3 does return the sites to natural
    conditions; however, this remedy essentially moves the problem from one location to another with-
    in the INEL with significant risks to workers and the public and at very high cost. This action
    would only forestall a timely decision regarding the final  disposition of the wastes and would not
    alleviate the commenters' concerns. The prediction regarding "a disaster awaiting its own fulfill-
    ment", refer: to events such as earthquakes and other natural disasters.  A very small probability
    exists that such events could occur; therefore design features such as slope minimization will be
    evaluated and incorporated into the engineered covers as determined appropriate during the
    Remedial Design phase.

9.  Comment:  One commenter stated that the Special Power Excursion Reactor Test I reactor pro-
    gram was also concluded with a destructive test similar to the BORAX-I  experiment. The com-
    menter concludes that this experiment must also have resulted in contaminated debris and soil, and
    wanted  to know  why it is not included in any proposed clean-up plan.

    Response: The  Special  Power Excursion Reactor Test  I facility was decommissioned in 1964.  The
    reactor pit was demolished in 1985 and the site  returned to its original state. No known contami-
    nated debris remains at the site.  The Power Burst Facility reactor was built just north of the Special
    Power Excursion Reactor Test I location, and the facility is now known as the Power Burst Facility
    Reactor Area. The only  two remediation sites identified within this facility are a seepage pit (site
    code PBF-11) and a leach pond (site code PBF-12).  Both have received no further action recom-
    mendations.
                                             A-12

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10. Comment: One commenter expressed the opinion that taxpayers money is being wasted by pro-
    ducing publications and expending funds on "low risk projects."

    Response: The SL-1 and BORAX-I burial grounds can not be considered low risk projects in view
    of the risks estimated in the baseline risk assessment and summarized in the proposed plan. In
    response to Superfund guidance and the INEL Community Relations Plan, the agencies have direct-
    ed that program funds be used to communicate information concerning the investigations to the
    public.  The preparation of the INEL Reporter, fact sheets, and proposed plans are traditional meth-
    ods of updating citizens on project specifics.  The object of these publications is to describe how
    the agencies are approaching the work outlined in the Federal Facility Agreement and what new
    information is learned about the sites.  The invitation for citizens to interact with the agencies con-
    cerning this process is an important part of finding out what citizens think of the agencies' recom-
    mendations. The result of interaction between the public and the agencies is the formulation of a
    decision that considers the issues raised by citizens through a fair and reasonable process.

11.  Comment: One commenter stated that trials should be conducted to determine if scraping surface
    soils and extracting the uranium-235 results in recovery of significant amounts of uranium.  If suc-
   cessful,  the method should be  applied more extensively at the sites because recovery of the uranium
   would return it to secure storage and reduce the long-term impacts from these sites.

   Response: The commenter referred to the use of technologies which could be used to extract ura-
   nium-235 from surface soils if soils were scraped from the areas surrounding the burial grounds.
   The technology being referred to is called "soil washing". This technology has been demonstrated
   for the removal of uranium from soil, but was not considered for application at either SL-1 or
   BORAX-I. As described in Section 11, the surface soil associated with the SL-1 burial ground will
   not require remedial action.  In addition, uranium was not identified as a contaminant of concern in
   SL-1 surface soils.  This technique for BORAX-I is described below.

   The effectiveness of soil washing is dependent on site-specific soil characteristics and the chemical
   behavior of contaminants in the environment. Soil washing studies performed at the Hanford site
   indicated that uranium would typically be concentrated in the smaller soil size fractions (silts and
   clays).  Therefore, removal of uranium from BORAX-I soils would initially require separation into
   specific  soil size fractions such as gravel, sand, silt, and clay. The larger soil  size fractions, gravel
   and sand, would then be analyzed and either returned to the site or treated, depending on the results
   of the analysis. If necessary, mechanical agitation or scrubbing would be used to physically remove
   uranium from the surfaces of the  larger size soil fractions. The smaller soil size fractions, most
   likely to contain the majority of uranium, would then be leached by a chemical extractant such as
   sulfuric acid.  Studies have shown such leaching  processes can reduce uranium concentrations in
   the smaller soil size fractions to levels between approximately 20 and 70 parts per million. The
   chemical extractant and wash water would require additional treatment to remove uranium extract-
   ed from the soils.

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    Separating uranium from the soil surrounding BORAX-I is not considered feasible based on the
    extremely low concentrations anticipated in the surface soils, and the small mass of uranium actually
    contained in the soil. Scraping contaminated surface soils would result in considerable mixing of the
    existing gravel cover and the clean soil immediately beneath the  contaminated soil.  Assuming the
    entire mass of unrecovered uranium at BORAX-I, about eight pounds (3.7  kilograms), is uniformly
    distributed throughout the 84,000 square feet of potentially contaminated soil area, removal of the top
    foot of soil and gravel from this area would result in a  maximum uranium concentration of one part
    per million. For the sake of argument, assuming  the smaller soil size fraction represented 20 percent
    of this volume and was effectively separated by the initial soil washing stage, then a maximum of
    only five parts per million could be obtained. Assuming the entire eight pounds (3.7 kilograms) were
    distributed in a much smaller area, perhaps one-sixth the entire 84,000 square feet, the uranium con-
    centration would be approximately six parts per million.  If the smaller soil size fraction represented
    20 percent of this volume and were effectively  separated by the initial soil washing, then a maximum
    of 30 parts per million could be obtained.  Such low concentrations would not be amenable to effec-
    tive leaching in the final stage of the  soil washing process.

    Soil washing could be effective  for removing larger particles if the majority  of uranium were not in the
    form of uniformly distributed fine particles. However, historical documentation indicates the fuel frag-
    ments (larger particles) were collected from the surface  soils and the majority of remaining contamina-
    tion interred in the reactor foundation. Therefore  the actual mass  of uranium in the BORAX-I surface
    soils is probably significantly less than the unrecovered  eight pounds (3.7 kilograms).

    The focused remedial investigation/feasibility  study performed for SL-1 and BORAX-I was based
    on remedial actions identified in previous CERCLA Records of Decision, and although soil wash-
    ing technology exists and is currently in use under the EPA Superfund Innovative Technology
    Evaluation Program, the technology  has not been specified for use in previous CERCLA Records
    of Decision involving radionuclide contaminated soils.

12.  Comment: One commenter suggested  that  selection of an alternative should be deferred until the
    methods and costs associated with the Pit 9 action are  available. The commenter felt the cost esti-
    mates for SL-1 and BORAX-I and the decision for these two sites could change if some of the
    waste could be processed through the Pit 9 treatment facilities.

    Response: The  situation at Pit 9 is sufficiently different from that at the SL-1 and BORAX-I burial
   grounds to eliminate the possibility of similar treatment. The limited production tests at Pit 9 are
   directed at transuranic wastes in concentrations greater than 10 nanocuries per gram; wastes at the
    SL-1 and BORAX-I burial grounds are  described in terms of picocuries, three orders of magnitude
    smaller. In addition, Pit 9 wastes include hazardous substances  and some  mixed waste, unlike the
   SL-1 and BORAX-I burial grounds where radionuclides are the  only contaminants of concern.
    Preliminary information regarding cost  and effectiveness of the limited  production tests being per-
    formed for the Pit 9 treatments will not  be available before January,  1997. The agencies do not

                                             A-14

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    anticipate that delaying this remedial action until the Pit 9 cost and effectiveness data are available
    will alter their preference for capping the sites as described in Alternative 2 of the proposed plan.

 13. Comment:  One commenter stated that partial cleanup including ground scraping and removal of cont-
    amination in excess of 10 CFR 61 Class A limits should be considered as an additional alternative.

    Response:  Removal of contaminated surface soil is a potential aspect of the final remedial design
    phase.  Three potential options for disposition of contaminated surface soils surrounding the burial
    grounds were identified in the remedial investigation/feasibility study.  These options include:

    •   No action or restricted access

    •   Removal followed by disposal at Radioactive Waste Management Complex

    •   Consolidation near the location of buried waste for inclusion beneath the protective cover.

    10 CFR 61 defines the criteria under which the Nuclear Regulatory Commission issues licenses for
    land disposal of radioactive waste.  The disposal at the SL-1 and BORAX-I burial grounds took
    place prior to the effective date of 10 CFR 61, so the licensing requirements do not apply.

14. Comment:  Two commenters indicated that future land use scenarios should be established before
    decisions are made so that exposure scenarios could be determined on the basis of realistic project-
    ed land use.

    Response:  The INEL is in the process of establishing land use scenarios for areas surrounding Site
    facilities. Certain areas may be designated for future industrial land use; these scenarios will be used
    to form the basis of risk calculations in the future.  In the meantime, the agencies have decided to
    take the cautious approach to protect workers, the public, and the environment by applying the most
    protective land use scenarios in current risk assessments.

15. Comment:  One commenter expressed the opinion that results of capping studies from the old
    dairy farm and other studies should be used in this evaluation.

    Response:  INEL-specific research  involving capping design Has been included in the preliminary
    conceptual designs of the caps evaluated for SL-1 and BORAX-I.  The Environmental Science and
   Research Foundation is currently conducting cap design experiments at the INEL. These experi-
   ments, called the Protective Cap/Biobarrier Experiments, focus on "low-cost, natural systems to
   effectively isolate municipal, industrial, and low-level radioactive wastes and contaminated soil sur-
   faces  from the environment, for centuries." The results obtained thus far in the experiments were
   incorporated in the Uranium Mill Tailings Remedial Action type cap design presented in the reme-
   dial investigation/feasibility study report.  This included a 5-foot (1.6-m) soil layer for water bal-
   ance,  a  1.5-foot (45-cm) rock/cobble layer in combination with a 1-foot (30-cm) gravel layer for

                                             A-15

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    biotic control.  During the remedial design phase, such INEL-specific information will be included
    in the final cap design.

 16. Comment:  One commenter demands that Alternative 3 be selected for SL-1 and BORAX-I and
    that no further out-of-state shipments of radioactive waste be "allowed to be deposited there".

    Response: Alternative 3 is the removal of wastes from the burial ground with disposal at the INEL's
    Radioactive Waste Management Complex.  Removal and disposal only relocates the contamination
    within the ENEL at a high cost and potentially high risk to workers and the public; it does not eliminate
    the problem.  Alternative 2, covering and controlling the contamination through time while radioactive
    decay decreases the risk,  is a safer and more cost-effective approach. The SL-1 and BORAX-I sites
    have never received waste shipped into the state from other sources. To receive information or ask
    questions concerning possible transportation of waste to the INEL from out-of-state, citizens can call
    the INEL's toll-free number, 1-800-708-2680, to request additional details and assistance.

 17. Comment:  One commenter suggested that "debris treatment" should  be utilized to reduce volumes
    of mixed waste.

    Response: Mixed wastes have not been identified at  either burial ground.  Also see responses 11,
    12, and 13.

 18. Comment:  One commenter asked what considerations to reduce volumes of contaminated soils
    were being exercised.

    Response: Under the preferred alternative, capping with an engineered barrier, contaminated sur-
    face soils will be consolidated at BORAX-I based on  field screening and sample data acquired dur-
    ing the remedial design phase of the remedial action.  No other applicable minimization efforts
    have been identified.

                          A.4  Comment and Response Index

    Because comments are summarized in the  Responsiveness Summary for response, an index is
included to assist in identifying responses to specific comments. All oral comments, as received at the
public meetings, and all written comments are included verbatim. Each comment is coded with a W,
meaning a written comment, or a T for an oral comment transcribed during the public meetings.  Seven
people submitted written comments and three rendered oral comments during the meeting. A total of
19 comments were  received.
                                            A-16

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    To locate a response to a specific comment, identify the comment on the index, note the associated response number and page num-
ber, and turn to that response in the Summary of Comments and Responses in Section A.3.
Table A-3. Index of comments.
Response
Code Number
W-l 7
W-2 6, 7
W-3 9
W-4 10
W5 8
W-6 8, 16
W-7 14, 17, 18
T-l 2
T-2 2
T-3 1 1
Comment
Alternative 2 is adequate.
Excellent & interesting reports. Cost estimates seem high! I agree with the preferred alternatives. Estimated costs for capping landfills seem very high; if design
is simple and clear, I think competitive bidding (fixed price) should reduce estimated costs shown here in by (25 to 50) %. In particular, const, mg't &
contractor ov'h'd & profit seem very high compared to the direct "Construction of Cap" costs. Possibly this is due to high liability insurance costs, or other job
risk costs that I am not familiar with. At any rate, 1 recommend "working" the cost reduction possibilities very hard.
The SPERT 1 reactor program was also concluded with a destruct test which occurred in the early to mid 1960s, similar to the BORAX-I destruct test.
The SPERT 1 destruct test must have resulted in contaminated debris and soil. Why is SPERT I not included in any proposed clean-up plan?
Why do you continue to waste taxpayers $. Your publications plus the expenditures directed towards low risk projects are a total waste. You guys are out-of-control.
1 favor Alternative 3 as the only permanent solution for decontamination of the SL-1 and BORAX-I sites. 1 fear that Alternative 2 would leave us vulnerable
to natural disasters, vandalism, or cutbacks in monitoring in the long run.
The IN EL. being situated above the Snake River Aquifer and in an earthquake sensitive area, is a disaster awaiting its own fulfillment. I demand that
Alternative 3 be instated and that no further out-of-state shipments of radioactive waste be allowed to be deposited there.
• Utilize "debris treatment" for reducing vol. of mixed waste
• Closure goals must be established considering future "land use" criteria
• DOE must establish "land use" criteria for the INEL
• What considerations are being exercised to minimize volume of contaminated soils to be disposed.
There's been a lot of discussion on these plumes, and what might reach the groundwater. Of course, that's one of the major things that the citizens of the
State of Idaho are concerned about. 1 heard tonight that it was going to be 10,000 years before the heavy metals, U-235 would reach the groundwater by
modeling by a code named G '/SCREEN. My understanding is there's been very little benchmarking of these codes done. Last summer there was what
was called the aquifer stress lest to try and do some benchmarking. There's been considerable work to validate codes - we've heard about the NRC -
to validate computer codes to make sure that they predict what's right. The codes that are being used at the INEL are not benchmarked. They are not
validated. And 1 think we're getting the cart before the horse on this and going out and taking actions before we really know what we've got as far as
contaminants. Let's get some good computer codes. Let's gel some good modeling. 1 see fate and transport modeling in here. And again, it's the old adage
of "garbage in, garbage out." And I think (hat's what we've got here. We don't know the ion exchange of these metals between the soil. Conservative values
most largely are being used, but there's a lot of unknowns, and there needs to be some overall benchmarking of those computer codes that are being used similar
to what the NRC has done with the RELAP models, the Skadat (sic) (TRAC?) models. We talk about us spending huge sums of money on reactor safety, and
we're talking about risk here supposedly, according to the EPA of 5 in 10,000. This is much greater than what the NRC is saying you're going to have from
some of these spare reactor accidents. So let's get some codes validated and benchmarked, and then let's proceed with what we have - either a No Action or
Alternative Actions.
I heartily agree with what's just been said when it comes to the need for the improvements that he's (Robert Wadkins, comment T- 1 ). There's certainly a
real need there.
According to DOE's reports regarding remediation of these sites, considerable uranium-235 remains unrecovered - about two pounds at the SL-1 site and
about eight pounds at the BORAX-I site. Because of U-235's very long half-life, as a practical matter it will never decay away, and there is enough there to
make one or more nuclear weapons. With today's improved equipment, scraping an inch or two of topsoil from the ground surface and passing the scrapings
and any other appropriate excavated soil through soil decontamination equipment and a heavy metal particle separation device could probably recover a
considerable amount of the uranium and other radionuclides for disposition elsewhere. And before replacing more cover material, it appears that this should
be tried on a limited scale and used more extensively if the trials prove successful. Removal of uranium-235 will not only restore this uranium to secure
storage, it will also decrease these sites' long-term impacts that will not be reduced appreciably during the limited lifetime of an engineering barrier.

Page
Number
A-ll
A-10
A-ll
A-12
A-ll
A-ll
A-15
A-14
A-15
A-6
A-6
A-12
 T-4
What water transport time (from the surface to the aquifer) and what flow rate in the aquifer were used in the evaluation? Since these are uncertain, what
extremes were considered in the uncertainty analyses? What kind of uncertainty analyses were done, and what were the resultant extremes of dosage
imposed by the more significant radionuclides in the aquifer plumes from SL-1 and BORAX-I?
                                                                                                                                            A-7

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Table A-3.  (continued)
Code
         Response
         Number    Comment
Page
Number
T-S      4            Will the SL-1  contaminant plume in the aquifer overlap the plume from BORAX-I? Will these plumes overlap the plume from the previously evaluated
                      RWMC Pad A? (Pad A is downstream from BORAX-I and SL-1. And for Pad A. DOE previously concluded that a cap will be installed over about
                      18,000 55-gallon drums and 2,000 4x4x7 foot boxes of alpha-contaminated Rocky Flats waste that is to be left buried there.) My concern is the combined
                      impact of these on a future member of the public since it is the combined impact on the maximally exposed individual that counts.  And this combined
                      impact is what should be considered in deciding what to do about the waste at each disposal site.  In addition, the following  locations emit plumes that may
                      overlap the plumes from SL-I and BORAX-I and Pad A:  waste buried from 1984 through the end of RWMC waste disposal operation, the Test Reactor
                      Area, the Idaho Chemical Processing Plant, and the portion of the RWMC that was used for rad waste disposal from 1952 to 1984. The impact of all of the
                      plumes that overlap should be considered in reaching a conclusion regarding the appropriate remediation action for waste at any one of the locations.
                      Moreover, the extent of time in the future that should be addressed should not be restricted to a relatively short time period like 100 years or 1,000 years but
                      should extend much further to at least 10,000.                                                                                                                        A-9
T-6      5            These sites are essentially inactive disposal sites for spent fuel, transuranic waste, greater than Class C waste, and  low level waste.  There are laws against disposal
                      of such waste - that is, 40 CFR 193 and the Low Level Waste Policy Act of 1985 - unless the waste can be shown  to be  adequately confined for at least 10,000
                      years.  How are these require nents accounted for?                                                                                                                    A-9
T-7       I            Considering the Nuclear Regulatory Commission scenarios regarding a future inadvertent intruder onto an in-future abandoned waste disposal site - that is, the
                      well drilling scenario, basement excavation and home construction, farming and excavation and discovery of buried articles  - what  would be the maximum
                      dosage to such and intruder at the times of maximum dosage regardless of how far these are in the future? Or at least to 10,000 years?  How do these dosages
                      compare with DOE and NRC dosage limits for a future inadvertent intruder onto an unrecognized abandoned rad waste facility?                                              A 6
T-8       12          The planned cleanup of Pit 9 could provide experience-derived information on which to base cost estimates for cleaning up the SL-1 and BORAX-I sites.
                      And changes to their cost estimates could influence the decision regarding which remediation alternative to pursue.  Consideration  should be given to deferring
                      the final decision regarding these issues until Pit 9 cleanup has progressed sufficiently to permit better assessment of the methods and costs  that should be
                      involved in their cleanup.  Also possibly some of the waste generated in these cleanups  could best be prepared for disposal by  processing them through the Pit 9
                      treatment facilities.                                                                                                                                                A-14
T-9       13          The Site Disposition Alternatives considered apparently only one involving waste removal  - removal of all contaminated materials, the most expensive of all.
                      Partial cleanup involving the above mentioned ground scraping plus removal of materials contaminated beyond 10 CFR 61  Class A limits deserves consideration
                      as an alternative. Such a partial cleanup could substantially reduce the very long half-lived portion of these sites' radioactivity plumes in the aquifer and  their
                      impacts on future inadvertent intruders, and the cost should be substantially less than that of total cleanup.                                                                  A-14
T-10     14          I still have a question on the land use and the industrial scenario, and I think that any further action or closing out or accepting of any alternatives be delayed until
                      we get a land use plan for the INEL so we know where we're going and what we're going to do with it. The one in ten scenario - again I believe on the industrial,
                      the risk scenario, I believe there's a direct exposure driving that, and it's a direct exposure to an individual with no capping, no asphalt, or something like that.
                      I believe it needs to be a realistic scenario on the industrial scenario, and that factors again into this land use.  I think that we're just sitting here spinning our wheels
                      and perhaps spending a lot of money along with the wheel spinning if we proceed with some of these alternatives before we've got a land use plan in place for
                      these areas that we're considering tonight, and perhaps even the total INEL.  The soil consolidation variables that  were mentioned, I think that if you're picking
                      up any contamination out there under the  EPA criteria, if you're going  to say that it's going to be  exposed and there's no cover on it, you're going to have to
                      consolidate the soil. I don't think you've got any choice with the cesium-137 out there.                                                                                  A-14
T-11     15          The other question I have, is there's a number of studies going on various capping things on what was called the old dairy farm out there. I don't know what those
                      studies are called, but they've done a number of studies and looking at animals burrowing  into the soil and things like that.  I think those should be factored in.
                      Here there's a lot of research going on out there, and I keep seeing these things and none of it factored in here. Here we're  proposing some things, that of capping
                      and that - let's use what work we've done and what research we've done out there.                                                                                       A-15
T-12     7           Looking at and having read this  and having a pretty good grasp about the natural sciences, having degrees in it, 1 think the Containment Number 2 would be in my
                      opinion the Preferred Alternative in this situation.  I think  that No Action  is -1 think that we created this mess in our lifetime,  we need to clean up this mess in our
                      lifetime.  I don't think we need to leave it for future generations. Plus I think that there is  a good possibility that we could have airborne paniculate activity with
                      this thing as far as with wind erosion, and that is really what I'm mostly concerned.about in this situation, in all of these sites, really, is the  possibility of having
                      wind  erosion take place. I think that in any of these sites I would prefer that nothing that is contaminated  is ever touched again and everything is left in place.
                      I you're going to mound on top of it sufficient weight where the shaking of the earthquake - I mean, there is a fault line that is running through this area  - you
                      wouldn't worry about it sloughing off and creating even a larger problem than is already there. I  think it'll indicate to whoever happens upon it in the  future
                      generations, it will indicate to them that this wouldn't be a proper place to put a foundation for a  home or put a garden in.  Whether we are  able to communicate
                      to those future generations or not,  in 400 years Lord knows where we'll be as far as the human race, we all know that, so that's about all I have to say  about that.                A-11

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          Appendix B
Administrative Record File Index
              B-1

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B-2

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                       Idaho National Engineering Laboratory
          Administrative Record File Index for the Track 2 Scoping of the
                    ARA-II SL-1 Burial Ground OU 5-05 and 6-01
                                          6/26/95

File Number

AR1.1       Background

       Document #:  EGG-GEO-10068
       Title:        A Modeling Study of Water Flow in the Vadose Zone beneath the RWMC
       Author:      Baca, R.G.
       Recipient:    N/A
       Date:        01/01/92

*Note: This Document is filed in the Pad A Administrative Record Binder
      Operable Unit 7-12 Volume I

       Document #:  EGG-BG-9175
       Title:        Independent Verification and Benchmark Testing of the Porflo-3 Computer
                   Code, Version 1.0
       Author:      Baca, R.G.
       Recipient:    N/A
       Date:        08/01/90

       Document #:  KJH-09-94
       Title:        Interviews with Darrell Hanni Regarding the SL-1 Burial Ground
       Author:      Holdren, K.J.
       Recipient:    Halford, V.E.
       Date:        07/06/94

•       Document #:  10022
       Title:        Record of Meeting with Roger G. Jensen, U.S.G.S., Regarding Depth to Aquifer
                   nearBORAX-I/SL-1
       Author:      VanDerpoel, G.
       Recipient:    N/A
       Date:        02/17/94

       Document*:  10023
       Title:        Record of Meeting with Dick Meservey, EG&G Idaho,  Regarding BORAX-I
       Author:      Tucker, J.
       Recipient:    N/A
       Date:        02/17/94
                                            B-3

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 File Number

 AR1.1

 •       Document #:
        Title:

        Author-
        Recipient:
        Date:

 •       Document #:
        Title:

        Author:
        Recipient:
        Date:

•       Document #:
        Title:
        Author:
        Recipient:
        Date:

•       Document #:
        Title:

        Author:
        Recipient:
        Date:

•       Document #:
        Title:

        Author:
        Recipient:
        Date:

•       Document #:
        Title:

        Author:
        Recipient:
        Date:

•       Document #:
        Title:

        Author:
        Recipient:
        Date:
                       ARA-fl SL-1 Burial Ground OU 5-05 and 6-01
                                            6/26/95
 Background (continued)

 10024
 Record of Meeting with Roger Wilhelmson, EG&G Idaho, Regarding Pipes in
 SL-1 Burial Ground
 Meadows, G.
 N/A
 04/15/94

 10025
 Record of Meeting with Eddy Chew, DOE-Idaho Regarding SL-1 Burial Ground
 Pipes
 Meadows, D.
 N/A
 04/14/94

 10026
 Record of Meeting with Glenn Briscoe, Regarding SL-1 Burial Ground
 Meadows, D.
 N/A
 01/25/94

 10027
 Record of Meeting with Craig Kwamme, LITCO, Regarding Basis for RWMC
 Disposal Costs
 Vetter, D.
 N/A
 12/02/94

 10028
 Memo of Conversation with Richard Green, Regarding Pipes in the SL-1 Burial
 Ground
 Holdren, K.J.
N/A
 04/14/94

 10133
 Support Documentation: Estimation of Uranium-235 Surface Soil Concentrations Based
on Mass Unrecovered at the BORAX-I Ruria' Ground
R. Filemyr
J. Holdren
08/30/95

 10134
Errata for the Remedial Investigation/Feasibility Study Report for Operable Units 5-05
and 6-01 (SL-1 and BORAX-I Burial Grounds)
R. Filemyr
N/A
08/30/95
                                              B-4

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        Document #:  10135
        Title:        Support Documentation: Annual Dose Calculation for Selected Scenarios at the SL-1
                    and BORAX-I Burial Grounds
        Author:      R. Filemyr
        Recipient:    J. Holdren
        Date:        08/30/95

        Document*:  10136
        Title:        SL-1/BORAX-I Class C Waste Equivalency Determination
        Author:      R. Filemyr
        Recipient:    J. Holdren
        Date:        08/30/95

                       ARA-II SL-1 Burial Ground OU 5-05 and 6-01
                                           6/26/95

File Number

AR1.7             Initial Assessments

        Document #:  2984
        Title:        ARA-06, ARA H SL-1 Burial Ground
        Author:      N/A.
        Recipient:     N/A
        Date:        09/15/86

•       Document #:  2629
        Title:        BORAX-02, BORAX-I Burial Site
        Author:      N/A
        Recipient:     N/A
        Date:        10/03/86

AR3.8             Risk Assessment

        Document #:  MISC-94001
        Title:        Preliminary Baseline Risk Assessment for the OU-5-05 and 6-01, SL-1 and
                    BORAX-I Burial Grounds RI/FS
        Author:       N/A
       Recipient:     N/A
       Date:        10/01/93

•       Document #:  5662
       Title:        Overview of Exposure Scenarios for the Baseline Risk Assessment for the
                    OU 5-05 and 6-01, SL-1  and BORAX-I Burial Grounds RI
       Author:       N/A
       Recipient:     N/A
       Date:        10/01/93

       Document*:  INEL-95/103 Rev 2
       Title:         ARA Windblown Area Risk Evaluation
       Author:       D. Jorgensen
       Recipient:     N/A
       Date:        09/07/95
                                             B-5

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        Document*:   10137
        Title:         Assessment of Surface Soils Surrounding the SL-1 Burial Grounds
        Author:       K. J. Holdren
        Recipient:     N/A
        Date:         October, 1995

                       ARA-II SL-1  Burial Ground OU 5-05 and 6-01
                                            6/26/95
 File Number

 AR3.10
 •      Document #:
       Title:

       Author:
       Recipient:
       Date:
 Scope of Work

EGG-ER-10998
Scope of Work for Operable Units 5-05 and 6-01  (SL-1 and BORAX-I Burial
Grounds) Remedial Investigation Feasibility Study (RI/FS)
Halford, V.E.
N/A
03/01/94
AR3.12
       Document #:
       Title:
       Author:
       Recipient:
       Date:

       Document #:
       Title:

       Author:
       Recipient:
       Date:
Remedial Investigation/Feasibility Study

OPE-ER-157-94
Transmittal of the Draft Remedial Investigation/Feasibility Study Report for
Operable Units 5-05 and 6-01 (SL-1 and BORAX-I Burial Grounds RI/FS);
Volume 1 of 2
Lyle, J.L.
Pierre, W.; Nygard, D.
06/15/94

INEL-95/0027
Remedial Investigation/Feasibility Study Report for Operable Units 5-05 and
6-01 (SL-1  and BORAX Burial Grounds)
Holdren, K.J.; Filemyr, R.G.; Vetter D.W.
N/A
03/01/95
AR4.3              Proposed Plan

•      Document #:  10011
       Title:         Proposed plan for Operable Units 5-05 and 6-01 Stationary Low-Power
                    Reactor-1 and the Boiling Water Experiment-I Burial Grounds
       Author:       DOE, EPA, IDHW
       Recipient:     N/A
       Date:         05701/95
                                             B-6

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