Superfund Record of Decision Savannah River Site (USDOE) OU 16 Old F Area Seepage Basin (904-49g) Aiken Sc


                                    EPA/ROD/R04-97/205
                                    1997
EPA Superfund
     Record of Decision:
     SAVANNAH RIVER SITE (USDOE)
     EPA ID: SC1890008989
     OU16
     AIKEN, SC
     05/14/1997

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                                                                                  WSRC-RP-96-872
                                                                                  Revision 1.1 Final
                                                                                  March 1997
                                                  DISCLAIMER
This report was prepared by Westinghouse Savannah River Company (WSRQ)  for the United States
Department of Energy under Contract No. DE-AC09-96SR18500 and is an account of work performed
under that contract.  Reference,  herein to any specific commercial product, process,  or services
by trademark, name, manufacturer or otherwise does not necessarily constitute or imply
endorsement, recommendation, or favoring of same by WSRC or by the United States Government or
any agency thereof.
                                   Printed in the United States of America

                                                 Prepared for
                                          U.S. Department of Energy
                                                      by

                                     Westinghouse Savannah River Company
                                            Aiken, South Carolina

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                    RECORD OF DECISION
            REMEDIAL ALTERNATIVE SELECTION (U)
            Old F-Area Seepage Basin (904-49G)
                      WSRC-RP-96-872
                    Revision 1.1 Final
                        March 1997
                    Savannah River Site
                  Aiken,  South Carolina
                       Prepared by:

           Westinghouse  Savannah River Company
                          for the
U.S. Department of Energy Under Contract DE-AC09-96SR18500
             Savannah River Operations Office
                  Aiken,  South Carolina

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DECLARATION FOR THE RECORD OF DECISION

Unit Name and Location

Old F-Area Seepage Basin (SRS Building Number 904-49G)
Savannah River Site
Aiken, South Carolina

The Old F-Area Seepage Basin (OFASB)(904-49G) is listed as a Resource Conservation and Recovery
Act (RCRA) 3004(u) Solid Waste Management Unit/Comprehensive Envirownental Response,
Compensation, and Liability Act (CERCLA) unit in Appendix C of the Federal Facility Agreement
(FFA) for the Savannah River Site. This operable unit includes the source unit (vegetation,
soils [basin and ditchline], pipeline, and pipeline soils) and the groundwater unit.

Statement of Basis and Purpose

This decision document presents the selected remedial alternative for the OFASB located at the
SRS in Aikm South Carolina. The selected alternative was developed in accoirance with CERCLA,
as amended, and to the extent practicable, the National Oil and Hazardous Substances Pollution
Contingency Plan (NCP). This decision is based on the Administrative Record File for this
specific RCRA/CERCLA unit.

Assessment of the Site

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

Description of the Selected Remedy

The preferred alternative for the OFASB vegetation is to remove vegetation and dispose at an off
unit facility. This alternative will eliminate direct radiation hazard associated with
vegetation. Implementation of this alternative will involve removal of contaminated vegetation
from the OFASB and transporation disposal at an off unit disposal facility.

The preferred alternative for the OFASB pipeline and pipeline soils is institutoinal controls.
This alternative will restrict this land to future industrial use and limit access to the soil
which might expose future workers to low concentrations of hazardous constituents through use of
administrative controls such as site use and site clearance permit as well as access controls
such as filling or grouting pipeline manholes. Implementation of the institutional controls
alternative will involve both short- and long-term actions. For the short-term signs will be
posted at the waste unit which indicate that this arm was used for the disposal of waste
material and contains buried waste. In addition, existing SRS access controls will be used to
maintain the use of this site for industrial use only. In the long-term, if the property is
ever transferred to non-federal ownership, the U.S. Government, will create a deed for the new
property owned which will contain information in compliance with Section 120(h) of CERCLA. The
deed shall include notification disclosing former waste management and disposal activities as
well as remedial actions taken on the site, and any continuing groundwater monitoring
commitments. The deed notification shall, in perpetuity, notify any potential purchaser that
the property has been used for the management and disposal of radioactive materials and
hazardous substances. The deed shall also include deed restrictions precluding residential use
of the property. However, the need for these restrictions may be reevaluated in the event that
contamination no longer poses an unacceptable risk under residential use. In addition, if the
site is ever transferred to non-federal ownership, a survey plat of the area will be prepared,

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certified by a professional land surveyor, and recorded with the appropriate county recording
agency.

Along with the institutional controls identified above, the preferred alternative for the OFASB
soils  (basin and  (ditchline) is to remove the top two feet of soils in the ditchline and place
in the OFASB followed by in situ stabilization of the top two feet of basin soils and the
ditchline soils placed in the basin, and cover with a low permeability cap.  This alternative
will eliminate direct radiation hazards and minimize potential future impacts to the groundwater
from OFASB soils. Implementation of this alternative will involve excavation of contaminated
effluent ditchline soils to two feet below land surface, placement of these removed ditchline
soils in the OFASB, stabilizing the ditchline soils and the top two feet of contaminated soils
in the basin, and covering the basin area with a minimim 10 -5 cm/sec permeability cap.

The preferred alternative for OFASB groundwater is to continue existing institutional controls
and monitor the extent of the groundwater contaminant plume.  A groundwater mixing zone
application  (demonstration) has been approved by the appropriate regulatory agencies based on
data from monitoring wells around the OFASB and groundwater modeling.  This alternative will
demonstrate that remedial action objectives will be met, MZCLs will be achieved through the
groundwater aguifer, and MCLs will be achieved at the compliance point as described in the
approved groundwater mixing zone application.  Implementation of this alternative involves
installation and monitoring of groundwater wells as described in the groundwater mixing zone
application.

Statutory Determinations

Based on the OFASB RCRA Facilfty Investigation/Remedial Investigation (RFI/RI)  Report and the
Baseline Risk Assessment, the OFASB poses no significant risk to the environment but poses
significant risk to human health.  Therefore, treatment and capping is necessary for the OFASB
soils  (basin and ditchline), institutional controls are necessary for the OFASB pipeline and
pipeline soils, and monitoring of the existing groundwater consituents with the groundwater
mixing zone application.  The size, location of the waste unit, and contaminant levels preclude
a remedy in which contaminants could be excavated and heated effectively.

The selected remedy is protective of human health and the environment, complies with Federal and
State reguirements that are legally applicable or relevant and appropriate to the remedial
action, and is cost-effective.  This remedy utilizes permanent solutions and alternative
treatment (or resource recovery) technology to the maximum extent practicable,  and satisfies the
statutory preference for remedies that employ treatment that reduces toxicity,  mobility, or
volume as a principal element.  Section 300.430(f)(4)(ii) of the NCP reguires that a Five Year
Review of the ROD be performed if hazardous substances, pollutants, or contaminants remain in
the waste unit.  Since hazardous substances will remain on-site above health-based standards,
the three Parties have determined that a Five Year Review of the ROD for the OFASB will be
performed to ensure continued protection of human health and the environment.

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                      DECISION  SUMMARY
            REMEDIAL  ALTERNATIVE  SELECTION  (U)
            Old  F-Area  Seepage  Basin  (904-49G)
                      WSRC-RP-96-872
                     Revision  1.1  Final
                        March 1997
                    Savannah River Site
                   Aiken, South Carolina
                        Prepared  by:

            Westinghouse Savannah River Company
                          for the
U. S. Department of Energy Under Contract DE-AC09-96SR18500
              Savannah  River  Operations  Office
                   Aiken, South Carolina

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DECISION SUMMARY TABIiE OF CONTENTS
Section
Page
I. Site Operable Unit Name, Location, and Description 1
II. Operable Unit History and Compliance History 4
III. Highlights of Community Participation 4
IV. Scope and Role of Operable Unit Within the Site Strategy 5
V. Summary-of Operable-Unit-Characteristics 6
VI. Summary of Operable Unit Risks 7
VII. Description of the Considered Alternatives 14
VIII. Summary of Comparative Analysis of the Alternatives 18
IX. The Selected Remedy 20
X. Statutory Determinations 33
XI. Explanation of Significant Changes 33
XII. Responsiveness Summary 34
XIII. Post-ROD Document Schedule 34
XIV. References 35

List of Figures

Figure 1: Location of the Old F-Area Seepage Basin at the Savannah River Site 2
Figure 2 : Topographic & Water Table Potentiometric Map of the OFASB 3
Figure 3: Approximate Capping Area for the OFASB Preferred Alternative 23
Figure 4: Conceptal Layout After Implementation of the Preferred Alternative 24
Figure 5 : OFASB Post-ROD Document Schedule 34

List of Tables

Table 1: Signficant Risk Exposure for at Risk Receptors 8
Table 2 : Future On Unit Resident Conceptual Unit Model Risk Summary 11
Table 3: Future On Unit Worker and Visitor Conceptual Unit Risk Summary 12
Table 4: Comparative Analysis of Alternatives (Soils/Vegetation) 25
Table 5 : Comparative Analysis of Alternatives (Groundwater) 31

Appendix

A. Responsiveness Summary 37

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I. Site and Operable Unit Name, Location, and Description

The Savannah River Site (SRS) occupies approximately 310 square miles of land adjacent to the
Savannah River, principally in Aiken and Barnwell counties of South Carolina (Figure 1). SRS is
a secured U.S. Government facility with no permanent resident. SRS is located approximately 25
miles southeast of Augusta, Georgia and 20 miles south of Aiken South Carolina.

SRS is owned by the U.S. Department of Energy (DOE). Management and operating services are
provided by Westinghouse Savannah River Company (WSRC). SRS has historically produced tritium,
plutonium, and other special nuclear materials for national defense. Chemical and radioactive
wastes are by-products of nuclear material production processes. Hazardous substances, as
defined by the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) ,
are currently present in the environment at SRS. The Federal Facility Agreement lists the Old
F-Area, Seepage Basin (OFASB), 904-49G, (Figure 2) as a Resource Conservation and Recovery Act
(RCRA)/CERCLA unit requiring further evaluation using an investigation/assessment process that
integrates and combines the RCRA Facility Investigation (RFI) process with the CERCLA Remedial
Investigation(RI) to determine the actual or potential impact to human health and to
environment.

The OFASB is located within the SRS, approximately 600 feet north of F Area and 1 mile east of
Road C and is located in Aiken County. The Savannah River and associated swamps are located
approximately 6 miles west of the basin. The OFASB is located at the top of a gentle slope at
an elevation of 285 feet above mean sea level. The water table is approximately 75 feet below
ground surface in the area of the OFASB. Surface drainage is to the north toward Upper Three
Runs Creek which is at an elevation of 130 feet above mean sea level (155 feet below the basin
elevation).

The OFASB is designated as Building Number 904-49G and covers a total area of 1.3 acres.
Approximate dimensions of the OFASB are 200 fed by 300 feet with an earthen berm in the interior
dividing the basin into two areas. The basin remains open with growing vegetation and serves as
a wet weather pond. This unit also includes one effluent ditchline adjacent to the basin which
leads toward Upper Three Runs Creek and one process sewer line which fed the basin and has an
average depth of 9 to 10 feet below land surface and is about 800 feet in length. Groundwater
in the area has also been included m the unit assessment.

Between November 1954 and mid-May 1955, 9 to 14 million gallons of wastewater were discharged to
the basin which served as an unlined seepage basin for the purpose of reducing radioactive
substance concentrations. Wastewater included overhead condensates from evaporators, laundry
washwaters, non-reactor cooling water from F and H Areas, and possibly other chemicals.

Since 1955, the OFASB received occasional discharges of cooling waters and rainfall runoff.
During a three month period in 1969, spent nitric acid solutions used to etch depleted uranium
(M Area operations) were discharged (via tanker truck) to the basin. Wastewater disposal was
discontinued after the 1969 discharge. An estimated 1.8 curies (Ci) of radioactive releases
occurred during the use of the basin. Due to natural radioactive decay an estimated inventory
of less than 0.8 curies remains. Releases to the basin of various nonradioactive chemicals also
occurred during basin use. The inactive basin is currently fenced, open, and contains mature
trees, shrubs, and grasses. Standing water is present during wet seasons.

II. Operable Unit History and Compliance History

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Operable Unit History

The OFASB was first used between November 1954 and mid-May 1955. Nine to fourteen million
gallons of wastewater were discharged to the basin which served as an unlined seepage basin for
the purpose of reducing radioactive substance concentrations. Wastewater included overhead
condensates from evaporators, laundry washwaters, non-reactor cooling water from F and H Areas,
and possibly other chemicals.

An estimated 1.8 curies (Ci) of radioactive releases occurred during the use of the basin. Due
to natural radioactive decay an estimated inventory of less thin 0.8 curies remains. Releases to
the basin of various nonradioactive, chemicals also occurred during basin use.

The inactive basin is currently fenced, open, and contains mature trees, shrubs, and grasses.
Standing water is present during wet seasons.

Compliance History

At SRS, waste materials are managed which are regulated RCRA, a comprehensive law requiring
responsible management of hazardous waste. Certain SRS activities have required Federal
operating or post-closure permits under RCRA. SRS received a hazardous waste permit from the
South Carolina Department of Health and Environmental Control on September 5, 1995.

Module IV of the permit mandates that SRS establish and implement an RFI Program to fulfill the
requirements specified in Section 3004(u) of the Federal permit.

Hazardous substances, as defined by CERCLA, are also present in the environment at the SRS. On
December 21, 1989. SRS was included on the National Priorities List. This inclusion created a
need to integrate the established RFI Program with CERCLA requirements to provide for a focused
environmental program. In accordance with Section 120 of CERCLA, DOE has negotiated a Federal
Facility Agreement (FFA, 1993) with U. S. Environmental Protection Agency (EPA) and SCDPEC to
coordinate remedial activities at SRS into one comprehensive strategy which fullfils these dual
regulatory requirements.

Section V provides a detailed description of the operable unit, history of operation, and the
impact of releases to human health and the environment.

III. Highlights of Community Participation

Both RCRA and CERCLA require that the public be given an opportunity to review and comment on
the draft permit modification and proposed remedial alternative. Public participation
requirements are listed in South Carolina Hazardous Waste Management Regulation (SCHWMR)
R.61-79.124 and Sections 113 and 117 of CERCLA. These requirements include establishment of an
Administrative Record File that documents the investigation and selection of the remedial
alternatives for addressing the OFASB soils and groundwater. The Administrative Record File
must be established at or near the facility at issue. The SRS Public Involvement Plan (DOE,
1994) is designed to facilitate public involvement in the decision-making process for
permitting, closure, and the selection of remedial alternatives. The SRS Public Involvement
Plan addresses the requirements of RCRA, CERCLA and the National Environmental Policy Act SCHWMR
R.61-79.124 and Section 117(a) of CERCLA, as amended, require the advertisement of the draft

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permit modification and notice of any proposed remedial action and provide the public an
opportunity to participate in the selection of the remedial action.  The Statement of
Basis/Proposed Plan for the Old F-Area Seepage Basin (904-49G)(WSRC, 1996b),  which is part of
the Administrative Record File, highlights key aspects of the investigation and identifies the
preferred action for addressing the OFASB.

The FFA Administrative Record File, which contains the information pertaining to the selection
of the response action, is available at the EPA office and at the following locations:

       U.  S.  Department of Energy
       Public Reading Room
       Gregg-Graniteville Library
       University of South Carolina-Aiken
       171 University Parkway
       Aiken,  South Carolina 29801
       (803)  641-3465

       Thomas Cooper Library
       Government Documents Department
       Umversity of South Carolina
       Columbia,  South Carolina 29208
       (803)  777-4866

Similar information is available through the repositories listed below:

       Reese Library
       Augusta State University
       2500 Walton Way
       Augusta,  Georgia 30910
       (706)  737-1744

       Asa H.  Gordon Library
       Savannah State University
       Tompkins Road
       Savannah,  Georgia 31404
       (912)  356-2183

The public was notified of the public comment period through mailings of the SRS Environmental
Bulletin,  a newsletter sent to approximately 3500 citizens in South Carolina and Georgia,
through notices in the Aiken Standard, the Allendale Citizen Leader, the Augusta Chronicle, the
Barnwell People-Sentinel, and The State newspapers.  The public comment period was also
announced on local radio stations.

The 45-day public comment period began on September 17, 1996 and ended on October 31, 1996.  A
public comment meeting was held on October 15, 1996.  A Responsiveness Summary was prepared to
address comments received during the public comment period. The Responsiveness Summary is
provided in Appendix A of this Record of Decision.

IV.    Scope and Role of Operable Unit Within the Site Strategy

The overall strategy for addressing the OFASB was to:  (1) characterize the waste unit
delineating the nature and extent of contamination and identifying the media of concern  (perform
the RFI/RI);  (2)  perform a baseline risk assessment to evaluate media of concern, chemicals of
concern (COGS),  exposure pathways, and characterize potential risks; and (3)  evaluate and

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perform a final action to remediate, as needed, the identified media at concern.

The OFASB is an operable unit located within the Upper Three Runs Watershed. Several source
control and groundwater operable units within this watershed will be evaluated to determine
impacts, if any, to associated streams and wetlands. SRS will manage all source control and
groundwater operable units to minimize impact to the watershed. Based on characterization and
risk assessment information, the OFASB does not significantly impact the watershed. Upon
disposition of all source control and groundwater operable units within this watershed, a final,
comprehensive evaluation of the watershed will be conducted to determine whether any additional
actions are necessary. The OFASB investigation considered all unit specific groundwater.
Based on the investigation of the groundwater, the contamination in the water table agiufer is
apparently attributable to the OFASB wastes. The proposed action for the OFASB vegetation,
ditchline and basin soils, pipeline and pipeline soils, and groundwater is a final action.

V. Summary of Operable Unit Characteristics

Since 1955, the OFASB received occasional discharges of cooling waters and rainfall runoff.
During a three mouth period in 1969, spent nitric, acid solutions used to etch depleted uranium
(M Area operations) were discharged (via tanker truck) to the basin. Wastewater disposal was
discontinued after the 1969 discharge.

An estimated 1.3 curies (Ci) of radioactive releases occurred during the use of the basin. Due
to natural radioactive decay an estimated inventory of less than 0.8 curies remains. Releases to
the basin of various nonradioactive chemicals also occurred during basin use.

The inactive basin is currently fenced, open (bottom of basin is -10 feet below surrounding
land surface), and contains mature trees, shrubs, and grasses. Standing water is present during
wet seasons.

The conceptual unit model for the OFASB is depicted in Tables 2 and 3 which identify that
radionuclide contaminated soils are the primary contaminants which pose risk to both the future
resident and worker scenarios. These radionuclide risks are primarily associated with external
radiation exposure to basin and ditchline soils as well as ingestion of groundwater.

Media Assessment

The Data Summary Report for the Old F-Area Seepage Basin (U) (WSRC, 1995b), RFI/RI Report for
the Old F-Area Seepage Basin (U)(WSRC, 1995c), and Baseline Risk Assessment for the Old F-Area
Seepage Basin(U)(WSRC, 1995a) contain detailed analytical data for all of the environmental
media samples taken in the characterization of the OFASB.

Pipeline & Pipeline Soils

The RFI/RI Work Plan identified a data guality objective (DQO) process which determined that
characterization of the pipeline soils would be characteristic of the pipeline and pipeline soil
contaminants due to:

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• The length of operating history (less than 9 of batch wastewater disposal through the
pipeline),
• Pipe materials (verified clay pipe with a bell and hub design would not provide for
long term leak prevention),
• Minimal sediments (due to the short operating life of the OFASB pipeline sediments
are not expected to be present in any appreciable guantities), and
• Pipeline leakage (significant leakage is expected from historical service information
on the materials and pipe design used).

Based on these factors, it is believed that the probable condition is that any contribution of
contaminants from within the pipeline would not significantly increase the contaminant inventory
or affect the remedy selected (institutional controls) for the pipeline and pipeline soils.

Evaluations using modeling in the CMS/FS identified that pipeline soils did not pose a risk from
either direct exposure (pipe is an average of 10-12 fed below land surface) and activity levels
in the pipeline soils do not pose future impact to groundwater concerns.

Basin & Ditchline Soils

Analytical data indicate that significant impact to the soil media associated with the OFASB has
occurred from both radiological and nonradiological contaminants. Radiological contaminants
approach background at about 25 feet below the bottom of the basin. Nonradiological
contaminants are bound in the top 2 feet of the basin soils. Surficial soil contamination is
isolated to the confines of the fenced basin area and effluent ditchline areas.

Gross alpha concentrations in basin soils occur above background (i.e. >50 pCi/g) to a depth of
25 feet below ft bottom of the basin while nonvolatile beta concentrations above background
(i.e. >50 pCi/g) in basin soils occur to a depth of 15 feet below the bottom of the basin.
Although contaminants are present above background levels at depth, the predominant inventory of
radiological contaminants are bound in the top 2 feet of the basin soils. Treatability testing,
use of contaminant transport calculations, and evaluation of the decrease in contaminant
concentrations by depth indicate that radiological contaminants present below 2 feet pose no
potential future impact to the groundwater.

Major contaminants in the soils are cesium-137 and mercury. Cesium is present at a maximum
concentration of 1345 pCi/g at 0 to 1 foot below the basin bottom (53% of the cesium-137 is
found in the top 2 feet). Mercury is present at a maximum concentration of 35.6 mg/kg at 0 to 1
foot below the basin bottom (97% of the mercury is found in the top 2 feet).

Groundwater

Iodine-129, nitrate, strontium-90, and tritium have been detected above MCLs and uranium has
been detected above proposed MCIs based on groundwater monitoring data. Although radium has
been decreasing over time, it has also exceeded MCLs. The groundwater plume has been identified
from 8 local wells. The groundwater plume in the water table aguifer has migated beyond the
surface boundaries of the OFASB by mom than 200 feet toward the Upper Three Runs Creek which is
more than 2500 feet to the north of the OFASB.

VI. Summary of Operable Unit Risks

As a component of the remedial investigation process, a baseline risk assessment was prepared
for the OFASB. The baseline risk assessment consists of human health and ecological risk
assessments. Actual or threatened releases of hazardous substances from this site, if not
addressed by implementing the response action selected in this Record of Decision may present an

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imminent and substantial endangerment to public health welfare, or the environment. Summary
information for the human health and ecological risk assessments follows and has been summarized
in Table 1 below.

Human Health Risk Assessment

As part of the investigation/assessment process for the OFASB waste unit, a BRA was performed
using data generated during the assessment phase. Detailed information regarding the
development of constituents of potential concern (COPCs), the fate and transport of
contaminants, and the risk assessment can be found in the RFI/RI Report for the Old F-Area
Seepage Basin (U)(WSRC, 1995c) and the Baseline Risk Assessment for the Old F-Area Seepage Basin
(U) (WSRC, 1995a).

The process of designating the COPCs was based on consideration of background concentrations,
freguency of detection, the relative toxic potential of the chemicals, and chemical nutrient
status. COPCs are the constituents that are potentially site-related and whose data are of
sufficient guality for use in the risk assessment.

An exposure assessment was performed to provide an indication of the potential exposures which
could occur based on the chemical concentrations detected during sampling activities. The only
current exposure scenario identified for the OFASB was for the on unit visitor (researchers and
samplers). Conservative future exposure scenarios identified for the OFASB included future
occupational workers and future resident adult and children. The reasonable maximum exposure
concentration (95th percentile) value was used as the exposure point concentration.

Carcinogenic risks are estimated as the incremental probability of an individual developing
cancer over a lifetime as a result of pathway-specific exposure to cancer-causing contaminants
(carcinogens). The risk to an individual resulting from exposure to non-radioactive chemical
carcinogens is expressed as the increased probability of cancer occurring over the course of a
70 year lifetime. Cancer risks are related to the EPA Target Risk Range (TRR) of one in ten
thousand (1.0 x 10 -4) to one in one million (1.0 x 10 -6) for incremental, cancer risk at NPL
sites.

Noncarcinogenic effects are also evaluated to identify a level at which there may be concern
for potential noncarcinogenic health effects. The hazard guotient (HQ), which is the ratio of
the exposure dose to the reference dose (RfD), is calculated for each contaminant. HQs are
summed for each exposure pathway to determine the specific hazard index (HI) for each exposure
scenario. If the HI exceeds unity (1.0), there is concern that adverse health effects might
occur.

Current Land Use - Noncarcinogenic Hazards

The Baseline Risk Assessment shows that potential adverse noncarcinogenic health effects are not
likely to occur, because the sum of the His for the current on unit visitor scenario do not
exceed a value of one.

Current Land Use - Carcinogenic Risks

Under the current land use scenario, human health risks were characterized for the current on
unit visitor. The sum of the estimated nonradiological cancer risks were less than 1.0 x 10 -6.
Media evaluated include soil inside the basin, soil outside the basin, soil surrounding the
process sewer line, soil in the effluent ditchlines, associated airborne soil particulates,

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surface water and sediment in the stream/wetland, and groundwater.

Estimated radiological cancer risks for exposure due to external radiation is 4.5 x 10 -5
indicating that carcinogenic risk from the unit is limited. External radiation exposure risk
results from cesium-137 (95%) and cobalt-60 (2.5%) contamination. Other exposure pathways
evaluated estimated radiological cancer risk less than 1.0 x 1 -6.

The total of all estimated cancer risks for this exposure scenario is 4.6 x 10 -5 which
identifies external radiation as the primary exposure pathway (98%) for the current unit
visitor.

Future Land Use - Noncarcinogenic Hazards

The HIS exceed unity for both conservative future exposure scenarios (on unit worker and on unit
resident). His greater than unity for the future on unit worker were exceeded for ingestion of
groundwater primarily caused from elevated levels of manganese and lead. His greater than unity
for the future on unit resident were exceeded for ingestion of the groundwater due to manganese,
lead, and arsenic; ingestion of basin soil (mercury), and ingestion of fruits and vegetables
grown in basin soils (mercury). Manganese and arsenic are likely naturally occurring in
Southeast regional soils. Also, discharge records show that manganese was not a component of
any liguid discharge to the basin.

Future Land Use - Carcinogenic Risks

No significant risk for the future on unit "worker" due to nonradiological carcinogenic risks
greater than the Tarket Risk Range were identified. Exposure due to ingestion of groundwater
for the future on unit "resident" estimated significant nonradiological carcinogenic risks
greater than tbe EPA's Target Risk Range. This exposure was based on elevated arsenic
concentrations which are below area background concentration averages.

The ingestion of groundwater exposure pathway for the future on unit worker estimated
nonradiological carcinogenic risks within the EPA' s Target Risk Range based on beryllium and
arsenic. Ingestion of groundwater (beryllium), ingestion of surficial basin soft (PCB-1254),
ingestion of surficial effluent ditchline and process sewer line soil (arsenic), and ingestion
of fruits and vegetables grown in effluent ditchline and process sewer line soil (arsenic)
exposure pathways for the future on unit resident estimated nonradiological carcinogenic risks
within the EPA's Target Risk Range.

Exposure pathways for the future on unit worker which estimate significant, radiological
carcinogenic risks greater than the EPA's Target Risk Range are external radiation from the
basin soil (cesium-137), ingestion of groundwater (iodine-129, potassium-40), and
external radiation from the effluent ditchline soil (cesium-137). Exposure pathways for the
future on unit resident which estimate significant radiological carcinogenic risks greater than
the EPA's Target Risk Range are external radiation from the basin soil (cesium 137), ingestion
of fruits and vegetables grown in basin soils (cesium-137), external radiation from the effluent
ditchline soil (cesium-137), and ingestion of basin soil (plutonium-239).

Significant carcinogenic risks for the future on unit worker are driven by exposure from direct
radiation from the basin soils contaminated with cesium-137 and cobalt-60. Significant
carcinogenic risks for the future on unit resident are driven by exposure from direct radiation
from the basin soils contaminated with cesium-137, cobalt-60, radium-228, and europium-154.
These risks are estimated at 9.4 x 10 -3 for the future on unit worker and 1.6 x 10 -2 for the
future on unit resident.

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The total of all estimated cancer risks for the future on unit resident exposure scenario is
1.8 x 10 -2 which identifies external radiation as the primary exposure pathway (88%) for this
receptor. Ingestion of groundwater serves as a secondary risk contributor (8%).

The total of all estimated cancer risks for the future on unit worker exposure scenario is
1.0 x 10 -2 which identifies external radiation as the primary exposure pathway (96%) for this
receptor. Ingestion of groundwater serves as a secondary risk contributor (3%). Human health
risk tables (conceptual unit model) for the on unit resident (Table 2) and on unit worker and
visitor (Table 3) are provided below.

Ecological Risk Assessment

Based on characterization of the environmental setting and identification of potential receptor
organisms, a conceptual site model was developed to determine the complete exposure pathways
through which receptors could be exposed to COPCs.

Interpretation of the ecological significance of the unit-related contamination at the OFASB
indicated that there was essentially no likelihood of unit-related chemicals causing significant
impacts to the community of species in the vicinity of the unit. None of the COPCs identified
in soil at the OFASB are estimated to pose significant ecological risk based on their toxicity
at the concentration at which they are present.

Remedial Action Objectives

Remedial action objectives specify unit-specific contaminants, media of concern, potential
exposure pathways, and remediation goals. The remedial action objectives are based on the
nature and extent of contamination, threatened resources, and the potential for human and
environmental exposure. Initially, preliminary remediation goals are developed based upon
ARARs, or other information from the RFI/RI Report and the BRA. These goals should be modified,
as necessary, as more information concerning the unit and potential remedial technologies
becomes available. Final remediation goals will be determined when the remedy is selected and
shall establish acceptable exposure levels that are protective of human health and the
environment.

Constituents of potential concern are site- and media-specific, man-made and naturally occurring
inorganic and organic chemicals, pesticides, and radionuclides detected at a unit under
investigation. Constituents of concern are isolated from the list of constituents of potential
concern by calculating carcinogenic risks and noncarcinogenic hazard indices. A constituent of
concern contributes significantly to a pathway having a carcinogenic risk greater than 1 x 10 -6
and a hazard index greater than 1.0. Risk-levels at or above the upper-bound of the target risk
range (1 x 10 -4) are considered significant and these sites are expected to undergo
remediation. Risk levels between 1 x 10 -6 and 1 x 10 -4 require consideration for remediation.

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Mr. K. A. Collinsworth, FFA Project Manager
Federal Facility Agreement Section
Division of Site Engineering and Screening
Bureau of Solid & Hazardous Waste Management
South Carolina Department of Health and Environmental Control
2600 Bull Street
Columbia, SC 29201

Mr. J. L. Crane
SRS Remedial Project Manager
Federal Facilities Branch
Waste Management Division
U.S. Environmental Protection Agency, Region IV
Atlanta Federal Center
100 Alabama St. , S. W.
Atlanta, GA 30303

Dear Mr. Collinsworth and Mr. Crane:

SUBJECT: Transmittal of Copies of the Signed Records of Decision and Approved
Implementation Schedules

Enclosed is a copy of the signed Record of Decision for:

Old F-Area Seepage Basin (904-49G)
Central Shops Burning/Rubble Pit (631-6G)

Also enclosed is a copy of the approved Post-ROD Implementation Schedule for:

Old F-Area Seepage Basin (904-49G)

Questions from you or your staff may be directed to me at (803) 725-7032.

OD-97-0317

Enclosures
1. Record of Decision, Remedial Alternative Selection for the Old F-Area Seepage Basin
(904-49G)(WSRC-RP-96-872, Revision.1.1, March 1997)
2. Record of Decision, Remedial Alternative Selection for the Central Shops Burning/Rubble
Pit (631-6G)(WSRC-RP-96-873, Revision.1, April 1997)
3. Post-ROD Implementation Schedule for Old F-Area Seepage Basin (904-49G)

cc: with Enclosure 3 only
J. K. Lindler, SCDHEC - Columbia
J. T. Litton, SCDHEC - Columbia
G. K. Taylor, SCDHEC - Columbia
C. B. Warren, EPA-IV
C. A. Jones, EPA-IV
K. B. Feely, EPA-IV
SRS Administrative Record Files (Palmer, 730-2B)

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ARARs are those cleanup standards, standards of control, and other substantive requirements,
criteria, or limitations promulgated under federal, state, or local environmental law that
specifically address a hazardous substance, pollutant, contaminant, remedial action, location,
or other circumstance at a CERCLA site.  Three types of ARARs; action-, chemical-, and
location-specific; have been developed to simplify identification and compliance with
environmental requirements.  Action-specific requirements set controls on the desiqn,
performance, and other aspects of implementation of specific remedial activities.

Chemical-specific requirements are media-specific and health-based concentration limits
developed for site-specific levels of constituents in specific media.  Location-specific ARARs
must consider Federal, State, and local requirement that reflect the physioqraphical
and environmental characteristics of the unit or the immediate area.

There were no action-specific or location- specific ARARs relevant to establishing remedial
action objectives for the OFASB operable unit.  Only Uranium Mill Tailings Radiation Control Act
levels have been identified as a chemical-specific ARAR for the OFASB source unit and the waste
unit currently meets these levels.  Only MCLs (as identified in South Carolina R.61-58.5 State
Primary Drinking Water Regulations and Federal 40 CFR 141 National Primary Drinking Water
Regulations) have been identified as chemical specific ARARs for the OFASB groundwater unit.
The groundwater is not a current source of drinking water, however, all groundwater in South
Carolina is classified as GB under South Carolina R.61-68 Water Classification and Standards and
as such is required to be addressed in some manner  (State of South Carolina groundwaters must
undergo active remediation, to achieve MCLs unless a groundwater mixing zone is granted).   The
remedial action objectives identified below are met by the preferred remedy by ensuring that
through natural mixing zone processes the nearest groundwater receptor as defined in the
groundwater mixing zone application is not exposed to groundwater contaminated above MCLs and
access controls are in place through establishment of institutional controls to prevent exposure
to the groundwater plume.

The selected remedial action objectives for the OFASB operable unit are to:

       •    Prevent external exposure to radiological constituents,
       •    Prevent inhalation of radiological constituents,
       •    Prevent ingestion of soil or produce grown in soil with radiological constituents,
            and to
       •    Prevent or mitigate the release of constituents of concern to the groundwater.
       •    Prevent or mitigate the impact to the nearest groundwater receptor located at the
            Upper Three Runs Creek,
       •    Restore the aquifer through natural mixing processes and other processes (radioactive
            decay) to achieve MCLs throughout the groundwater plume  (groundwater mixing zone
            application modeling estimates that MCLs throughout the entire groundwater aquifer
            will be achieved in approximately 200 years), and
       •    Achieve, State Of South Carolina groundwater mixing zone objectives
            a)   control source to minimize addition of contaminants to the groundwater,
            b)   establish plume monitoring and compliance wells to ensure concentrations limits
                 and/or maximum contaminant levels established in the groundwater mixing zone
                 application, and
            c)   monitor to ensure contaminated groundwater remains on SRS until MCLs achieved
                 throughout the plume and to ensure groundwater area or plume is decreasing
                 concentrations.

VII.   Description of the Considered Alternatives

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As part of the investigation/assessment process for the OFASB waste unit, a CMS/FS was performed
using data generated during the assessment phase. Detailed information regarding the
development and evaluation of remedial alternatives can be found in the Corrective Measures
Study/Feasibility Study for the Old F-Area Seepage Basin (U)(WSRC, 1996a).

The RFI/RI and BRA indicate the OFASB soil poses significant risk to human health. External
radiation from basin soils for the current on unit visitor, and future on unit worker and
resident result in risk within the EPAs Target Risk Range for the current land use and
significant risk greater than the EPA's Target Risk Range for future use scenarios. Risks are
also associated with ingestion of groundwater for the future on unit worker and resident.
Therefore, a CMS/FS was conducted which included detailed analyses for soil/vegetation and
groundwater alternatives. The preferred alternative for the OFASB pipeline and pipeline soils
is institutional controls. This alternative will restrict this land to future industrial use
and limit access to the soil which might expose future workers to low concentrations of
hazardous constituents through use of administrative controls such as site use and site
clearance permits as well as access controls such as filling or grouting pipeline manholes.

VILA Description of the Considered Alternatives for the OFASB Operable Unit Soil/Vegetation

Five alternatives were evaluated for remedial action of the OFASB operable unit soil/vegetation.
Each alternative is described below.

Alternative SI - No Action

Under this alternative, no action would be taken at the OFASB. EPA policy and regulations
reguire consideration of a no action alternative to serve as a basis against which other
alternatives can be compared. Because no action would be taken and the OFASB would remain in
its present condition, there are minimal associated costs related to normal SRS maintenance
activities and there would be no reduction of risk. Since five year reviews of the remedy are
reguired, the estimated present value for these reviews and existing maintenance activities for
the next 30 years is $280,000.

Alternative S2 - Cap the Basin and Vegetation

This alternative involves the placement of effluent ditchline soils (~167 yards) and
contaminated vegetation (~25 cubic yards) into the OFASB and construction of a cap over the
OFASB. Initially, the waste unit would be prepared by clearing the trees, vegetation, fencing,
and other physical obstructions immediately surrounding the OFASB. Contaminated effluent
ditchline soils would be excavated and placed directly into the OFASB. Contaminated vegetation
would be segregated from uncontaminated vegetation and the contaminated vegetation would be
chipped and spread evenly over the OFASB soils.

The basin would then be backfilled and compacted to grade. After sufficient compaction, an
engineered cap would be constructed over the OFASB to minimize surface infiltration and reduce
the potential for contaminant migration.

The low permeability engineered soil cap will have a minimum thickness of 2 feet of compacted
low-hydraulic: conductivity soil (in-place saturated hydraulic conductivity of 1 x 10 -5 cm/sec
or less). The cap will also have an upper surface with a slope to promote surface runoff and
minimize surface erosion. The topsoil (vegetative soil layer will be placed at a minimum
thickness of 3 inches and will have the ability to survive and function with little or no
maintenance. The surface slope will also promote runoff and minimize surface erosion. The cap
would cover an area of approximately 3.5 acres (Figure 3). This alternative would reduce the
risks associated with direct radiation exposure and minimize future potential migration of

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contaminants to the groundwater.

Existing SRS institutional controls would remain in effect and the capping system would be
maintained resulting in a present value cost of $1,300,000.

Alternative S3A/B - In Situ Grout Soils To 2 Feet & Incinerate Vegetation at GIF
or Dispose of Vegetation Off Unit

This alternative involves the consolidation of effluent ditchline soils with the OFASB soils
followed by in situ grouting at the top 2 feet of the OFASB (~4,500 cubic yards) and effluent
ditchline soils (~167 cubic yards). Upon completion of in situ grouting, the OFASB would be
backfilled and compacted to grade, and an engineered cap as described in alternative S2 would be
constructed over the OFASB to minimize surface infiltration and reduce the potential for
contaminant migration. These alternatives (S3A/S3B) would reduce the risks associated with
direct radiation exposure and minimize, through grouting the most contaminated soils, future
potential migration of contaminants to the groundwater with minimal exposure to remediation
workers.

Alternative S3A includes the removal and chipping of the vegetation followed by incineration at
the SRS Consolidated Incinerator Facility (GIF). Existing SRS institutional controls would
remain in effect. Following remediation the unit would be maintained for a present value cost
of $2,100,000.

Alternative S3B includes the removal of the vegetation followed by transport and disposal off
unit. Existing SRS institutional controls would remain in effect. Following remediation the
unit would be maintained for a present value cost of $1,800,000.

Alternative S4A/B - Ex Situ Grout Soils to 2 Feet & Incinerate Vegetation at GIF
or Dispose of Vegetation Off Unit

This alternative involves the excavation and ex situ grouting of the OFASB and effluent
ditchline. The OFASB would be excavated to a maximum depth of 2 feet. The excavated soils
would be mixed with the solidification/stabilization reagents at predetermined ratios, and the
soils would be placed back into the basin. When all of the OFASB soils are treated, the process
would be repeated an effluent ditchline soils. Upon completion of ex situ grouting, the treated
soils would be placed in the OFASB, the OFASB would be backfilled and compacted to grade, and an
engineered cap as described in alternative S2 would then be constructed over the OFASB to
minimize surface infiltration and reduce the potential for contaminant migration. These
alternatives (S4A/S4B) would reduce the risks associated with direct radiation exposure and
minimize, through grouting the most contaminated soils, future potential migration of
contaminants to the groundwater but since the significantly contaminated soils would reguire
excavation prior to treatment exposure to remediation workers could occur.

Alternative S4A includes the removal and chipping of the vegetation followed by incineration at
the SRS GIF. Existing SRS institutional controls would remain in effect. Following remediation
the unit would be maintained for a present value cost of $2,300,000.

Alternative S4B includes the removal of the vegetation followed by transport and disposal at the
SRS Burial Grounds which have trenches that are permitted to accept debris. Existing SRS
institutional controls would remain in effect. Following remediation, the unit would be
maintained for a present value cost of $1,900,000.

Alternative S5 - Dispose of 2 Feet of Soils at Envirocare, Incinerate Vegetation at GIF, and Cap

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This alternative involves the excavation and off-site disposal of the top 2 feet of the OFASB
(4,500 cubic yards) and effluent ditchline soils (167 cubic yards). A backhoe would be used to
excavate the OFASB soils. The backhoe would start at one end of the ditchline and basin and
would gradually progress along the edges and toward the middle of the ditchline and basin until
all of the soil within 2 feet is removed. Excavated soil would then be placed directly onto
lined trucks for transport from the waste unit. From the OFASB, the excavated soils would
either be transported directly to the Envirocare facility in Clive, Utah, or transferred to a
railcar for final transport to the Envirocare facility. Upon completion of the excavation, and
off-site disposal activities, the OFASB would be backfilled and compacted to grade, and an
engineered cap as described in alternative S2 would then be constructed over the OFASB to
minimize surface infiltration and reduce the potential for contaminant migration. This
alternative would reduce the risks associated with direct radiation exposure and minimum through
off unit disposal, future potential migration of contaminants to the groundwater but since the
significantly contaminated soils would reguire excavation prior to disposal, exposure to
remediation workers could occur. Also, since transportation would be reguired off the SRS, the
potential for exposure to the public exists.

This alternative also includes the removal of the vegetation followed by incineration at the
SRS GIF. Existing SRS institutional controls would remain in effect. A present value cost of
$9,000,000 is estimated for this alternative.

VII.B Description of the Considered Alternatives for the OFASB Operable Unit Groundwater

Four alternatives were evaluated for remedial action of the OFASB operable unit groundwater.
Each alternative is described below.

Alternative GW1 - No Action

This alternative is the same as the no action described in alternative SI. Because no action
would be taken and the OFASB would remain in its present condition there would be no reduction
of risk. The present value estimate to perform both the no action for soils/vegetation and
groundwater would be $280,000 due to performance of five year reviews since waste is left in
place.

Alternative GW2A - Groundwater Extraction, Treatment with Reverse Osmosis and Ion Exchange,
Disposal of Residuals, and Reinjection

This alternative consists of setting up a system of 11 extraction wells on 100 foot nodes to
hydraulically contain the contaminated water table aguifer plume. The groundwater would be
extracted from the ground and sent to a reverse osmosis unit which would separate the stream
into a concentrated retentate stream (the part of the groundwater feed stream that is retained)
containing the radionuclides and metal and a permeate stream (the part of the groundwater feed
stream that passes through the membrane) which contains treated water. The permeate stream
would next pass through an ion exchange unit designed to remove nitrate from the water. The
treated water from the ion exchange unit would then be piped to a system of injection wells
located up gradient from the extraction wells.

The treated water, which still contains tritium, would then be reinjected into the water table
aguifer to allow additional time for natural decay to reduce the level of tritium in the
groundwater. The retentate from the reverse osmosis unit and the regenerated liguid from the
ion exchange unit would then be collected and disposed.

Three methods for disposal have been found to be acceptable. All three involve solidifying the
waste in a cement-based matrix for final disposition. The Saltstone facility would provide the

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lowest cost method for treating the waste stream, however, this facility is designed to accept
waste from the ITP process only. If this facility can be modified, then the Saltstone facility
represents the preferred method for disposal of the concentrated liguid waste. If modifications
cannot be made, then the E-Area Vaults or the Envirocare facility can be used. This alternative
would reduce risks associated with exposure due to ingestion, of contaminated groundwater
through treatment.

Assuming use of the Saltstone facility and that the groundwater aguifer would be maintained, the
present value cost for this alternative is $17,800,000.

Alternative GW2B - Groundwater Extraction, Treatment with Reverse Osmosis, Disposal of
Residuals, and Reinjection

This alternative is nearly identical to the previous alternative (GW2A) except a dual ion
exchange system is used in place of the reverse osmosis and ion exchange system. In this
alternative, the ion exchange system would contain both an anionic and a cationic unit. For
this application, one unit is designed to remove the radionuclides and metals while the other is
designed to remove nitrate. The regeneration of one unit is normally done using an acid wash
while the other uses a basic wash. An added advantage of this system is that the two waste
streams can be used to neutralize each other before the waste is shipped for disposal. This
alternative would reduce risks associated with exposure due to ingestion of groundwater through
treatment.

Assuming use of the Saltstone facility and the groundwater aguifer would be maintained the
present value cost for this alternative is $13,200,000.

Alternative GW3 - Groundwater Controls Using Alternate Concentration Limits/Mixing Zone

This alternative will involve the installation of a monitoring well network between the basin
and the down gradient stream and initiation of periodic monitoring. The application for a
groundwater mixing zone has been approved by the appropriate regulatory agencies. This approval
is based on data from monitoring wells around the OFASB and groundwater modeling. This
alternative will demonstrate that remedial goal objectives will be met and MCLs will not be
exceeded beyond the groundwater mixing zone. Implementation of this alternative involves
installation and monitoring of groundwater wells as described in the groundwater mixing zone
application.

This alternative will reduce the risks associated with groundwater ingestion by ensuring that
through natural groundwater mixing zone processes the nearest groundwater receptor is not
exposed to groundwater contaminated above MCLs. Access controls are in place through
establishment of institutional controls to prevent exposure to the groundwater plume.

Since five year reviews of the remedy are reguired, the estimated present value for these
reviews, installation of monitoring wells, and monitoring is $1,300,000.

VIII. Summary of Comparative Analysis of the Alternatives

Description of Nine Evaluation Criteria

Each of the remedial alternatives was evaluated using the nine criteria established by the
National Oil and Hazardous Substances Contingency Plan (NCP). The criteria were derived from
the statutory reguirements of CERCLA Section 121. The NCP [40 CFR °300.430 (e)(9)] sets forth
nine evaluation criteria that provide the basis for evaluating alternatives and selecting a
remedy. The criteria are:

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• overall protection of human health and the environment,
• compliance with ARARs,
• long-term effectiveness and permanence,
• reduction at toxicity, mobility, or volume through treatment,
• short-term effectiveness,
• implementability,
• cost,
• state acceptance, and
• community acceptance.

In selecting the preferred alternative, the above mentioned criteria were used to evaluate the
alternatives developed in the Corrective Measures Study/Feasibility Study for the Old F-Area
Seepage Basin (U) (WSRC, 1996a). Seven of the criteria are used to evaluate all the
alternatives, based on human health and environmental protection, cost, and feasibility issues.
The preferred alternative is further evaluated based on the final two criteria: state
acceptance and community acceptance. Brief descriptions of all nine criteria are given below.

Overall Protection of Human Health and the Environment - The remedial alternatives are assessed
to determine the degree to which each alternative eliminates, reduces, or controls threats to
human health and the environment through treatment engineering methods, or institutional
controls.

All the soil/vegetation alternatives (with the exception of the no action alternative) would
reduce the risks associated with direct radiation exposure, however, the in situ grouting, ex
situ grouting, and off unit disposal options would further minimize the potential migration of
contaminants to the groundwater. The groundwater alternatives (with the exception of the no
action alternative) would reduce the risks associated with groundwater ingestion.

Compliance with Applicable or Relevant and Appropriate Reguirements (ARARs) - ARARs are Federal
and state environmental regulations that establish standards which remedial actions must meet.
These are three types of ARARs: (1) chemical-specific, (2) location-specific, and (3)
action-specific.

Chemical-specific ARARs we usually health or risk-based levels or which, when applied to
unit-specific conditions, result in the establishment of numerical values. Often these
numerical values are promulgated in Federal or state regulations.

Location-specific ARARs are restrictions placed on the concentration of hazardous substances or
the conduct of activities solely because they are in specific locations. Some examples of
specific locations include floodplains, wetlands, historic places, and sensitive ecosystems or
habitats.

Action-specific ARARs are usually technology- or remedial activity-based reguirements or
limitations on actions taken with respect to hazardous substances or unit specific conditions.
The reguirements are triggered by the particular remedial activities that are selected to
accomplish a remedy.

The remedial activities are assessed to determine whether they attain ARARs or provide grounds
for invoking one of the five waivers for ARARs. These waivers are:

• the remedial action is an interim measure and will become a part of a total remedial
action that will attain the ARAR,
• compliance will result in greater risk to human health and the environment than other
alternatives,

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       •    compliance is technically impracticable from an engineering perspective,
       •    the alternative remedial action will attain an equivalent standard of performance
            through use of another method or approach,
       •    the state has not consistently applied the promulgated requirement in similar
            circumstances or at other remedial action in the state.

In addition to ARARs, compliance with other criteria, guidance, and proposed standards that are
not legally binding, but may provide useful information or recommended procedures should be
reviewed as To-Be-Considered when setting remedial objectives.

All the alternatives  (with the exception of the no action alternative) for both soil/vegetation
and groundwater will comply with ARARs.  The mixing zone alternative will achieve MCLs at the
compliance point as established in the approved groundwater mixing zone application.  Aquifer
restoration will occur through natural groundwater mixing processes in approximately 200 years
based on modeling conducted in the approved groundwater mixing zone application.

Long-Term Effectiveness and Permanence - The remedial alternatives are assessed based on their
ability to maintain reliable protection of human health and the environment after
implementation.

The grouting  (in situ and ex situ) and off unit disposal alternatives provide more effectiveness
than the capping alternative since the waste is solidified below grade or removed from the unit.
The off unit disposal alternative provides the most effectiveness through removal of the source
and disposal at an off unit location.  The pump and treat groundwater alternatives would
permanently remove most contaminants but would not improve the groundwater risks associated with
tritium over the groundwater mixing zone alternative.

Reduction of Toxicity, Mobility, or Volume Through Treatment - The remedial alternatives are
assessed based on the degree to which they employ treatment that reduces toxicity (the harmful
nature of the contaminants),  mobility  (ability of the contaminants to move through the
environment), or volume of contaminants associated with the unit.

The in situ and ex situ grouting alternatives for the soil would reduce contaminant mobility
through treatment.  The pump and treat alternatives for the groundwater would reduce the volume
of contaminated groundwater through treatment.

Short-Term Effectiveness - The remedial alternatives are assessed considering factors relevant
to implementation of the remedial action, including risks to the community during
implementation, impacts on workers, potential environmental impacts (e.g., air emissions), and
the time until protection is achieved.

In situ grouting and capping for the soil would provide the least potential for exposure to the
worker while off unit disposal would pose the highest potential for exposure to the public since
waste would be transported outside of the SRS.  Groundwater pump and treat alternatives will
provide the highest potential for exposure to workers through future disposal needs of the
treatment medium  (reverse osmosis, ion exchange).

Implementability - The remedial alternatives are assessed by considering the difficulty of
implementing the alternative including technical feasibility, constructability, reliability
of technology, ease of undertaking additional remedial actions (if required), monitoring
considerations, administrative feasibility (regulatory requirements),  and availability of
services and materials.

All alternatives are easily and readily available for application at the OFASB.  Separate

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regulatory acceptance of the groundwater mixing zone alternative is reguired prior to its
initiation.

Cost - The evaluation of remedial alternatives must include capital and operational, and
maintenance costs.  Present value costs are estimated within +50/-30 percent per EPA guidance.
The cost estimates given with each alternative are prepared from information available at the
time of the estimate.  The final costs of the project will depend on actual labor and material
costs, actual site conditions, productivity, competitive market conditions, find project scope,
final project schedule, and other variable factors.  As a result, the final project costs may
vary from the estimates presented herein.

The most costly alternative for the soil is off unit disposal followed by the grouting (in situ
and ex situ)  and capping alternatives which have similar order of magnitude costs.  The pump and
treat alternatives for the groundwater are significantly (an order of magnitude) more costly
than the groundwater mixing zone alternative. The no action alternative reguires the least cost.

State - In accordance with the FFA, the State is reguired to comment/approve on the RFI/RI
Report, the Baseline Risk Assessment, the Corrective Measures Study/Feasibility Study, and the
Statement of Basis/Proposed Plan.

State acceptance of previous document as listed above has been obtained.  Also, State acceptance
of the groundwater mixing zone application was reguired.

Community Acceptance - The community acceptance of the preferred alternative is assessed by
giving the public an opportunity to comment an the remedy selection process.  A public comment
period was held and public comments concerning the, proposed remedy are addressed in the
Responsiveness Summary of the Record of Decision.

No comments through the formal public comment period or through scoping with the CAB that would
cause deviation from the selected remedy were provided.

Detailed Evaluation

The remedial action alternatives discussed in Sections VII.A and VII.B have been evaluated using
the nine criteria just described.  Tables 4 and 5 present a summary of the evaluation of the
soil/vegetation and groundwater remedial alternatives.

IX.    The Selected Remedy

Based on the risks identified in the Baseline Risk Assessment, the OFASB unit pose a Significant
risk to human health.  Significant carcinogenic risks to the potential future worker are driven
by exposure from direct radiation from the basin soils contaminated with cesium-137 to a depth
of 2 feet  (~4.500 cubic yards) and effluent ditchline soils to a depth of 2 feet  (~167 cubic
yards).  Groundwater monitoring data indicates that iodine-129, nitrate, strontium-90, and
tritium exceed MCLS and uranium exceeds proposed MCLs.  Although radium his been decreasing over
time, it has exceeded MCLS and therefore, radium will be monitored.

The preferred alternative for the OFASB pipeline and pipeline soils is institutional controls.
This alternative will restrict this land to future industrial use and limit access to the soil
which might expose future workers to low concentrations of hazardous constituents through use of
administrative and access controls.

Based on risk characterization, risk evaluations, and a detailed analysis of retained
alternatives (Tables 4 and 5)  the preferred alternative for remediating the OFASB

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soils/vegetation is S3B: In Situ Grout Soils to 2 Feet & Dispose of Vegetation Off Unit which
will eliminate direct radiation risk and potential future impacts to the groundwater. The
preferred alternative for remediating the OFASB groundwater is GW3: Groundwater Controls Using
Alternate Concentration Limits/Mixing Zone which will monitor existing groundwater constituents
to assess impacts to potential receptors based on the approved groundwater mixing zone
application (demonstration). This mixing zone alternative will meet remedial action objectives.
MZCLs will be achieved throughout the groundwater aguifer and MCLs will be achieved at the
compliance point as described in the approved groundwater mixing zone application.

The OFASB is located in an area which has been recommended for industrial use by the CAB and so
designated by the U.S. DOE. Institutional controls at the OFASB Operable Unit will be
consistent with recommendations made in the "Savannah River Site Future Use Report Stakeholder
Recommendations for SRS Land and Facilities", January 1996 which include the recommendation that
"residential uses of SRS land should be prohibited." Current and future institutional controls
which will include access controls (e.g. fencing, security, land use restrictions, etc.) will
ensure that these recommendations are maintained. Under this land use policy alternatives S3B
and GW3 (which include institutional controls) will be protective of human health and the
environment.

Due to the presence of buried waste material and planned groundwater monitoring controls,
institutional controls have been chosen to augment the preferred alternative for the OFASB
source control operable unit including the pipeline and pipeline soils. Implementation of
institutional controls will reguire both short- and long-term actions. For the short-term,
signs will be posted at te waste unit which indicate that this area was used for disposal of
waste material and contains buried waste. In addition, existing SRS access controls will be
used to maintain the use of this site for industrial use only. Additionally, administrative
controls such as site use and site clearance permits as well as access controls such as filling
or grouting of pipeline manholes to prevent potential worker exposure will be employed.

In the long-term, it the property is ever transferred to non-federal ownership, the U.S.
Government will create a deed for the new property owner which will contain information in
compliance with Section 120(h) of CERCLA. The deed shall include notification disclosing
former waste management and disposal activities as well as remedial actions taken on the site,
and any continuing groundwater monitoring commitments.

The deed notification would, in perpetuity, notify any potential purchaser that the property has
been used for the management and disposal of radioactive materials and hazardous substances.
The deed would also include deed restrictions precluding residential use of the property.
However, the need for these deed restrictions could be reevaluated at the time of transfer in
the event that contamination no longer poses an unacceptable risk under residential use.

In addition, if the property is ever transferred to non-federal ownership, a survey plat of the
area would be prepared, certified by a professional land surveyor, and recorded with the
appropriate county recording agency.

Along with the institutional controls identified above, implementation of the soils/vegetation
alternative (S3B) will involve the removal of contaminated vegetation and off unit disposal
followed by the removal of contaminated soils in the effluent ditchline and placement in the
basin, and in situ grouting the top 2 feet of contaminated soils in the basin (~4,500 cubic
yards) and effluent ditchline soils (~167 cubic yards). An engineered cap (low permeability)
would then be constructed over the basin area (Figure 3) to minimize surface infiltration and
reduce the potential for contaminant migration. In situ grouting will follow placement of the
ditchline soils (Figure 4). Grout application may involve soil mixing or tilling and mixing,
however; the actual application method and stabilization admixture to be used in remediation

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will be specified in the remedial design.

Along with the institutional controls identified above, implementation of the groundwater
alternative (GW3) will involve the placement of compliance boundary monitoring wells
between the basin and the down gradient stream and periodic monitoring of these compliance wells
against the MCLs. This alternative will meet remedial action objectives. MZCLs will be
achieved throughout the groundwater aguifer and MCLs will be achieved at the compliance point as
described in the approved groundwater mixing zone application. All monitoring, compliance, and
reporting reguirements to satisfy the groundwater mixing zone demonstration should be met in
accordance with Section 5 of the approved groundwater mixing application (WSRC-RP-97-39, Rev.
1) -

Costs (capital, O&M and total present worth) for the selected remedy for the soil/vegetation are

$1,300,000 (capital)
$ 500,000 (O&M)
$1,800,000 (total present worth)

and for the groundwater are

$ 200,000 (capital)
$1,100,000 (O&M)
$1,300,000 (total present worth).

Total present worth costs are estimated to be approximately $3,100,000 for both the
soil/vegetation and groundwater media.

This proposal is consistent with EPA guidance and is an effective use of risk management
principles.

X. Statutory Determinations

Based on the OFASB RCRA Facility Investigation/Remedial Investigation (RFI/RI) Report and the
Baseline Risk Assessment, the OFASB poses no significant risk to the environment but poses
significant risk to human health. Therefore, treatment and capping is necessary for the OFASB
soils (basin and ditchline), institutional controls are necessary for the OFASB pipeline and
pipeline soils, and monitoring of the existing groundwater constituents (based on the
groundwater mixing zone application) to assess impacts to potential receptors for OFASB
groundwater. The selected remedy is protective of human health and the environment, complies
with Federal and State reguirements that are legally applicable or relevant and appropriate to
the remedial action, and is cost-effective. The size and location of the waste unit and the
levels of the contaminants preclude a remedy in which contaminants could be excavated and
treated effectively.

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In situ grouting/capping and the groundwater mixing zone application provide for a significant
reduction in the risks associated with direct radiation potential future impacts to the
groundwater, and groundwater ingestion.  Throughout implementation the selected remedy all ARARs
will have been complied with through use of treatment technologies on the soils, removal and off
unit disposal of the vegetation, and application at the groundwater mixing zone.  Since the soil
is grouted below grade, long term weathering and the potential for leaching of contaminants is
minimized.  Worker and public safety is maximized through minimizing handling of contaminated
media.  This selected remedy provides the most cost effective:  option considering the OFASB is
located in an identified industrial zone.

This remedy utilizes permanent solutions and alternative treatment technologies and satisfies
the statutory preference for remedies that employ treatment (in situ grouting)  that reduces
toxicity, mobility, or volume as a principal element.

XI.     Explanation of Significant Changes

The Statement of Basis/Proposed Plan and the draft RCRA permit modification provided for
involvement with the community through a document review process and a public comment period.
Comments that were received during the 45-day public comment period are addressed in Appendix A
of this Record of Decision and are available with the final RCRA permit.

There were no significant changes to the selected remedy as a result of public comments.
Approval of the groundwater mixing zone application was accelerated in order to obtain approval
of the groundwater mixing zone application prior to approval of this Record of Decision.  This
groundwater mixing zone application demonstrates the appropriateness of aguifer restoration
during passive remedial action.

In selecting the remedy in this Record of Decision, a Savannah River Site bulk disposal
alternative was not evaluated in the feasibility study but is currently being developed and
evaluated for radiologically contaminated soil/debris as a soils consolidation facility (SCF).

Should the SCF concept become a Savannah River Site remedial option for radiologically
contaminated soils prior to implementation of the selected OFASB remedy, then the bulk disposal
SCF alternative will be evaluated for the OFASB.  This evaluation will fully consider the nine
criteria established by the NCP in determining if the SCF alternative is an appropriate remedy
for the OFASB and if the SCF remedy is determined appropriate for the OFASB, the change in
remedy will cause no significant loss of monetary resources.

Should use of the SCF concept be deemed appropriate at the OFASB, this Record of Decision would
reguire modification.

XII.   Responsiveness Summary

There were ten comments received during the public comment period.  The Responsiveness Summary
(see Appendix A) of this Record of Decision addresses these comments.

XIII.    Post-ROD Document Schedule

The post-ROD document schedule is listed below and is illustrated in Figure 5.

Soil/Groundwater

1.     Corrective Measure/Remedial Design Workplan (CM/RDW)  Revision 0 for the  OFASB will be
       submitted for EPA and SCDHEC review 86 calendar days after issuance of the ROD.

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2. EPA and SCDHEC review of the OFASB CM/RDW Revision 0 will last 45 calendar days.
3. SRS revision of the OFASB CM/RDW will be completed 30 calendar days after receipt of all
regulatory comments.
4. EPA and SCDHEC final review and approval of the OFASB CM/RDW Revision 1 will last 30
calendar days.
5. Remedial Design Report/Remedial Action Workplan (RDR/RAWP) Revision 0 for the OFASB will
be submitted 266 calendar days after issuance of the ROD.
6. EPA and SCDHEC review of the OFASB RDR/RDWP Revision 0 will last 90 calendar days.
7. SRS revision of the OFASB RDR/RAWP will be completed 60 calendar days after receipt of all
regulatory comments.
8. EPA and SCDHEC final review and approval of the OFASB RDR/RAWP Revision 1 will last 30
calendar days.
9. OFASB Remedial Action Start on the soils and groundwater will begin following EPA and
SCDHEC approval of the RDR/RAWP.
10. OFASB Post Construction Report (PCR) Revision 0 will be submitted to EPA and SCDHEC 83
calendar days after completion of the remedial action.
11. EPA and SCDHEC review of the OFASB PCR will last 90 calendar days.
12. SRS revision of the OFASB PCR will be completed 60 calendar days after receipt of all
regulatory comments.
13. EPA and SCDHEC final review and approval of the Revision 1 PCR will last 30 calendar days.

Vegetation

1. OFASB Vegetation Remedial Action Start will begin within 15 months after issuance of the
ROD.

All vegetation within the basin and ditch line area are considered impacted by contaminant.
Uptake and will be removed. Vegetation sampling and analysis will be performed to characterize
the vegetation as a waste to identify appropriate treatment options. Removal of contaminated
trees will include removal of roots and all trees will be treated off-unit. Vegetation removal
will be performed in a manner so as to minimize land disturbance and therefore the potential for
soil erosion. All land disturbances will be addressed in an approved soil erosion control plan
which will minimize to the extent possible, the potential for release of contaminated soil to
the surrounding areas.

Contaminated vegetation will be cut, sectioned, and packaged for transport at the waste unit.
Appropriate procedures will be used to ensure radiation exposure during all operations is as low
as reasonably achievable (ALARA). If necessary, wind breaks and radiological huts will be
employed to reduce the risk from wind blown contamination. In addition, site procedures do not
allow activity in contamination areas when wind velocity reaches 10 miles per hour. Handling of
trees and larger vegetation will be performed remotely, whenever possible, which may include the
use of cranes or other mechanical eguipment used in the logging industry.

Treatment of contaminated vegetation will not be implemented at the waste unit. It is
anticipated that contaminated vegetation will be disposed at an off unit facility. Off site
shipment and treatment of contaminated vegetation will comply with the "offsite rule" under
CERCLA. After completion of the final remedial action, including remediation of the basin
soils, a Post Construction Report will be submitted which will include the volume and
disposition of all vegetation removed from the unit.

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XIV. References
DOE (U.S. Department of Energy), 1994. Public Involvement, A Plan for Savannah
River Site. Savannah River Operations Office, Aiken South Carolina.

FFA, 1993. Federal Facility Agreement for the Savannah River Site, Administrative
Docket No. 89-05-FF, (Effective Date: August 16, 1993).

WSRC, (Westinghouse Savannah River Company) 1995a. Baseline Risk Assessment for the Old
F-Area Seepage Basin (U). WSRC-RP-94-1174. Rev. 1, Westinghouse Savannah River Company,
Aiken, South Carolina (1995a).

WSRC, 1995b. Data Summary Report for the Old F-Area Seepage Basin (U). WSRC-RP-94-943,
Rev. 0, Westinghouse Savannah River Company, Aiken, South Carolina (1995b).

WSRC, 1995c. RFI/RI Report for the Old F-Area Seepage Basin (U). WSRC-RP-94-942, Rev. 1.
Westinghouse Savannah River Company, Aiken, South Carolina (1995c).

WSRC, 1996a. Corrective Measures Study/Feasibility Study for the Old F-Area
Seepage Basin (U). WSRC-RP-95-385, Rev. 1, Westinghouse Savannah River Company, Aiken
South Carolina (1996).

WSRC, 1996b. Statement of Basis/Proposed Plan for the Old F-Area Seepage Basin
(904-49G) (U), WSRC-RP-95-1557, Rev. 1, Westinghouse Savannah River Company, Aiken,
South Carolina
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APPENDIX A

RESPONSIVENESS SUMMARY

The 45-day public comment period for the Statement of Basis/Proposed Plan for Old F-Area Seepage
Basin (904-49G) began on September 17, 1996 and ended on October 31, 1996. A public meeting was
held on October 15, 1996. Specific comments and responses are found below. The comments are
italicized and the responses are bolded.

Public Comments
Comment 1:
Scenario for Current Land Use-Direct Radiation
Response 1:
It appears that the occupancy factor for the visitor is too high. The Exposure
Freguency (events/year) and Exposure Duration (years) are probably unrealistically
conservative. If realistic values were used then the risk value would probably be
less than l.OE-06. In that event, this scenario would drop from the list of
significant risks. The other part of the eguation that drives the risk value
upward is the use of the highest detectable value (Tables 3-11 through 3-20) in
the calculation of risk. Again this unrealistically conservative, driving the
conclusion toward taking action when none may be warranted.

We believe the occupancy factor for the current on-unit visitor, which is defined
as an SRS researcher/sampler, is reasonable. The researcher/sampler is only
exposed for 6 days per year for 5 years, which is a reasonable estimate for an
SREL worker or ER sampler performing environmental studies at the OFASB. The EPA
standard default worker occupancy factors are 250 days per year for 25 years.
Comment 2:
The "use of the highest detectable value in the calculation of risk" is done
according to EPA and SCDHEC guidance. The regulatory guidance is that we
calculate a 95% Upper Confidence Limit (95% UCL) on the average detected value and
compare the 95% UCL or the maximum detected value, whichever is lower. The lower
of the two values is selected as the "Reasonable Maximum Exposure" concentration.
The 95% UCL can actually exceed the maximum detected value if there is a small
sample size, or if there is great variation in detected values, which will result
in using the maximum detect since it is the lower value.

Future Land Use-Noncarcinogenic Hazards

In the general use of the highest detectable value in calculating the risk is not
justified; a more realistic risk should be calculated.
The ingestion of groundwater (adult and child) scenarios list several
nonradioactive inorganic analyzes that derive the Hazard index above unity. These
include manganese, arsenic, lead, and nitrate. The Plan describes that inorganic
analytes are compared to their appropriate background levels and are to be
eliminated if their maximum detected concentration onsite is less than twice their
mean background concentration. The comparison of the maximum detected
concentration to the mean detected concentration is like comparing apples and
oranges. The comparison should be of the mean detected concentration to the mean
background concentration to avoid incorrectly identifying an analyte with high
variability in the environment as being of concern. If the range of background
samples were compared to the range of basin samples, one could find that the
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maximum background sample would be in excess of the basin sample.

The identification of manganese as a chemical of concern is not supported by the
record of discharges to the basin. Arsenic is identified elsewhere as a legacy of
the farming activities in the area (components of arsenic were used as
pesticides). If these were detected from the risk analysis, then the only child
pathway for Aguifer Unit IIB remains above a HI of 1.0.

Given that residential use of this land is not recommended by the Citizens
Advisory Board, then this pathway does not constitute a risk worth remediating. A
similar justification is applicable to the "ingestion of basin soil and homegrown
vegetable (mercury)" pathways.

Response 2: The maximum detected value becomes the Reasonable Maximum Exposure(RME) point
concentration if it is lower than the 95UCL (see response #1 above). Use of the
current data screening protocol could possibly eliminate naturally-occurring
inorganic constituents, such as manganese, arsenic, and lead. Nitrates are
related to SRS processes and would not be eliminated.

The second point about ingestion of groundwater using maximum detected values to
derive an HI above unity and the use of 2X background comparison was covered in
the response to comment #1 above. Current regulatory guidance prescribes the use
of background comparisons.

As stated above (response #1), manganese and arsenic are likely to be naturally-
occurring, but they passed through the Contaminant Of Potential Concern (COPC
screening process as applied in 1994 when this Baseline Risk Assessment (BRA) was
prepared. The new RCRA Facility Investigation/Remedial Investigation (RFI/RI)/BRA
Scoping Process that is now being developed will all for use of an uncertainty
analysis to consider natural abundance, anthropogenic sources, and likely future
land uses in considering the application of any COPC in the risk assessment
process.

The use of the RFI/RI/BRA Scoping Process would allow SRS to potentially screen
out future residential land use in areas that are designated for future industrial
or nuclear industrial uses. However, for this waste unit, use of this screening
protocol would not change the conclusion on the appropriate remedy.

Comment 3: Future Use Scenarios-Ingestion of Groundwater-Radioactivity/Beryllium

The ingestion of groundwater by future residents lists potassium-40 as the major
contributor of risk (82% of the total risk). Potassium-40 occurs naturally and is
not a contaminant added by the operations of the Savannah River Site. The
screening criteria for potassium-40 must be flawed (too low). Potassium should
not appear in any of the risk calculations. Additionally, lead-212 and radium-226
occur naturally; however, they may also be contributed from SRS activities.
Comparison to a valid set of background samples and use of appropriate comparison
values (not maximum sample concentration to average background concentration)
should reveal whether their presence is due to SRS activities. Strontium-90 could
be present due to either fallout or SRS activities.

However, given that residential use is not recommended the risk does not justify
cleanup actions.
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The presence of beryllium in the on-unit worker scenario is puzzling. To my
knowledge beryllium was not a component of the materials discharged to the basin.

Response 3: The K-40, which is naturally-occurring, could possibly be eliminated using the
current COPC screening process or the RFI/RI/BRA Scoping Process that is being
developed. See background comparison responses above (response #1 and #2).
Beryllium is a naturally-occurring metal that occasionally shows up at SRS waste
units. However, for this waste unit, use of this screening protocol would not
change the conclusion on the appropriate remedy.

Comment 4: Future Use Scenario-Inhalation of Soil-Radioactivity

Worker occupancy factors are probably too high, residential use is not recommended
by the CAB, risk could be eliminated with a covering (2 feet of clean soil).

Response 4: The Future Industrial Worker scenario is the standard default exposure scenario.
The 250 days per year exposure over 25 years is a suggested default assumption in
EPA guidance. SRS, EPA, and SCDHEC agreed to use the standard worker scenario in
all SRS Baseline Risk Assessments. Other worker exposures, such as the
researcher/scenario, are also evaluated in BRAs. The result of the inhalation of
soil (radioactivity) pathway results actually helps the risk manager decide that
an action to limit that exposure is warranted, such as the application of a 2 ft.
layer of clean soil over the closed basin. Although the residential scenario was
not selected as the preferred land use, additional action (grouting and a low
permeability cap) is reguired to protect the groundwater aguifer from future
impacts from the radiologically contaminated soils present at this waste unit.

Comment 5: Future Use Scenario-Ingestion of Soil/Vegetables-Radioactivity

A covering of clean soil would eliminate the worker pathway, residential use is
not recommended by the CAB.

Response 5: Shielding through use of 2 to 3 feet of soil is effective in eliminating the
direct radiation exposure hazards associated with the worker. Although the
residential scenario was not selected as the preferred land use, additional action
(grouting and a low permeability cap) is reguired to protect the groundwater
aguifer from future impacts from the radiologically contaminated soils present at
this waste unit.
Comment 6:
Recommendation
The most cost-effective approach would be to excavate the ditchline soils to a
depth of 2 feet and place the soil in the basin; remove the vegetation growing in
the ditch and basin, chip and place in the basin; place clean soil in the ditch
and basin; then grade to minimize erosion, apply topsoil and plant ground cover to
control erosion.
Response 6: Grouting of the top layer of contaminated soils at this waste unit eliminates the
need for a more protective cap (i.e. with grouting a cap with only a 10E-5 cm/sec
hydraulic conductivity is reguired to protect the groundwater verses the
reguirement of a 10E-6 cm/sec hydraulic conductivity cap without grouting).
Grouting is also more permanent since the solidified soil would not be exposed to
weathering and reguires no long-term maintenance. Also, with the use of a 10E-5
cm/sec cap, maintenance is easier and less costly (primarily due to the
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availability of 10E-5 cm/sec soil at SRS).

Capping the vegetation was evaluated in the Corrective Measures Study/Feasibility
Study for this waste unit. Since grouting is the primary treatment only a 10E-5
cm/sec cap is needed. Also, extra handling and storage of the vegetation would be
reguired while the grouting process is being conducted causing increased costs and
environmental management concerns. The grouting process is expected to take
several months to complete.

Ditchline soils are planned to be moved into the basin and clean soil in the ditch
and basin are planned to return the ditch to natural grade and to provide
shielding to workers in the basin. The cap will be constructed to promote surface
water runoff and a vegetative cover will be prepared to provided added
evapotranspiration benefits in minimizing infiltration of surface water into the
basin area.

Public Meeting Comments

The following comments were taken from the October 15, 1996 OFASB Public Meeting transcript.

Comment 7: Why isn't the proposed soils consolidation facility being considered to
permanently take care of the situation with the limited depth of contamination
since with the soils consolidation facility would not have to permanently take
care of the waste unit or maintain the cap or soil cover after excavation and
transportation to the soils consolidation facility? (paraphrased from the public
meeting transcript during the presentation of the proposed remedy for this waste
unit)

Response 7: This waste unit consists of soil contamination to a depth of about 26 feet below
the basin bottom. Therefore, there is a significant guantity of soil that may
reguire excavation and transport to the pre-conceptual soil consolidation facility
(~58,000 cubic yards in place volume).

The Corrective Measures Study/Feasibility Study considered a number and range of
alternatives for remediation of the source unit. However, the soil consolidation
facility has been considered for this waste unit in the Proposed Plan but without
a site, design, or available capacity at the present time or short term is not
considered feasible at this time. (The use of a soils consolidation facility
would not necessarily provide additional protectiveness to human health or the
environment.) The selected remedy identified in this ROD meets the reguirements
under CERCLA and the NCP. Therefore, it was determined that if this soil
consolidation facility comes on line and that the soils from this waste unit are
acceptable to this soil consolidation facility, then; the action at this waste
unit may be reevaluated to consider the soil consolidation facility.

Comment 8: What kind of risk modeling and prioritization based on the associated risks have
been studied and reviewed for this waste unit? (paraphrased from the public
meeting transcript during the presentation of the proposed remedy for this waste
unit)
Response 8: The groundwater at this waste unit has been contaminated from the basin
operations. Modeling was performed to determine if current contaminant
concentrations in the basin and ditchline soils serve as a continuing source to
groundwater contamination above primary environmental standards. This modeling
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identified that contaminant concentration in the top two feet of the basin and
ditchline soils could cause future impacts to the groundwater aquifer This is the
primary basis for treating this soil layer using stabilization/solidification
techniques.

Comment 9: The risk has been identified as a risk to the workers that are going to be working
in the vicinity of that area (the waste unit). Just how significant is the risk
in terms of radiation exposure to the workers that are close to those areas? And
how do you compare that risk which is probably quite small, to the risk that will
be essentially taken by the workers that will go in to do the remediation of this
site? Heavy equipment disturbing contaminated soil, getting radiation exposure,
those activities, how do you balance the two to say it would probably be better to
just push clean dirt over the top of it and not disturb the soil, not to do
anything that does that? Because apparently it's not a risk to the public sector,
it's only a risk to the worker, as opposed to actually going in and actively doing
things to disturb the soil, to do the grouting in place, and those type of
activities; how does the other side of the equation get weighed in when you make a
decision that this is an area that we need to go and remediate? (from the public
meeting transcript during the formal comment period for this waste unit)

Response 9: Existing institutional controls in the area of this waste unit prevent access and
therefore radiation exposure to workers in the vicinity of this waste unit. No
risks are identified for the current worker based on a visitor/sampler scenario
(see response 1). The future industrial worker risks are significant based on the
EPA standard default scenario (see response 4). These risks along with the risks
to the remediation worker are evaluated qualitatively in the detailed analysis of
alternatives, specifically the short term effectiveness criteria. It is this
evaluation that drives the preference of in situ treatment technologies over ex
situ treatment technologies.

The selected remedy identifies a minimal amount of movement of contaminated soil
(~167 cubic yards from the ditchline to be placed in the basin). Following
placement of the ditchline soils in the bottom of the basis a layer of clean soil
will be placed over the contaminated soil to provide shielding from radioactive
contaminants. After the clean soil is placed (~3 feet) the top 2 foot layer of
contaminated basin soil and the ditchline soil will be grouted followed by
backfilling the basin to grade and placement of a low permeability cap over the
basin area.
Comment 10: Mike Rourak: My name is Mike Rourak and my question is directed directly to Mr.
Brian Hennessey's earlier discussion [unintelligible] Silverton Road property for
example. In the Future Use Manual that was sent out to some of us about the
disposal of close to a million acres of property for DOE, in your deed
restrictions there're things that we cannot do. And we're going to need a little
bit before we can respond back to Washington. Those of us who received the
manual, we almost are going to need to know what those deed restrictions are
because if we cannot have a subdivision then there's no need to bid the price
accordingly or say that's what we want to use it for. If we cannot graze cattle
there like we do in Tennessee at [unintelligible] or something or grow crops
because we cannot put a well in for contamination, then we are left with only
looking at for the pine trees.

So being federal, you own this property. Even with deed restrictions you've got
to give us either a Phase I, II or III audit. In this case, it's the seller who
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has to provide this liability, not necessarily. The buyer's neglect of liability
to due diligence. So it would really help if we knew what deed restrictions would
be there to a more extent and also what we can use the land for. If I want to use
it for applying 50 - - under the Code of Federal Regulations 503, if I want to use
it for bio solid disposal, can I do so? Because it's adjacent to your other
property. So the deed restrictions that you brought up were of immense concern
about responding back to the future use and the disposal of roughly 849,000 acres
nationwide for - to be put back into - I understand from Washington, they would
like to put it back mainly into public use to get the taxes off of it. Maybe not
so much for the government but for the local entities who lose the tax base.
Thank you. (from the public meeting transcript)

Response 10: The SRS Future Use Project Report was distributed to inform citizens of the
planned future uses of SRS. The recommendations that were presented in the
report may change over time and will be discussed with the stakeholders. Deed
restrictions for federal property are not determined until the land is transferred
to non-federal control. At the time of property transfer, the need for deed
restrictions will be evaluated. Due to natural attenuation, decay, etc., the
conditions at specific areas may not warrant any deed restrictions. All legal
reguirements will be met at the time of property transfer.

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