PB98-964029
EPA541-R98-190
May 1999
EPA Superfund
Record of Decision:
Savannah River Site (USDOE)
F-Area Retention Basin (281-3F)
Aiken, SC
9/4/1998
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Department of Energy
Savannah River Operations Office
P.O. Box A
Aiken, South Carolina 29802
APR 28 1999
Mr. K. A. Collinsworth, Manager
Federal Facility Agreement Section
Division of Site Assessment and Remediation
Bureau of Land and Waste Management
South Carolina Department of Health and Environmental Control
2600 Bull Street
Columbia, SC 29201
Mr. J. L. Crane, Manager
SRS Remedial Project
Waste Management Division
United States Environmental Protection Agency, Region IV
61 Forsyth Street, SW
Atlanta, GA 30303
Dear Mr. Collinsworth and Mr. Crane:
SUBJECT: Submittal of the Record Copy of the Signed Record of Decision for the F-Area
Retention Basin (281-3F)
Enclosed, please find a signed copy of the F-Area Retention Basin Record of Decision
for your records. Savannah River Site (SRS) will make the distribution of the
Administrative Record file(s) and publish the notice of availability.
Please contact me at (803) 725-7032 if you have any questions.
Bnan T. Hennessey
Environmental Restoration Division
SRS Remedial Project Manager
BTH/LHW:ed
OD-99-254
Enclosure
1. Record of Decision for the F-Area Retention Basin (281-3F), WSRC-RP-97-145,
Revision. 1.1
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A. B. Gould, DOE-ECD, 703-A
C. V. Anderson, DOE-ERD, 703-A
S. A. Holt, Dynamac*
C. B. Warren, US EPA-IV
K. B. Feely, US EPA-IV
J. K. Lindler, SCDHEC-Columbia
J. T. Litton, SCDHEC-Columbia
M. D. Sherritt, SCDHEC-Columbia
G. K. Taylor, SCDHEC-Columbia
SRS Administrative Record Files (Palmer, 730-2B, 1000)*
*w/enclosure
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SEP *4
^^^^^ ^^^^^^^w^^^^^o'T^
United States Department of Energy ASSESSMENT* ^
Savannah River Site
Record of Decision
Remedial Alternative Selection for the
F-Area Retention Basin (281-3F) (U)
WSRC-RP-97-145
Revision 1.1
August 1998
Prepared by:
Westinghouse Savannah River Company .
Savannah River Site /
Aiken, SC 29808
Prepared for U.S. Department of Energy under Contract No. DE-AC09-9 SAV»NN»M *.*<*
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Record of Decision for the F-Area Retention Basin (281-3F) WSRC-RP-97-145
Savannah River Site Revision 1.1
August 1998
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Record of Decision for the F-Area Retention Basin (281-3F) WSRC-RP-97-145
Savannah River Site Revision 1.1
August 1998 ^^^^^
DISCLAIMER
This report was prepared by Westinghouse Savannah River Company (WSRC) 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 service 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 for the F-Area Retention Basin (281-3F) WSRC-RP-97-145
Savannah River Site Revision 1.1
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RECORD OF DECISION
REMEDIAL ALTERNATIVE SELECTION (U)
F-Area Retention Basin (281-3F)
WSRC-RP-97-145
Revision 1.1
August 1998
Savannah River Site
Aiken, Soutb 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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Record of Decision for the F-Area Retention Basin (281-3F) WSRC-RP-97-145
Savannab River Site Revision 1.1
August 1998
DECLARATION7 FOR THE RECORD OF DECISION
Unit Name and Location
F-Area Retention Basin (SRS Building 281-3F)
Savannah River Site
Aiken, South Carolina
The F-Area Retention Basin (FRB) Operable Unit (OU) is listed as a Resource Conservation and
Recovery Act (RCRA) 3004 (U) Solid Waste Management Unit/Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA) Unit in Appendix C of the Federal
Facility Agreement (FFA) for the Savannah River Site (SRS). This OU includes the retention
basin (basin soils), the former process sewer line (pipeline, pipeline sediment, and pipeline
associated soils), and the groundwater associated with the unit.
Statement of Basis and Purpose
This decision document presents the selected remedial alternatives for the FRB OU located at the
SRS south of Aiken, South Carolina. The selected alternatives were developed in accordance
with CERCLA, as amended by SARA, RCRA, 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 (ROD), may present an
imminent and substantial endangerment to public health, welfare, or the environment.
Declaration - 1
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Record of Decision for the F-Area Retention Basin (281-3F) WSRC-RP-97-145
Savannah River Site Revision 1.1
August 1998
Description of the Selected Remedy
The preferred alternatives for the FRB OU are: (1) for the basin soil; Alternative S5:
Institutional Controls, Grouting, a Low Permeability Cover, and Groundwater Monitoring; (2)
for the former process sewer line: Alternative P4: Institutional Controls, Pipeline Grouting, and
Soil Excavation and Disposition with Basin Soils; and (3) for the groundwater; Alternative Gl:
No Action. The waste unit will be physically maintained and institutional controls will remain in
place in perpetuity. The field conditions will be evaluated to determine the need to modify the
program or to identify if further remedial action is appropriate during the five-year ROD review.
Under Alternative S5, deep basin soil will be grouted from approximately 0.6 m (2 ft) above the
basin bottom to approximately 4.3 m (14 ft) below grade. The purpose of grout is to prevent
leaching of Sr-90, which is the only contaminant migration COC (CMCOC) to the groundwater
above maximum concentration level 8.0 pCi/L. Furthermore, grouting the soil provides an
additional layer of protection by offsetting the inherent uncertainty associated with the
mathematical model used to predict contaminant migration. Grouting will also immobilize other
deep contaminants which represent principal threat source material such as Cs-137, Ra-226,
thallium, arsenic, etc., and further reduce infiltration of water through the deeper contaminated
soils. Grouting of soils is preferred over only capping because it meets the CERCLA preference
for treatment. A cover will be provided over the stabilized soil to minimize stormwater
percolation and erosion. The cover is also very effective in reducing direct radiation exposure
received from radionuclides in the shallow soil. This alternative includes institutional controls to
prevent exposure of current and future workers to hazardous constituents in the waste unit and
direct radiation from the waste unit. Since waste is left in place, the future use of land will be
restricted to industrial use to prevent unrestricted residential use of the land.
In situ grouting reduces air emissions and is relatively simple to implement. However, in situ
grouting results in a slight increase in waste volume. The volume of the basin, when clean soil is
excavated prior to grouting, will be adequate to accommodate any increase in grouted soil
volume. The estimated volume of grout/soil mixture is 6,600 mj (8,100 yd3).
Implementation of institutional controls will involve both short- and long-term actions. For the
short-term action, signs will be posted at the FRB OU indicating that this area was used for the
disposal of waste material and contains buried waste. Additionally, existing SRS access controls
will be used to maintain 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 take those actions
Declaration - 2
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Record of Decision for the F-Area Retention Basin (281 -3F) WSRC-RP-97-145
Savannah River Site Revision 1.1
August 1998
necessary pursuant to Section 120(h) of CERCLA. These actions will include a deed notification
disclosing former waste management and disposal activities as well as any remedial actions
taken on the site and any continuing groundwater monitoring commitments. These requirements
are also consistent with the intent of the RCRA deed notification required at final closure of the
RCRA facility if contamination would remain at the unit. 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 deed
restrictions may be reevaluated at the time of transfer in the event that contamination no longer
poses an unacceptable risk under residential use. Any revaluation of the need for deed
restrictions would be done through an amended ROD with the Environmental Protection Agency
(EPA) and the South Carolina Department of Health and Environmental Control (SCDHEC)
approval. In addition, a certified survey of the area will be prepared by a registered land
surveyor and will be included in the Post-Construction Report. The survey will be reviewed and
updated, as necessary, at the time the site is transferred and will be recorded into the appropriate
county recording agency. The FRB OU is located in Aiken County.
Per the EPA-Region IV Land Use Controls (LUCs) Policy, a Land Use Control Assurance Plan
(LUCAP) and a Land Use Control Implementation Plan (LUCIP) will be developed and
submitted to the regulators for their approval. The LUCAP will be submitted under separate
cover whereas the LUCIP will be submitted with the Remedial Work Plan/Remedial Design
Report/Remedial Action Work plan (RFWP/RDR/RAWP) for the FRB OU in accordance with
the Post-ROD document schedule provided in this ROD. The LUCAP will include the
information requested in the EPA policy. The LUCIP details how SRS will implement,
maintain, and monitor the land use control elements of the FRB OU ROD to insure that the
remedy remains protective of human health.
The LUC objective necessary to ensure the protectiveness of the preferred alternative is:
• Prevent unauthorized access/exposure to contaminated grout and basin soil
The institutional controls required to prevent unauthorized exposure to the contaminated grout
and soil include the following:
• Controlled access to the FRB waste unit through existing SRS security gates and
perimeter fences and the site use/site clearance programs
• Signs posted in the area to indicate that contaminated grout and soil are present in the
waste unit
Declaration - 3
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Record of Decision for the F-Area Retention Basin (281-3F) \VSRC-RP-97-l 45
Savannah River Site Revision 1.1
August 1998
• Notification of contaminated grout and soil to any future land owner through deed
notification as required under CERCLA Section 120(h)
Along with the institutional controls identified above for the FRB soils, the preferred alternative
for the process sewer line and associated soils will include pipeline and manholes grouting, and
excavation and disposition of pipeline soils (approximate volume 240m3 or 300 yd 3) with basin
soil. In this alternative, the localized areas of the contaminated soil around the pipeline hot spots
will be excavated. If necessary, the sections of pipeline associated with the hot spots will also be
excavated. The excavated soil and pipeline will be disposed of at the basin by in situ grouting
along with soil from the basin. Clean soil from SRS borrow areas will be used to fill excavated
areas around the pipeline. This alternative will also include access controls such as installing
warning signs around the pipeline area.
The preferred alternative for the FRB OU groundwater is "No Action". The history of the FRB,
the results of the groundwater modeling, and the current groundwater data reveal that the FRB-
associated groundwater poses no risk to human health or the environment. No contaminant
exceeds the maximum contaminant levels (MCLs) stipulated by EPA under the Safe Drinking
Water Act. However, to ensure that the grout monolith, formed by in situ grouting of soils under
Alternatives S5 and P4, has accomplished the required immobility of contamination, a
groundwater monitoring program will be established under Alternative S5. The groundwater
will be monitored semi-annually until it is confirmed that the remedial response action for the
FRB OU has achieved the required stabilization of the contaminants. Groundwater monitoring,
in conjunction with institutional controls, will help prevent ingestion of groundwater; verify that
no upgradient source of contamination exists; and reduce the uncertainty in the environmental
data collected during the characterization of the FRB OU.
The post-ROD document, the Corrective Measures Implementation/Remedial Design Work Plan
(CMI/RDWP), will be submitted to the U.S. Environmental Protection Agency (EPA) and the
South Carolina Department of Health and Environmental Control (SCDHEC) following the
issuance of the ROD. The CMI/RDWP will contain a summary description of the scope of work
for the remedial action design, detailed implementation/submittal schedule for subsequent post-
ROD documents, and an anticipated field activities start date. The CMI/RDWP will also include
regulatory review period, SRS revision period, and final regulatory approval period. The
regulatory review period, SRS revision period, and final regulatory review and approval period
normally are 45 days, 30 days, and 30 days, respectively.
Declaration - 4
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Record of Decision for the F-Area Retention Basin (281-3F) WSRC-RP-97-145
Savannah River Site Revision 1.1
August 1998
The SCDHEC has modified the SRS RCRA permit to incorporate the selected remedy.
Statutory Determinations
Based on the Remedial Investigation Report and the Baseline Risk Assessment (RI/BRA
prepared under SRS RFI/RI Program Plan), the FRB OU poses no significant risk to the
environment but poses a significant risk to human health. Therefore, institutional controls, in situ
grouting of the contaminated basin soil and covering the grouted soil with a low permeability
cover, and confirmatory groundwater monitoring are necessary for the basin soil; institutional
controls, pipeline and manhole grouting, and excavation and disposition of soil with the basin
soil are necessary for the pipeline and pipeline associated soil. No additional remedial action is
required for the FRB OU groundwater. However, as a part of remedial action, the groundwater
will be monitored: (1) to confirm that the source remediation has achieved the required
stabilization of the contaminants; (2) to relieve any uncertainty in the analytical data; and (3) to
verify that there exists no upgradient source contributing any contamination to the FRB OU
groundwater. If monitoring detects contamination above MCLs (or Risk-Based Concentrations
(RBCs) without MCLs) for those constituents attributable to the FRB OU groundwater (or an
upgradient source) for two consecutive monitoring periods, the regulators will be informed
within 30 days. A plan for evaluating the data and developing further action needed will be
submitted within 90 days for regulatory approval.
In situ grouting of soils and cover will: (1) result in the protection of unit groundwater through
the stabilization of unit constituents of concern (COCs); and (2) serve to stabilize the principal
threat source material. The grout testing under actual field conditions will be performed to
confirm the successful soil stabilization. The remedial action, therefore, will be protective of on-
unit human and ecological receptors by shielding exposure and preventing the assimilation of
unit COCs. The selected remedy is protective of human health and the environment, and
complies with Federal and state Applicable or Relevant and Appropriate Requirements
(ARARs). The selected remedy is cost-effective. This remedy utilizes permanent solutions and
alternative treatment technologies to the maximum extent practicable and satisfies the statutory
preference for remedies that employ treatments that reduce toxicity, mobility, or volume as a
principal element.
Declaration - 5
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Record of Decision for the F-Area Retention Basin (281-3F) WSRC-RP-97-145
Savannah River Site Revision 1.1
August 1998
Section 300.430 (f)(4)(>i) of the NCP requires 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-unit above health-based standards, the United States Department of
Energy, the United States Environmental Protection Agency, and the South Carolina Department
of Health and Environmental Control have determined that a Five-Year Review of the ROD for
the FRB OU will be performed to ensure continued protection of human health and the
environment.
Declaration - 6
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Record of Decision for the F-Area Retention Basin (281-3F)
Savannah River Site
August 1998
WSRC-RP-97-145
Revision 1-1
Date
S£P 0 4 1998
T. F. Heenan
Assistant Manager for Environmental Quality
U. S. Department of Energy
Savannah River Operations Office
Date
fD. Green
Division Director
Waste Management Division
U.S. Environmental Protection Agency
Date
R. Lewis Shaw
Deputy Commissioner
Environmental Quality Control
South Carolina Department of Health and Environmental
Control
Declaration - 7
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DECISION SUMMARY
REMEDIAL ALTERNATIVE SELECTION (U)
F-Area Retention Basin (281-3F)
WSRC-RP-97-145
Revision 1.1
August 1998
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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Savannah River Site Revision 1.1
August 1998 Pageiiofvi
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Savannah River Site Revision 1.1
August 1998 Pageiii of vi
DECISION SUMMARY
TABLE OF CONTENTS
SECTION PAGE
FIGURES iv
TABLES iv
ACRONYMS AND ABBREVIATIONS v
I. SAVANNAH RIVER SITE AND OPERABLE UNIT NAME, LOCATION, DESCRIPTION AND
PROCESS HISTORY. ... . . 1
II. SITE AND OPERABLE UNIT COMPLIANCE HISTORY 5
ID. HIGHLIGHTS OF COMMUNITY PARTICIPATION 8
IV. SCOPE AND ROLE OF THE OPERABLE UNIT WITHIN THE SITE STRATEGY 10
V. OPERABLE UNIT CHARACTERISTICS 14
VI. SUMMARY OF OPERABLE UNIT RISKS 21
VH. REMEDIAL ACTION OBJECTIVES AND DESCRIPTION OF THE CONSIDERED
ALTERNATIVES FOR THE FRB OPERABLE UNIT 36
VHI. SUMMARY OF COMPARATIVE ANALYSIS OF THE ALTERNATIVES 58
IX. THE SELECTED REMEDY 64
X. STATUTORY DETERMINATIONS 68
XI. EXPLANATION OF SIGNIFICANT CHANGES 69
XII. RESPONSIVENESS SUMMARY.-. ...... 70
XID. POST-ROD DOCUMENTS SCHEDULE AND DESCRIPTION 70
XIV. REFERENCES....... .. . 73
A i>piri\jT\Y^f A i
RESPONSIVENESS SUMMARY 1
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Savannah River Site
August 1998
WSRC-RP-97-145
Revision 1.1
Page iv of vi
FIGURES
Figure 1. Location of F Area at the Savannah River Site 2
Figure 2. Topographic Map of the F-Area Retention Basin and Surrounding Area 3
Figure 3. Plan View of the F-Area Retention Basin 4
Figure 4. RCRA/CERCLA Logic and Documentation 12
Figure 5. Revised Conceptual Site Model for the F-Area Retention Basin and Process Sewer
Line 15
Figure 6. Sampling Locations in and Around the F-Area Retention Basin 16
Figure 7. Distribution of Sr-90 by Depth - FRB Basin Area 30
Figure 8. Distribution of Sr-90 by Depth - FRB Basin Area 31
Figure 9. Distribution of Sr-90 by Depth - FRB Basin Area 32
Figure 10. Distribution of Cs-137 by Depth - FRB Basin Area 33
Figure 11. Distribution of Cs-137 by Depth - FRB Basin Area 34
Figure 12. Distribution of Cs-137 by Depth - FRB Basin Area 35
Figure 13. Low Permeability Cover Cross Section 43
Figure 14. Distribution of Sr-90 by Depth - Depicting the Zone of High Concentration -
FRB Basin Area Alternative S5 - Institutional Controls, Grouting, Low
Permeability Cover, and Groundwater Monitoring 47
Figure 15. Distribution of Cs-137 by Depth - Depicting the Zone of High Concentration -
FRB Basin Area Alternative S5 - Institutional Controls, Grouting, Low
Permeability Cover, and Groundwater Monitoring 48
Figure 16. Backhoe Soil Mixing 50
Figure 17. Jet and Soil Mixing Grouting Techniques 51
Figure 18. Locations of FRB Monitoring Wells and Upgradient Well 53
Figure 19. Location of Potential Trouble Spots 56
Figure 20. FRB Post-ROD Document Schedule 71
TABLES
Table 1. Unit-Specific Constituents Identified for the FRB Source Operable Unit 19
Table 2. Summary of Risk-Based COPCs, Grouped by Exposure Route 24
Table 3. Contaminants of Concern for Soil at the FRB Operable Unit with Maximum
Detected Concentrations and Remedial Goals 27
Table 4. Principal Threat Source Material Contamination at Depth for the FRB Operable
Unit with Their Maximum Detected Concentrations 29
TableS. Chemical-Specific Requirements 38
Table 6. Action-Specific Requirements 39
Table 7. Location-Specific Requirements 40
Table 8. Comparative Analysis Summary 60
Table 9. Selected Remedy Cost 66
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Savannah River Site
August 1998
WSRC-RP-97-145
Revision 1.1
Page v of vi
ACRONYMS AND ABBREVIATIONS
ANS American Nuclear Society
ARAR Applicable or Relevant and Appropriate Requirement
BRA Baseline Risk Assessment
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act
Ci Curies
COC Constituent of Concern
COPC Constituent of Potential Concern
CSM Conceptual Site Model
DOE United States Department of Energy
DQO Data Quality Objectives
EPA United States Environmental Protection Agency
ERD Environmental Restoration Department
FFA Federal Facility Agreement
FRB F-Area Retention Basin
CMS/FS Corrective Measures Study/Feasibility Study
ft foot (feet)
GPR Ground Penetrating Radar
HI Hazard Index
HQ Hazard Quotient
m meter
MCL Maximum Contaminant Level
pCi/g picoCurie per gram
NCP National Oil and Hazardous Substances Contingency Plan
NEPA National Environmental Policy Act
NPL CERCLA National Priorities List
OU Operable Unit
O&M Operation and Maintenance
PCR Post-Construction Report
mCi/g milHCurie per gram
RAO Remedial Action Objective
RAWP Remedial Action Work Plan
RBA Risk-Based Activity
RBC Risk-Based Concentration
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RCRA Resource Conservation and Recovery Act
RDR Remedial Design Report
RDWP Remedial Design Work Plan
RGO Remedial Goal Option
RJ CERCLA Remedial Investigation
RME Reasonable Maximum Exposure
ROD Record of Decision
SB/PP Statement of Basis/Proposed Plan
SCDHEC South Carolina Department of Health and Environmental Control
SCHWMR South Carolina Hazardous Waste Management Regulations
SRS Savannah River Site
TBC To-Be-Considered (requirement)
TCLP Toxicity Characteristic Leaching Procedure
USC Unit-Specific Constituent
WSRC Westinghouse Savannah River Company
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Savannah River Site Revision 1.1
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I. SAVANNAH RIVER SITE AND OPERABLE UNIT NAME, LOCATION,
DESCRIPTION AND PROCESS HISTORY
Savannah River Site Location, Description, and Process His ton
The Savannah River Site (SRS) occupies approximately 803 square kilometers (310 square
miles) of land adjacent to the Savannah River, principally in Aiken and Bamwell counties of
western South Carolina. SRS is a secured U.S. Government facility with no permanent residents
and is located approximately 40 kilometers (25 miles) southeast of Augusta, Georgia, and 32
kilometers (20 miles) south of Aiken, South Carolina (Figure 1).
SRS is owned by the United States Department of Energy (DOE); Management and operating
services are currently provided by Westinghouse Savannah River Company (WSRC). SRS has
historically produced tritium, plutonium, and other special nuclear materials for national defense
and the space program. Chemical and radioactive wastes are by-products of nuclear material
production processes.
Operable Unit Name, Location, Description, and Process History
The Federal Facility Agreement (WSRC, 1993) lists the F-Area Retention Basin (FRB) as a
Resource Conservation and Recovery Act/Comprehensive Environmental Response,
Compensation, and Liability Act (RCRA/CERCLA) unit requiring further evaluation using .an
investigation/assessment process that integrates and combines the RCRA Facility Investigation
(RFI) process with CERCLA Remedial Investigation (RI) to determine the actual or potential
impact to human health and the environment.
The FRB, designated as Building 281-3F, is located outside and south of the F-Area perimeter
fence, approximately 1035 m (3397 ft) from Fourmile Branch (Figure 2). The FRB, with an area
of approximately 0.6 acres (2,400 square meters) and approximate dimensions of 61 m (200 ft)
long, 36.6 m (120 ft) wide, and 2.1 m (6.9 ft) deep (Figure 3), was designed and operated as an
unlined, temporary container [capacity approximately 4.68 million liters (1.2 million gallons)]
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Revision 1.1
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Figure 1. Location of F Area at the Savannah River Site
SOUTH
CAROLINA
GEORGIA
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Savannah River Site
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WSRC-RP-97-145
Revision 1.1
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Figure 2. Topographic Map of the F-Area Retention Basin and Surrounding
Area
SCALE MFST
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7»
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69
n
n
a
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a
DO
u
Area Covered by vegetation
Areas within F-Area fence
** Stream
FET-4D Existing groundwater monitoring well
FRB-03
• Sample Location
o Manhole Location
Process Sewer
Ground surface elevation and contour
0 100 200 300 400 500
_:••—
Scale In feet
> %#
1 §
Sg 5.
»-> w n
VO EJ" .—
50
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a
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a'
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i
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O D
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Savannah River Site Revision 1.1
August 1998 PageS of 74
for potentially contaminated cooling water from the F-Area Canyon Facility and stormwater
drainage from the F-Area Tank Farm. Water was conveyed to the basin by a process sewer line
(approximately 168 m (550 ft) of 61-cm (24-inch) diameter and approximately 212m (700 ft) of
91 cm (36-inch) diameter that discharged into the north side of the basin. One branch of the line
conveyed water from the Canyon Facility and the other branch conveyed water from the Tank
Farm. Cooling water from the Canyon Facility generally had low levels of radioactivity, while
water from the Tank Farm is believed to have had only trace quantities of nonradionuclide
chemicals. The quantities of water released to the retention basin and the level of various
constituents contained within the water are unknown.
The FRB is currently an inactive basin filled with clean soil and covered with grass. The FRB
and its surrounding area lies at an elevation of approximately 275 ft above mean sea level.
Surface water runoff drains southeast to Fourmile Branch via an unnamed drainage ditch
(tributary) and overland flow.
II. SITE AND OPERABLE UNIT COMPLIANCE HISTORY
SRS Operational History
The primary mission of SRS was to produce tritium (3H), plutonium-239 (239Pu), and other
special nuclear materials for our nation's defense programs. Production of nuclear materials for
the defense programs was discontinued in 1988. SRS has provided nuclear materials for the
space program, as well as for medical, industrial, and research efforts up to the present.
Chemical and radioactive wastes are by-products of nuclear material production processes.
These wastes have been treated, stored, and in some cases, disposed at SRS. Past disposal
practices have resulted in soil and groundwater contamination.
SRS Compliance History
Waste materials handled at SRS are regulated and managed under 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 (SCDHEC). The
permit was most recently renewed on September 5, 1995. Part TV 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.
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On December 21, 1989, SRS was included on the National Priorities List (NPL). This inclusion
created a need to integrate the RFI Program established under RCRA with CERCLA
requirements to provide for a focused environmental program. In accordance with Section 120 of
CERCLA, DOE has negotiated an FFA (1993) with the United States Environmental Protection
Agency (EPA) and the South Carolina Department of Health and Environmental Control
(SCDHEC) to coordinate remedial activities at SRS with one comprehensive strategy that fulfills
these dual regulatory requirements.
Operable Unit History
The F-Area Retention Basin (FRB) includes the retention basin and the abandoned process sewer
line associated with the basin. The history of the FRB prior to characterization activities is
briefly described.
F-Area Retention Basin
The basin operated from 1955 until 1972 and was closed in December 1978. This closure
included the following activities:
• Sampling soil at four locations in the bottom of the retention basin
• Excavating approximately 0.6 m (2 ft) of soil from within the basin
• Sampling soil from 53 locations from the bottom excavation and basin berm
• Removing and transporting a total of 970 m3 (1267 yd3) of contaminated soil to Burial
Grounds (Building 643-G) for disposal
• Backfilling the basin with clean soil and seeding the area with grass
Excavation of soil from the bottom of the basin greatly reduced the level of radiological
contamination at the basin. The maximum levels of cesium-137 (Cs-137) and strontium-89/90
(Sr-89/90) detected in basin soils prior to excavation were 80,600 picoCuries per gram (pCi/g)
and 1540 pCi/g, respectively. The transferred radionuclide inventory was calculated as 11.5 Ci
of Cs-137 and 0.5 Ci of Sr-89/90. Following excavation, the maximum levels of Cs-137
detected in FRB soils were 430 pCi/g in the basin and 1410 pCi/g in the berm while the
maximum concentrations of Sr-89/90 were 1700 pCi/g in the basin and 1000 pCi/g in the berm.
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Process Sewer Line
A portion of the process sewer line extending north from the basin was aba idoned at the same
time the basin was closed. The branch of the line from the Tank Farm approximately 168 m (550
ft) of 61-cm (24-inch diameter) was sealed off at a point close to manhole P37 (see Figure 6).
The wastewater coming from the Tank Farm was diverted by installing a sluice box to Building
281-9F. The branch of the line from the Canyon Facility approximately 212m (700 ft) of 91-cm
(36-inch diameter) was sealed off at manhole P40 (see Figure 6). The abandoned portion of the
process sewer line north of the basin and outlet pipe located south of the basin (total length
approximately 380 m (1250 ft) is a part of this unit. The process sewer line north of manholes
P37 and P40 is still active and is not included in this unit.
The depth to the top of the abandoned process sewer line varies from less than 1 m (3ft) near the
original location of the basin to 4.6m (15 ft) for the segment from P40 to P39. There are several
access points to the abandoned process sewer line (see Figure 6). Two of the four access points
(P39 and one unnumbered manhole) are standard manholes constructed of brick. Access point
P38 is a nonstandard manhole constructed of poured concrete walls and floor. The final access
point is a valve/junction box located just downstream from manhole P39. The purpose of this
junction box was to regulate the amount of liquid released to the retention basin during normal
operation.
Drainage Ditch
The FRB was designed to discharge its contents through an outlet into a ditch naturally
connected with an unnamed tributary discharging into Fourmile Branch. However, the remedial
investigations.conducted.4B-jfe5pc«ae,tCuS,RS' established cleanup program revealed that the
outfall ditch and the unnamed tributary to Fourmile Branch were not impacted by FRB
operations; therefore, they are not considered for cleanup operations under this remedial action.
Operable Unit Compliance History
As previously stated, the FRB OU is listed in the FFA as a RCRA/CERCLA unit requiring
further evaluation to determine the actual or potential impact to human health and the
environment. A Remedial Investigation (RI) and Baseline Risk Assessment (BRA) were
conducted for the unit between 1995 and 1997. The results of the RJ and BRA were presented in
the RJ/BRA report (WSRC, 1997b). The RI/BRA report was submitted in accordance with the
FFA-approved implementation schedule and was approved by the EPA and SCDHEC in
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October 1997. The Corrective Measures Study/Feasibility Study (CMS/FS) (WSRC, 1997c) and
Statement of Basis/Proposed Plan (SB/PP) (WSRC, 1997d) were submitted in accordance with
the FFA-approved implementation schedule and were approved by EP.\ and SCDHEC in
December 1997.
The post-ROD documents include Corrective Measures Implementation/Remedial Design Work
Plan (CMI/RDWP) and Corrective Measures Implementation/Remedial Design Report/Remedial
Action Work Plan (CMI/RDR/RAWP). In accordance with the FFA-approved implementation
schedule, the Rev. 0 CMI/RDWP and Rev. 0, CMI/RDR/RAWP will be submitted to EPA and
SCDHEC for approval. The Field Start Date for the implementation of the remedial action is
scheduled for April 4, 1999.
III. HIGHLIGHTS OF COMMUNITY PARTICIPATION
Both RCRA and CERCLA require that the public be given an opportunity to review and
comment on the proposed remedial alternative. Public participation requirements are listed in
South Carolina Hazardous Waste Management Regulations (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 FRB OU soils and groundwater. The Administrative Record File
must be established at or near the facility at issue. The SRS Public Involvement Plan (DOE,
1994a) 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, 1969 (NEPA).
The South Carolina Hazardous Waste Management Regulations (SCHWMR) R.61-79.124 and
Section 117(a) of CERCLA, as amended, requires the advertisement of the notice of any
proposed remedial action and mandates that the public be given an opportunity to participate in
the selection of the remedial action. The Statement of Basis/Proposed Plan for the F-Area
Retention Basin (281-3F) (WSRC, 1997d), which is a part of the Administrative Record File,
highlights key aspects of the investigation and identifies the preferred action for remediating the
FRBOU.
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:
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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
University of South Carolina
Columbia, South Carolina 29208
(803) 777-4866
Reese Library
Augusta State University
2500 Walton Way
Augusta, Georgia 30910
(706)737-1744
Asa H. Gordon Library
Savannah State College
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—and through notices in the Aiken Standard, the Allendale Citizen Leader, the Augusta
Chronicle, the Barn-well People-Sentinel, and the State newspapers. The public comment period
was also announced on local radio stations.
The 45-day public comment period began January 20, 1998, and ended on March 5, 1998. A
public briefing was provided in the CAB subcommittee meeting on February 23, 1998. In the
meeting, SRS briefed the public regarding the path forward for the remediation of FRB. At the
meeting, a concern was raised over the need to grout the contaminated soil in addition to capping
the basin soil. Consequently, an extension for the public comment period was granted, extending
the period to April 4, 1998. A formal public comment was also received which questioned the
risk reduction and necessity of soil grouting. CAB recommendation No. 56 (Appendix A) was
also received on March 28, 1998. The SRS response to this concern is provided with this ROD
in the Responsiveness Summary (Appendix A). It will also be available with the final RCRA
permit. The response to public comment and CAB recommendation has been accepted by EPA
and SCDHEC.
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IV. SCOPE AND ROLE OF THE OPERABLE UNIT WITHIN THE SITE
STRATEGY
RCRA/CERCLA Programs at SRS
RCRA/CERCLA units (including the FRB) at SRS are subject to a multi-stage remedial
investigation process that integrates the requirements of RCRA and CERCLA as outlined in the
RFI/RI Program Plan (WSRC, 1993b). The RCRA/CERCLA process summarized in Figure 4
consists of investigation and characterization of potentially impacted environmental media (such
as soil, groundwater, and surface water) comprising the waste unit and surrounding areas; the
evaluation of risk to human health and the local ecological community; the screening of possible
remedial actions to identify the selected technology which will protect human health and the
environment; implementation of the selected alternative; documentation that the remediation has
been performed competently; and evaluation of the effectiveness of the technology. The steps of
this process are iterative in nature and include decision points which involve concurrence
between the DOE (as owner/manager), the EPA and SCDHEC (as regulatory oversight), and the
public. The RCRA/CERCLA process was used for the characterization of the FRB OU, and for
developing the remedial alternatives and finally selecting the remedial action.
F-Area Retention Basin (281-3F) Remedial Strategy
The FRB OU includes the retention basin (basin soils), the former process server line (pipeline,
pipeline sediment, and pipeline associated soils), and groundwater associated with the unit. The
F-Area Retention Basin is located within the Fourmile Branch Watershed (see Figure 1). Several
source control and groundwater operable units within this watershed will be evaluated to
determine future impacts, if any, to the associated streams and wetlands. It is the intent of SRS,
EPA, and SCDHEC to manage these sources contamination to minimize impact to the watershed.
Presently, based on the characterization and risk assessment information, the FRB OU does not
significantly impact the watershed. The investigation and sampling for the FRB OU considered
all unit specific groundwater. Based on the results of the investigation of the groundwater, the
contamination in the water table aquifer is not attributable to the wastes associated with FRB
OU. Upon disposition of all the 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.
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The preliminary investigation conducted for the FRB OU identified two primary sources of
contamination: (1) the former basin; and (2) the process sewer line leading from the F-Area
Canyon Facility and the F-Area Tank Farm to the FRB. To characterize the FRB OU and to
identify the primary sources of contamination and primary contaminated media, numerous
environmental investigations were conducted at the unit between 1993 and 1997. The
Groundwater Sampling Report with Residential Risk Assessment for the F-Area Retention Basin
(WSRC, 1997a) and the Remedial Investigation with the Baseline Risk Assessment Report for the
F-Area Retention Basin (WSRC, 1997b) contain detailed analytical data for all the
environmental media samples taken in the characterization of the FRB OU. These reports are
part of the Administrative Record File (see Section III). The primary media of contamination
determined included soils associated with the former basin area primarily the subsurface soils
(deeper than 1.2 m [4 ft]); the surface [0-0.6 m (0-4 ft) and subsurface soils associated with
process sewer line area; and sediment within the sewer pipeline. Only human health COCs (i.e.,
Cs-137, Ra-226, K-40, thallium) were identified in the surface soil and only one CMCOC (Sr-
90) was identified in the subsurface soil. Radionuclide contaminants in subsurface soil (deep
soils, 6-14 feet) represent a principal threat source material (i.e., highly toxic or highly mobile
contaminants which would present a significant risk to human health or the environment should
exposure occur). No COCs associated with FRB OU were identified for the groundwater. To
address the remediation of FRB OU soils, various potential remedial alternatives were developed
and evaluated. After evaluation, the alternatives S5 and P4 were selected as the preferred
remedies for FRB OU soils and sewer pipeline, respectively. For the groundwater, no action was
selected as the preferred remedy. However, groundwater monitoring is included as an integral
part of S5 alternative to monitor the effectiveness of the remedial action against any future
leaching of Sr-90; to mitigate any uncertainty in the environmental data collected during the
investigations; and to confirm that there are no upgradient sources to the FRB OU groundwater.
In the event, monitoring detects contamination above MCLs (or RBCs) for those constituents
attributable to the FRB OU or an unknown upgradient source, for two consecutive monitoring
periods, the regulators will be informed within 30 days. A plan for evaluating the data and
developing further action will be submitted within 90 days for regulatory approval. The plan
will also include a schedule for assessing the need for corrective action and a schedule for
developing the specifics for that corrective action.
The preferred remedies meet the remedial action objectives of the remedial actions, as described
in Section VII of the ROD, for the former basin area soil and groundwater as well as the soils
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Figure 4. RCRA/CERCLA Logic and Documentation
SRS RCRA/CERCLA UNIT L
1
r
PRELIMINARY EVALUATION
•Unit Reconnaissance
•Unit Screening
RFI/RJ WORK PLAN
• Develop Conceptual Site Model CSM
• Identify Data Needs
• Develop Data Quality Objectives and
Decision Logic
• Detailed Sampling and Analysis Plan
I
UNIT/SITE CHARACTERIZATION
• Implement RFI/R1
• Data Evaluation Vs. DQOs
• Re-Evaluate CSM
Characterization
Complete?
Additional
Characterization
Characterization
Complete?
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Figure 4. (Cont'd). RCRA/CERCLA Logic and Documentation
Treatability Studies
(as necessary)
RFI/RJ REPORT
Establish Remedial Action
Objectives
NO ACTION REMEDY
Baseline Risk Assessment
• Determine Unit Risk
• Develop RGs
CMS/FS REPORT
Identify Response Actions
Identify Technologies
Alternatives Development
Alternatives Screening
Detailed Analysis
SB/PP
Preferred Alternative
Draft Permit Modification
Public Comment
RECORD OF DECISION
Select Remedy
Responsiveness Summary
Final Permit Modification
CORRECTIVE MEASURE/
REMEDIAL ACTION
• Unit closure
• Post Closure Documentation
(Post Construction Report)
POST ROD
DOCUMENTATION
• Remedial Design
Work Plan/Report
• Remedial action
Work Plan/Report
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associated with the process sewer line area and significantly contribute toward the overall
protection of the groundwater as a resource.
V. OPERABLE UNIT CHARACTERISTICS
Media Assessment
The primary sources of contamination associated with the FRB OU are the former basin and
abandoned process sewer line. A Conceptual Site Model (CSM) (Figure 5) was developed for
both the basin and the process sewer line to identify the primary sources, primary contaminated
media, migration pathways, exposure pathways, and potential receptors for FRB OU. The
detailed analytical data for all the environmental media samples taken in the characterization of
the FRB OU are contained in two reports: The Remedial Investigation with the Baseline Risk
Assessment Report for the F-Area Retention Basin (U) (WSRC 1997a); and Groundwater
Sampling Report with Residential Risk Assessment for the F-Area Retention Basin (WSRC
1997a). The documents are available in the Administrative Record File (see Section III).
The primary data used for the RJ/BRA report was collected during the environmental
investigations conducted at the unit between 1993 and 1995. These investigations included a
soil-gas survey, soil sampling, groundwater sampling, and field measurement of radionuclides.
Also, two horizontal bore holes were drilled and monitored for radionuclides in real-time using
Environmental-Measurement-While-Drilling Gamma Ray Spectrometer System Technology.
Surface and subsurface soil samples were collected in the area of the former basin, in the
adjacent basin overflow area, and in the area along the abandoned process sewer line. Samples
were also collected from residual water and sediments in the sewer pipeline. Figure 6 shows
sampling locations in and around the F-Area Retention Basin. All samples were analyzed in
accordance with EPA-approved protocols. Results of the environment investigation and
subsequent analysis indicate the following:
• Groundwater quality has not been adversely affected at this site
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Figun
? 5. Revised Conceptual Site Model for the F-Area Retention Basin and Process Sewer Line
PRIMARY
PRIMARY RELEASE
SOURCE MKCHANISM
Overtopping
Former A
»""» * F.r«k,n
Area
, "1
i
1
f
Proctii *• Infiltration*
Scner I'mutorlot:
Line
1
1
! i _^
i
i
L _
1 WFNII
SECONDARY
SECONDARY RELEASE PATHWAY
SOURCE MECHANISM (Media)
HI Air
VoblUhalkin !_•. _»_
.
Generation < Participates)
1 1
Sulk Direct Contact
EXPOSURE
KOUIE
I'OI KMIAI. HUMAN KECEI'lOR
Ciinsirncllon
Worker
Industrial
Worker
Oii-tlnlf
Resident
KKk
Driver
Inhalation
NA
NA
NA
Inhalation
Direct Contact
NA
NA
IE-S
Cs-137, K-40
digestion
Dermal Contact
. Kllcrnal Radiation
NA
NA
NA
NA
NA
NA
NA
NA
NA
digestion
Inhalation
Dermal COMJCI
Eilcrnal Radiation
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
digestion
Inhalation
Dermal Contact
NA
NA
NA
MCI.
> Ucnudlul (iiuU
NA
NA
NA
(VIJ7. ('U-2JW24U
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Figure 6. Sampling Locations in and Around the F-Area Retention Basin
D—UI.O
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• Levels of Sr-90 in soil beneath the basin represent a risk that future contaminant migration
could result in contamination of the groundwater
• Levels of contaminants (example Sr-90 and Cs-137) at depth represent principal threat source
material (i.e., highly toxic or highly mobile contaminants that would present a significant risk
to human health or the environment should exposure occur).
• Levels of the remaining radioactive and non-radioactive contaminants in soil beneath the
basin do not represent a risk that future contaminant migration could result in contamination
of the groundwater
• Levels of several contaminants (e.g., Cs-137) in surface soil represent a potential risk to
human health
• Levels of contamination in the surface soil and beneath the basin do not represent a risk to
ecological receptors
Nature and Extent of Contamination
The CSM was developed for two primary sources: (1) the former basin area; and (2) the process
sewer line area. The CSM also identified primary as well as secondary release mechanisms for
both sources.
During characterization, primary contamination sources and release mechanisms were also
identified using CSM. The results of the investigations and CSM are summarized below.
Primary Sources and Release Mechanisms
The primary release mechanisms for contamination from the former basin area are
infiltration/percolation of contaminants to groundwater and overflow of the basin. The overflow
of the basin could result in the discharge of contaminants to surface soils and to the nearby
drainage ditch. The sole primary release mechanism identified by CSM for contaminants
associated with the process sewer line area is the escape of contaminants through defects in the
line, followed by percolation of contaminated water to the groundwater.
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Secondary Sources and Release Mechanisms
The CSM identified surface soil and subsurface soil (deep soil) in the basin and around the
perimeter of the basin as secondary sources for the former basin area. The surface soil and
subsurface soil (deep soil) along the abandoned process sewer line were also identified as
secondary sources for the abandoned process sewer line. The sediment in the process sewer line
is an additional secondary source for the process sewer line.
The secondary release mechanisms for the basin surface soil included volatilization, fugitive dust
generation, biotic uptake, and runoff. Leaching was identified as the secondary release
mechanism for subsurface soils. The secondary release mechanisms for the process sewer line
included volatilization, fugitive dust generation and biota uptake for surface soil and leaching for
the subsurface soils. No secondary release mechanism was identified for the sediment in the
process sewer line.
Unit Specific Constituents
Constituent concentrations found in soil, groundwater, and surface water were compared against
twice the background concentrations. The groundwater concentrations were compared with EPA
primary Drinking Water Standards (i.e., MCLs) or twice the mean background concentrations,
where no MCL exists. Unit constituents that exceeded twice the background concentration were
considered Unit-Specific Constituents (USCs). These USCs were used to define the nature and
extent of contamination at the unit and were evaluated in detail in the RI/BRA report to reflect
risk to human health or the environment. Table 1 contains the list of USCs identified for the
FRB source OU. These include 7 inorganics, 16 organics, and 22 radionuclides.
Former Basin Area
USCs were detected in subsurface soils within the former basin area. The metals arsenic and
beryllium and several radiological parameters exceeded maximum screening level
concentrations. Primarily, Cesium-137 and Strontium-90 were the radiological parameters with
the highest detected concentrations. Their concentrations exceeded twice the background
concentrations by factors of 38,000 and 2,570, respectively. Europium-154 also exceeded the
maximum screening level concentration for deep soils. Beryllium slightly exceeded its
maximum screening level in one surface soil sample. Cesium-137 and Radium-226 (a naturally
occurring isotope) slightly exceeded their maximum screening levels in several surface and
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Table 1. Unit-Specific Constituents Identified for the FRB Source Operable Unit
Inorganics
Organics
Radionurlides
Arsenic
Barium
Beryllium
Chromium
Lead
Nickel
Thallium
Acetone
Carbon disulfide
2-Chlorophenol
Dibenzofuran
1,1-Dichloroethane
Dichloromethane
Di-n-butyl phthalate
Ethylbenzene
Methyl ethyl ketone
N-Nitrosodiphenylamine
Styrene
Tetrachloroethene
Toluene
Trichloroethylene
Trichlorofluoromethane
Xylenes
Actini'\n-228
Americium-241
Carbon-14
Cesium-137
Cobalt-57
Cobalt-60
Europium-154
Europium-155
Lead-212
Nickel-63
Plutonium-238
Plutonium-23 9/240
Potassium-40
Promethium-147
Radium-226
Sodium-22
Srrontium-90
Technetium-99
Thorium-234
Uranium-233/234
Uranium-235
Uranium-238
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shallow subsurface soil samples taken in the basin area. USCs were also identified in surface
soils and shallow subsurface soils within the former basin area. However, 'hese USCs are not
associated with operation of the basin since the former basin was backfilled in 1978 with clean
soil. Hence, only USCs identified in subsurface soils could be attributable to past operations.
USCs were also detected in soils adjacent to the former basin (overflow area). Beryllium,
Cesium-137, Thallium, Radium-226, and Plutonium 239/240 were detected and exceeded twice
the background levels. These detections, however, closely matched the detected levels in the
background borings and did not exhibit any discernible pattern of contamination. Therefore, the
soils in the basin overflow area do not appear to have been adversely impacted by basin
overflow.
Process Sewer Line Area
USCs were detected in residual water in the abandoned process sewer line and manholes.
Primarily, Cesium-137 and Strontium-90 were the radiological parameters with the highest
detected concentrations. Cesium-137 exceeded its maximum screening level concentration by a
factor of 327 while Strontium-90 exceeded its maximum screening level concentration by a
factor of 94.4. These were also the largest margins by which the maximum screening level
concentrations were exceeded.
USCs were detected in residual sediments in the abandoned process sewer line. The inorganic
constituents Arsenic and Beryllium exceeded their maximum screening level concentrations.
Cesium-137, Strontium-90, and Plutonium-239/240 were the radiological parameters with the
highest detected concentrations that exceeded their maximum screening level concentrations.
The concentrations exceeded their twice background levels by factors of 24,600, 118, and 86.3,
respectively.
USCs were detected in soils adjacent to the abandoned process sewer line. Arsenic and
Beryllium were the inorganic constituents that exceeded maximum screening level
concentrations. The radiological parameters that exceeded maximum screening level
concentrations were Cesium-137 and Strontium-90. Their maximum concentrations occurred in
deep samples and exceeded their twice background levels by factors of 368 and 51.9,
respectively.
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Groundwater
The only contaminant detected (a single delect) in groundwater was trichloroethylene at
sampling location FRB-2 (see Figure 6), but it was also detected in the background well. This
could indicate that the trichloroethylene originated from an area hydraulically upgradient from
the site, particularly since a trichloroethylene source was not found in the soil. Metals other than
common cations were not detected consistently. Only one radiological analyte was detected
above twice background concentrations, and only in one round of sampling. However, based on
the data collected in January 1997 and February 1997, activities associated with the former basin
do not appear to have impacted the groundwater.
Groundwater Transport Analysis
In response to a recommendation from the Citizens Advisory Board (CAB), transport modeling
was performed for the most prevalent radioactive constituents (e.g., Sr-90 and Cs-137). This
analysis was performed using RESRAD modeling for leachability of contaminants. Results of
this analysis indicate that only Sr-90 is predicted to reach the groundwater at levels which exceed
relevant standards. This analysis supersedes overly conservative calculations reported in the
RFI/BRA which indicated that TC-99 and Sr-90 could potentially contaminate groundwater.
However, the remedy to stabilize the Sr-90 will also reduce the mobility of Tc-99 and the other
radioactive contaminants present in the soil.
VI. SUMMARY OF OPERABLE UNIT RISKS
As part of the F-Area Retention Basin RFI/RI process, a baseline risk assessment (BRA) was
prepared to evaluate the potential risk to human health and the environment from chemical and
radioactive contaminants identified in investigations at the FRB. The following sections outline
the results of the human health and ecological risk characterizations conducted as part of the
assessment. A complete discussion of the risk assessment methodology, receptor analysis, risk
characterizations, and uncertainty within the characterizations can be found in the Groundwater
Sampling Report with Residential Risk Assessment for the F-Area Retention Basin (WSRC,
1997a) and the Remedial Investigation with the Baseline Risk Assessment Report for the F-Area
Retention Basin (WSRC, 1997b).
Unit-specific data from the RFI/RI were used to identify and screen constituents of potential
concern (COPCs). Exposure point concentrations were calculated and used to estimate potential
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exposures and risks to humans and wildlife. Carcinogenic risks and hazard indices (His), based
on a combination of exposure scenarios, locations, and receptors identified in the CSM, were
calculated and then compared to EPA risk guidelines [i.e., 1 x 10"4 to 1 x 10"6 carcinogenic risk,
HI > 1, and ecological effects quotient (EEQ) > 1]. COPCs were screened and identified as
preliminary COCs (PCOCs) and designated as primary or secondary COCs, based on their
individual contribution to total media risk or hazard.
Human Health Risk Assessment
To evaluate the risk to human receptors due to the contamination at the FRB, unit-specific
analytical data are used to identify COPCs. Exposure point concentrations are determined for
each COPC to estimate the potential exposure for various receptors and exposure scenarios. The
current land use scenario is inactive industrial use and an infrequent on-unit visitor (researcher or
sampler) was postulated but quantitative risks were not determined for this receptor because SRS
programs and procedures are implemented to protect workers from harmful exposure to
contaminants at waste units. Receptors for the future land use exposure scenario identified for the
former basin area included an on-unit industrial worker and an on-unit resident (adult/child).
Receptors identified for future land use at the process sewer line area included an on-unit
industrial worker, an on-unit resident (adult/child), and an on-unit construction worker
(Figure 5).
Following the selection of human receptors for evaluation, the carcinogenic risks and the
noncarcinogenic health hazards were estimated for each COPC and for each pathway/receptor
combination based on EPA guidance (EPA, 1989b).
Carcinogenic risk is defined as the incremental probability of an individual developing cancer
over a lifetime as a result of pathway-specific exposure to cancer-causing contaminants. 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. At Superfund
sites incremental risk from carcinogens is compared to the EPA target risk range of one in ten
thousand (1 x 10"4) to one in one million (Ix 10"6).
Noncarcinogenic hazards are also evaluated to identify a level at which there may be concern for
potential noncarcinogenic health effects. The hazard quotient (HQ), which is the ratio of the
exposure dose to the reference dose, is calculated for each contaminant. HQs are summed for
each exposure pathway to determine the specific HI for each exposure scenario. If the HI exceeds
unity (1.0), there is the potential for adverse health hazards.
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Former Basin Area
Future Land Use Carcinogenic Risks
The future on-unit industrial worker has three exposure routes with carcinogenic risks within the
target range of 1 x 10^ to 1 x 10"* (Table 2). External radiation exposure to surface soil has a nsk
of 2 x 10"5 primarily due to Cs-137 and Ra-226. Ingestion of subsurface soil has a risk of 2 x 10 6
primarily due to arsenic. External radiation exposure to subsurface soil has a risk of 9 \ 10"
primarily due to Cs-137 and Ra-226. The risks for the future worker from all other pathways are
less than the EPA action level (1 x 10'*).
Several pathways for the future on-unit resident have estimated risks within the target range
(Table 2). External exposure to radionuclides in surface soil has a risk of 2 x 10"4 primarily due to
Cs-137, K-40, and Ra-226. Ingestion of produce grown on surface soil has a risk of 1 x 105
primarily due to plant uptake of Cs-137 and K-40. Exposure to subsurface soil has a risk of
8x 10"6 from ingestion primarily due to arsenic, Pu-239/240, Ra-226, and Cs-137. External
exposure to radionuclides in subsurface soil has a risk of 8 x 10"5 primarily due to Cs-137 and
Ra-226. Ingestion of produce grown on subsurface soil has a risk of 5 x 10'* primarily due to
plant uptake of Cs-137 and K-40. RESRAD modeling indicates that the MCL for Sr-90 (8 pCi/L)
will be exceeded by leaching from deep soils (>4 feet deep) with the peak concentration of 79
pCi/L reached in 76 years (E7 Calc Note reference).
Nonbarcinogenic Hazards
The BRA shows that potential adverse noncarcinogenic health effects are not likely to occur for
the future on-unit worker because the sum of His for all pathways evaluated is less than the value
of 1.0 (Table 2).
The His for hypothetical future resident exposures equal or exceed 1.0 for the ingestion of
surface soil (0-1 foot) and subsurface soil (0-4 feet) (Table 2). The HI for ingestion of surface
soil equals 1 and is primarily the result of thallium. The HI for ingestion of subsurface soil equals
2 and is primarily the result of thallium and arsenic.
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Table 2. Summary of Risk-Based COPCs, Grouped by Exposure Route
Receptor *
Former Basin Area
Hypothetical Future
Worker
Hypothetical Future
Resident
Process Sewer Line
Area
Hypothetical Future
Worker
Hypothetical Future
Construction Worker
Hypothetical Future
Resident
Exposure Route/Medium
External Radiation /
Surface Soil
External Radiation /
Subsurface Soil
Ingestion / Subsurface Soil
External Radiation /
Surface Soil
Ingestion / Surface Soil
Ingestion / Produce Grown
on Surface Soil
External Radiation /
Subsurface Soil
Ingestion / Subsurface Soil
Ingestion / Produce Grown
on Subsurface Soil
Ingestion / Deep Soil
Leaching to Groundwater
External Radiation /
Surface Soil
External Radiation /
Subsurface Soil
External Radiation /
Surface Soil
External Radiation /
Subsurface Soil
Ingestion / Sediments within
Pipeline & Manholes
External Radiation /
Surface Soil
Ingestion / Surface Soil
Engestion / Produce Grown
on Surface Soil
External Radiation /
Subsurface Soil
Ingestion / Subsurface Soil
Ingestion / Produce Grown
on Subsurface Soil
Preliminary COCs
Cs-137. Ra-226
Cs-137. Ra-226
As
Cs-137, K-40. Ra-226
Tl
Cs-137, K-JO
Cs-137, Ra-226
As, Tl, Pu-239/240, Ra-226, Cs-137
Cs-137, K-40
Sr-90
Cs-137, Ra-226, Ac-228
Cs-137, Ra-226. Ac-228
Cs-137, Ra-226
Cs-137, Ra-226
As. Cs-137, Pu-239/240
Cs-137. Ra-226. Ac-228
AS
Cs-137. K-40
Cs-137. Ra-226. Ac-228
As. Ra-226. Sr-90
Cs-137, K-40
Carcinogenic
Risks
2x 10'5
9x 10-"
2x JO"6
2x 10"
Ix 1(T
8x 10'5
8x lO'5
5x 1CT
Exceedance
of MCL
1 x 10'5
9x 10"*
4x ID'6
4 x 106
8 x lO'6
IX ID"4
3 x 10'6
5x lO'6
Ix 10"
5x 10'6
5 x 10'6
Hazard
Index
1
2
o Ecological Receptors were identified as being impacted by UisLs.
As •» arsenic K-40 - Potassium-40
Tl = Thallium • Pu-239/240«Plutonium-239/240
Cs-137-Cesium-137 Ac-228 • Actinium-228
Ra-226 = Radium-226 Sr-90 - Strontium-90
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Total Pathway Risks and Hazard Indices
Carcinogenic risks and noncarcinogenic hazards associated with the individual exposure
pathways for surface soil (0-1 ft) and subsurface soil (0-4 ft) have been summed to obtain total
pathway risks and His for each receptor (worker and resident).
The total pathway risk values for the hypothetical future on-unit worker and hypothetical future
on-unit resident are 3 x 10"5 and 3x10"*, respectively. The risk values that exceeded the EPA
point of departure (1 x 10"*) for the future receptors are a result of exposure to constituents in
soil. Additionally, leaching of Sr-90 from deep soil to the groundwater will exceed the MCL by
almost 10-fold in 76 years.
Total pathway His exceeded 1.0 for the future on-unit resident. These His were 1 [for pathways
excluding subsurface soil (0-4 ft)] and 2 [for pathways excluding surface soil (0-1 ft)]. The
noncarcinogenic hazards for the future on-unit resident were a result of exposure to metals in
surface and subsurface soil.
Process Sewer Line Area
Future Land Use Carcinogenic Risks
The future on-unit industrial worker has two exposure routes with carcinogenic risks within the
target range of 1 x 10"* to 1 x 10'6 (Table 2). External radiation exposure to surface soil has a risk
of 1 x 10"5 primarily due to Ra-226, Cs-137, and Ac-228. External radiation exposure to
subsurface soil has a risk of 9 x 10"6 primarily due to Ra-226, Cs-137, and Ac-228. The risks for
the future worker from all other pathways are less than the EPA action level (1 x 10'").
The future on-unit construction worker has two exposure routes with carcinogenic risks within
the target range of 1 x 10"4 to 1 x 10"6 (Table 2). External radiation exposure to surface soil has a
risk of 4 x 10"* primarily due to Ra-226 and Cs-137. External radiation exposure to subsurface
soil has a risk of 4 x 10"6 primarily due to Ra-226 and Cs-137. Ingestion of sediments contained
within the pipeline and manholes has a risk of 8 x 10" primarily due to arsenic, Cs-137, and Pu-
239/240. The risks for the future worker from all other pathways are less than the EPA point of
departure (1 x 10"6).
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Several pathways for the future on-unit resident have estimated risks within the target range
(Table 2). Ingestion of surface soil has a risk of 3 x 10"" primarily due to arsenic. External
exposure to radionuclides in surface soil has a risk of 1 x 10"1 primarily due to Cs-137, Ac-228,
and Ra-226. Ingestion of produce grown on surface soil has a risk of 5 x 10"6 primarily due to
plant uptake of Cs-137 and K-40. Exposure to subsurface soil has a risk of 5 x 10'6 from
ingestion primarily due to arsenic, Ra-226, and Sr-90. External exposure to radionuclides in
subsurface soil has a risk of 1 x 10"* primarily due to Ac-228, Cs-137, and Ra-226. Ingestion of
produce grown on subsurface soil has a risk of 5 x 10~6 primarily due to plant uptake of Cs-137
and K-40.
Non carcin ogenic Hazards
The BRA shows that potential adverse noncarcinogenic health effects are not likely to occur for
the future on-unit worker, construction worker, and resident because the sum of His for all
pathways evaluated is less than the value of 1.0 (Table 2).
Total Pathway Risks and Hazard Indices
Carcinogenic risks and noncarcinogenic hazards associated with the individual exposure
pathways for surface soil (0-1 ft), subsurface soil (0-4 ft), and sediment in the pipeline and
manholes have been summed to obtain total pathway risks and His for each receptor (worker and
resident).
The total pathway risk values for the hypothetical future on-unit worker, future construction
worker, and hypothetical future on-unit resident are 1 x 10"5, 3 x 10"2 and 5 x 10"4, respectively.
The risk values that exceeded the EPA point of departure (1 x 10"*) for the future receptors are a
result of exposure to constituents in soil.
Total pathway His did not exceed the threshold of 1.0 for any of the exposure pathways.
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Table 3. Contaminants of Concern for Soil at the FRB Operable Unit with Maximum
Detected Concentrations and Remedial Goals
Former Basin Area
Medium
Surface Soil
(0-1 foot)
Subsurface Soil
(0-4 foot)
Groundwater
(current)
Leachability to
Groundwater
from FRB Soil
Analyte
Cesium-137
Potassium-40
Radium-226
Thallium*
Arsenic
Cesium-137*
Potassium-40
Radium-226
Thallium*
None
Strontium-90
Maximum Detect
0.29 pCi/g
2.49 pCi/g
0.931 pCi/g
6.12 mg/kg
7.13mg/kg
10.9pCi/g
3.04 pCi/g
0.931 pCi/g
6.93 mg/kg
N/A
79 pCi/L @ 76 yrs
(modeled level)
KG for soil
0.74 pCi/g
2.53 pCi/g
0.226 pCi/g
25.9 mg/kg
11.1 mg/kg
0.74 pCi/g
2.53 pCi/g
0.226 pCi/g
25.9 mg/kg
N/A
109pCi/g**
Process Sewer Line Area
Medium
Surface Soil
(0-1 foot)
Subsurface Soil
(0-4 foot)
Groundwater
(current)
Sediment within
the Pipeline &
Manholes
Analyte
Arsenic*
Actinium-228
Cesium-137
Lead-212*
Potassium-40
Radium-226
Arsenic*
Actinium-228
Cesium-137
Lead-212*
Potassium-40
Radium-226
Strontium-90
None
Arsenic*
Cesium-137*
Plutonium-239/240*
Maximum Detect
20.8 mg/kg
1.57pCi/g
2.69 pCi/g
1.65pCi/g
2.42 pCi/g
1.21 pCi/g
17. 7 mg/kg
2.51 pCi/g
21.3pCi/g
2.44 pCi/g
1.49pCi/g
2.60 pCi/g
21.8pCi/g
None
16.3 mg/kg
2040 pCi/g
32.2 pCi/g
KG for soil
11.1 mg/kg
0.202 pCi/g
0.74 pCi/g
2.19pCi/g
2.53 pCi/g
0.226 pCi/g
11.1 mg/kg
0.202 pCi/g
0.74 pCi/g
2.19pCi/g
2.53 pCi/g
0.226 pCi/g
233 pCi/g
N/A
63.9 mg/kg
l.lpCi/g
26.3 pCi/g
Secondary COCs
** RG is the level of leachable contaminants from FRB soil that will not exceed the MCL in the
future. The RG is derived from the RESRAD modeling for leachability (K-CLC-F-00030). The
MCL for Strontium-90 is 8.0 pCi/L (CFR 1991).
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Ecological Risk Assessment
The BRA also addressed the ecological risk associated with the former basin area and the process
sewer line area. Risks from both nonradionuclide and radionuclide constituents were evaluated.
Quantitative risk estimations were based on a comparison of estimated intake to a predetermined
toxicity reference value, expressed as a HQ. The assessment concluded that no ecological risk is
associated with FRB OU.
Constituents of Concern
COCs were selected for the FRB because they exceed ARARs, because they exceed risk-based
criteria in the BRA, or because they are projected to have the potential to leach to the
groundwater at levels exceeding a maximum contaminant level (MCL). Primary COCs are
defined in the human health risk assessment as constituents that contribute a chemical-specific
risk of more than 1 x 10'6 or an HQ of greater than 0.1 to any media risk estimate that exceeds a
1 x 10"* risk or an HI of 3. COCs projected to exceed an MCL due to soil leachability are also
considered primary COCs. Secondary COCs are defined as those constituents in each medium
contributing a chemical-specific risk greater than 1 x 10'6 or a HQ of at least 0.1 to a media with
a risk greater than 1 x 10~6, but not more than 1x10^, or a HI of one or greater, but not more than
three. Final COCs are listed in Table 3. A pictorial representation of the distribution of Sr-90
where the soil concentration exceeds the leachability limit of 109 pCi/g (that would exceed the
MCL of 8.0 pCi/L) is included in Figure 7. Figures 8 and 9 show that the Sr-90 concentrations
outside of the basin area are below levels of concern.
Principal Threat Source Material
Evaluated levels of radioactive contaminants in the FRB OU soils at depth meet the definition of
principal threat source material. Principal threat source materials are those contaminants that are
highly toxic or highly mobile and would represent a significant risk to human health or the
environment should exposure occur. Cs-137, Ra-226, thallium, arsenic, and Sr-90 are present in
the FRB OU soils at depth with Cs-137 and Sr-90 representing the highest levels. Distribution of
Sr-90 by depth is shown in Figures 7, 8, and 9. Figures 10 through 12 present the distribution of
Cs-137 by depth. Principal threat source material at depth are shown in Table 4.
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Table 4. Principal Threat Source Material Contamination at Depth for the FRB
Operable Unit with Their Maximum Detected Concentrations
Medium
Former Basin Area
Subsurface Soil at Depth
Cs-137
Sr-90
Ra-226
2200 pCi/g
1080pCi/g
1.37pCi/g
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Figure 7. Distribution of Sr-90 by Depth-FRB Basin Area
rae-12
o
FRB-13
o
FBB-14
FHB-11
e
FHB-OB
e
1
i
FBB.07^_ _
FRB-10
e
FRB-OS
FHB-19 ?
— • *" "~ ""^- i
.— -" ' \ :
F^.0.
lr.*: P p«
O FRB-i:
Sr-90 Distribution by Depth oa.,r5,0nosc*e
£l«vation
ibov* MSL
Surlio
Elevation:
(-HB-O8
FHB-OO
269.9U
271.90
276 T
275
274
0.346
273
272
Ground Surface
-0.27
2.61
271
270
268
267
266
J Basm '
, Bottom '
1 at f
• 264 ft MSL i
2.24
5.25
5.25
1.75
1.43
1.43
0.0713
0.0713
265
264
•263"
262
•air
23.2
91.3
0.571
0.571
9.99
261
260
259
258
102
102
13.8
13.8
13.4
13.4
257
256
8.35
8.35
8.7
8.7
255
254
1.62
1.62
253
252
251
250
249
248
247
246
245
244
243
242
241
240
|E»cndi RESRAD Soil LMclublllty l«va) el 109 pCi;g that would ticMd lh« MCL ol 8.0 pCI/L.
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Figure 8. Distribution of Sr-90 by Depth - FRB Basin Area
FRB-12
O
FRB-13
O
FRB-14
FRB-11
FRB-10
e
FRB-08
. O
FRB-07
O
FRB-05
FRB-19 O
FRB-06
inlet Prpe
•09
O-TRB-15
Sr-90 Distribution by Depth Drawing nol to ^
Elevation
abov. MSL
ZfB ^
277
276
275
274
273
272
271
270
ZD3
268
267
266
265
264
763
262
261
260
259
258
257
256
255
254
233
252
251
250
249
248
Surtac*
Elevation:
irrto*T» fKD-io rno-us»
tOU.IU H4..l\i £.1 I .~\\) j
/
/
/
/
' G rbund"S uiTa'ce 'I .
_x'
r rfasm
! Bottom
' at
I 264 (t MSL
- JL_.
-O.4ZO
-0.321
•0.321
-u.24a
-0.248
-O.621
-0.621
p ' -2.14- -
3.42
3A1
2.08
2.08
3.28
3. 28
2.37
Z.Jf
/
"-0.27" '
-0.407
-0.407
4.46
4.46
-0.198
-0.198
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Figure 9. Distribution of Sr-90 by Depth - FRB Basin Area
FRB-12
FRS-11
FRB-10
FRB-H
FRM»
e
FRB-C7
o
fas-tit
FRB-1* O
e
FRB-M
e
IrvMPioe
e
FRB-Ot
O FRB-13
Sr-90 Distribution by Depth
Drawing not to scaif
tltvauon
•t>av* MSL
J 'J
272 ^
271
270
269
268
267
266
265
264
763 "
262
260
Z3V
258
257
256
255
254
253
252
251
250
24B
248
sunac*
El«v»aon:
T" &£n
' Bonom
-I it —
1 264 II MSL
j_
foy.iu
•U.4JB
•0.321
•0.321
-0.248
•41.621
•0.621
1
•«^»
^09. uw
srouna sunac*
•^T62"
•0.711
•O.711
•1.05
-1.D5
-0.064
. 4.064
1
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Figure 10. Distribution of Cs-137 by Depth-FRB Basin Area
FRB-12
e
FRB-ll
FRB-10
e
FRB-13
e
FRB-14
FRB-08
e
FRB-OS
FRB-19 9
RB-07^
e
FRB-1S
Cs-137 Distribution by Depth
EiCMdslntfustriilWorkw RQO(a74pCI/g@ IE-tna I«M|)
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Figure 11. Distribution of Cs-137 by Depth-FRB Basin Area
FRB-12
O
FRB-13
O
FRB-14
O-.-J
FRB-11
FRB-10
FRB-08
O
FRB-07
e
FRB-05
FRB-19
O
FRB-06
Iniet Pipe
RB-09
—o -
FRB-15
Cs-137 Distribution by Depth
Elevation
above MSL
278 v
277
276
275
274
273
272
271
270
269
268
267
266
265
264
263
262
261
260
259
258
257
256
255
254
253
252
251
250
249
248
Surface
Elevation:
FRB-14 FRB-15 FRB-09 |
269.70 272.70 277.10 |
/ ^^
| Ground Surface |
X
X "
0.41
0.04
0.04
0.00
0.00
0.00
0.00
/
b7o'7~
0.02
0.02
0.00
0.00
0.00
0.00
0.01
0.01
'
0.02
0.02
-0.01
-0.01
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Figure 12. Distribution of Cs-137 by Depth - FRB Basin Area
FRB-12
FRB-11
FRB-10
FRB-11
FRB-14
FRB-OI
e
FRB-07
e
FRB-05
FRB-11 O
e
FRB-N
e
O
FRB-OI
FR8-1S
Cs-137 Distribution by Depth
titvauon
»bov»M3U
2/3
272 w
Z71
270
261
268
267
266
265
264
263
262
261
260
259
258
257
256
255
254
253
252
251
250
248
248
gurnet
Umtton:
[ mo*i4 mD'iii rno*i^ rKO*ii mo*iu I
»W7I/*I
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VII. REMEDIAL ACTION OBJECTIVES AND DESCRIPTION OF THE
CONSIDERED ALTERNATIVES FOR THE FRB OPERABLE UNIT
Remedial Action Objectives
Remedial Action Objectives (RAOs) specify COCs, media of concern, potential exposure
pathways, and remediation goals. The RAOs are based on the nature and extent of
contamination, threatened resources, and the potential for human and environmental exposure.
RAOs are developed based upon ARARs or other information from the RJ/BRA report. ARARs
are those cleanup standards, standards of control, and other substantive requirements, criteria, or
limitations promulgated under federal, state, or local environmental laws that specifically address
a hazardous substance, pollutant, contaminant, remedial action, location or other circumstance at
a CERCLA site. Initially, remedial technologies are selected based on the RAOs. However, with
additional information, the preferred treatment technologies are modified to achieve the goals.
There are three types of ARARs: action-specific, chemical-specific, and location-specific.
Action-specific ARARs set controls on the design, performance, and other aspects of
implementation of specific remedial activities. Chemical-specific ARARs are media-specific
and health-based concentration limits developed for site-specific levels of constituents in specific
media. Location-specific ARARs consider federal, state, and local requirements that reflect the
physiographical and environmental characteristics of the unit for the immediate area. The action-
specific, chemical-specific , or location-specific ARARs (requirements) and to-be-considered
requirements relevant to establishing remedial action objectives for the FRB OU identified is
shown in Tables 5 through 7.
The RI/BRA report (WSRC, 1997b) has indicated that the secondary sources (i.e., surface soils
contaminated with radionuclides) associated with the former basin and process sewer line pose
significant carcinogenic risks (approximately 2 x 10") to human health by external exposure to
radiation. Since threatened, endangered, or sensitive species are not found at the unit and since it
does not offer attractive or unique cover or forage opportunities for wildlife, ecological receptors
are not at significant risk from the unit. Although limited risk is associated with the pipeline and
manhole sediment (approximately 8 x 10'6), radioactivity detected inside the pipeline sediment
does pose potential future risks associated with this source. The RI/BRA report further indicates
that presently there is no contamination in the water table aquifer attributable to the unit.
Groundwater modeling indicates there exists a future potential for Sr-90 to leach out and enter
the groundwater above MCL. Hence, based on the RI/BRA report conclusions, the feasibility
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study (FS) was conducted to consider actions that could reduce the risks associated with the
former basin area soils, process sewer line area soils, pipeline sediment, and reduce the potential
for the COCs to leach out, and enter the groundwater.
Based on the risks posed by the radionuclides in the soils and pipeline sediment, the general
remedial action objectives for the FRB OU are as follows:
• Reduce risks to human health associated with COCs through
- external exposure to radiological constituents by direct contact with the former basin area
soil, surface water, and sewer line area soil,
- ingestion of former basin area and sewer pipeline area soils and pipeline sediment or
produce grown in soils with radiological constituents, and
• Prevent or mitigate exposure to highly toxic or highly mobile contaminants that represent
principal threat source material.
• Prevent or mitigate the leaching and migration of Sr-90 to unit groundwater. MCL for
Sr-90 is 8.0 pCi/L.
Since groundwater data collected in January 1997 and February 1997 reflected no present risk
from groundwater associated with this unit, no RAO was developed for the groundwater.
Summary of the risks associated with FRB OU (see Table 2) indicates that one exposure scenario
for the former basin area equals or exceeds an excess carcinogenic risk of one in ten thousand (1
x 10"4). This scenario, which is addressed by the RAOs, is external radiation from surface soils
(on-unit resident). The risk is 2 x 10"* and COCs contribution to this risk include Cs-137, K-40,
and Ra-226. Scenarios for which risk is within the one in ten thousand to one in one a million (1
x lO^to 1 x 10"6) range are soil ingestion (industrial worker and on-unit resident), dermal contact
with sediment and surface water (on-unit resident), biota ingestion (on-unit resident), and
external radiation from surface soils (industrial worker).
The scenario for the process sewer line area (pipeline sediment and soils) that equals or exceeds a
risk of 1 x 10"4 for excess cancer is external radiation from surface soils (on-unit resident). The
risk is 1 x 10"* and COCs contributing to this risk include Cs-137, Ra-226, and Ac-228.
Scenarios for which risks are within the 1 x 10'6 to 1 x 1CT4 range are surface soil ingestion (on-
unit resident), sediment ingestion (construction worker), external radiation from surface soil
(industrial worker), and soil and sediment ingestion (on-unit construction worker).
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ROD for the F-Area Retention Basin (281-3F)
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August 1998
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Revision 1.1
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Table 5. Chemical-Specific Requirements
tTTATioMS)
4UCJ-K3U.6
40 OK IV2.12
5L R 01-
58.5(B)(2) and 40
CFR 141.62
SC R 01-
58.5(B)(2) and 40
CFR 141.62
SC K 01-
58.5(B)(2) and 40
CFR 141.62
SC R 01-
58.5(B)(2) and 40
CFR 141.62
SU R 01-
58.5(B)(2) and 40
CFR 141.62
it; K 01-
58.5(B)(2) and 40
CFR 141.62
sc; K 01-
58.5(B)(2) and 40
CFR 141.62
SC K 01-
58.5(B)(2) and 40
CFR 141.62
STATUS
Applicable
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant and
Appropriate
Relevant ana"
Appropriate
Relevant and
Approphate
REQUIREMENT
SUMMARY
The concentration ot paniculate
matter (PM,0) in ambient air shall
not exceed SO ng/mj (annual
arithmetic mean) or 150 ug/m3
(24-hour average concentration).
ine concentration ot radium-226
in land averaged over any area of
ICO square meters shall not exceed
the background level by more than
(1)5 pCi/g, averaged over the first
15 cm (5.9) of soil below the
surface, and (2) 1 5 pCi/g, averaged
over 15-cm (5.9-in) thick layers of
soil more than 15 cm (5.9 in)
below the surface.
Hie proposed M(_'L tor thallium is
1 mg/L
Ihe M(_L tor arsenic is U.U5 mg/L.
Ihe MC-L tor cesium- 13 / is 2W
pCi/L.
1 he proposed MCL tor potassium-
40 is 300 pCi/L.
1 he proposed MCL tor radium-ZZO
is 14.7pCi/L.
The MCL lor strontium-90 is S.U
pCi/L.
Ine proposed ML'L tor plutonium
239/240 is 62. 1 pCi/L.
I he MCL tor actimum-ZZS is 3Z /u
pCi/L.
RtASONTOR
INCLUSION
tanh-movmg activities
will generate airborne
dust thai will have the
potential to exceed the
levels specified. Dust
suppression will likely be
required to minimize
dust emissions.
Radium-220 has been
identified as a COC for
soil.
l hallium has been
identified as a COC for
soil and may leach into
the groundwater.
Arsenic has been
identified as a COC for
soil and may leach into
the groundwater.
Lesium-137 has been
identified as COC for
soil and may leach into
the groundwater.
Potassium-4U has been
identified as a COC for
soil and may leach into
the groundwater.
Kadium-ZZO has been
identified as a COC for
soil and may leach into
the groundwater.
Mrontium-yy has been
identified as a COC for
soil and the RERRAD
shows that it can leach
out and enter the
groundwater.
Plutonium Z3W24U has
been identified as a COC
for soil and may leach
into the groundwater.
Actimum-ZZB has been
identified as a COC for
soil and may leach out
into the groundwater.
Ai;itRNAlIVL(S)
S3. S-l. P.J
SI. S3. S-*. Pi. H-.
SI. S3, S4. Pi. P-. Ul.
G2
SI, S3, S4. PI, P4, Ul.
G2
M
SI. S3. S-4. PI. P4. UIM
G2 ^
SI, S3, S4, PI, P4. Ul.
G2
SI, S3, S4. PI, P4. Ul,
G2
SI, 53, S4. PI, P4. Ul,
G2
SI, S3, S4. PI. P4. Ul.
G2
SI, S3, 54. PI. P4. Ul,
G2
I026cn>pdoc JSB/blb 09/11/98
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ROD for the F-Area Retention Basin (281-3F)
Savannah River Site
August 1998
\VSRC-RP-97-145
Revision 1.1
Page 39 of 74
Table 6. Action-Specific Requirements
IT1'AT1UIN(&)
4ULJ-K 264. JIU
SC R 61.02.0,
Section 111
UUt Order
5820.2A, Chapter
111
5IA1US
Relevant and
Appropriate
Applicable
1H(_
Kty UlKLIVLtrS I
SUMMARY
Cap (or cover) must have
permeability less than or equal
to the bottom liner systems.
Paniculate matter must be
controlled in such a manner
and to the degree that it does
not create an undesirable level
of air pollution.
Low-level radioactive waste
must be managed in a manner
that protects public health and
safety, assures that external
exposure to the waste does not
exceed 25 mrem/yr to any
member of the public, and
protects groundwater resources.
RLASUIN tUK
INCLUSION
ioil and sediment addressed bv
this removal action is not RCRA
hazardous waste. This
requirement is identified as
relevant and appropriate for the
low permeability cover. The
hydraulic conductivity of the
cover will be less than or equal
to the soils at the bottom of the
basin or underneath the former
process sewer line.
banh-movmg activities have the
potential to generate airborne
paniculate matter.
Contaminated soil generated
during this remedial action will
likely be considered low-level
radioactive waste.
AL1LKNAI IN t(isl
S3. b?
i»3. J>4. bx P-J. P5A
51, i>j, i>4. bX PI. P4.
P5A
lOiftcrwp
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ROD for the F-Area Retention Basin (281-3F)
Savannah River Site
August 1998
WSRC-RP-97-145
Revision 1.1
Page 40 of 74
Table 7. Location-Specific Requirements
CIl'AllUiN(M)
I6USL bJI
l6Ub'L6fcl
bt- K ji.02.0.
Section III
UUt Order
5820.2A, Chapter
III
MAI US
Applicable
Applicable
Applicable
Applicable
KtyillKtlVLKM
SUMMARY
I he remedial action must be
conducted in a manner to
conserve endangered or
threatened species.
I he remedial action must be
conducted in a manner to protect
fish or wildlife.
I he remedial action must be
conducted in a manner that
minimizes impacts to migratory
birds and their habitats.
I he remedial action must
minimize the destruction, loss,
or degradation of wetlands.
KLASUiN fOK IJNC'LUSlOrs
I here are threatened and
endangered species at the SRS;
however, as stated in the FRfl
RJ/BRA. this action will not
affect these species.
Ihis remedial action has the
potential to affect wildlife in the
vicinity of the FRB and former
process sewer line. This action
will not affect fish located at the
SRS or in nearby bodies of water.
Migratory bird populations may
be presented in the vicinity of
SRS.
wetlands may be located in the
vicinity of the FRB and former
process sewer line; however, they
will be unaffected by this action.
ALItKJNAl l\ L(i»l ,
61. bJ. b-«. bx Cj !. (_!-.
PI, P4. P5A
i>i. b.\ b-». bi. ui. UJ.
PI. P4.P5A
bl, 53. i>4. bX Ui, UJ.
P1.P4.P5 A
bl, bJ. b-4, bX Cil. CJJ,
P1.P4, P5A
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Savannah River Site Revision 1.1
August 1998 Page 41 of 74
Description of the Considered Alternatives for FRB Operable Unit
As part of the investigation/assessment process for the FRB OU, a CMS/FS was performed using
data generated during the assessment phase. The CMS/FS evaluated various treatment processes
and technologies .that can be used to remediate the contaminated soil attributed to the FRB OU
and groundwater. Detailed information regarding the development and evaluation of remedial
alternatives can be found in the Corrective Measures/Feasibility Study for the F-Area Retention
Basin (U) (WSRC, 1997c).
After screening a number of treatment processes and technologies, various treatment alternatives
were developed. Fifteen potential remedial alternatives were identified initially to address the
remediation at the former basin area and the process sewer line area. After initial screening, nine
alternatives were considered for detailed analysis. Since primary and secondary COCs for the
former basin area soil and process sewer line area soil are radionuclides and metals with very
similar physical and chemical properties, the remedial alternatives identified in the FS report are
applicable to all unit primary and secondary COCs.
Considered Alternatives for Soils
Four alternatives were evaluated for remedial action of the soil. Each alternative is briefly
described below. For additional information regarding the description of the alternatives, their
cost estimates and their analyses, see the Corrective Measures/Feasibility Study for the F-Area
Retention Basin (281-3F) (U), (WSRC, 1997c).
Alternative SI - No Action
Under this alternative, no action will be taken for the soil, which means leaving the FRB OU soil
in its current condition with no additional controls. EPA policy and regulations require the
consideration of a No Action alternative to serve as a baseline against which the other
alternatives can be compared.
There is no reduction of risk with this alternative. The only reduction in risks resulting from the
No Action alternative are due to natural decay of radionuclides, primarily Cs-137 and Ra-226.
The half-lives of Cs-137 and Ra-226 are 30 years and 1600 years, respectively. Therefore,
natural decay of Cs-137 and Ra-226 will not reduce the external radiation risk significantly from
a No Action alternative for the next 30 years. Sr-90 could also leach out and enter the
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ROD for the F-Area Retention Basin (281-3F) WSRC-RP-97-145
Savannah River Site Revision 1.1
August 1998 Page 42 of 74
groundwater in 30 years with concentrations above MCL (8.0 pCi/L). The Remedial Action
Objective for principal threat source material would not be addressed under this alternative.
No costs are associated with this alternative. However, the total present worth cost for the five-
year ROD reviews for 30 years (for cost estimating purpose only; actual five-year ROD reviews
will be required in perpetuity), is approximately 59,600.
Alternative S3 - Institutional Controls and Low Permeability Cover
This alternative will include institutional controls and a low permeability cover placed over the
basin. The cover is designed to minimize stormwater percolation. Stormwater percolation is
further minimized by mounding the cover and diverting stormwater by constructing a runoff
control system around the cover. A vegetative cover is placed over the low permeability cover to
minimize erosion (see Figure 13 for illustration). Under institutional controls, deed restrictions
and/or notifications will be provided if the government sells the property. Five-year CERCLA
ROD reviews will also be performed for this alternative for 30 years. The 30-year period is for
cost estimating purposes only; actual five-year ROD reviews will be required in perpetuity.
The institutional controls will involve both short-term and long-term actions. For the short-term
action, signs will be posted at the FRB OU indicating that this area was used for the disposal of
waste material and contains buried waste. Additionally, existing SRS access controls will be
used to maintain use of this site for industrial use only. In the long-term, if property is ever
transferred to non-Federal ownership, the U.S. Government will take those actions necessary
pursuant to Section 120(h) of CERCLA. These actions will include a deed notification
disclosing former waste management and disposal activities as well as any remedial actions
taken on the site and any continuing groundwater monitoring commitments. These requirements
are also consistent with the intent of the RCRA deed notification required at final closure of the
RCRA facility if contamination would remain at the unit. 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 deed
restrictions may be reevaluated at the time of transfer in the event that contamination no longer
poses an unacceptable risk under residential use. Any reevaluation of the need for deed
restrictions would be done through an amended ROD with the Environmental Protection Agency
(EPA) and the South Carolina Department of Health and Environmental Control (SCDHEC)
approval. In addition, if the site is ever transferred to non-Federal ownership, a survey plat of the
1026CTWp O«/22/9«
-------
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<» 2 »
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COYER COMPOSITION
VEGETATION
TOPSOIL (0.5')
CLAY (l.O'l
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STORHVATER PERCOLATION
O
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ROD for the F-Area Retention Basin (281-3F) WSRC-RP-97-145
Savannah River Site Revision 1.1
August 1998 Page 44 of 74
area will be prepared. The plat will be certified by a professional land surveyor, and recorded
with the appropriate county recording agency.
Per the EPA-Region IV Land Use Controls (LUCs) Policy, a Land Use Control Assurance Plan
(LUCAP) and a Land Use Control Implementation Plan (LUCIP) will be developed and
submitted to the regulators for approval. The LUCAP will be submitted under separate cover
whereas the LUCIP will be submitted with the post-ROD documents for the FRB OU.
The LUCIP will clearly identify the objectives of the land use controls for the FRB OU. The
land use control objectives for the FRB OU are to: reduce risks to human health from direct
exposure to radiological COCs by direct contact with basin soil, surface water, sewer line soil,
and ingestion of soils and/or produce grown in FRB OU soils; and prevent leaching and
migration of Sr-90 to groundwater. The specific manner of achieving the land use control
objectives will be included in the LUCEP as part of the post-ROD documents. The LUCIP will
also specify the assumptions made concerning current and expected future land use and exposure
scenarios. The land use scenarios used in the risk assessment as well as the DOE policy on
current and future land use projections are discussed in Section VI.
Under the current land use scenarios, the most reasonable receptor for the FRB OU considered is
a visitor who is exposed to the FRB OU area on an infrequent or occasional basis. Under future
land use scenarios, the receptor and exposure pathways considered included: an industrial
worker exposed to surface soils, redistributed deep soils, and groundwater; a future resident
exposed to surface and excavated deep soils, air, groundwater, homegrown produce and external
radiation; and a construction worker exposed to surface and subsurface soils, groundwater and
sediment within the sewer pipeline. For a construction worker and future resident, both
carcinogenic risks and non-carcinogenic hazards also considered exposure to modeled
concentrations in groundwater due to leachability of soil contaminants. All the assumptions
made concerning current and expected future land use scenarios used in the risk assessment will
also be included in the LUCIP as part of the post-ROD documents. The LUCIP will also specify
those exposure scenarios, which may not be protective of the human health and the environment
under less restrictive land uses.
A low permeability engineered cover will be sufficient to minimize infiltration, intrusion, and
surface erosion. The cover design will be approved by the EPA and SCDHEC prior to
construction. The low permeability cover will encompass an area of approximately 4,000 square
1026crwp doc JSB/Mb OW72/9I
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meters (1.0 acre) and will be maintained for 30 years. The 30-year period is for cost estimating
only; actually the cover will be maintained in perpetuity. Based on the known half-lives of the
predominant radiological risk drivers (i.e., Cs-137 and Ra-226), only Cs-.37 will have gone
through approximately one half-life. In addition, institutional controls will remain in place as
long as the waste remains a threat to human health or the environment.
A properly engineered cover will function as a physical barrier to prevent direct human exposure
to soil-borne contamination and thus will be protective of human health and the environment. A
low permeability cover is a performance-based engineering approach since it does not reduce the
total mass of COCs. The soil cover will be adequate to reduce the annual effective dose
associated with continuous exposure to Cs-137 and Ra-226 to within regulatory limits. In
addition, a properly maintained cover will minimize infiltration and subsequent leaching of
contamination from unsaturated soil to the groundwater.
Under this remedial alternative, two remedial action objectives are satisfied by: (1) limiting
infiltration into the area, thereby reducing the leaching of primary and secondary COCs to unit
groundwater; and (2) preventing human or ecological access, thereby reducing risks to human
health and the environment. The third remedial action objective to prevent or mitigate the
potential exposure to highly toxic or highly mobile contaminants (the principal threat source
material) would not be met.
The total present value estimate for this alternative is approximately $286,000. These costs
include estimated capital costs approximately 5267,000 and operation and maintenance costs,
approximately $19,000, for the cover for 30 years and review, of the remedy every five years for
30 years, as required by the NCP. The 30-year period is for cost estimating purposes only; actual
five-year reviews will be required in perpetuity.
Alternative S4 - Institutional Controls and Grouting
This alternative consists of institutional controls and grouting the soils in situ to reduce
contaminant mobility and stabilize principal threat source material. A vegetative cover will be
installed over the stabilized soil to minimize erosion. The estimated depth range of in situ
grouting is approximately 1.8 to 4.3 m (6 to 14 ft). The depth range, 6 to 14 ft has been selected
for two reasons: (1) Cs-137 and Sr-90 is mostly distributed in the deep soil beneath the former
basin in the depth range of 6 to 14 ft as is apparent from Figures 14 and 15; and (2) the
permeability of the grouted mass will be no greater than 1 x 10"* cm/s, thereby preventing
!02MT»p doc:JSB/blb 09/22/91
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ROD for the F-Area Retention Basin (281-3F) WSRC-RP-97-145
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infiltration to the soils beyond the 14 ft depth. Therefore, Sr-90 and any other contaminants
present in the soil beyond 14 ft depth will have less potential for migrating to the groundwater.
Deed restrictions and/or notifications will be provided if the government chooses to sell the
property. Five-year CERCLA ROD reviews will be performed for 30 years. The 30-year period
is for cost estimating only; the actual reviews will be required in perpetuity.
This alternative will involve excavating the basin to remove the nominal eight feet of clean soil
that was placed in the basin when the basin was closed, cleaned and backfilled in 1978; grouting,
or solidification/stabilization (S/S) of the soil in the bottom of the basin down to a 1.8 m (6 feet)
depth (4.3 m or 14 feet depth from the present surface of the basin, with an approximate volume
of 6,600 m3 or 8,100 yd3); backfilling the basin with clean soil; and grading the top surface of the
basin. Institutional controls will be same as identified in Alternative S3. In situ S/S involves
mixing the S/S reagents into the waste by a mechanical means such as a jet-grouting system or a
long-reach backhoe fitted with a grouting device (see Figures 16 and 17 for illustration). A
treatability study has been conducted on L-Area Oil and Chemical Basin (LAOCB) soils, which
has characteristics almost identical to F-Area Retention Basin soil (Laboratory-Scale
Immobilization Study Report for L-Area Oil and Chemical Basin) (WSRC, 1996). This study has
determined that S/S agents can immobilize unit-specific contaminants; specifically, a mixture of
Portland cement, bentonite, and sodium silicate was found to effectively immobilize
contaminants, primarily radionuclides such as Cs-137 and Co-60.
In situ S/S does not reduce the total mass or toxicity of the COCs. However, it is a proven
performance-based engineering approach that reduces the mobility of the primary and secondary
COCs. Based on the results of a literature search and a treatability study performed on LAOCB
soils, the in situ S/S reagents are considered effective at reducing the leachability of
contaminants. Specifically, the various S/S reagent samples (with LAOCB soil) were subjected
to the toxicity characteristic leaching procedure (TCLP) and the extended American Nuclear
Society (ANS) 16.1 procedure to simulate leaching of contaminants over time. Analysis of the
two leaching tests performed on LAOCB soil samples mixed with S/S reagents demonstrated that
all of the samples released 0.41% and 1.61% or less of gross alpha and gross beta, respectively.
Alternative S4 meets remedial action objectives by: (1) preventing infiltration into the basin area
through immobilizing contaminants present in the basin, thereby preventing migration of primary
and secondary COCs to groundwater; (2) preventing human or ecological access, thereby
reducing risks to human health and the environment; and (3) preventing or mitigating the
lOZttcrwp doc. JSB/blb 09/22/91
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ROD for the F-Area Retention Basin (281-3F)
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August 1998
WSRC-RP-97-145
Revision 1.1
Page 47 of 74
Figure 14. Distribution of Sr-90 by Depth - Depicting the Zone of High
Concentration-FRB Basin Area Alternative S5-Institutional Controls,
Grouting, Low Permeability Cover, and Grounchvater Monitoring
FHB-12
e
FRB-11
O
FBB-10
e
FHB-14
FflB-08
• FRB"U
FBB.07 __._•—• ~~
FRB4S
< T
\ '
FHBJ06
iniei P pe
^^••••^^B
e
FRB-09
O FRB-1S
Sr-90 Grout Zone
Drawing noi to scai«
lEiCMd* RESflAD SeH LuctwbHIty Lent ol 10* pCVfl lh«1 would ne«*d lh« MCL of 8.0 pCI/L.
IQraul Zon* beginning 21«* *bo>« th« biun bottom ind extending lo 6 twl btlow the b««in ballom.
|Bj«in bottom it tt 2M tMt abon mwn M« l«v«l (MSL).
101 lder^vp.doc:JSB^Ib 09/18/98
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ROD for the F-Area Retention Basin (281-3F)
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Revision 1.1
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Figure 15. Distribution of Cs-137 by Depth - Depicting the Zone of High
Concentration -FRB Basin Area Alternative S5- Institutional Controls,
Grouting, Low Permeability Cover, and Groundwater Monitoring
FRB-12
e
FRB-11
FRB-10
FRB-U
e-
FRB-14
FRB-08
e
FRB-07 _ . — •
FRB-OS
RB-07 __
Inie: P:B«
FRB-IS
Cs-137 Distribution by Depth
UMd* Indunriil Werlur RCO (0.74 pCi/g © l£-t riiJi I*M!)
CI!!I!."I!!I3 Grow Zoo.
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Savannah River Site Revision 1.1
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potential exposure to highly toxic or highly mobile contaminants, i.e., the principal threat source
material.
The short- and long-term institutional controls and LUC information described under Alternative
S3 would also be applicable under Alternative S4.
The total present value estimate for this alternative is approximately 51,228,000. These costs
include estimated capital costs approximately $1,209,000 and operation and maintenance costs
approximately 519,000 for the grouted monolith for 30 years and review of the remedy every
five years for 30 years, as required by the NCP. The 30-year period is for cost estimating
purposes only; the actual five-year ROD reviews will be required in perpetuity.
Alternative S5 - Institutional Controls, Grouting, Low Permeability Cover, and Groundwater
Monitoring
Alternative S5 is a combination of alternatives S3 and S4 and consists of grouting the soils in
situ to reduce contaminant mobility and providing a low permeability cover over the grouted
soils. A vegetative cover is placed over the low permeability cover to minimize erosion.
This alternative like S3 will be effective in preventing contact with and ingestion of
contaminated soil. Like Alternative S4, it will also be very effective in reducing potential
leaching of contaminants from soil to groundwater. Additionally, deed restrictions and/or
notification will be provided if the government sells the property. Five-year ROD reviews will
also be performed for this alternative.
Under this alternative, contamination in the basin soil will be immobilized and covered with
clean soil and a low permeability cover as discussed under Alternative S3. These actions would
meet all the three remedial action objectives by:
• preventing infiltration into the soil through cover and immobilizing contaminants present in
the basin via in situ S/S, thereby preventing migration of primary and secondary COCs to
groundwater;
• preventing human or ecological access, thereby reducing risks to human health and the
environment;
I0:<*rwj> dec JSB/blb 09/2WI
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Figure 17. Jet and Soil Mixing Grouting Techniques
TVack Mounted Jet-Grout Drilling
PKvioudjr Grouted A/cu
Crane Mounted Soil/Grout Mixing System
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• preventing or mitigating potential exposure to highly mobile or toxic contaminants which
represent the principal threat source material; and
• reducing the radioactive dose (direct radiation exposure) received from Cs-137 and Ra-226
by nearly 100%, assuming an approximate cover thickness of four feet.
This alternative also includes groundwater monitoring to confirm that the source remediation has
achieved the required stabilization of the contaminants; to relieve any uncertainty in the
analytical data; and to verify that there exists no upgradient source contributing any
contamination to the FRB OU groundwater. The existing monitoring wells (FRB-01, -02, -03,
and -04) will be used to collect groundwater samples semi-annually (see Figure 18 for
monitoring well locations, groundwater flow direction, and location for the upgradient well).
The analytes monitored will include Cs-137, Sr-90, TCE, and other COCs and normal field
measurements specified in the post-ROD document work plans. If monitoring dejects
contamination above MCLs (or RBCs without MCLs) for those constituents attributable to the
FRB OU or an unknown upgradient source, for two consecutive monitoring periods, the
regulators will be informed within 30 days. A plan for evaluating the data and developing further
action will be submitted within 90 days for regulatory approval. The results of the monitoring
will be reported annually; however, no raw data will be provided.
The short-term and long-term institutional controls and LUC information described under
Alternative S3 would also be applicable under Alternative S5.
The total present value estimate for this alternative is approximately $1,461,000 with total
estimated capital costs approximately $1,442,000 and O&M costs approximately $19,000.
This estimate includes costs for groundwater monitoring, operation and maintenance of the cover
for 30 years, and review of the remedy every five years for 30 years as required by the NCP. The
30-year period is for cost estimating purposes only; actual five-year reviews will be required in
perpetuity.
Considered Alternatives for Groundwater
Since no impact to the groundwater from the operation of the basin was discovered, only two
alternatives were evaluated for groundwater. The alternatives are described below.
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Figure 18. Locations of FRB Monitoring Wells and Upgradient Well
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Revision I.I
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553000 EiROO E SJ400 t SJIOO I 53800 E 44000 fMJOO E 54400 E 44«00 E 54»00
— N 16000
LEGEND
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f,C»lf IN (f f I
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Alternative Gl - No Action
This alternative involves leaving the groundwater associated with FRB OU in its current
condition with no additional controls. EPA policy and regulations require the consideration of a
No Action alternative to serve as a baseline against which the other alternatives can be compared.
Because no further action is taken at the unit, the groundwater remains in its present condition.
No costs are associated with this alternative.
Alternative G2 - Groundwater Monitoring
This alternative involves maintaining control of the basin area and monitoring the groundwater
annually until it is confirmed that the remedial response action for the FRB OU has achieved the
required stabilization of the contaminants. This alternative alone will not be effective in
preventing future ingestion of shallow aquifer groundwater. No monitoring is required based on
no basin impact. However, groundwater monitoring was considered as an element of the soil
remedy.
However, groundwater monitoring when performed in conjunction with institutional controls
will be effective in preventing the ingestion of groundwater and thereby reducing the risks to
human health. If contamination is detected above the maximum contamination level, then further
groundwater response actions will be necessary. If monitoring conditions change, SRS will
request alteration or termination of the monitoring program.
The short-term and long-term institutional controls and LUC information described under
Alternative S3 would also be applicable under Alternative G2.
There are no capital costs associated with this alternative; however, total estimated O&M costs
are approximately $114,000. Therefore, the total present worth cost for this alternative is
approximately $114,000. These costs include a five-year ROD review for 30 years. The 30-year
period is for cost estimating purposes only; actual five-year reviews will be required in
perpetuity.
Considered Alternatives for Process Sewer Line
Three alternatives were evaluated for remediation of the process sewer line and pipeline-
associated soils. The alternatives are described below.
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Alternative PI - No Action
This alternative involves leaving the process sewer line, like the basin, in its current condition
with no additional controls. EPA policy and regulations require the consideration of a No Action
alternative to serve as a baseline against which the other alternatives can be compared. Because
no further action is taken at the unit, the process sewer line along with the basin soil remains in
its present condition. There is no reduction in the risk posed by the radionuclides present in the
soil, which include Ac-228, Cs-137, K-40, Ra-226, and Sr-90.
No costs are associated with this alternative. However, the total present worth cost for five-year
ROD reviews for 30 years is approximately $9,600. The 30-year period is for cost estimating
purposes only; actual five-year reviews will be required in perpetuity.
Alternative P4 - Institutional Controls, Pipeline Grouting, Soil Excavation, and Disposal of
Soil with Basin Soil
This alternative includes pumping grout into the pipeline and manholes to stabilize contaminants,
thereby restricting access to the contaminants inside the pipeline. This alternative also involves
excavating localized areas of contaminated soil (areas around the trouble spots determined by
robotics investigation and soil sampling) (Figure 19) around the pipeline area using standard
earth-moving equipment. The volume of contaminated soil will be determined by comparing the
existing sampling data against the acceptance criteria (concentration levels not to exceed 20
pCi/g for alpha and 50 pCi/g for beta and gamma emitters). The material (unacceptable
contaminated soil with an estimated volume of approximately 240 m3 or 300 yd3) is then
transported to the basin for disposal along with the basin soils. Deed restrictions and/or
notifications would be provided if the government were to sell the property. Five-year ROD
reviews are also included in this alternative.
The short-term and long-term institutional controls and LUC information described under
Alternative S3 would also be applicable to P4.
Because the source of contamination is removed under this alternative, the remedial action
objectives are met. The sewer line soil hot spots and, if necessary, associated sections of pipeline
are excavated and combined with the basin grout mass, thereby reducing the risk from the most
contaminated areas of the sewer line soils.
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Figure 19. Location of Potential Trouble Spots
Horn TV* Fern
P37
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The total present worth cost for this alternative is approximately 5320,000 with total estimated
capital costs approximately $310,000 and estimated O&M costs 596,000. These costs include
five-year ROD reviews for 30 years. The 30-year period is for cost estimating purposes only;
actual five-year reviews will be required in perpetuity.
Alternative PSA - Excavation and Off-Unit Disposal (SRS Disposal)
This alternative involves excavating and removing the pipeline and associated contaminated soil
and using clean backfill from an SRS source to return the area to natural grade. Topsoil will also
be used to support a vegetative layer.
Concrete debris (estimated volume of 45 m3 [58 yd3]) generated during removal of the pipeline
will be transported to E-Area Low Level Radioactive Disposal Facility for disposal. Assuming a
150% bulking factor for the concrete pipe, the volume of pipeline that will be broken and sized
into small pieces will be approximately 68mJ (87 yd3). Contaminated soil (estimated volume of
approximately 240 m3 [300 yd1]) will be dispositioned with basin soils.
This alternative meets ARARs. Residual concentrations of Ra-226 in soil will meet the relevant
ARAR. Excavation of contaminated material (pipeline and soil) can be performed in a manner
that meets air emission ARARs; that is, using conventional earth-moving equipment and
standard dust suppression techniques. Current access restrictions prevent inadvertent intrusion
into the area. Risks to remediation workers from operating heavy earth-moving equipment and
handling contaminated soil and sediment can be managed by following the project-specific
health and safety plan. Equipment and materials required for this remedial action are readily
obtained by SRS.
Implementation of this alternative will be difficult as a large amount of soil (2728 m3 [3567 yd3])
must be excavated and managed while removing the pipeline. There will also be difficulties
associated with removing the 0.6 m (2 ft) and 0.9 m (3 ft) diameter pipeline from the ground due
to its size and weight. Another process line (unrelated to this unit and not addressed by this
alternative) runs close to the former process sewer line. Therefore, excavation activities must be
carefully planned and conducted to avoid disturbing this other process line. Disposal capacity at
SRS for the disposal of low-level radioactive waste is also limited. Because the source of
contamination will be removed under this alternative, remedial action objectives will be met by
eliminating any risk to groundwater, human health, and the environment.
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The cost of this alternative is approximately 5410,000 (total present value cost). There are no
O&M costs for this alternative and these costs also do not include costs for five-year ROD
reviews since no ROD review will be required for this alternative.
VIII. SUMMARY OF COMPARATIVE ANALYSIS OF THE ALTERNATIVES
Evaluation Criteria
Each remedial alternative was evaluated using the nine criteria established by the National Oil
and Hazardous Substances Contingency Plan. The criteria were derived from the statutory
requirements of CERCLA Section 121 and are listed below:
• Overall protection of human health and the environment
• Compliance with applicable or relevant and appropriate requirements (ARARs)
• Long-term effectiveness and permanence
• Reduction of toxicity, mobility, or volume through treatment
• Short-term effectiveness
• Implementability
• Cost
• State acceptance
• Community acceptance
In selecting the preferred alternative, these nine criteria were used to evaluate the alternatives
developed in the Corrective Measure Study/Feasibility Study for the FRB (U) (WSRC, 1997c).
First seven of the criteria are used to evaluate all the alternatives. The preferred alternative is
further evaluated based on the final two criteria, state acceptance and the community acceptance.
The first two criteria (overall protection of human health and the environment, and compliance
with ARARs) are also categorized as threshold criteria. The next five criteria are categorized as
primary balancing criteria. The last two criteria (state acceptance and community acceptance)
are categorized as modifying criteria.
Detailed Evaluation
The remedial action alternatives discussed in Section VII were evaluated using the nine criteria.
A detailed evaluation of the alternatives is provided in the Feasibility Study (WSRC, 1997c).
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Comparative Analyses
This section discusses how well each alternative addresses the CERCLA evaluation criteria. The
alternatives are discussed in relative order of performance with respect to the particular criterion.
Table 8 provides a summary of the comparative analyses.
Overall Protection of Human Health and the Environment
For soil remedial alternatives, Alternative S5 is the most protective because it involves
stabilizing the waste and providing a cover to minimize stormwater percolation. Alternative S4
is the second most protective because it involves stabilizing the waste source only. Alternative
S3 offers the next best level of protection. Alternative SI, the No Action alternative, offers the
least protection.
For groundwater, both alternatives, Alternative Gl and Alternative G2 are equally protective of
human health and the environment.
For the process sewer line area, Alternative PSA is the most protective of human health and the
environment followed by Alternatives P4 and PI.
Compliance with ARARs
Alternatives SI, S3, S4, S5, PI, P4, and PSA comply with ARARs for soil. Alternative G2
complies with groundwater ARARs.
Long-Term Effectiveness
Of the soil alternatives, Alternative S5 offers the most long-term effectiveness. The second most
effective is Alternative S4, followed by S2, and then Alternative SI (No Action).
Both groundwater alternatives, Alternative Gl and Alternative G2, are equally effective over the
long term for groundwater.
Alternative PSA offers the most protection over the long term for the process sewer line area,
followed by Alternatives P4 and then PI (No Action).
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Table 8. Comparative Analysis Summary
Alternative
SI: No Action
S3: Institutional Controls
and Low Permeability
Cover
S4: Institutional Controls,
and Grouting,
S5: Institutional Controls,
Grouting, and Low
Permeability Cover
(J 1 : No Action
G2: Uroundwater
Monitoring
PI: No Action
P4: Institutional Controls,
Pipeline Grouting, and
Soil Excavation and
Disposition with FRB
Soils
P5A:Excavalion and Ull-
Unil Disposal (SRS
Disposal)
CbkcLA Criterion
Overall Protection or Human
Health of (he Environment
Least1 protective soil alternative
Protective, but not lo (he extent or
S4 or SS
Second most protective soil
alternative
Most protective soil alternative
Equally protective groundwater
alternative
Equally protective groundwater
alternative
Least protective pipeline
alternative
Second most protective pipeline
alternative
Most protective pipeline
alternative
Compliance with ARAKs
Complies with AKAKs
Complies with AKAKs
Complies with AKAKs
Complies with AKAKs
Compliance with
groundwater ARARS can not
be demonstrated
. Complies with groundwater
ARARs
Complies with soil AKAKs
Complies with soil AKAKs
Complies with Soil AKAKs
Long- 1 erm Effectiveness
and Permanence
Least effective soil
alternative In the long term
Effective in the long term,
but not as effective as S4
Second most effective soil
alternative In (he long (erm
Most effective soil
alternative In the long term
Equally effective
groundwater alternative in
the long term
Equally effective
groundwater alternative in
the long term
Least effective pipeline
alternative In the long term
Second most effective
pipeline alternative In the
long term
Most effective pipeline
alternative In the long term
Reduction ol loxicity,
Mobility, or Volume
through Treatment
Does not reduce loiicity,
mobility, or volume
Reduces contaminant
mobility, but not lo (he
extent of S4
Second most effective in
reducing contaminant
mobility for soil •ll:rnallves
Most ellective in reducing
contaminant mobility for
soil alternatives
Does not reduce loxicity,
mobility, or volume
Docs noi reduce loxicity,
mobility, or volume
Does not reduce loxicily,
mobility, or volume
Second most effective in
reducing contaminant
loxicity, mobility, or volume
for pipeline alternatives
Most effective in reducing
contaminant toxlcily,
mobility, or volume for
pipeline alternatives
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Table 8. (Cont'd). Comparative Analysis Summary
Alternative
SI: No Action
S3: Institutional Controls and Low
Permeability Cover
S4: Institutional Controls, and
Grouting
55: Institutional Controls,
Grouting, and Low
Permeability Cover,
Groundwater Monitoring
Gl: No Action
UZ: Uroundwaler Monitoring
PI: No Action
P4: Institutional Controls, Pipeline
Grouting, and Soil Excavation
and Disposition with FRB
Soils
P5A:bxcavalion and Oil-Unit
Disposal (SRS Disposal)
CtRCLA Criterion
Short-Term Effectiveness
Iviost effective soil alternative in ike
short term
Equally effective as S4 and S5 in
the short term
Equally elleclive as S3 and $5 In
the short term
Equally elleclive as S3 and S4 in
(he short term
Equally elTeclive groundwaler
alternative in the short term
Equally effective groundwaler
alternative in the short term
Most effective pipeline alternative
in the short term
Second least effective pipeline
alternative in the short term
Least elfeclive pipeline alternative
in the short term
Implementability
Easiest soil alternative to
implement
Keadily implemented; less
difficult than S4
Second most difficult soil
alternative to implement
Most difficult soil
alternative to Implement
Easiest groundwater
alternative to implement
Easily implemented;
however, more difficult than
Gl
Easiest pipeline alternative
to Implement
Second most difficult
pipeline alternative to
implement
Most difficult pipeline
alternative to implement
Cost
il^,$78
5285,132
SI ,227,694
SI, 460.929
No Cost
511.3,331
19,578
1319,265
$409,134
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Reduction of Toxicity. Mobility, or Volume
No alternative completely reduces toxicity, mobility, and volume at the waste unit. Alternative
S5 ranks the highest in this category for the soil alternatives because it achieves the greatest
reduction in contaminant mobility. Alternatives S4 and S3 also reduce contaminant mobility, but
to a lesser extent than Alternative S5. Alternative SI (No Action) does not affect toxicity.
mobility, or volume.
Alternatives Gl and G2 have no effect on toxicity, mobility or volume.
Alternative PSA, which removes contaminated material from the waste unit, ranks first in this
category for process sewer line area alternatives. Alternative P4 ranks second because it reduces
contaminant mobility. Alternative PI (No Action) has no effect on toxicity, mobility, or volume.
Short-Term Effectiveness
Alternative SI offers the most short-term effectiveness of the soil alternatives. Alternatives S3,
S4, and S5 rank equally in this category as they all provide the same degree of worker exposure
during implementation.
Both groundwater alternatives, Alternative Gl and Alternative G2 are equally effective in the
short term.
Alternative PI is most effective in the short term for the process sewer line area alternatives.
Alternative P4 is moderately effective due to limited remedial worker exposure to contaminants.
Alternative PSA is the least effective alternative due to potential worker exposure to
contaminated material. None of the alternatives should affect the community during remediation.
The site-specific health and safety plan addresses remedial worker risks from equipment
operation for alternatives involving physical activities.
Implementability
Alternatives SI, S3, S4, and S5 are readily implemented; Alternatives S4 and S5 are more
difficult because they will require testing to determine the appropriate grout mixtures.
Alternative Gl is the easiest to implement for groundwater, followed by Alternative G2.
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Alternative PI is the easiest pipeline alternative to implement, followed by Alternative P4.
Alternative PSA is the most difficult to implement.
The No Action alternative, SI, is the least expensive of the soil alternatives (total present worth
cost, $9,578; capital cost $0, and O&M costs, $9,578), followed by Alternatives S3 (total
present worth cost $285,132; capital costs, $266,908; and O&M costs, 5118,224), S4 ( total
present worth cost $1,227,644; capital cost, $1,209470; and O&M costs, $18,224), and S5 (total
present work costs, $1,460,929; capital costs, $1,441,705; and O&M costs, $18,224).
The least expensive groundwater alternative is No Action, Gl (no cost), followed by Alternative
G2 (total present worth cost $1 13,331; capital costs $0; O&M costs, $1 13,331).
The No Action alternative for the process sewer line and pipeline soil, PI, is also the least
expensive in its category ($9,578). Alternative PI is followed by Alternatives P4 (total present
worth cost, 5319,265; capital costs, 5309,687; O&M costs, 59,578) and PSA (total present worth
cost, $409,134; capital costs, $409,134; O&M costs $0).
State and community Acceptance
Alternative SI does not provide short and long-term protectiveness of human health and the
environment and consequently, has not met state and Federal regulatory acceptance. Alternatives
S3 and S4 do provide for reduced containment mobility, however, these alternatives do not
provide a permanent reduction in contaminant mobility and have not met state and Federal
regulatory acceptance. The state and Federal regulatory agencies have accepted and approved
Alternative S5 because it is the least expensive in the long term that provides a most-effective
permanent reduction in contaminant mobility and poses minimal risk to remedial workers and
community. In addition, the Alternative S5 has met the community acceptance.
Both Alternatives Gl and G2 are equally protective of groundwater since no impact to the
groundwater from the operation of the F-Area Basin has been discovered. However, alternative
Gl, in conjunction with institutional controls, will be protective of human health by preventing
the ingestion of groundwater at less cost. Also, groundwater monitoring, which forms an integral
part of the Alternative S5, when implemented in conjunction with Alternative S5, will ensure
that no contaminant leaches out and enter the groundwater after the contaminated soil is grouted
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and thereby, will protect the remedial workers as well as the community. The state and Federal
regulatory agencies have accepted Alternative Gl. In addition, this alternative has met with
community acceptance.
Alternative PI does not provide short and long-term protectiveness of human health and the
environment and consequently, has not met state and Federal regulatory acceptance. Alternative
PSA does provide for the protection of human health by permanent reduction in the contaminant
mobility; however, this alternative is most difficult to implement since this alternative involves
significant waste handling and transport. Consequently, Alternative PSA has not met state ar.d
Federal acceptance or community acceptance.
The state and Federal regulatory agencies have accepted and approved Alternative P4. This
alternative when implemented in conjunction with Alternative S5, will provide a permanent
reduction in contaminant mobility, pose minimal risk to the remedial workers and the
community, and is the least expensive alternative. In addition, the alternative has met the
community acceptance.
IX. THE SELECTED REMEDY
The selected remedies for the FRB OU are: (1) for the basin soils: Alternative S5: Institutional
Controls, Grouting, a Low Permeability Cover, and Groundwater Monitoring; (2) for the former
process sewer line: Alternative P4: Institutional Controls, Pipeline Grouting, Soil Excavation
and Disposition in the Basin Soils, and; (3) for the groundwater: Alternative Gl: No Action. The
waste unit will be physically maintained and institutional controls will remain in place in
perpetuity. Field conditions will be evaluated to determine the need for modifying the control
program or to identify if further remedial action is appropriate during the five-year ROD review.
Since each remedy requires institutional controls, these controls are discussed here instead in the
more detailed description of each selected remedies provided below. Implementation of
institutional controls will involve both short- and long-term actions. For the short-term action,
signs will be posted at the FRB OU indicating that this area was used for the disposal of waste
material and contains buried waste. Additionally, existing SRS access controls will be used to
maintain 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 take those actions necessary
pursuant to Section 120(h) of CERCLA. These actions will include a deed notification
disclosing former waste management and disposal activities as well as any remedial actions
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taken on the site and any continuing groundwater monitoring commitments. These requirements
are also consistent with the intent of the RCRA deed notification required at final closure of the
RCRA facility if contamination would remain at the unit. 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 deed
restrictions may be reevaluated at the time of transfer in the event that contamination no longer
poses an unacceptable risk under residential use. Any revaluation of the need for deed
restrictions would be done through an amended ROD with the Environmental Protection Agency
(EPA) and the South Carolina Department of Health and Environmental Control (SCDHEC)
approval. In addition, a certified survey of the area will be prepared by a registered land
surveyor and will be included in the post-ROD documents. The survey will be reviewed and
updated, as necessary, at the time the site is transferred and will be recorded with the appropriate
county recording agency. The FRB OU is located in Aiken County.
Per the EPA-Region IV Land Use Controls (LUCs) Policy, a Land Use Control Assurance Plan
(LUCAP) and a Land Use Control Implementation Plan (LUCIP) will be developed and
submitted to the regulators for their approval. The LUCAP will be submitted under separate
cover whereas the LUCIP will be submitted with the Remedial Work Plan/Remedial Design
Report/Remedial Action Work Plan (RDWP/RDR/RAWP) for the FRB OU in accordance with
the post-ROD document schedule is provided in Figure 16. The LUCAP will include the
information requested in the EPA policy. The LUCIP details how SRS will implement,
maintain, and monitor the land use control elements of the FRB OU ROD to insure that the
remedy remains protective of human health.
The LUC objective necessary to ensure the protectiveness of the preferred alternative is:
Prevent unauthorized access/exposure to contaminated grout and basin soil
The institutional controls required to prevent unauthorized exposure to the contaminated grout
and soil include the following:
• Controlled access to the FRB waste unit through existing SRS security gates and perimeter fences
and the site use/site clearance programs
• Signs posted in the area to indicate that contaminated grout and soil are present in the waste
unit
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• Notification of contaminated grout and soil to any future landowner through deed
notification, as required under CERCLA Section 120(h)
The present worth, capital, and Operation and Maintenance (O&M) costs for each selected
remedy is provided Table 9.
Table 9. Selected Remedy Cost
Remedy
Alternative J^* (Soils)
Alternative P4 (Process
Sewer)
Alternative Ul*
(Groundwater)
Total Cost
Present worth
Cost
$1,461,000
$320,000
No Cost
$1,781,000
Capital Cost
i 1,442,000
S3 10,000
No Cost
$1,752,000
U&M Cost
iiy.ooo
510,000
No Cost
$2y,ooo
* Alternative S5 includes the costs for groundwater monitoring.
The selected remedy will meet all of the RAOs by eliminating the potential for direct radiation,
exposure, ingestion of soils, and eliminating future impacts to groundwater. The selected
remedies comply with all applicable or relevant and appropriate Federal and state
requirements/regulations.
The SCDHEC has modified the SRS RCRA permit to incorporate the selected remedies.
Soils
Under the selected remedy (Alternative S5), deep basin soil will be grouted from approximately
0.6 m (2 ft) above the basin bottom to approximately 1.8 m (6 ft) below the basin bottom or
approximately 4.3m (14 ft.) below grade. The purpose of the grout is to prevent leaching of Sr-
90, which is the only contaminant migration COC (CMCOC), to the groundwater above the
MCL of 8.0 pCi/L. Furthermore, grouting the soil provides an additional layer of protection by
offsetting the inherent uncertainty associated with the mathematical model used to predict
contaminant migration. Grouting will also immobilize other deep contaminants which represent
principal threat source material such as Cs-137, Ra-226, thallium, arsenic., etc and further reduce
infiltration of water through the deeper contaminated soils. Tc-99 was originally identified in the
RFI/RI/BRA as a CMCOC. Subsequent evaluation with the RESRAD model eliminated it as a
concern. However, as is the case with other radioactive/non-radioactive contaminants, the
selected remedy will also immobilize Tc-99. Grouting of the soils is preferred over only capping
because it meets the CERCLA preference for treatment. A cover will be provided over the
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stabilized soil to minimize storm water percolation and erosion. The cover is also very effective
in reducing direct radiation exposure received from radionuclides in the shallow soil. This
alternative includes institutional controls (discussed above) to prevent exposure of current and
future workers to all the Human Health COCs in the waste unit and direct radiation from the
waste unit. Since waste is left in place, the future use of land will be restricted to industrial use
to prevent unrestricted residential use of the land.
In situ grouting reduces air emissions and is relatively simple to implement. However, in situ
grouting results in a slight increase in waste volume. The volume of the basin, when clean soil is
excavated prior to grouting, will be adequate to accommodate any increase in grouted soil
volume. The estimate volume of grout/soil mixture is 6,600 m3 (8,100 yd3)..
Process Sewer Line
The selected remedy for the process sewer line and associated soils will include pipeline and
manhole grouting, and excavation and disposition of pipeline soils (approximate volume 240 m3
or 300 yd 3) into the basin and institutional controls. In this alternative, the localized areas of the
contaminated soil around the pipeline hot spots will be excavated. If necessary, the sections of
pipeline associated with the hot spots will also be excavated. The excavated soil and pipeline
will be treated in the basin by in situ grouting along with soil from the basin. Clean soil from
SRS borrow areas will be used to fill excavated areas around the pipeline. Completion of this
remedial action will meet all applicable or relevant and appropriate Federal and state
requirements/regulations, and all the remedial action objectives by reducing risk associated with
the process sewer line to acceptable levels. This alternative includes institutional controls
(discussed above) to prevent exposure of current and future workers to all the Human Health
COCs in the waste unit and direct radiation from the waste unit. Since waste is left in place, the
future use of land will be restricted to industrial use to prevent unrestricted residential use of the
land.
Groundwater
The selected remedy for the FRB OU groundwater is "No Action". The history of the FRB, the
results of the groundwater modeling, and the current groundwater data prove that the FRB-
associated groundwater poses no risk to human health or the environment. Through computer
modeling and sampling it has been shown the FRB OU has not contributed to contamination in
the groundwater. However, to ensure that the grout-waste mixture has accomplished the required
immobility of contamination, a groundwater-monitoring program will be established under the
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selected remedy for basin soils (Alternative S5). The groundwater will be monitored semi-
annually until it is confirmed that the remedial response action for the FRB OU has achieved the
required stabilization of the contaminants.
Since waste is left in place in the FRB waste unit, the future use of land will be restricted to
industrial use to prevent unrestricted residential use of the land and five-year ROD reviews will
be required.
X. STATUTORY DETERMINATIONS
Based on the RI/BRA report, the FRB OU poses future risks and hazards to the on-unit resident,
construction worker, and industrial worker. The future risks are associated with: external
exposure to COC radionuclides by direct contact into the FRB OU soils; potential exposure to
principal threat source material; ingestion of FRB OU soils and pipeline sediment and/or produce
grown in soils contaminated with radionuclides; and ingestion of groundwater containing Sr-90
(which can leach out and migrate to groundwater) with concentrations above MCL. Therefore,
institutional controls, in situ grouting of soils, and installation of a low permeability cover over
the grouted soils in the basin are necessary for the former basin area soils. Institutional controls,
pipeline grouting, excavation, and disposal of pipeline associated soils with basin area soils are
necessary for the process sewer line area. No action is required for the groundwater; however,
groundwater shall be monitored to confirm that the source remediation has achieved the required
stabilization of contaminants. The grouting (using S/S treatment) will reduce the mobility of the
radionuclides (the principal threat source material), thereby preventing migration of
radionuclides to the groundwater. The soil cover provided over the grouted soil will shield
radiation exposure from the radionuclides contained in the grouted soil in the basin and also
prevent ingestion of soil and/or produce grown in FRB OU soils.
The selected remedy is protective of human health and the environment, complies with federal
and state ARARs, and is cost-effective. The ARARs are met by minimizing the potential for
contaminant migration into the groundwater by stabilizing the soil into a nonleachable form.
(The size and location of the waste unit radioactive contaminants preclude a remedy in which
contaminants could be excavated and treated effectively). For cost comparison among the
considered alternatives and to determine the most cost-effective alternatives, cost estimates
prepared for the alternatives were based on a variety of cost estimations data, including generic
unit costs, vendor information, and prior similar estimates prepared for other SRS sites with
almost identical characteristics. Cost estimates were prepared for capital costs, O&M costs, and
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present worth costs. Finally, for selecting the cost-effective.remedial action for the FRB OU. an
analysis was performed by considering the following factors:
• the effective life of the remedial action
• the uncertainty regarding some of the COCs, especially radionuclides that could stay
absorbed in the contaminated soil for over 1,000 years and could pose a future long-term
unacceptable risk even beyond 100 to 200 years
• the preference for treatment versus containment per CERCLA requirements, and
• long-term versus short-term in situ management of radioactive wastes
Based on the analysis, the selected remedial action was determined as a cost-effective measure
that would provide a permanent reduction of contaminant mobility, meet the statutory
requirements of CERCLA, ensure future compliance with ARARs (MCLs or RBCs), and present
a reasonable value for the protection of human health and the environment.
Contaminated soils represent principal threat source material and will be stabilized to prevent or
mitigate exposure to highly toxic contaminants and permanently reduce mobility of highly
mobile contaminants at depth. The selected remedy utilizes long-term permanent solutions and
treatment technology to the maximum extent practicable and satisfies the preference for
treatment.
Since soil and pipeline sediment is grouted below grade, long-term weathering and the potential
for leaching of contaminants are minimized. Worker and public safety is ensured by minimizing
contact with contaminated media.
Section 300.430 (f) (4) (ii) of the NCP requires that a five-year review of the ROD be performed
if hazardous substances, pollutants, or contamination remain in the waste unit. The three parties
(DOE, SCDHEC, and EPA) have determined that a five-year review of the ROD for the FRB OU
will be performed to ensure continued protection of human health and the environment.
XI. EXPLANATION OF SIGNIFICANT CHANGES
A public comment and CAB recommendation were received on the Statement of Basis/Proposed
Plan; raising a concern regarding the need to grout the soil in addition to capping the basin soil.
A response to the concern is included in the Responsiveness Summary (Appendix A of this
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document). No significant changes were made as a result of public comment. The selected
alternatives from the Statement of Basis/Proposed Plan remain the selected remedial action.
XII. RESPONSIVENESS SUMMARY
The Responsiveness Summary is provided as Appendix A of this document.
XIII. POST-ROD DOCUMENTS SCHEDULE AND DESCRIPTION
1. The Post-ROD documents schedule is listed below and is illustrated in Figure 20.
2. Corrective Measures Implementation/Remedial Design Work Plan (CMI/RDWP),
Revision 0, for the FRB OU will be submitted for EPA and SCDHEC review 2
calendar days after issuance of the ROD.
3. SRS revision of the CM/RDWP will be completed 30 calendar days after receipt of
all regulatory comments.
4. Corrective Measures Implementation/Remedial Design Report/Remedial Action
Work Plan (CMI/RDR/RAWP), Revision 0, will be submitted 75 calendar days after
issuance of the ROD.
5. SRS revision of the CMI/RDR/RAWP will be completed 45 calendar days after
receipt of all regulatory comments.
6. Remedial Action Start on the soils will begin following EPA and SCDHEC approval
of the CMI/RDR/RAWP.
7. Post-Construction Report (PCR), Revision 0, will be submitted to EPA and SCDHEC
after completion of the remedial action.
Post-ROD Document Description
A brief description of the post-ROD documents is provided. Corrective Measures
Implementation/Remedial Design Work plan (CMI/RDWP)
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Figure 20. FRB Post-ROD Document Schedule
ACTIVITY
EARI.V EARLY ORIO
START FINISH OUR
RECORD OF DECISION
EPA/SCPHKC ROD ISSUANCE
2RSF.P9S 0
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EPA/SCDHEC REVtEM REV 0 ROMP
SRS INCORPORATE EPA/SCDHEC COMMENTS
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SRI SUBM1TTAL OP REV. '0 CM/RDR/AAMP
EPA/SCDMCC HBVXEM OF REV. 0
RCR/RAWP
SAft INCORPORATE EPA/SCDIIEC COMMENTS
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Based on the data and information contained in the previous documents pertaining to FRB OU
(including RI/BRA Report, Corrective Measures Study/Feasibility Study, Statement of
Basis/Proposed Plan, and Record of Decision), CMI/RDWP will provide a description of the
remedial action design for the FRB OU.
The remedial action design discussed in CMI/RDWP would include a basic scope description of
the following tasks that will be performed during the remedial design:
• Topographic survey and preparation of site drawings
• Preparation of erosion control plan
• Development of acceptance criteria for the S/S process, and preparation of construction
specifications for S/S activities
• Preparation of statement of work for final soil matrix design
• Design of the soil cover system
• Determination of institutional controls for the basin and process sewer line
• Schedule for developing the LUCIP under EPA Region IV policy on Land use Controls
at Federal Facilities
• Preparation of groundwater monitoring plan
• Preparation of health and safety and cover system maintenance plans
Corrective Measures Implementation/Remedial Design Report/Remedial Action Work Plan
(CMI/RDR/RAWP)
This document will combine the contents and purposes of the two post-ROD documents: the
Corrective Measures Implementation/Remedial Design Report (CMI/RDR) and the Corrective
Measures Implementation/Remedial Action Work Plan (CMI/RAWP). This combined document
will primarily outline and describe the remedial design and remedial action planned for the FRB
OU and will address:
1. a remedial design summary highlighting the critical design inputs and outputs that are
consistent with the remedial action objectives stated in the ROD; and
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2. construction strategy summary highlighting the critical components of the construction
phase, including the remedial action schedule, a design change procedure, requirements of
health and safety aspects driving the construction phase and project closeout. The current
schedule for completing post-ROD documents and RA start may require a phased approach
to the completion of this document (e.g., validation of soil solidification mix design not
completed until after RA start). This document will also include a brief discussion on the
contents of the post-construction report. The CMI/RDR/RAWP will primarily include:
• Site drawings showing the boundaries of the basin and locations of process sewer lines
and manholes, etc.
• Design Criteria including performance criteria and acceptance activities for S/S remedial
action
• Design plans and specifications
• Permitting requirements
• Post-documentation identification and schedule to accommodate phased RA approach
• Erosion control plan
• Groundwater monitoring well maintenance plan
• Land Use Controls Implementation Plan (LUCIP)
• Remedial action schedule and remedial design change control
• Waste management plan, including decontamination requirements
• Health and safety plan
• Maintenance plan, including institutional control requirements
• Requirement for project closeout
• Post-construction report description
XIV. REFERENCES
CFR 1991 Reference: Code of Federal Regulations. National Primary Drinking Water
Regulations, 40 CFR, Part 141, pp. 578-715. Washington, DC.
EPA, 1988. Guidance for conducting Remedial Investigations and Feasibility Studies under
CERCLA, EPA/S40/G-89/004, Washington, DC (1988).
EPA, 1989a. Risk Assessment Guidance for Superfund (RAGS). Volume I: Human Health
Evaluation Manual (Part A), Office of Emergency and Remedial Response, USEPA/540/1-
89/002, Washington, DC (1989).
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EPA, 1989b. Risk Assessment Guidance for Superfund (RAGS). Volume II: Environmental
Evaluation Manual, Office of Emergency and Remedial Response, USEPA/540/1-89/001.
Washington, DC (1989).
EPA, 1998, Assessing Land Use Controls at Federal Facilities, a memorandum issued by EPA
Federal Facilities Branch, 4WD-FFB, dated April 21,1998.
FFA, 1993, Federal Facility Agreement for the Savannah River Site, Administrative Docket
Number 89-05-FF, Effective Date: August 16, 1993, WSRC-05-94-42
WSRC, 1993b. RCRA Facility Investigation/Remedial Investigation Program Plan, Revision 1,
WSRC-RP-89-994, Savannah River Site, Aiken, SC (1993).
DOE, 1994a. Public Involvement. A Plan for the Savannah River Site, Savannah River
Operations Office, Aiken, SC (1994).
WSRC, 1994b. Phase II Remedial Investigation Work Plan for the F-Area Retention Basin
(281-3F) (U), WSRC RP-94-498, Savannah River Site, Aiken, SC (May 1994).
WSRC, 1994c. Report on the Robotics Investigation of the F-Area Retention Basin (281-3F)
Process Sewer Pipeline (U). Revision 0, WSRC-RP-94-1105, Savannah River Site, Aiken, SC
(September 1994).
EPA, 1995. Region IV. Supplemental Guidance to RAGS: Region IVBulletins. Ecological Risk
Assessment (November 1995).
WSRC, 1996. Laboratory-Scale Immobilization Study Report for the L-Area Oil and Chemical
Basin, WSRC-RP-95-15, Rev. 0, Savannah River Site, Aiken, SC
WSRC, 1997a. Ground-water Sampling Report with Residential Risk Assessment for the F-Area
Retention Basin (28I-3F) (U), WSRC-RP-96-00905, Revision 0, March 1997.Savannah River
Site, Aiken, SC
WSRC, 1997b. Remedial Investigation with the Baseline Risk Assessment Report for the F-Area
Retention Basin (281-3F) (U), WSRC-RP-96-356, Revision 1.2, Savannah River Site, Aiken,
SC.
WSRC, 1997c. Corrective Measures Study/Feasibility Study for the F-Area Retention Basin
(281-3F) (U). WSRC-RP-96-00906, Revision 1.2, Savannah River Site, Aiken, SC (November
1997).
WSRC, 1997d. Statement of Basis/Proposed Plan for the F-Area Retention Basin (28J-3F) (U).
WSRC-RP-97-00128, Revision 1.2, Savannah R:ver Site, Aiken, SC (November 1997).
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APPENDIX A
RESPONSIVENESS SUMMARY
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Responsiveness Summary
The 45-day public comment period for the Statement of Basis/Proposed Plan (SB/PP) for the F-
Area Retention Basin (281-3F) began on January 20, 1998, and ended on March 5, 1998. SRS
briefed the public on the path forward for the remediation of the basin in a Citizens Advisory
Board (CAB) subcommittee meeting held on February 23, 1998. At the meeting, a concern was
raised over the need to grout the soil in addition to providing a low permeability cap over the
basin area. Subsequently, an extension for the public comment period was granted extending the
public comment period to April 4,1998. A formal public comment (made by Todd V. Crawford)
was received which questioned the risk reduction and necessity of the soil grouting. A formal
CAB recommendation (see attached Recommendation No. 56) was also received on March
28,1998. A response to these concerns is provided below. The public and CAB comments are
italicized and the response is bolded.
Public Comment:
The Remedial Action Objectives are stated as:
Prevent future ingestion of shallow aquifer groundwater
Prevent direct contact with and ingestion of soils
Prevent direct contact with and ingestion of sediments from the abandoned process sewer
line
Prevent the transport of contaminants from subsurface soils to groundwater
The first three of the above are met now and would be met in the future considering that
institutional controls are part of all alternatives and land use plans clearly put the F-Area
Retention Basin and associated pipelines in an industrial area.
The first of the Remedial Action Objectives above removes the concern about the last one. On
top of that there is other contamination in the shallow groundwater in the vicinity which would
negate interest in drinking the water.
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The scenarios upon which the risk numbers are based are not stated in enough detail to evaluate.
They must have been based on direct exposure to the contaminated soils, which are nou under
about 10 feet of clean dirt. Such direct exposure could not happen unless institutional controls
were lost for the 200-Area plateau. If this happens the F-Area Retention Basin would be a minor
problem compared to other locations in the 200-Area. If loss ^f institutional controls was
assumed, the risk numbers would sure be misleading to the public.
Contaminates of concern include Arsenic. It is not clear if this came from the F-Area processes
or is a result of early cotton farming. Or is the Arsenic and the Radium-226 from coal pile
runoff? Is the K-40 from the processes or is it the naturally occurring K-40? Additionally,
evaluation of the risk reduction as a function of the various alternatives for remedial action is not
included. It appears that the main justification for the grouting of the basin soil under Alternative
S5 is to reduce leaching but perhaps a cap on top of the current clean fill would be sufficient.
The primary contaminate of concern for leaching is Sr-90 with a 28.6 year half life so caps may
well make significant difference in concentrations reaching the groundwater. How much
remediation is justified when nobody will be drinking the water?
CAB Recommendation:
Because the F-Area Retention Basin and associated pipelines are in the nuclear industrial area
and will be under institutional controls followed by deed restrictions, and because this site has
been buried for 20 years with no identified contaminant migration, the SRS Citizens Advisory-
Board believes that the Remedial Action Objectives can be met with less extensive remediation.
CAB recommends a low-permeability cap for the basin, continued groundwater monitoring and
grouting the inside of the pipeline. These changes should reduce the total remediation costs by
about $1 million.
Response:
A risk assessment for the F-Area Retention Basin Source Operable Unit (FRB OU) was
performed in accordance with CERCLA guidance. The relative risk values for the FRB OU
indicate that remediation is required per the statutory requirements of CERCLA. Both the
former basin and process sewer line areas represent a risk to a future on-unit resident as well as
to a future industrial worker. Radionuclides including cesium-137, radium-226, actinium-228,
and strontium-90 are the primary risk drivers for the direct radiation pathways and represent over
90 percent of the risk. These contaminants also present a future long-term groundwater risk
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resulting from their leaching out from the soil and entering the groundwater at levels above
applicable state regulations(i.e., MCLs).
Since the FRB OU poses unacceptable risk and a remedial action is appropriate, a Corrective
Measures Study/Feasibility Study (CMS/FS) was performed to identify appropriate remedial
alternatives. The alternatives were selected and screened in accordance with CERCLA guidance
and a detailed analysis of the selected alternatives was performed using the nine evaluation
criteria as required by the NCP. Alternative S5: Institutional Controls, Grouting, Low
Permeability Cover, and Groundwater Monitoring was selected because it would provide a
permanent reduction in contaminants (radionuclides) mobility and prevent contact with and
ingestion of contaminated soil. To ensure the effectiveness of this alternative, groundwater
monitoring downgradient of the grouted mass is also included in this alternative. This alternative
is also very effective in reducing potential direct radiation exposure received from radionuclides
and grouting the soil also provides an additional layer of protection by offsetting the inherent
uncertainty associated with the mathematical model used to predict contaminant migration. EPA
and SCDHEC approved both the CMS/FS and the SB/PP documents that justified the selected
remedy. The selected remedy provides the best alternative because it meets EPA preference for
treatment versus containment per CERCLA requirements and provides an additional layer of
protection.
The quantifiable reduction of baseline risk is an essential consideration in remedy selection. All
remedial alternative evaluations analyze the risk remaining after remediation. This is done
through the setting of risk-based remediation goal options (RGOs). Not all cleanup objectives,
however, are risk-based. The National Contingency Plan includes a preference for treatment of
principal threat wastes. Therefore, to determine the future risk posed by the radionuclides
(principal threat wastes) the risk-based modeling was performed during the development of the
Remedial Investigation/Baseline Risk Assessment (RI/BRA) report for the FRB OU. It was
determined that some of the contaminants of concern (COCs), especially radionuclides, could
stay absorbed in the contaminated soil for over 1000 years and could pose a future long-term
unacceptable risk even beyond 100 to 200 years. The selected remedy (Alternative S5)
incorporates this preference as a key element of the prudent long-term management of
radioactive waste in situ.
The soil cover provided over the former basin area and contaminated soil associated with the
process sewer line area, without grouting the soil, could provide a permanent long-term solution
by simply containing the contaminants if well maintained for an extended period of time.
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However, in terms of total remediation cost, the soil cover would cost less initially but would
likely need redesign/reconstruction two or three times during the entire remediation cycle, which
could go beyond 100/200 years. In the long term, the cost of the soil cover would approximate
the cost of the selected remedy. Hence, in situ grouting coupled with a low permeability cover
was determined to be the best alternative that would provide permanent reduction of contaminant
mobility, meet the statutory requirements of CERCLA, and also ensure future compliance with
applicable state regulations (i.e., MCLs).
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Savannah River Site Citizens Advisory Board
Recommendation No. 56
March 24,1998
Remediation of F-Area Retention Basin
Background:
The F-Area Retention Basin is an unlined basin 120 by 200 feet, which collected lightly
contaminated cooling water from the F-Area Canyon Facility as well as stormwater drainage
from the F-Area Tank Farm. The basin was used from 1955 to 1972. In 1978, its soil was
sampled and analyzed, contaminated soil removed, and the basin closed. Closure consisted of
filling the basin with about 7 to 10 feet of clean dirt and seeding the surface with grass.
Numerous environmental investigations were completed on the retention basin and the
connecting process sewer line between 1993 and 1997. Extensive sampling data and analyses
were published along with pathway and risk calculations.1 The most significant contaminates are
Arsenic and Cesium-137. Also, fate and transport analyses have indicated that levels of certain
radionuclides (e.g., lechnetium, strontium) could exceed acceptable concentrations in the
groundwater under the basin. The risk analyses, under conservative assumptions, indicate a risk
above the CERCLA guidelines only for an onsite resident exposed to the remaining
contaminated soils in the basin. However, there is currently no risk to onsite workers or the
offsite public. Further, this site is located in an industrial cleanup zone (see Motion 2).
Remedial Action Objectives for an onsite resident have been identified and remediation
alternative have been evaluated.2 These Remedial Action Objectives are: prevent future
ingestion of shallow aquifer groundwater; prevent direct contact with and ingestion of soils
(basin and pipeline); prevent direct contact with and ingestion of sediments from the abandoned
process sewer line; and prevent the transport of contaminants from subsurface soils to
groundwater (basin and pipeline). Remedial alternatives were evaluated for basin soils (4
alternatives), for groundwater (2 alternatives) and process sewer line and pipeline soils (3
alternatives). <2J) All alternatives require institutional control and the recording of basin and
pipeline locations as deed restrictions before releasing the land to the public. The preferred
1 Remedial Investigation Report with the Baseline Risk Assessment for the F-Area Retention Basin (281-3F), final,
WSRC-RP-96-356, Rev. 1.2, July 1997
1 Corrective Measures Study/Feasibility Study for the F-Area Retention Basin (281-3F), Final, WSRC-RP-96-
00906, Rev. 1.2, November 1997
J Statement of Basis/Proposed Plan for the F-Area Retention Basin (281-3F). Final, WSRC-RP-97-00128, Rev. 1.2,
November 1997
I02(*r»p doc JSB/blb 09/22/91
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ROD for the F-Area Retention Basin (281-3F) WSRC-RP-97-145
Savannah River Site Revision 1.1
August 1998 Page 7 of 7
alternatives are: for the basin soils - institutional controls, grouting and low permeability cover
(51,460,929); for groundwater - no action (S9.578); and for the process sewer line and pipeline
soils - institutional controls, pipeline grouting and soil excavation and disposition with the basin
soils (5319,265). The reduction in risk was not evaluated quantitatively for any of these
alternatives; however, the relative risk reductions were evaluated qualitatively.
Recommendation:
Because the F-Area Retention Basin and associated pipelines are in the nuclear industrial area
and will be under institutional controls followed by deed restrictions, and because this site has
been buried for 20 years with no identified contaminant migration, the SRS Citizens Advisory
Board believes that the Remedial Action Objectives can be met with less extensive remediation.
We recommend a low-permeability cap for the basin, continued groundwater monitoring and
grouting the inside of the pipeline. These changes should reduce the total remediation costs by
about $1 million.
Because the amount of risk reduction for different remediation alternatives is critical in the
selection of cost effective remediation strategies, the SRS Citizens Advisory Board recommends
that in the future that all SRS remediation studies include analyses of the risk remaining after
remediation for the most likely alternative and the most probable pathway and exposure
scenarios.
Furthermore, the extensive analyses and documentation for the F-Area Retention Basin and
associated pipeline probably cost as much or more than the planned remediation. This leads us
to make the more general recommendation that the three agencies (DOE, EPA and SCDHEC)
expeditiously implement the Plug-In-ROD approach to reduce future paperwork costs.
102«crwp doc JSB/blb 09/12/91
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