Superfund Record of Decision Savannah River Site (USDOE) OU11 Central Shops Burning / Rubble Pit (631-6g) (u) Aiken SC


                                    EPA/ROD/R04-97/207
                                    1997
EPA Superfund
     Record of Decision:
     SAVANNAH RIVER SITE (USDOE)
     EPA ID: SC1890008989
     OU11
     AIKEN, SC
     05/14/1997

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                                   Printed in  the United States of America
                                                 Prepared for
                                          U.S. Department of Energy
                                                      and
                                     Westinghouse Savannah River Company
                                            Aiken, South Carolina
                                              RECORD OF DECISION
                                        REMEDIAL ALTERNATIVE SELECTION
                            FOR THE CENTRAL SHOPS BURNING/RUBBLE PIT  (631-6G)  (U)
                                                WSRC-RP-96-873
                                                  Revision 1
                                                  April 1997
                                             Savannah River Site
                                            Aiken, South Carolina
                                                 Prepared by:

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

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DECLARATION FOR THE RECORD OF DECISION

Unit Name and Location

Central Shops Burning/Rubble Pit (631-6G)
Savann2h River Site
Aiken, South Carolina

The Central Shops Burning/Rubble Pit (631-6G) (BRP6G) 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).

Statement of Basis and Purpose

This decision document presents the selected remedial alternative for the BRP6G located at the
SRS in Aiken, South Carolina. The selected alternative was developed in accordance with CERCLA,
as amended, and to the extent practicable, the National Oil and Hazardous Substances Pollution
Contingency Plan (NCP). This decision is based on the Administrative Record File for this
specific RCRA/CERCLA unit.

Description of the Selected Remedy

The selected remedy for BRP6G is No Action. Other remedial alternatives for this unit were not
considered because the risk levels fall within the risk range designated as reguiring a risk
management decision for all potential future receptors. The risk levels were developed in the
Baseline Risk Assessment (BRA) , which considered both the future residential and future
industrial use scenarios. The cumulative soil related risks for the future residential land use
scenario are less than one excess cancer in one hundred thousand (1 x 10 -5). In the future
industrial land use scenario, all of the soil related risks are below 1 x 10 -6. The expected
future use of this area is industrial. The South Carolina Department of Health and
Environmental control has modified the SRS RCRA permit to incorporate the selected remedy.

In the future residential land use scenario, the contaminants that contributed to the risk were
arsenic, beryllium, iron, octachlorodibenzo-p-dioxin (OCDD), and polychlorinated biphenyl (PCB)
1254. Of these the concentrations of arsenic, beryllium, iron, and OCDD were not significantly
elevated with respect to unit-specific background levels. The only risk directly attributable
to the pit soil is 2 x 10 -6 due to PCB-1254 via ingestion of produce grown on-site. The
maximum concentration of PCB-1254 detected in the pit was 0.115 mg/kg, approximately 10% of the
residential action level for PCBs of 1 mg/kg (EPA, 1990). Drinking water standards for
groundwater were exceeded in one well, on one occasion, for two compounds. Since these results
were not reproducible in subseguent sampling, the exceedances are considered to be atypical and
not unit related. Therefore, no action is appropriate.

If the property is ever transferred to non-federal ownership, the U.S. Government will create a
deed for the new property owner which will contain information in compliance with CERCLA 120
(h). The deed shall include notification disclosing former waste management and disposal
activities as well as remedial actions taken at the site. The deed notification shall, in
perpetuity, notify any potential purchaser that the property has been used for the management
and disposal of construction debris and other materials, including hazardous substances. In
addition, if the site is ever transferred to non-federal ownership, a survey plat of the area
will be prepared, certified by a professional land surveyor, and recorded with the appropriate
county agency.

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Statutory Determination

Based on the BRP6G Resource Conservation and Recovery Act (RCRA)  Facility Investigation/Remedial
Investigation (RFI/RI)  Report and the Baseline Risk Assessment,  the BRP6G poses no significant
risk to the environment and to human health.  It is, therefore,  proposed that No Action be
performed for the BRP6G.  Me selected remedy is protective of human health and the environment
and complies with Federal and state reguirements that are legally applicable or relevant and
appropriate to the remedial action.

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                                               DECISION SUMMARY
                                               TABIiE OF CONTENTS
Section

Declaration for the Record Of Decision 	i

I.      Site And Operable Unit Name,  Location,  And Description 	1
II.     Operable Unit History And Compliance History 	1
III.    Highlights Of Community Participation 	4
IV.     Scope And Role Of Operable Unit Within The Site Strategy 	5
V.      Summary Of Operable Unit Characteristics 	5
VI.     Summary Of Operable Unit Risks 	14
VII.    The Selected Remedy 	22
VIII. Statutory Determinations 	22
IX.     Explanation Of Significant Changes 	22
X.      Responsiveness Summary 	22
XI.     References 	23

Appendix A 	24

Responsiveness Summary 	25


                                                List of  Figures

Figure 1      Location of BRP6G at the Savannah River  Site 	2
Figure 2      Location of BRP6G in the Central Shops Area of SRS 	3
Figure 3      Potentiometric Surface of the Water Table  (Aquifer Unit IIB)
              at the BRP6G 	7
Figure 4      Complete Characterization of the 1994 BRP6G Sampling Plan 	8
Figure 5      Conceptual Site Model  for Soil Risks for Current Groundwater Sampler
              and Current Material Yard Worker 	16
Figure 6      Conceptual Site Model  for Soil Risks for Hypothetical Future Industrial
              Workers 	17
Figure 7      Conceptual Site Model  for Soil Risks for Hypothetical Future Residents,
              Adult and Child Only 	18


                                                List  of  Tables

Table 1       Analytes and COPCs  in Surface Soil (0-2  ft)  Used in Calculations  of
              Risk & Hazard 	10
Table 2       Analytes and COPCs  in Shallow Subsurface Soil (0-5 ft)  Used in
              Calculations of Risk & Hazard 	10
Table 3       Average Soil Concentrations of SSCs and  COPCs Compared to Soil Screening
              Levels 	11
Page

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1. SITE AND OPERABIiE UNIT NAME, LOCATION, AND DESCRIPTION

SRS occupies approximately 800 square kilometers (310 square miles) of land adjacent to
the Savannah River, principally in Aiken and Barnwell counties of South Carolina. SRS is a
secured U.S. Government facility with no permanent residents. SRS is located approximately 40
kilometers (25 miles) southeast of Auqusta, Georqia and 32 kilometers (20 miles)
south of Aiken, South Carolina.

SRS is owned by the U.S. Department of Enerqy (DOE). Manaqement and operatinq services are
provided by Westinqhouse Savannah River Company (WSRC). SRS has historically produced tritium,
plutonium, and other special nuclear materials for national defense.

BRP6G is located in the Central Shops Area near the center of the SRS (Fiqure 1). Fiqure 2
shows the relative location of BRP6G with respect to Central Shops Area facilities. The BRP6G
Solid Waste Manaqement Unit is on the southeastern side of a divide that separates the drainaqe
basins of the Pen Branch Creek [approximately 1.6 km (1 mile) to the southeast] and Four mile
Branch [approximately 4 km (2.5 mile) to the northwest]. The qround elevation is approximately
88.4m (290 feet) above mean sea level. Surface drainaqe is southward to an unnamed tributary of
Pen Branch.

II. OPERABLE UNIT HISTORY AND COMPLIANCE HISTORY

Operable Unit History

The BRP6G operated from 1951 throuqh 1955 for the disposal and burninq of waste materials. The
unit consisted of a shallow unlined excavation, approximately 3 m (10 ft) deep. Historical
records indicated that the disposal area at the BRP6G was approximately 83.8 m (275 ft) lonq and
9.1 m (30ft) wide. A qround penetratinq radar survey indicated that most of the soil in this
area was undisturbed. This survey detected two areas of disturbed soil which could have been
disposal sites. The larqest area (Zone 1) is rectanqular in shape and is approximately 6.1 m
(20 ft) wide by 54.86 m (180 ft) lonq. A second area of disturbed soil (Zone 2) forms an
ellipse approximately 6.1 m (20 ft) wide by 12.2 m (40 ft) lonq. The GPR survey did not find
buried waste within the smaller disturbed soil area. This smaller disturbed soil area was
likely a borrow pit used to provide waste cover.

Materials believed to be disposed of in the pit included waste oils, raqs, paper, cardboard,
plastics, deqreasers, wood, rubber, and drummed orqanic solvents. These materials were
periodically burned in the pit, usually on a monthly basis. The volume of waste disposed of at
BRP6G was not recorded. The materials burned in the burninq/rubble pit included potentially
hazardous substances, such as orqanic solvents. In 1955 after disposal activities ceased, the
area was covered with soil. Due to the potential that hazardous substances, which if present,
could have miqrated into the surroundinq soil and/or qroundwater, BRP6G was desiqnated as a
Solid Waste Manaqement Unit (SWMU) subject to the RCRA/CERCLA process.

The BRP6G is located to the south and is immediately adjacent to the construction laydown
area. In addition, the BRP6G is located approximately 300 feet southeast of the Ford
Buildinq Seepaqe Basin and is also located southeast and downqradient of the Ford Buildinq Waste
Site. The Federal Facility Aqreement (FFA) field start for the RFI/RI for the Ford Seepaqe
Basin is scheduled for 10/20/97. A time-critical removal action for Cesium-137 beqan on
12/18/96 for the Ford Buildinq Waste Site.

Compliance History

At SRS, waste materials requlated under the Resource Conservation & Recovery Act (RCRA) are

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managed in accordance with the requirements of RCRA. Certain SRS activities have required
treatment, storage, disposal or post-closure permits under RCRA. Non-regulated units, called
solid waste management units (SWMU), include any activity where hazardous constituents may
remain uncontrolled and may potentially release to the environment. Investigation and potential
corrective action for these SWMU(s) are mandated under RCRA 3004(u). On September 5, 1995,
SRS received a hazardous waste permit from the South Carolina Department of Health and
Environmental Control (SCDHEC) which includes corrective action requirements. Specifically,
part V of the permit mandates that SRS establish and implement a RCRA Facility Investigation
(RFI) Program to fulfill the requirements specified in Section 3004(u) of RCRA.

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

The remedial investigation for the Central Shops Burning/Rubble Pit (631-6G) (BRP6G)was
completed in 1995. The results of the investigation indicate that there is no impact (or
potential impact) to human health or the environment from the BRJP6G. Therefore, no action is
warranted. No other alternatives were considered.

According to EPA guidance, if there is no current or potential threat to human health and the
environment and no action is warranted, the CERCLA 121 requirements, are not triggered. This
means that these is no need to evaluate other alternatives or the no action alternative against
the nine criteria specified under CERCLA.

The remedy selected satisfies both the CERCLA and RCRA 3004(u) requirements. The SCDHEC
has modified the SRS RCRA permit to incorporate the selected remedy.

III. HIGHLIGHTS OF COMMUNITY PARTICIPATION

Both RCRA and CERCLA require that the public be given an opportunity to review and comment on
the draft permit modification and proposed remedial alternative. Public participation
requirements are listed in South Carolina Hazardous Waste Management Regulation
(SCHWMR) R.61-79.124 and Sections 113 and 117 of CERCLA. These requirements include
establishment of an Administrative Record File that documents the investigation and selection of
the remedial alternatives for addressing the BRP6G soils and groundwater. The Administrative
Record File must established at or near the facility at issue. The SRS Public Involvement Plan
(DOE, 1994) is designed to facilitate public involvement in the decision-making process for
permitting, closure, and the selection of remedial alternatives. The SRS Public Involvement Plan
addresses the requirements of RCRA, CERCLA, and the National Environmental Policy Act. SCHWMR
R.61-79.124 and Section 117(a) of CERCLA, as amended, required the advertisement of the draft
permit modification and notice of any proposed remedial action and provided the public an
opportunity to participate in the selection of the remedial action. The Statement of
Basis/Proposed Plan for the Central Shops Burning/Rubble Pit 631-6G) (WSRC, 1996b), which is
part of the Administrative Record File, highlights key aspects of the investigation and
identifies the preferred action for addressing the BRP6G.

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

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

       Thomas Cooper Library
       Government Documents Department
       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 University
       Tompkins Road
       Savannah,  Georgia 31404
       (912)  356-2183

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

The 45-day public comment period began on December 10, 1996 and ended on January 23.
1997.  A Responsiveness Summary was prepared to address comments received during the public
comment period.  The Responsiveness Summary is provided in Appendix A of this Record of
Decision.  The public comment period for the RCRA Permit Modification began on January 27, 1997
and ended on March 12, 1997.

IV.    SCOPE AND ROLE OF OPERABLE UNIT WITHIN THE SITE STRATEGY

The overall strategy for addressing the BRP6G was to:  (1) characterize the waste unit
delineating the nature and extent of contamination and identifying the media of concern  (perform
the RFI/RI);  (2)  perform a baseline risk assessment to evaluate media of concern, constituents
of concern (COCs), exposure pathways, and characterize potential risks; and (3)  evaluate and
perform a final action to remediate, as needed, the identified media of concern.

The BRP6G is a source control and groundwater operable unit which is included in the Pen Branch
watershed.  Drainage from the Pen Branch water shed area which includes the BRP6G eventually
flows to Pen Branch.  The Pen Branch watershed area which includes the BRP6G is approximately
15 square miles  (9,600 acres).  The BRP6G covers 0.75 acres or 0.008 percent of the water shed.

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No remedial action, which is the preferred remedy, is a final action.

V. SUMMARY OF OIERABIiE UNIT CHARACTERISTICS

Media Assessment

The Data Summary Report (WSRC, 1995) and RFI/RI/BRA (WSRC, 1996a) contain detailed analytical
data for all of the environmental media samples taken in the characterization of BRP6G. These
documents are available in the Administrative Record File.

The soils were sampled in two investigations. In the first investigation (March - April 1994),
ten soil borings were made. A minimum of four samples were collected from each borehole.
Samples included surface soil samples, subsurface soil samples, and deep soil samples down to
the water table. The second investigation (November 2 - December 30, 1994) included 12 soil
borings, the collection of six surface samples, collection of five surface water/sediment
samples, and the installation of three temporary groundwater monitoring wells.

The 17 onsite borings were labeled CS6G 1-9, 11-17, and 22. The five background borings were
labeled CS6G 10, 18, 19, 20, and 21 (See Figure 4).

Samples from three permanent groundwater monitoring wells were also in this study. The wells
used were designated as follows: CBR1 (upgradient); CBR2, 3, 4, and 6
(sidegradient/downgradient); and CBR5 (downgradient) (see Figure 3). The results of the
investigation are discussed in the following sections.

Soils

A total of 74 soil samples were collected and analyzed. Low levels of metal, semi-volatile,
volatile, pesticide, polychlorinated biphenyl (PCB), dioxin/furan, and radionuclide indicators
were detected in the soil samples from soil borings in this unit. The constituents were
detected in greatest concentrations in samples located at the bottom of the pit in the soils, as
expected based on the conceptual model.

The following three sections provide a summary of the nature and extent of constituents
exceeding background and focuses on those constituents that exceed risk assessment and
leachability screening criteria.

Surface Soil (0-2 feet) Summary

Constituents that were detected above the two times average background concentration include
21 metals, 16 semi-volatiles, 13 volatiles, 4 pesticides, PCB-1254, octachlorodibenzo-p-dioxin
(OCDD), and radionuclide indicators (three locations). The locations where the exceedances
of background occurred are fairly evenly distributed between borings located inside and outside
of the pit. Of all of the constituents found above background, seven were designated as
contaminants of potential concern (COPCs) in the baseline risk assessment, which are presented
in Table 1. With the exception of OCDD, which was found only in the eastern third of the unit,
the other constituents were randomly distributed across the unit. PCB-1254 was detected only
once in soil boring location CS6G-12. Octachlorodibenzo-p-dioxin was detected at three
locations outside of the pit and one inside the pit.

Risks (hat were determined for surface soils constituents of potential concern can be found in

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Section VI.

Shallow Subsurface Soil (0-5 feet) Summary

Constituents that were above the two times average background concentration are essentially
the same as in the surface soils, which is consistent with the conceptual site model given
that this zone is predominantly fill material. Eight of the constituents found above two times
the average background concentration were designated as COPCs, which is presented in Table
2. Beryllium, the additional COPC not included in the 0-2 foot interval, is also randomly
distributed across the unit.

These COPCs were evaluated for their potential contribution to risk in Section IV. The 0-5 foot
soil interval is evaluated for a possible future excavation scenario which could bring these
constituents to the surface where they could come into contact with humans or the environment

Leachability From Soils

One of the concerns regarding the site specific contaminants (SSCs) that have been identified in
the vadose zone is whether the potential exists for these contaminants to migrate to the water
table in a sufficient guantity over time such that future groundwater concentrations could
create a risk (i.e. exceed MCLs or other risk based criteria). The SSCs are contaminants found
in the vadose zone from 0 feet to the water table. Contaminants were identified as SSCs based
upon their freguency of detection above two times the average background and their health risks
and/or mobility. The SSCs include seven inorganic constituents, nine semi-volatiles, six
volatiles, two pesticides and OCDD. The average soil concentration of the SSCs were compared to
generic EPA soil screening levels (SSLs). Those failing generic SSLs were further compared to
site specific soil screening levels. Only barium, chromium, benzo(a)pyrene,
benzo(b)-fluoranthene, and dieldrin possessed an average concentration which was above the site
specific SSL value. This screening process is demonstrated in Table 3.

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                                                Table 1  Analytes and COPCs in Surface Soil (0-2  ft)  Used in Calculations of Risk & Hazard

Unit

ing/ kg
ing/ kg
ing/ kg
ing/ kg
ing/ kg
ing/ kg
ing/ kg
Number
of
Detects
1
1
4
1
25
8
2
Total
Number
for Samples
7
25
25
25
25
25
25
Detection
Limit Range
for Undetects
0.1-0.12
0.2-0.25
0.74-0.9
0.21-0.25
No undetects
0.05
10.6-12
Maimmum
Detected
Concentration
0.00038
0.0146
7.92
0.0219
31400
0.00759
0.115


UL 95
0.000228
0.000554
1.97
0.000643
14302.98
0.001358
0.02302
Exposure
Concentration
(a)
0.000228
0.000554
1.97
0.000643
14302.98
0.001358
0.023023
        Analyte
2-Hexanone
Anthracene
Arsenic
Benzo  (g,h,i)perylene
Iron
OCDD
PCB-1254
 (a)  Exposure concentration is the lesser of the maximum detected and the UL 95.
                                                                     Average
                                                              Concentration
                                                                   (Background)
                                                                                                                                              Not Detected
                                                              Not Detected
                                                                 Not Detected
                                                                   Not Detected
                                                                   13487.78
                                                              0.00033
                                                                 Not Detected
                                          Table 2  Analytes and COPCs in Shallow Subsurface Soil  (0-5 ft) Used in Calculations of Risk & Hazard
        Analyte
2-Hexanone
Anthracene
Arsenic
Benzo  (g,h,i)perylene
Beryllium
Iron
OCDD
PCB-1254

Unit

mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
Number
of
Detects
1
1
7
1
37
37
14
2
Total
Number
of Samples
9
37
37
37
37 No
37
37
37
Detection
Limit Range
for Undetects
0.1-0.12
0.21-0.33
0.74-1.24
0.21-0.33
detects
No detects
0.05-0.07
10.6-16.6
        Maximum
        Detected
  Concentration

      0.00038
0.37
                                                                                                            UL 95
                                                                                                            0.000194
      Exposure
   Concentration
          (a)

0.000194
       Average
Concentration
      (Background)
                                                                                                                                              Not Detected
0.






,0146
9.22
0.0219
0.161
49300
0.0194
0.115
0.000405
2.379
0.000445
0.161
20218.560
0.004
0.01925
      0.000405
         2.379
         0.000445
              0.15
         20218.56
   0.004064
         0.019254
 Not Detected
       1.15
     Not Detected

      17127.86
 0.00096
    Not Detected
 (a)  Exposure concentration is the lesser of the maximum detected and the UL 95.

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The two contaminants, benzo(a)pyrene and benzo(b)fluoranthene, had exceedingly high average
concentrations due mainly to the two samples from borings in the pit. These samples CS6G 1404
(4-6 ft.) and CS6G 0902 (3.56-5.6 ft.) had inordinately high concentrations of all of the
polycyclic aromatic hydrocarbons because of their position in the pit, that is, the samples were
taken directly at the position of the burned material at the base of the pit. The samples taken
two feet below these samples exhibited concentrations in the range of ten to one hundred times
lower than the previous samples, and were considerably lowerthan the EPA SSL values. The
inherent insolubility of polycyclic aromatic hydrocarbons and the soil cover of this
burning/rubble pit has apparently served to inhibit the movement of these substances toward the
groundwater, as the highest concentrations are located where they were forty years ago when the
pit was covered.

Dieldrin was also noted as having an average concentration above the site specific SSL. This
contaminant was only detected in five out of seventy-four samples. Three of the samples are
above the SSL, with an average of 0.0022 mg/kg. The average concentration of dieldrin was based
on only five detections out of seventy-four samples analyzed which is very conservative. If all
the samples were taken into consideration for determining the average, the average would be
considerably less. Thus based on the conservative assumptions used in the model and the
empirical data, dieldrin is not expected to impact groundwater in the future. Dieldrin was only
detected in the top four feet of the samples analyzed.

The RCRA Facility Investigation/Remedial Investigation/Baseline Risk Assessment performed an
analysis that indicates that dieldrin could migrate to the groundwater and would reach the
groundwater in 28.1 years with a concentration of 0.00219 mg/L. The risk at this concentration
is calculated to be 7.89 x 10 -6, which is above the 10 -6 threshold. The length of time that
the site has been undisturbed is in excess of the 28.1 years, and dieldrin has not migrated to
detectable guantities below the four foot level in soils and has not been detected in
groundwater. Further, the limited soil data that is available delineates a clayey soil which
would also inhibit migration.

Barium was detected in the soil with an average concentration of 23.56 mg/kg. Modeling
predicted that measurable levels of barium would reach the groundwater, however, the hazard
index calculation showed that barium poses no undue risk to future residents or future
industrial workers.

Groundwater modeling also predicted that chromium would migrate to the groundwater in measurable
levels. Chromium +3, the dominant oxidation state for this environment, poses a minimal risk
with a hazard index of 0.004 for the future resident from ingestion of groundwater peaking at a
time in excess of 570 years in the future. Although not considered to be present, chromium in
the +6 state would pose a risk with a hazard index of 2 for the future resident from ingestion
of groundwater. The time to peak groundwater concentration is in excess of 570 years in the
future. For these reasons, chromium will not have an unacceptable impact on future groundwater
guality.

Barium, chromium, benzo(a)pyrene, benzo(b) fluoranthene, and dieldrin exhibit average soil
detection concentrations which exceed site specific SSLs. Based on the previous discussions
regarding the behavior of the specific BRP6G SSCs in the environment, groundwater modeling
results, and the results of the comparison to site specific SSLs, the contaminants present in
the soils at the BRP6G have little likelihood of impacting future groundwater guality. This is
due mainly to the nature of the locations of the highest contaminants concentrations being in
the charred material in the case of the polycyclic aromatic hydrocarbons (PAHs), minimal
increases in the hazard indices for future residents from ingestion of groundwater predicted

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from groundwater modeling for barium and chromium which peak at over 570 years from the present,
and detections only in the upper four feet of soil in the case of the dieldrin.

Sediment/Surface Water

There are no surface water impoundments in the vicinity of BRP6G. Drainage water samples were
collected in the downgradient ditch at five locations. The source of the drainage water is not
entirely from BRP6G. Upgradient surface water runoff originates from a large construction
materials lay-down yard and the Ford Building area. Both upgradient and downgradient surface
water samples indicated the presence of metals, semi-volatile organics, volatile organics, and
radionuclides.

Both upgradient and downgradient sediment samples indicated the presence of various metals,
small amounts of volatiles organics, semi-volatile organics, gross alpha radionuclides, and
OCDD.

Because of the uncertainty of the origin of the analytes detected in the surface water and
sediment, the data collected cannot be utilized to effectively characterize the BRP6G site.
Regardless of their origin, the levels of contaminants detected would pose insignificant human
health risk based on typical exposure assumptions. The potential environmental impact of these
contaminants will be addressed on a larger scale in the Pen Branch watershed assessment.

Groundwater

A total of 27 groundwater samples were collected. Compounds that were intermittently detected
more than once in wells downgradient from the pits include: aluminum,
bis(2-ethylhexyl)phthalate (B2EHP), bromo-dichloromethane, chloroform, and
dibromo-chloromethane.

The following is a list of groundwater contaminants of potential concern (COPCs) with their
maximum detected levels for all constituents and the criteria that they exceed, and the Standard
Value.

COPC Maximum Criteria Standard
Value (pg/L) Exceeded (Ig/L)
Aluminum
Arsenic
Beryllium
Iron
Lead
Manganese
41,400
5.1
0.409
98,900
89.1
297
4
1,2
1
2,4
3,5
4
50
50
4
300
15,50
50
B2EHP 6.11 1,2,3 6

1) caused risk in excess of 1 x 10 -6
2) caused Hazard Index (HI) values to exceed 1
3) exceeded MCLs (federal or State)
4) exceeded the Secondary Drinking Water Standards
5) exceeded EPA at-the-tap action level.

Lead was detected at a concentration above the EPA at-the-tap action level (15 Ig/L) and the
South Carolina groundwater protection standard (50 Ig/L) in well CBR4 with a detection of 89.1
Ig/L. This sample was collected with a bailer and was very turbid. Turbid samples tend to have
much higher levels of metals present than clear samples. For this reason, this level of lead is

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suspect and may not represent the actual conditions in the groundwater. A subsequent sample
taken from the same well 25 days later showed a level of only 11.8 pg/L which is below both the
EPA and the South Carolina standards.

Bis(2-ethylhexyl)phthalate, a semi-volatile, exceeded the Primary Drinking Water Standard
concentration of 6.0 Ig/L in the same sample with a value of 6.11 Ig/L. Subsequent sampling in
the same well 25 days later showed bis(2-ethylhexyl)phthalate at 0.254 Ig/L.

All of the constituents (arsenic, beryllium, lead, and bis(2-ethylhexyl)phthalate) providing
risk or detections above MCLs were obtained from monitoring well CBR4. None of these
constituents was consistently detected above their associated MCLS. Well CBR4 is located west
of the unit in a hydrologically side to up gradient position. It would be unlikely that any
constituents detected in this well could be from this unit. The most likely source, if
constituents were consistently detected in this well, would be upgradient of this unit. It
should be noted that these constituents were not detected above MCLs in the downgradient well
(CBR5). This data, in conjunction with the frequency and occurrence of detections, suggest
that there is little or no impact from the unit to the groundwater.

The Secondary Drinking Water Standards are primarily for esthetic purposes and are not
enforceable standards for groundwater.

The uncertainty associated with the groundwater results is discussed further in the Uncertainty
section.

VI. SUMMARY OF OIERABIiE UNIT RISKS

As a component of the remedial investigation process, a baseline risk assessment was prepared
for the BRP6G. The baseline risk assessment consists of human health and ecological risk
assessments. Summary information for the human health and ecological risk assessments follows.

Human Health Risk Assessment

As part of the investigation/assessment process for BRP6G, a BRA was performed using data
generated during the assessment phase. The BRA is described in the RFI/RI/BRA report (WSRC,
1996a).

The BRA designates the COPCs based on a conservative screen against background concentrations,
and the relative potential of the chemicals to cause toxic or carcinogenic effects.

An exposure assessment was performed to provide an indication of the potential exposures which
could occur based on the chemical concentrations detected during sampling activities. The only
current exposure scenario identified for BRP6G was for on-site visitors. Conservative future
exposure scenarios identified for BRP6G included future industrial workers and future resident
adults and children. The reasonable maximum exposure (RME) concentration value was used as the
exposure point concentration.

Carcinogenic risks are estimated as the incremental probability of an individual
developing cancer over a lifetime as a result of pathway-specific exposure to cancer-causing
contaminants. The risk to an individual resulting from exposure to non-radioactive chemical
carcinogens is expressed as the increased probability of cancer occurring over the course of a
70 year lifetime. Cancer risks are related to the EPA target risk range of one in ten thousand
(1 x 10 -4) to one in one million (1 x 10 -6) for incremental cancer risk at NPL sites. Risk
levels in the 1 x 10 -4 to 1 x 10 -6 range require a risk management decision where specific
actions to reduce risk may be considered while cancer risk levels below 1 x 10 -6 are considered

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to be insignificant.

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

Current Land Use - Noncarcinogenic Hazards

The BRA shows that potential adverse noncarcinogenic health effects are not likely to occur,
because none of the His exceeded a value of one.

Current Land Use - Carcinogenic Risks

Under the current land use scenario, human health risks were calculated for both the current
material yard worker and the current groundwater sampler. The only pathway that exceeded 1 x 10
-6 was inhalation of groundwater which was 2 x 10 -6 from chloroform. The risk for inhalation
from groundwater was calculated using very conservative methods which assumed that all of
the chloroform in the water vaporized and was inhaled during the groundwater sampling. Thus
the total risks to current workers are considered to be insignificant. Figure 5 summarizes
these calculations.

Future Industrial Land Use - Noncarcinogenic Hazards

The only HI value for the hypothetical future industrial worker that exceeds 1.0 is for
ingestion of groundwater (see Figure 6). The 2.5 value for ingestion of water is driven by
Future Industrial Land Use - Carcinogenic Risks

For the hypothetical future worker, only the total carcinogenic risk, by pathway, from ingestion
of groundwater (1 x 10 -5) exceeds 1 x 10 -6 (see Figure 6). This risk is driven by arsenic and
beryllium.

Future Residential Land Use - Noncarcinogenic Hazards

Two His for hypothetical future resident adults exceeded a value of 1.0 (see Figure 7). These
were: 1.1 for ingestion of soil, driven by iron and arsenic; and 23 for ingestion of
groundwater, driven by iron. One HI exceeded 1.0 for a hypothetical future resident child.
This was 16 for ingestion of groundwater, driven by iron (from the bailed sample).

Future Residential Land Use - Carcinogenic Risks

The total carcinogenic risk for the hypothetical future resident adult is 8 x 10 -5 (see Figure
7). The following carcinogenic risks egualed or exceeded 1 x 10 -6: 2 x 10 -6 for inhalation
of soil from arsenic, 8 x 10 -6 from ingestion of soil from arsenic, 1 x 10 -6 for inhalation of
groundwater driven by bis(2-ethylhexyl)phthalate and bromodichloro-methane, 6 x 10 -5 for
ingestion of groundwater due to arsenic and beryllium, 4 x 10 -6 for ingestion of homegrown

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tuberous produce due to OCDD and PCB-1254, and 7 x 10 -6 for ingestion of homegrown fruit due to
OCDD and PCB-1254.

The total carcinogenic risk for the hypothetical future child resident is 3 x 10 -5. Several
carcinogenic risks equaled or exceed 1 x 10 -6: 1 x 10 -6 for inhalation of soil driven by
arsenic; 6 x 10 -6 for ingestion of soil driven by arsenic and beryllium; 2 x 10 -5 for
ingestion of groundwater driven by arsenic and beryllium 1 x 10 -6 from ingestion of homegrown
tuberous produce due to OCDD and PCB-1254, and 2 x 10 -6 from ingestion of homegrown fruit due
to OCDD and PCB-1254.

Uncertainty

Risks from arsenic, beryllium, and iron in the pit soil were calculated since a conservative
screening method (comparison of site maximum to two times the background mean) indicated that
they were elevated above background levels. Background levels of organic compounds (e.g., OCDD)
are not considered in the risk assessment, however, the observed concentration ranges for both
on-site and background samples are very similar. OCDD was detected in both surface and shallow
subsurface background samples. OCDD has been found randomly distributed in SRS background
samples. A statistical comparison between site samples and background samples for arsenic,
beryllium, and OCDD indicated with 90 percent confidence that the site and background samples
are part of the same distribution with the exception of arsenic in the 0-5 foot interval.

The contribution of risk (from background concentrations of arsenic and iron are significant
when compared to the onsite values. For the 0-5 ft exposure unit, the background RME for
arsenic is 2.30 mg/kg, as compared to 2.38 mg/kg on unit. The background RME for iron is
22,710, as compared to the on unit value of 20,218 mg/kg.

The main contributors to groundwater risk are arsenic and beryllium. Lead exceeded the EPA at
the-tap guidance while bis(2-ethylhexyl)phthalate exceeded the groundwater MCL. The analytical
values used for all four of these constituents came from the December 3, 1994 sampler from well
CBR4. This sample was highly turbid. A subsequent sample taken from the same well 25 days
later showed reduced values for all of these constituents. If this sample was not included in
the risk analysis, arsenic and beryllium would contribute considerably lower risks. Removal of
this sample from consideration would also eliminate the only MCL exceedeaces (lead and
bis(2-ethylhexyl)phthalate) found at BRP6G. The values from these sampling events are shown
below:
(Ig/L) (Ig/L)
Constituent 12/3/94 12/28/94

Arsenic 5.1 ND
Beryllium 0.739 0.409
Lead 89.1 11.8
B2EHP 6.11 0.254

The risk for groundwater ingestion from arsenic is based on one detection in a bailed sample.
This risk is highly suspect since only one of 27 groundwater samples detected arsenic and this
was from a bailed sample. Bailed samples often remove water which contains suspended solids and
concentrated levels of contaminants which may not be, representative of the actual groundwater.
To verify this anomaly, an additional sample was taken from this same well 25 days later.
Arsenic was not detected in this sample.

The only detection of beryllium in groundwater in excess of two times background was from the
same 12/3/94 turbid sample taken from well CBR4.

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The only groundwater detection of lead and bis(2 ethylhexyl)phthalate in excess of their
respective maximum contaminant levels (MCL) was from the same 12/3/94 turbid, bailed sample from
CBR4.

All of the detections for aluminum, manganese, and iron which exceeded the Secondary Drinking
Water Standards were also from the turbid samples taken from well CBR4. The levels of iron used
to calculate His of 23 for future residents and 16 for a future child for ingestion of
groundwater attributed were also obtained from the same samples. Elimination of the data from
these turbid samples would remove all detections over the Secondary Drinking Water Standards and
the His for ingestion of groundwater in excess of 1.

All of the constituents (arsenic, beryllium, lead, and bis(2-ethylhexyl)phthalate) providing
risk or detections above MCLs were obtained from monitoring well CBR4. None of these
constituents was consistently detected above their associated MCLS. Well CBR4 is located west
of the unit in a hydrologically side to up gradient position. It would be unlikely that any
constituents detected in this well could be from this unit. The most likely source, if
constituents were consistently detected in this well, would be upgradient of this unit. It
should be noted that these constituents were not detected above MCLs in the downgradient well
(CBR5). This data, in conjunction with the freguency and occurrence of detections, suggest
that there is little or no impact from the unit to the groundwater.

Discounting the analysis of This sample would eliminate any MCL exceedences for groundwater
associated with BRP6G.

Ecological Risk Assessment

Based on characterization of the environmental setting at BRP6G and identification of potential
receptor organisms (plants and animals), a conceptual site model was developed to determine how
plants and animals could be exposed to COPCS.

Evaluation of the concentrations of lead, copper, PCB, and cadmium along with their toxicity,
and the limited habitat provided by BRP6G result in a determination that ecological risk is
insignificant.

Site-Specific Considerations

Site-specific considerations, based on the conclusions of the BRA and RFI/RI, which suggest
limited or no potential for significant risk include:

1) BRP6G contains a large volume of buried nonhazardous waste material and cover soil.

2) The levels of surface soil contamination recognized during characterization are generally
very low. The contaminants in the trench bottom soils are very stable chemically and
exhibit limited mobility in the soil as indicated by the deep soil sampling results.
3) The groundwater monitoring program indicates that there has not been significant impact
from the waste materials in the pits.

Remedial Action Objectives

Remedial action objectives specify unit-specific contaminants, media of concern, potential
exposure pathways, and remediation goals. Remediation goals are developed based upon
ARARs or can be risk-based.

ARARs are those cleanup standards, standards of control, and other substantive reguirements,

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criteria, or limitations promulgated under federal, state, or local environmental law that
specifically address a hazardous substance, pollutant, contaminant, remedial action, location,
or other circumstance at a CERCLA site. Other available information that is not an ARAR (e.g.,
advisories, criteria, guidance) may be considered in the analysis if it helps to ensure
protectiveness or is otherwise appropriate for use in a specific alternative. These guidances
are referred to as to-be-considered (TBC) guidances. Three types of ARARs; action-, chemical-,
and location-specific; have been developed to simplify identification and compliance with
environmental reguirements. Action-specific reguirements set controls on the design,
performance and other aspects of implementation of specific remedial activities.
Chemical-spicific reguirements are media specific, health-based concentration limits developed
for site-specific levels of contaminants in specific media. Location-specific ARARs must
consider federal, state, and local reguirements that reflect the physiographical and
environmental characteristics of the unit or the immediate area.

In the future industrial land use scenario which is probable based on current land-use
designation for this area all of the soil related risks are below 1 x 10 -6.

In the future residential land use scenario, the contaminants that contributed to the risk
exceeding 1 x 10 -6 from soil exposure were arsenic, beryllium, iron, OCDD, and PCB-1254.
Of these, the concentrations of arsenic, beryllium, iron, and OCDD were statistically either
shown to be eguivalent to background levels or insignificantly elevated above background. The
only remaining risk attributed to the pit soil is 2 x 10 -6 due to PCB-1254 via ingestion of
produce grown on-site. The maximum concentration of PCB-1254 detected in the pit was 0.115
mg/kg and PCBs were detected in only two of 37 samples. For these reasons, soil remediation is
not needed at BRP6G to be protective of human health and the environment. Potential future
risks associated with the residual contamination at the unit, are acceptable.

There were no remedial action-specific or location-specific ARARs relevant to establishing
remedial action objectives for the BRP6G source unit. There also were no chermcal-specific
ARARs identified, however there is TBC guidance. TBC guidance for PCB contamination in soils is
found in the Toxic Substances Control Act and EPA guidance (EPA, 1990). These TBC guidances
list soil action levels of 1 ppm PCB in soils for residential use and 10-25 ppm in soils for
industrial use. BRP6G is well below the residential soil action level.

One potential remedial action objective for groundwater is to ensure that all groundwater is
below MCLs. The only MCL that was exceeded was for bis(2-ethylhexyl)phthalate. The maximum
value detected was 6.11 Ig/L which slightly exceed the MCL of 6 Ig/L. This value is likely
not representative of the concentration of bis(2ethylhexyl)phthalate in the groundwater because
a subseguent sample taken from the same well 25 days later showed a value of only 0.254 pg/L.

An additional potential remedial action objective is for the groundwater to meet the EPA's
at-the-tap guidance. Lead is the only constituent to exceed this guidance. The 12/3/94 turbid
sample from CBR4 had a value of 89.1 Ig/L which exceeds the guidance value of 15. A subseguent
sample taken from the same well 25 days later measured 11.8 Ig/L.

Arsenic and beryllium both are risk-based containinants of concern for groundwater at the BRP6G.
Arsenic was found in only one of 27 groundwater samples and was not included in risk
calculations based on the low freguency of detection. In addition, when the well was resampled
25 days later, arsenic was not detected. This indicates that this was an atypical value and
is not representative of the actual groundwater conditions.

Beryllium was found in only one groundwater sample at levels that exceeded two times the
background level for groundwater. This was from a turbid sample and likely contains higher
levels of metals than a truly representative sample would contain. Beryllium is not associated

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with known activities in the BRP6G, but is prevalent in the clayey soils in the area.  For these
reasons, it is unlikely that the groundwater is being contaminated with berylhum from BRP6G.

For the reasons stated above, there are no remedial actions reguired for soil or groundwater to
protect human health and the environment.  The remedial action objective for BRP6G is,
therefore, no remedial action.

VII.   THE SEIiECTED REMEDY

The selected remedy for BRP6G is No Action.

If the property is ever transferred to non-federal ownership, the U. S. Government will create a
deed for the new property owner which will contain information in compliance with CERCLA 120
(h).  The deed shall include notification disclosing former waste management and disposal
activities as well as remedial actions taken at the site.  The deed notification shall, in
perpetuity, notify any potential purchaser that the property has been used for the management
and disposal of construction debris and other materials, including hazardous substances.  In
addition, if the site is ever transferred to non-federal ownership, a survey plat of the area
will be prepared, certified by a professional land surveyor, and recorded with the appropriate
county agency.

This proposal is consistent with EPA guidance and is an effective use of risk management
principles.  The Statement of Basis/Proposed Plan provided for involvement with the community
through a document review process and a public comment period.  Public input is documented in
the responsiveness summary in Appendix A.

VIII. STATUTORY DETERMINATIONS

Based on the BRP6G RCRA Facility Investigation/Remedial Investigation  (RFI/RI)  Report, the
Baseline Risk Assessment (BRA) ,  and the uncertainty analysis, the BRP6G poses no
significant risk to human health and the environment.  While unit-related risk levels exceed
1 x 10 -6, a risk management decision was made to implement the No action alternative.

The selected remedy is protective of human health and the environment and complies with federal
and state reguirements that are legally applicable or relevant and appropriate to the remedial
action.  No Action will result in hazardous substances, pollutants, or contaminants remaining in
the source Unit.

IX.    EXPLANATION OF SIGNIFICANT CHANGES

There were no significant changes made to the Record of Decision based on comments received
during the public comment period for the Statement of Basis/Proposed Film Comments that
were received during the public comment period are addressed in Appendix A.

X.     RESPONSIVENESS SUMMARY

A Responsiveness Summary of the comments received during the public comment period is included
in Appendix A.

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

DOE, 1996. Savannah River Site Future Use Project Report. U. S. Department of Energy
Savannah River Operations Office, Aiken, South Carolina, January, 1996.

EPA (U. S. Environmental Protection Agency), 1990. A Guide on Remedial Actions at
Superfund Sites with PCB Contamination. Office of Emergency and Remedial Response.
Directive 9355.4-01 FS, (August 1990).

EPA, 1991. OSWER Directive 9355.0-30, Role of the Baseline Risk Assessment in Superfund
Remedy Selection Decisions. Office of Solid Waste and Emergency Response, (April 22,
1991).

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

WSRC (Westinghouse Savannah River Company), 1995. Data Summary Report for the RFI/RI
Assessment Sampling at Central Shops Burning/Rubble Pit Waste Unit. WSRC-RP- 95-1546,
Revision 1, Westinghouse Savannah River Company, Aiken, South Carolina (March 1996).

WSRC, 1996a. RCRA Facility Investigation/ Remedial Investigation Report With Baseline
Risk Assessment for the Central Shops Burning/Rubble Pit (631-6G) (U), WSRC-RP- 95-1539,
Revision 1.1, Westinghouse Savannah River Company, Aiken, South Carolina (April, 1996).

WSRC, 1996b. Statement of Basis/Proposed Plan for the Central Shops Burning/Rubble Pit
(631-6G) (U), WSRC-RP-96-142, Revision 1, Westinghouse Savannah River Company, Aiken,
South Carolina (October 1996).

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                                                  APPENDIX A

                                            RESPONSIVENESS SUMMARY

The public comment period for the Statement of Basis/Proposed Plan for the Central Shops
Burning/Rubble Pit (631-6G) began on December 10, 1996 and ended on January 23, 1997.  The
public comment period for the RCRA Permit Modification began on January 27, 1997 and ended on
March 12, 1997.

Public Comments

No oral, written, phoned, or e-mailed comments were received from the public.

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