United States Office of
Environmental Protection Emergency and
Agency Remedial Response
EP/VROD/R04-93/166
September 1993
EPA Superfund
Record of Decision:
USDOE Oak Ridge Reservation
(Operable Unit 16), TN
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50272-101
REPORT DOCUMENTATION
PAGE
1. REPORT NO.
EPA/ROD/R04-93/166
3. Recipient's Accession No.
4. TrUeandSubtitte
SUPERFUND RECORD OF DECISION
USDOE Oak Ridge Reservation (Operable Unit 16), TN
Eighth Remedial Action
& Report Data
09/30/93
7. Authors)
a Performing Organization Rapt. No.
9. Parforming Organization Nanw and Address
10 Project Task/Work UnM No.
11. Contract(C) or Grant(G) No.
(G)
12. Sponsoring Organization Nanw and Address
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
13. Typs of Report & Period Covered
800/800
14.
1& Supplementary Notes
PB94-964021
16. Abstract (Limit: 200 words)
The USDOE Oak Ridge Reservation (Operable Unit 16) site is part of the former uranium
enrichment K-25 facility located in Oak Ridge, Roane County, Tennessee. Land use in
the area is mixed agricultural, recreational, residential, and industrial. Site
features include Poplar Creek, Clinch River, Mitchell Branch, and two former waste
disposal ponds. From 1945 to 1985, the K-25 facility operated as part of the Manhattan
Project and was the world's first large-scale uranium enrichment facility. In 1943,
the K-1407-B Pond was constructed as a settling and holding pond to receive metal
hydroxide precipitates generated during neutralization and precipitation of metal-laden
solutions treated in the K-1407-A Neutralization Unit. The pond also received
discharges from the K-1420 Metals Decontamination Building and waste from the K-1501
Steam Plant. In 1973, the K-1407-C Pond was constructed to store the potassium
hydroxide scrubber sludge generated at K-25 and to receive sludge discharges from the
K-1407-B Pond. Once the K-1407-B Pond reached maximum sludge capacity, it was dredged,
and the sludge was transferred to the K-1407-C Pond. In 1985, sampling was conducted
to characterize the waste in the pond sludge and subsurface soil. In 1987 and 1988,
DOE removed sludge from the K-1407-C and K-1407-B Ponds to comply with RCRA clean
closure requirements. Subsequent sampling confirmed the presence of residual
(See Attached Page)
17. Document Analysis a. Descriptors
Record of Decision - USDOE Oak Ridge Reservation (Operable Unit 16), TN
Eighth Remedial Action
Contaminated Medium: soil
Key Contaminants: VOCs (PCE, TCE), metals (arsenic, chromium), radioactive materials
b. Identifiers/Open-ended Terms
COSATI Field/Group
ia Availability Statement
19. Security Class (This Report)
None
20. Security Class (This Page)
None
21. No. of Pages
122
22. Price
(SeeANSi-Z39.18)
SM Instruction* on Reverse
OPTIONAL FORM 272 (4-77)
(Formerly MT1S-35)
Department of Commerce
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EPA/ROD/RO4-93/166
USDOE Oak Ridge Reservation (Operable Unit 16), TN
Eighth Remedial Action
Abstract (Continued)
radionuclide contamination in the pond soil. As a result, RCRA closure activities were
halted until a new strategy could be developed to integrate RCRA/CERCLA requirements.
Previous 1991 and 1992 RODs addressed contaminated soil, sludge, and debris at the United
Nuclear Corporation disposal site; contaminated sediment at the Y-12 Plant; contaminated
sludge at the K-25 facility; contaminated surface water at the K-25 facility; and
contaminated soil at the Y-12 Plant, as OUs 2, 3, 4, 6, and 18, respectively. Other 1993
RODs address contaminated surface debris and soil at the Oak Ridge National Laboratory, as
OUs 8 and 17, respectively. This ROD addresses the contaminated K-1407-B and K-1407-C
Ponds at the K-25 facility, as OU16. A future ROD will address onsite contaminated ground
water. The primary contaminants of concern affecting the soil are VOCs, including PCE and
TCE; metals, including arsenic and chromium; and radioactive materials.
The selected remedial action for this site includes implementing stormwater runoff
controls and fugitive dust controls; filling K-1407-B Pond, which contains 21,000 yd3 of
soil with residual contamination with approximately 14,000 yd3 of crushed rock and
K-1407-C Pond with approximately 63,000 yd3 of engineered compacted soil; placing a soil
cover over the filled ponds; regrading and revegetating the pond areas to control erosion
and stabilize the soil covers; monitoring ground water; and maintaining existing
institutional controls and site access restrictions. The estimated present worth cost for
this remedial action is $5,000,000, which includes an estimated annual OSM cost of
$33,000.
PERFORMANCE STANDARDS OR GOALS:
Chemical-specific soil cleanup goals are based on a health-risk level of 10" ,
EPA-recommended equations for calculating preliminary remediation goals for radionuclides
in soil, and RCRA clean closure requirements, and include americiuirT^l Q.002 pCi/g;
cadmium 1 mg/kg; cesium"137 0.004 pCi/g; chromium 0.000002 mg/m3; cobalt"60 0.002 pCi/g;
europium"1^ Q.004 pCi/g; manganese 156 mg/kg; mercury 0.1 mg/kg; neptunium"237 0.002
pCi/g; nickel 130 mg/kg; potassium"40 0.033 pCi/g; technetium"99 1.8 pCi/g; thorium"230
0.003 pCi/g; uranium"234 0.003 pCi/g; uranium"235 0.007 pCi/g; uranium"238 0.001 pCi/g;
and zinc 52 mg/kg.
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DOE/OR/02-1125&D3
Record of Decision
for the K-1407-B/C Ponds
at the Oak Ridge K-25 Site
Oak Ridge, Tennessee
September 1993
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DOE/OR/02-1125&D3
Record of Decision
for the K-1407-B/C Ponds
at the Oak Ridge K-25 Site
Oak Ridge, Tennessee
September 1993
Prepared for
U.S. Department of Energy
Office of Environmental Restoration
and Waste Management
Prepared by
Radian Corporation
120 South Jefferson Circle
Oak Ridge, Tennessee 37830
under contract DE-AC05-90OR21851
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CONTENTS
PARTI. DECLARATION
SITE NAME AND LOCATION 1-3
STATEMENT OF BASIS AND PURPOSE 1-3
ASSESSMENT OF THE SITE 1-3
DESCRIPTION OF SELECTED REMEDY 1-3
STATUTORY DETERMINATIONS 1-5
APPROVALS 1-5
PART 2. DECISION SUMMARY
SITE NAME, LOCATION, AND DESCRIPTION 2-3
SITE HISTORY AND ENFORCEMENT ACTIVITIES 2-7
HIGHLIGHTS OF COMMUNITY PARTICIPATION 2-9
SCOPE AND ROLE OF THE SITE 2-10
SITE CHARACTERISTICS : 2-11
SUMMARY OF SITE RISKS 2-20
DESCRIPTION OF ALTERNATIVES 2-61
SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES 2-72
SELECTED REMEDY 2-88
STATUTORY DETERMINATIONS 2-92
EXPLANATION OF SIGNIFICANT CHANGES 2-99
PART 3. RESPONSIVENESS SUMMARY
COMMUNITY PREFERENCES 3-3
INTEGRATION OF COMMENTS 3-3
PART 4. REFERENCES
REFERENCES 4-3
D930215.4PS5J HI 09/24/93
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TABLES
2.1 Potential contaminants of concern in the K-1407-B Pond soil evaluated
quantitatively and their representative concentrations 2-21
2.2 Potential contaminants of concern in the K-1407-C Pond soil evaluated
quantitatively and their representative concentrations 2-22
2.3 Potential contaminants of concern in the K-1407-B/C Pond soils evaluated
qualitatively and their range of concentrations 2-23
2.4 Representative concentrations for K-1407-B/C Ponds potential contaminants of
concern in groundwater 2-24
2.5 Upper-bound concentrations of contaminants of concern in air for the
K-1407-B/C Ponds on-site resident 2-29
2.6 Upper-bound concentrations of contaminants of concern in K-1407-B/C Ponds
homegrown produce 2-30
2.7 Toxicity information for carcinogenic potential contaminants of concern 2-33
2.8 Toxicity information for noncarcinogenic potential contaminants of concern 2-36
2.9 Cancer risk estimates for on-site residents at the K-1407-B Pond 2-40
2.10 Hazard index estimates for on-site residents at the K-1407-B Pond 2-44
2.11 Cancer risk estimates for on-site residents at the K-1407-C Pond 2^9
2.12 Hazard index estimates for on-site residents at the K-1407-C Pond 2-53
2.13 General uncertainty factors 2-57
2.14 Site-specific uncertainty factors 2-58
2.15 Preliminary remediation goals for the K-1407-B/C Pond soils 2-63
2.16 Evaluation of alternatives for remediation of the K-1407-B/C Ponds 2-74
2.17 Comparison of compliance for each alternative for the K-1407-B/C Ponds with
ARARs and TBCs 2-78
2.18 Cost and present worth for Alternatives 2 through 6 2-87
2.19 Capital costs for Alternative 2 2-91
2.20 ARARs and TBCs for the K-1407-B/C Ponds Alternative 2 2-95
D930215 4PS5I IV 09/24/93
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FIGURES
2.1 Regional map of Oak Ridge area showing the Oak Ridge Reservation 2-4
2.2 Location of K-1407-B/C Ponds 2-5
2.3 Present land use conceptual site model for the K-1407-B/C Ponds 2-26
2.4 Future land use conceptual site model for K-1407-B/C Ponds 2-27
2.5 A comparison by scenario of total excess cancer risk from exposure to
contaminants at the K-1407-B/C Ponds 2-60
D930215.4PS5I V 09/24/93
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ACRONYMS AND INITIALISMS
ARAR applicable or relevant and appropriate requirement
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act of 1980
CFR Code of Federal Regulations
CNF Central Neutralization Facility
COC contaminant of concern
DOE U.S. Department of Energy
EPA U.S. Environmental Protection Agency
FFA Federal Facility Agreement for the Oak Ridge Reservation
FR Federal Register
FS Feasibility Study
HSWA Hazardous and Solid Waste Amendments
IRC Information Resource Center
MCL maximum contaminant level
NCP National Oil and Hazardous Substance Contingency Plan
NPDWS National Primary Drinking Water Standards
NPL National Priorities List
NRC Nuclear Regulatory Commission
NSDWS National Secondary Drinking Water Standards
O&M operation and maintenance
ORR Oak Ridge Reservation
OU operable unit
PPE personal protective equipment
PRG preliminary remediation goal
RCRA Resource Conservation and Recovery Act
RfD reference dose
RI Remedial Investigation
ROD Record of Decision
SARA Superfund Amendments and Reauthorization Act of 1986
SF slope factor
SWMU solid waste management unit
TBC to be considered
TCA Tennessee Code Annotated
TCE trichloroethene
TDEC Tennessee Department of Environment and Conservation
USAGE U.S. Army Corps of Engineers
VOC volatile organic compound
D930215.4PS51
VI
09/24/93
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PARTI. DECLARATION
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SITE NAME AND LOCATION
K-1407-B Holding Pond and K-1407-C Retention Basin (also known as K-1407-B/C Ponds)
Oak Ridge K-25 Site; K-1407 Operable Unit (OU)
Oak Ridge Reservation (ORR)
Oak Ridge, Tennessee
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected remedial action for the K-1407-B Holding
Pond and the K-1407-C Retention Basin, which are part of the K-1407 OU of the U.S.
Department of Energy (DOE) K-25 Site in Oak Ridge, Tennessee. This action was chosen in
accordance with the Comprehensive Environmental Response, Compensation, and Liability Act
of 1980 (CERCLA) as amended by the Superfund Amendments and Reauthorization Act of 1986
(SARA) and, to the extent practicable, with the National Oil and Hazardous Substance
Contingency Plan (NCP). This decision is based on the Administrative Record file for this site.
The state of Tennessee and the U.S. Environmental Protection Agency (EPA), after
review of relevant documentation, concur with the selected remedy for the K-1407-B/C Ponds.
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.
DESCRIPTION OF SELECTED REMEDY
The selected remedy addresses residual contamination in the K-1407-B/C Pond soils. The
K-1407-B/C Ponds are pan of the K-1407 OU, which is in the K-25 main plant area. Other
designated waste management units within the K-1407 OU will be evaluated under a separate
CERCLA remedial investigation (RI)/feasibility study (FS). In addition, the groundwater
contamination in the vicinity of K-1407-B/C Ponds will be addressed as part of the sitewide K-25
Groundwater OU RI/FS.
D9302IS.4PS5I 1-3 09/24/93
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This final source control action is intended to reduce the potential threats to human health
and the environment posed by residual metal, radiological, and volatile organic compound (VOC)
contamination within the K-1407-B/C Ponds.
The major components of the selected remedy for the K-1407-B/C Ponds include:
• placement of clean soil and rock fill for isolation and shielding,
• maintenance of institutional controls, and
• groundwater monitoring to assess performance of the action and to develop
information for use in reviewing the effectiveness of this remedy.
The principal threats to human health at the K-1407-B/C Ponds are to the hypothetical
future on-site resident for baseline conditions. These threats are posed primarily by I37Cs via
direct exposure to ionizing radiation, "Tc via ingestion of homegrown produce, and
trichloroethene (TCE) via groundwater ingestion. The alternative chosen for the K-1407-B/C
Ponds will provide a reduction in the potential threats from cancer risks posed by 137Cs and "Tc,
but will not address groundwater contaminants.
The threat of 137Cs, "Tc, and other soil-bound residual contaminants will be addressed
by eliminating the exposure pathways for external exposure to ionizing radiation and ingestion
of homegrown produce routes, as well as the exposure pathways for ingestion of soil, dermal
contact with soil, and inhalation of wind-generated dust. This action will isolate the residual
contaminants whose risks have been identified from the surface environment, as well as those for
which excess cancer risks cannot be quantified.
The future K-25 Groundwater OU CERCLA RI/FS will address the potential risk posed
to the hypothetical future on-site resident by TCE through groundwater ingestion and the potential
risks posed by other groundwater contaminants and groundwater pathways. Meanwhile, the
maintenance of institutional controls at the K-25 Site will preclude the completion of groundwater
pathways and the associated risks to human health.
Although engineering controls will effectively deactivate all direct exposure and soil
pathways of exposure identified in the baseline risk assessment, the continued presence of residual
soil contamination on-site represents a potential threat. The purpose of institutional controls at
the K-1407-B/C Ponds is to prevent the inadvertent exhumation of the residual soil contamination
buried under the soil cover. If at any point in the future an unconditional release of the site
becomes a possibility, DOE or its successor shall conduct a review of the remedy and current site
conditions prior to transfer of the K-25 Site from DOE or its successor to another person or
entity.
D930215.4PS5I 1-4 09/24/93
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STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the environment, complies with
federal and state requirements that are legally applicable or relevant and appropriate to the
remedial action, and is cost-effective. This remedy utilizes permanent solutions and alternative
treatment or resource recovery technologies to the maximum extent practicable. However,
because treatment of the principal threats of the site was not found to be practicable, this remedy
does not satisfy the statutory preference for treatment as a principal element. Current technology
does not offer means to effectively treat residual radiological contamination such as that found
at the K-1407-B/C Ponds site. Therefore, management of in situ residues is a more appropriate
remedy at this site.
Because this remedy will result in hazardous substances remaining on-site above health-
based levels, a review will be conducted every 5 years, beginning within 5 years after
commencement of the remedial action, to ensure that the remedy continues to provide adequate
protection of human health and the environment, as required by CERCLA 121(c).
APPROVALS
f ?
Assistant Manager for Environmental Restoration Date
and Waste Management
U.S. Department of Energy
Oak Ridge Operations
Director, DOE Oversight D\\mef:=^^ Date
State of Tennessee
Tennessee Department of Environment and Conservation
Regional Administrator Date
U.S. Environmental Protection Agency, Region IV
D930215.4PS51 1-5
09/24/93
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PART 2. DECISION SUMMARY
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SITE NAME, LOCATION, AND DESCRIPTION
The Oak Ridge K-25 Site, formerly known as the Oak Ridge Gaseous Diffusion Plant,
was built as part of the Manhattan Project during World War II and was the world's first large-
scale uranium enrichment facility. The K-2S Site is in Roane County, approximately 20 miles
west of Knoxville, Tennessee, and 10 miles southwest of the city of Oak Ridge. The facility is
accessible from the northeast and southwest by U.S. Interstate 40 to Tennessee Highway 58 and
by Blair Road from the north. It is situated in the northwest portion of the ORR at the
confluence of Poplar Creek and the Clinch River (Fig. 2.1).
The K-25 Site is bordered by five counties (Anderson, Knox, Loudon, Morgan, and
Roane) that have a combined population of greater than 500,000 (1990 census). Knoxville and
Oak Ridge are the two largest metropolitan areas within a 50-mile radius of K-25. Knoxville has
a population of approximately 165,000, and Oak Ridge has a population of approximately 27,000.
Other smaller municipalities (and their populations) lying within the surrounding counties include
Clinton (8,000), Harriman (8,000), Rockwood (6,000), Lenoir City (5,500), Kingston (4,500),
and Oliver Springs (4,000) (Energy Systems 1989).
The nearest privately owned residential properties are approximately 1.5 miles north of
the K-25 Site in the Poplar Creek/Sugar Grove Valley area. This northeast-southwest trending
valley extends for several miles in either direction from K-25 and is primarily devoted to
agricultural use. It is lightly to moderately populated. Similar population densities occur
approximately 2 miles southwest of K-25 across the Clinch River and along Highway 58 and in
the Poplar Springs community 2 miles south-southeast of K-25. Employees at K-25 constitute
an additional part-time population of approximately 2,400 people. Because of the small areal
extent of the K-1407-B/C Ponds and the relatively large distance to any local residence, regional
groundwater and the quality of groundwater used by local residents are not considered to be
affected by conditions at the ponds. There is currently no use of groundwater at the K-1407-B/C
Ponds site.
Although access to ORR and the K-25 Site is restricted to authorized personnel, deer
hunting is permitted in some areas of the reservation. Area recreational activities include
hunting, fishing, and pleasure boating on the nearby Watts Bar Lake/Clinch River waterways.
Since the land surrounding K-25 is part of the ORR, it is mostly undeveloped. However, there
are residential, industrial, recreational, and light agricultural sites in adjacent areas. Aside from
light agriculture, there is currently no commercial development of natural resources in the area.
The K-1407-B/C Ponds are in the northeast quadrant of the K-25 Site within the perimeter
fence (Fig. 2.2). The pond area is relatively flat except for the levee around the K-1407-C Pond,
D9302I5.4PSS1 2-3 09/24/93
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Map of the DOE Oak Ridge Reservation
5 0 1i JO «i 6O
MILES
TRUE
Regional Location of Y-12, ORNL, and K-25 Plant Sites
RADIAN
Source: Radian
Date: 1992
Environmental Restoration
Program
Regional map of Oak Ridge area
showing the Oak Ridge
Reservation
Fig. 2.1
D93021S.4PSS1
2-4
09/24/93
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Map of the DOE Oak Rider Rnrrvalion
K-1407-B/C PONDS
: RAILROAD
0 125 250 375
i i i i
FEEr
(SOURCE; CLOSURE PLAN KU07-B HOLDING POND
K/ER-26 - K/HS-216/R1 APRIL 1990}
RADIAN
Source: Radian
Date: 1992
Environmental Restoration
Program
Location of K-1407-B/C Ponds.
Fig. 2.2
D93021S.4PS51
2-5
09/24/9?
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and the site is readily accessible from inside the K-25 boundaries. There is no obtrusive
vegetation next to the ponds, and well-kept access ways exist. The impoundments are separated
by about 100 ft of flat terrain and by Mitchell Branch. This naturally occurring intermittent
stream, also known as the K-1700 stream, flows between the K-1407-B Pond and the K-1407-C
Pond and converges with Poplar Creek in the northwest portion of the K-25 Site (DOE 1992a).
The K-1407-B Pond is a rectangular surface impoundment approximately 400 ft long and
150 ft wide. It covers 1.3 acres and has a 2.5 million-gal storage capacity and a maximum depth
of approximately 8 ft. The K-1407-C Pond is an elongated impoundment approximately 720 ft
long and averages about 75 ft in width. It covers approximately 2.2 acres and averages about
8 ft deep. When in use, this unit had a storage volume capacity of approximately 4 million gal
(DOE 1992a).
D930213 4PS51 2-6 09/24/93
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SITE HISTORY AND ENFORCEMENT ACTIVITIES
The K-25 Site was built as part of the Manhattan Project during World War II and was
the world's first large-scale uranium enrichment facility. K-25 operated in this capacity for both
defense and nuclear energy applications from the time of its completion in 1945 until enrichment
operations ceased in 1985. The K-1407-B/C Ponds were built as settling and holding ponds
primarily for the secondary treatment of metal-laden wastes generated at K-25. The wastes
consisted of coal pile runoff water, steam plant boiler blowdown solution, steam plant fly ash,
raffinate from equipment, plating/stripping process wastes, and cleaning/decontamination and
metal-bearing wastes generated from processes at .the K-1420 metals decontamination building.
The K-1407-B/C Ponds also received purge cascade and laboratory waste solutions (Energy
Systems 1989).
The K-1407-B Pond, constructed in 1943, was primarily used for settling metal hydroxide
precipitates generated during neutralization and precipitation of metal-laden solutions treated in
the K-1407-A Neutralization Unit. It also received discharge from the K-1420 Metals
Decontamination Building and wastes from the K-1501 Steam Plant. The K-1407-C Pond,
constructed in 1973, was primarily used to store potassium hydroxide scrubber sludge generated
at K-25. It also received sludge from the K-1407-B Pond. When the K-1407-B Pond reached
maximum sludge capacity, it was dredged, and the sludge was transferred to the K-1407-C Pond
(Energy Systems 1989).
The K-1407-B/C Ponds are regulated as Resource Conservation and Recovery Act
(RCRA) interim status units and were in operation before RCRA was impacted by the Hazardous
and Solid Waste Amendments (HSWA) issued by EPA in November 1984. HSWA [Sect.
3005(j)] required that hazardous waste surface impoundments either comply with Sect.
3004(o)(l)(a) or be closed by November 1988. To satisfy the closure requirement, the discharge
of all wastes into the ponds ceased before the November 1988 mandate. DOE was in the process
of complying with RCRA regulations when the ORR was placed on the CERCLA National
Priorities List (NPL) in November 1989.
In 1985, a sampling and analysis strategy of the ponds was developed for the waste
characterization of the pond sludges and subsurface soils. RCRA constituents, as identified in
40 Code of Federal Regulations (CFR) 261 Subpart C, were characterized. Closure plans for the
removal of sludge from the K-1407-B/C Ponds were submitted to the regulators in May 1988.
Sludge removal from the K-1407-C Pond began in February 1987 and was completed in October
1988. Sludge removal from the K-1407-B Pond began in November 1988 and was completed
in August 1989. Sampling to evaluate the effectiveness of sludge removal procedures was
D93021S.4PS51 2-7 , 09/24/93
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subsequently performed and confirmed the removal of RCRA constituents and the presence of
residual radionuclide contamination in the pond soils (DOE 1992a).
Because source, special nuclear, and by-product materials as defined by the Atomic
Energy Act are not regulated under RCRA and because the ORR had been placed on the NPL,
RCRA closure activities were halted until a strategy could be developed to integrate
CERCLA/RCRA requirements. Pursuant to a tentative agreement among DOE, the Tennessee
Department of Environment and Conservation (TDEC), and EPA (Region IV), the temporary
delay in the closure of the surface impoundments was resolved by declaring that the sites would
satisfy RCRA clean closure criteria and that the CERCLA process would address radiological
contaminants at the ponds (DOE 1992b). Certification of clean closure will be completed before
remedial activities are implemented at the site.
D9302154PS51 2-8
09/24/93
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HIGHLIGHTS OF COMMUNITY PARTICIPATION
The Proposed Plan for the K-25 K-1407-B/C Ponds (DOE 1992c) was released to the
public in February 1993 by inclusion in the Administrative Record file maintained at the DOE
Information Resource Center (IRC) at 106 Broadway, Oak Ridge, Tennessee. The Notice of
Availability of the Proposed Plan was published in the Oak Ridger on February 2, 1993; in the
Knoxville News-Sentinel on January 31, 1993; and in the Roane County News on February 2,
1993.
A public comment period was held from February 3 through March 4, 1993. No public
meeting was scheduled, but an opportunity for a meeting was offered in the Notice of Availability
of the Proposed Plan for K-1407-B/C Ponds.
Responses to comments received during the public comment period would normally be
included in the Responsiveness Summary (Part 3 of this ROD); however, no public comments
were received. This decision document presents the selected remedial action for the K-25
K-1407-B/C Ponds chosen in accordance with CERCLA as amended by the SARA and, to the
extent practicable, the NCP. The remedial action decision for this site is based on the
Administrative Record.
D930215.4PS51 2-9 09/24TO
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SCOPE AND ROLE OF THE SITE
The selected alternative presented in this ROD represents the final remedial action for the
K-1407-B/C Ponds only. Source control actions addressing the remediation of other designated
waste management units within the K-1407 OU will be evaluated under a separate, future
CERCLA RI/FS(s). Groundwater contamination in the vicinity of the ponds will be addressed
as part of the sitewide K-25 Groundwater OU RJ/FS (Energy Systems 1990). These remedial
actions are intended to meet DOE's goal of reducing current threats to human health and the
environment. The selected remedy for the K-1407-B/C Ponds is consistent with planned future
remedial activities at the K-1407 OU and the K-25 Site. Data generated under post-remediation
groundwater monitoring to assess the performance of the remedial action at the K-1407-B/C
Ponds may also be used in the future K-1407 OU and K-25 Groundwater OU investigations.
The final action for the K-1407-B/C Ponds is intended to reduce the potential threats to
human health and the environment posed by residual metal, radiological, and VOC contamination
within the pond soils. The principal threats to human health at the site are to the hypothetical
future on-site resident for baseline conditions. These threats are posed primarily by 137Cs via
direct exposure to ionizing radiation, "Tc, via ingestion of homegrown produce, and TCE via
groundwater ingestion. The remedial alternative chosen for the K-1407-B/C Ponds will provide
a reduction in the potential threats from cancer risks posed by 137Cs and "Tc but will not address
groundwater contaminants.
The threat of 137Cs, "Tc, and other soil-bound residual contaminants will be addressed
by eliminating the exposure pathways for the external exposure to ionizing radiation and ingestion
of homegrown produce routes; ingestion of soil, dermal contact with soil, and inhalation of wind-
generated dust pathways will also be eliminated. This action will isolate the surface environment
from the residual contaminants for which risks have been identified and those for which excess
cancer risks cannot be quantified.
The future K-25 Groundwater OU CERCLA RI/FS will address the potential risk posed
by TCE through groundwater ingestion, as well as the potential risks posed by other groundwater
contaminants and groundwater pathways. Meanwhile, the maintenance of institutional controls
at the K-25 Site will preclude the completion of groundwater pathways and the associated risks
to human health at the K-1407-B/C Ponds.
D9302154PS51 2-10 09/24/93
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SITE CHARACTERISTICS
As settling and holding ponds for secondary treatment of metal-laden wastes generated at
K-25, the K-1407-B/C Ponds received wastes consisting of coal pile runoff water, steam plant
boiler blowdown solution, steam plant fly ash, raffinate from equipment, plating/stripping process
wastes, cleaning/decontamination and metal-bearing wastes generated from processes at the
K-1420 metals decontamination building, and purge cascade and laboratory waste solutions.
The K-1407-B/C Ponds are in the northeast quadrant of the K-25 Site, within the
perimeter fence (Fig. 2.2). The impoundments are separated by about 100 ft of flat terrain and
by Mitchell Branch. This naturally occurring intermittent stream, also known as the K-1700
stream, flows between the K-1407-B Pond and the K-1407-C Pond and converges with Poplar
Creek in the northwest portion of the K-25 Site. Mitchell Branch is the receiving stream for both
surface and groundwater discharge for the northeastern portion of K-25 and represents the main
surface water feature in the K-1407-B/C Pond area. Small portions of the ponds site, including
the south, west, and northeast sides, lie within the 100-year flood zone, including the K-1407-B
Pond area. A field survey was conducted at the K-1407-B/C Ponds site to determine the presence
of wetlands. Based on this survey, neither pond meets the criteria for wetlands as defined in the
Corps of Engineers Vfetlands Delineation Manual (U.S. Army 1987).
Soil Contamination
To comply with the original RCRA closure plans for the units, sludge removal from the
K-1407-B/C Ponds began in 1987 and was completed in 1989. In an effort to demonstrate that
all RCRA-regulated contaminants had been removed, soil verification sampling was performed.
After all visible traces of sludge were removed, soil samples were collected from the bottom of
each pond. These samples were analyzed for metals, VOCs, and radionuclides known or
suspected to be present at the site.
Analyses indicated that no metals were present above Extraction Procedure toxicity
present; technetium and uranium were found to have the highest concentrations. Because
radionuclide contamination was detected in the K-1407-B/C Ponds, a CERCLA sampling event
was conducted to gather additional data during 1989 (K-1407-C Pond) and 1990 (K-1407-B
Pond). An RI/FS was conducted for the site based on this and other pre-existing soil data and
on groundwater data previously collected from monitoring at the ponds (DOE 1992a).
Soil samples were collected to a total depth of 18 in. and analyzed at 6-in. increments (0
to 6 in., 6 to 12 in., and 12 to 18 in.) for gross alpha and beta activity, radionuclides, and
metals. Because VOCs were detected in previous sampling events and in groundwater samples
D9302I5.4PSS1 2-11 09/24/93
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from monitoring wells, analyses for organic compounds were also conducted for K-1407-B Pond
soil samples.
Analyses of soil samples collected during the 1989/1990 sampling event indicate that
radionuclide contamination exists in both K-1407-B/C Ponds. Multiple sampling points revealed
elevated alpha and beta activities. Residual metal contamination was also further defined for both
ponds, along with additional assessment of organic contamination for the K-1407-B Pond.
Although no organic constituents were found at significantly elevated levels, the VOCs 1,1,1-
trichloroethane; 1,2-dichloroethene; 1,1-dichloroethane; chloroform; tetrachloroethene; and TCE
were detected in the K-1407-B Pond soil.
The radionuclide contaminants detected in the K-1407-B/C Pond soils were 24IAm,
'"Cs^Co^Cm, 154Eu, 155Eu, 237Np, 238Pu, 239Pu, 40K, "Tc, 228Th, 230Th, 232Th, 234U, 235U,
238U, and Sr (total). However, some of these radionuclides were detected at negligible
concentrations, and *°K is a naturally occurring radionuclide. The radionuclides with the highest
average alpha activity are 238U and 234U; the predominant beta-emitting radionuclide is "Tc. The
half-lives (the amount of time required for a given radioactive species to decrease to half its initial
value due to radioactive decay) for the primary radiological contaminants of concern at the site
range from 30 years for 137Cs to 4.5 billion years for 238U.
The soil depth interval with the highest average activity for all radionuclides was the 0-
to 6-in. interval. Since soil samples have not been collected below the 18-in. zone, complete
characterization of radionuclides below this depth is not possible. However, a general reduction
of radionuclide concentrations occurs with depth. This trend of decreasing concentrations with
depth, along with other factors at the site, indicates that significant vertical or lateral migration
of contaminants from the pond soils is unlikely. This inference is supported by computer
modeling conducted during the RI/FS to assess the potential for migration of these constituents
from the pond soils.
Metals detected during sampling activities within the ponds considered potential
contaminants of concern (COCs) include As, Ba, Be, B, Cd, Cr, Co, Pb, Mn, Hg, Mo, Ni, Ag,
Sr, V, and Zn. Since background samples are not available for the K-1407-B/C Pond site, it is
difficult to eliminate detected metals by screening evaluation. Because beryllium concentrations
in the K-1407-B/C Pond soils are above guidance levels, these concentrations were compared to
background concentrations from sites with soils representative of those found at the K-1407-B/C
Ponds in the vicinity of the ORR (DOE 1992a).
The statistical analysis of these sampling results indicate that the concentrations of
beryllium in the K-1407-B/C Pond soils are comparable to the background samples to which they
were compared. Therefore, the concentrations of beryllium in the ponds are attributable to
normal background levels and not to pond operations. Based on comparison of total
D9302I5.4PS5I 2-12 09/24/93
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concentrations of RCRA-regulated metals and organics in the K-1407-B/C Pond soils to RCRA
guidance levels and on the statistical analysis that shows beryllium concentrations in the pond
soils to be consistent with background concentrations at ORR, it has been demonstrated that
RCRA-regulated metals are not present in the pond soils above regulatory criteria as a result of
pond operations. Accordingly, EPA and TDEC tentatively agreed at the June 16, 1992, Working
Group Meeting held among EPA Region IV, TDEC, and DOE at the TDEC Oversight office in
Oak Ridge, Tennessee, that the requirements have been satisfied for RCRA clean closure at the
K-1407-B/C Ponds (DOE 1992b).
The potential for migration of metal contaminants from the pond soils below the 18-in.
depth was assessed by computer modeling. Computer modeling indicates minimal migration of
metal contaminants from the K-1407-B/C Pond soils. These results, combined with the general
decrease of metals concentrations with depth, indicate a lack of significant vertical and lateral
migration of metals contaminants from the pond soils (1992a).
Since results from previous sampling events indicated that the K-1407-C Pond is not
contaminated with organic compounds, analyses for organic constituents were conducted only for
the K-1407-B Pond soil samples during the 1989/1990 sampling event. No guidance levels were
exceeded for any of the RCRA-regulated VOCs in the pond soils.
All radionuclides detected in the pond soils were included for consideration in the baseline
risk assessment. Metals detected at elevated levels during sampling activities were included in
the RI/FS baseline risk assessment without regard to the possible influence of background
concentrations. Because of the lack of background data for site contaminants, some naturally
occurring metals were included in the risk evaluation. Likewise, although the K-1407-B Pond
is not considered to be the source of organic contamination found in the groundwater at the site,
some organic compounds were evaluated in the baseline risk assessment based on their presence
in the soils.
It is estimated that there are approximately 21,000 yd3 of subgrade soils with residual
contamination at the bottom of the ponds.
Groundwater Contamination
Although groundwater remediation is beyond the scope of the remedial action proposed
by this ROD, an evaluation of groundwater contamination at the ponds site was conducted during
the RI/FS for the K-1407-B/C Ponds. The purpose of this evaluation was to determine the extent
to which contaminants from pond soils may have migrated into groundwater in the past and the
future potential for such cross-contamination. An understanding of the potential for cross-
contamination from the soil to groundwater is necessary to choose a remedial alternative
D9302I5.4PS51 2-13 09/M/93
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consistent with the long-term remedial goals for the K-1407 OU. Furthermore, this information
is necessary to choose an alternative for the K-1407-B/C Pond soils that is consistent with future
groundwater remediation at the site.
Radiochemical contamination of groundwater in the vicinity of the K-1407-B/C Ponds is
evidenced by elevated measurements of alpha and beta activity in area monitoring wells.
However, only one downgradient monitoring well at the site has been consistently contaminated.
This monitoring well, located downgradient of the K-1407-B Pond, has shown elevated beta
activity for all sampling events. Radiological contamination of groundwater at the site is
concentrated to the north and east of the K-1407-B Pond.
Based on data from monitoring wells to the west of the K-1407-B/C Ponds, alpha activity
detected in monitoring wells downgradient from the ponds may be primarily attributable to
upgradient sources. However, the elevated levels of beta activity downgradient of the K-1407-B
Pond are probably due in part to beta-emitting radionuclides (primarily "Tc) that have migrated
from the K-1407-B Pond.
Historical operations at the K-1407-B/C Ponds and the presence of radionuclides identified
in the K-1407-B/C Pond soils indicate alpha and beta emitters that might potentially be found in
the groundwater. Alpha emitters potentially present in area groundwater include 234U, 235U,
238U, 228Th, 230Th, 232Th, 238Pu, 239Pu, 24IAm, and 237Np. Potential beta emitters are "Tc, ^Sr,
137Cs, 40K, 154Eu, 234Th, and 234Pa. The predominance of 234U, 238U, and 230Th in K-1407-B/C
Pond soils indicate that one or all of these three radionuclides could be the alpha emitters detected
in the groundwater. Because it is the beta emitter with the highest level of activity in the pond
soils and it is much more mobile than the other beta-emitting radionuclides in the soil, "Tc was
believed to be the source of elevated beta activity detected in downgradient monitoring wells at
the K-1407-B Pond. Isotope-specific groundwater data for "Tc for first quarter 1992 confirmed
that this radionuclide is present in the groundwater at a sufficient concentration to account for all
beta activity detected in site monitoring wells (DOE 1992a).
Subsequent to removal of the sludge from the K-1407-B Pond, beta activity has decreased
in downgradient monitoring wells; results of groundwater sampling show steadily decreasing
levels of beta activity. Removal of the sludge from the K-1407-B Pond resulted in removal of
the primary source of "Tc that could be leached and cause cross-contamination of the
groundwater. Accordingly, beta activity in downgradient wells should continue to decrease
commensurate with contamination presently migrating from the pond soils or other upgradient
sources (DOE 1992a).
Assessment of the migration of pond contaminants to soils and groundwater beneath and
downgradient of the K-1407-B/C Ponds shows that, although a few metals have sporadically
D930215.4PS51 2-14 09/24/93
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exceeded maximum contaminant levels (MCLs) in groundwater monitoring wells at the site, none
have done so consistently. For those metals with established National Primary Drinking Water
Standards (NPDWS), only cadmium exceeded NPDWS in one monitoring well downgradient of
the K-1407-B/C Ponds for a single sampling event. No monitoring wells have exceeded
regulatory limits in filtered samples for As, Ba, Cr, Hg, Se, or Ag for any sampling event.
Computer modeling simulation of metal contaminant migration is compatible with site data,
indicating that none of the metals exhibit a significant tendency to migrate into the groundwater
from pond soils (DOE 1992a).
For metals with National Secondary Drinking Water Standards (NSDWS), manganese and
iron have exceeded guidance levels for most of the monitoring wells at the ponds for several
sampling events. Manganese has exceeded NSDWS limits for all monitoring wells for at least
one sampling event. Iron has exceeded NSDWS limits for most monitoring wells. However,
iron and manganese are present at elevated levels in monitoring wells upgradient of the
K-1407-B/C Ponds and are present at naturally elevated levels in area soils and groundwater.
The high concentrations of these metals are considered to reflect natural groundwater conditions
at the site rather than migration of contaminants from the K-1407-B/C Ponds (DOE 1992a).
Organic constituents, primarily VOCs, have been detected in both unconsolidated and
bedrock monitoring wells throughcu: the K-1407-B Pond area. TCE is the predominant VOC
in the K-1407-B/C Pond groundwater; also abundant is trans-1,2-dichloroethene. However, a
false-positive assessment, initiated in 1987 and approved by the TDEC in March 1989, concluded
that the K-1407-B Pond was not the source of halogenated organics present in the groundwater
(Haymore 1988). This conclusion is supported by analyses showing low VOC contaminant
concentrations in the K-1407-B Pond sludge and soil, the proximity of K-1407-B Pond to
numerous Solid Waste Management Units (SWMUs), and hydrogeologic conditions at the site
(Geraghty & Miller, 1989a). Infiltration of groundwater contaminated with VOCs may also
occur by upgradient flow from the bedrock zone (Forstrom 1990). For the most part,
groundwater in the vicinity of the K-1407-C Pond has not been found to be contaminated with
VOCs.
Although guidance values for alpha activity are exceeded in some of the K-1407-B/C Pond
monitoring wells, activity has not been detected at levels considered to pose a risk to human
health. Therefore, alpha-emitting radionuclides are not considered to be COCs in groundwater
at the site. Of the beta emitters present in the groundwater, "Tc is believed to be the
predominant contributor to beta activity.
D930215.4PS51 2-15 09/M/93
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Hydrogeology characteristics and groundwater pathways of migration
Analysis of the hydraulic relationship between groundwater in the bedrock zone and the
unconsolidated zone at the K-1407-B Pond reveals that hydraulic heads can be greater in bedrock
than in the unconsolidated zone (Forstrom 1990). The higher piezometric levels in the bedrock
zone indicate confined or semiconfined flow conditions within the bedrock and the potential for
upward groundwater flow from the bedrock to the unconsolidated zone. This condition is
important to migration of contamination at the K-1407-B Pond. Upward flow can retard the
downward migration of dissolved contaminants from the unconsolidated zone to the bedrock zone.
Conversely, contaminants could be introduced from the bedrock zone into the unconsolidated
zone, as indicated for organic contaminants at the site.
Water has been continually present in the K-1407-B Pond since discharge operations
ceased prior to 1988. Comparison of the surveyed ground elevation at the bottom of K-1407-B
Pond with seasonal water table elevations recorded for monitoring wells in the vicinity of the
pond shows that the bottom of the K-1407-B Pond is several feet below the groundwater table,
indicating that groundwater in the unconsolidated zone is discharging directly into the surface
impoundment. Conversely, the K-1407-C Pond is situated several feet above the water table.
Because the residual contamination in the K-1407-B/C Ponds could be subject to leaching
by infiltration of meteoric waters and because the K-1407-B Pond's bottom is further affected by
groundwater flow through the unit, groundwater transport of contamination is considered a
potential pathway of migration at the site. Differing hydrogeological conditions at the K-1407-B
and K-1407-C Ponds represent different implications for contaminant transport from the ponds.
Analysis of the migration of contamination at the K-1407-B Pond is complicated by the existence
of contaminant sources upgradient of the unit and by upward groundwater flow from the bedrock
zone into the unconsolidated zone.
The mobility of radionuclides and metals in groundwater within the K-1407-B/C Pond
soils is related to the properties of the individual constituents and to the properties of the soils
in which they are found. Since the pH of groundwater in K-1407-B monitoring wells is neutral
to only slightly acidic, the solubilities of the radionuclides and metals are generally expected to
be moderate. Soil and groundwater characteristics at the site are not expected to promote
migration of most constituents.
Technetium-99 represents an exception to this general trend. While cationic substances
are strongly adsorbed by the clays typically found in area soils, the ability of "Tc to form
complexes and behave in an anionic nature allows it to migrate relatively freely. The high
potential for the migration of "Tc is indicated by the elevated levels detected in monitoring wells
downgradient of the K-1407-B Pond.
D930215.4PS51 2-16 09/24/93
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Soil pathways of migration for baseline conditions
The soil pathway for contaminant migration at the K-1407-B/C Ponds site is closely
associated with the groundwater pathway. The clay residuum found at the site typically has a low
hydraulic conductivity and a relatively high capacity for adsorption of cations and filtering of
particulates (Lee, et al., 1988; Baes, et al., 1984). These characteristics indicate that the majority
of the radionuclides and metals present at the units would tend to be bound in the soil.
Since the probable mode of migration of these constituents is leaching by infiltration of
surface water, movement is expected to be minimal. With the exception of "Tc, which is highly
mobile in the soil column, the migration of most of the metals and radionuclides is likely to be
minimal. Surface runoff is possible for the K-1407-B/C Ponds site but is expected to be
attenuated by site conditions. Because surface water runoff at the ponds is limited, the associated
transport of soil is also limited. Furthermore, vegetation at the site inhibits soil runoff during
storm events. Thus, the physicochemical properties of the COCs and of the surrounding soil
suggests that overall transport of contaminants from the soil will be low.
Surface water pathways of migration for baseline conditions
Analyses of sediment samples from Mitchell Branch have shown it to be contaminated
with metals, radionuclides, and organic compounds indicating historical discharge of contaminants
into the stream (Ashwood 1986). Since K-25 encompasses many sites of contaminant discharge,
it is not possible to determine the extent to which historical discharges from the K-1407-B/C
Ponds may have contributed to the contamination of Mitchell Branch. Current site conditions and
operations preclude significant erosion of contaminated soils or direct discharge from the ponds
into Mitchell Branch.
Analysis of soil and groundwater data indicates that COCs would not migrate to Mitchell
Branch from the pond soils. Although it cannot be completely eliminated as a possible pathway
of migration, groundwater from these units is not likely to be a measurable contributor to surface
water contamination because of the low concentrations of contaminants in the groundwater
migrating from the units. Therefore, based on current site conditions and operations, the
contaminants found in the K-1407-B/C Pond soils do not represent a significant potential for
contamination of surface waters (i.e., Mitchell Branch) at the site.
Air pathways of migration for baseline conditions
Suspension of contaminated soil as airborne fugitive dust is considered a potential
migration and exposure pathway for alpha- and beta-emitting radionuclides and toxic metals. The
potential volatilization of organics from the soil surface is not considered a major pathway of
D930215.4PS5I 2-17 09/24/93
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migration since only low concentrations of organic contaminants were detected in K-1407-B Pond
soil.
Current conditions at the K-1407-B/C Ponds are not conducive to the airborne migration
of contamination. Site conditions, such as the presence of standing water in the K-1407-B Pond
and vegetation at both units, would serve to inhibit the formation of significant amounts of wind-
generated dust. However, these conditions are relatively ephemeral and largely dependent on
levels of precipitation. Extended drought conditions could drastically alter site conditions.
Therefore, generation of airborne constituents found at the pond sites should be considered a
potential migration pathway for contamination from the site. Contaminant concentrations in air
and associated risks to human health in the baseline risk assessment were based on fate and
transport modeling.
Biota pathways of migration for baseline conditions
The ingestion and transportation of contaminated plants to off-site areas by herbivores
represents a potential migration route for site-related contaminants. Since vegetation is the basic
foundation of the terrestrial food chain, accumulation of site-related contaminants in plants can
transport contaminants throughout the system. Plants growing in contaminated soils can
accumulate radionuclide, metal, and organic contaminants. This would lead to the ingestion and
assimilation of contaminated media by small herbivores and subsequent transport of these
contaminants off-site. Similarly, aquatic biota in Mitchell Branch could accumulate contaminants
directly from the water or by ingesting contaminated prey.
Due to the low concentrations of organic contaminants detected in the K-1407-B Pond's
soils, air-to-leaf transfer is not expected to be a major pathway of vegetative contamination.
Ingestion of contaminated vegetation by herbivores or other links in the food chain is considered
negligible.
Exposure routes for baseline conditions
Current exposure routes to the general public are limited by institutional controls.
Although operations at the K-1407-B/C Ponds have ceased, it is conceivable that an on-site
worker could go onto these sites. There is also a potential that employees in the K-25 vicinity
could be exposed to wind-generated dust contamination from the ponds. In addition, travelers
on a public road outside the facility boundary could also be exposed to wind-generated dust. If
institutional controls were removed from the K-25 Site in the future, human receptors entering
the site could be adversely affected by existing contamination. The greatest potential risk would
exist for the on-site resident.
M30215.4PS5I 2-18 09/24/93
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Potential exposure pathways for both the general plant employee and the on-site worker
are ingestion of, dermal contact with, and inhalation of wind-generated dust. The general plant
employee is additionally considered to be exposed to radiation in dust; the on-site worker is
additionally considered to be exposed to ionizing radiation.
Assuming that contaminant concentrations in the soil remain constant, the potential
pathways affecting the on-site resident include ingestion of and dermal contact with contaminated
soil, external exposure to ionizing radiation, and inhalation of wind-generated dust. Because
groundwater in the vicinity of K-25 is sufficient to support household activities, it is also assumed
that the on-site resident could be exposed to contaminants in groundwater via ingestion, dermal
contact during bathing, and inhalation of volatiles during bathing. It is also assumed that the on-
site resident could consume contaminated homegrown vegetables.
Site conditions affecting remedial action
The K-1407-B/C Ponds are readily accessible from inside the K-25 Site area and amenable
to remedial construction activities at the site. The emplacement of rock fill to a level above the
normal water table should eliminate any complications that standing water in the K-1407-B Pond
might present. However, if water in the pond does not equilibrate quickly enough with the water
table to allow continued construction activity, water will be pumped from the pond to the K-25
Central Neutralization Facility (CNF) and processed.
D930215.4PS5I 2-19 09/24/93
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SUMMARY OF SITE RISKS
Human health risks
As part of the CERCLA RI/FS process, a human health risk assessment was performed
for the K-1407-B/C Ponds following the Risk Assessment Guidance for Superfund (EPA 1989a)
and the Superfund Exposure Assessment Manual (EPA 1988a). The complete baseline risk
assessment is contained in Sect. 5 of the Remedial Investigation/Feasibility Study (RI/FS) for the
K-1407-B/C Ponds K-25 Site, Oak Ridge, Tennessee, DOE/OR-1012&D3 (DOE 1992a). Risks
from contamination exposure from the K-1407-B and K-1407-C Ponds were evaluated separately;
however, because of the physical similarity and proximity of the sites, the evaluations used
similar assumptions.
Data evaluation
Sampling data were obtained as part of earlier studies to characterize the nature and extent
of contamination present in the various media at the K-1407-B/C Ponds. EPA-certified
laboratory methods were followed during the analysis of soil samples from the ponds. Although
the data were not initially independently validated, laboratory personnel conducted a data review
before the risk assessor received the data. Additionally, the risk assessment personnel scrutinized
the data before using them in the risk assessment. A representative portion of the data was
validated at a later date to confirm the usefulness of the data for use in the baseline risk
assessment. Based on this evaluation, not all laboratory data were appropriate for use in a
quantitative manner. Instead, some of the data were incorporated into a qualitative assessment
or eliminated from the assessment process altogether. Validation of data for use in the risk
assessment was conducted in accordance with the procedures outlined in the Risk Assessment
Guidance for Superfund, Volume I: Human Health Evaluation Manual (EPA 1989b) and the
Remedial Facility Investigation Guidance Volume I (EPA 1989c).
Contaminants of concern
As a result of the data evaluation process, a list of potential COCs in soil was developed,
which was then divided into those contaminants to be quantitatively evaluated and those to be
qualitatively evaluated in the baseline risk assessment. The concentrations for COCs evaluated
quantitatively for the K-1407-B and K-1407-C pond soils are shown in Tables 2.1 and 2.2,
respectively. The concentrations for COCs evaluated qualitatively are shown in Table 2.3. The
risk from exposure to some contaminants detected in the pond soils cannot be quantified because
no current EPA-approved slope factor (SF) or reference dose (RfD) is available; these
contaminants were evaluated qualitatively.
D9302I5.4PS5I 2-20
09/24/93
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Table 2.1. Potential contaminants of concern in the K-1407-B Pond soil evaluated quantitatively
and their representative concentrations
Analyte
Organics (mg/kg)
1,2-Dichloroethene (total)
1,1,1 -Trichloroethane
Chloroform
Tetrachloroethene
Trichloroethene
Metals (mg/kg)
Arsenic
Barium
Beryllium
Boron
Cadmium
Chromium
Manganese
Mercury
Molybdenum
Nickel
Vanadium
Zinc
Radionuclides (pCi/g)
Americium-241
Cesium- 137
Neptunium-237
Plutonium-238
Plutonium-239
Potassium-40
Technetium-99
Thorium-228
Thorium-230
Thorium-232
Uranium-234
Uranium-235
Uranium-238
Frequency
of detection
3/40
1/40
4/40
8/40
11/40
6/17
17/17
17/17
10/17
17/17
17/17
17/17
4/8
1/17
17/17
17/17
17/17
19/19
48/48
48/49
48/49
48/49
49/49
49/49
44/45
48/49
48/49
49/49
48/49
49/49
Range of detected
concentrations
0.027 - 0.033
0.001 - 0.001
0.006 - 0.024
0.005 - 0.069
0.009 - 0.130
6.8 - 32.0
33.0 - 250.0
0.37 - 1.8
2.0 - 19.0
0.82 - 4.1
26.0 - 240.0
86.0 - 1,800.0
2.9 - 13.0
2.3 - 2.3
20.0 - 1,100.0
14.0 - 43.0
26.0 - 98.0
-0.51 - 0.32
0.02 - 62.10
-0.04 - 15.12
-5.94 - 0.21
-1.97 -25.65
5.94 - 35.10
2.05 - 1,107.0
-99.90 - 43.20
0.27 - 432.0
-0.59 - 22.68
1.27 - 4,050.0
-0.05 - 180.9
0.68 - 26,190.0
Representative
concentration*
0.033
0.001b
0.024
0.069
0.130
16.2
133.1
1.3
9.9
3.2
114.6
867;.5
6.6
2.3b
324.2
35.4
72.5
0.13
6.42
1.97
0.40
3.24
18.64
1,239.6
5.08
72.12
3.53
470.5
20.52
1,674.2
'Except where indicated, all representative concentrations are either the maximum detected concentration or the 95%
upper confidence limit on the arithmetical average of 0- to 6-in. samples, whichever is lower.
bOnly detected value.
D9302I5.4PSSI
2-21
09/24/93
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Table 2.2. Potential contaminants of concern in the K-1407-C Pond soil evaluated quantitatively
and their representative concentrations
Analyte Frequency of detection
Metals (mg/kg)
Arsenic
Barium
Beryllium
Boron
Cadmium
Chromium
Manganese
Mercury
Molybdenum
Nickel
Silver
Vanadium
Zinc
Radionuclides (pCi/g)
Americium-241
Cesium- 137
Cobalt-60
Curium-244
Europium- 154
Neptunium-237
Plutonium-238
Plutonium-239
Potassium-40
Technetium-99
Uranium-234
Uranium-235
Uranium-238
6/16
16/16
16/16
8/16
12/16
16/16
16/16
12/17
8/16
16/16
1/16
16/16
16/16
78/78
78/78
75/75
25/25
1/1
78/78
78/78
78/78
76/76
78/78
78/78
78/78
78/78
Range of detected concentrations
7.0 - 30.0
59.0 - 160.0
0.48 - 1.6
3.5 - 34.0
0.57 - 7.4
25.0 - 160.0
550.0 - 2,700.0
1.1 - 29.0
1.0 -4.3
20.0 - 1,400.0
0.9 -0.9
28.0 -61.0
37.0 - 120.0
-1.08 - 32.40
0.24 - 178.2
-0.20 - 0.35
-0.35 - 0.06
2.13 -2.13
4.6 X JO'3 - 143.1
-2.43 - 16.20
2.7 x lO'3 - 162.0
3.24 - 23.76
0.04 - 4,320.0
1.32 -2,673.0
0.06 - 62.10
0.81 - 1,620.0
Representative
concentration1
20.7
116.5
1.0
13.7
2.3
86.0
1,563.7
10.4
3.7
507.4
0.9b
50.2
87.9
4.04
22.28
0.04
-0.01
2.13"
13.12
1.56
20.48
11.77
586.8
348.0
12.39
186.6
'Except where indicated, all representative concentrations are either the maximum detected concentration or the 95%
upper confidence limit on the arithmetical average of 0- to 6-in. samples, whichever is lower.
"Only detected vatoe.
D9302I54PS5J
2-22
09/24/93
-------
Table 2.3. Potential contaminants of concern in the K-1407-B/C Pond soils evaluated
qualitatively and their range of concentrations
4 , , _ -. . Range of detected
Analyte Frequency of detecnon concentrations'
K-J407-B Pond Organics (mg/kg)
1,1-Dichloroethane 1/40 0.003 - 0.003b
K-J407-B Pond Metals (mg/kg)
Cobalt 17/17 2.5-26.0
Lead 17/17 6.6 - 58.0
Strontium 17/17 8.2 - 38.0
K-1407-CPond Metals (mg/kg)
Cobalt 16/16 8.5 - 29.0
Lead 15/16 16.0 - 59.0
Strontium 16/16 8.4 - 64.0
K-1407-B Pond Radionuclides (pCi/g)
Europium-155 3/3 1.11 - 7.83
'Reported concentrations represent the samples taken from the top 6 in. of soil only.
bOnly detected value.
The potential for migration of soil contaminants to groundwater at the ponds site made
the evaluation of risks posed by exposure to groundwater pathways necessary. By considering
groundwater contamination in the risk assessment, the risk contribution of soil contamination to
the groundwater pathway was evaluated.
Radioisotopes are present in the soils of both ponds, and a potential exists for migration
to groundwater. The risk associated with exposure to beta activity in K-1407-B Pond's
groundwater was determined quantitatively by assuming that the source of all beta activity is "Tc,
a mobile beta-emitting radioisotope that has been found in K-1407-B Pond soil. The complete
list of COCs for groundwater and their concentrations is found in Table 2.4.
Exposure assessment
The original primary contamination source in the K-1407-B/C Ponds was sludge. Prior
to sludge removal in 1988, contamination had apparently transferred to the underlying soil;
consequently, the soil is now a potential contamination source. Currently, the contaminated clay
soil of the ponds is exposed to atmospheric conditions, and some vegetation exists to prevent
erosion. Although precipitation is occasionally retained in K-1407-C Pond, the bottom of the
pond is usually dry. The K-1407-B Pond typically contains water because it is below the local
water table. But because the K-1407-B Pond could become dry during periods of drought and
would then represent a potential for wind-generated dust, the pond was assumed to be dry for the
D930215.4PS51 2-23 09/24/93
-------
Table 2.4. Representative concentrations for K-1407-B/C Ponds potential contaminants of concern
in groundwater
Analyte
Organic* (mg/L)
1 , 1 -Dichloroethane
1,2-Dichloroethene (total)
1,1,1-Trichloroethane
Chloroform
Tetrachloroethene
Trichloroethene
Metals (mg/L)
Boron
Strontium
Frequency of Range of detected
detection concentrations
K-1407-B Pond
14/14
13/13
13/13
5/13
12/12
13/13
17/17
16/16
0.11-1.0
0.05-1.9
0.031-0.29
0.0008-0.006
0.038-0.93
0.87-10.0
0.13-0.21
0.27-0.65
Representative
concentration8
1.0
1.9
0.29
0.006
0.93
10.0
0.21
0.65
Radionuclides (pCi/L)
Beta Activity as technetium-99 NA -32.0-1137.6 1137.6
K-1407-C Pond
Metals (mg/L)
Arsenic
Cadmium
Cobalt
Manganese
Mercury
Molybdenum
Strontium
10/17
8/21
10/20
30/30
2/17
2/20
20/20
0.005-0.009
0.003-0.017
0.0078-0.21
0.014-33.0
0.003-0.0051
0.012-0.013
0.055-0.27
0.009
0.017
0.21
33.0
0.005
0.013
0.27
"Maximum concentrations detected in monitoring wells nearest the ponds.
NA=Not Applicable
2-24
D930215.4PS5I Z-Z^ 09/24/93
-------
purpose of the risk assessment. This assumption likely resulted in an overestirnation of actual
risks from wind-generated dust.
Figure 2.3 illustrates the site conceptual model that represents baseline exposure pathways
related to contamination at the ponds, including potentially exposed populations, exposure
scenarios, transport media, and routes of exposure. Since the K-1407-B/C Ponds are within the
perimeter security fence, no recreational activity occurs there (i.e., no boating, swimming,
fishing). The ponds are not fenced within the main plant area, but are posted; access by plant
employees and visitors is restricted. Although operations at the ponds have been curtailed, it is
assumed that on-site workers will be exposed to risks while conducting occasional site
inspections. Potential also exists for general K-25 Site employees at some distance from the
ponds to be exposed to airborne contaminants originating from the pond soils. Although no
residents live along Blair Road in proximity to the K-1407-B/C Ponds, this public road is just
outside the K-25 Site boundary approximately 700 ft from the ponds. Travelers on the road may
potentially be exposed to wind-transported paniculate contamination from the ponds. In
summary, the receptors who under current conditions may be exposed to K-1407-B/C Ponds
contamination are an on-site worker, a general plant employee working in other areas of the K-25
Site, and an individual traveling on Blair Road.
If institutional controls were removed from the K-25 Site, future receptors could be
adversely affected by existing contamination. Because residential land use is most often
associated with the greatest exposures, future exposure was evaluated within the context of a
residential scenario. The environmental media responsible for transport and the potential
exposure pathways considered in the residential scenario are shown in the future land use site
conceptual model in Fig. 2.4, Environmental concentrations were assumed to be constant for the
baseline risk assessment (i.e., concentrations were not reduced by loss due to removal processes
such as volatilization, leaching, and biodegradation). Thus, exposure concentrations were based
on 100% of the measured or estimated concentrations in air, soil, and groundwater.
The on-site resident scenario assumes that the K-1407-B Pond is dewatered, and all
activities related with residency take place in the soils at the bottom of the pond. Therefore, the
surface water pathway for the K-1407-B Pond was not considered in the baseline risk assessment.
Because the groundwater in the vicinity of the K-1407-B/C Ponds is sufficient to support
household activities, it was assumed that on-site residents would use groundwater for domestic
purposes.
Because all soil exposure pathways considered in the risk assessment involve exposure to
surface soil only, the representative soil concentrations for metals and radionuclides were
determined from samples taken at a depth of 0 to 6 in. Furthermore, soil concentrations for most
D9302I5.4PS51 2-25 09/24/93
-------
PRIMARY
SOURCES
PRIMARY
RELEASE
MECHANISM
SECONDARY
SOURCES
SECONDARY
RELEASE
MECHANISM
PATHWAY
RECEPTOR
Infiltration/
Percolation
|k-
Soil
/
\
to
K>
O\
Completed Pathway
Potential Pathway
Eliminated Pathway
General BWr
ExpoM* On-Sfte Plant Road
Route Worfcar Employee Tfavator
External
Surface
Water and
Sediments
tnftmmitftn
nlyMOOfi
Inhalation
Dermal
External
Ingerton
Inhalation
Dwmal
External
E
E
E
•
E
E
E
E
E
E
E
E
E
E
E
E
E
E ,
E
E
E
E
E
E
Groundwater
Ingeston
Inhalation
Dermal
External
E
E
E
E
E
E
E
E
E
E
E
E
RADIAN
Source: Energy Systems
Date: 1991
Present land use conceptual site
model for the K-1407-B/C Ponds.
Environmental Restoration Program
Fig. 2.3
-------
PRIMARY
SOURCES
PRIMARY
RELEASE
MECHAMSU
SECONDARY
SOURCES
SECONDARY
RELEASE
MECHANISM
PATHWAY
HbCfcPIUH
OrvSte
K>
RADIAN
Source: Energy Systems
Date: 1991
Environmental Restoration Program
Future land use conceptual site
model for the K-1407-B/C Ponds.
Fig. 2.4
-------
metals and radionuclides tend to decrease with depth. Conversely, VOCs have the potential for
volatization, and concentrations detected in the K-1407-B Pond soil increase with depth.
Therefore, the maximum concentration of organic contaminants, regardless of depth, was used
as the representative concentration.
The 95% upper confidence limit on the arithmetical average was chosen as the
representative concentrations for each metal and radionuclide in soil. If the computed upper-
bound confidence limit was greater than the maximum detected concentration, then the maximum
detected value was used as the exposure concentration. Transport equations were used to estimate
the contaminant concentration in air. Elemental soil-to-plant transfer coefficients developed by
Baes et al. (1984) for the edible portions of plants were used to estimate the upper-bound
concentration of contaminants in plants. The transfer of organics to plants from soil was
calculated using the regression equation developed by Travis and Arms (1988). There are five
volatile potential COCs present in K-1407-B Pond's groundwater that could be inhaled by the
resident while showering. Indoor air concentrations were estimated using an upper-bound default
volatilization constant of 0.5 L/m3 (EPA 1989d). The representative concentrations of
contaminants in each medium are shown in Tables 2.1 through 2.6.
The scenario for the on-site worker assumes that an employee will be on-site for 1 h,
eight times a year. The intake of contaminants was calculated using a soil ingestion rate of 50
mg/day, a body surface area of 0.394 m2/day (arm, hands, and face), and an inhalation rate of
20 m3/day (EPA 1989a). The variables used in each exposure equation were derived from
standard intake rates, skin surface areas, and adherence factors. Variables relating to exposure
frequency and duration were derived from knowledge of site conditions and assumptions
regarding receptor activity. Approximately 50% of the year, the wind direction is southeast.
Therefore, it was assumed that the general plant employee would be exposed to wind-generated
dust half of the time, or 4 h/day, 5 days/week, 50 weeks/year for 25 years (EPA 1989a).
It was assumed that the resident would be exposed to site-related contaminants
350 days/year for 30 years. Exposure from all pathways except external radiation were divided
into two sets of assumptions. First, a 6-year exposure duration was evaluated for young children,
which accounts for receptors with high intake rates relative to low body weights. Second, a 24-
year exposure duration was assumed for older children and adults. For example, for the soil
ingestion pathway, a child ingestion rate (200 mg/day) and body weight (15 kg) was assumed for
6 years, while an adult ingestion rate (100 mg/day) and body weight (70 kg) was assumed for
24 years (EPA 1989a). The formulas used to calculate risks are provided in the baseline risk
assessment of the Remedial Investigation/Feasibility Study for the K-1407-B/C Ponds, K-25 Site
Oak Ridge, Tennessee (DOE 1992a; pp. 5-31 through 5-34, pp. 5-40 through 5-43, and pp. 5-49
through 5-56).
D930215.4PS5I 2-28 09/24/93
-------
Table 2.5. Upper-bound concentrations of contaminants of concern in air
for the K-1407-B/C Ponds on-site resident
Analyte
Organics (mg/it?)
1,1-Dichloroe thane
1 ,2-Dichloroethene (total)
1,1,1-Trichloroethane
Chloroform
TetrachJoroethene
Trichloroethene
Metals (mg/m3)
Arsenic
Barium
Beryllium
Boron
Cadmium
Chromium
Manganese
Mercury
Molybdenum
Nickel
Silver
Vanadium
Zinc
Radionuclides (pCi/m3)
Americium-241
K-1407-B Pdnd
9.6 x 10'12
6.1 x 10'11
3.2 x 10-"
7.7 x 10'1'
2.2 x lO'10
2.8 x 10'10
5.2 x 10'8
4.3 x lO'7
4.2 x 10'9
3.2 x 10'8
1.0 x 10'8
3.7 x ID'7
2.8 x 10'6
2.1 x 10'8
7.4 x 10'9
1.0 x 10-*
a
1.1 x lO'7
2.3 x lO'7
4.3 x 1C'7
K-1407-C Pond
a
a
a
a
a
a
6.6 x 10'8
3.7 x 10'7
3.4 x lO'9
4.4 x 10'8
7.4 x 10'9
2.8 x lO'7
5.0 X 10'6
3.3 x lO'8
1.2 x 10'8
1.6 x 10-6
2.9 x lO'9
1.6 x 10'7
2.8 x lO'7
1.3 x 10'5
'These data are not available.
D9302JS.4PSS1 2-29 09/M/93
-------
Table 2.6. Upper-bound concentrations of contaminants of concern in K-1407-B/C Ponds
homegrown produce"
Analyte
Orgonics (mg/kg)
1 , 1 -Dichloroethane
1 ,2-Dichloroethene
1,1,1-Trichloroethane
Chloroform
Tetrachloroethene
Trichloroethene
Metals (mg/kg)
Arsenic
Barium
Beryllium
Boron
Cadmium
Chromium
Manganese
Mercury
Molybdenum
Nickel
Silver
Vanadium
Zinc
Radionuclides (pd/g)
Americium-24 1
Cesium- 137
Cobalt-60
Curium-244
Europium- 154
Neptunium-237
Plutonium-238
Plutonium-239
Potassium-40
Technetium-99
Thorium-228
Thorium-230
Thorium-232
Uptake c -
coefficient" g ^
3.57 1.79
5.41 1.48
1.39 2.5
2.81 1.97
1.22 2.6
1.63 2.38
0.006
0.015
0.0015
2.0
0.15
0.0045
0.050
0.20
0.060
0.060
0.10
0.003
0.90
2.5 x 10-4
0.030
0.007
1.5 x lO'5
0.004
0.010
4.5 x 10'5
4.5 x ID'5
0.55
1.5
8.5 x 10-5
8.5 x ID'5
8.5 x lO"5
RME
K-1407-B
produce
0.011
0.178
0.001
0.067
0.084
0.212
0.097
1.996
0.002
19.874
0.478
0.516
43.374
1.316
0.086
19.454
d
0.106
65.277
3.4 x 10'5
.19
d
_d
d
0.02
1.8 x 10'5
1.4 x lO"4
10.25
1,859.5
4.3 x 10^
6 X 10-3
3 x 10-4
concentration
K-1407-C
produce
d
d
_d
d
d
_d
0.124
1.748
0.002
27.488
0.346
0.387
78.185
2.072
0.224
30.444
0.090
0.151
79.150
1 x 10'3
.67
3 x 10"4
-1.2 x IQ-7
9 x lO'3
0.13
7 x 10'5
1 x 10-3
6.47
880.2
d
d
d
D9302154PS5I
2-30
09/24/93
-------
Ihble 2.6 (continued)
Analyte
Uranium-234
Uranium-235
Uranium-238
Uptake . v t ~"
coefficient" "* *™
0.004
0.004
0.004
RME concentration
K-1407-B
produce
1.88
0.08
6.70
K-1407-C
produce
1.39
0.05
0.75
'Produce concentrations derived from the soil concentrations given in Table 2.1 and 2.2.
^Source: Transfer coefficients for metals and radionuclides taken from C.F. Baes III, R.D. Sharp, A.L.Sjoreen, and R.W.
Shor, A Review and Analysis of Parameters for Assessing Transport of Environmentally Released Radionuclides through
Agriculture, ORNL-5786, Martin Marietta Energy Systems, Inc., Oak Ridge National Laboratory, September 1984.
'Source: Log Kow values for all organics from EPA, SuperfundPublic Health Evaluation Manual, EPA/540/1-86/060,
Office of Emergency and Remedial Response, Washington D.C., October 1986.
dThese data are not available.
D9302I5.4PSS1
2-31 ' 09/74/93
-------
Toxicity assessment
The toxicity information for the carcinogenic and noncarcinogenic COCs is summarized
in Tables 2.7 and 2.8, respectively.
Risk characterization
Cancer risk from exposure to contamination is expressed as excess cancer risk—that is,
the incidence of cancer incurred in addition to normally expected rates of cancer development.
An excess cancer risk of 1 x 10"6 indicates one person in 1,000,000 is predicted to incur cancer
from exposure to this contamination level. Excess cancer risks falling between 1 x 10"6 and
1 x 10~* are within the EPA range of concern and require close scrutiny; cancer risks greater
than 1 x lO'4 are considered unacceptable by the EPA (EPA 1989b). Excess cancer risk is
estimated by multiplying intake by the contaminant-specific cancer SF published by EPA. SFs
used in the evaluation of risk from exposure to contaminants in K-1407-B and K-1407-C soil are
listed in Table 2.7. SFs have not been derived for several potential COCs. These contaminants
may contribute to carcinogenic effects from exposure to the soil, but their effect cannot be
quantified.
Noncarcinogenic effects are evaluated by comparing the exposure experienced over a
specified time period with an RfD derived for a similar exposure period. RfDs available for the
COCs present in K-1407-B and K-1407-C soil are given in Table 2.8. The ratio of the exposure
dose to the RfD is called the hazard quotient. A hazard quotient greater than one indicates that
there may be concern for potential noncarcinogenic health effects; however, the level of concern
does not increase linearly as the hazard quotient approaches or exceeds one. The sum of all
hazard quotients for all contaminants for a given exposure pathway is the hazard index for that
pathway. SFs and RfDs have been derived from human epidemiological studies or animal studies
to which uncertainty factors have been applied. These uncertainty factors help ensure that the
SFs and RfDs will not underestimate the potential for adverse health effects.
For the on-site worker at the K-1407-B Pond, the excess cancer risks posed by exposure
to wind-generated dust via ingestion, dermal contact, and inhalation are well below the range of
concern. The total pathway risk, however, is 2 x 10"6 for external exposure to ionizing
radiation, slightly above the lower limit EPA range of concern of 1 x 10"6. Lead and strontium,
also found at the site, may contribute to the carcinogenic effects from exposure to airborne soil
contaminants (especially lead, given its classification as a probable B2 human carcinogen), but
an SF is not available for lead. Although an SF exists for radioactive strontium, there are no
isotope-specific data for strontium; consequently, the carcinogenic effects from exposure to these
contaminants were not quantified. No adverse noncarcinogenic health effects are indicated for
exposure to any specific contaminant at the K-1407-B Pond for the on-site worker.
D9302I5.4PS51 2-32 09'24/93
-------
Table 2.7. Toxicity information for carcinogenic potential contaminants of concern
Ingestion pathway
Chemical
Arsenic6- c
Bariumb- c
Beryllium0
Boronb- c
Cadmiumb> c
Chromiumb- C(VI)
Cobaltb' c
Leadb' c
Manganese*1- c
Mercuryb- c
Molybdenum1*- c
Nickel"- c
Silver0
Strontium"' °
\fcnadiumb> °
Zincb- °
Chloroform"
1,1-Dichloroethane"
1,2-Dichloroethene (total)"
Tetrachloroethene"
1,1,1-TrichIoroethane"
Trichloroethene"- c
Americium-24l"- °
Cesium- 1 37"- c
Cobalt-60°
Curium-244°
Europium- 154°
Neptunium-237"- c
Plutonium-238"' °
Plutonium-239b- c
Potassium-40b' c
Technetium-99"- c
Thorium-228"
Thorium-230b
Tliorium-232b
Uranium-234b- c
Uranium-235b' c
Uranium-238b- c
SFa
(mg/kg-d)-1
(pCi)"1
1.7E+00
d
4.3E-KX)
d
d
d
d
d
d
d
d
d
d
d
d
d
6.1 X 10'3
d
d
5.1 x 10'2
d
1.1 x i
-------
Table 2.7 (continued)
Inhalation Pathway
Chemical
Arsenic1"' c
Barium1"' c
Beryllium'
Boronb' c
Cadmiumb- c
Chromium6' c
Cobalt1"' c
Lead"- c
Manganese1"' c
Mercury*"' c
Molybdenum1"' c
Nickelb'c
Silverc
Strontium1"' c
Vanadium6' c
Zinc"' c
Chloroform1"
l,l-Dichloroethaneb
1 ,2-Dichloroethene(total)b
Tetrachloroetheneb
l,l,l-Trichloroethaneb
Trichloroetheneb' c
Americium-241b'c
Cesium- 137b- c
Cobalt-60c
Curium-244c
Europium- 154C
Neptunium-237b' c
Plutonium-238b- c
Plutonium-239b' c
Potassium-40b- c
Technetium-99b' c
Thorium-228b
Thorium-230b
Thorium-232b
Uranium-234b- c
Uranium-235b- c
Uranium-238b' c
SFa
(mg/kg-d)-1
(pCi)'1
5.0 x 101
d
8.4
d
6.1
4.1 x 101
d
d
d
d
d
8.4 x 10'1
d
d
d
d
8.1 X 10'2
d
d
1.82 x 10'3
d
1.7 x 10'2
4.0 x ID'8
1.9 x 10'n
1.6 x ID'10
2.7 x 10'8
1.4 x 10'10
3.6 x 10'8
4.2 x 10'8
4.1 x 10'8
7.6 x 10'12
8.3 x 10'12
7.7 x 10'8
3.1 x 10'8
3.1 x lO'8
2.7 x 10'8
2.5 x 10'8
2.4 x 10'8
Weight of
evidence
A
d
B2
d
Bl
A
d
D
D
d
d
A
d
d
d
d
B2
d
d
B2
d
B2
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
Type of
cancer
Respiratory tract
d
Lung
d
Respiratory tract
Lung
d
d
d
d
d
Respiratory tract
d
d
d
d
Liver
d
d
Leukemia and Liver
d
Lung
Many types'
Many types'
Many types'
Many types'
Many types'
Many types'
Many types'
Many types'
Many types'
Many types'
Many types'
Many types'
Many types'
Many types'
Many types'
Many types'
SF basis/
SF source8
'various/IRIS
d
Inhalation/IRIS
d
Occupational/
IRIS
Occupational/
IRIS
d
IRIS
IRIS
IRIS
IRIS
Occupational/
IRIS
d
d
d
d
IRIS
d
d
Inhalation/IRIS
d
Inhalation/
HEAST
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
D9302154PSS1
2-34
09/24/93
-------
Table 2.7 (continued)
External radiation exposure
Chemical
Americium-241biC
Cesium- 1 3 7b-c
Cobalt-60c
Curium-244c
Europium- 154C
Neptunium-237b- c
Plutonium-238b- c
Plutonium-239b> c
Potassium-40b> c
Technetium-99b> c
Thorium-228b
Thorium-230b
Thorium-232b
Uranium-234b' c
Uranium-235b- c
Uranium-238b- c
SFa
(pCi/m2/yr)"'
1.6 x lO'12
3.4 x I0'"f
1.3 x lO'10
5.8 x 10'14
6.8 x lO'"
1.8 x 10'12
6.1 x KT4
2.6 x 10'14
7.8 x JO'12
3.4 x NT17
1.6 x lO'13
5.9 x lO'14
4.6 x.10'14
5.7 x lO'14
9.6 x 10'12
4.6 x 10'14
Weight of
evidence
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
Type of
cancer
Many types'
Many types'
Many types'
Many types'
Many types'
Many types'
Many types'
Many types'
Many types'
Many types'
Many types'
Many types'
Many types'
Many types'
Many types'
Many types'
SF basis/
SF source8
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
•Based on IRIS, July 1991, or HEAST, January 1991.
bContaminant found in the K-1407-B Pond.
'Contaminant found in the K-1407-C Pond.
dToxicity information not available.
'The type of cancer is dependent upon the organ or organs exposed.
'External slope factor for cesium-137 daughter product, barium-137m.
HEAST = Health Effects Assessment Summary Table
IRIS = Integrated Risk Information System
SF = Slope factor
A = sufficient evidence of carcinogenicity in humans; human carcinogen
B1 = limited evidence of carcinogenicity in humans
B2 = sufficient evidence of carcinogenicity in animals with inadequate or lack of evidence in humans
D = not classifiable as to human carcinogenicity (lack of or no evidence)
D9302I5.4PS51
2-35
09/24/93
-------
Table 2.8. Toxicity information for noncarcinogenic potential contaminants of concern
KJ
Ingestion pathway
Chemical
Arsenica'b
Bariuma'b
Beryllium6
Borona'b
Cadmiuma'b
Chromiuma'b(VI)
Cobalta'b
Lead1"
Manganese8'6
Mercury"'"
Molybdenuma'b
Nickel''b
Silverb
Strontium0
Vanadiuma'b
Zinca'b
RfD
(mg/kgnl)
1.0X 10 3
7.0 x 102
5.0 X 10°
9.0 X 102
5.0 x 104
1.0 x 10 3
5.0 X 103
c
c
1.0 x 10'
3.0 x 104
4.0 x 103
2.0 X 102
3.0 x 103
C
7.0 x 10°
2.0 X 10 '
Confidence
level
High
c
Low
c
High
High
Low
c
c
Medium
c
c
c
Medium
c
Low
Medium
Critical effect
Keratosis,
hyperpigmentation
c
c
Testicular lesions
Proteinuria
Hepatotoxicity
nephrotoxicity dermatitis
c
c
Neural tissue damage
Kidney effects
Changes in biochemical
indices
c
Argyria
c
c
Hyperactivity, decreased
body weight, death at high
doses
RfD basis/
RfD source
Occupational/IRIS
IRIS
Intratracheal
Instillation/IRIS
IRIS
Water/IRIS
Food/IRIS
Water/IRIS
c
c
Water/IRIS
IRIS
IRIS
IRIS
Oral/IRIS
C
Water/IRIS
Gavage/IRIS
UF
100
3
100
100
10
500
1
1000
1
100
2
100
100
MF
1
1
1
1
1
1
c
c
1
1
3
1
C
1
1
-------
Table 2.8 (continued)
10
1
Chemical
Chloroform"-1*
1,1-Dichloroethane*
1 ,2-Dichloroethene(tot)a
Tetrachloroethene"
1,1,1 -Trichloroethane"
Trichloroethene"
RfD
(mg/kg-d)
1.0 x 10 2
1.0 x 10"'
2.0 x 10"'
1.00 x 10"'
9.0 x 102
Under review
Ingestion
Confidence
level
c
c
Low
Medium
Medium
c
pathway (continued)
Critical
effect
Liver lesions
None
Increased serum
alkaline phosphate
Hepatotoxicity
Hepatotoxicity
Ventricular fibrillation
RfD basis/
RfD source
IRIS
Inhalation/IRIS
Water/IRIS
Gavage/IRIS
Inhalation/IRIS
c
UF
1000
1000
100
1000
1000
MF
1
1
1
1
c
Inhalation pathway
Chemical
Arsenic*-1*
Barium"-1*
Beryllium1"
Borona>b
Cadmiumiib
Chromium"-1*
Cobalt'-"
Leadab
Manganese"-1*
Mercury3-1*
Molybdenuma-b
Nickel8-6
Silver6
RfD
(mg/Tcg-d)
c '
1.4 x 10"4
c
c
c
5.7 x lO'7
c
c
1.14 x 10^
8.57 x 10s
c
c
c
Confidence
level
c
c
c
c
c
c
c
c
c
c
c
c
c
Critical
effect
c
Fetotoxicity
c
c
c
Respiratory effects
c
c
Respiratory symptoms and
psychomotor disturbances
Neurotoxicity
c
c
c
RfD basis/
RfD source
c
IRIS
c
c
c
IRIS
c
c
Inhalation/IRIS
Inhalation/HEAST
c
c
c
UF
1000
300
900
30
MF
c
c
c
c
c
c
c
c
c
-------
Table 2.8 (continued)
N»
i
1>J
00
Inhalation pathway
Chemical
Strontiuma'b
Vanadiuma'b
Zinca'b
Chloroforma-b
1 , 1 -Dichloroethane"
1 ,2-Dichloroethene(tot)'
Tetrachloroethene3
1,1,1 -Trichloroethane'
Trichloroethene1
RfD
(mg/kgKl)
c
c
c
1.0 x 10'
c
C
2.86 x 10 '
c
Confidence
level
c
c
c
c
c
c
c
c
Critical
effect
c
c
c
Kidney damage
c
c
Hepatotoxicity
c
RfD basis/
RfD source
c
c
c
Inhalation/IRIS
c
c
Inhalation/IRIS
c
UF MF
c
c
c
1000
c
c
1000
c
"Contaminant found in K-I407-B Pond.
bContaminant found in K-I407-C Pond.
Toxicity information not available.
HEAST = Health Effects Assessment Summary Table
IRIS = Integrated Risk Information System
MF = Modifying factor
RfD = Reference dose
UF = Uncertainty factor
-------
The excess cancer risk from exposure to contaminants at the K-1407-C Pond for the
on-site worker are similar to the risks for the K-1407-B Pond on-site worker. Again, the excess
cancer risk posed by exposure to wind-generated dust via the ingestion, dermal contact, and
inhalation pathways are well below the range of concern. The total pathway risk from external
exposure to ionizing radiation (4 x 10"6), however, slightly exceeds the lower limit of concern
(1 x 10"6). This risk is predominately due to external exposure to ionizing radiation from 137Cs.
Health risks to the general plant employee are well below the level of concern for both
ponds.
The Blair Road receptor may be exposed to contaminants transported off-she by the wind.
Potential exposure routes for this receptor are the same as those considered for the general plant
employee. However, the Blair Road receptor would be exposed to windborne contamination for
a much shorter period of time for two reasons: (1) the wind blows northeast toward Blair Road
approximately 25 % of the time, while the wind blows southwest toward the plant approximately
50% of the time; and (2) the only receptors would be people who occasionally drive or
infrequently walk along the road. Of these potential receptors, the person who travels Blair Road
every day to and from work is likely to be exposed for the greatest period, assumed to be only
minutes a day for a maximum duration of 30 years (the upper-bound length of time spent at one
residence). Therefore, the exposure frequency and duration expected for the Blair Road traveler
is a small fraction of that considered in the evaluation of general plant employee exposure.
Consequently, because the risks to the general plant employee were well below levels of concern,
the risk to the Blair Road receptor is also expected to be well below levels of concern.
The hypothetical on-site resident at the K-1407-B Pond could be exposed to both soil and
groundwater contamination. Residential exposure would result in the highest risk of all land uses
considered, so greater detail is provided on chemical-specific and pathway-specific risks. Table
2.9 lists all chemical-specific carcinogenic risks, total pathway risk, and total exposure risk
estimates. Every pathway evaluated indicated a risk greater than 1 x 10"6; the highest risks are
due to external exposure to ionizing radiation, ingestion of groundwater (as drinking water), and
ingestion of homegrown produce. The excess cancer risks from exposure to 238U, arsenic, and
234U in surface soil dominate the ingestion, dermal contact, and inhalation pathways. Cesium-137
is a major contributor to external exposure to ionizing radiation, while "Tc dominates the
ingestion pathway risk for homegrown produce. Exposure to TCE dominates the risks associated
with ingestion of groundwater and dermal contact and inhalation during showering.
Exposure to noncarcinogenic COCs by the on-site resident at the K-1407-B Pond may
result in adverse health effects from soil-related pathways and from ingestion of contaminated
groundwater (Table 2.10). Exposure to chromium controls the inhalation pathway while mercury
D93021S.4PS51
2-39 09/24/93
-------
Table 2.9. Cancer risk estimates for on-site residents at the K-1407-B Pond
Analyte
Exposure Route:
Chloroform
Tetrachloroethene
Trichloroethene
Arsenic
Beryllium
Americium-241
Cesium- 137
Neptunium-237
Plutonium-238
Plutonium-239
Potassium-40
Technetium-99
Thorium-228
Thorium-230
Thorium-232
Uranium-234
Uranium-235
Uranium-238
Exposure Route:
Chloroform
RME
(mg/kg)
(pCi/kg)
Ingestion of soil
2.4 x IO'2
6.9 x 10'2
1.30 x 10'1
1.62 x 10'
1.32
1.34 x IO2
6.42 x 10}
1.97 x IO3
4.01 x IO2
3.24 x IO3
1.86 x IO4
1.24 x IO6
5.08 x IO3
7.21 x IO4
3.53 x IO3
4.71 x IO5
2.05 x IO4
1.67 x IO6
Dermal contact with
2.4 x 10 2
Tetrachloroethene 6.9 x IO"2
Trichloroethene
Arsenic
Beryllium
1.3 x 10'1
1.62 x IO1
1.32
Intake
(mg/kg-d)
(pCi)
3.77 x 10-"
1.08 x IO"7
2.04 x IO-7
2.54 x 10'5
2.07 x IO'6
1.69 x IO2
8.09 x IO3
2.48 x IO3
5.05 x IO2
4.08 x IO3
2.35 x IO4
1.56 x IO6
6.4 x IO3
9.09 x IO4
4.45 x IO3
5.93 x 10s
2.59 x IO4
2.11 x IO6
soil
8.71 x 10 8
2.50 x 10'7
4.72 x IO"7
5.88 x JO'6
4.78 x IQ-7
SF
(mg/kg.d)-l
(pCi)-l
6.1 x 10 3
5.1 x I0'2
1.1 x 10"2
1.70
4.30
3.1 x 10"10
2.8 x IO'"
2.7 x lO'10
2.8 x 10 lo
3.1 x IO'10
I.I x 10'11
1.3 x JO'12
1.5 x 10-"
2.4 x 10""
2.2 x 10'"
1.4 x 10'10
1.3 x lO'10
1.3 x 10'10
6.10 x I0"3
5.10 x I0'2
1.10 x |0'2
1.70
4.30
Weight of
Evidence
B2
B2
B2
A
Bl
A
A
A
A
A
A
A
A
A
A
A
A
A
B2
B2
B2
A
Bl
Type of cancer
Liver
Liver
Liver
Skin
a
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Liver
Liver
Liver
Skin
a
SF basis/SF
source
Gavage/IRIS
Gavage/IRIS
Gavage/IRIS
a
Intratracheal
Instillation/IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
Gavage/IRIS
Gavage/IRIS
Gavage/IRIS
a
Intratracheal
Instillation/IRIS
Chemical- Total
specific pathway
risk risk
2 x 10-'°
6 x lO'9
2 x IO-9
4 x 10"'
9x 10"6
5 x 10 8
2 x 10"7
7 x 10'7
1 x 10'7
1 x IO"7
3 x IO"7
2 x ID'6
1 x 10'7
2 x 10'6
1 x 1Q-7
8 x 10"5
3 x 10'6
3 x 10'4
4 x 10"4
5 x lO'10
1 x 10'8
5 x JO'9
1 x I0"5
2 x 10'6
1 x IO'5
-------
Table 2.9 (continued)
1
Analyte
RME
(mg/kg)
(pCi/kg)
Intake
(mg/kg-d)
(pCi)
SF
(mg/kg-d)-l
(pCi)-l
Weight of
Evidence
Type of cancer
SF basis/SF
source
Chemical- Total
specific pathway
risk risk
Exposure Route: Inhalation of wind-generated dust
K»
^
a
1
Chloroform
Tetrach loroethene
Trichloroethene
Arsenic
Beryllium
Cadmium
Chromium
Nickel
Americium-241
Cesium- 137
Neptunium-237
Plutonium-238
Plutonium-239
Potassium-40
Technetium-99
Thorium-228
Thorium-230
Thorium-232
Uranium-234
Uranium-235
Uranium-238
Exposure Route:
Americium-241
Cesium- 137
Neptunium-237
Plutonium-238
Plutonium-239
7.68 x 10'9
2.21 x IO"7
4.16 x IO'7
5.2 x 10'8
4.2 x 10'9
1.0 x 10'8
3.7 x 10'7
1.0 x 10*
4.3 x 10'7
2.1 x I0'5
6.3 x 10*
1.3 x 10*
1.0 x I0"5
6.0 x JO'5
4.0 x 10'3
1.6x 10-'
2.3 x 10 4
I.I x I0'5
1.5 x 10J
6.6 x 10'5
5.4 x 10'3
External exposure
1.34x IO2
6.42 x IO3
1.97 x IO3
4.01 x IO2
3.24 x IO3
2.74 x 10'9
7.89 x 10'8
1.49 x IO'7
1.86 x 10'8
1.5 x IO'9
3.57 x IO-9
1.32 x 10'7
3.57 x 10'7
1.16 x lO'1
5.64
1.69
3.49 x 10'1
2.69
1.61 x IO1
1.08 x IO3
4.30
6.18 x 10'
2.96
4.03 x IO2
1.77 x 10'
1.45 x IO3
to soil radiation
6.17 x IO5
2.95 x IO7
9.05 x IO6
1.85 x IO6
1.49 x IO7
8.10 x I0'2
1.82 x 10°
1.70 x IO'2
5.0 x IO1
8.40
6.10
4.1 x IO1
8.4 x 10'1
4.0 x IO'8
1.9 x 10'"
3.6 x IO'8
4.2 x IO'8
4.1 x 10'8
7.6 x ID'12
8.3 x I0'n
7.7 x 10'8
3.1 x 10'8
3.1 x IO'8
2.7 x lO'8
2.5 x JO'8
2.4 x lO'8
l.6x 10'12
3.4 x 10-"
1.8 x IO'12
6.1 x IO'14
2.6 x 10'14
B2
B2
B2
A
B2
Bl
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
a
Leukemia
Lung
Respiratory tract
Lung
a
a
a
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
a
Inhalation/IRIS
Inhalation/
HEAST
Various/IRIS
Inhalation/IRIS
a
a
a
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
2 x 10-'°
1 x 10-'°
3 x ID'9
9 x 10'7
1 x IO'8
2 x 10'8
5 x 10*
3 x IO'7
5 x IO'9
1 x lO'10
6 x 10'8
1 x 10'8
1 x IO'7
1 x 10-'°
9 x 10'9
3 x lO'7
2 x 10*
9 x 10'8
1 x 10'5
4 x 10'7
3 x 10'5
6 x I0"5
1 x 10*
1 x lO'3
2 x 10'5
1 x JO'7
4 x IO'7
-------
S
§
3
ut
Analyte
Potassium-40
Technetium-99
Thorium-228
Thorium-230
Thorium-232
Uranium-234
Uranium-235
Uranium-238
Exposure Route:
Chloroform
K> Tetrachloroethene
*; Trichloroethene
r^J
Technetium-99
RME
(mg/kg)
(pCi/kg)
1.86 x IO4
1.24 x IO6
5.08 x IO3
7.21 x IO4
3.53 x IO3
4.71 x IO5
2.05 x IO4
1.67 x IO6
Intake
(mg/kg-d)
(pCi)
8.58 x IO7
5.71 x IO9
2.34 x IO7
3.32 x IO8
1.62 x IO7
2.17 x IO9
9.45 x IO7
7.71 x IO9
Table
SF
(mg/kg-d)-!
(pCi)-l
7.8 x IO'4
3.4 x IO'17
1.6 x IO'13
5.9 x lO'14
4.6 x IO'14
5.7 x 10'14
9.6 x 10'12
4.6 x lO'14
2.9 (continued)
Weight of
Evidence
A
A
A
A
A
A
A
A
Type of cancer
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
SF basis/SF
source
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
Chemical- Total
specific pathway
risk risk
7 x IO-4
2 x IO-7
4 x 10'*
2 x IO-5
7 x ID'7
1 x I0'4
9 x IO4
4 x IO-4
4 x IO'3 '
Ingestion of groundwater
6fi v in~3
.u x iu
9.3 x IO'1
1.0 x IO1
1.14 x IO3
1.2 x IO'4
1.86 x IO'2
2.0 x 10'1
2.28 x IO1
6.1 x I0'3
5.1 x I0'2
I.I x IO2
1.3 x ID'1
B2
B2
B2
A
Liver
Liver
Liver
Many types
Gavage/IRIS
Gavage/IRIS
Gavage/IRIS
IRIS
7 x IO'7
9 x IO4
2 x IO3
3 x 10 5
Exposure Route: Dermal contact with groundwater while showering
Chloroform 6.0 x IO'3 2.34 x IO'7 6 I x IO'3
Tetrachloroethene 9.3 x IO'1 3.63 x 10 5 5 | x IO'2
Trichloroethene 1.0 x IO1 3.9 x IO4 | | x
I0':
B2
B2
B2
Liver
Liver
Liver
0.003 mg/m3
0.47 mg/m3
5.0 mg/m3
4.9 x ID'6
7.7 x lO'4
8.2 x 10'3
8.1 x 10 2
1.82 x IO0
1.7 x 10'2
B2
B2
B2
a
Leukemia
Lung
Exposure Route: Inhalation of volatiles while showering
Chloroform
Tetrachloroethene
Trichloroethene
Chloroform
Tetrachloroethene
Trichloroethene
Arsenic
Gavage/IRFS I x IO'9
Gavage/IRIS 2 x IO'6
Gavage/IRIS 4 x 10 6
—* 3 x lO'7
Inhalation/IRIS I x |Q6
Inhalation/ 1 x 10"4
HEAST
ion of homeg
6.7 x IO-2
8.4 x 10'2
2.1 x 10-'
9.7 x |Q-2
;rown produce
2.73 x I0'5
3.42 x 10'5
8.55 x 10 5
3.95 x lO'5
6.1 x IO3
5.1 x I0'2
1.1 x 1Q-2
1.70
B2
B2
B2
A
Liver
Liver
Liver
Skin
Gavage/IRIS
Gavage/IRIS
Gavage/IRIS
a
2 x IO-7
6 x 10 7
2 x 10 7
2 x ID'6
3 x l
-------
Table 2.9 (continued)
1
N)
b
Analyte
Beryllium
Americium-241
Cesium- 137
Neptunium-237
Plutonium-238
Plutonium-239
Potassium-40
Technetium-99
Thorium-228
Thorium-230
Thorium-232
Uranium-234
Uranium-235
Uranium-238
RME
(mg/kg)
(pCi/kg)
2.0 x 10'3
3.4 x IO'2
1.93 x IO2
2.0 x IO1
1.8 x I0'2
1.4 x IO'1
1.03 x IO4
1.86x IO6
4.3 x 1C'1
6.00
3.0 x 10'1
1.88 x IO3
8.2 x IO1
6.7 x IO3
Intake
(mg/kg-d)
(pCi)
8.14 x 10'7
1.43 x 10'
8.1 1 x IO4
8.4 x IO3
7.56
5.88 x IO1
4.31 x IO6
7.81 x IO8
1.81 x IO2
2.52 x IO3
1.26 x IO2
7.9 x 10s
3.44 x IO4
2.81 x IO6
SF
(mg/kg-d)- 1
(pCi)-l
4.30
3.1 x 10'10
2.8 x lO'"
2.7 x IO'10
2.8 x lO'10
3.1 x IO'10
1.1 x 10-"
1.3 x 10'12
1.5 x ID'"
2.4 x IO01
2.2 x 10'"
1.4 x 10'10
1.3 x lO'10
1.3 x IO'10
Weight of
Evidence
Bl
A
A
A
A
A
A
A
A
A
A
A
A
A
Type of cancer
a
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
. Many types
Many types
Many types
SF basis/SF
source
Intratracheal
Instillation/IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
Chemical-
specific
risk
9 x W7
4 x 10'9
2 x I0'6
2 x 10'6
2 x IO'9
2 x 10'9
5 x 10"5
1 x I0'3
3 x ID'9
6 x IO'8
3 x 10'9
1 x IO'4
4 x 10'6
4 x IO"4
Total
pathway
risk
Total exposure risk
2 x 10'3
1 x 10
'2
'These data are either not available or not applicable.
HEAST = Health Effect Assessment Summary Tables
IRIS = Integrated Risk Information System
RME = Reasonable maximum exposure
SF = Slope factor
A = sufficient evidence of carcinogenicity in humans; human carcinogen
Bl = limited evidence of carcinogenicity in humans
D2 = sufficient evidence of carcinogenicity in animals with inadequate or lack of evidence in humans
D = not classifiable as to human carcinogenicity (lack of or no evidence)
-------
Table 2.10. Hazard index estimates for on-site residents at the K-1407-B Pond
K)
Analyte
RME
(mg/kg)
Intake
(mg/kg-d)
RfD
(mg/kg-d)
CL
Critical effect
RfD
basis/source
UF
MF
Hazard
quotient
Pathway
hazard
index
Exposure Route: Ingestion of soil
II Diphlnm^thsinp
, i -L/icnior ocinonc
1,2-Dichloroethene
1,1,1 -Trichloroethane
Chloroform
Tetrachloroethene
Arsenic
Barium
Beryllium
Boron
Cadmium
Chromium
Manganese
Mercury
Molybdenum
Nickel
Vanadium
Zinc
3.0 x 10°
3.3 x IO'2
1.0 x I0'3
2.4 x I0'2
6.9 x lO'2
1.62 x 10'
1.33 x 102
1.32
9.94
3.19
1.15 x I02
8.67 x 102
6.58
2.30
3.24 x I02
3.54 x I01
7.25 x I01
Exposure Route: Dermal contact with
1,1-Dichloroethane
1,2-Dichloroethene
1,1,1 -Trichloroethane
Chloroform
3.0 x 10°
3.3 x I0'2
1.0 x I0'3
2.4 x IO'2
4.26 x 10'8
4.69 x IO'7
1.42 x IO'8
3.41 x 10'7
9.80 x 10'7
2.3 x IO'4
1.89 x 10°
1.87 x IO-5
1.41 x IO-4
4.52 x 10'5
1.63 x 10°
1.23 x 10'2
9.34 x IO'5
3.27 x I0"5
4.6 x ID'3
5.03 x IO4
1.03 x IO0
soil
6.09 x IO'7
6.70 x 10'6
2.03 x ID'7
4.87 x I0'6
1.0 x 10"'
2.0 x 10'1
9.0 x 10'2
1.0 x IO'2
1.0 x 10-'
1.0 x 10°
7.0 x 10'2
5.0 x 10 3
9.0 x 10 2
1.0 x IO3
5.0 x 10 3
1.0 x 10"'
3.0 x 10 4
4.0 x |0'3
2.0 x I0'2
7.0 x 10°
2.0 x |Q-'
1.0 x lO'1
2.0 x 10-'
9.0 x |0'2
1.0 x IO'2
a
Low
Med
a
Med
High
a
Low
a
High
Low
Med
a
a
a
Low
Med
a
Low
Med
a
None
Incr. serum alk.
phos.
Hepatotoxicity
a
Hepatotoxicity
Keratosis/
hyperpigment.
a
a
a
Proteinuria
Hepatotox/
nephrotox
Neural tissue
damage
Neurotoxicity
a
a
a
Hyperactivity
None
Incr. serum alk.
phos.
Hepatotoxicity
a
Inhalation/IRIS
Water/IRIS
Inhalation/IRIS
IRIS
Gavage/IRIS
Occupational/
IRIS
IRIS
IRIS
Intratrac.
instill./IRIS
FoooVIRIS
Water/IRIS
Water/IRIS
__a
a
IRIS
Water/IRIS
Gavage/IRIS
Inhalation/IRIS
Water/IRIS
Inhalation/IRIS
IRIS
1000
1000
1000
1000
1000
100
3
100
100
10
500
1
10
a
100
100
100
1000
1000
1000
1000
]
1
1
1
1
1
1
1
1
1
1
1
1
1
3
I
1
1
1
1
1
4.26 x I0'7
2.34 x 10 6
1.58 x lO'7
3.41 x IO"5
9.80 x IO-6
2.3 x 10'1
2.7 x |Q-2
3.74 x 10°
1.57 x 10'3
4.52 x W2
3.26 x JO'1
1.23 x IO'1
3.11 x IO1
8.17 x 10°
2.3 x ID'1
7.19 x I0'2
5.15 x |Q-3
6.09 x 10 6
3.35 x IO'5
2.26 x I0'6
4.87 x IO"4
1.38
-------
8
s
3
o
Analyte
Tetrachloroethene
Arsenic
Barium
Beryllium
Boron
Cadmium
Chromium
Manganese
to
i.
*-" Mercury
Molybdenum
Nickel
Vanadium
Zinc
Table 2.10 (continued)
RME
(mg/kg)
6.9 x I0'2
1.62 x 10"
1.33 x IO2
1.32
9.94
3.19
1.15 x I02
8.67 x 102
6.58
2.30
3.24 x I02
3.54 x 10'
7.25 x I01
Intake
(mg/kg-d)
1.40 x
3.29 x
io-5
io-4
2.7 x IO'3
2.67 x
2.02 x
6.47 x
2.33 x
l.76x
1.34 x
4.67 x
6.58 x
7.19 x
1.47 x
io-5
io-4
io-5
io-3
io-2
io-4
io-5
1C"3
IO4
io-3
Rft)
(mg/kg-d)
1.0 x
1.0 x
7.0 x
5.0 x
9.0 x
1.0 x
5.0 x
1.0 x
3.0 x
4.0 x
2.0 x
7.0 x
2.0 x
io-1
io-3
io-2
io-3
io-2
io-3
io-3
io-1
io-4
10°
lO'2
io-3
io-1
CL
Med
High
a
Low
a
High
Low
Med
a
a
a
Low
Med
Critical effect
Hepatotoxicity
Keratosis/
hyperpigment
a
a
a
Proteinuria
Hepatotox/
nephrotox
Neural tissue
damage
Neurotoxicity
a
a
a
Hyperactivity
RfD
basis/source
Gavage/IRIS
Occupational/
IRIS
IRIS
IRIS
Intratrac.
instill./IRIS
Food/I RIS
Water/I RIS
Water/IRIS
a
a
IRIS
Water/IRIS
Gavage/IRIS
UF
1000
100
3
100
100
10
500
1
10
a
100
100
100
., . Pathway
.._ Hazard . /
MF .. . hazard
quotient . .
M index
1 1.40 x
1 3.29 x
1 3.86 x
1 5.35 x
1 2.24 x
1 6.47 x
1 4.65 x
1 1.76 x
1 4.45 x
1 I.l7x
3 3.29 x
I 1.03 x
1 7.36 x
io-4
io-1
io-2
io-3
io-3
io-2
10-'
10-'
io-1
io-2
io-1
io-1
io-3
1.98
Exposure Route: Inhalation of wind-generated dust
1,1-Dichloroethane
1,1,1-Trichloroethane
Barium
Chromium
Manganese
Mercury
9.6 x \0'n
3.2 x I0'12
4.3 x IO"7
3.7 x 10'7
2.8 x IQ-6
2.1 x JO'8
3.21 x
1.07 x
1.44 x
1.24 x
9.35 x
7.01 x
io-"
io-"
lO'6
IO-6
IO"6
10'8
1.0 x
2.86
1.43
5.7 x
1.14
8.57
io-1
x IO'1
x IO'4
IO7
x IO"4
x 10'5
a
a
a
a
a
a
Kidney damage
Hepatotoxicity
Fetotoxicity
Respiratory
effects
Respiratory/
psychomotor
Neurotoxicity
Inhalation/lRIS
Inhalation/IRIS
IRIS
IRIS
Inhalation/IRIS
Inhalation/
HEAST
1000
1000
1000
a
900
30
— • 3.2 x
— • 3.7 x
— a 1.0 x
— a 2.2
— " 8.2 x
— • 8.2 x
,0-.o
10-"
io-2
io-2
io-4
2.3
-------
Table 2.10 (continued)
K)
Analyte
RME
(mg/kg)
Intake
(mg/kg-d)
RfD
(mg/kg-d)
CL
Critical effect
RfD
basis/source
UF
, , . Pathway
.._ Hazard , /
MF . , hazard
quotient . .
index
Exposure Route: Ingestion of groundwater
1,1-Dichloroelhane
1,2-Dichloroethene
1,1,1-Trichloroethane
Chloroform
Tetrachloroethene
Boron
1.00
1.90
2.9 x
6.0 x
9.3 x
2.1 x
to-'
io-3
ID"1
10-'
Exposure Route: Dermal contact with
1,1-Dichloroethane
1 ,2-Dichloroethene
1,1,1 -Trichloroethane
Chloroform
Tetrachloroethene
Boron
1.00
1.90
2.9 x
6.0 x
9.3 x
2.1 x
10'
io-3
io-1
lo-1
1.55 x IO'1
2.95 x lO'1
4.5 x IO'2
9.3 x IO'4
1.44 x IO'1
3.26 x 10'2
groundwater
2.2 x IO4
4.18 x I0'4
6.38 x 10'5
1.32 x 10 6
2.05 x 10 4
4.62 x lO'5
1.0 x
2.0 x
9.0 x
1.0 x
1.0 x
9.0 x
1.0 x
2.0 x
9.0 x
1.0 x
1.0 X
9.0 x
io-1
10'
io-2
io-2
io-1
io-2
io-1
io-1
io-2
io-2
io-1
10 2
a
Low
Med
a
Med
a
a
Low
Med
a
Med
a
None
Incr. serum alk.
phos.
Hepatotoxicity
a
Hepatotoxicity
a
None
Incr. serum alk.
phos.
Hepatotoxicity
a
Hepatotoxicity
a
Inhalation/IRIS
Water/IRIS
Inhalation/IRIS
IRIS
Gavage/IRIS
Intratrac.
instill./IRIS
Inhalation/IRIS
Water/IRIS
Inhalation/IRIS
IRIS
Gavage/IRIS
Intratrac.
instill./IRIS
1000
1000
1000
1000
1000
100
1000
1000
1000
1000
1000
100
1.55
1.47
4.99
9.3 x
1.44
3.62
2.2 x
2.09
7.09
1.32
2.05
5.13
Exposure Route: Inhalation of volatiles while showering
1,1-Dichloroethane
1,1,1-Trichloroethane
0.5 mg/m3
0.15
mg/m3
8.2 x I0'4
2.47 x IO'4
1.0 x
2.86
10'
x 10-'
a
a
Kidney damage
Hepatotoxicity
Inhalation/IRIS
Inhalation/IRIS
1000
1000
x IO'1
io-2
x IO'1
5.42
IO3
x 10°
x 10-"
x IO4
x 10 3
x 10'4
7.69 x I0'3
— a 8.0 x I0'3
— " 8.6 x IO4
8.86 x IO'3
Exposure Route: Ingestion of homegrown produce
1,1-Dichloroethane
1,2-Dichloroethene
1,1,1 -Trichloroethane
Chloroform
1.10
1.79
1.39
6.74
x IO'2
X 10°
x 10 3
x 10'2
3.42 x IO5
5.57 x IO'4
4.32 x IO'6
2.10 x IO4
1.0 X
2.0 x
9.0 x
1.0 x
io-1
io-1
10 2
IO2
a
Low
Med
a
None
Incr. serum alk.
phos.
Hepatotoxicity
a
Inhalation/IRIS
Water/IRIS
Inhalation/IRIS
IRIS
1000
1000
1000
1000
1 3.42
1 2.78
1 4.80
1 2.10
x IO4
x lO'3
x IO5
x IO'2
-------
Table 2.10 (continued)
Analyte
Tetrachloroethene
Arsenic
Barium
Beryllium
Boron
Cadmium
Chromium
Manganese
Mercury
Molybdenum
Nickel
Vanadium
Zinc
Total pathway hazard
RME
(mg/kg)
8.42
9.7 x
2.00
2.0 x
1.99
4.78
5.16
4.34
1.32
x I0'2
io-2
io-3
x IO1
x 10-'
x IO'1
x IO1
8.6 x JO"2
1.95
1.06
6.53
index
x IO1
x IO'1
x IO1
Intake
(mg/kg-d)
2.62
3.02
6.21
6.22
6.18
1.49
1.6 x
1.35
4.09
2.67
6.05
x IO'4
x IO'4
x IO-3
x IO"6
x IO-2
x 10°
io-3
x IO'1
x 10
x 10'4
x 10'2
3.3 x 10-"
2.03
x 10"'
RfD
(mg/kg-d)
1.0 x IO'1
1.0 x ID'3
7.0 x IO'2
5.0 x 10°
9.0 x IO'2
1.0 x 10°
5.0 x IO'3
1.0 x IO'1
3.0 x IO"1
4.0 x IO'3
2.0 x 10'2
7.0 x ID'3
2.0 x 10"'
CL
Med
High
a
Low
a
High
Low
Med
a
a
a
Low
Med
Critical effect
Hepatotoxicity
Keratosis/
hyperpigment
a
a
a
Proteinuria
Hepatotox/
nephrotox
Neural tissue
damage
Neurotoxicity
a
a
a
Hyperactivity
RfD
basis/source
Gavage/IRIS
Occupational/
IRIS
IRIS
IRIS
Intratrac.
instill./IRIS
Food/IRIS
Water/IRIS
Water/IRIS
a
a
IRIS
Water/IRIS
Gavage/IRIS
UF
1000
100
3
100
100
10
500
1
10
a
100
100
100
,, . Pathway
..„ Hazard . /
MF .. . hazard
quotient . .
1 2.62 x
1 3.02 x
1 8.87 x
1 1.24 x
1 6.87 x
1 1.49
1 3.21 x
1 1.35
1 1.36 x
1 6.69 x
3 3.03
1 4.71 x
1 1.02
io-3
10"'
io-2
io-3
io-1
10'
IO1
io-2
io-2
2.21 x IO1
3.35 x 10'
I
'These data are either not available or not applicable.
CL = Confidence level
HEAST = Health Effects Assessment Summary Tables
IRIS = Integrated Risk Information System
MF = Modifying factor
RfD = Reference dose
RME = Reasonable maximum exposure
UF = Uncertainty factor
-------
drives the pathway hazard index associated with ingestion of homegrown produce. Additional
noncarcinogenic effects could be incurred from exposure to those contaminants present on-site
for which toxicity data are not available.
The hypothetical on-site resident at the K-1407-C Pond could be exposed to soil and
groundwater contamination. All chemical-specific carcinogenic risks, total pathway risk, and the
total exposure risk estimates are listed in Table 2.11. Although each evaluated pathway yielded
a risk greater than 1 x 10~6, with the exception of dermal contact with groundwater while
showering, the highest risk is due to external exposure to ionizing radiation. The aggregate risk
from exposure to multiple substances across multiple pathways is controlled by the risk incurred
from external exposure to ionizing radiation. It is likely that this risk would be lowered if
radiological decay were taken into account. The excess cancer risk is dominated by exposure to
137Cs and 154Eu. The excess cancer risks from exposure to arsenic and 234U in surface soil
dominate the ingestion pathway risk. The dermal contact pathway risk is driven by arsenic
exposure, while the inhalation pathway risk is dominated by exposure to chromium, 234U, and
238U. Europium-154 and 137Cs control the total pathway risk from external exposure to ionizing
radiation, while "Tc dominates the ingestion pathway risk for homegrown produce. The excess
cancer risk for ingestion of groundwater is due exclusively to arsenic.
Because SFs are not available for all carcinogens of potential concern, the excess cancer
risk for exposure to some contaminants cannot be fully quantified. Although lead is a B2
carcinogen, it is not likely that the additional effects of lead in the soil or groundwater at the
K-1407-B/C Ponds will increase the risk significantly over the relatively high cumulative risk
posed by external exposure to radionuclides. The maximum soil concentrations for lead detected
during the CERCLA soil sampling event was 58 mg/kg and 72 mg/kg for the K-1407-B and
K-1407-C Ponds, respectively; these concentrations are well below the interim soil cleanup level
for lead of 500 to 1000 ppm set forth in the Office of Solid Waste and Emergency Response
Directive 9355.4-02.
Because detection limits for some historic groundwater analyses for lead are above the 15
Hg/L action level established in 56 Federal Register (FR) 26460, comparison of lead
concentrations detected in groundwater at the site cannot be fully evaluated against this criteria.
Only one confirmed analysis for lead at each downgradient monitoring well at the K-1407-B Pond
exceeds the 15 /ig/L action level in unfiltered samples (32 pig/L in UNW-2; 74 /xg/L in UNW-3).
Downgradient monitoring wells UNW-8 and UNW-9 at the K-1407-C Pond have periodically
exceeded the 15 ^g/L action level for unfiltered samples with a maximum concentration of 280
ftg/L in UNW-8. However, lead concentrations in upgradient monitoring wells UNW-6 and
UNW-11 have exceeded the action limit with greater frequency and at greater concentrations than
M302I5.4PS5I 2-48 09/24/93
-------
Table 2.11. Cancer risk estimates Tor on-site residents at the K-1407-C Pond
930215.4PS51
!L
VO
Analyte
Exposure Route:
Arsenic
Beryllium
Americium-241
Cesium- 137
Cobalt-60
Curium-244
Europium- 154
Neptunium-237
Plutonium-238
Plutonium-239
Potassium-40
Technetium-99
Uranium-234
Uranium-235
Uranium-238
RME
(mg/kg)
(pCi/kg)
Ingestion of soil
2.07 x IO1
1.05
4.04 x 10J
2.23 x IO4
4.3 x IO1
-8.00
2.13 x IO3
1.31 x IO4
1.56 x IO3
2.05 x IO4
1.18 x IO4
5.87 x IO5
3.48 x IO5
1.24 x IO4
1.87 x 10s
Intake
(mg/kg-d)
(pCi)
3.25 x IO'5
1.64 x IO-6
5.09 x IO3
2.81 x IO4
5.42 x IO1
0.0
2.69 x IO3
1.65 x IO4
1.96 x IO3
2.58 x IO4
1.48 x IO4
7.39 x 10s
4.38 x IO5
1.56 x IO4
2.35 x 105
SF
(mg/kg.d)-l
1.70
4.30
3.1 x 10-'°
2.8 x 10-"
1.5 x 10-"
2.0 x 10'10
3.0 x lO'12
2.7 x 10'10
2.8 x lO'10
3.1 x lO'"
.1 x 10-"
.3 x 10'12
.4 x 10-'°
.3 x 10-'°
.3 x 10-'°
Weight of
evidence
A
Bt
A
A
A
A
A
A
A
A
A
A
A
A
A
TVpe of cancer
Skin
a
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
SF basis/SF source
a
Intratracheal
Instillation/IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
Chemical-
specific
risk
6 x 10-'
7 x IO6
2 x IO"6
8 x IO-7
8 x lO'10
8 x 10'9
4 x IO'6
6 x IO'7
8 x IO'7
2 x 1C'7
1 x ID'6
6 x 10'5
2 x 10'6
3 x JO'5
Total
pathway
risk
Exposure Route: Dermal contact with soil
Arsenic 2.07 x IO1 7.52 x IO'6
Beryllium 1.05 3.8 x IO'7
1.70
4.30
A
Bl
Skin
Exposure Route: Inhalation of wind-generated dust
Arsenic
Beryllium
Cadmium
Chromium
Nickel
Americium-241
Cesium- 137
Cobalt-60
Curium-244
6.6 x 10'8
3.4 x 10"'
7.4 x 10"'
2.8 x 10'7
1.6 x 10-*
1.3 x 10'5
7.1 x 10'5
1.4 x I0'7
-2.6 x 10'8
2.36 x IO'8
1.21 x 10'9
2.64 x 10"'
1.0 x JO'7
5.71 x IO'7
3.49
1.91 x IO1
3.76 x IO'2
0.0
5.0 x IO1
8.40
6.10
4.1 x IO1
8.4 x 10'1
4.0 x IO'8
1.9 x 10'"
l.6x ID'10
2.7 x IO'8
A
B2
Bl
A
A
A
A
A
A
Respiratory tract
Lung
Many types
Many types
Many types
Many types
Intratracheal
Instillation/IRIS
Various/IRIS
Inhalation/IRIS
a
IRIS
IRIS
IRIS
IRIS
1 x lO'5
2 x IO'6
I x 10'6
I x ID'8
2 x IO'8
4 x IO'6
5 x lO'7
1 x 10'7
4 x 10'10
6 x lO'12
2 x
1 x I0'5
-------
Table 2.11 (continued)
Analyte
Europium- 154
Neptunium-237
Plutonium-238
Plutonium-239
Potassium-40
Technetium-99
Uranium-234
Uranium-235
Uranium-238
Exposure Route:
Americium-24 1
Cesium- 137
Cobalt-60
Curium-244
Europium- 154
Neptunium-237
Plutonium-238
Plutonium-239
Potassium-40
Technetium-99
Uranium-234
Uranium-235
Uranium-238
RME
(mg/kg)
(pCi/kg)
6.8 x IO-6
4.2 x IO'5
5.0 x 10"*
6.6 x IO-5
3.8 x IO'5
1.9 x IO'3
I.I x 10'3
4.0 x 1Q-5
6.0 x lO"4
External exposure to
4.04 x 10}
2.23 x IO4
4.3 x IO1
-8.00
2.13 x IO3
1.31 x IO4
1.56 x IO3
2.05 x IO4
1.18 x IO4
5.87 x IO5
3.48 x IO5
1.24 x IO4
1.87 x IO5
Intake
(mg/kg-d)
(pCi)
.83
.13 x IO1
.34
.77 x IO1
.02 x IO1
5.11 x IO2
2.96 x IO2
1.08 x 10'
1.61 x IO2
soil radiation
1.86 x IO7
1.03 x IO8
1.98 x IO5
0.0
9.82 x IO6
6.04 x IO7
7.18 x IO6
9.43 x IO7
5.42 x IO7
2.7 x IO9
1.6 x IO9
5.7 x IO7
8.59 x IO8
SF
(mg/kg.d)-l
(pCi)-I
1.4 x 10-'°
3.6 x lO'8
4.2 x IO-8
4.1 x 10'8
7.6 x 10'12
8.3 x IO'12
2.7 x I0'8
2.5 x 10-"
2.4 x IO-8
1.6 x I0'12
3.4 x 10-"
1.3 x 10-'°
5.8 x 10'14
6.8 x 10-"
1.8 x lO'12
6.1 x IO14
2.6 x I0'14
7.8 x |0-'2
3.4 x 10""
5.7 x tO'14
9.6 x 10"12
4.6 x 10 l4
Weight of
evidence
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
Type of cancer
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
SF basis/SF source
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
Chemical- Total
specific pathway
risk risk
3 x 10-'°
4 x IO-7
6 x JO'8
7 x ID'7
8 x 10'"
4 x 10'9
8 x 10'6
3 x 1Q-7
4 x JO'6
2 x 10"5
3 x 10'5
3 x lO'3
3 x 10'5
7 x lO'4
1 x IO-4
4 x IO'7
2 x IO-6
4 x I0"4
9 x 10'8
9 x 10'5
5 x IO4
4 x 10"'
Exposure Route: Ingestion of groundwater
Arsenic 9.0 x 10° 1.8 x IO'4
1.70
Exposure Route: Dermal contact with groundwater while showering
Arsenic
9.0 x IO'3
3.51 x 10-
1.70
Skin
Skin
Water/IRIS
Water/IRIS
10"
6 x 10
.-7
5 x 10-'
3 x IO'4
6 x I0'7
-------
Table 2.11 (continued)
9302I5.4PS5I
V
CA
Analyte
Exposure Route:
Arsenic
Beryllium
Americium-241
Cesium- 137
Cobalt-60
Curium-244
Europium- 154
Neptunium-237
Plutonium-238
Plutonium-239
Potassium-40
Technetium-99
Uranium-234
Uranium-235
Uranium-238
RME
(mg/kg)
(pCi/kg)
Intake
(mg/kg-d)
(pCi)
SF
(mg/kg.d)-l
(pCi)-l
Weight of
evidence
Type of cancer
SF basis/SF source
Ingestion of homegrown produce
1.24 x lO'1
2.0 x 10'3
1.00
6.69 x I02
3.0 x 10"'
-1.2 x 10'4
9.00
1.31 x IO2
7.0 x 10'2
1.00
6.47 x I03
8.8 x 105
1.39 x 103
5.0 x 101
7.46 x I02
5.05 x IO'5
8.14 x 10'7
4.2 x 102
2.81 x I05
1.26 x I02
0.0
3.78 x 103
5.5 x 104
2.94 x I01
4.2 x 102
2.72 x I06
3.7 x 10*
5.85 x I05
2.1 x I04
3.13 x 105
1.70
4.30
3.1 x ID'10
2.8 x 10-"
1.5 x lO01
2.0 x IO'10
3.0 x IO'12
2.7 x IO'10
2.8 x IO'10
3.1 x lO'11
.1 x IO01
.3 x IO02
.4 x 10-'°
.3 x 10-'°
.3 x lO'10
A
Bt
A
A
A
A
A
A
A
A
A
A
A
A
A
Skin
a
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
Many types
a
Intratracheal
Instillation/IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
IRIS
Chemical-
specific
risk
9 x 10'5
4 x 10-*
1 x JO'1
8 x 10'6
2 x 10'9
1 x 10'8
1 x 10'5
8 x 10'9
1 x IO-8
3 x JO"5
5 x ID'4
8 x 10'$
3 x JO"6
4 x 10's
Total exposure risk
Total
pathway
risk
7x IO"4
7 x IO'3
These data are either not available or not applicable.
HEAST = Health Effect Assessment Summary Tables
IRIS = Integrated Risk Information System
RME = Reasonable maximum exposure
SF = Slope factor
1
A = sufficient evidence of carcinogenicity in humans; human carcinogen
Bl = limited evidence of carcinogenicity in humans
D2 = sufficient evidence of carcinogenicity in animals with inadequate or lack of evidence in humans
D = not classifiable as to human carcinogenicity (lack of or no evidence)
-------
downgradient wells (maximum concentration of 334 ^ig/L in UNW-6). This indicates that lead
in downgradient wells is not attributable to migration from the pond soils.
Results of the evaluation of exposure to noncarcinogenic contaminants for the on-site
resident at the K-1407-C Pond are given in Table 2.12. Noncarcinogenic effects could occur
from exposure to the soil and the groundwater by ingestion, dermal contact, inhalation, and
consumption of homegrown produce. Exposure to chromium drives the pathway hazard index
associated with the inhalation of wind-generated dust while exposure to mercury contributes
substantially to the elevated pathway hazard index values for the ingestion of homegrown
produce. Additional non-carcinogenic effects could be incurred from exposure to those
contaminants at the site that do not have RfDs; however, these effects cannot be quantified.
Tables 2.13 and 2.14 show general and site-specific uncertainty factors that may influence
the human health risk assessment results for the K-1407-B/C Ponds.
Environmental Risks
There are no critical habitats or threatened or endangered species affected by site
contaminants. The K-1407-B/C Ponds do not provide a habitat to support significant aquatic
communities, do not currently discharge to surface waters, and are not expected to discharge to
surface waters via direct surface flow in the future. Therefore, aquatic ecological effects were
not assessed. Because the ponds encompass a small area within an industrial complex and do not
incorporate highly valued habitat features, effects on natural terrestrial communities were not
assessed. However, because it may be desirable to revegetate these ponds, an assessment was
performed on the ability of the pond soils to support a plant community sufficiently vigorous to
cover and stabilize the soil. The results indicate that the pond soils could be toxic to plants due
to high concentrations of Hg, Ni, Zn, and other metals. However, these results are highly
uncertain due to differences in soil composition, metal form, and plant sensitivity. Additional
evaluation of environmental and ecological risks may be provided as part of a subsequent sitewide
ecological risk assessment at K-25.
Summary
According to EPA, an excess cancer risk greater than 1 x 10"6 (1 in a million) is cause
for concern and requires close scrutiny, and an excess cancer risk greater than 1 x 10"* (1 in
10,000) is considered unacceptable by the EPA (EPA 1989a). The excess risk to the general
plant worker are well below the EPA lower threshold of concern. On-site workers are exposed
through inhalation of airborne dust, dermal contact and ingestion of contaminated soil, and
external exposure to ionizing radiation. The on-site worker is estimated to be exposed to an
excess cancer risk of 4 x 10"6, or four chances in a million more likely to contract cancer in a
D930215.4PS51 2-52 09^4/93
-------
3
s
3
«ji
Analyte
Table 2.12.
RME
(mg/kg)
Intake
(mg/kg-d)
Exposure Route: Ingestion of soil
Arsenic
Barium
Beryllium
Boron
Cadmium
Chromium
Manganese
to
i
Oi
w Mercury
Molybdenum
Nickel
Silver
Vanadium
Zinc
2.07
1.17
1.05
1.37
2.31
x 10'
x I02
x I01
8.6 x 10'
1.56
1.04
3.74
5.07
x 103
x 10'
x 102
9.0 x 10-'
5.02
8.79
x 10"
x 10'
2.94 x
1.65 x
1.49 x
1.95 x
3.28 x
1.22 x
2.22 x
1.47 x
5.31 x
7.21 x
1.28 x
7.13 x
1.25 x
io-4
io-3
io-5
io-4
io-5
io-3
io-2
io-4
io-5
IO3
io-5
lO'4
io-3
Hazard index estimates
RfD
(mg/kg-d)
1.0 x I0'3
7.0 x 10'2
5.0 x IO'3
9.0 x IO'2
l.Ox 10'3
5.0 x JO'3
1.0 x 10'1
3.0 x 10'4
4.0 x IO'3
2.0 x 10'2
3.0 x 10'3
7.0 x 10'3
2.0 x IO'1
CL
High
a
Low
a
High
Low
Med
a
a
a
Med
Low
Med
for on-site residents at the K-1407-C Pond
Critical effect
Keratosis/
hyperpigment
a
a
a
Proteinuria
Hepatotox/
nephrotox '
Neural tissue
damage
Neurotoxicity
a
a
Argyria
a
Hyperactivity
RfD
basis/source
Occupational/
IRIS
IRIS
IRIS
Intratrac.
instill./IRIS
Food/IRIS
Water/IRIS
Water/IRIS
a
a
IRIS
Oral/IRIS
Water/IRIS
Gavage/IRIS
UF
100
3
100
100
10
500
1
10
a
100
2
100
100
Mp Hazard PKathw7
MF . . hazard
quotient . .
index
1 2.94 x
2.36 x
2.97 x
2.17 x
3.28 x
2.44 x
1 2.22 x
io-1
io-2
io-3
io-3
io-2
10-'
io-1
4.9 x lO'1
1.33 x
lO'2
3 3.6 x IO'1
4.26 x
1.02 x
6.24 x
io-3
io-1
io-3
Exposure Route: Dermal contact with soil
Arsenic 2.07 x IO1 4.21 x 10"4
l.Ox IO'3 High
Keratosis/ Occupational/ 100
hyperpigment IRIS
Barium
Beryllium
Boron
Cadmium
1.17 x IO2
1.05
1.37 x IO1
2.31
2.37 x 10'3
2.13 x 10"5
2.79 x IO'4
7.0 x 10'2
5.0 x IO'3
9.0 x IO'2
4.68 x 10'5 1.0 x 10°
Low
a
High
Proteinuria
IRIS
IRIS
Intratrac.
instill./IRIS
Food/IRIS
3
100
100
10
1 4.21 x 10"'
1 3.38 x 10'2
I 4.25 x I0'3
1 3.1 x IO'3
I 4.68 x 10'2
1.80
-------
S
s
s
U»
Analyte
Chromium
Manganese
Mercury
Molybdenum
Nickel
Silver
Vanadium
Zinc
RME
(mg/kg)
8.6 x 10'
1.56 x IO3
1.04 x 10'
3.74
5.07 x I02
9.0 x 10-'
5.02 x I01
8.79 x 10'
K> Exposure Route: Inhalation
|£ Barium
Chromium
Manganese
Mercury
3.7 x IO'7
2.8 x I0'7
5.0 x IO-6
3.3 x 10'8
Exposure Route: Ingestion
Arsenic
Cadmium
Manganese
Mercury
9.0 x IO'3
1.7 x !0'2
3.3 x 101
5.1 x 10°
Intake
(mg/kg-d)
1.75
3.17
2.1 x
7.59
1.03
1.83
1.02
1.79
x 10°
x 10'2
10"
x 10'5
x 10'2
x ID'5
x IO'3
x 10'3
of wind-generated
1.24
9.35
1.67
x 10'6
x lO'7
x 10'5
1.1 x 10 7
RfD
(mg/kg-d)
5.0 x
1.0 x
3.0 x
4.0 x
2.0 x
3.0 x
7.0 x
2.0 x
dust
1.43
5.7 x
1.14
8.57
io-3
lo-1
10-"
io-J
io-2
io-3
io-3
io-1
x 10 4
io-7
x 10'4
x 10'5
Tfeble 2.
CL
Low
Med
a
a
a
Med
Low
Med
a
a
a
a
12 (continued)
Critical effect
Hepatotox/
nepnrolox
Neural tissue
damage
Neurotoxicity
a
a
Argyria
a
Hyperactivity
Fetotoxicity
Respiratory
effects
Respiratory/
psychomotor
Neurotoxicity
RfD
basis/source
Water/IRIS
Water/IRlS
a
a
IRIS
Oral/IRIS
Water/IRIS
Oavage/IRIS
IRIS
IRIS
Inhalation/
IRIS
Inhalation/
HEAST
UF
500
1
10
a
100
2
100
100
1000
a
900
30
. . . Pathway
MF Hazafd hazard
('UOtient index
1 3.49 x
1 3.17 x
1 7.01 x
1 1.9 x
3 5.15 x
1 6.09 x
1 1.46 x
1 8.93 x
— > 8.6 x
— " 1.6
— * 1.5 x
— a 1.3 x
io-1
io-1
io-1
io-2
io-1
io-3
io-1
io-3
2.57
10°
10 '
10°
1.8
of groundwater
1.4 x 10°
2.64
5.12
7.91
x lO'3
1.0 x
5.0 x
10 3
io-4
1.0 x ID'1
x 10'4
3.0 x
10 4
High
High
Med
a
Keratosis/
hyperpigment
Proteinuria
Neural tissue
damage
Neurotoxicity
Occupational/
IRIS
Food/IRIS
Water/IRIS
IRIS
100
10
1
10
1 1.40
1 5.27
1 5.12 x IO1
1 2.64
-------
Table 2.12 (continued)
3
IM
Analyte
Molybdenum
RME
(mg/kg)
1.3 x IO'2
Intake
(mg/kg-d)
2.02 x 10°
RfD
(mg/kg-d)
4.0 x 10°
CL
a
Critical effect
a
RfD
basis/source
IRIS
UF
a
MF
1
.. . Pathway
Hazard , ,
.. . hazard
quotient . .
index
5.04 x
JO'1
6.1 x 10'
Exposure Route: Dermal contact with groundwater
K>
i
ISl
3
g
Arsenic
Cadmium
Manganese
Mercury
Molybdenum
9.0 x 10°
1.7 x 1C'2
3.3 x IO1
5.1 x IO"3
1.3 x lO'2
Exposure Route: Ingestion
Arsenic
Barium
Beryllium
Boron
Cadmium
Chromium
Manganese
Mercury
Molybdenum
Nickel
Silver
Vanadium
1.24 x 10-'
1.75
2.0 x IO'3
2.75 x IO1
3.46 x 10"'
3.87 x 10-'
7.82 x IO1
2.07
2.24 x IO'1
3.04 x IO1
9.0 x IO'2
1.51 x 10''
1.98 x I0'6
3.74 x I0"6
7.26 x 10'3
1.12 x 10'6
2.86 x 10'6
of homegrown
3.86 x lO'4
5.44 x 10°
6.22 x 10-*
8.55 x 10'2
1.08 x 10'3
1.2 x 10'3
2.43 x 10'1
6.44 x lO'3
6.97 x IO"4
9.47 x 10"2
2.8 x IO-4
4.7 x IQ-"
1.0 x W3
5.0 x 10'4
1.0 x IO'1
3.0 x IQ-"
4.0 x I0'3
produce
1.0 x IO'3
7.0 x 10'2
5.0 x 10'3
9.0 x 10'2
I.Ox 10°
5.0 x I0'3
1.0 x IO'1
3.0 x IQ-4
4.0 x 10°
2.0 x IO'2
3.0 x I0'3
7.0 x 10°
High
High
Med
a
a
High
a
Low
a
High
Low
Med
a
a
a
Med
Low
Keratosis/
hyperpigment
Proteinuria
Neural tissue
damage
Neurotoxicity
a
Keratosis/
hyperpigment
a
a
a
Proteinuria
Hepatotox/
nephrotox
Neural tissue
damage
Neurotoxicity
a
a
Argyria
a
Occupational/
IRIS
Food/IRIS
Water/IRIS
IRIS
IRIS
Occupational/
IRIS
IRIS
IRIS
Intratrac.
instill./IR!S
Food/IRIS
Water/IRIS
Water/IRIS
a
a
IRIS
Oral/IRIS
Water/IRIS
100
10
1
to
a
100
3
100
100
10
500
1
10
a
100
2
100
1
1
1
1
1
1
1
1
1
1
1
1
1
1
3
1
1
1.98 x
7.48 x
7.26 x
3.74 x
7.15 x
3.86 x
7.77 x
1.24 x
io-3
io-3
io-2
io-3
io-4
8.65 x JO'2
10-'
io-2
IO3
9.5 x lO'1
1.08
2.41 x
2.43
2.15 x
1.74 x
4.73
9.33 x
6.71 x
io-1
10'
10"'
io-2
io-2
-------
D9302I54PSS!
Analyte
Zinc
Total pathway
RME
(mg/kg)
7.92 x 101
hazard index
Intake
(mg/kg-d)
2.46 x 10'1
RfD
(mg/kg-d)
2.0 x 10'1
Table 2.12 (continued)
CL Critical effect . .R/° UF MF Hazard
basis/source quotient
Med Hyperactivity Gavage/lRIS 100 1 1.23
Pathway
hazard
index
3.29 x 10'
1.0 x 102
"These data are either not available or not applicable.
CL = Confidence level
HEAST = Health Effects Assessment Summary Tables
IRIS = Integrated Risk Information System
MF = Modifying factor
RID = Reference dose
RME = Reasonable maximum exposure
UF = Uncertainty factor
-------
Table 2.13. General uncertainty factors
s
8
Uncertainty factor
Effect of uncertainty
Comment
N>
Use of cancer slope factors
May overestimate risks
Risks/doses within an exposure route May over- or underestimate risks
assumed to be additive
Toxicity values derived primarily from May over- or underestimate risks
animal studies
Toxicity values derived primarily from May over- or underestimate risks
high doses; most exposures are at low
doses
Toxicity values
Effect of absorption
May over- or underestimate risks
May over- or underestimate risks
Effect of applying critical toxicity values May overestimate risks
to soil exposures
Exposures assumed constant over time May over* or underestimate risks
Slopes are upper 95th percent confidence limits derived from the
linearized model. Considered unlikely to underestimate true risk
Does not account for synergism or antagonism
Extrapolation from animals to humans may induce error due to
differences in pharmacokinetics, target organs, and population
variability
Assumes linearity at low doses. Tends to have conservative
exposure assumptions
Not all values represent the same degree of certainty. All are
subject to change as new evidence becomes available
The assumption that absorption is equivalent across species is
implicit in the derivation of the critical toxicity values.
Absorption may actually vary with species and age
Assumes bioavailability of contaminants sorbed onto soils is the
same as detected in laboratory studies. Contaminants detected in
studies may be more bioavailable
Does not account for environmental fate, transport, or transfer that
may alter concentration
-------
Table 2.14. Site-specific uncertainty factors
Uncertainty Factor
Effect of Uncertainty
Comment
00
Metals analysis for total metals only
May overestimate risks
Not all chemicals at the site have toxicity May underestimate risks
values
Exposure assumptions
May over- or underestimate risks
It is difficult to determine the sources and May over- or underestimate risks
their relative contributions to groundwater
contamination downgradient of the ponds
Radioisotopes are not included as analytes May underestimate risks
in groundwater
The source of organics in K-1407-B soil May overestimate risks
is indeterminable
Soil background samples are not available May overestimate risks
No air monitoring data are available
May over- or underestimate risks
Transport equations used to estimate the May overestimate risks
air concentration lacked constraints on the
availability of soil particles for transport
Exposures assumed constant over time
May over- or underestimate risks
Did not distinguish between valences or speciation.
Assumed the metal was present in its most toxic form
These chemicals are not addressed quantitatively
Assumptions regarding media intake, population
characteristics, and exposure patterns may not
characterize exposures
Statistical t-test used in selecting potential
contaminants of concern for groundwater
Soil in both ponds contain radionuclides;
comprehensive assessment of groundwater is not
possible
It is likely that organics are not related to K-1407-B,
but to groundwater
It is impossible to eliminate metals which are not site-
related based on a screening evaluation
Models were used to develop air concentrations
Soil moisture and the cohesive nature of the clay soil
in the ponds act to reduce the erosion rate and the
subsequent concentrations in air
Does not account for environmental fate, transport, or
transfer that may alter concentration
-------
lifetime than if no contamination existed at the K-1407-B/C Ponds. The hypothetical future on-
site resident would be exposed through ingestion and contact with contaminated soil, external
exposure to ionizing radiation, inhalation of airborne dust, ingestion of contaminated
groundwater, dermal contact with water, inhalation of organic volatiles during bathing, and
consumption of contaminated homegrown vegetables. The aggregate excess risk from exposure
to multiple contaminants across all pathways for the hypothetical resident is estimated at
1 x 10"2, or 1 extra chance in 100 to contract cancer solely because of site contamination.
The remedial action will provide protection to the on-site worker, the general plant
employee, and wildlife by eliminating pathways of exposure by backfilling at the site. This
remedial action will also provide protection to the potential intruder or future on-site resident by
eliminating pathways of exposure and through the use of institutional controls. Institutional
controls eliminate the potential risk to the hypothetical homesteader for as long as the controls
remain in place by preventing access to the ponds area. The risk level following implementation
of this action will be reduced below the threshold of concern (10~6, or 1 in a million) established
by EPA. Systematic toxicity will also be reduced.
The results of the risk assessment for the K-1407-B Pond and K-1407-C Pond are
summarized in Fig. 2.5. The risk assessments for the K-1407-B Pond and the K-1407-C Pond
indicate that present and future on-site exposure is likely to be a concern. Estimated risks
incurred by an individual living near or on K-1407-B Pond or K-1407-C Pond at baseline
conditions would be unacceptable.
Actual or threatened releases of hazardous substances from this site, if not addressed by
implementing the response action selected in this ROD, may present an imminent and substantial
endangerment to public health, welfare, or the environment.
D93021J.4PS51 2-59 09/24/93
-------
D930213.4PS51
K)
&
1
a
1 -
10 -1-
10 "2-
-3
10
if 10 "*-
8 -5
1 1V
^ 10
8-7
* 10 ~
"5 *
10 ^
-9
10 ^
-10
10 -
-11
10
Unacceptable Range ^B ^^
EPA Range of Concern
© ©
(
» (\
Acceptable Range
f ?
Bpond Cpond Bpond Cpond Bpond Cpond
On-Stte Worker General Plai
Exposure Scenario
it
Blair Road
RADIAN
Source: Energy
Date: 1991
Systems
Environmental Restoration Program
Bpond Cpond
Resident
A comparison by scenario of total
excess cancer risk from exposure
to contaminants at the
K-1407-B/C Ponds.
Fig. 2.6
-------
DESCRIPTION OF ALTERNATIVES
As part of the FS conducted for the K-1407-B/C Ponds, remedial alternatives were
developed to address residual metals, radiological, and VOC contamination in the pond soils.
Remedial alternatives developed under CERCLA must protect human health and the environment
from the hazards at K-1407-B/C Ponds and comply with the associated administrative
requirements. Each alternative was evaluated with respect to CERCLA screening criteria.
Groundwater contamination at the site will be addressed as part of the K-25 Groundwater OU
Rl/FS and is not addressed by these remedial alternatives. Under the focused FS process, six
alternatives were evaluated for remediation of soil contamination at the K-1407-B/C Ponds site:
• Alternative 1: No action—Under Alternative 1, no further action would be taken at
the site.
• Alternative 2: Engineered Rock Fill—This alternative consists of filling the K-1407-B
Pond with rock fill, placing a cover layer of a few feet of compacted soil above the
rock, and filling the K-1407-C Pond with soil.
• Alternative 3: Engineered Soil Fill—This alternative entails backfilling both the ponds
with borrow soil in accordance with precise technical specifications.
• Alternative 4: Backfill and Clay Cap—Backfilling and placement of a clay cap
according to engineering specifications provides a hydraulic barrier and helps minimize
infiltration and percolation of surface waters.
• Alternative 5: Five-Component RCRA Cap—The composite five-component RCRA
cap is a sophisticated cap consisting of multiple layers, including a synthetic membrane
that eliminates virtually all infiltration.
• Alternative 6: Excavation and Treatment—Excavation entails the removal of
contaminated soils and subsequent treatment by fixation for storage of waste.
Alternative 1 is included as a comparison baseline in accordance with the NCP.
Alternatives 2, 3, 4, 5, and 6 each intend to fulfill the requirements of Sect. 121(d)(l) of SARA.
As part of the RI/FS, soil cleanup levels for the protection of human health were
generated as preliminary remediation goals (PRGs) based on EPA-recommended equations. The
EPA-recommended equation for calculating PRGs for radionuclides in soil combines the two
pathways of external irradiation and soil ingestion because a residential receptor could be exposed
by both pathways simultaneously. The produce ingestion pathway was not considered in
calculating PRGs for radionuclides because the risks associated with this pathway are negligible
in comparison with those for external irradiation and soil ingestion. Remediation resulting in soil
D93021S.4PSS1 2-61 09/24/93
-------
concentrations that adequately reduce risks associated with soil ingestion and external irradiation
would likewise eliminate unacceptable risks (i.e., >1 x 10"6) associated with produce ingestion.
The equation for calculating PRGs was derived by EPA from the equation used to
calculate risk. The EPA-recommended default value for the shielding factor was used to allow
consideration of the shielding effect of buildings, such as the walls of the on-site resident's house.
The age-adjusted soil ingestion factor combines the different ingestion rates and body weights of
the child and adult receptors. In accordance with EPA guidance, each SF used in calculating a
PRO for a radionuclide incorporated the SFs for all decay products since secular equilibrium is
assumed. The values used for the other variables in the equation were the same ones used in the
risk calculations.
Since EPA has not provided equations for calculating PRGs for the produce ingestion and
dust inhalation exposure pathways, PRGs were back-calculated using the same equations used to
calculate risk. Likewise, the values used in the risk calculations for ingestion rate, inhalation
rate, exposure frequency, exposure duration, body weight, and averaging time were used in
deriving PRGs. However, because the majority (approximately 80%) of the risk from ingestion
of metals in produce is due to the 6 years of childhood exposure, a body weight of 15 kg and
exposure duration of 6 years were used to calculate these PRGs. The calculated risk-based PRGs
are shown in Table 2.15. The PRG shown for chromium is a target air concentration rather than
a target soil concentration.
Remediation that achieves these PRGs for protection of human health is likely to also
eliminate the potential for adverse effects on plant life. The PRGs listed in Table 2.15 are lower
than the minimum phytotoxic concentrations (i.e., those toxic to plants) for the same metals, with
the exception of zinc. The phytotoxicity value for zinc is based on one study of one plant
species, suggesting considerable uncertainty in that value being applied to all plants in all soil
types.
A great deal of conservatism has been incorporated into the PRGs. In addition to the very
conservative exposure assumptions adapted from EPA risk assessment guidance documents, SFs
and RfDs established by EPA directly influence the outcome of PRG calculations. It is important
to keep in mind that the PRGs are the target concentrations to which the hypothetical on-site
resident would be exposed for baseline, or current, site conditions. Therefore, excavation of soil
containing contaminant levels above the PRGs is not necessarily required if uncontaminated soil
or other shielding material is placed over the contaminated soil such that residential exposure to
the soil exceeding PRGs is eliminated.
Treatment options for the disposal of residual radiological contamination in soil were
evaluated in the FS for the K-1407-B/C Ponds. Treatment/disposal of radioactive waste is based
D930215.4PS51 2-62 09/24/93
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Table 2.15.
Contaminant
Europium- 154
Cesium- 137
Thorium-230
Americium-241
Cobalt-60
Neptunium-237
Potassium-40
Uranium-234
Uranium-235
Uranium-238
Technetium-99
Mercury
Manganese
Nickel
Zinc
Cadmium
Chromium
Preliminary remediation goals for the K-1407-B/C Pond soils
Exposure route
External radiation/soil ingestion
External radiation/soil ingestion
External radiation/soil ingestion
External radiation/soil ingestion
External radiation/soil ingestion
External radiation/soil ingestion
External radiation/soil ingestion
External radiation/soil ingestion
External radiation/soil ingestion
External radiation/soil ingestion
Produce ingestion
Produce ingestion
Produce ingestion
Produce ingestion
Produce ingestion
Produce ingestion
Inhalation of dust
Target soil concentration/activity
4 x 10'3 pCi/g
4 x ID'3 pCi/g
3 x 10'3 pCi/g
2 x 10'3pCi/g
2 x ID'3 pCi/g
2 x lO'3 pCi/g
3.3 x 10'2 pCi/g
3 x 10'3pCi/g
7 x 10'3pCi/g
1 x 10'3pCi/g
1.8pCi/g
0.1 mg/kg
156 mg/kg
130 mg/kg
52 mg/kg
1 mg/kg
2 x lO-'mg/m3
(air concentration)
on three technical principles that are not always simultaneously applicable or administratively
feasible.
• A sufficient delay will allow the complete decay of short-lived isotopes, first, and of
all radioactivity in the long term ("delay and decay").
• Dilution of concentrated waste will reduce the specific bulk radioactivity of the
material to acceptable levels.
• Containment and confinement of the waste will limit the risk posed by the radioactive
material.
Since a cement batch plant was operated on-site during a previous fixation project,
treatment by stabilization and solidification with cement appears to be a viable treatment choice.
The nature and threat of radiologically contaminated soils at the bottom of the ponds is
comparable, even if less intense, to waste previously treated by portland cement fixation.
Hypothetically, after excavation the contaminated soils may be stockpiled, mixed with cement,
and formed in solid blocks for storage. However, this and all other currently available methods
to accomplish remediation of a site contaminated with radionuclides when the "delay and decay"
method is impractical will result in the production of further waste materials, the nature of which
is possibly different than the original waste.
D9302IS.4PSSI
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Although the treatment option would reduce residual risks at the K-1407-B/C Ponds site,
it would increase the risk associated with treating, handling, and storage of the waste.
Furthermore, this option would create the need for long-term management of containerized waste.
While such treatment would be consistent with CERCLA preference for treatment as a principal
element to remediate threats at the site, it would be inconsistent with CERCLA preference for
permanent solutions (the waste would still exist, would be stored above ground, and would still
require management) and preference for in situ treatment of waste and minimization of waste by-
products resulting from remedial action. In a practical sense, the real overall advantage that
solidification could offer with regard to risk reduction is questionable.
Because current technology does not offer a means to effectively treat residual radiological
contamination such as that found at the K-1407-B/C Ponds site, the treatment of principal threats
is deemed to be impracticable. Therefore, management of in situ residues is a more appropriate
remedy at this site.
Engineering controls proposed under the fill/cap Alternatives 2, 3, 4, and 5, would
effectively deactivate all direct exposure and soil pathways of exposure identified in the baseline
risk assessment, to all receptors. All existing exposure pathways and accordingly all risk
associated with each pathway would be eliminated. The effectiveness of the fill/cap remedies is
evidenced by RESRAD computer modeling conducted as part of the RJ/FS for the K-1407-B/C
Ponds. The RESRAD computer code was developed as a compliance tool to develop residual
contamination guidelines at DOE facilities. RESRAD modeling conducted for the K-1407-B/C
Ponds and included in the RI/FS report show that the effectiveness of the engineered fill option
would be sufficient to maintain exposure levels within DOE guidelines for at least 10,000 years
(the maximum span for which the model was run), even without maintenance (DOE 1992a). For
the foreseeable future, the integrity of the fill/cap options would be enhanced by regular
surveillance and maintenance as part of ongoing operations at the K-25 Site.
Although engineering controls proposed under Alternatives 2, 3, 4, and 5 would
effectively deactivate all direct exposure and soil pathways of exposure identified in the baseline
risk assessment, the continued presence of residual soil contamination on-site represents a
potential threat for the hypothetical future on-site resident. Therefore, institutional controls are
considered a component of all of these alternatives.
The purpose of institutional controls at the K-1407-B/C Ponds is to prevent the inadvertent
exhumation of the residual soil contamination buried under the soil cover. Further discussion of
the protection provided by Alternatives 2 through 5 to the hypothetical future on-site resident in
the absence of institutional controls is given in the Summary of Comparative Analysis of
Alternatives section of this ROD. It is worth mentioning that, while excavation and treatment of
D93OZ15.4PS51 2-64 09/24/93
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residual soil contamination at the K-1407-B/C Ponds would eliminate the need for institutional
controls on a site-specific basis, the stored waste would create a hazard for which the
implementation and maintenance of institutional controls would still be necessary.
The implementation of institutional controls requires the use of physical barriers or legal
restrictions or both. The K-1407-B/C Ponds are inside the perimeter fence of the K-25 Site, a
DOE facility with controlled access. As long as K-2S is under the jurisdiction of the U.S.
government, residential use of the property can easily be avoided through controlled access. If
the property is released in the future and the preclusion of residential use is deemed necessary,
this preclusion may depend more on legal restrictions than on physical means of access control.
For instance, if the ORR were to become a wildlife refuge, the problem of avoiding residential
use may solve itself. Otherwise, covenants and deed restrictions can be implemented as
customary with the transfer of any commercial property. It is reasonable to express a realistic
and effective commitment to the premise that physical institutional controls will be maintained
as long as the property is owned by the U.S. government and that legal provisions for the
prevention of residential land use will be part of any property release agreement, in accordance
with Sect. 120(h) of CERCLA, as amended.
Institutional controls, reopeners, and contingencies to ensure that the remedy remains
effective, to be agreed upon with the state, will be implemented. For example, under DOE Order
5400.5 the selected remedy is considered restricted closure. Therefore, if at any point in the
future unconditional release of the site becomes a possibility, DOE (or its successor) shall conduct
a review of the remedy and current site conditions prior to transfer of the K-25 Site from DOE
(or its successor) to another person or entity. Any property transfer will follow the procedure
outlined in the Federal Facility Agreement for the Oak Ridge Reservation (hereafter referred to
as the FFA) (DOE 1992d), Sect. XLffl, Property Transfer. Additionally, because this remedy
will result in hazardous substances remaining on-site above health-based levels, a review will be
conducted every 5 years, beginning within 5 years after commencement of the remedial action,
to ensure that the remedy continues to provide adequate protection of human health and the
environment, in accordance with CERCLA 121(c).
Each alternative in this section is evaluated for compliance with applicable or relevant and
appropriate requirements (ARARs) and to be considered (TBC) guidance for the remediation of
the K-1407-B/C surface impoundments. Those ARARs considered applicable for the remediation
of the ponds are those pertaining to floodplain protection [10 CFR 1022 and 40 CFR 6
(Appendix A)], RCRA clean closure (40 CFR 265), on-site construction/excavation [Tennessee
Code Annotated (TCA) Sect. 1200-3-8], fugitive dust control (TCA Sect. 1200-3-8.01), and
surface water control (40 CFR 122, TCA Sect. 1200-4-3). DOE orders regulating exposure and
long-term management and disposal of residual waste, while not regarded as ARARs, are treated
D93Q2I5.4PS5I 2-65 09/M/93
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as TBC guidance and/or criteria. The wetlands survey conducted for the site indicated that there
are no wetlands areas present in the K-1407-B or -C Ponds. Pending concurrence with this
finding from the U.S. Army Corps of Engineers (USAGE), regulations pertaining to wetlands
[10 CFR 1022 and 40 CFR 6 (Appendix A)] are not ARARs for this site. A detailed evaluation
of ARAR compliance is presented for each alternative description in this section, and a
comparison of alternative ARAR compliance is presented in the Summary of Comparative
Analysis of Alternatives section of this ROD.
Alternatives 2 through 5 each would meet the exposure limits of DOE Order 5400.5.
This order generically sets guideline exposure limits for all radionuclides except 226Ra, 228Ra,
230Th, and 232Th, for which activity guidelines are set. The exposure limits are satisfied by the
elimination of exposure pathways. Although the specific activity limits for 230Th are exceeded
in some areas of the K-1407-B Pond, there will be no risk from this contaminant after taking
necessary control measures at the site. However, the K-1407-B/C Ponds will be revisited by
DOE or its successor with regard to residual radiological contamination if unconditional release
of the property becomes a possibility in the future, and any property transfer will follow the
procedure outlined in the FFA (DOE 1992d), Sect. XLIII, Property Transfer.
Common Assumptions for Alternatives 2 through 5
Components of the conceptual design common to Alternatives 2 through 5 are summarized
below. This list includes assumptions and activities for these remedial alternatives.
• The K-1407-B Pond would be dewatered before and during backfill operations, except
for Alternative 2.
• Silt fences and other erosion control devices will be employed as necessary.
• Surface water diversion is included as a percentage of the total cost; design of
necessary control works will take place at a later stage.
• No roads other than temporary access roads will be built.
• Minimal dust suppression measures will be implemented as required for the haul
roads.
• If removed, it is likely water from the K-1407-B Pond will be processed through the
CNF.
• Health and Safety personnel will monitor the site and workers.
• All alternatives include surface contouring and revegetation as applicable.
D9302154PS5I 2-66 09/24/93
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• Construction equipment used during operations will be decontaminated on-site if
required.
• Work will be done in Level D protective equipment.
• All borrow soils and clays will be taken either from the West Borrow Area,
approximately 11 km from the site (21 km round trip), or from a site with similar soil
properties. Rock borrow is also available in the vicinity of the K-1407-B/C Ponds
site.
• The in-place density of the soils in the borrow area is assumed to be 125 lb/ft3.
Specific design criteria for the K-1407-B/C Ponds will be developed during the remedial
design phase. The following description of alternatives uses the design assumptions established
in the RI/FS (DOE 1992a). All estimates for soil and rock fill and soil excavation are based on
generalized assumptions; actual volumes could vary significantly during the design/construction
phase of remediation.
For the purpose of cost comparisons, present worth was calculated for a 30-year period
for each alternative. However, the use of this 30-year period does not infer that the site will
necessarily be suitable for release from institutional controls at the end of that period. It is
recognized that institutional controls, consisting of the use of physical barriers, legal restrictions,
or both, will remain as long as unacceptable risks exist at the site. Institutional controls may be
required at the site for a period substantially longer than 30 years.
Alternative 1—No Action
CERCLA requires that the no-action alternative be evaluated to serve as a baseline for
comparison. This alternative would not mitigate current or future potential risk of the site
through soil or surface water pathways and does not comply with DOE Order 5400.5 regarding
exposure limits or DOE Orders 5400.5, Chapters II and IV, and 5820.2A regarding long-term
management of residual radioactive contamination left in place.
Alternative 2—Engineered Rock Fill
This alternative consists of filling the K-1407-B Pond with coarse, granular material
(crushed rock) and filling the K-1407-C Pond with engineered compacted soil. It is estimated
that 63,000 yd3 of soils and 14,000 yd3 of crushed rock would be placed in the ponds for the
implementation of Alternative 2.
For the K-1407-B Pond, rock fill is a suitable backfill material that can be placed in its
waterlogged environment without difficulty. It is expected that displaced water will flow away
D9302I5.4PSJ1 2-67 W/24/93
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naturally as groundwater, establishing a dry surface above the water table. Soil will then be
applied over the rock fill; it will be graded; and vegetation will be planted.
The K-1407-C Pdnd, unlike the K-1407-B Pond, is not waterlogged. Because compacted
soil is more cost-effective than crushed rock fill, the K-1407-C Pond would be filled with
compacted borrow soil; its surface would also be graded and planted with vegetation. The
borrow soil will be spread in thin lifts and compacted to specification with rollers or vibratory
compactors. Placement of fill is monitored against prescribed technical specifications.
Engineered-compacted fill must meet precisely defined in situ quality tests before its approval for
use. Because of compaction and quality control, this fill is not subject to significant settlement;
therefore, it requires little or no maintenance. Alternative 2 would not generate man-made
by-product wastes that require management.
Flooding in the area would not compromise the remedial action taken at the ponds;
therefore, 10 CFR 1022 and 40 CFR 6 (Appendix A) would be met. Final remediation under
Alternative 2 would meet RCRA clean closure requirements (40 CFR 265). During construction,
stormwater runoff controls (40 CFR 122, TCA Sect. 1200-4-3) and fugitive dust controls
(TCA Sect. 1200-03-8.01) would be implemented. Alternative 2 would meet the exposure limits
of DOE Order 5400.5 and comply with the requirements of 5400.5, Chapters II and IV, and
5820.2A regarding the long-term management of residual radioactive contamination left in place.
No wetlands areas were identified in the ponds by the wetlands survey conducted for the site, and
concurrence with this finding is expected from the USAGE. If wetlands were determined to be
present at the site, they would be destroyed by this alternative; however, mitigative measures
would be taken to enhance other wetlands areas so no net loss of wetlands would occur, thus
meeting 10 CFR 1022 and 40 CFR 6 (Appendix A).
Capital cost: $4.5 million
Annual Operations and Maintenance (O&M) cost: $33,000
Present worth cost over 30 years: $5.0 million
Months to implement: 15
Alternative 3—Engineered Fill
The K-1407-B Pond would be dewatered, and the ponded water would be pumped to and
processed at the CNF. This alternative would entail placing an estimated 75,000 yd3 of
compacted fill, grading materials, and soils over existing empty impoundments for filling,
contouring, drainage control, and revegetation. This alternative would require water treatment
at CNF but would not generate other by-product wastes that require management. Compliance
with ARARs and TBCs would be the same for Alternatives 3 as for Alternative 2.
D93021J.4PSS1 2-68 09/24/93
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Capital cost: $5.5 million
Annual O&M cost: $33,000
Present worth cost over 30 years: $6.0 million
Months to implement: 15
Alternative 4—Backfill and Clay Cap
The K-1407-B Pond would be dewatered, and soil fill would be emplaced to the
appropriate engineering specifications in both ponds before placement of a clay cap. A clay cap
would act as a hydraulic barrier, adding a measure of protection from infiltration of rain and
surface waters to the backfilled pond. This cap is an engineered-compacted fill layer that must
meet both structural and hydraulic performance criteria for acceptance. While compacted backfill
must meet specifications aimed primarily at structural performance, a clay cap also must achieve
a very low in situ permeability—the lower the permeability to water, the more impervious the
cap. Usually, this cap is a 2-ft or thicker clay layer placed on top of the backfill. Construction
of an impervious clay cap is a labor-intensive process with stringent engineering requirements.
Construction of a sufficiently impervious cap demands well-specified methods and material
selection practices, and results must be verified by in situ testing.
The placement of a 2-ft-thick native soil and topsoil layer above the cap will protect it
from excessive changes in temperature and freeze-thaw cycles, which can compromise its
integrity. This alternative would entail placing an estimated 90,000 yd3 of compacted fill, clay,
grading materials, and soils over the existing empty impoundments for filling, contouring, lining,
drainage control, and revegetation. This alternative would require that the water from the
K-1407-B Pond be treated at the CNF but would not generate by-product wastes that require
management.
Alternative 4 meets DOE Orders 5400.5 and 5820.2A with regard to exposure limits and
the long-term management of residual radioactive contamination left in place, RCRA clean
closure requirements (40 CFR 265), and floodplain/wetlands regulations [10 CFR 1022 and 40
CFR 6 (Appendix A)], as described in Alternatives 2 and 3. Alternative 4 utilizes the NCP
hybrid closure guidance [52 FR 8712 and 53 FR 51446]. The NCP hybrid closure guidance
makes use of RCRA [40 CFR 265.228 (a)(2)J requirements for closure with waste in place, i.e.,
closure and post closure care requirements. These are considered TBC guidance for
implementation of a modified RCRA cap in the instance where no hazardous waste remains.
Capital cost: $6.3 million
Annual O&M cost: $33,000
Present worth cost over 30 years: $6.8 million
Months to implement: 15
D93021S.4PSS1 2-69 09/24/93
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Alternative 5—Five-Component Cap
EPA provides detailed technical guidance for the design of this type of cap, as explained
in the RI/FS document. A composite five-component cap is very impervious and would be a
conservative means of isolating the remaining contaminants. The cap is designed in five parts,
each having a specific function to enhance the cap's reliability. The cap includes a composite
clay and synthetic liner impervious layer, which enhances the effectiveness of clay. This
membrane, also called a flexible membrane liner, is a continuous sheet of a synthetic polymer
impervious to gas and liquids. A five-component cap requires specialized personnel for
installation and must comply with demanding performance standards. This type of cap is used
mostly on landfills or where a closure with waste in place is planned from the inception. It is
intended as the "lid" for zero discharge waste disposal sites, where waste is completely isolated
from the environment. Its effectiveness for this site is very similar to that of Alternative 4.
This alternative would entail placing an estimated 90,000 yd3 of compacted fill, clay and
grading materials, and soils over the existing empty impoundments for filling, contouring, lining
and drainage control, and revegetation. An estimated 180,000 ft2 of composite cap would be
installed. Material for drainage and filter layers would be needed—possibly 6,000 yd3 of natural
materials or 360,000 ft2 of geosynthetic materials. This alternative does not generate by-product
wastes.
Alternative 5 meets DOE Orders 5400.5 and 5820.2A requirements regarding exposure
limits and the long-term management of residual radioactive contamination left in place, RCRA
clean closure regulations (40 CFR 265), and floodplain/wetlands requirements [10 CFR 1022 and
40 CFR 6 (Appendix A)], as described in Alternatives 2 and 3. Alternative 5 also utilizes the
NCP hybrid closure guidance (52 FR 8712 and 53 FR 51446) and RCRA requirements for an
impervious cap [40 CFR 265.228 (a)(2)]; these are considered TBC guidance.
Capital cost: $8.4 million
Annual O&M cost: $52,000
Present worth cost over 30 years: $9.1 million
Months to implement: 15
Alternative 6—Excavation and Treatment
Excavating the contaminated soils would involve removing a few feet of soil from the side
slopes and the bottoms of the K-1407-B/C Ponds. The soil matrix would then be immobilized
through fixation in a free-standing solid to allow storage, minimize contaminant mobility, and
reduce the health risk associated with the fixed waste. The technology of fixation by means of
Portland cement and a sorbent was assumed for the cost estimate, but any applicable technology
may be used. A different system would not necessarily entail the same costs estimated here.
D9302I5.4PS5I 2-70 09/24/93
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This alternative is a contingent plan for the remediation of the ponds; if other actions prove
infeasible, it would be reconsidered. If this alternative is selected, treatability and the extent of
contamination will need further investigation. After removal, the excavation would be backfilled
to reclaim the use of the surface. Engineered compacted fill would be acceptable and suitable
for backfilling.
The exact volume of contaminated soils to be excavated is uncertain. The excavation and
solidification of an estimated 21,000 yd3 of contaminated soils was assumed. This volume of soil
would generate an estimated 30,000 yd3 of solidified, low-level waste by-product for long-term
storage. Management of this waste is a long-term liability that is difficult to evaluate.
Backfilling involves placing at least 70,000 yd3 of clean fill, depending on surface runoff control
and the volume of fill required to restore the site.
Alternative 6 meets RCRA clean closure regulations (40 CFR 265), and
floodplain/wetlands requirements [10 CFR 1022 and 40 CFR 6 (Appendix A)], as described in
Alternatives 2 and 3. Alternative 6 would remove the source of contamination, meeting
compliance with DOE Order 5400.5 requirements for exposure limits and the requirements for
management and disposal of waste containing residual radioactive contaminants in 5400.5,
Chapters II and IV, and 5820.2A. A storage area for the excavated soil is available on-site (DOE
Orders 5400.5 and 5280.2A). Stormwater runoff controls (40 CFR 122, TCA Sect. 1200-4-3)
and fugitive dust controls (TCA Sect. 1200-3-8.01) would be implemented.
Capital cost: $13 million
Annual O&M cost: $30,000
Present worth cost over 30 years: $13.4 million
Months to implement: 15
D930215.4PS51 2-71 . . 09/24/93
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SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
EPA has established nine evaluation criteria as described in Guidance for Conducting
Remedial Investigations and Feasibility Studies Under CERCLA (EPA 1988b) for the evaluation
of remedial alternatives at CERCLA sites. These nine criteria are organized into three groups:
• Threshold Criteria—These criteria relate to statutory findings and address (1) overall
protection of human health and environment and (2) compliance with ARARs.
• Primary Criteria—These criteria address the performance of the remedial alternative.
They also verify that the alternative is realistic. The primary criteria are (3) long-term
effectiveness and permanence; (4) reduction in toxicity, mobility, or volume through
treatment; (5) short-term effectiveness; (6) implementability; and (7) cost.
• Modifying Criteria—The viability of the solution is evaluated based on (8) state
agency acceptance and (9) community acceptance.
Threshold Criteria
Overall Protection of Human Health and the Environment—The assessment against this
criterion describes how the alternative as a whole achieves and maintains protection of human
health and the environment.
Compliance with ARARs—The assessment against this criterion describes how the
alternative complies with ARARs or, if a waiver is required, how it is justified. The assessment
also addresses other information from advisories, criteria, and guidance that the lead and support
agency have agreed is TBC.
Primary Criteria
Long-Term Effectiveness and Permanence—The assessment of alternatives against this
criterion evaluates the long-term effectiveness of alternatives in maintaining protection of human
health and the environment after response objectives have been met.
Reduction of Toxicity, Mobility, or \blume Through Treatment—The assessment against
this criterion evaluates the anticipated performance of the specific treatment technologies an
alternative may employ.
Short-Term Effectiveness—The assessment against this criterion examines the effectiveness
of alternatives in protecting human health and the environment during the construction and
implementation of a remedy until response objectives have been met.
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Implementability—This assessment evaluates the technical and administrative feasibility
of alternatives and the availability of goods and services.
Cost—This assessment evaluates the estimated capital, O&M costs, and present worth cost
for a life of 30 years of each alternative in 1991 dollars. The estimates are order of magnitude
estimates that necessarily incorporate many assumptions. Although they are also useful for
comparing alternatives, the uncertainty associated with them is significant.
Modifying Criteria
State Acceptance—This assessment reflects the state's apparent preferences or concerns
about alternatives.
Community Acceptance—This assessment reflects the community's apparent preferences
or concerns about alternatives.
The six remedial alternatives considered for the K-1407-B/C Ponds are evaluated against
the nine CERCLA evaluation criteria in the following discussion. A summary comparison of the
seven threshold and primary criteria against the six alternatives is presented in Table 2.16.
Overall Protection of Human Health and the Environment
Alternative 1, No Action, is not protective of and offers no reduction in risks to human
health or the environment. Alternatives 2 through 5 provide protection from exposure to the
contaminants remaining on-site through shielding and the management of contaminant migration.
These alternatives do not remove the residua] contamination but limit its effects through isolation.
Alternative 6 protects human health and the environment at the K-1407-B/C Ponds site through
source control by removal of the contaminants, but generates additional risks to human health and
the environment associated with the removal, handling, and long-term storage of waste.
Alternative 6, while reducing risk at the site-specific level, results in a transfer of risk and,
therefore, may not represent an overall risk reduction.
For both the general plant employee and the on-site worker risk scenarios, the completed
exposure pathways considered in the baseline risk assessment for the K-1407-B/C Ponds were
ingestion of, dermal contact with, and inhalation of wind-generated dust. The general plant
employee scenarios additionally included external exposure to radiation in dust; the on-site worker
scenario additionally included exposure to ionizing radiation. Implementation of any of
Alternatives 2 through 6 will effectively eliminate all these exposure pathways and the associated
risk to receptors. Therefore, for the general plant employee and the on-site worker risk
scenarios, Alternatives 2 through 6 are equally protective. The potential difference between the
alternatives for overall protection of human health and the environment arises only for protection
D930215.4PS51 2-73 09/24/93
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Table 2.16. Evaluation of alternatives for remediation of the K-1407-B/C Ponds
No.
1
2
3
4
5
6
Alternative
No Action
Engineered Rock Fill
Engineered Fill
Backfill and Clay Cap
Five-Component Cap
Excavation and Treatment
Protection
0
/
/
/
/
/
ARAKs
o
/
/
/
/
/
Effective-
ness
N/A
/
•
•
•
/
Reduction
by treatment
N/A
N/A
N/A
N/A
N/A
O
Short-
term
N/A
/
/
/
/
•
Implement-
ability
N/A
/
/
/
/
/
Cost
N/A
/
•
•
•
•
= Unsatisfactory
= Intermediate
N/A = A'or Applicable
-------
offered to the hypothetical future on-site resident in the comparison of Alternatives 2 through 5
with Alternative 6.
Completed exposure pathways considered in the baseline risk assessment for the on-site
resident risk scenario at the K-1407-B/C Ponds were ingestion of soil, dermal contact with soil,
inhalation of wind-generated dust, external exposure to soil radiation, ingestion of groundwater,
dermal contact with groundwater while showering, inhalation of volatiles while showering, and
ingestion of homegrown produce. Total excess cancer risks estimated in the baseline risk
assessment for the on-site resident are 1 x 10'2 and 7 x 10'3 for the K-1407-B and K-1407-C
Ponds, respectively.
Alternatives 2 through 5, although different in terms of engineering design, are equal in
the protection of human health and the environment. Because Alternative 6 represents source
control by removal of the contaminants, there are different ramifications for overall protection
for the on-site resident than for Alternatives 2 through 5. In evaluating the true effectiveness of
Alternative 6, it is necessary to evaluate (1) the reduction of risk that would occur as a result of
its implementation, (2) the chance that baseline risk conditions for the on-site resident could be
realized at the site in the future, and (3) the additional risks generated by implementation of the
alternative.
Alternative 6 would eliminate the potential for cross-contamination and migration of
contaminants from the pond soils in groundwater at the K-1407-B/C Ponds site. However, the
analysis of contaminant migration, based on the comparison of data for K-1407-B/C Pond soils
and monitoring wells and the computer-simulated modeling indicate that there is very little risk
associated with migration of contaminants in the groundwater from the pond soils. Groundwater
migration of contaminants from the K-1407-B/C Pond soils into groundwater does not appear to
represent a significant risk even for the most conservative assumptions. Accordingly, the
excavation of residual soil contamination under Alternative 6 would not result in a meaningful
reduction of risk for groundwater pathways for the on-site resident scenario.
The protection afforded by Alternative 6 would be primarily from the elimination of direct
exposure to ionizing radiation and the elimination of contact to contaminants in the soil for all
exposure pathways by removing contamination. However, the true protection provided by
excavation and removal under this alternative must take into account the realistic probability of
future exposure to baseline risks at the site. The conservative approach to evaluating the
maximum risk to human health for future scenarios is to assume that a future on-site resident
could reestablish baseline conditions and thereby be exposed to baseline risks at the site.
However, if the ponds were filled, this would be highly unlikely to occur even with residual soil
D9302IS.4PS51 2-75 09/24/93
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contamination left in place; a combination of highly improbable events would be necessary to
reestablish baseline conditions.
To reestablish baseline conditions at the site, the future on-site resident would have to
excavate the pond(s) to its original depth to build a residential structure and plant a garden. For
the K-1407-B Pond, this would involve excavating to a level below the water table and through
many feet of rock fill that would be present from the implementation of the proposed remedy for
the site. For both the K-1407-B and K-1407-C Ponds, placing a house below the 100-year flood
plain would be required.
Even assuming such construction activities were to occur, the level of excavation would
have to coincide almost perfectly with the current level of the pond bottoms for the on-site
resident to be exposed to baseline risk conditions. To be exposed to the total risks from ingestion
of homegrown produce, the root systems of crops would have to be situated within a narrow 1-ft
zone of maximum contaminant concentration. Even if the considerable obstacles were overcome
to build a residential structure and plant a garden in the original pond bottoms, crops probably
could not grow because of the poor agricultural nature of the soils.
The construction of a single-level residential structure in either the K-1407-B or -C Pond
would in all likelihood involve the excavation of no more than a few feet of soil. Based on the
proposed thickness of pond fill, an excavation of such a depth would not reach the site's soil
contamination and, therefore, would not result in the completion of the soil exposure pathways
considered in the baseline risk assessment for the on-site resident. The construction and
occupancy of a basement home could create a greater potential for exposure to soil contaminants
at the site than a single-story dwelling. However, occupancy of such a structure would not
approximate baseline risk conditions because shielding offered by the walls and floor of the
basement area would eliminate or drastically reduce soil pathways.
Aside from the practical and physical obstacles to reestablishing baseline conditions at the
site in the future, the role of institutional controls must be considered. Realization of the
hypothetical future on-site scenario must assume that there would be unlimited use of the site if
institutional controls were lifted. However, it is reasonable to assume that institutional controls
will be in force at the site as long as it is held by DOE. Furthermore, DOE's future release of
any property, particularly property with residua] contamination, would carry restrictions
regarding the use of the land, and any property transfer will follow the procedure outlined in the
FFA (DOE 1992d), Sect. XLIII, Property Transfer. Because of their widespread acceptance and
enforceability, future restrictions to land use warrant consideration of their ability to limit future
exposure to residual site contamination. The institution of such legally binding obligations would
D9302154PSJ1 2-76 09/24/93
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serve to further reduce the likelihood of future human exposure to residual contamination at the
site.
In assessing the overall protectiveness of Alternative 6, it is important to recognize that
the removal of residual soil contamination from the K-1407-B/C Ponds would not resolve the
issue of institutional control for waste generated from the site. Because no effective technology
for the detoxification of radioactive material exists, the exhumation of the residual radiological
contamination from the bottom of the K-1407-B/C Ponds and its transformation into a different
form of waste would suffer from the same complications associated with institutional controls at
the ponds site. To protect public health and the environment, it would be much safer for residual
radiological contamination to remain at the bottom of the ponds, below 10 ft of soil cover, than
to be stored in any manner above surface should institutional controls fail at some future time.
Accordingly, there are greater potential problems associated with institutional controls for the
storage of the exhumed waste above surface than for residual contamination left in place.
Alternative 6 does not offer advantages for the overall protection of human health and the
environment when compared to Alternatives 2 through 5 because (1) it is extremely improbable
that baseline conditions could ever be established at the K-1407-B/C Ponds at any time in the
future even in the absence of institutional controls, (2) there is the high likelihood that
institutional controls will prevail at the site even in the case of property transfer, and (3) the
excavation, handling, and long-term storage of waste will generate a potential risk to human
health and the environment. Conversely, the implementation of Alternative 6 could actually
result in an increase of risk, especially in the absence of institutional controls for the long-term
storage of waste at the surface.
In summary, Alternatives 2 through 5 provide protection at least equal to Alternative 6
for all human risk scenarios.
Compliance with ARARs
There are no chemical-specific ARARs for the cleanup of contaminated soils at the
K-1407-B/C Ponds associated with any of the alternatives. There arc several location-specific
and action-specific ARARs pertinent to the remediation of the ponds that are associated with all
the alternatives as shown in Table 2.17.
The ponds are located within the 100-year and 500-year floodplain areas. Therefore,
location-specific federal and state ARARs for the protection of floodplains are applicable to all
alternatives and must be met for any remedial activities taken in the K-1407-B/C Ponds area.
The wetlands survey conducted for the site indicated that no wetlands areas are present in the
K-1407-B/C Ponds; concurrence with this finding is expected from USAGE. However, if any
D9302I5.4PS5I 2-77 09/24/93
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Table 2.17. Comparison of compliance for each alternative for the K-1407-B/C Ponds with ARARs and TBCs
Regulations and guidance
ARAR TBC Alternative I Alternative 2 Alternative 3 Alternative 4
No action Engineered Engineered fill Backfill and
rock fill clay cap
Alternative 5
Five-
component
RCRA cap
Alternative 6
Excavation and
treatment
to
-!j
oo
Radiation Protection of the Public and
Environment:
DOE Order 5400.5
Long-term management of residual
radioactive contaminants left in place:
DOE Order 5400.5 Chapter II and IV,
DOE Order 5820.2A
Floodplain protection:
10 CFR 1022, and 40 CFR 6
(Appendix A)
Wetlands protection:
10 CFR 1022, and 40 CFR 6
(Appendix A)
Removal or decontamination of all waste
residues and contaminated subsoils at
interim status surface impoundments:
40 CFR 265.228(a)(l);
TCA §1200-1-1 l-.05(ll)(g-l)
RCRA closure and postclosure care
requirement:
40 CFR 265.228(a)(2)
NCP hybrid closure guidance*1
On-site construction/excavation:
Control of fugitive dust emissions:
TCA §1200-3-8.01
Surface water control:
40 CFR 122, TCA §1200-4-3
N/P
N/P
N/P
N/P
N/P
N/P
N/P
N/P
N/P
-------
Table 2.17 (continued)
Regulations and guidance
ARAR TBC Alternative I
No action
Alternative 2 Alternative 3 Alternative 4 Alternative 5 Alternative 6
Engineered Engineered fill Backfill and Five- Excavation and
rock Till clay cap component treatment
RCRA cap
Stormwater discharges associated with
construction activity at industrial sites
(disturbed site is 5 acres or more):
TCA §1200-4-10-.05
Stormwater discharges associated with
industrial activities: 40 CFR 122, TCA
§!200-4-IO-.04
N/P
+ =meets ARAR or TBC guidance -=does not meet ARAR or TBC guidance N/P=not pertinent
*=The wetlands survey conducted for the site indicated that there are no wetlands areas present at the K-1407-B/C Ponds and the USACE is expected to concur with
this finding. However, if wetlands were determined to be present at the site, then ARARs pertaining to wetlands would be met.
ARAR = applicable or relevant and appropriate requirement
CFR = Code of Federal Regulations
FR = Federal Register
TBC = to be considered
TCA = Tennessee Code Annotated
TDEC = Tennessee Department of Environment and Conservation
USACE = U.S. Army Corps of Engineers
'DOE, while not ARARs, are treated as TBC guidance and/or criteria.
'This hybrid closure TBC guidance comes from the proposed rule found in 52 FR 8712 and discussed as an option in 53 FR 51446. RCRA also implies that the same
type of hybrid closure is acceptable [40 CFR 265.228 (a) and (b)].
8
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wetlands were present at the site, they would be destroyed by the implementation of Alternatives
2 through 6. In this case, mitigative measures would be taken to enhance other wetlands areas
so no net loss of wetlands would occur, thus meeting 10 CFR 1022 and 40 CFR 6 (Appendix A).
The action-specific ARARs for closure of the ponds includes 40 CFR 265.228(a)(l),
which details the requirements for RCRA clean closure and applies to all alternatives. There are
several action-specific ARARs that apply to the construction and implementation of Alternatives
2, 3, 4, 5, and 6. These include Tennessee state regulations and Clean Water Act regulations
requiring that surface water runoff and stormwater discharge during construction activities at
industrial sites be controlled and monitored; the surface water runoff must meet the substantive
requirements of the state stormwater discharge permit. Tennessee regulations also require that
fugitive dust emissions be controlled during site construction and excavation. DOE orders, while
not regarded as ARARs, are treated as TBC guidance and/or criteria.
Nuclear Regulatory Commission (NRC) regulations are not considered applicable for
CERCLA remediation of DOE facilities but are considered potentially relevant and appropriate.
However, none of the NRC regulations are relevant and appropriate for the proposed remedial
action at the K-1407-B/C Ponds. For the purposes of this closure, DOE Order 5400.5, Radiation
Protection of the Public and the Environment, must be met. Under this DOE order, the remedial
action may be considered a restricted closure if residual radioactive contamination remains in
place. If unconditional release of the property becomes a possibility in the future, any property
transfer will follow the procedure outlined in the FFA (DOE 1992d), Sect. XLIII, Property
Transfer.
While the no-action alternative meets the location- and action-specific ARARs, it clearly
does not meet DOE orders for radiation protection. Alternatives 2, 3, 4, 5, and 6 comply with
all the location-specific and action-specific ARARs (see Table 2.17 and the Description of
Alternatives section of this report). Compliance with ARARs and TBCs for Alternative 2, the
selected remedy for the K-1407-B/C Ponds, is further discussed in the Selected Remedy,
Compliance with ARARs and TBCs section of this report.
Long-Term Effectiveness and Permanence
Alternative 1 provides no long-term effectiveness, but present conditions at the
K-1407-B/C Ponds are not likely to worsen in the long-term if no action is taken. Risk due to
airborne contamination may actually be reduced by further growth of vegetation. The risks posed
by 137Cs and "Tc will naturally abate through radioactive decay and dilution within the soil
horizon. This natural abatement would result in the reduction of risk at the site by a full order
of magnitude (to 3 x 10"3) over a 100-year span. However, the baseline risk assessment
conducted for the K-1407-B/C Ponds shows that the hypothetical on-site resident who lives on-site
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for 30 years (the national upper-bound residency term for baseline risk assessment estimates) is
estimated to have 1 chance in SO of developing cancer from exposure to contaminants present on-
site (risk of 2 x 10'2). Alternative 1 does not provide any reduction of this risk to human health
or the environment and, therefore, is unacceptable.
Engineering controls proposed under Alternatives 2, 3, 4, and 5 would effectively
deactivate all the direct exposure and soil pathways of exposure identified in the baseline risk
assessment to all receptors. All existing exposure pathways and all risk associated with each
pathway would be eliminated. The effectiveness of the fill/cap remedies is evidenced by
RESRAD computer modeling conducted as part of the RI/FS for the K-1407-B/C Ponds. The
RESRAD computer code was developed as a compliance tool to develop residual contamination
guidelines at DOE facilities. RESRAD modeling conducted for the K-1407-B/C Ponds indicated
that the protection offered by the engineered fill option would be sufficient to maintain exposure
levels within DOE guidelines for at least 10,000 years (the maximum span for which the model
was run), even without maintenance. For the foreseeable future, the integrity of the fill/cap
options would be enhanced by regular surveillance and maintenance as part of ongoing operations
at the K-25 Site.
Rock fill incorporated as a stable subgrade as part of Alternative 2 would not be
compromised by time or by long-term exposure to groundwater. The soil cover above the rock
fill would be graded for effective drainage and vegetated, and would enhance the effectiveness
of the rock fill as a means to deactivate pathways of exposure. Hence, the soil cover would add
to the reliability of this alternative and to its effectiveness.
Risks to the hypothetical future on-site resident subsequent to the implementation of
Alternative 2 are estimated to be negligible because all exposure pathways, with the exception
of groundwater-related pathways, would be eliminated because (1) contaminated dust will no
longer be generated, (2) roots of homegrown garden produce are not expected to extend into the
contaminated layer, and (3) the alternative will effectively shield individuals from external
exposure to ionizing radiation. Excess cancer risk subsequent to the implementation of
Alternative 2 would be below the EPA threshold of concern (< 1 x 10"6). Systemic toxicity after
remediation would be absent and background conditions would be reestablished.
PRGs for reducing risk to acceptable levels would be met by reducing the exposure of
potential human receptors to contamination, as opposed to reducing the level of contamination;
the contaminants would remain in place, but the exposure pathways would be eliminated. After
placement of clean fill material, the level of exposure to contamination for the potential human
receptor, including the on-site resident, would be no greater than background.
D9302I5.4PS51 2-81 09/24/93
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External exposure to ionizing radiation would be reduced to background levels by physical
shielding of the radionuclides in the pond soils with the fill material. Intake of contaminants by
way of produce ingestion would be eliminated because the roots of plants grown for food will not
extend through fill material to reach the contaminated pond soils. Incidental ingestion of
contaminated soils and inhalation of contaminated soils as dust would not be possible because
the soils will be inaccessible.
The only potential negative ecological impact subsequent to the implementation of
Alternative 2 is the possibility of phytotoxicity from plant uptake of contaminants present in the
substrate. The application of clean backfill is expected to provide a sufficient barrier to root
uptake of contaminants by grasses and shrubs. However, this barrier may not be sufficient to
prevent root uptake of some contamination by trees.
Similar to the rock fill under Alternative 2, engineered fill of Alternative 3 is not subject
to significant long-term subsidence, and any settling of the foundations would probably be
manageable. Surface vegetation would help to minimize erosion of the cover, thereby preserving
the contour of the graded surface and drainage conditions. However, engineered fill is not an
impervious medium, and infiltration and percolation do occur. Post-remediation conditions and
residual risk for Alternative 3 is comparable to that of Alternative 2.
The long-term preservation of effectiveness for Alternative 4 appears possible with
minimum regular maintenance. Original drainage conditions would be maintained and the
presence of a hydraulic barrier provided by the clay cap would reduce surface water infiltration
and percolation rates. The addition of this hydraulic barrier would be expected to eliminate the
percolation of meteoric water through the vadose zone. However, because of the low potential
for contaminant migration indicated by the RI/FS, the elimination of surface water infiltration is
not viewed as an advantage in reducing the migration of contaminants through groundwater
exposure pathways at the site. Furthermore, there would be little conceivable advantage in
reducing surface water infiltration at the K-1407-B Pond where the residual contamination is
found mainly below the water table. It is assumed that no improvement to the risk to human
health and the environment at the site is derived from the construction of an impervious barrier,
as compared to the reduction already achieved by Alternatives 2 and 3. Therefore, post-
remediation risk for Alternative 4 is comparable to that of Alternatives 2 and 3.
Alternative 5 offers a potential increase in long-term reliability with the implementation
of a five-component RCRA cap. Initial excellent drainage conditions provided by the system
would be maintained; the presence of a composite impervious liner completely eliminates
infiltration and percolation. However, reservations about the usefulness of a hydraulic barrier
D930215.4PS51 2-82 09/24/93
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at the site are the same as for Alternative 4. The residual risk exposure associated with
Alternative 5 is equivalent to that of Alternatives 2, 3, and 4.
Under Alternative 6, the excavation of radiologically contaminated soil would eliminate
the source of toxicity at the ponds site. It can be assumed that residual risk at the site would be
reduced to acceptable levels. However, there is no currently available technology for the
effective treatment of residual radioactive waste such as found at the K-1407-B/C Ponds. Any
treatment would subsequently require storage of waste by-products. This generates an onerous
long-term commitment and the potential necessity of further treatment.
This alternative would generate risks associated with the excavation, handling, and long-
term storage of waste. Alternative 6, therefore, has the net effect of transferring, rather than
reducing, risk associated with residual contamination from the K-1407-B/C Pond soils. The long-
term effectiveness and permanence for the K-1407-B/C Pond site under Alternative 6 would be
good. However, the long-term effectiveness and permanence for the by-product waste is
considered to be poor; the need would be created for storage, handling, and possibly additional
treatment in the future. In terms of ecological risk, Alternative 6 would be somewhat better than
Alternatives 2 through 5; however, the existing risk to ecological receptors at the site is
considered to be negligible.
Although engineering controls would effectively deactivate all direct exposure pathways
and soil pathways of exposure at the K-1407-B/C Ponds, some CERCLA hazardous substances
would remain on-site for Alternatives 2, 3, 4, and 5. Therefore, these alternatives would be
subject to the 5-year review period mandated in Sect. 121(c) of SARA and Sect. 105 of CERCLA
40 CFR 300.430, Final Remedy Selection. This review would be augmented by data provided
from post-remediation groundwater monitoring to be conducted at the K-1407-B/C Ponds
subsequent to implementation of the remedial action.
Reduction of Toxicity, Mobility, or Volume Through Treatment
Alternative 1, no action, does not employ treatment or confinement of contaminants and
achieves no direct or immediate reduction of toxicity, mobility, or volume of contamination.
With time, the toxicity of the residual contamination in the K-1407-B/C Pond soils would be
reduced by radioactive decay and dilution of contaminant concentrations in soils, and the
migration of airborne contamination might be reduced by the spontaneous growth of vegetation.
Alternatives 2 through 5 involve the placement of fill into the existing impoundments;
Alternatives 4 and 5 additionally include the emplacement of caps over the fill. No reduction of
toxicity, mobility, or volume of residual soil contamination is achieved through treatment for
these alternatives. However, mobility is reduced by physical means of confinement of the
D930215.4PS51 2-83 - (W24W3
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contaminated soils. There are varying implications for Alternatives 2 through 5 for the
infiltration of surface waters and the associated potential for leaching of contaminants for the
K-1407-B/C Ponds.
Alternative 3 offers a reduction in surface water percolation rates for the K-1407-B Pond
compared to Alternative 2 because the soil fill subgrade for Alternative 3 would be less conducive
to infiltration than the rock fill subgrade of Alternative 2. Alternative 4 and 5 would reduce
surface water infiltration at both ponds compared to Alternatives 2 and 3; surface water
infiltration would be curtailed by means of an impervious cap or liner. Therefore, Alternative
3 would offer a reduction in the infiltration of surface waters and the associated potential for
leaching of residual soil contaminants when compared to Alternative 2 for the K-1407-B Pond,
and Alternatives 4 and 5 would eliminate this potential altogether for both ponds.
However, the analysis of contaminant migration conducted as part of the K-1407-B/C
Ponds RI/FS indicates a limited potential for leaching and migration of residual soil contamination
at the site. Accordingly, surface water leaching of soil contaminants and the resultant
contribution to groundwater contaminant migration is not viewed as posing any significant
potential for the contaminant migration. The reduction of surface water infiltration by the
emplacement of an impervious cap or liner would not result in a meaningful reduction in
contaminant migration. Furthermore, the reduction of surface water infiltration at the K-1407-B
Pond would be meaningless since most of the contaminated soil is below the water table.
Alternative 6 would achieve a reduction in the volume of contaminated soils at the
K-1407-B/C Ponds by excavation and removal and would reduce or eliminate the issues of
mobility and toxicity for the ponds site. However, the excavated by-product waste would be
toxic, and there is no currently available method to effectively reduce the toxicity of residual
radiological contamination such as that found at the K-1407-B/C Ponds. Treatment of excavated
waste would pursue reduction of mobility through fixation. Such fixation would result in the
generation of a considerably greater volume of low-level residual waste than that initially
excavated. The waste properties would be irreversibly altered and thereby nullify the presently
existing threat posed by the contaminants. However, a different type of waste with toxic
properties would be created in quantities greater than those of the original waste. The excavation
and fixation of the estimated 21,000 yd3 of contaminated soils would likely result in no less than
30,000 yd3 of solidified low-level radioactive waste.
Because of the lack of available technology, the alternatives proposed for remediation of
the K-1407-B/C Ponds do not use treatment as a means to reduce the principal threat at the site.
Therefore, management of in situ residues is a more appropriate remedy for this site.
D9302154PS51 2-84 09/24/93
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Short-Term Effectiveness
Alternative 1, no action, would present no short-term risks in excess of baseline risk
conditions estimated for the site. The implementation of Alternatives 2 through 6 would result
in increased risk to human health and the environment related to construction, hauling, and
treatment activities.
It is estimated that the implementation of Alternative 2 would require about three months
of consecutive work days of suitable weather conditions, or the equivalent, for the completion
of construction activities, with some variation for Alternatives 3 through 5 based on the
complexity of the alternative. The short-term effectiveness of these alternatives is similar. In
the short term, there is a possibility of negative cross-media impacts. During and after
construction, the foundation of the ponds could undergo limited consolidation and settlement.
The overburden imposed by the weight of the fill would compress pond subsoils, possibly causing
pore water to spread.
Part of the contaminated pore water trapped in these soils, especially in the K-1407-B
Pond, could be released to the environment, causing a temporary increase in contamination of
surface water in the impoundments. The release of contaminated pore water could also cause a
temporary increase in contaminant migration in the groundwater. However, any increase in
contamination of surface or groundwater is expected to be temporary, limited to the immediate
pond areas, and not to pose a significant threat to human health or the environment.
The implementation of Alternatives 2 through 5 would also require the transport of
significant quantities of borrow materials. Road-related risk for the truck drivers hauling the fill
material to the ponds site is evaluated at 1 chance in 1000 for death and 6 chances in 100 for
injury. Because of the secluded setting of the ponds, there is no direct risk to the community
during implementation of these remedial alternatives except for the increase in truck traffic
between the ponds site and the designated borrow area. Risk to the community would be limited
by normal traffic and hauling safety precautions.
Excess lifetime cancer risk to remediation workers has been quantified at 2 x 10's (20
chances in 1 million) under the following assumptions: (1) the remedial worker is exposed for
8 months to representative concentrations of contaminants in soils for 8 n/day, 5 days/week; (2)
personal protective equipment (PPE) is used; (3) external exposure to ionizing radiation is a
complete exposure pathway, but dermal contact, inhalation and ingestion of dust, and ingestion
of groundwater are not; and (4) the shielding effect of progressive backfilling is not considered
(which is an extremely conservative assumption). The estimated risk of 2 x 10'5 is within the
range of acceptable exposure according to EPA, and the actual risk is expected to be substantially
lower.
D93Q215.4PS5I 2-85 09/24/93
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The possibility of short-term cross-media impacts exists for the implementation of
Alternative 6. Significant volumes of contaminated soils would be excavated and would need
temporary storage before treatment. Also, mounds of contaminated soils allowed to air dry might
temporarily affect air quality in the vicinity of the workplace. Backfilling would occur with the
associated risk estimated for Alternatives 2 through 5.
From a risk standpoint, significant amounts of dust could be generated and exposure from
inhaling or ingesting contaminated airborne dust would increase potential risk to the on-site
worker. These potential risks would be mitigated by the employment of appropriate techniques
for dust control and the donning of proper PPE. The wearing of appropriate PPE by on-site
remediation workers would effectively eliminate dermal absorption and inhalation of contaminants
present on-site. Groundwater is not currently used by the on-site worker, and ingestion of
contaminated groundwater is not considered a complete exposure pathway to the remediation
worker.
Alternative 6 would require a greater duration and level of on-site activity than
Alternatives 2 through 5. However, risks to the on-site remedial worker for the implementation
of Alternative 6 would not be expected to be appreciably greater than the risks for the
implementation of Alternatives 2 through 5, and the hauling of the additional volume of fill on
area roads would not pose a substantial increase in risk to truck drivers or the community.
For Alternative 6, the ponds would be dewatered and the soils excavated; therefore, the
potential cross-media impacts to surface and groundwater would be less than for Alternatives 2
through 5. It is not expected that the implementation of Alternative 6 would result in an
increased risk to the environment above baseline conditions.
Implementability
All remedial alternatives are based on mature technologies, and their implementation does
not present new technical challenges. The goals projected for each alternative are technically
realistic in the scope of the alternative. The administrative feasibility of these alternatives
depends on the achievement of a consensus among DOE and regulatory agencies involved in the
evaluation and approval process. This will center on compliance with ARARs and the
CERCLA/RCRA approach adopted for this remedial initiative.
The implementation of any of these alternatives would be consistent with future planned
RIs and activities at the site, such as the K-25 Groundwater RI/FS, and would allow continued
monitoring at the site necessary to verify the effectiveness of the remedial alternative.
D9302IS 4PSS1 2-86 W/24/93
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Cost
Alternative 1 involves no cost. The estimated costs increase from $4.5 million for
Alternative 2 to $13.0 million for Alternative 6. Cost is one of the five primary criteria for the
analysis of alternatives under CERCLA and is relevant when choosing among solutions offering
a comparable degree of protection. The estimated increased costs of Alternatives 3 through 6
over the estimated cost of Alternative 2 do not correlate to the protection, permanence, and
advantages provided by these alternatives. The safeguards provided by Alternative 2 comply with
available guidelines to protect human health and the environment in a cost-effective manner.
Table 2.18 shows the cost and present worth cost for Alternatives 2 through 6.
Table 2.18. Cost and present worth for Alternatives 2 through 6
Alternative 2 Alternative 3 Alternative 4 Alternative 5 Alternative 6
Cost $4.5 million $5.5 million $6.3 million $8.4 million $13.0 million
Present worth3 $5.0 million $6.0 million $6.8 million $9.1 million $13.4 million
'Present worth costs over 30 years
For the purpose of cost comparisons, present worth was calculated for a 30-year period
for each alternative. However, the use of this 30-year period does not infer that the site will
necessarily be suitable for release from institutional controls at the end of that period. It is
recognized that institutional controls, consisting of the use of physical barriers, legal restrictions,
or both, will remain as long as unacceptable risks exist at the site. Institutional controls may be
required at the site for a period substantially longer than 30 years.
Regulatory Agency Acceptance
TDEC and EPA have reviewed the alternatives proposed for remedial action at the
K-1407-B/C Ponds and concur with the selection of Alternative 2, Engineered Rock Fill, as the
alternative best suited for remediation of the K-1407-B/C Ponds.
Community Acceptance
No public comments or questions were submitted during the public comment period for
the Proposed Plan for the K-1407-B/C Ponds. By the absence of comments, it is assumed that
the public is in favor of the selection of Alternative 2 as the most appropriate remedial action for
the K-1407-B/C Ponds.
D93021S.4PSS1
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SELECTED REMEDY
Based on the detailed analysis of alternatives against CERCLA requirements, the most
appropriate remedy for the K-1407-B/C Ponds is Alternative 2, Engineered Rock Fill.
Alternative 3 does not achieve objectives as effectively as Alternative 2. Alternatives 4 and 5
represent an increase in cost with no increase in risk reduction to human health or the
environment at the site. Alternative 6 offers no further advantages that justify the added cost or
the long-term health and financial liabilities associated with the handling, treatment, and storage
of waste by-products generated by its implementation. Alternative 2 represents the best balance
of trade-offs of all the alternatives evaluated.
Alternative 2 consists of filling the K-1407-B Pond with an estimated 14,000 yd3 of
crushed rock fill and filling the K-1407-C Pond with an estimated 63,000 yd3 of engineered
compacted soil. These estimates are based on generalized assumptions; actual volumes may vary
significantly during the design and construction phase of remediation. At the K-1407-B Pond,
crushed and graded rock fill will be emplaced and compacted with appropriate equipment. Rock
fill is suited for the waterlogged environment of the K-1407-B Pond because it can be placed
there without difficulty; subgrade stabilization will not be required. Rock fill is also appropriate
for use at the K-1407-B Pond because the low surface activity of the coarse granular material will
limit the potential for chemical fixing of groundwater contaminants onto the fill.
It is expected that water displaced by the emplacement of rock fill into the K-1407-B Pond
will flow away naturally as groundwater, establishing a dry, stable surface above the water table
that will facilitate the placement of the overlying soil cover. Surface grading and contouring will
be accomplished by placing an engineered soil cover above the rock fill. This soil cover will be
separated from the underlying coarser material by a filter, possibly a synthetic geotextile, to
prevent piping. The cover will then be graded to direct drainage away from the pond area.
The K-1407-C Pond will not require a rock fill subgrade because it is not waterlogged.
The K-1407-C Pond will be filled with more cost-effective compacted borrow soil. The borrow
soil will be spread in thin lifts and compacted. Because of compaction and quality control, the
fill will not be subject to significant settlement and, therefore, should require little maintenance.
For both impoundments, revegetation in native soil, and possibly topsoil, will control
erosion and stabilize the soil cover for long-term reliability. No engineering structures other than
those required for surface water runoff and erosion control will be necessary during construction.
Alternative 2 will not generate man-made by-product waste that requires management.
Modifications may be made to this remedy as a result of the remedial design and construction
D9302I5.4PS51 2-88 09/24/93
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process; such changes, in general, would reflect modifications resulting from the engineering
design process.
The baseline exposure pathways considered complete at the K-1407-B/C Ponds for the
genera] plant employee and the on-site worker risk scenarios are dermal contact with, and
ingestion and inhalation of wind-generated dust. The external exposure to radiation in dust
pathway is additionally considered complete for the general plant employee and the direct
exposure to ionizing radiation pathway for the on-site worker. The implementation of
Alternative 2 will effectively eliminate all these baseline exposure pathways and their associated
risks to receptors. After the placement of clean fill material, the level of on-site contamination
to which any potential human receptor would be exposed will be no greater than background.
The contaminants will remain in place, but the exposure pathways will be eliminated. Thus,
risk-based PRGs will be met.
Based on current site conditions, the exposure pathways considered complete for the
hypothetical future on-site resident are ingestion of soil, dermal contact with soil, inhalation of
wind-generated dust, external exposure to soil radiation, ingestion of groundwater, dermal contact
with groundwater while showering, inhalation of volatiles while showering, and ingestion of
homegrown produce. The remediation of groundwater contamination is not addressed as pan of
this remedial action but will be addressed under the K-25 Groundwater OU RI/FS. All other
exposure pathways for the hypothetical future on-site resident will be eliminated by the
implementation of Alternative 2.
Although the contaminants will remain in place, it will be virtually impossible for anyone
in the future to reestablish baseline conditions at the ponds in the attempt of establishing residency
at the site. However, because the continued presence of contamination on-site represents a
potential threat, institutional controls (as already in place at the site) are considered as a
component of this alternative to provide added protectiveness.
Institutional controls, reopeners, and contingencies to ensure that the remedy remains
effective, to be agreed upon with the state, will be implemented. For example, under DOE Order
5400.5, the selected remedy is considered a restricted closure. Therefore, if at any point in the
future unconditional release of the site becomes a possibility, DOE (or its successor) shall conduct
a review of the remedy and current site conditions prior to transfer of the K-25 Site from DOE
(or its successor) to another person or entity. Any property transfer will follow the procedure
outlined in the FFA (DOE 1992d), Sect. XLIII, Property Transfer. Additionally, because this
remedy will result in hazardous substances remaining on-site above health-based levels, a review
will be conducted every 5 years, beginning within 5 years after commencement of the remedial
action, to ensure that the remedy continues to provide adequate protection of human health and
D9302I5.4PS51 2-89 09/34/93
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the environment in accordance with CERCLA 121(c). This review will be augmented by data
available from post remediation groundwater monitoring at the site. Post remediation
groundwater monitoring will be conducted in accordance with the groundwater monitoring plan
for the K-1407-B/C Ponds, which will be finalized upon EPA and TDEC approval.
Flooding would not compromise the remedial action taken at the ponds, meeting 10 CFR
1022 and 40 CFR 6 (Appendix A). Final remediation under Alternative 2 would meet RCRA
clean closure requirements (40 CFR 265). Certification of RCRA clean closure will be
completed before remedial activities are implemented at the site. During construction,
stormwater runoff controls (40 CFR 122, TCA Sect. 1200-4-3) and fugitive dust controls
(TCA Sect. 1200-03-8.01) would be implemented. This alternative will meet the exposure limits
of DOE Order 5400.5 and comply with DOE Order 5400.5, Chapters II and IV, and DOE Order
5820.2A requirements for the long-term management of residual radioactive contamination left
in place. No wetlands areas were identified in the ponds by the wetlands survey conducted for
the site, and concurrence with this finding is expected from the USAGE. If wetlands were
determined to be present at the site, they would be destroyed by this alternative; however,
mitigative measures would be taken to enhance other wetlands areas so no net loss of wetlands
would occur, thus meeting 10 CFR 1022 and 40 CFR 6 (Appendix A).
Furthermore, following remedial construction activities at the K-1407-B/C Ponds, the
K-25 Site Environmental Sites and Exterior Properties organization will (1) conduct periodic site
inspections, radiological and industrial hygiene surveillance, and other assessment activities as
necessary to keep inactive sites in compliance with environmental, safety, and health
requirements, as well as maintain records of all related activities; (2) ensure that site access and
activity controls are established and maintained in compliance with security and environmental,
safety, and health requirements; and (3) implement maintenance activities required as a result of
site inspections, including maintenance of containment systems, monitoring instrumentation, and
facility support equipment, general area upkeep, and grounds maintenance. Surveillance and
maintenance activities for the K-1407-B/C Ponds will follow the Surveillance and Maintenance
Plan for Inactive ER Remedial Action Sites at the Oak Ridge K-25 Site, Oak Ridge, Tennessee,
K/ER-54 (Energy Systems 1993), which describes site inspection activities and the frequency of
the site inspection.
An estimate of the capital cost for a 30-year period for each major component of
Alternative 2 is presented in Table 2.19. The present worth for Alternative 2 was calculated
using an estimated O&M cost of $50,000/year for 5 years and $30,000/year for the next 25 years
with an interest rate of 7% over the entire 30-year period, resulting in a present worth of
$455,000 for the annualized O&M in 1991 dollars.
D930215.4PS51 2-90 09/24/93
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For the purpose of cost estimation, present worth was calculated for a 30-year period for
Alternative 2. However, the use of this 30-year period does not infer that the site will necessarily
be suitable for release from institutional controls at the end of that period. It is recognized that
institutional controls, consisting of the use of physical barriers, legal restrictions, or both, will
remain as long as unacceptable risks exist at the site. Institutional controls may be required at
the site for a period substantially longer than 30 years.
Table 2.19. Capital costs for Alternative 2
Component Cost
Site preparation $81,000
Mobilization and demobilization $28,000
Rock and soil fill $3,295,000
Site restoration $27,000
Engineering costs $100,000
Construction oversight $50,000
15% Contingency at start-up $895.000
Total $4,476,000
D9302I5.4PS5I 2-91 09/24/93
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STATUTORY DETERMINATIONS
Under its legal authority, DOE's primary responsibility at CERCLA sites is to undertake
remedial actions that achieve adequate protection of human health and the environment.
CERCLA Sect. 121 establishes this criterion and other statutory requirements and preferences for
the selection of remedial alternatives. Aside from the mandate to protect human health and the
environment, selected remedial actions must (1) comply with applicable or relevant and
appropriate environmental standards established under federal and state environmental laws unless
a statutory waiver is justified, (2) be cost-effective, (3) utilize permanent solutions and alternative
treatment or resource recovery technologies to the maximum extent practical, and (4) satisfy the
preference for remedies that employ treatments that permanently and significantly reduce the
volume, toxicity, or mobility of hazardous wastes as their principal elements.
Protection of Human Health and the Environment
The selected remedy will reduce risk to the general plant employee and the on-site worker
at the K-1407-B/C Ponds by effectively eliminating all exposure pathways to these receptors.
The ingestion of wind-generated dust, dermal contact with wind-generated dust, inhalation of
wind-generated dust, external exposure to radiation in dust, and direct exposure to ionizing
radiation pathways will be eliminated, thereby eliminating all risks associated with these
pathways. The elimination of these pathways is achieved by physically confining residual
contamination and shielding potential receptors from ionizing radiation in pond soils. Once
Alternative 2 is implemented, the level of exposure to a human receptor would be no greater than
background conditions.
The implementation of Alternative 2 will further eliminate the pathways of ingestion of
soil, dermal contact with soil, and ingestion of homegrown produce, which are considered
completed for the hypothetical future on-site resident. Therefore, once Alternative 2 is
implemented, the level of exposure to the hypothetical on-site resident at surface conditions would
be the same as for the on-site worker and general plant employee, i.e., equal to background
conditions. Although the residual contaminants will remain in place, it will be virtually
impossible for any person in the future to reestablish baseline conditions at the ponds in the
attempt of establishing a residence at the site. However, because the continued presence of
contamination on-site represents a potential threat, institutional controls at the site will be
maintained as a component of this alternative to provide added protection.
Because this remedial alternative does not address groundwater contamination, risks
associated with the potential exposure pathways for the hypothetical future on-site resident of
ingestion of groundwater, dermal contact with groundwater while showering, and inhalation of
D9302154PS51 2-92 09/24/93
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volatiles while showering will not be reduced. The analysis of historical groundwater data
conducted as part of the RJ indicates that there is not a significant potential for migration of
contaminants from the pond soils into groundwater at the site, with the exception of "Tc. This
conclusion is supported by groundwater modeling conducted to augment the analysis of historical
data. Technetium-99, the beta-emitting radionuclide with the greatest level of activity in the
K-1407-B/C Pond soils, is highly mobile in the soil column and has been detected in groundwater
monitoring wells downgradient from the K-1407-B Pond. However, risk associated with
groundwater pathways for "Tc for even the conservative on-site resident scenario are below the
EPA unacceptable range (1 x 10"4) at 3 x 10'5. Furthermore, "Tc in groundwater, along with
many other groundwater contaminants, has shown a trend of steadily decreasing concentrations
subsequent to the removal of sludge from the ponds. Therefore, the potential for migration of
contaminants from pond soils to groundwater is limited, and risks associated with groundwater
exposure pathways at the site do not currently pose a threat to human health or the environment.
The remediation of groundwater contamination and the reduction of risks from associated
exposure pathways will be addressed under the K-25 Groundwater OU RI/FS.
Alternative 2 will also be protective of the environment. Backfilling the ponds will
eliminate contact with the contaminated pond soils by plants and animals. Plants will receive
direct benefit from this remedy in that pond soils that are potentially phytotoxic due to the metals
content will be below the root zones of most plants. Animals will be protected from contaminant
uptake in their diet because plant foods will not be contaminated. Furthermore, animals will be
less likely to burrow into contaminated pond soils when those soils are covered by a considerable
barrier of clean fill material. Therefore, nondietary exposure pathways for animals will be
eliminated. The potential for burrowing to the level of contaminated pond soils is further reduced
at the K-1407-B Pond where a rock fill subgrade will be emplaced.
Subsequent to the implementation of Alternative 2, exposure to site risks will fall below
the EPA range of concern of 1 x 10"6 for carcinogenic risks and below a hazard index of 1 for
noncarcinogenic toxicity. The implementation of this alternative does not pose significant short-
term risks to remediation workers; there is no direct risk to the community; and there is little
potential for negative cross-media impacts. During and after construction, the foundation of the
ponds could undergo limited consolidation and settlement. The overburden imposed by the
weight of the fill would compress subsoils of the ponds, possibly causing pore water to spread.
This could cause a temporary increase in contamination of surface water in the impoundments.
The release of contaminated pore water could also cause a temporary increase in contaminant
migration in the groundwater. However, any increase in contamination of surface or groundwater
is expected to be temporary and limited to the immediate pond areas and should pose no
significant threat to human health or the environment. Therefore, the implementation of
Alternative 2 generates no unacceptable short-term risks or cross-media impacts.
D930215.4PS5! 2-93 09/24/93
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Compliance with ARARs
Alternative 2 will comply with all the ARARs and TBCs. Table 2.20 provides a summary
of the ARARs and TBCs pertinent to the remedial action at the K-1407-B/C Ponds.
The selected remedial action meets the exposure limits of DOE Order 5400.5, "Radiation
Protection of the Public and the Environment," which is TBC for this remedial action, and it also
meets DOE Order 5400.5, Chapters II and IV, and DOE Order 5820.2A, which address long-
term management of residual radiological contamination left in place. However, the K-1407-B/C
Ponds will be revisited by DOE or its successor with regard to residual radiological contamination
if unconditional release of the property becomes a possibility in the future, and any property
transfer will follow the procedure outlined in the FFA (DOE 1992d), Sect. XLIII, Property
Transfer.
No adverse impact to the floodplain will occur. RCRA clean closure will be achieved by
implementing the selected remedial action. Certification of clean closure will be completed
before remedial activities are implemented at the site. During construction, measures will be
taken to control stormwater runoff, fugitive dust emissions, and exposure to on-site workers as
required by federal and state law. No wetlands areas were identified in the ponds by the wetlands
survey conducted for the site, and concurrence with this finding is expected from the USAGE.
If wetlands were determined to be present at the site, they would be destroyed by this alternative;
however, mitigative measures would be taken to enhance other wetlands areas so no net loss of
wetlands would occur, thus meeting 10 CFR 1022 and 40 CFR 6 (Appendix A).
Cost Effectiveness
The remedy covering the K-1407-B/C Ponds will remain in place for long-term control
of radioactive and chemical contaminants. The use of rock in the K-1407-B Pond and soil in the
K-1407-C Pond as fill material will provide control of exposure and contaminant migration by
using a technology that is cost-effective in comparison to other technologies and techniques
proposed in the remaining alternatives.
The $4.5 million cost estimate for Alternative 2 represents the most cost-effective action
alternative evaluated. Alternative 3 is not as well suited for the K-1407-B Pond, where the rock
fill is needed to facilitate construction activities and reduce the potential for cross-media impact.
Alternatives 3,4, and 5 offer reduction in infiltration of surface water compared to Alternative 2;
however, there is little significant migration of contaminants in the groundwater at the site from
the pond soils. A decrease in surface water infiltration would be of little advantage at the
K-1407-B Pond where most of the contaminants are below the water table. Because the potential
for leaching of contaminants from the pond soils is limited, there is no appreciable advantage to
D9302I5.4PS51 2-94 09/24/93
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Table 2.20. ARARs and TBCs for the K-1407-B/C Ponds Alternative 2
Actions Requirements Prerequisites
Chemical-specific None None
Location-specific9
Within floodplain areas Actions must be taken to reduce the risk of flood Agency action that involves:
Federal citation
None
40 CFR 6.302(b);
Tennessee Code
Annotated
None
N>
Action-specific
On-site construction/
excavation
Surface water control
loss, minimize the impact of floods on human
safety, health, and welfare, and restore and
preserve the natural and beneficial values of
floodplains
Agencies must evaluate potential effects of actions
in floodplains and ensure consideration of flood
hazards and floodplain management. If action is
taken in floodplains, the Agency shall consider
alternatives to avoid adverse effects and
incompatible development and minimize potential
harm
Must take reasonable precautions to prevent
paniculate matter from becoming airborne
Fugitive dust may not be emitted as visible
emissions beyond property boundary lines for
more than 5 min/h or 20 min/day
Monitor surface waters to ensure compliance with
state water quality standards
Consultation with TDEC is required to ensure
compliance with the substantive requirements of
the permitting process
Implementation of good site planning and best
management practices to control storm water
discharges
- providing federally undertaken,
financed, or assisted construction
and improvements
- conducting federal activities and
programs affecting land use
- applicable
40 CFR 6
(Appendix A);
10 CFR 1022
Handling or transporting any materials
- applicable
Handling or transporting any materials
- applicable
Wastes discharged into adjacent
streams or other surface waters
- applicable
Stormwater discharges associated with
construction activity at industrial sites
involving disturbance of 5 acres total
land - relevant and appropriate
40 CFR 122
1200-3-8-.01
I
1200-3-8-.01
1200^-3
1200-4-10-.05
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Ibble 2.20 (continued)
Actions
Clean closure
Requirements
No post-closure monitoring or post-closure care
required
Prerequisites
Removal or decontamination of all
waste residues and contaminated
Federal citation
40CFR
265.228(a)(l)
Tennessee Code
Annotated
1200-1-1 l-.05(ll)(g-l)
Residual radioactivity
o\
Consultation with TDEC is required to ensure
compliance with the substantive requirements of
the permitting process
Public exposures from all sources must not exceed
an effective dose equivalent of 100 mrem/year
All releases of radioactive material shall be
ALARA
Authorized limits are levels of residual radioactive
material that shall not be exceeded if the remedial
action is to be considered completed and the
property is to be released without restrictions on
use
subsoils at interim status surface
impoundments - applicable
Storm water discharges associated with 40 CFR 122
industrial activity - applicable
Management of residual radioactive
material left in place - TBC
DOE Order"
5400.5(IV.3a)
DOE Order
5400.5(IV.2a)
DOE Order
5820.2A(HI.3j)
DOE Order
5400.5(IV.2d)
DOE Order
5820.2A(III.3j)
1200-4-10-.04
ALARA = as low as reasonably achievable
ARAR = applicable or relevant and appropriate requirement
TDEC = Tennessee Department of Environment and Conservation
TBC = to be considered
USACE = U.S. Army Corps of Engineers
'The wetlands survey conducted for the site indicated thai there are no wetlands areas present at the K-1407-B/C Ponds, and concurrence with this finding is expected
from the USACE. However, if wetlands were determined to be present at the site, then ARARs pertaining to wetlands would be met.
bDOE orders, while not ARARs, are treated as TBC guidance and/or criteria.
-------
be gained by the added cost of these alternatives. Alternative 6 would remove all residual
contaminants from the site, but its implementation would create health and financial liabilities
associated with the removal, handling, and long-term maintenance of the waste and would
represent a significant increase in cost.
The increased costs of Alternatives 3 through 6 compared to Alternative 2 do not correlate
to a commensurate increase in protection, permanence, effectiveness, or other advantages to
justify the increase in cost. The safeguards provided by Alternative 2 comply with available
guidelines to protect human health and the environment in a cost-effective manner.
Use of Permanent Solutions and Treatment Technologies
Alternative 2 provides a solution to existing and potential threats posed by contaminants
in the K-1407-B/C Pond soils. All exposure pathways to contaminants in the pond soils and the
associated risks will be effectively eliminated by the implementation of the remedy. Although
residual contamination will remain in place at the site, it will not pose a risk to human health and
the environment because of the isolation of contaminants and the shielding of exposure to direct
ionizing radiation. The implementation of Alternative 2 will make it virtually impossible to
reestablish baseline conditions at the site in the future in an attempt of establishing residency.
Therefore, the remedy has a high degree of effectiveness even for the most conservative risk
scenario, the hypothetical on-site resident.
Alternative 2 does not address groundwater contamination at the site; groundwater
contamination will be addressed under the K-25 OU Groundwater RI/FS. However, the potential
for contaminant mobility by leaching and migration of contaminants from pond soils into
groundwater at the site is very limited, and there is currently no risk posed to human health or
the environment by groundwater exposure pathways. Remediation will reduce the mobility of
soil contaminants by eliminating transport by air or surface water. The toxicity of residual soil
contamination will not be reduced, but risk will be reduced by eliminating all existing exposure
pathways. Alternative 6 would remove all contaminants from the site but would result in risks
associated with removal, handling, and long-term storage of waste by-products.
Because there is no effective treatment for residual radiological contamination such as
found in the pond soils, Alternative 6 would not reduce the toxicity; instead, the volume of waste
would be significantly increased. Although mobility might potentially be decreased, the waste
by-product from excavation and treatment would be above ground, and any failure in long-term
management could result in an eventual increase of contamination migration. Because of the
considerable technical and logistical problems associated with removal and treatment and because
of the considerable cost, this alternative is not viable.
D930215.4PS3I 2-97 09/24/93
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Alternative 2 utilizes permanent solutions and treatment technologies to the maximum
extent practicable. Because treatment of the principal threats at the site is not practicable,
management of in situ residues is a more appropriate remedy at this site. Furthermore, this
remedy is easily implemented, cost-effective, and presents no short-term unacceptable risks to
human health or the environment. Based on its advantages and cost effectiveness, Alternative 2
represents the best balance of trade-offs for remediation of the K-1407-B/C Ponds.
Preference for Treatment as a Principal Element
The principal threats to human health and the environment to current and potential
receptors at the K-1407-B/C Ponds site are posed by residual metals and radiological
contamination in the pond soils and by contaminants in groundwater. All visible traces of sludge
(the original contaminant source at the site) and associated soil were removed under RCRA
closure activities conducted between 1987 and 1989. The contamination remaining in the pond
soils represents residual contamination that migrated from the sludges into underlying soil prior
to sludge removal.
Because treatment of the principal threats at the site is not practicable, this remedy does
not satisfy the statutory preference for treatment as a principal element. Current technology does
not offer means to effectively treat residual radiological contamination such as that found at the
K-1407-B/C Ponds site. Therefore, management of in situ residues is a more appropriate remedy
at this site.
The implementation of the selected remedy will effectively eliminate all current and
potential exposure pathways and associated risks at the site except for groundwater pathways;
groundwater will be remediated under the K-25 Groundwater OU. However, because residual
contamination will remain on-site, institutional controls, reopeners, and contingencies to ensure
the remedy remains effective, to be agreed upon with the state, will be implemented. For
example, under DOE Order 5400.5 the selected remedy is considered a restricted closure.
Therefore, if in the future unconditional release of the site becomes a possibility, DOE (or its
successor) shall conduct a review of the remedy and current site conditions prior to transfer of
the K-25 Site from DOE (or its successor) to another person or entity, and any property transfer
will follow the procedure outlined in the FFA (DOE 1992d), Sect. XLIII, Property Transfer.
Additionally, because this remedy will result in hazardous substances remaining on-site
above health-based levels, a review will be conducted every 5 years, beginning within 5 years
after commencement of the remedial action, to ensure that the remedy continues to provide
adequate protection of human health and the environment in accordance with CERCLA 121(c).
This review will be augmented by data available from post-remediation groundwater monitoring
at the site.
D93021S 4PS5I 2-98 09/24/93
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EXPLANATION OF SIGNIFICANT CHANGES
The Proposed Plan for the K-1407-B/C Ponds (DOE 1992c) was released for public
comment in February 1993. It identified Alternative 2, Engineered Rock Fill, as the K-1407-B/C
Ponds preferred alternative. No written or verbal comments were submitted during the public
comment period. Accordingly, it was determined that no significant changes to the remedy, as
it was originally identified in the Proposed Plan, were necessary.
D9302I5.4PS5I 2-99 09/24/93
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PART 3. RESPONSIVENESS SUMMARY
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COMMUNITY PREFERENCES
The Proposed Plan for the K-1407-B/C Ponds (DOE 1992c) remedial action was released
to the public on February 3, 1993. The remedial action described in the Proposed Plan is
intended to reduce the potential threats to human health and the environment posed by the
radiological and chemical hazards associated with the contaminated soils remaining in the
K-1407-B Holding Pond and the K-1407-C Retention Basin, and to prevent the spread of
contamination. The major component of the remedial action is isolation and shielding provide
by filling the ponds.
No comments were received during the public comment period. Based on the absence
of public comment, it is assumed that the public is in favor of the proposed solution.
Accordingly, the preferred alternative has been selected for remedial action at the K-1407-B/C
Ponds as presented in the Proposed Plan.
INTEGRATION OF COMMENTS
The Proposed Plan for the K-1407-B/C Ponds (DOE 1992c) remedial action was released
to the public in February 1993 by inclusion in the Administrative Record maintained at the IRC
in Oak Ridge, Tennessee. The Notice of Availability of the Proposed Plan was published in the
Oak Ridger on February 2, 1993; in the Knoxville News Sentinel on January 31, 1993; and in the
Roane County News on February 2, 1993. A public comment period was held from February
3 through March 4, 1993. The opportunity for a public meeting was offered in the Notice of
Availability published in the newspapers. No comments were received from the public.
The public at large has been involved in the general environmental restoration of DOE's
facilities on the ORR through various activities on many occasions. The contamination of the
K-1407-B/C Ponds has raised little interest in the community at large because of the isolated
location and restricted access to this area.
Summary of Comments Received and Agency Responses
No public comments were received during the public comment period.
Remaining Concerns
At the end of the public comment period, no other concerns had been raised by the
community.
D9302IS.4PSSI 3-3 09/24/93
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PART 4. REFERENCES
-------
REFERENCES
Ashwood, T. L. et al. 1986. Sediment Contamination in Streams Surrounding the Oak Ridge
Gaseous Diffusion Plant, ORNL/TM-9791, Publication No. 2597, Environmental Sciences
Division, May.
Baes, C. E, III, et al. 1984. A Renew and Analysis of Parameters for Assessing Transport of
Environmentally Released Radionuclides through Agriculture, ORNL-5786, Oak Ridge
National Laboratory, Martin Marietta Energy Systems, Inc., Oak Ridge, Tenn.,
September.
DOE (U.S. Department of Energy) 1992a. Remedial Investigation/Feasibility Study for the
K-1407-B/C Ponds K-25 Site, Oak Ridge, Tennessee, DOE/OR-1012&D3, December.
DOE 1992b. Minutes from the June 16, 1992, DOE Technical Vtorking Group Meeting,
K-1407-B/C Ponds, U.S. Department of Energy, Oak Ridge, Term., July 8.
DOE 1992c. Proposed Plan for the K-1407 B/C Ponds, K-25 Site, Oak Ridge, Tennessee,
DOE/OR-1013&D3, December.
DOE 1992d. Federal Facility Agreement for the Oak Ridge Reservation, DOE/OR-1014,
January 1.
Energy Systems (Martin Marietta Energy Systems, Inc.) 1989. RCRA Facility Investigation Plan
General Document, Oak Ridge, Tennessee, K/HS-132 Rev. 1.
Energy Systems 1990. K-25 Plant Site Waste Area Grouping Strategy Document, Oak Ridge,
Tennessee, K/ER-22, Oak Ridge, Tenn., February.
Energy Systems 1993. Surveillance and Maintenance Plan for Inactive ER Remedial Action Sites
at the Oak Ridge K-25 Site, Oak Ridge, Tennessee, K/ER-54, Oak Ridge, Term., January.
EPA (U.S. Environmental Protection Agency) 1988a. Superfund Exposure Assessment Manual,
EPA/540/1-88-001, U.S. Environmental Protection Agency, Office of Emergency and
Remedial Response, April.
EPA 1988b. Guidance for Conducting Remedial Investigations and Feasibility Studies Under
CERCLA, Interim Final, EPA/540/G-89/004, U.S. Environmental Protection Agency,
Office of Emergency and Remedial Response, October.
EPA 1989a. Risk Assessment Guidance for Superfund, \blume I: Human Health Evaluation
Manual, U.S. Environmental Protection Agency, Office of Emergency and Remedial
Response, September.
D930215.4PS51 4-3 . 09/24/93
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EPA 1989b. Risk Assessment Guidance for Superfund, \blumel: Human Health Evaluation
Manual (Pt. A), Interim Final, EPA/540/1-89-002, U.S. Environmental Protection
Agency, December.
EPA 1989c. Remedial Facility Investigation Guidance \blumel, EPA/530/SW-89-031, May.
EPA 1989d. Human Health Evaluation Manual, EPA/600/8-89/043, U.S. Environmental
Protection Agency, Office of Health and Environmental Assessment, August.
Fbrstrom, J. M. 1990. Groundwater Contamination in the Vicinity of the K-1407-B and C
Ponds and Implications for Closure, Briefing Book, K/ER/Sub-90/01090/1, PAI
Corporation, June.
Geraghty & Miller, Inc. 1989a. Ground-Witer Quality at the Oak Ridge Gaseous Diffusion
Plant, Final Report, K/SUB/85-22224/11, October.
Geraghty & Miller, Inc. 1989b. Hydrogeology of the Oak Ridge Gaseous Diffusion Plant,
Revised Final Report, K/SUB/85-22224/12, December.
Haymore, J. L. et al. 1988. K-1407-B and K-1407-C Surface Impoundment False-Positive
Groundwater Assessment, K/HS-214, Martin Marietta Energy Systems, Oak Ridge
Gaseous Diffusion Plant, May.
Lee, S.Y. et al. 1988, Soil and Surficial Geology Guidebook to the Oak Ridge Reservation,
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