Proposed Plan for the ORNL Waste Area Grouping 13 Interim Remedial Action

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U.S. Department of Energy Field Office Oak Ridge, Tennessee 120 South Jefferson Circle Oak Ridge, Tennessee 37830

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3. THE SCOPE AND ROLE OF THE INTERIM REMEDIAL ACTION ............... 5 4.1 CONTAMINANTS OF CONCERN .................................. 5 5.1 ALTERNATIVE 1. NO ACTION ..................................... 7 5.3 ALTERNATIVE 3. EXCAVATION AND STORAGE AT A CURRENTLY OPERATING WASTE MANAGEMENT FACILITY ........................ 5.4 ALTERNATIVE 4. EXCAVATION AND DISPOSAL AT SWSA 6 .............. 11 6. EVALUATION OF ALTERNATIVES ...................................... 13 6.2 EVALUATION OF ALTERNATIVES .................................. 14 6.21 Overall Protection of Human Health and the Environment ......... 14 6.2.3 Long-Term Effectiveness and Permanence ..................... 14 6.2.8 Regulatory Agency Acceptance ............................. 16 6.2.10 Interactive or Cumulative Effects Wth Other DOE Field Office

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Estimated cost of Alternative 2 9 Estimated cost of Alternative 3 11 Estimated cost of Alternative 4 13 Summary of contaminants at WAG 13 and WAG 6 ....................... Summary of CERCIA criteria ....................................... Location of the WAG 13 cesium plots on the DOE Oak Ridge Resenration ..... WAG 13 site map showing the location of the cesium plots ................ Location of the WAG 13 cesium plot shields under Alternative 2 ............. Location of the Interim Waste Management Facility (MIMF) ................. Location of the Solid Waste Storage Area (SWSA) 6 fill area ................

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ACRONYMS AND INITWSMS as low as reasonably achievable applicable or relevant and appropriate requirements Comprehensive Environmental Response, Compensation, and Liability Act Code of Federal Regulations U.S. Department of Energy U.S. Department of Transportation U.S. Environmental Protection Agency Federal Facilities Agreement Hazardous and Solid Waste Amendments (of 1984) Interim Remedial Measures Study Interim Record of Decision Interim Waste Management Facility National Environmental Policy Act National Priorities List operation and maintenance Oak Ridge National Laboratory Oak Ridge Resenration Resource Conservation and Recovery Act reasonable maximum exposure Tennessee State Route 95 Solid Waste Storage Area Tennessee Department of Environment and Consenration Waste Area Grouping

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This Proposed Plan describes the problems assodated with Waste Area Grouping (WAG) 13 and the interim remedial action being corrsidered for the cesiumantaminated plots there. The goal of the interim action is to reduce or remove the threat to human health and the environment posed by the elevated levels of gamma radiation from the cesium plots The remaining area of WAQ 13 (outside the plot boundaries) will be addressed in future remedial actions The WAG 13 cesium plots are located in an of the Clinch River at mile 20.5 and 1.3 miles sou!h of the intersection of Bethel Valley Road and Tennessee State Route 95 (SR 95) (Fig. 1). The eight treatment plots were used for a simulated nuclear weapons fallout study undertakenby the Oak Ridge National Laboratory (ORNL) in 1968. ORNL is part of the federally owned Oak Ridge Reservation (ORR), operated for the U.S. Department of Energy (DOE) by Martin Marietta Energy In August 1968, four of the treatment plots with cesium-137; the remaining four plots were used as uncontaminated controls (Fig. 2). The gamma radiationexposure rate at the fence line surrounding the plots has been measured at 40 to 150 pWh (Yakintas forthe WAG 13 cesium plots was performed to determine the best alternativefor reducing the health threat posed by the elevated performed to determine the potential effects of proposed interim actions. In compliance with the National Environmental Policy Act (NEPA), a categorical exclusion is being issued that states the Proposed Interim Action will have no adverse impact on the environment This Proposed Plan highlights key information found in the IRMS for the WAQ 13 cesium plats and related Investigation reports; these are available to the public at the Information Resource Center in Oak Ridge, Tennessee. The purpose of this Proposed Plan is to describe the site and its conditions, provide a brief anatysis of the interim action alternatives being considered, and identify the preferred interim action alternative presented in the IRMS. This Proposed Plan, developed by DOE, the lead agency respwsiblefor remediation of the ORR, also provides information on how the public and interested parties can participate in the decii-making process. The US. the Tennessee De- of Environment and Consenration (lDEC) are the oversight agencies. In consultation with these agencies, DOE will select the interim remedii action for the WAG 13 cesium plots only after reviewing and considering the puMc comments on this Proposed Plan and other supporting documentation Public comments are an important part of the interim action alternative selection

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Location of the WAG 13 cesium plots on the DOE Ook Ridge

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Environmental Restoration Program WAG 13 site map showin location of the cesium $:e

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Plan for public comment as part of its public participation responsibiliiies under Sect to the site; this has since decayed to approximately 5.1 Ci as of June 1992 117(a) d the Comprehensive Environmental Response, Compensation, and Liability Ad infomation or public comments, DOE may modify the preferred Interim remedial action or select another alternative. Therefore, the public is encouragedto review and comment on all d the described alternatives and any other alternatives that might be appropriate for krterim remedial action at the WAG 13 Field activiiies associated with the interim action will be Initiated within 15 mocnhs d signing d the Interim Record of Decision (IROO). Completion of the interim action is subject to fiscal constraints and will be part d the Federal Facilities Agreement (FFA) The approximately Sacre site is enclosed by a fence and contains eight treatment plots. Each plot is 33 by 33 ft and is enclosed in sheet metal extending 18 in. below the surface and 24 in. above grade. As part of a weapons fallout experiment in 1968, four of the eight plots were contaminated with Cesium-137, which was fused to silica sand particles ranging from 88 to I77pm in size. The sand particles were spread evenly ovw the plots at a concentration dMgld. Each d the four contaminatedplots received control plots received none (Yalcintas et ai. 1988). Hence, a total of 8.8 Ci was applied Between June 1987 and March 1988, the ORNL Measurement Applications and Development Group conducted a surface redi ical investigation (Yalcintas et al. 1988). Outside the fenced area, gamma radiation exposure rates were measured at 23 points on the Clinch River and 9 points along the riverbank. Readings were also taken inside the fenced area The report concluded that the maximum exposure to the public would be approximately 19 pR/h along the shoreline closest to the cesium137 plots and up to 150 pWh at the fence. Gamma ray exposure rates measured at selected plot boundary locations within this fenced area ranged from 1.3 to 35 mFUh Subsequent field investigations were conducted in support of the IRMS to determine the vertical extent of cesium-137 contamination within each cesium plot. These studies were used to support the On November 21,1989, €PA issued a final rule listing the ORR for inclusion on the National Priorities List (NPL). inclusion on WAG 13 comply with the regulatory requirements of CERCIA. CERCIA, as and Reauthorization Act of 1988, sets the requirements for an NPL site. Additionally, the ORR is operating in compliance with the Reswrce Conservation and Recovery Act (RCRA) of 1976 and the Hazardous and Wid Waste Amendments (HSWA) of 1984. amended by the supelfund Amendments

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TDEC enforces compliance with RCRA and HSWA The WAG 13 cesium plots were lied in the RCWHSWA Permit issued on Sepmber 26, 1986, and amended in Also, the NationalContingencyPlan requires federal faciliies on the NPL to enter into an FFA with EPA and the appropriate state government agency. Accordingly, an FFA among DOE, EPA, and TDEC became effectbe on January 1,1992. Asa result of the FFA, environmental restoration activities and remediation schedules for the various environmental restoration projects on the the FFA, the WA(3 13 cesium plat site was determined to be a candiiate for an interim remedial action. An approved IROD is scheduled for the site by September 30, 1992 For the WAG 13 cesium plats, the process leading to an IROD includes conducting an assessment of the site and current available information; performing an IRMS to analyze and compare remedial alternatives; and obtaining approval of the IROO following DOE, EPA, TDEC, and public review d the Proposed Plan The goal of the interim remedialaction at the WAG 13 cesium plots is to reduce the risk to humanhealth resultingfrom current elevated levels of gamma radiiion on the WAO and at weas accessible to the public along the To achieve this goal, only the cesiumcontaminatedsoil within the sheet metal pkA endosures will be addressed The preferred alternative is to excavate the contaminated soils and place them in the Sdid Waste Storage Area (SWSA) 6 fill area in WAG 6. Following approval of an IROD for the cesium plats, several other documents will be prepared as required - a Remedial Design Work Plan, a Remedial Design Report, a Remedial Action Work Plan, or a Post Construction Repon After the cesium plots are addressed, several other activities may take place. A final investigation of WAO 13 would take place in the future, resultingin more remedial actions or a decision to take no further actions. The exact schedule for future actions is unknown, but the schedule will depend on risk to the public, budgetary constraints, and regulatory agency input. 4.1 CONTAMINANTS OF CONCERN In the preliminary human health risk assessment,cesium137fused to silica sand particles was determined to be the only contaminant d concern a! the WAG 13 The exposure scenarios examined in the preliminary human health risk assessment were (1) the worker who mows the area, (2) a fishermanboater on the Clinch River who comes within 150 R of the cesium plots, and (3) an individualat the fence line who comes within 25 R of the cesium plots. Determinatim of current exposures was performed assuming that no remediation activities are implemented and that the site is fenced and inactive. External exposure to Ming radiation poses the majority of risk to the exposed populations and was

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determined to be the dominant pathway d concern for all three scenarios. Lifetime cancer risks associated with the WAG 13 cesium plats were calculated for (1) for the worker mawing around the plots, (2) fishermanlboater on the Clinch River, and (3) maKimurn exposure for an individual at the fence line. RME assumptions for the preliminary health risk assessment were adopted from ORNL's Radiation Exposure The RME 8c8naT/o for the worker assumes thad an individual spends 25 wear On-Site for 25 years and is exposed to an average gamma rate d 150 pFUh measured on-site. The RME scenario for the fisherman/boater assumes that an individualspends 52 wear (1 Week) for 30 years on the Clinch River near the WAG13 cesium plots and is exposed to a maximum gamma rate d 19 pR/h measured on the Clinch River. The maximum exposure scenario at the fence line assumes that an individualspends 8760 wear (24 Wday for 365 days) for 30 years at the fence line and is exposed to a maximum gamma rate d 3.4mR/h measured at the fence line. The effective dose equivalent for the worker, the fbheman, and the individual at the fence line was estimatedto be 1.5 rem, 0.021 rem, The risk to the workerwas estimated to be 1 x loJ (I in 1000 chances d developing the Clinch River was estimated to be 2 x lod, and risk to an individual at the fence was calculated to be 2 x w. Calculated risks frm lifetime exposure to radionuclidesand chemicals were compared W. ~ n yrisk vatues greater than 1 x 104 (1 in 10,OOO chances of developing cancer) are unacceptable, and any risk values less developing cancer) are acceptable by EPA to €PA'S target risk range of 1 x lod to 1 x Acceptance Os risks between 1 x 1 P and 1 (Le., population exposure). The calculated risks are in addition to the average risk to the U.S. population d 1.4 x 1@ resulting from naturally occurring background The risk to the fishemadboater falls within EPAs acceptable risk range. Although exposure to the worker is within DOE guidelines, risks to the worker mowing around the cesium plots and to the individual at the fence line exceed EPAs target risk range. Ecologicalrisk to the anknal population and vegetation growing on and around the cesium plots is considerednegligible. Vial inspection of the plants growing on the plots and the wildlife in the area showed no If no interim remedial action Is taken, actual or threatened releases d hazardow substances from the WAG 13 cesium plots may present a current or potential threat to public health, wetfare, or the environment.

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The interim actionalternativesfor addressing the gamma radiation exposure from the WAO 13 cesium plots are as follow: Alternative 1, no action; storage at a currently operating waste management facility; and Alternative 4, excavation and disposal at SWSA 6. These alternatives are not intended to remediate the entire problem at WAG 13. The action discussed and recommended in this report is an interim remedial action intended to reduce further degradation of the environment resulting from elevated gamma radiation exposures. CERCIA requires that the no-action alternative be evaluated to serve as the baselinefor comparison at every sire. Under this alternative, no further action would be taken to reduce the risk to human receptors from the current elevated levels d gamma radiiion on the WAG and along the perimeter fence that is accessible to the Alternative 1 does not meet limits and consideratiocls set forth by EPA and DOE orders for exposure of the public and workers to radiation caused by a DOE faciiii. Also, DOE is responsible for ensuring that all DOE activities are operated in such a way. that radiatii doses to Widuals will be as low as reasonably implemented immediately and would cost Shielding involves placing reinforced concrete boxes over each cesium plot. The boxes are designed to deflect and contain the gamma radiation within the bo& Fig. 3 shows the shield locations. After shield installation, gamma radiation exposure rates are reducedto backgroundlevels (9pR/h) at the boundary fence, thus reducing risk to the general public on or near the Clinch River. Background levels are average radiation levels expected at the ORR reducing the level of gamma radiation to background levels, the shields would reduce rainwater infiltration into the plots, thereby reducing to some extent potential contaminant transport caused by rainwater percolation to the groundwater. A limitation to this alternative is the possibiii of shield failure or removal. Postremediation risk levels for the worker (inside the fence) would be eliminated. However, the potential exists for future releases of gamma radiation if the shields should fail. After shield installation, periodic monitoring and maintenance will be required to ensure the technical integrity d the concrete lhiiattemativecomplieswith DOE ordersfor exposure d the puMi and workers to radiation. Facilities are required by 40 Code designed to contain contaminated soil and

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prevent washout by a 100-year flood (1 in 100 chances of being equaled or exceeded in a given year). Portions of two shields will be located within the 100-year floodplain (750.4 R elevation). The resulting environmental impact d the ConStNction advitbs will be insignificant because construction will …