Interim Record of Decision for Oak Ridge National Laboratory Waste Area Grouping 13, Cesium Plots, Oak Ridge, Tennessee

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Interim Record of Decision for Oak Ridge National LPborPtory Waste Area Grouping 13 Oak Ridge, Tennessee U.S. Department of Energy m c e of Environmental Restoration and Waste Management 120 South Jefferson Circle Oak Ridge, Tennessee 37830 under Contract No. DE-AC05-MOR2 1851

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TABLE OF CONTENTS STATEMENT OF BASIS AND PURPOSE ..................... ASSESSMENT OF 7HE SITE .............................DESCRIPTlON OF SELECTED REMEDY .................... 1-2 PART 2. DECISION SUMMARY ................................ 2-1 SITE NAME. LOCATION. AND DESC mON SITE HISTORY AND ENFORCEMENT ACTIVITIES ............. 2-2 SCOPE AND ROLE OF THE RESPONSE ACTION ............... 2-5 SUMMARY OF SITE CHARACTERISTICS .................... 2-6 SUMMARY OF SITE RISKS ............................. 2-6 Waste Management Facility ......................... 2-8 Overall Protection of Human Hcalth urd the Environment ........ 2-10 Reduction of Toxicity. Mobility. or Volume Through Treatment .... 2-10 Reguluory Agency Acceptance ......................... 2-12 Protection of Human Health md the Environment ............. 2-13 Alternative 3-Excavation and Storage at a Currently Operating Alternative 4-Excavation and Disposal at the WAG 6 Inw-Level SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES ....

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TABLE OF CONTENTS (continued) Use of Permanent Solutions and Alternative Treatment Reference for Treatment ............................ 2-15 EXPLANATION OF SIGNIFICANT CHANGES ................. 2-16 PART 3. RESPONSIVENESS SUMMARY ........................... 3-1 Summary of Comments Received and Agency Responses ......... 3-2 Background on Community Involvement ................... Appendix A . MEETING MINUTES AND LETTER OF RESPONSE

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as tow as reasonably achievable rpplicable or relevant and appropriate requirement Comprthensive Environmental Response, Codon, and Liability Acf Code of Fdud Regulations U.S. Dep ment of Energy U.S. Environmental Protection Agency bibi lit y study Interim Record of Decision Oak Ridge National Laboratory Oak Ridge Reservation picocuries per gram reasonable maximum exposure Tennesste State Route to be considered Tennessee Code Annotated Tennessee Department of Environment and Conservation Waste Area Grouping

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SITE NAME AND LOCATION Waste Area Grouping (WAG) 13 Oak Ridge Reservation (ORR) oplt Ridge, Tennessee STATEMENT OF BASIS AND puRposE 'Ibis decision document presents the selected interim remedial d o n for b e ORNL WAG 13 in Oak Ridge, Tennessee. This action was chosen h amrdance with the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980, 8s amended by the Superfund Amendments and Reauthorization Act of 1986, urd, to the extent practicable, the National Oil and Hazardous Substances Pollution Contingency Plan. This decision is based on the administrative record file for this site. The State of Tennessee and the U.S.Environmental Protection Agency @PA) concur with this interim action for the WAG 13 remediation. Actual or threatened releases of hazardous substances from this rite, if aot addressed by implementing the response action selected in this Interim Record of Decision (TROD),may present a current or potential threat to public health, welfare, or the environment. DESCRIPTION OF SELECTP) REMEDY T h e purpose of this interim action is to reduce tbe risk to buman b d t h urd the environment resulting from current elevated levels of gamma radiation on the rite urd at areas accessible to the public and adjacent to the rite. To achieve this, only the cesiumantaminated mil within the plot will be addressed. 'Ibb i s not the final action planned for WAG 13. Subsequent actions are planned to fully address the remaining threats posed by tbc conditions at b e rite. h dated in CERCU, the site will be evduated during the Remedial Investigation

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The major components of the interim action remedy are the following: excavate ctsiumcontamtnat* ed soil until residual contamhtion is containerize the excavated soil in steel boxes designed for the storage of transport the excavated soil to WAG 6 low-level waste silos by truck; aal line each excavated plot with a permeable liner aal backfill with 8 clean compacted fill material md a topsoil layer. Interim remedial action on WAG 13 prior to completion of the RIlFS will provide additional benefits consistent with the goals of CERCLA, including: preventing a known source of cesiumcontaminated sediment from producing elevated levels of gamma radiation on WAG 13 and to areas accessible to the reducing further degradation to the environment by dimbating the source of reducing the difficulty and risk associated with future surveillance, maintenance, and remedial activities on WAG 13. This interim action protects human health and the environment, complies with federal and state applicable or relevant and appropriate requirements (ARARS)for this limited-scope action, and is cost-effective. This action is interim and is not intended to use permanent solutions and alternative treatment (or resource recovery) technologies to the maximum extent practicable, given the limited scope of the action. Again, this action is not a final remedy for the WAG. Therefore, the statutory preference for remedies that employ treatment that reduces toxicity, mobility, or volume as a principal element will be addressed at the time of the final response action. Subsequent actions are plkned to fully address the remaining threats posed by the site. Because this is an ROD, review of this WAG and of this remedy will be continuing as part of the development of the final remedy for the site.

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Oak Ridge Field Office Director, DOE Oversight Division State of Tennessee Tennessee Depamnent of Environment and Conservation U.S. Environmental Protection Agency, Region IV

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SITE NAME, LOCATION, AND DESCRIPTION WAG 13 it part of ORNL on the ORR CERCLA Site in Rome County, Tamessee. ORNL k part of the federally owned ORR, managed for DOE by Mpnin Muim Energy Systems, b c . The WAG 13 cesium plots are in an approximately &acre grassy field 330 ft north of the Clinch River at mile 20.5 rad 1.3 miles south of the iatersectjon of &thd Valley Road T h e WAG 13 cesium plots u e enclosed by a perimeter furce rpproximorely loo0 ft by fk. There K e eight treatmeat plots that were used for 8 rimulatOd nuclear weapons fdlout cmdy undertaken by ORNL. Ea& plot is 33 by 33 ft md i s faced with chat mdtpl extending 18 in. below the surface md 24 in. above surface. Tbere are no other ~tructureson the site. T h e elevated gamma radiation levels emitted from these plots pose a potentia threat to human health SITE HISTORY AND ENFORCEMENT ACTIVITIES b August 1968, to simulate conditions of a nuclear fallout, four of the trutment plots (Nos. 2,4,6, and 7) were contaminated (seeded) with '"Cs; the remaining four plots were used lis uncontaminated controls (Fig. 2). T h e seeding was achieved by spreading lmCs-hed sand particles evenly over the plots at 72 g/m2. Each test plot received 2.2 Ci of "'0,while the control plots rdved none. A surface radiological investigation was conducted at and around the rite between June 1987 md March 1988 by ORNL's Measurement and Development Group (Yalcintiis a d. 1988). Outside the fenced area, radiation levels were measured at 23 loutions on the Clinch River and 9ldons dong the riverbulk. Radiationlevds were also masur d inside the fencad urn. The ~ummpryof rite characteristics section in this IROD provides more deiails regarding radiation On December 21, 1989, the ORR was placed on CERCLA'r National Priorities List, whicb mandates specific requirementsthat environmental restoration activities must follow. DOE must Ifso operate in compliance with the National Envuonmental Policy Act. An Interim Remedid Mwures Study (Radian July 1992) for the WAG 13 cesium plots was completed in July 1992 to determine the best alternative for reducing the bealth threat posed by the gamma radiation in the plots.

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Locdion dUu WAO IS cdum plolr on ut4 DOE am. fnvironmonhl Rmtorrtion Prooram Fia. 1

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HIGHLlGHTS OF COMMUNITY PARTICIPATION The Proposed Plan for tbe ORNL WAG 13 Interim Remedial Action was r t l d to the public in July 1992. ' b e Proposed Plan was made available to the public iP &e admhhtrative mrd maintained 1 the Info don Resource Center in Oak Ridge, T-e. Notice of mailability for the Proposed Plan was published in the O d Ridgcr on July 10.12, ad 15* 1992; iu tbe KMNsllc hkws-sentinel on July 10, 12, md 15, 1992; rad in tbe ROMC Cwnry Mvs on July 13, 15* md 17,1992. A public comment period was held from July 14 to August 12,1992. A public meeting was not scheduled, but opportunity for a meeting was offerad in the published notice of mailability. A response to tbe comments received during the comment period is included in the Responsiveness Summary, which is Part 3 of this IROD. This decision document presents the rJectd interim remedial action for the ORNL W A G 13 cesium plots. This selection was made in accordance with CERCLA, as mended by the Superfund Amendments ud Rauthorization Act of 1986, rad to the extent feasible, the National Contingency Plan. SCOPE AND ROLE OF THE RESPONSE ACTION The goal of this response action is to reduce the risk to hum hd th ud the environment resulting from the current elevated levels of gamma radiation on WAG 13. During this interim action, only the cesiumcontaminated roil within the plots will be addressed. Excavating these 103s md placing them in WAG 6 low-levelwaste silos will prevent a known source of cesiumcontaminated sediment fiom producing devoted levels of gamma radiation on WAG 13. Subsequent actions under CERCLA are planned to fully address the threats posed by the remaining exposure pathways at the site. 'Ibese m y include, but are not limited to, the moil outside the plot boundaries, the roil beneath the depth of excavations mmplaed during the bt~haction, p~ndwi~t~r,md surface water. Tbe remaining UCIS of tbe site will be evdumed during the RIffS, IS mandated in CERCLA. This interim remedial raion i s consistent with planned fume activities at tbe rite. In PartiahrD this interim action will provide a duction in tbe difficulty and risk rssociated with future surveillance, maintenance, tnd remedial mivitis.

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SUMMARY OF SITE CHARACTERlSIlCS Contambation on WAG 13 has resulted solely from the inrrntinnll deposition of mCs fir tbe purpose of gaining hwwledge of the effects of wclw frllout. A mud of 8.8 Ci was r p r e o d ovm the four test plots rad has decayed to 5.1 Ci as of lube 1992. 'Ibe ullfice radiological investigation conducted at the rite concluded that the maximum exposure to tbe public would be approximately 0.019 mwh dong tbe rbotah dorcst to the plots rad up to 0.150 mR/b at the perimeter fence. Gamma ray ejrpouue ram measured It plot plot boundaries within the fenced area ranged from 1.3 to 35 mwh (Ydcintas # d. 1988). Soil samples taken within the plots indicate that the lnCs has been detected above 1 pCi/g (daection limit) at depths up to 3 ft. SUMMARY OF SITE RISKS A preliminary health risk assessment study was conducted for WAG 13 urd the only contaminant of concern was determined to be '"Cs (Radian July 1992). Cesium-137 is a beta miner (512 KeV) that also releases gamma at 661 KeV and has I 3 0 - y ~half-life. Although 1987 soil samples from two locations between the contaminated plots rad the nearby creek bed &ow that contamination bas migrated (OWL 1988), the scope of this action is limited to contamination in the test plots. Therefore, the risk analysis does not consider possible contributions from "Cs that may have migrated beyond the test plots. Extend exposure to ioniziig radiation poses the majority of risk to the exposed populations rrd was duermincd to be the dominant pathway of concern for dl three scenarios. Tbe exposure scenarios examined in the pr dim ii hd th risk assessment WKC: 8 worker Who mOWS the Urn, 0 8 fishesmul/boateron the clinch fiver who comes Within 150 ft of the cesium 0 future onsite homesteader who lives inside the urn that is currently faced. Lifetime cancer risks rssociated with the WAG 13 cesium plots were Crlculated assuming rcpsonable maximum occupational exposure for the worker mowing the area, rusonable maximum exposure @ME) for 8 fishermadboater on the Clinch River, and RME for an on-site bomestder. RME assumptions for the preliminary health risk assessment were adopted from

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T h e RME scenario for the worker assumes that an individual rpcads 25 hlyear on-site for 25 years rad is exposed to an average gamma rate of 150 rwb measured on-site. "he RME .I?anl+in for tbe fishemidboater assumes that an individual spa& 52 Wycu (1 hlwak) on the Clinch River MU the WAG 13 cesium plots for 30 years rad is exposed to li muimUm gomma rrte of 19 pRh mwurod OD the Clinch River. ?be RME scemrio for tbe h u e on-site bomeftsrder assumes that an individwl spends 5600 h l y w (16h/d for 350 d) for 30 ycon inside the faxe and is exposed to an average gamma rate of 4 mwh. 'Ibe risk to the worker was estimated to be 1 x 10' (1 in loo0 chance of developing cancer). ?be risk to the fishwrmn/bopter on the Clinch River was esthated to be 2 x IO', and risk to the on-site homesteader was calculated to be 3 x 10'. Calculated risks from lifetime exposure to radionuclides and chemicals were compared to the EPA'r target risk range of 1 x lo6 to 1 x 1V. Any risk values greater than 1 X l(Y (1 in 10,OOO chances of developing cancer) we unacceptable, urd my risk values less than 1 x 1od (1 in 1,OOO,OOO chances of developing cancer) are acceptable by EPA. Acceptance of risks between 1 X 106 and 1 x l(r depends OD sitespecific conditions (i.e., population exposure). Tbe risk to the fishermanhater falls within EPA'r acceptable risk range. Although exposure to the worker is within DOE guidelines (DOE Order S480.1 I), risks to the worker mowing around the cesium plots and to the on-site homesteader exceed EPA'r target risk range. Ecological risk to plants and animals has not been quantitatively urplyred, but removal or shielding of the contaminated roil will have a positive bmefit for dl risk scenarios. The WAG 13 area will need further evaluation for the CERCLA Ecological Risk Assessment and Natural Resource Damage Assessment during the RI. If DO interim remedial mion is taken, rctual or threatened releases of hazardous rubstances from the WAG 13 cesium plots may present I current or potential threat to public health, welfare, or the environment. DESCRWIION OF ALTERNATIVES Wit section provides 1 description of bow each dteraiuive w u l d ddress the amtarnination found at WAG 13. Four alternatives are presented. These alternatives are not intended to remediate the entire WAG 13 site. Rather, they are intended to reduce the threat to human health, and to reduce further degradation of the environment resulting from elevated gamma radiation exposures. Remediation of the entire site will be addressed in future CERCLA

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CERCLA requires that the no-action olternative be evduated to m eur Wine for compuisoa at each site. Under this alternative, no further action would be taken to reduce the risk to human rocqtors from the current elevated levels of gamma radiation. impluneothg this dtefilltive would involve xi additional costs. Shielding involves placing reinford concrete boxes o v ~ea& cairn plot. Tbe boxes will deflect rad contain the gamma radiation within the box. After …