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Title: Hydraulic Isolation of Waste Disposal Areas at Oak Ridge National Laboratory

Abstract

The Melton Valley watershed at Oak Ridge National Laboratory (ORNL) is the location of several large waste disposal areas that received waste from more than 50 years of operation, production, and research activities at ORNL and the U.S. Atomic Energy Commission's Southern Regional Burial Ground for wastes from more than 50 other facilities. The major burial grounds in the valley are Solid Waste Storage Areas (SWSAs) 4, 5, and 6, where wastes were buried in more than 850 unlined trenches and more than 1500 unlined auger holes. The area includes 3 seepage pits and 3 gravel-filled trenches used by ORNL for the disposal of liquid low level wastes. The burial grounds contained several hundred thousand cubic yards of waste, and the combined inventory of the burial grounds and liquid disposal sites was well over 1 million curies. The Record of Decision for Interim Actions for the Melton Valley Watershed at ORNL selected hydraulic isolation of major waste sources as the primary mechanism for remediation of the watershed. Isolation was to be accomplished mainly through the construction of multi-layer caps over the burial grounds, seepage pits, and trenches. Groundwater diversion and collection systems were installed along the up-gradient and down-gradient edges,more » respectively, of selected caps to enhance the performance of the isolation system. The waste areas were covered with both Resource Conservation and Recovery Act (RCRA)-type and isolation multi-layer caps. A total of 13 multi-layer caps covering 58.7 hectares (ha) (plan view) were constructed in Melton Valley between 2003 and 2006. The project encountered considerable challenges, not the least of which was its scale, involving simultaneous construction activities at widely scattered sites across the 430-ha watershed. Detailed planning and coordination enabled year-round fieldwork, an essential requirement necessary to retain a skilled, experienced workforce and meet the contract milestone for completion. Other factors key to the success of the project involved the use of an on-site borrow area and construction of a dedicated haul road for transfer of materials from the borrow area to the capping sites. In summary: Remedy effectiveness data obtained during 2007 for the Melton Valley ROD actions collectively indicate that the remedy is generally operating and functioning as planned. Contaminant releases of the principal contaminants of concern in Melton Valley have decreased significantly during and since remediation of the contaminant source areas. Hydrologic isolation systems at the burial grounds functioned as intended as demonstrated by attainment of groundwater level goals in most areas. (authors)« less

Authors:
; ;  [1];  [2]; ;  [3]
  1. Bechtel Jacobs Company LLC, Oak Ridge, TN (United States)
  2. B and W Technical Services Y-12 LLC, National Security Complex, Oak Ridge, TN (United States)
  3. United States Department of Energy, Oak Ridge Operations Office, Oak Ridge, TN (United States)
Publication Date:
Research Org.:
WM Symposia, 1628 E. Southern Avenue, Suite 9 - 332, Tempe, AZ 85282 (United States)
OSTI Identifier:
21319798
Report Number(s):
INIS-US-10-WM-08452
TRN: US10V0625061989
Resource Type:
Conference
Resource Relation:
Conference: 2008 Waste Management Symposium - WM2008/WM'08: HLW, TRU, LLW/ILW, Mixed, Hazardous Wastes and Environmental Management - Phoenix Rising: Moving Forward in Waste Management, Phoenix, AZ (United States), 24-28 Feb 2008; Other Information: Country of input: France
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; GROUND WATER; LOW-LEVEL RADIOACTIVE WASTES; ORNL; RADIOACTIVE WASTE DISPOSAL; RADIOACTIVE WASTE STORAGE; REMEDIAL ACTION; SOLID WASTES

Citation Formats

Cater, F., Cange, J.B., Lambert, R.K., Spurling, R., Julius, J.F.K., and Skinner, R.. Hydraulic Isolation of Waste Disposal Areas at Oak Ridge National Laboratory. United States: N. p., 2008. Web.
Cater, F., Cange, J.B., Lambert, R.K., Spurling, R., Julius, J.F.K., & Skinner, R.. Hydraulic Isolation of Waste Disposal Areas at Oak Ridge National Laboratory. United States.
Cater, F., Cange, J.B., Lambert, R.K., Spurling, R., Julius, J.F.K., and Skinner, R.. 2008. "Hydraulic Isolation of Waste Disposal Areas at Oak Ridge National Laboratory". United States. doi:.
@article{osti_21319798,
title = {Hydraulic Isolation of Waste Disposal Areas at Oak Ridge National Laboratory},
author = {Cater, F. and Cange, J.B. and Lambert, R.K. and Spurling, R. and Julius, J.F.K. and Skinner, R.},
abstractNote = {The Melton Valley watershed at Oak Ridge National Laboratory (ORNL) is the location of several large waste disposal areas that received waste from more than 50 years of operation, production, and research activities at ORNL and the U.S. Atomic Energy Commission's Southern Regional Burial Ground for wastes from more than 50 other facilities. The major burial grounds in the valley are Solid Waste Storage Areas (SWSAs) 4, 5, and 6, where wastes were buried in more than 850 unlined trenches and more than 1500 unlined auger holes. The area includes 3 seepage pits and 3 gravel-filled trenches used by ORNL for the disposal of liquid low level wastes. The burial grounds contained several hundred thousand cubic yards of waste, and the combined inventory of the burial grounds and liquid disposal sites was well over 1 million curies. The Record of Decision for Interim Actions for the Melton Valley Watershed at ORNL selected hydraulic isolation of major waste sources as the primary mechanism for remediation of the watershed. Isolation was to be accomplished mainly through the construction of multi-layer caps over the burial grounds, seepage pits, and trenches. Groundwater diversion and collection systems were installed along the up-gradient and down-gradient edges, respectively, of selected caps to enhance the performance of the isolation system. The waste areas were covered with both Resource Conservation and Recovery Act (RCRA)-type and isolation multi-layer caps. A total of 13 multi-layer caps covering 58.7 hectares (ha) (plan view) were constructed in Melton Valley between 2003 and 2006. The project encountered considerable challenges, not the least of which was its scale, involving simultaneous construction activities at widely scattered sites across the 430-ha watershed. Detailed planning and coordination enabled year-round fieldwork, an essential requirement necessary to retain a skilled, experienced workforce and meet the contract milestone for completion. Other factors key to the success of the project involved the use of an on-site borrow area and construction of a dedicated haul road for transfer of materials from the borrow area to the capping sites. In summary: Remedy effectiveness data obtained during 2007 for the Melton Valley ROD actions collectively indicate that the remedy is generally operating and functioning as planned. Contaminant releases of the principal contaminants of concern in Melton Valley have decreased significantly during and since remediation of the contaminant source areas. Hydrologic isolation systems at the burial grounds functioned as intended as demonstrated by attainment of groundwater level goals in most areas. (authors)},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2008,
month = 7
}

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  • White Oak Creek and Melton Branch tributary surface streams flow through the Oak Ridge National Laboratory (ORNL) reservation and receive treated low-level radioactive liquid waste which originates from various Laboratory operations. The streams receive additional low-level liquid waste generated by seepage of radioactive materials from solid-waste burial grounds, hydrofracture sites, and intermediate-level liquid-waste sites. Over the years, various liquid-waste treatment and disposal processes have been employed at ORNL; some of these processes have included: settling basins, impoundment, storage tanks, evaporation, ground disposal in trenches and pits, and hydrofracture. Burial of solid radioactive waste was initiated in the early 1940's, andmore » there are six burial grounds at ORNL with two currently in use. Monitoring at White Oak Dam, the last liquid control point for the Laboratory, was started in the late 1940's and is continuing. Presently, a network of five environmental monitoring stations is in operation to monitor the radionuclide content of surface waters in the White Oak watershed. In this paper, the solid waste burial grounds will be described in detail, and the environmental data tabulated over the past 29 years will be presented. The various monitoring systems used during the years will also be reviewed. The liquid effluent discharge trends at ORNL from the radioactive waste operations will be discussed.« less
  • Low-level liquid nuclear wastes are disposed of at Oak Ridge National Laboratory by the hydrofracture process. Wastes are mixed with cement and other additives to form a slurry that is injected into shale of low permeability at 300 m depth. The slurry spreads radially along bedding plane fractures before setting as a grout. Different methods for monitoring the location and behavior of the fractures have been investigated. Radioactive grout sheets can be located by gamma-ray logging of cased observation wells. Two other methods are based on the fact that the ground surface is deformed by the injection. The first entailsmore » surface leveling of a series of benchmarks; uplift up to 2.5 cm occurs. The second method involves use of tiltmeters that are sensitive and measure ground deformation in real time during an injection. Both methods show subsidence during the weeks following an injection. Interpretive models for the tiltmeter data are based on the elastic response of isotropic and anisotropic media to the inflation of a fluid-filled fracture. A fourth monitoring method is based on microseismicity. Geophone arrays were used to characterize the fracture process and to provide initial assessment of the feasibility of using seismic measurements to map the fractures as they form. An evaluation of each method is presented. 8 refs., 6 figs.« less
  • At Oak Ridge National Laboratory the Pumpkin Valley Shale is used as a host formation for hydraulic-fracturing waste disposal. Determination of the relationships between the distribution of different lithologies and porosity-permeability trends within this host formation allows these properties, important to hydraulic-fracturing operations, to be related to measurable and mappable geological and petrological parameters. It also permits extrapolation of such patterns to little-studied portions of the Pumpkin Valley Shale. Such knowledge better allows for the satisfactory operation and assessment of the hydraulic fracturing at Oak Ridge National Laboratory.
  • In the early to mid-1960's, liquid low-level wastes (LLLW) generated at Oak Ridge National Laboratory were disposed of in specially-constructed, gravel-filled trenches within the Melton Valley watershed at the lab. The initial selected remedy for Trenches 5 and 7 was in situ vitrification; however, an amendment to the record of decision changed the remedy to in situ grouting of the trenches. The work was accomplished by filling the void space within the crushed stone section of each trench with cementitious grout. The contaminated soil surrounding the trenches (1-m perimeter) was then grouted with acrylamide grout. At the HRE fuel wells,more » a 1-m ring of soil surrounding the fuel wells was grouted with acrylamide. The results of the hydraulic conductivity tests ranged from 4.74 x 10{sup -6} to 3.60 x 10{sup -7} cm/sec, values that were well below the 1 x 10{sup -5} cm/sec design criterion. In summary: The ISG Project was conducted to decrease hydraulic conductivity and thereby decrease water flow and contaminate migration from the area of the trenches. The initial remedy for Trenches 5 and 7 in the Melton Valley ROD was for in situ vitrification of the trench matrix. The remedy was changed to in situ grouting of the trenches and HRE fuel wells through an amendment to the ROD after moisture was found in the trenches. The grouting of the trenches was accomplished by filling the void space within the crushed stone section of each trench with cementitious grout. The contaminated soil surrounding the trenches (1-m perimeter) was then grouted with acrylamide grout to further reduce water infiltration. Soil backfill above each of the seven HRE fuel wells was removed to a depth of approximately 1 m by augering, and the soils were replaced with a cement plug to prevent water infiltration from migrating down the original borehole. Soil surrounding the fuel wells was then grouted with acrylamide to ensure water infiltration through the HRE fuel wells is prevented. A summary of the quantities used is shown. After completion of grouting, in-situ hydraulic conductivities of the grouted materials were measured to verify attainment of the design objective. The areas were then covered with multi-layer caps as part of the MV hydrologic isolation project. (authors)« less
  • Thermoluminescent dosimeters (TLDs) were used to determine dose equivalent rates in the ORNL solid waste disposal areas. The dosimeters were exchanged and read approximately quarterly during 1979 and 1980. The data were reviewed to detect trends in dose equivalent rates, but no trends were detected other than increased radiation levels in some areas due to the lowering of White Oak Lake. The rates at the disposal site were compared with TLD readings taken in areas on the DOE reservation perimeter, as well as in remote areas that represent natural background for East Tennessee.