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

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:
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
Research Org:
WM Symposia, 1628 E. Southern Avenue, Suite 9 - 332, Tempe, AZ 85282 (United States)
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