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Title: Consideration of liners and covers in performance assessments

On-site disposal cells are in use and being considered at several United States Department of Energy (USDOE) sites as the final disposition for large amounts of waste associated with cleanup of contaminated areas and facilities. These disposal cells are typically regulated by States and/or the U.S. Environmental Protection Agency under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) in addition to having to comply with requirements in DOE Order 435.1, Radioactive Waste Management due to the radioactive waste. The USDOE-Environmental Management Office of Site Restoration formed a working group to foster improved communication and sharing of information for personnel associated with these CERCLA disposal cells and work towards more consistent assumptions, as appropriate, for technical and policy considerations related to CERCLA risk assessments and DOE Order 435.1 performance assessments in support of a Record of Decision and Disposal Authorization Statement, respectively. One of the issues considered by the working group, which is addressed in this report, was how to appropriately consider the performance of covers and liners/leachate collections systems in the context of a DOE Order 435.1 performance assessment (PA). This same information may be appropriate for consideration within CERCLA risk assessments for these facilities. These OSDCs are generallymore » developed to meet hazardous waste (HW) disposal design standards under the Resource Conservation and Recovery Act (RCRA) as well as the DOE Order 435.1 performance based standards for disposal of radioactive waste. To meet the standards for HW, the facilities typically include engineered covers and liner/leachate collection systems. Thus, when considering such facilities in the context of a DOE Order 435.1 PA, there is a need to address the evolution of performance of covers and liner/leachate collection systems in the context of meeting a performance standard considering time frames of 1,000 years for compliance and potentially thousands of years based on the wastes to test the robustness of the system. Experience has shown that there are a range of expectations and perspectives from the different regulators involved at different sites when reviewing assumptions related to cover and liner/leachate collection system performance. However for HW disposal alone under RCRA the design standards are typically considered sufficient by the regulators without a requirement to assess long-term performance thus avoiding the need to consider the details addressed in this report. This report provides suggestions for a general approach to address covers and liners/leachate collection systems in a DOE Order 435.1 PA and how to integrate assessments with defense-in-depth considerations such as design, operations, and waste acceptance criteria to address uncertainties. The emphasis is on water balances and management in such assessments. Specific information and references are provided for details needed to address the evolution of individual components of cover and liner/leachate collection systems. This information was then synthesized into suggestions for best practices for cover and liner system design and examples of approaches to address the performance of covers and liners as part of a performance assessment of the disposal system. Numerous references are provided for sources of information to help describe the basis for performance of individual components of cover and liner systems.« less
 [1] ;  [1] ;  [2]
  1. Savannah River National Laboratory, Aiken, SC (United States)
  2. USDOE Enviromental Management, Washington, DC (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
TRN: US1400451
DOE Contract Number:
Resource Type:
Technical Report
Research Org:
Savannah River Site (SRS), Aiken, SC (United States)
Sponsoring Org:
Country of Publication:
United States