The U.S. Department of Energy (DOE) and the U. S. Environmental Protection Agency (EPA) are working together to justify a change in the Land Disposal Restriction for High Mercury (>260 ppm mercury) waste. The present regulation that requires roasting or retorting is based on recovering and recycling the mercury in the waste. However, most of DOE’s High Mercury waste is radioactively contaminated, eliminating the possibility of its recycle. The radioactive mercury recovered must be amalgamated and disposed. In addition, concern over fugitive emissions from retorting and roasting operations has raised the question of whether such processing is environmentally sound. A change to the regulation to allow stabilization and disposal would reduce the overall environmental threat, if the stabilization process can reduce the leachability of the mercury to regulatory levels. Demonstrations are underway to gather data showing that the High Mercury waste can be safely stabilized. At the same time, comparison tests are being conducted using an improved form of the baseline retorting technology to better quantify the fugitive emission problem and determine the full capability of thermal desorption systems. A first round of demonstrations stabilizing mercury in soil from Brookhaven National Laboratory (BNL) has been completed. Four groups demonstrated their process on the waste: 1) BNL demonstrated its Sulfur Polymer Stabilization/Solidification process; 2) Nuclear Fuel Services used their DeHg (de-merk) process, 3) Allied Technology Group used chemical stabilization, and 4) Sepradyne demonstrated their vacuum thermal desorption system. All groups were successful in their tests, reaching regulatory levels for mercury leachability. Data for each group will be presented. DOE, EPA, and the University of Cincinnati are presently working on another series of tests involving treatment of surrogate sludge and soil by commercial vendors. Protocols that better determine the waste form’s ability to withstand leaching are being used to analyze the stabilized surrogates. Results of these and the previous demonstrations will be used to determine whether the High Mercury treatment regulation can be safely changed
