[en] The major objectives of this investigation are: (1) to study the attenuation mechanisms for radionuclides (LLRW) in simulated sanitary landfills with and without leachate recycle; and (2) to determine the complexation potential of ligands (viz., sulfides, humic substances) present in the leachate during different stages of landfill stabilization. Since the major emphasis of this research is on containment and isolation of LLRW within a sanitary landfill the following key elements have been incorporated into the design of the simulated pilot-scale sanitary landfills: (1) containment of LLRW within the landfills by placing the municipal refuse and LLRW in polymeric membrane-lined cells (30-mil, HDA, Gundline liner, Gundle, TX) with a leachate collection system; (2) enhancement of stabilization by leachate recycle; and (3) recovery of the gas produced from the sanitary landfills. The proposed research program addresses the fate of LLRW in municipal sanitary landfills thereby, establishing a data base to predict radionuclide pathways in sanitary landfills and to aid in assessing the environmental impacts of codisposal of LLRW within sanitary landfills. The outcome of this study may also serve to alleviate the current concern of unnecessary filling of limited space in existing licensed shallow-land burial sites. 4 figures, 1 table