UMTRA nonradiological toxins cleanup methodology (DECHEM)

Remedial investigations at Uranium Mill Tailings sites have indicated that metallic toxicants may be more mobile than the radiological constituents that have generally been emphasized in remedial planning. Regulatory guidelines are presently lacking for the cleanup of metallic toxicants from subpile soils or adjacent areas of windborne or waterborne contamination. A procedure has been developed in support of the Uranium Mill Tailings Remedial Action (UMTRA) Project to guide the characterization and remedial planning for these elements at twenty-four UMTRA Project sites. The procedure generates site-specific cleanup criteria based on acceptable levels of health risk associated with exposure to the most hazardous toxicants. At the heart of the procedure is a pathway analysis approach for determining the acceptable residual levels of metallic toxicants that may remain in the soil after a remedial action has been completed. The analysis utilizes a technique names DECHEM that closely parallels the DECOM method already developed for radionuclides at mixed waste sites. The methodology employs user-friendly microcomputer software that permits the insertion of site-specific parameters to guide the characterization and management of metallic toxicants at a given mill tailings site. DECHEM has been implemented on a trial basis at two UMTRA Project sites: Green River, Utah and Riverton, Wyoming