[en] Forty-eight locations were identified that received a variety of radioactive and nonradioactive constituents during the past 35 years including surface impoundments and shallow land burial facilities. Detailed environmental assessments of existing waste disposal areas, as well as new waste disposal techniques and disposition of tritiated water, were completed to air in an evaluation of the low level, mixed and hazardous waste management activities. These assessments result in estimation of risk, or residual risk, posed by each disposal area to various receptors as a function of waste management alternative. For example, at existing waste sites, the closure actions evaluated were waste removal and closure, no waste removal and closure, and no action; several pathways/receptors were considered, including groundwater to river, groundwater to well, atmospheric transport, occupational exposure, direct exposure, and contamination followed by ingestion of crops and meat. Modeling of chemical transport in a variety of media was an integral part of the assessment process. The quality of the models used and the application of these models were assured by an explicit quality assurance program