Integrated ecological and human health risk assessments for the U.S. Department of Energy's Hanford Site

Assessment of ecological and human health risk over large spatial scales benefits from a common contaminant data set and subdivision of the site into smaller pieces. Two integrated, modular risk assessments were prepared for the US Department of Energy's Hanford Site, near Richland, WA. The Site covers an area of about 143,000 ha. Two environmental impact statements focus on remediation of more than 1,100 past practice waste sites and remediation of high-level nuclear wastes stored in 177 tanks. The past-practice sties are distributed over a large fraction of the site. The tanks are located in the Central Plateau, an area of about 50,000 ha. Contaminant data are available primarily as waste inventories, rather than as environmental media concentrations. To cope with large physical scales and limited data, source terms were estimated from waste inventory data aggregated within