Remedial investigation report on waste area grouping 5 at Oak Ridge National Laboratory, Oak Ridge, Tennessee. Volume 4, Appendix C, Risk assessment

Waste Area Grouping (WAG) 5 is part of Oak Ridge National Laboratory (ORNL) and is located on the United States Department of Energy's Oak Ridge Reservation (DOE-ORR). The site lies southeast of Haw Ridge in Melton Valley and comprises approximately 32 ha (80 ac) [12 ha (30 ac) of forested area and the balance in grassed fields]. Waste Area Grouping 5 consists of several contaminant source areas for the disposal of low-level radioactive, transuranic (TRU), and fissile wastes (1959 to 1973) as well as inorganic and organic chemical wastes. Wastes were buried in trenches and auger holes. Radionuclides from buried wastes are being transported by shallow groundwater to Melton Branch and White Oak Creek. Different chemicals of potential concern (COPCs) were identified (e.g., cesium-137, strontium-90, radium-226, thorium-228, etc.); other constituents and chemicals, such as vinyl chloride, bis(2-ethylhexyl)phthalate, trichloroethene, were also identified as COPCs. Based on the results of this assessment contaminants of concern (COCs) were subsequently identified. The objectives of the WAG 5 Baseline Human Health Risk Assessment (BHHRA) are to document the potential health hazards (i.e., risks) that may result from contaminants on or released from the site and provide information necessary for reaching informed remedial decisions. As part of the DOE-Oak Ridge Operations (ORO), ORNL and its associated waste/contamination sites fall under the auspices of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), also known as Superfund under the Superfund Amendments and Reauthorization Act (SARA). The results of the BHHRA will (1) document and evaluate risks to human health, (2) help determine the need for remedial action, (3) determine chemical concentrations protective of current and future human receptors, and (4) help select and compare various remedial alternatives.