Title: Sensitivity Analysis of Contaminant Transport from Vadose Zone Sources to Groundwater
Abstract: Remedy selection and implementation in the Central Plateau of the Hanford Site will be facilitated by a technically defensible description of vadose zone sources and their spatial and temporal impacts on groundwater. To this end, a case study approach is used to assess impacts to groundwater associated with uncertainties in source terms and hydraulic and sorption parameters for the B-Complex at Hanford. Several unplanned releases of wastes occurred in the tanks in the B-Complex. Several planned liquid waste discharges also occurred to cribs, trenches, tile fields, and French drains within the B-Complex, creating a significant inventory of contaminants in the vadose zone whose downward migration in the subsurface pose a potential threat to groundwater. Given the uncertainty in multiple source locations, volumes and intensities, and uncertainties in hydraulic and sorption properties, an integrated assessment of their combined effects is needed to guide characterization, support selection of appropriate remedies, and design appropriate monitoring for vadose zone source areas and the underlying aquifer.