Application of 3DFEMWATER to assess capping alternatives at a steep-slope hazardous waste disposal site

A saturated/unsaturated groundwater flow simulator, 3DFEMWATER was used to model the Waste Area Grouping 6 (WAG 6) waste site at Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee. The model was used to quantitatively predict the response of the groundwater system to various surface capping scenarios and to determine an optimal cap placement strategy that maximizes water table decline in the disposal areas and reduces off-site contaminant flux. 3DFEMWATER was selected because of its ability to simulate saturated/unsaturated flow conditions on the steep slopes at the site. This flow may enter capped area and affect the efficiency of the caps. This paper presents details about 3DFEMWATER, the modeling process employed, and results. Details are presented about the geologic and hydrogeologic site conditions for the modeling