his report describes a computer application that was developed to assess impacts to groundwater caused by leaching of trace elements from CCPs used in highway construction. Laboratory and field experiments conducted to verify the application are also described. The application, referred to as WiscLEACH, is based on three analytical solutions to the advection-dispersion-reaction equation that describe transport in the vadose zone and groundwater. The application was designed to be computationally efficient and can be used without experience in numerical modeling. Predictions made with WiscLEACH indicate that maximum groundwater concentrations of trace elements leached from CCPs typically occur close to the groundwater table and near the center line of the pavement structure. Peak groundwater concentrations decrease as the depth to groundwater increases, the thickness of the byproducts layer decreases, the seepage velocity in the vadose zone decreases, or the seepage velocity in groundwater increases. Parametric studies have shown that the variables having the greatest influence on maximum concentrations in groundwater are depth to the groundwater table, thickness of the CCP layer, hydraulic conductivity of the least conductive layer in the vadose zone, hydraulic conductivity of the aquifer material,and the initial concentration in the CCP layer.
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