Contaminant transport in unconfined aquifer, input to low-level tank waste interim performance assessment

This report describes briefly the Hanford sitewide groundwater model and its application to the Low-Level Tank Waste Disposal (LLTWD) interim Performance Assessment (PA). The Well Intercept Factor (WIF) or dilution factor from a given areal flux entering the aquifer released from the LLTWD site are calculated for base case and various sensitivity cases. In conjunction with the calculation for released fluxes through vadose zone transport,the dose at the compliance point can be obtained by a simple multiplication. The relative dose contribution from the upstream sources was also calculated and presented in the appendix for an equal areal flux at the LLTWD site. The results provide input for management decisions on remediation action needed for reduction of the released fluxes from the upstream facilities to the allowed level to meet the required dose criteria