[en] During fourth quarter 1996, nine constituents exceeded final Primary Drinking Water Standards (PDWS) in groundwater samples from downgradient monitoring wells at the Mixed Waste Management Facility. No constituents exceeded final PDWS in samples from the upgradient monitoring wells. As in previous quarters, tritium and trichloroethylene were the most widespread elevated constituents. Carbon tetrachloride, chloroethene, chloroform, 1,1-dichloroethylene, dichloromethane, gross alpha, and tetrachloroethylene also exceeded final PDWS in one or more wells. Elevated constituents were found in numerous Aquifer Zone llB2 (Water Table) and Aquifer Zone llB1 (Barnwell/McBean) wells and in six Aquifer Unit IIA (Congaree) wells. The groundwater flow directions and rates in the three hydrostratigraphic units were similar to those of previous quarters