MODELING ALTERNATIVE GROUNDWATER REMEDIATION METHODS IN CONTRASTING HYDROGEOLOGIC SETTINGS

A contaminant fate and transport model was used to simulate the effect s of 11 remediation schemes on benzene plumes in three hydrogeologic s ettings. Pump and treat, bioremediation, and a combination of those te chnologies were considered. Dissolved oxygen concentrations of 8 and 5 0 mg/l were used at injection wells. The simulated aquifers include sa nd and gravel, silty sand, and clayey sand. Interior injection (50 mg/ l O-2) was most successful overall, consistently attaining the highest rank in each setting. Interior extraction/exterior injection (50 mg/l O-2) ranked second overall. Whether used for injection or extraction, interior well configurations generally outperformed alternative patte rns. Interior extraction, the most successful pump and treat scheme, p erformed effectively in the sand and gravel aquifer, but was among the lowest ranking schemes in the lower velocity settings. In contrast, i nterior injection (8 mg/l O-2) performed better in the low velocity aq uifers. Consistently, downgradient extraction and no action were the l east effective schemes.