Modeling alternative groundwater remediation methods in contrasting hydrogeologic settings

Abstract

A contaminant fate and transport model was used to simulate the effects of 11 remediation schemes on benzene plumes in three hydrogeologic settings. Pump and treat, bioremediation, and a combination of those technologies were considered. Dissolved oxygen concentrations of 8 and 50 mg/l were used at injection wells. The simulated aquifers include sand and gravel, silty sand, and clayey sand. Interior injection (50 mg/l O₂) was most successful overall, consistently attaining the highest rank in each setting. Interior extraction/exterior injection (50 mg/l O₂) ranked second overall. Whether used for injection or extraction, interior well configurations generally outperformed alternative patterns. Interior extraction, the most successful pump and treat scheme, performed effectively in the sand and gravel aquifer, but was among the lowest ranking schemes in the lower velocity settings. In contrast, interior injection (8 mg/1 O2) performed better in the low velocity aquifers. Consistently, downgradient extraction and no action were the least effective schemes.

Key words:

• groundwater remediation
• gasoline contamination