Assessment of Biodegradation Processes at a Complex Site: Decision Strategy and Implications for Enhanced Bioremediation (PDF)
A Superfund site in Ohio overlies groundwater contaminated with chlorinated aliphatic hydrocarbons (CAHs)—including perchloroethene (PCE), trichloroethene (TCE), cis-1,2- dichloroethene (DCE), and vinyl chloride (VC) — from prior solvent use and disposal in onsite ponds. The ponds and surface soils containing CAHs were removed in 1984. Historical solvent use and disposal practices produced a shallow groundwater contaminant plume (10' – 40' bgs) that has migrated 3,500 feet downgradient in a highly transmissive aquifer. A groundwater pump-and-treat system (P&T) installed in 1987 continues to effectively remove dissolved-phase CAHs and provide plume control, thereby protecting a municipal well field located one-mile downgradient from the source areas. However, dissolved phase CAH concentrations have not declined significantly despite over 10 years of active P&T and considerable CAH mass removal.