Field analysis: Physical and biological BTEX removal in a sandy aquifer

A sandy aquifer contaminated with dissolved phase BTEX compounds is currently being remediated through a combination of physical processes (pump and treat) and enhanced in-situ biodegradation. Extensive data collected from site monitoring and pump-back wells, along with knowledge of site sorptive and hydrodynamic properties, allowed the calculation of a contaminant mass balance, from which in-situ biotransformation was estimated. Data indicates that pump and treat removals of dissolved BTEX accounts for approximately half of the total reduction in BTEX mass on the site. Oxygen utilization data implicates biodegradation as responsible for the majority of remaining contaminant mass removal. Contaminant reductions in-situ appear to be associated with zones of increased contaminant-oxygen mixing located immediately downgradient from site injection wells.