Air sparging coupled with soil vapor extraction has been developed and applied to remove volatile contaminants from subsurface environment instead of groundwater extraction coupled with soil vapor extraction. The groundwater extraction requires water treatment like aeration on the ground. On the other hand, air sparging facilitates contaminant volatilization with air injected into groundwater and removes contaminant gas by soil vapor extraction in the unsaturated zone. Additionally, this technology accelerates aerobic biodegradation of contaminants like petroleum hydrocarbons by increasing dissolved oxygen concentrations in groundwater. This paper presented the results of the field test conducted to estimate the removal effect of volatile organic compounds with air injection into groundwater. The summary was as follows. Toluene and tetrachloroethylene concentration in groundwater smoothly decreased and were below the environmental quality standard within the zone of influence of injected air. Toluene concentration in groundwater decreased due to volatilization and aerobic biodegradation. And in the aerobic zone, biodegradation rate was larger than volatilization rate.
