Air sparging case study database update

In situ air sparging is a commonly used remediation technology which was developed in the late 1980s as a method for treating dissolved volatile organic compounds (VOCs) in groundwater. Air sparging involves the injection of air under pressure into saturated zone soils. The injected air displaces water and creates air-filled porosity in the saturated soils, volatilizes and removes dissolved and adsorbed phase VOCs, and transfers oxygen into the groundwater. As a result, both physical removal and aerobic biodegradation of contamination in groundwater and saturated zone soil are enhanced. Air sparging offers a means of remediating soils and groundwater without the need for active groundwater pumping, and in some cases, air sparging has been shown to produce significant and permanent reductions in groundwater contaminant concentrations. As a result there has been a steady increase in application of air sparging, and hundreds of systems are currently in operation. However, dissolved groundwater concentrations sometimes fall dramatically during sparging, but then rebound nearly to original levels once the sparge system is turned off. In this paper, the results of 32 sparging case studies are compiled to shed light on how well and under what conditions air sparging achieves permanent reduction in groundwater contaminant concentrations.more » Pollutants of concern include BTEX and chlorinated solvents.« less