AIR MIGRATION AND CHANGE OF CONTAMINANT CONCENTRATION IN GROUNDWATER INDUCED BY IN SITU AIR SPARGING

The in situ air sparging technology, devised to facilitate contaminant volatilization with air injected into groundwater, was applied to a site contaminated with volatile organochlorines like tetrachloroethylene, carbon tetrachloride, chloroform etc. These substances were utilized to produce chemicals for many years. This paper examined air migration in groundwater, influence radius of sparging air and change of contaminant concentration due to air sparging technology. In this site, the mounding test was carried out to reveal detailed air migration in groundwater. As a result, the influence radius of sparging air was within 14m and sparging air smoothly flowed in groundwater. And, in the in situ air sparging, the contaminant concentrations decreased at some observation wells in the domain of influence radius of sparging air. In particular, carbon tetrachloride, the Henry's constant of which was the highest among substances specified, decreased appreciably.