Vapor extraction and air sparging for cleanup of gasoline, benzene and MTBE

After conducting a series of soil and groundwater investigations at one vacant and one active municipal maintenance facility, Lindmark Engineering carried out a remedial investigation and feasibility study in which several options were explored and evaluated for cost and timeliness. The needs were especially pressing for one of the sites because it was slated for development into a movie studio. We recommended an approach involving product recovery, vapor extraction, and air sparging, and installed systems at both sites to remediate high levels of gasoline and associated compounds in the subsurface.

The vacant facility was successfully remediated in six months and closed by the California Regional Water Quality Control Board (Regional Board). The site that was an active maintenance facility had subsequent gasoline and releases of methyl tertiary butyl ether (MTBE) after we had designed the remediation system. Due to these releases, we installed additional vapor extraction and air-sparging wells to facilitate extraction of contaminants and containment of the plume. The system was highly effective and recovered over 16,000 pounds of gasoline from soil and groundwater. The plume, which was shown to be stable, was completely contained within the property, and our monitoring showed it to be attenuating naturally.

Because of the site’s proximity to future municipal water-supply wells, Lindmark Engineering had to perform hydrogeologic investigations that included analytical groundwater modeling and developing a site conceptual MTBE model. Due to municipal well extraction in the immediate site vicinity, the Regional Board put a very high priority on the site. However, we were able to show that the site had been adequately remediated and did not pose a threat to the underlying water supply, and the Regional Board issued regulatory closure. Subsequently, the site was successfully redeveloped for a higher use.

For more information regarding this project, please contact Lindmark Engineering.