Kleinfelder developed a groundwater remediation system to clean up a 6-acre, 140-foot deep contaminant plume that extended beneath a major freeway and residential areas in California. The client was concerned not only with an effective cleanup, but also with public relations for this very high profile, unpopular project.

The contaminants in the source area—benzene, toluene, ethylbenzene, and xylene—are volatile and readily degradable, so Kleinfelder remediation specialists chose air sparging to clean up groundwater, and vapor extraction to clean up soils.

The predominant contaminants at the leading edge of the plume – 1,2-DCA and MTBE – are not easily degraded, but are readily oxidized. Ozone sparging was therefore used to attack the leading edge of the plume. By using horizontal directional drilling, Kleinfelder’s subcontractor was able to install ozone delivery lines 15 feet below the freeway. At the other end, they drilled 25 feet vertically upward, and, from this location, drilled horizontally beneath roads to locations where they installed the ozone injection wells. In this manner, the wells could be installed unobtrusively in public rights-of-way within the residential areas.