The dense subsurface infrastructure of the site made the conventional practice of extracting the contaminated groundwater very difficult, so we suggested injecting ozone into the soil to promote degradation of the polyaromatic hydrocarbons as an alternative. In the Solvis process, polluted soil is passed through these pipes by endless screws in a countercurrent of solvent that strips them of contaminants, which are combusted elsewhere. Southern California Edison chose IT Corp. to build the remediation system, because of the environmental engineering company's experience in building four full-scale ozonation systems and six pilot scale systems to treat similar contaminants under similar site conditions. In October 1998, IT Corp. engineers sank 31 vertical sparging points throughout the plume of contamination at the Long Beach site. The sparging points are made of corrosion-resistant Teflon tubing for most of their length, with the lower 25 feet made of 316 stainless steel rods wrapped with stainless steel wire mesh.
Ozone is distributed through the screened portion of each point.
The company also placed four horizontal sparging points through the center of the plume approximately six feet beneath the water table. Using a pure oxygen gas source, these machines generate an electric corona around ceramic dielectric components to produce a total of 52 pounds of ozone daily. The injection gas, containing five to 10 percent ozone and 90 to 95 percent oxygen, is delivered through the sparging points into the ground at rates as fast as 7.5 cubic feet per minute, at 20 pounds per square inch pressure. IT Corp. Dablow managed the design, construction, and operation of the Long Beach on-site ozone treatment system. Monthly groundwater and quarterly soil samples are extracted from the monitoring wells for off-site laboratory analysis.