Superfund Innovative Technology Evaluation (SITE)
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Solvent Extraction Technology
Terra-Kleen Response Group, Inc.
Terra-Kleen Response Group, Inc. (Terra-Kleen) has developed a solvent extraction technology to remove organic contaminants from soil. The U.S. Environmental Protection Agency (EPA) Superfund Innovative Technology Evaluation (SITE) Program evaluated the performance of this technology during a demonstration at Site 4 of Naval Air Station North Island (NASNI) in San Diego, California in May and June 1994. This Innovative Technology Evaluation Report (ITER) describes the technology and environmental requirements, an economic analysis of treatment costs, and an evaluation of the performance of the technology during the SITE demonstration.The Terra-Kleen technology employs a proprietary solvent that extracts organic contaminants from contaminated soil. Following this extraction, the organic-laden solvent is then filtered and purified, using a proprietary purification unit. Regenerated solvent is continuously recycled through the contaminated soil until a target cleanup level is achieved. Any solvent remaining in the treated soil is removed using vacuum extraction and biological treatment. Terra-Kleen claims that its treatment process removes polychlorinated biphenyls (PCB), petroleum hydrocarbons, chlorinated hydrocarbons, polynuclear aromatic hydrocarbons, polychlorinated dibenzo-p-dioxins, polychlorinated dibenzo-p-furans, and metals from contaminated soil. An initial treatability study was conducted to determine the technology's ability to remove PCBs from soil collected from three sites that was shipped to Terra-Kleen's testing facility in Okmulgee, Oklahoma. These soils were obtained from Sites 4 and 6 at Naval Air Station North Island (NASNI) in Coronado, California, and from a site in Anchorage, Alaska. Results from treated soil showed that PCB removal efficiency ranged from 95.3 to 99.1 percent. PCB concentrations in treated soils from both the NASNI sites were reduced to below the Toxic Substances Control Act incineration equivalency concentration of 2 milligrams per kilogram (mg/kg). The Alaskan soil contained a higher percentage of fines, clay, and natural organic matter, a fact that contributed to the higher number of extraction cycles needed to reduce PCB concentrations to 6.0 mg/kg. The Terra-Kleen technology was demonstrated under the SITE Program at NASNI in May and June 1994. The demonstration provided information on the performance and cost of the Terra-Kleen technology. Analytical results for treated soil showed that PCB concentrations of 144 mg/kg in contaminated soil were decreased to less than 1.7 1 mg/kg with a significance level of 0.05, for an overall removal efficiency of 98.8 plus or minus 0.1 percent. Untreated and treated soils were also analyzed for parameters such as oil and grease, volatile organic compounds, semivolatile organic compounds, dioxins, and furans to determine the Technology's ability to remediate soils contaminated with these constituents. Sampling results indicated that the technology removed 66.3 plus or minus 5.47 percent of the oil and grease, and reduced hexachlorodibenzofurans and pentachlorodibenzofurans by 92 plus or minus 0.82 percent and 76 plus or minus 5.28 percent, respectively. After the SITE demonstration, the SITE Program collected soil samples during a full-scale remediation of pesticide-contaminated soils at Naval Communication Station Stockton in Stockton, California. Soil at different sites on the installation were contaminated with DDD, DDE, and DDT at concentrations of 150, 50, and 600 mg/kg, respectively. Percent removals for all three pesticides ranged from 99.4 to 99.9 percent. An economic analysis for the Terra-Kleen SITE demonstration was based on theoretical sites containing 500, 2,000, and 10,000 cubic yards of contaminated soil, respectively. The costs per ton were calculated as $300, $210, and $170 for each of the three sites, respectively. This unit cost included the estimates for remediation, site preparation, residuals shipping, handling, and disposal.