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INFORMATION SHEET WASTE DISCHARGE REQUIREMENTS ORDER NO.R5-2004-0160 CONTIGROUP COMPANIES,INC. FRENCH CAMP GRAIN ELEVATOR ENHANCED REMEDIATION PILOT STUDY SAN JOAQUIN COUNTY ContiGroup Companies,Inc. (Discharger) formerly owned the active grain storage and transfer facility at 9504 South Harlan Road in French Camp (Site). Historically,liquid fumigants containing carbon tetrachloride were stored on site in five-gallon buckets. Carbon tetrachloride was found in groundwater in 1999. Several investigations have been conducted to delineate the extent of carbon tetrachloride and its breakdown product, chloroform. Three water bearing zones are identified at the Site with most of the mass of pollution in the B water bearing zone. The B water bearing zone is about 60 to 80 feet below ground surface(bgs) axed varies from about 5 to 15 feet thick across the Site. The Discharger proposes a nine-month granular zero valent iron(GZVI)injection pilot study to reduce carbon tetrachloride and chloroform concentrations. GZVI is a strong reducing agent. Electrons released during GZVI oxidation reduce the chlorinated compound whereby the chlorine atoms are replaced by hydrogen atoms. During the reductive dechlorination process, the R carbon tetrachloride and chloroform act as electron acceptors. The purpose of the pilot study is to reduce pollutant concentrations and evaluate GZVI as a remedial alternative. Under reductive dechlorination,carbon tetrachloride and its breakdown product chloroform are reduced to methylene chloride. As the groundwater moves out of the area of the GZVI into aerobic conditions,the methylene chloride breaks down with the ultimate end products of carbon dioxide and chloride. The Discharger will drill three borings to about 85 feet bgs. Points of injection will be spaced at about 77.5 feet bgs, 72.5 feet bgs, 67.5 feet bgs, and 62.5 feet bgs to create four iron layers per boring. About 4 cubic meters of GZVI slung will be injected into each layer for a total of about 16 cubic meters per boring. The GZVI slung consists of guar gum,which makes the slurry viscous and allows the GZVI to be suspended and pumped in to the boring, cross-linker to make the slurry more viscous, and an enzyme breaker to reduce viscosity once the layer is emplaced in the subsurface. The mixture of slurry is 400 kilograms of iron, eight kilograms of guar gum,three quarters to two liters of cross-linker, and 0.02 liters of enzyme breaker per cubic meter of slurry. The amount injected may be less,but not more than 4 cubic meters per layer because the mass of GZVI injected is controlled by the amount that can be hydraulically fractured into the subsurface. The WDRs require extensive monitoring to evaluate the effects of the proposed injections. When the pilot study is completed,the amendments and byproducts shall not exceed baseline levels. DLL 9/14/04