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r WASTE DISCHARGE REQUIREMENTS ORDER NO.R5-2004-0160 2 CONTIGROUP COMPANIES,INCORPORATED FRENCH CAMP GRAIN ELEVATOR ENHANCED REMEDIATION PILOT STUDY SAN JOAQUIN COUNTY PROPOSED REMEDIATION PROJECT 6. Based on review of other remedial technologies and case studies, the Discharger proposes a granular zero valent iron(GZVI) injection pilot study to reduce carbon tetrachloride and chloroform concentrations. This technology is well suited for slow moving groundwater plumes, such as is observed at the Site. The pilot study will evaluate the efficacy of the amount and spacing of the GZVI injections. The effectiveness of the pilot study will be determined by measuring the concentrations of carbon tetrachloride,chloroform, and breakdown products in perimeter monitoring wells. Groundwater monitoring of amendments,breakdown products, and byproducts will continue until concentrations return to baseline levels, which will conclude the pilot study. 7. GZVI is a strong reducing agent. Electrons released during GZVI oxidation reduce the chlorinated compounds whereby the chlorine atoms are replaced by hydrogen atoms. During the reductive dechlorination process, the carbon tetrachloride and chloroform act as electron acceptors. The hydrogen ion,which will affect pH, and chlorine are produced from the reductive dechlorination process. Case studies show that 70 percent of the carbon tetrachloride is expected to degrade to non-chlorinated end products (such as carbon dioxide) and 30 percent is expected to degrade to chloroform. The GZVI will further promote degradation of chloroform with about 60 percent expected to degrade to methylene chloride and about 40 percent expected to degrade to non-chlorinated end-products. The biological half-life of methylene chloride is about 10 days, so a buildup is not expected. The ultimate end products are carbon dioxide and chloride. 8. The Discharger will drill three borings, as shown on Attachment B,which is attached hereto and made part of this Order by reference,to about 85 feet bgs. The locations of the borings were determined based on groundwater flow direction and area with the highest concentrations of pollutants in the B water bearing zone. The pilot study is focusing on the B water bearing zone because the horizontal permeability is much greater than the vertical permeability so there should not be an influence on the C water bearing zone during the pilot study. Depths of injection will be about 77.5 feet bgs, 72.5 feet bgs, 67.5 feet bgs, and 62.5 feet bgs to create four iron fractures per boring. About 4 cubic meters of GZVI slurry will be injected into each fracture for a total of about 16 cubic meters per boring. The GZVI slurry consists of guar gum, which makes the slurry viscous and allows the GZVI to be suspended and pumped into the boring, cross-linker to make the slurry more viscous, and an enzyme breaker to reduce viscosity once the fracture is emplaced in the subsurface. Guar gum is a carbohydrate made up of carbon,hydrogen, and oxygen. The cross-linker,BX-1L, is made up of boric acid sodium salt and ethylene glycol. The enzyme breaker, LEB-H, is made up of sodium chloride. 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 exceed 4 cubic meters per fracture because the mass of GZVI injected is controlled by the amount that can be hydraulically fractured into the subsurface.