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1 <br /> Corrective Action Plan <br /> 5.2 Treatment of Extracted Soil Vapor <br /> ' Emission of extracted and treated soil vapor at this site will be permitted by the San Joaquin <br /> Valley United Air Pollution Control District(SJVUAPCD). The hydrocarbon concentrations in <br /> ' the extracted soil vapor must be reduced to meet SJVUAPCD's site-specific standards. GAC is <br /> recommended for the treatment of extracted soil vapor both on the basis of its proven reliability <br /> and its cost. At this site, the total amount of hydrocarbons in the soil can be estimated with a <br /> ' reasonable degree of certainty. It is apparent that for the SVE process, several GAC change-outs <br /> will be required over the duration of the remediation project. As much as 25,000 lbs of GAC <br /> may have to be expended to treat the extracted soil vapor. At present prices,however, the costs <br /> ' for replacement and regeneration of the spent carbon will far more than off-set the much higher <br /> initial cost for a thermal/catalytic oxidizing unit, additional costs for auxiliary fuel, and the <br /> considerably higher costs of maintenance. <br /> ' The capacity of the proposed SVE extractions stem is 100 standard cubic feet per minute scfm <br /> y p ( ) <br /> at a vacuum of 12 inches of mercury. The treatment system will consist of two 1,000-1b canisters <br /> ' of vapor-phase GAC which are capable of accommodating more than 500 scfm. <br /> ' Major System Components: <br /> Four SVE/Groundwater Extraction Wells <br /> Soil Vapor Transport Piping <br /> 100-scfm Positive Displacement Vacuum Extraction Pump <br /> Moisture Knockout Device with Automatic Water Discharge <br /> ' Two 1,000-1b Vapor-Phase GAC Canisters <br /> 5.3 Treatment of Extracted Groundwater <br /> Extracted groundwater must be treated to remove petroleum contaminants prior to discharge to <br /> the surface drainage under an National Pollutant Discharge Elimination System (NPDES)permit <br /> or to the sanitary sewer system under a permit from the City of Manteca Public Works <br /> Department. The proposed groundwater treatment system is designed to meet the most stringent <br /> requirements from either permitting agency. <br /> ' Not onlyis GAC presently the most cost-effective and reliable <br /> p Y groundwater treatment method for <br /> ' this site, GAC adsorption offers the greatest flexibility for treating varying rates of groundwater <br /> production and can, therefore, accommodate any remaining hydrogeologic uncertainties. OST <br /> proposes to use two 1,000-1b canisters of aqueous-phase GAC to treat the water preceded by a <br /> . .' bag filter to remove particulate matter. Groundwater will be pumped from the four co-extraction <br /> wells using 5-gallon-per-minute (gpm) electric turbine pumps designed to provide automatic <br /> groundwater table drawdown control. <br /> t <br /> ' 701 1-2.cap OST <br /> Page 11 <br /> i <br />