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AWAWAM <br /> . Working to Restore Nature <br /> 1710 Main Street <br /> Escalon, CA 95320OCT I <br /> Phone (209)838-3507 <br /> FAX (209)838-3509 E.R\1I^Ql1I 1 l 1TAJ HF(1I TH October 8, 1992 <br /> PERM11 <br /> Mark Schonhoff <br /> San Joaquin Valley Unified Air Pollution Control District <br /> 2321 W Washington St , Suite I <br /> Stockton, California 95203 <br /> RE: C M. Weber Enterprises, Inc , Property <br /> 141 North El Dorado St , Stockton <br /> UAPCD Permit Nos AP 91-467 and AP 92-111 <br /> Dear Mr Schonhoff <br /> This report summarizes the performance of the Vapor Extraction System located at the above <br /> referenced site (Figure 1) The vapor extraction system induces a vacuum in the subsurface via <br /> extraction wells which are screened from 5 feet below grade to 1-2 feet above the water table. <br /> The induced subsurface vacuum increases the rate at which gasoline will volatilize making <br /> extraction of the contaminants feasible <br /> An internal combustion engine operated at the site from the end of January through mid-March, <br /> 1992 It was replaced during the week of March 16, 1992, with a 250 standard cubic feet per <br /> minute (SCFM) thermal oxidizer (ORS Environmental Equipment Model ORS798001) The <br /> thermal oxidizer operated from March 31 to July 13, 1992 Performance logs for the thermal <br /> oxidizer during this period are presented in Attachment 1 A Granulated Activated Carbon <br /> (GAC) system replaced the thermal oxidizer on July 21, 1992 and became operational on July <br /> 30 Due to a mechanical problem, the system was not functioning between September 3 and <br /> September 23 It was restarted on September 24 and continues to operate <br /> The GAC system consists of one 5 horsepower regenerative blower and two 2000 pound <br /> granulated activated carbon vessels arranged for series operation The carbon vessels act as the <br /> off gas treatment technology from the vapor extraction wells Unlike the thermal oxidizer, the <br /> carbon vessels remove and store the contaminants present in the well vapor Once a carbon <br /> vessel has been "loaded" to a certain point with contaminants, it must be removed for <br /> regeneration The carbon in the GAC system can be loaded to approximately 10-20% of its <br /> weight Each of these vessels can remove approximately 300 pounds of contaminants It is <br /> estimated that 213 pounds of total petroleum hydrocarbons as gasoline (TPHG) has been retained <br /> within the canisters since operation began Table I presents an estimate of the amounts of <br /> VEP MRM <br />