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Biwa <br /> FUGRO WEST, INC. C <br /> November 20, 1995 5855 Olivas Park Drive <br /> Pro ect No. 9347-1044 Ventura,Califomia 93003-7672 <br /> Tel: (805)650-7000 <br /> FAX: (805)650-7010 <br /> Mr. Mike Infuma <br /> San Joaquin County Environmental Health Division. <br /> 445 N. San Joaquin Street <br /> Stockton, California 95201 <br /> Subject: Exxon Service Station RAS # 7-0137 <br /> 1605 S. El Dorado Street <br /> Stockton, California <br /> Dear Mr. Infurna: <br /> No.- <br /> As you requested, please find attached a copy of the pilot test data that was included in <br /> the November 1993, Remedial Action Plan (RAP) for the subject site and documentation <br /> regarding the public notification process completed during air permitting. I have also included <br /> a copy of the remedial design constructed at this site. The following paragraphs discuss the <br /> rationale for the current remedial approach. <br /> The RAP proposed vapor extraction using a thermal/catalytic oxidizer. In a letter dated <br /> August 15, 1994, to the San Joaquin County Environmental Health Division (SJCEHD), Fugro <br /> proposed initiating remediation with a revised approach which would not require air emission <br /> control equipment. Fugro proposed low flow bioventing and ground water oxygenation. Air <br /> emission control is not required by the San Joaquin Valley Unified Air Pollution Control District <br /> (SJVUAPCD) for sources emitting less than 2 pounds of petroleum hydrocarbons per day. <br /> The data collected during the pilot test (see attachment A) indicated the petroleum <br /> hydrocarbon extraction rates were 7.6 and 40 pounds per day while extracting from VEW-1 and <br /> VEW-2. Based on this data, the bioventing system would need to operate on a timer for only <br /> short periods during each day to remain within the 2 pounds per day emission limit. <br /> Subsequently, it was decided to expedite the remediation by using higher flow rates which will <br /> result in higher petroleum hydrocarbon extraction rates to augment in-situ biodegradation. <br /> The higher petroleum hydrocarbon extraction rate can be treated efficiently by oxidation, <br /> however,the petroleum hydrocarbon extraction rate will decrease as the site is remediated. When <br /> suitable, granular activated carbon adsorption may be used for emission control. Both oxidation <br /> and GAC emission control methods have been permitted by the SJVUAPCD. Depending on how <br /> quickly the petroleum hydrocarbon extraction rate declines, Fugro may recommend operating the <br /> oxidizer until direct discharge without emission control would be allowed. <br /> 9347-1044.ylt <br /> A member of the Fugro group of companies with offices throughout the world <br />