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11-07-1996 1 : 12PM FROM P- = <br /> en virus, <br /> October 10, 1996 <br /> Ms. Mary Meays <br /> San Joaquin County Public Health Services <br /> P.O. Box 388 <br /> Stockton,California 95201-0388 <br /> RE: Shell Service Station <br /> 2575 Country Club Blvd. <br /> Stockton,California <br /> WIC 204-7525-3505 <br /> Dear Ms. Meays: <br /> This letter is prepared in response to San Joaquin County Public Health Services <br /> (SJCPHS)correspondences dated September 12, 1996. <br /> Comments on July 30, 1996 Sampling Event <br /> Shell's ground water sampling contractor,Blaine Technical Services, includes inspection <br /> of the wellhead conditions as part of each sampling event and generally notes any <br /> deficiencies on their reports. The problems noted in your letter have been brought to <br /> Blaine's attention,and the requirements for wellhead maintenance have been reviewed with <br /> them. The specific items mentioned regarding this site will be repaired. <br /> Depth to Water Measurements <br /> Depth to water is measured and recorded on the field data sheets prior to purging activities. <br /> Shell's protocol for ground water sampling calls for wells to be recharged to 80% of their <br /> static levels after purging,prior to sampling. This is consistent with LTJFT Manual and <br /> SJCPHS guidelines. Typically,wells in this area do not de-water and recharge sufficiently <br /> to meet this sampling protocol immediately after purging. In response to your request,we <br /> propose to measure and record the depth to water immediately following purging activities <br /> during fourth quarter sampling events. Any wells which do not achieve adequate recharge <br /> immediately will be noted and checked again during subsequent sampling events. For <br /> wells which do not pose a problem,collection and recording of post-purge water levels will <br /> be a one-time event. <br /> MTBE Analysis <br /> Methyl tertiary-butyl ether(MTBE)has been detected in several wells onsite by EPA <br /> Method 8260. Following the recommendations of the State Water Resources Control <br /> Board memo of August 22. 1996,confirmation of the highest MTBE concentration <br /> detected by EPA Method 8020 was confirmed by EPA Method 8260. In this case, the <br /> highest concentration was detected in the duplicate sample for RW-1. The 8260 analysis <br /> confirmed the presence of MTBE. <br /> Subsequent sampling events will continue to include MTBE analysis by EPA Method <br /> 8020. <br /> !nv/ros. /nes 270 PeIAMS Sheet $mmm,+. C31,10,nq Tel 70"9JS-+ 50 <br /> P a !os 259 95J.`t'-0_50 rvX .07. 935-Sb/9 <br />