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Vicki McCartney, REHS <br /> 10 December 2004 <br /> Page 2 MEMORANDUM <br /> l 4. Continuous soil cores will be collected from borings SB- 1 , SB-2 and SB-3 for <br /> logging purposes, and soil samples will be retained every five feet or at lithologic <br /> E changes for possible laboratory analyses. Up to 5 soil samples from each boring will <br /> be analyzed. <br /> Monitoring Well Sampling <br /> All four monitoring wells at the site will be sampled in accordance with San Joaquin County and <br /> Tri-regional Board LUFT Guidelines. Attached is a Standard Operating Procedi re for <br /> groundwater sampling that will be followed for the site. Blaintech Services Inc. will be <br /> conducting the sampling on 15 December, 2004. <br /> Laboratory Analyses <br /> 1 . Groundwater samples will be analyzed for TPH as kerosene (TPHk) by EPA Method <br /> 8015M, and TPH as gasoline (TPHg) , BTEX, fuel oxygenates, 1 ,2-DCA, and EDB, <br /> using EPA method 8260B. <br /> 2. Soil samples will be analyzed for TPHg, and BTEX and MTBE by EPA Method <br /> 8015M and EPA Method 8021, and TPHk by EPA Method 8015M. <br /> 3 . We do not propose to analyze for ethanol and methanol in groundwater, as it was not <br /> detected in our recent sampling, has never previously been detected at the site in <br /> groundwater, and there is no evidence that it has ever been used or stored at the site. <br /> 4. At your request we are analyzing the soil and groundwater samples for TPHk, <br /> however, it appears that previous TPHk detections do not represent the presence of <br /> TPHk, but appear to be carry-over from higher associated TPHg concentrations. The <br /> following data supports this conclusion: <br /> • TPHk has only been detected in the presence of TPHg, and in abnost all <br /> samples the TPHg concentrations are significantly higher than TPHk <br /> concentrations. <br /> • TPHk detections during the recent and previous sampling are consistently <br /> identified as not matching the TPHk standard. <br /> • There is no evidence that TPHk has ever been used or stored at the site. <br /> Please contact us with any questions or comments. <br /> V.'\Home1DAVIDV.597.11 Stockton gamge\2597 11 WP Addemdum.doc <br />