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Request to Conduct Non-Purge Groundwater Sampling 3/17/09 <br /> TOC 171and 171 Page 1 of 1 <br /> 172 CVRWQCB Best California 7647 Pacific 9 700 MW-11R $4,232 <br /> #390652 Gas, Ltd. Avenue, Stockton, MW-12R <br /> CA 95207 <br /> Total $9,302 <br /> Prior to the implementation of the non-purge sampling method,Best proposes to conduct a comparison test to <br /> evaluate the appropriateness of non-purge sampling. At Best Station#171, on a specified sampling date and <br /> following well gauging of the entire site, wells TB-7 and EW-5S will be initially sampled without purging. <br /> The collected samples will be labeled with the well name and a "NP" identifier. Then, those wells will be <br /> purged along with the remaining site wells. The purged well samples collected will subsequently be labeled <br /> with the well name and a "P" identifier. Following receipt of laboratory analytical results, Best/ Best will <br /> evaluate and compare the non-purged and the purged concentrations from the selected wells. <br /> A comparison test will also be conducted at Best Station#172,using representative wells MW-11 R and MW- <br /> 12R. If comparative results appear to be in relative agreement,then the SJCSMU and Best will conclude that <br /> the non-purge method will provide representative water quality results for the compounds of concern,and our <br /> request for non-purge sampling for all wells over the entire site for future sampling events should be <br /> approved. The only contaminants of concern at the sites are gasoline petroleum hydrocarbons; there is no <br /> measurable NAPL existing in the wells; and the wells are screened across the water table. <br /> Best will notify you five days in advance of the sampling event and when the method testing will be <br /> scheduled. Best will implement these proposed modified sampling procedures for the sites referenced above <br /> upon approval from the SJCSMU. If you should have any questions or comments regarding this transmittal, <br /> please do not hesitate to contact the undersigned at (562) 921-3581. <br /> Sincerely, D 'FCr <br /> r <br /> No.55->97 <br /> Simon Tregurtha Larry Higinbotham OF Cf�L�F�Q, <br /> Project Manager Registered Geologist <br /> Chris Panaitescu <br /> General Manager <br /> Environmental Affairs <br /> cc: BP West Coast Products LLC; Ms. Janet J. Wager <br /> F;IP <br />