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Mr. Mike Makerov - 2 - 23 April 2015 <br /> highest fuel concentrations were found in the 2011 sample event. We agreed that the two <br /> October 2011 confirmation samples that contained lower amounts of petroleum compounds <br /> (110 and 150 mg/kg) are likely to be representative of ambient railyard concentrations, <br /> therefore, a background boring will not be required at this time. <br /> A public water supply well is located on the north side of the railyard, therefore Central Valley <br /> Water Board staff request that BNSF obtain grab groundwater samples beneath the spill site <br /> during this assessment. In view of the previous confirmation sample results, Central Valley <br /> Water Board staff will accept two soil borings located where the inner two borings are proposed, <br /> and BNSF should obtain samples at depths of 5, 10, 15, 20, and 30 feet below ground surface, <br /> and obtain a groundwater sample from each boring. BNSF may hold the 20 and 30 foot <br /> samples and should analyze them if the overlying 15 foot sample contains detectable amounts <br /> of petroleum. <br /> Central Valley Water Board staff conditionally concur with the Work Plan provided BNSF <br /> incorporate the following changes and additions to the Work Plan. <br /> 1) Two soil borings shall be advanced to groundwater within the former spill zone. In <br /> addition to obtaining samples from 5, 10 and 15 feet bgs, soil samples shall also be <br /> obtained from 20 and 30 feet bgs and a groundwater sample shall be obtained from <br /> each boring. <br /> 2) Soil samples shall be analysed for TPHd without silica gel cleanup. <br /> 3) Soil samples from 20 and 30 foot bgs shall be analyzed for TPHd if the 15 foot sample <br /> from that boring shows detectable amounts of TPHd. <br /> 4) Groundwater samples shall be filtered and analyzed for TPHd without silica gel cleanup. <br /> BNSF anticipates implementing the work plan in May 2015 and providing a Site Assessment <br /> Report about 4 to 6 weeks thereafter. Therefore, please provide the Site Assessment Report <br /> by 26 June 2015. <br /> Central Valley Water Board staff appreciate the rapid response of BNSF after the release, and <br /> for following through with the post-confirmation sampling. If you have any questions, you may <br /> cont ct me y email at Amy.Terrell@Waterboards.ca.gov or by telephone at (916) 464-4680. <br /> AM TERRELL, P.E. <br /> Federal and Private Sites Cleanup Unit. <br /> cc: Mr. Muniappa'Naidu, San Joaquin County Environmental Health Dept., Stockton <br /> Ms. Laura Kennedy, Kennedy/Jenks Consultants, San Francisco <br />