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Upgradient and Downgradient Groundwater Samples <br />In its 19 March 2018 letter requesting assessment of the LNAPL detection in LIF #4, Central <br />Valley Water Board staff requested soil and groundwater samples upgradient and downgradient <br />of LIF #4. In its April 2018 Work Plan, BNSF reasons that upgradient and downgradient <br />groundwater samples are not needed, because the corresponding 2017 LIF samples did not <br />contain hydrocarbon responses. However, while the LIF reveals LNAPL in soil micropores, it <br />does not reveal dissolved phase pollutants. Therefore, the LIF samples do not substitute for <br />upgradient and downgradient groundwater concentrations, and BNSF needs to provide these <br />groundwater samples. <br />BNSF may proceed to obtain upgradient and downgradient groundwater samples in this <br />mobilization, or in a subsequent mobilization. If it chooses to obtain them in this mobilization, it <br />should implement the following: <br />Provide a diagram illustrating where it proposes the upgradient and downgradient <br />sample points, and <br />Advance groundwater borings as described in this Work Plan. <br />If BNSF chooses to obtain groundwater samples in a subsequent mobilization, it should provide <br />the following: <br />1. A work plan to obtain upgradient and downgradient groundwater samples, which shall <br />be submitted with the Field Sampling Report describing the Work Plan results. <br />By 3 August 2018, please notify Central Valley Water Board staff when BNSF chooses to obtain <br />the groundwater samples. <br />Conditional Concurrence <br />Central Valley Water Board staff conditionally concur with the Work Plan provided BNSF <br />provide the following: <br />By 3 August 2018, commit to obtaining upgradient and downgradient groundwater <br />samples either in this mobilization, or in a subsequent mobilization. <br />Add analysis of TPH diesel without silica gel cleanup for soil and water samples. <br />Add analysis of VOCs by EPA Method 8260B to soil and groundwater samples. <br />Thank you for working with Central Valley Water Board staff to resolve the question of whether <br />remediation will be needed at the BNSF Mormon Yard. We look forward to seeing the Field <br />Sampling Report by 28 September 2018. <br />If you have any questions, you may contact me by email at Amy.Terrell@Waterboards.ca.gov or <br />by t4lephone t (916) 464-4680. <br />AMY/TERRELL, P.E. <br />Federal and Private Sites Cleanup Unit <br />cc: Mr. Michael Kith, San Joaquin County Environmental Health Dept., Stockton <br />Ms. Laura Kennedy, Kennedy/Jenks Consultants, San Francisco <br />Mr. Doug Brannan, Kennedy/Jenks Consultants, Whitefish MT (via email) <br />Mr. Mike Makerov 2 5 July 2018