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BP #172 (Thrifty) - 5 - 9 March 2017 <br /> 7647 Pacific Avenue <br /> Stockton, San Joaquin County <br /> call-out boxes. In order to provide better visual representation of the distribution of <br /> dissolved phase contaminants, in future GMR submittals, please include chemical- <br /> specific iso-contours for TPHg, benzene, and MTBE in each of the established <br /> groundwater zones. The next GMR is to present second quarter 2017 groundwater <br /> monitoring and sampling data as is due 30 July 2017. <br /> 8. There are currently four (4) pairs of co-located shallow and deep monitoring wells: (1) <br /> MW-3 and MW-15, (2) MW-13 and MW-14, (3) MW-6 and MW-16, and (4) MW-17 and <br /> MW-20. In order to evaluate any possible vertical gradient at the Site, in the GMR due <br /> 30 July 2017, please include tabulated calculations of vertical gradient for each co- <br /> located well pair. . <br /> In summary, Central Valley Water Board staff request the following: <br /> • By 19 May 2017, please submit a Work Plan to include: <br /> o A proposal for the installation of a shallow well near MW-23 to delineate the <br /> extent of hydrocarbon impacts to shallow groundwater downgradient (northeast) <br /> of the Site. <br /> o A proposal for the installation of a monitoring well near existing well MW-23 to <br /> assess groundwater impact deeper than 75 feet. <br /> o A proposal for the collection of shallow soil in the vicinity of the former waste oil <br /> tank with analysis to include TPHg, VOCs, SVOCs, PAHs, PCBs, and Title 22 <br /> Metals. <br /> o A proposal for the collection of soil outside the hydrocarbon impacted area in <br /> order to establish background metals concentrations for comparison. <br /> • By 16 June 2017, please submit a Remedial Action Plan for implementation of full-scale <br /> SVE/AS remediation. <br /> • By 30 July 2017, please submit a Groundwater Monitoring Report which presents <br /> second quarter 2017 groundwater sampling data. Please include tabulated calculations <br /> of vertical gradient at the four (4) pairs of co-located shallow and deep Site wells. <br /> Please also include chemical-specific iso-contours for TPHg, benzene, and MTBE for <br /> each groundwater zone in all future GMRs. <br /> If you have any questions.or concerns regarding comments in this letter please contact the <br /> undersigned at (916) 464-4615 or by email at alan.buehler@waterboards.ca.gov. <br /> l <br /> Alan M. Buehler, P.G. <br /> Engineering Geologist <br /> cc: Sriram lyer, State Water Resources Control Board, Cleanup Fund, Sacramento <br /> Nuel Henderson, San Joaquin County Environmental Health Department, Stockton <br /> Jeanne Homsey, ATC, Modesto 95351 <br />