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West Clay Property - 3 - 26 July 2016
<br /> 639 West Clay Street
<br /> Stockton, San Joaquin County
<br /> included. Please assure that groundwater gradient maps and iso-concentrations contour
<br /> maps for each hydrogeologic unit are presented in all future monitoring reports, starting with
<br /> the third quarter 2016 monitoring report, due 15 November 2016.
<br /> 7. A sensitive receptor survey needs to be performed, and must identify the all surface water
<br /> bodies and water supply wells within 2,000 feet of the Site, and field verify any wells
<br /> identified within 1,000 feet of the Site. Therefore, by 15 September 2016, submit a
<br /> Sensitive Receptor Survey Report.
<br /> 8. Include a well construction details table in all future reports. The well construction table
<br /> should include total depth, screen interval, installation date, well diameter, and which
<br /> hydrogeologic unit the well monitors. Inclusion of this information will allow for more
<br /> expedient review by staff.
<br /> 9. In a letter dated 15 November 2012, San Joaquin County Environmental Health Department
<br /> staff directed the following sampling schedule:
<br /> • Semi-annual sampling from wells MW-1, MW-2, and MW-29.
<br /> • Annual sampling from wells MW-9, MW-11 B, MW-14B, MW-27, MW-28, and EW-2.
<br /> • Biennial sampling from well MW-10.
<br /> • Discontinue collecting depth-to-water, total depth measurements, and sampling MW-3,
<br /> MW-4, MW-5, MW-7, MW-8A, MW-813, MW-11A, MW-12A, MW-12B, MW-13A, MW-
<br /> 13B, MW-16 through MW-26, and EW-1.
<br /> • Annually collect total depth measurements for MW-1, MW-2, MW-9, MW-10, MW-11 B,
<br /> MW-14B, MW-27 through MW-29, and EW-2.
<br /> At this time Central valley Water Board staff request that during the next semi-annual
<br /> groundwater monitoring event, Third Quarter 2016, that groundwater samples be collected
<br /> from all site wells, and that all site wells be gauged for depth to water and total depth.
<br /> Groundwater samples should be analyzed for TPH-G, TPH-D, BTEX, MTBE, di-isopropyl
<br /> ether (DIPE), ethyl tert butyl ether (ETBE), TAME, tert butyl alcohol (TBA),
<br /> 1,2-dichloroethane (1,2-DCA), and naphthalene. Staff request the expanded sampling
<br /> event to obtain a current understanding of the lateral and vertical extent of petroleum
<br /> impacts.
<br /> Based on results of the Third Quarter 2016 sampling event, recommendations for a reduce
<br /> sampling program may be submitted and should be included in the Third Quarter 2016
<br /> Groundwater Monitoring Report due 15 November 2016.
<br /> In summary, Central Valley Water Board staff expect the following:
<br /> 1. By 30 August 2016, submit a Work Plan proposing a scope of work to complete vertical
<br /> delineation down-gradient of the source area.
<br /> 2. By 15 September 2016, submit results from a Sensitive Receptor Survey Report.
<br /> 3. By 15 November 2016, submit the Third Quarter 2016 Groundwater Monitoring Report.
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