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c Jeffery g Won TreadvvelORollo San Joaquin County Environmental Division 22 December 2003 Page 2 PROPOSED WELL DESTRUCTION Eight wells are in an area with groundwater impacts, and shall be destroyed by drilling out the casings and pressure grouting the holes. Ten other wells are in areas without significant groundwater impacts, and shall be destroyed by pressure grouting the well casings. The area of the site with impacted groundwater is the former Tank No. 8 location located in the southern portion of the site (Figure 1). There are six monitoring wells and two groundwater extraction wells in this area(MW-19A, MW-19B, MW-20A, MW-20B, MW-21A, MW-21B, EW-1 and EW-2). These wells are in an area of confirmed or suspected groundwater impacts and the destruction method planned is to drill out the casings and pressure grout the holes. We request that destruction of these wells be approved by the SJCEHD because of the proposed site redevelopment. After site construction, wells in this area will be replaced as required by the SJCEHD. Well locations have been surveyed to allow well replacement as close as possible to original locations. An additional workplan for this site pertaining to potential groundwater remediation in this area is also being prepared. Table 1 identifies the eight wells proposed for destruction by drilling out. The other ten wells at the site are not located in areas of significant groundwater impacts and the destruction method planned for these wells is to pressure grout them in place. Table 1 identifies the ten wells proposed for destruction by pressure grouting (MW-1, MW-2, MW-4, MW-5, MW-8, MW-11, MW-12, MW-13, MW-18 and MW-25). These nine wells did not have any detectable petroleum hydrocarbons or volatile organic compounds (VOCs) in their most recent groundwater sampling, and have had either no or low, sporadic detections of petroleum hydrocarbons or VOCs for several years. Most of these wells are already on an annual sampling program. We request that destruction of these wells be approved by the SJCEHD because data from them demonstrates that they are not in areas of significant groundwater impacts. All soil, groundwater and decontamination water generated during well destruction will be stored on site pending analytical results. All borings will be destroyed in accordance with California well destruction guidelines and SJCEHD requirements, and well destruction permits will be obtained for all wells. SCHEDULE Above ground demolition(down to building foundations) is scheduled to begin during the third or fourth week of January 2004. The subsurface demolition is planned for March 2004. The subsurface demolition will involve removing all building foundations, subsurface utilities, and likely reworking the top 20 to 48-inches of the surface at the site. All wells will need to be destroyed prior to the subsurface demolition. We plan to destroy the ten monitoring wells in areas without significant groundwater impacts prior to 15 January 2003. We plan to keep the eight wells located around the former UST No 8