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2.0 SITE CONDITIONS AND EXISTING REMEDIATION SYSTEMS In 1994, a release from an underground pipeline running from a diesel fuel AST was discovered at the LFC Tracy facility. The fuel had been used to supply a backup boiler at the plant. The volume released is not known, but the AST was immediately decommissioned and the leaking fuel line was excavated and permanently removed along with several hundred cubic yards of impacted soils that were disposed off site. LFC contracted Kleinfelder and Associates (Kleinfelder) to perform a site characterization to determine the extent of impacts. A series of borings were advanced, and sampling results indicated the impacts were confined to a limited area on the plant site. As part of the Kleinfelder study, 15 groundwater monitoring wells and two groundwater extraction wells were installed in and around the LFC facility. Figure 1 shows the well locations. Subsequent groundwater sampling indicated that floating, free-phased diesel fuel (free product) was present in the central portion of the plant, near the location of the release. 2.1 Present Site Conditions Quarterly monitoring with semiannual reporting is required under the terms of Monitoring and Reporting Program (MRP) No. R5-2002-0837, dated February 20, 2003, agreed upon by LFC and the RWQCB. The last round of sampling was conducted in December 2004. Figure 1 shows the locations of site monitoring and recovery wells and Figure 2 shows the December 2004 potentiometric surface. Water level measurements used in the interpretation of the groundwater surface indicate that the free product and dissolved phase impacts near the initial release location (in the central part of the LFC facility) are effectively being contained by the existing remediation system. This is evidenced by the cone of depression, which shows effective capture in the central part of the site. In December 2004, free product was observed in two monitoring wells at the site, MW-3 and MW-4. Prior to initiation of pumping from well EW-2, in October 2002, measurable product had also been present in this well. Since October 2002, product thickness trends in wells MW-3 and MW-4, which had been decreasing, appear to be increasing, most likely in response to the change in size and location of the cone of depression. This increase indicates that the product is somewhat mobile and that it is probably migrating toward the recovery well (EW-2). In addition to floating hydrocarbons, dissolved phase diesel is also present in the groundwater system in upgradient and downgradient wells. The spatial distribution of diesel concentrations in groundwater samples collected at the site is shown in Figure 3. Potential sources of upgradient impacts include former bulk petroleum storage facilities and fuel dispensing stations that were located to the south of the LFC plant, as described in the Fourth Quarter 2003, First Quarter 2004 and Annual Groundwater Monitoring Report, dated March 31, 2004. Examinations of the GeoTrans 2