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AM B R I A Ms Vicki McCartney April 6,2006 analytical data collected from bonngs CPT-6 through CPT-8 define the lateral extent of petroleum hydrocarbons to the west, southwest, and south of the source area Groundwater samples from the CPT-9 through CPT-11 contained primarily TPHg and benzene and, to a lesser extent, MTBE The highest concentrations of gasoline constituents were detected at depths ranging from 65 to 73 fbg The highest TPHg and benzene concentrations were detected east of the former USTs in boring CPT-11 at 65 fbg Cambria's January 21, 2003 Site Investigation Report describes this investigation 2004 Site Conceptual Model- On October 7, 2004, Cambria submitted a Site Conceptual Model which summarizes previous activities and recommends additional CPT bonngs Groundwater Monitoring Program Nine on-site groundwater monitoring wells (MW-1 through MW-9) and one off-site well (MW-10) are currently associated with the site Although there is } some variation, the groundwater flow beneath the site is predominantly north to northeast, and there is often a hydraulic mound near well MW-2 During the fourth quarter 2005, TPHg was detected in wells MW-2, MW-4, MW-7, and MW-9 at concentrations ranging between 78 ppb (in MW-4) to 2,300 ppb (in MW-9) Wells MW-2 and MW-9 contained 7 7 and 44 ppb benzene, respectively Wells MW-2,MW-4, MW-8, and MW-9 contained MTBE from 4 0 ppb(in MW-2) to 3,400 ppb (in MW-8)rand tertiary-butanol (TBA) from 7 2 ppb (in MW-4)y to 1,600 ppb (in MW-8) Wells MW-1, MW-3, MW-5, and MW-6 were not sampled during the fourth quarter 2005 Wells MW-2, MW-7,MW-8, and MW-9 are sampled quarterly Wells MW-4 and MW-10 are sampled semi-annually during the second and fourth quarters Wells MW-1, MW-3, MW-5, and MW-6 are sampled annually during the second quarter A complete summary of the fourth quarter 2005 groundwater sample results can be found in Cambria's January 10, 2006 Fourth Quarter 2005 Groundwater Monitoring Report Remediation Summary An SVE system operated at this site from September 1992 to November 1996 During this time, the SVE system removed approximately 17,628 pounds of vapor-phase TPHg from the subsurface Based on the quarterly monitoring groundwater analytical results and previous CPT investigation data, SJCEHD requested further investigation of the extent of petroleum constituents and fuel oxygenates in soil and groundwater beneath the site Cambria submitted the requested work plan on August 31, 2005 and presents the results of this work below 3