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' Of June 2003 • AGE-NC Project No 97-0301 ' Page 4 of 5 i ' • Ground water elevation generally decreased at the site an average 3 31 feet between the June 2002 and the December 2002 groundwater monitoring events The decrease inground water elevation is probably due to seasonal fluctuation • The ground water elevation at the site was generally only 2 to 3 feet above the screened intervals of wells MW-1 through MW-7, and should yield samples fully representative of shallow ground water conditions,however,the water level in well MW-5 was approximately 48 feet above the screen interval and yielded a sample more representative of deeper ground water conditions • The core of the dissolved petroleum hydrocarbon plume appears to be located in the area of wells MW-1 and MW-7 Analysis of ground water samples collected from MW-1 and MW-7 suggest the core of the plume is impacted by TPH-g, TPH-d, TPH-k, BTEX and 1,2-DCA ' • Substantial concentrations of dissolved TPH-mo have previously been detected in water samples collected from well MW-4 (screened 30 to 50 feet bsg) and from well MW-5 (screened 80 to 90 feet bsg), indicating that there is a limited area impacted with TPH-mo in the area assessed • BTE&X and 1,2-DCA concentrations in ground water samples MW-1 and MW-7 were substantially above their respective Maximum Contaminant Levels in drinking water um • Very low concentrations of MTBE,_"and TBA have been detected at MW-1 indicating ' that there is only a minor impact of these components • The vertical extent of dissolved petroleum hydrocarbons is not fully defined at the site, the ' lateral extent of the dissolved petroleum hydrocarbon plume is not fully defined toward the southeast, east and northeast of the current area bound by wells MW-1 through MW-7 5.0. RECOMMENDATIONS ' Based upon data collected during December 2002, AGE recommends Continued ground water monitoring utilizing wells MW-1 through MW-7 The next quarterly ' ground water monitoring event should be performed concurrently with the California Tank- Line Inc site (3105 South El Dorado Street) A Work Plan for installation of three multi-level wells was submitted to the SJCEHD on 09 April 2002 and approved by the SJCEHD by letter on 22 April 2002 Because two of the multi-level wells ' are proposed in San Joaquin County right-of-way, encroachment permits are necessary prior to scheduling field work AGE is in the process of obtaining a"Faithful Performance Bond" for each Advanced GeoEnveronmental,Inc