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I ' Appendix A - Site Background Information AGE-NC Project No 99-0624 ' Page 3 of 4 I analysis of grab water samples detected MTBE from CP 1-1 at depths of 60 feet and 76 feet bsg at concentrations of 88 lig/l and 1 6 �Lg/l,respectively, from CPT-2 at depths of 76 feet, 80 feet and 100 feet at concentrations as high as 49µg/l,and from CPT-3 at depths of 68 feet ' and 100 feet bsg at concentrations of 37 µg/1 and 4 3 µg/l, respectively MTBE was not detected in water samples collected from CPT-4 (Table 1) A report of findings (Cone Penetrometer Testing(CPT)Report-November 2001, dated 21 June 2002) was submitted ' by AGE to the SJCEHD July 2003 - Ground water monitoring wells MW-6 and MW-7 were installed at the site to ' depths of 65 feet bsg and 90 feet bsg, respectively, installation of off-site well (MW-5)was not conducted due to permitting issues TPH-g was detected in the 25-foot soil sample from MW-6 and the 50-foot soil sample from MW-7 at concentrations of 3 0 mg/kg and 12 mg/kg, respectively, MTBE was detected from MW-7 at depths between 50 feet and 90 feet bsg at concentrations as high as 28 mg/kg,respectively,TAME was detected in the 50-foot and 70- foot soil samples from MW-7 at concentrations of 0 11 mg/kg and 0 011 mg/kg,respectively, ' TBA was detected from MW-7 in the 50-foot soil sample at a concentration of 2 9 mg/kg Laboratory analysis of initial water samples collected from MW-7 detected MTBE at a concentration of 16 [ig/l A report of findings(Quarterly Report-Third Quarter 2003, dated 02 February 2004) was submitted by AGE to the SJCEHD ' Between November 1999 and September 2003, fourteen ground water monitoring events were performed at the site to monitor dissolved petroleum hydrocarbon concentrations in ground water and to characterize ground water flow direction and gradient on the site Generally, TPH-g was detected in water samples collected from wells MW-1, MW-2 and MW-3 at concentrations as high as 23,000 µg/l, BTEX compounds from wells MW-1 through MW-3 at concentrations as high as 1,700 [ig/l, and MTBE from wells MW-1, MW-2, MW-3 and MW-7 at concentrations as high as 19,000 pg/1 Based on the current area bound by wells MW-1 through MW-7, the lateral extent of the dissolved petroleum hydrocarbon plume is not known toward the south The vertical extent is marginally defined beneath the UST tank pit area(MW-7) and approximately 85 feet south (downgradient) of the former UST tank pit area(CPT-1) 5.0. REGIONAL GEOLOGIC SETTING According to a Geologic Map of California, published in 1966 by the California Department of Conservation Division of Mines and Geology,the site area is within the Great Valley Geomorphic Province(GVGP)of California, a large, elongate,northwest trending structural trough The GVGP . is subdivided into two mayor divisions designated the Sacramento and San Joaquin Valleys, which Advanced GeoEnvironmental,Inc