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� i <br /> i <br /> Treadwell&Wlo <br /> 1 8 California Highway Patrol--385 West Grant Line Road, and <br /> 9 Shell Station (7-11 Store) — 455 West Grant Line Road <br /> 1 <br /> Details and concerns regarding each of these sites are summarized in Table 1 and briefly <br /> 1 described in the following paragraphs Various figures and tables for the potential offsite source <br /> areas and associated groundwater flow maps are provided in Appendix El through E8 <br /> 1 <br /> Former Chevron Station - 575 West Grant Line Road In 1964 an unspecified number of fuel <br /> ' USTs were installed at the former Chevron Station The steel USTs were removed and replaced <br /> with fiberglass USTs in 1984 There is no documentation available as to the location, size, and <br /> type of steel USTs removed or information regarding an investigation or remediation The four <br /> fiberglass fuel and waste oil USTs, oil-water separator sump,product lanes, and two hoists were <br /> 1 removed from the Chevron Station in 1994 (Touchstone Developments, 1994a&b) <br /> Contaminated soil was detected and overexcavated following UST removal (Table 1) Chevron <br /> 1 has since conducted several investigations and installed seven shallow and two deep groundwater <br /> monitoring wells (Secor, 2001 & 2002) <br /> 1 <br /> The groundwater beneath the former Chevron Station is currently contaminated with gasoline, <br /> ' diesel, oil and grease As of 2002, some of the highest concentrations of gasoline and diesel <br /> occur at the northeast corner (MW-7) of the Chevron site (Appendix EI) The depth to <br /> ' groundwater vanes between 6 to 7 5 feet bgs and the groundwater flow direction is to the <br /> northwest with local variations to the north-northeast (Appendix E1) <br /> The lateral and vertical extent of the Chevron diesel and gasoline plume, has not been fully <br /> 1 defined Contaminated groundwater has migrated offsite and possibly commingled with other <br /> upgradient sources (i c , Former Mobil and Scotties) The former Chevron Station is <br /> documented to have contaminated the groundwater to the north and northeast as discussed later <br /> in this section for the Tracy Express Wash &Lube facility As required by the SJCEHD, an <br /> I ' ongoing Joint Groundwater Monitoring Program coordinates monitoring of water levels and <br /> i <br /> Site Assessment Report 8 21 May 2003 <br /> TREADWELL&ROLLO,INC. <br />