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3 <br /> C A M B R I A <br /> In October 1990, Aegis installed wells MW-1, MW-2, and MW-3. Soil and groundwater <br /> samples collected from these well borings were ND for TPPH, and benzene, toluene, <br /> ethylbenzene, and xylenes (BTEX). This investigation is summarized in Aegis' <br /> March 26, 1991 Site Assessment/Monitoring Well Installation Results Report. <br /> In August 1995, Fugro West, Inc. of Roseville, California drilled boring B-17 and installed <br /> well MW-4. TPPH and BTEX were ND in soil samples collected from these borings. <br /> Site closure was granted by .the RWQCB in a letter dated July 18, 1996. On <br /> October 15, 1996, Enviros, Inc. (Enviros) destroyed wells MW-1 through MW-4 by pressure <br /> grouting. These activities are described in Enviros' November 19, 1996 Well Destruction <br /> Report. <br /> In January 1999, Triangle Construction of Sacramento, California removed the USTs, <br /> dispensers; and associated piping. Cambria observed the UST removals on January 19, 1999 <br /> and collected samples from the tank excavation bottom and from beneath the former <br /> dispensers, product piping, vapor recovery piping, and vent lines on January 22, 1999. Based <br /> on the analytical results from these soil samples, Cambria returned to the site on <br /> February 4, 1999 and conducted over-excavation in several locations. Soil samples were <br /> collected subsequent to.over-excavation. Soil sampling locations beneath the dispensers and <br /> product piping are shown on Plate 2. Complete results are presented in Cambria's <br /> June 11, 1999 Underground Storage Tank Removal Report. <br /> In February 1999, Stockton Service Station Equipment Company, Inc. of Stockton, <br /> California installed two new gasoline and diesel USTs and five dispensers in the same <br /> locations as the'formes USTs and dispensers. <br /> WORK PLAN <br /> Technical Rationale for Proposed Scope of Work. <br /> • The January 1999 UST removal identified several potential source areas of petroleum <br /> hydrocarbons and MTBE in soil beneath the site. <br /> • The vertical extent of petroleum .hydrocarbons and MTBE has not been delineated in <br /> some areas beneath dispensers and product.piping. <br /> 241-1346 2 <br /> I <br />