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I <br /> i� <br /> GEOMATRIX <br /> BACKGROUND <br /> The area of the Dividend property addressed b this plan(the"project area")is located adjacent to <br /> P p rtY Y <br /> the Southern Pacific Railroad right-of-way(SP ROW). Crude oil pipelines, operated by Chevron <br /> and Texaco from approximately the early 1900s to the 1950s,ran parallel to the southern edge of <br /> the Dividend property along West Byron Road(Figure 2). The pipelines were buried at a depth of <br /> approximately 3 feet below ground surface. <br /> L <br /> Since 1989, soil and groundwater investigations have been conducted at the Dividend property and <br /> adjoining SP ROW on behalf of the Dividend Development Company, Texaco, and Chevron. The <br /> investigations have been reviewed by the PHS-EHD and the RWQCB. The results of these <br /> Linvestigations indicate that petroleum hydrocarbons characterized as degraded crude oil or Bunker <br /> C oil are present in subsurface soil along the southern edge of the property that fronts the SP ROW <br /> Land within the SP ROW, apparently the result of releases from the pipelines. The approximate <br /> locations of known crude/Bunker C oil affected soil on the Dividend property are shown on <br /> Figure 2. <br /> The petroleum hydrocarbons have been reported to be present in soil at concentrations up to <br /> 24,000 parts per million (ppm)between the depths of 5 and 16 feet within the SP ROW, and up <br /> to 7500 ppm on the Dividend property. This vertical distribution is likely the result of a <br /> fluctuating water table. The lateral distribution of petroleum hydrocarbons in soil is limited, and <br /> does not appear to extend more than 100 feet northeast of the SP ROW beneath the Dividend <br /> i <br /> property. <br /> The subsurface soil at the project area is predominantly silt and clay, with isolated sandy lenses, <br /> to a depth of at least 20 feet. The water table is about 7 feet below ground surface. Based on the <br /> groundwater investigations performed to date, shallow groundwater beneath the site has not been <br /> significantly affected by the degraded crude/Bunker C oil. In their 11 October 1996 letter <br /> (attached), the RWQCB has determined that the degraded crude oil is not a threat to groundwater <br /> quality and no further investigation, remedial or removal action, or monitoring is required. It <br /> C2677\SOILPLAN.DOC 2 <br />