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4 � <br /> GEQMATRIX <br /> BACKGROUND <br /> The area of the Nicholaw property addressed by this plan(the"project area") is located adjacent <br /> to West Byron Road. Pipelines, operated by CPL and other oil companies from approximately <br /> the early 1900s to the late 1950s,ran parallel to the northern edge of the Nicholaw property along <br /> West Byron Road(Figure 2). These pipelines carried crude oil and Bunker.C oil and were buried <br /> at a depth of approximately 3 feet below ground surface(bgs},. <br /> .Since 1990, soil and groundwater investigations have been conducted at the Nicholaw property on <br /> behalf of CPL. The investigations have been reviewed by the PHS-EHD. The results of these <br /> investigations indicate that limited amounts of petroleum hydrocarbons are present in subsurface <br /> soil along the northern edge of the property that fronts West Byron Road, apparently the result.of <br /> releases from the pipelines. .The petroleum hydrocarbons appear similar to those found at <br /> t <br /> j properties located directly across Byron.Hwy. (the Dividend,.San Joaquin County APNs 238-02- <br /> 10113/14), north of the Nicholaw parcel. The petroleum is likely degraded crude oil or <br /> Bunker C. <br /> Total petroleum hydrocarbons (TPH) have been reported to be present in soil in 1 of 16 soil <br /> samples collected in 1994, at a concentration of 2700 parts per million(ppm). Xylenes have <br /> been detected at concentrations up to 0.23 mg/kg in 8 of 16soil samples collected in 1994. The <br /> affected soil occurs between the depths of approximately 1 to 5.5 feet bgs. The lateral <br /> distribution of petroleum hydrocarbons in soil is limited.and does not appear to extend more than <br /> 50 feet southeast of the property boundary. The sample location where TPH-affected soil on the <br /> Nicholaw property was encountered is shown on Figure 2. <br /> The subsurface soil-at the project area is predominantly sift and clay;with isolated sandy lenses,.. <br /> to a depth of at least 20 feet. The water table is approximately 7 to 9 feet bgs. Based on the <br /> groundwater investigations performed to date, shallow groundwater beneath the site has not been <br /> affected.by the degraded crude oil. It has been determined by the PHS-EHD that the degraded <br /> crude oil is not a threat to groundwater quality. It should be noted that shallow groundwater <br /> IAWPD0CS\C3499WIC110SMP.D0C 2 <br /> I <br />