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GEOMq�-RIX <br /> • 2.0 BACKGROUND <br /> The Burns and Pombo properties are bounded to the south by West 1 I 1 Street, to the west by <br /> Corral Hollow Road and to the northeast by the UPRC ROW. Pipelines, operated by Chevron <br /> and Texaco from approximately the early 1900s to the mid-1960s, ran parallel to the <br /> northeastern edge of the Burns and Pombo properties (Figure 2). These pipelines, which <br /> carried crude oil and Bunker C oil, were buried at a depth of approximately 3 feet bgs. <br /> Soil and groundwater investigations were conducted at the Burns and Pombo properties in July <br /> and September 1999. Details regarding these soil and groundwater investigations are presented <br /> in the Geomatrix reports Soil and Groundwater Investigation Report and Human Health <br /> Screening Evaluation, Burns Property(San Joaquin County APN 232-170-05), 1881 Rustan <br /> Road, Tracy, California (January 2000) and Soil and Groundwater Investigation Report and <br /> Human Health Screening Evaluation, Pombo Property (San Joaquin County APN 232-170-07), <br /> 1755 West I1 th Street, Tracy, California (January 2000). The field investigation revealed <br /> limited amounts of petroleum hydrocarbons in subsurface soil primarily along the northeastern <br /> edge of the properties that front the UPRC ROW. <br /> • Total petroleum hydrocarbons (TPH) were reported at concentrations varying between 22 and <br /> 18,000 milligrams per kilogram (mg/kg) in 14 of 22 soil samples collected in 1999. Benzene, <br /> toluene, ethylbenzene, and xylenes were either not detected or were detected sporadically at <br /> low concentrations (up to 7.5 mg/kg). In these same borings, various combinations of eight <br /> polynuclear aromatic hydrocarbons (PAHs; acenaphthene, benzo(a)anthracene, chrysene, <br /> fluorene, fluoranthene, naphthalene, phenanthrene, and pyrene) were detected at individual <br /> concentrations up to 6.8 mg/kg. <br /> Figure 2 shows the sample locations and the location where oil-affected soil was encountered at <br /> the Burns and Pombo properties. The oil-affected soil was encountered between depths of <br /> approximately 6 and 19 feet bgs. The lateral distribution of petroleum hydrocarbons in soil <br /> appears to extend no more than 100 feet south of the northeastern property boundary on the <br /> Burns property. The Pombo property, which is triangular in shape, has two areas where <br /> petroleum hydrocarbons have been detected in soil; the first is located in the northwestern <br /> portion of the property and extends laterally approximately 140 feet south of the northeastern <br /> property boundary; the second is located in the eastern corner of the property and extends from <br /> the northern property boundary to the southern property boundary. <br /> • <br /> \\s0\deptdata\Doc_Safe\6000s\61 15.014\SMP.doc <br /> 2 <br />