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' OEOMATRIX ' as soon as practical to provide consultation regarding the reuse or final disposition of the soil. Options for the possible reuse and disposal of oil-affected soil are outlined later in this docu- ment. This document is intended for distribution to ChevronTexaco,the property owners, future property developers, and construction contractors, and the appropriate regulatory agency. ' 2.0 BACKGROUND The subject environmental sites are located along Byron Road east of Corral Hollow and west ' of Grant Line Road in Tracy, California. Various developments have been initiated and/or completed on each of the subject parcels and current site use includes both residential and commercial uses. ChevronTexaco's predecessors, Standard Oil of California and Associated Pipeline Company, operated crude oil pipelines from the early 1900s through the mid-1960s that carried crude oil to refineries in the San Francisco Bay Area. The former pipelines were ' located within the right-of-way adjacent to Byron Road. The pipelines were likely located on both the north or south sides of Byron Road and reportedly have been removed. ' Previous environmental assessments performed at proposed developments in the vicinity of the ' project area have been conducted to evaluate the presence of petroleum hydrocarbons (i.e., degraded crude/Bunker C fuel oil) in the subsurface that may be associated with former crude oil pipeline operations. These assessments were performed on behalf of ChevronTexaco and others at subject sites. The results of these investigation activities have been summarized in various reports (e.g., site specific SNIPs or health risk assessments)prepared for each of the respective properties. Information regarding these reports may be obtained from ChevronTexaco or the respective regulatory agency upon request. A short summary of environmental conditions within the project area is provided in the following sections. 2.1 NATURE AND EXTENT OF PETROLEUM HYDROCARBONS IN SOIL ' Results of previous investigations indicate that the lateral extent of petroleum-affected soil at adjacent sites is primarily limited to the former pipeline right-of-way adjacent to Byron Road ' and the highest concentrations in soil are usually collocated with groundwater(depths of approximately 5 to 10 feet). Concentrations of total petroleum hydrocarbons typically range ' from less than 1000 milligrams per kilogram(mg/kg) to as high as 24,000 mg/kg. Significant concentrations of benzene, toluene, ethylbenzene, and xylenes are typically not associated with ' the residual crude oil. The residual crude oil may also contain low (less than 1 mg/kg) concen- trations of non-carcinogenic polyaromatic hydrocarbons (PAHs). The vertical extent of petroleum-affected soil is typically between 5 and 25 feet bgs in the vicinity of the project area. Soil affected by degraded crude/Bunker C fuel oil is typically ' I:\Doc_Safe\7000SW243.01 I\Rev WCOS SMP.dee 2