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' S E C ® R --- ' • Cleanup Plan October 27, 2003 ' Page 8 remedial action, estimated costs and project schedule for each remedial alternative, ' preferred alternative (groundwater oxygenation) and a work plan for additional site assessment activities (SECOR, 2003d). • On September 3, 2003, under the supervision of SECOR, Cascade completed 12 offsite soil ' borings (C-3.5, C-4.5, C-6, C-8, D-4, D-5, D-6, D-9, F-9, H-9, J-8, and K-8). Discrete soil samples and grab groundwater samples were collected from each location. The purpose of the offsite assessment was to further delineate petroleum hydrocarbons in groundwater and ' soil along the northeastern and northwestern site perimeter. The results and discussion of these activities were reported in the 2003 Offsite Assessment Report(SECOR, 2003f). ' On September 4, 2003, off-site groundwater monitoring wells (MW-53A, MW-57A, MW-58A, and MW-59A) were destroyed by Cascade. Monitoring wells were destroyed in accordance with SJC-EHD well standards for well destruction. The results and discussion of these ' activities will be reported in the upcoming Third Quarter 2003 Quarterly Groundwater Monitoring Report. 3.0 NATURE AND EXTENT OF CONTAMINATION Hydrocarbon compounds have been detected in the subsurface as a result of the five previously reported spills at the site. The results of investigations and actions related to these releases have ' been used to develop the following summary of the extent of fuel hydrocarbons in the subsurface. 3.1 Soil Contamination ' The highest petroleum hydrocarbon concentrations (TPHd, TPHg, and MtBE) detected in soil were 14,000, 3,700 and 7.6 milligrams per kilograms (mg/kg), respectively. These hydrocarbon ' compounds were detected in shallow soil located around the loading rack area and near Tank 137, the transmix tank. The location of these maximum concentrations appears to be consistent with the areas where previous spills have occurred. ' Previous investigations indicate that there are three main areas at the site where soil has been impacted by petroleum hydrocarbons: 1) the area northeast of the loading racks, 2) the area surrounding Tank 137, and 3) the area around the former Key Lock facility. The lateral extent of soil ' contamination appears to be limited to these general areas and does not appear to extend offsite. Concentrations of petroleum hydrocarbons in these areas appear to be the highest around the capillary fringe (between 3 to 8 feet bgs). However, detections of petroleum hydrocarbons have ' been reported as deep as approximately 29 feet bgs. The vertical extent of hydrocarbons in soil has been adequately defined. ' Historic soil concentration figures presenting hydrocarbon distribution in soil are presented in Attachments C. ' I:\Chevron\1001621\REPORTS\2003\2003-Cleanup Plan\Cleanup Plan.doc