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• Work Plan—Byron Road,Tracy,California June 16,2003 06-6102-00-2931-030 Page 9 Current Project Activity The Westside Channel Outfall project has been underway since May 27, 2003. The trench excavation has progressed approximately 4,000 linear feet as of June 12,2003. During excavation activities the trench is logged by SAIC and photo-documented to record lithology and affected versus non-affected soils. On May 30, 2003, three test pits were excavated in the vicinity of dewatering wells 63 (test pit 3), 74(test pit 2), and 76 (test pit 1) to determine the extent of free phase oil observed in these wells. Test pits were completed by backhoe to a depth of approximately 12 feet bgs. Affected soil was observed in all three test pits. However, in test pit 1, affected soil was observed to a depth of 11 feet bgs. Test pits 2 and 3 contained visually affected soil to total.depth. SAIC logged the test pits and collected soil samples at the base of each test pit. Two samples were submitted for analyses of TPHc, BTEX,PAH's, CAM 17 metals, and pH. The third sample was submitted to ChevronTexaco Energy Research and Technology Companv (CTERTC) for fingerprinting. Extractable petroleum hydrocarbons quantified as motor oil and crude oil were detected in samples collected from TP-1 and TP-2 at concentrations of 2.9 and 3,000 mg/kg, respectively. The nature of the hydrocarbon within the soil matrix of TP-3 was determined to be a biodegraded,very light crude oil with approximate concentrations of 5800 mg/kg. Currently, Geomatrix Consultants, on behalf of ChevronTexaco is constructing a cross section of the Byron Road corridor with information provided from the dewatering wells logs. SCOPE OF WORK To characterize the nature and extent of contaminants along the 7,000-foot corridor, SAIC proposes the following scope of work: A records review and data summary(Task 1)and a conceptual site model(Task 2), will be compiled into a Soil and Groundwater Investigation Work Plan (Task 3). In accordance with the Consistent Technical Approach (CTA) (Second Draft Revised Technical Approach to Site Evaluation and Decision Making, Old Valley Pipeline Sites—Central Valley Region, dated December 18, 2002), the work plan will be prepared to characterize the lateral and vertical extent of petroleum contamination beneath the study area. The tasks presented below are a phased approach to identifying data gaps and areas of immediate concern prior to conducting field investigations. Task 1: Records Review and Data Summary Aeencv Database& Historic Map Review A search of environmental regulatory databases will be conducted on the study area. SAIC will contact Environmental Data Resources, Inc. (EDR) and order a Database Report of the Byron Road corridor. SAIC will review this report and identify and summarize all sites listed in the EDR database within one- half mile of the centerline of the study area. Additional research is likely to include a review of the City of Tracy directories to obtain available information on past and present operations or uses of sites indicating recognized environmental conditions. This information will be summarized and tabulated. SAIC will also obtain available aerial photographs along the study area corridor. The photographs will be reviewed and the site development summarized in the data summary report: Copies of the aerial photos will be included in the appendix of the report. Given the location and historical uses of the study area,we do not anticipate extensive Sanbom Fire Insurance Map coverage;therefore, SAIC will not review. K:CVX-O VP\ROW—STIES\westsidechannel\draftworkplan.doc