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Sl.ell SITE INVESTIGATION WORK PLAN Section 1.0 Introduction Conestoga-Rovers&Associates (CRA) is submitting this Site Investigation Work Plan on behalf of Shell Oil Products US(Shell) in response to the Central Valley—Regional Water Quality Control Board (CV- RWQCB)October 28, 2013 letter(Appendix A) requesting a work plan for removal of contaminants in soil and delineation of crude oil constituents. Per our February 25, 2014 letter,this work plan is limited to delineation of crude oil constituents.A meeting within the first two weeks in April 2014 was proposed in our letter as a follow-up to our January 23,2014 meeting to collaborate further on the approaches for managing risks to receptors and groundwater quality and confer on the timeframe for submittal of a remedial action plan. The following sections present a brief summary of the site background,the proposed scope of work, and schedule. 1.1 Site Background The site is located within a farmed field and topographically slopes toward the northeast. Based on previous investigations, three water bearing zones(designated as zones A, B, and C) have been identified and are monitored. Zone Depth Depth to Groundwater Elevation Typical Groundwater Interval Groundwater Range(ft MSL) Flow Direction (fbg) Range (ft bgs) A 10 to 50 31.84 to 38.65 85.60 to 88.79 North-Northeast B 105 to 125 24.63 to 36.63 83.84 to 92.79 Northwest C 160 to 177 50.99 to 57.56 63.30 to 67.81 East ft bgs=feet below ground surface;ft MSL=feet relative to mean sea level Soils underlying the site consist of clays and silts and to a lesser extent,sands and gravels that have been deposited as alluvial fans. The Central Valley Crude Oil Pipelines carried crude oil from the Central Valley to the Bay Area. The pipelines are located in the western portion of the Central Valley and the subject site is located near Tracy,California. Shell operated two pipelines(8 inch and 10 inch diameter)that traversed the site, oriented in a northwest to-southeast direction through agricultural land. The current site boundaries encompass approximately 2 miles of former crude oil pipeline ROW located south of Highway 205 northwest of Hansen Road and north of Schulte Road(Figure 1). The area is primarily undeveloped agricultural land. However,the Cordes Ranch Specific Plan has been approved by the City of Tracy to allow development of the area for commercial, manufacturing,and distribution use (Figure 2). 080223(30) 1 CONESTOGA-ROVERS&ASSOCIATES