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• Performance of a vapor extraction pilot test over a 6-hour period in January 1992 Confirmation soil sampling after tank removal revealed that soil excavation activities had effectively removed petroleum impacted soil above a concentration of 29 mg/kg in the vicinity of the former tanks 2 2 Potential Receptor and Water Well Surveys A sensitive receptor survey was conducted to identify surrounding facilities or environmental features that may be affected by or may have an effect on subsurface conditions at the site In January 1998, Ahsto conducted a visual reconnaissance of the structures in the vicinity of the site and did not observe any apparent basements or subways within a 300-foot radius of the former BP Oil site Adjacent to and west of the site and across Elmwood Way and Pershing Avenue north and east of the site are residential properties Across Pershing Avenue and County Club Boulevard are commercial properties A survey of water wells within a 2000-foot radius of the site was conducted using files of the State of California Department of Water Resources (DWR) The survey identified two wells within the search radius as follows Well Designation Distance from Site Direction Well Use Well Status . from Site 2N/6E-33Q1 Approx 1800 ft Northwest Production Abandoned 2N/6E-33Q Appmx 1800 ft Northwest Production Abandoned The results of the well survey are included in Appendix A, and the completed potential receptor survey form is included as Appendix B 2 3 Site Geology and Hydrology Soil types encountered in the borings consisted of silty clay to clayey silt to depths of between approximately 13 and 22 feet, which was underlain by a layer of clayey to silty sand with a thickness of 4 to 5 feet Below the sand layer, silty clay to clayey silt was encountered to the extent of the borings at 30 feet with the exception of Boring MW-6,where silty sand was encountered to the total depth of the boring at approximately 40 feet The boring logs and well completion diagrams for the wells are included in Appendix C Hydrogeologic cross sections generated using the boring logs are shown as Figures 5 and 6 Groundwater flow characteristics have been interpreted from the groundwater elevation data from Wells MW-1 through MW-4 since May 1990, and MW-5 through MW-7 since August 1991 The groundwater gradient has been consistently in a northerly to northeasterly direction with magnitudes ranging from 0 003 to 0 04 The potentiometric groundwater elevations as interpreted from the results of the January 16, 2001 monitoring event are shown on Figure 7 The results of groundwater monitoring at the site are summarized in Table 2 RON, F\00\10-037\close doc 3