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Removal of Product-Delivery lines November 5, 1990 <br /> Former Exxon Station No. 7-1050, Stockton, California AGS 30045-1 <br /> As soil was removed from above and below the underground product-delivery lines, the <br /> geologist evaluated soil for hydrocarbon vapor concentrations using a photoionization <br /> �r <br /> detector (PID). <br /> Field instruments such as the PID are useful for indicating relative levels of hydrocarbon <br /> vapors, but do not detect the concentration of hydrocarbons present with the same precision <br /> as laboratory analysis. Our geologist did not detect positive readings on the PID. Soil <br /> excavated from beneath the lines was stockpiled onsite and covered with plastic sheeting <br /> pending laboratory results. <br /> Soil samples were collected by driving a hand-operated percussion sampler fitted with a <br /> clean brass sleeve into the native soil at the base of the trench. The sleeve was removed <br /> from the sampler and sealed promptly with aluminum foil, plastic caps, and tape. The <br /> sample was then labeled and placed in iced storage. Chain of Custody Records were <br /> initiated by the geologist in the field and accompanied the samples to the analytical <br /> laboratory. Copies of these records and the laboratory reports are included in Appendix A. <br /> 5 <br /> Applied GeoSystems <br />