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J. H. KLEINFELDER & ASSOCIATES File: 24-2038-1/28:725 ` December 10, 1986 Page 3 equipment was cleaned with a trisodium phosphate wash and a distilled water rinse prior to collecting subsequent samples. 5.2 Soil Sampling Procedures .. Soil samples were collected for chemical analysis and to obtain an accurate lithologic log. Samples were collected at five foot intervals starting at a depth of five feet below the ground surface. The specified sampling locations are shown on Plate Nos. 4 and 5. Soil samples were collected by advancing the boring to a point immediately above the sampling depth and then driving a Modified California Sampler lined with three brass tubes into the undisturbed soil. The sampler was then removed from the bottom of the boring and the bottom (third) tube sealed with aluminum foil and tight fitting plastic ` caps. The sealed tube was immediately stored in an iced cooler. At the end of drilling operations, select soil samples were delivered under chain—o£—custody to California Analytical Laboratories/ENSECO in West Sacramento, California. The analytical results and a completed copy of the chain—of—custody form are included in Appendix B of this report. The remaining soil samples were retained in refrigerated storage for future reference or analysis. 5.3 Oualitative Field Screening A Photovac TIP using a photoionization detector (PID) was used to screen each soil sample collected from borings MW-1 and MW-2. The PID field screening of the soil samples provided a qualitative indication of the presence of petroleum hydrocarbons. The screening procedure consisted of scraping the top soil layer collected in the middle tube to expose fresh soil and scanning the vapors emitted from the soil. The PID measures total ionizable compounds in air in parts per million by volume (ppmv) in relation to a select standard. The standard used for this investigation was a 25 ppm benzene calibration gas. Calibration was performed prior to use in the field. For the protection of the field crew, the PID was also used to measure the total volatile concentrations in the breathing zone prior to and during the drilling of the soil borings. No volatile concentrations were detected during the field screening of the soil samples or while monitoring the breathing zone. The results of the PID field screening are recorded on the bore logs (Plate Nos. 4 and 5). 5.4 Monitoring Well Installation Ground water monitoring wells were constructed in the two soil borings at the completion of drilling and logging of each soil boring. A permit for the installation of the monitoring wells was obtained from the