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440 West Charter Way, Stockton, California December 16, 1993 Texaco Environmental Services Page 3 2 2 Soil Sampling Sod samples were collected from the soil bonngs using a 2 5-inch outside-diameter, splrt-spoon sampler, lined with three 2-inch-diameter by 6-inch-long brass tubes The sampler was driven 18 inches ahead of the augers at each sample point Samples were collected at 5-foot intervals beginning at 5 feet below ground surface (BGS) to the bottom of each boring An initial screening of the soil samples for hydrocarbon vapors was made in the field using a photoionization detector (PID) PID readings were used in conjunction with field observations to select samples for laboratory analysis Soil samples collected near the water table in MW-13, 14, 15, and 17 had PID readings ranging from 0 5 ppm (MW-13) to 16 ppm (MW-14) at 30 to 45 feet BGS Water was initially encountered in the borings between 38 and 42 feet BGS Selected soil samples were sealed, labeled, placed on ice in an insulated container and submitted to the laboratory under chain-of-custody manifest for analysis of BTEX and TPH-G by EPA methods 5030/8020/modified 8015 • 2 3 Monitoring Well Construction One groundwater monitoring well was installed in each of the five borings The monitoring wells were constructed using 20 feet of 4-inch-diameter, 0 020-inch-slot, schedule 40 PVC well screen and blank casing to the surface The annular space around and up to 1 foot above the screened interval was packed with No 3 Monterey sand, and sealed with 2 feet of bentonite and cement grout to the base of a traffic rated street box set in concrete The wells were secured with a locking, expandable well cap below a water-tight bolted lid Construction details are shown on the drill logs in Appendix A. 2 4 Surveying The site was surveyed to locate the newly installed monitoring wells and to determine their elevations in relation to mean sea level datum Elevations of the tops of the PVC well casings and street boxes were surveyed to the nearest 0 01 foot The surveyor's map and data is enclosed in Appendix B The resulting site plan is shown in Figure 2 25695um RpT GROUNDWATER TECHNOLOGy