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1 <br /> 1 45 E Harding Way, Stockton, Califomia September 1, 1993 <br /> Chevron USA Products Company Page 4 <br /> 3.3 SOIL SAMPLING <br /> tDuring the drilling operations, soil samples were collected at five-foot intervals, beginning at <br /> approximately 5 feet below grade to the bottom of the boring Samples were collected using a 2 5-inch <br /> ' O D split-spoon sampler, lined with three 2-inch-diameter by 6-inch-long brass sample tubes The <br /> sampler was driven 18 inches ahead of the augers at each sample point Soil samples were field <br /> 1 screened using a photo-ionization detector (PID) One sample from every five-foot interval was seated <br /> with aluminum foil, capped, taped, labeled, placed on Ice In an insulated container and delivered to a <br /> ' State of Califomia-certlfied laboratory <br /> The field geologist maintained a complete log of the materials encountered during drilling using the <br /> ' Unified Soil Classification System (Appendix B) The drilling operation was supervised by a California <br /> registered geologist <br /> ' Ten soil samples from all of the soil borings were selected for analysis Each sample was analyzed for <br /> benzene, toluene, ethylbenzene and xylenes (BTEX), and TPH-G by Environmental Protection Agency <br /> (EPA) methods 5030/8020/8015 <br /> L3.4 MONITORING WELL INSTALLATION <br /> ' One monitoring well was installed in each soil boring (Appendix B) The monitoring wells were <br /> constructed of 2-inch diameter, schedule 40 PVC casing with flush threads, and 0 020-inch-slot well <br /> ' screen The well screen of MWA 2 was installed from a depth of approximately 65 feet to a depth of 30 <br /> feet below grade, while the well screen of MW-13 was Installed from a depth of 65 feet to 40 feet below <br /> ' grade A sand filter was placed around the well screen to a height of approximately 2 feet above the top <br /> of the screen The wells were completed with a bentonite and neat-cement seal, to grade The wellhead <br /> was protected by a locking cap and a traffic-rated street box with a water-tight bolted lid Well <br /> construction details are presented in the drill log (Appendix B) Following installation, both new wells <br /> were surveyed to mean sea level datum for both horizontal and vertical control (Appendix C) <br /> 35 MONITORING WELL DEVELOPMENT <br /> On July 22, 1993, MW-12 and MW-13 were developed using hand bailing and pumping methods to <br /> remove fine-grained sediments from the well and filter pack Approximately three well volumes were <br /> k---7Eg GROUNDWATER <br /> 3399EAR RPr TECHNOLOGY <br /> 1 <br />