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a hydrogeologist . Geologic samples were collected continuously <br /> ' during drilling using a 1 . 5-foot split spoon sampler driven ahead <br /> ' of the augers. The samples were tested for hydrocarbon presence <br /> using a photoionization instrument calibrated for benzene. In <br /> ' addition, the samples were geologically classified and logged. <br /> The logs and soil gas testing results are presented in Appendix <br /> B. All drilling was conducted using decontaminated augers and <br /> t clean sampling equipment . Eight-inch diameter holes were bored <br /> with hollow stem augers to a depth of about 12 to 15 feet . Soil <br /> removed from the borings was staged on plastic and covered <br /> securely. A 2-inch diameter schedule-40 PVC-threaded casing with <br /> flush joints, attached to an 8- to 10-foot ( 0 . 02-inch) slotted <br /> PVC casing, was installed through the augers. Attached to the <br /> screen was a two-inch riser pipe with threaded couplings . When <br /> ' the auger was removed, a fine sand pack was installed above the <br /> screen. This was followed by a bentonite seal at least one foot <br /> thick . The remainder of the annular space was filled with neat <br /> cement. An inspector from the San Joaquin County Health <br /> Department supervised the addition of neat cement . Well M-1 was <br /> ' fitted with a locking casing in concrete while a vault box and <br /> locking device were installed in concrete around Well M-2 . The <br /> wells were developed by bailing, and monitoring well construction <br /> details are illustrated in Appendix C. <br /> The exploratory test holes and monitoring wells were sur- <br /> veyed on March 11 , 1988, to determine their precise location, <br /> elevations of ground surface, and the top of the casing . Table 1 <br /> presents monitoring well and test hole ground and casing <br /> - 6 - <br />