Laserfiche WebLink
2.3 Present Investigation <br /> The assessment included the drilling of three soil borings in the <br /> area of the underground storage tanks (UST' s) , one boring near the <br /> fueling islands, one boring near the drain between UST' s and the <br /> pump islands, and one boring near the former above-ground waste oil <br /> storage tank <br /> Drilling was performed on June 23 , 1993 . Borings #1 through #3 were <br /> drilled at a 200 angle from vertical, and extend to a vertical <br /> depth of 28 feet beneath the UST's (Figure 4) . Boring #4 was <br /> installed west of the fueling islands, and was also drilled at an <br /> angle of 200 from vertical. Borings #5 and #6 were vertical, and <br /> were advanced to a depth of 15 feet. At the request of Mr. Harlin <br /> Knoll of the San Joaquin County PHS/EHD, boring #5 was located <br /> adjacent to a drain between the UST' s and the fueling islands. <br /> Boring #6 was drilled near the location of the former above-ground <br /> waste oil storage tank (Figure 2) . <br /> One water sample was collected from the domestic well on site to <br /> determine the possibility of groundwater contamination. <br /> 3. 0 PROCEDURES <br /> 3.1 Drilling <br /> The borings were advanced using a truck-mounted drilling rig <br /> equipped with 8-inch outside diameter hollow-stem augers. The B-57 <br /> drill rig and two-man crew were supplied by Woodward Drilling <br /> Company. Auger returns were placed on plastic sheeting on-site and <br /> covered pending analytical results. All borings were backfilled <br /> using concrete-bentonite slurry for the entire depth. <br /> 3.2 Soil Sampling <br /> Discrete soil samples were collected at five-foot intervals ahead <br /> of the drill bit using a split-tube sampler loaded with three pre- <br /> cleaned 2 by 6-inch brass tubes. The sampler was driven into the <br /> soil with a 140-1b hammer, and the number of blows required to <br /> advance the sampler in six-inch increments was recorded on the <br /> boring log. To avoid cross contamination, the sampling equipment <br /> M was washed in a tri-sodium phosphate (TSP) solution and rinsed <br /> twice with water prior to each sampling run. <br /> For each sample, both ends of the bottom tube were covered with <br /> aluminum foil, capped, and sealed with tape. The samples were <br /> labeled, logged on a chain of custody form, and stored on ice <br /> pending transmission to Sparger Laboratories in Sacramento. <br /> 2 <br />