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<br /> Plan May 17, 1991
<br /> Service Station No. 2168, Stockton, California AGS 31.409-1
<br /> first boring near the gasoline tank cavity is terminated above 30 feet below grade,
<br /> three additional soil borings will be drilled approximately 2-1/2 feet from the edge of the
<br /> tank area, equally spaced around the tank perimeter. If the first boring is drilled deeper
<br /> than 34 feet,two more borings will be drilled around the existing tank cavity using the above
<br /> criteria until two consecutive samples collected at 5-foot intervals produce PID readings of
<br /> less than 50 ppmv. In this case, a boring will not be drilled on the end opposite from the
<br /> fillport. If ground water is not encountered in the deepest boring, the last boring drilled
<br /> near the existing cavity wiit be drilled 20 feet beyond the depth of the other borings or to
<br /> ground water. i his final boring will be drilled to evaluate tl,e groundwater level or.0 log
<br /> the soil 20 feet below the last evidence of hydrocarbons. This additional information on the
<br /> subsurface will assist in any future remediation plans.
<br /> In addition, three soil borings will be drilled in the locations shown on Plate P-3 to 2.5 feet
<br /> below grade if hyZarbare not dete d using the PID in the borings around the
<br /> existing tank cavitya�ru a detected using the PID below 25 feet, the boring
<br /> depth will be adjusgI so the screened inter-91 will extend over the interval that
<br /> the PID detected s. The borings will be converted tovapor-extraction wells,
<br /> andaVETwillbeefore the tank removal. The purpose of conducting the VET
<br /> is to evaluate the f vapor recovery in the natural soil and assist in remediation
<br /> t of soil in subsequent phases of work if warranted.
<br /> Collecting Soj amnples
<br /> During drilling,soil samples will be collected at 5-foot or other appropriate intervals using
<br /> a California-modified,split-spoon sampler equipped with clean bras sleeves. Samples will
<br /> be collected by drilling the boring to a point just above ,he sampling depth and then driving
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<br /> Applied GooSysterns —_--
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