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r <br /> IT CORPORATION <br /> r 'V 2.0 DRILLING AND WELL INSTALLATION <br /> The initial drilling program conducted on February 27 and 28, 1985 was a <br /> site assessment to provide basic subsurface soil and hydrogeologic <br /> information at the station. Four monitor wells (MW-1, MW-2, MW-3, and <br /> MW-4) were installed during this phase of the investigation, as shown in <br /> Figure 2,1. The first well (MW-1), drilled to a depth of 45.5 feet, was <br /> completed as a ground water monitor well. Since the water table was <br /> deeper than 30 feet, the remaining three wells (MW-2, MW-3, MW-4) were <br /> completed in the unsaturated zone above the water table as vadose wells <br /> _ to a depth of 20 feet, All four borings were drilled with a truck- <br /> mounted drilling rig equipped with 8-inch hollow-stem, continuous-flight <br /> augers. <br /> h <br /> The objective of the second drilling program was to determine the extent <br /> of the hydrocarbon plume discovered during the initial drilling phase. <br /> On-site work was conducted an March 26, 1985 and March 29, 1985. During <br /> this time, three borings were drilled at the locations shown in <br /> Figure 2.1. These borings were drilled with a truck-mounted drill rig <br /> equipped with 8-inch hollow-stem augers to depths Of 20 feet (MW-5 and <br /> MW-6) and 30 feet (MW-7). All three borings were completed as vadose <br /> wells of the type shown on the individual boring logs, Plates 2 throat': <br /> The objective of the third drilling program was to install two addi- <br /> tional ground water monitor wells to determine the ground water gradient <br /> and if the ground water was contaminated. Well MW-1 was drilled out and <br /> installed with a 38-foot surface seal as shown on Plate 3. Drilling <br /> I <br /> began on May 20, 1985 and ended. May 29, 1985 using a truck-mounted drill <br /> rig equipped with 6-inch 0.0, continuous-flight, hollow-stem augers. <br /> 2.1 SOIL SAMPLING <br /> ------ <br /> Undisturbed sail samples were collected in every borehole at 5-foot <br /> intervals using a 2-inch I.D. California sampler and field tested for <br /> hydrocarbon contamination using a GX-3A explosive gas analyzer, fp,e <br /> 2 <br />