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s — ��.* of jtx+ x - <br /> M• <br /> Woodward-Clyde Consultants <br /> 2.0 <br /> FIELD INVESTIGATION <br /> e i � <br /> The following sections describe WCC field investigation Activities beginning August 12, 1991 <br /> and ending on August 20, 1991. The field investigation was completed in two phases: the <br /> subsurface soil investigation and the groundwater investigation. The subsurface soil <br /> investigation was conducted from August 12, 1991 to August 15, 1991,and the groundwater <br /> investigation was conducted on August 20, 1991. i <br /> 2.1 SOIL INVESTIGATION E <br /> Thrt borings were advanced around tre gasoline tank excavation with a t! k moLnted <br /> Mobile Drill model B-61 equipped with hollow stem augers (Figure 2). The borings were <br /> advanced to 90 feet(10 feet below tine groundwater surface). Soil samples were collected <br /> every five f,'et with atwo-'inch diameter California modified sampler fatted with thin wailed <br /> - brass tubes. To collect tach soil sample, the augers were advanced to the desired depth, the <br /> drilling assembly e removed from the augers, and the sampling assLmbly was lowered <br /> through the center of the augers. The sampling assembly was driven IS inches into the soil <br /> (12 inches when the resistance =Nas high;: The number of blows repaired to advance tae <br /> sampler every six inches was counted and recorded for each sample in order so estimate the <br /> consistency or density of the soil. After the sampling assembly was driven the prescribed <br /> >: distance,it was removed from the augers. The sampler was opened and the brass tubes were <br /> removed from the sampler. The soil was extracted from the tube above the bottom tube and <br /> was examined and classified by a geologist according to the Unified Soil Classification j <br /> System. The sample was placed in a resealable plastic bag for approximately five minutes E <br /> r., r . <br /> and the headspare was measured for volatile organic compounds (VOC) using a <br /> phctoionization meter(Hnu). The results were recorded in tine field notes. The bottom tube <br />' was prepared for laboratory analysis. The ends of the brass tube were covered with z <br /> aluminum foil, then with plastic caps. The tube was labeled with.the following information: <br /> sample identification(boring number and depth.of sample),date sampled, and time sampled. <br /> The tube was placed in a resealable plastic bag, then placed in an ics chest filled with ice i <br /> { <br /> for storage until the samples could be transported to the analytical laboratory. Prior to , <br /> sampling, tho sampling assembly was cleaned by scrubbing with a solution of alcanox eitd <br /> 91cov8w.MU0R rnas.wr 10-W-91IMP 2-1 <br /> is <br /> i <br />