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KLEINFELDEA <br /> 3 SOIL ASSESSMENT <br /> To assess the presence of petroleum hydrocarbons in the soil and evaluate the lateral and <br /> vertical extent of contamination, soil samples were collected from nine borings drilled <br /> radially around the fuel tanks excavation area. The locations of the backfilled excavation <br /> area and soil borings Pre shown on Plate 2,Boring Location Map. <br /> 3.1 DRILLING AND SAMPLING PROCEDURES <br /> On May 8 and 9, 1989, Borings B-1 through B-9 were drilled at the site. Borings B-1 was <br /> drilled approximately 3 to 5 feet from the south edge of the excavation. Borings B-2, B-3, <br /> and B-5 were placed approximately 20 feet radial-iy away from the edge of the excavation in <br /> a north,west,and east direction,respectively. A second set of borings, B4,B-6, B-7, B-8, <br /> and B-9, were drilled 30 to 60 feet radially away from the edge of the excavation. Soil <br /> samples were collected at 5-foot intervals from the ground surface to the termination depth <br /> of each boring. The borings were advanced to depths ranging from 215 to 26 feet below <br /> the ground surface,. <br /> During the sampling collection, an experienced environmental geologist classified the <br /> subsurface soil and logged the boreholes. Descriptions of the soil encountered in each <br /> boring and identification of the sampling intervals are presented on the Log of Borings, <br /> Plates 4 through 12 (Appendix A). A copy of the Unified Soil Classification System (used <br /> f f to identify soil)is included as Plate 3A and 3B(Appendix A). <br /> The soil encountered in the borings consisted of interbedded clay,silty clay,clayey silt,and <br /> ,. rine to medium grained sand. In general, clay and silt was encountered. from 0 to 20 feet <br /> below the ground surface, and sand was encountered 21 to 26 feet below the ground <br /> surface. Soil samples were generally moist, except for samples collected at the bottom of <br /> B-1 which were wet. Free water was observed in Boring B-1 at a depth of 23.5 feet below <br /> One ground surface. The remaining eight borings were drilled to a depth of 23 feet or less <br /> and did not encounter free ground water. <br /> At each boring location,a truck-mounted drill rig equipped with 6-inch hollow-stem augers <br /> was used to reach the desired sampling depths. Samples were collected by advancing the <br /> 188-89-960 3 <br /> ' 4 <br />