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SOIL ASSESSMENT FOR PROPERTY ACQUISITION <br /> Intersection of Interstate 205 and Grant Line Road <br /> Tracy, California <br /> Delta Project No. 40-89-052 <br /> Page 8 <br /> Chemical analysis of soil samples collected from soil borings SB-2 (at depths of 2.5 to 5.0 feet) and <br /> SB-6 (at a depth of 6.0 feet) indicated that petroleum hydrocarbon constituents are present at levels <br /> less than the detection limit. <br /> Chemical analysis(for pesticides/herbicides)of a soil sample which was composited from soil samples <br /> collected at a depth of 0.5 foot below ground surface in soil borings SB-1, SB-3, SB-4, SB-5, and <br /> SB-6 indicated the presence of DDT at a concentration of 0.02 mg/kg (ppm). <br /> 5.0 METHODS AND PROCEDURES <br /> 5.1 Drilling and Soil Samolina <br /> Soil borings were drilled using a Mobile Drill B-53 drilling rig and 8-inch-diameter hollow-stem <br /> augers. The soil borings were advanced to a maximum depth of 10.5 feet below ground surface. <br /> Samples of subsurface soils were obtained using a California-modified or Standard split-spoon <br /> sampler. Samples were collected and examined from each of the six soil borings. A portion of each <br /> soil sample was collected in a recloseable plastic bag and allowed to reach ambient surface <br /> temperature. Headspace gas measurements of total organic vapors were made with an hNu <br /> photoionization detector (PID). The readings from the PID are recorded on soil boring logs in <br /> Appendix A. <br /> All drilling and sampling equipment was cleaned before drilling each boring using a high-pressure <br /> steam-cleaning apparatus. The split-spoon sampler was cleaned with phosphate-free soap and rinsed <br /> with water following collection of each sample. <br /> 5.2 Soil Classification <br /> All soil samples were examined in the field by a geologist and described by color, grain size, moisture <br /> content, and odor, and were classified in accordance with the Unified Soil Classification System. <br /> 5.3 Analytical Sample Selection and Preservation <br /> Two soil samples were selected for laboratory analysis from soil boring SB-2. Soil sample SB2-1 <br /> (obtained from 2.5 feet below ground surface) was selected to document hydrocarbon levels in soils <br /> directly beneath an area exhibiting visible surface staining. Soil sample SB2-2 (collected from 5 feet <br /> below ground level) was submitted to document hydrocarbon concentrations between 2.5 and 5 feet <br /> below ground level in soil boring SB-2 and to document the potential presence of hydrocarbons at <br /> the soil/ground water interface. <br />