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r <br /> R , <br /> TL 489-0589-02 Page 7 <br /> Each soil boring was . drilled under the supervision of <br /> Twining's project geologist. .Soils were classified in the field in <br /> accordance with the Unified Soil Classification System (USCS) . <br /> Standard penetration'tests -were conducted in each soil boring. <br /> The standard penetration; resistance (N-value) is defined as the <br /> number of blows required to drive a split-barrel sampler into the <br /> soil. The sampler is driven by. a 140-pound: weight falling 30 <br /> inches. The sampler is lowered to the bottom: of the soil boring. <br /> is <br /> and set by driving it an initial six inches. It is then driven an <br /> additional 12 inches and `the= number of blows required to advance <br /> the sampler the additional 12 -inches is recorded as the standard <br /> penetration resistance or N-value. <br /> Following the. collection of the soil samples, the soil borings <br /> were backfilled with a cement-slurry mix to site grade. Soil <br /> cuttings generated from the drilling Operations were containerized <br /> g g <br /> in 55-gallon steel drums and stored on-site. , <br /> 4 .3 Decontamination Procedures: Prior . to drilling <br /> operations, the auger and associated drilling equipment were <br /> thoroughly cleaned using a high pressure hot water (steam) washer. <br /> The hat water washer has a pressure of :1,200 pounds per square inch <br /> and a ' water temperature of 210 degrees Fahrenheit. In addition, <br /> the split-barrel sampler. was' washed in a txisodium phosphate <br /> solution, rinsed in tap water, and air-dried prior to its initial <br /> use and between each sampling -event. These decontamination <br /> procedures reduces the possibility of cross contamination between <br /> sampling locations. <br /> �ieawi�rriirigC�j_o'raauee.d"- <br /> Fresno Modesto Visalia Bakersfield <br />