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<br />compaction, permeability, grain size, hydrometer, Atterberg limits, pin hole <br /> <br /> <br />tests and triaxial compression tests. The laboratory testing performed <br /> <br /> <br />on remolded samples of borrow soils consisted of grain size, hydrometer. <br /> <br /> <br />Atterberg limits, compaction permeability, triaxial compression and pin hole <br /> <br /> <br />dispersion tests. <br /> <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />b. Drilling Program <br />The drilling program consisted of nine rotary wash borings drilled <br />to depths ranging from 60 to 127.5 ft which totalled 703 lineal ft of <br />drilling. Because of variations in field conditions the field program <br />became more extensive than originally planned. . Five borings were drillE!d <br />along the dam axis and four borings were drilled in the potential borrow areas <br />upstream of the dam. The drilling program commenced on May 26, 1982 and was <br />completed on June 9, 1982. A list of the borings showing the approximate <br />surface elevation and the total depth drilled is presented on Table III-2. <br /> <br />The field exploration program was conducted and supervised by an exper- <br /> <br /> <br />ienced geotechnical engineer. The borings were drilled using a 4 x 4 truck <br /> <br /> <br />mounted Failing Model 1500 rotary wash drill rig. To prevent caving of the <br /> <br /> <br />soils from the sides of the borings each hole was stabilized with drilling <br /> <br /> <br />mud. A 5-ft length of 5-inch diameter casing was used at the surface to <br /> <br /> <br />facilitate the drilling procedure. Relatively undisturbed soil samples were <br /> <br /> <br />obtained for classification and laboratory testing purposes with a Dames & <br /> <br /> <br />Moore Type U sampler and/or a Pitcher Tube sampler. Standard penetration <br /> <br /> <br />tests (SPT) were also performed at frequent intervals in the borings. The SPT <br /> <br /> <br />sampler was driven using a 140 pound hammer dropping 30 inches. The blows for <br /> <br /> <br />each of the three successive 6-inch intervals at each sampling depth were <br /> <br /> <br />recorded. The blows for the last two 6-i.nch intervals were summed to obtain <br /> <br /> <br />the blow count as blows per foot. To drive the Dames & Moore Type U sampler a <br /> <br /> <br />360 pound hammer dropping 24 inches was used. Coring with a 5-ft core <br /> <br /> <br />barrel was utilized in some of the harder zones of the Fox Hills and Pierre <br /> <br /> <br />Shale Formations. <br /> <br />III-12 <br /> <br />I <br />I <br />I <br />I <br />I <br />