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A ~- 3 <br />A-2 ROCK CORE BORINGS AND SAMPLING <br />All borings were fully cored once bedrock was encountered, <br />Borings E-1 through E-3 were cored to an elevation below the <br />bottom of the "F" seam to enable an evaluation of floor con- <br />ditions and sampling of floor materials for subsequent testing. <br />Borings A-7 and A-8 were cored approximately 10 feet into bed- <br />rock to verify the presence of bedrock and to enable an evalu- <br />ation of its character. Boring A-6 did not encounter bedrock. <br />Coring was accomplished using a carbide or diamond tipped <br />coring bit and 5-foot double tube NXWL (NX wireline) core <br />barrel with a split inner tube. An attempt to use air flushing <br />in order to maximize the recovery of loose or friable materials <br />proved unsuccessful on the first hole due to the amount of <br />water encountered in the hole. Subsequently, all cored holes <br />were drilled using water or, if water losses had to be con- <br />trolled, "thick and thin" degradable drilling mud, as the <br />flushing medium. PVC pipe with perforated sections was in- <br />stalled in all borings subsequent to their completion to en- <br />able continued observations of ground water levels in the area. <br />A detailed geotechnical log was maintained during drill- <br />ing. The system used to log the borings is presented on <br />Plate A-9, and the boring logs are presented as Plates A-10 <br />through A-14. A quantitative description of the geotechnical <br />character of the core included the following items: <br />1. Rock type and description of rock material. <br />2. Description of rock defects such as joints and <br />bedding plane fractures. <br />3. Length of each core run and the percentage of <br />the run which was recovered. <br />4. Rock Quality Designation (RQD) for each core run. <br />uwrcoao cowuna, Nc <br />