Laserfiche WebLink
• Samples rich in coal were collected from two storage sites: the warehouse <br />pile (initial waste rock pile) and the stockpile near the breaker building. <br />These piles are generally high-ash coal temporarily stored in conical piles <br />each sitting at a 40o angle of repose. They are coarse. <br />Grain Size <br />Soil: The liquid limit is 31% and plastic index is 17%, 80% pass a /I40 sieve <br />size, the grain size for fine to medium sandy and gravelly clay. <br />Refuse Material: For the coal-rich refuse, 80 percent pass a 112 inch <br />opening (fine gravel to coarse sand) while the clay-rich (underground <br />development waste) samples are finer than f/8 sieve. See Appendix C. <br />Density <br />Soil: The silty and clayey colluvium dry density ranges from 87 to 120 pcf <br />and field moisture of 10% to 20%. See Appendix A. <br />Refuse Material: Based on consolidated tests, the refuse material has a <br />• saturated density of 60 to 149 pcf depending on clay content. Moisture at <br />full saturation ranges from 18% to 30%. <br />Bedrock: The bedrock will have a maximum density of 150 pcf and a <br />minimum of 100 pcf when weathered. <br />Typical sandstone bedrock properties are: compressive strength of 12,960 to <br />16,000 psi and tensile strength of 1,010 to 1,536 psi. Shale bedrock strength <br />values range from 9,000 to 10,000 psi in compressive and from 600 to 1,190 <br />psi in tensile strength. <br />Shear Strength <br />The shear strength properties are the cohesion and angle of (internal) <br />friction. For the colluvium, these properties were determined by direct <br />shear tests on undisturbed samples and by triaxial tests and then confirmed <br />by back calculation of slides in the area. Similar tests were performed for a <br />few bedrock cores. The tests on boring and core samples were performed by <br />-15- <br />• <br />