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1. General Plan and Scope <br />This document combines all previous reports on the waste pile into one <br />report. Detailed documentation is not included herein. Please refer to the original <br />reports for complete documentation and other details. The previous reports are <br />titled Waste Bank Design, Technical Revision 1, April 1991 and Waste Bank <br />Design Technical Revision, September 1991. <br />According to stipulation No. 07 issued by the Division of Minerals and <br />Geology of the State of Colorado, the design of the permanent coal waste bank at <br />National King Coal Mine must satisfy the requirements stated in mine regulations <br />2.05{8), 2.50{9), 2.05(10), 4.10 and 4.11. This document attempts to address <br />these regulations in a manner appropriate to the scale and scope of the National <br />King Coal mine site. <br />The coal refuse will be mine waste rock extracted over the life of the mine. <br />The material is composed of dense, medium grained sandstone with occasional <br />shale and carbonaceous shale partings. With the addition of the proposed wash <br />plant the production of waste rock will increase with an estimated ultimate volume <br />of one million cubic yards. <br />The waste bank will be a valley fill type pile located in the east drainage. The <br />existing coal waste bank, approximately 25,000 cubic yards, will be modified to <br />meet the design specifications stated in this report and will be incorporated into <br />the permanent structure. <br />A limit equilibrium static analysis was performed using effective stresses to <br />assure long term stability of the bank. The face of the bank will have a surface <br />slope of 2.5:1 or less. The east side drainage will diverted around the pile on the <br />north side and will be tied into the clear water diversion system. An intercept <br />channel will be constructed on the south side of the bank to collect contaminated <br />runoff from the pile and runoff from adjacent areas and route it to the <br />sedimentation ponds. An underdrain system will be constructed beneath fill and <br />will also drain into the ponds. <br />The mine is located in a geologically stable area that rates low in seismic <br />activity. Because the waste bank lies below the mining levels, there will be no <br />subsidence effect. <br />2. Detailed Design <br />Waste Material Properties <br />As stated, the coal refuse is mine waste rock composed of dense, medium- <br />grained sandstones. This material comes from the Menefee Formation, Mesa <br />Verde Group, Upper Cretaceous age. The sandstone is a quartz sandstone with <br />January 1998 <br />