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1. General Plan and Scope <br /> According to stipulation No. 07 issued by the MLRB of the State <br /> of Colorado, the design of the permanent coal waste bank at <br /> National King Coal Mine must satisfy the requirements stated in <br /> mine regulations 2 . 05. 3 (8) , 2 .50. 3 (9) , 2 . 05. 3 (10) , 4 . 10 and 4 . 11. <br /> This document attempt to address these regulations in an manner <br /> appropriate to the scale and scope of the National King Coal Mine <br /> site. <br /> The coal refuse will be mine waste rock extracted over the life <br /> of the mine. The material is composed of dense, medium grained <br /> sandstone with occasional shale and carbonaceous shale partings. It <br /> is estimated by National King Coal that 30, 000 cubic yards of mine <br /> waste will be extracted and placed in the waste bank. Of this <br /> approximately 5000 cubic yards has been removed and currently sits <br /> on the west end of the proposed waste bank. <br /> The waste bank will be located east of the mine entrance, <br /> beginning just east of the shop building and extending up the <br /> eastside drainage approximately 900 ft. The exact location can be <br /> seen on the accompanying map C-4 . The existing coal waste bank will <br /> be modified to meet the design specifications of this report and <br /> incorporated into the permanent structure. <br /> A limit equilibrium static analyses was performed using effective <br /> stresses to assure long term stability of the bank. A typical cross <br /> section is shown in figure 1. A relatively flat 3h: ly slope was <br /> used for the face of the waste pile. This analysis provided a range <br /> of factors of safety between 1.85 and 2 .74, well above the required <br /> 1. 5. A detailed discussion and supporting materials are given in <br /> section 2 . An intercept channel will be constructed at the top of <br /> the bank to divert flow originating above it away from the bank and <br /> into the eastside drainage. Similarly, a channel will be <br /> constructed at the bottom the waste bank to intercept runoff from <br /> the pile. An underdrain system will be constructed beneath fill and <br /> will drain into the eastside drainage. <br /> The mine is located in a geologically stable area which rates low <br /> in seismic activity. Because the waste bank lies below the mining <br /> levels, there will be no subsidence effect either. <br /> 2 . Detailed Design <br /> Waste Material Properties <br /> As stated the coal refuse is mine waste rock composed of dense, <br /> medium-grained sandstones. This material comes from the Menefee <br /> Formation, Mesa Verde Group, Upper Cretaceous age. The sandstone is <br /> a quartz sandstone with calcareous to slightly ferruginous cement <br /> and minor argillaceous and carbonaceous shale partings. <br /> 1 <br />