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The TR-63 application included a thorough slope stability analysis performed in <br /> accordance with the prudent state-of-the-art slope analysis for the original design in <br /> 1985, and for the redesigned pile in 1992. Material strength values were derived from <br /> on-site sample testing and nearby previously reported test results. Piezometer <br /> observations, falling head parameter tests and analytical projections were completed in <br /> order to predict appropriate phreatic surfaces within the proposed waste structure. Data <br /> for the 1992 analysis utilized data collected for the 1985 analysis. <br /> The applicant has committed to the installation and quarterly monitoring of three sets of <br /> survey monuments to monitor slope stability of the waste structure. One row of <br /> monuments has been installed parallel to the state highway adjoining the toe of the <br /> waste pile on 100-foot intervals. Two additional rows of monuments have been <br /> installed perpendicular to the highway on the facial slope of the pile at 50-foot interval <br /> spacing. The operator has also committed to quarterly reporting of visual inspections of <br /> the topsoil, non-toxic soil cover stockpiles, and refuse pile. <br /> For the LRP, drainage will be controlled by a series of drainage ditches, terraces, and a <br /> sedimentation pond. Since the pile will be constructed in phases, the drainage system <br /> will also be built in phases. All disturbed area drainage from the topsoil piles, subsoil <br /> stockpile and waste pile will be routed to the sedimentation basin at the northwest <br /> corner of the lower waste pile (MB-2R). <br /> The design incorporates several permanent drainage features into the plan. After final <br /> reclamation of the pile, the terraces will be barricaded with rocks or berms to prevent <br /> access to the pile. However, the terraces will still function to control runoff from the <br /> pile. A hundred-year diversion ditch has been constructed around the perimeter of the <br /> pile to permanently collect any runoff from the site and safely route it to the natural <br /> drainage system. For a discussion of the hydrologic effects of the waste pile on both <br /> surface and groundwater, see the hydrology section in the Probable Hydrologic <br /> Consequences section of this findings document. <br /> The Division has granted a variance from Rule 4.10.4(5), to cover the LRP with a <br /> minimum of four feet of non-toxic and non-combustible material. The operator was <br /> able to demonstrate that there would be no expected detrimental effects on revegetation <br /> and that the probability of spontaneous combustion occurring is very low with a <br /> proposed soil cover of 18 to 24 inches. A satisfactory revegetation, erosion, and <br /> spontaneous combustion monitoring plan was proposed for the LRP. Also, contingency <br /> plans were proposed for all three concerns in the event of failure or poor reclamation <br /> success. Therefore,upon reclamation of the LRP, the operator will cover the pile with <br /> 18 to 24 inches of topsoil and subsoil. For more information, please see information <br /> regarding Technical Revision No. 53. <br /> The West Elk Mine was permitted to accept and dispose coal mine waste from other <br /> neighboring operations, if comparable in characteristic to MCC's refuse. In the past, <br /> MCC has accepted sediment clean-out from the Terror Creek Loadout and development <br /> waste from Bear Coal Company (4.10.1(2)). <br /> 51 <br />