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single disposal pile (RP-2/3/4). <br /> During construction, the refuse piles are inspected quarterly and the proper placement <br /> certified by a registered professional engineer in compliance with Rule 4.10.2 of the <br /> Colorado Permanent Regulatory Program. <br /> A surface water control system has been constructed for use during the development of <br /> the refuse piles and subsequent to reclamation of the piles. See the Surface Water <br /> section of this Findings Document. <br /> The face slopes on Refuse Area RP-1 was constructed with a 5h:1v slope. Refuse Areas <br /> 2/3/4 and 5A will be constructed with a maximum 4(h):1v slope. Illustrations 21, 42, <br /> and 42A of the approved permit application present original geotechnical field <br /> investigation and stability analysis, and subsequent testing of waste material and <br /> reevaluation of pile stability. RP-2/3/4 was originally approved with 5:1 slopes, but <br /> final reclamation designs were amended in association with RN-03, to specify 4:1 <br /> maximum slopes. Based upon the previously approved laboratory and analytical <br /> information, the Division has determined the steepening of the RP-2/3/4 structure to a <br /> facial angle not to exceed 4h:1v, to be acceptable. As long as the structures comply with <br /> the approved height limitation (i.e., 100 feet total vertical height) the pile will comply <br /> with regulatory specifications regarding slope stability. The stability of this slope was <br /> found to meet the requirements of a safety factor of 1.5. Foundation materials were also <br /> found to be stable under the weight of the refuse material. This slope will also facilitate <br /> the post-mining land use of grazing and will be compatible with the natural <br /> surroundings. <br /> Combustion of the refuse material will be minimized through compaction of the refuse. <br /> If a fire should start, individuals authorized by the mine operator will extinguish the <br /> fire. Burned waste will be removed from the disposal area after approval from the <br /> appropriate regulatory authorities. <br /> The following specific findings apply to the approved refuse disposal areas, RP-1, RP- <br /> 2/3/4, and RP-5A. <br /> A. The Division approved plans for use, construction and maintenance of a coal mine <br /> waste disposal area. The approval was based on a demonstration that no <br /> groundwater exists to a depth of at least 44 feet below the refuse area, and no <br /> springs or seeps are known to exist in the area (4.10.1(1)). <br /> B. The Division finds that an alternative subdrainage system for the coal mine waste <br /> area is not required to ensure the applicable static safety factor, stability of the fill, <br /> and protection of the surface and ground water. This is due to the demonstrated <br /> lack of groundwater in the coal mine waste area (4.10.3(5)). <br /> C. The permittee has demonstrated, based on physical and chemical analyses of refuse <br /> material and cover soil, and vegetation field trials, that the revegetation <br /> 31 <br />