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RECLAMATION - BENCHES <br /> • Geotechnical and other problems include sloughing, undercutting the crest <br /> of cuts, erosion, rilling and erosion gullies, minor slides, mudflows, <br /> accumulations of debris below cut or fills, rockfall, ground water seeps, <br /> larger stability problems of fills, ponding on fills, seepage from the fill <br /> foundation and avalanche hazards. <br /> Based on these problems and on the overall evaluation of the road and mine <br /> bench conditions, several potential reclamation problem areas have been <br /> developed. They are regarded as typical for the Coal Basin conditions. <br /> • Avalanches are a natural phenomenon in the area and the development of <br /> mine benches has not increased the avalanche danger. Haul roads or mine <br /> benches act as artificial barriers to individual avalanche paths and reduce <br /> their energy. They are thus beneficial in reducing the avalanche hazard. <br /> RECLAMATION PROBLEM TYPES <br /> Essential reclamation problems identified by Geo-Hydro, and the reclamation <br /> concepts recommended, include: <br /> High Rock Cut <br /> • Typical for most mine benches, the high rock cut is either in Mancos Shale <br /> or in the Mesaverde. Mesaverde rocks are probably more important from <br /> the geotechnical and reclamation point of view. As the bedding is horizontal <br /> or dips at a flat angle into the mountain, the general (overall) stability is <br /> good. They slope cut is typically very steep, frequently up to vertical. <br /> Because of the rock mass nature, and because no controlled blasting <br /> methods were used during the cut excavation, the cut surface is rugged, <br /> uneven, with loosened blocks on the surface. The cut portion close to the <br /> crest may have stability problems if it is in colluvial soils or weathered rocks. <br /> Rockfall problems are common; the debris accumulate at the toe of the cut. <br /> The cut slopes have not been benched and access to the slopes is <br /> practically impossible. <br /> The reclamation concept is to place a low buttress at the toe of the cut to <br /> increase the cut's long-term stability, then contour the buttress so that it <br /> serves as the catching space for the rock fall. <br /> High Thick Fill <br /> High thick fill on a mine bench was constructed with material obtained from <br /> the excavation of the bench cut or because of the need to enlarge available <br /> 5 <br />