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• or intersect the ridge. The pile was designed with side slopes of <br />2(H):1(V) and with 20-foot benches (terraces) located at vertical <br />spacing of no more than 50 feet. Slope stability analyses of this <br />pile configuration proved that the factors of safety were <br />satisfactory. Over ten years of experience with this slope <br />configuration and construction method has proved that the design <br />of the pile is adequate from the stability point of view. <br />Surface drainage of the pile has been routed into a single <br />sedimentation pond (West Ridge waste pile sedimentation pond) by <br />the west and east side drainage ditches. The sedimentation pond <br />is located on the southeast end of the ridge, southeast of the <br />waste pile. <br />The storage volume of the original waste pile was estimated to be <br />approximately 130,000 cubic yards. <br />3.0 PROPOSED 1994 DESIGN MODIFICATIONS <br />3.1 FOOTPRINT, CONFIGURATION AND CONSTRUCTION METHODS. The <br />proposed footprint is shown in Figure 1. Approximately two thirds <br />of the pile (in north-south direction) comprise the existing <br />waste pile, while the north third comprises the proposed <br />• modification. The modification calls for a waste pile width (in <br />west-east direction) larger than the original design. On the west <br />side, the toe of the pile extends close to the existing half <br />culvert and to the west side ditch. On the east side, the pile <br />extends also farther to east than the original design. On north, <br />the top of the pile coincides with the level of the crushing and <br />screening level fill, as in the original design. <br />Two 20-foot benches (terraces) are designed at elevations <br />approximately 6865 and 6905. The benches width, cross- and <br />longitudinal slopes are identical to the original design. <br />The waste pile construction methods, topsoil handling, access, <br />site preparation, waste disposal, maintenance and reclamation <br />shall comply with the original design. <br />3.2 STORAGE VOLUME. The storage volume of the modified pile is <br />approximately 131,000 cubic yards (159,000 tons). <br />3.3 STABILITY. Since the slopes and the waste pile configuration <br />of the modified waste pile coincide with the original design, and <br />the waste material properties have not changed, no further <br />stability analyses are required. The modified waste pile will <br />support a larger section of the crushing and screening level fill <br />south slope; this is a more favorable solution than in the <br />• original design. <br />2 <br />