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road is intended to be left after mining has been completed ( see Volume • 7, Tab 13, Page 27 for permanent roads). Maintenance or stability problems may preclude this and, in that case, the road will be reclaimed. The following corrective methods lend themselves to the area near Sta 60+00 but can be applicable, or at least considered, for any landslide or stability problem within the permit boundary. Direct Reduction of Slope Flattening the slope reduces the weight, which in turn changes the moment arm characteristics of the slice (as in stability analysis) and therefore increases the factor of safety (see Figure 25). Unfortunately there are some areas in which slope reduction is not possible. The next method may be applicable to those areas. Flattenirxt by Cuttinci Berns This method has the same effect as the above but works within the confines of the existing slope. It steepens short sections of the slope but overall reduces the weight per slice. Flattenira of Slope Without Haulirxr Material Awav Material for the upper reaches of the slope can be pushed down to the bottom of the slope. This reduces the weight at the head of the failure surface and increases the weight at the toe. Surface Drainage • Proper drainage is essential in correcting slope failures. Not only should surface drainage be diverted around the slide material but drainage on the slide material must also be considered. Cracks and fissures must be repaired, especially at or behind a scarp face where large amounts of water could enter the unstable material. Proper drainage will allow the slide material to dry out and therefore reduce the chances of further sliding. Subsurface Drainage Ground water is one of the major causes of slope failure. One method that works well in subsurface drainage is the installation of horizontal wells. A horizontal drilling machine is set up at the base of the slide and drills horizontally into the unstable material. As the auger retracts it leaves behind perforated pipe. This allows the grourxi water a controlled place to exit the slide material. Vegetation After the slide has been at least partially stabilized, the slide area should be revegetated, if possible. The root network will help bind the soil together and the vegetation will also lower the infiltration rate of the soil. Use of biotechnical slope restoration, which is a combination of mechanical and biological elements to stabilize slopes, is gaining in popularity and may also be considered. Buttress or Retaining Wall A buttress can be constructed at the base of a slide area after removal • of waste material has been accomplished. The buttress adds a counterweight to the slide area and actually produces a negative movement 11