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I • downward to minimize potential destabiliTation of the soil mass that would otherwise result from <br />cutting out the tce of a marginally stable slope. <br />Visual slope monitoring, consisting of wood lathe or steel stake sight lines will be established <br />approximately 10 feet above the top of the cut slope prior to excavation activities. For smooth <br />slopes, additional sight lines will be established approximately I/3 of the slope length below the top <br />of the cut and at other intermediate slope locations as dictated by field conditions. Benched slopes <br />will be constructed such that the overall slope of the series of benches matches finished design <br />slopes. <br />Surface diversion ditches approximately 15 feet above the top of the cut will be installed as needed <br />to capture Clearwater runoff and direct it beyond the boundaries of the cut slope. Groundwater <br />encountered during excavation work will be removed from the cut by lined ditches or drains <br />extending outside the lateral perimeter of the cut slope. <br />Quality control in the construction of cut slopes is a performance requirement of the Contractor, <br />and will be monitored by MCC Construction Management personnel on a daily basis. If movement <br />or excessive groundwater is encountered during the construction of individual slopes, the <br />Contractor will be required to cease related wnstnrction activities at the site until stability <br />evaluations and design modifications can be performed. The scope of stability evaluations and <br />specific design modifications will depend on site specific field conditions and cannot be predicted at <br />this time. A discussion and summary of probable slope failure mitigation measures is included in <br />Part 4 below. <br />• <br />Part 4 Slone Failure Mitigation <br />Approaches to the mitigation of slopes that may fail during the construction of the facilities in <br />Sylvester Gulch can be categorized as follows: <br />• Avoid the problem, <br />• Reduce the forces tending to cause movements, and <br />• Increase the forces resisting movement. <br />Avoiding the Problem <br />Two practical altematives exist under the category of avoiding the problem, namely minor <br />realignment of the road and cut and removal of the unstable material. The realignment alternative <br />is limited by the physical constraints of Sylvester Gulch, the existence of additional potentially <br />unstable landslide masses, and future development altematives. Removal of unstable material as <br />an alternative is constrained by the volume of material that may have to be removed. Mitigation of <br />slope failures using these altematives require that the extent of the unstable material be mapped, <br />and if practical the depth of the material be determined. <br />• <br />