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• Bowie Formation (undisturbed): ~ = 17°, c = 1,500 psf (Lincoln DeVore, Feb. <br />1997) <br />Bowie Formation (fill material): ~ = 41°, c = 0 psf (Ceps, 1970) <br />For the worst-case road configuration, as shown on the Facilities Details - II West Coa] <br />Refuse Facility (Map 2.05-M3 (Sheet 3 of 3)), and using the noted material properties, <br />the calculated Factor of Safety for 1 H:1 V cut slopes is 1.88 and the calculated Factor of <br />Safety for 1.SH:1V fill slopes is 1.35, as documented by the Geotechnical Stability <br />Analyses, Appendix A. Given that the calculated Factors of Safety exceeds the required <br />regulatory Safety Factors of 1.5 for cut slopes and ].3 for fill slopes, haul road <br />construction for the worst-case configuration or any lesser cuUfill slope configuration <br />should be stable. <br />ROAD CONSTRUCTION, INSPECTION, AND MAINTENANCE <br />Road construction methods are similar for all classes of roads. Construction generally <br />involves initial clearing of vegetation, recovery or windrowing of available soil materials <br />(where operationally feasible), cut-fill excavation and placement or sidecast conswction <br />(light-use roads only), installation of drainage structures, grading, and placement of <br />surfacing materials. Topsoil is generally not recovered for light-use roads in steep <br />terrain, where sidecast construction is necessary, due to practical operational and safety <br />considerations. For haul roads, fill and embankment construction involves placement and <br />• compaction of fill materials in horizontal lifts approximately 12 inches deep over the <br />width of fill or embankment. When rock or rocky material is used for fills, lifts do not <br />exceed the maximum size of the rock present, and in no case exceed 30 inches in depth. <br />Cut/fill and any required borrow activities are conducted to specifically avoid inclusion <br />of any vegetation, organic materials, soils, coal slack, wet or frozen materials, and <br />potential acid-or toxic-forming materials in road fills and surfacing materials. Each lift is <br />moistened, if necessazy, to achieve optima] compaction and construction or compaction <br />equipment is run back and forth over the fill until the design compaction of not less than <br />90 percent of maximum unit dry weight is achieved. Compaction is carved to the edge of <br />the fills so that final embankment slopes are firm and stable. Where fills are placed on <br />existing slopes which are steeper than SH:1 V, the slopes are benched and scarified and <br />the loosened material blended with the fill during placement and compaction. Road <br />benching configuration and requirements are illustrated by the Typical Road Cross- <br />Section (Worst-Case CutslFills) shown on the Facilities Details Map (Map 2.05-M3 <br />(Sheet 3 of 3)). <br />Temporary erosion and sediment control measures are implemented during road <br />construction to control runoff, sediment loss, and sediment transport from the associated <br />disturbed areas. Such measures include the use of temporary berms and ditches and <br />placement of silt fence and/or straw bales to intercept and control drainage. Drainage <br />ditches are provided at the toe of all cut slopes and at other locations along the road <br />alignment, as required to effectively control erosion and runoff flows. Where ditch <br />• installation is required, ditches are cut to the design configuration and grade following <br />completion of road construction. On completion of road ditches to the design <br />TR-43 4 September 2003 <br />