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colluvium soils collected primarily in the vicinity of the primary coal handling facilities. The <br />minimum values shown in the calculations are for a cohesion value that 90 percent of colluvium tests <br />are expected exceed, based on a statistical analysis. The maximum values shown in the calculations <br />are for a cohesion value that 10 percent of colluvium tests are expected exceed. <br />4.7.2.1 Cut Slopes <br />Cut slopes will be excavated to an overall slope of 1.5H: 1V when excavated in soil, or at a slope of <br />0.25 H:1 V when in rock, as required by Rule 4.03.1(3)(d). Cut slopes will be excavated in benches <br />to minimize the amount of excavation, as shown on the permit drawings. Slopes between the cut <br />slope benches excavated in soil will have a slope of approximately 0.5H: 1V. These cut slopes are <br />designed to achieve a factor of safety of 1.5 or greater as required by the Rules. Figure 4 -1 shows <br />maximum stable slope heights using the design method described above. Some slopes shown in the <br />permit drawings exceed the maximum allowable slope height based on the lowest cohesion value <br />used in the analysis. Additional geotechnical investigation and design or other slope stabilization <br />methods will be needed prior to haul road construction in these areas. The approach to establishing a <br />safe slope in such areas will include the following steps. <br />1) Investigate the road alignment to determine depth to bedrock. <br />a. If cut slope is in rock: <br />i. Redesign with 0.5H:1V slope to top of rock and benched 1.5HJV cut slope <br />from top of rock to ground surface <br />ii. Re- evaluate slope height to determine if it meets design requirements <br />iii. If design requirements are met, construct slope with the revised design <br />iv. If design requirements are not met, proceed to Step 2 <br />b. If cut slope is not in rock, proceed to Step 2 or Step 3 <br />2) Sample and test soil in slope area: <br />a. Determine new maximum slope height based on actual test data from soils in slope <br />area <br />b. If design requirements are met, construct slope as designed <br />PAMpls \06 CO \26 \06261003 MCC Refuse Pile Site Review & Permit \WorkFiles\Permit Application \Text \2010- 04- 19_RPE East Permit Application. doc17 <br />