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are for a cohesion value that 90 percent of colluvium tests exceeded, based on a statistical analysis. <br />The maximum strength values used in the calculations are for a cohesion value that 10 percent of <br />colluvium tests exceeded. The results of the calculations for cut and fill slopes, assuming a factor of <br />safety of 1.5 for cut slopes and 1.3 for fill slopes, were plotted in a spreadsheet and are shown in <br />graphs presented in Figures 4-1 and 4-2. Wherever possible, slopes were constructed in accordance <br />with the maximum slope height and angle for the 10 percent material strength (90 percent of <br />colluvium samples tested stronger than design value). This limited the slope height to about 35 feet <br />for both cut and fill slopes that are constructed at a slope of 1.5H:1V. Where slopes could not be <br />constructed within these constraints, other slope stabilization measures, such as use of geotechnical <br />reinforcement (mechanically stabilized earth (MSE) slopes) or boulder walls, were used to establish <br />safe slopes. <br />The slope adjacent to Haul Road 1 required slope heights that could not be constructed in <br />conformance with the Taylor method. As a result, stabilization construction that included blanket <br />drains, horizontal drains, and slope reconstruction for this area was undertaken in 2011 and 2012. A <br />report that described the site conditions, improvements, and monitoring for the slope was submitted <br />to the CDRMS in May 2012 and revised in December 2012. A copy of the report is provided in <br />Appendix H. <br />4.7.3 Haul Road Surfacing <br />Haul roads outside of the waste rock pile footprint were surfaced with a total of 12 inches of <br />aggregate base, including 4 inches of Colorado Division of Transportation (CDOT) Specifications <br />703.03 Class 5 aggregate over 8 inches of CDOT Specifications 703.03 Class 3. Roadways within the <br />waste rock pile footprint may remain as an unfinished refuse material surface, but additional <br />surfacing materials may be placed on these roadways if needed to obtain adequate traction for safe <br />access by haul trucks. Typical roadway surfacing is shown on the permit drawings in Appendix D. <br />4.7.4 Other Design Considerations <br />Haul roads that are outside of the RPEE waste rock pile footprint were constructed with methods and <br />with erosion control measures to control erosion within the construction area. The extent of site <br />disturbance for haul road construction will be kept to a minimum. <br />24 <br />PAMpls\06 CO\26\06261003 MCC Refuse Pile Site Review & Permit\WorkFiles\Permit Application\2014 Revision\Exhibit 82 2014-05- <br />29.docx <br />