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3) Embankment slopes not demonstrated to be stable in Step 1 or Step 2 will be stabilized with <br />other methods such as retaining walls, soil nailing, or other technology. <br />4.7.3 Haul Road Surfacing <br />Haul roads will be surfaced with a total of 12 inches of aggregate base, including 4 inches of <br />Colorado Division of Transportation (CDOT) Specifications 703.03 Class 5 aggregate over 8 inches <br />of CDOT Specifications 703.03 Class 3 <br />4.7.4 Other Design Considerations <br />Haul roads will be constructed with methods and with erosion control measures to control erosion <br />within the construction area. The extent of site disturbance for haul road construction will be kept to <br />a minimum. <br />Haul road ditches will be used to divert clear water away from the refuse pile in areas west of the <br />refuse pile footprint. Water will drain in the road ditches and will discharge in a controlled manner <br />to natural ground adjacent to westerly switchbacks, then over natural ground to Sylvester Gulch. <br />Drainage flows will typically be small in these areas due to the limited size of drainage areas above <br />and between the roads, so impacts to the road condition and traffic flow will be minimal under most <br />conditions. Should a large storm result in erosion and/or large accumulations of sediment at the <br />switchback discharge points, any erosion damage will be repaired and sediment control structures <br />cleaned and maintained. <br />Haul road driving surface width is based on MCC's truck fleet that will be used for refuse haulage. <br />The current fleet consists of Caterpillar 730 model articulated trucks, with an operating width of 9 <br />feet, 6 inches. MCC is considering upgrading to the 740 model, with an operating width of 11 feet, 2 <br />inches. Assuming that haul roads will be primarily one -way roads with turnouts for passing, using <br />MSHA guidance of vehicle width plus one -half vehicle width on each side of the lane, haul road <br />width was determined to be a minimum of 19 feet for the 730 model and approximately 22.5 feet for <br />the 740 model. The design road section driving surface was rounded up to 24 feet in the drawings. <br />4.8 Construction Inspection <br />The refuse pile will be inspected during construction and during placement of coal refuse materials. <br />Revised March 19, 2010 1 <br />Revised April 2, 2010 Ag S <br />2 <br />P:\Mpls \06 CO \26 \06261003 MCC Refuse Pile Site Review & Permit \WorkFilesTermit Application \Text\2010- 04- 19_RPE East Permit Application.doc19 <br />