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• Temporary erosion control measures (ditches, berms, straw dikes, silt fence) will be utilized during <br />embankment construction to minimize sedimentation and erosion until permanent control measures <br />can be established. Immediately upon wmpletion, measures will be taken to stabilize all embank- <br />ments with vegetation cover or other means as approved by the regulatory authority to minimize <br />erosion. Where a vegetation cover is used, consideration shall be given to providing an appropriate <br />growth medium. <br />Drainage. Each haul road not within the mine pit areas will be designed, constructed and maintained to <br />have adequate drainage using ditches and culverts to safely convey the peak runoff from a 10-year, 24-hour <br />precipitation event while maintaining a minimum of 0.3 feet of freeboard to the top of the road embankment <br />(see Exhibit 13-2 for ditch locations and Exhibit 13-10 for typical details of road drainage structures). <br />Drainage ditches will be placed at the toe of all cut slopes formed by the construction of haul roads. Water <br />will be intercepted before reaching a large fill and drained safely away in accordance with the requirements <br />of Rule 4.03.1. Water from a fill will be released below the fill through conduits or in adequately lined <br />channels and will not be discharged onto the fill. <br />When haul road drainage ditches discharge onto open tercain, a number of measures will be taken to <br />minimize erosion including revegetation, straw dikes, and riprap. When the road ditch discharges onto a <br />disturbed area, the terrain will be revegetated or lined with riprap, if necessary, to control runoff and <br />• erosion. Temporary measures to reduce erosion (straw dikes, containment ditches, silt fence, etc.) will be <br />employed while the area is undergoing revegetation. <br />SCC typically constructs ditches on the inside of roadway cuts and safety berms for drainage. Atypical V- <br />ditch section is a minimum of two feet deep with side slopes 1.5H:1V or flatter. As most road cuts are into <br />resistant bedrock-type material, ditches normally do not require lining. Culverts are sized and installed to <br />minimize the runoff volume conveyed in each ditch. Culverts and ditches are typically designed using <br />SEDCAD to predict the peak runoff; Monolog's equation or the SEDCAD channel utility are used to <br />determine the peak velocity and flow depth (see Attachment 13-1, General Hydrology Design Methods). <br />Attachment 13-6, Ditch Calculations, presents the ditch designs. Table 13-3, Summary of Watershed <br />Parameters and Design Characteristics for Haul Road Ditches Including Mine Entrance Haul Road, <br />summarizes the ditch designs for the mine area haul roads. Table 13-4, Summary of Watershed <br />Parameters and Design Characteristics for Road Ditches along the Tie-Across Haul Road, presents <br />the designs for the Tie-Across Haul Road ditches. Haul Roads G, H, I, J, K and L utilize typical ditch <br />cross sections as depicted on Exhibit 13-10. Attachment 13-6A, General Design for Haul Road Ditch <br />Porous Rock Check Dams, contains general designs for the porous rock check dams that are <br />incorporated into She Mine Entrance Haul Road and Haul Road G ditches. These check dams assist in <br />minimizing the amount of sediment reaching some of the culvert outlets along these roads. <br />If the ditch is not stable, then a larger ditch section is used and/or adequately lined in order to comply with <br />applicable regulations, <br />PR-05 19 Revised 01/06 <br />