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reduce erosion (straw dikes, containment ditches, silt fences, etc) will be employed while the area is <br />undergoing revegetation such as straw dikes, containment ditches, etc. SCC typicafly constructs ditches on <br />the inside of roadway cuts for drainage. Atypical V-ditch section is a minimum of two feet deep with side <br />slopes 2H:1 V or flatter. As most road cuts are into resistant bedrock-type material, ditches normally do not <br />require lining. Culverts were designed and installed to minimize the runoff volume conveyed in each ditch. <br />Culverts and ditches will typically be designed using SEDCAD+ to predict the peak runoff and Manning's <br />equation to determine the peak velocity and Flaw depth (see Attachment 13-1). <br />If the ditch is not stable, then a larger ditch section will be used andlor adequately line the ditch in order to <br />comply with applicable regulations. <br />Drainage from access roads within the areas disturbed by mining and reclamation activities (see Exhibit 13- <br />2) will be constructed to meet the requirements of Rule 4.05,2 and such access roads will at a minimum be <br />constructed and maintained to minimize erosion of the disturbed area. Access road drainage ditch <br />designs are presented in Attachment 13-6. Plan and profiles are shown on Exhibit 13-25,2, Postmine <br />Oil Well Access Road Plan and Profile and, Exhibit 13-26.1 A, Ridgeline Access Road As-Built <br />Erosion control measures to be used singly or in combination include but are not limited to: <br />a. Stabilizing all exposed surface areas to promote a reduction in the rate and volume of runoff; <br />b. Using straw dikes, riprap, check dams, berms, geotextile materials, mulches, vegetation <br />sediment filters, contour furrows or other measures that reduce overland flow velocity, reduce <br />runoff volume, or trap sediment; or <br />c. Such other measures to minimize erosion resultant siltation and disturbance to the prevailing <br />hydrological balance. <br />Surfacing. See Exhibit 13-10 for typical detail. <br />Culverts. Each access road will be designed, constructed, and maintained to have adequate drainage using <br />ditches and culverts to safely convey the peak runoff from a 10-year, 24-hour precipitation event to sediment <br />ponds before being released from the permitted area (see Exhibit 13-10 for typical details of road drainage <br />structures). Culvert locations are shown on Exhibit 13-2. Access road culvert designs are presented <br />in Attachment 13-7. <br />Culverts will be installed to avoid plugging or collapse and to avoid erosion at the inlets and outlets. Riprap <br />will be installed as necessary to reduce the exit velocity. The minimum width will be the width of the natural <br />downstream channel. The riprap will be sized in the feld by SCC's project engineer based on the "as-built" <br />slope of the culvert and final configuration of the exit channel slope area. The sizing shall be based on the <br />Federal Highway Administration's HEC No. 11 "Use of Riprap for Bank Protection" or other standard <br />methods. All culverts will have a minimum cover of 12 inches. Culverts and drainage ditches will be <br />maintained periodically to prevent accumulation of debris on the culverts inlets and outlets. <br />PR-05 34 Revised 01/06 <br />