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succeeding layer is placed. Successive layers will be compacted evenly by routing dozers, <br /> trucks and scrapers over the entire width of the embankment. This procedure will be <br /> continued until no visible horizontal movement of the embankment material is apparent. <br /> Embankment layers will be compacted to a minimum of 90 percent of Standard Proctor density <br /> or as directed by the engineer to ensure that the embankment is adequate to support the <br /> anticipated volume of traffic and weight and speed of vehicles to be used. <br /> Material will be placed in an embankment only when its moisture content is within <br /> acceptable levels to achieve design compaction. <br /> Temporary erosion control measures (ditches, berms, straw dikes, silt fence) will be <br /> utilized during embankment construction to minimize sedimentation and erosion until <br /> permanent control measures can be established. Immediately upon completion, measures will <br /> be taken to stabilize all embankments with vegetation cover or other means as approved by <br /> the regulatory authority to minimize erosion. Where a vegetation cover is used, <br /> consideration shall be given to providing an appropriate growth medium. <br /> Drainage. Each haul road not within areas disturbed by mining and reclamation activities <br /> will be designed, constructed and maintained to have adequate drainage using ditches and <br /> culverts to safely convey the peak runoff from a 10-year, 24-hour precipitation event <br /> while maintaining a minimum of one foot of freeboard to the top of the road embankment <br /> (see Exhibits 13-4 and 13-5 and for general locations and Exhibit 13-20 for typical <br /> details of drainage structures). <br /> Drainage ditches will be placed at the toe of all cut slopes formed by the construction of <br /> haul roads. Water will be intercepted before reaching a large fill and drained safely <br /> away in accordance with the requirements of 4.03.1. Water from a fill will be released <br /> below the fill through conduits or in adequately lined channels and will not be <br /> discharged onto the fill. <br /> When drainage ditches discharge onto open terrain, a number of measures will be taken to <br /> protect the terrain from erosion. When the drainage discharges onto a disturbed area, the <br /> area will be revegetated to control runoff. In an area where revegetation would not be <br /> sufficient to control erosion, the area will be rip-rapped. Temporary measures to reduce <br /> erosion will be employed while the area is undergoing revegetation such as straw dikes, <br /> containment ditches, etc. <br /> 13-16 Revised 04/11/88 <br />