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Each layer of the embankment will be completed, leveled and compacted before the <br />• 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 fs 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 access road not within areas disturbed by mining and reclamation <br />activities 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 <br />precipitation event while maintaining a minimun of one foot of freeboard to the top of the <br />road embankment (see Exhibit 13-20 for typical 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 discharged <br />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 riprapped. Temporary measures to reduce <br />erosion will be employed while the area is undergoing revegetation such as straw dikes, <br />• containment ditches, etc. <br />13-26 Revised 04/11/88 <br />