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Material containing, by volume, less than 25 percent of rock larger than 6 inches in greatest dimension • <br />will be spread by scrapers or dozers in successive uniform layers not exceeding 12 inches in thickness <br />before compaction. <br />When the material for an embankment consists of large size rock, broken stone, or fragmented material <br />that makes placing it in 12 inch layers impossible, the embankment will be constructed in uniform <br />layers not exceeding the thickness of the average size of the rock used, but layers will not exceed 36 <br />inches. Rock will be distributed by blading or dozing in a manner that will ensure proper placement in <br />the embankment, so that voids, packets and bridging will be reduced to a minimum. The final layer will <br />meet the requirements of 4.03.113)Id)Iv). <br />Each layer of the embankment will be completed, leveled and compacted before the succeeding layer is <br />placed. Successive layers will be compacted evenly by routing compaction equipment over the entire <br />width of the embankment. This procedure will be continued until no visible horizontal movement of the <br />embankment material is apparent. Embankment layers will be compacted to a minimum of 90 percent <br />of Standard Proctor density or as directed by the engineer to ensure that the embankment is adequate <br />to support the 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 acceptable levels to • <br />achieve design compaction. <br />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 can <br />be established. Immediately upon completion, measures will be taken to stabilize all embankments with <br />vegetation cover or other means as approved by the regulatory authority to minimize erosion. Where a <br />vegetation cover is used, consideration shall be given to providing an appropriate growth medium. <br />Drainage. Each haul road not within areas disturbed by mining and reclamation activities will be <br />designed, constructed and maintained to have adequate drainage using ditches and culverts to safely <br />convey the peak runoff from a 10-year, 24-hour precipitation event while maintaining a minimum of 0.5 <br />feet of freeboard to the top of the road embankment (see Exhibit 13-2, Surface Water Control Plan, for <br />general locations and Exhibit 13-9, Typical Haul Road Details, for typical details of drainage structuresl. <br />Please refer to Attachment 13-7, Haul Road Ditch Designs, for ditch requirements for Haul Roads A and <br />B and Attachment 13-12, Drainage and Sediment Control Plan, for the design details of all new <br />hydrologic structures. • <br />16 Revised 7/99 <br />