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Placement and Compaction <br />The coal mine waste material will be hauled to the refuse disposal area where it <br />will be spread in maximum lifts of 24 inches and compacted. The top of the pile <br />will be sloped to the south. <br />Coal mine waste will be placed and compacted to 90 percent of the maximum <br />dry density to prevent spontaneous combustion and to provide the strength <br />required for stability of the refuse pile. Dry densities will be determined in <br />accordance with AASHTO T99-74. The placing and spreading of the coal mine <br />waste will be started at the lowest point of the foundation. The coal mine waste <br />will be keyed into the natural ground. Materials will be spread in approximately <br />horizontal lifts no more than 24 -inches thick, and such lifts made uniformly over <br />long stretches. Each lift will be moistened or dried to a uniform moisture content <br />suitable for maximum compaction. Compaction will be carried to the edge of the <br />fills so that the final slopes are firm. The fill will be shaped and benches <br />(terraces) constructed as shown on Map 15 and in accordance with the design <br />parameters listed above. <br />When native material is available, blending of wet coal mine waste with native <br />material may prove to be an effective moisture content management strategy. <br />During the initial phase of gob pile #3, wet gob was blended with native material <br />to achieve a desirable moisture content for placement and compaction. Results <br />of triaxial testing of the blended material appear in HBET's stability analysis <br />dated July 15, 2014. <br />Compaction tests will be taken at a frequency and location of not less than one <br />per every other layer, at random locations across the pile. Test locations and <br />results will be reported to the Division in the appropriate construction reports. <br />Coal mine waste materials from activities located outside of the permit area, <br />such as those activities at other mines or abandoned waste piles, will not be <br />placed in the coal mine waste bank unless approved by the Division. <br />Volume XI <br />TR -114 - 9 - 08/17 <br />