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- J <br />the bench. <br />o Underground coal waste constructed at a slope of 25 <br />- degrees from the toe to within 4 feet of the top of the <br />slope. <br />0 30 feet high, 60 feet wide berm constructed of coal waste. <br />o Four-foot depth of recompacted fill material placed over the <br />coal waste. <br />_ 0 10 feet high, 20 feet wide rock berm. <br />- The northern portion of the bench requires elimination of the toe <br />excavation and the construction of a 100-foot wide, 30-foot high <br />berm composed of recompacted fill material. The southern portion <br />_ of the bench requires replacement of the toe excavation with a <br />- sand and gravel type material, elimination of the berm and <br />- placement of recompacted fill material to a height of <br />approximately 30 feet above the toe of the slope. The <br />requirements of the sand and gravel material are that it have an <br />effective phi angle of 36 degrees and a unit weight of 110 pounds <br />per cubic foot or greater. <br />Specific cross-sections, providing information on final designs, <br />are shown in the stability cross-sections represented by Figures <br />7 and 8. A detailed plan of the mine bench showing the final <br />• design configuration is provided on Figure 5 and contours <br />representing the final detailed plan and subsurface drainage <br />details are presented on Figure 9. <br />19 <br />