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Mountain Coal Company Exhibit 69 <br />West Elk Mine Slope Stability Improvements <br />'~ other surface irregularities. Any excess material cut from the trench drains will be <br />utilized for regrading the slope. <br />This work will occur within previously disturbed azeas; therefore, no topsoil salvage will <br />be necessary. These drains will remain upon final reclamation. The trench drain <br />construction and slope regrading will be completed first, and depending on the <br />effectiveness of this construction, the retaining wall, as discussed below, may be <br />necessary to "hold" the Landing #2 light-use road. <br />Retaining Wall <br />A retaining wall will be constructed, if necessary, along the outside edge of the Landing <br />#2 light-use road above the Sylvester Gulch Substation. The location of the wall is <br />shown on Figure 1. The retaining wall will be constructed of 27 steel piles anchored 10 <br />feet into bedrock. The steel piles will be placed on an 8 foot spacing with 8-inch by fl- <br />inch timber lagging spanning between the piles from bedrock elevation to the elevation of <br />the Landing #2 light-use road. The timber lagging will be exposed. Figure 2 shows the <br />construction details for the wall. The altemate section as shown on this figure will only <br />be utilized if during construction MCC encounters a deeper colluvium layer than was <br />indicated by drilling information. If a deeper colluvium layer is encountered, the <br />colluvium will be excavated below the 16-foot level and replaced with low strength <br />concrete, to improve the strength and stability of the mass behind the wall, and to ensure <br />• that the wall will function as designed. <br />The retaining wall will also be constructed within previously disturbed areas; therefore, <br />no topsoil salvage will be necessary. MCC will remove the portion of the retaining wall <br />that is above bedrock upon final reclamation. Any excess soil material cut to prepaze for <br />the wall will be included with the regrading work associated with the trench drain project <br />described above. Approximate material quantities for this work, assuming that the <br />altemate piles will be required (i.e. assuming worst-case), include: 761 linear feet (LF) of <br />steel pile, 7600 LF of 8-inch by 8-inch timber lagging, 31 CY of concrete grout, 778 CY <br />of lean concrete backfill, and 208 LF of guardrail. Although only a portion of the wall <br />will be removed upon final reclamation, these quantities aze based on entirely removing <br />the 27 piles. <br />• <br />z <br />a5 <br />