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and 571,600 cubic yards of suitable cover material will need to be recovered and replaced during the life of the
<br />CRDA Expansion. Soil and cover material handling operations are summarized by Table 49A, Soil Stockpile
<br />Summary, and in Exhibit 26C. Both soil and cover material stockpiles will be placed, graded, and stabilized to
<br />prevent loss or contamination of these materials, and to minimize erosion potential. Potential runon and runoff
<br />from the piles will be controlled by a closed system of ditches and berms, and the piles will be stabilized by seeding
<br />with a rapid - germinating temporary cover seed -mix (refer to Table 54, Cropland Seed Mix). Soil stockpiles will be
<br />posted with identifying signage, which will be maintained so long as material remains in the stockpile(s).
<br />Construction of the Coal Refuse Haulroad will proceed simultaneously with soil and cover removal operations for
<br />the refuse toe bench. The proposed haulroad will be approximately 2,300 feet long, with a traveled surface
<br />approximately 30 feet wide. Following soil material removal from the road alignment, the road footprint will be
<br />scarified and cut/fill operations will establish the general road configuration, as shown in the design documentation
<br />provided in Exhibit 26C, Coal Refuse Disposal Area Expansion Designs. Fills will be placed and compacted in
<br />uniform lifts of 6 -8 inches. The road surface will consist of approximately 6- inches of well - graded aggregate base,
<br />overlain by approximately 18- inches of pit run road base materials, compacted to 95 percent of maximum dry
<br />density. Road drainage will be addressed by designed ditches and culverts, sized to safely pass the runoff from the
<br />10 -year, 24 -hour storm event. Design documentation and the required P.E certification for road designs are
<br />presented in Exhibit 26C, Coal Refuse Disposal Area Expansion. The Coal Refuse Haulroad will provide for
<br />material haulage from the Coal Refuse Hopper(s) to the CRDA Expansion area. Haulage within the CRDA
<br />Expansion area, including haulage on benches, will occur on temporary roads established within the CRDA
<br />footprint and typically on established refuse fill areas.
<br />Following soil material removal, construction will begin on both the perimeter drainage control ditches and the
<br />CRDA toe drain. Because the CRDA Expansion will be constructed in phases, initial perimeter ditches will be
<br />constructed as temporary ditches, designed to safely pass the runoff from the 10 -year, 24 -hour storm event.
<br />Permanent perimeter ditches have been designed and will be constructed to safely pass the peak flows from the
<br />100 -year, 24 -hour design storm event. In order to control flow velocities and facilitate vegetative reestablishment
<br />in the permanent perimeter ditches, temporary rock check -dams may be constructed in these ditches in accordance
<br />with the design parameters previously outlined for the existing CRDA.
<br />Because infiltration through the pile to the CRDA Expansion foundation area would occur gradually over time,
<br />regardless of storm event, the toe drain has been designed based on the 10 -year, 24 -hour precipitation event. The
<br />toe drains primary purpose is to prevent any significant build -up of hydrostatic pressure within the pile, which
<br />could affect pile stability. Based on design calculations, the required toe drain would consist of durable 9 -inch rock
<br />with a cross - sectional area of approximately 50 square feet, enclosed by graded cover material to minimize the
<br />potential for fines infiltration and plugging. A minor drainage design modification, incorporated during the initial
<br />construction phase, will shift the northern end of the toe drain approximately 120 feet to the east, allowing the toe
<br />drain to discharge to the Area 1 Pit rather than Sedimentation Pond D. This minor design modification will allow
<br />for use of any drainage in the mine water system, and provide for better control of the water relative to mixing and
<br />water quality, while not affecting the stability of the pile.
<br />Drainage from the intermediate pile benches and the surface of the pile (both during construction and on
<br />completion) will be controlled by sloping benches and the pile surface away from the outslope, with the benches
<br />connecting into the perimeter drains along the margins of the pile. All drainage structures will route drainage to
<br />existing Pond D, which will continue to operate in compliance with applicable effluent standards. Designs for
<br />drainage structures associated with the CRDA are presented in Exhibit 8EE — Coal Refuse Disposal Area
<br />Expansion — Drainage Designs.
<br />During Phase I of the CRDA expansion, the upper perimeter ditch segments were not necessary, since surface
<br />drainage from upland areas could flow through existing channels and reach the base of the CRDA expansion area.
<br />During Phases II and III of the CRDA expansion, however, these channels will be constructed to route natural
<br />drainage around the CRDA perimeter. With completion of Phase I of the CRDA Expansion and the associated road
<br />access, it has become obvious that minor changes in the overall drainage configuration would be appropriate. In
<br />addition, planned road and drainage modifications to accommodate the planned future Sage Creek coal haul will
<br />result in other minor drainage changes. Specifically, TC proposes to eliminate Culvert RDA -7 -2, since the
<br />TR12 -80 2.05 -97.4 09/04/12
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