1992-10-20_REVISION - M1977348 (4)

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• North Poudre Irrigation Company's Monroe Gravity Canal. Although this flow was not diverted, a concrete pipe was installed in the drainage to prevent possible water leakage into the A-band quarry. Since both the Niobrara formation and the underlying Codell sandstone are virtually impermeable, rain and snow falling into the A-band quarry accumulate into permanent pools which fluctuate with the amount of precipitation and the surface area exposed to evaporation. The deeper E-band quarry also accumulates precipitation, but this interferes with operations and is drained to a sump and then pumped over the overburden piles to the east to drain into the Water Supply and Storage ditch. ~@ ~. Area ~ 2g Worked ~t bRY 9Jl@ Time The chemical requirements of the cement manufacturing pro~:ess require a blend of several raw materials from the quarrie;~. This necessitates simultaneous quarrying at several faces. And, since the reclamation of a large part of the quarry twill be accomplished by first filling the quarry cut with kiln dust, then covering with overburden and any topsoil available, the reclamation will be phased by the volume o kiln dust available. The new (post-1981) plant demand, at design capacity, will be approximately 600,000 tons per year of quarry material, or approximately 325 feet advance of the entire E-band cross-- section. This will result in an average of 8 to 10 new ac:res being mined per year. The mined area will then stay open until the kiln dust disposal operation advances to the area, whereupon it will be filled, with overburden cover following. floerational Time-table f~ Minina and Reclamation Past operations have quarried the A-band to its present economic limit. The A-band quarry lhas been divided into 7 areas. Al is presently being filled with inert silica sludge from the adjacent Colorado Lien silica plant in preparation for reclamation. The sludge is transported to the site b}~ water, then the water is decanted off and recycled to the silica plant. At the termination of this operation, the sludge in the fill will be dewatered and the fill covered and reclaimed with material from the adjacent overburden pile. A2 is presently the site of the plant CKD landfill. This landfill will also be covered and reclaimed with material from the overburden piles on the west side of the cut where necessary. Since these overburden piles are pre-law, only those portions that are redisturbed will be graded back to a • maximum 2:1 slope and seeded. It is estimated that this area still has a fill life of 9 years. At that time the CKD landfill will be moved to E1 which should be quarried out by 16