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The Washplant Feed Conveyor discharges to a surge bin, with water added at the transfer point. Feeders draw from
<br />the surge bin to feed the coal to a series of screens, heavy -media cyclones (using a slurry of magnetite and water to
<br />separate the coal from the heavier refuse material), classifying cyclones, wash screens, and centrifuges, producing
<br />•both a coarse and fine coal product, which are combined and discharge to the Overland Conveyor. Coal refuse is
<br />separated from the coal stream in the cyclones, with the coarse refuse passing over screens to drain and then to the
<br />Coal Refuse Conveyor, and the fine refuse being transferred to the Thickener to reduce water content. The
<br />Washplant will require approximately 600 gpm of make -up water, to address losses to the coal product, coarse
<br />refuse, and fine refuse streams (note that most of the water from the fine refuse stream is recovered and recycled to
<br />the Mine water supply system, which include the washplant feed water). The coal preparation circuit also includes
<br />the magnetite recovery and recycling system, and a water filtration and recycle system, to minimize water use
<br />requirements. The coal preparation equipment, along with associated chute -work, and control and monitoring
<br />systems, are housed in the Washplant Building, a steel frame building with steel siding and roof (55 x 125 x 80 feet
<br />high), which sets directly over the Overland Conveyor. The building sets on a reinforced concrete slab (58 x 128 x
<br />1 foot thick).
<br />The Coal Refuse Conveyor (48 -inch belt w /500 tph capacity), transfers coarse coal refuse from the Washplant to a
<br />Refuse Bin. The Refuse Bin is used to load trucks, which haul the coal refuse material to the existing permitted
<br />Coal Refuse Disposal area. The Coal Refuse Conveyor is designed to handle current requirements of 500 tph, as
<br />well as possible future system expansion. The Refuse Conveyor is supported by two steel support bents, and
<br />utilizes the typical conveyor construction. The conveyor bents set on reinforced concrete caissons, as previously
<br />described. The Refuse Bin is a steel frame building (30 x 30 x 50 feet high) with steel siding and roof which
<br />supports a 200 -ton pre- fabricated steel surge bin and contains minor chute -work and a dust collection system. The
<br />Refuse Bin sets on a reinforced concrete slab floor.
<br />The Washplant II Thickener, which is used to partially dewater the fine coal refuse, is a reinforced concrete tank
<br />approximately 50 feet in diameter, and. 12 feet high. A flocculating agent is introduced into the tank, and a high -
<br />efficiency underflow system mixes the flocculant with the fine refuse stream, causing the refuse particles to
<br />•agglomerate and settle from suspension. The decant water discharges through a filter and is recycled to the
<br />Washplant. The fine coal refuse slurry normally discharges through discharge pipelines connecting to 8 -inch drop -
<br />boreholes and associated underground piping systems, which carries the slurry to areas of sealed underground mine
<br />workings. Underground, the water decants from the fine refuse slurry and flows downgradient to sumps where a
<br />pumping system is used to recover and recycle the water. In order to address emergency mine dewatering
<br />requirements, slurry may be temporarily diverted to an incised basin within the Area 1 Pit permitted mine refuse
<br />disposal area, with decant of clarified water to the Area 1 Pit Mine Water Storage Reservoir. Coal fines that
<br />accumulate in this temporary basin will be allowed to dry -out and will then be transferred to the permanent Coal
<br />Refuse Disposal area.
<br />TCC completed thickener underflow boreholes in both the SWMD and the EMD, and installed thickener underflow
<br />pipelines to convey fine coal refuse, as a slurry, from the washplants to these locations. The 1MN Thickener
<br />Underflow Borehole is located to the west of the previous CYCC Office Building (Brown Palace) location, along
<br />the existing light -use road, and extends approximately 310 feet into the sealed and abandoned mine workings in the
<br />SWMD. The 6RT Thickener Underflow Borehole installation is located southeast of the intersection of Routt
<br />County Roads 27 (RCR27) and 33 (RCR33), on the north side of Foidel Creek and the Twentymile Mine railroad
<br />spur. The Thickener Underflow Borehole extends approximately 540 from the surface into the sealed EMD mine
<br />workings. An existing light -use road extends approximately 250 feet from RCR33 to this location. At both
<br />locations, a drill -pad and required drainage structures were constructed. Buried thickener underflow pipelines were
<br />installed between the existing washplant facilities and the two thickener underflow boreholes. The locations of both
<br />the thickener underflow boreholes and the associated pipelines are shown on the Surface Facilities and Freshwater
<br />Systems Map, Map 24 (1/4).
<br />Installation of the thickener underflow boreholes involved placement of construction erosion controls (silt fence
<br />•and/or straw wattles), removal and windrowing of available soil materials from pad areas and the road margins
<br />(6RT Borehole only), grading to establish level drill -pads and improve the existing light -use road (6Rt Borehole
<br />only), placement of gravel as surfacing for the light -use road, excavation of temporary cuttings pits on the drill -
<br />pads, drilling and casing of the boreholes, and installation of protective access manholes. On completion of drilling
<br />and casing operations, the cuttings pits were allowed to dry -out, material excavated from the pits was replaced and
<br />TRI l -77 2.05 -32.3 07/20/11
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