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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 discharges through a HDPE double walled pipeline network where it is then
<br />dropped down boreholes which carry the slurry to areas of sealed underground mine workings. Underground,
<br />water decants from the fine refuse slurry and flows downgradient to sumps where a pumping system is used to
<br />recover and recycle the water. In order to address emergency mine dewatering requirements, slurry may be
<br />temporarily diverted to an incised basin within the Area 1 Pit permitted mine refuse disposal area, with decant of
<br />clarified water to the Area 1 Pit Mine Water Storage Reservoir. Coal fines that accumulate in this temporary basin
<br />will be allowed to dry -out and will then be transferred to the permanent Coal Refuse Disposal area.
<br />TC has completed or will complete thickener underflow boreholes in the SWMD, WMD, and the EMD, and thickener
<br />underflow 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 the
<br />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 County
<br />Roads 27 (RCR27) and 33 (RCR33), on the north side of Foidel Creek and the Twentymile Mine railroad spur. The
<br />Thickener Underflow Borehole extends approximately 540 from the surface into the sealed EMD mine workings. An
<br />existing light -use road extends approximately 250 feet from RCR33 to this location. The 7RT Thickener Underflow
<br />Borehole installation is located east of both the intersection of Routt County Roads 27 (RCR27) and 33 (RCR33) and
<br />the 6RT Borehole, on the north side of Foidel Creek and the Twentymile Mine railroad spur. The 7RT Thickener
<br />Underflow Borehole will extend approximately 850 feet from the surface into the sealed EMD mine workings. The
<br />2MN Thickener Underflow Borehole installation is located near the north edge of the existing Mine Facilities Area,
<br />between the existing Weld Shop and the Twentymile Railroad Spur and is accessed by a short (550 feet) access road
<br />from the existing mine road. The 2MN Thickener Underflow Borehole extends approximately 150 feet from the
<br />surface into the existing active 2MN No. 6 Mine Entry. From this location, the coal slurry is piped underground
<br />approximately 2,650 feet and 3,850 feet, respectively, to horizontal boreholes into the sealed 7 -Right and 8 -Right
<br />Panels in the Eastern Mining District (EMD).
<br />An additional thickener underflow borehole was added in the WMD in 2017. The 12 -Left Thickener Underflow
<br />Borehole is located off RCR27 just east of the intersection with County Road 37 on the north side of the road. The
<br />borehole extends into the WMD mine workings approximately 1,260 feet in the 12 Left Irby Panel. In 2018 four
<br />TRI 8-90 2.05-32.4 04/05/18
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