2010-06-04_PERMIT FILE - C1982056A (9)

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water system, with no discharge through the emergency spillway to natural drainage. While it will not be utilized during normal operations or under design storm conditions, the open - channel spillway, and the lower portion of the stormwater diversion channel are designed to safely pass the peak discharge (approximately 125.5 cfs), and the total runoff, respectively from the design storm event. On the edge of the Reservoir, near the embankment, a pump platform will be constructed, with a suspended 50 HP high- capacity submersible pump, pumping mine water from the Reservoir at a rate of up to 1,000 gpm to the Million - Gallon Tank at 6MN (MR06 -210), which is set -up to gravity -feed to the mine water system through the existing mine water utility borehole. A pad and short (130 feet) light -use road segment will provide access for inspection and maintenance. The approximately 1,400 foot pipeline from the 6MN Reservoir to the Million - Gallon Tank and utility borehole will also be 10 -inch HDPE pipe buried to a depth of approximately six feet within the previously disturbed 6MN road right -of -way. Pipeline construction disturbance will be reclaimed concurrently with pipeline installation, with backfilling, soil replacement, and reseeding using the standard rangeland seed mixture. In order to assure adequate and consistent water quality for the feed to the mine water system, the 6MN Mine Water Storage Reservoir installation will include some basic water treatment measures, potentially including one or more aerators, floating baffles within the pond, and a simple filtration system in the discharge pipeline between the Reservoir and the Million - Gallon Tank. If it is determined that additional treatment measures are necessary, any significant modifications will be addressed by a future revision. TCC will remotely monitor and control reservoir water level, and mine water discharge to and from the 6MN Storage Reservoir, to maintain the water level at or below design storage capacities, and to maintain the design freeboard, at all times. Water level and pump control interfaces will provide for integrated control of pumping systems to balance inflow and discharge and shut -off the deep well pump if the pond level reaches a certain pre -set threshold level(s), and an integrated alarm system will remotely notify the operator of any system failure, malfunction, or water level concern. These controls will also assure that adequate storm -water storage capacity is • maintained at all times. Electrical power for the 6MN Reservoir discharge pump, aerators, and control systems will be provided by a short (approximately 300 feet) distribution line from the existing substation at the 6MN Shaft pad. Construction of this short line segment will require the installation of 3 powerpoles. Also, a short light -use road, approximately 300 feet in length, will be constructed to the pond pump- station from the existing 6MN Shaft pad access road. The location, configuration, and components of the 6MN Mine Water Storage Reservoir installation are shown on Map 24 (sheet 2 of 3), Surface Facilities and Freshwater Systems. Related design information is provided in Exhibit 490, 6MN Mine Water Storage Reservoir — Design Drawings, including a design stability analysis for the pond embankment. Because the proposed Reservoir storage volume is greater then 20 acre -feet, design and compliance documentation have also been submitted to the Mine Safety and Health Administration (MSHA) for review and approval. 18 -Left Ventilation Shaft (TR 09 -66) As mine development proceeds to the west in the Western Mining District (WMD), the distance from existing mine ventilation shaft and fan installations will increase to the point where additional intake and exhaust ventilation shafts are necessary to maintain effective ventilation of active mining areas. In order to minimize surface disturbance and simplify operation, the new intake and exhaust shafts will be established at the same location. The proposed new ventilation shafts will be located in close proximity to Routt County Road 27 in the NW' /SWI/ Section 23, TSN, R87W on a shallow slope near the crest of a small ridge in an area of open pastureland, as shown on Map 23. Development, construction, and installation of the ventilation shafts and associated fan and ancillary facilities will involve the following sequential activities, as briefly described in the following sections and shown on the design drawings provided in Exhibit 49R: i Completion of environmental and engineering investigations • Placement of disturbed area markers • Temporary drainage and sediment control measures • Recovery and stockpiling of available soil materials TR06 -57 2.05 -45.6h 07/02809