2009-06-02_PERMIT FILE - C1982056A (4)

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minimize freezing problems. The existing transfer pipeline is approximately 7,300 feet long. Any future feed line for the water treatment ponds would be approximately 4,300 feet long. In conjunction with construction of the 6MN Mine Water Storage Reservoir, a valved connection was established on the existing transfer line, and a separate 6,000 foot transfer pipeline was constructed to the Reservoir to serve as a reservoir feed line. Supplemental control equipment was added to provide for operation of the valves and to allow remote shut-off of the submersible pump for both maintenance, and in the event of a reservoir level alarm. In the event that TCC decides to install a water treatment system at this location in the future, water from the sump will discharge to two ponds, each approximately 170 x 85 x 8 feet, within an area of approximately 300 x 250 feet. The design for the treatment ponds is presented in Exhibit 8C(1), EMD Treatment Pond Design. Approximately 5,550 cy of topsoil will be salvaged and stockpiled adjacent to this pond area. As shown in Figure 1, Exhibit 8C(1), an access road (loop) will be constructed to the treatment ponds. Approximately 740 cy of soil material will be salvaged from the short segments of road leading to the ponds. The soil will be windrowed to the side of the road and seeded with the topsoil stockpile stabilization seed mixture. Prior to discharging to the ponds, the mine water will be treated using the same methods used at the Fish Creek Dewatering Borehole to aid in the settling of suspended and dissolved materials. TCC's experience indicates that use of these methods to pre-treat the mine water in conjunction with settling ponds, is adequate to assure compliance with applicable water quality standards. A piping manifold or fittings and valves will allow selective discharge to the ponds to maximize their use and efficiency. An interior line between the two ponds will allow for flow between the ponds. A 15-foot wide road will encircle the ponds to provide for maintenance and repairs. An 8-inch discharge line buried approximately 4 feet deep will carry the discharge to Foidel Creek. A flow measuring device will be used to obtain the appropriate flow measurements. A 10 x 15 x 30 foot building will house the chemical feed system and control panels for the dewatering pump. The building will be constructed on a 10 x 3' x 0.5 foot concrete pad, as shown on Maps 17 and 18. Sediment control for the site will consist of seeding and (if necessary) mulching the topsoil stockpiles and cut and fill slopes, and use of an adjacent established vegetative filter. The SAE demonstration for this area is presented in Exhibit 8C, EMD Dewatering Treatment Facility. 6MN Mine Water Storage Reservoir (TR07-61) -The 6MN Storage Reservoir will be used to provide back-up storage for TCC's 10-Right Mine Dewatering Well, allowing the well to pump continuously at full capacity, providing buffer storage for pump maintenance or failure, and limiting the distance over which the mine water must be transferred. The 6MN Storage Reservoir is designed as a closed reservoir, with no discharge, and provision for adequate operating free-board to allow for storage of runoff from a small upslope drainage area. 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. Even though the 6MN Storage Reservoir has been designed and will be operated as a closed reservoir, a single open-channel emergency spillway has been incorporated into the design in compliance with applicable regulatory requirements for impoundments. Any discharge of stored mine or stormwater from the 6MN Storage Reservoir, will be directly to the mine water system, with no discharge through the emergency spillway to natural drainage. 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 (also refer to detailed Reservoir description on pages 2.05-45.6f through 2.05-45.8). 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. SMALL AREA EXEMPTIONS AND ALTERNATIVE SEDIMENT CONTROLS TCC has been granted several Small Area Exemptions (SAE'S) and/or approvals to utilize Alternative Sedimant Controls (ABC's) within the permit area. Effective drainage and sedimentation control in these areas will be achieved through the use of a number of individual or combined methods, including gravel-surfacing; erosion control fabric or materials; berms; contour furrows; sediment traps; rock check dams; vegetative filters; the use of silt fences, straw wattles, or straw bales; or other approved methods. Specific SAE/ASC practices are described in the following sections. TR09-66 2.05-82 04/ 11 /09