2009-03-04_REVISION - C1982056 (2)

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over which the mine water must be transferred. The 6MN Storage Reservoir will be 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. The 6MN Mine Water Storage Reservoir will be constructed south of the current 6MN Shaft pad and northwest of the NW Mains Ventilation installation. The reservoir embankment will be an earthen dam constructed of suitable fill material excavated from the reservoir basin and placed and compacted consistent with engineering design specifications and construction recommendations. The engineering designs will be based on site geotechnical investigations, which included drilling of six, 4-inch hollow-stem auger test holes; examination and testing of soil samples; placement of 1.5-inch slotted PVC pipe in two of the auger holes to measure water levels (piezometers); and excavation of seven shallow (6-11 feet in depth) test pits. The location of the 6MN Mine Water Storage Reservoir geotechnical investigations is shown on Map 24 (sheet 2 of 3), Surface Facilities and Freshwater Systems, and by the attached drawing, which will be inserted in Exhibit 490, 6MN Mine Water Storage Reservoir - Design Drawings Temporary and Permanent Shaft Heater Installation (MR08-227, MR09-234) It was necessary to install temporary shaft heaters during winter 2007/2008 to address severe icing conditions within the shaft that had the potential to interfere with operation of the 6MN Emergency Escape Hoist. TCC initially installed two portable skid-mounted propane air heaters (15' long, 7' wide, and 7.5' high) on the existing 6MN Shaft Pad (located adjacent to and immediately west of the Escape Shaft Hoist-House (see MR07-218) approximately 50' from the shaft opening), and connected them to a portable propane tank, the existing electrical lines, and to the shaft opening with pre-fabricated vent tubing. -1.; Based on the performance of the temporary shaft heaters during winter 2007/2008, TCC determined that additional heat output would be needed, both to prevent icing and to provide an adequate flow of warm ventilation air during the winter months. Four additional temporary shaft heaters were installed, along with a larger propane supply tank to meet immediate needs during early winter 2008/2009, and four larger permanent shaft heaters were ordered. On delivery of the permanent shaft heaters, TCC will proceed with construction of concrete pads for both the permanent shaft heaters and the large propane tank, installation of the heaters, and installation and connection of a buried propane supply line. The location and configuration of both the supplemental temporary heaters, and the permanent heaters, propane tank, and supply line are provided in Exhibit 49N. No. 7 North Escape Shaft (Section 20. TSN. R86W) A 1,066 foot escape borehole shaft was constructed into the No. 7 entry of North Mains to allow emergency evacuation of personnel from the development sections of the 9-Right and 10-Right gateroads. The construction of the shaft utilized raise drilling techniques. It is anticipated that the escape shaft will be utilized for approximately ten years. The site is shown on Figure 23, General Location of Escape Shaft. The drilling of the shaft resulted in minimal surface disturbance. A drill pad approximately 200 x 200 feet was constructed at the resulting site in 1,450 CY of cut and fill. Available topsoil was salvaged and stockpiled for future reclamation of the site immediately northeast of the drilled pad. Approximately 18 inches of topsoil derived from Cochetopa Loam is available for salvaging (222 CY). Casing and other drilling supplies were stockpiled on the borehole pad. After topsoil removal, two mud pits 10 x 10 x 7.5 feet were dug adjacent to the drillhole. Drilling fluids and cuttings were discharged into the adjacent pits, allowing settling in one pit, with water decanting into the adjacent pit. Drilling muds were used during the course of drilling the surface collar and pilot hole. The surface collar was approximately 5.0 feet in diameter, and the pilot hole was 11 inches in diameter. The collar was comprised of two components; a surface concrete pad and a liner or casing that extends to bedrock. A concrete centering base is at the bottom of the liner. av- MR09-234 2.05-45.7 02/03/09