2009-03-04_REVISION - C1982056 (2)

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from the 6-Main North substation and will be insulated and heated. The Polo Citrus tanks will be enclosed by a containment system capable of holding in excess of 5,000 gallons. The bulk material component includes construction of a pad, installation of a bulk material hopper, and drilling of a nominal 13-inch borehole from the surface to the underground workings from the shaft pad above the 6-North Main entries. Drilling of the borehole was covered by the TR05-48 submittal. Details for the concrete pad and bulk storage and transfer facilities will be submitted for review and approval as a Minor Revision, prior to installation. The water component includes construction of a reinforced concrete pad and footers, installation of a water tank and associated pumping installation, and drilling of a nominal 13-inch borehole from the surface to the underground workings from the shaft pad above the 6-North Main entries. Drilling of the borehole was covered by the TR05-48 submittal. TCC proposes to construct a steel water tank 85 feet in diameter and 24 feet high designed to hold one million gallons. The tank will rest on a reinforced concrete foundation consisting of a spread-footer, stem wall, and slab floor supported by concrete pilings. Preparation of the tank foundation area will involve grading, compaction, and excavation for the support pilings and spread- footer. Following site preparation, the reinforced concrete pilings and footers will be formed, and poured, followed by the reinforced concrete pad and stem wall. The steel tank will be fabricated in sections which will be placed and anchored on the stem wall. A water-tight liner system will complete the tank installation. A buried 8-inch HDPE line will connect the tank to the water borehole for both filling from and discharge to the mine water system. Pumps (both underground and at the surface) and control sensors and valving will allow for controlled flow in either direction in the supply system. Tank fill sensors and a monitored overflow drain will be installed in the tank to prevent overfilling. The overflow drain line will be installed in the same trench as the water supply and return line and will drain back to the mine-water handling system. A small 8 x 8 foot pumphouse, will be constructed next to the tank on a concrete foundation to house pumps and valves. Power and/or control communications will be laid in conduit above the waterline connecting the tank and the borehole. The locations for the seven boreholes for project utility components are shown on Maps EX16E-M1 and M2. As shown on Map 23, additional entries will be driven to the south of the 6 North Main entries to connect with the ventilation shaft. These entries will be needed to maximize the efficiency of the ventilation system. The entries will be driven in the same manner as is used in TCC's development work, Temporary Shaft Heater Installation (MR08-227) It is necessary to install temporary shaft heaters to address severe icing conditions within the shaft that have the potential to interfere with operation of the 6MN Emergency Escape Hoist. TCC proposes to move two portable skid-mounted propane air heaters (15' long, 7' wide, and 7.5' high) onto the existing 6MN Shaft Pad (would be located adjacent to and immediately west of the Escape Shaft Hoist-House (see MR07-218) approximately 50' from the shaft opening), and connect them to a portable propane tank, the existing electrical lines, and to the shaft opening with pre-fabricated vent tubing. In order to address the immediate icing problems, the volume of ventilation air moving down the shaft will be temporarily reduced by adjusting ventilation doors at the shaft bottom, and the remaining air-flow warmed with the portable heaters to thaw the water-ring and associated piping within the shaft collar and liner. TCC will inspect, and may make modifications to the water-ring and piping to reduce future potential for freezing and icing. The temporary heaters will remain in-place until the immediate icing problems are addressed (projected at up to 45 days), then full air flow will be restored to determine if there will be a continuing problem. If problems persist, the temporary heaters could remain in-place for the remainder of the winter (up to 4 months), with the potential that a permanent heater installation would be required (to be permitted separately, if necessary). MR08-227 2.05 - 45.6f APPROVEI) JAN : ? 2009 01/08/08