2012-07-11_PERMIT FILE - C1984065 (2)

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the working stope is desirable. The sequence of mining must be . carefully balanced, and while studies of the rock mechanics involved will be of some use, the optimum cycle will be established with field experience. Initial mine development requires sufficient air to ventilate two splits and maintain air quality in three additional splits. Mini- mum requirements are 30,000 cubic feet per minute (cfm) at 2-inch water gauge. A two stage blowing fan with the second stage to be added after initial development is planned. Installed capacity will be a reversible 100,000 cfm unit with 5-inch water gauge capability. when the mine is operating at 2,200,000 tpy, after the fifth year, it is estimated t}~at nearly 200,000 cfm of air will be required. This will probably involve two separate ventilation circuits. Ventilation shafts and the location of fans are shown on Figures 9.3-3 and Figure 9.3-9, respectively. The purpose of the openings referred to is to provide mine exhaust • and escapeways (in the case of emergency). Present mine design considers driving these entries from the underground workings by cross cutting to the surface where the portal(s) and access pad(s) will be located. NCIG intends to design the above-mentioned mine openings to support the ground and maintain slope stability in the area of the portal. A preliminary geotechnical investigation has been conducted to determine the type and properties of soils to be encountered on the northeast slope of the Grand Hogback. The results were incorporat- ed into the engineering design of the facilities and actual placement, based on slope and entry stability. The soils and weathered materials have a total thickness of 30 feet. These materials mostly consist of sandy clay or gravel with the typical physical properties having the density of around 105 . NCIG - Coal Ridge #1 4-17 ABC/1145/910509 ~-7