1993-03-22_REVISION - M1977378 - Laserfiche WebLink

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Sunnyside Gold Corp. Page 8 March 10, 1993 the elevation of the mine pool reaches the Lake Emma outflow elevation. In this case a dynamic seasonal mine pool elevation will result. In either case, water entering the natural surface fracture system during spring runoff should be stored primarily within the natural fracture system. Annual mine pool water level fluctuations will give a rough indication of the natural fracture connection between the mine and the surface water drainage system. Water entering the mine will raise the elevation of the mine pool increasing the hydraulic head resistance to more water entering. Later, during the dry season, water stored in the fracture system and in the case of a fluctuating mine pool elevation a portion of the mine pool, will reenter the surface drainage system. Any stream flow contamination occurring after closure of the bulkheads and equilibrium impoundment of water within the Sunnyside Mine should primarily be from near-surface natural in-fracture oxidation of metallic sulfides, the same process that was taking place prior to mining. DESIGN CRITERIA The four bulkhead locations were selected to maximize the distance that water impounded in the mine would have to flow along the high-resistance natural fracture system to reach the ground surface. These locations were also selected to avoid major faults which could potentially provide a natural path for impounded water to exit the mine. The American Tunnel bulkhead is approximately 7950 feet from the portal at an elevation of 10660 feet. The depth of the American Tunnel bulkhead is approximately 2130 feet below the overlying ground surface. The Lake Emma outflow, 1550 feet above the bulkhead, is designed to be the outflow path for any groundwater entering the Sunnyside Mine between the F-Level bulkheads, elevation approximately 11570 feet, and the American Tunnel bulkhead. The Terry Tunnel bulkhead on F-Level is approximately 650 feet below the Lake Emma outflow and approximately 1160 feet below the overlying ground surface. The Terry Tunnel bulkhead is located over 3800 feet from the Terry Tunnel portal. The Terry Tunnel bulkhead is designed to eliminate discharge of mine water from the Terry Tunnel portal. The Brenneman-Sunnyside F-Level bulkhead is 630 feet below the Lake Emma outflow and approximately 1200 feet below the overlying ground surface. The Brenneman-Sunnyside F-Level bulkhead is designed to prevent impounded Sunnyside Mine water from flowing into the Brenneman-Mogul Mine and exiting to the surface through Brenneman-Mogul Mine workings. The F-Level Terry Tunnel and Brenneman-Sunnyside bulkheads are also designed to provide hydraulic back pressure to resist near-surface fracture groundwater from entering the Sunnyside Mine between the F-Level, elevation approximately 11570 feet, and the Brenneman-Sunnyside B-Level bulkhead, elevation approximately 12140 feet.