Laserfiche WebLink
Sunnyside Gold Corp. Page 7 March 10, 1993 <br /> The poorly defined, but low, bond strength between the rock and the <br /> concrete was conservatively ignored in the calculations. <br /> The optimum solution to drainage of water containing metallic <br /> and sulfate ions from the Sunnyside Mine, or any other mine, is to <br /> fill the entire mine with an impermeable backfill. Complete <br /> backfilling, if possible, would come the closest to restoring <br /> original groundwater conditions. Backfilling would eliminate the <br /> low resistance groundwater flow paths presented by the mine <br /> workings. Such a solution can neither be accomplished safely nor <br /> practically because many of the mine openings are no longer <br /> accessible. The volume of even the accessible mine openings <br /> renders even incomplete backfilling uneconomic. <br /> Impoundment of water in the Sunnyside Mine behind bulkheads <br /> can be equally effective as backfilling in preventing contaminated <br /> mine drainage from re-entering the surface water system. The <br /> bulkheads were carefully located and designed to eliminate leakage <br /> around the bulkheads, to prevent the development of uncontrolled <br /> releases of contaminated mine water to the ground surface along <br /> natural flow paths and to assure that the bulkheads will remain <br /> stable and effective. The essentially stagnant mine pool that will <br /> be developed at the Sunnyside Mine is designed to maintain the mine <br /> pool below the elevation that will potentially force contaminated <br /> water through any known natural fracture system to reenter the <br /> surface water system. <br /> This report presents the purpose of the bulkhead system, the <br /> design criteria and the individual bulkhead designs. <br /> PURPOSE <br /> A single bulkhead can be used to close a single low resistance <br /> groundwater flow path, the tunnel, and eliminate that mine <br /> controlled discharge point. The Sunnyside Mine is unique in that <br /> four bulkheads have the potential to raise the mine depressed <br /> groundwater level 1550 feet, to the 12210-foot elevation of the <br /> Lake Emma drainage ditch outflow. These four bulkheads are 1 <br /> designed to isolate the Sunnyside Mine from all potential drainage <br /> paths to the ground surface below the Lake Emma outflow and <br /> reestablish the pre-mining groundwater conditions below the Lake <br /> Emma outflow. The Sunnyside Mine bulkhead based mine drainage <br /> control system is designed to prevent groundwater that enters the <br /> natural near-surface fracture system below Lake Emma from migrating <br /> into the mine workings. The pressure of the impounded water should <br /> resist movement of groundwater into the Sunnyside Mine. <br /> If, or when, the water level in the Sunnyside Mine reaches its <br /> maximum 12210-foot elevation, stable ground water equilibrium with <br /> respect to the mine should be established. After that time, major <br /> groundwater movement, below the Lake Emma outflow should be the <br /> same as the pre-mining surface fracture controlled groundwater <br /> system. On the other hand, leakage of water impounded in the mine <br /> to the natural fracture system may balance the inflow rate before <br />