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1 j&eMWWC WtW,LLC <br /> Additional information and detail is provided for the following issues: <br /> a. How the water will be routed to a north drift. The north drift intersects the main <br /> tunnel at the 80-foot level. The normal discharge is routed to the south portal at this <br /> point. Diversion to the north drift is accomplished by a simple earthen or sand bag <br /> diversion structure. The diversion structures will not exceed 1 foot in height. <br /> b. Volume calculations to demonstrate adequacy. Based on observations of the <br /> saturation of the blockage,a reservoir of water that may exist behind the blockage is <br /> estimated to be 3 to 4 feet deep. The blockage will be systematically removed <br /> (lowered)to control the rate of discharge. The north drift provides a buffer of 5,600 <br /> cf3 to address possible surges in discharge. <br /> As a contingency and an additional precaution;Maisie has the ability to restrict the <br /> rate of discharge by temporarily constructing small dams at the site of the first <br /> blockage and at the site of the diversion to the north drift. These temporary <br /> reservoirs add an additional 14,364 ft3 surge capacity: 7,350 ft3 from the first <br /> blockage reservoir and 7,014 ft3 from the site of the north drift diversion. The <br /> reservoir at the first blockage would be no more than 3 feet deep and the reservoir at <br /> the north drift diversion would be no more than 20 inches deep. Currently,water <br /> through the first blockage is routed through a channel that is approximatelyl.5-to 2- <br /> feet wide and construction of a temporary dam would not be a major undertaking. <br /> The north drift surge capacity and the contingency surge capacities total 19,964 ft3, <br /> which is greater than the estimated volume of the reservoir behind the blockage. <br /> However,the critical issues are(1)releases from the reservoir behind the blockage <br /> can be controlled and managed by the mining process,and(2)the discharge <br /> absorption rate(70+gpm)significantly exceeds the steady state required discharge <br /> rate. The absorption rate of 70+gpm is able to accommodate the entire estimated <br /> reservoir volume in less than 35 hours. <br /> Estimated volume of reservoir behind blockage: <br /> 19,600 ft3 or 146,608 gallons (7ft*4ft*1,400ft)/2 <br /> Assumptions: <br /> Main tunnel width: 7ft <br /> Reservoir depth: 4ft <br /> Main tunnel grade: 0.5% <br /> Reservoir length: 1,400 ft <br /> Gallons per cubic foot: 7.48 <br /> Estimate surge volume in north drift: <br /> 5,600 ft3 or 41,888 gallons(7ft*1 ft*800ft) <br /> Assumptions: <br /> Main tunnel width: 7ft <br /> Freeboard in drift: lft <br /> Drift length: 800 ft <br /> Gallons per cubic foot: 7.48 <br /> Estimated volume of temporary reservoir constructed(if needed)at the <br /> first blockage: 7,350 ft3 or 54,978 gallons (7ft*3ft*700ft)/2 <br />