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the expected maximum rate of flow of water used to transport tailings <br /> to the pond will be approximately 900 gallons per minute. This is equivalent <br /> to 2 cfs, or 1 cfs/decant. Based on these calculated flow rates, each <br /> decant must pass a total of 1 .86 cfs to evacuate both storm runoff and <br /> normal mill water yields simultaneously. <br /> Because of differences in elevation head, the discharge from each <br /> decant will be less during the initial stages of operation of pond No. <br /> 4 than at later stages of operation, for the same volume of water evacuated. <br /> If the decants satisfy the drawdown criteria at a minimum elevation head, <br /> then it follows that the discharge will exceed the drawdown criteria <br /> proportionately as the elevation head increases with increased pond surface <br /> elevation. The flow velocity for each decant, as calculated from the <br /> Bernellis equation, for a minimum elevation head of 4 feet and a decant <br /> length of 600 feet, is 4.4 fps, and the discharge is 2.4 cfs, at a water <br /> temperature of 600F. Based on the above results, it is concluded that <br /> each decant will discharge 0.54 cfs in excess of the 1 .86 cfs required <br /> to pass, within 10 days, 90% of impounded rainfall runoff, assuming no <br /> infiltration or evaporation losses. <br /> The freeboard berm around the perimeter of the tailings pond No. 4 <br /> should be maintained at a minimum height of 3 feet and minimum width of <br /> 12 feet. This freeboard requirement is based on the possibility of a <br /> probable maximum thunderstorm occurring which could result in the <br /> i <br /> impoundment of 38 acre-feet of storm water. All winter berm heights <br /> ,i <br /> should include the minimum freeboard height. All freeboard berms should <br /> i <br /> be compacted in accordance with Appendix A, Section 3. 1 .4. <br /> a <br /> 24 <br /> 's <br />