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• The total revised estimate of sediment volume delivered <br /> _ to Mine 1 and 2 sediment pond is as follows: <br /> Mine 1 & 2 Effluent (estimate only) 0 . 010 of/year <br /> Mine 1 0. 122 of/year <br /> Mine 2 0 . 004 of/year <br /> Pad 3 0. 0014 <br /> Pad 4 0 . 0024 <br /> Total 0 . 140 of/year <br /> Attached are addenda sheets A-r, A-5 , and A-6 for Mines <br /> 3 , 4 , and 5 for design sediment storage ponds . <br /> C. Dewatering and Shortcircuiting (717 . 17 (e) 4 & 5.) <br /> "The water storage for mine 1 and 2 is not being <br /> dewatered as required by this section. A principle <br /> spillway is needed, and should be eset at the top <br /> of the sediment storage volume elevation. To prevent <br /> shortcircuiting, to the extent possible, this princi- <br /> ple spillway should be set as far from the inflow <br /> point as possible. <br /> i • <br /> The design concept for the pond at Mine 1 and 2 is to <br /> include sediment storage for a full 3-year period as well <br /> as contain one 10-year design storm and mine effluent 0 . 4 <br /> cfs average inflow. (40 ppm suspended solids) <br /> The :tee" spillway (Rev. Plate 472.) is designed to function <br /> both as principle and emergency spillways . The elevation <br /> of the lower principle spillway opening corresponds with <br /> the maximum 3-year sediment pool level. The elevation <br /> of the upper emergency spillway opening corresponds to <br /> the 100 per cent storage level for a 10-year 24-hour <br /> design storm event. <br /> The mine effluent discharge is contained within the <br /> portion of the sediment pond allotted to 3-year sediment <br /> -3-• <br />