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As part of the revised plan, the South Diversion Channel will remain in place and <br />continue to direct stormwater azound the reclaimed tailings surface. As a result, the <br />only surface water inputs to the Tailings Disposal Area will be direct precipitation, <br />runoff from the southern section of the reclaimed Mill Area, and runoff from the <br />hillslope azea to the north. This will result in a smaller spillway being needed to pass <br />the design flow (associated with the 100-yeaz, 24-hour storm) than was required <br />under the original reclamation plan, where the South Diversion Channel was to be <br />removed. The total acreage contributing surface water flows to the reclaimed <br />impoundment under the revised plan is approximately 191 acres. The peak flow <br />through the reclamation spillway during the 100-yr, 24-hr storm is estimated to be <br />approximately 134 cfs. <br />A preliminazy design was prepazed for the spillway to serve as the basis for the <br />revised reclamation cost estimate. Water will be conveyed from the tailings surface <br />to the existing stream channel downstream of the collection pond via a spillway <br />channel. The spillway channel will consist of three segments as described below: <br />~J <br />1. A 1500-foot-long upper segment connecting the low-point of the <br />reclaimed tailings surface (in the vicinity of the current 22.6-acre tailings <br />pool) with the drop structure (segment 2) immediately downstream of <br />tailings dam. This section of the channel will be constructed at a relatively <br />flat bed slope (0.3 to 0.5 %), with a bottom width of 3 feet, side slopes of <br />3:1 (h:v) and a depth of 3.5 feet. The peak velocity in this segment will <br />be approximately 3.75 fps during the design storm. Due to the relatively <br />low peak velocity during the design storm, erosion protection armoring <br />will not be needed in this segment. <br />2. A middle, drop-structure segment immediately downstream of the left <br />abutment of the tailings embankment. The drop-structure segment will be <br />approximately 540 feet long and constructed by excavating a channel in <br />native soil and weathered rock forming the hill slope. This section will <br />have a relatively steep bed slope (approximately 27%), with a finished <br />bottom width of 3 feet, side slopes of 2:1(h:v), and a depth of <br />approximately 1.5 feet. Due to the high velocities (up to 35 fps) <br />associated with the design storm, it is assumed that erosion protection, <br />consisting of a 6-inch thick concrete facing, will be required for this <br />segment. It is assumed that a 20-foot long by 6-foot wide stilling basin <br />will be required at the downstream end of this segment. <br />Battle Mountain Resources, /nc. E-3 Telesto Solutions, Inc. <br />v:wuixvl2t2-Newmoa(savL~u)\Savl.uisNermv nmeibmem- wra rv Managemem~nenoitnmendmeM v3.tloc July 20o6 <br />