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Exh. 7-14PP-2 Revision Date: 1/30/23 <br /> Revision No.: TR-158 <br />captured a similar flow as produced by the upstream structure flowing into EP1 into the dummy <br />EP1 stock pond. This allows flows to be properly routed through multiple spillways reporting to <br />different structures in the model. Also, the dummy Ep1 stock pond receives an inflow nearly <br />similar to the inflow of EP1; therefore, artificially increasing the total amount of surface water <br />runoff into those structures in the model. <br /> <br />In summary, for the post mining condition, the 10-year, 24-hour storm produces 1.35 acre-feet of <br />runoff into Prospect Pond, and the peak settleable solids concentration is 0.00 mg/l. For the 25- <br />year, 24-hour storm event, the storm produces 11.9 acre-feet of runoff into Prospect Pond, and <br />the storm peaks at the 6,750.1’ elevation which is below the emergency spillway elevation of <br />6,752’. <br /> <br />Temporary Ditches <br /> <br />The Prospection Collection Ditch and the South Collection Ditch route water from native, <br />disturbed, and reclaimed areas to Prospect Pond. The location of both temporary ditches can be <br />found on Map 12 and Figure Exh. 7-14PP-2. Design information for the temporary ditches are <br />as follows: <br /> <br /> Prospect Collection Ditch <br />Station Peak Flow <br />(CFS) <br />Average <br />Slope <br />(%) <br />Channel Type Side <br />Slopes <br />Total <br />Depth <br />Erosion <br />Protection <br />0+00 to 16+50 0.57 3.0 V Ditch 2’ <br />Bottom Width <br />1H:1V Left <br />7H:1V <br />Right <br />0.5 Vegetation <br /> <br /> <br /> <br />South Collection Ditch <br />Station Peak Flow <br />(CFS) <br />Average <br />Slope <br />(%) <br />Channel Type Side <br />Slopes <br />Total <br />Depth <br />Erosion <br />Protection <br />0+00 to 30+00 6.23 5.0 V Ditch 2’ <br />Bottom Width <br />1H:1V Left <br />7H:1V <br />Right <br />1.2 Vegetation <br />30+00 to <br />90+00 1.32 4.0 V Ditch 2’ <br />Bottom Width <br />1H:1V Left <br />7H:1V <br />Right <br />0.5 Vegetation <br />90+00 to <br />92+68 0.64 3.0 V Ditch 2’ <br />Bottom Width <br />1H:1V Left <br />7H:1V <br />Right <br />0.5 Vegetation <br /> <br />Permanent Post Mine Channels <br /> <br />The Prospect Pond watershed is comprised of five post-mining channels. The locations of these <br />channels are presented on Map 12 and Figure Exh. 7-14PP-2, and the channel profiles are <br />presented on Map 33.