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_~ <br />~.~ <br />Dozers may also be used to move topsoil or gravel. There will be no blasting as part of this <br />operation. <br />Mining and screening/washing activities aze expected to occur at intervals during the year. <br />Mining will proceed in general from east to west through Phases 1 through 3 numerically. At any <br />one time, there may be portions of two mining phases active. The overburden from Phase 1 will <br />be permanently stored in the staging area, as shown on Map C-2.Once Phase 1 is mined out, the <br />crusher and screen plant will be placed in the bottom of Phase 1. From there, it will move to the <br />subsequent 2 phases. Overburden and excess topsoil from Phases 2 and 3 will be used to backfill <br />selected locations along the pit sides to create a sinuous and pleasing lake edge once the azea is <br />reclaimed. See Map F for details of the final lake configuration. <br />Prior to mining below the water table, a sediment sump will be created in the northeast comer of <br />the disturbed area. This sump will handle the 10 yeaz event runoff from Phase 1. The sediment <br />sump will only need to contain an event before mining begins. Once mining commences, the pit <br />itself will serve as the sediment detention structure. Due to wet conditions, the pit will need to <br />be pumped. This water will be collected in a depression in the pit which will pump the water to <br />the sump described above. See Map C-2 for details. The in pit depression will have a berm <br />surrounding it to detain fines. The sump will allow for all sediments to settle out of the <br />dischazged water. The sediment sump will be approximately 30 feet wide and 100 feet long. <br />From the sump, the water will overflow into the new irrigation ditch which drains to the White <br />River. The maximum carrying capacity of this ditch faz exceeds the needs of the water which <br />will be discharged. An NPDES permit will be needed for the discharge. The permit application <br />has been submitted. Selenium concentration in the dischazge water will not be monitored as it is <br />not required for the NPDES permit. Water will initially be pumped at the rate of approximately <br />4000 gallons per minute for a period of 30 days. Pumping will then be reduced for the next 11 <br />months to a rate of 500 gallons per minute. <br />This rate is 529 acre-feet for the first month and 66 acre feet for each of the remaining 11 months <br />of the year. The total amount pumped annually in the first yeaz is therefore 1255 acre-feet. In <br />White River City Pit, Apri107 D-2 <br />