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Mining Plan <br />• Areas MV and MS are completed, major excavation would begin in Area H and that would <br />continue until the end of the operation. <br />WATER DIVERSION AND IMPOUNDMENTS <br />All water control measures at this operation are under the control of the stormwater <br />management plan. That plan, part of which is already in place and was created nearly ]0 years <br />ago, and part of which must still be constructed, will be periodically reviewed and modified as <br />the operation proceeds. <br />The emphasis of the stormwater management plan is in two parts. First, is the prevention <br />of heavy sediment and stormwater flows from the site. This is accomplished by maintaining, <br />as much as possible, "informal" detention areas within the mine. These are "informal" in that <br />they are composed of mine pits and other depressions that simply capture stormwater and <br />sediment and prevent it from entering the lower portions of the permit where the more "formal" <br />controls are currently th place or will be in place soon. <br />The "formal" stormwater controls include the use of culverts to dvect the water and <br />sediment to a series of sediment basins that capture the sediment and allow much cleaner water <br />to pass though. Open drainage paths will be protected primarily with drop structures that act <br />as energy dissipators, minor sediment collection areas, and streambank protectors. <br />A final sediment basin near the east edge of the permit that will be constructed before <br />May 27, 1994, provides a final treatment area. This basin was included in the stormwater <br />management facilities technical revision submitted in January 1994. This allows for capture of <br />any sediment that manages to get past the upper sediment basins and drop structures. <br />A key element of the stormwater management plan is maintaining a high available <br />sediment capacity in the sediment basins. This is accomplished by periodically cleaning out the <br />sediment basins when the sediment reaches a certain level. By maintaining the upper sediment <br />basins the final treatment basin should not receive much sediment. [f much sediment <br />accumulates in the final treatment basin then either the upper sediment basins need to be cleaned <br />or the storm event that deposited the sediment in the final treatment basin exceeded the capacity <br />of the system. In either event, large amounts of sediment in the final treatment basin indicate <br />a need to clean the upper sediment basins. <br />• <br />Pikeview puarry Amendment Exhibit D Page 25 <br />