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WATER INFORMATION EXHIBIT G <br />1. Surface Water General Discussion <br />The entire permit area is within the 100 year floodplain of the Yampa River. If a 100 year flood <br />occurs in the River, the 1982 datum shows that the water level at this site will be 6188' at the <br />western end of the permit area and 6195' at the upstream east end. Since there are no structures <br />within the mine pit area, the flood would simply be allowed to enter the pit. Once the flood <br />subsides and the water can be pumped cleanly, dewatering of the pit would resume. Any storage <br />provided by the pit would actually serve to lower the peak flow downstream and possibly <br />prevent damage to properties. If water nears the level which would enter the pit, all mobile <br />equipment would be removed from the pit and placed outside the 100 year floodplain. <br />Portable sanitation facilities are already in place at Bunn Ranch, but more facilities will be setup <br />on the Gehrman site. There will be no leach fields or other means of sewage disposal. <br />2. Hydrology and Sediment Control for Mining <br />No major streams or intermittent streams intersect the disturbed areas, although the Yampa River <br />comes right up to the southern edge of the permit area at its closest point. Sediment control for <br />the permit area is provided by the following: <br />1) A sediment pond of approximately 2.0 acre-ft. in size at the northwest edge of the permit area <br />to temporarily detain the water from the pit pumping prior to discharge. <br />2) Pumping in the pit will utilize gravel berms around the inlet to provide filtering of sediment <br />before the water is pumped. <br />Since the mine will encounter water in the mining operation below 4'excavation, pit pumping is <br />needed. A diesel powered pump will be placed at the low point of Phase 1, from which PVC pipe <br />will deliver the water to the sediment pond. See Map C-2. Pumping is expected to be from 1000 <br />Gehrman Pit October 09 G-1