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8. Hydrology and Sediment Control for Mining <br />No major streams or intermittent streams intersect the disturbed area although the Colorado River is <br />located approximately 600 feet to the south of the southern edge of the permit area. Sediment con- <br />trol for the permit area is provided by 3 items: 1) An earth berm will be placed on the existing ter- <br />rain along the perimeter of the site. All mnoff from the Gilsonite Pit disturbed area will be trapped <br />inside this berm and will primarily enter the pit excavation. The berm will be a minimum of 1.5 feet <br />high with 2H:1V sideslopes. It will be constructed from topsoil excavated from the area near the <br />sediment pond, 2) a small v-ditch of 1.5 feet depth around the staging area which will drain toward <br />the pit excavation and 3) a sediment pond of approximately 1.0 acres in size at the northern edge of <br />the permit area to temporarily detain the water from pit pumping prior to discharge. <br />It is not expected that [he site will discharge fora 100 year event in the upstream drainage area. The <br />site is located slightly within the 100 year floodplain of the Colorado River, as shown on Map C-1. <br />If water inundates part of the pit, all mobile equipment will be moved to higher ground and the pit <br />will be allowed to fill. The pit will serve to lower peak flows downstream and possibly lessen dam- <br />age by storing some water in the excavated area. It is not likely [hat the pit lake will be captured by <br />the river since it is over 600 feet away and the river does not have a main channel outside bend near <br />the permit area. Also, the floodplain at this area is very wide and shallow and does not contain <br />highly erosive velocities. <br />9. Water Information. Rights and Augmentation <br />All water rights issues such as availability of water for this operation, consumption rates, dust con- <br />trol, etc. is presented in Exhibit G -Water Information. <br />10. Schedule of Operations <br />Mining operations will only occur as dictated by demand up to the maximum rates described earlier <br />in the mine plan. Mining may occur in winter months. The operator does not anticipate night gravel <br />mining operations, although minor track activity or repairs may occur after dark. <br />Gilsonite Pit 10/02 14 <br />