2004-05-19_REVISION - M1979205 (2)

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Water Information Exhibit G The pits from this operation ]ie on both sides of the Colorado River. A]l pits will be flooded once mining and reclamation has been completed. Controls for both surface and ground water are included in this plan. Surface water exists in two forms in this pit. The river runs between the current mining area and the Scott Expansion. A minimum buffer of 100 feet will be maintained between the river and all new pits. This buffer will provide a sufficient safety factor against river capture. The second form of surface water will be storm and process water discharge. Substantial water will be discharged throughout the mines life. Pumping will occur continuously in the original pit for the life of the mine. This is due to the pit bottom being used as the staging area. Water will be pumped from dewatering trenches into the pre-law pond between the pit and the river. Sediment will be allowed to settle in this pond prior to discharge. A dischazge permit has been granted for this discharge point. Pumping will also occur in at least one of the mining areas of the Scott Expansion. At times two azeas may be pumped to provide access to both. Pits will be pumped by allowing water to drain through dewatering trenches located azound all or portions of the pit perimeter. Gravel filters may be used in these trenches to reduce sediment prior to pumping. Water will be pumped into a settling pond prior to dischazge. In some cases this will be a 200'x 20'x 4' constructed pond, however once mining azeas have been reclaimed, the lakes themselves will be used as settling ponds. Smaller settling ponds will be used to maintain sufficient water in the existing wetlands. These ponds will be substantially smaller. This is due to the reduced flow of the smaller irrigation pumps. All settling ponds can be seen on Map C-2 and C-3. These ponds will be reclaimed as wetlands or filled in. All planned discharge points will be included in the storm and process water discharge The following scenario is expected dewatering plan for the Scott Expansion. This plan may change due to unexpected hydrological conditions. However, the concept of all discharge water entering a settling pond will be maintained. Prior to mining in Area 1, a major settling pond (200' x 40' x 4') will be constructed between the mining area and the river. The discharge point of the settling pond will be armored with rip- rap to prevent erosion. Dewatering trenches will then be dug in order to lower the pits water table. Water will then be pumped from the ditches to the settling pond prior to discharge. Trenches will progress both outward and down during the mining area's life to the ultimate limits shown on Map C-2 and C3. In order to maintain the surrounding wetlands, a smaller irrigation pump will be used to discharge water into the wetlands. Irrigation of the wetlands will begin as soon as pit dewatering begins affecting the hydrology of the wetland. The irrigation pump will pump to a minor settling pond(100' x 10'x 4') prior to discharging into the wetland. Once mining has been completed or slightly before mining has been completed, 4/26/OA Page G-7