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S%HIBIT G <br />WATE1~ INFORMATION <br />In the Platte Valley Pit, material will be mined by a dry method. <br />When the mining first encounters the groundwater, a pump will be <br />instaalled to remove the water from the pit. This water will be <br />discharged into the concrete lined ditch of the Central Colorado <br />Conservancy District which will carry it into the South Platte <br />River. The water will discharge into the river at the Weld <br />Count:y Road 6 bridge. In a dewatered state, the material can be <br />excavated by a front loader and put directly onto a conveyor belt <br />for transport to the processing plant. <br />Surface Drainage <br />The surrounding area is predominately agricultural in nature. <br />There: are several minor industrial properties located along the <br />eastern boundary of the property. Off-site drainage to the <br />property is partially controlled by the location of U.S. 85. <br />Runo1'.f from the property flows directly to the South Platte <br />River. <br />The gradient of the river is 10 to 15 feet per mile and the <br />channel width ranges from 50 to 200 feet. The meander length of <br />the river varies from 1,500 to 2,000 feet. Where the mining <br />approaches the river on the south end, the river has a straight <br />cour:oe and is not cutting either side. <br />The toajority of the Platte Valley Pit lies within the 100 year <br />floodplain. The proposed location of the plant site and <br />stocl~:piles would lie outside the floodplain. The mining plan <br />would not impact the floodplain. Erosion that may occur during a <br />major flood would be contained within the pit. <br />In order to direct flood flows during a major event and to <br />minimize any flood erosion damage, the following measures are <br />proposed. <br />1. There is an existing 4 foot high dike built along the west <br />property line. We assume this dike was built during the <br />1960s by the U.S. Army Corps of Engineers. On the south <br />side of Cell A, the mining approaches the river at Its <br />closest point. Here we propose to armor approximately 400 <br />feet of the existing dike. The armoring will be of waste <br />concrete placed on the river side of the dike. In addition, <br />the dike will be heightened by approximately 2 feet. This <br />riprap will then be covered with soil and seeded in grass. <br />G-1 <br />