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• will have a berm surrounding it to detain fines. The sump will allow for all sediments to settle out of <br />the discharged water. The sediment sump will be approximately 90 feet wide and 160 feet long. From <br />the sump, the water will overflow into the White River and the nearby wetlands. An NPDES permit is <br />in place for the operation currently, and it will be updated with new discharge points. Selenium <br />concentration in the discharge water will not be monitored as it is not required for the NPDES permit. <br />Selenium has not been a problem in this part of Colorado. Pumping will take place at a rate of 500 <br />gallons per minute. <br />All of the pit water will be pumped into the White River or wetlands during mining. Wetlands within <br />the disturbance area as seen on Map C-3 will be excavated under the USACOE Tulloch Rule. <br />Therefore, no fill of any kind will be placed within the wetland footprint area at any t. This <br />includes backfill, topsoil, and/or stockpiles. A Gravel Well Permit will be applied for with the <br />Colorado Division of Water Resources. No augmentation plan is needed since this area has under <br />appropriated water available. <br />• The mining of the deposit will occur to the limits shown on Map C-3 with slopes no steeper than <br />2H:1 V around the perimeter of the pit. The interior slopes however, maybe mined using a 0.5H:1 V to <br />near vertical slope on active mining faces. Highwall mining will progress to the final 3H:1 V & 6H:1 V <br />slopes. The 6H:1 V slopes will be mined to along the north and west sides of the pit down to 10 feet <br />below the water level. The remainder of the perimeter will be 311:1 V to 10 feet below the water level. <br />Below this the slopes may be up to 211:1 V. The 6H:1 V slopes will reduce erosion if the water over tops <br />the buffer, and will facilitate the return of vegetation without topsoil in reclamation. This slope will <br />revegetate as a wetland. Overburden occurs in sufficient quantities on the site to create the wetland <br />shelf as designed. The slopes are expected to be stable, as it is used at similar sites in the area with no <br />slope failures. Any failure would be governed by the internal angle of friction of the material. This <br />would limit the failed slope to an angle of 38 degrees or -1.3H:1 V. No slope within the plan reaches <br />any angle close to 38 degrees. <br />The anticipated future average total tonnage sold from the site in any one calendar year is 500,000 <br />tons. Table D-1 below shows a breakdown of the expected average annual production. <br />• <br />White River City Pit, August 08 D-3