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plan of 2008. The USACOE has approved the plan for this pit as shown by the letter from the <br />USACOE in July of 2008. This letter is enclosed in Appendix C. <br />2. Site Geology <br />The site contains Pleistocene age gravels with bedrock of Wasatch Formation shale and sandstone. <br />The oxbow was once an active channel of the river, but due to deposition in the oxbow and <br />degradation of the main stem, the oxbow has been naturally cut off from the current river channel. <br />The gravel depth is expected to be 25 feet. The gravel has very little fines and is very permeable. <br />In the irrigated fields, up to 5 feet of overburden is expected. The rest of the property has little <br />overburden. The topsoil in this area is also thicker than in the riparian areas. The topsoil is <br />expected to be 3 inches to over 1 foot in thickness as an average over the disturbed area. Average <br />topsoil and overburden depths can be seen in the Mining Area Volumes table. The water table <br />level is expected to be around 5300'-531 P in elevation. <br />3. Pre-Mining Work <br />Pre-mining activities for the Scott Expansion will consist of infrastructure installation, topsoil and <br />overburden stripping, and site sloping to ensure all disturbed areas will drain into the pit. These <br />activities will take place in and around Mining Area 1 prior to mining. Mining Area 2 will be <br />prepared in a similar fashion when Mining Area 1 is mined out. <br />The pre-mining facilities to be installed are the office trailer, scale, and porto-potties. See Map C- <br />2 <br />4. Stormwater Control <br />The disturbed areas of the site will be sloped to isolate the site from the surrounding area. <br />Therefore, all run-off will drain to the pits during the mining operation. The active pit will have a <br />pit pump as shown on Map C-2 that pumps clean water to the river. A combined <br />stormwater/process water discharge permit will be obtained for the discharge from the pit pumps. <br />The stormwater volume was determined using the calculations below as described in the <br />"Procedures for Determining Peak Flows in Colorado", which includes and supplements Technical <br />Scott Pit March 10 D-2