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• EXHIBIT 7, ITEM 14, PART O <br />SECTION 16 POND DITCH EXTENSIOI\f <br />The location of the Section 16 Pond is presented on Map 41. This analysis has been done as the <br />Section 16 Side collector ditch is lengthened for mining activities associated with the Section 16 <br />Pit extension under TR-65. The profiles of the associated ditches are presented on Map 33A. <br />Channel design of these drainage channels is provided in Exhibit 7, :[tem 14. Exhibit 7, Item <br />140, Figure 1 shows the breakdown of drainage areas and hydrologic conditions for this ditch <br />and sediment pond, and Figure 2 provides a diagram of the structures and networking. Longer <br />term, the Section 16 Pit extension area will be remined under the South Taylor mine plan, and <br />associated hydrologic design for those facilities are presented in Exhibit 7, Item 20. <br />To minimize the size of the resultant runoff, two sediment control traps along the disturbance <br />boundary will be utilized. It is expected that these sediment traps will he relocated as the topsoil <br />replacement progresses. Thus the life of these structures will generally be less than one year. <br />These sediment traps will be subgrade (excavated by dozing) and will leave a maximum capacity <br />of 1.0 acre-feet. The sediment traps will typically be rectangular in shape with a maximum depth <br />of 10 feet and a maximum of 2H:1 V side slopes. They will be evacuated by pumping when <br />needed. <br />The following pages present the results of single SEDCAD run under ithe worst case hydrologic <br />conditions during mining for the 10 year, 24 hour design storm. Thia design event generated <br />• about 30 cfs of peak runoff and a total runoff volume of about 3.3 acre-feet under these <br />conditions. Volume 2E contains several other SEDCAD runs for the Section 16 Pond for the <br />postmining case, including a case using the 100 year event for spillway adequacy. <br />• <br />Exh. 7-140-1 Revision Date: 5/25/07 <br />Revision No.: TR-65 <br />