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L~ I~ The design sizes for the sediment pond spillways are set forth in Table 13-ti. Cross-sections showing the dewatering devices for each sediment pond are depicted in Exhibits 8B, 20, 21, 22, 53 and 55. Sediment ponds Nos. 6, 9, 10 and 13 will have a principal spillway consisting of a pipe installed just above the maximum sediment depth. Pond No. 6 was originally designed with a combination principal and emergency spillway. Redesign information providing for separate spillways on this pond is given in Appendix 13-2. The principal spillways will have normally closed manually operated gates or valves to control dewatering of the ponds. Sediment pond Nos. 1, 2, 7, 8, and 11 will require pumps for dewatering, since surrounding ground elevations are higher than the sediment pond bottom elevations. A portable pump will be rented for this application. The pumps will be operated manually when required. Manual dewatering valves can function as slow passive dewatering devices and also insure adequate detention time, so that effluent limitations will not be exceeded. After settling, the water level will not be allowed to stay above the maximum design sediment level as marked by sediment stakes or measurements from the spillway. Rule 4.05.9(2)(e) allows the DMG to approve a temporary impoundment that relies primarily on storage to control run-off from the design event specified in 4.05.9(2)(c) which is the 25 year 24 hour precipitation event. As shown on Exhibit 55, pond 11 has adequate capacity to contain the 25 year 24 hour precipitation event with substantial freeboard. Therefore, an emergency spillway is not required at pond 11. Primarily due to the lack of capacity in sumps in the Roadside North portals, Pond 12 was designed in 1997 to act as a surface water treatment pond for mine water discharge. The primary spillway was controlled by a manually operated valve which allows regulation of the water level and detention time. Design information is included in Appendix 13-2. Pond 12 was partially reclaimed during the fourth quarter of 2001 and completely reclaimed concurrently with the reclamation of the North Portal. Pond No. 13 was constructed concurrently with the reclamation of the North Portal. The design for this pond is presented in Appendix 14-6 beginning on page 14-6-53. This new pond is shown on Exhibit 86. 13-7 (Rev 10/05)