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• Downdrain #2, Downdrain #4 and the Final Pit Downdrain will be 9 inches instead of the 6 inches indicated in the design specifications. In some of the drainage channels, increasing the level of channel sinuosity was considered to be advantageous to increase the channel length thereby reducing overall channel gradient. When sinuosity was considered desirable, the minimum meander frequency was set at 290 feet per cycle and the maximum meander amplitude was set at 80 feet per cycle. A simplified diagram of these criteria are provided below: one Maximum 290' Minimum In conjunction with the Moffat drainage plan four culverts were proposed to be retained to enable runoff to pass under the proposed road system in the 'vicinity. These culverts include: MAC #3, MAC #8, ES and E6. Culvert ES • will be retained to pass runoff under the approved North Access Road while culverts MAC #3, MAC #8 and E6 are to be retained to pass runoff under the proposed Lower Moffat Road. The location of the culverts is provided on Exhibit 3.9-6. Design specifications for the MAC series culverts are provided in Appendix 3.5-D. Design specifications for culverts E5, and E6 are provided in Table 3.5-3. 3.4.2.2 West Ridge Grading Plan West Ridge was mined initially in the 1950's for the Lennox Seam and was not graded at that time. Remining and grading of the area was performed under the permanent regulatory program. Postmining contours for West Ridge are shown in Exhibit 3.9-1, Sheet 2. The final pit was located on the southern ridge cropline and grading eliminated any highwall remaining after mining. All grading on the West Ridge Mining area has been completed. Access roads presently exist on the graded spoils. When abandoned, these roads will be reshaped and seeded in accordance with Section 9.3. • Renewal-3 3.9-4 June 13, 1997