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- 3 - 10. Please modify Map 4, Kerr Mine Plan, and Map 22 Surface Water Hydrology to show the exact locations of haul roads, access roads and light use roads. The Division needs this information to assess grade and distances per Rules 4.03.1(3)(a) and (b), 4.03.2(3)(a) and (b) and 4.03.3(a) and (b). In addition, the Division needs this information to evaluate drainage and culvert design per 4.03.1(4), 4.03.2(4) and 4.03.3(4). Drainage Structures - Rules 4.05.5, 4.05.6, 4.05.9, 4.06.4 and 4.14.1 11. The Division is reluctant to approve collection ditches for the 2-year 24-hour event when the edge of the disturbed area is so close to the permit boundaries. Failure due to inadequate capacity could result in increased total suspended solids (TSS) and salts in water outside of the permit area. The 10-year, 24-hour precipitation designs would be more appropriate per Rule 4.05.5(1)(a) and Rule 4.05.3(1). 12. Collection ditches need to be provided around the entire circumference of overburden piles #2 and #3 to prevent possible off-site degradation. Rule 4.14.1(2)(b) and 4.05.5(2)(c). 13. Rule 4.05.4(2)(b) requires that sizing for permanent drainage structures utilize the 100 year, 24-hour precipitation event design. Please modify the calculations for the following ditches: I-4, I-5A, PD7, PD2 and the diversion ditch through the 720 Pit. Please ensure that rip-rap sections are also sized accordingly. 14. Cutoff trenches are an accepted good engineering practice as a precaution to strengthen and better seal pond embankments as described in the SCS publication in "Ponds", October, 1978. This design feature should be retained in Marr Strip dam designs (Rule 4.05.5(1)). 15. There is some confusion as to the proper routes of drainage in ditches that drain permanent overburden Pile #2 into sedimentation Ponds I and J. The Division needs clarification of the ditch flows on Map 22, (Volume 4). 16. Projected mining and reclamation operations will modify drainage oatterns significantly. Pond I, in particular, has the potential of being undersized due to these changes. The response to the previous question should answer most of these concerns. Kerr Coal should re-evaluate pond capacity calculations to assure adequate storage capacity of sedimentation ponds. Rule 4.05.6(31. 17. This revised post-mining drainage system does not return the mine plan area to AOC requirements as per our Rules. This proposed drainage system has the potential for concentrating large quantities of run-off. This design appears to have the possibility of being unstable in the future. The operator should address this situation, in accordance with Rules 4.05.3(3), 4.06.4(2)(d) and 4.05.4(4)(a).