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32.05 APPLICATION FOR PERMIT FOR SIIRFACE OR UNDERGROUND MINING ACTIVITIES -- MINIMOM REQUIREMENTS FOR OPERATION AND RECLAMATION PLANS. 2.05.6 Mitigation of Surface Coal Mining Operation Impacts. (Cont'd.) (3) (b) (i) (Cont'd.) empty into the sedimentation pond. This pond has been designed to store the 10-year, 24- hour storm event with no discharge and also has been designed to store appropriate levels of sediment. The design is based on runoff levels of 0.04 inches per acre for undisturbed areas and 0.83 inches per acre for disturbed areas. The pond has been designed to store 0.1 acre feet per acre of sediment. The pond will be cleaned and maintained as is described in the existing approved permit. Appropriate level markers will be constructed to aid in this maintenance. A1I dewatering devices, free board, and spillways have been designed and will be constructed following applicable regulations. See Appendix E. Small area exemptions have been approved for the outslopes of the portal level fill embank- ~~ ment. Refer to the Orchard Valley West Mine Small Area Exemption Application in the Ponds, Impoundments and Dams Appendix, Voliane SA. Minimal groundwater inflows are expected in the Orchard Valley West Mine. The permeabili- ty of the coal seam implies that little dewa- tering and subsequent groundwater inflow will be anticipated. This small anticipated groundwater inflow is similar to that experi- enced at the Orchard Valley Mine. If mine in- flow was significant and discharge from the mine was warranted, all flows would be routed through the sedimentation pond. Discharge from the sedimentation pond would meet all NPDF.S discharge requirements. The proposed haul road drainage control plan is similar to that stated for the existing haul road. Appropriate ditches and culverts have been designed and will be constructed to minimize erosion and sedimentation along this road. The road route follows an existing Added 10/12/86 Revised 10/01/87 1Q8