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<br />• downgradient drainage structures have been reviewed and revised as <br />appropriate to handle the resulting additional flows. Revised drainage <br />design calculations are presented in Appendix A, Drainage Design <br />Information. <br />1 [~ The southern and central portions of the north collection ditch of Pit <br />i 6. <br />Response (1 B): The referenced "north collection ditch" is an upland <br />clean-water diversion which will be removed and reclaimed as noted <br />above. <br />(1 C) The collection ditch on the south and west sides of Pit 4. <br />\ Response {1C): The collection ditch on the south and west sides of <br />~br Pit 4 still exists, however, it is not essential to effective drainage in this <br />~\ <br />area and appears to have been constructed as an internal drainage <br />component to keep disturbed area drainage out of the small <br />undisturbed area south of the previous Pit 4 shop area. Rockcastle <br />proposes to remove this ditch and reclaim the associated disturbance <br />area. Overall drainage and sediment control will not be affected since <br />this area will still drain to the south collection ditch, which routes flows <br />~ to Pond 4. - <br /> <br />(1D) The collection ditch on the north side of the disturbed areas of Pit 4. <br />' Response (iD): The ditch on the north side of Pit 4 will be retained <br />to provide continued drainage and sediment control through the <br />reclamation liability period. Given contemplated mine closure, this ditch <br />will also remain as a permanent drainage structure and has been <br />. • . designed for the 10-year, 24-hour event. Designs for the north <br />- 7- <br />