Laserfiche WebLink
Sedimentation Pond Retention/Reclamation, which accompanies these <br />responses. <br />The northwest side of the Pit 5 East Ridge drains to disturbed area <br />collection Ditch 5-3 which routes disturbed area runoff to Pond 5/(i. <br />Rockcastle proposes to retain both this ditch and Pond 5/6 as <br />permanent drainage features, and has consequently designed Ditch 5-3 <br />to safely pass the peak flow from a 10-year, 24-hour storm event with <br />adequate freeboard. Appropriate design documentation accompanies <br />these responses as Appendix A, Drainage Design Information. <br />Review of aerial photographs indicates that previous mapping of both <br />disturbance areas and ditch locations for Pits 5 and 6 may not be <br />entirely accurate. The hand-drawn map referenced in the response to <br />Comment 1 above reflects appropriate mapping changes based on <br />photographic documentation, As reflected by the revised mapping, it <br />appears that the present slope configuration will direct surface runoff <br />from all disturbance areas, including reclaimed topsoil/overburden <br />stockpile areas, to Ditch 5-1. Ditch 5-1 extends further west than <br />previously shown, with actual ditch configuration and extent as depicted <br />by the Postmining Drainage and Sediment Control Map, (Map R-1), <br />4) We can accept the ACZ plan regarding the Contour Ditch No. 5, in place <br />of armored channels. This change is based on field observations that <br />Itillslopes below the proposed ditch are stabilizing with healthy vegetation. <br />Please insure that field implementation includes a smooth transition area <br />where rite ditch intersects the norlteast road ditch. <br />Response: No response necessary. <br />5) Please address the question, V//, 22 in the April 24, 1991 letter, regarding <br />the sedimentation analysis merltods used for the pond removal <br />-4- <br />