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Forrest Luke, TMI <br />Page 6 <br />7/29/2014 <br />d. Division's Response: This item is considered resolved. <br />4.08.1 Surface Water <br />23. Trapper did not submit detailed designs for post - mining drainage channels, as required by <br />Rules 2.05.3(4), 4.05.3(1), 4.05.3(1)(e), 4.053(7). <br />a. Rule 2.05.3(4)(a) — A general plan and detailed design plan shall be submitted for each <br />sediment pond, impoundment, other treatment facility and diversion proposed to be <br />constructed within the permit area. Please provide detailed design plans for each <br />postmining drainage channel. <br />b. Rule 4.05.3(1)(e) — channels must be designed, located, constructed, maintained, and <br />used to minimize adverse impacts to the hydrologic balance, and to be stable. Trapper <br />has offered details on how the channels might be constructed and maintained, but has not <br />provided specific design information. Please provide design information for each <br />postmining drainage channel to include the minimum channel dimensions and details of <br />any required velocity reduction measures. The dimensions and channel properties must <br />be based on the anticipated runoff for each specific watershed, based on watershed size, <br />topography and cover; the design precipitation event; runoff potential, etc. <br />c. Rule 4.05.3(7): <br />v. channel linings, including channel riprap, shall be designed using standard <br />engineering practices to pass safely the design velocities. Please provide design <br />information for each postmining drainage channel to include the minimum <br />channel dimensions and details of required velocity reduction. The dimensions <br />and channel properties must be based on the anticipated runoff for each specific <br />watershed, based on watershed size, topography and cover; the design <br />precipitation event; runoff potential, etc. <br />vi. Freeboard shall be no less than 0.3 feet. Please provide details on the proposed <br />channel dimensions so that the Division can determine whether the designed <br />channels maintain the required freeboard. <br />Trapper must submit the information required in Items (a) through (c) for all postmining <br />drainage channels to be constructed, completed, or reconstructed during the current <br />permit term. <br />d. Trapper's Response: Trapper is still working on a response to this comment. We have <br />encountered problems with a consultant engaged to advise us on this issue and the work <br />is still not complete. <br />e. Division's Response: This item is still outstanding and will need to be addressed prior to <br />the approval of PR7. <br />