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achieving a grass lined channel within approximately two years. When the maj ority of the watershed is at two <br /> years or more of vegetative growth,the grass lined channel is generally stable without requiring armoring. <br /> F7ue � � �� <br /> t e� m <br /> v6 d + 1 <br /> � t <br /> 4I� u <br /> A <br /> nl 'N'n'Mirw .M <br /> ..... <br /> t <br /> 77 I , <br /> Y ?gym <br /> ,Y.® <br /> e <br /> s <br /> Ili 4 <br /> q <br /> k I <br /> g <br /> I <br /> 11 <br /> ul Z <br /> Map 1: Areas associated with Phase I(SL18)bond release. The light orange areas comprise SL18. The purple circles indicate <br /> the locations of topsoil depth sampling DRMS conducted in 2017. Parcels AB16, FA16 and AB9 represent constructed <br /> drainages carved out of previous bond releases. The constructed drainage in parcel ZAB16 is integral to the parcel so not <br /> specifically delineated. <br /> Leading up to bond release,TMI utilizes a series of regularly spaced check dams. TMI presents design rationale <br /> and modeling results for drainageways in Appendix Q, Section XXXVII of the permit: Reconstructed <br /> Drainage Channel Design. Once built, these measures are left in place. The wide trapezoidal channel form <br /> results in shallow flow depths for the design storm,resulting in a small hydraulic radius that promotes low flow <br /> velocities. <br /> III. APPROVAL CRITERIA for BOND RELEASE <br /> Under Colorado's Permanent Program,the process of releasing the reclamation bond for a mine site is explained <br /> in Rule 3.03 and further described in the Division's 1995 Guideline Regarding Selected Coal Mining Bond <br /> Release Issues. For Phase I bond release,Rule 3.03.1(2)(a) states: <br /> "Up to sixty percent of the applicable bond amount shall be released when the permittee successfully <br /> completes backfilling, regrading, and drainage control in accordance with the approved reclamation <br /> plan." <br /> Permit Number C1981010 Prepared by: R.Reilley,MS,LISP <br /> SL 18 Page 7 of 22 <br />