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Mr. Michael Cunningham 2 <br />CDRMS <br />May 30, 2014 <br />become necessary. If the Operator does not wish to provide additional sediment storage <br />capacity at the southwest corner of the TSF at this time, they must agree to a stipulation to <br />provide sufficient additional sediment storage if adequate vegetation is not established on the <br />TSF slopes within two years. Please provide a written commitment to provide sufficient <br />additional sediment storage if adequate vegetation (as determined by the Division) is not <br />established on the TSF slopes within two years. <br />Response: <br />UMC agrees with the stipulation presented by the Division and commits to provide <br />sufficient additional sediment storage should adequate vegetation (as determined by the <br />Division) is not established on the TSF slopes within 2 years of the completion of the <br />TSF. <br />UMC's response to questions 10 -12 in the Second Adequacy letter dated 22 April 2014 are <br />considered adequate by the Division and are not repeated here. <br />New Comments <br />13. DR -2 and Upper Diversion Channel. Analyses in Appendix B indicate the Upper Diversion <br />needs to be two feet deep to provide adequate capacity. Drawing D -2, Upper Diversion <br />Channel — Section No. 4 dimensions the channel to be 1.5 feet deep. Please correct the <br />drawing to show the required two -foot depth. <br />Response: <br />The Section No. 5 detail on Drawing D -2 was revised to indicate Section No. 5 applies to <br />a portion of the Upper Diversion Channel, the East Diversion Channel, and the TSF <br />Spillway Channel. The Channel Report was revised for the Upper Diversion Channel for <br />Section No. 4 showing a capacity- maximum slope condition that models Upper Diversion <br />Channel along the 10% section of the upper road. See Appendix 1 <br />14. DR -2, TSF Spillway Channel. Appendix B indicates the TSF Spillway Channel is a 2 -foot <br />deep, riprap -lined triangular channel. There is no detail on Drawing D -2 for the TSF Spillway <br />channel. Please add a detail to Drawing D -2 and be sure the riprap called out is consistent <br />with that sized in Appendix B. <br />Response: <br />The Section No. 5 detail on Drawing D -2 was revised to indicate Section No. 5 applies to <br />a portion of the Upper Diversion Channel, the East Diversion Channel, and the TSF <br />Spillway Channel. The riprap in the channels was set at 10 inches so that only one size <br />of riprap is required across the site. See Appendix 2. Note that DR -1 is included in <br />Appendix 2 for reference. <br />15.. Appendix B, West Diversion Channel. Appendix B still has analyses (both stability and <br />capacity) for a maximum slope of 62.5 %. Please confirm there is no longer a plan for <br />constructing this steep of a channel and replace these two analysis sheets with the <br />