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Name of Addressee <br />Page 2 <br />Date <br />5. On page 2.05.3(3)-36, the BB Road Detour Design Details have changed. The current permit <br />has 21 bullets and the proposed revision has 16 bullets. Since the detour road has already been <br />reclaimed, please explain why the design details are being changed. <br />Attachment 2.05.3(3)-28 <br />1. Based on the information presented in the proposed Attachment 2.05.3(3)-28 the structure details <br />associated with proposed ditches C4A and Ditch Pond 018 East were completed without <br />freeboard. There was no discussion in the provided text to serve as a justification not to include <br />freeboard in the proposed ditch designs. Per Rule 4.05.3(7)(b), diversion design shall <br />incorporate freeboard no less than 0.3 feet. Please provide detail designs which include <br />freeboard of no less than 0.3 feet for the proposed ditches C4A and Ditch Pond 018 East or <br />provide a justification to the Division discussing the reason designs without freeboard meet the <br />requirements of Rule 4.05.3(7)(b). <br />2. Based on the information presented in the proposed Attachment 2.05.3(3)-28 the Pond 018 <br />design details, it appears that proposed Pond 018 is incorporating a single emergency spillway. <br />Per Rule(s) 4.05.6(3)(c), 4.05.6(4), and 4.05.9(2)(a)(ii), the sediment pond may be designed to <br />provide for a single open -channel spillway, in lieu of a combination of principal and emergency <br />spillways if the spillway is of non -erodible construction or is earth -lined or grass -lined and <br />designed to carry short-term infrequent flows at non-erosive velocities where sustained flows <br />are not expected. The proposed Pond 018 design proposes a single earth -lined or grass -lined <br />spillway; as such, please provide information in the proposed text, pond design, or response to <br />this adequacy comment discussing the justification that the spillway as proposed is designed to <br />carry short-term infrequent flows at non-erosive velocities. <br />If you have any questions or need additional information, please contact me at (303) 866-3567 ext 8142. <br />Sincerely, <br />Aw� 4--L <br />Brock Bowles <br />Environmental Protection Specialist <br />brock.bowles@state.co.us <br />