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Abstract <br />Oakridge Energy, Inc. prepared Appendix 5 -12 (Technical Revision No. 17) to address the Notice of <br />Violation (CV- 2013 -005) dated May 23, 2013. <br />Table of Contents <br />• Carbon Junction Permanent Diversion <br />• Upper Carbon Junction Channel <br />• Section A — Carbon Junction Permanent Diversion Analysis <br />• Section B — Upper Carbon Junction Channel Analysis <br />• Section C — Un -named Tributary Analysis <br />• Map C1.0 — Post Mining Topography <br />• Map C1.1— Carbon Junction Drainage Basins <br />• Map C1.2 — Permanent Diversion As -Built <br />• Map C1.3 — Upper Carbon Junction Profile <br />• Map C1.4 — Permanent Diversion Cross Sections <br />• Map C2.0 — Carbon Junction Channel Improvement Plan <br />Carbon Junction Permanent Diversion <br />Designs for the Permanent Diversion are found in Section 2.05 of the permit. The channel was <br />constructed in 2003 and 2006, and placed into service in 2009 when the sediment ponds were removed. <br />As -built topographic information for the Carbon Junction Permanent Diversion was obtained from a field <br />survey of the channel on October 2, 2013. Topography shown beyond top of bank of the permanent <br />diversion is from 2012 aerial mapping provided by the City of Durango. The aerial topography consists <br />of a 2 foot contour interval. The 2011 aerial topography and mine permit boundary are shown on <br />Exhibit C1.0. The Carbon Junction drainage basins are shown on Exhibit C1.1. The as -built configuration <br />of the Carbon Junction Permanent Diversion and associated cross sections are shown on C1.2 and C1.4. <br />It was noted in the DRMS inspection report dated April 30, 2013 that the Carbon Junction Permanent <br />Diversion was stable but was not constructed as designed in TR -11. Specifically, the channel gradients <br />were different than design gradients, the rip rap armoring was frequently coarser than what was <br />required, and the culvert crossing of the haul road used (2) -66" corrugated metal culverts instead of a <br />single pipe arch culvert. <br />As -built topography indicates that grades for the as -built channel are slightly different from the design <br />grades, generally ±1 %. A profile of the as -built channel is shown on map C1.2. The design rip rap for the <br />channel ranged from a D50 =12" to D50 =30 ". From a field investigation of the as- constructed channel, it <br />appears that the rip rap may be larger than designed, however, it is difficult to determine the actual D50 <br />without a proper geotechnical analysis. <br />From TR -11, the permanent diversion was designed to convey the 100 year peak flow of 346 cfs with 0.3 <br />feet of freeboard. A channel roughness coefficient of 0.044 was used. As part of this technical revision, <br />a HEC -RAS analysis was performed to determine the ability of the as -built channel to convey the same <br />100 year design event. The as -built survey topography was used to generate cross sections and <br />