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1 <br />GoFF_ E SURVEYING INC <br />1 <br />1 <br />1 <br />1 <br />1 <br />136 ROCK POINT DRIVE PO BOX 97 DURANGO, COLORADO 81302 <br />October 7, 2013 <br />Ms. Marcia Talvitie, P.E. <br />Environmental Protection Specialist <br />Colorado Division of Reclamation, Mining and Safety <br />Coal Program — Durango Field Office <br />701 Camino Del Rio, Room 315 <br />Durango, CO 81301 <br />Office 970.247.1705 <br />Fax 970.247.1710 <br />www.goffengineering.com <br />RECEIVED <br />OCT °I C j"U13 <br />DWISION OF RECLAMATION <br />MINING AND SAFETY <br />Re: Technical Revision 17 Application to the Carbon Junction Mine permit (CDMG permit C -92 -080) <br />addressing Notice of Violation (CV- 2013 -005) <br />Dear Ms. Talvitie: <br />Oakridge Energy, Inc. is submitting this technical revision to the Carbon Junction Mine permit to address <br />the Notice of Violation dated May 23, 2013 and DRMS adequacy comments from the initial review of <br />this technical revision dated September 20. The technical revision includes the following items required <br />from the abatement steps listed in the Notice of Violation: <br />1. As -built information of the Carbon Junction Permanent Diversion configuration. <br />2. Updated post - mining topography map. <br />3. Map of Carbon Junction drainage area. <br />4. Channel Improvement Plan for the reestablishment of the Upper Carbon Junction Channel and <br />un -named tributary entering from the east, and reclamation and stabilization of the Carbon <br />Junction Temporary Diversion and gully erosion. <br />Carbon Junction Permanent Diversion (Abatement Step #1) <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 CIA. 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 />