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The intent of the re- grading of the temporary diversion is to provide a mostly uniform slope along the <br />easterly bank of the Upper Carbon Junction Channel, returning it to its near historic cross section. <br />Grading operations should be done in a manner to minimize import/export of material and to minimize <br />disturbance of existing vegetation as much as possible. All areas disturbed during construction activities <br />' shall be covered to a depth of 6" with native topsoil material and re- seeded with a native grass mixture. <br />All work shall be in accordance with the Colorado Division of Reclamation, Mining and Safety, <br />Regulations of the Colorado Mined Land Reclamation Board. <br />A HEC RAS analysis of the Upper Carbon Junction Channel was conducted using the 10 year design flow. <br />The 10 year design flow of 49.0 cfs was determined for the basin using the HydroCAD modeling <br />' software. The HEC RAS results indicate that 10 year flow velocities along the channel will be below 5 <br />fps. Therefore, erosion control measures including riprap will not be required. This includes the steeper <br />portion of the channel (approx. 12 %) between Sta. 34 +00 and 36 +00 which yielded velocities between <br />3.5 fps and 4.54 fps. HydroCAD outputs and HEC RAS cross sections with water surface elevations are <br />included in Appendix B. <br />' Enclosed are the public notice, a revision application, Exhibits (C1.0, C1.1, C1.2, C1.3, C1.4, C2.0), HEC - <br />RAS cross sections and the 2007 culvert analysis. If you have any questions, please do not hesitate to <br />contact me. <br />J ely, <br />rries, P.E. <br />' Goff Engineering & Surveying, Inc. <br />Enclosures: CDRMS Revision Application <br />' Proposed Public Notice TR 17 <br />Exhibits C1.0, C1.1, C1.2 -C1.4, C2.0 <br />Appendix A <br />1 <br />1 <br />ra, _ <br />