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A *130, 2013 C-1992-080/Carbon Junction Mine MLT <br /> Reconstructed Carbon Junction Drainage <br /> The team observed numerous issues with the disturbed portion of the Upper Carbon Junction <br /> Channel, located upstream of the riprapped permanent diversion channel: <br /> • An erosional gully, approximately six feet deep, has formed at the downstream terminus of <br /> the diversion berm. <br /> • Sediment generated by this erosion has created a physical barrier to the flow of the channel, <br /> and would result in flow being ponded upstream of the sediment fan. <br /> • The un-named tributary channel that enters the Carbon Junction drainage from the east is <br /> confined behind the diversion berm, rather than being allowed to flow directly into the main <br /> drainage. This would potentially contribute to continued erosion of the gully. <br /> • At the location where the diversion berm was breached in the fall of 2012, the profile of the <br /> channel is significantly steeper than what exists both upstream and downstream. Head- <br /> cutting of the channel could potentially result from this nick point. <br /> • The Lower Sump identified on the Mine Hydrology Map appears to have filled with <br /> sediment, and the site is now populated by narrow-leaf cottonwoods and willows. <br /> • Approved designs for this segment of the Carbon Junction Channel could not be located. <br /> • The Mine Hydrology Map approved with TR-II clearly shows that Carbon Junction was <br /> diverted just downstream of the lower slope of the North Pit, and that flow was to be restored <br /> to the original channel. Additionally, this map shows that the natural channel upstream of <br /> the diversion was affected by the disturbance of the North Pit. <br /> • The Division had identified some of these issues last year. In an August 29, 2012 letter to <br /> Oakridge, the Division had requested that a Minor Revision(s) be submitted to address these <br /> issues. However, due to number and complexity of items now involved, a Technical <br /> Revision will be required, as set forth in the Abatement Steps below. <br /> Number of Partial Inspection this Fiscal Year: 2 <br /> Number of Complete Inspections this Fiscal Year: 3 Page 4 of 7 <br />