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A *130, 2013 C- 1992 - 080 /Carbon Junction Mine MLT <br />tributary to Carbon Junction Canyon, and then traveled down the tributary to its intersection with <br />Carbon Junction Canyon, and explored the canyon a short distance downstream of the <br />confluence. Reclaimed Sediment Pond #2 was observed. The team then retraced its steps, <br />collecting measurements of the permanent diversion channel throughout its length. These <br />measurements consisted of channel gradient, channel width, and size of riprap used. <br />As we proceeded upstream from the permanent diversion, we noted the erosion that has occurred <br />on the southern side of the drainage. (This issue has been addressed in previous Division <br />inspection reports, beginning with March 29, 2013.) We continued to move upstream, along the <br />diversion berm which parallels the original channel on the south, passed beneath the toe of the <br />reclaimed North Pit, and eventually reached the undisturbed, native channel. <br />Designs for reconstruction of the Carbon Junction Canyon drainage were approved with TR -11 <br />in October 2002. Details may be found in pages 5 -8 thru 5 -17 of Section 2.05 (Operation and <br />Reclamation Plan). The approved design plan, profile, and cross section views of the Carbon <br />Junction channel and its environs appear on the following permit maps, also approved under TR- <br />11: Mine Plan Map, Site Cross Sections, Mine Hydrology Map, and Post Mining Topography <br />Map. (Note: the location of the shared permit boundary with the adjacent gravel pit, Ewing <br />Mesa Pit No. 1, was subsequently revised in July 2004 under TR -12.) <br />Permanent Diversion <br />The permanent diversion channel was stable; however, certain field measurements indicate that <br />the channel was not constructed as designed: <br />• The gradients of Segments 1 through 6 differed from what was shown on the Site Cross <br />Sections Map, with Segment 1 being steeper and the other five segments being generally <br />flatter than was specified, as seen in the table below. <br />Channel Segment* <br />% Grade <br />(Measured) <br />%Gradient <br />(Design) <br />1 <br />14.0 <br />7.30 <br />2 <br />1.4 <br />2.19 <br />3 <br />4.0 <br />5.31 <br />4 <br />15.0 <br />16.14 <br />5 <br />9.0 to 10.0 <br />9.78 <br />6 (lower) <br />1.0 <br />2.15 <br />6 (upper, to curve) <br />1.4 <br />2.15 <br />*As shown on Site Cross Sections Map, approved with TR -11 <br />• The riprap size was frequently coarser than what was required. <br />• For the culvert crossing of the permanent haul road (Segment 4), the design called for a <br />single pipe arch culvert, whereas twin 66" CMPs were installed. An as -built design for the <br />twin culverts was submitted in May 2007; however, the design was not revised in the permit. <br />Number of Partial Inspection this Fiscal Year: 2 <br />Number of Complete Inspections this Fiscal Year: 3 Page 3 of 7 <br />