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III. COMMENTS -COMPLIANCE <br />Below are comments on the inspection. The comments include discussion of observations made <br />during the inspection. Comments also describe any enforcement actions taken during the inspection <br />and the facts or evidence supporting the enforcement action. <br />• Channel dimensions appeared to exceed design specifications. Channel appeared to be stable <br />along most of length, with the exception of side-cutting in the steep segment near the southwest <br />corner of the fenced area. Also, there is minor down-cutting extending upstream from the upper <br />end of the riprap. These areas will need to be monitored, and maintenance will be <br />necessary if the reaches do not stabilize or if further head-cutting or side-cutting results. <br />006-SE1 Channel <br />This channel drains a relatively small watershed in the southwest portion of the "A" pit reclaimed area. <br />Design profile shows grades ranging from 3% to 10.5% along the upper and middle sections of the <br />channel, with a segment averaging 15.6% near the lower end of the channel. Designs specify a "V" <br />shaped vegetated channel 1,5' deep and 9' wide for segments with gradient between 3% and 10%. <br />Design for grade segments from 11% to 17% is a trapezoidal channel with 4' bottom width, 0.5' depth, 7' <br />top width, gravel substrate. <br />A section of grass lined channel extends for 150' or more upstream from the upper limit of <br />riprap. The section gradient was measured at 8%. A gully 8"-14" deep by 1' to 4' wide has <br />developed along this upper channel segment, and the gully continues up-gradient for a <br />considerable distance, extending toward the upper end of the watershed. Sections of the gully <br />were apparently previously repaired, but downcutting has recurred. It appears that the <br />constructed channel does not extend as high up into the watershed as depicted on plan <br />maps and profiles. If this is the case, channel will need to be extended up-slope in <br />accordance with approved design. Appropriate stabilization measures as described in <br />the approved rill and gully plan will be warranted, for gully segments that extend up- <br />slope, east of Design Point FF, as well as for Bullied segments of the vegetated channel. <br />• There is a temporary construction road that passes through the SE1 watershed and runs along <br />the crest of the south highwall reclamation slope. The road will need to be reclaimed <br />(scarified and seeded). <br />• Upper riprap segment of the channel was measured at 16% slope, which is within the design <br />range of Figure 20-1.1. Channel dimensions along the segment appear to exceed design <br />requirements, and the reach appears stable, with grass beginning to establish through the <br />riprap. <br />• Along the lower 150' segment of the channel down to the 006 Gulch confluence, flow appears to <br />have jumped out of the channel and eroded a gully along the outside of the riprap (Digital Image <br />2584). Minor repair is warranted along this section; channel depth appears to be less <br />than the design 0.5' in the location where flow escaped the channel. <br />Drainage Channel Summary <br />Maintenance is necessary in a number of locations along the inspected channels, where riprap has been <br />washed out, or where flow has scoured along the edge of the riprap. Channel shape (wide and shallow, or <br />convex cross-section) with inadequate armoring of channel sides appears to have contributed to erosion within <br />the channels in a number of segments, and regrading to establish design configuration with properly armored <br />sideslopes is warranted. In one location (006-SE1), the permanent channel will need to be extended higher into <br />the watershed to conform with approved design. Operator needs to perform maintenance including <br />10 <br />