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Several hundred feet up-drainage from the oil well road, an apparent settling crack was observed <br />along the lower portion of the slope north of the channel, running parallel to the channel for 200 to <br />300 feet. The crack was 1-2 inches wide, and appeared fairly deep in places, although there was no <br />apparent movement associated with the crack. No pending problems are apparent but this area will <br />be monitored in the future. <br />In various locations, hillslope rills and minor gullies with segments up to 12-16" deep were observed, <br />where stabilization measures are warranted. Slope erosion areas which will not be excluded from the <br />proposed decision, but where maintenance in accordance with the approved Rill and Gully plan will <br />need to be applied are listed below. These features and locations are further described in the SL-2 <br />inspection report dated January 4, 2010, and relevant photos are attached to the report. <br />• Two gullies subject to past repair efforts on the slopes of the upper 006 watershed, between <br />LU3 and the Ridgeline Access Road, where downcutting has reinitiated in previous repair <br />areas. Channel shaping and TRM liner installation are warranted; <br />• Intermittent gully along ridge west of powerline, between NE3 and NE4 drainages; <br />• A couple locations on slopes adjacent to Channel 006-E1 (one gully upstream and one <br />downstream of the 006-E2 confluence); <br />• Rills along a maintenance route on broad ridge between 006-E1 and 006-NE3; <br />• Rills on 006 Gulch hillslope below Ridgeline Access Road in Culvert PM-17 vicinity <br />• The broad lower slope areas between 006-NE2 and 006-NE1, which drain toward the Oil <br />Well Access Road, have been subject to rill erosion and associated repair over several years. <br />The area is stabilizing, but active rills persist in several locations. Low impact erosion control <br />measures (hand placed rock or straw wattle checks and limited interseeding) are warranted. <br />There is a small depression within a fenced planting area along the eastern ridgeline in the Sage <br />Creek watershed that drains into Pond 15. The depression apparently formed from minor settling <br />following initial regrading. The depression holds a shallow pool of water from snowmelt -and rainfall <br />during portions of the year, and a diverse vegetation community is becoming established, with <br />wetland species such as cattail and willow in the center, wetter areas, with upland species including <br />planted aspen and tall shrubs in more mesic sites, and seeded big sagebrush on steeper slopes and <br />exposed ridgeline areas both inside and outside the fenced zone. Given the benefits of the shallow <br />depression with respect to vegetation community diversity and wildlife habitat, the Division approves <br />retention of the feature within SL-2. <br />One significant area of mass instability was noted on a reclaimed highwall slope in the upper 006 <br />Gulch watershed. The regraded "A" Pit highwall slope located to the south of the upper section of <br />006 Gulch, up-slope and southeast of the Ridgeline Access Road has been subject to two episodes of <br />instability. See Figure 3 for the location of this area. The slope failed following original reclamation <br />grading, resulting in significant displacement and a primary scarp over 8' in height. Following <br />geotechnical investigation and development of a remedial plan, the failed slope was graded to a <br />reduced gradient and fully reclaimed in 2004. A smaller slope failure occurred in the same location <br />in 2008, creating a tension crack extending for over 200' across the slope, with a scarp 2' to 3' in <br />11