_INSPECTION - C1982057 (61) - Laserfiche WebLink

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III. COMMENTS - COMPLIANCE Below are comments on the inspection. The comments include discussion of observations made during the inspection. Comments also describe any enforcement actions taken during the inspection and the facts or evidence supporting the enforcement action. the pond in-slope slump will need to be addressed within the context of the slide remediation plan for the entire slide complex in the vicinity of Pond 016/016A and the nearby shrub plot. A complete technical revision application addressing remediation of the slide complex in the lower 016/016A watershed will need to be submitted no later than July 15, 2010. • Pond 016 was observed on the afternoon of 4/28/10; discharging clear flow over the top of the riser. As noted for Pond 016A, there was some woody debris in the trash rack that needs to be cleaned out. • Pond 017 was observed on the afternoon of 4/28/10; discharging clear flow over the top of the riser. Most reclaimed area stock ponds were full or nearly so, due to recent snowmelt runoff. The spillway outlet channel on Stock pond T-25 in the lower Pond 17 watershed had undercut the TRM channel liner. Riprap installation appears to be warranted at the location. Backfill and Grading Permanent Channels and Hillslope Erosion Rill and tully repair work will be required in numerous locations, including permanent channel segments and hillslope areas. In the older reclamation sites within the original permit area, erosion problem areas are primarily associated with channel locations and slope areas that have been subject to previous repairs, and/or slope areas subject to concentrated runoff from road ditch outlets or culverts. Slope areas that have been subject to repeated erosion due to concentrated flow should be repaired as stable tributary channels (riprapped or TRM- lined as appropriate), incorporated into the permanent drainage network. Channel and hillslope areas that will require erosion repair are more widespread in the South Extension Area, due to the extent of more recent reclamation. Numerous erosion control "surge structures"were constructed along the primary permanent drainage channels in the 016 and 017 watersheds during the 2009 field season, in response to significant channel erosion caused by extremely heavy runoff in the spring of 2009. Drainage channels that had been extensively damaged by the heavy runoff were regraded and repaired with new riprap and TRM liner installation. The surge structures appear to have largely functioned as designed this spring. They obviously had checked runoff and temporarily retained water, but the dewatering pipes had functioned properly and the structures did not contain standing water at the time of the inspection. The permanent channels in the 016 and lower 017 watersheds were generally in good condition along most reaches observed. However, channel maintenance will be necessary in a number of locations along various channel segments in the two watersheds, particularly in locations immediately downstream from surge structure discharge pipe outlets. In several locations observed, TRM liner in these sites had been undercut or flow had scoured into the channel side slopes, and repair including regrading and heavier armoring will be necessary. Similar erosion was observed in the channel segment just downstream of Stock Pond T-27. These sites and similar locations will need to be carefully checked and repaired during the 2010 field season. Hillslope gullies will need to be repaired in accordance with the approved Rill and Gully plan. Areas that have been subject to recurrent erosion due to concentrated flow will need to be repaired as stabilized tributary channels, incorporated into the permanent drainage network. SCC will need to thoroughly inventory the mine site for hill slope rills and gullies and permanent channel areas that require repair, for inclusion in the annual Rill and Gully Map and Stabilization plan to be submitted by June 1, 2010. 6