_INSPECTION - C1982057 ‎(61)‎

• Permit No: C1982057
• IBM Index Class Name: INSPECTION
• Doc Name: Inspection Report
• Inspection Date: 4/27/2010
• Email Name: DTM
• Email Name: SB1
• Media Type: D
• Archive: No

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.
Slides and Damage
Two areas affected by significant landslides in the past have been held out of the area that the Division is
proposing to approve within Phase I bond release SL-2. One of these slide areas is the slide complex in the
lower 016/016A drainage of the South Extension area, described previously in the Hydrologic Balance section of
this report. As noted, there has been additional movement this spring on the in-slope to Pond 016A. As further
noted, a remediation plan based on geotechnical and hydrologic evaluation of the slide complex is being
prepared by SCC, and a complete technical revision application addressing remediation of the slide
complex will need to be submitted no later than July 15, 2010. This extension (from March 31, 2010) is to
allow sufficient time for field survey and assessment as warranted to incorporate the new slide on the Pond 016A
in-slope into the remediation plan.
The second slide feature that was held out of the SL-2 proposed approval area is located on the reclaimed "A"
Pit highwall slope, on the NW facing slope southwest of the upper 006 Channel segment. The slope had failed
several years ago and was regraded to a lesser(approximate 30%)slope, by reducing the slope crest elevation.
Parallel cracks and bulging subsequently developed due to renewed slope movement, and the area was again
regraded in the fall of 2009. Cracks and bulging have reappeared this spring, in the same approximate location
on the slope. The primary crack is located approximately midway down the slope, is approximately 125 yards
long, with up to approximately 1' of displacement evident. A smaller crack and bulging is evident approximately
30 to 50 feet below, and roughly parallel to the upper crack. Assessment of the factors resulting in the continued
instability of the slope will be warranted during 2010. SCC will need to assess the factors resulting in the
continued instability of the slope and present a conceptual remedial plan within an addendum to the
2010 Rill and Gully Plan, no later than July 15, 2010. The slope grading performed last fall was completed in
November. Due to significant snowfall as the topsoil spreading was being completed, only the upper half of the
slope was seeded in the fall, and slope roughening was not implemented, with the exception of minor
roughening from dozer cleat marks. The cover crop seeded in fall along the upper slope had only very recently
germinated, and the lower slope was seeded only within the last couple weeks as the snow was melting off.
Shallow rills had formed along the lower portion of the slope from snowmelt. SCC will need to take
appropriate measures as necessary to provide for soil protection and prevent gully erosion on the
slope. Given the fact that the slope has been seeded, application of certified noxious weed-free straw
mulch,Woodstraw or equivalent,wood fiber hydromulch, or rolled erosion control products would be
appropriate options.
The area of the eastern ridgeline in the former neck pit area of the South Extension has been subject to
landslides and repair work in the past, specifically the corridor along the Ridgeline light use road (LU4), between
culvert PM-12 and PM-10. The slide repair slopes showed no evidence of renewed movement, and remedial
diversion and drainage structures including the PM-4D TRM channel and temporary flex pipe appear to have
functioned well and remain in good condition. Remnant snow drifts were still present adjacent to the road at the
crest of the primary slide repair zone, at the upper end of PM-4D.
An area was checked where minor cracks and slumps were repaired in the early summer of 2009 on the south
facing reclaimed highwall slope to the north of the lower end of Channel 005-E1, in the former"D" Pit area.
Repairs have held up, with no renewed cracking or slumping. However renewed cracking was observed in the
vicinity of a seep location on the slope to the south of the point where 005 Gulch enters Stock Pond T-18. A
crack in this location had been graded over in the summer of 2009, but has re-opened. At this time, the crack is
narrow, approximately an inch wide, and forms a semi-circle approximately 150'wide. Soils in the immediate
vicinity were saturated, possibly due both to snowmelt and groundwater seeps. This area will need to be
assessed over the course of the growing season to determine if remedial measures are warranted.
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