_INSPECTION - C1982057 (77) - Laserfiche WebLink

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July 6,2011 C-1982-057/Seneca II-W Mine SLB There are two slides in the east end of the A pit reclamation, and a mudflow from the well pumphouse down to Haul Road A. The cut slope above LU-2 is exhibiting soil creep. CGS and NWCC suggested that no repairs be undertaken on the small slides at the east end of the A pit reclamation. At the time of the inspection,the operator had initiated repairs to the well pumphouse slide; CGS recommended installation of rock toe drains in addition to the work already performed. The operator proposed reclamation of LU-2; the Division and CGS agreed that this would be a good solution to the instability in this area. In the immediate vicinity of Pond 006,there are two slides on the east(inlet side)corners of the pond,and several smaller slides along Haul Road A between the pond and the facilities area. The operator was in the process of narrowing the haul road to its approved postmining width,which will result in the repair of the surface slides between the pond and facilities area. The road will be realigned further east between the A/B pits and Pond 006 at the intersection with the oil well access road(RCR 53A) so that it is moved away from the pond inlet slide areas. Downstream of Pond 006, in the 006 Gulch, a section of the Mine Entrance Haul Road failed(subject of Notice of Violation No. CV-2001-00 1). At the time of this inspection,material from the slide had been removed from the stream channel and repairs were complete. A technical revision for this area is currently under review; no further action is recommended at this time. There are small slides on the slope between the facilities area,Haul Road A, and Pond 006. The operator proposed realignment of the road and lessening of the slope to promote stability in this area. The Division and CGS agreed that this would be a reasonable approach. In the vicinity of the upper A Pit and neck pit areas,there is a recurring slide across an old pit ramp. This season marks the fourth time this particular area has moved. CGS and NWCC suggested careful grading of the upper scarp to assist in reaching equilibrium(recommended small, lightweight equipment or hand shoveling), installation of two toe drains,and installation of a surface water conveyance ditch to move water off of the slide area and prevent infiltration to the extent possible. There are cracks across Light Use Road 5,between the neck and the upper Pond 016A drainage area. During the inspection,it was determined that these cracks are the lower reaches of a larger slide area to the east,in an area undisturbed by mining. No action was recommended for this area at this time; SCC should repair the road as necessary when cracks develop. The slide areas in the vicinity of Pond 016 and Pond 016A were inspected. There are three separate failure areas in the vicinity of the ponds: the slope on the north side of Haul Road J, on the north side of Pond 016A,the slope between Haul Road J and Pond 016A at Culvert K-1,and the slide at the base of the shrub plot. Technical Revision No. 73, approved July 1, 2011 will address repairs to the damage in this area. The plans were reviewed briefly during the inspection; no changes were proposed. There is a small slide along Haul Road K,approximately 1000' south(along the road) from culvert K-1. No remediation was recommended for this area. There is a slump and linear crack above Pond 017,on the north side of the drainage,beginning at the pond inlet, and extending about 150' up the slope. Approximately 75' of the fissure extends into an undisturbed area. The toe of this slump and another seep area adjacent to Pond 017 were both weeping. There are also small slumps in the PM channel between T25 and Pond 017,and at the inlet of T25. The operator and CGS discussed removal of the T25 stock tank to prevent constant wetting of the slope and to possibly allow the unstable areas to dry out. There are two small slumps on the north slope above the upper reach of PM3. No action was recommended for Number of Partial Inspection this Fiscal Year: 3 Number of Complete Inspections this Fiscal Year: 0 Page 3 of 6