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INTRODUCTION The Rockcastle Company Grassy Gap Mine Sediment Pond Inspection October, 1991 In accordance with the existing mining permit for The Rockcastle Company's (ROCKCASTLE) Grassy Gap Mine in Routt County Colorado, an inspection of the sediment retention ponds was performed on October 1, 1991. The inspection was completed by Robert Peterson, ACZ Inc. Engineer in behalf of ROCKCASTLE. The existing 4 ponds were inspected for structural problems related to the embankment and the facilities, evidence of erosion, and other hazardous conditions. The inspection included a survey of the sediment levels in Pond 5/6 using a hand level and a survey rod. Following are the results of the October, 1991 sediment pond inspections. POND 2 The incised pond west of the reclaimed Pit 2 contained no measurable water, however the bottom was slightly moist and cattails were present. The trapezoidal riprapped outlet channel showed no signs of recent discharge and appeared to be intact and functioning properly. Due to the steep sideslopes, vegetation was limited to mostly native grasses and few low shrubs on the embankment crest. It was noted that the southeast facing slope had very dry and loose soils. Several burrows and animal travel paths down into the pond were noted causing some erosion of the steeply sloping embankment side. There were not gullies, cracks, slides, or seepage was observed on the embankment sideslopes. The sediment level in the pond was not measured during this inspection. Due to the small amount of precipitation for the area during the summer months and evidence of minimal inflow as observed on a monthly basis, the sediment level has not changed significantly from that measured in June, 1991, approximately 10 feet below the invert of the spillway. The accumulated sediment is considered to be negligible compared to the storage capacity of the pond. 1