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preparation for excavation and repair of the embankment. He also contacted me on the afternoon of 11/18. The operator was able to pertorm the excavation and reconstruction of the embankment during a period of extremely cold weather, during which frozen conditions precluded runoff from disturbed mine areas into the pond. It appears that no actual environmental damage occurred. Fault It is not entirely clear to me what factors caused the instability. It seems possible that leakage from the buried spillway pipe may have contributed. The pond embankment had been in place since the early 1980's, and was originally certified by P.E. William Anderson in July 1983. There was a large flood event in 2001 that completely filled in the pond and caused some erosion of the embankment, but there had been no indication to my knowledge that the flood compromised the integrity of the embankment. The pond was excavated following the flood, and was certified by P.E. Jim Stover in March 2002, April 2003, and March 2004. I inspected the mine on October 13, 2004, and I did not observe any cracking or slumps on the embankment. I noted in the report that "the sediment pond appeared to be properly maintained and functional" and that "water level in the sediment pond appeared to be approximately 10 inches below the primary spillway invert". Apparently, shortly after that inspection there was significant inflow to the pond, and the primary spillway pipe inlet was submerged for some period of time. The 8" PVC spillway pipe had a gated valve at the outlet, so there would have been water in the buried pipe. At some point in late October, the operator noticed a very small area of settling at the downstream toe of the embankment adjacent to the primary spillway pipe outlet (based on what operator representative Rodney Head described to me). They excavated a trench into the embankment in the immediate area of the settling and for a distance along the buried spillway pipe, but based on what Rodney Head described to me on 11/19, there was no observed seepage through the embankment or indication of piping erosion. I was not aware that small holes had been detected in the spillway pipe until I saw Jim Stover's Oct. 28 pond inspection report. Jim subsequently indicated in his email that the holes had been repaired, and the pipe re-buried after his inspection. It would appear that the small settling feature at the toe of the embankment that the operator observed in late October may have been an indicator of the serious instability that became apparent with the cracking and large scale settling in mid November.