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3 <br />The pit slopes are currently about 100 feet high on the east side and about 600 feet high <br />on the west side. The open-pit is roughly rectangular in shape, with the long axis <br />generally along the north-south direction and its short axis along the east-west <br />direction. The overall dimensions of the quarry at the top of the east pit slope are about <br />1,400 feet east-west and 3,000 feet north-south. <br />In 1993, a blaster, working from a bench about halfway up the west side of the pit, <br />created a large unstable "hole" in the north central part of this pit slope. The reason for <br />creating this hole was not clear, but it created an unstable slope condition. To mitigate <br />the unstable. condition, this hole was subsequently filled with soil-like dark red <br />decomposed granite which underlies the natural slopes above the pit. The decomposed <br />granite was dozed over the edge of the pit slope from a bench excavated into the <br />natural slopes above the pit until the hole was filled with an angle-of-repose deposit of <br />soil. This soil-filled hole in the pit slope can be seen in Figure 1, an undated USGS aerial <br />photo, probably taken about 2 years ago, and in Photo No. 1, which the mine operator <br />reportedly took about 3 years ago. <br />At the time of the slope failure, active mining was occurring in the southern portion of <br />the pit and on the adjoining bench immediately north at about 30 feet higher in <br />elevation. The southern portion of the east-facing pit slope had been reclaimed by <br />partial filling of the benches with a wedge of soil that was revegetated. This initial <br />reclamation work was also being started along the top of the northern part of the east- <br />facing pit slope, where a bench was being cut into the natural slope that is underlain by <br />decomposed granite. Working from this bench, the operator is planning to flatten the <br />pit slope to 32 degrees (about 1.6H:1V) and cover the slope with the decomposed <br />granite material onto which vegetation would be re-established. This work would <br />require encroachment onto about 26 acres of Pike National Forest Land at the top of the <br />slope; so it was to be done under coordination with the USDA Forest Service. <br />Operator's Account of Slope Failure <br />Mr. Chris Usry provided an account of the slope failure. The personnel present in the <br />pit at the time of the accident were not present during our site visit. The slope failure <br />occurred at about 7:13 a.m. on December 2, 2008. A loader operator and truck driver <br />were in the lowest part of the pit loading and hauling rock from the pit, and a driller <br />was drilling shot-holes on the bench to the north of the loading operation. Mr. Usry <br />stated he normally performs a highwall examination that includes examining the top of <br />the pit slope, but he had not done the examination yet on the day of the failure. <br />A water truck operator on the road near the mine office and the loader operator in the <br />pit noticed the slope movement at about the same time and were primarily alerted by a <br />roaring noise they described as sounding like a jet airliner. The water truck operator