2009-03-10_REPORT - M1977211 - Laserfiche WebLink

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4 immediately radioed the operators in the pit to "get out of there." The entire duration of the slide event was brief; reported to be only about 10 seconds. The toe of the rockslide mass buried the pit haul road and about two-thirds of the active pit bottom. At the time of the slide, the operators were either working on the east side or had quickly moved their equipment to the east side of the pit to avoid the slide materials, and escaped injury. Only a small portion of the slide mass encroached on the bench where the drill was operating so the drill operator also escaped injury. The driller wa able to evacuate the pit via the access road to this bench, but because the haul road ramp to the pit floor was buried by the slide, the loader and truck operators apparentlti evacuated the pit by climbing over a rock pile and/or a portion of the slide mass at the south end of the pit. It was estimated that raveling and sliding rock was heard in the pit for about 12 hours after the slide. / Miner and Eyewitness Accounts of Slope Failure We held a conference call on February 17, 2009, in order to obtain eyewitness accounts of the slide event. Those present in this conference call were: Paul Donahue - Technical Support, MWGED Eric Gottheld - Technical Support, MWGED Dustan Crelly - Denver Field Office Supervisor Tom Stefansky - Inspector, Denver Field Office, Rocky Mountain District Mac Shafer - Vice President, Aggregates, Transit Mix Concrete Chris Usry- Mine Manager, Transit Mix Concrete Mark Witthar - Loader Operator, Transit Mix Concrete John Bertrand - Network Administrator, Continental Materials Corp. (Resident near the quarry) Prior to and at the time of the slide, Mr. Witthar was operating a front-end loader at the pit floor. He was loading shot materials into trucks, working from east to west, removing material from the northeast wall in the southern portion of the pit. There had been some snowfall the previous night which was melting and creating wet conditions on the pit benches. No unusual conditions were observed; except that, one or two minutes before the slide event Mr. Witthar noticed a large muddy rock without snow cover on the pit floor about 250 feet south of where he was working. He was in the process of loading a bucket of rock into a dump truck operated by Mr. Roy Parino, when he noticed some rocks falling down the west highwall of the pit and the highwall starting to slough. Before he got a second bucket loaded, the highwall began to move. This was followed, seconds later, by the truck operator's radio call to "get out of there." The initial slide motion Witthar observed involved the upper part of the first bench above the pit floor, followed by the entire highwall "pushing out," while the pit floor appeared to heave about 1 to 11/2 feet. The subsequent slide motion resembled "cake