Abstract: At approximately 8:00 a.m. on November 16, 1990, Employee #1 and a coworker told the plant operator they were going to go up to the hopper and clean it, because it would be the last day of work for a while. When the two men arrived at the hopper they walked out onto the hard-frozen sand to start breaking it up with a mattock and shovel. As they broke up the sand, the pile on which the men were standing broke loose. The discharge conveyor belt under the hopper was still running and Employee #1 became trapped. The conveyor line was shut off immediately and he was rescued less then an hour later. The only injury he sustained was a strained knee. Neither man had any fall protection.