Abstract: Employee #1 was using a D-7 Caterpillar bulldozer to spread fill material over ice in an abandoned gravel pit. The thickness of the ice and the depth of the water beneath it had been checked by cutting holes about three-fourths of the way across the approximately 600 ft by 600 ft pit. The test holes revealed the ice was about 2 ft thick, but at some points touched bottom and at others had 3 to 4 ft of water beneath it. There was a sudden drop-off under the ice, where there was about 15 ft of water under it instead of 3 to 4 ft. At this drop-off point, the back of the bulldozer slipped into the pit and was completely submerged. Employee #1 drowned.