I have 17 years experience in a glass factory. Family has over 140 years experience total. Have seen many tank drains. Rumor was told about a tank break that emptied itself in the basement unexpectedly , there was a man sweeping up when it happened, He was never found, nor any trace of Him. Also have 9 months experience in a steel mill, furnace dropped the bottom on 300 tons of liquid steel. A group of old timers were along side the floor about 100 yards away when it let go. They started running over very rough ground with difficulty. We were laughing about it until the steel almost caught up to them. If they had not started running when they did the outcome would have been different.