Abstract: On February 8, 1992, Employee #1, a newly hired utility worker for GNU Inc., was instructed by his supervisor to sprinkle water on a molten slag mound that was smoking. The supervisor then left the area to attend to another assignment. The hose Employee #1 was using did not reach the mound, so he asked a coworker what to do. The coworker instructed Employee #1 to get a bucket and fill it with water, then pour it onto the mound. When Employee #1 did this there was a violent reaction and a loud explosion. Employee #1 slipped and fell, fracturing his arm and sustaining burns on one leg. Employee #1 had received no instructions regarding this assignment, and he had no idea that pouring water on a molten slag mound would create an explosive reaction.