Abstract: Employees were cleaning residue buildup on the inside of a 605-foot high chimney of a lignite coal power generating plant. They were using water to wash off as much of the residue as possible. A very large mass of residue, about 15 feet thick and 30 to 40 feet in diameter, was located where the breech enters the chimney. Cleaning had progressed from the top down to the breech area. A firefighting type water hose was being used to apply water to the massive buildup, when the large mass suddenly broke loose and fell 80 to 100 feet to the bottom of the chimney. As it hit the bottom, the brick inner liner collapsed, causing the concrete outer shell to collapse also. Employee #1, who was tied off to a scaffold in the breech mouth was crushed by the falling debris. Other employees who were not tied off were blown away from the chimney by the air blast created by the falling brick.