Abstract: At approximately noon on August 19, 1988, employees were cleaning the liner of a man-made lake in preparation for filling the lake. An employee needed to enter a vertical 24 foot manhole to close a gate valve so that the lake would be closed and could then be filled with water. Employee #2, a superintendent, entered the 24 in. wide manhole. Employee #3, the foreman who noticed that Employee #2 was having a problem, yelled at Employee #1, another superintendent, for help. Employee #3 entered the manhole, followed by Employee #1. All three employees died of asphyxiation. The manhole had been in operation since January 1988. There was water and brown matter in the bottom of the manhole. The company had no confined space entry procedure. No measuring equipment had been used to detect toxic or combustible gases and oxygen levels. No rescue equipment or procedure was available. No mechanical ventilation was used. The weather was hot, with temperatures in the 90s.