Abstract: At approximately 2:30 p.m. on September 9, 1990, Employee #1, of the Water Quality Control Plant for the cities of South San Francisco and San Bruno, was using a Komatsu tractor, model #D3IQ-16, to empty sludge beds in the far east area of the plant. The tractor had not been used for about 4 years, and was then used 8 hours a day for about 6 weeks prior to the accident. Employee #1 stated that this tractor was known to have an overheating problem and that it had to be cooled two to three times per hour. As he was removing the radiator cap to cool the engine, he was deluged by hot water and dove into a pile of sludge. Employee #1 managed to get into his truck and drove about 1/4 mile to his supervisor. Employee #1 suffered second- and third-degree burns on his left arm, torso, and face. He was transported by the South San Francisco Fire Department to Kaiser Hospital, where he was treated and released. He lost about 11 days of work. Employee #1 stated that he removed the radiator cap because he thought it would have a safety feature that would release the pressure before allowing the cap to be removed. Industry safety orders do not require this type of cap. The employer was cited for not maintaining equipment in a safe operating condition.