Abstract: At about 4:40 p.m. on January 2, 1998, Employee #1 and an assistant chief engineer accessed a 46 ft tall modular metal scaffold inside an empty 11 ft 3 in. wide by approximately 52 ft tall milk silo to look at a spray disk that a contractor had just replaced. The two workers were standing on the top platform of the scaffold when a coworker turned on the clean-in-place (CIP) system. The coworker had meant to turn on the CIP system for a different silo and did not know that the jumper he had actuated was connected to the silo where Employee #1 and the engineer were located. As the water spray turned on, both workers started to descend the scaffold via the attached ladder. Employee #1 fell 46 ft, suffering a fractured left arm; loss of the full use of his left hand; damage to his left shoulder; damage to his T6, T8, and T12 vertebrae; lower back damage (his hips separated and came back together); and extensive tendon and ligament damage. A 6 in. metal plate had to be inserted in his left arm at the elbow. The scaffold had no guardrails; neither Employee #1 nor the engineer were wearing a safety belt and lanyard or other type of fall protection device.