Abstract: Employee #1 was a driver for Waste Management, Inc., engaged in servicing and renting out portable toilets at customer sites. At approximately 5:30 a.m., on Monday, June 26, 2000, he was inside the yard, getting ready for his route. Since his regularly assigned truck was being serviced, he checked out a spare vacuum truck, #1204 that had been assigned to him by a shop mechanic. This was a 2-ton International pump truck, model S1700, with a Tank-n-7656, model PV1400 presvac system, serial #1094-4688. As part of his routine, Employee #1 filled the truck with gas and then drove it 50 yards to the water fill station. He set the parking brakes and climbed on atop the tank to fill it with fresh water tank. Employee #1 was opening one side of the water fill hatch when the pressure inside the tank compartment pushed out the top cap with great force. The cap flew up and hit him under the right jaw. Employee #1 was thrown backward onto the top of the cab, from where he rolled off onto the hood and then onto the ground. A coworker saw him roll down the front of the truck and caught his arm before he landed. The coworker laid him on the ground, saw that he was bleeding profusely from his mouth and face, and summoned another coworker to run to the office for help and to tell the supervisor. Employee #1 suffered a serious internal mandible fracture and a right condyle fracture. He was transported by the local paramedics to the emergency unit at Presbyterian Intercommunity Hospital, where he underwent surgery and remained under treatment for four days. Subsequent investigation determined that the accident was caused by the use of compressed air at a pressure that exceeded the safe level for the container tank. In addition, Employee #1 did not have proper training in the safe operation of a pressurized tank and a necessary safety valve was missing.