Abstract: Six employees were injured when a drum became pressurized to the point it ruptured. The system is an open system and is designed to not ever become pressurized. The exact method that the drum became pressurized is unclear. The normal lid of the drum was replaced with a lid that has a blower attached that direct the steam through the condenser. Even with the blower lid on the drum there are still openings around the blower unit as is not sealed. In addition, there was a door on the lid that had an opening. The blower did not work when checked after the accident, but it is unknown when it failed. Even if the blower unit failed, the system would not be closed and should not have pressurized. The blower was maintained on a regular preventive maintenance schedule. The drum was new and appeared to be the correct type of drum for the process. There is a possibility that a steam pocket formed under the old sludge in the drum and built up sufficient pressure to rupture the drum. The drum goes through many heating and cooling cycles until the drum is full enough to be sent for disposal. The process is carried out once or twice a week depending on how much wastewater there is to dispose. All six employees were hospitalized for burns.