Abstract: Employees #1 through #4 inserted a inflatable air plug rated for 35 psi into a suction pipe on a sewage station pump intake line in an attempt to find a vacuum leak. The plugs were inflated at a depth of approximately 10 feet into the vertical pipe, where the blue print showed a 16 inch pipe diameter. After approximately 10 minutes of inflation, a loud noise was heard and parts of the pipe plug ejected, striking Employees #1 through #3, who were standing over and beside the pipe end and Employee #4, who was across the room. Employee #1 sustained massive head trauma and Employee #2 sustained trauma to the head, loss of one eye and trauma to his hand. Employee #3 sustained head trauma and Employee #4, who was across the room, sustained a minor scalp laceration. Employees #1 through #3 were hospitalized for their injuries. The air compressor used was set at an automatic cut off pressure of approximately 122 psi. No training had been provided to the employees in the testing, inspection and use of the plugs.