Abstract: Employee #1, a sales representative for a hazardous waste disposal company, was attempting to take a sample from an overpak drum. The 85 gallon overpak drum contained a 55 gallon drum that had been inserted upside down when it was discovered to be leaking. This drum handling had been performed by the generator of the hazardous waste that was to be sampled for a chemical profile. Employee #1 was not cautious when he loosened the bung or ring to release excess internal pressure from the drum. He had vigorously cranked the 5/8 in. bolt about five turns when the open head top of the 85 gallon drum explosively released its pressure and the top flipped up into his face. Employee #1 sustained a concussion, facial fractures, and facial lacerations.