Two workers of a waste handling contractor lost their lives as a result of the explosion of a vacuum truck where they bad inadvertently mixed sulfuric acid and hydrogen peroxide. The consequences of the explosion were simulated and documented. Root causes and contributing factors were identified and, in particular, failure of the management systems are underlined: (1) inadequate procedures, (2) poor training, and (3) poor management controls. Improved procedures, training, and management controls will prevent accidents of this type. (c) 2005 American Institute of Chemical Engineers Process.