A method and apparatus for controlling a valve during the detection of a hazard event. A hazard event is defined as an event that may endanger the health or safety of people or the environment from contamination of hazardous material carried by a vehicle. The hazard event may be detected from a condition of the vehicle, an input received from a vehicle operator, or a message received from a remote location. After detecting a hazard event, a valve located on the vehicle is controlled to prevent contamination from the hazardous material being transported.