The NTSB has also advised the National Tank Truck Carriers and Chemical Manufacturers Assn. that the Manual of Operating Recommendations should be revised to include recommended practices aimed at preventing the unloading of hazardous materials into the wrong storage tank.
The advisory stems from a 1998 incident at Ford’s Kentucky Truck Plant in Louisville, when a liquid mixture of nickel nitrate and phosphoric acid was accidentally unloaded into a tank containing sodium nitrite solution. An employee at the plant inadvertently attached the cargo transfer hose to the wrong tank. When the nickel nitrate and phosphoric acid solution from the truck mixed with the sodium nitrite solution in the storage tank, the chemical reaction produced toxic gases of nitric oxide and nitrogen dioxide.
The driver of the truck stopped the transfer when he saw an orange cloud coming from the bulk storage building, but about 2,400 people had to be evacuated from the plant and surrounding businesses and another 600 local residents were told to remain inside their homes. Three police officers, three plant employees, and the truck driver were treated for minor inhalation injuries. Damages exceeded $192,000.
NTSB determined that the probable cause of the accident was inadequate training of plant employees regarding procedures for unloading bulk hazardous materials and similar labeling of adjacent pipe connections. It recommended that Ford distribute written safety-critical procedures to all employees engaged in cargo transfer operations.
In letters to the National Tank Truck Carriers and the Chemical Manufacturers Assn., NTSB recommended that unloading and loading standards be adopted such as a requirement that drivers personally verify or question all transfer connections before beginning delivery of the product.
The agency also criticized the U.S. Department of Transportation for not having adequate safety requirements for unloading hazardous materials from highway cargo tanks. The DOT's Research and Special Programs Administration is currently evaluating a broad rulemaking, initiated in 1996, that would include new rules concerning loading and unloading operations.