Defective welds likely caused the collapse of a tank last month, spilling about 2 million gallons of liquid fertilizer and injuring four people.
That’s the preliminary conclusion of the U.S. Chemical Safety Board (CSB), which will now conduct a full, detailed investigation into the Nov. 12 incident at Allied Terminals in Chesapeake, VA.
The welding was performed in 2006 to strengthen four fertilizer tanks that were built around 1929.
CSB’s lead investigator said the agency found incomplete penetration of the welding metal into joints. The welding defects likely weakened the tank and led to its failure when liquid inside was raised to just three inches below its recommended safe fill height.
The investigation also determined that the three other large fertilizer tanks likely have similar welding defects. One of the tanks is just 250 feet from homes.
CSB recommends Allied conduct an independent engineering analysis for the remaining tanks.
John Bresland, CSB chairman, said, “it appears that no federal, state, or local agency has clear regulatory and enforcement responsibility for the safety of non-petroleum aboveground storage tanks.”
Part of CSB’s ongoing investigation will be to determine whether additional safeguards are necessary at national and state levels.
The tank collapse seriously injured two contract workers, who were hospitalized. Two members of the public who tried to help the injured men required treatment, likely related to exposure to ammonia vapor.
The fertilizer overtopped a containment dike and flooded sections of a nearby residential neighborhood.