SUPERIOR, Wis. — A federal agency says a massive refinery fire that forced the temporary evacuation of homes in the coastal Wisconsin city of Superior in April was caused by an explosion that sent debris hurtling into an asphalt storage tank.
According to the report, the explosion sent a piece of debris about 200 feet (61 meters) into an aboveground storage tank of asphalt. The tank was punctured and spilled hot asphalt, which ignited about two hours later.
The report says 36 people sought medical attention after the explosion, including 11 refinery and contract workers. A large part of Superior was evacuated.