SUPERIOR, Wis. (AP) — A hole in a valve was cited as the source of an explosion at a Husky Energy refinery in northwestern Wisconsin last spring that injured 36 people and required the evacuation of a large part of the city of Superior.
The latest findings of the U.S. Chemical Safety and Hazard Investigation Board were shared Wednesday at a town hall meeting in Superior.
According to the update , erosion created a hole in the slide valve, allowing air to mix with hydrocarbons. The resulting blast sent debris hurtling into an asphalt storage tank. The puncture spilled about 15,000 gallons (12,490 imperial gallons) of hot asphalt, which later ignited.
A spokesman for Husky Energy says the Canada-based company will continue working with the board to understand the cause of the explosion.