MINNEAPOLIS (WCCO) — A hole in a valve is likely the source of an explosion at the Husky Energy Refinery in Superior, Wisconsin last spring.

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The explosion injured 36 people and led to the evacuation of a large part of the city.

(credit: CBS)

The United States Chemical Safety and Hazard Board shared its findings Wednesday during a Town Hall meeting.

They say erosion created a hole in the slide valve, allowing air to mix with chemicals, which caused the explosion.

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