Federal investigators identify cause of Superior refinery explosion

December 12, 2018 10:25 PM

A federal investigator said Wednesday that the explosion at the Husky Energy oil refinery in Superior, Wisconsin last April was caused by a faulty safety valve and launched debris 200 feet - puncturing a storage tank filled with asphalt that led to additional fires.

The Chemical Safety Board also confirmed that a significantly more toxic chemical called hydrogen fluoride was stored roughly the same distance from where the explosion occurred. While those tanks were not impacted by the explosion, new details about the proximity of the blast reignited fears that it could have led to a chemical leak.


RELATED: Superior refinery explosion occurred during crude oil heating, extraction process

"Last April, we were very lucky," said Susan Hedman, an attorney for a Wisconsin environmental advocacy organization.

Rick Engler, a CSB board member, said investigators must now figure out if HF, which has been used by refineries since the 1950s to improve the quality of gasoline, was stored at a safe distance.

"I think it would be valuable to look at whether debris…. under slightly different circumstances could have hit vessels or piping involving HF," Engler said.

"It's a widespread concern in the industry . . . are the guidelines stringent enough? That's one question I hope we'll be looking into as this ongoing investigation continues," he added.

5 EYEWITNESS INVESTIGATION: Who is checking safety plans for toxic chemical stored at oil refineries?

It's a question that could have been answered prior to the explosion. But a 5 EYEWITNESS NEWS investigation this past fall found the Environmental Protection Agency, which regulates all refineries that use HF, had never inspected the Husky Refinery.

That investigation triggered even more concerns among safety advocates and neighbors.

Hedman asked the company to stop, or at least phase out, use of the chemical.

RELATED: In wake of explosion and fire, Duluth Mayor calls for change to oil refining process

In a statement, a spokesperson for Husky Energy said the company realizes "the community still has questions and concerns about what happened…we continue to evaluate options around the use of hydrogen fluoride. "

However, Ron Chittin with the American Petroleum Institute said witching to another manufacturing chemical is not as simple as it may seem.

"No refinery in the US has ever converted…you essentially have to tear down, get rid of the old one and build a new one," he said, adding that the risks of HF can be managed.

RELATED: Superior refinery explosion caused $27M in damage, $53M in expenses; 2020 restart

Husky is currently working on designing a new plant. The refinery will not be back in operation until 2020, according to the spokesperson.


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Joe Augustine

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