The Occupational Health and Safety Administration, or OSHA, has fined a Superior refining company $83,150 for worker safety violations after a series fires and an explosion at a refinery in April. The agency cited the refinery for eight serious violations of safety management procedures.

OSHA fined Superior Refining Company, which is owned and operated by Canadian firm Husky Energy. It was at Husky Energy's refinery in Superior where fires and an explosion April 26 caused the evacuation of residents from Superior and led 36 people to seek medical care. No one was killed.

OSHA found the refinery failed to inspect and test equipment to ensure it was fit for service. In addition, the agency said the company did not adequately address hazards associated with shutdowns — the company was preparing to shut down the refinery for five weeks as part of maintenance and repairs.

Workers and contractors were also not properly trained on equipment involved in the shutdown, according to OSHA.

Also, the refinery could not demonstrate a process was in place to show the right materials and parts were being used to repair and replace equipment. OSHA says the company also failed to take steps in the interim to mitigate risks and address potential hazards that included the failure of a slide valve used at the time of the explosion April 26.

The U.S. Chemical Safety Board said in August that a worn valve in the fluid catalytic cracking unit at the refinery appeared to allow a flammable mixture to form, which likely caused the explosion. The valve, called a slide valve, serves to separate parts of the unit to prevent a flammable mixture from forming.

"Ensuring the mechanical integrity of critical equipment used during the refinery shutdown operation could have prevented this incident," said OSHA Eau Claire Area Office Director Mark Hysell in a release. "Superior Refining Company LLC has been working cooperatively with OSHA to ensure a comprehensive process safety management program is implemented at the facility before resuming production."

Superior Refining Company has 15 days to contest the fine or request an informal conference with OSHA.

A spokesman for Husky Energy said the company looks forward to meeting with OSHA to discuss its findings and recommendations.

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"It is our policy to continuously improve our process safety programs. Superior Refining remains committed to this facility, our employees and the community," said Mel Duvall, Husky spokesman, in an email.

Ginger Juel, co-founder of the Twin Ports Action Alliance, said the fine is a slap on the wrist.

"This wasn’t the first time this company, the Superior Refining Company, has been cited for some of the serious issues by OSHA," she said. "If Husky really wants to be a good neighbor to our community, they’ll make a commitment to not continue operations like this."

Juel said the agency's findings were further evidence of why the refinery should commit to removing hydrogen flouride as part of its refining process. The highly toxic chemical prompted an evacuation order for much of Superior.

An investigation by the U.S. Chemical Safety Board (CSB) is ongoing.

In August, the board said inspection and maintenance of the slide valve by the refinery would be examined by the CSB. The board has also said it will hold a public hearing in Superior or Duluth this fall about the agency’s investigation after a request from five congressional lawmakers. The date and location of that meeting is yet to be determined.

OSHA regulators have previously cited the refinery for more than 30 safety violations under previous owner Murphy Oil, according to a 2011 report by the Wisconsin Center for Investigative Journalism.

Editor's note: This story was last updated at 3:38 p.m. Tuesday, Oct. 2, 2018, with comments from Ginger Juel, co-founder of the Twin Ports Action Alliance.