Emergency Evacuation Finally Lifted After Huge Oil Refinery Fire In Superior, Wis.

Safety officials have lifted an evacuation order for miles around an oil refinery in Superior, Wis., after an explosion and a large fire erupted Thursday at the Canadian-owned facility. Police officers went door to door to enforce the evacuation, which extended for miles around the refinery.

"Several people were injured during the incident and taken to hospital," says Husky Energy, which operates the refinery that sits about one mile from Allouez Bay in northwest Wisconsin, near the border with Minnesota. Minnesota Public Radio reports that at least 11 people were injured — one of them seriously.

The evacuation order was finally lifted at 6 a.m. local time on Friday, having remained in effect overnight. Fires reignited several times on Thursday, sending plumes of heavy smoke into the area.

"As black clouds billowed from the refinery, fire crews were involved in a seesaw battle with the fires since the first one broke out at the Husky Energy refinery on Thursday morning," Wisconsin Public Radio reports. "That fire was largely contained, but reignited around noon, prompting Douglas County Emergency Management officials to order evacuations later Thursday afternoon. They continued to expand the evacuation zone as the day went on."

It's not clear what triggered the refinery explosion.

In its most recent update about the zone, the Superior Police Department said the evacuation order covered an area running 12 miles north-south and six miles wide.

Gov. Scott Walker visited the local command center and a shelter. He also inspected the damage from a helicopter, posting a video that showed the charred landscape and lingering fires from the blaze.

The U.S.Chemical Safety and Hazard Investigation Board, a federal agency that investigates serious chemical incidents, has sent a four-person team to the site.

In a preliminary notice, the agency said the Husky Energy refinery had been shutting down in preparation for "a five-week turnaround" — a break in operations for maintenance and inspection — when the explosion occurred around 10 a.m. local time. That triggered one fire; a larger one erupted shortly after noon.

The initial explosion seems to have hit "a tower near giant asphalt storage tanks," the Duluth News Tribune reports, adding, "One of those tanks was punctured, spewing liquid asphalt onto the ground for hours."

Much of the heavy smoke reportedly came from burning asphalt. The News Tribune says firefighters at the scene had to wait for hours to be sure "a potentially dangerous toxic chemical, hydrogen fluoride, was not at risk of exploding."

Describing the fire that lingered, the Twin Cities Pioneer Press reports, "Thursday evening a new fire ignited from a liquid [Superior Fire Battalion Chief Scott Gordon] described as a 'heavy material very similar to a bunker fuel that is not quite as heavy as asphalt but still very heavy,' which was pouring out of a valve that could not be shut off."

As for the evacuation's effect on people who live in the area, Minnesota Public Radio reports:

"The blaze shut down three schools and a hospital and sent concern through this harbor community of 27,000 residents. Schools in Superior and nearby Maple, Wis., canceled classes Friday as a precaution.

"Evacuees were sent to the Duluth Entertainment Convention Center, where cots and food were provided. It was unclear how many residents and others were impacted."

The Superior facility is the only oil refinery in Wisconsin, employing some 180 workers, Husky Energy says. The refinery has capacity to store 3.6 million barrels of crude and other products, and it has operated for decades under a string of owners; Husky Energy bought it last year for $435 million.

The refinery processes "both heavy crude from the Canadian tar sands in Alberta and lighter North Dakota Bakken crude" into fuel and asphalt, according to Minnesota Public Radio. The facility is linked into the Magellan pipeline system, which runs through the central U.S. down to the Gulf Coast.

After reviewing safety records, MPR reports that the refinery has paid several penalties to federal regulators, including $31,937 in Clean Air Act penalties over the past five years.

And in 2015, the Occupational Safety and Health Administration levied a $21,000 fine for "violations related to hazardous waste operations, emergency response and flammable and combustible liquids," the station says. Similar issues were mentioned in a 2007 action against the refinery's former owners back in 2007, when they were hit with a $179,100 fine.

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