Residents evacuated and at least 11 injured after oil refinery explosion in Wisconsin

Workers describe blast as like a 'big sonic boom'

(KARE 11)

At least 11 people have been injured and many more evacuated after an explosion at an oil refinery in Wisconsin, according to local news reports.

Pillars of dark smoke filled the sky in Superior, Wisconsin on Thursday, after a tank of crude oil or asphalt exploded at the Husky Energy oil refinery. The thick, black plumes drove authorities to evacuate everyone in a three-mile (five-kilometer) radius around the refinery, as well as a 10-mile (16 kilometer) area to the south, according to the Associated Press.

The first fire erupted around 10 am local time, officials said, but was out by 11:20. A second, larger blast went off around noon, driving officials to call for the evacuation.

The blaze was so intense that Superior Fire Department officials were not attempting to extinguish it, the Duluth News Tribune reported. Instead, they pumped water into nearby tanks, hoping to prevent them from exploding as well.

The fire department declared the fire extinguished around 7pm, according to the Superior Police.

Local hospitals reported 11 people were injured – one seriously – but none were killed. All workers at the plant were accounted for, according to the AP.

One contractor at the plant, Eric Mathews, told the West Fargo Pioneer that he was about 200 yards away from the tank when it ignited.

“It was like a big sonic boom and rattled your brain,” Mr Mathews said. “I was running and then the debris started falling out of the air... I stopped under a pipe rack then waited for the debris to stop falling.”

Two miles away, local resident Julia Johnson was working from home when the blast occurred.

"It felt like something had hit the house, like a vehicle or a branch from a tree,” Ms Johnson told the AP. “...Our dogs started barking. It was a stressful moment.”

Ms Johnson and her housemate, Kara Tudor, were among those who were forced to evacuate that afternoon. Superior Mayor Jim Paine said all of the city’s 27,000 residents may eventually have to evacuate, according to the Tribune.

“If in doubt … just leave. Find a place to go,” the mayor said at a news conference.

The University of Wisconsin Superior cancelled classes for Friday, along with two local public school districts.

The refinery has been fined by federal officials once before, under its previous owners, for emergency response and flammable liquids violations. The violations were marked as settled and the problems solved by the end of that year, according to the AP.

The more than 65-year-old plant is Wisconsin’s only remaining oil refinery. It can process around 50,000 barrels per day of crude oil and related products, and store up to 3.6m barrels.