Superior, Wis. evacuees head home, authorities continue to investigate cause of refinery explosion

SUPERIOR, Wis. (KMSP) - City officials lifted the mandatory evacuation order affecting thousands of Superior residents early Friday morning, after the last of the fires at the Husky Energy Refinery were put out late Thursday night.

Concerns a tank containing the toxic chemical hydrogen fluoride would rupture prompted the evacuation, but those fears turned out to be unfounded.

“The team that really managed this crisis had prepared for this for a long time,” said Superior Mayor Jim Paine. “When this crisis happened, they kept a cool head; they acted with sound judgment and in many cases downright courage.”

Since the fire began, the Environmental Protection Agency (EPA) has been monitoring the air to make sure it’s safe to breathe. They set up seven air quality monitoring stations around the city to measure volatile chemicals, particles and dust found in smoke, but officials say the levels are lower than normal meaning the air is safe to breathe.

“This is important because it gives us the indicators of the nature and extent of the materials leaving the refinery and the potential impacts it could have on human health,” said Jim Mitchell, EPA on-scene coordinator.

Fire officials said that at one point, the heat from the burning asphalt was so intense that firefighters’ boots were melting as they approached the flames.

“This product is sort of like lava that kind of has a flow to it,” said Superior Fire Department Chief Steve Panger. “It’s so hot when it burns off you can’t put foam on it. You have to wait until it cools off so you can start the water foam operations. We don’t have a heat gun on it but it is burning at several thousand degrees at its height.”

City officials are no closer to figuring out what caused the initial explosions that resulted in the asphalt fire that burned for much of the day Thursday, but they believe the danger to the public has passed.

More than 27,000 people evacuated from the area surrounding the refinery. Many returned to their homes Friday.