Investigators searched for the cause of the massive Thursday morning explosion at the refinery, capable of processing up to 38,000 barrels of oil a day, which shook the city of Superior, Wisconsin, home to about 27,000 people. Tens of thousands of people in the city of Superior were urged to leave their homes.
A large fireball erupts during a series of fires and explosions at the Husky Energy refinery in Superior, Wis. Thursday, April 26, 2018.
Authorities say they believe there's no further danger to the public following an oil refinery explosion in northwestern Wisconsin that injured at least 11 people and sent billowing plumes of black smoke into the air.
Paine said he lifted the evacuation order at 6 a.m., only after receiving the all-clear from the U.S. Environmental Protection Agency and the DNR that conditions were safe for people to return.
Mattson and others said they heard from people who went to Poplar, about 17 miles southeast of the refinery, who said the air smelled like chemicals. He said one Husky employee and one contractor had remained in the hospital overnight, but were likely going to be released today. All of the refinery's workers were accounted for, Husky said. Since the fire was put out, data shows that there are no elevated levels of chemicals monitored and that particulate levels are at background levels.
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As a precautionary measure, local officials ordered all residents within a three-mile radius around the refinery to evacuate.
Calgary-Alberta-based Husky Energy refinery bought the refinery from Indianapolis-based Calumet Specialty Products Partners past year for over $490 million. She said the extent of injuries is unknown.
The Wisconsin Department of Natural Resources and EPA are also doing water and air monitoring. It produces asphalt, gasoline, diesel and heavy fuel oils, largely using heavy crude oil imported from Canada.
Husky had purchased the 38,000 barrel per day refinery from Calumet Specialty Products Partners LP previous year.
In 2015, when Calumet was owner, OSHA issued four citations to the refinery, three of them for serious violations involving flammable and combustible liquids, hazardous waste operations and emergency response.