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US refinery officials knew about issues years before 2018 explosion injured 36 people and caused mass evacuation

10 May 2022

Documents obtained from the US Occupational Safety and Health Administration (OSHA) have revealed that officials were aware of equipment issues at an oil refinery in Superior, northwestern Wisconsin years before a 2018 explosion injured 36 people and caused the mass evacuation of 21,000 people.

The blast caused a large plume of black smoke - Image: Shutterstock
The blast caused a large plume of black smoke - Image: Shutterstock

Around 1,300 documents, which were obtained by Wisconsin Public Radio, have revealed exactly what officials at the Superior refinery, then owned by Husky Energy Inc., were aware of. Among the issues that officials knew about were problems related to critical valve malfunctioning just a few days before the April 2018 blast, as well as erosion which had occurred on equipment and left untreated since 2008.

The explosion on 26 April 2018 occurred while the refinery was shutting down in preparation for a five-week turnaround. The blast was likely caused by a faulty valve. An investigation by the US Chemical Safety Board (CSB) found that the blast was likely caused by internal wear on a faulty valve.

According to the documents obtained by Wisconsin Public Radio, refinery officials had been aware of the erosion for almost a decade as a result of previous inspections and that it could leak. In addition, in the week before the 2018 explosion, workers at the plant had noted in operator logs that the valve was malfunctioning and had caused the shutdown of the refinery’s pollution control device.

Husky Energy reached a settlement of around $1 million in July 2021 to be spread between those impacted by the incident. The settlement was reached in a federal lawsuit that was brought forward by three local residents who claimed they had suffered economic losses and other damages as a result of the incident and evacuation. As part of the settlement, the Superior Refining Company – which was owned by Husky Energy at the time and now owned Cenovus Energy – did not admit any wrongdoing.

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