Updated as of December 12, 2018:

On April 26, 2018, an explosion and subsequent fire occurred in the refinery's fluid catalytic cracking unit (FCCU) at the Superior Refinery Company LLC refinery in Superior, Wis. As a result of the explosion, 36 people sought medical attention, including 11 refinery and contract workers who suffered OSHA-recordable injuries. In addition, a portion of the town was evacuated.

According to an interim report issued by the U.S. Chemical Safety Board, evidence collected suggests similarities with a previous investigation of the February 18, 2015, explosion at a refinery in Torrance, Calif.

Download the CSB's interim report on the Superior explosion and fire here.


Original story:

A four-person investigative team from the CSB is investigating the scene of the April 26 explosion at the Husky Energy oil refinery in Superior, Wis.

The refinery was shutting down in preparation for a five-week maintenance turnaround when the incident occurred. Several workers sought medical attention, and thousands of residents near the refinery were asked to evacuate due to heavy smoke.

The investigative team is conducting interviews and reviewing evidence. The on-site phase of the investigation, which is expected to take several weeks, will focus on:

  • Documenting and collecting physical evidence.
  • Photographing the refinery and the incident scene.
  • Interviewing Husky employees and contract employees involved in activities potentially pertaining to the incident.
  • Obtaining documents related to the tasks being performed at the refinery around the time of the incident, including work plans, site safety plans, hazard analyses and job safety analyses.
  • Obtaining construction, maintenance and inspection records of equipment suspected to be involved in the incident.
  • Reviewing the effectiveness of emergency response to the incident including evacuation efforts.