The company that runs the Co-op refinery in Regina has pleaded guilty to an occupational health and safety charge stemming from a 2011 fire and explosion.

On Thursday, Consumers’ Co-operative Refineries Ltd. entered a guilty plea to one count of failing to ensure all work was sufficiently and competently supervised, in contravention of provincial occupational health and safety regulations.

The Crown has agreed to withdraw four other counts against the company. A sentencing hearing is scheduled for May 12.

In October 2011, a corroded pipe ruptured at the refinery, causing a fire and explosion that injured 52 people, 13 of whom needed immediate medical attention.

The injured workers have since filed a lawsuit alleging negligence put workers at risk. A statement of claim says there were known safety concerns before the explosion, including possible gas leaks, lack of alarms and an inadequate emergency medical plan.

None of the allegations have been proven in court.