Regina fire investigators are still waiting for the go-ahead from Federated Co-op refinery engineers to start examining what caused an explosion at the plant Christmas Eve.
The boom was heard and felt across the city around 3 p.m. Tuesday.
Co-op officials said the explosion happened in a large tank in a propane-butane processing unit.
An on-scene fire suppression unit contained the fire.
Co-op officials said they’re taking the incident very seriously.
“We’ve got a lot of processes in place, as any refinery should, but one [incident] is too many, and we’ve had a few,” said Dan McMurtry, the refinery’s vice-president of systems strategy.
The explosion was the fourth major fire at the refinery in the last two years.
In February, a fire in a coker unit sent flames shooting nearly 20 metres in the air, but was quickly brought under control.
In October 2011, corrosion in a pipe triggered a fireball that sent seven contract workers to hospital and forced 1,400 workers from the facility.
In May 2012, a much smaller fire occurred when an overheated crude oil pump ignited. There were no injuries.
