Welding work on fuel truck to blame for explosion north of Montreal that killed 3

An explosion that killed three people at a fuel distribution business north of Montreal occurred when flammable vapours inside a tanker truck ignited while a welder worked on it, investigators said Tuesday.

The explosion at Propane Lafortune, a family-run outlet that sold propane and other fuels in Saint-Roch-de-L'Achigan, Que., on Jan. 12, 2023, sparked a blaze that forced the evacuation of nearby homes, drew firefighters from across the region and took hours to extinguish.

"There were preventive measures that could have been taken," Richard Fontaine, the director of prevention and inspection for the North Shore branch of Quebec's workplace safety board, the CNESST, said at a news conference.

"There are things that could have been done that weren't that day."

Chief among those was that the tanker truck being repaired that day had not been properly cleaned of any remaining fuel. That meantleftover gasoline and diesel fuel remained in the truck's reservoir whilea welder worked on it.

The truck was also being repaired indoors, in a small garage connected to Propane Lafortune's main office building a confined space where the fuel vapours were concentrated, investigators said.

The welder, Christophe Paradis, was one of the three people killed by the explosion the other two,Cline Pilon and France Desrosiers, were working in the adjacent offices. Paradiswas a subcontractor, hired by Propane Lafortune to repair the chassis of the tanker truck.

The truck was in bad shape, Mylne Lauzire-Svigny, the CNESST's director of prevention and inspection for the Lanaudire region, said.

A few days before the explosion, inspectors with Quebec's automobile insurance boardhad noted that the truck's steel chassis was cracked in multiple places and needed to be repaired before it could continue delivering fuel.

But the truck had performed one final delivery of gasoline and diesel just days before repair work began. During that delivery, the truck had been emptied of fuel, but not steam-cleaned and there was probably still a significant amount of gasoline left in the reservoir that hadn't properly drained, according to investigators.

It was that remaining fuel, in vapour form, that ignited while the welder was installing reinforcing steel plates onto the bottom of the chassis.

It was unclear, the investigators said, whether it was the heat of the welder's tools, intended to be used for steel, that somehow melted a hole in the aluminum fuel reservoir, or if the presence of an electrical current from those tools somehow created a spark, or even if some other mechanism ignited the fuel vapour.

But welding work done indoors on a tanker truck that had not been properly steam-cleaned of remaining fuel is an inherently risky undertaking, Fontaine said, and breaksa slew of fire prevention guidelines.

The CNESST investigation was a first step in determining the cause of the explosion, but it attributed no wrongdoing.

The workplace safety board could later fine Propane Lafortune anywhere between $1,936 and over $300,000.

"This report now provides answers to the final question that has remained unanswered since the tragedy: how did this happen?" Sbastien Marcil, the mayor of Saint-Roch-de-l'Achigan, said in a statement.

"On behalf of the three victims who lost their lives in tragic circumstances, their families and our community, we must now hope that the report's conclusions can prevent such events from recurring in the future in these workplaces."

Fontaine said the CNESST report would be shared with Quebec's Education Ministry to help train future welders to prevent this kind of accident from reoccurring.