The Burns Lake sawmill leveled by a massive fiery blast on Jan. 20 was the site of a sawdust-fuelled explosion nearly a year earlier, but WorkSafe BC officials did not test for explosive risk during a November inspection that found unhealthy concentrations of airborne sawdust.
WorkSafe BC officials say they were aware of a report from the B.C. Safety Authority that was released on Tuesday containing the details of the February, 2011, incident at the Babine Forest Products mill. The report said the buildup of unusually dry sawdust in and on equipment fed a small dust explosion, which in turn set sawdust on the floor ablaze. The explosion was triggered by a faulty switch for a band saw motor.
But the agency responsible for worker safety believed that the other regulator had taken corrective steps. The safety authority, which has responsibility for industrial systems including rail, electrical and gas, approved the repair of electrical systems. Officials from both agencies confirmed that they did not directly address the explosive risk of airborne sawdust particles.
"We were satisfied the electrical equipment was clean and restored to top condition," Stephen Hinde of the B.C. Safety Authority said on Tuesday. "We don't regulate the sawdust itself."
A probe is under way into the Jan. 20 blast that killed two workers and injured another 19. The level of dry sawdust at the mill is just one possible cause that is being investigated.
The wood being processed by sawmills in the B.C. interior, including Babine Forest Products, has fundamentally changed in recent years as the forest industry races to process tinder-dry logs killed by the mountain pine beetle.
WorkSafe BC was just starting to consider that new reality in recent months, said Al Johnson, the agency's sawmill safety expert. It sent inspectors to the mill in November as part of a broad study to determine if the drier wood and faster sawing technology had rendered workplace safety regulations ineffective.
Under the present regulations, B.C. companies are required to remove accumulations of combustible dust in a building or structure, or on machinery or equipment, before it can cause a fire or explosion.
But the regulations are not specific. "That's performance-based regulation, it's not prescriptive, it doesn't tell you if you have a centimetre of dust on a beam you have to remove that dust, it says the employer has to ensure that dust doesn't accumulate so that an explosion or a fire doesn't occur," Mr. Johnson said. "It's somewhat subjective."
Mr. Johnson said the regulatory review is still under way. "With drier wood and faster saws, often you'll create a finer wood dust," he said. "As technology changes, we try to ensure the regulations keep up to that."
He cautioned against connecting the sawdust concerns with the devastating explosion on Jan. 20, saying it is still too early to conclude what happened. "If something comes out of the investigation that lends itself to a change in practise, that's what the investigation is for," he said. "From our perspective in prevention, we're there to learn from this and ensure it doesn't happen again."
John Allan, president of the Council of Forest Industries, said the makeup of the wood going through the province's interior mills has changed dramatically in the past few years. An estimated 64 per cent of the pine harvest in B.C. in 2010 was dead wood.
He said mill owners have invested millions of dollars adapting to the new mix of wood: "It is a manufacturing challenge. These logs, they are dry, cracked, brittle, they explode. Logic would say the dust level would be higher than otherwise."
However, he stressed that safety measures in the mills are top-notch. The B.C. Forest Safety Council was formed to address workplace safety in the woods due to high numbers of deaths and injuries, but it has not been broadened to look at mills because they are generally safer.
That could change after the tragedy at the Babine mill, Mr. Allan said, but added: "I think we should wait to see the results of the investigation are before deciding that."