Smoke rises from the Babine Forest Products mill in Burns Lake, B.C. Sunday, Jan. 22, 2012.Jonathan Hayward/The Canadian Press
WorkSafeBC has called on a U.S. expert to establish a measuring stick for the explosive risk of sawdust, a first step in what could lead to regulations for dust levels at mills across the province.
In its first update on its investigation into the Burns Lake sawmill explosion and fire that in January killed two people and injured 19, WorkSafeBC cautioned that sawdust is just one of the potential fuel sources being investigated. Natural gas and propane remain possibilities.
However, WorkSafeBC said a U.S. laboratory has been retained to examine samples from the mill for particle size and the minimum explosive concentration required for sawdust to fuel an explosion.
Roberta Ellis, a senior executive with the workers' compensation board, said the Burns Lake investigation will determine what regulations, if any, are put in place.
"Whatever comes out of that, the result of this investigation, will be used to illuminate what sorts of standards, if any," Ms. Ellis told reporters during a conference call on Wednesday. "…If this is identified as being critical information and it may very well be … that would give us the information to look at what has happened here and what should we do differently."
WorkSafeBC's update on the Babine Forest Products mill explosion came a week-and-a-half after an explosion at a Lakeland Mills Ltd. sawmill in Prince George, in which 24 people were sent to hospital, two of whom died.
Last week, WorkSafeBC said releasing preliminary findings on Burns Lake could compromise its process. It later shifted gears and said it would reveal what factors it had ruled out.
Workers, industry experts and the news media have for months pointed to the cutting of wood harvested from forests ravaged by the mountain pine beetle as a possible explanation. The wood produces a fine, dry sawdust that is more likely to explode when airborne than the normal, wetter timber.
Ms. Ellis repeatedly noted that sawdust has not been proven to be the fuel source. She said a natural gas pipe and valve have been seized for testing, as have two propane tanks.
Like the fuel source, the ignition source remains unclear. Investigators have ruled out arson and lightning strikes (some Burns Lake residents had raised that as a possibility). WorkSafeBC said it continues to examine ignition sources such as hot surfaces and electrical components.
WorkSafeBC said possible factors in the explosion include the type of wood being milled, the exhaust and ventilation systems and the cold weather.
WorkSafeBC monitors workplace dust levels in relation to respiratory problems, but Ms. Ellis said this is the first time she's aware of that dust samples have been sent to labs for combustibility testing.
Ms. Ellis said the Babine mill explosion has been among the largest investigations in her organization's history. Up to 20 staff have worked on the case and conducted more than 80 interviews. The investigation is expected to take another two to three months.
After the Prince George explosion, WorkSafeBC ordered all sawmills in the province to review the build-up of sawdust at their operations.
Bob Matters, wood council chair for the United Steelworkers, said the union would support dust regulations.
"If that's found to be a problematic combustible and certain thresholds should be met, then I would certainly expect there would be immediate regulations written to address those issues," he said.
Ms. Ellis said Wednesday's update was an unusual step for her organization. But Peter Lineen, chief executive officer of the B.C. Forest Safety Council, said he'd like to see the agency do such things more frequently.
"As information does become available, I have the sense that WorkSafeBC is going to table that as soon as they have it," he said. "For an industry that has a history of having some pretty serious incidents, you can't afford not to be surrendering that information as quickly as possible so people can learn from it."
The Globe and Mail reported earlier this week that in the aftermath of the Burns Lake explosion, WorkSafeBC conducted inspections at 70 mills. The Prince George mill that went up in flames last week was not among them, its owner said.
However, the company said it requested an inspection in February after a $21-million capital investment. A WorkSafeBC inspector flagged the "accumulations of piles of wood dust" but did not issue a corrective order. Sinclar Group Forest Products Ltd., which owns Lakeland, said it cleaned away debris and increased its clean-up crew to five workers from three.
WorkSafeBC said on Wednesday it could not say which mills were among the 70. It said the inspections led to 90 violation orders, but wouldn't disclose the reasons for the violations.