Contained within the 87 page WorkSafe BC final report on the Jan. 20, 2012 Babine Forest Products (BFP) mill explosion that killed two workers and injured many more are details regarding the exact cause – as best as can be determined by investigators – of the terrible accident.
Available oxygen, confined space, dry wood-dust accumulation, and what was probably an open flame, combined to produce the massive explosion that night.
Other gases present in the environment, thanks to safety-valve venting of pressurized combustible gas containers also contributed to the force of the explosion.
WorkSafe BC investigators determined the source of the ignition to be a flame ignited by friction generated within a motor assembly.
The motor assembly, located in the facilities half-basement below a waste conveyor system, had become packed with accumulated dust to the point where, the report said, the moving parts within the motor were in constant contact with the accumulated dust.
This constant moving contact was enough to start the debris in the assembly to smoulder. The limited space within the assembly would have prevented ignition to a flame within the assembly, but it is suggested that smouldering debris would have been transported closer to the exterior of the assembly where sufficient oxygen was present to create an open flame.
Just prior to the explosion, the report said, fire alarms where triggered within the mill. They were not loud enough for workers to hear them over noisy machinery, but a watchman was in the process of investigating the alarms when the explosion occurred.
High levels of airborne dust and accumulated dust were determined to be the primary source of the conflagration. Contributing factors were low winter humidity, closed windows due to cold temperatures, and the presence of pine resin, the result of a pine beetle killed tree’s natural response to the invading insect.
Sprinkler systems installed to mist airborne dust were not fully operational thanks to the extremely cold weather in the weeks leading up to the explosion. Many were frozen.
The report did indicate that older mills throughout the province, including BFP, were not built to take into account the dust levels associated with processing large volumes of dead pine.
Dust collection systems were, according to the report, absent from some of the dustiest areas of the mill. Small fires within the mill were previously noted, but WorkSafe BC did not follow up on those fires beyond requesting BFP to file their own reports regarding the incidents.
Although wood dust collection and removal systems were found to be inadequate to the task, the report also said that BFP had been taking steps to improve dust control within the facility.
“The Babine sawmill was spending considerable amounts of money on upgrading the sawmill’s production capabilities and improving the dust management system by opening up floors, pressurizing the [motor control centre panels], and improving the waste conveyors systems,” the report said.
At the time of the explosion, BFP was under a December 2011 order to improve airborne dust removal systems.
“However, no adequate actions were taken to reduce or control the levels of airborne wood dust within the mill,” the report said.
The report noted that BFP had significant dust removal upgrades in the works, including a down payment on additional or replacement dust removal systems, as well as one of two additional exhaust fans already on site to be installed.
The installation of those systems were delayed because of required upgrades to the electrical systems before they could be installed. The required electrical upgrades were, according to WorkSafe BC, already underway when the explosion occurred.
The final conclusion of the report, which has received the most media attention, was that the accident was preventable.
WorkSafe BC did not issue a stop work order against BFP, despite having itself noted that dust accumulation levels were above acceptable standards.
The responsibility for worker safety, the report concluded, ultimately lay with the employer.
At press time, BFP had not issued a response to the WorkSafe BC report. Steve Zika, BFP chief executive officer, said they were waiting until after the passing of the two-year memorial last Monday to issue their statement out of respect for the families involved.
Zika did say that BFP disagrees with the conclusions of the WorkSafe BC report.