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WorkSafe investigator walks inquest through Babine blast

High accumulations of wood dust were a constant theme when the coroner's inquest into the explosion that leveled Babine Forest Products and killed two workers was taken Tuesday through the sequence of events a WorkSafeBC investigation concluded led t
Paul Orr
WorksafeBC investigator Paul Orr heads into the coroner's inquest in Burns Lake on Monday.

High accumulations of wood dust were a constant theme when the coroner's inquest into the explosion that leveled Babine Forest Products and killed two workers was taken Tuesday through the sequence of events a WorkSafeBC investigation concluded led to the fatal blast.

Robert Luggi, 45, and Carl Charlie 42, were killed in the Jan. 20, 2012 incident that also injured 19 others as it destroyed the sawmill located on the outskirts of the community of 2,000 residents about 225 kilometres west of Prince George.

Paul Orr, WorkSafeBC's lead investigator into the blast, said the point of origin was a V-belt assembly connecting a motor to a gear reducer, in turn connected to a conveyor, in the basement below the eliminator table, where roughly-cut lumber is rejected or put through for further processing, on the mill's east side.

He said the assembly was covered by a guard and enough sawdust had migrated and compacted inside the guard to create friction with the belt and ignite a smouldering fire that erupted into a short flash fire once it had drawn enough air.

The assembly was located near a transfer point for two conveyors where an overflow of sawdust had built up and there was enough sawdust in the air for the flame to ignite a "deflagration" or explosion that travels just below the speed of sound.

It can produce temperatures in the range of 3,000 C, about three times as hot as a candle flame, "so the metal around you is going to be very hot," Orr said. Characterized by a loud whooshing sound, a deflagration also produces a tremendous amount of pressure.

It was such a pressure wave, followed in "milliseconds" by a flame front, that ripped through the building, progressing from east to west and mostly along its northern wall in what Orr described as a "continual explosion" rather than a series of blasts.

As it did, it lifted the floor on the operating level above before expanding and blowing up.

The north and east walls and the sawmill's roof were blown out before the blast ran out of fuel but the metal remained hot enough to start fires throughout the sawmill, some of which continued to burn days after the explosion.

Orr said Charlie was working in a shack located outside the mill's north side where he cut logs to length for processing inside the facility. Investigators believe Charlie's shack collapsed with the force of the blast and Orr noted that of the four shacks housing cutoff saw operators along the mill's north side, only Charlie's had not been improved with metal walls.

As for Luggi, his body was found on the operating level near the sawmill's northeast corner.

Orr said co-workers last saw him on the operating level going downstairs near where the blast originated to check on something moments before the explosion.

Orr noted that the two men who died from the severe burns they suffered in the Lakeland Mills explosion in Prince George three months later made it out of the mill before they were taken to hospital, and said it appeared something similar happened to Luggi.

"It's our belief or our theory that Mr. Luggi had gone into the basement and was caught in the middle of the fireball," Orr said.

"He managed to make it up to that (operating) level to try and get himself out of the mill and he succumbed there or the roof came down or something else prevented him from exiting the mill."

Orr said the mill's configuration created a "natural funnel" that allowed the explosion to reach the operating floor where there were several workers.

"(It's) only by a miracle that we did not have quite a number more fatalities," Orr said.

There were 33 workers inside the sawmill at the time, with about a half-dozen on the operating floor above the point of origin.

Throughout his presentation, Orr referred to problems the mill had with managing the sawdust, particularly from the dry, beetle-kill pine it had been processing.

He said a five-person clean-up crew worked a graveyard shift, from 3:30 a.m. to noon, every weekday but was restricted to areas where the mill was not operating and the mill ran two 10-hour production shifts five days a week.

A weekend crew was also in place through a contractor, Orr said, but it usually could not get into the basement.

The severe cold also played a role as the temperature dropped to as low as -36 C in the days before the explosion and was -20 C at the time of the blast. The mill's windows were closed and fans located on the mill's east and west side - one that blew in, the other blew out - were off to keep the warmth in. The misting system, used to keep the dust from floating in the air, had been off since October, due to frozen pipes while the cold itself also significantly lowered the humidity, making for drier sawdust.

It got so bad that on the day before the explosion, the morning shift actually stopped production halfway through and workers were sent into the basement to clean out piles of dust and debris embedded in frozen water from burst pipes after it had been interfering with the machinery.

"They used jackhammers to break up the wood dust accumulation in the basement and started to move all that extra stuff onto the (conveyors)," Orr said.

But that work was cut short because the main conveyor had to be shut down so millwrights could work on a waterline along the mill's north side.

Production resumed with the afternoon shift and continued on the day of the explosion which occurred at 8:07 p.m. during the afternoon shift. It had been processing green wood on the day of the blast, as well as the day before, but had been putting through beetle-killed pine during the three previous days.

Orr also referred to a smaller February 2011 explosion at the mill, saying it was concluded sawdust accumulated within the panels of a motor control centre, where switches for turning machinery on and off are located, exploded and created a fire that caused about $500,000 in damage.

In response, Orr said the mill's owners, Oregon-based Hampton Affiliates, decided to have a pressurization system installed to keep dust out of the panels.

That work was completed in late November 2011 but it was soon shut down because it was kicking up dust in the sawmill creating more of a hazard.

As for theories that natural gas fueled the explosion, Orr said a leak was found 130 feet from the mill and there was no possibility of it migrating into the building.

The explosion did sever a natural gas line within the sawmill and it continued to leak for about

40 minutes, the inquest heard.

During the investigation, Orr said management staff told investigators the mill's dust collection system was large enough to handle only about half the sawdust the facility was producing.

Despite being one of the dustiest areas in the mill, the system did not serve the area where the blast originated.

Under the new owners, it had been redirected to other areas of the mill, while natural ventilation and cleanup crews were relied on to manage dust in the area which, according to WorkSafeBC's report on the blast, proved to be "ineffective for the volume and type of wood dust resulting from the extremely dry beetle-killed wood."

Hampton Affiliates had made a down payment on a used baghouse in Oregon for Babine but it had not been installed due to an inadequate power supply, according to WorkSafeBC's report.

"Throughout the fall of 2011, the power system was being upgraded, and this would have enabled the mill to upgrade the baghouse and collection systems in 2012," the report said.

The inquest is being held in the gymnasium of Island Gospel Fellowship in Burns Lake. About 35 people were in the gallery on Tuesday, including friends and family of Luggi and Charlie, as well as several of their co-workers.

The inquest is scheduled to hear from 48 witnesses over three weeks. An eight-person jury will then determine the cause of deaths and make recommendations to prevent similar incidents in the future.