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Wood processing in British Columbia: Under the beetle’s shadow

Author : Alan Franck, HazardEx Editor

13 September 2012

Two sawmill explosions earlier this year have cast a long shadow over the British Columbia wood processing industry, already in difficulty because of the mountain pine beetle epidemic that has killed many of the forests from which its timber is sourced. Could those very same beetles also bear some responsibility for the blasts? 

The mountain pine beetle epidemic has already killed 59% of the Interior pine forests of British Columbia, according to some estimates
The mountain pine beetle epidemic has already killed 59% of the Interior pine forests of British Columbia, according to some estimates

The January and April explosions and fires respectively at Babine Forest Products in Burns Lake and Lakeland Mills in Prince George killed four workers and injured a further 41.

“We are in new territory,” said John Allan, president of the BC Council of Forest Industries (COFI), after the Prince George incident. “These two mills blew up: they didn’t just catch fire.”

Initial investigations pointed to a strong possibility that the blasts had been caused by the ignition of a cloud of fine sawdust within the mills, causing massive dust explosions. 

After the April incident, the province’s occupational safety agency, WorkSafe BC, issued an order that all British Columbia’s sawmills should conduct a thorough inspection of their facilities and implement an effective combustible dust control programme within two weeks. The industry also commissioned new research to determine what a safe level of dust in sawmills might be. 

WorkSafe BC has since found evidence of five other unreported incidents, including an earlier incident at Burns Lake.

Beetle-killed timber sawdust – the smoking gun?

A particular focus of investigators is into sawdust from dry wood killed by the mountain pine beetle epidemic in British Columbia’s Interior.

The dust produced when processing beetle-killed pine is finer and contains far less moisture than sawdust from recently-felled timber.  “There is no question, discussing this within the industry as we have, that the dust properties are different,” said Roberta Ellis, Senior Vice President of WorkSafe BC. 

About 70% of the two mills’ wood supply was beetle-kill, and fire inspectors have sent sawdust samples to laboratories for particle size evaluation and to check the minimum concentration required to set off an explosion. Initial models show that beetle-killed wood shatters more than green wood when sawed, creating a cloud of fine particulate that is not just dry but also full of resin.

Sawdust, wood shavings and chips have fuelled dozens of fires at BC sawmills over the past decade. Sawdust was listed as the material which first caught fire in more than half of 89 sawmill fires in Interior BC between 2001 and 2011, according to BC Fire Commissioner incident reports obtained by The Vancouver Sun.

It was ignited most often by sparks (52%), followed by friction heat (25%), hot objects and direct flame (both 8%).

The sources of the ignition included bearings, electric panels, welding equipment, cutting torches, wiring, general machinery and in one case a halogen lamp.

In an interim note issued in mid-May, WorkSafe BC warned forestry sector companies that the ignition sources for the two fatal sawmill explosions took place in “contained areas” housing electrical and mechanical equipment in the basement or lower levels of the two mills.

Canadian forestry consultants IWM say 22 mills have closed in British Columbia since 2005, and by 2018, up to 16 of the province’s remaining 90 mills are likely to follow suit
Canadian forestry consultants IWM say 22 mills have closed in British Columbia since 2005, and by 2018, up to 16 of the province’s remaining 90 mills are likely to follow suit

A contained space is one of five elements needed to create a dust explosion - the others are dispersion of an explosive agent, fuel, ignition and oxygen.

Dust suspended in the air burns more rapidly, while confinement allows for pressure to build up. Also, the initial blast can cause dust that has settled over time to become airborne, resulting in a larger secondary explosion. WorkSafe BC’s Best Practice guide, updated in April 2012, says that settled layers of sawdust in the plant should not be allowed to exceed 3mm.

Three years ago, in a report dated February 3, 2009, the agency specifically warned of the danger of dry wood killed by pine beetles, and noted an absence of monitoring exposure of wood dust in processing saws and chipping heads in the plant.

Nevertheless, the agency and its partners are careful not to leap to any premature conclusions on the definitive causes of the Babine and Lakeland explosions, with investigations likely to take many more months before final conclusions are published. Other avenues than dust are also being explored – a WorkSafe BC investigation update on the Babine fire released in May focused on possible natural gas line or propane leaks. 

Also, on June 22, soil tests at the Lakeland site detected methane, causing the immediate shutdown of the recently reopened planer mill and closure of the mill energy system, which provided heat to some local businesses. Twenty-eight employees, who had only been back at work for six weeks, again lost their jobs.

In response to WorkSafe BC’s initial directive, 173 sawmills throughout the province took internal mitigating measures to reduce or eliminate dust accumulations in their operations, according to the agency. At least 11 had hazardous levels of wood dust, and some were closed temporarily until the dust situation was remedied.

Phase II of the agency’s combustible dust strategy began in early July and has been expanded to include all wood processing operations where dust accumulation could be a safety hazard.

Until the end of the year, WorkSafe BC officers will be inspecting up to 280 BC employers registered in the wood and paper products sub-sectors. Inspections will focus on ventilation and dust control issues.

The largest wood product-manufacturing companies in BC have also announced an unprecedented collaboration to create a joint safety-improvement action plan. The companies will establish a task force to quantify combustion risks related to dust from processing both green and dry wood, along with clear standards and management practices for dust control in a wood plant environment. When standards and process safety management practices have been agreed, they will be rolled out to every mill in the province.

An unprecedented epidemic

The sawmill explosions come at an already difficult time for the logging and timber-processing industries in western Canada.

A recent report by Vancouver-based consultants International Wood Markets (IWM) estimated that the mountain pine beetle epidemic has already killed 59% of the Interior pine forests, and that time was running out for sawmills to economically process that wood into lumber. 

The current beetle epidemic started in the late 1990s, and the sawmills try to cut standing dead trees within eight to 12 years of infection. After that, the dead timber becomes marginal for sawmilling, and soon after, even for plywood operations. The affected areas are so huge that in some areas, loggers’ clearance activities have barely scratched the surface.

The BC Ministry of Forests, Lands and Natural Resource Operations estimates that the mountain pine beetle has now killed a cumulative total of 710 million cubic metres of timber since the current infestation began. It says the cumulative area of the province affected, either partially (red stage) or totally (grey stage), is estimated at 18.1 million hectares.

A recent Ministry report said that some parts of the province had about five years of economical pine-beetle harvest remaining, while others are down to one and a half years’ supply.

Newly attacked lodgepole pine trees turn red about one year after infestation. Trees can stay in the red-attack stage for two to four years before turning grey as they lose their needles and die.

On a provincial level, the infestation peaked in terms of volume killed annually in 2005 and has slowed considerably since then. In terms of area, 4.6 million hectares of red-attack were surveyed in 2011.  This is compared to 7.8 million hectares and 6.3 million hectares in the two preceding years.

The reduced rate of attack is attributed to the diminishing amount of habitat available to the beetle, as it has already infested most of the mature lodgepole pine in the Central Plateau region, according to the Ministry.

North America’s north-western montane forests are the scene of what scientists consider to be the worst bark beetle epidemic ever.

The US Government’s FireScience Digest says mountain pine beetles and spruce beetles have attacked lodgepole pine and Engelmann spruce over millions of hectares throughout the subalpine zones of the Rockies and have killed between 60% and 80% of the mature trees in some areas. 

The Digest says what is particularly concerning about this outbreak is that the beetles are pushing into new territories such as northern British Columbia, on the extreme edge of the mountain pine beetle’s historical range. The beetles have also crossed the spine of the northern Rockies, apparently for the first time, and are now resident in Alberta jack pine forests. They could well spread into other tree species that did not co-evolve with these beetle species and consequently have no defences against it.

Bark beetles have also spread upslope into alpine forests of whitebark and bristlecone pines, where cold temperatures have historically kept them out. 

The main factor in these new dynamics is a warming climate, the Digest says. Earlier snowmelt, a longer growing season, and milder winters favour an environment that drives beetles to reproduce more often in a season and allows more larvae to survive the winter. Another factor is that reduced rainfall stresses the trees and makes it harder to fight a beetle infestation. 

Beetles do not in fact kill the trees themselves, but introduce a blue fungus into the sapwood that prevents the tree from repelling the attacking beetles with tree pitch flow. The fungus also blocks water and nutrient transport within the tree.

Mountain pine beetle (Dendroctonus ponderosae)
Mountain pine beetle (Dendroctonus ponderosae)

A perfect storm

COFI president John Allen said the sawmill explosions were the latest blow to an industry already under siege by the mountain pine beetle. 

“The beetle has infected every aspect of the business. We have the arbitration with the United States (over US allegations that BC is violating the Softwood Lumber Agreement by charging mills too little for beetle-killed wood). It is potentially a safety issue and it certainly is an economic issue for us.”

British Columbia mills expect to see a reduction in timber harvest and production of between 35% and 50% in the long term, according to IWM’s May newsletter.

The consultants said 22 mills had closed in the province since 2005, and by 2018, up to 16 of the province’s remaining 90 mills will close due to a lack of saw logs.

Also, following this year’s mill explosions, the Flavelle sawmill in Port Moody saw its insurance premium climb from $300,000 to $1.1 million. That mill closed, and others are facing premium increases of up to 400%.

So the contraction in log supply comes at a time of rapidly rising safety and insurance costs, creating a perfect storm for the industry. The logging and forest products industry is the second most important in British Columbia and observers say these developments could result in thousands of job losses over the next five years, often in small Interior towns where there is little alternative employment.

A confidential government report that was leaked to the media projected economic and social meltdown, with 12,000 Interior jobs disappearing within five years.

The IWM May report says the mountain pine beetle epidemic is responsible for one of the largest natural environmental catastrophes ever seen. The US Government’s Fire Digest concurs, adding that it could well be the most damaging result of global warming experienced in North America to date.

But despite this, British Columbia forestry industry president John Allan says everyone involved should retain a sense of perspective. "After it’s over there'll still be a forest industry. We are efficient, we're good at what we do, we're cost competitive, there's lots of wood out there. There's just not going to be as much wood in the future as there is today."

Meanwhile, the race is on to discover the primary causes of the sawmill explosions at Burns Lake and Prince George. If beetle-killed wood is indeed found to have been a factor, this will highlight the need for constant vigilance in situations where the nature of combustible dusts within a processing environment changes over time.


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