Deadly BC wood dust explosions place emphasis on precautions

Deadly BC wood dust explosions place emphasis on precautions

By Jim Chisholm, P.Eng.,
Fire Protection Engineer, OFMEM

Facilities that produce combustible dusts need to have precautions and controls to prevent an accumulation of dust. Otherwise combustible dust can collect, get into the air of the production facility and potentially create an explosive environment. Unfortunately, in North America, there have been many examples where proper precautions and controls have not taken place. This has resulted in tragic explosions from the combustible dusts. The latest tragic examples occurred in British Columbia wood working plants. Two separate explosions involving combustible dusts killed four workers.

In Ontario, Section 5.10, of Division B of Ontario’s Fire Code deals with combustible dust producing processes. It outlines the minimum precautions that need to be undertaken where combustible dusts are produced in buildings or parts of buildings in quantities or concentrations that can create an explosion or fire hazard.

Four workers killed in explosions

In 2012, British Columbia experienced two deadly incidents at sawmills: two workers were killed and 20 injured at Babine Forest Products in Burns Lake in January and at Lakeland Mills in Prince George in April, two more workers were killed and 22 injured. Both facilities were destroyed by explosion and fire.

The two explosions resulted in WorkSafeBC doing a major investigation into the causes of the explosions and fires. (WorkSafeBC is the Occupational Health and Safety and Workers Compensation authority in British Columbia.) On November 29, 2012, they submitted the findings of their investigation to the Crown Counsel for consideration of possible charges under the Workers’ Compensation Act. This paper made the following key points about the similarities of the two explosions:

  • Wood dust was the fuel for the two explosions
  • The explosions in both mills originated in spaces at the lower levels where conveyor systems were receiving and moving wood waste
  • Friction from gear reducer-motor sets has been identified as the likely ignition source in both explosions {Click Gear Reducer Hazard to view special hazard alert from WorkSafeBC}.
  • Doors and windows were closed and humidity levels were low or had been low prior to the explosions. {Click Combustible dust winter alert - increased risk in winter to view special hazard alert from WorkSafeBC on increased risk of dust explosion at low humidity levels during winter};
  • The explosions in both mills occurred around meal breaks and band saw changes.
  • Both mills were processing significant amounts of beetle-kill wood. This wood arrived at the mills much drier than other wood. (WorkSafeBC had previously reported on August 16, 2012 that laboratory test results concluded that beetle-kill wood dust posed a high risk of explosion when the moisture content of the dust is below five per cent and particle size is less than 75 μm (micrometers).)

Recommendations

On January 15, 2013, WorkSafeBC issued a Recommendations Report based on their investigation into the Babine Forest Products incident. It made the following three recommendations to owners and operators of wood processing facilities:

  • A facility assessment for combustible dust must be done to identify hazardous locations
  • Where hazardous locations are identified and contain regulated equipment, document a plan to either
  • Manage the combustion hazard by developing and implementing auditable wood dust management practices or
  • Configure the equipment for safe operation
  • Incorporate any identified hazardous locations and the chosen means to manage the combustion hazards into the facility’s Fire Safety Plan.

Directive Order from WorkSafeBC

These three recommendations build upon an April 26, 2012 directive order from WorkSafeBC to all of the 173 sawmills in the Province to:

  • Conduct a full hazard identification, risk assessment, and safety review, with particular focus on combustible dust; dust accumulation and potential ignition sources
  • Carry out a thorough risk assessment with respect to combustible dust hazards
  • Develop a dust control program that reflects the assessment and
  • Ensure the program is being implemented, including ensuring workers are educated and trained.

Follow-up

WorkSafeBC reports that they have been following up with employers to ensure the legally binding ordered actions are being undertaken and that sawmills are in compliance with the Workers Compensation Act and Occupational Health and Safety Regulation with regard to combustible dust and potential safety hazards.

The Office of the Fire Marshal and Emergency Management (OFMEM) will continue to monitor for further releases from WorkSafeBC in regard to their investigation of the two explosions and their ongoing inspections and abatement activity in the wood working sector.

More information

Further information about the Babine and Lakeland explosions can be seen at WorkSafeBC web site at:

http://www.worksafebc.com/news_room/features/2012/sawmills/default.asp

Information about occupational health and safety standards that may apply to the wood working sector can be found at the Ontario Ministry of Labour web site:

http://www.labour.gov.on.ca/english/hs/

Enquiries regarding the dangers of combustible dusts should be directed to Jim Chisholm, Technical Services, OFMEM at Jim.Chisholm@ontario.ca.