All dust poses risks for mills: WorkSafeBC
As it continues its investigation into the catastrophic explosions in Burns Lake and Prince George earlier this year, WorkSafeBC has revealed that its testing so far shows that all wood dust, not just beetle-kill wood dust must be rigorously managed by sawmills.
By John Tenpenny
Today’s update is not specific to the investigations and its relevance to the cause and underlying factors of the explosions is yet to be determined.
As part of its ongoing investigations, WorkSafeBC collected samples from various mills across BC for various reasons. In July green-wood dust samples were submitted to a US laboratory for comparative analysis with beetle-kill wood which is being investigated as a potential fuel source in the two explosions.
Those test results show that, like beetle-kill wood dust, green wood dust that has a moisture content below 5% and a particle size less than 75 micrometers poses a high risk for explosion when dispersed and ignited in air. These properties are consistent with the properties of dust that is found on elevated surfaces such as rafters and beams, inside dust collectors, and on the surface of air separation media. It is also found in hot, dry environments such as process equipment and light covers.
This information reinforces the direction previously issued to industry regarding the importance of rigorous management procedures for all wood dust, not only beetle-kill.
Worksafe is on target to complete its investigations of the Babine and Lakeland explosions by October.
Phase I of Worksafe BC’s combustible dust strategy was initiated in April 2012 focussing on primary sawmills. Phase II began July 5, 2012 whereby the strategy was expanded to include planer mills, pellet plants, and wood processing operations where dust accumulation could be a safety hazard.
Worksafe plans to have prelminary Phase II results posted on its website later today.
Until the end of the year, WorkSafeBC officers will be inspecting up to 280 B.C. employers registered in the wood and paper products subsectors. Inspections will focus on dust cleanup, ventilation, and dust control issues.
Phase II inspections will also include sawmill facilities inspected as part of Phase I, that are continuing to face challenges in maintaining compliance.
There was no indication from WorkSafeBC on whether the potentially higher volumes of very dry dust produced in primary mills processing older beetle kill wood poses an abnormally high risk, and if so what procedures or equipment should be adopted.