B.C. Premier Christy Clark has ordered a review of the investigation into the Babine Forest Products sawmill explosion and fire in Burns Lake, B.C., that claimed two lives and injured 20 others in January 2012.

The long-awaited WorkSafeBC report released Thursday finds the disaster could have been prevented if mill management had been doing its job.

No criminal charges are being laid, however. Last week, Crown counsel revealed it would not bring charges against the owners of the mill, saying WorkSafeBC's investigation didn't follow the rules for conducting criminal investigations and as a result a large amount of evidence would have to be thrown out.

Clark says the people of Burns Lake deserve an explanation.

"That's why I've asked the head of the BC Civil Service, Deputy Minister John Dyable, to review the case — to review the fact pattern, come back and give us the facts so that we know and understand what happened with the investigation and the decisions around it."

Mill management blamed

In the final report of its investigation into the incident, WorkSafeBC says sawmill management had known for some time that the dust collection system was undersized for this type of operation and had even made a down payment on a replacement.

The accumulations of wood waste before the explosion … indicates that supervisors were not effectively or adequately monitoring the work that was being done. -WorkSafeBC report

Unfortunately, the mill's electrical supply could not handle the additional load of the new dust collection system.

"An electrical upgrade was planned, but instead of curtailing production until the upgrade was complete, production levels were increased instead."

The 87-page report finds the explosion was caused by a buildup of wood dust that was ignited by rotating belts near a conveyor-belt motor.

A view of the conveyor belt assembly shows sawdust accumulation. (WorksafeBC repôrt)

"The dust was compacted and subjected to near constant friction from the rotating belts and sheaves. It caught fire and ignited the airborne wood dust that was dispersed in the area. An explosion and subsequent fire travelled through the mill, disturbing and dispersing the accumulated wood dusts and setting off secondary explosions that totally destroyed the mill, killing two workers and injuring 20, many seriously."

The WorkSafeBC report puts the blame squarely on a lack of supervision.

"The accumulations of wood waste before the explosion and the poor condition of some of the electrical equipment that was inspected after the incident indicate that supervisors were not effectively or adequately monitoring the work that was being done."

Workers deaths examined

The report also looks at the circumstances surrounding the death of the two workers. It says the booth operated by the cut-off saw operator was directly in the path of the explosion as it expanded north and west, fed by the wood dust in the air.

An aerial view shows the east side of the sawmill. The large yellow arrow indicates the easterly direction of the explosion’s expansion from the point of origin (WorksafeBC report)

"The over pressure (from the explosion) breached the north wall and vented outward into his location. The operator’s booth was destroyed and the #1 Cut-off Saw Operator died while still in the booth."

The report says the lead hand was found inside the doorway of the round saw filing room in the sawmill's basement where he had gone to perform a variety of system checks.

The mountain pine beetle-killed wood used by the mill may have also been a factor in the accumulation of dust in the mill. The report finds that decreasing amount of moisture in dead pine adds challenges to industrial sawmill operations.

"The various statements from the Babine mill workers certainly indicate that beetle-killed wood was producing more and finer dusts and waste than typical green wood."

WorkSafeBC recommendations

The worker safety agency says it's taking the following steps to prevent future disasters:

A directive order to every sawmill in B.C. to undertake a comprehensive risk assessment with respect to hazards created by combustible dusts and develop and implement an effective combustible dust control program.

Followup inspections of sawmills by WorkSafeBC prevention officers.

The expansion of inspections to similar wood-processing operations where dust accumulation could be a hazard.

The issuance of hazard alerts on the increased risk in winter of combustible dust.

Read the full WorkSafe B.C. report

WorkSafeBC says its report only addresses the cause of the sawmill explosion. However, it is currently considering enforcement action against the company under the Workers Compensation Act.