08/16/2012 11:59 EDT | Updated 10/16/2012 05:12 EDT

Two types of wood dust linked to B.C. sawmill explosions

Dust from green wood, as well as pine beetle wood, likely contributed to two fatal explosions at the Burns Lake and Prince George sawmills earlier this year, according to an investigation by WorkSafe BC.

Results of U.S. laboratory tests conclude that both types of dust pose a high risk of explosion under very dry conditions, WorkSafe BC said.

"It's important that operators who are processing green wood not feel complacent that beetle-kill wood is the problem," said Roberta Ellis, a senior vice president with WorkSafeBC.

Four people died when the Babine Forest Products sawmill in Burns Lake, B.C., and a mill in Prince George burned down earlier this year.

Investigators still don't know what sparked the massive explosion and fire in both incidents.

The industry has already been warned about the importance of dust management in keeping mills safe, but investigations director Jeff Dolan says further research is needed.

“We still have one or two other fuel sources that we need to rule out beyond a reasonable doubt,” Dolan said, which could include natural gas, propane and other gas sources.

A final report is expected this fall.

The company that owns and runs the Burns Lake mill — Hampton Affiliates — says it will make a final decision in 30 days on whether it plans to rebuild the Babine Forest Products sawmill, which burned to the ground in January.

The company says it wants a secure supply of timber before it considers rebuilding.

Yesterday, the Special Committee on Timber Supply released its report saying the fibre supply — or the number of trees — is more than they expected.

"There will be a sustainable cut in the [Burns Lake] Timber Supply Area of just over a million cubic metres per year, which is more than double what the expectation is currently,” said committee chair John Rustad.

Rustad also pointed to other options, such as logging areas infested by the mountain pine beetle.