B.C. Air Quality

Slash and Wood-Residue Burning

The forest industry uses burning to dispose of leftover slash and wood residue to abate fire hazards as required under the Wildfire Act and Wildfire Regulation. The obligation to abate fire hazards does not require forestry operators to burn the debris, just dispose of it. In some cases, burning is the best option, as long as it is carried out so as to minimize air pollution — following the rules set by the Open Burning Smoke Control Regulation. In other cases, woody material can be used to make such products as mulch and wood pellets, and for cogeneration.

Note: The Ministry of Environment is reviewing and revising the Open Burning Smoke Control Regulation. See Proposed Changes to the Open Burning Smoke Control Regulation.

Slash Burning in the Forest Industry

Slash is the leftover tree limbs, tops and other residue left by logging activities. Slash is disposed of, by burning, in two ways:

  • in piles: slash is piled together and burned during safe conditions, usually during the winter after it has been left to season (dry); and
  • through broadcast burning: the limbs and tops, and other residue are burned as they lie on the ground after cutting. The slash must be distributed continuously throughout the burn area to be burned effectively. Burning is generally done during very wet periods or with light snow cover in late fall or early spring.

Piled slash burning is covered under the Open Burning Smoke Control Regulation. The regulation establishes strict rules on what can and can't be burned in land-clearing fires, where they can be located, the atmospheric venting conditions that must be present, and how long the burning can last. For more information, see Regulations and Bylaws on Outdoor Burning and a Guide to the Open Burning Smoke Control Regulation. Resource management open fires (broadcast burns) are covered under the Wildfire Act and Regulation. They require a burn plan.

Wood Debris Burning in Log Sorts

Wood debris from log sorts is disposed of through open burning. Stumps and roots encrusted with mud may be burned, resulting in dense smoke. This kind of burning is currently allowed through permitting, but may be subject to the Open Burning Smoke Control Regulation in the future.

Wood Residue Burning in the Forest Products Industry

Most B.C. sawmills burn the trim ends, slabs, bark, shavings and sawdust left after the logs have been cut. There are three problems with this practice:

  • The burning is often done inefficiently, releasing a lot of smoke. As a result, the emissions from sawmill residue burners (beehive and silo burners) cause frequent episodes of air pollution for many small communities, limiting visibility and leading to health problems.
  • A significant amount of sawmill wood residue in B.C. is being wasted, simply being disposed of by burning.
  • This material can be used as a beneficial byproduct. For example, it can fire cogeneration plants that generate electricity and (steam) heat for pulp mills. It can also fire biomass power plants (e.g., Williams Lake Power Plant), which provide electricity for B.C.'s power grid. In addition, wood residue can be used as chipping for pulp and fibreboard mills, and to make such products as particle board and wood pellets.

Wood residue burning is controlled by the Wood Residue Burner and Incinerator Regulation. This regulation requires that wood residue burners are to be shut down according to a phaseout schedule. Under action #19 of the B.C. Air Action Plan, the government will eliminate the remaining beehive burners by 2010, starting with those near residential areas. This will remove over 14,000 tonnes of fine particulate matter from our air.

The wood residue that will no longer be burned can be used to generate electricity: see BC Hydro to advance bioenergy production to utilize wood fibre. It can also be used for cogeneration, and to manufacture a range of products, such as particle board, mulch, and wood pellets for wood stoves and fireplaces.

To find out when it's environmentally safe to burn, see Ventilation Index.


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