Treated wood refers to any wood that has been treated with a chemical preservative to protect it from microorganisms, insects, or fungi that may lead to decay or deterioration of the wood.
Surface-applied coatings, such as varnish, oil stain, and paint are not considered wood preservatives.
When looking to dispose of treated wood, it becomes referred to as treated wood waste, which may include products that have been permanently removed from use, such as docks, decks, timbers, and fences, or treated wood debris, such as scraps, sawdust, and trimmings.
Treated wood product waste is generally considered to be nonhazardous. However, it should still be disposed of with caution by following these steps:
Step 1: Identify whether the wood waste has actually been treated with a preservative
Here are a few tips to help you identify if the wood has been treated:
- The wood contains an end tag or ink stamp indicating treatment.
- Treated wood used in industrial or construction applications is usually incised to boost treatment. So, look for small, closely spaced cuttings on the full surface of wood to determine if it’s treated.
- Materials that have not been painted or stained tend to appear greenish in colour, while those used in transportation and industrial systems tend to have a dark brown hue and slight petroleum smell.
- Examine the crosscut section of the wood. If treated, it should have a darker hue in the outer .25 to 1 inch.
- The type of project in which the wood was used, as well as what it was specifically used for may also suggest whether it was treated or not. For instance, if it was in contact with water or ground, or even exposed to the elements, yet it is not a decay-resistant species like cedar and redwood, then it is possible that it’s treated.
Step 2: Dispose the treated wood waste
Once you establish that the wood is treated, do not burn it, discard it on the land, or even use it as ground mulch. Instead, you can:
- Use it as fuel in specifically approved co-generation facilities.
- Deliver it to a permitted landfill. But always contact the landfill before delivery to establish if there are any limitations, as some may require approval by the Regional Water Quality Control Board.
- Treated wood from residential use may be sent to approved landfills, a local household hazardous waste collection centre, or a transfer station.
Caution when handling treated wood
It is important that you wear protective attire when handling treated wood to avoid any contact with skin. This includes gloves, long sleeved shirts, eye protection, and even a dust mask. Any exposed areas of the skin should be washed thoroughly with water and mild soap.