Project status: Research and development is underway
Project partners: Metro Vancouver, FPInnovations, Lafarge, UBC Faculty of Forestry, Ecowaste, City of Vancouver, Tetra Tech
Project description: This project involves identification and sampling of pressure treated wood, to determine the degree to which the material is suitable for use as fuel in a cement kiln.
Pressure treated wood is treated wood where the chemicals are driven a short distance into the wood using a special vessel that combines pressure and vacuum.
In Canada, four different wood preservatives are registered with the Pest Management Regulatory Agency (PMRA) for industrial/commercial/agricultural use:
- Chromated Copper Arsenate (CCA)
- Pentachlorophenol (Penta)
- Ammoniacal Copper Zinc Arsenate (ACZA)
There are six wood preservatives currently registered with PMRA for treated wood in residential uses:
- Alkaline Copper Quaternary Compounds (ACQ)
- Copper Azole (Type A, CBA-A or Type B, CA-B)
- Micronized Copper Azole (MCA)
- Didecyl Dimethyl Ammonium Carbonate (DDAC)
- Disodium Octaborate Tetrahydrate (Borates)
Visual identification requires assessing the colour of the wood, and looking for other potential identifiers such as cracks and incising marks. It is not typically easy to distinguish safer types of treated wood (ACQ and CA) from the older types of treated wood that contained more toxic chemicals (CCA).
Identification and sampling were done at Vancouver Landfill and Ecowaste Landfill, where a visual approach was used to determine the total amount of treated wood in the load, and to select a piece for sampling, with 12 samples of pressure treated wood selected in total. Four of the 5 samples from Ecowaste Landfill were of creosote treated wood. Each sample was split into 2 and separated to allow for multiple testing methods to be used. One set of samples was laboratory analyzed for total organic carbon, soluble chlorine, calorific value, proximate and ultimate analysis and metals as part of the Lafarge alternative fuels package (test 1). The second set of samples was delivered to Metro Vancouver in Burnaby for further identification of the pressure treated wood using dye indicator testing (test 2).
There are positive indicators from test 1, in general, the calorific value was good and soluble chlorine levels were low, however there was significant variance in metal concentration across the samples which will need to be further investigated.
Engagement opportunities: Further research is needed to determine solutions for creosote, alternatives for pressure treated wood, and additional end markets for wood waste.