Assessing Potential Waste Disposal Impact from Preservative Treated Wood Products

The management of discarded treated wood products upon disposal is one of the many factors that should be considered when evaluating a new wood preservative or when comparing wood preservatives as part of a life cycle assessment. Future environmental ramifications of disposal, as well as regulatory requirements and costs, must be assessed and weighed. This paper presents an overview of the factors that must be evaluated when assessing the disposal issues associated with discarded treated wood products. The discussion is based on current US regulations and policy, but the general approach toward evaluating disposal issues will be valid for most countries. A primary consideration is whether a wood preservative has the potential to cause a treated wood product to be a hazardous waste. Only a limited number of compounds can cause a solid waste to be a regulatory hazardous waste, and since the costs of hazardous waste management are high, this should be examined critically. Discarded treated wood products that are not hazardous may still pose environmental and regulatory concerns. Impact on landfill disposal, combustion systems, and wood recycling operations should be addressed. The concepts described in the paper are illustrated by examining four treated wood types: chromated copper arsenate, alkaline copper quaternary, a commercially available borate-treated product and a hypothetical treated wood product containing a silver-based biocide.