Timber Turn-Ins: Disposing of Preservative-Treated Wood

We all know where to recycle our empty bottles, cardboard boxes, and plastic packaging, but where does preservative treated wood go?

Treated wood is not listed as a hazardous waste under Federal law, and it can be disposed of in any waste management facility authorized under State and local law to manage such material. State and local jurisdictions may have additional regulations that impact the use, reuse, and disposal of treated wood and treated-wood construction waste, and users should check with State and local authorities for any special regulations relating to treated wood.

FPL's Steve Halverson working in the pressure treatment facility.

FPL’s Steve Halverson working in the lab’s pressure treatment facility—but where will this treated wood end up?

Treated wood must NOT be burned in open fires or in stoves, fireplaces or residential boilers, however, because the smoke and ashes may contain toxic chemicals. Treated wood from commercial and industrial uses, for example, from construction sites, may be burned only in commercial or industrial incinerators in accordance with State and Federal regulations.

Spent railroad ties treated with creosote and utility poles treated with pentachlorophenol can be burned in properly equipped facilities to generate electricity. As fuel costs and energy demands increase, disposal of treated wood in this manner is becoming more attractive, however, it poses more challenges with wood treated with heavy metals (which remain in the ash for further processing).

Researchers have demonstrated that wood treated with heavy metals can be chipped or flaked and reused to form durable panel products or wood-cement composites.

Techniques for extraction and reuse of the metals from treated wood have also been proposed, including acid extraction, fungal degradation, bacterial degradation, steam explosion, or some combination of these techniques. All of these approaches show some potential, but none are currently economical. In most situations, landfill disposal remains the least expensive option.

Reuse of treated wood may be a viable alternative to landfill disposal, and in many situations, treated wood removed from its original application retains sufficient durability and structural integrity. Generally, regulatory agencies recognize that treated wood can be reused in a manner that is consistent with its original intended end use. The biggest obstacle however is the lack of an efficient process for collecting and sorting treated wood.

The city of Baltimore, Maryland, has 16,000 vacant homes. Reclaiming materials through deconstruction and establishing market outlets can create value where not currently exists.

The city of Baltimore, Maryland, has 16,000 vacant homes. Reclaiming materials through deconstruction and establishing market outlets can create value where not currently exists.

Researchers at the Forest Products Laboratory (FPL) hope to change this in the future. Pilot studies have already been conducted to develop cost-effective methods to collect, sort, and reuse wood (including treated wood) from urban areas. In addition to conserving resources and helping the environment, these methods have the added benefit of stimulating local economies with new jobs and industries.

Disposing of treated wood in a responsible way may not be as simple as a trip to your local recycling center, but it is still an important part in the life-cycle of the material that must be considered to ensure wood remains a sustainable, environmentally friendly resource.