There are currently no laws against throwing out small amounts of pressure treated wood with your regular trash. Nor are there any specific federal government regulations for proper pressure treated wood disposal, although many state and local governments have laws against certain improper treated wood disposal methods. That said, even if you don't have government regulators and law enforcement looking over your shoulder, it's still wise to take the extra few moments to dispose of pressure treated wood in a conscientious and environmentally responsible manner.
The reason why is simple: pressure treated wood contains a number of hazardous chemicals that can release into the atmosphere, both air and soil, and do harm to the environment and the life in it, including you and me. The wood pressure treatment process, as defined by the American Wood Preserver’s Institute, is using pressure to force chemical preservatives deeply into the cellular structure of the wood. There are many different types of pressure treated wood that must be disposed of safely, including:
- Chromated Copper Arsenate (or CCA treated wood)
- Ammoniacal Copper Quaternary (or ACQ treated wood)
- Ammoniacal Copper Zinc Arsenate (or ACZA treated wood)
- creosote treated wood
- oil borne preservative treated wood, such as with pentachlorophenol (or “penta”)
How Not to Dispose of Pressure Treated Wood
Whatever method of disposal of treated wood you choose, do not burn it, grind it up, or recycle it.
Burning treated wood releases a number of toxic chemicals into the atmosphere that impact air quality. Pressure treated wood should never be used as firewood. Some states even have laws against open burning pressure treated wood.
The process of grinding pressure treated wood into mulch is just as bad. Some of the chemicals release into the air in the form of toxic dust, and the rest of the chemicals leach into the soil beneath the mulch. Likewise, keep all treated wood chips, sawdust and scraps out of your compost, as you'll just poison whatever you eventually try to grow with it and release volatile organic compounds into the air when the compost off-heats.
Nor do you want to recycle pressure treated wood. That means don't place treated wood in your paper recycling or drop it in the wood recycling bin at your local waste transfer station, as these same chemicals used to preserve pressure treated wood will taint the reusable material in with it.
There is a difference, however, between recycling and reusing—more on that in a moment.
The Safest Method
To get rid of pressure treated wood in the safest way for the health of the environment and its inhabitants, take it down to the nearest Department of Environmental Protection (DEP) approved landfill and place it in the properly labeled container.
Admittedly, while this may be the safest means of treated wood disposal, it is not necessarily the quickest or easiest means. It does take a little effort on your part, and if you're going to put your effort into proper treated wood disposal anyway, you might as well go all the way and make use of it yourself.
The Best Method
The best way to dispose of pressure treated wood is to reuse it for other purposes yourself. You may not be able to recycle pressure treated wood for someone else to make use of, but you certainly can make all the use you want of it yourself. Start a pile in the garage, basement or shed. You never know when you may want to build a bookshelf, a planter box, or some other piece of small home carpentry.
Besides giving you free material to work with in your next DIY woodworking project, reusing pressure treated wood saves you the time, effort and cost of gas to haul the wood down to the closest DEP approved landfill. It also saves on the economic and environmental impact of the processes the landfill uses to properly finish disposing of the treated wood from there.
Just remember, when you work with the pressure treated wood again to be sure to wear goggles and a respirator or face mask before you cut or sand it. Be sure to clean up and dispose of any sawdust you produce properly.
Remember, pressure treated wood that doesn't enter the waste stream isn't waste.
Connecticut Department of Environmental Protection: Proper Use and Disposal of Treated Lumber <https://www.ct.gov/dep/cwp/view.asp?a=2714&q=324870>
Western Wood Preservers Institute: Management and Disposal of Treated Wood Waste in California <https://www.wwpinstitute.org/mainpages/documents/GuidanceDocumentforDisposalofTreatedWoodWasteinCalifornia.pdf>
State of Hawaii Department of Health: Pressure Treated Wood Management <https://hawaii.gov/health/environmental/waste/sw/pdf/trtdwood.pdf>
Image: Eric Guinther (Wikimedia Commons) <https://commons.wikimedia.org/wiki/File:Landfill_Hawaii.jpg>