New Rules Regarding Treated Wood Waste

New rule will prevent local waste disposal sites from accepting treated wood

Effective Jan. 1, 2021, the California Department of Toxic Substances Control (DTSC) will no longer allow the landfill disposal of treated wood waste (TWW). This means that transfer stations and rural container drop-off sites can no longer accept TWW for disposal after Dec. 31. 

In response to expiring legislation, the DTSC announced the current statute and regulations are set to expire and households and businesses will be required to dispose of this material as hazardous waste.

Transfer station personnel will perform load checks and have been instructed by the state to reject any treated wood waste. 

Treated wood waste comes from old wood that has been treated with chemical preservatives. These chemicals help protect the wood from insect attack and fungal decay while it’s being used. Fence posts, sill plates, landscape timbers, pilings, guardrails and decking are examples of chemically treated wood. TWW contains hazardous chemicals that pose a risk to human health and the environment if they leach out of regular solid waste landfills.

Arsenic, chromium, copper, creosote and pentachlorophenol are among the chemicals used to preserve wood and are known to be toxic or carcinogenic.

Starting Jan. 2, Humboldt Waste Management Authority’s (HWMA) Hazardous Waste Facility will begin accepting treated wood waste.

Residential customers may bring up 125 pounds per day. Sections must be less than 3 feet in length with nails, staples, screws and other fasteners removed whenever possible to do so. 

Small businesses are encouraged to call HWMA at 707-441-2005 for information on volume restrictions and costs. 

For more information, residents and businesses can visit DTSC’s website at

Questions regarding TWW can be sent to: or