What To Do With Treated Wood Waste?

Hint: Request a hazardous waste disposal variance.

pressure treated lumber

As of January, 2021, there are very few options for the disposal of hazardous treated wood waste in California.

Furthermore, the limited options that do exist involve managing the treated wood waste as a fully regulated hazardous waste, which is procedurally more difficult and costly. For many generators, temporarily accumulating the treated wood waste is an available option that should be considered.

The state agency responsible for protecting California’s people and environment from toxic substances say they understand that “the change in status of treated wood waste and the sunset of the Alternative Management Standards has been disruptive and has caused frustration to many.”

“The DTSC (California Department of Toxic Substance Control) is aware of the urgency in resolving this problem and we are actively working on the variance application process.”

Used in fence posts, sill plates, landscape timbers, pilings, guardrails and decking, treated wood must now be disposed of in class 1 hazardous waste landfills, following the expiration of a law authorizing less onerous waste management standards.

After December 31, 2020, all treated wood waste “that exhibits the hazardous waste characteristic of toxicity will be a fully regulated hazardous waste and will no longer be eligible for disposal in Class II or Class III landfills,” a fact sheet from the California Department of Toxic Substance Control says.

Fortunately, on February 16 the department will start accepting requests for variances that allow the disposal of treated wood waste under the less onerous expired standards. The department is planning to issue the variances beginning on March 1.

In advance of activating the online variance application system, the department is releasing the application questions so prospective applicants can start gathering the information necessary to apply.

In the meantime, “the accumulation of hazardous waste for up to 90-days is generally authorized regardless of generator status,” the department’s treated wood waste FAQ states.

Depending on the manufacturing process and age, treated wood may contain a variety of toxic substances, including arsenic, chromium, copper, pentachlorophenol and creosote. In a 2019 report to the Legislature, however, the department notes that not all wood that is treated with a preservative is a potential hazardous waste.

A long-term solution is currently under consideration in the California Legislature. The Assembly Environmental Safety and Toxics Committee put forth AB 332 as a placeholder bill (meaning it has some broad stroke language, but not a lot of specifics yet) to address the treated wood disposal issue. The bill could, and likely will, become more detailed before it is heard in committee. CLCA will continue to monitor the proposed legislation. Look to future issues of The Cutting Edge for more information.


Contractors working with treated wood now have a new online resource to help stay in compliance with state regulations. The Western Wood Preservers Institute’s twwdisposal.org site provides important information on reporting, recordkeeping, storage and disposal.
Updated April 1, 2022

Problem solved? Read about the new law that provides good news for disposers of treated wood waste. READ >
Updated September 5, 2021

Good news for landscape contractors storing a growing pile of treated wood waste in their corporate yards.
The Department of Toxic Substances Control has started to issue hazardous waste disposal variances for haulers, handlers and landfills for treated wood waste. For example, Sacramento County just announced that their Kiefer landfill will now accept that waste.
There is a bit of lag time, it seems, from when the variance is approved and it makes these lists:
Updated 3 p.m., April 9, 2021


CLCA Recommends

  • For the time being, don’t panic – and keep an eye out for updates from CLCA on this important matter.
  • Carefully review the California Department of Toxic Substance Control’s Treated Wood Waste fact sheet, paying particular attention to the section detailing how treated wood waste must be managed in accordance with full hazardous waste management standards.
  • Ascertain the cost of obtaining a disposal variance and determine if a variance request is the best course of action for your company.
  • Consider storing treated wood waste for 90 days in the hopes that a legislative solution is forthcoming.