Disposal of Treated Wood Waste (TWW) in California

Author: Marketing
Date: February 3, 2024

What is Treated Wood Waste

Treated Wood Waste (TWW) is waste from wood products intended for outdoor use or for wet areas that has been treated with preservatives to prevent rot or decay.  Examples of these wood products include:

  • Utility poles, fence posts and rails
  • Lawn furniture and decks.
  • Playground equipment.
  • Garden/landscape timbers.
  • Log homes
  • Railroad Ties

Typical preservatives include:

  • chromated arsenicals (copper/chromium and/or arsenic);
  • pentachlorophenol (PCP);
  • creosote
  • as well other newer preservatives (ACQ, Borates, Copper Azole, Copper Naphthalene, etc.)

Under federal (RCRA) hazardous waste regulations, as long as levels of metals or pesticides do not exceed TCLP thresholds for metals or pesticides in 40 CFR 261.24, then disposal of TWW is not regulated.  California regulations are more stringent than federal standards and many treated wood products are considered hazardous waste under California regulations when disposed of.  Specifically, California defines “treated wood waste” (TWW) as:

  1. Waste wood products treated with a preservative regulated under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) with no other hazardous waste characteristics, and
  2. Not subject to regulation under the federal Resource Conservation and Recovery Act (RCRA).

Disposal of TWW in California (until 12/31/2021)

California regulations require TWW to be managed as non-RCRA hazardous waste, however California Helath and Safety Code  (CA HSC 25150.7)  established “alternative management standards” (AMS) for TWW found in Title 22 of the California Code of Regulations, Sections 67386.1 to 67386.12 (22 CCR 67386.1 – 673286.12).   Among other requirements, the “alternative” management allowed disposal in lined landfills that are not permitted for hazardous waste, as long as the landfill permit allows them to accept TWW.

Currently most TWW is sent to non-hazardous waste landfills under these “alternative” methods, however CA HSC 25150.7 (and associated regulations) expire on December 31, 2021.  After that date, TWW must be managed as non-RCRA hazardous waste.

Utility Exemption

There is an exemption for TWW generated by utilities.  As authorized in CA HSC 25143.3.5 TWW from utilities , including poles, crossarms, pilings, fence posts, lumber, support timbers, flume lumber, and cooling tower lumber can still be sent to landfills as long as the wood waste does not need to be managed as RCRA hazardous waste and the landfill meets certain requirements and is permitted to accept the TWW

Disposal of TWW in California (After 12/31/2021)

Beginning January 1, 2021, TWW must be managed as non-RCRA hazardous waste.

  • Since the definition of TWW includes all wood wastes treated with FIFRA-regulated preservatives (without any thresholds or other criteria), there is not even the option to conduct TTLC/STLC and/or aquatic toxicity to show this was does not exhibit characteristic toxicity

After the provisions “alternative management” of TWW expire on 12/31/2021, landfill disposal outside of hazardous waste landfills is no longer authorized and TWW must be accumulated, stored, managed, transported and disposed of as non-RCRA hazardous waste at a hazardous waste landfill permitted for this type of waste.

Do you have Treated Wood Waste to dispose of?  Do you have any other hazardous waste questions?  Let us know how we can help – [email protected]


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