Safer Products

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Treated Wood Waste (TWW)

What is Treated Wood Waste?


TWW 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, to name a few, are all examples of chemically treated wood.

Note: The statute (HSC 25150.7) and regulations (22 CCR 67386.1 et seq.) that allow treated wood waste to be handled with alternative management standards are due to expire after December 31, 2020. After that date, all hazardous treated wood waste (not exempted by HSC 25143.1.5 as utility generated) managed in California will have to be stored and manifested as hazardous waste and transported to class I hazardous waste landfills for disposal.

Is Treated Wood Waste Toxic?

TWW contains hazardous chemicals that pose a risk to human health and the environment. Arsenic, chromium, copper, creosote, and pentachlorophenol are among the chemicals used to preserve wood and are known to be toxic or carcinogenic. Harmful exposure to these chemicals may result from touching, inhaling or ingesting TWW particulate (e.g., sawdust and smoke).

Treated Wood Waste Report

DTSC has completed an extensive analysis of TWW pursuant to Senate Bill 162 (Galgiani, Chapter 351, Statutes of 2015).  SB 162 required DTSC to prepare a comprehensive report on rates of compliance with the Alternative Management Standards (AMS) for TWW. To meet this requirement, DTSC conducted 126 compliance inspections of TWW generators and disposal facilities in California. In addition, responses to TWW surveys from Household Hazardous Waste Collection Facilities (HHWCF), Certified Unified Program Agencies (CUPA), Solid Waste Transfer Stations and Load Check Program Facilities (SW Facility) were evaluated. DTSC’s evaluation and conclusions on rates of compliance with the AMS for TWW are discussed in this report.  To download the report, click on the link below. 

Report: California Department of Toxic Substances Control Treated Wood Waste Report, March 2019

Other Documents

Report: California Department of Toxic Substances Control Treated Wood Waste Report, June 2011