September 2021* 

What is Treated Wood?

Treated wood is wood that has gone through a treatment process with chemical preservatives to protect it against pests and environmental conditions. Typically, treated wood is used in exterior applications where ground or water contact is likely.

• What qualifies as treated wood?

• • Treated wood means wood that has been treated with a chemical preservative for purposes of protecting the wood against attacks from insects, microorganisms, fungi, and other environmental conditions that can lead to decay of the wood, and the chemical preservative is registered pursuant to the Federal Insecticide, Fungicide, and Rodenticide Act (7 U.S.C. Sec. 136 et seq.). These preservatives often include one or more of the following constituents: arsenic, chromium, copper, pentachlorophenol, and creosote.

• What doesn’t qualify as treated wood?

• • Natural wood with no chemical preservatives.
  • Natural wood that is painted or has a surface finish such as lacquer, shellac, polyurethane and varnish.

What are the different types of Treated Wood?

There are two main groups of treated wood preservatives, water-based and oil-based. Wood treated with water-based preservatives are widely used and are commonly utilized in residential, commercial, marine, agricultural, recreational, and industrial applications. Wood treated with oil-based preservatives is primarily used for industrial applications such as utility poles, piling, posts, and railroad ties.

• What are some chemicals that are commonly used to treat wood?

• • Water-Based Preservatives
    • Acid Copper Chromate (ACC)
    • Alkaline Copper Quaternary (ACQ)
    • Copper Azole (CA)
    • Chromate Copper Arsenate (CCA)
    • Copper-HDO
  • Oil-Based Preservatives
    • Copper Naphthenate
    • Creosote
    • Pentachlorophenol (PCP)

• How are the treatment chemicals commonly applied to the wood?

• • Pressure Treatment
  • Brief Dipping
  • Cold Soaking and Steeping
  • Diffusion

• What is treated wood commonly used for?

• • Exterior applications
  • Applications where the wood will be in direct contact with soil or water
  • Applications where long life is important
  • Utility industry – electric, gas, or telephone service (see HSC 25143.1.5)

• What are some wood species that are commonly treated?

• • Hem-Fir and Douglas-Fir
  • Pines (e.g. Southern Yellow Pine, Red Pine, Ponderosa Pine)
  • Spruce

Figure 1: Pressure treated wood showing indentations from treatment.

Is my Wood Treated and which type do I have?

Treated wood can often be visually distinguished by its appearance. There are several signs to look out for when determining if a piece of wood has been treated or not.

What are some things to look for when determining if wood is treated or not?

• • Treated wood end tag
  • Wood manufacturer stamp codes
  • Indentations on the surface of the wood (as seen in the photo above)
  • When cut, staining is visible around the perimeter only
  • Discoloration (e.g. green or dark brown appearance)
  • Odor

    Treated wood may have an end tag that looks like the figure below.

Figure 2: An example of a TWW label. Photo credit: National Pesticide Information Center.

The end tag should have information about the preservative used as well as information about proper use sites (e.g. indoors, outdoors, in water, ground, above ground).

Why is Treated Wood Waste potentially Hazardous?

TWW has the potential to be a hazardous waste if it contains elevated levels of one or more of the following constituents: arsenic, chromium, copper, pentachlorophenol, and creosote. If TWW is not properly disposed of, the chemicals it contains can contaminate soil, surface water, and groundwater. This poses a risk to human health and the environment. TWW may exceed California hazardous waste thresholds for non-RCRA waste; studies have shown that TWW is less likely to exceed U.S. EPA hazardous waste thresholds for RCRA waste. In California, TWW that is a hazardous waste is identified with state hazardous waste code 614. Analysis of representative samples of treated wood has shown that it has the potential to exhibit a hazardous waste characteristic of toxicity under California state standards. Specifically, samples of treated wood may exceed the Total Threshold Limit Concentration (TTLC) values (Cal. Code Regs., tit. 22, § 66261.24 (a)(2)(A).) for metals and may exceed the Soluble Threshold Limit Concentration (STLC) values for metals when subjected to the Waste Extraction Test (WET). Samples of treated wood may also exceed acute aquatic toxicity limits (Cal. Code Regs., tit. 22, § 66261.24(a)(6).).

What are the Hazardous Waste/Alternative Management Standards (AMS)?

The AMS (Alternative Management Standards) are statutes (HSC 25230 – 25230.18) established by Assembly Bill 332, that allows handling non-RCRA hazardous TWW in accordance with a set of alternative management standards in lieu of the requirements for hazardous waste pursuant to Health and Safety Code, division 20, chapter 6.5, articles 6, 6.5, and 9 and California Code of Regulations, title 22, division 4.5, chapters 12, 13, 14, 15, 16, 18, and 20. In summary, the AMS lessen storage requirements, extend accumulation periods, allow shipments without a hazardous waste manifest and a hazardous waste hauler, and allow disposal at specific non-hazardous waste landfills. The AMS simplify and facilitate the safe and economical disposal of TWW.

What are the Handling and Disposal Requirements for TWW?

The AMS, which went into effect on August 31, 2021, are intended to ease regulatory burdens. Although hazardous waste generators are required to properly classify their waste through knowledge or laboratory analysis, generators of TWW can presume their TWW is hazardous waste and avoid expensive laboratory testing. Generators can then manage their waste in accordance with the AMS, including disposal at certain non-hazardous waste landfills. Upon acceptance at these certain landfills, the TWW, at that point, becomes non-hazardous waste pursuant to Health and Safety Code section 25230.16. Specific generator requirements for households, small business, and all others are presented in the following sections:

Households

Households typically generate TWW when a fence or deck is replaced. Under AMS, households must abide by the following conditions:

1. Do not burn the TWW.
2. Do not remove or destroy any marking identifying the wood as treated wood.
3. Keep TWW segregated from other materials.
4. Store less than 1,000 pounds of TWW for no more than 30 days following its removal from use.
5. Transport TWW to an authorized TWW facility. If the TWW is going to a Household Hazardous Waste (HHW) Collection Center, call and confirm the acceptance of TWW (not all HHW Collection Centers handle treated wood waste or can only collect limited amounts).
6. Identify TWW to TWW facility personnel.

It is important to note that the AMS also prohibit TWW from being burned, chipped, ground, or mulched. TWW stored for more than 30 days would invoke additional requirements on households that apply to businesses.

Businesses Generating TWW Incidental to the Normal Course of Business

Incidental generation occurs when a business generates TWW as a result of activities not associated with the business’s core operation. For example, a retail store, a doctor’s office, or an auto body repair shop might generate TWW when repairing or replacing signage or fencing at their place of business. This TWW is considered “incidentally generated” because these businesses are not routinely involved in construction, demolition, or other activities that involve treated wood. Under AMS, businesses that “incidentally” generate TWW can generally comply with handling and disposal requirements by abiding by the following conditions:

Figure 3: An example of a TWW accumulation label.

1. Do not burn the TWW.
2. Do not remove or destroy any marking identifying the wood as treated wood.
3. Keeping TWW segregated from other materials.
4. Labeling all TWW bundle/shipments with the following information:
5. Storing no more than 1,000 pounds of TWW for no longer than 30 days. Incidental generators who store TWW for more than 30 days are subject to the additional requirements for businesses that are routine generators of TWW.
6. Transporting TWW to an authorized TWW facility.
7. Identifying TWW to TWW facility personnel.

Businesses Generating TWW during the Normal Course of Business

Businesses that generate, handle, or accumulate more than 1,000 pounds of TWW in 30 days engaged in activities expected to routinely generate or handle TWW, such as, construction/demolition contractors, and business and homeowners generating large quantities (i.e., accumulating more than 1,000 pounds in 30 days) must meet the requirements listed below. In complying with the TWW AMS, these businesses will minimize their liability concerns and eliminate possible future cleanup cost associated with mismanagement of TWW. You must abide by the following conditions:

1. Do not burn TWW. It is illegal to burn TWW without a hazardous waste permit. (HSC 25230.4. (a) (1)).
2. Keep TWW from mixing with other waste. (HSC 25230.4. (a) (3)).
3. Do not remove or destroy any marking identifying the wood as treated wood. (HSC 25230.4. (b)).
4. Reuse of removed TWW must be onsite and in compliance with the Federal Insecticide, Fungicide, and Rodenticide Act (7 U.S.C. Sec. 136 et seq.). (HSC 25230.4. (c)).
5. Treated wood waste shall be maintained in a manner that prevents unauthorized access and minimizes release to the environment. (HSC 25230.6. (a) (1)).
6. Prevent unauthorized access to TWW with a physical barrier or visual control. (HSC 25230.6. (a) (2)).
7. Store TWW off the ground by placing it on blocks, on concrete surfaces, or in containers. (HSC 25230.6. (b)).
8. Cover TWW to protect from precipitation. (HSC 25230.6. (b) (1) (B)).
9. Do not store TWW beyond the allowed limits:
   • Container meeting all statutory requirements – 1 year (HSC 25230.6. (b) (2))
   • Storage building meeting all statutory requirements – 1 year (HSC 25230.6. (b) (3))
   • Containment surface meeting all statutory requirements – 180 days (HSC 25230.6. (b) (4))
10. Get prior confirmation that the solid waste facility or hazardous waste facility will accept TWW shipment. Not all facilities accept TWW, so check with the facility before transporting to ensure that their load will not be rejected. (HSC 25230.7(b)).
11. Label all TWW bundle/shipments with the following information. (HSC 25230.5 (b)).
    

    Figure 4: An example of a TWW accumulation label.

    Keep records for at least three years from date of shipment or receipt to demonstrate that TWW was properly managed. Records should include: (1) name and address of the TWW facility to which the TWW was sent; (2) estimated weight of TWW, or the weight of the TWW as measured by the receiving TWW facility; and (3) date of the shipment of TWW. (HSC 25230.5 (a) and (e)(1)).
12. Notify DTSC within 30 days if generating more than 10,000 pounds of TWW per calendar year. See the listings at the end of this fact sheet for the online notification web site. The following information must be submitted:
    1. Name and mailing address;
    2. Identification Number;
    3. Name and telephone number of the TWW contact person;
    4. Address or physical location of the TWW management activities;
    5. Date exceeding the 10,000 pound limit; and
    6. A notification on our online form indicating that the business is generating more than 10,000 pounds of TWW per calendar year. An Identification Number can be obtained on our website or by calling 1-800-618-6942. (HSC 25230.9)
13. Arrange for shipment to a TWW facility. Disposal is allowed at a hazardous waste landfill or a qualified solid waste landfill. See the listings at the end of the fact sheet for information on facilities that have been authorized to accept TWW. Contact the TWW facility to obtain costs as they may be adjusted based upon volume. (HSC 25230.11).
14. Train employees involved in TWW handling and keep the training records for three years. The training shall include applicable requirements of Cal/OSHA and regulations relating to hazardous waste, methods for identifying and segregating TWW, safe handling practices, requirements of AMS; and proper disposal methods. (HSC 25230.12).

Frequently Asked Questions (FAQs)

More Information and Recommended Disposal Sites.

• Link to Waterboard Approved Treated Wood Waste Landfills
• Transfer Facilities that accept treated wood waste
• Transporters for Treated Wood Waste to Disposal Facilities
• Western Wood Preservers website (WWPI)
• Treated Wood Waste Disposal Information – Maintained by WWPI
• San Francisco Bay Area Treated Wood Waste Disposal Information

If you would like to have your company added to the listings above or for more information and questions about TWW please email us at the following email address:

Email: tww_help@dtsc.ca.gov

For all other information, please contact the DTSC Office nearest you. You can also contact our Regulatory Assistance Officers at:

Toll-Free in CA: 800-728-6942 or 800 72-TOXIC
Outside CA: 916-324-2439
Email: RAO@dtsc.ca.gov

For a list of all DTSC offices, go to our Office Address and Phone Numbers webpage.

*Disclaimer

This fact sheet does not replace or supersede relevant statutes and regulations. The information contained in this fact sheet is based upon the statutes and regulations in effect as of the date of the fact sheet. Interested parties should keep apprised of subsequent changes to relevant statutes and regulations.