Treated Wood Illegal in Garbage/Recycling & Drains Hazardous Waste Treated wood contains chemical perservatives and is hazardous. It can only be disposed of at a specially-lined landfill. Paperwork is required and fees apply. Examples of treated wood include old fence posts and decking, railroad ties, telephone poles, sill plates, landscape timbers, pilings, guardrails, and more. Contact San Mateo County Health for assistance or haul to the Buttonwillow Landfill operated by Clean Harbors. For more information about TWW, visit the California Department of Toxic Substances Control (DTSC) website. Never Burn Treated Wood Chemicals such as creosote are used when treating wood, which creates toxic ash and emissions when burned. These particles lodge in soil and groundwater and take many years to break down, so never burn wood if you think it has been treated. Take Care With Sawdust Avoid breathing in sawdust from treated wood, and do not add it to compost or scatter on the ground. Ways to Reduce Choose a Different Wood Redwood and cedar are both naturally pest-resistant. Suppliers are also starting to offer more non-toxic treated wood options. Ways to Reuse Repurpose for New Project Certain types of wood products can be reused in a variety of ways. Find out how to repurpose your wood product.