Tire-Derived Aggregate (TDA)
Currently, California generates more than 40 million waste tires per year. The Department of Resources Recycling and Recovery (CalRecycle) has a goal to increase the diversion of waste tires from landfills. One way that CalRecycle hopes to achieve this goal is by promoting the use of Tire-derived aggregate (TDA) in civil engineering applications. TDA is a lightweight and highly permeable aggregate made from used scrap tires.
Since the 1980s, research efforts and extensive material testing have enabled CalRecycle to successfully partner with both state and local governments to complete projects that have demonstrated its performance and cost-effectiveness. These efforts have ultimately resulted in the creation of numerous long-term, sustainable markets for TDA. One of the most notable is the use of TDA in the expansion of the light rail systems in the both the Bay Area Rapid Transportation (BART) and the Metropolitan Transportation Agency in Southern California. In addition to diverting about 500,000 tires from our landfills, these two projects saved BART and MTA Millions of dollars. In addition, through partnerships with CalRecycle, Caltrans and numerous local agencies experienced first-hand the beneficial engineering properties and the cost savings of using TDA in their embankment fills, slope repair, retaining wall backfill, and landfill gas collection system projects. These efforts have saved local agencies substantial amounts of funds while building sustainable infrastructure projects which have diverted large amounts of waste tires from the landfills.
The Department of Resources Recycling and Recovery (CalRecycle) encourages the use of TDA in California through several programs:
- Technical Assistance. CalRecycle provides engineering and technical assistance to local jurisdictions for education, design, and construction oversight on TDA projects in California.
- Green Roads. CalRecycle's Green Roads website promotes waste tires as a valuable resource and environmentally sound solution to solve engineering problems.
CalRecycle has a TDA grant program to provide assistance to local governments to fund TDA projects.