Tire Derived Aggregate for Landfill Infrastructure

Background

According to the USDOT, “approximately 280 million tires are discarded each year by American motorists, approximately one tire for every person in the United States. Around 30 million of these tires are retreaded or reused, leaving roughly 250 million scrap tires to be managed annually. Besides the need to manage these scrap tires, it has been estimated that there may be as many as 2 to 3 billion tires that have accumulated over the years and are contained in numerous stockpiles.^”

Shredding tires to produce tire derived aggregate (TDA) material for civil infrastructure has been documented throughout the country. Tire derived aggregate as an aggregate alternate is used beneficially in civil engineering applications and within landfills across the United States in numerous applications. Multiple studies have assessed the material properties and design considerations of tire derived aggregate. Two-inch by 2-inch nominally sized tire derived aggregate results in an aggregate material similar to 1.5-inch stone aggregate. Typical applications for tire derived aggregate on solid waste landfills include use as cover drainage systems, leachate collection and drainage systems, leachate recirculation pipe bedding, and landfill gas collection pipe bedding.

Approach

In 2022, Brown County Port & Resource Recovery Department, a long-term partner with Foth, took in approximately 600 tons of tires at its collection areas. Wisconsin’s Recycling Law passed in 1990 bans waste tires from being disposed of in Wisconsin landfills, so businesses and municipalities must source alternate disposal, recycling or other diversion markets for tires. The County’s existing tire recycling vendor picked up and transported the tires 107 miles to its tire processing facility. With a commitment to waste reduction and reuse, the County issued a Request for Proposals to tire recyclers with the intent to use tire derived aggregate instead of natural stone aggregate for the pipe bedding for horizontal gas extraction wells and leachate recirculation trenches. Badger Materials Recycling, LLC (Badger), a tire recycling vendor 127 miles away, was awarded the contract.

It was estimated that approximately 3,200 tons of coarse aggregate stone was needed for a landfill infrastructure pipe bedding project. Due to the material properties of the tire, a substantially reduced tonnage of tire derived aggregate (TDA) was needed as an alternate construction material.  Badger proposed transporting the TDA to the landfill at no charge to the County, therefore, the County could obtain an estimated 1,200 tons of beneficial use tire derived aggregate at no cost. Due to the Wisconsin ban, a Plan Modification was required from the Wisconsin DNR for beneficial use of the tire derived aggregate. Foth submitted the request on behalf of the County and it was approved. The use of chipped tires was estimated to save the County over $50,000 in material and transportation costs.