Resource Reduction: Recycled Materials

When hearing about recycling efforts, most people think about sorting their cans and bottles from their trash. Beyond home recycling — due to the number of materials generated in construction done by City crews — our Public Works Department has turned to recycled road materials. By recycling asphalt, sand, and concrete used on our streets, the City is demonstrating its commitment to lowering costs and enhancing our operational sustainability.

Concrete materials leftover from road projects throughout the City are crushed into a modified subbase. The modified subbase materials are then used to help create concrete, used to build roadways. Fines, or tiny bits of rocks, generated by this process can be used on trails. Compactable materials can be used around sewer and water repairs. “Developing alternative uses for these products reduces waste and decreases operational costs — not just for Public Works, but for other departments as well,” said Assistant Public Works Director Mike Duffy.

After roadway projects are complete, the leftover asphalt is crushed into millings, also known as ground up, recycled asphalt. These millings work well in alleyways, as shoulder material, and even on golf courses as cart paths.

Annually, nearly 3,000 tons of material collected by street sweepers are brought to the Bowling Street location for recycling. This material is put into a sifting machine to sort the trash from reusable materials. “This process has helped us reduce the number of unusable materials we send to the landfill by about 80 percent,” Duffy said.

The material screened from the trash is typically high in organic materials, which can’t be used as a structural fill, but have many other uses. Materials diverted from the landfill have been used on guardrail-removal projects to soften roadway slopes, so that a guardrail is no longer needed. The materials have also been used during stump removal, acting as a fill to reduce settling before a final topsoil application completed the restoration process. According to City records, sweeper dumps have been used to backfill nearly 8,500 stumps across the City in the year 2022, following the Derecho of 2020.

In a further effort to help reduce our carbon footprint and air pollution, the Public Works Department has reduced the amount of salt used during snow and ice events by 30 percent. This has been possible through upgrades to equipment to allow for pre-wetting of material, blending of liquids, and brine application prior to storms to prohibit the bonding of snow to the pavement. Calibration and training have also been focuses to ensure a high level of service. Because of the reduction in salt use during these events, the City has reduced the amount of salt ordered to have on hand.