Paving the Way

At home, many people are used to recycling, whether it’s by collecting deposits when returning a can to the grocery store or bundling newspapers to be picked up at the curb. These materials make their way back into consumers’ lives in a new form: Plastic water bottles, for instance, return as fleece jackets or deck flooring. As the saying goes, "every little bit helps."

The asphalt paving industry, however, is doing more than just its little bit. It recycles more than 73 million tons of the approximately 90 million tons of asphalt pavement produced annually. According to a 2007 report from the Asphalt Pavement Alliance, the amount of asphalt recycled is more than twice the combined total for paper, glass, plastic and aluminum by tonnage. In addition, with the price of aggregate and petroleum rising, what’s good for the natural world is increasingly good for the wallet.

Recently, the Oregon Department of Transportation (ODOT) contributed to that effort as it worked to conserve the environment and taxpayer dollars. In the course of replacing two bridges on Interstate 5 near Wilsonville, Ore., and performing pavement preservation on 22 miles of the six-lane highway, the agency and contractor kept 130,000 tons of asphalt and concrete in circulation and saved more than $133,000 in landfill fees.

"This section of highway has seen an increase in passenger car traffic and wear and tear from studded snow tires," says Elizabeth Hunt, engineer and manager of ODOT’s Pavement Services. "We were able to restore the interstate proactively, removing and replacing two inches of pavement while keeping traffic moving."

The bridge replacements are part of the 10-year, $1.3 billion OTIA III State Bridge Delivery Program, in which ODOT will repair or replace hundreds of aging highway bridges, with the pavement preservation as part of ODOT’s Interstate Maintenance program.

On this project, subcontractor Staton Cos., a firm based in Eugene, Ore., demolished the bridges and separated the concrete and rebar on-site. The crew salvaged the concrete for use as backfill material on other projects and resold the rebar to a metals recycling company.

"Recycling is standard procedure on the bridge program," says Bill Relyea, project manager for Oregon Bridge Delivery Partners, ODOT’s program management firm for the bridge program. "It’s a sensible, sustainable business practice to reuse materials. In addition, the hauling distances are decreased, which saves both money and time."

As part of the standard operating procedures for paving projects, contractors hauled away the asphalt pavement removed during the bridge program project and stockpiled it for reuse as reclaimed asphalt pavement, or RAP.

The asphalt and aggregate that make up RAP are both valuable commodities. Once the asphalt is melted down, it and the reclaimed

"Although ODOT regulations don’t allow RAP in the open-graded pavement necessary for I-5, we saved money by reusing 15 percent of the asphalt initially removed from the site when we paved the ramps with dense-graded pavement," says Randy Burg, project manager from Hamilton Construction Co., the contractor on the project.

ODOT is one of many DOTs that specify interstates be repaved with open-graded asphalt—that is, porous pavement that allows water to drain—rather than RAP. In a rainy area like the Willamette Valley, through which I-5 runs, open-graded asphalt is a necessity, because it improves visibility by reducing splash and spray. Such pavement is safer for motorists and can reduce road noise.

The Asphalt Pavement Alliance notes other environmental benefits of recycled asphalt. Stockpiles of RAP do not leach into water supplies; in fact, drinking water reservoirs are often lined with asphalt. In Oregon, state fish and wildlife agencies use asphalt pavement to line fish-rearing ponds.

"ODOT works hard to make cost-effective decisions to maintain our road system in good condition. Well-maintained roads are good for everyone," Hunt says. "Smooth roads reduce fuel consumption and support heavy loads better. The longer a road lasts, the fewer raw materials we use and the less time motorists spend in traffic congestion while the roads are being rehabilitated."

For their dedication, hard work and public service, on Feb. 12 in Eugene, the team that worked on the I-5 Wilsonville-Hayesville Interchange project received an award from the Oregon Asphalt Pavement Association. ODOT will share the award with three of its contractors—OBEC Consulting Engineers, which designed the project; Hamilton; and Oregon Mainline Paving, which recycled the asphalt.

The asphalt industry has been recycling on a large scale since the 1970s, when the price of petroleum first skyrocketed. With oil breaking the $100-per-barrel mark in January 2008, RAP continues to be a highly valuable commodity, and ODOT and its contractors are doing all they can to give old pavements new life while protecting public safety. C&DR