City using crushed glass for road-building

Until recently, empty bottles and jars had to be hauled hundreds of miles from Spokane to be transformed into recycled products.

Glass collected at the curb was trucked to Calgary, Alberta, and then Edmonton, where it was turned into fiberglass. When that market dried up, Spokane’s glass was shipped to Portland, where a recycling company prepared it for a train trip to California to turn it into wine bottles.

But concerns over the financial and environmental costs of shipping glass to faraway locations led the city to look for new possibilities. Now local glass is reused locally – in road construction.

Recycling companies in Spokane that handle curbside collections from the city and Waste Management began taking glass to city property in Colbert, Wash., last summer, where it was collected until crushed for roadbeds.

The city’s first project using recycled glass began over the summer in Hillyard. The city is using 1,500 tons of crushed glass in the 1.25-mile reconstruction of Market Street. The glass was combined with crushed rock to create a 9-inch-thick bed on which an 8-inch layer of asphalt is laid, said Ken Brown, the city’s principal construction engineer. Crushed glass makes up between 12 percent and 15 percent of the roadbed.

Inland Asphalt is charging the city $293,000 to build the roadbed with the glass. It estimated the glass added $30,000 to the cost.

Officials say they’re still crunching numbers to determine if the money saved on shipping will cover the increased cost of road construction. But even if it doesn’t now, they say, working with recycled glass will become cheaper as the city and contractors gain experience.

Scott Windsor, who leads the city’s solid waste department, said the program has cut glass-recycling costs because of greatly reduced transportation costs. Before, the city paid local recycling companies $45 a ton to handle glass plus as much as $30 a ton to truck it from Spokane. The $45 charge still applies, but transportation costs are perhaps just a few dollars a ton, he said.

Even before the switch, Windsor said, recycling was cheaper than paying $98 a ton to take the glass to a landfill in south-central Washington.

Spokane has an extra incentive to recycle glass: Most trash in Spokane County is burned at the Waste-to-Energy Plant. Glass doesn’t burn. Rather than creating energy that can be sold, it uses energy as it is melted. Then it ends up being sent to a landfill anyway, with the rest of the ash created at the plant.

In 2008, about 42,600 tons of glass was collected for recycling by the city, Waste Management, which does most curbside collection outside the city, and the Spokane Regional Solid Waste System.

James E. Shelby, a glass science professor at Alfred University in western New York, said the best use for used bottles is generally to recycle them into bottles. That’s because making glass bottles out of old bottles uses significantly less energy and creates less carbon dioxide than using raw materials.

But getting the glass ready to recycle often is cost-prohibitive and creates environmental concerns about fuel usage – especially for communities like Spokane that are far from companies that use recycled glass. That problem has caused many communities to abandon curbside glass recycling. Kootenai County began sending glass to a landfill in 2008.

Shelby said using glass in roadbed is a good alternative: “If it gets broken up, it acts just like sand.”

And glass carries no environmental concerns. “What comes out is pretty innocuous stuff,” Shelby said. “That kind of glass just doesn’t have any toxins.”