Firm To Use Glass Cullet For Landfill

The pile of glass fragments at Waste Management Inc., a Seattle recycling center, reaches 30- to 40-feet high and takes up about an eighth of an acre. Weighing more than 30,000 tons, it's enough to fill a high school gymnasium.

Fibres International, a Bellevue-based recycler, has another pile of about 4,000 tons of cullet, glass fragments that can't be recycled because they're too small.

Until recently there haven't been any uses for these left-over glass fragments.

But that's changing. Seattle Solid Waste, for example, expects to save more than $20,000 by using glass cullet during work at the Kent Highlands Landfill.

A one-mile stretch of 156th Avenue Northeast in Woodinville was paved with an experimental substance in which crushed cullet was substituted in varying degrees for rocks.

Other uses are emerging, too. Eventually, new applications will make these piles smaller, earn money for recycling processors and save money for companies and government agencies in construction projects.

Glass cullet is beginning to be used as a replacement for rocks and sand on road construction projects and as a substitute for soil as fill material.

"The economics of it are very attractive," said Aaron Ostrom, a recycling planner for Seattle Solid Waste.

Government agencies are taking the lead in conducting experiments to find new uses for glass cullet, partly because they instigated the recycling curbside collection programs that have produced it.

The Kent landfill has been under construction since 1986. Recently, an impermeable plastic was placed on top of the 60-acre site. This week, more than 2,000 tons of glass cullet was put on top of that.

The cullet, which will serve as the drainage layer, eventually will be topped by soil, which then will be planted with grass. Grading to ensure proper drainage at the landfill will require another 2,000 tons of the material.

Seattle Solid Waste, which operates the landfill, paid $2.45 per ton for the cullet, a price that included hauling, said Cathy Orsi, project engineer. Cullet alone costs $1.50 a ton. Rocks and gravel would have cost $10 to $15 per ton.

Woodinville's "glassphalt" road has one section of 10 percent glass and another that's 5 percent. The year-old road will be monitored for the next 10 years, said Lou Haff, county road engineer.

Building the road cost 30 percent more than roads without glass, but most of the extra cost can be attributed to the experimental nature of this program, Haff said.

"I believe if done on a larger scale, that price would go down dramatically," he said.

Glass cullet's future use in roads is uncertain and will depend on how much of the material is available. If supplies grow, government agencies will be expected to find more uses for it, Haff said.

"Government kind of has to pave the way on that," said Greg Matheson, Fibres International vice president. "That's how something such as this gets established and accepted - developers probably aren't involved in enough work to lead the way."

Fibres' cullet pile is all green glass. Matheson said it's possible that a California company may soon buy some of the cullet to make containers.

Waste Management's pile is made up of mixed-colored glass fragments that would take too long to sort by hand. Finding uses for this mixed glass is more difficult.

"Both types will find a use," Matheson said. "It's just a matter of patience and lowering your economic expectations a little bit."

The ground, mixed-color glass provided by Fibres to the county for the Woodinville road experiment resembled coarse brown sugar. It could ultimately be offered as a substitute for beauty bark, the wood shavings used in landscaping for appearance and also to block weeds, Matheson said.

The Seattle area's other major curbside recycling collector, Rabanco, requires its customers to sort glass by colors and has only a small amount of cullet.

Another possible use for mixed-colored cullet is as the base layer under paved roads. The State Department of Transportation has used it occasionally for that for more than a year.

But the agency doesn't expect to increase its use, mostly because the processing and mixing involved takes away from the savings cullet offers over sand and gravel, said Bob Gietz, materials engineer.

Don Kneass, Northwest recycling coordinator for Waste Management, said he's been trying to develop new markets for the material for more than eight months but has found people cautious.

With government agencies leading the way, that's expected to change.

"This is one of those things where when one person does it, it makes it more acceptable and paves the way for a lot of other people," said Ostrom of Seattle Solid Waste.