Could glass fragments lead to better roads
PENNOCK -- Beer and wine bottles collected from Stearns, Meeker and Chippewa counties bars are now lining the streets of Pennock. Actually, the green and brown bottles are crushed and mixed with gravel to make the road bed for the streets being b...
PENNOCK -- Beer and wine bottles collected from Stearns, Meeker and Chippewa counties bars are now lining the streets of Pennock.
Actually, the green and brown bottles are crushed and mixed with gravel to make the road bed for the streets being built in Pennock's new residential development.
The streets, and the glass, will eventually be covered with asphalt.
The test case in Pennock could help resolve problems for contractors who need quality road building material and local garbage haulers who need an affordable alternative for recycling glass.
The end result is a better aggregate product and a better road, according to Gene Isakson, who pioneered the technique in the early 1990s in Sibley County.
Pennock Mayor Kevin Crowley said the City Council had no problem agreeing to the proposed road experiment. There was "no reason" not to participate, he said.
Dean Helstrom, the city's engineer from Bolton & Menk, said he sees no problem with using a 10 percent blend of crushed glass and aggregate in the road base. "It's a good idea," he said.
That's what Chad Monson from Monson Excavating of Willmar, thought when Don Williamson contacted him this summer about cooperating on a joint venture.
Williamson, who works for West Central Sanitation, had collected bottles from bars through a recycling program, but he couldn't get rid of the bottles.
Anchor Glass Container Corporation in Shakopee pays between up to $5 a ton for post-consumer brown and green glass. The Minnesota plant doesn't make brown and green containers and has little need for purchasing bottles, said Anchor employee Kyle Fiebelkorn. By contrast, the market for clear glass in Minnesota is very strong, with Anchor paying $65 a ton for post-consumer containers that's made into new containers, he said.
Paying $250 to transport the mixed brown and green glass to Shakopee, and then not getting paid for the product, got Williamson looking for an alternative recycling option.
Monson, meanwhile, was having a hard time getting some of his gravel to meet the grade that's necessary for roads.
Williamson, who had previous experience with mixing gravel and crushed glass, said the problems he and Monson shared was solved by working together.
Williamson now brings brown and green bottles to Monson's gravel pit. Monson takes a load of bottles and dumps it together with gravel into a grinder that crushes and smoothes the small pieces of glass and mixes it with the aggregate.
The process gets rids of the glass and brings poorer-quality aggregate up to the proper standard.
Mixing one part crushed glass with 10 parts of gravel is a method that's approved by the Minnesota Department of Transportation.
Mixing crushed glass with aggregate is called class seven and has the same standards as the traditional class five aggregate that's used for roads, according to information from the Minnesota Office of Environmental Assistance.
Monson said incorporating crushed glass with aggregate won't make a huge impact on the road construction industry but it will help extend the life of existing gravel mines, which is a benefit to the county. Even if Williamson provided all the glass he collects in a year, it would provide enough aggregate amendment to build about a half-mile of eight-inch thick road base, said Monson.
Isakson, who had been serving as Sibley County's solid waste officer and highway engineer, experimented with the 10 percent crushed glass aggregate blend on projects there in 1992.
"I never had any bad results with it," said Isakson, who is now retired but offers advice on using reclaimed glass as aggregate. "I never saw anything negative about it. It was all positive."
He said he was surprised and disappointed at the time that other county highway engineers didn't think the simple technique was worth their time and the practice "never really caught on."