PORTLAND, ME (AP) A new Maine Turnpike interchange in Sabattus is being built atop the shredded remains of about 2 million tires removed from the state’s most notorious illegal tire dump.
The project is another example of how Maine, in a display of Yankee thrift, has emerged as a national leader in the use of recycled tires for civil engineering projects.
The work on the Sabattus interchange will clean almost all the remaining tires from a 40-acre landfill in Bowdoin and help the Maine Turnpike Authority save $500,000 on the $6 million project.
"What we’re trying to do here is make use of the tire tread’s beneficial properties. This is not just to get rid of tires,’ said Dana Humphrey, a University of Maine professor and a pioneer in the use of chopped up tires in construction.
The technology has been evolving for the past 15 years and is now catching on in other states, according to Humphrey, who holds the nickname "Dr. Shred.’ In 1990, 2 million tires were used in road projects nationally compared to 52 million last year, he said.
Maine generates about 1.2 million discarded tires per year. There are 270 million discarded each year nationally.
Road builders want material that meets their specifications at the best possible price. Using tires becomes more affordable because states are willing to pay money to get rid of old tires.
The Maine Department of Environmental Protection has spent more than a decade cleaning up some 15 million tires from the state’s worst illegal tire landfills. Five tire dumps in the state each had more than a million discarded tires and the Bowdoin site had as many as 8 million.
As voters approved spending $9.5 million in six different bond issues to clean up illegal tire dumps, the state sought to find some productive use for the tires.
"We were very interested in ensuring that any of the tires that we removed from the illegal tire piles were not simply disposed of and dumped into a landfill or pumped into an incinerator, if we could avoid that,’ said Paula Clark, head of the Department of Environmental Protection’s solid waste management division.
The problem is that processing tires into usable material usually costs more than the end product is worth.
A ton of tires costs about $100 to chop into shreds that then are worth $35 a ton. But because there is a cost to disposing of tires, the state’s two companies that chop up tires – Waste Management in Norrigewock and RTG in Eliot – can also charge money to haul them away. The Department of Environmental Protection is paying roughly $80 per ton to have tires hauled away.
The Maine Turnpike Authority is using RTG for the Sabattus project. The company is providing 19,000 tons of rubber, chopped to engineers’ specifications. The MTA is paying $507,000 for the product, compared to the $1 million it would have cost to use expanded shale or another lightweight fill alternative.
In recent years, the MTA used about 1 million tires from the Durham landfill for the Portland Jetport interchange and a similar amount for the Rand Road interchange near the Portland-Westbrook line.
The Maine Department of Transportation has used shredded tires at a number of road sites, including a current project in Mars Hill where the pieces are being used to insulate a roadbed to alleviate frost heaves.