Old tires prove to be solution for new Anoka County road

It is a mile stretch of Anoka County Road 14 where the rubber meets the road -- above and below the asphalt.

Buried below the scenic stretch between Lino Lakes and Centerville that cuts through one of the county's jewels -- the Rice Creek Chain of Lakes Regional Park Reserve area -- is a layer of about 2.6 million shredded tires, used to firm up a mucky area beneath the road.

"Traditionally, you dig 10 to 15 feet deep and you get sand," explained Doug Fischer, the county engineer in charge of the $26 million, two-year reconstruction project that was completed last week. "But, here, the peat bogs were 40 to 60 feet deep. There was no bottom to it."

In western Anoka County, this same road is known as Main Street and leads travelers to Anoka's downtown shops and the county government center and through Coon Rapids' sprawling malls. But in the eastern part of the county -- through an area including the Wargo Nature Center, George Watch Lake, Peltier Lake and Centerville Lake -- there are no car dealerships nearby. Just tires below.

By using tires shredded into four or five chunks apiece as filler, the county has employed an engineering strategy that is occasionally used, but rarely to this degree, Fischer said. Engineers will sometimes use scrap from as many as 100,000 tires, he said.

But 2.6 million?

Bogs run deep

There was also the fear that "mucking out" the bogs might be environmentally damaging to an area the county has taken great pains to preserve, Fischer said.

The project team of the county and the SRF Consulting Group worked with the Rice Creek Watershed District, the Minnesota Department of Transportation and the Minnesota Pollution Control Agency. Eight public meetings were held. Engineers spoke to Anoka County Parks system experts.

And then Fischer's team decided to spend some of the project's federal and county funding on used tires.

Using wood chips was an option that was briefly considered and has been used below the surface for other road projects. But the lightweight chips can decompose and vanish, Fischer said. So the county opted to keep 2.6 million worn tires out of landfills.

"The road's on a swamp, and swamp deposit won't support a road; it will squish down," said Jim Dvorak, the SRV vice president who served as project manager. "You have to figure a way to float the road over the top of it."

Buying used tires instead of more expensive materials may have saved the county as much as $3 million, Dvorak said. But the tires could not be placed in water, because of pollution concerns, Dvorak said.

So they were shredded, kneaded together, encapsulated in fabric and placed about 12 feet below the surface. That layer was then compressed by a 4-foot-deep layer of sand that covers the tire scraps and sits just below the asphalt.

Both Fischer and Dvorak think the project is award-worthy and say the reconstructed portion of Cty. Rd. 14 -- and a trail that runs alongside it -- blends seamlessly with the regional park and downtown Centerville, where the road again becomes Main Street. The reconstructed portion of the road is compatible with a future road construction project at the interchange of County Rd. 14 and Interstate 35E.

The only miscalculation may have been the number of tires needed. At a site in the county are four mounds of tire scraps, each about 7 feet high, 10 yards wide and 20 yards long. They are protected by a surrounding dirt fire ring.

"We had the corner on used tires in Minnesota and wanted to get them when we couldn't," Fischer said. "They won't be here long. Somebody will want them for another project."