Recycled Tire Engineered Aggregate (R.-T.E.A.) was the preferred solution to fix a stretch of residential street last year in Grand Rapids, MN, according to Tom Pagel, office manager, RCM Associates, Grand Rapids. The paved street, originally built over a deep peat swamp, had settled four feet in some areas. 

RCM reconstructed three blocks of the street in the fall of 1997 using tire chips as fill over the soft soil. Now, a year later, R-T.E.A. is still performing and has survived a Minnesota winter. RCM continues to monitor the road to watch for signs of settlement or cracking. "This project is well documented," Pagel said. Based on his experience with R.-T.E.A., he believes they would use tires again. 

In the beginning of the project, however, there was some concern. It was a learning experience for RCM and the city. The learning process included giving the tire chips time to settle after compacting them. Another issue was finding tire chips that met RCM's size specifications. First State Tire Recycling, the Minnesota supplier of tire chips for the project, addressed this concern with new equipment that increased their control over the size and quality of the chips. 

Monte Niemi, C.E.O. of First State Tire Recycling said that R.-T.E.A.'s lighter weight - approximately 550 pounds per cubic yard compared to 2,800 pounds per cubic yard for gravel fill - made it an ideal solution in the Grand Rapids project. 

In addition to working well in wetlands and over other marginal soils, tire chips are also often the best engineering solution in terms of road settlement for any roadbed application, Niemi said. And, as in the Grand Rapids project, lightweight tire-fill material is increasingly outpacing other alternatives when it comes to cost. 

Mucky Mess 

County Road 11 in rural Mille Lacs County, Minnesota sat on top of 30 feet of muck. It sank. Time and time again. Attempts to add material on top of the couple-hundred-foot-long section of paved road always failed, according to Assistant County Engineer Dean Peterson. The weight of the new materials caused the road to ooze out into the swamp, he said. Imagine a warm marshmallow in a s'more sandwich. 

Then about a year ago, the county decided to try lightweight tire chips. Eighty feet of earth were excavated from the center of the road. A compacted four-foot layer of tire chips was placed on the road bed. Geo-fabric was placed on top of the tire chips, and two to three feet of earth were placed on top of the fabric. The oozing stopped. The road is working. Peterson reports the county is really satisfied with tire chips.