Kris Lyytinen, Cass County’s assistant engineer, looked for a solution for a troubled 5.7-mile gravel road section of CSAH No. 50 linking TH 371 and 34. While the roadway has a relatively moderate traffic count of 200 ADT, it does have a high percentage of trucks versus cars. The road has a large gravel pit operation in the middle of the section that supplies the Walker, Minn., area with gravel and bituminous paving material. The road traverses rolling hills, has many curves, and the haul trucks take their toll on the gravel surface.
"We found it hard to maintain the gravel surface, with severe washboards and potholes developing, and were having to re-gravel this segment on a frequent basis," said Lyytinen.
The county first tried placing chloride on the roadway to prevent the loss of fines, save the gravel, and help control the dust. While this increased performance somewhat, the gravel still wore out in a couple of years.
“We looked for a more long-term solution. The traffic counts did not justify and the county could not afford a bituminous surface, so it was we decided to re-gravel the road with 3 in. of new gravel, stabilize the new materials with Team Laboratory Chemical Corp.'s Base One base stabilizer, and then maintain the surface with an annual treatment of calcium chloride. This was determined to be the most cost-effective treatment for this segment of roadway,” stated Lyytinen.
The process to implement the base stabilizer was completed using county forces. A water truck was used to apply the chemical and water mix, a motor grader was used to blade-mix the material and shape the roadway, and two tractors pulling pneumatic rollers compacted the material as it was placed in three lifts.
“The roadway has been performing very well, with the washboards and potholes greatly reduced, thus decreasing maintenance and labor costs. We have also eliminated two re-graveling cycles since the initial placement, saving the county $14,000 per mile, or a total of $79,800 on the 5.7-mile project. The county is very happy with the results, as well as the citizens who are located in this area and use the road on a daily basis,” concluded Lyytinen.