Reducing street maintenance costs and eliminating potholes rank high on the City of Pipestone’s public policy agenda. So when the city needs to rebuild a street and the infrastructure below, it’s been turning to concrete.
You might say: The city is building for the future.
“We are looking at the extended life of a concrete street,” said City Administrator Jeff Jones. And in some cases, that means replacing an asphalt street with a concrete one.
That was the case with its 2017 street project in the Hill Elementary School neighborhood. In addition to new streets, the city needed to replace its deficient and/or undersized underground water, sanitary sewer and storm sewer utilities on Seventh Avenue SW, Ninth Street SW, and 11th Street SW.
City requires asphalt and concrete bids
When the city put the project out for bid, it required both asphalt and concrete bids for the pavement.
“The city wanted to see what the cost difference was, knowing the life of concrete is longer,” said City Engineer Travis Winter of Bolton & Menk. And while asphalt prices have been dropping elsewhere, Winter said, he’s seen asphalt-paving projects in the region come in at higher costs the last few years.
Pipestone, a community of about 4,300 residents, is located in southwestern Minnesota. Many cities in the region are home to ready mix plants.
Availability factors into pricing, said Dan Scotting, Buffalo Ridge Concrete Plant Manager and part owner of the company.
“Unless there is a larger, asphalt project set up by MnDOT in the region, asphalt has to be trucked up to 40 miles,”said Scotting.
“All anybody wants is an opportunity to bid and make sure cities are comparing apples to apples,” Scotting said. Factoring in the cost of maintenance over the life of the street provides an apples-to-apples comparison.
“And frankly, cities are getting better bids when they require both because there is more competition.”
Winter said that while concrete generally costs about 3/4 more on the front end, it requires little or no maintenance. So at the end of 50 years – the life expectancy of a concrete street — the cost of asphalt and concrete are about even.
MnDOT reports that the average life expectancy of their concrete pavements is 27.5 years before repair while asphalt pavements have an average life expectancy of only 15.5 years before repair.
Concrete is saving Pipestone money
Winter’s projections were about on target: For this project, paving with concrete cost about $350,000 or about 60 percent more than the asphalt bid. That’s about $30,000 more per block paved. But when the city considered the costs of maintaining the asphalt street for 50 years, the city is projecting an overall cost savings of $10,000 per block.
As Winter explained, if the city had selected the lower cost asphalt, two major maintenance projects — mill and overlays to the asphalt — would be required, adding another $40,000 per block to the initial cost.
“If I get any pushback from residents, it’s that we are building more of a street than we need,” Jones said. But once we explain the difference in what’s required to maintain an asphalt street vs. a concrete street, in both terms of work and cost, they seem to understand.
It’s a matter of education, said Jones, adding, “Once they understand, they are generally supportive.”
The project cost totaled $3.07 million, including engineering fees. Roughly 20 percent of the cost will be assessed to property owners. The city purchased bonds to finance the remaining cost.
June 2017 –November 2017
- Concrete depth: 6 inches with 6 inches of Class 5 Aggregate sub base and 6 inches of select granular borrow
- Total project length: .85 miles
- Total Concrete Placed: 3,632.5 cubic yards (CY), including concrete used for pavement, curb, gutter; another 684 CY for driveways and sidewalks
Owner: City of Pipestone
Project Lead: Travis Winter, Pipestone City Engineer of Bolton & Menk, Fairmont
Project Designers: Bolton & Menk, Fairmont, MN
Prime Contractor: Quam Construction Company, Willmar, MN
Concrete contractors: Hulstein Excavating, Edgerton, MN and Hisken Construction, Marshall, MN
Ready Mix Concrete Producer: Buffalo Ridge Concrete, Pipestone MN
Download the Pipestone Case Study.