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2025 CONCRETE INNOVATIONS AWARD
Below the streets of downtown Minneapolis, MN is the Central City Tunnel System that collects stormwater runoff for nearly all of downtown. These stormwater tunnels are located deep into the sandstone ground 80 feet below the street surface.
A new tunnel below Washington Avenue South was constructed parallel to the existing tunnel under Chicago Avenue to increase the amount of stormwater the tunnels can handle. Portions of the existing tunnel were also refurbished. Cemstone played a key role in the project from engineering to planning and delivering complex pumping solutions.Â
The challenge for the Central City Parallel Tunnel project in Minneapolis was to design a mix for long distance pumping while minimizing shrinkage and these requirements often conflict. Long distance pumpability requires a higher paste content while minimizing shrinkage requires less paste. Balancing these opposing demands requires careful consideration of the mixture proportions. Weather variations required constant adjustments to the mix consistency for optimal ready mix performance of the walls, ceiling, doors, and even blind pours. Each pour was unique. To achieve the desired structural integrity, some areas required specialized attention to fill voids.Â
We are extremely proud of our team for successfully completing this challenging project while delivering top-quality concrete and exceptional customer service. A big thank you to the NRMCA for recognizing our efforts with the 2025 Concrete Innovations Award—what an incredible honor! Watch the video below for more behind the scenes of the project.
