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Dakota County – Byllesby Dam Powerhouse

Dakota County - Byllesby Dam Powerhouse Exterior on River - Site

Originally constructed by H.M. Byllesby Company in 1910, the Byllesby Dam sits along a recreational trail and a county park. Starting in the preconstruction phase, Boldt worked with the design engineers and owner to keep some of the iconic look of the historic powerhouse while modernizing it. An additional project priority was to protect local pedestrians so they could continue to safely enjoy the outdoors throughout the construction phase of the project. Upon completion of the project, Boldt placed some of the original turbine equipment in the park for permanent display to the public.

There were many challenges during the early work portion of the project to be ready for demolition due to the age of the powerhouse and dam. Boldt and our trade partners were able to adjust planning quickly and safely to be able to continue construction activities.

With the help of the design team, Boldt recommended a revised access road location that moved the cofferdam closer to the powerhouse. This location change saved approximately 60% on material costs and labor. It also moved the cofferdam and access road away from the south spillway to save on potential rework later in the project.


Dakota County

Cannon Falls, Minnesota

Ayres & Associates / Stantec / Wenck Associates

Boldt Role
  • General Contractor
  • Design-Build
Project Type
Project Size

Renewable Energy

Project Highlights

  • Project used approximately 86,000 work hours.
  • Approximately 7,600 cubic yards of cast-in-place concrete, 400 tons of rebar and 180 tons of structural steel were needed to complete the project.
  • Project was a Chase Level 3 Project with a partnership between the contractors, AGC and MN OSHA
  • Boldt replaced the existing powerhouse and turbines, penstock and other associated equipment