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Dakota County – Lake Byllesby Dam

Boldt was tasked with upgrading the century-old powerhouse that sits on the end of a 3.5-mile long, 1,432-acre lake. The primary project goal was to preserve and upgrade the clean energy generation capability for at least another 50 years.

Project site improvements included replacing the 20- to 40-year old stop logs and interior ventilation system, replacing electrical switchgear; upgrading the powerhouse by replacing the century-old original head gates, draft tubes and overhead crane rails; and installing two new double-regulated, 2.25 MW Z-Turbines (Saxo-Type) and generators. The upgraded generating units double the output, are more efficient and match site head and flow conditions. 

Ayres Associates used 3-D scans of the site with BIM programs. These plans helped set the foundations that would eventually hold the turbines. Specialty equipment also was needed to set two, 121,000-pound generators that will supply power to the surrounding area.  

Client

Dakota County

Location
Cannon Falls, Minnesota
Architect/Engineer

Ayres Associates / Stantec

Boldt Role
General Contractor
Project Type
Renovation / Equipment Installation

MARKET
Renewable Energy

Project Highlights

  • Preserve and upgrade the clean energy generation capability of a 100-year old Ambursen buttress dam and powerhouse. For at least another 50 years.
  • Approximately 7,600 cubic yards of CIP concrete, 400 tons of rebar and 180 tons of structural steel. 
  • Project is 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. Original construction was in 1910.