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Alliant Energy – Bent Tree Wind Farm

This 60 square mile project site is located 15 miles north of Albert Lea, Minnesota, off state highway 13. Boldt was awarded the installation and grouting of 122 turbine foundations at the 200 MW Bent Tree Wind Farm. At the peak of construction, Boldt had 85 workers onsite, including subcontractors. Boldt provided construction services, supervision and equipment to construct 122 concrete foundations for Vestas V82 1.65MW wind turbines.

We were responsible for procurement and installation of the anchor bolt assembly systems, electrical grounding grid and foundation conduit. Boldt also handled the excavation and backfilling of the foundations, including soil stabilization measures using the GeoPier System.

A portable concrete batch plant was utilized to support the construction of the 540 cubic yard foundations. Boldt furnished and installed a total 4,812 tons of rebar for the project and more than 68,000 cubic yards of concrete was poured.

Client
Alliant Energy
Location
Harland, Minnesota
Architect/Engineer
Alliant Energy
Boldt Role
Self-perform Construction
Project Type
New Construction
Project Size
200MW

Project Highlights

  • At one time the area was a swamp. The native soil conditions made crane walks, excavation and backfilling extremely challenging. There was also a high level of peat which led to over excavating and backfilling with stone before construction could start.
  • A six-day-a-week schedule was established to help make up for unseasonable rain fall and two tornadoes that did considerable damage to two turbine sites. Weekly safety meetings were conducted to reinforce and refocus on working safely.
  • There was no lost time or recordable accidents for the Boldt employees.