Twin Falls powerhouse completion expected this summer

We expect to begin commercial operation of the new powerhouse at the aging Twin Falls hydro plant this summer. The plant borders Wisconsin and the Upper Peninsula of Michigan on the Menominee River.

Built in 1912, the dam is licensed to operate to 2040. The powerhouse was built at the same time, but its condition is such that it won't be able to operate for the license duration. Various repairs and upgrades to the dam and spillway structures have been completed since the mid-1960s, and now the powerhouse is being addressed.

The new powerhouse is being built on the Wisconsin side of the Menominee River to replace the current one on the Michigan side. The project also includes additional spillway capacity to meet current Federal Energy Regulatory Commission (FERC) safety standards.

Building on the opposite side of the river allows the existing plant to continue generating electricity during the time the new powerhouse is be built.

Maintaining the current powerhouse during construction also allows water passage during winter. Although spillway gates can freeze in the last position set during the winter, water passing through the powerhouse turbines in winter is adjusted to comply with FERC license requirements. If the existing powerhouse had been removed to make way for new construction, we would have been unable to manage the river through the powerhouse during the two winter seasons of construction.

New powerhouse construction required multiple approvals, including:

• License amendment issued by FERC. 
• Certificate of Authority from the Public Service Commission of Wisconsin. 
• Permits from Wisconsin Department of Natural Resources, Michigan Department of Environmental Quality and U.S. Army Corps of Engineers. 
• Consultation with state historic preservation groups and Native American tribes. 

After obtaining the required amendments and permits, powerhouse construction began in 2014. The old powerhouse will be taken down in the summer of 2017.

Drone view of Twin Falls construction site