Wood stave penstocks being replaced at 17.2-MW Grandfather Falls hydropower project in Wisconsin

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Wisconsin Public Service (WPS) utility began work modernizing penstocks at its 17.2-MW Grandfather Falls hydropower facility on the Wisconsin River in Lincoln County, Wis., this week as part of relicensing the facility, according to a company press release.

Work at the 79-year-old plant to replace two wood stave penstocks and install steel penstocks is part of relicensing requirements from the Federal Energy Regulatory Commission (FERC) and the Public Service Commission of Wisconsin.

The cost to replace the penstocks was not specifically stated in the utility’s announcement, but WPS said it expects the project license will be renewed in April 2018 using FERC’s Integrated Licensing Process (ILP), which should cost about US$600,000.

The current penstocks have been in operation for 43 years, according to WPS, and are no longer operating efficiently, resulting in decreased power output from the facility.

In March 2016, WPS submitted an application to FERC seeking a 30-year extension of its license for the project and its operation.

WPS began FERC’s ILP process in 2012. The ILP is intended to streamline FERC’s licensing process by providing a predictable, efficient and timely licensing process that continues to ensure adequate resource protections and should take about 7.5 years, according to WPS.

A multi-year license extension effort began in 2008 when WPS began its informal review process by reaching out to groups of stakeholders with an interest in Grandfather Falls and its operation.

The utility said new steel penstocks have a lifespan of about 80 years and will help reduce fuel costs at the project while increasing the amount of renewable energy it provides to the grid.

River flows will be diverted through the facility's bypass reach into the original channel of the Wisconsin River, and the utility says water levels and flows above the dam and below the powerhouse will not be affected by the project.

The powerhouse will be inoperable while the penstocks are being replaced. reported in February that Wisconsin Republican Gov. Scott Walker announced an additional $11 million in state funding for the reconstruction of the Little Falls Dam, located in Willow River State Park.

The Wisconsin State Legislature previously allocated $8 million for the project after inspections raised questions about the structure's integrity in early 2015. Subsequent inspections found the dam's gates were malfunctioning, that there were cracks in the concrete and that it was susceptible to seepage, leading Wisconsin's Department of Natural Resources to decide to remove it.

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