Wisconsin Electric Power Co. told the Public Service of Wisconsin in an Oct. 7 quarterly project update that it is making progress on and is aiming for a 2016 completion for its Twin Falls Hydroelectric Project in the Town of Florence, Florence County, Wisconsin, and the Town of Breitung, Dickinson County, Michigan.
In May 2013, the commission approved this project. Construction as of the end of the third quarter is 59% complete. Excavation of the powerhouse intake, powerhouse and Wisconsin spillway are complete. Approximately 36,800 cubic yards have been excavated of the planned 37,500 cubic yards. Concrete placement in powerhouse intake, powerhouse and Wisconsin spillway is in progress. Approximately 9,500 cubic yards of concrete have been placed out of a planned 14,500 cubic yards.
Engineering is 85% complete, 78% complete when resident engineer is included. The final design will be completed in three phases:
- Phase 1 which covers the upgrades to the access road, upstream and downstream cofferdam construction for new powerhouse, and excavation for new powerhouse (Engineering Complete)
- Phase 2 which covers design of the new powerhouse and Wisconsin Spillway. This design package was approved by the Federal Regulatory Commission (Engineering Complete).
- Phase 3 which covers the design of the Michigan Closure Dam and demolition of the existing powerhouse (Engineering underway).
Black & Veatch is the project’s Engineer of Record. At this point, 15 of 16 planned procurements are under contract. The remaining contract (fire water pump) will be awarded this year. Twelve contracts are complete and equipment has been delivered. Manufacturing under the other executed agreements is proceeding and on schedule. Commercial Operation of the new powerhouse is scheduled for summer 2016. Demolition of the existing powerhouse is to take place in 2017. Project closeout is scheduled for 2017.
In November 2012, the commission received an application from WEPCO seeking authority to construct a new hydroelectric facility at the site of its existing Twin Falls Hydroelectric Facility, located on the Menominee River at a total estimated cost of $72.3m. The Oct. 7 update shows the cost esimate still at that figure, with $40.7 million spent so far.
The Twin Falls Hydroelectric Facility, including the dam and powerhouse, was constructed and placed in service in 1912 by a WEPCO predecessor company, Peninsular Power Co. Most of the powerhouse equipment, including the turbines, were installed between 1912 and 1915, and are in relatively poor physical condition due to age and deterioration. A safety inspection report of 2010 identified conditions at the existing forebay, intake structure, and penstocks that require repairs.
After evaluating alternatives, WEPCO decided that the most cost-effective approach to address these issues is to construct a new powerhouse and remove, rather than repair, the existing powerhouse. A need for additional spillway capacity was also a factor in WEPCO’s decision to relocate the powerhouse to the Wisconsin side of the Menominee River, as this improvement would be more efficiently undertaken in conjunction with the construction of the new powerhouse, the Wisconsin commission noted.
The proposed project is expected to generate approximately 43,600 MWh per year. The total installed capacity would be increased from 6.1 MW to approximately 9 MW. The new powerhouse would contain two 4.5-MW identical Kaplan vertical-type turbines.