Hydro investments continue with gate replacements
July 12, 2017
A J.F. Brennan diver makes underwater concrete repairs on the intake at the Little Falls Hydro Station.
The Little Falls gate replacement project requires a crane on a barge to get components in place. When the Little Falls project is complete, the barge and crane will be moved to the Island Lake dam for another gate replacement project.
J.F. Brennan employees work on a concrete repair on the No. 2 spill capacity gate in Little Falls. Stop logs were installed on the upstream side of the gate to stop the water flow and allow access.
A large gate replacement project underway at the Little Falls Hydro Station will improve public safety and reliability at the oldest of Minnesota Power’s 11 hydro facilities.
The project includes replacement of three spill capacity gates and installation of four new head gates at the hydro station that dates to 1888.
The spill capacity gates allow operators to maintain the correct pond level behind the dam by sending water downriver, bypassing the hydro station’s generators. The new head gates will allow easier dewatering of four of the hydro station’s generating units for maintenance and repairs.
Replacing the spill capacity gates, which date from the 1920s, will improve public safety by ensuring the reliability of the system that controls water levels, both above and below the dam, at the hydro station.
Chris Rousseau, manager of renewable business operations, said the Little Falls project is part of a systemwide gate assessment done during the past year led by Dan Nordling, engineer senior and also the project manager in Little Falls.
“The assessment allows our hydro leadership team to systematically prioritize improvements on more than 220 gates, focusing on life extension and long-term reliability of those assets,” he said.
Nordling is being assisted in Little Falls by Jeff Meyer, lead maintenance journeyworker; Lance Yoki, designer; Mark Kayser, engineer III; and Andy Remus, engineer senior. Mike Chambers, production coordinator, helped predict river flows to ensure the safety of crews on the site. J.F. Brennan is the marine contractor for the project, supplying the barge, crane and divers. New gates were supplied by vendors in Two Harbors, Minnesota, and New York, and fabricated specifically for the Little Falls dam. Finish welding and coating on the head gates is being completed by Hydro Maintenance staff in Little Falls.
Rousseau said the city of Little Falls has helped support the project by working closely with J.F. Brennan and MP staff to identify areas on shore for staging as well as providing a partial road closure to improve safety and efficiency during portions of the project.
In addition to the Little Falls project, gates will be replaced at the Island Lake Dam later this summer. J.F. Brennan is the contractor on that project as well, and will move the barge and crane from Little Falls to Island Lake in late July or early August when the Little Falls project is complete. Head gates also were replaced at the Scanlon Hydro Station in 2016, and head gates will be replaced at the Knife Falls Hydro Station in the fall.
“These are all done with public safety, environmental priorities and overall reliability in mind,” Rousseau said.
