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OPG’s Waba Dam Renewal Project completed ahead of schedule

In eastern Ontario, a sprawling earth dam supporting OPG’s Arnprior Generating Station (GS) just west of Ottawa has been successfully renewed to ensure continued operation and public safety.

The Waba Dam Renewal Project involved raising and reinforcing the crest of the 1,219-metre-long earth dam that supports OPG's Arnprior Generating Station.
The Waba Dam Renewal Project involved raising and reinforcing the crest of the 1,219-metre-long earth dam that supports OPG's Arnprior Generating Station. (Photo courtesy Hatch)

The Waba Dam Renewal Project, which got underway in August, wrapped up ahead of schedule and under budget in November. The dam safety initiative involved raising and reinforcing the crest of the 1,219-metre-long dam. A culvert was also replaced in a small area alongside the nearby Ottawa Valley Rail Trail.

The 15-metre-tall earth dam was originally built to support the reservoir at Arnprior GS, which went into service in 1976. Over the years, the dam had settled due to normally expected ground compression.

The renewed Waba Dam is expected to provide 50 more years of safe operation before its crest will need to be raised again.

“This project involved world experts in dam safety as well as an independent panel, which were a huge benefit. It was a large collaborative effort, from OPG’s engineers to our construction partners,” said Project Leader Amy Cameron.

Cameron attributed a big chunk of the project’s success to the performance of OPG’s partners, which included Hatch, who was responsible for engineering and design, and Pennecon, OPG’s construction contractor.

The renewed Waba Dam is expected to provide 50 more years of safe operation.
The renewed Waba Dam is expected to provide 50 more years of safe operation.

Much of the work involved removing soil from the site and adding new rock material and clay. New instrumentation was also installed at the dam to better monitor its performance and condition in the future.

During construction, the work crew also uncovered an old weir. The structure was originally built to help monitor any water flow from the dam, but it had become obscured over the years by aquatic vegetation. The area around the weir was regraded and it will now be reincorporated into operations.

“We really couldn’t have asked for better, more collaborative partners on this project,” Cameron said. “Good relationships and trust went a long way to making sure this dam safety project was a success.”