The Waba Dam Renewal Project involved raising and reinforcing the crest of the 1219m-long earth dam that supports OPG's Arnprior Generating Station. (Photo courtesy Hatch)

Ontario Power Generation (OPG) has announced that its Waba Dam Renewal Project has been completed ahead of schedule and under budget.

The 15m-tall Waba earth dam was originally built to support the reservoir at OPG’s Arnprior Generating Station just west of Ottawa, which went into service in 1976. Over the years, the dam had settled due to normally expected ground compression.

The renewal project involved raising and reinforcing the crest of the 1219m-long earth dam, and replacing a culvert in a small area alongside the nearby Ottawa Valley Rail Trail. The dam is now 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.

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.”

Work on the project began in August and was completed in November.

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