Mirror Pond Dam repair work set to begin Tuesday
Pacific Power said Friday it is assembling equipment and materials needed to make repairs to its dam in downtown Bend to address a small leak that developed in one of the structure’s wooden panels.
The work is expected to begin next Tuesday as Mirror Pond is drawn down to allow the repairs to proceed safely. At that time, a large crane will also be assembled on site.
“We know the special place Mirror Pond has in the hearts of Bend residents,” said Matthew Chancellor, regional business manager for Pacific Power. “The necessary lowering of the pond to do this essential work will expose mudflats for about two weeks, but as soon as the repairs are done we will be able to get the pond back up to normal levels. We want to thank Bend residents for their patience during this brief period of essential work.”
The pond will be lowered about three feet below normal, about the same level reached in October 2016, when the pond was lowered at the city’s request to allow for work on a whitewater park.
On Oct. 10, a plant operator discovered more water than normal passing through an outlet that was once used to regulate river flow.
The source of the leak is a wooden panel that was installed about 25 years ago to seal the outlet, which is no longer used. The leak affected the company’s ability to maintain normal water levels for Mirror Pond, but posed no safety risk and does not impact the structural integrity of the dam.
The work involves installing long pieces of interlocking steel sheets, known as sheet pile, on the upstream side of the leaking panel and remaining sections of the 100-year-old wooden structure where sheet pile does not currently exist.
The method was successfully used in 2008, 2009, and 2014 after similar leaks were discovered. The entire face of the dam will have sheet pile after this work is complete, the utility said.
“These repairs will allow us to continue to operate the hydro project and maintain Mirror Pond levels for the community for the foreseeable future,” said Mark Sturtevant, managing director of Renewable Resources, who oversees hydro operations for PacifiCorp.
The dam is located near the Newport Avenue bridge. In addition to diverting water for the company’s hydroelectric project, the dam creates Mirror Pond by impounding the section of the Deschutes River immediately upstream.
