Leak at Pacific Power’s Bend hydro dam to prompt repairs
Pacific Power said Monday it’s preparing to make reinforcements to its more than century-old hydroelectric 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 in early November.
Last Wednesday, a plant operator discovered more water than normal passing through an outlet that was once used to regulate river flow, utility spokesman Tom Gauntt said in a news release.
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 is affecting the company’s ability to maintain normal water levels for Mirror Pond, but poses no safety risk and does not impact the structural integrity of the dam,” the announcement said.
The work will include driving long pieces of interlocking steel sheets, known as sheet pile, into the river bed to create steel facing on the upstream side of the leaking panel and remaining sections of the 100-year-old wooden structure that have not already been reinforced.
The method was successfully used in 2008, 2009, and 2014 after similar leaks were discovered. The entire face of the dam will be reinforced with this next round of sheet pile installation.
“These reinforcements 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.
The work will begin as soon as a large construction crane can be brought into the area and all needed permits are in hand. The company currently expects the work to start around Nov. 5 and last for about four weeks.
Mirror Pond levels are currently about two feet below normal for this time of year, the utility said, and are expected to remain two to four feet below normal until the reinforcements are complete.
The work comes as the city of Bend, Bend Park and Rec District and others are working to figure out how to cover the estimated $6.7 million cost of dredging silt from the pond, last dredged in 1984. A new city council subcommittee will explore the wide range of options to come up with the funds, including a franchise fee utility ratepayers would pay.
