News Release
| Release Number: | 03-059 |
| Dated: | 5/8/2003 |
| Contact: | Heidi Y. Helwig, 503-808-4510 |
Portland, Ore.-Fern Ridge Dam on the Long Tom River is showing its age. Completed in 1941 by the U.S. Army Corps of Engineers, the dam’s internal drainage system is not functioning as designed and is showing signs of failure.
The situation at the dam has been classified as being in a “pre emergency” condition, said Mark Dasso, Corps project manager. The classification is part of a precautionary process through which Corps leadership, congressional members, emergency response agencies and appropriate federal, state and local authorities are briefed on the situation at Fern Ridge Dam.
“If something does go wrong, we’ve ensured that the right people are in the right place at the right time to react safely,” Dasso said. But for now, he said, the structure is safe, allowing the reservoir to entertain thousands of visitors through the end of the summer.
To be on the safe side, however, Corps engineers are monitoring the dam daily for signs of distress or instability that would warrant an early drawdown of the reservoir. Investigations are underway to help them decide the best course of action for repairs. While a number of repair alternatives are being discussed, to include repair work beginning as early as this fall or as late as Spring 2006, the repair of the drain system itself is nonnegotiable, said Dasso. The timing of the repairs, however, Dasso said, is dependent upon when the Corps receives requested funding for the work.
A public meeting will be held in June or July to present the latest findings, repair alternatives and timelines (a date will be announced later).
“We want people in the greater Eugene area to be informed about our plans to operate, maintain and repair the structure,” Dasso said. “We understand that the dam and reservoir are important assets to the local community.”
Until a date is set for a meeting, information about the Fern Ridge Dam situation has been posted on the Corps’ “Top Issues” web site at www.nwp.usace.army.mil.
Repairing the dam may mean taking it out of commission for at least one recreation season, Dasso said. “We understand the economic bind this could put local vendors and businesses in,” he said, “but operating a potentially unsafe structure is out of the question.” Corps engineers and scientists will work quickly on repairs so that economic impacts are minimized, he said.
The first indication of a failing drainage system came in July 2002 when project personnel reported a circular depression about 10 feet in diameter on the downstream slope of the dam. Although the depression is not directly above the main line, the Corps suspected the drain system was the likely cause when a tiny video camera inserted into one of the lateral drainpipes below the depression recorded significantly deteriorated pipes.
In February 2003, two more circular depressions were found directly above drain lines. Combined with these findings are elevated piezometer readings. Piezometers are instruments used to measure the elevation of ground water inside the dam. If the internal drainpipes were working as designed, piezometer readings in Fern Ridge Dam would be several feet lower in elevation than current readings.
Monitoring of the depressions and external drains has been increased to seven days a week, but the operation of Fern Ridge Dam and reservoir has not been affected. Dasso said, however, that he expects the failed drain system to continue to negatively affect the structure, which could eventually affect the stability of the dam.
“If we thought the stability of the dam was in question now, we would draw down the reservoir immediately,” Dasso said. “The good news is that we caught the drainage problem early in the season and devised an aggressive monitoring effort that has allowed us to operate the project normally for the 2003 recreation and irrigation season.”