News Release
| Release Number: | 03-205 |
| Dated: | 12/30/2003 |
| Contact: | Heidi Y. Helwig, 503-808-4510 |
Portland, Ore.-Positive results of a recent "sprinkler" test alleviated one of the two key concerns the U.S. Army Corps of Engineers has had since depressions developed on the slope of the Fern Ridge Dam in 2002 and 2003.
For the test, the Corps installed three separate sprinkler systems on the dam. One system was the study's control system: it was located on a portion of the dam that had never exhibited any unusual seepage and has no visible depressions. The second sprinkler system covered one of the depressions found in February of this year. The third system was on an area of the dam that seeps unusually large amounts of water during heavy rain.
According to the analysis performed after the investigation, water levels inside the dam should remain at safe levels even during the winter months when the dam is saturated by winter rains. Therefore, instability of the dam due to saturation is no longer a concern, said Mark Dasso, project manager for the repair work at Fern Ridge Dam on the Long Tom River.
"We still have not come to a conclusion on our other key concern, however," Dasso said. That concern is on whether or not material from deep within the dam or the foundation is being discharged as water passes through the failing drainage system, he said. "We will be completing the investigation in January and should have enough information by then to determine the extent of the problem," he said.
Until the Corps has its answer to this second concern, water regulators at Fern Ridge Dam still plan on capping the stored water in the reservoir at elevation 371 feet, 2.5 feet below full pool, Dasso said. Also, during the flood damage reduction season that continues through February, the Corps will release stored water when and if the elevation reaches 371 feet, although the reservoir is designed to store rain and runoff up to elevation 375 feet, he said.
"Once we have the remaining information on the issue of the discharge of soil, we will reassess the water restriction. We know this situation causes a great deal of inconvenience for both recreationists and businesses, but the restriction is the prudent way to ensure the safety of the 62-year-old dam and those living near it," he said.
Existing information on the condition of the dam can be found on the Corps' web site at https://www.nwp.usace.army.mil/ under "Top Issues."