News Release
| Release Number: | 04-188 |
| Dated: | 9/29/2004 |
| Contact: | Heidi Y. Helwig, 503-808-4510 |
Portland, Ore.--Changes at Fern Ridge Dam have piqued the U.S. Army Corps of Engineers' interest, but not alarmed them, according to Mark Dasso, the Corps' project manager for Fern Ridge Dam repairs.
The changes, Dasso said, are increased discharges of sediment through the dam's internal drain system. Nearly twice as much sediment was collected from a drain on the face of the dam identified as station 45, Dasso said. For instance, in May, June and July, the daily average of collected sediment at station 45 was nearly three-tenths of a pound. In late August and September, however, the average daily amount increased to nearly six-tenths of a pound, Dasso said. None of the other 10 drains or stations are showing any change in condition, he said.
While the extra sediment has caused some raised eyebrows, Dasso said it's too early to determine if the readings for August and September are anomalies or the beginning of an upward trend.
"We're stepping up our monitoring of the dam from monthly readings to weekly readings," he said. "We're concerned, but we're pleased to know our monitoring system is working the way it was designed. Right now, we just have to concentrate on finding out why this one drain is producing more sediment. Once we have that answer, we can focus on what to do about it."
In January, Corps engineers analyzed video footage of the dam's internal drain system with a remote video camera and deemed the dam safe. While some material from deep within or under the dam was being discharged through the drains, it wasn't enough of a discharge to warrant modified operations. Through testing, the Corps also was able to rule out any instability problems, as well.
The Corps will continue to monitor the dam with instruments that alert engineers if and when conditions change or worsen. As more information becomes available on this issue, it will be posted on the Corps' web site at https://www.nwp.usace.army.mil.