Topsoil slippage is no problem for dam, corps says.
Talk about needing a face-lift.
No sooner had the U.S. Army Corps of Engineers completed a massive repair of its Fern Ridge Dam than patches along the dam's mile-long face could be seen sliding down the slope.
The slippage is topsoil, and it doesn't affect the dam's stability, said project manager Mark Dasso of the U.S. Army Corps of Engineers.
Repeat: Doesn't affect the dam's stability.
Last week, the corps celebrated a critical, $16.5 million repair of the earthen dam west of Eugene-Springfield. The corps bumped the project to top priority and did it over the summer and fall, well ahead of the normal two-year timeline.
Now, Mother Nature is getting a chance to rough up the dam's veneer.
Grass seed was spread on the dam's downriver side after the repair, but heavy rains and cooler temperatures have stopped the grass from taking root, Dasso said.
That's left this soil layer vulnerable to what the corps has termed "soil slippage." In at least five areas, it has slipped off the clay layer underneath. It's noticeable as "ripples" or "breaks" in the straw that covers the surface, Dasso said.
"It's not unusual," he added. "We got a little bit late on the seeding, and it didn't germinate."
Erosion of the soil layer doesn't affect the function of the dam, Dasso said.
The dam will be filled to normal levels. Clear Lake Road, which runs next to the dam, will stay open.
And next summer, once things dry out, the corps will reseed the slope, Dasso said.
Fern Ridge Dam's topsoil is washing away because heavy rains and cool temperatures have kept grass from rooting on the flank of the repaired dam, the Army Corps of Engineers says.
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|Title Annotation:||Government; The sliding on a slope at Fern Ridge is just topsoil and doesn't affect stability|
|Publication:||The Register-Guard (Eugene, OR)|
|Date:||Dec 7, 2005|
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