U.S. seeks drilling for inclinometers in landslide area of 2,620-MW Chief Joseph Dam

The U.S. Army Corps of Engineers seeks bids to perform drilling to replace inclinometers monitoring what the Corps called a “massive landslide” on the left bank of 2,620-MW Chief Joseph Dam on the Columbia River in Washington. Bids are due Feb. 28.

Chief Joseph currently is undergoing refurbishment of 10 Francis turbines to increase their rated output and peak efficiency. The Corps awarded contracts in 2013 for dissolved gas and temperature monitoring and 2012 for replacement excitation systems at Chief Joseph.

“The left bank at Chief Joseph Dam has a massive landslide that has been creeping since monitoring began over 40 years ago,” the Corps’ Seattle District said. “Fourteen inclinometers were installed between 1973 and 1983, and each one within the confines of the slide has shown movement.”

The agency said the highest rate of movement is concentrated toward the toe at the southern end of the mass, nearest the dam, causing two critical inclinometers to move so much as to disable their ability to be read.

“The possibility of a catastrophic movement affecting dam safety is not known, and a comprehensive study is under way to determine if measures need to be taken to avoid disaster, or if the landslide is a non-critical issue,” the Corps said. “These two inclinometers need to be replaced for this effort.”

The Corps seeks bids to drill two 6-inch diameter holes, one 135 feet deep and another 195 feet deep, with an option for a third hole to 145 feet deep. Work is to include installation of 85-millimeter-diameter ABS plastic grooved inclinometer casing. Soil samples are to be recovered for geological characterization by a field geologist. Standard penetration tests of soil units are to be performed while drilling.

A solicitation notice may be obtained from the Federal Business Opportunities Internet site, www.fbo.gov, by entering solicitation No. W912DW14Q0014 in the “Keyword/Solicitation #” box.

Bids are due Feb. 28. For information, contact Jenny J. Scroggins, U.S. Army Corps of Engineers, Seattle District, Attn.: CENWS-CT, P.O. Box 3755, Seattle, WA 98124-3755; (1) 206-764-6696; E-mail: jennifer.j.scroggins@usace.army.mil.

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