June 24, 2011 Corps makes dam work go easier
by Bill Mardis Commonwealth Journal
Somerset —
The U.S. Army Corps of Engineers will make it easier for contractors to work in the most critical area of leak-plagued Wolf Creek Dam.
Lee Roberts, public affairs specialist for the Corps’ Nashville District, said a lower access road and higher work platform are planned to facilitate contractors’ operations at the critical spot where the earthen section wraps around the concrete monolith.
“We are waiting on these actions as we continue to draw down the lake level,” Roberts said. The lake, flushed by heavy spring rains, is falling 3 to 5 inches a day and is still about 10 feet above the optimum 680 feet above sea level. The lake has been held as close as possible to 40 feet below pool stage to ease pressure on the troubled structure and facilitate the ongoing rehabilitation project.
Roberts indicated the planned access road will be built between the electrical grid at the downriver base of the dam and tailwaters of the Cumberland River immediately below the dam. The new road apparently is necessary to bring heavy equipment up the incline to the work site.
The higher platform will make it easier for contractors to work in the extremely fragile area. This section of the work platform will be elevated from the existing platform built on the upstream side of the dam at the start of the rehabilitation project.
Drilling in the critical area, where work has been stopped for almost a year, resumed June 1. Vertical holes are being drilled to define edges of the cave and core trench along alignment of a proposed concrete barrier wall. After testing, the holes will be gravity backfilled with grout (chemically treated liquid concrete) to enable safe installation of the barrier wall.
The Corps scrapped plans to drill in Critical Area 1 through specially designed double-walled steel casings to protect the integrity of the dam in this cavern-laced area. Instead, they have decided to use existing equipment and techniques to install the permanent concrete barrier wall.
At last report, the total rehabilitation project of Wolf Creek Dam is slightly more than 50 percent complete. A permanent concrete barrier wall, longer and deeper than a similar wall inserted during the 1970s, is being built in the earthen section of the dam. The wall is created by drilling overlapping 50-inch-diameter holes filled with concrete.
Wolf Creek Dam has been plagued by seepage since the gates were closed in December 1950. The dam was classified in high risk of failure in 2005 and a $584 million rehabilitation of the structure began in 2007. Latest projections are the project will be completed in December 2013
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