Getty said the concrete barrier wall being installed in the dam to stop uncontrolled seepage is about 96 percent complete. The contractor, Treviicos-Soletanche Joint Venture, “ ... has done a fantastic job.”
Work has been in Critical Area 1 since September and Getty said the contractor has been able to get three drills instead of two in the fragile section, thus advancing the schedule. Critical Area 1 is a cavern-laced section of the dam near the wraparound of the earthen section with the concrete monolith. The area initially wouldn’t accept grout and ended up delaying the remediation project about a year.
The concrete barrier wall is complete except in the critical area. The wall is formed by drilling overlapping holes 50 inches in diameter 275 feet deep from the work platform on the upstream side of the dam to about 100 feet into bedrock beneath the dam.
Getty said the entire project is about 85 percent complete but most of the remainder is site work.
The barrier wall is currently on track to be completed by the early spring 2013, significantly ahead of the previously planned completion date in December 2013. The barrier wall is the most critical component of the dam safety project and will have to be completed prior to raising the lake level.
Also before raising the lake, a dam safety team composed of an outside advisory panel of experts and experts within various Corps offices nationwide will review data on the completed barrier wall to ensure it meets requisite safety and quality standards.
“We expect this review to happen within one month of the barrier wall completion,” Getty said.
“The purpose of this initial increment is to determine how the dam reacts to these higher sustained lake levels before raising the lake further,” Getty said. “Instruments installed in the dam will be monitored and analyzed during this time. If the dam performs as expected during the initial incremental pool raise and after another safety review, the goal is to return the lake to its historical operating levels without further increments.”