Findings of an independent review panel indicate the construction of a new concrete dam section might be a better long-term solution than the Corps of Engineers’ current plan to repair seepage that threatens 270-MW Wolf Creek Dam on the Cumberland River.
As a result of the independent peer review, due to be made public by the end of April, the Corps is taking a second look at the concrete dam proposal it once rejected as too costly for fixing seepage through the dam’s foundation.
The 5,736-foot-long, 258-foot-tall rolled earthfill and concrete gravity dam is in Kentucky, 300 miles upstream of Nashville on the Cumberland River. It impounds Lake Cumberland, the largest reservoir east of the Mississippi River.
Earlier this year, the Corps lowered the level of Lake Cumberland to reduce the risk of dam failure and to limit seepage during rehabilitation work. (HNN 1/24/07) Studies following Hurricane Katrina classified the dam as being at ï¿½high riskï¿½ of structural failure.
The Corps has said it would request full funding to $309 million from Congress to accelerate a program of grouting and construction of a concrete diaphragm wall to reinforce the original dam.
However, the independent peer-review panel said replacing a 4,000-foot-long earthen embankment section of the dam with a roller-compacted-concrete dam might be a better long-term solution, the Corps’ Mike Zoccola said.
Zoccola, chief of civil design in the Corps’ Nashville District, said the Corps would take a more detailed look at building a new concrete dam section. The idea was studied and ruled out several years ago, due to estimated costs of $500 million, compared to the current $309 million plan.
Zoccola said the Corps would take about three months for a concept-level study examining technical challenges, construction costs, and time for construction. If it is determined a new concrete dam section might be feasible, then the Corps will conduct a feasibility study of the idea.
Currently, the Corps is filling voids in the rock beneath the dam with grout, a job it expects will be completed by December. Under the current scenario, rehabilitation could be completed in 2013.
Similar problems face 135-MW Center Hill Dam
Meanwhile, the Corps’ Nashville District also plans to rehabilitate the foundation of 135-MW Center Hill Dam, which has a history of seepage problems that have worsened in recent years.
The Corps approved $240 million for the plan in August 2006. As a precaution, the project’s water level has been reduced to the lower end of its operating range. Preliminary work for a grouting program is under way. Work to improve the dam’s long-term reliability could be completed in 2014.
Center Hill is near Lancaster, Tenn., about 120 miles upstream of Nashville on the Caney Fork River, a tributary of the Cumberland. The 250-foot-tall dam consists of a 1,382-foot-long concrete section and 778-foot-long earth embankment.
Both Wolf Creek and Center Hill are included in an unrelated program to rehabilitate hydropower equipment in the Nashville District. (HNN 6/26/06)
Generation loss during Wolf Creek rehab spurs utility rate hike
The Kentucky Public Service Commission has granted a $19 million interim rate increase to East Kentucky Power Cooperative Inc., partly due to generation losses at Wolf Creek as a result of lower lake levels.
The PSC said April 2 the increase is justified to maintain the utility’s financial and operational viability. The commission said EKPC faces costs associated with the lowering of Lake Cumberland during repairs to the dam, including the prospect of purchasing higher-cost electricity to replace low-cost Wolf Creek hydropower.
However, the commission also noted Wolf Creek Dam was only one of many factors contributing to East Kentucky Power’s deteriorating financial condition.