User:Fourmica/work/Wolf Creek Dam/

The Wolf Creek Dam is a dam on the Cumberland River in the western part of Russell County, Kentucky. It was constructed to generate hydroelectricity and prevent flooding but is better known for creating Lake Cumberland, which has become a popular tourist attraction.

History
Construction of Wolf Creek Dam was authorized by the Flood Control Act of 1938 and the River Harbor Act of 1946 as part of a comprehensive plan to develop the Cumberland River Basin; however, because of World War II and other factors, construction was not completed until 1950. The last of the power generators was installed in 1952. While several small towns downstream from the dam were adversely affected by its construction, such as nearby Creelsboro, Kentucky, the dam is credited with preventing several hundred million dollars in flood damage.

Seepage problems
In 1968, signs of seepage problems within Wolf Creek Dam's earthen embankments and foundation were discovered. Sinkholes appeared at the downstream toe of the dam, and muddy water was observed in the dam's outflow channel. The seepage problems were traced to the karst geology of the region which allows for the dissolution of limestone in the dam's foundation. Solution channels caused by this process allow piping to occur, which adds to the rate of erosion in the foundation.

A short-term solution of grouting the existing seepage channels was employed immediately; grouting in the dam foundation ran from 1968 to 1970 and is credited with saving the dam. Construction of a long-term solution began in 1975 in the form of a seepage cut-off wall. A concrete diaphragm wall was chosen as the appropriate cut-off solution and extended through the earth embankment into the rock foundation. The cut-off wall was completed in 1979.

Current status
Continuous monitoring of the dam shows that seepage problems have not been completely alleviated. Seepage has likely found new paths around, and possibly through, the cutoff wall currently in place. In recent years, increased seepage rates have been detected.

Since March 2005, around the time when increased seepage rates were discovered, Lake Cumberland has been held at nearly constant water levels to reduce the stresses placed on the structure and its foundation.

In late January 2007, the U.S. Army Corps of Engineers placed the dam under a 'high risk' for failure designation, along with Center Hill Dam in Tennessee, both of which are two major dams upstream from Nashville, Tennessee. A new long-term solution has been proposed to solve, or control, the current seepage problem. A grout curtain and a new concrete diaphragm wall of greater dimensions will be constructed with newer technologies. To reduce the current stresses on Wolf Creek Dam, and thus the risk, the Corps believes they should lower Lake Cumberland to 640 feet (195 m), 83 feet (25 m) lower than normal summer levels. However, this will affect up to 200,000 area citizens' water supply and has also met resistance from marina owners, so the water level has remained at 40 feet (12 m) below its normal level. This lowered lake level is to be held for an indefinite amount of time and will be subject to frequent review. . Wolf Creek Dam is also currently undergoing significant remediation measures to control the current seepage problem that has forced the high risk designation.

Phase one remedial work began in March 2006. Phase two, which includes grouting the dam's foundation, began in January 2007. Remediation is expected to be complete in 2014 and cost an estimated $309 million. A risk-benefit analysis indicates that the benefit to cost ratio is 7 to 1.

If Wolf Creek Dam fails, the estimated loss of life is 100 individuals and three billion dollars. In October 2007, Popular Mechanics cited Wolf Creek Dam as one of the top five disasters waiting to happen in the United States.

Public meetings
Several public meetings were scheduled by the US Army Corps of Engineers with regard to the current status of Wolf Creek Dam, Center Hill Dam and Lake Cumberland. Meetings took place throughout the affected region in February and April 2007.