| Wolf Creek Dam | |
 |
|
| Impounds | Cumberland River |
|---|---|
| Locale | Russell County, Kentucky |
| Length | 5,736 ft (1,748 m) |
| Height | 258 ft (79 m) |
| Reservoir information | |
| Creates | Lake Cumberland |
| Capacity | 6,089,000 acre·ft (7,511,000 dam³) |
| Geographical Data | |
| Coordinates | 36°52′06″N 85°08′51″W / 36.8683°N 85.1475°WCoordinates: 36°52′06″N 85°08′51″W / 36.8683°N 85.1475°W |
| Maintained by | Army Corps of Engineers |
The Wolf Creek Dam is a multi-purpose dam on the Cumberland River in the western part of Russell County, Kentucky, United States. The dam serves at once four distinct purposes: it generates hydroelectricity; it regulates and limits flooding; it releases stored water to permit year-round navigation on the lower Cumberland River; and it creates Lake Cumberland for recreation, which has become a popular tourist attraction.
Contents |
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
The dam and its adjacent reservoir reside upon a heavily Karsted bedrock foundation. Karsts formations are large void spaces lying beneath seemly solid species of limestone bedrock. Karsts formations are created when limestone bedrocks are, over time, attacked by water through natural precipitation seepage. The rain or snowmelt water contains dissolved carbon dioxide from the atmosphere, which, in solution, forms a weak carbonic acid. That acid attacks the limestone rock dissolving it, and thereby leading to the voids within the rock formation. When a reservoir of 100+ feet in elevation is raised above this style of foundation, the hydraulic pressure of the water easily dislodges the cementing clays that are in the cracks and void spaces of the under laying Karst foundation.
Keying a concrete dam’s footing form into such a foundation; along with injecting waterproof grout into the void spaces between the dam’s concrete base and the rock foundation (so as to fill the foundation’s voids) will usually create a watertight seal above, at, and below the foundation of a concrete dam, in a Karst locale.
However Wolf Creek, like most multipurpose dams; is mostly constructed as an earth fill embankment type dam. In this form of construction the majority of the dam’s structure (measured by length across the streambed) is a nominally waterproof earth fill embankment body, with only the powerhouse and (if so equipped) the controlled overflow spillway section located within a concrete monolith. In the particular case of Wolf Creek dam, the earth embankment section is placed directly upon the formerly existing streambed; with only the surface soils and clays removed. While the upstream interface between the embankment section's foot and the old streambed is nominally waterproof, the Karst solution channels far under the mass of the earth embankment section proper, can directly attack the porous and not waterproofed foundation of the earth embankment section of the dam. It is this phenomenon that has occurred and led directly to the seepage problem.
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.[1] 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.[1] 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.[1] In recent years, increased seepage rates have been detected.[2]
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.[2] To reduce the current stresses on Wolf Creek Dam, and thus the risk, the Corps believes they should lower Lake Cumberland to 640 ft (200 m), 83 ft (25 m) lower than normal summer levels.[3] 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 ft (12 m) below normal. This lowered lake level is to be held for an indefinite amount of time and will be subject to frequent review.[2]. 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 2012 and cost an estimated $309 million.[2] A risk-benefit analysis suggests a 7:1 benefit.[1]
If Wolf Creek Dam fails, the estimated loss of life is 100 individuals and three billion dollars.[4]
In October 2007, warning sirens were installed in the Dam's surrounding counties[5][6], and Popular Mechanics cited Wolf Creek Dam as one of the top five disasters waiting to happen in the United States.[7]
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. [8]
References
- ^ a b c d Seepage Problem, Wolf Creek Dam U.S. Army Corps of Engineers. Accessed 27 January 2007.
- ^ a b c d Project Manager's Assessment, Wolf Creek Dam U.S. Army Corps of Engineers. Accessed 27 January 2007.
- ^ Bradley, Jeff, et al. (11 April 2007) Wolf Creek Dam Consensus Report: Engineering Risk and Reliability Analysis U.S. Army Corps of Engineers. Accessed 21 October 2007.
- ^ Q's & A's, Wolf Creek Dam U.S. Army Corps of Engineers. Accessed 27 January 2007.
- ^ (20 October 2007) Wolf Creek Dam Issues Prompt Siren Installation WTVF. Nashville, TN. Accessed 20 October 2007.
- ^ (20 October 2007) New Warning System for Several Counties Near Wolf Creek Dam WKBO. Bowling Green, KY. Accessed 20 October 2007.
- ^ Flynn, Stephen. (19 October 2007) 5 Disasters Coming Soon If We Don’t Rebuild U.S. Infrastructure Popular Mechanics. Accessed 20 October 2007.
- ^ Public Meeting Schedule, Wolf Creek Dam U.S. Army Corps of Engineers. Accessed 27 January 2007.
External links
- Lake Cumberland Online Visitor's Guide
- Wolf Creek Dam - US Army Corps of Engineers
- Potential Flooding Maps available online.
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