By BILL MARDIS
A planned safety review this winter that could clear Wolf Creek Dam for normal operation is not expected to be a big deal.
Don B. Getty, manager of the Wolf Creek Dam Rehabilitation Project, said this week the safety review probably won’t last but a couple of hours. The review will be done by a panel of experts looking at information now being assembled by engineers at the Nashville District of the U.S. Army Corps of Engineers.
Since the protective concrete barrier wall was completed in March there is no indication of problems at the dam, Getty said. The $594 million rehabilitation project included insertion of a wall of concrete, 4000 feet long, 275 feet deep and at least two feet thick on the upstream side of the earthen section of the dam.
Including grouting (pumping liquid concrete in the dam) and creation of the barrier wall, engineers say enough concrete was put in the dam to build a sidewalk five feet wide from Jamestown to Washington D.C. Pyle Concrete Inc. of Columbia built a new plant across U.S. 127 from Lake Cumberland State Park to supply concrete for the dam.
The rehabilitation project, of a scope never before done in the world, was necessary after Wolf Creek Dam in 2005 was classified in high risk of failure. The dam was built above porous limestone rock that deteriorates in water. Over the more than 60-year life of the dam, caverns, some 40 feet wide, developed beneath the structure and seepage became uncontrolled.
Wolf Creek Dam is the most monitored structure of its kind in the world. More than 300 instruments that detect water and soil movement have been installed in the dam. Some are so sophisticated that Corps engineers in Nashville are electronically alerted in case of a problem.
The lake was held about 40 feet below normal for more than six years while the dam was being repaired. The level was allowed to rise 20 feet this summer following completion of the concrete barrier wall.
The annual drawdown of Lake Cumberland has begun and the target for Labor Day weekend is at or about 698 feet above sea level. That will be about 3 feet lower than the current level.
After summer’s final holiday, the drawdown will continue until the lake is at 690 feet above sea level (11 feet lower than now) by early to mid October. The lake will remain at this level for several months while the remaining rock used to stabilize the earthen section of the dam during rehabilitation is removed from the work platform. Also, large riprap (broken stones loosely deposited to provide a protective foundation) will be put in place.
Getty said if the dam passes this winter’s safety review, plans are to go back to normal operation next spring. Normal level during the summer vacation season is 723 feet above sea level, or at the tree line. At this level, Lake Cumberland averages 90 feet deep and stretches from near Corbin through Pulaski County to west of Jamestown. It is 101 miles long has more than 1,200 miles of shoreline.
A level of 723 feet is not guaranteed during summer 2014. To reach this level Mother Nature must cooperate with plenty of rainfall during spring and early summer.