By BILL MARDIS, Editor Emeritus
Somerset — The chief geologist for the United States Army Corps of Engineers’ Nashville District has refuted statements to be published by a national magazine that says limestone rock in Wolf Creek Dam is dissolving at an alarming rate and the risk of dam failure has not been reduced.
Jody Stanton said the story in the May 2008 edition of Popular Mechanics “... presents several serious misconceptions as written.”
The magazine story to be on newstands in about a week says “ ... despite the ongoing construction work, the danger of collapse hasn’t been significantly reduced and probably won’t be for years — the earliest possible completion date for the work is 2012 ... ”
Stanton, in a statement released by Bill Peoples, chief of public affairs for the Corps’ Nashville District, emphasized that “ ... the limestone is not dissolving at an alarming rate. The cavities in the foundation have developed over many thousands of years and are pre-existing, not the result of ongoing rapid dissolving of the rock,” he assured.
“Increased seepage is the result of erosion of clay filling, which is commonly found in these pre-existing limestone cavities. The seepage increase is being inferred from indirect measurements and has occurred over a period of many years,” said Stanton.
He emphasized that the $309 million, seven-year rehabilitation of the dam was initiated in anticipation of worsening conditions and the possibility that, undetected, more serious situations exist, not a sudden realization in 2005. The Corps announced in August 2005 that uncontrolled seepage in the dam mandated major rehabilitation of the earthen section.
The level of Lake Cumberland was lowered 43 feet in January 2007 as the repair program got underway. “The drawdown was implemented to reduce risk during the interim construction period,” Stanton said.
The geologist emphasized that the ongoing construction work is producing demonstrable improvements in the foundation conditions and the dam’s performance.
“Prudence dictates that lake levels are held at moderate levels until construction is completed. However incremental lake level increases are being considered as warranted by ongoing evaluations of construction,” the geologist noted.
Stanton admits certain risks are involved in a structure that impounds a 101-mile-long lake.
“Risk is inherent in our reliance on any structure,” Stanton said. “Risk to communities downstream of any dam will always be present. Managing that risk and keeping it to a tolerable level is an ongoing focus for any responsible society,” the geologist concluded.
Wolf Creek Dam has been plagued with seepage problems since it was completed in December 1950. In the late 1960s, two large sinkholes appeared near the electrical grid area immediately below the dam, and muddy water was observed in the tailrace. It took a dozen years and insertion of a diaphragm wall through the earthen section of the dam to correct the problem.
In August 2005 the Corps announced that uncontrolled seepage through the dam required major rehabilitation. The announcement was triggered by an outside group of experts who determined that the dam was in high risk of failure.
An accelerated grouting program has been underway at the dam for the past 15 months. Corps officials have emphasized time and time again that the grouting is making the dam safer every day. A longer and deeper diaphragm wall will be inserted through the earthen section and into the bedrock.
Still under consideration is a higher lake level for the upcoming tourist season. An announcement is scheduled as soon as the first of two grout curtains is completed in the earthen section of the dam.
However, regardless of the lake level, Lake Cumberland is far more ready for water enthusiasts this coming summer than last. The Corps, working with the Kentucky Department of Tourism, has extended all boat ramps in heavily used areas and the lake is now completely accessible.
The state also launched a promotional effort to assure tourists there is plenty of water in Lake Cumberland. With 30,000 acres at 680 feet above sea level, Lake Cumberland is still the largest body of water east of the Mississippi River.
