TheTimesTribune.com, Corbin, KY
SOMERSET, Ky. (AP) — Construction on a cutoff wall has started at Wolf Creek Dam with officials saying it is designed to prevent erosion from undermining the electrical switchyard near the base of the structure.
Wolf Creek Dam Rehabilitation Project Manager Don Getty said the new section of cutoff wall will be 180 feet long and constructed by drilling 50-inch overlapping holes, same as the 4,000-foot-long permanent concrete barrier wall was inserted in the dam during the past six years.
Getty told The Commonwealth-Journal (http://bit.ly/13eVc9i ) the cutoff wall near the switchyard won’t be as deep as the 275-foot-deep wall in the dam.
The project is an extension of the cutoff wall installed during the 1970s after serious leaks developed in the structure a decade earlier.
Many believe the condition of Wolf Creek Dam during the late 1960s was more serious than in 2005 when the dam was declared in high risk of failure. Intensive grouting slowed the seepage, and a cutoff wall, not long enough and not deep enough, was installed during the 1970s.
A just-completed, $594 million rehabilitation of the dam is believed to be a permanent fix for the uncontrolled seepage problem.
Engineers believe there is a connection between fluctuation of tailwaters and undermining the switchyard area, Getty said.
“This extended cutoff wall near the switchyard has absolutely nothing to do with the lake,” Getty said.
The second barrier wall in the earthen section of the dam was completed in March and the lake was allowed to rise 20 feet above the target operational level during the six-year rehabilitation of the dam. The lake, pending another safety review, is scheduled to return to historical operation next year.
Getty said current work on the cutoff wall is near the powerhouse and is not affecting fishing immediately below the dam.
“That still doesn’t mean it’s not dangerous to get up close to the dam,” Getty said.