Dam project pushed back

By BILL MARDIS, Editor Emeritus
Commonwealth Journal

Somerset October 22, 2009 09:09 pm

— Problems with directional drilling of pilot holes have delayed work at Wolf Creek Dam and pushed back the projected completion of the dam rehabilitation project to December 2012, about two months later than the contract deadline.
David Hendrix, project manager for the $584 million repair project, said the delay also will mean evaluation of the level of Lake Cumberland won’t be done at least until December 2010, about two months later than projected. Engineers said earlier when the permanent wall has been installed in two critical areas of the dam by next October the current lake level could be evaluated.
Tourism interests around Lake Cumberland have been clinging to the October 2010 evaluation of the dam repair progress that might allow the level of Lake Cumberland to be raised, hopefully 10 feet, for the 2011 vacation season.
Despite the projected delay, Hendrix didn’t rule out the possibility of a higher lake level during summer 2011. “Even if we could make the evaluation as late as March (2011) spring rains could allow a change in the lake level,” he said.
Problems with drilling pilot holes, 8 inches in diameter, have caused the delay, Hendrix explained. The pilot holes are guides for 50-inch circular shafts that will be backfilled with concrete to form the permanent barrier wall. Three of the large holes have been completed in Technique Area 1, one of two test areas to determine integrity of the work, Hendrix noted.
The project manager emphasized that problems with drill alignments have been corrected and work is proceeding. He said the general contractor is still bound by the October 2012 completion date, but indicated no decision has been made for possible financial penalties because of the projected delay.
A protective embankment wall made of concrete panels, 6 feet wide and 10 feet long, is being inserted in the earthen section of the dam to stabilize the embankment while the permanent barrier wall is installed.
Hendrix said 118 of the 427 panels necessary for the protective concrete embankment wall have been inserted. However, a quality control procedure has determined four of these panels do not meet specifications and another 20 panels are being evaluated.
When completed, three concrete walls will strengthen and protect Wolf Creek Dam. The diaphragm installed during the 1970s will remain; the stabilizing concrete embankment wall that reaches the base of the earthen embankment will stay; as well as the permanent barrier wall that will extend the entire length of the earthen structure and deep into the bedrock.
Lake Cumberland has been held near 680 feet above sea level, about 40 feet below normal, since January 2007 to facilitate repairs at the dam. The lower water level has had an adverse economic impact on the 10-county Lake Cumberland area, including Pulaski County.
The mile-long structure has been plagued with seepage since it was impounded in 1951. Uncontrolled leaks during the late 1960s was temporarily repaired with a concrete diaphragm inserted in the earthen section of the structure. This first barrier wall proved too short and too shallow and in March 2005 the Corps decided a major rehabilitation of the dam, declared in high risk of failure, was necessary. A public announcement of the crisis was made in August 2005.
A contract was awarded to Treviicos Soletanche JV, a joint French-Italian firm, to insert a second concrete barrier wall that would extend the entire length of the earthen part of the dam and up to 100 feet in the bedrock beneath the dam. Engineers said this will be a permanent fix for the dam and ensure the future of Lake Cumberland.