Somerset —
The calendar has finally turned. This is 2013, the year rehabilitation of leaky Wolf Creek Dam is projected for completion.
For seven long years, seven summers, seven vacation seasons, local businesses so dependent on tourist trade have persevered. Lake Cumberland, for what seems an eternity, has been kept as close as possible to 680 feet above sea level, about 40 feet below normal. Only one more summer to go means normalcy or near normalcy is just around the corner.
December 2013 is the target date for completion of the $594 million repair project. Engineers have said the barrier wall being inserted in the earthen section of the dam will permanently fix the mile-long structure, plagued with leaks since the gates were shut 62 years ago.
Lake Cumberland may not be at historic levels during Summer 2014, “but it will be higher than it is now,” project manager Don Getty has promised.
The lake will rise in increments after the barrier wall is complete. Each level will be analyzed by 350 pressure and motion sensitive instruments in the dam to make sure the structure is safe. How fast it will rise also depends on Mother Nature; the amount of rainfall during Spring 2014. Lake Cumberland, when full, is 101 miles long and averages 90 feet deep. That’s a lot of water.
All is going well, “ ... smoothly ... I hate to say it, but almost too smoothly,” Getty said this week. “After all, I’m paid to worry,” he laughed.
There is reason to be optimistic. Drilling through the dam is being done in what has been dubbed “Critical Area 1,” a cavern-laced, unstable section of the structure near and about where the earth wraps around the concrete monolith. Getty said all primary holes have been drilled, lessening the risks somewhat.
“There are still risks,” Getty emphasized. “But not as much.”
The permanent barrier wall is formed by drilling overlapping holes, 50 inches in diameter 275 feet deep from the work platform on the upstream side of the dam to about 100 feet into limestone bedrock beneath the dam.
The wall, a minimum of two feet thick, is formed by drilling two primary holes and then a secondary hole in the center of the two primary holes. The holes are filled with concrete.
The barrier wall is complete except in the critical area. Getty said about 60 secondary holes remain to be drilled to complete the wall.
To prevent vibrations during the drilling operation, the drilling is done through a protective concrete embankment wall inserted in the dam before the 50-inch drill bits are used. In other words, the drills go through concrete to the base of the dam and then into limestone rock.
Getty said the barrier wall is 95 percent complete. The overall project is about 85 percent complete, he added.
Part of the overall project will include eliminating the work platform, base of operations for inserting the barrier wall. Getty said some narrowing of the work platform could begin as early as next week.
Seepage has been a problem since the dam was built. A panel of experts in 2005 labeled Wolf Creek Dam in high risk of failure. Treviicos-Soletanche JV, a joint French-Italian company was given a contract to fix the dam, a project of size and complexity never before done.
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