Meetings begin to discuss stability of Wolf Creek Dam
By BILL MARDIS, Editor Emeritus Commonwealth Journal
Officials of the U.S. Army Corps of Engineers began a series of meetings Tuesday afternoon during which the integrity of recently inserted permanent barrier wall in Wolf Creek Dam will be determined as well as performance of the mile-long structure that impounds Lake Cumberland.
Don Getty, manager of the $594 million Wolf Creek Dam Rehabilitation Project, said two things will be discussed during the meetings: (1) Quality of the barrier wall to assure it was built to specifications, and (2) performance of the dam based on information from 350 monitoring instruments inside the dam. The 4,000 foot barrier wall through the earthen section of the dam was completed last Wednesday when the last pile was poured.
End result of the meetings is expected to be a green light from Brigadier General Margaret W. Burcham, commander of the Great Lakes and Ohio River Division, to allow the lake to rise 20 feet by June, beginning of the 2013 tourism season.
“April 1 is the target date for allowing the lake level to begin rising,” said Getty. He noted, however, this date could vary a few days. Also, sufficient rainfall is necessary to bring up the water level.
A reporter wondered if it is determined the barrier wall is properly installed, and if pressure-reading and material-movement instruments inside the dam indicate integrity, is there a chance the lake would be allowed to rise to historical operating levels (723 feet above sea level) this year?
“I don’t think so,” said Getty. The 20-foot rise this summer will raise the lake from its current target of 680 feet above sea level to between 700 and 705 feet. He said it is more likely the lake will remain just over 700 feet this summer and the green light to raise the level to normal pool stage will be given in December for the 2014 vacation season.
Excessive rainfall during the past couple of weeks in the Cumberland River Basin has raised the lake about 10 feet above the target 680-foot level. Some 21,320 cubic feet per second are being released through the dam to reduce the water level.
Completion of the barrier wall did not completely finish the rehabilitation project. Weddle Enterprises, Somerset, is currently narrowing the work platform on the upstream side of the dam from 75 feet wide to a 30-foot-wide platform that will remain. The platform was built to accommodate heavy equipment that fashioned the barrier wall by drilling 50-inch, overlapping holes filled with concrete.
The wall, a minimum of two feet thick, extends from the work platform 275 feet downward to about 100 feet into limestone bedrock beneath the dam. The project, of a scope never done anywhere in the world, is designed to stop uncontrolled seepage that has plagued the dam since it was completed in December 1950. Wolf Creek Dam in 2005 was declared in high risk of failure and the water level was lowered 40 feet in January 2007 to facilitate the current rehabilitation project that is nearing completion.
Part of the information available to ongoing meetings of Corps engineers is core drillings into the newly inserted wall to assure integrity of the concrete. This type of evaluations has been going on throughout the construction process and is winding down now, Getty said.
Wolf Creek Dam is bolstered with two additional walls: A shorter barrier wall extending about 15 feet into the limestone bedrock was installed during the 1970s following a near breech of the dam during the late 1960s, and a protective concrete embankment wall fashioned with 6 feet-by-9 feet concrete panels to stabilize the earthen embankment while the most recent wall was inserted.
The near-vacant work platform is testimony the dam rehabilitation project is nearing an end. Most of the equipment has been moved and many of the up to 275 workers are no longer on site.