by Bill Mardis
Wolf Creek Dam —
The seven-year rehabilitation of Wolf Creek Dam is 88 percent complete and the project is still on track to be finished in about 14 months –– December 2013.
Bill DeBruyn, resident engineer at the dam, said 1,053 of the concrete piles to form a permanent barrier wall to stop uncontrolled seepage are in place, leaving 144 more piles to complete the wall.
The permanent wall is being created by drilling 50-inch diameter holes 275 feet deep from the work platform on the upstream side of the dam to about 100 feet into the limestone bedrock. Each hole, filled with 140 cubic yards of concrete, is called a pile.
The 50-inch holes overlap, like Olympic rings, forming a permanent wall that must be at least two feet thick. The new wall extends into a deeper and more stable limestone stratum than immediately below the dam. Another wall, installed during the 1970s, was not long enough or deep enough to stop uncontrolled seepage that undermined integrity of the structure.
It takes a lot of concrete for the wall currently being formed. At onset of the project, an engineer said it would take enough concrete to build a sidewalk 5 feet wide from the dam south of Jamestown to Washington, D.C.
DeBruyn laughed at this analogy. He said the total project will require 290,000 cubic yards of concrete. According to our calculation, a cubic yard of fresh concrete weighs about 3,700 pounds, so a total of 1,073,000,000 (one billion, 73 million) pounds of concrete will have been inserted in the dam when the rehabilitation project is complete. Pyle Concrete Company of Columbia built a plant on U.S. 127 across from Lake Cumberland State Park to supply concrete for the dam project.
Up to now, 270,000 cubic yards of concrete have been used. The 144 additional piles to complete the wall will require another 20,000 cubic yards of concrete, DeBruyn said.
He estimated that 41 percent of the permanent wall is complete in Critical Area 1, an unstable section of the dam near where the earth wraps around the concrete monolith. This part of the structure is undermined with cavities that initially wouldn’t accept grout and ended up delaying the rehabilitation project about a year.
All the pilot holes in Critical Area 1 have been drilled, DeBruyn said. Pilot holes are 8 inches in diameter and guides the 50-inch drill as it descends 275 feet to form another part of the permanent wall.
Wolf Creek Dam has been plagued with seepage since the gates closed and the lake began to fill in December 1950. A serious leak developed in 1968 and was controlled by intense grouting and installation of a barrier wall during the 1970s.
Seepage continued and in 2005 an outside panel of experts declared Wolf Creek Dam in high risk of failure. A complete rehabilitation of the dam was deemed necessary at a cost now projected at $594 million.
Lake Cumberland in January 2007 was lowered 40 feet to ease pressure on the dam and facilitate rehabilitation of the dam. When the project is completed the lake will be raised in increments and each level will be monitored by more than 350 instrument in the dam.
The Corps hasn’t promised a full lake by Summer 2014 but Don Getty, manager of the rehabilitation project, assured it will be higher than it is now.
Bill Mardis may be contacted at email@example.com or telephone 451-4919.