Drilling operation at Wolf Creek Dam coming to a close soon
By BILL MARDIS, Editor Emeritus Commonwealth Journal
The 4,000-foot-long protective concrete barrier wall to permanently fix Wolf Creek Dam is 100 inches from completion. It is a project of a scope never done anywhere in the world.
As of Tuesday, 1,198 piles had been created to form the wall in the earthen section of the dam that impounds Lake Cumberland. There are only two more piles to go.
Don Getty, manager of the Wolf Creek Dam Rehabilitation Project, said the wall probably will be completed sometime next week. It will finish a barrier wall that extends through the earthen section of the dam and 100 feet into limestone bedrock beneath the dam.
Getty said the last hole, or pile, is “out of vertical tolerance” and will be drilled with a special bit brought from overseas. Getting the special bit is not supposed to cause much of a delay and is probably already on site, Getty said. He theorized the special bit was shipped from general contractor Treviicos-Soletanche Joint Venture’s headquarters in either Italy or France.
The 50-inch overlapping holes are drilled by following an 8-inch pilot hole. Getty indicated the final hole being out of vertical tolerance is not a big deal. There are more ways than one to correct the problem, and it has happened before, he said.
A pile is a hole, 50 inches in diameter and 275 feet deep, filled with 140 yards of concrete. It forms part of a wall, 4,000 feet long and a minimum of two feet wide.
The wall extends from the work platform on the upstream side of the dam to about 100 feet into bedrock beneath the dam. Purpose of the wall is to stop uncontrolled seepage that has plagued the structure since the lake was impounded 62 years ago.
Lake Cumberland is 101 miles long and averages 90 feet deep. The 65,000 acres of water put a lot of pressure on Wolf Creek Dam and seepage has been a problem from the beginning.
The dam in 2005 was classified in high risk of failure and a $594 rehabilitation was deemed necessary. The lake has been held about 40 feet below normal since January 2007 to ease pressure on the structure and facilitate the repair work.
Mike Zoccola, chief of the U.S. Army Corps of Engineers’ Design Branch, said the formula to find the pressure at any depth is easy: “62.4 X depth.”
Before the lake was lowered in January 2007 to facilitate repairs to the dam, depth of the water at the dam was about 250 feet. At this depth, according to Zoccola’s formula, there were 15,600 pounds of pressure against every square foot of the dam at its bottom.
Bill DeBruyn, resident engineer at the dam, 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.
That is enough concrete, according to an on-site engineer, to build a sidewalk 5 feet wide from Jamestown near the dam to Washington D.C.
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.
You can see light at the end of the tunnel. The U.S. Army Corps of Engineers announced January 25 that the lake will be allowed to rise 20 feet, to between 700 and 705 feet above sea level, by this summer’s vacation season. Brigadier General Margaret W. Burcham, commander of the Great Lakes and Ohio River Division, will give the green light for the lake to rise.
Current projections are the level will begin to rise April 1, and depending on spring rainfall, the lake should rise 20 feet by June.