In Dec. 11 Issue
Things have been quiet on Wolf Creek Dam for the past few months, but that's about to end.
As the initial contractor built a large work platform on the lake side of the nearly 3/4-mile-long earthfill portion of the huge structure and poured over 800,000 gallons of grout into areas that were leaking, there was a lot of activity.
But as they completed their major work and moved out, the signs of work activity were greatly reduced. In the past few months, the most visible outside work has been the occasional survey crew and those checking readings of the dozens of devices installed to watch for any change in seepage.
In the various US Army Corps of Engineers reports they report that the major portion of the grouting appears to have been successful, reducing the seepage until the major project - placing a very large concrete wall (called a diaphragm) inside the earthfill portion can be placed over the next several years as the "final" - and long-term - solution toward fixing the water seepage through and under the dam in the area's subterranean caves and flow holes.
Work on the grouting of the major "critical area" near where the earthfill portion of the dam joins the huge concrete monoliths section was called off after the contractor's work was not only unable to successfully stem the seepage there but may have been contributing to the problem. Lt. Col. Bernard Lindstrom, the head of the Nashville District of the Corps of Engineers, told a meeting of marina operators and the press in late July that it was decided the consistency of the grout used then wasn't working and may have actually contributed to a minor shift in the dam nearly leading to an emergency drawdown just before the July Fourth holiday.
A decision was made to install more meters at the location and monitor it closely, but hold off on further efforts until other possible methods were considered. Apparently the decision to stop injecting the grout was a good one, as the Corps notes the seepage and movement at the location has been reduced since then.
Plans for the coming work place, according to the Corps, mark this project as one of the largest of its type in the world. Essentially, they will be placing a four-foot-wide concrete dam that is roughly 450 feet high inside a dam that holds back one of the largest man-made reservoirs of water on the planet. The wall will be placed as deep into the bedrock as the dam is high, and from the bedrock level nearly as high as the dam.
The idea is to block all seepage paths in the dam and under the dam to a point below the karst type of bedrock that is riddled with water passages. It will be built into the rock wall at the lake's edge on the north side, and extend in front of a portion of the concrete monolith section of the dam. When completed, seepage should be reduced to non-threatening levels and Corps officials have stated they believe the work will insure the dam's safe existence for the next hundred years.
"With the barrier wall," says Allison Jarrett, a public affairs officer at the Nashville office of the Corps, "we are drilling through approximately 180 feet of embankment and 95 feet into rock near the embankment/concrete tie-in for a total depth of 275 feet. With the combination of overall depth and the depth of the rock, the Wolf Creek barrier wall is unique." She noted the significance of the project: "Other walls have penetrated as much or more rock, but just not at the total depth as we are here. Other walls have had an overall depth greater than this, but did not penetrate as much rock."
Action should begin to pick up noticeably next month, according to the most recent information from Corps sources. It is expected that drilling and grouting equipment will begin arriving on site by the first of January, and some work should begin by the end of January. The first special equipment - some will have to be built just for this project - is scheduled to arrive in February and March, and the first phases of the wall construction would start soon after.
Due to the space needed for the equipment and work area, the wide concrete platform that was built along the lake side of the dam for the grouting work will have to be expanded, the Corps announced recently.
Currently, it is about the width of a four-lane road and concrete surfaced. Plans call for it to be widened another dozen feet. When asked, Jarrett said that the widening work on the platform area was always part of the project.
A Russell County local sub-contractor supplier, Pyles Concrete, is in the process of erecting a concrete batch plant a few miles from the dam along U.S. 127, across from the entrance to Lake Cumberland State Park. Except for work trucks moving along the highway, however, traffic along U.S. 127 over the dam should be little affected by the coming work, Jarrett said.
"We expect to complete the wall construction without any long-term lane closures," states Jarrett, "since no work will be done from the crest of the dam." She adds there may be occasional traffic halts when moving large equipment from one staging area to another.
Representatives from Treviicos-Soletanche JV (barrier wall contractor) last month met with Russell County Judge Executive Mickey Garner to discuss ways the project can make a positive impact on the community.
The joint venture is being proactive in hiring local employees, utilizing local subcontractors, and purchasing supplies and materials from local businesses. It was agreed the the Corps and JV will provide a quarterly update at the county's Fiscal Court meetings beginning in January 2009.