In Mar. 13-19 issue
By Greg Wells
Times Journal Managing EditorFishing below Wolf Creek Dam from boats and from the air on Tuesday. Reports make the coming spring season look good.
WOLF CREEK DAM - The U.S. Army Corps of Engineers announced the allocation of $57 million for work on Wolf Creek Dam, but they report not being ready to make a decision regarding this summer's pool level.
Officials reported that this new infusion of money will keep the work on the dam progressing. The Corps' Nashville office, which is in charge of the project, has reported marked improvements at Wolf Creek Dam since lowering Lake Cumberland to an elevation of 680 feet above sea level and beginning the grouting program last year.
As drilling and grouting have moved forward at the dam, a significant portion of the upstream grout line has reached closure, according to the new Corps report; sixty percent of the total length of the embankment holds a continuous line of grout.
One of the areas noted as the worst for seepage in recent reports as well as in the early 70s is what has been referred to as the "wraparound" where the earthen portion of the dam meets the concrete portion. In the early 70s, when the condition of the dam had deteriorated there were sinkholes in the dam and muddy discharge welling up into the river just below the dam.
Mike Zoccola, the chief of civil design branch at the Nashville office of the Corps reports the other location of bad seepage was also located during the previous repair.
He said the wraparound and another area near the center of the earthen portion where engineers has stepped the other wall down deeper into the bedrock because "they hit some bad rock."
During previous meetings, Corps officials reported that the latest round of seepage began after the lake was held at near-record low levels because of flooding on the Ohio and Mississippi Rivers.
But Zoccola reports that the condition of the dam, judging by their observations and instrument readings, is much better now; though not all of that may be attributable to the work on the dam.
"We have observed that the wet areas that we have been monitoring below the dam have dried significantly over the last year," Zoccola said. "Drawing the lake down made a big difference in those and the drought made a difference as well."
The issue on the mind of tourism officials and lake-related business owners of late has been the suggestion by the Corps that the level of the lake may be increased for the summer tourism season, if the grouting is successful at significantly slowing the seepage.
According to a release this week, "the Corps has a process for determining future lake levels at Wolf Creek Dam. With this process, decisions will be based on completion of structural improvements to the dam's foundation, and continued stable and improving conditions at the project. Closure of the initial upstream grout line is the first structural improvement."
Previously staff at the work-site have explained that there are two lines of grout holes being drilled in the dam on each side of the planned wall that will be placed through the dam into the bedrock.
The up-stream side, or the line of grout holes between the lake and the wall that is to be built, as well as the down-stream grout line, are installed in three stages.
The first set of holes are drilled 20 feet apart then they come with a secondary line of holes that are centered between the previous set, at 10 feet. Plans include options for a tertiary set on 5-foot centers and if necessary a fourth or quaternary, set of bore holes that will be just over 2 feet apart.
The contractors had been moving on to the downstream line of grout while jockeying for position to install the secondary and tertiary holes and grout fills, but they have been redirected recently to focus on finishing that up-stream side so the Corps can make a judgment on the success of this step and therefore whether the lake level can be allowed to go higher this year.
"It will be at whatever point we've met all the closure criteria for the upstream line." Zoccola said. "Once we see that the holes have tightened up, we can begin the procedure (to decide what the lake level will be.) We're down to tertiary holes on the upstream side. If don't get results needed may have to go to the fourth stage."
The Corps reports that the contractor will continue to work on an accelerated schedule with the intent to achieve closure on the initial grout line as quickly as possible.
"We've accelerated the contractor as much as we can," Zoccola explained..
Once the contractor completes the first line of grouting on the lake side of that work platform at the side of the dam, and instrumentation shows the project is stable and improving, is when they may be able to say the water level in the lake can increase.
"Our plan is that once we meet these structural milestones, we will bring the lake up in stages with no stage anticipated to be more than 10 feet," Zoccola said. "If we feel we can raise the lake level at completion of first line of grout it would be by 10 feet.
The lake level was reduced and held for the past year at 680 feet above mean sea level. That's about 40-45 feet below the tree line. During an average normal winter, the lake's level is reduced to around 685-690 feet, but usually allowed to rise to the "normal summer pool" of 723 feet above sea level.
Zaccola said it would not be allowed to rise to the 700-foot level, as many in the area have advocated.
"We're cognizant of the fact that people would like the lake raised but safety of people downstream is our first concern," he said.
As to the next step in the repair process, the Corps reports that a number of firms have shown interest in bidding on the project to place a concrete wall within the dam, farther into the bedrock than the existing concrete structure.
They expect to have the contract for the barrier wall awarded sometime after the deadline for submissions in mid-April.
Zoccola explained that the timing for a decision on who will do the work will depend on how many and what type of proposals are offered.
"I would say mid- to late-summer… probably an August timeframe," he offered. "Again, that is a fluid date since we will take however long is required to make the best selection."
There may be some good news relating to how long it will take to complete the project.
"Our construction estimate has it (the construction of the wall inside the earthfill portion of the dam) at a five-year project, but the indications from the contractors are that they could do the job quicker," Zoccola said. "We're waiting for their proposals to see what they say."
Due to recent heavy rain in the region, the level of the lake has increased around 7 feet in the past week. On Wednesday, it was at the highest level since Jan 27, 2007.
In order to maintain the announced lowered level of the lake for work on the dam, release of water through Wolf Creek Dam was increased to a high continuous flow of 17,170 cubic feet per second, with five of the dam's six power turbines generating around the clock.
Last summer the lake reached a level of 678.61, which was the lowest it had been since the earlier work was bring done on leaks at the dam in 1981. The average summer pool level for the lake is 723 feet above sea level.
Spending for the original dam construction was $81 million. The cost to repair leak in dam during late 1970s was $96.4 million. That the dam was leaking was discovered in 1967.
Present construction estimates for repairs to the dam are $309 million, and work began in 2006, but the project was truly underway in January of 2007.
Bill Peeples with the Corps' Nashville office noted that the project has received extensive support from President George Bush and the congressional delegations of Kentucky and Tennessee in the past and that to date, the project has been fully funded.
Peeples' office reports that data from this work continues to show the emergency declaration at Wolf Creek was appropriate, and the foundation is in the condition they expected.
They report that two critical areas remain and are the focus of current work, but distress indicators and observations show the foundation of Wolf Creek Dam is stable and improving every day.
Weekly updates of work at Wolf Creek Dam can be found on the Wolf Creek Seepage Rehabilitation website, www.lrn.usace.army.mil/WolfCreek
The weekly reports and discussions about them can be found on lakecumberland.com
, which also carries the numbers of daily lake statistics and detailed daily records since the work began.