In Jan. 27 Issue
Delays caused by drilling problems in a critical area near the concrete portion of Wolf Creek Dam are expected to push completion of the project and the money to fund it beyond the previously announced figures and date of December 2012, according to the Corps of Engineers.
No final date for completion on the project has been announced.
The foundation remediation contract for the multi-million dollar rehabilitation is approximately 44 percent complete as of now. Recent instrumentation data and observations from the Corps have shown no abnormalities in terms of stability of the dam. This data is monitored 24 hours per day, seven days per week.
Last week the Corps gave their first project update since Nov. 1 of last year, saying that despite the recent cold and snowy weather work has continued on the giant structure as normal.
Treviicos Soletanche JV, the dam's construction firm, is continuing grouting in Critical Area I, the most questionable area beneath the structure where the most seepage has occurred, and is currently installing the protective concrete embankment wall and the pile barrier wall. They are also in the initial stages of gallery and plaza grouting, according to the Corps.
The Corps awarded the main foundation and plaza grouting contract to The Judy Company at a price of $6.8 million. The preconstruction conference was Jan. 20, at which time notice to proceed on the project was given. The expected contract completion date for that portion of work is May 2012.
The Corps said in their update that 289 protective concrete embankment wall (PCEW) panels and 186 secant piles have been inserted in the large earthen portion of the dam. The PCEW panels are designed to fortify a stabilizing wall in the earthen part of the dam ahead of drilling for the secant piles that will form the permanent concrete barrier wall.
Other construction activities currently in the works include directional drilling, pre-drilling, pile drilling, concrete placement and verification coring.
When the remedial work is complete, the earthen portion of Wolf Creek Dam will be packed with three concrete walls, according to the Corps. These include the diaphragm completed in 1979, the protective concrete embankment wall and the permanent barrier wall.
The Corps and Treviicos Soletanche JV are in the proposal and negotiation stage of a modification to the contract to install cased secant piles in the cave and core trench area of Critical Area 1. Negative impacts to project cost and completion schedule are expected, which means the figure will likely be above the estimated $584 million to complete the project and how much longer beyond December 2012 it will take to complete work on the structure.
The final impacts will be released upon completion of the contract negotiations.
Subcontractor Hayward Baker Inc. continues their drilling and grouting of the rock foundation below the cave and core trench features in Critical Area 1.
All work in that area was suspended in March last year after an increase in movements in the range of one inch or less was observed primarily in monitored cracks along the crest of the dam, according to the Corps.
The initial concern was these movements might be caused by a deep slope movement in the upstream embankment. Work resumed on Critical Area I in the fall with a new method that differs from the original in that the overlapping concrete piles that form the barrier will be installed through temporary steel casing advanced ahead of the excavation.
This move isolates the cave and cutoff trench material outside the casing from the effects of the construction activities inside the casings, according to Michael Zoccola, chief of civil design for the Nashville District.
Zoccola said this approach was slower but that it satisfied concerns regarding dam safety and constructability.
Hayward Baker Inc. has completed a line of holes to close area between the ends of the upstream and downstream grout lines and are currently drilling steep angled holes at the west end of the work platform to tie in with the grout lines drilled from the gallery beneath the concrete dam in 2007.
Currently there are no plans to raise the pool level elevation above 680 ft. above sea level until the main barrier wall is completed, which means the lower lake level will be here for a while longer.