NASHVILLE DISTRICT

The performance of Wolf Creek's main barrier wall, completed March 6, 2013, continues to meet expectations.   We continue to monitor the instrumentation and daily readings of the heavily instrumented dam are responding as expected.  Lake Cumberland was returned to normal operating levels in the spring of 2014 after formal consultation was completed on the endangered species discovered in the emergency drawdown zone of the lake, the duskytail darter.

In addition to the main barrier wall, a short barrier wall below the dam in the switchyard and powerhouse area was completed in the winter of 2014. The purpose of this wall is to extend a previous barrier wall and to prevent water intrusion from the fluctuating river below the dam into the switchyard area. 

The switchyard wall essentially completed the main construction contract for the project; however, three additional construction contracts are planned to complete the project.  The next contract, Site Stabilization, was awarded to Aspen Construction Aug. 4, 2014.  This contract will restore the project site to pre-construction conditions as much as possible including providing additional topsoil to the 40-acre disposal site and rehabilitating the storm water drainage system below the dam.  A road restoration contract is expected to be awarded in the spring of 2015 to restore the project’s roads to their original condition and convert the newly constructed haul road to a new access road to the Fish Hatchery and Kendall Campground.  This new access road will eliminate the existing difficult intersection at Highway 127.  The final planned construction contract is required as part of the endangered species formal consultation.  It will enhance water quality in the habitat of the duskytail darter in its habitat in the Big South Fork of the Cumberland River.

The overall Wolf Creek Dam Safety project is 97 percent complete and all construction activities are scheduled for completion by 2016.

News Release 14-003: Corps, Fish and Wildlife Service address compliance requirements at Lake Cumberland

Contact
Bill Peoples (U.S. Army Corps of Engineers)
615-736-7161
william.l.peoples@usace.army.mil

or

Tom MacKenzie (U.S. Fish and Wildllife Service)
404-679-7292
tom_mackenzie@fws.gov

The performance of Wolf Creek's barrier wall completed on March 6, 2013 continues to meet expectations.  All of the quality control data collected during construction of the wall shows that it meets or exceeds all of its design standards.  As a result, the lake was raised approximately 20 feet after completion of the wall and we will continue to operate under the relaxed restrictions.  We continue to monitor the instrumentation and daily readings of the heavily instrumented dam are responding as expected.  We also are continuing our daily visual inspections.  Wet areas downstream of the dam are being monitored on a daily basis and most generally show improvement though some still persist.  The condition of these is influenced by rainfall and natural groundwater levels and the unusually wet spring and summer have kept some areas wet.  However we see nothing that gives us concern and are confident the wall has sealed areas that posed a threat to the dam.

If the dam continues to perform as it has during this incremental pool raise and after another safety review, the goal is to return the lake to its historical operating levels next spring.  The lake is expected to be operated in its normal range in the fall of 2013 and could be lowered to elevation 685 feet as part of the normal water management cycle and to facilitate final riprap placement on the upstream face of the earthen portion of the dam.   This final riprap placement and removal of the remainder of shot rock fill off the upstream slope of the dam should commence by late summer.

Also commencing by late summer will be the construction of a short barrier wall below the dam in the switchyard and powerhouse area.  The purpose of this wall is to extend a previous barrier wall and to prevent water intrusion from the fluctuating river below dam into the switchyard area.  It is believed that the fluctuating water is removing material from the switchyard area and this wall extension will block this flow path. 

The overall Wolf Creek Dam Safety project is 91 percent complete and all construction activities are scheduled for completion by September 2014.

• Barrier wall construction continues and remains on schedule to be completed in December 2013 with the intention of raising the pool in increments for the 2014 recreation season upon its completion. An independent assessment of quality control data and a re-evaluation of the structure’s Dam Safety Action Classification will ensure a tolerable risk level has been achieved once construction is finished.
• The total project cost estimate has been raised to $594 million primarily due to delays associated with the work suspension in Critical Area 1 from March to November 2010. In Mar 2010, the Great Lakes and Ohio River Divi-sion commander directed a suspension of work in Critical Area 1 due to potential embankment instability in the wrap-around section.
• Foundation Remediation Contractor Treviicos Soletanche JV (TSJV) completed the Protective Concrete Embankment Wall on June 19, 2012—protecting the entire earth em-bankment.
• To date, TSJV has completed approximately 92 percent of the Pile Barrier Wall, and 100 percent of the pilot holes.
• The Judy Company completed drilling and grouting in the switchyard plaza in July 2012. Results of the grouting pro-gram were used to analyze the need for additional meas-ures in this area. A subsurface barrier wall to supplement the wall constructed in the plaza area in 1979 is planned.

• Barrier wall construction continues and remains on sched-ule to be completed in December 2013 with the intention of raising the pool for the 2014 recreation season upon its completion. An independent assessment of quality control data and a re-evaluation of the structure’s Dam Safety Ac-tion Classification will ensure a tolerable risk level has been achieved once construction is finished.
• The total project cost estimate has been raised to $594 million primarily due to delays associated with the work suspension in Critical Area 1 from March to November 2010. In Mar 2010, the Great Lakes and Ohio River Divi-sion commander directed a suspension of work in Critical Area 1 due to potential embankment instability in the wrap-around section.
• Foundation Remediation Contractor Treviicos Soletanche JV (TSJV) completed the Protective Concrete Embankment Wall on June 19, 2012—protecting the entire earth em-bankment.
• To date, TSJV has completed approximately 80 percent of the Pile Barrier Wall, and 98 percent of the pilot holes.
• The Judy Company completed drilling and grouting in the switchyard plaza in July 2012. Results of the grouting pro-gram are being used to evaluate the switchyard area for possible future mitigation efforts.

• Barrier wall construction continues and remains on sched-ule to be completed in December 2013 with the intention of raising the pool for the 2014 recreation season. An in-dependent assessment of quality control data and a re-evaluation of the structure’s Dam Safety Action Classifica-tion will ensure a tolerable risk level has been achieved once construction is finished.
• The total project cost estimate has been raised to $594 million primarily due to delays associated with the work suspension in Critical Area 1 from March to November 2010. In Mar 2010, the Great Lakes and Ohio River Divi-sion commander directed a suspension of work in Critical Area 1 due to potential embankment instability in the wrap-around section.
• Foundation Remediation Contractor Treviicos Sole-tanche JV (TSJV) has completed 64 percent of the Protec-tive Concrete Embankment Wall in Critical Area 1. When the final 16 panels are completed, the entire embankment will be protected.
• To date, TSJV has completed approximately 66 percent of the Pile Barrier Wall, 73 percent of the Combined Barrier Wall, and 88 percent of the pilot holes.
• The Judy Company continued drilling and grouting in the switchyard plaza. Zones of no recovery were encountered in the vicinity of the sinkholes that formed in the late 1960s. An exploratory drilling and geophysical program to define and treat those features has been negotiated with the con-tractor and results are expected by June 4, 2012.

• Project construction is expected to be completed in December 2013 with the intention of raising the pool for the 2014 recreation season. The pool raise is dependent on the final risk assessment and evaluation to revise the structure’s Dam Safety Action Classification.
• Foundation Remediation Contractor Treviicos Soletanche JV (TSJV) has completed raising and wid-ening the work platform in Critical Area 1. The platform slab as well as the guide wall have been installed.
• On Feb. 15, TSJV successfully completed excavation of the first Protective Concrete Embankment Wall (PCEW) panel in the cave and core trench section of Critical Area 1.
• To date, TSJV has completed approximately 91 percent of Protective Concrete Embankment Wall, 41 percent of the Pile Barrier Wall, 55 percent of the Combined Barrier Wall, and 83 percent of the pilot holes.
• The Judy Company continued drilling and grouting in the gallery and plaza. The grouting program has confirmed a hydraulic link between the tail water and piezometers on the downstream embankment. Additional holes will be drilled in the plaza to precisely locate and treat those features.
• Work continues six days a week, 24 hours a day.