NASHVILLE DISTRICT

The U.S. Army Corps of Engineers Nashville District awarded a $42,972,545 contract June 27, 2016 to Thalle Construction Co., to build a concrete reinforcing berm downstream of the Center Hill Auxiliary Dam.  The work also includes stabilization of a previous rock cut near the main dam.

The main components of work in the auxiliary dam contract awarded are:

• A 130,000 cubic yard roller compacted concrete reinforcing berm immediately downstream of the saddle dam

• Excavation and stabilization of the cut slopes east of the main dam in the area commonly known as the left rim with transport of excavated material to be placed between the existing auxiliary dam and the newly constructed RCC berm

While the contract will complete the auxiliary dam rehabilitation, the first two major contracts addressed seepage issues at the main dam.  The 2008-2010 work included grouting at the main dam and left rim.  To complete the main dam improvements, a 2012-2015 foundation barrier wall was then installed through the main dam earthen embankment and deep into foundation rock.  

State highway 96/141 across the dam is planned to remain open, as well as Long Branch Campground downstream of the dam, throughout the two and one-half year contract. 

In addition to this major contract, there will be several small contracts required for site restoration through 2019. 

 

Final concrete placements complete Center Hill Dam barrier wall

LANCASTER, Tenn. (March 17, 2015) – The U.S. Army Corps of Engineers Nashville District is placing the final concrete to complete a barrier wall in the main dam embankment of Center Hill Dam this week. These concrete pours complete the $115 million foundation barrier wall, a key component of the Center Hill Dam Safety Remediation Project.

“The barrier wall provides a permanent ‘barrier’ to potentially harmful seepage beneath the main dam earthen embankment,” said Linda Adcock, project manager. “Completion of this phase of the project significantly increases the safety of the dam.”

Adcock explained that the concrete barrier wall is approximately 2.5-feet thick constructed vertically along the embankment in overlapping rectangular columns as deep as 308 feet from the top of the dam and deep into the solid-rock foundation.

Bauer Foundation Corporation performed the work to protect the earthen portion of Center Hill Dam. The “first bite” of a giant auger drill rig turned up the first dirt of the project July 11, 2012.

This is the second of three contracts to remediate the Center Hill project. The third and final contract expected to be awarded later this year involves the installation of a concrete berm downstream of the auxiliary dam embankment. The auxiliary dam is a secondary earthen embankment that fills a low area in the landscape just east of the main dam.

The lake levels continue to be operated between elevation 630 feet above mean seal level in the summer and no lower than elevation 618 MSL during the late fall and early winter.

Center Hill Dam is rated in the Corps’ “Dam Safety Action Classification I,” which is the most urgent category for Dam Safety modification in the Corps. Even though the concrete barrier wall is complete, the classification of the dam cannot be changed until the third and final contract is completed, the remediation works are assessed and the project is reclassified. The final reviews are expected to be completed in 2018; the lake level is expected to be raised in time for the summer recreation season.

(The public can obtain news, updates and information from the U.S. Army Corps of Engineers Nashville District on the district’s website at www.lrn.usace.army.mil, on Facebook at http://www.facebook.com/nashvillecorps and on Twitter at http://www.twitter.com/nashvillecorps.)

Center Hill Dam rehabilitation continues with barrier wall installation

LANCASTER, Tenn. (Feb. 14, 2014) - The U.S. Army Corps of Engineers Nashville District’s ongoing foundation rehabilitation project at Center Hill Dam is making progress as work crews continue to drill deep into the main dam earthen embankment to install a subsurface concrete wall. The current efforts are the second of three major contracts from 2008 to 2017 that comprise ongoing efforts to rehabilitate Center Hill Dam.

According to construction resident engineer Bill Debruyn, the problems stem from the karst limestone foundation and from the standard foundation preparation practices of the early 1940’s. The foundations of the two large earthen embankments, the main dam and a smaller saddle dam, are the focus of the multi-year project. The goal is to prevent foundation seepage from potentially harming the embankments.

Today’s technology makes it possible for work crews to make the necessary repairs deep in the foundation.

“Construction is going very well and the weather is cooperating with no major delays,” said Debruyn.

Despite the arrival of cold weather and bone-chilling temperatures, workers from the Bauer Foundation Corporation are making strides at the project site located in Lancaster, Tenn., on the Caney Fork River.

According to Debruyn, an encasement concrete wall, the first major structure, is near completion. The encasement wall is made of 10’x6’ overlapping rectangular columns into the earthen portion of the dam down to the rock foundation.

“Bauer is using custom built state-of-the-art equipment to excavate vertical columns, held open with continuously circulating slurry mix,” said Debruyn. Made primarily of clay and water the slurry not only supports the hole but transports the cuttings to the surface for removal. The slurry in each encasement wall column is then replaced with concrete. The columns overlap to form a long continuous concrete wall which protects the earthen embankment while the smaller and deeper barrier wall is similarly constructed.

“Beginning in March the barrier wall will be built through the encasement wall up to three hundred feet below the top of the dam through the karst rock ending in the solid rock layers,” said Center Hill project manager Linda Adcock.

Adcock said the barrier wall is a permanent seepage barrier and is planned to be completed in the summer of 2015.

A report is undergoing final approvals to implement the best repair plan for the earthen saddle dam. A concrete berm is planned downstream of the saddle dam from 2015 to 2017 as the final major rehabilitation phase of construction.

The Corps currently manages Center Hill Lake levels targeting a summer high of 630 feet above mean sea level and a winter pool of about 620 feet; however, day to day lake levels are highly dependent on the weather. These target elevations are 10-15 feet lower than normal and are part of risk management until the repairs are complete in late 2017.

Center Hill Dam is one of the multipurpose projects that make up the Corps of Engineers’ system for development of the water resources of the Cumberland River Basin. This system is an important part of a larger plan of development for the Ohio and Mississippi Rivers. The dam controls the runoff from a drainage area of 2,174 square miles.

As a major unit in the system, Center Hill Dam and Lake function to control the floodwaters of the Caney Fork River and contribute to the reduction of flood levels at municipal, industrial and agricultural areas along the Cumberland, lower Ohio and Mississippi Rivers.

Highway 96/141 which routes traffic over Center Hill Dam is a heavily traveled road and is now restricted to one lane. The restriction is required to support the construction on the project and installation of the foundation barrier wall. During the two-year duration of construction at the site, one lane of Highway 96 will be closed and an automated traffic control system will safely manage vehicles across the dam. Debruyn said the maximum expected wait time is five minutes.

To read more on Center Hill Dam, the seepage problem, the fix and project updates visit the Nashville District webpage at http://www.lrn.usace.army.mil/CenterHill. For more information about the U.S. Army Corps of Engineers Nashville District, visit the district’s website at www.lrn.usace.army.mil, on Facebook for updates at http://www.facebook.com/nashvillecorps and http://www.facebook.com/centerhilllake, and on Twitter at http://www.twitter.com/nashvillecorps.

U.S. Army Corps of Engineers awards Center Hill Dam barrier wall construction contract

NASHVILLE, Tenn. (Sept. 22, 2011) — The U.S. Army Corps of Engineers, Nashville District announced today the award of a $106 million contract to Bauer Foundation Corporation to install a barrier wall at Center Hill Dam, which was officially awarded late yesterday.

To see the Federal Business Opportunities contract award announcement for this project click here.

"This important construction will provide a barrier to protect the earthen portion of the main dam from seepage problems. The barrier will significantly improve the long-term reliability of the dam and public safety" said Project Manager Linda Adcock.

Most of the construction will be accomplished below ground and requires specialized equipment as well as close monitoring.

The main components of work are:

• Enlarge a work surface along the upstream (lake) side of the main dam earthen embankment

• Construct approximately 200,000 square feet of concrete panels and columns in two phases through the embankment extending downward 120 feet into foundation rock to form a minimum 2-foot thick continuous barrier wall

Highway 96 across the dam is planned to remain open, as well as Long Branch Campground downstream of the dam, throughout the two and one-half year contract. The Center Hill Dam has been identified by the Army Corps of Engineers as a high risk dam due to foundation seepage. A 2008-2010 grouting contract was an important first step to reduce the seepage and to prepare the foundation for construction of the barrier wall.

"We are currently studying the appropriate improvements for the saddle dam, a smaller earthen dam northeast of the main dam" Adcock said.

The saddle dam work will be the third large contract. A final small contract will be required for site restoration.

In December 2010, the first important phase of the rehabilitation, foundation grouting, was completed. IN this three-year construction contract, more than 50 miles of drilling of small holes was completed in order to pump over 1.5 million gallons of grout (which is a concrete mixture) into the rock foundation to make it stronger. Water moving through the foundation has been decreased and the dam is safer now than before the work was done.

The process of selecting a contractor is currently underway for the next contract to construct a concrete barrier wall from the top of the dam 300 feet down through the earthen embankment and into the rock foundation. This is highly specialized work to safely and effectively construct this barrier wall. We antici-pate awarding this construction contract in September 2011 and equipment to begin arriving near the end of the year. The contract will continue until mid 2014.