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Making Boone Better

Why is Boone Lake so low?

"While safety is the most important factor — making this drawdown the right decision—we understand the impacts of extended low lake levels on local businesses and residents, making this drawdown a difficult decision"

—John McCormick
VP Safety, River Management and Environment

In October 2014, TVA’s Boone Dam employees discovered a sinkhole along the earthen embankment near the base of Boone Dam. This sinkhole was repaired, but then TVA inspectors discovered sediment and water seeping from the river bank just below the dam. Because water and sediment seeping from the area is not common and can be a sign of more serious issues, as a safety measure, TVA quickly accelerated its winter drawdown and lowered the level of Boone Lake to about 10 feet below normal winter pool levels to reduce pressure on the dam.

In early February 2015, TVA, in consultation with other dam safety experts, met to help quantify risks, confirm analyses and guide its actions. After that meeting, TVA announced that Boone Lake will not be returned to normal operating levels until the source of the seepage can be identified, and a solution can be implemented.

 

What is the current status of the dam?

Safety of the public and our employees is TVA’s top priority. TVA is continuously monitoring Boone Dam to identify any changes in its condition. This monitoring and assessment data indicate the dam is not in any immediate danger and is structurally sound. However, recent investigations indicate that, under normal lake levels, erosion may be occurring deep beneath the dam’s earthen portions and, if not repaired, could worsen and threaten the stability of the dam’s earthen areas.

What work has been done at Boone?

TVA continues to monitor the dam closely, investigate the seepage of sediment and water, take preliminary actions, and work to determine the best permanent repair option. Work will be reviewed by an independent board of national dam safety experts.

Based on the location of the initial sinkhole and later seepage, TVA is focusing its investigation on the earthen embankment area of the dam. As part of this investigation, employees have identified seepage paths deep beneath the embankment. If left “as is,” erosion of this embankment could worsen and threaten stability of the earthen portions of the dam.

Here are a few completed and ongoing actions:

  • Filled and repaired initial sinkhole along earthen embankment
  • Installed advanced instrumentation
  • Placed temporary filter along the riverbank near Boone Dam’s Unit 1 to help control soil erosion and to capture sediment
  • Deployed an unmanned, remotely-operated submarine (with sonar technology) to assess underwater conditions 
  • Drilled core samples to study earthen embankment and foundation conditions
  • Used radar and geophysical instruments to determine underground and underwater conditions
  • Collaborating with industry experts from around the world to thoroughly analyze the situation
  • Placing safety buoys in designated areas of Boone Lake
  • Using laser to monitor earthen embankment stability

What is TVA’s next step?

Work is expected to begin soon to stabilize conditions of the earthen embankment area of the dam by injecting grout into the soil and rock at the embankment. However, this interim grouting step is only part of the overall process while TVA employees continue to analyze the situation to determine the best permanent repair option.

Have other dams faced a similar issue?

Yes. Sediment seepage is an uncommon, but not unheard of occurrence. At other dams that have experienced seepage in the past, the source has been identified and the dams have been successfully repaired. These dams include TVA’s Tims Ford Dam (Tenn) and Little Bear Creek Dam (Ala); the U.S. Army Corps of Engineers’ Wolf Creek Dam (Ky), which completed repairs for this type problem in 2013; and Center Hill Dam (Tenn), which is near completion.

What would happen if the dam failed?

Though it is highly unlikely, TVA has worked with counties, states, the National Weather Service and a host of other partners to prepare for such an event. If surveillance or instrumentation ever signaled an impending dam failure, TVA has Emergency Action Plans (EAPs) in place and would immediately notify affected counties to begin evacuations and the National Weather Service to broadcast a Dam Failure Flood Warning to the public.

What other lakes are near Boone Lake?

There are several lakes near Boone offering plenty of alternative recreation opportunities. Find out more with this interactive map

 

Read more about Boone Dam

 

 

 

 

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