GRAY, Tenn. — The Tennessee Valley Authority today announced a proposed repair project to correct water seepage and erosion at the earthen embankment portion of Boone Dam, located near Gray, Tenn.

Pending a formal environmental review, TVA engineers and other dam safety experts are recommending the construction of a composite seepage barrier – a multi-stage combination of grout injections and concrete – inside the earthen embankment. Project completion estimates range from five years to up to seven years. The initial cost estimate of the repair is expected to be between $200 and $300 million.

“We realize the impact this will have on those who live and work in neighboring communities, but our overriding focus must always be the safety of our workers and the public. Lowering the lake was a prudent first step, and it's one we'll continue for safety's sake until further remedial work is completed,” said Bill Johnson, TVA president and CEO. “We will do whatever it takes to correct this issue and allow the public to safely enjoy the lake. Boone Dam and reservoir are important assets for TVA and the people of this region, and we're committed to preserving them for generations to come.”

After seepage under the embankment was discovered in October 2014, a thorough investigation discovered a complex series of underground geological pathways allowing water from both upstream and downstream sources to cause internal erosion. If left uncorrected, the erosion could eventually lead to the failure of the dam.

“The proposed composite seepage barrier should prevent further erosion and we are confident will provide the most robust, long-lasting repair at Boone Dam,” said John McCormick, TVA vice president of Safety, River Management and Environment.

Preliminary testing and site preparation work is already underway. In addition, TVA is proceeding with plans to improve boat and public access to Boone Reservoir, improve the safety of boaters during the lower water levels, assist marina owners most seriously affected and maintain a healthy fishing habitat

The public will have the opportunity to comment on the proposal during a formal environmental review process scheduled for later this year, as well as during public meetings in the community, the next of which is today at 5:30 p.m. at the Millennium Centre in Johnson City, Tenn.

Additional details of the proposed repair and the latest updates on the ongoing project are available at www.tva.gov/boonedrawdown. TVA has also launched a new Twitter feed — @BooneRepair — dedicated to the Boone Dam repair project.

The Tennessee Valley Authority is a corporate agency of the United States that provides electricity for business customers and local power distributors serving 9 million people in parts of seven southeastern states. TVA receives no taxpayer funding, deriving virtually all of its revenues from sales of electricity. In addition to operating and investing its revenues in its electric system, TVA provides flood control, navigation and land management for the Tennessee River system and assists local power companies and state and local governments with economic development and job creation.