The Tennessee Valley Authority's Blue Ridge Dam began generating electricity again on Monday, July 11, after a year-long repair project on the large pipe, known as the penstock, that carries water from the reservoir to the turbines in the powerhouse.
The rehabilitation work, to meet more rigorous safety standards, began in July 2010 with the drawdown of the reservoir. The reservoir is now about 6 feet below summer levels after being as low as 65 feet below normal levels over the past year.
The project had three components: installing a new liner in the penstock, stabilizing the water intake tower above the dam and adding rock to the upstream and downstream faces of the dam.
The first phase, installing 500 feet of the 1,000 feet of steel liner in the penstock, was completed on March 24 and allowed the reservoir to begin refilling.
The new liner repaired damage to the penstock that occurred in 1931 when the reservoir was filled after the dam was completed.
In the second phase, TVA drilled 60-foot holes to secure six multi-strand anchors in the bedrock beneath the water intake tower to ensure it can withstand an extreme earthquake. That work was completed May 31.
The third phase to add rock to stabilize and strengthen the dam is partially complete. TVA has finished the rock placement on the upstream face of the dam and is now working on the downstream face. This work is expected to be finished in summer 2012.
A dissolved oxygen system, which allows oxygen to be injected into the reservoir to improve downstream water quality, also has been replaced. The system helps support a thriving trout population.
"Performing this work in three phases allows us to refill the reservoir and add oxygen to the water at the same time we finish the work, benefitting fishermen and boaters," said John McCormick, TVA's senior vice president of River Operations.