Blue Ridge Dam Rehabilitation

July 29, 2010

Recent view of the construction site on the downstream face of the dam, showing the diversion system for stormwater flow, the access road for installing the dewatering system, and the drill rig used to drill the wells needed for the dewatering system.

Progress to date

• TVA began a deep drawdown of Blue Ridge Reservoir on July 15. The reservoir will be lowered gradually to an elevation between 1620 and 1630 feet above sea level by November.  The deep drawdown is necessary to protect the penstock and ensure the safety of the workers who will begin repairing the penstock this fall.
• The contractors hired by TVA to work on the project have been mobilized.  Approximately 15 people, including both TVA and contract personnel, are working on the site daily.
• Measures are in place to reduce erosion and sedimentation at the construction site, including installation of over 1,700 feet of silt fencing, placement of 1,100 feet of Erosion Eels (10-foot long tubes designed to remove sediment from stormwater runoff), and construction of a diversion drain on the downstream face of the dam.
• Construction of a dewatering system is nearly complete. This system, which consists of drilled wells, pipes, and water pumps, will help relieve pressure around the penstock, stabilize the downstream face of the dam near the penstock excavation, and control the flow of groundwater.

Upcoming

• TVA will continue to draw Blue Ridge Reservoir down at a rate of approximately seven feet a week for the next two to three weeks. After two to three weeks, the rate will slow to three feet a week.  The slow, controlled rate of drawdown is necessary for the safety of the dam.
• A portion of Old Highway 76 at Blue Ridge Dam will be closed beginning August 1 through the end of the project.  The closure is necessary to protect the public from the heavy equipment in the area and to protect construction workers from traffic.

Project overview

Safety is the number one job at TVA: the safety for the public surrounding TVA lands and lakes, and the safety of TVA employees. To help ensure the safety of the people of Blue Ridge and in downstream areas and to meet more rigorous dam safety standards, TVA is performing a rehabilitation project expected to last from mid-July 2010 to 2012.

The rehabilitation project at Blue Ridge Dam consists of three components:

• The penstock, the underwater pipe that carries water from the reservoir to the turbines in the powerhouse, was damaged when the reservoir was refilled after construction in 1931.
• TVA will install a new liner in the penstock to repair it. The intake tower will be stabilized at its base.
• The upstream and downstream faces of the dam will be stabilized.

To safely install the lining in the penstock, TVA will draw down the level of the lake beginning in mid-July 2010 and will hold the elevation about 68 feet lower than the usual summer elevation for about six months. Following completion of the penstock repair, the refilling of the reservoir will be contingent on the Spring rains in 2011. Completing the penstock repair should do away with the deep drawdowns currently required every five years for inspection of the penstock.

Drawdown timetable