The Tennessee Valley Authority is accelerating the annual drawdown of the reservoir of 160-MW Pickwick Landing Dam in the Southeast United States for a dam safety seismic study.
TVA said Sept. 10 that initial results from testing and core drilling suggest a remote chance that the earthen embankment south of the concrete portion of the dam could be damaged by a large earthquake. Pickwick Landing, in west Tennessee, northeast Mississippi and northwest Alabama, is a few hundred miles from the New Madrid Seismic Zone along the Mississippi River.
TVA began "health checks" of its 49 dams more than a year ago as part of a continuous improvement program. The study checks the integrity of the concrete and earthen embankments against today's stringent industry standards.
Lower lake levels at Pickwick Landing will allow TVA to conduct more detailed analysis and testing over the next several months to determine what would be necessary to strengthen the south embankment against large seismic events.
"Public safety is our top priority," TVA Vice President of River Operations John McCormick said. "Because large earthquakes can't be predicted, we're taking immediate action to enhance the continued safety of the public and our employees."
Pickwick Landing Reservoir levels are expected to reach winter pool by mid-October, which is about six weeks earlier than normal. Water levels downstream of Pickwick Landing Dam on Kentucky Reservoir will not be affected, TVA said.
Pickwick Landing Dam was designed and built in the 1930s. The concrete portion includes the powerhouse, spillways and two navigation locks with long earthen embankments on each side. The south embankment is about 4,000 feet long.
TVA said last year it averted more than $800 million in flood damages to communities along the Tennessee River and its tributaries through its dam management programs in January 2013.