TVA takes reactive and proactive steps to protect dams from earthquakes
Last week's magnitude 4.4 earthquake was one of the four largest historical earthquakes to hit the East Tennessee Seismic Zone, dating back to 1844.
The earthquake caused no issues for TVA's dams, which are designed to withstand even larger earthquakes.
Following the earthquake, all hands were on deck including inspectors, engineers, plant staff and field technicians. TVA inspected 22 dams within 24 hours to confirm that no damage was caused. Nineteen of those inspections were Level 3, their lowest priority level, including the Chickamauga Dam in Chattanooga.
"Watts Bar did have a higher level since it was so close. It did have what we call a Level 1 inspection, which is a little more comprehensive," Kristen Smith, TVA Senior Program Manager of Dam Safety, said.
For future events, if any damage is found, each situation is treated as a case by case basis to investigate further or repair as necessary.
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"In addition to responding to an event, whether it is a flood or an earthquake, not only are we reactive, but we are proactive. We have normal routine inspections. We have routine instrument readings," Smith explained.
These proactive inspections include monthly ones and intermediate inspections performed every 15 months. Every five years, more in-depth formal inspections are completed.
"We get a team of subject matter experts, geotechs, structures, hydrology and hydraulics. All of these team members come in. We review all of our information, and we walk down every square inch of the dams," Smith said.
The inspections are integral to TVA's process to ensure all dams are stable and equipped to withstand earthquakes and other events.
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Additionally, they perform risk assessments and constantly update with new information and probabilities. They have emergency action plans for all dams and work with TEMA, FEMA and local county EMAs.
"We practice. We have exercises of different scenarios," Smith added. "If this happened at a dam, what would we all do? You know, what would we do to protect the dam? What would they do to protect their citizens?"
All of TVA's procedures are to guarantee that they are prepared as best as they can be for future events.
Smith said they will take lessons learned from this event to improve communications and responses for the future.
Additionally, TVA does have a plan to place seismic monitors at all dams. Monitors were recently installed at the Chickamauga Dam due to the blasting at the lock construction site.