Time was, dam safety inspections meant climbing, crawling and diving. Today—thanks to some nifty new technology—it means simply boating and monitoring.
Side-scan sonar—a new state-of-the-art technology—can take 2D and 3D images of dams from a boat-mounted device to identify potential maintenance issues in real time. The system has the capability to rotate 360 degrees and tilt plus or minus 45 degrees to provide a wide range of perspectives.
“This system allows us to see the dams more effectively and efficiently, and improves our ability to conduct dam safety inspections,” said Scott Kramer, TVA manager of Dam Safety Inspections. “These inspections help us identify any potential problems before they can become serious issues.”
The side-scan sonar images (see below) allow TVA engineers and inspectors to assess the condition of dams, view underwater contour features and conduct detailed inspections.
The sonar system can be deployed quickly from a tripod or mounted to the side of a boat, enabling inspections that would have taken divers a week to complete to be conducted in a single day. With the 3D sonar head, the setup also allows for the integration of GPS technology for real time mapping, scanning and hydrographic surveying.
“The sonar is a great addition to our program and provides real benefits to our dam safety inspections,” said Benjamin Phillips, a civil engineer for TVA’s Dam Safety Inspections team. “We are able to look at the entire facility, whereas with divers, you’re really only able to look at what you can reach.”
The side-scan sonar system also saves money. Inspections can be conducted while turbines are running and power is being generated, whereas traditional methods with divers require generation to be stopped, resulting in lost power costs.
With safety of employees and the public as its top priority, TVA’s Dam Safety team and independent structural experts work to ensure that TVA’s 49 river dams—including many earthen structures—conform to federal design, operation, maintenance and repair guidelines.
TVA inspects its hydro facilities monthly, biannually and annually to look for signs of erosion or any other issues that may cause concern.
These inspections are part of a robust, comprehensive Dam Safety program that also includes continuous electronic monitoring for vibrations; rigorous structural and geological assessments; and surveillance not only of the surface of hydro structures, but also the geology under and around the dams.