Hydroelectric dams are impressive in both size and scale. Some of the tallest dams stretch over 300 meters tall and the longest dams span nearly 4 miles wide. The single largest reservoir in the world holds 180 cubic kilometers of water, which is roughly 47 trillion gallons, enough to provide the entire United States with water for nearly five months! It’s no wonder that hydro power accounts for 20% of the world’s energy. With such large structures comes a serious need for underwater inspections and preventative maintenance. Inspection class Remotely Operated Vehicles (ROVs) offer a great deal of support for routine dam inspections, including inspecting Face of Dam, Heel and Toe of Dam, Water Intakes, Trash Racks, Penstocks, Turbines, and Lower Outlets.
nDams provide a set of unique challenges for inspection. It’s a dangerous environment, with deep water, fast moving water, turbid outflows, turbines and other entanglements. It’s extremely dangerous and sometimes impossible for divers to inspect these areas while the dam is operational. Only ROVs with the most hydrodynamic design and highest levels of thrust can overcome the demands of dam inspections. Typically, an AC power system is required to keep the vehicle in continuous operation for long shifts or for heavy thruster use to counteract the current, which would otherwise deplete a DC battery system.
ROVs come equipped with a variety of sensors which are extremely helpful for dam inspections. Features such as HD Cameras, High Intensity LED Lights, Sonar, Laser Scaler, Thickness Gauge and Grabber Arm are used heavily. The Camera paired with LED Lights are used for visual inspection and documentation, and are especially useful in deep, dark waters along the bottom of the dam. Sonar is a critical tool for successful navigation in very turbid water where water clarity is minimal. A Laser Scaler emits two lasers at a fixed width, acting like a measuring stick, allowing for accurate measurement of objects by simply looking at them with an ROV. A Non-destructive thickness gauge is used to check the integrity of coatings and measuring corrosion. And a grabber arm can be used to clean trash racks of debris, or to retrieve foreign objects from the water around a dam.
By utilizing inspection class ROVs for dam inspections it eliminates the risk to divers, reduces the down time of dam operations, provides the ability to increase the frequency of inspections and perform preventative maintenance faster while reducing the per-inspection cost.