Subaquatic inspections of EDF (Electricite de France) dams

EDF controls more than 150 high dams (more than 20 m in height). It is a legal requirement to inspect them while they are being emptied every ten years. In order to limit the negative effects on the local environment and to reduce the lost of production, this emptying can be replaced with a remotely operated vehicle (ROV) inspection which would give a clear view of the portion of the dam underwater. During the last 18 months, EDF and COMEX company have considerably improved the inspection´s procedure by ROV by: the use of a Super Achille ROV with a mechanical arm; the measurement of the dimensions of the defaults with a SMC process as well as a laser; the positioning of the ROV by an acoustic signal system; the positioning of the defaults on a layout of the upstream part of the dam; the ability to draw up the report at the same time as the inspection by a specialized civil engineer; and the measurement of the water´s turbidity before each inspection. Inspection carried out on the Laouzas´ dam in September 1999 is a good representation of these new improvements. EDF´s objective for the future is to achieve all inspections by ROV