Working in conjunction with Advitam of France on a project for the EDF Energy R&D section
in the French Pyrenees, we installed a long-range hydrophone system for recording low- pressure, high-volume leaks in the 9’ diameter Hydro-Electric plant bulk water transfer tunnel.
The hydrophone, which was the first of its kind, could transmit the live audio data through 3km of cable. We designed a food-grade dye dispersant system that could be remotely actuated in the vicinity of a leak to enable the path of the leak to be assessed both visually and acoustically.
The hydrophone and dye dispersant system was mounted on a remote manipulator arm positioned on the front of a bespoke Pipe Inspection Vehicle (PIV) with a 3km excursion range.
The subterranean tunnel access chamber was located at around 3500’ in the Nantilla mountain range and around 4.5 tonne of plant and equipment had to be transported up a steep and winding gravel track to reach the access chamber. The tunnel was accessed via a 60m deep shaft with a 2m x 2m restriction below water level that the PIV had to negotiate before it could enter the tunnel.
The survey successfully located a high-volume leak that significantly exceed expectations on a location that the client had not anticipated, this leak alone created a stream that had run through the local village for many years. The project was a success and we are currently developing a hydrophone capable of detecting low-pressure, high-volume leaks via fibre optic cabling.