Following a global search for a capable pipe inspection company, we were commissioned by the Environment Agency, Black & Veatch and Jackson Civils to inspect a 21km x 2.5m diameter bulk water transfer tunnel. There were only 3 useable access shafts, which varied in depth between 35m and 85m, with 1800mm square covers and a 10m drop to water level. The distance between the hatches varied between 3000m to 12400m. Duty pumping had to be maintained throughout the survey.
Our scope was to carry out a live visual/CCTV tunnel inspection to provide a full circumferential view of the pipe to facilitate pipe condition assessment which had to including hairline cracks, concrete segment displacement and tunnel ovality using profiling sonar. It was essential that recorded CCTV data had full resolution on playback with the capability of viewing key areas in fast forward, slow motion, with seamless pause, picture enlargement where required and the capability to screen dump specific images.
With no-proprietary equipment available we set about designing and building a self-propelled Pipe Inspection Vehicle (PIV), with an 11-camera configuration and profiling sonar, which was controlled and monitored via 10km of neutrally buoyant Micro-Fibre Optic cable, all within a 4-month window.