Guernsey Public Utilities


Project: Guernsey Public Utilities

Scope: Condition assessment on cast iron mains

Location: Belle Greve and Red Lion outfalls

The work was carried out in conjunction with AES, our partnering company at the time and the chosen NDT discipline was Magnetic Flux Leakage (MFL), to locate and measure pin holing, graphitisation levels and thickness of remaining material on surface run pipes, submerged riser and submerged pipe section.

A Cygnus diver held ultrasonic wall thickness probe and MFL system was designed specifically for the project and was used by our divers working within a flooded shaft to assess the condition of the riser; the probe was subsequently mounted on a medium range PIV to assess the condition of the pipe sections running within the flooded tunnel.

To meet specific requirements, we modified one of our ultrasonic wall thickness probes to measure plastic pipe wall and designed and built a remote manipulator arm and cleaning head to fit one of our small diameter PIV’s to facilitate the inspection and testing of a 400m long plastic pipe section that had been installed to extend the existing outfall.

The PIV was launched into the outfall by our dive team and the control cable tended by a diver throughout the survey.
The project was entirely successful and provided the Client with the level of information they required for future planning of outfall remedial programme.

Testimonial: They were recommended by Black & Veatch, our Consulting engineers for the Belle Greve project, as the ideal people for the job. Site conditions resulted in the project protracting and PSD’s requirements evolving; WSG provided a timely solution for every problem that we encountered on the project even to the point of modifying some testing equipment to measure the wall thickness of a section of HDPE pipe. They provided us with total client support at every stage of the project.

Colin Gaudion – Senior project advisor – PSD Guernsey