St Sampsons Harbour Guernsey Pipeline Assessment

The Challenge

In March of 2024 WRc was asked to undertake a condition assessment of the cross harbour fire main link at St Sampson's Harbour in Guernsey to ascertain the location and size of a known leak. The fire main crosses the harbour foreshore so the survey programme had to be carefully timed to correspond with a Neap Tide to enable pedestrian access to the pipeline route.

The Solution

WRc employed the Sahara Pipeline Inspection System with an Acoustic survey head. Using an induced flow from a fire hydrant we surveyed from a chamber on the South side of the Harbour across the harbour foreshore to the Tee into the fire main ring on the North side.

A plan was provided with timings to hit deadlines for low tide foreshore access and recommissioning of the fire main for the arrival of the fuel tanker. During an eight hour window the schedule involved:

• Isolate the fire main from the pumps and depressurise
• Sahara Pipeline Inspection System with Acoustic survey head inserted
• Fire main re-pressurised
• Flow induced
• Survey undertaken to coincide with low tide at 14:23 to allow tracking
• Leak identified and marked up
• Survey equipment retrieved and extracted
• Fire main put back in service

The Results

The survey achieved the full distance between the two chambers either side of the harbour.

Two leaks were identified, a medium leak close to the harbour wall and another very small leak close to a location where the main was known to have been pieced together during its construction. Both were located and their positions recorded.

All of the timelines in the schedule were hit and the fire main was back in service ready for the arrival of the next fuel delivery.

WRc is a great team to work with, they provide the perfect solution for the brief and timescale, I would highly recommend WRc to anyone in the industry that needed this type of specialist survey. - Martin Lucas - Head of Operations Guernsey Fire & Rescue Service