Twaite Shad in the River Usk

Vibrock’s consultants have been involved in several long-term projects, one of which involved noise and vibration monitoring during the installation of a 40 kilometre long pipeline. The 1.2 metre diameter pipe crosses 38 roads, 5 railways, 2 motorways and 2 canals. The pipe traverses a diverse range of countryside, from open fields to areas of dense residential property. The work has involved 7 days per week working, sometimes 24 hours per day, for 10 months.

The Twaite Shad is one of Britain’s most endangered fish, so no surprise that concern was expressed over plans to install a pipeline across the River Usk, one of the last strongholds of this fish within the UK. It was feared that ground vibration from the intended horizontal directional drilling (HDD) technique intended for use at the river crossing, might be sufficient to disturb the Shad in its breeding grounds along the reed beds of the River Usk. Hence there was a need to monitor vibration levels from a similar operation which was being undertaken under the River Orwell at Ipswich.

Measurements, using a number of Vibrock V801 seismographs, were obtained from operations at various depths both within the river bed and on-shore. The results, together with Vibrock data from previous surveys of a similar nature, formed the basis of the study that ensured that the Shad continues to spawn in the area undisturbed.