Aggregate dredging puts windfarm at risk
Dredging of the sea bed off the East coast of England to provide aggregate material for construction use has long been of concern to locals and environmentalists. Marine Ecological Surveys recently carried out have found that the sea bed has dropped by between three and five metres at the dredging sites off Great Yarmouth. Now new evidence shows that the resulting erosion area is widening.
A serious threat to the windfarm offshore from Great Yarmouth has been discovered. Previously many of the turbines had been found to be base mooring destabilised. These had been fortified by placing rock bunds around them to stop further erosion. The company involved are now employing experts to carry out a survey of the whole seabed around the windfarm area.
Preliminary investigations around the bases of the turbines show that the mooring bases, set sixty feet down into the sea bed are now only forty-five below the surface of the seabed, and that the windfarm to shore power cable, originally set in a deep trench with concrete cover, is now eleven feet above the seabed.
Fortunately in the immediate areas at the base of the structures, the emplaced rock bunding appears to have retained the sand and shingle, so the loss of the entire system is not imminent.
Evidence is widespread that offshore dredging for building industry aggregate can cause coastal erosion, by draw down of beaches, by intensifying wave action, by altering tidal patterns and by removing sand banks which have previously protected coasts.
This activity and the subsequent ecological repercussions are particularly worrying in the light of the government’s announcement re the construction of a new generation of nuclear power stations, one of which is projected to built alongside the existing station at Sizewell in Suffolk.
Not only do the power stations themselves require vast amounts of aggregate to be used onsite, but there is also a safety issue because of the coastal positioning of the facility. While Sizewell beach is said to be stable at present, local dredging may cause serious destabilisation of the beach during the time span of Sizewell B, let alone that of any new nuclear stations on the Suffolk coast.
Campaigners say that environmental impact assessments made before licences are granted, and after dredging has been carried, out are inadequate to reveal damage to the seabed and increased likelihood of coastal erosion.
