Wednesday 8th of May 2013
The transformer station for the offshore wind farm Global Tech 1 was successfully installed
The wind farm’s internal transformer station was delivered complete for use by the consortium Alstom Grid GmbH and Keppel Verolme B. V. The steel structure of the platform was constructed in Rotterdam by Keppel Verolme and the electrical equipment installed by Alstom Grid directly at the Dutch shipyard. Two seagoing tugboats took three days to tow the floating, closed steel body of the transformer station from Rotterdam to the construction zone. In total four tugboats were needed for positioning.
The legs of the support structure, which were affixed to the body and towered above it during the voyage, were then descended to the seabed. The suction caissons are mounted as the four feet of the supporting legs. With each a height of 9.5 metres and a diameter of 11 metres these steel cylinders were first pressed into the seabed under the weight of the platform itself, 9,000 metric tonnes.
In the next step, pumps drew out the seawater in the cylinders, thereby producing a negative pressure that pulled the suction caissons into the seabed. In a third step, the station was jacked up 20 metres above the sea surface and locked into place.
Cathie Associates, acting as both geotechnical consultant for the suction caissons for GT1, and as geotechnical designer on behalf of SPT Offshore for Keppel Verolme, is pleased to be associated with this project. The installation was achieved within pre-determined design limits. This once more proves suction caissons to be an environmentally-friendly (noiseless) and suitable foundation means for offshore structures in the offshore wind industry.