HYDRO SOILS Services has finished building the Utgrunden offshore wind farm park in the Baltic Sea off the south east coast of Sweden.
Working for client Enron Wind Sweden, the Belgian marine contractor, a joint venture of Smet Boring and Dredging International, transported and installed seven 1.5MW units.
Each 65m high windmill is made up of a monopile foundation, a tower, a nacelle (a streamlined engine housing) and a 70.5m diameter rotor.
The 36m long, 3m diameter monopiles were transported by barge from Denmark to the site,12km off the coast. Each 140t pile was lifted into position by a jack-up platform and driven 19m into the seabed.
The pile caps were fitted with a transition piece - a working platform and a cantilevered transformer bed - 5m above sea level, using a specially designed grouted sleeve connection. A smaller jack-up collected the towers, nacelles and rotors from Bergkvara in Sweden. Both jack-ups were then used in tandem to lift the modules in position.