Offshore Marine Management (‘OMM’) has successfully completed a contract for Prysmian Powerlink as preparations continue for the installation of BorWin2, which will connect new wind parks off the coast of Germany.
Using the 2,000 tonne multipurpose vessel Bourbon Enterprise, OMM cleared the route proposed for the 124km (77 miles) high-voltage direct current export cable that will connect the new wind parks to the onshore grid. This involved identifying out of service cables along the route, and then using a grapnel and chains set up to bring these cables onto the vessel, for later safe disposal on shore.
OMM then conducted mattressing of the existing in-service underwater assets, including telecommunication and electricity cables as well as gas pipelines. Using a remotely operated underwater vehicle launched from the vessel, OMM’s team conducted a detailed survey of the sea bed, before identifying the correct position for each mattress and then releasing each into its location. A post-installation survey confirmed that no interference with third party assets had taken place.
Finally, OMM used the Bourbon Enterprise to conduct a Pre Lay Grapnel Run (PLGR) to clear the seabed of debris and other unwanted materials such as fishing lines – to ensure the route for the new Prysmian cable was clear and in good condition for cable installation.
Commenting on the project, OMM’s Project Manager Michael Finnerty , said: “ The wind parks that will be connected via BorWin2 will be some of the largest yet built off the German coast, generating in the region of 800 megawatts of clean electricity. Our client demanded comprehensive route clearance and PLGR support from us – as well as mattressing along both the HVDC and separate AC routes that will run between two new offshore substations.
“OMM has a strong working knowledge of Prysmian’s projects in the North Sea and our ability to conduct such crucial pre-installation work efficiently and thoroughly demonstrates we are an ideal business partner for this type of project.”
OMM’s work on BorWin2 follows similar work the company successfully completed on Germany’s first HVDC link, BorWin1.
In November 2011, OMM announced it had completed its first cable storage task for Prysmian and Siemens Energy.
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Offshore WIND staff, May 31, 2012; Image: TenneT