Using the 2000 tonne multipurpose vessel Bourbon Enterprise, OMM successfully completed the contract for Prysmian Powerlink and cleared the route proposed for the 124km (77 miles) cable that will connect the new offshore 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 explained.
The firm 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, a Pre Lay Grapnel Run (PLGR) was conducted to clear the seabed of debris.
“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,” said OMM’s Project Manager Michael Finnerty. “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.”