Van Hattum en Blankevoort has started work on extending the deep-sea quay wall of Sif, commissioned by the Port of Rotterdam Authority. This is the second part of the deep-draught quay of the port. The quay wall in the Prinses Arianehaven in Rotterdam Maasvlakte is to be extended by 200 metres with a retaining height of 30 metres.Sif Netherlands BV manufactures large steel pipes that are used for the foundations of offshore wind turbines. At the Sif quay in Maasvlakte, these 120-metre-long monopiles, 11 metres in diameter, are loaded onto gigantic offshore installation vessels. Once offshore, the monopiles are driven into the sea bed as a foundation for the wind turbines.The Sif quay is specifically designed for receiving so-called jack-up vessels, which place their legs on the port bed and are then jacked up for taking the foundations or other wind turbine parts on board.This quay wall extension gives Sif the possibility of adding storage, installation and marshalling of turbines, blades and pylons for offshore wind farm to its services for the offshore wind industry. The first customer to make use of the quay will be Siemens Gamesa for the Hollandse Kust (South) project. Sif will supply all turbine and foundation components for the wind farm from the Sif terminal.Realising a part of the quay with the deepest draught in the port of Rotterdam is a complex matter. When complete, the quay will rise about thirty metres from the sea bed and will have to withstand the load of monopiles on the quay and offshore working vessels berthed alongside. To ensure the quay height can be extended even further, it has been built an extra metre deeper than required when the quay is commissioned.