LDD, in collaboration with its sister companies from Acteon Group, UTEC and MENCK, has delivered a subsea Pre-Piling Template (PPT) to Offshore WindForce (OWF), which is installing 70 foundations at the Wikinger offshore wind farm.
LDD’s PPT is being used by OWF, a joint venture between Boskalis and Volker Stevin International, to pre-install foundation piles into the seabed, before Boskalis vessel Giant 7 starts with placing and grouting the four-legged jacket foundation structures.
LDD has produced the detailed design of the template structure, which has been manufactured by Volker Staal en Funderingen B.V. in Rotterdam, the Netherlands. LDD was responsible for the design, supply, installation and commissioning of the hydraulic, survey and control systems onto the PPT. The survey system was designed and supplied to LDD by UTEC.
A computer-controlled subsea hydraulic system automatically levels the PPT on the seabed and allows operators to adjust pile position and verticality to within the required +/-50 mm and 0.5 degree installation tolerances. The metrology system installed on the PPT includes real-time survey data on the PPT position and orientation, plus pile location, verticality and depth monitoring.
Rob van Gemert, Project Director, Offshore WindForce, said: “The PPT and its components are well on track and they will be tested to the extreme on the Wikinger project.”
OWF has also contracted MENCK to provide a service package including the supply of two MHU1200S hydraulic hammers to drive the jacket piles to depth.
In order to achieve the German noise emissions standards and connecting with the commitments of the parties with environmental issues, both OWF, LDD and MENCK worked together to develop noise mitigation solutions to incorporate into the PPT and hammer deployment systems.
The PPT is fitted with a ‘Small Bubble Curtain’ system that can be activated at each pile guide sleeve, whilst the piling hammer and pile are deployed within a HydroSound Damper (HSD) system. An OWF deployed ‘Double Big Bubble Curtain’ surrounds the entire template, providing three means of mitigating the effects of noise during piling operations.
The installation of the first foundations at the Wikinger offshore wind site started at the end of April, and further jackets have been recently prepared to leave Bladt Industries’ Lindø Facility in Denmark.