UK: LDD to Begin Work on Gwynt y Môr Wind Farm

LDD, an Acteon company providing near and offshore drilling and foundation services, announced that its custom-built LD5000 pile top reverse circulation drilling rig has been delivered to Birkenhead, UK, where LDD will use it to provide critical pile relief drilling for the installation of up to 160 wind turbine foundations.

The wind turbines will form part of the Gwynt y Môr wind farm project located 11km off the North Wales coast in Liverpool Bay.

“The Gwynt y Môr project is extremely exciting for us, as one of the largest wind farms currently in construction in Europe. Developing the LD5000 really put our engineering expertise and creative abilities to the test,” said Andy Seager, Vice President – Operations for LDD.

Production of the LD5000 showcases LDD’s equipment design and production capability. The drilling equipment spread, which weighs around 400 tonnes in all, of which the drilling rig measures over 17 metres in height, was designed and delivered in 10 months from contract award and is capable of drilling up to 8m in diameter.

To handle the large-scale components involved, it is extraordinarily powerful and has the ability to produce 1100kNm of continuous torque and 500 tonnes of pull-back.

The LD5000 is equipped with programme logic control (PLC), which makes it possible to control it either electronically or via a manual back-up system, with great ease and ultimate control.

Safety in design in accordance with the UK Construction Design and Management regulations 2007 (CDM) was a key consideration for LDD’s engineering team. By incorporating the most up-to-date safety features, LDD believes it has developed one of the safest pile top drilling rigs currently on the market. LDD’s efforts to address safety during the site mobilisation of their equipment were awarded a green card and safety award from RWE for ‘safe pro-active working exceeding the requirements of Method Statements and Risk Assessments’.

Offshore construction activity for Gwynt y Môr has begun in Liverpool Bay with preparations to the seabed, known as scour protection.

LDD’s capabilities are now turning to the development of a seabed piling template for the pre-installation of jacket piles, piling gates and a range of lifting and handling tools.

 LD5000 facilitates installation of large tapered monopiles

Most of the wind turbine foundation monopiles are expected be driven to target depth with a hydraulic hammer. However, when hard geology is encountered that prevents the monopile from reaching its installation depth, the LD5000 will be transferred from the installation vessel,to replace the hammer and drill out material inside the monopile and beyond. Once the relief drilling has been completed, the hammer will replace the LD5000 and the drive-drill-drive sequence will be completed by driving the monopile to its target depth.

Because the wind turbine monopiles are tapered – 4.6 m diameter at the top and between 4.7m and 6.0m at the bottom – they pose unique challenges for the pile relief drilling. LDD designed the LD5000 with an under-reaming drill bit, so that it can pass through the neck of the monopole and drill a range of rock socket diameters, from a standard 4.6m diameter up to 6.0m.

The LD5000 makes it possible to fine-tune the diameter and depth of the rock socket in direct correlation with the exact diameter of the monopile. This means that installation of the monopile will be fully optimised. It also ensures that when the monopile is eventually driven to target depth, the external wall of the monopile will be in direct contact with the surrounding bedrock, providing the wind turbine generator with long-term stability.

Along with LDD, sister company MENCK is providing an MHU 1900S submersible hydraulic hammer to install all 160 foundations.

LDD will provide pile relief drilling services for two years throughout the construction of Gwynt y Môr. The range of services provided by LDD supports the Acteon Group’s commitment to linking subsea services across a range of interconnected disciplines. LDD is a member of Acteon’s Foundations and Moorings operating group.

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Offshore Wind Staff , April 02, 2012; Image: LDD