How can offshore installations protect their turbine footings from ocean scour?
The Amrumbank West offshore wind farm is located 35 km north of Helgoland, Germany and 37 km west of the North Frisian Island of Amrum. It extends over 34 km² and has 80 Siemens 3.6 MW class wind turbines and a generating capacity of 288 megawatts. How can offshore installations like this protect their turbine footings from ocean scour? Nonwoven geotextile containers replace the typically several meter thick bedding layer of expensive large stones or rocks.
For monopole offshore installations, Secutex® Soft Rock sand containers have been used, including GPS support for precise seabed placement. The containers are fabricated from a Secutex® highly robust, staple fibre, needle-punched nonwoven geotextile. Containers are sewn together and closed after sand filling with a high-performance durable yarn. After sand filling, the container remains flexible and can adapt to variable seabeds. Secutex® Soft Rock offers outstanding long-term stability, a high contact angle of friction, high permeability, and high abrasion resistance.
This geosynthetic solution enables the use of on-site fill, which provides considerable savings on material acquisition and transportation. It also shortens the construction window. Additionally, the nonwoven geotextile sand containers allow a decoupled construction process, because they can be installed before ramming of the monopile and unlike the rock bed they do not damage the coating of the monopiles when driven through the protection layer deep into the seabed. This construction solution protects the turbine footings and other offshore structures against seabed washout and erosion around the structure.
Offshore advantages with Naue
Offshore installations such as port walls, monopiles for wind turbines, and groynes can be subjected to significant and erosive wave forces. Geotextile-based systems can provide the filter stability and abrasion resistance for true scour protection of these installations. This ensures that offshore structures provide the service lives for which they are designed.
Naue Secutex® H provides exceptional durability for longterm scour protection. Filter stability is provided by the durability-enhancing strength of the needle-punch manufacturing process for Naue’s nonwoven geotextiles. The selection of Secutex® H geotextiles for offshore installations also provides significant ecological advantages by way of greater reuse of site soils, decreased transportation costs for material delivery to site, and simpler, faster, more affordable constructions that last longer.