Longitude, part of LOC Group, has completed a range of environmental engineering analyses, crucial to supporting the planning for upcoming export cable installation operations for the St Nazaire offshore wind farm, in France.

Under the agreement, provided by Prysmian Group, the scope of work included analysis of vessel grounding and mooring in nearshore locations, landfall cable pull-in analysis, to ensure cable integrity, export cable free lay from the nearshore to the offshore wind farm, survival analysis for vessel operations in bad weather and seabed evaluation to ensure the cable remains stable prior to being buried.

Longitude’s work in metocean engineering provided an understanding of tide, current and waves at the shore approach location, including generating 3D hydrodynamic modelling. This was critical to Prysmian’s ability to plan operations, given strong and changing tidal currents, due to the location of the wind farm, close to a river estuary.

The wider LOC Renewables team has also contributed at other stages of the St Nazaire OWF project under other contracts, including a geotechnical analysis of leg penetration and soil stiffness.

“Delivering the scope of work under this agreement demonstrates the breadth of services we can offer across a project’s lifecycle, and the value our multidisciplinary approach adds to clients’ projects. An example of this is the provision of cable stability analysis and work on the landfall cable pull-in. In-depth stability analysis requires consideration of a range of potentially contributing factors. To understand these factors you need a specialised combination of environmental engineering expertise, providing an analysis of the soil properties from a geoscience perspective, and tidal, current and weather conditions for the location from the metocean perspective.”

Andrew Butler, managing director of Longitude.

The St Nazaire offshore wind farm is located in the Loire-Atlantique region of France. It is owned by Eolien Maritime France (EMF), a joint venture formed in May 2016 between EDF Renewables (50%) and its subsidiary Enbridge (50%).

Once operational in 2022, the €2 billion project will supply approximately 20% of the domestic electricity consumption of the Loire-Atlantique region.