Marine survey services

Description

The ‘Biscay Gulf Electrical Interconnection FR-ES’ is a joint project developed by INELFE on behalf of Réseau Transport d’Electricité (RTE) and Red Eléctica de España (REE), respectively the transmission system operators in France and Spain. The project is supported by the European Union’s Connecting Europe facility (CEF). The Biscay Gulf electrical Interconnection consists of the construction of a 2 000 MW link. This link is composed of 2 (two) circuits rated 1 000 MW each for DC operating voltage of 400 kV, comprised of 4 power cables, 4 converter station terminals located close to 400 kV Cubnezais substation (France) and Gatica substation (Spain). The length of the route is estimated to be approximately 400 km long starting in Spanish Pais Vasco region (near Bilbao) to an ending point in Nouvelle Aquitaine (Gironde department, near Bordeaux). The interconnection is composed of underground cables with total approximate route length of 100 km and submarine cables with total approximate. The services consist of integrated survey: geophysical and geotechnical to be performed in the Biscay Gulf in water depths ranging between 0 and approximately 80 m LAT in Spanish waters. The purposes of the geophysical and geotechnical investigations are the determination of the detailed seabed conditions and stratigraphy with detailed characterisation of the materials in the surface and subsurface soil layers in order to inform the installation of submarine cables. UXO survey could potentially be required as well. The geophysical investigation shall include both surface and subsurface survey (subbottom profiling). The purpose of the UXO survey is to ensure an As Low As Reasonably Practicable (ALARP) UXO risk at each anticipated geotechnical location to be investigated during the subsequent geotechnical survey. The execution of the UXO survey will be subjected to the risk mitigation strategy adopted. The geotechnical investigation shall consist in CPTs, vibro cores, rock cores and similar. It includes the collections of quality samples of soil and rock to be tested onshore and offshore for the determination of physical and mechanical properties, to support the interpretation of the geophysical data.