Dieppe Le Tréport Offshore Wind Farm – Post-Lay Burial & Protection Works of Export Cables

The Dieppe Le Tréport OWF Export Cable Project involved the protection and burial of two 245 kV XLPE submarine export cables connecting the offshore wind farm to the French electricity grid operated by RTE. The project site is located in the English Channel, approximately 17km off the coast of Penly, Normandy, France. 

Asso.subsea’s scope of work, contracted by Nexans, included the mechanical trenching and post-lay burial of a total of 7.2 km of export cables, an extended scope following successful initial operations on the planned 4.8 km section. Operations were performed using the AssoTrencher IV Mk13, supported by the Athena vessel. 

Key project challenges included: 

• Unpredictable seabed conditions in shallow waters, with variable combinations of sand, gravel, and weathered chalk 

• Dynamic tidal ranges impacting operations and requiring a carefully engineered tidal execution plan 

• The need to manage equipment sinkage risks and ensure cable integrity during burial operations 

In addition to post-lay burial, Asso.subsea deployed specialized positioning and monitoring systems (such as GAPS) adapted for shallow water conditions, while trenching performance was optimized through effective trafficability tests and real-time seabed data assessment. 

Scope of Work Summary: 
• Mobilization and pre-execution planning 
• Mechanical trenching (Post-Lay Burial) with AT IV Mk13 
• Installation of shallow-water positioning systems (GAPS) 
• Trafficability tests and risk management 
• As-buried surveys (MBES)