Offshore Wind Accelerator: CPT-based assessments for subsea cables

Offshore wind (OSW) developers have commercial pressures to delay DEVEX (development expenditure) on Geotechnical Site Investigation (SI) while securing cable supply and installation earlier due to supply chain constraints. This reduces the window to provide Geotechnical SI factual data and interpretation for cable design and installation assessments. Further, export cable routes are getting longer meaning more time and cost required for SI than before. Crucially, while demand for offshore wind is expected to increase for the rest of the decade, capacity in the SI supply chain is not.

For all the reasons above, there is a high risk that within the next couple of years, it may not always be possible for OSW developers to secure geotechnical SI data in time for cable tenders. This will put the execution of OSW projects at risk of significant delay and/or higher DEVEX (e.g. performing Geotechnical SI in winter conditions, unknown ground conditions for Offshore Cable Installation (OCI) Contractors etc).

Switching from the use of SI data sourced from geotechnical laboratories to CPT/in-situ techniques for cable assessments has been identified as a potential solution to resolve these challenges.

The OWA TWG-Cables would like to identify and validate a CPT/in-situ based site characterisation method that is fit for purpose for cable design and installation assessments to limit the need to perform geotechnical laboratory testing, to support cable installation tenders.

Key experience