When Marinus Link was first announced by TasNetworks, Tasmania’s electricity transmission and distribution company, they had limited experience with marine operations or execution know-how. This is to be expected for an organisation that has only managed land-based assets, on an island where the last major offshore project was the existing interconnector, installed almost 20 years ago.
CoreMarine was brought in to provide advisory services around offshore contracts, execution methodologies and areas of opportunity, and to ensure offshore campaigns were run safely and efficiently. Marinus Link is one of Australia’s most significant energy projects, and CoreMarine was stoked to bring its international expertise to critical early-phase work.
Working with both the broader Marinus Link team and other external consultants ensured TasNetworks was armed with the information it needed to set up Marinus Link for success. The data captured in these offshore campaigns helped to understand the seabed, identify optimal routes, and allow for cable design tailored to the exact offshore conditions. This significantly de-risks the project as it approaches final investment decision (FID).
What is Marinus Link
Marinus Link is “a proposed undersea and underground electricity and telecommunications interconnector between North West Tasmania and the Latrobe Valley in Victoria. The project comprises high voltage direct current (HVDC) cables, fibre optic cables, and converter stations in both Tasmania and Victoria.”
It will be one of the longest, most complex energy interconnectors ever built, at 345 km long – 255 km of which will be subsea – comprising two 750 MW links.
Our role
We have provided two main roles for the project:
- Offshore campaign management, and
- Technical advisory.
In our offshore campaign management support, we covered all the marine operations conducted by the project.
As part of the project’s site selection and optimisation phases, CoreMarine supported in the specification and execution of the two main geophysical and geotechnical campaigns in 2019 and 2022. As the client site representative for both marine campaigns, our role covered:
- Scope development and technical procurement support,
- Marine spread specification,
- Bidder review and clarifications,
- Contractor follow-up for the delivery of the marine and geo spread, and
- Daily management of the campaign to ensure the safety, efficiency and quality of work.
The initial reconnaissance campaign covered:
- Detailed geophys of the whole route,
- Assessment of multiple shore crossing options,
- Sidescan, multibeam and ultra-high resolution seismic works, and
- Geotech sampling along the proposed route to “ground truth” the geophys data collected, including grab samples and vibrocores.
The Marine Engineering GeoTechnical Site Investigation (MEGSI) campaign was conducted after final route selection. It was one of the most comprehensive transects of Bass Strait done to date, involving:
- Sampling over 150 locations along the route, including vibrocore, pistoncore and cone penetration testing (CPT),
- Shallow water samples that obtained geotechnical data at the horizonal directional drilling (HDD) alignment for both ends of the cable,
- Additional scope to look at potential cultural heritage locations identified during the reconnaissance geophys campaign, and collecting multiple seabed samples for use in archaeological research.
CoreMarine also supported the project in the nearshore geotech campaign for the Tasmanian end HDD alignment. This work included the use of a small jack up barge operating close to shore.
In our technical advisory role, we provided support across several areas.
We carried out the technical management of the contractor developing the project’s metocean and seabed mobility report. This included:
- Development of a dedicated Bass Strait metocean model,
- Review and approval of results,
- Review and guidance on the nearshore seabed and coastline morphology,
We have also provided ad hoc advisory to the Marinus Link project, including:
- Marine contracting principals,
- Marine operations execution strategy,
- Weather risk planning for cable lay operations, and
- Local advisory for execution of marine operations.