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Testing a new asset in difficult seabed as well as difficult economic conditions

Wednesday 24th June 2020

Initial trials and testing of any brand new, large-scale asset naturally comes with challenges and often unexpected curve balls, but add a global pandemic into the mix and you have a truly unique set of circumstances and ‘firsts’ to tackle. Our 115 tonne Pre-Lay Plough, the PLP240, is a new design of plough giving an unrivalled capability to simultaneously prepare, trench and protect cable routes in the most difficult of seabed conditions across multiple markets, including offshore renewables as well as oil & gas. 

Liam McNeil, one of our Project Engineers involved in the PLP240 project right through from the design stage, has been telling us a bit more about how the project has been managed during such strange times.

Was the initial mobilisation of the PLP240 impacted by the start of the Covid-19 pandemic?

Our initial mobilisation of the PLP240 commenced late February, when the Covid-19 situation in the UK was not fully realised, and was complete within the first week of March. It was as we performed the initial stages of the trials that the seriousness of the situation globally became apparent.

Can you tell us a bit more about the types of testing we put the PLP240 through?

The trials were designed to assess the PLP in all modes of operation against the design criteria: Boulder Clearance, Pre-Cut, Simultaneous Boulder Clearing and Pre-Cut, Multi-Pass and Backfill. It was not only the PLP that was trialled but the entire supporting spread of survey and ROV equipment and the vessel, the modern and fuel-efficient Havila Jupiter.

In order to ensure that the trials were representative of the whole site conditions within the Danish Kriegers Flak area, which our client Vattenfall is developing, routes were carefully selected for their seabed types (granular, cohesive, clay till and surface boulder density) where comprehensive geotechnical/physical Site Investigations had taken place. This allows for an accurate comparison of the performance and prediction models with the real-life values and gives added confidence to the analysis of the results as the seabed conditions are known.

The trials were wholly successful, with the PLP and spread able to demonstrate the ability to clear the route of boulders and cut a trench to depth, in an accurate, stable and repeatable manner and, crucially, safely.

Video: Global Marine Group’s PLP240 – initial load out onto the Havila Jupiter in Blyth ahead of initial trials and Global Offshore’s Danish Kriegers Flak project with Vattenfall

Were operations offshore impacted by the current Covid-19 climate?

Offshore, with the personnel on board effectively in isolation from the outside world while at sea, we were aware that our major risks arose from port calls and crew changes. Our normally high levels of cleanliness on board and hand hygiene were increased, with the catering staff ensuring that handrails were disinfected daily. An update on Covid-19 was added to the daily meeting of the Supervisory Team and guidelines provided by the company as well as national advice were made available to all personnel on board.

We also took steps to ensure that everyone’s health and wellbeing was being looked after, ensuring that good communications with home was available to all, and also embarking a medic with supplies of PPE and Covid-19 testing kits.

Despite logistical challenges with very limited flights and accommodation availability, we managed to continue to perform scheduled crew changes safely, by isolating all onsigners in country for seven days prior to embarking the vessel.

How have you worked with suppliers and customers to manage these impacts?

As the vessel was working in Danish waters, we were heavily dependent on the our local agents to assist us with developing a network of local suppliers for goods and services but also to communicate the local/national regulations and restrictions in place due to Covid-19. This worked both ways as it allowed us to communicate to our suppliers through the agents what restrictions we had imposed on the vessel in order to protect the health and security of the crew on board.

One such example was performing steel fabrication works during a port call. All communications with the shoreside fabricators had to be via phone or email, so ensuring clear and concise engineering drawings were in place was key. We also had an additional resource flown in from the UK to manage and communicate back to the vessel the progress of the off-site works so we could monitor and adjust our plans. For works aboard the vessel, workpacks and radios were left at the worksite, with clear instructions that no third party personnel were to enter the vessel accommodation. This worked very well and the works were completed on time and in specification. 

With the support of our client Vattenfall, we performed an on-site emergency response drill, simulating a confirmed case of Covid-19 on board. All parties on and offshore, including the Danish Authorities well were co-ordinated, demonstrated professionalism, and confidently carrying out their roles giving comfort that clear plans were in place should this happen in an non-simulated situation.

The asset’s first project has been on Vattenfall’s Danish Kriegers Flak Wind Farm – did the plough perform as expected?

The PLP240 has completed 158km of route clearance on the site in total, over 72 different routes. Despite the tough conditions, the PLP240 has achieved target trench depths in over 99% of the routes, going over and above the project requirements and almost wholly de-risking the cable burial, with a target share depth of 1.7m across all routes. Performance exceeded the expected levels of efficiency, meaning that where two passes were predicted to be required to attain depth, only one was required in most areas. This has been a key deliverable for us in 2020, and it’s already proved to be the right investment for us as a business, delivering exactly that we promised that it would for our customers.

What’s next for the PLP240?

Having wrapped up on the Vattenfall site, the Havila Jupiter and PLP240 will next be sailing to the Kincardine Floating Offshore Wind Farm working for Grupo Cobra to begin route preparation and boulder clearance operations there.

Above: The the key principles of the PLP240 are that all surface boulders are cleared right to the outer edge, separate from the trench spoil and we have an accurate, well defined trench to a good depth lay the product in.