GAZ-SYSTEM has completed one of the most technologically demanding stages of construction of the marine section of the FSRU terminal – the drilling of a more than one-kilometre-long microtunnel for the subsea gas pipeline. The work was completed almost one month ahead of the baseline schedule and without any major technical difficulties.

The TBM machine drilled a 1,100-metre-long tunnel off the coast of the Gulf of Gdańsk, passing without major obstacles through the ground beneath the coastal zone, including the forest, dunes and beach at Górki Zachodnie. The completion of all works related to the construction of the microtunnel is scheduled for autumn 2026. The final stage of this part of the project will be the recovery of the machine to the surface and the sealing of the tunnel exit with a special bulkhead.

“The FSRU terminal in the Gulf of Gdańsk will increase Poland’s access to the global LNG market while strengthening the national transmission system. This is important not only for diversifying supplies, but above all for our ability to manage gas security flexibly in changing market conditions. We are developing infrastructure that will enable Poland’s coastline to realise its potential as an important entry point for gas into Central and Eastern Europe. The drilling of a 1,100-metre microtunnel beneath the coastal zone, beach and seabed of the Gulf of Gdańsk demonstrates the technical scale of this investment and the precision of the work being carried out. It is another step towards commissioning the terminal in 2028” – said Energy Minister Miłosz Motyka.

“With each successive stage, we are moving closer to commissioning a terminal that will increase LNG import capacity for Poland and the region. Completing the microtunnel ahead of schedule is a shared success for our project team and the Polish construction company. Thanks to professional coordination of the investment process, we are effectively combining specialist expertise and technology with care for the surrounding environment, while maintaining the project schedule” – said Sławomir Hinc, CEO of GAZ-SYSTEM.

More than one kilometre of tunnel without disturbing the beach or dunes

The microtunnel was constructed using a trenchless method with a Herrenknecht AVND 2000 AB microtunnelling machine. This technology allowed the route to be constructed beneath the surface without the need for an open excavation. The approximately 2.5-metre-diameter tunnel was reinforced with 376 prefabricated reinforced-concrete pipes which, together with the sealing system, form its load-bearing structure. A total of 5,744 cubic metres of excavated material was removed during the works.

Thanks to the use of trenchless technology, the beach and coastal areas at Górki Zachodnie remained virtually undisturbed, allowing residents and tourists to continue using them throughout the construction works. The precise execution of the microtunnelling works also made it possible to maintain the planned crossing route. This avoided design changes during construction and enabled the pipeline to be installed efficiently in accordance with the project’s technical requirements and schedule.

Microtunnel prepared for the subsea gas pipeline

The tunnel is not an independent part of the transmission infrastructure. Its purpose is to provide a secure corridor for the installation of the subsea gas pipeline and associated infrastructure connecting the FSRU terminal with the onshore transmission system. The microtunnel will protect the pipeline along the section running beneath the land and seabed of the Gulf of Gdańsk in the coastal zone. It will also enable the installation of fibre-optic cables and other associated infrastructure along the pipeline.

“Basia” – a machine designed to operate in challenging conditions

The Herrenknecht AVND 2000 AB is a 12.5-metre-long machine consisting of four sections. The heaviest component, fitted with the cutting wheel, weighs 42 tonnes. For the purposes of the project, the machine was additionally equipped with a sea-recovery system enabling its safe retrieval from the seabed of the Gulf of Gdańsk once drilling is complete. Disconnecting the machine from the microtunnel will require complex diving operations, followed by its recovery using floating cranes.

Next stages of construction of the FSRU’s marine infrastructure

Installing the gas pipeline inside the drilled tunnel will require further stabilisation of the tunnel within the surrounding ground, temporary sealing of the seaward end, installation of associated systems and preparation of the TBM machine for recovery to the surface. The microtunnel will also be fitted with components designed to ensure the safety of the pipeline installed inside it and to stabilise the trajectory during pipeline installation.

All elements of the marine section of the project are scheduled to be completed next year, while the FSRU itself is expected to be moored in the waters of the Gulf of Gdańsk towards the end of 2027.

About the FSRU terminal