This is how we build caissons for the deepwater breakwater of the FSRU terminal
The construction of the deepwater protective breakwater for the FSRU (Floating Storage Regasification Unit) terminal in the Gulf of Gdańsk is gathering pace. Precast caissons, which are large-scale reinforced concrete boxes, will form a structure approximately 1.3 km long. This will ensure the safe operation of the FSRU terminal and protect the regasification unit from wave action. To date, 13 out of the 24 planned caissons have been fabricated, and the first two have already been installed in their target locations.
The investment project by the Maritime Office in Gdynia, delivered by NDI, encompasses not only the construction of the protective breakwater for the FSRU berth along with soil replacement, but also the installation of navigational aids related to this infrastructure, as well as dredging and clearance works on the approach channel and the turning basin for the FSRU terminal.
Currently, one of the most critical stages in the delivery of the breakwater is the production of the precast caissons. This takes place in the Inner Basin of the Port of Gdańsk using slipform shuttering technology. Due to the specific nature of this technology, the works are carried out uninterruptedly, 24 hours a day, which requires precise cooperation among numerous construction teams and the seamless coordination of all delivery phases.
Each precast caisson is over 55 metres long, 15.5 metres wide and nearly 15 metres high. Its execution requires approximately 1,758 m3 of concrete and around 267 tonnes of reinforcing steel. The technology applied allows the entire process – from executing the concrete structure of the box and installing its reinforcement up to the launching – to be delivered within just 11 days. Thanks to this technique, during approximately 85 hours of continuous pouring, the caisson walls are formed as a single, seamless element without any construction joints, which translates into greater structural durability.
The scale of the venture is best illustrated by the fact that a reinforced concrete structure the size of a four-storey residential building is created in less than two weeks. Subsequently, the caisson is launched, towed to a temporary storage or installation site, and precisely positioned on the seabed with centimetre-level accuracy.
The FSRU terminal, along with the construction of the protective breakwater, is a critical investment project for Poland’s energy security, ensuring the diversification of gas supply sources and routes.
