Environmental dredging and deepening Aibel

About the project

The project was part of the preparations for Johan Sverdrup P2 and included both dredging and blasting under challenging conditions. The assignment involved dredging around 14,000 tonnes of contaminated loose materials and blasting approximately 3,000 m3 of rock. Due to the high level of contamination, all materials were transported by ship to NOAH Langøya for proper disposal. To prevent particle dispersion, silt curtains, bubble curtains, and turbidity meters were used throughout the project.

Blasting took place right next to the dock wall, while the dock was in use for repairs on Njord Bravo, which imposed strict vibration limits of max 27 mm/s. Four vibration meters were installed at the construction site, and precise seam drilling just 2.5 metres from the dock wall was necessary. The dry dock was operational throughout the project, which imposed additional demands on planning and safety. The use and maintenance of the silt curtain in Karmsundet was challenging due to strong currents, and when receiving ships from NOAH, the bubble curtain was used when opening the silt curtain.

Part of the assignment also included detaching and disposing of four heavily reinforced concrete crosses, former foundations for platform rigs. These were crushed by blasting, and all vibration requirements were met. Throughout the project, weekly meetings were held with Aibel and the project organisation for the Njord B project, as well as close dialogue with Kvitsøy VTF regarding boat traffic and the use of the silt curtain.