The construction of a liquefied natural gas (LNG) plant on the Yamal Peninsula called Yamal LNG began in 2012. The project requires the construction of transport infrastructure including a new, strategic Arctic sea port, north-east of the Yamal Peninsula.
A jetty with two LNG tanker loading berths at the port of Sabetta, equipped with ice protection facilities, is being built during the main marine construction stage.
And to be operational, dredging works are required in the New Sabetta Sea Port Area at Berths #5-6, as well an extension of Berth #1.
Cold and long winters with low snow cover cause profound and lasting soil freezing in this area, which leads to the formation of permafrost. Thickness of permafrost soils near the Polar Circle varies in the range of 400-450 to 250-300 m. Special dredging equipment is selected due to shallow water depths and presence of this type of soil (permafrost). Thanks to modern technology and high installed power this equipment is able to dredge very hard materials, including rock and permafrost.
Due to the geographical situation, dredging works need to be executed within a limited period of only 10 weeks between July and October, when access to the work area and the area itself is ice-free. Therefore, the dredging operations were executed within a period of approximately 65 days during the 2015 ice-free period.
On top of these challenges a part of the works are performed offshore including accommodation of all the crew and staff deployed on site. The project has to be totally self-sufficient without the need for coastline support.
The total dredging scope during the navigational season of 2015 is approximately 1.6 mln cbm, mostly permafrost.
For Sabetta Port this comprises:
o Berth #1 extension: 0.4 mln cbm
o Berths #5-6: 1.2 mln cbm
Complexity of the project is enhanced by a continuous interface of third parties on and near the site (including but not limited to construction of the quaywalls). Thus close liaison and cooperation with the quaywall contractor, thorough coordination and operational flexibility are required not to hinder or delay the works.
For this complex project with interference of third parties/ another project ongoing/ large number of equipment deployed and time restrictions due to a short ice free period, an impressive variety of dredgers from the DEME fleet are involved. These include one of the most powerful Cutter Suction Dredgers in the world, barges for offshore dumping, a Trailing Suction Hopper Dredger, 2 excavators installed on pontoon and supporting/auxiliary fleet for Sabetta Port.