ZUG, Switzerland -- The Nord Stream consortium has contracted the Dutch joint venture Boskalis-Tideway Offshore for post-lay rock placement. Work on the $133-million contract is due to start in 2011 and should be completed in 2012.
Various pipelay contractors are installing the Nord Stream trunklines, which will take gas from fields in northern Russia through the Baltic Sea to mainland Germany.
Pre-lay rock placement is currently being performed in certain sections of the pipeline route to create a stable base for the pipeline and to keep resultant free-spans to acceptable lengths.
In some areas, rock berms will also be installed post-laying to protect the pipelines against fatigue.
Rock for this activity will be sourced from countries on the Baltic Sea coast. The rock material has to be free from clay, silt, chalk, vegetation, or other damaging substances in order to meet the project’s engineering and environmental specifications.
The deposited material should behave as any existing inert material on the seabed. In shallow water parts of the route, algae should soon populate exposed surfaces, and in deeper water, where oxygen and light are deficient, the surface of the rock should eventually be populated by micro-organisms.
Boskalis/Tideway contracted for Nord Stream post-lay
The Nord Stream consortium has contracted the Dutch joint venture Boskalis-Tideway Offshore for post-lay rock placement.