Final permission has been granted to Nord Stream AG to start construction of a natural-gas pipeline through the Baltic Sea. All permits required by the four countries through whose territorial waters or Exclusive Economic Zones (EEZ) the pipeline will pass: Russia, Sweden, Denmark and Germany are now complete, the activities are scheduled to start April 2010.

The offshore pipeline will link Russian natural-gas production facilities with consumers in the European Union via the Baltic Sea. It will consist of two parallel lines, 1,223 kilometres in length. The first, with a transmission capacity of around 27.5 billion cubic metres per year, is due for completion in 2011. The second is scheduled for completion in 2012, doubling annual capacity to around 55 billion cubic metres: enough to supply more than 25 million households in Europe. Total investment in the offshore pipeline is projected at 7.4 billion Euros.

The hostile environment of the Baltic Sea will make great demands on land and hydrographical surveyors and their instruments. Temperatures varying from less than -35ºC to over +35ºC (-31ºF to 95ºF) make this region one of extreme weather conditions. Last winter several ships became icebound and had to be rescued by icebreakers.

A typical survey instrument such as a tachymeter will operate within a temperature range of -20°C to +50°C (-4°F to +122°F). Some manufacturers offer special arctic versions which will operate at temperatures as low as -5°C (-31°F). Typical GNSS antennae operate within a range of -40°C to +70°C (-0ºF to 158ºF). Special preparations will have to be made to protect man and machine.

Onshore construction works and preparatory hydrographical surveys are already underway, some having revealed an unexpected number of twelve hitherto unknown shipwrecks in the Swedish EEZ.

Photographed is the Solitaire, the largest pipelay vessel in the world.