Baltic States – CIS, Energy, EU – Baltic States, EU – CIS, Gas

90 years have already passed since the end of First World War, and almost 65 years - since 1945. There are no more mines, which could be in combat readiness floating at anchors, in the Baltic Sea. But the mines, which are lying on the sea-bed, are still dangerous to the shelf development, fishery, underwater engineering works, cabling and construction of pipelines.

Mine-clearance operations are very complicated and expensive. The effectiveness of such operations could be provided only by joint efforts of many countries. Since 1996 countries of the Baltic Sea region in collaboration with other NATO – member countries annually conduct operations to clear the bottom of the Baltic Sea of ordnance. During this time period about 1000 ordnance units were neutralized. The most large-scale mine-clearance operations are the multinational naval exercises “OPEN SPIRIT”, which are annually conducted in the waters of Latvia, Lithuania and Estonia. There were warships from Estonia, Lithuania, Latvia, as well as from Belgium, Dane, Finland, France, Germany, Netherlands, Poland, Russia, Sweden and UK participating in this naval exercises.

The basic ordnance disposal method, used in these exercises, is following: by the means of specially developed remotely operated vehicle a small charge is placed at the sea-bed near the detected ordnance. Then from a surface vessel, which is located on a secure distance from the object, the detonation of charges is carried out. During the last “OPEN SPIRIT” exercises in 2008 and 2009 demolition charges were delivered to mines by divers.

The gas pipeline Nord Stream will be laid across the Baltic Sea from Russia (Vyborg) to Germany (Greifswald). It will be 1200 kilometres long and will consist of two parallel lines. The first pipeline, with a transmission capacity of 27.5 billion cubic metres of gas a year, is scheduled to be completed in 2011. The construction of the parallel pipeline, which is due to be completed in 2012, will increase the annual capacity to around 55 billion cubic metres.

In order to guarantee safety during the construction and operation of the pipeline, the evaluation of all ammunition units, detected in the area of construction, has been performed.

Any mine is safe until it is disturbed. However, the “Nord Stream” Company needs to clear the pipeline construction corridors of all tips of submersed explosive objects. Primarily the mine-clearance should be performed inside the safety corridor of 25 metres, where the gas pipeline will run. The safety distance of 25 metres had been chosen on the basis of the engineering analysis of the effects of the underwater explosion. This analysis was performed by “Nord Stream” design contractor, SES (Saipem Energy Services) company, and was approved by the certifying body Det Norske Veritas (DNV).

It happened during the World War II. On November, 27, 1943, a soviet bomber “A-20 Boston” of the 1st Guards Mine-Torpedo Aviaregiment (the commander of the crew was Guards Captain Peter Letunovsky) has attacked a German heavy floating battery “Robert Muller ” across of the Ovishy Lighthouse near the southern entrance to the Irben Straight. The torpedo 45-36 АН (the warhead– 200 kg of explosives) which was dropped from the aircraft went to the depth and exploded after hitting the sea-bed at a distance of 20 meters from the German ship’s side. The torpedo explosion did not cause damage to the floating battery “Robert Muller”. If we take into account that the sea depth in this area was about 13, this episode indirectly confirms the relative safety of the security distance of 25 metres chosen by Nord Stream. It should be also noted that the steel pipes with wall thickness of 27-41 mm (tested for internal pressure of 220 Bar) are more resistant to damaging factors of the underwater explosion than a ship’s construction.

The next problem, which should be solved during the construction of the gas pipeline, is the safety inside the anchor corridor. The installation of the pipeline will be carried out from the pipe-laying vessel, the precise positioning of which is provided by 12 sea anchors. However, the company Nord Stream has taken a decision to use in pipe-laying in the Gulf of Finland a dynamically positioned vessel. Dynamic positioning is a computer controlled system to automatically maintain a vessel’s position and heading by using its own propellers and thrusters. Such vessel does not drop anchors, thus eliminating the necessity of mine-clearance inside the anchor corridor. When the pipe-laying in the Gulf of Finland will be completed, the anchored lay barge will be in use again.

By December, 2009, Nord Stream has identified 30 munitions that have to be cleared within the security corridor in the Finnish EEZ and six items in the anchor corridor or adjacent to those that have to be cleared from the security corridor. In the Swedish EEZ, only one munition must be cleared from the security corridor and one in the anchor corridor. In the order of 30 will be cleared in Russian waters. Clearance is performed in two phases, first along the security corridor; followed by the clearance of selected munitions within the anchor corridor.

The partner of Nord Stream in all mine-clearance activities is BACTEC International Limited - a UK based explosive ordnance disposal (EOD) and mine-clearance Company. In order to ensure ecological and technological safety a plan was developed, which establishes the parameters for the monitoring program of the clearance works, along with pro-active mitigation measures.