and so was heavily mined. After the warAllied countries took munitions confiscated from Germany and dumped them in the Baltic Seawhich at the time was considered the best means of disposal.
” Mines were laid in the Baltic Sea during the First World War and munitions…
Of the munitions remaining in the Baltic todaytwo broad categories are of primary concern for Nord Stream in the construction and operation of its pipeline: chemical munitions and conventional munitions.
A number of organisations and authorities regularly sweep discreet areas of the Baltic Sea for munitions and evaluate the impact of these munitions on the Baltic Sea. Among those are authorities and institutions that have accumulated vast knowledge in many years of dealing with the issue regularlymostly in connection with fishingand the combined navies of NATO members. HELCOM (the Helsinki Commission) has produced several reports on dumped munitions and stresses the need to continue researching the subject. HELCOM also reports that no munitions found in the Baltic have ever been unintentionally detonated. Nor has there been any accident during the handling of found munitions.
In this contextNord Stream views its rigorous surveys as a considerable contribution to what is known about munitions in the Baltic Sea. The proposed routeincluding two 15m wide installation corridorshas been planned to avoid known dump sitesand detailed surveys are being conducted to verify that it is safe to use.
The company approaches the issue of munitions in the Baltic Sea with no preconceptionsexcept that the issue cannot be dealt with lightlyand is therefore gathering all available information and opinions on the subject. This includes consultation of statutory authorities.
Nord Stream is researching the sea bed in a step by step approach in order to retrieve the most detailed data on the exact corridor where the pipeline will be laid whilstat the same timeensuring that no threatening objects are in the immediate surroundings of the pipeline route. The survey began with a 2km corridor that was screened for large objects and then progressively narrowed down to two 15m wide installation corridorswhere even objects as small as 10cm are identified.
Although there are no international regulations for dealing with munitionsNord Stream aims to set the highest standards and follows strict procedures defined by the leading survey specialists in the Baltic region. Survey work associated with the Nord Stream project has been divided into three phases: surveys in 2005 and 2006 with a focus on geophysical dataas well as a currentrigorous examination of the recently defined installation corridors in 2007 and 2008.
Surveying the pipeline route is one of Nord Stream’s major preparatory tasksand construction will not begin until it is entirely confident about the chosen route. North Transgas conducted the first survey of the seabed in 1998. This looked at possible routes across the Baltic seabed and covered many parts of the currently proposed route.
The first detailed screening of Nord Stream’s provisional route was carried out by PeterGaz in 2005. This was principally a geophysical survey to check the condition of the seabed across a 2km corridor and to look for obstacles such as wreckslarge boulders and trenches.
On the basis of the 2005 survey datatwo potential pipeline routes were selected. These were investigated in 2006 during a second seabed survey which covered a 180m-wide corridor along the entire length of the proposed pipeline.
This was a detailed geophysical survey that provided both engineering data and the image resolution required to identify munitions.
The instruments used were the best available at the timeand all ‘targets’ (objects that might possibly be munitions) were carefully recorded and added to the existing database of targets from the 2005 survey.
Nord Stream then deployed a remotely-operated vehicle (ROV) to inspect each target within 20m of the route in detail. In Swedish waters – one of the territories closest to the dump sites – there were more than a thousand targets.
Yet only one was potentially munitions-related (believed to be a mine release mechanism). In the Gulf of FinlandNord Stream found several suspect targetsincluding two mines (one deliberately sunk).
A few potential targets were located near the known chemical dumping area off Bornholmbut none were positively identified as related to chemical munitions. Nord Stream recorded the locations of these unresolved targets and passed the information on to the appropriate authorities for further investigation.
As a result of the 2005 and 2006 surveysonly two targets were clearly identified as minesand only one is thought to still be intact.
The other targets investigated were found to be items naturally occurring on the seabed or man-made itemssuch as: boulders; shopping trolley; oil drums; rubber hoses; peat bags; mine release mechanisms (non-explosive); a high per centage of the objects found were discarded white goods.
Nord Stream approached the 2005 and 2006 surveys without preconceptions about what it might find on the seabed along the proposed route of the pipeline and in adjacent areas.
Based on the results of these detailed surveysit is confident that munitions do not present a significant obstacle to the construction and safe operation of the pipeline. Howeveranother more detailed survey is currently being conducted to further investigate the two installation corridors along the proposed route and ensure this opinion is justified.
During the year 2007Nord Stream undertook measures to optimise the proposed route of the pipelines based on a number of factors. Once the two installation corridors were determinedNord Stream began preparations to survey both paths of exactly15m width each using the most precise investigative tools available on the commercial market.
Since July 2007Nord Stream has been conducting a detailed and targeted third surveyin three distinct stages.
The first stage employs technology such as The sub-bottom profiler can penetrate deep into the material at the sea bottom to show a cross-section of the mudsilt and bedrock that make up the seabed. The magnetometer provides information on ferrous (iron-based) materials.
The second stage uses a 6.7m wide12-sensor gradiometer array mounted on a ROV to detect any ferrous (iron-based) metals on the seabed.
Whereas the 2006 survey used electromagnetic induction sensorsthe gradiometer array will provide better lateral coveragea higher detection rate and will allow full coverage of each installation corridor in two passes of the ROV.
The higher-range capability of the gradiometer array allows the detection of buried objects that may have penetrated the soft sediments. Concurrently with the gradiometer surveyvisual coverage of the seabed is attained via two underwater cameras that are also mounted on the ROV.
The gradiometer data are processed within a digital terrain model and matched with the data already collected. Objects are located and recorded for further visual inspection.
In the third stage Nord Stream revisits and visually inspects all targets within a 50m corridor for each pipe located during the previous two stages. This allows experts to examine and identify any questionable objects. Where appropriateNord Stream will liaise with experienced navy personnel to help identify such objects.
The 2007–2008 surveywhich has to date covered Howevera number of munitions-related objects and mines was encountered in the Gulf of Finland and reported to the responsible Finnish authorities. In close cooperation with Nord Streamthe authorities will decide on how to deal with these findings.
Depending on the surrounding seabed conditionsclearing single mines might be preferable to rerouting the entire pipeline.
Independent sources confirm that a multi-sensor approach to surveying is best practice. Multi-coverage high-resolution surveys of the seabed and automated data-analysis enable detectionclassification and localisation of munitions and similarly-sized objects with a high degree of confidence.
Deployment of different types of sensorsuch as the range that Nord Stream is usingprovides a variety of data which can be combined to produce a high-quality picture of the sea floorregardless of environmental conditions.
The instruments deployed by Nord Stream include state-of-the-art multi-beam systemsside-scan sonar systems working at high frequency a specially developed gradiometer array.
Once this work is completedNord Stream will have examined numerous objects along the route of the two designated installation corridors. The results ofand knowledge obtained throughthe munitions surveys will be provided to relevant authorities as part of the application process and will also be disseminated to interested organisations involved with research in the Baltic Sea.
In additionthe teams that subsequently lay the pipeline will be contractually obliged to install the pipeline within the installation corridors. Installation vessels that use multi-point anchor spreads will be required to perform anchor clearance surveys and An inventory of all suspicious targets and instructions not to disturb any possible finds will be maintained on the installation vessels throughout the contract period.
The scale of Nord Stream’s munitions surveys is unprecedentedand the company is doing its utmost to acquire and deploy the most sophisticated survey equipment available.
To ensure that its survey techniques follow recommended good practiceNord Stream has organised a seminar at which experts will have the opportunity to review present and past survey data and to recommend changes to procedures.
Nord Stream is aware of the multitude of munitions that have been disposed in the Baltic Seaand it takes the potential threat they pose extremely seriously. It has the capacitiesthe most current technology and unparalleled expertise at its disposal to manage this sensitive issue. Nord Stream is contributing – through these extensive examinations – to enhancing current knowledge of munitions finds in key areas of the Baltic Sea.
Nord Stream is thereby ensuring that future projectsincluding future pipelinesare planned with a heightened appreciation of the constraints associated with munitions. For further information please go to www.nord-stream.com
multi-beam echo sounders (MBES)high-resolution side-scan sonars (SSS)sub-bottom profilers and a magnetometer. Multi-beam echo sounders and side-scan sonars provide a detailed picture of the contours of the sea floor and of objects lying on the seabed.
94 per cent of the proposed pipeline routehas as yet produced no positive finds in the central/southern Baltic. This confirms the 2006 survey results.
inspect all targets that could interfere with the anchor patternso checking each seabed location before dropping anchor.
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