b'INTERNATIONAL WATERSA Minefield Building the massive Nord Stream and Nord Stream 2"In addition to noise monitoring underwater, we also gas pipelines through the Baltic Sea has often provenmonitor water quality in those regions because they to be fraught with minefields. Not just political ones.are so sensitivelike underwater reefs where we have Real ones. sensitive areas of vegetation and fish are laying eggs," says Antti Lindfors of Luode Consulting. During World Wars I and II and the Cold War that followed, opposing navies jostled for advantage inHydrophones miles away from the blasts provide the Baltic. Harbors and channels were strewn withinsight on sound waves in the water, particularly minesestimates range from 80,000 to 150,000 ofaround seal reserves in Finland and Estonia. them, mainly in the Gulf of Finlandand littered with air-dropped bombs and depth charges. After theThe thorough monitoring protocol has demonstrated world wars, vast stockpiles of artillery shells and otherthat the bubble curtains are highly effective at ordnance were also dumped at sea.reducing noise from the explosions, and the uneven topography of the sea floor helps dampen noise and To safely build the Nord Stream and Nord Streamsediment disturbances, says Lindfors.2 pipelines, explosives experts had to clear mines along the route. For the vast majority, relocation"The effects are smaller in size, and in many areas, we and recovery were not considered viable options, socannot see impacts of elevated turbidity levels higher in-situ clearancedetonation on the seabedwasthan background variations," he notes. "The areas of employed. Some of the mines have charges asdangerous noise are smaller than predicted in the large as 300 kilograms (660 pounds), and theirEnvironmental Impact Assessment."detonation could have significant impact on wildlife. To minimize the damage to habitatLindfors acknowledges that the ordnance clearing and marine life, mine clearance has comeby the pipeline company does not address all the a long way since the old days of cuttinglegacy mine risks, but in a region where a mine anchor anchor lines and shooting the bobbingline is occasionally severed by drifting ice, and in an explosives from minesweeper ships. area of commercial fishing, every mine that is out of commission makes the sea\'s busy traffic and fishing Nord Stream 2 performed detailedareas safer.environmental assessments of the potential impact of munition clearance"The mine clearance operation benefits the whole to establish mitigation measures toBaltic Sea," he says.minimize the risk of permanent hearing damage to wildlife. Along the Nord Stream 2 route in the Gulf of Finland, ordnance experts used a remotely operated vehicle to identify mines and attach small explosive charges to them. Another vessel\'s crew laid special hoses around most of the mines to be cleared and pumped high-pressure air to create a curtain of bubbles that absorbed most of the concussive wave energy caused by the explosion. As with every other aspect of construction, Luode Consulting of Finland was on-hand with its monitoring equipment to ensure the effectiveness of the mitigation measures to protect wildlife. A technician inspects a find during munitions clearance operations. Nord Stream 2 conducted extensive surveys along the pipeline route to avoid unexploded ordnance (UXO)mines, bombs and dumped munitionswhenever possible.Nord Stream 2 / Axel SchmidtWhos Minding the Planet? 39'