Specialists prepare biggest underwater WWII bomb detonation in Europe as over 750 locals evacuated

Polish naval sappers are to carry out the biggest ever underwater bomb disposal operation in Europe. Marcin Bielecki/PAP

The biggest underwater bomb disposal operation ever to take place in Europe in which one of the largest bombs of WWII will be made safe starts today near Szczecin in northwest Poland.

Polish Navy specialist divers are today starting to neutralise a British Tallboy bomb, which was one of the largest bombs dropped in World War Two and contains 2.6 tonnes of torpex explosive, the equivalent of 3.5 tonnes of TNT.

The divers are pioneering a special ‘deflagration’ technique to make the explosive safe, making it the first operation of its kind on such a scale anywhere in the world.

Over 750 locals have been evacuated from their homes.Marcin Bielecki/PAP

Special buses have been laid on to help with the evacuation. Marcin Bielecki/PAP

Lt. Commander Grzegorz Lewandowski, spokesperson of the Świnoujście 8th Coast Defence Fleet said: “No unit in the world, certainly on such a scale, has carried out this kind of operation.”

The operation to neutralise the massive bomb is extremely risky as it could detonate with the slightest movement.

Heavy equipment cannot be used due to the delicacy of the mission. Therefore, specialist divers will have to dig the Tallboy out of the sand where it sits at the bottom of the Piast Channel.

Poland’s Ministry of Defence released an image showing the location of the bomb and the range of its destruction.Ministry of National Defence

Any movement could trigger one of the three detonators in the bomb, which inexplicably did not go off when the bomb was dropped 75 years ago.

Adding to the difficulty is the fact that the bomb is lying 12 metres underwater, with little visibility and in fast-moving currents.

The sand in which the bomb is half buried can slide and shift easily, making detonation a real risk.

Two years ago, during dredging work on the beach in Dziwnówek, an excavator detonated an anti-personnel mine.

Lt. Commander Grzegorz Lewandowski, spokesperson of the Świnoujście 8th Coast Defence Fleet said: “No unit in the world, certainly on such a scale, has carried out this kind of operation.”Marcin Bielecki/PAP

If the Tallboy explodes, a seismic wave could threaten nearby port infrastructure, bomb shrapnel could even break through the water’s surface. Above ground, the bomb has a destructive range of two kilometres.

The unexploded shell was found last September by workers who were deepening the Piast Channel, which leads from the Baltic port of Świnoujście in north-west Poland towards the large Szczecin Lagoon.

The huge ordinance was identified as a Tallboy, a seismic bomb designed and used by the British to attack underground targets and one of the largest bombs ever dropped in the war.

When it detonated an earthquake effect would shatter its target.

The British Tallboy bomb was one of the largest bombs dropped in WWII and contains 2.6 tonnes of torpex explosive, the equivalent of 3.5 tonnes of TNT.Public domain

The bomb in Szczecin was dropped by the RAF Dambuster Squadron on April 16, 1945 when it carried out a raid on the German cruiser Lützow, which was anchored in the channel.

It missed its target and sank to the bottom of the channel.

Polish naval sappers have now been left with the task of carrying out the biggest ever underwater bomb disposal operation in Europe.

Michał Jodłoski, commander of the 41st Demining Team from the 8th Coastal Defence Flotilla in Świnoujście said: “Tallboy bombs have already been neutralized in Germany, Norway, France and elsewhere, but these were operations on land. We are talking about neutralizing such a large object in water.

The bomb was dropped by the RAF Dambuster Squadron on April 16, 1945 when it carried out a raid on the German cruiser Lützow, which was anchored in the channel.Public domain

“There are not many unexploded bombs of this type in the world, because these bombs were constructed in such a way that they detonated. Therefore, the fact that it did not explode was a big surprise.”

Why the bomb did not explode seventy-five years ago is a mystery. It was designed to hit the target and only explode a short while later using a triple fuse system to make sure the bomb exploded.

“From the RAF reports, it appears that before the bomb was dropped, the bombs were properly armed. The crew did not report any problems,” Jodłoski said.

The whole operation is extremely complicated and took a year to plan as nobody has ever neutralised a Tallboy underwater before.

The specialist divers will have to dig the Tallboy out of the sand where it sits at the bottom of the Piast Channel.12th Minesweeper Division

12th Minesweeper Division

12th Minesweeper Division

During the year, nearly 400 explosives and dangerous items were removed from the area. These contained a total of three tons of TNT and included sea mines, depth charges and artillery shells.

The operation will be carried out in two stages. The first one will be the riskiest.

Over one metre of sand will be dug away to level the ground to expose the bomb. During this stage, any movement could trigger the detonators in the bomb.

Bringing the bomb to the surface and taking it out to sea is not an option as it would have to travel through Świnoujście, threatening the whole town.

Michał Jodłoski, commander of the 41st Demining Team from the 8th Coastal Defence Flotilla in Świnoujście said: “There are not many unexploded bombs of this type in the world, because these bombs were constructed in such a way that they detonated. Therefore, the fact that it did not explode was a big surprise.”8th Coastal Defence Flotilla

Therefore, the specialist divers decided to use deflagration which  involves the controlled burning of the explosive inside the bomb below the detonation threshold.

If the plan is successful in this case, the surface of the water will only be disturbed slightly, and a few bubbles may appear.

The advantage of the deflagration method is that it can be carried out remotely, which protects the lives of people participating in the operation.

However, if the material explodes it could cause a lot of damage. Nearby is the main Swinoujście ferry crossing and a road bridge leading to the island of Karsibór. An explosion could cause millions of zlotys of damage.

Since being discovered, nearly 400 explosives and dangerous items have been removed from the area. These contained a total of three tons of TNT and included sea mines, depth charges and artillery shells.12th Minesweeper Division/Poznan University of Technology

From 7 am and until 5 pm from Monday to Wednesday over 750 nearby inhabitants will be evacuated.

Thursday and Friday are reserve days in case of bad weather or other unforeseen circumstances.

Once the explosive has been neutralised, the shell will be taken to sea and destroyed.

The Dambuster Squadron's attack on the Lützow can be seen HERE, from 1'00 onwards