Half of German city must evacuate after unexploded 1.8 tonne bomb found

About 45,000 people will be evacuated from their homes in Koblenz on Sunday while experts attempt to defuse a 1.8 tonne British aerial mine.

Two members of the bomb disposal unit stand next to the area where an aerial mine was found in Koblenz. On Sunday up to 45,000 residents will be evacuated as they attempt to difuse the 1.8 tonne bomb.

BERLIN // About 45,000 people will be evacuated from their homes in Koblenz on Sunday while experts attempt to defuse one of the biggest unexploded Second World War bombs found in Germany - a 1.8 tonne British aerial mine.

Authorities have designated a 1.8 kilometre security radius around the bomb, which means half the population of Koblenz will have to move out. Two hospitals, seven care homes for elderly people and the city's prison will have to be cleared in a major logistical operation that will also shut down the road and rail lines on both sides of the Rhine river.

It is one of a number of wartime bombs and weapons that have been uncovered in the Rhine river over the last week due to a sharp fall in water levels following an unusually dry November.

Disposal experts have defused one 250 kilogram and one 500 kilogram bomb in the Rhine near Koblenz in recent days, and have also been removing old munitions that have come to light.

The discoveries are a reminder of the deadly legacy of unexploded munitions that continues to plague Germany 66 years after the end of the Second World War.

An estimated 2,000 tonnes of American and British aerial bombs and other munitions are still found every year, usually during construction work, and evacuations and road closures occur almost every week.

Horst Lenz, the regional head of the bomb disposal service, who will be defusing the British bomb on Sunday, has 27 years of experience and said his job was getting more dangerous.

"The bombs are becoming more unstable over time," he told The National in a telephone interview. "Chemical vapours inside them are corroding the firing mechanisms."

The bomb has three detonators made of brass that are all still well preserved despite having been in the water for decades. "This isn't something we can do with remote-controlled apparatus, that would be far too dangerous. We have to screw the detonators out by hand," said Mr Lenz.

"These last few days have been among the busiest times we've ever had."

While the operation is routine to him and he doesn't foresee problems, there is always an element of uncertainty.

"We're not sure what type of firing pin they have," he said. "And we don't know what corrosion has been caused by the lead oxide inside."

Mr Lenz said he wasn't awed by the sheer volume of explosive he will be dealing with. "The explosive force is irrelevant for us. We're so close that just 100 grams would be deadly."

The bomb is in 40 centimetres of water, but it is being surrounded by 350 sandbags each weighing a tonne, and water will be pumped out of the area to enable Mr Lenz and his team to work in the dry.

Nazi Germany was first to launch air raids on civilian targets in the Second World War, with devastating attacks on cities in Poland and then on London.

The Allies mounted a five-year campaign of aerial bombardment during which they dropped 1.9 million tonnes of bombs in an attempt to destroy Germany's industry and crush civilian morale.

The allied raids killed an estimated 500,000 people. Koblenz became a target in 1944 and 1945, and about 90 per cent of the city was destroyed.

The country quickly rebuilt its cities after the war and authorities didn't have the time or the means to locate and dispose of a large part of that tonnage. Usually only especially sensitive areas, such as the ground around schools and hospital, were searched for bombs.

The hunt for unexploded bombs intensified in the 1990s when Britain and the US made aerial reconnaissance photographs available to German authorities, allowing them to pinpoint the location of suspected duds.