Radish field in Fehmarnbelt

Photo by courtesy of Royal Danish Navy EOD Service

Bombs from the First and Second World Wars can still be found in the Baltic and surrounding areas, including Fehmarnbelt. Since 1980, however, only one bomb has been found and defused in the corridor where the alignment for the fixed link across Fehmarnbelt is planned.

This has been revealed in a survey prepared for Femern A/S by Rambøll/Arup. The investigations have been carried out as part of the geophysical and geotechnical examinations and build in part on observations conducted during surveys of the seabed and in part on historical data from German, British and Danish authorities.

Like other sea areas, Fehmarnbelt was cleared of mines after the end of the Second World War.  Nevertheless, from time to time unexploded devices, such as torpedoes and depth charges are found on the seabed, as are ship and aircraft that could conceivably contain different types of ammunition.

Moreover, during the period between the two wars and, especially after the Second World War, large amounts of surplus ammunition were dumped in the sea around Denmark, including the Fehmarnbelt.

Other types of ammunition occasionally wash ashore. In 2007, two swimmers were injured following contact with a phosphoric grenade found on a beach.

Over the past three decades, German and Danish authorities have reported sixteen finds of unexploded devices in the Fehmarnbelt. Most of these were found by fishermen. All detonators were subsequently made harmless by controlled explosions.

Before construction work for the fixed Fehmarnbelt link begins, some supplementary surveys of the seabed may have to be carried out to minimise the risk of running into old war material during excavation works.

The importance of such surveys was demonstrated during the construction work for the Øresund fixed link between Sweden and Denmark.

Although preliminary investigations had indicated that the risk of encountering old war material was limited, dredgers uncovered a number of grenades during dredging for the 4 km long immersed tunnel. A total of 16 detonators had to be defused.

Subsequent investigations revealed that the grenades had been dropped by British fighter pilots shortly after the end of the Second World War during a display near Copenhagen Airport. The target was an amphibious plane and although the pilots succeeded in sinking the aircraft, not all grenades hit their target.