Prior to dredgework for beach suppletion ADEDE was contracted by van Oord to conduct a Side Scan Sonar and magnetometry UXO survey of the dredging area.

During World War One and Two German Navy and merchant shipping were forced to sail close to the shores of friendly and occupied territory, making these areas a prime target for allied mining. These mines are no longer triggered by shipping or mine countermeasures but they can still explode when handled, lifted or subjected to vibration. Just after WW2 priority lay in opening shipping lanes, not enabling safe dredging.

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Side scan sonar image with suspect cylindrical object

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EOD diver ready for inspecting the suspect object. He wears a helmet with radio, camera and torch. Air is surface supplied.

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Still from a helmet camera. A diver fits a sonar device to the mine for the Royal Dutch Navy’s destruction team for easy localisation.

During the survey several suspect targets were inspected by our dive team and two were positively identified as British A-MK1 influence mines. We prepared these for detonation by the Royal Dutch Navy. Next to the sea mines we found an aircraft bomb, most likely jetissoned by a crippled bomber. After the survey and clearance mission dredging continued without delays as a result of UXO.

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AUV

The Autonomous Underwater Vehicle is a robotic vehicle which carries side scan- and multibeam sonar and can be equipped with a towed magnetometer.


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Marine magnetometer

The G882 towed magnetometer system detects ferromagnetic anomalies on and under the sea bed.


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Towed side scan sonar

The towed side scan sonar is used for making images of the water bed, usually in deep water and large project areas.