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Invisible danger underground
Even decades after the end of the Second World War, an invisible threat lies dormant at the bottom of many German waters: sunken bombs, grenades and ammunition remnants. These contaminated sites are often hidden under the sediments of the last 80 years – a latent danger to people, the environment and planned remediation measures. The safe recovery of these ordnance is a technically complex and interdisciplinary task – and a mandatory prerequisite for any sustainable water remediation.
A project with depth: explosive ordnance clearance as a first step
A current project by M&P Ingenieurgesellschaft – a member of the SIERA Alliance in Hanover exemplifies the challenges.
In a rainwater retention basin in need of renovation, the contaminated sediment was to be removed. But before the suction dredger could move in to remove sediment, a thorough exploration of the bottom of the water was necessary – the basin already existed before the Second World War.
With the help of state-of-the-art water probing, a specialist company examined the bottom of the water from the surface using a high-resolution 5-channel system. The aim was to identify suspicious structures in and under the sediment.
The evaluation quickly confirmed that remediation was not possible without prior explosive ordnance clearance. In close cooperation with the internal departments of Explosive Ordnance, Nature Conservation and Water Remediation, M&P developed a comprehensive clearance concept including tender documents as well as a landscape conservation plan according to the specifications of the lower nature conservation authority.
From suspicion to controlled demolition
The clearance began with a salvage complex consisting of a 15 × 15 m pontoon with hydraulic excavator and two groups of divers. In addition to small metallic objects, larger, deeper points of suspicion were also discovered during the preceding sounding.
The inspection by divers confirmed the worst suspicion: It was a five-hundredweight bomb with an intact long-term detonator.
The explosive ordnance recovery service and the fire brigade as the hazard prevention authority reacted immediately – a restricted area was set up, emergency services were coordinated and, after the successful evacuation of the residents, a controlled demolition was carried out on site.
A widespread problem – and a central task
Such finds are not isolated cases, but reflect a widespread problem of urban waters. Explosive ordnance clearance is much more than a safety-relevant intermediate step: the future of the water body can only begin when the explosive past has been eliminated – through the removal of contaminated sediments, the restoration of ecological and water management functions and the recovery of valuable natural areas.
Conclusion: Security creates the future
The experience from Hanover shows how essential interdisciplinary planning and technical precision are for the safe remediation of polluted waters.
With projects like this, M&P Ingenieurgesellschaft – a member of the SIERA Alliance – makes an important contribution to a sustainable and safe approach to our environment.
