Hidden Dangers: The Legacy of Sea-Dumped Unexploded Ordnance

In the aftermath of past wars and conflicts, vast quantities of unexploded ordnance (UXO) were disposed of in what was considered to be the most convenient way available at the time: dumping them into bodies of water.

This practice, sometimes known as “sea dumping,” has left a dangerous legacy lurking beneath our oceans, lakes, rivers and canals. Today, these forgotten items are resurfacing, driven by a combination of environmental factors, hobbyists like magnet fishers, and government initiatives like Switzerland’s recent cash prize for removing munitions from its lakes.

The Historical Context of Sea Dumping

During and after the two World Wars, millions of tons of munitions were discarded in bodies of water worldwide. At the time, this practice was seen as a straightforward solution to dispose of surplus, obsolete, or damaged munitions. Governments adopted an “out of sight, out of mind” mentality, believing that dumping munitions far away and as deep as possible would negate any future risk. However, what seemed like a short-term fix has created long-term risks.

The dangers posed by sea-dumped UXO are multi-faceted. These munitions can still detonate, posing risks to marine life, fishermen, and the broader maritime community. Moreover, the chemicals and explosives within these munitions can leak, contaminating water sources and threatening ecosystems.

Despite these risks, the full extent of sea-dumped UXO is largely unknown, as records were either poorly kept or lost over time. In the UK, historic dumping sites were initially recorded, however, the Ministry of Defence has admitted to losing or accidentally destroying documents containing the locations, volumes and types of munitions that had been dumped.

This practice was largely brought to an end in the UK after the introduction of the 1972 London Convention which prohibited the deliberate sea dumping of munitions and other waste. The new legislation, however, did not require remedial actions for areas contaminated by earlier disposal activities.

Examples of UXO Sea Dumping Locations

While items of UXO have been disposed of in bodies of water worldwide, some sites are particularly notorious for the scale and potential risks they pose.

Beaufort’s Dyke

Located in the North Channel between Scotland and Northern Ireland, Beaufort’s Dyke is a deep trench extending up to 300 metres in depth. Its proximity to the UK made it a convenient location for disposing of vast quantities of surplus munitions after both World Wars. It is estimated that over 1 million tons of explosives and chemical munitions were dumped in Beaufort’s Dyke, including mustard gas, phosgene, and other toxic substances. The deep waters of the trench were thought to safely contain these materials, but over time, concerns have grown about the stability of these munitions.

In recent years, unexploded ordnance from Beaufort’s Dyke has been found washed up on nearby shores, highlighting the ongoing risks posed by this underwater dumping ground.

Other Notable Dumping Sites

Baltic Sea: The Baltic Sea is another area with extensive dumping of chemical munitions after World War II. Tens of thousands of tons of chemical weapons were sunk here by the Allies, and today, they pose a serious environmental threat, as the chemicals are slowly leaking into the surrounding waters.

Skagerrak Strait: Situated between Norway and Denmark, the Skagerrak Strait was used to dump large quantities of chemical and conventional munitions. The area is notorious for its difficult underwater terrain, which complicates efforts to map and remove these dangerous remnants.

North Sea: Various locations in the North Sea were used for dumping munitions, including off the coast of Belgium and the Netherlands. These sites are particularly concerning due to their proximity to heavily trafficked shipping routes and offshore energy installations.

The Rise of Magnet Fishing and its Role in UXO Discovery

The dumping of munitions was not limited to oceans but extended to rivers, lakes, and canals- bodies of water that were never intended to be drained.

In recent years, magnet fishing – a hobby that involves using a powerful magnet to recover metal objects from bodies of water – has gained popularity. While enthusiasts often pull up historical artefacts, coins, and scrap metal, some have also unintentionally retrieved dangerous items of UXO.

Accidental discoveries by magnet fishers have led to evacuations, bomb squad interventions, and increased public awareness of the dangers that lie beneath the water’s surface. It was reported that in 2021 alone, explosive ordnance disposal teams responded to 150 callouts to devices discovered by magnet fishers.

A few examples from the last couple of years include a rifle grenade being discovered by a magnet fisher in St Ives, a suspected tank round found in an Oxford river and a “huge haul” of Home Guard weapons discovered in Leamington Spa by a magnet fishing social group based out of Birmingham.

Switzerland’s New Approach: A Cash Prize for Safety

Recently, Switzerland made headlines with its novel approach to tackling underwater munitions. The Swiss government is offering a cash prize of £45,000 for the three best ideas on how to safely remove unexploded ordnance from its lakes.

For years the Swiss military used lakes Lucerne, Thun and Neuchatel as dumping grounds for old munitions, believing it was safe to dispose of them there. It is estimated that there are 3,300 tonnes of munitions in Lake Lucerne, and 4,500 tonnes in the waters of Neuchatel, which was used for bombing practice by the Swiss Air Force until 2021. Some munitions are believed to be at depths of 150 to 220 metres, but in Lake Neuchatel, they are reported at just six or seven metres below the surface.

Interference with Energy Infrastructure Development

As the demand for renewable energy sources continues to grow, offshore energy development has become increasingly vital, however, the legacy of sea dumped UXO poses significant challenges to the expansion of this industry.

Firstly, the construction and maintenance of these installations require extensive underwater operations, such as drilling, anchoring, and cable laying, which can inadvertently disturb UXO. The risk of detonating these munitions poses a severe threat not only to workers and vessels but also to the infrastructure itself, potentially causing delays, costly damage, or even catastrophic accidents.

Moreover, the corrosive marine environment can cause the deterioration of munitions casings, increasing the likelihood of chemical leakage into the water. These chemicals, often highly toxic, can disrupt local ecosystems and pose additional risks to energy projects that rely on the surrounding environment.

The threat of UXO necessitates comprehensive risk assessments and potentially expensive mitigation strategies before any offshore energy development can commence.

A Path Forward: Addressing the Legacy of Sea-Dumped UXO

The dangers of sea-dumped UXO are clear, and governments, environmental groups, and private companies must work together to locate, assess, and safely remove these underwater threats.

One such initiative is the work of OSPAR, the mechanism by which 15 governments and the EU cooperate to protect the marine environment of the North-East Atlantic. OSPAR has been instrumental in collecting the best available information on dumping sites, including their estimated locations and contents, where known.

For those involved in activities like magnet fishing, it’s crucial to recognise the potential risks and to report any suspicious finds to the authorities. While the thrill of discovery is understandable, safety must always come first.

Get in touch with our Commercial Team

At Brimstone UXO, we are dedicated to addressing the complex challenges posed by UXO, both on land and underwater. If you have an upcoming construction project and you need to get your site assessed for UXO risks, contact our Commercial Team at enquire@brimstoneuxo.com or 020 7117 2492. You can also fill out a contact form here.

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