Undersea arms dump is giving up its secrets

Undersea arms dump is giving up its secrets

12 August 2015

THE elderly couple walking on Murlough beach near Dundrum were curious about the rusty metal object lying half buried in a pool of water.

About ten inches long and four inches in diameter and cylindrical object was solid and resisted the man’s attempts to move it with his walking stick. His efforts intensified until he was gripping the walking stick with both hands, trying to dislodge the object which was firmly ensconced in the wet sand.

Watching her husband’s efforts the woman recalled reading about increasing numbers of world war shells which were being washed up on Co Down beaches and being discovered by members of the public. When she shared her thoughts with her husband his increasingly violent attack on the object immediately ceased and the couple quickly telephoned the Coastguard.

The object turned out to be a four inch mortar from the second world war which was part of over one million tonnes of military ordnance dumped in the Irish Sea in 1945. The South Down Coastguard team cordoned off the beach and an army bomb disposal team blew up the device where it lay. 

The Coastguards quizzed the army experts about the likelihood of such devices exploding if disturbed on the beach.“You could hit a mortar like this 1,000 times and it wouldn’t go off but you could hit the next one just once and it could explode,” said the bomb disposal sergeant, who quickly added there were no recorded incidents of members of the public being injured by exploding ordnance from underwater dumps.

The incident occurred last summer but in the past two weeks four more unexploded mortars have been found on local beaches — two on the beach between Tyrella and Ballykinlar and two on Murlough, including one last week. 

It is accepted that the bombs have come from a deep trench in the Irish Sea into which massive quantities of munitions and ordnance were dumped at the end of the world wars.

In 1945 the UK government faced a huge post war problem in the shape of two million tons of army and RAF ordnance sitting in stockpiles in the UK and Europe which was no longer needed.

The government had used sea dumping at the end of the First World War and 27 years later it was decided again that underwater disposal was the safest and most efficient method of disposal.

There were several underwater ordnance dumps but by far the largest was in Beaufort’s Dyke, a long narrow trough between Scotland and Northern Ireland. The trench measures almost 30 miles long and two miles wide with a depth in excess of 200 metres.

Nearby was the military port at Cairnryan which had been built during WW2 and which became a focal point for the sea-dumping of excess ordnance.

There are limited records of just what was dumped in the Dyke after WW2, and no records exist for the ordnance disposed off after WW1, although it is accepted that shells containing deadly mustard gas were among the munitions disposed off.

However, a record does exist for 1945-46 which shows among the items dumped in the Irish Sea were 500lb high explosive bombs, many different sizes of mortars, grenades, rockets, cluster bombs, anti aircraft shells and rockets containing the poisonous gas, phosgene. In July 1945 alone over 14,600 tonnes of phosgene-containing rockets where dumped in Beaufort’s Dyke.

Also dumped were millions of rounds of small arms ammunition which were encased in concrete and which are regularly found by metal detectors on local beaches, particularly in the coves between Ardglass and Ballyhornan.

It is also believed that German munitions such as torpedoes and machine gun ammunition from captured German U-boats was also dumped.

The dumping was usually carried out by 24 tank landing craft along with four coasters and a number of former trawlers. Larger vessels were also used, several of which were scuttled with cargoes of chemical weapons in deep water to the west of Scotland and off Donegal. On occasion, cargoes destined for deep water disposal were diverted to Beaufort’s Dyke because of bad weather.

There appears to be little doubt that many of the dumping operations were carried out by crews only too keen to get rid of their unwanted and hazardous cargo at the first opportunity. While they may not have just dumped them indiscriminately, the patterns seen in the present day charts do suggest they were offloaded at the earliest opportunity in a number of cases.

It should also be remembered that the locations were fixed by traditional sighting methods at the time, not be the highly accurate GPS methods used today. On moving vessels, with no land references in sight, positions would only have been known to within a few miles at best.

Although there are no accurate records, it is accepted that at least one millions tonnes of munitions passed through Cairnryan for Beaufort’s Dyke. As late as 1955 coasters were still bringing cargoes of munitions from dumps in Normandy in France to be disposed of in the north channel and this dumping did not end entirely until the early 1970s.

In the mid 1990s the first items from the undersea munitions dump began washing ashore on beaches in Galloway in Scotland and Co Antrim. These were phosphorous boiler lighters which are perfectly safe when submersed in water but which can spontaneously combust when they dry out. 

The discovery of these stranded devices coincided with the laying of a submarine gas pipeline between Scotland and Northern Ireland. The pipe passes to the north of the Beaufort’s Dyke explosives disposal site and it is believed the operation disturbed some of the ordnance.

The government commissioned a survey to determine the distribution of the munitions within and around Beaufort’s Dyke and then establish whether the dumping had contaminated the seabed, fish or shellfish.

The survey confirmed that munitions were distributed over a wide area which extended outside the boundary of the charted dump site. Samples of the seabed sediment and fish and shellfish were analysed but none contained the chemical warfare agents phosgene or mustard gas or explosive of propellant residues.

The survey means the restricted area around around Beaufort’s Dyke has been extended and any new cables or pipelines will have to pass further north or south to avoid the area.

In early 1997 the Beaufort’s Dyke munitions dump attracted controversy when researchers uncovered documents indicating that small quantities of low or intermediate level radioactive waste was dumped in the Dyke between 1953 and 1957. The material, mainly contaminated laboratory waste and radioactive luminous paint applied to clock hands, was put in metal drums and encased in concrete before being dumped.

It is believed that the mortar bombs which have been coming ashore along the Northern Ireland coast for several years were dumped in their original wooden storage boxes which have now corroded away leaving the individual bombs at the mercy of the strong tides in the north channel.

The discoveries in Co Down have all occurred within a few days of a storm and experts predict such finds will continue for the foreseeable future.

From the Coastguard the advice is simple. If you spot something on the beach which you’re not sure about don’t touch it. Dial 999 and ask for the Coastguard who can call on the army bomb disposal experts to either blow up the suspicious object or simply remove it from the beach.