SS Richard Montgomery - Status and Risk

Status and Risk

Because of the presence of the large quantity of unexploded ordnance, the ship is monitored by the Maritime and Coastguard Agency and is clearly marked on the relevant Admiralty Charts. In 1973 it became the first wreck designated as dangerous under section 2 of the Protection of Wrecks Act 1973. There is an exclusion zone around it monitored visually and by radar. The exclusion zone around the wreck is defined by the following co-ordinates:

• 51° 28’ 04” N 00° 47’ 12” E
• 51° 27’ 57” N 00° 47’ 22” E
• 51° 27’ 50” N 00° 47’ 11” E
• 51° 27’ 58” N 00° 47’ 01” E

According to a 2008 survey, the wreck is at a depth of 15 m (49 ft), on average, and leaning to starboard. At all states of the tide, its three masts are visible above the water.

The Maritime and Coastguard Agency nevertheless believe that the risk of a major explosion is remote. The UK government's Receiver of Wreck commissioned a risk assessment in 1999, but this risk assessment has not been published. The Maritime and Coastguard Agency convened with local and port authorities to discuss the report in 2001 and concluded that "doing nothing was not an option for much longer."

An investigation by New Scientist magazine concluded in 2004, based partly on government documents released in 2004, that the cargo was still deadly, and could be detonated by a collision, an attack, or even shifting of the cargo in the tide. The bad condition of the bombs is such that they could explode spontaneously. Documents declassified shortly before revealed that the wreck was not dealt with immediately after it happened, or in the intervening 60 years, due to the expense.

According to a survey conducted in 2000 by the United Kingdom Maritime and Coastguard Agency, the wreck still held munitions containing approximately 1,400 tonnes (1,500 short tons) of TNT high explosive. These comprise the following items of ordnance:

• 286 × 2,000 lb (910 kg) high explosive "Blockbuster" bombs
• 4,439 × 1,000 lb (450 kg) bombs of various types
• 1,925 × 500 lb (230 kg) bombs
• 2,815 fragmentation bombs and bomb clusters
• Various explosive booster charges
• Various smoke bombs, including white phosphorus bombs
• Various pyrotechnic signals

One of the reasons that the explosives have not been removed was the unfortunate outcome of a similar operation in July 1967 to neutralize the contents of the Kielce, a ship of Polish origin, sunk in 1946 off Folkestone in the English Channel. During preliminary work the Kielce, containing a comparable amount of ordnance, exploded with force equivalent to an earthquake measuring 4.5 on the Richter scale, digging a 20-foot-deep (6 m) crater in the seabed and bringing "panic and chaos" to Folkestone, although no injuries.

According to a BBC news report in 1970, it was determined that if the wreck of the SS Richard Montgomery exploded, it would throw a 1,000-foot-wide (300 m) column of water and debris nearly 10,000 feet (3,000 m) into the air and generate a wave 16 feet (5 m) high. Almost every window in Sheerness (pop. c20,000) would be broken and buildings would be damaged by the blast. However, news reports in May 2012 (including one by BBC Kent) stated that the wave could be about 4 feet (1 m) high, which although lower than previous estimates would be enough to cause flooding in some coastal settlements.

When the condition of the munitions was originally assessed there was concern that copper azide, an extremely sensitive explosive, would be produced through reaction between lead azide and copper from fuze components (lead azide would react with water vapour, rather than liquid water, to form hydrazoic acid, which could react with copper in the detonating cap to form copper azide).

The Maritime and Coastguard Agency (MCA) said in 1998, "as the fuses will probably all have been flooded for many years and the sensitive compounds referred to are all soluble in water this is no longer considered to be a significant hazard."

Critics of government assurances that the likelihood of a major explosion is remote argue that one of the fuzes of the 2,600 fuzed-fragmentation devices could become partially flooded and undergo the reaction producing copper azide. A knock, such as caused by the ship breaking up further, or a collision on the busy shipping lane, could cause the copper azide to explode and trigger an explosive chain reaction detonating the bulk of the munitions.

The wreck site has been surveyed regularly since 1965 to determine the stability of the structure, with a diver survey being completed in 2003. High-resolution multi-beam sonar surveys in 2005 and September 2006 found that there had been no recent significant movement of the wreck.

Surveys undertaken in 2008 and 2009 by the MCA, and reported in September 2011, showed that the ship was continuing to deteriorate structurally, with accelerated deterioration in some areas and new cracks appearing in the bow section of the wreck. The report states that "Whilst significant structural collapse does not appear to be imminent, surveys suggest that this prospect is getting closer." The increasing calls for a new airport in the Thames estuary would mean a solution would have to be found for removing the wreck, or at least making it safe, should the airport be built.

A May 2012 report into the condition of the wreck issued by the Department for Transport found that, while there had been little change in 2009-2010, the future was uncertain due to the "dynamic nature" of the surrounding environment. Mayor of London Boris Johnson said that engineers had found the wreck would not prevent construction of an airport, and the wreck area would have to be considered. The co-chair of the Lib Dem committee on transport, Julian Huppert disagreed saying "This report shows the ship’s slow deterioration is continuing with the lethal cargo still on board," and "This must surely put an end to the bonkers idea of building an airport in the Thames estuary." A DfT spokesperson said that the ship remained stable, and the likelihood of an explosion was remote; the matter of the ship was unrelated to the ongoing development of the aviation strategy.