An operation to remove the masts from a sunken cargo ship in the River Thames, containing 1,400 tonnes of unstable explosives onboard, will involve Royal Navy specialists.
It is believed that if the unexploded ordnance on the SS Richard Montgomery were triggered it could lead to the nearby oil and gas facilities in Sheerness being damaged, the Daily Telegraph reports.
A Ministry of Defence report said an explosion “would throw a 300 metre-wide column of water and debris nearly 3,000 metres into the air and generate a wave 5 metres high”.
The ship has remained a hazard in the shipping waters around Sheerness since it sank on 20 August 1944. Its cargo of explosives in the forward holds has not been unloaded.
Masts from the wreck of the SS Richard Montgomery, beached in the sands below, have been pictured poking above the water.
A no-entry exclusion zone extends around the wreck and a local port owner is responsible for marking it with warning notices attached to the masts. Protective buoys circle the ship.
The MoD was supporting the Department for Transport, which in turn has a contractor that will undertake the mast removal process over a two-month period.
MoD-assured experts were due to assess the best way of surveying the area, identify any objects of interest, decide which of those objects need further investigation, and ensure that the mast removal work can be undertaken as safely as possible.
Two Royal Navy specialists had been tasked with providing specialist survey and identification advice and expertise.
A recent Department for Transport survey found the ship’s three masts were deteriorating and in a poor state.
The MoD had warned that the unexploded ordnance could detonate if any of the ship’s masts collapsed.
Previously the ministry had offered to pay £5m to any company that was able to safely remove the masts.
Peel Ports, which operates Sheerness docks, is responsible for marking and guarding the wreck. The seabed was surveyed in October to check for spilled explosives before the dismantling of the masts begins.
An MoD document reportedly seen by the Telegraph said that in the worst case the masts collapse or removal operation could cause “an explosion impacting the local area including the nearby oil and gas facilities in Sheerness leading to mass damage and potential loss of life”.
A spokesperson for the Maritime and Coastguard Agency said the risk of a major explosion was “remote”.
Built in Jacksonville, Florida in 1943, the Richard Montgomery was originally used to take vital supplies to Europe and it sailed across the Atlantic in convoy.
The ship went aground on a sandbank after the captain was ordered to anchor off the Great Nore. The water was too shallow and the ship got stuck as the tide fell.
Attempts to unload the vessel were abandoned after stevedores and navy divers faced treacherous weather conditions and greater danger as the ship settled.
After years of sonar surveillance, divers were again employed on site during a 2003 survey which involved an ultrasonic hull thickness analysis.
An up-to-date assessment of the level of seabed support of the wreck was obtained and the status of a large crack in one of the main holds was obtained. In 2013, a hull thickness survey was repeated.