Tuesday, September 23, 2008

SS Richard Montgomery

Reading the Times this morning, I found out that the excellent plan to move London airport to a new island off the Isle of Sheppey in Kent has a major league hitch. To wit, the USS Richard Montgomery, the wreck of a World War II munitions ship still carrying 1400 tons of explosive in some 3000 tons of ordnance.

I see here not an obstacle but an opportunity. To build the proposed island needed to site the airport is a massive feat of civil engineering requiring the building of an artificial island over 6 Kilometres on a side. A good deal of excavation will be required, not least in the unstable and polluted silts off Sheerness.

Now to my semi educated eye, knowing the little I do on the subject, might it not be a good idea to build a huge soil and rock 'coffer dam' around the wreck to the planned island perimeter? It should be worth noting that the nature of the wreck means, according to a report by the UK Maritime & Coastguard Agency that "doing nothing was not an option for much longer". In other words, it's going to explode anyway as sea water infiltrates the fuses and detonators, so why not deal with it in a planned and careful manner? Build the coffer dam in the form of a perimeter wall some 50m thick, let's say to a height of 15m above the high water mark withe the wreck half a kilometre inside the southern perimeter. Build a sluice at the lowest point and let the next extreme low tide drain out the bulk of sea water. Block off the now redundant sluice with an earthern wall to the same thickness as the rest of the coffer dam, and pump out enough water to expose the very top of the upperworks of the wreck if these are not already awash. Set demolition charges and detonate at low tide to mitigate any shockwave in the water. Do not forget to stand well clear. Two miles should do the trick.

The 15m coffer dam, if shaped correctly, would deflect most of the blast energy upwards, and thus prevent blast /overpressure damage on the mainland. It would also contain most of the debris, limit damage to the nearby marine habitat, which would be destroyed by the wreck detonating on its own. It should also limit any fallout by 'shaping' the detonation rather than allow a disaster to happen on the north Kentish coast. Leaving a certain quantity of water in the enclosed perimeter would have a damping effect on the explosion which should inundate the coffer dam but mitigate any catastrophic effects upon the environment. Sheerness might not hear a thing, rather like this example, where local residents spoke of not hearing the largest civilian explosion ever.

Benefits; Big hole dug for underground airport infrastructure / landfill at minimal cost. Getting rid of dangerous wreck which is going to go up in smoke in the not too distant future anyway. Provides a lot of construction jobs while the global economy is in a downturn. Workers pay taxes, provides work for associated industries such as mining and construction equipment. Gets rid of a cubic Kilometre or two of non recyclable material and provides new land for an airport nobody else wants. All that and lots of work for Civil Engineers.

Looks like a win-win to me. Wonder if the US governments offer from 1967 to help make the wreck safe would provide extra project funding? Could be worth a try.

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