a bigger bang

The army has been clattering away today on the ranges.  The patter of machine gun fire and the repeated deeper rattle of something that might have been a rarden cannon, the isolated pops of rifles or small arms fire, and something so big it made the house shake and brought the Systems Administrator scurrying downstairs to see if there was somebody at the front door.

Yesterday the Royal Navy had to carry out controlled explosions on 'about nine' anti-aircraft shells washed ashore at Westcliffe-on-Sea, part of Southend-on-Sea.  There was a photo on the BBC Essex website of a chunky little explosion, half a mile from the seafront.  The shells were described as being corroded but still live.

It looked like quite a bang, but as nothing compared to the one we'd get if the SS Richard Montgomery ever went up.  The media is spasmodically interested in the Montgomery.  The BBC ran a story last June, questioning whether its presence ruled out an airport in the Thames estuary, but in general it doesn't get much of a mention.  Those in favour of Boris Island, or the Thames Hub Airport on the Isle of Grain, seem to believe that the wreck of the Richard Montgomery is a boring technical detail, which could easily be dealt with during the course of airport construction. Wikipedia's list of bullet points giving the disadvantages of a Thames estuary airport puts it in twelfth place, behind the incidence of fog and the risk of bird strike.

Could it be easily dealt with?  Who knows?  Nobody, really, not even Boris, or Sir Norman Foster, because nobody knows what happens to 1400 tonnes of nitroglycerine explosive after it has been submerged in seawater for seventy years, and that is what was on the SS Richard Montgomery when she sank.  Laden with munitions and waiting to form part of a convoy, she dragged her anchor, touched on a sandbank off the Medway, stuck, and broke her back as the tide ebbed and before salvage crews could remove all her cargo.  And there she stays.  There is an exclusion zone around her, marked with buoys, and at low water her masts still stick up above the water.  We have sailed past her, and it is a desolate, eerie, spine-chilling and skin-creeping spot.

The explosives are reckoned to be live and unstable, though by now their original operating mechanisms may well be rusted away.  Nobody knows whether attempts to move them would trigger an explosion, and there doesn't seem to be any way of finding out, short of trying it and seeing what happens.  It's not as though there is another ship containing nitroglycerine that's been marinading in sea water for seventy years, in a more convenient position, that we could practice on first.  If someone were to design a computer model of what should happen, they would have no means of verifying it.  Estimates of the damage that would occur if the SS Richard Montgomery went up vary wildly.  The resulting wave could be sixteen feet high, or four feet, depending on who you believe.  Local legend has it that the blast would flatten the Isle of Grain power station (though that was mothballed a while back anyway so it might not matter so much) and smash every window in Southend.

You can see why Boris doesn't want to think about it.