Posted on 01.04.2014 - 07:00 EDT in ROV NEWS by DT_Sam
They have lain submerged off the coast of Britain for more than 70 years, but three unexploded German bombs were finally disposed of by a small device that looked like a Hubba Bubba chewing gum packet.
The 50kg devices barely shook the surface of the water as they were blown up by British explosives experts, although any marine life in the area may have got a bit of a shock as the boom radiated through the depths.
They had been dropped by the Luftwaffe during one of thousands of waves of bombing raids in the Blitz, but mercifully fell short of their intended target on land. The bombs, which were still live, had been found near Gwynt y Môr windfarm, eight miles off Pensarn, in January.
Disposal specialist Dave Welch has told how his firm, Ramora UK – working with windfarm developers RWE Innogy UK – used a piece of pink coloured Semtex to make the Nazi devices safe.
He said: “It went according to plan. We use a block of our own explosive, normally pink Semtex in an acoustic firing system. It’s like Hubba Bubba chewing gum from the 1970s and 1980s.
“We lay it next to the ordnance using a remotely operated vehicle.
“The ROV glides down to the target. The arm manoeuvres and places the charge next to the ordnance.
“We retire a safe distance then use a transmitter to detonate it. We ping a special coded signal to ensure we are reaching the inbuilt battery firing system.”
Mr Welch said it was far safer to conduct these sort of controlled explosions at sea than on land.
He told how after an earlier discovery of a WWII bomb in Portsmouth, buildings containing 2,000 people had to be evacuated.
Mr Welch added: “If a bomb had been on land and exploded, it wouldn’t have knocked buildings over but it would have damaged the structure and broken windows a few hundred metres away.”
The sea disperses energy well – but the firm had to consider the safety and well-being there of seals and dolphins that roam the coast.