Bombs Away

June 10, 1998

To Clear Explosives From The Seafloor You Have To Find Them First

ROBOT submarines that can sniff out unexploded bombs on the ocean floor may soon be cleaning up live explosives in wartime wrecks, old naval practice grounds and ordnance dumps.

Harbours and beaches throughout the world at the sites of old battles and dis-used firing ranges are riddled with unexploded bombs. Now researchers in California have developed a system that can detect trace amounts of TNT in seafloor sludge.

"If you take a close look, it's kind of frightening," says Murray Derrach, a physicist at the NASA Jet Propulsion Laboratory in Pasadena. "They're right in your back yard."

The US Department of Defense estimates that more than 50 ocean and inland lake sites across the US contain explosive items. For example, several beaches in Florida have been closed since the Second World War when thousands of live shells were dropped in the water during practice landings for the Allied invasion of Normandy.

The military would like to clean up these sites, both to prevent environmental damage from leaking explosives and to raise funds by selling disused bases to commercial bodies. But finding live rounds has been difficult. Many are buried under silt, invisible even to divers. Junk on the site, such as oil drums and lost anchors, can confuse survey vessels searching for live shells with sonar.

John Potter, who runs ordnance cleanup efforts for the US Army Corps of Engineers from Huntsville, Alabama, says only one in a hundred objects that look like bombs from the surface turn out to be live. A system that could identify live shells would save vast amounts of time, he says.

Derrach and his colleagues have now developed a system that detects the chemical signature of explosives.

Author: Jonathan Knight, San Francisco
New Scientist issue 13 June 1998, page 6


New Scientist

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