Sea mine (Image: iStock)

CSIRO has developed a sensor to detect undetonated explosives on the sea floor (Image: iStock)

Bombs away: CSIRO finds explosives on seafloor

Over 10 million acres of coastal waters are said to be contaminated by undetonated explosives and our sensor could be the answer to help locate them. (7:40)

  • 23 November 2012

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Glen Paul: G'day, and welcome to CSIROpod, I'm Glen Paul. According to the U.S. Government Agency, the Strategic Environmental Research and Development Program, over ten million acres of coastal waters are contaminated by undetonated explosives.  This isn't, as you might assume, just referring to old naval mines gone adrift. From the end of World War Two until International Treaties were signed in the early 1970s many countries regularly dumped munitions of all types into the sea, and with incomplete records the location of many discarded explosives remains unknown. Typically these explosives rust and corrode at sea, making them even more dangerous.

In an effort to locate these bombs CSIRO has teamed with the Strategic Environmental Research and Development Program and U.S. based research organisation Sky Research, to develop a sensor based on technology normally used to find mineral deposits underground, to detect explosives on the sea floor.

Joining me on the line is CSIRO Electrical Engineer, Doctor Keith Leslie. Firstly, Keith, how did you become involved with the U.S. Government on this project?

Dr. Leslie: Purely by serendipity, Glen. I was in a lift in Salt Lake City at a geophysics conference, and I met a fellow Australian, who was working for a company who was looking at detection of unexploded ordnance, and so we got chatting, and a few years later we actually started to get a project together.

Glen Paul: And which of you made the connection that the sensor could be not only used for finding gold, but for finding bombs?

Dr. Leslie: I guess the person from the U.S. company made that connection, because that was his interest, but once he knew what the capabilities of our sensor system was, he quickly latched onto the fact that we'd be able to assist them find these unexploded ordnance.

Glen Paul: So what makes the detecting device different from others used to normally find bombs?

Dr. Leslie: So what's different about our sensor technology is that it measures gradients of magnetic fields, which allows you to better localise the source of the magnetic anomaly, which is the bomb. Typically this is done using sensors which just tells you that you've got a magnetic anomaly, but our sensor system tells you much more accurately where that anomaly is.

Glen Paul: So that anomaly allows you to separate what is an explosive device, from say a piece of metallic junk?

Dr. Leslie: It's a very difficult problem, because when you're looking for exploded ordnance that you want to deal with, it's often associated with ordnance that has actually exploded, so you've got lots of what's known as scrap. So what you're trying to do, is you're trying to get a picture of the magnetic anomaly to see if it's got symmetry associated with it, and if it's got symmetry associated with it it's probably manmade, and not a piece of scrap. And if it's manmade you want to go and investigate it to see if it's actually an unexploded ordnance and then has to be dealt with.

Glen Paul: So then how do you do that? I understand it's being trialled in the lab, but how will the device be deployed in the ocean?

Dr. Leslie: We're working to depths of about 30 metres, so the whole system will be put on a paravein which will be towed under the water by a powerboat, and there will be electrical connections, and mechanical connections, between the paravein and the boat, and the whole system will be able to be towed at different depths so that we can characterise the magnetic anomalies at different sea levels.

Glen Paul: And you'll take it out of the lab for the next trial?

Dr. Leslie: The next trials we hope to do will be somewhere in the local environment, in the water. We'll make ourselves something that looks like a magnetic anomaly and we'll test it over that. So that'll be our next step.

Glen Paul: And obviously these bombs could do a fair amount of damage to the environment if they were to detonate under water. What else is potentially at risk?

Dr. Leslie: Oh people, because there are a lot of people who do recreational diving, and so they're poking around in areas where they wouldn't normally poke around in, because there are more and more people doing recreational diving, and so they're going to come across this unexploded ordnance. In fact some Pacific islands, they actually make a feature of going out to some of the places where ordnance was dumped after the end of the Second World War, and people go down there and go around looking at all this stuff that's just been dumped, and of course this is now over 60 years old, so some of it's going to be coming pretty thin in its casing and present quite a risk, not only for the environment, but for the people poking around.

Glen Paul: Hmm, it does sound like it could be quite a risky activity. Getting back to its use as an actual mining piece of equipment, could it be used in offshore work, in oil drilling and so on?

Dr. Leslie: Well it could be used for offshore drilling, but the area that we're targeting is on land, where in fact when they're drilling they need to know a lot about the magnetic anomaly to work out where best to put down a drill hole, and again the greater information that we get from our magnetic tensor gradiometer allows us to determine much more accurately where the target is, and so ensure that we drill correctly towards that target, and therefore cutting down the cost of drilling.

Just to give you an example of cost of drilling, I worked up in parts of Canada where there's permafrost, and back in early 2000 it was costing them $700 a metre to do drilling. That just gives you an idea of what costs can be involved if you mistakenly send your drill hole in the wrong direction.

Glen Paul: Hmm, and just getting back to the offshore mining industry, could they use it in its other capacity then for risk mitigation? I mean after all, putting a drill rig down on top of a pile of unexploded ordnance wouldn't be a pretty sight.

Dr. Leslie: Yeah.  When they're looking at drilling in the ocean, I guess they do magnetic anomaly on maps, and basically say, “Oh, there's a lot of clutter here, and so we'll keep away from this area.” No, it's really mainly recreational divers, and just basically a cleanup that they're doing this unexploded ordnance detection for.

Glen Paul: And what about on the land, because we often hear stories of places in the world where there have been wars in the past, and there's all these leftover landmines, and unfortunately people, and particularly children, seem to cop the brunt of some of these mines. Could they also be adapted for use in locating these landmines?

Dr. Leslie: The dreadful thing about landmines is that they're deliberately made to be very hard to detect, and so our detector is dependent on the target having a magnetic signature. And so typically old fashioned landmines – and there's still quite a few of those around – would be encased in metal, which gives us a magnetic signature. But typically the more recent landmines are made of plastic, and they don't have a magnetic signature, and so are much more difficult to detect using our technology, in fact any technology.

Glen Paul: Hmm, I see. So in its capacity for the mining industry, how is its future looking there?

Dr. Leslie: It's definitely got a very promising future in mining. As I was saying in the role of making sure that when you're doing drilling on land that you're drilling towards the target and not away from the target. Which can happen, because a magnetic signature is very hard to interpret, and so the more information you can get about a magnetic signature, the more information you have to ensure that you're drilling towards the target and not away from a target, or the wrong direction towards a target, that's where the big application is we feel in the industry at the moment.

Glen Paul: So when will the sensor become available to the industry?

Dr. Leslie: Well we're aiming to have trials completed at the end of this financial year, and it be available in the next financial year for those that are interested in the geophysics industry, and finding bombs.

Glen Paul: Well, it goes to show what happens when you have a chance meeting with somebody in an elevator, you could end up potentially saving people's lives. Amazing stuff.  Thank you very much for discussing it with us today, Keith.

Dr. Leslie: Thank you, Glen. It was a pleasure.

Glen Paul: Doctor Keith Leslie. And to find out more about the research, or to follow us on other social media, just visit