Geophysical Approach to
UXO Clearance
At
Sepon20th June 2014
Integrating geophysics, modern technology and up skilling Laos Nationals to increase safety, productivity and the quality of UXO clearance work
Sepon Copper Operation Sepon: 1968 and Today
UXO Clearance at Sepon – 2009
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Turning Point
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Two 250lb MK81 bombs were unexpectedly found in ‘cleared’ areas 4
months apart.
Outside assistance demonstrated that the highly magnetic soils at Sepon
rendered the traditionally used magnetometers ineffective in many areas.
How Were the Bombs Missed?
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‘Mag and Flag’ and Geophysics
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Both methods use exactly the same laws of physics and are often
available in the same detection equipment.
Geophysical surveys record data which is evaluated on a computer.
Therefore, Geophysical surveys are digital while
‘Mag and Flag’ clearance is an analogue method.
Why Use Digital for UXO Clearance?
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• Obtain data which can be analysed, manipulated and
interpreted.
• Reduce the number of false positives.
• Improve quality control of the work.• Provide a record of the UXO clearance work done.
• Increased confidence in the overall quality of the work.
Quality Control Examples
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Digital Record of the UXO Clearance (GIS)
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EM61-MK2A-HP (Geonics)
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EM61-MK2A-HP Data
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EM61 (Modified)
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EM61-MK2A-HP (Modified) - Data
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MK81 at 2.5m
Geophysical Equipment Trials
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Positioning
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Tape measures and prisms DGPS RTK GPS
Improving accuracy
GIS, Field Computers and the Internet
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Bomb Probability Calculator (BPC)
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Used to estimate the expected types, amounts and depth of UXO in a given area.
bomb penetration depth information + U.S. bombing data + statistical analysis = BPC
BPC Sample Views
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UltraTEM: Deep bomb detection(low-latitudes and magnetic areas)
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Up to five 3-componet EM receiver coils
High Powered Transmitter
UltraTEM System (Deep Buried UXO)
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Results of extensive tests at LXML Sepon
• All bombs (MK81 and MK82 under all conditions to at least 3.5 m)
• MK-81 and MK-82 bombs detected at 5 m+ in low-mag conditions
Closing Comments
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• Know what you know
• Know what you don’t know
• No silver bullets
• Develop a toolbox
• Educate
Thank you
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Jason [email protected]
Acknowledgment and Resources: Michael Laneville, Principal Geophysicist
