Tellus environment - Cartographier l'invisible pour agir

Pyrotechnic diagnosis with multisensors in Vannes

Published in Polluted land and soil

  • Client: SID
  • Domaine: Sites & sols pollués
  • Moyens utilisés: magnétomètre/gradiomètre GSM19

Context

The Tellus Environment company has been commissioned by the infrastructure service of the French Ministry of Defence, located in Rennes, for underground inspection of the military ERM of Vannes and pyrotechnic diagnosis. Planners have incidentally discovered a shell landfill, while the historical study did not mention any particular risk. As the site has been occupied and built since 1,5 century, the issue at stake lies in the realisation of a discriminating diagnosis for buried objects, in order to differentiate infrastructure from underground networks and buried ammunition.

Magnetic prospecting as much as low-frequency electromagnetic prospecting (conductivity meter) and high-frequency prospecting (ground-penetrating radar) were conducted owing to the objectives and context of this mission.

 

Methods and equipment

- Scan of the whole zone with the GSM19 proton magnetometer / gradiometer, developed by the GEM Systems company

- Scan of the whole zone with the EM38-MK2 conductivity meter, developed by the Geonics company

- Scan of the whole zone with the MF HIMOD radar, developed by the IDS company: doubt removal on a reduced area, predefined thanks to magnetometry and electromagnetism

- Treatment of the electromagnetic, magnetic and radar data, and drafting of 2D maps

- Magsalia: a reliable 3D decision-support tool, ensuring maximum security in the zone

- Interpretation, identification and marking of the targets on the map

- Classification of depth, forms and materials by coupling the 3 above-mentioned methods

 

Results and customer benefits

Our added value: selecting buried objects

- A more complete discrimination process with 3 prospecting methods and 3D treatment

- Suppression of type I errors

- Depth confirmation by Magsalia process

In a context of major magnetic pollution, Tellus Environment has reduced the UXO risk area from 3 ha to 25 m2.

 

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