EM induction surveys are conducted to:

• Locate buried tanks and pipes
• Locate pits and trenches containing metallic and/or nonmetallic debris
• Delineate landfill boundaries
• Map conductive soil and groundwater contamination
• Characterize subsurface hydrogeology
• Map buried channel deposits
• Map geologic structure
• Conduct groundwater exploration
• Locate conductive fault and fracture zones  

Enviroprobe utilizes the highest quality in EM equipment.  The EM conductivity instrument operates by creating an alternating primary magnetic field in the transmitting coil at an audio-frequency. An electromotive force is produced in buried objects by the primary field.  Due to the high conductivity of these objects, secondary loops of electrical current are created in the subsurface.  This process is known as electromagnetic induction.

The receiving coil responds to an electromotive force generated by the resultant of the primary and secondary fields. The buried objects (e.g. drums, pipelines, etc.) produce characteristic anomalies in the recorded data.  This is due to the addition of the secondary field to the primary.  Electromagnetic methods can map subsurface objects rapidly and accurately. 

This information is also displayed at http://www.gprcentral.com/EM_Induction.html

Lanfill boundries under school property