» Equipment
» Environment
» Geophysics
» Archaeology
» Geotechnics
» Hydrogeology
» Geothermics

ENVIRONMENT

Environmental studies concern above all pollution problems, recovery of abandoned quarries, industrial facilities or waste disposal; therefore targets are often buried inorganic and organic waste, metallic waste (debris, tanks, steel drums and unexploded ordnance), contaminating groundwater plumes (leachate and sea-water intrusion).

Locating metallic waste EM61 is very useful, thanks to its good resolution; this is a map of voltage measurements of channel D, regarding UXO detection in the industrial site of Porto Marghera (Venice).

This research was performed together with DAMES & MOORE INTERNATIONAL. Linear yellow anomalies are due to buried metal pipe utilities while circular red anomalies are due to shallow metallic objects as manholes; note the tank on the right side. An unexploded ordnance could be the yellow circular anomaly marked by the arrow.

Also EM31, by in-phase measurement, and proton precession magnetometer, by gradiometer technique, can be used for metallic waste detection. Contaminating plumes can be detected by EM31 or EM47 thanks to their high conductivity.

On the contrary hydrocarbons can assume a resistive behaviour, therefore resistivity methods are preferable. The saline water intrusion into coastal aquifer can be clearly detected by TDEM profiling, thanks to the good contrast among fresh, brackish and saline groundwater.

Therefore it is possible to verify the effect of artificial overexploitation by mapping the geometry of the fresh-saline water interface. The resistivity of saline aquifer is generally less than 1 ohm x m; according to McNeill's equation there is a strict correlation between saline content and rock resistivity.

For this kind of research EM47 transmitter is the most effective instrument, because it is able to detail shallow geological features.