Monitoring Resistivity in Non-hazardous Waste Landfill Using Time Domain Electromagnetism (Drôme, France)

Geophysical surveys using resistivity methods have been carried out since 2007 at an experimental landfill site (Drôme, France) as a part of ANR French research projects “Bioréacteur” and “Envirhonalp” aiming at optimizing landfill biodegradation of non-hazardous municipal wastes. The objective of the present study is to propose efficient methods to monitor resistivity variations with time using non-destructive and low cost methodology. We experiment an alternative and complementary approach to resistivity (DC) methods using Time Domain Electromagnetism (TDEM). This method is non-destructive, sounds deeply without large extension at the surface, is very sensitive to the conductivity of the ground, and can be used without using electrodes. We present the first results obtained when monitoring resistivity of a cell of 125 000 m3 over one year using time-lapse TDEM. The results are compared to neutron logging and gamma densimetry monitoring. We found that resistivity is not changing with time on this site. A TDEM synthetic modelling is presented to demonstrate the sensitivity of time-lapse TDEM to resistivity changes. Finally, we conclude that TDEM can be an efficient alternative to DC resistivity method for resistivity monitoring related to bio-degradation.