Use of Electrical Resistivity Tomography in Predicting Groundwater Contamination Due to Non-engineered Landfill

One of the major causes of groundwater contamination in urban areas is the flow of leachate from non-engineered landfills. Use of conventional test wells to predict the contamination is a cumbersome process. In this pilot study, a small-scale landfill having dimensions 4 m × 2.4 m × 0.6 m height was prepared to determine the efficiency of electrical resistivity tomography (ERT) in predicting groundwater contamination due to uncontrolled landfill. ERT survey was performed for five months, and the variations in groundwater contamination were observed. Water samples from the site were analysed for contaminant concentrations. The resistivity of the soil was found to be decreased considerably from around 200 to 20 Ω-m. This low resistivity zone ensured the presence of leachate flow followed by contamination of groundwater. The increased depth of low resistive zone below landfill evidenced the extended depth of groundwater contamination. Charts were prepared by correlating the contaminant concentrations in groundwater with the resistivity values. This chart may help in predicting the groundwater contamination and contaminant concentration using ERT, without making any borehole at a site. The study has evidenced the potential of ERT in predicting groundwater contamination.