Volumetric Assessment of Leachate from Solid Waste Using 2D and 3D Electrical Resistivity Imaging

This paper presents an approach to estimate volume of leachate from municipal solid waste using 2D and 3D electrical resistivity imaging. This process is a deviation from Water Balance Method (WBM) that is commonly used for leachate quantification at landfill sites. While the WBM emphasis is on generating rate, this geophysical approach estimates the in-situ total quantity of leachate. Five 100m profiles were used to generate five 2D inverted pseudo-sections and a 3D inverted section using RES2DINV and RES3DINV programs respectively. The resistivity of inverted pseudo-sections clearly delineated the contaminant leachate plume (ρ < 5 Ωm), which facilitated its volume estimation. The effective porosity values of clay (0.15) and sand/gravel (0.28) deduced from lithology logs were used in calculating the imaged volume of the leachate. To confirm the measured resistivity variation in the saturated subsurface around the dumpsite, in-situ electrical conductivity values of 1782 μS/cm and 4521 μS/cm were determined for uncontaminated and contaminated zones respectively. A total leachate volume of 2.21 x 103 was estimated for the 1600 survey area.