Detection of leachate pockets in experimental cell of municipal solid waste with aid of geophysics.

Some geophysical methods have been used to detect and monitor the contamination generated by percolated liquids from industrial and urban waste disposal, being one of them the Electrical Resistivity (ER) method. This method was applied in an experimental cell constructed on a municipal sanitary landfill, located in the city of Campinas, state of São Paulo, Brazil, in order to detect leachate concentration zones within the waste mass. The leachate levels measured within 5 piezometers installed in the experimental cell during the period of 2 ½ years were used to aid the interpretation of the geophysical tests. On the surface of the experimental cell, 6 dipole-dipole profile lines with 5 meters spacing and 10 investigation levels were performed, covering the entire cell area, including piezometers. The results interpreted in some profiles indicated areas with low resistivity (<10 ohm.m), which suggested the presence of leachate concentration zones, close to piezometers with leachate levels at about 1.4m to 2.8m. Where the level of leachate was zero, the interpreted results did not indicate these zones of concentration. In addition, the ER method was able to detect a high resistivity range, below the leachate concentration zones, represented by the high-density polyethylene (HDPE) geomembrane, installed at the base of the cell.