| Electrical resistivity methods were used to characterize features within the Nacogdoches Landfill in Nacogdoches, Texas. The Geometrics OhmMapper System, a noninvasive capacitively coupled resistivity instrument, was used to collect resistivity data over three landfill cells. Through data processing, 2D images were produced to characterize cell features such as unsaturated versus saturated zones, gas accumulation in void space, low permeability horizons, cell cover system, and contact with cell boundary and bedrock.;Information gathered was useful in determining relative rates of compaction with time, evolution of cell characteristics, and the effects different construction regulations have had on cell development. Although successful in surveying shallow subsurface features, depth of investigation was limited to approximately 6 m; therefore lower portions of cells were not imaged. The results provided gain better insight into stability of cell structure. This method of geophysical surveying can be useful in the 30 year post closure monitoring of cells required by the USEPA by offering a relative low cost and time saving method for landfill characterization. |
