Use of time-lapse 2D and 3D geoelectrical inverse models for monitoring acid mine drainage -a case study

ABSTRACT Coal washing plants produce large amounts of waste, and tailings are generally dumped in piles and impoundments nearby the plants. Sulfide minerals, water infiltration, and oxygen diffusion can result in acid mine drainage (AMD). In this paper, monitoring the AMD generated by a coal washing plant in northeastern Iran was investigated by applying time-lapse 2D and 3D geoelectrical techniques. For this purpose, 2D and 3D geoelectrical surveys with the Dipole-Dipole array were conducted in the area surrounded by an abandoned pile and nearby two impoundments. The surveys were repeated six months after the first measurements to characterize the temporal changes in the medium. 2D geoelectrical time-lapse suggests that the AMD is being generated at the shallower level of the pile. Moreover, the 3D time-lapse and hydrogeochemical analysis indicate that the likely plume is conveyed to the groundwater downstream of the pile. Besides, the results of time-lapse 3D geoelectrical models illustrate that seasonal changes, mainly precipitation, could affect the likely plume and transport it to subsurface layers.