A 3D numerical model to assess the performance of the reclamation measures for an abandoned mine site

摘要

Acid mine drainage (AMD) production by mine tailings can be mitigated with a monolayer cover and an elevated water table. This reclamation technique, which aims at using water saturation to limit the diffusion of oxygen, was implemented at the tailings storage facility 2 (TSF 2) of the Manitou abandoned mine site (Quebec, Canada). It was observed through physical modeling of this reclamation technique with the Manitou tailings that a key criterion to stop AMD production is the water table level. A hydrogeological numerical model of the site was built to complement laboratory and field data and assess the reclamation performance according to different scenarios. This paper presents the setup and calibration of the 3D model of the Manitou TSF 2 site. Data was gathered from the 38 ha TSF through geophysical, geospatial, and drilling monitoring. A 3D hydrogeological model was built to perform simulations with a numerical variably-saturated groundwater flow model. The steady-state calibration and determination of the main parameters was achieved by comparing the hydraulic heads to average field measurements. A three year transient state analysis is presented here and compared to hydraulic heads measured at 13 field stations. The results are consistent with the field measurements.