Soil Infiltration, Permeability, and Rock Fracturing Assessment to Establish Water Flow Patterns in a Mine with Acid Mine Drainage

Abstract

The flow of acid mine drainage (AMD) and neutral water were assessed inside an underground mine using a volumetric capacity technique, while water infiltration through the ground was assessed by performing three double ring constant load infiltrometer tests. Measured infiltration velocities were slow to moderate, between 0.036 and 2.07 cm/h. Total rainwater infiltration for the sub-basin was 0.031 hm3/yr. Tests performed on representative rock cores of the stratigraphical column of the area indicated that the permeabilities of the altered schist was 4.73E−10 cm/s, the tuff was 1.47E−09, and the graphitic phyllite was 2.47E−06. A structural analysis was performed inside the mine to assess fractures and faults using the mine plans for three different levels. Three major discontinuity paths were identified. Since the ground and rock permeabilities were low, the large water volumes inside the mine were attributed to these fractures. The results of this study are being used to understand flow patterns in the mine and to optimally locate a water treatment system to control the AMD.