An assessment of hydrogeological properties of waste rock using infiltration tests and numerical simulations

ABSTRACT: Waste rocks are excavated to access the mine orebody and usually disposed of in piles at the surface. The grain size of waste rock from hard rock mines can vary from silt sized particles to large boulders (≥ 1 m). Characterization of their hydrogeological properties is challenging because of their grain size distribution and natural heterogeneity. The flow of water in waste rock piles is mainly controlled by the sandy and gravelly fractions, but the presence of larger particles can create macropores that may influence the hydrogeological characteristics. In this article, the experimental results from a series of infiltration tests conducted on a waste rock pile are analyzed using numerical simulations to assess the local hydrogeological properties of the waste rock from back analyses. The relative influence of the grain size, porosity and water retention capacity on infiltration rates was also evaluated. The article illustrates how this methodology can be used to obtain in-situ hydrogeological properties of waste rock.