The Influence of Surface Coal Mining on Hydrology and Solute Transport in the Elk Valley, British Columbia, Canada

English Abstract:

Surface mining of coal in the Elk Valley, British Columbia, involves blasting of overburden rock to access mineable ore. Waste rock is placed in adjacent valleys, where it interacts hydrologically and chemically with the environment. As part of a multi-year R&D program examining the influence of surface mining on hydrological and water quality responses in the Elk Valley, this study investigated the relationship between mining practices, stream flows and solute concentrations. This work focused on the interplay of hydrology, water quality, and mining practice. Concentration-discharge relationships from catchments covered by waste rock show virtually no change of weathering ion concentration with increases in flow. This suggests solute export is transport-limited. Bayesian networks of empirical models were used to calculate annual loads of selenium, a weathering solute, as well as estimate their uncertainty. Load estimates are used to drive a SPAtially Referenced Regression On Watershed attributes (SPARROW) model of selenium, the first known application of SPARROW to a metalloid. The significance of a range of variables associated with waste rock placement techniques were assessed, with most not significantly affecting selenium release rates. Reclaimed area on waste rock spoils was identified as a variable that influenced selenium release rate, with increasing reclaimed area associated with decreasing selenium release. Annual selenium release rates tracked annual runoff, providing evidence that selenium release is largely transport-limited.