Isotope hydrology of the intermontane Elk Valley, British Columbia: an assessment of water resources around coal mining operations

ABSTRACT

This study aimed to synthesise and interpret stable isotopic data (δ²H and δ¹⁸O) from various sources to understand the isotope hydrology around coal mine operations in Elk Valley, B.C., Canada. The data, including precipitation, groundwaters, seeps, and mine rock drains, were used to construct a local meteoric water line (LMWL) for the Elk Valley, evaluate the spatiotemporal isotopic composition of its groundwater, and assess mine seepage and mine rock drain discharge. The study revealed a robust LMWL relation (δ²H = 7.4 ± 0.2 · δ¹⁸O – 4.3 ± 4.1). The groundwater and seep data indicated a winter season bias and a north–south latitudinal gradient, suggesting rapid near-surface groundwater flow without significant post-precipitation evaporation. Porewater isotope samples from unsaturated mine rock piles (MRPs) showed site-specific evaporation patterns, potentially due to convective air flows or exothermic sulphide oxidation. This research revealed the influence of groundwater and meltwater on rock drain discharge. Based on evaporative mass balance calculations, MRPs seasonally contributed ca. 5 %(December base flow) and 22 % (snowmelt) to drain discharge. The findings underscore the value of stable isotope data collections in the Elk Valley to help better define and quantify the hydrology–hydrogeology, including a better understanding of evaporative conditions in MRPs.

KEYWORDS:

• Water isotopes
• isotope hydrology
• Elk Valley
• British Columbia
• deuterium
• oxygen-18
• mining
• coal mining

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was funded by Teck Resources and the Cameco-NSERC Industrial Research Chair to MJH. We acknowledge support from the NSERC-CRD programme to SC. We thank Teck Resources for sharing unpublished isotopic analyses and valuable discussions with employees of Teck Resources, SNC-Lavalin, and SRK (Canada) regarding data interpretation.