This presentation will address the financial and environmental risks associated with long-term mine closure liabilities. Practitioners frequently face discrepancies between theoretical seepage models and real-world outcomes; this session illuminates how standard laboratory testing flaws, such as sample scalping and omitting hysteresis, artificially inflate water-holding capacity and introduce non-conservative bias into performance predictions.

Drawing on ten-years of empirical field data from Century Mine, the presentation will showcase net percolation rates of 5–9 mm/year under commercial construction conditions, providing highly sought-after, evidence-based benchmarks. This session will also outline a practical, multi-scaled investigative framework that integrates laboratory testing, column trials, and field plots offers engineers, geoscientists, and tailings managers a cost-effective roadmap to satisfy regulatory requirements while ensuring long-term cover performance.