Integrated Geotechnical Stability Assessment and Real-Time Porewater Monitoring of a Tailings Storage Facility in the Rokel-Kasila Belt, Sierra Leone

The long-term geotechnical integrity of Tailings Storage Facilities (TSFs) in tropical environments is a critical challenge for sustainable mining, requiring a transition from static safety assessments to dynamic, data-driven monitoring. This study presents a comprehensive geotechnical evaluation of the TSF at Marampa Mines Limited (MML), situated within the Rokel-Kasila Belt of Sierra Leone. The research integrates three core components: a detailed subsurface investigation using Standard Penetration Tests (SPT) and Cone Penetration Tests (CPTu), numerical slope stability modeling via GEO-5 software, and the implementation of a real-time monitoring network using Vibrating Wire Piezometers (VWPs). Initial field characterization identified the prevalence of "clayey gravel with sand and silty sand" strata, providing the baseline parameters for stability analysis. Numerical results confirmed a robust Factor of Safety (FoS) of 2.08 for the facility’s northern wall. To validate these findings under fluctuating climatic conditions, a network of five VWPs was strategically installed to monitor dynamic porewater pressures. This paper details the rigorous data processing methodologies employed, including temperature and barometric corrections using both linear and second-order polynomial equations. By correlating in-situ shear strength with real-time pressure readings, the study demonstrates how proactive monitoring verifies the operational safety thresholds established during the design phase. This integrated approach provides a replicable framework for the management of critical mining infrastructure in similar tropical geological contexts, ensuring ongoing vigilance and structural integrity throughout the facility’s service life.