Developing a Novel Risk-Based Approach to Tailings Storage Facility Classification and Regulation for Nigerian Conditions

Tailings storage facility (TSF) failures have caused catastrophic loss of life and environmental damage globally, yet Nigeria lacks a fit-for-purpose risk-based TSF classification and regulation system. This dissertation develops an original risk-based TSF classification and regulatory framework specifically calibrated for Nigerian geological, climatic, and institutional conditions. The research combines quantitative risk assessment with regulatory design methodology and is grounded in comprehensive characterisation of 31 active and inactive TSFs across Nigeria's six geopolitical zones. Failure mode and effects analysis was conducted for each TSF, and consequence modelling of potential failure scenarios used dam break hydraulic modelling and population-at-risk mapping. Probabilistic risk assessment integrated failure probability estimates derived from an original Bayesian belief network model incorporating Nigerian-specific data on TSF construction quality, inspection frequency, and extreme rainfall recurrence. The dissertation identifies 12 TSFs warranting immediate heightened regulatory intervention based on the combined probability-consequence risk matrix. An original five-tier classification system is proposed, with differentiated regulatory requirements for each tier including mandatory review frequencies, engineering oversight requirements, and emergency preparedness standards. The regulatory framework is benchmarked against the Mac Arthur Foundation-supported Global Industry Standard on Tailings Management and adapted for the institutional capacity realities of Nigeria's mining regulatory system. Legislative text for incorporation into a revised Minerals and Mining Regulation is drafted as part of the dissertation outputs. Keywords: tailings storage facility, risk-based regulation, Nigeria, dam safety, classification framework.