Development of a Risk Assessment Framework for Untreated Mine Drainage Discharge Due to Extensive Rainfall in Abandoned Mines

Extensive rainfall can lead to the discharge of untreated mine drainage from abandoned mines. The Ministry of Economy, Trade and Industry aims to promote environmental impact assessments in scenarios where untreated mine drainage discharges may occur due to extensive rainfall. This study aims to develop a risk assessment method for these events, focusing on 26 abandoned mine drainages without responsible parties. We estimated metal concentrations at discharge points under the assumption that untreated drainage is released. A tiered system was used for the risk assessment: Tier 0 evaluates risks using river flow rates during droughts, while Tier 1 uses simulated post-rainfall river flows via AIST-SHANEL.