Abstract:

The Ha Lam Coal Mine, operated by Ha Lam Coal Joint Stock Company – Vinacomin, has been exploited using both open-pit and underground mining methods. After the completion of surface mining, the spoil dumps have been reclaimed and graded to elevations equal to or higher than the regional drainage level. During underground extraction at longwall face 11-1.10 (level −175/−180) in Zone III of Seam 11, located beneath the waste dump of Seam 14 in the western field, a sudden water inrush occurred, disrupting production activities. This study investigates the source of the inflowing water through hydrogeological analysis and field data interpretation. The results reveal a potential hydraulic connection between the overlying spoil dump and the underlying coal seam, which led to the incident. Based on these findings, technical measures are proposed to prevent similar events and to improve the safety and stability of mining operations in the remaining reserves.