At the Motokura mine, mine drainage is treated using a constructed wetland. Although the treatment is usually stable, it may not be able to cope with the rapid increase in mine drainage during snowmelt and rainfall, and further water volume reduction measures are needed. In order to effectively and efficiently implement these water volume reduction measures, a tank model runoff analysis was conducted to clarify the main origin of mine drainage. As a result, it was found that while the volume of mine water is relatively stable, the volume of water exuding from the slag dumping site fluctuates greatly due to the effects of rainfall. Therefore, it is necessary to prioritize countermeasures against the exudate from the slag dumping site.
