Groundwater Flow Simulation in an Open Pit Mine Area for Dewatering Management

Abstract

In an open pit mining, one of the most important problems is the influx of groundwater into the mine. Developing mine below groundwater level is challenging. Poorly controled groundwater dewatering will have negative impacts on the safety, efficiency and economics of mining operations. Knowing the amount and flow direction of groundwater flow into the pit in advance will help reduce the amount of water by proper pumping. From the final pit design based on 2015 design, the maximum approaches are applied for the prediction of the groundwater inflow into the pit when the pit bottom reaches to -90 m level. The simulation of pit dewatering prediction used lake package to simulate pit area of similar lake to store water and simulate the pumping. A groundwater inflow rate is 147.9-231.5 m3/min for maximum rainfall. The dewatering system can install only one set but on wet season the pumping will continue to pump with maximum capacity about 400 hrs. It means that for average rain fall without dewatering, the pump will be operated 1-2 days that the water level will reach to elevation -90 m at the bottom of the pit.