Our team completed a detailed hydrogeologic characterization of the carbonate aquifer to delineate its extent, defined the life-of-mine dewatering requirements, and developed the design of the open-pit dewatering operation, while meeting the mine’s water-supply demand and complying with environmental regulations for discharge of excess water.
The dewatering goal was to maintain groundwater levels below the pit floor before mining and throughout the life of the mine. Primary and secondary dewatering strategies were developed to achieve this goal. The primary dewatering strategy focused on reducing groundwater levels with high-capacity vertical pumping wells in permeable zones around the perimeter of the pit to dissipate pore pressure in the pit walls. The secondary dewatering strategy focused on depressurization of lower-permeability zones along the pit perimeter and inside the pit. A combination of active and passive measures, such as vertical in-pit wells and horizontal drains, was used to meet the pit slope design criteria.
