Grasberg Mine, Freeport Indonesia - Regional Groundwater Model Development

PTFI hydrogeologists - Waiting for helicopter
In late 2016, SRK hydrogeologists, Goktug Evin and Vladimir Ugorets, were commissioned by Freeport Indonesia to develop the regional groundwater model for the well-known Grasberg Mine - the world’s largest gold mine and one of the largest copper producers in the world. Besides its enormous dimensions, it poses a real challenge for hydrogeologists due to its complex hydrogeological setting including structurally controlled groundwater flow and high rainfall, up to 5 meters per year. The applied mining method also presents a complication to water management. An approximate 1.5-kilometer-deep open pit is in place and approximately 300 m below the pit bottom, a deeper block cave operation is being constructed. Block caving will propagate to the pit bottom eventually and will create a high conductive zone which connects draw points and the bottom of the open pit. In close proximity to the Grasberg intrusive complex, the East-Ertsberg skarn system has been mined since 1982 by systems of five vertical block caves. The implemented dewatering systems for both areas with a total flow of approximately 41,000 gpm, allow lowered water levels in the vicinity of the open pit and underground mines by discharging groundwater with gravity by a system of upward drainholes drilled from underground drifts. The numerical modeling challenges were handled with the utilization of finite-element MINEDW code. The model was calibrated to the available flow and water level data collected over a 20-year period of active mining and used for predictions dewatering requirements.
 
The team is now working on the pit scale pore pressure modeling and the hydrogeological evaluation of transitioning from open pit into a block cave operation.

Dr. Vladimir Ugorets
Principal Hydrogeologist (SRK Denver)
 
Dr. Vladimir Ugorets, Principal Hydrogeologist, has more than 35 years of professional experience in hydrogeology, developing and implementing groundwater flow and solute-transport models related to mine dewatering, groundwater contamination, and water resource development.  Dr. Ugorets’ areas of expertise are in design and optimization of extraction-injection wellfields, development of conceptual and numerical groundwater flow and solute-transport models, and dewatering optimization for open-pit, underground and ISR mines.
Goktug Evin
Senior Hydrogeologist (SRK Denver)
 
Göktuğ Evin, has 14 years of experience in mining hydrogeology. He specializes in the areas of groundwater flow, aquifer characterization including design and installation of monitoring wells, performing aquifer tests, groundwater and transport modelling both saturated and variably saturated media. He is also experienced in GIS, remote sensing and spatial analyses. He has worked on international projects concerning environmental and feasibility studies related to mine dewatering, water supply and other elements of mine hydrogeology. Mr. Evin has extensive experience in finite element modelling with FEFLOW and MINEDW for pit slope optimization and dewatering studies, including 3D numerical modelling of bench to pit scale depressurization models, design and evaluation of horizontal drain performances, slope pressure monitoring designs and environmental impacts of mine dewatering and pit lake formation after closure.

 

SRK North America