Mine dewatering and pore pressure modelling in a complex geologic system

Challenge

A mine water operator needed to improve the reliability of pore pressure estimates for a mine in Peru, as well as optimise the dewatering system with respect to CAPEX and OPEX costs. To address this need, DHI helped our client to develop an advanced groundwater model within the challenging and complex hydrogeologic setting where the mine was situated.

Solution

A high-resolution 4D groundwater flow model for transient pit wall pore pressure and mine inflow estimates was developed for the large open pit mine. The model capitalises on FEFLOW advances, including the application of a fully unstructured mesh that honours the complex geologic model including the explicit incorporation of 56 faults in the pit area. The model, calibrated to historical flow and head measurements, was used to predict pit wall pore pressures through time and identify sectors that will require additional effort to depressurise.

FEFLOW, the all-in-one groundwater modelling solution was used in the project. ©DHI

Results

The hydrological model helped our client:

  • Evaluate pit groundwater inflows and pit wall depressurisation under various pit configurations
  • Numerically optimise a dewatering system using Monte Carlo methods
  • Minimise CAPEX and OPEX costs for dewatering for the life of mine
  • Provide a range of probable pore pressure distributions for slope stability analyses

The project included a dewatering system optimisation based on thousands of model runs to evaluate potential dewatering well locations based on their ability to meet the dewatering objectives in the most cost-effective manner. The analysis considered both CAPEX and OPEX costs and resulted in a wellfield with significantly lower costs than the non-optimised version.

Dewatering system evaluated and optimised

Met all dewatering objectives in the most cost-effective manner

Lowered CAPEX and OPEX costs

About the client

A mine water operator

Software used

FEFLOW

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