Client: Resolution Copper Mining LLC
Location: Pinal County, Arizona, USA
Challenge. Model the impacts of mining on groundwater resources for mine planning and permitting
Solution. Prediction of inflow rates are essential for mine feasibility and provide water balance estimates for use in groundwater impact analyses required for permitting. INTERA is supporting the feasibility-stage evaluation of a proposed copper mine in east-central Arizona. The target zone is a porphyry deposit approximately 7,000 feet below ground surface that will be mined using panel caving techniques. Geologic and hydrogeologic modeling is supporting the feasibility study and the subsequent Environmental Impact Statement (EIS) that will be prepared as part of the overall permitting process. INTERA has developed regional-scale and mine-scale geologic block models using Leapfrog Geo software. Both the regional and mine-scale models were developed as a basis for further groundwater flow modeling in support of mine permitting. Using MODFLOW-SURFACT, INTERA modeled groundwater inflows to two shafts excavated into the graben encompassing the mine. Inflows to the shaft were used to calibrate hydraulic parameters, especially for the deep geologic units. The model will be used to predict inflows to the second shaft as it is deepened, and to predict inflows to additional underground workings as mine development progresses.