M&A characterizes several deep aquifer systems to evaluate the feasibility and potential impacts of proposed block-cave operations at an Arizona mine.
Client: Resolution Copper, a member of the Rio Tinto Group- Time frame: 2001–2010
- Location: Near Superior, Arizona
M&A assessed the potential hydrologic impacts of proposed block-caving operations at the Resolution Mine, one of the largest copper resources ever identified in North America. The investigations — which included extensive characterization efforts and long-term monitoring — were designed to support the prefeasibility study (PFS) and EIS. As part of PFS activities, dewatering of the existing mine workings began in March 2009. Our extensive monitoring activities provided critical information on the system’s response to dewatering activities to be used the EIS process.
As part of our efforts to characterize local and regional hydrogeologic conditions, M&A analyzed available data and designed / initiated a rigorous field exploration program that included:
- Designing and constructing wells to depths of up to 2,000 feet in the Apache Leap Tuff aquifer
- Conducting pumping tests at these wells to quantify aquifer parameters for multiple-completion intervals
- Designing, constructing, and testing exploration wells that were completed within multiple horizons to depths of up to 6,700 feet
- Running long-term tests to quantify the hydraulic properties of aquifers and aquitards
- Instrumenting boreholes with fiber optics and vibrating-wire piezometers, which were grouted in the boreholes at depths of up to 4,500 feet, to monitor rock stresses and pore pressures in units overlying the ore zone
- Installing packers to facilitate the testing and monitoring of multiple water-bearing zones within the ore body
M&A used the data collected during the exploration program to characterize recharge / discharge relationships, integrating all information into a conceptual hydrogeologic model for the groundwater system. Additional drilling and testing is planned for continued hydrogeologic characterization near proposed mining operations.
We developed a preliminary flow model to simulate conditions that will occur when groundwater starts draining to the proposed mine workings — in particular, mine inflow rates and water-level declines in the overlying aquifer. M&A also analyzed the impacts of groundwater inflow during proposed shaft-sinking and tunnel-drilling operations.
M&A designed and implemented a comprehensive program for monitoring groundwater levels and water quality. We also supported permitting for required rights-of-way by conducting analyses and preparing submittals.
M&A installed a real-time monitoring network to track water levels during mine dewatering. Data are uploaded via telemetry to a web portal and accessed as needed by the client.
M&A developed, and maintains, a comprehensive database for the large, multi-parameter chemical data sets generated during ongoing testing and monitoring. Laboratory data are subjected to a rigorous internal QA/QC review before they are digitally uploaded into the project database. Strict protocols are followed for data verification and protection, in accordance with client requirements. The project team has remote access to data and graphical displays via a custom, web-based dashboard we developed. Finally, output from the database can be seamlessly integrated into GIS applications to analyze and display spatial and temporal data.
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