The Newmont Woodcutters Mine Site is located 80 km south of Darwin, Northern Territory, Australia. Between 1985 and 1998, the Woodcutters mine exploited a large lead-zinc deposit using open pit and underground mining techniques. In 1999, Normandy (the previous owner) initiated decommissioning of the mine, including relocation of all (sulphidic) tailings into the open pit and reflooding of the backfilled open pit. In November 2000, additional studies were commissioned to finalize the closure design for the waste rock and to further evaluate the post-closure impacts on the local groundwater resource.
Newmont (formerly Normandy) Woodcutters Pty Ltd. retained RGC to carry out a detailed hydrogeological investigation and to assist in the development of a closure design for the waste rock pile. A comprehensive drilling and monitoring well installation program was carried out and a groundwater monitoring program (water levels and water quality) was initiated. This field data were used to calibrate a 3D groundwater flow and transport model for the Woodcutters site. This model was then used to predict future recovery of the groundwater levels and to evaluate the impact of pit reflooding and various cover options for the waste rock dump on the local groundwater system.
Newmont Woodcutters Pty Ltd. is currently in negotiations with the local stakeholders to develop closure performance criteria and the eventual release of the site back to the original landowners. The calibrated groundwater flow and transport model will provide an important reference for tracking future closure performance. RGC is currently assisting Newmont Woodcutters Pty. Ltd. in routine monitoring on the site and recalibration of the model, as required.
- Design of ground water monitoring plan.
- Supervision of drilling & monitoring well installation;
- Development & calibration of a 2D seepage model (HYDRUS-2D);
- Development & calibration of a 3D ground water flow model (MODFLOW);
- Prediction of solute transport in aquifer (using MT3D); and
- Assistance in routine monitoring (Reporting, QA/QC)