Donlin Gold LLC
CLIENT: Donlin Gold LLC
LOCATION: South-western Alaska, USA
Donlin Gold is proposing the development of an open-pit, hard rock gold mine in south west Alaska. BGC has been retained to gather geotechnical, hydrological, and hydrogeological data to support and undertake the design of the open pit, plan site, waste rock facility, contact and freshwater dams, and the tailings storage facility. BGC’s involvement started in 2003 for Placer Dome by reviewing the existing PFS designs, and continued following the Barrick take-over of Placer Dome in 2006. The feasibility study was completed in 2007 with the most recent update completed in 2011. The project is in the permitting process and our scope currently revolves around supporting the EIS and early stages of dam permitting.
BGC developed a 3D regional-scale groundwater flow model using MODFLOW-SURFACT to support the project from pre-feasibility level studies through to preparation of the Environmental Impact Statement. The model was integrated with a site-wide ExcelTM-based water balance model and both were used to develop a life-cycle water management plan for the project, and evaluate surface water and groundwater interactions throughout the mine life and after mine closure. Feasibility level open pit slope dewatering and depressurization assessments and designs were completed by working closely with the open pit geotechnical group; supported using the regional-scale model in conjunction with a 3D pit-scale cross-sectional model developed in FEFLOW. A large (100’s of kms) 3D regional-scale groundwater flow model was also constructed to respond to supplementary information requests from regulators during the EIS. A 1D HydroGeoSphere model was developed to estimate infiltration and runoff rates for a variety of proposed tailings storage scenarios. Project impacts to the surface water and groundwater flow systems were evaluated.