Itasca engineers and scientists possess the judgment and necessary experience to effectively and efficiently carry out the application of numerical models.

In the application of numerical modeling, the following factors are integral:

• The conceptual hydrogeologic model on which the numerical model is based must be as representative as possible
• Proper model setup and calibration must be conducted
• Proper boundary conditions must be used
• Proper input parameters must be used
• Appropriate sensitivity analyses must be performed to define the possible range of consequences when important parameters are uncertain or highly variable

Itasca developed MINEDW™, which is a sophisticated, three-dimensional, finite-element groundwater flow program, specifically tailored for mining applications. MINEDW is used worldwide to design dewatering and depressurization systems, predict local and regional environmental impacts of mine dewatering, assist in the design of water-supply systems, simulate the infilling of pit lakes after mining ceases, and estimate pore-pressure distributions within highwalls for geotechnical design purposes. Itasca has also developed a finite-element numerical code for simulating the leaching of gold from heap-leach piles. This code (GHLS) has been used to optimize the design and performance of heap-leach operations. In addition to MINEDW and GHLS, Itasca is well versed and widely experienced in the use of other codes in the analyses of saturated and unsaturated groundwater flow, chemical transport, and surface-water systems.

Current versions of the following public-domain and proprietary codes are maintained and used routinely, depending on the needs of clients and current projects:

• MODFLOW/MODFLOW-SURFACT
• FEFLOW
• HYDRUS
• MT3D99
• PEST
• HST3D
• HEC-1 and HEC-2
• GoldSim

Itasca’s expertise also includes the use of geochemical models to carry out the following tasks: 1) evaluate impacts on the quality of local and regional water resources; 2) predict chemical characteristics of pit lakes; 3) assess the potential development of acid rock drainage and metals leaching; and 4) simulate solution-mining and cavern-development. The codes typically used for these applications include PHREEQC, CE-QUAL, and Geochemist’s Workbench, along with various kinetic models.

• Design and optimization of dewatering systems (both for drainage and depressurization), including evaluation of alternative dewatering systems
• Estimation of dewatering requirements, costs, and inflows to pits and underground workings
• Prediction of dewatering-induced subsidence and the subsidence zone-of-influence surrounding underground and open-pit mines
• Construction and calibration of one-, two-, and three-dimensional numerical flow models
• Simulation of the flow and transport of chemicals
• Predictive simulations of remedial actions and natural attenuation
• Prediction of the positions of phreatic surfaces and pore pressures in highwalls during mining (as inputs to slope stability analyses)
• Simulation of solution mining and cavern development
• Simulation of gold heap-leach operations