IAMGOLD – Open Pit Grounding System Analysis

Project Summary

Our Team conducted advanced soil characterization, grounding system modeling, and fault current distribution analysis to evaluate safety performance and compliance with CSA M421. The scope of work included:

• Conducted soil resistivity testing on site using the Wenner 4-pin method in accordance with IEEE Std 81 to characterize the subsurface soil conditions.
• Inverted the measured soil resistivity data utilizing the CDEGS RESAP module to obtain equivalent multi-layer soils to be utilized in the grounding analysis.
• Create a detailed HIFREQ model of the grounding system including the substation ground grids, distribution lines, transmission lines, building foundations and peripheral ground loops, water pipes, gas pipes, and any buried metallic structures in the vicinity of the grounding system.
• Performed on-site Fall-of-Potential (FOP) testing for validation of the grounding model.
• Simulated the FOP test using the HIFREQ grounding model in conjunction with the detailed multilayer soil model(s) to validate the grounding model. The simulation accounted for the magnetic field induction between test leads and nearby conductive elements such as transmission and distribution line ground return conductors, grounding grid conductors, metallic, and other buried metallic structures. Additionally, conductive coupling effects between the test electrodes, the grounding system, and adjacent conductive structures were incorporated.
• Performed a fault current distribution analysis utilizing the CDEGS FCDIST computation module to determine the fault current split.
• Analysed the performance of the Open Pit grounding system (i.e. step/touch potentials, ground potential rise, transferred potentials.
• Reviewed compliance of the Open Pit grounding system with the requirements of CSA M421 “Use of Electricity in Mines”.
• Provided a specification for a new Open Pit auxiliary ground grid to achieve CSA M421 compliance with respect to transferred potentials.