Coleman Mine, a nickel/copper producing mine for Vale in the Sudbury mining district, is a mature mine that has been in continuous production since 1991. This maturity is reflected in the amount of ore that has been mined from several major ore zones and the number of associated sill pillars, many of which are being mined or are about to be mined. In the main nickel orebody one sill pillar is being mined and two more will start to be mined within the next year. In the main copper orebody three

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... ill pillars are being mined with one more about to be mined. With sill pillars, and other diminishing pillars, there are problems with increased stress conditions that have the potential to lead to major seismic events prior to the complete failure of the pillar. This paper describes the different mitigation strategies that have been put in place at Coleman mine to minimise the risk of major ground instabilities caused by high stress conditions associated with sill pillars.