Pillar recovery adjacent to stabilised rockfill at the Ballarat Gold Project

Remnant rib pillars at Castlemaine Goldfields Ltd.’s Ballarat Gold Project have been sterilised by the placement of loose rockfill in production stopes. The application of selectively injecting low viscosity grout into the backfilled stopes to form a stabilised material has enabled recovery of the previously sterilised pillars. This paper outlines the engineering design, quality control and quality assurance program implemented to ensure the safe and efficient recovery of the rib pillars. The successful program included laboratory testing, numerical exposure stability modelling and in situ monitoring.