Geotechnical Design of a Deep Slot Excavation for the Waihi Gold Mine Crusher

A slot of up to 20 m depth was excavated at Waihi Gold Mine as part of an extension to the open pit mining operations. The slot was excavated to house a Stamler crusher and a jaw crusher that would break up ore from the pit for conveying to the extraction plant by conveyor. The subsurface location minimises operational noise. Excavation support was designed incorporating ad hoc inspections of each wall face immediately after each lift was removed. A succinct case history of the work is presented.