Abstract
Operating open pits are exposed to geotechnical stability risks throughout the life of mine. These risks can be considered part of normal operating conditions and are managed by mining teams. Following the completion of mining, weak rock slopes can exhibit progressive failure mechanisms due to severe erosion or deterioration and are negatively influenced by the post-mining hydrogeological and hydrology conditions. In this context, these failure mechanisms can impact existing or planned mine infrastructure (e.g., water treatment, diversion channels, closure landforms) that is needed to achieve mine closure objectives.
This paper describes key geotechnical and hydrogeological aspects that need consideration in developing a work plan for rigorous mine closure open pit stability assessment in weak rocks. The paper is supported by a case study of a pit stability assessment at the Faro Mine Complex, a former lead-zinc open pit located in Yukon Territory, Canada. For this case study, the importance of the stability assessment work to the positioning of a new permanent non-contact water diversion channel is described, including locating the alignment outside of the predicted long-term pit slope break-back.
Andrew LeRiche
Consultant Rock Mechanics Engineer
