Assignment
Production at the El Valle-Boinas mining site, within the Rio Narcea Gold Belt, had largely been done by open pit methods prior to switching to underground in 2004. The original tailings storage facility (TSF) had also been closed. <

When Orvana Minerals acquired the mine in 2009, the intent was to develop the underground deposit adjacent to the closed pits. To minimise environmental impact, the closed El Valle pit was proposed for permanent storage of the waste (tailings) from the plant processing the ore from the new underground works. Two significant slope failures had already occurred post-closure, along with extensive erosion of the lower slopes. As part of the permitting process, regulators required that the stability of the pit slopes be assessed and remedial measures be implemented to ensure the TSF operates safely.

Our Role
A multidisciplinary Golder team from Spain, UK, France and Ireland have investigated geotechnical and hydrogeological conditions. Their work has resulted in an updated geotechnical model and design assessment to attain the necessary safety factor on the pit walls. The solution was to cut back the slope angle of the pit wall, along with improving the management of surface water and installing discrete slope support measures.