Mining Pit Wall Stability

CLIENT: Cobre del Mayo S.A. de C.V.

LOCATION: Alamos, Sonora, Mexico

Cobre del Mayo, a subsidiary operating company of Frontera Copper Corporation, retained BGC to review pit wall stability and to recommend mitigation measures and slope monitoring protocols for the south and northeast walls of the Phase 3 Pit of their Piedras Verdes mine near Alamos, Sonora, Mexico.

BGC initially designed a buttress to stabilize the south wall, and developed appropriate slope movement thresholds to allow safe mining of the northeast wall. The northeast wall was subsequently mined and monitored.

Since that time, BGC has designed pit walls for successive pushbacks and mining phases. A groundwater monitoring program has been implemented to confirm design assumptions for the pushbacks. BGC is also involved in ongoing pit design optimization studies and regular geotechnical reviews of the pit slope performance.