Three rotary holes were drilled as part of the Molycorp Questa Division Natural Slope Stability Monitoring Program to monitor potential subsidence-induced movement of the mountainside located above the D Orebody block cave. Each hole was instrumented with two types of instrumentation for monitoring potential slope movement: inclinometers/extensometers and time domain reflectometry (TDR) cables. Both instruments measure subsurface deformation and characterize the sliding surface in the event of slope movement. The higher sensitivity of the inclinometers/extensometers is useful for measuring the earliest stages of movement, while the durability of the TDR cables are intended to withstand greater deformation and extend the life of monitoring. AAI was commissioned to design and install the TDR cables, log cuttings for lithology, and install the Slope Indicator inclinometer casing and extensometer rings. All three holes, ranging in depth from 160 to 330 feet, were successfully drilled and instrumented.
