Geotechnical monitoring of open pit, Yara Suomi Oy
In summer 2024, Mittausguru Oy implemented a pore water pressure and ground deformation monitoring system for Yara Finland. The objective of the project was to install instrumentation for monitoring the hydrogeological and geotechnical conditions around the Yara Siilinjärvi open pit mine.
Vibrating wire piezometers (VWP) were installed to monitor the pore pressure in the groundwater table surrounding the open pit. In addition, remote monitoring stations were installed for wireless data transfer. The loggers send data to Mittausguru cloudservice, where it can be accessed and analyzed without leaving the office. Automatically updating report view of sensor readings makes it easy to get an overview on the situation. Users can easily set and adjust alarms for any events they want to get informed about immediately.
In addition, time domain reflectometry (TDR) cables were installed, covering the whole drill hole length. TDR cables are a cost-effective alternative to identify when and where deformations are taking place in the bedrock. Sensors were installed into geotechnical drill holes with lengths up to 450 meters. Applied installation type was fully grouted method, where the borehole is fully injected with a selected bentonite-cement grout after the instrumentation. This way it can be ensured that the sensor data corresponds to the actual conditions in the bedrock.
Installation works were executed during May – June 2024 as a joint effort between Mittausguru, Yara and the drilling contractor. Based on the good results, the monitoring system will be expanded in summer 2025.
