CMT completed geotechnical and hydrogeological supervision of drilling operations

In December 2023, CMT successfully completed geotechnical and hydrogeological supervision of oriented core drilling at the Gross Cluster (Gross deposit) which is being mined by Nordgold gold producer. Supervision was undertaken as part of the additional study program to improve understanding of rock mass geotechnical characteristics and hydrogeological and permafrost conditions.

During the project, CMT logged 2,360 m of oriented core and collected samples to determine mechanical properties of rocks.

As part of hydrogeological studies, packer tests were conducted during borehole drilling using the IPISWIPS system (Australia). Thermistor chains were installed in boreholes to confirm permafrost boundaries. Piezometers were also installed to monitor sub-permafrost aquifer conditions affected by mining operations.

The deposit is predominantly composed of sandstones of varying oxidation degrees. Granites and syenite dikes are present to a lesser extent. Rocks are disturbed by microdefects of varying intensity. The strength of rocks is directly dependent on the intensity of microdefects.

As part of geotechnical studies, the rock mass quality was assessed based on a range of parameters and ratings defined during field investigations. Collected rock samples are tested in the laboratory to determine the rock mechanical properties. Correlation analysis showed good repeatability of the results, which confirms the high quality of works completed.

Hydrogeological field studies provided information on permafrost boundaries, permeability properties and conditions of a sub-permafrost aquifer. The information will enable updating the deposit hydrogeological model and a more accurate estimate of groundwater inflow to the design pit.