Complex Projects. Controlled Delivery
Mines & Tailings
Following updated guidance on tailings dam safety and design, we were commisioned to undertake a detailed geotechnical investigation of ta Tailings Storage Facility in northern Sweden.
Ground conditions presented considerable technical challenges, including up to 20 metres of large rock fill overlying approximately 60 metres of tailings, followed by natural foundation soils and bedrock. GeoSonic were appointed as specialist drilling and testing contractors based on their technical expertise, equipment capability and experience in demanding environments.
The investigation combined sonic, mud rotary and conventional rotary drilling with Standard Penetration Tests, undisturbed sampling, downhole CPT, pressuremeter testing and shear vane testing. Mud rotary drilling was incorporated to establish suitable conditions for liquefaction assessment. Integrating these techniques and their differing sampling requirements onto GeoSonic’s rig required detailed planning to satisfy stringent dam-safety criteria.
Vibrating-wire piezometers and inclinometers were installed in multiple boreholes, providing long-term monitoring of groundwater pressures, ground movement and dam integrity.
Operations continued through Arctic temperatures reaching -30°C. GeoSonic mobilised a complete winterisation system, including an enclosure around the drill platform and mast that maintained an internal working temperature of approximately +15°C for operators and testing teams.
Further complexity arose where the lower dam buttresses extended beneath the clarification pond. The drill rig was mounted on a floating pontoon and frozen into metre-thick surface ice, enabling several investigation positions to be completed safely.
Delivery required extensive coordination between all stakeholders, barge specialists and site crews. Detailed planning and risk assessment addressed ice access, winter survival equipment, rescue procedures, low-ground-pressure transport, pontoon relocation and continuous stability monitoring. This collaborative approach produced high-quality geotechnical information while maintaining rigorous safety standards in an exceptionally challenging environment.
