Combined Geotechnical Investigation on a Tailings Facility

Geomech Africa successfully completed a complex CPTu testing and VWP installation project for the tailings facility at Tronox Fairbreeze Mine in the KZN province in South Africa, delivering exceptional results efficiently, safely, and innovatively. Using CPTu data, engineers from SRK Consulting identified the optimal locations for installing Vibrating Wire Piezometers (VWPs). HQ-size holes were wash-bored at these positions, and Terra Monitoring was subcontracted for the VWP installations.

Project Execution and Innovation
Spanning three months, the project was completed with no incidents or injuries and required minimal manpower. Operations were carried out using a 20-ton CPTu Rig, nicknamed “Bumblebee,” a YWE D90R rotary core drilling machine, and a support truck for water carting. In total, 10 holes were drilled, ranging from 16 to 30.50 metres in depth, and 14 VWPs were installed, with some holes accommodating multiple VWPs at varying depths. The CPTu testing was executed efficiently, yielding excellent data. Several dissipations ran continuously for days, representing the longest such dissipations conducted by GeoGroup to date, which required some problem-solving and innovative approaches.

To optimise costs for the client, multiple probes were run simultaneously, allowing the rig to move between positions while dissipations continued independently. In some cases, dissipations at an original position were maintained by powering the data logger with an inverter connected to alternative power sources, allowing the rig to proceed to another location and gather additional data. This approach enabled continuous data collection, including overnight and over weekends, without interrupting operations. Overall, the original scope gathered 347 metres of CPTu data with 37,460.65 minutes of dissipations.

Additional Scope of Work
As the original scope neared completion, Geomech Africa was commissioned for an additional scope of work, which involved CPTu tests at 21 positions and 8 VWP installations. While this phase emphasised regulatory compliance over extended dissipations, it still produced excellent results. A total of 412 metres of CPTu data was gathered, with 28,989.18 minutes of dissipations, and eight holes were drilled ranging from 6 to 28.50 metres. Some VWPs were installed in alternative locations due to incomplete wall construction at the originally planned positions.

This project highlights Geomech Africa’s ability to deliver complex geotechnical solutions efficiently, safely, and innovatively while providing high-quality data that informed critical engineering decisions. It also underscores the strong collaboration between Geomech Africa, Terra Monitoring, and the various stakeholders, demonstrating what can be achieved when expertise and teamwork come together to achieve exceptional results.