How High-Precision Surveying Enabled a Major Mine Upgrade
Client: South Walker Creek (SWC) Mine
Provider: Zeus Project Services
Technology: Trimble® SX12 Scanning Total Station, Trimble® Business Center (TBC)
In March 2023, Peter Firmstone from Zeus Project Services entered discussions with South Walker Creek (SWC) mine to perform high-precision survey and scanning. SWC required highly accurate scan data for a project to upgrade and ‘de-bottleneck’ its processing plant.
During the initial planning stages, Zeus reviewed its inventory of survey instruments. Based on a similar previous project, it was determined that a new solution was required for SWC. While Zeus has extensive experience with various instruments over the years, including Leica, Topcon, and Faro, conventional laser scanners would not meet the project’s specifications. After research, Zeus contacted UPG to discuss the Trimble SX12. Following a successful trial, the decision was made to hire the SX12 to begin the project in mid-2023.
The SX12 is unique in its ability to perform long-range scans without a reduction in scan speed or resolution. This, combined with Trimble Access’ polygon selection and distance selection tools, enabled the team to focus on capturing distant objects, minimise scan times, and filter out foreground obstructions like trees. Furthermore, its high-accuracy prism observations allowed for precise scan registration. Other scanners and scanning total stations were considered; however, they presented unacceptable compromises in either their angular accuracy, resolution, range, or scanning speeds.
As is common with projects of this nature, the scope grew. Early investigations revealed the need to re-establish the original plant control network. To address this, Zeus initiated a long-duration GNSS static survey to serve as the basis for a high-order SX12 traverse, providing millimetre-level control on the current datum. This foundational work involved challenging field conditions, including very hot days, cutting sight lines, and navigating the local wildlife (including snakes and spiders) and other environmental challenges like coal dust, significant slope, and heat shimmer.
As the control network took shape, the scanning work could begin. With the project scope expanding to encompass more infrastructure, Zeus augmented its existing equipment by trialling newer technology like mobile laser scanning. This was particularly useful on critical plant infrastructure that could not be shut down to eliminate vibration. Nevertheless, the SX12 remained a key piece of the puzzle.
External design contractors involved in the project desired the highest achievable accuracies for large area point cloud data, a task complicated by site conditions. Vibration from live plant equipment such as shaker screens, centrifuges, and pumps was prohibitive to on-structure scanning. Inaccessible areas like haul roads and dozer push areas necessitated long-range capture of key structures, where the SX12 proved invaluable. This was especially true for structures subject to vibration or those with too little surface information (like a moving conveyor belt) for a SLAM-based system to register accurately.
For capturing specific areas at long range, the SX12 excelled. It was found to be faster in these situations than dedicated laser scanners due to its higher resolution capabilities, combined with fewer required setups to obtain sufficient coverage at a distance. The field method evolved throughout the project, as Zeus consistently experiments with new methods to improve workflows and maintain the highest achievable precision. This includes testing high-grade laser levels, custom-made elevating tripods, and dedicating time to learning new field and office software.
As fieldwork was completed, attention turned to processing. Zeus investigated new solutions for its software pipeline and acquired Trimble Business Center (TBC) on a subscription model to suit the project’s nature. TBC was used to register and georeference scans from the SX12, categorise point cloud data, and verify the registration accuracy of point clouds from other scanners. The ability of TBC to export open-source formats was a significant advantage. This became particularly important as the project grew, and Zeus needed to register and combine historical and new data from SWC and other contractors—data which was often on arbitrary coordinates.
After network adjustment of the various control inputs, the process involved extensive georeferencing checks on scan data and range and noise cleanup on the point clouds. A key benefit of TBC was its correct handling of scaled and non-scaled data imports from various sources, including different sensor types and both raw and processed data.
Approaching the end of the job in late 2023, Zeus had produced a facility-wide reference dataset. This comprehensive dataset can be used by SWC for any future purpose, not limited to the current upgrade.
Gym for strength training, preparation for carrying the NavVis VLX for 10 hour shifts. The NavVis VLX was supplied by Diverse Surveyors.
This leads to the next phase Zeus will investigate – platforms on which SWC can make the data available to internal or external stakeholders. A range of options is being considered, each with its own pros and cons. At the simpler end, Zeus is looking at Trimble Realworks Viewer, which has an excellent offline point cloud viewing engine. At the more complex end, something like Trimble Connect with Reality Capture extension might suit, this being a more collaborative web-based portal.
Looking to the future, Zeus Project Services is interested to see how man-portable SLAM systems and other products in the total station and scanning space continue to improve. Zeus’s primary focus remains on achieving the highest end of the accuracy spectrum through a combination of rigorous methodology and carefully chosen instruments.
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