Performance evaluation of volume measurement methods in mining sites aggregate storage areas

In the mining industry the aggregates sector has an important size in terms of production quantity. Most of the aggregates are produced from natural resources (sand, gravel, crushed rock) in surface quarries. Using traditional ground-based surveying methods to calculate the volume of aggregate stockpiles means a surveyor team must take their equipment on site and capture the coordinates and elevation of multiple points. The points are selected around the base of the stockpile, on top of the stockpile and along the break lines. Once these points have been captured, the surveyor generate surface models. The models are compared against a baseline surface to calculate volume changes. Measuring all the stockpiles in a large stockyard using this method is time consuming and expensive. The surveyor is also exposed to various dangerous conditions (walking near heavy equipment, climbing up unstable stockpile surfaces, etc.). An alternative is using unmanned aerial vehicles (UAV), known as drone, to calculate stockpile volumes. The more points that are captured, the more accurate a surface model will be and a drone can capture more points than a surveyor using traditional methods in a fraction of the time. As an added important benefit, site working operations can continue uninterrupted. The most common question considering using drones for stockpile volume determination is the accuracy of measurements and calculations. In this study, a stockpile made up of gravel aggregate material was measured to compare volume calculations based on data obtained from GNSS point surveys and UAV drone and TLS surveying methods. The obtained results showed that UAV's are suited for fast and safe stockpile volume measurements with an acceptable difference of cubic meters when compared to volume calculation based on surfaces obtained with GNSS measurement points.