Figure 1. Undulating nature of the crest along the west face.W Figure 2. Examples of face profiles for crest blast holes. Blast Design Process Face Profiles From the beginning of the project it was recognized that the larger diameter blastholes coupled with the short and variable bench height would provide an unfavorable blast geometry. The first step to overcome this was to determine the profiles of the free faces around the blast area. UAV flyovers of the blast area were conducted to provide a 3-D representation of the free faces and bench surface. The point cloud produced from this was used to determine the shape of the free faces. Once the shape of the free faces was quantified, it was possible to establish proper placement of the crest holes and develop a custom explosive load for each blasthole. The manner in which the bench would be blasted provided a north free face and a west free face. This quantification of May/June 2022 the free faces was made difficult as loose material had accumulated against the north face when the bench was prepared for drilling. In some areas the loose material covered the lower half of the face. Another issue affecting the creation of reliable face profiles was the undulating crest and toe. Due to a combination of over-break from the historic blast years ago and weathering, the burden at the crest and toe could vary considerably from one hole to the next (figure 1). The west face of the pattern, which was also the face directed towards the closest crusher, had the highest degree of horizontal variation. The vertical variations of the west face were considerable with values of 31 ft (9.4 m) measured between the crest and the toe. In many profiles the minimal 3D burden at the bottom of the hole was upwards at about midheight on the face (figure 2). The Journal of Explosives Engineering 29