Gravel Pit Optimisation Using QGIS

Abstract

McMurtrie Consulting Engineers (MCE) has been engaged by North Burnett Regional Council (NBRC) to provide natural disaster event project management services for flood events declared in 2022 and 2024. In response to the disaster, significant quantities of gravel were required all over the region. Prior to the event, NBRC had made the decision to close their Council-managed quarries and burrow pits, citing internal staffing difficulties to comply with mining WHS legislation. The process going forward was to purchase gravel from commercial quarries. Such was the size and scope of the event, that procuring gravel from commercial quarries was not feasible. The cost of cartage and the damage that the unsealed road network would sustain during restoration works would cause more damage than what was being repaired. Two of the commercial quarries were closed due to environmental compliance, and DA non-compliance. This lack of commercial material caused a perfect storm of limited gravel supplies in the NBRC region. MCE ‘s recommendation to NBRC was a strategic opening of gravel pits around the region. These gravel pits would be required to fulfill all Flood Damage related activities, as well as NBRCs maintenance and resheeting projects. The gravel must also fulfill grading requirements for use as an unsealed driving surface. Civil Engineer Rhys Alcorn had developed a tool for his thesis, that calculated the distance from gravel pits to damage locations using QGIS algorithms. This method was retrofitted to determine the closest gravel pit from each damage location on the road network. It was then possible to determine the total gravel required from each gravel location. Furthermore, MCE working in conjunction with NBRC, arranged material testing at each of the proposed gravel pit locations. Optimum gravel sources were identified, with marginal materials excluded from further analysis. Where marginal materials would benefit from material blending, these were considered for further analysis. Excluded gravel pits were removed from the GIS tool, and the calculations were rerun. Total quantities at all viable sites could then be determined. This initiative could be used to develop annual gravel crushing campaigns for local governments. Where damage is known, and resheeting locations are identified, annual crushing requirements can be calculated and advertised for Tender. Furthermore, this tool will allow Councils to determine the shortest path from one location to another location. This could have the following uses: - Determining which damage should be repaired by which work depots. - Closest works depot to any point on road network - Closest water source to damage location - Closest gravel source to damage location If Councils embrace the idea of determining the closest viable resource to works location, significant savings can be achieved in fuel costs, and damage to unsealed road networks. A map showing the closest gravel points for road networks should be hung in every Local Government works department. It is a very powerful tool. This presentation will step the audience through the methodology used to create these outputs.