Mine Rehabilitation Design: Customer Use Case
With the impact of global warming becoming more prominent and widely accepted within Australia, there is a growing expectation that big mining companies must dramatically improve their impact on the environment. The way mining companies rehabilitate the landscape after they have finished mining has become both part of their mining and, more importantly, part of their social license to operate. There are over 150 minefields in Australia, making it the largest in the world.
“I’ve been doing this for 25 years. Global Mapper is my tool of choice and a go-to of the industry.”
For these projects, Brett Rhodes uses Global Mapper Pro to design pre and post-mining rehabilitation surfaces to comply with the most stringent environmental criteria set by the Department of Mineral Resources (DMIRS). The industry term for this type of rehabilitation is “forest-to-forest designs.” These mining pit designs are used to demonstrate to the governing body that an area can be successfully mined and rehabilitated while meeting the strict criteria for erosion, water runoff, reforestation, and more. Rhodes uses Global Mapper through this process from end to end, “It is the perfect software solution to do this.”
Rhodes has been in the mining industry since 1998. He currently holds a Grade 2 Authorised Mine Surveyors Certificate of Competency as well as an Unrestricted Quarry Managers Certificate of Competency with (DMIRS – Department of Mineral Resources). He is also the 2022 Global Mapper Master Award winner.
Landscape Design Requirements
This particular mine in Southwestern Australia is located within a delicate part of the country. As such, any work done in the area must meet some of the strictest environmental criteria in the country. Before extraction can begin, earth models must be created to demonstrate that the work can be done profitably and within the criteria.
Multiple models were created for this project. The first measures the volume of ore to be extracted from the mine. The following designs then demonstrate how the area will be remediated, two of which are loosely outlined in the sections below. These remediations must also meet equipment operation limitations. A depth limitation is imposed because excavators can’t be used below 8 meters. This is modeled in Global Mapper by using custom shaders as heatmaps for elevation. A maximum slope limitation is also applied, as shown below near a modeled pond.
Modeling Ore Extraction
This mine was originally full of abandoned ore. Global Mapper was used to determine how much material needed to be scalped or removed from the top, assuming 1m of material was removed. This step required a volume calculation. The existing elevation was collected via drone flight and generated photogrammetrically in order to create a digital elevation model (DEM). Ore was removed from the model based on elevation, and the difference between the extracted model and the original was measured as volume. With this and other modeling steps, Global Mapper facilitated the design requirements to come up with 100% ore removal, making over $300 million in ore extraction that was otherwise left abandoned.
Creating Ponds to Prevent Erosion
One of the required remediation techniques is the creation of ponds to collect water. These landforms are shaped to disperse water flow, preventing it from funneling toward forested areas. The storage capacity requirement for this area is 960 cubic meters of water. These ponds can’t be too deep and need an average slope of at least 15 overall.
These criteria are easily modeled in Global Mapper. The necessary shape of ponds is first measured by using a simulated water level rise to locate the spillage points and see where the maximum volume of the mined landscape is. The ponds are outlined by creating a contour line at the edge of the pond below the spillage point forming a terrain layer.
After model creation, the watershed analysis tool mapped each of the ponds to determine the catchment area for each pond and region. This step helps to determine if the designed water flow will work as intended. In this case, these ponds have already proven themselves and have been a successful remediation.
Global Mapper has played an integral part in Rhode’s drone flight planning, processing, and data deliverables for mapping analysis. By using watershed analysis tools, gradient shaders, and landform painting tools, these strict landscaping design parameters can be met. These designs are uploaded to machine guidance systems for execution in the field.
Once field execution is completed, Global Mapper checks execution conformance to design. After a very wet winter, these remediation designs proved to be accurately modeled in Global Mapper and performed well. Additionally, these designs saved over $1.7 million in rehabilitation costs.
WORK MADE EASY WITH GLOBAL MAPPER PRO
Global Mapper provides an innovative way for professionals involved in agriculture and other industries to perform a terrain suitability analysis for a variety of use cases. A few freely available data layers were used to identify areas suitable for vineyard development. Of course, not all site selection criteria can be analyzed in a GIS program. Site visits, advanced soil sampling, planning, and infrastructure implementation are all needed before beginning grape cultivation. The areas identified by this suitability analysis are now vector features with attributes describing slope, aspect, area, and soil type that can be further edited, exported, or taken into the field for further site exploration.