Surveying Unstable Ground: Restoring Accuracy in Mine Subsidence

Creating large scale, high precision control networks is one of the most complicated tasks in surveying. Think in-depth mathematical analysis, detailed planning for fieldwork that uses multiple precision technologies and a high attention to detail for the large amounts of data collected. It’s for this kind of work that even other surveyors will turn to Map IQ for assistance.

Subsidence due to underground mining is usually imperceptible, but even the smallest changes in the ground’s position affects the region’s survey marks. These marks are important, yet mostly hidden foundational infrastructure. They’re relied on for accurate positioning in construction, land boundaries and even for determining accurate heights above sea level.

Movement of the control marks across a whole region can create serious problems for future development if left unaddressed. For example, costly construction errors due to infrastructure being built in the wrong place.

Map IQ worked in confidence with a global mining client in the process of decommissioning a longstanding underground mine in a highly populated region. MapIQ’s staff were engaged for reinstatement of provincial survey infrastructure over this region. We were responsible for survey processing, data management, and reporting to the government.

Overview of the combined control network/area of interest. The survey was carried out over 2 years, and integrated a variety of precision survey methods to provide accurate horizontal and vertical control.

Over the three year project lifespan, Map IQ provided reliable direction to involved parties and a novel approach to data management and visualization, allowing transparency regarding works outstanding, and insights gleaned from the processed information.

10 years of deformation monitoring survey compiled and visualised against an overlay of the approximate underground mining extents (magenta linework). Geographically identifying elements removed for confidentiality purposes.

Deliverables provided included a final control network and comprehensive reporting integrating static GNSS, precise levelling, and total station 3d traverse information. Additionally, 10 years of historical monitoring information was compiled, standardised, and presented in a set of plans to facilitate easy interpretation and decision making by non-technical stakeholders.