Bas Leezenberg, P, Gkikas, I, Maljaars, H, Bemelmans, M, Andersson, JV, Wahlund, S, Arbuatti, L & Narshai, P 2025, 'Advancing mine closure safety with InSAR: monitoring an inactive tailings storage facility', in S Knutsson, AB Fourie & M Tibbett (eds), Mine Closure 2025: Proceedings of the 18th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 1-9, https://doi.org/10.36487/ACG_repo/2515_19
(https://papers.acg.uwa.edu.au/p/2515_19_Gkikas/)
Abstract: Engineers managing legacy assets such as tailings storage facilities (TSFs) that have been inactive for decades, face many geotechnical challenges such as lack of archived data, uncertainty of past instabilities, remote locations, and inaccessibility. 
We highlight the application of satellite-based interferometric synthetic aperture radar (InSAR) as an effective complementary tool for geotechnical risk assessment after mine closure to proactively manage risk at a TSF that has been inactive for over 30 years. Previous ground-based investigations identified minor, localised zones of subsidence. Consequently, an independent investigation employing InSAR was undertaken to evaluate the presence of any indicators of instability based on patterns of ground deformation.
A five-year period (2019–2024) of SAR images was selected to demonstrate feasibility. Persistent scatterer interferometry (PSI) was used to account for challenging site conditions, including vegetation and water presence. The InSAR specialists optimised a processing methodology to specifically deal with an annual 5month snow season interrupting the continuity of the radar scatterers on the dam. This study demonstrates that this annual gap can be bridged effectively, to generate a high confidence statement about risk-related patterns of motion.
Close collaboration between the owner´s team governing the legacy mine sites, the surveyors and the InSAR specialists ensured the validation of InSAR monitoring results. Combined with the site context, deformation patterns detected were ultimately assessed as non-substantial for overall stability. The partnership between InSAR specialists and site teams was integral to getting meaningful geotechnical insights and supporting decision-making. These important decisions would be more difficult to make without the use of a monitoring system that can retrospectively analyse ground movement.
This practice provides an example of how InSAR monitoring coupled with careful diagnostics and onsite information and validation can act as a catalyst in choosing the right approach to managing geotechnical risk, and is now being expanded in other legacy sites

Keywords: inactive legacy TSF, tailings storage facility, InSAR monitoring, geotechnical risk assessment, mine closure management, snow season data gap, mine closure