Gemson, WJ, Weaver, TR & Heemink, BL 2019, 'Key considerations that can make or break a closure-focused groundwater-monitoring program', in AB Fourie & M Tibbett (eds), Mine Closure 2019: Proceedings of the 13th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 1367-1376, https://doi.org/10.36487/ACG_rep/1915_107_Gemson
(https://papers.acg.uwa.edu.au/p/1915_107_Gemson/)
Abstract: Potential long-term water quality impacts present one of the main challenges for effective closure of mine sites. As such, groundwater-monitoring programs form an inherent part of closure. At many mine sites, groundwater-monitoring programs develop organically over time, in response to specific issues that may arise during the life of the mine. When transitioning from operational to closure-focused groundwater monitoring the programs often undergo greater scrutiny by stakeholders. This transitioning also offers the opportunity to re-evaluate the fundamentals underpinning the program, allowing for the alignment of monitoring efforts with the site and scenario-specific monitoring and closure objectives. If gotten right significant efficiencies can be gained in achieving outcomes that support closure, but if not, quite the opposite.
This paper presents key considerations for a closure-focused groundwater-monitoring program. These include: 1) thorough assessment and confirmation of the constituents of potential concern (COPCs); 2) background concentration thresholds for COPCs that occur naturally (especially important in mineralised areas); 3) the setting of appropriate assessment criteria for water quality monitoring taking into account background concentrations and water uses; 4) developing the program within a source-pathway-receptor framework that clearly considers the environmental setting and potential changes in hydrodynamics following closure; 5) regulatory requirements; and 6) consideration of sampling frequency and temporal trends to develop trigger levels and actions to increase or decrease monitoring effort, to maintain flexibility within the program and to assist with the setting of reasonable end-points.

Keywords: water quality, groundwater, monitoring