Richardson, DL, Heeley, B, Rissik, D & Iles, M 2022, 'Application of a vulnerability assessment framework to assess environmental risks of solutes at Ranger Mine, Northern Territory, Australia', in AB Fourie, M Tibbett & G Boggs (eds), Mine Closure 2022: 15th International Conference on Mine Closure
, Australian Centre for Geomechanics, Perth, pp. 613-622, https://doi.org/10.36487/ACG_repo/2215_43
Energy Resources of Australia Ltd (ERA) is planning the closure of Ranger Mine. An ecological vulnerability assessment framework (VAF) was applied to water quality modelling results to understand the potential effects of magnesium (Mg) in mine affected waters on aquatic ecosystem values within the mine site. The VAF assessed three elements: (i) understanding contaminant exposure, which was based on water modelling and species/community (ecological component) distributions; (ii) sensitivity of the ecological component to the contaminant, as determined from laboratory ecotoxicity experiments and field-based studies (monitoring, mesocosm experiments), and (iii) the recovery capacity of the ecological component, based on a review of the traits of ecological components. The VAF was applied to four waterbodies – two billabongs and two seasonal creek sites. The VAF identified that at three of the waterbodies, only the most sensitive algae and invertebrates were predicted to be intermittently affected by Mg, but would recover during periods of low Mg. All other ecological components (including other invertebrates, plants, fish and other vertebrates) at these three waterbodies had low vulnerability. Results for the fourth water body indicated that most ecological components were potentially vulnerable to predicted Mg concentrations. The assessment findings for the fourth water body had low confidence due to knowledge gaps regarding the sensitivity of some ecological components, especially aquatic plants on which most species depend. The VAF findings were applied in conjunction with an environmental risk assessment to identify where closure strategies for contaminant management needed review and inform decisions on whether impacts from those strategies would be as low as reasonably achievable (ALARA).
Keywords: aquatic ecosystems, water quality, risk
Bartolo, R, Paulka, S, van Dam, R, Iles, S & Harford, A 2013, Rehabilitation and Closure Ecological Risk Assessment for Ranger Uranium Mine: Documentation of Initial Problem Formulation Activities, internal report 624, Supervising Scientist, Darwin.
BMT 2021, Ranger Mine Closure Water Quality Framework Project – Phase 3 Final Report, BMT, Brisbane, report prepared for Energy Resource Australia.
BMT WBM 2010, Ecological Character Description for Kakadu National Park Ramsar Site, BMT WBM Brisbane, report prepared for the Australian Government Department of Sustainability, Environment, Water, Population and Communities.
Crook, D, Wedd, D, Adair, B, King, A, Mooney, T, Harford, A & Humphrey, C 2021, Fish Migration in Magela Creek and Potential Impacts of Mining-Related Solutes, Charles Darwin University, Darwin.
De Lange, H, Sala, S, Vighi, M & Fabera, JH 2010, ‘Ecological vulnerability in risk assessment – A review and perspectives’, Science of the Total Environment, vol. 408, pp. 3871–3879.
Energy Resources Australia 2021, Water Quality Forecasts – Information for VAF Workshop November 2021, Energy Resources Australia, Darwin.
Humphrey, C & Chandler, L 2018, Use of Field-Effects Information to Inform Surface Water Guideline Values for Magnesium Sulfate in Magela Creek, Supervising Scientist Report 213, Supervising Scientist, Darwin.
Iles, M & Rissik, D 2021, Ranger Closure Aquatic Pathway Receptors Risk Assessment, Energy Resources Australia and BMT report, CDM.03–1114-MR-RAS-00001, version 0, Brisbane.
Iles, M 2019, ‘How can frameworks inform water quality objectives for the closure of the Ranger mine?’, in AB Fourie & M Tibbett (eds), Mine Closure 2019: Proceedings of the 13th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 437-446,
Mooney, TJ, McCullough, CD, Jansen, A, Chandler, L, Douglas, M, Harford, AJ, … & Humphrey, C 2020, ‘Elevated magnesium concentrations altered freshwater assemblage structures in a mesocosm experiment’, Environmental Toxicology and Chemistry, vol. 39, pp. 1973–1987.
Richardson, DL, Bourke, G, Rissik, D, Fisk, GW & Iles, M 2019, ‘Development of a vulnerability assessment framework to evaluate potential effects of mine water discharges from Ranger Uranium Mine, Northern Territory’, in AB Fourie & M Tibbett (eds), Mine Closure 2019: Proceedings of the 13th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 1519-1532,
Turner, K, Tayler, K & Tyrrell, JWR 2015, Revised Ranger Mine Water Quality Objectives for Magela Creek and Gulungul Creek, internal report 638, Supervising Scientist, Darwin.
Weißhuhn, P, Müller, R & Wiggering, H 2018, ‘Ecosystem vulnerability review: proposal of an interdisciplinary ecosystem assessment approach’, Environmental Management, vol. 61, pp. 904–915.