Notice
Information request
DNRMMRRD water treatment plant, with the value applied requiring confirmation. b) The evaporators nominate a throughput capacity of 3.35 ML/d. No data is presented supporting this assumption. c) Table 3.1 of the WBM Memo suggests the UGM TSF return water to plant is 7.8 ML/d in Stages 3 and 4. However, clarity is required regarding the purpose of this water transfer and its source (i.e., decant water and/or runoff). d) Table 3.1 also suggests in Stages 3 and 4, the Open Cut Pit (OCP) to UGM TSF transfers is 0.5 ML/d. However, clarity is required regarding the purpose of this water transfer and the simulated rate. Further, this does not appear to align with the operational design aspects of the UGM TSF which states ‘no operational pond level’.
aligns with the proposed operational design aspects of the UGM TSF and the overall best practice management of tailings dams.
9
Water management (UGM TSF)
Provide revised application material which:
It is stated the UGM TSF will provide additional capacity in a potential worst-case scenario should the OCP be at risk of overtopping (GHD, 2025). There is no understanding on the trigger for water transfers to the UGM TSF should the OCP be at risk, nor the potential implications and risks, and the management proposed under the worst-case scenario. The storage of water on tailings dams is not considered best practice and presents a considerable risk, coupled with the reprocessed tailings material containing a 60% liquid content. The UGM TSF Design Report (WSP, 2025) requires clarification as it is stated the water storage requirements assumes ‘no operational pond level’. Given the intentions outlined above, clarification is required regarding this operational objective. Further, there is no discussion on potential drainage requirements with advice stating
a) Detail the trigger to transfer water from the OCP to the UGM TSF and demonstrate all risks to environmental values via a risk assessment can be managed. This must include a description of the water quality from the OCP, the anticipated water volume to be stored on the UGM TSF, the timeframe for its storage and the water content of the reprocessed tailings within the UGM TSF. Provide a robust water management strategy and plan under such event which must demonstrate potential environmental impacts are avoided, mitigated or managed. b) Provide clarification on the ‘no operational pond level’ proposed for the UGM TSF with consideration to the intention to store water on the facility under specific circumstances, the water content of the tailings and the transfer of water from the OCP at 0.5 ML/d. This must include a robust water management strategy including the
Page 8 of 20 • ESR/2016/3447 • Version 4.02 • Last reviewed: 29 OCT 2025
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