surrounding infrastructure are known. Updated DBA/CCA and PMF modelling incorporating the closure spillway will be undertaken at least 6 months prior to cessation of tailings deposition. Existing condition H24 requires submission of a decommissioning plan to the administering authority at least one (1) year prior, to decommissioning any regulated structure specified in the EA. It is appropriate that the submission of this decommissioning plan provide relevant and contemporary technical studies, including PMF assessments. Compliance with existing EA conditions An assessment against the following EA conditions has been undertaken to support this application. ∕ 5.16 W10: The holder of this environmental authority must only undertake mining activities that result in no change to, or a reduction of the effective catchment reporting to the Mount Morgan Open Cut Pit. ∕ W11: The holder of this environmental authority must only undertake mining activities that result in no change to or an improvement in water quality reporting to the Mount Morgan Open Cut Pit. The UMG TSF operational philosophy is that the TSF has been designed with sufficient storage to contain a PMF event and a spillway will not be required during operations. There will be no releases from the UMG TSF to the OCP or any other receiving water body during operations. As such there will be no change to the effective catchment reporting to the OCP, nor any change on the water quality reporting to the OCP. A spillway with capacity to pass the PMF will be required for UMG TSF closure to limit water storage in the longer term. The closure spillway will discharge west towards Turner Creek. As summarised in Section 5.14.1, the water quality of the tailings to be discharged into UMG TSF are alkaline with limited metal concentrations. In the unlikely event that UMG TSF tailings reported to the Open Cut Pit would improve the current acidic water quality of the Open Cut Pit.
Project number: 25B061
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