2.2. Amendment Justifications
2.2.1. Justification for Proposed Amendment 1
Upper Mundic Gully TSF approval will provide a more resilient tailings/water management strategy that
can better accommodate more extreme climatic conditions and further reduce water balance risks. A
water balance modelling assessment has been undertaken to identify risks with the complete report
provided in Appendix G. Approval and operation of the Upper Mundic Gully TSF will provide further
comfort to project stakeholders including the ITE and the DNRMMRRD by further reducing the likelihood
of uncontrolled release events and reducing operational pressures on the Water Treatment Plant
(operated by the DNRMMRRD) that adjoins the OCP.
The precautionary principle has been utlilised when determining the appropriate tailings/water
management strategy. Increasing storage capacity through operation of the Upper Mundic Gully TSF
would provide greater resilience against climatic extremes and reduces potential overtopping risk that
may impact on the receiving environment to ALARP.
As described in Section 2.3.1, there are no other viable locations within the mining tenure to construct
and operate a TSF. A vast majority of the Mount Morgan Mine site is highly disturbed through historical
mining operations. An options assessment in Section 2.3 determined that the Upper Mundic Gully area
is the preferred location for construction and operation of the TSF primarily due to the favourable
topography that allows a valley TSF geometry. Valley TSFs reduce stability risks as they leverage
existing landforms as buttresses whilst limiting seepage of historically placed waste material.
Establishing a TSF in Upper Mundic Gully, to be designed and operated in accordance with tailings
management best practice, is considered a better environmental outcome than the current
environmental setting whereby legacy waste rock can leach uncontrolled to the surrounding
environment. Additionally, positioning the TSF in this location avoids sterilization of resources as the
TSF footprint will occur in an area with no known latent tailings resource recovery.
The Upper Mundic Gully TSF has been designed in accordance with best practice in accordance with
relevant DETSI Guidelines and Australian National Committee on Large Dams (ANCOLD) and provides
additional engineering controls in the form of robust bituminous geomembrane liner to reduce seepage.
The setting within Upper Mundic Gully provides the most favourable location to mitigate potential
environmental harm associated with typical TSF hazards such as overtopping and piping failure. Dam
break and consequence category assessments have been performed and are provided in Section 4.3.2.
Impacts to environmental values have been assessed in Section 2.4 and Section 6 whilst a risk
assessment is presented in Section 7. Assessment outcomes are that this proposed amendment does
not significantly increase the level of environmental harm caused by the relevant activity. Further
justification for the proposed conditions requested as part of this application are provided in Section 2.3
of this report.
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Wulguru Technical Services Pty Ltd – Supporting Information Report
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