conditions, the methodology to remove latent tailings will be slower than allowed for in the original mine plan. Any delay to removing latent tailings from Sandstone Gully directly impacts construction timeframes for Sandstone Gully TSF, and without a permanent location to discharge tailings the remediation project can not proceed. 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, presented 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 sterilisation of resources as the TSF footprint will occur in an area with no known latent tailings resource. 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 5.2. Impacts to environmental values have been assessed in Section 2.4 and Section 7 whilst a risk assessment is presented in Section 8. 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.
2.2.2
Justification for Proposed Amendment 2
Pipe Corridor The justification for this proposed amendment to update Table A1 of the EA with recent and relevant information pertaining to the Pipe Corridor mine feature alignment. The Pipe Corridor is already an approved feature in the EA, there are no impacts on any environmental values and this proposed amendment does not significantly increase the level of environmental harm caused by
the relevant activity. Surface Exploration
The removal of the exploration mine domain from Table A1 of the EA is justified on the grounds that progressive certification of point feature, that occupy a much larger mine domain polygon, is counterintuitive. Critically, previous drill locations that comprised the surface exploration domain are in fact point features that occur within much larger mine domains. The Mount Morgan Mine site is unique in that exploration has historically been undertaken within the boundaries of mine domains, which is not the case for brownfield site whereby exploration is typically conducted outside of established mine domain boundaries. The requirement to obtain progressive certification for boreholes that are located within larger domains raises concerns around practicality and duplication of the certification process. The definition of mine domain differs across jurisdictions however the precedence set in Queensland under the Progressive Rehabilitation and Closure Plan (PRCP) framework is that rehabilitation areas/improvement areas (which are typically identified through transitioning mine domains/mine
Project number: 25B061
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