P-PRCP-100905005 · MATERRA METALS LIMITED

Department foundMaximum disturbance footprint discrepancy The proposed PRCP schedule accounts for rehabilitation and improvement of approximately 270.90ha while spatial information illustrates 359.87ha. It is noted that the current version of the EA, effective 1 September 2025, authorises activities across a total of 369.28ha. Section 4.4.1.1 of the PRC planning part describes the remaining 99.21ha of authorised disturbance as undisturbed areas. Although, the PRC planning part nominates a post-mining land use (PMLU) for these areas, Rehabilitation Area (RA) or Improvement Area (IA) as required by the PRCP Guideline have not been provided. Please note that section 126C of the Environmental Protection Act 1994 (the EP Act) requires that all areas disturbed within the relevant mining tenure must be rehabilitated to a post-mining land use (PMLU) or managed as a non-use management area (NUMA). In addition, the PRCP Guideline specify the requirement for the PRC planning part to describe the area of each resource tenure to which the application relates and propose a PMLU (or NUMA) for all land where disturbance has occurred or will occur. As such, a revised PRCP application that includes rehabilitation or improvement of all authorised disturbance is required.

Asked forProvide an updated PRCP application (including proposed PRCP schedule, planning part, reference maps, spatial and appendices) that demonstrates how all land authorised to be disturbed by mining activities will be rehabilitated to a PMLU or NUMA, in accordance with requirements specified in section 126C and 126D of the EP act and section 3 and 4 of the PRCP Guideline. It is noted that the PRC planning part states in section 3.1 that Hidden Treasure (covering ML2784 and ML2492), Ned Kelly (ML90142) and Standby (ML90101) will not be disturbed during any stage of operations. Where there are no planned activities and intent to develop a PRC plan for these areas, the relevant tenures should be considered for surrender from the environmental authority to remove the requirement of a PRC Plan.

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Department foundFinal site design and reference maps The application does not include a final site design and reference map for Hidden Treasure, Ned Kelly and Standby. In addition: • not all authorised disturbance areas (the maximum disturbance footprint) are captured in the provided final site design and reference maps; • flood plain extent layer is not visible in relation to the mining lease on several final site designs.

Asked forProvide updated final site design, reference maps and spatial information for the maximum disturbance footprint and in accordance with section 4.1 of the PRCP Guideline.

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Department foundWater quality: groundwater and surface water The proposed groundwater and surface water monitoring milestone- criteria in RM4 and RM7 does not include reference to the limits or location, nor the source for where this information is provided in the PRC plan. The PRC plan does not identify specific groundwater and surface water monitoring that are representative of post-closure conditions and fit for purpose (i.e., focused on closure rather than operation). Please note that groundwater and surface water limits must be site- specific, and informed by water quality objectives (WQOs), relevant guidelines and background data.

Asked forProvide an updated PRC plan that includes monitoring locations, monitoring frequency, quality characteristics and limits for surface water and groundwater. Provide appropriate site-specific parameters supported by sufficient data in the format specified (refer to Attachment 2). Background data can be used to determine site-specific limits as follows: • For surface water, the 80th percentile of data for upstream/reference sites must be used for phys-chem indicators and the 95th percentile for toxicants. • For groundwater, the 95th percentile of baseline data can be used to determine site-specific limits for all indicators. For further details refer to the DES 2021 Groundwater Guideline: Using monitoring data to assess groundwater quality and potential environmental values.

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Department foundWater quality monitoring (PRCP schedule) The department has determined that additional surface water and groundwater monitoring locations than those identified in the EA are required to adequately capture potential contaminant sources from all disturbed areas. The departments preferred monitoring locations are provided as Table 1 & 2 of this Attachment. In addition, figures identifying the monitoring locations for both surface water and groundwater are required for inclusion in the PRCP schedule.

Asked forProvide a revised PRC plan that includes additional surface water and groundwater monitoring locations as part of a monitoring plan that clearly identify the proposed locations, their rationale, and how they will address potential contaminant risks. Provide figures that identify the monitoring locations for inclusion in the PRCP schedule. Alternatively, review the preferred monitoring locations in Table 1 & 2 of this Attachment and update the proposed surface water and groundwater monitoring requirements with the PRC plan accordingly.

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Department foundFinal void landform: footprint The EA authorises a footprint of 4ha for the Crusader void however, inconsistent footprint for the final void have been identified across the PRCP application. For example, the final void catchment for Crusader void is shown as 8.4ha in Figure 2.4 of Appendix I Crusader Hydrogeological conceptual model by Engeny while spatial information indicates total footprint of 5.12ha. Given, the associated outcome of the void is a NUMA, an increase in the final void footprint must be justified in a manner that the NUMA footprint is minimised in accordance with section 3.3 of the PRCP Guideline. This applies to all nominated NUMAs where the nominated footprint is greater than that authorised in the EA. Further, it is noted that the cumulative footprint for all voids proposed for improvement in the proposed PRCP schedule equate to 53.20ha compared to total authorised footprint of 70.22ha in the EA. A revised PRCP application that provides information for all disturbance authorised in the EA is required to ensure alignment between the EA and the PRCP schedule.

Asked forProvide a revised PRCP application that includes information requirements as specified in section 3.3 of the PRCP Guideline for all proposed NUMAs.

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Department foundLandform Erosion Assessment Appendix K1 provides an erosion assessment for a Waste Rock Dump (WRD) and a heap leach pad at Mount Cuthbert and WRD at Mount Watson, however, it does not provide erosion assessment for landforms at Crusader, Dobbyn, Orphan, Leichhardt, Mighty Atom, Warwick Castle, Hidden Treasure, Borefield, Ned Kelly, Sparklet and Standby sites. In addition, the following require consideration to demonstrate the landforms can achieve stable conditions. • The PRC plan does not provide whole-of-landform performance as recommended in Appendix K. • The report identifies the model was based on soils data obtained for the Rocklands Copper Mine (approximately 90km away) due to absence of site-specific data. However, information to demonstrate material suitability and applicability to Mount Cuthbert and Mount Watson was not provided. • The WEPP erosion model has not been calibrated against observed performance of existing landforms. Sufficient information to demonstrate that that the model parameterisation sufficiently reflects the erodibility properties of the materials present on the waste landforms (both topsoil and underlying material) has not been provided. • Appendix K notes the parameters used do not account for the increased erodibility of sodic and dispersive materials. • The model does not consider future management of the rehabilitation areas where the PMLU is cattle grazing. Appendix K includes specific commentary on the increased risk of erosional instability resulting from grazing. Noting that the proposed PMLU of Low intensity grazing requires management to maintain vegetation and potential to cause increased erosion, it is unclear how the model is considered to demonstrate long- term stability. • Appendix K recommends groundcover level of 60% to maintain erosional stability, however, information to demonstrate this level of vegetative groundcover can be maintained at all times in the long term and options to mitigate risk of reduced groundcover (including redesign of landforms) have not been provided. • The report identifies the limitation of the assessment to an initial view on risk that should inform future detailed assessment and subsequent design phases including site-specific data, material characterisation and validation, expansion to a 3D model (SIBERIA) and detailed design of the final landform. A detailed landform design report to demonstrate stable landforms over a long-term period that considers the recommendations of Appendix K has not been provided. It is unclear how the assumptions, findings, and recommendations of the erosion assessment have been incorporated into the rehabilitation methodology and PRCP schedule. Further information as required by section 3.6.1 of the PRCP Guideline with considerations to model that predicts gully erosion and appropriate erosion mitigation measures and/or milestone criteria to achieve stable landform is required. For further details, refer to available guidance on Final landform design | Queensland Mine Rehabilitation Commissioner.

Asked forProvide a revised PRC plan that includes: A detailed landform design report that demonstrates achievement of stable landforms over a long-term period in accordance with the requirements specified in section 3.6.1 of the PRCP Guideline and incorporates recommendations made in Appendix K. Detailed discussion of the rehabilitation methodology required to achieve the rehabilitation objective, including commentary on how the assumptions, findings, and recommendations of the erosion assessment(s) have been considered and implemented. Appropriate milestone criteria that provide for and demonstrate the achievement of a stable condition, and that are consistent with and informed by the erosion assessment.

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Department foundAppendix E: Mt Cuthbert PRCP Flooding Assessment The flooding assessment report provides flood mapping of 0.1% Annual Exceedance Probability (AEP) and Probable Maximum Flood (PMF) flood events for Mount Watson, Crusader, Mount Cuthbert, Dobbyn, Orphan sites however, flood modelling for sites including Leichhardt, Mighty Atom, Warwick Castle, Hidden Treasure, Borefield, Ned Kelly, Sparklet and Standby sites were not undertaken. Section 5.6 of Appendix E reports that Leichhardt, Mighty Atom, Warwick Castle sites were classified as low-risk sites due to which detailed flood modelling results were not obtained. It is further noted that initial flood modelling were not provided to demonstrate the flood influence at these sites or the low-risk classification. Please note that in absence of a detailed flood modelling including results for the 0.1% AEP and PMF flood events, the interaction of floodwater with the final landform of these sites cannot be determined. In addition, despite section 5.6, section 5.6.2 recommends implementation of rock armour toe protection to minimise the risk of erosion during flood events at Mighty Atom site. It is unclear how this recommendation was determined given detailed flooding assessment at this site was not obtained and an initial flooding assessment to support the recommendation was not provided. Further, Appendix E does not incorporate climate change considerations in flood estimations, as detailed in Australian Rainfall and Runoff 2019 Book 1 (Scope and Philosophy). There is evidence of water ingress into voids at Mount Watson, Crusader, Mount Cuthbert during a 0.1% AEP flood event and Orphan at PMF event, even without factoring in climate change. The issue is expected to worsen under climate change-informed 0.1% AEP and PMF scenarios. Flood models for the 1% AEP event (with climate change considerations) and the PMF event for all sites are required. These models are essential to assess flood risks in line with the PRCP Guideline and to understand the impacts of more frequent (1% and 0.1% AEP) and more extreme (PMF) flood events. In absence of a detailed flood assessment for all sites, including climate change considerations, an assessment to determine whether the final landform achieves a stable condition cannot be undertaken.

Asked forProvide a revised flooding assessment report that includes: • Detailed assessment of flood susceptibility and influence on all final landforms. • An assessment of water ingress into voids, during a 0.1% AEP flood event, including climate change-informed scenarios consistent with the Australian Rainfall and Runoff Guidelines. • Incorporates flood modelling for Leichhardt, Mighty Atom, Warwick Castle, Hidden Treasure, Borefield, Ned Kelly, Sparklet and Standby sites. • Demonstrates that the final landform will achieve stable conditions and not compromise the PMLUs.

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Department foundAppendix E: Mt Cuthbert PRCP Flooding Assessment - Assumptions Appendix E states the following assumptions that require further justification: • No terrain modification has been completed to remove mining features (e.g., access roads, temporary bunding, etc)… site features within the LiDAR survey which have not been overlain by final landform surfaces are assumed to be present post closure and have therefore been included in the models. Clarification is required on whether the features that are not modified for removal will remain in the actual final landform. Where this is not the case, the model must be revised to provide an estimation of flood impacts where structures such as bunds (or those providing flood protection) will actually be removed to ensure the flood risk is adequately captured. This is to ensure that flood behaviour for the final landform is understood and adequate flood mitigation measures are implemented. • No allowance has been made for existing storage inventory within the residual water storages, other than the surfaces picked up in the LiDAR survey. Justification for not including allowance in residual water structures is required as the assumption indicates the flood assessment does not consider how much water these storages may already be holding at the time of the flood event. Further information to clarify this limitation must be provided to interpret the results of the flooding assessment and understand the potential for overtopping.

Asked forProvide justification for the assumptions made in the flood modelling to ensure the flooding risk assessment is representative of the scale of risk expected in the final landform and that the assumptions are appropriate and not compromise the final landform design. Where required, provide a revised flooding assessment that is based on the final landform design and does not include features that are temporary or not form part of the final landform design. Further, include allowance for the water holding structures to consider the capacity of these structures in flood events and/or detailed explanation for not considering allowance to interpret the results of the flood assessment.

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Department foundAppendix J: Void closure plan Section 5 of Appendix J states - the final void WBM water balance model does not account for inflows received from surrounding catchments during flood events. Interaction of the voids with the surrounding catchment from flood events are specifically addressed in the report titled Mt Cuthbert PRCP Flooding Report (Engeny 2023e). As noted in item 8 of this information request, Appendix E does not include adequate information to demonstrate flood influence and interaction with final voids. The water balance for the void does not account for floodwater ingress during extreme flood events (e.g., 0.1% AEP with climate change and PMF). Additionally, there is no evidence provided to demonstrate that the voids can accommodate such inflows without the risk of overtopping. The following observations have been made: • By excluding these inflows, the model does not simulate the full extent of water entering the system during extreme weather or flood scenarios and the volume of water leaving the site and flowing downstream; and • Excluding inflows from surrounding catchments during flood events could result in overtopping, structural failure, or insufficient capacity to manage floodwaters. As such, the water balance model must be updated to include inflows from surrounding catchments, particularly for flood event scenarios including consideration for both ponded water and the accumulation of floodwaters in the void.

Asked forProvide an updated water balance model of the risk of flood ingress and overtopping of the voids rare and extreme flood events (e.g. 0.1% AEP and PMF) including flood-adapted water balances. If applicable; provide a sensitivity analyses to assess the potential impact of external inflows on the site’s water balance and flood risks. Additionally, demonstrate that the voids have adequate capacity to manage these inflows without the risk of overtopping. Include detailed modelling and analysis to substantiate this assessment.

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Department foundResidual voids - Appendix J2; Appendix G3; Appendix I4 and Appendix F5 The PRCP application does not demonstrate that the residual voids, which are proposed NUMAs, will act as groundwater sink in perpetuity. There are conflicting recommendations provided by Engeny across supporting documentation that require further investigation. This includes but is not limited to: • Section 5.1 of Appendix J that states: For the Orphan, Dobbyn and Warwick Castle sites there is no site-specific pre-mining groundwater data. Similarly, there is no groundwater level data for sites where mining has not yet commenced (Mighty Atom and Leichhardt). Due to the uncertainty of these estimates, no definitive conclusion can be drawn regarding whether the final voids at these sites are groundwater sources or sinks. • Section 8 of Appendix G (Dobbyn, Mighty Atom, Orphan, Leichhardt, Warwick Castle) that states: In the absence of site- specific data, taking cognisance of detailed investigations and assessments across the region at larger mine sites, it seems reasonable to assume that the open pits will act as groundwater sinks ...; • Section 6 of Appendix I (Crusader) that states: there is potential for the pit lake to be a source to local groundwaters in the post closure state; • Section 5.1 of Appendix J (Crusader and Mt Watson East) that states: voids may be groundwater sources in the closure state; and • Appendix F that states the pit at Mt Watson will act as sink post closure which conflicts with Appendix J that states Mt Watson voids may act as groundwater source at closure. Appendix J recommends the assumptions to be refined to determine if the residual voids will be a sink or source to groundwater in closure with ongoing monitoring and maintenance of residual voids and local groundwater conditions to confirm residual voids remain a sink. However, this recommendation has not been followed through to determine whether the residual voids will act as sinks in perpetuity.

Asked forProvide an updated hydrogeological assessment and void closure plan for the proposed NUMAs to verify that they function as groundwater ‘sinks’. Where required update the water balance models.

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Department foundAppendix J: Void closure plan - final void water quality The void water quality provided in Appendix J is limited to predicted salinity concentrations. As noted in item 10 of this information request, there is uncertainty on void conditions at closure such that some voids may have potential to be a source to groundwater. As such, it is considered necessary and desirable that metal concentrations for each void be provided to determine the water quality, contaminant of concern, source and pathway over a long-term period. It is further noted that Appendix J also states that: No formal studies have been undertaken to date to determine the potential for stratification or the resulting effect on water quality on the voids. Water quality and stratification is required to assess the water quality and hydrology of the residual voids and long term interaction with the surrounding environment.

Asked forProvide predicted water quality in the long-term period including potential stratification for each void in accordance with section 3.6.3 of the PRCP Guideline. Ensure the modelling predictions are run transiently and over period that reaches equilibrium for water levels and water quality. For further guidance, refer to Technical Papers available at the Officer of the Queensland Mine Rehabilitation Commissioner Modelling residual mine voids | Queensland Mine Rehabilitation Commissioner

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Department foundAppendix M6: Capping methodology review - cover system The cover system proposed in RM4 of the proposed PRCP schedule includes a modified version of cover system from the capping methodology provided in Appendix M Table 5. Further information to confirm that the cover system in RM4 is a landform-specific design is required. In addition, further information to demonstrate that the angle of repose and concave batters have been considered in the landform evolution modelling for each landform and that there’s no risk exposure of encapsulated PAF and ingress of oxygen is required to ensure structural stability of the final landforms.

Asked forProvide information that demonstrates the proposed cover system in RM4 aligns with a landform-specific design in consideration with cover system recommendation in Appendix M. Provide information that demonstrates the cover system layers considered in the landform evolution model will not compromise the waste encapsulated such that the risk of exposure of underneath material is quantified and ingress of oxygen is contemplated.

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Department foundWaste characterisation – section 5.5 of PRC planning part Section 5.5 indicates that waste characterisation information for the Crusader and Mount Watson sites were extrapolated to other sites within the project with site-specific characterisation proposed to occur as part of RM2 of the proposed PRCP schedule. In absence of site-specific waste characterisation for each site, physical behaviour and chemical reactivity of the waste materials is not understood. This is of particular importance where the waste rock material is used to encapsulate highly mineralised waste / PAF or submerged in the voids. For example, it is not reasonably practicable to determine whether the proposal to push Mt Cuthbert WRD into the Mt Cuthbert void (Table 5 of Appendix M) is appropriate in absence of waste characterisation of the material at Mt Cuthbert and modelling to confirm the void will act as a sink in perpetuity (as noted in item 10 of this information request) and not cause environmental harm. Site-specific waste characterisation as specified in section 3.6.1 of the PRCP Guideline is required to understand the physical behaviour and chemical reactivity of the waste material and that rehabilitation milestone-criteria is appropriate and suitable for the PMLUs.

Asked forProvide waste characterisation of overburden material at all sites subject to EA EPML00863313 in accordance with the information requirements in section 3.6.1 of the PRCP Guideline.

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Department foundPMLU: waste rock dump, heap leach pads and ROM areas (RA2 and RA4) The proposed PMLU of Low Intensity Grazing (LIG) aligns with the terminology specified in the EA (the primary the LOD7). However, LIG outcomes are in contrast to the landform design requirements under Schedule F – Table 2 (Landform Design) of the EA. The landform design in Table 2 provides for waste rock dump, heap leach pads and ROM areas slope of 33% - 76% posing a significant restriction for achieving a PMLU of LIG. In addition to the slopes, the identified VII and VIII post- mine land classifications is generally not suitable for cultivation except with careful management. It is noted this is not consistent with the outcome set out in Table 2. Condition F2(d) provides further limitation to successful rehabilitation which must be considered during rehabilitation planning and nominating a PMLU that is sustainable in the long term. F2 All land subject to mining activities must be rehabilitated to: (a) a stable landform and with a self-sustaining vegetation cover and species that are similar to adjoining undisturbed areas; … (d) ensure that the maintenance requirements for rehabilitated land is no greater than that required for the land prior to its disturbance by mining activities; and Further information to demonstrate achievement of the proposed LIG PMLU of structures with consideration to the landform design requirements outlined in Schedule F of the EA is required to ensure a stable and sustainable PMLU can be achieved.

Asked for1. Provide information to demonstrate the proposed LIG on the structures identified in the landform design requirements of the EA are achievable and able to sustain the nominated PMLU in the long term. Provide evidence including outcomes of final landform design requirements outlined in item 6 of this information request to support achievement of PMLU to stable conditions. 2. Pending response to (1) provide a revised PRCP application with alternative PMLU that aligns with the outcomes specified in Schedule F - Table 2. Provide sufficient level of information to demonstrate that the revised PMLU would result in: • all land being rehabilitated to a safe, stable landform with self-sustaining vegetation; • revegetation using native species similar to the surrounding area as proposed in the PMLUP; • consistent PMLU in consultation with the relevant stakeholders.

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Department foundPMLU: all other areas (RA1 and RA3) The application lacks clarity on the assessment criteria for the PMLU nominated in the PRCP schedule. The rehabilitation milestone-criteria and seed mix in Table 33 of the PRC planning part aligns with native vegetation PMLU and provides no consideration to grazing criteria. This is consistent with sections 5.2.3 and 3.1.10, which reflect the seed mix based on pre-mining land use of grazing on native vegetation. As such, clarification on whether the proposed LIG PMLU targets native vegetation or grazing as the predominant use is required to ensure the PRCP schedule includes appropriate milestone-criteria for the relevant use. Additionally, the Post Mine Land Use Plan (PMLUP) which is a subordinate LOD, indicates an intent for cattle grazing on native vegetation, supporting alternative PMLUs such as native vegetation which may support low intensity grazing. Where Mt Cuthbert prefer to adopt fore-mentioned alternative PMLU, sufficient justification to demonstrate the PMLU as substantially similar to LIG and details of Regional Ecosystems (RE) to be established at each site for development of BioCondition benchmarks for the native vegetation must be included in the PRC planning part. However, where the intent of the PMLU is to predominately graze, appropriate grazing criteria and information to demonstrate the following must be provided: • Justification for suitability of proposed seed mix for grazing and addition of 3P (perennial, pasture/productive, palatable) species; • Evidence to demonstrate grazing can be sustained with consideration to the land classification; • Milestone-criteria to achieve land class suitability of 1 – 3.

Asked for1. Clarify the criteria requested for assessment as either grazing or native vegetation with potential for grazing or similar; 2. Where an alternative PMLU is adopted, provide sufficient information to demonstrate the PMLU is substantially similar to LIG grazing having regard to the EA and PMLU and consistent with consultation with relevant stakeholder(s). 3. Pending response to (2), provide a revised PRCP application that includes information requirements specified in adjacent column to support the nominated LIG PMLU.

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Department foundProposed analogue sites RM6 proposes ≥80 % of LFA8 scores from rehabilitated sites exceed LFA results from comparable analogues. However, the PRC planning part does not provide information on the analogue sites, further, refers to native vegetation reference site and transects proposed to occur in future.

Asked forPending response to item 15 of this information request, provide details of analogue sites used as monitoring for rehabilitation success including but not limited to: • Locations (coordinates and maps); • Justification for selected site; • How the site reflects the targeted PMLU characteristics; • Groundcover requirements including species composition of the REs; • Details of how reference sites are monitored; • Weeds and invasive pest species; and • Details of completion criteria. Where applicable, consider if BioCondition framework can be used as an alternative for the proposed analogue sites. It is recommended that BioCondition criteria follow the BioCondition Assessment Manual (V2.2, February 2015, Queensland Herbarium) published by the Office of the Queensland Mine Rehabilitation Commissioner. Provide an updated Rehabilitation Planning Part that includes a monitoring program that considers the recommendations of the Office of the Queensland Mine Rehabilitation Commissioner.

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Department foundGeneral comment Latitude (decimal degree, GDA2020) -19.99428 -19.993 -19.99594 -19.99117 -19.98756 -19.98965 -19.98794 -19.98354 -19.99382 -19.99531 -19.99368 -19.99822 Latitude (decimal degree, GDA2020) -19.98761 -19.99041 -19.7728 -19.76708 -19.77433 -19.76764 -19.77755 -19.77379 -19.77163 -19.81678 -19.82311 -19.817792 -19.819211 -19.820334 -19.821751 -19.82355 -19.821635 Latitude (decimal degree, GDA2020) -19.79822 -19.80042 -20.34295 -20.34278 -20.34528 -19.94027 -19.94475 -19.95213 -19.93462 -19.78747 -19.90595 -19.90425

Asked forLongitude (decimal degree, GDA2020) 139.91659 139.91786 139.9188 139.92091 139.9148 139.9158 139.91975 139.91441 139.92 139.92142 139.91895 139.91871 Longitude (decimal degree, GDA2020) 139.91814 139.91895 139.88141 139.87677 139.89519 139.89828 139.89945 139.89419 139.89799 140.04405 140.04458 140.046623 140.043359 140.043916 140.045273 140.047143 140.050553 Longitude (decimal degree, GDA2020) 139.99974 139.99895 139.93393 139.93683 139.93317 139.99851 139.99143 139.99220 139.99761 140.02538 139.89881 139.89650

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