2.9 SURFACE WATER DIVERSION. Horse Creek Diversion

Transcription

1 Figure 5.17 TDP Dimensions 2.9 SURFACE WATER DIVERSION Horse Creek, an ephemeral tributary of the Dawson River, passes centrally through MLA and to the east of MLAs and Horse Creek has been identified as a significant surface constraint for mining activities in MLA The Project Stage Plan has been specifically devised to address a short term, temporary, then permanent relocation of Horse Creek. The plan allows for the recovery of coal from underneath the existing Horse Creek, and for the excavated creek diversion to have time to stabilise and develop vegetation prior to being commissioned in order to minimise erosion and sediment runoff. The diversion of Horse Creek will occur in four distinct stages all of which are completed in the first six years of mine operations. The diversion, temporary and final, will be in operation in excess of 25 years prior to mine closure. As a result, ample opportunity is available to monitor the performance of the channel and to make improvements during life of mine, if required. At mine closure the diversion will not require post mining lease maintenance Horse Creek Diversion The diversion of Horse Creek was designed in consideration of the DNRM Draft Manual Works that interfere with water in a watercourse: Watercourse diversions. A comprehensive diversion proposal is documented in Horse Creek Diversion Functional Design Report (Parsons Brinckerhoff 2014) (Appendix L). Elimatta Project

2 The timeframe and diversion sequence of Horse Creek has been driven by the need to; Allow sufficient timing between development and commissioning; Ensure the lowest strip ratio coal is still able to be mined early in the mine life; and, Ensure future mining and dumping operations are not constricted by the location. The key objectives of diverting the Project reach of Horse Creek are as follows: To provide access to the coal resource in a staged manner to suit mine planning timeframe requirements; To provide flood-control to prevent inundation of pits and coal processing or storage areas during flood events; To construct the diversion such that it is self-sustaining and includes existing natural geomorphic, hydraulic, and ecological functions of the creek and surrounding landscape as far as is practically possible given the project constraints. It is important to note that it is unlikely to be feasible to return the system to its pre-disturbance condition; To enhance channel stability using natural methods and reduce long term channel maintenance requirements; and To ensure no liability is imposed on the State, the proponent or the community to maintain the diversion and its associated components. Parsons Brinckerhoff Australia Pty Ltd (PB) was commissioned by Taroom Coal to undertake the detailed design and impact assessment of the Horse Creek diversion. All proposed temporary and permanent diversions are shown in Figure Diversion Stages Stage One involves an initial permanent diversion of the middle segment of Horse Creek with a temporary upstream and downstream link to the existing stream. The initial diversion in natural ground occurs in Year 0, prior to commencement of mining operations, and will be put into use in Year 1. This diversion is outside the pit and dump footprint but within the mining lease. Stage Two involves a temporary diversion across a large meander loop upstream of Stage One to facilitate mining under the final upstream diversion footprint. The Stage Two diversion alignment follows a gently meandering planform through the existing alluvial floodplain, cutting off a significant meander bend in the existing Horse Creek thalweg. The diversion will entail the construction of a low flow channel only, with levees to the west to protect the active pits from flood inundation. Stage Two will be constructed in operational Year 2 of the Project. The Stage Three diversion will be constructed to be operational in Year 4. The diversion will be excavated partially through natural ground, and partially through mine spoil. Stage Three forms part of the final diversion landform, and consists of an engineered floodplain through mine spoil, approximately 200 m wide, containing a meandering low flow channel, as well as a low flow channel constructed through the natural floodplain prior to re-connecting to Horse Creek at the downstream extent of the diversion. Stage Four consists of a final permanent diversion on fill in the south, termed the permanent upstream diversion. It will be constructed in Year 5 of mining operation. It will be put into use in Year 10, thus having this period to stabilise before being opened to full flows. The Elimatta Project

3 complete diversion will have in excess of 15 years until the mine closes to refine the diversion structure to ensure it will be stable post-mining. Stage Four will be constructed to be operational in year 5 of mining operations and will be constructed entirely through mine spoil. This section completes the final landform of the permanent diversion, which by this time incorporates Stage Four, part of Stages One and Three. The Stage Four diversion will comprise an engineered floodplain, approximately 200 m wide, containing a meandering low flow channel, and will incorporate a 100 m wide fill bund between the engineered floodplain and final void location. Elimatta Project

4 Figure 5.18 Horse Creek Diversion Proposal (PB 2014) Elimatta Project

5 2.9.2 Revegetation Growth of grasses, trees and shrubs on banks will be promoted following completion of construction in order to improve stability of the landform and achieve rehabilitation objectives. It is noted that the naturally treed banks of Horse Creek are significantly steeper than the proposed diversion landform with the trees and clayey soils providing natural stability. It is envisaged as part of the natural adjustment process the banks will steepen somewhat and the bed widen. Further details of revegetation of the diversion are provided in Section WATER REQUIREMENTS AND SUPPLY A detailed Site Water Management Strategy (SWMS), developed by JBT Consulting Pty Ltd, will be implemented for the Project pertaining to water usage, supply, storage and management Water Usage Construction Water Usage Water will be required during the construction period of the Project to satisfy the demands associated with the following: Moisture content adjustment for all earthworks associated with the construction of water storage dams, earthworks pads, flood levees, creek diversions etc.; Dust suppression on all cleared construction areas; Potable water for construction staff; and Concrete mixing. Approximately 800 Ml/a will be required during the construction phase of the Project, based on 200 Ml/a for dust suppression, 500 Ml/a for earthworks moisture adjustment, 80 Ml/a for potable water (excluding any allowance for vehicle washing) and nominally 20 Ml/a for concrete mixing. The primary requirement for providing a reliable water supply to the Project, both during the construction and operations periods, is the securing of a reliable external water supply source. Taroom Coal has advised that water will be sourced via an external water supply from a third party commercial water supplier. This will be delivered on a take or pay basis. The external water supply is intended to be pumped into Raw Water Dam 1 (RW1). If the stored water levels in the raw water dam become high enough to risk overtopping, the external water supply can be halted until such time that the dam has sufficient freeboard to prevent overtopping. During the construction period, the external water supply and RW1 will be established as priority infrastructure to provide a reliable water supply Operational Water Usage Potable Water The predicted potable water usage for the Project has been calculated by determining the anticipated water usage associated with the following items: Elimatta Project

6 Consumption by mine staff (including all staff associated with administration, operations, CHPP, trades, capital works, shut down and visitors); Consumption by accommodation village staff; Bath house usage by mine staff; Wash down of heavy and light vehicles; and Wash down of the MIA. The water usage is calculated to vary depending on the mine staging year; although the variation is minor and only affects mine years 1 to 3. The maximum calculated potable water usage in 90 ML/a. CHPP Water Usage The CHPP water usage calculations have been based on a simple water balance through the CHPP to support an average throughput of 7.75 Mtpa ROM, taking into consideration the water contributions from the following component sources: Water input to the CHPP via the ROM coal feed moisture content; Water input to the CHPP via fine tailings return water; Water input the CHPP as make up water to address water deficits; Water output from the CHPP via the product coal moisture content; Water output from the CHPP via the coarse rejects moisture content; Water output from the CHPP via the fine tailings rejects moisture content; and Water losses from the CHPP, arising due to the plant s washing efficiency. Figure 5.19 presents a schematic diagram of the annual water balance calculated for the proposed CHPP. Elimatta Project

7 Figure 5.19 Water Balance Schematic of the CHPP Dust Suppression Water Usage Predicted dust suppression water usage for the operations phase of the Project has been calculated by determining the anticipated water usage associated with the following items: Elimatta Project

8 Dust suppression on the central haul road linking the southern MLA with the northern MLA 50270; Dust suppression on the MIA road leading off the central haul road; Dust suppression on all the pit ramps leading off the central haul road; Dust suppression on all the operational pit floors; and, Dust suppression on the ROM stockpile. The expected variation in water usage is reasonably steady for the Northern MLA 50270, ranging between a minimum of 245 Ml/a in mine year 1 to a maximum of 293 Ml/a between mine years 10 to 30. The expected water usage for the southern MLA is much more variable, ranging between a minimum of 399 Ml/a in mine year 1 to a maximum of 886 Ml/a in mine year 20. This variation is expected, as the mine staging affects the southern MLA more so than it does the northern MLA 50270, due to the movement of pits, pit ramps, spoil dumps and mining equipment as the mine progresses. The SWMS has been prepared assuming that water will be provided to satisfy the dust suppression demands at two locations. A northern water fill point will satisfy the demands from the northern MLA while a southern water fill point will satisfy the demands from the southern MLA Overall Water Usage The overall water usage includes the water demands for the potable supply usage, the CHPP make up water usage and the dust suppression usage. As previously noted, the overall water usage is calculated to vary depending on the mine staging year. This variation in water usage is primarily driven by the expected changes to the extent of surface areas requiring dust suppression. Table 5.9 presents the calculated overall water usage requirements for the operational life of the Project. The maximum water usage volume is calculated to be 3,566 Ml/a. Elimatta Project

9 Table 5.9 Calculated Overall Water Usage Demands for the Project Elimatta Project

10 Water Supply The Project s external water supply will be secured by a connection to the water distribution pipeline network owned by SunWater Limited (SunWater). Supply to the project site will be via a dedicated pipeline alignment adjacent to the WSL railway within the Rail and Services Corridor. Initially, the external water supply will be treated groundwater by-product resulting from dewatering operations associated with CSG extraction. Once construction of the proposed Nathan Dam is complete, the external supply will instead be sourced from Nathan Dam. Details of sourcing the external water supply will be the responsibility of the third party commercial water suppliers engaged by Taroom Coal. Water requirements will be entirely supplied by an external provider and delivered to dam RW1 located in MLA within the MIA. Based on continuing discussions with the water supplier, the external water supply is expected to have a Total Dissolved Solids in the order of 200 mg/l (EC of 300 µs/cm), which corresponds to the background Total Dissolved Solids in a number of surrounding water courses and water storages throughout the Fitzroy Basin area. The external supply water initially sourced from CSG dewatering will be treated by the supplier to a level which provides a maximum Total Dissolved Solids of 200 mg/l. This water quality will be suitable for use in the CHPP and for dust suppression on the mine site. To meet the potable demands, on-site treatment of the supply water will be required to achieve standards for human consumption. Potable water will be treated and monitored to ensure the Australian Drinking Water Guidelines (2011), endorsed by the National Health and Medical Research Council (NHMRC), are satisfied. However, these requirements are likely to be met by smaller filtration systems rather than larger Reverse Osmosis (RO) plants with dedicated waste streams. Detailed design of filter units will be determined as the Project nears development (when water quality details are better understood) WATER STORAGE The Project s SWMS is a sequenced development consistent with the proposed mine staging. The staged development of the SWMS in MLA can be seen in the Mine Stage Plans presented in Section 2.2. The development of the SMWS is summarised in Table An overview of the SWMS for the Project is provided in Figure Details of the controlled release rates and triggers, as per the dam characteristics tables provided in the following sections, are only permitted if they satisfy the Final Model Water Conditions for Coal Mines in the Fitzroy Basin (EHP 2013). Elimatta Project

11 Table 5.10 Summary of Water Management System Changes Over the Mine Life Mine Year SWMS Requirements 1 3 Raw Water Dam RW1 to be constructed External water supply to be constructed North pit and east pit commence operations Environmental Dams EV1, EV2 and EV4 to be constructed Tailings dams TDN and TDNA to be constructed Sediment Dams SD1, SD2 and SD3 to be constructed West pit commences operations Environmental Dam EV3 to be constructed Raw Water Dams RW2 and RW4 to be constructed 5 Raw Water Dam RW3 to be constructed 6 10 Tailings dam TDN reaches capacity and is decommissioned Fine tailings to be pumped to Tailings Dam TDNA Tailings dam TDNA reaches capacity and is decommissioned North pit ceases mining operations Fine tailings to be pumped to TDP Environmental Dam EV1 is decommissioned 20 Raw Water Dam RW3 is decommissioned 30 Raw Water Dam RW2 is decommissioned Raw Water Dam RW4 is decommissioned NB. The SWMS assumes the TSFs will be used in sequence (opposed to cycled, as proposed) so as to account for the lowest rate of water return from supernatant water back to the CHPP. This is considered the worst case scenario. Elimatta Project

12 Figure 5.20 Schematic of the Site Water Management System Elimatta Project

13 Mine Pit - E1 Mine Pit E1 is located in the north eastern portion of MLA The capacity of the pit floor sump in Pit E1 is 40 Ml and the pump dewatering rate for this sump is 200 Litres per second (L/s) for all mine staging years. At mine year 30, Pit E1 and Pit E2 join to become a final void located in the south east corner of MLA This transition is represented in the SWMS by retaining Pit E1, whereas Pit E2 becomes nonfunctional at mine year 30. The void characteristics of Mine Pit E1 are summarised in Table Review of the model simulations undertaken as part of the development of the SWMS indicate that this pit did not overflow in any of the modelled climate simulations. Dewatering flows will report to the Environmental Dam EV2. Mine Staging Year Table 5.11 Void Characteristics of Mine Pit E1 Pit Capacity (Ml) Floor Sump Capacity (Ml) Dewatering Rate (L/s) Dewatering Destination Env. Dam EV Env. Dam EV Env. Dam EV Env. Dam EV Env. Dam EV Env. Dam EV Env. Dam EV Env. Dam EV Env. Dam EV2 Mine Pit - E2 Mine Pit E2 is located in the south eastern portion of MLA The capacity of the pit floor sump in Pit E2 is 50 Ml and the pump dewatering rate for this sump is 200 L/s for all mine staging years prior to year 30. At year 30, Pit E1 and Pit E2 join to become a final void located in the south east corner of MLA As previously detailed, this transition is represented in the SWMS by retaining Pit E1, whereas Pit E2 becomes non-functional at mine year 30. The void characteristics of Mine Pit E2 are summarised in Table Review of the model simulations undertaken as part of the development of the SWMS indicate that this pit did not overflow in any of the modelled climate simulations. Dewatering flows will report to the Environmental Dam EV2. Elimatta Project

14 Mine Staging Year Table 5.12 Void Characteristics Mine Pit E2 Pit Capacity (Ml) Floor Sump Capacity (Ml) Dewatering Rate (L/s) Dewatering Destination Env. Dam EV Env. Dam EV Env. Dam EV Env. Dam EV Env. Dam EV Env. Dam EV Env. Dam EV Env. Dam EV Env. Dam EV2 Mine Pit - N Mine Pit N is located in the northern portion of MLA The capacity of the pit floor sump in Pit N is 20 Ml and the pump dewatering rate for this sump is 200 L/s for all mine staging years up to year 10. After mine year 10, Pit N ceases to be an operational pit and it transitions to an in-pit TSF named Tailings Dam Pit (TDP). This transition is represented in the SWMS by TDP, which becomes functional after mine year 10, while Pit N becomes non-functional after mine year 10. The void characteristics of Mine Pit N are summarised in Table Review of the model simulations undertaken as part of the development of the SWMS indicate that this pit did not overflow in any of the modelled climate simulations. Dewatering flows will report to the Environmental Dam EV1. Mine Staging Year Table 5.13 Void Characteristics Mine Pit N Pit Capacity (Ml) Floor Sump Capacity (Ml) Dewatering Rate (L/s) Dewatering Destination Env. Dam EV Env. Dam EV Env. Dam EV Env. Dam EV Env. Dam EV n/a Elimatta Project

15 Mine Staging Year Pit Capacity (Ml) Floor Sump Capacity (Ml) Dewatering Rate (L/s) Dewatering Destination n/a n/a n/a Mine Pit - W Mine Pit W is located in the south western portion of MLA The capacity of the pit floor sump in Pit W is 30 Ml and the pump dewatering rate for this sump is 200 L/s for all mine staging years after mine year 1, as this pit does not exist at mine year 1. The void characteristics of Mine Pit W are summarised in Table Review of the model simulations undertaken as part of the development of the SWMS indicate that this pit did not overflow in any of the modelled climate simulations. Dewatering flows will report to the Environmental Dam EV3. Mine Staging Year Table 5.14 Void Characteristics Mine Pit W Pit Capacity (Ml) Floor Sump Capacity (Ml) Dewatering Rate (L/s) Dewatering Destination n/a Env. Dam EV Env. Dam EV Env. Dam EV Env. Dam EV Env. Dam EV Env. Dam EV Env. Dam EV Env. Dam EV3 Environmental Dam - EV1 Environmental Dam EV1 is located in the northern portion of MLA near to Pit N. Due to the predicted high salinity (median Total Dissolved Solids 3,700 mg/l) of the water stored in the dam, this dam will be classified with a significant hazard category in accordance with the Manual for Assessing Hazard Categories and Hydraulic Performance of Dams (DERM 2012). The capacity of Environmental Dam EV1 is 50 Ml for the initial mine staging. After mine year 10, Pit N will cease to be an operational pit and it will transition to become the TDP. Environmental Dam EV1 Elimatta Project

16 will be decommissioned at that time. Controlled flow releases and uncontrolled overflows from this dam will be directed to the Horse Creek receiving waters. However, the prioritised pumping order for this dam will be as follows: Priority 1 Destination: South water fill point demand Priority 2 Destination: Controlled release to Horse Creek The characteristics of Environmental Dam EV1 are summarised in Table Table 5.15 Dam Characteristics EV1 Mine Staging Year Dam Capacity (Ml) Transfer Pumping Rate (L/s) Transfer Pumping Destination South Water Fill Point WFPS1 Controlled Release Rate (L/s) Controlled Release Trigger Volume (%) n/a 0 0 Environmental Dam EV2 Environmental Dam EV2 is located in the north eastern portion of MLA near to Pit E1. Due to the predicted high salinity (median Total Dissolved Solids 5,605 mg/l) of the water stored in the dam, this dam will be classified with a significant hazard category in accordance with the Manual for Assessing Hazard Categories and Hydraulic Performance of Dams (DERM 2012). The capacity of Environmental Dam EV2 is 400 Ml for all mine staging years. Controlled flow releases and uncontrolled overflows from this dam will be directed to the Horse Creek receiving waters. However, the prioritised pumping order for this dam will be as follows: Priority 1 Destination: South water fill point demand Priority 2 Destination: Controlled release to Horse Creek The characteristics of Environmental Dam EV2 are summarised in Table Table 5.16 Dam Characteristics EV2 Mine Staging Year Dam Capacity (Ml) Transfer Pumping Rate (L/s) Transfer Pumping Destination South Water Fill Point (WFPS1) Controlled Release Rate (L/s) Controlled Release Trigger Volume (%) Elimatta Project

17 Environmental Dam - EV3 Environmental Dam EV3 is located in the south western portion of MLA near to Pit W1. Due to the predicted high salinity (median Total Dissolved Solids 4,767 mg/l) of the water stored in the dam, this dam will be classified with a significant hazard category in accordance with the Manual for Assessing Hazard Categories and Hydraulic Performance of Dams (DERM 2012). The capacity of Environmental Dam EV3 is 100 Ml for all mine staging years at mine year 3. Controlled flow releases and uncontrolled overflows from this dam will be directed to the Horse Creek receiving waters. However, the prioritised pumping order for this dam will be as follows: Priority 1 Destination: South water fill point demand Priority 2 Destination: Controlled release to Horse Creek The characteristic of Environmental Dam EV3 are summarised in Table Table 5.17 Dam Characteristics EV3 Mine Staging Year Dam Capacity (Ml) Transfer Pumping Rate (L/s) Transfer Pumping Destination Controlled Release Rate (L/s) Controlled Release Trigger Volume (%) n/a South Water Fill Point (WFPS1) Environmental Dam - EV4 Environmental Dam EV4 in the SWMS actually represents 5 smaller, linked dams located in the vicinity of the MIA in the southern portion of MLA These smaller dams include the stockpile west dam, the stockpile east dam, the MIA dam, the TLO dam and the CHPP dam. These environmental dams will receive contaminated runoff from the MIA catchments. Due to the predicted high salinity (median Total Dissolved Solids 3,964 mg/l) of the water stored, these dams will be classified with a significant hazard category in accordance with the Manual for Assessing Hazard Categories and Hydraulic Performance of Dams (DERM 2012). The combined capacities of the dams which form Environmental Dam EV4 are 380 Ml for all mine staging years. These dams have been represented as a single storage dam in the SWMS. Controlled flow releases and uncontrolled overflows from this dam will be directed to the Horse Creek receiving waters. However, the prioritised pumping order for this dam will be as follows: Priority 1 Destination: CHPP water demand Priority 2 Destination: North water fill point demand Elimatta Project

18 Priority 3 Destination: Controlled release to Horse Creek The combined characteristics of the dams which form Environmental Dam EV4 are summarised in Table Table 5.18 Dam Characteristics EV4 Mine Staging Year Dam Capacity (Ml) Transfer Pumping Rate (L/s) Transfer Pumping Destination North Water Fill Point (WFPN1) Controlled Release Rate (L/s) Controlled Release Trigger Volume (%) Tailings Dam TDN Tailings Dam North (Dam TDN) is located in the mid portion of MLA 50270, west of the MIA. Due to the predicted high salinity (median Total Dissolved Solids 2,504 mg/l) of the water stored in the dam, this dam will be classified with a significant hazard category in accordance with the Manual for Assessing Hazard Categories and Hydraulic Performance of Dams (DERM 2012). The capacity of the Dam TDN starts at 13,060 Ml in mine year 1, but then progressively reduces due to filling with fine tailings. At mine year 5, the capacity of the dam is reduced to 3340 Ml and from that time on, fine tailings are no longer directed to this storage. The fine tailings are instead directed to the Dam TDNA. The gradual reduction in the capacity of Dam TDN has been accounted for in the SWMS. Emergency releases from this dam will be directed to the Horse Creek receiving waters. However, the prioritised pumping order for this dam will be as follows: Priority 1 Destination: CHPP water demand Priority 2 Destination: North water fill point demand Priority 3 Destination: South water fill point demand Priority 4 Destination: Controlled release to Horse Creek Dam TDN is planned to receive fine tailings between mine years 1 and 6, at which stage this tailings dam will have reached its capacity. A depth of at least 3 m will be left between the final tailings surface and the dam s crest level, to facilitate the capping and stabilisation of the captured tailings, prior to the end of mining. In the meantime, this 3 m depth will still be available for the capture of local catchment runoff in the dam. Cycling tailings disposal between TDN and TDNA is considered a viable alternative to improve fine rejects consolidation and extend the life of the surface TSFs. The scenario modelled in the SWMS is the worst case disposal method to model storage behaviour. Under a cycling disposal strategy, Dam TDN would reach capacity after nine years. The characteristics of Dam TDN are summarised in Table Elimatta Project

19 Table 5.19 Dam Characteristics TDN Mine Staging Year Dam Capacity (Ml) Transfer Pumping Rate (L/s) Transfer Pumping Destination 100 CHPP North Water Fill Point (WFPN1) South Water Fill Point (WFPS1) 100 CHPP Controlled Release Rate (L/s) Controlled Release Trigger Volume (%) North Water Fill Point (WFPN1) South Water Fill Point (WFPS1) Tailings Dam TDNA Tailings Dam North Alternative (Dam TDNA) is located in the northern portion of MLA Due to the predicted high salinity (median Total Dissolved Solids 2,504 mg/l) of the water stored in the dam, this dam will be classified with a significant hazard category in accordance with the Manual for Assessing Hazard Categories and Hydraulic Performance of Dams (DERM 2012). The capacity of the Dam TDNA starts at 11,770 Ml in mine year 1. Dam TDNA is planned to receive fine tailings between years 6 and 10, after Dam TDN has reached capacity. At mine year 10, the capacity of the dam is reduced to 2,450 Ml and from that time on, fine tailings are no longer directed to this storage. The fine tailings are instead directed to TDP. The gradual reduction in the capacity of Dam TDN has been accounted for in the SWMS. Emergency releases from this dam will be directed to the Horse Creek receiving waters. However, the prioritised pumping order for this dam will be as follows: Priority 1 Destination: CHPP water demand Priority 2 Destination: North water fill point demand Priority 3 Destination: South water fill point demand Priority 4 Destination: Controlled release to Horse Creek A depth of at least 3 m will be left between the final tailings surface and the dam s crest level, to facilitate the capping and stabilisation of the captured tailings, prior to the end of mining. In the meantime, this 3 m depth will still be available for the capture of local catchment runoff in the dam. Elimatta Project

20 Cycling tailings disposal between TDN and TDNA is considered a viable alternative to improve fine rejects consolidation and extend the life of the surface TSFs. The scenario modelled in the SWMS is the worst case disposal method to model storage behaviour. Under a cycling disposal strategy, Dam TDNA would reach capacity after 16.7 years. The characteristics of Dam TDNA are summarised in Table 5.20 Table 5.20 Dam Characteristics TDNA Mine Staging Year Dam Capacity (Ml) ,770 Transfer Pumping Rate (L/s) Transfer Pumping Destination 100 CHPP North Water Fill Point (WFPN1) South Water Fill Point (WFPS1) 100 CHPP Controlled Release Rate (L/s) Controlled Release Trigger Volume (%) , North Water Fill Point (WFPN1) South Water Fill Point (WFPS1) Tailings Dam Pit (TDP) (In-pit TSF) As previously described Pit N transitions to an In-pit TSF after year 10, referred to as Tailings Dam Pit (TDP). TDP is located in the northern portion of MLA When Dam TDNA reaches capacity, fine tailings will then be pumped to the TDP. The TDP will then be able to accept fine tailings for the remainder of the mine s life, up to mine year 30. This transition is represented in the SWMS by TDP, which becomes functional after mine year 10. The capacity of TDP is therefore zero for all mine years up to year 10. At mine year 10, the dam s capacity is 51,700 Ml, which is then gradually reduced over time due to filling with fine tailings. At the end of mining in mine year 30, the capacity of the dam is reduced to 10,250 Ml. The gradual reduction in the capacity of this tailings dam is accounted for in the SWMS. Due to the predicted high salinity (median Total Dissolved Solids 3,010 mg/l) of the water stored in the dam, this dam will be classified with a significant hazard category in accordance with the Manual for Assessing Hazard Categories and Hydraulic Performance of Dams (DERM 2012). Emergency releases from this dam will be directed to the Horse Creek receiving waters. However, the prioritised pumping order for this dam will be as follows: Priority 1 Destination: CHPP water demand Elimatta Project

21 Priority 2 Destination: North water fill point demand Priority 3 Destination: South water fill point demand Priority 4 Destination: Controlled release to Horse Creek The characteristics of TDP are summarised in Table Table 5.21 Dam Characteristics TDP Mine Staging Year Dam Capacity (Ml) Transfer Pumping Rate (L/s) Transfer Pumping Destination Controlled Release Rate (L/s) Controlled Release Trigger Volume (%) n/a CHPP ,700 10, North Water Fill Point (WFPN1) South Water Fill Point (WFPS1) 0 0 Raw Water Dam - RW1 Raw Water Dam RW1 is located in the northern portion of MLA 50270, north of the MIA and east of the tailings dams. The capacity of Raw Water Dam RW1 is 200 Ml for all mine staging years. Controlled flow releases and uncontrolled overflows from this dam will be directed to the Horse Creek receiving waters. However, the prioritised pumping order for this dam will be as follows: Priority 1 Destination: Potable demand Priority 2 Destination: CHPP demand Priority 3 Destination: North water fill point demand Priority 4 Destination: South water fill point demand Priority 5 Destination: Controlled release to Horse Creek The characteristic of Raw Water Dam RW1 are summarised in Table Elimatta Project

22 Table 5.22 Dam Characteristics RW1 Mine Staging Year Dam Capacity (Ml) Transfer Pumping Rate (L/s) Transfer Pumping Destination Controlled Release Rate (L/s) Controlled Release Trigger Volume (%) 30 Potable Demand 100 CHPP Demand North Water Fill Point (WFPN1) South Water Fill Point (WFPS1) Sediment Dam - SD1 Sediment Dam SD1 is located in the northern portion of MLA 50254, near Pit N. Based on the predicted low salinity (median Total Dissolved Solids 1,194 mg/l) of the water stored in the dam, this dam will be not be classified as a hazardous dam in accordance the Manual for Assessing Hazard Categories and Hydraulic Performance of Dams (DERM 2012). The capacity of Sediment Dam SD1 is 100 Ml for all mine staging years. Controlled flow releases and uncontrolled overflows from this dam will be directed to the Horse Creek receiving waters. However, the prioritised pumping order for this dam will be as follows: Priority 1 Destination: South water fill point demand Priority 2 Destination: Controlled release to Horse Creek The characteristic of Sediment Dam SD1 are summarised in Table Table 5.23 Dam Characteristics SD1 Mine Staging Year Dam Capacity (Ml) Transfer Pumping Rate (L/s) Transfer Pumping Destination South Water Fill Point (WFPS1) Controlled Release Rate (L/s) Controlled Release Trigger Volume (%) 0 0 Sediment Dam - SD2 Sediment Dam SD2 is located in the north eastern portion of MLA 50254, near Pit E1. Due to the Elimatta Project

23 predicted low salinity (median Total Dissolved Solids 1,566 mg/l) of the water stored in the dam, this dam will not be classified with a significant hazard category in accordance with the Manual for Assessing Hazard Categories and Hydraulic Performance of Dams (DERM 2012). The capacity of Sediment Dam SD2 is 250Ml for all mine staging years. Controlled flow releases and uncontrolled overflows from this dam will be directed to the Horse Creek receiving waters. However, the prioritised pumping order for this dam will be as follows: Priority 1 Destination: South water fill point demand Priority 2 Destination: Controlled release to Horse Creek The characteristic of Sediment Dam SD2 are summarised in Table Table 5.24 Dam Characteristics SD2 Mine Staging Year Dam Capacity (Ml) Transfer Pumping Rate (L/s) Transfer Pumping Destination South Water Fill Point (WFPS1) Controlled Release Rate (L/s) Controlled Release Trigger Volume (%) 0 0 Sediment Dam - SD3 Sediment Dam SD3 is located in the south western portion of MLA 50254, near Pit W. Due to the predicted low salinity (median Total Dissolved Solids 1,220 mg/l) of the water stored in the dam, this dam will not be classified with a significant hazard category in accordance with the Manual for Assessing Hazard Categories and Hydraulic Performance of Dams (DERM 2012). The capacity of Sediment Dam SD3 is 125 Ml for all mine staging years. Controlled flow releases and uncontrolled overflows from this dam will be directed to the Horse Creek receiving waters. However, the prioritised pumping order for this dam will be as follows: Priority 1 Destination: South water fill point demand Priority 2 Destination: Controlled release to Horse Creek The characteristic of Sediment Dam SD3 are summarised in Table Table 5.25 Dam Characteristics SD3 Mine Staging Year Dam Capacity (Ml) Transfer Pumping Rate (L/s) Transfer Pumping Destination South Water Fill Point (WFPS1) Controlled Release Rate (L/s) Controlled Release Trigger Volume (%) 0 0 Elimatta Project

24 Raw Water Dam - RW2 Raw Water Dam RW2 is located in the south eastern portion of MLA 50254, east of Pit E2. This dam will be located upstream of the advancing high wall for mine Pit E2. The dam will only be required during mine years 3 to 25. Up to mine year 3, this natural catchment will freely drain to Horse Creek without any interference from the mine pits. However, at mine year 3, mine Pit E2 will effectively trap this catchment upstream of the pit s high wall. Based on a review of the site s natural topography, it is not practical to divert this catchment around the advancing mine Pit E2, due to the extensive earthworks required for such diversions. It is therefore proposed to construct a dam embankment across the gully upstream of the pit s high wall and capture the runoff from the local catchment at this location. The boundary of this local catchment is largely contained within the boundary of Elimatta MLA Due to the eastern advance of the high wall for mine Pit E2, the size of this local catchment will gradually reduce with time, until it will completely disappear after mine year 25. In the final mine landform at mine year 30, the dam will not be required, as the local catchment will be largely comprised of rehabilitated worked spoil and the final surface levels will freely grade west towards the Horse Creek watercourse. The capacity of raw water dam RW2 varies from zero to 9620 Ml depending on the mine staging year. This dam is only required during mine years 5 to 25. Based on the predicted low salinity (median Total Dissolved Solids 629 mg/l) of the water stored in the dam, this dam will be not be classified as a hazardous dam in accordance with the Manual for Assessing Hazard Categories and Hydraulic Performance of Dams (DERM 2012). Controlled flow releases from this dam will be directed to Horse Creek receiving waters. Uncontrolled overflows from this dam will be directed to mine pit E2. However, the prioritised pumping order for this dam will be as follows: Priority 1 Destination: South water fill point demand Priority 2 Destination; Controlled release to Horse Creek The characteristics of Raw Water Dam RW2 are summarised in Table Table 5.26 Dam Characteristics RW2 Mine Staging Year Dam Capacity (Ml) Transfer Pumping Rate (L/s) Transfer Pumping Destination Controlled Release Rate (L/s) Controlled Release Trigger Volume (%) n/a South Water Fill Point WFPS n/a 0 0 Elimatta Project

25 Raw Water Dam - RW3 Raw Water Dam RW3 is located in the north eastern portion of MLA 50254, east of pit E1. This dam will be located upstream of the advancing high wall for mine Pit E1. The dam will only be required during mine years 5 to 15. Up to mine year 5, this natural catchment will freely drain to Horse Creek without any interference from the mine pits. However, at mine year 5, mine Pit E1 will effectively trap this catchment upstream of the pit s high wall. Based on a review of the site s natural topography, it is not practical to divert this catchment around the advancing mine Pit E1, due to the extensive earthworks required for such diversions. It is therefore proposed to construct a dam embankment across the gully upstream of the pit s high wall and capture the runoff from the local catchment at this location. The boundary of this local catchment is largely contained within the boundary of Elimatta MLA Due to the eastern advance of the high wall for mine Pit E1, the size of this local catchment will gradually reduce with time, until it will completely disappear after mine year 15. After mine year 15 the dam will not be required, as the local catchment will be largely comprised of rehabilitated worked spoil and the final surface levels will freely grade west towards the Horse Creek watercourse. The capacity of raw water dam RW3 varies from zero to 140 Ml depending on the mine staging year. This dam is only required during mine years 5 to 15. Based on the predicted low salinity (median Total Dissolved Solids 326 mg/l) of the water stored in the dam, this dam will be not be classified as a hazardous dam in accordance with the Manual for Assessing Hazard Categories and Hydraulic Performance of Dams (DERM 2012). Controlled flow releases from this dam will not be permitted. Uncontrolled overflows from this dam will be directed to mine Pit E1. The characteristic of Raw Water Dam RW3 are summarised in Table Table 5.27 Dam Characteristics RW3 Mine Staging Year Dam Capacity (Ml) Transfer Pumping Rate (L/s) Transfer Pumping Destination Controlled Release Rate (L/s) Controlled Release Trigger Volume (%) n/a Raw Water Dam RW n/a 0 0 Elimatta Project

26 Raw Water Dam (RW4) Raw water dam RW4 is located in the south western portion of MLA 50254, west of Pit W. This dam will be located upstream of the advancing high wall for mine Pit W. The dam will only be required during mine years 3 to 20. Up to mine year 3, this natural catchment will freely drain to Horse Creek without any interference from the mine pits. However, at mine year 3, mine Pit W will effectively trap this catchment upstream of the pit s high wall. Based on a review of the site s natural topography, it is not practical to divert this catchment around the advancing mine Pit W, due to the extensive earthworks required for such diversions. It is therefore proposed to construct a dam embankment across the gully upstream of the pit s high wall and capture the runoff from the local catchment at this location. The boundary of this local catchment is largely contained within the boundary of Elimatta MLA Due to the western advance of the high wall for mine Pit W, the size of this local catchment will gradually reduce with time, until it will completely disappear after mine year 20. In the final mine landform at mine year 30, the dam will not be required, as the local catchment will be largely comprised of rehabilitated worked spoil and the final surface levels will freely grade east towards the Horse Creek watercourse. The capacity of raw water dam RW4 varies from zero to 140 Ml depending on the mine staging year. This dam is only required during mine years 3 to 20. Based on the predicted low salinity (median Total Dissolved Solids 321 mg/l) of the water stored in the dam, this dam will be not be classified as a hazardous dam, in accordance with the Manual for Assessing Hazard Categories and Hydraulic Performance of Dams (DERM 2012). Controlled flow releases from this dam will not be permitted. Uncontrolled overflows from this dam will be directed to mine pit W. The characteristic of Raw Water Dam RW4 are summarised in Table Table 5.28 Dam Characteristics RW4 Mine Staging Year Dam Capacity (Ml) Transfer Pumping Rate (L/s) Transfer Pumping Destination Controlled Release Rate (L/s) Controlled Release Trigger Volume (%) n/a Raw Water Dam RW n/a 0 0 Elimatta Project

27 2.12 WATER DISCHARGE It is intended that controlled releases from water storage dams will be allowed to discharge into the Horse Creek receiving waters. Controlled releases would only be allowed provided that they satisfy EHP s flow release criteria, stipulated in the Model Water Conditions for Coal Mines in the Fitzroy Basin (EHP 2013). The flow release criteria are based on a combination of minimum passing flow rate and water quality criteria. Based on the intent of the Fitzroy Flow Release Manual, the following flow triggers have been determined for the Horse Creek receiving waters No / Low Flow Release Trigger The no/low flow trigger (good quality mine affected water) for Horse Creek has been determined as follows: Release is only permitted when flows in the Horse Creek receiving waters are on the tail end of a flow event. That is, release is permitted only following a flow in the creek which has risen to a level above a specified event flow trigger and has then fallen below the flow trigger again. This scenario will then commence a release window of 28 days during which the release of good quality mine water can occur. From the assessment of EC versus flow interaction, the adopted flow event trigger for Horse Creek corresponds to the 50 percentile daily flow rate, which is 0.05 m 3 /s (5 ML/day) immediately upstream of the mine site. An event flow trigger value of 0.05 m 3 /s will be impossible to measure with a stream flow gauge constructed on the mobile creek bed of Horse Creek. A more realistic event flow trigger of 1.0 m 3 /s has therefore been adopted as being appropriate for the Horse Creek watercourse. The end of pipe water quality of the mine water must be less than or equal to the long term background reference 75 th /80 th percentile EC in the receiving waters. The 80 percentile EC for the Dawson River was calculated as 380 µs/cm (TDS 250 mg/l). This value was considered appropriate for the Horse Creek watercourse. The duration of the release is to be limited. In a dry ephemeral watercourse, the duration of the release must not exceed 28 days after the flow in the receiving waters falls below the event flow trigger. No volume/rate limits have been specified for the no/low flow release trigger. Medium Flow Release Trigger The medium flow trigger (medium quality mine affected water) for Horse Creek has been determined as follows: Release is only permitted when flow in the Horse Creek receiving waters is above a specified flow trigger, which must be representative of event flow and be above the base/low flow. From the assessment of EC versus flow interaction, the adopted flow event trigger for Horse Creek corresponds to the 50 percentile daily flow rate, which is 0.05 m 3 /s (5 ML/day) Elimatta Project

28 immediately upstream of the mine site An event flow trigger value of 0.05 m 3 /s will be impossible to measure with a stream flow gauge constructed on the mobile creek bed of Horse Creek. A more realistic event flow trigger of 1.0 m 3 /s has therefore been adopted as being appropriate for the Horse Creek watercourse. Two medium flow release triggers have been specified. The first release trigger (Med1) corresponds to a minimum event flow trigger of 1.0 m 3 /s, plus a maximum end of pipe water quality (EC) of 1,500 µs/cm (1,000 mg/l) for the mine affected water to be released. The corresponding maximum release rate for the Med1 release trigger is 0.6 m 3 /s. This is based on: Q trigger x (EC instream EC trigger ) / (EC EOP EC instream. The second release trigger (Med2) corresponds to a minimum event flow trigger of 2.0 m 3 /s, plus a maximum end of pipe water quality (EC) of 3,500 µs/cm (2,345 mg/l) for the mine affected water to be released. The corresponding maximum release rate for the Med2 release trigger is 0.4 m 3 /s. This is based on Q trigger x (EC instream EC trigger ) / (EC EOP EC instream ). The design dilution/maximum release rate should be based on a site-specific risk assessment. The maximum release rate should be designed to achieve an in-stream EC based on mid catchment (Zone 2) of EC instream = 700 µs/cm. High Flow Release Trigger The high flow trigger (poorer quality mine affected water) for Horse Creek has been determined as follows: Release is only permitted when flow in the Horse Creek receiving waters is above a specified high flow trigger, which must be representative of high event flow and must be above the medium flow. The 90 percentile flow rate in Horse Creek has been adopted for the high flow trigger. The 90 percentile flow rate for Horse Creek was calculated as 4.0 m 3 /s (346 ML/d). The high flow release trigger corresponds to a minimum event flow trigger of 4.0 m 3 /s, plus a maximum end of pipe water quality (EC) of 10,000 µs/cm (6700 mg/l) for the mine affected water to be released. The corresponding maximum release rate for the high flow release trigger is 0.2 m 3 /s, based on Q trigger x (EC instream EC trigger ) / (EC EOP EC instream ). The design dilution/maximum release rate should be based on a site-specific risk assessment. The maximum release rate should be designed to achieve an in-stream EC based on mid catchment (Zone 2) of EC in stream = 700 µs/cm 2.13 SITE WATER MANAGEMENT Water Management Strategy The overarching philosophy of the water management strategy prepared for the Project is to minimise any adverse impacts to the surrounding environment throughout the entire life of the mine. This goal is to be achieved by the adoption of a comprehensive best practice approach to the management of all water over the Elimatta Project site, comprising MLA 50254, MLA and MLA Elimatta Project

29 Water Management Strategies over the Southern MLA Over the southern MLA 50254, where all of the mining will actually occur, the following best practice management approaches have been incorporated into the water management strategy: 1. Minimise the impact on downstream watercourses by limiting the area to be disturbed at any one time. This will be achieved by careful mine stage planning, which minimises the footprint of the overall disturbed landform and in particular the footprint of the operating pits. 2. Capture all saline groundwater intercepted by the mine pits and prevent the unauthorised discharge of saline water into the Horse Creek receiving waters. In particular, 3 large environmental dams will be located throughout the southern Elimatta MLA 50254, to receive saline groundwater pumped from the operating mine pits. 3. Provision of separate clean water and contaminated water drainage systems to minimise the overall volume of contaminated water on the Project site. Provision of diversion drains and bunds to prevent clean water from draining into hazardous dams and sediment dams, thereby reducing the size of dams required on site. 4. Progressive and timing reinstatement of the disturbed landform. As the front of the mined pit advances, waste spoil overburden material and coarse rejects will be progressively placed back into the already worked pit void. The landforms of the spoil material placed back into the pit void will be shaped and reinstated in a timely manner and the batter slopes of all disturbed surfaces will be worked along the contour to minimise the likelihood of scour down the batter face. 5. The finished surface slopes of the re-shaped landforms will be graded to ultimately allow for natural runoff to freely drain into the Horse Creek receiving waters. 6. Prior to the establishment of a stable vegetative cover, runoff from the re-graded, but disturbed spoil landforms will be intercepted by localised diversion drains and runoff will be directed into sediment basins, to prevent the discharge of sediment laden turbid waters into the Horse Creek receiving waters. In particular, several sediment dams will be located throughout the southern Elimatta MLA 50254, to capture sediment laden runoff from proposed spoil dumps adjacent to the north pit, the west pit and the east pit. 7. Rehabilitation and revegetation of disturbed landforms will be undertaken as soon as is practical. Once landforms have developed a stable vegetative cover, the localised diversion channels can be decommissioned and runoff from the rehabilitated catchment slopes will be able to freely drain into the Horse Creek watercourse. 8. Minimise the risk of discharge of highly saline waters to the Horse Creek receiving waters by only permitting the release of water stored in the environmental dams, the sediment dams and the raw water dams throughout the Elimatta MLAs, in accordance with EHP (2013) model conditions for the discharge of mine affected water from coal mines in the Fitzroy Basin. 9. Minimise the risk of discharge of highly saline waters to the Horse Creek receiving waters by appropriately sizing the environmental dams, sediment dams and raw water dams throughout the Elimatta MLAs, to strictly limit the frequency and magnitude of uncontrolled overflows from the dams into the receiving waters. Elimatta Project

30 10. On site re-use and re-cycling of water shall be occur as standard operating procedure. The water captured in the Elimatta water management system shall be used to satisfy on site water demands arising due to potable needs, coal washing needs in the CHPP and for dust suppression needs. Use of the captured on site water shall be prioritised such that the higher salinity water is used in the first instance. This will reduce the likelihood of uncontrolled overflows of highly saline water to the Horse Creek receiving waters, by lowering stored water levels in the various storage dams. 11. Interference of natural catchments shall be avoided at all times. However, in some cases where natural catchments shall be unavoidably affected by the proposed mining activities and where the catchment boundaries are largely contained within the extent of the MLAs, interception of those natural catchments will be permitted. In such instances, the duration of the interference shall be minimised to reduce to enable the timely restoration of the natural drainage behaviour Water Management Strategy over the Northern MLAs and Over the northern MLA 50270, where all of the mine infrastructure will be located, the following best practice management approaches have been incorporated into the water management strategy: 1. Capture all contaminated runoff associated with the MIA and prevent the unauthorised discharge of saline water into the Horse Creek receiving waters. In particular, several environmental dams will be located in MLA 50270, to capture saline runoff from the MIA catchments. 2. Ensure that the tailings dams are appropriately sized to accommodate the expected volume of fine tailings output from the CHPP and to also minimise the frequency and magnitude of uncontrolled overflows into the Horse Creek receiving waters, at all times throughout the life of the tailings dams. 3. Ensure that sediment dams are provided along the route of the haul road linking the southern MLA with northern MLA, to prevent the discharge of sediment laden runoff from disturbed areas into the Horse Creek receiving waters. Road runoff may also pick up spilled coal product along the route of the transport corridor Expected Approval Requirements Several of the water storages will be considered hazardous under the Manual for Assessing Hazard Categories and Hydraulic Performance of Dams (DERM 2012). Dams which are assessed as having a hazard category of significant or high are regulated under the EP Act, which is administered by EHP. In addition, dams that are considered referable dams are regulated under the Water Supply (Safety and Reliability) Act 2008 which is administered by Department of Energy and Water Supply (DEWS). The Water Resource (Fitzroy Basin) Plan 2011 is also relevant to the development of the SWMS; however, Taroom Coal is not seeking a water allocation from the Fitzroy Basin under the Water Resource (Fitzroy Basin) Plan Taroom Coal will not require a water allocation when obtaining an external supply through an agreement with SunWater. The ownership of the water entitlement and the associated rights to supply remain with SunWater. However, a Water Licence under the Water Act 2000 will be required to take or interfere with groundwater for pit dewatering purposes which are integral to the safe operation of the Project. The development of the SWMS will impact upon overland flow in the Project area in an effort to separate clean and dirty water catchments and contain dirty water. Overland flow is covered in the Elimatta Project

31 Water Resource (Fitzroy Basin) Plan 2011, as follows: Overland flow water other than water in a spring connected to o o Artesian water; or Subartesian water connected to artesian water. For the Elimatta SWMS, the taking of overland flow water is limited to Raw Water Dams RW2, RW3 and RW4. The catchments draining to these dams are generally limited in size to the boundaries of the MLAs. These dams are required to prevent external catchment runoff from upstream of the pit high walls from overflowing into the operating pits. Individually, these dams have been designed to contain no more than 50 ML and as such do not trigger the taking of overland flow criteria in in the Water Resource (Fitzroy Basin) Plan These dams will ultimately be decommissioned when the mining progresses upstream in the catchments and eventually eliminates the catchments altogether Stormwater drainage Operational Stormwater Infrastructure Clean water diversion drains will be required surrounding disturbance areas to divert clean stormwater around sources of potential contamination. Figure 5.21 shows the standard design dimensions for the clean water diversion banks and channels to be constructed on the Project. Diversion channels will be sized in accordance with dimensions of the up slope catchment. Following significant rainfall events, all diversion works should be checked to ensure the structures have been able to sustain flow velocities without causing significant scour. Figure 5.21 Conceptual Design of Clean Water Diversion Drain Contaminated water will be pumped and diverted into the various water storages as outlined in Section In summary: Pit sumps will collect contaminated pit water and groundwater inflows, these sumps are then dewatered to local Environmental Dams EV1, EV2 and EV3 adjacent to the pit areas for the duration of pit operations; Potentially contaminated catchment areas within the MIA report to the five environmental dams within the MIA and TLO footprint which form Environmental Dam EV4 for the Elimatta Project

32 duration of the mine life; Sediment and runoff from the out-of-pit spoil dump in the north of MLA is captured in Sediment Dam SD1 for the duration of the mine life; Sediment and runoff from the initial box cut area and subsequent in-pit spoil dump in the northeast of MLA is captured in Sediment Dam SD2 for the duration of the mine life; Sediment and runoff from the out-of-pit spoil dump in the southwest of MLA is captured in Sediment Dam SD3 for the duration of the mine life; Raw Water Dam RW2 consists of an embankment dam in the south of MLA to capture clean water in advance of the pit highwall for years 5 to 25 of the mine life; Raw Water Dam RW3 consists of an embankment dam in the northeast of MLA to capture clean water in advance of the pit highwall for years 5 to 15 of the mine life; and Raw Water Dam RW4 consists of an embankment dam in the south western portion of MLA to capture clean water in advance of the pit highwall for years 5 to 25 of the mine life. In essence, the sediment dams (SD1, SD2 and SD3) may comprise a series of linked sediment ponds sized and operated as per the specifications detailed in Section These ponds are shown in the Mine Stage Plans provided in Section 2.4. This approach will ensure the capture of all potentially contaminated water in a system which is suited to the evolving landform topography throughout the life of the mine. Stormwater diversion and containment infrastructure for MLA as described above is shown in Figure 5.6 Figure Stormwater diversion and containment infrastructure for MLA is shown in the following figures. Figure 5.22 provides an overview of the MIA environmental dam network, known collectively as Environmental Dam EV4. This arrangement details the separation of clean and dirty water catchments and shows the likely path of diverted water flows. Figure 5.23 demonstrates the layout of the clean water diversion drain proposed to channel stormwater flows around Dam TDN. Figure 5.24 shows similar design details of Dam TDNA. Figure 5.25 shows the catchment areas which drain through the Infrastructure MLA Ultimately, these catchment areas drain under the train load out facility conveyor alignment and into Horse Creek. Allowances will be made during the construction of infrastructure alignments to provide for sufficient drainage capacity through culverts so as to maintain infrastructure integrity and minimise potential environmental impacts. Elimatta Project

33 N.B. Figure shows historic alignment of proposed Haul Road prior to the amendment of MLA boundary. Figure 5.22 MIA Water Management Infrastructure Elimatta Project

34 Figure 5.23 Northern TSF (TDN) Water Management Infrastructure Elimatta Project

35 Figure 5.24 Northern Alternative TSF (TDNA) Water Management Infrastructure Elimatta Project

36 N.B. Figure shows historic alignment of proposed Haul Road prior to the amendment of MLA boundary Figure 5.25 Infrastructure MLA Drainage Catchments Elimatta Project

37 2.14 RAIL & SERVICES CORRIDOR WATER MANAGEMENT The following water management infrastructure is proposed in order for the development of the WSL. As these activities will be undertaken outside of the MLA area, and will be carried out within a watercourse, lake or spring they will likely require authorisation via a Riverine Protection Permit under the Water Act Major Crossings Four major waterways impact the alignment of the proposed Rail and Services Corridor: Juandah Creek, Mud Creek, Spring Creek and either Horse Creek (south) or Horse Creek (north). Hydraulic modelling was undertaken to determine the flood extents and levels to inform bridge designs at waterway crossings. A number of potential bridge design options were collated and the afflux of the bridging structure on the flood levels was determined. Detailed bridge designs have not been completed, but the bridge design parameters adopted for the purpose of the hydraulic assessment are as follows: Bridge spans of 25 m; Singular piers with diameters of 1.2 m; Bridge width of 4 m; Abutment slopes of 1.5:1; and Bridge soffit to be a minimum of 600 mm above the 1,000 year ARI flood level. To determine requirements of bridge design, one-dimensional modelling was used for Spring Creek, while two-dimensional modelling was used for all other creeks. Based on the results of the modelled scenarios, the following recommendations were made for each crossing: A single 200 m wide opening (225 m long bridge) will be used for Juandah Creek, based on downstream afflux and velocities. This option has an afflux of 40 mm approximately 1 km upstream of the rail alignment in a 100 year event; A 150 m wide opening (175 m long bridge) with a culvert (1950 mm diameter of equivalent) on the tributary will be used for Mud Creek. A 100 year ARI has no afflux 1 km upstream of the rail alignment for this option, indicating that further reductions to the bridge span could be considered; Multiple openings are required for Horse Creek (south) due to the large proportion of conveyance outside of the main channel. Two 150 m wide openings (175 m long bridges) and one 100 m opening over the road (125 m long bridge) will be used for the southern alignment. For a 100 year event, this option has an afflux of 20 mm approximately 1 km upstream of the rail alignment; For Horse Creek (north), a 150 m wide opening (175 m long bridge) and one 75 m opening over the road (100 m long bridge) will be used. A 100 year ARI has an afflux of 69 mm approximately 1 km upstream of the rail alignment; and A 50 m wide opening (75 m bridge) will be used for Spring Creek. In a 100 year ARI, this Elimatta Project

38 option has an afflux of 50 mm approximately 150 m upstream of the rail alignment Minor Crossings To assess minor crossings not subject to hydraulic modelling, a culvert design spreadsheet based on the methodology provided in Waterway Design (AUSTROADS 1994) was used to determine peak design flows by probabilistic rational method. Pipe culverts have been designed, where possible, with a minimum 1.0 m cover for improved constructability, and a water level freeboard of 600 mm to the top of the rail. Culvert design also includes a minimum slope of 0.5% to ensure adequate drainage and self-cleansing velocity, and a minimum diameter of 900 mm. A summary of culvert sizes at each location is provided in Table 5.29 and a typical cross-section is shown in Figure Table 5.29 Culvert sizes at each location Culvert ID Culvert Size (mm) Number of Culverts Culvert Length CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD CD Elimatta Project

39 Culvert ID Culvert Size (mm) Number of Culverts Culvert Length CD CD CD CD2983N CD3050N CD3223N CD3299N CD3317N CD3709N CD3952N CD4048N CD2983S CD3050S CD3364S CD3609S CD6868S Figure 5.26 Typical culvert outlet cross-section 2.15 ROAD DIVERSION AND CONSTRUCTION Mine roads will be specific to the operation of the project and closed to public access. These roads will occur entirely within the boundaries of the MLAs and are described in Section Public roads, including those within the boundaries of the Project, will be temporarily closed, diverted or upgraded as detailed in Section Elimatta Project

40 Mine Roads As part of the construction phase, road developments within the MLA will occur to support the proposed operations. The construction of mine roads will involve the formation of the haul road, through MLA 50271, for ROM transport from the pit area to the CHPP. The haul road will be approximately 4.04 km long and built in accordance with industry standards at a width of 27 m with earth side bunds appropriate for the proposed haul truck specifications. Developments during the construction phase will also involve the establishment of mine service roads. These roads will be segregated, so as to separate vehicle types, and built according to the specifications required for individual vehicles (light vs. heavy). Mine service roads will serve primarily for the movement of light vehicles between mine infrastructure areas and will be designed in accordance with Austroads Guide to Road Design (Austroads 2010). The mine service road network will also include the access road from Perretts Road to the MIA area. Typically, mine roads are usually for mine use only and only available for general use under defined circumstances. All of the internal mine roads will be constructed during Year -1 for commissioning prior to the commencement of the operational phase Public Roads Mining Lease Areas There are a number of formed roads across and around the proposed mine under the control of Western Downs Regional Council (WDRC) that provide a service to local traffic. The development of the proposed mine will result in a number of temporary road closures, new sections of road and road relocations within and adjacent to the MLA areas. The purpose of the public road openings and closures is to allow mine operations to occur and provide safe alternative public traffic movement for road registrable vehicles with minimum disruption to existing patterns of movement. Roads which are directly affected by the project are highlighted in Figure 5.27 and listed below: The existing Perretts Road alignment, between Bundi Road and Ryals Road, runs through the middle of the proposed pit area in MLA This section of Perretts Road is to be temporarily relocated to the east, outside of the MLA area; Part of Ryals Road across Horse Creek to Perretts Road is to be upgraded; Part of the existing alignment of Perretts Road between Ryals Road and Cattle Camp Road, in the vicinity of MLA 50270, is to be upgraded; Cattle Camp Road is to be upgraded to provide access to the Accommodation Village and service public access from Perretts Road to the western side of the MLA areas; Goldens Road, along the southern boundary of MLA 50270, will be closed to facilitate development of the mine haul road; and A section of new road, linking Goldens Road to Cattle Camp Road, will be developed to maintain access between the western side of the MLA areas and Perretts Road. The timing of the public road relocations and closures is dependent upon design and construction Elimatta Project

41 approval from the WDRC. It is envisaged that all public road works will be constructed during Year -1 for commissioning prior to the commencement of the operational phase of the Project. Figure 5.27 Proposed Public Roads Closures and Upgrades Rail and Services Corridor Construction of the WSL and associated infrastructure, including access roads, will involve alterations to road infrastructure, including one State-controlled road crossing (Leichhardt Highway) and five local road crossings under WDRC jurisdiction. Road crossings required for the preferred rail alignment are Elimatta Project

42 detailed in Table Detailed crossing locations however are subject to further rail alignment development and approvals from the DTMR and WDRC. Approximate Chainage (m) Table 5.30 Public Road Crossings Location Treatment Comments 750 Nathan Road Road over rail 7200 Leichhardt Highway and Booral Road / No.1 Lane Road over rail Grosmont Road Road over rail Kabunga Road Public level crossing Perretts Road Road over rail Alignment is in cut of 5.0 m; Road realignment is required to achieve clearances and improve skew angles; Sealed pavement. Alignment is in cut of 2.0 m; Leichhardt Hwy bridge approach works are required to achieve clearances; Sealed pavement. Alignment is in cut of approximately 5.7 m; Sealed pavement. Crossing location to be confirmed in future design stages; Un-sealed pavement. Alternative crossing location to be confirmed in future design stages; Sealed pavement. Further alterations include stock route crossings and occupational (private) crossings. The number of stock and occupational crossings is subject to ongoing consultation with landowners and relevant stakeholders. Stock routes ordinarily used for travelling stock or declared to be a stock route under regulation are shown in Table 5.31, along with the suggested treatment. Table 5.31 Stock Route Crossings Approximate Chainage (m) Treatment Comments/Use Level crossing Vehicle and machinery movements Stock crossing* Note * denotes grade separated Stock movements, including a stock route diversion Access for land owners will be maintained during construction and operation phases of the Project and will be negotiated on a case by case basis. Where allowable, crossings will be constructed in the same location as the existing access, however, where it is not safe to do so, an alternative location will be considered. Where landscape conditions allow, occupational or private stock crossings will also be provided at rail level. The timing of public road rail crossing construction will vary but it is likely that construction will take approximately 6-9 months from commencement to completion during the initial stages of the construction period. Due to the interaction with rail alignment and crossings, it is expected work on Elimatta Project

43 individual crossings will be staged as required POWER SUPPLY The local Ergon power network around the Project area is typically a rural Single Wire Earth return network which does not have capacity to deal with the power loads required for construction or operation. Consequently, onsite power generation, through the use of diesel mobile generators, will be utilised during the early construction phase of the Project. This will be replaced with a permanent grid connection to either the Wandoan or Wandoan South substations as soon as possible within the construction stage Construction Power Demand Power will be required at the administration/construction offices, accommodation village and sewage treatment plants. The maximum energy demands required during the construction phase are calculated based on the following assumptions: Administration/construction offices located at the MLA areas and on the Rail and Services Corridor 75 volt-ampere (VA) per square metre (m 2 ); Accommodation village, 2.5 kilovolt-amperes (kva) per head (560 x kva); and, Sewage treatment plant 48 kva. Based on this, it is envisaged that the energy consumption per month will be approximately 759 MegaWatt hours (MWh) during construction. Initially diesel generators will be utilised during the early construction period as the major power source. Some of these generators will remain on site after mains power supply has been connected and will provide a backup power supply in the event of a failure of the grid supply. These back up units will power emergency service requirements only and will not have sufficient capacity to maintain production operations Operations Power Demand The peak permanent power demand during operational periods is approximately 13,550 kilowatt (kw) with an average of 11,590 kw. Based on these figures the annual energy usage has been calculated to be 75,000 MWh. Determination of overall site maximum demand is calculated by looking at the accommodation village, CHPP, MIA, and environmental dam loads to appropriately size the substation transformers. Load sources and operating hours are detailed in Table Elimatta Project

44 Table 5.32 Load Sources and Operating Hours Load Source Accomm. Village Water Management Peak Load (kw) Avg. Load (kw) Year 1 Year 2 Estimated Annual Usage (hours) Year 3 Year 4 Year 5 Year 6 Year 7 - EOM CHPP Train Load Out Total Grid Connection Infrastructure Taroom Coal has made an application with Ergon Energy Limited (Ergon) for a connection to infrastructure in the Wandoan area to provide the Project s energy requirements. Powerlink Queensland and Ergon are developing major power infrastructure in the Wandoan South area to service CSG and coal resource development. Elimatta has grid connection options to Ergon substations located at Wandoan (via the Rail and Services Corridor) and Wandoan South (via proposed corridors under consideration by Ergon). The connection routes from either sub-station location are still being investigated by Ergon. The corridor and infrastructure will be developed and operated by Ergon to a connection point on the mine site. Approvals associated with the development of this infrastructure will be the responsibility of the service provider. The permanent power supply to the Project will be via a 66 kv high voltage connection. The proposed electrical system in the operational phase will include a 66/11 kv mine substation which will supply: 11 kv CHPP switch-room (prefabricated offsite); 1 MVA (11/0.433 kv) MIA kiosk substation; 100 kva (11/0.433 kv) pole top transformer for the Environmental Dam; and 3 x 500 kva (11/0.433 kv) Accommodation Village kiosk substations. Two 20 MVA transformers will be installed in the mine substation to allow for n-1 redundancy and maintenance of transformers while the mine is still operational. In order to supply the Project with a permanent power connection there is considerable infrastructure required as described below: Elimatta Project

45 Mine Substation Infrastructure: Earthworks and gravel access roads; Earth grid, electrodes, and equipotential bonding; Lightning protection system; Plinths, bunding and foundations; Compound fencing; Area lighting; 2 off 15 MVA 66/11 kv transformers (operating in standby/duty configuration) including neutral earthing resistors (NERS); 66 kv air-insulated switch (AIS) gear; 11 kv AIS gear; 11 kv outdoor bus work; and Single control room housing feeder protection, transformer protection and local station backup supplies. CHPP Switch Room Infrastructure: Earthworks and gravel access roads; Earth grid, electrodes, and equipotential bonding; Lightning protection system; Plinths, bunding and foundations; Area lighting; and 11 kv ground-insulated switchroom and switchgear, housing feeder protection, transfer protection and local station back-up supplies. MIA infrastructure: 1 off kiosk substations (11/0.433 kv, 1000 kv, 11 kv ring main unit (RMU) included); Plinths, bunding and foundations; Earth grid and electrodes; Switchboard plinths; Switch boards (From 3B, 50 ka, IP 66); and Elimatta Project

46 Cabling (switchboard - kiosk). Environment Dam Infrastructure: 1 off pole top transformer (11/0.433 kv, 100 kva); Foundations; Earth grid and electrodes; Switchboards/Motor Control Centre (MCC); and Cabling. Accommodation Village Infrastructure: 3 off kiosk substations (11/0.433 kv, 500 kva, 11 kv RMU included); Plinths, bunding and foundations; Earth grid and electrodes; Switchboard plinths; Switch boards (Form 3B, 50 ka, IP 66); and Cabling (switchboard-kiosk). 11kV reticulation infrastructure: 11kV overhead/underground reticulation connecting mine substation to: o o o o MIA kiosk; Accommodation village; CHPP switch-room; and Train Load Out. WSL Corridor: Power supply for all signalling, telecommunications and train control will be sourced from the nearest power utility. Way side detectors for dragging equipment hotboxes etc. will be solar/battery operated FUEL AND HYDROCARBON STORAGE Fuel and oil will be stored on site within bulk storages and will be used to operate various fixed plant and mobile equipment. The types and amounts of fuel to be stored onsite will include; Elimatta Project

47 Fuel: 7 x 150,000 L horizontal diesel tanks Oil: 1 x 35,000 L hydraulic oil 1 x 35,000 L engine oil 1 x 35,000 L waste oil 1 x 20,000 L transmission oil 1 x 15,000 L gear oil 1 x 15,000 L final drive oil 1 x 15,000 L premixed coolant 1 x 10,000 L waste coolant Additional fuel and oil storage will be developed onsite to allow for two 150,000 L vertical fuel storage tanks and two 25,000 L oil storage tanks. The storage area will be fenced and bunded. The bund and its associated pipe work, valves, and drainage will be designed to AS1940. The MIA area will also house several Drum Store Facilities ACCOMMODATION VILLAGE The accommodation village both during construction and operation of the Project will be located on site approximately 1.7 km north of the CHPP. The construction village, servicing the mine and Rail and Services Corridor construction workforce, will be in commission for 24 months and will be then converted to accommodate the requirements of the operational village. The village will essentially be developed from the relocatable buildings. The mess and recreational facilities from the construction village will have been designed to ensure minimal modifications are required when village is converted from construction facilities to that of the operations village. The village will initially consist of approximately 300 beds, increasing during the Project life to accommodate workforce increases. An extra 60 beds will be available for occasions such as CHPP shut downs and other major operations throughout the mine life. The accommodation strategy allows for no room sharing and will reflect prevailing industry standards at the time off commissioning WORKSHOPS AND OFFICES The Heavy Mining Equipment (HME) workshop building will be centrally located within the MIA, servicing heavy mining vehicles and equipment, and other general mine associated infrastructure that will be developed as part of the MIA. The HME will have four main sections; maintenance bays designed with a nominal size of 12 m x 20 m, tyre bays, local store areas, and office space with five open plan work stations. Office facilities and crib rooms will be located in the MIA area and along the Rail and Services Corridor Elimatta Project

48 during construction SEWERAGE TREATMENT There are no existing facilities for the treatment of sewage in the vicinity of the Project. All sewage generated on site will be treated on site at a packaged STP located proximate to the accommodation village, where the bulk of the sewage will be generated. Sewage generated at the MIA and CHPP will be pumped to the STP by way of underground packaged sewage pump stations and buried rising mains. Treated waste water from the STP will be monitored monthly for contaminants in accordance with the Project s EA, prior to being disposed of via low height sprays in a proposed irrigation area situated east of the accommodation village access road. The proposed area has been assessed against Environmental Guideline: Use of Effluent by Irrigation (Department of Environment and Conservation (NSW) 2003) in terms of soil suitability, groundwater vulnerability, surface water and flood potential. Soils in the proposed area of irrigation have been classified as the Cheshire Soil Management Unit and are consistent with descriptions provided in the Land Management Field Manual Wandoan District (Gray and Macnish 1985) comprises of brown to black non-cracking clay with depths exceeding 600 mm. Soil chemistry indicates a soil which is mildly to moderately alkaline in ph. At the surface the soil has mostly low levels of major soil nutrients and organic carbon but has a high to very high cation exchange capacity (CEC) and is well structured and stable. Surface soils are non-saline and non-sodic before becoming sodic at 300 mm. The depth of useable soil resources extends to approximately 300 mm before sodicity and salinity potentially constrains usability. Landscapes of the Cheshire SMU consist of the upper to mid slopes of gently undulating plains which have been extensively cleared for agriculture. Flood modelling has confirmed that the area selected for effluent irrigation is unaffected by a 100 annual reoccurrence interval (ARI) event. The characteristics of this area comply with the recommendations of the Environmental Guideline: Use of Effluent by Irrigation (Department of Environment and Conservation (NSW) 2003). An effluent disposal system will be implemented to ensure that spray drift does not occur to any sensitive or commercial place. This will be achieved by the use of low pressure sprays with a greater number of spray nozzles for the required disposal area. In addition, the design of the system will take into account the need to ensure no runoff from the disposal area takes place. Environmental Guideline: Use of Effluent by Irrigation (Department of Environment and Conservation (NSW) 2003) was used to calculate the approximate area (ha) required for the allocation of treated effluent from the STP. The minimum irrigation area required based on organic loading was estimated using the following formula: A = CQ / (1,000 x Lc) Where: A = irrigation area (ha) C = concentration of BOD 5 (mg/l) Q = average effluent flow rate (kl/month) Lc = critical loading rate of constituent (kg/ha/month) Based on the assumption that the average loading rate of most soils is 1,500 kg/ha/month, the minimum irrigation area calculated was to be 133 m 2. Elimatta Project

49 The STP has been designed to produce Class A effluent and will be developed in accordance with the Planning Guidelines for Water Supply and Sewerage (DEWS 2010) and the Queensland Water Recycling Guidelines (EPA 2005). The STP will be designed to encompass the following: 100% of the potable water (240 L per capita per day) will become waste water and returned to the STP for treatment; Treatment plant capacity sufficient to allow for treatment of all flows over a 20 hour period; Pump stations will be designed for peak wet weather inflows; and Pumps and rising mains are to have capacity to deliver twice the peak incoming flow rates. Two treatment plants will be required; a permanent base load plant and a temporary plant to accommodate the peak loads. Temporary facilities, such as portaloos, will be installed at major construction sites and replaced every 2 3 days for disposal at an authorised treatment plant RUBBISH DISPOSAL General mine waste (other waste rock and washery waste), that cannot be recycled or reused, will be removed from site by contractors or disposed of in an on-site landfill. If required, the rubbish disposal site (landfill) will be located on MLA It is assumed that each person will create 1.5 t of general waste for disposal at the rubbish disposal site per annum. With an estimated maximum of 150 personnel on site at any one time during peak operation the amount of general waste created will be approximately 225 tpa. This equates to approximately 1,125 m 3 of landfill volume per year with an equivalent surface area of 24 m x 24 m (assuming 2 m depth). The rubbish disposal site will be selected in accordance with the EHP EcoAccess Guideline Landfill Siting, Design, Operation and Rehabilitation. Odour at the rubbish disposal site will be managed by regularly covering the waste with soil (at least fortnightly during peak operations). The disposal site will be progressively developed in compartmentalised cells to minimise the active face and reduce potential for windblown rubbish. The disposal site will be managed such that stormwater runoff is directed away from disposal cells and any direct rainfall is captured and evaporated, rather than being released to the environment. The rubbish disposal site will be monitored through regular visual assessments to ensure long term environmental performance Construction Material During the construction period, approximately 200 truckloads per week of plant and bulk material will be imported to the Project site from within the local area and the major centres of Toowoomba, Brisbane and Gladstone. A large majority of these loads (98%) will be raw materials including clays, gravel, sand, coarse rock and aggregate that will be required during construction. Elimatta Project

50 Both Boral Limited (Boral) and Ostwald Bros. are exploring development opportunities for quarries within the region to meet the construction demands of the Elimatta Project and other projects in the area. Taroom Coal intends to source raw construction material from Boral Warrians Quarry located approximately 100 km southwest of Project site, off the Roma-Taroom Road at Euthulla and Ostwald Bros Knob Hill Quarry located approximately 120 km northeast of Project site, off Knudsens Road at Bungaban ENVIRONMENTALLY RELEVANT ACTIVITIES Table 5.33 describes the activities proposed to be conducted on the Project which would otherwise be ERAs as per Schedule 2 of the EP Regulation if the Project were not considered as a resource activity requiring an environmental authority. However, mining projects are covered separately under Schedule 2A of the EP Regulation and the Aggregate Environmental Score for the Project is shown in Table As the proposed Project is a Level 1 Mining Activity, the relevant Annual Fee payable for the Project is $29, reflected by Table Table 5.33 Activities associated with the Project that would otherwise be considered ERAs Environmentally Relevant Activity Threshold Chemical Storage Storing 200m 3 or more of chemicals that are liquids, other than chemicals mentioned in items 1 to 3 under Schedule 2, section 8, subsection (1)(d) Fuel burning Extractive and Screening Activities Crushing, milling, grinding or screening Fuel burning operation using equipment capable of burning at least 500 kg/hr Extracting more than 1,000,000 tpa of material; Screening more than 1,000,000 tpa of material More than 5,000t of materials in a year Mineral Processing Processing, in a year, the following quantities of mineral products, other than coke - more than 100,000t Bulk material handling Loading or unloading 100t or more of minerals in a day or stockpiling 50,000t or more of minerals Regulated Waste Storage Receiving and storing regulated waste Elimatta Project

51 Environmentally Relevant Activity Waste Disposal Sewage Treatment Threshold Waste disposal facility (regulated and general waste) <50,000 tpa Treatment Plant for > Equivalent Persons with effluent discharged from works to an infiltration trench or through an irrigation scheme Table 5.34 Mining Activities and Annual Fees Associated with the Project Activity Aggregate Environmental Score 13. Mining Black Coal REHABILITATION AND DECOMISSIONING Rehabilitation strategies and methods for the Elimatta Project were designed to meet the requirements of Section 203 of the EP Act and have been structured in accordance with the Guideline 18: Rehabilitation Requirements for Mining Projects (DERM 2011) and the Technical Guidelines for the Environmental Management of Exploration and Mining in Queensland (1995). In order to ensure best practice in all facets of rehabilitation, the Leading Practice Sustainable Development for the Mining Industry series of booklets has been used in the development of site specific rehabilitation methods, in particular: Leading Practice Sustainable Development Program for the Mining Industry Mine Closure and Completion (Commonwealth of Australia 2006a); Leading Practice Sustainable Development Program for the Mining Industry Mine Rehabilitation (Commonwealth of Australia 2006b); and Leading Practice Sustainable Development Program for the Mining Industry Tailings Management (Commonwealth of Australia 2007). Other guidelines that were consulted in the development of the rehabilitation strategies included: Guideline 16: Final and Progressive Rehabilitation and Audit Statements for Level 1 Mining Lease (DERM 2011); and Technical Guidelines for Open Pit Rehabilitation (DERM 1995) Rehabilitation Hierarchy The rehabilitation hierarchy for the Elimatta Project was developed in accordance with Guideline 18: Rehabilitation Requirements for Mining Projects (DERM 2011). The hierarchy, in order of decreasing capacity to prevent or minimise environmental harm is as follows: Elimatta Project

52 1. Avoid disturbance that will require rehabilitation 2. Reinstate a natural ecosystem as similar as possible to the original 3. Develop an alternative outcome with a higher economic value than the previous land use 4. Reinstate previous land use 5. Develop a lower value land use 6. Leave the site in an unusable condition or with a potential to generate future pollution or adversely affect environmental values The hierarchy allows for lower values to be acceptable when they will be appropriate to the stakeholders or when higher values are impractical. However, leaving the site in an unusable condition or with the potential to cause further environmental harm is not considered acceptable and has not been proposed for the Elimatta Project. Where disturbance cannot be practically avoided (hierarchy item 1), the overarching rehabilitation principal of the Elimatta Project is to remediate the disturbed area to a land use consistent with low intensity cattle grazing and reinstate riparian and temperate habitats. This reflects the natural ecosystems and land use of the site pre-mining, as per hierarchy item 2 and 4. It is expected that some disturbance areas, such as final voids, may achieve a reduced land value upon rehabilitation in accordance with hierarchy item 5. During the operational life of the mine consultation with stakeholders including local communities and government authorities may indicate a preference for an alternative post mining land use of higher economic value. If such a situation arises then NEC will investigate the options in consultation with these stakeholders. It is assumed that the Rail and Services Corridor infrastructure will be retained post decommissioning of the Elimatta Project as it will continue offer a significant benefit to resource developers, other land users and the general public. As result, Rail and Services Corridor infrastructure is not specifically addressed in this rehabilitation section Rehabilitation Goals The rehabilitation goals have been developed in accordance with Guideline 18: Rehabilitation Requirements for Mining Projects (DERM 2011). The goals of the rehabilitation are to return the Elimatta Project site to a state that is: Safe to humans and wildlife; Non-polluting; Stable; and Able to sustain the agreed post mining land use. Adoption of the rehabilitation goals aims to achieve long term maintenance of essential ecological processes for the Elimatta site, post mining. Elimatta Project

53 Mine Domain Objectives In order to achieve the described rehabilitation goals for the site, specific rehabilitation objectives have been developed for each individual mine domain. A mine domain is made up of land management units within a mine site that have similar characteristics. Six domains have been determined for the Project. The domain name and the mine areas included are detailed in Table Table 5.35 Elimatta Mine Domains Domain: Mine areas included: Final Voids Final Voids; and, In-Pit TSF (TDP) Exploration Areas Exploration Areas Dams Environmental Dams Raw Water Dams Sediment Dams Diversions Horse Creek Diversion Infrastructure Waste Disposal Buildings, including foundations; Roads; Chemical/fuel storages; and CHPP. In-pit dump; Out-of-pit dump; and, Surface TSFs (TDN and TDNA) Development of rehabilitation objectives, specific for the land disturbance type, is a requirement of Section 203 of the EP Act. Table 5.36 below describes the Elimatta Project rehabilitation objectives for each mine domain Rehabilitation Indicators Rehabilitation indicators have been developed for the Elimatta Project to provide measures of progress towards the mine domain rehabilitation objectives. In the case of the Project, some indicators have been deemed relevant to a number of domains whilst other indicators have only a local significance to one mine domain. Rehabilitation indicators for the Elimatta project are provided in Table Completion Criteria Completion criteria have been proposed for the Elimatta Project to provide standards for determining successful rehabilitation for each domain. Completion criteria take the form of a set of measurable benchmarks against which the rehabilitation can be compared to determine if the chosen objectives are being met. Evidence of the completion criteria having been addressed will be collected as part of the Elimatta Project

54 rehabilitation monitoring program (see Section ) to assist in determining rehabilitation success. The domains within the Project site are deemed to be successfully rehabilitated when completion criteria for each rehabilitation goal and objective have been met over a long term period. Table 5.36 outlines the completion criteria, indicators, objectives and rehabilitation goals proposed for the Elimatta Project. Elimatta Project

55 Table 5.36 Completion Criteria, Indicators, Objectives and Rehabilitation Goals Rehabilitation Goal Rehabilitation Objective Rehabilitation Indicator Completion Criteria Domain Final Void Safety barriers and signage assessed against requirements of the Coal Mining Safety and Health Act 1999 Evidence in rehabilitation report that all safety precautions have been taken in accordance with the relevant legislation All remaining voids are safe for humans and animals Safety assessment of final landform by an appropriately qualified person Evidence in rehabilitation report that safety precautions have been implemented in accordance with relevant legislation Domain Exploration Areas Safe Site Exploration sites are safe for humans and animals Safety assessment of rehabilitated site by an appropriately qualified person Evidence in rehabilitation report that ground is structurally safe Domain Infrastructure All infrastructure sites are safe for humans Safety assessments of final landform by an appropriately qualified person Certification in rehabilitation report that final landform is structurally sound and safe Domain Dams Safety assessment of final landform by an appropriately qualified person Certification in rehabilitation report that ground is structurally sound and safe to people and animals Dam sites are safe for humans and animals Safety barriers and signage assessed against requirements of the Coal Mining Safety and Health Act 1999 Evidence in rehabilitation report that all safety precautions have been implemented in accordance with the relevant legislation Elimatta Project

56 Rehabilitation Goal Rehabilitation Objective Rehabilitation Indicator Completion Criteria Domain Diversions Diversions are safe for humans and animals Safety barriers and signage assessed against requirements of the Coal Mining Safety and Health Act 1999 Safety assessment of final landform by an appropriately qualified person Evidence in rehabilitation report that all safety precautions have been taken in accordance with the relevant legislation Evidence in rehabilitation report that safety precautions have been implemented in accordance with relevant legislation Domain Waste Disposal Safety assessment of final landform by an appropriately qualified person Certification in rehabilitation report that landform is structurally sound and safe Waste disposal sites safe for humans and animals Exposure to and availability of heavy metals or any other toxic materials in the environment Evidence in the rehabilitation report that post closure monitoring (air, soil, water, stream sediments) shows the final landform is compliant with limits in the relevant Environmental Protection Policies or other agreed limits. Domain Final Void Safety assessment of final landform by an appropriately qualified person Certification in rehabilitation report that final landform is structurally sound and safe Non - polluting Hazardous and contaminated material adequately managed Rehabilitation monitoring plan in place to monitor void water quality, downstream surface water, groundwater and stream sediments Evidence in the rehabilitation report that post closure monitoring (void water, surface water, groundwater, stream sediments) shows the final landform is compliant with limits in the relevant Environmental Protection Policies or other agreed limits Elimatta Project

57 Rehabilitation Goal Rehabilitation Objective Rehabilitation Indicator Completion Criteria Hazardous material adequately managed Hazardous and contaminated material adequately managed Runoff and seepage will be of good quality water that is unlikely to affect known environmental values Dams to remain on closure will not contribute contaminants to the environment Rehabilitated dams will not contribute contaminants to the environment Hazardous and contaminated material adequately managed Domain Exploration Areas Site inspection by an appropriately qualified person Domain Infrastructure Contaminated Land Assessment undertaken Rehabilitation monitoring plan in place to monitor downstream surface/ground water Domain Dams Rehabilitation monitoring plan in place to monitor water in the dam and downstream surface/ground water Rehabilitation monitoring plan in place to monitor downstream surface/ground water Contaminated Land Assessment undertaken Domain Diversions Evidence in rehabilitation report that all exploration sites have been cleaned up and rehabilitated to an acceptable standard Evidence of remediated landform in a contaminated land assessment report. Evidence in rehabilitation report that monitoring data is meeting specified contaminant and trigger levels that ensure environmental values are not being compromised Evidence in the rehabilitation report that post closure monitoring (water quality) is compliant with limits in the relevant Environmental Protection Policies or other agreed limits. Evidence in the rehabilitation report that monitoring data meets specified contaminant and trigger levels Evidence of remediated landform in a contaminated land assessment report. Discharge will be of good quality water that is unlikely to affect known environmental values Rehabilitation monitoring plan in place to monitor downstream surface water Domain Waste Disposal Evidence in rehabilitation report that monitoring data is meeting specified contaminant and trigger levels that ensure environmental values are not being compromised Elimatta Project

58 Rehabilitation Goal Rehabilitation Objective Rehabilitation Indicator Completion Criteria Hazardous and contaminated material adequately managed Engineers assessment of cover or final landform design Rehabilitation monitoring plan in place to monitor downstream surface/ground water Engineers certification in rehabilitation report that the waste disposal site has been securely covered to prevent any release or seepage of hazardous or contaminated material Evidence in the rehabilitation report that monitoring data demonstrates the cover is functioning in preventing any release or seepage of hazardous or contaminated material Domain Final Voids Minimal probability of wall failure or rock falls that will cause significant environmental harm Geotechnical studies of final voids Risk assessment of final landform Evidence in rehabilitation report of geotechnical studies to determine whether final landform is stable Evidence in rehabilitation report that appropriate risk assessment and control measures have been undertaken Domain Exploration Areas Stable Landform Landform achieves appropriate erosion rates Engineers assessment of design and construction of structures to control water and sediment flow Evidence in rehabilitation report that required sediment control structures are in place and functioning correctly Vegetation cover to minimise erosion Vegetation assessment Evidence in the rehabilitation report that the revegetation meets the limits set by the analogue sites Domain Infrastructure Landform achieves appropriate erosion rates Engineers assessment of design and construction of structures to control water flow Engineer certification in rehabilitation report that infrastructure sites (both remaining and decommissioned) have the required structures to control water flow and runoff Elimatta Project

59 Rehabilitation Goal Rehabilitation Objective Rehabilitation Indicator Completion Criteria Vegetation cover to minimise erosion Vegetation assessment Evidence in the rehabilitation report that the revegetation meets the limits set by the analogue sites Minimal probability of subsidence that will cause significant environmental harm Vegetation cover to minimise erosion Minimal probability of subsidence that will cause significant environmental harm Vegetation cover to minimise erosion Minimal probability of subsidence or rock falls that will cause significant environmental harm Domain Dams Geotechnical studies of final landforms Risk assessment of final landform Vegetation assessment Domain Diversions Geotechnical studies of final landforms Risk assessment of final landform Vegetation assessment Domain Waste Disposal Geotechnical studies of final landforms Evidence in rehabilitation report of geotechnical studies to determine whether final landform is stable Evidence in rehabilitation report that appropriate risk assessment and control measures have been undertaken Evidence in the rehabilitation report that the revegetation meets the limits set by the analogue sites Evidence in rehabilitation report of geotechnical studies to determine whether final landform is stable Evidence in rehabilitation report that appropriate risk assessment and control measures have been undertaken Evidence in the rehabilitation report that the revegetation meets the limits set by the analogue sites Evidence in rehabilitation report of geotechnical studies to determine whether final landform is stable Elimatta Project

60 Rehabilitation Goal Rehabilitation Objective Rehabilitation Indicator Completion Criteria Risk assessment of final landform Evidence in rehabilitation report that appropriate risk assessment and control measures have been undertaken Vegetation cover to minimise erosion Vegetation assessment Evidence in the rehabilitation report that the vegetation type and density are of species suited to the slope, aspect, climate and other factors, and that the measured erosion rates meets the limits set by analogue sites Domain Final Voids Establish safe and stable waterbody with low risk of environmental harm Rehabilitation monitoring plan in place to monitor void water quality Evidence in rehabilitation report that monitoring data is meeting livestock contaminant limits and that no risk to wildlife exists Domain Exploration Areas Sustains agreed land use Soil properties that support desired land use Self-sustaining natural vegetation and habitat established Soil monitoring program in place to ensure remaining soil is able to support post-mining land use Vegetation assessment Evidence in rehabilitation report that all soil chemical, physical, and biological properties of are within acceptable limits that ensure soil is able to support postmining land use Certification within the rehabilitation report that key species are present, suitable diversity has been achieved and cover/density is adequate Certification within the rehabilitation report that the Pest and Weed Management Plan has been successful Domain Infrastructure Soil properties that support desired land use Soil monitoring program in place to ensure remaining soil is able to support Evidence in rehabilitation report that all soil chemical, physical, and Elimatta Project

61 Rehabilitation Goal Rehabilitation Objective Rehabilitation Indicator Completion Criteria Self-sustaining natural vegetation and habitat established For dams which are to remain on decommissioning, establish safe and stable water body with a low risk of environmental harm For dams to be rehabilitated, soil properties that support desired land use For dams to be rehabilitated, selfsustaining natural vegetation and habitat established Establish safe and stable waterway with a low risk post-mining land use Vegetation assessment Domain Dams Water quality established by monitoring or modelling validated by monitoring Structural report on integrity of structure Soil monitoring program in place to ensure remaining soil is able to support post-mining land use Vegetation assessment Domain Diversions Water quality established by monitoring or modelling validated by biological properties of are within acceptable limits that ensure soil is able to support postmining land use Certification within the rehabilitation report that key species are present, suitable diversity has been achieved and cover/density is adequate Certification within the rehabilitation report that the Pest and Weed Management Plan has been successful Evidence in the rehabilitation report that the dams meets water quality guidelines Engineers certificate of structure Evidence in rehabilitation report that all soil chemical, physical, and biological properties of are within acceptable limits that ensure soil is able to support postmining land use Certification within the rehabilitation report that key species are present Certification within the rehabilitation report that species diversity has been achieved Certification within the rehabilitation report that the Pest and Weed Management Plan has been successful Evidence in the rehabilitation report that the dams meets water Elimatta Project

62 Rehabilitation Goal Rehabilitation Objective Rehabilitation Indicator Completion Criteria of environmental harm monitoring quality guidelines Self-sustaining natural vegetation and habitat established Structural report on integrity of structure Vegetation assessment Domain Waste Disposal Engineers certificate of structure Certification within the rehabilitation report that key species are present, suitable diversity has been achieved and cover/density is adequate Certification within the rehabilitation report that the Pest and Weed Management Plan has been successful Soil properties that support desired land use Self-sustaining natural vegetation and habitat established Soil monitoring program in place to ensure remaining soil is able to support post-mining land use Vegetation assessment Evidence in rehabilitation report that all soil chemical, physical, and biological properties of are within acceptable limits that ensure soil is able to support postmining land use Certification within the rehabilitation report that key species are present, suitable diversity has been achieved and cover/density is adequate Certification within the rehabilitation report that the Pest and Weed Management Plan has been successful Progressive Rehabilitation Strategy The Elimatta Project is committed to undertaking progressive rehabilitation throughout the life of mine. The progressive rehabilitation strategy will target areas as soon as they become available for rehabilitation. This approach aims to minimise the total disturbance existing at any point in time during the life of the mine. Benefits of this approach include: Minimising erosion on the site; Minimising dust emission from the site; Reducing the time for which topsoil remains stockpiled leading to an increased regeneration Elimatta Project

63 from the seed bank; Minimising the ecological impacts of clearing, such as reduced habitat for fauna; and Minimising the social / visual impacts of the Project. Post Mining Land Use In accordance the rehabilitation hierarchy, rehabilitation of disturbed areas will primarily aim to reinstate a land condition as similar as possible to the pre-mining landscape. For a majority of the Project area, the proposed post-mining land use and condition will be consistent with the current primary land use of low intensity cattle grazing. Riparian habitats will be established along the length of the Horse Creek Diversion consistent with the rehabilitation outcomes proposed for the diversion. Confirmation of the success of rehabilitated area will be accomplished through the establishment of analogue and rehabilitation monitoring sites whereby measurable indicators will be assessed periodically to determine appropriate targets representative of the pre-mining land use. In accordance with the rehabilitation hierarchy and goals for the Elimatta Project, described in Table 5.36, the majority of the mine domains will be rehabilitated with the aim of recreating a land use consistent with low intensity cattle grazing. The diversion of Horse Creek will be rehabilitated to reinstate riparian and temperate habitats consistent with the pre-mining land use of this area Soil Management The Soil and Land Suitability Assessments for the Elimatta Project Mining Areas describe six Soil Management Units within the Elimatta Project area. These were classified as the Downfall, Kinnoul, Cheshire, Rolleston, Juandah and Horse Creek Alluvium Soil Management Units. Additional soil management units have been described over the Rail and Services Corridor. As described in Section , the multi-user infrastructure proposed for development within the Rail and Services Corridor is expected to remain as a functioning asset to local and regional users. As such, these additional soil units have not been included in this section. The Downfall, Kinnoul, Cheshire, Rolleston and Juandah units possess sodic subsoils with increasing levels of exchangeable sodium within the upper 900 mm of the profile. Salinity also increases with depth within these profiles, to levels considered moderate to highly saline by mm. An exception to this is the Horse Creek Alluvium SMU, with no signs of sodicity or salinity present within the profile. With the exception of the Horse Creek Alluvium SMU, the soils of the project site are all considered to have restrictions for stripping, stockpiling and rehabilitation. All soils present on the Project site are considered moderately deficient of major soil nutrients. As such, long term (in excess of 6 months) topsoil stockpiles will be ripped and seeded to maintain soil biota and a viable seed bank. Useable soil resources are mainly confined to the surficial horizons and locally in the upper part of the subsurface horizons which contain seed-stock, micro-organisms and nutrients necessary for plant growth. The following list presents the soil management units in terms of the quality of their topsoil resource (from most to least suitable) and outlines their recommended stripping depths: Horse Creek Alluvium Soil Management Unit 1000 millimetres; Cheshire Soil Management Unit 300 millimetres; Elimatta Project

64 Rolleston Soil Management Unit 200 millimetres; Downfall Soil Management Unit 200 millimetres; Kinnoul Soil Management Unit 100 millimetres; and Juandah Soil Management Unit 0 millimetres. The topsoil stripping and stockpiling strategy for the Elimatta Project will target the above soil depths for each Soil Management Unit on the site. In addition, the strategy will aim to: Minimise the time soil is stockpiled prior to it being used in rehabilitation; Minimise the transport distance between topsoil stripping and stockpiling; Stockpile topsoil up to a maximum of 2 m in height away from drainage areas, roads, machinery, transport corridors, and stock grazing areas; and Rip and seed with a quick establishment pasture, to limit erosion, and maintain a viable seed bank if the period of stockpiling is greater than one growing season or six months. Final Rehabilitated Landform of the Elimatta Project Figure 5.28 and Figure 5.29 below provides a layout of the Elimatta Project final landform. Details of rehabilitation strategies for each mine domain are discussed in the following sections. Elimatta Project

65 Figure 5.28 Elimatta Project Final Landform (MLA 50270, MLA 50271) Elimatta Project

66 Figure 5.29 Elimatta Project Final Landform (MLA 50254) Elimatta Project

67 Rehabilitation Methodology The rehabilitation methodologies described below have been designed to meet the rehabilitation goals, indicators and objectives described in Table The methodologies will be subject to change during mine life with: New information learnt from trials and experience; and New technology and research becoming available Contouring The preparation of disturbed areas prior to the establishment of vegetation will involve surface contouring to minimise erosion and maximise water retention. Recreated landforms will be contoured to resemble the original local topography with spoil dumps shaped to resembles low hills Ripping Following contouring, ripping of the surface will be carried out. The design criteria for ripping operations are detailed in Table The spacing between rip lines is determined by the slope of the land, which acts to reduce soil erosion and increase plant establishment rates. Where soils are particularly compacted, a more suitable ripping depth of 300 mm or more would be employed. Table 5.37 Design of Ripping Operations for Post-disturbance Surface Preparation Slope Minimum Ripping Depth Tyne Spacing Topsoil Spreading >10% 200 mm <1.5 m 5 10% 200 mm <2.5 m <5% 200 mm <5 m *Soils which are severely compacted are to be ripped to a depth of 300mm or greater. The surface of post-disturbance rehabilitation sites will be topsoiled to a depth of 300 mm where suitable quantities of topsoil are available, and erosion control structures constructed where they are required Revegetation Areas to be rehabilitated will be seeded with appropriate plant species, which are known to occur in the local area. Species selection will aim to achieve the domain specific rehabilitation goals and objectives in Table Habitat-matching of species will be undertaken for each mine domain to ensure the best chance of rehabilitation success. Where appropriate to the proposed land use, native species endemic to the area will be used in the rehabilitation works on-site. In particular, species which will encourage the return of native fauna, such as nectar producing species, will be used. Examples of appropriate tree species for rehabilitation include Eucalyptus tereticornis, Acacia harpophylla and Eucalyptus populnea. Elimatta Project

68 Domain Specific Rehabilitation Techniques The following sections provide domain specific rehabilitation strategies for the Elimatta Project. The strategies presented below aim to achieve the rehabilitation goals and objects described in Table Final Voids The final void will be left in a safe condition by constructing a safety bund wall around each void from competent rock and/or fencing, depending on the terrain, to limit human and animal access. The safety bund wall will be constructed as described in Technical Guidelines for the Environmental Management of Exploration and Mining in Queensland. This guideline states that the bund wall should be of a minimum height of 2 m, with a minimum base width of 4 m and be located at least 10 m beyond the area potentially affected by any instability of the pit edge. To ensure the safety of the final void, the surrounding final slopes should be such as to minimise the risk of slope failure. This will be assessed by a suitably qualified geotechnical engineer. The following will be considered when assessing the geotechnical stability of high walls: Long term final void water levels; Height and inclination of slope and number and spacing of intermediate benches (as may be required to achieve the final slope); Shear strength of the highwall soils and rock; and Density and orientation of fractures, faults, bedding planes, and any other discontinuities, and the strength along them. The control of surface inflow into the final void is essential for the long term management of water quality within the void and will also aid in the control of erosion to low walls and high walls. Surface water flow can cause slope deterioration and ultimate failure. Drainage will be directed away from the highwall face through the construction of interceptor channels / drains around the perimeter of the highwall. These control measures will restrict the water directly entering the void to surface runoff from rehabilitated areas as well as rainfall. Surface water entering the void will be controlled through the surface water management system. In-Pit TSF (TDP) Modelling suggests that TDP will become almost completely filled with tailings by the end of the mine life and could be covered with a soil cover for rehabilitation. However, if the tailings fill occurs to a level lower than the surrounding ground level, it is possible that TDP will subsequently become a residual void in which case it will be managed as such. A separation layer over the exposed tailings surface will be required. This cover will form a capillary break over the underlying tailing surface. It is proposed that the cover will likely need to be placed by hydraulic means. However, it may be possible to end-dump spoil into wet, uncrusted in-pit tailings. It is anticipated that the in-pit tailings will undergo more limited consolidation than the tailings in the surface TSFs; as TDP will be filled at a higher rate of rise. Hence, the in-pit tailings will be unlikely to achieve sufficient shear strength to allow a cover to be placed by trucks and dozers, even if a geotextile and geogrid could first be placed as separation and reinforcing layers, respectively. Final confirmation of Elimatta Project

69 the method of cover placement will depend on the bearing capacity of the tailings at the time of rehabilitation. Water will first be drained from the tailings surface to facilitate cover placement, and to facilitate drainage of the cover itself following hydraulic placement to maximise the strength gain in the tailings. Hydraulic placement of the cover will be achieved using a dedicated, small-scale, mobile pumping plant, mounted on a skid to allow it to be moved around the perimeter of TDP. Cover placement will commence from the perimeter of the tailings, the cover will be built-up locally to about 2 m depth, and the discharge pipeline will be progressively extended out over the trafficable cover already placed, to complete the cover. This technique was successfully demonstrated at Red Dome Gold Mine in North Queensland for placing a cover of coarse-grained fill over previously-submerged, soft, in-pit tailings. The cover material will be durable (that is, non-slaking), well-graded including coarse particles up to about 50 mm in size, and non-sodic so as to support vegetation if required, and not erode. Suitable fill for cover purposes will be stored within and sourced from the spoil excavated during mining. Selected spoil will be stockpiled during mining as close to the TSF as practicable for later use as cover material. It is expected that the volume of cover required during rehabilitation of the TDP will be provided from the expansive spoil reserve mined over the 32 year mine life. Over 1 billion bcm of spoil is expected to be excavated and stockpiled during the course of operations. The proposed excavated waste management strategies will assist in identifying the distribution and extent of sodic and dispersive materials. Gradual covering, by hydraulic means, of the tailings deposited in TDP will promote drainage, consolidation and strengthening of the loaded tailings. This will allow the build-up of a 2 m thickness of fill to form a cover, with sufficient bearing capacity to make the surface trafficable for low bearing pressure equipment such as a D6 swamp dozer. The feasibility of this has been demonstrated at Coppabella Mine in Central Queensland, where the upper, coarse-grained, co-disposal beach was successfully developed to a thickness of only 0.5 m on segregated fines, providing adequate bearing capacity for a small scale machinery up to approximately 4 tonnes GVM. Figure 5.30 shows a cross section of the rehabilitated final landform for the TDP. Figure 5.30 TDP Final Landform Design Based on a review of the rates of rainfall and evaporation in the region, and the likely profile of the landform, it is considered feasible that a water body with stable water quality conditions can be maintained; consistent with typical residual void conditions. The control of surface inflow into the final void is essential for the long term management of water quality within the void and will also aid in the control of erosion to exposed low walls and high walls. As with the other residual voids, surface water inflow into TDP will be restricted through the use of control measures such as bunds and interceptor drains so as to limit the extent of watershed which reports to the void. Elimatta Project

70 Exploration Areas Where exploration disturbances are to be temporarily rehabilitated, due to the potential for future disturbance, the following will occur: Capping the drill hole; and Removal of all sample bags and rubbish. When permanent rehabilitation is required (no potential for future disturbance) exploration drill holes will be permanently plugged. This requires cutting the PVC collar off at ground level and plugging the hole with a concrete plug. Soil is then mounded over the concrete plug so that the plugged area sheds water. The following rehabilitation activities of the exploration drill pad will also occur: A drying out period to allow water to evaporate from the drilling muds in the sumps; Backfilling of drilling sumps; and Scarifying the surface. Should natural regeneration not be successful after the first year, seed from species native to the area will be sown before the following wet season to enhance revegetation Infrastructure Areas Prior to rehabilitation and decommissioning all project related infrastructure, future uses for the infrastructure will be assessed in consultation with all relevant stakeholders as benefits may be identified. All infrastructures will be removed unless formal written agreements have been reached with the post-mining landowners/managers for its ongoing use, maintenance, and management. Where agreements have not been reached to retain infrastructure and buildings they will be removed from site in an acceptable and suitable manner. Rehabilitation of infrastructure areas will aim to return the land to its pre-mining land use in accordance with the goals and objectives described in Table Buildings In the absence of a continuing use for the project buildings post relinquishment of the mining leases, all buildings and infrastructure (including footings and foundations) will be demolished and removed from the site. All recoverable scrap steel will be sold and recycled, with the remaining non-recyclable wastes disposed of to an authorised landfill. Prior to disposal, all wastes will be assessed and classified in accordance with the Environmental Protection (Waste Management) Regulation A Land Contamination Assessment will be undertaken on all building sites. Contaminated materials will be excavated and disposed of to an appropriately licensed facility. Rehabilitation in areas from which buildings and other infrastructure are removed will be ripped, recontoured and revegetated. Roads Roads that are not required post project completion will be reshaped, topsoiled, and ripped and seeded. An appropriate fertiliser will be applied if required. Elimatta Project

71 Workshops, Chemical and Fuel Storages All workshops, chemical and fuel infrastructure will be removed from site on the completion of the mine life and sold, recycled or appropriately disposed of to a facility authorised to accept such waste. A Land Contamination Assessment will be undertaken on all workshops and chemical/fuel storages. Contaminated materials will be excavated and disposed of to an appropriately licensed facility. Following removal of infrastructure, land will be ripped, re-contoured and revegetated. CHPP The rehabilitation of the CHPP will consider the same decommissioning and rehabilitation process as the workshops and chemical/fuel storages. Once the infrastructure has been removed, a Land Contamination Assessment will be undertaken. Any contaminated material will be removed and disposed of to an appropriately licensed facility. Following removal of infrastructure, land will be ripped, re-contoured and revegetated. Powerlines Rehabilitation of powerlines and other associated electrical infrastructure includes dismantling and removal from site by a suitably qualified person. It is likely that power infrastructure may be retained on site as beneficial infrastructure for use by future landholders through agreements with local government and relevant power companies. Water Supply Pipelines There are three options associated with the decommissioning of the water supply pipelines: Abandonment where the pipeline is purged, physically disconnected from the point of supply, and sealed at both ends; Removal where the pipeline is purged from removed from its easement in entirety; or Beneficial re-use where sale or donation to a third party occurs which sees the pipelines continue to be beneficially used. International best practice recognises that removal of the pipeline from the easement is rarely a commercially or environmentally viable option for decommissioning. Therefore, it is likely that these pipelines will either be abandoned or re-used by a third party Waste Disposal Spoil Dumps Mine spoil and coarse rejects from the CHPP will be disposed of in both out-of-pit and in-pit spoil dumps. Spoil dumps will be progressively rehabilitated over the life for the mine, and rehabilitation will commence as soon as possible, within two years, of the land becoming available. Progressive rehabilitation will function to reduce erosion potential and improve the water quality runoff from overburden stockpiles. Elimatta Project

72 Waste characterisation indicates Elimatta overburden/interburden, floor, washery waste and coal materials are unlikely to be acid producing or release significant salinity or metals/metalloids, and will not require special handling for ARD or neutral drainage control (EGI 2012). Initial sodicity testing indicates that some overburden/interburden materials are likely to be sodic and dispersive, and may be subject to surface crusting and high erosion rates if placed in the surface of dumps and exposed directly to rainfall (EGI 2012). Placement of spoil with known sodic/dispersion potential will preferentially avoid dump surface areas. Dump surface materials may be treated (with gypsum or lime) if erosion cannot otherwise be controlled. Spoil dumps above the natural surface will be re-contoured to achieve a maximum slope of 1V:6H. This outer slope geometry and surface treatment will ensure adequate geotechnical stability and safe accessibility, while minimising the catchment and erosion potential of the slope. The final landform has been designed to be water shedding to minimise water infiltration. Rock lined drains will be installed, where required, to manage surface runoff and prevent erosion. The slopes and top of the spoil dumps will be topsoiled and deep ripped to bind the material. Local plant species and an appropriate fertiliser, if required, will be directly applied onto the topsoiled surface to meet the rehabilitation goals and objectives described in Table The proposed final landform of the Elimatta Project is shown in Figure 5.28 and Figure A cross section of the final landform of a typical Elimatta spoil dump is shown in Figure Figure 5.31 Typical Waste Dump Final Landform Profile Surface TSFs (TDN and TDNA) Outer Slopes of Containment Walls The two surface TSF containment walls will be limited to a maximum height of 16 m. To ensure an adequate factor of safety (>1.5) against geotechnical instability in the long-term, it is anticipated that these relatively modest containment walls will likely require an outer slope angle of the order of 1(V) in 3(H), constructed as a single slope (without contour banks or down slope drains). Contour banks and down slope drains are not found in nature and are at best temporary structures; contour banks being prone to piping and overtopping failure, and downslope drains having the potential to be bypassed or undercut. The surface treatment of the outer slopes will involve the placement of a rocky soil cover. The rock content will provide erosion protection while the soil content will facilitate moisture retention to support and maintain native vegetation to form a corridor for native fauna, and provide visual amenity. This outer slope geometry and surface treatment will ensure adequate geotechnical stability and safe accessibility, while minimising the catchment and erosion potential of the slope. Excess rainfall runoff from the remediated tops of the surface TSFs will be directed to purpose-built drain structures and not Elimatta Project

73 be directed over the TSF outer slopes, to avoid the concentration of rainfall runoff and the heightened potential for erosion that would result. Rehabilitation of Tailings Surface Rehabilitation will involve the placement of a cover to allow revegetation and achieve the agreed postmining land use. The more geotechnically stable the washery wastes and the cover over them, the greater the potential for re-use. The geotechnical stability of the washery wastes and the placement of a cover are facilitated by dewatering, desiccation and strengthening of the full depth of the deposit. It is anticipated that the tailings stored in the surface TSFs will undergo consolidation and desiccation for many years before rehabilitation is required, which is expected to achieve sufficient shear strength to allow cover placement using trucks and dozers. To ensure this, surface water will be drained from the surface to facilitate consolidation and desiccation. Prior to cover placement being attempted, the (peak and remoulded) shear strength profile with depth of the consolidated and desiccated tailings will be assessed by vane shear strength testing. An average vane shear strength of at least 30 kpa (allowing for a low bearing pressure D6 swamp dozer (<35 kpa) and the weight of placed cover material) will be required over the upper 2 m depth of the tailings to ensure that a cover about 2 m thick can be safely placed. The cover material will be durable (that is, non-slaking), well-graded including coarse particles up to about 50 mm in size, and non-sodic so as to not inhibit rooting by subsequent vegetation. Suitable material for cover purposes will be stored within and sourced from the spoil excavated during mining. Weathered sandstone spoil is preferred and will be stockpiled during mining for later use as cover fill. Topsoil will be spread to a nominal 150 mm thickness to support subsequent vegetation. Once required for rehabilitation, the cover material will be dumped by trucks along the perimeter of the stored tailings, and left for about two weeks to allow the tailings to drain, consolidate and strengthen under its weight. The fill will then be pushed over the tailings along a broad front to a height of about 1 m using a low bearing pressure D6 swamp dozer, ensuring that bow wave failures are not generated in the tailings at the leading edge (which would signify that the peak shear strength of the tailings had been exceeded and that they were remoulding). Further fill will then be dumped by trucks along the perimeter of the stored tailings, and left for about two weeks to again allow the tailings to drain, consolidate and strengthen under its weight, before being pushed over the completed 1 m lift, and beyond it to a height of about 1 m. This process will continue progressively until the entire tailings surface is covered by about 2 m of fill. Once covered by 2 m of fill, the shear strength of the consolidated, desiccated and loaded tailings will rise further, sufficient to support a post-mining grazing or native habitat land-use. Once the placed cover material has largely ceased settling, indicating that the underlying tailings have consolidated under its weight, the completed surface will be contoured to drain gently (at nominal slopes of about 1%) towards the location of the spillway, and then covered with a nominal 150 mm of topsoil and seeded to suit the post-mining land-use, in accordance with the goals and objectives of Table Significant drainage channels across the covered tailings will be sheeted with coarse rock for erosion protection. It is expected that the volume of cover required during rehabilitation of the surface TSFs will be provided from the expansive spoil reserve mined over the 32 year mine life. Over 1 billion bcm of spoil is expected to be excavated and stockpiled during the course of operations. The proposed excavated waste management strategies will assist in identifying the distribution and extent of sodic and dispersive materials. Elimatta Project

74 Figure 5.32 shows a cross section of the rehabilitated final landform of a typical surface TSF at Elimatta. Figure 5.32 Surface TSF Final Landform Design Removal of Rainfall Runoff It is desirable to not allow excess rainfall runoff to pond on remediated TSFs. Ponding has the potential to increase the net percolation into the underlying tailings, thereby increasing the risk of contaminated seepage into the environment. Excess rainfall runoff from the remediated tops of the TSFs will be directed to purpose-built spillway structures constructed in natural ground and directed to the undisturbed streams. The spillways will be lined with rip rap or other suitable treatments to protect them against erosion. A sediment pond will be constructed on the covered tailings just upstream of the spillway to limit the discharge of sediment Water Dams Water management dams that contained potentially contaminated water during mining will be drained, or allowed to evaporate. Contaminated material will be either removed from site or covered with benign rock material. A Land Contamination Assessment will be undertaken on all hazardous dam sites. Stormwater dams will be re-contoured and original drainage paths restored where possible. The surface soils will then be ripped, topsoiled and revegetated Diversions By Year six of Elimatta Mine operations, Horse Creek will have been diverted to its final position and mining operations will not impact on the creek route any further. The alignment of the final diversion will be in operation in excess of 25 years prior to mine closure. As a result, ample opportunity is available to monitor the performance of the channel development. At mine closure, the diversion will not require further maintenance. As diversions will be both temporary and permanent, revegetation objectives and strategies have been tailored to meet the operational requirements of each stage of the diversion. Temporary Diversion Due to the short lifespan of temporary diversions and the fact that they will be excavated as mining progresses, revegetation objectives will focus on maintaining structural integrity of the diversions and minimising downstream impacts. This includes maintaining a stable landform, providing adequate groundcover to minimise erosion and sedimentation, minimising the spread of weeds and minimising impacts on water quality. Elimatta Project