The Flinders Power Partnership (FPP) business is comprised of three distinct operations, being the Leigh Creek Coalfield, the Leigh Creek Railway and the Augusta Power Stations. This document addresses the closure of the Leigh Creek Coalfield. The Coalfield is situated entirely within the area of four perpetual Crown Leases granted under the Electricity Trust of South Australia Act, 1946 (SA), being legislation of restricted application specifically authorising coal mining and ancillary operations at Leigh Creek. The Coalfield was mined by ETSA since the late 1940s until the four Perpetual Leases were transferred to Flinders Power Partnership under the Flinders Power Generation Business Sale Agreement and by virtue of ss14(8) and (9) of the Electricity Corporations (Restructuring and Disposal) Act 1999 with effect from 8 September 2000. In June 2015, the Alinta Energy Board announced the closure of the Flinders business, with Leigh Creek Coalfield mining ceasing in November 2015. Planning commenced in June 2015 to prepare for the cessation of operations including the preparation of this Mine Closure Plan. Coalfield operations are principally regulated by the Chief Inspector of Mines appointed under the Mines and Works Inspection Act 1920 (SA) (MWIA). This mine closure document is a development program applying to the Leigh Creek Coalfield, for purposes of Regulation 9 of the Mines and Works Inspection Regulations 2013 (SA). It replaces Approved Development Plans numbered AMDP 00/41 and AMDP 00/42 in so far as they relate to mine closure and mine rehabilitation of the Leigh Creek Coalfield. This document addresses environmental and social risks both in relation to the areas defined by the Perpetual Leases and to neighbouring landholders and communities. The environmental and social values that have been considered in preparing the plan in relation to the closure of the Coalfield include the: • Health and safety of people; • Sensitivity of associated ecosystems; • Maintenance of water quality and flows in surface waterways; • Maintenance of water quality in groundwater; and • Creation of safe, stable, non-polluting and sustainable landforms. Specifically, the principal closure objective is to prepare the Coalfield for transfer of control of the land back to the South Australian Government. FPP has developed this closure plan based on the management of existing and legacy material risks for distinct domains within the mine. Risks identified and associated mitigation plans primarily address public safety, pit wall stability, spontaneous combustion, retention dam integrity, surface water and ground water management, preservation of indigenous and non-indigenous heritage sites and items, and existing site infrastructure. Laboratory investigations undertaken by industry-leading spontaneous combustion experts B3 Mining have shown that: The carbonaceous overburden mudstones at Leigh Creek Mine do not have sufficient intrinsic reactivity to initiate and sustain self-heating to the point of combustion and require a heat source to elevate the rock temperature to a sufficiently high temperature for the organic carbon within the mudstone to sustain self-heating and reach thermal runaway. B3 Mining (2017) concluded that ‘fugitive coal from the mining operation has been mixed with the carbonaceous rocks and it is this coal that has initiated a hot spot, which has then elevated the temperature of the carbonaceous rocks to a point where they take over and the fuel load of the carbonaceous rocks is sufficient to continue self-heating to ignition’; and • The coal intrinsic reactivity decreases exponentially following exposure to air. Investigations have shown that after five years of exposure to air, the risk of self-heating to the point of combustion is negligible. These findings confirm site experience whereby spontaneous combustion is spatially random and limited to the most recent waste rock dumps. Instances of combustion have also substantially reduced since the cessation of mining in November 2015. The data has been used to develop a spatial understanding of spontaneous combustion propensity across the mine lease, and rehabilitation designs are targeted at those areas of higher risk. The key rehabilitation strategy to control the risk of spontaneous combustion to as low as is reasonably practicable is to re-profile waste dump slope angles in those areas of the mine of high potential and actual propensity, followed by applying cover of inert material. The act of re-profiling significantly reduces the ability of oxygen to permeate the dump, and the cut and fill methodology inherently reduces particle sizing of the outer overburden layer and provides a compacted surface. The subsequent application of the inert cover through further dozing also provides a further compacted seal. Physical and chemical testing of the nominated inert cover indicates that the material can be defined as ideal for spontaneous combustion control. Further, WEPP erosion modelling indicates that low levels of erosion will occur over time, providing comfort that the cover will provide a sufficient barrier to water and air infiltration over the interim period where residual coal within waste dumps continues to oxidise to the point of being a negligible risk of self-heating to the point of spontaneous combustion. The control of surface water is a critical element to ensure rill and gully erosion is limited, and provide protection to rehabilitated slopes. In developing closure plans, FPP has taken into account existing historical mine information, monitoring records and site experience. To ensure an optimal approach to closure and to utilise the best available guidance, closure planning has been informed by advice provided by expert independent consultants in relation to ongoing geotechnical stability, spontaneous combustion management, surface and ground water management, soil characterisation and site contamination. As a result, two major plans have been developed for closure, specifically: • The ‘Mine Rehabilitation Plan’ outlining bulk earthworks to implement mine rehabilitation designs; and • A ‘Schedule of Additional Works’ outlining the additional actions required as arising from the risk assessment process. FPP has consulted extensively with the South Australian Government Department of State Development (DSD), the Environment Protection Authority (EPA), Safework SA and the Department of Environment, Water and Natural Resources (DEWNR). In addition, a Stakeholder and Community Engagement Plan will be used to inform community engagement activities to ensure the right information is provided to the right people at the right time. A suite of monitoring tools has been developed to assess the effectiveness of the rehabilitation techniques in meeting closure objectives throughout the duration of the closure program. Progressive performance monitoring of closure activities against defined, measurable criteria is essential to ensure that: • Continued compliance under the Mines & Works Inspection Act, the Work Health and Safety Act and the Environmental Protection Act is maintained; • The program is completed to an agreed standard and timeframe; • There is demonstrable compliance against lease relinquishment obligations; and • Continuous improvement opportunities are identified and enacted. Routine assessment of progress against plan will be conducted internally and will be formally documented quarterly as part of the internal audit schedule. External assessment against the work plan will occur on a periodic or milestone basis with progress reported quarterly to DSD, EPA and SafeWork SA. While the monitoring throughout the closure program provides a window of opportunity to verify the effectiveness of controls, it is proposed that a period of Post-Completion Monitoring and Minor Works be undertaken, which will: • Reduce ongoing risks associated with public safety, including site access by authorised and unauthorised personnel by providing a degree of site presence; • Provide additional opportunities to verify the degree of success of the control program, particularly in relation to spontaneous combustion. Ongoing monitoring will increase the level of data and subsequent assurance. It will also provide opportunity for minor remedial works, if required; and • Provide a capacity to respond following heavy rainfall events. These opportunities will verify the success of the surface water controls adopted throughout the closure program and provide opportunity for minor remedial works, if required. Governance arrangements for the Post-Completion Monitoring and Minor Works period are yet to be determined, however the following options (or variations of them) may apply: • At the completion of the Works (being all the works under the plan other than the Post-Completion Monitoring and Minor Works) , FPP will enter a contract with a suitably qualified third party to deliver the requirements of the Post-Completion Monitoring and Minor Works scope to the extent of costs of $5m. FPP will continue to manage that contract and compliance with the Post-Completion Monitoring and Minor Works but will have a limit on its liability for the Post-Completion Monitoring and Minor Works of $5m and on the $5m of funding being transferred the Lease will automatically be relinquished; or At the completion of the Works, FPP will enter a contract with a suitably qualified third party to deliver the requirements of the Post-Completion Monitoring and Minor Works scope. At the time of completion of the Works (and satisfaction of the requirements set out below), the Lease will be relinquished and FPP will transfer the contract for the Post-Completion Monitoring and Minor Works to the SA Government together with the $5m of funds for the Post-Completion Monitoring and Minor Works; or • Lease transfer occurs to an interested party (subject to any SA Government approval required under the Lease). The interested party becomes responsible for the Monitoring and Minor Works commitments and FPP will transfer the amount of the $5m of funds for the Post-Completion Monitoring and Minor Works to the interested party; or • FPP transfers funding for the Post-Completion Monitoring and Minor Works to the SA Government as at completion of the Works. Subject to satisfaction of the requirements set out below the Lease is also relinquished. SA Government will then determine the most appropriate model to deliver the Post-Completion Monitoring and Minor Works scope. FPP considers that Lease relinquishment to SA Government will occur once the following conditions are met: • Lease relinquishment criteria (Appendix L) are complete; • The ‘schedule of additional works’ (Appendix BB) is complete; • Lease transfer criteria (Section 18 of the Mine Closure Plan) have been met; • EPA Licence obligations have been met (Appendix J), and the licence obligations are either terminated or transferred to a future party; and • A period of performance monitoring has been undertaken, being 1st January 2017 – 31st December 2018. FPP anticipates that all closure works will be complete, adequate performance monitoring will have been undertaken, and Lease relinquishment will occur, by 31st December 2018.