Closure and Rehabilitation Strategy for Ravensworth Voids 4 and 5
ATC Williams (ATCW) has supported ash management and rehabilitation planning at Bayswater Power Station since 2020, delivering ash reconciliation, storage capacity assessments, geotechnical investigations, landform design and long-term rehabilitation strategies.
As part of the planned closure of the power station in 2033, AGL Macquarie engaged ATCW to develop a practical, cost-effective strategy for rehabilitating Ravensworth Void 4 and Void 5 (RWV4 and RWV5), approximately 14 km from the station in the Hunter Valley, New South Wales. The voids form a critical part of the station’s ash management system and must be rehabilitated in accordance with Mining Lease 1349.
RWV5 currently serves as the primary fly ash disposal facility, with hydraulic fly ash transported through a 14 km carbon steel pipeline from the Ravensworth Ash Plant (RAP). RWV4 functions as a water storage facility supporting ash placement operations.
ATCW set out to deliver a technically robust rehabilitation strategy that maximised beneficial reuse of existing ash materials, minimised rehabilitation costs and produced stable, free-draining final landforms meeting long-term regulatory requirements.
The project presented five significant engineering and operational challenges:
During 2025, ATCW ran a comprehensive closure optioneering and modelling assessment to evaluate and optimise AGL Macquarie’s proposed rehabilitation strategy for RWV4 and RWV5. The assessment considered future ash generation, material availability, transport logistics, void storage capacity, settlement behaviour, closure sequencing, operational constraints and long-term rehabilitation objectives.
The assessment evaluated how AGL’s proposed ash management and material transport strategy could be optimised to maximise beneficial reuse of available ash, minimise imported fill requirements and achieve the required final rehabilitation landforms. The resulting closure strategy comprised:
ATCW’s assessment demonstrated how these material streams and placement methods could be coordinated to achieve the required rehabilitation landforms while maximising the use of existing by-product materials and minimising reliance on imported fill.
ATCW supported the strategy through geotechnical investigations, laboratory testing, ash characterisation, density reconciliation, consolidation testing and long-term settlement modelling. This work established the engineering properties of fly ash and bottom ash and confirmed their suitability for the final rehabilitation landforms.
Long-term consolidation and settlement modelling predicted post-closure performance, confirming that the rehabilitated landform will remain stable and retain its drainage function throughout the closure period.
AGL Macquarie has a practical, economically efficient roadmap for progressive rehabilitation of RWV4 and RWV5, leading to the planned closure of Bayswater Power Station in 2033.
By integrating ash management, geotechnical engineering and closure planning, ATCW delivered a solution that maximises beneficial reuse of existing ash, significantly reduces reliance on imported fill and supports long-term regulatory compliance.
The strategy produces a stable, free-draining final landform while reducing rehabilitation costs and advancing the site’s transition towards successful mine closure.
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