Evolution Mining (Evolution) is the owner and operator of Mungari Operations (Mungari), located 600 km east of Perth and 20 km west of Kalgoorlie in Western Australia. Mungari is an established mine site with all major infrastructure in place. In September 2023, Evolution approved a capital investment of $250 million for the Mungari processing plant expansion, increasing its capacity from 2 million tonnes (Mt) to 4.2 Mt/a (per annum) (Evolution Mining Limited, 2023). The brownfield expansion of the processing facility maximises the use of the existing plant, with significant additions including the front-end crushing and milling circuits, installation of a larger gravity circuit and an expanded leach circuit. This case study focuses less on the design and construction of the plant expansion and instead details the activities undertaken by the Operational Readiness team that were critical to the project’s overall success. The paper also highlights key recommendations and lessons learned. Throughout the paper, the authors aim to impart knowledge and experience to the reader, rather than provide an exhaustive plan, and to offer key insights and recommendations for mineral processing professionals seeking to implement operational readiness plans at their sites. In summary, the case study demonstrates that success in any Operational Readiness team largely depends on ensuring the right people are in the right roles and have access to the required processes, training, tools, consumables, and other resources to commission the plant and maintain long-term operations safely.