The Federation Pb-Zn deposit, located approximately 15 km south of Nymagee, New South Wales, lies on the south-eastern margin of the Palaeozoic Cobar Basin. Discovered by Aurelia Metals Limited in 2019, the deposit was initially characterised in the feasibility study as an epigenetic, structurally controlled system, with massive sulfides hosted in steeply plunging, short-strike shoots surrounded by breccia zones. Subsequent infill drilling during the early stages of the mine development phase quickly led to a revision of the geological model. Within the broadly east-north-east-trending mineralisation envelope, the deposit hosts discrete, steeply dipping, high-grade lenses of massive sphalerite and galena, typically striking north-north-east. These lenses generally exhibit sharp contacts with the generally undeformed, barren siltstone host rocks, highlighting the importance of understanding the structural and stratigraphic controls. This revised understanding in orientation and orebody geometry prompted a change in both drilling strategy and grade control methods. Tightly spaced infill drilling, conducted in a new orientation from revised drill platforms to better define the short-strike lenses was implemented. Additional, detailed mapping and the introduction of face sampling was required to sufficiently define the economic zones for production. The implementation of rapid-turnaround grade control block modelling further supported efficient, reactive mine planning, effective stope design and minimised dilution between discrete ore zones. Unlike most Cobar-style deposits, Federation is distinguished by its overall east-north-east structural orientation and structurally controlled, narrow lens style. Mineralisation is hosted by gently folded, south-east-verging sedimentary host rocks. The structural control is evident, with mineralisation textures, tenor and structural measurements key to defining the individual lenses. The integration of geological reinterpretation using modern techniques with adaptive operational practices has been critical to reacting and optimising early-stage mine planning and maintaining the project development schedule.