Macmahon–Manuka Wonawinta restart: design and risk notes for mine planners
Reviewed by Tom Sullivan
First reported on International Mining – News
30 Second Briefing
Macmahon Holdings has signed a Letter of Intent with Manuka Resources to restart open-pit mining at the Wonawinta silver project in the Cobar Basin, central west New South Wales, with production targeted from May 2026. The agreement positions Macmahon as preferred mining contractor for the brownfield operation, which previously focused on shallow oxide silver ore and existing heap leach infrastructure. Geotechnical and mine planning teams will need to update pit designs, wall stability assessments and water management for re-entry into partially rehabilitated pits and legacy waste dumps.
Technical Brief
- New South Wales jurisdiction brings compliance with state-specific mine safety, rehabilitation and environmental licensing conditions.
- Cobar Basin setting suggests logistical reliance on established regional mining supply chains and workforce pools.
- Similar brownfield restarts often leverage existing power, water and access roads to compress pre-production capex.
Our Take
Within our 103 silver-tagged pieces, most Australian coverage has centred on new builds or exploration rather than restarts, so the Wonawinta silver project signals a maturing phase where previously mothballed assets in New South Wales are being brought back into the supply mix.
A May 2026 restart at the Wonawinta mine in the Cobar Basin gives Macmahon Holdings Limited medium-term work visibility beyond typical three-year contract horizons seen in many of our Australian Mining items, which can support fleet planning and labour retention in central west New South Wales.
For Manuka Resources Limited, locking in a mining contractor ahead of the Wonawinta silver project restart reduces execution risk in a region where skilled operators are in demand across multiple New South Wales projects in our database, potentially improving bankability for any associated funding processes.
Prepared by collating external sources, AI-assisted tools, and Geomechanics.io’s proprietary mining database, then reviewed for technical accuracy & edited by our geotechnical team.
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