Central Tanami JV–Macmahon Groundrush decline: design and risk notes for mine planners
Reviewed by Tom Sullivan
First reported on International Mining – News
30 Second Briefing
Central Tanami Project Joint Venture has awarded Macmahon Underground a A$38 million contract to construct the Groundrush decline at the CTPJV gold mine site in the Northern Territory, Australia. The decline will provide new underground access beneath the existing Groundrush open pit, enabling future stoping and deeper resource development for JV owners Tanami Gold and MGX. For geotechnical and mine planners, the pact signals a shift from open pit to underground extraction, with associated requirements for decline ground support, ventilation and dewatering design.
Technical Brief
- Contract value is A$38 million, indicating a substantial early-capital allocation to underground access works.
- Macmahon Underground Pty Ltd, a Macmahon Holdings subsidiary, will execute the decline construction package.
- Scope is confined to the Groundrush decline at the CTPJV mine site.
- JV ownership split is between Tanami Gold and MGX, affecting capital funding and decision-making structures.
Our Take
The move from Macmahon Underground being named preferred contractor in April 2026 to a formal A$38 million decline agreement now indicates the Groundrush exploration decline has cleared key technical and commercial hurdles, which typically unlocks detailed mine design and early procurement for underground fleets.
MGX Resources’ previously flagged A$412.1 million funding pool for the Central Tanami Project suggests this decline package is a relatively modest but critical enabling work, implying further, larger surface and underground contracts in the Northern Territory are likely to follow if drilling and studies support a full-scale gold operation.
Within our Mining projects and contract award coverage, Macmahon’s repeat appearance at Central Tanami positions it as an incumbent underground specialist in the region, which can make it harder for rival contractors to displace them on subsequent stoping or development phases once the Groundrush decline is established.
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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