KSM gold-copper tunnels dispute: design and layout implications for mine planners
Reviewed by Tom Sullivan

First reported on MINING.com
30 Second Briefing
Tudor Gold has dropped its appeal of a British Columbia Chief Gold Commissioner ruling over Seabridge Gold’s Mitchell Treaty Tunnels (MTT), easing one legal obstacle to the C$6.4 billion KSM gold-copper project but leaving two BC court actions active. The dispute centres on about 12.5 km of Seabridge’s planned 22-km twin access tunnels, each roughly 5.9 m by 5.5 m, crossing Tudor’s Treaty Creek claims and, Tudor says, sterilising parts of the Goldstorm, Perfectstorm and CBS zones. Goldstorm alone hosts 912.3 million tonnes indicated at 0.85 g/t Au, 5.07 g/t Ag and 0.15% Cu, so tunnel buffer zones could materially constrain future underground layouts and access.
Technical Brief
- KSM’s capex is estimated at C$6.4 billion, framing the scale of the tunnel infrastructure decision.
- Seabridge’s Mitchell Treaty Tunnels are treated as “critical infrastructure” for KSM under the conditional mineral reserve.
- Tudor has two remaining BC court actions: one on the conditional mineral reserve scope, one judicial review of the licence of occupation.
- The conditional mineral reserve obliges current claimholders not to obstruct, endanger or interfere with tunnel construction and operation.
- Tudor’s January estimate for Goldstorm reports 24.9 Moz Au, 148.7 Moz Ag and 3.048 Blb Cu indicated.
- Inferred Goldstorm resources add a further 4 Moz Au, 18.6 Moz Ag and 327.7 Mlb Cu.
- Tudor now holds 80% of Treaty Creek after acquiring American Creek, consolidating control over the affected ground.
- A preliminary economic assessment on a higher‑grade underground start at Goldstorm is scheduled for Q3, informing future mine design around the tunnels.
Our Take
The Goldstorm deposit’s large, low-grade gold-copper-silver inventory at Treaty Creek positions Tudor among the bigger undeveloped gold stories in British Columbia’s Golden Triangle, but the 0.15–0.17% copper grades imply that long-term copper price assumptions and power costs will be critical to eventual project economics.
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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