Donlin mine tailings spill scenario: design and risk lessons for engineers
Reviewed by Tom Sullivan

First reported on MINING.com
30 Second Briefing
A new draft supplemental environmental impact statement from the US Army Corps of Engineers and BLM models a 27% tailings storage facility failure at NOVAGOLD’s proposed Donlin Gold mine in Alaska, warning a toxic wave could reach Crooked Creek village in 90 minutes, bury it in tailings and leave metal contamination in the Kuskokwim River basin for more than a century. The scenario, far larger than the previously assessed 0.5% spill, projects long-term erosion, groundwater mounding, altered stream channels and persistent reductions in fish abundance, with NGOs demanding analysis of a full dam failure. The 40-million-ounce, 2.22 g/t deposit is permitted for 1.1 million ounces per year over 27 years, but the SEIS outcome could modify, reaffirm or rescind the existing federal permit.
Technical Brief
- Draft SEIS models a partial TSF failure releasing approximately 27% of stored tailings volume.
- Failure scenario assumes a fast-moving tailings slurry “toxic wave” capable of human fatalities on impact.
- Hydrological modelling predicts inundation of thousands of acres, groundwater mounding and long-term alteration of stream channel morphology.
- Metal contaminants are projected to persist in soils and sediments for over 100 years, with wetlands potentially converting to uplands.
- Aquatic and riparian fauna, especially small-bodied species, face multi-decade habitat loss and generational population effects.
- Failure analysis remains limited to partial TSF breach; tribal and NGO stakeholders request explicit full-dam failure modelling.
- Monitoring and remediation concepts in the SEIS focus on dilution in the Kuskokwim River and long-duration cleanup to reduce impact magnitude.
- Safety commentary stresses that tailings dam failures are low-probability, high-consequence events requiring quantified flood depth and arrival-time predictions for effective evacuation planning.
Our Take
With Donlin Gold projected at 1.1–1.3 Moz/y over a 27‑year mine life, any tailings dam design in Alaska will be scrutinised as a long‑duration, high-consequence facility, especially in a Hazards context where our database shows relatively few gold projects of this production scale facing such explicit failure-modelling in public comment processes.
The US Army Corps of Engineers’ role here mirrors its involvement in Trilogy Metals’ Arctic project in Alaska, suggesting that Corps decisions on Donlin’s tailings and water management could inform expectations and precedent for other large-scale gold and base metals projects in the state.
Barrick Gold’s presence at Donlin alongside its other large gold assets flagged in our coverage (such as Nevada Gold Mines and Pueblo Viejo) means that any perceived tailings risk in Alaska could influence how investors benchmark Barrick’s group-wide ESG and dam safety profile against other major gold producers.
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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