Decision IntelVale S.A.
Vale Brumadinho Dam Collapse
Estimated impact: $7B in settlements and remediation; 270 deaths
A tailings dam at Vale's Córrego do Feijão iron ore mine in Brumadinho, Brazil, collapsed without warning, releasing 12 million cubic meters of toxic mud. 270 people were killed, including many mine employees eating lunch in the path of the flow. The dam had been certified as stable just months before.
Decision context
Whether Vale's upstream dam construction method and internal stability monitoring were adequate, given that a similar Vale-linked dam (Samarco) had collapsed just three years earlier.
What the company’s own filing already carried
Not our reading of a memo. Vale S.A.'s own 20-F, filed 2018-04-13 (9 months before the 2019 decision), was read by the audit engine's deterministic structural layer: the same detectors that run on every audit, with no language model involved. Everything below is drawn from the company's own disclosure, before any knowledge of what followed, and never from the decision itself.
Would not absorb the hit: if the flagged risk fires, nothing disclosed in the structure would materially absorb that loss.
- Commodity-price-linked cash flowsunprotected
- This reads the company's own 20-F (filed 9 months before the decision), not the decision memo itself, so it can only understate what a full audit of the memo would surface.
- It reads the structure of the situation, not the trigger: whether a shock to the flagged conditions would be absorbed, never that a shock arrives.
- A reading of a dated filing, not a prediction: every condition can be checked against the company's own 20-F.
Decision anatomy
Red = risk factor present · Green = protective factor present
Biases present in the decision
★ Primary driver · Severity estimated from bias type and decision outcome
Toxic combinations
The curated library this case sits in
Across all 155 curated case studies in our library, by documented outcome:
The library is curated toward documented failures, so this split describes the library, not the base rate of deals. The case above is one row in it.
Lessons learned
- Confirmation bias: stability certificates were obtained from auditors who used the data provided by Vale rather than independent monitoring
- The Samarco disaster (2015) should have been a direct warning, but Vale treated it as an isolated event rather than a systemic risk indicator
- Placing employee facilities directly downstream of a tailings dam reflects a fundamental failure to internalize catastrophic risk
Source: Brazilian Federal Police investigation report (2020); Brazilian Senate CPI inquiry (2019) (Post Mortem)
These patterns were flaggable in Vale S.A.'s own record — before the outcome.
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Workflows that fire on decisions like Vale S.A.’s
The same Recognition-Rigor Framework that documents this case audits memos in the same shape — before the outcome forces the lesson.