Heavy Rainfall Can Put Impoundments at Risk, MSHA Warns

SOURCE: MSHA | October 15, 2025

Arlington, VA — Miners and mine operators should visually inspect impoundments thoroughly soon after significant rain and snowfall, the Mine Safety and Health Administration says in a new safety alert.

The agency calls the structures – used to confine waste, store water for mine use, control runoff and prevent flooding – an “integral part of mining.” It warns that “heavy rainfall and flooding across mining regions can increase the risk of impoundment instability and potential failures.” Causes include a loss of structural integrity as a result of saturated embankments and foundations, as well as blocked or overwhelmed spillways that increase the risk of overtopping.

In addition, inadequate inspections after weather events may delay the verification of possible hazards, while erosion or seepage along slopes and embankments may go unnoticed.

To help ensure the safety of impoundment structures, MSHA recommends:

  • Documenting and photographing all findings – including signs of erosion, seepage, cracking or settlement – and correcting any deficiencies promptly.
  • Ensuring spillways, drains and emergency overflow channels are clear and functioning.
  • Evaluating freeboard levels and adjusting water management practices as needed.
  • Notifying appropriate workers and MSHA about hazards.
  • Maintaining qualified, onsite or on-call workers for impoundment inspection and response.
  • Updating your emergency action plan and reviewing it with all workers.

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