National Wildfire Coordinating Group

Ash Pit Hazards


Ash pits are an inherent and hidden risk to wildland firefighters that can cause severe burns and injuries. Ash pits are created when a ground fire consumes underground fuels creating an empty space that is imperceptible from the surface.

Environmental factors that increase the risk of ash pit formation after a wildfire:

  • Extensive root systems of trees and shrubs.
  • Deep duff or peat, which is the organic layer covering mineral soil.
  • Landscapes that have once been cultivated or manipulated by heavy equipment, old dozer piles, sawmills, timber sale yards, or decking areas.
  • Animal dwellings that have become filled with decadent combustible debris.
    • Small rodent holes,
    • Beaver holes near dams and stream beds, or
    • Badger and coyote dens.
  • White ash is sometimes an indicator of ash pits, as are swarms of hovering insects.
  • With the sun behind the suspected ash pit, look for small nearly translucent smokes that dissipate quickly above the ground.
  • Ash pits often give off the smell of incomplete combustion or of creosote burning.

Mitigation measures to consider:

  • Identification of high-risk landscape.
  • Identify and flag all hazardous discovered ash pits.


Misc Fireline Hazards
Page Last Modified / Reviewed: 
Aug 2023

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