Today’s Erosion and Sediment Control Tip: #2


In order to control erosion on a construction site, you must first understand the erosion process.

Rainfall and the surface runoff of rainfall produces four main types of erosion on a construction site:

  • Splash Erosion occurs when the raindrop impacts the bare soil surface and dislodges soil particles.
  • Sheet Erosion occurs either after the surface of the soil is saturated or the rainfall exceeds the infiltration rate of the soil. Then the soil detached by splash erosion and the additional soil particles detached by runoff/overland flow move downslope. (Note: Splash and Sheet are sometimes referred to as Interrill Erosion)
  • Rill Erosion occurs when the sheet flow concentrates and causes small rills (about 1 inch deep) further eroding the soil surface.
  • Gully Erosion occurs when runoff water in a rill detaches more soil and deepens and/or widens the channel to a significant size.  (Note: There is no universally recognized depth when a rill becomes a gully).

So, if we can control erosion, there is much less sediment to deal with on a construction site.  And the best way to control erosion is to stop the processes of Splash and Sheet (Interrill Erosion).

In order to do this we should always look for ways to:

  • Minimize the amount of bare soil exposed to the environment by:
    • Phasing the work, and
    • Limiting vegetation clearing.
  • Minimize the time that bare soil is exposed to the environment by:
    • Covering the surface of the bare soil, and
    • Vegetating each area as soon as the final surface is achieved.

When you minimize erosion, capturing sediment becomes easier.


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