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Auckland Council

Soil erosion, sediment and dust from earthworks

Horonga whenua, para whenua me te puehu

Earthworks can result in erosion of exposed surfaces, which produces sediment and dust. This can then pollute streams, lakes and harbours, and kill both freshwater and marine vegetation and animals.

Increased risk of soil erosion

The risk of erosion increases if land:

  • has little vegetation on it
  • is steep
  • is on the bank of a river or lake
  • is disturbed
  • has erosion-prone geology (for example mudstone or pumice)
  • is under pressure from high stock density or machinery
  • is in an area of high and intensive rainfall.

How to control soil erosion

You can reduce the harmful effects associated with sedimentation by controlling erosion.

This can be done by incorporating appropriate erosion and sediment controls as an integral part of your project. This will include:

  • minimising areas to be disturbed
  • staging earthworks by undertaking earthworks in small areas over time
  • stabilising exposed areas quickly and keeping as much existing vegetation as possible, especially on steep slopes or areas close to watercourses
  • using appropriately designed sediment devices to retain and treat sediment before its discharged.

Both the landowner and contractor doing the earthworks need to be aware of the importance of erosion and sediment controls on their site.

For more information on how to manage erosion and sedimentation, see building site management.