Silt fences and sediment ponds

This page explains the expectations for creating silt fences, sediment ponds and/or silt socks that are required on most sites.

Install sediment control before starting earthworks

Before doing any earthworks on your site, including scrapping and vegetation clearance, and notwithstanding whether the amount of earthworks that you are undertaking requires resource consent or not, there will likely be a need for specific physical sediment control measures to be installed, to stop sediment laden stormwater leaving your site.

The following sequence of photographs show the most common and appropriate forms of sediment control measures used in Porirua City.

These items slow down stormwater flows coming off exposed earth surfaces and trap the sediment on the site.

Silt Fences

Silt fences are the most effective form of sediment control.

Photo showing an example of a silt fence.
The photo above shows an example of a silt fence trapping sediment in lowest corner of the site.

Sediment ponds

Sediment ponds are appropriate if there is one clear lowest corner of the site.

Photo showing a sediment pond.
The photo above shows a sediment pond in use located at the lowest corner of the site with an outlet pipe discharging clean water onto grass. 

Silt Socks

Silt socks are more appropriate when there are little exposed surfaces on building sites.

Photo showing use of a silt sock.
The photo above shows how silt socks can be used to trap sediment on building sites.

Maintain sediment control measures until yards are stable

Once these items are installed on the site, they must be maintained until such time when the site is stable and there is no longer a risk of sediment leaving the site.

Please ensure that all contractors working on the building site know what these items are, their purpose, and that they must stay in place (for example ponds are not filled in, silk socks are not moved to allow vehicle entry to the site).

Report sediment control problems to Council

If you see examples of sediment laden stormwater leaving a building site (or any sites), please take photos of these and e-mail them to  for the attention of the Resource Consents team, and the Council will investigate.