Development Application Part 2 - Environmental & Stormwater Management Plans · OPW11/0335

                                                                    Poorly maintained or inappropriately located
                                                                    sediment fences can lead to sediment entering the
                                                                    stormwater drain

Well designed and maintained sediment fence




Grassed areas or grassed filter strips (narrow strips of turf) have generally not proven to be effective in the
capture of sediment from urban residential building sites. At best these areas should be used as a
secondary sediment barrier in partnership with a sediment fence. The main benefit of maintaining grass on
and around a building site is to help reduce soil erosion in the first place.

Grass filter strips are often placed adjacent to road kerbs and footpaths during the subdivision stage of a
new estate. All reasonable and practicable efforts should be taken to minimise damage to this or any
established grass in or around a building site.

Vegetated buffer zones
In rural residential areas, building sites are often surrounded by large areas of grassed or vegetated land.
Such land may be used as the primary sediment barrier if it:

•   is down-slope of the soil disturbance
•   is fully contained within the property
•   does not contain any drainage swales that may concentrate stormwater runoff
•   is at least 15 metres long (in the direction of flow)
•   contains established grass that fully covers the soil

The minimum recommended length (in the direction of flow) of a grassed buffer zone is:

                Slope of grassed buffer (%)                        Minimum length (metres)
                              0-3                                               15
                                4                                               20
                                5                                               25
                                10                                              50




Sediment controls for stormwater inlets located within the property may consist of geotextile fabric placed
either directly over the grated inlet or around the inlet supported by a timber frame.

Field inlet protection is necessary where these inlets drain areas of bare and unprotected soil.

During storms, pending should be allowed to occur around the stormwater inlet to assist in the settling-out of
sediments. A structurally sound support frame is needed to withstand the weight of sediment-laden water.

Ensure that the type of sediment barrier used does not divert sediment laden water elsewhere without being
treated by a sediment control device.