Erosion and sediment control

Stormwater runoff

Stormwater run-off from construction sites has a high potential to cause water contamination and/or environmental harm. Under the Environmental Protection Act 1994 (EP Act) it is an offence to unlawfully deposit a prescribed water contaminant in or in such a way where it could reasonable enter a roadside gutter or stormwater drain.

Prescribed water contaminants include cement, concrete, clay, sediment, stones and plaster, among other construction related materials.

It is the responsibility of all staff and contractors at construction sites to ensure appropriate measures are in place to prevent environmental harm and uphold the General Environmental Duty (GED) under section 319 of the Environmental Protection Act.

WATCH THE SHORT VIDEO THAT EXPLAINS COMMON SOURCES OF POLLUTION ON CONSTRUCTION SITES

Soil cover is maximised, for example by:

clearing is limited to only the area necessary to undertake building work.
clearing of existing soil cover only occurs immediately before building work starts.
areas of bare soil not being actively worked are covered as soon as possible with a temporary covering that can be walked on during the building stage (e.g. spray-on soil binders, mulch (gravel, straw, wood) or that can be easily removed and replaced each day (e.g. plastic sheeting or geo-textile).

You must ensure that stockpiles are protected, for example by:

Covering stockpiles when not in use.
Ensuring stockpiles are not placed on top of sediment barriers (e.g. sediment fences).
Ensuring stockpiles are not located in overland flow paths. If unavoidable, run-off is directed around the stockpile (not for sites less than 450m2).

Kerb to lot groundcover

You must ensure that:

Exposed soil between the lot boundary and the kerb been covered, for example with turf
Stockpiles fully contained within the lot (not on the verge) or in accordance with a footpath closure permit issued by the relevant local government.

Downpipes and stormwater diversion

If the roof is in place, all permanent or temporary downpipes must be connected to all gutter outlets to connect all roof water run-off to the underground stormwater system.

Where the site has an area of land upslope of greater than 1500m2, catch drains must be provided to divert upslope run-off around bare areas of the site and been implemented as follows:

catch drains are lined with geofabric, UV resistant plastic or turf.
catch drains are located within the building site.
catch drains discharge to the roadway or to a stormwater drain safely without causing erosion.

Site Entry Exit Areas

You must establish a formal stable entry/exit area, for example a rock-pad and check that implemented measures well maintained and appropriate to prevent run-off, by for example:

A rock-pad is at least 2m wide, when site constrains allow it.
Formal entry/exit point extends from the kerb to the building slab.
For lots with clayey soils, entry/exit point incorporates geofabric overlaid with 40-75mm diameter rock laid at least 150mm thick.
Formal entry/exit point is covered with an additional layer of 25-50mm diameter gravel within the verge to make it safe for pedestrians.
Formal entry/exit point includes a bund to direct upslope run-off to a sediment trap on the lot.
Formal entry/exit point has been replaced or refreshed if clogging of the material with sediment has occurred.

*It is important that the rock-pad extends to the building slab and also includes a bund. If these features are absent, then the rock-pad can easily become a conduit for run-off from bare soil on the site to pass between the gap in the sediment fences. Rock-pads frequently become clogged with soil so it is important that the rock is either refreshed or replaced when this occurs.

Stormwater inlet protection

For sites that fall away from the road to an internal stormwater inlet pit, the pit should be protected to prevent entry of coarse sediment into the pit, for example by covering and maintain the pit with a filter cloth and surrounding the pit with a sediment collection pit. The pit should be maintained in good working order.

All J&D Contracting contractors must ensure that erosion and drainage controls have been installed (e.g. soil cover and downpipes).

Coarse Sediment Barriers

Where required our sites may require a sediment barrier present to allow sediment to settle, for example by installing sediment fences downslope of all areas of bare soil in accordance with the following:

Is the sediment fence buried at least 200mm into the ground?
Are support posts provided at intervals no greater than 2m?
Does the sediment fence extend at least 450mm above ground level?
Are returns in the sediment fence provided?
If sediment fences are not installed, is the site less than 500m2 and less than 2 per cent slope and have alternate sediment barriers been provided?

Sediment fences are the most commonly used coarse sediment barrier. Sediment fences act like a small dam to slow the water to allow coarse sediment to settle out. It is therefore important that the sediment fence is buried into the ground, provided with supports and include returns to prevent water from flowing around the sides of the fence. Please note, sediment fences do not impede the movement of fine, clayey and silty material.

For smaller sites, alternative coarse sediment barriers such as mulch or rock berms, sediment socks, fibre rolls, or low sediment fences can be considered.

Cement, Plaster and Paint

Pollutants such as paint, plaster and cement must be prevented from entering the stormwater system, for example by:

washing equipment only in a contained area that cannot reach the stormwater system.
containing run-off when cutting materials with water-cooled saws.
ensuring cement-wash from exposed aggregate driveways is contained in a collection trench and residue is disposed of without release to the stormwater system.

Sediment is not the only pollutant generated on building sites. Water contaminants can also be created by activities such as washing equipment, cutting materials with water-cooled saws or exposing the aggregate in driveways. General waste and litter such as plastic or polystyrene packing may also be present on site. The contaminants created by these activities must also be managed and prevented from reaching the stormwater system.