Stormwater run-off needs to avoid flooding, erosion and pollution of water bodies within a catchment. Stormwater systems should control stormwater flow and remove waterborne pollutants from urban run-off prior to their discharge into receiving waters.
If stormwater disposal is managed in a sustainable manner, the impact on the environment is less and longer-term maintenance costs are reduced. Stormwater management can provide attractive amenity features within and adjoining subdivisions.
The extent of impermeable paved surfaces should be controlled to reduce the stormwater run-off. Historically local roads are unnecessarily wide. Using narrower carriageways and semi-permeable paving for on-road parking can help to reduce the area of impermeable surface. Use swales and wide grass berms to allow groundwater recharge, slow the movement of water, and reduce pollutants into receiving water bodies.
DS-1.20.1 Design Elements
The following shall be considered during the design process:
- Ensure that post-development flows are restricted to pre-development levels using a variety of ‘treatment train’ stormwater methods within lots and throughout the drainage network.
- Reduce stormwater discharge to reticulated networks by the use of street edge swales and rain gardens to collect stormwater run-off from paved surfaces.
- Improve the quality of stormwater reaching streams by creating water flow paths through planted areas such as grass berms, swales and constructed wetlands.
- Consult an engineer as to the most appropriate solution in regards to the site’s topography, soil types and ability to dispose of stormwater through groundwater recharge and soakage.
- Encourage the detention and re-use of stormwater within each lot. Rainwater collection from roofs can significantly reduce the amount of stormwater discharged during storm events.
- Encourage single car-width driveways and vehicle crossings, to reduce impervious surfaces.
- Design wetlands and ponds to avoid water quality problems. Select vegetation to avoid choking choke waterways.
- Use permeable hard surfaces wherever possible.
Definitions in this section