SCG 31131(SWM).RevA.pdf

5.0      STORMWATER QUALITY


In the absence of adequate controls, urban development can increase both stormwater runoff volumes
and peak discharge rates. In addition, this urban development has the potential for increased creek
erosion and the stressing of in-stream aquatic ecosystems. The use of stormwater detention or retention
systems aims at reducing these threats by limiting property flooding to acceptable levels and also
filtering stormwater runoff through a vegetated soils media layer, thus reducing the threats caused by
urban development. For the proposed development we have suggested to incorporate Water Sensitive
Urban Design (WSUD) principles in the landscaping for the proposed development to treat stormwater
before it exists the site. A series of vegetated swales, a bio retention/detention basin bed and a water
tank for stormwater re-use have been incorporated into the proposed development.



The following factors have been identified as potential contributors which can adversely affect
stormwater quality draining from the site:-

               Silt and sediment erosion
               Gross Pollutants
               Hydrocarbon runoff
               Nutrient runoff



5.1      State Planning Policy and Water by Design Assessment


The proposed development has been assessed against the State Planning Policy 2017 and the Water By
Design (Stormwater Quality Deemed to Comply Solutions – 2010).



The proposed residential development involves a land area greater than the trigger value of 2500m2 for
stormwater quality measures as required in the State Planning Policy 2017 and the Water By Design -
Stormwater Quality Deemed to Comply Solutions - 2010. Therefore, stormwater quality treatment is
warranted for the proposed development.




SCG Consulting Engineers                    Page 8                          SCG Ref: 31131(SWMP).RevA