Part I - Other Considerations - Richmond Valley Council

Richmond Valley Development Control Plan 2012(2) Treatment TrainThe “Treatment Train” is a concept for stormwater quality treatment describedin the NSW EPA Managing Urban Stormwater Series.To gain optimum stormwater quality outcomes it is desirable to combine 2 ormore Stormwater Quality Devices or management approaches. Thiscombination of treatment devices forms a stormwater treatment “train.” TheTreatment Train consists of:‣ Primary Level Treatment – screening of gross pollutants, sedimentationof coarse particles.‣ Secondary Level Treatment – Sedimentation of finer particles, filtration.‣ Tertiary Level Treatment – enhanced sedimentation and drainage,biological uptake, adsorption onto sediments.I9.3 WSUD PrinciplesFigures I9.1 & I9.2 provide diagrammatic examples of common WSUDfeatures utilising a source control approach. Figures I9.3 & I9.4 providediagrammatic examples for WSUD approaches for larger subdivision andneighbourhood scale developments.(1) WSUD Road Design and Lot Layout PrinciplesPrinciples of WSUD road design and layout are:‣ The design should promote the retention of the existing land form. Cutand fill is to be avoided and minimised where possible.‣ The design and layout should retain water courses.‣ The design should minimise stormwater runoff and peaks by avoidingthe channelling and concentration of flow and making use of existing sitetopography, natural drainage lines, soils and vegetation to treat, detain,retain and infiltrate stormwater.‣ Street layout should be designed to fit the topography so as to avoid therequirements for cut and fill.‣ Streets are not to be constructed within natural drainage lines.‣ Street design and layout should take into account native vegetation.‣ The street layout should avoid extended street lengths runningperpendicular to the slope so as to reduce runoff velocities.‣ Carriageway widths should be designed to minimise the amount ofimpermeable area but recognising that there will be a demand for whichmust be addressed either within the properties or on street.‣ Street design is to take into account the cleansing of stormwater throughthe use of landscaping, grass swales, filter strips, infiltration pits andoil/grit separators.‣ The design of the road cross section is to take into account the majorstormwater runoff events whilst allowing for vehicle safety.‣ The piped drainage scheme should take into account possibledecreased flows, where the decreases to the design events can bePart I – Other Considerations – Water Sensitive Urban Design I.90