Part I - Other Considerations - Richmond Valley Council

Richmond Valley Development Control Plan 2012‣ Increases in erosion as a result of peaks, velocities and increases in thenumber of bank full events.‣ Increases in nuisance flooding, flash flooding, property damage and riskto public safety.‣ Increase contaminant loading due to increased runoff volumes andreplacement of vegetated filters with concrete systems.‣ Aquatic biodiversity decline as communities become disrupted as aresult of frequent and elevated stormwater pulse events.‣ Increased demand for drainage infrastructure and treatment devices.(2) ObjectivesThe objectives of element are to:‣ To maintain the sites mean stormwater volumes, peak flow rates, andrunoff event frequency as near as reasonable to sites originalcharacteristics.‣ To reduce flooding, property damage, and risk to public safety todownstream areas as a result of increased impermeability, increaserunoff volume and changes to drainage line upstream.‣ To protect receiving environments from the impacts of changes tostormwater characteristics.(3) Performance TargetsPerformance requirements for stormwater volumes and drainage are providedin Table I9.3Table I9.3 Stormwater TargetsElementPeak flowrates (m3/s)Mean annual stormwater postdevelopment volumes (ML/yr).TargetThe following targets apply:‣ Flowrates at any point are not to increaseduring storms for the 2 and 5 year ARIevent; or‣ As specified within specific drainage subcatchment policy recognised by Council; or‣ As specified within Council standards.The following targets apply‣ Mean annual stormwater volumes reducedby at least 10 % from baseline; or‣ As specified within specific drainage subcatchment policy recognised by Council; or‣ As specified within Council standards.(4) Variations to TargetsCouncil may vary those targets from above where:‣ Environmental or infrastructure factors require alternate performancetargets; or‣ A Masterplan, Integrated Urban Water Management Plan, StormwaterManagement Plan, Estuary Management Plan, Threatened SpeciesPart I – Other Considerations – Water Sensitive Urban Design I.100