Stormwater assessment services
Stormwater assessment and management advice that satisfies council requirements and protects receiving waters.
Stormwater assessment addresses what happens to rain that falls on a developed site — how much runs off, what it carries, and where it goes. As sites are built out, natural infiltration is replaced by hard surfaces, changing both the volume and quality of runoff reaching downstream drains and waterways. Environmental Specialists Australia assesses stormwater quality and management for development and infrastructure projects, helping proponents meet council targets while limiting the pollutant load that leaves the site.
Most Australian councils apply water-sensitive urban design principles and set pollutant reduction targets that development applications must demonstrate they can meet. Our consultants assess proposed drainage and treatment arrangements, advise on measures such as bioretention, swales, and gross pollutant traps, and prepare the supporting documentation councils expect. The emphasis is on treatment that is realistic to build and maintain, rather than designs that look effective on paper but fail in operation.
When is this service required?
- Development applications requiring a stormwater management plan or quality assessment
- Sites where council sets pollutant reduction or water-sensitive urban design targets
- Projects increasing impervious area and changing runoff behaviour
- Industrial or commercial sites with runoff that may carry contaminants
- Integration of stormwater treatment into landscape and drainage design
- Assessment of downstream impacts from changed runoff quality or volume
Our process
- Requirements review: Review of council controls, pollutant targets, and water-sensitive urban design expectations for the site.
- Runoff characterisation: Assessment of the site layout, impervious areas, and likely runoff quality generated by the development.
- Treatment assessment: Assessment of proposed treatment measures and modelling of their pollutant removal performance.
- Documentation: Preparation of a stormwater quality assessment and management plan for lodgement with the application.
- Approval support: Responses to council comments and refinement of measures to satisfy assessment conditions.
What we deliver
- Stormwater quality assessments demonstrating target compliance
- Water-sensitive urban design advice and treatment recommendations
- Pollutant load modelling outputs
- Stormwater management plans for development applications
- Maintenance and operational guidance for treatment assets
- Responses to council requests for additional information
Frequently asked questions
- What is a stormwater management plan and when is it needed?
- It is a document showing how a development will manage the quantity and quality of runoff it generates, usually required as part of a development application. Councils typically ask for one where a project increases impervious area or where pollutant reduction targets apply to the site.
- What does water-sensitive urban design mean in practice?
- It is an approach that manages stormwater close to its source using features such as bioretention basins, swales, rain gardens, and permeable surfaces. The aim is to slow runoff and remove pollutants before they reach waterways, rather than piping everything straight to a drain.
- How do you demonstrate that pollutant targets are met?
- We model the pollutant loads generated by the site and the removal performance of the proposed treatment train, then compare the result against the reduction targets set by council. The modelling outputs and assumptions are documented so the assessing officer can follow the basis for the conclusion.
- Can stormwater treatment be designed to suit the site landscape?
- Yes. Effective treatment usually works best when integrated with the landscape and drainage design rather than added at the end. We advise early so treatment measures fit the site constraints, are practical to maintain, and complement the overall development layout.