Stormwater Design
Stormwater design is the process of planning, designing, and implementing stormwater management systems to effectively capture, store, treat and release rainfall and runoff from developed areas. The design of such systems is crucial to preventing flooding and water pollution, preserving water quality, and supporting the safe use of waters.
Stormwater management design typically includes the following steps:
- Site Analysis: Assessment of the site’s topography, soil types and drainage patterns to determine potential runoff areas and the options for water control, treatment, and diversion.
- Conceptual Design: Exploring various preliminary designs to identify the best approach for managing stormwater on a particular site.
- Detailed Design: Development of a detailed plan and technical specifications for construction.
- Implementation: Construction of the stormwater management infrastructure, including detention basins, drainage systems, treatment tanks, infiltration systems, and green infrastructure.
- Ongoing Maintenance: Ongoing inspection, maintenance, and operation of the stormwater management system to ensure it continues to function effectively.
An effective stormwater design helps to mitigate the potential negative impacts of stormwater runoff, reduce the risk of flooding, and improve the health and safety of the surrounding community and environment.
When lodging a development application (DA) for a council, a stormwater drainage plan is required before a DA can be issued to the client.

Water Quality Modelling
It is essential that we plan and design appropriate urban and rural stormwater treatment and management systems from individual developments to catchments. A treatment train – the connection of stormwater quality improvement devices – is used to treat stormwater pollutant generation. The main pollutants include the following:
- Suspended solids
- Phosphorus
- Nitrogen
Our engineers model these treatment processes to determine conceptually if the stormwater treatment system can meet water quality requirements set by council. This approach ensures the treatment devices focus on achieving the target pollutants or other objectives, allowing for effective hydraulic and treatment operation.
As hydraulic engineers, we consider in detail council’s requirements and your understanding of our proposed stormwater treatment strategy to save you amendments down the line.
Water Quantity Modelling
Storms can have disastrous consequences in poorly planned urban areas or during heavy rainfall due to ponding and flooding. As hydraulic engineers, our task is to design and analyse cost effective but safe stormwater drainage systems to mitigate flooding, waterlogging, and pollution. We use the applied science of hydrology to determine flow rates, and hydraulics to transport flow through pipes and channels.
The purpose of models is to put the science of hydrology and hydraulics into practice. Models imitate reality through equations and algorithms that output data for our engineers to design a system or analyse site conditions. However, these models can be unstable at times and require proficient hydraulic knowledge to obtain and judge accurate results, a skillset our engineers have and practice frequently.
Why choose Neilly Davies?
Neilly Davies has been designing stormwater drainage systems for residential, commercial, and industrial developments for over 35 years.
The hydraulic engineers at Neilly Davies are also able to issue a Work as Executed certificate (WAE) to certify that the construction of properties have been built according to the intended engineering plans.