Stormwater Drainage Plan
Stormwater is assessed as part of every DA's general merit assessment, but the engineering standard comes from your council's own specifications - typically requiring on-site stormwater detention (OSD) so your development does not increase peak flood flows onto downstream properties. The plan and detention design scale with how much hard surface - roof, driveway, car park - your project adds. We coordinate the civil engineer and integrate the design with your DA package.
Free planning consultation
- 1–2 weeks
- Quoted per project - typically from $1,200 + GST
- Quoted fixed after a free scope check
Why this sits with the civil engineer, but needs coordinating
The engineering standards for stormwater come from each council's own specification, not a single state-wide rule, so the same detention volume calculation can produce a different answer between neighbouring council areas. Getting the discharge point and detention sizing right the first time avoids a request for further information late in the assessment.
Source: Environmental Planning and Assessment Act 1979 (NSW), s 4.15; relevant council engineering specifications and Development Control Plans.
How it works
Site and council requirements
2–3 days
Confirm your council's engineering specification and discharge point for the site.
Detention design
3–5 days
On-site detention sized against the impervious area your development adds.
Integration
2–4 days
Drainage plan cross-checked against landscape, structural and civil documentation before lodgement.
What we take off your hands
What EHUP handles
- Coordinating the civil/hydraulic engineer for your site
- Confirming your council's specific OSD and discharge requirements
- Integrating the drainage design with the rest of the DA package
- Scaling the design correctly for commercial and industrial impervious areas
What you don't have to deal with
- A drainage design that conflicts with the landscape or structural plans
- Underestimating detention capacity for a larger roof or hardstand area
Frequently asked questions
What is on-site stormwater detention?
A tank or basin sized to hold peak stormwater runoff on your property and release it slowly, so your development does not increase the flow hitting downstream properties during a storm. Almost every council requires it once impervious area increases meaningfully.
Does this apply to a simple house or renovation?
Usually, once new roof or paved area is added, though the design is far smaller and simpler than for a commercial or industrial project. Councils typically have a residential-scale OSD requirement even for modest additions.
How much bigger does this get for commercial and industrial sites?
Substantially. Large-format warehouses and hardstand yards generate significantly more runoff than a house, and the detention infrastructure scales accordingly - this is one of the larger engineering tasks in an industrial DA, not an afterthought.
Who actually designs the drainage, you or an engineer?
A civil or hydraulic engineer designs and certifies the drainage system; we coordinate that engineer, confirm your council's specific requirements, and make sure the drainage plan is consistent with the rest of your DA package.
Related approvals
Specialist Reports
Most applications of any size need reports from specialists outside town planning.
Waste Management Plan
Most DAs above a council-set construction value threshold - commonly around $5,000, set locally - need a Waste Management Plan detailing how construction and demolition waste will be sorted, reused, recycled or disposed of, usually against a target diversion-from-landfill rate.
Structural Design & Certification
Structural design and certification is the structural engineer's design and sign-off confirming the building's structural elements - footings, framing, load paths - are engineered to the National Construction Code.
Traffic Impact Assessment
A traffic impact assessment quantifies the trips a development generates, assesses the effect on the surrounding network and intersections, and demonstrates that parking, servicing and access arrangements work.
Access Report
An access report shows council and your certifier that people with disability can reach, enter and use your building.
Why clients choose EHUP
- 10+
- 250+
- 17
- 1
Not sure which approval you need?
Tell us the address and what you want to do. We'll help identify the appropriate planning pathway, whether it is exempt development, complying development or a full DA. Your first conversation is free.