Stormwater & Civil Engineering
Every development in Brisbane — from a new home to a large commercial project — has a stormwater footprint. The buildings, driveways and hardstand areas that cover the site create impervious surfaces that increase the volume and velocity of runoff, which in turn increases the risk of flooding and downstream erosion. Managing this runoff is a council requirement, an engineering responsibility and, in Brisbane's flood-prone catchments, a critical community obligation.
Brisbane Structures provides civil and stormwater engineering services for residential and commercial projects across Brisbane and south-east Queensland. Our RPEQ engineers design stormwater drainage systems, on-site detention (OSD) tanks, water quality treatment measures and hydraulic infrastructure — and produce the reports, plans and council submissions needed to get your development approved.
As a firm that also provides structural engineering, Brisbane Structures can manage both structural and civil engineering for your project — a single point of contact for the engineering disciplines most commonly needed in residential and commercial development. This coordination saves time, reduces errors and keeps your project on schedule.
Stormwater drainage and OSD design for new homes, extensions, duplexes and small residential developments.
Hydraulic reports, MUSIC modelling and stormwater management plans for commercial development applications.
Drainage network design for residential and commercial land subdivisions — from lot drainage to trunk infrastructure.
Flood level assessment, overland flow path analysis and flood impact reports for Brisbane City Council submissions.
Our Stormwater Services
Brisbane Structures provides a comprehensive civil and stormwater engineering service for projects of all scales. Our deliverables are formatted to meet Brisbane City Council, SEQ Water, and Queensland Development Code requirements.
OSD & MUSIC
Two of the most common stormwater engineering requirements we encounter in Brisbane are on-site detention (OSD) and MUSIC water quality modelling. Both are required by Brisbane City Council for most development applications above a certain size. Here is what they involve and why they matter.
On-Site Detention (OSD) is a stormwater management measure that temporarily stores runoff from your site during a rainfall event, then releases it slowly to the downstream drainage network. The purpose is to ensure that your development does not increase peak flows in the downstream network — protecting lower-lying properties from flooding. Brisbane City Council's hydraulic requirements specify the design storm (typically the 10-year ARI event), the maximum allowable release rate (the pre-development rate), and the minimum storage volume required. Brisbane Structures calculates the required storage volume, designs the tank and outlet structure, and produces the plans and calculations needed for council approval.
MUSIC Modelling is required to demonstrate that a development meets the council's water quality objectives — specifically, that a defined percentage of annual pollutant loads (suspended solids, nutrients, gross pollutants) are treated before runoff leaves the site. MUSIC software models the performance of different treatment measures (rain gardens, gross pollutant traps, sediment basins) and allows engineers to optimise the treatment train to achieve the required pollutant reductions. Brisbane Structures carries out MUSIC modelling and produces the associated Stormwater Quality Management Plan (SQMP) required for development approval.
From first enquiry to council-ready hydraulic submission
Tell us about your project and site. We'll confirm the scope of stormwater engineering required and provide a fixed fee.
We review site plans, council flood overlays, existing drainage infrastructure and any geotechnical or survey data.
Drainage design, OSD sizing, MUSIC modelling and hydraulic calculations — all to council standards and requirements.
RPEQ-signed hydraulic plans and reports — formatted for council submission and ready for your DA application.
Common Questions
OSD temporarily stores runoff from your site during rainfall, then releases it slowly to the drainage network — reducing peak flows and flood risk. Brisbane City Council requires OSD for most new developments and significant alterations that increase impervious area. We design OSD systems and produce the council-required hydraulic calculations and plans.
MUSIC is software that models stormwater quality treatment measures — rain gardens, bioretention, gross pollutant traps. Brisbane City Council requires MUSIC modelling for most medium and large development applications. Brisbane Structures carries out MUSIC modelling and produces the Stormwater Quality Management Plan (SQMP) required for approval.
For a standard house draining naturally to the street, a hydraulic plumber may be sufficient. However, for properties with complex drainage, rear drainage, flood overlays, OSD requirements, or DAs requiring a hydraulic report, an RPEQ civil engineer is required. We assess your site and advise what level of engineering is needed.
A hydraulic report documents how stormwater will be managed on and around your site — catchment analysis, runoff calculations, drainage design, OSD sizing, water quality treatment and flood assessment. It is required by Brisbane City Council for most development applications and many building approval applications involving significant impervious area increases.
Yes. Brisbane Structures provides both structural engineering and civil/stormwater engineering — a single firm for the two engineering disciplines most commonly needed in residential and commercial development. This coordination saves time, reduces errors and keeps your project on schedule.
For a standard residential lot requiring a stormwater drainage plan and OSD design, we typically deliver within 1–2 weeks of receiving site plans. More complex projects involving MUSIC modelling and hydraulic reports for DA applications take 3–4 weeks. We confirm a delivery timeline during the initial consultation.