Most stormwater jobs are won or lost at the fee proposal stage. If you can tell a client on day one that the site falls 4 m to the rear, drains away from the street, sits inside the overland flow overlay and has no obvious lawful point of discharge, you have already earned the job. Here is a desktop workflow that gets you there in about an hour, using free state data and one property lookup.
Step 1: Boundary and contours
Start with the lot in CAD. You want the boundary and the best contours available, clipped to the lot with a margin so you can see the upstream catchment.
In Queensland the state publishes 1 m LiDAR contours over most urban areas. Getting them for one lot through QSpatial is a GIS job. PlanInsight does it in one download: a DXF with the BOUNDARY, CONTOUR_INDEX, CONTOUR_MAJOR and CONTOUR_MINOR layers, elevation-labelled, in metres. The contour DXF guide covers intervals and coverage.
Look at three things immediately:
- Fall. High corner and low corner from the index labels.
- Direction. Does the site drain to the street frontage or away from it? Away from the street is where lawful point of discharge problems start.
- Upstream catchment. Follow the contours uphill. Anything that drains onto the site is your overland flow problem.
Step 2: Watercourses and overland flow paths
The same DXF includes a WATERCOURSE layer from the state hydrography data. A mapped watercourse touching or crossing the lot changes the job entirely. Even a minor drainage line usually brings a waterway corridor or overland flow overlay with it.
Brisbane City Council maps overland flow paths in its Flood Awareness Map and the City Plan flood overlay. Other SEQ councils have their own equivalents. The contours will often show you the flow path before the overlay does, because the overlay is modelled and the contours are measured.
Step 3: Flood overlay check by address
Every planning scheme in Queensland has a flood hazard overlay. The overlay code determines whether stormwater and flood assessment is required, what freeboard applies, and whether fill is restricted.
PlanInsight shows the planning zone and overlays for the lot on the property page, so the “flood check by address” step is part of the same lookup. Confirm it against the council’s own mapping before you write anything in a report, but for the fee proposal it is enough.
Watch for these overlay types across Queensland schemes:
| Overlay | What it usually means for the job |
|---|---|
| Flood hazard (creek/river) | Flood study or council flood level required, freeboard, fill controls |
| Overland flow path | Flow path must be preserved, possible no-build corridor |
| Coastal hazard / storm tide | Minimum floor levels, sometimes tidal drainage constraints |
| Waterway corridor | Setbacks, possible vegetation and erosion conditions |
Step 4: Lawful point of discharge
“Lawful point of discharge” is one of the most searched phrases in this space and one of the least well explained. In Queensland it is defined in the Queensland Urban Drainage Manual (QUDM). In practical terms, stormwater must leave the site to a point where discharge is lawful: a council kerb and channel, an underground drainage pit, a mapped watercourse, or a drainage easement across a downstream lot.
The desktop check:
- Does the site drain to the frontage? If yes, the kerb or a council pit is usually the discharge point.
- If it drains to the rear or side, look at the contours across the neighbouring lots. Where does water go?
- Check the title and survey plan for a drainage easement in your favour. The survey plan guide explains where to find easements on the plan.
- If there is no easement and no council infrastructure downhill, flag it. The client is looking at negotiating an easement, an on-site detention solution, or a pump-out, and each of those is a different fee.
Getting that into the proposal is what separates an engineer who scoped the site from one who quoted blind.
Step 5: Existing infrastructure
Lodge a Before You Dig Australia enquiry. Utility plans will show council stormwater pipes, Urban Utilities sewer and water, and any private services. PlanInsight can lodge the BYDA enquiry against the property and collect the PDFs for you. See the BYDA for consultants guide for turnaround times and expiry.
Remember that a BYDA enquiry lodged for scoping is not a substitute for a project-referenced enquiry before excavation.
Step 6: What goes in the fee proposal
By now you can write a scope with real numbers in it:
- site fall and drainage direction
- upstream catchment area from contours
- overlays affecting the site and the assessment they trigger
- whether a lawful point of discharge is evident, and if not, the options
- whether a feature survey is needed before design
- whether a flood study or council flood level request is needed
That is a proposal a client can act on, and a scope you can defend.
Development applications on neighbouring lots
One more check that takes thirty seconds. PlanInsight shows live and historical DAs for the lot in supported councils. A recent subdivision or bulk earthworks approval next door often comes with drainage conditions and sometimes a new easement or pit that changes your discharge options.
Try it on your next Queensland enquiry. The consulting engineers page has the full picture of what is on the property screen.