Planning · Sunshine Coast
Landslide hazard and steep land overlay Sunshine Coast: development checks
What developers should check when a Sunshine Coast site is affected by the landslide hazard and steep land overlay, including slope, geotechnical risk, access and earthworks.
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Why steep land is a separate feasibility problem
Steep land can quietly destroy a development budget. It changes driveway grades, earthworks, retaining, drainage, construction access and sometimes minimum lot-size outcomes. On the Sunshine Coast, it can also trigger the Landslide hazard and steep land overlay.
The Sunshine Coast Planning Scheme identifies landslide hazard areas and steep land through the Landslide Hazard and Steep Land Overlay Maps. Steep land can include slopes of 15% or greater, and mapped sites may require planning scheme policy guidance and site-specific geotechnical assessment.
What the overlay is trying to avoid
The overlay is about risk to people, property and infrastructure. The planning scheme points to avoiding development on steep land where risk is unacceptable and ensuring any necessary stabilisation measures identified by site-specific geotechnical assessment are implemented.
For developers, this means slope is not just a contour-line inconvenience. It can determine whether the layout, access and earthworks are acceptable.
Civil issues to check early
Check driveway grade, road tie-in levels, retaining wall heights, cut and fill, building-pad levels, stormwater velocity, scour, construction access and whether the site can be drained without concentrating flow onto neighbours.
Compare layouts that follow the contours with layouts requiring major excavation. Record retaining, temporary works and drainage implications before selecting the building levels.
What information helps
A feature and level survey is extremely valuable. Add the Development.i site report, overlay mapping, any geotechnical information, photos of the site and surrounding roads, and the proposed development yield.
With those inputs, CivilCity can quickly flag whether the site needs deeper geotechnical advice, a different access strategy, or a lower-impact layout.
Coordinate geotechnical advice with the actual earthworks
A geotechnical assessment is most useful when it tests the proposed layout and works, rather than an outdated sketch. Moving a building pad or increasing a cut can change the assumptions that were assessed. The civil and geotechnical teams should agree the information needed for access, retaining, surface water and subsurface drainage. Temporary excavation and construction access also matter; a finished retaining-wall arrangement does not describe how the slope will be managed during the build.
| Decision or stage | Evidence to check | Practical outcome |
|---|---|---|
| Concept levels | Survey, proposed cuts and fills, access alignment. | Scope site investigation around the intended works. |
| Retaining and drainage | Geotechnical recommendations and coordinated design. | Avoid directing water into an unsuitable slope or structure. |
| Construction method | Temporary works, access and staging constraints. | Include practical delivery requirements in tendering. |
A slope-responsive option can change the scope
Consider two concepts for a sloping parcel: one uses a broad level pad with substantial cut and retaining, while the other steps the development with the land. Compare driveway transitions, drainage, retaining interfaces and construction access before choosing between them. The geotechnical consultant needs the proposed works for each option to assess the relevant risks. A lower earthworks volume alone does not establish an acceptable design, but it can change the investigation and construction questions. Record which option needs temporary support, difficult access or ongoing drainage maintenance so those obligations remain visible in the feasibility model.
Checklist for your project brief
Use these points to define the next investigation or consultant deliverable.
- Provide the geotechnical consultant with the latest civil concept and advise of later changes to levels or footprint.
- Compare a contour-responsive layout with a heavily benched option before selecting building levels. Record earthworks and retaining implications.
- Clarify the boundary between civil design, structural retaining design and geotechnical advice, including who reviews construction changes.
How CivilCity helps
CivilCity can test steep-site feasibility, coordinate with geotechnical consultants, review access and drainage constraints, and shape civil documentation so the access, earthworks and drainage respond to the surveyed landform.
Common questions
What slope can trigger steep land concern?
The Sunshine Coast Planning Scheme references steep land as slopes of 15% or greater on the Landslide Hazard and Steep Land Overlay Maps, but site-specific mapping and assessment should be checked.
Do I always need a geotechnical report?
Not always for every early conversation, but mapped steep land or landslide risk may require geotechnical input for assessment and design.
What is the biggest civil issue on steep sites?
Driveway grade, retaining, stormwater velocity and safe construction access are common issues that can materially change feasibility.
Official sources and further guidance
Use the current requirements for your property and proposal. Illustrative scenarios describe possible design issues; they are not reported client projects.
Discuss your project
Early civil engineering advice
Share the site report and concept to identify the civil investigations that matter.