Landslip Risk AssessmentSouth Gippsland

Hillslope conditions vary across the district

The Strzelecki hills are a prominent part of South Gippsland’s landscape. The West Gippsland Regional Catchment Strategy identifies erosion and landslips among the area’s land-management issues. This regional context does not mean that every hillside is unstable.

Geological mapping describes sandstone and mudstone across much of the ranges, with basalt also present in areas around Leongatha and Dumbalk. Weathering, soil depth, water and the shape of the slope vary locally. These broad descriptions are background information, rather than a substitute for evidence from a particular property.

Erosion and landslip describe different processes

Erosion is the removal and transport of soil or other material, for example by flowing water. A landslip involves movement of a mass of soil or rock down a slope. The processes may occur together, but visible erosion does not on its own establish an active landslip.

Similarly, mapped susceptibility is not a calculated level of risk for a particular development. The current ground conditions, potential movement and what could be affected need to be distinguished.

The current EMO1 assessment pathway

EMO1’s application requirements provide for a Geotechnical Assessment report or a Geotechnical Declaration and Verification (Form A), prepared by a suitably qualified geotechnical practitioner. A Geotechnical Assessment should state whether a Landslip Risk Assessment is required. Where it is required by that assessment, an LRA must be prepared.

The schedule also provides for a Minor Impact declaration (Form D) to justify why a Geotechnical Assessment is not required, where applicable. It identifies circumstances in which written assessments are not required, based on Council’s opinion about whether the proposal would adversely increase landslip risk on the site or adjoining or nearby land.

These are qualified pathways, not interchangeable options an applicant can select without considering the site and proposal. Council may require independent peer review of application documents.

Access, earthworks and water belong on the plan

The EMO1 information requirements extend beyond the building footprint. They include proposed access and its cut and fill, retaining walls, vegetation changes and existing development and water-related infrastructure on the subject and adjacent land. Subdivision and dam proposals have additional specific information requirements.

When checking the property’s planning map, use a site plan that captures the whole proposal. A house location considered separately from a new driveway, excavation or drainage change may give an incomplete picture of the development.