Fifteen Years Of Slope Stability And Risk Assessment For Local Government Planning In Victoria: A discussion of common mistakes and shortcomings

Over the past 15 years, a number of local governments in Victoria have introduced Erosion Management Overlays (EMOs) to manage slope stability and landslide risk through the town planning process. Local government areas with Erosion Management Overlays include Yarra Ranges, Colac- Otway, Moreland, Frankston and Mornington. Whilst there are some local nuances, the requirements of the EMOs under different Local Government Authorities (LGA) are essentially the same. A key requirement is that a geotechnical assessment or landslide risk assessment is undertaken for development in areas susceptible to landslide or other slope degradation processes. The intent of the geotechnical assessment is to identify whether a proposed development will be at risk from slope instability, if it will create or increase landslide risk and, if required to estimate the magnitude of the risk and evaluate the risk against a criteria.

The authors have in excess of 15 years each of peer review of geotechnical assessments on behalf of local government and combined have reviewed over 1000 geotechnical assessment and landslide risk assessment reports. This paper presents and discusses some shortcomings gleaned from review of geotechnical assessment and landslide risk assessment for residential development within areas subject to EMOs.