An Example Of Semi Quantitative Landslide Risk Management For An Individual Lot In Northern Sydney

Bruce F Walker

This case history is based on a site on the western slopes of the Warringah Peninsula, Northern Sydney, an area which has had a history of landsliding since the early 1970’s, and possibly earlier. The paper by Burgess (1987) gives a useful reference to the historical background, geological setting, causes of instability and general geological model. Some specific case histories are given by Burgess to demonstrate the type of engineering and administrative solutions that have been adopted to control the risk from instability.

This paper presents a case history which represents a fairly routine stability risk assessment commission which would be completed by geotechnical consultants practicing in the area. The assessments are required as part of the development application process to demonstrate what measures, if any, are required to control the risks associated with potential instability. The case history has been “adjusted” to include some features that have been found on a number of different sites in the same general area. The approach adopted for the analysis and reporting demonstrates how the Landslide Risk Management methodology (Australian Geomechanics Society 2000) can be applied in a semi quantitative manner as a tool to assist judgement of the extent of risk and risk management that might be required.