Slope Instability

Slope instability is the term used to describe the risk of slope failure, such as landslip and subsidence. Many properties in the City of Ryde carry some degree of risk of slope failure. Properties identified in accordance Council’s adopted slope instability management policy are required to address and respond to this risk when undertaking development activity. As a result, this would be a consideration during the development assessment process.

To check if your property is affected by slope instability please download and view the maps below. This information will also be declared on all planning certificates for the property.

For more information about slope instability affectation, view the Slope Instability Reports, advice and slope instability risk zones notes below.

Related Documents

Slope Instability Risk Zones

This is a quick reference sheet describing the characteristics of each of the landslip risk zones and a general indication of development activity implications for affected properties.

Coffey Report 1991

The Coffey Report was prepared in May 1991. It identifies land impacted by slope instability and divides these into low, moderate and high risk zones.

Note: In this report, drawings nos. S9378/1-2 and S9378/1-3 are not provided as attachments as indicated. However, the slope instability risk zones referenced in those drawings are shown in drawing no S9378/1-1 which is attached to the report. The drawing provides the same information as the other drawings but at a higher scale. 

Geotechnique Report 2002

The Geotechnique Report was prepared in July 2002. It provides additional detail regarding the moderate risk landslip zone established in the Coffey Report.

Geotechnique Advice 2003

This advice was provided by Geotechnique in 2003. It relates to areas affected by extensive man-made infill. These are identified on Council’s maps and planning certificates as bearing risk of subsidence.

More Information

For more information about development pathways and requirements for your property, please contact Council on 9952 8222 to book a time to speak to a duty planner.