Attachment 5 - Slope Stability Assessment · RAL20/0005

Mr Peter Loxton                                                                                         16162-001-Rev0
                                                                                                           22 July 2016

3.0     ASSESSMENT OF LAND STABILITY
3.1   Existing Conditions
The NSC Landslide Hazard Overlay map (Refer Text Figure 10 below) indicates that the site is located within
a Landslide Hazard Area (pink shading).




                                                                   Site




Text Figure 10: Extract from Noosa Council Natural Hazard: Landslide & Flooding Overlay

It should be noted that the NSC overlay map is a broad-scale indication of the potential landslide
susceptibility only and is superseded by site specific investigation and analysis works. At the time of our
visit, the site did not exhibit any indicators of slope instability, with the ground surface near level.

3.2   Stability Assessment
The risk assessment for this project has been carried out following AGS 2007 Practice Note Guidelines for
Landslide Risk Management. Relative levels of risk and their implications are given in Table 1 below and the
Qualitative Terminology for Use in Assessing Risk to Property is attached.
 Table 1: Stability Risk Levels

 Risk Level            Example Implications(1)
                       Unacceptable without treatment. Extensive detailed investigation and research, planning
       Very High
 VH                    and implementation of treatment options essential to reduce risk to Low; may be too
       Risk
                       expensive and not practical. Work likely to cost more than value of property.
                       Unacceptable without treatment. Detailed investigation, planning and implementation of
 H     High Risk       treatment options required to reduce risk to Low. Work would cost a substantial sum in
                       relation to the value of the property.
                       May be tolerated in certain circumstances (subject to regulators’ approval) but requires
       Moderate
 M                     investigation, planning and implementation of treatment options to reduce risk to Low.
       Risk
                       Treatment options to reduce to Low risk should be implemented as soon as practicable.
                       Usually acceptable to regulators. Where treatment has been required to reduce the risk
 L     Low Risk
                       to this level, ongoing maintenance required.
       Very Low
 VL                    Acceptable. Manage by normal slope maintenance procedures.
       Risk
 Note: (1) The implications for a particular situation are to be determined by all parties to the risk assessment and may
 depend on the nature of the property at risk; these are only given as a general guide.




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