271117 Techtonic GeoTech Cooroy Mtn Rd

Mr Ken Freeman                                                                                    17385-001-Rev0
                                                                                                27 November 2017

4.0     ASSESSMENT OF LAND STABILITY
4.1    Existing Conditions
Noosa Shire Council (NSC) landslide hazard overlay mapping (Refer extract in Text Figure 7) indicates that
the lot has some areas assigned as being a “Landslide Hazard Area.”




      Existing house




Text Figure 7: Extract from Noosa Shire Council Hazard Overlay (courtesy Noosa Shire Council Interactive Maps)

It should be noted that the NSC map is a broad-scale indication, applied at a coarse resolution, of the
potential landslide hazard only and is superseded by site specific assessment. The areas of the proposed
construction works, and the existing house are not designated as a “Landslide Hazard Area.”

4.2    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 2 on the
following page, and the Qualitative Terminology for Use in Assessing Risk to Property is also attached.
 Table 2: 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




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