Reference Document - Geotechnical Investigation Report - DBW24/0090 & RAP24/0025

                Rebecca Stead                                                                                            20248-001-Rev0
                                                                                                                       3 September 2020

                3.0       ASSESSMENT OF LAND STABILITY
                3.1     Existing Conditions
                The Noosa Planning Scheme 2020 includes a landslide hazard overlay map (Ref. extract in Text Figure 9).
                Mapping indicates that the site is within a High Landslide Hazard Area.




                                                                               Subject site




                Text Figure 9: Extract from NC landslide hazard overlay mapping

                It should be noted that the Noosa landslide hazard map is a broad-scale indication of the potential
                landslide susceptibility and is superseded by site specific investigation and analysis. No visual signs of
                global slope instability were not observed in the location of the residence or proposed extensions. No
                landslide back scarps or areas of naturally ‘hummocky’ ground were observed.

                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 and the
                Qualitative Terminology for Use in Assessing Risk to Property is also 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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Document Set ID: 23080488
Version: 1, Version Date: 27/06/2024