RFI - Attachment C - Slope Stability Assessment and Geotechnical report · MCU20/0026

Project No. 1-22543                                                                                                          Page | 8
June, 2020
Ref: 1-22543, 2020-05-20, BR SSA VER 1
Sanya Holdings – Slope Stability Assessment and Geotechnical Report - Proposed Residence, 40 Park Crescent, Sunshine Beach




4.0 RISK ASSESSMENT

    4.1 General
For the purposes of this study, the assessment of Risk for the site has been based on risk to
property and risk to persons, where Risk is the product of Likelihood and Consequence.

This method is based on the method outlined in the “Practice Note Guidelines for Landslide
Risk Management 2007” (PNGLRM), produced by the Australian Geomechanics Society, 2007
and is based upon the Risk Matrix in Appendix G.

    4.2 Identification of Potential Hazards on Site
Based on the site walkover, a review of the site information and experience on similar sites, the
following potential hazards have been identified for assessment at the location of the proposed
residence (subject site):-

     A. Shallow landslides on the existing slopes – applies to overall site.
     B. Proposed Cuts – applies to internal proposed cut areas for basement level.
     C. Surface scour on the site during construction – applies to overall subject site.

    4.3 Likelihood Estimation

           4.3.1       Methods of Assessment

The site was assessed and zoned using the method as outlined in MacGregor and Taylor
(2001). The method has been adopted as a slope stability assessment tool and used in both the
Gold Coast and Redlands Shire regional stability assessments.

           4.3.2       Evaluation of Likelihood Rating for Existing Overall Site

Once the relative frequency of slope instability for the site is calculated, MacGregor and Taylor
(2001) suggests a likelihood rating as outlined in Table 2 below.

This rating has then been compared to the Likelihood Descriptor from Appendix C of “Practice
Note Guidelines for Landslides Risk Management (PNGLRM) (2007c)”.

TABLE 2                LIKELIHOOD RATING
          MacGregor and Taylor (2001)                                    Landslide Risk Management (2007c) Appendix C
                                                                                                    Adopted Indicative
 Relative Frequency                  Likelihood Rating                   Likelihood Descriptor       Value of Annual
                                                                                                        Probability
                                                                                                               -6
           < 0.2                            Very Low                         Barely Credible                 10
                                                                                                           -5     -4
         0.2 to 0.6                           Low                            Rare to Unlikely           10 to 10
                                                                                                           -4     -3
         0.6 to 2.0                         Moderate                       Unlikely to Possible         10 to 10
                                                                                                           -3     -2
         2.0 to 6.0                           High                          Possible to Likely          10 to 10
                                                                                                               -1
           > 6.0                            Very High                        Almost Certain                  10
Note: 1. McGregor & Taylor (2001).
      2. Likelihood adopted based on Landslide Risk Management (2007c), Appendix C.




                                                                                                               SOIL SURVEYS