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

Project No. 1-22543                                                                                                                  Page | 12
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




    4.6 Risk Determination and Evaluation - Persons
Evaluation of the risk to life must be carried out on a quantitative basis to be consistent and for
comparison with acceptance criteria. To do this, the indicative probabilities given in Appendix C
of PNGLRM (2007) may be adopted as there are no other frequency/probability data. The
assessment results are shown in Table 4.

The analysis is based on formula 1 in Section 7 of PNGLRM (2007), i.e.:-

                                    R(LoL) = P(H) × P(S:H) × P(T:S) × V(D:T)
Where                  R(LoL) = The risk for Loss of Life
                       P(H) = Annual probability of the Landslide - based on Section 4.3
                       The other factors are outlined in Section 4.4.4

The acceptance criteria (Table 5) adopted for this assessment is outlined in Section 8 of
PNGLRM (2007) which suggests the following Risk to Life as outlined in Table 4.

Based on the assessment below, the risk to life for the three hazards has been assessed
to be Acceptable.

TABLE 4            SUMMARY OF RISK TO LIFE CALCULATIONS
                                      Assessed
Haz        Area of Site                                         P(H)        P(S:H)        P(T:S)        V(D:T)         R(LoL)     Assessment
                                      Likelihood
                                                                  -5                                                         -7
                                                              10 to                                                   7x10 to
  A         Overall Site          Rare to Unlikely                -4           1.0           0.1           0.7              -6    Acceptable
                                                               10                                                      7x10
                                                                -5                                                        -7
             Proposed                                         10 to                                                   7x10 to
  B                      2        Rare to Unlikely                -4           1.0           0.1           0.7              -6    Acceptable
           internal cuts                                       10                                                      7x10
                                                                  -6                                                         -8
           Overall Site –          Barely Credible            10 to                                                   7x10 to
  C                    3                                         -5            1.0           0.1           0.7             -7     Acceptable
            long term                 to Rare                  10                                                      7x10
Note:-
1. Refer Appendix B of “Practice Note Guidelines for Landslides Risk Management (2007)”.
2. Assumes all cuts supported by engineer designed retaining walls.
3. Assumes it’s addressed by landscaping and control of drainage and overland flow.



    4.7 Risk Summary
A summary of the results of the risk assessment for the existing site condition as detailed in
Sections 4.6 and 4.7 are as follows:-

          Risk to Property - This is outlined in Table 3 and provided the recommendations of this
           report are followed, then the risk of any slope stability occurring on the site has been
           assessed as Very Low to Low or Low.
          Risk to Persons – This is outlined in Table 4 and based on that assessment, the risk to
           persons from the identified hazards was assessed as Acceptable.

We also recommend that once a retention design has been completed, it be reviewed by
Soil Surveys Engineering to ensure compliance with this report and that no additional
stability issues have been created.




                                                                                                               SOIL SURVEYS