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

Project No. 1-22543                                                                                                          Page | 10
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




Based on the above comments and observations on site, the likelihood rating for the scour of
exposed surfaces would be assessed as being Moderate to High which translates to a
Likelihood Descriptor of Unlikely to Likely.

However, if soils are protected from scour as would be expected to be required as part of the
development during and following construction, then the rating would reduce to Very Low or
Low which translates to a Likelihood Descriptor of Barely Credible to Rare.

    4.4 Consequence Analysis

               4.4.1   General

As part of the assessment of the risk of slope instability, the analysis of the consequence of any
failure must also be considered.

This analysis is based on the effect on the following for each type of hazard:-

         i)       Consequence to Property (proposed dwelling)
         ii)      Consequence to Persons within and around the proposed dwelling

               4.4.2   Site Factors

The development consists of the construction of a new residence on the site. The following will
be used to assume consequence:-

              A residence will be constructed with basement level formed by cuts into the existing
               slope.
              Based on the provided drawings, temporary cuts of up to approx. 4.0m to 5.0m will be
               required for the basement (ground floor) near the middle of the site (including near
               boundaries).
              The cuts will be supported initially by temporary engineer designed and certified
               retaining structures during construction and then with permanent retaining structures as
               part of the residence.

               4.4.3   Consequence to Property

For the purposes of this study, a semi-qualitative measure of consequence to property will be
adopted, as outlined in Appendix C of PNGLRM 2007c.

If slope instability were to occur, the aspect of property most at risk would be the proposed
residential structure located on the subject part of the site.

Based on Appendix A of PNGLRM 2007c the residential structures at risk would be classified as
Importance Level 2.

Considering the above information the consequence to property for each of the hazards is as
follows:-

              Hazard A – Existing slopes – Minor to Medium
          Hazard B – Proposed cuts – Medium as could affect several areas of the site or
           adjacent sites during construction of the retaining walls.




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