Appendix C - Geotech Report · RAL22/0021

                                    PROPOSED RESIDENTIAL DEVELOPMENT
                                    39 PICTURE POINT CRESCENT, NOOSA HEADS

Table 3: Details of Qualitative Risk Assessment for Property (AGS 2007)
                                                                  Assessed
 Hazard                             Likelihood   Consequence        Risk     Comments


                                                                             Given the slightly gentler gradients through the
                                                                             proposed building area and retention system proposed
 1: Building Envelope - Failure                                              it is considered Unlikely that a landslip would develop
through very loose to loose or                                               in these materials, subject to implementation of the
                                     Unlikely      Medium           Low
medium dense natural sands                                                   recommendations in Section 6 (especially footing
above the foundation depth.                                                  depth and type). Given a potential Medium impact
                                                                             from such instability the resultant risk would be Low
                                                                             as per AGS 2007.


                                                                             The likelihood of a deep failure through the dense (or
                                                                             denser) natural sands below the proposed foundation
 2: Building Envelope - Deep
                                                                             depth is assessed as Rare due to the lack of precedence
failure through the dense (or
                                      Rare          Major           Low      of such movements locally, no signs of any existing slope
denser) sands below the
                                                                             instability and a lack of groundwater. Although the
foundation depth.
                                                                             consequence of such a failure would be Major, the
                                                                             resultant risk is Low as per AGS 2007.



                                                                             The likelihood of a slip/failure through the temporary
                                                                             retention system (sheet pile wall, or similar) as outlined in
 3: Instability through temporary                                            Section 6.4, is assessed as Rare, subject to detailed
sheet pile retention system, or                                              design by a suitable qualified RPEQ engineer and
                                      Rare          Major           Low
similar, as discussed in Section                                             construction by a specialist contractor which accounts for
6.4.                                                                         the required factors of safety against slope instability.
                                                                             Although the consequence of such a failure would be
                                                                             Major, the resultant risk is Low as per AGS 2007.



                                                                             As discussed further below, it is Likely that near surface
                                                                             translational failures may occur over the face of the
                                                                             natural dune slope within the site, and in the slope that
                                                                             continues down to Noosa Drive to the north, over the
 4: Dune Slope Below Building
                                                                             design life of the project. However, given the extent of the
Envelope –shallow translational
                                      Likely     Insignificant      Low      recommendations below, it is considered that this will
movements in very loose to loose
                                                                             affect future landscaping/garden areas only, and when
natural sands near surface.
                                                                             considered against the value of the property and that the
                                                                             likelihood for adverse effects to the building is limited, an
                                                                             Insignificant consequence is assessed. Thus the
                                                                             resultant risk is Low as per AGS 2007.




Our assessment indicates that a Low Risk of slope instability could be achieved for proposed residential
development at 39 Picture Point Crescent, and that there would be a Low Risk of slope instability, subject to
implementation of the recommendations outlined in Section 6 (especially around permanent retention of
cuts, adoption of relatively deep piles, and protection from erosion from the dune face).




10 February 2023
Report No. 22511-001-Rev0                                    10