Geotechnical Investigation

                                    PROPOSED CALILE HOTEL NOOSA DEVELOPMENT
                                    3 – 7 SERENITY CLOSE, NOOSA HEADS

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


                                                                            Given the low to moderate natural gradients through
                                                                            the proposed building area and retention of batters
 1: Failure through very loose to                                           proposed it is considered Unlikely that a landslip
loose natural sands above the        Unlikely      Medium          Low      would develop in these materials, subject to
foundation depth                                                            implementation of the recommendations in Section 4.
                                                                            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 medium
                                                                            dense (or denser) natural sand below the proposed
 2: Deep failure through the                                                foundation depth is assessed as Rare due to the lack of
medium dense (or denser) sands        Rare          Major          Low      precedence of such movements locally, no signs of any
below the foundation depth                                                  existing slope instability and a lack of groundwater.
                                                                            Although the 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 (if required) as outlined in Section 6.4, is
 3: Instability through temporary                                           assessed as Rare, subject to detailed design by a
sheet pile retention system, or                                             suitably qualified RPEQ and construction by a specialist
                                      Rare          Major          Low
similar, as discussed in Section                                            contractor which accounts for the required factors of
6.4.                                                                        safety against slope instability. Although the
                                                                            consequence of such a failure would be Major, the
                                                                            resultant risk is Low as per AGS2007.



The potential impacts on slope stability of the development components have been assessed, and the
measures recommended below in Section 4 have been designed to mitigate those impacts.

5.2.2        Quantitative Assessment
In order to estimate the factor of safety (FOS) against slope instability for the proposed development,
numerical analysis has been conducted using Slope/W. The ground surface profile has been modelled using
a combination of preliminary design drawings and slope angles measured in the field by Tectonic. The
analysed subsurface profiles were compiled based on the results of our subsurface investigation. Some
inferences regarding subsurface conditions were made between test locations. A minimum FOS against
global instability of 1.5 is the commonly adopted industry standard for long term conditions.
No groundwater was encountered at the time of investigation. Given the gradients across the site and highly
permeable nature of the sandy soil, development of shallow groundwater is considered unlikely. Should
groundwater seepage be encountered during construction Tectonic must be notified to assess the impacts
on temporary instability.

To replicate future landscaping and light live loads, a surcharge load of 10 kPa has been applied to areas
with no significant structures. Although building loads were not available at the time of reporting; a gross
building load of 10 kPa per floor level has been applied to building areas likely to be supported using high-
level footings (i.e. up to 50 kPa). Other areas will be supported by piles taken into the underlying medium
dense (or denser) natural sands.

Soil shear strength was based upon effective parameters which were estimated based on our interpretation
of the subsurface investigation results, while also considering the values recommended for similar materials
in Appendix D of Australian Standard AS4678-2002 Earth Retaining Structures. Adopted soil parameters
are shown on the Slope/W outputs presented in Text Figures 11 to 14 on the following pages. Analyses
were undertaken for specified ranges of landslide failure surface entry and exit points that could impact the
proposed development. It is assumed that all future controlled filling will use site won sands, which have
been modelled accordingly.




7 October 2022
Report No. 22239-001-Rev0                                   10