Geotechnical Stability Report · OPW24/0017

GMW Projects Pty Ltd                                                                                      24008-001-Rev0
                                                                                                          31 January 2024

1.2       Method and Scope of Investigation
As part of our slope stability assessment, a desk-top study was carried out comprising a review of published
geological maps, slope stability studies and a site classification ‘soil test’ report by Global Testing
(Global, Ref. Job No. 23-1410, dated 11 December 2023).
A walk-over survey was conducted to make an appraisal of the general condition of the site in regard to
topography, drainage, vegetation cover, geology, erosion, and condition of existing structures. The walk-
over survey was carried out by an experienced geotechnical engineer from Tectonic on 18 January 2024.

The results of the desk-top study and walk-over survey are included in Section 2 below.

1.3       Qualifications of Responsible Engineer
This report has been prepared by Mr Michael Cocks, an RPEQ with over nine years of experience in
geotechnical engineering, including a number of slope stability projects on the Sunshine Coast.


2.0        DESCRIPTION OF EXISTING CONDITIONS
2.1       Geology and Subsurface Conditions
Available geological information 1 indicates that the site is underlain by the Holocene age blowout dunes,
comprising ‘quartz sand’’.




                                                                     Approx. site location




Text Figure 3: Extract of Laguna Bay Surface Geology Map

The Global investigation comprised two boreholes (designated BH1 and BH2) within the proposed
external extension areas. Consistent subsurface materials were described in the borehole logs
comprising loose sand from the ground surface to depths between 0.8 m and 0.9 m below ground level
(BGL), below which both boreholes were indicated to be terminated due to collapsing. Dynamic cone
penetrometer (DCP) testing extended below the borehole termination depths, and indicated that the
sands became medium dense at depths between 1.1 m and 1.5 m BGL, extending to the DCP
termination depths of 2 m BGL.




1
    Queensland Government, Department of Mines and Energy, 1:100,000 Laguna Bay Surface Geology Map, Sheet 9545, 2018




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