220328 - Edwards Street - Slope Stability Assessment

Bev Jenner Const.                                                                                              22073-001-Rev0
C/- Westera Partners                                                                                            25 March 2022

1.3        Qualifications of Responsible Engineer
This report has been reviewed by Ashley Davey, an RPEQ with over 27 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 Pleistocene age parabolic dunes
comprising “quartz sand” (Ref. Text Figure 3 below).




                                                                          Approx. site location




Text Figure 3: Extract from Laguna Bay Surface Geology Map

Materials encountered in the Unearthed boreholes were consistent with the published geology, comprising
an upper layer of silty sand, then relatively ‘clean’ dune sands below. Subsurface conditions are summarised
as follows, with the in situ strength information being inferred from Tectonic’s DCP testing:
           Loose Silty Sand to between 0.6 m and 0.7 m BGL; then
           Loose to Medium Dense Sand to depths of up to about 2.1 m BGL; overlying
           Medium Dense Sand to the maximum depth of the Tectonic investigation (3.9 m BGL).

Groundwater seepage was not encountered during the Unearthed ‘soil test’ fieldwork, with the soils generally
being described as moist.

Unearthed has classified the site as Class S in accordance with AS2870, with a characteristic surface
movement due to normal seasonal moisture variation only (ys), inferred to be ≤20 mm.




1
    1:100,000 Laguna Bay Surface Geology Map, Sheet 9545, Dept. of Natural Resources, Mines and Energy, 2018




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