Geotechnical Investigation Report

J001369-001-R-Rev0                                                                                                                             August 2021


5.0            INVESTIGATION FINDINGS
5.1         Desktop Study
The Gympie Special Geology Map1 indicates that the site is underlain by Pleistocene aged quartz sand dune
deposits (Qpd2). Image 2 below shows an extract from the geology map.




                                                                                            Approximate site location




Image 2: Extract from Gympie Special Geology Map1.

5.2         Subsurface Conditions
The subsurface conditions encountered in the boreholes generally comprised the following:

        ▪      TOPSOIL: comprising loose sand to depths of 0.1 m and 0.18 m BGL; overlying
        ▪      FILL: comprising loose sand to 0.5 m depth with possible fill further observed to 1 m depth BGL in
               HA1; overlying
        ▪      AEOLIAN SOIL: comprising loose to medium dense sand becoming dense from about 1.5 m depth
               to the termination depth of 4 m BGL.
Fill was only observed in borehole HA1 and was located on a garden bed on the southwest portion of the
site. The fill encountered is assumed to be uncontrolled. The fill material was generally consistent with the
aeolian soils, with the addition of occasional rootlets and organics.

5.3         Groundwater
Groundwater was not encountered in the boreholes during the investigation. Due to the relatively permeable
nature of the sand, prolonged periods of high groundwater or saturated soils are not anticipated except
following periods of high rainfall.

5.4         Surface Drainage
Surface drainage is anticipated to follow the natural contours of the land towards the south-west, with flows
directed into the roadside stormwater drainage system on Bottlebrush Avenue.

5.5         Vegetation
At the time of our investigation, site vegetation comprised short grass, shrubs and scattered large trees.
Densely vegetated areas (natural vegetation or garden beds) were concentrated in the south-west and north-
east portion of the site.

1
    GYMPIE SPECIAL 1:100,000 Geological Series. Map Sheet 9445 and Part 9545, First Edition, Department of Mines and Energy, Brisbane, 1999.



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