21054-001-Rev0 Tristania Dr

Peter Williams                                                                                             21054-001-Rev0
                                                                                                          25 February 2021

1.3        Qualifications of Responsible Engineer
This report has been reviewed by Mr Ashley Davey, an RPEQ with more than 25 years’ experience in
geotechnical engineering, including a number of slope stability projects


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




                                                                                  Approx. Site Location




Text Figure 3: Extract of Gympie Special geology map

The CSI investigation comprised two boreholes (designated BH1 and BH2) across the proposed
development area. These boreholes encountered relatively consistent subsurface conditions,
summarised as follows:

           Loose silty sand from the ground surface to 0.7 m below ground level (BGL); then
           Loose, poorly graded sand (borehole BH1) and medium dense poorly graded sand (borehole
            BH2) to the borehole termination depths (1.5 m BGL).

It should be noted that CSI continued dynamic cone penetrometer (DCP) testing beyond the borehole
termination depths, which indicated that the loose sands in borehole BH1 became medium dense below
about 3 m BGL.

Groundwater was not mentioned on the CSI borehole reports, with the soils described as ‘moist’.

CSI has classified the site as Class P, as per AS2870, due to poor bearing capacity; however, has
indicated that the soils encountered have the characteristics of a Class S site.




1
    Queensland Government, Department of Mines and Energy, 1:100,000 Gympie Special Geology Map, Sheet 9445 & Part 9545, 1999




                                                               3/11