Appendix 5. Geotechnical Engineering Report [As Published] · 132007.2399

October 2007                                     -i-                            077682076(AB)


                                 EXECUTIVE SUMMARY

Starco Developments Pty Ltd has commissioned Golder Associates Pty Ltd (Golder) to
conduct a preliminary ASS and geotechnical investigation for a proposed residential
development described as Precinct J at Noosa Springs. The proposed works include a 27 lot
residential subdivision and realignment of the 18th hole golf tees to the south-west. This
report presents the results of the investigation together with preliminary comments and advice
regarding ASS and geotechnical matters.

A preliminary investigation was conducted because details regarding earthworks and building
development were not known at the time of reporting.

The site covers an area of about 3.06 ha, mostly comprising gently sloping ground ranging in
elevation from about RL 9 m (east) to RL 1.5 m (west, south-west). The site mostly
comprises a palm plantation surrounded by the Noosa Springs Golf Course.

The investigation comprised eight boreholes drilled to depths of between 3 m and 6 m, with a
number of samples recovered from two of the boreholes used for ASS testing.

Following the field and laboratory work, the results were used to assess the extent of ASS,
together with measures for environmental management during construction, and a number of
geotechnical issues. Summarised below are the investigation findings and recommendations:

•   The western part of the site is underlain by mostly medium dense to dense sands or denser
    indurated sands (‘coffee rock’).
•   Swampy deposits including up to 1.5 m thick soft ‘marine’ clays occur in the south-
    western part of the site, overlying stiff residual clays.
•   Groundwater seepage typically occurs at depths of between 1 m and 1.5 m.
•   Potential Acid Sulfate Soil (PASS) exist within natural materials in the south-western part
    of the site, with the ‘marine’ clays being high level PASS.
•   Lime treatment is required at varying rates for material that will be excavated from the
    site, ranging from 10 kg/m³ for fill and pale coloured natural soils up to 100 kg/m³ for the
    soft ‘marine’ clay.
•   The construction of ‘bridging’ layers and/or excavation and removal of unsuitable
    materials will likely be required for fills in the south-west.
•   Dependent upon the final locations of buildings, preloading and/or piling may be required
    where soft clays occur.
•   In general, future site classifications are anticipated to be ‘S’ for residential construction
    (based on the natural soil profiles).
•   Higher site classifications are probably in areas underlain by soft ‘marine’ clay.




                                      Golder Associates