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

October 2007                                   - 13 -                          077682076(AB)


5.6.4    Extrusion of ‘Marine’ Clays Adjacent Fill Areas

We anticipate that new fills will be constructed for the realigned golf tees in the south-western
part of the site. Investigations in those areas indicate soft clays up to approximately 1.5 m
thick. Provided that construction of new fill is staged and monitored, it is our opinion that
there should be a low probability of extrusion of ‘marine’ clays above the groundwater table.
Preloading of the site may be required together with settlement plate monitoring for any
building areas over soft clays. Preliminary geotechnical advice regarding filling of the site is
provided in Section 6.

5.6.5    Dewatering

All waters collected from groundwater or surface water inflow to excavations and runoff from
treatment areas should be collected in sumps and pumped to a treatment pond or tank for
monitoring and treatment to compliance with discharge criteria (if required) prior to release
from site.

6.0      GEOTECHNICAL ASSESSMENT

6.1     Subdivision Development

6.1.1   Earthworks

6.1.1.1 Site Preparation and Filling

Prior to any earthworks, organic rich topsoil must be stripped and removed from the
construction area. This material must not be used as fill to support any structural loads. Areas
of existing fill must also be excavated and re-placed in a controlled manner following the
guidelines below (eg. existing golf tees).

Dependent upon the natural ground conditions and prevailing weather at the time of
construction, areas of the exposed subgrade following surface stripping may comprise loose,
soft or saturated materials, particularly across the low-lying south-western part of the site. To
enable filling over such subgrades, it may be necessary to construct ‘bridging’ layers or over-
excavate and replace the unsuitable materials with select fill. Bridging layers can comprise a
combination of materials including geotextiles, clean gravel and rock ‘spalls’.

Following preparation of the subgrade, fill should be compacted at moisture contents within
the range of -2% to +0.5% of optimum moisture content for Standard Compaction.
Confirmatory testing must be carried out at regular intervals. A minimum of two tests per
300 mm vertical interval is recommended where structural fill heights are to exceed 300 mm.
Further details for control and testing of fill are given in Australian Standard AS 3798-2007
"Guidelines on Earthworks for Commercial and Residential Developments". Level 1
certification (as per AS3798) of earthworks is recommended for this site.




                                      Golder Associates