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

October 2007                                     - 14 -                           077682076(AB)


Select fill should have a maximum particle size of 100 mm for an uncompacted layer
thickness of 200 mm and shall be compacted by repeated rolling to achieve a dry density ratio
of at least 95% of the Maximum Standard Dry Density for cohesive soils, or 70% Dry Density
Index for cohesionless soils.

In accordance with good construction practice, fill embankments should be ‘over built’ and
then trimmed back to the well compacted material.

6.1.1.2 Settlements & Preloading

For future fills in the order of 2 m height in the south-western part of the site (eg. new golf
tees), we estimate total settlements from consolidation of soft ‘marine’ clays in the order of
90 mm for 1.5 m of total clay thickness. This estimate is for a design life of 50 years and is
based upon estimates of compressibility coefficients based upon local experience. It should
be noted that this settlement does not include the effects of building loads.

In order to minimise differential settlements for civil structures (eg. pavements and services)
and buildings, dependent upon the locations of such structures, it may be necessary to preload
fill areas. Based upon our experience in the local area, preload durations of up to 6 months
may be required. Preload durations and potential future creep settlements may be reduced by
the placement of additional fill (ie. surcharge) above the design fill level. Preloading
settlements must be monitored by settlement plates installed in the new fill.

It is essential that global stability issues are considered at the edges of preloaded areas prior to
the commencement of earthworks. It may be necessary to implement staged construction in
order to reduce the risk of global instability to an acceptable level.

In order to more accurately define likely settlements, preloading and staged construction
requirements, further detailed geotechnical investigation is recommended (Ref. Section 6.3),
once detailed subdivision design is available

6.1.1.3 Excavations and Batter Slopes

Excavations for road construction and underground services should be achievable using
conventional earthmoving equipment. The assistance of ripper attachments may be required
for excavation of the dense to very dense indurated sand, which was encountered below much
of the residential development area.

Temporary batters in clay, clayey engineered fill and indurated sand may be formed at 1V:1H,
and temporary batters in non-indurated sand should be no steeper than 1V:1.5H. Flatter
batters may be required if groundwater seepage is encountered or if batters are not protected
from erosion by rainfall.




                                       Golder Associates