MCU14/0106 Appendix E - Engineering Report

August 2004 -10- 04682104(AB)

 

o™.

Based upon the laboratory test results, footings for one or two storey residential style buildings
(eg. for offices) may be designed using a preliminary site classification of ‘M’ in accordance
with Australian Standard AS2870-1996 “Residential Slabs and Footings”.

Heavy column loads from buildings or wind-loaded pylons (eg. for signage) may require
support by piled foundations. Our investigation results indicate that the most suitable piling
option is likely to comprise bored piles which socket into very stiff to hard clay or weathered
sandstone.

The founding depth for such piles will be dependent upon building loads and the variability in
stratigraphy over the piling depth. For preliminary design purposes, bored piles founded in very
stiff natural clay may be proportioned in accordance with an allowable end bearing pressure of
400 kPa and allowable side adhesion of 30 kPa. These values assume that the pile bases are
cleaned of any loose or water-softened material and that there is intimate contact between the
pile shaft and foundation. Side adhesion should be neglected for the upper 1.5 m length of
socket (below ground level).

At the completion of bulk earthworks, it is recommended that Golder Associates should carry
out further investigation of the proposed building areas in order to confirm the advice given
above for conventional (ie. high level) footings. This would comprise inspection by an
experienced Geotechnical Engineer together. with borehole probing (4WD auger rig), DCP
testing and laboratory Shrink-Swell testing.

6.4 Preliminary Pavement Design

Design parameters for pavements will be dependent upon the ‘subgrade materials present after
earthworks and the type, depth and quality of new fill used to bring the site to design levels.
The test pit / borehole and laboratory test results from this site indicate that the subgrade
materials exposed/formed following earthworks may vary dependent upon the location. CBR -
values assessed from the results of this investigation, and from previous experience, are
provided in Table 2. It should be noted that these values assume that the subgrade is well
drained during construction and operation.

Golder Associates