Reference Documents - MCU23 0070

Cambooya Pty Ltd

Re-compaction of materials should be undertaken under ‘Level 1’ inspection and testing as detailed in
Australian Standard AS3798-2007 Guidelines on Earthworks for Residential and Commercial Developments.
Working platform assessments must be undertaken by a suitably qualified person (i.e., RPEQ geotechnical
engineer) for large plant (e.g., cranes).


6.1.2 Temporary Batter slopes
Temporary unsurcharged batters in loose to very dense sand up to 3 m vertical height should not be formed
steeper than 1V:3H. Flatter batters may be required if localised instability or groundwater is encountered
during construction.


6.1.3 Excavatability
Cut excavations of up to about 3 m high are anticipated. Excavations within this depth range should be
achievable with small to medium earthmoving equipment (i.e., 8 to 12 tonne excavators). Larger machinery
will however improve production rates. Depending on the strength of cementation of the exposed indurated
sand (i.e., coffee rock), ripping attachments may be required.


6.2     Foundations

6.2.1      Footing Design
Conventional high-level strip and pad footings could be considered to support the proposed building,
however, where footings are located along the east and west boundaries adjacent to existing structures,
footings will need to be founded below the zone of influence of these structures. It is recommended that
additional investigation be undertaken prior to construction, to assess foundation depths of the adjacent
structures. It is likely that foundations along the east and west boundaries will require the use of a contiguous
piled system (refer Section 6.3).
Where high-level strip or pad footings are able to be adopted, these should be founded at least 0.4 m into
the underlying very dense sand, designed using an allowable bearing pressure of 400 kPa.
Footing settlements would not be expected to exceed around 1 % of footing width for pads and strips, under
serviceability loads.
Piles could comprise bored piers or continuous flight auger (CFA) piles. Liners may be required for bored
piles to prevent the upper loose to medium dense sands from caving in. The use of driven piles (including
sheet piles) is not considered suitable due to vibrational impacts on the surrounding structures.
Bored or CFA piles founded in the underlying very dense sand could be designed using an ultimate bearing
pressure of 1.5 MPa, and ultimate skin friction of 70 kPa.
A geotechnical engineer must confirm the design bearing pressures during construction. Footing excavations
must be dry and cleaned of any loose, disturbed, or saturated materials prior to pouring concrete.
If any soil conditions encountered during the footing excavations are found to differ from those noted in the
geotechnical investigation, Core should be notified immediately, and an assessment of the footing
excavations should be carried out to assess if changes to footing design are required.
All footings should found such that they are not adversely affected by any adjacent excavations, batter
slopes, trenches, or retaining walls that are not designed to support building or fill loads.
To minimise the potential for any adverse interaction effects, footings should found at least below a plane
extending 1 m horizontally from the base of trenches/batter slopes/excavations/retaining walls, then rising up
at 1V:1H. This requirement is illustrated in the following diagram.




J001873-001-R-Rev1                                                                                   Page 6