Reference Document - MCU25 0060 (As Published)

Any fill should be compacted at moisture contents within the range of ±2% of optimum moisture
content for Standard Compaction. Fill material should be placed in 250 mm thick (loose thickness) layers
and be compacted by repeated rolling using a minimum 4 tonne smooth drum roller (or equivalent, with
vibration on if safe to do so) to achieve a dry density ratio of at least 95 % of the maximum Dry Density
Ratio (DDR), based upon the Standard Compaction method, or a Dry Density Index of at least 70 %.
Confirmatory compaction testing must be carried out at regular intervals. A minimum of two tests per
vertical lift 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.
Fill embankment edges must be over-filled by 0.5 m (horizontally) and then trimmed back to well
compacted material.


6.3          Building Foundations
6.3.1        Indicative Site Classification
Site classifications for footing design are determined in accordance with AS 2870-2011 Residential Slabs
and Footings, and depend on the depth of cut / fill undertaken at a site, variations in the natural soil/rock
depths, and the reactivity of the in situ soil / rock and any imported fill materials. It should be noted that
the proposed works are outside of the scope of AS2870.
Based on the results of the investigation, the site is classified as Class P in accordance with AS 2870-2011
Residential Slabs and Footings, due to the presence of poor bearing capacity soils at shallow depths.
However, if not for these factors, the site would have the characteristics of Class S, with the estimated
characteristic surface movements (‘ys’) ranging up to about 20 mm. Due to the potential variability in
subgrade density a site classification of Class M is recommended in relation to assessment of flexibility
requirements for ground slab, footing and plumbing design.

6.3.2        Footing Design
No design loadings were available at the time of reporting. Footings for the proposed development and
any ancillary structures (e.g. retaining walls, etc.) must penetrate through any unsuitable natural soils (i.e.
very loose to loose sands) to found at least 0.5 m into medium dense (or denser) natural sands. Such
materials were encountered below depths between about 1.1 m and 1.3 m BGL (existing ground levels) in
the boreholes. Thus, it is expected that a combination of high-level footings (e.g. in areas of deeper cut)
and locally deepened pads, possibly ranging to piles in uncut or filled areas.
High level footings, where achievable in deeper cut areas, may be designed using an allowable bearing
pressure of 100 kPa provided that they are founded in the natural medium dense (or denser) sands. Piles
founded in medium dense (or denser) sands may be designed using an allowable end bearing pressure of
600 kPa. Settlement under such loads is expected to be in the order of up to 20 mm or 1% of footing
width.
It should be noted that excavation for concrete strip footings (or similar) may loosen the base. Therefore,
the use of a vibrating plate and ample water would be required to densify any high-level footing bases
prior to the placement of reinforcing steel.
Due to the presence of loose sands, open bored piers or driven piles are not considered to be suitable
for this site. Steel reinforced concrete bore piles may be possible; however, the use of casings or


Proposed Residential Development
25 August 2025 | 25038-001-Rev0                                                                              15