Reference Document - MCU26 0001 & OPW26 0002 - AS PUBLISHED · MCU26/0001

        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 half the width of the compaction equipment (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.
        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 from shallow depths. If
        not for this factor, the site would have the characteristics of Class S, with the estimated characteristic
        surface movements (‘ys’) ranging up to about 20 mm. However, 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 slabs, footings 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 of about 1.3 m BGL (existing ground levels) in the boreholes.
        High-level footings or locally deepened pads could be utilised in most areas of cut, whilst piles would be
        required elsewhere.
        High level footings, where achievable in 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. Excavations
        would likely loosen the sands, so densification of high-level footing bases should be allowed for, by
        compaction with a vibrating plate, prior to placement of steel reinforcement.
        Piles founded in medium dense (or denser) sands may be designed using an allowable end bearing
        pressure (ABP) of 400 kPa. Should higher bearing pressure be required, deeper piles founded at least 1 m
        into dense (or denser) sand (about 5 m BGL) could be designed using an ABP of 1 MPa.
        Given the sandy soil profile, where piles are required, steel screw piles would commonly be adopted.
        Due to the presence of loose sands, together with the close proximity to surrounding infrastructure, open
        bored or driven piles are not considered to be appropriate for this site. Steel reinforced concrete bored
        piles could be feasible; however, the use of sacrificial liners (e.g. ‘formatube’) would be required to
        prevent the caving of upper loose sands. Grout-injected, continuous flight auger (CFA) piles could also


        Geotechnical Investigation
        30 January 2026 | 25408-001-Rev0                                                                             13
Document Set ID: 25158026
                  24528612
Version: 1,
         2, Version Date: 10/09/2026
                          13/02/2026