MCU25 0087 - Reference Document - Geotech assessment report (As Published) · MCU25/0087

        should be graded to ensure free drainage of stormwater away from construction areas, and to a control
        point(s).

        6.1.2           Excavations
        Excavations through the soils should be achievable using conventional earthmoving plant
        (e.g. excavators with toothed buckets). Temporary, unsurcharged cuts in the very loose to loose sand
        could be formed at 1V:2H, and at 1V:1.5H in medium dense (or denser) sand, for batters up to 4 m in
        height. Flatter batters or temporary retention may be required if groundwater seepage is encountered or
        if sloughing of dry sand occurs at the batter surface. Deeper cuts, if required, may require temporary
        shoring, unless assessed and approved by Tectonic during construction.
        Permanent cuts or fills greater than 1 m must be retained. Permanent cut and fill batters up to 1 m high
        shall not exceed 1V:2.5H. Any permanent soil and fill batters will require erosion protection (e.g.
        revegetation or surface protection).
        It is likely that the temporary batter slopes will not be able to be achieved due to spatial constraints.
        Thus, temporary shoring will likely be required, as per the recommendations in Section 6.3 below.
        Excavations in close proximity to existing structures and infrastructure (e.g. underground services in
        along the eastern property boundary), including neighbouring properties, will need to be specifically
        designed to prevent undermining. If undermining is a potential issue the existing structures may need to
        be underpinned or excavations may require temporary shoring.
        The advice of a suitably qualified and experienced structural RPEQ must be sought regarding any
        potential undermining and design and construction of any underpins/temporary shoring (if required).
        The above recommendations do not supersede any existing safety regulations or legislation applicable to
        excavations (e.g. limits on personnel entry into trenches).

        6.1.3           Filling
        The natural sandy soils where free of deleterious materials (e.g. vegetation, organics etc.) may be reused
        as structural fill, subject to appropriate moisture adjustment. It should be noted that compaction of such
        relatively ‘clean’ sands as structural fill requires the addition of substantial volumes of water (‘flooding’)
        combined with the use of vibratory compaction equipment (typically a smooth drum roller or heavy
        vibrating plate). Should importation of fill be required, it is recommended that such fill should comply
        with the following:
             Minimum CBR of 10 %
             Maximum plasticity index of 15 %
             Shrink-swell index ≤ 1 %
             Maximum particle size of 100 mm
        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



        Geotechnical investigation
        19 November 2025 | 25289-001-Rev0                                                                           18
Document Set ID: 24631529
Version: 1, Version Date: 24/03/2026