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

        Executive Summary
        This report details the results of a geotechnical investigation undertaken for the proposed residential unit
        development at 17 Bottlebrush Avenue, Noosa Heads. The investigation was performed by Tectonic for
        Made One Pty Ltd. Recor are the structural consultants and project managers for the build.
        The investigation comprised drilling of boreholes at two locations across accessible areas of the
        development footprint. This report summarises the results of the investigation and provides
        geotechnical recommendations regarding earthworks and footings, together with temporary and
        permanent basement retention.
        Preliminary architectural drawings indicate that the development will comprise a three-storey unit
        building, over a single level basement carpark. Construction will include a combination of masonry and
        lightweight materials, suspended concrete floors, and pools on both the second level and roof. No
        earthworks details were provided at the time of reporting; however, the plans indicate that excavations
        for the basement would likely be in the order of about 5 m deep to the rear, with the cut daylighting at
        the front. Localised filling of less than 1 m high is anticipated. Excavations will extend close to the site
        boundaries and, therefore, some form of temporary retention will likely be required. Isolated deeper
        excavations may be required for the lift overrun pit and other elements.
        The subsurface conditions encountered in the boreholes are summarised as follows:
             Topsoil – comprising very loose to loose organic sand, to 0.1 m below ground level (BGL); then
             Fill – comprising loose sand, to depths of between 0.7 m and 1.1 m BGL; with underlying
             Natural Sands – comprising poorly graded sands, mostly being loose to depths of between 1.2 m
              and 1.7 m BGL; then becoming medium dense and increasing to dense below depths of between
              3.2 m and 3.6 m BGL.
        No signs of groundwater seepage (‘springs’) were observed during our walk-over. Groundwater was not
        encountered in the boreholes at the time of investigation.
        Provided the recommendations within this report are adhered to, and subject to detailed design and
        construction of the footing and retention systems by a suitably qualified and experienced RPEQ
        structural engineer, there should be a Low Risk to the proposed development from slope instability.
        Excavations through the soils encountered should be achievable using conventional earthmoving plant
        (e.g. excavators with toothed buckets). Temporary, unsurcharged cuts in the very loose to loose sands
        could be formed at 1V:2H, and at 1V:1.5H in medium dense (or denser) sand, for batters up to 3 m in
        height, provided groundwater seepage is not encountered and sands do not slough from the batter face
        as they dry out. It is expected that space restrictions will limit battering of temporary cuts on the site and
        so some form of temporary retention system will be required (e.g. sheet or secant piles).
        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.
        Given the sandy soil profile, where deepened footings are required away from cut areas, steel screw piles
        are considered to be a suitable foundation type. Due to the presence of loose sands, together with the
        close proximity of adjacent residences, open bored piers or driven piles are not considered to be suitable
        for this site.


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