SUPERSEDED Compiled Reference Document - MCU24 0153 & OPW24 0202 (As Published)

        3.              Method of Investigation
        As part of our assessment, a desk-top study was carried out comprising a review of published geological
        maps, slope stability studies as well as Noosa Council (NC) planning overlays and site information.
        An experienced geotechnical engineer from Tectonic undertook a site walk-over on 6 September 2024 to
        visually assess any indicators of past slope instability. The walk-over included assessment of soil
        exposures, surface drainage conditions, topography, evidence of erosion or past instability, and
        vegetation coverage/condition.
        This was followed by a subsurface investigation comprising the drilling of four boreholes (designated
        BH1 to BH4) in accessible areas across the site. Borehole BH1 was drilled on the existing driveway
        toward the western boundary of the site using Tectonic’s 4WD mounted solid flight auger rig to a depth
        of 8 m below ground level (BGL). Due to access restrictions boreholes BH2 to BH4 were drilled using
        hand augering techniques to 3 m BGL to the north, east and south of the site. A further two boreholes,
        designated BH2A and BH2B were drilled to a depth of 1 m BGL to attempt to delineate rubbish
        encountered in the area during a previous soil test by another firm.
        In-situ testing, using the dynamic cone penetrometer (DCP) method, was carried out from the ground
        surface and within each borehole. DCP testing was extended below the base of the hand augered
        boreholes to depths between 4.5 m and 6.0 m BGL. Boreholes were backfilled on completion with
        drilling spoil, with excess material slightly mounded at surface.
        Laboratory classification testing was not warranted due to the sandy nature of the subsurface conditions
        encountered.
        Borehole locations are shown in Figure 1 attached at the end of this report, with borehole and DCP logs
        presented in Appendix A, together with explanatory notes. Subsurface conditions are discussed in
        Section 4.4. Borehole coordinates were recorded using a handheld global positioning system (GPS).
        The results of the desk-top study and walk-over survey are included in Section 4 below.



        4.              Results of Investigation
        4.1             Site Description
        The site is formally described as Lot 403 RP48112, covering an area of 755 m2, with frontage to Elanda
        Street to the west. At the time of the investigation a two-storey residential building occupied most of
        the western part of the site. The building was surrounded by at-grade concrete pathways and slabs with
        some garden spaces. Neighbouring properties consisted of two to three storey residential unit buildings
        to the north, east and south. An alleyway and drainage easement along the southern boundary provided
        pedestrian access between Elanda Street and Henderson Street to the east and also accommodated
        hydraulic services including stormwater and sewer mains.
        Inferred cut and fill earthworks had taken place across the site and adjacent areas. The site had been
        levelled with cut to fill earthworks up to about 2 m high supported by retaining walls along the northern
        and southern boundaries. Cut to fill estimated to be up to about 1 m was observed to form retained
        garden terraces.



        Proposed Unit Development
        30 September 2024 | 24265-001-Rev0                                                                        2
Document Set ID: 23376055
Version: 1, Version Date: 28/11/2024