Reference Document - MCU24/0143 (As Published)

        A further site visit was made by a principal geotechnical engineer from Tectonic on 27 May 2025, in order
        to assess the progression of the landslide activity following a period of prolonged and heavy rainfall.
        The results of the desk-top study, walk-over surveys, test pits and laboratory testing are summarised in
        Section 2 below.

        1.3           Qualifications of Responsible Engineer
        This report has been prepared by Ashley Davey, an RPEQ with more than 29 years of experience in
        geotechnical engineering, including numerous slope stability projects.


        2.            DESCRIPTION OF EXISTING CONDITIONS
        2.1           Geology
        A published geological map for the region1 indicates that the site is underlain by low grade meta-
        sedimentary strata forming the Triassic age Kin Kin Beds. Mapping also suggests that the ridge crest to
        the north-east of the site comprises a Tertiary age basalt ‘cap’ of ‘mostly olivine basalt flows and some
        plugs, some areas of nephelinite, basanite etc.’.




                                                              Approx. Site Location




                                         Text Figure 3: Extract from Gympie surface geology map

        Weathered phyllite of the Kin Kin beds was observed in driveway cuttings along the northern edge of the
        property. Phyllitic colluvium (historic landslide debris), was also observed in some of the cuttings around
        the existing cabins. Subsurface conditions encountered in the test pits are summarised as follows:
               Topsoil – friable, silty clay of high plasticity, typically about 100 mm thick; then
               Colluvium– stiff to very stiff, silty clay of high plasticity with varying gravel and cobble content to
                depths between 1.5 m and 2.2 m BGL; overlying
               Possible Residual Soil (test pit TP2 only) – very stiff, gravelly silty clay of high plasticity to 5 m BGL;
                then
               Extremely Weathered (XW) Materials/Weathered Phyllite – hard, gravelly clay and very low to
                medium strength phyllite. The phyllite rock mass was noted to be heavily fractured often forming



        1
            1:100,000 Gympie Surface Geology Map, Sheet 9445, 11 July 2018


        4 June 2025
        24378-001-Rev1                                                                                              3 of 12
Document Set ID: 24125427
                  24010296
Version: 1, Version Date: 17/09/2025
                          07/08/2025