Reference Documents

                                                  PROPOSED SUBDIVISION
                                                  41 TALLOWWOOD PLACE, BLACK MOUNTAIN

            4.3           Geology
            The 1:100,000 scale Gympie Surface Geological Map 2 (Ref. Text Figure 9) indicates that the site is underlain
            by materials derived of the early to middle Triassic age Kin Kin Beds (blue-green shading), which are
            described as “commonly cleaved and commonly kinked mudstone…”. The Australian Stratigraphic Units
            Database describes the Kin Kin Beds as “arenite, argillite and phyllite.”




                                                                                      Indicative Site Location




            Text Figure 9: Extract from Gympie Surface Geology Map

            4.4           Subsurface Conditions
            Detailed descriptions of the subsurface conditions encountered in the test pits are provided in the reports
            attached in Appendix A, along with definition sheets which describe terms and abbreviations used on the
            reports. Subsurface conditions encountered across the proposed new development area (i.e. test pits TP1,
            TP3 and TP4) were consistent summarised as follows:
                        Topsoil/Fill – comprising friable silty clay of medium plasticity, with varying organic, gravel and
                         cobble content to depths between 0.3 m and 0.6 m BGL; then
                        Residual Soils – very stiff to hard, silty clay of high plasticity and clayey silt of high liquid limit to
                         depths between 1 m and 1.2 m BGL; underlain by
                        Extremely Weathered (XW) Materials/Weathered Phyllite – hard, silty gravelly clay of medium
                         plasticity and very low strength phyllite, rapidly grading to low strength (or stronger), with toothed
                         bucket refusal or very slow digging achieved at depths between 1.7 m and 2.3 m BGL.

            Test pit TP2 was excavated on the proposed driveway alignment, downslope of the rock fill embankment
            (inferred remediated landslide) and encountered a friable topsoil layer to 0.3 m BGL, then a stiff to very stiff,
            silty gravelly clay of high plasticity, being colluvium 3/landslide debris, with fissured and slickensided 4
            surfaces to 3 m BGL (limit reach of the machine). Based on our site observations this area appeared to
            have been impacted by previous landslide movements.

            Text Figure 10 overleaf illustrates typical subsurface conditions encountered during the investigation.


            2
                State of Queensland, Dept. of Natural Resources, Mines and Energy, Gympie Surface Geology, Sheet 9445, 2018
            3
                A mixture of soil and/or rock (of various sizes) deposited over geological time due to movement induced by gravitational force
            4
                A smooth, often striated surface produced by movement along a plane of weakness within soil or rock


             22 May 2023
             Report No. 23099-001-Rev0                                            7

Document Set ID: 22826802
Version: 1, Version Date: 23/02/2024