Slope Stability Assessment

    unsealed driveway west of the residence pale orange brown, silty clay soils were exposed in some small
    erosion rills. This type of soil is analogous with the weathered materials of the Kin Kin Beds.
    The ASI ‘soil test’ comprised the drilling of four boreholes, denoted BH1 to BH4 around the perimeter of
    the proposed residence. Boreholes were drilled using a 4WD utility mounted, solid flight auger drill rig.
    The boreholes featured similar subsurface profiles, with up to 300 mm of topsoil logged at surface, then
    stiff, high plasticity clay to 1 m below ground level (BGL), followed by very stiff, silty clay to the borehole
    target depths of 3 m BGL (boreholes BH2 to BH4). Deeper probing was completed in borehole BH1 to
    5.8 m depth BGL, where “dense gravels” were noted on the log.
    Groundwater seepage was not mentioned in the ASI borehole reports, with the soils described as “moist.”
    ASI classified the site as Class M in accordance with AS2870, with a characteristic surface movement due
    to normal seasonal moisture variation (ys) only therefore of up to 40 mm.

    2.2           Topography
    Ground surface contours across the property and close surrounds are illustrated in Text Figure 4 below.



                                                                                    Lot boundary




                                                                            Central drainage line




Approx. stables                                Approx. proposed gym
       & arena
                            Approx. proposed residence


                       Text Figure 4: Topography of site and surrounds (courtesy Qld Globe)

    The site consists of an elongated shape, centred on a relatively wide valley. The valley has a head in the
    eastern part of the lot, and drains to the east/north-east. The ground slopes down from much higher
    ground off site to the north in to the central valley, however the proposed buildings would be located
    along the crest of a very gently defined, rounded spur crest. The spur trends to the east.
    Around the site of the proposed residence the crest area of the spur was >20 m wide, dipping to the east
    at about 4°. The southern flank of the spur was inclined at about 5°, and the northern flank ranged up to
    9°. The spur crest was wider around the proposed stables and arena, however it was noted that the
    southern edge of the building area dipped down at about 8°. Behind the existing residence, the upper


    13 February 2026
    26020-001-Rev0                                                                                          4 of 13