4895-Geotech Assessment

Mr Max Richardson                                                                             20362-001-Rev0
C/- Long View Consulting Engineers Pty Ltd                                                       28 July 2021

3.0     ASSESSMENT OF LAND STABILITY
3.1    Existing Conditions
The proposed house site and most of the proposed driveway alignment have been mapped by NC as
presenting no landslide hazard (presumably Very Low or Low Hazard areas), however the south-eastern end
of the proposed driveway partly traverses a Moderate hazard area (pale yellow brown shading). An extract
of the NC mapping is given below in Text Figure 8.

                                           Proposed house site




                                                                     Existing track




Text Figure 8: Extract from NC Landslide Hazard Mapping

It should be noted that the NC map is a broad-scale indication of the potential landslide susceptibility only,
largely based on ground slope, and is superseded by this site-specific assessment.

The site did not exhibit any indicators of global, natural slope instability. No landslide back scarps,
tension cracks in the ground surface or areas of natural ‘hummocky’ ground were observed at or near the
proposed house site and driveway alignment. Exposed geology consists of shallow residual clay soils
overlying meta-sedimentary phyllite, which is not known for the development of extensive slope instability
in the region. Topography and drainage across the proposed development areas was favourable. A 2015
aerial photograph obtained from the NC Interactive Maps website (Ref. Text Figure 9) does show possible
small landslide features on steep ground near the gully floor to the south of, but well down slope from, the
proposed house site. These likely landslides are sufficiently setback from the proposed house site and
driveway so as to pose a negligible risk to the proposed development.
                                            Proposed house site




                          Possible landslide features




Text Figure 9: 2015 aerial image courtesy of NC Interactive Maps




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