Appendix G - Geotechnical Report

Total Concept Homes                                                                            20332-001-Rev0
                                                                                             15 December 2020

3.0     ASSESSMENT OF LAND STABILITY
3.1   Existing Conditions
The crest area of the spur running south-west to north-east through the site, which incorporates the area of
the existing residence, and the proposed residence on the future subdivided allotment allotment has been
mapped by NC as presenting a Low/Very Low landslide susceptibility (clear/no shading). However the initial
flanks of the crest are mapped as a Moderate hazard area (pale yellow brown shading), which does cover a
part of the proposed building envelope for the future residence, and the driveway alignment. Towards the
inverts of gullies away from construction areas, High risk areas have been assigned (pale orange shading).
An extract of the NC mapping is given below in Text Figure 9.



                                                                                  Overall existing Lot boundary




Text Figure 9: 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largely based on ground slope, and is superseded by this site specific assessment.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 does not exhibit any indicators of global, natural slope instability. No landslide back scarps or
areas of natural ‘hummocky’ ground were observed, the existing structures on site were in good condition,
with no significant erosion or slumping observed over the existing access track alignment, or other minor
earthworks features (e.g. horticultural terraces). In addition the subsurface conditions were favourable
with stiff to very stiff soils present from surface, and weathered phyllite rock logged at relatively shallow
depth in both the boreholes and exposed in earthworks cuttings.

3.2   Qualitative Stability Assessment
The risk assessment for this project has been carried out following AGS 2007 Practice Note Guidelines for
Landslide Risk Management. Relative levels of risk and their implications are given in Table 1 on the
following page and the Qualitative Terminology for Use in Assessing Risk to Property is also attached.




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