Appendix G - Geotechnical Report

Total Concept Homes                                                                                      20332-001-Rev0
                                                                                                       15 December 2020

Table 2: Details of Qualitative Risk Assessment for Property (AGS 2007
                                                              Assessed
 Hazard                            Likelihood   Consequence
                                                                Risk
                                                                         Comments

                                                                         The driveway alignment exploits an existing track in
                                                                         some parts, and although the central portion of the
                                                                         driveway is proposed sidelong to a moderately
                                                                         steep slope; given the presence of stiff to very stiff
                                                                         residual soils and XW materials from surface, no
 1: Proposed driveway -                                                  evidence of existing instability (including relatively
shallow failure through existing                                         good performance of existing fill embankments),
natural soil materials (fill        Unlikely       Minor          Low    apparent lack of shallow groundwater, and the
subgrades or earthworks cuts);                                           proposed engineer designed retention of future fill
or future fill materials                                                 for the driveway, it is considered Unlikely that a
                                                                         landslip would develop, subject to implementation of
                                                                         the recommendations in Section 4 (e.g. foundations
                                                                         levels and fill quality). Given a potential Medium
                                                                         impact from such shallow instability the resultant risk
                                                                         would be Low as per AGS 2007.



                                                                         Given the presence of stiff residual soils at surface,
                                                                         and stiff to very stiff XW materials below at shallow
                                                                         depth, the rounded nature of the spur crest where
                                                                         construction is proposed, and negligible catchment
 2: Proposed residence on
                                                                         for water above the site and apparent lack of
subdivided Lot - Failure
                                                                         groundwater, and no evidence of existing instability
through natural soils or XW         Unlikely      Medium          Low
                                                                         in the vicinity of the proposed residence, it is
materials above the foundation
                                                                         considered Unlikely that a landslip would develop,
depth
                                                                         subject to implementation of the recommendations
                                                                         in Section 4. With a potential Medium impact from
                                                                         such shallow instability the resultant risk would be
                                                                         Low as per AGS 2007.




                                                                         The likelihood of a deep failure through the weathered
                                                                         phyllite rock below the foundation depth is assessed
 3: Proposed residence on
                                                                         as Barely Credible due to the strength of these
subdivided Lot, or proposed
                                    Barely                               materials, no evidence of existing instability, and
driveway alignment - Deep                          Major      Very Low
                                   Credible                              relatively consistent nature of the sloping ground
seated failure in weathered rock
                                                                         across the development area. Although the
below the foundation depth
                                                                         consequence of such a failure could be Major, the
                                                                         resultant risk is Very Low as per AGS 2007.




The potential impacts on slope stability of the development components have been assessed, and the
measures recommended below in Section 4 have been designed to mitigate those impacts.




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