Slope Stability Report-21190-001-Rev0 Pomona Kin Kin Rd

Phil Brierley                                                                                           21190-001-Rev0
C/- NDD Constructions Pty Ltd                                                                              21 June 2021

It should be noted that the NC map is a broad-scale indication of the potential landslide susceptibility and
is superseded by this site-specific assessment. In the vicinity of the proposed shed and workshop there
were no signs of global slope instability. Very low to medium strength argillite/phyllite were observed in
the cuttings on the upslope side of the development areas and along the existing driveway.

Based on review of available aerial imagery, it appears that the building platform at the proposed shed
site has been in place for over five years. Nevertheless, it should be noted that the fill platforms are
deemed to have been placed as uncontrolled fill, therefore, it is possible that zones within this fill may be
unsuitable, and that excessive settlement could occur over time, particularly following construction of non-
piled structures (e.g. landscaping structures, pavements etc.). Without verification that this fill was placed
under Level 1 inspection and testing per AS3798, the potential magnitude and extent of settlement within
this fill will be unknown.

3.2   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 below, and
the Qualitative Terminology for Use in Assessing Risk to Property is also attached.
 Table 1: Stability Risk Levels

 Risk Level            Example Implications(1)
                       Unacceptable without treatment. Extensive detailed investigation and research, planning
       Very High
 VH                    and implementation of treatment options essential to reduce risk to Low; may be too
       Risk
                       expensive and not practical. Work likely to cost more than value of property.

                       Unacceptable without treatment. Detailed investigation, planning and implementation of
 H     High Risk       treatment options required to reduce risk to Low. Work would cost a substantial sum in
                       relation to the value of the property.
                       May be tolerated in certain circumstances (subject to regulators’ approval) but requires
       Moderate
 M                     investigation, planning and implementation of treatment options to reduce risk to Low.
       Risk
                       Treatment options to reduce to Low risk should be implemented as soon as practicable.
                       Usually acceptable to regulators. Where treatment has been required to reduce the risk
 L     Low Risk        to this level, ongoing maintenance required.
       Very Low
 VL                    Acceptable. Manage by normal slope maintenance procedures.
       Risk
 Note: (1) The implications for a particular situation are to be determined by all parties to the risk assessment and may
 depend on the nature of the property at risk; these are only given as a general guide.

Considering the existing site conditions (Ref. Section 2), and subject to the implementation of
recommendations given below, it is assessed that there would be a Low (L) Risk of global slope instability
affecting the proposed development. Regulators (NC) normally require that a Very Low or Low Risk of
landslide affecting the property must be demonstrated to enable development approval. Summarised in Table
2 overleaf, is our qualitative assessment of landslide risk for the site. A summary of qualitative terminology
for use in assessing risk to property is attached (taken from AGS 2007).

It should be noted that this risk assessment excludes geotechnical risk that may be associated with settlement
due to consolidation of any uncontrolled fill materials over time which could affect non-piled structures (e.g.
pavements, landscaping structures).




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