J001783-001-R-Rev1

Ashley and Caroline Hermes

Table 1: Stability Risk Levels
 Risk Level                            Example Implications(1)
                                       Unacceptable without treatment. Extensive detailed investigation and research, planning
 VH                VERY HIGH RISK      and implementation of treatment options essential to reduce risk to Low; may be too
                                       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
 M                 MODERATE RISK       investigation, planning and implementation of treatment options to reduce risk to Low.
                                       Treatment options to reduce to Low risk should be implemented as soon as practicable.
 L                 LOW RISK            Usually acceptable to regulators. Where treatment has been required to reduce the risk
                                       to this level, ongoing maintenance required.
 VL                VERY LOW RISK       Acceptable. Manage by normal slope maintenance procedures.
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.


The risk assessment essentially involves combining the elements of ‘Likelihood’ and ‘Consequence’ for the
potential hazards identified across the proposed development area in a qualitative manner. Relative levels of
risk and their implications are given in Table 2. It should be noted that the stability assessment above relates
to the global stability of the site. Our assessment does not include temporary/long-term stability of cut
excavations or permanent structural elements which are to be engineer-designed.
 Table 2: Qualitative Risk Assessment for Property (Based on AGS 2007).

                                                       Assessed
 Hazard              Likelihood    Consequence                        Comments
                                                         Risk


 Shallow failure                                                      Shallow slope instability as noted in the existing
 through                                                              landslides will have Insignificant impact on the residence
                       Likely       Insignificant         Low
 colluvium/                                                           provided that the recommendations in this report are
 residual soils                                                       implemented

 Failure
                                                                     The likelihood of a deep failure through the residual soil
 through
                                                                     and weathered rock is assessed as Unlikely due to the
 residual soil /
                                                                     apparent absence of deep-seated failures in this area,
 weathered
                    Unlikely         Medium                 Low      as well as the relatively low slope angles at the proposed
 rock below the
                                                                     residence and favourable discontinuity angles
 residential
                                                                     encountered in the test pits relative to the proposed
 footings or
                                                                     earthworks
 retaining walls
Refer Appendix B, Qualitative Risk Analysis Matrix (Australian Geomechanics Vol 42 No 1 March 2007).

Based on our assessment, it is our opinion that there is a Low Risk of global instability of the proposed
development, provided that the recommendations in this report are implemented. This level of risk is
normally acceptable to regulators.




J001783-001-R-Rev1