Appendix B - Geotechnical Investigation Report

                                                TABLE A1: LANDSLIDE RISK ASSESSMENT
                              QUALITATIVE TERMINOLOGY FOR USE IN ASSESSING RISK TO PROPERTY (continued)
QUALITATIVE RISK ANALYSIS MATRIX – LEVEL OF RISK TO PROPERTY
                               LIKELIHOOD                                                   CONSEQUENCES TO PROPERTY (With Indicative Approximate Cost of Damage)
                                         Indicative Value of            1: CATASTROPHIC                 2: MAJOR                  3: MEDIUM             4: MINOR           5: INSIGNIFICANT
                                        Approximate Annual                    200%                          60%                      20%                    5%                    0.5%
                                             Probability
 A – ALMOST CERTAIN                              10-1                          VH                            VH                       VH                     H                  M or L (5)
 B - LIKELY                                      10-2                          VH                            VH                        H                    M                       L
 C - POSSIBLE                                    10-3                          VH                            H                        M                     M                      VL
 D - UNLIKELY                                    10-4                           H                            M                         L                     L                     VL
 E - RARE                                        10-5                          M                              L                        L                    VL                     VL
 F - BARELY CREDIBLE                             10-6                           L                            VL                       VL                    VL                     VL
Notes: (5)  Cell A5 may be subdivided such that a consequence of less than 0.1% is Low Risk.
       (6)  When considering a risk assessment it must be clearly stated whether it is for existing conditions or with risk control measures which may not be implemented at the current time.

RISK LEVEL IMPLICATIONS
                              Risk Level                                                                                    Example Implications (7)
                                                                         Unacceptable without treatment. Extensive detailed investigation and research, planning and implementation of treatment
             VH                          VERY HIGH RISK                  options essential to reduce risk to Low; may be too expensive and not practical. Work likely to cost more than value of the
                                                                         property.
                                                                         Unacceptable without treatment. Detailed investigation, planning and implementation of treatment options required to reduce
             H                             HIGH RISK
                                                                         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 regulator’s approval) but requires investigation, planning and
             M                          MODERATE RISK                    implementation of treatment options to reduce the risk to Low. 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 to this level, ongoing maintenance is
              L                             LOW RISK
                                                                         required.
             VL                          VERY LOW RISK                   Acceptable. Manage by normal slope maintenance procedures.
Note:      (7)     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.

Extract from PRACTICE NOTE GUIDELINES FOR LANDSLIDE RISK MANAGEMENT as presented in Australian Geomechanics, Vol 42, No 1, March 2007, which discusses the matter more fully.




February 2019