Geotechnical Investigation Report

                                        PRACTICE NOTE GUIDELINES FOR LANDSLIDE RISK MANAGEMENT 2007
                APPENDIX C: – 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:
                                          Approximate Annual                 200%                         60%                      20%                     5%                INSIGNIFICANT
                                              Probability                                                                                                                         0.5%
A –    ALMOST CERTAIN                              10-1                          VH                         VH                      VH                       H                   M or L (5)
                                                     -2
B -    LIKELY                                      10                            VH                         VH                       H                       M                       L
C -    POSSIBLE                                    10-3                          VH                          H                       M                       M                      VL

D -    UNLIKELY                                    10-4                           H                         M                        L                       L                      VL
                                                     -5
E -    RARE                                        10                             M                          L                       L                      VL                      VL
                                                     -6
F -    BARELY CREDIBLE                             10                             L                         VL                      VL                      VL                      VL
      Notes:    (5)   For 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.
                                                                  Acceptable. Manage by normal slope maintenance procedures.
           VL                     VERY LOW RISK

       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.




      92                         Australian Geomechanics Vol 42 No 1 March 2007