Approved Document OPW24-0047 Noosa Springs Golf & Spa Resort Turf & Vegetation Management Plan 2024-25

 A PPENDIX 2: T REE R ISK A SSESSMENT M ETHODOLOGY
 The methodology of rating risk used in this report is based on the following International Society of Arboriculture’s Tree Risk
 Assessment and is calculated using qualitative risk matrix tables.

 Initially, the Likelihood Matrix is used to estimate how likely a failure will be to impact a target. This is calculated by categorising
 how likely failure is to occur and combining that with how likely that failure is to impact a target, as per Table 1.

                                                               Matrix 1 – Likelihood Matrix (M1)
                                                                             Likelihood of Impacting Target
 Likelihood of Failure
                                              Very low                        Low                   Medium                High
        Imminent                              Unlikely                  Somewhat Likely               Likely            Very likely
        Probable                              Unlikely                      Unlikely             Somewhat Likely          Likely
         Possible                             Unlikely                      Unlikely                 Unlikely         Somewhat Likely
       Improbable                             Unlikely                      Unlikely                 Unlikely            Unlikely
 Table 1: Matrix 1 – Level likelihood of impact to a target.

 Once the Likelihood of Failure & Impact level is determined a final level of Risk Rating can be calculated by combining the
 Likelihood with the Consequences of Failure for each identified risk. This ascertains an overall Risk Rating for the tree, determined
 in Table 2.

                                                                   Matrix 2 – Risk Rating Matrix (M2)
 Likelihood of Failure                                                      Consequences of Failure (CoF)
       & Impact                              Negligible                      Minor                 Significant             Severe
      Very Likely                              Low                         Moderate                   High                Extreme
         Likely                                Low                         Moderate                   High                  High
   Somewhat Likely                             Low                            Low                   Moderate              Moderate
        Unlikely                               Low                            Low                     Low                   Low
 Table 2: Matrix 2 – Level of Risk

 Where multiple risks are noted, these tables will be used for each risk and the highest level will be taken as the overall risk rating
 for the tree. In this scenario, multiple mitigation options may be offered to the tree manager to return the risk to an acceptable
 level within a reasonable timeframe as guided in Appendix 1.


 A PPENDIX 3: D EFINITION OF ISA T ERMS
Likelihood of Failure
Improbable: The tree or branch is not likely to fail during normal weather conditions and may not fail in many severe weather
               conditions within the specified time frame.
Possible:      Failure could occur, but it is unlikely during normal weather conditions within the specified time frame.
Probable:      Failure may be expected under normal weather conditions within the specified time frame.
Imminent:      Failure has started or is most likely to occur in the near future, even if there is no significant wind or increased load.
               This is an infrequent occurrence for a risk assessor to encounter and may require immediate action to protect people
               from harm.
Likelihood of impacting a target
Very low:      The likelihood of the failed tree or part impacting the specified target is remote. Occupancy rates are rare with no
               protection or occasional with moderate protection.
Low:           It is not likely that the failure will impact the target. The occupancy rates are frequent with partial protection or constant
               with significant protection.
Medium:        The failure is as likely as not to impact the target. The occupancy rates are frequent with single-side exposure or
               constant with partial protection.
High:          The failure is most likely to impact the target. Occupation is constant with no protection.
Occupancy rates (OR)
Constant:      24 hours a day, 7 days a week.
Frequent:      A large portion of the day/week.
Occasional: The zone is occupied by people or targets infrequently or irregularly.
Rare:          Not commonly used.
Consequences of Failure
Negligible:    Low-value property damage or disruption that can be replaced or repaired, no personal injury.
Minor:         Low to moderate property damage, small disruptions to traffic or infrastructure, or very minor injury to persons.
Significant:   Property damage of moderate to high value, considerable disruption, or personal injury.
Severe:        Serious personal injury or death, damage to high-value property or disruption of important activities.
Levels of risk
Extreme:       Failure is imminent with a high likelihood of impacting the target, and the consequences are severe.
High:          Failure is very likely or likely with significant consequences, or failure is likely with severe consequences.
Moderate:      Failure is very likely or likely with minor consequences, or failure is somewhat likely with significant or severe
               consequences.
Low:           Failure is unlikely with negligible consequences or failure is somewhat likely with minor consequences.




 24_06_10_VTA_Noosa Springs Golf Course_1                                                                                 Page 29 of 35