Approved Document OPW18-0319 · OPW18/0319

                                                                                    Consult Arborist

5.9   TREE 9 – SWAMP MAHOGANY
 ID         Genus & Species                          Common Name
 9          Eucalyptus robusta                       Swamp Mahogany
 Height                    Crown Spread              [email protected]          Age
 12-14m                    8-10m                     500-600mm                Over-mature
 Health                                              Structure
 Fair to Poor with depleted canopy                   Fair to Poor with typical die-back in the main
                                                     branch structure
 Target                              Occupancy                        Target Zone
 Residential dwelling                Constant                         Within 1 x height & Dripline
 Comments
 Tree 9 is positioned adjacent to the retaining wall and structural root disturbance on the compression
 side is evident to facilitate the construction of the wall. With a canopy that favours the resort side,
 the tree has compensated by over-developing structural and buttress roots on the tension side that
 are visible at on the surface adjacent to the tree. This is a typical response for this species.

 With the upper canopy in a retrenchment state, there is an increase in twig/small branch dead wood
 and epicormic growth through the canopy. This is typical for this species and a natural method of
 reducing the canopy size at this stage of its life cycle.

 With no major faults noted that would indicate an increased likelihood of total failure within the
 timeframe of this assessment, the risk matrix has been calculated on branch failure as this has been
 deemed the most likely event to occur within the next 12 months.
 Likelihood of Failure           Likelihood of Impacting Target        Matrix 1 - Result
 Possible                        High                                  Somewhat Likely
 Consequence of Failure          Matrix 2 – Overall Risk Rating        Work Priority
 Minor                           Low                                   Proactive maintenance within
                                                                       6-12 months
 Recommendations

 While tree 9 is not deemed as a High-risk tree at this time there are options to undertake canopy
 management to assist the tree with its natural retrenchment process and reduce unpredictable
 branch drop while retaining the tree for future habitat value.

 •       Prune branches on dwelling side to reduce general encroachment and end-weight

 •       Re-inspect in 12 months.

 Residual Risk on completion of Mitigation Options
 LOW




19_01_24_TRA_RACV Resort _Noosa_V3                                                         Page 22 of 32