Works Committee Meeting
Telephone: 02 9399 0999 or
1300 722 542 (for
Fax:02 9319 1510
8 July 2008
Works Committee Meeting
Notice is hereby
given that a Works Committee Meeting of the Council of the City of
Quorum: Five (5) members.
Apologies/Granting of Leave of Absences
Confirmation of the Minutes
Works Committee Meeting -
Declarations of Pecuniary and Non-Pecuniary Interests
Address of Committee by Members of the Public
W16/08 Council-Owned Ficus
'Hillii' (Hill's Weeping Fig) Outside
Notice of Rescission Motions
8 July 2008
Works Report No. W16/08
Ficus 'Hillii' (Hill's Weeping Fig) Outside
Folder No: F2004/07359
On the morning of 12 June 2008, I attended an on-site meeting with Council’s plumber to assess a sewer blockage and associated damage caused by the roots of a large Council-owned Ficus ‘Hillii’ (Hill’s Weeping fig) growing on the nature strip outside that property.
Council’s plumbers have attended to sewer blockages within the subject property on a number of occasions and the latest blockage has necessitated the excavation of an area surrounding the external boundary trap that accesses the property.
This excavation has revealed that roots from the adjacent fig tree have completely encased the sewer system and have not only blocked the pipes, but have actually dislodged them as well. There is also a gas pipe into the property that has also been completely encased by tree roots.
The boundary trap and sewer pipes into the property are located less than two metres from the trunk of the subject tree.
To exacerbate the situation even more, there is a bedrock shelf running under the tree and surrounding area that is only 500mm below ground level and the boundary trap and sewer pipes have had to be laid in a channel carved out of sandstone.
This also means that the tree is situated on a very shallow rock shelf and that its roots have very little depth to actually facilitate support of the tree.
The plumber has excavated as much as he can without major tree roots being severed and it was at this point that I was requested to inspect the tree.
The tree is in reasonable health and is approximately ten metres tall with a canopy spread of between ten-twelve metres. It is growing under overhead powerlines and adjacent to domestic service wires and has to be regularly pruned to maintain the statutory clearances from these wires.
The tree forms part of an important avenue of Ficus ‘Hillii’ street trees that are 50-60 years old and which are characteristic of parts of the Randwick LGA.
Several of this tree species have had to be
removed along the length of
The subject tree has been assessed as having a moderate risk potential. It has also been assessed as having a medium hazard rating when issues such as failure potential, target rating and the size of any potential branch failures are considered.
It has been acknowledged as having important scenic/environmental amenity and as providing habitat/food source for a variety of native fauna and birdlife. Conversely, any effect of removal on soil stability/land degradation would be negligible.
The tree has been assessed by a Council tree officer as having an amenity value of $10,800 – using the Standards Australia AS – DR99307 valuation guide.
Relationship to City Plan
The relationship with the City Plan is as follows:
Outcome: A Healthy Environment.
Direction: Risks and impacts are strategically managed.
Key action: Implement policies, programs and strategies to manage environmental risks and impacts.
Financial impact statement
The total cost to remove and stump grind the subject tree and to re-instate the surrounding nature strip, footpath and adjacent infrastructure would be approximately $3,000 and this would come from Council’s annual tree management budget.
This species of tree is entirely inappropriate for growing in a confined nature strip situation such as this, immediately adjacent to public infrastructure and private property.
The footpath adjacent to the property has been uplifted by roots from the tree and sewer pipes into the property have been blocked/cleared on a number of occasions.
Council’s plumber advises that because the sewer line has had to be laid in an excavated sandstone channel it would be very expensive and impractical to re-locate the boundary trap and sewer pipes.
Council’s Tree Gang arborist has inspected the roots of the subject tree and is of the opinion that to sever all roots that are encasing the damaged sewer pipes would render the tree unstable and would also have a detrimental impact on its long-term health.
The installation of a tree root barrier is also not a feasible option because it would compromise the stability of the tree and roots would eventually just grow over or under any such barrier.
The only effective long-term solution to dealing with the problems currently being caused by the roots of this tree would be to remove it completely and replace it with a more appropriate tree species.
This is the only option that will allow the problems associated with the sewer system into the property to be repaired – even in the shorter term.
That approval be granted to remove the Council-owned Ficus ‘Hillii’ (Hill’s Weeping fig) growing on the nature strip outside 70 Ritchard Avenue, Coogee, and that it be replaced with a more appropriate tree species, as nominated in Council’s Street Tree Masterplan.
Several photographs detailing the extent and nature of root damage to
the sewer system of the property at
Gas pipe encased by fig tree roots
Size and significance of tree in streetscape
Roots encasing boundary trap and exposed bedrock
Boundary trap in relation to tree roots – completely surrounded
Tree in relation to powerlines, nature strip, footpath, other street trees
Proximity of excavation to tree trunk – approximately two metres