Works Committee Meeting

 

  BUSINESS PAPER

 

 

 

 

 

 

 

 

 

 

 

Tuesday 8 July 2008

 

 

 

 

 

 

 

 

 

Administrative Centre 30 Frances Street Randwick 2031

Telephone: 02 9399 0999 or

1300 722 542 (for Sydney metropolitan area)

Fax:02 9319 1510

general.manager@randwick.nsw.gov.au

www.randwick.nsw.gov.au


 

 

 

 

 

 

 

 

 

 

 

 


Works Committee

8 July 2008

 

 

 

1st July, 2008

 

 

Works Committee Meeting

 

 

Notice is hereby given that a Works Committee Meeting of the Council of the City of Randwick will be held in the Council Chamber, Town Hall, 90 Avoca Street, Randwick, on Tuesday, 8 July 2008 at 6:30pm.

 

 

Committee Members:           The Mayor, B Notley-Smith, Andrews, Belleli (Deputy Chairperson), Hughes (Chairperson), Matson, Seng, Tracey, White.

 

Quorum:                           Five (5) members.

 

NOTE:    At the Extraordinary Meeting held on 28 September 2004, the Council resolved that the Works Committee be constituted as a committee with full delegation to determine matters on the agenda.

 

Apologies/Granting of Leave of Absences 

Confirmation of the Minutes  

Works Committee Meeting - 10 June 2008

Declarations of Pecuniary and Non-Pecuniary Interests

Address of Committee by Members of the Public

Urgent Business

 

Works Reports

W16/08     Council-Owned Ficus 'Hillii' (Hill's Weeping Fig) Outside 70 Ritchard Avenue, Coogee    

 

Notice of Rescission Motions

Nil 

 

Closed Session

Nil

 

…………………………………………………….

Ray Brownlee

General Manager


Works Committee

8 July 2008

 

 

 

Works Report No. W16/08

 

 

Subject:                  Council-Owned Ficus 'Hillii' (Hill's Weeping Fig) Outside 70 Ritchard Avenue, Coogee

Folder No:                   F2004/07359

Author:                   Mark Shaw, Manager Technical Services     

 

Introduction

 

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.

 

Issues

 

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 Ritchard Avenue over the past decade or so as a result of fungal disease and/or root damage to private property and public infrastructure.

 

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.

 

Conclusion

 

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.

 

Recommendation

 

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.

 

Attachment/s:

 

1.View

Several photographs detailing the extent and nature of root damage to the sewer system of the property at 70 Ritchard Avenue, Coogee, and the significance of the tree in the streetscape.

 

 

 

 

 


Several photographs detailing the extent and nature of root damage to the sewer system of the property at 70 Ritchard Avenue, Coogee, and the significance of the tree in the streetscape.

Attachment 1

 

 

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