ms maggie cheng 1 wakeford street - strathfield.nsw.gov.au · letter of opinion – 1 wakeford...

ABN 14631973638

Letter of Opinion – RE: Three (3) Cupressus macrocarpa (Monterey Cypress) located at 1 Wakeford Street, Strathfield.

Treeism Arboricultural Services Pty Ltd

Consulting Arboriculturist Freshwater NSW 2096 Mobile: 0403 935 419 Email: [email protected]

Ms Maggie Cheng 1 Wakeford Street STRATHFIELD NSW 2135 18 February 2020 Dear Maggie, Arboricultural Assessment – One (1) Melaleuca quinquenervia at 6 Ronald Avenue, Freshwater.

At your request I attended the above site to review the health and condition of three (3) Cupressus

macrocarpa (Monterey Cypress) located at the above location.

To assist with my assessment, I have referred to the following:

x AS4970-2009 Protection of trees on development sites, Standards Australia;

x Strathfield Consolidated Development Control Plan (DCP) 2005 Part O Tree Management.

My assessment found the following:

x The subject tree in the front yard (Tree 1) appeared stable at the time of assessment but has recently

lost two (2) adjacent trees of the same species (See Plate 1), leaving it highly susceptible to

windthrow from north prevailing winds in the future.

x Two (2) subject trees in the rear yard (Tree 2 & 3) were noted as unstable at the time of assessment.

Tree 3 is in partial failure, ground heaving was noted, Tree 2 has some minor ground heave and a

significant opening between codominant stems in the canopy. Both trees pose an imminent danger

to property in my opinion.

TREE ASSESSMENT

Three (3) Cupressus macrocarpa (Monterey Cypress) are the subject of this assessment. See attached marked

up aerial photograph (Appendix C) for approximate tree location.

Tree 1 – Monterey Cypress – front yard

x This mature tree is located on the front western boundary of the site, on the boundary with number

1 Wakeford Street.

Letter of Opinion – 1 Wakeford Street, Strathfield. 18 February 2020 2 of 11

x It is approximately 14m tall with an average crown spread of 6m. The stem diameter at breast height

(DBH - measured at 1.4m above ground level) was calculated as 575mm.The tree is in good vigour

but fair to poor condition, it is trifurcate at 3m above ground level. The canopy has ‘separated’ slightly

and is sparse to the north (see Plate 2) given is has been suppressed by adjacent trees until recently.

x The tree has an estimated Useful Life Expectancy (ULE) of 4B (ULE categories see Appendix B Part 1).

x The tree has a low significance within the landscape (see Appendix B Part 2).

x The tree has been ascribed a Low Retention Value (RV – see Appendix B Part 3).

x The tree has been recently exposed to the north as two close proximity Monterey Cypress fell within

the last fortnight in a recent storm event. It is my opinion and experience that this species generally

does not develop an adequate root system to support its dense and tall canopy. Given the recent

exposure, this tree is susceptible to windthrow in the future.

x Gas lines are situated below the root crown of this tree, service lines to number 1 and 3 Wakeford

Street run either side (to the east and west) of the canopy. Low voltage power lines are located within

the target zone to the south. Permanent dwellings are located to the north of this tree within the

target zone.

Tree 2 – Monterey Cypress – rear yard

x This mature tree is located in a narrow garden bed, on the rear eastern boundary of the site, adjacent

to the existing driveway (see Plate 3).


was calculated as 475mm.

x The tree is in good vigour but poor condition, it has codominant stems at 1.6m above ground level

which then separates into multiple upright stems directly above this union. The codominant union

appears to have recently separated (see Plate 4). This poses a significant risk of large branch/stem

failure in the near future in my opinion.

x Minor ground heave was noted directly to the south-east of the stem. Ground probing with a 200mm

screwdriver found areas of air pockets directly adjacent to the tree to the south of the stem.

x It is possible root severance occurred during driveway construction given the close proximity of this

driveway to the tree stem.

x The tree has an estimated Useful Life Expectancy (ULE) of 4B.

x The tree has a low significance within the landscape.

x The tree has been ascribed a Low Retention Value (RV).

x The subject site dwelling is located within the target zone of this tree to the west.


Tree 3 – Monterey Cypress – rear yard

x This mature tree is located in the same narrow garden bed on the rear eastern boundary of the site,

as Tree 2.


was calculated as 575mm.

x The tree is in good vigour but poor condition, it has multiple stems at 3.5m above ground level. The

tree has a slight lean to the north.

x A low paver edge has been placed adjacent to the driveway but just clear of the base of stem. There

is evidence of recent cracking and movement of these pavers at the base of the tree (see Plate 5).

The soil/ground directly to the back (east) of the tree stem appears to have sunk, indication of this

can noted as discolouration on the existing timber fence. Ground heave was noted directly to the

south-east of the stem (see Plate 6). Ground probing with a 200mm screwdriver found large areas of

air pockets directly adjacent to the tree.

x It is my opinion this tree is actively failing.

x It is possible root severance occurred during driveway construction given the close proximity of this

driveway to the tree stem.

x The tree has an estimated Useful Life Expectancy (ULE) of 4B.

x The tree has a low significance within the landscape.

x The tree has been ascribed a Low Retention Value (RV).

x The subject site dwelling is located within the target zone of this tree to the west.

RECOMMENDATION

All three (3) Monterey Cypress have been ascribed a Low RV.

The subject trees in the rear yard (Tree 2 and 3) are, in my opinion, imminently dangerous.

The tree located in the front yard has been recently exposed and is susceptible to windthrow in the future in

my opinion given the large sail area and exposed canopy.

The three (3) subject trees should be removed. These trees will not recover to become safe amenity trees.

Removals are subject to authority approval.

Any removal work is carried out in accordance with the Safe Work Guide to Managing Risks of Tree Trimming

and Removal Work 2016, Work Health and Safety Act 2011, Work Health and Safety (WHS) Regulations 2011

and the Code of Practice for the Amenity Tree Industry 1998.


Please contact the undersigned via email [email protected] or phone 0403 935 419 to discuss

further if required.

Yours sincerely

BIBLIOGRAPHY Mattheck, C. & Breloer, H.(1999) The Body Language of Trees. Research for Amenity Trees No.4, The Stationary Office, London.

Chantalle Brackenridge Hughes Consulting arboriculturist and horticulturist. Tree Surgery Certificate Advanced Certificate Urban Horticulture Diploma of Horticulture (Arboriculture) Credit ISA Tree Risk Assessment Qualification (TRAQ) 2016 Accredited Member of the Institute of Australian Consulting Arborists (IACA) Member of the International Society of Arboriculture (ISA) Affiliate Member of the Local Government Tree Resources of Australia (LGTRA)


APPENDIX A - Photographs

Plate 1 – Tree 1 - Arrow notes subject tree, oval notes area between the subject tree and the site dwelling of stump grinding from recent tree removals following whole tree failures. Trees brought down service lines and lifted gas pipes.

Plate 2 – Arrow notes recently exposed canopy.


Plate 3 – Tree 2 & 3 – Arrows note gap left in garden paver edging given how close driveway is located to tree stems. Highly likely roots may have been severed during construction.

Plate 4 – Tree 2 - Arrows 200mm screwdriver placed between failing codominant stems.

T2

T3


Plate 5 (above) – Tree 3 - Arrow notes garden edging paver that has been pushed out/cracked with recent tree movement/active failure.

Plate 6 – Tree 3 – Red arrow notes changed soil level evident from moisture level marking on fence, grey arrow notes screwdriver in an air pocket.


Part 1 of 3—Useful Life Expectancy (ULE) ULE categories (after Barrell 1996, Updated 01/04/01) The five categories and their sub-groups are as follows:

1. Long ULE - tree appeared retainable at the time of assessment for over 40 years with an acceptable degree of risk, assuming reasonable maintenance:

a) Structurally sound trees located in positions that can accommodate future growth b) Trees which could be made suitable for long term retention by remedial care c) Trees of special significance which would warrant extraordinary efforts to secure their long term

retention

2. Medium ULE - tree appeared to be retainable at the time of assessment for 15 to 40 years with an acceptable degree of risk, assuming reasonable maintenance: a) Trees which may only live from 15 to 40 years b) Trees which may live for more than 40 years but would be removed for safety or nuisance

reasons c) Trees which may live for more than 15 years but would be removed to prevent interference with

more suitable individuals or to provide space for new planting d) Trees which could be made suitable for retention in the medium term by remedial care

3. Short ULE - tree appeared to be retainable at the time of assessment for 5 to 15 years with an acceptable degree of risk, assuming reasonable maintenance:

a) Trees which may only live from 5 to 15 years b) Trees which may live for more than 15 years but would be removed for safety or nuisance

reasons c) Trees which may live for more than 15 years but would be removed to prevent interference with

more suitable individuals or to provide space for new planting d) Trees which require substantial remediation and are only suitable for retention in the short term.

4. Removal - trees which should be removed within the next 5 years:

a) Dead, dying, suppressed or declining trees b) dangerous trees through instability or recent loss of adjacent trees c) Dangerous trees because of structural defects including cavities, decay, included bark, wounds

or poor form d) Damaged trees that are clearly not safe to retain e) Trees which may live for more than 5 years but would be removed to prevent interference with

more suitable individuals or to provide space for new planting f) Trees which are damaging or may cause damage to existing structures within the next 5 years g) Trees that will become dangerous after removal of other trees for the reasons given in (a) to (f) h) Trees in categories (a) to (g) that have a high wildlife habitat value and, with appropriate

treatment, could be retained subject to regular review

5. Small, young or regularly pruned - Trees that can be reliably moved or replaced: a) small trees less than 5m in height b) young trees less than 15 years old but over 5m in height

formal hedges and trees intended for regular pruning to artificially control growth.

APPENDIX B - Tree Retention Value


The landscape significance of a tree is an essential criterion to establish the importance that a tree may have on a site. All definitions for terms used in the Tree Significance - Assessment Criteria and Tree Retention Value - Priority Matrix, are taken from the IACA Dictionary for Managing Trees in Urban Environments 2009. The system uses a scale of High, Medium and Low significance in the landscape. Once the landscape significance of an individual tree has been defined, the retention value can be determined. Tree Significance - Assessment Criteria

1. HIGH SIGNIFICANCE IN LANDSCAPE

The tree is in good condition and good vigour The tree has a form typical for the species The tree is a remnant or is a planted locally indigenous specimen and/or is rare or uncommon in the local area or of botanical interest or of substantial age The tree is listed as a Heritage Item, Threatened Species or part of an Endangered Ecological Community, or listed on Councils Significant Tree Register The tree is visually prominent and visible from a considerable distance when viewed from most directions within the landscape due to its size and scale and makes a positive contribution to the local amenity The tree supports social and cultural sentiments or spiritual associations, reflected by the broader population or community group or has commemorative values The tree’s growth is unrestricted by above and below ground influences, supporting its ability to reach dimensions typical for the taxa in situ - tree is appropriate to the site conditions

2. MEDIUM SIGNIFICANCE IN LANDSCAPE

The tree is in fair-good condition and good or low vigour The tree has a form typical or atypical for the species The tree is a planted locally indigenous or a common species with its taxa commonly planted in the area The tree is visible from surrounding properties, although not visually prominent as partially obstructed by other vegetation or buildings when viewed from the street. The tree provides a fair contribution to the visual character and amenity of the local area. The tree’s growth is moderately restricted by above and/or below ground influences, reducing its ability to reach dimensions typical for the taxa in situ.

3. LOW SIGNIFICANCE IN LANDSCAPE

The tree is in fair-poor condition and good or low vigour The tree has a form atypical for the species The tree is not visible or is partly visible from surrounding properties as obstructed by other vegetation or buildings The tree provides a minor contribution or has a negative impact on the visual character and amenity of the local area. The tree is a young specimen which may or may not have reached dimension to be protected by local Tree Preservation orders or similar protection mechanisms and can easily be replaced with a suitable specimen The tree’s growth is severely restricted by above or below ground influences, unlikely to reach dimensions typical for the taxa in situ - tree is inappropriate to the site conditions The tree is listed as exempt under the provisions of the local Council Tree Preservation Order or similar protection mechanisms The tree has a wound or defect that has potential to become structurally unsound. Environmental Pest / Noxious Weed Species –The tree is an Environmental Pest Species due to its invasiveness or poisonous/ allergenic properties –The tree is a declared noxious weed by legislation Hazardous/Irreversible Decline –The tree is structurally unsound and/or unstable and is considered potentially dangerous –The tree is dead, or is in irreversible decline, or has the potential to fail or collapse in full or part in the immediate to short term

The tree is to have a minimum of three (3) criteria in a category to be classified in that group. The assessment criteria are for individual trees only, however, can be applied to a monocultural stand in its entirety e.g. hedge.

In the development of this document IACA acknowledges the contribution and original concept of the Tree Significance & Retention Value Matrix, developed by Footprint Green Pty Ltd and Andrew Morton in June 2001. NOTE: The landscape significance criteria of the subject tree as determined and highlighted above.

Part 2 of 3—IACA Significance of a Tree, Assessment Rating System (STARS)©


Part 3 of 3—Tree Retention Value Priority Matrix

Significance 1. High 2. Medium 3. Low Significance in

Landscape Significance in Landscape

Significance in Landscape

Environmental Pest / Noxious Weed Species

Hazardous / Irreversible Decline

Estim

ated

Life

Exp

ecta

ncy

1. Long >40 years

2. Medium 15-40 Years

3. Short <1-15 Years

4. Removal >5 Years

Legend for Matrix Assessment Priority for Retention (High) -These trees are considered important for retention and should be retained

and protected. Design modification or re-location of building/s should be considered to accommodate the setbacks as prescribed by the Australian Standard AS4970 Protection of trees on development sites. Tree sensitive construction measures must be implemented e.g. pier and beam etc if works are to proceed within the Tree Protection Zone.

Consider for Retention (Medium) -These trees may be retained and protected. These are considered less critical; however, their retention should remain priority with removal considered only if adversely affecting the proposed building/works and all other alternatives have been considered and exhausted.

Consider for Removal (Low) -These trees are not considered important for retention, nor require special works or design modification to be implemented for their retention.

Priority for Removal -These trees are considered hazardous, or in irreversible decline, or weeds and should be removed irrespective of development.

IACA, 2010, IACA Significance of a Tree, Assessment Rating System (STARS), Institute of Australian Consulting Arboriculturists, Australia, www.iaca.org.au REFERENCES Australia ICOMOS Inc. 1999, The Burra Charter – The Australian ICOMOS Charter for Places of Cultural Significance, International Council of Monuments and Sites, www.icomos.org/australia Draper BD and Richards PA 2009, Dictionary for Managing Trees in Urban Environments, Institute of Australian Consulting Arboriculturists (IACA), CSIRO Publishing, Collingwood, Victoria, Australia. Footprint Green Pty Ltd 2001, Footprint Green Tree Significance & Retention Value Matrix, Avalon, NSW Australia, www.footprintgreen.com.au


Figure 1 – N

SW Six M

aps Aerial Photography. Not to scale. M

arked up by C. Hughes.

APPENDIX C - Tree Location Plan

ms maggie cheng 1 wakeford street - strathfield.nsw.gov.au · letter of opinion – 1 wakeford...

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