attachments under separate cover monday 10 …...remove existing window. keep for possible reuse....

Town of Gawler Council Assessment Panel

ATTACHMENTS UNDER SEPARATE COVER

Monday 10 September 2018 Item Page No

5.3 Development Application: 490/605/2017 49 Applicant: JOHN SCHEEPENS DESIGN &

CONSTRUCTION Address: 36 Main North Road, Willaston

Nature of Development: Change of land use from residential to consulting room and partial demolition alterations and additions to existing building including associated landscaping and car parking

Attachment 1 - Attachment 2 - Attachment 3 - Attachment 4 - Attachment 5 - Attachment 6 - Attachment 7 -

Application Plans and Documentation External Referral documentation Internal Referral documentation Arborist’s Report Additional Information – Applicant Traffic Consultant’s Report Previous Report

51 91 98 102 137 143 148

Page 49 of 210

of 210

CEDAR

43.24

3.24

40.00

SCALE:1:100

D GILFILLAN

36 MAIN NORTH ROAD, WILLASTON SA

S2517

ADDITION/RENOVATIONS TO EXISTING BUILDING - CHANGE OF USE TO CONSULTING

17/11/2017

1:

of 04Existing: 90.11

New Works: 17.12

Front Verandah: 16.75

Rear Verandah: 11.87

135.85

SOUTH-EAST ELEVATION

04

100 u.o.n

ELEVATIONS

m²

SOUTH-WEST ELEVATION

A3 Sheet

NORTH-WEST ELEVATION

NORTH-EAST ELEVATION

External wall cladding as selected.

Timber framed double hungwindows as selected.

External wall claddingas selected.

Existing roof to remain.

New 900mm wide entry dooras selected.

Build new wall to toilet& entry as required.


Existing roof to remain.Create parapet wall to entry.Line with Scyon Matrix.

ATTACHMENT 1

Page 51 of 210

CEDAR

43.24

3.24

40.00

SCALE:1:100

D GILFILLAN


S2517


17/11/2017

1:


New Works: 17.12



135.85

02

EXISTING/DEMOLITION LAYOUT & ELEVATIONS

m²

100 u.o.n

A3 Sheet

Remove existing bathroom/rear wall,windows & slab as required.Extent shown dashed.

VERANDAHVERANDAH

BEDROOM

BEDROOMLIVING

BEDROOM

KITCHEN

BATHROOM

SOUTH-WEST ELEVATION

NORTH-WEST ELEVATION

NORTH-EAST ELEVATION

Existing roof to remain.Prop roof as required.

Extent of roof over to remain

Remove existing internal door& jambs as required for accessibleaccess. Make good opening.

Remove existing window.Keep for possible reuse.

Remove existing door & window.Prepare opening for new window.

Remove existing kitchen cupboards.

Remove existing door & window.Prepare opening for new window.

Remove existing bathroom/rear wall,windows & slab as required.Extent shown dashed.

Existing roof to remain.Prop roof as required.

Remove existing window.Keep for possible reuse.

Create opening in existing wall.Provide lintel over as required.Prepare for new door.Make good opening.

Page 52 of 210

CEDAR

43.24

3.24

40.00

SCALE:1:100

D GILFILLAN


S2517


17/11/2017

1:


New Works: 17.12



135.85

03

100 u.o.n

PROPOSED FLOOR LAYOUT

m² A3 Sheet

209090

2180

CONSULTATION 2

CONSULTATION 1RECEPTION

CONSULTATION 3

KITCHEN

ENTRY

ACCESSIBLEWC

Broom/pantry

Fridge

hot plate

Sinkd/w

wm

Pan

900

900

m/w over

Basin

9027

0090

2640

3940

External wall cladding as selected.

Timber framed double hungwindows as selected.

New 900mm wide entry dooras selected.

Create parapet wall to entry.Line with Scyon Matrix.


Existing roof to remain.

Install new kitchen.Kitchen cupboard layout toowner's selection & to joiner'sspecification

Provide new floor to kitchen, entry & accessible wc.Finished floor level to match main building floorlevel. (New slab to WC, self levelling topping tokitchen/entry)

VERANDAH

VERANDAH

90

900

Provide new door tonew opening.

hws

380090

1710

Basin

vanity

Provide new basin toconsultation 3.

Exit

Exit

fe fe

fefb

Exit

fe

FHR

fb

Combined emergency lighting and exit lightconnected to mains power, with additional 9 volt batterypowered back up, fixed to ceiling.All doors in path of egress must be operable without a key.Combined emergency and exit light complying with AS2293.1

Emergency pin light with 9 volt battery back up..

2.4Kg 'all round' dry chemical portable fire extinguisher(Note: This extinguisher may cause damage to computeror similar electronic equipment) ..........or3.4Kg Co² portable fire extinguisher.

Fire Blanket

Fire Hose reel

Fire hazard properties: General requirements.Any material or component used in this building must -a) in the case of sarking type material, have a flammabilityindex not more than 5; orb) in the case of other materials have -(i) a spread-of-flame index not more than 9; and(ii) a smoke-developed index not more than 8 if thespread-of-flame index is more than 5 orc) be completely covered on all faces by concrete or masonrynot less than 50mm thick; ord) in the case of a composite member or assembly, be constructedso that when assembled as proposed in a building-(i) any material which does not comply with a) or b) is protectedon all sides and edges from exposure to the air; and(ii) the member or assembly, when tested in accordance with thespecification A2.4, has a smoke-developed index and spread-of-flameindex not exceeding those prescribed in b) above; and(iii) the member or assembly retains the protection in position sothat it prevents ignition of the material and continues to screenit from access to free air for a period of not less than 10 minutes.

Page 53 of 210

CEDAR

43.24

3.24

40.00

SCALE:1:100

D GILFILLAN


S2517


27/03/2018

1:


New Works: 17.12



135.85

A: Site plan amendments in response to council queries

B: Site plan amended for arborist's reccommendations

C: Site plan amended. Drive & carpark design levels added

D: Permeable paving changed to Ecotrihex

01

200 u.o.n

SITE PLAN

m²

M A I N N O R T H R O A D

ExistingBuilding

Drive

Proposed entry& rebuilt bathroom.Extent shown hatched

SITE PLANDischarge Stormwater into Existing rainwater tanksthrough 90mm diamater stormwater class upvc pipes.Discharge overflow to street water table.

74.22m

CT 6099/83Lot 103 Deposited Plan 89090In the Area Named WILLASTONHundred of MUDLA WIRRA

D

A3 Sheet

18.1

9m

Existing trees to remain13.55m

61.12m

Create accessible carpark& associated shared spaceas per AS2890.6

14.80m12.06m

6000

4800

6810

4800

2400

New rainwater tank with pump to catch roof stormwater.Connect to toilet cistern, to office. Discharge overflow intostormwater system.

Existing sewer run, connected to town effluent.

Landscaping Specie Selection

Rhagodia parabolica 1-2m Saltbush

Acacia notabilis 3-6m Wattle

Acacia sclerophylla 1-2m Wattle

Rytidosperma species 0.6m Wallaby Grass

Existing crossover to remain.

Foot

path

Footpath

Vera

ndah

Footpath

Carpark(permeable surface)

5400

1000

Proposed landscaping usingnative/indiginous species.

T1Riv

er red

gum

cir = 4

.47m

T2

Sugar

gum

cir = 3

.06m

Bicycle parking

+ 98.1

6 TOK

+ 98.3

3

+ 98.5

2

+ 98.1

85

+ 98.3

35

+ 98.8

6

+ 99.6

8

+ 99.6

8

+ 98.9

6

+ 98.4

9

+ 99.5

4

+ 99.9

9 PL

+ 100

.00 FL

+ 99.2

4

+ 99.7

95

+ 99.7

25

2700

Grade carpark& drive at 1:20

Proposed swale to catchcatch stormwater run off.

Proposed swale to catchcatch stormwater run off.

Car Parking Surface Selection

Concrete 150mm thick Max.

Ecotrihex permeable

Cut

Existing tree to be removed.(shown dashed)

Wheelie Bin storage

+ 98.0

2 BOK

+ 98.3

95 TO

K

+ 98.2

5 BOK

+ 98.3

5

+ 98.4

75

+ 98.6

6

+ 98.4

7

+ 98.5

0

+ 98.7

6

+ 98.5

45

Existing tree to be removed.(shown dashed)

T1Structural Root Zone- 3.9m radius

T1Tree Protection Zone- 15.0m radius

T2Structural Root Zone- 3.4m radius

T2Tree Protection Zone- 11.6m radius

DL 98.75

DL 98.50

Page 54 of 210

TREE REPORT 36 Main North Road Willaston

Prepared for: Denise and Katie Gilfillan 21 Elizabeth St Croydon SA 5008 27 March 2018 Prepared by: Michael Palamountain Consulting Arborist Tree Environs Pty Ltd

Page 55 of 210

Tree Assessment at 36 Main North Rd, Willaston ________________________________________________________

2 | P a g e Managing trees in the urban landscape

Table of Contents SUMMARY ....................................................................................................................................................... 3

INTRODUCTION ................................................................................................................................................ 4

BRIEF .................................................................................................................................................................... 4 QUALIFICATIONS ..................................................................................................................................................... 4 DOCUMENTS AND INFORMATION PROVIDED ................................................................................................................. 4 RELEVANT BACKGROUND INFORMATION....................................................................................................................... 4

OBSERVATIONS ................................................................................................................................................ 5

SITE VISIT ............................................................................................................................................................... 5 SITE DESCRIPTION .................................................................................................................................................... 5 TREE 1 .................................................................................................................................................................. 6 TREE DIMENSIONS ................................................................................................................................................... 7 TREE HEALTH .......................................................................................................................................................... 8 TREE STRUCTURE ..................................................................................................................................................... 8 TREE 2 .................................................................................................................................................................. 9 TREE DIMENSIONS ................................................................................................................................................. 10 TREE HEALTH ........................................................................................................................................................ 11 TREE STRUCTURE ................................................................................................................................................... 12 PROPOSED DEVELOPMENT ACTIVITIES ........................................................................................................................ 13

APPRAISAL ..................................................................................................................................................... 14

TREE HEALTH ........................................................................................................................................................ 14 TREE STRUCTURE ................................................................................................................................................... 14 TREE PROTECTION ZONE ......................................................................................................................................... 15

TREE PROTECTION.......................................................................................................................................... 16

PROTECTIVE FENCING ............................................................................................................................................. 16 SITE PREPARATION/EARTHWORKS ............................................................................................................................. 17 UNDERGROUND SERVICES ....................................................................................................................................... 17 PAVING ............................................................................................................................................................... 18 LANDSCAPING ....................................................................................................................................................... 18 FENCING .............................................................................................................................................................. 18 FINES .................................................................................................................................................................. 18

CONCLUSION ................................................................................................................................................. 20

RECOMMENDATIONS ..................................................................................................................................... 21

PRUNING ....................................................................................................................................................... 23

PAVING WORKS ............................................................................................................................................. 24

PAVEMENT INSTALLATION PRACTICES ......................................................................................................................... 26 Example - Permeable paving on aggregate base ........................................................................................ 28

LANDSCAPING AROUND ESTABLISHED TREES ................................................................................................ 29

ENDNOTES ..................................................................................................................................................... 32

Appendices: Tree Protection Zones Plan

Page 56 of 210



Summary

• Tree Environs assessed two significant trees at 36 Main North Rd, Willaston in relation to an upgrade and change of use proposal for the site.

• Both trees are proposed to be retained, and require some pruning to improve tree form and maintain acceptable levels of risk at the site.

• A new driveway crossover and permeable paved car parking area are proposed, within the tree protection zones of both trees.

• The design solution for these surfaces has considered the needs of the trees, by minimising earthworks, using shallower profiles for the crossover and using permeable paving for the car parking area.

• Additional landscaping around the trees will assist in improving growing conditions for the trees.

• These works are not likely to adversely affect the trees if installed correctly with care. • A range of tree protection measures are outlined to ensure the impact on the trees is minimal.

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Introduction Brief I carried out an assessment of two significant trees at 36 Main North Road, Willaston on the 13th February following a request from the property owners, Denise and Katie Gilfillan. I was requested to assess the legal status of the trees, tree condition, tree retention suitability and tree management requirements. I am also to assess the possible impacts of the proposed development activities at the site on the trees and to recommend strategies to minimise these possible impacts. Qualifications I have based this report on my education, experience, ongoing training, site observations and the information provided to me. I have nineteen years’ experience in the field of arboriculture, both as a practicing (climbing) and consulting arborist. I have climbed and pruned in excess of 1,000 mature trees and assessed in excess of 10,000 trees. A summary of my qualifications includes:

• Bachelor of Science (Botany and Ecology) – University of Sydney (1994) • Diploma of Horticulture (Arboriculture) (2005) • Certified Arborist (#AU – 0007A) – International Society of Arboriculture (2003). I have

maintained Continuing Professional Development with this certification. • I am a registered consulting arborist with Arboriculture Australia. I have maintained

Continuing Professional Development with this certification. • Tree Risk Assessment Qualification (TRAQ) - International Society of Arboriculture (2013) • Quantified Tree Risk Assessment (QTRA) – (2006) (#770)

Documents and information provided I was provided with the following documents to assist me in the preparation of this report;

• A Site Plan dated 16th March 2018 – Revision C prepared by John Scheepens Design and Construction.

Relevant background information The existing building on the site has previously been used as a residential tenancy. It is now proposed to alter the use of the property to consist of consulting rooms with associated access and car parking at the front of the property. The property owners have expressed a desire to retain two trees located at the front of the property. After some initial site meetings, a range of challenges were identified in installing a new driveway and crossover between the two trees at the front of the property. With a series of discussions and design reviews, the current proposal aims to retain the two trees, minimise any adverse impacts on the trees and meet the required car parking and access requirements.

Page 58 of 210



Observations Site visit I had full access to the trees in question and observations were from what was visible from within and around the property boundaries. I carried out a level 2 assessment of the treesa and all my observations were visual from ground levelb. All dimensions marked (~) are estimates. Site description The site consists of a single dwelling on a large allotment with several trees of low density scattered across the property. It is adjacent to several commercial businesses with a similarly arranged car parking area to the front of the property. The dwelling is listed as a Contributory Item in Table Ga/6 of the Town of Gawler Development Plan. The two trees forming the subject of this report are located at the front of the property, as indicated in the image below.

Tree 1

Tree 2

Page 59 of 210



Tree 1 The first tree in question is a Eucalyptus camaldulensis or River red gum which is the most widespread species of eucalypt in Australia, occurring in every mainland State. It is notably a tree of riverine sites whether of permanent or seasonal water, often extending to adjoining floodplains and into the slopes. It is a medium sized woodland tree (up to 45m) with a short, thick bole, smooth bark in irregular plates of varying colour, rough bark at the base and large open crown. It is distinguished by the opercula which are normally strongly beaked. This species dominates the Murray-Darling river systems. It also occurs on lower Eyre Peninsula, Kangaroo Island, Yorke Peninsula, the south-east of South Australia and the adjacent Glenelg River system as well as the intervening plains of western Victoria and streams as far east as Sale in eastern Victoria. It also naturally occurs in the hills of the Mt Lofty Ranges and plains around Adelaide and the south east of South Australia. Annual rainfall for the Murray Darling form is between 325-750mmc. It is indigenous to many parts of Adelaide and Gawler and notably provides a wide range of environmental and amenity benefits to the areas in which it occurs. The tree has a good tolerance to development activities and copes well with challenging growing conditions. It is located on the front boundary of the property as follows (measured from centre of trunk):

• 6.4m from the side boundary to the north east. • 1.7m from the front boundary to the south east

Within the site to the north and west, the growing environment is open, undisturbed with natural leaf litter. The site gradually slopes upwards towards the north. Outside the site to the SE are a pedestrian footpath (recently modified to consist of a rubber soft fall surface), an existing concrete driveway crossover (recently upgraded) and the bitumen roadway. I also understand recent hydro-excavation works occurred along the road edge to upgrade underground services, whilst retaining tree roots.

Tree 1 Tree 2

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Tree dimensions

Height 22m Crown spread ~24m Trunk circumference 1m above ground level

4.47m

Diameter at breast height (DBH) d 1440mm Diameter above root flare 1.49m Approximate age of tree 100-150 years The TPZ radiuse from the centre of the trunk.

15m

The TPZ areaf around tree 707m² The Structural Root Zoneg (SRZ) radius from the centre of the trunk

3.9

This tree qualifies as a significant tree under the Development Act 1993.

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Tree health This tree is in average health. Foliage colour, distribution and density are average for this species. There are a moderate number of dead branches in the crown, some of which are up to ~200mm in diameter. There is evidence of minor borer activityh on the lower trunk which is typical and normal for a tree of this species and age. While this species is generally well suited to the local area, it is out of its ideal setting at this slightly elevated site (in comparison to its preferred low land areas). In addition, decades of roadworks, footpath works, installation and repair of underground services and harsh pruning practices have had some impact on tree health. However, this is a robust, tolerant and long lived species and can endure such activities better than most other tree species. I do not consider it to have a short life expectancy. Tree structure This tree’s structure consists of a single trunk with three primary stems and secondary branchesi from ~4m to form a moderately broad spreading crown with a moderate density of branches with an overall ascending habit. There are several smaller diameter, lower drooping branches that may interfere with future vehicle movements on site. These can easily be addressed with minor pruning that will have little impact on the tree. The tree has been loppedj (harshly pruned) in previous decades on at least two occasions, at approximately 4m-6m above the ground. The resulting epicormic shootsk form the current crown of the tree. These stems are well attached to the lopping points and are free of bark inclusions or other notable defects. There are several small hollows around these historical lopping points (providing some habitat value). There is good wood growth around these hollows and no evidence of notable internal decay or instability. I found no evidence of recent notable branch failure from the crown of this tree. Apart from the two (or more) lopping episodes in previous decades, the tree has had some minor pruning to clear power lines and the roadway to the SE and low branches removed for clearances within the site. I found no evidence of recent pruning to manage the remainder of the crown of this tree. Pruning works to remove larger dead branches, and minor crown lifting pruning (for vehicle clearances) will assist in improving tree aesthetics and maintaining acceptable levels of risk at the site.

Page 62 of 210



Tree 2 The second tree in question is a Eucalyptus cladocalyx or Sugar gum which is a medium to tall woodland or forest tree (up to 35m) with a smooth mottled trunk, discolourous glossy leaves and white flowers in multiples of 7-11 developing on leafless sections of the branchlets. It is endemic to South Australia and restricted to four disjunct locations in the southern Flinders Ranges, Kangaroo Island and two locations on the Eyre Peninsula. It lacks a lignotuber but possesses epicormic buds along the main stems, ready to develop new shoots in response to a stress event. It is not indigenous to the Adelaide area, but is tolerant of drought and urban pollution. It is widely planted in Adelaide and well suited to the climatic conditionsl. It is located on the front boundary of the property as follows (measured from centre of trunk):

• 10.4m from the side boundary to the north east. • 1.2m from the front boundary to the south east

Within the site to the north and west, the growing environment is open, undisturbed with natural leaf litter. The site gradually slopes upwards towards the north. Outside the site to the SE are a pedestrian footpath (recently modified to consist of a rubber soft fall surface), an existing concrete driveway crossover (recently upgraded) and the bitumen roadway. I also understand recent hydro-excavation works occurred along the road edge to upgrade underground services, whilst retaining tree roots.

Page 63 of 210



Tree dimensions

Height 18m Crown spread ~20m Trunk circumference 1m above ground level

3.06m

Diameter at breast height (DBH) 970mm Diameter above root flare 1.07m Approximate age of tree 80-100 years The TPZ radius from the centre of the trunk.

11.6m

The TPZ area around tree 426m² The Structural Root Zone (SRZ) radius from the centre of the trunk

3.4

This tree qualifies as a significant tree under the Development Act 1993.

Page 64 of 210



Tree health This tree is in average health. Foliage colour, distribution and density are good. However, there are large sections of dieback where two upper stems to the east have previously died back by more than 50%. One of these has been cut back in the past, whilst the other remains emerging through the upper crown (see image below). This dieback may be related to previous decades of roadworks, footpath works, installation and repair of underground services and harsh pruning practices. Current foliage appearance indicates the tree has largely recovered from such previous activities and is growing well. I do not consider it to have a short life expectancy. There are a moderate number of dead branches in the crown, some of which are up to ~300mm in diameter. There is evidence of minor borer activity on the lower trunk which is typical and normal for a tree of this species and age. While this species is generally well suited to the local area, it is out of its ideal setting at this slightly elevated site (in comparison to its preferred low land areas). In addition, decades of roadworks, footpath works, installation and repair of underground services and harsh pruning practices have had some impact on tree health. However, this is a tolerant and long lived species and can endure such activities better than most other tree species. I do not consider it to have a short life expectancy.

Page 65 of 210



Tree structure This tree’s structure consists of a single trunk with five primary stems and secondary branches from ~4m to form a moderately broad spreading crown with a moderate density of branches with an overall ascending habit. This tree has also been lopped in previous decades on at least two occasions, at approximately 4m above the ground. The resulting epicormic shoots form the current crown of the tree. The primary stems are well attached to the lopping points and are free of bark inclusions or other notable defects. There are several moderate sized hollows around these historical lopping points (providing some habitat value). There is good wood growth around these hollows and no evidence of notable internal decay or instability. The two large dead stems noted previously remain in the tree. One has been cut back substantially. The other remains tall, upright and emerging through the upper crown. A live branch is attached to this dead stem at ~10m to the east, and overhangs the road. This branch is becoming over extended with an average attachment to the main (dying) stem. I found no evidence of recent notable branch failure from the crown of this tree. Apart from the lopping episodes in previous decades, the tree has had some minor pruning to clear power lines and the roadway to the SE and one of the dead stems cut back. I found no evidence of recent pruning to manage the remainder of the crown of this tree. Pruning works to remove larger dead branches, and reduce leverage of branches overhanging the road will assist in improving tree aesthetics and maintaining acceptable levels of risk at the site.

Page 66 of 210



Proposed development activities The proposed development activities at the site include:

• Refurbishment of the existing dwelling to convert it from residential use to commercial use. • Formalising site access with a new crossover between the subject trees at the front of the

property. The crossover is proposed to consist of reinforced concrete sections bridging over the structural root zones of the subject trees. This is in preference to a permeable paving crossover, which requires deeper excavations to achieve the required permeable profile and finished levels/grades.

• The remainder of the car parking area will be constructed using a permeable pavement within the tree protection zones of the two subject trees. No excavation is proposed to install the permeable paving in this area.

• Garden areas surrounding the trees will be improved with shallow swales to capture any runoff from the permeable paved surfaces and planted out with native/indigenous species.

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Appraisal The two subject trees qualify as significant trees and provide a wide range of benefits to the local community and environment. The proposed development has been designed in consultation with Tree Environs with the aim to preserve these benefits. Tree health Both trees are in average health, due to their history of pruning, maintenance of the nearby road and footpath, and installation and repair of underground services. They are both robust trees that have tolerated these activities to date. Neither tree is considered to have a short life expectancy. If the trees and their surrounding growing environment (soil) are protected from the potentially adverse impacts of the proposed development process and well maintained in the future, both trees can remain an asset at the site for many years. The paving and landscape design have carefully considered the needs of the tree and have utilised tree friendly strategies to minimise the impacts on the root system, while at the same time, improve their growing conditions. Tree structure Both trees have a limited history of pruning in recent years to manage their crowns. Some pruning is necessary to improve tree form, remove larger dead branches and to provide suitable clearances within the site. Tree 1 requires pruning works to remove larger dead branches, and minor crown lifting pruning within the site for vehicle clearances. Tree 2 requires pruning works to remove larger dead branches, and reduce leverage of branches overhanging the road. This pruning must not remove tree parts excessively and must not be performed by building contractors. All pruning must conform to the Australian Standard AS 4373 – 2007 Pruning of Amenity Trees. All pruning should be carried out or supervised by appropriately qualified and experienced arborists. Pruning specifications are outlined in the recommendations.

Page 68 of 210



Tree Protection Zone To protect these trees from the possible adverse impacts of development activities, a tree protection zone (TPZ) is required. TPZs preserve tree root systems and the immediate soil environs as well as protecting the above ground parts of the trees from inadvertent crown or trunk damage. The tree protection zone for these trees is calculated as follows; Tree 1 Tree 2 The TPZ radius from the centre of the trunk 15.0m 11.6m The TPZ area around tree 707m² 426m² The Structural Root Zone (SRZ) radius from the centre of the trunk

3.9m 3.4m

Trees can tolerate some encroachment into their TPZm. The proposed development activities at the site encroach into these TPZ areas as follows; Tree 1 – River red gum

• The proposed concrete portion of the driveway crossover encroaches into the TPZ by ~62m² (8.8%)

• The proposed permeable paving encroaches into the TPZ by ~154m² (21.8%) • The total level of encroachment from these activities is ~216m² (30.6%) • The concrete crossover is within the Structural Root Zone.

Tree 2 – Sugar gum

• The proposed concrete portion of the driveway crossover encroaches into the TPZ by ~62m² (14.6%)

• The proposed permeable paving encroaches into the TPZ by ~42m² (9.9%) • The total level of encroachment from these activities is ~104m² (24.5%) • The concrete crossover is within the Structural Root Zone.

The total level of encroachment for both trees is major encroachment (>10%). Consideration has been given to a range of factors as outlined in section 3.3.4 TPZ encroachment considerations as outlined in the Australian Standard AS 4970-2009 Protection of trees on development sites as follows:

• The concrete crossover passes over the structural root zone of both trees; o These areas are not proposed to be excavated by machinery. o Light hand excavation of soils will be necessary to achieve the lowest possible levels

for the crossover, without damaging tree roots. o Coarse granular fill material will be applied to fill in lower lying areas/depressions to

achieve a level base layer. o 150mm thick reinforced concrete will be installed on top of this levelled area to

support vehicle traffic. o This profile is shallower than would be required for a fully permeable surface and base

layers, resulting in no excavations and a lower finished paving level. o No notable root damage is likely to occur if the crossover is installed in this manner.

• Permeable pavement will be installed in the remainder of the car parking area within tree protection zones;

o These areas are not proposed to be excavated by machinery. o Light hand excavation of soils in some higher areas may be necessary to achieve

levels without damaging tree roots.

Page 69 of 210



o Permeable fill material will be applied to fill in lower lying areas/depressions to achieve a level base layer.

o Permeable Ecotrihex pavers will be installed on top of this levelled area for car parking.

o These layers are permeable and will allow sufficient air and moisture to reach the root zone of both trees.

o No root damage is likely to occur if installed in this manner. • The remaining areas will be landscaped in a manner that captures any water runoff (swales)

and will be planted out using low native/indigenous plants. After considering these factors, the proposed driveway and crossover design in its current form is considered acceptable.

Tree Protection To protect those trees to be retained on a development site, consideration must be given to the various activities that are occurring within the vicinity of these trees. Modifications to the pavement materials and installation methodology have been considered. In addition, protective fencing and other protective measures are required during the entire development process. In relation to the proposed development at this site, the following is required. Protective fencing Protective fencing should ideally be erected around the trees to be retained on site prior to any development activities commencing. This fencing is to protect the tree trunks and branches during paving and concreting works. This is not possible at this site, as the driveway is to be constructed between the existing trees. The following guidelines should be followed:

• Restrict vehicle access between the two trees whilst building refurbishment is occurring. Access to the building area should be from the adjoining land/car park area to the north.

• Restrict builders using the tree protection zone areas within the site for storage, material delivery, skip bins/waste disposal etc. This can be achieved with temporary fencing or bunting out to the extent of the tree protection zone within the subject site.

• This temporary fencing can then be removed to facilitate the installation of permeable paving and the concrete driveway crossover.

Page 70 of 210



Site preparation/earthworks The preparation of the car parking area and driveway crossover requires a range of activities such as levelling, grade changing and trenching for footings and underground services. These activities usually require heavy machinery to move about on the site and can potentially cause harm to the tree, surrounding soils and its root system. In relation to the installation of the crossover and permeable paved car park, the following is required:

• Remove temporary protective fencing to access the area for these works. • Limit site access within the tree protection zone/structural root zone for paving contractors and

landscaping contractors. Full site access between the trees can begin once paving works are completed.

• Works within the structural root zone/tree protection zone should be carried out after all relevant contractors have been briefed by the project arborist.

• To lower the soil levels and associated leaf litter layers between the trees within the structural root zone, works must be carried out by hand using light hand tools. The grade should be carefully lower until woody roots are encountered. This defines the lowest level the area can be reduced to. Consultation with the project arborist may be required during this stage.

• Outside the structural root zone (but within the tree protection zone) some lowering of soil levels and associated leaf litter layers can occur carefully by hand.

• The remainder of the low lying areas should be filled with a coarse aggregate that provides suitable load bearing capacity for the intended loads, whilst retaining high levels of permeability for the root system of the trees.

Underground services Several underground services are required to service the property. Most of these are currently in place and operational. I am unaware if any require upgrading at this point in time. If so, there is potential that they may be required to pass in close proximity to trees. Where new underground services are required, these should be routed outside of the TPZ areas. If underground services must pass through a TPZ, they must utilise underground boring methods, hydro excavation or manually excavated trenches where tree roots are left intact and undamaged.

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Paving Paving works often require excavation works, soil compaction and the installation of impervious surfaces. These can all have an adverse impact on the soil and the trees root system which can adversely affect tree health. The paving works at this site have been designed to minimise the impacts on the root system of the trees, whilst providing the highest level of permeability under the circumstances. The paving works include the following:

• Reinforced concrete crossover between the two subject trees. This has been selected due to the shallower profile and reduced need to excavate/lower grade.

• Permeable paving for the remainder of the car parking area. This can be installed with minimal change to the soil levels.

These paving works are not likely to cause any notable damage to the root system of these trees if correctly installed above grade with suitable permeable materials. Please refer to the paving guidelines at the end of the report for additional specifications. The final permeable paving specifications may need to be determined by an engineer, but should follow the general guidelines attached. Landscaping There are a range of landscaping activities that may cause harm to the soil and roots of the tree. These include but are not limited to; grade changes up or down, soil compaction from heavy machinery and stockpiling of materials, damage to tree trunks and branches from machinery, soil contamination from improper chemical use, root cutting from trenching activities for underground services (power and irrigation) and retaining walls, root damage from soil cultivation and planting and from paving activities. This can have an adverse impact on the long term health of a tree. The proposed landscaping works include the installation of minor swales, as well as planting out with a range of Australian native and locally indigenous plant species. Earthworks for the swales must be kept to a minimum, must cease when woody roots are encountered and should be done in consultation with the project arborist. Landscaping activities should follow the attached guidelines. Fencing Fencing works on the boundaries of the property within the TPZ must not use continuous trenching, as would be the case for a masonry wall, concrete plinth or other similar fence construction. It is recommended that boundary fencing at the site use lightweight panel fencing on a post and rail support system with concrete pads to support the posts. Fines Regulated and/or significant trees cannot be removed or damaged without development approval. Failure to adequately protect these trees may constitute a tree damaging activityn, which can attract fines of up to $120,000.

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If all of these strategies to minimise the impacts on the tree are observed, there will be a minimal impact on the long term health of the tree. These guidelines should form part of the Conditions of approval for the development of the site.

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Conclusion On the basis of my observations and discussion, I summarise my conclusions as follows:

• Tree Environs assessed two significant trees at 36 Main North Rd, Willaston in relation to an upgrade and change of use proposal for the site.

• Both trees are proposed to be retained, and require some pruning to improve tree form and maintain acceptable levels of risk at the site.

• A new driveway crossover and permeable paved car parking area are proposed, within the tree protection zones of both trees.

• The design solution for these surfaces has considered the needs of the trees, by minimising earthworks, using shallower profiles for the crossover and using permeable paving for the car parking area.

• Additional landscaping around the trees will assist in improving growing conditions for the trees.

• These works are not likely to adversely affect the trees if installed correctly with care. • A range of tree protection measures are outlined to ensure the impact on the trees is minimal.

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Recommendations

1. I recommend that both trees be retained on site and protected with a Tree Protection Zone (TPZ) as follows:

Tree 1 Tree 2 The TPZ radius from the centre of the trunk 15.0m 11.6m The TPZ area around tree 707m² 426m² The Structural Root Zone (SRZ) radius from the centre of the trunk

3.9m 3.4m

2. Protective fencing cannot be be set up around the significant trees due to site constraints.

Therefore, the following guidelines to protect the trees should be followed:

• Restrict vehicle access between the two trees whilst building refurbishment is occurring. Access to the building area should be from the adjoining land/car park area to the north.

• Restrict builders using the tree protection zone areas within the site for storage, material delivery, skip bins/waste disposal etc. This can be achieved with temporary fencing or bunting out to the extent of the tree protection zone within the subject site.

• This temporary fencing can then be removed to facilitate the installation of permeable paving and the concrete driveway crossover.

3. Site preparation/earthwork activities for levelling the site must proceed with caution under the

supervision of the project arborist, if permitted to occur within a TPZ. Site preparation activities should adhere to these guidelines.

• Remove temporary protective fencing to access the area for these works. • Limit site access within the tree protection zone/structural root zone for paving contractors and

landscaping contractors. Full site access between the trees can begin once paving works are completed.

• Works within the structural root zone/tree protection zone should be carried out after all relevant contractors have been briefed by the project arborist.

• To lower the soil levels and associated leaf litter layers between the trees within the structural root zone, works must be carried out by hand using light hand tools. The grade should be carefully lower until woody roots are encountered. This defines the lowest level the area can be reduced to. Consultation with the project arborist may be required during this stage.

• Outside the structural root zone (but within the tree protection zone) some lowering of soil levels and associated leaf litter layers can occur carefully by hand.

• The remainder of the low lying areas should be filled with a coarse aggregate that provides suitable load bearing capacity for the intended loads, whilst retaining high levels of permeability for the root system of the trees.

4. Where new underground services are required, these should be routed outside of the TPZ areas. If underground services must pass through a TPZ, they must utilise underground boring methods, hydro excavation or manually excavated trenches where tree roots are left intact and undamaged.

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5. Paving activities within a TPZ must minimise root damage by keeping earthworks to a minimum as outlined in recommendation 3 above. ß The reinforced concrete crossover between the two subject trees must be installed above

grade (after careful hand excavations and site levelling have been completed).

ß Permeable paving for the remainder of the car parking area must be installed above grade (after careful hand excavations and site levelling have been completed).

ß Refer to paving guidelines attached.

6. Landscaping activities must avoid disturbance to the root system. Refer to landscaping

guidelines attached.

7. Boundary fencing must use lightweight panels on a post and rail system (or similar) with no continuous trenching. Masonry fencing within any TPZ requires special design with arborist and engineers input.

8. The project arborist should be engaged to brief the project manager about tree protection

requirements, undertake inspections and provide certification at the following stages. a. Establishment of tree protection zones. b. Demolition stage. c. Site preparation and earthworks stage. d. Installation of underground services. e. Pre-construction stage. f. Construction stage (several visits may be required). g. Post construction stage. h. Landscaping stage.

As these two trees qualify as significant trees, an application must be made to your local council to approve this development in relation to this tree (including tree pruning and/or removals). While I believe the recommendations made above are the most appropriate to minimise the impacts on the trees, Council may take an alternative point of view and refuse consent. Development activities cannot occur until appropriate planning approvals have been granted from your local Council. These approvals must be shown to all contractors prior to commencement of works.

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Pruning I recommend the trees have the following pruning. Tree pruning works should occur prior to development activities commencing according to the pruning specifications below.

• All pruning must conform to the Australian Standard AS 4373 – 2007 Pruning of Amenity Trees.

• All pruning should be carried out or supervised by level 3 qualified and experienced arborists (or higher).

• Pruning must not be carried out by building contractors. Tree 1

• Remove dead branches over 40mm in diameter throughout the crown. • Lift lower crown within the site for suitable vehicle clearance (~4m above the ground), by

removing smaller primary and secondary branches only. Tree 2

• Remove dead branches over 40mm in diameter throughout the crown, including the large dead stem and remaining dead stub.

• Reduce leverage of the overextended branch in the upper crown to the east (below the dead upper section and overhanging the road) through reduction pruning by 30-50%.

This pruning is considered maintenance pruning and development approval may not be required. Council should be notified of such pruning to ensure they are satisfied that it is acceptable.

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Paving Works The installation of hard surfaces can include concrete, paving, bitumen etc. These can adversely affect a tree’s root system due to any of the following: Grade Changes

• Lowering of the soil level (cut) by as little as 50mm can remove tree roots, including fine non woody feeding roots that may not be clearly visible. This reduces root function which may adversely affect tree health.

• Severing of larger tree roots can encourage pathogens to enter a tree which may adversely affect tree health. Pathogens include fungi, bacteria, termites and other insects.

• Severing large roots close to a tree (within the structural root zone) has the potential to adversely affect tree stability which may result in whole tree failure.

• Increasing the grade (fill) can reduce soil oxygen levels in the existing root zone. This can affect root function and may result in root death. This in turn may have an adverse impact on tree health.

• The depth of base course preparations will vary depending on the intended load. Trafficable areas will require a deeper preparation while pedestrian areas can be shallower.

Soil Compaction • Excessive soil compaction increases soil bulk density, reduces soil pore spaces, reduces

moisture infiltration and reduces gaseous exchange. This can occur in the installation stage, and subsequently from regular vehicle movement.

Surface Sealing

• Impervious paving materials seal the surface above a root system reducing moisture infiltration and gaseous exchange between the atmosphere and root zone. Depending on the total area of the root zone affected, there may be an adverse impact tree health.

• Surface sealing of the root zone by structures and other impermeable surfaces should not exceed 20% of the total tree protection zone area.

Trees can damage hard surfaces

• Tree roots may cause movement of non-engineered surfaces as the root system enlarges. The design of the paved surface should take the possibility of root disturbance into consideration. All surface structures should be appropriately engineered where possible and be located at suitable distances from trees.

• Damage to concrete generally requires large areas to be repaired which can be more disruptive and expensive. Unit paved surfaces can undergo similar disruption as a result of root growth. Removal and replacement of only the affected sections facilitates easier and less costly repair work.

• The installation of hard surfaces should be restricted within the structural root zone to minimise future damage.

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Guidelines Where hard surfaces are required within the tree protection zone, a ‘tree friendly’ approach should be adopted. This aims to meet both the necessary engineering requirements, while at the same time creating an environment which meets the needs of the tree for healthy root growth and subsequent tree health. In recent years there have been a range of innovations in ‘tree friendly’ design, including ‘permeable pavements’, and ‘structural soils’. Permeable paving Permeable paving systems allow infiltration of air and water into the soil while still supporting pedestrian and vehicle loads. There are two main types of permeable ‘eco-paving’ systems:

1) Systems in which the pavers are made of impervious materials, but with air and water infiltrate through permeable gaps between pavers (e.g.Ecotrihex) or joints (e.g. Hydrapave).

2) Systems in which the paver is made of porous material, where air and water infiltrate through the paver itself and the joints between pavers (e.g. HydroSTON).

The profile for systems using impervious pavers with drainage joints will depend upon to the specific site conditions but typically comprise:

• 50mm or 80mm thick pavers (thicker pavers are required if vehicle loads are to be supported) with joints filled with 2-5mm clean aggregate.

• A 30-50mm deep ‘bedding layer’ of 2-5mm graded aggregate. A single-size (e.g. 5mm) bedding material may result in uneven pavers.10mm gravel is not recommended as it is very difficult to compact.

• Sand should not be used in the bedding layer or in any part of the permeable paving profile due to its very high clogging potential.

• A base course/drainage layer which allows stormwater runoff to drain freely from the paved surface, and infiltrate into the sub-base. The drainage layer is generally 100-300mm deep and comprised of 20mm graded and washed aggregate (no fines).

• A optional geotextile layer may be required between the basecourse and the subgrade, depending on the subgrade material (i.e. clay soils) to prevent fine particles migrating up from below.

• A geofabric layer is not recommended between the bedding and basecourse layers, as it can generate a slip plane and can also lead to accelerated clogging.

• All layers are to be compacted as per AS1289 MDD, however it is not always necessary to compact the sub-base, except in ‘weak’ bearing capacity soils such as marshland.

It should be noted that the above guidelines are indicative only and require civil engineering input, especially with trafficable pavements.

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Pavement installation practices Planning and design

1. Installation of the new pavement may require detailed root investigations, especially where work is to be undertaken within the Structural Root Zone. In this situation, carefully remove leaf litter layers and soil layers within the structural root zones until woody roots are encountered. Earthworks should cease at this point. This work should be carried out under the supervision of the project arborist.

2. Considering the finished paving levels in the design phase of the project. Aim to have the finished pavement level (and levels of surrounding structures) and all base course and bedding course preparations installed using the ‘no dig’ method. The finished levels of surrounding structures/surfaces may need to be adjusted to accommodate this.

3. Levels, cross-falls and excavation depths should be adapted to the presence of structural roots.

4. Preserve the soil structure at a suitable bulk density for root growth and function. Avoid excessive soil compaction.

5. Anticipate and cater for potential future growth of the trees root system wherever possible. Paving works very close to a tree are likely to be disrupted as tree roots enlarge. Paving should be restricted or reinforced within the structural root zone.

Installation

1. The project arborist should brief contractors where there is any pavement work within TPZs.

2. Permeable paving systems should be installed by contractors with experience in installing these systems. They should be supervised or briefed by the project arborist.

3. The soil surface should be carefully skimmed to establish a base for new paved surfaces.

a. Existing surface coverings should be removed carefully to avoid damage to roots just below the surface (such as existing paving and concrete).

b. The use of hand tools is recommended within the TPZ.

c. The use of a straight edge trimming bucket is recommended. The machinery should be standing outside the tree protection zone when establishing paving levels.

d. Lowering of grade should cease when any tree roots are encountered, including fine diameter non woody roots.

e. The natural soil level should not be lowered any more than 50-80mm.

4. The natural soil structure within the TPZ should be protected from compaction when installing hard surfaces. The natural soils below paved surfaces should not be compacted unless absolutely necessary (e.g. carrying heavy vehicle loads). Compaction of natural soils is not normally necessary for pedestrian or light traffic paving applications. Compaction levels will need to be determined by an engineer in consultation with the project arborist.

5. A geotextile fabric layer can be placed on the prepared natural ground level prior to applying the base course material. Geotextiles act as a filter between the subgrade and paving layers

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to prevent fine soil particles from the natural ground moving up into the base layers, causing them to clog.

6. It may be necessary to install a Three-dimensional load spreading products (Cellular Confinement Systems) such as ‘EcoCell’ or ‘Geoweb’. This is a system of cells into which the base material is placed. By confining aggregate infill, the system improves load distribution characteristics.

7. This base course material should then be compacted to suit the intended load according to the design specifications. Compaction should be to the minimum level required to support the intended load.

8. The bedding course should be applied directly on top of the base course.

o Geo-textile fabrics are no longer recommended between these two layers.

o The bedding course should use a single-graded aggregate to provide good porosity and permeability.

o Regular paving sand is not suitable for this application.

9. Permeable paving systems should have suitable permeability with open joints or gaps between pavers to allow moisture and gas exchange between pavers.

10. The unit pavers should have a single-graded aggregate swept in to fill in the gaps between pavers to ensure adequate air and moisture movement. Regular paving sand is not suitable for this application.

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Permeable paving design options While engineering requirements must still be met, design should be adapted where possible to accommodate existing tree roots, in terms of drainage layer thickness, excavation depth, and grades. Permeable paving allows some increased flexibility as surface runoff can be reduced, thereby lessening the need for traditional surface runoff issues. Any design solution will require:

• Civil engineering design, to meet required vehicle loads. • Tree root investiagtions to be conducted prior to construction.

Example - Permeable paving on aggregate base

• 80 mm pavers with 2-5mm aggregate filled joints. • 30 mm bedding layer (2-5 mm aggregate). • 200 mm drainage layer of 20mm washed crushed aggregate (100 mm minimum if structural

roots present in the top layers of soil). • Optional geotextile fabric layer (in clay soils).

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Landscaping around established trees Established trees may be damaged by a range of landscaping activities that encroach into their tree protection zone. These activities may include but are not limited to;

• Soil compaction from driving vehicles and/or machinery over the root zone, stockpiling of soils, storage of landscaping materials such as, pavers and other materials within the root zone will damage the growing environment and impede root growth.

• Mechanical damage from machinery operation or other landscaping activities in the vicinity of trees can damage tree roots, trunk, bark and branches.

• Soil contamination from careless use of cement products, herbicides, chemical spills etc.

• Trenching for footings, retaining walls, fencing, underground services and irrigation systems may sever tree roots, affecting tree health and stability.

• Grade changes for levelling garden and lawn areas and paved or concreted surfaces. The removal of roots by lowering grade can adversely affect tree health and tree stability. Adding soil can smother roots, reduce oxygen availability and reduce root function. Grade changes must be avoided.

• Driveways, roadways or formed pathways in the vicinity of trees can degrade the growing environment through sealing of the soil surface, and/or causing soil compaction. Materials used can contaminate the root zone. Careless installation can damage trunks, branches and root systems generally.

• Tree damage may result from machinery or people not experienced during tree pruning operations.

To minimise the possible adverse impacts from these activities during landscaping activities, a tree protection zone (TPZ) is required. The TPZ roughly equates to the drip line of the tree, but is accurately calculated in the body of the tree report. All potentially adverse activities must not occur within this zone or must be modified to minimise the impacts. Landscaping guidelines

1. The landscape design should be reviewed by the project arborist prior to being finalised.

2. Ideally, the area beneath a tree should have minimal hard landscaping. The landscape design should aim to provide the trees with ideal growing conditions so the trees remain a valuable asset at the site for many years. The root system requires access to air, moisture organic matter and minimal disturbance over as much of the root system as possible.

3. Prior to any works occurring, the landscaping team should meet on site with the project arborist to review work procedures, access routes, storage areas, parking areas and tree protection measures.

4. The removal of existing unwanted vegetation in the vicinity of established trees should be carried out manually with hand tools, not heavy machinery.

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5. Removal of larger trees should be carefully dismantled by qualified arborists.

6. The growing environment for mature trees should be optimised. The area under each tree should have a 75-100mm layer of coarse structured well composted mulch applied. Mulches should have a mixture of particle sizes such as wood chip and leaf. Fine textured highly processed mulches should be avoided. Mulches generated by tree removals on site could be used. This must be spread by hand, or lightweight machinery. Mulches should extend out to the edge of the drip line if possible. If not, consider mulching as large an area as possible. This mulch will add organic matter to the soil, add nutrients, help to improve soil moisture retention, encourage beneficial soil micro-organisms, reduce soil moisture evaporation and help to suppress weeds. Mulch should be topped up every 1-2 years or as required.

7. Avoid soil compaction within the tree protection zone. Prevent heavy machinery, compactors and vehicles from accessing the area. If they must access the area, ground protection measures are required.

8. Take extreme care when using herbicides in the vicinity of established trees. Target the undesirable plants carefully and follow manufacturer’s recommendations. Avoid using herbicides where rain or wind is expected.

9. A defined storage area for landscaping materials should be marked out well away from any TPZ.

10. A car parking area for contractors should be marked out well away from any TPZ.

11. If an access point passes over the TPZ a temporary protective roadway is required. This is achieved by placing a layer of geotextile fabric on the natural ground, then a 100mm+ thick layer of mulch with load bearing timbers/track mats placed on top.

12. All tree pruning should be carried out by qualified arborists.

13. Underground services should be installed outside the TPZ. If they must pass through a TPZ, underground directional boring or manual trenching is required. Tree roots larger than 30mmØ should be left intact.

14. Fences and retaining walls must not use continuous strip footings. Pier and beam, post and pad methods or similar must be used to bridge across the root system.

Planting considerations

1. Cultivation of the area under the tree should be kept to a minimum and undertaken with hand tools.

2. Changes in ground level within the root area of established trees should be avoided. Do not build up soil levels by more than 100mm in the vicinity of established trees.

3. Under-planting of competitive plants should be kept to a minimum. Minimise the use of turf, dense groundcovers etc.

4. The future size of larger plants and trees should be considered carefully. Plants should be well spaced considering their future growth habit and size.

5. Select the largest trees for the size available. Larger trees provide greater benefits than smaller trees.

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6. Provide adequate growing area for the trees to grow in. Small openings in paved areas may not provide the tree with its necessary requirements.

7. Species diversity is important in maintaining tree health. While monoculture plantings may provide a desired aesthetic, they are generally more vulnerable when pest and disease issues occur.

8. Consider when to use shade trees or deciduous trees in relation to building orientation, the movement of the sun and the placement of windows.

9. The use of locally indigenous plants should be considered for their habitat, biodiversity and wildlife corridor value.

If you have any further queries regarding issues raised in this report please feel free to contact me. Yours sincerely

Michael Palamountain B.Sc., Dip. Hort. (Arboriculture) ISA Certified Arborist (AU007A) Member: ISA, Arboriculture Australia, SASA Tree Environs Pty Ltd.

(m) 0412 174 507 (e) [email protected]

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mailto:[email protected]



Endnotes a Tree and risk assessments can be conducted at different levels and may employ various methods and tools. The level of assessment applied should be appropriate for the circumstances.

Level 1 - Limited visual assessment.

• A visual assessment from a specified perspective, near specified targets. • The aim is to identify obvious defects or specified conditions. • Typically identifies trees with imminent or probable likelihood of failure. • This is the fastest and least thorough form of assessment intended for larger populations of

trees. • This can be carried out as a walkover, drive-by or fly-over inspection.

Level 2 - Standard assessment.

• A level 2 assessment is a detailed ground based visual tree inspection of a tree and its surroundings.

• The use of simple tools (mallet, binoculars, probes, spades), may be required. • In some instances only limited information may be gained on specific internal, below ground or

upper crown factors. • For the majority of tree assessments the standard assessment provides adequate information

to guide tree management. Level 3 - Advanced assessment.

• A level 3 assessment is performed to provide detailed information about specific tree parts, defects, targets or site conditions.

• This assessment is usually conducted after a standard assessment has undertaken if additional information is required and with the approval of the client.

• Specialised equipment is often required for advanced assessment. • The assessments are generally more time intensive and expensive. • Advanced assessment techniques may include; aerial inspection, detailed target analysis,

detailed site evaluation, decay testing, health evaluation, root inspection, tree stability monitoring and load testing.

NOTE: If tree condition cannot be adequately assessed at the specified level a higher level of assessment may be required.

b A visual tree assessment (VTA) is an analytical process undertaken by a qualified Arborist or other suitably trained person to determine the structural soundness of a tree. Biological and mechanical components of trees are assessed, including tree health; presence of pests and diseases, die-back, foliage density and distribution, and vitality; growth rate, wound wood development, capacity to respond to improved conditions. Mechanical components include trunk lean, crown bias, bark inclusions, wounds, hollowing, trunk bulges, ribs, cracks, branch form, failure history, pruning history, condition of trunk flare, and other existing defects. All these factors are examined to determine if internal weaknesses may be present. If abnormalities are detected, we may conduct further investigations using a range of tools. These include sounding mallets, long thin drill bits, Resistograph, Sonic Tomograph, Air spade and other tools as required. Ref: Mattheck. Claus & Breloer, Helga. The Body Language of Trees. A Handbook for Failure Analysis. Department of the Environment. London 1997. c Boland, D., Brooker, M., Chippendale, G., Hall, N., Hyland, B., Johnston, R., Kleinig, D., McDonald, M. and Turner, J Forest Trees of Australia - Fifth Edition CSIRO Publishing 2006 and Centre for Plant Biodiversity Research (2006)- Contributors: AV Slee, MIH Brooker, SM Duffy, JG West EUCLID – Eucalypts of Australia Interactive CD ROM. Nicolle, D (1997). Eucalypts of South Australia.

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d Diameter at Breast Height (DBH) is the diameter of the trunk measured at breast height. This measurement is taken at 1.40m above ground level. This is the nominal point measured to determine Tree Protection Zones using the Australia Standard method AS 4970-2009 Protection of trees on development sites. When calculating a DBH for a tree with multiple trunks, the combined DBH do not accurately represent the root volume or area and the TPZ becomes exaggerated. Combining DBH in the following formula results in a revised total DBH that better represents the total stem cross sectional area as if it were 1 stem. From this a more proportional TPZ can then be calculated.

Combined DBH = √ (A² + B² + C² etc.)

(A, B and C etc. are the DBH of each individual stem) e The Tree Protection Zone (TPZ) radius is calculated by multiplying the trunk diameter at 1.4m by a factor of 12. The radius is measured from the centre of the trunk at ground level. A TPZ should not be less than 2m nor greater than 15m (except where crown protection is required). This method is outlined in the Australian Standard AS 4970 – 2009 Protection of trees on development sites. f TPZ area = πr² g The Structural Root Zone (SRZ) is the area around the base of a tree required for the tree’s stability in the ground. The woody root growth and soil cohesion in this area are necessary to hold a tree upright. The SRZ is nominally circular with the trunk at its centre and is expressed as a radius in metres. This zone considers the tree’s structural stability only, not the root zone required for the tree's vigour and long-term viability, which will usually be a much larger area. There are many factors that affect the size of the SRZ (e.g. tree height, crown area, soil type, soil moisture). The SRZ may also be influenced by natural or built structures, such as rocks and footings. An indicative SRZ radius can be determined from the following formula. Root investigations may provide more information on the extent of these roots. From AS 4970-2009 Protection of Trees on Development Sites.

SRZ radius = (Dx50)0.42 x 0.64

(D= trunk diameter in metres when measured above the root buttress) Any work within the SRZ should be avoided. Where no alternative exists, the work must be supervised by a qualified Arborist and approved by Local Council. Tree removal may be required depending upon the size and number of roots affected. h Eucalypt Longicorn Beetle - Phoracantha spp., commonly known as Borers, are host specific beetles that feed on living or dead gum trees. The adult beetles have very long segmented antennae that are directed backwards over their elongated and cylindrical body. The larvae are white tapering grubs with large dark brown head with strong mandibles. The larvae bore mainly under the bark of the lower trunk feeding on the cambium layer. In severe attacks the trunk may be ring barked causing the death of the tree. They pupate inside the wood. When they hatch, the adults cut emergence oval shaped holes through the bark. Naturally, they may occur in small numbers in healthy trees. They can increase in numbers in trees that are stressed or unhealthy for a wide variety of reasons (incompatible with climate, poor pruning history, root disturbance, poisoning etc.). i Branching order describes the divisions between successively smaller branches in a tree. The main trunk is what emerges from the ground and is not considered a branch. First order branches (or primary branches) emerge from the main trunk and are the main scaffold branches of the tree. Second order branches (or secondary branches) emerge from these first order branches, followed by third order branches (tertiary branches) and so on. Successive branching is usually characterised by a reduction in branch diameter at each division. Draper, D and Richards, P. Dictionary for Managing Trees in Urban Environments CSIRO Publishing and Institute of Australian Consulting Arboriculturalists 2009.

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j Lopping or topping is the practice of cutting branches or stems between branch unions or internodes. This is an unacceptable practice for the following reasons.

a) Lopping increases the rate of shoot production and elongation. b) The resulting regrowth is weakly attached and becomes prone to failure or collapse. c) The stubs that remain may decay d) The natural habit of the tree is destroyed. e) Lopping may reduce the lifespan of the tree f) This type of pruning predisposes trees to fungal infections and insect attack.

From Australian Standard AS 4373-2007 Pruning of amenity trees section 8.1 k Epicormic regrowth arises from dormant buds beneath the surface of the bark. These buds are stimulated to grow following heavy pruning, branch death, storm damage, during recovery periods or after stressful events such as plagues of defoliating insects, fire, mechanical wounding or poor growing conditions. They occur as a response by the tree to stress and are intended to rapidly provide renewed leaf area for photosynthesis and the production of carbohydrates. Epicormic shoot growth also occurs during the process of tree decline as limbs die or fail and crown size diminishes. The strength of attachment of epicormic stems is often less than that of normal limbs. Where epicormic growth occurs in response to lopping or storm damage, the competing stems can prevent development of sound structural characteristics and may require specialized Arboricultural management over an extended period to improve tree form and minimise risk. l Centre for Plant Biodiversity Research (2006)- Contributors: AV Slee, MIH Brooker, SM Duffy, JG West EUCLID – Eucalypts of Australia Interactive CD ROM m It may be possible to encroach into or make variations to the standard Tree Protection Zone (TPZ). Encroachment includes excavation, compacted fill and machine trenching. Minor encroachment - If the encroachment is less than 10% of the TPZ area and is outside the Structural Root Zone (SRZ), detailed root investigations should not be required. The area lost to this encroachment should be compensated for elsewhere and contiguous with the TPZ. Variations must be made by the project arborist considering relevant factors listed on section 3.3.4 of the standard. Major encroachment - If the proposed encroachment is greater than 10% of the TPZ area or inside the SRZ, the project arborist must demonstrate that the tree would remain viable. The area lost to this encroachment should be compensated for elsewhere and contiguous with the TPZ. This may require root investigation by non-destructive methods and consideration of relevant factors including: location and distribution of roots, the potential number and size of root loss, tree species and tolerance to root disturbance, age, vigour and size of tree, lean and stability of the tree, soil characteristics, volume, topography and drainage, the presence of existing or past structures or obstacles and design factors. From Australian Standard AS 4970 – 2009 Protection of trees on development sites, section 3.3. n tree-damaging activity means (a)the killing or destruction of a tree; or (b)the removal of a tree; or (c)the severing of branches, limbs, stems or trunk of a tree; or (d)the ringbarking, topping or lopping of a tree; or (e)any other substantial damage to a tree, and includes any other act or activity that causes any of the foregoing to occur but does not include maintenance pruning that is not likely to affect adversely the general health and appearance of a tree or that is excluded by regulation from the ambit of this definition; (From section 4 - Interpretation of the Development Act 2003) Development Regulations 2008 Section 6A (8) For the purposes of the definition of tree damaging activity in section 4(1) of the Act, pruning— (a) that does not remove more than 30% of the crown of the tree; and (b) that is required to remove— (i) dead or diseased wood; or (ii) branches that pose a material risk to a building; or (iii) branches to a tree that is located in an area frequently used by people and the

branches pose a material risk to such people, is excluded from the ambit of that definition.

Page 88 of 210

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