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Protecting existing trees Protecting existing trees and new buildings on and new buildings on development sites.development sites.

Engineers Australia Engineers Australia South West Group South West Group -- Victoria Division Victoria Division Warrnambool Warrnambool -- February 2012February 2012

By Jenny Boyer By Jenny Boyer -- Rootology Pty LtdRootology Pty LtdThis is achievable through good planning and designThis is achievable through good planning and design

To protect trees and buildings, carry out To protect trees and buildings, carry out an Vegetation Site Survey at the begining an Vegetation Site Survey at the begining --

Locate all trees on the subject siteLocate all trees on the subject site

Locate all trees on neighbouring propertiesLocate all trees on neighbouring properties

Locate all council and park treesLocate all council and park trees

Measure each tree; canopy NMeasure each tree; canopy N--S & ES & E--W, height, DBHW, height, DBH

Site features; surface water, buildings, Site features; surface water, buildings, above & below ground servicesabove & below ground services

Spot heights of ground, including trees, excavationsSpot heights of ground, including trees, excavations

Number each treeNumber each tree

When building on a site with existing When building on a site with existing trees, there are two questions to be trees, there are two questions to be considered considered --

1. What impact will the new building 1. What impact will the new building have on the existing trees?have on the existing trees?

andand

2. What impact will the existing trees 2. What impact will the existing trees have on the new building?have on the new building?

To control the impact of the new building To control the impact of the new building on the existing trees, manage the on the existing trees, manage the --

Canopy Canopy --

Pruning in to dead woodPruning in to dead wood

••Crown thinningCrown thinning

••Pruning symmetrical treesPruning symmetrical trees

••Pruning asymmetrical treesPruning asymmetrical trees

••Remember Remember -- this is relevant to trees on the subject this is relevant to trees on the subject AND neighbouring sitesAND neighbouring sites

To control the impact of the new building To control the impact of the new building on the existing trees, manage the on the existing trees, manage the --Root system Root system --

Extends laterally 1 Extends laterally 1 -- 3 x the height of the tree3 x the height of the tree

••Extends vertically Extends vertically -- determined by species & soildetermined by species & soil

••4 4 -- 10 structural roots10 structural roots

••Severing large and/or small roots within safe limits Severing large and/or small roots within safe limits can be catastrophiccan be catastrophic

••Loss of an asset, monetary penalties or finesLoss of an asset, monetary penalties or fines

••Damage to property or people, legal actionDamage to property or people, legal action

••Remember Remember -- this is relevant to trees on the subject this is relevant to trees on the subject AND neighbouring sitesAND neighbouring sites

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Protecting existing trees Protecting existing trees duringduringthe development the development --

Be vigilantBe vigilant

Significant damage cannot be repairedSignificant damage cannot be repaired

•• Tree Protection Zones (TPZ’s) protect the above Tree Protection Zones (TPZ’s) protect the above and below ground sections of the treeand below ground sections of the tree

•• Remember Remember -- this is relevant to trees on the subject this is relevant to trees on the subject AND neighbouring sitesAND neighbouring sites

TPZ for a Symmetrical TPZ for a Symmetrical TreeTree

Diagram drawn by Jenny Boyer for the Australian Standard AS 4970 ‘Protection of trees on development sites’.Diagram drawn by Jenny Boyer for the Australian Standard AS 4970 ‘Protection of trees on development sites’.

TPZ for an Asymmetrical TPZ for an Asymmetrical TreeTree

Diagram drawn by Jenny Boyer for the Australian Standard AS 4970 ‘Protection of trees on development sites’.Diagram drawn by Jenny Boyer for the Australian Standard AS 4970 ‘Protection of trees on development sites’.

Protective Fencing of the Protective Fencing of the TPZTPZ

Diagram drawn by Jenny Boyer for the Australian Standard AS 4970 ‘Protection of trees on development sites’.Diagram drawn by Jenny Boyer for the Australian Standard AS 4970 ‘Protection of trees on development sites’.

Branch, trunk & root protection Branch, trunk & root protection (when encroachment within the TPZ is (when encroachment within the TPZ is necessary)necessary)

Diagram drawn by Jenny Boyer for the Australian Standard AS 4970 ‘Protection of trees on development sites’.Diagram drawn by Jenny Boyer for the Australian Standard AS 4970 ‘Protection of trees on development sites’.

Trenching along the Radii Trenching along the Radii (when encroachment within the TPZ is (when encroachment within the TPZ is necessary)necessary)

Diagram drawn by Jenny Boyer for the Australian Standard AS 4970 DRAFT of the ‘Protection of trees on development Diagram drawn by Jenny Boyer for the Australian Standard AS 4970 DRAFT of the ‘Protection of trees on development sites’.sites’.

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Trenching along the Radii Trenching along the Radii (when encroachment within the TPZ is (when encroachment within the TPZ is necessary)necessary)

Diagram drawn by Jenny Boyer for the Australian Standard AS 4970 DRAFT of the ‘Protection of trees on development Diagram drawn by Jenny Boyer for the Australian Standard AS 4970 DRAFT of the ‘Protection of trees on development sites’.sites’.

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Protecting existing trees Protecting existing trees postpostthe development the development --

Water Water -- restrictionsrestrictions

Storm, grey or recycledStorm, grey or recycled

•• Regular Regular -- storage facilitystorage facility

•• Deep Watering Points (DWP’s)Deep Watering Points (DWP’s)

-- 500mm to 2 500mm to 2 -- 3 meters deep depending on soil3 meters deep depending on soil

-- Avoid roots 20mm+ in diametreAvoid roots 20mm+ in diametre

-- Slotted pipe inside micropore geotextile sleeveSlotted pipe inside micropore geotextile sleeve

-- Network of pipes from water sourceNetwork of pipes from water source