Think Beyond the CorridorOptimising Tree Planting Opportunities for Infrastructure CorridorsPaul Geehan AECOM with Mark Blanche and Stephen Callaghan

Potential for Urban ForestsRail Roads Water

CatchmentsInter City (HSR) Motorway (OSO,

WestConnex)Trunk Catchment(Rouse Hill)

Metropolitan (SydneyMetro)

Arterial Naturalisation(Cooks River)

Urban/Clearway andDuplication

Local WSUD (Localdevelopment)

OpportunitiesUrban Infrastructure within metropolitan SydneyApprox 160 kms motorway (average 80m wide)Approx 1000 kms of rail corridor (average 60m wide)73 Catchments, 440km Stormwater Trunk Channels

Motorway Corridor with good ‘fit’ beyond corridor (City Link Melbourne, AECOM)

Motorway Corridor with landscape amenity beyond corridor (Yorks Hollow, Brisbane, AECOM)

Ability to provide a good ‘fit’ is often limited by corridor width, resulting in poorly landscapebatters such as this (M7 Sydney, AECOM)

BIG NUMBERSBig projects/$BillionsCompetition for Millions of PlantsConventional ProcurementStrategies cannot copeWe need to think to ‘Think Beyondthe Corridor’?

Motorway Corridors often highly defined at edges, with no ‘fit’ beyond corridor (Monash FreewayMelbourne, AECOM)

Non-Integrated Infrastructure• Roads and rail corridors are typically delivered as narrow linear

corridors - isolated elements within their landscape• Primarily determined by operating requirements and corridor

easements• Landscaping is cut off at project boundaries, stormwater is usually

sent down the nearest pipe• As such it is often difficult to achieve a good ‘fit’

Integrated Infrastructure• Lately we have been blurring the edges• For example, we now use a range stormwater treatments devices to

disconnect infrastructure corridors from receiving waters:• Swales• Bioretention systems• Wetlands

Integrated Infrastructure

WSUD Rain Gardens, Crace, ACT

Integrated Infrastructure

Motorway Corridor detention basin beyond corridor (Yorks Hollow, Brisbane, AECOM)

Integrated Infrastructure• We are also developing alternatives to traditional approaches to

providing topsoils and plant material• For example :

• Topsoil Translocation• Comprehensive soil horizon testing/soil chemistry• Soil Management Strategies• Direct seeding

Three Case Studies• Hunter Economic Zone• Rouse Hill Detention Basins• Moorebank Defence Logistics Centre

Hunter Economic Zone

Translocation of bushland soil

Site Investigation• What is the soil resource?

• How much topsoil is there?

• What are the different soil types?

• Chemical and physical characteristics by soil horizon

• Soil constraints?

• Soil opportunities?

We are not a soils specialists

Typical core team:

• Soil science / agronomy

• Native seeding specialist

• Bush regenerator

• Accompany soil scientist on site investigation inspection

• Collaborative design approach

• Hunter Economic Zone3,300 ha bushland site south of Kurri Kurri5 Endangered ecological communities800 ha Designated for industrial hubRemainder into conservation

Proposed Road Corridor (Artist impression, AECOM)

Summary of Issues• Early landscape works:

• Site soils difficult to ameliorate

• 100mm imported topsoil over ameliorated site soil

• Non-locally occurring species

• Landscape failing to thrive

• Weed colonisation

• Process becoming unsustainably expensive to implement andmaintain

Steep batters as always a limiting factor in restoration potential

Road projects – steep battersBatter slopes:

– Ideally 5H:1V

• Facilitates machine access

– Often 2H:1V

• Smooth batters / hostile subsoils / slumping

• Planting difficult / most commonly seeded

• Nitrogen drawdown

• Tannins

• Difficult to manage - OH&S

100 mm Bio-layer

A1 Horizon varies

A2 Horizon varies

HEZ Soil Translocation Donor Soil Stripping, Stockpiling and Re-placement based on adetailed analysis of soil horizons that match seed bank

HEZ Topsoil stripping sequence

Hunter Economic Zone – topsoil stripping locations

Hunter Economic Zone – topsoil stripping locationsHEZ Soil Translocation Donor Soil Stripping, Stockpiling Locations

Hunter Economic Zone – topsoil reinstatement locationsHEZ Soil Translocation Typical Donor Soil Re-placement locations to design condition

HEZ Soil Translocation verge results

Bush regeneration

Key study resultsResulting landscapes• levels of native species richness, diversity and evenness as high

as pre-clearing reference sites• No obvious trends related to length of delay in restoration• Of 192 native species recorded within the reference sites, only 6%

were not detected following topsoil translocation

Rouse Hill Landscape Restoration

Key initiatives• Topsoil stripping and reinstatement

• Mass planting

• Direct seeding

• Bushland soil translocation

Basin 32

Basin 31

Basin 33

Basin 35

Key design issues• Hostile subsoil conditions• Lack of conveyance / storage capacity

• Landscape restoration process

Bush regeneration

Bush regeneration

Key design tools• Soil stripping / reinstatement• Basin / channel design• Restoration process

• Provenance plant material• Species diversity• Planting densities• Weed management• Long term management

Soil stripping and reinstatement

Contractor training

Direct seeding; Drilling machine

Direct seeding; seed in plough line (pink)

Restoration communities

Monitoring

Basin 32 outlet, looking across floodplain to Basin 32

Installation

Basin 31 outlet, looking across floodplain to Basin 32

15 months

Basin 32 outlet, looking across floodplain to Basin 32

30 months

Direct seeding trial

• With and without an application of surface compost• With and without applications of broadleaf herbicides• Testing for the species Sorghum leiocladum, Capillepedium, Spicigerum,

Bothriochloa macra, Austrostipa ramissisima, and Themeda australis• 10 treatments, 4 replicas, 40 plots in total• Measurements of density and cover abundance 4 times per year

over 2 years

Restoration outcomes• Species diversity• Resilient / self-regenerating communities• Soil amelioration / stability• Long-term low maintenance• Scenic amenity• Climate amelioration• Infrastructure as ‘bushland’

Translocation of bushland soil

Defense Logistics Centre, Moorebank NSW

Building on lessons learnt at HEZ and Rouse Hill

Re-Growth area (seed bank) suitable for translocation

Site Stripped and stockpiled

Translocated Re-growth

Detention Basin

Construction phase complete

Landscape outcomes• Planting of mixed species basins with 110,500 trees, shrubs

and ground covers (approximately 40 differentspecies) covering a total area of 15,600m2

• Improved amenity and access for community with DefenceLand in creek corridor; gifted community park corridor

• Increased biodiversity and amenity with regeneration of thecreek corridor

• Use of regrowth on area of site that was to be developed forDefence purposed – translocation process

• Extension of habitat into the Defence Area with mixed speciesdetention basins (instead of defence usual approach of turfbasins only)

• Thinking beyond boundary line and ownership issues resultedin a win-win for Department of Defence, the community andthe environment.

Ring of Ponds

Think Outside the CorridorLandscape architects need to be closely involved with soils,

• Regular need for specialist advice, with providers having oftechnical knowledge and practical know-how

• Ability to provide sustainable, innovative and cost effectiveoutcomes for often very difficult problems

Typical collaborative team:

• Soil science / Native seeding specialist/ Bush regenerator• Working beyond the infrastructure corridor requires collaboration

and partnership, sometimes beyond project boundaries• This approach need to be adopted early in the planning stages of

projects

Thank you