Citygreen Specifier Update 18

SPECIFIERUPDATE

ISSUE 18

Contents CASE STUDIES

2 Civic District, Singapore4 Lonsdale Street6 Mackay City Centre

8 Calgary Alberta11 Kent Street Cycleway

EBOOK

14 Conservation of our Urban Forest Health and Sustainability

T he Civic District is the birthplace of modern Singapore

and marks the beginning of the country’s historical,

architectural, and cultural heritage. Plans for the Civic

District enhancement works were revealed during the Draft Master

Plan 2013 exhibition and were completed in phases by the end of

2016.

As part of the enhancement works, a new row of beautiful na-

tive Kayu Arang (Cratoxylum cochinchinense) trees were planted

along Queen Elizabeth Walk at Esplanade Park and in front of the

Asian Civilisations Museum at Empress Place. Complemented with

stepped plazas along the edge of the Singapore River, this area

brings people closer to the scenic waterfront view.

Prior to the establishment of the trees, considerations were made

during the design stages on tree root management solutions that

enable trees to thrive in a complex urban environment where there

is a constant flow of pedestrian traffic.

Leading urban landscaping management solutions provider, El-

mich, introduced Citygreen’s Stratavault solution, an advanced

structural root cell engineered to keep trees healthy by prevent-

ing soil compaction caused by building structures thus providing

Stratavault enlivens Civic District in Singapore

Installation of soil vault

Continuous, engineered soil vault by Citygreen, supporting pavement.

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adequate breathing space for healthy root growth. The root cell

is made entirely from 100% recycled polymers and is a proven

system which builds on the experience gained through trials,

projects, and collaborations with industry innovators worldwide.

The tree root management system features huge openings and a

patented nesting ability for easy installation, higher strength, re-

duced transport costs, and maintenance of large spaces for root

growth and service integration.

Take a walk around the Civic District and experience a feeling of

intimacy with history and lush greenery enhanced with pedestrian-

friendly landscaped spaces for the public.

Project Credits:

Developer/Owner: Urban Redevelopment Authority (URA)

Architect: Architects 61 Pte Ltd / Cox Architecture Pty Ltd

Landscape Architect: Context Landscape Design Pty Ltd

Arborculture Consultant: Arborculture Pte Ltd

Main Contractor: Shanghai Chong Kee Furniture and

Construction Pte Ltd

Completed museum plazaMuseum installation

Continuous soil vault system for healthy trees on the waterfront

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Citygreen® SPECIFIER UPDATE 3

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Lonsdale Street transformed into Melbourne green boulevard – with benefits to the bottom line

In the heart of Melbourne’s growing southeast corridor lies the

City of Dandenong. In 2010, a comprehensive ‘Revitalising

Central Dandenong’ initiative was launched by the Victorian

government through Places Victoria. Seeking to rejuvenate the

rundown Lonsdale Street precinct, a team of renowned Landscape

Architects, Engineers, and Builders came together to create a fresh

new future for the city.

Five years down the track, the project has proven to be an

overwhelming success, with Lonsdale Street now considered one

of Melbourne’s great boulevards. A green, pedestrian-friendly main

street encompasses the city’s vibrant retail industry with wider

footpaths, various urban furniture, bicycle stands, and – the jewel in

the crown – 251 thriving Pin Oak trees. In line with urban stormwater

best practice, there are also a number of rain gardens which capture

and treat stormwater, which is then reused for irrigation.

Today, the thriving streetscape looks as if it’s always been there,

belying the comprehensive engineering and technology below

ground that made it all possible. Whilst the original design specified

reinforced concrete slabs supported by streel screw piles over a

continuous soil trench, the suspended slab ultimately proved too

expensive due to poor ground conditions. Argot Consultants Pty

Ltd & KLM Spatial were engaged to investigate cost-effective

alternatives to piling, and after seeing several successful projects

in Auckland, New Zealand, Citygreen’s Stratacell product was

selected.

Landscape contractor Sugan Blanchard, of Canteri Bros

Construction Pty Ltd, said, “Argot Consultants Pty Ltd & KLM

Spatial came up with the Stratacell system, which provided cost

and time saving to the project. The main cost saving was on the

reduced thickness of the slab as it was designed as a slab on

ground instead of suspended slab. We had never used this system

before but found it to be easier to install and time efficient, providing

the structural strength to overlying pavement while allowing

uncompacted growth media for trees.”

Landscape Architect, Scott Adams, Director of Taylor Cullity

Lethlean, counts the Lonsdale Street project as one of the firm’s

landmark projects. Adams said, “The Lonsdale Street site proved

to be really challenging, and the Stratacell product was the solution

that got sign off from Argot Consultants Pty Ltd & KLM Spatial

Engineers. Thankfully, the project was completed on time and the

product hasn’t failed despite significant surface traffic. It’s definitely

been successful in generating the result we wanted, with the trees

performing well. As a result, we’ve recommended the product on a

number of subsequent projects.”

Found it to be easier to install and time

efficient, providing the structural strength

to overlying pavement while allowing

uncompacted growth media for trees

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Theo Niakolas, Principal Engineer at Argot Consultants Pty

Ltd, echoes this sentiment. “From our perspective, the project

has been a success, and the clear evidence is the health of

the trees. The cells have performed well in terms of providing

support to the hard stand paving above, as expected during

design. No adverse distress of the rigid pavement is evident.

We’ve since suggested the product in other streetscape

projects too numerous to identify.”

Today, Lonsdale Street is unrecognisable, transformed from

a grey, uninviting locale into a green, thriving streetscape for

residents, workers, and visitors to enjoy.

It’s definitely been successful in generating the

result we wanted, with the trees performing well.

As a result, we’ve recommended the product on

a number of subsequent projects.

Highly integrated stormwater management, treatment, and green canopy

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Designed and built over twenty years ago, the CBD

was aesthetically outdated and often subject to minor

flooding and drainage issues. The narrow sidewalk

was also unsuitable for al fresco dining, and failed to offer a social,

multi-faceted shopping experience. Through the revitalisation of

the CBD’s aesthetic and environmental qualities, Mackay Regional

Council sought to resolve these issues, and in turn promote local

and regional economic development.

Dave Watt, formerly Landscape Project Manager at Vassallo

Constructions, said, “The primary goal was to increase public

access and better utilise the area while beautifying it and displaying

some of Mackay’s existing features such as the many art deco

period buildings. The project also enabled the upgrade of services

to the area.”

Ben Ewins, formerly Landscape Architect at RPS Australia Asia

Pacific, said, “Once Mackay Regional Council had confirmed the

preference towards using Hill’s Weeping Fig Trees (Ficus microcarpa

var. Hillii) in the central medians, we identified a disparity between

this species and the prospective available root space and volume.

Ultimately, we needed a solution that would allow the trees to grow

by creating a greater volume of space below the road pavement for

root growth, without encroaching on the proposed civil works.

Ewins said, “To achieve this, we required a sturdy support

mechanism that would facilitate a number of outcomes:

1. Support significant road pavement vehicle loads

2. Prevent compaction of the soil / root zone

3. Achieve a high ratio of support structure soil volume

4. Address the concerns about warranties.”

Mackay City Centrerevitalised with strikingHill’s Weeping Fig TreesIn August 2014, a significant overhaul of Mackay’s City Centre commenced, known as the City Centre Revitalisation Project. This tropical CBD resides along the Pioneer River, and houses the bulk of Mackay’s hospitality and commercial businesses.

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Manager – City Centre Revitalisation at Mackay Regional Council,

said, “This project was a hard sell, because historically there are

problems with underground infrastructure being ripped up by figs

and other big trees. Thankfully, Stratacell allowed us to kill two birds

with one stone – providing a nice big volumetric space for healthy

root growth, and providing a barrier to stop roots going further

and causing damage. Essentially, it provides a giant planter box

underground.”

Watt said, “Citygreen were the specified supplier, because their

products had the capacity to meet the complexities of the project.”

In fact, Citygreen’s Stratacell system was the only product that

delivered the required structural integrity needed for this application.

Watt continued, “Citygreen’s products have been tried and tested

on other projects. The products’ proven success provided us with

confidence that we’d achieve a positive outcome in the required

timeframe, and enabled different construction methods to be

investigated prior to implementing the best procedure.”

Ewins said, “The resulting outcome has been extremely positive

and all trees installed to date are in excellent health. The key benefit

of working with Citygreen was without a doubt their immediate

response times in providing solutions and inputs to what was a

critical situation, which required a fast turnaround. Their expertise,

along with the fast turnaround, was invaluable.”

Watt said, “A positive outcome has been achieved, with both the

public and business owners in the area very upbeat about the end

result. Using Citygreen technologies also provided us with confidence

that there will be no rectification works required and we can be sure of

longevity in this striking-looking project. We’re proud to have played a

part in providing long-lasting satisfaction for the local community and

visitors to the area.”

Rob Guthrie, Principal – Landscape Architecture at RPS Australia

Asia Pacific, added, “The trees are growing, and the system is proving

to work well for us. Citygreen were excellent to work with, providing

lots of helpful information on the product and assisting us to convince

council to proceed. I’d absolutely recommend them to others.”

Carless concluded by saying, “So far, the trees are performing well

with minimal leaf drop. We’re confident we’ll continue to see good

growth rates, without any damage to surrounding infrastructure.

Citygreen were great to work with, with helpful technical people who

gave us lots of information, and were really involved leading up to

construction. I couldn’t fault them, and would definitely recommend

them and this solution to other organisations that have a similar

challenges.”

Magnificent growth, with engineered soil vault

beneath road pavement

Excellent canopy after 2.5 years

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One of the City of Calgary’s 2016 urban construction

projects is Thomson Family Park, on 1236 16th Ave

SW. This park, designed by Ground Cubed and EXP

Engineering, replaces a bowling green with a multi-purpose park

aimed at the widest possible neighborhood demographics.

Along 11th St SW is a broad sidewalk, interspersed with street trees.

These trees will grow through beautiful tree grates and pavers, to

provide shade and visual interest along the street.

Living off the street…

These trees are watered by stormwater that’s fed through catch-

basins and a system of distribution pipes into the StrataVault soil

cells. Heavy solids and particulate matter are filtered out in the

catch-basins to protect the trees as much as possible.

Stratavault installation

The soil cells were installed during May 2016, by Alpha Better

Landscaping. The photograph below shows the compacted

subgrade, with the sub-drain running centrally through the tree-pit.

The clean-out for this drain rises through the cells at the end.

Calgary Alberta usesStrataflow treepits forcoupling Green with BlueThomson Park advanced design for healthy trees and stormwater treatment

Image by Ground 3 Landscape Architects | http://www.ground3.com

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Stormwater Distribution

Once the base cells were in place and back-filled with soil, the

distribution pipes could be positioned, running along at 2 parallel

locations through the upper level of the cell matrix.

Stratavault offers very broad openings within the cell matrix, so a

200mm/8” pipe is an easy fit through the system, with no need to

remove any part of the cell structure itself.

Image by Ground 3 Landscape Architects | http://www.ground3.com

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Tree Openings

Another very attractive feature of the Stratavault system, is the ability

to maintain its structural integrity whilst removing sections of the cell

matrix. The pictures show how the contractor was able to create

the root-bole openings to match the position of the rectangular

tree-grate frame above. The system is still completely connected

around the opening, thus maintaining its integrity, and exceeding

the loading standards for downtown Calgary sidewalks.

Thomson Park will be a wonderfully healthy place to rejuvenate and

relax. But the infrastructure itself will also provide a natural means for

green infrastructure to thrive and beautify the area for generations

to come, while reducing the load on the City of Calgary’s municipal

sewer system.

Surely a Win-Win solution…!

Calgary is building beautiful green spaces, using Strataflow design

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Stratacell adds green touch to urban Sydney cyclewayThe final section of Sydney’s much-awaited Kent Street Cycleway is now open – completing a planned network of cycleways through the heart of the city. Used by around 1700 bike riders each weekday, the completed cycleway means people now have a safe north-south route between the Sydney Harbour Bridge and Darling Harbour.

Even in inner city, hostile environment -

excellent growth after 2.5 years

The cells provide an ideal solution for the installation of trees in highly-developed urban environments where there is not much room for construction, providing growing space for trees and their root systems without damaging pavements.

The support from Citygreen during the construction process enabled us to obtain the best outcome.

Trees at planting

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Between Liverpool Street and Druitt Street, the City of

Sydney – asset owner and local government authority

– sought to add some greenery to a primarily urban

setting. Complete Urban was engaged as the landscape architect

and project manager.

Juan Vargas, of Sydney Civil, said, “Design concepts from the

client required the planting of new tree species in an already

established environment. A solution was required to offer room to

the trees to grow but not affect the infrastructure constructed. The

main issue was the presence of underground services and limited

space available for the planting of the trees.”

Porous paving stones for environmental benefit

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Citygreen’s Stratacell system was specified as part of the design,

renowned for its ability to provide the soil volume required and

the room for roots to grow without impeding on or damaging

surrounding infrastructure.

Juan Vargas said, “The project was completed successfully. Whilst

the trees are still in a very early growing stage, no issues have

presented. The cells provide an ideal solution for the installation of

trees in highly-developed urban environments where there is not

much room for construction, providing growing space for trees

and their root systems without damaging pavements. The support

from Citygreen during the construction process enabled us to

obtain the best outcome.”

Trees at planting Sept 2014, compare growth illustrated in

images from 2.5 years later

Ultra-high strength Stratacell 60 system for intesive loading situations.

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An urban environment rich with trees is highly valued

for its aesthetic qualities as well as its environmental

benefits, such as reducing summer cooling costs,

carbon sequestration, intercepting airborne pollutants, reducing

storm water runoff and promote habitats for native wildlife. In

the United States, urban forests are estimated to contain about

3.8 billion trees, with an estimated structural asset value of $2.4

trillion (Nowak et al. 2002). Billions of federal, local and private

dollars are being spent annually on management, labor, and the

trees themselves as part of tree revitalization projects, and millions

more are being spent by individual homeowners to improve

their environment and property values. An important criterion for

selecting trees to be planted is diversity: biodiversity and genetic

diversity. Researchers of urban forestry refer to urban biodiversity

as the 10-20-30 rule (Galvin 1999; Santamour 1990).

This rule states that not more than 10% of the urban forest should

be of the same species, no more than 20% should be of the same

genus, and no more than 30% should be of the same family.

Genetic diversity refers to the diversity or genetic variability within

a species. Each individual species possesses genes which are the

source of its own unique features. Similary, human beings are all

the same species but we all look different from each other. A lack

of genetic diversity in individual species of trees reduces the genes

available; as a result, unique features of the species are no longer

present, even its resistance to diseases and thereforeindividuals

looks alike. Genetic diversity is epically important for trees because

of their long live spans and the unpredictability of future pests,

pathogens, climate, and environmental quality. By selecting tree

composition for the maximum biodiversity and genetic diversity,

the trees will have a greater chance of surviving for longer periods.

Unfortunately, the last few decades have seen a movement in

the opposite direction: cultivation in order to achieve uniformity.

Recently, some biodiversity measures have been implemented;

however, despite this multi-billion dollar urban tree economy , little

work has been done to understand urban tree genetic diversity

as an issue of vulnerability, or to examine the long-term impacts

of urban tree genetic diversity on the sustainability of the urban

environment.

Work conducted by Cynthia Morton, PhD and Phil Gruszka, in

2008, compared the level of genetic variation in London Plane

trees already existing in the Pittsburgh area with trees of the same

species currently available from three commercial nurseries. The

genetic diversity was far greater in the older urban tree samples

compared to that of the nursery samples, indicating that the

nursery industry has been selectively cloning to produce new

trees. While cloning trees is in itself a benign practice, doing so on

a mass scale without a proper understanding of the implications

of drastically reducing the genetic diversity of urban forests is ill-

advised and potentially creating an area for natural disaster.

Conservation of our Urban Forest Health and Sustainability via Tree Genetic Diversityby Cynthia Morton and Phil Gruszka

14 ISSUE 18

EBO

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Morton and Gruszka’s initial research led to enquiries for

information about other commonly-grown nursery tree species

and cultivars. The paper entitled “Popularity of tree species and

cultivars in the United States” (Nowak 1992 and updated in 2006)

lists the top ten species sold by nurseries in the United States and

in which major geographic region they are sold. Almost all (eight of

the top 10) of these nursery stock trees are grown throughout the

United States and not just in one or two regions.

In early 2010, Dr. Morton conducted a telephone survey

throughout the U.S. and discovered that most regional nurseries

buy from wholesale growers located in Washington and Oregon.

After this telephone survey was completed, Dr. Morton contacted

the wholesale nurseries in Washington and Oregon and asked

how 5 of the top 10 species of trees were grown. Their response

indicated that almost all were cloned. We can conclude, then,

that selective cloning to produce new trees is currently a common

practice for most nurseries across the United States.

The Morton and Gruszka study found that the genetic diversity was

greater in the older urban tree samples compared to that of the

nursery samples. The existing older urban trees are approximately

100 years old and were originally planted from seeds or seedlings,

representing decades of natural testing for resistance. Clearly,

existing older urban trees are a great resource for increasing

nursery diversity.

Some local groups, such as Tree Pittsburgh have begun growing

trees from seed, but a much larger effort will be required to change

the availability of such trees on a scale needed to supply the entire

country.

Lohr (2013) conduct a survey on plant diversity distributed to

wholesale nurseries in Washington State which showed that most

respondents were aware of the issues, but lacked an in-depth

understanding of them. The respondents reported that lack of

consumer demand was an issue. Those with more education

exhibited a deeper understanding of the risks from low diversity

among landscape plants. In summary, Lohr found that more

education is needed for people in the green industries on why

biodiversity and genetic diversity among landscape plants are

vital.

Morton has sought funding from several federal agencies for a

project that would share cuttings and seeds from tested genetically

diverse hardwoods with nurseries for the development of new and

hardier cultivars. Several large nursery have even written letters

of support for this research, but so far no funding has emerged.

A greater understanding of urban tree genetic diversity will allow

policy makers, city planning and environmental agencies, and the

nursery industry to make informed decisions and recommendations

to improve practices for maintaining a robust tree landscape for

the future.

References:

Bakys, R., Vasaitis, R., Barklund, O., Ihrmark, K., and Stenlid, J.

2009. Investigations concerning the role of Chalara fraxinea in

declining Fraxinus excelsior. Plant Pathol. 58(2):284–292.

Lohr. V.I. 2013. Diversity in Landscape Plantings: Broader

Understanding and More Teaching Needed. HortTechnology.

23:126-129

Morton, C.M. and Gruszka, P. 2008. AFLP assessment of genetic

variability in old vs. new london plane trees (Platanus × acerfolia)

J. Hort. Sci. Biotechnol.83(4):532–537.

Nowak, D.J. and D.T. Sydnor. 1992. Popularity of tree species and

cultivars in the United States. Gen. Tech. Rep. NE-166. Radnor,

PA: U.S. Department of Agriculture, Forest Service, Northeastern

Forest

Experiment Station. 44p.

Nowak, D.J., D.E. Crane and J.F. Dwyer. 2002. Compensatory

value of urban trees in the United States. Journal of Arboriculture

24:194-199.

Poland, T.M. and McCullough, D.G. 2006. Emerald ash borer:

Invasion of the urban forest and the threat to North America’s ash

resource. J. For.104(3):118–124.


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Citygreen Specifier Update 18

Engineering

Transcript of Citygreen Specifier Update 18