Laman street, in the heart of Newcastle, Australia, is known for its majestic avenue of fig and jacaranda trees that have grown to meet in the middle and create a stunning continuous canopy overhead. The trees are a host to a variety of native bird species; offer a cool, shady respite for residents and visitors atop the civic park stairs and a fittingly picture-perfect entrance to the Newcastle Art Gallery.
However, the story of the Laman Street fig trees is one of great controversy and while their impressive size has the appearance of them having been there, โforeverโ, they were planted only 10 years ago+.
2014
1 year growth
2018
5 year growth
PROJECT DETAILS
Location
Laman Street, Newcastle, New South Wales, Australia
Planting
2013
Council
City of Newcastle
Tree Species
Ficus microcarpa* and Jacaranda mimosifolia
Number of trees
10 ficus and two jacaranda
Challenge
Cohabitation of giant fig trees with modern infrastructure
*Ficus microcarpa is a tropical or subtropical tree native to China, Asia and Australia where itโs often planted for ornamental purposes and shading. In Australiaโs climate it grows to around 12m in height with a crown of equal spread.
2023
10 year growth
How fig trees divided a city
In 1931 well-intentioned city planners planted a series of Hills Weeping fig trees along Laman Street, to improve the leafiness of Newcastle civic centre, a town built around industry and mining, that had been left bereft of trees.
Fast forward several decades later to the early 2000โs, the figs had reached maturity and were now sharing space with asphalt roads, concrete pavement, kerbs, gutters and underground utilities. Concerns arose about the structural integrity of some of the trees and Newcastle City Council initiated plans to remove some of the trees citing safety concerns, as there were fears branches could fall and cause harm.
However, over the decades, the fig trees had created an iconic streetscape, often referred to as the townโs โgreen cathedralโ for its lush interlocking canopy in close proximity to a number of historic churches in Newcastle. So, when Council proposed to remove the figs it sparked significant opposition from local residents, environmental groups, and community activists. They argued for the preservation of the trees, to preserve their amenity, cultural, historical, and environmental importance.
In response, the Council commissioned an independent investigation into the condition of the trees, and the safety risk they posed. The trees were found to have too few large structural roots resulting in an almost linear root plate. Planted too close to the kerb, it acted as a pivot point under wind load adding extra stress on the root systems which were already vulnerable to extreme weather events. Ultimately, the study found the trees were highly unstable and that they posed a significant health and safety risk.
Why had the fig trees become unstable?
Their instability was due to the method in which they had been planted, coupled with a lack of knowledge of their growth patterns, compounded by the efects of encroaching modern infrastructure.
The trees were planted in standard root-ball tree pits and had outgrown the space available to them. Unable to sustain the large, healthy root systems needed to support their immense canopies, their planting had become an entombment. They were slowly dying, their limbs falling off as precursor to a ticking time-bomb. And that bomb went off in 2007 when the catastrophic Pasha Bulka storm hit Newcastle and four of the fig trees came crashing down.
Still, the controversy around removing the trees continued, leading to legal battles and extensive public debate until 2011, when, after years of dispute, 10 of the fig trees were felled in the interest of public safety.
The attachment the community had developed for the Laman Street fig trees motivated Council to explore the possibility of restoring new fig trees to the street but in way that would ensure peaceful cohabitation with the hardscape and underground infrastructure in the area.
After discussions with Citygreen, their expertise in growing healthy trees in challenging urban environments convinced Council the seemingly impossible, was in fact achievable.
โIt would have been much easier to replace the Hills Weeping fig trees with a variety of alternative species, better suited to urban environments, but that wouldhave marked a sad end of the trees planted almost a hundred years ago,โ explains Catherine Atkinson, Head of Projects, at Citygreen. โHowever we were delighted the City of Newcastle wanted to honour the legacy of the original figs and so we devised a solution for replacing them with a species as closely related to the original as possible.โ
THE
SOLUTION
โFig trees as a species are notorious for pavement heave which ruins the value of the infrastructure. But trees should be seen in quite the opposite way - as value adding.โ
Figs are naturally surface rooting and this is often a problem for urban environments where pavement heave is prevalent.
โFig trees as a species are notorious for pavement heave which ruins the value of the infrastructure. But trees should be seen in quite the opposite way - as value adding. If chosen and planted correctly, trees can thrive in urban areas offering a myriad of benefits such as improving air quality, regulating temperature through shading and cooling, encouraging biodiversity and improving physical and mental health,โ says Atkinson.
Citygreenโs structural soil vault system solved the Laman Street fig tree problem by providing all the space their roots needed to grow, but in a directed, managed way which avoids damage to infrastructure. The roots spread into the vaulted spaces allowing them to develop as stable and healthy root systems that are more resilient under climate stress.
The open matrix design of the Citygreen structural soil vaults were filled with a specified soil mix designed to deliver the highly aerated soil conditions figs prefer, providing optimal soil conditions for growth and to establish structural root systems.
โThe advanced soil vault systems deliver the conditions trees need to grow but, in an infrastructure and services friendly way. They are engineered to be load-bearing for pavements and protect the tree roots from pressure and compaction,โ continues Atkinson.
Permeable pavement was installed above the Citygreen solution to capture polluted stormwater run-off and harvest it for passive tree irrigation.
Results have exceed expectations
The City of Newcastle reaped the benefits of their investment after only a few years:
10-year growth projections were achieved in half that time
The new connected canopy cover now rivals the former 80-year-old trees, 10 years after planting
Surrounding infrastructure has been unaffected by the fast-growing root systems
The figs are a picture of health, restoring the amenity to the street for residents, visitors and local biodiversity
Three trees are hosts to an array of native birds and flying foxes
Ultimately the story of the Laman Street figs is about how these trees have been effectively managed and successfully re-introduced into the urban environment. Citygreen structural soil vaults addressed all of the problems experienced by the original Hills Weeping figs by supporting the above ground infrastructure, increasing soil volume, and reducing soil compaction to grow healthier climate resilient trees to be enjoyed by many generations to come.
โWith vast improvements in the public amenity, the Citygreen soil cell system has allowed the iconic Laman streetscape to live on, and we are pleased that it will be enjoyed by many generations to come.โ
In late 2018 Orange City Council engaged urban designers and architects sala4D to develop a plan for upgrading the CBD.
The last significant upgrade of the Orange CBD was undertaken in the 1990s. Since then, the way people and communities engage with the CBD and retail sectors has changed and evolved. The community asked for more places where they can gather and spend their time in attractive, fun spaces.
Project Goals
The concept plan for Lords Place South aims to make the city center more attractive and pedestrian friendly. The proposals include doubling the number of trees, introducing eight raised platforms for outdoor seating and dining, and creating nine new open space areas with trees, shade, and seating. Improved street lighting is planned to boost the nighttime economy.
With these tree plantings the number of car parking spaces in the area would be reduced by a third, from 67 to 44 to accommodate these changes
Artist Rendering of Lords Place, Orange
Project Challenges
Initially, there were 16 trees in Lords Place South; however, due to the new construction, and review of the current trees it was decided that 10 of them need to be removed. Similar to other trees in urban inner-city areas, the existing trees in Lords Place South encounter difficulties as their roots are largely covered by concrete and bitumen. Additionally, being planted in structural soil restricts the growth potential of their roots.
A huge community concern around the tree planting was the transition from a car-focused street to a pedestrian-focused street and the loss of car park space for businesses. Citygreen were able to mitigate the loss of car parking space by double planting of trees diagonally in line with the space of the carparks. These trees share the same treepit, an advantage of sharing the same treepit is that less soil volume is needed per tree overall as there is an overlap in soil use. At completion of the project there is now a total of 28 trees in Lords Place South.
The presence of existing underground utilities posed a significant risk to the project. However, with the modular design and large void spaces of the Stratavault system, the matrix can easily be built around utilities with minimal changes to the design; making Stratavault system the ideal solution.
Why Stratavault?
As part of the FutureCity program, new trees have been planted in Citygreens Stratavault matrix. These soil cells prevent the roots from spreading and causing damage to nearby infrastructure such as roads and underground utilities while providing the tree with optimal soil volume and compaction to ensure ideal growing conditions.
Another advantage of using Stratavault in busy urban areas like Lords Place is that the 100% recycled plastic modules are weight-bearing and designed to be trafficable, meaning cars can park safely alongside the trees without harming their roots. This approach helps minimize the loss of parking spaces, as the trees can be strategically positioned to maximize parking availability along the street. Additionally, the Stratavault Matrixes are connected to the cityโs stormwater channels, allowing the trees to thrive by intercepting water runoff that would normally enter the cityโs infrastructure and be taken out of the area.
There are a few main benefits when considering this approach:
Sustainable water utilization: The connected system allows for the harvesting and utilization of rainwater for irrigation purposes. This reduces reliance on municipal water sources and promotes water conservation.
Phytoremediation: Tree roots and soil microorganisms help remove pollutants, sediment, and nutrients from the water, improving its quality.
Enhanced urban cooling: As the trees in the Stratavault system receive ample water, they can provide better shade and cooling effects in urban environments. This helps mitigate the urban heat island effect and creates more comfortable outdoor spaces for residents and pedestrians.
Stormwater Management: Storage of water in high rain events helps to reduce demand on city infrastructure.
โItโs a great experience for our city as a whole to understand where the future of tree planting in heavily civil constructed areas can be going with cells in the ground.โ
Nigel Hobden,
Manager City Presentation
Orange City Council
Project Outcome
Orange City Council is taking a comprehensive approach to their green-blue urban initiatives, recognizing the valuable role of trees in enhancing the space through aesthetics, mitigating the urban heat island effect with shade and leaf transpiration, and optimizing stormwater management processes by integrating natural processes.
The success of Stratavault soil cells for trees in other locations in Orange, like Kite Street and McNamara Street, demonstrates Orange’s commitment to improving the CBD’s green urban spaces. This ongoing effort aims to attract more residents and workers to the city center while reducing reliance on cars for transportation.
We’re excited to keep an eye on how these trees grow and how the trees will help the CBD evolve the community experience.
Sustainable Carpark Solution Filtering Stormwater Run-off and Reducesย Environmental Impact on Urban Waterways
Key Facts
LOCATION: Wynnum Community Centre
105 Florence St, Wynnum, QLD, Australia
YEAR: November 2020
CLIENT: Brisbane City Council
CONSTRUCTION: JMac Constructions – Brisbane
About the Project
The project’s first stage was to transform the existing main building into a thriving and well-resourced community centre. Before the upgrade, the main building was utilised by various community groups.ย However, the off-street parking provided for these groups consisted of a temporary car park in old basketball courts. ย To address this issue, Brisbane City Council developed grand plans for the site to serve the community more appropriately.ย ย
Delivered and funded by Brisbane City Council on Turrbal/Yugara-Yugarapul/Jagera Country, the project has vastly improved vehicle and community movements along a busy corridor in the eastern suburb of Brisbane, in Queensland, Australia. Citygreen has been working towards completing the Wynnum Community Centre Project over the last couple of years, which has been a resounding success.
Project Goals
The first and second stage was to develop a shopping centre, which would offer the community access to Woolworths; this centre would also be home to a Council Library and other building spaces for smaller tenancies. ย The third stage included creating a small leisure park between the Shopping Centre and the Community Centre. To accommodate the changes and serve the community with more parking opportunities, stage 4 included building a permanent car park for the Community Centre.ย
To turn these plans into reality, Citygreen was called on to provide expertise on matters ranging from the design of stormwater drains, sprinkler systems, appropriate placement of sewer connections and the selected tree species. ย
Project Challenges
Ed Crouch, Project Manager at Brisbane City Council, said: “One of the conditions for development approval was to install a drainage cell system. The shared conundrum amongst the project team was how the asphalt surface directly beneath a car parking bay would be supported over the Citygreen Stratavault drainage soil cell system.”
The Citygreen Designstudio team engaged its engineers to design and certify this design component, which was promoted as the solution to this problem. Citygreen Designstudio also provided designs for the sprinkler system and reviewed the tree species that would best thrive in the carpark environment.
Another major challenge was achieving the falls for the stormwater. The most accessible stormwater main was on the other side of the site (Florence Street), which meant installing a stormwater line from the proposed permanent carpark down the Community Centre driveway. Also, a condition of the subdivision was a sewer connection had to be made to the surplus block to be sold off.
โCitygreen worked well with Councilโs structural and hydraulic consultants to suggest solutions to challenges. Citygreen called on in-house expertise to value-add to recommendations put forward by the project team. The relationship between all the parties was professional. All solutions to challenges encountered were based on a โbest for projectโ philosophy. โ – Ed Crouch, Project Manager at Brisbane City Council
Project Outcome
Landscape elements were prioritized for constructing the permanent car park, which was why Citygreenโs Stratavaultโข was chosen for the design. Citygreenโs Stratavaultโข is a highly engineered large soil cell installed easily under a car park to enable trees to accept, store and transmit water, nutrients, and energy while giving roots sufficient room to propagate.
The vaultโs structural matrix, manufactured from recycled polymers, is designed to provide an optimal growth zone for tree roots where high compressive strength is required and needed to withstand heavy traffic loads. Unlike the usual hardscapes delivered in an urban infrastructure project, the design team developed a car park that was considered the โend userโ. Citygreenโs Stratavaultโข allowed mature Eleocarpus Eumundii specimens to be planted, increasing the visual and physical amenities for pedestrians and cyclists, motorists and the local community.
In addition to managing stormwater, the system is used to harvest roof water for irrigation. By capturing rainwater from rooftops and directing it into the Stratavaults, the system can provide a reliable water source for tree irrigation, reducing the need for city water and providing a sustainable and cost-effective solution.
Water harvesting from rooftops is becoming increasingly popular in urban areas, as it can help reduce the demand for city water supplies and provide a sustainable water source for landscape irrigation. The Citygreen Stratavault system is an ideal solution for rooftop water harvesting. It can capture and retain water while providing a stable growing environment for trees and filtering pollutants from stormwater runoff, improving the quality of the water entering the city’s waterways. By integrating a water harvesting system with the Stratavaults, urban areas can reduce their water consumption and improve the health and longevity of their urban forests.
Ed Crouch, Project Manager, Civic & Building at Brisbane City Council, detailed that the key benefit of using the Stratavaultโข system
โThe growth rate of the trees and the water savings capacity and the fact that the technology allows for rapid root growth whilst confining the area of the growth so as not to cause damage to the car parkโs asphalt surfaceโ.
Today, the trees in the permanent car park show great signs of continued and sustained growth whilst helping filter pollutants from stormwater run-off. The team at Citygreen look forward to seeing how the trees thrive in years to come.
Hill East Building G is a mixed-use low-rise project in Washington D.C. that has been serving as temporary housing for displaced families for many years.
In a bid to put an end to homelessness, the Cityโs Mayor commissioned a redevelopment project on Hill East Building G. Part of the project involved transforming the area around the building, located on C Street Southeast, from a dull, grey area into a more vibrant green space by integrating numerous healthy trees.
The goal was to provide a more comfortable and sustainable environment for both residents and visitors.
BrightView Landscape Development worked together with urban greenery specialists, Citygreen, to facilitate the optimal growth of healthy trees along the sidewalk of Hill East Building G.ย Jeremy Clayton, Senior Project Manager, identified the Stratavaultโข system as the best solution to support the health of these trees within the paved pedestrian and vehicular environment.
Project Goals
One of the main objectives of the Hill East Building G redevelopment project was to showcase a thriving canopy of trees that would provide an aesthetic appeal, as well as shade, especially during the hotter months of summer.
โIt was our goal to provide sustainable solutions and advice around the planting of healthy trees in a new, trafficable concrete pavement. We also aimed to increase the number of street trees within the area,โ said Jeremy Clayton of BrightView Landscape Development.
The district administration also recognised that adding an urban canopy would turn the once-dull Hill East campus into a greener environment, giving families a more dignified place to stay until they could get back to a place they could call home.
โWe deemed this project to be a very complicated undertaking. The area had to be excavated very close to the building, and the spoils had to be removed from the site,โ Jeremy Clayton stated.
Fortunately, through our innovative solution, both teams at BrightView Landscape Development and Citygreen were able to overcome these challenges and deliver the transformational results that the City Government was seeking.
Project Methodology
BrightView Landscape Development had to find a system that could allow the growth of sustainable green canopies while also protecting the structural integrity of the surrounding streetscape.
After some thorough product reviews and consultation with the Citygreen team, it was determined that the Citygreen Stratavaultโข system was the most suitable solution to ensure that selected Exclamation London Planetrees would thrive in the harsh urban environment of the Hill East neighbourhood.
With its highly engineered large soil cell feature, designed to be easily installed under sidewalks, Stratavaultโข enables tree roots to grow, absorb and store essential nutrients. Its open matrix design also works to prevent sidewalks, roads and buildings from being damaged by root growth.
โWith Citygreenโs Stratavaultโข system, we were able to plant Exclamation London Planetrees along Hill Eastโs streetscape, as well as navigate multiple underground utilities and install strong concrete on top as part of the overall redevelopment project of the community.โ
Project Outcome
Citygreenโs Stratavaultโข system has been seeing positive results since the projectโs completion. The Hill East community, particularly Building G, is now decorated with healthy Exclamation London Planetrees that will soon provide vibrant visual aesthetics and cool shade relief for all residents and visitors.
Not only does this community provide a safe environment for displaced families, but the Hill East neighbourhood now offers a fresher, greener and cleaner space within the urbanised area.
โThe installation of Citygreenโs Stratavaultโข system progressed slightly faster than we estimated. On top of that, there was no rework necessary, and we were highly satisfied with the overall results,โ Jeremy Clayton said.
Thanks to Citygreenโs Stratavaultโข system, the Hill East community will soon have a thick canopy of healthy, lush trees that will deliver many environmental and health benefits, making the area more liveable and pleasing for its residents.
At Citygreen, our wide range of innovative urban landscape products like the Stratavaultโข system can transform communities just like yours.ย Speak to our team today to discuss how we can enhance your urban area to make it a greener and more thriving space, just like the Hill East neighbourhood in Washington D.C.
Maroochydore City Centre (MCC) on the Queenslandโs Sunshine Coast will be the first purpose-built city in the world designed specifically for driverless cars. A rare greenfield opportunity for developers SunCentral, the city will feature a range of innovative technology including:
Internet connectivity of unlimited speed enabled by a giant undersea cable
An automated underground, vacuum waste system
Automated light poles that respond to changes in natural light
Induction-charging roads to enable electric vehicles to stay powered constantly
Project Goals
Entrepreneur and technology advisor, Zach Johnson, said, โWe want to build something that doesnโt currently exist. In what must be almost a first in the modern era, we donโt have legacy infrastructure to contend with, weโre building from scratch. Weโve got this greenfield site and that gives us the opportunity to identify what sort of infrastructure is most beneficial to the use of autonomous vehicles โ but thatโs just one piece.โ
Another crucial piece to any successful urban centre is sustainable green space. Sunshine Coast Regional Council completed a successful tree pit trial with Citygreen in Caloundra five years ago and introduced SunCentral to this innovative technology. SunCentral and Citygreen connected, with Citygreen completing a thorough Cost Benefit Analysis for the MCC project.
Project Outcome
The challenge was that the initial design did not allow much room for trees in the sidewalk and road alignment. Trish Menzies, Senior Landscape Architect and Director at Vee Design, felt very strongly about the importance of incorporating green space and altered the design to include a continuous corridor vault where tree pits could go. With a dedicated space set aside, Citygreen completed thorough technical design and construction drawings for the Stratavault system, enabling 61 trees to successfully mesh in with the surrounding infrastructure. With just a few design revisions, SunCentral was happy with the design and constructability.
Construction is currently underway with positive feedback from the contractor, who says Citygreenโs detailed technical drawings have made the process quick and efficient. Theyโve also been surprised by how quickly the system is going in โ so much so that theyโre ahead of schedule. Stay tuned for a full report when this groundbreaking project is completed.
In 1917, Bulcock Street was established as the main street of sunny Caloundra on the Sunshine Coast. One hundred years later, competing against new urban centres, big-box malls and online retail, the rundown street was in decline. In a $12 million four-stage project, Sunshine Coast Council (SCC) transformed the tired main street into a vibrant and liveable community space through the Bulcock Street Revitalisation Project. This project is Australiaโs first smart city streetscape demonstration and testing facility, showcasing the latest smart city technologies.
Sian Crawford, the Landscape Architect at SCC, said, โWith the Sunshine Coast Councilโs Landscape Architects acting in many roles; the client, the project manager, design lead, and project delivery, our challenge was to take the community and organisation on a journey to re-imagine the high street experience through a holistic place-making framework. As Landscape Architects, we listened, learned and shaped the streetscape forms, layout, infrastructure, selected materials and plants species, and collaborated with engineers and artists, as key participants in this process of collective leadership.โ
10 Year Timelapse
The above timelapse shows the canopy difference of the same tree species planted at the same time. The only difference? Increased soil volume and quality.ย
A good analogy is imagine you're sitting down for dinner and the server brings you your plate and the plate is is 80% rocks. That's what trees planted in structural soil get; out of the available space, 80% is needed to keep the structural integrity of surrounding infrastructure and the tree is left over with a measly 20%; the growth and results of the tree are tied to the amount of resources available to it underground.
So, increasing the soil volume and nutrients available to the tree increases the growth rate of the tree. But that is tough to do in urban environments where infrastructure such as streets, roads, pavements, sewerage, power cables, etc take up a significant portion of underground space. This limitation will stunts the growth potential of urban trees, limiting the environmental, economic, and health benefits trees bring. However, employing innovative solutions like Stratavault will substantially enhance the available rooting area for trees by over 90%.
This revolutionary approach ensures that trees receive a more significant share of resources, promoting healthier and more vigorous growth while maintaining the structural integrity of urban infrastructure.
The difference in space available to the tree.
Download our Stratavault Tech Sheet to understand how we grow better trees in urban environments
Project Goals
Whilst the design responded to the communityโs desire for a green street with substantial tree planting and garden areas, the Sunshine City Council was also looking to build a greener and more sustainable town centre.ย Items that were taken into consideration during the design process included the ability to make the project sustainable in the long term with little to no human interaction.
As such, Citygreenโs Stratavault system, specialist soil mixes, and tree grow-on contracts were utilised in the building out of the project. What stands out about the systems that were put in place is their ability to ensure long-term sustainability for the project.
The capacity to deliver on the promise of long-term sustainability is Stratavaultโs ability to harvest rainwater. Meaning not only do the trees take in water during a wet period, but the system is also able to collect and store the water for dry periods.
Therefore, the 35 Elaeocarpus Obovatus that were installed between 2016 and 2018, utilising the Stratavault system can continue to grow and thrive in their environment due to the councilโs foresight in installing systems that look after the tree growth at the time of installation as well as into the future.
Project Outcome
โFeedback from the community has been overwhelmingly positive. In terms of the physical outcome, Bulcock Street is now a vibrantly-green, comfortable place to be. Momentum following the streetscape has resulted in a community embracing innovation and activation, with an increased sense of identity and self-determination. Eclectic in character, fun and colourful, the street has evolved into an โalternativeโ retail experience that appeals to all ages and is unique โCaloundraโ. Retail outcomes support this, with Caloundra experiencing an increase in the total spending during the 2017/18 financial year of 8% above the 2016/17 results (equating to $39.3 million in extra trade). An overwhelming success, the project was nominated for the 2020 Queensland AILA Landscape Architecture Awards.โ, said Sian Crawford.
Images below show the results from the Councilโs initial trial โ where the same species of trees were planted at the same time, in the same street โ with the Citygreen structural vault system (on the left), and with a rock-soil โstructural soilโ mix, on the right.
Tree in Stratacell yields 3x larger shade canopy than in conventional structural soil
About the trial
In February 2011, two different tree pits were planted at the same time with the same tree species (Chinese Elm) at the Ashfield Civic Centre in Sydney, Australia. The tree in the centre forecourt was planted using the Stratacellโข suspended pavement system while the two trees near the sidewalk were planted in structural soil (rock/soil matrix).
Over a year later, the canopy density of the tree planted using theย Stratacell system (suspended pavement โย right) is significantly thicker than the one on structural soil (rock/soil โ shown on left).
Key Facts
LOCATION: Ashfield Civic Centre in Sydney, Australia
PLANTED IN: Structural Soil (Feb 2011)
TREE SPECIES: Chinese Elm (Ulmus parvifolia)
PLANTING SIZE: 200l
AVG. CANOPY HEIGHT: 4m
AVG. CANOPY RADIUS: 2m
AVG TREE VALUE*: $419
LOCATION: Ashfield Civic Centre in Sydney, Australia
PLANTEDย IN: Soilvault Systemย (Feb 2011)
TREE SPECIES: Chinese Elm (Ulmus parvifolia)
PLANTING SIZE: 200l
AVG. CANOPY HEIGHT: 6m
AVG CANOPY RADIUS: 4m
AVG. TREE VALUE*: $9,425
Study
These early results from the Ashfield project are well supported by a fascinating study conducted by E. Thomas Smiley, Lisa Calfee, Bruce Fraedrich and Emma Smiley, comparing structural and non-compacted soils for trees surrounded by pavement.
In the 2006 study, Snowgoose cherry and Bosque lacebark elm were planted into five different soil treatment options under pavement, including compacted soil, gravel/soil mixture, Stalite, Stalite/soil mixture, and non-compacted soil.
After 14 months, the study found that there was more trunk diameter growth with the non-compacted treatment than the other treatments. There was also more twig growth, higher relative chlorophyll rating and more root growth compared to all the other systems.
The comparison showed that the foliar rating with the suspended pavement system was significantly better. Aside from this, โthe mean SPAD reading of foliar colour was also significantly higherโ as well as โthe root length at the rhizotronsโ.
The studyโs conclusions state that โsuspended pavement over non-compacted soils provided the greatest amount of tree growth and health and should be considered when designing urban planting sites for treesโ.
Citygreen Stratacell system is an engineered load-bearing matrix that supports pavement and traffic load while providing in excess of 90% uncompacted soil by volume.
Suspended pavement systems, especially those incorporating soil cell technology, are fast becoming the preferred choice for successful urban tree pit design.
Questions?
We are committed to providing forward-thinking and sustainable outcomes in the urban landscape industry. In order to develop well-planned green spaces across the globe and to help you achieve your vision, weโre now offering Discovery Workshops as an interactive online learning experience.
How Citygreenโs Stratacell โฏsystemย transformed Maitlandโs historic Levee Mall
The Levee Mall, formerly known as the historic Heritage Mall, was the most challenging project undertaken by Maitland City Council.
After almost 30 years of struggling to keep up with the modern suburban shopping centre scene, it was finally decided that the mall would undergo redevelopment in 2018. This plan involved integrating healthy trees into the street design while maintaining the historical value of the centre.
โThe street features a large number of significant heritage buildings from various eras throughout the 19thย and 20thย centuries. However, trees were strategically located in front of buildings with a lower heritage value to form an aesthetic balance,โ Aaron Cook, Operations Manager Projects & Contracts of Maitland City Council, stated.
Citygreenโs Stratacell โข system was identified by Adrian McGregor, the Senior Landscape Architect and Founding Principal of McGregor Coxall, as the best solution to support the health of these trees within the paved pedestrian and vehicular environment. This approach was taken to enhance the overall structure of the pedestrian zone and shopping mall while adding greenery and natural scenery.
The Citygreen team joined this project to contribute to its overall success.
Levee Mall: The Redevelopment Project goals
Citygreenโs main goal for this project was to maximise the value of the Maitland site to transform it into a highly desirable destination for both shopping and socialising.
The other objectives were to:
provide sustainable solutions and advice around the planting of healthy trees in a new, trafficable stone-paved street
increase the number of street trees within the refurbished mall, and
assist with complex pavement design considerations and Water Sensitive Urban Design (WSUD) concepts.
Adrian McGregor added, โOur master plan was to utilise urbanism strategies to revive the place. Supported by the local produce and wine economy, we aimed to reposition Central Maitland as a leisure-based retail activity centre for all the local communities. We were commissioned to implement our regeneration plan to convert the former outdoor pedestrian mall into a new high street, a WiFi connected shared zone and active public realm. It was a very exciting project.โ
Project challenges
The Maitland City Council determined that trees did not grow well in compacted soils like structural soil, posing a problem for the redevelopment plan from the very start.
Aaron said, โClay pavers were failing, tree planting was unsuccessful, and the street was cluttered with various physical elements that had been introduced throughout the former life of the mall.โ
He also added,โPrior to the refurbishment, existing trees were suffering from compacted soils in a fully paved environment.โ
Fortunately, the Citygreen team had a plan to overcome this challenge and deliver the results that the Council were looking for.
Project methodology
Considering the difficulties previous street trees were having at the site, it was important to find a system that could produce sustainable green canopies, encourage healthy growth and protect local structures.
After reviewing various products and consulting with the Citygreen team, the Citygreen Stratacellโข soil system was chosen as the most suitable solution to ensure the selected indigenous Tuckeroo trees (Cupaniopsis anacardiodies) thrived.
Aside from having a proven track record of success in similar projects, Stratacellโข was chosen for several additional reasons such as:
Stratacellโข modules are crush tested during manufacturing and are 3x stronger than any other product, which is critical in this case as trees would be growing in a shared space with vehicular overrun.
Stratacellโข modules have the highest structural integrity of any large soil cell. They connect seamlessly to form a matrix, ensuring loads are distributed evenly.
This system is sustainably made using 100% recycled polypropylene, so they are an environmentally-friendly choice.
Despite their incredible strength, Stratacellโข modules contain no steel components, meaning there is nothing that can rust or corrode – which was a critical factor for the longevity of The Levee project.
Project outcome
Citygreenโs Stratacellโข system has seen positive outcomes in contrast to the previous tree planting efforts on the site in the past. Besides supporting healthy street tree growth, Citygreenโs Stratacellโข modules have helped to preserve the centreโs historical value by enhancing Levee Mallโs rich history and visual aesthetics.
It has been a few years since the projectโs completion, and the Tuckeroo trees are thriving, providing shade, colour and charm.
โThe street trees are healthy and growing at an appropriate rate,โGlen Thorley, the Coordinator of Tree and Recreation Works of Maitland City Council stated. โIt has been a great success.โ
These indigenous tree species have also reflected the character of the region, provided a good habitat for local fauna and offered shade and protection across all of the public areas. The project also took heritage significance into account by showcasing the aesthetics that contribute to the streetโs overall culture.
At Citygreen, our wide range of innovative urban landscape products like the Stratacellโข systemย canย transform yourย communities to be greener, healthier and more sustainable too.
Speak to us today so our team can discuss how we can enhance your urban space into a greener and more thriving place, just like the Levee Mall in Maitland.
โGreat customer service, quick response times and a very in depth QA system with constant support.โ
- Laura Wiesenekker, Project Engineer, Densford Civil -
โCitygreen is aย very professionalย business, and I found everything was great in terms of deliveries, product supply and information. It was all forthcoming and helped us to complete the project.โ
- Keith Burns, Architect/Designer, Keith Burns Architect -
โCitygreen offered training and invaluable technical assistance during the works.โ
- James Callan, Estimating Manager, Complex Co Pty Ltd -
โOur experience, in working with a Citygreen Design Studio was second to none. We found responses from the design studio to be very timely, and technically thorough. We went backwards and forwards a number of times, looking at different iterations of the design and, nothing was too much trouble to examine and explore different possibilities. I would highly recommend the Citygreen Design Studio to any future client considering using your services.โ
- Sandra Smith, Principal Landscape Architect, City Of Monash -
โWe are big on compliance on all projects, and the fact that their SmartCertify cloud platform covers all bases, and supports their 20 year warranties, is critical โ especially that these pits are being installed under roadways and footpaths.โ
- Johny Purkaystha, Civil Program Engineer, Central Coast Council -
"I reviewed all the previous projects that we have installed in the past couple years using your product and I can happily report back that we have 0% mortality in the soil cells, which is incredible!"
- Brendan Wilton, CEO, Trim Landscaping, Bedford, Canada -
The trees were planted in standard root-ball tree pits and had outgrown the space available to them. Unable to sustain the large, healthy root systems needed to support their immense canopies, their planting had become an entombment. They were slowly dying, their limbs falling off as precursor to a ticking time-bomb. And that bomb went off in 2007 when the catastrophic Pasha Bulka storm hit Newcastle and four of the fig trees came crashing down.
