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Tree renewal at a prestigious Victorian School


Tree renewal at a prestigious Victorian School keeps future bright for students
By Kristyn Levis


When one of the schools in Victoria needed to revamp its facilities, the architects had to find a robust soil cell that would suit the limited space of the project without compromising soil volumes for the trees.

The Citygreen modular Stratacell system is an all around product that ticked all of the requirements for this campus in Keilor East, Victoria.

The Penleigh and Essendon Grammar School project required the redevelopment of the Boys Middle School, which included a new facility and refurbishment to the existing classroom building.

Penleigh and Essendon Grammar is a Uniting Church School for boys and girls with campuses in Essendon, Moonee Ponds and Keilor East in Victoria. The school is the union of Penleigh Presbyterian Ladies’ College and Essendon Grammar School.

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Joshua Chia, Senior Landscape Architect from ACLA, was part of the design team for the project, including architects from McBride Charles Ryan. The design stage started in mid 2011 and construction began early 2012. The whole thing was completed by July 2013 with a landscape budget of around $400,000.

“The landscape scope included the main entry and courtyard design, providing active and passive recreational opportunities for students while facilitating access between the two buildings,” Chia said.

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He added that a double row of avenue of trees were proposed centrally within the courtyard to provide shade and cooling from the surrounding hardscape, while strengthening the orthogonal lines of the buildings, designed to reflect the principles of the Roman Forum.

“A super advanced feature tree (Brachychiton acerifolius) was proposed for the main entry as a focal point,” Chia said.

Because of the restricted space of the courtyard and its intended use in facilitating access and providing areas for ball games, Chia said the design had to be robust.

“Existing trees planted in small tree pits within the existing courtyard had damaged the pavement and become a safety issue. To allow for trees to be installed within pavement and become a major asset for the space, we felt the Stratacell system was the best solution in providing uncompacted soil around the trees while structurally supporting the pavement above,” Chia said.

Aside from the Stratacell system, the project also used Citygreen’s RootRain Precinct.


The RootRain Precinct and ArborVent kits are for central urban locations requiring a permanent irrigation/aeration solution and heavy-duty cast-iron inlet. The series have been specially designed to interlock with Citygreen’s range of integrated tree grilles. This provides a tamper resistant system that will also prevent the inlet sinking as a result of any soil settlement around the tree.

“Based on past failures of trees in urban environments and damage to surrounding pavements, it’s proof that adequate soil volumes are very important. While we were unable to achieve the absolute ideal target soil volume on this project due to budget restraints, we saw any significant improvements to the growing conditions as being beneficial,” Chia said.

The biggest issue they faced was designing within such a tight budget. Although they had to substitute materials and treatments, Chia said they were “adamant that the Stratacell system had to go in”.

It’s only been a year since the trees were planted, but Chia said the trees are establishing well.

“We are hopeful that this will continue to be the case for years to come. There is no doubt the Stratacell system provides major benefits over other more traditional systems” he said.


Based on the feedback from contractors, Chia said they knew that the system was very simple to install. They had very little issues with the installation and a Citygreen representative was present to help guide the contractors through the installation process.

Chia said they have since incorporated the Stratacell system into a number of subsequent projects.

“The trees are looking great. However, having only been a year, we are sure we will see the benefits in the coming years,” he said.

Growing Trees Smarter in Marrickville


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Trees usually come second to footpaths, roads, kerbs and gutters – but Marrickville Council is determined to turn this thinking around.

So when a footpath was being upgraded in Cavendish Street Stanmore, Council’s ‘whole of street’ approach presented an opportunity to remove and replace three very large Ficus hillii with an in-road tree planting of three super-advanced Waterhousea floribunda (Weeping Lilly Pilly).

This new approach by Council means that damage from tree roots to nearby properties and structures will be prevented. It’s all part of a new initiative called Connecting Marrickville.

Connecting Marrickville puts people and the places they live in at the centre of all infrastructure planning. It aims to make streetscapes better now and into the future. How? By integrating all elements that make up a liveable sustainable community.

Gwilym Griffiths, Council’s Coordinator Tree Management, was part of the multi-disciplinary team who worked on the design, construction and communication. He said the objectives were to demonstrate a new way of managing the conflicts between trees and infrastructure; plan for large trees in tight urban spaces so that there is significantly less need for pruning and patching of damaged infrastructure, and to integrate tree works and footpath replacements in one project.

The project site construction started early May 2014 and finished in June 2014.


“There is more and more pressure on street trees,” he said.

“In many towns and cities, development means that people and trees are brought into increasingly closer contact. Space for large trees to establish to full maturity is limited. It’s all exacerbated by poor or disturbed soil conditions in built up areas, and conflicts with underground and aboveground services,” Griffiths said.

“And there’s this idea that large trees cause damage or can be dangerous. They might drop branches, or block sunlight, or damage infrastructure,” he added.

Connecting Marrickville will manage these issues by planning for the needs of the trees (providing them with the soil and space for long term growth) instead of just planting trees in the spaces ‘left over’ after development.

In a council video about the project, residents commented on the bumpy footpaths, saying while they wanted more greenery, they didn’t want tree roots ripping up the path.

The three large trees roots were also growing into people houses, with one even growing into someone’s bath.

Council removed those trees, fixed the footpath, and planted the new trees in-road using the Citygreen Stratacell system.

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“We chose this system because it provided the best soil volume per dollar when compared with other structural soil systems such as aggregate soil and pier and beam vaulted systems,” Griffiths said.

“Adequate soil volumes are crucial for sustainable tree growth. Providing soil volumes upfront for trees provide better trees and less impact on infrastructure,” he said.

The system, Griffiths said, is very easy to install and doesn’t require specialist skills. They had very minor difficulties fitting cells around numerous services, and during the initial design phase, in getting the specification correct.

“We also received a lot of rain during construction, which required pumping out and modification of the gutter to reduce the amount of water flowing into the pits,” he said.


Ryan Hawken, Council’s urban water engineer, said although the upfront cost was higher than previous projects, there are long term benefits such as much less damage to footpaths and houses.

Council will monitor costs over time in order to continuously improve performance and management of streets and trees. Since the project was completed, Griffiths said the biggest issue has been to maintain adequate water to the trees.

“Initial water budget estimates were quite low and since completion have been increased to accommodate actual site requirements,” he said.

The project included planting of biodiverse species of grass and ground cover and stormwater management by adding permeable paving over the tree pit to capture surface water. “And the Stratacell fits well with this,” Griffiths said.


“Today, the trees look good and are stable. We would definitely use a similar system again,” he said.

The project is being used as a case study for Council’s Connecting Marrickville initiative. This project delivers on a range of Council strategies and provides Council with a great example of what can be achieved with the right thinking.

Marrickville Video

For a full project view, see the multifunctional infrastructure case study video created by the Marrickville Council. It includes commentary from the projects landscape architect Yvonne Vale, Gwilym Griffiths, Council’s Coordinator Tree Management, Water Engineer Ryan Hawken, and Cavendish Street residents.

Trees with Stratacell Result in Vibrant Transformation


Trees with Stratacell Result in Vibrant Transformation
By Kristyn M. Levis


The Vaughan Street Redevelopment, dubbed Vaughan Central, has created a more pedestrian friendly atmosphere in Greater Shepparton, Victoria.

The redevelopment of the Vaughan Street precinct, which started in July 2013 and finished in November 2013, involved three major stages. It enhances pedestrian access and central urban space in a street that connects the Shepparton railway regional transport hub, the suburban bus network and the taxi services with the Shepparton CBD.

The first stage of the urban renewal project involved significant streetscape and construction works to the commercial area, road and parking areas. The areas included the upgrade of the streetscape of Vaughan Street between Corio and Maude Streets, raised pedestrian crossings and footpath along the southern side of Vaughan Street, removal of existing angled street parking and replaced with parallel parking and a better flow of traffic, a new taxi rank, CCTV, and the removal of street trees. It was worth $3 million with contributions from the Regional Development Victoria, Lascorp and the Greater Shepparton City Council.

Vaughan St Shepp 20130802 (8)_1

“The removal of street trees will result in visible vegetation loss. However, the removal of unsuitable trees and the placement of an avenue of trees more suitable to the environment will enhance the streetscape in time,” the website said.

The council site said the new Zelkova trees are very suitable for the commercial business environment. The design of the Citygreen® modular Stratacell system® “allows better watering and aeration for the root system as well as better drainage”.

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“This encourages the establishment of roots to grow beneath the surface, reducing the disruption to paving. The roots will grow deeper in the moist soil to encourage drought tolerance,” the site said.

The site said the council included the Stratacell system in the design to “encourage the tree roots to spread through the un-compacted soil without impacting on the road and infrastructure.

Heath Chasemore, team leader for Parks at the Greater Shepparton City Council, provided advice to the project manager on the landscape design and ongoing maintenance issues.

The Greater Shepparton City Council has used the Citygreen Stratacell system on a number of locations before the Vaughan Street development, with the first installation completed three years ago.

Vaughan St Shepp 20130802 (2)

“Soil volumes are very important to the ongoing sustainability of tree planting. A benefit of this system is the ability to increase soil capacity by the addition of more modules,” Chasemore said.

The only minor issue they faced was training contractors to install the system. But this was easily overcome by the presence of Arborgreen staff spending time on site with contractors, explaining how to install the product.

“Once staff and contractor were shown the correct installation, the product was very easy to install,” he said.

Their biggest issue was with the location of services into the growing space during the initial design phase but it was easily solved.

“Because we have integrated this product into the design stage there was a good fit with other landscape elements,” Chasemore said.

Liesl Malan from Liesl Malan Landscape Architects said the city of Shepparton is “a tough environment for trees”.

“Winter is cold and the frosts are heavy. Summer is hot and extremely dry and the selection of commercially available stock suited to the climate is much more limited than the range available to our colleagues in city areas.

“Once we all accepted the sad reality that the existing trees were in such poor condition that we would be unable to retain them, we spent a great deal of time working with Greater Shepparton City Council to find the right tree combination for the new streetscape,” she said.

Malan added that there was anxiety over the removal of the existing trees and the challenges of successfully establishing new street trees.

“We decided to introduce the idea of using tree cells during the concept phase of the project and fought hard to retain them during the inevitable budget reviews,” she said.

Some of the challenges faced by the team include construction timing and stock availability, and the size of the new trees as they were not as large as specified. However, Malan said they’re “confident that the tree cells will provide a good growing environment” and the trees will be able to “provide shade for the streetscape in a relatively short period of time”.


The redevelopment of Vaughan Street was a “tremendous opportunity to reinforce the link between the railway station and the mall”.

“We were able to fix the uncomfortable camber of the road and the narrow (in some cases non-existent) footpath provision. We created generous, consistent footpath areas, pedestrian crossings at a consistent level to the footpaths and a series of welcoming seating areas. Unique furniture pieces were designed drawing on Shepparton’s history, industry and natural environment,” Malan said.

These features for the project were key to creating a strong identity, specific to the Riverina. The furniture was made locally and can be easily replaced using local skills and resources, if necessary.

“In removing the existing trees, we were very conscious of the significant investment the city had made in planting the original Plane trees. They were the best option available at the time and they have provided a shaded, welcoming streetscape ever since. They have also withstood the installation of so many new services as the city has grown and modernised,” Malan said.


“We hope that incorporating tree cells in the new streetscape will, in time, be seen as the best way to balance the needs of the trees and the necessary infrastructure for the rest of this century,” she added.

As of today, Chasemore said the “trees are looking good in this location and at other locations where this product is installed”. They are planning to use the system again in the next streetscape development.

Trees Thrive in Concrete Pavement – Denmark


Trees Thrive in Concrete Pavement


The emphasis placed on the recreational areas adjacent to Novo Nordisk’s new headquarters in Bagsvaerd is clear.

There are two new notable buildings that form the framework for the new headquarters, and the buildings have space for 1,100 employees. But it is the associated park with an area of nearly 31,000 m2 – the same as about four football fields – that attracts attention.

The park area is designed to replicate the natural Danish forests and landscapes. It is a beautiful interpretation of the Danish countryside and consists of various biotypes including 50 different tree species. The park area provides natural, informal and pleasant surroundings, in which the employees can walk to meetings, enjoy the views and relax. The park area is also open to the general public and one can follow the winding white paths that meander through the various habitats.


The tree species have been carefully chosen to provide and attractive palate of colour throughout the year. Pines and blue spruce with their evergreen needles provide a blue-green backdrop all year round. In the winter, this backdrop is supplemented by the white birch stems and the red and orange stems of the cherry trees. In spiring, these cherry trees explode in blossom, followed by the new, fresh green leaves of the beech trees. The multiple stemmed and wild trees look after themselves ensuring natural development of the biotypes is achieved with minimum levels of maintenance required.

SLA were the landscape architects responsible for the design of the park area.

  • To create a landscaped area with as much great diversity as seen in the natural Danish countryside requires, of course, diverse soil types. The soil types are carefully crafted to meet the requirements of the individual habitats in order to ensure optimal growth conditions, explains Morten Leicht Jeppesen from SLA

But it is not only the soils that have been carefully crafted to match the biotypes – as not all the trees have been planted in the biotypes. Outside the main entrance to the building the trees have been planted in the midst of the slate paving, adjacent to the entrance road and above the underground carpark! Here, StrataCells have been used as a structural soil cell system to ensure the integrity of the surrounding paved areas.


  • “The Stratacells create an underground soil island in the concrete where the tree roots can spread even though they aren’t planted in a natural environment, this ensures a natural growth”, says Kim Bøge of Skælskør Anlægsgartnere, the landscaping company that has been responsible for the planting.

The StrataCells provide a solid, stable surface for the slate paving to be laid over.


  • Without the Stratacells there would be a risk of the surrounding paving sinking in the soft soils when subjected to traffic loads, says Kim Bøge. The cells are there to provide support to the coating paving. It They also withstands heavy traffic loadings and adds provide good soil volume for the trees.
  • “Another feature is the relatively low weight of the Stratacell system, a very important feature when you consider that these trees are planted on the roof of an underground carpark. If the treepits are too heavy, you risk the roof collapsing”, says Morten Leicht Jeppesen.


  • Stratacell modules are made of 100 percent post-industrial waste.
  • The modules can be used anywhere where trees are being planted in areas with one or other coating.
  • The opening in the nesting is large enough to allow for pipe penetrations, such as drains, cables and aeration systems.
  • More than 94 percent of the total volume is available for root growth.
  • Units snap together quickly and easily, resulting in a significantly reduced time spent on the site.

For more information contact:
Mark Walton, Project Manager at Milford, www.milford.dk, tel. 44 97 10 99
Milford is a supplier of systems and products for the improvement of urban space and landscape in Scandinavia.

Stratacells Help Transplant Mature Trees in Forrest Place Australia


Stratacells help transplant mature trees in Forrest Place Australia
By Kristyn Levis


The Citygreen modular Stratacell system has provided a much needed solution to the transplanting of trees for the Forrest Place project in Perth Western Australia.

The project’s aim was to link Forrest Place with the Perth Station Forecourt in order to create a “grand space” for the city’s primary urban area within the CBD.

Andrew Baranowski, director of Plan E, collaborated with Woodhead Architects and the City of Perth in the planning and design of the Forrest Place and Perth Station Forecourt.


Baranowski said the space was to be “contemporary but evocative of a traditional formal city square, cohesive in design and highly flexible to function with both a day and night culture”.

Plan E started designing the project in 2006. Construction was completed in 2013 with an overall budget of approximately $21 million. The project team was fully multidisciplinary and Plan E worked successfully with the architect, the construction engineers and electrical, structural, civil, hydraulic and irrigation consultants.

“The design establishes a seamless visual and physical connection between Forrest Place and the station forecourt by the removal of the pedestrian bridge and the stairs to Wellington Street, and extending consistent treatments across Wellington Street into the station forecourt,” Baranowski said.

He added that in order to improve the flexibility of Forrest Place as a venue for major performances and events, the stage area was repositioned and a new overhead canopy was provided.

“The space incorporates new seating areas, transplant trees, an interactive water feature and a controversial sculpture, combining to create a more dynamic and interesting space,” he said.

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One particular issue with the project was the transplanting of trees in the area. Baranowski said nine mature Chinese Elms from the Perth Station Forecourt on Roe Street had to be relocated into the space, “which presented logistical problems in terms of transport and access, as well as soil depth and space (due to construction over car park slab)”. They had limited soil depths in which to plant the proposed mature Chinese Elms on the site.

Using Stratacells as the structural soil cell easily solved this issue. Baranowski said the Stratacells “offered the perfect system to ensure an adequate volume of soils to sustain the trees into the future”.

Forrest Pl First Install (11)


Forrest Pl First Install (10)

He said that providing adequate soil volumes to tree wells is the “single most important factor in the success of tree planting in urban spaces such as Forrest Place, particularly where the trees are semi-mature transplants and planted over a car park structure with limited soil depths ranging from 0.70 to 1.2 metres”.

That is why they wanted to ensure that the contractors installed the Stratacells correctly in the initial stage of the project. This was made easy by the site presence of a Citygreen representative during the installation process. Once the contractors knew how to install the Stratacells, every thing else fell into place. The system worked very well for the intended design of the project.

“The system is better due to its flexibility, modular design and speed of installation, in comparison to other systems we have used. The system is comparable in materials cost. However due its speed of installation, we believe that it is more cost effective overall,” he added.

He said that the trickiest issue they faced was getting the drainage to the tree wells working correctly. It resulted in a number of the trees failing. During replacement of the trees, further drainage was installed which resolved the problem.


Other challenges that the project faced include the lighting design, water delivery and the selection of robust materials. Lighting is a significant feature of the Forrest Place project. It has been designed so that “there is a high degree of control to act as theatre lighting for events”. The lighting will also change with the seasons, with a cooler light in summer and warmer lighting in winter.

Water harvesting design was also included in the project where all rainwater from paving is collected in a large underground tank and then used for irrigation.

The project also required the selection of “durable and robust materials and construction methods, including the granite paving (utilizing WA granite) and the precast concrete walls and seats”.

The Stratacell system fits well with what the project needed given the module’s extremely high compressive strength. It can sustain the weight of an ASV PT-50 multi terrain loader and has a 550kPA vertical load. Aside from having a very high strength capacity, the Stratacell modules are also recyclable and are manufactured from 100 per cent recycled polymer. As there are no steel components, the modules are corrosion free.

Plan E was quite happy with the system that it has been specified in other projects, including the Cambridge Streetscape, Perth City Link, and more.

“After the initial problem with drainage, and establishment of proper monitoring procedures, the trees are performing very well,” Baranowski said.

Frankston Creates Safer Walking Lanes


Frankston Creates Safer Walking Lanes
By Kristyn Levis


The City of Frankston in Victoria wanted to encourage its residents to walk more by providing a safe and aesthetically pleasing environment.

This goal was achieved through the Principal Pedestrian Network Demonstration (PPND), which was partially funded by the Department of Transport Planning and Local Infrastructure, and with the help of the CityGreen modular StrataCell system. Its aim is to promote walking as a means of transport and “providing suitable improved public amenity”.

The design phase started early 2013, with construction starting in February 2014 and completed in April 2014. The total project budget was $1,132,000. The Frankston City Council and Aspect Studios, in consultation with the local community and traders, developed the plan to “promote walking between key destinations and enhance exploration of Frankston’s central laneways”.

The route includes north – south pedestrian access to retail outlets including Bayside Shopping Centre, local traders and the Frankston Transit Interchange.

The design included new lighting, trees, new furniture and art components following the Crime Prevention Through Environmental Design principles to enhance safety and avoid graffiti and neighbourhood waste.

Marti Fooks was the Frankston City Council project manager involved in the design phase up to the completion of the construction. She now works with Aspect Studios.

As a registered landscape architect, Fooks supported the use of Stratacells “to provide the optimum conditions for the trees to establish”.

“This was the first application of Stratacells in Frankston, demonstrating Frankton’s commitment to healthy trees in urban environments and hopefully paving a way for future projects,” she said.


Fooks said the project “employed a range of innovative spatial design outcomes, suited to the site context that would make walking a more desirable experience”.

“Trees were a key aspect to the proposal in Park Lane as they completed a continuous avenue of green foliage and provided a screen to the unsightly car park behind,” she added.

Adrian Cadenazzi, project manager from 2Construct – the principal contractor engaged on the project, said they were only involved when the final design was in place.

“It was evident from speaking with the client and architect that to a large extent, the design was based around the Stratacell system, which was one of the main selling points to the council members during the planning stage,” he said.


Fooks mentioned that there was some initial resistance to the use of Stratacells because of the additional cost to the project. But advocating for their use “was made easy with a cost benefit analysis as well as showing photos of the existing poor soil conditions”.

She said that the Frankston City Centre is in a floodplain and because of this, water logging can constrain the establishment of trees.

“Water logging will not only cause unhealthy trees, but tree failure is also very costly. Park Lane was no exception with heavily compacted clays reducing drainage and soil media to promote tree establishment,” Fooks said. “By using Stratacells we were able to provide the three new Platanus Acerfolia with more than 100m3 of growing media rather than only 8m3 per tree.”


Cadenazzi said that the soil volume required for tree pits very much depends on the species of tree specified. Fooks agrees saying that soil volumes and qualities are absolutely crucial to the success of plants and trees in urban environments.

“In this instance, Plane trees were required which grow quickly and to a large size so soil volume needed to be extensive to support the growth. The system did provide enough volume while maintaining trafficable pavement above,” Cadenazzi said.

Like other similar projects, underground services were discovered during construction. They were in a slightly different alignment compared to the service proving information. Cadenazzi said the existing electrical services required “a slight reduction in the overall size of the system to avoid lengthy delays with relocating live power”.

“Of the different options such as bridging Stratacells, it was determined that to keep on track with the program the number of cells was reduced to four rows rather than five,” Fooks said.

“In consultation with Citygreen and Aspect studios, it was concluded that the reduction would not cause significant issues with supporting the growth of the trees,” Cadenazzi said.

Aside from underground services, Cadenazzi said the installation of the guy wires prior to placing the trees was “a tricky process requiring a combination of finesse and brute force”.

“Also, the trees themselves being 400L specimens, are cumbersome to handle and, having to work with limited room once the Stratacell system was installed, can make it a fiddly process,” he said.

However, installing the Stratacell system was itself a straightforward process. “We relied on the web video tutorials provided on the Citygreen website for guidance and these were extremely useful in having the entire process broken down step by step,” Cadenazzi said.

Fooks seconded this saying that the installation was “incredibly simple” and that the cells simply locked into place ready to be filled with soil media.


With their experience on the Frankston project, Cadenazzi said that although they don’t get involved during the specifying and design stage, they have no hesitation in endorsing the Stratacell system.

“As the trees are deciduous and were planted in late autumn, they are currently dormant so it is too early to comment on the success. From a structural perspective, there have been no issues with pavement failure that we are aware of,” Cadenazzi said.

As an associate at Aspect Studios, Fooks said she would definitely consider the use of Stratacells where the project calls for it.

“Where a pedestrian or vehicle grade surface is required adjacent to trees, Stratacells are the best solution to provide soil underneath while holding up the finished surface,” Fooks said.


In August 2013, Frankston City Mayor Sandra Mayer said she was very excited about the improvement given that the route down Park Lane and through the car park was not safe.

“These improvement works will ensure these pedestrian walkways are safe and easier to navigate. The urban art work and lighting elements will also brighten up the city at night time,” Mayor Mayer said.