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Amazon leverages cutting-edge Stratacell solution in new Seattle headquarters


Amazon leverages cutting-edge Stratacell solution in new Seattle headquarters
by Sally Cameron

E-commerce and cloud computing company, Amazon, has leveraged Citygreen’s cutting-edge Stratacell™ system in its new multi-million office headquarters in South Lake Union, Seattle. Purpose-built to accommodate 20,000 employees, the new headquarters consists of multiple buildings surrounded by mingling areas and plazas.

One plaza, located between two buildings on 6th Avenue, has been constructed above a parking structure, and is home to several feature trees (Cercidiphyllum japonicum and Magnolia laevifolia) requiring large planting areas.


Engineering plans allowed enough soil volume beneath the plaza to house the trees, but a significant challenge emerged – how to provide sufficient structural support to cope with the weight of heavy vehicles such as a boom lift, to be used for maintenance. Soil cells were identified as an ideal solution, however many products were rejected because they lacked the structural strength required.


Citygreen’s 60-series Stratacell system fulfilled the strength requirements, and Citygreen worked directly with the consulting landscape architect – Site Workshop of Seattle – to design the structural elements of the plaza. This consists of 500 StrataCells, supported by a concrete slab, a drain-mat, and another slab above. Citygreen provided plan views of the installation to calculate the quantity of cells required, and to show how the slab would be supported. Construction was completed by Pacific Earthworks.

Site Workshop, along with the project architect, are very happy with the solution, making particular note of how quickly the cells went together and how easy it was to thread the drip irrigation through the structure. Time will tell how the rigidity of the plaza structure performs, but all signs point towards to successful outcome, with beautiful trees for Amazon employees to enjoy.

Stratacell system resolves pavement lift on Chapel Street

Chapel St_2

Stratacell system resolves pavement lift on Chapel Street
by Sally Cameron


Chapel Street, South Yarra, is one of Australia’s most vibrant and successful commercial, residential, and cultural areas. Featuring premium Melbourne restaurants, designer shopping, and the iconic Jam Factory Cinema, Chapel Street has firmly cemented its place as an international tourist destination. 

Simon McKenzie-McHarg, Landscape Architect at the City of Stonnington, oversaw a streetscape upgrade which commenced in early 2014. “Chapel Street gets a very large volume of pedestrian traffic, and we were becoming increasingly concerned about the damaged pavement, which had lifted noticeably around the existing street trees. Not only did this look unsightly, it was also posing a significant trip hazard and was having a negative impact on the health of the trees.”

“We decided to remove the existing trees, and then re-plant the main street, but we recognised we needed a better long-term solution for the new trees to ensure we avoided the same problems with pavement lift.”

“Citygreen’s Stratacell™ soil cells were identified as the ideal solution, providing plenty of unrestricted root space for the new trees to thrive without damaging the surrounding pavement. We planted the new trees – nine Cimmaron Ash – within a continuous strip of Stratacells, repaved the footpath, and then installed custom tree grates and tree guards to ensure the longevity of the trees.”

Chapel St_5   Chapel St_6

“Citygreen were great to work with, and really accommodating when we had some design and material changes mid-project. They came down to site several times to offer advice to the contractor around the installation process, which was really useful given the system was new to the contractor.”

“Two years down the track, the streetscape looks fantastic. None of the trees have died, and they’re all growing really well – particularly given the highly-urbanized environment. The tree guards have also done their job, protecting the trees from vandalism. It terms of the surrounding pavement, it’s still early days, but there’s been no pavement lift as yet which is very promising.”

“Overall, I’d definitely recommend Citygreen as an approachable team of professionals who are happy to work closely with clients and adapt to changing site conditions.”

How to avoid problematic pavement lift caused by trees in urban areas


How to avoid problematic pavement lift caused by trees in urban areas
By Joe Gooden, Consultant at Citygreen

The benefits of trees in urban environments are well established but, without sufficient forethought, trees in hardscaped areas can cause all sorts of damage to surrounding infrastructure. The most common – and visible – is the occurrence of ‘pavement lift’, whereby roots from a growing tree cause the pavement to lift, separate, and sometimes come loose. As well as looking unsightly, this is a real problem for councils as it poses a significant tripping hazard and liability risk.

So, how can you avoid pavement lift in hardscaped urban areas?

Step 1 is to provide enough room and uncompacted soil volume below ground for tree roots to grow unimpeded. The key is finding a soil cell that offers sufficient structural strength to support the pavement above, and that has large apertures for tree roots.

Step 2 is equally important, and that is allowing enough space between the stem of the tree and the surrounding pavement, to ensure the ‘zone of rapid taper’ (the primary structural roots extending out from the trunk) has sufficient room to expand as the tree grows. But, how do you calculate the space required between the tree and the nearest hard surface?

Ross Clark, Managing Director of Trees Impact Group, coined this handy formula.

Planting distance = 3.5 x DBH

Zone of Upheaval

diagram courtesy of Trees Impact

Planting distance is measured from the centre of the planting pit, and ‘DBH’ is the estimated Diameter at Breast Height of the tree when mature. Of course, the planting distances generated by this formula are estimates only, dependent on species, and should be used only as a guide or target. For specific advice, we recommend you seek the services of a consulting arborist.

For big trees, particularly those with a buttressed root pattern (such as the Ficus Benjamina / Hills Fig) incorporating the required aperture size into the surrounding landscape sometimes simply isn’t possible. In those instances, rather than having a huge open space surrounding an immature tree, a dedicated ‘sacrificial zone of pavement’ can be implemented. The root system will break up the pavement in this zone as the tree grows, which then gets cleaned up and taken away. This is far more preferable than the alternative of topping up surrounding asphalt and rubber crumb, which is not cost effective nor good for the tree’s health.

We can see this concept of a dedicated ‘sacrificial zone of pavement’ at work in one of our recently-completed projects in Laman Street, Newcastle, shown within the concentric square paver band – whereby the Landscape Architect incorporated a break-out zone around the tree, and our modular StrataCell system below ground.

Laman St Newcastle - construction of break-out zone

Laman Street visualisation

In combination, this solution will ensure both the healthy growth of the trees and the longevity of the surrounding pavement, for the safety and enjoyment of all.

Want to learn more? Check out:

Mann, Gordon – Sidewalk and Roots, Mitigating the Conflict—An Overview by Gordon Mann, Consulting Arborist, Mann Made Resources, Auburn, California
Tree Roots and Infrastructure Damage by Dr. Kim D. Coder, University of Georgia

Viva “Green” Las Vegas




Viva “Green” Las Vegas
by Ashley Carlton

When thinking of Las Vegas images of an iconic urban landscape come to mind. What doesn’t come to the forefront is the lavish greenery and supple urban forest. Citygreen strives to create change amongst a grey landscape in a tough subtropical climate.

Proud to announce an exciting project in the Las Vegas’ urban forest, Citygreen places it’s most cutting edge technology in the ground to support a greener landscape. Joe Gooden of Citygreen says, “What we’re hoping to highlight here is the way we can make street trees grow in tough climates when we give them better soil conditions.”

Las Vegas inhabits part of the Mojave Desert, which means blistering days of sunshine, where 60% of the year exceeds temperatures of ninety degrees fahrenheit. Given these strained conditions trees have little chance of success, the time for innovative solutions is now.

The health and presence of a green urban forest has tangible and intangible benefits that can’t be overlooked, including the mental health and success of it’s residents, a measurable increase in property value and subsequent commercial benefits.

Soil cell 2

As the Las Vegas council seeks innovative solutions to enhance their cities landscape, furthering an already vibrant resident and tourist population, products such as Citygreen’s Stratacell will allow for strong tree growth, via robust tree pits, rooting in healthy soil conditions. In conjunction with Landscape Architects, Alta Planning, Engineers, CA Group, and Landscape Contractors, GTI Nevada, Citygreen is excited to further study the results of its sustainable landscape solutions and will continue to share the feedback, progress reports, and case studies as the installation of this ground breaking project continues. Stay tuned for further insights to come in the coming months.

Frew Park Thrives with Water Sensitive Urban Design



Frew Park Thrives with Water Sensitive Urban Design
by Sally Cameron

Situated on the hallowed grounds of the iconic Milton Tennis Centre, Frew Park is a state-of-the-art 3.5 hectare parkland named after the father of Queensland Tennis, Robert Dickson Allen Frew. While nothing remains of the original tennis centre, which opened in 1915 and closed in 1999, there are numerous features which honour its history, including the main playing green named after Brisbane-born tennis star, Wendy Turnball, and sculptures of children with tennis racquets and spectators holding ice creams.

In addition to the grassed playing field and tennis courts, the park’s major drawcard is the futuristic playground which features a net climbing wall, fireman’s pole, a network of linked tunnels, interactive sound and music play, and a mega tube slide. Nearby, there is a cluster of BBQ and picnic pavilions for family gatherings and birthday parties.

Trees play an integral aesthetic and practical role at Frew Park, with Brisbane City Council engaging Citygreen to consult on a water sensitive urban tree solution for the Frew Park car parking bays and hardscaped plaza.


Adrian Nguyen, Landscape Architect at Brisbane City Council, said, “The challenge with these areas was that they presented adverse conditions for the healthy growth of trees. The engineers weren’t keen on permeable paving, so instead we opted for strip drains to collect runoff from the carpark to provide passive irrigation. Citygreen provided a cutting-edge passive tree watering system featuring the latest in water sensitive urban design, combining the Rootrain Arbor Vent Dual Inlet system for deep watering and Stratacells for deep aeration. Stratacell modules were used in the carpark where we planted three Elaeocarpus trees, and in the plaza where we planted nine Harpullia trees, ensuring the trees have adequate uncompacted soil despite the load from the hardscaped surface above.

Stephen Williams, Project Manager at Epoca Constructions Pty Ltd, said, “This was a really innovative solution, whereby each of the trees double as drainage bases. As a result, they’ve required very little maintenance from us. In fact, apart from giving them a bit of water in the first few weeks, we haven’t had to do anything to them – they look after themselves, which is fantastic.


“In addition to the actual product, the Citygreen guys we worked with made a lasting impression. They were always happy to discuss the install and provide advice, and often popped into site of their own accord just to see how everything was progressing. They obviously really believe in their product, and are excited about being involved and seeing the technology come to life. Their positivity and proactivity was really impressive.”

Adrian Nguyen echoed this sentiment, saying, “We were really impressed with Citygreen’s on-site construction input. This system was new to the contractor, so Citygreen played an active role prior to and during construction, ensuring the contractor understood the construction methodology and knew how to build the system properly. Six months down the track, the trees are all in good health and they’ve definitely grown, so I’d be happy to recommend the StrataCell system to others.”


Stephen Williams concluded by saying, “The trees have clearly grown above average performance, which is testament to the success of the water sensitive urban design of this solution. For this kind of urban environment where a passive tree watering and aeration system is required, I’d definitely recommend the StrataCell system. It’s a great product, and the guys are great to work with. We’ll work together again, I’m sure.”


City of Edmonton Strengthens Its Core


City of Edmonton Strengthens Its Core
by Ashley Carlton

In September 2016, the second largest city in Alberta, Canada will celebrate the completion of a progressive stormwater management project in its city of Edmonton. Prior to its completion, a project update offers some compelling and exciting information on the project’s progress.

Taking place just northwest of the downtown core on 105th Street, Canada’s “festival city” has partnered with ISL Engineering, Carmack’s, a large civil contractor, and Citygreen West, an international leader in sustainable landscape systems. The project’s stakeholders focus on the revitalization of existing streets, sidewalks, and curbs that are, “well past their lifetime,” reported Matthew Biggs of Citygreen West.

Edmonton’s city limits holds seven sectors, with the mature downtown sector at its core. Surrounding it are six suburban neighborhoods. The majority of the buildings and infrastructure built prior to the 1970’s, and the new generation is taking steps to revitalize their city infrastructure and take an active role in the management of stormwater.

“Primary goals of the city are to remodel the streetscape as part of a plan to upgrade the area…The present street is an aging warehouse and industrial zone, which is being upgraded to a modern, sustainable multi-family dwellings,” said Biggs.



Upgrades are meant to allow for a flourishing urban forest, in conjunction with a responsibly planned stormwater management system that proves successful, “by directing street stormwater into large soil filled tree pits and draining it through collection pipes at the base of the tree growing areas,” said Biggs. The ultimate solution for Edmonton’s design challenges is Citygreen’s innovative Stratavault soil cell system.

The open matrix design boasts unique advantages that presented solutions to challenges and considerations like project cost, transport, installation, as well as the need for green infrastructure and stormwater quality objectives. The cell’s components are able to nest inside one another and are constructed of lightweight polymers, allowing for significantly lower costs in freight. Once the product is at the installation site, their simple construction doesn’t require unique tools or specialized labor, thus also allowing for a smaller task force.

The Stratavault’s open design allows for the unhindered installation of all necessary subterranean construction, such as water pipes. Even so, with its “quick and simple to assemble” matrix design, the cell system continues to provide the surrounding sidewalks, “with sufficient structural integrity to withstand traffic loads,” Biggs noted.


The open voids allow for tree roots to establish and grow as naturally as possible in the oxygen-rich soil, a thing of the future compared to conventional single slab planters. These conventional builds have soil that is too compacted for natural root growth, or for rainfall to be properly absorbed and redirected, resulting in unhealthy or dying trees, eroding landscaping, and ultimately, unnecessary expense in the city’s green infrastructure plans and initiatives.

With 105th Street’s central location inside the city, the active efforts to reduce the damaging effects of unmanaged stormwater levels require large pipe sweeps to be safely integrated into the Stratavault installations. In short, Citygreen’s cell systems are offering the city of Edmonton solutions to all the project’s concerns and goals with a single product.


An innovative process “approved by the Stratavault manufacturer” was proposed featuring 200mm, eight-inch water pipes, which were able to be safely integrated and routed through the cells, “with minimal interruption to the structure.” Because the Stratavaults are interlocking, void of bolts or other connectors, individual single leg sections of the matrix system can be removed for the pipe sweeps, leaving the top layer in place. The sidewalk structure is then reinforced with a bridging section layered on top of these particular areas. This engineering modification would not have been as likely with another form of green technology.

Since the project’s onset in May 2015, the first tree pits have been installed, and were backfilled with soil quickly and efficiently by Carmack’s subcontractor, 7M Landscaping.

In a final statement on the partnership with Edmonton’s city staff, Biggs reported that the installations are already showing positive results. “This retains the key feature of the Stratavault cell structure – it’s strength as a connected matrix….” just like the interconnecting streets and communities within the city of Edmonton itself.

This project was supplied by Citygreen West, ph (780) 462 5064