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Planting for the Future
In 2013, Twelve Pin Oaks (Quercus palustris) were planted into Citygreen’s Stratacell soil vaults, which provided uncompacted soil volume beneath the parking bays. Stead noted the
rationale as follows:
“The project used Stratacells beneath the car parking. This allowed us to provide more soil volume for the trees whilst not taking up large areas for planting and retaining car parking. The pervious paving treatment allows water to enter the planting trenches and water the trees without the need for irrigation.”
When Casey Market Town officially opened in 2016, the trees were already showing signs of strong, healthy root establishment, in comparison to the same stock planted without the soil vault technology in the street verge.
Proof of Concept: 12m Connected Tree Canopy
By 2025, the design decision has been a resounding triumph.
Recent images show the Stratacell car park trees reaching 12 metres in height and 9–10 metres across, shading four bays at once. Their dense crowns and strong form reflect excellent health.
Across the road, the verge-planted trees remain smaller, around 6–7 metres high with canopies only 4–5 metres wide. The comparison underscores how critical rooting volume, uncompacted soil and passive irrigation have been to long-term success. For local governments and developers aiming to deliver meaningful climate outcomes in the decades ahead, Casey offers a powerful reminder of what’s possible when design decisions are guided by long-term performance rather than short-term constraints.
Using the Burnley Tree Valuation Method, each car park oak valued at about $5,500 in 2017 is now worth $30,000+ ,with the trees in verge now valued the same as the 2017 Stratacell trees ($5,500). The growth represents not just ecological success, but tangible financial return on investment.
Durability of the System
Sceptics in 2013 wondered whether the system would hold up under daily retail traffic. A dozen years on, there is no evidence of root heave or structural failure of the soil vaults.
The vault matrix continues to carry vehicle loads while protecting the soil beneath. Maintenance has been limited to pruning and occasional paver
replacement.
As Stead summarized, “The benefit of working with Citygreen and its technologies is the ability to achieve win-win outcomes with good soil volumes
and growing conditions provided to trees in an urban setting whilst not taking up valuable space at the ground plane.”
Community and Commercial Benefits
The success of the green infrastructure has rippled far beyond the trees themselves.
The landscaping has become a defining feature of Casey Market Town, elevating it above the purely functional.
Property manager Brianna Nix reflected on the public response: “Never have I worked with a centre where the feedback from visitors is so positive. Visitors remark on the shade, seasonal colour, and comfort, and they linger longer because of it.”
The development won the 2017 ACT Commercial Architecture Award, with judges highlighting the public realm and canopy as central to its success.
Cooling, Comfort, and Stormwater Management
The innovation of pairing permeable paving with soil vaults is felt most acutely in summer.
Pavement beneath the trees is 10–15°C cooler than exposed bays, and shoppers naturally choose shaded spaces first. Instead of heat and glare, visitors experience comfort and relief.
Rainfall continues to infiltrate the paving and recharge the soil vaults, keeping trees watered without the need for permanent irrigation. The soil acts as a sponge, filtering pollutants, supporting tree growth, and reducing pressure on the precinct’s stormwater system.
Lessons and Legacy
Casey Market Town is more than a development success. It is a proof of concept.
What was innovative in 2013 is now widely recognized as best practice: treat trees as infrastructure, give them the soil conditions they need, and integrate water-sensitive design from the start.
The lessons are clear:
- Trees can thrive in car parks when they are designed as ecosystems rather than sealed surfaces.
- Communities value and reward places that are shaded, green, and comfortable.
- The economic, climate and livability benefits can now be seen in the financial value of the trees, reinforcing the case for upfront investment.
