Planning for the Future
When it came to the construction of a new car park to support community access to the newly developed Parramatta Aquatic Centre, it was imperative that urban heat island effect, stormwater management and tree success were addressed by the design, in line with the City of Parramatta’s environmental and sustainability strategy.
To effectively address the City’s objectives, Citygreen Stratavault soil cells were chosen to manage stormwater runoff and ensure the successful and prolific growth of 20 native trees to deliver over 100sqm of shade at maturity, across the car park, and continue their vision of a green corridor between the facilities and the neighboring Parramatta Park.
Photo taken July 2024, 12 months after planting.
Scope of the Project
The Parramatta Aquatic Centre offers state-of-the-art facilities for swimming and fitness for the local community. The $88M development was opened in 2023 after a two-year construction phase.
The centre is located close to Parramatta’s central business district and adjacent to Parramatta Park - a World Heritage-listed open space that sprawls over 85 hectares. The park is a hub for recreation, boasting gardens, historic monuments and outdoor spaces for events, sports and leisure.
To support community access, 186 car parking spaces, a coach area, and bicycle spaces were constructed adjacent to the Centre. The car park and Parramatta Park were planned to be connected via paths and cycle ways and a native species green corridor.
A total of 575 trees were specified for the car park project, and in excess of 50,000 shrubs and ground cover plants, primarily for the perimeters and green corridor connection. 20 native Tuckeroo and Kanooka Water Gum trees were specified for use within the hardscape car park, to be planted using Stratavault soil cells.
The open matrix design of the Stratavault soil cells allows for tree roots to grow and develop free from obstructions commonly associated with alternative planting methods such as structural soil, which consists primarily of rock and requires dense compaction to support the trafficable area above.
Conversely, the Stratavault system is a highly engineered structure with a high void-soil ratio, allowing the soil media backfill to be lightly compacted, while still delivering compliance for load bearing trafficable areas.
The lightly compacted soil media creates a healthy rooting environment for trees, water flow and air flow that allows them to reach their true mature size, sooner.
Damage to tree roots in car parks is a common problem as trees naturally develop a shallow root plate, Most tree roots are found in the top few inches of soil, contributing to the stunted tree growth you so often see in car park sites.
The Stratavault system manages where roots grow, encouraging a deeper level of root development, keeping them clear of being damaged or causing damage to other valuable infrastructure.
Each tree is further protected by a Duraplate Paseo Tree Grate for filtering and harvesting water flowing across the hardscape of the car park during rain events. The trees then naturally slow down the flow of water to the City stormwater drainage system and use the captured waster for passive irrigation, enhancing their growth, health and evapotranspiration cycles.
Continuous Tree Pit Design
Catherine Atkinson, Project Manager and Civil Engineer at Citygreen, oversaw the construction of the 11 island tree pits and the central continuous tree pit. The central zone, pictured above consisted of two layers and five rows of Stratavault to support nine Tuckeroo trees, anticipated to achieve an approximate height of 8-10m with a 6m canopy at maturity.
“The client and the landscape architect understood the importance of uncompacted soil volume for the success of the trees. In addition, one continuous tree pit was excavated for the central pedestrian island through the car park, giving the trees an even greater chance of success by extending the available root space, air and water flow through approximately 260sqm of Stratavault,” Atkinson said.
“The environmental credentials of Stratavault are superior to other alternatives, being locally manufactured in Sydney and made from 100% recycled plastic. So choosing Stratavault was also a positive way for Parramatta City Council to support local circular economy initiatives,” explains Atkinson.
