Townsville curb-side trees get a fresh start with Tree root protection and fertile soil

Citygreen® soil vaults have been used to ensure a healthy growing environment for new street trees in Townsville, QLD Australia, planted in an area that had suffered from poor quality, compacted soils.

Although irrigated, the trees that previously occupied the site hadn’t been performing well because they were set in soils that were lacking in nutrients.

“The trees preferred loose sandy soil, but had been planted in clay,” said Andrew Froggatt, Landscape Planning Supervisor, Townsville City Council.

The new trees have been planted curb-side at a newly-reconstructed drop-off zone at the entrance to Oonoonba School, situated in the middle of the developing suburb of Fairfield Waters.

A large number of daily pick-ups and drop-offs of children by parents means a great deal of foot traffic between and around the trees, resulting in a lot of compaction of the surface.

Supplied by Citygreen’s key Australian distributor – Arborgreen Landscape Products – these RC120 structural soil cells were buried adjacent to the trees beneath the new footpath, providing cavity spaces for the roots to grow into and preventing them being starved of vital nutrients, including water and oxygen.

The RootCell cavities were filled with quality blended soil, then the structures were covered with organic mulch containing RootRain irrigation lines. Grass growing between the tree sections will spread over some of the mulch in time.

Root Director linear root barriers were laid adjacent to the outer edge of the soil vaults to prevent root encroachment into underground services, the footpath and the car park kerb.

“The soil vaults will definitely help the growth of the trees by preventing the soil being compacted, as well as offering a better type of soil,” Mr Froggatt said.

The 12 new trees are a sturdy Australian rainforest species Fair Hills Gold (xanthostemon) that can survive without irrigation after the first two or three years. A small species without invasive roots, the tree was deliberately chosen to protect underground services such as water mains.

Drip irrigation will be used during Townsville’s dry season, which can last nine months of the year.

Townsville City Council has previously used Citygreen soil cells in Stanley Street in the CBD. “This was the first site we used them on. The trees, which are also Fair Hills Gold, are doing really well,” Mr Froggat said.

The Stanley Street project employed Citygreen’s 1.8 metre Ullswater tree guards to protect the growing trees. The guards will be removed in a year or so when the trees are sturdy enough to survive on their own.

Citygreen’s latest generation structural cell, called the Stratavault , boasts wider apertures between internal columns, larger overall module size, advanced stacking and nesting capabilities, and super-efficient installation times. Available in high and lower strength versions, the high strength Stratacell is up to three times stronger than any other module of a similar function, in the market.

For more information visit www.citygreen.com/ or send an email to info@citygreen.com/