The development of a new retail park in Birmingham presented an opportunity for Green-tech to  showcase its ArborRaft tree pits.

THE Battery Retail Park at Selly Oak is located on the former site of the Birmingham Battery and Metal Company steel factory, first established in 1798. In this case, the term ‘battery’ refers to the method of forming metal, not the manufacture of batteries as commonly thought.

Located approximately three miles from Birmingham city centre, the site has undergone a recent refurbishment, including the development of a new retail park, Sainsburys superstore, and student accommodation, all sited around the main customer carpark. 

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A major part of the project for the contractors was the reclamation of the ground and cleaning up a very toxic site, before any development could commence.

The project comprised of nearly 40 tree pits over two phases between 2018 and 2020. The first phase was contracted to Bernhards Landscapes of Warwickshire, and the second to McPhillips (Wellington) of Shropshire. Both have been working with arb supplier Green-tech for around 15 years.

The tree pits were set into soft central reservations around the main car parking area, although to get the required rooting volume to ensure healthy establishment and future growth, the tree pits extended out under the parking bays to some extent.

Green-tech has been manufacturing its range of Green-tree soil for nearly 20 years, and over 400 tonnes of clean, manufactured ArborRaft topsoil and subsoil was supplied for the tree pits. In order to use a nice friable, organic topsoil underneath the paving, the contractors opted for Green-tech’s ArborRaft tree pit support system, rather than a traditional, plastic-heavy, deep-pit system.

The ArborRaft acts as a sub-base replacement, supporting the paving above, pedestrian, or vehicular, whilst protecting the soft soil below from risk of compaction. It has three big advantages over traditional deep-pit crate systems. Firstly, it sits over the top of the tree pit, taking its structural support from a 500 mm wide ledge cut into the surrounding formation ground, meaning there is no plastic whatsoever in the actual rooting area of the tree pit. Secondly, its shallow profile, just 150 mm deep, means that there is rarely any conflict with underground services – it isn’t deep enough. Thirdly, ArborRaft uses less than a third of the plastic of traditional crate-style tree pit systems, so it’s better for the budget and the environment.

Each tree pit also contains a strap anchor to keep the trees stable during the all-important establishment phase, along with a mona irrigation rings. In this instance, to provide even more protection from the risk of vehicular damage, the trees were also stabilised with double-staking, cross-bar, and soft rubber ties.

Forestry Journal: The ArborRaft System acts as a load bearing support while directing the tree’s root growth away from the surface and towards nutrient-rich soil.The ArborRaft System acts as a load bearing support while directing the tree’s root growth away from the surface and towards nutrient-rich soil. (Image: Supplied)

Alasdair Innes, Green-tech specification advisor, said: “We were delighted to contribute to such a high-profile scheme. We recently visited the site nearly four years after the first trees were planted, and although it was autumn, the trees still look happy and healthy.

“It is nice to see silver birch being used, as the white bark helps to lift the muted colours of the ground planting.”