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Case Study

Canon Green Court, Salford, Manchester

Green-tech Specifier advise on Geo-Cellular Raft System in helping Salfords green infrastructure.

Project Details


Canon Green Court


Salford, Manchester, England


August 2021

About The Project

Canon Green Court, a 1960s apartment block recognisable to some TV viewers by its distinctive blue façade, has seen its fair share of drama over the years, appearing in TV dramas such as ITV’s Prey and Channel 4’s No Off ence. Over the years however, time had taken its toll and the building was earmarked for essential improvement and refurbishment.

The improvements include landscaping of the extensive grounds, and an additional 11-storey building to house 108 new affordable homes of one and two-bedroom apartments. Built by main contractor Willmott Dixon, this is the largest affordable housing development in the area.

As well as the communal grounds, the frontage along Blackfriars Road was improved by planting 11 Liquidambar Slender Silhouette trees, utilising a 58-metre-long trench to provide plenty of good quality shared rooting space for the trees. These trees, which can grow up to 18 metres whilst retaining a slender 2 metre spread, will carry out a vital role in absorbing carbon and other air-borne pollutants.

As well as helping to clean our city air, trees also attenuate water runoff, reducing the amount of storm water that goes down our rain gullies and into our already over-burdened sewers. As we build more, we fall victim to the Urban Heat Island effect; where the heat that builds up throughout the day is radiated back from our solid surfaces, increasing city temperatures by around 7°c. Trees counteract this heat by providing shade and they also give off cooling water vapour via transpiration.

What we did

Stephen Martlew Landscape Architecture specified the tree pits to incorporate Green-tech’s Geo-Cellular Raft System, a geo-cellular tree pit solution that enables the use of a good quality, friable, organic soil within the tree pits, as opposed to structural tree sand.

The landscape contract work was awarded to Beech Landscape (Developments) Ltd, with whom Green-tech Specifier have a twenty-year working relationship. Nick Abbott, founder of Beech Landscape had used the Geo-Cellular Raft system before and appreciated the benefits of having a tried and tested system to work with.

The area above the trees is a block-paved extension of the pavement alongside a busy main road. It is therefore imperative that a system was put into place that protects the soil below from compaction whilst supporting the paving above; at the same time without encroaching on underground service lines or filling the rooting area with plastic.

Green-tech’s Geo-Cellular Raft System is a highly rigid, yet shallow sub-base replacement, capable of supporting up to 70 tonnes per square metre. Requiring a mere 500mm wide shoulder around the edge, it acts as a raft, spanning the tree pit or trench without any plastic encroaching into the rooting zone. Using recycled polypropylene with a 95% void ratio, it also acts as an air void, bringing aeration closer to the roots.

One of Geo-Cellular Raft System’s key advantages over traditional deep pit crate-style systems is the 150mm shallow profile. This came into its own when the installation team discovered a plethora of Victorian pipework less than half a metre underground. Nick stated that if they had been using a crate-style system, it would have given them a real headache and taken a lot longer to install.

Each tree within the trench was completed with Mona irrigation tanks, tree anchors, and over 120 tonnes of Green-tech’s Green-tree British Standard subsoil and specially formulated Geo-Cellular Raft System topsoil, to give the trees the best chance of establishment.

“We have worked with Green-tech for years and have a great relationship, not only for tree pits, but all sorts of landscape supplies. This particular product is a really nice system to work with, and anything that helps reduce plastic in the ground is a good thing.”

Nick Abbott – Beech Landscape (Developments)Ltd