What we did
The contracting work was awarded to Hull-based PBS Construction, who are a family business with strong ties to Bridlington. PBS asked Green-tech Specifier to provide a structural tree pit system that would enable the trees planted within the hard landscaping around the plaza to establish without risk of soil compaction.
A total of twelve trees were planted, eight on the pedestrian plaza area immediately outside of the main entrance, and four sited alongside the taxi rank. To help the trees achieve their full potential, we wanted a good organic topsoil for them to grow in, as well as enough rooting volume. The challenge with planting in any hard landscape is how to use the good stuff underneath the paving, without the paving sinking and compacting the soil. This is where Green-tech’s Geo-Cellular Raft System sub-base replacement system comes into its own.
Rather than using a traditional deep-pit crate system that fills the tree pit down to the base, Geo-Cellular Raft System works on a combined raft/bridging principle, and sits across the top of the tree pit, leaving the rooting area itself completely free of plastic. Not only is this better for the tree, but it also means there is no conflict with underground services such as water, gas, electric or comms.
The Geo-Cellular Raft System can take a static vertical loading of 70 tonnes/m2, so can be used under vehicular or pedestrian paving with no concerns about the paving sinking, or the soil underneath becoming compacted. This means that we can use a soft, friable, organic topsoil in the tree pit, rather than a heavily sand-based structural tree soil.
The trees were planted in individual tree pits, and over 300 tonnes of Green-tech’s manufactured Green-tree soil was delivered to site in stages as required. Green-tech also supplied each tree pit with tree anchors, Mona irrigation rings topped with aluminium Piazza filler inlets, and Fortress tree grilles, which are designed to take paving sets for a flush surface finish with the surrounding paving.