Alterations to the road network in and around Keighley, Yorkshire were undertaken to alleviate the traffic gridlock that was becoming a feature of the town centre.
Plans included the provision of a public open green space. Existing street trees had to be removed to allow for the roadworks, so new trees were specified in large soil volume tree pits, supported with GreenBlue Urban RootSpace soil cell systems.
To maximise the value of the new tree planting, it was decided to use these tree pits as stormwater attenuation and treatment pits, taking water from the carriageway, passing it through a stone layer on the top of the tree pit and then filtering it down through the Arborsoil Hydro soil mix provided for the root growth. The water then transferred through a clean stone layer to an underdrain to a stormwater drain. This method of conveyance gives an acceptable level of pollutant removal and slows the water down so that the existing drainage network can cope with the increasingly violent storm events.
The trees have shown significant growth over the past two years, which is typical for trees planted in these systems; uncompacted soil with good porous surfacing allows maximum gaseous exchange, and every storm event washes fresh nutrient into the tree pit.
The project brought together irrigation and aeration, root management for guidance along utilities, mesh, Geonet and ArborSoil Hydro, specifically blended as a result of research and testing perfect for SuDS tree pits.
This project clearly displays how imaginative tree planting can provide numerous benefits without high levels of cost – and continue to provide these benefits for decades.