GREEN & BLUE INFRASTRUCTURE
Liverpool Rain Garden . Credit : Martha Redman STRI
Upper Pit Street before . Credit : Martha Redman STRI
Blend 2 is Green-tree ’ s High Performance bioretention soil , which allows a greater percolation rate , whilst maximising the ability to sequester pollutants from the surface runoff .
Blend 3 is an experimental custom soil containing brick fragments , that in theory should aid permeability , whilst improving filtration . It will be interesting to see how this performs against the more traditional mixes .
The performance of each bed will be monitored by Liverpool City Council , in collaboration with the University of Liverpool and The Merseyside Forest organisation .
The various testing parameters will include :
Green-tech involvement : Green-tech has been manufacturing soils since 2004 under the brand name Green-tree . These soils are widely regarded to be amongst the best in the country , suitable for a wide range of standard and specialist landscaping purposes .
Green-tree offers a wide range of lightweight green roof and podium substrates , as well as rain garden and bioretention soils , all using their British Standard manufactured topsoil as a base .
In this instance , as Liverpool had no previous experience using rain gardens as a “ green solution ”, it was proposed to create a test area to demonstrate what could be achieved .
Working in partnership with the Sports Turf Research Institute ( STRI Ltd ), Green-tech supplied three different bioretention blends for testing :
Blend 1 is the standard Green-tree bioretention mix , featuring screened silica sand , green compost and blown clay particles . This provides sufficient permeability to avoid waterlogging , while at the same time providing enough nutrients and organic matter for the shrubs and other vegetation .
1 . Water flow during storm events and the velocity of discharge .
2 . Using moisture probes to monitor moisture and temperature levels between the beds .
3 . How the different soils affect : vegetation , pollinators , water quality ( and pH levels ) and air quality
Commenting on this project Martha Redman , Chartered Landscape Architect from the Sports Turf Research Institute said , “ STRI have worked with Green-tech for several years now . Throughout this time , Green-tech has provided invaluable support in developing and delivering customised substates to meet our ever changing , often challenging , design requirements across a variety of sectors .”
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