Renfrew Close, Beckton, London Borough of Newham, E6 5PG Description The Renfrew Close Rain garden is a community scale retrofit project. Renfrew Close was chosen for this project as London Borough of Newham were a willing council, who both owned the land (estate), and were supportive of this work being carried out on their land. London Borough of Newham (LBN) was also happy to pay for the maintenance costs after completion. The site also fitted funding criteria of it being a community space with a supportive community. The project was designed as a demonstration project to showcase how SuDS can be incorporated into existing areas. The system comprises four rain garden basins located within the central amenity grass areas of the surrounding social housing blocks made up of approximately thirty six flats. The rain gardens receive water from disconnected roof downpipes and from the impermeable surfaces at ground level (through lined conveyance channels), thus reducing the volume of rainwater from the site to the sewer network. Two of the rain gardens are sized to accommodate a 1 in 10 year rainfall event. The ornamental rain garden is designed as 1 in 100 year +30% (to accommodate capacity for a climate change event) with a clearly defined 1 in 2 year central planted basin. The productive rain garden is sized for a 1 in 1 year event only and was designed for use as a space for residents to grow their own food. Main SuDS components used
Shallow rainwater conveyance channel
Shallow detention basin
Figure1: Renfrew Close rain garden design (c) Robert Bray Associates
Figure2: Ornamental rain garden (early after installation) showing a channel bridge under a pathway.
Figure 3: Nature play rain garden (early after installation) showing wide shallow grass basin around main rain garden basin.
The SuDS chain incorporates existing Thames Water (TW) surface water sewer outflows as exceedance control. Water is diverted from a non-permeable area of 915m 2 (750m 2 roof and 165m 2 road).
Figure 4: Wildlife Rain Garden leading to final outflow monitored by Thames Water.
The project demonstrates creative possibilities for rain garden design with a nature play rain garden incorporating balance beams and boulders to clamber on, an ornamental rain garden which brings aesthetic value, a wildlife rain garden that increases biodiversity, and a productive rain garden designed to provide residents with space to grow their own plants or vegetables. The design therefore provides an enhanced biodiversity, aesthetic and amenity interest for the local area.
As a retrofit project – the basins were designed without flow controlled drain-down outlets due to the high permeability of soils and shallow services which limited basin sizes. This allowed the basins to be connected to the on-site storm water drains for exceedance flows only (for rainfall > 1 in 10 year events for 3 basins and greater than 1 in 100 year events for 1 basin.) This may not be appropriate for other sites with differing characteristics such as lower infiltration capacity or where design will allow other methods for accommodating with exceedance flows.
Maintenance is managed by the LBNs Greenspace team and delivered on site by the councils grounds maintenance contractors.
Creation of attractive, biodiverse, playful and productive rain gardens for the community to enjoy, whilst reducing storm water loading on existing sewers.
Demonstration of a range of surface conveyance methods, path crossings, planting styles and resident uses that can be applied to other raingarden projects.
SuDS performance monitoring being used to inform future rain garden design. The project demonstrates potential for rain gardens to reduce a developments contribution to flooding which is applicable to both separate surface water sewer and combined sewer areas of London.
Introduction of the rain garden concept and a community gardening project to local residents and an adjacent primary school.
Successful partnership working between a Local Authority, NGO, University and Defra Arms Length Body.