5.0 Case Studies
Total Page:16
File Type:pdf, Size:1020Kb
SuDS In London: A Design Guide Chapter 5 - 110 5.0 Case Studies Barnes Wetland Centre Chapter 5 - 111 Case study index The case studies below offer local and London under 500m² London over 0.2ha strategic SuDS examples to demonstrate the versatility of sustainable drainage in various 5.1 Priory Common 85 m² 5.14 Queen Caroline Estate 0.23ha contexts. Many are examples from London, 5.2 Dale Court 90m² 5.15 Australia Road 0.26ha but there are also studies from elsewhere, that 5.3 Museum of London 100m² 5.16 Crown Woods Way 0.26ha are exemplars applicable to the Capital. They 5.4 Upminster Bridge swale 400 m² 5.17 Hackbridge 0.27ha are described and ordered by size. 5.5 Kenmont Gardens 435m² 5.18 Goldhawk Road 0.27ha 5.19 Firs Farm 0.48ha 5.20 Salmons Brook 0.77ha London under 2000m² 5.21 Richmond Park 1ha 5.22 Coulsden Bypass 34ha 5.6 Central Hill 640m² 5.23 Dagenham SIP 142ha 5.7 Derbyshire Street 765m² 5.24 LuL depot roof, Middlesex 125m² 5.8 Renfrew Close 900m² 5.9 Islington Town Hall 1000m² National & International 5.10 Rectory Gardens 1000m² 5.11 Hollickwood School 1100 m² 5.25 Clay Farm, Cambridge 109ha 5.12 Talgarth Road 1200m² 5.26 Alnarp, Sweden 0.37ha 5.13 Mile End Green Bridge 2000m² 5.27 Benthemplein, Netherlands 0.95ha 5.28 Rue Garibaldi, Lyon, France 15ha 5.29 Bo01, Malmo, Sweden 85ha 5.30 Augustenborg, Sweden 320ha SuDS In London: A Design Guide Chapter 5 - 112 5.1 Priory Common rain meadow Location Priory Common Objectives London Borough of Haringey • Intercept road runoff pollutants at source Extent 85m² and use the existing landscape to allow Cost £48,000 (Construction only) ‘interception loss’ (ie, prevent water from Date 2016 reaching the ground) for everyday rainfall Credits London Borough of Haringey • Clean and cool run-off during summer Thames21 when the watercourse is most susceptible Robert Bray Associates to the effects of pollution and water temperature increases (which inhibits the SuDS Components ability of water to carry dissolved oxygen) • Filter strip • Infiltration basin • Channels Actions and results • Runoff is diverted at the surface into a gully Summary in Redston Road and collected in a five-sett Green space enhancement and re-purposing channel that directs water onto the grass for surface water interception and infiltration. verge along Priory Road • Verge re-profiling carries water for its full Project Description length until it reaches the sewer Next to Priory Road is a linear green space • Early observations indicate that water with mature plane trees planted along the flows quickly into the rain meadow but roadside. The verge is about 75 metres long slows as it travels through the grass, and was highlighted as a site to deal with soaking into the tree-lined verge before surface runoff from the road, via a sewer reaching the letterbox outfall to a road gully. connection directly to the River Moselle. This Performance will improve as the meadow project is part of a suite of SuDS schemes grows locally that will cumulatively improve water quality. Image courtesy Robert Bray Associates Priory Common after installation Chapter 5 - 113 Benefits • This simple SuDS retrofit shows how an existing urban green space can bring significant benefits to unprotected urban watercourses • Surface collection of runoff avoids any significant excavation or spoil for removal • Surface dressing with topsoil and low earth banks (bunds) have minimum impact on the trees with simple wildflower meadow seeding for open soil areas • Trees will be watered in times of water- stress, base flows in the soil will be Love the Lea campaign, Thames 21 enhanced and the River Moselle will be protected from urban runoff • High intensity summer storms will be diverted from the sewer and cooled before release to the river • Monitoring will show the extent of interception loss and the protection offered to the River Moselle Lessons Learned • Importance of contractor selection • The value of expert supervision • How sites, that might otherwise be considered unsuitable for SuDS, can provide benefits with minimum intervention • The client partnership with Thames21 Images courtesy of Robert Bray Associates and Haringey Council are considering monitoring opportunities Conveyance of water through the scheme SuDS In London: A Design Guide Chapter 5 - 114 5.2 Dale Court Location Hornsey Actions and Results London Borough of Haringey • Rainwater from the roof of the building Extent 90m² is re-routed away from the drainage Cost £20,000 (Construction only) network following rainfall by disconnected Date 2016 downpipes. The flow is diverted into two Credits London Borough of Haringey detention basins created within the existing Homes for Haringey lawn area, designed to accommodate one Thames 21 in 100 year rainfall Greysmith Associates • Rainwater is allowed to infiltrate the ground, but also return to the existing drainage SuDS Components network via buried outlet pipes. This • Bioretention basins process reduces peak flow. The wildflower • Downpipe disconnection turf also takes up water as it infiltrates into the ground Before Summary • Maintenance is carried out by the existing Transformation of amenity lawn to biodiverse grounds maintenance team and has been community asset. reduced as the mowing regime for the wildflower turf is less than that for the Project Description former amenity lawn Dale Court is a small block of flats with an area of lawn between the building and the street. It Benefits is enclosed by a low brick wall and features a • Inhibits the flow of storm water runoff into number of trees and a perimeter rose bed. the combined sewer system • Creation of a small area of wildflower Objectives meadow that improves biodiversity and is • Reduce flash flooding within the catchment more attractive of the culverted River Moselle, a tributary of • Water capacity of the SuDS system can the River Lea to. This was part of a plan to withstand a one in 100 year rain fall event Images courtesy of Greysmith Associates deliver a number of local SuDS projects in this catchment. Visualisation Chapter 5 - 115 Lessons Learned • Active engagement and discussion with residents has raised awareness of the issues • The scheme makes good use of an otherwise unremarkable and unused area of lawn • Small scale interventions make a difference as part of a strategic network of projects • The effectiveness of the SuDS scheme has been demonstrated by the amount of rainwater draining into the rain gardens. The scheme has been designed to allow for flow-monitoring equipment to be installed later if required Plan SuDS In London: A Design Guide Chapter 5 - 116 5.3 Museum of London Location London Wall City of London Objectives Extent 100m² • Improve attenuation of rainfall and reduce Cost - runoff entering the storm drain system Water attenuation performance of the Museum of London green roof Date 2011 • Improve biodiversity Credits University of East London GLA Drain London Programme Actions and Results • Bauder were commissioned to design and SuDS Components install living roof at the northwest corner of • Living roof the museum • The roof area was divided into two by an Summary impermeable barrier, creating two separate Living roof source control and monitoring hydrological units (sub-catchments). This provided an ideal location for comparative Project Description rainfall runoff measurements on the green As part of a sustainability initiative at the roof and the existing control roof Museum of London, a series of living roofs • A range of roofs, from biodiverse systems were installed across the museum’s roof during with topographical interest, to wildflower a programme of waterproofing renewal. and sedum mat systems, was used. This Supported by the Greater London Authority’s variety, in terms of their scale, levels, Drain London programme, this installation shading, and aspect, created an important included a range of roofs from biodiverse biodiverse urban habitat systems with topographical interest to • To monitor the water attenuation wildflower and sedum mat systems. The performance of the living and control roofs, complexity of roof systems at the Museum of it was necessary to quantify the volume London meant a variety of living roofs could and rate of rain falling onto the roof and the be installed in terms of scale, levels, shading volume and rate of rainfall runoff entering and aspect, thus creating an important urban the storm drain system of the museum resource for a range of biodiversity supported • The living roof was established in 2011 and University of East London Assessment by the living roof habitat. Chapter 5 - 117 monitoring began in 2014 Benefits • Living roof outperformed control grey roof in terms of rainfall attenuation • Reduced peak flow and amount of rain discharging from the roof Lessons Learned • Much of the rainfall on the roof and subsequent runoff was within the lowest range of the v-notch gauge, where the flow rate could not be captured accurately Images courtesy of University of East London After SuDS In London: A Design Guide Chapter 5 - 118 5.4 Upminster Bridge swale Location Upminster Bridge A London Underground Power Upgrade London Borough of Havering Project, involving the construction of new Extent 400m² substation, presented the opportunity to trial Cost Trial scheme an experimental SuDS scheme. This included Date 2015 two swales with associated tanks and v-notch Credits London Underground weirs. One receives water from the new sub- Environment Agency station roof, the other from adjacent London Green Infrastructure Agency Underground tracks. Funding was provided Environmental Scientifics Group by the Environment Agency with London Environmental Protection Group Underground Limited contribution in kind. SEL Environmental ITM Monitoring Objectives • Better manage water quality by improving SuDS Components remediation capabilities • Swale • Mitigate rail infrastructure flood risk • Outfall/runoff interception • Enhance local biodiversity No disruption to service during construction Summary Actions and Results Swale construction for increased on site • Surface water from the railway lines and attenuation and water treatment from the outflows of the sub-station roof was attenuated.