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Sustainable Urban Drainage

Aim: Reducing surface water flood risk

Water use

Aim: Reduce potable water consumption

Sustainable Urban Drainage

Changes to our climate are predicted to result in increased rainfall and greater risk of flooding. The Ebbsfleet Implementation Framework and Public Realm Strategy set out a water sensitive design approach that integrates sustainable urban drainage systems into Ebbsfleet’s buildings, streets, parks, gardens and open spaces to capture, store, distribute and absorb rainwater. This will reduce surface water run-off and support local drainage networks to function effectively, reducing the risk of flooding.

1. Collect and re-use rainwater in buildings

   Green and blue roofs can help to capture and store rainwater in more dense urban developments such as Ebbsfleet, and help to slow water entering into the wider landscape and drainage systems below ground.

   Provide rainwater storage systems for larger buildings and water butts or underground storage tanks.

   Consider how water management onsite can be connected to wider scale drainage systems within the street and neighbourhoods, to create fully integrated systems.

2. Incorporate SuDS into Ebbsfleet’s streets

   EDC’s Public Realm Strategy provides practical guidance on where SuDs should be incorporated into all scales of street in Ebbsfleet, from Level 1 boulevards through to the smallest of laneways.

3. Incorporate SuDS into Ebbsfleet’s parks and open spaces

   Incorporate a range of landscapes that capture stormwater and mitigate flooding through planting trees, hedgerows and buffer strips in all parks and landscape areas.

   Reduce surface water runoff on every site by designing in multi-functional sustainable urban drainage (SuDs) early on.

   Use the Design with Nature tool and the CIRIA / Susdrain guidance to identify the most appropriate locations and types of SuDS features.

4. Prioritise the use of above ground SuDs features that provide the public with a visual understanding of how water is conveyed within the public realm as part of their daily lives.

   Increase infiltration through improving soil structure, creating permeable surfaces.

   Include bioretention systems (e.g. rain gardens), swales, ponds, wetlands, detention basins, infiltration basins and soakaways.

   Aim to ensure all hardscaped surfaces are permeable where appropriate.

   Consider the opportunity to incorporate natural water processing systems such as wetlands into city parks.

Water use

Ebbsfleet typically gets half the rainfall of Sydney in Australia, and with our climate continuing to warm our water supplies are increasingly under pressure. Reducing the demand for water is imperative to managing our water more efficiently, so our communities are resilient to climate change.

1. Reduce water consumption

   Water consumption and capacity should be considered for all relevant materials and appliances used in the design.

   In very low energy buildings, the energy required for hot water can exceed the amount of energy required for space heating. Therefore optimisation of hot water systems is essential to ensure energy use remains low.

   Use low flow fixtures and fittings throughout homes / buildings, to all taps.

   Low flow showers can reduce water and energy by upto 30%, but need careful specification to ensure residents continue to perceive a high quality flow from their showers even with local-flow features, otherwise they will replace low flow shower heads with conventional heads, and the benefit is lost.

   Consider incorporating the new generation of ultra-low flush / vacuum toilets that can reduce water use by over 80%.

   Install leak detection systems to ensure water can be managed effectively.

2. Rainwater harvesting

   All buildings should include rainwater harvesting, to reduce water demand, and also minimise flood risk in the local area.

   Every home should provide as a minimum one water butt with a capacity of 200l or greater, that must be connected to the downpipe of the main roof.

   Aim to ensure the entire main roof is connected to rainwater storage, either in a centralised location, or to decentralised tanks located adjacent to main downpipes.

   Rainwater should be used for outdoors uses such as garden irrigation, and no potable water should be used for irrigation.

3. Consider recycling

   Grey water recycling is the process of treating waste water and reusing it, either within individual homes or buildings, or collectively across multiple buildings.

   At its most basic it involves collecting rainwater and the water used in taps, sinks, showers and baths, and processing it to enable it to be reused in toilets, washing machines and external taps.

   It is expected to be an increasingly important approach to driving potable water usage down to sustainable levels.

   Consider the range of greywater systems available, dependent on the scale of the project, the density of the housing types, the anticipated maintenance burden and the targeted water use reduction level.

4. Monitor and manage water

   Install water management systems to monitor and control consumption.

   Consider locating a water use display panel in close proximity to the kitchen tap to enable a clearer understanding of water usage in the home.

   Use the water use calculator iteratively throughout the project to check compliance with water-use reduction targets.