From the ground up

In the face of rapid urbanisation, Andrew Cullum of Polypipe makes a case for Sustainable Drainage Solutions (SuDS), exploring how effective water management solutions can enhance flood resilience while providing environmental benefits for years to come

The recent launch of the Government’s Industrial Strategy brought together ideas from a number of different department white papers and construction sector reviews to lay the foundations of how the UK will tackle the need for more homes in urban centres, and the reality of having to make use of land prone to flooding.

According to the Government’s recent housing figures, 217,350 new homes have been added to the UK housing market in the past financial year – the highest build rate since 2007. Coinciding with the rise in new housing, the number of extreme weather events in the UK has quadrupled in recent years, posing potential flood risk to densely populated urban centres, where drainage and storm management systems are already under considerable strain.

Cities such as York and Carlisle have all suffered following seasonal deluges in recent years.

Sustainable Drainage Solutions (SuDS) are the first line of defence against floods in heavily urbanised areas, where a lack of natural ‘soak away’ features can prevent rainfall from draining away naturally. Combined with the increased level of seasonal rainfall, this places immense pressure on the existing drainage infrastructure, and can lead to management systems being overwhelmed. However, with intelligent design, SuDS can collect, store and control the flow of excess surface water, to prevent water logging, and help to avoid sewer systems becoming overwhelmed, guarding against flooding during periods of high rainfall.

The latest Government Industrial Strategy outlines further funding set aside to help mitigate flood risk, with £2.6 bn being committed to provide new flood alleviation schemes across the UK. By increasing investment in flood defence now, predicted flood damage costs could be reduced to below today’s level by the year 2080.

Furthermore, to ensure natural assets within development areas are being taken into consideration from initial planning stages, the Government will be committing to a 25-year Environmental Plan, while the £1.7 bn Transforming Cities Fund will look at new and better ways to incorporate natural resources to aid water management.

These measures indicate that SuDS planning and flood resilience will be of increasing importance at the planning stages of all new housing developments, whether in the city centres, or the suburbs. The level of committed funding should give developers and architects greater scope to look at new means of water management.

Typically, stormwater is stored and attenuated at ground level, however on already developed sites, creating new systems at this level can drive up project costs, and is not always feasible. To overcome the lack of ground space, architects and developers can opt for above ground podium and rooftop SuDS solutions, such as blue and green roofs.

Providing numerous environmental benefits, rooftop and podium level SuDS capture, store and release stormwater at a controlled rate. Combining building drainage and irrigation, green roofs and blue roofs are planted over a waterproof membrane that stores and attenuates surface water. The water captured can

either be stored and released back to the drainage system at a rate agreed by the local water company, or re-used for functions such as potable water for toilet flushing.

Green rooftop solutions also encourage biodiversity by enabling the plantation of seeds and local vegetation which are sustained through rainwater. This in turn can provide recreational areas for resident use. Within city centres where pollution is most concentrated, the increased levels of vegetation can also help to remove pollutants from the air, improving air quality and offering health benefits for locals.

With the Government looking to kickstart a building revolution by committing £2.5 billion funding to build affordable homes, architects and developers have access to the tools to build homes that can not only house, but enhance the lives of tenants and homeowners.

For developers, investing in whole sale, intelligently engineered SuDS solutions ensures our urban areas are resilient to future weather events, reducing damage caused by floods. As urbanisation continues at such an unprecedented rate, it is important that land developers consider SuDS right from the very first drawing to enhance flood resilience in urban centres and ensure robust and reliable drainage solutions able to meet long-term demands.

Andrew Callum is the general manager of water management solutions at Polypipe