Future challenges | Polypipe on surface water management

Managing surface water in urban areas has the potential to enhance the environment. benefits already seen are just the beginning.

Imagine a future where instead of looking out over a sea of grey roofs, all you can see are meadows – but you are still in a city centre. Maybe it sounds like a pipe dream, but for some there is a firm belief that this could become reality by the time NCE hits its 100th anniversary.

Central to this greening of the urban landscape is the widespread adoption of blue-green infrastructure – combining planting with water attenuation to reduce surface water run off rates. This solution can be used on roofs and building podiums – whether new or as a retrofit option – and as rain gardens and tree pits at ground level.

Growth of blue-green infrastructure

Among those who anticipate a greater uptake of this approach are Polypipe Civils and Green Urbanisation’s business development director for specification Nicholas Wright and Polypipe green urbanisation innovation manager Charlotte Markey. Speak to either for a few minutes and you will realise that this belief is based on firm facts and that they are both working to provide the additional evidence they say is key to delivering on their predictions.

“Blue-green infrastructure is currently a niche market,” says Wright. “But in 50 years’ time, its use should be the norm.”

The attraction of the solution is clear for developers, local authorities and communities living around – and even looking down on – blue-green infrastructure. Essentially, it creates green spaces in what might otherwise be hard landscaping, adding biodiversity and slowing down – or even stopping - the rate at which stormwater reaches the sewer network. Wright describes the blue-green solution as creating a shallow attenuation system that provides green field run off rates of rainwater from a building as if it was not there.

While there is a long way to go before the majority of roofs and all ground level landscaping use this design, the industry has already come a very long way in the last 10 years.

According to Wright, change started to happen and blue-green solutions started to become accepted in around 2014. “We went from talking to landscape architects about rainwater harvesting to talking to the developers and consultants,” he says. “Our conversations were quite insular at the start but we soon realised that the key to wider acceptance of blue-green infrastructure was wider conversations.”

Blue-green infrastructure is currently a niche market. But in 50 years’ time, its use should be the norm

There was a real need to educate the design teams about the solution and that “it wasn’t creating a swimming pool on the roof” or creating a maintenance issue.

Polypipe’s first project to refurbish an existing roof with blue-green infrastructure came in 2016 when Polypipe was asked to find a solution for an existing green roof in London that had died. A green roof is one with just planting, no water attenuation. Seacoal House’s roof was an eyesore to those looking down on it but the blue-green approach improved its look, reduced run off and created new recreation areas for staff working in the building.

On a project that followed, the water attenuation capacity provided by the roof meant that surface water storage tanks in the basement could be removed to add valuable, lettable parking spaces.

“The added value that blue-green solutions can deliver has been a real driver for change,” says Markey.

Wright adds that the market has already developed rapidly and he predicts that Polypipe will not be doing what it does today in 10 years’ time.

Acceptance drives innovation

“We are already seeing repeat customers and schemes becoming more elaborate and adventurous,” he says.

This growing acceptance is driving that innovation. Markey adds: “The increase in interest has meant there is more competition in the market than 10 years ago in terms of product ranges but this in turn has delivered more benefits with a higher level of innovation as manufacturers have sought to remain competitive.

“We also now have builders merchants asking for off the shelf products, so blue-green solutions could soon move away from just being bespoke products.”

Wright and Markey expect the next big step change in adoption and wider use to be data driven rather than product driven. Data is essential to quantify the value blue-green solutions bring.

Markey is currently working on a project in Liverpool to install some modestly sized rain gardens, but the client has asked Polypipe to also install sensors to monitor the operation of the design. This data will be used to improve future designs and optimise sites selected for blue-green solutions to maximise the benefits.

“Data and interrogation of that data over the next 10 years will enable us to do more,” says Markey.

She adds that it is this data that is critical to taking blue-green infrastructure to the next level of adoption. “One of the challenges is the volume that you need on a large site at masterplan scale and the perceived price and capital investment necessary at the outset can seem high,” she says.

The added value that blue-green solutions can deliver has been a real driver for change

“This is where the data is important as it demonstrates the long term strategy to manage the water and create a low maintenance solution that delivers a return on investment. Projects we are working on at the moment will deliver a better data set to show the benefits of investing now for long term gain.”

In addition to creating a clear business case and more advanced solutions, Wright believes that there is a need for education about blue-green infrastructure. But he does not mean just creating better understanding with clients, developers and building owners – he is talking about working with schools to widen knowledge about the industry.

Wright is currently working on a scheme to build a “learning garden” with a range of Polypipe products such as passive irrigation and smart controls for a school in Thamesmead.

“We need to invite younger minds into our industry and demonstrate all the career paths available to them,” he says. “More collaboration will come from working with a wider palette of individuals.”

If Wright and Markey manage to instil just a small part of their passion for blue-green infrastructure into the next generation of specifiers and adopters, the sector has a very bright future in terms of skills and the solutions to manage surface water flooding and combat climate change.