SuDS are Good News for London – says Boris

Written By: European Sales Director, Hydro International

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Surface water drainage and flood risk management have been flagged as key challenges for the UK’s capital city in the Mayor’s London Infrastructure Plan 2050. The drainage network is already over capacity and rainfall of just 2mm already causes combined sewer overflows into the River Thames.

Population growth and climate change are only going to exacerbate flood risk and water quality problems brought about by a history of inadequate infrastructure investment, says the report now inviting comments in a city-wide consultation.

The Mayor’s plan sets out its stall for Green Infrastructure and Sustainable Drainage Systems (SuDS) are recognised for their critical role in delivering value in urban environments as part of an integrated water management approach.

Following the example of other great international cities like Philadelphia the report calls for “a paradigm shift” in the way existing resources and new facilities are planned, designed, integrated and managed. New institutional and governance arrangements are required, it says, and in response is setting up a multi-agency Green Infrastructure Task Force.

The report tells us the Mayor will lead on developing a Sustainable Drainage Action plan for London that will set out the proposals and actions to manage the risk of surface water and sewer flooding. This will be published in late 2014 for consultation, with a final plan in place in by the middle of 2015.

All of this is good news for the City and the health and well-being of its people and environment. London will also provide a vital lead for progress elsewhere in the UK and around the world.

The resilience of infrastructure to flood risk is a critical issue for consideration, says the plan. London has done badly in qualifying for flood defence funding, which has placed a lower value on economic development and infrastructure as a justification compared to protecting residential properties.

In the battle for better flood resilience and an integrated approach to urban water planning, SuDS have a vital role to play. London is a cramped and crowded city, so the Mayor will need to select from the full SuDS toolbox to balance flood risk and green features effectively. When funds are in short supply, London boroughs will also need reliable and maintainable drainage systems that can deliver predictable flood control and water quality performance.

There are already some great best practice examples both from Thames Water and the London boroughs – reflecting both the oldest and the newest solutions.

Hydro already has significant experience of using its Hydro-Brake® Flow Controls in urban retrofit applications and an early scheme for London – Wadley Road in Waltham Forest – goes back to the 1980s. Nine controls were retrofitted strategically in manholes in this flood-hit area to hold back flood water by utilising 260 m3 of surface water storage capacity within the sewer system and adjacent above-ground areas.

The system, which featured on the popular TV programme Tomorrow’s World at the time, is still working effectively. As part of the sustainable drainage plan, the Mayor sets out his stall to work with partners and establish incentives to encourage landowners to capture more rainwater on new and existing development, open and green spaces.

If Tomorrow’s World was around today, we might see Maggie Philbin scaling a ladder to get a better look at a blue roof. A blue roof uses the same Hydro-Brake® technology to provide an excellent means of retrofitting water retention in a built-up urban environment – providing temporary storage and controlled discharge of rainwater.

It can be integrated with a wider managed SuDS system or provide water for irrigation, toilets or vehicle washing. In fact, Hydro’s first blue roof installation took place some 10 years ago atop an out-of-town shopping complex and is still fully functioning.

Not even Boris Johnson can escape the shadow of the European Water Framework Directive and implementing SuDS for effective water quality will be essential in the city’s 25 year planning. In the tight urban spaces, above-ground features can surely play a part in dealing with litter, sediments and pollutants. However, to get the best water quality treatment, manufactured devices such as Downstream Defender® hydrodynamic vortex separators or the Hydro Filterra™ bioretention system can provide invaluable and fully-maintainable solutions. For more details learn about Hydro StormTrain® Series of surface water treatment devices and try out the Treatment Selection Tool.

Read other blogs by Phil Collins

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