London may have to resort to building a ‘Bazalgette 2’ system – which would make the Thames Tideway Tunnel ‘look like a Lego kit’ – if it does not attend to pressing water management concerns.
So said Alex Nixon, policy and programmes manager for the GLA at a special breakfast talk on ‘Water drainage, strategies of a modern city’, held at the NLA this morning.
Nixon said the drastic measure of building a new system to cope with London’s sewerage system – which is currently ‘at capacity’ – may only be allayed by extensive greening and other measures, with the Thames Tunnel ‘a necessary evil’ to cope with an enlarged city. ‘Bazalgette built a combined sewerage system for London’, he said. ‘The chances are that, unless we start to take a very long-term perspective on this, we will be forced by regular flooding to building another one that will make the Thames Tideway Tunnel look like a Lego kit.’
Londoners need to be better informed about the need to conserve water, making better connections between water and the environment and even making a better use of waste water as a potential source of clean energy. ‘People do not equate water efficiency with their energy bill’, said Nixon. We also need to look at retrofitting our homes and our businesses, he added, and cannot keep adding to our existing 150-year-old drainage system and expect it to keep performing. The number of homes in London with a water meter – just one in five – also needs to be lifted if behaviour is to be changed. As it is, Londoners use some 167 litres of water per person per day, amounting to 10% above the UK average.
The GLA has compiled a map which shows London’s susceptibility to surface water flooding at some 300 hotspots, a scenario which is worsened by the fact that an area the size of two-and-a-half Hyde Parks are lost by people ‘concreting over’ their gardens, every year. In terms of rainfall, we have also had two 1-in-100-year events in the last decade, plus a couple of one-in-400 year events. ‘It is fairly shocking. We are very, very vulnerable to surface water flooding’, said Nixon.
To address these problems, part of the approach is significantly more urban greening, but also to raise the profile of such issues through three ‘deep green makeovers’ currently being carried out, with work in schools on water management issues aimed at harnessing ‘pester power’ to spread to parents in their homes and workplaces.
AECOM director of sustainability Celeste Morgan said that there are lessons to be learned by the UK from the rest of the world, particularly from Europe and Australia, where Water Sensitive Urban Design (‘a verb, not a noun, and a process, not a product or a feature’) has been successful in making systems which not only work well, but look good too. One scheme in Melbourne, for example, uses a ‘zero water’ approach where no external water supply is used beyond that rainwater which is captured on site, resulting in a 99 per cent security of supply. But in the UK we are ‘still obsessed with flooding, attenuation and end up with big structures’. Schemes tend to be ‘terribly ugly’, whereas projects should be ‘far more about place, and about a great city that looks great’, with more designers and placemakers involved in water management.
A good example of design in this area, however, is being provided at the Olympic Park, said Phil Askew, project sponsor at the Olympic Park Legacy Company. The ponds, waterway treatments and planting it has carried out along the River Lea and across the park site will provide biodiversity and a ‘complicated but incredible site for London’s future.’
By David Taylor, Editor, New London Quarterly