Londoners have been inadvertently waterproofing the capital over the last 40 years. Seventeen percent of permeable ground surface through which rainwater would normally flow, has been lost and covered up due to the trend of modern city-dwellers choosing to pave over their front gardens.
Sewers Fit To Burst
This is causing serious problems as the rainwater is now forced to flow down the streets of London and into the sewers beneath the city. These sewers are 150 years old and are close to capacity, so it is unfortunately estimated that by the year 2050, the streets are likely to be severely flooded. If no action is taken to correct this problem, then even an average fall of rain will probably cause flooding. As our climate in the UK will always anticipate the probability of bad weather, a plan must be put in place to deal with this concerning issue.
Fraser Ruthven, Head of Marketing and Growth for London Drainage Facilities, said: “London’s sewers have now reached a critical point where something must be done. Sustainable drainage is vital as it assists future generations in managing the flow rate of water from the streets as well as protecting the runoff from pollution”.
The Mayor of London, Boris Johnson in partnership with Thames London, the Environment Agency and the London Councils has recently revealed a draft scheme entitled ‘The London Sustainable Drainage Action Plan’ which is open for a consultation process for 3 months. The strategy outlines certain measures with which to divert rainwater back into the soil rather than putting excess pressure on the sewers. These measures include:
Raingardens with downpipes diverted into them, enabling the green space to soak up inches of excess rain from the surrounding area
Green Roofs on top of a building which are partially or completely covered in vegetation
Rainwater Harvesting – water is collected from roofs and drained down into rainwater tanks or water butts to be returned to the soil
Some scope for permeable resurfacing – possibly looking at changing the materials used in carparks, tarmacked areas or other hard surfaces and replacing them with appropriate permeable surfaces.
If agreed upon, the above measures would aim to reduce the surface water flows in the sewer network by 1% each year with the goal of a 25% reduction being met by 2040.
Furthermore, the draft action plan identifies certain ‘flooding hotspots’ in London which are thought to be more problematic than others. As you might expect, many of these hotspots are contained in Central London with those north of the Thames faring slightly worse than those south of the river.
Improving The Landscape
As well as being an important environmentally-friendly option, sustainable drainage will also completely overhaul the appearance of our capital. Current Londoners or those who are looking to move to London in the near future could benefit from the introduction of green roofs and raingardens which will cover up some of the greyer areas of the city and replace them with a more attractive streetscape full of green spaces, wildlife and ponds which will vastly improve our great city for the better.
Fraser Ruthven is the Marketing Associate for London Drainage Facilities, one of London’s leading drainage companies. London Drainage provides a wide range of drainage diagnostic and repair services in and around London.