A more sustainable way of managing surface water runoff to prevent sewer flooding and to improve water quality in rivers is to create Sustainable Urban Drainage Systems (SuDs). This also helps reduce our energy use as surface water is not unnecessarily treated as wastewater. They also create greener and more diverse surroundings in urban areas.
‘Urban creep’, loss of green space, climate change and population growth all put pressure on the sewerage network. Urban creep also puts pressure on the environment, as pollutants from transport and industry are washed off of impermeable surfaces and into rivers. There is no single solution to address this and different circumstances require different approaches.
Ponds are among the landscape features which can reduce or delay rainwater run-off into sewers.
We recognise that we need to manage the quantity and quality of surface water entering our sewers, as well as building more capacity where it is needed. We have therefore been working to develop alternative approaches to surface water, using green infrastructure such as rain gardens, permeable paving and water butts, to either return rainwater to the ground, or to slow it down and clean it before it enters our sewers.
Working in partnership with London Borough of Southwark, during 2013/14 we started plans on a scheme to alleviate the risk of flooding in Herne Hill, Dulwich by attenuating surface runoff using SuDS.
Our pilot trial in West London called ‘Greenstreets’ is testing the feasibility of retrofitting SuDS to existing streets. As well as testing their effectiveness, the trials will identify the challenges involved in delivering SuDS and the attitudes of the public and other stakeholders towards them.
We expect SuDs will prove beneficial for controlling the quantity and quality of surface water runoff, as well as improving biodiversity and local amenity. SuDS also help clean up surface water runoff by removing pollutants such as silt and oil. Along with reducing discharges from storm overflows, this improves river quality.
Combating sewer flooding