SITE PREPARATION


Paving responsibly for rainwater runoff


Chris odson from Interpave explains the importance of taking a responsible approach to rainwater runoff from paving around both new and existing homes to protect them and the wider community


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nother year of flooding around the  provides a timely reminder of the importance of sustainable drainage SuS and permeable paving in the fight against flooding. As our towns and cities continue to grow, more rainwater is captured on streets, car parks, drives, roofs and other sealed surfaces – which then flows into sewers, rivers and streams. xisting drainage systems simply cannot cope, causing downstream flooding. In addition, roads, car parks and driveways collect pollution – from car exhausts, tyre and brake wear including electric vehicles, oil leaks and other sources – and when it rains this gets washed into sewers, harming rivers and streams.


WE MUST ACT NOW


Climate change means more frequent and heavy rainstorms leading to more flooding. This is because sealing up’ our towns and cities also stops rainfall soaking into the ground naturally. The water table levels drop causing more water shortages, streams and ponds to dry up, and trees to be deprived of water. It could also affect the foundations of your home, particularly on clay soils, as they dry out and shrink. These problems are made worse when


gardens are sealed-up too, particularly when water runs straight to roads and sewers. Of course, one small area of paving in isolation is not going to cause major flooding – but the cumulative impact of numerous properties can. or example, the area of paving in front gardens for car parking in ondon is equivalent to around 5,200 football pitches. Simply allowing rainwater to run straight off roofs and paving into drains is no longer an option.


SUSTAINABLE DRAINAGE SOLUTIONS or over 20 years, it has been recognised that SuS are essential in curbing


jan/feb 2023


flooding and pollution from rainwater runoff. SuS manage rainwater by slowing it down and cleaning it up – copying, as closely as possible, the natural drainage from a site before any building work takes place. SuS manage rainwater near the surface and as close to its source as possible, slowing the flow and providing additional benefits including clean water for wildlife, planting or recycling. Typical SuS include living or green roofs and permeable paving, as well as planted features like rain gardens. or new developments, SuS will generally be required as part of the planning process, although this will depend on which part of the country. In some cases, a single house may be exempt but, increasingly, local policies affecting planning applications will demand SuS. or example, the ondon lan’ says that development proposals for impermeable paving should be refused where appropriate, including on small surfaces such as front gardens and driveways.


sing SuS is a low-cost solution, and the responsible thing to do.


PAVING AROUND EXISTING HOMES or some time now there has been wide-ranging encouragement to use SuS widely. Although changes to planning rules in both ngland and Scotland were instigated years ago, growing awareness of the importance of permeable paving in the fight against flooding means increasing enforcement by local authorities in the light of climate change.


Installing drives or other paving anywhere in your garden used to be considered permitted development’ – in other words an automatic planning permission. ut these rights have been removed from new or replacement paving – unless it’s permeable paving’ or drains onto a permeable area within the


property, planning permission will need to be sought. If you are creating a new drive or parking space, you must also have dropped kerbs’ onto the public highway with a special highway authority licence and, in some cases, planning permission. Again, the drive should meet permeable’ requirements and not drain water onto the road. oing against these requirements could result in local authority enforcement action or legal problems when the house is sold.


PERMITTED PAVING Interpave’s aving for ain’ – referred to in government rules and free to download – offers guidance on concrete block permeable paving, which allows


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