If you’re planning to create a new driveway, whether an all-new facility or a replacement for what you have at present, the latest planning regulations demand you have to take account of environmentally friendly drainage considerations. In short, a permeable surface that allows water to pass through it is mostly required in your new driveway.
Your obligations
If you’re planning a new driveway, then if you are using a permeable surfacing material you won’t require planning permission whereas you will if you’re looking to lay an impermeable material onto an area of more than five square metres.
Permeable materials include gravel and porous asphalt while impermeable materials include concrete and tarmac. Some block paving is impermeable in itself, but if the gaps are filled with sand allowing water to pass through then this would be acceptable.
Gravel is an obvious choice for a true permeable surface, but it’s important to ensure the whole job is done with the right type of drainage in mind. It doesn’t want to be angled to encourage water to run off quickly – instead a cellular base will keep the gravel in place and make for a secure surface for consistent drainage.
A specialist Essex company offers what is a good example of these with their Suregreen porous pavers – a durable grid-like structure that is secured in place before filling the cavities and covering over the whole with gravel.
Current drainage concerns
More of the UK being covered over in hard surfaces with towns and cities expanding is creating a drainage problem – not helped by the changes in weather patterns, especially rainfall.
With hard surfaces like concrete or asphalt, as rain falls the water runs straight off it and eventually into the drains and ultimately to sewage treatment plants. The problem here is that many of the UK’s drains are unable to cope with the increased quantities of rainwater from increased amounts of hard surfaces.
Hard surface issues – the more hard surfaces, the more water that runs straight off them and into the drains instead of being absorbed naturally into the soil.
Climate issues – also, altering weather patterns are seeing more areas getting most of their rain in concentrated, shorter spells so the drains have less chance to channel water away relative to the speed and quantity it enters the sewer system. The result can be overflowing drains and flooding.
Sewerage issues – with basically clean water entering the drains from rainfall, it eventually travels to treatment plants to be filtered. There’s often no need for this as the water is, apart from maybe some light debris from roofs and ground surfaces, clean enough not to require large scale filtering so placing un-necessary demands on the treatment plants.
What is required?
A solution whereby the rain water runs naturally into the ground one way or another instead of being channelled directly into the drainage system. This can be achieved in part by using porous materials on new or replacement hard surfaces such as paving and driveways; the rain water passes through the porous material into the soil below to be absorbed naturally.
SUDS (Sustainable Urban Drainage System)
These take the drainage situation further; for example, instead of just letting water be absorbed into the ground in an arbitrary fashion it is controlled. In these cases, maybe a special soak away or underwater channel may be created to collect the water and move it elsewhere – perhaps to be stored for use when water is in short supply, or to a newly created recreational areas such as a pond or other body of water.
Other examples of a SUDS are swales; shallow soil and grass channels often by the side of roads designed to catch water running off from the adjacent hard surface and absorb it into the ground.
In essence, an SUDS helps rainwater naturally behave as it would have before building and hard surface creation occurred. In the case of water naturally draining through porous materials, it gradually takes its time to absorb and travel down towards the water table or an underwater channel to be collected and drained away in a manageable fashion.
Conversely, swift removal through drains sees large quantities of water travelling quickly to underground pipes and channels with the threat of overloading them.
Various options
In adhering to an obligation to assist rainwater drainage that alleviates the demands on sewers and treatment works, do think carefully about your materials and drainage arrangements.