Brian Wilson of Tobermore explores how the changing climate is urgently increasing the need for sustainable urban drainage systems (SuDS).
Climate change is the talk of the moment, with consumers being encouraged to reduce and monitor their water consumption.
Flooding in summer and winter is now a feature of our changing climate. 2018 saw unprecedented levels of rainfall, which brought devastating flooding to areas of the UK, destroying homes, belongings and livelihoods.
Last year’s floods, and those in preceding years, have many causes, and it would be wrong to lay the blame on one single reason. However, there is no doubt that the laying of impermeable ground surfaces such as concrete and tarmac has reduced permeability, and rainwater has had nowhere to infiltrate to. The British drainage and sewer system is at its maximum capacity in many areas, particularly in the regions where the highest level of flooding has been experienced.
Worryingly, recent research shows that extreme flooding may become more frequent in the UK due to climate change, with almost five times more heavy rainfall events predicted to exceed 28 mm in one hour in the future than currently. With the continuing unpredictability of our weather all year round, permeable paving is now a necessity.
In the UK there is a growing acceptance that a more sustainable approach is needed to manage rainfall and flooding. If flood water is effectively managed, it can be recycled and used when needed. Through a sustainable urban drainage system (SuDS), storm water can be absorbed by permeable paving through enlarged joints, which are filled with grit instead of the sand used in conventional paving, and stored in a special sub base beneath the paving. This acts like a huge tank, and the aggregate that is used for the sub base filters out most of the pollution that may have been washed off the roads and roofs.
Justification
Of course, the question of cost always raises its head when considering SuDS solutions. There is a general consensus that permeable paving is an expensive solution.
However, when the overall drainage costs are taken into consideration, permeable paving can be a very cost-effective solution compared to traditional methods. Many permeable paving ranges can be machine laid, reducing both labour costs and project completion times.
It is also worth bearing in mind that, unlike some other SuDS solutions, permeable paving does not require any additional land take, and so does not reduce the number of viable units on a housing project.
In terms of design, permeable paving can enhance the style, character and visual appearance of a home. Permeable paving is increasingly manufactured with the same aesthetic benefits of the non-permeable product equivalent, ensuring that style is not compromised when employing a functional SuDS solution.
Looking to the future of permeable paving, 2019 will see more innovation in permeable paving product styles, with manufacturers creating interesting permeable paving styles and designing additional laying patterns, moving away from the more traditional herringbone-laid rectangular paving.
Legislation
Today, few would disagree with the principle that SuDS and techniques such as permeable paving are needed to help fight flooding and pollution – particularly with overloaded sewers, urbanisation and climate change.
In April 2015, the Government introduced new planning guidelines for the use of SuDS on any new housing site with more than 10 units. The aim of the guidelines is to ensure that any new development has measures in place for combating potential flooding issues. Wales presents a good example of this.
As of 7 January this year, proposed new developments must be served by sustainable drainage systems which comply with the Welsh Ministers’ Standards, and which are approved by the SuDS Approving Body (SAB).
This is a very important milestone in a long journey towards full acceptance of the importance of SuDS in the UK, which is obviously good news for suppliers, who will hope to see increased demand for water management products and services.
Furthermore, the Environment Agency recommends that where appropriate, storm water source control measures, which also improve water quality, should be incorporated into a development proposal. They are essential for any new development in areas where existing sewerage systems are at full capacity.
With the recent flash floods in parts of England, it appears highly likely that this legislation will be adopted throughout the rest of the UK.
Brian Wilson is sales manager at Tobermore