Niall Greenan, Head of Civil Engineering at Lyons O’Neill
The UK is in a state of emergency. The coronavirus outbreak has demanded urgent action to halt its spread and prevent our health services becoming overwhelmed. Responding to the virus has required strong government leadership and the cooperation of individuals and businesses to curb rising case numbers. Research and expert knowledge has also proved essential in discovering more about the disease and exploring new ways of managing its impact.
But the UK – and the world – was already in a state of emergency before this current crisis began. Climate breakdown may be occurring more gradually but it’s equally as urgent and needs a similarly coordinated response. This February’s mass flooding was another stark reminder that, if left unchecked, climate change will wreak increasing havoc on landscapes and livelihoods.
Responding to the climate change emergency is the responsibility of every individual, company and national government, but must be of particular concern for the construction industry. Buildings and construction accounts for almost 40% of energy-related carbon dioxide (CO₂) emissions and has a great impact on the natural environment. It’s up to all of us working in this sector to do all we can to meet the climate change challenge.
One key way this can be achieved is through the use of sustainable water management techniques. These techniques seek to avoid environmental destruction caused by surface runoff and reduce unnecessary pollution by allowing for water reuse. The importance of such methods in addressing climate change was highlighted in October’s Government response to the Committee on Climate Change 2019 progress report, which cited Sustainable Drainage Systems (SuDs) as a crucial part of national government strategy.
The role of SuDS is to ensure that water moving in and around a site mimics the natural movement of water and any surface water is drained efficiently and sustainably. It differs from traditional drainage methods by refusing to direct water to nearby drains and offers opportunities for water storage. SuDS also allows for pollutant removal which reduces the risk of pollutants leaching into the surrounding environment and means the processed water can be reused for other purposes. By controlling surface water runoff and allowing for water recycling, SuDS therefore minimises environmental damage, decreases flood risks and helps reduce water wastage.
SuDS are increasingly becoming a legal requirement in UK construction. The National Planning Policy Framework (NPPF), last revised in February 2019, states that major developments should incorporate sustainable drainage systems unless there is clear evidence that this is inappropriate. The systems installed must also take account of advice from the lead local flood authority (LLFA), have appropriate proposed minimum operational standards, include maintenance arrangements to ensure an acceptable standard of operation for the lifetime of the development and, where possible, provide multifunctional benefits.
f you want your project to benefit from SuDS then this should be factored into plans from the very beginning of the design process. A civil and structural engineer will conduct a thorough site investigation – and even employ techniques such as 3D modelling – to explore the below ground drainage challenges of the site in question. They will also conduct capacity checks and investigate foul and surface water pumping stations and then use all this information to create a bespoke drainage strategy.
SuDS have a key role to play in minimising environmental damage at a local and national level but they can also help individual projects meet their sustainability goals. They have a significant impact on a project’s BREEAM rating, for example. This was seen in our work at Harris Academy Purley, a three storey school near the Fiveways intersection in Croydon, which achieved an “Excellent” BREEAM rating. In order to achieve this goal, our team designed an infiltration system to discharge the surface water from the site to the water table, so the local water cycle would not be disrupted. The credits won through these techniques proved invaluable in gaining the high level score.
SuDs aren’t just invaluable in the education sector. Our work at the Childs Terrace housing development in Northolt also involved SuDS techniques to achieve a sustainable design. Water butts were installed within the gardens so residents could reuse rainwater for gardening and reduce their water use. An attenuation tank was also designed to accommodate 1 in 100 year storm events for all the remaining surface water on site.
In the face of global challenges like climate change, the choice of certain drainage systems may seem insignificant. However, every decision has a cumulative effect. If we want to protect future generations from increased flooding, water shortage and environmental destruction then sustainable water management needs to be a priority. We can’t afford to ignore the climate change emergency.