Ask the Expert: Drainage – The Importance of Consideration From the Outset of Development Plans8 August 2021
Liz Austin, principal drainage engineer at Enzygo, discusses the importance of considering drainage issues from the outset of development plans.
Enzygo Ltd are an independent, multi-disciplinary environmental consultancy with a proven track record of delivering creative, integrated and cost-effective solutions that maximise the potential of development sites. We use a collaborative approach to devise solutions that are respectful of technical and budgetary constraints, comply with industry guidance, whilst also fulfilling planning and commercial aspirations.
We have substantial experience in the delivery of all types of developments, including major infrastructure projects, residential housing schemes and renewable energy programs, across a broad range of environmental disciplines, including Planning, Air Quality, Hydrology and Drainage, Permitting and Regulation, Landscape, Ecology, Transport, Geo-Environmental and Hydrogeology, Noise and Vibration, and Arboriculture.
Our drainage team consider the impacts of flood risk and drainage on development schemes at the onset. Not considering drainage and SUDS within developments at the outset can cause issues when having to retrofit ponds, swales or other attenuation features into a constrained layout.
There has been a marked change in flood risk over the years of my career, a number of substantial changes have occurred. With Flood Risk and Drainage now becoming a material planning consideration, the sequential test, a move to above ground drainage features, volume control, a move away from variable runoff rates, and changing the way rainfall is calculated alongside the addition of climate change. There is now a move for development sites to mitigate flood impacts and provide betterment where practicable.
What we are now seeing is a greater demand from Local Authorities for detail within our drainage schemes, above ground features and promotion of multi train SUDS for water quality benefits.
Developers are now expected to do much more in terms of mitigating the impacts of runoff and water quality from development sites, ensuring that ecosystems would not be damaged. Driving these changes are tighter planning policies and supplementary planning documents. This is backed up by an evolving drainage technology market from quadraceptors for water quality to more low flow hydrobrakes.
As a result, it is more important than ever for those leading development projects to consider drainage implications from the outset to ensure that they are meeting required standards and to consider what mitigation may be likely and consider its feasibility in the design.
I would advise developers to involve an experienced drainage professional at the earliest opportunity to discuss any proposals. Enzygo can offer initial advice on local requirements, likely mitigation requirements and potential impacts and their implications from the development. We have unrivalled experience all across the UK and Ireland which enables our team to pull on many solutions to problems.
Taking these steps will hopefully reduce any nasty surprises as the projects near completion!
Enzygo then use their experience to support the development and the report to get the best solution for the project with the relevant authority.