Sustainable Urban Drainage Systems
Posted on 25/Jan/2008
Whatever you think of Sustainable Urban Drainage Systems it’s unlikely you’ll be able to avoid them in the near future.
Dramatic changes in weather and increased developments on Greenfield sites have put enormous strain on existing drainage systems, sometimes causing serious flooding. The Government’s latest Planning Policy Statement makes it very clear that Local Authorities should be considering SUDS to prevent flooding and the subsequent damage and pollution. Every new building development is now likely to be scrutinised to make sure it’s contributing to the Government’s targets to increase the sustainability of urban environments.
How will SUDS affect me?
Your Local Authority will want to know how you intend to tackle the increased rainwater run-off resulting from new buildings and hard landscaping. Essentially they’ll want any run-off to be as close to the original amount from the site before development. Fortunately for the builder there are a number of ways of tackling this – one tried and tested method is the FlowBlock system.
What is FlowBlock?
Flowblock is a polypropylene modular water storage cell that’s easy to install and environmentally-friendly. By locking them together you can quickly create underground storage tanks and soakaways – both of which can support a planning application where SUDS are specified. The modules can be used individually for small domestic situations or connected together to create large, high-capacity storage systems.
Why use it?
One of the key planning objectives in the Government’s policy statement is: “reducing flood risk to and from new development through location, layout and design, incorporating SUDS” The FlowBlock system reduces that risk by retaining surface water underground and then gradually releasing it. This helps to avoid the surges that can overwhelm existing drainage systems and cause flooding. FlowBlock has already proven its performance in SUDS across the UK with thousands of cubic metres in widespread use. What’s more FlowBlocks are also BBA certified so you know that it is a quality product.
How does FlowBlock work?
By creating an underground storage chamber with FlowBlocks, rainwater run-off can be restricted in one of two ways. The first is attenuation – in other words the controlled release of stored water in to the main drainage system / watercourse. This is achieved by wrapping the FlowBlock construction in an impermeable geomembrane and fitting a flow control device at the outlet point. The release rate can then be set to suit the capacity of the existing drainage system. The second is by using FlowBlocks to create a soakaway. In this situation the construction is wrapped in a permeable geotextile which allows the stored water to gradually seep back into the ground and replenish the natural water table – often another key consideration in planning applications.
Where can I site them?
Soakaways have to be placed at least 5 metres away from any foundations but attenuation tanks can be sited almost anywhere. And because they’re modular this makes them ideal for awkward shaped areas. FlowBlocks come in two different load strengths; FlowBlock Lite is for pedestrian areas while the standard FlowBlock can be used in heavy-duty situations such as service yards, car parks and other trafficked areas.
Can I install FlowBlock myself?
The modules are lightweight and easily assembled on site by stacking together using the shear connectors provided. Stormwater management can supply all the relevant materials to you within 24 hours from stock and the blocks themselves come with a 50-year guarantee. However Stormwater also offer a full installation service that will provide you with a 30-year warranty for the installed system.
All News