Beat the floods with SuDS

By David Sturrock, Brett Martin Plumbing & Drainage regional sales manager (Scotland)

IN recent years, severe flooding has devastated the country, affecting the economy and people’s lives.  With these unpredictable changes in climate, we need to consider how we build new homes to address and prevent these risks.

Solutions such as Sustainable Drainage Systems (SuDS) help developers and housebuilders to manage excess stormwater on their developments, combating the disastrous effects which flooding can cause.

The pressing need for more homes has caused us to build on flood plains, urbanising our green spaces. As these developments proceed there is a knock-on effect, as we have less land for rainfall to be able to permeate the ground. It is imperative that water is managed where it falls, reducing the demand on built drainage and the sewerage infrastructure.

A comprehensive flood prevention solution

By taking a SuDS approach to managing water, housebuilders and developers can manage the risk of surface flooding, integrating these solutions into developments, whilst at the same time influencing other aspects of the site and reducing impermeable areas wherever possible.

Planning guidance requires all major new housing developments of ten houses or more to incorporate SuDS for the management of surface water run-off, yet bear in mind this doesn’t apply to smaller developments or the retrofitting of SuDS in urban environments.

Sustainable drainage mimics natural drainage processes by allowing rainfall to soak into the ground where possible or by delaying discharges. Reducing both the volume and rate of surface water run-off to sewers and watercourses, this helps to improve water quality, ecology and amenity value of watercourses. It is important, however, to remember that there is no single drainage solution for any one site.

There are a number of options from natural above ground SuDS solutions including swales, detention ponds, basins and permeable surfaces, to engineered solutions such as concrete culverts, plastic pipes, attenuation tanks and soakaways.

Modularisation is the way forward

Faced with rising costs and stricter deadlines, modularisation is growing in popularity as contractors look to find the next generation of efficient and economical products and systems. Due to the numerous benefits both on and off site, underground modular geocellular units such as StormCrate from Brett Martin Plumbing and Drainage have become an increasingly popular choice at every stage of the supply chain, from the architect and specifier to the contractor and client.

Weighing in at only 18kg per module and measuring 1200mm x 600mm x 420mm, the StormCrate modular units can be easily lifted by hand and then laid or stacked in rows. The units are suitable for a range of applications including residential, commercial and industrial projects.

StormCrates can either be wrapped in a geotextile, which allows stored water to slowly seep into the surrounding ground and back into the water table, or a more common practice, wrapped in an impermeable geomembrane to create a sealed underground tank. The outlet from this tank is then controlled to facilitate a slow release of the stored water back into the drainage system over a longer period.

Manufactured from recycled plastic, StormCrates have a high void ratio of 95%, which means that the units are highly efficient at storing up to 300 litres of water in the event of heavy rains. If inspectability is required for future maintenance, then Brett Martin can offer StormCrate Inspect Crates.

There are no limits on the use and design of the surface over the system and StormCrates may be successfully installed under parking areas, driveways and landscaped areas.

Managing a storm

For a new housing development in Coventry, surface water management was a key consideration to prevent any future flooding, hence Brett Martin’s StormCrates were used to create an underground attenuation tank for the temporary storage of stormwater, reducing the demand on built drainage.

The development of 15 new homes – a mixture of two, three and four-bed semi-detached terraced and detached houses – was built on an area which is susceptible to flooding. In order to manage rainwater within the site and prevent flooding during periods of bad weather, contractor O’Flanagan Homes required a drainage solution that could be integrated within the site and found the solution in StormCrate.   

Brett Martin provided O’Flanagan Homes with 180 StormCrates which were used to create a 54.5m3 underground storage tank, constructed in three layers at a depth of two metres beneath the entrance road, to offset stormwater run-off from the developed area. 

Commenting on the installation, Danny O‘Flanagan of O’Flanagan Homes commented, “We have used StormCrates on other projects and they are an ideal solution for managing stormwater run-off. Lightweight, easy to move and incredibly strong, we used them to create an underground tank beneath the permeable paving in the entrance road of the development.”

The use of StormCrates from Brett Martin Plumbing and Drainage ensured this new housing development had a proven rainwater attenuation solution which will reduce demand on built drainage and the sewerage infrastructure.