PLUMBING & DRAINAGE T
he UK is facing another winter of devastating weather with Storms Bella and Christophe causing severe flooding across many parts of the UK, leaving disruption and damage in their wake. But with the Government aiming to build 300,000 new homes a year by the mid-2020s to ease the housing shortage, contractors need to be armed with flood prevention solutions, particularly if they are faced with the challenge of building sites located on flood plains. It’s why engineered Sustainable Drainage Systems (SuDs) are one of the simplest ways to tackle surface water and address the challenges faced by extreme weather events.
According to the Committee on Climate Change, flooding will have the biggest impact on the UK in our changing climate. Much more needs to be done to address the risk of surface water flooding. The natural barriers that once contained water if a river burst its banks are frequently drained, reclaimed and used for housing. Drainage systems may not have the capacity to deal with extra flood water. It means that new developments must be made resilient to flooding with mitigation measures that manage water where it falls, reducing the demand on built drainage and the sewerage infrastructure.
A runaway drainage solution Ian St-John, specification manager – South East from Brett Martin says that, whilst permeable ground including fields, grass and woodland can absorb water through infiltration, new build developments reduce the number of permeable surfaces. Excess surface water then overwhelms drains and rivers leading to flash floods. “Through the adoption of a SuDS approach to managing water, contractors can manage the risk of surface flooding, integrating these solutions into developments, whilst influencing other aspects of the site and reducing impermeable areas wherever possible,” he says. 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, he adds, 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.
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FLOOD PREVENTION GOES UNDERGROUND
We’re only two months into 2021 yet the pictures of flooding across the country are already increasing. BMJ looks into why merchants need to be part of the solution by being on board with SUDS.
Engineered approach
“Faced with rising costs and stricter deadlines, modularisation is growing in popularity as contractors look to builder’s merchants to find the next generation of efficient and economical products and systems,” St-John says. “Due to the numerous benefits both on and off site, underground modular geocellular units such as our StormCrate55 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 15.5kg per module and measuring 1200mm x 600mm x 347mm, the StormCrate55 modular units can be easily lifted by hand and then laid or stacked in rows. Designed and developed by Brett Martin, there are four units per 1m³ which simplifies calculations, and the crate is high strength with a loading capability of 562kN per m³. The units are suitable for installation in landscaped areas, pedestrianised spaces, playgrounds, parking areas, driveways and access zones.
The crates 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 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, StormCrate55s have a high void ratio of 95% which means that the units are highly efficient at storing up to 237.5 litres of water in the event of heavy rains.
“Our changing and volatile climate has meant intensive showers and flood risk issues are here to stay. The need to manage surface water is critical, which is why engineered solutions such as our StormCrate55 can work in association with traditional SuDS solutions to provide effective flood protection and make homes and businesses resilient to future flooding,” he continues. BMJ
www.buildersmerchantsjournal.net February 2021
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