DRAINAGE & PLUMBING


BRETT MARTIN TAKES FLOOD DEFENCES UNDERGROUND


T


he November 2019 floods in the East and West Midlands and areas of Yorkshire were yet another wake-up call that flooding is becoming more frequent and is the biggest impact on the UK of the climate crisis according to the Committee on Climate Change. With local authorities under increasing pressure to meet housing targets by having to build on flood plains, the natural barriers that once used to contain the water if a river burst its banks are frequently drained, reclaimed and used for housing.


Surface water drainage solution Through the adoption of 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.


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 approach 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 the new StormCrate55 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. Measuring 1200mm x 600mm x 347mm


PLASTIC FANTASTIC E


ven though water authorities are becoming more accepting of the use of plastic in drainage systems, there is still some scepticism surrounding its durability and performance from those who install below ground systems. With that being said, it’s true that some of the most robust and flexible drainage solutions are now made from plastic.


Strong but flexible


During their lifespan, below ground pipes can sometimes be subject to heavy impact, which can affect their performance. Earthquakes, landslides, overflowing rivers or something as common as heavyweight vehicles all pose a threat to underground drainage. Tim Wootton, technical services manager at Wavin, says: “Therefore, it’s vital that the material used is strong yet flexible enough to withstand these environmental pressures. When it comes to plastic, this means having an accreditation by agencies such as The European Plastic Pipes Fitting Association (TEPPFA).” In a recent experiment, the TEPPFA aimed to


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Time is of the essence Ensuring projects are on time is essential for any development, as delays with drainage can impact the delivery of the entire piece


and weighing only 15.5kg per module StormCrate55 units can be lifted by hand and laid or stacked in rows. There are 4 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 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, StormCrate55s have a high void ratio of 95% which means that the units are highly efficient at storing up to 237.5L litres of water in the event of heavy rains. BMJ


While technological developments offer new and exciting ways of enhancing drainage systems, it can sometimes be hard to break tradition and place trust in new materials.


test the strength of plastic by collating reports from over 100 independent sources from across the globe that documented how plastic pipes responded to extreme environmental impacts compared to other materials. The study concluded that “only plastic pipes and their joints can resist common strains by providing a functional safety barrier”, proving their resilience. Wootton adds: “Although the strength of plastic largely contributed to these results, it’s also important to note the role that flexibility plays. The malleability of plastic allows the pipe to compress and deform when faced with added strain, causing the pressure to be disbursed, therefore reducing the risk of cracking. Our Osma UltraRib range is a key example of this; its ribbed profile provides enhanced axial and radial strength, but installation is easy and safe, due to its flexible and lightweight nature and the fact that no heavy plant equipment is required.”


of infrastructure. Wootton says that this is particularly important with below ground installations, as they are often the initial phase of any development. “Specifying products with a quick and easy installation is therefore a necessity, and plastic systems provide just that. For example, in 2013 TEPPFA measured the installation time of 90 metres of plastic piping and two plastic inspection chambers, with it taking just three hours and 19 minutes. Due to their lightweight nature, they also require no heavy machinery, helping to improve safety on site.”


Use, reuse and use again Sustainability is growing ever more crucial in building design, and another long-term benefit of plastic is that it can be recycled and repurposed while not sacrificing its effectiveness. It can therefore play an important part of the circular economy. “At Wavin, we have a dedicated recycling policy whereby we purchase third-party used plastics to be used across our range of products. We take old materials such as double-glazing window frames and other waste products from the housing industry and use them in our manufacturing process. This technology has been applied to our multi-layer, solid-core pipes, which contain over 50 per cent recycled content, but still deliver the same performance as the virgin plastic pipes they replace.”BMJ


www.buildersmerchantsjournal.net February 2020


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