Polystorm Modular Water Storage Units, a recent addition to Polypipe’s range of below-ground drainage products, have the great advantage of adaptability. The units, each one metre long x 0.5 metre wide x 0.4 metres deep and weighing only 9 kilograms, can be interlinked in any shape or size required to provide an effective load-bearing tank structure to receive collected rainwater from gutters and/or surface drains. The flexibility granted by modular construction means that Polystorm is equally suited as part of an urban sustainable solution for domestic and large scale sites and can be used in narrow strips and awkwardly shaped areas as well as simpler rectangular or square drainage areas.

Polystorm’s adaptability does not end there for it can be used either as a conventional Soakaway System for gradual drainage release into the natural water table or as an Attenuation System. In Attenuation mode the assembled underground tank structure is wrapped in an impermeable geomembrane so that in storm conditions excess rainwater is stored for release into sewer pipes within set discharge limits, thus preventing surface flooding. Taking residential developments as an example the tank capacity would be designed to absorb rainwater from a ‘one-in-a hundred years’ storm without any flooding in the property.

With a minimum 40 tonnes per sq.m. compression strength, Polystorm will withstand any normal loading while a storage capacity of around 190 litres per unit [a 95% voiding ratio] provides an impressive drainage capability. The units require comparatively shallow excavation and a full accessory range of brick bond connectors, clips, shear connectors, adaptors and reducers aids the simplicity and speed of installation.

As well as the standard Basic Silt Trap an Advanced Silt Trap is also an option, incorporating a silt bucket for larger objects and a secondary filtration unit for smaller particles, both in stainless steel. The standard trap flow is maximum 15 litres per second but other capacities can be manufactured to order. Silt trap accessories include circular and square covers & frames, risers and sealing rings.
The inherent advantages of the modular system plus efficiency and minimal maintenance in both Soakaway and Attenuation modes makes Polystorm the sustainable solution for most rainwater drainage situations.