The housing development had previously flooded during heavy rainfall due to interaction between surface water sewers and the water level in the nearby Ouseburn River. To prevent future flooding, Polypipe CGU’s Permavoid system was installed under a recreational area between a road and the river.
The water management solution comprised of a Permavoid shallow geocellular system, also featuring the use of Permavoid Biomat, which was incorporated into the design to trap and retain any residual and emulsified oils that may be present in surface water from the road before discharging directly into the river.
As surface water enters the Permavoid attenuation system through kerb drainage, the Permavoid cells had to be installed below the level of the road at the same time at being above the normal river level. As the system is designed for shallow applications, the burial depths could be tightly controlled to ensure the optimum attenuation performance was achieved.
River water is prevented from entering the system by a non-return valve on the outlet.
