Winnersh Triangle

The site, which was notoriously prone to flooding, was identified by both Reading and Wokingham Borough Councils as an ideal location for a new 390-space car park and ride, providing commuters with greater public transport options.

The site’s geology consists of a high-water table to cover level, meaning that an attenuation solution needed to be carefully considered.

Polypipe CGU provided a solution, consisting of 29 shallow Permavoid attenuation tanks, with the capacity to store up to 590m³ of stormwater runoff from the car park. Permavoid proved to be the ideal solution as it could be installed above the high water table.

Working with the design team, tanks were strategically positioned around the site to eliminate the need for the installation team (from Keytec Environmental Ltd) to be working within the ground water zone.

The Permavoid high-strength geocellular solution incorporates a unique jointing mechanism that forms an interlocking ‘raft’ with exceptional strength that will support structural loads across the most heavily trafficked areas on the site.

The surface finish consisted of both gravel and asphalt, with Polypipe CGU assisting the design team with structural and floatation calculations to ensure the minimum depth of sub-surface could be achieved, while preventing the geocellular tanks from floating.

In addition, Polypipe CGU worked with the main contractor, Dawnus, to ensure that the structural loading calculations were carried out to define the on-site travel routes for the different surface laying machinery. This allows surface works to be carried out without any detrimental effect to the Permavoid tank installations.

Richard Tithecott, Project Manager at Dawnus Construction, said: “The team from Polypipe CGU were a huge help on this project, not only in selecting the right product, but assisting with the necessary structural loading calculations.

“These calculations substantiated our belief that the specified Permavoid system was more than strong enough to cope with the loads likely to be placed on it, which was one of our primary considerations when selecting a shallow attenuation solution.”