Park and Ride to SUDS

Thickthorn

The Thickthorn Park and Ride, Norwich, at the interchange of the A11 and A47 Trunk routes was the culmination of several years’ infrastructure improvements by Norfolk County Council to the City’s points of entry by road.

Stormbloc® infiltration modules from Hydro International were chosen to ensure that stormwater runoff from the car park complied with Sustainable Drainage Systems (SUDS) principles, as well as withstanding loading from the varying depths of backfill and traffic levels.

The total area of the development of over 500,000 m2 comprises a new access to the main roads as well as the car parking facility of around 30,000 m2; enough for more than 700 cars, it includes bus stops and landscaping.

Antony Jackson, of consulting engineers Mott MacDonald explained: “The car park is on a slope and paved with standard asphalt, which drains to gullies and surface channel drains.  The SUDS area beneath the car park extends to 4,000 m2 of soakaway, using around 2,000 m3 of the Stormbloc®.  As the soakaway layer has to be flat to ensure even infiltration, this meant that the Stormbloc® modules had to withstand a loading of some 3.5 m of soil at the deepest point, in addition to vehicles”.

“Following the Environment Agency’s requirement to manage the surface water drainage from the site without discharge to a nearby watercourse, we considered various soakage systems,” commented Antony Jackson, “however the depth of fill meant that expensive, imported lightweight material would have been required.  Stormbloc® was able to take the loading of the existing site fill and remove the need for special provisions for site plant trafficking: also, the on-site mixture of sand and gravel and a cohesive soil provides better infiltration than we had anticipated.  Additionally, Stormbloc®’s design means it can be easily inspected and jetted to keep it free of silt, if required.”

Read the full Thickthorn case study

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