SuDS (Retention) for a Norfolk Residential Development

Project Requirements & Solution

The development of three houses required the installation of two attenuation tanks, the first (5.5m x 8m x 0.8m) positioned under a drive and the other (3m x 11m x 0.8m) in soft ground to be landscaped with vegetation.

Each tank consisted of a double layer of crates laid into an impermeable geomembrane. The membrane was sealed around the tank with tape and the tank was then wrapped in a protective fleece, before being covered to ensure effective distribution of the anticipated surface load.

Why Retention?

Retention systems temporarily store excess rainwater and release it slowly into drainage networks and natural waterways. This controlled discharge reduces peak flows, prevents sewer overload, and mitigates flooding. By holding back runoff during heavy rainfall, retention systems help prevent erosion, protect water quality, and stabilise downstream water levels. They play a crucial role in managing stormwater sustainably, especially in areas where infiltration is limited due to soil or site conditions.

With the soil in the local area of the project having high clay content and therefore low permeability, conditions were best suited to the use of a retention system vs infiltration.

The current situation for SuDS within new developments in the UK (2026)

Schedule 3 of the Flood and Water Management Act 2010 requires all new developments to include SuDS provision, although this particular piece of legislation is currently not in force in England. However, the government has strengthened the National Planning Policy Framework (NPPF) to heavily promote SuDS in new developments as of 2024-2025; the pressure on government to implement legislative measures to ensure planned developments don’t fall through the cracks continues.

Value Realised with HAURATON

In the case of this residential project, DRAINFIX BLOC HD has enabled the developer (a local businessman) to reinforce his commitment to his local community by ensuring that rainwater is managed responsibly and sustainably on-site.