Project overview

A three-house residential development in Bungay, Norfolk, needed a sustainable drainage solution to manage surface water and reduce flood risk. The development itself sits within Flood Zone 1, with surrounding village carrying a notable flood risk, which made it especially important to control rainwater close to where it falls.

The challenge

The local soil's high clay content meant water would drain away too slowly for an infiltration-based system to work effectively. The site instead needed a way to capture significant volumes of rainfall and release it gradually, easing pressure on the surrounding drainage network rather than adding to it during heavy storms.

The solution

HAURATON's DRAINFIX BLOC HD was specified to build two underground attenuation tanks. One, measuring 5.5m by 8m by 0.8m, was installed beneath a driveway, with a second tank measuring 3m by 11m by 0.8m built into softer ground destined for landscaping.

Each tank was formed from a double layer of crates set inside an impermeable geomembrane, sealed with tape, then wrapped in a protective fleece and covered to distribute surface loading evenly. Specialist contractors from DS Moore carried out the installation.

Why retention rather than infiltration

Retention and infiltration represent the two principal SuDS storage strategies, and the right choice depends on ground conditions. Retention systems hold rainwater temporarily before releasing it slowly into the drainage network or nearby watercourses, smoothing peak flows, easing pressure on sewers, and reducing the risk of flooding, erosion, and water quality issues downstream. Given the area's clay-heavy soil and tendency toward a high water table, a retention approach paired with an impermeable membrane suited this site better than an infiltration-based alternative.

Inside DRAINFIX BLOC HD

DRAINFIX BLOC HD has a dual-crate design with closed outer crates that establish the structure's boundary without separate end panels, while open inner crates nest efficiently for transport.

Each crate holds around 383 litres of water at 95.8% void space, and the system is manufactured from fully recycled, PVC-free polypropylene that remains recyclable at end of life. Because the same range supports both retention and infiltration projects it needs to be paired paired respectively with an impermeable membrane or a permeable geotextile. It can be expanded in any direction after installation, providing flexibility for sites where storage needs may change over time.

Outcome

“DRAINFIX BLOC HD represents an important addition to the HAURATON range in supporting SuDS projects. This product can support both infiltration and retention projects, and it was great to see the expert installation by Andy and Russell from DS Moore on site” “DRAINFIX BLOC HD can be used in areas with a high water table, so is an ideal choice for developments in the low-lying area of Norfolk”.

  • Simon Wilkinson, HAURATON Area Manager for North London and East Anglia,

The project reflects a wider shift in UK planning policy: the National Planning Policy Framework was strengthened in 2024–2025 to push SuDS provision further up the agenda for new developments.

For the local developer behind the scheme, the system meant being able to deliver on a personal commitment to managing rainwater responsibly for the benefit of the wider community.