Geocellular storage systems are modular plastic crate units installed underground to provide attenuation storage for surface water runoff. They are widely used in SuDS designs where above-ground storage is not feasible due to site constraints, land take limitations, or where the development layout does not allow for open features such as detention basins or ponds.

The key advantages of geocellular systems include:

High void ratio: Typically 90-95% void space, meaning almost all of the excavated volume is available for water storage. This contrasts with aggregate-filled systems, which provide only around 30% void space.
Structural capacity: Modern geocellular units are engineered to withstand traffic loading (up to SLW 60 tonnes in some products), allowing them to be installed beneath car parks, access roads, and other trafficked areas.
Compact footprint: The high void ratio means smaller excavations compared to alternative storage methods, reducing construction costs and land take.
Modular construction: Units clip together to form tanks of any plan shape and depth, adapting to irregular site geometries.

Geocellular systems can serve three functions:

Attenuation only: Stored water is released at a controlled rate via a flow-control device (hydrobrake or orifice plate) to a downstream watercourse or sewer
Infiltration: Where ground conditions permit, the system is wrapped in geotextile and water soaks into the surrounding soil, functioning as a large soakaway
Combined: Partial infiltration with overflow to a controlled outlet

Geocellular tanks require upstream treatment (such as silt traps and bypass separators) to prevent clogging of the void space with sediment. Maintenance access points must be provided for inspection and jetting.

Aegaea specifies geocellular storage where appropriate within our drainage design service, balancing cost, buildability, and long-term maintenance requirements.

Geocellular Storage