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Underground Drainage > Surface Water Drainage >Storm Crates

Storm Crates

Drainage Central offer Brett Martin's Rain Bloc Attenuation Soak Away Crates.

Bloc Diamentions: L1200mm x W600mm x D420mm
One crate = 0.3m3
95% Void Ratio

All crates are manufactured from recycled material.

The Rain Bloc Storm Crate is ideal for soakaways, creating a temporary space for water to sit and eventually soak away.

This Storm Crate has a shallow installation depth with only 250mm cover required for driveway loading, meaning less digging and site spoil. It is also a high strength crate with a load bearing of up to 60 tonne when miniumum of 500mm cover is used.

How do I work out how many soakaway crates I need? (these notes are for general guidance only, it is dependant on the application - there are many different factors to take into account and usually a drainage engineer would do the calculations for an attenuation or infiltration system)

The full list of information preferred is as follows:

  • The geographical location of the site
  • The storm return period to be used
  • Catchment area(s)
  • Soil infiltration rate (derived from porosity tests) for soakaways
  • Ground water table level
  • Allowable outflow rate (for attenuation systems)
  • Safety factor to be applied
  • Drainage invert levelsIn a scenario for a single dwelling development where the ground is suitable for a soakaway, multiply the roof area by 0.02 to give a volume equal to 20mm of water over the roof (as per BS EN 752 ? 2008). That will give the cubic metres required. Remember, one crate is equal to 0.3m3 (cubed).

Basic Example

Roof Area 283.03m² x 0.02 = 5.67m³

18 crates would give 5.7m³ of capacity
This is only for single dwelling developments, and only for soakaways where the soil is suitable for soakaways; ie not clay. You cannot say for attenuation as everything depends on the allowable flowrate into the public sewer.
Rain Bloc Brochure.


rain bloc soakaway crate
Rain Bloc Soakaway Crate
Rain Bloc Attenuation Soak Away Crate 1200mm x 600mm x 420mm (0.3m3)
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Ex Vat: £57.48
(Inc VAT £68.97)