Simplifying SuDS with Flow Controls
Sustainable Drainage Systems – or SuDS – should soon become a requirement for developments throughout England. They are also increasingly being retrofitted to reverse the sealing-up of urban areas, moving towards the ‘sponge city’ paradigm and addressing flooding and pollution issues. But SuDS demand nature-based solutions using components at or near the surface to deliver multiple benefits.
The key to successful SuDS is water storage and treatment strategically deployed around a site within SuDS elements – such as swales, basins, ponds and, particularly, permeable paving – forming discrete sub-catchments, each defined by flow controls. With their low cost and shallow construction, Controflow orifice-based flow control chambers can be used more widely to manage flows at source, within each sub-catchment, and as part of the management train - as well as at site perimeters - whilst keeping water flow on or near the surface.
Avoiding Land-take
This approach avoids the loss of valuable development and amenity land and high costs of large, heavily engineered control or storage structures at the perimeter of developments.
It is unlike conventional drainage designs that have supposedly been adapted for SuDS but cannot meet the latest requirements. Those rely on gullies and pipes that transfer polluted runoff straight to expensive, underground tanks or ponds that fail to deliver amenity or biodiversity.
Flow control chambers designed specifically for SuDS are also essential to demonstrate agreed flow rates for regulators and to optimise spatial efficiency of SuDS features. They can also enable SuDS (notably permeable paving) on sloping sites, offer protection to downstream drainage assets and detain water to optimise ground infiltration, so reducing discharge volumes.
Flow controls enable water to be stored in each sub-catchment, gradually releasing it to flow to the next sub-catchment in the management train.
Surface Conveyance Systems
All orifice flow controls should be protected to prevent debris from entering the chamber, either with pre-filtering SuDS components, such as permeable paving, or Controflow inlet/outlet and surface conveyance systems for SuDS. The Controflow SuDS baskets are manufactured in stainless steel mesh and supplied with all the components for quick assembly on site, ready for filling with stone. Importantly for biodiversity, Controflow chambers and SuDS baskets – together with short pipe connections – reduce the risk of wildlife mortality dramatically.
Based on established engineering principles, Controflow products are specifically designed for all types of shallow SuDS elements with low flow rates, including permeable pavements, swales and basins – whether new-build or retrofit. They include straightforward, low-cost small orifice flow control chambers plus inlet/outlet and conveyance systems in place of unsightly headwalls and pipes - all replicating natural processes.
