Do pervious pavements really need pervious surfaces? The concept of the macro-pervious pavement as a SuDS device

Pervious pavements, as part of sustainable drainage systems, have a long history but there is some resistance to their use based on worries over pavement life and difficulties associated with clogging. Whilst stormwater run-off rates and volume controls that arise from a pervious pavement certainly do not require a pervious surface (i.e., the storage and infiltration of water could be equally well achieved no matter how the water is directed underground), it is the water quality issues dependent on the filtration through the pervious surface which are receiving more attention. The purpose of this study is to illustrate that this is not the case and that a pavement with a sub-surface storage and treatment zone can operate effectively when water is directed underground by suitably designed, discrete, infiltration points. These infiltration points serve to trap the majority of pollutants in the upstream part of the treatment train where they can be dealt with via a simple maintenance schedule. In particular this study reports up to date results from an on-going study on a macro-pervious pavement in Scotland and on studies on systems which utilise oil separators installed either to take stormwater from individual gulley pots, or within channel drains, serving a pervious sub-base.