British Geological Survey launch Infiltration SuDS Map

The ‘National Standards for Sustainable Drainage’ have been released by DEFRA for consultation and are expected to be implemented in October 2012. They specify guidelines for the design, construction, operation and maintenance of sustainable drainage systems (SuDS), a term which encompasses a number of surface water management techniques, which are distinguished in the National Standards by the surface water runoff destination. Two such techniques are discharge to the ground (soakaways, infiltration basins, permeable pavements) and discharge to watercourses (detention basins and ponds). The National Standards require that a hierarchical approach to SuDS selection is adopted, with discharge to the ground being prioritised over discharge to surface water bodies, sewers and combined sewers respectively. The prioritisation of infiltration is consistent with current building regulations (Approved Document H) and is often a cost effective means to reduce off-site surface water flow rates to required greenfield rates. The feasibility of implementing infiltration SuDS is however highly dependent on the design of the system and on the compatibility of that design with the geological and hydrogeological properties of the subsurface.