Sustainable Drainage Report

Changes in Sustainable Drainage(SuDs) Requirements.

The EA has now handed over this responsibility to the local authorities. This has become a great matter of conern to planning applicants because each council seems to interpret the criteria in a different way , some using information ten years out of date.This leads to them asking for greater attenuation areas on a development which reduces development capacity.

Under the National Planning Policy Framework all developments are required to use methodology to slow down offsite flows to a highlyregimented degree. On some sites this is not possible but NPPF advises that developers should aim to improve off-site flows as far as possible.

Also certain areas are underlain by large potable water supplies which form a considerable source of water supplis throughout the country. It is then necessary to protect these waters from possible pollution by fitting special interceptors to clean the off-site water before it reaches the underlyingwater.

It should be noted that some local authorities are now asking for detailed drainage plans before they consider a planning application. This is the responsibility of the applicant rather than a flood assessor who is involved to check the possibility of flooding from all possible sources and to show that development and SuDs is achieveable.without the assessor being involved in detailed drainage design.